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uninterruptible Power supply

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Gregory Okello

Newbie level 3
Aug 10, 2009
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uninterruptible power supply schematic

Hi guyz
Am working on a ups project and am very much in need of a simple schematic circuit and may be the design. Specifications include ac input and output of 240v-ac and it be an online type.


uninterrupt power supply presentation

check this don't know if it is enough for your application but I have used it once.
**broken link removed**

irf540 power 12v power supplies


Checked the site given by pakitos but still couldnt get the circuit i needed for the ups.Pliz any one who knows a simple UPS circuit to assit. You can post it through my email- Its urgent


cd4047 ic spcification

Hi Kripton

Am very thankfull for the circuit that you send me, it can be of great help in my project. I have a problem on how it works and how to come with values of the components in designing it. I would appreciate any efforts towards these.Anyone who can assisst,please help Kripton in assissting me.

God bless,thanx

uninterruptible power supply basic schematic

Mr Gregory, the project I sent also has some info were you able to read it? Well it is from the EFY magazine whose circuits are tested and I used it also once here is the info if you still need help just specift in details
UPS For Cordless Telephones
Cordless telephones are very popular nowadays. But they have a major drawback, i.e. they cannot be operated during power failure. Therefore usually another ordinary telephone is connected in parallel to the cordless telephone. This results in lack of secrecy. UPS is a permanent solution to this problem. Since the UPS is meant only for the cordless telephone, its output power is limited to around 1.5W. This is sufficient to operate most cordless telephones, as these employ only small capacity adapters (usually 9V/12V, 500mA), to enable the operation of the circuit and to charge the battery present in the handset. The UPS presently designed is of on-line type. Here the inverter is ‘on’ throughout, irrespective of the presence of the AC mains. When the AC mains is present, the same is converted into DC and fed to the inverter. A part of the mains rectified output is used to charge the battery. When the mains power fails, the DC supply to the inverter is from the battery and from this is obtained AC at the inverter output. This is shown in Fig. 1. The circuit wired around IC CD4047 is an astable multivibrator operating at a frequency of 50 Hz. The Q and Q outputs of this multivibrator directly drive power MOSFETs IRF540. The configuration used is push-pull type. The inverter output is filtered and the spikes are reduced using MOV (metal oxide varistor). The inverter transformer used is an ordinary 9-0-9, 1.5A mains transformer readily available in the market. Two LEDs (D6 and D7) indicate the presence of mains/battery. The mains supply (when present) is stepped down, rectified and filtered using diodes D1 through D4 and capacitor C1. A part of this supply is also used to charge the battery. In place of a single 12V, 4Ah battery, one may use two 6V, 4Ah batteries (SUNCA or any other suitable brand). The circuit can be easily assembled on a general-purpose PCB and placed inside a metal box. The two transformers may be mounted on the chassis of the box. Also, the two batteries can be mounted in the box using supporting clamps. The front and back panel designs are shown in the Fig. 3. The same circuit can deliver up to 100W, provided the inverter transformer and charging transformer are replaced with higher current rating transformers, so that the system can be used for some other applications as well.
By the way here we thank by pushing helped me and not saying thanks

uninterruptible power supply simple schematic

Hi Pakitos

Am greatefull for the assistance you are offering. I got the information you send but could only help me understand the circuit operation.To be specific, am really intrested to no how to get the values used in the components,how the signals produced by the IC1 CD4047 operates the inverter section and the switch. Generally all these entails the design.I find it difficult to explain my choice for the components values unless have some working on how they come.

Please assist if got knowledge on this.


this is over kill if the man wants to build a invertor thats great but lets not bs.
look if you are going to build a invertor do this correctly and not waste your invertor on silly things like phones if you need a device output for a phone make special outputs on the invertor for them that offer 9 or 12 volt out yes most phones are 1amp MAX things like modems are routers the most i seen was 2 amps so in short you have your invertor for 240volt 50hz use that for devices that are near impossible to run off the batt such as TV or dvd player ect. things like modems , portable phones, routers, ( 5 to 12volt range ) make outputs for them using dc to dc convertor circuits add that on to your invertor thus putting less LOAD ( Stress ) on your invertor and let it run the devices that really need 240volts.

contact me if you need help or just right to my invertor design room.

Added after 4 minutes:

the other thing is if you want true UPS that has no second delay get your self a old welding Transformer add some diodes high AMP that will be enough to charge your batts and run your invertor most Welding Transfomers i have seen have a secondary winding of 14.4volts AC @ 200amps always check this before you try it just check with a multimeter ( clamp meter is better for high current )

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