[sdiy] Dual transistor amp in Synthacon

[Aaron Lanterman]

http://www.cgs.synth.net/modules/cgs35_syntha_vcf.html

Later version...

There's a 2N2222 NPN and a 2N2907 PNP.

It looks like the input goes to the base of the 2N2222, and the output is 
taken from the collector of the 2N2907. The emitter of the 2N2907 is tied 
to a positive coltage supply.

The emitter of the 2N2222 is tied through 2k2 to ground. Let's call that 
2k2 resistor RG.

Then, there's a 1K resistor and 1K pot in series; let's call that 
combination RF. It feedsback from the collector of the @n2907 to the 
emitter of the 2N2222.

What is the gain of this configuration as a function of RG and RF?

That's probably obvious to those zen in transistors, which I often admit 
to my class that I am not. Rather than do a detailed analysis on my own, 
since I should be entering grades and not puttering about with a 
transistor circuit, I pulled out my trusty Horowitz and Hill, but can't 
find anything exactly like that... The closest I find is a reference to a 
"Sziklai connection" aka "complementary Darlington," but the description 
doesn't have the resisotrs. Since I can't find it, I turn to the gurus...

- Aaron

-----------------------------------------------------------------------------

Dr. Aaron Lanterman, Asst. Prof.
and Demetrius T. Paris Junior Prof.    Voice:  404-385-2548
School of Electrical and Comp. Eng.    Fax:    404-894-8363
Georgia Institute of Technology        E-mail: lanterma at ece.gatech.edu
Mail Code 0250                         Web:    users.ece.gatech.edu/~lanterma
Atlanta, GA 30332                      Office: Centergy 5212