Persistence of vision wheel

[Macgman2000]

I have an application for persistence of vision graphics on a spinning platform. I have no experience with this. Also this wheel is spun up and left to spin down, it is not sustained speed. Does anyone have experience with this topic? I am using a 16F1827 MCU and 5 LEDS arranged linearly. Is there a way to determine RPM without using hall/reed switch and magnets?

Any help or info would be appreciated.

Nick

[Ramius]

Only other option would be an encoder on the shaft and an opto-interupter.

[Dave]

An accelerometer and an a/d channel if the wheel is turning purpindicular to earth's gravity.

[ardhuru]

This is a typical 'propeller clock' type application. You will need to use something to determine not just the RPM, but also to know when to begin displaying your frame per revolution, or else your graphics would get garbled.

You can easily use IR to generate your index pulse; Mount the continuously lit IR LED on the chassis, and an IR detector on the spinning platform. Align them such that they see each other once every revolution.

Regards,

Anand

[rsocor01]

You can easily use IR to generate your index pulse; Mount the continuously lit IR LED on the chassis, and an IR detector on the spinning platform. Align them such that they see each other once every revolution.

Or mount both on the chasis in such a way that the spinning LEDs will block the path between them once every revolution and you are set.

[ardhuru]

No, that wont work. The information that the beam has been detected/broken is needed on the rotating assembly. Getting that information on the fixed chassis will serve no purpose.

Anand

[Pimentel]

Look my project about POV
http://www.picbasic.co.uk/forum/content.php?r=284-BigPIC4-Dev-Board

Pimentel