2
The Function Generator (order code FGEN-PAMP) comes with a BNC-mono
cable designed for use with the Power Amplifier.
Use the function generator’s controls to select the waveform and frequency you
wish to use in your experiment. When used with this input, the Power Amplifier
applies a factor of ten gain to the input signal. The input is DC-coupled.
Videos
View videos related to this product at
Specifications
LabQuest Audio (3.5 mm connector) Input
l
DC coupled between tip and sleeve of 3-conductor connector
l
Frequency range DC to 15 kHz.
l
Overall gain 10X
l
Input impedance 10 kΩ.
BTA Analog Input
l
DC coupled and has a total gain of 2X to the output.
l
Input impedance is 50 kΩ.
l
Maximum input ±12V without damage.
l
This input is on pin 1, or the yellow wire, of the BTA Cable (see
for details)
BTA Current Sensing
l
There is a 0.1 Ω resistor between the black terminal and ground. Current
measurements are based on the voltage drop across this resistor.
How the Sensor Works
The Vernier Power Amplifier is a DC-coupled amplifier capable of delivering 1 A
at 10 V. In many applications, the amplifier will simply increase the amplitude of
the input signal. This is true for audio-frequency applications.
In other applications a much lower frequency output is desired. Since many audio
sources are not DC-coupled, the Power Amplifier includes a novel pulse-width-
modulated (PWM) input to create extremely low-frequency waveforms and DC
offsets. The output of the PWM section is added to the input of the amplifier. For
example, an experiment might demand a signal of a few hertz. A typical signal
generator cannot create an output at that frequency, but the Power Amplifier can
generate such a waveform when driven with the correct PWM signal.
Finally, a current-sensing resistor allows monitoring of the output current. This
signal is available at the current-sense output connector. When this output is
connected to an analog input of a LabQuest or LabPro, a calibrated, autoID current
sensor is detected by software.
Input DC Blocking
Some signal sources contain an undesirable DC offset. Since the Power Amplifier
is DC-coupled in order to produce DC signals, any offset will be amplified
Use Power Amplifier with LabQuest App
Power Amplifier connected to a LabQuest audio out connector
The Power Amplifier requires a LabQuest 3, LabQuest 2, or original LabQuest
with LabQuest App 1.2 or newer. (LabQuest App 1.3 or newer is recommended.)
Launch the LabQuest Power Amplifier App by selecting it in the home menu. If it
is not present in the home menu, see www.vernier.com/labquest/updates/ for
information on updating your original LabQuest.
The Power Amplifier App includes waveform options of sine, triangle, square
wave, ramp up, and ramp down and DC. For the sine, square wave, ramp, and
triangle waveforms, you can set the frequency with the keyboard, the up and down
arrow keys, and the slider. The slider provides an easy way to change the
frequency: tap to the right or left of the slider control to double the current setting,
or drag the control to change the frequency smoothly. The VDC control is only
used for the DC waveform.
The Power Amplifier App can be run simultaneously with LabQuest App. For
example, the current sense output of the Power Amplifier is used with the
LabQuest App, while the control of the Power Amplifier is retained by the Power
Amplifier App. To switch between them, choose each by name in the LabQuest
home menu. This way you can control the output of the Power Amplifier while
simultaneously recording the current in LabQuest App.
Use Power Amplifier with Function Generator
The Vernier Power Amplifier can be used with most function generators. Connect
the function generator to the 3.5 mm input using a mono connector only. A stereo
connector may enable the PWM features of the Power Amplifier with undesirable
results. When used with this input, the Power Amplifier applies a factor of ten
gain to the input signal. The input is DC-coupled.
Connecting a function generator to the Power Amplifier with a mono audio cord
The Vernier Power Amplifier can be used with most function generators. Connect
the function generator to the 3.5 mm input using a mono audio connector only.
