# The Naked Scientists Forum

### Author Topic: Can I build a circuit that increases voltage?  (Read 4345 times)

#### thedoc

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##### Can I build a circuit that increases voltage?
« on: 16/10/2015 22:50:01 »
Can you help me? I want to build a circuit that can increase the voltage that I want such as 2volt DC to 5volt DC. I have no idea. For example the charger. It input is 240V and give 5V output.But I want to build a circuit that can give me 5V dc output but requires only 2V dc as the input voltage.This is for my final project. Please help me.I need the answer. Thank you.

What do you think?
« Last Edit: 16/10/2015 22:50:01 by _system »

#### alancalverd

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##### Re: Can I build a circuit that increases voltage?
« Reply #1 on: 16/10/2015 23:45:46 »
Depends on how much output current you need. www.ti.com/lit/ds/symlink/tl7660.pdf shows how to cascade two inductorless voltage inverter chips that will just work on 2V input.

If you need something robust that will work down to a lower input voltage, use a "trembler". This is a transformer wound on a linear core so it also operates like an electric bell self-interrupter. When a current flows through the primary coil, the magnetic field attracts an armature that opens the primary circuit and stops the current flowing. The collapsing magnetic field induces a voltage in the secondary winding, and the cycle repeats. You can use this to generate very high voltages - it is the principle of an oldfashioned  car ignition coil - but you will need to rectify the output with a diode to generate the required DC voltage. In principle a trembler will work with just a few millivolts of input, say from a thermocouple!

#### Bored chemist

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##### Re: Can I build a circuit that increases voltage?
« Reply #2 on: 17/10/2015 00:12:41 »

#### Colin2B

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##### Re: Can I build a circuit that increases voltage?
« Reply #3 on: 17/10/2015 00:45:07 »
If you can generate an ac voltage from your DC you could try using a voltage multiplier see https://en.m.wikipedia.org/wiki/Voltage_multiplier. I've used ccts like these to power portable radio transmitters.
Similar ccts can be called voltage doubles, so you might like to look up those too.
All depends on the current you need and can supply.

#### RD

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##### Re: Can I build a circuit that increases voltage?
« Reply #4 on: 17/10/2015 03:19:57 »
... I want to build a circuit that can give me 5V dc output but requires only 2V dc as the input voltage.

see ... https://en.wikipedia.org/wiki/Joule_thief
https://en.wikipedia.org/wiki/Boost_converter#Applications

NB: you can multiply voltage , but not power.
« Last Edit: 17/10/2015 03:22:54 by RD »

#### PmbPhy

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##### Re: Can I build a circuit that increases voltage?
« Reply #5 on: 17/10/2015 16:43:47 »
Can you help me? I want to build a circuit that can increase the voltage that I want such as 2volt DC to 5volt DC. I have no idea. For example the charger. It input is 240V and give 5V output.But I want to build a circuit that can give me 5V dc output but requires only 2V dc as the input voltage.This is for my final project. Please help me.I need the answer. Thank you.

What do you think?
Sure. Just use a step-up coil and then attached the output of the coil whose end has the larger voltage. Then you have to use a diode and a capacitor. The diode makes the current all go in one direction while the capacitor smooth's out the voltage.

#### alancalverd

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##### Re: Can I build a circuit that increases voltage?
« Reply #6 on: 18/10/2015 08:54:37 »
Pete: the lad is starting with a DC supply. All that will do is heat the coil. Or in your language

E = -Ldi/dt

#### Colin2B

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##### Re: Can I build a circuit that increases voltage?
« Reply #7 on: 18/10/2015 09:22:15 »
Pete: the lad is starting with a DC supply......
He needs a chopper in front of the coil Pete
And don't go misconstruing that

#### The Naked Scientists Forum

##### Re: Can I build a circuit that increases voltage?
« Reply #7 on: 18/10/2015 09:22:15 »