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Started By
Message
Simple diode question in a circuit
Posted on 9/13/16 at 8:46 pm
Posted on 9/13/16 at 8:46 pm
I want to make a circuit where a action happens when given an input by a relay. I would also like the same action to happen by a switch press without back powering the circuit.
A 10a 12VDC circuit.
Would just using a simple 10 amp diode on the leg from the switch to the circuit not allow power to flow back through the circuit?
It's a reverse camera that comes on when the reverse light energizes it's relay. I would also like to turn on the relay from a switch without the reverse lights coming on.
I have a hitch camera, and a high mount reverse camera. In reverse the radio gets the hitch camera and the parking lines appear on the rearview monitor. So I have two reverse screens in drive, the rearview monitor gets the rear image and the radio goes back to being a radio but when parking I would like to be able to leave the cameras on.
A 10a 12VDC circuit.
Would just using a simple 10 amp diode on the leg from the switch to the circuit not allow power to flow back through the circuit?
It's a reverse camera that comes on when the reverse light energizes it's relay. I would also like to turn on the relay from a switch without the reverse lights coming on.
I have a hitch camera, and a high mount reverse camera. In reverse the radio gets the hitch camera and the parking lines appear on the rearview monitor. So I have two reverse screens in drive, the rearview monitor gets the rear image and the radio goes back to being a radio but when parking I would like to be able to leave the cameras on.
3
Posted on 9/13/16 at 9:43 pm to Napoleon
The relay would prevent back flow. If it's open no power can go across it. Same with the switch if it's open.
Would there ever be a case where the relay is closed with no power on its common? If so then you'd put the diode from the NO leg of the relay.
Would there ever be a case where the relay is closed with no power on its common? If so then you'd put the diode from the NO leg of the relay.
Posted on 9/13/16 at 9:51 pm to Napoleon
A graphical representation of the circuit would help. Depending on how I read the description, you may not need a diode, as you first response pointed out, if the relay you are talking about powers the camera alone.
Posted on 9/13/16 at 11:02 pm to mdomingue
Once I drew it out, I saw I either need two diodes or two relays. I think I have it solved.
Posted on 9/14/16 at 2:21 am to Napoleon
Put the cameras on a SPDT switch. I have aftermarket backup lights I run off of one
Battery hot
Off
Reverse On
Battery hot
Off
Reverse On
This post was edited on 9/14/16 at 2:24 am
Posted on 9/14/16 at 9:05 am to Napoleon
What you are doing should work. However, also add a flyback diode (google it). I would just do what Hammertime recommended and ditch the relay. There is no way that you need 10A.
Posted on 9/14/16 at 9:40 am to CoolHand
I guess an on off on switch would work, I just have a tone of relays and harnesses.
A flyback leading to the relay would be good too.
I may just go on off on. Don't need the ten amps, the circuit it's on also powers the other reverse camera, and the rear fog brake light.
I have a blank canvas here and get to try out all the geeky car electronics I wanted to try.
A flyback leading to the relay would be good too.
I may just go on off on. Don't need the ten amps, the circuit it's on also powers the other reverse camera, and the rear fog brake light.
I have a blank canvas here and get to try out all the geeky car electronics I wanted to try.
Posted on 9/14/16 at 10:45 am to Napoleon
Why not just run your 12v switched directly to the camera? This allows you to control the camera with the switch.
Then simply add the relay to your reverse light circuit, and power the camera from there in addition to through the switch.
Then simply add the relay to your reverse light circuit, and power the camera from there in addition to through the switch.
Posted on 9/14/16 at 12:00 pm to Napoleon
Get a hot wire coming from the battery for one side and grab either the wire coming off of the tranny or from the BCM for the other side. Need a multimeter and patience to find that one. Like I said, I did it for backup lights. It was a PITA without a wiring diagram
Posted on 9/14/16 at 12:23 pm to Napoleon
Why not do this? Relay in off position leaves camera hooked to 12v (rev)
Hit switch and relay switches camera path to 12v (ACC) which is basically 12v constant?
Posted on 9/14/16 at 1:44 pm to Hammertime
It's in a cargo van. I have the wiring diagram. For me the Black and green wire is reverse lights. I can tap into it in the headliner before the wire conduit starts.
Posted on 9/14/16 at 1:46 pm to CP3
damn, brilliant. Use 87a on relay to have reverse lights go to camera to power it. Use 87 for the switch. No diodes needed.
Posted on 9/14/16 at 2:21 pm to Napoleon
I have 3 circuits in my truck wired to function like what you want.
I used on-off-on switches to designate which voltage source supplies each relay. Did a circuit for Offroad Lights, Auxiliary Reverse Lights and interior accent lighting.
Gave me control to select between:
Auto-on with _____ function
.
.
OFF
.
.
Always ON (switched)
Here's some picts of the rest of the setup. Gets a little more complex since I wired in the LEDs on the switches to indicate which position it was in, but I love messing with stuff like this.
This post was edited on 9/14/16 at 2:27 pm
Posted on 9/14/16 at 5:43 pm to CP3
nice.
I also want to have a three way toggle (will use an on off on) so I can toggle the camera that feeds my rear view monitor. I have one above the license now and one I'm putting right above the hitch and another IR one that I am putting up high by the brake light.
I have a four channel dvr to record all four cameras on the van and then another dash cam that's independant, and may add side cameras later and one or two inside that would always be on.
Overkill. But I like tinkering.
I also want to have a three way toggle (will use an on off on) so I can toggle the camera that feeds my rear view monitor. I have one above the license now and one I'm putting right above the hitch and another IR one that I am putting up high by the brake light.
I have a four channel dvr to record all four cameras on the van and then another dash cam that's independant, and may add side cameras later and one or two inside that would always be on.
Overkill. But I like tinkering.
Posted on 9/14/16 at 8:20 pm to DoctorTechnical
Autocad. Made a layout and went to town. Need to redraw the relays but I don't really feel like it
Posted on 9/14/16 at 8:47 pm to CP3
I tried using Autocad once to draw out this really complicated panel that needed to be duplicated. Worked on it all day, and at the end of the day, the EE who asked me to do it said it was horrible and deleted the whole thing.
Yall some nerdy SOBs
Yall some nerdy SOBs
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