Bryan

I have a 5 volt input ( old cell phone charger), with 220 ohm resistor connected to 6 3mm leds (3 red 3blue) running in parallel. When connected, it did not burn out any of the leds, but only the blue leds light up and one red. How much smaller of a resistor do i need?

I'm getting a 3D printer soon, and have a windows 8.1 laptoo. Do i need a windows 8 pro or widows 8.1 pro laptop, or will mine work?

Okay! I do not get it! I'm building a diy turntable, and I'm trying to use a potentiometer to control the motor that spins the turntable. I've tried a 100k ohm pot, 10k ohm pot, and a 1k ohm pot. They seem to barely work. I have to turn them all the way up for them to work. And even then it doesnt control the speed, they just turn on. I don't know if theyre too big or not. I'm using an input of 5.1v .7a (cell phone charger) and a 5v motor that i got from radioshack. Also my other problem is that everytime the pots do make it turn on, they make a bright light and start smoking. Its burning them and i have no idea why. If the pots are too big for it then why is it burnin them? They shouldnt be hurt by the little power anyways? Please help! Thanks alot!

Do I need a transformer? And what size?

Do I need a transformer? And what size?

I took apart a cheap laser that i got from the store today to get the laser out. However, this laser doesnt look like a diode, just a flat piece of the board with two small metal contacts on each side. I'm wondering what this is called and where is the positive and negative sides?