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5V regulated supply

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Tim(at)MyRV10.com
Guest

Posted: Thu Mar 16, 2006 9:18 pm Post subject: 5V regulated supply

I'm looking to build/buy a simple regulated supply for my normally

AC powered Audio/Video players for in the airplane.  I could use

an inverter, and then their AC supplies, but what I'd prefer

to do is just take the 12V in, and get 5V out.   I just tried using

the 7805 3-pin T0-220 regulator from Radio Shack (was unable to use

a heatsink in the test), and one of them wouldn't push enough

current to drive one of my 2 devices.  2 of them in parallel would

drive it, but it wouldn't play through a movie.



Is there some heavier duty package that has worked well for people

in the past?  I'd like to make it portable, so I can take it in

the car.



In the end, I'll have 1 lighter plug, driving 2 LCD headrest

monitors, 1 video splitter, and 2 MP3/Video players.



One of the players had an AC supply that says 5V(at)1A, and the

other says 5V(at)2A, so I would have thought the 7805 had a

fighting chance, but I guess that's with a heatsink or something.



Tim

-- 

Tim Olson - RV-10 N104CD - Flying

do not archive

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Thu Mar 16, 2006 11:02 pm Post subject: 5V regulated supply

Tim Olson wrote:



 	  Quote: 	
		   One of the players had an AC supply that says 5V(at)1A, and the

 other says 5V(at)2A, so I would have thought the 7805 had a

 fighting chance, but I guess that's with a heatsink or something.


	


Yes. If you look around you can find 12V-in-5V-out switching supplies. 

That is what you really want.



-- 

Brian Lloyd                         361 Catterline Way

brian-yak at lloyd dot com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

- Antoine de Saint-Exupery

_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

Dan.Beadle(at)hq.inclines
Guest

Posted: Fri Mar 17, 2006 5:54 am Post subject: 5V regulated supply

With a linear regulator, you want to drop 3A from 14V to 5V. That is 9*3

or 27 Watts.  That is the heat released by a small to medium soldering

iron.



You could to it with a T0-3 package of a linear regulator (see Digikey),

but a switcher would be much more efficient.  



Assuming 80% efficiency, you would only lose about 3 watts in heat.

Your system would only draw about 1 amp from the ships power.  



You can build your own with a PCB from National Semiconductor.  Their

WorkBench lets you design the parameters you want, then buy a kit of

parts.  A kit is about $30.



Dan

--

klehman(at)albedo.net
Guest

Posted: Fri Mar 17, 2006 5:58 am Post subject: 5V regulated supply

Hi Tim

I do agree with Brian as it sounds like you will probably need several 

7805's and outlets to use them. Many folks opt for cigarette lighters 

and a 12 volt adapter if available for entertainment devices. Those 

adapters are likely linear regulators.

7805 devices are linear regulators so drawing an amp through one 

requires it to dissipate 1 amp times the voltage drop. 14 volts to 5 

volts is 9 volts times one amp or 9 watts. Twice that for 2 amps etc. So 

you definitely need a good heatsink. An aluminum airframe has lots of 

heatsink available. The TO-3 package will usually handle more current 

than the TO-220 parts but they are harder to mount. I would not 

recommend feeding 5 volts to a conventional cigarette lighter outlet 

though as sooner or later someone will plug in something that wants 12 

volts. AFAIK all  the 78xx packages have overheat protection and will 

(most of the time) shut off if overheated. They will also sometimes do 

strange things if you don't use the recommended capacitors with them. My 

vague recollection is 1 amp or so from a TO-220 part, 3 amps from a 

TO-3, and 5 amps from a larger part (LM350?).

Ken

Brian Lloyd wrote:

 	  Quote: 	

Tim Olson wrote:

>One of the players had an AC supply that says 5V(at)1A, and the

>other says 5V(at)2A, so I would have thought the 7805 had a

>fighting chance, but I guess that's with a heatsink or something.

>    

>

Yes. If you look around you can find 12V-in-5V-out switching supplies. 

That is what you really want.

Tim(at)MyRV10.com
Guest

Posted: Fri Mar 17, 2006 6:23 am Post subject: 5V regulated supply

Thanks for the suggestions, guys.   Time is a factor too as I'm

hoping to use this all on the way to Sun-N-Fun.

So far I see these as options:

http://www.powerstream.com/dda.htm

http://www.powerstream.com/mini-itx.htm

The national semiconductor kit is appealing too, although once you

get to $30 it starts to make sense to buy a completed unit if

possible



I'm starting to lean back towards just buying another inverter

to dedicate to the plane, since it would be pretty flexible

for many uses, and is something I can just grab locally.



The largest concern with this whole project, and the reason

I wanted to build it, is that I want to ensure that the power

to the video/audio box is at the same ground potential

as the plane's system.  I used a radio shack multi-output

lighter plug the other day with my old MP3 player and got

a nasty ground loop whine when I had the thing plugged in.

On batteries it was great.   My concern is that perhaps with

an inverter or with a prebuilt converter that I won't have

a common ground potential.



Thanks for the tips thus far.



Tim Olson - RV-10 N104CD - Flying

do not archive

Dan Beadle wrote:

[quote] 

 

 With a linear regulator, you want to drop 3A from 14V to 5V. That is 9*3

 or 27 Watts.  That is the heat released by a small to medium soldering

 iron.

 

 You could to it with a T0-3 package of a linear regulator (see Digikey),

 but a switcher would be much more efficient.  

 

 Assuming 80% efficiency, you would only lose about 3 watts in heat.

 Your system would only draw about 1 amp from the ships power.  

 

 You can build your own with a PCB from National Semiconductor.  Their

 WorkBench lets you design the parameters you want, then buy a kit of

 parts.  A kit is about $30.

 

 Dan

 

 

 --

klehman(at)albedo.net
Guest

Posted: Fri Mar 17, 2006 7:03 am Post subject: 5V regulated supply

Tim



That intrigues me if you really had a ground loop whine with the device 

grounded to the cig lighter plug. Was it in sync with the strobes or 

transponder? My metal cig lighter outlets are mounted on a metal 

instrument panel and I wondered if I might have to in the future 

insulate them for some devices. I thought that was unlikely as most 

everything goes to a common ground point in my machine. If you really 

have a ground loop issue then I would expect it to still be there with 

an inverter plugged into the same place although I guess extra 

components in the inverter etc. might filter the noise out.



I would not expect a problem if the entertainment devices are insulated 

from the airframe with no local grounds. ie insulate the device and run 

both power and ground wires back to the cig lighter plug. My next step 

would be to insulate the cig lighter outlet ground from the airframe if 

you think the noise is being picked up in the ground between the outlet 

and the common airframe grounding point/battery/alternator. You can get 

plastic outlets from marinas but they don't seem to retain the plug very 

well. Might be easier to filter the power I suppose.



Ken



Tim Olson wrote:



 	  Quote: 	
		  



Thanks for the suggestions, guys.   Time is a factor too as I'm

hoping to use this all on the way to Sun-N-Fun.

So far I see these as options:

http://www.powerstream.com/dda.htm

http://www.powerstream.com/mini-itx.htm

The national semiconductor kit is appealing too, although once you

get to $30 it starts to make sense to buy a completed unit if

possible



I'm starting to lean back towards just buying another inverter

to dedicate to the plane, since it would be pretty flexible

for many uses, and is something I can just grab locally.



The largest concern with this whole project, and the reason

I wanted to build it, is that I want to ensure that the power

to the video/audio box is at the same ground potential

as the plane's system.  I used a radio shack multi-output

lighter plug the other day with my old MP3 player and got

a nasty ground loop whine when I had the thing plugged in.

On batteries it was great.   My concern is that perhaps with

an inverter or with a prebuilt converter that I won't have

a common ground potential.



Thanks for the tips thus far.



Tim Olson - RV-10 N104CD - Flying

do not archive

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Fri Mar 17, 2006 7:12 am Post subject: 5V regulated supply

 	  Quote: 	
		   

 

...

 One of the players had an AC supply that says 5V(at)1A, and the

 other says 5V(at)2A, so I would have thought the 7805 had a

 fighting chance, but I guess that's with a heatsink or something.


	


Just for grins I did a search on Google. Seems that Mouser has several 

that might work for you. Mouser is having a blow-out on discontinued C&D 

switching DC-DC converters. Prices for a complete power supply capable 

of delivering 25A at 5V are in the $10 range. There are also other 

manufacturers.



Give the time and effort needed to build something vs. just buy a 

high-quality DC-DC converter, I think the answer is pretty clearly "buy".



Give Mouser a call and tell them you need a 12V-in 5V-out supply that 

can be isolated or non-isolated. You should be able to find something at 

under $30.



-- 

Brian Lloyd                         361 Catterline Way

brian-yak at lloyd dot com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

- Antoine de Saint-Exupery

Tim(at)MyRV10.com
Guest

Posted: Fri Mar 17, 2006 10:46 am Post subject: 5V regulated supply

Well, the ground loop in my case, I think it more like this:

(I called PS Engineering to verify)

The power is at airframe ground potential.  The Audio panel also

grounds the barrels and shields to the same potential.  But now,

if you use a DC-DC converter that's isolated, sure it puts out

5V between the 2 wires, but that voltage can often be many volts

above source input from a ground potential viewpoint.  So

You might have ground = +8V and Power = +13V.   Yes, it's 5V, but

the grounds are not equal.  So then there's the potential

difference between the shield or barrel on the output wire

of the audio jack on the MP3 player, to the potential of the

barrel or shield on the audio panel when you plug them together,

and THAT's where the problems occur.  It's not so much of

a "ground loop" issue, as it is a ground potential issue.

If you built a simple 3-pin regulator at the same ground potential,

you shouldn't have that problem....or, if you make sure your

DC-DC converter is not isolated from ground on the output it should

work too.  You can buy them various ways.

The noise I had didn't increase with RPM or anything else....it was

more of a gradually increasing screech that got louder and louder

until you couldn't listen to it anymore.

One side note....I have both Bose headsets and other headsets with

ANR upgrade kits in them.  I have ANR power jacks in the plane

that run 9V via a DC-DC converter.  It's an isolated converter.

It works great with those headsets, but Bose internally wires

their grounds a bit different, using the signal ground to carry

the power ground as well.  I originally the power source for

the bose coming off those other isolated ANR jacks, but it didn't

work.  As soon as I moved them to be on the same ground potential

as the rest of the system, and didn't attach to the other isolated

jacks, my headsets worked.  So there is truth to how this

works.  I just don't have a lot of time for shopping.

Thanks Brian though for passing on the mouser info.  I'll try to surf

them up today.  Hopefully I can get this done quick.

Tim

Tim Olson - RV-10 N104CD - Flying

do not archive

Ken wrote:

 	  Quote: 	

 Tim

 That intrigues me if you really had a ground loop whine with the device 

 grounded to the cig lighter plug. Was it in sync with the strobes or 

 transponder? My metal cig lighter outlets are mounted on a metal 

 instrument panel and I wondered if I might have to in the future 

 insulate them for some devices. I thought that was unlikely as most 

 everything goes to a common ground point in my machine. If you really 

 have a ground loop issue then I would expect it to still be there with 

 an inverter plugged into the same place although I guess extra 

 components in the inverter etc. might filter the noise out.

 I would not expect a problem if the entertainment devices are insulated 

 from the airframe with no local grounds. ie insulate the device and run 

 both power and ground wires back to the cig lighter plug. My next step 

 would be to insulate the cig lighter outlet ground from the airframe if 

 you think the noise is being picked up in the ground between the outlet 

 and the common airframe grounding point/battery/alternator. You can get 

 plastic outlets from marinas but they don't seem to retain the plug very 

 well. Might be easier to filter the power I suppose.

 Ken

 Tim Olson wrote:

> 

>

> Thanks for the suggestions, guys.   Time is a factor too as I'm

> hoping to use this all on the way to Sun-N-Fun.

> So far I see these as options:

> http://www.powerstream.com/dda.htm

> http://www.powerstream.com/mini-itx.htm

> The national semiconductor kit is appealing too, although once you

> get to $30 it starts to make sense to buy a completed unit if

> possible

>

> I'm starting to lean back towards just buying another inverter

> to dedicate to the plane, since it would be pretty flexible

> for many uses, and is something I can just grab locally.

>

> The largest concern with this whole project, and the reason

> I wanted to build it, is that I want to ensure that the power

> to the video/audio box is at the same ground potential

> as the plane's system.  I used a radio shack multi-output

> lighter plug the other day with my old MP3 player and got

> a nasty ground loop whine when I had the thing plugged in.

> On batteries it was great.   My concern is that perhaps with

> an inverter or with a prebuilt converter that I won't have

> a common ground potential.

>

> Thanks for the tips thus far.

>

> Tim Olson - RV-10 N104CD - Flying

> do not archive

>  

>

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Fri Mar 17, 2006 11:40 am Post subject: 5V regulated supply

Tim Olson wrote:

 	  Quote: 	
		   

 

 Well, the ground loop in my case, I think it more like this:

 

 (I called PS Engineering to verify)

 The power is at airframe ground potential.  The Audio panel also

 grounds the barrels and shields to the same potential.  But now,

 if you use a DC-DC converter that's isolated, sure it puts out

 5V between the 2 wires, but that voltage can often be many volts

 above source input from a ground potential viewpoint.  So

 You might have ground = +8V and Power = +13V.   Yes, it's 5V, but

 the grounds are not equal.  


	


If the power supply is isolated then that means that neither output wire 

is referenced to the input ground. In fact, there is no DC electrical 

path from input to output at all. In that case it is completely safe to 

tie the -5V lead to ground giving you ground an +5V relative to ground. 

That will work just fine.



I have experienced audio problems with portable audio devices plugged 

into audio panels when powered by the aircraft's electrical system and 

power input was NOT isolated. Problems went away when the device was 

operated off its own battery.



Brian Lloyd

brian-yak(at)lloyd.com

Tim(at)MyRV10.com
Guest

Posted: Fri Mar 17, 2006 11:41 am Post subject: 5V regulated supply

Great tip Brian,  I found them on Mouser, found a 10A version

that will do what I need, for only $8.50.   Bought

2 just because they were cheap.  Should easily be able to

do the job.  I'll post back if it doesn't work.  I bought

the NEF0100500S0.

Tim Olson - RV-10 N104CD - Flying

do not archive

Brian Lloyd wrote:

 	  Quote: 	

> 

>

> ...

> One of the players had an AC supply that says 5V(at)1A, and the

> other says 5V(at)2A, so I would have thought the 7805 had a

> fighting chance, but I guess that's with a heatsink or something.

 Just for grins I did a search on Google. Seems that Mouser has several 

 that might work for you. Mouser is having a blow-out on discontinued C&D 

 switching DC-DC converters. Prices for a complete power supply capable 

 of delivering 25A at 5V are in the $10 range. There are also other 

 manufacturers.

 Give the time and effort needed to build something vs. just buy a 

 high-quality DC-DC converter, I think the answer is pretty clearly "buy".

 Give Mouser a call and tell them you need a 12V-in 5V-out supply that 

 can be isolated or non-isolated. You should be able to find something at 

 under $30.

Tim(at)MyRV10.com
Guest

Posted: Sun Mar 26, 2006 4:52 pm Post subject: 5V regulated supply

I wanted to post back to the list that I did get these parts

and have them working.  I actually had to re-order as I accidently

ordered the ones listed below, and I needed NEF0100500B0.  The other

ones were surface mount...didn't catch that quick enough.

The 5V DC-DC converters hold a solid 5V real well, it's a 10A unit,

and has multiple outputs.  I have now flown and used it and it works

very good.  I don't get the huge screeching nose I used to.  I

do still get a slight alternator whine, so I'd be curious as to how

an isolated converter would be in comparison....I may order one

just to try it out.  They were only $8.50, so it's a great deal

on a nice converter.

Tim

Tim Olson - RV-10 N104CD - Flying

Tim Olson wrote:

 	  Quote: 	

 Great tip Brian,  I found them on Mouser, found a 10A version

 that will do what I need, for only $8.50.   Bought

 2 just because they were cheap.  Should easily be able to

 do the job.  I'll post back if it doesn't work.  I bought

 the NEF0100500S0.

 Tim Olson - RV-10 N104CD - Flying

 Brian Lloyd wrote:

> 

>

>> 

>>

>> ...

>> One of the players had an AC supply that says 5V(at)1A, and the

>> other says 5V(at)2A, so I would have thought the 7805 had a

>> fighting chance, but I guess that's with a heatsink or something.

> Just for grins I did a search on Google. Seems that Mouser has several 

> that might work for you. Mouser is having a blow-out on discontinued C&D 

> switching DC-DC converters. Prices for a complete power supply capable 

> of delivering 25A at 5V are in the $10 range. There are also other 

> manufacturers.

>

> Give the time and effort needed to build something vs. just buy a 

> high-quality DC-DC converter, I think the answer is pretty clearly "buy".

>

> Give Mouser a call and tell them you need a 12V-in 5V-out supply that 

> can be isolated or non-isolated. You should be able to find something at 

> under $30.

>

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