Re: Re: [PSUBS-MAILIST] RimTec Magnetic Clutches

[<drewacard@charter.net>]

How about 
http://www.newark.com/NewarkWebCommerce/newark/en_US/endecaSearch/partDetail.jsp;jsessionid=5ZI5JED0CCQFOCXFEOFCFFYK2URYWIV1?SKU=02F1135&N=0

100Amp 400A peek
18 volts dc
Cost $50 + shipping

They also have other ratings and electronic relays ?no mechanical contacts?

Andy

From: Paul Kreemer <paulkreemer@gmail.com>
Date: 2005/10/24 Mon PM 12:12:48 CDT
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] RimTec Magnetic Clutches

Bill,

I'd say a couple of reasons for using relays are to minimize the size of
your control switches and shorten the length of your high current electrical
lines. A bonus reason would be to keep that high current away from the
operator! Here's a Minnkota FAQ page that helps you estimate wire size or
gauge for their motors.
http://www.minnkotamotors.com/support/faq.asp

They work through a short example of 20ft of wire and a 37amp draw and
recommend a 6awg wire which is about a sixth of an inch in diameter. So as
your amperage and wire sizes increase I think you start to look more and
more at controlling it remotely with a relay.

But like you say, you have a different situation where you don't want just
an on-off control for your motors. A relay, as I understand it, is just an
on-off remote switch. It sounds like you want a pulse width modulation motor
controller to get good smooth control and more efficiency out of your
battery/motor combo. Minnkota calls it their Maximizer and here's another
link that discusses a custom built PWM control for a robot:
http://www.robotwars.ecs.soton.ac.uk/file/pwm_motor_control.html

But after all these notes, I have no comments on immersing the whole thing
in a wet sub. :-)


Paul






On 10/24/05, Akins <lakins1@tampabay.rr.com> wrote:
>
> Hi Byron.
>  I have a completely wet, dual cockpits, wetsub Byron, it isn't ambient. I
> already have my minnkota mounted to the hull using
>  a motor mount I made from an old stop sign I cut and bent. If you would
> like to see my sub's set up you have to belong to yahoo because the
>  pictures are at my yahoo group site at this link....
> http://groups.yahoo.com/group/The_Warbird_Recovery_Team/ once you get
> there and sign in to yahoo,
>  just click on the "photos" section on the left of the page in the yellow
> column and the album is the first one called "my two person wetsub".
>  Thanks for the info on the hydraulic thrusters but I've already got my
> minnkota motor mounted. I just need to decide whether to oil or air equalize
> it.
>  Right now I am on the hunt for magnetic variable speed reed switches to
> activate the relay to the motor. One thing I am wondering
>  about is WHY do I even need a relay solenoid? Why couldn't I just wire it
> direct from the battery to the switch and then to the motor? Does it have
>  something to do with too high a voltage or amps going thru the switch and
> that is not good or something like that? I'm not real good at the
>  electrical stuff. Also I am wondering how a magnetic switch could
> possibly be variable if it just clicked in a solenoid relay?
>  As you suggested I have talked to some of the ROV guys. I am a member of
> the yahoo group called "Robotrov" at this link......
>  http://groups.yahoo.com/group/robotrov/?yguid=204005530 which is a group for
> robotics and ROV's. Unfortunately even though one of them
>  responded to my post at the group, his link and info did not lead me to
> switches I need. His link sent me to a site with electronic circuit boards
>  that would be used inside a sealed unit in a ROV for instance. I need
> something small and compact that I can use either in the cockpit or attached
>  to the joystick in my wetsub. I thought about using a mercury switch and
> rigging it so that I could just turn it to make contact. If the attitude
> of my
>  sub was always horizontal that wouldn't be a problem but if things got a
> bit murky underwater and the sub was not horizontal and I got disoriented
> the mercury
>  switch might make contact when I did not want it to. So I decided to not
> use it and to continue to try and locate the magnetic reed switches.
>  Ideally I would like to find a magnetic reed switch that was already
> waterproof and sealed, but if I can't find one waterproofed, I could rig it
> up in
>  a real small piece of pvc pipe I guess.
>  Bill.
>
> ----- Original Message -----
> *From:* Byron Selman <byron@flyingfishfoto.com>
> *To:* personal_submersibles@psubs.org
> *Sent:* Monday, October 24, 2005 5:57 AM
> *Subject:* Re: [PSUBS-MAILIST] RimTec Magnetic Clutches
>
> Have you thought of talking to some of the thruster guys? All of the ROV's
> out there ( except el-cheapo cheapo toys) have some external thrusters. They
> are almost always electric. I worked for Deep Sea Systems, Inc. as a
> consultant for about six months, and have been friends with Chris Nicholson
> (owner/pres) for twenty years. If you can catch Chris's imagination, he can
> be a world of help. He builds and sells electric thrusters.
>  Innovatum is another group.
>  Slightly different subject, but I gotta ask:
>  Have you considered hydraulic thruster motors? You keep the pump inside
> the sub and use through-hull fittings to run hydraulic motors outside.
> Putting a piece of pipe fitting through a sub wall for hydraulic hoses is
> lots easier than either electric feed-throughs or a shaftdrive with a
> stuffing gland.
>  Or bite the bullet, use the stuffing gland or o-rings on the spinning
> motor shaft, design for drips and put a small bilge pump under it venting
> overboard. Need a good check valve and a stout pump for ambient, but its
> doable.
>
>





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