LED''s In Series.....

Archiver

By the way, this is a Basic Stamp project - although slighly off topic. I
figure that if I have this question, someone else must too.

Tim

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Original Message

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From: Nicholas Judson <judson@f...>
To: Basic Stamp List <basicstamps@yahoogroups.com>
Date: Sunday, April 15, 2001 4:35 PM
Subject: Re: [noparse][[/noparse]basicstamps] LED's In Series.....


>20 mA -- use the 120 Ohm resistor.
>
>for LEDs in parallel, the current is summed.
>
>
>Nick
>
>On Sun, 15 Apr 2001, Tim and Jo wrote:
>
>> I have a question about wiring LED's in series. LED Requirements:
>> Voltage Drop of 2.4V at 20mA. Supply Voltage: 12VDC. I'd like to put
four
>> in series using just one current limiting resistor. I understand that I
>> should add-up the total voltage drop for the four in series, but my
question
>> is, should I divide this by 20mA or by 80mA to calculate the resistor
value?
>> In other words should the series be allowed 20mA total or should I figure
>> 20mA for each LED?
>>
>> 2.4V x 4LED's = 9.6V Total Voltage Drop.
>>
>> 12V - 9.6V = 2.4V Remaining.
>>
>>
>> 2.4V / 20mA = 120 Ohm Resistor?
>> OR
>> 2.4V / 80mA = 30 Ohm Resistor?
>
>
>
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