Hello Maybe someone has simple (the simpler the better) circuit for a low-frequency transistor amplifier with a class D cascade, or can explain how to creat it, I'm going to make it in Microcap? I can only find very complex circuits in internet.
Hello. I try to make first circuit from this article https://www.radiolocman.com/shem/schematics.html?di=152208, but it doesn't work and I can't find what I miss, when make it in Microcap. Input frequence is 10000 Hz and ampletude is 5 V.
Don't expect particularly good results from that circuit. In astable mode the control pin can change the frequency as much as the pulse width and the output is not AC coupled so it shouldn't be used directly to drive a loudspeaker or headphones.
You will get better results if you trigger the 555 from an external fixed frequency and wire it in monostable mode. The 'out' connection should be connected to the load through a capacitor to remove the DC offset.
I cropped your schematic so it looks almost as clear as the original. I do not know why you changed all the R and C numbers.
I think an old 555 timer makes a very poor class-D amplifier.
The principle is to vary duty cycle of pulses (PWM) depending on voltage of input signal.
Here is a class D amplifier, starting with a triangle wave generator (found in the Circuits menu of Falstad's simulator).
Experiment until we discover which is a strategic spot where we can influence the triangle waves. Apply the incoming signal.
Feed the output to a logic gate.
Notice the carrier frequency itself does not change.