thanks for the help:
I though i would need another switching transistor to turn the NPN in the green ring on, at the same time that i turn the top right hand corner on ?
the 2n2222 npn will that be strong enough ? it says that the Vceo is only 30, now I'm using 48V so i think i wont lose 18 volts in my system so the voltage could blow this transistor ?
Look at the ZTX [651 or 653] series of medium power transistors.
also how can the Collector current of the 2n2222 be the same as the base current at R3, from the micro controller?
They are not the same, R11 with the BC109 emitter follower is 190R and R11 is 220R direct from the PIC..
the green ring
i thought i needed to switch on the darlington NPN in order to get hte system to work ?? like send a signal from themicro to pin one and pin 4 ?? is that wrong ?
The darlington only requires about 15mA, this will switch ON the darlington, the PIC can output 20mA.