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Can't make LED circuit work
Satsumomo
Rated PG!Registered User regular
Rated PG!Registered User regular
EDIT: WOOPS! Solved it myself! Firstly I forgot they were IR leds so obviously I couldn't see them. But they still wouldn't show up on FreeTrack.
Then I realized I was using the wrong spec-sheet, and that I had used the wrong +/- sides on the LEDs. I inverted them and voilá! They work!
Hey there guys!
Well I'm a complete beginner in building circuits. This is the first time ever I've tried building one.
I'm currently trying to get a FreeTrack cap working, so I need to have 3 IR leds light up. Using a calculator they have at their site, I wanted to get 50mA out of the IR LEDs.
Their specs are as follows;
5mm
1.3v
20mW max
I'm trying to power them up with a 9V battery, so the calculator says I need a 100ohm resistor, which should output a 51mA.
This is how I wired them:
Weird thing is that using a multimeter, I don't get any resistance reading at all if I put each wire on the LED ends, so basically the circuit stops at the first LED. This is true for all 6 LEDs I bought. Did I get a really bad batch? I even just put one LED on the 9V battery terminals directly, and nothing happens.
What's going on here?
Then I realized I was using the wrong spec-sheet, and that I had used the wrong +/- sides on the LEDs. I inverted them and voilá! They work!
Hey there guys!
Well I'm a complete beginner in building circuits. This is the first time ever I've tried building one.
I'm currently trying to get a FreeTrack cap working, so I need to have 3 IR leds light up. Using a calculator they have at their site, I wanted to get 50mA out of the IR LEDs.
Their specs are as follows;
5mm
1.3v
20mW max
I'm trying to power them up with a 9V battery, so the calculator says I need a 100ohm resistor, which should output a 51mA.
This is how I wired them:
Weird thing is that using a multimeter, I don't get any resistance reading at all if I put each wire on the LED ends, so basically the circuit stops at the first LED. This is true for all 6 LEDs I bought. Did I get a really bad batch? I even just put one LED on the 9V battery terminals directly, and nothing happens.
What's going on here?
Satsumomo on
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Any diode (LED's are light emiting diodes) will show minimum to no resistance in between their terminals when polarized. That's because diodes are designed to let current flow in one direction and not in the other: if you turn off the polarization of the diode, you should get maximum resistance.
A better way to test diodes, including leds, is to put your multimeter in diode testing mode, usually included in the conductivity test mode, but not always. If the component gives you a small voltage value like 0.7V for Si diodes, or around 1.2V for leds, it means the LED is working.
*kowtows*
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