# how to convert dc voltage into higher dc voltage using transformer????

by tefavolc
Tags: convert, transformer, voltage
 P: 29 i am tring to convert 9 volt dc into 120 volt dc , and i ve to use transformer ,,, the problem is the transformer must have input ac voltage as it work on flux variation . i think the solution is to convert the input dc into ac and then use bridge rectifer at the output to convert it agine into dc ,, but how can i convert the input dc into ac ???????
 P: 22
 P: 241 You can use boost converter to step up DC. Basic information can be found in wikipedia page http://en.wikipedia.org/wiki/Boost_converter
P: 29

## how to convert dc voltage into higher dc voltage using transformer????

 Quote by n.karthick You can use boost converter to step up DC. Basic information can be found in wikipedia page http://en.wikipedia.org/wiki/Boost_converter
is there an electronic devise for the boost converter ,,, or i ve to construct the circuit my self??
 P: 50 What power requirement do you need? What power is available with 9v source?
P: 29
 Quote by Quantum-lept What power requirement do you need? What power is available with 9v source?
sry ,,but how can i know that ??
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P: 11,911
 Quote by Quantum-lept What power requirement do you need? What power is available with 9v source?
 Quote by tefavolc sry ,,but how can i know that ??
Another way of asking the question: what are you using for a 9V source? What will be connected to the 120V source?

Also, you'll need to know either the current or the power for both the 9V source and whatever is connected to the 120V source. These should be specified somewhere.

 P: 29 i think i find a simple way here http://en.wikipedia.org/wiki/Power_inverter
 P: 422 A transformer works on the principle that the magnetic field is induced by the derivative of the flux. Basically, you need the alternating voltage for the device to work while dc voltage does not do this.
 P: 29 i ve reached a devise that convert the dc into ac ,,it depend on the unstable of transistor as beta changes so ic and ib changes making flux variation in the transformer coils(12v\220v) and produce ac voltage in the other terminal,,,, but the problem is when i measure Vout with R1=infinty it give value of 150 volt and when i change the value of R1 the voltage change with it directly .. how can i make the voltage constant what ever resistance i put?????? shokrn mokdamn (thnx in advance) :D Attached Thumbnails
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P: 11,911
 Quote by tefavolc .. how can i make the voltage constant what ever resistance i put??????
You can't.

If you think you can, you shouldn't be working on 120V circuits. Instead, learn about electronics with lower voltage circuits first. It's a simple matter of your own safety.
P: 29
 Quote by Redbelly98 You can't.
why??!!would u plz explain
 PF Patron P: 322 Using an isolated Flyback converter (or two) you could satisfy the constraints of "increasing a dc voltage by 'using' a transformer".
P: 3
 .. how can i make the voltage constant what ever resistance i put??????

You'll have to increase the power capability of your DC source on the primary so that it can handle the load on the secondary.

Power is finite in this circuit. Let's say that your DC source can supply 100mW of power, and for simplicity, we'll assume a lossless transformer

P = V * I -> P/V = I

0.1 / 150 = 667 uA

So if your DC source can supply 100mW of power, the most current you could draw on your secondary would be 667 micro-amps to sustain 150V

V = I * R -> R = V/I

150 / 667^-6 = 224887 ~ 224k

So your biggest load would have to be equal to or greater than 224k. If you increased the load beyond that (lowered the resistance so that current increased), your voltage level would drop. For example, assume a 100k load.

150 / 100k = 1.5 mA

P = V * I -> V = P/I

In this example, we have said the max power your source can supply is 100 mA, so:

V = 0.1 / 1.5^-3 = 66.7V

As you can see, you have exceeded the max power of your source, and your voltage levels took a hit and fell from 150V to 66V.

To make this simpler, check your load and see how much power it consumes. If you're plugging in a TV or a space heater, see how many Watts it consumes and then make sure your DC source on the primary can supply that many Watts.
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P: 11,911
 Quote by tefavolc how can i make the voltage constant what ever resistance i put?????? shokrn mokdamn (thnx in advance) :D
 Quote by Redbelly98 You can't.
 Quote by tefavolc why??!!would u plz explain
Every voltage supply has a maximum output current. If you choose R small enough so that Vout/R is larger than that maximum current, the output voltage must drop to a lower value.