Transformer requirement for LED lights

[Aquacrazed]

Originally Posted by calo247

no you can not just run any 12-24v supply, a 24v supply WILL fry the leds, the dimmer module has no idea what the led max voltage is... the dimmer is intended to be used with a light that comes with the appropriate power supply, and cut the voltage with 100% being running the lights at their normal undimmed output.

if you have a 24v supply on the input 100% will be 24v output and will fry the 12v rated leds. please do not get a power supply rated at more than 12v

trust me, i am an electrician

Thanks! I will get a 12v power supply rated for at least 30 watts

[mike31154]

Originally Posted by calo247

no you can not just run any 12-24v supply, a 24v supply WILL fry the leds, the dimmer module has no idea what the led max voltage is... the dimmer is intended to be used with a light that comes with the appropriate power supply, and cut the voltage with 100% being running the lights at their normal undimmed output.

if you have a 24v supply on the input 100% will be 24v output and will fry the 12v rated leds. please do not get a power supply rated at more than 12v

trust me, i am an electrician

So am I. The dimmer/timer will limit the output current to the LEDs regardless if the input voltage is 12 or 24 volts. But you don't have to trust me, get a 12 volt supply & be happy. Wonder how your LED bar hasn't fried with the 13.5 volt supply. If you have a notebook computer it most likely has a 24 volt supply with sufficient power, give that try.

[calo247]

Originally Posted by mike31154

So am I. The dimmer/timer will limit the output current to the LEDs regardless if the input voltage is 12 or 24 volts. But you don't have to trust me, get a 12 volt supply & be happy. Wonder how your LED bar hasn't fried with the 13.5 volt supply. If you have a notebook computer it most likely has a 24 volt supply with sufficient power, give that try.

there is multiple problems with this statement, first the timer doesn't really "limit" output current (as its a PWM based dimmer), the leds just draw what they need (this is why i can plug my phone into the same outlet as a fridge can use lol). and then you talk about voltage, which is completely different than current... it matters what the input voltage is there is no way that dimmer has any voltage regulation in it to reduce it to what the leds require, the only way to do this on a DC circuit is to expel it as heat, you can not use a transformer to do it, and i do not see it being able to do that with out a heatsink of some sort (even if this was the case it would be impossible for the dimmer to just determine what the leds are rated for, there for there would be some sort of way of setting the output voltage).

but what i just said does not even really matter because it says on the product page it is a PWM based dimmer so they do not use voltage reduction to get the dimming effect.

ya the 13.5v supply wont fry the strip, but i am sure a 24v one would, plug anything into double the rated voltage and let me know how that goes.

[calo247]

you could also use a switching supply to cut DC voltage but that introduces it own set of problems and would still require the output voltage to be set

[Aquacrazed]

12v it is I ordered this one: https://www.amazon.ca/gp/product/B01...?ie=UTF8&psc=1

12v 5A

[mike31154]

That should work fine. With respect to how the Dual Ramp Timer works, none of us have the internal circuitry so we can only guess at how it really functions. If you look at page 1 of the instructions, the diagram shows "12-24VDC Transformer" for both hook up configurations. There are no warnings or cautions regarding using one voltage over the other. There are plenty of DC to DC voltage converter circuits that can reduce a given voltage without the use of large heat sinks or heavy transformer coils, particularly for low power applications such as this. Could be as simple as a zener voltage regulator diode, or more complex. In any case, getting the 12 volt supply is your best bet. You can use it on your LEDs without the Dual Ramp Timer if you wish.

[calo247]

Originally Posted by mike31154

That should work fine. With respect to how the Dual Ramp Timer works, none of us have the internal circuitry so we can only guess at how it really functions. If you look at page 1 of the instructions, the diagram shows "12-24VDC Transformer" for both hook up configurations. There are no warnings or cautions regarding using one voltage over the other. There are plenty of DC to DC voltage converter circuits that can reduce a given voltage without the use of large heat sinks or heavy transformer coils, particularly for low power applications such as this. Could be as simple as a zener voltage regulator diode, or more complex. In any case, getting the 12 volt supply is your best bet. You can use it on your LEDs without the Dual Ramp Timer if you wish.

there are no warnings because they give you the list of compatible lights and they intend for you to use the power supply that is included with those lights.

if you ever find a transformer that works on DC you should notify the world, you would be a very rich man

there is no such thing as a zener voltage regulator diode, in order to get a voltage drop out of a zener diode you need to introduce a current limiting resistor (ie. heat) before it, and you would need to have so many of them as they have a very tight tolerance, so you would need differently rated one for each level of dimming you wanted.

in terms of the circuit we are not really guessing, it says its pwm based, which makes sense as it is really the most efficient


hopefully the adapter comes with the same size barrel connector, it would suck to have to lop it off

[Aquacrazed]

Ok so I got the 12v 5A adaptor and my Fluval light bar is not as bright now. It is a fair bit brighter with the 13.5V 1500ma power supply it came with.

[mike31154]

Are you running the light through the timer/dimmer or straight off the power supply?

[Aquacrazed]

The dimmer doesn't seem to have any effect, it simply seems to just pass the current. So weather I connect it through the dimmer or not, the brightness is more when I connect it with the 13.5v power supply.