Thermo-Bot 1.0

A phototropic bicore-tank mobile BEAM robot, that turns away from a heat source.


Thermo bot uses a bicore tank circuit with some modifications and additional features like my other bot named Rovore, created by our very own Wilf Rigter. But this time, it's a smaller version and without a solar panel. This bot, at first (when turned ON), seeks and goes towards a light source (phototropic). When it's under a light source or a lamp, it just wander around it, just like a common photovore. The cool thing about this bot is, when it detects or senses  heat, this bot changes its mode and will  become photophobic. While in photophobic mode, this bot will turn away and will go to any dark area it could find and stops there to cool itself. The reason why this bot stops in a dark place when it tries to cool itself because, it has a light-activated switch built-in. Anyways, when thermo bot cools down, it will resume to go to a light source again, being phototropic. The cycle repeats.

Another important features of  this bot is that, it  has bump or tactile sensors to avoid obstacles. It also have IR pairs as edge sensors (left and right), to avoid falling from any corner of a surface. One thing more is that, it also has a low-voltage alarm circuit. When its battery voltage reaches down to 3.5 volts (set trigger point, can vary), it will sound a ringing phone tone. I just got this very small ringing tone circuit in a greeting card (when you open the card, it rings). But you can also use any beeping device or even a blinking LED as an indicator. Use the classic LM3909 blinker/flasher circuit instead.

There's also a charging socket behind the bot. I use a cellphone charger to charge the battery. As always, I use cellphone batteries for my bots because it's thin, light-weight and has enough current to run most of the BEAM robots you can think of. But make sure you use a proper and a recommended charger for it, or else you may damage your battery. And lastly, thermo bot has dark-sensing circuit that flashes 2 blinking LED's (red and green) when it's in a dark place.

So here we go...

Quick Info:

Sensors - 1 thermistor (heat-sensing), 2 tactiles, 2 IR pair edge sensors,  1 dark sensing-circuit, 1 light-activated switch and a low-voltage alarm

Length - about 3 1/2  inches (not including the whiskers)

Width - 2 inches

Height - almost 2 inches (including the elevated thermistor)

Power Supply - 3.7 volts / 900mA Nokia cellphone battery

Low-voltage alarm trip point - 3.5 volts (depends on the battery you use)

Motors - 2 micro servos (modified for continues rotation)


It's much better if you use a 9 volts battery or equivalent and use a 5 volts voltage regulator like LM7805 to run the L293D IC chip. 5 volts goes to pin 16 (Vcc) and 9 volts goes to pin 8 (Vmotor) of the L293D chip, as a rule.

Space Games:

Robots have been featured in TV, sci-fi films, space games, books and comics for many years now. A main character of a story or game may have a robot to assist him with specific tasks or the robot may even be the main character. These space games and stories have been an inspiration for many of the robots being built today that assist with several tasks from cleaning, to cooking, and even assisting in medical offices.

Bicore Tank Circuit

by: Wilf

Thermo-Bot 1.0 Add-on Circuits

(under construction)

Image Gallery

(click any image to enlarge)


Finished Product




You may have noticed that I've removed the "outer" belt drive tracks and reuse the original rubber wheels. This is because the outer belt drive slips and removes most of the time when this bot runs. I can't find any smaller size for the outer belt. However, the "inner" belt drive remains and still helps to run the 2 small pulley wheels, making it a 4-wheeler bot. But if I could find a perfect size for the "outer" belt drive, it's much better. I'll just show you the two driving configurations in the video clip section as soon as I finish making them. Relax and enjoy!


Newly added pics!



The 3 new images above is now the final and latest design. I've used the other version of the  bicore tank circuit and it works just fine. I've also replace the rubber wheels with rubber belt drives. It moves well and runs like a tank. Much better looking isn't it? 

Well, the wirings under the pcb are messy and it's like a "punishment" when I re-wired all of it, I mean ALL OF IT! I've used wire-wrap type of wires (very thin solid wires with different colors) to make the jumpers. I don't recommend  you to do this type of work (jumper wirings) unless of course you know what you're doing. Well, I'm used to it and it's fun for me now. Cheers everyone!

Video Clips


Heat-sensing - 16.9 MB - this one is kind of strange, I didn't expect some behaviors of this bot, but looks cool though.

                                      - notice how it parks itself to a shadow away from the light, it reverses and stops. It's like it has a mind of its own.

Edge-sensing - 10 MB - avoiding an edge of an elevated surface.

Light-sensing - 3.81 MB - a classic demo, following a flashlight.

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Copyright 2007  by Harold R. Ilano. All Rights Reserved.

BEAM Patents by Mark W. Tilden.

Visitors since June 2, 2007