Use the same RadioShack stock resistors in Example 7.6 to design the construction of a voltage divider that will reduce the voltage by a factor of 30.

Example 7.6

Suppose you want to build a voltage divider that will reduce the voltage by a factor of 15. You visit your local Radio- Shack store and find that they have 5.0, 10., 15., and 20. ohm resistors in stock. Which ones do you choose to make your voltage divider in the simplest and most economical way?

Need: An inexpensive voltage divider such that V_out /V_in = 1/15. = 0.067.

Know: The voltage divider Equation (7.4), and a supply of resistors.

How: Since we know that V_out /V_in = R₂ / (R₁ + R₂) = 0.067, we could just try the values of the resistors in stock to see if we can get close to the required ratio. This is a trial-and-error method and in the general case well suited to a spreadsheet analysis.