transistor/diode tester model dt-100 - TechEdu.com

TWO YEAR WARRANTYAll Elenco models are guaranteed for two full yearson all parts and service. For the first 3 months,your power supply is covered at absolutely nocharge. For the remaining 21 months, a nominalservice charge is required to cover shipping andhandling.TRANSISTOR/DIODE TESTERMODEL DT-100When returning merchandise for repair,please include proof of purchase, a brief letterof explanation of problem, and sufficientpacking material. Before returning anymerchandise please call our servicedepartment at (847) 541-3800 to obtain areturn authorization number (RMA).Elenco Electronics, Inc.150 W. Carpenter AvenueWheeling, IL 60090(847) 541-3800http://www.elenco.come-mail: elenco@elenco.comLesson ManualElenco Electronics, Inc.Copyright © 1988 Elenco Electronics, Inc. REV-D 753115Revised 2001

FEATURESDiode Mode:1. Checks all types of diodes - germanium, silicon, power, lightemitting (LEDs), and zener.2. Indicates the cathode or anode leads of the diode.3. Operates in circuit with resistors as low as 5kW.SCHEMATIC DIAGRAMTransistor Mode:1. Checks all types of transistors - germanium, silicon, power, RF,audio, switching, and FETs.2. Identifies NPN and PNP types, PN or NP junctions.3. High gain circuit, can test transistors in circuits with base orcollector resistors as low as 100W.4. Measures relative beta of two transistors.-1- -6-

DT-100 PARTS LISTResistors 5% 1/4WQty. Symbol Value Color Code Part #1 R14 100W brown-black-brown-gold 1310002 R5, R6 220W red-red-brown-gold 1322002 R1, R10 330W orange-orange-brown-gold 1333001 R13 1kW brown-black-red-gold 1410001 R7 5.6kW green-blue-red-gold 1456001 R12 10kW brown-black-orange-gold 1510001 R8 18kW brown-gray-orange-gold 1518002 R2, R3 33kW orange-orange-orange-gold 1533001 R9 47kW yellow-violet-orange-gold 1547001 R11 100kW brown-black-yellow-gold 1610001 R4 330kW orange-orange-yellow-gold 1633001 R15 100kW Variable Potentiometer 192611CapacitorsQty. Symbol Value Description Part #1 C6 0.001mF (102) Discap 2310363 C2, C3, C5 0.01mF (103) Discap 2410312 C1, C4 10mF Lytic 271045SemiconductorsQty. Symbol Value Description Part #1 D1 1N4001 Diode 3140011 Q5 MPS A70 Transistor 3200704 Q1 - Q4 2N3904 Transistor 3239041 IC1 555 Integrated Circuit 3305555 L1 - L5 Light Emitting Diode 350002Qty. Description Part #1 PC Board 5111001 Switch Push Button 5400012 Switch DPDT 5411111 Battery Snap 5900981 Panel Front 6141001 Knob 6220091 Case 6232405 Spacer LED 6241114 Screw 4-40 x 1/4” 6414301 Nut Pot 7mm 6441011 Flat Washer 6451014 Nut 4-40 644400MiscellaneousQty. Description Part #1 Lockwasher 5/16” Int. 6461011 Socket 8-Pin IC 6640081 Transistor Socket 6645001 Clip Black 6800011 Clip Red 6800021 Clip Green 6800031 Clip Yellow 6800041 Wire Black 20 ga. 8131101 Wire Red 20 ga. 8132101 Wire Yellow 20 ga. 8134101 Wire Green 20 ga. 8135101 Wire Blue Solid 22 ga. 814620OPERATING INSTRUCTIONSThe DT-100 is a dynamic transistor and diode tester. It features incircuittesting and polarity indicators for both transistors anddiodes. To activate the DT-100, remove the four front mountingscrews and install a fresh 9V battery.Diode Testing1. Place the switch in the diode position.2. Connect the diode to the red and black leads.3. Push in the test switch. One diode LED should blink and identifywhether the cathode or anode is connected to the diode (red) lead.4. If both LED lamps blink, then the diode is shorted.5. If neither LED lamps light, then the diode is open.Transistor Mode:The DT-100 can measure transistors in or out of circuit.identify NPN or PNP by a simple adjustment.Transistor Testing - Out of Circuit1. Place the switch in the transistor position.It will2. Place the transistor in the socket or attach it to the C, B, and Eleads.3. Push in the test button. Adjust the base current control so thatthe OK LED lights up. This indicates a good transistor.4. If the OK lamp doesn’t light, adjust the base current control sothat either the NP or PN LED lights up. This happens at theminimum or maximum position of the control setting. This willindicate transistor type. Place the switch to the NPN position ifthe NP lamp lights up, or place the switch to the PNP position ifthe PN lamp is lit.-5-5. If no lamps light up, then the transistor is open or we have notidentified the base lead. Repeat assuming another lead at thebase.-2-

6. When the transistor is shown to be OK, the base current controlgives an indication of transistor beta. The lower the settingrelative to another transistor, the higher the beta. Lamps NPand PN measure base current. Higher base current results in abrighter LED. It also indicates if current is entering or leavingthe base, thus, NP or PN respectively will light.Transistor Testing - In CircuitThe DT-100 will test transistors in circuit, provided the base biasingresistance is greater than 100W. Simply follow the previousprocedure for testing out of circuit transistors. Do not apply powerto the circuit of the transistor or diode under test. The DT-100 willsupply the necessary power.CHECKING OUT YOUR TRANSISTOR/DIODE TESTERThe following is a simple procedure for testing your DT-100.Diode Operation:1. Place the switch in the diode position. Short the black and redleads together and push in the test button. The diode test LEDsshould alternately go on at about a 1Hz rate.2. Connect the red and black leads to any good diode. Only one LEDshould flash, identifying the red lead connection (anode orcathode). Reversing the leads should cause the other LED to flash.Transistor Operation:1. Place the switch in the transistor position. Short the yellow (B)and black (E) leads together. Press the test button. Vary thebase current control. The NP lamp should light with the switchin the NPN position and the PN lamp when the switch is in thePNP position.2. Place a known good transistor in the test socket with the Emitterin E, Base in B and Collector in C pins. Be sure none of theleads are shorting. Vary the base current control. The OK LEDshould light up. Note that on the NPN transistor, the NP lampalso will glow very slightly. This indicates the base current, andthus lower intensity. The base current control should beadjusted for the lowest setting with the OK lamp glowing.THEORY OF OPERATIONNote the schematic diagram on page 6. The test transistor in thiscircuit is an NPN. Adjusting the variable resistor will cause theNPN LED to light up indicating that the base current is flowing. Theoutput of the test transistor is fed to amplifiers Q2 and Q3. Theoutput of Q2 is feedback in phase to the base of the test transistorcausing the circuit to oscillate. Part of the oscillations are fed to apower rectifier, Q5, which switches on the OK LED indicator.The design configuration is such that in-circuit transistors can bemeasured, provided that the base and collector resistors aregreater than 100W.When measuring PNP transistors, the power supplied to the testtransistor is reversed via the NPN/PNP switch. Therefore, the PNLED will light up.Varying the base current control will reduce the base current. Thelower the base current, the higher the gain of the transistor undertest. Comparative tests of two transistors’ gain (beta), can bemade by observing the dial setting or the intensity of the base LEDdiode. The lower the setting with the PN LED lit, the higher thebeta of that transistor.On diode operation, power is applied to IC1. This causes thecircuit to oscillate at about a 1Hz rate. Placing a diode in serieswith the LED indicators will cause a current to flow, depending onthe direction of the diode. Thus, the red test lead will identify thecathode or anode of the diode via the LED readout. Transistor Q4reverses the current flow in this circuit.All types of diodes may be tested: Silicon, germanium, LEDs orzeners over 6 volts. Zener diodes under 6V causes the secondLED to glow at lower intensity, indicating that zener breakdown hasoccurred.-3--4-