# How to step up voltage and current

#### hurais p a

Joined Jan 15, 2022
2
Am currently working on personal project which need to step up voltage from 3v to 24v.
Am working on a system with a small dc motor as a generator which is currently producing 3v, I want to step up the voltage and current so that the system can be used to operate any electronic device, I have tried to create some circuits which I saw on google but nothing seem to work.
I am expecting an helpful guidance to complete my project.

Joined Jul 18, 2013
25,017
If you are generating the voltage you are not going to increase the current capability of the source.
AC requires a transformer, but the current rating will go down proportional to the in crease in AC. or DC
With DC you will have to do that electronically with the same constraints.

#### Dodgydave

Joined Jun 22, 2012
10,244
You won't get more put than you put in, what is driving the motor?

#### dl324

Joined Mar 30, 2015
14,322
Welcome to AAC!
currently producing 3v, I want to step up the voltage and current so that the system can be used to operate any electronic device, I have tried to create some circuits which I saw on google but nothing seem to work.
Likely because it can't be done.

Power out = η (power in) and η can never be >= 100%.

#### MisterBill2

Joined Jan 23, 2018
11,621
There is this one physical limit, which is that power out can not exceed power in. That is made complicated by the fact that power = volts X amps. The very best you can get is to use that 3 volts through a converter to charge a battery to 24 volts. Then the battery could provide a lot of power for a while. Of course the trade off is in operating time. Watt-Hours out still can not exceed watt hours in, even if the charger and battery are 100% efficient.
How much mechanical power is available to spin that generator?
AND, how much power do you actually need at the 24 volts?

What engineering school did you attend? They may have courses that I missed.

#### BobTPH

Joined Jun 5, 2013
4,772
If you step up the voltage from 3 to 24V, you will get at most 1/8 the current.

Bob

#### MisterBill2

Joined Jan 23, 2018
11,621
The process needs an orthagonal multiplier with a lateral element of unobtainium.
Unfortunately the political unrest in the Utopian area has all of the mines closed, and so that metal element is really hard to get at this time. The alternative is to use a bilateral phase shifter system with an 8X multiplier coefficient.

#### Ya’akov

Joined Jan 27, 2019
5,534
This is just a repetition of what others have said but with a slightly different wording in case it helps.

Voltage (V) and current (A) can be multiplied to determine how much power, in watts (W), is available.

Power is the overall measure of the system‘s ability and, within limits it is possible to trade off V and A by various means. But, no matter how you do it, you must trade. So, ignoring unavoidable losses in the real world, if we have 1V at 1A which can have 2V at .5A or .5V @ 2A, or any other pair that gives us 1W.

The bottom line: given a power source you can increase voltage, or current, but never both because that requires more power than you have started with.

#### hurais p a

Joined Jan 15, 2022
2
This is just a repetition of what others have said but with a slightly different wording in case it helps.

Voltage (V) and current (A) can be multiplied to determine how much power, in watts (W), is available.

Power is the overall measure of the system‘s ability and, within limits it is possible to trade off V and A by various means. But, no matter how you do it, you must trade. So, ignoring unavoidable losses in the real world, if we have 1V at 1A which can have 2V at .5A or .5V @ 2A, or any other pair that gives us 1W.

The bottom line: given a power source you can increase voltage, or current, but never both because that requires more power than you have started with.
Hi,
Actually i am not looking to step up both current and voltage in a single circuit or step...
I was wondering will it be possible to forst boost the voltage from the DC motor, then convert the dc into ac, use a current amplifier, convert back to dc.....
Kindly advise if this process will work or not...

Joined Jul 18, 2013
25,017
Am currently working on personal project which need to step up voltage from 3v to 24v.
Am working on a system with a small dc motor as a generator which is currently producing 3v, I want to step up the voltage and current so that the system can be used to operate any electronic device, I have tried to create some circuits which I saw on google but nothing seem to work.
I am expecting an helpful guidance to complete my project.
If you really want to generate a suitable DC power level, then almost any DC motor will generate, there are many sources such out there from automotive to treadmill.
Pick one that will do the job.
You can even obtain a BLDC motor that will generate 3phase that can be rectified.

#### Ya’akov

Joined Jan 27, 2019
5,534
Hi,
Actually i am not looking to step up both current and voltage in a single circuit or step...
I was wondering will it be possible to forst boost the voltage from the DC motor, then convert the dc into ac, use a current amplifier, convert back to dc.....
Kindly advise if this process will work or not...
Please re-read what I wrote. What you want violates physical laws. You can't get more power out than you put it, and if you want to increase both, that requires more power than you have to work with.

#### k1ng 1337

Joined Sep 11, 2020
439
Perhaps TS is thinking of something like stepping up voltage and then adding to capacitor bank to achieve the current requirements in a sort of sequential manner for pulsed applications.

#### Ya’akov

Joined Jan 27, 2019
5,534
Perhaps TS is thinking of something like stepping up voltage and then adding to capacitor bank to achieve the current requirements in a sort of sequential manner for pulsed applications.
If any sort of accumulator is involved: capacitors, battery, flywheels, pumped storage, etc. then it becomes a matter of integration over time. But there was nothing to suggest that was the case. It appears the TS is looking to take the output of a generator an increase its power without additional power input, nor time.

But, that's a good point, and I didn't consider it until you brought it up, probably because nothing the TS said suggested it.

#### MisterBill2

Joined Jan 23, 2018
11,621
I mentioned charging a battery in post #5. That was not what the TS is seeking. Clearly stated, the goal is to get more out. Post #9 suggessts a current amplifier to apply once the voltage is raised by the transformer. But that is a special transformer as it will be about 800% efficient.

Joined Feb 20, 2016
4,115
use a current amplifier, convert back to dc.....
Kindly advise if this process will work or not...
Any amplifier you use has to have an external power supply to work. A current amplifier does not convert the input current to a larger output current.
It uses the input current to control the extra power supply to produce the larger current.
So, instead of starting with a low voltage, low power generator, just get a power supply or generator that will do your job.

#### AnalogKid

Joined Aug 1, 2013
9,965
... use a current amplifier ...

Everything you want to do, as individual circuit blocks, is entirely possible. The problems are that a) each circuit function is less than 100% efficient, so the total energy available at the output of each circuit block is less than what was at its input. Multiple power conversion steps in series always eats up a lot of the input energy in inefficiencies.

Separate from that, you need to think through that "current amplifier" idea, and look at whatever examples of it you have seen. Almost all have an external power source. The ones that don't are also voltage reducers, and power reducers.

The problem is total energy, whatever its form. Everything in your project is powered by whatever is turning the shaft of the generator, and the max energy the generator is capable of producing. When you look into that, you will see that, even with 99.999% efficient conversion stages, there is too little energy at the starting point to do anything that is actually useful.

ak

#### DC_Kid

Joined Feb 25, 2008
924
What's the rated power output of the 3v generator? That rated output (--> conversion) = rated output minus some loss from the converter.
3v on Load-A, and then 24v on Load-A, means the 24v setup is gonna try and deliver more amps (basic ohms law). The delivery however will not be greater than whatever the generator power out rating is.

Many ways to get higher voltage, but "buck-boost" design seems plausible.