First off, if you choose to go all the way and make this use the flyback circuit like I did, you need to understand you are dealing with VERY high voltage, and even though it is technicaly static, under the right circumstances, even static can kill!, So please have at least a basic understanding of working with high voltage, or get the assitance of someone that does! And please, dont electrify any pets, neighbors, siblings, parents, bosses, ect,ect, no matter how tempting it might be =) And seriously, DON'T touch ever touch the electrode, the aluminum plate oranything inside the monitor or TV that you dont recognize!!
Step 1: Getting your parts!
However if you do need to scavenge for parts, places like, Good will, SOS, salvation army, are great places to look, usually you can get printers, and scanners for 3 or 4 dollars U.S., Also, hit up relatives!
You will need 1 flat bed scanner.
1 old printer
1 old remote control car, Has to be full function.
1 old wall transformer with a 5 volt DC output, and you will need 2 monopolar capacitors, I used polyester film capacitors, radioshack sells them, for only 2 or 3 dollors. (they MUST be monopolar)
A few small pieces of metal and plexi glass.
2 Long springs, mine came from 2 old flexible automotice magnetic retriving tools.
2 servos, I used 2 futaba brand, model S3003, 44.4/56.9 oz, torque, I don't wouldent using anything smaller. Got mine from hobby town, 10.99 u.s.
A piece of plywood, or press board, a 2 foot square should be fine, I already had some, but it would be pretty cheap at menards, they sell it in 2 foot square's for about 3 dollars U.S.
You will need alot of assorted screwdrivers, including some star heads, and possibly some safety screw tips, an exacto knife(s), a soldering iron, and some heat shrink tubing, red and black wire, stranded or solid.
You will need a hot glue gun, and LOTS of glue sticks, (again, this isnt meant to be as presice as a CNC machine)
Step 2: Tearing down the scanner.
This scanner had no screws, it just popped apart with some tabs on the back side of it.
You can take out all of the electronics inside, we wont need them, but save them, you can use them in other projects. Be sure to remove the stepper moter as well, and hold onto it, we wont be using it here, but its still good to have some lying around, never know when you might need one.
Step 3: The scanner carrage
ok, getting the scanner carrage ready, first thing, take the belt off of the pullys, this is very simple, one side has the motor, the other a pully on a spring loaded arm, so just grab the belt on the side with the motor, and pull, the belt will slide right off.
Next gotta remove the steel guide, the steel guide comes out very easy there will be a pin on one side, pull the pin, and the steel guide slides right out.
Next, you need to start stripping the electronics off of the scanner carrage, again, I cant get into great detail here, i have taken apart, 4 or 5 myself, and they have all come apart a bit diffrently, but, generaly very easy to take apart.
Here are some pictures of the carrage being taken apart.
Once you have striped all the parts off of the scanner carrage, put the scanner back together the same way it came apart, so that it can be moved left to right, by hand, move it once, make sure it is working correctly.
Step 4: Modding the carrage into something usefull!
As you can see here, I removed the stepper motor, but I left the gear box intact, the belt has to have something to ride on, so as you can see here, I have a empty scanner bed, and I have everything back together, so the scanner carrage moves along the bed like it was intended to do.
Time to start adding the parts to the scanner carrage.
As you can see here, you will need to cut some small wooden blocks to fill in the empty space in the bottom of the carrage, glue these down with your glue gun.
Next, cut a piece of plywood large enough to fill in all of the empty space left over from the top of your wooden spacers, I was able to do this on mine, very easily, you may not need to do these steps, it just depends on the design of your scanner, as you can see, I had to add some spacers to mine, befor adding the top layer.
When you are done, it should look something like my last picture.
Step 5: Makeing your sliding assembly.
First things first, you will need to cut a piece of plywood long enough to hold everything, look at my completed picture, to get a good idea of what this is going to be holding, also take into account the overall length of your drive belt when you decide on how long of a trolley to make. You need to measure the overall lenght of your drive belt, and take that into accout on where your wooden blocks will be mounted. you also will need to take into account the diameter of your drive wheel and your pully.
First thing you need, is a piece of plywod long enough to hold, 2 3/4 inch wide pieces of wood, you can use plywood here, but i would recommend using any type of 1 by, material, as it is better suited to what we will be doing with it, you can see from my second picture, the general idea of what we are making starting to shape up.
You will need enough room between the3/4 inch wood block, and the end of your plywood for 1 servo to be placed. I left 3/4 of an inch, this was more than enough room.
Ok, you need to mesure up, how much motion you need to make your trolley be able to move the full width of the scanner bed, When you know that, you can figure up how much extra wood you will need, so if you want 11 inches of movement, you will need a space of 11 inches (inside dimension) between your outside wooden blocks, so 11 inches, then add 3/4's of an inch twice, so far your up to 12 1/2 inches (this is only a guide, yours will vary, please mesure befor you start) then you need at least 3/4 of an inch on one side for your servo to be placed, so that means you need a total if 13 and 1/4 inches of plywood, as your base.
So after you have mesured your needs, the best way to start is to draw a line in the center of your plywood, then mesure out to the left and the right side, so, if you need 11 inches of travel for your trolley, you will mesure 5 and 1/2 inches to the right side, and 5 and 1/2 inches to the left side, of your center line, put a mark at 5 and 1/2 inches, on both sides, this is were the INSIDE face of your wooden block will go, this is important, if you put your blocks on the wrong side of the line, you will end up with 9 and 1/2 inches of travel, instead of 11.
Ok so, now that we have our lines, its time to cut our blocks, I mesured mine at 3 inches, you dont want them to small or you will not have enough wood to drill the holes for your guide rod.
Attach the blocks on the outsides of your lines, with a SMALL amount of hot glue, then turn the plywood over, and using a drill with a 3/32nd inch drill bit (Or the closest to that size that you have) Drill 2 holes, thru the plywood and into the wooden blocks, do this on both sides, then holding onto the block firmly, use your drill, or a screwdriver, and put a drywall screw into each hole, only turn it till it is snug, so you dont strip the hole.
Next you will need to make a bottom guide, for your trolley to rest against, I used a piece metal from inside the printer I took apart, you can see it installed on the 3rd picture, I used a piece of 3/4 inch thick, 2 inch wide, 2 3/4 inch tall, wood, for the body of my trolley, so i set my guide bar 1/2 inch back, from the front lip of my plywood that way i have 1/4 inch of the trolley body hanging out past the edge of the plywood, Then using the plastic housing of a crayola marker, cut off 2 small shims, to put under the top lip of the guide bar, then put 1 drywall screw into a hole on each end, mine had pre-drilled holes in the right places already, you can also use a piece of wood for the guide if you want to.
Step 6: Finishing the trolley assembly.
Now to finish it up, first we need to mesure and drill 2 holes, these will hold the guilde bar on the top in place, I mesured and drilled my holes, so that the far side of the rod, that is, the front edge, lines up exactly, with the front edge of the bottom guide, The rod I used turned out to be 1/4 of an inch thick, 1 half of 1/4 is 1/8th inches, so to make them line up, mesure in from the front of your blocks, 3/4 of an inch, then add 1/8, for a total of 7/8ths of an inch, the highth is up to you, and what size trolley you plan to make, just make sure you have at least 1/4 inch of wood between the top of the guide bar, and the top of the blocks, and make sure the holes line up EXACTLY, this is the most important part of the build, if you have access to a drill press, I highly recommend you remove your blocks, clamp them in a drill press, and drill them both at once, just make sure they are lined up exactly even all the way around.
Now, you will need to cut your metal guide rod, you only need it long enough so that it goes into your holes and goes all the way to the outside of both wooden blocks, you can see from my picture, mine is about a half inch longer, on both sides, but it doesnt have to be, i put some hotglue around both ends of mine.
Now you need to make your trolley, like I said I used a chunk of the same wood I made my end blocks from, yours might vary from mine, depending on your platform, and scanner, but mine was 3/4 thick, 2 inches wide, and 2 and 3/4 inches tall, here as well, I used the housing from a crayola marker, as my guide, it fit over my guide rod, a bit more loosley than i would have liked, but it turned out not to be a problem. I sat my trolley block, up on the platform against the bottom guide and the top guide, and then put a mark on the back of my trolley block were the guide tube would go (i lifted mine 1/4 inch off the bottom plywood, so that it wasnt siiting right on the plywood) then marked the back were I wanted my guide tube to be placed. I secured mine, with LOTS of hotglue lol, it holds just fine, havent had a problem with it yet.
Now, put one end of the guide rod into one end block, then place the trolley block with the guide tube in place, over the guide rod, then slide the guide rod into the hole in the other block.
Step 7: All glued together!
Now that your trolley is finished, its time to attach it to the carrage assembly. This is pretty simple, just take your finished assembly, and set it on top of your carrage, and make sure it is lined up in the middle, and glue it in place. Pretty simple.
Apparently, I neglected to take a single picture of the trolley assembly completed, without the servo attached lol, so ignore the servo for this segment =)
anyways, it should look like this when mounted, again sorry for the bad picture, apparently out of 600 of them, I forgot to take a few lol.
Step 8: Servo hacking.
Ok, For those of you that already know how to make a servo run continuously, ignore this step, for those that dont, here is a short tutorial.
Essentually, a servo is just a motor in a gear box, with a circuit that runs off of a signal from a servo controler, and limits the servo's motion, to mod our servo's were just gonna bypass the driver circuit, and go directly to the motor.
First thing you will need is some small screwdrivers, and a soldering iron.
First thing we need to do is remove the back from the servo case, there will be 4 small screws in the back, probably phillips head, just take them out.
You can see 3 wires attached to the circuit board inside the servo case.
using your soldering iron, heat up the connections and pull the 3 wires off of the board. Next, on the top of the circuit board, you will see a variable resistor, it will be attached with 3 leads, simply cut it off of the board, and put it aside, you might find a use for it later. (please look at the pictures if you have any questions) Next, you will need to solder the red and black wires onto the motor, it really doesnt matter what lead u solder to what side, as long as u make both of the servos the same.
All done with the soldering. Now onto the hardware modding part.
now that were done with the wires, we need to take the top off of the servo case, to get to the gears.
Remove the servo head, and the top of the case will lift off, were after the large gear inside, it will look something like the gear highlighted in the picture. There is a little bit of cutting to do here, you can see the small rectangle with holes in it, highlighted in the picture below, we need to remove it, I used a dremel tool, seemed like the best way to do it.
Step 9: Mounting the Wheels onto the servos.
All servo's come with a variety of heads we will be using the round head.
Here is were the remote control car comes in, the first part anyways, we need the wheels, so start pulling them off, we will need 2 of them.
Ok, were going to be mounting the round servo head, to one of the wheels from the remote control car. i got lucky, my wheels were the same size as my servo head, as you can see in the pictures.
Ok, if you happen to get unlucky, and your wheels are smaller than your servo head, you will have to mark out the middle of the servo head, and then center your wheel in the middle, and draw a line around it, then cut it out, you dont HAVE to make the cut round, you can just cut it into a square if you want to, just as long as its smaller than your wheel.
Then mark and screw, make sure it is in the center, if its not, just take it off, and turn it a bit, and try again.
Below, I have a picture of the completed servo.
Step 10: Mounting the first servo.
Ok, here we will need some hot glue, and you will want to glue the servo to the side of the scanner bed,in the middle, I had to use a small piece of plastic as a shim, but anything will do, wood, cardboard, doesnt really matter, next, you will ned to drill 2 small holes very close to the ends of the servos, and put a zip tie thru it, that way your servo can't pop off.
Step 11: Mounting the second servo.
I high lighted the pictures below, showing were the servo should go, one thing to keep in mind, you want the front of the wheel on the servo, to be lined up with the guide rails on your trolley. On the other end of your trolley, you will need another pully, I took mine, and my belt out of an old printer, you want the pully to be mounted were the front edge is lined up with your guide rails, also take into account, the over al length of your belt, if you did step 5 correctly, you should not have any problems here. So once you have measured out and found the right place for your pully, go ahead and get it mounted, i drilled one hole in my plywood, and put the shaft with my pully on it, into the hole, and just blobbed some hot glue under the pully, so it couldent fall down to the plywood base on the trolley.
Step 12: The wireing.
Alright, here were gonna steal a few more parts from the remote control car, this time we want the heart lol, we need the circuit board out of it, make sure when you take it out, mark the + and - on the wires when you cut them off of the battery box, make sure you mark them, because they might not be red and black, mine were, but i have found some were they were both blue, and another were they were gold and brown lol.
When you remove the circuit board from the car, be very careful not to break any of the wires off of the board. Make sure you have marked your positive and negative wires from the battery case, and make sure you when you remove them, to take the switch with it you will need it, now cut the wires off as close to the battery box and motors as you can, we want plenty of wire to work with.
the very first thing that I did after removing mine, was mount it to the side of the scanner, my reasoning was to have a nice sturdy base to work with. After you mount your circuit board, its time to start wireing, the first thing we need to do here, is hook up a new power source to the board, its very important you dont use to much voltage, and end up burning out the board, use no more than 5 volts, otherwise you might end up damaging the intergrated circuit on the circuit board, I re-used an old cell phone wall charger, it puts out 5 volts DC at 0.75 milliamp's, if you have a transformer with to low of an amp rating, your servos wont move very good, i wouldent use anything less than 0.50 milliamps, I used a 0.35 milliamp transformer the first time, and my servos wouldent move lol.
Cut the end off of the wire on the transformer, just make sure its unplugged lol, strip the ends of the wires, then take a multi meter and test the leads, just touch either lead to either wire, if you have the leads backwards, the screen on the meter will show a - (minus) sign, this is how you can tell which wire is positive and which is negative, after you find this out, make sure you mark them. Now we need to solder the power leads from the board to the transformer leads, so if you marked your wires in the beggining, you just need to solder positive to positive and negative to negative, make sure befor you solder your leads together, you put some heat shrink tubing over the leads, about an inch from the ends, any closer and the heat from the iron, will shrink the tubing in the wrong place, after the leads are soldered in place, slide the tubing over the connections, and heat it with a lighter, careful not to leave it on to long, if you do, it can catch fire. While you are doing this, be careful not to break the wires off the switch.
Now onto the servo wires.
Ok here we will need our capacitors, they MUST be monopolar capacitors. The reason that you have to use monopolar capacitors is because the polarity of the wires feeding our servos will be switching polarity. In essence, if you hook up a polarized cap backwards, it will over heat and the fluid inside will start to boil, and will eventually start to ooze out, and well, it generally just makes a big mess lol, but with monopolar cap's we dont have this problem.
The reason we need the capacitors is because the servos are going to be starting under a load, and the capacitors will help take some of the strain off of the electronics, it wont pull as much spike voltage thru your circuit board, and the motor in the servo itself will start easier, in general, it will extend the life of the electronics. the capacitors are non polarized so it doesnt matter what lead of the servo is soldered to what side of the capacitor. the easiest way to do this, is to bend the capacitor leads towards the front side of the capacitor, and then strip about 1 inch of insulation off of the wires, then, twist the exposed wires together, now take your soldring iron, and heat up the exposed wires and apply some solder to them, make sure to get good coverage over the whole exposed wire, and be carefull not to leave any blobs of solder behind, if you do, just place the iron under them, and after the solder turns back to liquid, pull the iron down the length of the wire quickly, and off of the end,the solder will come with it, now cut some heat shrink tubing, about 1 inch long, and put one on each servo lead, now take the capacitor and set it as close to the insulation on the servo leads as possible, with the bent leads pointing out towards the bare wire, you can wrap the capacitor leads around the wire, it will make it easier to solder them, or just solder them however you normally would. Do this for both servos.
Step 13: More wireing
Now we need to strip the ends of both sets of wires that ran to the remote control car motors, and solder the ends of them. Now get some alligator leads, and clip one to each motor lead, and then clip each end to one of the servo leads, Then turn your power on, and take the remote from the car, and push each joystick, until the servo moves, You will want the joystick for the left and right turns to be connected to the servo that moves the scanner trolley left and right, so after you figure out which set of leads works the left and right turns, go ahead and mark them, You can go ahead and connect them the servo that moves the scanner trolley left and right.
The other set of motor leads obviously moves the car forwards and backwards, so they will be connected to the servo that is mounted ON the scanner trolley.
Next we will need to put on the belt, and connect it to the sliding assembly on the trolley. that way we can test everything out, this is pretty easy, just slip the belt over the pully, and the servo head, put a mark on the back of our sliding block, were he belt rides at, then we need a small piece of metal, or wood, and some screws, we need to attach the belt to the sliding block, so go ahead and screw a piece of wood or metal over the back of the belt, into the sliding block, and screw it down tight, be carefull not to strip out the screw holes. Also i had to put a cap on top of my servo head, because the belt kept slipping off of the top, i used some plexiglass, but a small piece of wood or even cardboard would work just as well.
Now its time to connect the wireing to the servo mounted on our sliding assembly, since this servo will be moving left to right, we will have some problems with our power wires dragging or getting hung up in the trolley assembly if we dont do something about keeping them up, so i took an old spring, drilled a hole int he base of the scanner and threaded the spring thru it, then glued it in place with some hot glue, just becareful to leave the bottom of the spring open, so you can run your wires thru it (you can see in my photo only one of my wires fit inside, but later i found some duel strand wire that fit thru the spring, thats ideal, but if you have to run one inside and one outside, thats fine too) get your wires ran out thu the spring and then connect them to the servo wires, all done!
Go ahead and turn it on and do some tests, the left and right car function, should move the scanner trolley left and right, and the forward and reverse functions should move the sliding assembly up and down.
Step 14: Finishing up.
Alright now we need a writing surface, I just took a piece of aluminum, and cut it to fit inside the rails on the scanner bed, and glued it down. then I glued a marker to the sliding assembly, on the trolley, Now you are ready to draw some pictures!
Here are some random drawings I made, nothing fancy just showing what it looks like.
Now, if you choose to stop here your finished, if you decide to go ahead and add the flyback circuit, to draw on thermal paper, please go on to the last step.
Step 15: Flyback.
I used a piece of 8 gauge wire, mine was a piece of ground wire, so it had no insulation, hence the heat shrink tubing you see in the picture, but i'd use wire that still has insulation on it, grind one end into a nice fine point, then, I took a piece of wood, and test drilled holes with diffrent bits, to make sure I got a nice tight hole drilled to put the electrode into, I added some pictures of all of this below. I used about 2 feet of wire with the thickest insulation I could find, and soldered one end of it to the electrode, the other end went thru the spring and down to the scanner bed, I had about 6 inches left over at the scanner bed, I stripped it a 1/2 inch and soldered it.
Then in one corner of the aluminum plate, I drilled a small hole, I took about 2 feet of black wire and stripped 2 inches off the end of the wire, I put it thru the hole I drilled in the aluminum, and wrapped it about 3 times, then hotglue'd it to the aluminum plate. and that was that.
Now im going to turn you over to another instructable for the info on the flyback, Since as I said, never took any pictures of my modified TV =(
NK5 is the author of the instructable about hacking a computer monitor, I take NO credit for anything inside of his instructable, and have read it myself, its very good, and i wold like to thank him/her for the posting!