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Scale a 5V Signal to 3.3V


This How-to is intended for: Any audience.

Convert a 5V signal (common with many sensors) to 3.3V (required by the Make Controller).

Problem

You have a sensor, or some other input device that puts out a signal from 0-5V, and you'd like to use that with the Make Controller (which accepts inputs from 0-3.3V). 

 

Solution

With a simple circuit and a couple of very cheap components, you can scale the signal from your sensor to 3.3V.  The circuit is called a voltage divider, and requires just two resistors.  The circuit looks like this:

 

5to3divider.png

 

Discussion

R1 and R2 are resistors, and must maintain a ratio of 5 to 3.3 to arrive at the correct voltage. For the most precision, R1 should be 20K and R2 should be 39K. However, because these values are not so common for resistors, 10K and 15K will also work quite well.  You should be able to find these resistors at your local Radio Shack, or any other electronics store.