Will this wire burn me or melt my clothes ?

[DrAlloway]

That RV Accessories dimmer looks good - it says 12vDC and that it saves energy (by which I deduce that it is some kind of PWM like the schematic provided above).

I did tease some info out of a commercial maker's tech support before they shut me down.

Guy said the frequency needed to be like 1 Hz, otherwise the simple regulators on motorcycles get confused. The frequency on light dimmers is typically above 60 Hz so the eye doesn't notice it is really being turned off and on, rather than dimmed. I have no idea if 60 Hz is OK or not - as the bait I threw at tech support mentioned thousands of times per second.

But keep thinking guys - the right answer IMHO - is CHEAP.

 

[Imposter1]

I'm looking to make my own battery-powered heated fingerless gloves for working outside in winter, and this thread has been helpful, as has the similar guide at instructables.com.

I'd like to recommend this inexpensive pulse width modulation dimmer (designed for LEDs), which may be the heat control you're looking for. The pwm will modulate the heat without lowering the voltage or output power. http://www.usledsupply.com/shop/led-controllers-dmx/controllers-dimmers/pwm-3a-uc-dimmer Or search for other pwm LED dimmers, which may fit your dash better. They all seem to work with 12V DC input.

The instructables article is here: http://www.instructables.com/id/DIY-heated-clothing/

Best of luck.

-Imp

 

[DrAlloway]

Wow - excellent find - I looked for a cheap PWM for 12vDC and couldn't find one. So I designed my electric motorcycle clothes with multiple circuits - each with a different wattage - so I just plug in whatever circuit is appropriate for that day's weather.

If I had this PWM when I started I would have designed it differently. They also have 8 amp models. The 3 amp would be perfect for gloves or socks. The 8 amp for jacket or pants.

Would make the whole project less complex and only add $20 for 3 amp and $25 for 8 amp.

Again, great find.

 

[aspardeshi]

try a temperature controller also and integrate in the circuit. it will get rid of your heating problems.

 

[sophiecentaur]

I would have said that it is vital to avoid high temperatures (hot spots) in the jacket. This means a long length of relatively thick wire which will dissipate the power at a lower temperature because it has a larger surface area and is in contact with more of the fabric of the suit. You can choose many combinations for a given resistance / power output; the choice will probably be the wire that doesn't cost too much - which would be copper, rather than anything else - you are after just a couple of Ohms (see below), which corresponds to quite a few metres of 'thinnish' wire. Enamelled, rather than plastic covered might be better as its temperature will not be too high and it won't melt the insulation. You will need to zig zag it so that it can stretch and move with your body. Sandwiched between layers of a material that isn't too insulating - like cotton - and it won't overheat or melt.
You could look inside an old 'electric blanket' to get an idea of suitable cnstruction.

Of course you need plenty of insulation on the outside of the jacket but you don't need much more heat supplied than your metabolism produces. You will overheat very rapidly if you have too much heat supplied. My opinion is that you only need 'just enough' to keep you comfortable. The 72Watts seems reasonable. If you wanted a rapid warmup, you could always do the old 'series / parallel switching' trick that old electric cooking hobs used. Two resistors in parallel produce four times as much heat as they will in series.