Wednesday, October 12, 2016

D-walker build part 5 - Electronics

The real and fake electronics in D-Walker.  These parts used an excessive amount of scavenged parts, so I'll try to save all that source information for a big list at the end.

The "cockpit" of D-Walker is the most detailed part of the costume, even though the rider is about the only person who can really get a good look at it.  That may be for the best, though, because it is also the least accurate part.  Compare the above to the source below:

The proportions just wouldn't have worked with how I wanted to build it.  The real D-Walker is larger than mine, and that big rectangular shape would hinder my legs.  The grips are of suitable size, but I couldn't position them far enough apart without scaling the entire build up.  I also had some electronics from the 80's that I thought would look good, even if they weren't accurate.  I condensed the layout a little to make it work with the scale and materials available.

Anyway, D-Walker has a few simple electronics in it.  In the head it has two LEDs and an exhaust fan, as well as the GoPro Hero 3.  There is a pair of fog lights on the front.  There are some lights and a semi-functional attitude sensor on what we'll call the dashboard (the part with the large blue circle).  The center console has an LED readout of volts and amps, and hidden behind it are a pair of PC fans that blow on the rider's wrists.  The right grip holds the main power switch, and a sub-power switch bank is located to the right of the center console.  At the con, I hid my phone deep in the cockpit using a magnetic mount so I could control the GoPro and do other phone things while appearing to be fiddling with integrated controls instead of my phone.  The four buttons on the sub-power panel control the head lights, head fan, fog lights, and rider fans.

The knobs on the power supply panel are just for show.  Why would a rider need to adjust the current and voltage?  Maybe this is a prototype D-Walker that needs tuning, or maybe it needs to be adjusted when using something like the H-Discharger.  The three switches in front of the right grip are for show because Alan Tudyk loves flipping magic switches.  The black ignition button on the right grip is not currently used, but the plan was to have that be the trigger for whatever weapon is installed on DW's left.  The wiring exists, but I didn't build any weapons.

The red stripes are supposed to remind you to keep your fingers out of the fans.  Sorry for bad lighting.

The above photo is the center console panel, opened for access to the battery pack and power display.  The rider cooling fans make up the left and right walls of this compartment.  A 12V battery pack, modified to make 9 volts, is secured by a twisty wire tie and can be connected/disconnected without removing it.  A length of coat hanger loosely zip tied to the panel acts as a kick stand to hold it open.  A magnet on the lower left holds the panel closed, provides a secure base for the kickstand, and also holds a hex wrench that is needed to remove the head and arm.  I removed the printed circuit boards behind the power supply's display and replaced it with my own self-contained LED display.

Nearly everything about the center console is improvised.  I had already made the frame without knowing exactly how I would build this area, so when I started adding pieces, I just had to make it up as I went along.  While figuring out how to mount the power supply panel, I realized it could be hinged instead of fixed.  The fans were added because they happened to be the perfect size and I thought it was cool, even if they don't actually provide much cooling.  The panel kept slamming shut whenever I bumped it, so I added the kickstand.  I added the LED display when I realized a name tag from my portal gun project would fit in the space and could easily be programmed with whatever I wanted.

Dashboard.  The markings on the blue screen are meaningless now, but they look cool.

The dashboard consists of a green main power light, a red warning light, a DC milliamps meter, an attitude sensor, and some non-functioning buttons and knobs.  The warning light is just a reflector - it's shining here because I used a flash.  The main power light and sensor come on with the main power switch.

An attitude sensor displays a vehicle's pitch and roll as compared to the horizon - this is generally only used in things that fly, and is probably called something else in that application.  In MGSV, the green circle might be a radar or something.  In my D-Walker, however, it came to be an attitude sensor because I was just trying to come up with an interesting way to use that blue screen.  The white LED beneath the plastic screen is affixed to a metal rod with a weight on the bottom, suspended by a water balloon (yes, really).  The water balloon, being nice and flexible, lets the rod sway all over the place.  The rod came out of a printer and has a little groove in it where the water balloon ties around it, keeping it from slipping loose.  The weight, a brass fitting, keeps the rod pointed towards the ground, with an inverse effect on the LED.  You know what, just observe this gif:

A textbook(?) example of a cheap cosplay trick.

I didn't use any relays, resistors or anything complicated in these electronics.  I just made sure all of the LEDs were pre-wired for 9 volts.  The PC fans and all of the switches (including the stock motorcycle controls) are made for 12 volts, but will work just fine with 9V (the fans just spin a little slower at lower voltages).  To convert the 12V battery supply to 9V, I modified the connecting bits to exclude two of the eight AA battery slots.  Eight AAs at 1.5V each = 12V; six AAs = 9V.  I did this because I already had the 12V holder.

Speaking of things I already had, below is a list of every little piece unique to the electronics, and where I got them.  I got a lot of cool stuff from an old IT firm that closed down about a week after I started building DW's frame.  They gave everything away on Craigslist for free, and it was PACKED with stuff.  I spent 5 hours there and left with all kinds of other things like a 40-piece tap and die kit, a Virtual Boy, a strobe light, a PS1 DDR pad, electronics and programming study books, power strips, plastic containers, and so on.  If I wanted it, I could have taken thousands and thousands of dollars worth of professional electronics, but it was all too huge and heavy to bother with.  I'll refer to this source as "CL IT".

-Instek power supply - CL IT
-Oscilloscope (donor for blue screen) - CL IT
-Non-functioning dashboard bulb - Oscilloscope
-Fuse holder - Oscilloscope
-DC milliamp meter - CL IT
-Specialty screws for milliamp meter - removed from broken multimeter
-Non-functioning dashboard knob - removed from broken multimeter
-Non-functioning dashboard button - power switch for broken Surefire flashlight, from a friend
-Nametag LED display - portal gun project
-Round SPST switches - portal gun project
-Green LED - portal gun project
-Green lens for LED - pried out of slow cooker on the side of the road
-White LEDs - MIDA project
-Donut magnet - MIDA project
-Coat hanger - closet, I'm sure I didn't buy it
-PC fans - CL IT
-12V battery holder - Warlock project
-Red reflector bolt - came with motorcycle, formerly used to affix license plate
-Printer rod - a broken printer that became more broken, from old retail job
-Grenade-patterned water balloon - I just have water balloons okay
-Brass fitting - from old solar job, I was going to use it to make a mock shotgun shell
-Yellow vinyl (fog lights) - scraps from label printer at old solar job
-Clear acrylic (fog lights) - old retail job
-Foil tape (fog lights) - old retail job
-Wire thingy (right of dashboard) - CL IT
-Hinges - Found in toolbox, not sure of origin
-Magnetic cellphone mount - borrowed from girlfriend's car
-All wire connectors - from back when I installed too many electronic things in my old car
-3 magic DPST switches - CL IT

That list surely means next to nothing to you, but as I mentioned, it's significant to me because lots of it is leftover from old projects and random parts hoarding.  The point is, I built all of that at almost no cost!*

*Not including money already spent on other projects...

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