Found in a 90s Popular Electronics, this circuit uses a 741 to generate frequencies from 0.1 to 30 Hz. Observe the phototransistor feedback.
This simple transmitter for the AM range was found in a Popular Electronics magazine from March...
This circuit was found in a 2005 Linear Technology application manual. The circuit can be used...
This circuit was used to regulate the speed of small DC motors of cassette recorders. However, if the...