CNET Article on Winegard's RCDT09A is the first battery-powered DTV converter box - AVS Forum
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post #1 of 14 Old 10-02-2008, 05:52 AM - Thread Starter
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I did a search here, but I didn't see that anybody has tried this yet. Is this new to us here or did I just not dig deep enough?

http://reviews.cnet.com/tv-hdtv-tune...?tag=mncol;txt
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post #2 of 14 Old 10-02-2008, 06:03 AM
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Memo to CNET - any CECB with an external power supply could be modified to be battery powered, just like this unit. Also, most small portable battery operated analog TVs don't have any inputs to make use of this CECB.

This unit probably has the guts of something we've already seen. They just make a big deal out of being able to power it with a battery pack.
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post #3 of 14 Old 10-02-2008, 06:37 AM
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It doesn't come with a battery pack either. You must purchase it separately. The battery pack isn't even mentioned in the owners manual, so you know that this "feature" was simply invented by the marketing dept. The DC input is 9 volts so you can't run it off an 12V battery without purchasing a DC-DC converter. A device that can't run directly off of 12 volts is not acceptable for RVs or in emergency situations.
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post #4 of 14 Old 10-02-2008, 07:00 AM
 
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I just use a DC-to-AC inverter to convert a 12V battery to 120 V current. Then I can use anything with a standard plug.
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post #5 of 14 Old 10-02-2008, 08:00 AM
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Quote:
Originally Posted by electrictroy View Post

I just use a DC-to-AC inverter to convert a 12V battery to 120 V current. Then I can use anything with a standard plug.

Doing that does work but you are drastically reducing the amount of use you will get from a battery in doing that which wouldn't be what you would want to do in an emergency, which is listed as a feature for this device. Using DC to power a DC device is way more efficient.

Also using a DC powered TV is more efficient because it is a smaller tv. You won't get a lot of viewing time on a 25" CRT tv from a 12V auto starter battery which what most people will commonly have to feed an inverter. A DC powered TV and a CECB with DC power (even using a DC to DC converter if not 12V) will give much longer use in emergencies.
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post #6 of 14 Old 02-23-2009, 12:42 PM
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Did anyone ever conclude that this is a negative ground unit (@9V)?

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post #7 of 14 Old 02-23-2009, 01:47 PM
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9V from 12V is easy enough without an inverter; a simple DC/DC converter will work. I have a cord intended to power a laptop which would likely work; it can go from 9V to 19V, IIRC.

I've seen battery powered analog TVs with composite input (I think I even have one with a 3" LCD somewhere, in fact) so that's not out of the question.
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post #8 of 14 Old 02-23-2009, 02:07 PM
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Yes, 9-12V is an easy thing. But if not 12V negative ground it will fry when the coax's shield is connected to a negative ground TV/System.

Even though I started a 12V thread a while back as a common topic. No one seemed willing to pull out their meter and test units for a comman database of what will work or fry.

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post #9 of 14 Old 02-23-2009, 02:52 PM
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Quote:
Originally Posted by WeThePeople View Post

Yes, 9-12V is an easy thing. But if not 12V negative ground it will fry when the coax's shield is connected to a negative ground TV/System.

Even though I started a 12V thread a while back as a common topic. No one seemed willing to pull out their meter and test units for a comman database of what will work or fry.

there are dc/dc converters that have a polarity switch selector
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post #10 of 14 Old 02-23-2009, 03:11 PM
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I'm wondering what the tolerance is on the 9v input for the Winegard CECB. Obviously, the voltage from the battery pack will drop as the box is used.
itsthemultipath is using a NiMh AA pack for his Sansonic FT300 (5VDC). The unit acts up when the battery voltage drops.
As far as 12VDC boxes go, even if the jack says 12VDC it might not be a good idea to use it powered by the vehicle battery because the voltage will vary a lot depending on whether the vehicle is running or not; it can go from 12v to 14.5.
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Even though I started a 12V thread a while back as a common topic. No one seemed willing to pull out their meter and test units for a comman database of what will work or fry.

WeThePeople: I pulled out my meter:
I made some measurements on the AC adapter for my 8" Audiovox TV that has a 12 VDC input jack and comes with an AC adapter, but no car cord. I measured the output of the AC adapter (which appears to be a switchmode PS) using my Fluke 25 DMM: OFF & STANDBY 12.02v @ 0.04A; ON 11.91v @ 0.76A. The DC jack is 5.5mm x 2.5mm (Radio Shack size N)neg.gnd:
http://www.avsforum.com/avs-vb/showt...7#post13579127 post 16
(My compass instructor in basic training used to say: "When in doubt, whip it out.")

I'm presently using an inverter (Exeltech XP125), but am working on a voltage regulated battery pack.

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post #11 of 14 Old 02-24-2009, 12:34 PM
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Quote:
Originally Posted by rabbit73 View Post

The DC jack is 5.5mm x 2.5mm (Radio Shack size N)neg.gnd.

By that you seem to be indicating that the collar is negative and the pin is positive on that plug.

Can you pull that plug out of that jack a little to expose the collar while maintaining contact with the jacks wiper and measure low ohms to the chassis for a direct short (Indicating negative ground) with the wal-wart unplugged?
The pin on that jack is easy to tag with a meter probe, but the collar wiper can be a bit tight as you know.

And yes, a regulator is strongly advised for any electronics near any alternator. Somthing simple like the three pin TO-200 cased LM7812 12-Volt regulator chip (Radio Shack Cat# 276-1771) on a small heatsink or aluminum plate. The minimum input voltage across the 78xx series needs to be 2-Volts or 14.0-Volts DC minimum though. My experience with the clones is more like 2.5-Volts, input. So this might work with the alternator online, but not after you turn off the engine.

I'm looking for a 9-Volt CECB to use a 7809 9-Volt regulator IC on. That would work fine on my huge 8D battery bank I already have for my houses 10-KW inverter rack down to 11-Volts or so.
Would work in auto's/camper's too without charger/alternator online.

Or maybe a 5-Volt CECB if there are any worth a bean...



Then there's power outages in house applications.

Three sealed 6-Volt batteries (Available at even walmart for Kids toy cars, etc.) would run this box for a good week. And 18-Volt wal-warts / power-bricks aren't that hard to find for a few dollars on eBay...

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post #12 of 14 Old 02-24-2009, 01:25 PM
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Quote:
Originally Posted by johnpost View Post

there are dc/dc converters that have a polarity switch selector

Good suggestion. Although not practical for higher loads due to ineffeciency/cost, one appropriately sized for a mere CECB would be small and inexpensive. if you are already stuck with a positive ground TV in your camper already, that might do.

Those small inverters perform the same task though (as long as they don't have the bleeder resistor from the neutral lead to the negative 12-Volt input buss like some do).

However both these decrease runtime due to waste converting. Dropping voltage across a regulator to a less than 12-Volt box seems ideal here.

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post #13 of 14 Old 02-24-2009, 01:51 PM
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The Venturer CECB sold at Target stores is the same as the Weingard. It also can use a battery pack - I've tried using the Weingard battery Pack with it and it runs great.
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post #14 of 14 Old 03-01-2009, 09:43 PM
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Quote:
Originally Posted by WeThePeople View Post

By that you seem to be indicating that the collar is negative and the pin is positive on that plug.

Can you pull that plug out of that jack a little to expose the collar while maintaining contact with the jacks wiper and measure low ohms to the chassis for a direct short (Indicating negative ground) with the wal-wart unplugged?
The pin on that jack is easy to tag with a meter probe, but the collar wiper can be a bit tight as you know.

Yes, that is what I am indicating. I moved the rest of my answer to the motorhome thread that you also frequent. It seems to be more on-topic there than here:
http://www.avsforum.com/avs-vb/showt...1#post15947101 post #15

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