Making shorter light strings

[Doug-in-the-woods]

Been contemplating my candy canes with 5 channels per cane.
Looked at canes and decided that I need either bigger canes or fewer lights per channel. Opting for fewer lights.
I estimate to get 5 channels per cane I need 20 lights per string.
Either lower the supply voltage to the SSR's using a transformer but finding a large enought transformer to handle 50 volts at aprox 5?amps. 12 canes each with 20 lights per channel x 12. 2 ohms per bulb at 50 volts = 1.25 amps? dosn't sound right??
Maybe instead of a transformer put a C7 bulb in series with the 20 bulbs?
??????????
Any suggestions will help

[P. Short]

What bulbs are you using? Measuring resistance when the bulbs are cold (if that's what you did) doesn't give useful numbers.

--

Phil

[Doug-in-the-woods]

Looking at using 50 light bulb string sets cut to 20 bulbs
need 60 sets for my candy canes
Now i'm lost
went over to planetchristmas and found a chart that says a string of 50draws .17 amps
.17 divided by 50 = .0034 amps per bulb
.0034 x 20 = .06 amps
120 divied by 50 = 2.4 volts per bulb
2.4 x 20 = 48 volts at .06 amps
.06 amps x 60 channels = just under 4 amps at 48 volts
Thinking about just putting a C7 bulb in series and forget the transformer??

[Warlock]

Or you can use a copy of the article I gave Ernie a while back where they drop the voltage to 12 volts to make it safer(their reasoning) and this place I got the article from does the winter festival of Lights in Niagra Falls.If you use this method then you do not have to drop the supply voltage for every ssr.You simply drop the supply voltage for yuor controller then the voltage down the line will also be dropped as you have nothing inline to raise it up.Simply the way that display is done.I can give you a copy of the article if you wish...Let me know...

[Doug-in-the-woods]

The controller (Olson 595) has 12v for supply but I need to control the supply to 15 SSR's only.
After rethinking this I am going to try and put a C7 or C9 in series with the supply going to the 15 SSR's then the voltage should be ??(able to run a 20 light string of minis) but each SSR would control 4 strings each ?
I need to work out the math etc.

[Warlock]

Hey Doug are you using Seans SSR design or something else ??? If something else what design are you using ??

[P. Short]

Doug wants to use 1200 lights (12 canes * 5 strings * 20 lights/string). Each light takes about 2.4-2.5V, so if they are powered with 12V. The strings would now have to be 5 lights long, so there would be 240 of these 12-V strings. At .16A each (regular mini-lights), that would come out to about 40A at 12V. I'm not sure how easy that is going to be to deal with.

--

Phil

[Warlock]

Phil I was simply refering to an article that a company wrote in a mag called Professional Lighting and Production.The company I'm refering to is called Blanchere Illumination (website addy is http://www.blanchere-illumination.com) they continually use 12 or 24 volt systems to do the Niagra Falls festival of lights and have been for the past 4 years.If the switch to leds was done then the 12 volt system would work flawlessly.Mini lights does present it's own problems as we all know from past experence.I was simply suggesting he look into the possiblities of a 12 volt system as an alternative and an idea.I totally understand the math you have presented and appreciate the corrections you made for me.Math is not my strongest point especially in electronics.But the fact still does remain that the voltage can be played with as long as the triacs see the required spec voltage to operate.After that you can basically do as you please voltage wise which leaves open the possiblities of lots of tricks to use.Which was basically my point.There is also a way you can use different parts in the controllers and use a lower voltage as well instead of the 120 volts.Just something to think about and maybe even play with...

[NogginBoink]

Doug,

For your particular situation, I think the best solution would be to buy 35-light strings that are commercially available.

[Doug-in-the-woods]

I tried wrapping a 35 light set on but it won't work by the time I get all 175 wrapped on.
I tried wiring a C7 in series with 20 3.4 bulbs (part of a 35 light set).
The C7 lite up but not full brightness and the minis didn't even have a glow..
doubled checked the wiring and all ok.
back to the drawing board
thinking about using C7 for voltage divider? Also the canes have 8V bulbs in them currently as purchased. THINKING????

[P. Short]

The resistance of an incandescent bulb varies all over the map as it goes from cool to hot, so it is not easy to use it as a voltage divider.

--

Phil

[Warlock]

What about using a resistor in the line to simulate the wattage of a bulb ???At least it will be more predictable then using a C7.....

[Warlock]

I was also just thinking of a solution for this as well...I just remembered the problem last year alot of people were having with leds and getting them to work with the triacs.They used a terminator device.I was wondering if that would work in this case as well seeing as you want to simulate a lower voltage ???

[Doug-in-the-woods]

going to cut out large candy canes from some OSB I have then paint.
4 ft tall canes with 50 bulb light strings x 5 per cane = 250 lights per cane x 12 = 3000 lights just for the candy canes. I sure hope I have enough red ones. I know I have plenty of clear ones.

[Doug-in-the-woods]

I gave up with lowering the voltage so I drew out a sketch using SKETCH-UP and came up with 12 canes 38" tall 4 inches wide 13 on one sheet of 4x8 OSB
will cut out using router later today or tomorrow. Still need to assemble that Renard 64 and Ren-T boards.
Lots to do this coming week before going on vacation in Vancouver Washington on the 11 - 25th.Still got lights to go up.
Egads I is running outta time.

[AI]

Doug; You could try a diode in series with the lights it will drop hafe the voltage but may introduce 60 hz flicker like the 1/2 wave LED lights. AI

[NogginBoink]

That's a workable idea.

Two diodes in parallel in opposite directions would give the same voltage drop without the flicker.

[fcky529]

Doug,

For your particular situation, I think the best solution would be to buy 35-light strings that are commercially available.

Use the 35 strand and black tape over the unused/unwanted bulbs to make it simple/ easier and wrap the unused portion in foil to avoid the "dead wire" look inside.

(as long as it's cold in your area, and/or are not worried about possible meltage.

or you could always chop the unwanted part of the 35 measure the resistance of the remainder and add equivalent resistor to the end.

[Doug-in-the-woods]

Adding a LARGE resistor as the resistor would get really hot. I saw a discussion on doing this and it mentioned a 5 watt resistor or larger.

[P. Short]

Measuring the resistance of the string/bulbs is not a very useful because the resistance of incandescent bulbs varies quite a bit between hot and cold. It'd be better to measure (or look up) the current and use that to calculate the value of the resistor.

--

Phil

[jeffathompson]

"I tried wiring a C7 in series with 20 3.4 bulbs (part of a 35 light set)."

This is a electricians question, not an electronics calculation and I think I can answer that. You put 1 C7 bulb in series with anything and the C7 draws all of the 110 volts. It will share the 110 with however many mini bulbs you put in series with it. Either a transformer to reduce your votage or a resister to reduce it is the only real option. I'd have to do the math but you can probably do a web search for the correct resitance. The real question is if you are running 4 strings off one ssr, why don't you just put 2 20 bulb strings in series. Another option is to use a dimmer switch but that's a lot of $2 dimmers on that many canes.

[cruizer]

Have you looked for 20 light strings? I bought half a doen this year for my display.