Powering Big W strings

Habbosrus

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Hi All,
Please help. I have some Big W strings that I am hoping to incorporate into my very first light show this year. I am trying to understand powering options. I was thinking 24v dc but then started to doubt myself. Best thing to do is ask those who know. I have attached a photo of the transformer details.
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David_AVD

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You'll need a DC power supply in the range of 28V to 31V to run big W strings. 24V DC is too low to run them.

I use a Mean Well SP-240-30 (30V but adjustable) for the Big W strings in my display.
 

Habbosrus

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Thanks David. It sure pays to check with those who know. I was originally looking at something around the 30v range after reading through the ACL forums a couple of months ago. Then I think I got myself all confused after reading some stuff recently on DIYC.
Steve
 

battle79

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You can run them off 24V as that is what the original transformer and bridge rectifier do......

BUT you can run them at 30V due to the LEDs being able to handle it easily. And best of all they are much brighter at 30V.

Cheers,
Rowan
 

aussiexmas

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battle79 said:
You can run them off 24V as that is what the original transformer and bridge rectifier do......

BUT you can run them at 30V due to the LEDs being able to handle it easily. And best of all they are much brighter at 30V.

Cheers,
Rowan
Sorry, I've got to disagree. At 24V DC, most colours will not even light up, the reds will, but the green, blue & white will not light. At about 30V DC, the brightness is about the same as when running on their original transformers and controllers. The rectifiers in the controller is not filtered and the output voltage is a rectified half sine wave. This peaks at about 34V and the light string only responds when the voltage is above its threshold level - about 27V. If you take a steady lit string powered through its original transformer and controller and swing it around, you will see that the lights are not continuously on, but are a series of "on-off" dashes.
[attachimg=1]
 

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adski

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I can confirm what Geoff and David have said - you need around 30V DC to power Big W LED strings.

Dave
 

fasteddy

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The reason being is that a 24v AC sine wave signal goes from a peak to peak voltage of around 34 volts with the RMS Voltage being 24 volts. So when using a DC power supply to directly power a BigW string we then need to up the voltage from 24 volts to around 30 to 32 volts to get the best balance of light output whilst not over driving the LEDs
 

ecbailey

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I used one of Ray's 27v Power Supply's with the adjustment turned all the way up (I think it made it around 31v) to power my Big W strings.


http://www.aliexpress.com/store/product/AC-DC-Switching-Power-Supply-with-85-to-265V-Input-Voltage-27V-350W-output-CE-approved/701799_431656111.html


The LEDs were much brighter with the 27v PSU than the original powerpack.


I found it interesting the amount of brightness difference there is between the minimum voltage and the maximum that the PSU can output.
 

Goldie

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I use 24V AC rectified, had no problems for the pass 2 years, pretty sure the rectified increases the DC voltage
 

fasteddy

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Goldie said:
I use 24V AC rectified, had no problems for the pass 2 years, pretty sure the rectified increases the DC voltage
This is why when using a switched mode DC power supply you need to run it at around 30 to 32 volts because effectively the bridge rectifier inside the BigW controller is outputing at a higher voltage than the 24vAC because of the peak volatges. So by adding in a bridge rectifier you are effectively just adding back the rectifier that was removed when the multifunction controller was removed.
 

David_AVD

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ecbailey said:
I used one of Ray's 27v Power Supply's with the adjustment turned all the way up (I think it made it around 31v) to power my Big W strings.
Something to be aware of is that sometimes the cheapy Chinese 27V power supplies are actually 24V units that have be "wound up" to 27V and stickered as 27V units. This is all well and good... until you try to increase the output to 30V and find there's no adjustment left!
 

fasteddy

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David_AVD said:
ecbailey said:
I used one of Ray's 27v Power Supply's with the adjustment turned all the way up (I think it made it around 31v) to power my Big W strings.
Something to be aware of is that sometimes the cheapy Chinese 27V power supplies are actually 24V units that have be "wound up" to 27V and stickered as 27V units. This is all well and good... until you try to increase the output to 30V and find there's no adjustment left!
Plus sometimes they will blow a capacitor if wound too high
 
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