liinstaller
New Member
I attached a circuit borrowed from WinPicProg tutorials. Hope they don't mind for an educational purpose.
I understand the basics of how the circuit works but would like to know how to calculate resistor values. I understand how to calculate the values for a single transistor acting as a switch from a PIC but once you throw in a second as in the attachment I become lost. It's not for any particular design so lets just assume that it requires 100mA from T2 and each transistor has a current gain of 50. Also La2 doesn't have to be a lamp.
I understand the basics of how the circuit works but would like to know how to calculate resistor values. I understand how to calculate the values for a single transistor acting as a switch from a PIC but once you throw in a second as in the attachment I become lost. It's not for any particular design so lets just assume that it requires 100mA from T2 and each transistor has a current gain of 50. Also La2 doesn't have to be a lamp.