LED Christmas tree

[RepairingDave]

I have got a what could be described as a "150cm led globe tree w/200 static ice white leds rs01385" Christmas tree.

Unfortunately, I was given this tree, but no power adapter was with it.
From the labels it needs a DB-12-24 adaptor, these are for sale for prices around £20 or there are cheaper ones on eBay.
I am wondering how to test to test it without paying for a new adapter:
-> I can test the resistance (continuity), but will this guarantee it will work when it has power?
-> what would happen if I used a different adapter? I have adapters with 18 and 19 volt output, but none with 24v

The tree is currently in a loft, so not easy to get to.
Photos of label attached.

 

[Harry Bloomfield]

-> I can test the resistance (continuity), but will this guarantee it will work when it has power?
-> what would happen if I used a different adapter? I have adapters with 18 and 19 volt output, but none with 24v

Two car batteries, wired in series?

It requires 24v 12va which is near as matters 12watts. So a power supply of 24v 0.5amps. It is not clear whether it needs to be AC or DC, but probably DC.

 

[SUNRAY]

Two car batteries, wired in series?

It requires 24v 12va which is near as matters 12watts. So a power supply of 24v 0.5amps. It is not clear whether it needs to be AC or DC, but probably DC.

That'll be AC then

 

[Harry Bloomfield]

View attachment 360769That'll be AC then

Missed that, OP - it requires AC.

 

[Harry Bloomfield]

Missed that, OP - it requires AC.

Even more awkward then.. You could find a pair of matched 12v transformers, able to deliver 0.5amp, and wire their outputs in phase, and in series, unless you could find a 24v one. AC, will mean an old-fashioned, wound transformer.

 

[Harry Bloomfield]

Even more awkward then.. You could find a pair of matched 12v transformers, able to deliver 0.5amp, and wire their outputs in phase, and in series, unless you could find a 24v one. AC, will mean an old-fashioned, wound transformer.

Giving this a bit more thought...

I would hazard a guess, that those LED's are just mounted back to back, in pairs. One LED lights on half the AC cycle, the other, on the opposite half cycle. In which case, you should be able to get enough light to test one half of them, with a 12v battery, then reverse the battery connections, to test the other half.

 

[RepairingDave]

Giving this a bit more thought...

I would hazard a guess, that those LED's are just mounted back to back, in pairs. One LED lights on half the AC cycle, the other, on the opposite half cycle. In which case, you should be able to get enough light to test one half of them, with a 12v battery, then reverse the battery connections, to test the other half.

I'll give it a go next time I am up the loft.
I haven't got a 12v battery, but I have adapters with a 12v output which should do the job.

 

[SUNRAY]

Giving this a bit more thought...

I would hazard a guess, that those LED's are just mounted back to back, in pairs. One LED lights on half the AC cycle, the other, on the opposite half cycle. In which case, you should be able to get enough light to test one half of them, with a 12v battery, then reverse the battery connections, to test the other half.

Chances are there are 8 3V LEDS in series per chain and LEDs may require 3V to strike so something near the full 24V will typically be required to do any sort of testing (I have a dozen or more 50m 500LED sets used for stage decoration and have employed a selection of methods to run them, they require a minimum of 29V to even think about lighting)

 

[SUNRAY]

Ah the thot plickens...
A google search comes up with several variations of a DB 12 24 power supply. 2 are straight forward transformers and one is an electronic sequencer.
Looking at the pics again I see there is a join:

The arrows point to 2 seperate parts, can we see a wider image to identify what those are please2 you have please.

Is there any form of moving part involved, driven by a motor for example?

 

[RepairingDave]

Ah the thot plickens...
A google search comes up with several variations of a DB 12 24 power supply. 2 are straight forward transformers and one is an electronic sequencer.
Looking at the pics again I see there is a join: View attachment 360775
The arrows point to 2 seperate parts, can we see a wider image to identify what those are please2 you have please.

Is there any form of moving part involved, driven by a motor for example?

The part to the right is a extender/splitter - It was a easy way to see what size the plug is.
No moving parts.

 

[Harry Bloomfield]

Is there any form of moving part involved, driven by a motor for example?

I expect, they must feed it with DC of one polarity, to get one set of LED's lit, Then reverse the polarity to get the alternate set lit.

 

[SUNRAY]

I expect, they must feed it with DC of one polarity, to get one set of LED's lit, Then reverse the polarity to get the alternate set lit.

At this point we don't know what the system is, other than 200LEDs: It may be static

A google search comes up with several variations of a DB 12 24 power supply. 2 are straight forward transformers

Or capable of sequencing

and one is an electronic sequencer.

I have sets with both options.

I have some static lights with a bridge rectifier built into the right angle plug in which case it matters not if AC or DC adapter is used.

If it had a motor, chances are it would be synchronous requiring AC but that aspect has been ruled out.

 

[FrodoOne]

The way in which these LED "strings" (usually) work is
the LEDs are connected in series in "short strings" (together with a suitable "limiting" resistor)
so that each "short string" operates on the applied voltage
with the other "short strings" connected in parallel
across the applied voltage.

However, since LEDs operate on DC,
half the "short strings" are connected in reverse parallel to the other half of the "short strings".
Hence, when AC is applied, all of the strings appear to glow
BUT
each "half" glows only during one "half-cycle".

Since there is some "afterglow" of the LEDs
and
the Human Eye has "Persistence of Vision",
all lamps appear to glow continuously - with such a set-up.

So, if you apply an AC voltage slightly lower than 24 V, all LEDs should glow,
albeit not as brightly as if you applied the full 24V AC.

(Warning: If you apply DC, half the strings will glow
BUT
it may be that those LEDs are then "overdriven",
since each "string" is designed to be energized for only half the time.

However, (half-cycle) rectified AC should be OK.)


The "effects" produced by the "controllers" often use by these LED "strings"
are obtained by pulse-width modulization
of high frequency DC (and "reversed" DC) pulses.

 

[Harry Bloomfield]

(Warning: If you apply DC, half the strings will glow
BUT
it may be that those LEDs are then "overdriven",
since each "string" is designed to be energized for only half the time.

Exactly, and why my final suggestion was - to try it with a 12v battery, or 12v DC power supply, as they are much more common these days..

 

[SUNRAY]

Exactly, and why my final suggestion was - to try it with a 12v battery, or 12v DC power supply, as they are much more common these days..

Except 12V is unlikely to light a string of LEDs designed for 24V.