Snap-O-Lantern Kit

Just in time for Halloween, we’re launching a Snap-O-Lantern kit. You can still build this robotic snapping pumpkin from scratch using our original instructions, or you can do it the easy way with this kit, which uses one of our ATtiny2313 target boards and has all the parts you’ll need— except the mini-pumpkin and three AA batteries.

We’re putting the full documentation for the kit on our wiki.

Maniacal Labs on the Three Fives Kit

Dan at Maniacal Labs posted a review of our Three Fives kit:

… yay for creative kits that cause you to go out and (re)learn stuff! The cool thing about the 555 chip is that it is very much a building block to bigger things. There are plenty of resources out there for 555 applications and project ideas. I’d like to thank Eric Schlaepfer for his awesome kit idea and Evil Mad Scientist for helping make it available to the masses!


LED Vertical Blinds

dinofizz posted in the forums about the LED display based on the Peggy 2 he installed on his vertical blinds:

I had custom PCBs made to help daisy chain the vertical blinds (they’re sitting on top of the horizontal beam from which the blinds hang). 300 ft spool of 16-way ribbon cable completely used up. Around ~4000 individual solder joints, and I’m still using breadboard to hold things together at the moment! Took me forever.

He linked to a few more build photos over in the forum post, and he even posted some video of it in action:

In-circuit emulator for the 555

555- ICE

After building up one of our Three Fives kits, Ed wrote in to say:

I have been an electronics hobby enthusiast for well over 45 years building many, many kits, hacking my own stuff, others’ stuff, designing projects, etc.  I have to say, your Three-Fives kit is truly the nicest commercially available kit I have ever had the privilege of assembling.

I was inspired to create a small, flexible wire harness with an 8-pin header on the end to effectively create an “In-Circuit Emulator” interface.  You can prototype a circuit and then quickly pull the chip and insert the “ICE probe” and use a scope to probe any part of the chip you want to see what’s going on “under the hood.”

Thanks to Ed for sharing his project with us— and what a cool idea!

Basics: Base Resistors on Transistors


Our reader Jon wrote in with a question about our open collector tutorial:

I really appreciated the tutorial, and I was able to follow along and understand it very well. One question I had was – what is the purpose of the 1 kilo-ohm resistor that is connected to the base of the PNP transistor? Because when the open collector is ‘high’ then the base of the transistor is at 12 V and it appears the 1 kohm resistor didn’t affect anything, and then when the open collector goes ‘low’ then the base is connected to ground through the output of the SN7407. So basically, what would the difference be if there was no 1 kilo-ohm resistor at all?

And, that’s actually an excellent question, about something that we usually gloss over.

The short answer is that this is a “base resistor” that we use to limit the maximum current that flows through the base of the PNP transistor.  But, let’s take a look in a little more detail, and see what would happen if we didn’t have that there.

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