Hey guys
I just bought some leds from http://www.computuning.com , to be precise I bought some of these : http://www.computuning.com/cgi-bin/read ... r=2&nnew=2
I know the GPO can deliver 5 volts, at a max of 20 mA ... but what's the thing with the limiting resistor ...
voltage of the led is 3.2 - 4 Volts
there are resistors included for 5V and 12V usage ..
So my question is do I connect the resistor provided with the led to the GPO aswell, or is the led by itself and the built in limiting current resistor enough ?
Just take a look at the specs of the led ...
I just don't wanna mess up my lcd ...
Thanks in advance people
Using leds on the GPO's of a BLK202A-GW-V
V = +5.0V
I = 20mA
V = IR (5 = .02A * R) = 250 Ohm (we put 240 Ohm resistors on the display)
Lets say you don't use the resistor and lets pretend the LED has 2 Ohm resistance...
V = IR (5 = I * ) = 2.5AMPS!!!! so all of a sudden, there is 2.5Amps of current being drawn, blowing up the LCD... the current limiting resistor does just that, limits the current.
Look up Ohms Law for more information
The resistor is all ready there, so go ahead and just plug in the LED.
_________________
Henry J.
Head of Technical Support
Matrix Orbital
<font size=-1>[ This Message was edited by: Henry on 2002-07-16 14:49 ]</font>
I = 20mA
V = IR (5 = .02A * R) = 250 Ohm (we put 240 Ohm resistors on the display)
Lets say you don't use the resistor and lets pretend the LED has 2 Ohm resistance...
V = IR (5 = I * ) = 2.5AMPS!!!! so all of a sudden, there is 2.5Amps of current being drawn, blowing up the LCD... the current limiting resistor does just that, limits the current.
Look up Ohms Law for more information
The resistor is all ready there, so go ahead and just plug in the LED.
_________________
Henry J.
Head of Technical Support
Matrix Orbital
<font size=-1>[ This Message was edited by: Henry on 2002-07-16 14:49 ]</font>
ok i'll use the resistor for 5V delivered with the led, service is good
got instant mail reply, package on the way
the even lowered shipping cost because the package was less than 500g
nice people imho
I do worry when use the resistor deliverd with the led for 5V use, about this passage from the manual of the BLK202A-GW-V:
Maximum allowable current is 20 mA, which is enforced by the current limiting resistor. If the device being switched has a resistance of 240 ohms or more the corresponding resistor may be shorted. Solder a small jumper wire (wirewrap wire is good) from the feedthrough hole to the corresponding negative pin for the GPO in question.
do I need to solder ??
got instant mail reply, package on the way
the even lowered shipping cost because the package was less than 500g
nice people imho
I do worry when use the resistor deliverd with the led for 5V use, about this passage from the manual of the BLK202A-GW-V:
Maximum allowable current is 20 mA, which is enforced by the current limiting resistor. If the device being switched has a resistance of 240 ohms or more the corresponding resistor may be shorted. Solder a small jumper wire (wirewrap wire is good) from the feedthrough hole to the corresponding negative pin for the GPO in question.
do I need to solder ??
It's finished
take a look at the result:
http://users.skynet.be/pirre/case.html.
on the right side a switch to control the cpu fan rpm, on the left a knob to control rpm of 3 case fans, green leds (one for mobo one for cpu temp) light when temps increase, and flash when temp is getting too high, the 3 blue leds on the left still need something to be assigned to
take a look at the result:
http://users.skynet.be/pirre/case.html.
on the right side a switch to control the cpu fan rpm, on the left a knob to control rpm of 3 case fans, green leds (one for mobo one for cpu temp) light when temps increase, and flash when temp is getting too high, the 3 blue leds on the left still need something to be assigned to
