This interesting circuit was found on the Internet and is based on the 555. The circuit uses power MOSFETs that determine its output. No information about the transformer was provided.
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...