Re: Seat heater switches

[four.rings@mcione.com]

Huw Powell wrote:
> 
> > The seat heater switches in the ur-quattro are the thumbwheel type -
> > On/off when moving from 0 to 1, and then gradually more heat up to
> > a setting of 6.
> >
> > Anyone know the nominal resistance for each setting?
> 
> The resistance of the heater wire?
> 
> Because the switches like that that I have seen are just that -
> switches, with 7 positions.  They go to a pair of relays, then to the
> three heater wires.  The six settings are the different combinations of
> the three different resistance wires...

Mmmm, not exactly. At least on Type-44.

First off: ea. heating element is about 1 ohm (easily solderable - see my
detailed post of about 3 years ago). There are two of them in series (the butt
warmer and the back warmer), hence if one breaks - you ain't gonna indulge
yourself in sybaritism no more :-)

Secondly: the switch regulates not the amount of emitted heat (the heat is
constant as a function of constant resistance and the constant voltage) but the
time during which the heater is turned on.

The timer is built into the "relay" and receives the feedback from a
thermoresistor sewn into the heating element.

Although this heating setup has some small built-in hysteresis, it has a rather
annoying propensity to click on and off near saturation.

-- 
Igor Kessel
Two turbo quattros