We found this circuit in a 1957 Raytheon transistor publication. The circuit can be assembled with more modern transistors with minor changes. The handset must be high impedance magnetic.
Found on an 80's Elektor, this circuit uses common components, being the diode a general purpose...
April 2017 - The new Recon Jet ™ Pro which is Smart Glasses from Intel® can be obtained from...
This circuit was found in an integrated circuit manual from the 1980s. The circuit can be designed...