How to Wire 1switch to 2 independent switches.. - Page 1
Forum section: electronics / projects

author: grindcorehippie
author_rank: Newbie
timestamp: May 11, 2022, 08:36:33 am
content: In my car I wired in a Front View Camera (Camera-A) that has it's own toggle switch (S-A) to manually turn it on/off, and has it's video displays on my Head Units Display. I also wired a Backup Camera (Camera-B) to it's own toggle switch (S-B), and then it's video displays on my rearview mirrors Display. Right now they are both manually and individually turned on/off with their own toggle switches, but is sometimes a hassle to have to turn each one on and then turn both off if I want them both on at the same time, but I do like being able to turn just one on when I want. So instead of have to turn 2 toggle switches on to have both cameras working at the same time, I want to add in a third switch (S-C) that would be able to turn on both cameras by just using it, but then still be able to use Switch-A or Switch-B to turn them on individually when I want to.I first tried to just wire Switch-C straight to both Switch-A and Switch-B by running a wire from S-C straight to the Load side of S-A/B so when it was toggled to On it would send power directly to both Cameras, and thought S-A and S-B would still work independently. But because S-C had a wire running straight to both, when either S-A or S-B gets toggled On, power just ends up running back through S-C and then to the other switch so no matter what both cameras get turned on..So I figured all I need to do is to make it so the two wires coming from Switch-C that run to S-A and S-B just need it so that they will let power flow from S-C to S-A and S-C to S-B when toggled On, but not be able to flow in the opposite direction when S-C is toggled Off where turning on Switch-A then lets current flow back to Switch-C and then straight to B or visa versa turning on S-B the sends power back to S-C and then to S-A..I thought that I could use a resistor on each of the two wires from S-C to S-A/B, but was informed yesterday that I mistook diodes for resistors and that I could use a diode on each wire to force power to only be able to flow in one direction so that it would block any power from flowing from S-A back through to S-C and then to S-B. Then I could use S-C for turning on both cameras at the same time, but then also still be able to use either S-A or S-B independently when I want to.So now where I'm at is that I can't seem to figure out what size Diode I would need to use for this when it's using a 14v+ source, or if I would need to add another component with a diode. I also saw somewhere that said there might be a different/better way to wire it that uses a different component like a Mosfet or something like that, I believe they said that using the mosfet would also be able to force current to only be able to flow in one direction, but I don't know hardly enough about mosfets besides that certain ones are made to deal with higher voltages and they're used in Audio Amplifiers. How do I figure out what kind of mosfet would work the best? Oh. a little kind of side note: the cameras only need 12v to trigger them to turn on, and my electrical system is supplying 14v+, so it has about 2v of wiggle room if any components cause a voltage drop.Any help/advice is appreciated!!! I hope I was able to clearly explain my situation and what it is I'm trying to accomplish. Just ask if more information is needed. I am also going to upload schematics of what I first did, and another of what I want to do. Please show mercy to my first drawn out schematics, I used new software on my PC and had to try to figure it out as I went. Any advice on drawing a better schematic is welcome! I will also try to get a few pictures of the actual Switches/wiring in my car before I have to leave for my day job.

author: themadhippy
author_rank: Super Contributor
timestamp: May 11, 2022, 10:02:35 am
content: 1 double pole double throw switch and 2 single pole double throw switches,no diodes or resistors needed

author: grindcorehippie
author_rank: Newbie
timestamp: May 11, 2022, 10:13:36 am
content: Here is a schematic of what I'm trying to accomplish. If there is a better/easier way I'm all ears! How do I figure out what Diode I would need to use?