Using the 2N2646 this circuit was found in a Radio Electronics magazine from July 1968. The transistors are from the time and the lamp can be replaced by a high-power LED in a current version.
This circuit was found in old documentation but uses components that are still common. The circuit...
This transmitter kicks in when the microphone picks up sound. This sound then modulates the signal...
In the figure we have the way to connect an LED on the output of a power source to indicate the...