28119 Parallax Inc, 28119 Datasheet - Page 121

• Manufacturer Part Number: 28119
• Description: KIT UNDERSTANDING SIGNALS
• Manufacturer: Parallax Inc

Specifications of 28119

• Lead Free Status: Contains lead
• Accessory Type: Oscilloscope
• Interface Type: USB
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

In order to view this signal without a negative supply rail voltage, we can add DC voltage
to move the entire output waveform above 0 V so it will no longer be clipped.
process is called DC offset. This is accomplished with the 10 kΩ potentiometer
connected to the non-inverting input. This means that the op-amp circuit adds a DC
voltage to whatever signal is supplied to the circuit’s inverting input. By twisting the
potentiometer’s knob, the output signal will move into the viewable voltage range.
Parts Required
(1) 20 kΩ resistor
(1) 220 Ω resistor
(1) 10 kΩ resistor
(1) 1.0 µF capacitor
(1) 10 kΩ potentiometer
(1) LM358 op-amp
(9) Jumper Wires
Building the Variable Resistor Op-Amp Circuit
√
Build the circuit shown in Figure 8-14 and Figure 8-15. If you are using the
HomeWork Board, omit the 220 Ω resistor and make the necessary connection
with a jumper wire.
Negative voltages can be viewed by applying a negative 9 V to Vee with a separate power
supply. This is most easily done with a second 9 V battery. Disconnect the op-amp’s Vee
from the Vss on your Board of Education or HomeWork Board. Connect the battery’s
positive terminal to Vss on your Board of Education or HomeWork Board. Then, connect the
battery’s negative terminal to Vee.
WARNING: The 1.0 µF capacitor can explode if it is connected improperly!
Always disconnect the power before building or modifying circuits. Carefully check the
polarity of the 1.0 µF capacitor. The positive terminal (longer leg) must be connected to a
power source pin and the negative terminal (shorter leg) must be connected to Vss (ground).
This