This interesting circuit uses a sodion valve that we have already described in an article on the website. The circuit uses several batteries for power. The phone is of high impedance.
This circuit is from the LM101 manual. However, the configuration is valid for other operationals. The...
September 2016 - It can be obtained from Mouser Electronics a kit for developing wireless remote...
The operational amplifier of this circuit can be the 741. The circuit has very low consumption and can be...