Brind
Newbie level 3
string 9 leds series
I am planning to use a 12 volt regulated supply and two circuit boards, each having 54 LED's.
Each board will have 6 LED's across the width and 9 LED's in length. (simple rectangle shape)
This is where I get stuck.
I've heard LED's can vary from batch to batch so connecting too many in Parallel isn't a good idea. So I can't just wire all the LED's together and put one resistor in the circuit.
I'm hoping to use one resistor per 6 though, hopefully where my 6 LED's across (in my circuit) will finish, so each row of six will be wired in Series with a resistor on the end and then each row will be wired in Parallel until all 9 rows are powered by the 12v supply.
Am I correct in thinking this is ok and will work and will be efficient?
I don't know how many mA to supply each one either, I have the LED's and it's stated they can take 50mA, but I'm guessing that generally they are happy at running at 20mA.
1, Would there be much difference in brightness?
2, Reliability, is crucial, so is it best to stick to 20mA anyway?
3, Because I'm using 12v, if I want each LED to run at 50mA I'd end needing a transformer with big amperage output since I want to power 108 of them?
4, Am I correct in thinking that if I supply 108 LED's with 20mA each that I'd need a transformer that is capable approx 2.2 Amps?
Thanks for any help!
Mark.
I am planning to use a 12 volt regulated supply and two circuit boards, each having 54 LED's.
Each board will have 6 LED's across the width and 9 LED's in length. (simple rectangle shape)
This is where I get stuck.
I've heard LED's can vary from batch to batch so connecting too many in Parallel isn't a good idea. So I can't just wire all the LED's together and put one resistor in the circuit.
I'm hoping to use one resistor per 6 though, hopefully where my 6 LED's across (in my circuit) will finish, so each row of six will be wired in Series with a resistor on the end and then each row will be wired in Parallel until all 9 rows are powered by the 12v supply.
Am I correct in thinking this is ok and will work and will be efficient?
I don't know how many mA to supply each one either, I have the LED's and it's stated they can take 50mA, but I'm guessing that generally they are happy at running at 20mA.
1, Would there be much difference in brightness?
2, Reliability, is crucial, so is it best to stick to 20mA anyway?
3, Because I'm using 12v, if I want each LED to run at 50mA I'd end needing a transformer with big amperage output since I want to power 108 of them?
4, Am I correct in thinking that if I supply 108 LED's with 20mA each that I'd need a transformer that is capable approx 2.2 Amps?
Thanks for any help!
Mark.