Oh what a night!

To say thank you, seems such an underpowered statement, but Thank You!!!  Christopher, Zack, Laura, Jeremy, Emily, Luke, Steve, Scott, and of course my mother.


I could not have pulled off such a wonderful night without you all!  I am eternally grateful for all of your help, professional behavior, and your willingness to put up with some of my more eccentric behaviors and requests.

We had 339 kids, and 5 dogs that made it to the porch this year, shy of last years total by 9 kids.  Never the less we put on one incredible show and I could not have done it without all of your help.

What are you all doing next Halloween? 🙂

Laura and her camera were everywhere taking WONDERFUL shots of the action, which I will post soon, Jeremy took video for me which I will look over and post some of that when I get the chance, and Scott also took a bunch of pictures and once I get them I will post them as well.


So, what’s that wierd box for John?

A few months back I posted a picture of a strange looking box. I also asked people to guess what the box did. There were some good guess, but none that hit it 100%.

The box, contained a programmable micro controller board. It also contained a small circuit to interface with the “Try Me” button for an off the shelf Gargoyle I bought at Walgreens.

The box, combined with the gargoyle, some home brew LED spotlights, a hacked Dance Dance Revolution Mat, a plaster pedestal I painted to look like marble, and a nice alcove in a set of our bushes, creates my latest scene for Halloween.

The visitor walks past a set of bushes, when suddenly the alcove lights up, showing a gargoyle, the gargoyle opens his eyes, and begins to speak. When he is finished, he closes his eyes again, and the lights dim.

Just imagine the fun this will cause.

RF Remote Prop-1 interface

Today, I finished creating the Prop-1 to RC controller interface circuit. The schematic, for ExpressSCH is available here.

Interface Schematic
Interface Schematic

It works like a charm, all simple transistor logic, no relays, no nothing. Now, with a simple 3 lines of code in the Prop-1 program I can remotely trigger a prop ~30 feet away.

LOW Bkwd

Completed circuit
Completed circuit

One cool thing of note, I submitted the schematic to the support forum for the Prop-1. The head programmer / developer gave it his ok, and complimented me on part of the design.

More on the remote front

Well, I couldn’t stop at just the crow, and the flying ghoul. I found in my bins of stuff a screaming head I got from Target a few years ago. I never did set it out anywhere, but I took a look at it, and found it was indeed quite hackable. I dropped in the receiver board from another of the remote control cars. This time though, I had already used the Forward,and Reverse signals for other props, so had to do a little hacking to the receiver. Fortunately the chip in the car is capable of five separate actions, and the chipset is documented on the net, so I used one of the unused channels and linked it into the head. I then had to build a remote that had buttons for all five signals. I built that, finished the interfacing of the receiver and now have the ability to trigger the head from a remote. Tomorrow morning I’ll build a second transmitter for the Prop-1 to use to transmit.

Quote the raven… “Wireless”

Ok, so really it’s not a raven, it’s a crow…

A few years ago, when I got my first Prop-1 controller form EFX-TEK I set it up to control my popup jumper, and my squawking crow. Initially, the only way I could come up with a way to set off the crow was to insert a relay inline with the “try me” button on its bottom. This worked fine, except that it had the distinct disadvantage of requiring a cable leading from the crow to the controller. Later After I had that all working, I purchased a ghoul that “flew” down a rope and back. It too had a poor activation method, that I wanted to bypass. This time, due to the nature of the prop, I could NOT use any wired connection. This meant wireless. I looked online for some wireless transmitters and receivers, and found them to be cost prohibitive. This annoyed me greatly, until I was browsing the clearance isle at Wal-Mart and found a radio controlled car for $1. At that, an idea was born. I quickly snatched up the car, and dismantled it in the parking lot. I looked over the circuits to find they looked very simple, and easily modifiable. So I drove to radio shack, picked up a few parts and when I got home wired a buzzer up in place of one of the motors, and glued the receiver, and a separate power pack under the gouls cloak, and sure enough, when i pressed a button on the remote, the ghoul would hear the buzzer and start moving. I wasn’t thinking then, as I shoudl have went back and picked up 4 more of the RC cars to allow me to control up to 5 items (forward, reverse, left, right, turbo) from the one controller.
Flash forward to today, I recently went to the dollar store and picked up 5 cheap RC cars, all to my luck, having very tiny receiver boards. This morning, I sat down with the receiver board, and using my limited knowledge of electronics, wired it directly into my crows control circuitry. Now, the crow still functions as it did out of the box, but also sports a fully internal radio receiver. With the press of a button on the remote, or once I’m done, a signal from the micro-controller running the show, the crow will activate. Best part, there are NO wires, I can put the crow anywhere within a 15 ft radius of the transmitter and still have him work just fine. This should, in theory, also allow me to carry a controller with me where I can trigger him, and other props at will. MUAHAHAHAHAHAAHAHAHAHAH

Down in a hole…

It is said, a friend will help you kill someone, but a real friend will help you bury the body.

Karl entrenched
Karl entrenched

Well, qualifies as a real friend. (Not that that was ever in doubt) Ok so there wasn’t actually a body, but I know very few people that would drive out here to help me dig a two foot deep trench, (26 to 28 inches in some places) to help me bury conduit to repair my yard light.

Eighteen years ago while planting a rose bush for my mother, I accidentally cut through the direct burial cable that ran to our yard light. This of course sucked badly, fortunately I was extremely lucky and was not harmed. So, with nothing more than a shoestring budget, I set out to repair the light. I made quite a few mistakes, but the end result had the wiring in conduit, and a little safer. It lasted for quite a few years. The past two years I started having trouble with it tripping the ground fault interrupter a lot, and I decided that I would need to replace it all again. Now that I have a full time job, and have paid off all my credit card debt, I could afford to do it right.

Burying Karl
Burying Karl

Today, at around 11:00, Karl arrived to find me digging the beginnings of the new trench for the conduit. After a few shovel fulls of dirt the larger shovel split its handle out, so we ran to go buy some better shovels for the job. After returning we trenched, by hand, a 30 foot long trench that ranged from 26″ to 28″ inches deep and ran from my house to the yard light. It took us a while, but we did it, and I am glad that the conduit is now the recommended dept. Previously when I did it myself at age 14, I was a lazy bum and the “trench” was no more than 6 inches below ground… I knew that was too shallow, but at 14, I didn’t care. Once the trench was dug, we set about laying the conduit. As we did I discovered, the outdoor outlet post I had purchased had an added surprise. It could be configured, through the use of an insert into a dual purpose, high and low voltage post. I couldn’t resist this opportunity so while I set about cleaning up the underground knock out hole in the lamp post Karl headed off to get more conduit so I could have a separate run of conduit for low voltage items, such as speaker wire, video, or data. Just imagine the possibilities if what I could do if my yard is wired for sound… MUAHAHAHAHAHAHAHAHA be afraid, be very afraid…

By the time Karl returned, I had ran the wire for the lamp post to the outlet post, and while he assembled the low voltage conduit run, I ran the wire from the outlet post back to the house. Once that was done, and all of the connections were made, we tested the circuit, and everything checked out. It’s important to note, that Karl changed the blown light bulb for me, the real reason the light was not working the past month… (Ok, simplest solution, I know….)

Now though, I feel 100% safe in the knowledge that the wiring to the yard, that I rely on heavily for Halloween, and Christmas displays is now safe, and water tight. Thank you Karl, Thank you Ladies at Ace Hardware who must have thought we were nuts… Oh, and thank you neighbors, who stopped to ask if I was working on my Halloween display… MUAHAHAHAH… Ya know… I should have ran a 3rd conduit while we were at it… one for Pneumatics… 🙂 Oh well, next time… 🙂 Hey Karl, what are you doing tomorrow? 😉

Low Cost Foor Mat Switch

One of the biggest problems with having a lot of props, is the need to trigger them. Store bought props usually come with cheap photo sensors that never really work well. PIR sensors work pretty well if you can shield them from excess sources of IR, like direct sunlight. A third option, one that tends to be quite expensive, is the use of a floor mat switch.

Floor mat switches are at their simplest form to conductive materials arranged in some manner to allow the conductive components to remain separated until weight is applied. (Someone steps on them) While the weight is applied, the conductive components make contact and complete the circuit. After the weight is removed, the contacts again separate and break the circuit. This makes for a pretty reliable guest sensor, as the mat is not affected by sources IR and false triggering is pretty unlikely.

As I mentioned before, the biggest drawback to the mat switch, is the cost. Most mat switches are designed for use in industrial equipment for safety purposes, and are therefore rated for heavy usage. One night a year doesn’t seem to justify the ~$200 expense. One day as I was leaving the movies I saw a group of kids playing Dance Dance Revolution (DDR), and it hit me. There are tons of copies of DDR out there, and there are millions of cheep imported mats to work with your home entertainment system. A quick search of ebay found 2 Chinese import lower quality mats for $20. At $10 a piece, thats MUCH MORE suitable for a one day a year use.

Controller guts
Controller guts

Hacking the mat turned out to be a pretty simple task, as I had expected. The controller electronics are located in a black box at the top of the mat. Opening the box, on the model of mat I purchased was as simple as unscrewing 6 screws on the back side. From there I was able to get a good look inside the mat. The low cost DDR mat, is at its heart two sheets of thin plastic, with carbon traces printed on them, separated by a thin sheet of foam similar to that used in packing fragile materials. The foam layer is punched with numerous holes under each “button”. The bottom layer acts as a ground plane and when pressure is applied the foam compresses allowing the top and bottom layers to meet, making contact. This change in resistance is then fed to a specialty chip located on the PCB that converts the contact to a signal usable by the video game system. While it is certainly possible to decode that signal and use it without altering the mat it would add more expense and therefore not acceptable for this application.

For my needs I didn’t really need separate signals from the individual buttons. I just wanted the whole mat to act as a giant switch.

Bridging the Switches
Bridging the Switches

For a while I toyed with the idea of taking the columns of the mat individual switches giving me a way to detect direction but the mat is actually small enough that i decided that wouldn’t be to useful. I broke out the Multimeter and started mapping out the lines from the various switches on the mat. The board contained a row of 0.1uF disc capacitors likely used for denouncing the controller circuit. I was planning on doing debouncing in software so I removed the capacitors and used their solder pads to tie all of the switches together, this was accomplished by taking a small piece of bare copper wire and soldering it across all of the connections. The mats connections were split to two sides of the board so this actually required two pieces of bare wire, and a small jumper to connect them.

Once the individual switches on the mat were bridged I attached two of the original wires from the mat cable to the pads for the contact, one to the ground plane, and one to a trace leading to the now bridged contacts. I then took my multimeter and set it for continuity testing, and attached it to the other end of the cable. It immediately started behaving oddly. I decided this strange behavior has something to do with the controller chip still being in circuit. so, I took my razor knife and carefully cut all of the traces leading to the chip, without damaging the traces needed for and of the switches. ( Ok really, technically i accidentally nicked the ground lead and had to move my ground wire form its original location to another location, but as long as you are careful you wont run into that problem. 🙂 ) After disconnecting the chip, the multimeter returned to its expected behavior. With no pressure on the mat the mat read an open connection. Once I pt pressure on one of the pads, the continuity tester beeped, and resistance dropped to around 1500 – 600 ohms depending on the amount of pressure applied.

I then decided, while I had the mat open, and i had extra wires in the cable, I would add in an LED for future use. This was simple enough, I drilled a 5mm hole, pushed in the LED, and soldered two of the cable wires to the LED. I then closed up the box, and now have a low cost mat switch that can be attached to anything.


Use ideas:

  • Solder it in place of the Try Me button on a prop from a big box store. (Note: Some try me buttons also turn off the prop if they are pressed a second time, so a simple event timer circuit may be needed. Theres plenty of room in the mat switch control box to house this, by the way)
  • Input to a PROP-1 controller. (Sky’s the limit here folks. Remember, the resistance varies with the amount of pressure applied… so you might be able to use the POT command for some rally cool efects)
  • Use it to directly switch LED’s to light some gruesome scene. AGAIN NO DIRECT HIGH VOLTAGE / CURRENT APPLICATIONS
  • Hook it to a low voltage relay to power more power hungry applications.

Your mileage may vary, the author of this article is NOT responsible or any damage to property, personal injury, or any other problems that arise from using this hack.

If you like it, and it works for you, I’d love to know about it, send me an e-mail to john@wohlershome.net

L.E.D. Fun

What do you get when you combine 24 awg stranded 2 conductor wire with a resistor, and a high intensity L.E.D.?

You get a really awesome spotlight so small that it can be easily hidden in even the smallest tree beach and yet illuminate a scene plenty bright enought.

Tonight, I wired 5 of these. 2 blue, 2green, and 1 red. Tomorrow I hope to make the housing for them.

Nightmare? Premonition?

I had a very strange experience this morning. At 4:27 a.m. I awoke from what was an incredibly vivid dream. When I awoke I was still choking on smoke and could even taste it… The dream was so vivid… This is what I saw.

I found myself standing along side of my car at an airport I didn’t recognize. Strangly I was near the runway and the terminal or some hangar building, I didn’t get a good look. As I was standing there I became aware of a large jet prepairing to take off. At that my point of view shifted to a point in the air above the runway. I was then able to see another jet in parallel to the 1st jet, this jet was sitting as if waiting for clearance to take off. As the 1st jet taxied past this 2nd jet the 2nd jet exploded with a force so large that the explosion tore the 1st jet apart. Then the perception changed again and I was back on the ground, running from the debris. The tail section of one of the planes came tumbling towards me riding the front of the blast. It looked almost as if it were a pin wheel. The black cloud of smoke engulfed everything as the tail section crashed into the building behind me. As the collision occurred I could hear the screams and wailing of countless people. As the smoke engulfed me and I began choaking awake, I heard the disembodied voice of a television announcer discussing the horrific tragedy involving an Air France flight and… Then I was fully awake still choaking, still tasting the horrible fumesl. I turned on the lights and half expected the room to be full of smoke, but it wasn’t… Within seconds my sence of smell returned to normal and all was well. I laid there staring at the fan trying to make sence of what just happened.