Using a 709 integrated circuit this circuit was found in the June 1972 issue of Radio Electronics magazine. More modern operational equivalents can be used. The power supply is symmetrical.
This circuit detects traffic problems on a miniature railway by triggering an alarm. The circuit was...
This circuit is from European 90s documentation. The integrated circuit used is not very common...
This oscillator, from an old Argentine publication from 1973, uses the inductance of the 500 ohms...