I made a mounting plate and piston rod end hinge for the piston I'm going to open the coffin lid with.


My Lego lash up suggested to me that the mechanics were sound, but I made a full size version up to test the theory:







Here's a video of it in action, I was running it at quite low pressure (around 60psi) so there is plenty of room for improvement in the speed department.

Rats nest

I've now got all the schematic symbols sorted out and I'm ready to start designing the PCB. This basically involves placing copper tracks in place of the links between components on the PCB. I start out with the rats nest below and move/conenct
components until they are all connected as required ans sensibly positioned.

It's alive..well sort of

The small pneumatic cylinder I ordered from Ebay arrived today.





I'm going to use this to open the coffin lid. It has a 125mm stroke. As I need to make sure the mechanics will work I knocked up a simulation with some old Lego technic that has pneumatics!

Here is the lash up:



And a video of it in action. The red plate is the coffin lid!

Revised Design

I decided that I needed to add some LEDs to show the ouput status of each channel, and some switches to allow the inputs to be stimulated.

Now to check all the component footprints before I design the PCB.

Here's the new schematic:

Interface Design

I finished the PC parallel port schematic. Just need to double check it then I have all the fun of finding the appropriate footprints for the components I wish to use. I think I'm going to go for a combination of surface mount and through hole components as I already have through hole stock of some of the bits.

Halloween beginnings

I've decided to start blogging some of the stuff I do in my spare time. First off I want to blog the development of a new Halloween show I'm doing for the house for 2009.

Last year I put on a show involving gravestones, lightning and smoke. This year I'm going to add
a coffin with door that opens as trick or treaters approach, and maybe put a skeleton that rises out of it.

I plan to develop an interface board to allow me to detect voltages and switch relays from the PC
parallel port as this is an easy port to connect to the outside world. The mechanics will be operated with pneumatics.

I started the ball rolling last night buy starting the interface board design and ordered some 12V solenoid valves:



And a pneumatic cylinder to raise the dead with:


This has a 250mm stroke so I'm hoping that with sufficient pressure it will raise a skeleton a la Nosferatu.