2n3904 isn't 2n3904???

This is weird.
When I replaced a 2N3904 in my superregen with a brand new 2N3904 from a different manufacturer, then it does not work. However, if I replaced it with a 2N3903, it seemed to work again. The old 2N3904 is not damaged.

Is it true that certain manufacturers make bad transistors?

Maybe you just got a bad transistor.

mstechca said:

This is weird.
When I replaced a 2N3904 in my superregen with a brand new 2N3904 from a different manufacturer, then it does not work. However, if I replaced it with a 2N3903, it seemed to work again. The old 2N3904 is not damaged.

Is it true that certain manufacturers make bad transistors?

Click to expand...

I would not say "bad' transistors, just the specs being a little different. If you ever had cause to match the gain of two identical transistors you will find it can take a handfull of transistors to find two that match.

Maybe your circuit is critical in a certain transistor parameter and your brand new 2N3904 was not up to it.

MStechca,
Maybe your "bad" transistor is too good for your circuit.
A 2N3904 is guaranteed to have a current gain from 100 to 300 at a certain voltage and current.
A 2N3903's current gain is only from 50 to 150 for the same conditions.

I always design transistor circuits to use negative feedback so that any transistor of the one I selected will work.

Don't call a good transistor bad, when the circuit is bad.

i agree with Audioguru. any design that is dependent on the beta of a transistor is bad. buy a good electronic circuits book and learn about feedback in BJT amplifiers.

The library is full of good theory (for free), the internet is not.