This circuit is powered by a voltage of 4.5 V, being common in radios of the 60's. The circuit is from Mullard's transistors reference manual.
This circuit uses a JFET CA3140 operational amplifier to convert a low frequency sinusoidal signal...
This alternating voltage voltmeter was found in a 1967 magazine. The magazine no longer exists, but...
This circuit was found in an American documentation from the 90's. The circuit is intended for...