Found in a European magazine from the 90s, this circuit emits beeps that are several seconds apart to indicate that a device is on. The transducer is a ceramic or crystal capsule.
Found in a 90s R-E Experimenters Handbook, this circuit amplifies signals from 100 Hz to 3 MHz....
This old slide projector control circuit was found in an 80s Hands On. The circuit uses modern...
This circuit is from Motorola documentation, but can be implemented with virtually any...