Advice on bench-top power supply - Array 3645A, Rigol DP-832, TENMA, GW INSTEK?

[DavidA]

I'm looking for a bench-top power supply to support my electronics hobby (which becomes somewhat professional from time to time). So far I've managed to get by with fixed voltage DC supplies and a bunch of either hand-made or kitset linear regulators, but I could really use a single, stable, reliable constant voltage and constant current source. I tend to do digital electronics, micro-controller stuff, so 3-5A at 0V to 12-18V is probably fine for me. A built-in voltage/current meter (especially the current meter) would be nice, but I don't see that on any of the lower cost units at all. I've read that linear is better than switch-mode but I don't 100% understand why (noise perhaps?). Settable current limiting would be very useful.

Unlike almost all the other similar threads on this topic, my problem is one of location. I simply don't have access to the full PSU market. I live in an island country (NZ) where everything except scenery is expensive or unavailable. What's more, importing heavy new things like power supplies from overseas is very expensive. This makes buying such things on eBay impractical, generally. It also means that most brands are not stocked by terrestrial stores, and in most cases they are unwilling to place special one-off orders. The NZ population is small, and demand for this kind of equipment is almost zero. There's very little in the second-hand markets. Most unfortunately, shipping from Australia is more expensive than from the UK or USA. Anyway, this leads me to often go via commercial channels.

One such channel has offered me an Array 3645A PSU for around NZ$450 (about US$300), discounted from NZ$675. This is a rebadged CircuitSpecialists CIS3645A I believe. It's a linear PSU and I understand the fan isn't overly noisy. A bonus is that it is programmable, which could be useful to me as I do automate things from time to time.

I've also been offered the Rigol DP-832 for NZ$1050 (about US$700), which seems very steep to me, but it's the only place I can get one without having to import it myself (plus taxes & duty & customs hassle). Three independent supplies would be useful sometimes, but I do suspect I'm attracted by the what-ifs rather than what I actually need.

There's a local store called Jaycar (NZ version, similar to the Australian one) that sells generic (usually unbranded) power supplies like this but I suspect it's massively marked up (from prior experience of Jaycar) and probably just a generic cheap one.

So that brings me to the "TENMA" brand. I can get these through Element14 - and they are significantly cheaper. For example, I could order the 72-2685 for NZ$112 (US$75). It's much lighter on features but at the price of the 3645A I could buy two, or even go for a higher-spec model. However I've read on this forum that TENMA is not a favoured brand so I'm uncertain about these. Can anyone vouch for them?

I want to buy something that will last 20+ years (I look after my stuff) and remain useful indefinitely. So I'm happy to pay for the 3645A if it's a good deal, but I do wonder if there are better options for that kind of budget. For example, the GW INSTEK GPS-1850D is cheaper (NZ$330), and for a bit more than the 3645A I could get a higher-spec'd GW INSTEK.

I've also considered building my own - I think it's within my capabilities. The problem I have at this point in my life is time - I have a lot to get done already, and building a PSU isn't going to fit well into my schedule. I'd rather invest in something solid and rely on it for, ideally, the rest of my life.

[bob91343]

I understand and empathize.  One of the things that is hard to measure is reliability.  You want this unit to last many years but frankly there is no way to estimate that.  I have had cheap units last many years and expensive ones break early in life, so my suggestion is ignore this aspect.

From reading your post quickly, I would think your best recourse is to go for the Tenma.  If it fails, well you can afford to buy another or eat the cost as a lesson.  If you treat it properly, it's likely to hold up.  Make sure you get the documentation so that you can repair it if needed.  The main concern would be the power transformer, so maybe you'd be well advised to buy two units and keep the second one as backup.  That way, in five or ten years, should you need to replace the transformer, you will have one rather than having to agonize over finding an obsolete part.

And to treat both units well, rotate them from time to time.  That way if one deteriorates you will know immediately.

I own many power supplies and haven't had to repair them recently.  I did some repair perhaps 40 years ago but they have held up since.  In fact, I got them because they didn't work properly and it didn't take a genius to see what the previous technician missed.  One in particular was given to me as a dead unit but it worked fine.

Go to swap meets.  I find them an excellent source of gear and parts, even though they areen't the exact type I was seeking.  In the long run you accumulate lots of gear and usually have what you need.  You can't beat the price, especially since much of my lab is represented by gear that has been given to me free.

[MarkF]

I don't know if these are available for you...
Have you seen these:
   Siglent SPD1168X 16V @ 8A $259USD
   Siglent SPD1305X 30V @ 5A $279USD

[Dabbot]

Linear power supplies produce less ripple than switch-mode, but also more expensive and larger / heavier.

Given that you're doing mainly digital work, a switch-mode power supply will be fine.

[rstofer]

User Tautech here on eevBlog is the Siglent rep for New Zealand.  You might try to PM him if he doesn't show up on this thread.

[DavidA]

Thanks everyone for the responses. I'll have a think about what you've said. I've actually emailed Tautech about those Siglent units, since he's the NZ distributor, so they may be an option.

Does anyone have hands-on experience with the Array 3645A? I believe it also sold in the US as the CSI3645A.

Dabbot - thanks for the note on switch-mode, I'll consider those too.

[LogicalDave]

For others interested in the Array 3645A (aka Circuit Specialists 3645A), someone did a good review (and found a concerning problem) here:
http://eereview.com/article/array-3645a-power-supply-review

In a nutshell, the supply does switches between two ranges: <4V and >4V and there is a serious overshoot issue when crossing the 4V mark under some circumstances.  If anyone is aware of this being fixed (or a fix for it), please reply with the specifics.  Thanks!

[wizard69]

This sounds like an excellent opportunity to start an import business or even get into local electronics manufacturing.

That might not be your cup of tea so I can only suggest choosing a power supply that has the features that meet your needs.   It doesn't sound like you will get much support if something goes wrong no matter what you choose.   I'm resisting asking if HP/Agilent/Keysight/Whatever (but what the hell), if they have an office in your country.   The prices would likely be ridiculously expensive.