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Help with finding obsolete Motorola 43121 transistor

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New Member
I need to replace this transistor since it has tested bad...
I cannot find a single thing about it anywhere. It has the Motorola insignia and says 43121, then on the back it has 3 color bars, red, silver, and yellow.
Here is some pics of it and also in circuit.. (Q6 on schematic)



I couldn't find it using Google.

Please post the entire schematic.

How do you know it's bust, have you tersted it?

The chances are any small transistor will do.

Nigel Goodwin

Super Moderator
Most Helpful Member
It's a low current 35V odd regulator - what to use really depends what voltage is been fed to the collector.

I'd try a BC107 for a start, but any general purpose NPN will probably do.
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