The AIM-TTI QPX750SP is a powerful bench power supply, capable of providing a maximum of 750W DC power within a wide voltage range of 0-80 V. It is a professional instrument I got for testing as part of the AIM-TTI Bench Power Supply RoadTest.

Aim-TTi QPX750SP Bench /System DC Power supply

This blog post is the 1st one from a series of blog posts, in which I will try to thoroughly evaluate the unit.

 

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

 

1. Motivation

 

A good bench power supply is an essential tool of an electronic hobbyist.

Most hobbyist (including me ) however do not pay too much attention on what (bench) power supply they are using.

 

For example, I usually choose one of the bellow "power supplies" depending on the needs:

  • RD Tech DPH5005, a relatively cheap 50V / 5A current limited DC-DC buck-boost power supply
  • old ATX power supply converted to bench supply, providing 12V, 5V and 3.3V DC
  • various 12V DC adapters
  • various power adapters for laptops, usually 16-19V DC
  • 3.3V and 5V generated with a random Arduino board
  • LiPo batteries connected in different configurations

 

Now, the above "power supplies" are either low-end bench power supplies, or not suited for testing / development purposes at all. The reason I still use them is that probably I do no really understand (yet) the limitation of the above supplies, and the benefits of a decent bench power supply.

 

The AIM-TTI QPX750SP Bench Power Supply will be an ideal replacement for my collection of low-end power supplies. The QPX750SP has way better specs than all of the above "power supplies". Additionally, it has some features like LAN (LXI) and GPIB interfaces, which allow some interesting application featuring remote monitoring / control.

 

My goal for this Road Test is to gain general knowledge about power supplies, and also help other hobbyists to do so.

 

The plan for this road test is to do a practical comparison between the AIM-TTI QPX750SP Bench Power Supply and my collection of dubious "power supplies".

 

2. Power Supplies

 

As I mentioned earlier, the AIM-TTI QPX750SP will be tested against my collection of "bench" power supplies, I usually use to supply power to my projects.

 

So, here is the list of power supplies I will evaluate in this road test:

 

Power SupplyDescription

AIM-TTI QPX750SP

Single output lab DC power supply with a maximum power output of 750W.

 

Voltage: 0 - 80 V

Current: 0 - 50 A

Power: 0 - 750 W

 

Operating Modes:
constant voltage (CV), constant current (CC), constant power (CP)

 

Features:

over voltage protection (OVP), over current protection (OVC)

LAN and USB connectivity

(product page)

RD Tech DPH5005

Lab supply / DC-DC buck-boost converter with a DC input.

 

Voltage: 0 - 50 V

Current: 0 - 5 A

Power: 0 - 250 W

 

Operating Modes:
constant voltage (CV), constant current (CC)

 

Features:

optional USB / Bluetooth connectivity

 

(product page)

Modified ATX Power Supply
(Premier LC-8460BTX)

ATX power supply modified to be used as a primitive lab supply.

 

Voltage: 3.3, 5, 12V, -12V

Current: 22 / 15 / 16 A (max)

 

Specs:

IBM Laptop Charger / Supply
(16V)

 

Voltage: 16 V

Current: 3.36 A (max)

Power: ~ 54 W (max)

ASUS Laptop Charger / Supply

(19V)

 

Voltage: 19 V

Current: 3.42 A (max)

Power: ~ 60 W (max)

Mean Well Power Adapter

(12V)

Voltage: 12 V

Current: 2.5 A (max)

Power: ~ 30 W (max)

LiteOn Power Brick

(19V, designed for NVIDIA)

The power supply of a Jetson AGX Xavier development kit.

 

Voltage: 19 V

Current: 3.42 A (max)

Power: ~ 60 W (max)

LTE Power Brick

(12V, designed for Xilinx?)

The power supply of a Xilinx ZCU104 evaluation kit.

 

Voltage: 12 V

Current: 5 A (max)

Power: ~ 60 W (max)

Arduino Like Boards

Commonly used to provide 3.3 V and 5 V for testing.

 

Voltage: 3.3 / 5 V

Current: ~ 1 / 1.5 / 2 A (max)

LiPo Battery

(Turnigy Bolt 1800)

High performance LiPo battery with 4 cells and a 1800 mAh capacity.

 

Voltage: 15.2 V (17.6 V fully charged)

Current: 65 - 130 C (~117 A continuous / 234 A peak)

 

 

3. Dummy Loads

 

As you may have already guessed, I don't have a programmable electronic load to properly test these power supplies.

 

Instead, we will use a set of DIY loads to simulate different kind of devices that could be powered with a power supply:

 

LoadDescription

Heating Element salvaged from broken Steam Iron

Resistive load.

 

Resistance: 36 Ω

Power: ~1500W @ 230V

Heating Element salvaged from broken Cooking Panel

Resistive load.

 

Resistance: 41 Ω

Power: ~1300W @ 230V

Heating Element salvaged from broken Bread Machine

Resistive load.

 

 

Resistance: 93 Ω

Power: ~570W @ 230V

Floor Heating Film, 12V

Resistive load.

 

 

 

Resistance: 4.2 Ω

Power: ~35W @ 12V

DC Motor salvaged from broken Bread Machine

Inductive load.

 

DC motor with 50W power.

 

Inductance: ?

Power: 50W @ 230V

 

Will be used with a fly-back diode for protection.

Electrolytic Capacitors

Relatively high value capacitors (100uF / 35V).

 

Capacitance: 100uF x 20

 

The capacitors will be packed in a bank, and will be
used to the check the power supplies response to capacitive loads.

DIY DC Electronic Load

I will also try to build a simple DC Electronic Load.

 

It will consists of a MOSFET controlled by a micro-controller, a restive load and some filter caps.

 

4. Test Equipment

 

To examine the power supplies behavior under different conditions the following test equipment will be used:

 

Test EquipmentDescription

Keysight MSOX3034TMSOX3034T Mixed Signal Oscilloscope

The MSOX3034TMSOX3034T is a four channel, 350MHz bandwidth mixed signal oscilloscope I reviewed last year:

InfiniiVision 3000T X-Series Oscilloscope MSOX3034 - Review

 

It will be used to monitor the voltage and current response of the tested power supplies.

Hantek CC-65 Current Probe

Hantek CC 65 Ac/Dc Current Clamp Meter Multimeter With BNC Connector From  Factory Directly Free Shipping|multimeter digital|multimeter  symbolsmultimeter manufacturers - AliExpress

Oscilloscope probe for non-contact current measurement.

Vici VC99 Handheld Digital Multimeter

VICI VC99 3 6/7 Auto Range Digital Multimeter DC AC Voltage Current  Resistance Capacitance Meter Alligator Probe 100% Original|vici vc99|vc99 3  6/7multimeter dc ac - AliExpress

Handheld multimeter capable of measuring both voltage and current.

Keysight U1231AU1231A Handheld Digital Multimeter

 

Keysight Agilent U1231A True RMS 6000 Count | Transcat

Handheld multimeter capable of measuring voltage.

PC / Raspberry Pi / Arduino

PI4 4GB BULK | Raspberry Pi 4 1.5GHz Quad-Core, 4GB RAM | Distrelec România

For data logging and control purposes.

 

5. Test Plan

 

The Road Test review will consists in multiple blog posts and the final road test review.

 

The Road Test will focus on different aspects of the power supplies, and they will also include experiments targeting:

  • operating modes - constant voltage, constant current, constant power
  • output ripple and noise
  • settings resolution - voltage, current
  • protections - over voltage, over current, short circuit
  • load handling characteristics - resistive / inductive / capacitive loads, dynamic load
  • etc.

 

The next blog post will focus on behaviour of the tested the power supplies under static loads (resistive / inductive / capacitive). Then, the following blog posts will focus on aspects like dynamic load handling, protections, and others.

 

In the final Road Test Review I will do a recap comparison between the tested power supplies, and I will also take a look on the different features of the AIM-TTI QPX750SP.

 

Stay tuned!