Puff Switch Brick

This is a great switch for someone who for whatever reason does not have the ability to use their hands. The switch is closed by blowing into the straw, which inflates a balloon and closes a sensitive pressure switch. This switch was heavily inspired by Forrest Mims III. His many books about electronics are inspiring in their brilliance and simplicity. The puff switch is included in Engineer’s Mini Notebook Sensor Project. A PDF of this book can be viewed at: https://archive.org/details/Engineers_Mini-Notebook_Sensor_Projects_Forrest_Mims

It also owes credit to Erik Herman of The Physics Bus. He was the inspiration for the plastic bottle push switch element.

Parts Needed:

    • balloon
    • plastic soda bottle (you need something that is plastic and cylinder in shape)
    • rubber band
    • flexible drinking straw
    • large binder clip
    • 3 small binder clips
    • paper clip
    • aluminium foil
    • cardboard


    1. Insert the short end of the flexible drinking straw into balloon. Fold the excess of the balloon’s opening around the straw. Loop a rubber band around a few times to hold everything in place.
    2. Straighten a paper clip and then bend it in half.
    3. Clip the bent paper clip to the short end of a rectangular cardboard brick.
    4. Cut a piece of curved plastic from your soda bottle. It should be slightly longer than the short side of your rectangular brick.
    5. Wrap the plastic in aluminum foil.
    6. Clip the curved piece above the bent paper clip.
    7. Bend the curved piece of plastic back so it clearly does not touch the paper clip.
    8. Use a large binder clip to attach the balloon. The large part of the balloon should rest above the plastic piece and paper clip.
    9. Use a binder clip to hold the balloon in place above the switch.
    10. To turn the switch on, inflate the balloon. The switch should turn off when the balloon deflates.
    11. Label.