In article ,
Michael A. Terrell wrote:
If your battery develops an open cell, or the cable falls off you'll
lose lots of electronics.

You might well. Which is nothing to do with load dump. You'd probably
loose electrics in a fire too.

Go to news:sci.electronics.design and tell them that "Load Dump" in
automotive electrical systems is a myth. They will tell you just how
wrong you are.

Strange it's never been a problem in practice in all the years I've been
playing around with cars.

--
*Drugs may lead to nowhere, but at least it's the scenic route *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
Michael A. Terrell wrote:

If your battery develops an open cell, or the cable falls off you'll
lose lots of electronics.

You might well. Which is nothing to do with load dump. You'd probably
loose electrics in a fire too.

its precisely load dump. You've got an inductive alternator feeding a
battery, the battery disconnects... the result is predictable enough.


Go to news:sci.electronics.design and tell them that "Load Dump" in
automotive electrical systems is a myth. They will tell you just how
wrong you are.

Strange it's never been a problem in practice in all the years I've been
playing around with cars.

electrocution has probably never been a problem for you either, but its
real nonetheless.


NT

wrote in message
ups.com...
Dave Plowman (News) wrote:
In article ,

BTW, the first transistor car radio I had was a hybrid kit where only
the
AF was handled by transistors. Early '60s. No sign of anything like that
on it. Perhaps Lucas electrics couldn't produce much over 14 volts. ;-)

I presume it had an LC power filter.

Last time I had Lucas electrics it boiled the battery.

I've never had anything from Lucas but I've noticed in the motorcycle
community whenever you see the word Lucas it's followed by the phrase
"prince of darkness".

In article om,
wrote:
If your battery develops an open cell, or the cable falls off you'll
lose lots of electronics.

You might well. Which is nothing to do with load dump. You'd probably
loose electrics in a fire too.

its precisely load dump. You've got an inductive alternator feeding a
battery, the battery disconnects... the result is predictable enough.

You ever measured the voltage available from an open circuit alternator?

Go to news:sci.electronics.design and tell them that "Load Dump" in
automotive electrical systems is a myth. They will tell you just how
wrong you are.

Strange it's never been a problem in practice in all the years I've
been playing around with cars.

electrocution has probably never been a problem for you either, but its
real nonetheless.

Another red herring.

--
*If you try to fail and succeed, which have you done? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
T Shadow wrote:
I've never had anything from Lucas but I've noticed in the motorcycle
community whenever you see the word Lucas it's followed by the phrase
"prince of darkness".

Not defending Lucas, but the very worst designed and constructed
distributor I ever saw was a Delco on a Vauxhall. Don't have any love for
Delco batteries, either.

--
*I wished the buck stopped here, as I could use a few*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article om,
wrote:

If your battery develops an open cell, or the cable falls off you'll
lose lots of electronics.

You might well. Which is nothing to do with load dump. You'd probably
loose electrics in a fire too.

its precisely load dump. You've got an inductive alternator feeding a
battery, the battery disconnects... the result is predictable enough.

You ever measured the voltage available from an open circuit alternator?

Go ask sci.tron.des if you want to know


NT

"Dave Plowman (News)" wrote in message
...
In article ,
T Shadow wrote:
I've never had anything from Lucas but I've noticed in the motorcycle
community whenever you see the word Lucas it's followed by the phrase
"prince of darkness".

Not defending Lucas, but the very worst designed and constructed
distributor I ever saw was a Delco on a Vauxhall. Don't have any love for
Delco batteries, either.

I've had 2 Delco batteries last 8 years. Went out of my way and paid a
little extra to replace the last one with another Delco. Probably should
have made sure who's making them now and where but the battery was do-a-do
so couldn't wait.

I've seen the "prince of darkness" quote a lot of times. No one ever
disagreed. Probably referring to 20+ year old equipment though.

"w_tom" wrote in message
ups.com...
As I said how did a crude early germanium transistor radio survive, then?
They often did not which is why load dump was discovered. Same failure
also occurred to alternators with failed germanium diodes. The Detroit
manufacturer even overnight delivered those replacement alternators.
Load dump created by a manufacturing design defect created germium
semiconductor failure.


One point no-one has mentioned yet- cars fitted with germanium based radios
would *generally* predate the widespread adoption of alternators and would
have been fitted with generators/dynamos and voltage/current regulator
boxes.

Morse

On Sat, 16 Dec 2006 11:17:39 -0700, Bill Jeffrey
wrote:

lsmartino wrote:

You want to find a charger who outputs nothing more than 6V, and 300 mA
or more. The TV will take the amount of power (consumption in mA) it
needs, meaning that a 500 mA power source will not damage it, because
the TV will only draw 267 mA from the 500 mA power source. Just be
careful of the voltage produced by the charger, because that´s a
critical paramater and it shouldn´t be higher than 6.6V or lower than
5.4V under any circumstances.

To close, the idea of the dropping resistor is an awful one.
Don´t risk frying your TV. It´s more worth having it fuly operational
than the cost of a proper DC regulated power supply.

A voltage regulator IC, or a modified REGULATED charger (modifying it
might be more of a hassle than it first appears) should do fine. If it
were me, I would simply use a series dropping resistor followed by a
shunt filter cap and a shunt 6.3 volt zener. The zener will probably
have to be mounted on a small heat sink - but so would a voltage
regulator IC. Pretty simple.

I may do this. It's the voltage regulator or this. I waited to
reply thinking I'd have more followup to report, but I dont.

Thanks to all.

Bill


If you are inclined to email me
for some reason, remove NOPSAM :-)

On 16 Dec 2006 09:17:51 -0800, "lsmartino"
wrote:


mm ha escrito:

On Sat, 16 Dec 2006 08:48:44 +1100, Franc Zabkar
wrote:

On Thu, 14 Dec 2006 23:05:16 -0500, mm put
finger to keyboard and composed:
My experience is that fully charged AA batteries are usually 1.56
volts x 4 = 6.3 volts, which is exactly half of the resting voltage of
fully charged car batteries, 12.6 volts. I won't be watching tv when
the car is running, but maybe I would sometimes run the car to charge
the car battery, or even to warm the car** Then, iirc and I can
measure it to be sure, the voltage goes up as high as 13.2, half of
which is 6.6. Also, the label on the back of the tv says that it
uses, on average, 1.6 watts, but I will measure its current current
use and not rely on that.

If you are looking to do this on the cheap, then I'd modify a mobile
phone car adapter/charger. But then I have dozens of them.

Do the new ones put out 1.6 watts, which is what the back of the tv
says it uses on average? I have a spare new one.

Do even the old ones put out 1.6 watts?

- Franc Zabkar


If you are inclined to email me
for some reason, remove NOPSAM :-)


Well, 1.6 Watts at 6V is nothing more than 267 mA. (1.6V / 6V = 0.267
A) I would be greatly surprised to find a cellphone charger not able
to produce that amount of current. Check the mA rating of the DC
charger you want to modify, if it provides a *regulated* output of 6V
at 300 mA or more, you will be fine.

That would be darn easy to do. Even though I almost never use a cell
phone, somehow I already have a bunch of car chargers.

I could have tested them all by now, but I got distracted. I did makr
the voltage each puts out, so that will speed things up.

You want to find a charger who outputs nothing more than 6V, and 300 mA
or more. The TV will take the amount of power (consumption in mA) it
needs, meaning that a 500 mA power source will not damage it, because

That I understand.

the TV will only draw 267 mA from the 500 mA power source. Just be
careful of the voltage produced by the charger, because that´s a
critical paramater and it shouldn´t be higher than 6.6V or lower than
5.4V under any circumstances.

OK. Too low is bad?

To close, the idea of the dropping resistor is an awful one. Why?
Because the 1.6 Watts consumption stated in the back label of the TV
probably is an average value, or a maximum one obtained only under
worst case conditions. The consumption power of a TV, radio, or
amplifier, is really a variable one. It will vary depending on how high
the speaker volume is, and even the screen content. For instance, a
white image will demand more power than a mainly dark one. So you
can´t really obtain a fixed voltage just using a fixed dropping
resistor if your load is a variable one. Even worse, as other posters
had previously stated, the DC voltage inside a car can go anywere from
12V to 14V or more.

Yes, you're right about that. I have tried to figure out why it is
high sometimes and low other times, and never been able to correlate
it with anything.

Thanks.

And thanks to all.

So now you have two uncontrolable variable
parameters: a) The voltage source, and b) The power consumption of the
TV.

Don´t risk frying your TV. It´s more worth having it fuly operational
than the cost of a proper DC regulated power supply.


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for some reason, remove NOPSAM :-)

On Sun, 17 Dec 2006 16:38:13 -0500, David Naylor
wrote:

Or probably more likely, in a tent in
a state park, in late winter or early spring, in the South, where I
guess it will be warm enough. If I stay in a tent, I'll make a longer
wire.

Radio Shack has a cig adaptor that is voltage selectable and has many
pugable jacks that fit most everything for around 20 bucks

Wow. I"ll check on that too.

Thanks.

If you are inclined to email me
for some reason, remove NOPSAM :-)

mm ha escrito:

On Sun, 17 Dec 2006 16:38:13 -0500, David Naylor
wrote:

Or probably more likely, in a tent in
a state park, in late winter or early spring, in the South, where I
guess it will be warm enough. If I stay in a tent, I'll make a longer
wire.

Radio Shack has a cig adaptor that is voltage selectable and has many
pugable jacks that fit most everything for around 20 bucks

Wow. I"ll check on that too.

I'd say DON'T- those things are usually crap chinese made unregulated
supplies, the ones i have used have had a sloppy fit in the car jack
too.

b wrote:
mm ha escrito:


On Sun, 17 Dec 2006 16:38:13 -0500, David Naylor
wrote:


Or probably more likely, in a tent in

a state park, in late winter or early spring, in the South, where I
guess it will be warm enough. If I stay in a tent, I'll make a longer
wire.


Radio Shack has a cig adaptor that is voltage selectable and has many
pugable jacks that fit most everything for around 20 bucks

Wow. I"ll check on that too.


I'd say DON'T- those things are usually crap chinese made unregulated
supplies, the ones i have used have had a sloppy fit in the car jack
too.



The one I had was regulated, it contained an LM317.

James Sweet wrote in news:EGdrh.14380$Ch1.11938
@trndny04:

b wrote:
mm ha escrito:


On Sun, 17 Dec 2006 16:38:13 -0500, David Naylor
wrote:


Or probably more likely, in a tent in

a state park, in late winter or early spring, in the South, where I
guess it will be warm enough. If I stay in a tent, I'll make a
longer
wire.


Radio Shack has a cig adaptor that is voltage selectable and has many
pugable jacks that fit most everything for around 20 bucks

Wow. I"ll check on that too.


I'd say DON'T- those things are usually crap chinese made unregulated
supplies, the ones i have used have had a sloppy fit in the car jack
too.



The one I had was regulated, it contained an LM317.


ditto.

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On Tue, 16 Jan 2007 19:28:47 -0600, me wrote:

James Sweet wrote in news:EGdrh.14380$Ch1.11938
@trndny04:

b wrote:
mm ha escrito:


On Sun, 17 Dec 2006 16:38:13 -0500, David Naylor
wrote:
.....
Radio Shack has a cig adaptor that is voltage selectable and has many
pugable jacks that fit most everything for around 20 bucks

Wow. I"ll check on that too.

I'd say DON'T- those things are usually crap chinese made unregulated
supplies, the ones i have used have had a sloppy fit in the car jack
too.

The one I had was regulated, it contained an LM317.

ditto.

I'm not try to answer the question of whether RS sells 2 or 3
different models of this, one without and one or two with.

Over the past few days I put the jack on the tv, the Sony Watchman.

And I checked the voltage on all my cell phone car chargers. I have a
few extra because I bought some at hamfests for a friend, and the
first two didn't fit (a dollar apiece.) None have the voltage or
current capability marked, but the voltages we

5.47, 6.06**, 7.05, 7.67, 8.98, 9.63
I didn't think there would be this much differnce, since I thought all
cell phones used similar 3 cell batteries.

**This one I keep in my car for my own cellphone
(that I never use 8-) ).

I only tested the two with the lowest voltage:

Setting 1 Setting 2
No load Sound Only Sound and Picture

5.48 5.43 2.50
sound quivers no sound or picture

6.06 6.03 2.52
sound is fine no sound or picture

I'm afraid to try any of the chargers with higher voltage, especially
since the voltage barely drops when used for sound only, and since I
don't think the current capacity will be any higher, so it won't be
enough for picture anyhow.


If you are inclined to email me
for some reason, remove NOPSAM :-)