28119 Parallax Inc, 28119 Datasheet - Page 98

• Manufacturer Part Number: 28119
• Description: KIT UNDERSTANDING SIGNALS
• Manufacturer: Parallax Inc

Specifications of 28119

• Lead Free Status: Contains lead
• Accessory Type: Oscilloscope
• Interface Type: USB
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

In this example we are using the external trigger function of the OPTAscope 81M. This
keeps the waveform on the screen and prevents it from jumping around, which is also
called false triggering. You can see this by temporarily selecting the CH2 button as the
trigger source.
If you were trigging on the IR detector you’d miss the picture because it would require a
signal change (from high to low) to trigger.
Turning on the Autoscale button will display all 1,500 data points of the signal in the Plot
Area, as shown in Figure 7-9. Notice the Plot Area Indicator bar disappears. This gives the
added benefit of better resolution at a 1ms time base, and you can still see the entire pulse
train.
With the Autoscale button activated, the divisions or boxes on the screen no longer equal 1
ms per box. We have crunched the data so now each box is three times the selected time
√
Under the Cursors tab, turn on the Autoscale button.
Figure 7-9:
Using the
external
trigger feature