Pulsing led spotlight

[Thorfun]

in doing some research I bought one of these from AliExpress https://www.aliexpress.com/item/1005002156645871.html?spm=a2g0o.order_list.order_list_main.10.21ef18028Q8IPM (3W version) and one of these from Amazon to drive it https://www.amazon.co.uk/dp/B08QZ366KG?ref=ppx_yo2ov_dt_b_product_details&th=1 (12W version).

 

when I put it together the light is pulsing in a slightly irregular pattern. I've checked with a voltmeter and it's rock steady 240V at the input to the driver but the output is pulsing from 0V DC to 24VDC (ish). the driver manual says 'Min. Load recommended) 7.2W. if I disconnect the light from the driver the voltage is still pulsing. 

 

have I simply bought the wrong driver? am I not loading the driver enough? or is the driver or the light faulty?

[Temp]

14 minutes ago, Thorfun said:

am I not loading the driver enough?

 

That would be my guess. Sometimes a power supply can go unstable if its too lightly loaded. If it says minimum 7.2W and you only have 3W that might account for it. 

 

Got any 12 V car bulbs? Perhaps put two 10W bulbs in series to see if loading it up stops it flashing.

 

Only having a working range from 7.2W to 12W is pretty poor. 

 

I happen to have the 24V 60W version of this one going spare. Its new and untested. No instructions but you can have it if it helps. It says "no minimum load" in the info. 

 

https://www.amazon.co.uk/dp/B0BRQ6Y9VZ?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

If interested PM me an address and I'll stick it in the post.

 

[Thorfun]

47 minutes ago, Temp said:

 

That would be my guess. Sometimes a power supply can go unstable if its too lightly loaded. If it says minimum 7.2W and you only have 3W that might account for it. 

 

Got any 12 V car bulbs? Perhaps put two 10W bulbs in series to see if loading it up stops it flashing.

 

Only having a working range from 7.2W to 12W is pretty poor. 

 

I happen to have the 24V 60W version of this one going spare. Its new and untested. No instructions but you can have it if it helps. It says "no minimum load" in the info. 

 

https://www.amazon.co.uk/dp/B0BRQ6Y9VZ?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

If interested PM me an address and I'll stick it in the post.

 

Thanks. It’s what I thought it might be. I’ll try and add extra load and see what happens. 
 

thanks for the offer of the other driver but I just wanted something to test Chinese lights with before I purchase a load. They will all eventually be driven by a driver in my Loxone cabinet. 

[Thorfun]

anyone know how I find out if a light is constant current or constant voltage? I don't see anything on the AliExpress website. I ask as I see drivers state 'not suitable for constant current fittings' so how do I know!

[Carrerahill]

17 hours ago, Thorfun said:

in doing some research I bought one of these from AliExpress https://www.aliexpress.com/item/1005002156645871.html?spm=a2g0o.order_list.order_list_main.10.21ef18028Q8IPM (3W version) and one of these from Amazon to drive it https://www.amazon.co.uk/dp/B08QZ366KG?ref=ppx_yo2ov_dt_b_product_details&th=1 (12W version).

 

when I put it together the light is pulsing in a slightly irregular pattern. I've checked with a voltmeter and it's rock steady 240V at the input to the driver but the output is pulsing from 0V DC to 24VDC (ish). the driver manual says 'Min. Load recommended) 7.2W. if I disconnect the light from the driver the voltage is still pulsing. 

 

have I simply bought the wrong driver? am I not loading the driver enough? or is the driver or the light faulty?

Driver will be seeing that as open circuit and is pulsing the output "looking" for the load. Because of how drivers work, they need to work out what the drive voltage will be, so on startup they sort of ramp up until they detect the forward voltage of the LED (the point it starts to emit light) then they can drive it up will they get the rated current of the driver. 

 

Looking at those, I think those LED lights are just 12V because if they were say 100mA they would usually list the current not the voltage, 12V is also quite specific and few LED's will be a nice round, industry standard voltage like that.

 

 

Edited April 13, 2023 by Carrerahill

[Thorfun]

1 minute ago, Carrerahill said:

Driver will be seeing that as open circuit and is pulsing the output "looking" for the load. Because of how drivers work, they need to work out what the drive voltage will be, so on startup they sort of ramp up until they detect the forward voltage of the LED (the point it starts to emit light) then they can drive it up will they get the rated current of the driver. 

 

 

are you saying that if I leave it for a while it'll stop pulsing?

[Thorfun]

7 minutes ago, Thorfun said:

anyone know how I find out if a light is constant current or constant voltage? I don't see anything on the AliExpress website. I ask as I see drivers state 'not suitable for constant current fittings' so how do I know!

found a driver on Amazon that says:

• The led driver is a constant voltage power supply and is Incompatible for lighting products with adjustable luminosity and chromaticity, otherwise it is prone to burning. For example, dimmable LED lights and color-changing light bars.

so does this mean that as my light fitting is dimmable I shouldn't be using a constant voltage driver?

 

[Carrerahill]

Just now, Thorfun said:

are you saying that if I leave it for a while it'll stop pulsing?

No, they are incompatible, the driver behaves like that as it is ascertaining the characteristics of the LED, the fact it keeps going says they are not compatible. 

[Thorfun]

Just now, Carrerahill said:

No, they are incompatible, the driver behaves like that as it is ascertaining the characteristics of the LED, the fact it keeps going says they are not compatible. 

ok. so is this the constant current/constant voltage question I'm also trying to figure out?

[Carrerahill]

Having looked at the spec on AliExpress is says the input voltage is 12-24VDC - get a DC supply in that region capable of the wattage you need (add them all up for total wattage) and it will work.

 

 

[Thorfun]

Just now, Carrerahill said:

Having looked at the spec on AliExpress is says the input voltage is 12-24VDC - get a DC supply in that region capable of the wattage you need (add them all up for total wattage) and it will work.

 

 

I'm so confused. I thought I HAD bought a 12-24VDC driver! 🫠

[Carrerahill]

1 minute ago, Thorfun said:

ok. so is this the constant current/constant voltage question I'm also trying to figure out?

Their is nothing to suggest they are CC. If they were a current would be listed somewhere. 12-24DC. Hook one up to your car cigarette lighter or any other 12-24DC power supply you have and it will work. 

[Carrerahill]

Just now, Thorfun said:

I'm so confused. I thought I HAD bought a 12-24VDC driver! 🫠

Maybe you have, but did you not say there was a minimum load?

[Thorfun]

1 minute ago, Carrerahill said:

Maybe you have, but did you not say there was a minimum load?

ahh...yes. it did have a minimum load. sorry. so confused like I said. I'll just purchase another 12-24VDC driver that doesn't have a minimum load and see how I get on!

 

might just purchase this instead though:

 

https://www.amazon.co.uk/110-240V-Massager-Essential-Diffusers-5-5x2-1mm/dp/B09YQYJ4B8/ref=sr_1_6?keywords=24v+power+supply+led&qid=1681386910&sprefix=24v+p%2Caps%2C90&sr=8-6

 

I presume that'll do the job to test single lights?

[Carrerahill]

Right, I have just looked at the transformer you bought, it is a half amp 24VDC power supply.

 

How many of the little LED lights do you have? Are you overloading it? They state they are 1W/3W - LED's are funny, I would say at 24V they will be 3W as they are pulling more current as the forward voltage goes up, so do you have too many on it and thus are overloading it?

[Carrerahill]

4 minutes ago, Thorfun said:

I presume that'll do the job to test single lights?

Should do.

 

Do you have any old power supply that is output DC between 12-24V? Favourite of mine back in the day was a Hornby trainset supply. Used to use it for all sorts before I got my lab power supply.

 

 

 

 

 

Edited April 13, 2023 by Carrerahill

[Thorfun]

1 minute ago, Carrerahill said:

Right, I have just looked at the transformer you bought, it is a half amp 24VDC power supply.

 

How many of the little LED lights do you have? Are you overloading it? They state they are 1W/3W - LED's are funny, I would say at 24V they will be 3W as they are pulling more current as the forward voltage goes up, so do you have too many on it and thus are overloading it?

not overloading for sure. I only have one led light on it at the moment. I am just researching and testing at the moment to see if it's worth buying these lights direct from China as they're stupidly expensive over here! thought I'd buy a couple to test (others are en-route). the one I currently have is the 3W model, they do offer a 1W model I just wanted to see if 3W is too much for what we're illuminating as part of the research. photo of sticker below:

 

 

I can only presume that I've not hit the minimum load.

 

3 minutes ago, Carrerahill said:

Should do.

 

Do you have any old power supply that is output DC between 12-24V? Favourite of mine back in the day was a Hornby trainset supply. Used to use it for all sorts before I got my lab power supply.

 

 

 

 

 

I'll see what I have. problem is most of my stuff is in boxes in the loft of the existing bungalow or basement of the new build so hard to get to and find stuff!

 

[Carrerahill]

1 minute ago, Thorfun said:

not overloading for sure. I only have one led light on it at the moment. I am just researching and testing at the moment to see if it's worth buying these lights direct from China as they're stupidly expensive over here! thought I'd buy a couple to test (others are en-route). the one I currently have is the 3W model, they do offer a 1W model I just wanted to see if 3W is too much for what we're illuminating as part of the research. photo of sticker below:

 

 

I can only presume that I've not hit the minimum load.

 

I'll see what I have. problem is most of my stuff is in boxes in the loft of the existing bungalow or basement of the new build so hard to get to and find stuff!

 

Ah, didn't read the 1/3W was different models, I thought they were being typically Chinese about the spec of the chip at different voltages. Those are suggesting to be 95Lm per watt, so 285Lumen.

 

 

[Thorfun]

2 minutes ago, Carrerahill said:

Ah, didn't read the 1/3W was different models, I thought they were being typically Chinese about the spec of the chip at different voltages. Those are suggesting to be 95Lm per watt, so 285Lumen.

 

 

yeah. I also bought a 1W model from different seller to compare the wattage/lumens etc. these are so cheap compared to UK bought ones that I figured I'd lose so little doing this testing it was worth it. at the end I should have a good idea as to what lumens give me what in real life so can make an informed decision about what to buy for the final lights.

[Carrerahill]

1 hour ago, Thorfun said:

yeah. I also bought a 1W model from different seller to compare the wattage/lumens etc. these are so cheap compared to UK bought ones that I figured I'd lose so little doing this testing it was worth it. at the end I should have a good idea as to what lumens give me what in real life so can make an informed decision about what to buy for the final lights.

What are you going to light with them? 

 

I know what you mean about cost, I bought 6, circa 40mm downlights with white bezels about 7 years ago for a plasterboard shelf detail I built down each side of a chimney breast and they were about £40 Ea. at the time. 

[Thorfun]

48 minutes ago, Carrerahill said:

What are you going to light with them? 

 

I know what you mean about cost, I bought 6, circa 40mm downlights with white bezels about 7 years ago for a plasterboard shelf detail I built down each side of a chimney breast and they were about £40 Ea. at the time. 

 

most likely a WhiteWing driver in our Loxone cabinet controlled by DMX with Loxone. so centralised driver.

 

found some mini-ground mounted spots from Collingwood. £65+VAT! this one from China cost me £10 and is smaller. 

Edited April 13, 2023 by Thorfun

[Pocster]

Buying China stuff always a bit maybe / maybe not work . I always fit dimmers to all lights now ( controlled by HA ) then the issue of burning my retina not a problem.

I like buying stuff off AliExpress - always a bit “ lucky dip “ - but as so cheap - why not .

[Radian]

5 hours ago, Thorfun said:

so does this mean that as my light fitting is dimmable I shouldn't be using a constant voltage driver?

 

I couldn't see where it says it's 'dimmable'?

The 12V-24V spec means it has a buck regulator inside that maintains a constant LED current over the 12-24 volt range. Dimming can only be done with a PWM drive signal but that's not necessarily going to be nice to the buck regulator. Generally these are non-dimmable.

[Temp]

The data for the LED on Aliexpress is confusing. It could be 12V DC, 12V AC or 12-24V DC. However one of the photos is a diagram showing how multiple LED are connected. This shows a 12V DC transformer. It also shows the LED wired in parallel.

 

So I think it's most likely to require a 12V DC voltage (possibly 24V DC) and very unlikely to be a constant current type. 

 

With a constant current type LED you would either use one driver per LED or possibly wire multiple LED in series not parallel.

[Adrian Walker]

You might find that the power supply is a very simple circuit with not much more that a bridge rectifier giving a very poor quality DC output. I would take it apart and have a look at the circuit.