Flashing LED

Discussion in 'Circuits' started by Admin, Apr 17, 2013.

  1. Admin

    Admin Administrator Staff Member

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  2. RB_H17

    RB_H17 New Member

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    I found using a 1microfarad capacitor that the LED remained ON. When I changed to a larger capacitor it then flashed. I am not sure why this is. I have used the same resistor values as yourself and changed the chip twice.

    Thanks
    Admin likes this.
  3. Admin

    Admin Administrator Staff Member

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    Thats a strange one.

    I wonder if the 1uF capacitor was blown. If it was it would have created a break in the connection and made the LED appear to stay on. You can see this happening by removing the capacitor when the circuit is running - the led will stay on.

    Regards,
    Admin
  4. Admin

    Admin Administrator Staff Member

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    Breadboard Layout:

    Flashing-LED.png
  5. Andrew

    Andrew New Member

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    I need to make this circument's PCB for the University! Can someone help me finding the capacitor's datasheet (for the dimensions) please?
  6. Justin

    Justin Member

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    Data sheets depend on what model the capacitor is. The average capacitor is 1/3rd of an inch apart from the leads, I used these dimensions for my "Dummy Alarm Circuit" circuit board construction and it worked just fine.
  7. Eric

    Eric New Member

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    My hobby is model railroading and I like to build my own circuits. My track power runs off of AC, there are decodes in the engines that convert the power to DC to make them run. I'd like to use this flasher for in the last car of the train for the flashing light on the rear. I built this circuit on a breadboard and it works fine from a 9v battery. When I try to power from track power the LED stays on and doesn't flash. I used a bridge rectifier to conver AC to DC. I'm then using a LM317T from RadioShack. I wired that according to the directions on the package. I checked the in and out voltage. In is 18v out is 9v. What am I missing or not getting to get the LED to flash from track power?
  8. brujahrage

    brujahrage New Member

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    I ran into the same issue as well. I fixed it by swapping out for a 1 uF cap that's not electrolytic, I had a bunch of these left over from a couple of semesters back:

    http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_null_1841127_-1
  9. Justin

    Justin Member

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    So I'm going to be making this circuit next. I'm back in electronic technology class so I get to make more of these :D Instead of just doing 1 circuit this year I'm hoping to do three. This one, one my teacher gave me (This one is Surface Mount Technology so I might start working with those soon), and another one from this site. I'm not sure which one I should do next? Any recommendations? Nothing too hard :eek: I'll post my CAD drawing of this circuit tomorrow when I'm back in that classroom. It's already finished and all I need to do is design the next circuit so we can make all three of them at once to save time and not have to go through it all over again ;)
  10. George

    George Moderator

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    What are you using to build the surface mount circuits on? Are you just getting a surface mount prototype PCB or design and have your own made? If you go with the prototype board there are plenty on eBay for sale of all different sizes and layouts and pretty inexpensive.
  11. Justin

    Justin Member

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    We're making our own. We're going to mill a copper PCB board and have it draw in the paths. We also are going to do the chemical process (Forget what it's called) where shine a light over the circuit with a printed outline to prevent that part from washing away, dump in it some chemicals (warm and moving) to wash away the unwanted copper, then just rinsing it off, drilling the holes (Not for the SMT circuit), and soldering the parts on. We're not going to be buying other boards online because it's part of the module to make one.

    like this, but we're using slightly different tools
  12. Daithi

    Daithi Member

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  13. Daithi

    Daithi Member

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    Ran into this as well... I ended up swapping the 1uf with a 100uf (worked fine)... Then I wanted to power it with a 4.5 volt remote control so I swapped out the 470k resistor with a 10k resistor and added a second LED... This circuit will eventually end up as navigational blinkers in a starship model... Here's a video of the breadboard layout:

  14. Justin

    Justin Member

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    Thanks for the information, but my teacher and I already know what we're going to be doing. I'm sure those links will help others out though! It may even help me out in the future when I want to make another board but I don't have the school's equipment.
  15. George

    George Moderator

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    You need to tell your school that if they expect you to build a surface mount board they need to get you one of these. :eek:

  16. Justin

    Justin Member

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    :eek:

    We don't need that as there are only like 10 components that are going on the board. I've placed them far enough apart to be able to place them with my fingers and still have the ability to solder. I wish I had one of those though:eek: But it's not like we're making super uber hard circuits :D
  17. Daithi

    Daithi Member

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    Sweet... But I'm thinking a bit overkill for what Justin needs... :p
    Now if they ever come out with one of those that makes grilled cheese sandwiches, grills a perfect steak, press and fold my clothes all while building surface mounted boards I might get one... :D
  18. Sudheerelktronics

    Sudheerelktronics New Member

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    Hi! I have seen another circuit for LED flashing lights. If anybody interested to try this, visit LED Blinking Circuits. It includes 2 circuits - one is for Bicolor LED dancing lights, the other one is for LED flasher circuit.
  19. Mr. Batraaf

    Mr. Batraaf New Member

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    Thanks for this. Works great!
    Lowering R2 and hooking up a little speaker instead of the led produced my first working audio oscillator.
    Great fun!
  20. scuboo

    scuboo New Member

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    Hi Guys
    What is the recommended capacitor for this circuit?
    I want to use it to simulate an arc welder in an engine shed on a model layout.
    Thanks