We found this version of the automotive tachometer in a 1980s publication. Variations from other sources appear elsewhere in this section. The indicator is a 0 to 1 mA milliammeter.
This circuit makes use of germanium transistors, providing a fraction of a watt power. It was...
This circuit has appeared several times on this site in different applications. This is from 1997...
This conventional application of the 555 as monostable was found in a technical documentation from...