Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Dimming LEDs

Status
Not open for further replies.

wrinkledcheese

New Member
Is it possible to give an LED a lower voltage and make it dimmer, faking the shades? I thought of a project I've been putting off for a while and it could hole me over until I find the info I need for getting another project I have on the go off the ground. I don't think there are multiple shades of LED's but dimmed LEDs would work just as well, it would give me the desired effect.
 
Of course! But more specifically, you need a lower current.
We never supply an LED with a constant voltage, the current it draws is completely unpredictable and it usually destroys itself if it's high enough to turn on.
A series resistor limits the current, either increasing the resistance or lowering the source voltage will dim the LED.
 
Keep in mind that most white LEDs (single die), because how it's designed, will change colors as current is changed. This is due to the phosphor used on the die to convert some of the blue light to orange-ish light. At low current, not enough orange-ish light is created to cover up the blue, and hence it tends to look more blue.

All other single-color LEDs don't change their hue much as current changes up until it's ready to kill it or it shuts off. If you want to try something expensive you could get those RGB LEDs and program each die to your own current and thus get almost any color out of it.
 
Actually I just want to finish the case mod in my computer. I had this idea of a leaf and using fully light LEDs for the stem and use different dimmed LED's for the leaf. I plan on getting Plexiglas that is thick enough to put LEDs into, I don't want to spend too much on the LEDs because that would be expensive because of the number of LEDs I want to use. The only problem I can see is: I'm going to have to polish the Plexiglas holes once I've drilled them and, I'm going to have to hope my power supply has enough power left over to power ~ 100+ LEDs. May even be as high as 300+. If not I will have to get a more powerful power supply OR get a second power supply for just the LEDs.
 
I remember a post about a year ago, where some guy wanted to run 60 or so LEDs directly from 120 mains. Don't remember if he ever came back and told of his results, or if it was ever tried. Seems it can be done, got about 10 strings of LEDs last Christmas (about $2.00 each).

I just did a 10" X 10" piece of thick black plexi with 25 cheap flashing red LEDs spaced 2" a part in a grid. Gives pretty good random looking patterns. It's solar powered (guts from a yard light, upgraded to 3.6 volts). Still flashing at 2:00 AM, but maybe half bright when I leave for work.
 
HarveyH42 said:
I remember a post about a year ago, where some guy wanted to run 60 or so LEDs directly from 120 mains. Don't remember if he ever came back and told of his results, or if it was ever tried. Seems it can be done, got about 10 strings of LEDs last Christmas (about $2.00 each).

It can be done, but there's still a current limiting resistor. I took apart a junk exit sign once, the LEDs were wired in series (over two dozen) with the resistor, so they'd flash @ 30Hz but it was fast enough to not really notice it, especially through the red letter filter.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top