I love the Back to the Future series. It was definitely a staple growing up, and for Halloween I wanted a costume based on it.
Now, I'm no Marty McFly, I'm definitely more the Doc Brown type. I don't look anything like him, but with some awesome headgear, I knew I'd be set!
Remove these ads by
Signing UpStep 1: Gather Materials
For this project, I used:
- an old bike helmet
- a length of 5/8" dowel
- some conduit grommets that (almost) matched the dowel
- reflectors and stands from some solar garden lights
- some old solid (non-braided) wire
- a switch
- a 9-volt battery
- one resistor
- a bunch of yellow-orange LEDs
- some speaker wire
- a bit of sheet metal
- black, grey, and copper spraypaint
- leftover cardboard from cereal boxes
- a few cardboard toilet paper tubes
- some random screws
This was one of those nice projects I like doing where I was able to repurpose nearly everything I needed from something I already had lying aroudn the shop. the only things I had to buy were the helmet and the conduit grommets.
Step 2: Prep the Helmet and add Sheet Metal
First off, clean all that garbage off the helmet! I had to take out the foam comfort strips too because I have a giant freak head.
Next, cut a strip of sheet metal about 1 or 1-1/2" wide. I used a hack saw and my miter box to keep it uniform.
Make an X across the top, and then wrap the whole base of the helmet. My usual procedure of tacking it in place with hot glue, followed by overnight with epoxy worked beautifully.
Go Pro Today »
We're Hiring! »
Your circuit wastes the vast majority of your battery's energy in the resistor.
Batteries are expensive. Resistors are very cheap.
The attached circuit will give you massively more light for much longer from your 9V battery.
Cool, thanks for the advice! I was going for quick-n-dirty, and I use rechargeable 9-volts, so I didn't really think about efficiency. Flagged this one to the top of the list!
The principle is this: reckon about 25mA current for regular small LEDs.
For red/green/yellow/orange, reckon 2V across each of the four LEDs, then the rest of the 9V must go across the resistor.
So in the example in the diagram, 4 x 2V = 8V, so the resistor should be: 1V / 25mA = 40 Ohms (I put 47 because of availability)
(But have a little more or less to choose your brightness).
For two white or blue LEDs, reckon 3.3V across each LED, so 2 x 3.3V = 6.6V, so 2.4V / 25mA = (about) 100 Ohms
Three white or blue LEDs across a 9V battery will be underpowered, but provide a gentle glow for a long time.
Awesome, thanks again! This is "back of the envelope" stuff that I've only ever messed with peripherally, thanks for real world examples of it. I'll make a note in step 12 to take a look at this stuff. Thank you for taking an interest in my creation!
Oh what fun!
Next you should make the Thinking cap from Hitchhiker's guide to the galaxy movie. It looks a bit like a lemon squeezer. Hilariously fun! :D
I'd forgotten about that! The Hitchhiker's Guide would be a great source for all sorts of costumes. I might try my hand at Marvin the Paranoid Android from the 1980s TV series.
+1.
cool! i wonder if you could chrome the metal somehow so it would look even more like the one from the movie?
If I'd used a silver spray paint instead of primer gray it would have looked more accurate. I was trying to use stuff I had on hand though, so I went with the primer. Definitely regretted that after the fact, silver would have looked way better!
Great Scot!!
I remember you talking about this a while ago, glad you posted it. Did you act all spacy during the party like Doc did when he answered the door wearing this?
I absolutely did, and shouted, "Great Scott!" at every opportunity! Forgot to put a bandage on my forehead though.
I'm impressed. Your attention to detail is impressive.
Thanks! I have a lot of fun making these props as accurate as possible while building them largely out of junk.
omg.
Ha, very nice! I think you should add a permanent Doc-esque wig around the sides for the full effect.
Yeah, couldn't find one I liked on short notice (this was cobbled together about three days before Haloween. Next time!