Alt-BEAM Archive

Message #02210



To: "'beam'" beam@corp.sgi.com
From: "Feser, Jason" jfeser@ea.com
Date: Sat, 10 Apr 1999 17:47:27 -0700
Subject: [alt-beam] please ! help me stop my head from squealing!


Hey gang.

I've breadboarded a 2dof head and have a question. Is the bicore
supposed to squeal when there is no definate light hitting one of the
photodiodes? What happens is this - with no direct lightsource (flashlight)
shining on one of the photodiodes, something in my circuit sounds like its
squealing. It sounds like it's eminating from the h-bridge i'm using (the
6 transistor type found on Ians site) but my room is so noisy, it's hard to
localize. Is this a normal state? If I shine a light directly on one of the
photodiodes, the squealing persists and the motors turn as they should...

Also, are 'heads' supposed to work in normal light conditions??? Are
they supposed to activly seek light? Mine just sits there unless you shine
a farily strong light source directly at a photodiode..

And finally, can someone explain the pro's and con's of using photodiodes
over CDS cells?

Please help. Im rapidly developing a headache.



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