In this article we are going to inestigate a simple Uninterruptible power supply (UPS) using 12V battery. We are going to explain these UPS c ircuits very simply that a new electroinics student can understand. These UPS circuits can be used for operating a specific appliance or load.
Simple Uninterruptible Power Supply
In this circit idea we can built at home with uisng most ordinary or comon used components to produce a reasonable output. This simple UPS circuit can be used not only usual electrical load but also in complex gadgets like computer supplies. This inverter circuit utilizes a modified sine wave design. UPS powe supply features may not be critically required for the operation of sophisticated circuits. This uninterruptibkle power supply presented here can well suffice the requirement. This inverter circuit include Built-in universal battery charger also.
Required Components For the UPS circuit
- IC1= SN74LVC1G132 or a single gate from IC4093
- R4,R5 = 220 Ohms
- T0 = BC557B
Understanding the circuit Design
The IC1 SN74LVC1G132 has a single NAND gate encapsulated in a small package. It is the heart of the oscillator stage and requires just one capacitor and one resistor for the required oscillations. The value of these two passive components determines the frequency of the oscillator and can be changed as u want and this frequency is to around 250 Hz.
The genrated frequency is applied to the next stage consist of a single decade counter IC 4017. The IC 4017 is configured so that its outputs produce and repeat a set of five sequential logic high outputs. in this the input Is a square wave so generated output is also square waves.
Battery Charger Section for UPS
The base leads of two pairs of Darlington paired high gain, hi-power transistors are attached to the IC such that it receives and conducts to the alternate outputs power.
Since the base voltages to the transistors from the IC are skip, the resultant square impulse from the transformer carries only 1/2 the average value compared to the other inverters. This dimensioned RMS average power of the generated square waves very much resembles the average value of the mains AC that is normally available at our home power sockets and thus becomes suitable to most sophisticated electronic gadgets.
this uninterruptible power supply design is fully automatic and will revert to the inverter mode the moment input power fails. This is done through a couple of relays ; RL2 has a dual set of contacts for reversing both the output lines.
Components required for Charger Circuit
- P1=4K7 PRESET, LINEAR
- R6=SEE TEXT
- RL1=12V/400 OHM, SPDT
- RL2=12V/400 OHM, SPDT, D1—D4=1N5408
- C2 = 1uF/25V
- TR1=0-12V, CURRENT 1/10 OF THE BATTERY AH