Could ICL7660SCPAZ be used for supplying -9v out of 9v?

[karolisd]

Hi, I've made a few germanium fuzzes and would like to make them able to share power supply with other pedals, just like in this article: http://www.geofex.com/circuits/+9_to_-9.htm . Could ICL7660SCPAZ be used for this?

[IvIark]

Yes, like this:

http://tagboardeffects.blogspot.com/2012/05/negative-voltage-inverter.html

This is a layout doing the same thing with a MkII:

http://tagboardeffects.blogspot.com/2012/03/tone-bender-mkii-pnp-with-negative.html

I've done it successfully with a few classic PNP effects now with no issues, and it's very nice to be able to use the more consistent PNP transistors rather than take a gamble on NPN (which in my previous experiences have been disappointing).

[karolisd]

Thanks! I bought some gt404, which are NPN. However, most of them have leakages above 500uA, so now I'm using pnp gt313a instead.

[IvIark]

That's exactly what I found with the GT404.  Out of 50 only 8 had less than 500uA leakage, whereas the GT402 there was only 2 bad ones out of 50.  The only consistently good NPN germaniums I've used are the MP38A and all 50 were very low leakage, but gain only ranged from around 50 to 90.

[Toney]

 If you have a few common transistors and caps lying around you can build an inverter.
Look a few message s down...

   http://www.diystompboxes.com/smfforum/index.php?topic=97425.0