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Vintage threads from the first ten years

AC128 Germaniums

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5/18/1997 7:54 AM
Greg Soh	AC128 Germaniums Hi, I stumbled across this place in Singapore that sells the AC128 Germanium transistors at about USD3.00. I will probably be getting some, so does anyone want some, I can help you out. It gets cheaper if you buy lots. More than 25 will cost USD2.65 and more than 100 at USD2.35 and so on.... Regards, Greg

5/19/1997 3:30 AM
Dave Harris	FYI. If you are in the UK you can get AC127/128 from RS Components for about one pound sterling. DH

5/19/1997 9:16 AM

Great news on the availability of this part. One caution - buy several more than you actually need.
I bought a couple of batches of these things for making Fuzz Face boards, and I found that the gain
varies all over the map.

You want gains of 75 to 115 for a good Fuzz Face. I have found that between one third and half of the ones I've received fall either too low - hfe from 21 (!) to 75, or over 115 - some as high as 550. The highones are not really high gain, they're leaky. I test gain with an ordinary DMM
with a gain test.

5/19/1997 4:46 PM
Mike Oriente	Would you explain how to test these with a DMM? Thanks

5/20/1997 5:34 PM
R.G. Keen	You have to have a DMM with a transistor test setting - I may have forgotten to mention that. It's common on a lot of DVM's. Some don't, unfortunately.

5/20/1997 7:52 PM
Mike Oriente	Mine does, but how is the test done?

5/21/1997 11:22 AM

On mine, you just set the meter to NPN or PNP, insert the transistor into the transistor socket on the meter, and read currrent gain directly. Yours may be different, although all of them I've seen work like mine. You have to get the leads in the correct holes and the polarity correct for this to work, but other than that, just read the numeric gain. Maybe the instructions that came with your meter could provide more detail.

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