This low current source without a transformer is intended for applications where insulation is not important. The circuit has a 110 V (120 V) input and was found in old American documentation.
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...