Thread: Varying wiper motor speed in MIB prop

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Okay... i just finished converting a homemade toe-pincher coffin into a Monster in the Box prop using a wiper motor / cam shaft set up. My initial plan was to run in off a PIR set in test mode so that it would only run for a few seconds. However, even at that rate, the banging still sounds mechanical. Does anyone have any simple solutions to randomly change the voltage to the motor to change the speed and make it sound less rhythmic and mechanical?

Any help would be greatly appreciated...

John

Hmmm, the key word here is "simple." You could program a series of commands to make the routine look 'random' on a prop controller board like a prop-1. The prop-1 then would drive a Parallax HB-25 DC motor controller which would vary the speed of the motor according to the program you wrote.

Could you instead create a bigger cam (to give you a longer routine) and then slow the motor down using a simple speed controller?

I'm planning on using a Prop1 controller with 2 SPDT and 1 DPDT relays. I created a program for it to randomly change the wiper speed (Hi/Lo), direction (forward/reverse) and power input from a pc power supply (+12 volts/+5 volts) at random time intervals. This should give me a really random type of movement. Just have to finish wiring it up and test it out on my ground breaker.

Yeah... that's what I was afraid of... Thanks guys!

What does your cam look like? Something like this setup works well for adding some randomness to the banging lid. http://cindybob.com/halloween/mib/

Also, you can put a turn signal flasher in the motor's circuit for a little additional randomness.

You can get by without a expensive prop controller by using a blinker fuse or two in the line and leave a loose connection on bolt (what ever you use to connect it to the top). This will give you a some what random movement. A lot better than the back and forth, back and forth.

You could put a flourescent bulb starter inline and that would probably also add some randomness to it. Thead on how to do it here:

http://halloweenpropmaster.com/u-build-it3.htm

Here is an electric chair I built using one so you can see how it works.

Another Electric Chair

Here's a few props that I used the blinker fuse or a loose connection on

In this one watch the rock and how it moves and you will see sometimes it will move a little and others a lot. I have other pictures of this one here http://s985.photobucket.com/albums/a...0motor%20prop/





Used nothing on this picture but the wiper motor


Used a blinker fuse on this one



Used nothing on this one



I used a loose connection on this one watch closely and you will see long and short movements on the door



This is a loose connection... the piston slides on the bolt if you look closely you will see a gap of about 1 inch on the bolt



It's hard to see in this picture but the arm/piston isn't connected tightly to the pvc on my electric chair prop. This lets the piston slide up or down the pvc to get a jerky movement.



This is bad picture and you can't tell much from it but I'm using a loose connection on it also.



See the bolt in the bottom left corner, the piston/arm fits over it and that allows it to slide on the bolt to get a jerky movement.

Thanks a lot guys. This gives me some hope of making a less mechanical looking MIB. I might try an amalgamation of the three variations here to see how it looks - blinker fuse, fluorescent starter and loose connections... Will post video when finished.