LED flicker

[ianniann]

That is not the definition of a transformer. Resistors can drop voltage but they are not transformers. Transformers are AC devices. They do not rectify.

LEDs require DC. Most LED lamps of the GU10 or GU5.3 type incorporate rectifiers so they can work on AC or DC, but AC at 50/60 Hz, not AC at tens of kilohertz.

As said several times your neighbour needs a proper LED power supply.

Winston, why do you keep coming out with this crap when not only does everybody contradict you, but you can be proved wrong by the simple task of replacing a 12V lamp with an LED one?

99% of MR16 (don't even start with more of your crap, Winston) lamps include their own "driver" that will accept 12V (more or less) DC or AC and run the lamp. That 12V can come from almost anywhere, a classical transformer giving 12V AC, an "electronic transformer" giving 12V AC, or a brick/wallwart SMPS giving 12V DC. A tiny number of specialist lamps are intended only to be driven by 12V DC, sometimes requiring an external constant current supply.

The electronic transformers are by far the most common on all except the very oldest MR16 lamp installations, and they often react badly when an LED lamp is fitted. They have minimum load requirements which are typically higher than a retrofit LED lamp, so they may flicker or not light at all. They can also interact poorly with the LED drivers themselves, causing cutouts during the AC cycle that will be perceived as flicker.

You may be able to wire multiple lamps through one electronic transformer to meet the minimum load, or replace the existing transformers with drivers intended to be compatible with the new LED lamps. Or just try a different brand and it might work OK.

 

[bernardgreen]

That 12V can come from almost anywhere, a classical transformer giving 12V AC, an "electronic transformer" giving 12V AC, or a brick/wallwart SMPS giving 12V DC.

Where the item is rated as 12 volts DC (eff) the "12volts" (eff) can be 24 volts chopped 50 / 50. (*1)

As far as any filament lamps is concerned this is effectively 12 volts DC. (*2)

For electronic modules such as LED drivers the pulsed 24 volts can at best be disruptive to the stable operation of the driver and at worse destructive.


(*1) 24 v chopped 50 / 50 is quite common in halogen lamp supplies but higher voltages with different mark / space ratios have been found in some items..

(*2) the pulsing 24 volt DC will create pulsing magnetic fields around lamp filaments and this may result in mechanical vibration of the filament and early failure of the lamp.

 

[winston1]

Winston, why do you keep coming out with this crap when not only does everybody contradict you, but you can be proved wrong by the simple task of replacing a 12V lamp with an LED one?

This is what the OPs neighbour has done and found it not to work properly.

Why do you insult my intelligence when I am clearly NOT talking crap when replacing with LEDs is clearly shewn NOT to work?

 

[winston1]

[QUOTE="ianniann, post: 3892062, member: 118577"

99% of MR16 lamps include their own "driver" that will accept 12V (more or less) DC or AC and run the lamp. That 12V can come from almost anywhere, a classical transformer giving 12V AC, an "electronic transformer" giving 12V AC, or a brick/wallwart SMPS giving 12V DC. A tiny number of specialist lamps are intended only to be driven by 12V DC, sometimes requiring an external constant current supply.

[/QUOTE]

As long as that AC is not spiky and around 50/60Hz. SMPS designed for halogen lamps fail on both counts. No crap there then/

 

[winston1]

The electronic transformers are by far the most common on all except the very oldest MR16 lamp installations, and they often react badly when an LED lamp is fitted. They have minimum load requirements which are typically higher than a retrofit LED lamp, so they may flicker or not light at all. They can also interact poorly with the LED drivers themselves, causing cutouts during the AC cycle that will be perceived as flicker.

You may be able to wire multiple lamps through one electronic transformer to meet the minimum load, or replace the existing transformers with drivers intended to be compatible with the new LED lamps. Or just try a different brand and it might work OK.

Ah, so you agree then that proper LED power supplies should be used. Once again I'm not talking crap.

 

[hard-work]

Mind you I have not looked at the transformer in the ceiling space yet, would this 10-60w unit do?

https://www.mygreenlighting.co.uk/a...aJDt8j1CZipDtv0ON-cjxyBhnAPzU52C_mRoC57Xw_wcB

 

[FrodoOne]

A neighbour called me around to give a my view on their LEDs. In the bathroom there were three properly rated IP rated 12v MR18 halogen lamps. They changed them for the equivalent 5W 12v LED lamps. Total 15w.

Do you really mean MR18
That is a quite unusual lamp and not usually used with a 12 V supply.

 

[hard-work]

MR18 12v which were very common at one time, until 230v GU10 came about. The downlighter fitting is to shower room standards. I see many MR18 lamps for sale as millions of these were sold over the past 25 years or so, so replacements are needed.

 

[winston1]

Mind you I have not looked at the transformer in the ceiling space yet, would this 10-60w unit do?

https://www.mygreenlighting.co.uk/a...aJDt8j1CZipDtv0ON-cjxyBhnAPzU52C_mRoC57Xw_wcB

Transformer for 10w - 60w of low (12v) voltage halogen lighting, with terminal block output connector.

How many times do you have to be told that SMPS designed for halogen lighting is NOT suitable for LEDs? I've mentioned it five times. This is the sixth. You need a proper 12 volt power supply designed for LEDs.

 

[hard-work]

The transformer in the ceiling is 30-105w. The load is 3x 5w LED lamps = 15w.

 

[stillp]

There's your problem then!

 

[333rocky333]

or convert to mains downlights.

Bearing in mind they are not all suitable for Bathrooms

 

[333rocky333]

This is what the OPs neighbour has done and found it not to work properly.

Why do you insult my intelligence when I am clearly NOT talking crap when replacing with LED's is clearly shewn NOT to work?

Intelligence, don't make us laugh, and try sorting your own grammar before criticising others you ****.
Every post you have made hear as at least one error

 

[hard-work]

Bearing in mind they are not all suitable for Bathrooms

The lamp assembly is.

 

[winston1]

Every post you have made hear as at least one error

hear as? Oh and where is the full stop at the end of that sentence?

3 errors in one sentence must be a record.

Anyway the topic of this thread is flickering LEDs when used on a SMPS. Let's keep to it.