stuartglen Posted April 14, 2006 Share Posted April 14, 2006 At my school we have a smoke machine, I have been asked to build a radio control for it. The way it works is this A radio reciever is powered by a 5v transformer, this is connected to a serve, the servomoves and connects two electical contacts, allowing the 10v control voltage of the smoke machine to flow. All materials insige the plastic tub are non flamable http://www.aux99.co.uk/blue-room/100_1345tn.jpg Click Image for Hi-Res version anyone see any problems with this setup? :)Could people please NOT post hi-res pictures directly to the forum. If you have a hi-res image then use a thumbnail and make it clickable.:) Link to comment Share on other sites More sharing options...
jayselway Posted April 15, 2006 Share Posted April 15, 2006 What about looking at Maplins or somewhere similar for a radio controlled switch, with relay output, that you could use to switch the trigger on your smoke machine. Just a thought, but I can't see why having mechanical servos will actually help - as they seem to be a bit of a "middle person" on the project.... Although being able to change the crystals on the set up you have might be useful - that annoying kid with the radio controlled car might be a factor - or maybe a local boating pond :) Also, if you put your reciever in a suitable box, then you could use a magnet to hold it to the back casing of the smoke machine - Antari used to do one that had a radio remote available for it, the receiver for which just plugged into the back, and stuck to the side / top / anything magnetic nearby! If you have a remote input (low voltage) on the machine, then it may put out some power to supply it's controller / receiver with - which would mean you don't have to use batteries - which would also stop the servo from failing in the "on" position - if, as sometimes happens, the servo's start to twitch as the batteries run down.... The Antari remote had a nice little keyfob with two red buttons on it... Stylish too!! HTH a bit Jay :) Link to comment Share on other sites More sharing options...
stuartglen Posted April 15, 2006 Author Share Posted April 15, 2006 the reciever is powered off a 5v transformer so the batteries aren't going to run out since the unit is powered off a 5v transformer. It is very unlikely that I will get radio interferrence since a) it is on an aircrafft frequency band, b) it is a non standard frequency that is little used and c)it will be used after dark so no one in their right minds will be flying. I will not interfer with anyone else since I will keep the arial down, limiting the rang to <100 yardy. My post was to see if anyone could see any safety problems with this control. All it has to do is control a smoke machine cheaply, it doesn't have to look pretty. I built this device with safety in mind but I may have overlooked something. I don't want to burn down my school. Anyone see a safey problem? Link to comment Share on other sites More sharing options...
paulears Posted April 15, 2006 Share Posted April 15, 2006 apart from the obvious safety concerns about switching mains, I don't see any real problem as if it suddenly goes off, all that happens is that somebody will pull the plug out. RF in, servo moves and actuates the smoke works, and I guess you had the kit. I would have thought that you could cut out one stage by having the dc to the servo motor simply operate a small relay closing the'operate' button - but if it works....... Even if somebody does fly a plane at night, over your device - the worst thing that can happen is it goes off on its own, or maybe refuses to go off if your 'smoke' command doesn't get through. My concern is that you have a damn great box with joysticks and knobs just to make a smoke machine spurt- this end is where I'd have an issue, just from the practicality aspect - but if it works for you, so what! Link to comment Share on other sites More sharing options...
jayselway Posted April 15, 2006 Share Posted April 15, 2006 True, true.... Out of interest which frequency range are you using? There used to be regulations concerning the use of model aircraft frequencies at a non elevated level - I read it in a radio control magazine some years back - don't know if it is still the case.... Good luck with the project! Link to comment Share on other sites More sharing options...
Tomo Posted April 15, 2006 Share Posted April 15, 2006 a) it is on an aircrafft frequency band,Which makes it illegal.Sorry! In the UK, the 35MHz band is ONLY for the remote control of model aircraft. Nothing more, nothing less.Particular exemptions are available for short periods on payment of a fee to some government agency or other (never looked into that) If you get caught, you will be fined. You MUST be on either the 40MHz or 27MHz band. Link to comment Share on other sites More sharing options...
Captain Posted April 15, 2006 Share Posted April 15, 2006 ...........anyone see any problems with this setup? Not a major problem, but using an alternative to crocodile clips would be sensible. They're notoriously unreliable and chew whatever they're connected to. (Found this out the hard way when I was doing my university project). Great for classroom electronics to make little light bulbs come on and measuring stuff. Not so good for the real world. Chocolate blocks/ screw terminals are your friend :) Maybe I should be posting my hatred of croc clips in pet hates <_< Link to comment Share on other sites More sharing options...
stuartglen Posted April 15, 2006 Author Share Posted April 15, 2006 I'll change to a different frequency then any particular one I should use? Link to comment Share on other sites More sharing options...
jayselway Posted April 16, 2006 Share Posted April 16, 2006 27 MHz or 40 MHz. There are different specific frequencies in these bands, which allow you to use the set legally. 27MHz is cheaper in the outset, but as a result, you can find more people using it. However you can buy different crystals which you change (in pairs) to move away from a frequency which may be in use by someone else. You can do this with 40MHz too, but you can't use a 27MHz Crystal in a 40MHz and so on (unless radio sets have changed to allow this, but I don't think so). When I used to make model boats, and used 27MHz, I often found that a kid would run past, frantically chasing his remote control car, which was just doing it's own thing cause of other 27 MHz users. Similarly, my boat crashed into the edge of the pond a couple of times cause of the kids!! Sorry - nearly <_< then!! You could still try a 433MHz kit from Maplin (of course other electronics retailers are available :)) Link to a Radio Kit Link to comment Share on other sites More sharing options...
Tomo Posted April 16, 2006 Share Posted April 16, 2006 I would recommend getting a 40MHz exchangable crystal set - Hitec and Futaba are good brands.Your existing 35MHz set cannot be changed to 40MHz(sets exist that can be changed, but given that you've asked this question you don't have one) You are only using one channel, so a two-channel set would be fine.Expect to pay around £80 for a set (transmitter, receiver, a pair of crystals and servos) When you buy a full set, it usually comes with crystals - ask the supplier to change these crystals to something other than 40.665.40.665 turns up in almost every retail set sold, so the chances of you getting interfered with are rather high!Most of my gear is at the high end of the band - 40.785 and up - and I've had very few problems with having to exchange crystals (thankfully - it's very fiddly to get to the crystal in BuzzAnt!) Sets of crystals cost around £10 a pair, so it may be worth buying a second set with a very different frequency to the first. Link to comment Share on other sites More sharing options...
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