1.) If transistors switched at 0.7v,then in order to control it with arduino i just need to write to the base leg\pin HIGH value? or is too much 5v for the base to handle?
npn like 2n2222
Yes. Arduino pin high to resistor 1000 ohms to base of npn transistor. Emitter grounded. Collector to load.
5v is not too much across the 1000 ohm resistor to base. Base is at about 0.8v.
Resistor has about 5.0 - 0.8 = 4.2 volts
2.) What is the difference between NPN and PNP?
npn has emitter grounded
pnp has emitter at 5 volts
npn base at 0mA for off
npn base at 1mA for on
pnp base at -0mA for off
pnp base at -1mA for on
npn collector has voltage above emitter
pnp collector has voltage below emitter
read the links
searched Youtube and looked at some videos-couldn't find adequate explanation and the one on Wiki is a little bit complicated for a begginer like me
the one thing i do understand is the one of them is 'switched on'(=connecting the collector and emitter like a switch) when the voltage on the base is high and the second one is switched on when the voltage on the base is low