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I got mine today in Maryland USA. I have to say i am pleased. I expected the housing to be plastic, but it seems to be metal most likely aluminum, with a what looks like PCB with the key-switch attached so you can solder some leads to it to make something work upon pressing a button. However not being an electrical engineer despite taking several engineering classes, I would have no idea where to start doing something like that.
I soldered some LEDs in mine and use it to click with light. Basically just to test the actuation points.
Where in MD. Do you still need yours? I'm in MD and could use a tester to decide my next keyboard. If you are interested in parting with it - or close by to North Potomac, do let me know!
I want to do this. Can you give a brief explanation of how you did it? I'm mainly curious about the resistors and what you used as a power source.
The little Varmilo board actually came with a little SMD resistor so I pretty much just soldered a USB cable to use a 5V power source such as a generic phone charger or your computers USB.
The resistor on the board is 189 ohms and the LEDs are 2V so on a 5V power source you'd have 3V leftover and with 189 ohm resistor it ends up being ~16 mA which works out fine for the LEDs I have. My computers USB has a 500 mA limit so even if I held down all 9 it would only be ~150 mA of draw. Now, I wouldn't hold down all of them because I'm pretty sure power dissipation would become an issue, but I think 4 at a time would be below a 1/4 watt.
To be safe you could put an extra ~150 ohm resistor between the LED and it would bring the current down to ~10 mA, but I think that would be overkill for something like this.
If anyone more knowledgeable wants to correct any of that please do. This is just something I did for fun based on my understanding.
Yes, I see it now. The resistor is so small I never caught it. I have some LEDs with a 20mA peak current so I should be all set. Thanks, Alex. I will post the results!
Yeah it didn't turn out so well. I had a few pins that just wouldn't take solder. Then when I soldered the negative leg to my USB cable the entire pad came off the PCB. I don't see any way to repair it. So that's that. Oh well, it was worth a shot. Still works as a switch tester. :P
Hahah yea I had the same issue with the solder not taking. For some reason the holes on the board aren't metal so it just won't attract solder. Don't remember how I got around it.
For the pad...you could try making a new pad out of solder?
Yeah, I might tinker with it. I'm also exploring having a new custom PCB made for it. That's how much the solder joints frustrated me. :P
Definitely let me know how that goes.