I want to make a led blink

Discussion in 'The Projects Forum' started by jhawk100, Jun 2, 2013.

  1. jhawk100

    Thread Starter New Member

    Jun 2, 2013
  2. LDC3

    Active Member

    Apr 27, 2013
    Actually, we could make it even easier for you. If you can tell us the type of connection your headset has to your phone, we could detect when your headset is 'on' and light the LED.
  3. jhawk100

    Thread Starter New Member

    Jun 2, 2013
  4. jhawk100

    Thread Starter New Member

    Jun 2, 2013
  5. LDC3

    Active Member

    Apr 27, 2013
    I was thinking that this might work.
    I didn't find a symbol for a stereo plug, but it needs to be placed on the right where the 3 wires are.
  6. jhawk100

    Thread Starter New Member

    Jun 2, 2013
    sorry I have no idea what that means
  7. LDC3

    Active Member

    Apr 27, 2013
    Sorry I made a mistake. If resistors are used, then you will get cross talk between the microphone and the speaker. The connection to the jack may need to be changed as well.

    Does anyone see any problems with this?
  8. wayneh


    Sep 9, 2010
    If you want to stick with the manual switch, the circuit you need is very simple, with 4 components in series:
    1. Battery
    2. Switch
    3. LED (or 2-3 in in series)
    4. Resistor to limit current

    That's more-or-less what was in your picture but the resistor was not shown, probably because that LED strip had them built in. The choice of LED(s) determines the choice of the resistor(s). A typical LED may be rated to 20mA. It'll be plenty bright at half that, or 5-10mA. With 9V, you can put two LEDs in series with one resistor. Each LED will drop ~3.5V, so you probably cannot use 3 or they may not light once the battery ages.

    If 2 LEDs are not enough, you can add more parallel strings of two-LEDs-plus-resistor, as many as you like. A typical 9V battery might handle 5 strings pretty well if they are all less than 10mA.
  9. paulktreg

    Distinguished Member

    Jun 2, 2008
    The LED you've pointed to on ebay looks to have a built in resistor and will work with a 3.6V to 12V supply so keep things simple and forget the detecting bit!

    All you need is the battery, switch and LED in series, forget the fuse.

    9V Battery+ > switch > LED+(Red) > LED-(Black) > Battery-.
  10. absf

    Senior Member

    Dec 29, 2010
    The LED that you bought has a chip built-in that flashes the LED. It can accept 3.6 - 12V dc so no resistor is needed in series. The operating forward current is 30mA, so your wiring should be okay.

    But I think you should remove the black wire to the switch and just leave that tag NC (no connection). Your switch is probably a SPDT switch with common at the centre. If that's the case, your battery positive would be shorted to the negative when it is in OFF position.

  11. dthx


    May 2, 2013
    Have you bought anything yet?
    If you have...or have not...let us know...
    It may seem complicated but what you want to do is simple.
    If you use a 9volt battery like your pic....you will need some way to attach a wire to the battery....cause the battery has no wires attached to it...(obviously)
    They sell a simple battery connector that clips to the battery and has wires attached to it. (Radio Shack)
    Then, just like PaulKTreg says (above)....
    Just connect everything in "a Line"...what these guys call " in series".
    Another words connect a wire from the battery ....to the switch.....to the led....and back to the battery....
    The wires can be of various lengths...
    You can twist the wires together and use a "wire nut" for the connection...
    Find a Radio Shack and see if the person in there can help you.....Occasionally they have someone behnd the counter that tinkers with electronics.
    Unless the LED that you buy has a "built in resistor" you wil burn it up.
    The one you showed us in the picture on EBay had a little bulge in one of the wires...that is were the resistor is located....they already put it in the wire...
    So if you get that one...or one like it...you dont need to worry about a resistor.
    If Ive made a mistake in any of my advice...someone will correct me.
    Hope that helps.
  12. edwardholmes91


    Feb 25, 2013
    I would use a flashing 14V LED a switch and a PP3 9V battery. This way you don't need a current limiting resistor and the circuit is literally three components wired in series.