Simple UPS

john January 17, 2011 63 Comments

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.
Comments
  • RAVALI AND THE FRIENDS
    September 1, 2015

    explain circuit components f1 & f2

  • Akhmal
    July 4, 2015

    sir, can i know type of transformer?

  • neha
    June 2, 2015

    what happens when an ammeter is connected across the circuit????

  • December 8, 2014

    It’s mentioned here to use a 12V transformer. How can you charge a 12V battery with a 12V source. On top of that there is diode D3 which will again drop the voltage by 0.6V which leaves us with 11.4V right?

  • cres
    October 30, 2014

    Hi all,

    I am wondering what type of diode is D5,3,4?

  • cres
    October 30, 2014

    HELLo I am wondering of what is really the compon F1 AND F2? is that a fuse??

  • Joe
    October 13, 2014

    Hi. I would like to know if I the circuit allow a 6 volts/1 Ah SLA battery. Should I have to change R1 and Diodes? How could I add a cut off over charge feature and low battery indicator led?

    Regards.

  • zahra
    May 23, 2014

    what’s the difference between regulated and unregulated voltage ?
    plz explain the function of IC in thz circuit

    • Seetharaman
      June 27, 2014

      Unregulated voltage is the one which will be higher when no load is connected and reduce as the connected load draws higher current. With the varying load demand if the voltage is constant it is called the regulated voltage. The unregulated 12 volt DC is stepped down to 5 volts regulated voltage by the IC.

  • max
    May 7, 2014

    With 12vdc 10ah on this circuit, how long will it last if I use a device running on 5vdc 700ma

    Forgive me that I don’t have electronic background. Hope you can understand my English too

    • Seetharaman
      May 9, 2014

      The load on the battery is 700mA (whether the load is on 12 volt or 5 volt) the capacity of the battery is 10AH @ C20 rating. 10000 / 700 = 14 hrs approx. Since the discharge duration is less than 20 hrs, derate the capacity by 10% That is the fully charged battery can give an operation duration of 12 1/2 hrs.

  • maher waheed ahmad
    April 1, 2014

    sir how this circuit invert 12 v in to 230 v ?

    • Seetharaman
      April 2, 2014

      Hi this is a circuit supply 12 and 5 volt dc from 230 volt AC. in the event 230 ac fails the inbuilt battery will supply 12 and 5 volt dc supply to the load.

  • maher waheed ahmad
    April 1, 2014

    up ur knowledge

  • fabio
    February 27, 2014

    hi sir
    which kind of battery can connect?

    • Seetharaman
      March 3, 2014

      SLA battery 12volt 7 to 10 AH rating

      • aijaz
        June 26, 2014

        how can we calculate the time how long the battery will back up to the load.i.e if the battery is of 88ah then what s the time of back up will be ,,,,

        Thanks

  • T.ASAITHAMBI
    January 28, 2014

    Sir,can i use 12-0-12 center tapped transformer instead of 12-0 for simple ups system

    • Seetharaman
      January 31, 2014

      Hi Asaithambi You can use in full wave rectifier form with only two rectifiers instead of bridge rectifier with 4 rectifiers. you please to following web site
      http://en.wikipedia.org/wiki/Center_tap

  • husni
    January 24, 2014

    I think 5v and 12v out is in dc,and only dc load can be connected.hw it can be connected to a ac load.

  • rajib ranjan
    January 4, 2014

    how does work transistor?

  • ganpat
    September 8, 2013

    sir i need the rating for batterty use for above simple ups and which type of load are connected to this ups.and provide complet working of this ups .

  • June 21, 2013

    this circuit cannot charge 12 volt battery. in operation the battery dicharges continuosly when the circuit is connected to the main power source.

    • Subrata Mahata
      January 7, 2014

      I think you connected battery terminals oppositely. So connect battery terminals properly.

  • cooool
    June 4, 2013

    Hi sir what change is required for 6v 8.5amp battery?

    • Subrata Mahata
      January 7, 2014

      Connect two 6V battery in series.

  • cooool
    May 19, 2013

    Sir what is change required for 6v 4.5amp battery.please reply me

  • cooool
    May 18, 2013

    seetharaman sir what is change required for 6v 4.5amp battery

  • cooool
    May 17, 2013

    Sir what change is required for 6v 4.5 amp battery

  • cooool
    May 13, 2013

    Thankyou seseetharaman sir.

  • cooool
    May 11, 2013

    Hi seetharaman thankyou for reply. what is the suitable transformer for the battery 6v 4.5amp and 6v 8.5amp connected in series.

    • Seetharaman
      May 12, 2013

      Hi coool you cannot connect two batteries of different AH rating in series for while charging them, they will loose their operating life expectancy as their charge characteristics are different.

  • cooool
    May 10, 2013

    Sir this circuit has facility of over charge protection? Please reply me

    • Seetharaman
      May 11, 2013

      Hi cooool the transformer is suitably chosen to take care of it. the max charge current is taken care by R1.

  • April 30, 2013

    sir, please i need more explanation to build this circuit sir,
    i want to know how the inverter change the 12v to the 220v cos i can not see the step up transformer in the circuit and more so the inverter circuit is not clear to me.

  • April 11, 2013

    Hello.
    I’ve made the circuit., But the output voltage is 16 volts, why?

    Urgent Please…

  • March 11, 2013

    sir I want simple ups circuit diagram please replay me

  • arun prasanth.k
    January 15, 2013

    for what purpose the resistance R1 (220ohms) used in this circuit?
    pls reply sir..urgent we are moving with this mini project….

  • September 28, 2012

    can we use this ups circuit to power the computers……. what is unregulated 12 v supply please reply me soon

  • divya
    September 17, 2012

    the circuit is super.it is so easy to understand.thankyou.

  • Andrew
    August 11, 2012

    ok, this circuit will charge the battery?

  • May 14, 2012

    Thanks

  • sohail
    April 5, 2012

    plz sir reply me through email address

  • sohail
    April 5, 2012

    sir i want to see the battery bank circuitry inside the ups and how we can estimate the ups health and this is possible to estimate batteries health individually or we can estimate the health of the banks as a whole.

  • January 7, 2012

    Dear all

    we are looking 96/120V on line ups charger

  • Ganesh R
    November 27, 2011

    Respected sir,
    thanks for quick reply.. I need a circuit of 16v unregulated and 12v regulated with atleast 1.2A as output.. I’m planning to use 16-0 3A step down transformer.. So i’m planning to use 7812 IC instead of 7805 ic inside the circuit to get 12v 1.2A as the output.. My questions are
    1) Will the ic 7812 work fine and give 12v and 1.2A as o/p?
    2) wat resistor should i use to charge the battery, 4.4 ohm 10w or more?Is there any over charge protection step for the battery?
    3) And is 3A transformer enough for charging battery and to power my dlink internet modem of 1.2A at the “same time”?
    4)Also i want to add a battery over charging protector circuit as in http://www.circuitstoday.com/automatic-led-emergency-light . its for 6v battery. i want to use it for my 12v battery with 16v transformer o/p.. just tell me what all to be changed..

    Plz kindly answer all the 4 questions.. Plz sir, i’m in very confused situation.. I know i’m torturing you, even though i’m thanking you for your valuable support.. Thanks will u plz reply via email ganeshrnet{@}live{.}com

    • Mwesigwa
      January 20, 2013

      Hi sir ineed help 4 acircuit diagram of an inverter of 3kva us an ic (cd404s)& Qs(irfp 064n)

  • Ganesh R
    November 27, 2011

    Respected sir,
    thanks for quick reply.. I need a circuit of 16v unregulated and 12v regulated with atleast 1.2A as output.. I’m planning to use 16-0 3A step down transformer.. So i’m planning to use 7812 IC instead of 7805 ic inside the circuit to get 12v 1.2A as the output.. My questions are
    1) Will the ic 7812 work fine and give 12v and 1.2A as o/p?
    2) wat resistor should i use to charge the battery, 4.4 ohm 10w or more?Is there any over charge protection step for the battery?
    3) And is 3A transformer enough for charging battery and to power my dlink internet modem of 1.2A at the “same time”?
    Plz plz plz kindly answer all the 3 questions.. Plz sir, i’m in very confused situation.. Thanks will u plz reply via email ganeshrnet{@}live{.}com

  • seetharaman
    November 26, 2011

    Hi Ganesh R1 should be 2.2 ohms 10 watts wire wound resistance. If you donot include the battery may get damaged over a period of time.

  • Ganesh R
    November 25, 2011

    Sir, i wish to know whether the removal of R1 which is 220ohms for better charging of the 12v battery? I think the battery when connected in serial with a resistor will reduce the charging efficiency? So if we can remove and adjust the resistor, it will be better no? Is there any problem in that? Will it affect auto charging or will it reduce the output voltage to the unregulated 12v lead, while in power mode condition? And also I’ve designed my own circuit diagram removing R1 220ohm.. the link to the described diagram is : http://i43.tinypic.com/flx106.jpg please see it and reply via email ganeshrnet{@}live[.]com

  • seetharaman
    November 1, 2011

    Hi Sooraj if you are using 12volt 7AH battery and if you load is around 1.5amp both 12 and 5 volt put together then it will work for 4hrs during a power breakdown.

  • November 1, 2011

    plz tell me about its backup time and price for creating one. i mean overall price including the battery..

  • seetharaman
    August 7, 2011

    Hi Abdullah what are your plans with this circuit. what is your application.

  • abdullah
    August 6, 2011

    Can we increase batteries in this circuits…….!

  • June 6, 2011

    what about cost and output supply

  • Seetharaman
    March 16, 2011

    Hi Electrominds the transformer itself is rated for 12 volts hence with the pk voltage of 16.8 volt in series with R1 220 ohms, the drop across D3 and power consumed by LED, put together will not over charge the battery will only trickle.
    to charge drained battery the resistance R1 has to be reduced to 6.8 ohms 10watt. with fully charged battery 0f 7AH 100mA will be trickling the battery.

  • electrominds
    March 15, 2011

    is there any overcharging protection in the circuit

  • max
    November 9, 2010

    hi, can i have the component list for this circuit

  • seetharaman
    April 23, 2010

    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

  • EDGARDO DIOLOLA
    April 23, 2010

    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.

  • December 20, 2009

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

  • Solomon Igwe
    May 9, 2009

    I need an overload protector circuit for an inverter circuit of 3KVA

    • Antony
      December 25, 2013

      How do we connect ground

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