70009 Parallax Inc, 70009 Datasheet - Page 113

• Manufacturer Part Number: 70009
• Description: BOOK UNDERSTANDING SIGNALS
• Manufacturer: Parallax Inc
• Type: Signal Analysisr

Specifications of 70009

• Style: Book
• Title: Understanding Signals
• Contents: Guide to Generate, View and Measure Wave Forms
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Other names: 70009PAR

depending on the op-amp used. With this configuration, you cannot attenuate the signal
like you could with the inverting amplifier; it can only be used to amplify. Let’s look at
the formula to calculate gain for this configuration:
Using a 1 kΩ resistor for both Rf and Ri would give a gain of 2. These formulas should
be good for a close approximation, but some “fine tuning” may be necessary depending
on what op-amp you use.
ACTIVITY #1: SINE WAVE THROUGH A NON-INVERTING AMPLIFIER
USING AN LM358 OP-AMP
In this activity, you will use a non-inverting op-amp circuit to amplify a sine wave that is
generated by the BASIC Stamp using the
different values for Ri and Rf to see how the gain determines how much to amplify the
signal. You will also examine signal clipping, which occurs when the circuit tries to
amplify the signal beyond the LM358’s dynamic range.
Parts Required
(2) 1 kΩ resistors
(1) 2 kΩ resistor
(1) LM358 op-amp
(1) 1µF Capacitor
(1) 220 Ω resistor
(9) Jumper wires
Building and Understanding the Non-Inverting Amplifier Circuit
The schematic (Figure 8-8) and wiring diagram (Figure 8-9) for this circuit are shown
below. As mentioned earlier, the resistors labeled Ri and Rf in the circuit are the input
and feedback resistors. The gain of the amplifier depends on the ratio of the values
selected for each of these resistors.
Gain
√
√
=
Set aside a 2 kΩ resistor to use in place of Ri and a 1 kΩ resistor to use in place
of Rf.
Build the non-inverting amplifier circuit shown in Figure 8-8 and Figure 8-9,
making sure to use a 2 kΩ resistor for Ri and a 1 kΩ resistor for Rf.
1
+
Rf/Ri
FREQOUT
command. You will be trying several