LED dimmer warning

[RichardS]

That all does seem very strange. It takes a bit of clever circuitry to boost a DC voltage into a higher DC voltage so how a device which is designed to reduce the input DC voltage could erroneously double the voltage seems a rather odd.

Richard

 

[GHA]

Without stripping it to see can't give a more positive answer but depending on what's inside it is not impossible.

Quick google and it looks impossible, assuming this is the same unit, same case and labeling anyway. Good cheap stuff and very nasty cheap stuff on ebay, just plugging it in without checking is a bit on the trusting side, thankfully gigabytes of teardowns and reviews of lots of it on youtube and only takes a moment to stick a meter across it.

Hard to see how what's basically a very fast switch could boost the voltage with no inductor anywhere.

>>

 

[Lon nan Gruagach]

Who the hell do you think you are ?

I didn't ask for your help and i don't need it either. I'm perfectly capable of working a multimeter, thanks.

Quick google and it looks impossible, assuming this is the same unit, same case and labeling anyway. Good cheap stuff and very nasty cheap stuff on ebay, just plugging it in without checking is a bit on the trusting side, thankfully gigabytes of teardowns and reviews of lots of it on youtube and only takes a moment to stick a meter across it.

Hard to see how what's basically a very fast switch could boost the voltage with no inductor anywhere.

>>

It won't boost the voltage under load, you may get some very low power boost from parasitic inductance when connected to a multimeter.

A sensible test would have been to wire the LEDs directly to the supply. That would have very quickly shown that the dimmer wasn't faulty.

 

[seadog30]

Having had a chance to get back onboard and finish testing, the issue was that the supply on the boat was indeed 24v, although it was clearly marked as being 12v. The 27v would be due to the mains charger being on.

To answer another question that was raised, some devices will produce voltages higher than the input voltage, for instance, i have a variable converter that runs my 19v laptop from the 12v input.

These things are advertised with varying descriptions and this one came with data. Advertising it as a LED dimmer with 12-24v input is misleading, one would tend to assume there would still be a maximum output of 12v, or it will burn the LEDs out in a short time.

I still think it's a good bet to check the output of any cheap Chinese electrics.

Paul, I have to agree 100% with you.

I spent my career in electronics purchasing and inthe latter years subcontracting manufacturing to the far east. I recall one project where our UK company designed a "smart" Power Supply / charger. We manufactured prototypes, circuit diagrams, test specs, parts list etc. I sent this package to an already established contractor in China for the manufacture of production samples. I visited the factory to inspect the production samples and do a production systems Quality check. The sample test results were not quite as expected, then I noticed that the "smart" chip that we had specified as Intel manufacture did not have a manufacturers name on it . I asked the production director to prove that the parts were as per spec. he was confused and then asked me to confirm "what I wanted them to have printed on the chips".

It was quite clear that some subcontractors in the east have a different view to copyright and specifications.

Paul you can not be to carefull with safety, test it as you sugest or pay more to buy from a reliable source.

Good luck - Phil

 

[Hoolie]

OK chaps, calm down. It's a non-problem as the device is just a PWM dimmer and on its maximum setting will output the input volts. So 27v in = 27v out. LEDs that expect 12v will be seriously unhappy if that's the setup ... ...

 

[PaulRainbow]

Paul, I have to agree 100% with you.

I spent my career in electronics purchasing and inthe latter years subcontracting manufacturing to the far east. I recall one project where our UK company designed a "smart" Power Supply / charger. We manufactured prototypes, circuit diagrams, test specs, parts list etc. I sent this package to an already established contractor in China for the manufacture of production samples. I visited the factory to inspect the production samples and do a production systems Quality check. The sample test results were not quite as expected, then I noticed that the "smart" chip that we had specified as Intel manufacture did not have a manufacturers name on it . I asked the production director to prove that the parts were as per spec. he was confused and then asked me to confirm "what I wanted them to have printed on the chips".

It was quite clear that some subcontractors in the east have a different view to copyright and specifications.

Paul you can not be to carefull with safety, test it as you sugest or pay more to buy from a reliable source.

Good luck - Phil

Thanks Phil.

 

[PaulRainbow]

OK chaps, calm down. It's a non-problem as the device is just a PWM dimmer and on its maximum setting will output the input volts. So 27v in = 27v out. LEDs that expect 12v will be seriously unhappy if that's the setup ... ...

You're right in one way, it is just a PWM device and it's working how you'd expect a PWN device to work. My assumption the the supply labelled 12v was actually 12v was wrong and it turned out to be a 24v supply. But, these devices are marketed with the implication that they are 12-24v input with 12v outputs, suggestion that they are DC-DC converters and that they are therefore suitable for running 12v LEDs from a 12v or 24v supply.

So although my original thought that this was a faulty device was incorrect, the warning to check the output of cheap Chinese electrics/electronics still stands. Previous threads regarding cheap USB sockets would reinforce that advice.

 

[Hoolie]

The device spec is "imprecise". It could be inferred that the output voltage could be up to 24v from the power rating:- Output power: 5V <40W, 12V <96W, 24V <192W . But, as you say, with these cheap devices nothing can be assumed and they should be properly checked before use.

 

[A1Sailor]

Who the hell do you think you are ?

I didn't ask for your help and i don't need it either. I'm perfectly capable of working a multimeter, thanks.

Can you check input voltage with a multi-meter? Or perhaps get a qualified/experienced marine electrician to do it for you?

 

[Alex_Blackwood]

So although my original thought that this was a faulty device was incorrect, the warning to check the output of cheap Chinese electrics/electronics still stands. Previous threads regarding cheap USB sockets would reinforce that advice.

Paul, You won't be the first one to have made that sort of assumption. Stand up the engineer who hasn't!

 

[Lon nan Gruagach]

The device spec is "imprecise". It could be inferred that the output voltage could be up to 24v from the power rating:- Output power: 5V <40W, 12V <96W, 24V <192W . But, as you say, with these cheap devices nothing can be assumed and they should be properly checked before use.

You mean like the arseumption that it was meant to also be a buck/boost converter specifically for 12V LEDs, even though there is nothing to even imply that in the device listing. Whereas it clearly states out current and power for a range of input voltages.

 

[lw395]

Now then, pin back yer lug oles and prepare to learn a thing or 2.
Let's start with the device. If it is indeed the same functionally as the one in the link..
It is no more than a power supply chopper, it actives dimming by pulse width modulation.
The control side needs at least 5V and not more than 24V. The output side will only chop the incoming supply, it will not boost or convert the voltage. The output circuit has a maximum capability of 8A, thus he specification that it can control 40W from a 5V supply, 92W from 12V and 192W from 24V.

So, where did 27V come from and is it significant?
Being a square wave chopper any parasitic inductance in the circuit could easily provide 27V into a high impedance such as a multimeter. When any significant load is applied a more sensible and relevant reading would be obtained.

So why bother with all this electronic mumbo jumbo... If I am right about the device, it's function and operating principal (and, given my knowledge of electronics and chinglish, I am right) then there is another problem that won't be solved by removing the unit.

Which all comes back to was the 27V measured under load? And instead of misguided glib cheeky replies, just answer the question if you want any help with not misdiagnosing the problem and misleading the forum about the dimmer.

Clearly you know very little about switching powers supplies in general or LED drivers in particular.
There are an awful lot of buck-boost circuits out there.
Many LED drivers regulate the current, not the voltage.
Many are intended to drive long strings of LEDs in series.

There are plenty around which are intended to drive '12V' led tapes.

 

[PaulRainbow]

Can you check input voltage with a multi-meter? Or perhaps get a qualified/experienced marine electrician to do it for you?

See if you can find a grownup to read the whole thread for you, in particular, post #20

 

[PaulRainbow]

You mean like the arseumption that it was meant to also be a buck/boost converter specifically for 12V LEDs, even though there is nothing to even imply that in the device listing. Whereas it clearly states out current and power for a range of input voltages.

If you read the thread properly, instead of shooting your mouth off, you will see that the device was supplied with no documentation, i din't buy it, a friend did.You will also see that the Ebay link i posted was an example of the style of the device, it actually came from Amazon. From post #1 :

He'd purchased the dimmer from a seller on Amazon, looked like this one on Ebay

So the drivel you typed above is just that, drivel, as usual for you.

 

[A1Sailor]

Can you check input voltage with a multi-meter? Or perhaps get a qualified/experienced marine electrician to do it for you?

See if you can find a grownup to read the whole thread for you, in particular, post #20

So can you check input voltage with a multimeter? On the assumption that you can, why didn't you?

Edit: Apologies. Just seen your website - you specialise in 12v electrics so 24v was an unexpected challenge...

Based in the Ipswich area, i cover Suffolk and Essex, but can travel to wherever you are. With over 40 years experience of all types of engines, from small two strokes to large diesels, 12v electrics, electronic systems and general engineering you can be assured that any work carried out will be to the highest standards. I am a boat owner too, so i know my way around a boat and have a good understanding of what works well onboard. Check out the “Services” page to see what i am able to do for you. For a quality, reliable service, without the “marine” price tag give me a call or fill in the contact form and i’ll get back to you ASAP.

 

[petem]

Having read this thread, it gives no reason for NOT using cheap Chinese electrical parts. I know that my colleagues on the Mobo forum use the cheap Chinese DROK 24->24v droppers on their £million boats all the time with no issues.

It seems that the OP has made some errors...

1) assuming that the boat was 12v when in fact it was 24v. Surely the size of the boat would have alerted him to it possibly being a 24v system?
2) assuming that the dimmer would ensure a 12v output (why he would assume this I do not know)
3) using LED's that don't incorporate a voltage dropper / regulator (which would have worked with 12v or 24v supplies).

Incidentally, my third point above is relevant for boaters running 12v LED's even on a 12v boat. It is important to use a dropper or LED's that can cope with higher voltages as even 13.5v can cause them to run hot and shorten their lives.

 

[PaulRainbow]

Having read this thread, it gives no reason for NOT using cheap Chinese electrical parts. I know that my colleagues on the Mobo forum use the cheap Chinese DROK 24->24v droppers on their £million boats all the time with no issues.

I didn't say don't use them, i said make sure you check that they are doing what you think/they say they should be doing. If your mobo buddies are fitting cheap DC-DC converters without checking them some of them will be in for a surprise one day. I've seen cheap Chinese USB sockets outputting full 12v before now, for instance.

It seems that the OP has made some errors...

1) assuming that the boat was 12v when in fact it was 24v. Surely the size of the boat would have alerted him to it possibly being a 24v system?

I made no such assumption. I am fully aware that the boat is primarily 24v, as are many of the boats i work on. I'm also aware that it has some 12v circuits, the supply i used was clearly marked thus and was adjacent to a 12v cigarette socket.

2) assuming that the dimmer would ensure a 12v output (why he would assume this I do not know)

You see many 24v LED lights ?

3) using LED's that don't incorporate a voltage dropper / regulator (which would have worked with 12v or 24v supplies).

I wasn't using anything, the LEDs had been fitted by the boat owner, the dimmer had been fitted by the boat owner. I was simply crimping some connectors for a friend. I had seen the LEDs he had bought and advised him against using them and against using cheap shite remote dimmers. He fitted them anyway. He's one of you mega bucks mobo buddies, by the way.

Incidentally, my third point above is relevant for boaters running 12v LED's even on a 12v boat. It is important to use a dropper or LED's that can cope with higher voltages as even 13.5v can cause them to run hot and shorten their lives.

The device to which you refer is a DC-DC convertor, i've fitted numerous ones to all manner of electronics to ensure a stable supply. The LEDs i supply and fit for customers have circuitry to ensure a stable voltage, can be wired in either polarity and have heatsinks to ensure cool running and long life.

 

[petem]

I've seen cheap Chinese USB sockets outputting full 12v before now, for instance.

They'd be the ones that you assume would incorporate a voltage dropper! Which kind of reinforces my point that you should assume that a component will drop the voltage unless is explicitly says so.

Anyhow, I'm not deliberately trying to be a smart arse and you have a little of my sympathy if the supply was marked as 12v. And I certainly agree that a multimeter is your best friend when doing this sort of stuff on a boat.

 

[Jabs]

Who the hell do you think you are ?

I didn't ask for your help and i don't need it either. I'm perfectly capable of working a multimeter, thanks.

At the risk of being controversial, maybe a check with the multimeter on the incoming would have saved a lot of grief on this post!

Tony

 

[GHA]

At the risk of being controversial, maybe a check with the multimeter on the incoming would have saved a lot of grief on this post!

Tony

Double checking you didn't mess up before posting would been a good idea too

Back to ebay, another handy toy to have onboard is an adjustable DC constant voltage/constant current supply, set the amps low when testing anything suspect -

https://www.ebay.co.uk/itm/DC-38V-6...791394&hash=item41df385803:g:ek4AAOSw4nZay1k1

buck only around cheaper