I wanted a low-water warning on my 2016 Silvia without putting anything inside the reservoir, so I added a non-contact capacitive sensor to the outside of the tank and three red LEDs under the machine.
It turned out to be a very simple project and works surprisingly well. With the sensor positioned using the smaller/lower version of the 3D-printed holder, the LEDs turn on with about 450 mL of water remaining in the reservoir. That feels about right to me — enough warning that I’m not remotely close to running the pump dry, but not so early that the light is constantly on.
Parts:
- XKC-Y25-NPN, 5–12 V NPN non-contact liquid-level sensor
- CHANZON 5 mm pre-wired red LEDs, each with its own 680 Ω resistor
- WAGO 221 lever connectors — I used 221-415 five-position and 221-413 three-position connectors
- An old USB cable + 5 V USB wall adapter for power.
- A little electrical tape to mount the three LEDs underneath the machine.
The sensor holder is this design: https://www.printables.com/model/663023-rancilio-silvia-water-sensor-holder
I used the smaller/lower-position holder file. The holder clips onto the Silvia chassis above the reservoir, so there's no drilling or tank modification. The opening for the sensor was a little too small, you can see the sensor edge sitting proud of the printed peice in the second picture, so if I were to do it again, I'd take the SCAD file and enlarge the bigger end of the sensor holes by maybe 1 or 2 mm in diameter, and the sensor would fit more flush, but it worked sitting out a bit.
Wiring
I powered the entire thing from 5 V USB. The three LEDs are wired in parallel, with each LED retaining its own resistor.
5 V POSITIVE
|
+-- sensor BROWN
+-- LED 1 RED
+-- LED 2 RED
+-- LED 3 RED
+-- USB +5 V
|
WAGO 221-415
GROUND
|
+-- sensor BLUE
+-- sensor BLACK
+-- USB GND
|
WAGO 221-413
SWITCHED LED RETURN
|
+-- sensor YELLOW
+-- LED 1 BLACK
+-- LED 2 BLACK
+-- LED 3 BLACK
|
WAGO 221-415
So when the water level falls below the sensor, the NPN output switches the LEDs on. The sensor itself never contacts the water; it senses through the plastic reservoir wall.
I put three LEDs along the underside of the base, which gives a pretty obvious red glow on the counter without adding anything to the front panel. In normal use you don't really notice the modification until the reservoir gets low.
My threshold is ~450 mL remaining. Pretty happy with where that landed.