Sometimes You Don’t Plan on the Hardest Thing—Building IT Part VI

Greetings Halloween Geeks and Geeks adjacent! Here is a picture of the IT prop “in-the-bones.” In other words, there is no skin. When I last reported I had everything working on the bench—separately. Turns out that is an important distinction. Everything worked and when assembled, it didn’t. It’s like reverse synergism. I anticipated a problem with mating the store bought jumping spider with the homemade portion. I did encounter that problem and found a solution quickly (and elegantly). Elegantly in that the finished prop will no longer require a set of AA batteries be installed in the spider. The solution was to split power from the main supply, regulate it, and provide it to the spider only when required. It took a bit of fiddling but now works fine. However, I didn’t anticipate that the noisy auto antenna motor would interfere with the audio amplifier.

As I said, each element worked independently. The voice sounded great from the reclaimed PA speaker horn when it said “Beep beep Kiddie. They ALL float down here. When you’re down here with us, you’ll float too! They all float down here.” The clown descended creepily down into the toilet. The spider looked scary as it slid forward. After a very slight slide backwards, the spider jumps and makes noise that seems to fit the situation. Once the spider backs down, the tray moves the spider back and the clown rises once again from the toilet. Beautiful! Except, the voice only worked once and was silent in subsequent cycles. WTF?

What follows is some “deep geek” discussion.

I tried everything to isolate the problem. Remember that the only time there was a problem is when everything was connected together. I didn’t have a clue about how to fix the problem.

I replaced the 12V power supply with a deep cycle 12V marine battery—no improvement. I powered the FX and sound board with a separate power supply and that didn’t fix the problem. Frustration started to be the order of the day. Nothing I tried made any difference. The problem got worse with each cycle and that made the problem harder to troubleshoot.

Before I became an electrical engineer, I was an experienced technician. It knew it would take every skill I had to find what was causing this situation. Isolating the audio board power supply didn’t work. Isolating the triggering connection to the audio board also didn’t work. I reasoned that there must be radio frequency interference from the auto antenna actuators.

A quick Google query gave me website on “Dealing with Motor Noise.” I followed the instructions half believing that I was wasting my time. Fortunately, the problem went away—completely!

The next installment will include a video of the completed IT prop in action. Today is the 1st of October and I feel great that my 2017 new prop is nearing completion. There are dozens of small projects that must be completed before the end of the month and I may not get to everyone but at least the IT prop will be there for the kids on Halloween.

About AZAtheist

Retired--Researcher, Developer, Program Manager, Arizona Regional Director--American Atheists, Organizer--Tucson Atheists, Organizer--Skeptics of Tucson
This entry was posted in Halloween, Repurposing Material, Retired--A Day in the Life, Science and Technology and tagged , , , , , , , , , , . Bookmark the permalink.

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