Incandescent and LED lighting

Joined
3 Nov 2006
Messages
28,088
Reaction score
3,284
Location
Bedfordshire
Country
United Kingdom
The most common sources of power for electric lamps are :-

(a) Low Voltage AC mains supply ( 100 to 230 volts ) at 50 Hz

(b) Extra Low Voltage AC supply ( < 100 volts ) from a magnetic transformer at 50Hz

(c) Extra Low Voltage AC supply from a Switch Mode Power Supply

(d) Extra Low Voltage DC supply from a Switch Mode Power Supply

(e) Extra Low Voltage DC (eff) supply from a Switch Mode Power Supply

(f) Smooth Extra Low Voltage DC from a battery

A Switch Mode Power Supply with an output rated at 12 v DC (eff) will produce an output that if supplied to an incandescent lamp would have the same heating effect as a smooth 12 volt DC supply from ( for example ) a battery.

The output voltage from a Switched Mode Power Supply rated as 12 v DC (eff) fluctuates at high frequency but averages out to be 12 volts DC. This may be 24 volts on for half the time and then off for half the time . or 36 volts on for 1/3 of the time and then off for 2/3 of the time. This type of voltage regulation is known as Pulse Width Modulation ( PWM )




Incandescent lighting

Incandescent lamps are a metal filament in a glass or quartz envelope filled with an inert gas that allows the filament to become white hot without burning and thus emit white light.

The filament is heated by passing an electric current through it. The amount of current is determined by the voltage applied to the ends of the filament and the electrical resistance of the filament.

An incandescent lamp is self contained and needs no external device to control the current through it. Provided the voltage applied to the ends of the filament is equal to or less than the lamps rated voltage then the lamp will not be damaged. It can be a DC voltage, an AC voltage or a DC (eff) voltage. A DC (eff) supply with large fluctations in output voltage at high frequency may cause the filament to vibrate ( electro-magnetic effect ) and thus reduce the mechanical life span of the lamp.

LED Lighting

LED lamps use Light Emitting Diodes to produce light. The LED itself is a semiconductor diode that produces light when a current flows through it. It has no effective internal resistance and therefore cannot control the current that passes through it when a voltage is applied.

A semiconductor diode also has a threshold voltage. If the voltage applied to the diode is less than the threshhold ( typically 3 volts for a "white" LED ) then the diode will not pass any current and not produce any light. When the applied voltage is greater than the threshold the diode becomes zero resistance and will pass as much current as the power source can provide. Without some form of current control the diode will be destroyed+

An LED lamp consists of one or more LEDs and a means to control the current that passes through them

The means to control the current can be :->

(1) a simple resistor for lamps that operate from a stable DC supply

(2) an electronic LED driver that produces a controlled DC current appropriate for the LED(s) in the lamp.

Electronic LED drivers use Switch Mode Current Control to regulate the current supplied to the LED(s)

The electronic LED driver built into the lamp has to be compatible with the type of power source that is supplying the lamp if it to properly control the current it supplies to the LED element(s).

The current control circuit of all LED drivers requires a DC power source. LED drivers intended for use on AC supplies will include a rectifier to produce DC power and a capacitor to provide some smoothing of the DC power supplied to the current control circuit.

Dimming and Pulsing LED elements

An LED element can be dimmed by reducing the DC current driven through it.

An LED element can be made to appear brighter to the human eye by driving pulses of high current through it. The pulses can be several time the rated current provide the gap between them give an average current less than the rated continuous current. An LED element pulsing at 50 pulses per second or faster will appear in the human eye to be continuous lit.

Pulsing can produce a bright light with much reduced power consumption for warning beacons. It should not be used for work lights as a strobing effect on moving items will occur.


Compatibility Issues

The voltage on the terminals of the LED element will be about 3 volts . This is determined by the LED element and not by the amount of current driven through the LED element by the LED driver. A driver can drive current through several elements connected in series, the number of series connected element is determined by the maximum voltage the driver can produce on it's terminals while still regulating the current.

The three most common type of LED lamp are

(a) Battery operated lamp which has just a driver and element(s)

(b) ELV lamp which has rectifier and driver and element(s)

(c) Mains lamp which has voltage reduction and rectifier and driver and elements




upload_2018-7-4_11-25-10.png





Some ELV operated lamps will not accept a ELV DC supply.

When an ELV lamp is supplied with ELV AC 50 Hz reduced from mains voltage by a magnetic transformer there are few if any compatibility problems. Some ELV Operated lamps will not operate on a DC supply

Items labelled as "electronic transformers" are Switch Mode Power Supplies

An electronic transformer does not produce an ELV AC supply at 50 Hz hence when the ELV supply is from an electronic transformer compatibilty cannot be assured and the risk of unstable operation of the driver is high.

The majority of electronic transformers produce a fluctuating DC voltage that averages out to the rated voltage. The fluctuations can include voltage spikes large enough to damage the electronics in the driver. The fluctuations can disturb the operation of the driver resulting in unstable control of the current driven through the LED element.

An item labelled as an LED driver should not be used to supply power to any type of lamp other than one or more LED elements connected in series.

An LED driver is designed to drive ( force ) it's rated current through what ever is connected across it's output terminals. The voltage on the LED driver's output will be set such that the rated current is flowing out of the driver and through the item connected to it. If the item being supplied normally takes less than the LED driver's rated current then the LED driver will increase the voltage on it's output until the rated curren is flowing. This high voltage and excessive current will damage the LED driver inside the lamp.
 
Sponsored Links
1) Low Voltage does not begin at 100V.

2) Whether you like it or not, there ARE products out there which are called Constant Voltage LED drivers, and your warning at the end does not apply to them.
 
2) Whether you like it or not, there ARE products out there which are called Constant Voltage LED drivers, and your warning at the end does not apply to them.

They are incorrectly labelled then aren't they? If someone incorrectly calls a pig a cow, that means they are ignorant. It does NOT mean that pigs are cows.
 
If someone wants a pig and finds one for sale and it's called a cow, if he buys it he will get a pig.


Whether you like it or not, there ARE products out there which are called Constant Voltage LED drivers.

You cannot change the reality that people will encounter them for sale by pretending that reality is how you wish it were rather than how it is.

Reality does not work like that.
 
Sponsored Links
If someone wants a pig and finds one for sale and it's called a cow, if he buys it he will get a pig.


Whether you like it or not, there ARE products out there which are called Constant Voltage LED drivers.

More to the point if someone wants a cow and buys one only to find it is a pig he will *issed off.

there ARE products out there which are INCORRECTLY called Constant Voltage LED drivers.
 
You cannot change the reality that people will encounter them for sale by pretending that reality is how you wish it were rather than how it is.

The reality that you promote is a false "reality" that should be corrected to reduce the amount of confusion and damaged equipment that it causes.

there ARE products out there which are called Constant Voltage LED drivers

An LED cannot be driven by a Constant Voltage LED driver without the LED being at significant risk of being damaged by over current. (*)

An LED lamp with integral driver can be supplied from a constant voltage source


(*) there are LED elements that have a resistive junction incorporated into the semi-conductor assembly. They can be connected to a 3 volt DC supply and were developed for mass production of long low brightness strings of LED.
 
there ARE products out there which are INCORRECTLY called Constant Voltage LED drivers.
Then go and fix the problem at source.

Do not attempt to fix it by telling people things which are untrue because you wish they were, for that will not work.
 
The reality that you promote is a false "reality" that should be corrected to reduce the amount of confusion and damaged equipment that it causes.
Then go and fix the problem at source.

Do not attempt to fix it by telling people things which are untrue because you wish they were, for that will not work.


An LED cannot be driven by a Constant Voltage LED driver without the LED being at significant risk of being damaged by over current. (*)
That will come as surprising news to anybody who has ever used a constant voltage source such as a battery to power LEDs.


An LED lamp with integral driver can be supplied from a constant voltage source
And that remains true when that source is described as a constant voltage driver.

Basically, Bernard, will you just (£$&%*(%#@ GET OVER IT!

You are not, absolutely not, going to rid the world of products whose labelling you do not like by pretending that they do not exist, or by deliberately misleading people by giving them "advice" which is distorted by the lens of your desire.


Looks like this manufacturer labelled the product correctly,

View attachment 125684
 
An LED cannot be driven by a Constant Voltage LED driver without the LED being at significant risk of being damaged by over current. (*) .... An LED lamp with integral driver can be supplied from a constant voltage source.
Indeed - and I would say that we have here another potentially troublesome sloppy use of terminology - since a high proportion of people (including manufactures and retailers/wholesalers) are using "LED" to refer to a "LED lamp" (with integral driver) - leaving us having to qualify "LED" if we want to refer to what "an LED" originally was (i.e. an 'LED element').

We wouldn't dream of calling an incandescent lamp/bulb (aka "a filament bulb/lamp") "a filament", so I don't know why this misuse of "LED" arose.

Kind Regards, John
 
Bernard
Well done on starting writing.

1) Noticed a typo in following where I feel heating would be better as being lighting (as the article is about lighting):
"A Switch Mode Power Supply with an output rated at 12 v DC (eff) will produce an output that if supplied to an incandescent lamp would have the same heating effect as a smooth 12 volt DC supply from ( for example ) a battery."

2) Symbol for "volts" is normally capital "V" not "v".

SFK
 
Indeed - and I would say that we have here another potentially troublesome sloppy use of terminology -
As you said, it's sloppiness, but this is what leads to your 'evolution of the language'.
It is caused by inappropriate abbreviations and ignorance.

Even Winston's 'transformer' must be an abbreviation from the original inventor's longer description or name of the original.

Even he presumably does not go into the wholesaler and merely say "A transformer please" - or Bernard "A driver please" - and expect to get exactly what he wants; further description is required so arguing that one word means one thing is fatuous.

There are numerous examples other than electrical items.
From the Police's "A male was seen running..." to "homophobic" which actually means either having an irrational fear of the same or a group of people with the same phobia - any phobia. This is because of another inappropriate abbreviation; "homo" is an inappropriate abbreviation of a homosexual person - usually a male person for some reason - as it just means same. That's from the Greek; the same word in Latin means simply man - any man.
 
As you said, it's sloppiness, but this is what leads to your 'evolution of the language'. It is caused by inappropriate abbreviations and ignorance.
In this case, yes. As you know, I have no problem (quite the opposite) with 'evolution of language', per se - but I do have a problem when it leads to ambiguity.
Even Winston's 'transformer' must be an abbreviation from the original inventor's longer description or name of the original.
If you are right about the "original inventor's longer description", then this is again an example of 'sloppy abbreviation' leading to ambiguity.
... "homophobic" which actually means either having an irrational fear of the same or a group of people with the same phobia - any phobia.
Again, ambiguity due to (maybe 'sloppy') abbreviation - to be unambiguous, it clearly should be 'homosexual phobia' or 'homosexualityphobia'. In this case it is less of a problem, since the literal definitions you propose would not be things for which people would normally need a word, and the intented meaning is almost universally un derstood. Mind you, there are plenty of other homoXYZ words that it could be an abbreviation for.

Abbreviations are fine if their meaning is clear from context. A good few abbreviations used and understood by electricians in an electrical context would have another meaning, or possible meaning, to me if presented without context (hence potentially ambiguous). Even within fields there can be ambiguities in the absence of context - just a few years back, phoning an electrician and saying that "you wanted/needed a PIR" would have been ambiguous.

"Homo...." is, of course, as you imply, quite a problem in general, because of origins of language, rather than evolution of language. Since the word/prefix had totally different meanings in Latin and Greek, one either has to know which of those languages an English word was derived from, or (much more commonly) simply learn what the English word means. There are many other examples of this, due to English having been derived from several other languages (and then 'evolved') - we've discussed, for example, the "in" of "inflammable" - which certainly causes some people a lot of confusion. However, other perhaps than with Esperanto, this is an inevitable problem of almost any modern language.

Kind Regards, John
 
Noticed a typo in following where I feel heating would be better as being lighting (as the article is about lighting):

I used heating effect because the current heats the filament, light is only produced as a "by-product" of the filament being hot enough to emit light.
 
Noticed a typo in following where I feel heating would be better as being lighting (as the article is about lighting):
I used heating effect because the current heats the filament, light is only produced as a "by-product" of the filament being hot enough to emit light.
How about simply

... will produce an output that if supplied to an incandescent lamp would have the same effect as a smooth 12 volt DC supply from ...
 
They are incorrectly labelled then aren't they? If someone incorrectly calls a pig a cow, that means they are ignorant. It does NOT mean that pigs are cows.
It means my 4 year old daughter thinks it's funny to wind up her mother. No fun giving them right name.

We have three basic ways to light a house using electric.
Tunsten which can be further divided into with and without super hot quartz.
Fluorescent which can be further divided into inductance control and electronic control.
Then we have LED, again we could simply devide into capacitive and electronic control, however there are also specials. But capacitive control is A.C. 50 Hz only and can be dimmed, but electronic has so many options, AC, DC, fixed voltage, variable voltage (10-30) control built into the bulb package, control outside the bulb package, control split between the two.

Buy a tunsten or fluorescent and it is clearly labelled what you have, voltage, wattage, ac, DC, electronic, quartz, but the LED everything is a secret if your lucky it may say 50 Hz 12 volt, but even then we don't know if it has to be 50 Hz or will it also work on DC and kHz as long as latter able to supply low current.

What is 12 volt? is it 11.8 to 12 volt or 10 to 30 volt? So if I renew my caravan lamps with LED with the 13.8 volt make them fail or not?

Even as electricians it is guess work, at least for extra low voltage, OK for 230 vac they are simple enough, but extra low voltage is a mine field.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top