On Wed, 9 Sep 1998, Bill Richman wrote:
> I believe you're talking about the Mattel "Big Trak"? My nephews had one of
> those many years ago.
Mine is labeled Milton Bradley. I still have my Big Trak, its box, and
its manual, and although some of the axils are busted, it still works!
> I believe it used tank-type steering; six wheels, and it could either lock
> one set and pivot using the others, or reverse one side.
It has six wheels; three on each side.
The middle wheel on each side is a drive wheel. To turn, it turns one of
these wheels forward and the other backward. So it does a nice pivot.
> I've got some surplus gearboxes and motors from the Big Trak that I
> purchased several years ago. They're kind of neat; they have two motors and
> gear trains, linked together with a couple of big magnets. If you run both
> in the same direction, the magnets are strong enough to force both motors to
> turn at the same speed. If you reverse one of the motors, the magnets
> alternately repel and attract. This either forces the machine to drive in a
> straight line, or to pivot about its center, respectively. They also have
> an optical interrupter on one gear so the CPU can tell how far the motors
> have turned.
Cool! The turning never worked that well for me, but I think it had more
to do with uneven floors than with the Big Trak. A value of 15 was
supposed to do a 90 degree turn, but sometimes it took 14 or 16 and it
made programming difficult. I had to keep re-entering the programs for a
particular patch of floor, and the effect of just having it follow me into
a room and shoot someone of my choosing was lost. :)
My Big Trak's biggest problem was (and is) breaking plastic. First it was
the tabs that held the D cells in place, then it was the front axil, then
one of the back axils.
When I play with it now, I hold the batteries in place by forcing a
broken popsicle stick into the hole in the cover, which acts to keep the
plastic tab in place. Eventually this might stress the plastic and cause
more breakage. :/
The front axil is held together with electrical tape.
The back axil has been drilled through and bolted into place. It was a
repair my father made when I was a kid. It's not quite straight, though,
so the wheel doesn't turn freely.
But it's still a cool toy. I drag it out about once every two years and
have it drive around the house.
When I was a kid I had some sheets of paper that I had written programs
on, but those must have been tossed out or recycled years ago.
> It had a hookup to dump the trailer, and I think some other
> options that never were released. It was a pretty cool toy.
The trailer was the Big Trak Transport. It looks highly breakable. :)
> A quick web search found this:
>
> BigTrak User's Guide:
> http://www.comp.lancs.ac.uk/computing/courses/year3/358/cwk/brown/BT_UG/
>
> BigTrak Simulator Project:
> http://www.comp.lancs.ac.uk/computing/courses/year3/358/cwk/corke/
>
> BigTrak Repair Service:
> http://www.lavalamp.demon.co.uk/bigtrak/bigtrak.htm
I'll have to check these out. :)
> Bill Richman
> incolor.inetnebr.com/bill_r
> (Home of the COSMAC Elf
> microcomputer simulator!)
Doug Spence
ds_spenc_at_alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/
Received on Mon Sep 14 1998 - 03:04:42 BST