LPB Questions

[5150]

Two quick questions on the circuit I thought was too simple to screw up:

First (I'm using the schematic on GGG) if I'm getting no signal boost (i.e. pot goes from mute to unity, not boosting at all) but still the same signal, what is more likely - improperly wired input jack (possibly running as a passive circuit?) or a blown transistor (2n5089 - I'd expect this to not transmit the same signal, though) given that not too much else can go wrong?

Second, will a 2n2222 Darlington pair work on this circuit?  I've read that they have massive gain, but I don't want to blow anything up or get a cheesy, lo-fi sound.

Thanks,
Jeff

[petemoore]

Two quick questions on the circuit I thought was too simple to screw up:

First (I'm using the schematic on GGG) if I'm getting no signal boost (i.e. pot goes from mute to unity, not boosting at all) but still the same signal, what is more likely - improperly wired input jack (possibly running as a passive circuit?) or a blown transistor (2n5089 - I'd expect this to not transmit the same signal, though) given that not too much else can go wrong?
  >>possible, but I doubt the tranny's blown.
Second, will a 2n2222 Darlington pair work on this circuit?  I've read that they have massive gain, but I don't want to blow anything up or get a cheesy, lo-fi sound.
  >>one oughtta do it, that or the 2n5089...
Thanks,
  "What to do when it doesn't work"...check it out near top of threads.
Jeff

[amz-fx]

First (I'm using the schematic on GGG) if I'm getting no signal boost (i.e. pot goes from mute to unity, not boosting at all) but still the same signal, what is more likely - improperly wired input jack (possibly running as a passive circuit?) or a blown transistor (2n5089 - I'd expect this to not transmit the same signal, though) given that not too much else can go wrong?

Second, will a 2n2222 Darlington pair work on this circuit?  I've read that they have massive gain, but I don't want to blow anything up or get a cheesy, lo-fi sound.

Post the dc voltages from each of the transistor legs to ground and we can tell you what is happening.

The 2N2222 will work but it is a normal NPN and not darlington.  You are better off using the 2N5089 as it is a lower noise device.

regards, Jack

[5150]

"The 2N2222 will work but it is a normal NPN and not darlington."

I know, I just read about the Darlington pair stuff at a bookstore and was wondering if stacking two transistors this way would be a good way to get more gain.  Are these things ever used anymore (I know the transistors of Darlington's day were hot stuff if their gain was about a hundredth of today's transistors), or are they of some use... somewhere?

Jeff