Let's talk about "Decent cheap Bench Power Supplies", OK?

[GregDunn]

Other vintage supplies which could work are HP6236B and HP6237B (my favorite) triple output power supplies.  They don't have current limiting, but the circuitry is in there and external pots can be easily added.

We had several of these on the bench where I worked, and when I found one at a hamfest recently I jumped on it.  Nice, compact, reliable little units.  Plenty of power and adjustability for combination analog/digital breadboards.  The 6236B can be set up with two of the outputs as ±20V or +40V because it has separate common and earth terminals.

[bd139]

They are very nice indeed. I recently repaired a 6237B. The reference Zener was duff. Snagged it for £25 (~$35). Cleaned up like new!

Insides: https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1610257/#msg1610257

[exe]

Heatsinks, transformer and enclosure are the most expensive bits TBH and I reckon for something equivalent you're looking at $300 min.<

It's not cheap, but not that expensive.  250-300VA toroidal trans costs 40-50euro (https://www.tme.eu/gb/details/tts300_d230_17-17v/toroidal-transformers/breve-tufvassons/). Heatsinks 10-20euro each. Enclosure -- I dunno. It can be very expensive (and ugly).

For my ongoing project (90W) I bought an ABS enclose (17euro) , the previous one built in a plastic box from ikea (10euro). Thermal dissipation is a problem with plastic enclosures (I have a low-noise pre-regulator to keep efficiency relatively high). Also don't provide shielding, don't know how much more noise is picked up because of this.

Nonetheless, I agree that buying equipment is almost always the best option. But less fun . I spent more than $4k over four years for parts and equipment to build a $200 PSU.

[bd139]

I spent more than $4k over four years for parts and equipment to build a $200 PSU.

Exactly. I know when to stop. These were £40 each (~$50)

[exe]

BTW, there a few recognized brands from the past. One is "Power Designs": https://www.eevblog.com/forum/testgear/looking-for-goodinexpensive-bench-power-supply/ .

AGILENT E3620A is also not too bad, but can't display voltage and current for both channels simultaneously.

BTW, has anyone heard of lambda lpt-7202-fm ? (https://www.ebay.co.uk/itm/Lambda-TDK-EMI-LPT7202FM-Triple-Output-DC-Power-Supply/382379780696?hash=item59079c6a58:g:b14AAOSw3EpbfZjZ) . Can be bought for ~$120. I'm in love with how it looks, but never seen a review of it.

[bd139]

Lambda power supplies are very good.

All these older linear designs, apart from TTi, suffer from one turd though and that is you have to unplug everything to set the current limit. TTi one, it has AC and output switches. When output switch is off, the C/V meters show the set point. When the output switch is on, it shows the actual voltage/current. If it goes into CC mode, it flashes the DP's on the current display. And one display per channel because they're all separate

[exe]

you have to unplug everything to set the current limit.

You mean "to short the output"? Can be done without unplugging.

Another issue most of PSU only display current value, but not set value (a dial can fix it if precision not needed, there are dials for multi-turn pots, but I never tried them). That's why I like TFT displays: they can show a lot of things all at once.

[bd139]

you have to unplug everything to set the current limit.

You mean "to short the output"? Can be done without unplugging.

Another issue most of PSU only display current value, but not set value (a dial can fix it if precision not needed, there are dials for multi-turn pots, but I never tried them). That's why I like TFT displays: they can show a lot of things all at once.

Yeah you can do it without unplugging stuff but all it takes is one dicky banana plug and it's an unhappy day. Been there, done that on an old Mastech.

If you can find an old Sorensen or Xantrex XT series power supply they are quite similar to the TTI - they will let you adjust the current limit down on the fly. (actually both of my supplies with adjustable current do) The Sorensen toggles LEDs to show you when the current limit is active. If you bide your time, they are sometimes purchasable for about the cost of a new supply but they are built much more solidly.

Sorensen ones are actually TTI ones that are rebranded. TTi stuff is top quality stuff actually made in UK 

[Wolfgang]

450$ for a 185W power supply with 3 channels, a decent line transformer, coolers, an LCD, SCPI control, ... homebrew ?! Naah  You show me !   

Depends if you take time and cost of prototypes into account .

... it only works if you have a negative salary and you capitalize heavily on your lessons learned ...   

[Wolfgang]

450$ for a 185W power supply with 3 channels, a decent line transformer, coolers, an LCD, SCPI control, ... homebrew ?! Naah  You show me !   

Depends if you take time and cost of prototypes into account .

... it only works if you have a negative salary and you capitalize heavily on your lessons learned ...   

[PhilipPeake]

I have a Siglent SPD1168X, delivered this week. Not exactly cheap, although that is a relative term. For what it is, I think its good value. It has things like overshoot under control and does 8A up to 16v, with CV/CC control and remote sense.

If I had to pick fault, it would be that to upgrade the firmware (A PSU as firmware!!!???) unlike most other electronics these days, you don't put the new firmware on a USB drive and upload from there, you have to load it from a Windows machine (no windows? tough luck!), and to do that, you need their remote control app which in turn needs NI-VISA (all 650MB of it). Also, even if you have an ethernet connection working between it and the remote control app, you have to use a USB connection, which requires installing their driver... usual Windows garbage.

Honestly, that seems a bit excessive.

[tautech]

I have a Siglent SPD1168X, delivered this week. Not exactly cheap, although that is a relative term. For what it is, I think its good value. It has things like overshoot under control and does 8A up to 16v, with CV/CC control and remote sense.

If I had to pick fault, it would be that to upgrade the firmware (A PSU as firmware!!!???) unlike most other electronics these days, you don't put the new firmware on a USB drive and upload from there, you have to load it from a Windows machine (no windows? tough luck!), and to do that, you need their remote control app which in turn needs NI-VISA (all 650MB of it). Also, even if you have an ethernet connection working between it and the remote control app, you have to use a USB connection, which requires installing their driver... usual Windows garbage.

Honestly, that seems a bit excessive.

No you aren't required to install the full NIVISA package as the NIVISA Runtime package will support all Siglent equipment functionality and it's heaps smaller depending on which version of Runtime you use.
Sure you still need the EasyPower SW to provide the platform for FW installation.

Connectivity otherwise is normally only required for automated or remote control.

[GlowingGhoul]

R&S HMC/HMP series.

I second this recommendation. These are excellent within their price range.

[tautech]

Well, it's time for me to buy a new power supply for the bench.  And the first question is always "new or vintage" for something like this.  Can I get some guidance here?

I'm looking for something that will provide dual opamp rails (up to at least +/-18V and maybe half an amp, more is better).  A triple output unit would be fine as well, even though I doubt I'd use the 3rd output much, as they are usually 5 Volts.

Good built in metering and adjustable current limit are musts.  Precision and noise are honestly secondary as long as they are 'good enough'.  I really want a useful and clear constant current mode; it would be helpful when troubleshooting shorts with my IR camera.

I have a Tek PS282 from a hundred years ago and it's been just fine, so I'm looking at old PS280's on eBay and I bet it would meet my needs well.  But what about something new?  I think Dave did some reviews of tiny bench supplies, but I have not found the old video yet.

All advice welcome, thank you.

Which way are you leaning on this ?
Is size really a big consideration for a dual or triple channel PSU ?

I'd suggest you take note of what info the front panel/display offers like Set, ON/OFF and actual output, V, A and W.
Some of the triples can be configured for staged ON timing so to manage which rails come up first.

[bson]

My DP832 has served me well for over two years now.  I would like 0.1mA current readout resolution as most modern µC's don't add up to more than a few mA even with LEDs, I2C bus devices, etc.  1mA is a bit coarse and doesn't provide a ballpark sense of power consumption.  But there aren't many bench supplies that will provide that, anyway.  A front connector for the sense input would be nice too, running stuff to a terminal on the back isn't the most convenient.  But for the money, once liberated, it's great value IMO.

[Styno]

What's "decent"?   

For a project I needed a power supply that can deliver up to 50V. I took a chance with a cheap Chinese Wanptek KPS605D 60V/5A bench supply from Aliexpress.

At first sight everything looks fine. It came with a reasonable EU power cable (the mold is a bit rough) but, hey it's from China so let's open it first!

The housing is partially painted metal so it should be connected to the earth wire. Well there is an earth wire and it's properly connected to the big aluminium heat sink plate inside and the heat sink is bolted with two M4 bolts to the metal housing but there is no continuity. Paint between the heat sink and the housing, the usual problem. I added two spring washers between the heat sink and the housing and tightened the bolts back up and now that problem is fixed.

This is worrisome but it could be fixed easily. What worries me as well is that the two rectifier capacitors are rated for 200V and we have 230V AC in Europe so that means the capacitors are subjected to ~330V DC. Way over their rating! The unit functions normally so perhaps they just put two of those capacitors in series? I haven't checked that yet...

The voltage that's displayed is pretty spot on but a bit noisy (100mV@250kHz with all sorts of harmonics, the FFT graph on the scope jumps all over the place with significant and varying peaks up to at least ~5 MHz). Loading it a little bit seems to reduce the noise somewhat.

I can post some pictures if there is interest.