Olly P Posted May 28, 2009 Share Posted May 28, 2009 Sorry was being stupid. would have to be in series if it is a kickback voltage! Edited By Newbie/oldie on 28/05/2009 12:01:07 Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 28, 2009 Share Posted May 28, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Olly P Posted May 28, 2009 Share Posted May 28, 2009 ah, that makes sense. Circuit V3 is as v2 but with diodes in parrallel, not series! won't re-draw in word, will wait until i get home and redraw it properly. (next week sometime) Quote Link to comment Share on other sites More sharing options...
andy watson Posted May 28, 2009 Author Share Posted May 28, 2009 erm...........I've created a monster! I only want a nice little white light! Just so Phil has the same info Olly has- it's an IC plane, with a 6V main flight pack. It will also have a 3s LiPo to power the siren. It seems sensible to me to use this as the power source for the light too. Phil, I think the 12V LED I was talking about were actually exactly as you suggest- a 5V LED with the correct resistor already fixed in place to run it off a 12V battery. Quote Link to comment Share on other sites More sharing options...
Olly P Posted May 28, 2009 Share Posted May 28, 2009 Andy, I like little projects like this, and when finished it will be small and light too. the above designs simply mean the flight-pack will activate the landing light and it'll stay on until the master switch is flicked or the battery pack is disconnected - I might make it a simple push button reset. Quote Link to comment Share on other sites More sharing options...
Peter Beeney Posted May 29, 2009 Share Posted May 29, 2009 Gentlemen - I’ve just picked up on this thread and I wondered if I could make a couple of observations, hopefully without butting in. Leaving aside the pros and cons of a direct connection of any miscellaneous devices to the receiver battery, and I wouldn’t compromise the radio system by doing that, but that’s purely my own personal choice, why not simply switch the 12v supply to the two items. Could you not do this using a complete, normal servo and a micro switch? Then it simply becomes a mechanical job. Maplins do a few such items, the GW69A at 99p looks good. Will switch 2A, plenty of scope. Don’t know the weight, but it’s surely only a few grams. Mount the switch so that the arm operates the lever at full travel. You might need to be reasonably accurate here, making sure the servo is not stalled etc. The switches require very little effort to operate anyway, and with a bit of ingenuity you could build in a small degree of adjustment. Or you could mount it remotely, operated by a push rod perhaps. Indeed, if you don’t ever want to turn the siren and the landing light on together, you could have the other switch at the other end of the arm travel, operated by a tx rotary switch, or a 3 position lever switch, if you have one on the box. An alternative, slightly up-market answer might be to substitute reed switches. And they are really light! They are just small sealed glass tubes, with contacts inside, operated by bringing a small magnet near them. Again the engineering might have to be fairly precise, but because there would be no load on the servo you would have a degree of tolerance. For instance, you could make a longer servo arm, or a tailor made shape, glue the two little magnets on the ends and you’re in business! Maplins, CL38R, £1.29, switching 1A might be a fair bet. Or the N31AN, switching 2A, at £2.29, perhaps. Magnets from Maplins, £1.49, too. Now you’ve got 12v to the landing light, you’ve got a bit to play with. And you don’t have to consider the rx pack. I’ve have thought, for a landing light, you’d need a nice, bright, white light. I think I would be looking around for the brightest I could find. Incidentally, it is possible to make a small and very light electronic switch, using an op-amp. This is probably the most elegant solution, but you do need to be very familiar with a soldering iron. And a multimeter. I saw a design years ago, so I made one. As it so happens, all the component values I used were completely wrong, ‘cos they were all I had on the bench at the time. But, stap me, it worked! I was so surprised I nearly bought my own beer! By using a good quality output FET it could be used to switch quite a few tens of amps. Hope this is a positive?? suggestion. PB. Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 29, 2009 Share Posted May 29, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
andy watson Posted May 29, 2009 Author Share Posted May 29, 2009 Thanks for those ideas Peter. From what you have written, I think I would go the reed switch route if I had to do this myself. Fortunately I think Olly is having a go at knocking something up for me. Having said that I hope the discussions carry on- to make sure the next person that decides the need a landing light can find the info they need! The reason I would have gone the reed switch route is because it could translate an electonics problem (which I have no real idea about) to a mechanical problem (which I have much more idea about. The micro switch would be (I think) very difficult to get right. It would need a lot of EPA adjustments and might be sensitive to the vibrations of the plane. Nothing that couldn't be worked around, but the reed switches would be more forgiving in my opinion. I also really like the 3 way switch tx comment- I like elegance in design, and this would be very efficient use of the channels. Having no idea what an op-amp is, I can't comment! Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 30, 2009 Share Posted May 30, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Peter Beeney Posted May 30, 2009 Share Posted May 30, 2009 Andy, Thanks for the reply. So then, for the next person that wishes to shine a little light into his electrical darkness, I’d have to say that I think there would be very little difference in installing either system. In fact, the lever operated roller version may be the better option regarding the micro switches, they are used in many varied applications, and with helpful functions like ATV on the tx controls you’d get lit up in no time at all! Vibration is never going to be a problem, with either set up, if it were, the tail-plane has just been shaken off anyway! Just to continue Phil’s theme awhile,or should that be Polyamplified, maybe even Polytwyceamplified, the op-amp was originally designed for the early computer industry, I believe, but it’s now become one of those universal gizmos that everyone finds a use for. In my case, I was using it as a comparator, comparing two voltages. It’s rather good at this, it will change state, i.e. switch on and off, or more strictly, go high or low, with a change in voltage level, or differential, of just a few thousandths of a volt. Or even just a few millionths. You can find it at the heart of your actual voltage regulator, the somewhat oddly named BEC, so beloved by all the aficionados of electric flight. I had in mind a switch for on board glow, you can build in some hysteresis, which is the lag between you doing something and something actually happening. In my case, that can be a long time. It was intended that it would turn on the glow at low throttle, but not switch it off until the throttle was more than half open, or so. I never did get around to it, though, and now, of course, you can buy commercial units that do that, and more. I think that op-amps, like many other modern electronic components, are generally very precise, have a working life almost to infinity, and as is oft quoted, as cheap as chips. They also seem to be almost unbreakable, within their operating parameters, and indeed, sometimes even substantially outside those limits. Good Luck with your endeavours. PB. Quote Link to comment Share on other sites More sharing options...
andy watson Posted May 30, 2009 Author Share Posted May 30, 2009 Well I am officially out of my depth now. I'm looking forwards to seeing what Olly is making up, and a guy at our club is building a chipmonk with lights, so he is bringing his rig to the club meeting on monday for me to look at. I will keep everyone up to date on what happens! Quote Link to comment Share on other sites More sharing options...
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