I gave my son my old 28-278 in preparation for an electronics class. However, it needs the red and green LED(s) what voltage should I get? I'm pretty sure I cannibalized them making some guitar pedals for myself, and can't remember if they were 12v 5v or lower. The kit uses a 9v battery I think but I could be wrong. I thought I inventoried everything before I sent it off to him and wouldn't you know it, the first experiment needed one and there wasn't one. I went through all 98 + experiments, recording the IC's , transistors capacitors and resistors etc, and missed the LED's. Any help would be greatly appreciated.