LED question
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Joined: May 2008
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as said above,
it would depending on the voltage source, the forward voltage drop of the LEDs and the current draw. with all of that information, you can calculate the resistance needed.
just approximately, four leds in series, probably around 200-300 ohms...
John
BT
it would depending on the voltage source, the forward voltage drop of the LEDs and the current draw. with all of that information, you can calculate the resistance needed.
just approximately, four leds in series, probably around 200-300 ohms...
John
BT
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Member
Joined: Jan 2009
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From: Houston, TX
Wow I didn't know they had calculators for that, I broke out the old pencil/pad and came up with 220 ohms. I just wanted someone to come up with hopefully the same numbers on their own so I knew if I was right or wrong. Thanks
July 2008 ROTM
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From: Milwaukee
http://www.oznium.com/led-resistor-calculator
Also an amazing site for tons of LED and other lighting.
Also an amazing site for tons of LED and other lighting.
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Typically 6 ohm 50 watt resistors are used across each led light housing to simulate the normal current flow. If you just want to tap into one line instead you can run four of them parallel or one, umm, 1.5 ohm 130 watt resistor, will flow the same amount of current as the four 6 ohm ones. Due to reasons of heat and availability your better off going with the four 6 ohm'ers, one across each led. better yet get a variable load flasher unit and replace your stock one with it. They don't require current flow to toggle the blinkage and remove the need to add resistors. If you want the resistors they sell them on ebay and elsewhere specifically for this. http://cgi.ebay.com/ebaymotors/ws/eB...%3AIT&viewitem=
Member
Joined: May 2008
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50 watt resistors? 6 ohms? ... *confused* ... why would you put LEDs in parallel (more current draw)?, 1.5ohm 130 watt resistor???? uh... you mean a LIGHT BULB ???
I'm not sure he was inquiring about load resistors to slow down his flash rate.
John
BT
I'm not sure he was inquiring about load resistors to slow down his flash rate.
John
BT
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From:
I think people are talking about 2 different things. Rock is trying to figure out what resistor to use in series with the LED's to get the rated current (probably ~20mA) through them and Hangfire is talking about a resistor used to get the correct flash rate.
With 4 LED's (1.7V drop, 20mA current) in series, you would need a 360 Ohm, 1/4 watt resistor in series with the LED's. If the LED's have 2V drop and 20mA, you would need a 300 Ohm, 1/4 watt resistor in series. This assumes a 14V (~voltage with bike running)battery system.
With 4 LED's (1.7V drop, 20mA current) in series, you would need a 360 Ohm, 1/4 watt resistor in series with the LED's. If the LED's have 2V drop and 20mA, you would need a 300 Ohm, 1/4 watt resistor in series. This assumes a 14V (~voltage with bike running)battery system.
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viva_brasil
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Jun 9, 2008 04:38 AM
