Relay Help, toggle between 2 HDMI inputs

tommymilan311

Joined Jun 3, 2015
9
Ugh, So first off, I'm new here and I'm not sure I'm posting this in the right spot.

I'm working on building a custom all-in-one computer, so I'm making a great deal of custom wire harnesses, etc. etc. If you wanna learn more shoot me a message, if you can do that on here.

Okay So here is my objective. I'm trying to have 1 19PIN output toggle between 2 19PIN inputs with a relay. So basically I'm going to have an internal graphics card primarily control the monitor. But I want to have a input plug on the outside on the case, so I can still utilize the monitor with a laptop. When I connect the laptop with a HDMI i want the +5V connector to trigger the relay and flip to the external input.

Does anything like this exist? Is there a way I can accomplish this only using one relay? Perhaps there is another method and I'm going about this all wrong.

LesJones

Joined Jan 8, 2017
3,110
Why not just use an HDMI switching unit such as this. There are hundreds more on ebay and probably Amazon.

Les.

crutschow

Joined Mar 14, 2008
26,857
A mechanical relay would not work well at HDMI frequencies.

tommymilan311

Joined Jun 3, 2015
9
So that only answers part of my question tho. I wont be able to use this alone because it will be built in behind all the panels. So I'll still need a way for this to sense the external USB and at least tell this to make the switch.

tommymilan311

Joined Jun 3, 2015
9
I've been noodling this for a little bit. And to be clear, I'm mostly ignorant when it comes to electrical components. I'm a Mechanical Engineer, so generally speaking I can read cut sheets, schematics, and I can sold and make all the mechanical connections. But when it comes to components and things I need, I know what I'm looking for mostly exists, but I'm not sure terminology or what to call things.

I've been trying to find some pics of boards, even though I'm only going to be using a 2 output, I found this picture. Would I be able to remove the button and replace it with some leads from a relay (or another switching component as it was mentioned a mechanical relay may not be the best use for this application.)

Because the button this button just switches from port 1 to port 2 with a push and release, I'd have to assume I'll need to send a signal when I plug in the external HDMI, and i'll also have to send a sense when it gets unplugged, simulating the button getting hit. My thought is to use a relay with NO and NC connections, So when the relay sees the 5V sense from the HDMI, it clicks on, simulating the first button press in order to move to port 2. When it loses the 5V sense from the HDMI, it clicks off, simulating the 2nd button press in order to move it back to port 1. Yes?

tommymilan311

Joined Jun 3, 2015
9
So I'm really trying to figure out a solution that will automate this switch. I'm not dead set on a relay or really any technology to do this. Just cost effective.

LesJones

Joined Jan 8, 2017
3,110
If there is only one of the HDMI sources powered up that input will be selected. If both are powered up then every press of the button switches between inputs. I think this is probably the same as the one in the link.
It looks the same but I bought this from a supplier in the UK. The push button and the LEDs are easy to connect to but I think it will be very difficult to solder wires in place of the HDMI connectors. I would suggest buying short HDMI extension cables if it has to be mounted inside the unit you are building. I think it would be easier just to mount it on the back of the unit.

Les.

tommymilan311

Joined Jun 3, 2015
9
The plan isn't to solder in wires for the HDMI pins, I'm going to use a breakout board for the external device (input 2). and use a HDMI plug to the switcher rather than try to remove the input and try to solder the wires directly to the switcher board, it just seems like too much busy work that really isn't going to give me any advantage.

I think I should be able to use a time delayed relay in order to simulate "pushing the button" when I connect something in input 2, and give the switcher time to read the connection. I want this switch to be automatic (not physically hitting a button) because I want this buried in the case, and I'll be using input 2 100% of the time I have something plugged into it so I'm not worried about switching back to input 1 until I unplug input 2.

I've learned with these that I will not need a 2nd hit of the button when I disconnect input 2 because the switcher will sense that and automatically flip to input 1. Input 1 will always be connected because that connection is done internally, connecting the internal computer GPU to the monitor.

I hope this makes sense. I'm trying to be as descriptive as possible what my end goal is, but I often talk in circles.

tommymilan311

Joined Jun 3, 2015
9
If there is only one of the HDMI sources powered up that input will be selected. If both are powered up then every press of the button switches between inputs. I think this is probably the same as the one in the link.
View attachment 206619It looks the same but I bought this from a supplier in the UK. The push button and the LEDs are easy to connect to but I think it will be very difficult to solder wires in place of the HDMI connectors. I would suggest buying short HDMI extension cables if it has to be mounted inside the unit you are building. I think it would be easier just to mount it on the back of the unit.

Les.
Hi Les,

Do you actually own the Board in this picture? and does it happen to be this one:

https://www.amazon.com/C2G-Cables-4...o+Switch&qid=1589303785&s=electronics&sr=1-3?

mcardoso

Joined May 19, 2020
193
A more “industrial” version of this would be a KVM switch. They are usually mounted in a server rack, although small versions exist. They do have units that can be controlled remotely, either by software or hard wired inputs.