I'm building a circuit driven by an Arduino UNO that controls a AY-3-8910 programmable sound generator.

The AY has three pins labeled Channel A, B and C. Each output is an independent sound channel.

I am piping the audio through an LM386 which then drives a small PC speaker.

When I run a single channel, it sounds pretty good. But each time I mix another channel, things start getting really distorted.

I've built this on a breadboard in the past and it sounded great so I don't know what I'm doing wrong this time.

Below is a crude schematic of my circuit. I didn't draw the LM386 because it's the same with or without it and I never used it before.

Any ideas how I can cleanly mix these signals? I don't remember doing anything in the past other than literally connecting all three channels together.

I can provide more schematics and/or videos or pictures too. This is driving me nuts. So I'm hoping someone out there has worked with this sound generator in the past that can provide some insight.

Thanks.

schematic

simulate this circuit – Schematic created using CircuitLab

  • 1
    The LM386 has differential inputs, how are you hooking it up to the single ended AY-3-8912? Also, the LM386 has some intrinsic gain, you are probably exceeding its rails (the AY-3-8912 outputs a 1V PP square on each channel...) – Zuofu May 20 '15 at 0:24
up vote 4 down vote accepted

Typical circuit diagram from the manual shows a 1K resistor to ground and capacitive coupling. Both are necessary. The 10K may also be required.

enter image description here

  • 1
    I'm an idiot. I totally missed that even after scanning the AY datasheet. Ugh. Rookie mistake. Now it sounds great! Thanks. – cbmeeks May 20 '15 at 0:45

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