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$5 Line Follower Fun - Page 2 — Parallax Forums

$5 Line Follower Fun



  • And it's working!

    One transistor was installed backwards. While the bot looks like everything is mirror-imaged (the LEDs are), both transistors face the same way.
  • ercoerco Posts: 19,925
    Perfect! Glad to hear that. Another satisfied customer. :)
  • It's the first time I've assembled a kit with no instructions. Technically, there were instructions, but a blurry photocopy in Chinese doesn't work for me.
  • ercoerco Posts: 19,925
    It's amazing that these kits have been around for a long time, yet Ebay sellers and Banggood just say "no English instructions". If you surf around, you can find plenty of photos of the finished item. IMO the only tricky part is mounting the phototransistors and illuminating LEDs, since they are just hanging down and need to be almost scraping on the ground. Maintaining alignment is very important for calibration, but these are easily bent (and/or pads broken off) in a collision when they go off course. I think the kit should include a simple front bumper to hang off the front skid bolt.
  • Erco - No need to cut the trace when you've got an extra socket laying around.
  • ercoerco Posts: 19,925
    Another way to skin that cat! Did you get it working? Simple circuit mod but the pot adjustment is trickier than stock.
  • I didn't need to adjust anything, it just ran better.
  • ercoerco Posts: 19,925
  • ercoerco Posts: 19,925
    I enjoyed watching these Russian kids building their line follower kits. They're getting the jump on American kids, who are all dancing!

  • ercoerco Posts: 19,925
    edited 2017-06-20 01:32
    Just got my July SERVO print magazine, where I describe several non-programming robots including these $5 line followers in the Ask Mr. Roboto column:

    The article looks good IMO, editor Robin does a great job on the layout and is super easy to work with. Once again, I encourage everyone here to submit an article for print publication. SERVO is a robot magazine, and the only game in town now that ROBOT magazine is gone. Hopefully it will survive and thrive for a while, but there are no guarantees. So right now. WRITE NOW!

    Several forumistas have written for SERVO: Carol Hazlett, Bill Henning, Geo Leeman, Chris Savage, to name a few. It's a nice way to "give back" and get paid to help fund your future projects. Just get in the habit of taking photos and documenting your projects along the way. So much easier than taking your bot apart afterwards to take internal detail photos and trying to remember the tricky parts.

    The editors are wide open to subject matter, most anything of general interest. Tech articles, tutorials, construction tips, combat weapons, product reviews, whatever. Check out the writer's guidelines at and get crackin'! Tell 'em Mr. Roboto sent you.

  • ercoerco Posts: 19,925
    edited 2017-06-27 22:13
    Simple mods allow these $5 line followers to track towards light. Two different implementations shown.

  • ercoerco Posts: 19,925
    edited 2018-04-05 02:07
    I just had to be the first kid on the block to have this stealthy line follower jet, even though it costs $10. I'll really soup it up for max speed.

  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2018-04-05 04:57
    Looks like it uses those nice narrow tires. Wish they sold just those (and the gearbox motor). Everyone sells the weakling motors with the fat tires, and those robots have terrible steering problems. The narrow tires are better.
  • Heater.Heater. Posts: 21,233
    What, analog control, no MCU?
  • ercoerco Posts: 19,925
    Where ya been. Heater? LM393. Analog. Old skul.
  • Heater.Heater. Posts: 21,233
    Bah, kids and their new fangled op-amps.

  • Aren't the 'tires' just O-rings? There are cheap O-ring kits on Ebay and other places. Of course, that doesn't help with the gearbox and motor supply issue. :)
  • ceptimus wrote: »
    Aren't the 'tires' just O-rings?

    O-rings mounted on a wheel. The wheel has the proper molded double-D shaft hole, for specific use with the gearmotors. These wheels are not nearly as widely available as the wide-track tires normally sold with these motors.

  • ercoerco Posts: 19,925
    The LFR kits with gearmotor modules use foam tape for assembly. Simple and quick but it just falls off after a month or so, and the sticky mess is hard to clean up and repair. I'm not normally a fan of worm gears, but these alternative kits (same price, as low as $4) work great and will last much longer if properly assembled.

  • ercoerco Posts: 19,925
    Uh... strike that, reverse it.

    Free coasting (no binding) may be efficient, but it stops these $4 worm drive LFRs from following the line! Live & learn.

  • ercoerco Posts: 19,925
    Down to $3.44 now! How low can they go???!!! Time to build a swarm of line followers!

  • ercoerco Posts: 19,925
    Mini treaded line followers, $5 for one, or $7.50 for two.

    Act fast, ad says only 3 items and 3 hours left!

  • ercoerco Posts: 19,925
    edited 2018-06-10 04:06
    These li'l dudes arrived today and work great. They really hug the line and acquire it easily. I was about to make a video, but turns out there are plenty already. Comes with 4 watch batteries installed.

  • ercoerco Posts: 19,925
    Building & tweaking some of these cheap analog Line Following Robots for an upcoming Maker Faire. I can't believe how popular these were last time, I plan to give some away at the Faire.

  • ercoerco Posts: 19,925
    edited 2019-11-02 16:12
    Under $4 for the first time in a while. $3.29 for 4+, but that's hoardin'. :)

    Stocking stuffers for budding roboticists? "Tis the season all too soon.

    Edit: I just noticed this is a new version of the chassis PCB. It uses metal brackets to hold the gearmotors, and there is a third LED in the center of the board. Hmmm...
    800 x 800 - 39K
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