On 3/8/24 8:42 PM, Bill Sloman wrote:
> On 9/03/2024 5:49 am, KevinJ93 wrote:
>> On 3/7/24 8:48 PM, Bill Sloman wrote:
>>> On 8/03/2024 7:13 am, KevinJ93 wrote:
>> ...
>>>>
>>>> Not in 1970. Even after that time they did not possess any advantage
>>>> over DC motor drive with speed stabilization based on back-emf.
>>>
>>> Don't be silly. Back-emf depends on the strenght of the magnetic
>>> field generating the basck-emf, and that is temperature dependent.
>>
>> At about 0.2% per deg the magnetic field strength stability was
>> adequate for the speed accuracy required under the required
>> environmental conditions.
>
> Motors run hotter than their environment

With only 50-100mW being consumed by the motor (10's of mA at 3-6V) the
temperature differential was small.

>>> Synchronous motors rotate at a rate that reflects the stability of
>>> the frequency source that determines the drive frequency, and
>>> reasonably stable frequency source - watch crystals have been around
>>> for ages.
>>
>>>> Even for AC powered units where power was not an issue stepper
>>>> motors were never used. Synchronous motors with synthesized drive
>>>> were occasionally a feature but many/most used back-emf
>>>> stabilization with DC motors.
>>>>
>>>> ICs were available to integrate that circuitry:
>>>>
>>>> eg https://www.precisionmicrodrives.com/ab-026
>>>>
>>>>>> Even implementing the discrete drive electronics would be more
>>>>>> costly than necessary at a time where individual transistors were
>>>>>> a significant cost; Philips' solution used two transistors -
>>>>>> creating a divide by 4 plus driver transistors plus an oscillator
>>>>>> would probably require about ten transistors plus numerous other
>>>>>> components.
>>>>>
>>>>> Which you could could buy in an integrated circuit. Most of mine
>>>>> were in a chunk of PROM.
>>>>
>>>> Not in 1970. Even by the late 70's a bipolar (P)ROM would use up all
>>>> your power budget.
>>>
>>> It didn't - and it wasn't bipolar.
>>
>> MOS EPROMS such as the 1702 were cumbersome to use with multiple
>> supplies required.
>
> It was one-time programmable, not an EPROM.

If it was NMOS it was almost certainly an EPROM in a cheaper package
without the quartz window.

>> The logic to drive them would have been TTL consuming significant
>> amounts of power as well as expensive.
>
> CMOS was around and cheap. I'd first used it around 1975, and the price
> fell by a factor of three as I was developing the 1975 circuit.
>
>> The first EPROMS that were easy to use, such as the 2708 weren't
>> widely available till the late 70's.
>
> The stepper motor circuit that I worked on was developed in 1978.
>
> <snip>
>

On Sat, 9 Mar 2024 14:56:43 -0800, KevinJ93 <kevin_es@whitedigs.com>
wrote:

>On 3/8/24 8:42 PM, Bill Sloman wrote:
>> On 9/03/2024 5:49 am, KevinJ93 wrote:
>>> On 3/7/24 8:48 PM, Bill Sloman wrote:
>>>> On 8/03/2024 7:13 am, KevinJ93 wrote:
>>> ...
>>>>>
>>>>> Not in 1970. Even after that time they did not possess any advantage
>>>>> over DC motor drive with speed stabilization based on back-emf.
>>>>
>>>> Don't be silly. Back-emf depends on the strenght of the magnetic
>>>> field generating the basck-emf, and that is temperature dependent.
>>>
>>> At about 0.2% per deg the magnetic field strength stability was
>>> adequate for the speed accuracy required under the required
>>> environmental conditions.
>>
>> Motors run hotter than their environment
>
>With only 50-100mW being consumed by the motor (10's of mA at 3-6V) the
>temperature differential was small.
>
>>>> Synchronous motors rotate at a rate that reflects the stability of
>>>> the frequency source that determines the drive frequency, and
>>>> reasonably stable frequency source - watch crystals have been around
>>>> for ages.
>>>
>>>>> Even for AC powered units where power was not an issue stepper
>>>>> motors were never used. Synchronous motors with synthesized drive
>>>>> were occasionally a feature but many/most used back-emf
>>>>> stabilization with DC motors.
>>>>>
>>>>> ICs were available to integrate that circuitry:
>>>>>
>>>>> eg https://www.precisionmicrodrives.com/ab-026
>>>>>
>>>>>>> Even implementing the discrete drive electronics would be more
>>>>>>> costly than necessary at a time where individual transistors were
>>>>>>> a significant cost; Philips' solution used two transistors -
>>>>>>> creating a divide by 4 plus driver transistors plus an oscillator
>>>>>>> would probably require about ten transistors plus numerous other
>>>>>>> components.
>>>>>>
>>>>>> Which you could could buy in an integrated circuit. Most of mine
>>>>>> were in a chunk of PROM.
>>>>>
>>>>> Not in 1970. Even by the late 70's a bipolar (P)ROM would use up all
>>>>> your power budget.
>>>>
>>>> It didn't - and it wasn't bipolar.
>>>
>>> MOS EPROMS such as the 1702 were cumbersome to use with multiple
>>> supplies required.
>>
>> It was one-time programmable, not an EPROM.
>
>If it was NMOS it was almost certainly an EPROM in a cheaper package
>without the quartz window.

1702 was a p-mos UV-erase part. It was called an eprom.

On 10/03/2024 9:56 am, KevinJ93 wrote:
> On 3/8/24 8:42 PM, Bill Sloman wrote:
>> On 9/03/2024 5:49 am, KevinJ93 wrote:
>>> On 3/7/24 8:48 PM, Bill Sloman wrote:
>>>> On 8/03/2024 7:13 am, KevinJ93 wrote:
>>> ...
>>>>>
>>>>> Not in 1970. Even after that time they did not possess any
>>>>> advantage over DC motor drive with speed stabilization based on
>>>>> back-emf.
>>>>
>>>> Don't be silly. Back-emf depends on the strenght of the magnetic
>>>> field generating the basck-emf, and that is temperature dependent.
>>>
>>> At about 0.2% per deg the magnetic field strength stability was
>>> adequate for the speed accuracy required under the required
>>> environmental conditions.
>>
>> Motors run hotter than their environment
>
> With only 50-100mW being consumed by the motor (10's of mA at 3-6V) the
> temperature differential was small.

But it was lot bigger inside the motor than you could detect from
outside it.

>>>> Synchronous motors rotate at a rate that reflects the stability of
>>>> the frequency source that determines the drive frequency, and
>>>> reasonably stable frequency source - watch crystals have been around
>>>> for ages.
>>>
>>>>> Even for AC powered units where power was not an issue stepper
>>>>> motors were never used. Synchronous motors with synthesized drive
>>>>> were occasionally a feature but many/most used back-emf
>>>>> stabilization with DC motors.
>>>>>
>>>>> ICs were available to integrate that circuitry:
>>>>>
>>>>> eg https://www.precisionmicrodrives.com/ab-026
>>>>>
>>>>>>> Even implementing the discrete drive electronics would be more
>>>>>>> costly than necessary at a time where individual transistors were
>>>>>>> a significant cost; Philips' solution used two transistors -
>>>>>>> creating a divide by 4 plus driver transistors plus an oscillator
>>>>>>> would probably require about ten transistors plus numerous other
>>>>>>> components.
>>>>>>
>>>>>> Which you could could buy in an integrated circuit. Most of mine
>>>>>> were in a chunk of PROM.
>>>>>
>>>>> Not in 1970. Even by the late 70's a bipolar (P)ROM would use up
>>>>> all your power budget.
>>>>
>>>> It didn't - and it wasn't bipolar.
>>>
>>> MOS EPROMS such as the 1702 were cumbersome to use with multiple
>>> supplies required.
>>
>> It was one-time programmable, not an EPROM.
>
> If it was NMOS it was almost certainly an EPROM in a cheaper package
> without the quartz window.

Perhaps. It was 46 years ago.

<snip>

--
Bill Sloman, Sydney

On Sat, 09 Mar 2024 15:13:20 -0800, John Larkin <jl@997PotHill.com>
wrote:

>On Sat, 9 Mar 2024 14:56:43 -0800, KevinJ93 <kevin_es@whitedigs.com>
>wrote:
>
>>On 3/8/24 8:42 PM, Bill Sloman wrote:
>>> On 9/03/2024 5:49 am, KevinJ93 wrote:
>>>> On 3/7/24 8:48 PM, Bill Sloman wrote:
>>>>> On 8/03/2024 7:13 am, KevinJ93 wrote:
>>>> ...
>>>>>>
>>>>>> Not in 1970. Even after that time they did not possess any advantage
>>>>>> over DC motor drive with speed stabilization based on back-emf.
>>>>>
>>>>> Don't be silly. Back-emf depends on the strenght of the magnetic
>>>>> field generating the basck-emf, and that is temperature dependent.
>>>>
>>>> At about 0.2% per deg the magnetic field strength stability was
>>>> adequate for the speed accuracy required under the required
>>>> environmental conditions.
>>>
>>> Motors run hotter than their environment
>>
>>With only 50-100mW being consumed by the motor (10's of mA at 3-6V) the
>>temperature differential was small.
>>
>>>>> Synchronous motors rotate at a rate that reflects the stability of
>>>>> the frequency source that determines the drive frequency, and
>>>>> reasonably stable frequency source - watch crystals have been around
>>>>> for ages.
>>>>
>>>>>> Even for AC powered units where power was not an issue stepper
>>>>>> motors were never used. Synchronous motors with synthesized drive
>>>>>> were occasionally a feature but many/most used back-emf
>>>>>> stabilization with DC motors.
>>>>>>
>>>>>> ICs were available to integrate that circuitry:
>>>>>>
>>>>>> eg https://www.precisionmicrodrives.com/ab-026
>>>>>>
>>>>>>>> Even implementing the discrete drive electronics would be more
>>>>>>>> costly than necessary at a time where individual transistors were
>>>>>>>> a significant cost; Philips' solution used two transistors -
>>>>>>>> creating a divide by 4 plus driver transistors plus an oscillator
>>>>>>>> would probably require about ten transistors plus numerous other
>>>>>>>> components.
>>>>>>>
>>>>>>> Which you could could buy in an integrated circuit. Most of mine
>>>>>>> were in a chunk of PROM.
>>>>>>
>>>>>> Not in 1970. Even by the late 70's a bipolar (P)ROM would use up all
>>>>>> your power budget.
>>>>>
>>>>> It didn't - and it wasn't bipolar.
>>>>
>>>> MOS EPROMS such as the 1702 were cumbersome to use with multiple
>>>> supplies required.
>>>
>>> It was one-time programmable, not an EPROM.
>>
>>If it was NMOS it was almost certainly an EPROM in a cheaper package
>>without the quartz window.
>
>
>1702 was a p-mos UV-erase part. It was called an eprom.

Are EPROMs obsolete now? I assume they must be or we wouldn't have USB
drives and SD cards etc.

On Sun, 10 Mar 2024 08:59:30 +0000, Cursitor Doom <cd@notformail.com>
wrote:

>On Sat, 09 Mar 2024 15:13:20 -0800, John Larkin <jl@997PotHill.com>
>wrote:
>
>>On Sat, 9 Mar 2024 14:56:43 -0800, KevinJ93 <kevin_es@whitedigs.com>
>>wrote:
>>
>>>On 3/8/24 8:42 PM, Bill Sloman wrote:
>>>> On 9/03/2024 5:49 am, KevinJ93 wrote:
>>>>> On 3/7/24 8:48 PM, Bill Sloman wrote:
>>>>>> On 8/03/2024 7:13 am, KevinJ93 wrote:
>>>>> ...
>>>>>>>
>>>>>>> Not in 1970. Even after that time they did not possess any advantage
>>>>>>> over DC motor drive with speed stabilization based on back-emf.
>>>>>>
>>>>>> Don't be silly. Back-emf depends on the strenght of the magnetic
>>>>>> field generating the basck-emf, and that is temperature dependent.
>>>>>
>>>>> At about 0.2% per deg the magnetic field strength stability was
>>>>> adequate for the speed accuracy required under the required
>>>>> environmental conditions.
>>>>
>>>> Motors run hotter than their environment
>>>
>>>With only 50-100mW being consumed by the motor (10's of mA at 3-6V) the
>>>temperature differential was small.
>>>
>>>>>> Synchronous motors rotate at a rate that reflects the stability of
>>>>>> the frequency source that determines the drive frequency, and
>>>>>> reasonably stable frequency source - watch crystals have been around
>>>>>> for ages.
>>>>>
>>>>>>> Even for AC powered units where power was not an issue stepper
>>>>>>> motors were never used. Synchronous motors with synthesized drive
>>>>>>> were occasionally a feature but many/most used back-emf
>>>>>>> stabilization with DC motors.
>>>>>>>
>>>>>>> ICs were available to integrate that circuitry:
>>>>>>>
>>>>>>> eg https://www.precisionmicrodrives.com/ab-026
>>>>>>>
>>>>>>>>> Even implementing the discrete drive electronics would be more
>>>>>>>>> costly than necessary at a time where individual transistors were
>>>>>>>>> a significant cost; Philips' solution used two transistors -
>>>>>>>>> creating a divide by 4 plus driver transistors plus an oscillator
>>>>>>>>> would probably require about ten transistors plus numerous other
>>>>>>>>> components.
>>>>>>>>
>>>>>>>> Which you could could buy in an integrated circuit. Most of mine
>>>>>>>> were in a chunk of PROM.
>>>>>>>
>>>>>>> Not in 1970. Even by the late 70's a bipolar (P)ROM would use up all
>>>>>>> your power budget.
>>>>>>
>>>>>> It didn't - and it wasn't bipolar.
>>>>>
>>>>> MOS EPROMS such as the 1702 were cumbersome to use with multiple
>>>>> supplies required.
>>>>
>>>> It was one-time programmable, not an EPROM.
>>>
>>>If it was NMOS it was almost certainly an EPROM in a cheaper package
>>>without the quartz window.
>>
>>
>>1702 was a p-mos UV-erase part. It was called an eprom.
>
>Are EPROMs obsolete now? I assume they must be or we wouldn't have USB
>drives and SD cards etc.

Some of our older VME modules use DIP eproms in sockets, and 68332
CPUs. We seem to be able to get both. We don't buy the UV window parts
any more.

On 10/03/2024 7:59 pm, Cursitor Doom wrote:
> On Sat, 09 Mar 2024 15:13:20 -0800, John Larkin <jl@997PotHill.com>
> wrote:
>
>> On Sat, 9 Mar 2024 14:56:43 -0800, KevinJ93 <kevin_es@whitedigs.com>
>> wrote:
>>
>>> On 3/8/24 8:42 PM, Bill Sloman wrote:
>>>> On 9/03/2024 5:49 am, KevinJ93 wrote:
>>>>> On 3/7/24 8:48 PM, Bill Sloman wrote:
>>>>>> On 8/03/2024 7:13 am, KevinJ93 wrote:

<snip>

>> 1702 was a p-mos UV-erase part. It was called an eprom.
>
> Are EPROMs obsolete now? I assume they must be or we wouldn't have USB
> drives and SD cards etc.

EPROMs are obsolete, but they were replaced by electrically erasable PROM.

USB cards and SD cards do the same job, but they cost more and take up
more space on the board - if you don't need much programmable memory an
EEPROM can be big enough.

https://au.element14.com/w/c/semiconductors-ics/memory/eeprom/prl/results?ost=eeprom&sort=P_PRICE

--
Bill Sloman, Sydney

On 3/9/24 3:13 PM, John Larkin wrote:
> On Sat, 9 Mar 2024 14:56:43 -0800, KevinJ93 <kevin_es@whitedigs.com>
> wrote:
>
>> On 3/8/24 8:42 PM, Bill Sloman wrote:
....
>>>>>
>>>>> It didn't - and it wasn't bipolar.
>>>>
>>>> MOS EPROMS such as the 1702 were cumbersome to use with multiple
>>>> supplies required.
>>>
>>> It was one-time programmable, not an EPROM.
>>
>> If it was NMOS it was almost certainly an EPROM in a cheaper package
>> without the quartz window.
>
>
> 1702 was a p-mos UV-erase part. It was called an eprom.
>

I know, that's why I said that the 2708 series were the first convenient
to use ones with a single power supply.

Although an EPROM, some equivalent parts were available in a cheaper
package without a window - they were one-time programmable.

kw