Reverse Camera + Monitor Reverse Light Tap

Discussion in 'Electronics' started by mbenz1, Jun 8, 2017.

  1. mbenz1

    mbenz1 Active Member

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    Hi Guys,

    This may be a long shot but hoping for some feedback for a 2005 C-Class Estate.

    The plan is to install a reverse camera near the License plate and a complimentary monitor on the rear headliner section so that it is in direct view in the rear view mirror when reversing and this also avoids sticking the monitor on the front dash in a premium interior.

    Questions: Would it be okay to connect the camera power supply to left reverse light wire and the monitor power supply to the right reverse light? Would this cause any overload on the circuit?

    Camera consumption: 120mA
    Monitor power consumption: 2W (no current data available for monitor)

    The reason why I want to connect monitor to reverse light and not a constant power supply is to avoid the Blue screen when camera is off.

    Also, I've been reading that the reverse light wire does not always have 12V so would I need a relay for both positive power connections?

    Any advice much appreciated.

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  2. OP
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    mbenz1

    mbenz1 Active Member

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  3. Ted

    Ted MB Enthusiast

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    Camera consumption: 120mA
    Monitor power consumption: 2W (no current data available for monitor)

    At 12V
    120mA is 1.44W
    2W is 166mA

    The two reverse lights are 21W each=42W

    So you are adding around 3.5 watts, which would be within a 10% tolerance and should be ok.

    Just ensure that the monitor does not have a surge current when it turns on.

    As a matter of opinion? I would say it is safe to add them.

    Edit: Oh, and don't use a relay unless it has a clamping diode (ore you use a diode) as the voltage generated when it turns off could damage something. A 1n4001 should be ok for this.
     
    Last edited: Jun 9, 2017
  4. OP
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    mbenz1

    mbenz1 Active Member

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    Thanks for your detailed reply...

    Having studied engineering my self the golden formula P=VI totally ran out of my mind ;)

    Not sure about the surge current so will have to check this out.

    Regarding the relay and diode, I hope the reverse lights have a healthy voltage (ideally around 12V) so I can avoid using a relay. Regarding the diode, I will need to find out if the circuit has it, if installing the relay is required. Any tips on finding the diode?

    So all in all, it is possible to connect the bits this way which is good and looking forward to this mini project.

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  5. Ted

    Ted MB Enthusiast

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    I think you can run it without a relay. Maplins will have the diode - 1N4001 or 4002 4003 etc are pretty much standard semiconductor diodes. Cost pennies. If the relay doesn't have one built in, I would absolutely use one. Connect cathode (white band) to the positive of the relay coil (sometimes marked W1) (by that I mean the connector that you apply a positive feed to energise) :)
     
    Last edited: Jun 9, 2017
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  6. OP
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    mbenz1

    mbenz1 Active Member

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    Just been doing some research on the surge current issue and this only seems to be a problem for the monitor/camera when turning ON so hopefully the circuitry contains necessary protection for this. Worse that could happen is a reduced lifetime of the camera and/or monitor if they do not contain surge current protection. As the kit can be bought cheap, replacing it would not be an issue...

    I will now check the voltage at the positive reverse light pin on the harness and see what the voltage is and order a relay and/or diode if required.

    Will keep this thread updated.

    Can anyone suggest a good splice connector for the wiring in these cars or would standard Maplin 8Amp 3mm wire diameter splice connectors be good enough?

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  7. Ted

    Ted MB Enthusiast

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    Yes, the surge current is only a possible issue on switch on. It win't damage the device, but potentially the current source (i.e.the SAM).
    Thinking about it, the surge current of two 21 watt incandescents will be much more than the monitor, so shouldn't be an issue.

    Don't remove a reverse light bulb to check for voltage as this will be detected as a bulb out and you will see a pulse rather than a constant supply as it checks for a resistance.

    I'll come in for some criticism here, but a 'scotchlok' type tap will be fine as long as it is inside the car.
    Not elegant, but quick, and simple.
    Other forms of wire tap are of course available :)
     
  8. exvolvoman

    exvolvoman Active Member

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    I fitted my reversing camera and monitor both wired to the o/s reverse light wire at the rear light assembly.
    This way they both only work when reverse is selected, no problem with bulb failure warning or anything else. This does mean running two cables to the front of the car, monitor power and camera feed.
    Not sure how good your view will be by looking at the monitor in rear view mirror...
     
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    mbenz1

    mbenz1 Active Member

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    I understand your point regarding the surge current. Its only 3.5 odd watts so not something to worry about.

    Re. checking voltage, indeed. I will use a splice connector with a free wire coming out of it and connect that free wire to the multimeter probe to check voltage. This would save me removing the harness and causing a bulb failure message, which can be a tricky one with these cars.

    Re. Scotch lock taps, yes, this seems the easiest for me as it doesn't require any soldering and my dad's old solder kit is no good either. I know the traditional solder + heat shrink is always the best :)

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    mbenz1

    mbenz1 Active Member

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    Thanks for sharing this on here and glad to hear connecting both feeds to the one reverse light wire works good also.

    Regarding the view, as my phone screen size is the same as the monitor size, I took a picture of the front of thr car to mimic a reverse camera view and then got my brother to hold the phone on the rear headliner section and the view was good in the mirror so hoping it will be the same with the monitor!

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    mbenz1

    mbenz1 Active Member

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    Got some splice connectors and 2m of 6 Amp cable just in case.

    Now waiting for the camera kit to come through post.

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    mbenz1

    mbenz1 Active Member

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    Update: got the reverse camera kit finally and have managed to connect it all up and all is working good and had a healthy voltage at both left and right positive terminal for reverse light so did not require a relay!

    It was tricky taking the wires from the reverse camera to positive reverse light terminal as on the Estate model there is a rubber hose carrying wires which connects the D pillar to the inside of the car and it is through this hose where the camera wires were fed through and it is a pain to get the wires across.

    I will take some pictures of final set up and display soon!

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  13. OP
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    mbenz1

    mbenz1 Active Member

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    Update:

    Just noticed the camera flickers about 4-5 times every 10 seconds when idling/moving in reverse. Sometimes it flickers at a much less frequency.

    Checked the reverse light voltage at idle and it was around 13.3 on the left (where camera is connected) and about 12.9 on the right (where the monitor is connected) and I also managed to check the voltage whilst the car was being reversed and the voltage was stable with a bit of fluctuations but not anything concerning - only a drop of about 0.02V. So voltages were healthy for the kit...

    I sent the seller a video of the reverse camera footage and they kindly have put a new camera in the post for me. So I will wait for the new cam and see if that solves the flickering.

    On the other side, because I have put the monitor on the rear headliner and the camera displays a 'mirror' image in the screen, the image is seen opposite to the actual scenery - so left is displayed as right and right is displayed as left, in the screen, via the rear view mirror. Luckily, I have learnt there is a Green wire within the camera cable which has the function to display a 'mirrored' image in the screen. If this wire is cut, the camera displays a non - mirrored image in the screen. So hopefully the Green cable will be easy to get to and I can get the image on the screen to show left as left and right as right.

    Will keep this thread updated.

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    mbenz1

    mbenz1 Active Member

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    Update:
    The new camera solved the flickering issue at last. Now the image is still and clear.

    Regarding the mirror image issue: Unfortunately, I could not get the image to display as 'non-mirrored', after cutting and swapping several wires in the camera cable.

    I understand there is no wire in the camera cable to mirror the image. So this leaves only the monitor now. I am sure the monitor is creating the mirrored image. I am not sure about its wiring and how it is producing the mirrored image so I have asked the seller to kindly ask the manufacturer for this detail.

    But all in all, a very good purchase and I am very happy with the job. Pictures below:

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    mbenz1

    mbenz1 Active Member

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  16. 4life211

    4life211 Active Member

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    Hey pal where did you get this display and camera? What is the name ?
     
  17. GLK

    GLK MB Enthusiast

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  18. OP
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    mbenz1

    mbenz1 Active Member

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  19. Ted

    Ted MB Enthusiast

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    Congratulations on getting it done :)
    Looks a treat!
     
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  20. OP
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    mbenz1

    mbenz1 Active Member

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    Thanks Ted and thanks also for your advice, spot on!

    The only thing that's bugging me now is how to get the non-mirrored image... I hope there is a solution.

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