Hi! I want to test how my caps look on the led switches I got today, but I'm unsure about the led voltage. (Don't want to burn any out). I couldn't find any info on the correct voltage for them. Got my bench psu hooked up, I got them glowing but I don't know how bright I should go. The dimmer setup tells us it's 4 leds in series from 12V with a 1 ohm resistor per series. What voltage does that make for one of them? 12V/4=3V seems high? Can they withstand that much voltage? How much does the resistor affect it?
I just want to know as I might end up wiring them differently :)
I used a 10k rotary (leftover from 737 throttle build) and wired banks of 4 LEDs in series (as per Karl’s wiring diagram).
Each set of 4 (17 sets and 1 LED left over I think it is) has only two wires + and -
All of the - get chained up together and go to the - of the PSU. All of the + get hooked up to the middle pin on the rotary encoder. Then hook 12V up to the left or right pin on encoder and there you have dimmable LEDs that will not blow.
The encoder slots into the bottom right of the screen. It’s for screen brightness IRL but hey :-)
Hello, I have just sacrificed one of my tactile led switch's for testing:
There are two different types of LED's fitted to the tactile switches i have. There are the crystal clear version which i only have 3 or 4 left. Not used these and i think they came with an arduino kit.
The ones from eBay have an opaque haze to them. These are the ones i just tested.
2.6v just visible
2.8v med brightness
3.0v high brightness
3.1v super bright 0.1mA
3.2v Super bright 0.2mA
3.5v Blown
If you really want to be safe, use a 47ohm resistor rather than 1 ohm.
Hello Karl, thank you for the answer! Just to clarify, I'm talking about the led microswitches for the 3D printed FMC - but it was nice to get the specs for the KD2-22 too as I'm about to wire up the MCP any day now as well :) So my follow up question will be 😁, in your first paragraph are you talking about the FMC micro switch leds or the KD2s for the 3.2v at 20ma specs? But 3V seems to run them fine I agree. I'm not going to go higher.
The micro switch leds came in a small ziplock bag with no datasheet attached and I could not find one at any of the sellers, only measurement but nothing for the led voltage.
Hello, the data sheet indicates the are 3.2v at 20ma. 12v is not enough to fully run them at so I was happy with running them at 3v. Also, the buttons I have, already have a resistor in circuit as they should be powered by 12V.
Remember, there are at least 4 version of the Kd2-22 switch i know of. these are 3, 5,12, & 24V. I suggest you measure the resistance of the circuit which will give you a good what's inside, or refer to your datasheet that came with the switches. Using the datasheet provided, will give you precise and detailed info rather than my figures.
I hope that helps.
Kind Regards Karl