13 VDC switch

What do you want the cutoff voltage to be? Personally, I'd pick 13.0 volts,
but it is child's play to do any voltage you want.

There will be about a milliampere of quiescent current for the sensor that
will still be on-line when the output shuts off.

Jim



"abripl" wrote in message
ups.com...
You mean I started a new idea? It sure would be handy to plug in
portable devices into the cigarette lighter socket source and not drain
the battery with engine off. OR in case of charging system failure
some non-crucial devices could be turned off automatically. We need
this before November.

RST Engineering wrote:
This is starting to smell very much like the upcoming November Kitplanes
column.

Jim

"RST Engineering" wrote in message
...
What do you want the cutoff voltage to be? Personally, I'd pick 13.0
volts, but it is child's play to do any voltage you want.

There will be about a milliampere of quiescent current for the sensor that
will still be on-line when the output shuts off.

Jim


One-chip solutions designed for this purpose that can detect both
undervoltage and overvoltage are available from several vendors, such as
Maxim.
Example: http://pdfserv.maxim-ic.com/en/ds/MAX6457-MAX6460.pdf

These offer very low quiescent current when off (couple of uA). The output
can be used to activate a relay (maybe needs an extra transistor). I think
you can request free samples.

Rob

A. Maxim is very poor on production delivery.

B. Joe Sixpack in East Undershirt Ohio can't go down to the corner Maxim
store and buy onesie-twosies on Sunday afternoon.

C. One milliampere out of a 25 amp-hour battery will run the battery down
in 25,000 hours (1040 days, or a little less than 3 years). If you don't
fly your airplane but once in 3 years, that's not my problem.

D. Why would you use an unreliable electromechanical device like a relay
when a FET is half the price and a thousand times more reliable?

Jim




"Rob Turk" wrote in message
news:Y7_gg.1536$YI3.268@amstwist00...
"RST Engineering" wrote in message
...
What do you want the cutoff voltage to be? Personally, I'd pick 13.0
volts, but it is child's play to do any voltage you want.

There will be about a milliampere of quiescent current for the sensor
that will still be on-line when the output shuts off.

Jim


One-chip solutions designed for this purpose that can detect both
undervoltage and overvoltage are available from several vendors, such as
Maxim.
Example: http://pdfserv.maxim-ic.com/en/ds/MAX6457-MAX6460.pdf

These offer very low quiescent current when off (couple of uA). The output
can be used to activate a relay (maybe needs an extra transistor). I think
you can request free samples.

Rob

abripl a écrit :
Looking for a ready made 13VDC electronic switch, that switches a
circuit on when voltage reaches 13+VDC - or a simple circuit. It would
be for optional devices I want to go on when the engine is charging and
off when not charging. Any sources? Not sure what to Google for.
-----------------------------------------------------------------
SQ2000 canard: http://www.abri.com/sq2000


Hi abripl,

You'll find what you're looking for there :

http://www.periheliondesign.com/lvwaabm.htm

Or there

http://www.aeroelectric.com/Catalog/AEC/9005/9005.html

Works great with our airplane.

Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr

Yeah,

13V cuttoff sounds right. Most charging systems go to at least 13.5
volts and batteries seldom settle near 13 when not charging. 1 ma is
fine. FET? is that what it takes? Its gota work for low and high loads
same...

RST Engineering wrote:
What do you want the cutoff voltage to be? Personally, I'd pick 13.0 volts,
but it is child's play to do any voltage you want.

There will be about a milliampere of quiescent current for the sensor that
will still be on-line when the output shuts off.

Jim

wrote:
Steve Foley wrote:

"RST Engineering" wrote...


Trivial to design and build.

Jim

Not for me


----------------------------------------------------------------------------------

Yes, even for you :-)

Although he hasn't stated it very well, the original poster is probably
looking for a voltage comparator.


Unfortunately, the original poster's use of the term 'charging' needs
to be defined in electrical terms, and the chances off finding exactly
what he wants in an off-the-shelf package is probably somewhere between
slim and none. But there are numerous examples of such circuits out
there, assembled as well as kits.

-R.S.Hoover


The voltage comparator is straight forward enough, and you could also
probably modify an existing automtive regulator to get the job done.

If he really needs something more upscale, there are low voltage cutout
circuits available. There are some listed he

http://home.cogeco.ca/~rpaisley4/xLowBattery.html

But these are probably beyond a beginner.

I admit I am operating off of almost no sleep and may be missing
something, but to keep it dead simple, why not just put a large diode
between the alternator charging post and the battery. Wire the
accessories behind the diode directly to the charging post. There would
be some forward loss of probably half a volt, but I can't figure it
would mess with the internal regulator as the voltage/current is already
passing through a full wave rectifier. If you have a three wire
alternator with remote voltage sensing, it wouldn't affect it at all.
For that matter, you can get the thing ready wired by buying a battery
isolator from JC Whitney. No need to worry about voltage levels and
whatnot. If the alternator isn't producing a charge your accessories
aren't getting juice -- pretty simple.

Charles

..
"abripl" wrote in message
ups.com...
You mean I started a new idea? It sure would be handy to plug in
portable devices into the cigarette lighter socket source and not drain
the battery with engine off. OR in case of charging system failure
some non-crucial devices could be turned off automatically. We need
this before November.

Ok, I'm operating from memory, but if the objective is to turn "on" only
when the alternator is active, trigger your switch with the stator output -
should be 0 when the alterntor is inactive, and about 1/2 the output voltage
when the alternator is charging. A 6 volt relay would do the job, eh?

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate

Others can do what they want. Personally I want a finished "plug-in,
easy to use" product and not a lifetime hobby of playing with
alternator circuits, or whatever.

Capt. Geoffrey Thorpe wrote:
.

Ok, I'm operating from memory, but if the objective is to turn "on" only
when the alternator is active, trigger your switch with the stator output -
should be 0 when the alterntor is inactive, and about 1/2 the output voltage
when the alternator is charging. A 6 volt relay would do the job, eh?

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate

"RST Engineering" wrote in message
...
A. Maxim is very poor on production delivery.

That's not been my experience, but maybe I've just been lucky. Also, when
they offer samples then the chips are available at least in sample
quantities. That may not mean much if you want to order 100.000 of them, but
for us one-off builders this is fine.

Besides, Maxim was just one example. Linear Technologies has similar chips
and similar sample programs.


B. Joe Sixpack in East Undershirt Ohio can't go down to the corner Maxim
store and buy onesie-twosies on Sunday afternoon.

The samples ship worldwide. If I can get them easily in Hoevelaken, The
Netherlands, Europe then I'm sure they'll ship to East Undershirt Ohio as
well.


C. One milliampere out of a 25 amp-hour battery will run the battery down
in 25,000 hours (1040 days, or a little less than 3 years). If you don't
fly your airplane but once in 3 years, that's not my problem.

Agree, and if you leave your plane for 3 years without flying I'm sure there
will be other issues to worry about..

D. Why would you use an unreliable electromechanical device like a relay
when a FET is half the price and a thousand times more reliable?

Agree again, it's whatever makes you feel happy. I've had luck with either
device. Automotive relays seem pretty reliable, and so are FET's.


Jim

Rob

"jmk" wrote in message
oups.com...

I believe it was "Interesting proof."

I remember it as being 'trivial'. I have always looked with skepticism on
anything called trivial ever since.

And didn't someone finally work
it back out a couple of years ago?

Probably. I've been away from math class for many years now.