TV with 14v brick, okay at 12.x volts?

wa8yxm wrote:
That is true, I have the same problem when I use my Cell phone to feed the AUX-IN on either my motor home or the car..

now in the case of the car, there is no direct electrical connection so I know it's not a ground loop, but on the MH, could be.. Hey, thanks for making me think of that, I may be able to FIX the car. (Common mode I can kill).

I also have that same issue when I run my Ham Radio using my compter and the direct DC/DC converter for the compuer.. No problem when I use the 120 volt and fully isolate.

If you are using a car charger at the same time then you WILL experience a ground loop problem.

Not all car chargers break the ground...

I would suggest trying to insert a ground loop isolator between the cell phone and radio input jack..

Snowman9000 wrote:
I found that I get an interference signal when feeding the DVD signal from the dash head unit to the TV, when the TV is directly powered by 12v. The interference goes away when I power the TV from 110v thru its brick. The brick 14v output cable has a small wart on it to do some kind of filtering or noise prevention. My homemade cig plug cable does not.

The TV works perfectly otherwise. The DVD is fed through low quality red/white/yellow AV cables. But as I say, it comes through fine when the TV is powered by its brick.

We hardly ever play DVDs,
We could power the TV by brick when we want to play a DVD,
Including by inverter if need be.

But I'm curious as to the problem.

It is known as a "ground loop".

Basically it happens when you have several DIFFERENT "grounding" points between devices.

Your DVD player is grounded in one place in the wiring harness and your TV is grounded in a DIFFERENT place. Connecting the video and audio grounds from the DVD to TV creates a "short cut" DC path between the two different grounds.

This creates very small current flow on the ground wire (AKA "shield") of the A/V cables. These currents makes the TV see "noise" on the grounds and the result ends up on the TV screen (lines or interference) and also the audio as a hum/buzz.

Using the AC power brick breaks or isolates the ground of the TV stopping the interference.

To get around the ground loops you need special isolation transformers for the video AN the audio.

THIS is an example of a VIDEO ground loop isolation transformer.

THIS is an example of a AUDIO ground loop isolator.

You WILL need BOTH to fix you problem...

That is true, I have the same problem when I use my Cell phone to feed the AUX-IN on either my motor home or the car..

now in the case of the car, there is no direct electrical connection so I know it's not a ground loop, but on the MH, could be.. Hey, thanks for making me think of that, I may be able to FIX the car. (Common mode I can kill).

I also have that same issue when I run my Ham Radio using my compter and the direct DC/DC converter for the compuer.. No problem when I use the 120 volt and fully isolate.

I found that I get an interference signal when feeding the DVD signal from the dash head unit to the TV, when the TV is directly powered by 12v. The interference goes away when I power the TV from 110v thru its brick. The brick 14v output cable has a small wart on it to do some kind of filtering or noise prevention. My homemade cig plug cable does not.

The TV works perfectly otherwise. The DVD is fed through low quality red/white/yellow AV cables. But as I say, it comes through fine when the TV is powered by its brick.

We hardly ever play DVDs,
We could power the TV by brick when we want to play a DVD,
Including by inverter if need be.

But I'm curious as to the problem.

Gdetrailer wrote:


A 12V lead acid battery fully charged and at rest is nominally 12.8V, not 13.6V.

Yup, absolutely right, 13.6 is the FLOAT voltage, not the resting voltage, Look it up in your converter owner's manual.

Snowman9000 wrote:
Well, for those who are looking, it seems the Samsung UN19F4000 (19") and UN22F5000 (22") run off a 14v brick. The former typically consumes 15w at 120v, and the latter consumes 18w. The 22" is cheaper ($149) than the 19" ($160), and is 1080p. The 19 is only 720p. I think the 22 is going to be on my Xmas list.

To report back on this, the Samsung un22f5000 has worked flawlessly plugged direct to DC, even below 12v, when other items were dragging the batteries down. The AC/DC brick that came with it puts out 14.4.

Also, the picture and viewing angles are very good.

I agree with Roy and Paul, I ran a 13" CRT tv on 12 VDC to, never any problem. I now have two 19" flat panels and my Blu Ray player direct to 12VDC.

Mine are Insignia and Dynex BR is Dynex. Available at Best Buy.

wa8yxm wrote:
I will say this, your 12.x is normally 13.6 which is in the range of 14+/-10% and thus it shoudl work fine most of the time.

It will likely work all the time (12 is 14+/- less than 20 perecent, Most electronics can take a 20 percent "off" power supply, KEY WORD, Most.)

:h

A 12V lead acid battery fully charged and at rest is nominally 12.8V, not 13.6V.

13.6V typically is when you are RUNNING an auto engine and the alternator is attempting to CHARGE the battery. Actually in reality your auto alternator is SUPPOSED to be set to 13.8V or slightly higher.

Typically in a RV your house battery when at rest will have 12.8V, when the converter is charging it will be 13.2V up to 14.4 depending on what "mode" the charger is in.

"Most" HOME electronics DO NOT appreciate voltage swings of +/- 20% and will let out the smoke packets if you attempt to use a voltage source that far out of range. 20% of 14V is 2.8V which would be 11.2-16.8 which will be way out of the typical HOME type appliance.

If you were talking about purpose made "auto" 12V items like car stereos or even Ham radio equipment you would be with in the realm of possibility. Those devices ARE designed around the auto electrical system.

One must understand that HOME electronic equipment which uses those "brick" power supplies are designed with TIGHTER TOLERANCES since the manufacturer is BASING the entire design around what in a sense is a computer switching power supply. By the way computer MBs are very finicky when it comes to voltage range, the acceptable voltage range on the 12V line is 11.9-12.1.

I will say this, your 12.x is normally 13.6 which is in the range of 14+/-10% and thus it shoudl work fine most of the time.

It will likely work all the time (12 is 14+/- less than 20 perecent, Most electronics can take a 20 percent "off" power supply, KEY WORD, Most.)

A 12V/14V converter should fix performance issues without the 5-20W power draw of an AC inverter. We us a switchable downconverter from Radio Shack, but there are other suppliers out there.