28128 Parallax Inc, 28128 Datasheet - Page 27

• 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

Chapter 1: Analog Voltage and Binary States · Page 17
Why did I learn it?
In this experiment, we compared a binary LED output to an analog LED output. Aside
from knowing that the voltage at the wiper terminal had just crossed the threshold
voltage, there was no way of indicating the potentiometer's position or the LEDs
brightness. On the other hand, in the neighborhood of the threshold voltage, fine
variations in analog voltage could be detected.
Even with the limited amount of analog information provided by a binary input, we were
able to develop a device called a comparator, which has many applications in electronics
design. As we'll discover in a later experiment, the 555 timer in you’re A & D parts kit
can do some pretty amazing things. This is due in part to two microscopic comparators in
the chip.
How can I apply this?
In later experiments, we'll use the threshold voltage to measure the frequency of sound
for record and playback purposes. We can also build another type of analog to digital
converter using a very simple circuit, the BASIC Stamp and the concept of threshold
voltage. We'll use this technique to measure light intensity as well as values for
capacitors from the Analog and Digital parts kit.