Joyrider bike POV

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By Collin Cunningham
Posted 2008/03/05 @ 12:09 pm
Category Fun & Games

Wow – ultracompact smiley bicycle spoke POV!

Designer Moritz Waldemeyer has created Joyrider, a product that creates illuminated smiley faces on rotating bicycle wheels.
Joyrider consists of two electronic devices that clip onto wheel spokes. They measure the speed of rotation and emit LED light to create the illusion of a stationary smiley face as the wheel spins.

They went for Â£2000 @ a charity auction, I’m guessing a bit cheaper as a remake – Link

Related:

SpokePOV Kit – Link

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10 Responses to Joyrider bike POV

Hessel on March 5th, 2008 at 3:19 pm said:

How do they “measure the speed of rotation” ?

Is there a magnet involved and a hal effect sensor ?

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Mr Dan on March 5th, 2008 at 3:36 pm said:

I should imagine it would be using an accelerometer.

When the sensor is at the top of the wheel, it is pointing one way, thusly reading +g

Rotate the wheel 180deg and the sensor will be the other way up, reading -g

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Hessel on March 5th, 2008 at 3:41 pm said:

Sounds good !

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DU on March 6th, 2008 at 4:51 am said:

An accelerometer would be too complicated–you are forgetting radial acceleration. Even finding the points of max and min a would be a pain, let alone taking into accounts real changes in speed.

A magnet, or better yet a simple brush, would be much easier to manage.

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Hessel on March 6th, 2008 at 12:28 pm said:

Would the small three pin device with the text:

41A
648

be the key to an answer what is used here ?

Could it be a bipolar hall effect transistor….

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Mr Dan on March 6th, 2008 at 3:19 pm said:

Hessel,

Which image are you looking at? I can’t make out enough detail to read the text on the components :-/

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Mr Dan on March 6th, 2008 at 3:51 pm said:

Just had a look on ladyada.net, and it most probably is a Hall effect sensor:

http://ladyada.net/make/spokepov/makespokepov.html

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Hessel Tigchelaar on March 6th, 2008 at 10:45 pm said:

@Mr Dan

I found this photo with a slightly higher resolution:
http://bp0.blogger.com/_i9rXZ8BZKVY/R8yT_cFZHMI/AAAAAAAAAHQ/HqyJP_pBY2Q/s1600-h/IMG_6117.jpg

I also expect it is a Hall Effect sensor. I was wondering if it would be possible to apply this on a Car, where there is no place to put the magnet close to the sensor.

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Moritz Waldemeyer on March 8th, 2008 at 3:12 am said:

Hi guys, it is indeed a hall effect sensor (unipolar). The disadvantage of this is that the sensor uses more battery than the LED itself. So far I haven’t found one with a decent current consumption, if anybody knows one, please post it…
The other components are a PIC, LED, resistor, two batteries.

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Hessel on March 9th, 2008 at 2:38 pm said:

Allegro A3213 and A3214
Micropower, Ultra-Sensitive Hall-Effect Switches look good !

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