opamp power booster

Check; did not spell it out that way as the scheme is so rarely seen.

th issue.

Thanks RL, It is indeed the TIP32 that is causing the gain peak. When replaced with a 2N4403 things look much better. Are you suggesting a resistor from base to emitter? 1 k ohm or so?

Hey that seems to help! Should I think about a B-E resistor as path to the output that doesn't have to go through the transistor?

I'll have to switch back to the TIP32 and see how that looks.

Again my thanks, George H.

issue.

Emitter followers are usually fairly predictable. You should probably have an emitter-base resistor on the pass element, local op amp feedback in the 100pF range, and global feedback driven from the actual buffered output, as with a typical audio application.

Only then should you consider tweaking for pass element and load variations.

As this is indeed a 'bipolar' power supply, able to produce both positive and negative outputs, it doesn't make much sense fiddling around stabilizing an incomplete circuit.

RL

of

That is because the BE junction diffusion capacitance is directly proportional to emitter current- and has nothing especially to do with it being a power transistor.

At 200k the TIP32 is going to have some bandwidth issues?

issue.

or

d text -

Hi David,

George H.

issue.

With 2nF local feedback, and a 10K source, most op amps would have a bit of trouble producing gain at 200KHz.

RL

dth issue.

ector

ly

th

oted text -

I can hook it back up again and send you a scope shot. (And only

George H.