This current meter with many scales was found in a 80s American documentation. The operational amplifier is from that time, uncommon nowadays.
This circuit was found in the Spanish magazine No longer in existence, Mundo Electrónico, in a...
This circuit that has a response from 10 Hz to 700 kHz was found in Philips documentation from 1968. Dual...
This simple sweep generator circuit has been found in older documentation, but can still be easily...