# LED Christmas Tree

## Step 3: Design - aesthetic

Artistic skills time!

When designing your tree just remember:

1. It has to be an electrical circuit (see previous step), and so try and visualise the path the electricity takes.

2. 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)

If you look at the design B, you can see that there are two paths between the two terminals. The wires on the underside of the lowest green LEDs only connect to one terminal, and bypass them on the way around the outline of the tree. The other terminals of the lowest green LEDs are connected through the resistor, making two parallel circuits.
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ashcooper4 years ago
Nice instructable.

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?
MrTrick (author)  ashcooper4 years ago
Thank you!

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.  :-)
4 years ago
Thanks for the reply.

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.

MrTrick (author)  ashcooper4 years ago
There is no problem having longer wires. The only reason I stipulated putting the LEDs close together for this instructable was that they're soldered directly from one to the next. If they were further apart you have more joints to solder.

So for the maths, don't worry about the wire length.

Good luck with your project! :-)