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.
This circuit was obtained from a 2005 Linear Technology application manual. The circuit is...
The tone produced by this circuit depends on the capacitor and the adjustment of the...
We found this circuit in 1969 American documentation. FETs admit equivalents, as do transistors. The...