Transistor matching - my results

[Roy Tate]

I just thought I would share this with the rest of you.

I downloaded a transistor matching schematic from someone's
web site (info was posted to Synth-DIY earlier).  The schematic
originally came from a Moog service manual.  I don't have a 10V 
power supply hooked up yet (I have a +/- 15V linear supply, but
it's not hooked up.)  So I used 4 x 9 volt batteries in pairs as a
+/- 9V supply.  I tested and found that all of the transistors 
(or at least the first 7) matched perfectly!  They would still have to 
be epoxied together to keep them at the same temperature when 
they are on the board.  It looks like transistors from the same 
production lot are very likely to match.  Here is the test data for 
my first matching session:

Transistor #1	4.574 V, retest after #7	4.571 V
Transistor #2	4.574 V
Transistor #3	4.573 V
Transistor #4	4.573 V
Transistor #5	4.572 V
Transistor #6	4.571 V
Transistor #7	4.571 V

You'll notice that the voltage was dropping as I went.  I suspected
it was just battery drain, thus I retested several transistors and 
they all matched.  I showed Transistor #1's retested value to
illustrate this.  These values don't mean much in themselves, as
they depend on battery strength, the exact resistors and Op-Amp
I had in the circuit, etc.  BTW, I was using a Fluke 8060A digital
meter.

Peace,

Roy Tate
roytate at ionet.net