So for a long while, powering prototypes has been a bit of a chore for me, I was constantly wrestling a desktop Kraken of cables. A giant mess crawling out of the umbilical of an old ATX computer power supply, and a couple of wall wart style USB chargers (for powering Arduinos, Phones or Raspberry Pis).
The BK Precision 1550 is a low-cost benchtop power supply that is capable of generating 1 to 36 volts, with an output maximum of 3 amps. It retails for about $135 on amazon. However people outside the U.S. need to be a little careful, the standard model only accepts 100-120V. There is a 220V model (compatible with the mains voltage here in Australia), you just need to hunt around for it, I picked mine up from Mouser Electronics.
I was pleasantly surprised when I unpacked the 1550, it has a really small footprint and is incredibly light. The industrial design of the faceplate is a direct riff on a black iPod Classic, featuring click wheel inspired control buttons and a large back lit LCD screen.
However, just about everywhere else the BK Precision 1550 was good enough, but seemed to agonisingly fall shy of being an amazing power supply. The team at BK had some great ideas in this one, targeting it at the maker/hobbyist/artist/hacker market, but was ultimately held back by small little details/niggles.
For example, the USB charging port drew my attention first. Hopefully I would be able to ditch a few of those wall warts. Unfortunately it has a max output of 0.5 amps. Enough to charge a phone, and run an Arduino. But not enough for the Raspberry Pi/Beaglebone Black. I would be doing my best Jim Cramer buy impersonation right now if BK had sprung for that extra amp and brought the output of the USB charger to 1.5 amps. Running a Pi off the charging port, and simultaneously being able to power a 12 volt circuit the Pi was controlling? Yes Please.
BK also didn’t include any display of the current going out on the charger port, no big deal really and it certainly won’t stop me from using the USB charging port. But getting a breakdown, and able to see total power usage across everything? Hells yes.
For a cheap power supply, it is also accurate enough at +/- 50mV. However, the controls only allow 100mV increments, and the LCD display also rounded the voltage output going out on the banana plugs. This effectively made it impossible for me to configure the the 1550 to read 12.0 volts. Set it to 11.9, and the old fluke gave a read out of 11.94V. Cool. Press the + button once to add (100mV) and the unit read 12.1, and the fluke 12.05 volts. No matter what I did, I couldn’t get the 1550 to land on 12.0v. The output of 11.9 and the 12.1 settings were close enough to 12 volts for my purposes, but it did trip my OCD out a little not being able to get the display to read what I wanted.
Instead of rounding the output voltage, BK could have just used the ceiling or floor values instead. This would create a greater feeling of control over the output, by being able to hit every 100mV increment between 1 and 36V with no appreciable loss in accuracy. Still 12.05 volts coming out, totally close enough to the 12.0 I am trying to get out of the unit. Why not let the LCD display say - hey this is 12.0 volts… Ish?
These are just tiny tiny little details that don’t make this a bad power supply at all. It is a solid unit that is vastly better than the kraken of crap that was sitting on my bench. Overall? 3.5/5.
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