The indicator for this circuit is a 0 to 1 mA milliammeter. The operational is from the 70s, when the circuit was published. Modern equivalent can be used.
This oscillator uses a small transistor amplifier or radio output transformer. We found it in a...
This small transmitter circuit has a range of about 100 meters, and the antenna must be connected to...
In the figure we have the way to connect several 555 to obtain sequential operation. The component...