This variable frequency circuit was found in a Popular Electronics from the 90s. The circuit outputs to a small speaker and can be powered by voltages as low as 3 V.
In this circuit the regulation is made from a circuit in the LED cathode. The configuration is...
The design of this reader is truly unprecedented, as it allows the replacement of a common reactor in...
This circuit originally appeared in a publication of 1997. With the changes, the circuit can be...