Power amplifier

Discussion in 'General Electronics Discussion' started by Mads, Apr 11, 2013.

4
0
Apr 11, 2013
Hi forum

I have a 0-5v (DC) signal with properly only around a few mA. And I want to transform that to 0-12v with 10-15Amp. Is that easy? and what is the name of the device that can do that?

I have seached the web for the last two hours and I cant find anything that can help me.

Thank you! :-D

2. duke37

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772
Jan 9, 2011
You cannot transform a low power signal to a high power.

Do you mean that you wish to control a high power supply to give an output of up to 12v at up to 15A/

4
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Apr 11, 2013
@duke37

yeah that I exactly what I want. A power supply where the output is controlled based on my control signal. Does such a device have a specific name?

4. (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,501
2,841
Jan 21, 2010
The device is a MOSFET.

However there's more to it than just connecting it up.

It may be better to use a transistor and a relay for example.

We need to know more:

1) Do the signals have a common ground?

2) what voltage drop across the switching element is tolerable?

3) how often (times per second, per minute, or per day) will it be switched?

4) what is the load (we need to know if it is undefined, or if it may be capacitive or inductive.

5) what does your 5v signal look like (square wave? rise and fall times?)

Last edited: Apr 12, 2013
5. BobK

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Jan 5, 2010

Is the signal either 0V or 5V (digital) or anywhere within that range (analog)?

Bob

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Apr 11, 2013
@BobK
My signal is a analog 1-5V signal (and not 0-5V as I said before).

@(*steve*)
I think I mislead you into thinking that my signal was digital when it is actually analog

I'll try to draw what I mean:

if inputsignal = 1V, then output = 2.4V (High current, +10amp)
if inputsignal = 3V, then output = 7.2V (High current, +10amp)
if inputsignal = 5V, then output = 12V (High current, +10amp)

7. BobK

7,682
1,688
Jan 5, 2010
Basically, you need a high power opamp.

They exist, but they aren't cheap.

High Power Op Amps at DigiKey

Alternatively, you could try to make it yourself, using a normal power opamp and a push-pull power darlington output stage.

Bob

8. BobK

7,682
1,688
Jan 5, 2010
On second thought, you need to answer Steve's questions as well. If the signal only changes slowly, perhaps a voltage controlled power supply is the answer, and if it changes too rapidly (1MHz or higher) even an opamp solution will be very tricky.

Bob

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Apr 11, 2013
BobK

Thank you for your answer - I'll be googling high power opamp.

It changes really slow so that shouldn't be a problem

10. BobK

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Jan 5, 2010
So another, much cheaper, option is to build a regulated power supply and use the 1-5V signal as the reference.

Here is a supply design that would be suitable:

http://ludens.cl/Electron/Ps20/Ps20.html

You would just take out the zener based reference that goes to the - input of the op amp and replace it with your 1-5V signal and adjust the pot to get 12V out with 5V in.

Bob