Alt-BEAM Archive

Message #05264



To: beam@sgiblab.sgi.com
From: Chiu-Yuan Fang chiumanfu@home.com
Date: Mon, 12 Jul 1999 10:03:11 -0700
Subject: [alt-beam] Re: power loss>>advice needed


Are you connecting the LED's to the motor h-bridge outputs? Try connecting them
to the microcore:
http://www.geocities.com/SouthBeach/6897/ucore.jpg
and remember to install series resistors.

Chiu

SG wrote:
>
> I need y'alls help with a problem that has been bugging me for about 3
> weeks now.
> the rear servo on my walker has considerably less power than the front one.
> but (get this) only when the battery is fully charged.
> When the battery is about 10 min from running out the servos werk perfectly
> and the walking is grand to watch.
> I have:
> >>rebuilt the rear H-bridge 4 times (replaceing the 123AP "replacment"
> transistors with actual 2N3904's)
> >>resoldered the IC connections
> >>replaced the IC
> >>replaced the Servo
> >>replaced the the .22 Caps
> >>kicked the cat in frustration
> I just don't understand why the thing werks great when the battery runs
> down from peak charge.
> The battery is a 4.8V (both schematic & servo manufacturer call for 4.8V)
> I have two and have alternated them with no change in results. They are
> Radio Shack Ni-Cd 4.8V 600mAh
> I really don't know what else to do.
>
> NOTE: i tried disconnecting the LED's connected to rear servo thinking this
> might be the sorce of a short or something. the rear servo then had about
> 2X as much power than the front servo (instead of 1/2 the power). This
> really messed up the walking gait and the walker just kinda shook and never
> worked itself into walking. (even triggered reverser cap somehow a few
> times without activating reverser switch) I figured all this must have
> happened because the Front servo still had it's LED's connected therfore
> making an unequal power draw.
> Please... any advise would be great!
> Thanx!
> -Sparky

--
Chiu-Yuan Fang
chiumanfu@home.com
ICQ=5614919
http://www.geocities.com/SouthBeach/6897/beam2.html

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