Turbot Is A Beam/Picaxe Hybrid

[James] wanted to build a BEAM turbot. He ran into some problems with the BEAM circuitry though, and ended up with a BEAM/Picaxe hybrid.
Beam robotics
are the brainchild of Mark Tilden. The acronym stands for Biology, Electronics, Aesthetics, and Mechanics. BEAM based bots were very popular with hobbyists in the 90’s and early 2000’s, but popularity has since died down. BEAM robots tend not to use microcontrollers, instead attempting to simplify things down to the lowest number of elements.

[James’] turbot uses a miller solar engine. The original design used the engine to drive a Solar Turbot Latch. [James’] problem was that the photodiode “eyes” of the robot were not properly enabling the 74AC245 to pass current to the motor. Since the robot was built in a tiny space, debugging the circuit was extremely hard. After struggling with the ‘245 for some time, [James] decided to swich out the BEAM circuit for a Picaxe microcontroller.

The Picaxe can only sink or source about 20ma per pin, which is slightly less than the no load current of [James’] motors. To make up for this, he ganged up four pins per motor. There was some risk in the motors blowing up the Picaxe. However between the lightly loaded gearmotors and low current solar panels it seems to be working just fine.  Overall the bot is a very clean, compact build. Jump past the break to check out its really smooth crablike walking action.

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PICAXE Using LEDs To Communicate

[Relwin] has being working on using LEDs as bi-directional devices. The setup above allows him to use each LED as an input, looking for a bright light source and then syncing up with the activity it receives. It is the most basic of communications using the components. The hardware at the heart of the system is a PICAXE development board on the left. The blinking light to the right causes the LED on the left of the picture to blink, but moving the blinking source over to that side will reverse the effect. The chip is programmed to play a tune on a piezo buzzer whenever a connection is lost. What is interesting to us is that these green LEDs will not detect a red LED flashing because the voltage threshold is different on the detector side of things.

He’s got some code available, but we’re really looking for the ideas of what to do with this concept. Maybe something along the lines of LED matrix video puzzles, or a variation on this laser-pointer LED game. Watch the demo video after the break and then let us know what you would use it for by leaving a comment.

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PicAxe LEGO Tank

[TomTheGeek] built a LEGO tank with a PicAxe controller. Locomotion is supplied by a Lego Power Function motor controller. He cut an LPF extension wire in half so that he could patch into the PWM signals without altering the motors themselves. You can make out the control circuitry and a small breadboard in the tank’s turret. [Tom] added a laser pointer to the tip of the barrel but we’d like to see an IR LED. The tank is controlled by a infrared remote control and adding TV-b-gone functionality to the toy would create something of a Rube Goldberg feature for turning off the tube. But alas, there’s no programming space left for that as the PicAxe 08M is limited to 256 bytes.

There’s a video after the break of this little demon tracking its way around the room. This is a nice addition to the other LEGO tank we saw a while back.

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Picaxe Tachometer


It might seem like we’re on a vehicle hacking kick this weekend, but [Rex] built an excellent custom digital tach for his race car. It uses the classic seven segment displays, a PICAXE microcontroller and works with most engines. He’s released full source and PC board designs to boot. This looks like a great little tachometer project for you microcontoller fiends out there.

BEAM Dragonfly Causes A Flap

Normal people throw away stuff when it breaks. But not people like us. Or, apparently, [NanoRobotGeek]. A cheap robotic dragonfly died, and he cannibalized it for robot parts. But he kept the gearbox hoping to build a new dragonfly and, using some brass rod, he did just that.

The dragonfly’s circuitry uses a solar panel for power and a couple of flashing LEDs. This is a BEAM robot, so not a microcontroller in sight. You can see a brief video of how the dragonfly moves.

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Random Word Pairings Mark The Time On This Unusual Clock

Gosh, the fun we had when digital calculators became affordable enough that mere grade school students could bring one to class. The discovery that the numbers could be construed as the letters of various dirty words when viewed upside down was the source of endless mirth. They were simpler times.

This four-letter-word “clock” aims to recreate that whimsical time a bit, except with full control over the seven-segment displays and no need to look at it upside down. This descends from a word clock [WhiskeyTangoHotel] made previously and relies on a library of over 1000 four-letter words that can be reasonably displayed using seven-segment displays, most of them SFW but some mildly not. A PICAXE is used to select two of the four-letter words to display every second or so, making this a clock only by the loosest of definitions. Word selection is pseudorandom, seeded by noise from a floating ADC pin, but some of the word pairings in the video below seem to belie a non-random sense of humor. As is, there are over a million pairings possible; it might be fun to add in the full set of two- and three-letter words as well and see what sort of merriment ensues.

While we like the Back to the Future vibe here, we’ve seen some other really nice word clocks lately. There was the one that used PCBs as the mask for the characters, and then a rear-projection word clock that really looks great.

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Making PCBs With A Cutting Plotter

[LudwigLabs] is creating PCBs using copper foil and a cutting plotter (vinyl cutter). In this approach, it’s an additive process where instead of removing copper from a copper-clad board, the traces are cut out of copper foil and transferred to a solid backing surface (cardboard, fiberglass, etc.).

While similar to the use of copper tape laid out by hand, as covered by us last year, the big advantage of using a cutting plotter is that it allows one to create much more complicated traces similar to those you would expect to see on a factory-made PCB. Since cutting plotters translate a 2D design into very precise movements of the cutting blade, this allows for sharp angles and significantly thinner traces, allows designs from EDA software like KiCad or Altium to be quickly translated to physical boards.

Enterprising hackers might consider the possibility of using this approach to make two-sided, and even multi-layered boards. The copper is produced separately from the substrate which opens up the potential for using uncommon materials like glass or paper to host the circuits. The main limitations are the transferring of (very delicate) copper structures and creating vias without damaging the traces.

As a comparison with traditional PCB fab processes, the photo exposure and etching (or laser exposure and etching) process requires the creation of masks, UV exposing a board, etching, cleaning and so on. The simplicity of copper foil traces has led to many experimenting with this approach. Would you want to use this additive process, or are there refinements or alterations you would make?