A few months ago, I started to be on the lookout for some better test equipment – an oscilloscope, multimeter, electronic load, and power supply. These would allow me to create a few projects that I’ve been thinking of doing for a while and didn’t have the right tools to get started. I had grown tired of borrowing equipment from various places and wanted a set for myself that I could use whenever I want.
Before we move on, a huge thanks to Electro-Meters for helping out with the equipment upgrade! I reached out to Electro-Meters, the local distributor for Rigol equipment, and they were willing to provide a discount in exchange for mention on these project logs and images of the products being used in my projects over the next little bit. They were great to deal with during the whole process! Check out their selection of equipment here.
What equipment to buy:
I do quite a bit of work with batteries, so having a power supply and electronic load to charge and discharge the batteries is a must. These are also super helpful for testing power distribution circuits and DC-DC converters. A multi-channel power supply (or 2 power supplies) was a requirement as I often find myself wanting to charge a battery and do something else at the same time.
A good DMM was also on the list as I need one that I can trust. I was getting tired of using the cheap handheld ones and trying to guess at what the voltage or current actually is. A few reasons for the upgrade from handheld to bench meters are below:
- For batteries, even a few tens of millivolts difference can make the difference between them being fine to connect in parallel or if they need to be balanced first.
- Keep other instruments in calibration. A 5.5 digit meter would have been good enough for typical battery or hardware debugging, but a 6.5 digit is even better for keeping power supplies in calibration.
- Fast measurement speed – when you’re testing voltage on 100 batteries, the fast measurement speed (Ability to change the NPLC count) of a bench meter makes everything a lot faster.
- Automating testing with a Python over SCPI. This enables automatic testing such as generating the efficiency curve of a DC-DC converter under different loads through a single python script. Remote sense inputs on the PSU/e-Load or extra DMMs are required to eliminate cable loss from the measurement.
Last but not least, an entry-level 4-channel oscilloscope can help debug the majority of bugs that may be encountered during bringup of a new board.
What brand to go with:
I wanted to go for some reliable equipment that wouldn’t break the bank but would also last a while and be fairly capable entry-level equipment.
I didn’t have much confidence in any of the cheap Aliexpress-style brands as I had seen way too many teardowns of them and don’t trust the quality. While it is often stuff that can be fixed pretty easily (noisy fans, cables too small, not enough mains isolation), I didn’t want to have to deal with it and wanted this equipment to be a tool and not a project.
Here in North America, Keysight equipment is generally regarded as some of the best test equipment, but it gets pretty expensive. A 6.5 digit multimeter would set you back about $1500.
I’ve used several BK Precision electronic loads and switching power supplies in the past, and have no complaints about them. They are solid pieces of hardware, and work great, but still a bit too expensive for me.
Rigol and Siglent are generally regarded as entry level test equipment, and they make a great product for the price, but on my student budget it was still a bit expensive.
The other reason I was swayed towards Rigol equipment was the reports of it being easily hackable through the activation codes to unlock extra accuracy and bandwidth capabilities. A few guides linked for the Oscilloscope here and the e-Load and power supply here. As most of the guides online mention, it was pretty straightforward to make these upgrades.
I purchased the following equipment at a discount from Electro-Meters:
- Rigol DS1054Z 4-channel Oscilloscope (Upgraded with protocol decoding and 100MHz bandwidth)
- Rigol DL3021 Electronic Load(Upgraded to DL3021A)
- Rigol DP832 3-channel Power Supply (Upgraded to DP832A). Remote sense is not available on this model, but having the DMM handy makes accurate measurements easy.
- Rigol DM3068 6.5-digit Multimeter
After upgrading the Electronic load and power supply, the characteristic color screens (as opposed to the single color displays on the non-A versions) were shown after a reboot. When you consider the added accuracy, they are a pretty good deal.
I’ve been spending some time setting up the SCPI commands to interface with these a get a full battery cycle test going, and will make a post for that soon.