Author Topic: 2 LEDs for one pedal?  (Read 1125 times)

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StevenJM

2 LEDs for one pedal?
« on: February 29, 2012, 04:57:12 PM »
I'm thinking about building an enclosure where the pedal has 2 LEDs that light up when the pedal is turned on.

I'll be building from a General Guitar Gadgets circuit board that puts a 1M resistor before the LED light.  What would have to change, or would I keep that resistor the same? 

This is my first post, I'm new to making pedals, so i'm trying to gather as much info as I can.

Thanks guys.

runmikeyrun

Re: 2 LEDs for one pedal?
« Reply #1 on: February 29, 2012, 06:01:32 PM »
Hey Steven, welcome  :)

Can you post a link to the schematic of the project you're building?  Also, 1M LED resistor seems WAY high, usually around 2.8k or so. 

If you post the schematic link someone can probably help.
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digi2t

Re: 2 LEDs for one pedal?
« Reply #2 on: February 29, 2012, 06:05:21 PM »
Sounds to me like the 1M is the pull down resistor. The LED resistor should be a smaller value. Like mikey says, please post the schematic.

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Dino
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StevenJM

Re: 2 LEDs for one pedal?
« Reply #3 on: February 29, 2012, 06:28:12 PM »
My fault... i knew it didn't look right when I typed it.  They have a 1K resistor in front of the LED. 

http://www.generalguitargadgets.com/pdf/ggg_secf_lo.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

R10 = 1K resistor.

LucifersTrip

Re: 2 LEDs for one pedal?
« Reply #4 on: February 29, 2012, 08:08:28 PM »
What would have to change, or would I keep that resistor the same?  

the 1K is not set in stone. you can set it to any level you want.  just put a 10K pot in there and find the brightness which is cool for you, then sub a resistor for the measured value on the pot. don't turn to 0K or you'll blow the led.

...and don't test it with a dead battery
always think outside the box

Beo

Re: 2 LEDs for one pedal?
« Reply #5 on: February 29, 2012, 08:52:13 PM »
And for two LEDs, just connect a second one in parallel. The resistor is called a "current limiting" resistor. Without it, 9 volts will charge through your LED and blow it instantly. You probably don't need a second resistor, as the first one serves a common purpose. Adjusting its value will control how much current flows through the LED, and how bright it will be. Then again, if you want to dial in the brightness for each LED (for instance, different colors), you may want an individual resistors for each LED.

LucifersTrip

Re: 2 LEDs for one pedal?
« Reply #6 on: March 05, 2012, 08:30:35 PM »
...and you will even notice that 2 LEDs of the same color aren't even the same brightness. I had to go thru a bunch of LEDs so I could match em for that Fuzz Skull over there on the left...
always think outside the box

PRR

Re: 2 LEDs for one pedal?
« Reply #7 on: March 05, 2012, 09:10:31 PM »
Put the 2 LEDs in _series_. Yes, parallel can work, but the two LEDs don't always share current equally. With odd-lot LEDs one is sure to hog the current. In series they MUST both pass the same current.

Because the stacked LEDs need more voltage, there is less voltage on the resistor, and less total current. Usually this is moot. There's no "right" current. If they seem dim, reduce the resistor value a bit.

This may not work so well with White LEDs. Two of these need over 6V leaving very little resistor drop from a 9V battery.

The other way is 2 LEDS and _2_ resistors. Same as plugging-in a second room-lamp. Just remember that a room-lamp has the necessary resistor, an LED always needs an external resistor (or other trick) to set its power/brightness.