SU399801A1 - DIGITAL METER - Google Patents

Description

one

The invention relates to a measurement technique and can be used in measuring x-classifiers of transistors for current transfer ratio.

Known digital meter, which contains measuring resistors included in the circuit of the base and emitter of the test transistor. This device automatically measures the current gain of the transistor PO in accordance with the relation:

B fie + 1

where gb is the current base of the test transistor; ha is the emitter current of the test transistor, and h iK + k,

where / k is the collector current of the test transistor, PO is the gain of the transistor

by ro b current

However, the lime meter does not directly measure the gain of ro and oi and has a greater measurement accuracy due to the inclusion of the measuring resistor in the base circuit, since the circuits shunting the emitter section — the base of the tested transistor — violate its mode io constant current and painfully

reduce the degree of short circuit at the output of the test transistor; measurement occurs in short circuit mode.

The aim of the invention is to improve the measurement accuracy and provide a direct measurement of the current gain of the transistor under test.

For this, the collector current meters and

the emitter of the test transistor is made in the form of transformers, the primary windings of which are included in the emitter and collector circuits of the test transistor, and the secondary windings through an electronic key

and the amplifier is connected to the relationship meter.

The drawing shows a block diagram of the pitch.

Digital meter - contains sources

1.2 power supply, sound generator 3, transformer 4, first 5, second 6 and third 7 about transformer 4 coils, measuring transformer cS, first 9 and second 10 windings of transformer 8, electronic K.poch

11, amplifier 12, a digital integrated ratio meter 13, coupling capacitors 14, 15; lemmas for connecting an electric 16, collects 17 and a base 18 of the test transistor 19, respectively.

The meter works as follows. Through the power supply sources 1, 2 connected to the emitter and collector circuits of the test transistor 19, a mode is established in which the current of the POS gain is measured by the SjViHTTepa circuit of the transistor 19 through the separation capacitor 14 and the winding 5 of the measuring transformer 4 supplies a low frequency signal from the sound generator 3. Secondary The winding 6 of the measuring transformer 4 is connected in series with the winding 9 of the measuring transformer 8, through a coupling capacitor 15 connected ene 17 to the collector of the test transistor 19. The voltage across the coil 5 a current proportional to the emitter of the transistor 19 of the test, and the voltage across the windings 6, 9 and 10 proportional to the current collector. Counter-switching of the windings 5 and 6 allows to obtain a voltage on the winding 7 of the measuring transformer 4 proportional to the base current of the test transistor 19, since 1b 1e-IK. The voltage from the windings 7 and 10 of the measuring transformers 4 and 8 is fed to an electronic switch 11, which commits these voltages, then amplified by an amplifier 12 and fed to a digital integrating meter 13 of the relationship, directly measuring the value of ro in accordance with the known relation: and fe IJk Р «- г- - where UK is the voltage proportional to the collector current of the tested transistor, t / b is the voltage proportional to the current of the base of the tested transistor. In addition, the digital integrating ratio meter 13 allows monitoring the measurement mode, which is necessary for setting the modes of the tested transistors of various types. A digital voltmeter with a push-pull time-pulse conversion containing an integrating amplifier is used as a digital integrating meter. If the integrating amplifier is first supplied with a voltage UK, then t / b vs; positive polarity, then after integrating these voltages we get (Jk ii iJe t, where ti is the voltage integration time, / X is the voltage integration time. In a digital voltmeter, the time t is fixed - this is the time of complete filling of the counting decades. Therefore, ro is tx, i.e., measuring the transistor current gain is reduced to determining the voltage integration time. Thus, the use of the proposed device allowed Improve the accuracy of direct automatic measurement of the transistor current gain factor Subject of the Invention A digital transistor gain factor meter comprising a power source, an amplifier, a sound generator, an electronic key and a collector and emitter current meter of the test transistor, characterized in that measuring and directly measuring the current gain of the transistor under test, measuring the collector and emitter currents and The transistor under test is made in the form of transformers, the primary windings of which are included in the emitter and collector circuits of the tested transistor, and the secondary windings are connected via an electronic switch and amplifier to a ratio meter.