Does increasing the resistance increase the light intensity or decrease it? Thank you
More ohms = less LED brightness.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
Too small a resistor will cause too much current to flow through a LED and quickly burn it out.
I use this array wizard to help prime my tiny brain when doing lighting projects. It gets me started and then I go to trial and error with other resistors until I get the desired brightness.
If it makes any difference to you, differing colours will have differing percieved intensities …just to make it interesting, lol
That is a very good point. To add to the point, if you are using tri-colour LEDs (i.e. for searchlight signals) each colour will need a different resistor to get the brightness to match. If you use just one resistor on the common lead the brightness will vary between colours. Thanks to Mel for that advice.
Dave
as OP my intent is for lighting PRR yellow posiiton light signals. Thank you.
When I setup my tri-color single head signals it took three times more current for yellow than red for the brightness to look equal to my eye.
I run green at 2ma, red at 4ma and yellow at 12ma for equal brightness.
Bivar SMTL4-RGY color specs
Click on the chart above to expand
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield
I used to have a big “decade box” with rotary dials that I could dial-in various levels of resistance then note the value that gave me the brightness I desired.
Today I use this tiny replacement, using jumpers instead of the dials:
You can still get the rotary dial type but they can run into some money.
It makes choosing a resistor based on the end brightness desired much easier.
Good Luck, Ed
Ed,
Admittedly moving off topic, how did you get the foggy flavor to this great night photo?
John
I bought one of the Halloween fog machines, maybe $35-40, from Amazon. It uses glycerine in it. I only use it occasionally for some photo shoots. The fog is odorless and, as far as I can tell, has no lasting effect on the layout.
There are a bunch out there. I bought mine maybe four years ago, something like this one: https://tinyurl.com/rhuduo9
IMG_3599_fix by Edmund, on Flickr
Thanks for asking [:D][Y] Ed
Nice. Thanks, Ed.
When near my trains, I’m often in a fog. But it doesn’t show up in photos.
John