hi all,
ok im new to all this lighting stuff so i need your help, i have just bought these 3mm LED's and want to know how many of them i can chain together whilst using a small square battery with out having to buy resisitors...see links below for LED and battery information.
LED's
http://www.ebay.co.uk/itm/121255201707? ... 1497.l2648
battery
http://www.tesco.com/direct/maplin-extr ... 6-1206.prd
lighting help needed
Moderators: Sparky, Moderators
lighting help needed
ScaleModelWorld.net
"The most efficient killing machine ever invented and you've got it doing laundry" John Connor
"The most efficient killing machine ever invented and you've got it doing laundry" John Connor
yeah i bought a dozen white and a dozen blue 3mm LED'sbrt wrote:You have a 9 volt battery. Did you buy more than 1 color? The chart for the LEDs shows the voltage range for each color.
ScaleModelWorld.net
"The most efficient killing machine ever invented and you've got it doing laundry" John Connor
"The most efficient killing machine ever invented and you've got it doing laundry" John Connor
-
- Posts: 1818
- Joined: Sat Mar 05, 2005 9:16 am
- Location: Serenity.
- Contact:
Ummm.. thats not such a good idea.
LEDs are really current mode devices which means that they may happen to have X volts across them while running, but that can change with temperature and other things.
For a really simple circuit, add a resistor, even if its just 100 ohms, to limit the current to a safe value.
A better way is to control the current in the string, which is more complicated but thats how my controller does it.
LEDs are really current mode devices which means that they may happen to have X volts across them while running, but that can change with temperature and other things.
For a really simple circuit, add a resistor, even if its just 100 ohms, to limit the current to a safe value.
A better way is to control the current in the string, which is more complicated but thats how my controller does it.
That Madman Who Lit Up Deep Space Nine
- Mr. Engineer
- Posts: 440
- Joined: Mon Dec 10, 2007 6:01 am
- Location: Malaysia
- Contact:
+1 for Madman
The current limiting resistors are there to protect the LEDs from burning out.
Each colour of LED have their own voltage and current rating, here are some general ones:
RED = 1.8v, 20mA
GREEN = 2.2v, 20mA
White = 3.2~3.5v, 25mA
Blue = 3.2~3.5v, 25mA
You can put almost three White LEDs in series for the 9volt battery (square battery) but whatever you do, they still need a small resistor. IMHO, I always prefer parallel LEDs and with it, their own personal resistors. I then do not have to worry about extra energy loss (the excess 5.8volts the resistor has to waste as heat.)
The current limiting resistors are there to protect the LEDs from burning out.
Each colour of LED have their own voltage and current rating, here are some general ones:
RED = 1.8v, 20mA
GREEN = 2.2v, 20mA
White = 3.2~3.5v, 25mA
Blue = 3.2~3.5v, 25mA
You can put almost three White LEDs in series for the 9volt battery (square battery) but whatever you do, they still need a small resistor. IMHO, I always prefer parallel LEDs and with it, their own personal resistors. I then do not have to worry about extra energy loss (the excess 5.8volts the resistor has to waste as heat.)