28128 Parallax Inc, 28128 Datasheet - Page 142

• 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

As you can see, a buffer is essential to keep the voltage steady. You can use the same
voltage follower that we used in Chapters #2, #4 and #5 to buffer the output.
Place a voltage follower in between the D/A output and the LED circuit input as shown in
Figure 7-8, then run Program Listing 7.1 again.
Figure 7-7
Debug Terminal
Output for Program
Listing 7.1 with an
Unbuffered 10 k
load.