15-03-2008, 21:06
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CaMOElot, it is a silly place
AKA: My First Name is really "The" (or Brian)
 FRC #0365 (The Miracle Workerz); FRC#1495 (AGR); FRC#4342 (Demon) Team Role: Mentor
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Join Date: Mar 2002
Rookie Year: 2001
Location: Dela-Where?
Posts: 1,564
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Re: Can Relay Outputs Directly Drive LEDS ? (for testing)
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Originally Posted by Don Rotolo
For the price of an RC I would research the spec myself; however if an LED draws 15 mA and the output can source 15 mA or more, then the answer is yes.
While you are looking at those specs, also see what the output can "sink" - that is, how much current can it allow to flow when it acts as a ground (and not a power 'source'). Most circuits can sink two or more times the current that they can source. If you want to do this, connect the anode of the LED to +5v, and the cathode (through a dropping resistor, maybe 82 to 120 Ohms) to the digital (relay) output pin.
Don
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This IFI FAQ entry should be of interest.
One of the questions in the thread is:
Quote:
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Originally Posted by IFI FAQ
Could we use the charge from a Digital I/O pin set on the RC to power a single solenoid, or do we have to go through the relay pins and a spike?
You must follow FIRST Rules. As for is it possible, you must check the current required for your solenoid, the Digital pins can only source about 7mA.
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__________________
Electrical & Programming Mentor ---Team #365 "The Miracle Workerz"
Programming Mentor ---Team #4342 "Demon Robotics"
Founding Mentor --- Team #1495 Avon Grove High School
2007 CMP Chairman's Award - Thanks to all MOE members (and others) past and present who made it a reality.
 Robot Inspector
"I don't think I'm ever more ''aware'' than I am right after I burn my thumb with a soldering iron"
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