66LED compact circuit (touch on and pulse)

Discussion in 'The Projects Forum' started by lowlyassassin, Jun 25, 2013.

  1. lowlyassassin

    Thread Starter New Member

    Jun 25, 2013
    Hello world
    I'm new first post yay, my names Lily
    I'm working on a project, it's a prop for a movie, its a 120mm sphere/ball, the circuit must be completely enclosed within the sphere

    It has to have a lot of light coming off it, so far I have 66LEDs
    In this sort of configuration
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    +----|>|----|>|----|>|----|>|----|>|----|>|---/\/\/----+ R = 1 ohms
    That's 6 LEDs in series and 10 rows
    8 AA batteries giving 12v and the baateries are rated 2000mah which gives a theoretical run time of one hour

    I would love to add a touch switch so that the circuit is only on when there is someone holding it, I have read that the touch sensors.can be made really sensitive so that the sensor can be mounted under the surface

    So that's part one of the project

    Part 2 is to get the lights to pulse so 3 rows of lights pulse off then another 3 pulse off then the remaining 4 pulse off, or for each row to pulse off one after the other

    Don't know where else I can ask for advice about this

    If I need more or less or different batteries let me know
    I have been told by a man in a shop that the only way I can power this is by DC mains power, but I don't believe him
  2. Shagas

    Active Member

    May 13, 2013
    I'm having trouble understanding your diagram , or maybe it's just me .

    What is the forward voltage drop of the led's?
    What is the sphere going to be made out of ?

    A touch switch is pretty easy to set up with some darlington transistors (or at least how I do it)
    And for it to pulse like that you will probably need a 555 timer and some digital gate circuitry or a microcontroller.

    Also why are you using so many LED's? why don't you use fewer but more powerfull ones?
    Ofc you can power the whole thing by batteries but you need the right ones
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    We need to know more about the LEDs, color, max current-size. With red LEDs , 12 V would allow about 4 in series = 17 strings. 17 strings @ 20 mA = 340 mA. 2000 mAh / 340 mA = 5.8 h. Pulsing no problem; maybe use a tilt SW so any movement would restart pulsing. I've seen styrene spheres in craft stores which come in interlocking halves.
  4. lowlyassassin

    Thread Starter New Member

    Jun 25, 2013
    I realised I did not supply the details of the LEDs
    Here are the specs
    Emitted Colour : YELLOW
    Size (mm) : 3mm
    Lens Colour : Water Clear
    Peak Wave Length (nm) : 585~595
    Forward Voltage (V) : 1.8 ~ 2.2
    Reverse Current (uA) : <=30
    Luminous Intensity Typ Iv (mcd) : Average in 5000
    Life Rating : 100,000 Hours
    Viewing Angle : 20 ~ 25 Degree
    Absolute Maximum Ratings (Ta=25°C)
    Max Power Dissipation : 80mw
    Max Continuous Forward Current : 30mA
    Max Peak Forward Current : 75mA
    Reverse Voltage : 5~6V
    Lead Soldering Temperature : 240°C (<5Sec)
    Operating Temperature Range : -25°C ~ +85°C
    Preservative Temperature Range : -30°C ~ +100°C

    As you can see they are pretty bright at 5000mcd
    I need that many as its meant to be blindingly bright and I could not think of a way of using less
    The sphere is currently made of a solid Styrofoam block (there will be an access whole cut out at the bottom, a circle that I will measure and report back in 6 hours when I am home
    It will also have magnets in the base of it as it will be using maglev technology to float on a pedastool

    Here is the sphere so far
    Last edited: Jun 25, 2013
  5. wayneh


    Sep 9, 2010
    FWIW, I use LEDs that are rated to over 20,000mcd on the same current. But this is achieved by focusing the light into a fairly tight beam. If you're on beam, even 5mA is blinding across a dark room. But if you're off axis, you can only see the light, it's not remotely "bright".

    My point is just that you should consider beam dispersion. "Blindingly bright" is in the eye of the beholder. My hunch is that the viewer will perceive the most brightness when he is within the dispersion angle of the largest number of LEDs, and I think this means you want LEDs that are relatively LESS focused than mine are. Maybe this is what you already have.

    I'd consider an accelerometer-type switch instead of a touch switch. Like a pinball table's "tilt" detector. I think it would be more reliable.
  6. lowlyassassin

    Thread Starter New Member

    Jun 25, 2013
    Thank you for the lovely advice
    Although o don't know what fwiw means but seeing as I understood the rest I presume its not important

    I did consider a tilt sensor but I do t know how use full it will be as the sphere will be free floating and rotating ( like the novelty toys you can get that appear to magically hover {it uses maglev or magnetic levitation technology}) and as such would the tilt switch not just constantly notice the movement and stay on?
  7. wayneh


    Sep 9, 2010
    For what it's worth = FWIW

    Sorry about that - I hate it when posters here use texting speech, and here I went ahead and did it myself.

    Yeah, forget the tilt switch. You want the sphere to behave differently when a human reaches in and grabs it from the maglev? I'm wondering what effect the maglev might have on the other electronics.

    Also, will this thing be off balance due to the magnets? I think, since the maglev repels the magnets, the magnets will be pushed to the top of the sphere instead of at the bottom due to gravity. Just sayin'
  8. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    Batteries' mAH ratings are based on 0.1 I x 10 Hr.... i.e a 200mA x 10Hr for a 2000mAH battery. A 2000mAH battery will run for 10Hr with a load of 200mA, but it will not run for for 1Hr at 2000mA....or for 5.8Hr at 340mA.

    Always best to check the manufacturer's discharge curves.

  9. Markd77

    Senior Member

    Sep 7, 2009
    For What It's Worth, could you just have a sensor that detects the magnetic field from the mag lev? I'm not sure if that's the effect you want you want, and I think it would only work easily if there is a chunk of iron in the ball, rather than a permanent magnet.
  10. lowlyassassin

    Thread Starter New Member

    Jun 25, 2013
    I have a lot of magnets of various sizes on there way
    I will figure out some sort of solution when they arrive
    The stand will have the magnets in a circle arrangement so the lowest magnet is held at the lowest point of the magnet field (sort of caught) and I may need other smaller magnets further up the sides of the sphere, I will know once I have gotten the magnets and began experimenting

    I'm not sure how effective that would be as I would have to get specs on how much weight the magnetic holder could support and then how big the piece of iron would have to be in order to 'float' and hope that, that and the weight of the components is under the weight the magnets can repel

    I assumed they magnets would have no effect in the electronic circuits as they will be stationery in relation to each other
  11. Bernard

    AAC Fanatic!

    Aug 7, 2008
    How long does ball need to be illuminated, thinking of ways to cut battery weight.
  12. lowlyassassin

    Thread Starter New Member

    Jun 25, 2013
    I did say about an hour

    And I am still clueless as to what components or how to wire in a touch sensor (can it handle 12v)
    And a flashing circuit would it work if I just added a capacitor? As the LEDs would be off when the cap was charging and on when it discharged?
  13. lowlyassassin

    Thread Starter New Member

    Jun 25, 2013
    So I was doing a bit of research and I can't find much in the way of how to wire a capacitive touch sensor
    Let alone the parts it uses or the maximum distance it can sense human skin

    So I was thinking maybe I should use a infrared proximity sensor but I don't know if it is possible to reduce a sensors nominal field to an inch or less to like 10mm
  14. lowlyassassin

    Thread Starter New Member

    Jun 25, 2013
    I found this schematic for a 555 chip to control fading
    But I can't see the negative voltage pin
    I do think that I could just replace the led and resistor with whatever combination of LEDs and resistors I need dependant of voltage
  15. bance


    Aug 11, 2012
    Pin 1 is Gnd on a 555 timer.... Maybe you could use a reed switch, to trigger the effects, if you are using mag-lev.

    HTH Steve
  16. wayneh


    Sep 9, 2010
    Controlling the LEDs is "so easy" that I suspect no one is even thinking about that aspect of your project. I think we're still struggling to understand the system and how you want it to behave.

    So some questions: When the ball is floating in its maglev cradle, you expect it to be dark? You want the lights to come on - and exhibit some programmed effects - when the ball is touched by a human? Can there be a specific touch spot (like a nickel-sized disc, say) or does a touch anywhere need to trigger the activity?

    Do you have any microprocessor experience? Depending on the effects you need, this could be a better approach than timers and such.

    Feed us more details and you'll get back better suggestions. ;)
  17. lowlyassassin

    Thread Starter New Member

    Jun 25, 2013
    I would like the device to be "off"/ non functional / dark when it is sitting in its cradle
    When a human gets close or touches it I would like it to be active or light up

    I would prefer no specific touch point but I feel I could add several "switches" or "sensors" or "triggers" on the device so that only one has to be triggered in order to activate the device,( I have looked into conductive touch sensors and it seems that a circuit using one of those can have multiple contact points off of a single circuit)

    I have no microprocessor programming experience

    My aim is to build this in the simplest form so just LEDs and then to add the easy stuff then the complex stuff
  18. RichardO

    Well-Known Member

    May 4, 2013

    Maybe this link will help:
  19. elec_mech

    Senior Member

    Nov 12, 2008
    I recently made an LED batlight that comes on with the touch of a piece of metal, plays music, and slowly fades the LEDs from bright to dim to off as the song plays using a small PICAXE microntroller. At some point I'll post it in the Completed Projects section here at AAC. This is a long way of saying I think I can help. :D

    Let's go over your requirements again:
    1. Ball will float using some form of magnetic levitation - while floating (stationary and untouched), electronics will be off.
    2. Multiple LEDs will be wired in rows and each row (or certain sets) will be flashed/pulsed/faded independently of the others.
    3. LEDs will come on once ball is touched and/or motion is detected.
    4. Circuit will be powered by batteries and batteries must last at least one hour with LED lit before needing replacement/recharging.
    5. Device is being used as a movie prop.
    Is this correct?

    If so, here are some questions:

    With regards to item 2, you've mentioned flashing and later fading. These are different actions. You've also said the ball would come on if someone comes near it or touches it. Can you go through, step-by-step, what exactly the LEDs will do through the course of the "scene"?

    Here is an example:
    1. With no one near it, ball is floating above its stand and LEDs are off.
    2. Someone approaches ball and does not touch it. When person is xx distance (inches, feet, meters?) away LEDs do something (flash, fade from dark to bright, come on full brightness instantly, etc.).
    3. When someone touches ball, LEDs do something (flash, fade, etc.).
    4. LEDs continue doing this thing while ball is touched (or do other things depending on how long ball is touched.
    5. LEDs then do something else when ball is placed back on stand.
    6. LEDs then do something when person is xx distance away from ball.
    We need to know exactly what it is you want to happen when something is done (ball detects motion, ball is touched briefly, ball is touched for xx time, ball is placed back on stand, etc.). This will help us come up with options for you.

    Off the bat, I'd suggest wiring the LED strings or set of strings to a logic-level MOSFET each and controlling everything with a PICAXE microcontroller. These are relatively cheap and you can easily program the LEDs to do whatever you want. Additionally, it is real easy to use any piece of metal as a touch sensor with the PICAXE.

    You could use multiple pieces of metal for multiple touch sensors, but this can get tricky depending on how many touch points you want. Because this is for a prop not necessarily an actual product such as a children's toy, I'd find out how the ball will be used in the scene or scenes. Unless the ball is being thrown between individuals, it would be MUCH easier to use one or two touch sensors and tell the actor to make sure their finger is always on the touch sensor. Another thought is to time the duration of the LEDs - if you know the ball will need to be lit for at least 10 minutes after it is touched, program the LEDs to stay on for 10 minutes instead of worrying about the actor moving their hands around the ball. You can add another OFF touch sensor the actor touches as the ball is placed back on the stand as an override (then the timing doesn't need to be perfect).

    If you want to avoid programming, you can hardwire this using a 555 in stable mode and a 4017 to scroll through the rows of LEDs. If you need more timing options or want the LEDs to fade, then you'll need multiple 555 circuits. The advantage of the microcontroller is a smaller board and the ability to change the display on a whim including flashing and fading. I can write a program for you if you'd like (as long as you don't need it too soon).
  20. lowlyassassin

    Thread Starter New Member

    Jun 25, 2013
    Ball will float using some form of magnetic levitation - while floating (stationary and untouched), electronics will be off.
    Multiple LEDs will be wired in rows and each row (or certain sets/combinations of rows) will be pulse (fading from off to on to off independently of the others.
    LEDs will come on once ball is touched and (not when motion is detected as it will be free floating and prone to rotating)
    Circuit will be powered by batteries and batteries must last at least one hour with LED lit before needing replacement/recharging.
    Device is being used as a movie prop.

    We will be making two versions of the wiring one will simply stay one at all times and I do not need help with that one
    The other, will go from being off in a stationary floating state
    1 As the person approaches it does nothing until they either
    2A) get within inches of the device( which can be simulated easily with post production effects once we have a pulsing version working ,so isn't really an issue)
    2B) touch it and pick it up while they are holding it, it will pulse (we will trial 2 pulsing /flashing versions, one with all light pulsing in unison and another with certain rows or sets of LEDs pulsing / flashing
    3When placed back in "cradle" or person stops touching it (throws it up in the air with one hand and catches it like a baseball/tennis ball
    /passes it to another person like a baseball/tennis ball) it is off while it is in the air but turns back on /resumes flashing /pulsing when caught

    With a pulsing version and a constant on version we will be able to cover all uses we need in the one scene

    So the flashing / pulsing / fading i only see as one function, but I may have described it wrong,

    If you need more information then let me know