Measuring Germanium Transistors with the DCA75

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Күн бұрын

Пікірлер: 8

@darrylcarstensen5448 4 жыл бұрын

Paul, I have been going through all of your older videos and watching them again. Wow, you really have a lot of great content. Thanks for sharing your knowledge.

@JurekPrzezdziecki 4 жыл бұрын

Super useful information. Great to hear someone's experience. I have got about 150 of 2SB77, 2SA210, 2SA17 and 2N397.

@RobbyMatthias 9 ай бұрын

I have an older 'transistor-testing' meter that I call the 'ego-deflator'! When the needle stops hopping around you get a very good idea of the 'hfe',which is usually a 'big let-down'!Ha! Thanks' for all of your post.'Super-informative'!!!!🍻

@6StringPassion. 2 жыл бұрын

That magic pyramid is a useful visualization for remembering all kinds of equations.

@dunk8157 Жыл бұрын

I sat down with the Keen circuit and tested about 50 random transistors, one of the main things I noticed is that they all took a few minutes to settle down to a consistent reading. Not sure why, reminded me of old TVs and osciloscopes where you had to let them "warm up" before using them. The thing is they all gave a higher hfe reading when first switched on, and the hfe would then drift down over maybe 5 minutes before it settled, the leakage would go down too. The DCA testers run for a second or eve less I think, so not long enough to get a good reading in my opinion. I could not agree more that the people selling transitors do not really know enough about it and just run them through a machine and think thats all there is too it. Also I know transistors have different gain at AC vs DC so thats another thing! Maybe thats why some that measure low hfe at DC sound good in an actual fuzz. My view after doing the testing is that there is nothing to compare to reading the voltages or currents accurately with a DMM, and then using excel to do the maths. You can then measure the exact voltage across the junctions of the transistor and if you know the resistor values you can work out the exact base current, and add that in your excel calacualtion to get the exact gain (well within the margins of your DMM which usually are very good these days at less that 1% error) the RG Keen circuit uses assumptions here so there is a margin for error. I suppose this is something that could be imprved apon forever and there is a limit to how far you can go. I do wonder about testing it with a AC current though, say 1khz.