Extech 382260 80 Watt Switching Mode DC Power Supply Review

Average Reviews:

(More customer reviews)I picked my Extech 382260 at Frys Electronics for a very reasonable price. I had hoped for the perfect bench power supply until... I turned it on and took it for a ride.
PROS
Small, cutely designed, lightweight, 4-digit LED panel meters, output control with rotary switches instead of potentiometers.
CONS
Major lack of precision in the settings of output voltage and current limit.
The 4-digit panel voltmeter displays two digits after the decimal point. And with the rotary switch one should be able to set output voltage with great accuracy, right? Wrong! Each click of the rotary switch increases the voltage by leaps of 0.12 to 0.29 Volts.
Here are my results (in Volts) of turning the voltage knob 8 clicks: 0.01, 0.17, 0.28, 0.39, 0.52, 0.63, 0.76, and 1.05. It was impossible to set any values in between.
Setting over-current protection looked like this: 8 clicks of the current setting knob resulted in the following milli-Amp values, 5, 27, 34, 43, 50, 64, 66, and 75. Again, forget about setting any value in between. Then, at about 12 Volts output I used Fluke 117 to test how effective the over-current protection really was. The Fluke registered the following max. values of the output current:
-- Protection set at 75 mA - current peaked at 326 mA (initially, and then went down to the set value),
-- Protection set at 204 mA - current peaked 1083 mA,
-- Protection set at 752 mA - current peaked 1641 mA.
CONCLUSION
I would suggest the following improvements in design: 1) move the pushbuttons to the outside; away from the knobs - it will make it little easier to operate both at the same time, 2) move the knobs a little further apart - it will create more room for large fingers, 3) make one click on the control knob increase/decrease the voltage or current by smaller value, preferably 0.01Volt and 1 mA per click, and the increase should grow with acceleration of turn (like in Boston clock radios); otherwise it would take forever to change a couple of Volts, 4) over-current protection needs to be perfected; if the spikes of current come from an output capacitor, then it needs to be placed before the limit control circuit.
The design of Extech 382260 is very much on the right track, but the resolution and over-current protection need to be reingeneered. I have a heavy 40-year-old HP power supply with two pots for coarse and fine adjustments that allow much more precise output resolution.
I really wanted to like this power supply. I especially liked the idea of using rotary switch to control the output voltage. I liked the 4-digit displays, the three ranges of voltage/current, and the universal AC supply voltage and how lightweight it is. However, for my needs (hobby electronics) the lack of precise voltage resolution control and major spikes of over-current were unacceptable.

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* Lightweight for easy portability * Complete with AC Power cord

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