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.
Found in an English publication from 1967, this circuit generates 5 kHz signals with harmonics that...
This circuit was found in a 1991 publication. The transistor can be a general-purpose type....
This circuit was obtained from an English magazine from 1985. The N414 is a complete, not easy to...