Homemade heated vest controller?
 

I just got a hand-me-down heated vest. It has no controller. I looked at the site and they are available, but I don't want to spring for the $70.- for it. I could bodge up a really Neanderthal resistance based controller, but they end up dissipating power in the added resistors. So I was thinking that I could do something micro-controller based that would control the heat by varying the duty cycle. I should be able to use some power transistors as a switch and they would not dissipate much power, or I could go with a relay based solution. I was also thinking that I could incorporate a thermal sensor and create a feedback loop. Issues: my EE skills are poor at best, software is what I do. Anyone have any pointers or suggestions?

Re: Heated vest controller
 

Research pwm controllers.

Re: Homemade heated vest controller?
 

I'd use an atmega328
Link the ADC to a variable resistor or some sort of lo-hi-off 3 way switch, then one or two mosfets to control it through pwm

You might also want to look at arduino, it's a slightly higher level programming language. I've been using C for some diving stuff and to be honest it's giving me indigestion. By the time you've finishd you might wish you'd spent the $70... will be fun though!

Re: Homemade heated vest controller?
 

Or just have a switch. If cold torn to -On. If warm enough turn to - Off. Replace with a thermostat inside the jacket if you find you are turning it on/off too often. Or are the elements so powerful you'd end up basted?

Re: Homemade heated vest controller?
 

Sounds like vast overkill for a heated vest. Just use a variable duty cycle oscillator (ICM7555?) and a high current FET switch. If you're not warm enough turn up the duty cycle.

Re: Homemade heated vest controller?
 

That would probably be a better and cheaper alternative :)

I should add the caveat to my earlier post "I know nothing!"

Re: Homemade heated vest controller?
 

I've been looking into arduino, especially since I'm contemplating a brake and turn signal controller also. I enjoy C, haven't done it in a while. Don't much object to paying the money per se, just to paying it for a pot and a couple of wires.

Re: Homemade heated vest controller?
 

The resistance on the elements is 3ohm so max dissipation wil be about 50W, so should not cook. Besides I like to take projects like these as opportunities for learning, e.g. about power MOSFETS, software controlled feedback loops, sensor interfaces, etc.

Re: Homemade heated vest controller?
 

Plenty of stand alone off the shelf 12V pwm controllers available for pennies, like this for example . They are often described as motor speed controllers. At that sort of money I wouldn't bother messing about making anything, just put it in a box.