RF switch to turn off video and audio transmission of HDMI input - Page 1
Forum section: electronics / projects

author: stevesmithtx
author_rank: Newbie
timestamp: September 10, 2017, 03:23:06 pm
content: Hi all,I was sent this direction by youtuber aintbigaint clever, and I'm pleasantly surprised by what a lively community there is here! I am working on a project which involves delivering an on demand visual stimulus to children for research purposes. I am wanting to you low cost TV's with HDMI inputs (connected to an apple tv or something like that) and put some kind of rf module between the HDMI's to activate the picture and sound with the push of a button. Then when releasing the button, instantaneously kill the picture and sound without having the TV lose the connection to the HDMI source.My question...first, is if anyone knows if anything like this already exists?If not, does anyone know which wires on an HDMI you would need to have access to kill video and audio, but have it be instantaneously on once the connection was reestablished via the remote?I'm not incredibly technical myself so I'm looking for all the insight I can get. If it's a project you think you could do, I'd be interested in paying someone to help me out as well. Thank you!

author: flynwill
author_rank: Regular Contributor
timestamp: September 10, 2017, 03:40:38 pm
content: How "instantaneous" does it need to be? Given the complexity and overhead of HDMI, I would guess that you are looking at a second or two for it to recover from any interruption on the cable itself. My guess is you would be better off finding a way to get he software on the Apple TV (or whatever device you choose) to switch the video.Alternately let the TV do the switching, most have multiple HDMI inputs. You'll need two video sources, one with black/silence and the other with your program. Then use a universal remote to switch between the two sources.

author: pelud
author_rank: Regular Contributor
timestamp: September 10, 2017, 04:03:31 pm
content: My suggestion would be to find a TV that can accept VGA and use an HDMI to VGA adapter. The signals are easy to access on the 15 pin connector. The sync signals are separate from the red, blue and green signals, so the TV should hopefully stay in sync with the source as long as you only cut the color signals.You might even be able to find a cheap VGA switch box, or even a KVM switch, that has a button on it. It might not be fast enough, but you can usually find them for cheap so it might be worth a try.

author: Richard Crowley
author_rank: Super Contributor
timestamp: September 10, 2017, 04:38:59 pm
content: When you say "TV lose the connection to the HDMI source" you apparently mean that you want to switch BETWEEN your video/audio program material and "BLACK". (In order to maintain the synchronization). This done commonly in video production with a video switcher. Most of these are rather expensive ($1000 and way up) and don't seem to meet your requirement for "low cost".There are consumer HDMI switches that are "synchronous" so that they don't break the HDMI data connection when switching. Although they are also rather expensive (100s to 1000 of $$). Some of them may have a built in black generator, else you will need an external black generator which could be something as simple as a Raspberry Pi, etc.You did not mention what is the SOURCE of the video? If you are playing the video on a computer, consider that it might be easier to do this in software vs. hardware. Not really enough detail to make any better suggestions.Also not clear what you mean by "rf module"? Do you mean some kind of wireless remote control or something?

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 10, 2017, 05:38:39 pm
content: Not expensive at all. First one on an eBay search:http://www.ebay.com/itm/For-DVD-HDTV-PS3-1080P-3-Port-Switch-Splitter-Out-HDMI-Hub-Box-Cable-Adapter-US-/302444853601?hash=item466b1e3961:g:p~QAAOSwAPVZKSCDJust input black signal to one and the other the desired video.As far as the RF part, just use IR with an extender to a switch that costs a bit more with IR and a remote control.Such as:http://www.ebay.com/itm/3-Port-1080P-Video-HDMI-Switch-Switcher-Splitter-with-IR-Remote-For-HDTV-AD-/332300162864?hash=item4d5ea21730:g:5dcAAOSw42JZMiI8

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 10, 2017, 06:10:52 pm
content: Just get a Raspberry Pi or similar to use as the source.

author: Richard Crowley
author_rank: Super Contributor
timestamp: September 10, 2017, 09:45:09 pm
content: A primitive "crash switch" such as the one suggested by @Quarlo Klobrigney would probably do the job for more-or-less instantly blanking the video and audio. However, you would be stuck with the recovery time of your "very low cost TV" when you want to restore the picture/sound. In some cases it could be less than 1 second, and maybe that is good enough for your purposes (not explicitly specified).But the primitive crash switch does not meet your requirement of "without having the TV lose the connection to the HDMI source". Although we really don't know why you need that or what it means? Also not clear is the role of the "Apple TV or something"?

author: sokoloff
author_rank: Super Contributor
timestamp: September 11, 2017, 12:31:10 am
content: If you can do the VGA (RGBHV) thing, you can pick up some surplus Extron (or similar) switches on Ebay that would do the switching among sources (or to/from black) and some switch audio as well.Some of the Extrons are switchable by contact closure, which would get you simple integration to a button. Those should be cheap now.If you can go down this route, I can help you out further (advice for free, of course).If you absolutely need it to be HDMI and instant, it's not going to be cheap, unless you can find a display device that supports audio and video mute (and ideally RS-232 or ethernet control). Then your task would be to control the TV via ethernet/RS-232 in response to the button.

author: LaserSteve
author_rank: Super Contributor
timestamp: September 12, 2017, 05:03:03 am
content: Depending on the display, you may need a "EDID Ghost"Between the monitor and the video switch. This helps prevent delays caused by poorly written monitor firmware.Black Box inc. Makes good ones.STEVE