Download Helper Application to Calculate Fuzz Face Bias w/leakage

[mac]

I upgraded the program to include the effect of leakage current. Use it to estimate voltages and currents in a Fuzz Face circuit. This is a preview version. Final one will also compute voltage divider and big muff stages w/leakage.

The equations are very sensible to small variations, mainly on Q1's properties. Do not expect precise predictions, just estimates values, unless you can measure with great accuracy.

http://www.geocities.com/guitarfxs/exes/FuzzFaceBias.zip

MacOSX and Winboxes are zipped in the above file.

bugs: change the decimal separator if you get unexpected results. "," <--> "." The app does not check if you type numbers or letters.

Note: R1 is the std 33k, R2 the sum of the 8.2k and the 470R, R3 the 1k fuzz pot, R4 the 100k feedback resistor, Hfe the gain, Vbe the voltage drop across the base and the emitter, iL the leakage current, Vcc the battery voltage.

mac

[cd]

Very interesting program, thanks for posting it.

Question: is there any way to REVERSE the calculations, i.e. plug in measured voltages and resistances and have it come up with hFE?

Also which schematic are you referring to with R1/R3/R2 etc.?

[mac]

1. r1 is the usual 33k; r2 the sum of the std 8.2k and the 470; r3 is the 1k fuzz pot; r4 the 100k feedbak resistor.
Vbe is the voltage drop across base and emitter, 0.1v - 0.3v for Ge, 0.5v - 0.7v for Si.
2. Yes, eqs can be reversed.



mac

[mac]

I compiled the win version using realbasic for macosx. I did not check how it behaves on a pc. Please let me know.


mac

[cd]

I compiled the win version using realbasic for macosx. I did not check how it behaves on a pc. Please let me know.

OK I finally got my copy of VPC working, seems to work identically to the OSX version.

Will you be posting up a different verison where the voltages can be plugged in, like a reverse version? 

[mac]

OK I finally got my copy of VPC working, seems to work identically to the OSX version.
Will you be posting up a different verison where the voltages can be plugged in, like a reverse version?

No, I dont think so, at least in the near future. I still have to include the voltage divider and BMP section but I can not find some free time to do it. 
I can send you the eqs if you want. Instead of fixing R2, Q2's collector resistor, and solve for Vc2, you have to fix Vc2 and solve for R2. That is what the prior version of the app does.


mac