On Sun, 11 Feb 2024 07:28:39 -0800, John Larkin <jl@997PotHill.com>
wrote:

>On Sun, 11 Feb 2024 10:39:49 +0100, Jeroen Belleman
><jeroen@nospam.please> wrote:
>
>>On 2/11/24 02:22, John Larkin wrote:
>>> On Sat, 10 Feb 2024 22:33:15 +0100, Jeroen Belleman
>>> <jeroen@nospam.please> wrote:
>>>
>>>> On 2/10/24 18:27, Don wrote:
>>>>> Jeroen Belleman wrote:
>>>>>> Don wrote:
>>>>>>> Jan Panteltje wrote:
>>>>>>>> John Larkin wrote:
>>>>>>>>> Cursitor Doom wrote:
>>>>>>>>>> John Larkin wrote:
>>>>>>>>>>> Fred Bloggs wrote:
>>>>>>>>>>>
>>>>>>>>>>>> This is the new circuit analysis: exploring operation in Spice and looking at graphs.
>>>>>>>>>>>>
>>>>>>>>>>>> https://www.elektormagazine.com/articles/circuit-analysis-with-ltspice-12v-lamp-flasher
>>>>>>>>>>>
>>>>>>>>>>> Too much talking for too little circuit.
>>>>>>>>>>
>>>>>>>>>> Mr. Bloggs had to use LTspice for a 12V lamp flasher?? Jeez!
>>>>>>>>>
>>>>>>>>> Using Spice is reasonable, easier than computing exponentials by hand.
>>>>>>>>> I use Spice for voltage dividers, filters, rectifiers, RLC delays, all
>>>>>>>>> sorts of stuff.
>>>>>>>>
>>>>>>>> I mostly use pepper, Chili and salt as spices, some sugar etc.
>>>>>>>> If this spice stuff continues people will need it before throwing a ball...
>>>>>>>> Why not just ask AI to design the circuit for you,?
>>>>>>>>
>>>>>>>> And no guarantee that anything in LTspice works -in- or even resembles reality!
>>>>>>>>
>>>>>>>> Real hands on testing is needed to get a clue.
>>>>>>>
>>>>>>> Tis true the Spice won't help you
>>>>>>> With a simple radio set:
>>>>>>>
>>>>>>> <https://crcomp.net/crystalrx/a.png>
>>>>>>> [...]
>>>>>>
>>>>>> Why not?
>>>>>
>>>>> Good question. And, with all due respect, you ought to post some Spice to
>>>>> show me how you do it.
>>>>>
>>>>> Danke,
>>>>>
>>>>
>>>> Something akin to this.
>>>>
>>>> Jeroen Belleman
>>>>
>>>> ================================================
>>>> Version 4
>>>> SHEET 1 880 680
>>>> WIRE -144 96 -176 96
>>>> WIRE -32 96 -64 96
>>>> WIRE 272 96 176 96
>>>> WIRE 352 96 272 96
>>>> WIRE 464 96 416 96
>>>> WIRE 512 96 464 96
>>>> WIRE 544 96 512 96
>>>> WIRE -176 128 -176 96
>>>> WIRE -32 128 -32 96
>>>> WIRE 176 128 176 96
>>>> WIRE 272 128 272 96
>>>> WIRE 464 128 464 96
>>>> WIRE 544 144 544 96
>>>> WIRE -176 240 -176 208
>>>> WIRE -32 240 -32 208
>>>> WIRE 176 240 176 208
>>>> WIRE 272 240 272 192
>>>> WIRE 464 240 464 208
>>>> WIRE 544 240 544 208
>>>> FLAG 176 240 0
>>>> FLAG 272 240 0
>>>> FLAG 464 240 0
>>>> FLAG 544 240 0
>>>> FLAG -32 240 0
>>>> FLAG -176 240 0
>>>> FLAG 512 96 out
>>>> SYMBOL ind2 160 112 R0
>>>> SYMATTR InstName L1
>>>> SYMATTR Value 16µ
>>>> SYMATTR Type ind
>>>> SYMBOL cap 256 128 R0
>>>> SYMATTR InstName C1
>>>> SYMATTR Value 6.28n
>>>> SYMBOL diode 352 112 R270
>>>> WINDOW 0 32 32 VTop 2
>>>> WINDOW 3 0 32 VBottom 2
>>>> SYMATTR InstName D1
>>>> SYMATTR Value AA112
>>>> SYMBOL res 448 112 R0
>>>> SYMATTR InstName R1
>>>> SYMATTR Value 1meg
>>>> SYMBOL cap 528 144 R0
>>>> SYMATTR InstName C2
>>>> SYMATTR Value 10n
>>>> SYMBOL ind2 -48 112 R0
>>>> SYMATTR InstName L2
>>>> SYMATTR Value 16µ
>>>> SYMATTR Type ind
>>>> SYMBOL bv -176 112 R0
>>>> WINDOW 3 -186 181 Left 2
>>>> SYMATTR InstName B1
>>>> SYMATTR Value V=10k*(1+sin(time*1k*2*pi))*sin(time*1meg*2*pi)
>>>> SYMBOL res -48 80 R90
>>>> WINDOW 0 0 56 VBottom 2
>>>> WINDOW 3 32 56 VTop 2
>>>> SYMATTR InstName R2
>>>> SYMATTR Value 1
>>>> TEXT 72 0 Left 2 !.tran 5m
>>>> TEXT 0 112 Left 2 !K12 L1 L2 1u
>>>> TEXT -152 0 Left 2 ;Transmitter
>>>> TEXT 264 0 Left 2 ;Crystal set receiver
>>>
>>> Suggestions:
>>>
>>> Reduce the modulation a bit. It distorts at 100%.
>>>
>>> Make R1 2K, like an old dynamic headphone.
>>>
>>> Change the coupling to 50u. A good antenna makes a lot of signal.
>>>
>>> You can use a BAT54 schottky.
>>>
>>
>>
>>You don't expect high fidelity from a crystal set, but OK, fair enough.
>>C2 was meant to model a piezo earbud. I should actually measure one...
>>
>>I got the values of C! and L1 wrong. C1=300pF is more reasonable,
>>and then L1=84.43uH. In practice, of course, C1 would be tuned and L1
>>would be fixed at 80uH or so, but either way works.
>>
>>The voltage of B1 and the tranformer coupling factor are just guesses,
>>based on the knwoledge that crystal sets actually do work.
>>
>>Jeroen Belleman
>
>I think that most xtal sets do some sort of impedance matching from
>the antenna up into the main coil, taps on the coil or an extra
>winding. A really longwire antanna will have a lot of capacitance and
>an equivalent lowish impedance.
>
>The people who have made xtal sets over the last century or so don't
>seem to have been very quantitative.
>
>I've wondered if I can slurp enought power out of the air to light an
>LED. My office is in a wooden building about 3 miles from Sutro Tower.
>Castro valley is a bowl that I suspect focusses the RF onto us.

LEDs require relatively large amounts of current, so I don't see how
that would be possible, John. There's only *one* bloke I can think of
who could conceivably pull that off and he's long dead, sadly.
Edison's nemesis:

https://en.wikipedia.org/wiki/Nikola_Tesla

On Sun, 11 Feb 2024 17:40:10 +0000, Cursitor Doom <cd@notformail.com>
wrote:

>On Sun, 11 Feb 2024 07:28:39 -0800, John Larkin <jl@997PotHill.com>
>wrote:
>
>>On Sun, 11 Feb 2024 10:39:49 +0100, Jeroen Belleman
>><jeroen@nospam.please> wrote:
>>
>>>On 2/11/24 02:22, John Larkin wrote:
>>>> On Sat, 10 Feb 2024 22:33:15 +0100, Jeroen Belleman
>>>> <jeroen@nospam.please> wrote:
>>>>
>>>>> On 2/10/24 18:27, Don wrote:
>>>>>> Jeroen Belleman wrote:
>>>>>>> Don wrote:
>>>>>>>> Jan Panteltje wrote:
>>>>>>>>> John Larkin wrote:
>>>>>>>>>> Cursitor Doom wrote:
>>>>>>>>>>> John Larkin wrote:
>>>>>>>>>>>> Fred Bloggs wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>> This is the new circuit analysis: exploring operation in Spice and looking at graphs.
>>>>>>>>>>>>>
>>>>>>>>>>>>> https://www.elektormagazine.com/articles/circuit-analysis-with-ltspice-12v-lamp-flasher
>>>>>>>>>>>>
>>>>>>>>>>>> Too much talking for too little circuit.
>>>>>>>>>>>
>>>>>>>>>>> Mr. Bloggs had to use LTspice for a 12V lamp flasher?? Jeez!
>>>>>>>>>>
>>>>>>>>>> Using Spice is reasonable, easier than computing exponentials by hand.
>>>>>>>>>> I use Spice for voltage dividers, filters, rectifiers, RLC delays, all
>>>>>>>>>> sorts of stuff.
>>>>>>>>>
>>>>>>>>> I mostly use pepper, Chili and salt as spices, some sugar etc.
>>>>>>>>> If this spice stuff continues people will need it before throwing a ball...
>>>>>>>>> Why not just ask AI to design the circuit for you,?
>>>>>>>>>
>>>>>>>>> And no guarantee that anything in LTspice works -in- or even resembles reality!
>>>>>>>>>
>>>>>>>>> Real hands on testing is needed to get a clue.
>>>>>>>>
>>>>>>>> Tis true the Spice won't help you
>>>>>>>> With a simple radio set:
>>>>>>>>
>>>>>>>> <https://crcomp.net/crystalrx/a.png>
>>>>>>>> [...]
>>>>>>>
>>>>>>> Why not?
>>>>>>
>>>>>> Good question. And, with all due respect, you ought to post some Spice to
>>>>>> show me how you do it.
>>>>>>
>>>>>> Danke,
>>>>>>
>>>>>
>>>>> Something akin to this.
>>>>>
>>>>> Jeroen Belleman
>>>>>
>>>>> ================================================
>>>>> Version 4
>>>>> SHEET 1 880 680
>>>>> WIRE -144 96 -176 96
>>>>> WIRE -32 96 -64 96
>>>>> WIRE 272 96 176 96
>>>>> WIRE 352 96 272 96
>>>>> WIRE 464 96 416 96
>>>>> WIRE 512 96 464 96
>>>>> WIRE 544 96 512 96
>>>>> WIRE -176 128 -176 96
>>>>> WIRE -32 128 -32 96
>>>>> WIRE 176 128 176 96
>>>>> WIRE 272 128 272 96
>>>>> WIRE 464 128 464 96
>>>>> WIRE 544 144 544 96
>>>>> WIRE -176 240 -176 208
>>>>> WIRE -32 240 -32 208
>>>>> WIRE 176 240 176 208
>>>>> WIRE 272 240 272 192
>>>>> WIRE 464 240 464 208
>>>>> WIRE 544 240 544 208
>>>>> FLAG 176 240 0
>>>>> FLAG 272 240 0
>>>>> FLAG 464 240 0
>>>>> FLAG 544 240 0
>>>>> FLAG -32 240 0
>>>>> FLAG -176 240 0
>>>>> FLAG 512 96 out
>>>>> SYMBOL ind2 160 112 R0
>>>>> SYMATTR InstName L1
>>>>> SYMATTR Value 16µ
>>>>> SYMATTR Type ind
>>>>> SYMBOL cap 256 128 R0
>>>>> SYMATTR InstName C1
>>>>> SYMATTR Value 6.28n
>>>>> SYMBOL diode 352 112 R270
>>>>> WINDOW 0 32 32 VTop 2
>>>>> WINDOW 3 0 32 VBottom 2
>>>>> SYMATTR InstName D1
>>>>> SYMATTR Value AA112
>>>>> SYMBOL res 448 112 R0
>>>>> SYMATTR InstName R1
>>>>> SYMATTR Value 1meg
>>>>> SYMBOL cap 528 144 R0
>>>>> SYMATTR InstName C2
>>>>> SYMATTR Value 10n
>>>>> SYMBOL ind2 -48 112 R0
>>>>> SYMATTR InstName L2
>>>>> SYMATTR Value 16µ
>>>>> SYMATTR Type ind
>>>>> SYMBOL bv -176 112 R0
>>>>> WINDOW 3 -186 181 Left 2
>>>>> SYMATTR InstName B1
>>>>> SYMATTR Value V=10k*(1+sin(time*1k*2*pi))*sin(time*1meg*2*pi)
>>>>> SYMBOL res -48 80 R90
>>>>> WINDOW 0 0 56 VBottom 2
>>>>> WINDOW 3 32 56 VTop 2
>>>>> SYMATTR InstName R2
>>>>> SYMATTR Value 1
>>>>> TEXT 72 0 Left 2 !.tran 5m
>>>>> TEXT 0 112 Left 2 !K12 L1 L2 1u
>>>>> TEXT -152 0 Left 2 ;Transmitter
>>>>> TEXT 264 0 Left 2 ;Crystal set receiver
>>>>
>>>> Suggestions:
>>>>
>>>> Reduce the modulation a bit. It distorts at 100%.
>>>>
>>>> Make R1 2K, like an old dynamic headphone.
>>>>
>>>> Change the coupling to 50u. A good antenna makes a lot of signal.
>>>>
>>>> You can use a BAT54 schottky.
>>>>
>>>
>>>
>>>You don't expect high fidelity from a crystal set, but OK, fair enough.
>>>C2 was meant to model a piezo earbud. I should actually measure one...
>>>
>>>I got the values of C! and L1 wrong. C1=300pF is more reasonable,
>>>and then L1=84.43uH. In practice, of course, C1 would be tuned and L1
>>>would be fixed at 80uH or so, but either way works.
>>>
>>>The voltage of B1 and the tranformer coupling factor are just guesses,
>>>based on the knwoledge that crystal sets actually do work.
>>>
>>>Jeroen Belleman
>>
>>I think that most xtal sets do some sort of impedance matching from
>>the antenna up into the main coil, taps on the coil or an extra
>>winding. A really longwire antanna will have a lot of capacitance and
>>an equivalent lowish impedance.
>>
>>The people who have made xtal sets over the last century or so don't
>>seem to have been very quantitative.
>>
>>I've wondered if I can slurp enought power out of the air to light an
>>LED. My office is in a wooden building about 3 miles from Sutro Tower.
>>Castro valley is a bowl that I suspect focusses the RF onto us.
>
>LEDs require relatively large amounts of current, so I don't see how
>that would be possible, John. There's only *one* bloke I can think of
>who could conceivably pull that off and he's long dead, sadly.
>Edison's nemesis:
>
>https://en.wikipedia.org/wiki/Nikola_Tesla

A good LED is visible in typical room light at 1 uA, which would be
about 2 uW. I'd imagine that a modest antenna and a decent detector
could do much better than that.

The difference between a crystal set and lighting an LED is that the
LED case should use the entire spectrum, AM TV FM, which is densely
packed where I am. That would take some thinking.

On Sun, 11 Feb 2024 10:32:32 -0800, John Larkin <jl@997PotHill.com>
wrote:

>On Sun, 11 Feb 2024 17:40:10 +0000, Cursitor Doom <cd@notformail.com>
>wrote:
>
>>On Sun, 11 Feb 2024 07:28:39 -0800, John Larkin <jl@997PotHill.com>
>>wrote:
>>
>>>On Sun, 11 Feb 2024 10:39:49 +0100, Jeroen Belleman
>>><jeroen@nospam.please> wrote:
>>>
>>>>On 2/11/24 02:22, John Larkin wrote:
>>>>> On Sat, 10 Feb 2024 22:33:15 +0100, Jeroen Belleman
>>>>> <jeroen@nospam.please> wrote:
>>>>>
>>>>>> On 2/10/24 18:27, Don wrote:
>>>>>>> Jeroen Belleman wrote:
>>>>>>>> Don wrote:
>>>>>>>>> Jan Panteltje wrote:
>>>>>>>>>> John Larkin wrote:
>>>>>>>>>>> Cursitor Doom wrote:
>>>>>>>>>>>> John Larkin wrote:
>>>>>>>>>>>>> Fred Bloggs wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> This is the new circuit analysis: exploring operation in Spice and looking at graphs.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> https://www.elektormagazine.com/articles/circuit-analysis-with-ltspice-12v-lamp-flasher
>>>>>>>>>>>>>
>>>>>>>>>>>>> Too much talking for too little circuit.
>>>>>>>>>>>>
>>>>>>>>>>>> Mr. Bloggs had to use LTspice for a 12V lamp flasher?? Jeez!
>>>>>>>>>>>
>>>>>>>>>>> Using Spice is reasonable, easier than computing exponentials by hand.
>>>>>>>>>>> I use Spice for voltage dividers, filters, rectifiers, RLC delays, all
>>>>>>>>>>> sorts of stuff.
>>>>>>>>>>
>>>>>>>>>> I mostly use pepper, Chili and salt as spices, some sugar etc.
>>>>>>>>>> If this spice stuff continues people will need it before throwing a ball...
>>>>>>>>>> Why not just ask AI to design the circuit for you,?
>>>>>>>>>>
>>>>>>>>>> And no guarantee that anything in LTspice works -in- or even resembles reality!
>>>>>>>>>>
>>>>>>>>>> Real hands on testing is needed to get a clue.
>>>>>>>>>
>>>>>>>>> Tis true the Spice won't help you
>>>>>>>>> With a simple radio set:
>>>>>>>>>
>>>>>>>>> <https://crcomp.net/crystalrx/a.png>
>>>>>>>>> [...]
>>>>>>>>
>>>>>>>> Why not?
>>>>>>>
>>>>>>> Good question. And, with all due respect, you ought to post some Spice to
>>>>>>> show me how you do it.
>>>>>>>
>>>>>>> Danke,
>>>>>>>
>>>>>>
>>>>>> Something akin to this.
>>>>>>
>>>>>> Jeroen Belleman
>>>>>>
>>>>>> ================================================
>>>>>> Version 4
>>>>>> SHEET 1 880 680
>>>>>> WIRE -144 96 -176 96
>>>>>> WIRE -32 96 -64 96
>>>>>> WIRE 272 96 176 96
>>>>>> WIRE 352 96 272 96
>>>>>> WIRE 464 96 416 96
>>>>>> WIRE 512 96 464 96
>>>>>> WIRE 544 96 512 96
>>>>>> WIRE -176 128 -176 96
>>>>>> WIRE -32 128 -32 96
>>>>>> WIRE 176 128 176 96
>>>>>> WIRE 272 128 272 96
>>>>>> WIRE 464 128 464 96
>>>>>> WIRE 544 144 544 96
>>>>>> WIRE -176 240 -176 208
>>>>>> WIRE -32 240 -32 208
>>>>>> WIRE 176 240 176 208
>>>>>> WIRE 272 240 272 192
>>>>>> WIRE 464 240 464 208
>>>>>> WIRE 544 240 544 208
>>>>>> FLAG 176 240 0
>>>>>> FLAG 272 240 0
>>>>>> FLAG 464 240 0
>>>>>> FLAG 544 240 0
>>>>>> FLAG -32 240 0
>>>>>> FLAG -176 240 0
>>>>>> FLAG 512 96 out
>>>>>> SYMBOL ind2 160 112 R0
>>>>>> SYMATTR InstName L1
>>>>>> SYMATTR Value 16µ
>>>>>> SYMATTR Type ind
>>>>>> SYMBOL cap 256 128 R0
>>>>>> SYMATTR InstName C1
>>>>>> SYMATTR Value 6.28n
>>>>>> SYMBOL diode 352 112 R270
>>>>>> WINDOW 0 32 32 VTop 2
>>>>>> WINDOW 3 0 32 VBottom 2
>>>>>> SYMATTR InstName D1
>>>>>> SYMATTR Value AA112
>>>>>> SYMBOL res 448 112 R0
>>>>>> SYMATTR InstName R1
>>>>>> SYMATTR Value 1meg
>>>>>> SYMBOL cap 528 144 R0
>>>>>> SYMATTR InstName C2
>>>>>> SYMATTR Value 10n
>>>>>> SYMBOL ind2 -48 112 R0
>>>>>> SYMATTR InstName L2
>>>>>> SYMATTR Value 16µ
>>>>>> SYMATTR Type ind
>>>>>> SYMBOL bv -176 112 R0
>>>>>> WINDOW 3 -186 181 Left 2
>>>>>> SYMATTR InstName B1
>>>>>> SYMATTR Value V=10k*(1+sin(time*1k*2*pi))*sin(time*1meg*2*pi)
>>>>>> SYMBOL res -48 80 R90
>>>>>> WINDOW 0 0 56 VBottom 2
>>>>>> WINDOW 3 32 56 VTop 2
>>>>>> SYMATTR InstName R2
>>>>>> SYMATTR Value 1
>>>>>> TEXT 72 0 Left 2 !.tran 5m
>>>>>> TEXT 0 112 Left 2 !K12 L1 L2 1u
>>>>>> TEXT -152 0 Left 2 ;Transmitter
>>>>>> TEXT 264 0 Left 2 ;Crystal set receiver
>>>>>
>>>>> Suggestions:
>>>>>
>>>>> Reduce the modulation a bit. It distorts at 100%.
>>>>>
>>>>> Make R1 2K, like an old dynamic headphone.
>>>>>
>>>>> Change the coupling to 50u. A good antenna makes a lot of signal.
>>>>>
>>>>> You can use a BAT54 schottky.
>>>>>
>>>>
>>>>
>>>>You don't expect high fidelity from a crystal set, but OK, fair enough.
>>>>C2 was meant to model a piezo earbud. I should actually measure one...
>>>>
>>>>I got the values of C! and L1 wrong. C1=300pF is more reasonable,
>>>>and then L1=84.43uH. In practice, of course, C1 would be tuned and L1
>>>>would be fixed at 80uH or so, but either way works.
>>>>
>>>>The voltage of B1 and the tranformer coupling factor are just guesses,
>>>>based on the knwoledge that crystal sets actually do work.
>>>>
>>>>Jeroen Belleman
>>>
>>>I think that most xtal sets do some sort of impedance matching from
>>>the antenna up into the main coil, taps on the coil or an extra
>>>winding. A really longwire antanna will have a lot of capacitance and
>>>an equivalent lowish impedance.
>>>
>>>The people who have made xtal sets over the last century or so don't
>>>seem to have been very quantitative.
>>>
>>>I've wondered if I can slurp enought power out of the air to light an
>>>LED. My office is in a wooden building about 3 miles from Sutro Tower.
>>>Castro valley is a bowl that I suspect focusses the RF onto us.
>>
>>LEDs require relatively large amounts of current, so I don't see how
>>that would be possible, John. There's only *one* bloke I can think of
>>who could conceivably pull that off and he's long dead, sadly.
>>Edison's nemesis:
>>
>>https://en.wikipedia.org/wiki/Nikola_Tesla
>
>A good LED is visible in typical room light at 1 uA, which would be
>about 2 uW. I'd imagine that a modest antenna and a decent detector
>could do much better than that.
>
>The difference between a crystal set and lighting an LED is that the
>LED case should use the entire spectrum, AM TV FM, which is densely
>packed where I am. That would take some thinking.
>

On Sunday, February 11, 2024 at 11:35:00 AM UTC-8, Cursitor Doom wrote:
> On Sun, 11 Feb 2024 10:32:32 -0800, John Larkin <j...@997PotHill.com>
> wrote:

> >>>I've wondered if I can slurp enought power out of the air to light an
> >>>LED. My office is in a wooden building about 3 miles from Sutro Tower.
> >>>Castro valley is a bowl that I suspect focusses the RF onto us.
> >>
> >>LEDs require relatively large amounts of current, so I don't see how
> >>that would be possible, John. There's only *one* bloke I can think of
> >>who could conceivably pull that off and he's long dead, sadly.
> >>Edison's nemesis:
> >>
> >>https://en.wikipedia.org/wiki/Nikola_Tesla
> >
> >A good LED is visible in typical room light at 1 uA, which would be
> >about 2 uW. I'd imagine that a modest antenna and a decent detector
> >could do much better than that.
> >
> >The difference between a crystal set and lighting an LED is that the
> >LED case should use the entire spectrum, AM TV FM, which is densely
> >packed where I am. That would take some thinking.
> >
> Neon or similar would be far more easily achievable I reckon.

A neon lamp has negative resistance; it'd blink if you could get the voltage
high enough against rectifier leakage.

Easiest way to get a photon or five would be with antenna-and-tuning,
so would be filtering to a single input carrier frequency; TV station
would be the old-school answer, but they're in the UHF (tricky,
because the tuning requires you to wind a UHF inductor) so
the next-best is AM broadcast receiver.

Absolute easiest, is if a neighbor has a SW station; one of mine had a nice
tower antenna (and I had TV reception for nearly 100 miles because I
could aim a Yagi at his tower and get a bounce from over-the-horizon).
OK, maybe inductive coupling to 60 Hz in power-on-poles would
be easier, but also... slightly illegal.

Instead of creating a dedicated antenna, one could inductively clamp on
a few places, maybe your floor lamp unswitched (neutral) wire is worth
untangling for test purposes.

On Sun, 11 Feb 2024 19:34:53 +0000, Cursitor Doom <cd@notformail.com>
wrote:

>On Sun, 11 Feb 2024 10:32:32 -0800, John Larkin <jl@997PotHill.com>
>wrote:
>
>>On Sun, 11 Feb 2024 17:40:10 +0000, Cursitor Doom <cd@notformail.com>
>>wrote:
>>
>>>On Sun, 11 Feb 2024 07:28:39 -0800, John Larkin <jl@997PotHill.com>
>>>wrote:
>>>
>>>>On Sun, 11 Feb 2024 10:39:49 +0100, Jeroen Belleman
>>>><jeroen@nospam.please> wrote:
>>>>
>>>>>On 2/11/24 02:22, John Larkin wrote:
>>>>>> On Sat, 10 Feb 2024 22:33:15 +0100, Jeroen Belleman
>>>>>> <jeroen@nospam.please> wrote:
>>>>>>
>>>>>>> On 2/10/24 18:27, Don wrote:
>>>>>>>> Jeroen Belleman wrote:
>>>>>>>>> Don wrote:
>>>>>>>>>> Jan Panteltje wrote:
>>>>>>>>>>> John Larkin wrote:
>>>>>>>>>>>> Cursitor Doom wrote:
>>>>>>>>>>>>> John Larkin wrote:
>>>>>>>>>>>>>> Fred Bloggs wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> This is the new circuit analysis: exploring operation in Spice and looking at graphs.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> https://www.elektormagazine.com/articles/circuit-analysis-with-ltspice-12v-lamp-flasher
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Too much talking for too little circuit.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Mr. Bloggs had to use LTspice for a 12V lamp flasher?? Jeez!
>>>>>>>>>>>>
>>>>>>>>>>>> Using Spice is reasonable, easier than computing exponentials by hand.
>>>>>>>>>>>> I use Spice for voltage dividers, filters, rectifiers, RLC delays, all
>>>>>>>>>>>> sorts of stuff.
>>>>>>>>>>>
>>>>>>>>>>> I mostly use pepper, Chili and salt as spices, some sugar etc.
>>>>>>>>>>> If this spice stuff continues people will need it before throwing a ball...
>>>>>>>>>>> Why not just ask AI to design the circuit for you,?
>>>>>>>>>>>
>>>>>>>>>>> And no guarantee that anything in LTspice works -in- or even resembles reality!
>>>>>>>>>>>
>>>>>>>>>>> Real hands on testing is needed to get a clue.
>>>>>>>>>>
>>>>>>>>>> Tis true the Spice won't help you
>>>>>>>>>> With a simple radio set:
>>>>>>>>>>
>>>>>>>>>> <https://crcomp.net/crystalrx/a.png>
>>>>>>>>>> [...]
>>>>>>>>>
>>>>>>>>> Why not?
>>>>>>>>
>>>>>>>> Good question. And, with all due respect, you ought to post some Spice to
>>>>>>>> show me how you do it.
>>>>>>>>
>>>>>>>> Danke,
>>>>>>>>
>>>>>>>
>>>>>>> Something akin to this.
>>>>>>>
>>>>>>> Jeroen Belleman
>>>>>>>
>>>>>>> ================================================
>>>>>>> Version 4
>>>>>>> SHEET 1 880 680
>>>>>>> WIRE -144 96 -176 96
>>>>>>> WIRE -32 96 -64 96
>>>>>>> WIRE 272 96 176 96
>>>>>>> WIRE 352 96 272 96
>>>>>>> WIRE 464 96 416 96
>>>>>>> WIRE 512 96 464 96
>>>>>>> WIRE 544 96 512 96
>>>>>>> WIRE -176 128 -176 96
>>>>>>> WIRE -32 128 -32 96
>>>>>>> WIRE 176 128 176 96
>>>>>>> WIRE 272 128 272 96
>>>>>>> WIRE 464 128 464 96
>>>>>>> WIRE 544 144 544 96
>>>>>>> WIRE -176 240 -176 208
>>>>>>> WIRE -32 240 -32 208
>>>>>>> WIRE 176 240 176 208
>>>>>>> WIRE 272 240 272 192
>>>>>>> WIRE 464 240 464 208
>>>>>>> WIRE 544 240 544 208
>>>>>>> FLAG 176 240 0
>>>>>>> FLAG 272 240 0
>>>>>>> FLAG 464 240 0
>>>>>>> FLAG 544 240 0
>>>>>>> FLAG -32 240 0
>>>>>>> FLAG -176 240 0
>>>>>>> FLAG 512 96 out
>>>>>>> SYMBOL ind2 160 112 R0
>>>>>>> SYMATTR InstName L1
>>>>>>> SYMATTR Value 16µ
>>>>>>> SYMATTR Type ind
>>>>>>> SYMBOL cap 256 128 R0
>>>>>>> SYMATTR InstName C1
>>>>>>> SYMATTR Value 6.28n
>>>>>>> SYMBOL diode 352 112 R270
>>>>>>> WINDOW 0 32 32 VTop 2
>>>>>>> WINDOW 3 0 32 VBottom 2
>>>>>>> SYMATTR InstName D1
>>>>>>> SYMATTR Value AA112
>>>>>>> SYMBOL res 448 112 R0
>>>>>>> SYMATTR InstName R1
>>>>>>> SYMATTR Value 1meg
>>>>>>> SYMBOL cap 528 144 R0
>>>>>>> SYMATTR InstName C2
>>>>>>> SYMATTR Value 10n
>>>>>>> SYMBOL ind2 -48 112 R0
>>>>>>> SYMATTR InstName L2
>>>>>>> SYMATTR Value 16µ
>>>>>>> SYMATTR Type ind
>>>>>>> SYMBOL bv -176 112 R0
>>>>>>> WINDOW 3 -186 181 Left 2
>>>>>>> SYMATTR InstName B1
>>>>>>> SYMATTR Value V=10k*(1+sin(time*1k*2*pi))*sin(time*1meg*2*pi)
>>>>>>> SYMBOL res -48 80 R90
>>>>>>> WINDOW 0 0 56 VBottom 2
>>>>>>> WINDOW 3 32 56 VTop 2
>>>>>>> SYMATTR InstName R2
>>>>>>> SYMATTR Value 1
>>>>>>> TEXT 72 0 Left 2 !.tran 5m
>>>>>>> TEXT 0 112 Left 2 !K12 L1 L2 1u
>>>>>>> TEXT -152 0 Left 2 ;Transmitter
>>>>>>> TEXT 264 0 Left 2 ;Crystal set receiver
>>>>>>
>>>>>> Suggestions:
>>>>>>
>>>>>> Reduce the modulation a bit. It distorts at 100%.
>>>>>>
>>>>>> Make R1 2K, like an old dynamic headphone.
>>>>>>
>>>>>> Change the coupling to 50u. A good antenna makes a lot of signal.
>>>>>>
>>>>>> You can use a BAT54 schottky.
>>>>>>
>>>>>
>>>>>
>>>>>You don't expect high fidelity from a crystal set, but OK, fair enough.
>>>>>C2 was meant to model a piezo earbud. I should actually measure one...
>>>>>
>>>>>I got the values of C! and L1 wrong. C1=300pF is more reasonable,
>>>>>and then L1=84.43uH. In practice, of course, C1 would be tuned and L1
>>>>>would be fixed at 80uH or so, but either way works.
>>>>>
>>>>>The voltage of B1 and the tranformer coupling factor are just guesses,
>>>>>based on the knwoledge that crystal sets actually do work.
>>>>>
>>>>>Jeroen Belleman
>>>>
>>>>I think that most xtal sets do some sort of impedance matching from
>>>>the antenna up into the main coil, taps on the coil or an extra
>>>>winding. A really longwire antanna will have a lot of capacitance and
>>>>an equivalent lowish impedance.
>>>>
>>>>The people who have made xtal sets over the last century or so don't
>>>>seem to have been very quantitative.
>>>>
>>>>I've wondered if I can slurp enought power out of the air to light an
>>>>LED. My office is in a wooden building about 3 miles from Sutro Tower.
>>>>Castro valley is a bowl that I suspect focusses the RF onto us.
>>>
>>>LEDs require relatively large amounts of current, so I don't see how
>>>that would be possible, John. There's only *one* bloke I can think of
>>>who could conceivably pull that off and he's long dead, sadly.
>>>Edison's nemesis:
>>>
>>>https://en.wikipedia.org/wiki/Nikola_Tesla
>>
>>A good LED is visible in typical room light at 1 uA, which would be
>>about 2 uW. I'd imagine that a modest antenna and a decent detector
>>could do much better than that.
>>
>>The difference between a crystal set and lighting an LED is that the
>>LED case should use the entire spectrum, AM TV FM, which is densely
>>packed where I am. That would take some thinking.
>>
>
>Neon or similar would be far more easily achievable I reckon.

On Sun, 11 Feb 2024 12:35:14 -0800 (PST), whit3rd <whit3rd@gmail.com>
wrote:

>On Sunday, February 11, 2024 at 11:35:00?AM UTC-8, Cursitor Doom wrote:
>> On Sun, 11 Feb 2024 10:32:32 -0800, John Larkin <j...@997PotHill.com>
>> wrote:
>
>> >>>I've wondered if I can slurp enought power out of the air to light an
>> >>>LED. My office is in a wooden building about 3 miles from Sutro Tower.
>> >>>Castro valley is a bowl that I suspect focusses the RF onto us.
>> >>
>> >>LEDs require relatively large amounts of current, so I don't see how
>> >>that would be possible, John. There's only *one* bloke I can think of
>> >>who could conceivably pull that off and he's long dead, sadly.
>> >>Edison's nemesis:
>> >>
>> >>https://en.wikipedia.org/wiki/Nikola_Tesla
>> >
>> >A good LED is visible in typical room light at 1 uA, which would be
>> >about 2 uW. I'd imagine that a modest antenna and a decent detector
>> >could do much better than that.
>> >
>> >The difference between a crystal set and lighting an LED is that the
>> >LED case should use the entire spectrum, AM TV FM, which is densely
>> >packed where I am. That would take some thinking.
>> >
>> Neon or similar would be far more easily achievable I reckon.
>
>A neon lamp has negative resistance; it'd blink if you could get the voltage
>high enough against rectifier leakage.
>
>Easiest way to get a photon or five would be with antenna-and-tuning,
>so would be filtering to a single input carrier frequency; TV station
>would be the old-school answer, but they're in the UHF (tricky,
>because the tuning requires you to wind a UHF inductor) so
>the next-best is AM broadcast receiver.

Somewhere I still have an old timey wavemeter that works off this
principle. When tuned to the same frequency as a nearby transmitter,
the bulb lights. Amazing how far we've come in 100 years.

On a sunny day (Sun, 11 Feb 2024 17:40:10 +0000) it happened Cursitor Doom
<cd@notformail.com> wrote in <je1isittughq4f5kai705kqvgjk61ei4vl@4ax.com>:

>On Sun, 11 Feb 2024 07:28:39 -0800, John Larkin <jl@997PotHill.com>
>wrote:
>>I've wondered if I can slurp enought power out of the air to light an
>>LED. My office is in a wooden building about 3 miles from Sutro Tower.
>>Castro valley is a bowl that I suspect focusses the RF onto us.
>
>LEDs require relatively large amounts of current, so I don't see how
>that would be possible, John. There's only *one* bloke I can think of
>who could conceivably pull that off and he's long dead, sadly.
>Edison's nemesis:
>
>https://en.wikipedia.org/wiki/Nikola_Tesla

Many years ago I tried a LED on my 27 MHz GPA antenna,
It did light up when my cross the street neighbor transmitted with his set.
I asked him how much power he used,
did not get an answer, 4 W was the legal limit back then IIRC,
some Italians on that band used hundreds of watts.

On a sunny day (Sun, 11 Feb 2024 19:34:53 +0000) it happened Cursitor Doom
<cd@notformail.com> wrote in <698isip5rgse0iu677d5u12m92puoqokaf@4ax.com>:

>On Sun, 11 Feb 2024 10:32:32 -0800, John Larkin <jl@997PotHill.com>
>wrote:
>
>>On Sun, 11 Feb 2024 17:40:10 +0000, Cursitor Doom <cd@notformail.com>
>>wrote:
>>
>>>On Sun, 11 Feb 2024 07:28:39 -0800, John Larkin <jl@997PotHill.com>
>>>wrote:
>>>
>>>>On Sun, 11 Feb 2024 10:39:49 +0100, Jeroen Belleman
>>>><jeroen@nospam.please> wrote:
>>>>
>>>>>On 2/11/24 02:22, John Larkin wrote:
>>>>>> On Sat, 10 Feb 2024 22:33:15 +0100, Jeroen Belleman
>>>>>> <jeroen@nospam.please> wrote:
>>>>>>
>>>>>>> On 2/10/24 18:27, Don wrote:
>>>>>>>> Jeroen Belleman wrote:
>>>>>>>>> Don wrote:
>>>>>>>>>> Jan Panteltje wrote:
>>>>>>>>>>> John Larkin wrote:
>>>>>>>>>>>> Cursitor Doom wrote:
>>>>>>>>>>>>> John Larkin wrote:
>>>>>>>>>>>>>> Fred Bloggs wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> This is the new circuit analysis: exploring operation in Spice and looking at graphs.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> https://www.elektormagazine.com/articles/circuit-analysis-with-ltspice-12v-lamp-flasher
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Too much talking for too little circuit.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Mr. Bloggs had to use LTspice for a 12V lamp flasher?? Jeez!
>>>>>>>>>>>>
>>>>>>>>>>>> Using Spice is reasonable, easier than computing exponentials by hand.
>>>>>>>>>>>> I use Spice for voltage dividers, filters, rectifiers, RLC delays, all
>>>>>>>>>>>> sorts of stuff.
>>>>>>>>>>>
>>>>>>>>>>> I mostly use pepper, Chili and salt as spices, some sugar etc.
>>>>>>>>>>> If this spice stuff continues people will need it before throwing a ball...
>>>>>>>>>>> Why not just ask AI to design the circuit for you,?
>>>>>>>>>>>
>>>>>>>>>>> And no guarantee that anything in LTspice works -in- or even resembles reality!
>>>>>>>>>>>
>>>>>>>>>>> Real hands on testing is needed to get a clue.
>>>>>>>>>>
>>>>>>>>>> Tis true the Spice won't help you
>>>>>>>>>> With a simple radio set:
>>>>>>>>>>
>>>>>>>>>> <https://crcomp.net/crystalrx/a.png>
>>>>>>>>>> [...]
>>>>>>>>>
>>>>>>>>> Why not?
>>>>>>>>
>>>>>>>> Good question. And, with all due respect, you ought to post some Spice to
>>>>>>>> show me how you do it.
>>>>>>>>
>>>>>>>> Danke,
>>>>>>>>
>>>>>>>
>>>>>>> Something akin to this.
>>>>>>>
>>>>>>> Jeroen Belleman
>>>>>>>
>>>>>>> ================================================
>>>>>>> Version 4
>>>>>>> SHEET 1 880 680
>>>>>>> WIRE -144 96 -176 96
>>>>>>> WIRE -32 96 -64 96
>>>>>>> WIRE 272 96 176 96
>>>>>>> WIRE 352 96 272 96
>>>>>>> WIRE 464 96 416 96
>>>>>>> WIRE 512 96 464 96
>>>>>>> WIRE 544 96 512 96
>>>>>>> WIRE -176 128 -176 96
>>>>>>> WIRE -32 128 -32 96
>>>>>>> WIRE 176 128 176 96
>>>>>>> WIRE 272 128 272 96
>>>>>>> WIRE 464 128 464 96
>>>>>>> WIRE 544 144 544 96
>>>>>>> WIRE -176 240 -176 208
>>>>>>> WIRE -32 240 -32 208
>>>>>>> WIRE 176 240 176 208
>>>>>>> WIRE 272 240 272 192
>>>>>>> WIRE 464 240 464 208
>>>>>>> WIRE 544 240 544 208
>>>>>>> FLAG 176 240 0
>>>>>>> FLAG 272 240 0
>>>>>>> FLAG 464 240 0
>>>>>>> FLAG 544 240 0
>>>>>>> FLAG -32 240 0
>>>>>>> FLAG -176 240 0
>>>>>>> FLAG 512 96 out
>>>>>>> SYMBOL ind2 160 112 R0
>>>>>>> SYMATTR InstName L1
>>>>>>> SYMATTR Value 16�
>>>>>>> SYMATTR Type ind
>>>>>>> SYMBOL cap 256 128 R0
>>>>>>> SYMATTR InstName C1
>>>>>>> SYMATTR Value 6.28n
>>>>>>> SYMBOL diode 352 112 R270
>>>>>>> WINDOW 0 32 32 VTop 2
>>>>>>> WINDOW 3 0 32 VBottom 2
>>>>>>> SYMATTR InstName D1
>>>>>>> SYMATTR Value AA112
>>>>>>> SYMBOL res 448 112 R0
>>>>>>> SYMATTR InstName R1
>>>>>>> SYMATTR Value 1meg
>>>>>>> SYMBOL cap 528 144 R0
>>>>>>> SYMATTR InstName C2
>>>>>>> SYMATTR Value 10n
>>>>>>> SYMBOL ind2 -48 112 R0
>>>>>>> SYMATTR InstName L2
>>>>>>> SYMATTR Value 16�
>>>>>>> SYMATTR Type ind
>>>>>>> SYMBOL bv -176 112 R0
>>>>>>> WINDOW 3 -186 181 Left 2
>>>>>>> SYMATTR InstName B1
>>>>>>> SYMATTR Value V=10k*(1+sin(time*1k*2*pi))*sin(time*1meg*2*pi)
>>>>>>> SYMBOL res -48 80 R90
>>>>>>> WINDOW 0 0 56 VBottom 2
>>>>>>> WINDOW 3 32 56 VTop 2
>>>>>>> SYMATTR InstName R2
>>>>>>> SYMATTR Value 1
>>>>>>> TEXT 72 0 Left 2 !.tran 5m
>>>>>>> TEXT 0 112 Left 2 !K12 L1 L2 1u
>>>>>>> TEXT -152 0 Left 2 ;Transmitter
>>>>>>> TEXT 264 0 Left 2 ;Crystal set receiver
>>>>>>
>>>>>> Suggestions:
>>>>>>
>>>>>> Reduce the modulation a bit. It distorts at 100%.
>>>>>>
>>>>>> Make R1 2K, like an old dynamic headphone.
>>>>>>
>>>>>> Change the coupling to 50u. A good antenna makes a lot of signal.
>>>>>>
>>>>>> You can use a BAT54 schottky.
>>>>>>
>>>>>
>>>>>
>>>>>You don't expect high fidelity from a crystal set, but OK, fair enough.
>>>>>C2 was meant to model a piezo earbud. I should actually measure one...
>>>>>
>>>>>I got the values of C! and L1 wrong. C1=300pF is more reasonable,
>>>>>and then L1=84.43uH. In practice, of course, C1 would be tuned and L1
>>>>>would be fixed at 80uH or so, but either way works.
>>>>>
>>>>>The voltage of B1 and the tranformer coupling factor are just guesses,
>>>>>based on the knwoledge that crystal sets actually do work.
>>>>>
>>>>>Jeroen Belleman
>>>>
>>>>I think that most xtal sets do some sort of impedance matching from
>>>>the antenna up into the main coil, taps on the coil or an extra
>>>>winding. A really longwire antanna will have a lot of capacitance and
>>>>an equivalent lowish impedance.
>>>>
>>>>The people who have made xtal sets over the last century or so don't
>>>>seem to have been very quantitative.
>>>>
>>>>I've wondered if I can slurp enought power out of the air to light an
>>>>LED. My office is in a wooden building about 3 miles from Sutro Tower.
>>>>Castro valley is a bowl that I suspect focusses the RF onto us.
>>>
>>>LEDs require relatively large amounts of current, so I don't see how
>>>that would be possible, John. There's only *one* bloke I can think of
>>>who could conceivably pull that off and he's long dead, sadly.
>>>Edison's nemesis:
>>>
>>>https://en.wikipedia.org/wiki/Nikola_Tesla
>>
>>A good LED is visible in typical room light at 1 uA, which would be
>>about 2 uW. I'd imagine that a modest antenna and a decent detector
>>could do much better than that.
>>
>>The difference between a crystal set and lighting an LED is that the
>>LED case should use the entire spectrum, AM TV FM, which is densely
>>packed where I am. That would take some thinking.
>>
>
>Neon or similar would be far more easily achievable I reckon.

Arie de Muijnck wrote:
> Cursitor Doom wrote:
>> John Larkin wrote:
>>> Don wrote:
>>>> Jan Panteltje wrote:
>>>>> John Larkin wrote:
>>>>>> Cursitor Doom wrote:
>>>>>>> John Larkin wrote:
>>>>>>>> Fred Bloggs wrote:
>>>>>>>>
>>>>>>>>> This is the new circuit analysis: exploring operation in Spice and looking at graphs.
>>>>>>>>>
>>>>>>>>> https://www.elektormagazine.com/articles/circuit-analysis-with-ltspice-12v-lamp-flasher
>>>>>>>>
>>>>>>>> Too much talking for too little circuit.
>>>>>>>
>>>>>>> Mr. Bloggs had to use LTspice for a 12V lamp flasher?? Jeez!
>>>>>>
>>>>>> Using Spice is reasonable, easier than computing exponentials by hand.
>>>>>> I use Spice for voltage dividers, filters, rectifiers, RLC delays, all
>>>>>> sorts of stuff.
>>>>>
>>>>> I mostly use pepper, Chili and salt as spices, some sugar etc.
>>>>> If this spice stuff continues people will need it before throwing a ball...
>>>>> Why not just ask AI to design the circuit for you,?
>>>>>
>>>>> And no guarantee that anything in LTspice works -in- or even resembles reality!
>>>>>
>>>>> Real hands on testing is needed to get a clue.
>>>>
>>>> Tis true the Spice won't help you
>>>> With a simple radio set:
>>>>
>>>> <https://crcomp.net/crystalrx/a.png>
>>>> <https://crcomp.net/crystalrx/b.png>
>>>>
>>>> No worries all's not nyet
>>>> Spice fiddling's a safe bet...
>>>
>>> Why does a crystal set need a power supply?
>>>
>>> I don't think the circuit will work with a crystal headphone.
>>
>> It wouldn't work without one. Xtal sets need hi-z earphones for
>> obvious reasons and crystal earpieces are ideal.
>
> Yes, but they need a leakage resistor over the earpiece so the diode kan
> stay doing its work. A pencil stripe will do.
> Just as the inductive earpiece needs a parallel capacitor for optimal work
> (often the wiring functions as such).

The crystal cult concurs with your circumspect constructive criticism:

<http://techlib.com/electronics/crystal.html>

It turns out a 0.001 uF cap and an 82 k resistor in parallel with the
earphone increases amplitude perceptibly. Thank you for sharing.

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

John Larkin wrote:
> Don wrote:
>>John Larkin wrote:
>>> Cursitor Doom wrote:
>>>>John Larkin wrote:
>>>>> Don wrote:
>>>>>>Jan Panteltje wrote:
>>>>>>> John Larkin wrote:
>>>>>>>> Cursitor Doom wrote:
>>>>>>>>> John Larkin wrote:
>>>>>>>>>> Fred Bloggs wrote:
>>>>>>>>>>
>>>>>>>>>>>This is the new circuit analysis: exploring operation in Spice and looking at graphs.
>>>>>>>>>>>
>>>>>>>>>>>https://www.elektormagazine.com/articles/circuit-analysis-with-ltspice-12v-lamp-flasher
>>>>>>>>>>
>>>>>>>>>>Too much talking for too little circuit.
>>>>>>>>>
>>>>>>>>>Mr. Bloggs had to use LTspice for a 12V lamp flasher?? Jeez!
>>>>>>>>
>>>>>>>>Using Spice is reasonable, easier than computing exponentials by hand.
>>>>>>>>I use Spice for voltage dividers, filters, rectifiers, RLC delays, all
>>>>>>>>sorts of stuff.
>>>>>>>
>>>>>>> I mostly use pepper, Chili and salt as spices, some sugar etc.
>>>>>>> If this spice stuff continues people will need it before throwing a ball ...
>>>>>>> Why not just ask AI to design the circuit for you,?
>>>>>>>
>>>>>>> And no guarantee that anything in LTspice works -in- or even resembles reality!
>>>>>>>
>>>>>>> Real hands on testing is needed to get a clue.
>>>>>>
>>>>>>Tis true the Spice won't help you
>>>>>>With a simple radio set:
>>>>>>
>>>>>><https://crcomp.net/crystalrx/a.png>
>>>>>><https://crcomp.net/crystalrx/b.png>
>>>>>>
>>>>>>No worries all's not nyet
>>>>>>Spice fiddling's a safe bet...
>>>>>
>>>>>Why does a crystal set need a power supply?
>>>>>
>>>>>I don't think the circuit will work with a crystal headphone.
>>>>
>>>>It wouldn't work without one. Xtal sets need hi-z earphones for
>>>>obvious reasons and crystal earpieces are ideal.
>>>
>>> In the circuit shown, the headphone capacitance will charge up and the
>>> diode will back-bias.
>>>
>>> Unless you use a very leaky diode.
>>>
>>> What's the power supply for?
>>
>>Good question. Although it primary provides power for future, yet-to-be
>>developed protos, it also fulfills a fundamental function for a crystal
>>radio set.
>>
>>Think about it.
>
> I can't imagine why.
>>
>>Hint: the power cord conveniently connects three cables to the case, but
>>not all are used by this crystal circuit.

A good crystal set needs to squeeze as much precious power as possible
out of a radio wave. A solid connection to ground fulfills a fundamental
function - it firmly anchors the signal. The NEMA ground cable provides
a handy ground connection, even though the power supply remains unused.

Anyhow, now's the time to put the previously passive power supply to
good use. It's possible to eliminate the earphone with an electronic
precision voltage reference:

<http://techlib.com/electronics/graphics/xtal431.gif>

# # #

World Radio Day – February 13, 2024
<https://nationaltoday.com/world-radio-day/>

Radio: A century informing, entertaining and educating
<https://www.unesco.org/en/days/world-radio/radio-next-century>

World Radio Day 2024: How Kenya’s Community Radios are Strengthening Democracy
<https://www.unesco.org/en/articles/world-radio-day-2024-how-kenyas-community-radios-are-strengthening-democracy>

World Radio Day 2024: Theme, History, Significance & Everything Else You Must Know
<https://www.freepressjournal.in/lifestyle/world-radio-day-2024-theme-history-significance-everything-you-must-know-about>

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

On Monday, February 12, 2024 at 4:40:18 AM UTC+11, Cursitor Doom wrote:
> On Sun, 11 Feb 2024 07:28:39 -0800, John Larkin <j...@997PotHill.com> wrote:
> >On Sun, 11 Feb 2024 10:39:49 +0100, Jeroen Belleman <jer...@nospam.please> wrote:
> >>On 2/11/24 02:22, John Larkin wrote:
> >>> On Sat, 10 Feb 2024 22:33:15 +0100, Jeroen Belleman <jer...@nospam.please> wrote:
> >>>> On 2/10/24 18:27, Don wrote:
> >>>>> Jeroen Belleman wrote:
> >>>>>> Don wrote:
> >>>>>>> Jan Panteltje wrote:
> >>>>>>>> John Larkin wrote:
> >>>>>>>>> Cursitor Doom wrote:
> >>>>>>>>>> John Larkin wrote:
> >>>>>>>>>>> Fred Bloggs wrote:

> >I've wondered if I can slurp enought power out of the air to light an
> >LED. My office is in a wooden building about 3 miles from Sutro Tower.
> >Castro valley is a bowl that I suspect focusses the RF onto us.
>
> LEDs require relatively large amounts of current, so I don't see how
> that would be possible, John. There's only *one* bloke I can think of
> who could conceivably pull that off and he's long dead, sadly.
> Edison's nemesis:
>
> https://en.wikipedia.org/wiki/Nikola_Tesla

That's pure ignorance talking. If you are close to a transmitter you can collect a lot of power.

People who lived close to the Droitwich transmitter in the UK

https://en.wikipedia.org/wiki/Droitwich_Transmitting_Station

were legally obliged to shield their fluorescent lamps with coarse wire mesh (chicken wire) shields.

Without the shield the lamps would run continuously, soaking up up the expensively transmitted power and providing free lighting.

--
Bill Sloman, Sydney

On a sunny day (Wed, 14 Feb 2024 00:43:48 -0000 (UTC)) it happened "Don"
<g@crcomp.net> wrote in <20240213a@crcomp.net>:

>A good crystal set needs to squeeze as much precious power as possible
>out of a radio wave. A solid connection to ground fulfills a fundamental
>function - it firmly anchors the signal. The NEMA ground cable provides
>a handy ground connection, even though the power supply remains unused.

I had crystal portable radio back then
it used a moving ferrite rod in a coil for tuning and antenna,
took it with me on long walks.

Most AM long wave to medium wave radios use a ferrite rod, but with a tuning cap.
Amazing how much signal such a -magnetic- antenna delivers,
sensitive to direction though.

Jan Panteltje wrote:
> Don wrote:
>
>>A good crystal set needs to squeeze as much precious power as possible
>>out of a radio wave. A solid connection to ground fulfills a fundamental
>>function - it firmly anchors the signal. The NEMA ground cable provides
>>a handy ground connection, even though the power supply remains unused.
>
> I had crystal portable radio back then
> it used a moving ferrite rod in a coil for tuning and antenna,
> took it with me on long walks.
>
> Most AM long wave to medium wave radios use a ferrite rod, but with a tuning cap.
> Amazing how much signal such a -magnetic- antenna delivers,
> sensitive to direction though.

Potato guns aside, the last rocket launched by me happened a long time
ago. If another small rocket is ever again launched by me it may carry
a crystal radio:

<https://crystalradio.net/misc/rocket/index.shtml>

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

Don wrote:
> Jan Panteltje wrote:
>> Don wrote:
>>
>>>A good crystal set needs to squeeze as much precious power as possible
>>>out of a radio wave. A solid connection to ground fulfills a fundamental
>>>function - it firmly anchors the signal. The NEMA ground cable provides
>>>a handy ground connection, even though the power supply remains unused.
>>
>> I had crystal portable radio back then
>> it used a moving ferrite rod in a coil for tuning and antenna,
>> took it with me on long walks.
>>
>> Most AM long wave to medium wave radios use a ferrite rod, but with a tuning
cap.
>> Amazing how much signal such a -magnetic- antenna delivers,
>> sensitive to direction though.
>
> Potato guns aside, the last rocket launched by me happened a long time
> ago. If another small rocket is ever again launched by me it may carry
> a crystal radio:
>
> <https://crystalradio.net/misc/rocket/index.shtml>

Government inflation drove up a rocket radio's price 7,200% since the 1950s:

<https://www.ebay.com/itm/276326468516>

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

On a sunny day (Wed, 14 Feb 2024 15:40:16 -0000 (UTC)) it happened "Don"
<g@crcomp.net> wrote in <20240214a@crcomp.net>:

>Jan Panteltje wrote:
>> Don wrote:
>>
>>>A good crystal set needs to squeeze as much precious power as possible
>>>out of a radio wave. A solid connection to ground fulfills a fundamental
>>>function - it firmly anchors the signal. The NEMA ground cable provides
>>>a handy ground connection, even though the power supply remains unused.
>>
>> I had crystal portable radio back then
>> it used a moving ferrite rod in a coil for tuning and antenna,
>> took it with me on long walks.
>>
>> Most AM long wave to medium wave radios use a ferrite rod, but with a tuning cap.
>> Amazing how much signal such a -magnetic- antenna delivers,
>> sensitive to direction though.
>
>Potato guns aside, the last rocket launched by me happened a long time
>ago. If another small rocket is ever again launched by me it may carry
>a crystal radio:
>
><https://crystalradio.net/misc/rocket/index.shtml>

Yes that is the one!

Jan Panteltje wrote:
> Don wrote:
>>Jan Panteltje wrote:
>>> Don wrote:
>>>
>>>>A good crystal set needs to squeeze as much precious power as possible
>>>>out of a radio wave. A solid connection to ground fulfills a fundamental
>>>>function - it firmly anchors the signal. The NEMA ground cable provides
>>>>a handy ground connection, even though the power supply remains unused.
>>>
>>> I had crystal portable radio back then
>>> it used a moving ferrite rod in a coil for tuning and antenna,
>>> took it with me on long walks.
>>>
>>> Most AM long wave to medium wave radios use a ferrite rod, but with a tuning cap.
>>> Amazing how much signal such a -magnetic- antenna delivers,
>>> sensitive to direction though.
>>
>>Potato guns aside, the last rocket launched by me happened a long time
>>ago. If another small rocket is ever again launched by me it may carry
>>a crystal radio:
>>
>><https://crystalradio.net/misc/rocket/index.shtml>
>
> Yes that is the one!

The TL431 needs to be repurposed into a power supply before my crystal
set can accommodate another adornment: an audio amp in the form of a
LM386. It turns out the power supply in my "bone yard" chassis supplies
only 5 VDC.

So a simple SMPS, similar to the flyback converter Win Hill reversed
engineered for Figure 9.74 in _Art of the Electronics_, needs to be
prototyped:

<https://archive.org/details/the-art-of-electronics-3rd-ed-2015_202008/page/657/mode/2up>

Applications found in both the CSC72XX and UC3843 datasheets also fit the
bill.

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

On a sunny day (Thu, 15 Feb 2024 15:40:07 -0000 (UTC)) it happened "Don"
<g@crcomp.net> wrote in <20240215a@crcomp.net>:

>Jan Panteltje wrote:
>> Don wrote:
>>>Jan Panteltje wrote:
>>>> Don wrote:
>>>>
>>>>>A good crystal set needs to squeeze as much precious power as possible
>>>>>out of a radio wave. A solid connection to ground fulfills a fundamental
>>>>>function - it firmly anchors the signal. The NEMA ground cable provides
>>>>>a handy ground connection, even though the power supply remains unused.
>>>>
>>>> I had crystal portable radio back then
>>>> it used a moving ferrite rod in a coil for tuning and antenna,
>>>> took it with me on long walks.
>>>>
>>>> Most AM long wave to medium wave radios use a ferrite rod, but with a tuning cap.
>>>> Amazing how much signal such a -magnetic- antenna delivers,
>>>> sensitive to direction though.
>>>
>>>Potato guns aside, the last rocket launched by me happened a long time
>>>ago. If another small rocket is ever again launched by me it may carry
>>>a crystal radio:
>>>
>>><https://crystalradio.net/misc/rocket/index.shtml>
>>
>> Yes that is the one!
>
>The TL431 needs to be repurposed into a power supply before my crystal
>set can accommodate another adornment: an audio amp in the form of a
>LM386. It turns out the power supply in my "bone yard" chassis supplies
>only 5 VDC.
>
>So a simple SMPS, similar to the flyback converter Win Hill reversed
>engineered for Figure 9.74 in _Art of the Electronics_, needs to be
>prototyped:
>
><https://archive.org/details/the-art-of-electronics-3rd-ed-2015_202008/page/657/mode/2up>
>
>Applications found in both the CSC72XX and UC3843 datasheets also fit the
>bill.
>
>Danke,

I am wondering, would not a non-switching converter (mains transformer + rectifier followed by maybe a LM317)
give less RFI?

Jan Panteltje wrote:
> Don wrote:

<snip>

>>The TL431 needs to be repurposed into a power supply before my crystal
>>set can accommodate another adornment: an audio amp in the form of a
>>LM386. It turns out the power supply in my "bone yard" chassis supplies
>>only 5 VDC.
>>
>>So a simple SMPS, similar to the flyback converter Win Hill reversed
>>engineered for Figure 9.74 in _Art of the Electronics_, needs to be
>>prototyped:
>>
>><https://archive.org/details/the-art-of-electronics-3rd-ed-2015_202008/page/657/mode/2up>
>>
>>Applications found in both the CSC72XX and UC3843 datasheets also fit the
>>bill.
>
> I am wondering, would not a non-switching converter (mains transformer +
> rectifier followed by maybe a LM317) give less RFI?

Your assessment's absolutely accurate (according to my gut). Regardless,
my tinkering involves more than one goal, and fiddling with SMPS along
the way is acceptable.

And any advice about DIY SMPS transformers from readers is appreciated in
advance.

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

On a sunny day (Fri, 16 Feb 2024 17:04:17 -0000 (UTC)) it happened "Don"
<g@crcomp.net> wrote in <20240216a@crcomp.net>:

>Jan Panteltje wrote:
>> Don wrote:
>
><snip>
>
>>>The TL431 needs to be repurposed into a power supply before my crystal
>>>set can accommodate another adornment: an audio amp in the form of a
>>>LM386. It turns out the power supply in my "bone yard" chassis supplies
>>>only 5 VDC.
>>>
>>>So a simple SMPS, similar to the flyback converter Win Hill reversed
>>>engineered for Figure 9.74 in _Art of the Electronics_, needs to be
>>>prototyped:
>>>
>>><https://archive.org/details/the-art-of-electronics-3rd-ed-2015_202008/page/657/mode/2up>
>>>
>>>Applications found in both the CSC72XX and UC3843 datasheets also fit the
>>>bill.
>>
>> I am wondering, would not a non-switching converter (mains transformer +
>> rectifier followed by maybe a LM317) give less RFI?
>
>Your assessment's absolutely accurate (according to my gut). Regardless,
>my tinkering involves more than one goal, and fiddling with SMPS along
>the way is acceptable.
>
>And any advice about DIY SMPS transformers from readers is appreciated in
>advance.

It is hard to do better than the small wall-warts that you can buy for just a few dollars.
Those use advanced chips with all sorts of protections, are often CE certified
saving you a lot of work, safer too:
https://www.panteltje.nl/pub/floor_warts_IXIMG_0790.JPG

For the switchers I designed I usually use a Microchip PIC as driver chip,
it has 2 build in hardware comparators that you can use for cycle by cycle current limiting
and it has several ADC channels, needs programming though.
As a rule of thumb for transformers: 1V per turn for 15 kHz switching frequency
for small transformers like this one:
https://panteltje.nl/pub/new_transformer_test_setup_img_3153.jpg
But look for inductance, core material, possible air-gap, current, DC bias, frequency, etc etc.
Or grab one from an old defective wall-wart?

Switchers have a lot of negatives, yesterday I repaired a satellite receiver box that had, among several other
regulators, a 5V switcher for the memory and CPU chips and USB memory stick.
it would abort recording on random occasons.
Super small box, the one on the right, rather new:
https://panteltje.nl/pub/sat_box_sizes_IXIMG_0907.JPG
was thinking as it got worse over time, could be a filter cap in one of the switchers.
Opened it and scoped the ripple on the filter caps:
about 1.5V RF spikes on the 5V output cap.
Replaced cap, with one from the junk box, recording works again....
Need to get some low ESR caps, and maybe bias it with a better smaller capacitor.
But even then the thing runs of a 12 V wall-wart... with overload protection.
If you want to get a bit bigger, then get an old PC power supply [transformer],...
Plenty of circuits for that online too.
I often use what I find laying about in the junk box...

Jan Panteltje wrote:
> Don wrote:
>>Jan Panteltje wrote:
>>> Don wrote:
>>
>><snip>
>>
>>>>The TL431 needs to be repurposed into a power supply before my crystal
>>>>set can accommodate another adornment: an audio amp in the form of a
>>>>LM386. It turns out the power supply in my "bone yard" chassis supplies
>>>>only 5 VDC.
>>>>
>>>>So a simple SMPS, similar to the flyback converter Win Hill reversed
>>>>engineered for Figure 9.74 in _Art of the Electronics_, needs to be
>>>>prototyped:
>>>>
>>>><https://archive.org/details/the-art-of-electronics-3rd-ed-2015_202008/page/657/mode/2up>
>>>>
>>>>Applications found in both the CSC72XX and UC3843 datasheets also fit the
>>>>bill.
>>>
>>> I am wondering, would not a non-switching converter (mains transformer +
>>> rectifier followed by maybe a LM317) give less RFI?
>>
>>Your assessment's absolutely accurate (according to my gut). Regardless,
>>my tinkering involves more than one goal, and fiddling with SMPS along
>>the way is acceptable.
>>
>>And any advice about DIY SMPS transformers from readers is appreciated in
>>advance.
>
> It is hard to do better than the small wall-warts that you can buy for just a few dollars.
> Those use advanced chips with all sorts of protections, are often CE certified
> saving you a lot of work, safer too:
> https://www.panteltje.nl/pub/floor_warts_IXIMG_0790.JPG
>
> For the switchers I designed I usually use a Microchip PIC as driver chip,
> it has 2 build in hardware comparators that you can use for cycle by cycle current limiting
> and it has several ADC channels, needs programming though.
> As a rule of thumb for transformers: 1V per turn for 15 kHz switching frequency
> for small transformers like this one:
> https://panteltje.nl/pub/new_transformer_test_setup_img_3153.jpg
> But look for inductance, core material, possible air-gap, current, DC bias, frequency, etc etc.
> Or grab one from an old defective wall-wart?
>
> Switchers have a lot of negatives, yesterday I repaired a satellite receiver box that had, among several other
> regulators, a 5V switcher for the memory and CPU chips and USB memory stick.
> it would abort recording on random occasons.
> Super small box, the one on the right, rather new:
> https://panteltje.nl/pub/sat_box_sizes_IXIMG_0907.JPG
> was thinking as it got worse over time, could be a filter cap in one of the switchers.
> Opened it and scoped the ripple on the filter caps:
> about 1.5V RF spikes on the 5V output cap.
> Replaced cap, with one from the junk box, recording works again....
> Need to get some low ESR caps, and maybe bias it with a better smaller capacitor.
> But even then the thing runs of a 12 V wall-wart... with overload protection.
> If you want to get a bit bigger, then get an old PC power supply [transformer],...
> Plenty of circuits for that online too.
> I often use what I find laying about in the junk box...

My mindset mostly mirrors yours. Here's the story so far:
The chassis came from my bone pile. Its NEMA grounded bulkhead
connector enables an easy connection from a proto-board to ground.
Adding an audio amp along the lines of a LM386 seemed a fitting way
to wrap up the AM receiver before moving on to FM. Unfortunately the
chassis' built-in SMPS only outputs a meager 5 VDC instead of the 12
VDC or, better yet, 24 VDC sought by me.
A quick rummage through my surplus wall warts (over a hundred in
all) unearthed a 12 VDC jewel. The plan was to liberate its board from
its plastic enclosure then swap it into the chassis in place of the
built-in. But the jewel's board didn't cooperate - its footprint was
too small to accomodate the chassis' SMPS mounts.
The jewel seems like simplicity itself. It's scarcely more
complicated than the typical 555 circuit:

<https://crcomp.net/smps/a.png>
<https://crcomp.net/smps/b.png>

Why not assemble a similar circuit from spares on a larger universal board
and also mod it to output 24 VDC?

# # #

Alternatively, all analysis and reverse engineering can be avoided by
using AI to design it:

PI Expert is an automated, graphical user interface (GUI)
driven program that takes power supply specifications and
automatically generates a power conversion solution designed
around the most appropriate Power Integrations’ IC family.
PI Expert provides all necessary information to build and
test a working prototype, including the full schematic and
BOM. PI Expert also provides a complete transformer design
that includes core size, number of turns, appropriate wire
selection and winding construction. Detailed winding
instructions for mechanical assembly are also generated.

<https://pi-expert-suite.software.informer.com/download/#downloading>

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

On a sunny day (Sun, 18 Feb 2024 05:14:16 -0000 (UTC)) it happened "Don"
<g@crcomp.net> wrote in <20240217a@crcomp.net>:

>Jan Panteltje wrote:
>> Don wrote:
>>>Jan Panteltje wrote:
>>>> Don wrote:
>>>
>>><snip>
>>>
>>>>>The TL431 needs to be repurposed into a power supply before my crystal
>>>>>set can accommodate another adornment: an audio amp in the form of a
>>>>>LM386. It turns out the power supply in my "bone yard" chassis supplies
>>>>>only 5 VDC.
>>>>>
>>>>>So a simple SMPS, similar to the flyback converter Win Hill reversed
>>>>>engineered for Figure 9.74 in _Art of the Electronics_, needs to be
>>>>>prototyped:
>>>>>
>>>>><https://archive.org/details/the-art-of-electronics-3rd-ed-2015_202008/page/657/mode/2up>
>>>>>
>>>>>Applications found in both the CSC72XX and UC3843 datasheets also fit the
>>>>>bill.
>>>>
>>>> I am wondering, would not a non-switching converter (mains transformer +
>>>> rectifier followed by maybe a LM317) give less RFI?
>>>
>>>Your assessment's absolutely accurate (according to my gut). Regardless,
>>>my tinkering involves more than one goal, and fiddling with SMPS along
>>>the way is acceptable.
>>>
>>>And any advice about DIY SMPS transformers from readers is appreciated in
>>>advance.
>>
>> It is hard to do better than the small wall-warts that you can buy for just a few dollars.
>> Those use advanced chips with all sorts of protections, are often CE certified
>> saving you a lot of work, safer too:
>> https://www.panteltje.nl/pub/floor_warts_IXIMG_0790.JPG
>>
>> For the switchers I designed I usually use a Microchip PIC as driver chip,
>> it has 2 build in hardware comparators that you can use for cycle by cycle current limiting
>> and it has several ADC channels, needs programming though.
>> As a rule of thumb for transformers: 1V per turn for 15 kHz switching frequency
>> for small transformers like this one:
>> https://panteltje.nl/pub/new_transformer_test_setup_img_3153.jpg
>> But look for inductance, core material, possible air-gap, current, DC bias, frequency, etc etc.
>> Or grab one from an old defective wall-wart?
>>
>> Switchers have a lot of negatives, yesterday I repaired a satellite receiver box that had, among several other
>> regulators, a 5V switcher for the memory and CPU chips and USB memory stick.
>> it would abort recording on random occasons.
>> Super small box, the one on the right, rather new:
>> https://panteltje.nl/pub/sat_box_sizes_IXIMG_0907.JPG
>> was thinking as it got worse over time, could be a filter cap in one of the switchers.
>> Opened it and scoped the ripple on the filter caps:
>> about 1.5V RF spikes on the 5V output cap.
>> Replaced cap, with one from the junk box, recording works again....
>> Need to get some low ESR caps, and maybe bias it with a better smaller capacitor.
>> But even then the thing runs of a 12 V wall-wart... with overload protection.
>> If you want to get a bit bigger, then get an old PC power supply [transformer],...
>> Plenty of circuits for that online too.
>> I often use what I find laying about in the junk box...
>
>My mindset mostly mirrors yours. Here's the story so far:
> The chassis came from my bone pile. Its NEMA grounded bulkhead
>connector enables an easy connection from a proto-board to ground.
> Adding an audio amp along the lines of a LM386 seemed a fitting way
>to wrap up the AM receiver before moving on to FM. Unfortunately the
>chassis' built-in SMPS only outputs a meager 5 VDC instead of the 12
>VDC or, better yet, 24 VDC sought by me.
> A quick rummage through my surplus wall warts (over a hundred in
>all) unearthed a 12 VDC jewel. The plan was to liberate its board from
>its plastic enclosure then swap it into the chassis in place of the
>built-in. But the jewel's board didn't cooperate - its footprint was
>too small to accomodate the chassis' SMPS mounts.
> The jewel seems like simplicity itself. It's scarcely more
>complicated than the typical 555 circuit:
>
> <https://crcomp.net/smps/a.png>
> <https://crcomp.net/smps/b.png>

Nice circuit.
I like they use the TL431, it is a good reference.

>Why not assemble a similar circuit from spares on a larger universal board
>and also mod it to output 24 VDC?

Maybe not enough space for extra windings on the transformer...
but you could try...

># # #
>
>Alternatively, all analysis and reverse engineering can be avoided by
>using AI to design it:
>
> PI Expert is an automated, graphical user interface (GUI)
> driven program that takes power supply specifications and
> automatically generates a power conversion solution designed
> around the most appropriate Power Integrations’ IC family.
> PI Expert provides all necessary information to build and
> test a working prototype, including the full schematic and
> BOM. PI Expert also provides a complete transformer design
> that includes core size, number of turns, appropriate wire
> selection and winding construction. Detailed winding
> instructions for mechanical assembly are also generated.
>
><https://pi-expert-suite.software.informer.com/download/#downloading>

I wonder if as kid I was brought up with that Pi Expert stuff if I would
have chosen an other field.

Sure AI can help, but you need to know the basics.

My first 'learning' came from this book:
https://www.veron.nl/nieuws/zoo-werkt-de-radio/
'that is how radio works'
Aisberg was a very good teacher.
He later also wrote 'that is how television works'
and IIRC same for transistors...
Much later when I worked in TV an other book given to me by somebody
there went into the US NTSC color system.
And then one day I had 20 minutes to repair a converter for the French SECAM
Eurovision system.. Did it, because I had read up on it out of interest.
You need to know basics, and how to use tools.
Had a TV repair shop for several years that grew out to a bigger one...
Fast fault finding requires in dept knowledge.
I am not sure if AI would cope ;-)
I remember fault finding in an ESA ground station, in missile control equipment,
on navy ships... Where not.
But I am just a neural net, a proper trained AI could out-perform me?
work 24/7?
But then one high altitude nuke or heavy solar solar storm and no more
electrickety, we organisms are likely more durable than computahs.
All emerging from what was there? the big-bang and then before that..