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LEDs Parallel or Series

Discussion in 'LEDs and Optoelectronics' started by CodyF11-13, Sep 16, 2015.

  1. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    The goal of this circuit is to make a large amount of LEDs flash on and off repeatedly. I have been told so many things and just been running around in circles.

    What would be the best option to power my leds in my circuit.

    I feel the 3x leds in series and have them in parallel with one another would do fine.

    But I have been told I should try 3x in parallel with a resistor bunch of them 3xleds in parallel with one another. Told this would be the best thing to do, but I plan on using this in my car only when it's running but if I were turn it off I do not want it just run my car dead in few minutes. Tell me if I'm wrong, but wouldn't this option require more current?

    I tired the parallel-parallel option and it works but resistors are getting warm they are 1/2w resistors only two minutes of testing.
    The series-parallel works, and the resistors do not get warm at all.

    Image below Is part of my circuit to give a idea what I'm trying to do.

    I showed only the series-parallel in this photo. Total amount of LEDs about 200. The LEDs are blue 5mm 3.4v 20mA each
     

    Attached Files:

  2. AnalogKid

    AnalogKid

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    Jun 10, 2015
    The series-parallel approach in your schematic is the best way; stay with it. There are more complicated ways that would increase efficiency, but what you have is an excellent starting point. What is the value of the current limiting resistor in the LED strings?

    An input voltage surge, negative transient, or reverse power connection might wipe out diodes D1 and D3 before the fuse blows. A better way to protect your circuit is to reconnect D1 as a series diode. In fact, five 1N4004's are cheap, one for the timers and one each for four group of 16 strings. This keeps the diode current below 50% of its rating for long term reliability, and gives you 200 V reverse transient protection.

    Not necessary, but an option to consider is a voltage regulator for the timers, a standard part like an LM317 or 7805, 06, or 09. Note that the LEDs can be connected directly to the input, and do not have to be powered through the regulator.

    Add a 0.1 uF capacitor at each 555 from Vcc to GND for power supply decoupling.

    Powering one timer with the output of another timer is ok, but not the best way to do things. Better to have both timers powered continuously, and have the first one's output enable the second through the Reset pin. If the control signal polarity is wrong, there are ways around that.

    What is it you are trying to achieve? That is, what are the frequencies of the three 555 circuits and why are you taking this approach. I think I know, but I want to hear your idea.

    ak
     
    Last edited: Sep 16, 2015
    Arouse1973 likes this.
  3. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    Im going look in to that thing you said about keeping the circuit safe thanks.

    I have yet pick the resistors because I'm having hard time doing the math. A online calculator for it says one thing my math says another.
    I had to say I would go with 220 ohm 1/2W for the 5mm LEDs

    Reason I have three 555 timers. Because I have two flash patterns/frequencies
    Using a on-on switch to switch between them.
    I took video if you want take look at what its doing.
    Since I don't have all the resistors I used some 1watt leds to show my work.

     
  4. Martaine2005

    Martaine2005

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    May 12, 2015
    Hi cody, one of the admins here has done a resource section for all things led.
    It will answer all your questions and more.. Have a read here.
    You wont be dissapointed.

    Martin
     
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    May I ask where on your car these LEDs will be located?

    Chris
     
    Martaine2005 likes this.
  6. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    Thank you Martin I'll give that a good look over as well.
    And Chris, The lights going on top of the car sealed in a flat rectangular plexiglass box.
     
  7. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    In some states blue is used by volunteer firemen in others, like mine, it's strictly used by law enforcement and I do mean extremely strictly.

    Chris
     
  8. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    My state blue lights are for volunteer fighters. I'm one with a permit to use it. I got one right now but its a halogen one and at night that thing looks green. I just don't have the money go out buy some $300 lightbar so trying make one.
     
  9. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Just a suggestion but a dedicated (In-Line) fuse would keep your circuit independent of the OEM fuse block. This way an over current condition would not take out any OEM devices.

    On another point, I watched your video and thought wouldn't it be cool to automate that (flash pattern) toggle switch?

    Chris
     
  10. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    Could you please tell me what you mean by automate the flash pattern, toggle switch?
     
  11. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Instead of manually throwing the switch (as seen in your video) you can include another timer that switches the flash pattern on a timed basis.

    Chris
     
  12. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    That would be very nice. I feel like I would know how to do it but tell me if I'm wrong.

    Same way you would set up a 555 timer to make alternating leds.
    But with the positive to the 555 timer with the single flash. And hook the negative to the 555 with the triple flash.
    The 555 timer giving them power with a flash rate of once every 5 to 10 seconds?

    If wrong please show me by editing my photo. I do better with photos than written instructions.
    Thank you

    Photo below
    \/
     

    Attached Files:

    Last edited: Sep 21, 2015
  13. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    It would be good practice to label (component number) all components on your schematic. This way we can refer to them IE .. Rn, Un, Cn, Sn, etc.
    Anyway I would rethink that circuit. Bringing the GND pin of the 555 high would not be considered orthodox and will probably drive the FET nuts.

    Here's a clue of what to do.. Think Reset pin. ;)

    Chris
     
  14. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    I noticed.

    I can get it to work like I shown in my photo but like you said about driving the FET nuts. Seems like the power to them been cut in half with the flash rates skipping. Looking at my schematics to fix it and the thing u told me think about is driving me nuts but I'm sure I can figure it out.
     
  15. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    If I wasn't involved with my own hair pulling project I'd draw it for you. As I stated earlier it's difficult to discuss your circuit when it doesn't contain component Name/Number designations. It's a royal peta to have to describe a component as "The 555 located on the top left of your schematic.." when "U1" does the job without any ambiguity. Capice?

    Chris
     
  16. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    I think might just be more easy to turn this in to a Arduino project I been looking in to the idea of doing that.
     
  17. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    This is a simple Picaxe 08M2 project. Cheaper too!

    Chris
     
  18. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    Could I just use the arduino it self or do I really need the Picaxe 08M2 to program. I always had had time finding the chips to program for Arduino.
    I never messed around in this area before. But person I buy parts from told me I should try using a Arduino uno or a Arduino Nano. Seal it in a project box, and take usb/car charger apart and use that to get my 5volt power supply for it.
     
  19. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    No, Picaxe is totally different different than Arduinos. You can read all about Picaxe and the Picaxe system of programming at Picaxe.Com

    In your case a single 8 pin (DIP) 08M2 Picaxe chip will replace all three 555s! All Picaxe software is freeware. This includes the Editor/Programmer/Simulator IDE.

    I love Picaxe! :)

    Cheers,
    Chris
     
  20. CodyF11-13

    CodyF11-13

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    Sep 16, 2015
    Like I said in my very first post "Image below Is part of my circuit to give a idea what I'm trying to do" Reason I couldn't show it was all the LEDs being used, and the 555 timers that would power the high power LEDs. Since I'm able to do more and not stuck to 555 timers I added 1 more flash pattern. From look of it I need something that could be programmed to flash 5 sets of leds. I'm unsure of that 08m2 Picaxe chip would work. I only know few things about Arduino. The pinout of the 08m2 looks like it could handle 4 outs?

    I made a small animation of whats going on.
    Link to the Animated Pic
    http://gifcreator.me/viewgif/20151007-06-ANJTWCiJLK9pNwAP-eVQJTX

    Frist photo is Animated photo. The Second photo named LEDs.png shows amount of leds. Also what can be hooked together. Only thing not sure about is the 16x leds in parallel 3x in series. I might make it lower amount of LEDs being used there.

    Sorry if this all seems confusing I tried my best make it clear and clean
     

    Attached Files:

    Last edited: Oct 8, 2015
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