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SCALE MODEL LEDS FROM AC POWER SOURCE

Discussion in 'Power Electronics' started by jzetty84, Jul 29, 2019.

  1. jzetty84

    jzetty84

    3
    0
    Jul 29, 2019
    Hey Guys, new here. I've got a little project I'm working for my sons room and I need a little help on part of it. I'm going to be putting in a helicopter ceiling fan using an 1:6 Model Helicopter (Little Bird from Ultimate Soldier toy line). Ill be attaching the base of the rotor blades to the bottom plate of the fan so that the fan blades become the props and it looks like a real helicopter. I want to add some scale model LED nav lights to the helicopter so that they go on when you turn the fan on. That being said, I'm still working on getting the exact specs on the nav lights, but they are rated to run on 4.8v-9.0v DC power (not sure on the total amp draw though). Obviously I'm not running DC power in this set up, so I need to run an AC to DC transformer or converter so that the LED controller is getting the correct power it requires. I would prefer not to use a converter that you just plug into the wall, as that would require running a separate outlet on the fan circuit and have both wired to the switch that I'm adding to the wall. Is there a good in-line transformer that I can wire directly into the ceiling fan lights (which are getting removed and replaced with the helicopter) and use that to power the LED controller from there? Below is a link for the nav lights I'm looking at using... Any ideas or input would be much appreciated. Thanks!

    LED NAV LIGHTS AND CONTROLLER
    https://www.scaleflying.com/Scale-LED-Lighting-System-for-RC-Helicopters-Airplanes_p_17.html
     
  2. Alec_t

    Alec_t

    2,682
    710
    Jul 7, 2015
    Welcome to EP!
    Something like this perhaps? It comes with a mains lead from which the mains plug could be cut off.
    Alternatively (but somewaht clunky) you could use a AC/DC adapter of the plug directly into mains outlet type and buy a mains socket to mate with the plug. That socket would have accessible wiring terminals.
     
  3. Martaine2005

    Martaine2005

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    May 12, 2015
    Also don't forget the 'slip ring' that is needed while the blades spin as the fan.
    Note: you will need to probably change the rotors or soften them to put a positive pitch. Pushing the air down.

    Martin
     
  4. Alec_t

    Alec_t

    2,682
    710
    Jul 7, 2015
    So how is the heli fuselage supported such that it doesn't rotate with the blades?
     
  5. Martaine2005

    Martaine2005

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    May 12, 2015
    My guess is fishing line, transparent fore and aft.

    Martin
     
  6. dave9

    dave9

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    Mar 5, 2017
    Contact the seller (or manufacturer) to find out the total current draw.

    You might be able to just repurpose a 5V/USB cell phone charger, not plug it into the wall but rather pop it open (in a vice or clamps or hot knife melt the seams, whichever) pull the wall socket blades off, solder your wire to that then run that wire to the wire nuts in the fan for its (former) lights.

    You might already have an old cell phone charger or could buy one new. I'd measure the space in the rear of the cockpit of the heli to see if it'll fit in there. You can find fairly small 2 amp capacity on ebay for around ~$3 and up, delivered, though I leave it to you to determine which you can more easily, non-destructively open, unless you prefer to just solder wires direct to the outlet blades and have the dimensions be larger, but if you get the blades too hot and they desolder from the internal circuit board while soldering wires on, you'll be cracking it open anyway. I suppose you could devise some way to use a brass crimp, but generally I find such casings pop open without too much trouble with pressure applied to the corners in a bench vice while being split at the seam with a wood chisel.

    Unfortunately I suspect that you will find that using the original (or similar size) heli blades on a ceiling fan will produce an inadequate amount of airflow, but I may be overgeneralizing based on "most" ceiling fans while there are some that spin at much higher RPM than others.

    I also wonder if the blades themselves can withstand this since it is just a model, not an R/C heli with blades designed to withstand high RPM, but this suggests a solution in itself, to get R/C heli blades.
     
  7. Bluejets

    Bluejets

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    Oct 5, 2014
    A fan/light arrangement would be a simple "fixing point" as the centre shaft of the fan extends though the centre of the base bearing.
    Usually a thread around the size of an auto car radio pot fixing (3/8")

    That would suspend the body ok BUT getting power to any spinning LED's on the blades would be a real nightmare as in a ceiling fan the "rotor" is a sort of back-to-front arrangement where the powered stator is on the inside and the rotor laminations are on the outside.

    Easy to say, add slip rings, quite another to implement.
    No room inside those fans to do any mods let alone what would be required.
    Also it would require isolation of any low voltage wiring from the internal mains supply, almost impossible.
    This is all before even considering the requirements for any mods to mains connected equipment by a local authority.

    Just hope the kids don't have any problem with flashing lights at any particular frequency. I know from experience of fan installs that even cutting the light beam from existing ceiling lights in the room is to be avoided like the plague.

    In the 90's there was a fan introduced called a "decorator fan" the purpose of which was to "look like a fan". Pushed next to zero air and the trend lasted obviously no time at all. ( go figure)
    This with the heli blades would be next to zero air as well as already noted.
     
    Last edited: Jul 30, 2019
  8. jzetty84

    jzetty84

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    Jul 29, 2019
    ya I was looking at those as well! I guess if I get one with a standard grounded plug, I could cut off the plug and wire that to the fan light hot/neutral/ground. Then either cut the other end off and wire it to the led controller or find a connector.

    As for attaching the helicopter to the fan, it's much simpler than that. The heli is just a plastic toy in 1:6 scale. Basically a huge GIJOE toy. You just take the rotor blade assembly off the top. Then take the cover plate off the center of the fan where you can add a light fixture. Screw the fan plate to where the rotor assembly used to be on the heli, then place the heli with the fan plate up to the fan, twist the plate until it locks and then your done. So now the fan blades take the place of the rotor blades and when you turn it on it looks like the real thing. See YouTube video below.



    I'm just adding nav lights to make it a cool night light for him.
     
  9. Bluejets

    Bluejets

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    Oct 5, 2014
    Well then, if you know so much about it, why ask?
    Appears you'll go with what you decide regardless of any advice.
     
  10. Martaine2005

    Martaine2005

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    May 12, 2015
    NAV lights don't spin on the blades..
    Why? this is done in the model. not the fan.
    Why?
    Again, why?
    These are LEDs not strobes..

    As quoted
    I think that sometimes we all need to read the op's question.
     
    Harald Kapp likes this.
  11. jzetty84

    jzetty84

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    Jul 29, 2019
    Bluejet, where in any part of my response did I suggest that I know more than anyone else here and that I had already decided my course of action despite the advice that I was seeking in the first place? I was simply making sure I understood what ALECT had suggested by clarifying what he was suggesting. Additionally, my only question was for ideas on how to tap into a ceiling fan power supply and convert 110v AC to 9v DC to power a set of small LED lights, not how to attach the whole thing to the fan itself, which you seemed to assume you knew exactly how I was going to be doing it, when in fact that was not the case at all. So if already having a plan for attaching the helicopter to the fan offends you, well that's your problem because that was never my question to begin with.

    That being said, the USB charger is a good idea and I have a bunch lying around so I appreciate the suggestion dave9!! Never thought of that! Couple questions. 1. Does the polarity matter in regards to which wire I put on which blade seeing as I believe usb chargers are the same size blade on each side... 2. Are usb chargers regulated or not? Or does it even matter? I don't think these lights will draw an amp in total, so I just don't want to put the whole thing together and fry them.. Thanks!
     
  12. Martaine2005

    Martaine2005

    2,394
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    May 12, 2015
    You are correct in that the base plate does not spin, so very easy to mount the chopper. No slip ring required.
    The fan in my loft is on a shaft and the whole blade assembly spins.
    All you need to do is buy an AC/DC adapter of the required voltage for the controller as dave9 suggested. Mount it in the fusilage.

    Martin
     
  13. dave9

    dave9

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    186
    Mar 5, 2017
    USB phone chargers are not polarized, remember it's an AC input, and are a regulated output, but no if the lights' spec is correct and they take a wide input range of 4.8V to 9.0V then you don't need true regulation per se, would just need the resultant voltage to fall within that range.

    HOWEVER, if what they mean is that each LED is just in series with a resistor, you would get less light the lower the input voltage is towards 4.8V, or conversely you might not get good lifespan out of them if ran too close to 9.0V input... depends on how conservatively they were rated. They really should have provided this data, can't imagine what they were thinking in not doing so. This also means that if they just use a resistor in series that you could swap in a different resistor to vary the drive power, staying within the limits of the LEDs.

    A USB phone charger should have the regulated voltage and max current labeled in tiny text that you may need a magnifying glass to read. Older chargers may only be capable of a few hundred mA, so to have a fair current margin it would be good to know the current draw of the LEDs but you can hook them up to a higher current capacity bench supply at 5V to measure that.
     
    Last edited: Jul 30, 2019
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