Costume Motor Controller In Detail
As I’ve mentioned in another post, last year’s costume was a Zombie Santa Snow Globe. There were a few problems with the snow globe and most of them stemmed from bad decisions, poor planning, and a complete lack of testing. Oh, and some near asphyxiation.
This year I’m taking my power and air requirements seriously and I started planning this about 3 months ago. I wanted a solution that could easily be adapted to future costumes and I think I’ve come up with one that will work.
The motor controller was purchased from Carl’s Electronics for about $25. The project box, pot knob, toggle switch, and rubber grommets came from the often cursed and over priced Radio Shack. The terminal lugs and orange cord (appropriate I though for Halloween) came from Home Depot.
Construction of the kit was straight forward with no surprises. I turned the POT around to the other side of the board so the shaft would stick through the lid. The only real difficulty I ran into was identifying the resistors. The colors and my old eyes didn’t want to play nice so I cheated by checking the values with an ohm meter.
I ran a few initial tests driving my 12V rechargeable leaf blower at various speeds and the mosfet’s heat sink got plenty warm. Not quite enough to burn me, but certainly hot enough to be uncomfortable. The temp didn’t change much after the first minute but I was afraid that once it’s enclosed in a box it wouldn’t be so happy. I solved the heat issues with a tiny muffin fan that I had liberated from an external cd-rom drive.
Mounting it all in the box was a bit kludgy but it works and I’m very happy with the outward appearance. There are only two screws holding the circuit board in, but it’s sandwiched between the lid and some internal ribs so it shouldn’t go anywhere. The zip tie is pulled tight around both cords for strain relief and the cords pass though a couple rubber grommets to cut down on chafing. I really should add a fuse on to the power line but haven’t taken the time yet. Maybe I’ll put an inline near the batteries just to be safe.
The batteries will be mounted in a backpack and the controller box will be tied to the strap within easy reach. This should let me carry more amp hours than last year and keep the weight of the batteries off the costume which caused some tilting problems in the snow globe.
The fan came from Bass Pro Shops and pushes 230 CFM at 4 amps. I’m pretty sure, but not yet positive that will keep my costume inflated this year. Liberal use of check valves in the construction should help. In this picture you’re looking at the inlet of the fan. I’m still unsure what to do about a finger guard, or if one is even necessary, but I’ll decide that later.
I’ll divulge the nature of my costume this weekend once I start gluing the vinyl together and get an idea of just how I’m going to make it. Until then I’ll be testing the endurance of the motor controller and fan with two 12VDC drill batteries. I estimate that it will run for about an hour at full power or over 1.5 hours at half power.
