Rebuilding my old analog console

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Originally Posted by Kevint

Ok. I haven't tried any of the recommended changes yet. At the moment I'm only running 1 scanner set, so I breadboarded 2 more scan amps and last night I wanted to play around with chopping the beam. I put a blade on a scanner and sent a signal to it from an oscillator and when I turned up the gain, there was major crosstalk noise on my laser image (it really distorted the image). The only thing I could figure out last night was to hook the scanner ground wire directly to the power supply ground and that got rid of 95% of the crosstalk but not all of it. At that point I was able to test the chopper and got some really cool stuff. What I don't understand is that I do not see crosstalk on my xy scan pair. It only showed up when I added a 3rd scanner. The circuits are identical.

Any recommendations on how to get rid of crosstalk?

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More diagrammatic insight would be helpful but in short, each scan driver ground, main signal generation grounds (XY and chopper signal) and the power supply grounds should tie together at one and only one point, usually at the PSU ground. Signal generation ICs should have .1uF decoupling capacitors closely connected to their power pins to ground. Good luck. ;-)

Thank you. Very helpful. I'll add 0.1uf caps to the op amps and run all the scanner wires as mentioned. I'm assuming stand orange disc capacitors are ok. If now what would be a better choice?

I'll be posting the scan amp schematic shortly.

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Originally Posted by Kevint

Thank you. Very helpful. I'll add 0.1uf caps to the op amps and run all the scanner wires as mentioned. I'm assuming stand orange disc capacitors are ok. If now what would be a better choice?

I'll be posting the scan amp schematic shortly.

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Ceramic caps would be fine, just make sure their voltage ratings are about double the voltages on the op amp power pins.

Those classic controllers were all analog if I'm not mistaken..I'd sell em but rather trade im sure ever part u would need is there and exsteamly mint used less than a few months ..I'll put up a picture

Attachment 60939


Maybe could help

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Originally Posted by Werewoofer808

Attachment 60939


Maybe could help

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Thank you for the photos

Added caps and did some wire management and I'm about 95% there. Thank you all.

Here is the schematic for the scanner amp.

I think this has what Laserist recommended

See attached

That's a start. Instead of having discreet x/y summing amps for each channel (scan set) just use one (with a master gain/symmetry) and put a x/y gain on each output channel. That way you can include variable z axis rotation, audio mod, spirals etc. without a circuit per channel. Well you're still going to want a circuit per n-1 channels for fixed rotation. Nothing wrong with a bunch of discreet circuits per channel, except it's expen$ive and kind of hard to perform when some one in the studio is constantly changing up how the image path is configured... I assume the scanamps and joystick stuff are just placeholders. A master joystick gain, joystick enables and various fixed rotation z axis joystick rotations per channel are performance assets.

This might help if you go to more complex waveforms, such as square or triangle:
It can be adapted to what you have.

Steve

https://photonlexicon.com/forums/att...1&d=1609873841