# I want to convert 3mv output to 5 Volts

#### Sankalpsood

Joined Jan 19, 2016
9
I am making a project to use seabeck effect to run a 5 volt motor to run a fan.
But the problem is that , the output voltage by Seebeck effect is around 3 millivolts. So I basically need a circuit or a device to amplify that to 5 volts.

#### Sankalpsood

Joined Jan 19, 2016
9
That is 5 volts not brother.. #sorry

#### Sankalpsood

Joined Jan 19, 2016
9
not any op amp circuitry can work?

#### crutschow

Joined Mar 14, 2008
27,232
not any op amp circuitry can work?
It can certainly amplify the voltage but the op amp power must be supplied by external power supplies

#### profbuxton

Joined Feb 21, 2014
419
Just use a thermocouple amplifier. Standard product available from instrument companies. Will output 4 to 20 ma or 1 to 5 volts(or other)

#### Papabravo

Joined Feb 24, 2006
16,165
Amplifiers cannot make something out of nothing. The power, in watts, produced by ANY circuit is always less than the power in. Sometimes it is much less. Just to throw out some numbers let us assume that your device can produce 3 mV @ 100μA. The power input is 300 nW. Let us say we achieve the incredible efficiency of 80%, the power out will be 240 nA. This power level at 5V will result in an output current of 48 nA. I can tell you that that amount of current will NOT be able to turn a fan.

This idea is not dissimilar to the idea of harvesting "free RF energy" from our surroundings. They are both tasks of monumental futility.

#### Picbuster

Joined Dec 2, 2013
1,027
look at the TL site or microchip use 3 x mcp6n11 3mV in last stage 5V out but you have to use a noise free pwr supply.

#### Kermit2

Joined Feb 5, 2010
4,162
POWER is a product. It can be estimated by multiplying a voltage and a current.
The product is called watts or volt-amperes.
IT CANNOT BE INCREASED by amplification.
Volts can be increased but current will decrease.
Current can be increased but volts will decrease.
Always, if you multiply, the two you will get the same answer.
POWER cannot be increased by an electronic circuit of any kind.
To increase power, more power must be added.
Consider your stereo. The audio signal you put in the back panel is not capable of moving a speaker cone. The signal coming out is much more powerful.
Look at the wall socket where the amp is plugged in and tell us where this increased audio power comes from.

#### Papabravo

Joined Feb 24, 2006
16,165
Think of an amplifier as an electronic copy machine. It makes a copy of a low level signal by using the power from the wall socket. As always the power out will be less than the power in.

#### ErnieM

Joined Apr 24, 2011
8,153
If you place 1,667 thermoelectric devices in series you will obtain your desired voltage without amplification.

Good luck getting any appreciable current out of it.

#### tcmtech

Joined Nov 4, 2013
2,867
If you place 1,667 thermoelectric devices in series you will obtain your desired voltage without amplification.

Good luck getting any appreciable current out of it.
Well if they are configured as a common 12 volt 50 watt or larger Peltier unit 5 volts at a few hundred milliamps or more would no be hard at all.