Electronic Circuits and Projects Forum



multiple flashing LED not playing nice

123 Last »
  1. 9th February 2012 01:48 AM #1
    wilykat wilykat is offline

    multiple flashing LED not playing nice

    I wanted to wire up a bunch of cheap multiple flashing LEDs (red-yellow-off, 3 seconds total cycle time) that I got off eBay but they aren't playing nice. If I run just 1 LED they work fine but if I put 2 or more in parallel (each with its own resistor), they start misbehaving and flashing only red (for about 1/10th of a second) then off. it did not matter if I used resistor on anode or cathode side. I am just guessing but these flashing LEDs seems noisy and causing interference? It'd seem silly (and messy) if I have to add 100 capacitors parallel to each LEDs just to cancel out each other's interference.

    Is there a way to wire up some 100 of these as I wanted to put it inside my computer and make it look like that old computer with lots of flashing lights from old sci-fi show. (More specifically I wanted the WOPR display LED from the movie War Games)

    Available rail are 12v and 5v. As a last resort, I could also use 2 resistors one on each side of LED with a cap parallel across LED.
  2. 9th February 2012 01:53 AM #2
    ronsimpson ronsimpson is offline
    Do you have a data sheet or part number for the flashing LEDs?
    0
  3. 9th February 2012 02:38 AM #3
    wilykat wilykat is offline
    There is no datasheet with details, just some basic information:
    Code :
    Size (mm) 5mm
Lens Colour Water Clear
Forward Voltage (V) < = 3.6
Reverse Current (uA) < = 30
Luminous Intensity Typ Iv (mcd) 6000 - 7000
Life Rating 100,000 Hours
Viewing Angle 20 Degree
Absolute Maximum Ratings ( Ta = 25°C )
Max Power Dissipation PM = 80 mw
Max Continuous Forward Current IFM = 30 mA
Max Peak Forward Current IFP =75 mA
Reverse Voltage 5 ~ 6 V
Lead Soldering Temperature 240 ° C ( < 5 Sec )
Operating Temperature Range - 25 ° C ~ + 85 ° C
Preservative Temperature Range - 30 ° C ~ + 100 ° C

    I've contacted the seller to see if he can provide more.
    0
  4. 9th February 2012 03:13 AM #4
    ronsimpson ronsimpson is offline
    I am looking for how they think it should be powered.
    The LED is not just a LED it includes a IC inside.
    I have used a multi-colored LED blinker that goes through 32 colors. It will take hours to find the data sheet. We are using it in production. I have not thought about it in 2 years. I think it can not be used like you are using it. It sounds like the IC is being reset after its first step.

    Your part likely is not what I am using. But sounds like a line of similar parts. I will try to find more information. And you will try to get information.
    0
  5. 9th February 2012 03:19 AM #5
    ronsimpson ronsimpson is offline
    Is this what you have?
    Attached Files
    0
  6. 9th February 2012 07:38 AM #6
    wilykat wilykat is offline
    It is probably similar but I can't tell without opening the LED and putting it under microscope to see and it's pretty dang hard to open up a LED.

    Still, would a capacitor help? I have some SMD caps (0.01uF) and solder it between the legs of the LED.
    0
  7. 9th February 2012 10:48 AM #7
    4pyros 4pyros is offline
    Still, would a capacitor help? I have some SMD caps (0.01uF) and solder it between the legs of the LED.
    Cant hurt to try.
    0
  8. 9th February 2012 02:31 PM #8
    alec_t alec_t is offline
    You could also try putting a respective ordinary silicon diode (forward biased) in series with the dropper resistor of each LED. So you have +V /\/\/\/ >¦- LED. That should isolate each LED from its neighbours.
    0
    My circuit designs should be regarded as experimental. Although they work in simulation, their component values may need altering or additional components may occasionally be necessary when the circuit is built. Due safety precautions should be taken with any circuit involving mains voltage or electrostatic-sensitive components.
    Alec's First Law:-
    Every problem has a solution (given the right information and resources).
  9. 9th February 2012 02:36 PM #9
    ronsimpson ronsimpson is offline
    Try the capacitor across the LED. The ones I use draw very different current depending on where in the cycle they are.
    0
  10. 9th February 2012 02:54 PM #10
    audioguru audioguru is offline
    The power supply is not described. It must have a steady output voltage to power flashing LEDs so that they don't cause the voltage to bounce up and down and affect each other. Is the power supply a weak little battery?

    Try adding a 100uF or 1000uF capacitor parallel with the power terminals near the LEDs and resistors. 0.01uf will be useless.

    I hope the LEDs with their series resistors are really in parallel and not actually a few flashing LEDs in series.
    0
    Uncle $crooge
123 Last »
Tags
« help with a supposed simple circuit | What is the output voltage in this circuit? »
Similar Threads
Thread Starter Forum Replies Last Post
pic 12c508 flashing led billyboy Microcontrollers 11 7th March 2008, 11:05 AM
Flashing LED in a drumstick? grrr_arrghh General Electronics Chat 26 26th May 2004, 11:55 AM
flashing LED 1997 GA16DE General Electronics Chat 11 29th February 2004, 05:52 PM
PIC output signal not a nice square wave ChrisBennet Microcontrollers 4 26th February 2004, 11:51 PM
Flashing LED project johnk General Electronics Chat 10 21st May 2003, 02:29 AM
Electronic Circuits  |  Learning Electronics

Join our community with over 100,000 Members! It's free, easy and when you're logged in you have many more features! Click to register.
Page Time: 0.04498 seconds      Memory: 7,327 KB      Queries: 17      Templates: 0