This circuit was obtained in an old Elektor and can be adapted to use white power LEDs. The transistor must be equipped with a heat sink. The circuit has a battery charger.
This circuit is based on the HA1311 integrated circuit, common at the time the article was...
This circuit consists of a low-pass filter for the frequency of 440 Hz. The filter therefore...
This circuit was obtained from a Radio Electronics magazine from June 1969. The circuit uses a...