This circuit is better than the previous one in that the control is isolated by a transformer. The transformer has 110 or 220 V primary and 6.3 to 12 V secondary with 200 to 500 mA current.
The range of generated signals depends on coil L1. The circuit was found in old English...
This circuit was suggested by Electronic Engineering in a 1980s publication. The circuit makes use...
This automotive tachometer circuit uses a FET and a 1 mA full-scale instrument. We found it in the...