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kenjinx
11-25-2008, 01:19 AM
Is there a way to make custom sized light stings? Say I want to have one controlled window but it only takes 25 lights to go around it. If I have a 100 light strand can I just cut off the other 75 lights? I know this will change the resistance of the strand. Is there a formula to find the least amount of lights on a strand before the bulbs blow?

joneslights
11-25-2008, 01:22 AM
Is there a way to make custom sized light stings? Say I want to have one controlled window but it only takes 25 lights to go around it. If I have a 100 light strand can I just cut off the other 75 lights? I know this will change the resistance of the strand. Is there a formula to find the least amount of lights on a strand before the bulbs blow?


I believe you can only cut them in the middle (50 bulbs) 50*2.5v = 125V roughly. You could always cut them at 50 and then fold the set.

Wayne J
11-25-2008, 02:43 PM
You could just buy a short string of lights of the count you need, then just replace the bulbs in a custom length string for you needs. I know the drug stores and such sell odd number count strings for interior decorating for Christmas. So you may get lucky and find what you need (for the bulbs). I have some candy canes I bought, that run induvidually and are 20 count strings in them.

DavidHenry
11-26-2008, 09:56 PM
I'd get a string of 35, and tighten up the spacing a little bit between bulbs (not by removing wire) so that it fits.

The other thing is that strings of 30 are rare but do exist, and 35's are common. Not all will have the same lighted length. Measure the distance on the window you're trying to cover and see if you can find a string where the length that has bulbs is the closest. Not all brands are the same.

If you get lucky, it's easy.

Rocketman4
12-04-2008, 12:21 AM
If you cut the strings you must change the input voltage. If the bulbs you are using are 2.5 volts and you need only 25 bulbs first you mulitply 2.5 x 25 = 63volts. You would need a transformer that has an output voltage of a maximum voltage of 63 volts, a lower voltage would mean that they would not be as bright. You would be better off by purchasing a shorter string. I have made my own CCanes with 10 lamps each and purchased a 24v transformer. The ssr work great with the lower voltage but I would not reccomend this to anyone that is not familar with ELECTRICITY, it can cause a FIRE.

Warlock
01-01-2009, 10:38 PM
I have read that someone once used a resistor to make up the difference and confuse the other bulbs...Others have simply changed the voltage of the bulbs..Like 5 volt bulbs or 9 volt bulbs..WIth leds I have seen people do the same thing..Simply replace the resistor in the cord end of the plus..Altho the newer leds are not made this way so you can't replace the plug.What I heard (not sure if this is true or someone wants to correct me on this) but you can strip back a bit of the wire on one side of the power cord..Splice ina resistor to make up the difference and confuse the rest of the set to make it think it is drawing the same amount of power...Again not sure if this actually works but I'm trying to find out the same info..

Matt_Edwards
01-01-2009, 11:33 PM
I have read that someone once used a resistor to make up the difference and confuse the other bulbs...Others have simply changed the voltage of the bulbs..Like 5 volt bulbs or 9 volt bulbs..WIth leds I have seen people do the same thing..Simply replace the resistor in the cord end of the plus..Altho the newer leds are not made this way so you can't replace the plug.What I heard (not sure if this is true or someone wants to correct me on this) but you can strip back a bit of the wire on one side of the power cord..Splice ina resistor to make up the difference and confuse the rest of the set to make it think it is drawing the same amount of power...Again not sure if this actually works but I'm trying to find out the same info..

I do this when converting Minis to LEDs strings. Yoiu need to measure the current drawn by one string (I). the voltage per light is 120Vac ( US) divided the number of lights per string. The resistor value will be number of lights removed * the volts per light, all divided by the current per string. The power consumption in the resistor must also be considered, = Vres*Vres / I.

Cheers
Matt

Warlock
01-02-2009, 12:00 AM
Thanks Matt..Pretty much what I read about before...What about shortening a set of leds ??? Would it work out to the same way of doing it ?? Also LOR had posted the values of certain counts of light strings...For example this is what I have for a resource from LOR..Tell me if it is accurate..Thank-you.
Joe


Christmas Light Power Consumptions
The following table gives the approximate current
consumption for various types of Christmas lights.
Description Lights/string Amps/string
Mini-lights 50 0.17
Mini-lights 100 0.33
C7 bulbs 25 1.04
C9 bulbs 25 1.5
100 watt bulb 1 0.75
150 floodlight 1 1.25
LED mini-lights 70 0.03
LED C6 or C7 25 0.02
If you put six sets of 100 mini-lights on one channel,
that would be 6 * 0.33 = about 2 amps. If you put
six sets of 70 LED mini-lights on one channel, that
would be 6 * 0.03 = about 0.18 amps. You can see
that you can get a lot of LEDs with very little power.
Make a chart of all the lights you want to connect to
the controllerís channels and then work out the
numbers to see if you hit any limits.