Re: More thoughts and observations regarding power supplies


fl.lusen
 

Woody,

Do a google search on DC to DC converters.  You can get them to go from 12vDC to most anything.  It will also serve to isolate your camera from everything else that is on the 12v supply.

Fred

-----Original Message-----
From: 'Woody Schlom' woody@... [ap-gto]
To: A-P GOTO Mounts Yahoo Group
Sent: Tue, Oct 31, 2017 11:40 pm
Subject: [ap-gto] More thoughts and observations regarding power supplies

 
As some of you have already read, I sent my "bad" power supply to
Christopher in Hawaii and it tested OK for him. He said it's quite
warm, but otherwise OK. But I'm done with that one. It's already
ruined too many things for me.

And I'm not even sure I like it's older brother currently in my mobile
observatory -- even though that one has been working perfectly for
several years now. One of my problems with that particular brand and
model is the fact that there's no cooling fan. I like the silence and
simplicity, but I do a lot of solar observing in the Southern California
deserts and things can get quite warm just from ambient temperatures.
So I'm in the middle of re-powering both the mobile observatory as well
as my portable systems.

And thanks to the previous discussions here and research I've been doing
on my own, I've learned some "interesting" things regarding power
supplies.

1) I now have one of Powerwerx's variable power supplies. I like it so
far. It's small and seems to do what it's supposed to do. HOWEVER --
there's at least one potentially serious problem using it with a certain
camera.

2) My imaging camera is a QSI-683m/WSG/8. And similar to most astro
cameras, the power socket says "12v DC." No big deal, they almost all
say that. But since the Powerwerx power supplies put out 14.1v DC in
their "fixed" mode, I wanted to make sure the QSI was OK with that
voltage. Well, apparently NOT!

I don't usually trust or believe most of what's on Cloudy Nights, but
there's a thread discussing this very issue. And more than one poster
quoted a guy named "Dave" at QSI strongly recommending 12v DC ONLY! One
person even re-printed one of Dave's Emails regarding the question.
According to QSI's "Dave", the absolute upper voltage limit for the QSI
cameras is 14.0v. He said 13.8 is theoretically OK, but too close for
his comfort. And although he didn't say so, I assume 14.1v would void
the warranty.

But the even more interesting thing he said was that at voltages above
12v, the camera can't/doesn't cool as well -- because it's trying to
dissipate heat from the additional input voltage in addition to cooling
the camera. He recommends using the supplied QSI AC to 12v DC regulated
PS -- or inserting a regulated 12v to 12v DC PS between the camera and
any other nominal 12v source. This is for voltage regulation as well as
potential ground loop problems.

I tested my supplied QSI AC to DC regulated power supply and it's
putting out 12.30v with no-load.

Dave gave a link to a regulated 12v to 12v PS he approves of and it's
just a PC board -- with screw terminals -- for either $75 for the 25w
version or close to $90 for the 50w version. I can see why it's
probably a lot simpler and cheaper to go with the supplied QSI PS.

So I can use my new Powerwerx PS with my QSI camera, but I'll need to
crank down the output voltage to somewhere between 12.0 and 12.3v.

I'm sure glad I learned this BEFORE plugging 14.1v into my RIGrunner and
powering the camera from it -- which was my original plan.

3) And this brings me to the subject of RIGrunners. I have and use two
of them -- both 4005 models. A different "Dave" who is on this group,
mentioned that his RIGrunners which are controlled by USB, show a slight
voltage drop. This surprised me as I thought mine were passive. So I
tested one of my 4005 models. The PS I used was putting out 13.81v DC.
I got 13.81v at the input side of the 4005 and 13.81v at each of the
outputs. Whew. I'm not nuts. The 4005 really is passive. Apparently
it's just the fancier RIGrunners with internal circuits that slightly
drop voltage.

4) When I realized that my "new" PS was blowing things up and melting DC
cables, I ordered a new PS (different brand). Based on nothing more
than size, weight, the fact that it has two built-in PP sockets, an
adjustable "noise reduction" pot, a meter that shows voltage or
amperage, and the published specs., I purchased a TekPower TP30SWI.

This afternoon I conducted a few more tests on it. It works and I can't
find anything wrong with it. However, I don't like it because the fan
runs all the time. Granted, with no or low loads, the fan runs very
slowly. But I can still hear it -- and I don't like it. Some of my
uses are for public outreach where I need to listen and talk to the
public. And I don't like talking over fans. I already have to talk
over the fan in my old video PROCAMP and that's enough.

And the other problem I never anticipated with this PS is the analog
meter light. It's always ON. And it's WHITE!!!

So for those two reasons, I won't recommend this PS to anyone else.

5) I still haven't heard from Optec or MallinCam regarding operating
their equipment on 14.1v, but after learning about the QSI not wanting
14.1v, I'm now on my guard more than ever.

Woody

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