LED replacement lamp won't light?

[T i m]

Hi All,

A mate just rang to see if I could shed any light on his question re why don't the 'replacement' 'low voltage' (to use comparitive terms) LED lamps work where a 'low voltage' (I assume 12V here) domestic downlighter does (I don't know any type numbers atm).

I didn't know if these 'transformers' were just that in which case they would be supplying the LED lamp with AC (so the LED might light on the right half cycle all be it dimmer)? The LED assy could have a bridge rectifier built in?

Or the transformers might be something more (electronic?) and not 'like' the different load applied by the LED lamp?

He has tested the LED lamps on 12V DC (battery) and they light up fine?

Until he brings the various bits into work for me to have a look at does anyone know what could be happening here please?

All the best ..

T i m

[Owain]

Possibly.

Very possibly. Switch-mode power supplies often have a minimum load. Early IBM PCs had a whopping big resistor hidden in one of the drive bays because of this (resistor could be replaced with a disk drive)

Or possibly they are of a slightly different base and not connectign in the lampholder properly.

Superscriptus.

Owain

[The Natural Philosopher]

Some electronic transformers will not light up unless there is SOME load on them. The LED may not be enough to do this.

[John Rumm]

You may have just answered your own question, or alternatively, like Dave said he has a SMPS rather than a real transformer and it is unable to start due to lack of load.

[T i m]

Thanks both. ;-)

Apparently he can wire the two LED lights onto one 'transformer' so I wonder if that would excert enough load?

If he let's me play with them I can measure the load current and check that against the Txfmr spec ..

All the best ..

T i m