We found this circuit in the 1983 Radio Electronics Special projects magazine. The components are common, and the circuit drives a relay. The power supply must be isolated.
This circuit is from a Popular Electronics from 1993. The magazine is no longer printed, but the...
This oscillator for sinusoidal signals uses a lamp as a stabilizing element. We found it in the...
This amplifier, for millimeters from 0 to 1 mA, was found in a 1957 Raytheon publication. The...