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Hi Ian.
Thanks for the info on the power loss. I am now
thinking that if I can't find a ready made switch for what I am looking
for,
then perhaps I could do away with needing the dc to
ac and ac to dc converters by just using a dc 24 volt pot
instead of an ac dimmer switch. That way I would
not requre conversion. Now the question is....can I find a dc 24 voIt
potentiameter?
I know I could get one off an old car radio volume
controller, but that is only 12 volt dc. I need 24 volt. I'll check with radio
shack.
I like the idea of the clear acrylic housing with
the ready made stem on the port that you just
drill a hole for and screw the stem and port into place and then attach
the
stem to the 24 volt pot's stem. If I can't find a
ready made one, this seems like a really good alternative plan. I'd have to
weight it a bit to keep it from being buoyant but
that wouldn't be a problem. I would need to install
some sort of spring on the knob though to act as a dead mans switch cutoff.
Wouldn't want to inadvertantly bump the knob
while I was outside the sub and have it run away
from me unoccupied! I could just replace the knob with a lever and install a
spring or small bungee on the lever as a dead mans
switch cutoff.
Now I am wondering if it is safe and if I should
use a system that carries 24 volts dc thoughout my entire wiring or if there is
another way
to control my motor by using a lower voltage wire
from my pot in the cockpit. I was trying to keep things simple without getting
into
a whole lot of wiring connections except for my
batteries in series and the safety fuse or breaker switch.
Bill Akins.
----- Original Message -----
Sent: Wednesday, February 08, 2006 4:58
AM
Subject: Re: [PSUBS-MAILIST] link
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="">
, 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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