Monday, November 29, 2010

Second glove... no field test yet.

Did the second glove.
Resistance is 18.0 ohms so it is pretty darn close to the other glove (without measuring the wire length before sewing it...)

Also did the Y-wire for connecting both gloves to controller.
Oh, and the controller is ready... sort of. Still needs to be soldered together but on breadboard it works just fine.
The only problem is: it is a single channel. And the reason for that is laziness...

Heat controller is microcontroller-based. PIC18F2580 has a builtin PWM-module, ADC input reads the value from 10k potentiometer and sets the PWM duty cycle based on potentiometer position, logic level MOSFET, connected to PWM output, controls voltage flow to gloves.
Could not be simpler than that.

In the test setup above, PWM duty cycle (Max) is about 300uS, period is 1.3mS. That gives gloves 6.7volts and that makes the wire to heat up to 48C-degrees.
Turning the potentiometer counterclockwise turns the heat down.

Next I need a plastic box to house the electronics.