I need a bit of help on a circuit im trying to build. I will try to explain my problem below.
Circuit requirements:*input to op-amp = 0 to 5v *output from op-amp = 0.5v to 3.5v
Im am currently using a CA3140E opamp with a 0.5v offset in it, which is quoted in the data sheet.
Pin wirring on chip:
Pin 1: to left leg of 10k pot pin 2: connected to pin 6 with no series resistor pin 3: varible input voltage, 0 to 5v pin 4: to middle leg of above 10k pot and connected to GND pin 5: to right leg of above 10k pot pin 6: connected to pin 2 with no series resistor, and then this voltage is dropped across 2 resistors in series to produce the output voltage ratio
Im at the stage in the circuit, that when you increase the input voltage from o to 5v, the output is alway 0.5v higher than the input which is correct. At this point i drop the output voltage over a potential divider and i get the correct output voltage ratio over this. The problem starts when a 1k load resistor is taken from the potential divider. At this point the voltage drops. When the load resistor is removed the circuit produces the correct output voltage again.
I think the problem is the circuit cant provide enough corrent, but i cant see how to change this.