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Multi Coloured LED 120v help
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DJ Delorie
electronics forum Guru Wannabe


Joined: 28 Apr 2005
Posts: 183

PostPosted: Mon Jul 17, 2006 3:27 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

Likely, the AC 50% duty cycle keeps resetting the chip inside the LED.
Try a small half-wave or full-wave rectifier to provide DC instead.
You might need to increase the R value, though.
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Don Klipstein
electronics forum Guru Wannabe


Joined: 02 May 2005
Posts: 297

PostPosted: Mon Jul 17, 2006 5:06 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

In <1153101093.913820.319270@35g2000cwc.googlegroups.com>, steve wrote:

Quote:
On many occations I have used the following circuit to tell me when I
have left light swiches on.

120v AC----R100k---.--------.
| |
| |
Diode LED
| |
| |
.________.
|
.
------------------------

Recently I bought an LED that cycles through three colours, red green
blue I believe.
However when I use the above circuit It just seems to light up with a
red light. It does not cycle through the nice red/green/blue cycle. The
guy in the electronic store said it was 3 volt led. I tried a lesser
Rvalue 69 and then a higher 120, but all to no avail. It Just glows
red. The led is clear and is one of those larger ones. You know there
are the normal size that are commonly used and then there are the next
commonly larger size. This is that larger size.
I have put a battery on it and it seems to work ok just alone. Can
anyone help me on this.

Maybe these fancy LEDs with little chips ?? in them to make them rotate
the three colours dont lend themselves to be used in this way??? Any
advice.

I expect that the chip in that LED is resetting between AC cycles when
the LED is not getting any power. It will need rectification and some
filtering of the 120VAC.

I have another concern: Does its current consumption drop when it
changes color or between any PWM pulses of any fading that some of these
LEDs have between colors? If so, then the voltage reaching the LED
through the resistor can spike to excessive levels and I suspect that
could blow the chip. A zener diode, I would guess 5.1V, in parallel with
the LED can protect the LED from that.

- Don Klipstein (don@misty.com)
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steve
electronics forum beginner


Joined: 20 Dec 2005
Posts: 36

PostPosted: Mon Jul 17, 2006 5:51 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

DJ Delorie wrote:
Quote:
Likely, the AC 50% duty cycle keeps resetting the chip inside the LED.
Try a small half-wave or full-wave rectifier to provide DC instead.
You might need to increase the R value, though.

DJ

Thank you for your suggestion. Can you recomend one each of these that
i can get and try.
Im a novice and want to make sure I try the right thing.

Regards
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steve
electronics forum beginner


Joined: 20 Dec 2005
Posts: 36

PostPosted: Mon Jul 17, 2006 5:54 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

Don Klipstein wrote:
Quote:
In <1153101093.913820.319270@35g2000cwc.googlegroups.com>, steve wrote:

On many occations I have used the following circuit to tell me when I
have left light swiches on.

120v AC----R100k---.--------.
| |
| |
Diode LED
| |
| |
.________.
|
.
------------------------

Recently I bought an LED that cycles through three colours, red green
blue I believe.
However when I use the above circuit It just seems to light up with a
red light. It does not cycle through the nice red/green/blue cycle. The
guy in the electronic store said it was 3 volt led. I tried a lesser
Rvalue 69 and then a higher 120, but all to no avail. It Just glows
red. The led is clear and is one of those larger ones. You know there
are the normal size that are commonly used and then there are the next
commonly larger size. This is that larger size.
I have put a battery on it and it seems to work ok just alone. Can
anyone help me on this.

Maybe these fancy LEDs with little chips ?? in them to make them rotate
the three colours dont lend themselves to be used in this way??? Any
advice.

I expect that the chip in that LED is resetting between AC cycles when
the LED is not getting any power. It will need rectification and some
filtering of the 120VAC.

I have another concern: Does its current consumption drop when it
changes color or between any PWM pulses of any fading that some of these
LEDs have between colors? If so, then the voltage reaching the LED
through the resistor can spike to excessive levels and I suspect that
could blow the chip. A zener diode, I would guess 5.1V, in parallel with
the LED can protect the LED from that.

- Don Klipstein (don@misty.com)

Thanks Don,
Rectification seems to be what someone else said too.
The Zener diode is a good idea too. however am I wrong in thinking that
the higher the R the higher the wattage of the resister 1/2 or more
should be used?
Regards
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Don Klipstein
electronics forum Guru Wannabe


Joined: 02 May 2005
Posts: 297

PostPosted: Mon Jul 17, 2006 7:05 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

In <1153115699.802368.147960@p79g2000cwp.googlegroups.com>, steve wrote:
Quote:

Don Klipstein wrote:
In <1153101093.913820.319270@35g2000cwc.googlegroups.com>, steve wrote:

On many occations I have used the following circuit to tell me when I
have left light swiches on.

<SNIP circuit and bits on the color-changing LED having a chip for space>

Quote:
I expect that the chip in that LED is resetting between AC cycles when
the LED is not getting any power. It will need rectification and some
filtering of the 120VAC.

I have another concern: Does its current consumption drop when it
changes color or between any PWM pulses of any fading that some of these
LEDs have between colors? If so, then the voltage reaching the LED
through the resistor can spike to excessive levels and I suspect that
could blow the chip. A zener diode, I would guess 5.1V, in parallel with
the LED can protect the LED from that.

- Don Klipstein (don@misty.com)

Thanks Don,
Rectification seems to be what someone else said too.
The Zener diode is a good idea too. however am I wrong in thinking that
the higher the R the higher the wattage of the resister 1/2 or more
should be used?

Actually, the lower the resistor value the more current will flow and
power dissipated in the resistor will increase as its value is decreased.

For a worst case, assume that the load voltage will be small and nearly
the full rectified/filtered 120VAC (169 volts DC) will be across the
resistor. That will dissipate about .285 watt into a 100K resistor.
This is assuming that you have a rectifier and filter capacitor and the
resistor is downstream from the filter capacitor.

If the resistor is 100K and you rectify and filter 120VAC, I would
recommend a 1/2 watt resistor.

Keep in mind that this will pass only about 1.6 milliamps, which is
fairly likely to be quite low for a color-changing LED.

Allowing more current with reasonable parts and reasonable heat
dissipation gets into the more complicated matter of having a capacitor
rather than a resistor limiting the average current, plus a resistor to
limit peak switch-on current into this whole thing, and the capacitor
having an actual AC rating since many capacitors do not do well with long
term application of AC merely having peak voltage below the capacitor's DC
voltage rating.

It is starting to appear to me that the simplest way to power a low
voltage color-changing LED from 120VAC is to use a "wall wart" with low
voltage DC output, a 7805 or similar 5 volt regulator, and a dropping
resistor that drops about 1.5 volts (5 volts minus typical LED voltage)
at 20 or 30 mA, which is basically 47 or 68 ohms. However, I expect 100
to 220 ohms to work OK with tolerable reduction of light output and 33
ohms to overheat the LED only a little if at all.

Meanwhile, there are some color-changing LED "nightlight bulbs" (and
complete nightlights with such removable candelabra-base bulbs) on the
market. I somewhat remember that Target is where I bought the two that I
have, although I do not guarantee that you will find those at your nearest
Target.

That product is reviewed by Craig Johnson
("LED Museum" / "Punishment Zone") at:

http://ledmuseum.thefire.us/tarnl.htm

- Don Klipstein (don@misty.com)
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redbelly
electronics forum Guru Wannabe


Joined: 29 May 2005
Posts: 210

PostPosted: Mon Jul 17, 2006 9:27 pm    Post subject: Re: Multi Coloured LED 120v help Reply with quote

steve wrote:
Quote:
On many occations I have used the following circuit to tell me when I
have left light swiches on.

(snip)


In addition to the others' suggestions, I would test the LED with a 9V
battery and appropriate resistor. First convince yourself that the LED
works correctly with a simple DC source before playing around with
rectifiers and such.

Mark
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steve
electronics forum beginner


Joined: 20 Dec 2005
Posts: 36

PostPosted: Tue Jul 18, 2006 12:39 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

redbelly wrote:
Quote:
steve wrote:
On many occations I have used the following circuit to tell me when I
have left light swiches on.

(snip)

In addition to the others' suggestions, I would test the LED with a 9V
battery and appropriate resistor. First convince yourself that the LED
works correctly with a simple DC source before playing around with
rectifiers and such.

Mark
After I wired it up as in my first diagram I tested the led to see if

it still works after connecting to the 120. I tested it with a batery
and it works fine. So my circuit has not burned the led it just doenst
change colours as it is suppose to.

Regards
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petrus bitbyter
electronics forum Guru


Joined: 24 Mar 2005
Posts: 363

PostPosted: Tue Jul 18, 2006 1:24 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

"steve" <stevesemple@lycos.com> schreef in bericht
news:1153183183.635593.61180@b28g2000cwb.googlegroups.com...
Quote:

redbelly wrote:
steve wrote:
On many occations I have used the following circuit to tell me when I
have left light swiches on.

(snip)

In addition to the others' suggestions, I would test the LED with a 9V
battery and appropriate resistor. First convince yourself that the LED
works correctly with a simple DC source before playing around with
rectifiers and such.

Mark
After I wired it up as in my first diagram I tested the led to see if
it still works after connecting to the 120. I tested it with a batery
and it works fine. So my circuit has not burned the led it just doenst
change colours as it is suppose to.

Regards


So you're not talking about a LED but about an IC that contains three LEDs
and some other electronics. This type of circuits tend to have type number
and specifications described in a data sheet. It should help if you could
tell something about it.

Even if you can't tell something about the part, it apparently works with a
battery. What battery and what series resistor did you use? Do you have a
multimeter so you can tell something about voltages acros battery, resistor
and LED? If you don't have such an instrument you'd better buy one that's to
say if you want to do something with electronics. A simple one costs around
?10,--. Good enough for a beginner.

The circuit below may work but I can't be sure due to lack of information.
Beware! Circuits directly connected to the mains are always dangerous.

100k/.5W bridge
___ rectifier
----|___|--+ .-----.
+-| ~/ |---------+-------+
120Vac +--| / = |--+ | |
| '-----' | | .-.
----------+ | | | |1k
| | + | |
| ### '-'
| --- |
| |100uF | LED
| | V circuit
| | -
| | |
+------+-------+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

petrus bitbyter
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Warren Weber
electronics forum addict


Joined: 19 May 2005
Posts: 52

PostPosted: Tue Jul 18, 2006 2:15 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

"steve" <stevesemple@lycos.com> wrote in message
news:1153101093.913820.319270@35g2000cwc.googlegroups.com...
Quote:
On many occations I have used the following circuit to tell me when I
have left light swiches on.

120v AC----R100k---.--------.
| |
| |
Diode LED
| |
| |
.________.
|
.
------------------------

Recently I bought an LED that cycles through three colours, red green
blue I believe.
However when I use the above circuit It just seems to light up with a
red light. It does not cycle through the nice red/green/blue cycle. The
guy in the electronic store said it was 3 volt led. I tried a lesser
Rvalue 69 and then a higher 120, but all to no avail. It Just glows
red. The led is clear and is one of those larger ones. You know there
are the normal size that are commonly used and then there are the next
commonly larger size. This is that larger size.
I have put a battery on it and it seems to work ok just alone. Can
anyone help me on this.

Maybe these fancy LEDs with little chips ?? in them to make them rotate
the three colours dont lend themselves to be used in this way??? Any
advice.

Thank You

Steve.. Think simple. Use a Neon lamp. I do this where the switch is outside
the room with the light. Such as a walk in closet. W W
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jasen
electronics forum Guru Wannabe


Joined: 18 Jun 2006
Posts: 204

PostPosted: Tue Jul 18, 2006 7:34 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

On 2006-07-17, steve <stevesemple@lycos.com> wrote:
Quote:
On many occations I have used the following circuit to tell me when I
have left light swiches on.

120v AC----R100k---.--------.
| |
| |
Diode LED
| |
| |
.________.
|
.
------------------------

Recently I bought an LED that cycles through three colours, red green
blue I believe.
However when I use the above circuit It just seems to light up with a
red light. It does not cycle through the nice red/green/blue cycle.

perhaps the LED needs continuous DC. not pulsed like that circuit gives,
stick a 10uF capacitor in parallel with the led and another diode in series
with the pair.


120v AC----R100k---+--->|---+----.
| | |
| \V/ |
Diode LED ===
/A\ | |
| | |
`---+----+----'
|
-----------------------'

Bye.
Jasen
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steve
electronics forum beginner


Joined: 20 Dec 2005
Posts: 36

PostPosted: Tue Jul 18, 2006 3:47 pm    Post subject: Re: Multi Coloured LED 120v help Reply with quote

jasen wrote:
Quote:
On 2006-07-17, steve <stevesemple@lycos.com> wrote:
On many occations I have used the following circuit to tell me when I
have left light swiches on.

120v AC----R100k---.--------.
| |
| |
Diode LED
| |
| |
.________.
|
.
------------------------

Recently I bought an LED that cycles through three colours, red green
blue I believe.
However when I use the above circuit It just seems to light up with a
red light. It does not cycle through the nice red/green/blue cycle.

perhaps the LED needs continuous DC. not pulsed like that circuit gives,
stick a 10uF capacitor in parallel with the led and another diode in series
with the pair.


120v AC----R100k---+--->|---+----.
| | |
| \V/ |
Diode LED ===
/A\ | |
| | |
`---+----+----'
|
-----------------------'

Bye.
Jasen

Thanks Jasen I will give this a try.
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steve
electronics forum beginner


Joined: 20 Dec 2005
Posts: 36

PostPosted: Tue Jul 18, 2006 3:59 pm    Post subject: Re: Multi Coloured LED 120v help Reply with quote

petrus bitbyter wrote:
Quote:
"steve" <stevesemple@lycos.com> schreef in bericht
news:1153183183.635593.61180@b28g2000cwb.googlegroups.com...

redbelly wrote:
steve wrote:
On many occasions I have used the following circuit to tell me when I
have left light switches on.

(snip)

In addition to the others' suggestions, I would test the LED with a 9V
battery and appropriate resistor. First convince yourself that the LED
works correctly with a simple DC source before playing around with
rectifiers and such.

Mark
After I wired it up as in my first diagram I tested the led to see if
it still works after connecting to the 120. I tested it with a battery
and it works fine. So my circuit has not burned the led it just doesnt
change colours as it is suppose to.

Regards


So you're not talking about a LED but about an IC that contains three LEDs
and some other electronics. This type of circuits tend to have type number
and specifications described in a data sheet. It should help if you could
tell something about it.

Even if you can't tell something about the part, it apparently works with a
battery. What battery and what series resistor did you use? Do you have a
multimeter so you can tell something about voltages across battery, resistor
and LED? If you don't have such an instrument you'd better buy one that's to
say if you want to do something with electronics. A simple one costs around
?10,--. Good enough for a beginner.

The circuit below may work but I can't be sure due to lack of information.
Beware! Circuits directly connected to the mains are always dangerous.

100k/.5W bridge
___ rectifier
----|___|--+ .-----.
+-| ~/ |---------+-------+
120Vac +--| / = |--+ | |
| '-----' | | .-.
----------+ | | | |1k
| | + | |
| ### '-'
| --- |
| |100uF | LED
| | V circuit
| | -
| | |
+------+-------+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

petrus bitbyter
Thanks for your helpfull suggestion.


Unfortunately the store I bought the part at was one of those re
package stores, eg it came in a plain little plastic bag. The store guy
said that it was 3 volts, unfortunetely I dont know how many ma. He
showed it to me using a flat watch battery about the size of a dime. I
have tested it with my diode/continuity setting on my multimeter and it
works fine.
Last night I took a little rectifier and put on bread board put, house
current on it 117v AC and then tested the output on it with my
multimeter on dc. It shows about 105 volts. I tried the led as wired in
my first diagram on my first post and got no light at all. I then tried
the same thing with a normal led and it worked fine.

Not sure why it works ok with normal led but this one it does not work
with. By the way Im sure your right about the 3 colour led its probably
more IC than LED. In fact when I look at the individual light component
in the led lens they are flat not the normal sort of stork looking
thing with a long leg.

I will try the diagram you have posted and get back to you . I might
also go to another store and see if I can get another different 3
coloured light.

Regards
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steve
electronics forum beginner


Joined: 20 Dec 2005
Posts: 36

PostPosted: Wed Jul 19, 2006 2:22 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

petrus bitbyter wrote:
Quote:
"steve" <stevesemple@lycos.com> schreef in bericht
news:1153183183.635593.61180@b28g2000cwb.googlegroups.com...

redbelly wrote:
steve wrote:
On many occations I have used the following circuit to tell me when I
have left light swiches on.

(snip)

In addition to the others' suggestions, I would test the LED with a 9V
battery and appropriate resistor. First convince yourself that the LED
works correctly with a simple DC source before playing around with
rectifiers and such.

Mark
After I wired it up as in my first diagram I tested the led to see if
it still works after connecting to the 120. I tested it with a batery
and it works fine. So my circuit has not burned the led it just doenst
change colours as it is suppose to.

Regards


So you're not talking about a LED but about an IC that contains three LEDs
and some other electronics. This type of circuits tend to have type number
and specifications described in a data sheet. It should help if you could
tell something about it.

Even if you can't tell something about the part, it apparently works with a
battery. What battery and what series resistor did you use? Do you have a
multimeter so you can tell something about voltages acros battery, resistor
and LED? If you don't have such an instrument you'd better buy one that's to
say if you want to do something with electronics. A simple one costs around
?10,--. Good enough for a beginner.

The circuit below may work but I can't be sure due to lack of information.
Beware! Circuits directly connected to the mains are always dangerous.

100k/.5W bridge
___ rectifier
----|___|--+ .-----.
+-| ~/ |---------+-------+
120Vac +--| / = |--+ | |
| '-----' | | .-.
----------+ | | | |1k
| | + | |
| ### '-'
| --- |
| |100uF | LED
| | V circuit
| | -
| | |
+------+-------+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

petrus bitbyter
I put together your circuit and sure enough it did the trick.

Thank you. The led is really quite something. The program is not just
coloured lights that flash one colour and move to the next its seems to
run a little program that must be 15 to 20 seconds long before it
recycles over again. It circulates the colours and then pauses and sort
of pauses through all the colours. This may be all a mater of routine
for all of you but its amazing how much they can pack into one of
these. Thank you again.

Regards
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steve
electronics forum beginner


Joined: 20 Dec 2005
Posts: 36

PostPosted: Wed Jul 19, 2006 2:25 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

Jason,

I am going to try your ciruit to see what it does to this led. However
I discovered I dont have any 10uf Capacitors so I have to go to the
store. By the way Im guessing that I would use a capacitor that is NOT
polerized. Am I right ??

Regards
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Lord Garth
electronics forum Guru


Joined: 24 Mar 2005
Posts: 363

PostPosted: Wed Jul 19, 2006 2:36 am    Post subject: Re: Multi Coloured LED 120v help Reply with quote

"steve" <stevesemple@lycos.com> wrote in message
news:1153275902.773530.46460@h48g2000cwc.googlegroups.com...
Quote:
Jason,

I am going to try your ciruit to see what it does to this led. However
I discovered I dont have any 10uf Capacitors so I have to go to the
store. By the way Im guessing that I would use a capacitor that is NOT
polerized. Am I right ??

Regards


You should use an X2 rated capacitor. These are in most switching power
supplies and in folded fluorescent bulbs. Look for the X2 on the label.
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