MikeyH_0001
- Apr 21, 2012
- 5
- Joined
- Apr 21, 2012
- Messages
- 5
Hello,
I have been trying out a voltage comparator circuit using a few LM1458 (dual op-amp) ICs. I am a little confused by the behaviour I have been getting in my circuit.
I have a 5v input to the V+ pin and the V- pin is grounded. The output runs through a 100ohm resistor and then is grounded.
I have two parallel lines from the 5v supply, one with two 100ohm reistors (1), and the other with a 100ohm followed by a switch followed by a 10kohm resistor (2) where both are grounded.
The inverting input is connected between the two resistors on line 1, and the non-inverting input is connected between the switch and a 10kohm reistor on line 2.
My understanding is that this circuit should output 5v (ideal) from the op-amp when the switch is closed and 0v while open.
What I actually see is 1.4V while closed and 1V while open. This is from an actual power supply of 4.1V (from a 5V regulator w/ 6V battery source).
Can anyone see any issue with my circuits that would cause this behaviour, or is my understanding of the behaviour of an op-amp off here?
I'm not sure how tolerant these ICs are to static, but I have been handling them with a grounding strap on. However, I cannot say the same for the staff of the store where I brought them. They handled the chips and then put them straight into a plastic carrier bag (I don't mean an anti-static bag). Being the amatuer, I assumed they knew what they were doing.
Any help would be greatly appreciated here.
- Mike
I have been trying out a voltage comparator circuit using a few LM1458 (dual op-amp) ICs. I am a little confused by the behaviour I have been getting in my circuit.
I have a 5v input to the V+ pin and the V- pin is grounded. The output runs through a 100ohm resistor and then is grounded.
I have two parallel lines from the 5v supply, one with two 100ohm reistors (1), and the other with a 100ohm followed by a switch followed by a 10kohm resistor (2) where both are grounded.
The inverting input is connected between the two resistors on line 1, and the non-inverting input is connected between the switch and a 10kohm reistor on line 2.
My understanding is that this circuit should output 5v (ideal) from the op-amp when the switch is closed and 0v while open.
What I actually see is 1.4V while closed and 1V while open. This is from an actual power supply of 4.1V (from a 5V regulator w/ 6V battery source).
Can anyone see any issue with my circuits that would cause this behaviour, or is my understanding of the behaviour of an op-amp off here?
I'm not sure how tolerant these ICs are to static, but I have been handling them with a grounding strap on. However, I cannot say the same for the staff of the store where I brought them. They handled the chips and then put them straight into a plastic carrier bag (I don't mean an anti-static bag). Being the amatuer, I assumed they knew what they were doing.
Any help would be greatly appreciated here.
- Mike