Led Chaser using CD4017

Discussion in 'The Projects Forum' started by uni85_99, Jun 16, 2006.

  1. uni85_99

    Thread Starter New Member

    Jun 16, 2006
    1
    0
    Im working on an led chaser circuit. I found it on many websites and chose the one which doesnt contain any 555 timer IC .. just a CMOS counter IC and a CMOS NAND gate to act as the oscillator.

    Now. The problem is that the circuit was constructed exactly as described on the site aaroncake.com but it doesnt work. It uses a 9V battery and I used a fresh one. All the components were new. The LEDs were checked by the shopkeeper himself.

    I dont know what might have gone wrong. Can anybody help me?

    Thanks

    Uni
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Before our members can help you with your circuit problem we will need a few basic details.

    1. the schematic diagram of your circuit.
    2. a description of the problem you are experiencing with the circuit that contains
    as much detail as you can supply.

    hgmjr
     
  3. Gadget

    Distinguished Member

    Jan 10, 2006
    613
    0
    OK, Im guessing its something like a CD4011 with 2 of the NAND gates hooked up to form an Oscillator(or possible a single gate of a 4093)... Then perhaps..(but not necessarily) using another gate as a buffer., then feeding the Clock in (pin 14) of the CD4017....

    If the LED on Pin 3 ("0" output from 4017) is lit, but nothing else, then there is a problem with the Oscillator circuit...not oscillating OR pin 15 and pin 13 of the 4017 have not been pulled down to the negative volts rail.
    (nb, if less than 10 LEDs have been used, then pin 15 (4017) may be connected to an output pin on the 4017 to reduce the count)
    If ALL the LED's are lit, then the oscillator is running too fast. Check the external components around the 4011 (4093).
    If NONE of the LEDs are lit, then check all the chips are in the right way around. Check you have 9 volts on pin 14 of the 4011 and pin 16 of the 4017, and 0 volts on pin 7 of the 4011 and pin 8 of the 4017.
    Also check all the LEDs are in the right way around as well.

    CMOS chips arn't as bad as they used to be, but they can still be damaged by hooking up wrong, or stroking the cat, or walking over carpet as you hold the chips or assemble the circuit. To be sure, wear an Antistatic wrist band. If the chips are shot, then don't dispear, they are cheap to replace, and if you have used IC sockets, simple to replace as well.
     
  4. pebe

    AAC Fanatic!

    Oct 11, 2004
    628
    3
    Is this the circuit you are using?

    http://www.aaroncake.net/circuits/chaser.htm

    If so, make sure pins 8,9,12 and 13 of the 4011 are connected to ground or +9v, and pin 12 of the 4017 is not connected to anything.

    You should be using a buffered 4017 (suffix 'B' ) when driving LEDs direct. Even then, I think you woud be pushing your luck to try the 220 ohms mentioned for R3. The outputs of the 4017 were not designed for that much current.
     
  5. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    At the risk of stating the obvious, make certain that you have installed the LEDs in the correct polarity.

    If your LEDs are in the typical T-1 3/4 package you can usually identify the cathode lead (negative) as the one closest to a flat portion of the rim of the package.

    Here a link to an example datasheet that shows the mechanical details for the T-1 3/4 package.

    datasheet for T-1 3/4 packaged LED

    hgmjr
     
Loading...