Make: Online : Joyrider bike POV

Joyrider bike POV

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 £2000 @ a charity auction, I'm guessing a bit cheaper as a remake - Link

Related:

SpokePOV Kit - Link

Related:

Comments

Oldest comments listed first.

Posted by: Hessel on March 5, 2008 at 3:19 PM

How do they "measure the speed of rotation" ?

Is there a magnet involved and a hal effect sensor ?

Reply to this comment

Posted by: Mr Dan on March 5, 2008 at 3:36 PM

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

Reply to this comment

Posted by: Hessel on March 5, 2008 at 3:41 PM

Sounds good !

Reply to this comment

Posted by: DU on March 6, 2008 at 4:51 AM

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.

Reply to this comment

Posted by: Hessel on March 6, 2008 at 12:28 PM

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....

Reply to this comment

Posted by: Mr Dan on March 6, 2008 at 3:19 PM

Hessel,

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

Reply to this comment

Posted by: Mr Dan on March 6, 2008 at 3:51 PM

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

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

Reply to this comment

Posted by: Hessel Tigchelaar on March 6, 2008 at 10:45 PM

@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.

Reply to this comment

Posted by: Moritz Waldemeyer on March 8, 2008 at 3:12 AM

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.

Reply to this comment

Posted by: Hessel on March 9, 2008 at 2:38 PM

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

Reply to this comment

Subscribe to MAKE Magazine!

Subscribe today, save 42% and get web access to MAKE free. MAKE Digital Edition is available only to subscribers.

$34.95 / 1 year
(4 Quarterly Issues)

Subscribe now

Void your warranty, violate a user agreement, fry a circuit, blow a fuse, poke an eye out. Make: The risk-takers, the doers, the makers of things... Welcome to Make: Online!

Make: television is here! Visit makezine.tv or iTunes to see all the episodes.

Connect with MAKE

	MAKE on Facebook Visit our Facebook page and become a fan of MAKE!
	MAKE on Twitter Follow our MAKE tweets!
	MAKE on Flickr Join our MAKE Flickr Pool!

make_tips on Twitter

MAKE's RSS feed is here.
Add MAKE to iGoogle - GoogleGoogle.
How to add MAKE to your RSS reader - Real simple.
Add MAKE on FriendFeed

Why advertise on MAKE?
Read what folks are saying about us!

Click here to advertise on MAKE!

MAKE wins Treehugger Best of Green Award

Make: Online authors!

Gareth Branwyn, Chris Connors (guest author), Collin Cunningham, Marc de Vinck, Peter Horvath (intern), Kip Kay, Goli Mohammadi, John Park, Sean Ragan, Becky Stern, Phillip Torrone

Suggest a Site!

Current Podcast

Weekend Project: Fire Piston Make your own fire starter that uses compressed air and burns at 500 degrees! Thanks to Bill Gurstelle for showing us this at Maker Faire. To download The Fire Piston MP4 click here or subscribe in iTunes. Pick up... More...