POWERING LEDS - why a driver? Why not just my 12v ring main?

[TEAMYAKIMA]

Ok, as you may have guessed I am not an electronics expert!

 

I keep hearing the term 'DRIVER' and I know it's designed to power LEDS

 

I am planing to use 12v LEDS to light my layout at shows. The layout is 20ft long and 3ft wide and so I'm expecting to use 3 strips going back so 60ft of LEDS in total.

 

So I'm guessing that my normal 12v ring main around the layout won't do the job, but I have bought a 2 metre length of home lighting LEDS just for test purposes and I assume that I won't damage the LEDS by simply using  the 12v transformer in my power box for test purposes.

 

I guess I'll need to buy a driver once I determine the number of LEDS I will use eventually.

 

Thanks for any help.

[locomad2]

I use 12v LED a lot, most just need a 12v dc supply but check, some have to have correct polarity, some are 240 ac but have a small transformer inside down to 12v , some are ok for 12 ac.

 

Most small LED's require a lot smaller voltage like 3v DC I tend to use batteries for these like all LEDs they take very little current 

[Dave-5-5-7]

An LED "Driver" is really just a device for converting an incoming voltage to a lower voltage. A bit like a transformer. The downlights I used to install in houses often had a driver, 240AC in 12DC out. Some had a driver built in, others had one driver that ran several fittings. If an LED strip requires an input of 12v then 12v it needs, whether it comes from a 12v Model railway power supply or a 240v driver it doesn't matter. 

 

Edited April 3, 2021 by Dave-5-5-7

[F-UnitMad]

Might be wrong but maybe a driver is required for where LEDs can change colour and are dimmable.

[WIMorrison]

45 minutes ago, TEAMYAKIMA said:

Ok, as you may have guessed I am not an electronics expert!

 

I keep hearing the term 'DRIVER' and I know it's designed to power LEDS

 

I am planing to use 1

 

So I'm guessing that my normal 12v ring main around the layout won't do the job, but I have bought a 2 metre length of home lighting LEDS just for test purposes and I assume that I won't damage the LEDS by simply using  the 12v transformer in my power box for test purposes.

 

I guess I'll need to buy a driver once I determine the number of LEDS I will use eventually.

 

Thanks for any help.

 

You will need to confirm that any supply that you use has sufficient power to run the strips that you have bought. A 5m line of LEDS can draw 1.5A - you plan 2 which is 3A and many model railway power supplies will fail at this level of current draw.

[Nearholmer]

30 minutes ago, Dave-5-5-7 said:

An LED "Driver" is really just a device for converting an incoming voltage to a lower voltage. A bit like a transformer.

 

Most of them do a bit more than that, they provide either a firmly fixed voltage output, or a firmly fixed current output, which is necessary to get maximum life out of the LEDs. This applies whether colour and brightness control is wanted or not. If they are wanted, the driver becomes more sophisticated in order to look after those.

[Crosland]

On 03/04/2021 at 17:02, Dave-5-5-7 said:

If an LED strip requires an input of 12v then 12v it needs, whether it comes from a 12v Model railway power supply or a 240v driver it doesn't matter. 

 

Beware that a "12V Model railway power supply" can be anything but 12V. This https://www.gaugemasterretail.com/magento/gaugemaster-gmc-wm1.html for example, does NOT provide 12V DC in any meaningful sense. It simply rectifies the 16V AC giving half-wave rectified supply of 22V. Similarly the "12V" output of an analogue controller will almost certainly not be 12V.

 

To "drive" LEDs you are much better off using a well regulated power supply. These days switch mode power supplies are recommended over lumps of iron (transformers).

 

[Dave-5-5-7]

13 minutes ago, Crosland said:

 

Beware that a "12V Model railway power supply" can be anything but 12V. This https://www.gaugemasterretail.com/magento/gaugemaster-gmc-wm1.html for example, does NOT provide 12V DC in any meaningful sense. It simply rectifies the 16V AC giving half-wave rectified supply of 22V. Similarly the "12V" output of an analogue controller will almost certainly not be 12V.

 

To "drive" LEDs you are much better off using a well regulated power supply. These days switch mode power supplies are recommended over lumps of iron (transformers).

 

by 12V PSU (model railway related or otherwise) I mean 12V PSU. Not 13V, not 13,8V, not 9V, not 24V etc, a 12V power supply that will deliver 12V. It's down to the user to ensure that is the case.
All my 12V DC Power supplies deliver 12V DC within a 5% tolerance, my 24 and 48V DC, and the 55V AC (75c/s) PSUs deliver 24 and 48V DC and 55VAC respectively within a 10% tolerance because that is how I have designed them. 

 

Edited April 4, 2021 by Dave-5-5-7

[Dave-5-5-7]

On 03/04/2021 at 17:37, Nearholmer said:

 

Most of them do a bit more than that, they provide either a firmly fixed voltage output, or a firmly fixed current output, which is necessary to get maximum life out of the LEDs. This applies whether colour and brightness control is wanted or not. If they are wanted, the driver becomes more sophisticated in order to look after those.

 
Indeed, however as Teamyakima started the post with "Ok, as you may have guessed I am not an electronics expert!" I didn't want to delve to deeply into the workings of it. Sometimes less is more. 

 

[aleopardstail]

Depends what you mean by driver, typically this term means one device able to control many LEDs, this could be a simple switch, e.g. a single pole on/off switch controlling a branch of your 12v ring with all the LEDs on the switched side (with suitable resistors individually), or perhaps a few such switches controlling different sets of LEDs.

 

there is nothing wrong with this solution, indeed its both simple and effective.

 

a "driver" is more typically something like a transistor (normal or FET) to allow a low voltage/current source to switch a higher load - e.g. a micro controller, or pulse generation circuit - this has the advantage of allowing something that itself can only output a few milliamps drive much higher loads.

 

if all you want is "on/off" under manual control, go for a switch, however with very basic code (and I do mean very basic, literally a few lines) you can use an arduino or similar to control LEDs through a transistor and use a technique called pulse width modulation to both turn the LEDs on/off but also to control the brightness

 

depends what you want but in very basic terms your "driver" can be your 12v power bus and a switch (and if you want lights 'always on' you don't even need the switch), you do however need to either have the LEDs in parallel with individual resistors or to put a small number in series with a suitable resistor for each group

[AndyID]

On 03/04/2021 at 08:42, TEAMYAKIMA said:

Ok, as you may have guessed I am not an electronics expert!

 

I keep hearing the term 'DRIVER' and I know it's designed to power LEDS

 

I am planing to use 12v LEDS to light my layout at shows. The layout is 20ft long and 3ft wide and so I'm expecting to use 3 strips going back so 60ft of LEDS in total.

 

So I'm guessing that my normal 12v ring main around the layout won't do the job, but I have bought a 2 metre length of home lighting LEDS just for test purposes and I assume that I won't damage the LEDS by simply using  the 12v transformer in my power box for test purposes.

 

I guess I'll need to buy a driver once I determine the number of LEDS I will use eventually.

 

Thanks for any help.

 

Here's an article that might actually answer some of your questions.

 

https://www.ledsupply.com/blog/7-tips-before-installing-led-strip-lights/

[TEAMYAKIMA]

1 hour ago, AndyID said:

 

Here's an article that might actually answer some of your questions.

 

https://www.ledsupply.com/blog/7-tips-before-installing-led-strip-lights/

 

Many thanks for this, I have let my team know about it and we'll have a team chat about it soon 

[ColinK]

Very useful article, many thanks for the link.  I’ve been planning to install LED strips under my baseboards to light what’s below (another layout) but didn’t know where to start.  The maximum run length is something I didn’t know about and now needs to be considered.

 

All this ‘driver’ stuff confused me too - I’m a driver, but of buses, not lighting!