Friedemann Wachsmuth

See, he wanted to build a "video camera", not a motion picture camera. This was a fun project of a maker, not an attempt to build a pro camera, nor a business.

Very true — I in fact have a background in hardware production and know what it all costs. Tyler's 15+5=30 math just left a vague gap. (Margins are important too, if a company wants to survive...)

Where do the remaining 10k came from? Sales margin? 🤔

Absolutely brilliant in all regards, @kanery hiddelstone - @Henry kidman. You did it. I admire how you coped with all the "forget it, it's impossible" attitude. Yeah, registration isn't perfect — but that is so irrelevant for the overall success and story. And I find both amazing!

You got mail. I'd so be in!

I have no words for how much I love this from all angles.

Amazing outcome!! Congratulations!

EDIT: After looking closer at the schematics, I think the tacho is actually sending 80 pulses per revolution — the 8493 divides that down to 10, matching the 240 Hz from the decimal divider behind the crystal.

Thanks, Thomas. So my date-guess was right (Schematics from 1972), and it is indeed dividing by 800, so the tacho seems to send 8 pulses per revolution. A very neat and pragmatic control circuit design indeed.

Ah, I see. I must have mixed you up then with someone else who insisted against using uCs an/or DDS for frequency generation a while ago. Sorry. 🙂

For anybody interested, below is my C code (free) that configures the "Timer 1" on a AtMega328p (aka Arduino) running on at 16 MHz crystal to rather precise 9, 16 2/3, 18, 24 or 25 Hz pulse machines. The results (e.g. 24.000024 Hz) are higher precision than a normal crystal itself — if required (and you are using a temperature compensated crystal or whatever) , the small diff from actual 24 Hz can rather easily be corrected in software. bool setupTimer1forFps(byte sollFpsState) { // start with a new sync point, no need to catch up differences from before. timerFrames = 0; projectorFrames = 0; timerDivider = 0; if (sollFpsState >= 1 && sollFpsState <= 5) { Serial.print(F("New Timer FPS State: ")); Serial.println(sollFpsState); noInterrupts(); // Clear registers TCCR1A = 0; TCCR1B = 0; TCNT1 = 0; // CTC TCCR1B |= (1 << WGM12); switch (sollFpsState) { case FPS_9: OCR1A = 10100; // 198.000198000198 Hz (16000000/((10100+1)*8)), // divided by 22 is 9,000009.. Hz // TCCR1B |= (1 << CS11); // Prescaler 8 timerFactor = 22; break; case FPS_16_2_3: OCR1A = 14999; // 16 2/3 Hz (16000000/((14999+1)*64)) TCCR1B |= (1 << CS11) | (1 << CS10); // Prescaler 64 timerFactor = 1; break; case FPS_18: OCR1A = 10100; // 198.000198000198 Hz (16000000/((10100+1)*8)), // divided by 11 is 18.000018.. Hz // or 18 2/111,111 // or 2,000,000/111,111 // TCCR1B |= (1 << CS11); // Prescaler 8 timerFactor = 11; break; case FPS_24: OCR1A = 60605; // 264.000264000264 Hz (16000000/((60605+1)*1)), // divided by 11 is 24.000024.. Hz // or 24 8/333,333 // or 8,000,000 / 333,333 // TCCR1B |= (1 << CS10); // Prescaler 1 timerFactor = 11; break; case FPS_25: OCR1A = 624; // 25 Hz (16000000/((624+1)*1024)) TCCR1B |= (1 << CS12) | (1 << CS10); // Prescaler 1024 timerFactor = 1; break; default: break; } // Output Compare Match A Interrupt Enable TIMSK1 |= (1 << OCIE1A); interrupts(); } else { // invalid fps requested Serial.println(F("Invalid FPS request")); return false; } }

The date code on these chips indicates that they are probably from 1973/74. Manufacturer is National Semiconductor — the reason that you didn't find datasheets easily is that these were "military grade". NS names the 74xx series chip as 84xx if they e.g. allowed higher temperature grades. So, basically they are 7490 and 7493. Both are monolithic counters. They contain four master-slave flip-flops and additional gating to provide a divide-by-two counter (total counts up tp 10) and a three-stage binary counter (counts up to 16). As far as the PCB traces suggest, the 7490 were configured as counting to 10, so resulting in dividing the 24 kHz down to 240 Hz — as Aapo suggested. The motor probably didn't provide 10 pulses per rotation though but a power of 2 (so 2, 4, 8 or 16) — hance the xx93. What Aapo didn't mention though is that just having two frequencies is not controlling the motor speed yet. comparing the pulse count and turning it into a (non-oscillating) control voltage for the motor is the other half of the challenge. They have achieved this without any OpAmp! I am rather amused by that ancient type of crystal coming in a glass tube — especially since it seems to be bedded on some foam and mounted with a... rubberband? 🙂 This isn't quite right. You cannot only divide by powers of 2 (like 8192 or 1024) with discrete counters. With e.g. a 4017 you can also divide by 3, 4, 5, 6, 7, 8, 9 or 10 — just the duty cycle changes unless you fix it with further flip-flops. So, a 6 MHz crystal (common for USB interfaces) can provide 24 and 25 fps references, a 18 MHz crystal (typical SD-TV pixel clock) can provide 18, 24 or 25 fps references with such "old school dividers". I am glad that you finally switched to software, Aapo — are you using the 328p timer configs I shared with you back in the day? 🙂

https://www.filmomat.eu/shop/manual-816mm-processing-system

I can't prove it but think you are on a wrong track here. ? Can't wait for your tests though! I'll shoot my two rolls next Sunday, haven't decided yet how I'll process them. I was considering ECN-2 and the getting a proper print, so that I can't really bend its curves.

They always say that, even when I speak to other Germans ? Guess I should make an English version of that video, too. Too bad that currently no new Adox cartridges are being made, the tools are all still there though.