Quiet DCC Power Supply

[jereising]

I've got a Digitrax 2012 and the fan is driving me nuts.

Any suggestions for something around 30 amps DC variable without a cooling fan?

120 VAC in of course.

I run a command station and three boosters...

TIA!

[C855B]

No fan? Unlikely. Even switching power supplies are dealing with a lot of heat. No fan = POOF! You might find a PS with a quieter fan, but OTOH my direct experience is that quieter means less air movement, and therefore less heat disposal and the resulting higher stress and earlier failure.

A conventional communications power supply @13.8VDC will work for N, as the "variable" part is simply for higher voltages supporting larger scales. My preferred brand for higher-current supplies is Astron, but I cannot speak to the fan noise as I typically installed them in large-building equipment rooms, where fan noise would be an indiscernible contribution to the rumble and clatter.

[jereising]

Thanks, Mike.

I was afraid of that.

I COULD mount the PS on the other side of the wall at that location, which would quiet things a lot...

Funny how sometimes the little things bug you.

[C855B]

Oooo! You're in luck! I stand corrected! I wasn't thinking about the Astron linear power supplies, which are what we call "brute force" (transformer + rectifiers + capacitors + regulators), rather than "switching".

Look at this: http://www.hamradio.com/detail.cfm?pid=H0-004434

25A continuous, 35A peak, no fans. The regulators live on a monster heat sink on the back. Price not bad compared to street price for the Digitrax 2010.

[GaryHinshaw]

Mike's solution looks good.  Another option is to use one of these per booster/command station.  They are dead quiet, but 4 of them will set you back a bit more than the 25 A supply.

[peteski]

Surprising that a linear power supply has no fans while a switching supply does.Where linear supplies have to dissipate all the extra internal power as heat, switching power supplies are much more efficient (so they should theoretically run much cooler).

[jereising]

The info is greatly appreciated - gives me a lot to think about. 

[C855B]

Surprising that a linear power supply has no fans while a switching supply does. ...

The primary component that makes a linear supply run hot (and waste power) is the regulator. Hang that on a big enough heat sink and you're done.

It's been 15 years since I installed my last transmitter, so in all honesty I was surprised to see all the boat-anchors still in the Astron catalog. I guess linear supplies remain popular in communications because of their low noise ("noise" in the electrical sense, not fan noise). Switching supplies for years were "dirty" especially under high loading, and you'd hear the crap in the signal or it would even interfere with receivers, generating RF noise.

[fcwilt]

I've got a Digitrax 2012 and the fan is driving me nuts.

Any suggestions for something around 30 amps DC variable without a cooling fan?

120 VAC in of course.

I run a command station and three boosters...

TIA!

A few questions, please.

Are all of the command station/boosters 8 amp units?

What voltage are you looking for?

What is your budget?

There are reasonably compact, fan-less, switching supplies but they may be too pricey.

Frederick

[jereising]

A few questions, please.

Are all of the command station/boosters 8 amp units?

What voltage are you looking for?

What is your budget?

There are reasonably compact, fan-less, switching supplies but they may be too pricey.

Frederick

Frederick, the Astron unit Mike shared seems to fit the bill nicely, and can be had with metering as well.

But I'm gonna try putting it on the other side of a wall (which puts it into a storage area) to kill the sound.  That's by far the least expensive way to go. 
What that doesn't do is give me any headroom - my command station and boosters are all 5 amp. 
Having said that, I doubt I've ever approached the limits of the PS 2012, sooo...

[fcwilt]

But I'm gonna try putting it on the other side of a wall (which puts it into a storage area) to kill the sound.  That's by far the least expensive way to go. 

What that doesn't do is give me any headroom - my command station and boosters are all 5 amp. 

If you are going to put it on the other side of the wall why not use the existing power supply?

And with one command station and three boosters, all 5 amp units, you really only need a 20 amp supply - assuming you can pull that 20 amps constantly under your environmental conditions.

"Headroom" doesn't really apply in this type of situation.

Frederick

[jereising]

I made the move today and boy, what a difference.  It's gone from heavy breathing to a whisper. 

In the process I found a couple of things that might have contributed to problems - Digitrax puts a cap in the hot lead of their wye connectors.  They use crimp connectors.  Several were loose, one actually fell off.

They needed extending anyway, so now everything is nicely soldered.  Bit of a pain to have to do the extra work, but I'm used to that.

I know I don't need "headroom"; but I'm conservative and prefer to only use 3/4 of what's available.

Thanks all!

[fcwilt]

... - Digitrax puts a cap in the hot lead of their wye connectors. ...

Thanks all!

Hi,

If memory serves those are PTC fuses - they do look like caps.

Frederick

[reinhardtjh]

Hi,

If memory serves those are PTC fuses - they do look like caps.

Frederick

You are correct.  I hope Jim didn't remove them.

[jereising]

Nope, figured they were there for a reason.  WHAT the reason was for a cap in the hot lead I didn't know, but I figured it needed to be there.  Never had PTC fuses in the dark days.  If it looked like a cap it was a cap.

My formal electronics education was in the day of the tube, transistors and ICs were just beginning.   Now I'm feeling old!

Good thing I didn't just do away with the wye connectors and straight wire the PS to the boosters - which I thought about for a bit.

Ya learn somethin' every day.   TRW is an education all it's own.  Explanation appreciated.