LED Tester?

[soupbone]

Is there some way of testing to see what the color and brightness is of an led is,without having to solder into a circuit?

[jkokura]

A battery, a 4.7K resistor, and three alligator clip wires.

Jacob

[soupbone]

A battery, a 4.7K resistor, and three alligator clip wires.

Jacob

How is this done exactly?Do you have a pic or diagram you might be able to send me?Also,When you say alligator clip wires are you talking about the one's that you use for a multi-meter?Thank you for your help!!

[.Mike]

How is this done exactly?Do you have a pic or diagram you might be able to send me?Also,When you say alligator clip wires are you talking about the one's that you use for a multi-meter?Thank you for your help!!

Alligator clips (test leads): http://www.harborfreight.com/18-inch-low-voltage-multi-colored-test-leads-66717.html

Clip one test lead to the battery positive. Clip the other end of that test lead to the resistor.

Clip another test lead to the other side of the resistor. Clip the other end of that test lead to the positive side of the LED.

Clip another test lead to the negative side of the LED. Clip the other end of that test lead to the battery negative.



Mike

[Maik]

Check your voltmeter. Can you check transistors with that? If yes-C and E on PNP. Put the LED in and it will light up.

[soupbone]

Right on!Thanks fellers for the ideas!

[ayayay!]

Sometimes the easiest solution is the most overlooked.  Go to Walgreens/Walmart, go to the hearing aid section, find a 3 ~ 3.2v battery.  Keep it handy in your LED drawer.  Done.  

[MikeH]

Sometimes the easiest solution is the most overlooked.  Go to Walgreens/Walmart, go to the hearing aid section, find a 3 ~ 3.2v battery.  Keep it handy in your LED drawer.  Done.  

This works well- so does a really dead 9v.  Measure it with your volt meter - find one down around 2-3 volts and label it, or keep it someplace specific.

Otherwise, I generally just pinch the LED and resistor together w/ my fingers, and put the two floating leads up to a battery, or wallwart cable.  That works fine too.

[Gus]

If you want to pick a standard current for your builds using different LEDs you might want to build a constant current circuit set to the current you picked.

You can use a battery and a resistor.  If you know the LED voltage drop and power supply voltage at the current you want you can use Ohms law to find the resistor value.

FWIW if one wants to build effects a little above the paint by number level,  IMO you need to know how to use the simple DC math with Ohms law

Google, Bing etc Ohm's law, LED voltage drop etc.

[ayayay!]

You're dead on, Gus!  Except for Bing...

[deadastronaut]

i always leave a couple of resistors on my breadboard in the corner for led tests..always handy..

[Paul Marossy]

Here's mine, all made from junk I had lying around. Four 1.5V batteries and a 330 ohm current limiting resistor. Insert LED into permanently mounted alligator clips and then press momentary switch to test.



I made this because I was getting a lot of dead LEDs lately, and it's quite frustrating to find out that they are dead after you've already completely assembled a pedal and are ready to box it up for shipping.

[ayayay!]

This reminds me, I had a totally new one come up on me last night.  Wired up this pedal, everything worked on the first try except for the LED.  No problem, I figured.  Huh, yeah right. 

Touched the two extended leads to the DC jack.  Nothing.  Disassembled the leads and took my trusty 3.2v battery to the LED legs, fires up.

Okay, so it's my extended wiring then.  Nope, tested and retested with the wiring, ohm'ed out my current limiter at 4.7k as it should have been.  Very weird.

So then I tried my continuity (speaker) setting through the - LED lead -> resistor.  Nothing!  So bizarre, but after I swapped that resistor out it was all fine.  Tried the resistor on another LED and nothing through it would light up.  Anyone have a resistor that ohm'ed out OK but doesn't pass any current?  It was nuts!

[soupbone]

Here's mine, all made from junk I had lying around. Four 1.5V batteries and a 330 ohm current limiting resistor. Insert LED into permanently mounted alligator clips and then press momentary switch to test.



I made this because I was getting a lot of dead LEDs lately, and it's quite frustrating to find out that they are dead after you've already completely assembled a pedal and are ready to box it up for shipping.

Wow!That's cool Paul!

[LucifersTrip]

Is there some way of testing to see what the color and brightness is of an led is,without having to solder into a circuit?

To get the brightness you want, set the pot to where you like it, disconnect, then measure it.


remember, never turn the pot all the way counterclockwise (0 resistance) or you'll blow the LED, and lose 3 pennies

[Paul Marossy]

Is there some way of testing to see what the color and brightness is of an led is,without having to solder into a circuit?

To get the brightness you want, set the pot to where you like it, disconnect, then measure it.


remember, never turn the pot all the way counterclockwise (0 resistance) or you'll blow the LED, and lose 3 pennies

Cool idea. Just make sure that you always have some minimum resistance in series with that pot so you don't fry the LED when the pot is at zero resistance.

[deadastronaut]

bang!..

[Paul Marossy]

I've found that they make more of a popping noise than a bang.  

[deadastronaut]

ive had a few just 'fizzle'....

[Paul Marossy]

ive had a few just 'fizzle'....

Actually, same here. I hate it when I kill an LED!