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Topic: CO Alarm (Read 3 times) previous topic - next topic

brhyaa729

Ok guys I promise I will stop with the dumb questions... I have a 5 prong relay, I understand where the wires go except for the "trigger" from pin 12 on my Arduino ... using digitalWrite HIGH signal to activate the relay... where do I ground pin 12? To the 12v power supply? It seems if I ground to the Arduino it isn't a complete circuit. Please go easy on me I'm on my first cup of coffee. :-)

HazardsMind

#16
Nov 16, 2012, 05:42 pm Last Edit: Nov 16, 2012, 05:52 pm by HazardsMind Reason: 1
Put it to ground with a current limiting resistor, of say 3-5K ohms. If that is too much resistance, drop it to 1K.

Also as stated earlier, make sure you include a diode with that output, so that there is no back flow to the arduino.

DVDdoug also said,
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It needs to have a Peak Reverse Voltage rating above the relay's coil voltage, and a Forward Current rating greater than the coil current.

Created Libraries:
TFT_Extension, OneWireKeypad, SerialServo, (UPD)WiiClassicController, VWID

brhyaa729

Thanks Hazard, I have a diode on the output .... I'll stick a resistor on the neg side... the neg of the external power supply, not the Arduino correct?

HazardsMind

Wait!! If your triggering the relay with one of the pins from the arduino then you need to ground it from the arduino, unless both the external power supply and the arduino have a common ground, then it wont matter. But just in case they dont, ground it to the arduino.
Created Libraries:
TFT_Extension, OneWireKeypad, SerialServo, (UPD)WiiClassicController, VWID

oric_dan

Quote
Since I am new to this where do you guys prefer to order your parts? I'd like somewhere in the U.S.A. that is priced reasonably with fast shipping and good customer service. Of course I'd pay slightly more providing the last two criteria were exceptional.


I buy most small parts from digikey.com, mouser.com, and jameco.com. All three have inexpensive Priority Mail
shipping that typically takes only 2 days. They also all carry a lot of Arduino stuff nowadays, especially jameco.

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