Need a circuit diagram...

[Simpo Two]

There are some things I just can't do. Languages is one, wiring diagrams is another.

This is the problem; can someone kindly post an idiot-proof answer, preferaby a diagram?

Q1: Captain Simpo has a boat with a heating system that uses a controller and a temperature sensor in the saloon. The two are connected by two-core cable. He wants to fit a second temperature sensor in the engine bay, and be able to select which sensor is operative with a two position switch marked 'Engine Bay/Saloon'. Only one sensor will be used at any time. The switch will need its own cable as it's not possible to wire both sensors directly to it.

He thinks he needs a DPDT switch - but got as far as 8 pencil lines all heading together then got stuck... [50 marks]

[Simpo Two]

Aha, I didn't see the diagram before; thanks for the idea.

The sensors are thermistors I think; the two wires are brown and white and the system is Eberspacher, if that helps? I'd prefer to switch them both just to avoid any complications as the rest of the system is complex.

[Simpo Two]

The switch is in the saloon so can be normal nice-looking one.

I need to be able to run a wire from the switch and link it in to the two sensor leads somehow so still a bit stumped.

[Simpo Two]

Thanks for the ideas so far... it might help if we start with what's facing me... this is how it looks:



'Feeds and returns' is getting too complex for my liking (I don't know which is which and the electronic controller might get confused by spare wires hanging about). Hence my desire to switch both wires. I think a DPDT switch has six pins.

As you can see I just need to cross the hole in the middle

[Simpo Two]

I still don't understand it but have a

[Simpo Two]

eliot said:

The drawings are correct. o/p the reason you are struggling is that you only have two wires from your switch - for any of the suggestions to work, your switch needs to be located where all your wires converge or you need extra wires leading to your switch location.

That's it exactly - the sensor wires (would) converge in an area under the helmsman's seat which is inaccessible. The physical layout side of it is actually very tricky, and not something I can easily convey!

[Simpo Two]

h8tax said:

The diagrams by HaplessBoyLard and Smiler are correct - unfortunately the one by ctdctd wont work (sorry - unless I am missing something?)

I think it would if you crossed over the left hand contacts...