I'm looking at building a PNP Ge fuzz face with a max1044 chip to convert the voltage.
I'm going by RG's diagram here:
http://www.geofex.com/circuits/voltpmp2.gif (http://www.geofex.com/circuits/voltpmp2.gif)
I'm just a bit confused as to how it connects to a PNP circuit.
presumably the -9v (pin 5) goes to the -9v of the FF circuit.
but what connects to the +9v of the FF and what is ground? this is where I get confuddled.
if +9v from the chip (pin 8) connects to +9v ground of the FF, what is pin 3 grounded to?
I feel I'm missing something really obvious. :icon_redface:
ok, found this which helps a bit:
http://www.tonepad.com/getFile.asp?id=118 (http://www.tonepad.com/getFile.asp?id=118)
but I'm still confused about the difference between ground and +9v from the chip.
is say, the ground that the FF's Q1 emitter connected to, the same as the ground connected to pin3 of the chip?
so if I understand the tonepad diagram, the +9v of the chip is ignored, and the -9v powers the effect?
From reading the description of Tonepads bipolar power supply, you are correct that the -9volts is used for power and the +9volts is ignored. The ground is the same point on the power supply and the project.
thanks, yeah that what I get from it too.
I have it like that on the breadboard right now but its not happening for me.
I get -4.7v at pin5, which I've connected to the -9v rail of the effect, but I'm getting 0v at that rail.
all that's connected to that rail is the 490R and 33k of the fuzz face.
Yep, CC is right.
The whole point is to take an existing +9V, which can be used for other pedals, and ground, which goes to other pedals also, and make from these a -9V which can power a Fuzz Face or other PNP positive ground pedal without the power/ground interaction you'd otherwise get.
The whole thing will make more sense if you draw in some other blobs which represent other pedals, and take +9V and ground over to them. Then ground and the new -9V go to your fuzz face. Everybody gets to use the same ground and play nice together.
Quote from: skrunk on February 19, 2011, 11:44:20 AM
I get -4.7v at pin5, which I've connected to the -9v rail of the effect, but I'm getting 0v at that rail.
all that's connected to that rail is the 490R and 33k of the fuzz face.
You have a connection or hookup bug.
heh the chip wasn't sitting in the breadboard fully :icon_redface:
works a treat now, thanks guys!
this is really useful.
Quote from: skrunk on February 19, 2011, 12:24:00 PM
heh the chip wasn't sitting in the breadboard fully :icon_redface:
My favorite trick to play on myself is to socket ICs in a board, then do my debugging from the bottom/trace side and not notice I didn't put ICs in the sockets.
:icon_lol: