XO10A低頻信號發生器

1.FEATURES

   Reliable circuitry insure high stability and accuracy

   Easy operation on vertical type panel assembling

   Frequency range from 10Hz to 1MHz selectable in 5 ranges are       calibrated with single-scale graduations.

   More than 5Vrms at no load and more than 2.8Vrms on 600Ω loading (sine wave). Output level can be adjusted by a 10dB-step, 6 range attenuator and a level adjuster.

   Sine wave and square waves is available.

   Synchronizing input terminal

2.Specifications

   Frequency range:

   X1 range:   10Hz-100Hz

   X10 range:  100Hz-1KHz

   X100range:  1KHz-10KHz

   X1K range:  10KHZ-100KHz

   X10K range:  100KHz-1MHz

   Sine wave characteristics

   Output volXO10A: 5V rms or more

   Output distortion: 400Hz-20KHz, 0.1% or less

                   (X100 range for 1KHz)

                  50Hz-500KHz 0.5% or less

   Output Flatness: ±1.5 dB (refer to 1KHz)

   Square wave characteristics:

   Output volXO10A: 10Vp.p or more

   Rise time: 0.25 us or less

   Duty  ratio: 50%±5%  (refer to 1KHz)

   External synchronization characteristics

   Range±3% of oscillator frequency

          Input impedance: 10K approximate

   Maxi mun input: 10V rms

   Output characteristics:

   Impedance: 600Ω±10%

   Attenuator: 0dB, -10dB, -20dB, -30dB, -40dB, and -50dB in 6 steps (accuracy +1 dB at 600Ω load)

   Power requirement:

   Input: AC 110V or 220V, 50/60Hz

   Consumption: 5 Watt

   Dimension:

   142(w)*233(D)*197(H) mm

   Weight:3.5Kg

   Accessories:

   Power cord           1pc

   Test clip              1pc

   Instruction manual       1pc

1.CIRCUIT DESCRIPTION

1) Summary

   When reading the following descriptions, refer to the block diagram(Fig.1) and the schematic diagram.

   The sine-wave signal generated by the oscillator is fed through the WAVE FROM selector switch set at the “ ” position to the OUTPUT control, to adjust on any desired volXO10A.

   If the WAVE FORM switch is in the “” position, square wave is fed to the OUTPUT control to adjust on any desired volXO10A.

   The adjusted signal volXO10A is applied to the output circuit with its impedance converted, and then delivered through an output attenuator to the output terminal.

   The attenuator provides selectable attenuations of 0dB through

          -50dB in 10dB steps at 600Ω of output impedance.

1) Wien Bridge Oscillator Circuit

   The Wien bridge oscillator circuit with resistance elements may be switched over for 5 ranges by the FREQ. RANGE switch, and the variable capacitor controlled by the FREQUENCY dial.

   These elements provide means to vary the oscillating frequency continuously over 10 times its frequency on one range, so any desired frequency within the entire frequency range from 10Hz to 1MHz can be set.

   The buffer circuit for the oscillator circuit is composed of a 2 sXO10A differential amplifier and an output sXO10A, employing an DC amplifier circuit.

   The output volXO10A is fed back with positive polarity through the oscillator elements to form an oscillating circuit; while it is also fed back with negative polarity through the non-linear thermistor to stabilize the amplitude.

XO10A低頻信號發生器

2) Square wave shaping circuit

   The square wave shaping circuit is a Schmit-trigger circuit in which the sine wave signal from the oscillator circuit is shaped into a square wave. Schmit-trigger circuit and a buffer amplifier providing sufficient rising and falling characteristics

3) Output circuit

   The output circuit converts the impedance of oscillating signal from the OUTPUT control and feeds the signal to the output attenuator at a low impedance. SEPP-OCL circuit is employed to provide sufficient low output impedance characteristics over the range from DC to 1MHz

4) Output Attenuator

   The 6-positions output attenuator selects attenuations of 0dB to -50dB in 10dB steps. At the 0dB position with the OUTPUT control

turned fully clockwise, the output volXO10A (sine wave at no-load time) is more than 5Vrms.

   The output impedance is rated at around 600Ω and the attenuation accuracy is as high as ± 1.0dB at 600Ω load.

1) Power supply

   The power supply circuit is powered by AC 110V/220V and delivers DC ± 24V sufficiently stabilized by large capacity smoothing capacitors and a volXO10A stabilizer.

4. PANEL CONTROLS AND THEIR FUNCTIONS

   The table below describes the functions of panel controls. Refer to panel diagram on page 4

   FRONT PANEL

   1. DIAL POINTER

   This pointer indicates frequencies on the dial scale

   2.DIAL SCALE

   This dial is calibrated with graduations of 10-100 to indicate oscillating frequencies

3. FREQUENCY DIAL

   This dial adjusts oscillating frequencies. Frequencies can be read by multiplying the reading on the dial scale by magnification of FREQ. RANGE.

   4. ATTENUATOR

   6-position output attenuator selects attenuations of 0dB to -50dB in 10dB steps.

   5. SYNC

   External synchronizing signal input terminals for GND for connection of synchronizing signal to the instruments.

   6. OUTPUT

   Output terminal used for both sine wave and square wave

   7. FREQ. RANGE

   Oscillating frequency range selector switch which selects the ranges in 5 steps as follows:

   X1       10Hz-100Hz

   X10      100Hz-1KHz

   X100     1KHz-10KHz

   X1K     10KHz-100KHz

   X10K    100KHz-1MHz

   8. WAVE FORM

   Output waveform selector switch. When pressed to “’ output signal is sine wave. When pressed to “” the signal is square wave.

   9. AMPLITUDE

   Amplitude adjuster to continuously vary the amplitude of output volXO10A

   10. POWER  Switch turns on the power when pressed

   11.VOLXO10A SELECTOR  110V/220V selection

   12. AC INPUT TERMINAL

   13. FUSE SOCKET

           14. This lamp ( light emitting diode) lights when POWER switch (10) is ON.

5. OPERATING INSTRUCIONS

  1) Start-up

    First check that the fuse (13), then connect the supplied AC  power cord to your AC outlet. Press the power switch (10) and the pilot lamp (14) will light indicating that the unit is ready for operation. Allow 3 minutes for the unit to warm up so that it is stabilized.

  2)Waveform selection

    Press the WAVE FORM switch (8) to “~” position to obtain sine waves. Press the switch to the “” position for square waves.

  3)Frequency selection

   First set the FREQ. RANGE switch (7) to the desired range, then set the frequency dial(3) so that the dial pointer(1) indicates your frequency.

Example: suppose you want to select a frequency of 1.5KHz, thenproceed as follows:

1. Set FREQ. RANGE switch(7) to X 100.

2. by using the frequency dial, set the dial pointer(1) to “15” on the dial scale.

The frequency thus selected is:

15×00=1500(Hz)=1.5( KHz)

   4) Adjustment of output volXO10A

   The output volXO10A from OUTPUT terminal (6) either sine wave or square wave, can be continuously varied by AMPLITUDE(9) and stepped down by ATTENUATOR (4)

Example: To adjust output volXO10A to 10mV rms, proceed as follows:

1. Connect a voltmeter (e.g. TVT-321) capable of measuring AC  1V rms to OUTPUT terminal (6)

2. Set ATTENUATOR (4) to 0dB and then adjust AMPLITUDE (9) until the voltmeter indicates 1Vrms (6)

3. Set ATTENUATOR (4) to -40dB. The voltmeter indicates about OV, while a volXO10A of 10mVrms appears at OUTPUT terminal (6)

5) USE of Synchronizing input terminal (instrument is between 990Hz and 1010Hz)

   By applying an external sine wave signal to SYNC terminal (5), the oscillating frequency can be synchronized to the external signal. Synchronizing range is increased in proportion as the input volXO10A is increased as shown in Fig.3, indicating that the synchronizing range is about 1% per input volXO10A of 1V.

Example: Suppose that the input signal volXO10A is 1Vrms and the 

oscillating frequency of GENERATOR is between 990Hz and 1010Hz(1KHz±1KHz×1%/v×1V=1KHz±1KHz×0.01), the frequency can be synchronized with 1KHz of the input signal.

   Note that too high synchronizing signal volXO10A will affect the amplitude and distortion factor, and care must therefore be taken when the signal volXO10A is higher than 3Vrms. Also, note that if the synchronizing signal is largely deviated the distortion factor. It is therefore advisable that the oscillating frequency be first synchronized with a low input signal volXO10A (less than 1Vrms) and then the volXO10A be increased.

6. APPLICATIONS

1) Using as sine wave oscillator

   As a sine wave oscillator, features can be noted as below.

1.1 Low distortion factor can be obtained for measurement of distortion characteristic of amplifier.

1.2 As the unit working on wide bandwidth, it can be used for measurement of frequency characteristic of amplifier.

1.3 The built-in high accuracy attenuator permits measurement of amplifier gain.

1.4 Can be used as a signal source of impedance bridge.

2)Measurement of amplifier gain

   An example of measurement of amplifier gain is described below

   First connect the instrument, amplifier to be tested and AC 

volt-meter as shown in Fig.4

2.1Adjust ATTENUATOR (4) and AMPLITUDE(9) so that AC voltmeter indicates the rated output (supposed to be 1 Vin this example) of the amplifier. To facilitate the measurement, it is advisable to set ATTENUATOR(4) as low as possible. Assume that ATTENUATOR (4) is set -50dB for the rated output.

2.2 Disconnect the amplifier and connect the AC voltmeter to instrument to measure the output volXO10A. Note that the use of ATTENUATOR (4) eliminates the need for connecting a high sensitivity voltmeter. If ATTENUATOR(4) is set to 0dB and the voltmeter indicates 2V, it means that the input volXO10A of the amplifier is 50dB below 2V. Therefore, the gain obtained is as follows:

3) Measurements of phase characteristic

   Connect the instrument and an oscilloscope to the amplifier to be tested as shown in Fig5. If there is no phase shift about the output signal of the amplifier, the oscilloscope will display a straight line as shown in Fig. 5A. If the straight line on the oscilloscope is curved at its top and bottom sections as shown in Fig.5B, it indicates that the output signal of amplifier is suffering from an amplitude distortion. In this case, reduce the output level of instrument a little to vary the 

frequency. This causes the straight line on the oscilloscope to expand gradually to turn into an ellipse. By utilizing the configuration of this ellipse. The phase shift can be calculated as follows:

   First, measure the maximum horizontal deflection and suppose that this deflection is”X” and that the section at which the ellipse crosses the horizontal axis is “X, as show in Fig.6. And, the phase shift angle θ is given by the following

Find from the table of trigonometric functions and the value obtained gives the angle of phase shift.

4)  Using as square wave oscillator

    The instrument features excellent rising and falling characteristics (120ns as standard characteristic.) it has no coupling capacitors in the output sXO10A, so the sag (deflection of top section) is as low as 5% at 50Hz. By applying such a good square wave to an amplifier input, various characteristics of amplifier can be observed on an oscilloscope. To test an amplifier proceed as follows:

4.1 connect the instrument, an amplifier to be tested and an oscilloscope as shown in Fig7.

4.2 Press WAVE FORM (8) to the “” position to obtain square waves of appropriate frequency and amplitude.

4.3 During the test, change the frequency as necessary. The relationship between waveforms and amplifier characteristics is shown in Fig.8