Power Supply for DCC System

QUOTE (zmil @ 2 Jul 2008, 21:35) <{POST_SNAPBACK}>Hi All
What , if anything , is special about the power supply (Transformer) for a DCC system ?

One of my Roco 50VA power supply decided to stop working (no volts from the output)
I haven't tried to open it up just yet

I just wondered if I could use a generic AC 16v transformer or is there something else needed in the circuit ?
I only use this set up on the work bench and I have a few spare transformers rated at 1.2 amp uncontrolled AC

Regards Zmil

*** All transformers aren't equal, although there is nothing "DCC specific" about them other than a need for quality and consistency in voltage and power delivery under load.... To be honest most provided by the Mfr are built to a price and aren't very good at all.

I actually specially modify & sell a very high quality power supply for DCC use - The core issue is good stable voltage whether AC or DC.

In that, your trainset transformers will not be at all good - they may be 15v rated, but they'll be about 18~19 volts with no load and about 11~12 when close to the limit - and a 1.2 amp transformer will NOT be powerful enough. (15v and 1.2 amps is only 18VA).

I provide my own brand supply with both regulated [email protected] 14.75 volts and 16V AC @ 5 amps, but strongly recommend the regulated DC as the best output to use for DCCC controller use... it generally gives a near ideal 13.5 volts at the rails.

If you don't want to invest in a quality supply, then a Laptop computer power supply is the next best choice - much better voltage stability and this results in a more consistent DCC layout peformance. they are usually 15~18volts at 3.5~5 amps depending on the brand - and while 15v is better, up to a max of 18V DC will do the job reliably.

regards

Richard
DCCconcepts

Hi Richard
I knew you would have a intelligent answer.

I don't need one straight away. I still have 1 good transformer
a bit of a mystery why the other one died . It worked one day didn't the next.
It may have an internal fuse. The Roco transformers are also marked as 230v
Western Power like to give its customers a variety I've measured as high as 265v

What sort of $$ are the 5 amp Power supplies?

Regards Zmil

QUOTE (zmil @ 2 Jul 2008, 22:07) <{POST_SNAPBACK}>Hi Richard
I knew you would have a intelligent answer.

I don't need one straight away. I still have 1 good transformer
a bit of a mystery why the other one died . It worked one day didn't the next.
It may have an internal fuse. The Roco transformers are also marked as 230v
Western Power like to give its customers a variety I've measured as high as 265v

What sort of $$ are the 5 amp Power supplies?

Regards Zmil

***Hi

Yes, and that is a REAL problem with the Roco system.

Its already about 18 volts if the power supply is being fed voltage to match its spec, but if a 230 volt transformer is fed with say 250 volts then the output becomes about 20 volts, which is totaly excessive and will cause some of the real problems that I've seen with decoder life, loco light bulbs, smoke units and system life with Roco and other products bought with EU made AC transformers.

My power supply is $110 - and will give the same correct voltage out no matter what variation in local power! Its a substantial beast - nearly 2 KG!

Richard
DCCconcepts

Richard

QUOTE (Richard Johnson @ 2 Jul 2008, 22:13) <{POST_SNAPBACK}>***Hi

Yes, and that is a REAL problem with the Roco system.

Its already about 18 volts if the power supply is being fed voltage to match its spec, but if a 230 volt transformer is fed with say 250 volts then the output becomes about 20 volts, which is totaly excessive and will cause some of the real problems that I've seen with decoder life, loco light bulbs, smoke units and system life with Roco and other products bought with EU made AC transformers.

My power supply is $110 - and will give the same correct voltage out no matter what variation in local power! Its a substantial beast - nearly 2 KG!

Richard
DCCconcepts

Richard

Yes I think I will invest in that first before I do anything else!

Starting with a good power supply will save money in the long run
If you consider the expense of every thing connected to it!

Id better list a few more things on FeeBay

This weeks bills are killing me

Thanks again for the good advice

Regards Zmil

QUOTE (Richard Johnson @ 2 Jul 2008, 14:13) <{POST_SNAPBACK}>***Hi

Yes, and that is a REAL problem with the Roco system.

Its already about 18 volts if the power supply is being fed voltage to match its spec, but if a 230 volt transformer is fed with say 250 volts then the output becomes about 20 volts, which is totaly excessive and will cause some of the real problems that I've seen with decoder life, loco light bulbs, smoke units and system life with Roco and other products bought with EU made AC transformers.
This is a bit OT but may be interesting: Historically, the UK has used a slightly higher voltage (240V) than other European countries (230). Now, the supply voltages have been harmonized across Europe so that we all use the "same" voltage. In fact, nothing has changed, all that happened was that the tolerances were adjusted so that the UKs 240V +/- something is within the new EU voltage range of 230V +10%/-6%. There's been a problem with "230V" incandescent bulbs having short life in the UK.

Andrew

QUOTE (SPROGman @ 2 Jul 2008, 23:24) <{POST_SNAPBACK}>This is a bit OT but may be interesting: Historically, the UK has used a slightly higher voltage (240V) than other European countries (230). Now, the supply voltages have been harmonized across Europe so that we all use the "same" voltage. In fact, nothing has changed, all that happened was that the tolerances were adjusted so that the UKs 240V +/- something is within the new EU voltage range of 230V +10%/-6%. There's been a problem with "230V" incandescent bulbs having short life in the UK.

Andrew

Hi Andrew
Strange you should say that
The same happened in WA the rest of Australia was on 240v WA had 250v They changed to a Nation wide standard 240V about 25 years ago
I was working for a electrical supply Co at the time we were still selling Incandescent Lamps to the Mining Companies rated at 260v for longer life and they were getting harder to source.
Measuring Mains voltage in a small mining town can give you very large variations
One of the lamp suppliers told me a 5% lower voltage can double the life of a Incandescent lamp

However we had some nasty experiences the other way - low voltage in one place ,
doing sound system hires ,we had a few digital units that at 210v would stop working and switch off
DSP128 multi-effects was one that comes to mind plus system protection devices built in to active crossovers
sound one minute none the next!
There's always another story horror or other wise

Regards Zmil

QUOTE (harkins77 @ 3 Jul 2008, 10:52) <{POST_SNAPBACK}>So Richard if you are saying a laptop power supply will work, would it also boost my amps rating on my nce powercab like the boosters or is that a whole kettle of fish I am talking about?

Sorry if that is a really silly question and no I haven't done it.

***HI

Nope, the powercabs rating is slightly conservatively stated and is actually just over 2 amps but the limit is the onboard electronics and not the power supply. Sorry but the only ways to increase it are via a PHP system box or a smart booster. To be honest with a medium sized N scale layout you will never reach the limits of the PowerCab anyway, so don't worry too much.

Regards

Richard
DCCconcepts

QUOTE (Richard Johnson @ 2 Jul 2008, 21:50) <{POST_SNAPBACK}>If you don't want to invest in a quality supply, then a Laptop computer power supply is the next best choice - much better voltage stability and this results in a more consistent DCC layout peformance. they are usually 15~18volts at 3.5~5 amps depending on the brand - and while 15v is better, up to a max of 18V DC will do the job reliably.

regards

Richard
DCCconcepts

Hi Richard
I may buy a laptop supply off FeeBay so I can sell one of my control systems to fund a new DCC Power Supply
Most of them seem to be around 4 Amp and voltage from 14.5 to 18.5VDC depending what brand off laptop they are for
I have 2 Roco MultiMAUS and an old Lenz system
What should I look for and will these systems accept DC input as a Power supply
Both systems must have some power regulation built in (Lenz can be changed internally)
will they mind a DC power supply?
Regards Zmil

QUOTE (zmil @ 5 Jul 2008, 12:08) <{POST_SNAPBACK}>Hi Richard
I may buy a laptop supply off FeeBay so I can sell one of my control systems to fund a new DCC Power Supply
Most of them seem to be around 4 Amp and voltage from 14.5 to 18.5VDC depending what brand off laptop they are for
I have 2 Roco MultiMAUS and an old Lenz system
What should I look for and will these systems accept DC input as a Power supply
Both systems must have some power regulation built in (Lenz can be changed internally)
will they mind a DC power supply?
Regards Zmil

***Target is 15V DC. Up to 18 is OK

No, they'll be the better for DC for all the reasons listed earlier. Actually they do have some limited regulation but its effectiveness is often restricted by the ability/stability of the power supply used.

The first component inside their black box is always a rectifier anyway - DCC/digital systems are actually as a result DC powered for all active circuitry and generate their own internal waveforms as needed with no reference to mains AC at all.

Richard
DCCconcepts