I've never used a 741 and decided to play with one today. Wired it up as a comparator like the circuits shown here:
http://www.circuitstoday.com/voltage-comparator
I am using 5 volts as my supply voltage and instead of the two fixed resistors as a voltage divider I am using a 100K pot to vary the voltage. I used a fixed voltage divider to give my reference voltage of 2.5 volts. The output (pin 6) goes through a 330 ohm resistor to an Led.
My issue is that even though it does go high and low on the output, in the low state I am still getting 1.9 volts (4.8 volts at high). I tried a 10K pulldown resistor from pin 6 to ground but that didn't help. The Led still glows even in the low state.
My intention was to use an NPN transistor on pin 6 but I don't think it would ever turn off with the 1.9 volts on the base.
Any ideas?
http://www.circuitstoday.com/voltage-comparator
I am using 5 volts as my supply voltage and instead of the two fixed resistors as a voltage divider I am using a 100K pot to vary the voltage. I used a fixed voltage divider to give my reference voltage of 2.5 volts. The output (pin 6) goes through a 330 ohm resistor to an Led.
My issue is that even though it does go high and low on the output, in the low state I am still getting 1.9 volts (4.8 volts at high). I tried a 10K pulldown resistor from pin 6 to ground but that didn't help. The Led still glows even in the low state.
My intention was to use an NPN transistor on pin 6 but I don't think it would ever turn off with the 1.9 volts on the base.
Any ideas?