Introduction: Back to the Future: Doc Brown's Mind Reading Helmet

Picture of Back to the Future: Doc Brown's Mind Reading Helmet

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!

Step 1: Gather Materials

Picture of 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

Picture of 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.

Step 3: Drill Holes and Add Conduit Grommets

Picture of Drill Holes and Add Conduit Grommets

The LED assemblies are attached to the helmet itself via lengths of dowel, recessed into the helmet. I used thirteen LED assemblies, one at the top, eight in a circle around the base of the helmet, and four in a circle halfway between.

First I drilled small pilot holes, then took the whole thing to the machine shop at work after hours, and used a large drill bit on the drill press to make holes that were just right for the conduit grommets.

The process of drilling these large holes kind of tore up some of the sheet metal and parts of the plastic helmet, but I was able to glue/epoxy everything back in place, and the grommets covered up most of the problem areas.

Step 4: Prep and Add Dowels

Picture of Prep and Add Dowels

The dowels were cut to a uniform 2-1/2" using my miter box. They were just a bit loose in the conduit grommets, so I added a couple of loops of electrical tape to the end of each. Finally, I put them in place and secured them all with epoxy.

Step 5: Cardboard Washers

Picture of Cardboard Washers

Using the toilet paper roll as the outside diameter and the plastic tube from a garden light as the inside diameter, I cut out several cardboard washers.

Step 6: Toilet Paper Tubes

Picture of Toilet Paper Tubes

Again using the miter box for uniformity, I cut off about an inch or so from thirteen cardboard toilet paper tubes. This gave me thirteen long and thirteen short, uniform tubes.

Each of the smaller tubes had one of the cardboard washers glued to it. These were all painted primer gray.

Finally, I added two small screws to each of the washers.

Step 7: Plastic Tubes

Picture of Plastic Tubes

The plastic tubes harvested from old solar garden lights would serve as the base of each LED housing. I cut each to length using the miter box, then painted them all a coppery color.

Step 8: Wire Stars

Picture of Wire Stars

I needed a four pointed wire star at the top of each LED housing, both for accuracy and for stability. Using a piece of scrap wood and some finishing nails, I built a simple jig, wrapped my solid core wire around it, and then cut them off. I added a dollop of hot glue to the spot I'd cut each star to hold it in one piece.

All the stars were then spray painted black.

Step 9: Building the Housings

Picture of Building the Housings

Each LED housing started with the reflector pressed into the painted tubing. Next I would attach the wire star with little dabs of hot glue, followed by the larger gray cardboard tubes, also attached to the wire star by hot glue. Last came the LED itself, with legs bent at 180 degrees and hot glued in place, emitter pointed down at the reflector. When it was all done, I put a bit of epoxy over each hot glue joint for a more permanent bond.

Step 10: Add the Housings to the Helmet

Picture of Add the Housings to the Helmet

Each of the short cardboard assemblies is now placed over the dowel, followed by the housing tube. Hot glue to hold it, then epoxy to make it permanent.

Step 11: Crossbeams

Picture of Crossbeams

Using strips of cardboard painted primer gray, I cut each crossbeam individually, then hot glued it in place. Time would prove these to be the most easily damaged parts of the helmet, I had to reglue several of them.

Step 12: Wire It for Power

Picture of Wire It for Power

The LEDs in this assembly are wired in parallel, with a single resistor in series. I played around with the resistance until I found one that gave me the brightness I wanted.

Each LED is wired up to the main switch and a 9-volt battery located at the back of the helmet. I wasn't too careful about where the wires lay, as the original had a cobbled together prototype look, particularly where the wires were concerned.

*** Note--take a look at the comments, ElectroFrank has made some interesting points about how to PROPERLY wire this sort of simple circuit for a more efficient use of the batteries involved. ***

Step 13: Rock It at the Halloween Party!

Picture of Rock It at the Halloween Party!

Or, as the case may be, make sure you and your kids are well illuminated when you're trick or treating.

Thanks for stopping by! This was my first instructable in quite a while, and I would love some feedback. Make sure to comment, follow, and favorite!


ElectroFrank (author)2014-05-30

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.

depotdevoid (author)ElectroFrank2014-05-30

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!

ElectroFrank (author)depotdevoid2014-05-30

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.

depotdevoid (author)ElectroFrank2014-05-31

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!

darnstadium (author)2017-03-08

Patent pending? figured out how to use fluorescent tube starters to build a home-made magnetometer that is 100* more sensitive than anything currently on the market. Catch: needs SDR chips but those are readily obtainable.

darnstadium (author)2017-03-08

Also relevant: I usually use JFETs as current limiters, less wasteful and you can fine tune the input voltage for lowest dissipation.

tobias.claren.9 (author)2016-06-14

Why "Mind Reading" Helmet?
Is there a source for this assertion?
It could also be "transcranial stimulation".

Transcranial Magnetic Stimulation, "TMS", or Transcranial Ultrasonic Stimulation (more exact).

Here a protoptype by DARPA:

could buy "capacitive micromachined ultrasonic transducers" ("CMUTs"),
and powering this helmet with amplifiers for seperate channels for each

And look here:

The "Thinking Cap" by "Giro Gearloose".
Perhaps, this helmet in BTTF was an allusion to Giro Gearloose.....

You could try to make a real working Version.....

tobias.claren.9 (author)2016-06-14

Why "Mind Reading" Helmet?
Is there a source for this assertion?
It could also be "transcranial stimulation".

Transcranial Magnetic Stimulation, "TMS", or Transcranial Ultrasonic Stimulation (more exact).

Here a protoptype by DARPA:

You could buy "capacitive micromachined ultrasonic transducers" ("CMUTs"), and powering this helmet with amplifiers for seperate channels for each CMUT.

And look here:

The "Thinking Cap" by "Giro Gearloose".
Perhaps, this helmet in BTTF was an allusion to Giro Gearloose.....

You could try to make a real working Version.....

banman11 (author)2015-10-22

very cool project.

Well done.

depotdevoid (author)banman112015-10-30

Thanks! I had a lot of fun building it!

weipertg (author)2015-08-28

Awesome hat. What purpose does the sheet metal serve? Can you do without? And do you have anymore solar housings? Thanks

Treasure Tabby (author)2014-05-26

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.

wilgubeast (author)depotdevoid2014-05-30


fixfireleo (author)2014-05-30

cool! i wonder if you could chrome the metal somehow so it would look even more like the one from the movie?

depotdevoid (author)fixfireleo2014-05-30

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!

ReOfSunshine (author)2014-05-29


mikeasaurus (author)2014-05-28

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?

depotdevoid (author)mikeasaurus2014-05-28

I absolutely did, and shouted, "Great Scott!" at every opportunity! Forgot to put a bandage on my forehead though.

craftclarity (author)2014-05-27

I'm impressed. Your attention to detail is impressive.

depotdevoid (author)craftclarity2014-05-27

Thanks! I have a lot of fun making these props as accurate as possible while building them largely out of junk.

5923r (author)2014-05-27


seamster (author)2014-05-26

Ha, very nice! I think you should add a permanent Doc-esque wig around the sides for the full effect.

depotdevoid (author)seamster2014-05-26

Yeah, couldn't find one I liked on short notice (this was cobbled together about three days before Haloween. Next time!

mrodriguez-enns (author)2014-05-25

This is beyond cool!

About This Instructable




Bio: depotdevoid is short for The Depot Devoid of Thought, the place where you go when you lose your train of thought and you're waiting ... More »
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