DCC power supply

[Tanksley]

I'm ready to buy a dcc power supply for HO layout.  I only run 2 locos.  I want a good power supply that will give my locos speed and run the decoders without loss of power.  What do you suggest?

[MisterBeasley]

Are you looking for a power supply for a DCC system, or are you looking for a DCC system itself?  There is some confusion at times, because many DCC systems do not come with a supply that plugs into the wall.

I have a Lenz DCC system that falls in that category.  I ended up buying an NCE 5-amp supply that works great.

[jrbernier]

  Many DCC 'systems' do not include a power supply.  The higher end Digitrax and NCE systems fall into this area.  I have a Digitrax  5 amp Chief system, and I originally built a 6 amp power supply from a 'kit' from Loys Toys DCC.  I got a deal on a pair of Digitrax 5 amp 'wall wart' power supplies and a DB100a booster..  I gave the Loys Toys power supply to a friend who needed a one.

  Smaller 'starter' systems like the NCE Power Cab and the Digitrax Zephyr include the wall wart power supply.  The Power Cab is rated for a little less Than 2 amps, and the Zephyr is rated at 3 amps.  Both are perfect for home layouts.

  The bottom line is that you can buy a 'wall wart' power supply from Digitrax/NCE/Tony's for about the price of the parts you need to build one.

Jim

[Capt. Brigg]

Can you hook up a 9VDC and a 5VDC transformer (wall worts) to make a 14VDC power supply, being careful to hook the positive of one to the negative of the other and use the two free wires to make 14VDC? I have available a large supply of 9 & 5 vdc transformers used to power computer parts and would like to make use of them instead of the PS14s that Digitrax wants $10+ to buy.

Capt. Brigg
Pacific Cascade Ry in HO

[richg1998]

You can if you know what you are doing. The power supplies need to have the same current rating.  If a 9 volt, 0.5 amp with a 5 volt 3 amp. You will burn up the 9 volt transformer when the current exceeds 0.5 amp. You better understand ohms law. You cannot change it.

Questions like this scare me.

 

Rich

[Capt. Brigg]

Yes, one must be careful, as with all electronics. However, if both transformers have the same current rating and are connected to a unit requiring less than that maximum current rating, it should not be a problem. Some of us are required to make our small RR allowance go as far as possible. Since it has been 40 years since I was an USAF electronics tech, I wanted to be sure I remembered this correctly. I still remember grabbing hold of a small 4,000 volt charged capacitor. Thanks for the confirmation.

Capt. Brigg

[SRN]

Neither of those devices is going to put out very pure DC. Wired in series, you may get a really odd waveshape out of the lashup, especially if they have markedly different internals. If one or both uses half wave rectification and their transformers are not in phase, it could get really interesting. Hopefully, they will both actually contain transformers.

My advice, spend the ten bucks.

 

[MisterBeasley]

Capt. Brigg

Can you hook up a 9VDC and a 5VDC transformer (wall worts) to make a 14VDC power supply

Can you?  Yes.

Should you?  No.  This will, as was pointed out, give you at best a poor DC source.  Most wall-warts are designed for small loads like cell phone chargers or little electronic boxes you didn't need in the first place.  They are typically under an amp, which isn't going to do much for your trains.

Do yourself a favor, and spend a bit for the right equipment.  Don't starve or "malnourish" your DCC system.

[Capt. Brigg]

Since I would only be using the combined transformers in place of a PS14 which is 300 MA, I don't think it should hurt if they are less than 1 amp. One should not use this transformer lash up in place of the power for a 3 amp booster. I already have a Digitrax Zephyr for track power. Thanks for the advice.

 

[tstage]

In order not to highjack the original thread from the OP, perhaps this side conversation could be started in another thread?  Just a thought...

Tom

[SRN]

DC wallwarts are not transformers. They are el cheapo power supplies, almost always of the unregulated variety. That means their output voltage and waveshape are largely dependent on their load.  Unless you have access to some fairly sophisticated test equipment, you will not know what their combined output really looks like. Nor will you be able to accurately measure their output voltage.

Since you will be using these devices outside their design criteria, you have no guaranty they will operate to their stated specifications. That is the nature of unregulated power supplies.

 

 

 

 

[richg1998]

I have put two in series but I know both had a full wave bridge rectifier and one filter capacitor.

If you do not know what you are doing, I would not try it.

Some may be a switching supply which differs quite a lot from a standard wall wart. Switching supplies will generally say 120 VAC to 240 VAC.

A standard will say 120 VAC only for USA types.

Switching wall warts weigh less than a standard wall wart. Another way to tell the difference.

Ripple for a half wave rectifier is 6o Hz.

A full wave rectifier, 120 Hz

A switching supply, don't know but I do know the ripple if any will be much higher frequency. I will drag out the Scope and take a look out of curiosity.

Rich

[farrellaa]

I agree that you should purchase the power supply designed to run the DCC system. I just bought a 3.0 vdc wallwart to power some LED's on a panel. The LED's seemed very bright so I checked the output of the PS with my VOM and it was putting out 5.94 volts! I have checked several wallwarts I had on hand and MOST are off from their rated output.

 - *Bob

[Hamltnblue]

To the OP.  Good starter sets for what you have are the Digitrax Zephyr, and NCE Powercab.