Re: Bag Power Distribution

Hi Paul,
Since caps are one more thing to go wrong, I would use them as
necessary, only. If it ain't broke, don't screw with it. If the audio
from a particular unit has whine, add a cap to its line. If you can
determine the other part of the pair that is causing the whine
(connect and disconnect devices) add a cap to it also.

As far as your second question, I know some distribution systems use a
polyfuse on each output. That way one shorted line doesn't take down
the entire system as a single fuse will do. I personally think a
inline fuse for each power run is a good idea. These fuses can be
larger than what the device needs for current; the fuse is there to
protect against red hot wires and burning bags. Specifically, a 5 Amp
polyfuse can be used with #18 wire even if the device (UCR411) only
pulls 0.2 Amp (200 mA). The 411 has its own internal fuse; you are
trying to protect the #18 gauge wire. Some other advantages to some
distribution systems are switched outputs, a switched main power, and
power output jacks so gear can be quickly disconnected.

If you have simple distribution system, a main fuse is still a good
idea. If you have a short, a complete shutdown may still be the lesser
of much fire and brimstone. The main fuse has to be small enough to
protect your smallest cable yet large enough to power all the gear
even when it is hot outside. All thermal fuses open more quickly in a
hot environment, particularly polyfuses.

Best Regards,
Larry Fisher
Lectrosonics

On Mon, 26 Nov 2007 10:12:03 -0800 (PST), Paul Graff
<ahomeforspamonly@xxxxxxxxx> wrote:

Thanks Larry! Well, first of all, all of the "other equipment plugged
into the same battery" is Lectrosonics and Sound Devices, so I'm off
to a good start there. I am convinced this is a prudent idea,
however, and I will install these caps on all my rigs over the
holidays.

For IFB, I've recently gone from UM400's in IFB mode (battery-
powered), to a IFB T1 in one rig and a T4 in another, which are, of
course, DC-powered. Would you also recommend a 3300uF 16V cap 1inch
from TX DC plug?

Sometimes I wonder if I'm just being cheap with my straightforward
power distribution system. In your opinion (or anyone else's), are
there significant advantages (other than convenience) to using a Hawk-
Woods or BDS system? They struck me as unnecessarily bulky and
expensive, but most folks use them. As far as I can tell, those
systems would not eliminate the need for the modification we're
talking about in this thread, right? BDS info says it has a 6amp
circuit breaker, but no other protection is mentioned.

Regards,
Paul


.

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