Alt-BEAM Archive

Message #07906



To: beam@sgiblab.sgi.com
From: James G Watt jim@kinetic-arts.demon.co.uk
Date: Mon, 22 Nov 1999 13:33:19 +0000
Subject: [alt-beam] Re: another new beam web site in 3D B-Movie Vision.


In article <19991119062350.26806.qmail@hotmail.com>, Timothy Flytcher
writes
>Question? I noticed the pad feet on your widow ... doesn't this make it trip
>or hang up???
Yes it does a bit. I may change that. I had wire feet at first but they
skidded to much - then I tried coating them in a rubbery glue. That gave
them to much grip so they wouldn't skid at all and usually just stuck
solid. The pads work well on a smooth surface but will get caught on
irregular surfaces so I'll continue to experiment with different
materials. Any suggestions?
--
James G Watt

http://www.kinetic-arts.demon.co.uk
Part of the Video Arcade Game Collectors WebRing.

You are in a maze of twisty little passages, all alike.



7907 Mon, 22 Nov 1999 10:43:29 -0800 [alt-beam] Re: psh question #2 "'beam@sgiblab.sgi.com'" Wilf Rigter

I'm back! Justin, you are correct about the psh motor outputs, that they
are steady state high or low when the head motor is actively "turning" but
the outputs oscillate in phase when the head is "locked" on. I assume you
want to generate a steady state active low enable signal when the outputs
oscillate. One very simple way to do that is to detect that the current in
the motor drops to zero at that time.Since all the motor current flows into
the Vcc pin, a PNP transistor used to sense this current can provide both
indication of motor activity and the active low enable.

The schematic of your filter is one of the "linear amplifier" configurations
which is almost certain to oscillate on it's own. You can demonstrate this
with a slowly varying dc voltage (pot between 0V and +V) at the input and
see if the inverter oscillates when crossing the threshold. Another point to
remember is that using the 1.5K and the .1uf cap for a filter (Nu)
integrates high frequencies and generates an analog voltage across the cap
proportional to the duty cycle of the waveform. When that voltage is near
the threshold, it causes the inverter to go into the linear region,
oscillating just like the applying the dc voltage in the previous demo.

There are lot's of other solutions and I will whip up another one at lunch
~2hr from now.

Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
tel: (604)590-7493
fax: (604)590-3411
> <> -----Original Message-----
> From: BotDoc [SMTP:botdoc@yahoo.com]
> Sent: Sunday, November 21, 1999 9:00 PM
> To: beam@sgiblab.sgi.com
> Subject: psh question #2
>
> The attatched schematic is the best that I have been
> able to come up with for controling enable pins with a
> power smart head. It does ok in bringing the voltage
> up to v+ and dropping it to ground. It is also ok at
> filtering out the oscillating of the head when it is
> locked on. there is one thing I can't get figured
> out. that is when the head position is being moved to
> the side, right before it triggers to fire the motor,
> or led in my case, it becomes unable to filter out the
> oscillation of the head. This only happens when it is
> being turned one way. Any ideas on how to improve it
> to control an enable pin with?
> Justin
>
>
> =====
> A motor is a robot waiting to happen
> __________________________________________________
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> Bid and sell for free at http://auctions.yahoo.com << File: filter.gif >>



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