To add to my slowly growing lab capabilities, last month I acquired a Fluke 8840A 5.5 digit multimeter and a FeelElec FY6800 60MHz digital signal generator / counter. The Fluke is a second-hand device I found on eBay, and although it looks like it’s been well used it’s in good working order and still in calibration. I’m primarily using it to make low-voltage measurements across shunt 0.1Ω or 1Ω resistors to determine power consumption of battery-powered systems. With modern processors, it’s not unreasonable to expect average consumption in the low micro-amps if sleep modes are used correctly. In fact, quite often processors that might seem more power-hungry, such as low-end 32-bit ARM devices are cheaper and lower power than “classic” low-power devices such as 8-bit micros.
The Signal Generator is used to create test waveforms of particular frequencies, duty cycles or shapes to provide external stimulus, for example to simulate an encoder coming from a motor. Buying it was a bit of an experiment as it falls under the category of cheapy chinese equipment at around £99, but having watched some teardowns and reviews of the device online I am satisfied that it will do just as good a job as my go-to alternative, which is to program a dev board to produce stimulus waveforms. They’ve made some interesting, but not entirely bad design decisions in the device, not least creating a DAC from a huge resistor ladder driven by a high pin-count FPGA! As for long-term reliability, well my lab is not the most demanding of environments so I am sure it will last well enough. Except the Fluke, which I expect will out-live every other piece of equipment!