Disable charge pump on Knight of tone

falcon75 · Post by **falcon75** » 16 Oct 2022, 21:21

Hello Pedal Builders,

I have build a Knight of Tone from PCB Guitar Mania which plays very well. Now the building docs https://pcbguitarmania.com/wp-content/u ... g-Docs.pdf recommend to try it without the Charge Pump if using it with a lot of overdrive.
The doc says there is a graphic which shows howto bypass the charge pump.
Unfortunately I‘m not able to find the required information or graphic.

Looking at the schematic, I’m wondering if I simply need to remove IC3 and that‘s it. Can somebody confirm that?

If I want to have it switchable how can I do this?

Thanks for your help and feedback.

mauman · Post by **mauman** » 17 Oct 2022, 00:57

Remove IC3 (charge pump). Remove D14 and D15 and replace them with straps, or leave them in and strap around them. The 9V input will then become your V+. You won't need C11, C12 or C13 but it won't hurt to leave them in if they're already installed.

The best way to make it switchable is to move the DC protection and charge pump circuit to a separate vero board, then run the 18V vero output and 9V to lugs 1 and 3 of a SPDT, with lug 2 of the SPDT to the +9V input of the PCB. If you're interested let me know and I can post a diagram.

Manfred · Post by **Manfred** » 17 Oct 2022, 01:15

If you disconnect pin 4 of the LT1044 from ground it should no longer be activated, so switching would be possible, try it.
A simple possibility would be to use a 5V power supply.

falcon75 · Post by **falcon75** » 17 Oct 2022, 18:23

Thanks @mauman @Manfred,

I will give it a try.