Alt-BEAM Archive
Message #10551
To: beam@sgiblab.sgi.com
From: Ben Hitchcock beh01@uow.edu.au
Date: Mon, 21 Feb 2000 14:22:30 +1100 (EST)
Subject: [alt-beam] Re: FRED1.1 SE
Hi,
> Kyle breadboardd the FRED1.1 Circuit over the weekend, and it seems to
> be more efficaint than the standard FLED, even running a few motors that
> the FLED would not.
Good stuff! I'm glad to see others trying this circuit out.
> Because several of projects are in stall mode right
> now, waiting for parts, cash, and so on, he spent several hour playing
> with various versions. Changing resistors and so on. Finally he came
> back the orignal design but added an LED and 47uf 10v cap in parallel
> with the motor. Now the Motors really fly.
I'm glad that the resistor values as shown on the diagram were
experimentally tested to be the 'best'. I am a firm believer in the TLAR
principles of engineering (for the non-initiated, TLAR stands for "That
looks about right") so any confirmation of my values is appreciated.
> Can anyone explain way this seems to work so well?
At a rough guess, I'd say that the cap is storing up energy between pulses
ofthe motor. Pulses? I hear you say?
Well, most DC motors have brushes that contact a rotating armature. When
the armature is spun, the brushes 'commutate' the current so that the
force exerted by the magnetic field created by the armature is always in
the one direction.
In english, the brushes 'turn on' when the rotating bit is in the right
place, which results in current spikes.
I would try getting rid of the LED altogether, and only having a cap
across the motor. This will enhance the effect (if it is what I think it
is).
Good luck!
Ben
10552 Sun, 20 Feb 2000 21:25:40 -0600 [alt-beam] Re: Direct-Drive LCDs beam@sgiblab.sgi.com SG digikey has them for about $0.99
i have 6 of them myself.
i think Lee has the part number listed on his site. If not email me and
i'll dig it up.
At 07:43 PM 2/20/00 -0500, you wrote:
>Does anyone know of a source of direct-drive LCD's (the ones used by Lee
>Golden to make LCD name tags
>http://www.geocities.com/leemon1/Bots/LCD/lcdname.htm
>)?
>
>I checked BGMicro's catalog and they don't have any. I searched the web,
>and found Optrex Corp., but there's no ordering or contact info.
>
>If anyone has any lying around, I would like to purchase up to 10 of
>them. Please, contact me in private by e-mail, if you are willing to
>sell some.
>
>Best regards,
>
>Victor
>
>
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