So, I just got my hands on a Big Trak Jr from Thinkgeek.
The Big Trak boxed up. Let me open it already!
The Big Trak was a programmable toy robot which was released in 1979. Over 30 years on, and now we see the second coming. A smaller version, which I believe has many of the original features, and at least one extra one – the accessory port.
I never owned an original Big Trak, I don’t even know if they were sold here in Australia. I bet they were expensive too. A heck of a lot more than the $24.99 +pp I paid for the Jr. I wish I did though, these things are pretty awesome. At that price, they are not just great value, they are a viable hackable robotics platform. If you don’t want to keep the controls, scrap it all, add a PicAxe or a small arduino, and bazinga!, a fully programmable autonomous robot!
I hadn't owned it for 24 hours before I'd unscrewed the top! I've just got to see whats inside!
After less than a day of playing with it, the curiosity got the better of me, so I decided it was time to bring out the screwdrivers to see whats inside. I had 2 goals,
1) Have a look inside
2) Try to work out how the accessory port works
Here is the underside of the accessory port. The whole port comes out easily just by removing those two screws!
6 Philips head screws was all it took to get the case off, and straight away I liked what I saw. There was just 2 wires that went to the accessory port. A black one, and a red one, and they connected to a standard 3.5mm TS (mono headphone) connector. It didn’t look like there was going to be any fancy communication protocols, or proprietary connectors to deal with! They couldn’t have made this easier!
A little probing with a multimeter showed that it was outputting a bit below 4v. I Didn’t measure the battery voltage to see if it’s outputting full battery power thru to the port or not, that will be something I should test later on.
So knowing I have a simple on /off port, I hooked up a LED. First by touching the LED to the terminals on a TS jack that I had plugged into the port, then after I worked out which way to connect the LED, I soldered the LED onto the TS jack, so it stuck neatly out the top of the jack cover when it was screwed on
And here is the little LED on a plug which I made, and how it is wired.
Then it was testing time. Plugging in the LED, and turning the Big Trak on, I programmed in a trigger output, and the LED lit up just as it was supposed to.
Now I’ve gotten the LED to work, what’s next for me? some other kind of device. Maybe a motor? a DIY rocket launcher? extra machine guns? The choice is almost unlimited. I’ll have to see what I have kicking about.