We found this precision circuit in a manual from the 80's. The operational amplifier is of a common type at the time, and equivalents can be tested. Transistors are general purpose types.
This circuit is from an Electronics World of 1967. The circuit slows down the activation of a...
This circuit for analog TV was found in a 90s EDN. The integrated circuits used are from that time...
This circuit allows the use of a milliammeter in the measurement of low frequency alternating...