# Current to Voltage Converter

Thread Starter

#### syee10

Joined Mar 26, 2010
59
Hi,

i want to design a simple current to voltage converter. Is there any basic idea and components that can help me to construct a I to V converter? Please assist me..

#### jpanhalt

Joined Jan 18, 2008
8,344
Try a resistor.

John

#### BillB3857

Joined Feb 28, 2009
2,506
Data, data! We need DATA! ......... Exactly what do you want to do? What is the starting situation and what is the desired result? How much current? What output voltage is required? What is the current source? etc, etc.

#### SgtWookie

Joined Jul 17, 2007
22,210
Voltage = Current x Resistance, or E=IR
If 10mA (0.01 Ampere) flows through a 1 Ohm resistor, you will measure 10mV across the resistor.
If 10mA flows through a 1,000 Ohm resistor, you will read 10v across the resistor.
If 10mA flows through an 0.1 Ohm resistor, you will read 1mV across the resistor.

Thread Starter

#### syee10

Joined Mar 26, 2010
59
I need to convert an input current (perhaps a range from microAmp to milliAmp) to a voltage in the range of 0-10V maximum. But at the same time the amount of input current must be proportional to my output voltage. For eg. 1mA = 1V output (this is only example). So can i just use an opamp like LM741 to make a current to voltage converter? If yes, how should be the circuit looks like?

#### BillB3857

Joined Feb 28, 2009
2,506
Again, data is needed. What are you going to use the voltage for? DVM,, etc. The end use of the voltage makes a BIG difference. Your thought of an OP-Amp would provide buffering, and possible range change by providing amplification. Sgt. Wookie's table would get you started. What level of understanding do you have of Ohm's Law?

#### SgtWookie

Joined Jul 17, 2007
22,210
See the attached; one way to do it.

U1/R1 make up a classic inverting transimpedance amplifier. V(out) = I(in) * -R1
In this case, I used 2k for R1, so 1mA in = 0.001 * -2000 = -2v out.

U2/R2/R3 make up an amplifier with a gain of -1; so with -2v in, 2v will be on the output.

Input offset is not accounted for here. You will need to trim offset adjustment to get the output correct. See the LM741 datasheet for details.

The 741 is a very old, slow opamp with linearity problems. This circuit will be OK for something that doesn't require a great deal of accuracy.

Supply bypass capacitors are not shown, but are required. See the datasheet.

See this Wikipedia entry:
http://en.wikipedia.org/wiki/Current-to-voltage_converter

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