A vibration sensor circuit acts like a tiny touchy feely friend for electronics.
It can sense shaking or sudden movements and send an electrical signal when it does.
This makes it perfect for things like burglar alarms to feel someone breaking in, earthquake detectors to feel the ground shaking or even monitoring machines in factories to know if something is working properly.
Circuit Working:
Parts List:
| Type | Description | Quantity | Wattage/Specs |
|---|---|---|---|
| Resistors | 4.7M | 2 | 1/4 watt |
| 100k | 1 | 1/4 watt | |
| 10k | 1 | 1/4 watt | |
| Capacitors | Ceramic 100nF | 1 | |
| Electrolytic 47µF 16V | 1 | ||
| Semiconductors | IC 74HC123 | 1 | |
| Transistor BC547 | 1 | ||
| Diode 1N4007 | 1 | ||
| Others | Piezo sensor | 1 | |
| Relay 12V | 1 |
Utilizing a basic ceramic piezo electric detector one can construct a practical Impact sensor unit capable of detecting impacts and vibrations on doors, showcases, windows and similar surfaces.
This shock sensor utilizes a ‘unimorph’ diaphragm, which combines a piezo electric ceramic disk with a metal disk.
The sensor generates a voltage proportional to the acceleration of the impact or vibration typically around 40mV/G resulting in an output of approximately 2V for a 60G impact.
This setup features a low voltage, low current Impact sensor unit employing a standard ceramic piezo electric detector that drives a monostable multivibrator IC1 circuit to activate an NPN silicon transistor T1.
The open collector output of this transistor switch can be connected to an external alarm or switch circuit for further processing.
When an impact is detected the monostable triggers the transistor switch to turn ON for a specific duration determined by the in circuit values of the RC timing components R3 and C2.
The 74HC123 IC1 is a high speed DUAL retriggerable CMOS monostable multivibrator MMV manufactured with silicon gate C2MOS technology featuring inputs protected against static discharge and transient excess voltage.
This device includes two trigger inputs, negative edge, and positive edge, although in this application only one monostable part with positive edge triggering pin 2 is utilized.
Upon triggering, the output maintains the monostable state for the duration determined by the external resistor R3 and capacitor C2.
Formula:
For the 74HC123, the following estimated output pulse width (tW) computation is the most often used relationship:
tW = 1.1 * Rx * Cx
where,
- tW is output pulse width in seconds
- Rx external timing resistor in ohms
- Cx external timing capacitor in farads
Note:
The actual pulse width may differ depending on the listed criteria, this calculation is only an estimate.
How to Build:
To build a Simple Vibration Sensor Circuit follow the below mentioned circuit building steps:
Assemble the components:
- Gather all the components required for the sensor unit.
Connect the shock sensor:
- Connect the ceramic piezo electric detector shock sensor to the circuit.
- The exact wiring will depend on the specific sensor you are using so refer to the sensors datasheet for the correct connections.
Connect the monostable multivibrator IC IC1:
- Connect the monostable multivibrator IC 74HC123 to the circuit according to its datasheet.
- Ensure that the correct pins are connected to the other components in the circuit.
Connect the NPN silicon transistor T1:
- Connect the NPN silicon transistor BC547 to the circuit according to its datasheet.
- This transistor will be activated by the monostable multivibrator IC.
Add the resistors and capacitors:
- Connect the resistors R1, R2, R3 and R4 and capacitors C1 and C2 to the circuit according to the schematic.
- These components determine the timing and behavior of the monostable multivibrator.
Power the circuit:
- Connect the power source 12V to the circuit to power it.
- Ensure that the voltage is correct for all components used.
Test the circuit:
- Test the sensor unit by applying an impact or vibration to the ceramic piezo electric detector.
- The monostable multivibrator should trigger the NPN silicon transistor BC547 which can then be connected to an external alarm or switch circuit for further processing.
Adjustments:
- If necessary, adjust the values of the resistors and capacitors to change the sensitivity or timing of the sensor unit.
Optional:
- If you want to integrate the sensor unit with an external alarm or switch circuit connect the output of the transistor to the input of the external circuit.
Finalize the setup:
- Once you have tested and adjusted the sensor unit to your satisfaction, finalize the setup by securing all components and wiring in place.
Note:
- Please note that working with electronic circuits involves handling potentially hazardous components, such as batteries and soldering equipment.
- Ensure that you have the necessary skills and knowledge to work safely with these components.
Conclusion:
A vibration sensor circuit is a vital component in various applications where the detection of mechanical vibrations or sudden movements is crucial.
By converting physical vibrations into electrical signals, these circuits enable the monitoring and triggering of alarms or other actions enhancing safety and security in a variety of scenarios.