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A nifty little LED Christmas tree made from nothing but LEDs, resistors, and a found power supply.
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This tree has made of 17 Red, Green and Yellow LEDs - the cheapest the electronics store had in stock. (no idea what manufacturer)
Their specs: (same for all colours)
forward voltage drop = 2.0V
max continuous current = 15mA
If you can, try to get LEDs that have the same specs - it's easier to design your tree.
The power supply used is from an old printer found out on the street - any sort of DC power supply will do, but the higher the voltage, the better. The one I am using supplies 30V, at up to 400mA. Enough power for 300 LEDs, but that's overkill. :-D
Their specs: (same for all colours)
forward voltage drop = 2.0V
max continuous current = 15mA
If you can, try to get LEDs that have the same specs - it's easier to design your tree.
The power supply used is from an old printer found out on the street - any sort of DC power supply will do, but the higher the voltage, the better. The one I am using supplies 30V, at up to 400mA. Enough power for 300 LEDs, but that's overkill. :-D
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i am very new to Instructables and my electronics knowledge is very basic. I need to make a circuit of 150 LEDS. But the distance between each LED will vary with the smallest distance being around 5cm and the greatest distance being about one metre. When you say:
Try not to make the distance between connected LEDs any more than twice the distance of the LED's leads, or you'll need to use extra wire (complicated)
Is there somewhere you can point me online where I can see what you mean? How complicated is it and will it make it extremely difficult if the distances between the LEDS varies?
I want to use a 12v power supply, not a batteries. Maybe LEDS are not the way to go with this project?
With a 12V power supply you can run as many LEDs as you want, but not necessarily all in series. The way to do it is to experiment with your LEDs and a resistor to see how many LEDs can be run in series, like:
12V ------[LED]--[LED]-......--[LED]----[resistor]------0V
And then build as many parallel chains of this configuration as you need for the project.
The size of the resistor will affect how bright the LEDs are.
The brightness of the LEDs will affect how much current each chain will use. (If very bright, up to 20mA)
The limit on how many LEDs you can drive will be the current rating of the power supply. If it's rated at 500mA and your chains each use 20mA, you can have up to 25 chains.
Hope that helps. :-)
OK, so I can have a single 12V power supply with multiple chains in parallel circuits running from it. I just need to do the math or...
I will use http://ledcalculator.net/ to design the circuit and ensure that I have the specs of the LEDs correct to limit problems with blowing the LEDs or them getting too hot etc.
My question is whether or not there is any loss in power if I am wiring the LEDS one metre apart? Will I have to take into account current (?) loss over the length of the wires? Or is the loss minimal?
As I am trying to wire a lot of these things over a 5 x 5m wall at varying distances I am assuming that the length of the wires will come into play when doing the math for the circuit(s) design. But maybe I am wrong?
Sorry for my ignorance and thanks for your help.
So for the maths, don't worry about the wire length.
Good luck with your project! :-)
http://ledcalculator.net
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