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Troubleshooting a homemade AY-3-8500 pong board


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So I thought it might be a fun quarantine project to build a pong machine using one of my spare AY-3-8500 chips, but I've run into some snags. I decided to wire up the bare minimum of parts just to see if I could get a picture on the screen, but so far, bupkis. I think my 2MHZ clock might be part of the problem, I just don't think I can use three inductors in series to add up to 90uH. Or maybe something else needs to be wired up before a picture will generate? I dunno, I'm just spitballing at this point. I've attached a picture showing my (not so) handiwork.


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  • 4 months later...
39 minutes ago, 5-11under said:

I'm not sure what frequency range the output, to the TV, can tolerate. I'd order the crystal, but in the meantime, you could try some other capacitor/inductor values, to try to zone in on the correct frequency.

I'd definitely start with replacing the transistor oscillator circuit with an actual crystal or oscillator. I'm not familiar with the pong chip above, but the usual +/-20% tolerance on discrete components doesn't work well with circuits that need a stable clock. EDIT: looking at your picture as well, it's usually not best practice to have your clock circuit so far away from your clocked device. Your clock signal may not be stable enough by the time it gets to the chip.



On 7/2/2020 at 9:29 PM, Nateo said:

 I just don't think I can use three inductors in series to add up to 90uH.

You can in fact use three inductors in series to get 90uH. In series inductors work like resistors; the inductance adds together.

Edited by BDW
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