This circuit allows you to vary the duty cycle without changing the frequency. An interesting application for PWM controls. The circuit is from a Radio Electronics magazine from July 1985.
This circuit sensor is an NTC with a resistance of the order of 2k. The SCR can be from the TIC...
The load current can be adjusted up to about 1 A. The transistor can be TIP32 or TIP42. The...
This oscillator with common general-purpose transistors appeared in Radio Electronics magazine in...