Which gain testing method is more accurate

[gutsofgold]

I don't understand enough about transistors to really see what each method does and how they might be different...

[R.G.]

They're both equally accurate - which is not very.

They both serve as an indicator of one specific quantity, DC current gain. The problem is not so much with the method being accurate or inaccurate. It is that gain changes with temperature and collector current. If either method was **perfectly** accurate, they still could not come up with a single number for gain. The best that can be done is a family of curves for gain as temperature and current vary.

Bottom line - don't get hung up on which is the most accurate method.

[ayayay!]

So how accurate are the ones built into DMMs then?  Let's say cheap-to-average DMMs for our sake. 

[gutsofgold]

I don't need accurate anyways, just need to know if germanium transistors are too leaky and a ballpark on the gain. I guess the small bear one will be easier with the single 1M resistor.

[R.G.]

About the same, and for the same reasons. It's not the measuring method that's an issue - it's that you're measuring a varying quantity. Then the measurement accuracy of the instruments/setup on top of that.

Come to that point, how accurate ARE your DMMs? For cheap to average DMMs, they're probably not calibrated to NIST standards and traceably so.

I tell you again, don't get hung up on which is the most accurate measurement method for DC current gain. Most DMMs are usable as indicators, not measurement devices. I had to sit through a course on instrumentation which I suspect has been dropped out of the EE curriculum by now. There are formal definitions of accuracy, precision, and repeatability - which are not the same thing - as well as resolution, which is itself different.

Seriously - if you're making effects, believe whatever number you get, and know in your head that a different meter, test setup, or temperature would make it a little different. Don't get hung up on the accuracy of gain measurements.

[Sir H C]

If you want accurate you need a curve tracer and a a way to vary temperature.

Here is a curve tracer (it is one of the front modules for the tektronix scope):



Too bad I didn't save the themospot for temp testing.

Still this is more information than you need for rock and roll.