chrism Posted April 26, 2008 Share Posted April 26, 2008 Hi guys Im after a couple of proximity switches so i can tell when my rear steer is in the centre. Anybody know of any suppliers in shropshire/cheshire? Also anybody got any set up pics that they have done? I am planning on fixing something like a handbrake cable onto the axle and hub, then run it to a small metal box in a safer place, then use the cable to slide a bar with 2 lugs on it back and forth. Then set the sensors up so they pick the lugs up. The proximity sensors i have seen have a face about the size of a 10p so would they open up and put my light on as soon as they come into contact or would the whole face of the sensor have to be covered before it switches my light on? Cheers Chris Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 26, 2008 Share Posted April 26, 2008 If you use a hall effect sensor they are sealed and can be mounted direct to the axle, all they'd need is a bit of metal that is under the sensor when the steering is centered. RS components sell them, they're everywhere. Quote Link to comment Share on other sites More sharing options...
chrism Posted April 26, 2008 Author Share Posted April 26, 2008 This is the type of thing i have seen before, we use something similar for the height restrictors we put on minidiggers that go into low buildings. Looks like it would do the job, what do you think? http://uk.rs-online.com/web/search/searchB...t&R=1807363 Quote Link to comment Share on other sites More sharing options...
steve_d Posted April 26, 2008 Share Posted April 26, 2008 If you are going to use the cable then having it push a magnet beside a read switch will do the job. Screwfix window/door security switches are 99p each (made by Honeywell). Parts 24918 or 76045. Steve Quote Link to comment Share on other sites More sharing options...
m&mv80 Posted April 26, 2008 Share Posted April 26, 2008 why dont you use a sender and guage, that way you can see where the wheels are pointing at all times not just when centered, still use the cable idea to keep the sender out of the mud though , boats use the same idea and its called a 'rudder reference' guage if its any help just a thought Quote Link to comment Share on other sites More sharing options...
steve_a Posted April 26, 2008 Share Posted April 26, 2008 A bit of a suggestion, if you take a windscreen wiper cable and attach it then set that to twiddle a simple pot you have a varying voltage dependant on rear steer position. You could then run a series of LEDs off it which would give you an indication of not just when in the centre, but also how far you have it turned. I haven't been fiddling with electronics lately but I don't think it would be a very complex circuit to light bars up, your full scale could easily have 20 LEDs (assuming 0.6v drop per LED) and would provide a vaguely nice analogue display. Might have to fiddle for the right gear size to make the pot go full swing with the steer of the axle. Good side is all the parts are pretty cheap and easy to make and replace. You can go to electric pretty quickly and the cable should be pretty resilient to allowing any muck back into a box with the pot in. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted April 26, 2008 Share Posted April 26, 2008 Bloody hell, those sensors are expensive!!! I'd go with a pot, if you want analogue data, a hall effect sensor on the axle sounds groovy. Or, you could use photodetectors/IRLEDS and a bar with a hole in it, total cost of the sensors about a quid. There's a thread on pirate where they guy just used microswitches. Quote Link to comment Share on other sites More sharing options...
najw Posted April 26, 2008 Share Posted April 26, 2008 This how I did mine. The upper tube travels in sync with the ram and the prox sensors at either side detect where it is. If you are using an electronic valve body you can then add a re-centering circuit so when you push the joystick forward the rear wheels automatically re-centre Quote Link to comment Share on other sites More sharing options...
steve_d Posted April 26, 2008 Share Posted April 26, 2008 If you want the line of LEDs to give position you could line up a bank of read switches which will light LEDs as the magnet passes. Steve Quote Link to comment Share on other sites More sharing options...
AndyEvans Posted April 26, 2008 Share Posted April 26, 2008 i would personally use those sensors mentiond but they need to be placed about 0.5mm away from what they pick up on to be acurate. but they are easily damaged which make them stop working completly. there are a choice of npn or pnp sensors avalible. if there wired up wrong u will also damage them. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted April 27, 2008 Share Posted April 27, 2008 We use Hall effect sensors at work - they take a lot of abuse and very rarely fail. They do however need to be quite close to the part in question.... Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 27, 2008 Share Posted April 27, 2008 You could then run a series of LEDs off it which would give you an indication of not just when in the centre, but also how far you have it turned. I haven't been fiddling with electronics lately but I don't think it would be a very complex circuit to light bars up, your full scale could easily have 20 LEDs (assuming 0.6v drop per LED) and would provide a vaguely nice analogue display. This circuit will do exactly that - you can chain 3914's indefinitely if you want to give 20, 100, 1000 LED's if you really want. A Range Rover air suspension potemtiometer would work, it's just a pot with an arm on. A bit easier to seal than a rack & pinion style too. Quote Link to comment Share on other sites More sharing options...
chrism Posted April 27, 2008 Author Share Posted April 27, 2008 Im liking the led idea, but im not good with things like that! Does anybody make and sell kits for that type of thing? I wont be using it as a self centring circuit, as i have a loadall style set up with a manual change over valve to go between 2, 4 and crab. I just want to keep it as simple as possible, so if the wheels do end up out of line im in control and can line it up myself rather than having to fiddle with leccy things etc Quote Link to comment Share on other sites More sharing options...
steve_a Posted April 27, 2008 Share Posted April 27, 2008 From the looks of it, a few beer tokens to FF would see you right Love the comments, You went digital while I still tend to think about analogue, but if you get such fine resolution with FF circuit then that is definitely the way to go, less susceptible to voltage loss issue probably. If you throw a PIC at it you could make it auto calibratiing too Quote Link to comment Share on other sites More sharing options...
red90 driver Posted April 27, 2008 Share Posted April 27, 2008 Chris - I should be able to sort out some telemechanic prox sensors that we use in work. Will have to check if they will work on 12v cos we use them on 24v. I can let you know properly tomorrow. They require about 1-2mm sense distance, but are plastic bodied so are fragile. Euchner do some metal bodied ones with a bigger sense distance (up to 5mm) but I can't "source" any of those at the moment. These sensors have 3 wires - +v, -v & switch and so are dead simple to wire. Will give you a ring tomorrow. Cheers - Nick Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 28, 2008 Share Posted April 28, 2008 From the looks of it, a few beer tokens to FF would see you right Love the comments, He's not wrong Quote Link to comment Share on other sites More sharing options...
chrism Posted April 28, 2008 Author Share Posted April 28, 2008 Hey up nick, hows things! never seen your face on here before! Switches sound good, they dont need to be too robust as im not mounting them on the axle, going to put them in a box up near the tray back somewhere i think, as long as they can stand a bit of water/carp then im sure they will be fine. Chris Quote Link to comment Share on other sites More sharing options...
chrism Posted April 28, 2008 Author Share Posted April 28, 2008 also guys, what do you mean by a pot, i have never heard of or seen them before! Any pics or links? Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted April 28, 2008 Share Posted April 28, 2008 Pot - potentiometer - variable resistor, see wiki link Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 28, 2008 Share Posted April 28, 2008 ^^^ What Luke said - what all volume knobs used to be before stuff went digital. Quote Link to comment Share on other sites More sharing options...
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