MYOD 'BTTF' Time Machine:
Flux Capacitor
Last updated: January 29, 2003 3:15 PM (CST)

How To Build Your Own Darn
Time Machine.
Flux Capacitor Information

Standard Liability Disclaimer: Although I have used these instructions in making my own props,
I accept NO RESPONSIBILITY if you ruin your own components or other parts
using these instructions. These techniques work for me, they might not work for you.
These instructions are worth exactly what you paid for them.

I knew you'd visit this page first! Most people do. ^_^

The 'Flux Capacitor' is the device in the film that makes time travel possible.
In reality it's a nifty lighted deal that impresses women. Okay, not really, but it's
still a nifty lighted deal.

PART 1: The Box

Screen capture from the film. Image (c) 2003 by Universal Studios

The BIGGEST SECRET about the flux Capacitor has been the box that contains the
lighted deal. The box...

Image (c) 2003 Gary Weaver II a fiberglass electrical enclosure box manufactured by Stahlin.
Stahlin J1210HPL with a custom 9x7 window.
The size is approximately
11.43" Wide x 13.56" tall (11 x 14?).

The model you want if you have more money than brains (or access to power tools
is the Stahlin J1210HPLW, which has the window already cut and installed. However,
the cost is about double.

You might be able to find an enclosure at

Approximate Cost: $80.00

The box color currently available is "Glacier Grey." The original box, by all indications, is
actually a slightly darker "Battleship grey" color and is no longer available. However, this is close enough unless
you want to repaint the box yourself.

Now this version (the $80.00 one) of the box does NOT have the window cut in it.
Stahlin will custom cut and install for you a window and gasket, (Identical to the one pictured above)
but the cost jumps up to like $160.00 a box, and there appears to be a 3 box minimum order!

A cheaper alternative is to purchase one of the clear PC window kits that allow you to see
the insides of your computer.

These window kits with rubber gasket material are readily available
from CompUSA at (oddly enough)...

Approximate cost: $15.00.


Image (c) 2003 Gary Weaver II

The obvious exterior wires are actually spark plug wires. The elbow is red in color, the wire yellow.
Apparently wires similar to these are still available. They are a performance spark plug wire, used in
street rods and other 'performance' cars. If you're on a budget, I suppose you could use a commonly
available set of stock sparkplug wires. Usually these have red or black 'elbows' and blue or grey wires.
The screen used ones were a red color elbow, with the yellow wires.

Someone told me that a company by the name of Accel manufactures a yellow/red combination that you cut
to the appropriate length and assemble. This appears, as already stated, to be a common 'performance'
accessory and are relatively easy to find. The person also looked at several other wire packages, and several do
indeed have red boots, but it's a more dusky red (like a pencil-eraser-red). The prop item certainly looks
like the flared coil end, and not a plug or distributor cap end. They also checked several types of cables
and the mouth / open end of the coil boot measured 7/8"-1" in diameter.

Jeremy also said...

I also found that spark plug cable (especially 8mm) is VERY hard to bend and is also unforgiving.
I am not sure what had to occur for the screen used wires to stay in place, but I had a thought.
If you can locate the accurate rubber boots for the ends, they make guitar cables in yellow.
It is a neon yellow color, but it is flexible. As soon as I get it in I will let you know
how it works out and looks.

You may be able to locate "screen accurate" spark plug caps from Skycraft

Approximate cost: $60.00 for a set of 8 + coil wire


Some people think that the lighted areas of the F.C. are clear plastic tubing, and many people use
that item in this section. Well kids, that's not 100% movie accurate.
I _think_ this was a screen capture from the film, so Image (c) 2003 the filmmakers.

Screen capture from the film, Image (c) 2003 the filmmakers.

Big Secret #2: the glass deals are...

...expensive, er, hard to find, um, they're actually...

High Voltage Relays. Torr tmr-9a (2) and Torr TVS-1 (1)

Similar item, but not 100% accurate to the film used version. Image found online someplace. Owner unknown.

Another similar item, not 100% accurate, but close. Image (c) 2003 Gary Weaver II

The glass part is shaped like a 'T' with the long section usually down through the
center of the metal part that activates the relay. I haven't been able to identify the actual model
of the relay yet, but I've seen several that share the common shape. The glass part of the relay consists
of a vacuume tube, so most of this style of relay are no longer in use today. I'm considering having these
cast in clear resin, which would obviously make them easier to find. ^_^

Jeremy said...
The bases (that the vaccume tube sits in) are 2 1/16" in diameter with a 9/16" hole in the center.
They are 1 1/16" high.

Pricing varies greatly and since the items are no longer produced, it's strictly a
price driven soley by market demand.
Approximate cost: $20-200.00


Another similar item, not 100% accurate, but close. Image (c) 2003 Gary Weaver II

This is another part commonly substituted by prop makers for clear plastic/vinyl tubing. In reality it was a
translucent acrylic block. It appears to be flat on top and bottom, and sloping to the center.
This item near as I can tell was custom fabricated. It wouldn't be overly difficult to build something similar
using thick acrylic or plexiglass block. The sides appear to be painted.

Gary's final version with all the correct parts. Image (c) 2003 Gary Weaver II

Gary's final version with all the correct parts. Image (c) 2003 Gary Weaver II Screen capture of correct parts. Image (c) 2003 Universal Studios

I received an e-mail from fellow BTTF nut and prop guy Jeremy and he said...

I have some information on the acrylic blocks. I used 1/2" acrylic block,
although screen shots show the width to apparently be 3/8". Either one will
work... the tubes mask the 1/2" no problem, but the 3/8" may be more screen
accurate. The ones I used are cut at 2 1/2" long at the top by 3 1/8" at the
bottom and are 1 1/16" high. The resulting angle will be 60 degrees in
pitch, but as long as the dimensions of the other ends are paid attention
to, the 60 degrees will come automatically at the other end.

If anyone has additional information on this aspect, please E-mail Me.
If you wish to remain anonymous that's not a problem. ^_^


So, now you have all your parts and you want to light the thing. Honestly, I haven't delved too deeply into
this particular aspect yet myself. However, you'll need either some high intensity LEDs or incandescent
bulbs (as were used in the original prop) to illuminate the works.
All the components will be attached to a surface inside the box, and generally not to the actual box itself.
This surface (board) will need to have holes drilled into it to run your lighting through, as well as the
wire ends of the (cosmetic) spark plug wires.

There's some minor confusion as to how many lights there were in the F.C. To many people it appears there
are 3 lights. There are a few others who claim there are 4 lights. Someone close to the source
has stated that there were only 3 lights.
Lighting layout diagram, original 3 light version. Image (c) 2003 Rook's Castle
GWII used 3 LEDs in the center of his F.C. This produces a very bright center when illuminated, much like
that of the F.C. seen in the film. If you choose you could of course only use one LED.

In the 3 LED option, your LEDs would be placed under the base of the glass 'T', midway down the acrylic piece
and finally in the center.

It should be noted that in the screen used prop there was no center lamps in the middle where the
three acrylic blocks come togeather.
Another FC builder has shed some 'light' on his own observations regarding the FC construction.

First of all, scrap the seemingly popular center strobe light idea. The bright light that is emitted from
the Flux Capacitor is a constant steady light. Watch BTTF 1 when Marty is about to go to 1955 (I think it is also
visible during Einstein's trip 1 minute into the future).

I have to agree. After re-watching BTTF1 It appears (obviously) that there are only 3 lights, and those
are located evenly spaced under the acrylic blocks, and all of them are before the downward slope.

The Flux Capacitor gets very bright in the center and
around the edges and stays that way until the vehicle arrives at its destination. The bright light that comes from
under the tubes I attribute to internal reflection inside the acrylic blocks from the center and/or outer light
sources. So you really only need worry about lighting the center and the edges.

Secondly, mask the LED's with acrylic block. There are some replicas I have seen out there that just have LED's
laying inside clear tubes. When the LED's are not activated, it is clearly obvious that they are there, which is
not true to the screen used version, and IMHO looks cheap. You want to create the illusion that the light
originates from one end of the tube and is shot down towards the other.

Lastly, the pulse pattern for the flux is 1,2,3,1,2,3,etc. I know some people claim that at some points it
goes from 1 to 3 but I think that the circuit responsible for firing the second light was a bit flaky,
so when it didnt fire it jumped to 3. Whatever the reason, the steady 1,2,3 pattern is the way I think
it was intended to be.

Those are my main criticisms on the replicas. That and the rubber tube idea, but with the screen used
parts for those being few and far between, I can't be too hard on people there.

3 LED center. (c) 2003 Gary Weaver II

Gary's Finished F.C. Image (c) 2003 Gary Weaver II

Gary's Finished F.C. Image (c) 2003 Gary Weaver II

Another wrinkle...

Now that you're all set to wire it up, there appears to be yet ANOTHER set of lights inside the F.C.
These lights appear to be a general illumination light. If you look at GWII's Flux Capacitor, he has
at least three additional lamps in the box, near the outside edges that illuminate parts of the 'Y' shaped mechanics.
If you look closely at the movie version, you can barely make out what looks like a small lighting fixture
in the lower left corner, where it would be hidden from a strait forward camera shot.

In the illuminated detail shot you get the impression of at least 3 - 4 seperate lighting elements in the box,
as a seperate effect from the chasing lights of the F.C.

4 seperate lights? Screen Capture from film. (c) 2003 Universal Studios

Mystery object. Screen Capture from film. (c) 2003 Universal Studios

Another lighting hole layout with Illumination Lights. (c) 2003 Rook's Castle

In the diagram, the holes for the GIL's, the high voltage bases and the plug wire holes are all in
line with each other. The wire holes for the top 2 high voltage units are in line with the center LEDs.
In the diagram the lower right plug wire hole is out too far. It _should_ be in line with the other holes.
It's all just a suggestion anyway. ^_-

And here's a couple more, somewhat accurate diagrams...
3 lights, 'screen accurate' layout. (c) 2003 Rook's Castle

3 lights, 'screen accurate' layout. (c) 2003 Rook's Castle

Jeremy said...

The flux bands are spaced at an angle of 130 degrees in relation to the left and right
portions of the Y, leaving 100 degrees at the top. Mine will most likely be more around
the 125 degree mark, but the 130 degrees was taken from a head on screen shot using a protractor.


I haven't tested these schematics out yet for myself, so try them
at your own risk. I won't be held responsibe if your burn your car up or
brown out the greater Dallas/Fort Worth area by using them. ^_^

I don't know who came up with this diagram. If it's you, let me know.

Here's a wiring diagram SuperMatty at the BTTF boards made up for wiring the FC lighting elements.
I haven't tried it out yet, so I don't know how well it works.
The creator of this diagram also let me know that it's designed to use low power LEDs and NOT
incandescent bulbs unless you connect transistors at the outputs, or use a higher output register.

Jeremy also posted his own wiring diagram...

Click image to enlarge.

The only other considerations would be to modify the circut with a variable timed pulse,
so the "faster" you go, the faster the FC will flash. And while you're modding, you'll
want to add a "full active" mode, where all the lights are lit when the FC is engaged and you're
"traveling through time."

There's also a little more FC info on the Internal Components page.
That's all I have for the moment on this item. If there's innacuracies or further information you'd
care to share, please let me know. If you so choose,
you'll be listed as an anonymous resource. If you want credit, I can do that too. ^_^


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