simple power supply LED indicator :)

Just a little LED to know if the power supply is powered or not:



Connecting wires directly to the power supply entry:



120 ohms (x4) connected to the 3v led:



Same mod on a MD2:

 

Why not have 1 single 510 ohm resistor instead of the 4 in series?

 

He may have a bunch of 120 ohms resistor to use up. But a single 500-ish is enough for most LED on 5v rail without being too bright. (blue and white LED would need higher resistor value simply because they are stupidly bright at times)

 

I tried with a single 480 Ohms resistor and it fried ^^; (had only 0.25W resistors) It could have worked with a single 0.5W or 2 x 0.25W resistors, but just to be safe and with 4 resistors, I'm sure they wont even warm

 

Assuming you're limiting LED volt to 1.5v 20mA, you are dumping 0.07w of power into resistor. Your .25w resistor should have been enough. Either the resistor you had before was a dud or something else happened like maybe accidental short?

 

Looking at the picture above he's taking in 9-10v to the resistors which is likely why they fried, you might want to tap into the 5v regulator instead since it only receives power when the wall wart is plugged in and less voltage going to the resistors.

 

I think it fried cause my (official sega) power supply is outputting +-14,5V despite 10V announced on the box. So, (14.5V-2.5V)/.025A gave me 480Ohms, and +- 0.3W which was a little bit too much for a single resistor. I should have tried .02A or even .015A in first place. Maybe for the next console ^^; But I prefer safety first, and certainly will end with 2 or 3 resistors in series anyway.

 

I'm not sure to understand. The goal of the mod is to indicate when the power supply is plugged and powered by electricity. So, 10V to 15V seems the only choice here. (theres no 5V available while the console is not running)

 

You're correct, I don't know what I was thinking lol.