Heater strap controlled by Arduino

Hi all. I'm looking to make some fabric heat straps to warm my camera lenses above dew point on summer nights.

I'm going to use some nichrome wire and would like to be able to vary the power to it via a Arduino. The wire has not arrived yet for testing but from calculations I think that I will need to supply around 500-800mA of current at 12v.

I would like to be able to vary the output power (say 0-100%) but I'm not sure on the best approach?

Thanks in advance

analogWrite would be one way to do it.

Thanks wildbill. So maybe a power transistor or something and use analog write to vary the power going through it? Any suggestions for a suitable transistor?

Many thanks

I can't suggest a transistor but yes, you'd want a power transistor with a power rating comfortably above your expected current draw.

Just FYI analogWrite doesn't actually output an analog voltage; rather, it's PWM (Pulse Width Modulation). Actually that's good in your case, because switching a transistor full on and full off with PWM is far more efficient than running it in the linear ("somewhat on") region.

This going to be battery powered?

dtokez:
Thanks wildbill. So maybe a power transistor or something and use analog write to vary the power going through it? Any suggestions for a suitable transistor?

Many thanks

If you are an electronics newbie then a module like this does it all for you

Remember this is an N Channel MOSFET so you will need to switch the negative not the positive - but otherwise a no brainer

Craig