This trivial but very efficient circuit protects a run-acid battery (12-in opposition to solar battery otherwise car battery) critical of overcharging by a solar module once the thing light is too brainy otherwise lasts too stretched. It does so by energizing a fan, opening by a low tempo once the voltage is approximately 13.8 against and rising to jam-packed speed what time the voltage exceeds 14.4 versus (full-charge voltage). The threshold voltage (13.8 in opposition to) is the sum of the Zener diode voltage (12 V), the voltage across the IR diode (1.1 against), and the vile-emitter voltage of the 2N3055 (0.7 against). stylish contrast to circuits using relays before IC amplifiers, the circuit has a gradual switching characteristic, which avoids relay rant and the constant switching on and rancid approaching the switching site produced by a ‘unbreakable’ switching point.
The circuit does not deadlock in the least current by the side of all (sedan power-inedible) under 13 versus. disburse attention to the polarization of the Zener and IR diodes as building the circuit. The transistor essential exist fitted to a warm sink, since it becomes peppery as soon as the fan is not fully eager (next to voltages only this minute beneath 14 vs.). A galvanized bracket from a DIY supermarket forms an ample warmth sink. The indicated element ethics are pro a 10-W solar module. If a privileged-power module is used, a motor with higher rated power requirement plus exist used. The circuit takes benefit of the confident warmth coefficient of the lamp filament. The filament resistance is low by low voltages and increases since the voltage rises. This reduces the hustle of the fan to dodge generating an maddening sound level. The lamp moreover provides a form of finger protection.
If you stick your finger into the fan blade, the lamp directly takes greater than the majority of the power dissipation and light brightly. This considerably reduces the torque of the fan. An ordinary 10-W otherwise 20-W car headlight (or two 25-W headlights indoors corresponding) can be situated used designed for the lamp. Don’t try to trade the LED by two 1N4001 diodes or else the like, replace the ZPY12 by a ZPY13, otherwise fit a succession resistor for the LED. to facilitate would compose the ‘on’ region too well-built.