Let's talk about "Decent cheap Bench Power Supplies", OK? - Page 1
Forum section: electronics / testgear

author: cvanc
author_rank: Frequent Contributor
timestamp: August 22, 2018, 01:05:26 pm
content: 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.

author: BillB
author_rank: Unknown
timestamp: August 22, 2018, 01:13:45 pm
content: What is "good enough" precision?Do you need timers, or remote programming?Do you need 4 wire sensing?Physical size - tiny? Any actual physical size requirements?Display requirements?Most importantly, budget?

author: bd139
author_rank: Super Contributor
timestamp: August 22, 2018, 01:15:15 pm
content: E36311A.Get saving

author: KaneTW
author_rank: Frequent Contributor
timestamp: August 22, 2018, 01:19:17 pm
content: R&S HMC/HMP series.

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 22, 2018, 01:31:45 pm
content: Quote from: bd139 on August 22, 2018, 01:15:15 pmThat's decent but not cheap.

author: DaJMasta
author_rank: Super Contributor
timestamp: August 22, 2018, 04:16:01 pm
content: So far, with your search criteria, the playing field is still very broad.I would go with a triple output supply, at least, since a pair of isolated outputs can give you a split rail and even if the third output is just a logic level supply, that can really come in handy (and is good as a digital rail even when you're doing mostly analog work with the other channels).There's the cheap ones, the sort of midrange cheap ones, and then the more expensive ones. Plenty of reviews around on the first two broad categories, but I tend towards recommending a couple notches above the bottom of what's acceptable, so I'd look around at the SPD3303X-E and the DP832 (and of them, I personally think the Siglent is better value, though the third rail is less adjustable and does not have a current measurement). If you want a bit less power noise/more accuracy, then the E3631A will suit your requirements (and is around the same price used), just with a fraction of the output power and a VFD display which only can show information about one channel at a time.There are plenty of alternatives, and even some in that general price bracket.... so any further requirements?

author: Fungus
author_rank: Super Contributor
timestamp: August 22, 2018, 04:36:21 pm
content: Quote from: Mr. Scram on August 22, 2018, 01:31:45 pmAround here? You only get to pickoneof those.

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 22, 2018, 06:08:02 pm
content: Quote from: Fungus on August 22, 2018, 04:36:21 pmI don't agree, though it does depend on your specific demands. If you need to do precise measurements you'll end up with something else than when you just need power that's not super noisy and ballpark accurate without burning your place down.

author: technogeeky
author_rank: Frequent Contributor
timestamp: August 22, 2018, 07:20:28 pm
content: I have been super happy with my GPD-3303s. It's 0-32 volts, 0-3.2 amps, with a selectable [2.5, 3.3, 5.0] volt, 3.0 amp output as the 3rd supply.I got mine from eBay for $175. I've seen them go as low as $150 and as high as $225. It's pretty clean (though it does have thermal drift). The 3rd supply has some overshoot problems which can be fixed (there's a thread about this).Dave did a video on essentially the same supply but with an updated display from Siglent here:

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 22, 2018, 08:05:13 pm
content: Quote from: technogeeky on August 22, 2018, 07:20:28 pmOne thing it lacks is remote sensing, which may be relevant if you require that accuracy.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 22, 2018, 08:33:15 pm
content: For the supplies i'm an old geek, i love any linear supplyHad fun trying an few switching models, but some of them lack inductive loads tolerance / acceptance, had this week an Mastech HY3010E-2 who had the main mosfets circuit blown because of the incredible build quality pfffI have an Kepco ate 75-8 who has been beaten a lot and never failed me, sure the linear supply are bulky and heavy, but they are tougher for my need@cvanc : Evaluate your needs, check feed backs and problems and get an service manual first before you buy something .... may help in the future, you never know.

author: nctnico
author_rank: Super Contributor
timestamp: August 22, 2018, 10:07:25 pm
content: Quote from: bd139 on August 22, 2018, 01:15:15 pmI ended up buying the Keysight E36313A but the other one on the short list was a GW Instek GPE-2323. It depends on whether you need a lot of bells and whistles like remote control, voltage/current logging, step through current / voltage settings, etc.

author: David Hess
author_rank: Super Contributor
timestamp: August 22, 2018, 11:52:28 pm
content: I like the old Tektronix PS503A but it requires a TM500 mainframe. HP made a whole series of suitable power supplies like the E3620A and E3631A which would be suitable.

author: rhb
author_rank: Super Contributor
timestamp: August 23, 2018, 12:22:22 am
content: I bought an Instek GPE-4323. Price was good for a linear supply, it's got 4 adjustable outputs. Current limiting on C1 & C2. Just voltage on C3 & C4. My sole complaint is that setting the limits is fiddly because they used a pot rather than an encoder. And the banana jacks are very close together. So clamping a wire or lug is difficult. But it's not an issue with banana plugs.I've used it as a current source measured with a 34401A and it did a good job of holding the current I set to uA levels. Not that I could set it that closely. Just that it held what it was set to that closely.

author: rsjsouza
author_rank: Super Contributor
timestamp: August 23, 2018, 12:48:52 am
content: If you don't care for modernities, aTP340Aor aTW5005Tmay fit the bill. Actually, most anything from Power Designs, really (2020, 2050, etc.)

author: JXL
author_rank: Regular Contributor
timestamp: August 23, 2018, 06:18:52 am
content: 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.The 6236B has a "twin", Leader LPS-151 and it's higher output current sibling LPS-152. These last 2 have current limiting controls on the front panel.The manuals with circuit diagrams for them are available on the net.

author: exe
author_rank: Unknown
timestamp: August 23, 2018, 07:39:06 am
content: Let me be a rebel in this thread, I propose Rigol DP832. I myself don't have it, but reviews are positive. Not ideal, but I'd buy it if I needed a PSU. But I have three DIY power supplies and slowly building the forth one.There are other options from siglent, gw-instek, etc, worth checking them. Just be sure to check for overshoot issues. Other things that worth paying attention: (acoustic) noise, power consumption when it's off, firmware stability, 115/230V switch (or 90-264V operation), ease of use (ergonomics), number of channels (I suggest not less than 2).

author: nctnico
author_rank: Super Contributor
timestamp: August 23, 2018, 08:10:38 am
content: By the way: I would recommend against getting a switching power supply unless you need a lot of power and/or small size / light weight. Their outputs are quite noisy and they usually inject some HF noise into the outputs as well.

author: bd139
author_rank: Super Contributor
timestamp: August 23, 2018, 08:27:18 am
content: Quote from: JXL on August 23, 2018, 06:18:52 amHad both of those HP supplies before. Very nice units. Hard current limit is effective however. Didn't blow anything up with themFor many years I used a 7Ah 12V SLA as a power supply with a series resistor in circuit to limit TBH. Worked fine and if anything went wrong the resistor went up in smoke instead.Worth looking out for Thurlby / TTi PL320QMD / PL330QMD as well. Big but run at full whack with just passive heatsink. I have two of the single units at the moment.

author: Wolfgang
author_rank: Super Contributor
timestamp: August 23, 2018, 12:31:27 pm
content: Hi,I have a lot of lab PSUs, and the Rigol DP832 is the one I use most. Reasons:- good range (2x33V/3.3A, 1x5V5A)- fairly stable and accurate (10mV)- current mode works- computer controllable if needed- good readouts- there is an "A" version if you need more gimmicks and precisionWhy not try one ? My dealers offer a 30 days no reasons asked return policy.

author: rstofer
author_rank: Super Contributor
timestamp: August 23, 2018, 02:24:08 pm
content: Quote from: exe on August 23, 2018, 07:39:06 amI bought the DP832 a while back and I like it a lot. The current limiting alone is worth the cost of entry. I was bringing up a little Z80 project and I had an address conflict causing two devices to drive the bus simultaneously. Without current limiting, this would have been a disaster. As it worked out, the supply limited, the voltage dropped and nothing was damaged.It's a really nice supply but it isn't inexpensive. However, when you consider the lifetime of the supply (multiple decades, I suppose), the cost per day is insignificant. It's the 'ouch' to the cash flow that hurts.Even with the cost, I think it is a better solution than trying to build up multiple DIY supplies. The DIY supplies just don't have the features and a workable current limit is one feature I want, regardless of cost.It's also nice to be able to see both the setpoints and the outputs. There's a lot of information on the screen and it is all helpful.

author: exe
author_rank: Unknown
timestamp: August 23, 2018, 04:42:06 pm
content: Quote from: rstofer on August 23, 2018, 02:24:08 pmAre you attacking my power supply?Ha-ha, not just my psu has a current limit, it also has just an 10uF output capacitor. Compare with what you have in dp832.

author: Wolfgang
author_rank: Super Contributor
timestamp: August 23, 2018, 04:58:53 pm
content: Yeah, agreed. Of yourse you can do better than a DP832, but not for the same bang for the buck.450$ for a 185W power supply with 3 channels, a decent line transformer, coolers, an LCD, SCPI control, ... homebrew ?! NaahYou show me !

author: exe
author_rank: Unknown
timestamp: August 23, 2018, 05:05:38 pm
content: Quote from: Wolfgang on August 23, 2018, 04:58:53 pmDepends if you take time and cost of prototypes into account.

author: bd139
author_rank: Super Contributor
timestamp: August 23, 2018, 05:09:28 pm
content: You're not going to get a homebrew one for less than that. Even if you discount labour it's pushing it.Heatsinks, transformer and enclosure are the most expensive bits TBH and I reckon for something equivalent you're looking at $300 min.Build vs buy is an easy decision these days. Buy is 99.9% of the time cheaper.

author: GregDunn
author_rank: Frequent Contributor
timestamp: August 23, 2018, 05:25:36 pm
content: Quote from: JXL on August 23, 2018, 06:18:52 amWe 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.

author: bd139
author_rank: Super Contributor
timestamp: August 23, 2018, 06:42:44 pm
content: 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

author: exe
author_rank: Unknown
timestamp: August 23, 2018, 07:00:35 pm
content: Quote from: bd139 on August 23, 2018, 05:09:28 pmIt'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.

author: bd139
author_rank: Super Contributor
timestamp: August 23, 2018, 07:21:08 pm
content: Quote from: exe on August 23, 2018, 07:00:35 pmExactly. I know when to stop. These were £40 each (~$50)

author: exe
author_rank: Unknown
timestamp: August 23, 2018, 07:44:22 pm
content: 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.

author: bd139
author_rank: Super Contributor
timestamp: August 23, 2018, 08:09:49 pm
content: 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

author: exe
author_rank: Unknown
timestamp: August 23, 2018, 08:26:19 pm
content: Quote from: bd139 on August 23, 2018, 08:09:49 pmYou 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.

author: bd139
author_rank: Super Contributor
timestamp: August 23, 2018, 08:45:50 pm
content: Quote from: exe on August 23, 2018, 08:26:19 pmYeah 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.Quote from: cdev on August 23, 2018, 08:41:19 pmSorensen ones are actually TTI ones that are rebranded. TTi stuff is top quality stuff actually made in UK

author: Wolfgang
author_rank: Super Contributor
timestamp: August 23, 2018, 08:46:03 pm
content: Quote from: exe on August 23, 2018, 05:05:38 pm... it only works if you have a negative salary and you capitalize heavily on your lessons learned ...

author: Wolfgang
author_rank: Super Contributor
timestamp: August 23, 2018, 08:47:09 pm
content: Quote from: exe on August 23, 2018, 05:05:38 pm... it only works if you have a negative salary and you capitalize heavily on your lessons learned ...

author: PhilipPeake
author_rank: Regular Contributor
timestamp: August 23, 2018, 10:33:28 pm
content: 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.

author: tautech
author_rank: Super Contributor
timestamp: August 23, 2018, 10:45:49 pm
content: Quote from: PhilipPeake on August 23, 2018, 10:33:28 pmNo 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.

author: GlowingGhoul
author_rank: Regular Contributor
timestamp: August 23, 2018, 11:51:44 pm
content: Quote from: KaneTW on August 22, 2018, 01:19:17 pmI second this recommendation. These are excellent within their price range.

author: tautech
author_rank: Super Contributor
timestamp: August 24, 2018, 10:22:19 pm
content: Quote from: cvanc on August 22, 2018, 01:05:26 pmWhich 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.

author: bson
author_rank: Unknown
timestamp: August 25, 2018, 01:27:34 am
content: 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.

author: Styno
author_rank: Regular Contributor
timestamp: November 23, 2018, 09:04:48 am
content: 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 fromAliexpress.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.