Overload recovery

[lndm]

My experience is single ended. I guess the real issue is less of the cathode voltage and more of V_g-k.

[arnoldc]

Oh I see, but thank you for the great post. I'll checkout my single ended amps

[SY]

Originally posted by arnoldc
Indm, can I use just a scope and signal generator to see my amplifier's overload recovery capability or lack of? If so, may I ask how?

Better to use a soundcard instead of the generator. Find a copy of Dazyweb Labs' SG-2102 signal generator software. You can set it up to play a sine wave at arbitrary alternating levels with arbitrary repetition rate. To look at overload, I'll set the higher level to something that will take the amp well past clipping, then the lowerr level at something just below clipping. Varying the rep rate will let you see if the amp instantaneously recovers by watching the lower level.

It takes a bit of squinting and playing with the scope sweep to hit a point where this is easy to see, but trust me, it will only take you a few minutes to find appropriate settings of the scope and software.

[lndm]

http://speech.di.uoa.gr/dsp/program/...rator_2102.zip

[arnoldc]

SY, my problem is that my Acer notebook with RealTek Audio is really crappy and can't even generate a decent square wave with a previous software I tried

Indm, thanks for the file!

Cheers!

[lndm]

Originally posted by Johan Potgieter
they must be PNPs.

I'm not sure I understand the difference between these two versions. I found that for a nominal output (about 3V_p-p), the signal at the cathode was about 3mV_p-p in both cases.

[SY]

Originally posted by arnoldc
SY, my problem is that my Acer notebook with RealTek Audio is really crappy and can't even generate a decent square wave with a previous software I tried

That may be, but for this app, you want sine waves, which sound cards do much better. Getting a good square wave out of a sound card, even an excellent sound card, is pretty much impossible.

[Johan Potgieter]

Indm,

Righteo... I stand corrected; a little quick on the trigger. One can obviously regard any active or power zener as a cell on its own for either polarity - your 2 circuits are the same. I am afraid I was blinkered to my own circuit and perhaps the nicety of a collector directly on the chassis. The 300mV you measured should surely come as close to fixed bias as one would wish for.

I will post my own circuit just for the record as soon as my @%$*# scanner will work again; as said it is pretty standard.

Regards

[lndm]

Originally posted by Johan Potgieter
I will post my own circuit just for the record as soon as my @%$*# scanner will work again

Thanks Johan.