The Differential Voltage Probe is designed for exploring the basic principles of electricity. Use this probe to measure currents in low voltage AC and DC circuits. With a range ±6.0 V, this system is ideal for use in “battery and bulb” circuits. Use it with the Current Probe to explore Ohm’s law, phase relationships in reactive components and much more. This differs from the Voltage Probe that comes with your interface in that neither clip is connected to ground. Use multiple sensors to explore series and parallel circuits. This sensor has the same characteristics as the Voltage Probe from the Vernier Current and Voltage Probe System.
Using the Voltage Probe with a Computer¶
Connect the Differential Voltage Probe to any of the analog ports on LabPro (in most cases, Channel 1 is used)
Start the Logger Pro® software on the computer.
You are now ready to collect data. Logger Pro will identify the Differential Voltage Probe and load a calibration. Click on Collect and begin collecting data.
Specifications¶
Differential Voltage Probe input voltage range: ± 6.0V Max. voltage on any input: ±10 V Input Impedance (to ground): 10 M∧ Linearity: 0.01% Resolution (using LabPro): 3.1 mV Supply voltage: 5 VDC Supply current (typical): 9 mA Output voltage range: 0 - 5 V Transfer function : Vo = 0.4 (V+ V-) + 2.5
How the Differential Voltage Probe Works¶
The Differential Voltage Probe measures the potential difference between the V+clip (red) and the V- clip (black). The voltage probes have differential inputs. The voltage measured is with respect to the black clip and not circuit ground. This allows you to measure directly across circuit elements without the constraints of common grounding. The voltage probes can be used to measure negative potentials, as well as positive potentials. This is a nice improvement for people using one of our 0 to 5 volt interfaces. The voltage probes are designed to be used like voltmeter leads. They should be placed across a circuit element. The differential input range is 6 volts to +6 volts. Over-voltage protection is provided so that slightly higher voltages will not damage the sensor. You should NEVER use high voltages or household AC with these probes.
Do I Need to Calibrate the Differential Voltage Probe? “No”¶
You should not have to perform a new calibration when using the Differential Voltage Probe in the classroom. We have set the sensor to match our stored calibration before shipping it. You can simply use the appropriate calibration file that is stored in your data-collection program from Vernier in any of these ways: 1. If you are using the Differential Voltage Probe with a LabPro, then a calibration is automatically loaded when the Differential Voltage Probe is detected. 2. If you manually load an experiment or calibration file, choose the Current & Voltage Probe system. The calibration for the Differential Voltage Probe is the same as for the Voltage Probe in this older system.
The output of this system is linear with respect to the measurement it is making. As mentioned before, the amplifier allows you to measure positive and negative voltages on any of our interfaces. Since many lab interfaces can read voltages only in the range of 0 to 5 volts, the amplifier offsets and amplifies the incoming signal so that the output is always in the range of 0 to 5 volts. If an input is zero volts, for example, the amplifier will produce an output of 2.5 volts. The output varies from this 2.5 volt level, depending on the input. To collect data as differential current, use either the calibration supplied with your program, or calibrate the unit using known voltages. A standard, two-point calibration is done, as with any Vernier sensor. Another option to consider instead of calibrating is “zeroing” the sensor. This is done by
shorting out the leads of the sensor, then choosing the Zero option in the data-collection software. This option adjusts the calibration offset but does not adjust the calibration gain.
The default calibration slopes and intercepts for these sensors are: Potential in volts: Slope: −2.5 V/V Intercept: 6.25 V