Tuesday, 21 June 2016

Flamethrower footage

Bound to be the most entertaining flamethrower post to date, all the footage I have so far of me firing the flamethrower. Enough squirting water and pressure testing, lets get to the real deal! 
First if you are impatient, here are a couple short GIFs:

Those GIFs and the next couple of videos are of version 1 of the flamethrower, with the longer hose and primitive nozzle. This video is the same as the first GIF but a bit better quality if you want to see the flame better:
The next two are fairly short, first in slow mo, second in non slow mo. Shot during the same tank of fuel as the first one:

And if you are a bit more patient, here is one continuous clip of the whole tank being shot off, taken at the same time as the other shots, but with slow mo in different places and as one continuous shot:
This next one is footage taken with the camera mounted to the wand during the daytime, with the upgraded tip. Im shooting a bit into the wind on this one. (A screenshot of one part of this video is where I got the picture for the top of my blog) 
And then these last three are different perspectives of the same night shot. First, one taken from a ways away (Probably my least favourite)
One taken from the POV cam on the wand:
And my favourite, mostly because of the dialogue, one shot from up close by a friend:
Well there it is! All the footage I have of the flamethrower being fired. I probably won't get anymore till it cools down again and we get some rain due to the high forest fire risk, but when that time comes, I can't wait to test out the shorter wand hose and shorter propellant tank mount. Hope you enjoyed it!

Monday, 20 June 2016

Flamethrower details

In a previous post, I mentioned that I had been building a flamethrower on and off over the last year or so, and at the time of the post I had not completed it yet. I was also a little sparse on the details and pictures. Well anyways I have long since gotten it finished and actually revised the design slightly. So here are a few more details and pictures and whatnot of it all.
First off is this one. This shows most of the components of the flamethrower before it was assembled:
A quick picture of the tank as it is holding its very first pressure test:
And a closeup of the bottom showing where I drilled and tapped the bulkhead fitting into the tank.
Getting that hole was no easy task. I think I ended up turning a floor mounted drill presses table 90 degrees to what it normally is and using about 7 ratchet straps to secure it to the table at the right spot. But I got it made. You can see where I spent a bit of time with a sander, smoothing out any inconsistancies in the metal and removing all the paint where the o-ring seals.
Here you can see detail of both the torch mount, custom made from some scrap sheet metal, and the device that I made to prevent the fitting from turning in the bottom of the tank or coming loose. Hydraulic hose does not have any torsion at all to it. If you twist one end, the other one is twisting as well. I was worried that if I accidentally twisted the gun handle or whatever, my fitting would start to spin out of the tank or rub the o ring or any number of other bad things. So I took a piece of nice thick aluminum I had laying around, roughtly cut it to fit the bottom of the tank and extend out one side. Then I painstaikingly drilled and filed and drilled and filed and drilled and filed some more until I had a perfect hexagon that fit right over the fitting. I drilled a hole just on the side of the tank and secured a bolt thru it. Then hose clamped the bolt to the tank in exactly that position, effectively eliminating any possible movement.
Heres a picture of the flamethrower all completed and waiting to be used. In this shot I have a HPA tank hooked up instead of a CO2 tank because I believe I was again doing some water testing.
And this is how I store it. The barrel unthreads from the gun handle for ease of storage, the valve unthreads from the the top of the tank and the paintball remote line has a quick disconnect on it. 
I mentioned in my previous post that the spray coming from the wand was dissapointing in range, and so before I even tested it with fuel instead of water, I went to the hardware store and purchased several 1/4" caps to thread on the end of the barrel and drill different sized holes in to see which was the most effective.
I ended up using one with a hole this size:
It did work fairly well, I have some video that I will post later showing the flamethrower firing using this tip, but I found that as it shot out, the harsh reduction in size caused the water or fuel to spray out and atomize more quickly rather than coming out in a stream as is more beneficial to a flamethrower. Nonetheless it did work and produced some impressive flame, it just needed to be improved.
Princess Auto came to the rescue with a 1/4"x1/8" reducing coupling and a 1/8" small nipple. Both designed to be used in hydraulic systems and therefore rated to 5000PSI or so. The 1/8" nipple is a fair amount smaller inside due to the thick walls needed to contain such pressure and has nicely beveled ends on both ends that cause a much smoother transition for the fluid and therefore more stream and less spray. The smaller ID means less fuel flowing thru, and therefore perhaps slightly smaller flame but longer lasting. I can always drill it out if I find myself needing more flow. Here are a couple of pictures of the upgraded nozzle:
Gotta have the first person camera to capture all the fire coming out of this thing, so I cobbled together a mount from PVC and pipe clamps. This is the only piece on this whole build that is just kludged together without much care. Its a non critical part, and I wanted it to be easily customizable.
Here's what the buisness end looks like. I think it looks kinda threatening personally :)
And for the final picture of the day, here it is as it is sitting right now. The other two modifications that you can see are the shorter line running from the tank to the gun handle and the shorter propellant tank assembly.
When I was first designing and building my flamethrower I wasn't totally sure how long of a hose I would need between the backpack tank and the gun handle, and because I didn't want to come up short, I bought and used a 6' hose. Which did indeed work, as you will be able to see from the videos of it in action, but it was not optimal. First of all, I am a tall guy and the hose hung down and almost dragged on the ground, not very practical. But more importantly, the longer the hose the more line pressure loss you have due to friction and other things. I'm sure if you asked an engineer, they would be able to tell you exactly why. I just know that as short as possible is better. So having some practical experence under my belt, I settled on a length of 3' for my new hose. Its just about the perfect mix of length for manuverability, without being too long and having too much line loss. Also hangs to a much more reasonable height above the ground. The second mod also has to do with simplification and  line loss. The paintball remote line was quite long, and had the quick disconnect fitting on it. I already covered line loss, and the QD was a little finnicky. Needed to be presurized and then wiggled around to seal properly. And having to hose clamp the tank to the fuel tank and undo it every time you needed to change tanks got old fast. All those problems were solved by just buying a paintball ASA (the thing you screw onto the top of a paintball tank and just connecting it directly to the CGA346 adapter that threads into the valve. Less line loss, no finnicky o rings, and easy bottle changes.

To end this post off, here are the videos that I took while pressure testing once all the upgrades had been made. First one is pressuring it up and describing the modifications, second is from the first person camera showing the upgraded spray pattern. Enjoy!

Wheelchair hacking part 2 (running under RC now)

Got home from work yesterday and promptly drove the wheelchair over beside the kitchen table and loaded it up with my laptop, oscilloscope, couple multimeters, notepad and all the other random stuff you need for a bit of hardware hacking:
I don't have any proper oscilloscope probes, so I just cut a BNC patch cable in half and then soldered a couple twisted pairs from a CAT5 cable to the ends. I'm not using them for any really sensitive low voltage applications or high frequency stuff so no sheilding and whatnot is totally fine.
In my previous research I found a couple of sites that have the pinout and some other data on either the joystick that came with the wheelchair, so figuring out which wires are what was pretty easy. (Ill post a list of the links I found helpful in my wanderings at the end of this post)  I hooked one of the two outputs from both the X and Y axes to the oscilloscope and flicked her on:
Everything seemed in order, it was working just as expected. I also realized that my oscilloscope can use the two channels as an X/Y plotter. Here is a video of what that looks like. Note that the joystick has a circular range of motion:
With that done, I turned my attention to the Arduino. Got some really basic code up and running that takes the signals from an RC transmitter and maps them to values that the DACs accept and then sends it to them. The DACs output a voltage in proportion to the transmitter's joystick. Heres a video of that one. Note that the Tx has a square range of motion. I wasn't sure how that was going to affect everything but it turned out fine:
Now that I knew the signals that I needed to emulate, I just spent a bit of time with the oscilloscope, one channel hooked up to the original joystick and one channel hooked up to the DAC's output, making sure I ended up always inside the original joystick's envelope for the X and Y axes. It would have been nice to have a 4 channel scope while I was doing that, but I made do. Once I had a good match from the RC stick to the original joystick, I shut everything off, disconnected the direction wires from the joystick (Left it with power and the center signal because the controller board needs to see that.) and connected them to the DACs.
I didn't want to just put both inputs from each channel together on the same output from the DAC because I assumed (and read elsewhere on the net) that the control board has some logic that detects that and locks out. So all I did was connect the DAC output to the anode of two diodes, and one channel to each of the cathode. Aside from the voltage drop across the diodes that made me run thru the whole process of connecting the scope up and matching the signals again, this has been working perfectly and only requires me use one DAC for steering and one for throttle.
Here it is all connected and spread out on the table:
And transfered over to the top of the chair:
Because I didn't want over a hundred pounds of metal and plastic putting a hole in my house from going haywire, I gave it a quick test with the clutches disengaged on the chair:
That went so well I engaged the clutches and drove it around the kitchen a little:
But wheelchairs, and this whole project, were designed to be driven outside not inside! So I drove it down the sidewalk to the local park (by now it was past midnight, so the lighting was not so great, fortunately the park has some streetlamps in the parking lot.) and put it thru its paces:
Once I got back home I just started cleaning the wiring up a bit. I routed the joystick connector outside the joystick case, made a little cover for the hole out of some sheet metal and hot glued in all in place. Hot glue is great cause its pretty strong and is waterproof. So once I got the control box screwed back together, it regained its water resistant status:
Tidied the wiring sitting on the top of the wheelchair up a bit:
And heres a closeup of the electronics that make it run. The UNO clone provides power is connected over I2C to the two DACs on the right side of the breadboard. Those provide the voltage out, which is fed over the brown and white twisted pair to the other side of the board, thru the diodes and to the wheelchair control box. The ribbon cable out the bottom goes to the wheelchair box and the wires coming out the top go to the joystick.
Since I got it all working and controlled by an RC transmitter, the next logical thing to do was tie down strap my snowboard onto the top of the chair and go for a rip around the neighbourhood.

I got more than one strange look but I had a lot of fun. Anyways thats all Ive got for now, next up is building a failsafe/joystick isolation board for a bit of safety and allowing me to seperate the added electronics from the original wheelchair electronics.

Realized after I published this post I said I would post all the useful links that I have found. Well here they are:
This one to a Stackexchange page asking pretty well what I want to know
This 2 page forum post that the Stackexchange post gets its info from
This interesting instructables post
This page from the manufacter of the joystick that shows you how to enter calibration mode
Product page for the DACs that I am using
And last but not least Adafruit's awesome tutorial with library for the DACs

One last thing. Here is a copy and paste of the code I have running right now on the arduino:

#include <Wire.h>
#include <Adafruit_MCP4725.h>

Adafruit_MCP4725 steeringout;
Adafruit_MCP4725 speedout;

int speedin;
int steeringin;

void setup(void)
  pinMode(5, INPUT);
  pinMode(6, INPUT);

void loop(void)
  steeringin = pulseIn(5, HIGH, 25000);
  speedin = pulseIn(6, HIGH, 25000);

  speedin = map(speedin,1035,1875,1310,3522);
  steeringin = map(steeringin,1035,1875,1310,3522);

  Serial.print("    ");
  speedout.setVoltage(speedin, false);
  steeringout.setVoltage(steeringin, false);


Thats it, thats all folks!

Thursday, 16 June 2016

Hacking a power wheelchair

Awhile back I purchased a Quickie Explore electric wheelchair with the intentions of turning it into a large outdoor robot platform to continue my explorations with GPS and mounting such things as a paintball marker to it. An electric wheelchair is the next logical progression in the series of outdoor robots that I have started and never ultimately finished. I keep getting near completion of at least a basic functioning base when something better comes along. Anyways, I think and hope that along with Raven (Which I have made some more progress on, or had anyways until the rear differential stripped out on the savage flux RC car base) this will be the final outdoor robot for a while. I have always dreamed of having an electric wheelchair with which to hack into an outdoor base because they are close to an ideal large outdoor base. Lots of battery life and payload capacity, like LOTS, very good motor controls built in, and very stable. I consider this and Raven to be parallel developments, as while they are both outdoor bots, they have quite different properties, raven being reletively small and very very quick and this one being much larger, slower and longer lasting. Perhaps in the future when I become a better programmer I will be able to make use of Raven's speed, but for now slow and stable are very good traits to have in an outdoor robot. Anyways, I had anticipated using the stock motor controller and joystick assembly, but taking the actual joystick out and emulating it with an arduino and some additional electronics. Before I opened it up, I thought that the joystick would use a couple of potentiometers as most joysticks do, and which I would be able to replace with a couple of Digital Potentiometers that sparkfun sells.
Well when I opened it up that was not the case at all. There was a large circuit board holding a bunch of electronics and an 8 wire ribbon cable attaching to a very scary looking joystick. After doing a bunch of research on the net, I found out that in fact it is a sealed unit that contains not 2 but 4 hall effect sensors which it uses as outputs. Each direction (X and Y) have two hall effect sensors that output similar but not identical signals as a sort of failsafe. The controller looks for the signals to be slightly different within a tollerance but mostly the same and if either signal strays too much from its partner, the controller detects this change and locks out. So in order to emulate the joystick's outputs I need true analogue voltage fed into the control board. I am not sure yet, time and some testing will tell, but I may be able to feed the same voltage into both of the pins that the board expects to see slightly varrying signals from the two hall effect sensors and recalibrate the control board to think that is normal. If I can then I can get away with only needing two analogue signals instead of the 4 the joystick currently feeds the board. Time shall tell. 

Enough of the boring postulating and onto the pictures of what I have got going right now!
Last night I was able to work some on the practical hacking of the joystick assembly. 
I cut the ribbon connector connnecting the joystick to the control board and soldered some 0.1" male pin headers to both the control board and joystick ends so that I can easily attach them to a breadboard and mess around with the connections and listen in with an osciliscope or multimeter to whats going on over the various connections. I was able to actually find a pinout (I think anyways) of the joystick online so I should be able to see whats going with relitive ease. Note hot glue as a very effective strain relief.
That done, I started working on the arduino/emulation electronics. Because a true analogue voltage and not a messy PWM quazi-analogue signal like the arduino's analogueOut function provides is needed to emulate the joystick, I chose the mcp4725 12 bit I2C DAC to provide that. I tried to find a 4 channel digital to analogue converter that I could use with the Arduino to no avail. The mcp4725 is an I2C device, but unfortunately it only comes in assignable to two I2C addresses. (Not entirely true, Adafruit makes a breakout board that has the addresses of 0x62 and 0x63 and sparkfun makes a breakout board that has addresses of 0x60 and 0x61 but I am cheap and impaitent. So I just got some clones of the sparkfun boards from some Chinese vendor on amazon.com, meaning that I will only end up with two possible assignable addresses). So if it proves that I do need to provide all 4 signals to the control board instead of just two, I will end up having to use two arduinos, each driving two mcp4725s to get all of the signals.
I downloaded Adafruit's mcp4725 library and uploaded the triangle wave demo sketch to the arduino, connected up a mcp4725 and.... Nothing. I had changed the I2C address to 0x60 in the example because the amazon clones of the breakout boards were clones of the sparkfun boards so I foolishly thought that they would have the same addresses as the sparkfun ones. A friend of mine with more paitence than me read a bit of the datasheet and rewrote the program to initialize 6 mcp4725 on all six (apparently the maker of the chip actually allows 6 addresses depending on the version, tho only 4 are commonly availible. Sparkfun's and Adafruit's) availible addresses and give a constant voltage instead of a triangle wave, and this time we had some action! Turns out the clones I have have the adafruit addresses of 0x62 and 0x63!
To change the address on the breakout boards, you have to cut two jumper wires on the underside of the board and change one solder blob on the topside. I did that and wired up the two boards to the arduino, wired the outputs to two multimeters (Thats where those bare wires sticking up go when everything is all connected up) and uploaded this sketch to the arduino:

#include <Wire.h>
#include <Adafruit_MCP4725.h>

Adafruit_MCP4725 dac62;
Adafruit_MCP4725 dac63;

void setup(void)

void loop(void)
      dac62.setVoltage(4095, false);
      dac63.setVoltage(1024, false);

Thats about as simple as it gets. The values are based on a formula you can find in the datasheet, but pretty well 4095 is 100% of the supply voltage and 1024 is about 25%. In this case it spat out 4.96v and 1.24v. Pretty freaking decent. Unfortunately I don't have any pictures or video of that part happening, but it all worked out perfectly. Thats as far as that part has gotten, it will probably stay in about that state on the breadboard until some more testing with the wheelchair is complete.

Speaking of wheelchair testing, before I got too carried away, I wanted to make sure all my solder connections were all good and some extra length of wire between the joystick and controller was going to be OK so I got everything all together and hooked up on the wheelchair and tried it all out.
The batteries are just sitting behind the battery bay because they are a huge pain to get in there and I wasn't planning on driving it around anyways.
Controller plugged into the actual motor control box at the front (You can't really see it that well in the pic. Normally it is covered by a nice protective metal cover as well.
And the hacked up joystick controller sitting on top connected to the joystick by a nice ribbon cable I had sitting around.
Annnnnnddddd heres the video of the quick test I did to make sure everything is still running tip top. 
Next steps are to drive it over to where I can set up my computer, osciliscope, a couple multimeters and all the arduino stuff and get sniffing on what I need to emulate and see if the joystick controller will take the signals from my mcp4725s like they are the joystick. Hopefully it all works!

Friday, 4 March 2016

The building of a flamethrower.

Over the past year or so, I have been ocasionally working on a homebuilt liquid fuel flamethrower, just on and off, whenever I had some spare time or money to buy parts. Today I finally finished it enough to do my first testing on the sucker. No flames yet, just some underwhelming water spraying, but enough to prove that its all coming together.

Thats the beastie there. Built from an aluminum frame backpack, an old SCBA tank, a paintball tank and accompanying remote line, and some misc. high pressure fittings and hose. I haven't got the propane torch on the wand in this picture cause I've yet to finish the final mount for it, but its together enough to finally allow me to do a proper pressure test on the whole thing. 

Safety has got to come first when you are building something like this. 800PSI, Gasoline, mistakes and sloppy work do not mix very well.  So I am taking it slowly, making sure things are done right. Anyways, I got it done enough for a pressure test. I filled the fuel tank with water, screwed on the valve assembly at the top, laid it down on my concrete front steps and ran the remote line to the air tank inside:

When I actually run gasoline or diesel in it I will be using a 20Oz CO2 paintball tank as propellant to ensure an inert environment in the fuel tank and all the lines right up to the nozzle. Both fuels will not burn in a liquid form, only the vapours burn, but the CO2 ensures that there is absolutely positively no chance of a flashback into the tank. Safety first. But CO2 is expensive and I am just using water for the moment, so I am safe to use my 48cu.in. paintball HPA tank instead. The scuba tank I used to fill my HPA tank didn't have very much pressure in it, so I only managed to squeeze in about 1000 of a possible 3000PSI:

Doesn't really matter for the pressure test because it has a regulator that takes it down to 800PSI anyways, I just did not have the volume to keep the tank at that much pressure for very long. 

With that all set up, I ask that you please direct your attention to the video below. Exceedingly poorly filmed iPhone first person flamethrower pressure testing:

As you can see from that video, (sorry for the shakeyness and the general poor filming quality, I'm a tinkerer, not a film student) my remote line disconnect had not seated all of the way and was leaking a bit. I fixed that up and tried again:

Mostly leak free. Most importantly, the fitting that I tapped and O-Ring'd into the bottom of the tank held beautifully,  but there were two of the NPT connections I had not tightened up enough and had very small leaks. This would be exactly why you always test with water first.
The JIC union right off of the bottom of the tank sealed up nicely, it was just the two joints at the coupler. I have since taken them apart, re-doped them and re-tightened them to a tighter fit. At the time of writing I have not re pressured them back up to see if they hold now. 

Couple of things to note about the video, first, again sorry for the terrible quality, trying to film and do stuff at the same time is rather difficult with no proper equipment. And second note the totally underwhelming spray coming out of the gun. This is do to a couple of things. Most notably that the propellant tank was as I mentioned only filled to 1000PSI. So after the very first shot, which I didn't even get in the camera lens, the pressure in the whole system dropped to probably drastically less than 500PSI. When a CO2 or properly filled HPA tank is used, it should keep the system at a fairly constant 800PSI throughout the entire full to empty cycle of the fuel tank. And second, I did not have any sort of restriction at the tip of the wand, it was shooting at as full of a volume as a 1/4" pipe could muster. If I were to reduce the size of the opening from which it sprays, it would shoot less volume but much farther. 

Those things said, if you take a look at this video from this guy: (absolutely no relation or endorsement or anything besides me finding his video on youtube and thinking it was reletively neat) you will see that his stock flamethrower shoots water about the same distance, and flames much, much further. So even with it as it is, it should shoot some decent flame. 

Anyways, thats it for now, be safe out there and have fun!

Sunday, 24 May 2015

I'm still alive :)

Yeah, so I haven't posted anything here since December of last year, and seeing as its nearing the end of May, I just thought on the off chance that anyone actually reads my blog, you don't have to put it on your list of totally abandoned blogs. I'm still alive and still building robots and things that go boom, however at a much much slower pace than I was before. 2015 has been a bit of a crazy year for me, I turned 19, the place that I was renting sold and the new owner decided they didn't want to rent to me anymore, so I bought small house, and had to move into it, which means that even tho I moved in more than a month ago, most of my stuff and all of my robot making things are still packed away in boxes in a shed. Plus the fact that I work full time, and help out at my church, well, it all sucks your time away quite quickly, and suddenly you don't have time to do much but try to survive :) Anyways, Im still here, and I will get back to posting more regularly when I get a tiny bit more time in my life.


Thursday, 11 December 2014

Yeah I can't stick to one project.

I have project commitment issues. But hey, whatever, they all need to get done someday! Anyway, with my Camaro sitting outside just waiting and calling to me, I had to caniblize it. Brought it inside and started taking stuff off. I also brought PK, or what was left of him after moving, upstairs and ripped the parts off him too. Ended up with this collection:
The motors are a little different, or rather the gearboxes are. The new ones have different mounting flanges, and the pass thru shaft hole size is slightly smaller in the new ones. But the gearing looks identical and the motors themselves also do. And big bonus, the crazy wavy hexagon that power wheels toys use to transfer power is identical on both, so I can use all four wheels from the Camaro. Also, the snazzy mags just pop out leaving me with some plainer, but honestly more my style wheels. As snazzy as those are, I think I am going to be leaving them behind when I go forward. Ill keep them around and if I ever need to enter a paintball packing autonomus car into a car show or something, I can add them for the extra bling. In addition to being slightly larger diamiter, the other car's axle was also longer than this one. but that is no problem, I shall just cut it down and tap some nice threads on the end like the original car had. Here is a super quick mock up I did to get a generall idea of size:
You can clearly see the legnth difference between the two in this pic tho the angle of the camera does cancel some of it out.

But thats not everything to do with PK yet! I never made a post about this but a few months back I visited princess auto in Kelowna and found these beauties really cheap in the surplus section:
The are HUGE open contact DPDT relays. As I said, got them very cheap, but unfortunately they have a 24v coil. I anticipated being able to drive them at 12v no problem, but I just tried them on a 12v battery and no dice. No problem, I will just make a voltage doubler. It will make things slightly more complicated but not overmuch.


Tuesday, 9 December 2014

Goodies :)

Over the weekend (yes I am a little late, but life is busy) of the sixth and seventh, I was down in Spokane and I went to the wonderful sketchy terrible store that I love to find great deals at so much. Jeez I love that store. They actually took the piles of junk that are my favourite part out of the normal stores and moved them to one store exclusively full of total junk, and its like paradise in there. Anyway, so I bought a couple things, from least to most impressive here they are:

Two more night vision security cameras, cause I just can't get enough of those :) 
No particular plans for these two little suckers, just put them in stock for next time I need a security camera. Perhaps if I ever find the need I will set them up with a computer and a video capture card and a huge hard drive for some monitoring of my place. 

Two of these LED lightstrips. They are 5 meters long with 27 segments of 6 LEDs each.
They came with the little box you can see in the top right hand corner, its designed to recieve a signal from an IR remote control to control the pattern, but neither of them came with the remote. Anyway, I googled around for a while and found that I could simply control them with my arduino using Adafruit's awesome NeoPixel library.
There is my ugly hacked together setup to see if it actually worked. Which it did :) here is a video of both of them running, the one in the spool is the stock demo mode that it defualts to when its on, and the unrolled one is the one being run by the arduino.
The only thing to note is that on the spooled one, there appears to be a connection break about half way thru, but if you flex it a certain way, it still works as is evident in the video. Because of the way you can chain these things its no big deal, Ill just cut that one segment out and resolder them back together, or use them as smaller strips. I plan on adding these to The Window for a nice light show as well as orientation, as suggested by Duane Degn on The Window's Letsmakerobots page.

And lastly I picked myself up a Chevy Camaro...

 Ok not really:
 A couple of posts back I mentioned I have trouble sticking with one project, and its true. I really do. Anyway, I picked this bad boy up to help totally revamp Project Killzone. Pretty much ever since I picked up the two motors that are in PK now I have wished to have two more so that I could make a nice sturdy 4 wheel drive chassis instead of the 2 wheel drive one I have now. Anyway, the oppertuinity came along finally to get two more at a resonable price and also, I think (think, have not tested this yet) I can use all four wheels that came with the car, cause they don't appear to need the adapter couplings that the other wheels needed.

As you can see, it uses identical wheels on the front and back, excellent for me :) and if the motors are the same then I should be able to just slip the new wheels onto the old motors. If that works, PK will end up looking signifigantly different.

The best part of this all? All of the above was purchased for a grand total of 25 US dollars. Not too freaking shabby considering that is the price for ONE meter of LED strip from sparkfun.com and if you want 5 meters? $120. Granted, they have more LEDs and each individual one is addresable, not every 6, but still. Quite the deal I'd say.

Well thats really all for now, once I get something done on my projects, ill post the proof :) Happy Hacking!

Monday, 8 December 2014

A sorely overdue update on The Window

So after I posted about my future plans of mounting a paintball gun to The Window, and making a refrence to the pan/tilt turret I had mounted on it, I realized that I never actually got around to posting that update. All of this was done way back near April sometime, but I never did anything with the pictures. Anyway, to the good stuff.

Before I get into the nitty gritties, here are a few shots of the whole thing from different angles:
As you can see, I added some landing gear to get it up off the ground in order to mount the gimbal below. The landing gear is made from some more 1/2" PVC and 4 1/2" to 3/4" tees that had half of the the T part cut away so they could be screwed to the edges. It was straightforward with two things to note, the dimond shape is due to sloppy work on my part not getting the landing gear tees all mounted at the same angle and thus needing different legnths of pipe to make it sit on all four legs, and the string running around the landing gear is due to the frame flexing a little without the support. When there was no string running around the perimiter, due to the angle, the legs would flex out, causing the 4 center arms to flex and be under stress when it was sitting on the ground and potentially breaking them on a hard landing. My solution was to run a string around all of the legs and so keep them from being able to bend outwards. The string itself is one strand from a DCCB 1800 YG Dacron rope used to Aero tow gliders. There was some short ends left over from making glider tow ropes and I snagged some, one strand from the rope is more than strong enough and has absolutely no stretch at all making it perfect for this.

Using my usual ultra high quality manufacturing methods of zip ties, hot glue, and this time a little aluminum, I cobbled this sucker together:
I originally thought that my ATC mini would output video as it recorded, but it turned out that the video out jack was just to be used for watching the footage afterwards, useless for what I wanted. So after struggling around for a little while and burning out at least one board-level camera I ended up with the ugly-as-all-get-out (whats new eh? It fits with the rest of the build) camera/solder/hot glue job you see there. I think the camera came out of one of those "Spy Gear" kid's toy remote controlled cars with a camera mounted on it that my friend disassembled. I soldered a piece of coax from an old RCA cable to the video out and ground and just used a single strand of hook up wire twisted around the outside for power. It is mounted to a piece of aluminum which also mounts the ATC mini and is connected to the tilt servo, bent so that the two cameras are both looking in the same direction. As for the servos, as you can see they are zip tied to each other and attached to a tee with half cut off of it and the center high point filed away for mounting on the octocopter. The tee is simply hose clamped to the frame for easy removal. In these pictures you can also see the video antenna which is the large PCB with a copper square on it. This brings me to this picture:
You can see in the upper middle of the picture a small proto circuit board, and mounted on it is the module from a 2.4GHz video sender. I purchased the video sender kit a long time ago and used it in various robots and such, and a little while ago I removed the module from it. Basically inside of video senders are small little boxes with pins sticking out that are the actual transmitter and are much much smaller than the whole unit. Mine was about an inch squared and like a quarter of an inch thick. The only snag is that it required a regulated 3.3v supply which I did not have on hand. So I ordered a tiny little module that had everything included and simply in and out leads. I soldered everything onto the proto board and added a few jacks for connections. That explains why the antenna is that plate directonal antenna, it was the stock one from the video sender. You can also see in the picture the RX for the pan/tilt gimbal, just a fairly standard 3 channel 27Mhz hobby set of which this is the TX:
That is about all there is to say about the octocopter itself, but I have one other acessory that I would like to talk about before I go. The idea was for me to fly the octo while someone else has the gimbal controller and a screen showing the video. Well in the intrest of portibility, I decided to make a DIY headset for the cameraperson:
Go ahead and laugh, I admit it looks totally stupid, but hey it works :) its reasonably straightforward, viewfinder hacked out of one of those huge old camcorders, hooked up to a circuit board to regulate the voltage to it and have some nice video connectors, 2 cell LIPO battery and the video reciever all strapped to a baseball cap. Yeah it looks totally stupid, but it was fun to build and it does indeed work. The trickiest part of the whole build was getting the viewfinder positioned correctly in front of the person's eye. I wanted a handsfree solution and this was the best I could come up with with what I had. I think that actually a cowboy hat would be ideal but this is all I had. I played around for a long time trying to get something that would mount on the cap, be reasonably comfortable, and have the viewfinder positioned reasonably well, and that is what ended up working best. Its just a piece of scrap aluminum screwed to the brim in such a way that the bottom is about in line with the top of ones eye, so the viewfinder is in line. There isn't much else to say about that I think.

All ready to fly:
Thats the last picture I promise :) Thats what it looked like with everything needed for a filming outing. The only problem was that the 2.4Ghz signal from my octocopter TX caused huge interference in the video signal back to the base station, making it almost impossible to see what you were filming. But the proof of concept worked decently, it just needed better equiptment. Anyway since then I have disasembled the video part of this thing, and I am working on my paintball gun mount as mentioned in the last window post.

So thats all for tonight, Happy Hacking!