Quote Originally Posted by LiquidVX
I wish for buttons. But it seems I am out numbered.
Buttons aren't a far jump from a knob. The knob just integrates all of the buttons into one fixture.

The TOD's e-clutch slips itself. It's kinda hard to explain without going full nerd. Each "cycle" or period lasts for 20 milliseconds. If the E-clutch were operating at a 50% duty cycle, the clutch would be engaged for 10 milliseconds, then disengaged for 10 milliseconds, then engaged, etc...

Since this is a coil, it takes a millisecond or so to really "load up" when current is applied. To operate at 100% duty cycle would burn out this coil over time. There would be no "rest period". In 4hi, the coil is working at @90% duty cycle, this is the same as 18 milliseconds on, 2 milliseconds off, 18 on, etc...
Even at idle, there is a brief surge of current every 20 milliseconds. So, in "2wd," there is a little bit of e-clutch engagement.

My first circuit went wild with the higher duty cycle. After 24 hours or so (this will never really happen in real life), the frequency shot up in relationship to the duty cycle. In short, at higher duty cycles, the 20 millisecond period went up to almost 10 milliseconds. This means that the clutch was being pulsed 2 times as fast as it was designed to be. This is bad. I'm bench testing another design that I found on the web. It'll probably work because a.) it's simpler, and b.) I didn't design it (I'm a mechanical engineer, I shouldn't be fooling around with electricity).

I have no intention of building these things "ready to install." Frankly, my time has a cost, and if I were to spend 2 hours putting it all together, we would suddenly crack the $$ barrier. Figure in the components (still less than $10-15) and shipping and it becomes unreasonable.

I'd like to provide the schematics, as well as a PCB (printed circuit board) layout. I could even burn the PCBs here if there's enough interest. Each person would be responsible for finding the components (if it can't be bought at Radio Shack, I'm not using it), and assembling the controller. There will be some soldering involved. I'll be able to provide some nice pictures of the finished board so component assembly will go smoothly.
This should be no more complicated than those electronic kits that you can buy for your kids (like the DIY lie-detector or the DIY burglar alarm).
The real difficult parts were getting the data together and determining what duty cycle corresponds to what torque split. Now that that's done, it's just a matter of putting all of the pieces together.