Inexpensive +/-50V dual output bench supply

[alex912]

Hi all,

I'm looking for advice on a bench power supply for a specific project, but also as a general-purpose tool (hence why I'm posting in this forum instead of the project forum). I'd like to have the adjustability, built-in meters, and compactness that a bench supply gives -- so I'm avoiding "system"-type power supplies. I'd like to stay (far) under $400 if possible.

My application is an ultrasonic transducer amplifier chip[1] which lists absolute maximums of 100V input (-Vs to +Vs) and 30A output. The datasheet also lists a maximum internal dissipation of 250 watts. This is a bit confusing to me, but my interpretation of this is that if I run at +/-45V, I should require my supply to handle at most 2.8A. (Is my interpretation correct?)

In order to get the negative and positive voltages I need, I've been looking for both dual/triple output supplies, as well as just getting 2 isolated supplies. My extensive searches of eBay have only brought up a few options.

One option is a Lambda LQD-422[2], which can do +/-40V at 1A (if I'm reading the datasheet correctly). There's also a higher voltage version LQD-424 available, which claims +/-120V at 0.38A. I'm confused by the part where it mentions that rated current outputs are constant across the voltage range. Is this normal? I would have expected the power output to be constant, meaning the supply would be able to handle higher current at lower voltages.

The $640 B&K Precision 1762 is the cheapest reputable supply I can find, but it's just a bit too expensive for this project.

Another option that's popped up a few times is the RXN-603D-ii ($310 +/-60V@3A) and RXN-605D-ii ($370 +/-60V@5A). But I can't find any reviews of these, and I'm reluctant to spend so much money on something that might turn out to be poorly built or even dangerous.

I've also considered using the cheap regulated supplies that Dave reviewed recently[3]. But I would still need a relatively high voltage DC input power supply to feed the regulator. I did see a buck-boost version that might work (DPH5005, max 50V @ 5A), but again I'm unsure about what input supply I'd use to feed it.

I would very much appreciate any advice anyone can give!

Thanks
Alex

[1] https://www.apexanalog.com/resources/products/pa05u.pdf
[2] https://testequipment.center/Product_Documents/TDK-Lambda-LQD-422-Specifications-E397A.pdf
[3] https://www.eevblog.com/forum/blog/eevblog-1030-$20-diy-bench-power-supply!/?all

[nctnico]

I've seen the RXN-605D for $100 (ex. shipping) on Ebay. Depending on how much time you have it might be an option to buy these and improve their safety if necessary (I don't know). Adding some 10 turn pots will be a good option as well.

[alex912]

Do you think that getting 2 RXN-605D and putting them in series would be better than a single RXN-605D-ii?

Oddly enough, it looks like 2 single output versions are actually cheaper than the dual output version.

[DC1MC]

're in USYou have to think out of the box  , and remember you're in US, the land of opportunities.

I present you AGILENT 6627A, not two but FOUR fully isolated power supplies, to put them in whatever configuration you need:

https://www.ebay.com/itm/Agilent-HP-6627A-Quad-Output-DC-Power-Supply-0-50V-0-0-8A-0-20V-0-2A/372211327632

Best part: a bit over HALF of your buget  .

 Cheers,
 DC1MC

[alex912]

I did find that option, but it's limited to 50V@0.8A and its in a clunky form factor (3U system power supply; terminals in the back; no knobs for quick adjustments; etc).

Although since it's 4 outputs, does that mean I could run a series of two pairs of paralleled outputs, in order to get -50V to +50V at 1.6A? (Assuming the outputs are all isolated)

It certainly might be worth another look -- thanks!

[DC1MC]

Quoting from the datasheet https://literature.cdn.keysight.com/litweb/pdf/5990-9302EN.pdf?id=2159019:

Up to four fully isolated power supplies in a 3U package

So you have 4 in 1, fully isolated power supplies, to connect them as you seem fit.

Some variants of them are connectible in parallel, see page 3 of the data sheet and chose your best fit.
Also the operating manual has better descriptions:
http://literature.cdn.keysight.com/litweb/pdf/5957-6377.pdf

For the application to the transducer, the Chinese stuff like RXN-603D-ii and friends may be OK, but nothing brand name with this specifications are going to be in your price range.

But still this may be better, and it has buttons and lots of current  :
https://www.ebay.com/itm/Topward-Electric-TPS-4000-Dual-Tracking-DC-Power-Supply-30V-3A/272738294933

Cheers,
DC1MC

[GigaJoe]

i have 2 similar 662X- something ...  output 2x50V-2A or 20V-5A (100W - channel)
in overall I don't use it daily, a major problem even not a size, but really uncomfortable management if you need a dual source, each channel on\off separately, like select ch-1 , disable, select ch-2 , disable .... it suck. same seq to turn it on.   the min Amp triggering 50ma.  sometimes i need lower.  When overcurr.  went off, a small indicator on the screen appears, need to look with attention, then look again on the second channel and so on.... it design to use with automated system, front panel just an option ....

but it 4 quadrant, so you can use it as load , an sometimes overvoltage protection does help , when i debug electronic load, by mistake feed this PSU by another one +30V, it just shut down , no worries 
but hesitating to sell .... 4 channels up to 50V-2A covers my needs at 120%.

dual need  a simultaneous ch. on\off - very handy

a couple broken GPC-3020 appears on ebay, maybe an option.

Oh yes ... an diy option:
https://www.ebay.com/itm/323107922787
https://www.aliexpress.com/item/32596330856.html