Designer2
Thanks for your input. But there is something in my design requirements that I have been trying to incorporate along the way. If I go back in time say 30 years, will replacement parts be available, should I have a malfunction?
About the only Integrated Circuit that I feel safe with is the 555 timer. So with that design criteria, I've been selecting designs that are using components that were around through that time span.
Several months ago I found this basic transistor amplifier circuit that I've experimenting with. Since I've learned the hard way that if I don't breadboard the circuit first, it usually ends in disappointment.
I think there are fictional writers out there posting fictional schematic diagrams.
Anyway this basic amplifier circuit I found actually worked. Of course it did require minor tinkering to get the performance I was looking for.
I had to remove C2 capacitor. R5 is the gain resistor and has to be tuned for different power supply voltages. And R6 may need adjustment if any uneven clipping occurs during full output. But other than that, this circuit is very adaptable to whatever transistors you have available. The thing that interested me the most was that as pictured, there appeared to be no visible distortion from 15 Hz to 100 KHz. The claimed output as pictured is 50 watts with a +-35 volt power supply. Or 80 watts with the optional output transistors. So this is the power amp I just completed today. I made two of them, and configured everything into a metal case.
The part I was talking about earlier is the two transistors at the front of the schematic are configured as a differential amplifier. The same function as an op amp. I've substituted 2N2907 and 2N3906 transistors in the front end with no change in performance.
Since this circuit is so adaptable, I've been looking into higher voltage components. They are available. I could conceivably get the output up to 300 watts using the same circuit. And it might be cheaper to do so.
I've been thinking about making a transformer-less power supply from the 120v ac line. I have a batch of 1000volt 10 amp diodes. Just a couple of those and a couple of large filter capacitors and I believe I could have a +-60 volt power supply straight from the power line. But I've never done this before, so if you see anything of note about what I have planned, say something.
Also the printed circuit boards are also a hobby of mine. I use the positive etch method. And a very easy to use software program that I have been using for over 10 years now.
I just have to run my amplifier through some scope checks to make sure everything is fine. And then off to a transistor based or 555 timer based ramp wave generator.