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Same battery for mount and dew system?

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#76 psandelle

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Posted 23 November 2012 - 08:50 PM

Here's a quick bad shot. The black boxes (not fixed to the battery box yet) are the spike filters. The PowerPole splitter is in front. There's a cigarette lighter plug for emergencies (someone's battery at a star party dies, etc.) and for testing out new gear before PowerPole-ing it.

So far, so good,

Paul

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#77 Lord Beowulf

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Posted 23 November 2012 - 11:19 PM

Looking good!

Beo

#78 n1wvet

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Posted 24 November 2012 - 02:15 AM

Hi psandelle, maybe I missed it - could you post info on the filters? I my add a set of these to my rig as well. Also, the Power Poles work well. (looks like we used the same size) The power poles provide good peace of mind that I can't plug thinks in backwards in the dark. They only go together one way, red to red, blk to blk.

#79 MikeML

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Posted 24 November 2012 - 07:57 AM

No discussion on ground loops? Only way to be sure is to isolate the DC supply. That said, never had a problem with the dew controller.

#80 psandelle

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Posted 24 November 2012 - 11:41 AM

Courtesy of salientbunny above:
http://www.translect...?partno=SM480-8

I got them for $16 at auction (some still there, probably). PowerPoles are like Legos, and I can change rigs and wiring with ease. Great contacts, too, so I never worry about sporadic power. Also, "almost" everything takes a 2.1mm, or 2.5mm plug, so I can build power connectors easily.

Mike: okay, tell me about ground loops and what I can do about them...sigh. Next, I'll get a lightning rod and then build a house around it, and then build an observatory, and then plug into the wall.....

By the way, I'm sure there are lots of places to get PowerPoles, but the PowerWerx company are very helpful - great people, and send it out quickly.

Paul

#81 MikeML

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Posted 24 November 2012 - 01:43 PM

Paul:
http://s.eeweb.com/a...-1329780807.pdf
The easiest way to avoid them is run everything through it's own power supply whether it's own battery or AC to DC converter.

#82 HunterofPhotons

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Posted 24 November 2012 - 03:04 PM

...The easiest way to avoid them is run everything through it's own power supply whether it's own battery or AC to DC converter.


I'm not sure what you're trying to say, but the way to avoid ground loops is that everything, especially your sensitive equipment, should share a common ground. Differing grounds of differing potentials are the source of ground loops.
Dew systems with their constant heavy switching are usually put on a different power supply to avoid interference.

dan k.

#83 orion61

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Posted 24 November 2012 - 03:12 PM

Everybody is safe, I use 1 battery for both, so if there is one failure per 1000 people, MINE will Fail, so you are all good to go.
Insurance companys lock their doors when they see me coming,
When I call, as soon as they hear my voice I hear,
" No Habla English"
People on Suicide watch hang around me.
You can tell it is me coming, by the Black Cloud hovering above my head, and the burn marks on my Hat and shoes from the lightning strikes. !@#$% :throwveg:

#84 psandelle

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Posted 24 November 2012 - 03:39 PM

So, should these noise filters I have help with the ground loop problem? If not, what do I put where?

orion61 - thanks, man! I appreciate that. It's good to have a super power. Mine is: any line I get into will become the slowest line. I have data culled over decades. One line could have a hundred people, and mine will have one, my teller/cashier will have a fit and 911 will be called. Never fails.

Paul

#85 MikeML

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Posted 24 November 2012 - 03:43 PM

Differing grounds of differing potentials are the source of ground loops.

dan k.


Yes they are.
The common ground or neutral is the path for the ground loop.

#86 Pauls72

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Posted 24 November 2012 - 05:05 PM

Cigarette lighter adapters and splitters are notoriously poor quality connections. You are better using either ring or spade connectors or other types of sockets/plugs. The second problem with the Cigarette lighter splitters is that the wire from the plug to the splitter is usually a fairly small gauge and not up to carrying a lot of current. Which means you will have voltage drop across the wire and maybe a potential fire hazard if the wire gets hot.

My background is in electronics and I use one battery to power my Atlas mount, dew heaters, and my SBIG camera all at the same time. A large auto/marine type battery is a great filter in itself. As long as you use heavy enough gauge wire and connectors back to the battery you should be OK. You just need to stop before the battery voltage gets too low to prevent damage to the battery.

Lord Beowulf's test while looking impressive really isn't. That 37V pulse looks to be only 100 nano seconds wide (0.0000001 seconds). That can easily be taken care of by a by a small filter capacitor. Yes, your mount, camera and most electronics and at least a minimal amount of power filtering. Sorry I don't have have a digital storage scope, only an old analog one, so I have no way of capturing screen shots of short events. But if Lord Beowulf puts his oscilloscope across the terminals right on the battery and re-performs the test the pulse will only be a small fraction of the amplitude that it is in his experimenter.

You are probably way more likely to blow something up with electronics in it (including your mount or hand controller) from static in your house during winter. A static discharged is in the thousands of volts. It takes about 25K Volts to jump 1 inch, so even the 1/4 inch spark around 6K Volts.

If you are paranoid you can buy or build a filter assembly for each device. But first I would chuck out all the cigarette lighter adapters.

#87 thesubwaypusher

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Posted 24 November 2012 - 10:40 PM

Well, I don't know what Dr. Clay is a doctor of, but my guess is that it is not Electronic Engineering.

So dude, if Dr Clay scared you, I am sorry to hear that, but my experiecne and my electronic background both say that this myth is busted.

I do not know what DR. Clay is a doctor of, but as an electronics engineer, I would say that however he came by this position, it is in error.

And how much wire would be required to produce an inductance required to triple the input DC voltage?

6000 ft?



You're just too funny. :roflmao:

#88 n1wvet

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Posted 25 November 2012 - 02:00 AM

Thanks Paul, agree on the interchangability. I use Power Poles on both batteries, both scopes, kybd lighting (red) and dew controller. Everything is compatible.

#89 Pauls72

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Posted 25 November 2012 - 02:02 AM

Dew Controller, I had it hooked up my 14amp hour battery with 2 dew straps output port 1 11"-9 ohm;, port 2 2"-48 ohm; and ports 3 and 4 using 1K ohm; load resisters. I changed my dew controller program to switch all 4 outputs on/off together at 80% duty cycle.

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Basic Schematic of the dew controller.

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Point #1, About an 11V swing as this is the on/off to the dew strap it is expected. Scope is set to 2 Volts/CM and zero volts is set to the bottom line. Yes, I know the trace on my scope is slightly crooked.

Posted Image


Point #2 This if the 12V buss/supply to the output ports (dew straps) right at the connectors. There is less the 1/2 volt ripple at this point.

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Point #3, this is the 12V input to the dew controller. It is flat line DC.

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#90 teskridg

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Posted 21 December 2012 - 06:03 PM

"My observing philosophy: Find out what it is that your telescope doesn't do well, then don't do those things."

Jim: this may be the smartest single sentence I've read on these fora. Thank you! Tim

#91 Ronnie Miller

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Posted 27 December 2012 - 01:11 PM

Can someone tell me how these filters will stop the voltage spikes? The filter input range is from 4 to 60 volts and if the spikes are around 40 volts, would it not let them pass through to your equipment? Or does is suppress anything other than the nominal input voltage applied at the source?

#92 Pauls72

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Posted 27 December 2012 - 02:08 PM

The simplest explication is to think of filters as surge suppressors.
Voltage spikes are of a very short duration, so this effectively makes them a very high frequency pulse and makes them very easy to get rid of. The energy from the voltage spike can either be dumped to ground or averaged out over a long period of time depending on the design of the filter.

You will end up with something like this:

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