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.
We found this circuit in an old documentation. The indicated solenoid is of low current type,...
This commercial circuit of 3 transistors was found in Japanese documentation from the 1960s. The...
This circuit was found in National Semiconductor documentation from the 90s. The circuit uses two...