The second smaller chip in 1979 model is certainly not a RAM chip, it's DS75494, which is a 6-channel 150mA per channel driver. it is there to amplify the signal for the speaker and lamp and to drive the speed sensor LED. The program only 16 commands in max length would have fit into 64-word RAM of the microcontroller. Since commands have a form of command type + command length where length is up to 99, i suppose they store command in one 4-bit word and length in two words, consuming 3/4th of the RAM. That and having the complete firmware fit into 1024 instruction words (8-bit) is some efficient programming.
One of my favorite toys as a kid. I even had the dump trailer. I'd spend so much time trying to create a programmed path from the kitchen to my bedroom.
The Soviet Union made a clone of this in 1983, and I owned one! It was called "Луноход Электроника ИМ-11" in english --> MOON WALKER IM-11. To this day, I had NO IDEA that the Bigtrack had a trailor.....for all these years, we as kids in Soviet Russia could not find out what the extra hitch was for on the Bigtrack, 37 years later, I find out lol What an amazing piece of history, I would kill to own one of these today. Thank you so much for sharing this!
Really nice video - thank you! Presumably the centre tap on the old version simplified the motor drive circuit and the voltages applied to the motors are relative to the centre tap. So, you’d give it +3v or -3v depending on whether you want it to go forwards or backwards. That way you’d only need 2 transistors for each motor rather than the 4 that would be needed for a full H-bridge.
the older version's 3.5 mm jack was to plug a dumper/trailer in, the dumper also had a 1.5 v D cell and when the trailer got the prompt from BigTrak it tipped out the load
That's a very interesting teardown, I've not seen that type of magnetic coupling before. These things were expensive when they came out, only one of my friends had one.
I had one back in 1979ish time frame. I also had the Big Trak Tansporter (trailer). I don't remember (that was a long time ago though) the transporter taking any batteries so the accessories port supplied the power for it. You could program it to lift to dump the cargo and then go back down. All of the transporters programming was don't through the big traks keypad.
I still have mine somewhere, christmas '80~ish, in it's polystyrene shell in the cardboard sleeve. It always struggled with the fibre lay on the lounge carpet, turned more one way than the other... I put a tray on top and programmed it to delivery sherry to Grandma!
Love it! I was 9 when the original came out, and was lucky enough to get a Big Trak and the Transport add-on for Christmas. I couldn't guess how many hours of fun I got it of it. When it eventually stopped working, I took it apart and marveled at the PCB and gear mechanisms. IIRC, the original could store 16 commands in memory. Did the newer one improve upon that? I certainly hope so! Also, IIRC the 9v battery only powered the lamp. Hopefully someone can correct me if I'm wrong.
I wish I had one of these when I was younger! I would have loved it! The closest I got was a little robot at school. I am pretty sure the new one can do more than 16 comments from my "extensive research" with it. It have a play and let you know!
Notice the complete lack of electrolytic capacitors and voltage regulators. 9V battery goes straight to the power pin of the TMS1000 processor. 6V rail off the bottom battery compartment is needed for the motors, the lamp and the speaker, it goes to the motor drive transistors and the high-current driver IC, misidentified as RAM in the video. The 3V centre-tap off the main battery goes to the other side of the motors. The motor drive transistors would pull their side of the motor to either 0V or 6V to make it run one way or another.
Perhaps someone has said it but what are the two power switch positions for either side of the off position. Mine they seem to just be the same? Anyone know?
I had one of the original US version of this toy as a kid (just an old guy now :P), and that port on top did provide power to an accessory called the transport. You can see it on the big trak webpage.
Great breakdown. I'm attempting follow a "build your own robot" article from a 1987 Boys' Life magazine that calls for two of these dual motor setups. I'm hoping I can find a place to source them. I could make it work with other motors, but I'm trying to stay true to the original.
I should mention that I have a Big Trak in my toy collection but I'd prefer to keep it in good condition and not scavenge parts from it. I could buy more on eBay, but I hate breaking down collectable toys if I can avoid it. But so far, no luck finding any motors on their own.
@Sasquatch - The MCU is a 4 bit TMS-1000, an example of the first commercial micro-controller released by TI in 1974. It is a Harvard design with 1K x 8bits of ROM for program storage and 64 x 4bits of RAM. Chips from the same family were used in many toys of the era, including Simon, Speak & Spell, Merlin and the Microvision. The electronics in the Big Trak have been reverse engineered at robotroom dot com (darn links) and the code running on the MCU has been dumped by Sean Riddle. HTH.
Anyone know a quick way to disable the sound on one of these. I've got a small fleet of them (think they're the replicas as they run 3 x D batteries). My school want to use them for Open Day, but the sound is way too much. Thanks in advance. (UK Computer Science teacher).
Yes, you get feed back when you press a button, when a program starts, stops and a nice sound to acompany the flashing light! I'll see if I can dig out a clip with the sound turned on and share a link!
In the reasearch for this episode, I think it was actually the very early versions that were grey, which were only released in the US. By the next revisions they went white. I think the US and International version had a slightly different keyboard too?
I've recently acquired both models and comparing them , The newer version drives and turns faster, This compromises accuracy because it rotates quicker and over rotates through momentum ( on lino). The older version drives/ turns slower and turns exactly on any surface. Great video guys.
Seems to me that if they are reading the motor rotation using the optical encoder they didn't really need the magnetic coupling they could have done a feedback loop in software.
I pondered this but my first thought was the coupling approach actually stops any deviation rather than correcting it so may give a straighter path. The other question is whether the TMS 1000 is up to the job...
Hello I'm new to your channel I really like watching my first episodekeep up the great work I wanted to know where can I get the 2010 model of big traka gain l enjoy my first episode watching your great show
If anyone is interested in knowing about the 1979 Big Track's brain (a 4-bit microcontroller!) or other electronics, there's details at www.robotroom.com/BigTrak.html
The second smaller chip in 1979 model is certainly not a RAM chip, it's DS75494, which is a 6-channel 150mA per channel driver. it is there to amplify the signal for the speaker and lamp and to drive the speed sensor LED.
The program only 16 commands in max length would have fit into 64-word RAM of the microcontroller. Since commands have a form of command type + command length where length is up to 99, i suppose they store command in one 4-bit word and length in two words, consuming 3/4th of the RAM. That and having the complete firmware fit into 1024 instruction words (8-bit) is some efficient programming.
One of my favorite toys as a kid. I even had the dump trailer. I'd spend so much time trying to create a programmed path from the kitchen to my bedroom.
I wanted to find a trailer for this too, but they seem to be really hard to find these days!
The Soviet Union made a clone of this in 1983, and I owned one! It was called "Луноход Электроника ИМ-11" in english --> MOON WALKER IM-11. To this day, I had NO IDEA that the Bigtrack had a trailor.....for all these years, we as kids in Soviet Russia could not find out what the extra hitch was for on the Bigtrack, 37 years later, I find out lol What an amazing piece of history, I would kill to own one of these today. Thank you so much for sharing this!
I had the 1979 version when I was a kid, I didn't know they remade it.
Really nice video - thank you! Presumably the centre tap on the old version simplified the motor drive circuit and the voltages applied to the motors are relative to the centre tap. So, you’d give it +3v or -3v depending on whether you want it to go forwards or backwards. That way you’d only need 2 transistors for each motor rather than the 4 that would be needed for a full H-bridge.
That's a really good point - I'm going to do a little follow up on the micro controller, I'll let you know if you are right!
the older version's 3.5 mm jack was to plug a dumper/trailer in, the dumper also had a 1.5 v D cell and when the trailer got the prompt from BigTrak it tipped out the load
That's a very interesting teardown, I've not seen that type of magnetic coupling before. These things were expensive when they came out, only one of my friends had one.
I had one back in 1979ish time frame. I also had the Big Trak Tansporter (trailer). I don't remember (that was a long time ago though) the transporter taking any batteries so the accessories port supplied the power for it. You could program it to lift to dump the cargo and then go back down. All of the transporters programming was don't through the big traks keypad.
I have so many memories of this, I really enjoyed this. Thanks David!
I enjoyed making it! Or breaking it, depending on which way you want to look at it!?
I still have mine somewhere, christmas '80~ish, in it's polystyrene shell in the cardboard sleeve. It always struggled with the fibre lay on the lounge carpet, turned more one way than the other... I put a tray on top and programmed it to delivery sherry to Grandma!
My grandmother would have approved!
Awesome. Do a Starbird next! I've always wanted to understand how the device knew, and reacted to, the ship's elevation/tilt to make different sounds.
it's a small tilt switch comprising a metal ball bearing that slides back and forth between some contacts.
Holy crap,it's about 1 cannon away from being the Mako.
I had one in 1979. Great toy, probably cutting edge technology then. 2010 version is more of a nostalgic nod to its older brother.
Superb job! Thank you so much!
The original circuit with the TMS 1000 4bit processor is shown on www.robotroom.com/BigTrak.html
Love it! I was 9 when the original came out, and was lucky enough to get a Big Trak and the Transport add-on for Christmas. I couldn't guess how many hours of fun I got it of it. When it eventually stopped working, I took it apart and marveled at the PCB and gear mechanisms.
IIRC, the original could store 16 commands in memory. Did the newer one improve upon that? I certainly hope so!
Also, IIRC the 9v battery only powered the lamp. Hopefully someone can correct me if I'm wrong.
I wish I had one of these when I was younger! I would have loved it! The closest I got was a little robot at school. I am pretty sure the new one can do more than 16 comments from my "extensive research" with it. It have a play and let you know!
Notice the complete lack of electrolytic capacitors and voltage regulators. 9V battery goes straight to the power pin of the TMS1000 processor. 6V rail off the bottom battery compartment is needed for the motors, the lamp and the speaker, it goes to the motor drive transistors and the high-current driver IC, misidentified as RAM in the video. The 3V centre-tap off the main battery goes to the other side of the motors. The motor drive transistors would pull their side of the motor to either 0V or 6V to make it run one way or another.
Perhaps someone has said it but what are the two power switch positions for either side of the off position. Mine they seem to just be the same? Anyone know?
Dude, I had that toy!!!!!
Me too!!! It was the first toy I tried to fix When I broke the axel I was 10yrs old and used tape
@@jcougar831 front axel? I may have also found that issue with some help from a 4 year old...
I had one of the original US version of this toy as a kid (just an old guy now :P), and that port on top did provide power to an accessory called the transport. You can see it on the big trak webpage.
Great breakdown. I'm attempting follow a "build your own robot" article from a 1987 Boys' Life magazine that calls for two of these dual motor setups. I'm hoping I can find a place to source them. I could make it work with other motors, but I'm trying to stay true to the original.
I should mention that I have a Big Trak in my toy collection but I'd prefer to keep it in good condition and not scavenge parts from it. I could buy more on eBay, but I hate breaking down collectable toys if I can avoid it. But so far, no luck finding any motors on their own.
Was hoping you'd go into more detail on the TI chip and how it functioned.
I still can, do you have specific questions or are you just after an overview?
A thorough overview would be great - a how it works/what it does/how it addresses the small memory etc.- thanks :-)
@@TheRealSasquatch I'll see what I can dig out for you!
@Sasquatch - The MCU is a 4 bit TMS-1000, an example of the first commercial micro-controller released by TI in 1974. It is a Harvard design with 1K x 8bits of ROM for program storage and 64 x 4bits of RAM. Chips from the same family were used in many toys of the era, including Simon, Speak & Spell, Merlin and the Microvision. The electronics in the Big Trak have been reverse engineered at robotroom dot com (darn links) and the code running on the MCU has been dumped by Sean Riddle. HTH.
Anyone know a quick way to disable the sound on one of these. I've got a small fleet of them (think they're the replicas as they run 3 x D batteries). My school want to use them for Open Day, but the sound is way too much. Thanks in advance. (UK Computer Science teacher).
I can tell you for sure that the 1979 version WAS innacurate with the turns, interesting to learn why. :D
I'd imagine that even if the wheels were turning, they might be slipping on the surface with that design.
Did you say buildability?
What was the speaker used for, did this thing play sounds or music? I've never owned one of these but I had a corvette that did the same.
Yes, you get feed back when you press a button, when a program starts, stops and a nice sound to acompany the flashing light! I'll see if I can dig out a clip with the sound turned on and share a link!
Hey you should do a teardown for a inkjet printer. All the paper management system should be fun. An old vs new would be even better!!
I thought a 3 way comparison, dot matrix, ink jet and laser would be good? I'd have to prepare to get covered in ink and toner!
@@a531016 even better!!
@@a531016 hey! Just wanted to check if the printer teardown still expected in future. BTW, love the show, the recent projector teardown was legendary.
@@ujjawalaggarwal9985 Thanks! Let's just say there is an episode in the queue that you'll enjoy a lot!
Why s the British version White and the USA version Grey?
In the reasearch for this episode, I think it was actually the very early versions that were grey, which were only released in the US. By the next revisions they went white. I think the US and International version had a slightly different keyboard too?
@@a531016 Yep, I had the early US grey version along with the transporter.
I wonder if there's a smaller toy car that works on a few AA batteries and that are programable.
yep bigtrak jr and bigtrak rover.
Did the Usbourne computer books have an interface project to join the big track to C64s or Spectrums.
I didn't know that!? Do you have any information about it or idea how it worked?
I've recently acquired both models and comparing them , The newer version drives and turns faster, This compromises accuracy because it rotates quicker and over rotates through momentum ( on lino).
The older version drives/ turns slower and turns exactly on any surface.
Great video guys.
Do the sounds sound alike?
@@jcougar831 yes they do.
Seems to me that if they are reading the motor rotation using the optical encoder they didn't really need the magnetic coupling they could have done a feedback loop in software.
Daniel Bull In 79 ? It's the cheapest way even today.
I pondered this but my first thought was the coupling approach actually stops any deviation rather than correcting it so may give a straighter path. The other question is whether the TMS 1000 is up to the job...
Hello I'm new to your channel I really like watching my first episodekeep up the great work I wanted to know where can I get the 2010 model of big traka gain l enjoy my first episode watching your great show
If anyone is interested in knowing about the 1979 Big Track's brain (a 4-bit microcontroller!) or other electronics, there's details at www.robotroom.com/BigTrak.html
how can u tell them apart if u see them in a shop window ?
The original one has a sticker on both sides near front with the letters MB on it, (thats allowing stickers haven't come off)
How would you tear a 2010 version down so the plastic can be de-yellowed with hydrogen peroxide? thank you
You skipped over the bit when you got the single screw out the back behind the grey bit
I just threw one of these away. It was a PITA to get to stay working.
Original or modern? What was the problem/s?
I need a new membrane keyboard. I can’t get it to send any commands. No beeps.
Needed an overhead light for this video very hard to see.
Yes, apologies, black gears and black plastic boxes weren't a good combination!
Through-hole, just the way I like it.
Always wanted one of this, now I can do one for myself with little more than an Arduino and several resistors... 🤓
Go for it! They are great fun! What form would you design?
Dude, slow down in your presentation!
Didn't know they brought it back! Got to get one
I loved this toy so much I bought 2 of my friends tanks cause the dam wheels broke so easily