Found in an old publication, this is a transmitter with a spark coil. The high frequency oscillations of the high voltage spark generate the signal thrown at the antenna.
This VCO or Voltage Controlled Oscillator uses common components. TR1 can be a BF245 and TR2 a...
This 555-based circuit was found in the August 1976 issue of Radio Electronics magazine. The tone...
The integrated circuit of this project is not very common. The circuit is from 2003. This circuit is...