Using a MAX644 this circuit was found in the April 1989 issue of Radio Electronics magazine. The circuit is for a 5 V voltage and 50 mA current output.
This circuit of a 1978 American publication monitors a telephone line by triggering a relay. The...
Found in 1965 General Electric technical documentation, this half-wave circuit controls shunt type...
The power supply shown in the figure provides voltages between 0 and approximately 15 volts, with...