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Nicho 24th January 2013 07:56 PM

OC44 Yellow Jacket Pinout
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I have acquired what I believe to be a yellow jacket mullard oc44. which appears to has a red dot at the top but not next to a pin. It comes from a radio. The centre pin is bare wire and the two outside pins are covered with (removable) insulation; one pin has white insulation (on the side of the oc44 with a black stripe), the other has red insulation. Can anyone tell me which pin is the collector, which the emmitter, and which the base,



Nicho 24th January 2013 08:15 PM

or how to (safely [for the transistor]) test to determine...

Enzo 25th January 2013 12:07 AM

Are the legs evenly spaced coming out the bottom? Or are they in an arc? Look at a more modern metal small transistor, if you look at the bottom, three legs are in a circle with a space where a fourth one would have been. Kinda like this:

Bibliophile 25th January 2013 12:30 AM

OC 44, Tube OC44; Röhre OC 44 ID33607, Transistor

Bone 25th January 2013 10:11 AM

Base is normally the centre lead on all Germanium Transistors. The Collector will normally be the marked lead so that should be the one next to the stripe on the sleeve.

Nicho 25th January 2013 02:06 PM

Thanks for all the help. I will go for the one next to the stripe being the collector. It's separation from the center pin is also a little greater, which also fits with Bibliophile's link. One more question, how likely am I to damage it if I get it wrong and the collector up to the positive of a 9V battery?

Bone 25th January 2013 08:28 PM

Well I wouldn't connect it up without testing it first. Have you a DVM with a transistor tester in it? What circuit are you using it in?

Nicho 25th January 2013 09:10 PM

I was going to put it in this one

tinitus 30th January 2013 08:06 AM


Originally Posted by Nicho (
I was going to put it in this one

:up: please let us know how it goes

Nicho 31st January 2013 11:31 PM

Well I appear to have killed it. The way of connecting discussed above was correct. I was getting a readout which converts to 12uA leakage (is this possible, it seems strangely low) and a hfe of 70. Then I decided to messure current through the 2.2M resistor (apparently foolish). The transistor got very hot and is now basically an open circuit between collector and emitter. Oh well. Some you lose.

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