How do I calculate the base resistor value?
I saw a formula:
Rb = (V(ic supply) x hFE) / (5 x I(load))
and also I saw
Ic/Ib = hFE
and I heard:
Ib should be a tenth of Ic but if the gain is 100 than it should be a hundredth?
I'm very confused.
I have attached the schematic.
My output to the transistor base is a quad AND gate IC which will operate a 24VDC relay.
I saw a formula:
Rb = (V(ic supply) x hFE) / (5 x I(load))
and also I saw
Ic/Ib = hFE
and I heard:
Ib should be a tenth of Ic but if the gain is 100 than it should be a hundredth?
I'm very confused.
I have attached the schematic.
My output to the transistor base is a quad AND gate IC which will operate a 24VDC relay.
Attachments
-
55.9 KB Views: 77