This circuit was found in a 1968 RCA documentation. The circuit can be designed with operational equivalents. Input signals can be up to 6 V in amplitude and the limitation is 78 dB.
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...