Torchlight dimmer

This circuit was originally designed to control the brightness of an electric torchlight, but may find many other applications because of its high efficiency, ease of operation and ability to control (lamp) loads drawing several amps. The dimmer offers brightness control from nil to maximum in 16 steps by means of a small push-button. When the push-button is released, the selected brightness is retained. One of the most remarkable things about this circuit is that it hardly adds to the battery load, its own current consumption amounting to no more than about 4 mA (at a battery voltage of 3.5 V).