Finally...

[kibble]

Well, I do believe I'm finally gonna start making my kart! I went to a local junk yard today with a friend to see what parts I could take out of a regular car that might be usable in a kart. I ended up taking the differential out of an older Nissan Sentra, which wasn't difficult to do as someone had already taken the engine and left the transmission just laying there. I'm hoping it's not too overkill for something like this, but I do want to use a diff and didn't really feel like spending $150 for one. For about $100 I ended up getting the diff, cv joints, a master cylinder, and a windshield washer fluid reservoir (to replace the broken one in my gf's car). I will take some pics of what I'm planning on using as soon as I can find the battery charger for the digital camera... figures, it's not available when I need it.

[kibble]

I had to resort to using my phone to take pics of my stuff. There's a pic of the engine I plan on using and there's a pic of the diff with the cv joints. I plan on modifying the cv joints somehow though.

[robertdjung]

sounds good. Looks like a honda, or honda knockoff engine. I use one of those that's a 6.5, great engine.

[kibble]

It's actually a Subaru Robin engine, I didn't show the back where the recoil is but, it's supposed to be a 9hp engine. I ran it today for the first time since I got it and it sounds really clean. It idles really nice too, so nice that it hardly sounds like it's running. I was actually waiting for it to stall but it didn't. It was either this engine or the 11hp. The 11 is really noisy though.

[kibble]

So I was thinking of how to operate the throttle on the engine and I decided I don't really want to use a wire. What I will try to do instead is operate the throttle with an R/C servo. I would have to make some sort of mount for it but that shouldn't be too big of a problem. I will make a circuit board that has a potentiometer on it that attaches to the gas pedal. I was looking online yesterday for a schematic that would control a servo and I found one that looks simple and decent, I just have to build it now. Will post pics and maybe a video if it works like I want it to.

[robertdjung]

hmm. Just make sure the "default" position is off. I'd hate to see your RC crap out and you drive off a cliff.

[kibble]

Well the system for it is not going to be radio controlled, the servo is the type that's used in an R/C system but it's going to be controlled through some small wires. I was actually planning on also setting up a device that would detect if the servo stops responding to the input and would automatically shut off the engine. Yes, it's more complicated than just using a single wire to control the throttle but hey, that's what I do. I believe that if it works, fix it! You gotta be creative after all. I went and bought some of the chips I will need for the circuit board today. I will probably start making the board later tonight. Of course I'm gonna put the system through some thorough testing before I put it in use to make sure everything works as planned, safety is #1. I want to be able to enjoy what I made instead of riding once and ending up in the hospital! LOL :D

[mikeandike]

can you send me the schematic for that? I'd like to take a look at it. For your circuit boards wut method do you use?

[kibble]

Sure It's:

http://hades.mech.northwestern.edu/wiki/index.php/555_Servo_Circuit

I etch my own boards. I just use blank copper boards, permanent markers and ferric chloride. I used to make boards out of those experimenter ones they sell at Radioshack but I eventually moved to making my own. I eventually want to get into photo etching.

[ryf]

I think this is an awesome idea.... my only thought would be to test it for a long time on stands (tires off ground) and make sure there isn't a problem that isn't instantly obvious. when you get electronics, things don't always do what you expect. so be careful and let us know what happens.

[kibble]

Oh yeah, I know. I've had things go "POP" many times and even catch on fire! If you look at the included pic, you can see an aluminum heatsink in the middle with a really dark spot on the top, right hand side. I was building a power supply and that was a MOSFET that couldn't take the stress I was putting it through and it literally caught on fire. Too bad I didn't have the camera when it was actually burning cause it was pretty cool! :p

[mikeandike]

LOL. I was making a voltage regulator (really simple no mosfets or coils, 1 chip) and i had a big capacitor on it 4700uF 50v. It wouldnt decharge so i put it on a piece of metal and there was a big spark and it made a small dent in the plate. I also reversed the polarity on an op amp and it started smoking.

Anayways, I used to etch boards with sharpie marker but i wanted to try something new so i got all the stuff for a photo resist method (transparency film (you can get it @ an office place cheaper), florescent light (already had one) , a piece of glass (from a picture frame) and some developper (electronics store). All you do is draw something up on the computer (free cad things that suck) and print it. I believe it works better with a laser printer but my inkjet has a transparency film setting that works ok and you can reuse the paper again :P

[kibble]

Ah yes, making sparks with caps is always fun. I bought two 100V, 14,000mfd caps on ebay. Charged and touched to metal makes nice loud pops.

I have a laser printer that I could use to make the transparencies but I don't have the transparencies themselves. I remember I tried regular transparencies not made for laser printers once... that was fun, trying to get it out of the printer that is. I'll get to making photo boards eventually, in the mean time I use some etch resist dry transfers that I bought at radioshack to make all the pads for the components and then I draw in the traces with different thickness sharpies. I didn't get to work on my servo controller board yesterday but I did draw up the traces on a piece of paper so that I know how it's gonna be wired.

[Crabapple]

sounds neat!

[kibble]

Finally got around to finishing up the servo controller board. It works great! Now all I have to do is find a way to attach it to the engine and test that out.

[ed1380]

I'm pretty much uber stupid in electronics. is there anyway you can get a botom shot of the pcb?

I found this (http://www.seattlerobotics.org/encoder/200210/servoex/schematic.gif). can the jumper in the top left and bottom right be removed and just closed? what are they for anyway?

[kibble]

Here you go.

On that schematic, it appears that the two jumpers you're talking about are just test points so that you can test out the board with an oscilloscope. They aren't necessary and don't do anything other than that. If you were to build that board you can just ignore them as if they weren't there but you wouldn't want to jump the two points.

I made a mount for the servo to attach to the engine and I'll take pics of it once I've mounted it on the engine.

[kibble]

This is what the servo looks like attached to the mount and what the whole thing looks like assembled. The wire attaching the servo to the throttle is not the one that's gonna be used. It's only there for representation of how the two are gonna be attached together.

[my_mini_bike]

lol, on my go kart i just used an old bonnet cable connected to the pedal. but yours works too :p

[kibble]

I finished the servo-throttle linkage today and tried it out. It works!

Here's a small video (http://www.hardkore-nrg.com/servo.wmv) of it in wmv format.

[ed1380]

I still couldn't trust myself to something like that

[mikeandike]

Just watch out the wires dont get burnt by the engine. make sure they're protected.

[kibble]

Yeah, I'll make sure that there's some sort of a protective covering on the wires. I was actually thinking of running the cables through a small rubber hose or some braided wire.

I was bored at work yesterday so I started looking online and decided that I want to make my kart look like the Mario Kart karts. I finally drew up what I think it should be like after seeing various pictures of the front and back of them. The only thing that I'd probably have to modify is that the karts in the game look a lot shorter that they'd have to be for a real person.

[ed1380]

What value resistors did you use? Was your curcuit similar to the one I linked to?

[kibble]

I used the one's that were recommended on the schematic I found which were: 330kΩ, 1.5 kΩ, 15 kΩ. I'm gonna have to go and modify some of those though because the servo tries to go farther than it really needs to and I don't want the servo to break a gear on the inside or something.

The circuit you linked to was very similar to the one I built except for the fact that I used two individual 555 Ic's and the other schematic used a single 556, which is basically two 555's in one package. I could have built a smaller circuit if I had a 556 available.

[ed1380]

in the diagram it shows it as 2 555's. other than that is it the same? and where does each resistor go? value/location

[kibble]

Yes, the 556 is just like having two 555's in one package. It's not easy to describe where each of the resistors goes connected to the IC, you have to look at the schematic for that. On the schematic you can see that there are numbers on each of the wires coming out of the 556, each number represents a pin. Resistors don't have a polarity so they can be connected in either direction. The values for each of the resistors is in the schematic. 100k means 100 kilo ohms or 100,000 ohms. 3k9 is 3,900 ohms. 220 with no letter is just 220 ohms.

I have been working on my frame for the past few days and gotten better at welding in the process. I messed up a bit in a few parts, nothing too bad that I couldn't fix but, so far everything seems pretty stable.

[ed1380]

cmon I'm not that stupid ;)

I meant 300ohms for r3, 100ohms for r5, etc. The reason I'm asking is cause the one I linked to has 2 pots. one for base signal and the other for servo position. I would only like to use one pot, and have a fixed resistor for the base signal pot.

[kibble]

I'm pretty much uber stupid in electronics.

That's what you said before, I didn't question it. LOL, JK.:p

Well I don't know exactly what values would give you the best results for your servo but, what I would recommend doing is using the values on the schematic and modifying them to your requirements.

If you're asking about the board that I built then I used 330k for R1, 1.5k for R2 and 15k for R3. For the pin where it says "analog in" I connected the wiper of a 100k pot and connected the other two ends of the pot, one to ground and the other to Vcc.

If you want to have a fixed resistor instead of the pot on the first part of the schematic you linked to then what you might want to do is connect a pot first, adjust it to where it gives you what you want, then measure it with an ohmmeter and see what value of resistance it gives you. After that just find something to match what r2 and r6 add up to and you'll only be using one fixed resistor.

BTW, I'm not THAT good at electronics either. I'm sure there's probably a better way to figure out how to get proper values using math. I usually just play around with the values until something works like I want it to or 'til it bursts into flames:eek: , which doesn't happen very often.

I hope this helps out.

[kibble]

Progress has been terribly slow... I hate it that things come up when I have a chance to work on stuff, either that or it's too cold outside to be working on stuff. I will be posting some new pics soon of the stuff that I have gotten done.

[kibble]

Here's some pics of a mock up of what I eventually want my kart to look like. I just got the tires today through ups. There's a picture of one of the spindles I built and a pic of my engines shaft after I cut out the keyway. I gave my cv joints to a friend who's gonna try to machine them for my application, that's why they're not attached to the diff. Not pictured are the wheel hubs sprockets and pillow blocks that I got on ebay.

[robertdjung]

looks awesome!

[2or3wheels]

Has that fast look. Are you using pully to jackshat and then clutch on jackshaft?

[kibble]

Thank you guys! :D

Yeah, unfortunately for the time being I'm gonna have to attach the clutch to a jackshaft. I'm using two pulleys of the same size on the engine and on the clutch, the other side will have a sprocket, which I have but is not pictured either. The engine I have doesn't have a 3/4" shaft so the clutch will not fit on it directly.

[2or3wheels]

What size? I know there are ones with 5/8" and 1" too.

[kibble]

I do believe it's a 1". I will see about getting another clutch for it eventually.

[kibble]

A couple of new pics.

I put together the engine mount. I made it out of parts of the generator chassis. I also started working on the jackshaft/clutch assembly.

[robertdjung]

lookin' good

[kibble]

I have some updated pics of my kart. I got an axle for the rear and I put together a mock up of what the rear will be like. I need to buy some more square pipe. The differential is not mounted the way it will be in then end. I just took out the gears and mounted it on the axle so I could get an idea of how much room it would take up and where to put the other stuff.

For those of you wondering, yes, that is an Arrowhead water bottle in between the muffler and air filter. Why? Temporary gasoline container so I could test out the engine. I left it on so that dust wouldn't get into the filter or gas lines.

[GoAlterBridge]

That kart's gonna' fly!

[kibble]

I welded the engine mount to the rest of the frame and put the tires on just to take a pic. The rear tire on the right side of the pic isn't really attached to anything and the frame it actually being held up by a piece of PVC pipe on that side. I really like the way it's turning out!!! Unfortunately the person that was supposed to get the cv joints machined hasn't gotten back to me about them. I can't do much else in the rear until I know what they're gonna look like or how much space they're gonna take up. I still need to get me some brakes.

[2or3wheels]

The jackshaft looks heavy-duty, that thing will never have a problem moving.

[kibble]

Well I hope it moves eventually. I went and bought a belt today that will link the engine to the jackshaft. Once I get the CV joints back I'll be able to finish welding up the drive mechanism.

[2or3wheels]

Then you can test drive :D

[kibble]

Well not quite yet. I still don't have a steering mechanism either and I still need a sprocket for the differential.

[2or3wheels]

**** that must suck.

[robertdjung]

this thread is getting a little long and unwieldy... let's start anew, shall we? :)