This circuit uses an unusual sensor nowadays, but the configuration can be adapted to more modern types, as well as the operational amplifier. The circuit is from an 80's documentation.
This circuit converts a high impedance signal into low impedance. The circuit has unit gain and...
This project came out in an article of mine (Newton C. Braga) in the Popular Electronics magazine of...
This variable oscillator with crystal was found in a Popular Electronics of the 90s. The circuit uses...