Scotty, I need more power!

Today is Monday, October 11, 2010. What does this mean for you? I’m not sure really… how are you? For me, it means entering my seventh week of job hunting. Actually I’ve been looking for longer than that, but I’ve only been out of school and intensely searching for about seven weeks. Now if you’ve ever been in this situation, you know it gets pretty boring pretty fast. So to help break up the monotony, I’ve been blogging quite a bit and, recently, thinking about all the cool stuff I can buy once I’ve got income again. 😛

You know what I’d really like? A quality benchtop power supply. So far I’ve been working with a simple linear supply which I inherited about four years ago. I think it actually came from a DIY kit. It’s got one fixed 5V, 2A output and two adjustable ±1.5V to ±15V, 1A outputs. Being a linear supply, it’s fairly inefficient. It also can’t do current control, although it does provide over-current and short-circuit protection.

My Current Power Supply (Art Supplied by Author)Now don’t get me wrong, I love this supply. It’s performed with gusto and with fervor, and I certainly couldn’t have accomplished much without it. But as I said, it lacks the ability to perform current control – something I’ve found very useful. It would also be nice to have digital readouts showing voltage and current (since those adjustable knobs aren’t terribly accurate). Now I know I could modify it to perform most of these tasks, but I’d rather use a power supply than build one (despite all the street cred that would get me).

With that in mind, here’s what I’m looking for in my next benchtop power supply:

  • Voltage range of 0-40VDC (or greater)
  • Current supply rated to 5A (or greater)
  • Adjustable current control
  • Digital displays of voltage and current
  • Single output
  • Switching supply preferred for efficiency (but linear is alright)
  • Cost should be under $500

I’ve already located a few suitable candidates; first up is the B&K Precision Model 9110:

B&K Precision 9110

This supply meets all of my requirements, and costs just $275 at Digi-Key. The only exception is that it does not supply its full current (5A) at all output voltages. The diagram above illustrates how this supply is power-limited instead of fully current-limited. So if I want full voltage output (60V), I’ll only be able to draw about 1.7A. This I could probably live with. I also find it interesting that this claims to be a “mixed-mode” supply. So in some ranges it operates as a linear supply, but in others as a switching supply.

Next up is another B&K Precision supply, the new Model 1550 (now with USB charger!):

B&K Precision 1550

This $139 switching supply is good for just 36V and 3A, so it’s a little shy on power. But I had to mention it because of its iPod-like front panel. That new touch pad design and glossy finish make it look remarkably like the iPod Nano (which, conveniently, you could charge with this supply’s USB port). Somehow I doubt I’d use that feature though.

Now here’s yet another B&K Precision PSU, the Model 1743B – a little pricey at $539:

B&K Precision 1743B

This supply provides up to 6A throughout its 35V range and includes two four-digit LED displays. It’s a pretty nice supply, albeit expensive. I’m not sure whether this is a linear or a switching supply, but I’d guess it’s probably linear. That 6A output sure sounds nice…

How about something non-B&K for a change? Here’s the PWS2326 from Tektronix:

Tektronix PWS2326While its voltage rating is a little lower than I’d like (32V), I do appreciate one thing: buttons. No need to fiddle with knobs to get the right voltage and current settings – just type them in! Plus it’ll source 6A, and for $449 it certainly beats the B&K 1743B. It also allows you to return to sixteen different preset voltage and current settings. Again, I kindof doubt I’d ever use that feature, but maybe someday.

One final supply worth mentioning is this beefy Protek model 75005M:

Protek 75005M

This supply certainly meets all of my specs and then some. The prices I’ve found online tend to vary a bit though , from $530 to $630 – either way, it’s definitely on the high side. Plus, I can’t say I’ve ever heard of Protek anywhere. Anyone out there use Protek?


Comparison TableWell right now I’m learning towards either the B&K 9110 or the Tektronix PWS2326. I really like the buttons provided on the Tektronix, but I also appreciate the higher voltage provided by the B&K as well as its substantially lower cost. Of course, until I find work, they’re all out of my price range.

If anyone out there has experience with any of these supplies or would like to suggest another, please leave a comment! Thanks!

Probably just one output would do fine

5 thoughts on “Scotty, I need more power!”

  1. Why don’t you go on eBay, buy the meters you need (and choosing the color ;)) and “hack” (modify) your nice beloved supply ?


    You’ll find plenty of made in China stuff there.

    1. Haha, thanks for that PIClock! I kindof already do this with my multi-meters whenever I need to measure current and voltage more precisely. The trouble is I really want the ability to control current, not just measure it. And I’d really like something nice this time, not hacked… Picky picky, I know. Thanks!

  2. I’ve had good luck with the cheap Chinese bench supplies. I got a dual output 0-30V 5A Mastech supply for < $200 delivered.

    A cousin to this (same total power out, just dual tracking):

    But this seems like it could suit you:

    But if we are willing to accept 0-30V 5A this is much cheaper:

    1. Excellent, thanks! I’ve actually used a model almost identical to the 0-30V, 5A supply you mentioned. It worked well most of the time, but tended to get confused when used to drive certain motors (probably thought it was seeing a short). At one point this caused a minor injury in the lab when the supply suddenly decided to enable itself, causing an arm attached to a motor to whip around and whack a guy’s hand.

      This Instek supply you mentioned ( looks really good actually. Not only does it meet all my specs and cost just $279, but it has a constant power output as well! Pretty cool. Thanks!

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