Simple UPS

Description.

This is the circuit diagram of a simple UPS that can deliver 12V unregulated and 5V regulated DC. The transformer T1 steps down the mains voltage to 12V AC and then the bridge B1 rectifies it. The rectified signal is smoothed by the capacitor C1.When the mains supply is available the battery will be charged via diode D3 and the regulator IC gets supply via diode D5. 12V and 5V DC will be available at the output terminals. When mains supply is not available the battery supplies current to the regulator IC and to the 12V DC terminal through diode D4.Also, the diode D3 blocks reverse flow of current during battery mode. Capacitors C2 and C3 acts as filters.

Circuit diagram with Parts list.

simple-ups-circuit

Notes.

  • Assemble the circuit on a good quality PCB.
  • The transformer T1 can be a 230V AC primary, 12V secondary,3A step-down transformer.
  • The bridge B1 can be a 2A bridge. If such a bridge is not available, make one using four 1N4007 diodes.
  • The capacitor C1 must be rated at least 25V.

3 Responses to “Simple UPS”

  1. Niranjan k.c says:

    It is very very good website I like it and you also visit my site and give me some ideas for it betterments.

  2. EDGARDO DIOLOLA says:

    This a good circuit.
    Can I have a circuit diagram same as this having voltage output of still 5V, but the other output is 19VDC, of course, the battery will be 24 Vdc.I just do not know how to design a circuit to have an output of 19VDC, 5VDC.
    More power to you.

  3. seetharaman says:

    Hi Edgardo You use 24 volt battery increase transformer rating to 24volt 2Amp secondary rating. use a standard adjustable regulator before F2 for whatever voltage you want. you may use one of the regulator circuit published in Circuits today. If your current requirement is within 1amp you can use LM317T ic voltage regulator. you can refer to manufacturers data sheet
    http://www.national.com/ds/LM/LM117.pdf

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