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.
When I received the power supply, I started with an unboxing, a quick inspection and some basic tests.
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.
The instrument has the following dimensions:
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:
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.
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.
After the initial tests, I continued the RoadTest with a series of experiments designed to compare my selection of 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:
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:
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) | |
| rms | p-p | |
| Aim-TTI QPX750SP | 1.55 - 2.29 | 18.0 - 23.0 |
| RD Tech DPH5005 | 3.70 - 21.14 | 92.9 - 214.5 |
| ATX | 3.33 - 18.69 | 81.9 - 166.1 |
| LTE 12V | 22.55 - 43.54 | 591.7 - 982.0 |
| Mean Well 12V | 4.44 - 12.66 | 176.4 - 178.3 |
| Mean Well /NXP 12V | 21.02 - 31.01 | 331.0 - 472.6 |
| IBM 16V | 18.73 - 63.49 | 248.27 - 590.51 |
| ASUS 19V | 20.48 - 27.24 | 320.6 - 373.7 |
| LiteON 19V | 25.79 - 35.59 | 316.7 - 327.8 |
| LiPo Battery | 1.31 - 1.44 | 25.43 - 33.58 |
| Arduino | 4.02 - 5.77 | 91.1 - 98.0 |
As you can see the Aim-TTI QPX750SP did better than all other supplies, except the LiPo battery.
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.
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:
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. 
) given the 750W power and features / connectivity of the instrument.
Hope you enjoyed this RoadTest!
