I have voltage measured in range 3.2V -4.2V. I need to convert this to range 0-10V using opamp circuit.Can anyone help me realise this.
input will be 3.2V to 4.2V Actually my original circuit is like i ve 32V to 42V which need be scaled to 0-10V. I used a differential opamp circuit to reduce the voltage to 3.2V-4.2V range.Now i need to change to 0-10V. I need to use opamp, and in the first stage i had to use differential opamp .so did like that. anythng wrong?or is ther an alternate way?
is ther any steps to arrive at these Resistor values?i mean design, so that i cud know the circuit more.
The voltage gain mus be equal : Au = (10V - 0V) / (4.2V - 3.2V) = 10V/1V = 10[V/V] So gain of a non-inverting amplifier is equal: Ku = 1 + (R1/R2) then R1/R2 = 9 so R1 = 9*R2 so i start with R2 = 20KΩ R1 = 9 * 20K = 180KΩ. And we wont for Vin = 3.2V Vout = 0V and this can only be done when non-invent input "+"V is equal inventing input voltage "-"V. So we have this situation: So voltage divider voltage must be larger then 3.2V by voltage drop on a R2. Vd = 3.2V + I * R2 I = 3.2V /180KΩ = 17.77uA then Vd = 3.2V + 17.77uA * 20KΩ = 3.2V + 0.355V = 3.555V So we must design voltage divider that deliver 3.555V Voltage on R3 = 15V - 3.555V = 14.445V 14.445V/ 3.555V = 3.2194 = R3/R4 R3 = 3.2194 * R4 = 470Ω * 3.2194 = 1.513K = 1.5K I start with low value for a R4 because current that is flow through R3 and R4 must be much large then current that is flow through R1, R2.