This module is a breakout board for an 801S vibration/shock sensor. The sensor contains a spring attached to one side of the cylindrical housing which makes or breaks contact with the housing (Basically a switch) and generates a square wave output when introduced to vibration or shock. This particular sensor is Normally Closed when no vibration is present. The sensor output is buffered by a comparator circuit and your final output is a square wave which is low (Pulled low by the comparator) when the sensor is still, and pulsing high when some kind of vibration or shock is present. The LM393 comparator has an open collector output, and the high voltage is produced from a pullup through the LED, which means your output voltage will be your supply voltage minus the LED drop (~2.0V). The pulses have no specified length but are more frequent (To the point where the output remains high) with enough vibration.
The potentiometer should allow the user to adjust how much vibration triggers an output pulse, but after some investigation we have found that it serves little to no purpose on these specific modules based on the circuit design. The potentiometer adjusts the voltage at the inverting input of the LM393 comparator, but the sensors output pulses are always at the same level as the supply, meaning the output from the comparator will always be an inverted replica of the output from the sensor. To adjust the sensitivity, you can add an RC filter at the output of the module and use different values to change the sensitivity.
Features / Specs
- Main Components: 801S Vibration Sensor and LM393 Comparator
- Operating Voltage: 3 – 9VDC
- Directionality: Omnidirectional
- Operation: Output is low (LED on) with no vibration, and pulses high (LED off) with vibration
- Indication LEDs: Single Output Indicator LED
- Dimensions: ~(10mm x 45mm x 15mm)