This rapid response amplifier uses an integrated one that is not common today but can be implemented with modern equivalents. The circuit is from an 80's manufacturer documentation.
Originally this circuit was indicated to be used in a garage door control, but it can be modified for...
This conventional oscillator with the 741 can be precisely adjusted to produce a 400 Hz signal. The...
This current-limited circuit was found in a Popular Electronics from the 90's. ...