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Author Topic: Need a small power supply for walwart elimination - best way to go?  (Read 415 times)

NEVBEN

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I consolidated a bunch of nominally 12v electronic power supplies by replacing eight "wall warts" with one brick.  The typical draw on the circuit is in the 2A range (as measured with a multimeter), but a full load can draw as much as 4A.  I'm using a 6A-rated brick at the moment.

Even though I'm not drawing more than ~2.5A, my E is drooping to 11.4V.  Without any load, the brick puts out 12.4V.  Sagging 1V might be fine for most of the devices, but I also have a 12000maH LiION battery pack on the circuit (functioning as a UPS).  I don't think I can fully charge the battery at 11.4V.

I think I need either a 13.8V power supply or an adjustable power supply.  I have a sweet Astron RS20A-BB, but it's on the other side of the house powering my 2M base station.

I'm considering an Astron RS12A or Tripp Lite or an adjustable lab power supply like this TackLife.







Maybe any of these are overkill or there is a better option.  Advice?
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W6MK

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #1 on: February 09, 2021, 03:18:49 PM »

Sounds like you want a regulated supply with variable voltage output.

Both Astron and Alinco make such, are good quality and generally well-regarded by most hams.
I'd stick with them rather than other brands. You can check eham reviews.

I'd also consider getting a larger capacity supply, say 25A continuous duty, in case of future needs.
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NEVBEN

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #2 on: February 09, 2021, 03:37:35 PM »

Note this isn't for an amateur radio, but other "shack" equipment.  Got the Astron for my radio, but this is for stuff like two wifi routers, gigabit switch, cable modem, two raspberry pi's, a small PC speaker, etc.  Not looking for 25A continuous because like I said, it's eight devices and rarely draws over 3A.

Come to think of it, I could use a power supply to replace four wall-warts for my Kenwood HT chargers.  Those are rated 0.85A each.  The thing is, they're in a different place in the house by the front door for grab-n-go.

For stuff like this, I need something between a wall wart and a 35A linear.  It doesn't make sense to sprinkle big linears all over the house everywhere I've got gadgets.  On the other hand, the wall warts can get out of control like tribbles.
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SOFAR

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #3 on: February 09, 2021, 03:43:17 PM »

What model of Kenwood HT?
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KL7CW

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #4 on: February 09, 2021, 04:34:02 PM »

Pro Audio Engineering makes a nifty 4 amp 14.4 V RF Quiet power supply which is just slightly larger than a pack of cigarets.  They advertise in QST and many of us use them for our KX2 and KX3's.  Just order directly from proaudioeng.com or other sources. Do be careful in using a regular power supply to charge any battery.  Most battery chemistries require specific charge rates, limit charge time, and/or sense the cell temperatures to prevent catastrophic failures (like fire).  I doubt that many of your wall warts carefully control the output voltage, so in many cases if you are in the ballpark all should be OK.  You can go to a thrift store and rummage through their box of wall warts.  If you find a heavy one, it just might be a linear transformer unit which may be RF quiet but may or may not be well regulated.  Good luck,    Rick  KL7CW
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NEVBEN

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #5 on: February 09, 2021, 04:47:37 PM »

What model of Kenwood HT?

I use THK20A's.
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KF5LJW

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #6 on: February 09, 2021, 05:25:52 PM »

Might I suggest you give up on Astrons and other such low quality amateur radio equipment. For about the same or less money you get top of the line commercial power supplies pros use actually made for radios. Look At Samlex models. They can do something no Astrons can never ever do. Operate at rated capacity 100% duty cycle. Example the Samlex SEC 1212 is a 12-amp supply and can supply 12 amps 24 x 7 365. Exactly what one wants if the want to charge batteries. Do that with an Astron and you have a paper weight. You can even get them with an enclosure to contain the PS and radio.

So you can spend $100 for a POS 12-amp Astron that cannot deliver 12-amps for more than a few minutes, or spend $90 for a Samlex SEC-1212 unit that can deliver a full 12 amps all day long and never get hot.

Another top of the line units are IOTA and many smart hams who use batteries use the DLS15. It is both a 15-amp DC power Supply, but can also Float a battery with a built-in 3-stage charger. Put a set of golf cart batteries on one of these wil run anything you can throw at it even if it needs 100 -amps.

You don't have to over pay for cheap amateur equipment. For the same or less money buy quality. Let sammy hammy use the cheap stuff and throw away money. Both have something else Astron will never have, UL listing and certification. .






« Last Edit: February 09, 2021, 05:29:28 PM by KF5LJW »
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NEVBEN

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #7 on: February 09, 2021, 06:21:57 PM »

I'll keep the Samlex in mind.  I've preferred linear power supplies for my radios in the past to avoid high-frequency switching RFI and also the radio interfering with the power supply.  Samlex acknowledges both:  https://samlexamerica.com/support/faqs/faq18.aspx  I know there are workarounds but like I said, I've preferred to keep things simple with a linear and/or a DC battery (Astron BB series) and no high frequency switching. 

What I'm looking for now is not for an amateur radio, but other shack equipment that is normally wall-wart powered.  Of course, from an RFI perspective it doesn't matter what's being powered.  That's why I would consider a linear like the small Astron.  On the other hand, just consolidating wall-warts (and eliminating the noisiest ones), allows me to apply mitigation measures to one or two SMPS instead of more than a dozen.

I'd still like to get a good result without spending ~$100, especially considering that I could use these in two or three locations around the house.  That pretty much rules out linears.  Even used on eBay, they tend to run ~$80 with shipping.  Maybe I'm looking for a unicorn -- cheap, high-quality 12V power.  Have you counted how many wall-warts, SMPS, and buck converters are in your house?  I attacked a concentration of 8 of them in one place.  I'm just trying to use good engineering practices without over-engineering.
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W9FIB

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #8 on: February 10, 2021, 10:03:05 AM »

Look on E-Bay for old CB radio power supplies. See many in the 3-5 A range under $20. Simple and easy to fix if needed.
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73, Stan
Travelling the world one signal at a time.

WB4SPT

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #9 on: February 15, 2021, 09:12:09 AM »

I’ve got a Lambda LQ-521 for sale.  Recapped, tested/fixed for RFI.  0-20V 3.3A cont. adj V and current limit.
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VE7REN

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #10 on: February 15, 2021, 10:34:08 AM »

i second the samlex brand power suplly. the 1212,1223,1235 are rock solid. ive used them for years here,with never a issue.
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NEVBEN

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Re: Need a small power supply for walwart elimination - best way to go?
« Reply #11 on: February 15, 2021, 06:51:52 PM »

I decided to buy a few "smart" or "intelligent" battery chargers and try them in lieu of a wall-wart or brick.  Here's what I found:

First, bear in mind that my equipment is drawing as much as 4A peak, so many of the typical one or two amp "trickle" chargers won't work.

Second, most of the smart battery chargers need to sense some voltage, usually at least 2V before they will charge, so having a battery or maybe a capacitor on the circuit is essential to make them work.

Third, the LiION battery I have already has a complete "intelligence" circuit with protection and charging devices built-in.  It is designed to be charged by a wall-wart and does not need a proper battery charger.

Chiefly, I tried a NOCO Genius 5.  This is a 5A "smart" charger.  I also tried a couple of knock-off brands that were half the price.  One looks to be a Russian design made in China, and the other is all-China.  Both these latter chargers have rather loud fans.

The Russian job is labeled "Foxsur."  It's too loud to power my pile of Wifi and Pi stuff, but it has a feature to "pulse" the charge (voltage) to desulphate and destratify batteries.  I used it on an 12-year old AGM battery I have in my pickup truck and it brought it from a OCV of 11.8V to and OCV of 12.4V, tested at least 24 hours since it was on the charger.  My regular NAPA battery charging cart could not do that.

The NOCO similarly has a "repair" function to desulphate/destratify.  I used it on a 6-year old AGM battery that had an OCV of 12.1V and brought it up to 12.2V -- it did not seem to make much difference, maybe because the battery was not that bad to begin with.

I use the ~$300 Odyssey AGM batteries in my vehicles because they give better performance and last two or three times longer than the flooded lead acid batteries.  They cost a similar factor more, but since vehicle battery failures are potentially grievous, I don't just go by $/year.  For my amateur station equipment, I am likely to use a spare automotive AGM battery because I don't get much value out of a battery just for radio use.  If I were specifying a battery for a station, I would go for the LiFePO like the Battle Born batteries -- better than the old Trojans, but $$ for sure.

For my low-current, Wifi and Pi station equipment, I'm using LiION and once I got it fully charged with the NOCO charger, I tested it and it ran for more than 3 hours on it's own -- powering two wifi routers, cable modem, two Raspberry Pi's, and some other low-current junk.  That's more than I hoped for.  I really only wanted the batteries to provide UPS service during a brief blackout or until an alternate power source could come online and I believe they also smooth out the ripple from the 60Hz-driven power supply -- wish I had a scope to verify that.  The batteries I'm using are TalentCell, which I can recommend.  I actually purchased them to run the LED's on a holiday light parade float (they've worked great for a few years now), but I thought I'd put them to use the other 51 weeks of the year, so they help power the Internet for the home QTH.  I would also check out the TackLife 1200A jump-starter and (12800MaH) power source, or another power-brick that will do quick charging if your phone does that -- I use the 5V USB out to power the Pi's, but the TalentCell won't do the higher voltage USB for Quick Charge 3.0.  Another good bet for station auxillary equipment would be a 12MaH LiFePO battery -- you'd just need a little buck converter if you have any 5V stuff.

The NOCO Genius 5 seems to be a quality product, but it is a bit costly for what it does.  If it had more utility for automotive batteries, it might have greater value, but I found that it did not do anything my NAPA charging cart does not do, and the NAPA cart will charge 40A continuous -- it's got a softball-ball sized transformer in it.

The Foxsur's pulse feature might turn out to be valuable.  It will take another week or so of treating a few old batteries I have and letting them rest to see if they hold the OCV.

« Last Edit: February 15, 2021, 07:02:10 PM by NEVBEN »
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