Piecax the Poltergeist. a Troublesome Spirit in a Box.




Introduction: Piecax the Poltergeist. a Troublesome Spirit in a Box.

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Poltergeist : From the German for “noisy ghost”.
A metaphysical entity which announces its presence with rapping, banging and general mischief making.

It wasn’t easy, but I’ve got one shut up in this box. I call him Piecax. Sometimes he will lie quietly and make you think he’s gone, then startle you with frenzied knocking. Other times Piecax will have fun by echoing you. Find his favourite number and he might play you a spooky tune. Watch the video to see Piecax in action.

Thanks and credit go to JKestner whose Knock Block gave me the inspiration for this project.

Step 1: The Box

I did this first so I wouldn’t be waiting for varnish to dry once I’d built the circuitry.

I started with a cheap softwood box from a craft shop.  I clamped a rotary sander upside-down in a vice and rounded the corners and smoothed the sides, starting with a coarse sanding sheet and finishing off with fine.  A final rub over with very fine paper and I had a smooth rounded box but a bit of a boring colour.

To bring out the grain I gave it two coats of walnut woodstain  and then for the gloss, three coats of yacht varnish.  The first coat was diluted with thinners to make it soak into the wood and give it more hardness and a good base for the other coats.

A quick raid on my sons' lego sets and I had a casket fit for a ghost.

Step 2: The Electronics

*  This section has gone missing.   *
*  I'll re-write when I get a chance.  *

Step 3: The Mechanics

The various parts are stuck on with contact adhesive (that’s the type where you apply a thin coat to both surfaces, wait a few minutes, then it sticks hard immediately you put the parts together.)  The sounder is glued to the lid so it picks up the vibrations directly as the top is tapped.

For the ‘knocker’ I used a small 3V DC motor with a piece of brass strip bent fixed to the shaft.  I bent this to shape with a pair of pliers so it was a push-fit onto the shaft.   Be careful as you push it on as the plastic back of the motor is likely to push out, so put a hard object on the end and push against that.

The motor came with a solar cell kit and had the plastic clip with it.  Alternatively you could use a piece of split overflow pipe with one side sanded down, or use double-sided sticky foam to attach the motor to the box.  Later on, I added solder to the end to give a good solid knock.  A bit of trial and error is required to give the best weight.

Step 4: Putting the Ghost in the Box.

With the box size I used, everything goes in pretty easily and neatly. You will need to adapt the layout if you use a different size or shape of box.

The battery is held in with double-sided sticky foam so it can be replaced.  The circuit board in held in the same way, and has to go in before the motor if you're using a small box.

Gluing a small piece of brass strip to the lid where the knocker hits gives a sharper knock and helps the knocker to return quickly.  The final picture shows a piece of foam glued in to dampen the 'clunk' when the arm returns.

Click HERE for information about the standard training video for containment of supernatural beings.

Step 5: The PicAxe and Code

The code is here as a PicAxe .BAS file and as a Word document.  There are loads of comments throughout to explain what's going on in the program.  It uses 252 memory bytes of the 256 available.

20 knocks will give a 30 second sleep and then a series of 50 rapid random knocks; Long enough to put the box down in front of someone and tell them the spooky story of what it contains before it bursts into life.
13 knocks will play a tune which strikes fear and horror into the hearts of many - the 'Adams Family' theme tune.

I've used a PicAxe 08M microcontroller which comes as a blank chip and needs to be programmed. To do this, you will need a programming lead and the free programming editor software. Both the PicAxe chip and the lead are available from Tech Supplies in the UK or see HERE for other countries.
Once you have the lead, you only need a PicAxe, two resistors and whatever sensors and output devices you choose to have a full PicAxe development kit which can program any of the PicAxe range, so you can design your own projects.

The PicAxe was initially developed for the educational market in UK schools but is being widely used by hobbyists. The PicAxe is based on various PICs but with bootstrap code to interpret the downloaded programs and handle the programming side. They come in all flavours from this suprisingly powerful 8 pin package up to full blown 40 pin.
Look at the manuals and datasheets on the PicAxe site to see the full capabilities. Programming of the chip is via a serial link and done in-circuit. It takes about 20 seconds and you don't even have to unplug the lead to run the program.
I've been in electronics since the early eighties and I've never found a programming environment where the coding / simulation / proving cycle is so simple. Documentation and support from the forum is excellent and there are many robotics enthusiasts using the chips. Control for servos, steppers, ADCs etc are built in to the BASIC-like programming language as well as a host of other goodies. You can also simulate the circuit before you build, and do real-time debugging on a running controller. Look out for more PicAxe based projects from me.

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    104 Discussions

    Finally got around to building my own called "Terminal" The Haunted Mummy. Awesome build Andygadget. Love it.



    2 replies

    Hello please send me source code for Terminal" The Haunted Mummy send for my email edmilson@lseletro.com.br. thanks

    A like the solid thump and really good vibration you've got with yours.
    Are you using a motor or a solenoid for the knocker?
    (And ta for the mention at the end #;¬)

    Hilarious! Love it :D

    Hi Andy how is your scope coming along. Have you had a look at Admiral Aaron Ravensdales instructable? https://www.instructables.com/id/Poltergeist/. I have just spoted it/ His uses 2 piezo sounders, put still uses one like you did as a mic. Do you think there is a change in the 08m2's programing language that has an issue with changing it back to an output as he used a second piezo to play the sound while his code is very similar? I still would love to get this going with one piezo to cut the cost down so students can make this awesome instructable

    Thanks again for this great project

    ps Are you working on any other 08m2 inventions using this great new chip with touch capabilities and a bigger memory?

    Here is my version with the latest PicAxe 08M2 Chip.
    Thanks for your instruction AndyGadget...
    I do some changes in the speaker / microphone section and add a flash signal durin knock!

    Admiral Aaron Ravensdale

    Thanks Jessy.  It needs updating as the parts list appears to have disappeared at some point and there's a problem when using  the latest version of the microcontroller, but I'm on it.

    Hi I just finished my version of your poltergeist and use the 08m2 chip. I change the code a little and use a single microphone and a speaker. I also add a flash with works with the knock.
    I hope i found until next week some time to post it here. But you can see it still on my website http://www.steampunk-design.de/useite.php?Klopfgeist pls change into english language!


    I built a box "Don't Open Till Doomsday" based on the Outer Limits episode with the same name.I shorten the program just to do the knocking and change the port I/O.  Added a opamp to boost the signal from the piezo.  Works very well. Thanks for sharing. I still need to make "the creature" that lives inside using Sculpey III. Photos at this link.


    Does anyone know how to get this going with the new 08m2 chip, I have changed the names to c.4 etc and mic input but it does not work nothing happens? I have students that love making the knock box at my school but new chips wont work.

    7 replies

    It shouldn't be a problem - I thought the PE accepted the old pin syntax for the 08m2 as well as the new and the old code should have worked as well as your version.  I'm off to work now but will swap mine for a 08m2 later and investigate.
    It's great that you're using this as a school trainer.  That's what the PicAxe was primarily for.

    It does program the chip with the old code but the piezo does not respond. I changed the pin names and the input further down the code and does the same thing. I also tried it in second knock box with a bs270 mosfet and the mosfet got extremely hot you could smell it cooking, yet changing it back to the old chip it worked fine. Dont know if this information helps you with any problem solving. Thanks for your time

    Thanks for the extra information.
    What you describe is very strange.  I'll definitely look into it.  
    I didn't get a chance to try this tonight - Should do tomorrow though.

    I spent some time on this tonight and there is something strangely different with the 08m2.  I didn't get the transistor heating you were seeing, but I couldn't get it to respond to the piezo knocks.  If I manually took the input high it would only produce one knock no matter how many times I triggered it.  I'll continue at the weekend.  (Maybe it's haunted #;¬)

    Thanks for the time you are spending on this. I have been looking at different things. I added an led to the piezo and it flashes when the piezo is tapped each time, so it seems to pick up the knocks, but not record them. I dont know too much about programming but is the memory allocation different on the m2 chips and the m2 information notes mention some command replacements but I cannot see any in the script that needs changed. It also mentions peek commands but this means nothing to me (yet)

    thanks again

    The 08m2 has more memory for peek and poke, but the addresses I used in the original are part of that, so not the problem.  The weird thing is that it's not recording the knocks.  I can see the input on my 'scope (as you're doing with the LED) and the levels are there.  I'll get it sorted at the weekend - It's one of those annoying things which should work . . . but isn't.

    It looks as though the PIC the 08m2 is based on is a bit fussier when it comes to it's inputs (although the levels I'm seeing with a 'scope should be triggering it). A bit of signal conditioning is needed to get this working again, rather than the 'it works so I'll leave it as it is' approach I used initially. The code timings are also different between the 08m and 08m2 so the loops need adjusting. I'm working on this.

    A bit of tidying up in in order though.
    Add the lines :-
    LOW Knock
    LOW 1
    immediately after the declarations section, at the top of the man code.
    This will sort your FET heating problem and also grounds a pin which was floating as an input before. It would have overflowed the memory on the 08m. Also tie physical pin 4 (I3) of the chip to ground. 
    (The 'LOW knock' is a quick fix.  The gate should really be pulled down via 1K or so to keep the FET turned off when the pin is an input.)

    I'll let you know when I've sorted it.