This circuit was obtained from an Electronic Design from the 90's. The circuit generates signals at a frequency determined by R and C. The selection by the jumpers determines the PWM modulation.
The diodes of this circuit are for general use and the less common components can be replaced by...
We have already presented this circuit, obtained from manuals from other manufacturers of the used...
This circuit shows how to use a 3-terminal voltage regulator as a low frequency oscillator by...