130-28176 Parallax Inc, 130-28176 Datasheet - Page 170

• Manufacturer Part Number: 130-28176
• Description: KIT PARTS PROCESS CONTROL
• Manufacturer: Parallax Inc

Specifications of 130-28176

• Accessory Type: Education Kit
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Board of Education Full Kit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Figure 5-14 shows the schematic symbol for an op-amp, though most times the supply
voltage connections are not shown. Figure 5-14 also shows the pins of the LM358 dual
op-amp.
Figure 5-15 is a buffer configuration. With V
must the output be to balance the inputs? With the output tied directly to the non-
inverting input, the output must be V
How can this be beneficial in our circuit? Since the inputs are of extremely high
impedance, the op-amp configuration can be used to buffer the filtered PWM voltage
before it is used to drive a device. The op-amp cannot be used to directly drive the fan
because it can only supply about 20 mA, but we'll worry about that later. First, let's test
an op-amp buffer circuit.
O
= 2 V to balance the inputs.
I
= 2 V on the non-inverting input, what
Figure 5-14
The LM358 Op-Amp
Schematic Symbol
(top) and Pin Map
(bottom)
Figure 5-15
Typical Op-Amp
Buffer Circuit