Alt-BEAM Archive
Message #09651
To: beam@sgiblab.sgi.com
From: "Timothy Flytcher" flytch@hotmail.com
Date: Mon, 31 Jan 2000 10:30:52 PST
Subject: [alt-beam] Re: which motors should I use?
> > free from your local pager company if your lucky.
>
>How do you accomplish this feat?? Why would they give away motors for free?
>-William
>
A pager company sells pagers and service... they also contract the pagers
agenst damages... sometimes it is cheeper to give the client a new pager
than it is to fix their old one ... the old broken one goes into a box ...
if the company has been in service for a wile their box may be getting full
and there for unneeded... just ask if you can have/buy their unfixables...
say $0.50 each??? the worst they can say is no... if they say yes then you
have some disassembling to do.. the end product is one nice little motor
from each pager... some will be trash but hay the price is right :)
Timothy...
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9652 Mon, 31 Jan 2000 10:52:38 -0800 (PST) [alt-beam] Re: which motors should I use? beam@sgiblab.sgi.com "Leonardo Boulton F." My father had a Motorolla Startac mobile phone, wich comes with a
vibrate function. It has a small motor, very very tiny inside... So,
the phone died last month and I made some surgery taking out that
motor. Does any body knows if it is any good?. The thing is I have only
one of this motors (maybe I get lucky and my mobile dies too :) )....
Any other motor I can use for the photovore?. I mean, the main question
would be: Can I build a photovore robot with two diferent motors
(diferent type: brand, etc.)?....
Leo
=====
I'm here... http://geocities.com/l.boulton
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9653 Mon, 31 Jan 2000 11:17:11 -0800 [alt-beam] Re: Bicore question beam@sgiblab.sgi.com Bruce Robinson > "Phillip A. Ryals" wrote:
>> When you are using resistor values in the Megohms,
>> the flux can sometimes make a difference.
> How exactly are you suposed to wash it off?
It depends on the flux. Water soluble fluxes are the most common
culprits, and they wash off (obviously) with water. I haven't used this
type of flux, but I suspect a damp sponge would be your best bet. In my
case, I use rosin flux: I find ordinary cleaning solvent on a small pad
made of cotton cloth does the trick. I don't know what I'll do if I ever
get into double-sided boards.
>> did you install a decoupling capacitor across
>> your + and - supply near the chip?
> nope. does this definitely make a big difference? Should I just plan
> on it for every circuit I build?
Sometimes you can get away without it, but it is highly recommended by
chip manufacturers. The rule is: put a decoupling capacitor near every
logic chip. This information is buried away in manufacturer's data books
... you rarely hear about it because everyone assumes you know about it.
Motorola's data book lists specific instances where such capacitors are
essential. Here's the case of particular interest to BEAMers:
"4. Bypass Schitt-trigger devices with slow input rise and
fall times. The slower the rise and fall time, the larger
the bypassing capacitor. Lab experimentation is suggested."
I always use 0.1 uf capacitors, as BEAM applications use extremely slow
rise and fall times.
>> did you "do something" with any unused chip INPUTS?
> I didn't do this either. Kinda misunderstood your question though.
> Should they be connected, or shouldn't they?
Sorry. Again, the data books call for all unused CMOS inputs to be
connected to something ... ground or Vcc. If they are allowed to float,
they can start to oscillate. This consumes power and generates "noise"
that can affect the other devices in the same chip. I make it a habit to
connect all my unused inputs to ground just for the sake of consistency.
Don't forget you've done it if you later decide to use the device for
something else.
Unused outputs are always left unconnected ... connecting them to either
supply line would most likely cause a short circuit & fry the chip.
>> are you using LED's to check your microcore behaviour? Are they
>> installed right way around?
> yup, to both questions. :)
Ah, a challenge then. I didn't ask the most obvious question, and I
should have, because I've been caught by this an embarassing number of
times.
Are your connections correct? I keep a small box of fried chips on my
workbench to remind me of the number of times I told myself "of course,
dummy", only to find out I was wrong.
My own approach is to put aside whatever diagram or schematic I was
using to build the circuit, and using only my breadboard / circuit board
/ free formed circuit as a guide, re-draw the schematic. I then compare
this to the original diagram. line by line, looking for discrepencies.
If after all this you still aren't getting results, we'll have to get
into some serious debugging. Just keep reminding yourself ... if you got
it to work on the breadboard, then you can get it to work off the
breadboard :) Sometimes it takes patience.
Regards,
Bruce
9654 Mon, 31 Jan 2000 12:58:16 -0700 [alt-beam] Flux cleaning (was: Bicore question) beam@sgiblab.sgi.com "John A. deVries II" At 12:17 PM 1/31/00 , Bruce Robinsonwrote:
>Water soluble fluxes are the most common culprits, and they wash off
>(obviously) with water. I haven't used this
>type of flux, but I suspect a damp sponge would be your best bet.
Actually, running it through the dishwasher (presuming no water-damageable
parts) works very nicely. The problem with using a sponge is that the end
of components and wires sticking through the PCB tend to tear the sponge to
shreds. I believe I've seen Tilden use a toothbrush on occasion.
Z
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