#TwoMinuteTeardown: Panel Mount Liquid Level Indicator
Generic liquid level meter teardown
I ordered this part years ago for a project I eventually canceled.
I can’t use it for anything, and it’s just taking up space, so I’m going to open it up before I recycle it.
The Ali Express listing is a 404 so I don’t have a link to share or really any information about it.
The main thing to take away is that it’s meant to interface with a liquid level sensor. It will display the level of liquid in a tank and - optionally - trigger a few relays based on the level.
This is a generic case; not all screw terminals pictured here are actually wired up to anything on this model.
Not all the screw terminals are actually wired up to anything on this model; the case is generic.
The main body slides off pretty easily. There are two PCBs inside: one for the display and one to handle the relays and sensor input.
The display PCB is pretty simple; no active electronics and a tonne of LEDs. The bar graph LEDs are almost certainly charlieplexed but the 7 segment might have an integrated driver.
The screw terminals on the rear of the case are directly soldered to the main PCB so I’m not going to be able to take it apart any further without disordering things… defeating the spirit of the #TwoMinuteTeardown.
Looking at the top left, you can see the few pins for the 7-segment displays; a total of 12 pins. Of those 12, some don’t have traces leading to them so they’re probably just for mechanical support. There are far too few remaining pins for even basic charlieplexing so I’m guessing there’s an integrated driver of some kind. Probably a max7219 or similar
The main ICs
Really just the one main application processor and a few support ICs.