Make an LVDT with soda straws

Science Technology

It’s the McLVDT, a linear variable differential transfomer, made from McDonald’s straws. The creator writes:

I made a primary coil on a normal sized straw, and made two secondary coils on the outside of the larger McDonald’s straw. Since the McStraw is large-bore (perfect for those thick high calorie shakes), the smaller straw with the primary winding fits nicely inside. The position of the inner straw can be determined by examining the amplitude and phase of the combined signals of the secondary coils, which is shown in raw form on the oscilloscope.


10 thoughts on “Make an LVDT with soda straws

  1. Matt Mets says:

    Ha! This might make a nice linear movement sensor as well!

    1. Bob D says:

      LVDTs are for measuring linear displacement.

  2. Steve Poling says:

    If you live in a town big enough to have a place to buy Bubble Tea, buy yourself a tasty beverage. And save the straw. If you think the McDonalds milkshake straws are large-bore, you’ve never enjoyed Bubble Tea.

  3. Kevin Rouviere says:

    Bubble Tea? I’ll have to check that out. Thanks!

  4. Kevin Rouviere says:

    I’ve since made a detailed article about this.

    It can be found here

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Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. His free weekly-ish maker tips newsletter can be found at

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