Alt-BEAM Archive
Message #11099
To: beam@sgiblab.sgi.com
From: "Sathe Dilip" sathe_dilip@bah.com
Date: Tue, 29 Feb 2000 11:43:50 -0500
Subject: [alt-beam] Re: mini walker
Richard Piotter wrote:
>
> Is there a way to focus the magnetic field to a smaller area, yet not be
> attracted to a magnet when no power is applied. I assume that's what
> iron cores are for, but the tiny magnets I'm using are very powerful,
> and they stick to the iron cores. is there a special type of core I
> should use, or can I use one of those ferite cores? Can ferite cores be
> cut? I know they chip. The magnets are 1/4 inch diameter,
SNIP
To concentrate magnetic lines of force (focus as you say) in a certain
area, you have to use magnetic material as a core (on which to wind the
coil). Unfortunately, you will also end up with an electromagnet to
which your other permanent magnet will stick when not energized (so as
to repel). Other problem with some core materials is the property of
retentivity. This means the core will retain some of the magnetization
from previous energization. So even other magnetic materials will stick
to your electromagnet (though weakly) even when not energized. You can
overcome some of this by using a non magnetic pole piece. Attach a thin
disk of say plastic to the core end. But this will reduce the kick/pull
to some extent.
Come to think of it, you can probably use the retentivity to your
advantage in applications like the magbot (needing only the repulsion).
Once you repel the magnet, the retained magnetism will act to cancel or
atleast reduce some of the sticking force.
> I'm sending a picture to show how small it is. All I need are 2 "major
> henry" strenth coils. I'm going to see what kind of speaker wire is
> avaliable localy and wind my own coil. I'll have to dig up my text books
> from last year. Figure out the best possible coil configuration.
SNIP
Speaker wire (if you mean the wire used to connect speakers in a system)
is not a good choice. The insulation takes up a lot of space. Ideal is
enameled copper wire. You could try Radio Shack part # 278 - 1345 which
gives you magnet wire in 3 gauges. The three sizes will allow you to
experiment as dave says.
Dilip
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The early bird may get the worm, but the second mouse gets the cheese.
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11100 Tue, 29 Feb 2000 11:59:55 -0500 [alt-beam] Re: Voltage Multiplication beam@sgiblab.sgi.com "Sathe Dilip" Linear technology used to make some chips that allowed using a single
pencil cell (1.5 volts) to power some circuits at 5 volts.
I am not sure to what discharge voltage it permitted operating the
circuit. If it allowed working down to 1 volt, you could try that.
There are probably other manufacturers there who have similar devices.
One problem with silicon devices is that at these smaller voltages,
their BE & CE voltage drops become a significant loss thus giving you
low efficiency numbers.
http://www.linear.com/
Dilip
-----
Andrew Hooper wrote:
>
> Im using some low voltage high current solar panels
> thay are rated at 1volt 250ma and work prety well
> however there is little that can be done with 1 volt
> and connecting multiple cells up in this case is not
> an option.
>
> Has anyone managed to built a voltage multiplication
> circut?
----------------------------------------------------------------------
The early bird may get the worm, but the second mouse gets the cheese.
----------------------------------------------------------------------
11101 Tue, 29 Feb 2000 09:35:31 -0500 Re: Diskette Drives/camera parts Zane Bryan
> Occasionally I've come across solenoids, but until the recent thread on
the
> little "hoppy bot" I hadn't given them much thought. Saw someone talking
> about geared motors from lens assemblies for around 30 dollars...I have
six
> from free cameras...a MUCH better bargain, don't you think? I've a few
gear
> assemblies as well...
>
> Z
>
>
> ----- Original Message -----
> From:
> To:
> Sent: Monday, February 28, 2000 4:56 PM
> Subject: Re: Diskette Drives/camera parts
>
>
> > that is awesome, that must be why i love BEAM, cause i'm a damn cheap
> skate!
> > Have you ever found any solenoids in that bunch?
> >
> > -Spencer
> >
>
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