Battery Juicer
More and more electronic devices are portable and run off batteries . It is no surprise, then, that so many flat batteries find their way into the bin and often far too early. When a set of batteries can no longer run some device for example, a flashgun the cells are not necessarily completely discharged. If you put an apparently unserviceable AA-size cell into a radio-controlled clock with an LCD display it will run for months if not years. Of course not every partially discharged cell can be put in a clock. The circuit presented here lets you squeeze the last Watt-second out of your batteries , providing a bright ‘night light’ - for free! The circuit features a TBA820M, a cheap audio power amplifier capable of operating from a very low supply voltage. Here it is connected as an a stable multivibrator running at a frequency of around 13 kHz. Together with the two diodes and electrolytic capacitor this forms a DC-DC converter which can almost double the voltage from between four and ...