Using a common crystal diode and a 741, this circuit can be used to detect microwaves. The circuit is from old documentation and the switch selects the gains.
This is the conventional astable configuration of the 555 integrated circuit already explored in...
The maximum current of this circuit can reach 500 mA with BD136 and 1 A with TIP32. The circuit...
This circuit was found in a 1980s technical documentation. It tests the inverse characteristics of a high...