 |
10-08-2009, 01:15 AM
|
#1
|
|
Junior Member
Join Date: Jan 2009
Location: Las Vegas
Posts: 3
|
Do LED's need a ballast?
Hello,
'Thought' I knew the answer to this question, but now I'm not 100% sure.
I have heard that LED's, if rated at correct voltage, did not need a ballast.
Is this true?
Much appreciated!!!
|
|
|
Join the #1 Electrician Forum Today - It's Totally Free!
ElectricianTalk.com - Are you a Professional Electrical Contractor? If so we invite you to join our community and see what it has to offer. Our site is specifically designed for you and it's the leading place for electricians to meet online. No homeowners asking DIY questions. Just fellow tradesmen who enjoy talking about their business, their trade, and anything else that comes up. No matter what your specialty is you'll find that ElectricianTalk.com is a great community to join. Best of all it's totally free!
Join ElectricianTalk.com - Click Here
|
Warning: The topics covered on this site include activities in which there exists the potential for serious injury
or death. ElectrcianTalk.com DOES NOT guarantee the accuracy or completeness of any information contained on this site. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task!
|
10-08-2009, 01:29 AM
|
#2
|
|
Seen your member
Join Date: Sep 2007
Location: Cornpatch USA
Posts: 10,050
|
Not that I know. They may need a resisitor, though.
__________________
This message is hidden because Forgery, Honda Racer, JackBoot, LawnGuyLandSparky, milehiwire and user 5941 are on your ignore list.
|
|
|
|
10-08-2009, 01:57 AM
|
#3
|
|
Burger Flipper
Join Date: Aug 2007
Location: Bay Area, CA
Posts: 1,763
|
most LED's need 1.5 volts DC. So: they need a rectifier, and a resistor.
~Matt
__________________
I would rather beg for forgiveness then beg for permission.
|
|
|
|
|
10-10-2009, 12:32 AM
|
#4
|
|
Junior Member
Join Date: Oct 2009
Location: Dallas, TX
Posts: 3
|
Alot of them need led drivers(ballasts)
|
|
|
|
|
10-10-2009, 02:17 AM
|
#5
|
|
Burger Flipper
Join Date: Aug 2007
Location: Bay Area, CA
Posts: 1,763
|
Quote:
Originally Posted by Elec-Tech
Alot of them need led drivers(ballasts)
|
Well, what are we specifically talking about? A LED lamp, or a single LED? He said LED, so all it needs is correct Direct Current.
~Matt
__________________
I would rather beg for forgiveness then beg for permission.
|
|
|
|
|
10-10-2009, 02:49 AM
|
#6
|
|
Junior Member
Join Date: Oct 2009
Location: Dallas, TX
Posts: 3
|
Quote:
Originally Posted by TOOL_5150
Well, what are we specifically talking about? A LED lamp, or a single LED? He said LED, so all it needs is correct Direct Current.
~Matt
|
This is true...need a little more info.
|
|
|
|
|
10-10-2009, 09:24 AM
|
#7
|
|
Seen your member
Join Date: Sep 2007
Location: Cornpatch USA
Posts: 10,050
|
Quote:
Originally Posted by TOOL_5150
Well, what are we specifically talking about? A LED lamp, or a single LED? He said LED, so all it needs is correct Direct Current.
~Matt
|
I see nothing about an LED lamp or bulb in the OP.
I just see a question about LEDs.
__________________
This message is hidden because Forgery, Honda Racer, JackBoot, LawnGuyLandSparky, milehiwire and user 5941 are on your ignore list.
|
|
|
|
|
10-10-2009, 12:00 PM
|
#8
|
|
Senior Member
Join Date: Apr 2009
Location: Canada
Posts: 784
|
I seem to recall an LED that was red with forward polarity and green with reverse polarity when you supplied it with ac it was yellow.
Or was that neon?
The mind is the first thing to go 
__________________
 Don't fight .. Play nice! 
|
|
|
|
|
10-10-2009, 12:06 PM
|
#9
|
|
Senior Member
Join Date: Sep 2007
Location: Delmarva, USA
Posts: 615
|
An LED by definition is a diode so it doesn't need a rectifier to operate.
That being said, connecting a pure LED to an AC source will cause it to "flicker" as it will only be lit half of the time.
If you use a rectifier in a power supply for an LED, that is simply part of providing a DC source to make the LED stay lit 100% of the time.
LED "drivers" as they are called are simply regulated power supplies, which may contain one or more of the following: Transformers, rectifiers, resistors, capacitors, etc. Calling that a "ballast" would be a loose translation, IMO.
__________________
-KB
Life is uncertain -- eat dessert first! 
|
|
|
|
|
10-10-2009, 03:08 PM
|
#10
|
|
idiot's idot
Join Date: Feb 2008
Location: south jersey
Posts: 63
|
I beleive the driver circuit would look something like this (full wave bridge rectifier) with the possable addition of a small dielectric filter
http://www.faqs.org/docs/electric/Semi/03263.png
added
BALLAST CIRCUITS FOR DISCHARGE LAMPS
http://www.freepatentsonline.com/3787751.pdf
certainly very similar, the only difference i see is the ballast contains a capacitor (probably as a filter) If the driver contains one as well then its pretty much identical.
those probably aren't the best examples considering one is 3 phase but you should get the idea
Last edited by gold; 10-10-2009 at 03:17 PM.
Reason: added stuff
|
|
|
|
|
10-11-2009, 04:29 PM
|
#11
|
|
Junior Member
Join Date: Jan 2009
Location: Las Vegas
Posts: 3
|
Hey All,
Good thread thus far. I'll be more specific.
Commercial office building:
- CREE LR6: http://www.creeledlighting.com/lr6.htm
- PAR30
- MR16
I understand that commercial buildings are typically wired for 277 V and Residential wired for 120 V.
So there is a CREE 240v. If office building is 277v, then would you need a ballast?
|
|
|
|
|
10-11-2009, 06:52 PM
|
#12
|
|
Senior Member
Join Date: Sep 2007
Location: Delmarva, USA
Posts: 615
|
That type of adapter would not be subject to 277V. A PAR30 bulb fixture would be connected to a 120 Volt source.
__________________
-KB
Life is uncertain -- eat dessert first!
|
|
|
|
| Thread Tools |
Search this Thread |
|
|
|
| Display Modes |
 Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
|
