Mimic panel circuit

[aitchem]

Hi,
I am making a mimic/switch panel for my wee boat.
I haven't been able to find a definitive way of wiring the LED's.
What I want is, for the LED to go out should the bulb blow.

I thought it was a simple matter of putting the LED in the feed line to the nav bulb, but, it seems to be I have to make it in a parallel circuit with some resistor connected.
Would this go out when the nav bulb blows or a break in the wiring occurr.?

thx
Howard

 

[alahol2]

I investigated doing this years ago. It's apparently not easy. I was given the following suggestion, which seemed the easiest, but I never tried it...

 

[rogerthebodger]

get some reed relays and coil the wire to the nav lights around the reed relay.

You will need to use trial and error to determine the number of coils needed to cause the reed to close. The led and dropper resistor can then be driven by the reed switch so that if no current flows to the nav bulb either by the bulb blowing of a break in the wire to the nav light the led will no light up.

 

[elton]

No need to get clever with relays or transistors.

If you wire an LED (with appropriate series resistor) in parallel with a 12 bulb, the LED will illuminate if the bulb blows. The bulb has a much lower resistance than the LED/resistor combination so will effectively short circuit it - until the bulb blows.

 

[aitchem]

No need to get clever with relays or transistors.

If you wire an LED (with appropriate series resistor) in parallel with a 12 bulb, the LED will illuminate if the bulb blows. The bulb has a much lower resistance than the LED/resistor combination so will effectively short circuit it - until the bulb blows.

Thanks, but, that's the opposite effect to what I want.
I want the mimic panel to "mimic" what the navigation lights are doing

 

[claudio]

No need to get clever with relays or transistors.

If you wire an LED (with appropriate series resistor) in parallel with a 12 bulb, the LED will illuminate if the bulb blows. The bulb has a much lower resistance than the LED/resistor combination so will effectively short circuit it - until the bulb blows.

I don't think that will work.
You should still have 12V on the end of the wire if the bulb blows or not.

 

[ProDave]

You must come from a control systems engineer, or plant maintenance background to want that sort of panel on a boat

The only way is a reed relay or transistor as already described.

 

[elton]

Thanks, but, that's the opposite effect to what I want.
I want the mimic panel to "mimic" what the navigation lights are doing

Double-pole-single-throw switch needed. Wire the bulb through one pole, and the led through the other. But it won't go out if the bulb blows.

 

[aitchem]

You must come from a control systems engineer, or plant maintenance background to want that sort of panel on a boat

............or a CONTROL Freak.
No, it's what I saw on a Swan, so I can pretend I have a S&S Swan when I'm flicking my switches. Anyway it cost 50 squid to water jet the aluminium.
I need to get my money's worth.

 

[prv]

I invested a lot of time and effort in making a nice panel for Kindred Spirit, with clever touches like the instrument and compass lights coming on with the nav lights, and the steaming light coming on when the engine is running. But I didn't feel any need for indicators to show whether the lights are lit or not - a glance up the masts when I turn them on is not exactly a chore.

Pete

 

[alahol2]

It was many years ago that I first investigated this. At the time I was sailing a catamaran with a large masthead float and it was impossible to tell if the masthead light was on or not. It seems such an obvious function that a telltale light should prove that current is flowing into the equipment rather than just the switch being on. You would have thought someone (manufacturer) would have come up with an inline 'module' that does just that.

 

[theoldsalt]

Aitchem,

I think this panel does what you want.

http://www.svb24.com/index.php?sid=1fbef854691985a4c0d3635ffaae7699&cl=details&cnid=13053&anid=306

You might be able to find the circuit diagram for it somewhere and incorporate the circuits it into your panel.

 

[maxi77]

I looked into this when I was making my light panel. You really need to monitor the current flow, so the options are the turns round the reed switch as mentioned above or the smart chips that some cars have to tell you a light has failed. When I looked they were not easy to find so I gave up.

 

[ghostlymoron]

I have this facility on my Merc and find it useful especially on the brake lights which are difficult to test unless you have very long (and bendy) legs or can park outside a shop window. However, on a boat at night, you should be up on deck anyway and can easily see if your lights are working unless it's a strange kind of boat. I think you are being too complicated.

 

[Tati B]

Somtimes it's nice to check the masthead light is working before you are about to set off on a passage, starting in bright daylight, but going overnight. Can't see the light in the daylight, haven't used it for a while. Do you, climb the mast to see, take the chance, or have a nice shiny instrument light letting you know it's working. It is over the top, up it is useful.

 

[prv]

For what it's worth, I can see my masthead light in daylight (nice bright Bebi LEDs), but I appreciate that's not true for everybody.

Pete

 

[aitchem]

I thought this would be an easy part of the project.
I understand the reed switch idea, and will investigate.