Automotive Tachometer with the 555 IC (CB1419E )

  This circuit from a 1978 American publication is used on vintage vehicles that still have contact breaker where the input is attached. The MC1555 is the Motorola version of the time of the known 555. The instrument is 50 uA and the setting by R7 can be a trimpot of 470 ohms. Non-standard values of resistors can be approximated.


Circuit Bench