Here is a simple circuit Mini UPS. This circuit 12V, 9V and 5V DC-powered vehicles to operate until a current one for providing uninterruptible power supply (UPS) is. Take the load without spikes or delay when the power supply is interrupted. In addition, backup battery, bench power supply 12V, 9V and 5V supplies as tensions kullanılabilmektedir.ak to avoid draining the battery voltage dropped to 10,5 V for the circuit immediately disconnects the load. LED1 indicator to show a fully charged battery voltage is delivered.
Miniature white LEDs (LED2 and LED3) are utilized as emergency lamps especially during electrical power failure at night time. A common step-down transformer delivers 12V of AC, that is rectified by diodes D1 and D2. Capacitor C1 features ripple-free DC to charge the battery and to the remaining circuit. When the mains electrical power is on, diode D3 gets forward biased to charge the battery. Resistor R1 limits the charging current. Potentiometer VR1 (10k) with transistor T1 acts as being the voltage comparator to indicate the voltage level. VR1 is so adjusted that LED1 is in the ‘off’ mode. when the battery is completely charged, LED1 glows indicating a maximum voltage level of 12V.
source : Mini UPS Circuit
