This circuit appears elsewhere in this section and on this site. The circuit generates a linear ramp having been found in 1980s documentation. The transistor is a general purpose type.
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...