Best 12v power supply for powering Digitrax components?

[Ed Kapuscinski]

Ok, so it seems like the play is to get a laptop power adapter, the Tam Valley pin out and then make my own power distribution board for all of the devices.

Sound about right?

[John]

Quite timely ..

[mmagliaro]

One word of advice.  Hunt around and find a laptop adapter close to the voltage you actually want, rather than find whatevery you can get cheap and then pile on diodes to drop the voltage (like this fellow shows in the video).   Using diodes that way works, and heck, I've even used that trick for something like a fixed lighting power supply.   Years ago, I built something like that for Spookshow to run lighting on one of his layouts.  But this is 2024, and using diodes here isn't a good application of the idea. 

Let's say the capacity is 5 amps for a typical booster.  Dropping 19v to 16v will require 3/ 0.7 = or 4 to 5 diodes, each dissipating .7 x 5 = 3.5 watts at full load.  Altogether, they will be venting 16-20 watts.  Yikes, that's a monster amount of heat.  You will need a huge aluminum plate (like maybe a square foot) to mount those diodes on.   Another issue is that large diodes like that do not drop "0.7 volts" all the time.  We conveniently toss that number around because it is the nominal drop for a diode, but from low to high current, that diode drop might actually vary between 0.6 and 0.9v .  So 5 of them will swing the output by 1.5 volts.  For something like accessory power or lights, nobody would probably care.  But having your DCC track voltage vary between 14 and 15.5 volts depending on how much load you have on it might cause some once-in-a-while weird behavior.   You could reduce this somewhat by hunting down power Schottky diodes, but who needs all the hassle?  Find a 16 volt laptop adapter and be done with it.

[Point353]

Find a 16 volt laptop adapter and be done with it.

https://www.digikey.com/en/products/detail/cui-inc/SDI120B-16-U-P51/22042535
https://www.cui.com/product/resource/sdi120b-u.pdf

[mu26aeh]

Related to Digitrax power supplies and such, I posed this question to Ed and he said to add it to this thread so I will.

The PS514 has these different size barrel connectors with 2 pins on them, but specifically mentions using the blue one.  Well I broke one of the pins off the blue one, so I only have the 7 other ones that have the same 2 pins but different size barrels that don't help me.



So 2 questions here, 1) where can I get a new blue barrel connector, as I didn't see them available on Digitrax website.  And 2) what do the other connectors do, why do they include them with no apparent description for use ?

[peteski]

That adapter to me doesn't look like an off-the-shelf item. It looks more like some custom piece made specifically for that power supply.  Can't you contact the manufacturer of the supply to see if they can sell you a replacement?

Or just figure out the size of the barrel plug, buy a plug then just cut off the the other part that is on the end of the cable and install the new plug onto the end of the wire.

[mu26aeh]

This is what comes with the Digitrax PS514.  An entire strip of connectors with different size barrels, though only the blue one fits and is mentioned in the instructions.



I figured it wasn't an off the shelf item but figured someone else has gone thru the issue of having to replace it.  I haven't contacted Digitrax about it yet.

[dem34]

Related to Digitrax power supplies and such, I posed this question to Ed and he said to add it to this thread so I will.

The PS514 has these different size barrel connectors with 2 pins on them, but specifically mentions using the blue one.  Well I broke one of the pins off the blue one, so I only have the 7 other ones that have the same 2 pins but different size barrels that don't help me.

So 2 questions here, 1) where can I get a new blue barrel connector, as I didn't see them available on Digitrax website.  And 2) what do the other connectors do, why do they include them with no apparent description for use ?

Anywhere that sells assorted electronic components will usually have these strips. They exist because its a crapshoot what type of barrel jack an mfg will put on a device to receive low volt DC. And similarly you may have a supply that matches what you need but it doesn't have the right barrel. These strips are super cheap and can be bought in bulk so no harm in throwing them in just in case an end user has a dedicated power supply but its output barrel doesn't match the digitrax unit. Why the full variety? They come like that in bulk from the supplier and they probably mathed out that its cheaper to throw the whole thing than pay someone to separate them out.

[TravelingCarpenter]

Powerwerx is what I use for my DIAB ( district in a box) booster for free moN
https://powerwerx.com/variable-power-supply-digital-meters-30amp

TC

[Ed Kapuscinski]

Ok, it's time to get to work on this for real and of course @mmyers 's power supply link died.

Can I just use a Digitrax PS615 90W AC/DC 15VDC 6 Amp Power Supply broken out to power the various components?

[mmagliaro]

Ed, I don't see any problem using that Digitrax box (the  Digitrax PS615 90W AC/DC 15VDC 6 Amp)
And yep, you can break out the output cable, strip the wires, test with a multimeter so you know what's what,
and that should be fine.
But sheesh... $79??  (okay, discount retailers have it for about $62)   That seems really steep for what is essentially just a laptop power brick.
You can get 90W 15V adapters off Amazon or ebay for under $20.   In fact, some of them even tout themselves
as "PS615" equivalents.  Sure, they are knock-offs from China, and yes, if Digitrax guarantees everything they sell, they will replace it if it smokes.  But be aware that their PS615 is also just a rebranded one from China.

JameCo has equivalent ones for about $30 if you want more of a retailer guarantee (Make sure to get the ones
that INCLUDE the power cord.  Some don't and they are priced cheaper).

They are all switching, overload protected adapters.

 $62 is a lot of scratch for an adapter like that.

[Ed Kapuscinski]

So like this bad boy right here:
https://www.amazon.com/Kircuit-Adapter-Compatible-Digitrax-LocoNet/dp/B0CTTQFJKG/ref=sr_1_4?crid=2JCP2JE84RNPK&dib=eyJ2IjoiMSJ9.AlrwbViQCXIgpPLGADHcKJ0h_mxeWjwrKNomugdh0Mu11gr_ycOaKQIYOzU0jUbyNoTTuvklpOhyx1vr9IOsQILaPbZnLn_c1T9pcIqDZDzDHUShFHYiPCu26Sejg0il8USGenRafoQVVk-N9EiPtR76oBsbzLXP_e8ZKcNmoVJt9ASXI99p_Y0eixEVkOjpRTFyUuwfLsHVZQwhSZyqj2GpJjDmJyWp_MfC_s8ywWNAQ1cLgMojugz6rQ717Qraf__PTYBBEPM0RTXKWr6Lurq52BIKsbt4ZhvEIhrwBek.GhlYeZRK3GGxioh745YwUX8Xg6Kbvot9X3FM7sRBTXs&dib_tag=se&keywords=ps615+90w+ac%2Fdc+15vdc+6+amp+power+supply

And it sounds like, from there, use a 2.5mm female plug, split into a handful of 2.1mm male plugs, and then away I go.

Here we go!

[Scottl]

Guitar pedal effect power supplies come with daisy chained 2.1 mm plugs.  Some even come with 12V supply as well, but most are 9V.  The former might save some fabrication.

[mmagliaro]

Ed, yes, that one looks like it would do the job.   I think I would pick one that at least has some reviews on it if you are going to get one off Amazon. That particular one says, "Power fuse for rapid charging and over charge protection"
It's probably just an issue of language translation, but I don't like them saying it has a "fuse".  Other ones very similar to that one usually say something like electronic overcurrent protection, or something like that. 

I like these better:

https://www.amazon.com/COOLM-100-240V-Supply-Adapter-Converter/dp/B07CBTWT1V/ref=sr_1_1?dib=eyJ2IjoiMSJ9.AlrwbViQCXIgpPLGADHcKJ0h_mxeWjwrKNomugdh0Mu11gr_ycOaKQIYOzU0jUbybtzwvMyFK7Oq46-jm-GI4acNr6QhGncWI4Xh8B3UiRsKSI2N3i1hobaV2KI9TfavEDYgUxxp3_Rt-4ODp9tLXh76oBsbzLXP_e8ZKcNmoVJCuPAxv_zb1Rcr-LZpXFfTKI75eY9ClSOGGg2qvxQ77k1ZQTZPTovhLBXN2O-249wozM3R7y6ke6e4CQttSfoaTJp-8rkphDCYaiFyFrzC89g3PBNeyEvPE-DJ2W8MUtg.DM0y0U6598CWtayik9jnq84yiBAeYk25DqnyWbGDTfU&dib_tag=se&keywords=ps615+90w+ac%2Fdc+15vdc+6+amp+power+supply&qid=1721882192&s=electronics&sr=1-1

https://www.amazon.com/Digitrax-DCS100-DB150-DB210-Power/product-reviews/B08KRQVPGF/ref=cm_cr_dp_d_show_all_btm?ie=UTF8&reviewerType=all_reviews

They mention "short circuit protection, overload protection, over voltage protection"

And at least they have a few reviews.