Question about illuminated buttons

I just received my first RioCar and ofcourse I can't leave it alone... I have to mod it with illuminated buttons...

I plan to use red leds, therefore I have a couple of questions. Since the white leds normally have Vf of about 3.5V and with 1kOhm resistor that should equal If of about 1.5mA. I guess I should be quite safe using a 2k2 resistorpack and low-current leds and not blow up the PIC? I could probably use 1kOhm as well since most PICs can sink 25mA...
The transistor for the knob is a PNP, isn't it?

And yes, I am able to solder the resistorpack...

Stig

If the supply voltage is 5V, subtract your LEDs Vf from that and then divide with wanted current to find the resistance. As long as you stay below or equal to the current Brians kits are drawing you should be OK. If your Vf is about 2V you should get about the same current if you use 2k or 2k2 resistors.

Have you considered using white LEDs and small pieces of filter material? That'd leave more options open for you in the future.

I believe, considering where the tranny is in the circuit, that it is a PNP - but I'm not 100% sure.

/Michael

StigOE, you do know about this project don't you?

Ofcourse! Where do you think I found out how to put this together...?

And now I have red buttons... Well, grey buttons with a hole, like Brians first(?) mod of his buttons. Haven't got around to make the board for the knob yet, though...

Stig

Haven't got around to make the board for the knob yet, though...

Currently my knob lights are sans-board. I wired them carefully in a linear fashion at the correct distance from each other, then threaded the assembly into a piece of clear shrink-tubing. That tube now encircles the encoder shaft.

I saw you mentioned that in a previous thread. Do you happen to have a picture how it looks? I can't seem to visualize how you did it...

Stig

Yes, right here.