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Rob's Prop-1 Breakbeam Trigger using a Solar Patio Light

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This how-to project comes from GoE member Rob "High Tech" Horton. This is an awesome example of a haunter creating a really cool hack out of an everyday item.

The spark for this idea came from Rob's need to create a Prop1 controlled break beam. For the Prop2 this is a no-brainer, you buy about 2 bucks worth of parts and use a laser pointer and you're done. On the Prop1 however the lack of RCTIME function and much slower speed make it klugey at best and most all folks that I know just spend the money on (usually expensive) surplus break beams.

Well Rob to the rescue! Break beams are 1000% x200 + America, F YEAH!! better than PIR sensors. To be diplomatic, PIR sensors SUCK BIG SWEATY DONKEY BALLS with Halloween prop applications. This is mainly because they take way to long to re-learn their environment, and are very prone to false positives.

A break beam is the hotness, and all of us Prop1 guys have Rob to thank for making it dirt cheap affordable!

Without further rambling, Rob's totally sweet solar yard light based Prop1 break beam hack:

A break-beam trigger for the Prop-1
By Rob "High Tech" Horton

As we've learned the hard way at the Garage of Evil, the Prop-1 does not support the RCTime command that makes building a break-beam for the Prop-2 so simple. So here's another way to go about it. All you need is a solar patio light, a few tools and some time.

The beauty of this is that there's no special code needed to make this work. As far as the Prop-1 is concerned, this is just another simple On/Off trigger. J

Here's what you'll need:

• 1 solar patio light (battery powered LED)
• screwdriver
• wire cutters
• soldering iron
• 1 AA x2 battery holder
• a frosty beverage or 3
• and some time

OK, here's our intended victim, your standard battery-powered, solar LED patio light. How innocent and unassuming it looks. But we're haunters! Let's see what we can do to fix that!

And here's a look at the top. Notice the white dot on the top. This is where the CDS cell (photoresistor) lives that tells the light if it's dark enough to turn on.

I know what you're thinking, "That's kinda bulky for a break-beam, isn't it?" Don't worry, we're working on that. Let begin by opening this thing up and getting at the guts of it, the part we really want.

First open up the light, then remove the reflector/diffuser exposing the batteries. I'd recommend removing the batteries before we start chopping wires and whatnot.

Note: A frosty beverage is always near at hand. I recommend at least a sip or 2 between steps.

Now, undo any screws around the batteries to gain access to the internals (circuit board, LED, etc. The blue wires in this photo are the leads to the CDS cell. Leave those intact, but go ahead and cut the solar cell leads. Mine were yellow and black. You'll notice I've already cut them below. I always like to leave a workable amount of wire behind in case things get repurposed for a later project. No sense making your future self angry for you being shortsighted, right?

For my version of this, I decided not to make use of the solar cells. But like any good haunter, I set them aside for some other use later. You could use them though if you plan to use this for several nights. Longer leads to a hidden location outdoors, the solar cells will recharge your batteries. In which case I recommend keeping the Ni-Cd batteries the light came with. Otherwise, any set of AAs will get the job done.

OK, now let's get the circuit board out of there, shall we? You'll notice here I've cut the red and black battery leads in preparation for removal of the board.

With the wires all cut, only 2 screws hold the board in place. Let's undo those and free the board from the light entirely.

I know, I know. Now we've got an LED sitting here with no power, no connector, and well… looking kinda lost at the moment. Don't worry, I AM going somewhere with this. This is what you pay for not having to write all that pesky code. :p

So, let's work on making this Prop-1 friendly. First, get your soldering iron (hopefully you've already let it warm up. If not, crack open another beverage and enjoy for a few minutes) and remove the LED. We're going to be replacing it with 2 wires that will connect to the Prop-1 as you see below.

Here you'll see the "stock" version (left) and our newly modified break-beam trigger (right).

For the connector, I made use of one of the many "Try Me" buttons you'll get on most any electronic prop you buy. You've seen them I'm sure. That little button on the package that let's you try it briefly while you're in the store to see what it does. SAVE THOSE!! They come in damn handy as test triggers, switches for things in general, or in this case to be hacked for the connector ends which sit nicely on the pins of the Prop-1 once you remove them from the plastic plug.

BTW, I saved the microswitch that was inside the white button for future use. Again, very handy to have around. ;)

It's not as pretty as those nice 3-pin extension wires you can buy, but I had them and they were "free". So why not use them, right?

Now, hook up your AA battery holder I mentioned way back in the beginning and you're ready to connect this to your Prop-1.

Now, a few useful pieces of info from the good people at EFX-TEK.

• The Prop-1 can handle up to 5V input on the white pin
  
• Anything above 1.5V IN on the White pin will be seen as "1" or HIGH
  
• You will not use the Red pin on the Prop-1 for this.
  

Go ahead and hook this up to your Prop-1 as you would any other trigger. Positive lead to the White pin, Negative lead to the Black pin. While light is on the CDS cell, the power remains off. In my case I'll use a laser pointer for a nice tight beam. The Prop-1 will see this as the trigger being LOW or "0". When the beam is broken, even momentarily, the power comes on at ~3V and the Prop-1 reads this as HIGH or "1" and will then execute the code you've programmed.

Response time seems to be the same as any other trigger. Any delay you want or need will need to be done with code. A simple PAUSE command will take care of that with ease.

So, to review in a nutshell:

1. Remove the electronic guts from the solar light
2. Replace the LED with 2 wire leads
3. Attach 2 AA batteries to power the unit
4. Attach the leads to the Prop-1 (+ to white, - to black)
5. Program your triggered Prop-1 code as usual

It really is that simple! Good luck! :)

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