bit of testing when disaster struck. We triggered
the prop and it proceeded to lunge forward, but it
didn’t stop! Imagine the horror on our faces as we
watched the prop try to pull itself apart. We heard
the sound of springs stretching and parts breaking
as the side walls were being pulled together. I ran
to the back of the crypt, frantically yanking the
power to the controller. Shaking our heads, we
looked at each other in disbelief. Turns out the
sensor that told the motor to stop had failed. The
foam walls and PVC pipe frame were no match for
the power of the drill.
We took the sides off the crypt and assessed
the damage. Lucky for us, the flexible nature of our
building materials saved the prop from serious
issues. One cable had broken, there were a few cracks in
the foam walls, and the frame had come a bit loose in
places. Other than that, the prop was surprisingly intact.
We were able to patch the few cracks and reattach the
cables, then double-check the sensors. In short order, we
had the creature back in business! I have to hand it to my
brother. If it wasn’t for all his donations to the project and
staying up until the wee hours in the morning after this
failure, the prop would never have been finished for
Halloween 2010. The prop did debut the next day to scare
quite a few people (Figure 17) but with one little change: a
kill switch in the front! NV
September 2014 93
FIGURE 16. The wooden frame
for the crypt taking shape.
FIGURE 17. The crypt in
place and ready to scare for
the Halloween season!
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Simple, Reliable, Affordable
I used Altronix Corp 6062s as I had a few of them in my junk box:
These are industrial strength timers typically used for alarm systems and
industrial automation. For this application, they're definitely overkill.
A cheaper alternative would be the 555 timer kit from Velleman available
timer-kit--320-184. This Velleman part can be used to replace the 6062s
and the custom 555 timer I built from scratch.
I used a garage door opener remote from my junkbox, but if you don't
happen to have one laying around, All Electronnics has a workable remote:
You can pick up relays on many surplus sites. Some suitable candidates for
this project include:
For portability and simplicity, I ran this prop on a 12V battery. If you prefer
to run on 110 VAC, some suitable candidates for power are:
Once again, I hit my junkbox for the audio, but if you don't have an extra
power amp laying around, check these out: