LED''s In Series.....
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Posts: 46,084
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?
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?