Using Custom probes in PicoScope 7

The Custome Probes feature allows you to correct for gain, attenuation, offsets and nonlinearities in probes, sensors or transducers that you connect to the oscilloscope. A simple use would be to linearly scale the output of a current probe so that it correctly displays amperes. A more advanced use would be to scale the output of a nonlinear temperature sensor using the table lookup function.

Definitions for standard Pico-supplied oscilloscope probes and current clamps are included. User-created probes may be saved for later use.

For example applications click here.

How to Setup a Custom Probe

First open the Channel Options for the channel you'd like to add a custom probe to. Switch to the Probes tab, and select Add  to open the Custom Probe dialog.

In the Details page you can give the probe a name and a Unit - which can be picked from the selection or typed into the text box. 

To continue, click Next.

On the Scaling page you can either use an Equation or a Table to apply a scaling factor to the physical probe input. 

In the Equation method (left), you can add a gradient (m) and/or an offset (c) to your probe and use the example table below to verify the scaling with example voltage inputs. 

Alternatively use the Table method (right) to plot your own scale on specific points throughout a scaling function similar to the equation example table.

In the Options page you can adjust the standard channel options such as:

These are all adjustable in the channel settings after finishing the custom probe dialog.

Click Finish to save and enable your custom probe.

Your custom probe will now be available under the Custom section under the channel Probes tab. This new custom probe will now be avaliable for future use and can be saved into .PSDATA files.
To Edit or Delete the custom probe use the respective buttons under the Manage probes section. 

Example Custom Probe Applications

Comparison between a x1 probe (red), built-in x10 probe (green) and custom x10 probe (blue).

Custom x10 Probe

A simple example you can create is a x10 custom probe. Although the PicoScope software already has x10 built in, it's a quick example to get you familiar with the custom probe interface.

The setup for this is simple, in the custom probe dialog we've kept the probe settings as default, but we've set the equation to y=10x+0 V.

Table method example (1 V - 100%, -1 V - 0%)

Voltage to Percentage

In this example we're using a 800 mV AC waveform, and converting the voltage range to a percentage using the table method. For this we'll set 1 V as 100% and -1 V as 0%. 

In the screenshot to the right, we can see the peak values (800 mV and -800 mV) are about 90% and 10% of the total ±1 V scale we used. 

Table method example (1 V - 100%, 0 V - 25%, -1 V - 0%)

When creating a scale using the table method, it will create a linear scale between each row of the table. For example if we add a row stating 0 V is 25%, we should see a step in the waveform showing the two steps of the linear scaling.

Make sure to take this into account when using the table method, when looking for a smooth scale, switch to the equation method.