tilt sensor alarm

Tilt Sensor Alarm Circuit

Ultra simple circuit of the tilt sensor alarm presented here can be fabricated using readily available inexpensive components. The circuit is a true transistor based design. Home made Tilt sensor for this circuit is an ordinary little glass/plastic bottle with two metal needles inserted through its cap, and a small quantity of water inside.
You can also try your own ideas to make the tilt sensor. A 9V alkaline battery is enough for powering the whole circuit.

Tilt Sensor Circuit Schematic

tilt sensor alarm schematic

Usually, transistor T1 is in inactive state. When the sensor assembly is tilted, both needles inside the sensor (bottle) are short circuited by the water and a positive voltage is available at the base of T1 and it becomes active. Activation of T1 causes the activation of next transistors T2 and T3. After this, T2 supplies constant bias for T1 to make it latched and T3 triggers the SCR(T4) which inturn energises the active piezo-sounder(BZ1). Once activated the circuit can be deactivated by depressing the power/reset switch S1.

Preset pot P1 is deliberately added here to adjust the circuit sensitivity. This may become necessary if you are trying a different (readymade) tilt sensor. Similarly,SCR(T4) and piezosounder (BZ1) may be replaced with near equivalent parts. Resistor R3 (100-150 Ohm) is optional.


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  • Colin Mitchell

    “This is my final response to Colin’s comments because he deserves nothing, and time is valuable!”

    Why doesn’t T.K.HAREENDRAN answer my comments as to why he did not included current-limiting resistors in the circuit ????

    He just keeps sending me rude, inconsequential emails, without answering any of the points I have brought up about his faulty designs.

    It’s no wonder beginners get put-off with the internet, when inept people are allowed to present circuits that have never been tested and are not updated when shown to be faulty.

  • Mihai

    Oh my God not again!

  • T.K.Hareendran

    Now I think Colin Mitchel have some madness. Because I have no idea about the above posted email. Who sent it?

    Further, I haven’t a website till date. I wonder what he mention about. I think this is another trickery by him.

    This is my final response to Colin’s comments because he deserves nothing, and time is valuable!

  • Colin Mitchell

    Instead of answering my comments about the poor circuit design, T.K.HAREENDRAN sends me this stupid email:

    After doing some research I found that you are a big zero that knows nothing in advanced electronics. What you can do is wiring circuits using bc series transistors and old pics. The resulting irritation is the real fact behind your madness-driven criticism.

    You are a critic without any updated credentials to show before the public. You are just repeating your old stories.

    Your victims like dattatajvidyasagar,dmohnakumar, all are reputed indian geeks with years long experience in the domain. I am not a keralite but I maintain a good relationship with all of them since my iit days. tk sir maintains a well-established lab, dmohnakumar runs a good project centre,dattaraj sir just started a new academy. I salute such persons.

    But when turning to you, you are a mad guy needs adult supervision and medication. If I can I will throw you off from web to stop the ever-increasing polluting activities by you.TALKING ELECTRONICS: WHAT IS IN IT? NOTHING TO FOLLOW %%%FU

    You can see the dozens of faulty designs of all these “geeks” on my website.
    None of them know the basics of electronics and none of them have challenged any of my comments.
    Simply build any of the circuits designed by these “geeks” and you will see the faults.
    TK SIR had a terrible website until I exposed his lack of knowledge and his site was taken down. All the faulty circuits were removed !!!
    You can still see all his rubbish on my website.

    I have dozens of faulty circuits from T.K.HAREENDRAN.
    All I am doing is exposing ANYONE who produces the wrong information ON ANY SUBJECT.
    I have never had any comment from anyone to say my comments are incorrect.
    I have had 22million visitors to my website and T.K.HAREENDRAN is the only one that sends stupid emails without ever acknowledging his mistakes.
    I ask him to comment on why he has produced such a stupid circuit TILT SENSOR and why all his circuits have faults.

  • Colin Mitchell

    “I’ve been watching the polemic between you and T.K.HAREENDRAN and it seems it will never end. I think it’s time to put an end to this. Let him be.”
    An intelligent person would make corrections to the project so others don’t build something that does not work.
    You will notice he does not even rely to my corrections.
    I have pages and pages of his faulty designs and he keeps putting this stuff in Electronics For You Magazine, where the editor has absolutely no understanding of electronics and just publishes this rubbish.
    And an intelligent magazine would publish my corrections – but they hide behind not ever answering any of my emails.
    What more can I say.

  • Colin Mitchell

    T.K.HAREENDRAN obviously used a weak 9v battery to test the circuit and that’s why he thinks it will work.
    Try a 9v power supply or increase the voltage to12v and see SMOKE.
    T.K.HAREENDRAN keeps sending me rude emails under a different name but never explains where he got his bazaar education or why he keeps outputting such JUNK.
    I get hundreds of emails from around the world from readers who have said my website has taught them more than all the education from their university studies.
    These are not my emails. These are from readers and I include their email address.
    Show me anywhere where my comments are irrelevant or biased?
    I criticise ANYONE who delivers faulty circuits.
    I have 25 pages of faulty circuits and this is hundreds of circuits.
    Not one person has written to say any of my comments are incorrect.
    There is not one other person on the web that has produced such a library of faulty circuits and an analysis of how and why they are faulty.
    You can learn more from these pages than any text book.
    It is T.K.HAREENDRAN and authors like him that should be stopped from putting such junk on the web.
    His circuits are just giving electronics a bad name.
    Beginners will be hesitant to build anything when they find the circuits either do not work or just BLOW UP THE TRANSISTORS.

    • Mihai

      our comment is awaiting moderation.

      Right on!

      Either this guy doesn’t know how a SCR works or he doesn’t know what a latch is. That’s sad.

      On the other hand…

      I’ve been watching the polemic between you and T.K.HAREENDRAN and it seems it will never end. I think it’s time to put an end to this. Let him be. Don’t be too harsh on him. I think he’s got it.

  • Colin Mitchell

    “How do you analyze the SCR for this circuit???”

    Why do you want 90mA to energise the gate of the SCR?
    The 100 ohm resistor is far too low.
    What is the purpose of R3 ????
    The whole circuit is just JUNK,
    T.K.HAREENDRAN cannot design for nuts.
    Why have a latching circuit in the front-end when the SCR is a latch???

  • Kevin

    How do you analyze the SCR for this circuit???

  • Colin Mitchell

    Let me explain why this is the worst circuit on the internet. Not only has it been designed by
    T.K.HAREENDRAN who states he is a “professional electronics engineer” with many circuits in many magazines, but it will blow up the transistors.

    The circuit starts by connecting the battery and the 100n prevents voltage appearing on the base of the base of the first transistor.
    This means the first transistor is not turned ON and both T2 and T3 are not turned ON.
    When the tilt sensor allows current to flow into the base of the first transistor, it is turned ON
    The tilt sensor will only turn it on a small amount and will not damage the transistor.
    But as the transistor turns ON, a voltage develops across the 10k resistor and this allows T2 to start to turn ON.
    It turns ON with a small amount of current into the base but 100 times more current flows in the collector-emitter leads and this current begins to turn on T1.
    T1 now receives 100 times more base current and this action continues until both transistors are fully turned ON.
    There is no current limiting resistor in the circuit and both transistors WILL BLOW UP.
    At the same time T3 is turned on FULLY and it has no current-limiting resistor and it will BLOW UP TOO.
    This makes it with worst circuit on the web.

  • Colin Mitchell

    Go to my website TALKING ELECTRONICS and you will see pages of faulty circuits designed by T.K.Hareendran. He doesn’t have a clue about designing a circuit.

    ” I consider this precious space as a platform for talking & learning about electronics.”

    And learning about HOW NOT TO DESIGN A CIRCUIT !!!!!!

    Touch the two terminals together and let me know what happens
    Are you mad? Who can touch the needles inside a sealed bottle?
    In your instructions you say:When the sensor assembly is tilted, both needles inside the sensor (bottle) are short circuited by the water

    YOU are the one that mentioned SHORT-CIRCUIT!

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