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<div class="moz-cite-prefix">I would. I would also disconnect the
Vcc line to R1 from the on-board Vcc and instead connect it to the
R'Pi's Vcc line.<br>
<br>
That relay board is designed to work with the more tolerant
Arduino 5V I/O pins, not the delicate 3.3V R'Pi GPIO pins.
Separating the optoisolator's input from the rest of the board
keeps the R'Pi's outputs from driving anything but an LED.<br>
<br>
I've got an almost identical 4-relay board from SainSmart<br>
(<a class="moz-txt-link-freetext" href="http://www.amazon.com/gp/product/B0057OC5O8/ref=oh_details_o03_s00_i02?ie=UTF8&psc=1">http://www.amazon.com/gp/product/B0057OC5O8/ref=oh_details_o03_s00_i02?ie=UTF8&psc=1</a>)<br>
same schematic per channel, and that is how I got mine to work
safely.<br>
<br>
On 11/03/2013 05:40 PM, Lucas Rumney wrote:<br>
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<div dir="ltr">So in order to use this board, I would desolder the
surface mounted R1, and put in its place a normal thru-hole
120ohm resistor if I wanted to keep the LED there? <br>
<br>
It would be easier to just keep the LED there, right? so I dont
have to desolder it too? </div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Sun, Nov 3, 2013 at 5:10 PM, Scott
Hall <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:scottghall1@gmail.com" target="_blank">scottghall1@gmail.com</a>></span>
wrote:<br>
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<div>Excellent catch for newby. It is by no means the
only way to approach the problem, but a very effective
one.<br>
<br>
The 2mA draw of the LED in the optoisolator is well
within the GPIO pin specs of the Raspberry Pi.<br>
<br>
However make sure that you use a separate 5V supply to
power the relay board, but you can power the opto- LED
from the R'Pi's 3.3V power if you use a 470ohm resister
(R1) instead and forgo the extra LED (IN1), or use a
120ohm resister if you keep the extra LED.
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<pre class="moz-signature" cols="80">--
Scott G. Hall
Raleigh, NC, USA
<a class="moz-txt-link-abbreviated" href="mailto:ScottGHall1@GMail.Com">ScottGHall1@GMail.Com</a>
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