Wednesday, September 11, 2013

How to light up your tanks!

(Sorry for taking so long posting this I had this half written last week but it's just crazy around hear right now and I don't have as much time to do this stuff as I used to. At some point soon I will have more time for the blog again)

OK I am not sure how is best to present this so I am going to start off with how to set up a LED circuit then I will try to show how I mounted my lights in my rhino.

when you are setting up your lights you need to look at what you want light wise and what parts you can get as there is no pre set voltage all LED's need and if you don't know you cant order the rest of what you need.
so for the example I am using I will be using two 3mm White LED that uses 3.4V and two 3mm flashing red LED uses 3V at 20ma  we should also look as how we want to power this and seeing it is a cheep hobby project one nine volt battery should do (nice 9v connectors are cheep)  the only down side is that in choosing this supply you have to make sure you are running in parallel not in series.
if you hook them up in series you have to add up the voltage from each LED and sense we have four that take up three volts or more they would need a 12V or greater power supply.

 But by hooking them up in parallel they each get the full 9v from our battery.  
any way now that we know our power supply will work and we know what we are powering we can start on our Ohm's law equation...   Behold the mighty Ohm's triangle!! with it we can balance out our circuit and find out what our missing piece is

OK we know we are useing a 9v power supply and we are using LED's that need 3v or so at max. To make sure we don't shorten there life lets run them with 2.5v that should make sure they never burn out in our carefully painted modal. so 9-2.5= 6.5 so we need a resister that will eat up 6.5V 

and we know we want to have a flow of 20ma to the led's from the battery so we need to see how much we need to resist the flow
Now we do the division and get 325

so we know we need a resistor of 325 or slightly better these are 330 and will do just fine

(NOTE: if you don't want to do any of the above calculations there is an app you your phone called ElecrtoDroid and it has an LED resistor calculator you can just punch your numbers into. But I would jump what ever it says up a bit as it is giving you the absolutist minimum resister you can get away with if you want your LED to last go up one or 2 standard resister sizes to make it last)

    last but certainly not least we need a way to control this little circuit. you could just disconnect the battery when you don't want the lights on but who wants to do that when you can hide a nice little switch some where and make your set up a little more slick. I like These dip switches they are easy to hide  you will also need a bit of wire this works and a place to hook everything into is also help full I like these and you can trim them after you build your circuit later  I suppose it bares mentioning that you need a soldering iron get something with higher wattage it is only a few dollars more then the low wattage ones and will work better for you if you want to keep doing this kinda thing.
you also need solder  thin is better you are making small connections so if you want any control you only want a small amount flowing into you're connection at a time.

Now you have a small pile of junk lets turn it into something useful for you 

first set your switch into the back of the board then add in the 2 resistors set them so that one end connects to each switch and the other is off set to a different row to make it easier to solder the wires to them.

Next solder the connection for the resistors that connect to the switch and also solder the red positive wire from your 9v snap connecter across both of the other connectors for the switch.

  Now its time to add some wire to your LED's the length of witch will be determined by where you are using them for a Rhino  4.5 - 5 inches works well if you wanted to get them down to the end of say a Valkyrie wing you will need more just look at where you want to mount your switch board and how far it is from where you are mounting your LED's  you should also note that the longer bit of wire of an LED is always the positive side so keep the wires the same as the rest of your positive wires (red normally) it just keeps things simple that way.

Well this came out a bit blurry but the idea is that you need to clip the LED leads short so that you can both keep them from touching and let them flex when installed in your tank or plane or what ever you are adding them into. 
seance this is one of the shots that actually shows the solder fairly well it will be a descent example of what your solder connections should look like they should be shiny and smooth if they are lumpy you added to much solder and if they are gray and rough them you got a cold joint and should remelt it to ensure they make a good connection. If you added to much solder you will need either Desoldering braid or Vacuum Desoldering tool. I use the braid because well that is what I have on hand but basically you just lay the braid over the joint that you wish to remove solder from and press the soldering iron onto the top of the braid and it will wick the solder into the braid and away from where it is currently 

Bam! all four done

I am placing my LED's together seance that is how they fit into the headlight bracket so I have the chance to save some space and wire by soldering the negative wire to both LED's at one time and it has the bonus of making them form a nice solid line and less likely to touch each other and short out if there is any chance your wires will touch make sure to glue the wire down to keep it from moving or add some heat shrink tubeing

hear is both set of wires finished and blurry as hell.....

 find your self a good place to connect all the negative wires together you don't even have to add them to the perm board technically but I find that it keep's things cleaner if they are all in one place.
I poked all three threw the board in a row then placed them down across each other and soldered them all in the line you see above.

 The next step is to connect all the positive wires from the same color LED's to each of the two sides of the resistor leads that are left currently unsolder-ed  this one I believe is the 2 white lights
now repeat with the red blinking ones on the bottom with the last resistor lead  make sure both of the red wires from them connect cleanly and wile you are at it check all the other connections to ensure nothing is touching that should not be. if you don't you might have a short that could fry your battery or your LED's or both.
All finished

yep the white LED's work fine

and so do the red ones

     Now its just one to normal modeling stuff that your guys are all ready good at I wish I had something to install it in as an example but I lack  anything that would work so hear is some shots of my completed rhino  that should give you some ideas on mounting the switches and lights




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