Saturday, February 11, 2012

How to Make a Mini Homemade Uninterruptible Power Supply (UPS) Circuit

Uninterruptible power supply units are always considered to be having complicated circuitry and are therefore are costly, difficult to procure or build. A simple idea presented here can be built at home using most ordinary components to produce reasonable outputs. It may be used to power not only the usual electrical appliances but also sophisticated gadgets like computers. Its inverter circuit utilizes a modified sine wave design.
An uninterruptible power supply with elaborate features may not be critically required for the operation of even the sophisticated gadgets. A compromised design of an UPS system presented here may well suffice the needs. It also includes a built-in universal smart battery charger.

What’s the difference between an uninterruptible power supply (UPS) and an inverter? Well, broadly speaking both are intended to perform the fundamental function of converting battery voltage to AC which may be used to operate the various electrical gadgets in the absence of our domestic AC power.

However, in most cases an inverter may not be equipped with many automatic functions and safety measures normally associated with an UPS. Moreover, inverters mostly don’t carry a built in battery charger whereas all UPSs have a built in automatic battery charger with them to facilitate instant charging of the concerned battery when mains AC is present and revert the battery power in inverter mode the moment input power fails. Also UPSs are all designed to produce an AC having a sine waveform or at least a modified square wave resembling quite like its sine wave counterpart. This perhaps becomes the most important feature with UPSs.

With so many features in hand, there’s no doubt these amazing devices ought to become expensive and therefore many of us in the middle class category are unable to lay their hands on them.

I have tried to make a UPS design though not comparable with the professional ones but once built, definitely will be able to replace mains failures quite reliably and also since the output is a modified square wave, is suitable for operating all sophisticated electronic gadgets, even computers.

Understanding the circuit diagram

The figure alongside shows a simple modified square inverter design, which is easily understandable, yet incorporates crucial features.

The IC SN74LVC1G132 has a single NAND gate (Schmitt Trigger) encapsulated in a small package. It basically forms the heart of the oscillator stage and requires just a single capacitor and a resistor for the required oscillations. The value of these two passive components determines the frequency of the oscillator. Here it’s dimensioned to around 250 Hz.

The above frequency is applied to the next stage consisting of a single Johnson’s decade counter/divider IC 4017. The IC is configured so that its outputs produce and repeat a set of five sequential logic high outputs. Since the input Is a square wave the outputs are also generated as square waves.




Parts list

R1=20K
R2,R3=1K
R4,R5 = 220 Ohms
C1=0.095Uf
C2,C3,C4=10uF/25V
T0 = BC557B
T1,T2=TIP122
T3,T4=BDY29 or 2N3055 or TIP35
IC1= SN74LVC1G132 or a single gate from IC4093
IC2=4017
IC3=7805
TRANSFORMER=6-0-6V/10AMP/230V
Battery = 12V/25AH


Uninterruptible Power Supply - Battery Charger Section

The base leads of two sets of Darlington paired high gain, hi-power transistors are configured to the IC such that it receives and conducts to the alternate outputs.

The transistors conduct (in tandem) in response to these switching and a corresponding high current alternating potential is pulled through the two halves of the connected transformer windings.

Since the base voltages to the transistors from the IC are skipped alternately, the resultant square impulse from the transformer carries only half the average value compared to the other ordinary inverters. This dimensioned RMS average value 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 and favorable to most sophisticated electronic gadgets.

The present 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 RL1 and RL2; RL2 has a dual set of contacts for reversing both the output lines.

As explained above an UPS should also incorporate a built-in universal smart battery charger which also should be voltage and current controlled.




The next figure which is an integral part of the system shows a smart little automatic battery charger circuit. The circuit is not only voltage controlled but is also includes an over current protection configuration.

Transistor T1 and T2 basically form an accurate voltage sensor and never allows the charging voltage upper limit to exceed the set limit. This limit is fixed by setting the preset P1 appropriately.

Transistor T3 and T4 together keep an “eye” over the rising current intake by the battery and never allows it to reach levels which may be considered dangerous to battery life. In case the current starts drifting beyond the set level, the voltage across R6 crosses over – 0.6 volts, enough to trigger T3, which in turn chokes the base voltage of T4, thus restricting any further rise in the drawn current. The value of R6 may be found using the formula:

R = 0.6 / I, where I is the charging current rate.

Transistor T5 performs the function of a voltage monitor and switches (deactivates) the relays into action, the moment mains AC fails.

Parts list

R1,R2,R3,R4,R7=1K
P1=4K7 PRESET, LINEAR
R6=SEE TEXT
T1,T2,=BC547
T3=8550
T4=TIP32C
T5=8050
RL1=12V/400 OHM, SPDT
RL2=12V/400 OHM, SPDT, D1—D4=1N5408
D5,D6=1N4007
TR1=0-12V, CURRENT 1/10 OF THE BATTERY AH
C1=2200UF/25V
C2 = 1uF/25V

183 comments:

  1. Hi
    What is the watt of above ups?.
    Which battery is suitable for above ups? Pls hlp me

    ReplyDelete
  2. Hi,

    It will depend directly on the wattage of the transformer and the AH of the battery used.

    Suppose if you use a 12-0-12v/20 amp transformer and a 100 AH 12V battery, then the ups would be able to support 300 watts for 3 hours.

    ReplyDelete
  3. how to make a relay circuit is not explained clearily in this homemade UPS..........

    ReplyDelete
    Replies
    1. I'll try to update the article soon, if possible.

      Delete
  4. can u check this ups work properly or not

    ReplyDelete
    Replies
    1. No it's not been checked practically....

      Delete
  5. what is the cost of these two circuits

    ReplyDelete
  6. hi swagatam
    i have to rewound the old computer ups transformer for this circuit. how i calculate how many turns & which guage i can use.old computer ups transformer core area is 32*40 plese suggest me. thanks

    ReplyDelete
    Replies
    1. I am sorry network advise,

      I have no idea regarding transformer designing or winding.

      Delete
  7. hi sir,,,
    sir plz can u tell me or upload, how to make ultra sonic wave mosquito repeller circuit in effectively working condition,etc etc,,

    haris khalil

    ReplyDelete
    Replies
    1. Hi Haris,

      Ultrasonic mosquito repeller are never effective, don't trust these circuits.

      I have already presented one such circuit but the results are doubtful:

      http://homemadecircuitsandschematics.blogspot.in/2012/05/make-this-electronic-mosquito-repeller.html

      Delete
  8. hello sir, hope u will b fine,,,

    i hv some questions in my mind,

    1: can this above circuit be used for 2 household ceilling fans of 220 volts at a time without any sort of modification ?

    2: how can i increase the capacity of above circuit for bear/running required load of my house?

    3: sir, what is the charging current of your above battery charger circuit ?

    4: Is there any formula for calculating charging current for different amperes batteries, OR in other words, how can i find that how many amperes is required for charging batteries of different amps ?

    5: do you have any helpfull artical for understanding relays in above circuit or other various circuits of relays ?

    Waseem

    ReplyDelete
    Replies
    1. Hello Wasim,

      The power of the above inverter can be increased or decreased by simply modifying the transformer and the battery current.

      Roughly, if you multiply the input winding voltage (half winding) with the its current, that would provide you the wattage capacity of the inverter.

      Charging current should be ideally 1/10th of the battery AH, so you can use a transformer with this much current rating.

      You may refer the following article for understanding relays in details:

      http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-understand-and-use-relay-in.html

      Delete
    2. u r good man,,,

      thnx alot


      wasim

      Delete
  9. hello everybody ...
    Do i have to connect the (-ve) pole of the battery to the ground symbol shown in the charger circuit?....help please

    ReplyDelete
    Replies
    1. yes all grounds will connect with batt (-)

      Delete
  10. thanks for the reply swagatam....
    i found that the Average Rectified Forward Current of the bridge diodes 3A (for the charger) is that enough "i think it needs more current i am afraid it is going to melt down, do i have to use another high current diodes like 6A2....

    ReplyDelete
    Replies
    1. Helo Zakaria,

      If you are using a battery that's above 40 AH, then you might require 6A diodes, so it will depend on how much current you want to draw from the charger.

      Delete
  11. This is a very helpful read. I appreciate your time with the knowledge you have provided me with.

    Thanks again!

    Dave

    ReplyDelete
  12. hi, swagatam,
    i tried to run this ckt on multisim , but it wont workd, i replace 4050 by 2sc945, is it ok?
    and plz tell me the range of battery that i can use with this ckt?

    ReplyDelete
    Replies
    1. The transistor is OK, I don't know why it's not responding to multisim.

      Battery should be above 25AH, and rated at 12V.

      Delete
  13. Heloo,
    If i m using 32ah 12 v battry with above given charger circuit what shoud be the value of r6

    ReplyDelete
  14. Hello Swagatam ..I want to make a UPS circuit for load 1600 watt what i have to update in this circuit..

    Thanks

    ReplyDelete
    Replies
    1. hello Alfred,

      you may try out the following circuit for the inverter part:

      http://homemadecircuitsandschematics.blogspot.in/2012/05/make-this-1kva-1000-watts-pure-sine.html

      the above circuit won't give above 100 watts.

      Delete
  15. Hello Swagatam, my project is to make two AC 120 Volt into UPS circuit one from solar energy inverter 120V Sine wave and the other from 120 Volt normal to connect 360 watt and specially computer to don't the data when the energy outage so please help me ..thanks

    ReplyDelete
    Replies
    1. Hi Alfred,

      do you have the 120 V sources available?

      Delete
  16. yes the battery backup 120 v and our Primary Ac 120 vol As well.

    ReplyDelete
    Replies
    1. it means you need a simple relay changeover circuit, please refer to the following article:

      http://homemadecircuitsandschematics.blogspot.in/2012/09/automatic-inverter-supply-and-mains.html

      Delete
  17. Hello Swagatam, Can I have the PCB of these two circuits please and if i want to connect load 30 AMP what I have to change ..thanks

    ReplyDelete
    Replies
    1. Sorry Alfred, I don't have PCB designs for the above circuits.

      for 30 amp load you will have to use a transformer rated at 30 amps.

      Delete
  18. Thanks Swagatam So Much for you help :)

    ReplyDelete
  19. HI swagatam I want made ups of 6v 4.5amp battery and I also want dc output only please reply what is change required.

    ReplyDelete
    Replies
    1. for what application do you want to use it??

      Delete
  20. Hi swagatam I want to build ups from 6v 4.5amp battery and I also want dc output only. Please reply me what is change require in above circuit.

    ReplyDelete
  21. Good job sir let me try to build the ups n inform u later. Vincent

    ReplyDelete
  22. Hi swagatam I am sorry for my late response, I want to build this ups for 1watt 4 LEDs

    ReplyDelete
    Replies
    1. the above UPS is for 220V AC operation, for LEDs you may try the following circuit:

      http://homemadecircuitsandschematics.blogspot.in/2013/03/simple-dc-ups-circuit-for-modemrouter.html

      Delete
  23. Hi swagatam I buy a transistor (2n6107) from a shop in Mumbai and that retailer told me that it was from Motorola company and m8824 code was mentioned on it. When I find Motorola semiconductor manufacturers logo from internet it was different. Please help me how to identify transistor manufacturers logo and other semiconductors. I hope you will reply.

    ReplyDelete
    Replies
    1. A motorola part is not necessary, other brands would also work as good.

      I am not very sure about the initial letters...you may refer to the datasheet of motorola for knowing the exact component codes and equivalents.

      Delete
  24. Thankyou swagatam, ST brand available in Mumbai is ok?

    ReplyDelete
  25. Hi swagatam transistor 2n5294 and only 5294 are same?

    ReplyDelete
    Replies
    1. ST make is good, yes 5294 would be similar to 2N5294

      Delete
  26. Thankyou very much swagatam sir for your reply

    ReplyDelete
  27. hello, I wanna know why its necessary to use 4017? meaning why do we need the sequence to be formed?

    ReplyDelete
    Replies
    1. for triggering the transistors alternately and repeating the processs continuously.

      Delete
  28. can u please explain as to what would be the output of the transistors and what is applied to the transistors?

    ReplyDelete
    Replies
    1. reply please ..

      Delete
    2. everything is explained in the article, please read it.

      Delete
  29. like u hv connected from the primary side a middle point to the ic.. y have u done dat?? would be really helpful if u could reply ... thanks :!!

    ReplyDelete
    Replies
    1. IC3 is a voltage regulator IC for safeguarding the ICs against high voltage surges.

      Delete
    2. dat i get it .... but y have u connected from a point on primary winding is my doubt

      Delete
    3. The battery positive is connected to primary center tap, this battery voltage should also go to IC3 input, so it's connected there.

      Delete
    4. ser.. can i use 12 amps or 6 amps here? for sine wave inverter only?

      Delete
  30. ser what will i replace in T3, and T4 if i dont have BDY29?

    ReplyDelete
  31. ser can i use 6amps transformer here? or 12 amps?

    ReplyDelete
  32. ser what will i replace in SN74LVC1G132 if i dont have it?

    ReplyDelete
    Replies
    1. use 2n3055 for T3,T4

      6 amps will do.

      use ic555 astable oscillator in place of SN74....

      Delete
    2. ser instead of 2n3055 for T3,T4...,can I use 2SD797 here? for inverter only...

      Delete
  33. ser..instead of SN74LVC1G132 that is single 2-input, can i use quad 2 -input..?

    ReplyDelete
    Replies
    1. use a single Schmidt nand gate as found in IC4093

      Delete
    2. ser..thank u so much. if i use 6 amps , how much is the power rating of the inverter ser?:)

      Delete
  34. ser swagatam..i will put a fuse here..is it okay?if i use 6 amps here,,what will be the rating of the fuse? thanks

    ReplyDelete
    Replies
    1. use a 6amp fuse in series with battery positive.

      Delete
    2. okay ser..thank you so much..how about 12 amps transformer here? is that okay ser? for inverter circuit only..

      Delete
    3. 12 amp transformer will also work here.

      Delete
  35. Hello sir ,is that relay? connected point B to point B

    ReplyDelete
  36. pls tell me the range of battery used here?

    ReplyDelete
  37. pls tell me the range of battery used here......

    ReplyDelete
  38. Sir if i am using 60 Ah battery and a 300 W tranaformer what will be the maximum discharge current flowing to the transformer secondary????

    Will it affect the incorporating ICs and components badly if the discharging current goes much high??????

    ReplyDelete
    Replies
    1. discharge rate will depend on how much load you connect at the o/p

      Delete
  39. Can i use TIP 36 instead of TIP35?
    What iz about TIP122?

    In an easy manner is it possible to replace the output driving stage transistors T1 - T4 by two IRF540N mosfets keeping the power output not changed

    ReplyDelete
    Replies
    1. tip36 will not work in the above design.
      single mosfets can be used in place of the two transistors on each channel.

      Delete
  40. SIR I THINK ALL THE PROBLEMS OCCURED TO ME WAS DUE TO THE SERIOUS 'shoot through problem' CAUSED BY ERRANEOUS SIGNAL FEDING OF THE GATES.OF THE MOSFETS( MAY BE AT THE SAME TIME ) that had occured due to the variation of duty cycle of the signal from 50/50. I think my calculations for R & C values in the oscillating stage of 4047 is wrong. I've used R=22.7 K adjusted by a linear 47K pot and C was selected to be 0.1 uf(104) in accordance with the formula f=1/(8.8RC) . But for this i had set f to 50 . So that was the mistake. Wasn't it??????



    Sir let me ask one more doubt to u that even i am getting 50/50 duty cycle with approx. 50 Hz signal, will it undergoe any shoot through again????
    Also can i use a MOVRD240/20 varistor at the secondary terminal in parallel with a 0.1uf/600 V and 2.2 uf/200V capacitors to avoid damage to the appliances from higher voltage

    ReplyDelete
  41. Dear sir, In this schematic which are those components that determines the frequency as well as the duty cycle of the wave. How it can be adjusted?'???

    ReplyDelete
  42. Ram,a 4047 IC will never produce shoot throughs, it's internally protected from this.
    select any standard 4047 circuit from any online source and select the components as per that circuit, instead of calculating it yourself.

    MoV is not necessary in a 4047 circuit.

    ReplyDelete
    Replies
    1. Dear brothef,
      Let me know whether a 0.1 uf can be used instead of a 0.095uf to generate 250 Hz. If it needs accurate precision for generating the more accurate 50 Hz signal how could that capacitor value be implemented using available 0.1 uf or near value capacitors????

      Delete
    2. You can use 0.1uF and tweak the resistor value for getting the exact optimzation

      Delete
  43. Sir which is better for stable working at high output load an IRF540n or IRFZ4????

    ReplyDelete
    Replies
    1. all mosfets are good, they only differ by their voltage and current specs, which must be selected appropriately.

      Delete
  44. Dear sir,
    How can we calculate the maximum power that can be delivered by this circuit given the specifications of battery as well as transformer????'?

    Any formula is there?

    ReplyDelete
    Replies
    1. Dear Alex,
      power will depend on the battery AH rating and the trafo wattage, the IC circuit will remain same for all the variations

      Delete
  45. What is the formula to get 250 Hz at the output of NAND gate IC sir'??
    Can i use CD4011 which is a CMOS IC composing of 4 independent two input NAND gates instead of 4093???? Reply as early as possible Sir...

    ReplyDelete
    Replies
    1. f = 1/0.8RC
      4011 will work but with two or three gates together.
      4093 will allow only a single gate to be used

      Delete
    2. hello, if i use 12v,7ah bettery, then what will the changes occure in above circuits.like transformer rating e.t.c............................................,
      thanks
      ZEESHAN

      Delete
  46. Sir, i am not getting any ac output from this circuit. I have used IC CD4011 ( quad two input NAND GATES) instead of CD4093 also each transistor pairs at output were replaced by IRF540N mosfets .
    0.095uf capacitor was accurately set up by paralling capacitors 0.047uf*2 and 0.001uf(102)

    SIR PLEASE LET ME KNOW HOW TO ENSURE WHETHER IC4017 IS WORKING WITHOUT MEASURING SIGNAL FREQUENCY

    ReplyDelete
    Replies
    1. Ram,you are doing as per your own wish and will,so I cannot suggest you anything.
      you were worried about mosfets getting burnt with 4047 IC circuit so i suggested you to use transistors in your 4047 circuit by referring the above circuit.
      Now you are making the above circuit with mosfets... inviting new problems.
      Stick with your original 4047 circuit and use transistors at its output just as done for the above circuit.

      In the above circuit 4011 will work but with two or three gates together.
      4093 will allow only a single gate to be used

      Delete
  47. SIR, If 4011 is not possible, what about producing scmitt trigger using IC741 opamp???? If it can , how

    ReplyDelete
  48. How the gates can be arranged in 4011. In series????
    I have another doubt also that
    Whether it is necessary to take the center -ve wire when using three batteries in parallel and used as a separate ground????

    ReplyDelete
  49. I Am Very sorry for disturbing you again SIr.
    Actually i was in the middle of searching for a better 200 W to 250W inverter which is suitable to operate even sophisticated components. Atlast i found it in this article. Now i am not so affraid of getting the MOSFETS blown, since it is working properly when i checked the whole in last night producing a favourable ac output. SO I decided to stick on this new project since it can fullfill my needs and used the components as available with me( just changed IC4093 and output stages as said before).. I must must have to implement this to suit my needs. So expect your valuable suggestions for this. Now i want to know , how the gates in 4011 can be used to produce the same result as that of 4093 and make the entire one in working condition

    ReplyDelete
  50. Sir i have connected three NAND GATES in 4011 in series. ( output of first NAND gate connected to one of the inputs of second NAND gate and there inputs shorted. Its output further connected to the shorted input terminals of the 3rd one. Finally 0.095 uf connected b/w the shorted inputs of 1st gate and ground only. Also the 20 k resistance connected in between the first input terminals and the output of the last NAND GATE). When the testing has completed the result was fruitfull. I got ac out. But a small problem is there that i am getting only about 120v out. I could work a 3V adapter for torch with it nut not a table fan. Will you plz help me???

    ReplyDelete
    Replies
    1. OK, if you have succeeded with it then it's a great news.
      since it's a modified sine wave inverter it'll produce 50% less output if the batery/trafo voltages are rated identically.

      for a 12-0-12V trafo you will need a 24V battery for getting 220V with this circuit. you can connect 2nos 12V bats in series for getting 24V.

      Delete
    2. ..but be sure to give 12V only to the ICs.....you can do this by extracting 12V separately from one of the 12V batts.

      Delete
  51. what much maximum power can be drawned from a 24V 20Ah combination SIR????
    Will i get more power by adding an additional 12 V 20Ah battery???? how????

    ReplyDelete
    Replies
    1. around 200 watts..yes more bats can be added for increasing power.

      Delete
  52. Hellow sir........... is this circut features an automatic load correction??? i mean will i get constant 230 V even various loads are used at the load side utilizing differrent loading voltages???
    If it is not, how can it be made to operate such a feature???

    ReplyDelete
    Replies
    1. No this circuit does not have this feature, it will require an external circuit for implementing it...I'll try to discuss it in a new post soon.

      Delete
  53. Sir i want your help again. I think your suggestion at this time is very necessary to complete my work.
    I have done everything as per you suggestions. Put 24V instead of 12 and extract ed separate 12v for ICs from one of the batteries( 12V fed to the ICs after regulation using 7805 ). now i got better ac out which could be understood by a more brighter light indication by TESTER( my voltmeter shows only 23.5 when the range is put in 750V ac. But the led of tester becomes more brighter than the last time at which it was less bright and showed 120V in voltmeter ). But the real problem is , i can't operate a fan 6A rated by this provided all the batteries are fully charged

    ReplyDelete
  54. Will it be an error due to mismatch of value of feedback resistance R1(20k) ???
    Can a pot be used there and adjusted at run time untill fan rotates????

    ReplyDelete
    Replies
    1. yes you can use 100k pot in series with the 20k pot and adjust it for getting 50Hz.

      LED tester is useless for testing an inverter, you should use a 100watt bulb at the output of the transformer.

      check battery power by connecting a car headlight bulb to it...if the bulb lights up very brightly with voltage of the batt not dropping below 12.5v, would confirm a fully charged battery.

      Delete
  55. Hai sir, Ram again.
    As per your suggestion i used 24 V battery bank for the purpose of 230V generation. Now i need a charger suitable for the battery. SO i have created a logic turn over switch for the battery bank which allows the batteries to connect in series when power is needed during power failure and connect in parallel when charging mode is reached. I have drawn a simple schematics to make it practical using only a rated relay. I have posted the diagram in the link given below. Please study it and point out mistakes if any sir.

    http://postimg.org/image/6zzajm78j

    May i ask you onething that ,can the 24V battery be charged with a 15-0-15 transformer by extracting 30V from the terminal leads????

    i have made such a schematic intented to modify for parallel charging of higher rated batteries which are usually connected in serious under load...n

    ReplyDelete
  56. Sir, the image i posted before is little blurred. Here is a better version. Plz check it ou

    http://postimg.org/image/s6j9wxexh/

    ReplyDelete
    Replies
    1. Hi Ram,
      It looks correct to me, however will need practical verification for confirmation.

      yes 30V from 15-0-15 can be used for charging a 24V baterry

      Delete
  57. Sir in one of the comments in this article, i saw the formula for getting 250 Hz signal by the schmitt trigger arrangement as f= 1/0.8RC.
    How it is possible for 'f' to hold a value of 250 by chosing R as 20k and C as 0.095uf. Is it a calculation mistake????
    I am getting 658 as the value for 'f' on substituting these

    ReplyDelete
    Replies
    1. 20k is not the correct value.
      and C will be in farads not in uF, so you should first convert uF into F before substituting the values in the formula.

      Delete
  58. Sir what are the values of frequencies coming from pin2 and pin7 of IC4017 in this figure??? Can i use these values to make an assumption to ensure that the exact 50Hz ac is coming out of transformer primary????

    ReplyDelete
    Replies
    1. Superman, it should be 50Hz on either pins, yes surely if this is confirmed, the output from the trafo would be also confirmed with the same.

      Delete
  59. Sir,
    Can you please suggest a PWM based inverter circuit that uses the PWM chip ic SG3524 as the heart of entire operation ??
    The output of the inverter shouldn't be fluctuated with varying loads and the inverter should be capable of operating atleast a 250 W load.
    One of the most necessary requirement that i missed to say is that, this inverter should be capable of driving even sophisticated components such as laptops

    ReplyDelete
    Replies
    1. Arun, you can try the following circuit, it can be used for operating laptops also:

      http://homemadecircuitsandschematics.blogspot.in/2013/01/modified-sine-wave-inverter-circuit.html

      Delete
  60. sir, are the two circuits above working? are they well-tested?

    ReplyDelete
  61. can i use 6amps instead of 10amps transformer? will it affect the circuit?

    ReplyDelete
    Replies
    1. great! thanks! but what appliances this ups can possibly drive if i use 6amps transformer?

      Delete
    2. appliances such as lights fans below 60 watts can be operated with a 6amp trafo

      Delete
    3. thank you Swagatam for that info. I just have few more questions about this project:
      1. what is the replacement for SN74LVC1G132?
      2. did you simulate the circuit on breadboard or in proteus?
      3. what is the power rating of the resistors?
      4. do you have a pcb layout on this?
      5. is this project uses pulse width modulation?

      Delete
    4. 1)you can use a single nand gate from the IC 4093 or a 555 IC astable will also work.
      2)I simulated it in my mind not with any any software.
      3)all resistors are 1/4 watt except R6
      4) it's a crude modified sine wave, but does not incorporate a pwm circuit.

      Delete
    5. thank you sir! do you have any simple circuit that uses digital communication?

      Delete
    6. sorry, presently i do not have this circuit.

      Delete
    7. it's ok sir.
      if i use 6 amp transformer, how may hours can it operate an appliance below 60 watts?

      Delete
    8. the backup time will depend on the battery AH rating, higher value will produce higher backups and vice versa..... it has no connection with transformer ampere rating.

      Delete
    9. thank you sir! can an IC be added in the above circuit to save standby power? and what IC should be used?

      Delete
    10. no that cannot be done, simply disconnect the battery and it will stop the circuit from any consumption.

      Delete
  62. Hey...your design is great.I wanted to know how you calculated the capacitor and resistor values to get a frequency of 250Hz.and how can i change the values to get a 50Hz frequency?

    ReplyDelete
    Replies
    1. Thanks Robe,
      Actually it has to be 250Hz at pin14 of the IC for achieving 50Hz across the transistor bases, since the sequencing of the output pins of 4017 are not continuous rather skipped in between for getting the proposed modified output.

      Delete
  63. Sir,
    How much power will i get from my 24 V 40 Ah battery bank and a 230/11.5-0-11.5V power transformer ?????

    Battery bank formed by the series combination of two 12 V 40 Ah battery banks, each 12V 40 Ah battery bank is a parallel configuration of two 12V 20 Ah sealed lead accid batteries, means i have formed a 24 V 40 Ah battery bank with suitable configurations of four 12V 20 Ah batteries.
    Transformer has 5 input windings and 4 output windings. The maximum voltage at secondary terminal is 15 V

    ReplyDelete
    Replies
    1. You can easily obtain 250 watts from 24V/40ah provided the trafo is also rated at around 300 watts.....

      Delete
  64. Sir can you please suggest a method by which the ouput voltage of the above circuit willn't further deviate with varying loads ????

    ReplyDelete
    Replies
    1. Arun, you can try incorporating the following circuit with the above circuit:

      http://homemadecircuitsandschematics.blogspot.in/2014/01/automatic-output-voltage-regulator.html

      Delete
  65. sir, is there any replacement for bc547 BC557B, 1n5408, TIP122 and TIP32C?

    ReplyDelete
    Replies
    1. TIP122 does not have an easy alternative....for the rest can be found in the link I provided you in your other comment

      Delete
  66. sir im confused about relay 2? the contact in point b and c are in NC only?

    ReplyDelete
    Replies
    1. RL2 is a DPDT relay which has two sets of contacts inside one package.

      Delete
  67. oh i see..so its DPDT in relay 2..can i use another relay and put at relay 2 parallel in the circuit ?..because i can't find in my place a DPDT relay.

    ReplyDelete
    Replies
    1. yes, that's correct, and you can surely use two SPDT relays and join their coils in parallel for getting the same results.

      Delete
  68. sir is there any replacement or alternative that i gave in the above comment, the electronic components?because i have same problem in DPDT relay..i really appreciate all your works and very nice masterpiece..thank you for this.

    ReplyDelete
    Replies
    1. Please refer to the link which I gave in your other comment....it consists of the list of the all the equivalents...

      TIP122 has no direct replacement

      Delete
  69. sir, i need you help..i made the ckt. above..and im having a problem in the circuit in the UPS..in the the inverter ckt. the output voltage in the transformer is only 150v instead of 230v..why?..please help me sir

    ReplyDelete
    Replies
    1. Erns, please use a 9-0-9v or a 6-0-6V trafo, this will solve the issue

      Delete
  70. hi sir we have to make a 100watt ups. so sir in second circuit the value of resistance R6 is in ohm or kiloohm.

    ReplyDelete
    Replies
    1. Hello sir
      In ups 100watt bulb does not glow when main switch is off.Any solutions for this...Sir
      When main switxh is off outputvoltage is reduce...

      Delete
    2. you should first make the inverter section separately and confirm the results and then integrate with the changeover relays.

      Delete
  71. Sir what is the rating of battery and step up transformer .we have to make 100 watt ups....

    ReplyDelete
    Replies
    1. 9-0-9V/10amp/220V is the transformer rating
      the battery could be a 12V 25AH lead acid battery.

      Delete
    2. transformer should be a 6-0-6v/10amp..it's clearly mentioned in the parts list

      Delete
  72. Sir what is the output of this ups circuit?????????

    ReplyDelete
  73. Hi mr.Swagatam,
    I am Jayasuriya from Sri Lanka.While appriciating your valued replies,Kindly explain how to measure power output(wattage) of a locally made power inverter

    ReplyDelete
    Replies
    1. Hi Hapu,
      thanks!
      the easiest way to test it is by loading the output of the inverter gradually until the voltage begins dropping. The total value of the load wattage during that instant will provide the wattage capacity of the inverter.

      Delete
  74. Sir, it z very interesting to implement your ideas.... Thank you so much sir for providing us such various ideas.
    Now i am in the middle of making a small 150 W UPS system .... I have a 15 V 5A Old Thoshiba laptop charger, four no.s of 12 V 20Ah sealed lead accid batteries taken from an old electric scooter, and some necessary components to make out the UPS......
    The main intention behind this is : i want to charge my mobile phone, laptop, even a torch during power failure.. The inverter should also support a table fan....so a maximum rating of 150 W is necessary....
    Since i want to operate such sophisticated components , could u plz suggest me the most appropriate version satisfying all ma needs..n
    Also i want to know that, if the UPS is based on PWM, what battery voltage to be selected...12 or 24 ??...
    I have only a 15 V charger with me... So if i have to use 24 V confih. (series combination of two parallel configuurations each 12V 20 Ah batteriea = 24 V 40 Ah ), how it be possible to break all these config. and forming a complete parallel config. ( 12 V 60 Ah ) for charging7 ????

    ReplyDelete
    Replies
    1. Thanks Arun!
      Here fan is the only gadget that will require 220V rest of the items (cell phone, laptop, torch) can be actually charged directly from the battery, so an inverter won't be necessary for those items.
      anyway if you want to charge them from the same inverter you may do so and it won't be necessary to employ a sine wave inverter since all these items work on DC and any AC whatsoever will be ultimately converted to DC, so even a square wave inverter would work for the application.

      you can try the desin that's shown in the above article or you can try the one that's shown in the following link

      http://homemadecircuitsandschematics.blogspot.in/2012/09/mini-50-watt-mosfet-inverter-circuit.html

      both can handle upto 200 watts

      for charging a 12V 20ah battery you would require a 14V/3amp battery, so your smps will need to be 14V at least, 12V will not work.

      Delete
  75. Sir what much wattage to be expected by two 12V 20Ah batteries in series ?.... The Transformer is rated at 12V,300W

    sir i failed in executing the below design for my need

    http://homemadecircuitsandschematics.blogspot.in/2012/09/make-400-watt-mosfet-sine-wave-inverter.html#comment-form

    Again i have decided to go on with the current UPS design.... Now as a whole saying i got AC out.... But a 100 W bulb didn't give a single glow on connecting it at the output of the transformer... On measuring the amount of current passing to the centre secondary winding of the inverter transformer , i came to know that only 0.77A current is flowing, thereby it seemed to produce a power of only 18.48 W ( 24.5 * 0.77 ) at the output.. That is why the bulb didn't glow...

    SO Tell me sir, how the amount of current ( that to be drawn from the battery ) could be increased to a minimum level of 7A, so that inverter output reaches a minimum of 175W....

    NOTE:::: SIR, I HAVE TESTED THE BATTERIES USING A CAR HEADLIGHT LAMP ( 12V, 60 W )....... THE AMMETER SHOWED A READING OF ABOUT 5A AT FULLY CHARGED CONDITION OF THE BATTERY.
    I have used 2 no.s of 20Ah batteries in series......
    Eventhough the expected wattage couldn't be achieved by this config., the current drawn from the 40 Ah config ( Series config. of two battery banks, each banks are the parallel config. of separate batteries ) was also seen to be so low, so that the 100 W bulb couldn't start glowing...


    YOUR HELP IS THE ONE AND ONLY EXPECTED SOLUTION AT THIS POINT

    ReplyDelete
    Replies
    1. Arun, What is the rating of the transformer that you have used? If it's a 5amp transformer it should weigh about 4 to 5kgs, if it's much lighter than this would indicate a lower rated transformer which won't produce the intended results.

      the voltage rating of the trafo must be lower than the battery voltage, for 24V it must be 18-0-18V

      check the gate voltages, the peak voltage should be 12V since it's supply is 12V and the average voltage should be 6V since it's operating at 50% duty cycle.

      please check all this and correct them accordingly.

      Delete
    2. 12-0-12V will also do, 300watt must weight at least 12kgs.

      initially keep the PWM diodes disconnected and check the results.

      Delete
  76. Sir, another doubt too

    Can i really use sophisticated equipments such as laptops, mobile phone chager etc. with this UPS circuit ??

    ReplyDelete
    Replies
    1. yes, it will support all those gadgets.

      Delete
  77. i CAN'T SEE ANY PWM DIODES IN THIS CIRCUIT SIR.......
    i have send you mail... could you plz check it SIR

    ReplyDelete
    Replies
    1. I was referring to the previous 400 watt design, I was trying to troubleshoot that circuit.

      Delete
  78. Sir,
    Will the voltage be stable at the output...
    I mean,, will there be any problem in connecting more than one instruments at the output.
    I want to connect maximum of 4 instruments ( A Notebook charger of 13.5 W, A mobile charger of 5W, A Table fan of 80 W, )
    Will they get burned ???

    And if this connection is not possible, how to make the AC Voltage stable independent of different loads in this circuit???

    ReplyDelete
    Replies
    1. Arun according to me there won't be any problem with the mentioned gadgets since all these employ SMPS regulated power supplies except the fan which is not so vulnerable anyway..

      To make things stable the PWM feature is essential.

      By the way how did you proceed with the above circuit, what components did you use?

      Please send me the built units picture for reference.

      Delete
  79. I have also an another doubt sir...

    1). What is the main difference between a normal MOSFET inverter and an H bridge MOSFET Inverte ?

    2). Will the former one have more efficiency than the other

    3). Does the H bridge means the config. in which 4 MOSFETS are used with each pair of mosfets connected in parallel ??

    ReplyDelete
    Replies
    1. H bridge will require a transformer with no center tap which allows the use of smaller trafos and thus efficiency increases.

      H-bridge can be made using sophisticated driver ICs which are specifically designed for such applications thus faults could be rare with this topology.

      you may refer to one good design here:

      http://easy-electronic-circuits.blogspot.in/2014/05/100-watt-to-1000-watt-pure-sinewave.html

      Delete
  80. Sir,
    First of all let me say thanks for all the valuable supports and suggestions that were made from your side in doing the current UPS design....
    Now i want to know few things about thz...;

    1). What will be the value of frequency shown at the gate terminals of the MOSFETs if the output stage is gonna completed using MOSFETs ? Will this be the same 50 Hz that is really expected to be, or more than that ( say few Khz, 666 Hz ) ?

    2). How does the developed ac resembles to the real AC, helpful to be used for sophisticated components ??


    ReplyDelete
    Replies
    1. Thanks Arun,

      1)gate frequencies must be around 50Hz.

      2)In the above design, the output will not resemble a real AC, you can modify it digitally for the same by employing a PWM input

      Delete
  81. Sir,
    Could you plz tell me how to measure an ac current using an ordinary digital multimeter ???
    I have never faced such a situation of measuring the ac current, was only concentrated in measuring dc current... so at the first, trying to measure connecting the +ve lead of the meter to ac live and the negative lead to one of the plug lead of a table fan, keeping the neutral connected as usual gave a result which tends to have an up and down values 1.7 and -0.5 something at the 200 mA range of the meter

    ReplyDelete
    Replies
    1. Arun,
      select AC range in your digital meter (220V) and simply touch the prods across the source terminals, don't bother about the polarity since AC has an alternating polarity and can be checked anyway round.

      But please remember that in your inverter AC will be available at the output of the trafo only.

      At the gates of the mosfets it will pulsed DC, not AC, so here you will need to use the DC range for the measurements.

      Delete
  82. Sir,
    I asked you to how to measure AC current, not the voltage...
    I want to find the power consumption of the TV when it is switched on by P= V*I

    ReplyDelete
    Replies
    1. sorry, current can be measured by putting the meter prods in series with any one of the load wires.
      Select AC range and 10Amp range in your meter....in some meters it's 10amps in some it could be 20amp, both will work.

      Delete
  83. Also tell me whether it is possible to replace the 8550 transistor in the battery charger section by another pnp transistor such as BC557 and 8050 by BC547 ??????

    ReplyDelete
    Replies
    1. Arun, 2N2907 could be used but the above battery charger circuit could be difficult to set and monitor for you, I would recommend a tested circuit using an opamp as given in the following link (see second diagram).

      http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-make-simple-low-battery-voltage.html

      Delete

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