I need something where it has two inputs and one output, so either (1) can be triggered and activate the output or (2) can be triggered and activate output but not backfeed into the opposing trigger source. (If possible asbestos trigger to also block all output, since one trigger source is automatic id like to be able to block the trigger output of that at times)
So a switch is one trigger, automatic trigger, and option to block the output at times i want when the automatic trigger is powered.

 

Your question is not clear. input and output of what? Audio, video, power? More detail about what is being switched and power levels would help. What is to do the "switching". Is the 12V in the title the power being switched, or the voltage used to do the switching?

 

Your question is not clear. input and output of what? Audio, video, power? More detail about what is being switched and power levels would help. What is to do the "switching". Is the 12V in the title the power being switched, or the voltage used to do the switching?

Sorry I don't really even know how to ask what I'm trying to do I'm not good with this stuff, but both input triggers are 12v positive power and the output needs to be positive 12v power also.
So the one 12v positive input is automatic, it comes on when a separate sensor is activated, the other 12v positive input would be from a switch. I don't know what i need to control this ( a relay or something?) To put a single positive 12v output when either trigger is activated but not back feed into the other un active trigger, I'd possible I'd like to be able to ad another switch of some sort with either 12v - or + to stop all output even when one of the inputs is triggered, so if the auto input is triggered but i don't want to receive output from (?) Device is can switch it so it wont.

 

Would this work for you?
The two diodes D1 and D2 provide isolation.
Stop switch shown open, no output.

 

Would this work for you?
The two diodes D1 and D2 provide isolation.
Stop switch shown open, no output.
View attachment 344642

Im gonna try this and see if I can make it work for my application, thank you for helping even tho I made a seems simple problem into something hard. Like I said I'm brand new to this stuff just trying to learn as I go.

 

How much current is being switched in order to select the proper size diodes?

 

How much current is being switched in order to select the proper size diodes?

It would probably only be around 10 amps.

 

Recommend this Diode
At 10 amps this diode will dissipate appx 5 watts and need to mounted on a heatsink.
There is also appx 0.5 volt loss through the diode.

 

Recommend this Diode
At 10 amps this diode will dissipate appx 5 watts and need to mounted on a heatsink.
There is also appx 0.5 volt loss through the diode.

Thank you!

 

Recommend this Diode
At 10 amps this diode will dissipate appx 5 watts and need to mounted on a heatsink.
There is also appx 0.5 volt loss through the diode.

Just to check will this diode work with 12v dc?

 

Yes, it's rated to 60 volts and 20 amps.

 

Instead of separate diodes, use a 25A bridge rectifier like this, and bolt it down to the metal chassis for cooling.
This also makes mounting it all easier.

 

That bridge will work but does have twice the voltage loss compared to the schottky.

 

View attachment 344643View attachment 344644
Instead of separate diodes, use a 25A bridge rectifier like this, and bolt it down to the metal chassis for cooling.
This also makes mounting it all easier.

This will also work with DC power?

 

This will also work with DC power?

Yes. That is as long as the 12V signals are +12V.

 

Recommend this Diode
At 10 amps this diode will dissipate appx 5 watts and need to mounted on a heatsink.
There is also appx 0.5 volt loss through the diode.

For this diode does it have to be mounted in a specific way using the hole?

 

The tab with the hole of that diode is the "K"athode, as is one of the leads. If you use the diodes, they will need to be insulated from gnd, not just screwed down to metal for a heat sink. You can either mount both diodes to a heat sink and insulate the heat sink from gnd, (the heat sink then becomes the output) or use insulation kits for the diodes.

The bridge rectifier is a lot easier as you can just screw it down. I doubt the extra voltage loss wil cause any problems.

 

View attachment 344643View attachment 344644
Instead of separate diodes, use a 25A bridge rectifier like this, and bolt it down to the metal chassis for cooling.
This also makes mounting it all easier.

So with this i wouldn't connect anything here correct?

 

Yes, that is correct.
Using the bridge, just crimp spade terminals onto the wires and push them onto the 3 terminals. The "-" terminal is not used.

 

Throw in a couple of schottky diodes to keep the voltage drop low. If you want dimming when both are on, that’s a whole other setup with relays or resistors and gets complicated fast. Just make sure the diodes can handle the current.