Peltier supply question

[Smokio]

Hi Guys I am pretty new to electronics, I have a basic knowledge and for the rest I am learning as well as I can

I have a project that needs cooling, a ccd camera. This I did with a 5v peltier element on the ccd itself, with a chunky heatsink, and the biggest fan I could find, a 12v computer fan. Is there any way to power them both off a 12v power supply without too much trouble? A peltier control board is off the cards (too expensive) I doubt I can make one. I tried to drop the voltage with just a resistor but the peltier resistance varies wildly with temperature.

Help a noobie out

 

[cowana]

What power is the peltier element?

Or, how much current does it draw (peak)?

 

[Smokio]

I just checked. It is a 4.2v element, rated to a max of 10W. Thanks for the quick response

 

[cowana]

4.2v at 10W. That's 2.4A.

To go from 12v to 5v at 2.4A means dissipating 17W of heat if you want to use a linear regulator. That's a lot of heat to remove - I think your best bet would be a switching regulator - such as an LM2596.

Andrew

 

[Smokio]

Thanks for the tip, Andrew. Would this be possible to wire in parallel with the 12v fan without any other issues?

 

[cowana]

Yes - parallel with the 12v fan would be ok, but the regulator circuit might need an additional capacitor or two if the fan is introducing noise into the circuit.

Andrew

 

[Smokio]

Ok ill try it out, thanks for your help

 

[Boncuk]

10 or 20W might be sufficient to cool your camera.

Please consider condensing water possibly flooding your device.

 

[Smokio]

Well mission complete, but I did find another problem that is present with both power supplies. There is noise on the screen when the peltier is turned on. The case is plastic, the camera chip is on an entirely different circuit to the peltier chip. Any ideas? Thanks again guys.

 

[cowana]

Are you able to add some 100nF decoupling capacitors across the supply pins of the camera?

 

[Smokio]

Sure can, but I have no idea where to place them. I did a little reading on them. The camera is powered by USB, the peltier by a power supply. I have to admit I do not understand how this works, when you say across, how do you mean?