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TOPIC: Need resistor help:
Need resistor help: 1 year 5 months ago #62218
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Working on a new mhs build, need a resistor for a black 12mm purple AV switch. Tcss didn't have any dynaohm in stock when I ordered. The resistor calculator says 39ohm 1/8 watt. Radio shack has a few 1/8 watt resistors but not 39 ohm. I am not sure how close I need in the ohms so I don't blow the AV led.
Any help would be greatly appreciated... |
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Need resistor help: 1 year 5 months ago #62262
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What soundboard (if any) and power supply (voltage-wise) are you using in this build?
Edit: Also, if using a soundboard, are you wiring to an accent LED pad or direct to the switch? |
Need resistor help: 1 year 5 months ago #62263
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50ohm will get you ~20mA on a fresh lithium-ion at ~4v, and ~14mA at 3.7v.
35ohm will overdrive the LED to about 29mA on the fresh 4v lithium-ion but have it at 20mA at the usual 3.7v. So anything between 35-50ohms should be fine. Anything under 35 (and maybe even the 35 itself) risks blowing out the LED. Anything over 50 will prevent it from ever running at maximum brightness. All this assumed a single 3.6-3.7v lithium-ion though. Different power solutions would change calculations. |
Need resistor help: 1 year 5 months ago #62269
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Snakeeyz99 wrote:
What soundboard (if any) and power supply (voltage-wise) are you using in this build?
Edit: Also, if using a soundboard, are you wiring to an accent LED pad or direct to the switch? Nb v3, 3.7 protected, direct to switch |
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Need resistor help: 1 year 5 months ago #62270
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I'd almost say give it a week, they're pretty quick to restock the smaller stuff.
Edit: Google'ing the item gives some trusted sources as alternatives: http://www.digikey.com/product-detail/en/leddynamics-inc/4006-025/788-1090-ND/3114411 https://www.superbrightleds.com/moreinfo/resistors/led-resistor-dynaohm-dc-constant-current/1054/ |
Need resistor help: 1 year 5 months ago #62272
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Kouri wrote:
So anything between 35-50ohms should be fine. Anything under 35 (and maybe even the 35 itself) risks blowing out the LED. Anything over 50 will prevent it from ever running at maximum brightness. Cool thx... Pretty sure they had 50 @ rs Can you change the watt or is that a must? |
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Need resistor help: 1 year 5 months ago #62273
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BoostinIX wrote:
I'd almost say give it a week, they're pretty quick to restock the smaller stuff.
Tcss has what I need now but I don't want to pay to ship one resistor... Or wait for that matter |
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Need resistor help: 1 year 5 months ago #62278
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Burns3558 wrote:
Kouri wrote:
So anything between 35-50ohms should be fine. Anything under 35 (and maybe even the 35 itself) risks blowing out the LED. Anything over 50 will prevent it from ever running at maximum brightness. Cool thx... Pretty sure they had 50 @ rs Can you change the watt or is that a must? Any wattage that can handle the max power through the resistor will do, but no less or the resistor might burn out. For a 50 ohm at 4V the max power is (4.0V-3.0V)*(0.02A)=0.02W (or 1/50W). Odds are all resistors you'll find in Radioshack are 1/8W or above, so any of those should do, but a 1/16W should work as well if you find one. I wouldn't go as low as 1/32W, though, since if the battery goes to 4.2V you start losing a lot of your power-handling headroom. |
Need resistor help: 1 year 5 months ago #63721
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Boost thanks btw... Grabbed a few from superbright and they arrived in 2 days.
So basically to wire an led av switch to a nb v3 I will connect the positive for the switch led to the positive on the saber led with a dynaohm in the switch led positive wire and wire the switch led negative to the saber led negative? Would it be easier to just wire the switch led to the pos and neg on the nb? (With the dynaohm in the positive line) Not sure what makes more sense...? |
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