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posted to rec.boats.electronics
jon doe
 
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Default Load In Use Indicator Circuit Needed

Hi:
Looking for a simple circuit idea that will tell us when a 12V DC load is
activated. This is a critical load so we don't want to do anything that will
make it unreliable. The circuit just has to activate a tiny relay when the
load is going. Any ideas?
Thanks


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nimbusgb
 
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Default Load In Use Indicator Circuit Needed

What kind of load? How is it activated?

Simply, an opamp connected across a current sensing shunt in a voltage
comparator configuration will work.

Putting the relay coil in line with the sensed loads feed 'might' also
work, depends on the loads etc.

Ian

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Electricky Dicky
 
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Default Load In Use Indicator Circuit Needed

On Sat, 4 Mar 2006 23:35:48 -0500, "jon doe" wrote:

Hi:
Looking for a simple circuit idea that will tell us when a 12V DC load is
activated. This is a critical load so we don't want to do anything that will
make it unreliable. The circuit just has to activate a tiny relay when the
load is going. Any ideas?
Thanks

Take a reed relay element and take a number of turns of your load wire
around it! If the required switched load is too great for the reed
then slave it through a larger relay!
Cannot get much simpler than that!

Richard

Nb "Pound Eater" Parkend G+S
Please remove your hat when replying
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chuck
 
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Default Load In Use Indicator Circuit Needed

What are you willing to define as "evidence" that the load is activited?
A specific level of current drawn by the load? Presence of 12 VDC at the
load? Switch to the load in the "on" position? Presence of the load's
output (e.g., sound, heat, light, motion, water flow, etc.)? The load's
output is usually, but not always, present when the load is drawing
current of course. An electronic navigation device could draw current
forever and yet not work at all.

The most obvious solution (power the relay with the same switch you use
for the load) is probably the most reliable method if all you want to do
is verify that power to the load is switched on.

Other seem to have figured out what you are seeking from your post, but
I can't see the info there.

Chuck





Electricky Dicky wrote:
On Sat, 4 Mar 2006 23:35:48 -0500, "jon doe" wrote:


Hi:
Looking for a simple circuit idea that will tell us when a 12V DC load is
activated. This is a critical load so we don't want to do anything that will
make it unreliable. The circuit just has to activate a tiny relay when the
load is going. Any ideas?
Thanks


Take a reed relay element and take a number of turns of your load wire
around it! If the required switched load is too great for the reed
then slave it through a larger relay!
Cannot get much simpler than that!

Richard

Nb "Pound Eater" Parkend G+S
Please remove your hat when replying

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posted to rec.boats.electronics
jon doe
 
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Default Load In Use Indicator Circuit Needed

Hi:

Thanks for the responses. The load is a very quiet water pump. It draws
between 5 and 40 amps depending on water load. We need to know not just when
the on/off breaker is activated, but when the pump is actually on and
drawing battery load. The circuit will drive an indicator lamp via a relay.

I have some small reed relays, do you think a coil of the pump's feed wire
will trip it to make contact? That would be easy.

Thanks


"jon doe" wrote in message
...
Hi:
Looking for a simple circuit idea that will tell us when a 12V DC load is
activated. This is a critical load so we don't want to do anything that

will
make it unreliable. The circuit just has to activate a tiny relay when the
load is going. Any ideas?
Thanks






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posted to rec.boats.electronics
Electricky Dicky
 
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Default Load In Use Indicator Circuit Needed

On Sun, 5 Mar 2006 14:07:57 -0500, "jon doe" wrote:

Hi:

Thanks for the responses. The load is a very quiet water pump. It draws
between 5 and 40 amps depending on water load. We need to know not just when
the on/off breaker is activated, but when the pump is actually on and
drawing battery load. The circuit will drive an indicator lamp via a relay.

I have some small reed relays, do you think a coil of the pump's feed wire
will trip it to make contact? That would be easy.

Thanks


"jon doe" wrote in message

Just look at the specs on reed relay elements. if trigger level is 100
Ampere turns then 20 turns around element will give you what you want.
Simple option for encapsulated relays is to break open case and cut
off existing fine wire coil. You now have a former to wind your heavy
gauge wire.. Otherwise wind your wire around a screwdriver of similar
diameter to the element then slide element in. I suggest that you do
not wind directly on element - they are fragile!
I have done just what you are requiring with a water pump. the reed
switches on a battery clock. Runtime of clock tells me the state of my
water tank. Its a very cheap but working option.

Richard

Nb "Pound Eater" Parkend G+S
Please remove your hat when replying
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posted to rec.boats.electronics
 
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Default Load In Use Indicator Circuit Needed

How about using an AMMETER ?
http://en.wikipedia.org/wiki/Ammeter

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posted to rec.boats.electronics
 
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Default Load In Use Indicator Circuit Needed

Yes, I know the other suggestions above are actually home-made
ammeters. Don't blast me.

I know there are small aircraft ammeters with built in alarms, which
you
might find beneficial... not sure what marine offering exist.

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posted to rec.boats.electronics
Wayne.B
 
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Default Load In Use Indicator Circuit Needed

On 6 Mar 2006 07:22:48 -0800, "
wrote:

How about using an AMMETER ?
http://en.wikipedia.org/wiki/Ammeter


For a simple indicator, they take up too much panel space.

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posted to rec.boats.electronics
Del Cecchi
 
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Default Load In Use Indicator Circuit Needed


"Wayne.B" wrote in message
...
On 6 Mar 2006 07:22:48 -0800, "
wrote:

How about using an AMMETER ?
http://en.wikipedia.org/wiki/Ammeter


For a simple indicator, they take up too much panel space.

put a light bulb, of low wattage and appropriate voltage across the
contacts. Bulb lights when pump is off. Or put a relay coil (NC) in
place of the bulb and use to light bulb when contacts close. A small
current would flow through the pump all the time but it shouldn't do
anything.


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