Used by radio amateurs to accompany telegraphic transmissions, this circuit generates an audio tone. The power comes from the transmitted RF signal itself.
With this luminous remote control, which we found in a 1990 publication, using a flashlight you...
We found this circuit in a 1967 Electronics World. The circuit can be designed to control other...
This circuit can be used in a signal level indicator with LEDs. The circuit is from an Electronics Now...