I just replaced the illuminated momentary AV switch in my wife's Champion JadeFire (it came loose and had to be rewired, so I took the opportunity to change the color as well) and want to pop it onto my Warrior Acolyte.

I know I can't just slap a momentary switch on this circuit because it will basically act as a dead-man switch but I don't want it to actually function. I just want it to light up. So I've taken the dummy button out of my Acolyte and realized that I can't just wired in the LED because it needs a resistor.

"Okay," I thought to myself. "I'll just get the dynamic resistor from TCSS and that will be perfect. But then I actually look at the specs of the switch they sell at TCSS and compared it to the labelling on the switch in my hand. The TCSS product page lists the forward voltage as 3.0V. The switch in my hand has "3.3V" written on the side.

I don't know just enough about electronics to get myself in trouble. I'm wise enough to know that if something isn't EXACTLY THE SAME, I should double check and learn about it before I wire it up in exactly the same way.

So the first part of my dilemma is: should I treat this as the same switch? Why or why not? What do I need to learn before proceeding to make sure I don't have the same confusion again about a different component?

Here's the next bit.

Both my wife's purple 12W LED unit and my amber 12W LED unit have resistors on them. They're obviously different because different colors are safe at different currents. Again, the Jade is a Champion and the Acolyte is a Warrior. It was my understanding that soundboards all provide current control for at least the main LED and some for accent LEDs (such as the one on the AV switch) as well. The switch I pulled out of the Jade didn't have any resistor on it (I therefore replaced the new switch without a resistor) but the main LED unit has.

Clearly there's something I don't understand. If soundboards provide current control for the LED module (thereby precluding any need for resistors on the module itself), then why does the LED module have a resistor? If the soundboard DOESN'T have such a feature, why doesn't the AV switch have a resistor to keep its LED from burning out?

I guess it's entirely possible that the board acts as a resistor for the switch and not for the main LED but that seems unlikely to me.

Most boards have pads that are made for accent LEDs and they regulate current. Main LEDs aren't always regulated and even if they are, it's recommended to resist them to be safe.
If your switch LED or accent LEDs are run from separate pads than your main LED, they are regulated.

You could still use a dynaohm resistor for that switch you have. That's what the dynaohms are for. They accept a wide voltage range and provide constant current. If you want to use a normal resistor for some reason, I'd use a 22ohm 1/8W resistor and you should be fine. It's good to have some normal resistors on hand because occasionally you'll have accent LEDs that need to run below 20mAh and you can't do that with those 20mAh dynaohms.
I had some green accent LEDs that would start turning yellow on a dynaohm. I had to bring it down to like 15mAh for it to look right.

That answer your questions? Sorry I gotta go to work. I'll check back later. lol

That does solve my problem but I'll still have to ask again next time I need a resistor. I'm trying to learn so I can stop depending on the forums to solve all my problems for me. I'm very grateful for the solution but I'd still like to know how to find it myself next time.

Also: do I care that the swith from SF is 3.3v while the one from TCSS is 3.0v?

I suppose I'll have to perform major surgery on the Jade to figure out what the soundboard actually does, since I can't visually inspect it without cutting all the wires (then lengthening them s I can reinstall it).

thorvindr wrote:
You only need to worry about the switch Vf if you're using regular resistors. If you use a dynamic resistor, it doesn't matter; therein lies the beauty.