Yes - it is a DC feedback resistor.I found this low power class AB amplifier schematic and did a sim. Is resistor RF a DC negative feedback
resistor? How would a designer decide what value this resistor should be?
LOL. Now that we have established that the designer wasn't real, what would the appropriate circuit be?Yes - it is a DC feedback resistor.
A real designer wouldn't use that circuit, as it would set the DC level at Vbe+V(RB2) without the ability to change it.
Thanks Mr Chips. I will try this out.
Hi AGYour circuit is biased wrong and has a very low gain.
I fixed it but the transistors are overloaded.
I improved it with more powerful little transistors.
Thanks. I ran a sim and there is 7% THD (some crossover) and very little output (240 μW).
The ouput is 125mW and the THD is 6%? Wasn't this circuit a 1 watt amplifier?R1 increases the input impedance so it is not simply the base-emitter diode of Q1 (as a signal rectifier) and roughly sets amplifier gain.
Your Sept11 schematic has a very low input level of 38mV peak and with the gain of only 10 times, the output power is only
I used simple calculations and a bit of cheating for resistances and capacitances.
No. The output of my amplifier on post #15 is undistorted 4V peak which produces an output power of 2W peak which is 1.0W continuously into the 8 ohms speaker. The distortion is fairly low for such a simple amplifier.The output is 125mW and the THD is 6%?
Here is what I get. Don't know why mine is different.No. The output of my amplifier on post #15 is undistorted 4V peak which produces an output power of 2W peak which is 1.0W continuously into the 8 ohms speaker. The distortion is fairly low for such a simple amplifier.
Years ago I built an amplifier for a TV. I used an LM390 amplifier IC that is similar to an LM386 but it uses bootstrapping for a higher output voltage swing. it produces 1.13W into 8 ohms at low distortion with a 10V supply.
In your post #15 you had a 0.5 volt input signal and a peak output voltage of 4.0. My circuit isYour amplifier has a 0.5V peak input signal which causes the output to have bad clipping.
My amplifier in post #6 has an input of 0.38V peak then its output has no clipping.
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by Robert Keim
by Robert Keim
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