Current Limiting Resisitor for LED / Optocouple r
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Posts: 46,084
Jack,
If you know the forward voltage and current, simply deduct the forward
voltage from your supply voltage and divide the result by the forward
current. eg 12 volt supply - 1.2V forward voltage / 10ma = 1080 ohms
regards,
Stuart.
Original Message
From: Jack Scasserra [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=kZGojNdPxcJfwofUXZNcU_8ltsq8KMnmF0uJbvhJJxMXzwMXqM-P4RVUVJ43OmWtg1nlAb5wvByEFj2upA]jscasserra@y...[/url
Sent: Monday, October 09, 2000 12:31 PM
To: basicstamps@egroups.com
Subject: [noparse][[/noparse]basicstamps] Current Limiting Resisitor for LED / Optocoupler
I am in need of some assistance in determining the
correct series resistor value to use for driving an
LED or an Optocoupler.
For an LED, I am assuming from all my reading that a
330ohm resistor in series is sufficient. But, if I
refer this back to calculations, I have a problem. If
I know the forward voltage and current of the LED, how
do I calculate the current limiting resistor value?
Appreciate any advice,
Jack
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If you know the forward voltage and current, simply deduct the forward
voltage from your supply voltage and divide the result by the forward
current. eg 12 volt supply - 1.2V forward voltage / 10ma = 1080 ohms
regards,
Stuart.
Original Message
From: Jack Scasserra [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=kZGojNdPxcJfwofUXZNcU_8ltsq8KMnmF0uJbvhJJxMXzwMXqM-P4RVUVJ43OmWtg1nlAb5wvByEFj2upA]jscasserra@y...[/url
Sent: Monday, October 09, 2000 12:31 PM
To: basicstamps@egroups.com
Subject: [noparse][[/noparse]basicstamps] Current Limiting Resisitor for LED / Optocoupler
I am in need of some assistance in determining the
correct series resistor value to use for driving an
LED or an Optocoupler.
For an LED, I am assuming from all my reading that a
330ohm resistor in series is sufficient. But, if I
refer this back to calculations, I have a problem. If
I know the forward voltage and current of the LED, how
do I calculate the current limiting resistor value?
Appreciate any advice,
Jack
__________________________________________________
Do You Yahoo!?
Yahoo! Photos - 35mm Quality Prints, Now Get 15 Free!
http://photos.yahoo.com/