
TRANSISTOR/DIODE TESTER
MODEL DT-100
Lesson Manual
ELENCO
®
Copyright © 2012, 1988 REV-G 753115
Elenco®Electronics, Inc. Revised 2012

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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. Measures relative beta of two transistors.

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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. 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. It will identify
NPN or PNP by a simple adjustment.
Transistor Testing - Out of Circuit
1. Place the switch in the transistor position.
2. Place the transistor in the socket or attach it to the C, B, and E
leads.
3. Push in the test button. Adjust the base current control so that
the OK LED lights up. This indicates a good transistor.
4. If the OK lamp doesn’t light, adjust the base current control so
that either the NPN or PNP LED lights up. This happens at the
minimum or maximum position of the control setting. This will
indicate transistor type. Place the switch to the NPN position if
the NPN lamp lights up, or place the switch to the PNP position
if the PNP lamp is lit.
5. If no lamps light up, then the transistor is open or we have not
identified the base lead. Repeat assuming another lead at the
base.