Simulator showing sensor circuit on. Meter or Guage Needle ( shown as line with ammeter) on weight scale or other measure device turns on sensor in tube housing, (shown as parallel SPST switches) mounted on dial glass which keeps sensor focused for needle movement at tube opening and can shut- off relay to material feed-in to insure accurate measurements for concrete or other mixing systems to have uniform quality control.
PIR Module (Passive Infrared Sensor) operates on 12 to 24 volts. I glanced at LPIR-6A has 4 connections, two for power supply and two for switching circuit.
Other analog meter dial movements could also be used to trigger electrical circuits.
