This receiver for infrared remote control was found in the Philips Databook of 1990, The circuit operates with 5 V and is intended for receiving data.
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...