Monday, 21 November 2016

How to Wire Strings of Micro Leds

For those of you coming back to this post please note I have reduced the resistor from 36 Ohms to   15 Ohms for 200 lights or less.

The first thing I would like to say is that I have put this extensive post on my blog, on how I wired this particular board in my model, for three reasons. One, I have a head like a sieve. I do soo much stuff that I forget what I am doing. This way I can come back on it and go "Ah ha! Is that what I did!" The other reason is that when I was young, and attempting to learn all of this stuff, I had to figure it out by myself because no one would tell me. It took years! I suppose their idea was that it had taken them so long to figure it out why should they just give the information away for free? In one way I don't listen that, on another, I can understand it. So you can use this information, although I take no responsibility if you follow it and it does not work, for free BUT I would really appreciate it if you could link back to my blog. Also, in the future, I am going to do an e-book on how my models were made and this is a good start, although I think I might add videos to that.
This is the effect that I was aiming for and I am very pleased with it.
The second thing I need to say is that I am NOT an electrician and so I have wired these micro LEDs as a novice. This works for me but if you are going to follow in my footsteps and have any reservations please contact an authorised electrician. Always be careful when dealing with electricity.

I have probably said this before in other posts but I will say again - wiring lights are the bane of my life. There are soo many ways to wire lights and it can really become a very complicated thing. As I am not a person for complication I  believe I (after all these years) I have figured out a simple way for me to use LED lights within my model.

I am presently going through Pebble Cottage changing the lights. It is a model that is approx 20 odd years old and was filled with 'rice bulbs'. These chew up a large amount of power to run and so I have been methodically going through each section (7 of them) and changing them to LEDs.

I am using two types of LED's. The first are the individual 3mil and 5mil bulbs. These are mainly used inside the houses. The other type is the fantastic strings of micro LED's (Fairy Lights) with an added decoration over the top. Later I will be using the tape LED's for the fungi I want to light up and using Optic Fibre within the model.

I am also making it so the models can run on battery and also mains power through a 12v transformer which means that the 3mil & 5mil LED's can run on both sources of power. The micro LED's can only run on 4.5v batteries for the moment.

This is a lengthy post so if you would like to read more please click on the Read More link below.

All the equipment I needed - not shown is a resistor.
List of Items:- (used in this section of the model)
A length of micro LEDS. These come in 50, 100, 200, 400 & 600 (running on battery). There are strings of led's in the 1000's but they run on electricity and cost more. Although saying this it does not matter what length I get as they are only going to be cut up anyway. I have noticed that the colour of LED I use will change the effect I will get when I place the decoration on the top of it. There are many LED light colours to choose from.

One interesting point is that I have used blue Christmas lights in my Shadow House and unfortunately, they have a small amount of heat and so I have had to put air vents into the decoration to let it out. I do not have this problem with the String Lights.
  1. A string of LED lights comes either in copper or silver wire (does not matter which) as long as it has the number of lights I want to use. In my case I am using 17 on the board I am talking about at the moment. All up there will be 51 lights used on the 4 boards that these particular decorations "Plants" will be placed on. These come in a range of colours but I chose Bright White. I explain how I did this much further down the post.
  2. 1 x 5mil LED (In any colour it does not matter, it is only for when using the 1.5v or 9v battery to check the lights are working BEFORE being soldered).
  3. Resistor - I use two - One is 430 Ohms (to be used with the 5mil LED) and one is 15 Ohms. I took a string of 200, 100 lights apart and it was a 15 Ohms resistor inside.
  4. Soldering Iron and holder (the spiral contraption in photo)
  5. Solder - I use 60% tin & 40% lead.
  6. Wire Strippers (the red pliers)
  7. Extra Arms (I think they are called) They hold the wires in place when soldering.
  8. Battery pack that will hold 3 x AA Batteries. I could not find one that only held 3 batteries so I am using a pack that holds 4 x AA and I will tell you what I did with it later.
  9. 1 x 9v battery to check lights are working before soldering.
  10. 3 x 1.5v AA batteries
  11. An on/off switch - I have used a small bedside lamp switch (if I want to keep the switch hidden inside the model) but will (from now on) be using an SPST - Round Actuator (Black Rocker Switch) so I can make the wiring look more professional and have the switch on the outside to make it easier to use at shows.
  12. Heat shrink tubing in 3.5 to 10mil. I like to use transparent so that I can see exactly what I have done and where the resistor is. I could use whatever colour I want but find, for me, this works. It is VERY important to use heat shrink tubing to stop the wires from touching each other and shorting out which could lead to the LED's blowing up. I like to pre-cut the tubing into 2cm lengths for the number of connections I will have to cover before I start.
  13. Wire - I use stranded 0.12mm wire in black (as negative) and white (as positive). I can use any colour combination I like, there is no difference to the wire but, again, this suits me. I like to use the same colours throughout the whole model otherwise it starts to get real confusing.
  14.  Scissors.
  15. Sandpaper or craft knife for scraping off the transparent coating on copper or silver wire of String LED's.
  16. A piece of ribbon approx 20cm long for the battery pack. This will sit at the back of the batteries and make it so much easier to remove the batteries when required.
  17. Decoration to put over the top of the lights. In my case I am using something I made in 2009 but never found a place to put them, now I have (2016). They are made of Selly's Glass Silicone (because it is non-toxic - it is used to seal up fish tanks) and is semi- translucent. I squeezed it into water bomb balloons with a silicone gun, put a balloon clip on the end and left to dry.
Started with working out the number of mircro LED's and tops needed.

First - Once I knew what section of my model I was working on and decided to use these silicone 'plants' I then gathered them into four bundles of 2 x 3 plants and 2 x 5 plants. I will eventually have four sections of my model with 51 of them glued in place.

I then cut the micro wire so that I had the required number of lights for the number of 'plants.' *There is a beginning and an end with these lights. The power ONLY goes ONE WAY. I cut IN-BETWEEN the lights so that I had a decent length of copper wire to solder onto on each end of the light. Note that the very end of the string of lights will have no spare wire past it as it does not need to as the power is not going beyond it.
This shows where the battery pack will be located which is the left end of the board.

Second - I decided to put the battery pack at the end of the long board so I could reach it easily. This section of the model was added many years ago because the new wood, that I used over 20 years ago, surrounding each section had shrunk and in doing so left a large gap. That gap has now grown to 20cm wide and is 80cm long!
Note, I will be changing the on/off switch (in the photo) to the round one later. It will be easier for me to use at shows.
Making of the Indicator Light
FIRST - it is VERY IMPORTANT that I NEED to be able to test which way the power is going in the lights without blowing them up. I can not just touch the end of the LED to a battery pack. The excess power will probably blow up the LED.
The solution is to solder a 430 Ohms resistor to one wire, does not matter which, negative (black) or positive (white). Then solder the 5mil LED to both wires making sure that the resistor is soldered to the LED (see photo below). Make sure that the negative wire (black) is on the negative leg of the LED and the positive wire (white) on the positive side of the LED or else it will give an incorrect reading and the whole process will become very complicated.  It is VERY important to remember to put heat shrink tubing over each leg to prevent the two legs from touching each other when attached to the 1.5v or 9v battery. If they touch then the cross-over current (short circuit) could explode the LED.  See finished light below.
Completed 5mil LED with 480 Ohms resistor protected with transparent heat shrink tubing.
There are four ways to tell you what side of the LED is negative.
1. First - inside the LED the larger of the elements is the negative side.
2. Second - The negative side of the LED is flat. The positive side is round.
3. Third. - There is a ridge around the base of the LED. On the the flat side the ridge is missing.
4. Fourth - The 'legs' of the LED are different lengths. The negative leg is shorter than the positive side. Although there are times when it is very difficult to tell, that is when the other indicators come in handy.
This is how 3 to 5mil LED's look internally and how I add a 430 Ohms to them to protect them.
Next, I twisted a second set of wires to the wires with the light. Black on black and white on white. One end of the second set of wires will be used with the 1.5v or 9v battery when I need power.  The other end will be used to attach to the string of lights. I have now produced my Indicator Light.

Indicator Light lit up
Indicator Light not lit up
To test the String of Lights it is MOST IMPORTANT that a small section (approx. 3 to 5mils in length) of the transparent fine coating on the copper (silver?) wire is scraped off by either a knife or a piece of sandpaper or else the electrical current CAN NOT get through the coating and WILL NOT work. *I do not worry if I do not get all of it off as long as I can get most of it off. I am just trying to get enough of the surface area free so I can solder the wires together.

So now I have the Indicator Light set up I can twist (do not solder yet) the extra two wires that were added later to any length of String of Lights. It does not matter it if is the every end of those single wires or the double twisted wire (with the light). One the wire is twisted onto the end of the string of lights and by just touching the top of the 1.5v or 9v battery - negative to negative (black wire) and positive to positive (white wire) - I will know which side of the string is negative and which is positive. If I found that the Indicator Light lights up but the String of Lights does not then I would need to alternate the wires on to the other legs of the string of lights. If they still don't light up I would turn the lights upside down and try the other ends. If they still do not light up I would scrape the wire a bit more to help make a better contact. I would continue this process until they do light.  It is important that both sets of lights are working or else it will become VERY complicated as more lights are added.

Setting up the Wiring - in this section of my model.
If I was going to light up the whole string of say 100 or 600 lights I need to do nothing (unless I wanted to change the on/off switch) except add the decoration on the top (see image below). The string comes with its own battery pack.

So let's start.  It is important to keep in mind the type of decoration I want to use on top of the light. It's size and number of them.

Next, I need to choose where the lights are going to go. For me, it was this section of board - see below. I had made a frame of wood and then filled it with chunks of polystyrene. I then stuck cardboard underneath (this is necessary to stop the battery pack from falling out through the bottom) and then carpet underlay on top of that so that the base would not scratch any furniture. I then covered the top of the polystyrene with faux sheep's wool and started decorating it. See below.
Working out placement of "plants" and therefore the lights.
  • Once I had chosen the colour of the light (Bright White - see further in the post as to how I did this) I cut it up into sections of odd numbers. Remember that I cut it in the middle of two lights so I would end up with roughly equal length copper wires on both sections. I ended up with two sections of five lights and two sections of three lights. Note that the very end of the string of lights does not have an extra length of wire on its end as it does not need it because the power ends there.
  • Next, I scraped all the ends of the copper wire so I could solder them later. It is VERY important to remove the clear coating that is preventing the wires from short-circuiting when they touch otherwise power can not go through them and the lights will not light up.
  • I cut suitable lengths of black and white wire required to go in-between the sets of lights. They differed in length depending on the distance between each set of lights. I stripped the ends of the wires for about 5 to 10mil's and twisted each the end (not together). This was so I could twist all the wires onto the strings of lights later before soldering to make sure that they are all working.
  • Using the two wires on the Indicator Light that have nothing attached I twisted the lengths of the sections of the lights, one at a time, to check that I had the lights facing in the correct direction.  I attached the black wire to one leg and the white wire to the other. I knew if it is working because the Indicator Light would light up and the string of lights would light up. I prefer to start at the end of the eventual string of lights as I like to add the 15 Ohms resistor onto the very last negative line of wire just before it gets attached to the light switch and battery. This way I can see that the resistor is there when I look at the battery pack and toggle switch. If it was hidden amongst the model and its lights, my head (being a sieve) would forget and wonder and upset me. This way I have negated that problem.
  • Once the LED's lights up, I remove ONE LEG (of the string of lights) AT A TIME and twist on a corresponding new piece of wire. I.e. Undo a negative leg then twist a new negative wire to that leg. I then do the same with the positive. MOST IMPORTANT - I slide two pieces of heat shrink tubing onto each wire BEFORE I wire the sections together. If I did not I would have to undo everything to get them in place. I allow them to slide around and DO NOT HEAT THEM IN PLACE YET.  I keep doing this until all the strings of lights are running in the same direction. I ALWAYS USE THE INDICATOR LIGHT to protect the String of Lights when checking that the all the lights, as I am adding them on, light light up. When I have the lights in place and they are all working I then add a length of wire to the very last light and just before the wire gets added to the battery pack I add its own 15 Ohms resistor. Once it has its own resistor it will not need the Indicator Light to protect it. 
It is MOST IMPORTANT that 3 to 5mil of the transparent coating on the wire is scraped off, or use fine sand paper, to remove it. This coating is stopping the wires from shorting out by touching each other. If it is not removed it is impossible to solder them together and the power WILL NOT travel through the wire.

    Heat shrink tubing in place before it has been heated up using
    the soldering iron.
  • I then start soldering it all together. It seems to not matter which side of the LED I put the resistor. I was going to add a video of how to solder but they go for soo long I figure it would be easier if any of you wanted to know how to solder stranded wire to look on YouTube also how to solder a resistor to the end of the stranded wire.
Now I have the soldered wire I can now slide the heat shrink tubing into place (over the solder) and using the heat of the soldering iron touch the heat shrink tubing and move the iron around until the tubing has shrunk tight around the solder.
This is how the finished wiring shall look
 (except for me I have now changed the on/off switch)

Fixing the ON/OFF switch and Battery Pack.
At the beginning, I choose what is called a Lamp Switch (see right). The idea is that the positive wire is cut in half and the switch inserted in-between the two pieces of wire making a link. So when you press down the link is either on or off. Fortunately for me when I went back to Jaycar to buy more Lamp Switches they had sold them all. So what to do? I ended up with the round black toggle switch that can be added onto the outside of the model and now it looks much more professional. I am WELL PLEASED.

    I am now using this type of rocket switch.
Two rocker switches in place. Note the heat shrink tubing on the positive wires and connections. Also because I had two sets of wire note that one set has a piece of yellow tubing on it. This lets me know which set of wire belongs to which on/off switch.
This is what the toggle switches look like. I just have to fix the faux sheeps wool around them to make them look neat.
  • I have used a faux sheep's wool as the "grass" and have gone over the top of the model with the wiring and will need to camouflage it.
  • On another section of the model I have actually gone under the "grass" and brought the lights up through a hole so I do not have to cover the wire with decorations. I will add another post on that as it is more complicated to do than this one.
Working out the correct Colour Light I wanted:-
  • The next thing I needed to work out was what colour light I wanted to use. I already knew I wanted a Bright White. So using the Indicator Light (because of the resistor) I placed a decoration over the top of the coloured light to see the effect.  When I made the lights for the model below (see photo) it has a jumble of different coloured plastic grapes (decorated in a variety of ways) on top of the lights. Note how the colours differ. Also because I was not using (at the moment) the correct resistor the amount of light shining through the decoration will not be the correct amount of light but it did give me, however, an indication of what it would look like.
  • The image to the right shows how two different colour lights, pink and purple break up the solid wall of light.
Battery Pack:-
Because I need to run the String of Lights on 4.5v batteries I needed a battery pack that would hold three x 1.5v batteries. Even though these lights come with such a thing I have not worked out how to change the switch they have and because I want to use the black round toggle on/off switch on the outside of the model the switch on the battery pack does not fit the job. So because I could only find a pack that holds four 1.5v batteries I have done this:-
  • I purchased a battery pack that held four 1.5v batteries.
  • I got a small piece of stranded wire. I chose white just so I could see it against the black of the battery pack.
  • I also needed a large piece of transparent heat shrink tubing. 1cm x .5 to 1cm wide tubing depending on what you can get. The larger the better.
  • I strip of 20cm of thin ribbon.
First cut the white stranded wire (1.5 to 2cm) longer than the internal section of the battery pack.
  • I stripped off each end and twisted each end separately. I did NOT join them together.
  • In the battery pack, there is a spiral of wire. One end of the wire needs to be twisted onto the top end of the spiral. I just slid one end in and brought the loop up over the end of the spiral and then twisted the clean wire together to hold it in place.
  • I then soldered that in place.
  • I then slid the small piece of wide transparent tubing over the wire and the end of the spiral and heat shrank it in place using the soldering iron.

See the metal spiral at the base and the round metal hole at the top.
  • I then stuck the rest of stranded wire up the hole at the other end (making sure I had slid a thin piece of transparent tubing onto it first.
  • It is important that the wire touches the metal circle. I made sure that there was no plastic in contact with the metal circle or else the power will not flow through it.
  • Before the wire is soldered in place I put the ribbon around the battery pack. I put the batteries in the pack (keeping the ribbon at the back of the batteries) and using the Indicator Light I checked that the light lit up. If it does not (and knowing that the batteries are not flat as I checked them using a multimeter) I moved the wire around making sure I got a good connection against the metal circle. Once I got that connection and the light lit up I then soldered the wire in place.
Finished Battery pack
Joining the Lights to the Battery Pack.
So finally I have everything in place and all I have to do is join it together. Now I like to have enough wire attached to the battery pack that I can comfortably take it out of the place it lives in and change the batteries when required.
All that needs to be done is to add the 15 Ohms resistor to the battery wire (negative or positive it seems to not matter). I then join the wires from the battery pack to the wires of the display.

  • It is always important to remember to slide on a piece of the transparent heat shrink tubing onto the wires before soldering. If I forget, which has happened, I have to unsolder everything and fix it.
Now if everything has worked I should be able to press my toggle switch and whoola - light!
Ignore the type of switch I have here. This image is just to show you the lights should look before decorating.
Decorating Lights:-
There are 1000's of ways to decorate these lights. For this board I am using the "plants" I made in 2009 and it is now 2016. I love the way these "plants" look like and had always seen them with lights. In the beginning, I used rice bulbs, well they were a disaster due to the heat they generated and the amount of power they used. Finally, though I have found the perfect place to put them - onto four of the seven board that make up Pebble Cottage.
  • So first it is necessary to glue them in place. I do not usually use a white silicone but it is what I had on hand. Even though it was non-acid I will not be using it again. For one thing, it did not dry clear as the container said it would and for the second it took days to dry.
I found that surrounding the "plants" with masking tape helped to hold them
together until they dried. Those squilly bits in-between are fake grass. It has
helped hide the excess silicone.

The bunny tails (dried grass) was the original decoration on the board. Once the "plants" had dried on the board then I was able to decorate the entire section to cover the wire.

This is not finished being covered yet but I love the overall effect. I have used a multitude of items to give the effect of plants. I am VERY pleased with it.

The end. Thank you for visiting My World.

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