One halogen light bulb of my extractor hood was dead so I wondering if I could replace with LED solution ( example item )

To be sure about voltage type I tried with autorange multimeter DM02A but it had trouble measuring either in AC or DC mode, so I grabbed the signal using battery powered scope dso-150 and probe 10x downloading resulting waveform by serial ( attached full data xlsx ) ; it seems a pwm generated signal



Do you think that given link led will work ? From their spec it works 12/24V and consume 2W where my extractor hood connector is labeled for 20W 12V so for these parameters I'm but I don't know if the signal in the picture will be effective as an AC for the replacement led device.
Notes:
- horizontal time scale in uS
- period about 10000uS ( freq. 100Hz ) if I understood

Thank you for any directions

 

The voltage waveform shown seems to be from a switching power supply fed from non-filtered power. A far better choice would be to replace it with a suitable transformer to provide the specified voltage for whatever LEDs you buy, OR to purchase LEDs to work with your local line voltage. Either option would be effective.

 

I would guess an extractor hood is getting fairly hot extracting air from cooking ...

Leds must be kept cool ...But halogens love heat ...

Might be best just to stick with halogens , since this hood is probably not running for many hours per day.

 

You would need to investigate just how hot the hood actually gets in the area where the LED light would be. My experience has been that the halogen lights are the greatest source of heat. Consider that those filaments are white hot. But that waveform is certainly not good for the LEDs, since they must include some sort of power supply themselves. So going with the LEDs will take a different power source. That part of the project may, or not, drive the decision.

 

I tried mentioned example item and it works ; effectively I wasn't sure after reading some articles regarding LED retrofit :

• Challenges of Dimming LED Loads on ELV and MLV Transformers
  
• this explain ELVT output
• this is a project for led retrofit diy well documented

oz93666 as you stated the point is that halogen like hot temperature while led not so I measured temperature at a certain distance at beginning and after 1 hours with follow results:

START
far distance, left is LED (23C), right is HALO (50C)


near distance HALO (94C)


near distance LED (30C)


AFTER 1 HOUR
far distance, left is LED (24C), right is HALO (94C)


near distance HALO (209C)


near distance HALO just turned off (116C)


near distance LED (46C)


near distance LED just tuned off (44C)


As can be seen the alluminium case back to the extractor hub light socket works enough to maintain led in a tolerable range of temperature to avoid it for being damaged.

Visible comparision
left is LED, right is HALO and with led 2W of consumption vs 20W for HALO

 

INDEED!! MUCH Less heat, much less power used, and the secondary consequence is that it will be MUCH longer before you need to replace the LED device. The downside is that by the time a replacement is needed the device will be long obsolete. Not such a bad downside, though.

 

Unfortunately it will not work good if I change all lamp to led and a noise can be heared from the transformer,
this fact was already evaluated in one of the link referred, this one, in the initial Power source part. He solved leaving one halogen lamp in a system of 6 lamps where 5 was led type.

Initially I tought that everything was ok because testing the system with 1 led and 1 halogen the transformer worked due to load used by 1 halogen lamp with no noise.

Follows are waves for case 2HALO, 2LED

 

Attaching a 10ohm 50W rated wirewound resistor ( used for about 10W ) in parallel it works with 2 led, I measure a total current of 0.98A ; I'm not sure if this would a good solution but either in this case I would have less power consumption 2W(led)+2W(led)+10W(resistor) = 14W vs. 20W(halo)+20W(halo).

Follows waveforms: