Op-Amp IC Circuit Tester
In the diagram above I am using an IC No. LM339 Op-Amp for my demonstration… You can use any op-amp for the tester just the input and output pins will be different.
· The supply is a 12Volts DC and supplies Pin 3 (Vcc) positive and Pin 12 (Gnd) negative.
· R1 and R2 are 10k which is a Voltage divider, between them would give you 6 volts to pin6 (input 2 Negative).
· R5 is a 10k Pot that goes to pin 7 (Input 2 Positive) and to ground.
· R3 is also a 10k resistor from the positive of the supply to pin 1 (Output 2).
· R4 is from Pin 1 to an LED.
You can connect the same for all inputs and outputs of the IC to Test.
Principle of operation
With a supply of 12 Volts DC to Pin 3 and which also passes through R1 and R2 to ground, between R1 & R2 you will get 6 Volts in reference to Ground that is going to pin6 (Input 2 Negative) which is a Constant voltage. However, on Pin 7 of LM339 a 10 K pot is supplying Voltage to the positive of input 2 and this can be varied from 0 to 12 volts DC using the POT. Theory is that if Pin 6 is 6 volts and by varying the 10K POT on Pin 7 to get above 6 Volts you will get an output on Pin 1 and the LED will be Lit, if the voltage on Pin 7 is lower that Pin 6 Volts Out 2 will be Zero. This Test can be done on all the inputs and outputs for the Op-Amp.
I built this tester on a Bread board with removable wires so I can adjust the inputs and outputs and power supply and you can test any op-amps that is 14, 16 pins etc. You really can’t make it a permanent fix because you will be changing around the wires for different op-amps. Different op-amps have different pins for power, input and outputs. Those who understand how the op-amp works will be able to easily test variety of Op amp ics. See the below picture of the circuit using a LM224N Chip.
This article was prepared for you by Andre Gopee from Calitech Limited Trinidad West Indies.
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