Dimming low voltage lights?

[ramissin]

Hi, I have two of these under cabinet lighting kits:





I want to change out the on/off switch with one of these dimmers :


Safe to do so? output is only 12 volts.

cheers.

 

[Pete999]

So the lights aint LV then.

 

[ramissin]

12 volts is high?

 

[Midwest]

You'll have to establish if the LED driver is dimmable or not. If it is the manufacturer might specify if that dimmer is compatible with their product.

 

[davesparks]

Try it and see, from the pictures it looks like that dimmer will just plug in after the switch. It will be nothing more technical than a variable resistor which you connect in series with the lights.
Due to the nature of leds you won't get a full range of dimming but it will work within certain limits.

 

[ramissin]

You'll have to establish if the LED driver is dimmable or not. If it is the manufacturer might specify if that dimmer is compatible with their product.

LED driver ? I thought this was just a simple adapter that converted 230v to 12v,
I'm not an electrician but common sense made me wonder if changing the switch to a dimmer might put strain on the adaptor when at 50%.

 

[davesparks]

You'll have to establish if the LED driver is dimmable or not. If it is the manufacturer might specify if that dimmer is compatible with their product.

That dimmer plugs in after the driver in this case so the driver doesn't need to be dimmable, it will just be a variable resistor altering the voltage across the leds.

 

[davesparks]

LED driver ? I thought this was just a simple adapter that converted 230v to 12v,
I'm not an electrician but common sense made me wonder if changing the switch to a dimmer might put strain on the adaptor when at 50%.

Driver has become the common term for any power supply used for leds whether it is a constant current driver or a simple regulated DC supply.
Yes what you have there is a simple 240V AC to 12V DC adaptor.

You won't put strain on the adaptor, that dimmer almost certainly works by increasing the resistance to dim the lights, this reduces the current flow and so reduces the load on the adaptor. It looks like it will just plug in after the switch so thee shouldn't be any need to remove the switch, and you may find that the dimmer on its own won't turn the lights off so will need to switch anyway.

 

[ramissin]

Try it and see, from the pictures it looks like that dimmer will just plug in after the switch. It will be nothing more technical than a variable resistor which you connect in series with the lights.
Due to the nature of leds you won't get a full range of dimming but it will work within certain limits.

Cheers Dave, thanks for the info, they're only £1.50 a pop so it won't hurt to try.

I'm being over cautious because they're for some cabinets at my mums house, she likes them but finds them too bright when pottering around in the early hours.

 

[Midwest]

That dimmer plugs in after the driver in this case so the driver doesn't need to be dimmable, it will just be a variable resistor altering the voltage across the leds.

Fair point, but the LED lamps may not like being dimmed, i.e. they will either dim or not.

 

[Octopus]

Hum ...... If both components cone from the sane vendor, ask them before you buy ........

Where do you plan to plug it in?

 

[ramissin]

Fair point, but the LED lamps may not like being dimmed, i.e. they will either dim or not.

I thought LEDS respected whatever voltage you threw at them.

Where do you plan to plug it in?

A plug socket.

Cheers guys, I'll try one and see what happens.

 

[Midwest]

I thought LEDS respected whatever voltage you threw at them.

I don't understand how they work, nor do I want to. But with experience installing LED luminaires, dimming them is somewhat of a dark art

Always best to check with the manufacture, to see if their product can be dimmed, and what would be a suitable compatible dimmer.

You could strike lucky, but you stand the chance of wasting time & money. But I suppose in your case there's not too much to lose, so worth a shot.

 

[Octopus]

I thought LEDS respected whatever voltage you threw at thems.

Go ahead and connect a 24v driver to a 12v led!

 

[davesparks]

I don't understand how they work, nor do I want to. But with experience installing LED luminaires, dimming them is somewhat of a dark art

dimmimg leds is much less of a dark art if you don't try to get a driver to work with a dimmer controlled mains supply. If you can give the driver a permanent supply and a control input, 0-10v for example, then it is much simpler. Alternatively a dimmer circuit which is connected after the driver circuit can also be used.

 

[ramissin]

I don't understand how they work, nor do I want to. But with experience installing LED luminaires, dimming them is somewhat of a dark art

Always best to check with the manufacture, to see if their product can be dimmed, and what would be a suitable compatible dimmer.

You could strike lucky, but you stand the chance of wasting time & money. But I suppose in your case there's not too much to lose, so worth a shot.

I contacted and got a response from the manufacturer, they say it would work but not with a full range, and would risk reducing the lifespan of the leds as they are not designed for dimming.

It's no problem, I can make use of these behind my PC monitors, I tried them before I fitted them in my mums kitchen and they put out just the right amount of backlight to prevent eye strain.

I'll buy her some more with dimmers fitted, she prefers the strip versions and pelmet anyway.

Thanks for your inputs.