setting up something for halloween, i need a set of xmas lights with only five bulbs burning, so i took an old set of lights(it had 15 lights to begin with) and cut the first four bulbs and the very last bulb from the string added 5 foot of wire between them soldered and covered the exposed wire with black tape went to plug it in and blew the fuses (3A) went and rechecked each connection point, replaced fuses and bulbs and same thing happened what else can i do to make it work?
custom christmas light string
Oct 14, 2011
7 Replies
blackbeard schrieb:
Hello,
if you don't know how these xmas lights work and how they are connected, you should not change anything.
The bulbs of these xmas lights are connected in series, 15 times 8 volts make 120 V together. If you remove 5 bulbs, you should connect the remainig 10 bulbs only to a 80 V source, but not to a 120 V source. Adding 5 foot of wire does not change anything, because the resistance of the wire is much lower than the resistance of five bulbs together.
If you want to operate 10 bulbs connected in series on a 120 V source, you would need bulbs with 10 V each. Of course all bulbs should have the same resistance and power consumption.
Don't try to use a resistor instead of the five bulbs, using the wrong resistor would result in a very hot resistor and could ignite a fire.
Bye
Put a diode in series and the average voltage will be about 60 Vrms.
tm
No, it won't. 120 * .707 = 84.84 minus the diode drop.
You can't have a sense of humor, if you have no sense.
Transformer
That original string had a wattage rating, so now you need to add a series load to bring the total wattage back up. The 5-bulb string is obviously working at 1/3 the original wattage. The series load can be a power resistor or another single bulb or the remnants of the original string bundled up and placed out of sight..
I was thinking the same.........
An easier way is to use 12volt Xmas bulbs. They are often used in tree tops such as stars. They are a string of 10 bulbs (10 bulbs X
12v = 120v). Then just cut 5 sockets with the bulbs from the string, and wire them in PARALLEL to a 12volt source such as a car battery or a wall wart transformer. Always use a fuse for safety.Years ago I designed a reindeer with animated (moving) legs for in the rear window of my car. I used all 12v bulbs, soldered each socket individually. The animation was done with relays which lit different leg positions, and was driven by a tiny motor with contact switches on a cam. This was the original design, I had intended to design all electronic switching, but I never did. The reason I never changed it, was because it worked great, the problem was that the police were constantly pulling me over. Never got a ticket, most of the cops just wanted to see it up close, and would even compliment me for it. But one of them did make me shut it off and said if he saw it on again while my car was moving, he would ticket me, I think his name was Officer SCROOGE.
The other problem with the design was that there were around 150 bulbs and my car alternator could not keep up with the load, particularly since the car heater was also in use at that time of year. I had to keep a spare battery (charged), in case the car did not start when I was not home, and as soon as I'd get home, I'd connect a battery charger.
I have to admit, I had a blast doing this, and back then I got really carried away with x-mas decorations. The yard decorations were all connected to remote controls and body sensors. It would take weeks to set it all up, and after xmas the electric bill was shocking.
These days they have these computerized xmas displays run by music. They have far surpassed what I did back then, but that was in the
1970's and 80's before all this hi-technology stuff. These days I dont decorate at all, I just drive around and see what other people do, and there is a park an hour from my home that has over 2 million lights, with hundreds of animations. I was told they require 1000amps of power to run that display. I'm hate to pay that electric bill..... (they are switching all the lights to LED types though).
O = 12v bulbs from tree topper
.---O---. | | |---O---| | | |---O---| | | |---O---| | | |---O---| | | | | + 12vdc -
Power from 12v battery, wall wart, or other power supply. Both AC or DC will work.
Or use 6v xmas bulbs and one of these batteries.
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Replacement xmas bulbs in packages usually show the voltage on the package.
If you really want to get fancy, use LEDs and one of these batteries. Batt will last much longer. Be sure to use a suitable resistor on each LED.
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