Robert M

Robert M

Well Known Member
DISCLAIMER: I know very little about how electricity works.

I was wanting to put an indicator light in the circuit for my fuel pump to indicate operations. I've tried a few things but nothing works. I can get the pump to run but no light or the light comes on and no pump.

Here's a pic of the current wiring...

fuelpumpwiring_zpsebe4a3b2.jpg


I didn't have it in the pic but there is a 5 amp fuse between battery and switch.

Any suggestions as to adding a light to the system?
 
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For what its worth, I installed one. I still forget and leave the darn thing running. I have a blue light. I have had passengers ask "What does that mean?"
 
AltonD said:
For what its worth, I installed one. I still forget and leave the darn thing running. I have a blue light. I have had passengers ask "What does that mean?"
Click to expand...
Aha! You should never use blue. :D The eye is not very sensitive to blue. The luminance value (brightness) comes from about 30% Red, 60% Green, 10% Blue. You should use red or green (or red+green = yellow) and then make it flashing and then put some words on it (legend) like "DANGER".
 
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Dummy light

I rigged up a white indicator light on my panel
For the fuel pump.

Very easy. Just hook it to the panel switch
to the fuel pump. When the pump is powered, the light
Is as well.

Steinair sells very nice little indicator lights.
various colors.
 
GrayHawk said:
Aha! You should never use blue. The eye is not very sensitive to blue. The luminance value (brightness) comes from about 30% Red, 60% Green, 10% Blue. You should use red or green (or red+green = yellow) and then make it flashing and then put some words on it (legend) like "DANGER". :D
Click to expand...

In the airline world, a blue light is used to show "a temporary system in normal operation".

It's my opinion that different color lights are a good idea to allow the pilot to react to a situation based on color. If all warning lights are red then we learn to ignore a light because we expect to see a red light when the fuel pump is on. If the red light happens to be "low oil pressure" we might not notice until something bad happens.

I would keep the number of lights to a minimum. Use green or blue for things like fuel pumps, flaps. I would save red and yellow for things that are bad and will be bad soon items.

David
 
IMHO, placement of annunciator lights is important too. When I purchased my plane, the buddy that sold it to me and checked me out in it, would ask me "what the heck is that boost pump light still doing on". It was a little green LED placed way down in the lower right corner of the panel (RV-6), just above the air vent...almost worthless there!

When I did a panel upgrade, annunciator placement was an important element to me. I went with this:
panel%2520left.jpg


I did use blue, because (as David said) blue in the jet at work means system or valve position or normal operation (including fuel crossfeed and spar valve position). I just used blue to indicate boost pump (it equates to fuel in my brain), and green to indicate landing light (like 3 green, green equates to landing gear or landing light in my pea-brain;)).

FWIW, I set my annunciator system methodology up as cool colored lights (green/blue) OK for TO and LNDG, hot colored lights (yellow/red) not OK for TO and LNDG. I think I heard Paul Dye describe it that way...probably stole it from him!

I don't disagree that blue or green are less attention getting, but also concur with not wanting to desensitize to red or yellow lights. Put them in front of your eyeballs, and all colors should work OK. And if you fly at night, the blue and green being a bit dimmer is not a bad thing during TO and LNDG either.

Sounds like the OP has the light rigged already, so none of this may matter to him, but those contemplating an annunciator panel might take nugget away.

Cheers,
Bob
 
My fuel pump switch lit red, and a amber light was included with the annunciator lights. I had a problem forgetting the fuel pump with Piper products.
 
I have...

... done the same thing: wired a light so it comes on when the fuel boost pump is on.
I have installed an EXP-2 switch panel, so wiring the light was pretty easy.

I have also installed three more warning lights:
(right seat is pilot seat)




The warning lights are from right to left:
Red: low oil pressure
Amber: alternator offline
Blue: fuel boostpump is on
Green: defroster-fans are on
 
Flap switch wiring with a light

Here is how my flap switch is wired. I don't suppose I can do the same thing with a light for my flap switch, can I - some how? I'm planning to use green lights. For some reason I got it my head that a red light means a bad thing.

flapswitchwiring_zps16346c60.png


I can't take credit for this image, I borrowed it from someone on this forum a long time ago and I can't remember who - sorry.
 
On a slightly different tack. I have installed LEDs across the fusesfor pump etc. Those LEDs don't light up unless the fuse has blown. That will show me if a pump is inoperative even if the switch is on.
 
Robert M said:
Here is how my flap switch is wired. I don't suppose I can do the same thing with a light for my flap switch, can I - some how? I'm planning to use green lights. For some reason I got it my head that a red light means a bad thing.

I can't take credit for this image, I borrowed it from someone on this forum a long time ago and I can't remember who - sorry.
Click to expand...

If you use an incandescent light bulb for your "flaps operating" indicator you can wire it in parallel with the flap motor just like Brantel said above. Don't even need to pay attention to polarity. It will light up any time the motor runs, in either direction. A LED indicator would make things a little more complicated, but using 2 LEDs (one for flaps going up, one for down) would be rather easy - install them both in parallel but reverse the polarity of one LED in relation to the other.

I've never seen a "flaps operating" indicator in a panel though. Can you help me understand what the utility would be?
 
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The circuit that Brantel put up,

2l972wn.jpg


only shows that the power to the pump is on. The pump could be not working, or switched to an empty tank, yet the light would show pump on.

If you are looking to have an indicator that tells when there is aux pump delivering pressure, then you need something quite different.

For normal day to day use, the above should work just fine, but you should be aware of the little gottcha I mentioned.
 
Tell us more...Mike.

Mike,

Your comment above has merit. The real reason we want the light on the pump is to know that it's working, not just receiving current. How would you suggest wiring something up to see that the pump is actually delivering fuel (pressure transducer or something in line?)
 
Well, if you have a fuel pressure gauge, you already have the info available.

If you want a warning light, a simple pressure switch in the fuel line will do it, but then you are inducing another possible leak location. Vans supplied pressure sender manifold can handle this chore.

If you really want to go custom, a DPST pressure switch could easily be rigged to show Green for pump on and pressure present, or Red for pump on no pressure.

My main purpose in the prior post was to alert folks to the fact that an indicator light "ON" doesn't necessarily mean there is pressure.

For what I would use such a light, it would be to remind me to turn off the pump after take off.
 
For what it is worth, most of the fuel pumps in our RV's are "continuous" duty rated. If you don't catch it with your checklist, catch it with your scan. If it runs for a while what's the harm? Maybe Don can chime in on his pumps?
If you do install a light for whatever purpose, have a means to check the light. Also, make sure it dims. One of the factors that led to an accident recently was a display that did not dim during a critical time of the flight
There is no free lunch. Everything added to your system is another point of failure and one more thing to manage.
You can tell I don't have a boost pump light huh?:)
 
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To be really picky about it, the circuit shown only indicates that there is power to the indicator light. The branch of the wire to the pump could have a break in it.
 
You guys do realize we are building RV's here don't you? Not Space Shuttles.....

There are a million failure modes to check for, wires that could get broken, bulbs that can burn out, lights that can be the wrong color or too bright, push to test circuits that must be added, etc. etc. etc. This can snowball totally out of control fast!

The original poster is way behind the power curve on all of that...He needed a simple circuit to get him out of the ditch. That is what I gave him....
 
krw5927 said:
If you use an incandescent light bulb for your "flaps operating" indicator you can wire it in parallel with the flap motor just like Brantel said above. Don't even need to pay attention to polarity. It will light up any time the motor runs, in either direction. A LED indicator would make things a little more complicated, but using 2 LEDs (one for flaps going up, one for down) would be rather easy - install them both in parallel but reverse the polarity of one LED in relation to the other.

I've never seen a "flaps operating" indicator in a panel though. Can you help me understand what the utility would be?
Click to expand...

If you want to use an LED instead of an incandescent lamp for the flap run indicator, you'll need to put the LED and a current limiting resitor (510 ohms or so) in series across the + and - terminals of a bridge rectifier, observing proper polarity. The two ~ terminals on the rectifier go to the flap motor poles, which are not polarity sensitive.

Flap run indicators are used because Van's flap motors do not have limit switches and will continue to run even when at their end limits. Many people use an (ON)-OFF-ON DPDT switch instead of the standard Van's switch, which will not automatically shut off when released.

Finally, all of this simple lamp stuff works fine for Day VFR. For night VFR, things get tricky because you'll want to dim the lamps to avoid being dazzled. An annunciator controller makes this easy. See http://store.makerplane.org/annunciator-controllers-il-12a/ for a typical circuit. This is an open-source design.
 
Robert, give me a call.

You may not remember but I had a light wired to my pump in my first panel.
 
Works for me

Here is my pump light wired as per Brantel's schematic.
Your fuel pressure gauge will tell you if it's actually pumping.
Notice it's green, green means good. If you forget to turn it off, no harm done.

IMG_2568.JPG


You really don't need a flap light just look out the window and get a visual on the flaps.
If you want to get fancy on the flaps get one of these
http://www.tcwtech.com/IFC-1-page.htm
 
vlittle said:
If you want to use an LED instead of an incandescent lamp for the flap run indicator, you'll need to put the LED and a current limiting resitor (510 ohms or so) in series across the + and - terminals of a bridge rectifier, observing proper polarity. The two ~ terminals on the rectifier go to the flap motor poles, which are not polarity sensitive.

Flap run indicators are used because Van's flap motors do not have limit switches and will continue to run even when at their end limits. Many people use an (ON)-OFF-ON DPDT switch instead of the standard Van's switch, which will not automatically shut off when released.

Finally, all of this simple lamp stuff works fine for Day VFR. For night VFR, things get tricky because you'll want to dim the lamps to avoid being dazzled. An annunciator controller makes this easy. See http://store.makerplane.org/annunciator-controllers-il-12a/ for a typical circuit. This is an open-source design.
Click to expand...

Thanks, Vern, that makes sense. I guess I hadn't thought of folks using a switch that latched in the "flaps up" direction.

BTW I built a couple of your annunciator controllers and love them! Thank you for sharing the design. The dimming option and "push to test" feature are fantastic!
 
vlittle said:
Flap run indicators are used because Van's flap motors do not have limit switches and will continue to run even when at their end limits. Many people use an (ON)-OFF-ON DPDT switch instead of the standard Van's switch, which will not automatically shut off when released.QUOTE]

I think the best thing to do will be to go without the flap run indicator. My switch is an (ON)-OFF-(ON) so there's realy no way it will stay on. My concern was more about the flap motor becoming a runaway if a "weird" short was to cause it to take off without input from me.

The fuel pump light works great by running in parallel as suggested by MikeS. The flap motor run indicator is a bit trickier because of the nature of the wiring. I tried to wire the flap run light as krw5927 and the result was tat the light lit in only one flap operating direction. This is with an incandecent light from AS.

Yes, N941WR, I remember our conversation (LOL) and I am using a green light. Thanks for that insight.
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Bill_H said:
To be really picky about it, the circuit shown only indicates that there is power to the indicator light. The branch of the wire to the pump could have a break in it.
Click to expand...

I think the original intent here is as a reminder that the switch is on. Simpler the better.
 
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