vibration sensor circuit schematic

Vibration Sensor / Detector Circuit

With the help of a simple ceramic piezo-electric detector it is possible to assemble an interesting and useful Impact sensor unit,which can be used to detect impact and vibration on doors, showcases, windows etc. The shock sensor (Ceramic piezo-electric detector) uses a “unimorph” diaphram, which consists of a piezo-electric ceramic disk laminated to a metal disk. The sensor supplies a voltage proportional to the acceleration of the impact or vibration, for example 40mV/G ie output is near 2V for 60G impact.

Here a low voltage, low current Impact sensor unit is realised using a standard ceramic piezo-electric detector which drives a monostable multivibrator (IC1) circuit to activate a npn silicon transistor (T1). Open collector output of this transistor switch can be interfaced to an external alarm/switch circuit for further processing. Since current consumption of the circuit is very low (from 5 to 6 mA only) any common 3V button cell can be used to power the sensor unit.When an impact is sensed, the monostable drives the transistor switch to ON , for a finite duration determined by the incircuit values of RC timing components R3 and C2.

Vibration/Impact Sensor Circuit Schematic

vibration sensor circuit schematic

The M74HC123 (IC1) is an high speed DUAL retriggerable CMOS MONOSTABLE MULTIVIBRATOR (MMV) fabricated with silicon gate C2MOS technology, with all inputs protected against static discharge and transient excess voltage. There are two trigger inputs, negative edge and positive edge. Here, only one monostable part with positive edge triggering (pin 2) is used. After triggering, the output maintains the monostable state for the time period determined by the external resistor R3 and capacitor C2.


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  • Jim Keith

    One important detail that was not mentioned is that the 74HC123 clock input features schmitt triggers that support slow pulse transition times. Monostable multivibrators without this feature will not work.

    • T.K.Hareendran

      Jim Keith:

      Yes, the B input (Schmitt-trigger input) is designed to handle pulses with a transition rate as slow as 0.1 mV/ns, with jitter-free one-shot action. This capability allows the IC to be used as an interface element between circuits with very slow-rising output pulses and circuits that require fast-rising input pulses. During prototyping, I looked up this application guide –

      Thank You!

  • gevageuligmail-com

    I would love to have some details about the components you used in this circuit as i am planning to use this design for my private project

    Kind regrads

  • Mayank panchal

    I m interested to this project or system. So plz send me all the information about it. Its my request.

  • shankar

    Sir, is it possible to sense vibrations of range 1-10hz using this circuit?

  • iglybigly

    vengene bengen vanom. Igly bigly baboon!
    iki iki aga wagha capoot?

  • kjnevin

    A junior tech here, I have a question about the circuit:

    I have to design a gate for a canoe slalom, this circuit is perfect for what I want to use to detect contact in the gate, expect for the I need to make the circuit produce an alert, ie a siren or a light needs to go on, how could I continue the circuit to produce this?

  • thana

    hi sir, i am a electronic engineering student in my country and im doing a project that named “earth quake detector”. by vibration can i use this circuit diagram for that project and if can please send the details and datasheet of this circuits. please sir, i need it urgently………..thank you.

    • Jim Keith

      Check out this vibration sensor:

      Sold by DigiKey, MSP6914-ND, $4.19 each

      This circuit probably will not trigger except with very large signals.

      To obtain reasonable sensitivity, you will need to amplify the signal by a factor of 100 or 1000 with a FET input op amp. Then you may be able to sense vibration from footsteps etc.

  • raj ...naem to suna hi hoga.....

    teri bahan chod dunga mukesh lund..

  • raj ...naem to suna hi hoga.....

    ma chudao kuutto….tum logo ki ma chandni chawk per chudegi…my name is raj.mukesh teri ma ka bhosda

  • Wilhelm

    Why don’t you delete idiot comments from apparent juveniles and just keep pertinent comments?
    Some come here for assistance not to read posts from grade school children.

    Thanks to the serious posters for your help.

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