madbeanpedals::forum

Projects => General Questions => Topic started by: Roctopus on July 08, 2011, 06:25:17 PM

Title: Multiple LED's
Post by: Roctopus on July 08, 2011, 06:25:17 PM
I'm working on an idea that would require me to have three external LED's. However most builds only have one LED. Is there a way to wire more than one LED to a build? If so, how would you do it?

Thanks!
Title: Re: Multiple LED's
Post by: gtr2 on July 08, 2011, 06:46:30 PM
Can you clarify how you plan to run the leds.  In series on one switch?
Title: Re: Multiple LED's
Post by: Roctopus on July 08, 2011, 06:50:29 PM
Quote from: gtr2 on July 08, 2011, 06:46:30 PM
Can you clarify how you plan to run the leds.  In series on one switch?

Yes. I want to put them in clear shaft pots and illuminate three clear knobs at the same time.
Title: Re: Multiple LED's
Post by: k.rock! on July 08, 2011, 08:19:59 PM
I would think running them in parallel might be best... like this:

           ----|>|----
          |              |
+9V---- ---|>|---- -------ground
          |              |
           ----|>|----


This will supply even voltages to all three of them :)


-Kaleb
Title: Re: Multiple LED's
Post by: oldhousescott on July 08, 2011, 08:39:18 PM
Sorry Kaleb, but no. Whichever LED has the lowest forward voltage drop (even with LEDs of the same type) will get all the current. Put them in series, nose-to-tail. Figure a total voltage drop of about 6v for the three LEDs and calculate your dropping resistor from that.

You could put individual dropping resistors for each LED, but that would mean two more parts and extra wasted energy in the form of heat from the resistors.
Title: Re: Multiple LED's
Post by: k.rock! on July 08, 2011, 09:02:45 PM
Quote from: oldhousescott on July 08, 2011, 08:39:18 PM
Sorry Kaleb, but no. Whichever LED has the lowest forward voltage drop (even with LEDs of the same type) will get all the current. Put them in series, nose-to-tail. Figure a total voltage drop of about 6v for the three LEDs and calculate your dropping resistor from that.

You could put individual dropping resistors for each LED, but that would mean two more parts and extra wasted energy in the form of heat from the resistors.

Ah! Thanks for clearing it up!  :-[Sorry about that Rocktopus haha

It's always cool to have people like you around to teach us new things :) Thanks oldhousescott!


-Kaleb
Title: Re: Multiple LED's
Post by: gtr2 on July 08, 2011, 09:26:06 PM
Quote from: oldhousescott on July 08, 2011, 08:39:18 PM
Sorry Kaleb, but no. Whichever LED has the lowest forward voltage drop (even with LEDs of the same type) will get all the current. Put them in series, nose-to-tail. Figure a total voltage drop of about 6v for the three LEDs and calculate your dropping resistor from that.

You could put individual dropping resistors for each LED, but that would mean two more parts and extra wasted energy in the form of heat from the resistors.

Yup, I found this out the hard way once...   :D
Title: Re: Multiple LED's
Post by: bigmufffuzzwizz on July 09, 2011, 03:39:21 PM
Great example of this taken to an extreme!!!  :)
http://www.madbeanpedals.com/forum/index.php?topic=1512.0

I was surprised the first time I realized its as easy as connecting them in series..
Title: Re: Multiple LED's
Post by: JeffdaMaori on July 10, 2011, 02:31:35 AM
... may I add that those are indeed all connected in parrallel though... sorry to spread confusion....

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Title: Re: Multiple LED's
Post by: JeffdaMaori on July 10, 2011, 02:33:49 AM
... and science says that bumble bees can't fly by all principles of aerodynamics I was told...

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