oscillators in camera circuits

AgX · Feb 24, 2016

The Canon AE-1 is the first camera to have an oscillator, it is necessarily added to its digital processor.
A first for camera control.

The Contax 139 Quartz introduced 2 years later is stated by the manufacturer to be the first to have a quartz oscillator.

Now for me the question arises, what kind of oscillator the AE-1 got?

Its frequency is given down to one Hz, in this case I can't think of anything else than a quartz oscillator.
Yes I know of a lot of other oscillators, but am not sure they would fit in size, accuracy or time of introduction.
Am I wrong?

polyglot · Feb 24, 2016

Quartz is the most likely, but stating the frequency to within 1Hz does not mean that it is that accurate. A good modern crystal is accurate to maybe 20ppm, and that's much better than when the AE1 was made.

ic-racer · Feb 24, 2016

I have seen astable or monostable multivibrator circuits constructed with logic gates in photography gear without quartz.

AgX · Feb 24, 2016

I already was hinted at that the frequency I referred to is likely just a nominal one, and thus not mean at all that the oscillator actually is that accurate.
And thus the oscillator may be based on transitors forming a flop.

DWThomas · Feb 24, 2016

I vaguely recall there were some oscillators along the way that were described as "ceramic resonators" as opposed to the more traditional quartz plates. My recollection is they were not at the few parts per million accuracy level, but adequate for many consumer gadgets.

AgX · Feb 24, 2016

Yes, ceramic filters were the consumer graded ones in the world of radios for instance.

sfaber17 · Feb 24, 2016

Seems like flash circuits had oscillators to make the high voltage (but would not use crystal), earlier than that, unless cameras with built in flashes were newer than the Cannon.

Luckless · Feb 24, 2016

Also don't forget that marketing departments will frequently say whatever they think they can get away with to sell more products till someone calls them out on it. So a company promotional document saying "We're the first to ever do this!" is easily read as "We're the first to ever CLAIM this in documentation and make a deal out of it..."

AgX · Feb 24, 2016

That statement was done in a german ad and West-Germany even back then was quite strict on this matter. It even was prohibited to Name a competing product/manufacturer in a comparison.

DWThomas · Feb 24, 2016

sfaber17 said:
Seems like flash circuits had oscillators to make the high voltage (but would not use crystal), earlier than that, unless cameras with built in flashes were newer than the Cannon.

Yes, electronic flash circuits typically use a DC-to-DC converter that used a transformer and transistors to up the battery voltage. Many are relatively 'brute force'. The oscillation frequency was at least partly a function of the magnetic properties of the transformer, and nowhere near a precise frequency. In fact on many you can hear the frequency change as the load drops as the storage capacitor charge builds.

AgX · Feb 24, 2016

sfaber17 said:
Seems like flash circuits had oscillators to make the high voltage (but would not use crystal), earlier than that, unless cameras with built in flashes were newer than the Cannon.

They still have. To yield the necessary "high"-voltage the DC from the typical battery pack had to be transformed, and that is only possible by converting into AC and after transforming-up rectifying again to charge the capacitors. The first oscilators in flash units were even mechanical.

But this is so obvious that I considered it unnecessary to hint at the case of cameras with built-in electronic flash unit.

DWThomas · Feb 24, 2016

And back in the 1950s, some shoulder bag sized units carried batteries up in the 200 volt range that were once common for powering old tube ('valve') radios. Fiddling with them offered some opportunity for excitement.

Prof_Pixel · Feb 24, 2016

From http://diagramas.diagramasde.com/camaras/CANON AE-1 PROGRAM REPAIR MANUAL.pdf page 44: 32 KHz clock signal (tolerance 30,117 to 34,134 Hz)

Page 15 discusses the clock signal and where it comes from.

AgX · Feb 24, 2016

I got the same manual, looked at it before, but did not see that tolerance stated. Thank you for that hint.
This would be a proof that the clock frequencies stated by Canon are just nominal figures.

The clock signal for the Contax is shown in that ad as zig-zag oscilloscope line (@32.768KHz), whereas the Canon signal is in the manual shown and described as of square character.
I see that as another hint at the different characters of the oscillators.

oscillators in camera circuits

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