28128 Parallax Inc, 28128 Datasheet - Page 136

• 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

Applying many narrow pulses as opposed to the single very wide pulse applied in Figure
7-3 has advantages in terms of accuracy. As you will soon find out, this D/A conversion
technique is surprisingly accurate - especially compared to the accuracy of the parts used
to make the conversion. The resistor has a 10% tolerance and the capacitor is only
accurate to 20%!
Parts Required
This experiment requires the following parts:
(1) ADC0831 A/D converter
(1) LM358 op-amp
(2) 10 k resistor
(1) 1.0 µF electrolytic capacitor
(1) Photoresistor
(1) 470
(1) Yellow LED
Voltage
Voltage
Output
(Volts)
(Volts)
Input
resistor
5
4
3
2
1
0
-0.02
5
4
3
2
1
0
-0.02
-0.01
-0.01
0
0
0.01
0.01
0.02
0.02
0.03
0.03
Time, (Seconds)
0.04
0.04
0.05
0.05
Figure 7-3
RC circuit Step
Response
Shows the
voltage response
to a single
voltage step
applied at the
input.