Re: [PSUBS-MAILIST] link

[Ian Roxborough <irox@ix.netcom.com>]

You are going to get a lot of power loss convert to DC to AC and back 
to DC again.  Although, for a wetsub, with the dive time limit by the
human ability (i.e. decompression tables/dive times), the reduced
operation time due to power loss might not be a big deal.

Another downside is that this adds more components that could fail
or need replaced at some point.  The three components (DC-to-AC
converter, dimmer switch, and the AC-to-DC converter) could be
replaced a DC pulse-width-modulator (PWM).  I'm not sure if what
you're looking for avaliable in a 'off the shelf' solution, but
I seem to recall plans for a PWM motor controller are some where
on the psubs website (I don't have the link for it though).

Ian.

On Wed, 8 Feb 2006 04:04:41 -0500
"Akins" <lakins1@tampabay.rr.com> wrote:

> Hi again Norm.
> 
> I just realized another possibility Norm. I could locate BOTH voltage converters in my battery pod. One for coming from the batteries to the dimmer switch, and another also located in the battery pod
> going from the dimmer switch to the motor. Could work, but I'm still looking for something with less bulk and pieces.
> Thanks once again though for the idea and the links.
> Bill Akins.
> 
> 
> 
>   ----- Original Message ----- 
>   From: Akins 
>   To: personal_submersibles@psubs.org 
>   Sent: Wednesday, February 08, 2006 3:41 AM
>   Subject: Re: [PSUBS-MAILIST] link
> 
> 
>   Hi Norm.
> 
>   Hmmmm. An interesting possibility converting it to ac. However I would then have to reconvert it back to dc again. You see, my wiring will come from my battery pod on the keel
>   up thu the sub and into my cockpit where it would go into the pvc pipe I would use to house the dimmer switch and inverrter you speak of. Then it has to go from my dimmer switch
>   to the motor. So in order to convert from dc to ac going into the dimmer switch as you described, I would also have to reconvert it back to dc after it left the dimmer switch going to the motor.
>   That now makes an inverter for dc to ac, then a inverter from ac to dc, plus the dimmer switch itself. Quite a lot of bulk to fit inside the pvc pipe that I was hoping to keep as small as possible.
>   Of course I could put the first inverter in the battery pod with the batteries so that the dc coming from the batteries was converted to ac before it even left the pod. But I would still have to have 
>   another inverter for ac to dc either enclosed in pvc with the dimmer switch, or else enclosed in another waterproof/pressureproof container before the electricity reached the motor.
>   Thanks for the idea though. Sounds like if I used one for dc to ac and then one for ac to dc it might work.  But I hope I can find something less bulky.
>   Bill Akins.
> 
> 
> 
>     ----- Original Message ----- 
>     From: Norm Parmley 
>     To: personal_submersibles@psubs.org 
>     Sent: Tuesday, February 07, 2006 5:51 PM
>     Subject: Re: [PSUBS-MAILIST] link
> 
> 
>     Bill,
>     One of the easy ways is buy an inverter,  (DC to AC)  and then use the dimmer switch.  However, remember power concerns, size the inverter and dimmer switch for your load/loads....ie motor/motors max load.  You'll still have to make them water proof.
>     Here are some links: http://www.donrowe.com/inverters/inverters.html?src=overture , http://www.apc.com/products/family/index.cfm?id=13&tab=features plus you can find them at Wal-Mart, and auto parts dealers.
>     Hope this helped.
> 
>     Norm P.
> 



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