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.
As we have explored on this site many times, a 2N3055 without the cover works like a low yield...
In the figure we show a configuration for a crystal controlled overtone oscillator using a...
This circuit was obtained from an English magazine from 1976. What this circuit does is start from...