This discrete opamp can work in 150V or +/-75V.
The output works in Class A biased 20mA.
The distortion is very low.
The transistors used can all be found at Mouser.
The output works in Class A biased 20mA.
The distortion is very low.
The transistors used can all be found at Mouser.
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Yeahh. I noticed after.
Now, I have added a cap. 10pF. Maybe should be more.
The gain at image is x11.
Now, I have added a cap. 10pF. Maybe should be more.
The gain at image is x11.
There we have the purpose of a forum like this.
Most of are not professionals in this branch but we like to see a lot of amplifier topics.
We learn both from ready tested amplifiers in production or post production but at least i learn just as much from not ready thought ideas.
And how we bring them to work safely.
Most of are not professionals in this branch but we like to see a lot of amplifier topics.
We learn both from ready tested amplifiers in production or post production but at least i learn just as much from not ready thought ideas.
And how we bring them to work safely.
Now, the question is what to use this opamp for.
I can think of using it in a single high power supply for regulating the supply rail.
This would be in a valves/tubes amplifier.
The use is not only for very high voltages.
It can work down to 20V or so.
I can think of using it in a single high power supply for regulating the supply rail.
This would be in a valves/tubes amplifier.
The use is not only for very high voltages.
It can work down to 20V or so.
For a tube amplifier, one “regulates” the supply with a stack of zener diodes, a capacitor, and a follower. Op amp precision is rarely needed. For a DC bias servo it might be just the ticket. Some of us are working on tube amps with crazy power, using toroidal output transformers. You do want to keep the (unbalanced) DC out of those.
That yields into a dynamic (approx) 1.352mW @ 8Ω pure class A.
[ (2*20mA^ / 2*√2)^2 * 8Ω ]
Don't turn the volume pot to much over 7 o'clock, or the cross switching distortion kicks in.
(D1 -- 3 / U5--U8)
You forgot to mention security glasses as being mandatory before testing this "design".
150V is too much for the 2N5401/5551 VAS and its CCS wich dissipate 0.225W each while R13 take 0.45W,
also the VAS driver has no current limitation and 10k is too high to neuter the VAS parasistic ICB current,
the whole is a recipe for a disaster.
150V is too much for the 2N5401/5551 VAS and its CCS wich dissipate 0.225W each while R13 take 0.45W,
also the VAS driver has no current limitation and 10k is too high to neuter the VAS parasistic ICB current,
the whole is a recipe for a disaster.
So it will act just like an IC op amp. No margin for overvoltage. Run it on regulated +/-75V and it’s right at Vceo rating, go to +/-80 and poof. Maybe. The other important spec: Output short circuit duration: zero.
Maybe compromise and make the whole damn thing out of A1381/C3503, except the MJE15032/3 pair.
Maybe compromise and make the whole damn thing out of A1381/C3503, except the MJE15032/3 pair.