This circuit was found in the July 1994 issue of Electronics Now magazine. The relay can be rated at up to 12 V and 100 mA. The transistor is a general purpose transistor.
This circuit has a gain of 10 for DC signals. The circuit is from a Radio Electronics from May...
Using only discrete components, this circuit can control loads up to 8 kW. SCRs should be...
The current accross the LED as function of the resistor value is given by the formulas. The...