light tracking function? I found several videos such at
which — at best — demonstrate random motion.
After testing mine, I realized that the circuit makes the
robot want to turn towards the dark and stop, which is
pointless and futile — not to mention just the opposite of
the website claim. I swapped the motor wires left and
right, and aimed the LDRs forward and down (Figure 10).
Suddenly, the robot came to life and began tracking
towards a flashlight beam. It is squirrely fast and a handful
to steer, but quite fun. Check it out at
Those two little tweaks made all the difference in the
world, but most people may never know about them. That
really annoys me. It’s as if no one at RadioShack ever cared
enough to build and test this item. Did they not get
Another haphazard element in the instructions is that
it gives you a choice of how to mount the two front LEDs:
flush and pointing up as I did; or hanging out front like
bug antennae. They are right in the crash zone, and also
right where they can potentially be seen by the photocells.
In that configuration, every crash probably moves the LEDs
and varies their effects on the photocells, introducing
random control factors.
This is ROBOTICS, this is SCIENCE, darnit! THIS is why
the Shack closed down. Well, at least you and I know how
to fix this item’s shortcomings. (Sorry, I didn’t mean to get
off on a rant.)
I will miss the Shack for sure. I’ve spent lots of time
and money there. It was a great standard resource for
builders and makers to specify commonly-available parts, so
it just got harder for the DIY crowd to get parts locally.
Plan to stock up on robot parts for future builds!
Well that’s all we have time for. I hope this info was
helpful. Even the simple robots mentioned here can be lots
of fun and very educational. Best of luck sparking interest
in today’s youth! They will be the roboticists of tomorrow.
Don’t forget! If you or they have more questions, send
them to me at firstname.lastname@example.org. See you next
12 SERVO 07.2017