Kingslayer voltages/motorboat

[eldanko]

Howdy friends - having a problem with a Kingslayer build. Ironically, the 4th or 5th one I've done.

I was getting some motorboating even on settings with the diodes still in the circuit, so I started poking around a bit. Turns out my 9v1 Zener is hot to the touch. I took voltages and also noticed that I'm not getting anything above 9v on either of the ICs. I should be getting higher off of the TC1044SCPA, right? I swapped the charge pump chip out for another and had the same problem.

Any ideas?

[madbean]

No, you should not get anything higher than 9v. You should have +9v on pim4 of IC1 and -9v on pin11.

[eldanko]

Ah, then in that case IC1 voltages look fine.

Here's IC2 -

1. 9.4
2. 4.7
3. 0
4. -4.5
5. -9.3
6. 4.9
7. 7.3
8. 9.4

Any idea why the zener is getting so hot?

[RobA]

What's your power supply voltage measure when it's unplugged?

[eldanko]

The power supply is sitting at 9.5v unplugged.

Should I be seeing voltage across any of the other diodes?

[RobA]

All the other diodes are just clipping diodes I think so nothing more than the signal that is clipped off and that isn't continuous.

I looked at the schematic/layout for other versions of the Klon circuit and in those the zener is a 12V. So, I assume that it was originally a safety regulator for the charge pump. So, a 9V input wouldn't likely see any drop across the diode. In the Kingslayer, I guess it's been repurposed to add protection for the TLC274. Anyway, your zener is constantly dropping a small amount of voltage across it and it doesn't have any external resistance to limit the current. The link below talks about using a zener as a voltage regulator. If you want to get rid of the heat, there are a couple of things you can do. If you are using an op amp that can take more voltage, then you could move that zener up to whatever the limit is of your charge pump, (10V, 12V, 15V depending on the type). If you are using the TLC274, you could put a current limiting resistor between the 9V on the board and your DC jack. The article I linked shows how to compute the value that you would need.


http://www.electronics-tutorials.ws/diode/diode_7.html