A learning project

Discussion in 'The Projects Forum' started by Printz, Oct 3, 2010.

  1. Printz

    Thread Starter Member

    Oct 2, 2010
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    Well I tried this once before and because I didn't read the rules thoroughly it got closed. So let me try this again. I want to build a circuit that does this http://www.youtube.com/watch?v=eqId7g7SC10&feature=related but when one lights up it stays lit. There are other functions I want to add later too, but lets see if I can handle this first.
     
  2. marshallf3

    Well-Known Member

    Jul 26, 2010
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  3. Printz

    Thread Starter Member

    Oct 2, 2010
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    Could I use 2 of them in sequence to run 8 rows of 4 LED's? This might work fine, the input voltage is already pulsed.
     
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
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    If I recall they actually come with 10 outputs insequence but I don't think they have very high output capabilities at all thus requiring driver transistors for each output leg.
     
  5. Printz

    Thread Starter Member

    Oct 2, 2010
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    Each output won't have to drive but 4 LED's. Still to much?
     
  6. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    The "absolute maximum" sinking output (Iol) is 16mA
    http://webpages.ull.es/users/fexposit/7490.pdf
    You could place 2 LEDs (Vf=1.7v) and a 127Ω resistor in series, and two of these in parallel for each output, for 4 LEDs per output. But, that doesn't solve the light-and-stay-on condition that you want. I'd use a 555 driving a CD4017 Johnson counter, followed by an OR'ing diode matrix, followed by 4 NPN common-emitter LED drivers. This will give you lots of options for different sequences.

    Ken
     
    Last edited: Oct 4, 2010
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  7. John P

    AAC Fanatic!

    Oct 14, 2008
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    A 74190 wouldn't do what the video shows, and in fact the notes attached to the video explain that the output element is a 74138 demultiplexer. With that, you can get 8 light clusters even though only 4 are shown.

    If you use a 74HC138, the maximum output current per pin would be 25mA, though going that high wouldn't be wise. With 4 lights per cluster, you could still get them pretty bright if they're the high-efficiency type.
     
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  8. Printz

    Thread Starter Member

    Oct 2, 2010
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    The 555 and 4017 were the way I was leaning to begin with. I wasn't sure it would hold the rows on in sequence.
    I'm trying to control 8 rows of 4 lights, to make two sides. Turning on from the inside to the outside, like blinkers. If I'm going to be programming something, why don't I go ahead and add another function to the array. I just figured wire it differently to do this one but maybe it might be easier to digitize it. I'm trying to get the 2 array's to operate as one to create brake and running light on my bike.... that has a 2 stroke bolted to the frame.

    I hope I'm not breaking the no automotive rule, I didn't mean to before so if this still falls under that I'm sorry. It's not required to be plated or registered and I just want to be seen better at night. Thanks again everyone.
     
  9. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    "I'm trying to control 8 rows of 4 lights, to make two sides." With the 4017 just parallel each set of 4-LEDs-and-1-resistor with another set of 4-LEDs-and-1-resistor. One set of each pair will be on the right, the other on the left. You may have to change the 10K resistors to a lower value (4.7K ?) to drive the extra collector current in each transistor.

    Is the chaser version the running light or the brake light? Is the other mode to be just steady, no flashing?

    Ken
     
  10. Wendy

    Moderator

    Mar 24, 2008
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  11. beenthere

    Retired Moderator

    Apr 20, 2004
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    We will let this one go, as the intent is to enhance safety. The OP should use care in construction and mounting, not to mention weatherproofing all connection.
     
  12. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I've seen those little weedeater engines that can be clamped to a bike frame and run against the wheel, you can often pedal faster. :)
     
  13. Printz

    Thread Starter Member

    Oct 2, 2010
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    The steady will be the running light, which gets brighter for the brake. The chaser is the blinker. I had a little doubt that I'd be able to pull this off. My electronics background is only repairing radar units as old as me.
    I plan on putting the electronics in a sealed box, heat shrinking the wires so it looks clean too. As a future Mechanical Engineer, that's what I'm studying in school, I will make sure to be careful. Thanks.

    Mitchell
     
  14. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    So the chaser is the left/right turn-signal?

    Ken
     
  15. Printz

    Thread Starter Member

    Oct 2, 2010
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    Correct sir. I'll try and draw a picture if it will help, but knowing my art it won't do any good.
     
  16. tom66

    Senior Member

    May 9, 2009
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    I think turn signals are not allowed to be sequential in some places.

    Wikipedia (http://en.wikipedia.org/wiki/Turn_signal#Turn_signals):


    However, as it says the Mustang has them so maybe there are some exceptions.
     
  17. Printz

    Thread Starter Member

    Oct 2, 2010
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    Not to sound like a smart-a$$ but this thing already is a rolling gray area, so adding the signals is the last of my worries. I'm just super excited to have a brake light and BRIGHT tail light. Let me do some searching on the laws and see if we can make the running light pulse slightly for better night visibility. I'll make sure about the turn signal laws too.
     
    Last edited: Oct 6, 2010
  18. wayneh

    Expert

    Sep 9, 2010
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    Well put! Scooters are definitely on the fringe, and in some places this actually favors the scooter rider since the police would rather look the other way than try to figure out which laws are being broken or not. Behave yourself and they'll leave you alone.
     
  19. Printz

    Thread Starter Member

    Oct 2, 2010
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    It's worked for me so far, they leave the bike alone. Once I get this figured out on the bike I'm going to make another more polished version and try it on my 50cc scooter which they really hate, since it doesn't have or need plates and it'll still do 50mph. Safety is the name of the game right now though. Thanks again guys!
     
    Last edited: Oct 6, 2010
  20. marshallf3

    Well-Known Member

    Jul 26, 2010
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    So are the classic Ford Thunderbirds and a few other cars.

    It's all about they don't want people to think you're driving a police car.
     
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