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Two Triggers, One Output

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=146507
Printed Date: September 18, 2021 at 7:49 AM


Topic: Two Triggers, One Output

Posted By: kniggt3136
Subject: Two Triggers, One Output
Date Posted: October 20, 2020 at 5:33 PM

Hello everyone. Im trying to install two side view cameras to my lcd rear view mirror. The rear view mirror has two input with one trigger. One of the video input is already taken with rear camera. I need to connect the two cameras to second video output.

My issue is connecting the two trigger cables from dash cams to the trigger cable from rear view mirror.

I tried it by connectting all three cables but ended up having the mirror showing both sideways camera video distorted.

My plan is connect each camera to delay switch, so when it receives the signal let say from left turn signal it would send 12v to turn on the camera and also connect the relay switch that would send 12v to trigger cable of the mirror. Im going to need two delay switch for each camera and two relay switch. I need to know how do I go about connecting both relay switches to one trigger cable.

Thanks



Replies:

Posted By: i am an idiot
Date Posted: October 20, 2020 at 7:13 PM
You wrote:   I need to connect the two cameras to second video output.   Did you mean second video input?

I am guessing that the only trigger is what switches from the video input to the rear camera input.
Are you wanting the side view only to come on when your turn signals are active?




Posted By: kniggt3136
Date Posted: October 20, 2020 at 8:37 PM
Sorry, yes my second video input.

I only want them to come on when i put the turn signal on.




Posted By: i am an idiot
Date Posted: October 20, 2020 at 9:49 PM
Build this twice, once for left and once for right

On the left one, the 12 volts out to turning lamp needs to power the camera.
On the right one that wire needs to power the camera and also power 86 of a third relay.
Ground 85 of the third relay.
You will need to get some RCA cables and strip them to expose the center conductor and the outer connection, (the Shield). You need 3. One will go from third relay to the video input at the mirror. The other 2 need to go to the cameras.

Twist the 3 shields together and solder and insulate them.

Following are instructions for the center conductor of the RCA cables.
Mirror one to terminal 30 of the third relay.
Left camera to 87A
Right camera to 87




Posted By: kniggt3136
Date Posted: October 20, 2020 at 10:59 PM
SO I need in total 3 relay switches and 3 RCAs cables ?

Relay 1 ? is for the left camera and relay 2 is for the right camera, while relay 3 takes input from the other two relays and send it to the mirror?

What cables do I need to connect to relay 1 and 2 ?

Since one of the input of the mirror is connected, the RCA cable going from the relay to the mirror's second input right? what about the trigger cable of mirror. The first input is always on, how will the mirror know to switch over from input one to input 2?

Here what I got from your explanation

Relay 1

Pin 30 - ACC 12V
Pin 85 - Ground
Pin 87A - nothing
Pin 87 - Power on Camera on the left side
86 - Left turn signal

Relay 2

Pin 30 - ACC - 12V
Pin 85 - Ground
Pin 87A - nothing
Pin 87 - Power on Camera on the Right side
86 - Left turn signal

Relay 3

Pin 30 - RCA to Mirror
Pin 87A - RCA to left camera
Pin 87 - RCA to right camera
Pin 85 - Ground
Pin 86 - Connected to right turn signal




Posted By: i am an idiot
Date Posted: October 21, 2020 at 11:51 AM
If it is the mirror I am familiar with, the only thing that needs to switch is the reverse camera. From what I remember the video input is signal sensing. When it sees video it turns on.

With the mirror powered up and no signal on the input, does it display a blue screen? If not, we are good.

Relay 1, 30 to camera.
Relay 2 30 to camera and 86 of relay 3

87 on 1 and 2 go to accessory power.

86 on relay 3 connects only to output of relay 2. Not the turn signal


The terminal that is labeled 12v output to turning lamps goes to the appropriate camera.




Posted By: kniggt3136
Date Posted: October 21, 2020 at 12:14 PM
The rear view mirror is connected to a second cámara that shows the back it doesnt act as a reverse camara. When I turn on the car the mirror shows the back cámara. This is the first input.

I want a relay system that when I select right or left turn signal it would send a signal to the cameras trigger cable that will switch from first input to the second and it willshow that cámara on mirror.




Posted By: i am an idiot
Date Posted: October 21, 2020 at 12:38 PM
Unplug the camera from the input. Power the mirror up. Does it show a blue screen with nothing connected to either video input?

The trigger wire switches it to the other input. Camera input. If it does not display a blue screen, we are good.




Posted By: kniggt3136
Date Posted: October 21, 2020 at 12:41 PM
When both inputs are disconnected and mirror is on both screens are blue. When I put a 12v to tbe trigger it switches between input 1 and 2. After taking 12v off then it goes back to first input.




Posted By: i am an idiot
Date Posted: October 21, 2020 at 2:32 PM
What is the make and model of this mirror? It has 2 separate displays inside the 1 mirror?




Posted By: kniggt3136
Date Posted: October 21, 2020 at 2:34 PM
Brand: BOYO VISION

BOYO VTM700M - Clip-on Rear-View Mirror with 7" TFT-LCD Backup Camera Monitor




Posted By: kniggt3136
Date Posted: October 21, 2020 at 10:44 PM
I was thinking over and I think 4 relays will do it.

Relay 1

86 - left turn signal
85- ground
87A- nothing
30 - ACC
87 - Power on left camera and connect to pin 87A from Relay 4

Relay 2

86 - Right turn signal
85- ground
30 - ACC
87A- nothing
87 - power right camera, connected to pin 86 of relay 3 and pins 86 and 87 of relay 4

Relay 3

86 - receives from relay 2
85 ground
87a- RCA to left camera
87- Rca to right camera
30 - Video input to mirror

Relay 4

86 - receives input from relay 2
85- ground
87a - receives input from pin 87 from relay 1 that will go to pin 30
87 - receives input from pin 87 from relay 2
30 - connected to trigger cable of the mirror.


So when I click on the left turn signal in will go to relay 1 pin 86 sending 12V to camera and 87a of relay 4 that will go to pin 30 of relay 4 causing it to trigger the mirror. The camera will send video to pin 87A of relay 3 going to pin 30 of relay 3 going to the input of the cable.

Now when i click on the right turn signal it goes to relay 2 causing pin 87 of relay 2 to send 12V to pin 86 of relay 3 and 12v to pins 86 and 87 of relay 4, it will also send 12V to camera which would send video to pin 87 of relay 4 that would send it to pin 30 of relay 3 which would send video to input to the camera. As stated before pin 87 of relay 2 will send 12V to pins 86 and 87 of relay 4 causing the switch to close causing 12V to go the trigger cable of the mirror.


Let me know what you think.




Posted By: i am an idiot
Date Posted: October 22, 2020 at 7:12 AM
I will look at it and evaluate this evening.




Posted By: eguru
Date Posted: October 22, 2020 at 7:39 AM
You can use 2 small DPST or DPDT relays as per photo.
Don't go oversize on the relay contact current ratings as they don't handle video signals very well.posted_image




Posted By: kniggt3136
Date Posted: October 22, 2020 at 8:09 AM
Do you think you can find a video on youtube that will show what i need to do RCAs cables to connect them to the relay?

But do you think may way will work?




Posted By: eguru
Date Posted: October 22, 2020 at 10:18 AM
Two general purpose relays like this are all you need plus 2 cables with RCA M/F connectors.

https://abra-electronics.com/electromechanical/relays/pcb-mtg-1a-2a/rdp-145-mini-dip-relay-12vdc-1a-dpdt-rdp-145.html

Cut the cables and use the female ends to connect to the RCA plugs from the 2 cameras and wire the center conductor to each of the two relays.
Use the male end of the cable to connector to your mirror and wire the center conductor to the junction of the 2 relay contacts.

The outer cable conductors just get soldered together.





Posted By: kniggt3136
Date Posted: October 22, 2020 at 1:37 PM
Base on the below drawings can you write what cables i need to connect to each relay. Using relays for the first time.posted_image

Taking relay 1

A1- Left turn signal
A2- 12v from battery
A3 - Empty
A4- 12v to the camera and 12v to trigger
A5- ground
A6- rca cable from camera
A7- empty
A8- video out to mirror




Posted By: eguru
Date Posted: October 23, 2020 at 7:23 AM
You need to wire the relay coils directly to the turn switch (not to the pulsing 12V to the bulbs). On most vehicles activating the turn switch grounds the input to the BCM so that is the way I have shown it in the schematic. Meter your switch to verify that it is switching ground and not 12V.

btw. You might consider leaving the 2 cameras powered up continuously because there may be excessive delay for them to power up properly and stabilize each time you apply the turn switch.




Posted By: eguru
Date Posted: October 31, 2020 at 7:48 AM
So did you get your project working successfully with the help you received from the members?
It is always nice for us to get feedback after expending energy to provide help.





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