Five-Way LCD Panel Meter Kit

This simple and cheap device has many uses, but it’s mainly intended to replace multiple panel meters. It can also be used as a small additional text screen for PC, Raspberry Pi or any other computer with USB. Whilst working on the high-current linear power supply design it became clear that we needed a way to show several different voltage and current readings, along with heatsink temperature, and it just didn’t make sense to use several panel meters for that job. It’s difficult enough to cut a single neat rectangle in the front panel of the instrument case to fit one screen, let alone three or even five. And there would be a lot of extra wiring if we used separate panel meters, plus increased current draw and it could end up pretty expensive.

This one low-cost device using a micro, an LCD screen and not much else makes the whole thing so much easier. There are two ways to use this board. In the Bench Supply, we’re feeding in five analog voltages with a common ground. These voltages are a fraction of the actual measured voltages (ie, the outputs of voltage dividers). The onboard micro samples these voltages and converts the values back to the original scales, then displays on them on the screen.

In the case of the fifth input, which is used for temperature sensing via an NTC thermistor, it also performs the required calculations to deal with the non-linear behaviour of the NTC. In the other mode, the micro detects when it is plugged into a USB interface and then behaves differently. You send it text over a virtual serial link, which is shown on the display. So you can easily show whatever you want on the 16x2 or larger 20x4 character backlit LCD screen.

Important Note For Kit Buyers:
This product is supplied in component form and requires soldering, drilling, and assembly. We recommend users are familiar with at least basic electronic principles and have the ability to solder.