Amplifying Millivolts to Volts

[Caiden]

Hi guys, I trying to amplify 10 millivolts into 1 or more volts I was wondering if anyone knew how to do that. I'm really in a rush so please resond quickly.

 

[kam1787]

at what current? what frequency? what supply voltage?

probably an op-amp is the easiest

http://en.wikipedia.org/wiki/Operational_amplifier
**broken link removed**
http://www.radio-electronics.com/info/circuits/

 

[Caiden]

I've tried an op amp but i can't seem to get it right. where is the ground for the output? do you know any circuits that I can use that will work? I'm trying to amplify 10 millivolts to make it usable. So basically I can amplify it to ac just as long as it's 110v (thats usable) or enough dc voltage to charge a phone.

 

[Audioguru]

A phone charges with 5V at about 500mA. It uses a power supply, not an amplifier. The charger circuit is inside the phone.
If you want to make a 5VDC power supply that plugs into 110VAC then you need a 110VAC to 8VAC center-tapped transformer rated at 2.8VA, two rectifier diodes and a 1000uF/16V filter capacitor.

What is the 10mV frequency and where does it come from? What do you need 1V for?

 

[FvM]

I'm trying to amplify 10 millivolts to make it usable. So basically I can amplify it to ac just as long as it's 110v (thats usable) or enough dc voltage to charge a phone.

Sounds like you are targetting to "energy harvesting" which wasn't obvious from your initial post. "Amplification" usually describes increasing a signal level with the help of an external energy source. Increasing the voltage of an energy source is in contrast called energy or power conversion.

Are you aware of the fact that you can't create energy this way? Presumed you have 10 mV with 10 mA current capability, this corresponds to a power of 100 µW. If you are able the voltage level to 1V, the available current drops to 100 µA (or less, due to below 100 percent conversion efficiency). So you'll hardly be able to charge a phone.

 

[Caiden]

Sorry I didn't know that there was a difference between power conversion and amplification. My 10mv is coming from RF that I'm getting out of the air.

 

[Audioguru]

10mV is a strong radio signal and a radio can easily amplify it but the current is almost nothing, therefore its power (voltage x current) is almost nothing. You need about 2.5W to charge a phone and your 10mV is WAY TOO WEAK.
For an amplifier to produce an output of 2.5W then its power supply must power it with about 4W. Then 1.5W is wasted as heat. Where will the 4W for the power supply come from?