Pneumatic Toe Pincher Coffin, Part 3

The 4th quality skeleton arrived from skeletonstore.com wrapped in bubble wrap. The "skeleton wrapped in plastic" look alone would make a scary prop. I left it on the dining table as a centerpiece for a few weeks while working on the coffin.

The skeleton needs to be prepared before use. Some joints need adjusting, bolts tightened, etc. I also spent a day filing down all the flashing with a Dremel Stylus Cordless Rotary Tool- it doesn't have to be perfect, but you can spend a few hours removing excess material from the chest, arms and hands.

The entire skeleton is then painted with Rosco white fluorescent paint. In retrospect white fluorescent spray paintwould have been faster.

The bucky skeleton goes in the coffin with the feet resting on the 1/4" plywood panel covering the footwell where all the pneumatics are hidden. I mounted a four foot UV fluorescent fixture to the base up against one of the side panels - although not perfect the lighting is sufficient.


On to the "scream" sound effect when the lid opens. For several years I have used Radio Shack's "sound recording and playback module" in various props and wanted to find something better. Ideally, less components. The Radio Shack module requires a 9-volt battery and isn't easily interfaced to an external speaker. I had to carefully solder wires onto the circuit board and run them to an amplified speaker, which required another 9-volt battery.

Blue Point Engineering makes a large selection of audio boards and amplifiers but I could not find a simple one channel board that also included an amplifier. While surfing smarthome.com I came across the ELK-120 which cost less than a BPE sound board and also included a 24-watt amplifier. Even better, the board can start playing an audio channel as soon as 12vdc is applied to the appropriate terminals. This cut complexity down to 3 components, none requiring batteries: Board, speaker, and power supply.

I encourage you to save all your power supplies/transformers/adapters. Even if you have upgraded your cell phone, don't throw the old cell phone charger away if it can provide a useful output - anything DC is worth saving for these kinds of hobby projects. Laptop power supplies are a goldmine. You can probably find buckets full of them at surplus stores, or ask a computer nerd friend if they have any extras. I had three that provided the voltage and current required by the ELK-120.

Project Update: Pneumatic Toe Pincher Coffin, Part 4

Christmas gifts for nerdlings

When I was around 11 years old, a friend of the family gave me a Radio Shack 150-in-one electronics kit. I thought it was absolutely amazing and made many of the projects in the big instruction book. A friend of mine got Capsela which I had never seen before. Similar idea, but more for the mechanically inclined. I had the Erector Set.

Elenco 130-in-1 Electronic Playground and Learning Center

Meccano Super Construction Set

Capsela

If you know a child with an interest in electronics (I demonstrated an interest by taking apart the toaster, plugging all the extra extension cords together and dragging them around the house) or mechanics, pick up one or more of these kits this holiday season.

In addition, electronics and mechanical engineering skills equal a head start on robotic science.

Parallel Resistor table

Here's a handy table to find three resistors you can put in parallel to achieve a more precise target resistance. Great for LED voltage drops.



View on Google Docs (click the down arrow in the upper right corner to download)
or Download .zip

UV LED miniature spotlights with snoot

I hate when people can see the light bulbs! What's nice about ultraviolet lighting is the amount of visible light is much less. An object painted with fluorescent paint shifts the UV light into the visible spectrum.