Two-tone solar buzzer (CB20493E)

This circuit was found in a 1991 publication. The transistor can be a general-purpose type.

5 to 15 V Variable Power Supply using the 7805 (CB10291E)
This circuit was obtained in a 1989 English magazine. Despite using a fixed 5 V regulator, it can...
Digital Phase Control - Digital Dimmer (CB13876E)
With this circuit we can control the power of an engine or the power of a resistive load from a...
RF Detector Probe (CB4129E)
This basic circuit can be used in signal followers and other applications where an RF signal is to be...