Write on the Thin Air

Introduction: Write on the Thin Air

With the dc speed control, a micro controller and six vertical LEDs from which i can display any alphabet or a sentence in a 360 degree circle.
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    Akhilesh Koul

    For calculating rpm u want 2 use reed switch right? correct me if i m wrong.

    But there are other methods ( less technical or i can say a little kludge method) like which i had used shown in picture, i pre-defined the the time of the LED using micro-controller and clicked the photograph from above to measure the angle( so i have angle and time => rpm). After 2-3 shots i got the perfect click.


    Why not (and this is just a question not telling you how to do it) mount a magnet to a point on the motor and mount a reed switch to the PCB?

    Whenever the reed switch is triggered the circuit has travelled in a complete circuit once. Start a timer when the switch is triggered and when it gets triggered the next time you know how long the rotation took. Use that to calculate LED time for the next rotation.

    Rinse and repeat. The speed will stabilise rapidly and you won't be relying on fixed timings.

    I can't see why that wouldn't work, if you can let me know :)

    Akhilesh Koul

    1. First you have to fabricate the whole setup and mount it on DC motor.

    2. Here comes the tricky part that how the join two PCB boards. Take two metal sheet and solder one side to PCB and other site to plastic part of PCB with the help of Strong adhesive.

    3. Now when the motor rotates, it produces very strong vibrations due to load mounted on it, so create a POP mould to fix motor in it.

    4. Now calculate the rpm of motor, and not the time taken to complete one degree rotation.( as diff voltages produces different rpm so fix the voltage say 5 V)

    5. At last program the micro-controller with the right amount of delay in between the blinking of LEDs.

    N.B. To make it balance add some weight on the other side, as in this case dead 1.5 V AA size battery.

    The rpm produced is so large to make one rotation in less time than persistence of vision i.e. 1\16th of a second, so the LEDs blinked at zero degree remain there with the LED blinked on say 60 degree.

    Hope you got the working principle behind it, and how it displays the letters.

    Any other query please feel free to write.


    9 years ago on Introduction

    That's nice, but it would be really cool if you could include details of how you made it.