Friday, December 31, 2010


Jacket liner is now wired and tested. Heats up nicely.
Still needs something like zipper, collar, connectors etc.

It has 11.6m heater wire (6 x 193cm) with 24.8 ohms per wire, connected parallel so if I calculate correctly resistance is about 4.1 ohms.
With 14volts it gives 47 watts of power?

Tuesday, December 21, 2010

Jacket taking shape.

Jacket is progressing nicely. Or perhaps "jacket" is not a right term here, it is more like flannel shirt with 16 meters of heater wire in it.

Wednesday, December 15, 2010

Jacket progress

Not a jacket yet but kinda backwarmer.
I have tested this now couple days (in the mornings, daytime is too warm) and it is absolutely marvelous.

Two 2.1meter (210cm) loops of resistance wire connected parallel (about 27ohms each), power directly from bike. That makes two ~7watt heating elements.
Heats to 34C.

Works ok if temperature is around +3C as long as speed does not go over 80km/h.
Over 80 it does not feel warm, I need to cut 10-20cm off from wires. That makes it run a little warmer, around 40C-50C max. Should be enough and it will also prevent burning if controller fails and connects battery straight to jacket.

Thursday, December 9, 2010

But how the box itself...

Just received components for heat controllers today:
Microchip PIC 18F2331
Potentiometers (how to make them waterproof?)
Logic level mosfets

Still one open item is: how the user interface should look/work? Lots of ideas but now when it is time to actually put something together... Yeah.

How about this:

How it works? Well...
Normally two rotary knobs in front controls the heat of two "channels" (gloves+jacket, boots+pants).
Two rotary knobs on top control the balance of heat on two areas: gloves/jacket and boot/pants.

Simple, eh? Ok, let me explain more: front knobs control the heat on upper and lower body.
Top knobs are just temporary. With them the heat balance can be adjusted (gloves vs jacket and boots vs pants). Once top part is removed (magnetically attached), front knobs raise/lower heat on respective body parts.

This design may change though...

Friday, December 3, 2010

Field test done!


What a difference!
Couple times riding to work in the morning in below 40F weather wearing these prototypes...

And once riding back from work them stuffed inside the jacket.

Yep. I will definitely make jacket liner, pants and socks (or insoles) too.

About the controller... After spending several nights with microcontrollers, oscilloscope, soldering iron, datasheets and several glasses of wine I realised I could do it with 555 timer chip and some passive components...

About 10 minutes later:

PWM controlled mosfet, kinda like dimmer, capable of handling up to 18 volts / 10 amps.

Overall cost (without cables and connectors but including the plastic box: $5).

And here is the prototype box in the left fairing pocket of my 'wing:

So what's next?
Do "final" gloves, jacket liner, underpants (or perhaps chaps?) and insoles (or socks).
Oh, and the controller. Two channel controller should be sufficient.

And then, perhaps, some kind of wireless thermostat controlled four channel version of controller... Actually it is almost ready but I want to get warm now, not when the software is ready...