TOD controller - knob, wheel, or buttons?

[Maugan_VX]

Oh ok, I was wondering if you were coming up with some new slick display for it.

I know what you mean about real life getting in the way of fun. Ack.

[Velvis]

How 'bout we agree to only bug him once every couple of weeks? OK, how 'bout NOW??? Don't worry beach, we'll wait for genius. (We'll wait longer for new slick display, though.)
v

[mbeach]

I still donate a few hours every couple of weeks to this project. We are ramping up for our summer project season, so despite the 21+ hours of daylight, I'm still running out of time to get things done.

[mbeach]

TTT

Here's where I stand:
I made two circuits, both capable of varying the duty cycle of a 20Hz pulse, from 5 to 90%.
One ran perfectly, varying the duty cycle without changing the frequency. At 7 volts. Once the V came up to 14, a FET got unstable. Radio Shack doesn't carry a higher power option. I can find one, but the average guy doesn't have the same resources as my shop.
The other one could handle 14V no problem. It managed 5 to 25% duty cycle without a problem. Any duty cycle higher than that caused the frequency to drift. At 90% dc, the modulation had gone from 50 to 250Hz.
The e-clutch no like "high frequency".
Keep in mind, both of these circuits were built only with parts that could be easily found and assembled. No digital ICs, PICs or anything of the like. This is all Radio Shack stuff, and as a result, it sucks.

I've found another option, based on a comment by a member regarding a DC motor speed controller. I found a $25 kit that allows you to build your own. It has a transistor and a MOSFET that are kinda odd, but it ships with all of the components needed to work, so no part sourcing required.
It will require 4 components to be subsituted, to change the operating frequency, but they are easy to come by.
I think that this'll work -and best of all, it's designed to be assembled by someone who has no more than basic soldering skills at hand. I've ordered 2.
I'd build a prototype based on it's schematics -but I'm missing one component, so I'll just wait until the kits arrive.

I've managed to switch my TOD display (the interface) along with the movements of a 4 position switch. It was actually easier than I thought that it would be. Getting the display switch to jive with the torque splits will be a little tougher. Again, I'm waiting on those kits to show up to see if I can jam it all together.

To sum up:
If you want 4hi only; you'll cut one wire. Put in a switch, a load, and the PWM generator and you are there.
If you want 2-4 control; you'll cut one wire. Put in a switch, a load, the PWM generator, and a rotary switch, and you are there.
BUT if you want a working display, you ALSO have to tap into 4 additional wires, and work these in to the rotary switch.

I'm making this sound tougher than it is -I apologize. I just need a rainy day and those kits to finalize everything. I still have my "eavesdrop" cable sticking out from under my passenger seat, just waiting to do some good.

[Tobert]

You can create parts lists for digi-key that are pretty much one-click to fill your cart if I understand properly. I've been eyeing the Megasquirt kit for a while now to mess around with but haven't had a vehicle I really wanted to mess with in a couple years.

http://www.megasquirt.info/
http://www.megasquirt.info/v3bom.htm

http://www.digikey.com/

This way you could source whatever parts you think are appropriate and anybody here can easily order them.

[darkl4805]

So basically the switch will let you choose TOD Off, TOD Auto, TOD 15/85, and TOD 50/50?

Is there a front differential? If not what happens to the built up tension?

Very cool work, put me down for one whenever you are done!

[Groovium]

Truly & duly groovy! Sign me up -- those long highway hauls on cruise control would benefit from the (properly elegant) cutout frobulator...

[mbeach]

You can create parts lists for digi-key that are pretty much one-click to fill your cart if I understand properly. http://www.digikey.com/

Digi-Key is one of my usual suppliers for work. I wanted to avoid too much "parts shopping" by the members -it just gets too confusing with similar part numbers and interchangeablity.

Is there a front differential? If not what happens to the built up tension?

There is a front differential. This part (2wd) of the mod will just prevent the TOD clutch from modulating. If the clutch provides no friction (and your front hubs are unlocked), there can be no torque sent to the front driveshaft. It might spin, but without resistance (either from the clutch or the wheels) there will be no torque. This is the fundamental principle that allows the TOD to work.
Example: You're driving some old rig with an open rear differential. You drop one rear tire into a hole, and the other is just hanging in the air. You're stuck. The tire that's in the air is just going to spin -until you apply the brakes a little. This brake friction will redistribute the torque to the wheel that needs it -the one in the hole. This technique (using the brakes -ABS- to modulate individual wheel torque) has been in use for a decade or more. Land Rover might still use it. The VX's TOD works on the same principle, but it's front to rear instead of side to side.

[ZEUS]

Hey mbeach, I don't mean to be pushy but I was curious about the progress you might have made on this invention of yours... Had any developments?