PE01 UJT Characteristics Operating Manual Ver.1 UJT Characteristics Operating.pdf · PE01 UJT...

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PE01 UJT Characteristics Operating Manual Ver.1.1 An ISO 9001 : 2000 company 94-101, Electronic Complex Pardesipura, Indore- 452010, India Tel : 91-731- 2570301/02, 4211100 Fax: 91- 731- 2555643 e mail : [email protected] Website : www.scientech.bz Toll free : 1800-103-5050

Transcript of PE01 UJT Characteristics Operating Manual Ver.1 UJT Characteristics Operating.pdf · PE01 UJT...

Page 1: PE01 UJT Characteristics Operating Manual Ver.1 UJT Characteristics Operating.pdf · PE01 UJT Characteristics Operating Manual Ver.1.1 An ISO 9001 : 2000 company 94-101, Electronic

PE01 UJT Characteristics

Operating Manual Ver.1.1

An ISO 9001 : 2000 company

94-101, Electronic Complex Pardesipura, Indore- 452010, India Tel : 91-731- 2570301/02, 4211100 Fax: 91- 731- 2555643 e mail : [email protected] Website : www.scientech.bz Toll free : 1800-103-5050

Page 2: PE01 UJT Characteristics Operating Manual Ver.1 UJT Characteristics Operating.pdf · PE01 UJT Characteristics Operating Manual Ver.1.1 An ISO 9001 : 2000 company 94-101, Electronic

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RoHS Compliance

Scientech Products are RoHS Complied. RoHS Directive concerns with the restrictive use of Hazardous substances (Pb, Cd, Cr, Hg, Br compounds) in electric and electronic equipments. Scientech products are “Lead Free” and “Environment Friendly”. It is mandatory that service engineers use lead free solder wire and use the soldering irons upto (25 W) that reach a temperature of 450°C at the tip as the melting temperature of the unleaded solder is higher than the leaded solder.

PE01 UJT Characteristics

Table of Contents

1. Introduction 4

2. Theory 6

3. Experiments Experiment 8 Study of the characteristic of Unijunction Transistor (UJT) and to calculate interbase resistance and intrinsic standoff ratio

4. Data Sheet 11

5. Warranty 12 6. List of Accessories 12

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Introduction PE01 is a compact, ready to use UJT Characteristics experiment board. This is useful for students to plot characteristics & various region of operation of UJT. It can be used as stand alone unit with external DC power supply.

List of Boards : Model Name PE02 MOSFET Characteristics PE03 SCR Characteristics

PE04 TRIAC Characteristics PE05 DIAC Characteristics PE06 IGBT Characteristics` PE07 PUT Characteristics PE10 SCR Triggering (R, RC Full wave, RC Half wave) PE11 SCR Triggering (UJT) PE12 SCR Triggering (IC555) PE13 SCR Triggering (IC74121) PE14 Ramp and Pedestal triggering PE15 SCR Triggering (IC741) PE16 SCR Triggering (PUT) PE40 SCR Lamp Flasher

PE41 SCR Alarm Circuit PE42 Series Inverter

PE43 UJT Relaxation oscillator PE44 Signal Phase PWM Inverter

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List of other Boards available are : Model Name ST2701 IGBT Characteristics ST2702 SCR Triggering (R, RC Half wave, RC Full wave) ST2703 SCR Triggering Techniques

ST2704 Triggering of SCR using 74121 IC ST2705 SCR Lamp Flasher ST2706 SCR Alarm Circuit ST2707 Series Inverter ST2708 Single Phase Controlled Rectifier

(With Ramp Comparator Firing Scheme) ST2709 Single Phase Controlled Rectifier with Cosine

Firing Scheme ST2710 Single Phase Converter Firing Techniques

ST2711 Lamp Dimmer ST2712 Power Electronics Lab

ST2713 Single Phase Cycloconverter

ST2714 Speed Control of Universal Motor Using SCR

ST2715 Speed Control of AC Motor Using TRIAC

ST2716 Micro Controller Based Firing Circuit for Controlled Rectifier

ST2717 SCR Commutation Circuits

ST2718 Bedford and Parallel Inverter

and many more…

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Theory The uni-junction transistor (UJT) is a three terminal device Emitter (E), basel (BI) and base2 (B2). Between basel & base2 it behaves like an ordinary resistance. Rb1 & Rb2 are internal resistance respectively from base 1 & base2.

UJT characteristics are very different from the conventional 2 junction, bipolar transistor. It is a pulse generator with the trigger or control signal applied at the emitter. This trigger voltage is a fraction (n) of interbase voltage, Vbb. The UJT circuit symbol and basic construction is shown in figure 1. Its characteristic curve is shown in figure 2.

Figure 1

It operates in three different regions : 1. Cut-off region

Let voltage Ve be applied between E and B 1 where E is positive with respect to B1. Now increase this voltage from zero upto (Ve < ηVBB) E to B1 unijunction is reversed bias & emitter current is negative as shown by the curve in figure 2.

So upto this when Ve =VBB + VD at point R in figure 1 it operates in cut off region, corresponding voltage & current at this point are Vp (peak voltage) & Ip (peak current).

2. -VE resistance region

At point R in figure 1 when Ve= ηVBB + VD emitter starts to inject holes into lower base region B1. This is because of increased number of carrier in base region. So, resistance Rb1 of E-B1 junction decreases.

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Figure 2

Due to this potential at A in figure 2 decrease & current Ie due to voltage Ve increases, so this region is negative resistance region shown by point RS in figure 2.

It is a stable region. Decrease in resistance is due to the holes injected into the n-type slab to p-type when conduction is established.

3. Saturation region At point S in figure 2 entire base region is saturated & resistance Rb1 does not

decrease any more. This region is called as saturation region. Further increase in Ie is accompanied by voltage Ve where point is called valley point. Voltage and current at this point is called valley voltage (Vv) & valley current (Iv).

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Experiment Objective : Study of the characteristic of Unijunction Transistor (UJT) and to calculate inter base resistance and intrinsic standoff ratio Equipments Needed : 1. Power Electronics Board PE01.

2. DC power supplies + 15 V. 3. Digital multi-meter.

4. 2mm patch multimeter.

Circuit diagram : Circuit used to plot different characteristics of unijunction transistor is shown in figure 3

Figure 3

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Procedure :

• Connect + 15V DC power supply at their indicated position from external source.

1. To plot the emitter characteristics proceed as follows: 2. Rotate both the potentiometer P1 and P2 fully in counter clockwise direction.

3. Connect one voltmeter between test point ‘6’ and ground to read VBB and other between test point ‘1’ and ground to read Ve.

4. Connect ammeter between point ‘2’ and ‘3’ to measure the emitter current Ie and at point ‘4’ and ‘5’ to measure the base current lb.

5. Switch ‘On’ the power supply. 6. Vary potentiometer P2 and set a value of voltage VBB = 5 V.

7. Increase the emitter voltage Ve in steps. 8. Keep increasing Ve until it drops on voltmeter, UJT fires and emitter current

flows rapidly. 9. Record the corresponding Emitter current for each value of Emitter voltage Ve

in an observation table 1. 10. Repeat the above procedure from step 8 for VBB = 10 V and 15 V.

11. Plot the graph of Ve versus Ie with the help of observation table 1.

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Observation Table :

Emitter current IE at constant value of output voltage

Serial Number Emitter Voltage

V VBB = 5V VBB = 10V VBB = 5V

1

2

3

4

5

6

7

8

9

10

11

12

13

14

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Calculations : 1. Interbase Resistance(Rss)

It is the sum of resistance between base 1 & base2. RBB = RB1 + RB2

It ranges from 4 to 10 KΩ when Ie = 0.

2. Intrinsic Stand-off Ratio (η)

η = RB1 (RB1 + RB2) = RBB1 RBB It ranges from 0.51 to 0.82.

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Data Sheet

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Warranty 1. We guarantee the product against all manufacturing defects for 24 months from

the date of sale by us or through our dealers. Consumables like dry cell etc. are not covered under warranty.

2. The guarantee will become void, if

a) The product is not operated as per the instruction given in the operating manual.

b) The agreed payment terms and other conditions of sale are not followed.

c) The customer resells the instrument to another party. d) Any attempt is made to service and modify the instrument.

3. The non-working of the product is to be communicated to us immediately giving full details of the complaints and defects noticed specifically mentioning the type, serial number of the product and date of purchase etc.

4. The repair work will be carried out, provided the product is dispatched securely packed and insured. The transportation charges shall be borne by the customer.

For any Technical Problem Please Contact us at [email protected]

List of Accessories

1. 2 mm Patch Cords (Red) ........................................................................1 No. 2. 2 mm Patch Cord (Black) .......................................................................1 No. 3. 2 mm Patch Cord (Blue) .........................................................................1 No. 4. e-Manual.................................................................................................1 No.

Updated 21-02-2009