• Author Author: kmikemoo
  • Date Created: Date Created
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Choo Choo Go Stick

Table of contents

Choo Choo Go Stick

Abstract

Modify battery operated Christmas train engine so my 4 year old grandson can make it go and stop - all by himself.

For many of us, there is a magical bond between Christmas and toy trains. One of the few déjà vu moments in my life was about a train set that I received for Christmas one year. My Dad got a Christmas train quite late in life – and was never able to part with it, even when he stopped decorating for Christmas. Looking back, it was probably something that he had wanted as a child - but he grew up dirt poor. And then he was too grown up for a kids toy. I'm glad that he finally got his train before he passed.

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I wanted my grandkids to experience the magic of a Christmas train – so I bought one – before Dad passed – because he wasn't going to part with his. I asked – and got the Grumpy Cat look as my reply.  Hey!  Okay!  I crossed the line. Laughing  My train isn't as cool, but mine has a movie theme. Joy

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You know... the only problem with most of these trains is they are either ON or OFF. Sure there are model railroad sets, but you don't hand one of those over to a four year old. Or a six year old.
So the kids either just get to watch – BOO! No fun there. OR... you use the kind pictured above and you're trying to put an engine on the tracks while it's running – and then attach some cars. It's painful to watch – or participate in.

What? Put it on the track and then flip the switch?

GREAT PLAN! Have you ever tried that in real life with a small child?  Even the older kids struggle.

Herein is the basis for my project. Add a Start/Stop switch to the affordable battery powered Christmas train that a small child can operate – with the train already on the tracks. And it needs to be minimally invasive so the Christmas train still looks like a train and not scrap wire on wheels. And it needs to run on 3VDC – since the train is powered by two D-cell batteries.

My initial circuit plan was to use a capacitive touch switch. Space is very limited within the train so I was trying not to go the “microcontroller and relay” route.  While looking for a way to integrate the capacitive switch, I stumbled on a latching switch module based on the MEM2313 P-channel MOSFET.  The capacitive modules that I have go high when touched and this module is momentary active low.  PERFECT!  Plan B!
If you watched the video, you already know that I went with magnetic reed switches - but to a small child... THEY are in control.  How it is achieved is immaterial - to them.

BEFORE
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Pretty simple.  Flip the switch and it runs.

DURING
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Parallel magnetic reed switches hot glued into the corners of the cab.

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The control module.  Dime added for scale.  And its wiring diagram below.

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FINISH PROJECT

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A few extra wires but still clean.

NEW SCHEMATIC

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I added the diode for circuit protection.  When the grandson pushes the engine across the floor, it doesn't matter that the switch is OFF.  The light still lights - because the motor is also a permanent magnet generator.
And sometimes... everything with wheels is a Matchbox car.

CONCLUSION

I'm happy with the outcome but even more so with the shift to the magnetic switches.  Whether it's a wand or a whacking stick, every kid gets a giggle out of smacking a moving toy.  It's even more magical if it starts or stops doing something because of it.  Think of it as entry level training for percussive adjustment repair techniques.  For most of this train's life, it has been running into Hot Wheels, Matchbox cars, it's own cars... I don't think whacking it with a magnet on a popsicle stick is going to faze it.
Merry Christmas.  Happy holidays.  Happy New Year! Relaxed

Attachments

References

Switch Module:  https://www.amazon.com/dp/B07NYQRWSZ?ref=ppx_yo2ov_dt_b_fed_asin_title

Category : project
  • in reply to colporteur

      Relaxed  I immediately checked mine out.  Thumbsdown  No selection jumper on the boards I have.  Mine also uses the TTP223B chip. I would have to use some bodge wires to make it work.
    Credit to the e14 Community - I actually read the chip datasheet to figure out what it would take to do it.  ThumbsupJoy

    I originally bought the touch sensors for an iambic morse code "key".  Cool in concept.  Poor in execution.  The side of the index finger just wouldn't reliably activate the touch sensor - so... operator error.  I'm sure that I'll find a use for the sensors (maybe). Laughing

  • in reply to kmikemoo

    I've experienced your "quality decisions" dilemma and defining best:) I've also ran the gambit of needing a HIGH but having a LOW. 

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    I've also used capactive touch switches. I recently discovered the A & B jumper on these devices, I bought a few years ago, allow me to change the output. Who knew:)

  • in reply to colporteur

     Great question.  I suppose I just took the path that I understood.  I wanted to use the capacitive touch switches I already had - but output was only active when touched.  So I needed a latching device - that would work on 3VDC - in a small space.  I found one that could be delivered just after Christmas - while the grandkids and I were still on holiday break/vacation.  What does it take to make that device work?  Active low, not active high like the touch sensors.  Out they go.  What will work?
    I look back at projects like these and laugh at my "quality decisions".  Was it the best decision?  Ah... maybe?  Like some, I can suffer from analysis paralysis.  This path got the project built. Relaxed

  • K, I loved your story and project. Why the need for the latching switch module? I think I was making rather merry and miss something in the explanation.

    Replacing the manual switch with the reed-switch would result in the same. Oh wait, maybe your reed switches don't latch! I've seen latching ones.

  • Well done,. The elegance of simplicity deserves more kudos than are usually attributed. 

  • Perfect.

    A funny true story..  

    About 10 years ago, my colleague in our robot club built an ugly cheapo rc robot on a corrugated plastic sheet. There were 2 continous servos tyrapped under the corrugated sheet for motion, and another servo tyrapped to the top which he attached a meat tenderizer hammer. He glued a rubber duck on top. He showed that as a demo as part of our robotics program at a local scifi convention. It was the hit of the show, all the kids loved it, and fought to get a turn driving it, and chasing things with the hammer. We joked that everyone needs an rc rubber duck with a hammer.

    Whacking stuff rules. 

  • in reply to beacon_dave

    Laughing  I like it, but - truth be told - our attention spans aren't that long.  As to stopping the train before it hits an object on the track... we're not that mature. Joy
    And now you know the real reason why we don't use my HO train set. Relaxed

  • Another great idea.

    You could perhaps shape the popsicle stick to resemble a station master's despatch baton.

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    And just when you thought you were done... new despatch batons appear to have interactive LEDs built into them Slight smile

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    Another idea might be to have some moveable objects that can stop, pause, reverse the train when encountered on the track to allow a bit more interactivity. e.g. a cow or car on the line brings the train to a halt until it is removed.