This circuit was found in the June 1995 Electroics Now magazine. The relay should be a sensitive type with up to 100 mA trigger current.
This circuit can measure frequencies up to just over 1 MHz and uses CMOS technology. The circuit is...
This variable oscillator was found in a Mullard transistors manual from 1960. The resistor R5 is...
This circuit, from a 1988 documentation, consists of an automatic temperature control using an NTC...