This circuit with two operating modes was found in the September 1989 issue of Radio Electronics magazine. Other operational amplifiers can be used. The power supply must be dual.
We found this 4W transmitter in a Mullard transistor manual from 1960. The circuit is powered by...
The response curve of this circuit has a maximum boost of around 6 kHz. The vertical scale is in...
Using the 555 this circuit was found in a Popular Electronics from the 90's. The circuit directly...