Connecting rear camera in car with a switch

[Starway]

I am trying to wire my reverse camera with a switch so I can have it on all the time or off all the time until I reverse. Is this possible how would I wire the switch? And what switch would I need. The camera only has positive and earth. Would I take power from reverse light and constant power and then switch them somehow so that I can have 12v+ all the time or only when reverse lights come on. / any help much appreciated . James
 

‘At the moment I can either get it to stay on all the time with permeant live or through reverse light , but I want the ability to switch it on when I’m not reversing ? 

Thanks

’james 

 

[Geoff1946]

You need something like the illustration here. Connect your camera feed to the centre terminal, a permanent live to one side terminal and the reverse light feed to the other. Centre position is then OFF.

The switch I've shown id double pole; you only need to use one side.

 

[Geoff1946]

Had a further thought on this. Do you really want an unconditional OFF?   i.e the centre switch position as described above.

I'm thinking partly about the need to run two wires from the back of the vehicle to the front.  You could switch between ON and ON when reverse selected with one wire and a changeover relay at the back.

Use any normal switch to supply a wire to the back. Get a changeover relay and connect the switched wire to the coil and to the normally open contact. Connect the normally closed contact to the reverse light circuit and connect your camera to the relay common. The relay coil will also need an earth of course.

If you like the idea but can't follow my description let me know and I'll sketch it out.

 

[Starway]

Hi ,

Thanks a lot for all your help, that’s really informative. And thanks for your time to write to me I really appreciate the help. 

I would just like to point out that the reverse camera can be powered at either end of the wire . As it has a power cable that runs the entire length of the rca video cable so on one end is a video cable and power wire that goes to the head unit side and the camera side has a power and earth and camera obviously

 At the moment I have it hooked up in a very cowboyish way that works. I have actually powered it from the head units own switched ignition power by splicing into it from that side instead of the camera side, and mixing the pink wire from the head unit that detects the 12v power and then turns the head unit into a monitor. It looks terrible in wiring and must be bad somehow for the electronics but it works. I just thought I should add how it’s hooked up at the moment. So I can get power from the front of the vehicle but unfortunately they didn’t run an earth to the head unit side as well so I have to hook up the earth near the camera in the boot which I have done. But I have left the other power cable from the camera side just unplugged as I get my power from the power the headunit receives on switches ignition. .

now that may be pointless for you to know but it also might help you realise the level of rubbish diy electronics I’m dealing with here and how it’s currently hooked up. If it helps I can send you a photo of how the cable is on the product on both ends if you don’t understand my description of it with the power lead that runs with the rca cable.. 

Your idea sounds great and probably will be my solution at its best although I was thinking it sounded a bit complex for me as I have never used a relay before. I have heard something about using a switch and 2 1amp diodes twisted together at 1 end and this will simply allow me to switch the power from constant to only on when reverse light is on and the point of the diodes was to not let the car reverse lights turn on when I turn the camera on and check it. /

could there be be a simpler way than you described ? If not I’m happy to go with your idea but I would definitely need need a drawing to help me through it with basic information and really hand holding to an extent. 

‘Thanks again for your time 

james 

 

[Geoff1946]

Actually the two diode suggestion is a good one and probably as simple as it gets. 

It's the same purpose I was suggesting the relay for but both cheaper and more elegant.

 

[Sidewinder]

@Geoff1946, this would work?

https://uk.rs-online.com/web/p/non-latching-relays/9156635/

 

[Starway]

Hi,

ok great I’m glad we have found some sort of solution, only problem being is that I am stumped in wiring it up properly. I think I understand but I’m not sure really. 

So so I order to have the switch working as I want I need to get 2 1amp diodes ? As I’m guessing the reverse lights and camera won’t each take more than 1 amp. 

I would twist the cathode sides together and wire the monitor input to that twisted joined side. 

I would wire 12v from the reverse lights power + to one diode end 

I would wire a permanent 12v + ignition wire to the other diode end 

I then then would connect the switch in between the permanent supply before going to the diode ? In line so that it just breaks the circuit from the perm at live from reaching the diode ? 

‘’Is it that simple ? Could you maybe provide some sort of diagram with the diodes, sorry for so many questions and so much rubbish which must be so basic. 

I just want to get it right and learn something 

thanks again for your time 

james 

@Geoff1946, this would work?

https://uk.rs-online.com/web/p/non-latching-relays/9156635/

View attachment 10669

Im still confused from the diagram , that looks amazing but to me it’s slight complex > could you explain it with my wires I have and what to connect ? 

 

[Sidewinder]

I don’t know what wires you have in your car.

 

[Starway]

 

Sorry for the terrible drawing but do you think this would work ? 

 

[poni]

No, the reversing light will come on every time you override the reversing switch 

it would be better to run the camera/monitor feed cable to the common of the switch ,then to L1 on the switch the permanent live  and on L2 the feed from the reversing light. don't forget to fuse both feeds 

 

[Geoff1946]

@Geoff1946, this would work?

https://uk.rs-online.com/web/p/non-latching-relays/9156635/

View attachment 10669

Yes. That's what I was trying to describe in words, except I had relay 87 connected to 85. Saving the wiring and your F3.

However, I thought the alternative suggestion of using diodes (or even just one perhaps) was simpler.  I don't think the half volt or so lost in the diode would affect the camera. 

 

[Geoff1946]

Here the schematic for using just a diode. Sorry, I can't do proper computer drawings.  

 

[Starway]

Thanks guys I’m still getting to the bottom of this then,

Sorry Geoff I’m such a newbie ,could you explain the drawing with the 1 diode in more detail as you can see the wires I have now. 

Im not sure if I understand what the circuit parts are like the circle with a cross ? Could you draw something like I have with the correct wiring? I know this is asking a lot but I feel like it would be the quickest way for me to understand. I’m trying to get my head around your circuit but with no one to talk to about it I’m stumped at the simplest of things. I’m a musician so I have zero electrical knowledge just diy get by stuff. 

‘’Looking to learn but obviously need my hand held 

 

[Starway]

Just to learn something new, could this type of switch work?  Replace PSU and battery with reverse light and 12v permanent?  Sorry im just trying to learn ! I just thought that if the switch can switch to reverse light or permant power then the lights wouldnt come on when I flip the switch to permanent?  

 

[Geoff1946]

This would be easy if we were sat together with a fag packet to draw on!!

I think you more or less have it with your sketch.

The whole point of  a diode is that it will only conduct in one direction. The way I've drawn my scheme that diode will let current flow from the reversing light to the camera to activate the camera. It won't let power applied to the camera from another source flow to the reverse light.

It's the diode you have marked as 5amp on your sketch, PROVIDED it "points" the right way.

The second diode on your sketch isn't actually needed, though it would still work, again provided it points in the direction of current flow, i.e. towards the camera.

The reason the second one isn't necessary is that there is no occasion when current would try to go from the camera back towards the over-ride switch so the wire can just go direct.  

 

[Starway]

Thats great thanks alot Geoff, I just wonder why the switch idea woukdnt work with 2 power sources and 1 output?  Surley if I plug it in to a switch like this  then it would not send power to the reverse lights when I activate overide? 

Surely the switch that I posted could cut the connection between the camera and the reverse lights when I switch to permanant source without any leakback to the reverse lights. Makes sense in my small brain 

 

[Geoff1946]

Thats great thanks alot Geoff, I just wonder why the switch idea woukdnt work with 2 power sources and 1 output?  Surley if I plug it in to a switch like this  then it would not send power to the reverse lights when I activate overide? 

Yes I think I know what you mean and yes it works in principle, but I was trying to focus on solving your initial requirement as simply as possible. There are frequently many ways to wire something but the simplest is often the most reliable and cheapest too.

 

[Starway]

Ok so to be clear are we saying that a simple switch solves my solution and no need for diodes ? Just a switch like i posted with 2 power inputs and 1 load. ? Isn’t that the simplest ?    That way I don’t need diodes ? And since I need a switch anyway does it not make sense for me to just use a switch ? Will I get leakback to the reverse lights with the switch and suggesting. Is this switch diagram correct except I just swap the inputs with outputs and it will work ? 

Ok so to be clear are we saying that a simple switch solves my solution and no need for diodes ? Just a switch like i posted with 2 power inputs and 1 load. ? Isn’t that the simplest ?    That way I don’t need diodes ? And since I need a switch anyway does it not make sense for me to just use a switch ? Will I get leakback to the reverse lights with the switch and suggesting. Is this switch diagram correct except I just swap the inputs with outputs and it will work ? 

Would I need the ground in this switch or just connect up the positives m does this even work, or will I be faced with the same leakback to the reverse lights 

 

[Geoff1946]

If you look back to my very first answer and compare the words with your switch drawings you will find they are the same, except that I specified a centre OFF switch, which is purely optional. 

The other suggestions are intended as ways to simplify the installation.  Your choice.

 

[Geoff1946]