# How to build a simple John Doe prop?



## roadkill_be (Jun 14, 2012)

I would like to have this prop for my asylum scene

johndoe_zpss6dhlvzn.jpeg Photo by Noben | Photobucket

But I can't buy it here and online is also no option because the shipping is more then the costs of the prop, so the only option is making it myself.

Does anyone build something like this? And how? I can't use pneumatics but have a wiper motor

Any tips, schematics etc are welcome


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## RoxyBlue (Oct 6, 2008)

I've moved you to Tech Terror where the folks who know motors hang out


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## roadkill_be (Jun 14, 2012)

tnx


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## JeffHaas (Sep 7, 2010)

There's a few parts of making this prop:
- Running the motor forwards and backwards (making the body sit up and lie down)
- Creating a frame for the prop, probably out of PVC pipe, and then putting hinges on it so part of it can sit up. Then the frame can be filled out with bubble wrap to suggest a body and you can cover it with a sheet.
- Control of the prop. Simple timer, or a microcontroller with a motion sensor, or a couple of buttons that someone hidden can press at the right time?

Search for info on all these topics, there are a ton of them on using wiper motors, and lots on making the "skeleton" of a body out of PVC. You'll have to do some tinkering to figure out where to put the wiper motor and how to attach it so it moves the upper half of the frame correctly.

That should get you started! There is lots out there, don't forget the Instructables website as well.


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## DarkOne (Oct 16, 2012)

Look at Scary Terry's kicking legs here.

http://www.scary-terry.com/kicklegs/kicklegs.htm

With a simple arm controlling the motion you won't need to use and H-bridge to reverse the motor.

To control it, I would use a microcontroller like an Arduino nano clone from ebay with two leaf switches to act as limit switches. as the body comes up, it hits one switch placed where you want it to stop. ( probably somewhere where the prop can continue to move as it hits it in case the motor doesn't immediately stop and also at the top of the arc of the motor movement before the arm pulls the body back down) This switch will tell the microcontroller to stop the motor. After a delay, the controller restarts the motor, it moves the body down until it hits the second switch at the other end of the arc.

A relay can be used to control voltage to the motor instead of a motor controller if you don't mind a clicking noise when it starts and stops or software controlled speed adjustments. If your Asylum has loud music or sound effects, the clicking shouldn't be a problem. Or something like a TIP142 10amp transistor should work as well, no clicking. I've made an H-bridge with these and TIP147s but never used one just to turn on a motor, but I don't see why it wouldn't work, I'd probably use a heatsink.

Looks like a cool prop. Good luck!

Psuedo code for microcontroller

read sensor
if spectator present
turn on relay/transistor
wait for switch one to be pressed
turn off relay/transistor
delay 
Turn on relay/transistor
wait for switch two to be pressed
turn off relay/transistor
delay( use this so it doesn't repeat immediately if spectator is there when it goes down)

code will repeat from the top


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