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...