I need to switch a logic signal between 9 and 0 volts using a 5v signal and 9v supply. I am driving a Lego motor that takes a constant 9v and uses two 9v logic pins to tell it which way to go.
http://www.philohome.com/pf/pf.htm
The problem is that it seems to have no tolerance for variation in voltage. At 9.05v it wont spin with a logic signal resistance of anything more than 300ohms. I discovered this when I tried to use my multimeter to see how much current the 9v logic signal used. The multimeter read about 40mA but the motor did not spin. It will only spin with a direct 9v connection to one logic pin and 0 on the other in addition to the 9v power and gnd.
My idea WAS to use a transistor to switch the 9v logic signal and a pulldown to ground to make it 0v when the transistor is off but I don't think it will tolerate a voltage drop for the 9v or any resistance on the 0v. How can I switch these signals?
Thanks.
http://www.philohome.com/pf/pf.htm
The problem is that it seems to have no tolerance for variation in voltage. At 9.05v it wont spin with a logic signal resistance of anything more than 300ohms. I discovered this when I tried to use my multimeter to see how much current the 9v logic signal used. The multimeter read about 40mA but the motor did not spin. It will only spin with a direct 9v connection to one logic pin and 0 on the other in addition to the 9v power and gnd.
My idea WAS to use a transistor to switch the 9v logic signal and a pulldown to ground to make it 0v when the transistor is off but I don't think it will tolerate a voltage drop for the 9v or any resistance on the 0v. How can I switch these signals?
Thanks.