A few years back I decided to make an artificial pumpkin to save on the carving, to have something that kept without rotting too early and more importantly to have a bigger one than the shops stock.


To achieve that I got a large refuse sack and filled it with old sheets and bound it with Sellotape to get the basic shape of a pumpkin, complete with the bulging lobes. It then got covered with layer after layer of newspaper and PVC glue. Some raised features got added around the mouth, eyes and to make the stalk using various dry-wall fillers, glue and tissue. The whole thing got a good paint, shading and a final protective lacquer coat. The teeth were made using a material called Fimo - a modelling putty that sets hard once baked in the oven. Once complete he got named Peter and here he is.


{gallery} My Gallery Title

The first year Peter sat on the windowsill looking out with a PWM light flickering away inside; and that looked good. The next year Pete replaced my head for the walk around the houses! This year Peter wants to be on the internet so I've agreed and am writing this blog on his behalf ( come on, he's a paper mache head, so he needs some help). Rather than enter Pete into the sharethescare competition with his PWM lighting, I have decided to upgrade him to become animatronic.


This is what I plan over the next 2-3 weeks:


Head Turning

Peter is going to get a geared stepper motor turntable allowing him to move from plus and minus ninety degrees. In fact I've kind of built that alreadyMy First Stepper Motor and this will be controlled from an Arduino Uno (the one that Element 14 kindly sent to me earlier this year by Element14 Project14 | The Birthday Special: Arduino Projects for Arduino Day! ).

{gallery} Motor


Movement Sense

Adding movement sensing would give that scare factor. I was looking at Ultrasonic detection and then I was also taken with the 10GHz and 24GHz radar modules that are quite affordable now. What put me off those was they seemed to output quite a high power and I wouldn't want to damage any inquisitive eyeballs that decided to take a close look. Instead I have opted for a small PIR unit.



Pete is going to get some animatronic eyes. I planned to use Oasis florists foam for making these but I left the pieces I was thinking of outside and they were completely waterlogged. I'm going to look for a 4" diameter ball and will paper mache that to make his peepers. I will try and make them transparent so I can do some back lighting. They will be slewed in azimuth only using a standard modelling servo (again driven from the Arduino).



He's getting a brain too (albeit an Arduino Uno one ) so he can work out when he wants to scare any visitors. I could add the new Arduino MKR1010 I bought and therefore control him via WiFi but he'll likely be autonomous anyway.


The Setup

I plan to run him at low voltage for safety. If it is a dry night Pete will be getting a place outside, but if it is raining he has muttered something about "de-laminating his newsprint" (whatever that means) and would rather stay indoors.




Update: 12 OCT 2018

My SR-505 PIR module appears to be broken. I supplied it with +5v to the positive pin, Ov to the negative pin and monitored the output pin on my 'scope, which shows a 2.6v DC output. Nothing changes when I approach the device, move a hand over it or look into it. Looking at the circuit schematic I found here there is a series resistor in the output. If the device can drive a BJT as per the diagrams then it should have a changing output voltage. I tried a 4.7k pull up though, just in case and still nothing. I'll give it a resolder later in case there is a dry joint...