Inverter question

[perfectlyfineusername]

Hi, I was thinking of putting together this fuzz face with an inverter ( https://shop.pedalparts.co.uk/product/fuzzface ). The pdf says the capacitors are orientated for pnp which I'm building. my question is if I use the inverter, do I need to swap these around? I assume I don't but I'd just thought I'd ask and double check in case I'm wrong. Especially since I'm thinking of selling it to someone local to make a little bit of money, it wouldn't be a good look if it blew up on them lol

[Matthew Sanford]

Looking at their site, the inverter is for the power to create the positive ground the PNP wants for the FF. The cap orientation (I think) is more about if you use an NPN or PNP than if you have the inverter. THat is there to apparently change the negative ground power supply we all use to a positive ground within the circuit, allowing it work friendly like daisy chained with other pedals.

Smart people pretty please correct me if I'm wrong here, don't want to lead anyone astray...

[ElectricDruid]

+1 agree with Matthew. The inverter is only there to let you use a standard negative ground power supply with a positive-ground PNP circuit like the fuzz face. The caps don't change around.

[perfectlyfineusername]

Looking at their site, the inverter is for the power to create the positive ground the PNP wants for the FF. The cap orientation (I think) is more about if you use an NPN or PNP than if you have the inverter. THat is there to apparently change the negative ground power supply we all use to a positive ground within the circuit, allowing it work friendly like daisy chained with other pedals.

Smart people pretty please correct me if I'm wrong here, don't want to lead anyone astray...

So basically I don't need to bother swapping the capacitors around when using the inverter?

[Mark Hammer]

Correct.  The charge-pump/inverter allows the standard +9V power supply to behave as if it was the 9V battery with positive ground that would have been powering the circuit back in the early '70s.  So nothing about the original circuit has to change, including the orientation of transistors or caps.

[Phend]

Where do I find a good inverter circuit / schematic ?
I have looked at some refs and it is said that some ic's are sensitive and apt to burn out at voltages around 10v.

[R.G.]

You have to look at the data sheet for the charge pump IC you will use. The original icl7660 had an absolute maximum input voltage of 10.00000000V Anything higher and it died. There are several ICs available today that have max input voltages of 12 to 15V. The LT1054 was the go-to a decade ago, but there may be others today. The number 7660S comes to mind, but check the data sheet. The schematics will all be very similar, only varying in capacitor value and whether pin 8 can be wired as a frequency booster enable.

The schematic is not the circuit, in a poor paraphrase of "the map is not the country". It tells you connections assuming ideal zero-resistance wires. Real wires are not zero resistance. This matters because the charge pump IC is going to pull in big-ish pulses of current from its voltage supply and send equal-and-opposite pulses back out through its ground wire. The ground wire resistance can make for a very whine-prone supply if you don't hook up the grounds to the right places.

[Phend]

I presume this wiring diagram would work to invert 9v using the LT1054 (15v max input).
Maybe change the 47uF cap to 100uF and add 2uF to pin 8.
On the diagram I see pin 1 and 8 are connected, however on the LT1054 data diagram they are not ?
Also on that wiring diagram I assume the sleeves of the in and out jacks are simply connected to the GND strip.
Thanks for any comments

[mzy12]

Add a 100nF cap between the ground pin and 9v in and another one between -9v out and ground. Should also help with noise.