Apparatus for measuring characteristics of electronic devices

Claim 1

An apparatus for measuring characteristics of electronic divices, comprising: generator means for synthesizing a symmetrical alternating voltage in phase with an AC line voltage, said generator means including a variable frequency signal generator, a frequency divider for producing a plurality of divided output signals by dividing an output frequency of said variable frequency signal generator, a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage and controlling an oscillation frequency of said variable frequency signal generator in response to the comparison result, converter means for converting an input signal into the alternating voltage in response to the divider output signals from said frequency divider, and a voltage comparator for comparing a voltage corresponding to the alternating voltage from said converter means with a reference voltage so as to generate the input signal to said converter means; voltage supply means for supplying said alternating voltage from said generator means to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; and display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means.

Claim 2

An apparatus for measuring characteristics of electronic divices, comprising: generator means for synthesizing a symmetrical alternating voltage in phase with an AC line voltage, said generator means including a variable frequency signal generator, a frequency divider for producing a plurality of divided output signals by dividing an output frequency of said variable frequency signal generator, a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage and controlling an oscillation frequency of said variable frequency signal generator in response to the comparison result, converter means for converting an input signal into the alternating voltage in response to the divider output signals from said frequency divider, and a voltage comparator for comparing a voltage corresponding to the alternating voltage from said converter means with a reference voltage so as to generate the input signal to said converter means; voltage supply means for supplying said alternating voltage from said generator means to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; and display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means.

Claim 5

An apparatus for measuring characteristics of electronic devices, comprising: generator means for synthesizing a symmetrical alternating voltage in phase with an AC line voltage; voltage supply means for supplying said alternating voltage from said generator means to an electronic device under test, said voltage supply means including a transformer having a primary winding to receive the alternating voltage from said generator means and a secondary winding with a plurality of taps, switch means for selecting one of the plurality of taps of said secondary winding, and a rectifier for rectifying an output signal from said switch means, an output signal from said rectifier being applied to said electronic device; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; and display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means.

Claim 6

An apparatus for measuring characteristics of electronic devices, comprising: generator means for synthesizing a symmetrical alternating voltage in phase with an AC line voltage; voltage supply means for supplying said alternating voltage from said generator means to an electronic device under test, said voltage supply means including a transformer having a primary winding to receive the alternating voltage from said generator means and a secondary winding with a plurality of taps, switch means for selecting one of the plurality of taps of said secondary winding, and a rectifier for rectifying an output signal from said switch means, an output signal from said rectifier being applied to said electronic device; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; and display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means.

Claim 7

An apparatus for measuring characteristics of electronic devices, comprising: generator means for synthesizing a symmetrical alternating voltage in phase with an AC line voltage; voltage supply means for supplying said alternating voltage from said generator means to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device, wherein said current detector means includes a current detecting resistor inserted into a current path of said electronic device under test, one terminal of said current detecting resistor being connected to one terminal of said electronic device, and a differential amplifier having two input terminals connected to respective terminals of said current detecting resistor for detecting a voltage across said current detecting resistor; and display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means.

Claim 8

An apparatus for measuring characteristics of electronic devices, comprising: generator means for synthesizing a symmetrical alternating voltage in phase with an AC line voltage; voltage supply means for supplying said alternating voltage from said generator means to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device, wherein said current detector means includes a current detecting resistor inserted into a current path of said electronic device under test, one terminal of said current detecting resistor being connected to one terminal of said electronic device, and a differential amplifier having two input terminals connected to respective terminals of said current detecting resistor for detecting a voltage across said current detecting resistor; and display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means.

Claim 10

An apparatus for measuring characteristics of electronic devices, comprising: generator means for synthesizing a symmetrical alternating voltage in phase with an AC line voltage; voltage supply means for supplying said alternating voltage from said generator means to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; and display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means; said apparatus including storage means for storing the output signals from said voltage detector means and said current detector means and applying the stored signals to said display means.

Claim 11

An apparatus for measuring characteristics of electronic devices, comprising: generator means for synthesizing a symmetrical alternating voltage in phase with an AC line voltage; voltage supply means for supplying said alternating voltage from said generator means to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; and display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means; said apparatus including storage means for storing the output signals from said voltage detector means and said current detector means and applying the stored signals to said display means.

Claim 17

An apparatus for measuring characteristics of electronic devices, comprising: voltage supply means for supplying a voltage to an electronic device under test; a current detecting resistor inserted into a current path of said electronic device under test, one terminal of said current detecting resistor being connected to one terminal of said electronic device; a differential amplifier having two input terminals connected to terminals of said current detecting resistor for detecting a voltage across said current detecting resistor; a voltage divider connected between one terminal of said current detecting resistor adjacent to said voltage supply means and the other terminal of said electronic device; a first buffer amplifier having an input terminal connected to an output terminal of said voltage divider; a second buffer amplifier having an input terminal connected to one terminal of said electronic device; a third buffer amplifier having an input terminal connected to one terminal of said current detecting resistor adjacent said voltage supply means; an operational circuit coupled to receive output signals from said first, second and third buffer amplifiers, an output signal from said operational circuit corresponding to the voltage across said electronic device; and display means for displaying a characteristic curve of said electronic device in accordance with output signals from said differential amplifier and said operational circuit.

Claim 18

An apparatus for measuring characteristics of electronic devices, comprising: voltage supply means for supplying a voltage to an electronic device under test; a current detecting resistor inserted into a current path of said electronic device under test, one terminal of said current detecting resistor being connected to one terminal of said electronic device; a differential amplifier having two input terminals connected to terminals of said current detecting resistor for detecting a voltage across said current detecting resistor; a voltage divider connected between one terminal of said current detecting resistor adjacent to said voltage supply means and the other terminal of said electronic device; a first buffer amplifier having an input terminal connected to an output terminal of said voltage divider; a second buffer amplifier having an input terminal connected to one terminal of said electronic device; a third buffer amplifier having an input terminal connected to one terminal of said current detecting resistor adjacent said voltage supply means; an operational circuit coupled to receive output signals from said first, second and third buffer amplifiers, an output signal from said operational circuit corresponding to the voltage across said electronic device; and display means for displaying a characteristic curve of said electronic device in accordance with output signals from said differential amplifier and said operational circuit.

Claim 19

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider, wherein said waveform generator generates a sine-wave voltage as the alternating voltage; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; and current detector means for detecting the current flowing through said electronic device.

Claim 20

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider, wherein said waveform generator generates a sine-wave voltage as the alternating voltage; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; and current detector means for detecting the current flowing through said electronic device.

Claim 22

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test, said voltage supply means including a transformer having a primary winding to receive the alternating voltage from said waveform generator and a secondary winding with a plurality of taps, switch means for selecting one of the plurality of taps of said secondary winding, and a rectifier for rectifying an output signal from said switch means, an output signal from said rectifier being applied to said electronic device; voltage detector means for detecting the voltage across said electronic device; and current detector means for detecting the current flowing through said electronic device.

Claim 23

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test, said voltage supply means including a transformer having a primary winding to receive the alternating voltage from said waveform generator and a secondary winding with a plurality of taps, switch means for selecting one of the plurality of taps of said secondary winding, and a rectifier for rectifying an output signal from said switch means, an output signal from said rectifier being applied to said electronic device; voltage detector means for detecting the voltage across said electronic device; and current detector means for detecting the current flowing through said electronic device.

Claim 24

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; and current detector means for detecting the current flowing through said electronic device, wherein said current detector means includes a current detecting resistor inserted into a current path of said electronic device under test, one terminal of said current detecting resistor being connected to one terminal of said electronic device, and a differential amplifier having two input terminals connected to respective terminals of said current detecting resistor for detecting a voltage across said current detecting resistor.

Claim 25

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; and current detector means for detecting the current flowing through said electronic device, wherein said current detector means includes a current detecting resistor inserted into a current path of said electronic device under test, one terminal of said current detecting resistor being connected to one terminal of said electronic device, and a differential amplifier having two input terminals connected to respective terminals of said current detecting resistor for detecting a voltage across said current detecting resistor.

Claim 26

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; analog-to-digital converter means for converting the output signals from said voltage detector means and said current detector means to digital signals in response to a clock pulse generated in synchronism with the alternating voltage; and a memory for storing input signals from said analog-to-digital converter means.

Claim 27

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; analog-to-digital converter means for converting the output signals from said voltage detector means and said current detector means to digital signals in response to a clock pulse generated in synchronism with the alternating voltage; and a memory for storing input signals from said analog-to-digital converter means.

Claim 28

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means; analog-to-digital converter means for converting the output signals from said voltage detector means and said current detector means to digital signals in response to a clock pulse generated in synchronism with the alternating voltage; a memory for storing output signals from said analog-to-digital converter means; and digital-to-analog converter means for converting the digital signals stored in said memory to analog signals to be applied to said display means.

Claim 29

An apparatus for measuring characteristics of electronic devices, comprising: a variable frequency signal generator for generating a signal having a frequency higher than that of an AC line voltage; a frequency divider for producing a plurality of divided output signals by dividing the output frequency of said variable frequency signal generator; a phase comparator for comparing one of the divided output signals from said frequency divider with the AC line voltage, an oscillation frequency of said variable frequency signal generator being controlled in response to the comparison result; a waveform generator for generating an alternating voltage in phase with the AC line voltage in response to the divided output signals from said frequency divider; voltage supply means for supplying the alternating voltage from said waveform generator to an electronic device under test; voltage detector means for detecting the voltage across said electronic device; current detector means for detecting the current flowing through said electronic device; display means for displaying the characteristic of said electronic device in accordance with output signals from said voltage detector means and said current detector means; analog-to-digital converter means for converting the output signals from said voltage detector means and said current detector means to digital signals in response to a clock pulse generated in synchronism with the alternating voltage; a memory for storing output signals from said analog-to-digital converter means; and digital-to-analog converter means for converting the digital signals stored in said memory to analog signals to be applied to said display means.