Halloween Prop – With strobe, MP3 playback and Air Cannon

[guitartoys]

Hi,

Love the defusable clock, and want to make a pretty neat Halloween prop for next year. I already have all of the other parts, just in the process of making the box.

My intentions are thus:

Have a box, when opened performs the button push for the countdown. (Lid will lock open, so the person can’t just close the lid and walk away.)

I can rig another button with the lid opening, so at the same time trip a MP3 player yelling at the person for opening the box. The audio playback will also be timed with the explosion event, or potentially have the clock trigger a second track. So I’ll have a good explosion sound (already layered one for my son for another project)

Might rig a rotating police type light to be also tripped when the lid is opened.

Can I program a pin someplace on the device to trigger the playback? So if I want to delay the playback for a second or so I can?

When the clock blows up, I’d like to have two things occur.

First I need to trigger an LED strobe for a few seconds (I’d like to be able to program how long this ultimately is a couple of seconds should do. Just a high signal held would be fine. (I bought some Ramsey LED strobe kits)

In addition, I have a 12V air compressor valve, and want to trip that at the same time as the LEDs, obviously, can use the the same trigger pin as the LED, will just need to put a transistor in for voltage and current of the valve. I plan to tuck streamers into the box, so when the valve trips, the person not only gets a blast of air in the face, but the streamers too.

So basically all I need are 2 programmable pins one delayed slightly for the MP3 playback, and the other to coincide with the explosion, that I can program the length.

I’d like to keep the existing led flashing sequence on the unit if possible.

And lastly, do you offer the code to allow me to just edit what you have, rather than reinventing the wheel.

Thanks.

Michael

[Michael]

That sounds like a pretty cool (and ambitious) project. The Defusable Clock uses all the pins of the ATmega328, so the best way to get the 2 control pins is to repurpose two of the LEDs. If you can desolder them (or tap into the signal at the accompanying resistor), then you could use these to control your peripheral devices.

The code for the clock is downloadable from this page, and easily compiled in the Arduino IDE:
http://nootropicdesign.com/defusableclock/hack.html

I think you’ll find it easy to modify if you are an experienced programmer.

[guitartoys]

As I won’t be using the 4 disarm wires, I trust I can just re-purpose them? Yes? Oh, maybe not, as they may be input channels? It looks like one end is just a ground (or +) block and then other end are the signal wires going to the controller?

Or would just grabbing 2 of the LED lines be better?

I probably won’t get the box built until the Christmas break, but will take photos along the way to show progress.

This will be fun.

Thanks.

Michael

[Michael]

You are correct. You can use these 4 lines from the microcontroller to control your devices. They can be configured as input or output pins in software. This would be a much easier way to connect everything — you even have handy terminal blocks and 4 ground connections on the left set of blocks.

[Author]

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