Killing off this Blog

I'm going to go out on a limb here (not really) and call this blog officially dead. The original 3WDM (since converted to a 4WDM) was stolen almost a year ago, and I haven't been able to get myself excited about re-building it. It may or may not come back in radically different form at some point in the future.

You might find some of the archived posts useful, so they'll stick around, but If you'd like to contact me about anything on this blog, please jump over to my personal web site.

Great Discussion of Hub Motors

I just found a really good, comprehensive, and understandable discussion of hub motors (specifically for ebikes) on the UBC Electric Bike Club's site. Actually the whole site is worth reading.

Strain Gages have Landed

I've just received a set of ten strain gages that I'm hoping to use to replace the force-sensing resistors that I've thus-far been using to measure the rider's (my) weight distribution.

The force-sensing resistors have worked quite well other than the fact that they tend to slide out from between the deck and the frame. Another issue is that the circuit I've been using to drive the servo amp doesn't have enough gain to be really effective.

The strain gages will go on the frame's crossbars, and I'll remove the mounting bushing at the center of the deck, so that the weight of the rider will be on the crossbars. The gages will measure the miniscule flexing of the crossbars and a pair of instrumentation amplifiers will amplify this measurement to a level where it can drive the servo amplifier.

It takes a good bit of finicky prep work to mount, hook up, and seal the strain gages, but I will post an update when I've got them installed, and another when I've got them driving the servo amp.

I'm (In)Famous!

The good news is the 3WDM has made the front page of Skateboarding Sucks. The bad news is it's tagged as Stupid Shit and Useless Toys. Damn, skateboarders can be harsh!

Well, as they say, bad publicity is better than no publicity. And what is exactly is a skateboard if not a "Useless Toy"?

New Photos

I have some new photos up on Flickr.

Similar Product

Here's a similar three-wheeled electric skateboard, with hands-free control. As near as I can tell, the button in the middle is the "go switch" and the brake consists of stepping on the rear fender. Not as intuitive as the 3WDM, but admittedly a heck of a lot cheaper.

Looks interesting, but it's not something I'm ready to fork out $130 for.

New Remote Unit

I replaced the previous keychain remote unit (about the size of a jumbo pack of cigarettes) with a new one not much bigger than a matchbox. The new one also has the advantage that it's a simple push-on push-off unit, rather than one designed to drive a power door lock switch.

(Note for new readers: The remote doesn't really do anything other than power up the electronics. Controlling the thing is strictly hands-free thanks to the weight sensing controller. But it's a little tricky to step onto the board when it's active, and bending over to flip a switch is just too undignified).

I bought the thing from All Electronics, a company in Van Nuys whose previous store (in downtown LA) I visited a few times when I was in college. The store is definitely worth a stop if you're in the neighborhood, and the catalog and web site are also worth a look if you're looking for fun, cheap electronic components and doodads.