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LED indicator for A/V selector Answered

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Hi! A while ago, i made an A/V selector, and it worked quite well. It had a small design issue, which is, having the ports at the front, where the switches are, and I want to upgrade it a little bit. The idea is, put on the front the switches with a LED on each input, and when I switch the selected input, the selected LED will also light. I've been looking around, and the A/V voltages are around 1 volt. The switch I have, it can handle 3 circuits at the same time (Video, Left and Right) but it has 3 rows as a conmutator or something. The thing is, i need your help in order to connect the LED. I've been thinking about using the unused row of the switch, but I don't know how, or, place a transistor when the Video input comes across the switch, but I don't know what kind of transistor will do.

Thanks in advance

I attach a diagram of what is now, with 5 inputs, showing only 2 of them, to have a brief idea

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Downunder35m (author)2017-11-05

It won't work as easy as you want it to as any addition to the signals will cause problems with picture quality.
But there is a simple "workaround" to the problem at hand, which I used years ago when I needed to get feedback from microswitch positions.
I assume you have the standard slider-type-selector switch.
Meaning it has three different positions which are slected by pushing it around - not a knob or "on-0off" flick type switch.
You can cut a piece of thin plastic to act as a repeater for another switch - even turned 90° to hide it all on the inside of the box.
Plastic strip has two matching holes for the switch pin you operate with your fingers.
When you select a channel the slider will also push or pull the other switch.
From that second switch simple wire some LED the way you like it.
It is cruicial not to have too much play in the holes to avoid the problem of not getting proper contact.

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jimmytvf (author)Downunder35m2017-11-06

The switches I put are the ones with a lever, not sliders. As far as I know, transistors as they receive any voltage from the base, it acts as a relay, and i guess that it won't cause any troubles with the image. I forgot to mention that, the LED will be powered from another source (let's say a phone USB charger or something like that). I've been told that making such a selector is a huge quality loss of image and, I've got to say, it is good as always, didn't notice the difference. Maybe i will go ahead and test the results as well. I'll make an ible too.

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Downunder35m (author)jimmytvf2017-11-06

If that would be the case then SV switches with indicator lights would have a massive amount of electronics inside and a huge price tag outside ;)
The transistor interferes with your signals for the video ;)

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Josehf Murchison (author)2017-11-05

Use 4 pole switches.

3 for the A/V and one for the LED.

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user

I've thought of that too, but i have to buy all the switches again.:D

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I think new switches would be cheaper than building comparator circuits to turn on the LEDs.

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jimmytvf (author)jimmytvf2017-11-06

Maybe i should do that, as i want to add even mote inputs as i have now... Thanks for refreshing me the idea, was way long in a closed drawer on my mind

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