Alt-BEAM Archive
Message #04277
To: beam beam@corp.sgi.com
From: Sean Rigter rigter@cafe.net
Date: Fri, 04 Jun 1999 23:29:23 -0700
Subject: [alt-beam] Power Smart Head (Re:Head)
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Hi Steve,
You reminded me of the MonoHead circuit I designed a short while ago
which, like a normal Bicore Head, required motor power even when locked
on to a target. Since I am all charged up with new ideas after a dose of
the BEAMant circuit (I feel I wasted a couple of months not having seen
it before) I redesigned the MonoHead circuit which now conserves motor
power in several ways including turning off the motor current when
"locked" on.
The Power Smart Head
This head circuit uses a High/Low/Oscillator (HLO) which is a
comparator with capacitive feedback that generates a High or a Low
output when the photocells are unbalanced and Oscillates when each
photocell receives roughly the same light. The motor driver consists of
a bridge with a direct coupled buffer and a differential Nv buffer. The
bridge drives the motor in one direction or the other when the
photocells are unbalanced and the HLO is either high or low. When the
photocells are slightly unbalanced, the motor driver pulses conserving
power to make small changes But when both photocells are equally
illuminated, the HLO oscillates at about 10Hz. At this frequency the
differential Nv buffer and the direct buffer of the bridge are the same
polarity, the motor is stopped and the brake is on. This is a low power
standby mode which requires just a few ma of supply current. When the
light conditions are rapidly changing the motor may reverse back and
forth but while reversing polarity, the bridge has a momentary dead spot
which also reduces wasted power.
I have only done a few bench tests and have not yet build a Head with
this circuit but the design seems work ok. Since only 4 inverters (as
few
as 3 actually) are needed, it is possible to make a 2DOF head using only
one HC240 or AC240 chip. If you require higher current, an HC139
Z-bridge may be connected to the motor driver outputs with the unused
HC139 outputs connected to a LED to indicate the locked condition.
Finally the unused inverters can be used for other functions such as a
low pulse rate seek oscillator to scan for light sources
enjoy
Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
tel: (604)590-7493
fax: (604)590-3411
> -----Original Message-----
> From: Bumper314@aol.com [SMTP:Bumper314@aol.com]
> Sent: Friday, June 04, 1999 3:04 PM
> To: Wilf.Rigter@powertech.bc.ca
> Subject: HEAD
>
> Hello, I am stumped. I am trying to think how mark tilden make his solar
> heads so that once they locked onto the light source they just shine an
> LED
> rather then waste the energy to move the motor to the same place...I am
> trying to experiment with the photopopper circuit and the 74HC139, but
> without any success. Would you have any ideas? Thanks for your time
>
> Steve
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4278 Fri, 4 Jun 1999 23:30:35 -0700 (PDT) [alt-beam] The End of Unicore BEAMAnt Schematic Confusion beam@sgiblab.sgi.com BotDoc
--- Jason - wrote:
Here is a direct link to the "corrected" BEAMAnt
schematic. The astute observer will notice that Tilden
himself scratched out "the mystery part" and replaced
it with a little error annotation. Look here
http://www.serve.com/heretics/handdrawn.jpg
>
>
>
> >From: Jean auBois
> >Reply-To: beam@sgiblab.sgi.com
> >To: alt-beam@egroups.com
> >CC: beam@sgiblab.sgi.com, rix.g@bmts.com
> >Subject: Re: [alt-beam] Better Unicore BEAMant
> schematic
> >Date: Fri, 04 Jun 1999 13:03:23 -0600
> >
> >At 10:24 AM 6/4/99 , Jesse Meers wrote:
> >
> > >Well, everyone I drew this up a couple of days
> ago, its in jpg format. I
> > >would have put more info on the circuit, but that
> can be figured out from
> > >Ian's site, and the actual values havnt been
> verified yet. Anyone want to
> > >verify the values??
> >
> >I hate to tell you, but the thing that looks like a
> double-diode thingy
> >connecting ground in the lower right hand corner to
> another pin and the
> >motor on your drawing is the result of a
> misunderstanding. Originally,
> >there was a line drawn there but it wasn't erased
> -- merely scribbled over.
> > In other words, the right-hand motor straddles
> pins 12 & 14 and isn't
> >connected to anything else.
> >
> >Please make this correction or people will forever
> after be confused!
>
>
> we are getting quite confused here...in your
> website...mark posted his
> beamant article in the teluride meeting...that
> article has a picture of a
> topology of mark's beamant...on the left motor there
> is a two diode put back
> to back....how can u explain this though the hand
> drawn schematics is an
> error on it.....care to explain this
> jeean...thanks(i am just
> suggesting...no offence)
>
>
>
______________________________________________________
>
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