Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

555 Timer Madness (Help)

  1. Apr 3, 2016 #1
    Hello, I have been in the process of building a small lightning cloud out of Poly-Fil and some LED's. I have looked up on how to build flashing LED's with a 555 timer, and I have tried (many) times, yet every time I hook up the 9v battery, my LED either turns on, but does not flash, or doesn't come on at all until I turn my 10K pot all the way down. I have checked for loose connections, grounding issues, I cannot find any. I have triple and quad checked the diagram. I would really like to be able to use 2-3 lights that fade on and off somewhat quickly, but softly, as to look like lighting. I had bought a 4017 decade timer, in hopes of scattering the lights a little, but first I need to get this 555 to work.

    I'm using a 9v battery (I would like to make it a 12v wall wart, if possible)
    200uF cap
    2n2222 transistor
    1K Ohm resistor
    400 Ohm for LED (calls for 370, but all I have)
    10K Ohm pot to slow the rate of flashing.
    (All components are Texas Instruments brand)

    PS. I'm not using a breadboard of any kind. I'm (sadly) only able to solder this all together with wires without any kind of good mounting for it. I also bought a 1uf cap for pin 5 but I (stupidly) realized most diagrams call for .1 or even .01.


    Any kind of help would be immensely helpful!! and I appreciate any input!


    The circuit I'm trying to make. http://www.instructables.com/id/Pulse-Generator-Using-a-555-Timer/?ALLSTEPS
     
    Last edited: Apr 3, 2016
  2. jcsd
  3. Apr 3, 2016 #2
    Link to diagram for your circuit?
     
  4. Apr 3, 2016 #3
    You have not included enough information to trouble shoot the problem. Do you have a link to the circuit you are trying to build? If so please post it.
     
  5. Apr 3, 2016 #4

    davenn

    User Avatar
    Science Advisor
    Gold Member


    Hi there
    welcome to PF :smile:

    none of your info tells us anything about how you wired it up ... chances are your problems are layout/wiring related

    firstly, show us your circuit diagram you used
    secondly show us some sharp and clear pix of your construction .... clear enough that we can read the text on the components


    Dave
     
  6. Apr 3, 2016 #5
    Yes! been trying to edit it in for a few. sorry about that.
     
  7. Apr 3, 2016 #6
    Ok, This is a standard 555 astable oscillator The resistors and cap you are using will cause the LED to flash around 10Hz. This will appear as a fast flicker. This seems a little fast for the effect you seek. First question what strobe rate do you want?
     
  8. Apr 3, 2016 #7
    Keep in mind, I understand that this is a VERY crude looking circuit I have made and this is not how it should be done (With a piece of sheet plastic) But this is all I have at the moment. But that's beside the point of why I'm not understanding why it is not working.

    http://imgur.com/lqRLa29 [Broken] http://imgur.com/lqRLa29 [Broken]

    http://imgur.com/EGY3io2 [Broken] http://imgur.com/EGY3io2 [Broken]

    http://imgur.com/AEpWU4j [Broken] http://imgur.com/AEpWU4j [Broken]
     
    Last edited by a moderator: May 7, 2017
  9. Apr 3, 2016 #8
    The 555 timer is very tough. I have put together circuits that worked with clip leads. I expect that The LED is flashing just fine, but too fast. What flash rate do you want. Right now, with a 1uf cap and 100kohm resistor the flash rate is 10 times a second.
     
  10. Apr 3, 2016 #9
    I was hoping for a 1-2 second delay between each flash, if possible. I was going to start with the cap and resistor I have and change them to my liking once I had it working. I have two semi-new PSU's that have anywhere from 100-3.5k uf caps in them (don't know if I can use them though?) I can get resistors as needed from my local electronics shop.

    And thank you, sir/ma'am for your help.
     
  11. Apr 3, 2016 #10
    Your 100kohm resistor is way too small. If the cap stays the same then the resistor needs to be something larger than 1 meg ohm. At that resistance you may start to have current leakage problems. Try the larger resistor. But a better solution is to increase the cap to 10uf.
     
  12. Apr 3, 2016 #11
    Yeah, use the bigger cap, and then use a variable resistor in line with your fixed resistor.
    See what works.
     
  13. Apr 3, 2016 #12
    You may want to get the circuit working with fixed resistors first. Try using fixed resistors instead of the pot until the circuit works. once it is flashing then you can play with variable resistors to adjust the flash rate.
     
  14. Apr 3, 2016 #13
  15. Apr 3, 2016 #14
    Okay, I replaced the cap with a 10uf and also replaced the pot with 100k fixed. Although I had noticed that when I had disconnected the battery earlier, the LED stopped coming on at all. Nothing had come loose and/or short circuited that I know of. 555 timer was cool, LED is fine (tested it)


    Gahh I wish I had a breadboard right now...haha.
     
  16. Apr 3, 2016 #15
    Well I looked over the wiring. It is not easy with the black plastic in the way. But I can sort of trace the connections. It looks fine at first glance. This is a standard circuit straight from the manufacturers spec sheet of recommended circuits.
     
  17. Apr 3, 2016 #16
    This is my last post. It is after 11 pm here.
     
  18. Apr 4, 2016 #17
    I have done the same a dozen times, on half dozen different diagrams. Obviously the way I'm building these are wrong. The way I'm seeing the diagram or something. I'm going to be able to get a breadboard today, so I'm just going to get it to work on one of those and work from there.

    I really appreciate your time trying to help me.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: 555 Timer Madness (Help)
  1. 555 Timer Help (Replies: 5)

  2. Help 555 timer problem (Replies: 3)

  3. 555 Timer Chip help (Replies: 8)

Loading...