LED Chaser

Discussion in 'The Projects Forum' started by linwiz, Sep 25, 2013.

  1. linwiz

    Thread Starter New Member

    Dec 7, 2011
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    MODERATOR EDIT: This was split from here: http://forum.allaboutcircuits.com/showthread.php?t=81140

    Thank you for this post! I think that this may be exactly what I am looking for.. Light up all LED's one by one and leave them on, once all are on... reset, right?

    I have never dealt with decade counters before, I have a PICkit2 programmer, But have failed to figure out any information on programming a CD4017B, so I am not sure what I am supposed to do with the asc file.

    I would like to try and have this circuit completed by December, for my wife's graduation. I would like to verify the parts list with someone, if anyone would be so kind.

    100 leds
    20 2N3904 transistors
    2 CD4017B decade counters
    10 1k ohm resistors
    1 300 ohm resistor
    1 220k ohm resistor
    1 200k ohm resistor
    2 100n capacitor
    3 CD4093B NAND GATE "Schmitt trigger quad NAND package"?

    I would truely appreciate any help at all.
    Happy wife, happy life right?
     
    Last edited by a moderator: Sep 26, 2013
  2. Art

    Distinguished Member

    Sep 10, 2007
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    Not sure if it really helps you at all, it's just funny that I took this photo not so long ago:

    [​IMG]

    This one is controlled with the variable resistor.

     
  3. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    A CD4017 does not require programming; it is controlled by the other components connected to it.

    You only need one one CD4093. Otherwise, I think your parts list is accurate.

    And, from what I can tell, it lights one LED at a time, i.e., each LED lights and goes out, then the next one lights and goes out. Is that what you want?
     
    Last edited: Sep 26, 2013
  4. linwiz

    Thread Starter New Member

    Dec 7, 2011
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    A variable resistor for speed I assume? That could prove very useful. If no programming is required, what was the code developed and posted for? For the way i need this to work, the LEDs would need to stay lit, and not go out. I have seen decade counters do this but they didn't provide anywhere near 100 led count.
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Wild thought: Stack LM3914N's in bar mode & use a sawtooth input. Unknown as how many can be stacked, National says " two or more".
    Big bar graph with 7017 gets complicated, as illustrated in sketch. Need 10 of these. Each LED needs a current limiting R as current for collum varies from 20 mA to 200 mA & now needs a driver able to handle 200 mA. At 0 collector V, wonder if there would be some LED glow? May be using a FET, BS 170 ?, would solve this?? Or add a bunch of AND gates & second 4017 each output in turn would look into 10 logic inputs?
    At least it is something to throw stones at.
     
  6. tracecom

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    The .asc file is an LTspice file of the schematic; at least, I think that is what it is. I don't use LTspice, so I am not postive, but I am positive that a 4017 is not programmable with a PICkit2; it is for Microchip microcontrollers.

    Bernard's idea should work for LEDs to stay lit.
     
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    A CD4017 has ten outputs, but only one is 'on' at a time. Hence some latching arrangement is necessary if you want LEDs to come on in sequence and stay on until a master reset turns them all off simultaneously. The CD4017 won't cut the mustard.
    Another problem is going to be heat dissipation: if one IC is driving several LEDs, even at a few mA per LED, the power soon adds up and the IC could be overloaded. Logic/counter ICs may need additional output buffers (e.g. transistor stages) to drive the LEDs.
    I can confirm that.
     
  8. linwiz

    Thread Starter New Member

    Dec 7, 2011
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    In not exactly sure if I could just wing it in an attempt to follow Bernard's response. My circuitry skills are at or below hobbyist, which is what was so tempting about the OP schematic. I may be overthinking this, but in not sure. The end goal is a "heartbeat monitor"/EKG/ECG simulation. This seems like the best route but maybe there are other options I have overlooked.
     
  9. Bernard

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    Not really complicated, just a lot of repitition. I would add the NANDs or AND's [ 74ACT08, enough output to drive LED's ]. 25 each OR & AND, & no transistors. Out of time now, but can make another partial sketch if desired.
     
  10. linwiz

    Thread Starter New Member

    Dec 7, 2011
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    I am sorry, I am trying to understand but I really only have a little knowledge on transistors and AND/NAND. Enough to follow a schematic. I will try to do some figuring once I get home this evening, but would appreciate anything your willing to take the time to help me with.
     
  11. Bernard

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    Sorry, I screwer up again, post 5 will not work. One collum will stay on, but when 4017 resets each preceding collum is wiped out.
    As Alec_t said , we need a latch, something like a low power SCR, 2N 5060 etc. then each junction would need a AND gate driving a SCR driving LED, + some resistors.
    How are the LEDs to be arranged? How bright? Any chance for just 80 LEDs, would only need just 2 AND IC's for each collum.
     
  12. Bernard

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    Shift registers might be a better way. 13 CD74AC164E @ about $.56 [ Mouser ] have enough drive so only a resistor & LED is needed for each output with one IC for clock and reset inverter. "1's are loaded at serial input & are shifted untill 101 th stage is reached. When 101 goes high it is inverted to put a low on clear, & everything starts over.
    Probably should be reviewed, too many senior moments lately.
     
  13. Bernard

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    This is what I had in mind. I do not have any IC's to try it with, but should be good for 20 mA on each output?
     
  14. linwiz

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    Dec 7, 2011
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    this is turning out to be a expensive project, but I should have expected as much.
     
  15. Bernard

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    Something like $ 35?
    What color LEDs? What pattern are LEDs in?
     
  16. Bernard

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    If I were putting this togetrer, ' think it would be " dead bug style", as used on other of my shift reg. proj. I used double sided foam tape to mount ICs upside down. Bend pins 1,2, &14 inward, connecting to VCC buss. If available, 1/10 in, self stick copper foil makes nice buss bars; by name of "circuit-stik", or cut down tape fron stained glass supply. If LEDs are in a pattern, ckts groups of 8,

    can be placed near LEDs to keep leads short.
    On sketch , think pins 14 were labled 16??
    2 nd choice would be " stripboard" which I have verry litle exp. with.
    Did not have a SR but connected a 74ACT14 with all 6 outputs driving bright red LEDs continusly @ 17 mA, 5V supply for last three days, no problems, verry low heat.
     
    Last edited: Sep 30, 2013
  17. linwiz

    Thread Starter New Member

    Dec 7, 2011
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    I have 100 blue LEDs I am going to salvage from a cheap Ac light set from eBay. They will essentially be in a strip, just not a straight line. What would you guess it would take to run this on battery for approximately 3 hours?
     
  18. Bernard

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    4, Ni mh C cells, 5 Ah, about $ 4 = $ 16
    1, Li Fe PO4, 6 V, 5 Ah, $ 45.
    Sealed lead acid, 6 V, 5.5 Ah, $ 11.69-- first choice

    For non rechargeable maybe 3 or 4 C or D Alk. & may need a regulator??
     
    Last edited: Oct 1, 2013
  19. Bernard

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    Think I would skip C alk, V drop @ 2 A prettysteep. Average current about 1 A. 5 red & one bright blue LED are still going bright, driven by 74ACT14.
    Shown is first & last stage with pin #s. Clock period is determined by Rx & Cx @ about P = .7 RC
     
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