# Differential Voltage generation

Discussion in 'The Projects Forum' started by skeptor, Feb 5, 2013.

1. ### skeptor Thread Starter New Member

Feb 5, 2013
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0
Hello guys, A quick question..... how do i generate a differential voltage??, i need it as an input to the INA128.

i understand this can be done using supply voltage and the use of a pot resistor..... a broader explanation would be appreciated

2. ### #12 Expert

Nov 30, 2010
18,082
9,646
It's considered helpful to post the datasheet for your chip. But really, your question is a bit vague. Sometimes the only reason it's called "differential" is the way you arrange the circuit. Please ramble on a bit so we can get a grip on exactly what you need.

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3. ### crutschow Expert

Mar 14, 2008
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Do you need this for a test of the INA128?

4. ### skeptor Thread Starter New Member

Feb 5, 2013
15
0
crutschow: exactly!!! i need a differential voltage input to test the INA128..... and figure out a suitable gain value for my circuit. BTW i'm building an ECG ckt. anyways, my main concern is to try and experiment with different gain value and see how much noise interference is included at each different gain value and then, by using an integrator as a feedback would like to set a DC offset voltage in order to compensate for the high frequency DC components.

@#12 : guess this helps u understand better!!

5. ### Papabravo Expert

Feb 24, 2006
11,735
2,483
Start with an adjustable current source and connect it to a resistor. The differential inputs will be on either side of the resistor. For example if the resistor is 1K Ohms and the current source puts out 500 μA, the voltage across the resistor will be: 0.5Volts. You can scale the current source and the resistor to any convenient range.

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6. ### crutschow Expert

Mar 14, 2008
20,216
5,715
What supply voltages are you using to power the INA128?

7. ### skeptor Thread Starter New Member

Feb 5, 2013
15
0
Thank you guys i got the solution for it !!! appreciate your help

I used a pot on one i/p terminal of the amp and then just supplied both the terminals with one voltage......by varying the resistance i was able to generate two different voltages one for each and obtained a differential input.