Questions as I ponder bench supplies (SPD3303X-E vs TP3005D-3 vs other)... - Page 1
Forum section: electronics / testgear

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 06, 2019, 02:37:35 am
content: I'm considering theSiglent SPD3303X-Evs theTekpower TP3005D-3(and potentially "neither" - floating outputs would be handy so I don't think the Rigol DP832 is a contender here).I'll preface with the meta-question of whether a switching power supply would be a viable option? (I doubt it but it's worth asking.) Linears are big and no doubt power-hungry (but no switching noise!). I really don't want to spent over $500 USD for this (if anything near it).Specific questions then:- 3A (Siglent) vs the 5A (Tekpower) - I'm always in favor of more power, but how often does it really matter in your (very subjective) experience? I don't foresee having a need for over 30V, but I can imagine times where 5A would come in handy.- Overshoot - I understand the Tekpower has voltage excursions on power-up, and that the Siglent doesn't. Is that a common problem? Not having that possibility is one less thing to worry about.- Noise (including induced noise in nearby things) - both appear to use toroidal transformers so that helps, but is one significantly more noisy than the other within their overlapping current ranges?- Mass - is it simply a fact that a triple 5A unit will weight significantly more than triple 3A unit? The Tekpower appears to be 50% heavier than the Siglent, which seems to be a bit much.- Connectors - I understand the Siglent's plug spacing isunique, but the loose connections seen in the EEVBlog review are no longer an issue, correct?- Quality, including knobs, buttons, and switches - Any complaints there? I like the fact that the 3rd output is switchable, as long as it's a solid switch.The Siglent is certainly nicer in terms of features (programmable), and it's...not impossibletoenable a higher precision mode.(Curious if anything else is upgradable, but that alone would be worth the effort.)The Tekpower sells me on having more power and a solid design, and of course a lower price, but I'm not sure I'll need 5A (beyond a certain point I use fixed supplies to do the job anyway). I also would prefer not to waste precious bench space, and what space is used ought to be occupied by something decent... like Siglent.Thoughts?All things being equal, the Siglent seems like the better choice within my budget (but only 3A vs 5A). But if it's got quality issues or other quirks I'm unaware of I may have to go back to the drawing board on this whole thing.

author: tautech
author_rank: Super Contributor
timestamp: January 06, 2019, 02:55:18 am
content: Thoughts ?Have you seen their single rail psu’s ?Very good ripple specs.https://www.siglentamerica.com/power-supplies/spd1000x-series-programmable-dc-power-supply/

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 06, 2019, 03:42:24 am
content: Quote from: tautech on January 06, 2019, 02:55:18 amInteresting - the SPD1305X does have slightly less ripple (and clearly higher current), though to get just a dual output setup I'd need two of these (they're also hefty, and the total cost would be higher). I wonder what happens to the noise and ripple if you connect two in series/parallel?Edit: The sense terminals are a nice touch. I'm not sure it justifies the price tag (or the space requirements) for me though, but I'm giving it due consideration.

author: tautech
author_rank: Super Contributor
timestamp: January 06, 2019, 05:19:22 am
content: Take a look at the 8A 16V unit I lent Defpom.....and rather than return it he bought it.

author: DaJMasta
author_rank: Super Contributor
timestamp: January 06, 2019, 05:28:53 am
content: The high current can be useful for certain kinds of things, but if you really need it, you can turn on parallel mode on the SPD3303X-E and get 6A between the two paralleled primary channels and your side logic voltage. Otherwise, 3A on each rail is a hell of a lot of juice for regular logic/analog projects... if you need to power heaters, large motors, bright lights, etc. then the extra current is going to be important, but for solid state circuitry there's not much of a need. Its rare I have my current limit per channel anywhere near 3A unless I'm working with something higher power... in which case having a clean, well regulated supply is often less critical.If you're not working in analog circuits much, though, having a split supply may not have much value, in that case, a single channel higher current supply is probably best for your use case. A triple is especially good for having a negative rail and tying the two primary floating outputs together to get it, while it can be handy to have something like 12V, 5V, 3.3V on a single power supply, with a couple of regulators you could easily get that from a single supply (albeit with a decent heatsink on the low rails if you've got a lot of current going) - there are probably use cases for powering up boards designed for multiple output external supplies, but I find the big benefit of a triple is an analog split supply alongside a digital rail, so if you don't need the negative, maybe going with a high power single channel would be more appropriate.

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 06, 2019, 05:56:03 am
content: Quote from: tautech on January 06, 2019, 05:19:22 amIt's a consideration, though I'd be inclined to go for the 5A 30V unit of the same line if I went down that road.The sense input is interesting to me, though I'm not sure I'd make that much use of it.Quote from: DaJMasta on January 06, 2019, 05:28:53 amThis to both of you: I'm dabbling in analog and having at least dual supplies would be advantageous precisely for split-rail purposes. That's why I'm more inclined to first get a dual/triple (the extra channel on the triple seems almost an afterthought in terms of its limitations, but it'd be nice to have nonetheless). Sounds like 3A should be plenty for general purpose and learning, and if I really need a more powerful single supply I can always plunk down for a SPD1000X series device with a higher current rating.Bottom line: I want at least dual rails, preferably programmable, definitely stable, and reasonably low-noise. Three rails is a nice bonus, but good construction is a must. As I suspect this will be my primary bench supply, having all this in one unit (versus two) to accomplish this would be preferable as well.Question 1: On the topic of noise: Is the SPD3303X-E too noisy, or just not quite as good as that of the SPD1000X series but good enough in general?Question 2: did Siglent finally resolve the binding post problems or not?I thought they did but now it's not clear if they changed the posts in production or if people just hacked around them...

author: tautech
author_rank: Super Contributor
timestamp: January 06, 2019, 06:06:20 am
content: #1. Both units use quiet smart fans and unless you’re drawing lots from them you won’t hear them !#2. The binding posts AFAIK are still 20mm centres however they have been changed in the SPD3303X/X-E so that the conductor is not so recessed.Away from base for another couple of days to double check the centre spacings of SPD1kX models for you.BillB might measure his.

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 06, 2019, 06:38:04 am
content: Quote from: tautech on January 06, 2019, 06:06:20 am#1. I meant electrical ripple and noise - while the single-supply units are less noisy/ripply, I wonder if they would do as well in a dual rail configuration, versus the main two rails in the triple-supply? (Good to know the fan noise is low though, regardless!)#2. My concern was the problem of plugs not staying in - I don't think the spacing ever changed and I'm not that worried about that bit.

author: DaJMasta
author_rank: Super Contributor
timestamp: January 06, 2019, 08:10:22 am
content: As said, the spacing is non-standard, but the binding posts are alright. There was a thread complaining about them not being deep enough earlier and redoing them... but while there were some very early units with actually loose ones, I think I've got the not deep enough ones and they've worked just fine for all of my cables.I can confirm that the supplies can be very, very soft, since the fan won't even run (or will do so inaudibly) at lower power settings, and it's certainly not bad at full tilt. There are a couple goofy UI quirks - the current version shows the set voltage/current and the measured, which is great, but it means that the fonts are a lot smaller than early versions that showed set levels until you turned the outputs on. The navigation between values is just counterintuitive, they have a left and right arrow that you'd expect to change digits to use the encoder wheel, but instead they change between voltage/current/etc. while the "fine" key changes the digit in the setting, and only in one direction. The third rail is also only controllable with a switch and has no readout for current or voltage, though the regulation seems to be accurate, which is really it's only nick when comparing to the Rigol DP832 in my opinion.With a triple that does parallel and series modes, like the SPD3303X-E, you get the basic 3A triple supply, or you can switch over to a "dual" supply mode and get either normal voltage to 6A (parallel), or to 60V at 3A. Not quite the same as a second supply so you can have both at once, but a fair amount of flexibility. It's also easy to unlock to the regular X version with 1mA/1mV resolution and regulation - just download a modified current firmware version (found in a thread here) and flash it over USB using the easypower application - worked great for both of my units and very quick to do.

author: tautech
author_rank: Super Contributor
timestamp: January 06, 2019, 08:15:20 am
content: I’d need to check with tech support for series and parallel of 1kX units so I think the 3303 model will suit you requirements better.On the binding posts see here:https://www.eevblog.com/forum/testgear/siglent-spd3303x-e-binding-post-issues-solved/

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 06, 2019, 08:26:16 am
content: Quote from: tautech on January 06, 2019, 08:15:20 amI've been giving that post a long read, just wasn't clear they resolved it for sure (seems likely they did though). I have some learning to do re: banana plugs and the wiring thereof (I see recommendations of the soldered kind - I thought that would lead to potential mechanical problems at the solder joint though....Edit: Already learned this:I'm still leaning towards the 3303 but will sleep on it and all before I order anything. I've got about everything else I could reasonably want for my bench save a good PSU like this (and the TP3005D-3 I originally also mentioned seems a distant second for my purposes).Thanks again!

author: colorado.rob
author_rank: Frequent Contributor
timestamp: January 06, 2019, 03:44:09 pm
content: I have a Mastech branded version of the TekPower supply you are considering. It has one major problem for me. I do RF work and occasionally there are strong RF fields in my lab. The Mastech supply behaves badly around strong RF fields (poor EMC). It changed voltage settings and fried DUTs twice due to such misbehavior before being retired. I would not connect anything of value to that PS.

author: nctnico
author_rank: Super Contributor
timestamp: January 06, 2019, 04:24:51 pm
content: If you uphack the Siglent SPD3303X-E then I think it is a good buy considering your budget. It has been out there for a while and they seem to sell lots of them so any issues should be ironed out by now. A programmable power supply which can step through voltages can be handy every now and then.

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 06, 2019, 08:00:07 pm
content: Quote from: colorado.rob on January 06, 2019, 03:44:09 pmThat's rather scary, and enough to steer me away from that line entirely. I wondering if the Siglent is better in that regard?

author: BillB
author_rank: Unknown
timestamp: January 06, 2019, 11:28:47 pm
content: Quote from: tautech on January 06, 2019, 06:06:20 amI can confirm the spacing on the SPD1168X supply is correct, and dual banana plugs fit fine.

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 07, 2019, 02:07:06 am
content: Quote from: nctnico on January 06, 2019, 04:24:51 pmI'm still pondering whether 5A is worth buying two of the SDP1000X types instead. Seems it'd be cumbersome to try to gang two of those together though. I'll probably end up getting the SPD3303X-E (and of course immediately uphack it)... now to find some good cables (or make my own...)

author: Leiothrix
author_rank: Regular Contributor
timestamp: January 08, 2019, 11:25:49 pm
content: Also compare physical size. I bought the Siglent SPD3303X-E over the Rigol equivalent because the Siglent would fit in the space I had for it and the Rigol would not.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: January 09, 2019, 04:00:39 pm
content: Not sure about floating outputs but I think you could remove the input earth on the DP832 to get it to have 'floating outputs' (cue purists telling me that I'm advocating suicide, do it at your own risk). I own the SPD3303X-E and the DP832 and prefer the Rigol. On the Siglent, the 3rd output has no display other than an LED saying it's on and worst of all, it's only got a 2.5/3.3/5V control switch which is easy to knock accidentally as it's right next to the binding posts and the current is a fixed limit of 3.2A which can't be changed - that means that it practically useless for unknown circuits because you can fry most things with 3.2A. My Siglent also has looser binding posts than the Rigol and that's after I modified them.The Rigol has the disadvantage that outputs 2 & 3 share the same -ve potential but that's clearly indicated on the front and I haven't had a situation where that has stopped me using all 3 supplies on the same PCB. The DP832 also has full display and control of set, actual, limit voltage and current for all 3 channels.The rigol has a color display but you only pick one color which is mildly annoying, the use of colors on the SPD3303X-E is better.Both can be 'upgraded' to higher resolution.If I could only keep one, it would be the DP832

author: Calvin
author_rank: Regular Contributor
timestamp: January 09, 2019, 05:34:40 pm
content: Hi,I'm a happy user of the Siglent SPD3303C, which is the X-E's smaller and consderably cheaper brother.It only differs in the fancy display and onboard programmability and cannot be 'upgraded' to the higher precision X-supply. Its progamnable via sftware though and the 'power stuff' inside is the same.It may be an alternative to buy 2 of the SPD3303C for up to 2x64V/3.2A or 2x32V/6.4A for the roundabout price of 1 SPD3303X.regardsCalvin

author: nctnico
author_rank: Super Contributor
timestamp: January 09, 2019, 05:44:27 pm
content: Quote from: Gandalf_Sr on January 09, 2019, 04:00:39 pmBut judging from the DP832 thread this Rigol PSU also has a few bugs (including power-on overshoot and random reboots) which aren't fixed by Rigol. Maybe it is better to spend more money and buy a PSU from Keysight which doesn't have all these drawbacks.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: January 10, 2019, 01:53:32 am
content: I never came across any firmware bugs or experience reboots on my Rigol DP832. The fan was noisy and I replaced it - there's info I posted on that somewhere here.

author: nctnico
author_rank: Super Contributor
timestamp: January 10, 2019, 06:49:27 am
content: Quote from: Gandalf_Sr on January 10, 2019, 01:53:32 amThen you seem to be very lucky. Others are not.

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 10, 2019, 07:44:37 am
content: My Siglent will be here next week - not overshooting was a big factor, as was the form factor and versus cheaper ones, the quality. Hackability was also a plus.The fixed (switchable) output will IMHO come in handy - to me it's a bonus feature that will save a wall-wart for 5V or 3.3V (not quite sure what 2.5V is useful for). A bit of tape or blu-tack will keep it in place if it's too easy to switch.I ordered up what seemed to be an OK set of banana leads, but also some silicone wire for making better leads. Will get some good plugs to go with them when time permits.

author: nctnico
author_rank: Super Contributor
timestamp: January 10, 2019, 10:37:09 am
content: Hirschmann has very nice stackable silicone banana leads which aren't expensive. Making banana leads yourself is hardly worth it.

author: BillB
author_rank: Unknown
timestamp: January 10, 2019, 05:19:57 pm
content: Quote from: MartyMacGyver on January 10, 2019, 07:44:37 amIt would have been nice if the 3rd output was more integrated, but I also just treat it as a supply for limited, well-known circuits/devices. I don't think you'll need to worry about the tape on the switch. The switch takes a bit of force to move, so I think the concern about accidental switching is overblown unless you are really ham-fisted.

author: bitbanger
author_rank: Regular Contributor
timestamp: January 10, 2019, 05:40:21 pm
content: You can occasionally pick these TTI's up on fleabay for ~$200USD + shipping. Rock solid, basic programming ability (some models) if you really need it. I have a Rogol DP712 and this gets more use.I wouldn't consider a multi-channel PSU that didn't allow you to set current w/out manually shorting the output. Same goes for channel control - call me lazy but I prefer the ability to turn on/off individual outputs vs unplugging the banana.PL330DP

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 10, 2019, 06:42:16 pm
content: Quote from: nctnico on January 10, 2019, 10:37:09 amI was looking at Hirschmann - they're USD10 each, plus an extra USD20 as a "freight" charge (Newark). Pomona may be a better option for where I am (US), but either way I'm keeping things flexible til I know what exactly I need (only a few things I have use banana plugs, and the voltage drop over the typical 18AWG-22AWG wiring used for these is more than it would be with the 14 AWG write I got).It is odd to me that so many of the plugs out there (even the not-cheap ones) use the "spinning" spring plug design. Not sure why that's common or popular (doesn't seem like it's particularly economical). That's one thing I like about the Hirschmann ones... and why I'm considering buying their plug ends to be able to make custom lengths using a better gauge of wire (14AWG).

author: MartyMacGyver
author_rank: Regular Contributor
timestamp: January 15, 2019, 05:26:42 am
content: FYI, I received my 3303 today - it immediately led to a question I hope to get clarity on before I put the box in storage (versus have it repaired, if there's actually a problem indicated). Odds are it's fine but I want to be sure:https://www.eevblog.com/forum/testgear/spd3303x-e-(unmodified)-curious-behavior-when-outputs-are-on/