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Author Topic: Good relays for larger LEDs.  (Read 748 times)
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Bergen, Norway
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Im going to run 2-4 3W IR leds on 8,4V on an arduino. Want the relays to be as small as possible to save space. Any good sugestions?
Was thinking about this one.

http://cgi.ebay.com/Arduino-4-Route-MOSFET-Button-IRF540-/280525487095?pt=LH_DefaultDomain_0&hash=item41509f3bf7


Karl
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The MOSFET need to operate higher then 9V.
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Good choice, it's compact, powerful and optocoupled!
Your arduino board will be on the safe side of the road, if anything goes wrong with LEDs.
Transfer characteristic chart shows, that it become conductive starting from 5V,
and it's good with 8.4V if current less than 20A, that is more than enough in your case.
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Couple of questions:  8.4V seems high for an IR LED - are they running in series?  Is there a reason you need a relay?  I single MOSFET or Darlington would do the job otherwise.
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Im going to run 2-4 3W IR leds on 8,4V on an arduino. Want the relays to be as small as possible to save space. Any good sugestions?
Was thinking about this one.

http://cgi.ebay.com/Arduino-4-Route-MOSFET-Button-IRF540-/280525487095?pt=LH_DefaultDomain_0&hash=item41509f3bf7


Karl

Well you state wanting to use relays but linked to a 4 channel solid state mosfet switching board, which do you really want to use, either will. That appears to be a nice board you linked to, but the only caution, it is not using logic level mosfets, so it's relying on the applied battery voltage to be high enough to fully turn on the mosfets, they suggest 9vdc as a minimum. However your 8.4 volt voltage source is probably close enough to work OK at the current levels of your led arrays.

Lefty
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Bergen, Norway
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Im running 3 single watts in series. total of 4,5v and 700mA. The leds have a driver and a voltage step down to suit 8,4 Volt batts. Im running them on 7,4V lipos. (7,4-10,4 actually)  But its no trouble getting smaller or larger lipo batt if needed.

Im not shure whats suits my application. But the link posted seemed to be right for my needs.


Karl
« Last Edit: February 26, 2011, 02:01:51 pm by Wracul » Logged

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I have that 4- Power FET brick here also, and for less (DISCLAIMER: My Shop):
 =FET&s[title]=Y&s[short_desc]=Y&s[full_desc]=Y&s[sku]=Y&s[match]=all&s[cid]=0]http://arduino-direct.com/sunshop/index.php?l=search_list&s[search]=FET&s[title]=Y&s[short_desc]=Y&s[full_desc]=Y&s[sku]=Y&s[match]=all&s[cid]=0

I have asked the developer of this unit for the schematic and hope to post it soon...
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Regards, Terry King  ..On the Red Sea at KAUST.edu.sa
terry@yourduino.com  LEARN! DO! (Arduino Boards, Sensors, Parts @ http://yourduino.com

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