This circuit is from the time when cars used contact breakers. This 80's version measures the dwell angle of the contact breaker for dwell adjustment using an era integrated circuit, the LM3917.
This circuit locks when the sensors are opened. The relay can be 6 or 12 V depending on the power...
This is a conventional differentiator configuration with operational amplifier. In principle any...
This circuit should be used with low frequency signals only. The circuit is from a documentation from the...