Vernier Tech Info Library TIL #1972

Question

How do I measure voltages larger than 6 (or 10) volts?

Answer

First of all, we do not recommend ever having students work with voltages over about 20 volts in any situation where any significant current could be supplied. This can be dangerous and is not an appropriate use of our products. (Static electricity is the obvious case where students will work with high voltages.)

Our Differential Voltage Probe (DVP-BTA) has a range of -6 to +6 volts. Our simple voltage probe (VP-BTA) has a range of -10 to +10 volts. If you want to measure voltages somewhat higher than that, you can usually use the voltage divider concept. For example, if you want to measure voltages in the range of -20 to +20 volts with the VP-BTA sensor, you could connect two 1000-ohm resistors in series between the points where you want to make the voltage measurement and then connect the VP-BTA leads across one of the two resistors. The voltage probe will read half of the voltage and you can do a New Calculated Column so that the proper voltage is displayed in the software. Note that in this example we are using 2000 ohms of resistance across the voltage to be measured, so only a small current will be drawn. You can make the resistors somewhat higher resistance, to reduce this current even more.

Many solar panel projects require measurement of more than 10 volts and this concept is often useful for these projects.

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Created by: dvernier on April 01 2009
Last updated by: dvernier on April 01 2009