This circuit was obtained in a 1975 documentation. The maximum frequency depends on the diodes and the FET. Type 1N34 diodes and a FET BF245 can be used for frequencies up to 100 MHz.
This circuit is based on the voltage drop of the diodes in conduction, in the order of 1.6 to 1.7...
Found in older documentation this setting applies to modern components, noting that the power...
This simple timer can be used in many applications such as egg timer. The LED glows up when S1 is...