PNP / NPN - polarity reverse...

[LucifersTrip]

A beginner question...

Regarding the original fuzz face made with PNP transistors:
http://fuzzcentral.ssguitar.com/fuzzface/fuzzfacepnpschematic.gif

I noticed right away that the polarity was reversed on the battery & caps on an NPN version:
http://www.muzique.com/lab/yaff.gif

...which makes sense to me as a novice.

Then, there's this NPN version, where the polarity of the battery & C3 is reversed from the original PNP version,
but C1 remains unchanged:
http://www.beavisaudio.com/Projects/fuzzModular/FuzzFaceSchematic.gif

can someone please explain..

Update: I think I see that the switch configuration of Yaff version needs the reversal, but the beavis version has + input so it makes sense.

[Bad Chizzle]

I've found that sometimes in a schematic a generic electrolytic symbol is placed assuming the reader will know how to orient said cap.  In this schematic the first cap should be negative toward jack, while c3 should be negative to ground. Hope I'm correct on this and I have helped some. As you start reading more schematics you will see that it's done in different ways now and then and you'll get used to them.

[jasperoosthoek]

Indeed Bad Chizzle is correct, C1 has to be reversed. The reasoning is that the input signal will be at the DC level of the ground and the base of the resistor will be at a slightly higher voltage, say 0.3 volts (about 0.6 to 0.7 volts for silicon). I would add a very high resistor (for instance 4.7 megaohms) between the input and the ground. That will keep the cap charged properly when the effect is turned off. Otherwise when you turn it on can hear a loud pop. Some designs already incorporate this as the only effect it has is removing the pop.

It is a good thing that you start comparing schematics and that you start to understand these things. The learning curve is steep but rewarding.

[petemoore]

  Make the - lead mark on the cap be negative in relation to the positive lead, reverse polarity to destroy capacitor.
  Make it not matter using a bipolar = nonpolarized capacitor.
  Make 1 bipolar/nonpolar capacitor with 2 caps:
  +cap--cap+
---------------------------------------------
   +-
   CC
   AA
   PP
   +-
 
 

[LucifersTrip]

thanx much for all the info...I will reverse all polarities when switching from PNP tp NPN

are there exceptions?