LED Chaser

Discussion in 'The Projects Forum' started by QuangVuong, Sep 2, 2011.

  1. QuangVuong

    Thread Starter New Member

    Apr 2, 2011
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    I know this topic had been discussed quite a few timesthroughout this great forum, but I dont think there has been one which is like mine.

    Well for the past few weeks Ive been trying to make a LED chaser circuit on a strip board, but Ive been having problems with it.

    This is the diagram Ive been folowing.
    [​IMG]

    Which comes from this site.
    http://www.electronicecircuits.com/electronic-circuits/4017-led-knight-rider-circuit-diagram

    Couple Qs on it too. There are a couple unlabelled pins on there. I believe pin 3 of 555 is connected to 12 of 4017. 8 and 16 are positive and negative. Could someone confirm which pins they are.

    Instead of 6 LEDs, Im only using three, so i stopped and reversed the sequence at pin 7(I think thats what Im supposed to do). So in theory it should flash left, middle, right, right, middle left, repeat...(flashes back and forth) Thats what I was aiming for, but it simply isnt working.

    Maybe someone could help me with a simple strip board design(most compacted using normal sized components) or a new circuit diagram to accommodate three 3mm red LEDs.

    Ill take some pics of what I have so far tomorrow arvo. Basically I have followed everything in the diagram, cept that I reduced it to 3 LEDs. Still only have the diodes soldered, since it isnt working. I believe that it may come from the 555. Output is not pulsing when measure with a multimeter.

    Thanks
     
  2. Wendy

    Moderator

    Mar 24, 2008
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  3. elec_mech

    Senior Member

    Nov 12, 2008
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    I haven't tested it, but give this a shot. The output of the 555 needs to go to the clock input of the 4017, pin 14, not pin 12. Pin 12 is an output.

    Look at the 4017 datasheet, specifically the timing diagram. What I've attempted here is to turn on D11 (LED#1) with output 0 first, then D12 (LED#2) with output 1, D13 (LED#3) with output 2, back to D12 (LED#2) with output 3, then tie output 4 to the reset pin which will cause output 0 to come back on and restart the sequence.

    A better visual:

    1. First clock pulse -> LED #1 ON
    2. Second clock pulse -> LED #1 OFF, LED #2 ON
    3. Third clock pulse -> LED #2 OFF, LED #3 ON
    4. Fourth clock pulse -> LED #3 OFF, LED #2 ON
    5. Fifth clock pulse -> LED #2 OFF, Reset goes high and LED #1 ON
    6. Sixth clock pulse & beyond -> steps 2 - 5 repeat

    Let us know if you run into any problems.
     
  4. QuangVuong

    Thread Starter New Member

    Apr 2, 2011
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    ^^
    Thanks for clearing that up. I moved the link to pin 14 instead of 12, and added in the link from negative to pin 13. But I dunno it still isnt working. Theres power going through LED 1(pin 3), but its just continuous. Measure out put of the 555 and its also continuous, not pulses.

    Anyway heres the circuit so far. Strips are going vertically in the pic as shown by black lines.
    [​IMG]

    Links are shown. Link from pin 2 to pin 6 does not connect to the link from positive to pin 4.

    Maybe a strip board circuit would be helpful if youve got the time. Thanks
     
  5. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
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    I need to examine your picture some more, but right off the bat:

    Try adjusting VR1 until you see a pulse out of pin 3 on the 555, say about 1 second on and 1 second off or more. If it is coming out of pin 3 so fast that it looks continuous, then it's going too fast to see on the 3 LEDs.

    As a backup, try disconnecting pin 3 of the 555 from pin 14 of the 4017. Then put a 1 to 10kΩ resistor from pin 14 to ground and a momentary switch to pin 14 too. Connect the other end of the switch to Vcc. Push the switch. Each time you push the switch, you should see a different LED light up. Now, we really should debounce the swtich, but this should be enough to make sure the 4017 is wired correctly. Then you'll know you just need to focus on the 555.
     
  6. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
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    Also check the following on the 555:

    1. Pin 4 should go straight to Vcc - it appears it is going between R1 and VR1.

    2. It looks like pin 7 is going straight to ground. It should go to between R1 and VR1.

    3. It also looks like pins 2 and 6 are going between R1 and VR1. They should go between VR1 and C1.

    4. I can't see the back of your board, but make sure the pin coming off VR1 (where VR1 and C1 are connected) is not making contact with ground.

    5. I'm sure you've done it, but just in case, verify the center pin of VR1 is connected to the VR1/R1 connection.

    6. I can't tell for sure, but verify pin 13 on the 4017 goes to ground and pin 16 goes to Vcc. I think I see a third connection (drawn?) between those points too, but I can't tell where it is going.

    7. Just to help eliminate any noise, add a 0.1uF capacitor between pin 16 of the 4017 and ground.
     
  7. QuangVuong

    Thread Starter New Member

    Apr 2, 2011
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    Well for the past week I've been trying the 4017 out with the momentary. It's a bit random though. Sometimes it's 2 LEDs on and other times it's 1 LED on.

    I really can't get it working. I'd be very grateful if you could make up a stripboard circuit diagram for me. Thanks
     
  8. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Also, looking at your potentiometer, it has a max resistance of 100K. Depending on the size of your cap (on pin 2), if you have the pot turned all the way up to 100K, it will be blinking VERY slowly. If you don't wait a while for the LED to change, it may not. Could you possibly post more photos of your board, at different angles?
    Good luck!
    Der Strom
     
  9. QuangVuong

    Thread Starter New Member

    Apr 2, 2011
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    Here they are. It may be a lil different to the previous circuit, and I had removed the 555. Just placed it back intere, so links may be wrong.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  10. Tealc

    Member

    Jun 30, 2011
    140
    10
    I think the back of the strip board is a very important factor when trying to fault find a circuit. You've posted some great images of the front of the board but the rear side could be completely wrong.

    So please post some images of the rear of the board.

    I built a circuit using two 4017s, 18 LEDs and a 555 timer recently and all the faults were on the rear of the stripboard where a tiny sliver of solder had crossed a track, or where a joint had risen off the board.

    A small application called 'Verodes' helped me construct my circuit on stripboard. I'd already proven the circuit to be working in Multisim so I just worked one wire junction at a time, adding links as I went. It worked first time (after removing the soldering faults) and I am no expert.

    I would recommend getting yourself some solderless breadboard to test out circuits. You can then easily move wires around and test circuits and everything is on display as there's no cutting of tracks to worry about. Circuits tend to take up a lot of room using a breadboard but at least you can see it working before you commit solder to it.

    Something like this little circuit using a 555 and just the single 4017.

    http://www.youtube.com/watch?v=Rm2cTHN9nEM
     
    Last edited: Sep 15, 2011
  11. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    It would also be a good idea to test your 555 to make sure it's working anyway. Usually if the output is constant, it means either something inside it is fried, or something is connected wrong to pin 2, 6, or 7.

    By the way, I thought the 4017 was only a decade counter--it would count 1, 2, 3, 4...10, and then straight back to 1 to start it over. It wouldn't give you the chaser pattern of 1 2 3 4...8 9 10 9 8...4 3 2 1.
     
  12. Tealc

    Member

    Jun 30, 2011
    140
    10
    I think that's already been dealt with as pins 3, 2, 4 and 7 have outputs while pin 10 goes to pin 15 for the reset.

    On the 4017 IC..

    It looks like Pin 12 and Pin 13 are joined. I've never done that. I usually have Pin 12 left blank and Pin 13 going to ground. Not quite sure what happens if it goes to ground but I've not seen it used much. In the Bill Marsden circuits and ones I've followed it's never connected. I've simulated it in Multisim and it seems to have no adverse effect.

    Pins 8 and 13 usually go to ground. I can see your 13 going to ground but not your 8 (unless you have a link on the underside of the board)

    Not much point commenting further on the 555 if you have removed and not verified the links.
     
  13. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Okay, I've had time to test the circuit and it works, although I left pin 5 unconnected. Your new pictures appear to have fewer connections than your first. As shown, it won't work unless you've got more connections on the back. Off the bat, pin 4 of the 555 needs to be tied to Vcc (6VDC).

    I've created a strip board wiring diagram with the circuit I tested on a breadboard. The potentiometer will give you a decent range of speeds. You can also just try a 560Ω resistor in its place which gave a decent blink rate, roughly 1 second I think.
     
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  14. JRJJ

    New Member

    Aug 16, 2012
    2
    2
    Hey guys, I know this is kinda late reply for a post but I came across the diagram in the beginning of this page when I wanted to create the knight rider circuit and wanted to clear this diagram problem hopefully for future hobbyist like me. Here is the same diagram with complete pin outs labeled and the circuit assembled on a breadboard. Its tested and working.
     
    QuangVuong and MMcLaren like this.
  15. JRJJ

    New Member

    Aug 16, 2012
    2
    2
    The circuit is attached to a 9v battery. Pin 12 is left unconnected it is used to connect to other IC's in series. It is also known as carry out pin.
     
  16. QuangVuong

    Thread Starter New Member

    Apr 2, 2011
    12
    0
    Wow that's great mate!

    Will have to try it out soon!
     
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