Pulse Width Modulation

[Rumcajs]

Hi all,

i m designing and building an PI-detector with modulated pulse width. Here is an schematics from oscillator & power circuit:

[Rumcajs]

The 555 modulation already known from DC-motor drivers.
the output without modulation:

[Rumcajs]

When adding signal from modulator circuit to 555 pin 5:

[Rumcajs]

The settings resistor values in the braces, for example [118k].
Known problems:

1.) 555 will be generate many harmonic, and sometime starting the any harmonic fequency -- with or without modulation. I m dont known, why? Maybe my IC is wrong?

2.) The positive modulation voltage increase the pulse width, must be 3k3 shorten and qood heatshink with cooloer! Must be reduced the 600 pps...

3.) The op-amp modulator is working, but i m checking the another (555, 339, ect.)
Unfortunatelly the 565 waweform-gererator is unavailable in the Absurdistan.

4.) The lower pps will be generate the longer pulse width: see last picture (253 pps).


No PCB!
It is an proto... if working, i m removing from circuit to all stupidism, and after making an LAY file.

Brg

Rumcajs

[Rukbat]

1.) 555 will be generate many harmonic, and sometime starting the any harmonic fequency -- with or without modulation. I m dont known, why? Maybe my IC is wrong?

There's nothing wrong - a square wave is a sine wave with an infinite number of odd harmonics. The only thing "wrong" is that you expect a signal that consists of harmonics to not have any.