AIM-TTI Bench Power Supply - Review

Table of contents

RoadTest: AIM-TTI Bench Power Supply

Author: Attila Tőkés

Creation date:

Evaluation Type: Power Supplies

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: Compared it to the RD Tech DPH5005 (although is not really the same category).

What were the biggest problems encountered?: There was nothing significant.

Detailed Review:


Previous blog posts of this RoadTest:

AIM-TTI QPX750SP RoadTest | A Non-Conventional Power Supply Review

AIM-TTI QPX750SP RoadTest | Passive Load Experiments

AIM-TTI QPX750SP RoadTest | Dynamic Load Behavior & Protections

AIM-TTI QPX750SP RoadTest | Miscellaneous Features

 

Hi Element14 Community!

 

This is the final part of my RoadTest review of the Aim-TTi QPX750SP lab power supply:

With this occasion, I would like to thank Aim-TTi and Element14 again for providing this power supply. I'm confident it will be very useful for many of my future projects.

 

My proposal for this RoadTest was to compare the Aim-TTi QPX750SP against a series of devices I and other hobbyists are using as power supplies for DIY projects.

 

1. First Impressions

 

When I received the power supply, I started with an unboxing, a quick inspection and some basic tests.

 

1.1 Packaging & Accessories

 

The power supply arrived in a bit over-sized card box. The instrument was secured with a foam structure:

In terms of accessories we got 3 x power cords (EU, UK, US), a Safety Instructions sheet and some other documentation. These were kind of "floating" in the empty space from the box:

An  Instruction Manual was not included, but it can be downloaded from AimTTi's website.

 

1.2 Form Factor

 

The instrument has the following dimensions:

  • Width: 21.5 cm
  • Height: 12.8 cm / + 1.5 cm with standoffs
  • Depth: 38 cm  /  + 2 x 4.2 mm with front & back connectors

 

The depth of the instrument was a bit of a surprise for me, as the stock photos does not really show how deep the power supply actually is:

aim-tti bench power supply

This form factor is a bit inconvenient for bench-top use, as it will likely occupy a significant part from the depth of the table. This seems to be a compromise to allow rack mounting two units side by side in a 4U space.

 

The instrument has stand-offs in front, allowing to tilt the instrument upwards a couple degrees. This is great feature which improves visibility of the screen.

 

1.3 Power Up & Noise

After reading the Safety and Installation sections of the Instruction Manual, I proceeded to power up the instrument.

 

The power switch seems to be software one, as the cooling fan spins up for a couple of seconds as soon the power cord is connected to the mains. Otherwise, in idle and low power operation, the noise produced by the cooling fan is reasonable low, except some unnecessary spin-ups when the device is powered ON or OFF.

 

The instrument comes with a touch screen, but also with physical controls. The user interface is fairly intuitive, I was able to use it without reading the manual.

 

The instrument came with the latest firmware available on the website, which is definitely a good point.

 

2. Experiments

 

After the initial tests, I continued the RoadTest with a series of experiments designed to compare my selection of power supplies.

 

2.1 Power Supplies

 

The power supplies used for the experiments were different devices, ranging from a cheap "bench" power supply, a modified ATX power supply:

power bricks:

to Arduino style boards:

and a LiPo battery:

 

2.2 Dummy Loads

 

As I don't had a programmable electronic load to properly test the power supplies, I used some DIY loads made from components salvaged from broken electric devices.

 

These included a series of resistive elements:

a DC motor:

and some capacitors:

 

2.3 Passive Load Experiments

 

The first set of experiments was focused on passive loads:

These included tests with resistive, inductive and capacitive loads. The different power supplies were tested against loads at different voltages.


    (example combinations for resistive loads)

For each of the tests I measured the ripple and noise (rms and peak-to-peak). I also checked the the behaviour on turn on and off events.

 

Here is a (very) brief comparison based on the test results:

Power Supply

Output Ripple + Noise (mV)

(over different voltage ranges)

rmsp-p
Aim-TTI QPX750SP1.55 - 2.2918.0 - 23.0
RD Tech DPH50053.70 - 21.1492.9 - 214.5
ATX3.33 - 18.6981.9 - 166.1
LTE 12V22.55 - 43.54591.7 - 982.0
Mean Well 12V4.44 - 12.66176.4 - 178.3
Mean Well /NXP 12V21.02 - 31.01331.0 - 472.6
IBM 16V18.73 - 63.49248.27 - 590.51
ASUS 19V20.48 - 27.24320.6 - 373.7
LiteON 19V25.79 - 35.59316.7 - 327.8
LiPo Battery1.31 - 1.4425.43 - 33.58
Arduino4.02 - 5.7791.1 - 98.0

 

As you can see the Aim-TTI QPX750SP did better than all other supplies, except the LiPo battery.

 

2.4 Dynamic Load Behavior & Protections

 

Next, I continued with some experiments with a more dynamic nature.

 

For these test I kept only the two "bench" style power supplies: the Aim-TTI QPX750SP and the RD Tech DPH5005.

 

I checked the power supplies behaviour under changing loads, in current limiting mode and facing short circuits.

 

The test setup looked like this:

As the experiments involved dynamic behaviour, I focused on measuring the time taken to react / stabilize after each event.

 

Here is a brief summary of the results:

 

Power Supply

Time to Stabilize (ms)
Load Change
36Ω ⇒ 3.75Ω
Load Change
3.75Ω ⇒ 36Ω
Current Limiting
OFF ⇒ ON
Current Limiting
ON ⇒ OFF
Short Circuit
36Ω ⇒ 0Ω
Aim-TTI QPX750SP~ 3 ms

-570mV
undershot
~ 2.5 ms

+480mV
overshot
~ 28.75 ms

-2.02V
undershot
~ 10.05 ms

+1.44V
overshot
0.720 ms
RD Tech DPH5005~ 1.5 ms

-570mV
undershot
~ 0.25 ms

+390mV
overshot
~ 8.58 ms

no
undershot
~ 1.9 ms

+160mV
overshot
0.250 ms

 

Surprisingly, it the scenarios I tested, the RD Tech DPH5005 had better reaction time and fewer / smaller artifacts (under / overshot), compared to the Aim-TTI QPX750SP.

 

2.5 A Programmatically Controlled Experiment

 

In my last blog post, I wanted to try out the control over LAN / Ethernet feature of the Aim-TTI QPX750SP.

 

For this I connected the instrument to my home network using a LAN cable. The instrument picked and IP address automatically, and exposed a web interface over the local network.

 

Next, I prepared a programmatically controlled experiment in a Jupyter Notebook, using the PyVISA Python library:

 

The experiments sweeps over a range of voltages, and retrieves the voltage and current readings from the QPX750SP:

 

The collected data are then displayed in a graph:

 

3. Conclusions

 

The Aim-TTI QPX750SP is pretty good power supply for medium / high power applications. Overall, I was satisfied with the instruments performance, user interface and connectivity.

 

3.1 What I liked?

 

  • The user interface, both touch screen and traditional, is intuitive and easy to use.

  • The instrument offers high power (750W) over a wide voltage range. Good for high current applications.

  • The remote control capability over LAN / Ethernet.

 

  • The price (~1250 EUR) seems to be decent (maybe not for hobby use ) given the 750W power and features / connectivity of the instrument.

 

3.2 What I didn't liked?

 

  • The form factor is not ideal for bench top use.

 

  • The cooling fan has unnecessary spin-ups when the device is turned on or off.

  • Response to dynamic event (load change, current limiting) could be faster (or at least configurable)

 

  • Packaging could be done better.

 

Hope you enjoyed this RoadTest!

Anonymous