Unijunction transistor voltage division ratio test circuit

Abstract

The utility model relates to a voltage division ratio test circuit for a unijunction transistor, which belongs to the field of electronic device parameter test and is characterized in that a test terminal b2 of the unijunction transistor to be tested is connected with a positive electrode of a direct-current power supply E; a test terminal b1 of the unijunction transistor to be tested is connected with the negative electrode of the direct-current power supply E; a test terminal e of the unijunction transistor to be tested is respectively connected with one end of the second resistor R2, one end of the second capacitor C2 and the anode of the diode VD, and the cathode of the diode VD is connected with one end of the button SB, one end of the first capacitor C1 and one end of the adjustable resistor RP1; the other end of the second resistor R2 is connected with the positive electrode of the power supply and the other end of the button SB; the other end of the first capacitor C1 is connected with the other end of the second capacitor C2 and the negative electrode of the direct-current power supply E; and the other end of the microammeter is connected with the other end of the first capacitor, the other end of the second capacitor and the negative electrode of the direct-current power supply E. The test circuit has the advantages of simple structure, accurate and visual measurement and the like.

Description

Technical Field

[0001] The utility model relates to the field of electronic device parameter testing, in particular to a single junction transistor voltage division ratio testing circuit. Background Art

[0002] The unijunction transistor, also known as the double base diode, is a semiconductor device with only one PN junction inside and three lead terminals connected to the outside. It has a strip substrate inside, which is a high-resistance N-type silicon wafer. Two base electrodes b1 and b2 are respectively led out by ohmic contacts at both ends of the substrate. A P region is made by alloy method in the middle of the silicon wafer, slightly to the side of b2, as the emitter e.

[0003] Unijunction transistors have negative resistance characteristics and are widely used in electronic devices and integrated circuits. They are mainly used in thyristor trigger circuits, sawtooth wave generators, step wave generators and other circuits.

[0004] The voltage division ratio is an important parameter of the unijunction transistor, which determines whether the unijunction transistor can operate in the negative resistance region and whether it can play its important negative resistance role.

[0005] The voltage divider ratio of a unijunction transistor is:

[0006]

[0007] where r b1 and r b2 They are the equivalent resistances of the first base and the second base in the unijunction transistor respectively.

[0008] If a circuit fails, the cause of the failure can be determined by comparing the peak voltage determined by the voltage divider ratio of the single junction transistor with the voltage at other locations.

[0009] When using a unijunction transistor currently, it is often necessary to look up the parameter table based on the marked model to determine the voltage divider ratio of the unijunction transistor. Summary of the invention

[0010] In view of the problems existing in the prior art, the utility model provides a single junction transistor voltage divider ratio test circuit to solve the problem raised in the above background technology that it is inconvenient to find information and determine the single junction transistor voltage divider ratio.

[0011] To achieve the above purpose, the utility model is implemented by the following technical scheme: a single junction transistor voltage divider ratio test circuit, characterized in that it includes a DC power supply E, a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a diode VD, an adjustable resistor RP1, a button SB and a microammeter;

[0012] The test terminal b2 of the unijunction transistor under test is connected to the positive electrode of the DC power supply E;

[0013] The test terminal b1 of the unijunction transistor under test is connected to the negative electrode of the DC power supply E;

[0014] The test terminal e of the tested unijunction transistor is respectively connected to one end of the second resistor R2, one end of the second capacitor C2, and the anode of the diode VD.

[0015] The cathode of the diode VD is connected to one end of the button SB, one end of the first capacitor C1, and one end of the adjustable resistor RP1;

[0016] The other end of the second resistor R2 is connected to the positive electrode of the power supply and the other end of the button SB;

[0017] The other end of the first capacitor C1 is connected to the other end of the second capacitor C2 and the negative electrode of the DC power supply E;

[0018] The other end of the adjustable resistor RP1 is connected to one end of the first resistor R1;

[0019] The other end of the first resistor R1 is connected to one end of the microammeter;

[0020] The other end of the microammeter is connected to the other end of the first capacitor, the other end of the second capacitor and the negative electrode of the DC power supply E;

[0021] Furthermore, the first resistor R1 is 50 kΩ, the second resistor R2 is 10 kΩ, the potentiometer is 50 kΩ, the first capacitor C1 is 1 uF, and the second capacitor C2 is 0.1 uF.

[0022] The advantages of the utility model are obvious, mainly manifested in:

[0023] 1. By using the utility model, the voltage division ratio value of the single junction transistor can be quickly measured, and it is convenient to select the single junction transistor element according to the value of the DC power supply E or to select the appropriate power supply according to the voltage division ratio of the single junction transistor element.

[0024] 2. By using the utility model, the peak voltage value of the single junction transistor can be quickly obtained and compared with the voltage of other places in the circuit (the trigger circuit of the thyristor, the sawtooth wave generator, the step wave generator and other circuits), so as to facilitate the search for circuit faults.

[0025] The utility model has the advantages of simple structure, convenient adjustment, and can quickly select single junction transistors and quickly judge circuit faults (faults of other electronic circuits composed of single junction transistors).

[0026] The test circuit has the advantages of simple structure, accurate and intuitive measurement, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 This is a circuit diagram of the utility model. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The specific implementation example of the utility model is shown in the attached figure. Figure 1 shown.

[0032] A single junction transistor voltage divider ratio test circuit, comprising: the circuit consists of a DC power supply E, a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a diode VD, an adjustable resistor (potentiometer) RP1, a button SB and a microammeter; the first resistor R1 is 50kΩ, the second resistor R2 is 10kΩ, the potentiometer is 50kΩ, the first capacitor C1 is 1uF, and the second capacitor C2 is 0.1uF;

[0033] The test terminal b2 of the unijunction transistor under test is connected to the positive electrode of the DC power supply E;

[0034] The test terminal b1 of the unijunction transistor under test is connected to the negative electrode of the DC power supply E;

[0035] The test terminal e of the tested unijunction transistor is respectively connected to one end of the second resistor R2, one end of the second capacitor C2, and the anode of the diode VD.

[0036] The cathode of the diode VD is connected to one end of the button SB, one end of the first capacitor C1, and one end of the adjustable resistor RP1; the other end of the second resistor R2 is connected to the positive electrode of the power supply and the other end of the button SB;

[0037] The other end of the first capacitor C1 is connected to the other end of the second capacitor C2 and the negative electrode of the DC power supply E;

[0038] The other end of the adjustable resistor RP1 is connected to one end of the first resistor R1;

[0039] The other end of the first resistor R1 is connected to one end of the microammeter;

[0040] The other end of the microammeter is connected to the other end of the first capacitor, the other end of the second capacitor and the negative electrode of the DC power supply E.

[0041] The working principle of the utility model is: the single junction transistor to be tested, the resistor R2 and the capacitor C2 form an oscillating circuit.

[0042] After the power is turned on, the DC power source E charges the second capacitor C2 through the second resistor R2. When the voltage across the second capacitor C2 reaches the peak voltage of the unijunction transistor, the unijunction transistor is turned on, and the second capacitor C2 is quickly discharged through the unijunction transistor. As the second capacitor C2 is charged and discharged, an approximate sawtooth voltage is obtained at both ends of the second capacitor C2, i.e., at the emitter e end of the unijunction transistor. The voltage formula of the emitter e end is as follows:

[0043]

[0044] Where: Ue is the emitter voltage of the unijunction transistor, r b1 and r b2 is the first base resistance and the second base resistance of the single junction transistor, U D is the conduction voltage drop of the equivalent diode inside the unijunction transistor.

[0045] The diode VD, the first capacitor C1, the potentiometer RP1, and the microammeter form a sawtooth wave peak measurement circuit. After the power is turned on, the Ue sawtooth wave voltage charges the first capacitor C1 through the diode VD. Since it charges quickly and discharges slowly (it can only discharge through the potentiometer RP1 and the microammeter), after several oscillation cycles, U' A The peak voltage of the sawtooth wave is U P The difference with the forward voltage of diode VD is U′ A =U P -U D =U A (Potential at point A inside the tube being tested).

[0046] During measurement, when the button SB is not turned on, the current reading flowing through the microammeter is A1, then:

[0047] U e =A1(R RP +50kΩ)+U D

[0048] When the button SB is pressed, the current flowing through the microammeter is A2, then:

[0049]

[0050] Substituting into the above formula, we get:

[0051] U e =A1E / A2+U D

[0052] The emitter voltage formula of a single junction transistor is:

[0053]

[0054] Compared to:

[0055]

[0056] The ratio of the two readings of the microammeter is the voltage divider ratio of the unijunction transistor.

[0057] The above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. All technicians familiar with the technical field shall be covered by the protection scope of the present invention by making equivalent replacements or changes based on the technical scheme of the present invention and the concept of the present invention within the technical scope disclosed by the present invention.

Claims

1. A single junction transistor voltage divider ratio test circuit, characterized in that: It includes a DC power supply E, a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a diode VD, an adjustable resistor RP1, a button SB and a microammeter; The test terminal b2 of the unijunction transistor under test is connected to the positive electrode of the DC power supply E; The test terminal b1 of the unijunction transistor under test is connected to the negative electrode of the DC power supply E; The test terminal e of the tested unijunction transistor is respectively connected to one end of the second resistor R2, one end of the second capacitor C2, and the anode of the diode VD. The cathode of the diode VD is connected to one end of the button SB, one end of the first capacitor C1, and one end of the adjustable resistor RP1; The other end of the second resistor R2 is connected to the positive electrode of the power supply and the other end of the button SB; The other end of the first capacitor C1 is connected to the other end of the second capacitor C2 and the negative electrode of the DC power supply E; The other end of the adjustable resistor RP1 is connected to one end of the first resistor R1; The other end of the first resistor R1 is connected to one end of the microammeter; The other end of the microammeter is connected to the other end of the first capacitor, the other end of the second capacitor and the negative electrode of the DC power supply E.

2. A single junction transistor voltage divider ratio test circuit according to claim 1, characterized in that: The first resistor R1 is 50 kΩ, the second resistor R2 is 10 kΩ, the potentiometer is 50 kΩ, the first capacitor C1 is 1 uF, and the second capacitor C2 is 0.1 uF.

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