This circuit was found in an American 1980s documentation. Dual FETs can be replaced by single equivalents. Control voltage ranges from 0 to 1 V.
The figure shows three circuits for using headphones in amplifiers with speakers that do not have...
In this charger, the charging current is basically limited by the LEDs. The transformer is a low...
This configuration is from an old integrated circuit manual. The circuit can be applied to modern...