High Gain Yellow Jacket OC44's

Frequently asked question on transistors: types, substitutions, how to test, use and misuse them.
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agreco1489
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Post by agreco1489 »

Hey guys just picked up some NOS oc44's, hfe's are 138, 221 both with 0 leakage, any ideas what I can use them for? Thanks

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agoldoor
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Post by agoldoor »

I'd doubt with gains that high that they actually have zero leakage. I would guess from those measurements that you're using a Peak Atlas DCA55? It's been mine and others' experience that the Peak will always show zero leakage for OC43, OC44 and OC45. I'm not sure exactly why this is... anyhow, I just wanted to give you the heads up... and like everyone else says... "use your ears."

But as far as what to use them for, in general yellow jackets are higher gain than other OC44's (perhaps this is what the yellow jacket indicates? I know that some Mullards are color coded with dots, and there are blue and orange jacketed OC45s...) I'd use them in a high gain boost. There are lots of circuits out there designed for just this kind of high gain germ

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phibes
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Post by phibes »

My peak has shown leakage for OC44's and OC45's, I've never heard that about those transistors before. Some of the old Mullards just ain't that leaky. The leakage is probably too low for the peak to calculate. I think people are too used to buying cherry picked germs with high leakage that they freak when they find something very very low leakage.

You could use em in a Rangemaster. You'd prolly have to adjust the bias though. Drop the 470K resistor for a 500K trimmer and you should be able to find the sweet spot. Bastardize up the circuit and what not.
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beedotman
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Post by beedotman »

Mullards OCxx have usually low leakage. I've got pair of OC42 with gains around 130 without leakage.
Those OC44 could work nice in some high gain fuzz circuit - Meathead or Oracle for example.

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