28128 Parallax Inc, 28128 Datasheet - Page 122

• Manufacturer Part Number: 28128
• Description: KIT BASIC ANALOG/DIGI PARTS ONLY
• Manufacturer: Parallax Inc

Specifications of 28128

• Accessory Type: ADC, DAC
• Product: Microcontroller Accessories
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Page 112 · Basic Analog and Digital
Now, try adjusting pot B and make the low signal two asterisks wide. What happened to
the pulse width? It should also have gotten narrower too.
Next, try adjusting pot B as far as it will go to increase the frequency (making the pulse
widths narrower). The piezoelectric speaker should be clicking pretty fast now. Carefully
adjust pot A and you should be able to hear an audible tone out of the piezo speaker. It's
not a pretty tone; it sounds about like a kazoo.
The Stamp-O-Scope 2 is probably not working very well any more, as shown in Figure 6-
6. We'll replace it with another program that lends itself to measuring audible sound.
Figure 6-6: Output Sample of Faster Pulse Train