Help wanted: RoboPaint

James “techninja” Todd writes that a few more hands might be helpful on the RoboPaint project:

RoboPaint is an open source app for controlling painting/drawing robots, made for my daughter’s award winning Open Source WaterColorBot! The project is taking off with lots of users and lots of great features, and is all written in web standards node-webkit to run on all operating systems.

Interested? Sign up to help out at


Three Fives in IEEE Spectrum


Our Three Fives Kit was featured in this month’s IEEE Spectrum. From the article:

Just as DNA models, star maps, and periodic tables serve as reminders of fundamentals that can get obscured by day-to-day minutiae, so too the Three Fives kit is a reminder that even the most complex digital processor is still at its heart just a collection of very simple components.

You can read the full article and see pictures of it in use in a sample circuit over at IEEE Spectrum.

Basics: AVR Target Boards and Arduino Compatibility

Gary writes:

I have fallen in love with your Diavolinos – thank you!
My question: does the “Simple target board” allow for the 6-pin FTDI Friend hookup to upload sketches? This is quick and easy with the Diavolino. I’m new to reading circuits and stuff, and I cannot tell looking at the target board. It says to use in-system programmer, but I prefer to not buy another interface. Thanks!

Excellent question! It is certainly possible, but not as quick and easy.  Both the Diavolino and our ATmegaXX8 target boards boards use the same chip, usually the ATmega328P.  But, one might say that our ATmegaXX8 board is a simple AVR target board optimized for use with an AVR ISP programmer (like the USBtinyISP), whereas the Diavolino is a simple target board optimized for use with the FTDI interface.

XX8 Target Board

Versus a “bare” target board (with just the chip and power), there are four things that you would normally add, in order to use the FTDI interface to upload a sketch from within the Arduino environment:

Continue reading

Larson Scanner modding


Anton wrote in to ask:

I want to purchase your Larson Scanner kit but need to be able to run it from household current … is there a converter that you would recommend?

Since the Larson Scanner normally runs from 3 V DC, a regulated 3 V power supply can be hooked up in place of the 2xAA battery box. However, 5 V power supplies (like this one) are much more common, and the circuit can be run from 5 V with only minor changes. if you replace the nine 16 ohm resistors in the Larson Scanner kit with 120 – 150 ohm resistors, you can power it from 5 V directly.

Another related question we occasionally get is how to run the Larson Scanner with green LEDs. (Note: by green, we mean “pure” green LEDs which have a forward voltage of about 3 V. Older style yellow-green LEDs with a forward voltage of ~2 V can be used as drop-in replacements for the red ones.) 

If running off of battery will work for you, this is an even simpler change: merely replace the 3 V battery holder with a 4.5 V one, such as a 3xAA. It is a happy coincidence that the circuit can run with red LEDs at 3 V or green LEDs at 4.5 V using the same 16 ohm resistor value. So how about running a green Larson Scanner from a 5 V power supply? Replace the nine 16 ohm resistors with 39 ohm resistors and you should be good to go.

You can find the documentation for the Larson Scanner and more stories about modding it on our wiki. We’d love to hear about any mods you do to the Larson Scanner in the comments or see pictures in the flickr pool.

Evil Mad Scientist Laboratories Valentine Projects

LOLHearts - 34

We’ve rounded up our Valentine projects for your last minute preparations:

If one of our projects inspires you make something, we would love to hear about it in the comments or see photos in the flickr pool!