Hi im near the point of giving up of trying to learn electronics... My problem is that i cant switch a relay with my parallell port trough a transistor.
The design is basic and calculum too..and i wander whats wrong. Please tell me what am i doing wrong so i can get back on track :D
Transistor 2N2222a : Vbe = 0.7V Vce sat = 0.3V hfe = 10 Icmax = 500mA Vcemax=100V
Relay: Rr = 426ohm Vturn on= 12V
Parallell port: Vcc= 3.4V
I_bsat= 50e-3 / 10 = 5mA Rb = (Ve- VbeSat) / I_bsat = (3.40 - 0.3) / 5e-3 = 3.1 / 5e-3 = 620 ohm +12V | relay | c
+3.40V -----Rb----b 2n2222a | e | | ---- ----- -- -- Please if you think the answer is to obvious bother to reply