TRANSISTOR/DIODE TESTER MODEL DT-100 Lesson Manual ELENCO® Copyright © 2012, 1988 Elenco® Electronics, Inc.
FEATURES Diode Mode: 1. Checks all types of diodes - germanium, silicon, power, light emitting (LEDs), and zener. 2. Indicates the cathode or anode leads of the diode. 3. Operates in circuit with resistors as low as 5kΩ. Transistor 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 or collector resistors as low as 100Ω. 4.
OPERATING INSTRUCTIONS The DT-100 is a dynamic transistor and diode tester. It features incircuit testing and polarity indicators for both transistors and diodes. To activate the DT-100, remove the four mounting screws from the bottom and install a fresh 9V battery. Diode Testing 1. 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 identify whether the cathode or anode is connected to the diode (red) lead. 4.
6. When the transistor is shown to be OK, the base current control gives an indication of transistor beta. The lower the setting relative to another transistor, the higher the beta. Lamps NPN and PNP measure base current. Higher base current results in a brighter LED. It also indicates if current is entering or leaving the base, thus, NPN or PNP respectively will light. Transistor Testing - In Circuit The DT-100 will test transistors in circuit, provided the base biasing resistance is greater than 100Ω.
THEORY OF OPERATION Note the schematic diagram on page 6. The test transistor in this circuit is an NPN. Adjusting the variable resistor will cause the NPN LED to light up indicating that the base current is flowing. The output of the test transistor is fed to amplifiers Q2 and Q3. The output of Q2 is feedback in phase to the base of the test transistor causing the circuit to oscillate. Part of the oscillations are fed to a power rectifier, Q5, which switches on the OK LED indicator.
DT-100 PARTS LIST Resistors 5% 1/4W Qty. r1 r2 r2 r1 r1 r1 r1 r2 r1 r1 r1 r1 Symbol R14 R5, R6 R1, R10 R13 R7 R12 R8 R2, R3 R9 R11 R4 R15 Value 100Ω 220Ω 330Ω 1kΩ 5.6kΩ 10kΩ 18kΩ 33kΩ 47kΩ 100kΩ 330kΩ 100kΩ Color Code brown-black-brown-gold red-red-brown-gold orange-orange-brown-gold brown-black-red-gold green-blue-red-gold brown-black-orange-gold brown-gray-orange-gold orange-orange-orange-gold yellow-violet-orange-gold brown-black-yellow-gold orange-orange-yellow-gold Variable Potentiometer Qty.
SCHEMATIC DIAGRAM -6-
TWO YEAR WARRANTY All ELENCO® models are guaranteed for two full years on all parts and service. For the first 3 months, your transistor/diode tester is covered at absolutely no charge. For the remaining 21 months, a nominal service charge is required to cover shipping and handling. When returning merchandise for repair, please include proof of purchase, a brief letter of explanation of problem, and sufficient packing material.
