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Class : Apprenti
Posts : 7
Registered on : 30/12/2007
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I purchased some 5 mm IR LEDs from Radio Shack, the specs are as follows:
Radiant power output (100mA): 16mA min
Forward Voltage: 1.2V
Forward Current: 100mA
Absolute maximum ratings –
Forward voltage (20mA): 1.6V
Reverse voltage: 5V
Forward current 1.2A
Reverse current: 10uA
Wavelength: 940nm
Followed the instructions from the 3point clip pdf. Using the calculator, and confirming with an LED calculator from another site, I purchased a ½-watt 68-Ohm 5% resistor for use with a USB line running the LED at 1.2V and 60mA. I’ve hooked up the positive to the positive lead on the LED and the ground to the negative lead, but my LED does not light up. (Meanwhile if I plug it into an Iona thumb LED that I’ve removed the original LED from, the IR LED lights right up.)
Did I get the wrong resistor? Or is more likely a problem with my new soldering skills? I’m new to small electronics, so I don’t know what I’m doing, really.
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Class : Apprenti
Posts : 7
Registered on : 30/12/2007
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Alternately, if anyone can give recomendations for the resistor to use with a 9v battery setup, I might try building that as a second attempt.
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Class : Apprenti
Posts : 6
Registered on : 21/12/2007
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play with the LED calculator and you should see what you need to do. It looks like for your setup running 80 mA through the resistor you need one 68 ohm 1/2 watt resistor. The LEDs will be wired in series.
The USB attachment makes me nervous. I would stick to batteries if I were you.
flips
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