12v dc smoother

[LMS_LNER_SR_GWR_fan2004]

Hi all,

 

apologies if this is in the wrong section but I am building my first layout and I recently bought a layouts4u level crossing. However it requires a smoothed 12v dc current and I was wondering if it is possible to connect it to the bus wire? 

 

Best regards, Matthew

[PatB]

I think I'd want to put a bridge rectifier, a big capacitor and a voltage regulator between a DCC bus and anything requiring a smoothed 12V DC supply. Plenty of circuit diagrams on the web for suitable arrangements. Or maybe an appropriate accessory decoder.

[WIMorrison]

A rectifier with a smoothing capacitor and a 12v buck regulator will give you the supply you need from the DCC bus

Edited June 8, 2019 by WIMorrison

[Junctionmad]

You don’t need a big capacitor because the frequency is high and it’s a square wave 

 

in fact you don’t need one at all really 

[melmerby]

Why not just buy a small 12v supply and forget the DCC bus altogether?

[PatB]

1 hour ago, Junctionmad said:

You don’t need a big capacitor because the frequency is high and it’s a square wave 

 

in fact you don’t need one at all really 

Well, no, but they're cheap and won't do any harm, and give you what is, in effect, a universal smoothed 12V supply, rather than one tied to a particular power source. 

1 hour ago, melmerby said:

Why not just buy a small 12v supply and forget the DCC bus altogether?

Or that. Probably the most sensible approach. 

[LMS_LNER_SR_GWR_fan2004]

1 hour ago, melmerby said:

Why not just buy a small 12v supply and forget the DCC bus altogether?

 

That's the way I was thinking of going, just to make life easier for me. A quick search found this: http://www.gaugemaster.com/item_details.asp?code=GMC-WM4&r=1

[melmerby]

3 minutes ago, LMS_LNER_SR_GWR_fan2004 said:

 

That's the way I was thinking of going, just to make life easier for me. A quick search found this: http://www.gaugemaster.com/item_details.asp?code=GMC-WM4&r=1

Might be cheaper here:

https://www.amazon.co.uk/s?k=12v+dc+wall+plug&ref=nb_sb_noss_1

[Phil S]

The OP may not want to have either another 230Vac connection and power supply involved - especially if transporting to shows etc.

But an overriding consideration should be how essential is it for the 12Vdc to remain available when the track dcc is removed by either a short circuit or during programming etc ???   If that is not a concern, and the additional load in the dcc bus is low, then a small conversion module for local-conversion on the specific board of the destination product is to be recommended -  similar ready-built modules are available for 5V /USB outputs which can power other useful little gadgets and animations.

My preference is for the animations and other devices to continue independently of the dcc track/accessory signal wherever possible - so that they continue to operate and entertain whilst any problem on the dcc is resolved.  I DO therefore have a 12Vdc bus for laout lighting and effects (6A !) from which I use modules to give me a local 5V where needed.

[melmerby]

3 hours ago, Phil S said:

My preference is for the animations and other devices to continue independently of the dcc track/accessory signal wherever possible - so that they continue to operate and entertain whilst any problem on the dcc is resolved.  I DO therefore have a 12Vdc bus for laout lighting and effects (6A !) from which I use modules to give me a local 5V where needed.

I have a DCC track bus, a DCC accessory bus & a 15v 6A AC bus (some accessory modules use 15v AC)

[Junctionmad]

It should be pointed out, if you derive a power source from the DCC rails and rectify it , you get a “ local gnd “ that is not generally compatible with other Gnds on the layout. 

 

Ie , deriving a supply from the dcc track to power a few platform lights is entirely practical and you don’t really mind the lights going off on a track short circuit 

 

but where you might be interconnecting grounds ( or OV) you need to be careful you know what you are doing 

 

Dave 

Edited June 9, 2019 by Junctionmad