I've got a question that I know has probably been touched on a few times, but I've searched a lot and can't seem to find an answer, so please don't get angry at me for asking this. I understand that Ge transistors leak current from the Collector and Emitter, even if there is no power supplied to the Base, which is why its hard to find good ones. Now, what is considered to be the limit for acceptable leakage in general. I've read on GEOFx about creating a tester, and have read posts from R.G. that says its best to say 300uA or below, which is .300mA, but I've read that people using transistors with higher leakage in some circuits like fuzz faces no problem.
I ask cause I recently purchase some Ge transistors have some that have great hfe, 160-320, but leakage of 320-450uA. So I'm not sure if they are really usable in a circuit, or if I'll need to find other uses for them.
So two questions. One, what is the cutoff for acceptable leakage in a Ge transistor so that it is useable in a circuit. Two, how does the leakage of a transistor affect a circuit? Basically, if you use a leaky transistor, what problems will it cause.
Let me the first of what is most likely to be many to respond with this.....
Try it and see if you like it! ;D
You never know until you try them out. You can measure for leakage all you want but the bottom line is that it is all in the ear of the person using them.
http://www.diystompboxes.com/smfforum/index.php?topic=27077.0
Im guessing you measured the leakage and gains using the geofex method?
I actually bought a dca55, but will be also testing using the geofex method to double check.
Rough-check: multiply the leakage current times the collector load resistor, and compare to the supply voltage.
If I am building a studio line-driver with 500 ohm collector load, 1mA is "nothing" and 10mA is "small adjustment".
I probably have over 12V supply.
1mA in 500 Ohms is 0.5 Volts. This much-smaller than my 12V supply. I probably want to aim for near 6V. So I will have to "add leakage" with appropriate base bias resistor(s).
10mA in 500 Ohms is 5 Volts. This is less than half of my 12V supply, but so very close that the circuit will "work" without any base bias resistor(s). (Until it gets hot.) (Or I try to build a duplicate.)