# Is there current multiplier circuit?

Is there an electric circuit that can multiply the input current? if yes, what is that called, and how to make it?

My input is DC from a small DC motor which I use as a generator.
My input current is 300 milliamps and I need 1200 milliamps as output. Is there some way to increase the output to 1200 milliamps ?

• Welcome to Engineering Stackexchange. Can you please tell us the engineering problem you are try to solve? Also a you can do a simple good search and get a good listing of suggested articles. Here is link Current multiplier/divider for current measurement? that might give you some insights. Consider improving the question – Mahendra Gunawardena Jul 19 '15 at 10:43
• Tell us what you want to do and we can probably tell you how to do it. Ask a semi random question about the existence of something, or how to design an electronic solution for an unspecified problem, and the answers are liable to be more misleading than useful. – Russell McMahon Jul 20 '15 at 13:24
• Here are the things I need. My input is DC so transformer cannot be used to step up the current. My input is from a small DC motor (I use the motor as generator) so i have only single input. my input current is 300 milli amps and i need 1200 milli amps as output. I need a circuit to do this job. – user2338 Jul 20 '15 at 15:49

## 4 Answers

My input is DC from a small DC motor which I use as a generator.
My input current is 300 milliamps and I need 1200 milliamps as output. Is there some way to increase the output to 1200 milliamps ?

With out using external energy input you can transform voltage or current but you can not increase the power level. As power = voltage x current, that means, if voltage is increased then available current is increased, then available voltage but decrease. That is

• Power in >= Power out so

• Vin x Iin >= Vout x Iout

Usually power out will be less than power in due to inefficincies in the conversion process.

In your case, imagine that your generator makes 300 ma at 6 Volts.
Power in = 300mA x 6V = 1800 mW.
Power out must be <= 1800 mW.
For Iout = 1200 mA, Vout must be
Vout <= 1800 mW / 1200 mA = 1.5V So at 1200 mA out the voltage out is <= 1.5V.

The conversion could be carried out by a 'buck converter' which reduces output voltage and increases output current.

Good buck converters can be in the range 90% - 95% efficient so in this example, at 90% efficient:
Input = 6V, 300 mA
Iout = 1200 ma.
VOut 6V / 4 x 90% = 1.35V

If you want more current AND more power you need to "change the laws of physics" (Recommended :-). (Reference to 'change the laws of physics at 2m:25s but some (but not all) will find the whole 3m33s worth watching (once, anyway).)))

Your specifications are very loose, so yes, there are circuits and even passive devices that can produce a higher current out than in. Such a circuit is called a amplifier, and a transformer is a example of such a passive device.

As to how to make either of these, that is beyond the scope of this question. There should be much information on these and other devices out there.

I get the impression that what you are really looking for is a way to achieve more current at the same voltage. You cannot do this from a single generator. But what you can do is add another generator in parallel to your circuit. This should double the available current while keeping the same voltage. Of course, this assumes that you can operate both generators at the same speed simultaneously, which can be quite remarkably more difficult than it sounds and may not be feasible for your application's needs.

yeah, there is a method to multiply both amperage and voltage at same time using motor-generator combination, but the current value is badly less for motor-generator combination to work out well. say like a 400 watt alternating current input can be amplified to 1200 watt direct current output. a 250 watt direct current input can be amplified to 24000 watt direct current output.

• No device can put out more energy than is put into it. You can't just drive a motor generator, for example, in steady state with 400 W in and magically get 1200 W out. Physics can be inconvenient like that. – Olin Lathrop Dec 23 '16 at 17:41