Mesh Sensor
In DevelopmentA solar-powered node for reading 4-20mA industrial sensors. Same enclosure design as DropLink, with an ADC circuit for analog sensor input.
This is not a product for sale. These are notes on a planned hardware design.
How It Works
Sensor Signal
4-20mA sensor outputs current proportional to measurement
ADC Conversion
Current-to-voltage circuit feeds microcontroller ADC
Mesh Transmit
Reading sent as telemetry packet over LoRa mesh
Dashboard
Gateway bridges to MQTT, values stored and displayed
Why 4-20mA?
4-20mA is an industrial standard for analog sensor signals. Current loops are noise-resistant and can run long cable lengths without signal degradation.
Noise Immunity
Current signals resist electrical noise better than voltage
Long Cable Runs
Can run hundreds of feet without signal loss
Fault Detection
4mA = zero, so 0mA indicates broken wire or sensor fault
Signal Range
Linear scale from 4mA (0%) to 20mA (100%)
Compatible Sensor Types
Any sensor with 4-20mA output should work. Common applications:
Water Level
Submersible pressure transducers
Temperature
RTD or thermocouple transmitters
Turbidity
Optical turbidity sensors
Pressure
Tank or pipe pressure sensors
Flow
Flow meters with 4-20mA output
pH
Water quality pH sensors
Planned Hardware
| Base | Same as DropLink (RAK4631 or Heltec V3) |
| ADC | ADS1115 or similar 16-bit I2C ADC |
| Current Sense | Precision resistor (250Ω for 1-5V output) |
| Power | Solar + 18650 (same as DropLink) |
| Enclosure | Weatherproof ABS with cable glands |
Design not finalized. Components may change.
Work in Progress
This design is still being developed. Check the dashboard for updates on deployed sensor nodes.