New and used electronic test equipment can be expensive, but it is important for an engineer to have some minimum capability to power and test a device. Bench-top test equipment will top the list in terms of cost, so before you make a big purchase, consider carefully how much you need to spend on capabilities. If you have a specific plan for your equipment, you can avoid overpaying for equipment that you’ll never use.
Don’t Make These Five Purchasing Mistakes
#1: Focusing Only on Price
Price should not be the only factor that receives focus when selecting a new scope or meter. Some brands demand higher prices because their measurement units are known to be more durable, have greater capabilities, and offer additional options like upgrades and vendor resources. Sometimes, you just need a unit for a specific measurement and there is no need to go overboard on price.
Instead of focusing on price, focus on the capabilities you need, and think about these ahead of time. Even if the brand is lower-end, it is worth considering for your specific situation if the unit has the capabilities you need for your measurements. If price is still a factor, and you want a higher-end brand, you might consider a used piece of equipment.
#2: Not Looking Closely at Used Devices
Another aspect of price regards whether to buy new or used equipment. Just because a device is used or out-of-production doesn’t mean it’s not worth buying. There are many older oscilloscopes, DMMs, power supplies, and much more that remain highly competitive with the newest and most expensive equipment on the market.
Some old equipment could be in quite bad shape and at the end of its life, so it’s only good for parts. Other older equipment has been well-kept and even refurbished during its operating lifetime. If you are considering a used test unit, make sure you can answer the following questions:
- When was the device last calibrated, and can you verify the device is calibrated?
- If the device needs calibration, do you have the skills and tools to do the job?
- Does the vendor still offer support for the used equipment?
- Are other essentials for these devices available, such as probes or cables?
- Is available software compatible with a newer OS?
- Is documentation on the device still available online?
- Are spare parts available and are you confident you can repair the system if needed?
Sometimes, buying an older unit gives you less expensive access to great measurement capabilities, but the above points can add time and cost that make the undertaking less profitable. Another factor is the user interface and controls; newer units have much better options for displaying data and controlling key functions. Sometimes, given these factors, it’s better to just buy a new unit, even if you have to compromise on specifications.
This older Tektronix oscilloscope provides comparable capabilities to today’s models, but they are large and have old displays.
#3: Passing Over Older Interfaces
Take a look at an older oscilloscope, function generator, DMM, or power supply, and turn around the device to look at the back panel. One of the important features of these systems is the interfaces available to connect with other devices. There are several interfaces available on older devices, and some have still managed to make their way into newer devices:
- Serial or parallel ports (with D-sub connectors)
- GPIB connector
- Flying lead interface (could be serial, parallel, or both)
- Coaxial interfaces
- USB connection
- VGA or HDMI output
These interfaces greatly expand your capabilities and integration opportunities. For example, a simple VGA or HDMI output allows the device to broadcast to a monitor, or GPIB allows you to network your measurement devices into a single USB data stream for use in a measurement application.
GPIB is still an important interface on electronic test equipment.
#4: Sticking to USB Devices
Most of the newest systems on the market are now using a USB connection to provide data directly to a computer. Some of these will interface with a tablet or even your smartphone, and the data can then be viewed with an app. If you’re developing a custom app, or you’re using something like LabVIEW, you could capture data from multiple USB devices as well as issue commands to your USB devices.
Finally, some devices might not have any vendor software! You will be forced to develop your own application, typically in C/C++ or Python. There are also applications like LabVIEW that provide support for these devices. Open-source support or vendor support can vary greatly, so make sure you’re aware of the software solutions that might be available for your test equipment.
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