Previous in Forum: CSI Lamp Control Gear   Next in Forum: Multiple Chargers for Batteries
Close
Close
Close
39 comments
Rate Comments: Nested
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Marine Engineering - New Member

Join Date: Sep 2008
Location: Vancleave, Ms about 30 miles inland from Biloxi and the coast
Posts: 3197
Good Answers: 106

LED Operating Current

03/01/2014 3:03 PM

Will an LED operate on AC or is it a DC only device?

__________________
Mr.Ron from South Ms.
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru
Engineering Fields - Optical Engineering - Member Engineering Fields - Engineering Physics - Member Engineering Fields - Systems Engineering - Member

Join Date: Apr 2010
Location: Trantor
Posts: 5363
Good Answers: 647
#1

Re: LED operating current

03/01/2014 3:31 PM

Typical LEDs operate on about 3 VDC, and can be dimmed by carefully regulating the current, or via pulse-width modulation.

Since they are diodes, I suppose they would glow when the current is flowing in the proper direction. They'd probably flicker at whatever the AC frequency is.

__________________
Whiskey, women -- and astrophysics. Because sometimes a problem can't be solved with just whiskey and women.
Register to Reply
Guru

Join Date: Feb 2011
Posts: 7025
Good Answers: 207
#2

Re: LED operating current

03/01/2014 5:30 PM

what are you trying to do? an LED is a diode, DC stuff

Register to Reply
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15600
Good Answers: 981
#3

Re: LED operating current

03/01/2014 6:55 PM

As the acronym states, an LED is a diode. A diode will only readily conduct in one direction. The reverse breakdown voltage of every LED I know of is less than the peak voltage of most "wall wort" AC supplies. None can handle the reverse or forward voltage of any power distribution level.

__________________
"Don't disturb my circles." translation of Archimedes last words
Register to Reply
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#4
In reply to #3

Re: LED operating current

03/01/2014 11:55 PM

I'm pretty sure that they can survive a PIV of at least 5V. From experience, a back to front LED in a TTL circuit doesn't die...it still works fine when it's turned around and put back in the right way.

It will work fine at say 3 to 5 VAC.

Having a go would be a pretty cheap experiment.

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#5

Re: LED operating current

03/02/2014 3:38 AM

A possible fix, is to place two LEDs, "back to back", assuming of course that there is some form of current limiting in circuit and that maximum PIVs of the LEDs are not ignored.

One LED will light on one half cycle, the other on the reverse half cycle.

It is possible that a series High PIV (normal) diode should be included in each half to make the circuit even more reliable with regard to noise and spikes......though I have never personally actually tried either method......theory only.

A further possible method is to add a tiny full wave rectifier in the circuit (they cost very little nowadays). SMD ones strong enough for a LED, are probably smaller than a second LED!!! Some capacitance may be needed to "get rid of the lumpy DC!" I have not tried this either.

Even though a mains LED with current/voltage control should work if carefully designed, unless a transformer or similar is also in circuit, it may be still be at mains voltage with regard to earth. DANGEROUS!!

Therefore using normal LED mounting hardware may prove very dangerous to any user, as it is usually designed to insulate from less than 5 volts.....not 120VAC or even 230VAC......Use mains rated hardware for say mains lamps, modified to take a LED in some manner....

I would also suggest that using an isolating, voltage reducing transformer for LED illumination, should be recommended......

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru

Join Date: Jun 2006
Location: Ottawa Canada
Posts: 1975
Good Answers: 117
#8
In reply to #5

Re: LED operating current

03/02/2014 9:04 AM

Put them back to back in series and NOTHING will flow. Parallel them, and you will get a lovely 2 LED light which will be really pretty. I tried this before I posted actually! (used two 10 to 1 transformers to bring it down to a reasonable voltage. The final voltage was NOT 1.5 volts but rather more than twice that. I think that was because of the high impedance (? resistance?) of the diodes.)

__________________
If it was easy anybody could do it.
Register to Reply
Guru

Join Date: Jul 2005
Location: Stoke-on-Trent, UK
Posts: 4496
Good Answers: 137
#11
In reply to #8

Re: LED operating current

03/02/2014 10:44 AM

Back to back in series and NOTHING will flow was my initial reaction, but AG didn't say in series. He didn't say in parallel either, probably thinking we could work it out for ourselves .

__________________
Give masochists a fair crack of the whip
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#16
In reply to #8

Re: LED operating current

03/02/2014 1:12 PM

Great! Thanks for the testing too. It was partly only an idea that I played around with in my head sometime ago....

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#17
In reply to #16

Re: LED operating current

03/02/2014 1:41 PM

I don't care what anyone says...it's always cool to independently come up with an idea that already exists.

For all we know, you might have been the first.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#18
In reply to #17

Re: LED operating current

03/02/2014 3:07 PM

Thanks, but looking at the good link you posted, its obviously been sometime they have been working on it.....I am just a "Johnny come lately!"......sadly!

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#19
In reply to #18

Re: LED operating current

03/02/2014 3:39 PM

Well, I can't blame them for keeping it under wraps.

LEDs are going to be the way to go. It took the massive waste of time and money on CFL bulbs, to really kick it into gear.

I saw a pack of CFLs the other day, for about 50 cents apiece. Problem is, they are absolute garbage.

I've got enough incandescents to last until LEDs are up, running and affordable.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#21
In reply to #19

Re: LED operating current

03/03/2014 7:01 AM

I have bought mains LED replacement lamps from Eachbuyer, that seem to be fantastic price and performance wise, though they have only been installed for about 3 months.....so its early days still.....

They took a few weeks to arrive, which implies that what I ordered was not available in the German warehouse. You take the luck of the draw on that.....

Look here:-

http://www.eachbuyer.com/?gclid=CLjUm7mn9rwCFQcTwwodUQwAHA

The offers with say 4, 6 or 8 lamps at a time, really chop the price down......

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#22
In reply to #21

Re: LED operating current

03/03/2014 7:15 AM

Yeah. The prices are slowly coming down here too.

Ultimately, I want to go with dimmable can lighting throughout the house, like we talked about here.

cr4.globalspec.com/thread/72760

I'm going to wait a little longer to take the plunge. I don't even have a flatscreen TV yet.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#25
In reply to #22

Re: LED operating current

03/03/2014 10:41 AM

Till my large & heavy CRT TV is defective, I won't buy one either, although for football & F1 racing......it would be great....

Though I do have a Video projector as well - "Just in case!" But seldom used, except when teaching....

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#26
In reply to #25

Re: LED operating current

03/03/2014 12:35 PM

Me too. I've never known anything different, so the picture is just fine.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#28
In reply to #26

Re: LED operating current

03/04/2014 3:09 AM

Yup!!!

The first large screen TVs had major problems with both contrast and movement. Blacks that were light greys and smear for movement!!!

A simple check for the movement is to make say a video of say grass (patterned wallpaper also works!), moving the camera and then view it on an LCD screen. If the picture "pumps" it ha the problem. Many still do not know this.....Ticker displays can also become unreadable......the shop TV test films usually have/had little fast movement for that reason....

My brother bought a flat screen TV about 10 years ago that was simply awful, you could not watch a football match due to the grass.....He was totally pissed at me when I told him how badly it had done in tests against other models, others both better and cheaper.......it was an impulse buy.....his wife had also told him what a piece of crap it was too.....so he could repent at leisure......

One year later it was gone when I visited!!!! I WONDER WHY?!?!? I did not dare ask!!!!

A modern flatscreen TV should have neither problem, but if I was buying, I would check carefully for both faults and NOT buy either a 4K or even a 3-D model, who needs that crap except kids (young and old!).....and save a bundle at the same time......

Marking as Off Topic.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply Off Topic (Score 5)
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#6

Re: LED operating current

03/02/2014 8:37 AM

I'd say that AC driven LEDs, (beyond stings of Christmas lights), will be around soon.

http://www.ledsmagazine.com/articles/2006/05/running-leds-from-an-ac-supply.html

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru

Join Date: Feb 2011
Posts: 7025
Good Answers: 207
#7
In reply to #6

Re: LED operating current

03/02/2014 8:45 AM

not without a driver, you wont, they will still be diodes

Register to Reply
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#9
In reply to #7

Re: LED operating current

03/02/2014 9:27 AM

It goes beyond my pay grade, but it looks like it depends on who you talk to.

http://www.allledlighting.com/author.asp?section_id=543&doc_id=560225

I can't tell what these people are doing.

http://www.mouser.com/new/seoulsemiconductor/seoulacrich2/

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#10
In reply to #7

Re: LED operating current

03/02/2014 9:50 AM

This looks like a qualifier:

http://www.faqs.org/patents/app/20120091906

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru

Join Date: Feb 2011
Posts: 7025
Good Answers: 207
#12
In reply to #10

Re: LED operating current

03/02/2014 10:49 AM

sort of, they're still splitting an AC wave to get DC, I meant not a true AC diode, but good searching on your part

Register to Reply
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#13
In reply to #12

Re: LED operating current

03/02/2014 11:00 AM

I'm always interested in cheap, efficient, anything...as long as it works.

How it works, is secondary, but still interesting.

I'm surprised that they haven't been able to create light by using graphene.

Edit: I spoke too soon.

http://www.understandingnano.com/graphene-light.html

Is this just hype, and still running on DC?

http://www.zdnet.com/blog/gadgetreviews/philips-debuts-worlds-first-ac-powered-white-light-oled-module/17847

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru

Join Date: Feb 2011
Posts: 7025
Good Answers: 207
#14
In reply to #13

Re: LED operating current

03/02/2014 11:03 AM

don't worry you'll be seeing plenty of graphene based products

Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#15
In reply to #6

Re: LED operating current

03/02/2014 1:10 PM

Good link, many thanks. My guesswork ideas were nearer fact than even I thought....

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Associate

Join Date: Dec 2010
Location: Australia
Posts: 46
Good Answers: 5
#20

Re: LED Operating Current

03/02/2014 5:37 PM

yes, no, yes, no, smoke, flash, no...

__________________
Have you tried turning it off and on?
Register to Reply
Commentator

Join Date: Jul 2013
Posts: 56
Good Answers: 1
#23

Re: LED Operating Current

03/03/2014 9:38 AM

We use to hook up a tri color LED so

RED = dc+

Green = dc-

Orange = Ac (both fired)

Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#27
In reply to #23

Re: LED Operating Current

03/04/2014 2:57 AM

Thats a very useful idea for a simple double indication with either AC or DC! Thanks.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 162
#24

Re: LED Operating Current

03/03/2014 10:30 AM

You can buy all the LED lighting devices you want, and screw them into a light socket? How many Aggies does it take to convince you of that?

__________________
If it ain't broke, don't fix it. Just build a better one.
Register to Reply Off Topic (Score 5)
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#29
In reply to #24

Re: LED Operating Current

03/04/2014 3:10 AM

????? Who were you addressing? What are you ranting about?????

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#30
In reply to #29

Re: LED Operating Current

03/04/2014 3:28 AM

Let the man rant!! Doesn't really matter what it's about once you've had a few beers does it?

Have to say though, that your rant to sense ratio has dropped off a bit of late.

You want to pick up the pace a bit on your own ranting Andy...

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply Off Topic (Score 5)
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#31
In reply to #30

Re: LED Operating Current

03/04/2014 4:39 AM

LOL!!!!!

Haven't had a good reason lately....

I have been searching and searching and searching!!!!!!

Have I scared them all off or what???

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply Off Topic (Score 5)
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 162
#32
In reply to #29

Re: LED Operating Current

03/04/2014 9:45 AM

I was only referring to an old joke in Texas...."how many Aggies (Texas A&M Aggies) does it take to screw in a light bulb?" - It takes four: One to hold the ladder, one to put the light bulb in his mouth and hold it near the receptacle, two to pick up the ladder and rotate it.

__________________
If it ain't broke, don't fix it. Just build a better one.
Register to Reply Off Topic (Score 5)
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#33
In reply to #32

Re: LED Operating Current

03/04/2014 10:07 AM

On an international Blog, some may not understand what the hell you are talking about......

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15600
Good Answers: 981
#34
In reply to #33

Re: LED Operating Current

03/04/2014 10:58 AM

Then they should ask. It's called being the straight man in a comedic skit.

<ba doomp chek>

Did somebody ask about a henway?

__________________
"Don't disturb my circles." translation of Archimedes last words
Register to Reply Off Topic (Score 5)
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#36
In reply to #34

Re: LED Operating Current

03/04/2014 3:16 PM

I disagree, we should all start thinking internationally, it will improve CR4 further......not me me me me me....

There are many here without English or American as a first language, should we just shut the door on them?

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply Off Topic (Score 5)
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15600
Good Answers: 981
#37
In reply to #36

Re: LED Operating Current

03/04/2014 3:31 PM

I agree that frivlity should be self marked as OT but I refuse to be serious all the time.

[Nyah nyah nee nyah nya]

__________________
"Don't disturb my circles." translation of Archimedes last words
Register to Reply Off Topic (Score 5)
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#35
In reply to #33

Re: LED Operating Current

03/04/2014 10:59 AM

Here's another one...

"How many social workers does it take to change a light bulb"?

Answer: "Only one, but the light bulb has to want to change".

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply Off Topic (Score 5)
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#38
In reply to #35

Re: LED Operating Current

03/04/2014 11:02 PM

Wracked with guilt, I OTed myself...

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply Off Topic (Score 5)
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 162
#39
In reply to #38

Re: LED Operating Current

03/05/2014 9:33 AM

Yet another useless thread.

__________________
If it ain't broke, don't fix it. Just build a better one.
Register to Reply Off Topic (Score 5)
Register to Reply 39 comments
Copy to Clipboard

Users who posted comments:

Andy Germany (12); bht2010 (1); Codemaster (1); Fredski (4); James Stewart (3); justthecowboy (1); kramarat (8); redfred (3); Usbport (1); Wal (4); Yusef1 (1)

Previous in Forum: CSI Lamp Control Gear   Next in Forum: Multiple Chargers for Batteries

Advertisement