Found in a 73 magazine for radio amateurs of the 90s, this circuit provides a 2 kV voltage with 7.5 mA of current for HeNe laser.
This circuit was taken from the 1974 Ferranti transistor manual. Transistors are common types at...
This circuit monitors the current of a series of 40 V lithium battery packs connected in series....
This 1970 Philips circuit uses a mechanical counter. The circuit is triggered by a reed switch...