This circuit protects galvanometers that are excited by low impedance amplifiers. The circuit is from na old Electronic Design. The components are from the era.
Indicated by Popular Electronics to be used with a car headlight, this circuit can also have...
In this circuit of a 1970s publication, data from the coil to oscillate at the desired frequency...
This circuit was obtained from a Philips documentation from 1968. The transistors can be replaced...