With the BD439/BD440 or BD441/442 pair you can run up to 4 amps. Gain starts dropping fast beyond 1A.
i already ordered a bunch of bd139/140 although they should be fast enough for class b operation
That mean you need drivers.
If you want driverless good for more than an amp use D44H10 and 45H10. Just don’t raise the supply voltage too much because power handling above 15 volts goes to hell in a hand basket. That puts the upper limit around 30V, maybe a bit more but don’t push your luck. But they are very linear. If you want to raise the voltage, MJE15030/31.
If you want driverless good for more than an amp use D44H10 and 45H10. Just don’t raise the supply voltage too much because power handling above 15 volts goes to hell in a hand basket. That puts the upper limit around 30V, maybe a bit more but don’t push your luck. But they are very linear. If you want to raise the voltage, MJE15030/31.
I am sorry to hear, but don't give up! Looking at the schematic of post 93, try adding an emitter resistor to Q1. Even a small value (22 ohm?) could help stabilizing DC current through it and the output stage.
Even better, I think, would be to let the biasing diodes make contact thermically with one of the output heatsinks.
Even better, I think, would be to let the biasing diodes make contact thermically with one of the output heatsinks.
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Diode-connected BD139’s (or any iso pack TO-126 or TO-220 that has decent gain at handful of mA). Or for a slightly lower Vf (if needed) darlington diode connected BD139’s. The collector current of the first is the base current of the second. Base-emitter resistor on the second can be used for trim.
thats also an idea. either way my circuit was more or less a simulation and if 100 low power to-92 transistors cost 1.50$ then i dont see a point in reducing the transistor quantity
I have somewhere an old finnish design from 70's which I made around 40 years ago. Almost same like @No ideas , must find this paper. Amp also exist somewhere, was using BD135/136 and maybe BC337 as driver.
Here is first try for power supply, uses mostly same parts like amp and some generic 19V laptop power supply.
6V2 in series with Q2's Vbe voltage gives stable Vref. R6 can be used to adjust output voltage. Nothing special. GE Transistor manual's from 60's have similar, but no N_jfet's in this book.
Here is first try for power supply, uses mostly same parts like amp and some generic 19V laptop power supply.
6V2 in series with Q2's Vbe voltage gives stable Vref. R6 can be used to adjust output voltage. Nothing special. GE Transistor manual's from 60's have similar, but no N_jfet's in this book.
Heatsink is quite hot after 12 hours power on. Transistor Q4 case is around 30 degrees Celsius which is not too much.
This powers up only one amp. Second amp needs second reg or much bigger heatsink. Better to use one reg for one amp.
This powers up only one amp. Second amp needs second reg or much bigger heatsink. Better to use one reg for one amp.
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One correction for message #134. Can't modify it no more.
C1 / 0.1µF is non-polarized polyester or polyprop plastic capacitor.
C1 / 0.1µF is non-polarized polyester or polyprop plastic capacitor.
That circuit is well enough.
The amplifier is not the final highend and can have a simple regulator
The amplifier is not the final highend and can have a simple regulator
the extra transistors would be better spent on paralleling the outputs and making the voltage higher