Hi, I am working to create a circuit In which I can control a light using my computer's parallel port; however, I am having trouble getting my transistor to work properly.
Circuit Diagram:
I have preformed the following tests with my voltage meter. Note that the junctions described are notated on the circuit in green text. For reference, the parallel port provides an output of 6.2v when set to high, and 0.11 when set to low.
I need to expand this range of voltages to the relay coil in both directions. The voltage needs to be higher to trip the relay, and needs to be less (the coil remains tripped at 5v) to deactivate it.
How can I expand the range of this transistor. I thought initially that it might have to do with my resistor. If so, what value resistor should I use?
Thanks for your help.
Circuit Diagram:
I have preformed the following tests with my voltage meter. Note that the junctions described are notated on the circuit in green text. For reference, the parallel port provides an output of 6.2v when set to high, and 0.11 when set to low.
- Port On; Point 4 (6.2v); Point 2 (12v); Point 1 (7.93v)
- Port Off; Point 4 (0.11v); Point 2 (12v); Point 1 (4.92v)
I need to expand this range of voltages to the relay coil in both directions. The voltage needs to be higher to trip the relay, and needs to be less (the coil remains tripped at 5v) to deactivate it.
How can I expand the range of this transistor. I thought initially that it might have to do with my resistor. If so, what value resistor should I use?
Thanks for your help.