13 VDC switch

[abripl]

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

[RST Engineering]

Trivial to design and build.

Jim





"abripl" > wrote in message
ups.com...
> 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
>

[abripl]

Since its so trivial for you, how about a basic indication of the
components hookup or reference to the circuit elsewhere?

Anybody (else) know of a finished product source of this trivial
product? Kit?

RST Engineering wrote:
> Trivial to design and build.
>
> Jim
>

[cavelamb]

abripl wrote:
> Since its so trivial for you, how about a basic indication of the
> components hookup or reference to the circuit elsewhere?
>
> Anybody (else) know of a finished product source of this trivial
> product? Kit?
>
> RST Engineering wrote:
>
>>Trivial to design and build.
>>
>>Jim
>>
>
>
Nope.

That's mostly a roll yer own.

Sounds like a relay circuit to me.

Off the shelf automotive supplies?
Wally World?

[cavelamb]

abripl wrote:

> 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
>

Gonna need a bit more detail, alphabet...

[jmk]

Steve Foley wrote:
> I remember a loooooong time ago, I was in a math class. We were being told a
> story about some math genius who came up with a better something-or-other.
> In the notes was a formula with the notation "Proof is trivial". In the
> hundreds of years since, nobody has been able to prove that formula. It
> appears to be correct, but it's never been 'proven'.

I believe it was "Interesting proof." And didn't someone finally work
it back out a couple of years ago?

I like the college professor who is lecturing and showing the steps to
solve a problem. Step 1...2...3... then as he writes down step three
he adds "and from there it is obvious that..." and writes down step
four. He backs up a minute, stares at the board, looks puzzled.
Mumbles to himself a bit, and finally wanders out of the classroom.

Students sit there puzzled. Five minutes go by, then ten. Suddenly
the professor reappears, beaming from ear to ear. "I was RIGHT!" he
exclaims. "It *IS* obvious!"

[And we need some more info about your "switch." Above 13 volts, below
13 volts, precisely at 13 volts? How much current?]

jmk

[[email protected]]

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.

Some years ago I kitted and sold a simple on-off 'controller' based on
the LM-339 voltage comparator chip that would probably fill the bill.
Although sold as a solar controller, the circuit also served as a
low-voltage indicator, a means of turning on a motor-generator set and
a number of other functions, depending on what voltage was being sensed
and how you adjusted the set-points.

The circuit itself was little more than the practical application of
one of the several circuits provided by the chip manufacturer
(National, as I recall), making the 'design' a trivial task indeed.
The real value was in the circuit board and the accompanying article,
which appeared in 'CTM' magazine, in that you needed a precisely
adjustable power supply to adjust the set-points (ie, turn-on &
turn-off). In the article I provided a schematic for such a power
supply, cobbled up from a salvaged wall-wart, regulation provided by an
LM-317T.

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

[john smith]

In article . com>,
"abripl" > wrote:

> Since its so trivial for you, how about a basic indication of the
> components hookup or reference to the circuit elsewhere?

Look up zener diode for starters.

[RST Engineering]

This is starting to smell very much like the upcoming November Kitplanes
column.

Jim


"cavelamb" > wrote in message
k.net...
> abripl wrote:
>> Since its so trivial for you, how about a basic indication of the
>> components hookup or reference to the circuit elsewhere?
>>
>> Anybody (else) know of a finished product source of this trivial
>> product? Kit?
>>
>> RST Engineering wrote:
>>
>>>Trivial to design and build.
>>>
>>>Jim
>>>
>>
>>
> Nope.
>
> That's mostly a roll yer own.
>
> Sounds like a relay circuit to me.
>
> Off the shelf automotive supplies?
> Wally World?

[abripl]

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]

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
>>
>

[Rob Turk]

"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

[RST Engineering]

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
>
>

[GTH]

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

[abripl]

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
>

[Charles Vincent]

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 here:

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

[Capt. Geoffrey Thorpe]

..
"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

[abripl]

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

[Rob Turk]

"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

[Steve Foley]

"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.

[Jim Logajan]

"Steve Foley" > wrote:
> "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.

I suspect you are all thinking of Fermat's Last Theorem, which states that:

x^n + y^n = z^n

has no non-zero integer solutions for x, y and z when n > 2. Fermat had
written the rather infamous note on this theorem:

"I have discovered a truly remarkable proof which this margin is too small
to contain."

>> 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.

A proof for the theory is presumably now worked out, thought its length is
so long and complex that most doubt that Fermat had a valid proof.

http://en.wikipedia.org/wiki/Fermat's_last_theorem

[Capt. Geoffrey Thorpe]

"abripl" > wrote in message
oups.com...
> 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.
>

Ok, then it sounds like the best solution is something simple like
connecting the stator output from the alternator (on many brands, that't the
terminal with the "S") to a relay.

--
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.

[Gerry Caron]

"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.
>
That's about right, but here's a couple lessons learned the hard way:

I'd like to see some hysteresis in the switching -- say power on at 13.1V
and off at 12.9V.

It would also be a good idea to have some limitation on inrush current or at
least a delayed response. I've seen too many cases where it goes into
oscillations when a device with a hefty inrush pulls the detector voltage
below the switch point which shuts down the power at which point the voltage
recovers and it turns back on and the cycle starts over.

Gerry

[RST Engineering]

"Gerry Caron" > wrote in message
.. .
>
> "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.
>>
> That's about right, but here's a couple lessons learned the hard way:
>
> I'd like to see some hysteresis in the switching -- say power on at 13.1V
> and off at 12.9V.

I never do a comparator without hysterisis.


>
> It would also be a good idea to have some limitation on inrush current or
> at least a delayed response. I've seen too many cases where it goes into
> oscillations when a device with a hefty inrush pulls the detector voltage
> below the switch point which shuts down the power at which point the
> voltage recovers and it turns back on and the cycle starts over.

I was sort of figuring on about a ten second loop constant.

Thanks. How you been, Gerry? Long time no type. Who you working for now?

Jim


>
> Gerry
>

[Gerry Caron]

"RST Engineering" > wrote in message
...
>
> "Gerry Caron" > wrote in message
> .. .
>>
>> "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.
>>>
>> That's about right, but here's a couple lessons learned the hard way:
>>
>> I'd like to see some hysteresis in the switching -- say power on at 13.1V
>> and off at 12.9V.
>
> I never do a comparator without hysterisis.

I figured you probably would. I raised the issue to enlighten the less
experienced.

>
>>
>> It would also be a good idea to have some limitation on inrush current or
>> at least a delayed response. I've seen too many cases where it goes into
>> oscillations when a device with a hefty inrush pulls the detector voltage
>> below the switch point which shuts down the power at which point the
>> voltage recovers and it turns back on and the cycle starts over.
>
> I was sort of figuring on about a ten second loop constant.
>
> Thanks. How you been, Gerry? Long time no type. Who you working for
> now?
>
> Jim

Been doing pretty well. Have made a few posts, but mainly lurk. Work's
been keeping me real busy. I'm still at Rockwell Collins in Melbourne.
Been working on a new integrated surveillance (transponder, TCAS, WxR, and
TAWS) system for the heavy iron.

Gerry