Alt-BEAM Archive
Message #10403
To: beam@sgiblab.sgi.com
From: BUDSCOTT@aol.com
Date: Fri, 18 Feb 2000 13:25:59 EST
Subject: [alt-beam] Re: neurotic pvore name stumpy
wow, it took longer in the U.S. it seems. oh, well, i'm never good a
remembering things.
-Spencer
10404 Fri, 18 Feb 2000 13:59:45 EST [alt-beam] More fun questions beam@sgiblab.sgi.com BUDSCOTT@aol.com I'm currently working (yeah! parts are in) on three new robots. one is a
photovore that will use solenoid for locomotion, one is a walker, and one
symet. I have a few Q's .
Q: For the walkers, i bought two motors from MPJA, they run okay on just
one AA. The question is, when i hook up voltage to the incomplete walker
circuit, that needs the three volts, right? so when hook up my 245 motor
drivers, what voltage should they get?
Q: for the symet, i order three 1000uF caps. They're pretty damn small!
should they be any larger than a half an inch or so, cause it looked like all
the other symets i looked at with the 1000uF cap were larger. they're rated
for 6.3v, i hope i got the right kind
Q: with most of my previous questions about solenoids, people said they
had a return spring. Mine don't. it's weird, the armature came seperated from
the core, they just slide in, no spring. any comments? I also can't put a
finger on the current drawn by these puppies, any help?
Thx for any response.
-Spencer
10405 Fri, 18 Feb 2000 11:04:34 -0800 [alt-beam] Geared motors...again beam@sgiblab.sgi.com Bernard Nazari Hey all,
Well, I managed to get my first brain done for my first walker, the only
problem is that I haven't found a motor that will work. I found a couple of
mega-cheap motors at a surplus store, but they have just about enough
torque to turn the gears...that's it. I know I can hack into a servo and do
it that way (and spend $30 on a walker), but I am hoping to not sell my car
to get into this hobby. I'm in the L.A. area, so I'm pretty sure there has
to be something around here. Any ideas? (And I did look at the MECI,
MicroMo, and some other sites, except they don't have the roughly 30RPM@5V
sort of motor that I want.) Anyway, take care and have a good Presidents Day!
Bernie N.
P.S. The circuit works great, thanks to Andrew Miller's site! The motors
are workin' and the LEDs are blinkin'! (Well, that's ignoring the fact that
the motors can't turn the legs yet!)
P.P.S. And to Mark Tilden, three words: You the man!
10406 Fri, 18 Feb 2000 14:17:07 -0500 [alt-beam] Re: pdiode ptransistor? beam@sgiblab.sgi.com "Sathe Dilip" If the circuit elements across which the back-to-back PDs are connected,
change polarity during operation, using a single diode will provide a
near short (with only the forward voltage drop for the diode ~ 0.6 volt)
when the anode is driven positive with respect to the cathode. If you
are using two photo diodes back to back, this problem does not arise.
In a bicore (head) PDs are connected back to back & in parallel with the
timing resistor. The pair also ties the two inverter inputs. The PDs
affect the timing of the cross connected inverters by affecting the RC
time constants when their leakage current changes with light. Depending
on which PD is exposed more to light, the motor gets power in one
direction for a longer duration than the other. This continues till
both the PDs are getting equal amount of light - equalizing the time
constants in both direction - resulting in no effective motor movement.
(This is good in theory - the motor buzzes in practice - when you use a
simple bicore)
If the PDs were connected in parallel with each other instead of in
series, the inputs will not be able to swing to opposite extremes. They
will stay within 0.6 volts of each other. This is probably not the best
example but shows how single photo diodes can affect the working of
surrounding circuitry, if polarity changes are likely.
Dilip
------------------------------------------------------------
Rob wrote:
>
> Could you explain that a little please?
> Rob
>
> Sathe Dilip wrote:
>
> > That' right. Also having the two diodes back to back ensures that
> > (irrespective of the polarity of the associated circuitry) atl east one
> > of them is reverse biased thus offering a high equivalent impedance to
> > rest of the circuitry so that its function is not affected (in an
> > unwanted way).
> > Rob wrote:
SNIP
> > > So is that how the two photodiodes work in a bicore? They are connected
> > > cathode to cathode and when the light hits one side it leaks allowing the
> > > current to flow opposite to its orientation but with the orientation of the
> > > other photodiode. (clear enough I hope)
> > >
--
----------------------------------------------------------------------
The early bird may get the worm, but the second mouse gets the cheese.
----------------------------------------------------------------------
10407 Fri, 18 Feb 2000 14:22:12 -0500 [alt-beam] Re: solarbotics pager mtr+fan beam@sgiblab.sgi.com "Sathe Dilip" One thing to remember in the following configuration is that the
counteracting motor's fan has to have the propeller blades twisted in
the opposite direction to ensure lift. Usually finding a matched pair
of propellers with opposite twist will be difficult.
Dilip
-------------------------------------------
Mike Kulesza wrote:
SNIP
> what voltage? I know, that torque effect will cause the motor nacalle to
> spin in the opposite direction of the propeller, but it could be attached to
> something to prevent it, and only allow vertical motion. Or an even number
> of motors and fans can be assembled to counteract torque effect.
> ______________________________________________________
>
10408 Fri, 18 Feb 2000 12:41:32 -0700 [alt-beam] Re: solarbotics pager mtr+fan beam@sgiblab.sgi.com Dave Hrynkiw At 11:29 AM 2/18/00 , Richard Weait wrote:
Ummm. . . "Pager motor" . . . "12 V (!)" . . . How long
>did you say it ran, Dave? :-)
About 30 seconds! I had it oriented so the airflow went past the motor body
and kept it cooler. Didn't test it to destruction....yet.....
-Dave
---------------------------------------------------------------
"Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
2 vowels. Pronounciation? _SMITH_".
http://www.solarbotics.com
10409 Fri, 18 Feb 2000 14:44:14 -0500 [alt-beam] Re: More fun questions beam@sgiblab.sgi.com "Sathe Dilip" Using the ohms range of your multimeter, measure the resistance of the
solenoid coil. Divide the voltage you want to apply by this value in
ohms. You will get the value of current required to drive the solenoid
from a DC source.
e.g.,
You want to drive the solenoid with 3 volts.
You measure the coil resistance as 6 ohms.
You will draw 3/6 = 0.5 Amps for the solenoid.
Dilip
-------------------------------------
BUDSCOTT@aol.com wrote:
>
> I'm currently working (yeah! parts are in) on three new robots. one is a
> photovore that will use solenoid for locomotion, one is a walker, and one
> symet. I have a few Q's .
>
> Q: For the walkers, i bought two motors from MPJA, they run okay on just
> one AA. The question is, when i hook up voltage to the incomplete walker
> circuit, that needs the three volts, right? so when hook up my 245 motor
> drivers, what voltage should they get?
>
> Q: for the symet, i order three 1000uF caps. They're pretty damn small!
> should they be any larger than a half an inch or so, cause it looked like all
> the other symets i looked at with the 1000uF cap were larger. they're rated
> for 6.3v, i hope i got the right kind
>
> Q: with most of my previous questions about solenoids, people said they
> had a return spring. Mine don't. it's weird, the armature came seperated from
> the core, they just slide in, no spring. any comments? I also can't put a
> finger on the current drawn by these puppies, any help?
>
> Thx for any response.
>
> -Spencer
--
----------------------------------------------------------------------
The early bird may get the worm, but the second mouse gets the cheese.
----------------------------------------------------------------------
10410 Fri, 18 Feb 2000 14:47:12 -0600 [alt-beam] Re: Geared motors...again beam@sgiblab.sgi.com "Paul Atkinson" Take a look at the following from MECI (www.meci.com):
#650-0671 $1.99 Gearhead motor 2 D cells (3V) and
#650-0676 $2.99 Two 30RPM gearhead motor 4 D cells (6V or possibly 3V each?)
They look like Hankscraft motors (used in moving store displays).
If I'm right, the data sheet is at:
http://www.hankscraft-motors.com/dc3440.html
Has else anyone used these yet?
Paul
Bernard Nazari wrote:
> I haven't found a motor that will work.... Any ideas? (And I did look at the MECI,
> MicroMo, and some other sites, except they don't have the roughly 30RPM@5V
> sort of motor that I want.)
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