On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

--
F

On Thu, 21 Dec 2017 11:54:50 +0000, F news@nowhere wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

It's basically just a transformer but to use one you would need to do
some wiring and put it in a suitable box etc.

4V is a bit of a funny one and the nearest I can find is:

https://www.maplin.co.uk/p/2x45v-6va...nsformer-a76qj

You can actually get 'empty' wall wart boxes that you could put said
transformer in for yourself ...

Cheers, T i m

On Thu, 21 Dec 2017 11:54:50 +0000, F wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

I should have looked at the picture more closely! I've looked and can't
see nything obvious - 4 volts AC at no more then 0.5A or so seems hard to
find.



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

On Thu, 21 Dec 2017 12:11:59 +0000, T i m wrote:

On Thu, 21 Dec 2017 11:54:50 +0000, F news@nowhere wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

It's basically just a transformer but to use one you would need to do
some wiring and put it in a suitable box etc.

4V is a bit of a funny one and the nearest I can find is:

https://www.maplin.co.uk/p/2x45v-6va...s-transformer-
a76qj

You can actually get 'empty' wall wart boxes that you could put said
transformer in for yourself ...

I found:

CPC TF01368 for the transformer

They also do wall wart boxes (I've used them to replace damaged ones),
although I can't find them right now.



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

In article ,
Bob Eager writes:
On Thu, 21 Dec 2017 11:54:50 +0000, F wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

I should have looked at the picture more closely! I've looked and can't
see nything obvious - 4 volts AC at no more then 0.5A or so seems hard to
find.

You might find the lights work fine on DC, in which case a 4.5VDC
supply would work. Test it with 3 battery cells.

I have a few things that came with low voltage AC wall warts,
but DC ones work fine. This may not always be the case though.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 21/12/2017 11:54, F wrote:
On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

Try it on 4.5v of batteries with a silicon diode in series (and a 500R
series resistor if you want oo be cautious).

My instinct is that the first thing the thing does is rectify the AC to
DC before it reaches the LEDs. Although 4v is low enough that most LEDs
can tolerate that much reverse voltage.

LEDs that change colour autonmously have been around for a while.

--
Regards,
Martin Brown

On Thursday, 21 December 2017 13:36:05 UTC, Martin Brown wrote:
On 21/12/2017 11:54, F wrote:
On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

Try it on 4.5v of batteries with a silicon diode in series (and a 500R
series resistor if you want oo be cautious).

That might prove difficult as I've tried to explain to a lecturer who was suprised I didn't keep 50 ohm resistors as a main stock item.

Resistors usually come in the E series so look for 470 ohms rather than 500, not that it'll make much differnce, but I'd try 330 and 220 at least.
I think 470 might be to high as that would only allow about 11ma for a typical single LED.


My instinct is that the first thing the thing does is rectify the AC to
DC before it reaches the LEDs.

It might not it may just use the +ve cycle to run the LED's as that's a cheap way of doing it.

Although 4v is low enough that most LEDs
can tolerate that much reverse voltage.

But if teh foward voltage is high that'll mean more current will flow and that is more likely to damaged the LEDs with over heating especially if run from DC at 100% duty cycle.


LEDs that change colour autonmously have been around for a while.

Not really the LEDs don'y do this by themselves they have an inbiuld chip that does this for them.
I've used these and then run on 5V DC they will probbaly work on 4V DC
but haven't tried them.

https://www.rapidonline.com/truopto-...ar-5mm-55-1904


--
Regards,
Martin Brown

On 21/12/2017 12:29, Bob Eager wrote:
On Thu, 21 Dec 2017 12:11:59 +0000, T i m wrote:

On Thu, 21 Dec 2017 11:54:50 +0000, F news@nowhere wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

It's basically just a transformer but to use one you would need to do
some wiring and put it in a suitable box etc.

4V is a bit of a funny one and the nearest I can find is:

https://www.maplin.co.uk/p/2x45v-6va...s-transformer-
a76qj

You can actually get 'empty' wall wart boxes that you could put said
transformer in for yourself ...

I found:

CPC TF01368 for the transformer

They also do wall wart boxes (I've used them to replace damaged ones),
although I can't find them right now.




Some bell transformers do 4v AC but they probably cost more than some
new lights.

"Bob Eager" wrote in message
...
On Thu, 21 Dec 2017 11:54:50 +0000, F wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

I should have looked at the picture more closely! I've looked and can't
see nything obvious - 4 volts AC at no more then 0.5A or so seems hard to
find.

One way to get that is to use one of the common multi tap transformers and
use a couple of taps, and not the normal 0 tap. Say use the 6V and 10V tap.

On 21/12/2017 11:54, F wrote:
On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for
one of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs
three sticks of 12 LED Christmas lights which gradually, and
individually, change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC
and not 4v DC. So, I'm still looking for a replacement wall wart.
Anyone?


https://www.amazon.co.uk/Greenbrook-...0II/ref=sr_1_2

The thing is as on that other thread, why is it AC?
Unless its using the mains for timing, then surely a dc supply will still
work.

I'm sure one could be made fairly simply from a normal small mains
transformer of the right type.

When dealing with AC though, you need to be careful to see what the load is
and what the actual peak to peak levels are not just the mean as measured
with a meter.


Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"F" news@nowhere wrote in message
news
On another thread (currently into a discussion on sound and phase) I asked
if anyone any thoughts on where I could get a replacement for one of
these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and not
4v DC. So, I'm still looking for a replacement wall wart. Anyone?

--
F

On 21/12/2017 12:40, Andrew Gabriel wrote:
In article ,
Bob Eager writes:
On Thu, 21 Dec 2017 11:54:50 +0000, F wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

I should have looked at the picture more closely! I've looked and can't
see nything obvious - 4 volts AC at no more then 0.5A or so seems hard to
find.

You might find the lights work fine on DC, in which case a 4.5VDC
supply would work

And they do! I bought the 4.5v AC to DC adapter from CPC: PW02731 from
the 'other' thread before I discovered the original failed unit was AC
to AC and so I plugged the lights into it on the 4.5v setting (they
wouldn't run at 3v).

Polarity doesn't appear to matter, and they're running a little brighter
than they did, the colours are less varied at any one time, but they work.

On that basis, is there anything to look out for?

--
F

On Fri, 22 Dec 2017 21:49:35 +0000, F news@nowhere wrote:

On 21/12/2017 12:40, Andrew Gabriel wrote:
In article ,
Bob Eager writes:
On Thu, 21 Dec 2017 11:54:50 +0000, F wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

I should have looked at the picture more closely! I've looked and can't
see nything obvious - 4 volts AC at no more then 0.5A or so seems hard to
find.

You might find the lights work fine on DC, in which case a 4.5VDC
supply would work

And they do! I bought the 4.5v AC to DC adapter from CPC: PW02731 from
the 'other' thread before I discovered the original failed unit was AC
to AC and so I plugged the lights into it on the 4.5v setting (they
wouldn't run at 3v).

Polarity doesn't appear to matter,

Correct. If it's AC then the 'polarity' is changing 50 times a second.
;-)

and they're running a little brighter
than they did,

4.5 instead of 4V?

the colours are less varied at any one time, but they work.

Hmmm ... ?

On that basis, is there anything to look out for?

Just that they could be being overdriven slightly so ('a little
brighter' ) so they may not last as long?

Because you are running AC there isn't much that you could do easily
to lower the output voltage to 4V (AC), especially if the load varies
a lot (no lights on, all lights on etc).

You could try a series resistor (as mentioned elsewhere) but that
would really only affect the 'lights all on' condition.

You might be able to 'clamp' the voltage with a pair of back to back
(3.4V?) zener diodes (to clamp the peak voltage(s)), with reverse
biased rectifier diodes in series (to stop the zener conducting on the
forward biased half cycle) and a series resistor between transformer
and diodes (to limit the current) but you will need a real electronics
design engineer to help you on that one. ;-)

Cheers, T i m

On Friday, 22 December 2017 23:07:55 UTC, T i m wrote:
On Fri, 22 Dec 2017 21:49:35 +0000, F news@nowhere wrote:
On 21/12/2017 12:40, Andrew Gabriel wrote:
In article ,
Bob Eager writes:
On Thu, 21 Dec 2017 11:54:50 +0000, F wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

I should have looked at the picture more closely! I've looked and can't
see nything obvious - 4 volts AC at no more then 0.5A or so seems hard to
find.

You might find the lights work fine on DC, in which case a 4.5VDC
supply would work

And they do! I bought the 4.5v AC to DC adapter from CPC: PW02731 from
the 'other' thread before I discovered the original failed unit was AC
to AC and so I plugged the lights into it on the 4.5v setting (they
wouldn't run at 3v).

Polarity doesn't appear to matter,

Correct. If it's AC then the 'polarity' is changing 50 times a second.
;-)

and they're running a little brighter
than they did,

4.5 instead of 4V?

the colours are less varied at any one time, but they work.

Hmmm ... ?

On that basis, is there anything to look out for?

Just that they could be being overdriven slightly so ('a little
brighter' ) so they may not last as long?

Because you are running AC there isn't much that you could do easily
to lower the output voltage to 4V (AC), especially if the load varies
a lot (no lights on, all lights on etc).

You could try a series resistor (as mentioned elsewhere) but that
would really only affect the 'lights all on' condition.

You might be able to 'clamp' the voltage with a pair of back to back
(3.4V?) zener diodes (to clamp the peak voltage(s)), with reverse
biased rectifier diodes in series (to stop the zener conducting on the
forward biased half cycle) and a series resistor between transformer
and diodes (to limit the current) but you will need a real electronics
design engineer to help you on that one. ;-)

Cheers, T i m

It's not hard to drop the half volt but if it works ok, great, don't worry.


NT

On Fri, 22 Dec 2017 15:46:47 -0800 (PST), wrote:

snip

And they do! I bought the 4.5v AC to DC adapter from CPC: PW02731 from
the 'other' thread before I discovered the original failed unit was AC
to AC and so I plugged the lights into it on the 4.5v setting (they
wouldn't run at 3v).

snip

It's not hard to drop the half volt

Oooo ... two std rectifier diodes back to back in one output leg? ;-)

but if it works ok, great, don't worry.

But it doesn't does it and for how it's working (brighter), for how
long?

From my experience of these things, potentially 'overdriven' LEDs
don't tend to last that long?

Cheers, T i m

On 22/12/2017 23:07, T i m wrote:
On Fri, 22 Dec 2017 21:49:35 +0000, F news@nowhere wrote:

On 21/12/2017 12:40, Andrew Gabriel wrote:
In article ,
Bob Eager writes:
On Thu, 21 Dec 2017 11:54:50 +0000, F wrote:

On another thread (currently into a discussion on sound and phase) I
asked if anyone any thoughts on where I could get a replacement for one
of these: https://www.flickr.com/gp/161457453@N02/iv5D72. It runs three
sticks of 12 LED Christmas lights which gradually, and individually,
change colour.

I've taken it to pieces now and it turns out it's 240v AC to 4v AC and
not 4v DC. So, I'm still looking for a replacement wall wart. Anyone?

I should have looked at the picture more closely! I've looked and can't
see nything obvious - 4 volts AC at no more then 0.5A or so seems hard to
find.

You might find the lights work fine on DC, in which case a 4.5VDC
supply would work

And they do! I bought the 4.5v AC to DC adapter from CPC: PW02731 from
the 'other' thread before I discovered the original failed unit was AC
to AC and so I plugged the lights into it on the 4.5v setting (they
wouldn't run at 3v).

Polarity doesn't appear to matter,

Correct. If it's AC then the 'polarity' is changing 50 times a second.
;-)

and they're running a little brighter
than they did,

4.5 instead of 4V?

the colours are less varied at any one time, but they work.

Hmmm ... ?

On that basis, is there anything to look out for?

Just that they could be being overdriven slightly so ('a little
brighter' ) so they may not last as long?

Because you are running AC there isn't much that you could do easily
to lower the output voltage to 4V (AC), especially if the load varies
a lot (no lights on, all lights on etc).

Thanks, but I'm running them from the AV to DC adapter that I bought so
they're on 4.5v DC.

--
F

On Sat, 23 Dec 2017 00:19:29 +0000, F news@nowhere wrote:

snip
Because you are running AC there isn't much that you could do easily
to lower the output voltage to 4V (AC), especially if the load varies
a lot (no lights on, all lights on etc).

Thanks, but I'm running them from the AV to DC adapter that I bought so
they're on 4.5v DC.

Ah, sorry, my bad (it's late I'm tired ... ). ;-)

Ok, so it would be even easier to drop the voltage a bit so that you
don't see the extra brightness / less change in colour and may even
prevent them from dying early.

Basically, if you were to fit a silicone rectifier diode in series
with one of the leads to the lights, it will drop about .6V and may
make it more like it was originally?

4.5V is 25% higher than it was designed to run and that can be quite a
bit where LEDs that may already be driven reasonably hard are
concerned.

If the original adaptor was only 1VA then at 4V that is only about
250mA so a 1A diode should be ok (even at the price you could wire a
couple in parallel)?

https://www.diodes.com/assets/Datasheets/ds28002.pdf

https://www.maplin.co.uk/p/1n4001s-1...ectifier-ql73q

If the (DIN was it) plug is re-wireable you could even put the
diode(s) in there?

Cheers, T i m

On Sat, 23 Dec 2017 00:48:27 +0000, T i m wrote:

On Sat, 23 Dec 2017 00:19:29 +0000, F news@nowhere wrote:

snip
Because you are running AC there isn't much that you could do easily
to lower the output voltage to 4V (AC), especially if the load varies
a lot (no lights on, all lights on etc).

Thanks, but I'm running them from the AV to DC adapter that I bought so
they're on 4.5v DC.

Ah, sorry, my bad (it's late I'm tired ... ). ;-)

Ok, so it would be even easier to drop the voltage a bit so that you
don't see the extra brightness / less change in colour and may even
prevent them from dying early.

Basically, if you were to fit a silicone rectifier diode in series with
one of the leads to the lights, it will drop about .6V and may make it
more like it was originally?

4.5V is 25% higher than it was designed to run

Um...?
--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

On 23 Dec 2017 09:37:35 GMT, Bob Eager wrote:

On Sat, 23 Dec 2017 00:48:27 +0000, T i m wrote:

On Sat, 23 Dec 2017 00:19:29 +0000, F news@nowhere wrote:

snip
Because you are running AC there isn't much that you could do easily
to lower the output voltage to 4V (AC), especially if the load varies
a lot (no lights on, all lights on etc).

Thanks, but I'm running them from the AV to DC adapter that I bought so
they're on 4.5v DC.

Ah, sorry, my bad (it's late I'm tired ... ). ;-)

Ok, so it would be even easier to drop the voltage a bit so that you
don't see the extra brightness / less change in colour and may even
prevent them from dying early.

Basically, if you were to fit a silicone rectifier diode in series with
one of the leads to the lights, it will drop about .6V and may make it
more like it was originally?

4.5V is 25% higher than it was designed to run

Um...?

LOL ... I did say I was tired didn't I Bob. ;-(

Ok, how about a 12.5% increase? (which is still 'quite a bit' where
LEDs are concerned). ;-)

Cheers, T i m

In article ,
says...


Just that they could be being overdriven slightly so ('a little
brighter' ) so they may not last as long?

Because you are running AC there isn't much that you could do easily
to lower the output voltage to 4V (AC), especially if the load varies
a lot (no lights on, all lights on etc).

You could try a series resistor (as mentioned elsewhere) but that
would really only affect the 'lights all on' condition.


Don't forget that 4VAC is 5.66V peak. Assuming tha there is a
silicon diode in the lights themselves, the actual resulting
DC voltage might be as high as 5V if there is a fair sized
electrolytic smoothing the output and allowing for the typical
0.7V drop across the diode.

With 4.5VDC fed to the same diode, the same forward drop will
still be experienced, leaving only 3.8V on the output of the
diode.

Checking back, I note that the OP says that 'Polarity doesn't
appear to matter' which implies a bridge rectifier. This will
have twice the diode forward voltage drop so 4.25VDC maximum
from a 4VAC input or 3.1V on the bridge output from a 4.5VDC
input.

On that basis, I wouldn't bother to do anything further.

--

Terry

---
This email has been checked for viruses by AVG.
http://www.avg.com