# Need a Door Knocker/Shaker



## heresjohnny (Feb 15, 2006)

I need a way to drive something that will either rattle the knob of, or bang on a door. The idea is to wait a few seconds, then knock or rattle 2 or 3 times, then repeat. I would like to do this without a prop-1 or equivalent, I was thinking more a simple circuit maybe based around a 555 and a counter. Anybody know about something like this, or have any ideas? Thanks!


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## airscapes (Oct 3, 2006)

You can use a wiper motor with 2 rubber caster type wheels mounted on the ends of a shaft as the motor turns the wheels hit the door and push it open or just knock depending on how far back the motor assmble is from the door. I don't have a picture but I use it to open and close my thumping coffin and a motion sensor to turn on the 12v battery chargher. Lots of example circuits on the web for the 555 here is a good site.
http://home.cogeco.ca/~rpaisley4/LM555.html
Do a google for 555 timer you will find others.. Good luck!


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## heresjohnny (Feb 15, 2006)

airscapes said:


> You can use a wiper motor with 2 rubber caster type wheels mounted on the ends of a shaft as the motor turns the wheels hit the door and push it open or just knock depending on how far back the motor assmble is from the door. I don't have a picture but I use it to open and close my thumping coffin and a motion sensor to turn on the 12v battery chargher. Lots of example circuits on the web for the 555 here is a good site.
> http://home.cogeco.ca/~rpaisley4/LM555.html
> Do a google for 555 timer you will find others.. Good luck!


Thanks airscapes, I will check out the circuits, been looking on line but best thing I found so far is set up a big counter, latch a flip flop to one of the outputs with the clock from the 555, and trigger when ever that particular output is high.

What I need to find is how to hook up the 555 to some counters so I can have some control over how many tics to wait between triggers, and once I trigger how many pulses to count (and 'knock' on for example) before resetting everything for the next go around. If I could somehow sample the counter and use that set how high to count before the next triggering sequence, that may give me a psuedo random action.


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## Otaku (Dec 3, 2004)

HJ - I answered your query over on Halloween Forum.


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