Alt-BEAM Archive
Message #06126
To: beam@sgiblab.sgi.com
From: Darrell Johnson beamtastic@yahoo.com
Date: Fri, 17 Sep 1999 13:14:29 -0700 (PDT)
Subject: [alt-beam] Re: BG Micro Motors
I'd be willing to trade a few of mine for somebody's soul... I think I
have like 9 of them left.. if you can gather up 3 souls, you can have
them all!
:)
Darrell
--- Gadagada@aol.com wrote:
>
> Ah, the famous BG Micro Motor source conundrum.
> Your only hope is to find
> someone on the list who has some and shamelessly
> bribe them (your soul might
> be a fair trade for a few).
===
_______________________________
BICOREEOS..They're BEAMtastic!!
http://home.pacbell.net/wundoba
__________________________________________________
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Bid and sell for free at http://auctions.yahoo.com
6127 Fri, 17 Sep 1999 16:15:34 -0700 [alt-beam] Re: power_smart_head fest "'beam@sgiblab.sgi.com'" Wilf Rigter It's always satisfying to solve a problem but I should have suggested that
solution first. The archenemy of digital logic in general and beam quasi
digital/analogue/power circuits in particular is lack of power supply
decoupling. The problem is the inductance of the power leads which couples
switching transitions and motor current through voltage drops from one part
of the circuit into another part as noise on the power pins. With a local
power supply decoupling cap that noise is filtered and the motor current
spikes are supplied by the stored energy of the cap. I routinely add
decoupling caps on all my circuits so these problem never appear. However I
incorrectly assumed that everyone does the same and invariably leave out the
decoupling caps in my schematics.
So I hope that despite some frustrations this has proved to be a useful
exercise and a step on the learning curve (if I will only remember to add
the caps to my schematics in the future.)
regards
Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> -----Original Message-----
> From: Scott Burns [SMTP:s-burns@uiuc.edu]
> Sent: Friday, September 17, 1999 11:51 AM
> To: beam@sgiblab.sgi.com
> Subject: RE: power_smart_head fest
>
> Success! I double checked all components--they were all correct. I tried
> the new resistor values you suggested--no improvement. Then I read about
> the high frequency problem and strapped a big honkin' capacitor across my
> power supply and it worked! I have one of those Elenco "Precision" quad
> power supplies. I can't see any ripple on my scope, but maybe there's a
> high frequency noise in there somewhere. I _am_ using V1 of the PSH,
> aren't
> I? Should it be so sensitive?
>
> Thanks for all your help!
>
> Scott
>
> At 08:51 AM 9/17/99 -0700, you wrote:
> >Well.....
> >
> >I have protoboarded the ps head exactly the way it is shown on your
> webpage
> >and it works perfectly for me. I have tried a variety of chips and
> >component values and it just keeps on working. It certainly is more
> >sensitive with photodiodes and more active with the 1K resistors removed
> but
> >LDRs with or without 1K resistors work fine too. Are you certain of the
> >component values? Capacitors can have a wide tolerance but even so that
> >should not produce the problem you show. If the LDRs are very low value
> (100
> >ohm in moderate light) the 1K resistors may interfere. If the 1K
> resistors
> >are 10K that would also explain the behaviour in bright light. One other
> >experiment is to swap the 10M and 5.6M resistors: note the difference in
> >behaviour in low light and when the LDRs are balanced. The best "tuning"
> of
> >the circuit ended up with the 5.6M resistor changed to 10M and the 10M
> >resistor changed to 9.1M. The absolute values are less important than the
> >ratios and the original circuit works quite well but is somewhat
> >conservative (and snoozy) compared to the fine tuned values.
> >
> >One more comment: the PS head V1 is robust and stable and the high
> frequency
> >problem I referred to earlier is easily controlled with a 0.1 uf cap
> across
> >the motor. The PS head V2 and V3 circuits require critical adjustments
> and
> >are not recommended for the faint of heart. Since the objective of the
> later
> >versions was to control high frequencies, the much simpler V1 with a cap
> >across the motor is the preferred circuit.
> >
> >
> >
> > Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> > tel: (604)590-7493
> > fax: (604)590-3411
> >
> > > -----Original Message-----
> > > From: Scott Burns [SMTP:s-burns@uiuc.edu]
> > > Sent: Thursday, September 16, 1999 9:16 AM
> > > To: beam@sgiblab.sgi.com
> > > Subject: RE: power_smart_head fest
> > >
> > > At 06:12 PM 9/10/99 -0700, you wrote:
> > > >Hello Scott,
> > > >
> > > >Tell us more: what components? which schematic? what motor? matched
> LDRs?
> > > >
> > > >best regards
> > > >
> > > > Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> > > >
> > >
> > > OK, I've described it in detail (including scope readings) at
> > >
> > > http://www.designbyalgorithm.com/circuit.htm
> > >
> > > > > -----Original Message-----
> > > > > From: Scott Burns [SMTP:s-burns@uiuc.edu]
> > > > > Sent: Friday, September 10, 1999 7:05 AM
> > > > > To: beam@sgiblab.sgi.com
> > > > > Subject: Re: power_smart_head fest
> > > > >
> > > > > Dear Wilf:
> > > > >
> > > > > The virtual beam workshop sounds great. I tried building the PSH
> and
> > > was
> > > > > able to get the square waves to the motor to change duty cycle
> with
> > > > > changes
> > > > > in relative LDR illumination, but they were always in phase. The
> motor
> > > > > never saw a voltage differential across it. I'm anxious to figure
> out
> > > what
> > > > >
> > > > > I did wrong.
> > > > >
> > > > > Regards, Scott
> > > > >
> > > > >
> > >
> > > ------------------------------------------
> > > Prof. Scott A. Burns
> > > Dept of General Engineering and Civil Engineering
> > > University of Illinois at Urbana-Champaign
> > > 104 S. Mathews, Urbana, IL 61801
> > > Phone 217/333-1618, FAX 217/244-5705
>
> ------------------------------------------
> Prof. Scott A. Burns
> Dept of General Engineering and Civil Engineering
> University of Illinois at Urbana-Champaign
> 104 S. Mathews, Urbana, IL 61801
> Phone 217/333-1618, FAX 217/244-5705
6128 Fri, 17 Sep 1999 17:53:55 -0700 (PDT) [alt-beam] Re: BG Micro Motors beam@sgiblab.sgi.com James Taylor I guess I'll part with my collection of BG micro
motors, I'm moving on to big walkers. I have 5,
asking 30 dollars each. Or trade for stuff.
--- Gadagada@aol.com wrote:
> In a message dated 9/16/99 10:49:59 PM Eastern
> Daylight Time,
> dilbertpete@hotmail.com writes:
>
> << Hello Everyone,
> I am looking for a source of BG Micro Motors for a
> microcore. Does anyone
> know where I can find them??
>
> Thank you very much
> -Pete >>
>
>
> Ah, the famous BG Micro Motor source conundrum.
> Your only hope is to find
> someone on the list who has some and shamelessly
> bribe them (your soul might
> be a fair trade for a few). Or, at the risk of
> death by firing squad, you
> could email Nihon (I think that's it) and tell them
> you are a defense
> contractor looking to buy massive quantities of 30
> rpm, 3v, very efficient DC
> gearhead motors and would like some samples. Either
> way, good luck.
>
>
>
> Gary
>
===
Everything I say can mean one of two things...If something I say makes you mad....I meant it the other way.
James Taylor
URL: http://fly.to/springmeadows
__________________________________________________
Do You Yahoo!?
Bid and sell for free at http://auctions.yahoo.com
6129 Friday, 17 September 1999 8:17 Re: non-beam but electronics related beam@sgiblab.sgi.com Bumper314@aol.com
>In a message dated 9/16/99 12:13:22 AM Pacific Daylight Time,
>davidperry@geocities.com writes:
>
>> are you thinking what i think your thinking, stuff buying a $150 Rio MP3
>> player? If you find anything out or build such a circuit please contact
me!
>> Sorry to clog up the list with this.
>>
>
>Well i have the schematics and all...just was looking for someone else who
>has worked with them too...oh well
>
>steve
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