Review: MPJA 9615: 0-30 volt, 0-3 Amp, Bench Power Supply

a small bench powersupply. Two knobs for volts/amps, and an on-off switch plus an LCD display.
This is the MPJA 9615ps mini-bench power supply. The specs say that it will provide 0-30 volts and 0-3 amps. Mine actually goes up to 31.6 volts (displayed, measured to 31.3 volts on my lowest DMM) and has driven a short at 3.25 amps (verified with my DMM). As the previous sentence alludes to, the voltage display on my unit was 0.3 volts higher than my $50 Chinese DMM, and 0.1 volts higher than my $14 Chinese DMM. Given that my two DMMs don’t quite agree, I’m not willing to say anything other than the fact that I think it’s accurate to at least 0.3 volts. [The amp readings matched those on my DMM’s.]

Pros:

  • The unit is nice and small.
  • The black on white backlit LCD is easy to read.
  • The price…this sucker costs $50!

Cons:

  • It doesn’t have a switch to turn off the output, so if you want to adjust it to a specific voltage before applying power, you have to disconnect it from your circuit, set the voltage, and then connect it to your circuit.
  • The knobs set the maximum voltage/current, but the LCD does not display the set value unless you are at the limit. So it typically displays the voltage set point (if the load is voltage limited), and if you want to set the current to a specific amount (higher than is currently being drawn) you’d have to short the leads or connect it to a dummy load. If you want to set the current to what the load draws or limit the current draw, you can start it off at zero and move it up until it hits the value you want.
  • The banana jacks to alligator clips the unit ships with are cheap. Notice those screw heads in the picture on the jacks? They are energized, so don’t touch!
  • The fan on the back runs continuously. It is not a terribly loud fan, but it is audible. (Think a laptop GPU fan that kicks in when you run a video game….except it never turns off.) This doesn’t bother me, but I wouldn’t leave the PS running all day either.

All in all, I’m happy with my purchase. This supply does what it’s supposed to and makes it easy to power circuits and monitor their power consumption. It makes a great inexpensive hobbyist bench supply, or a 2nd supply for a professional who just needs to power something.

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