What forward voltage is needed to bias a germanium diode compared with a silicon diode?

A germanium diode typically needs about 0.3 V forward bias, while a silicon diode typically needs about 0.7 V.

How do analog resistance readings differ from digital multimeter readings when testing diodes?

Analog meters may apply a different test voltage and polarity than digital multimeters, so diode resistance readings can differ substantially.

What should be identified first when testing a MOSFET?

First identify whether it is an N-channel or P-channel device and determine its pinout before applying test leads.

Free online course Advanced electronics

Duration of the online course: 7 hours and 29 minutes

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Boost your electronics troubleshooting skills with a free online course on diodes and transistors, plus practice questions and a completion certificate.

In this free course, learn about

Fundamentals of semiconductor electronics (diodes, transistors, and common applications)
Junction diode structure and materials (how a PN junction is made)
Germanium diode forward-bias threshold voltage (minimum bias required)
Causes of diode characteristic damage (overcurrent, overheating, reverse breakdown, mishandling)
Analog vs digital resistance measurements: behavior on semiconductors and meter test currents
First widely used solid-state component and its role in electronics history
Transistor purpose as a switch/amplifier and identification of its three terminals
Typical silicon B-E junction forward voltage in a transistor (approximate V_BE)
Real-world alternator failure diagnosis from a road-trip case study (root cause and symptoms)
Historical significance of FET invention and why it mattered versus earlier devices
JFET gate-source cutoff voltage meaning and how it relates to channel pinch-off
First step in MOSFET testing: identify device type/pinout and check gate insulation/leakage

About the free online course

Take your electrical know-how beyond basic wiring and gain confidence working with the electronic components you meet in modern systems. This free online course helps you build a practical understanding of solid-state devices so you can diagnose faults faster, measure more accurately, and make smarter repair decisions on real equipment.

You will connect key concepts to hands-on technician thinking: how junction diodes are formed, what forward bias really means in practice, and why different materials change typical voltage behavior. You will also learn what kinds of stress and misuse can permanently alter a diode’s characteristics, giving you insight into common failure modes you may see in the field.

Measurement skills matter as much as theory, so the course clarifies the real differences between resistance checks made with an analog meter versus a digital multimeter, and what those differences imply when you are testing components in or out of circuit. From there, you move into the devices that power switching and amplification across everything from control boards to automotive and industrial electronics. You will understand what a transistor does, how to identify its leads, and what voltage to expect across critical junctions so your tests have clear pass/fail meaning.

The learning is reinforced with scenario-style questions, including a troubleshooting story tied to an alternator failure, designed to sharpen your ability to reason from symptoms to root cause. You will also explore why field effect transistors became such a milestone in electronics, then build practical awareness of JFET behavior and MOSFET testing priorities, including what you must determine first before drawing conclusions.

By the end, you will be better prepared to interpret meter readings, protect sensitive components, and approach electronics faults methodically. It is a focused step forward for electricians and technicians who want stronger professional skills in diagnostics and modern electronic systems.

Course content

Video class: Basic Electronics Part 3 7h29m
Exercise: _What is a junction diode made of?
Exercise: _What is the minimum bias voltage required for forward biasing a germanium diode?
Exercise: _What can damage diode characteristics?
Exercise: _What is the difference between taking resistance measurements with an analog meter and a digital multimeter?
Exercise: _What is the first real component that was invented in the solid state form?
Exercise: _What is the function of a transistor and what are the three leads called?
Exercise: _What is the approximate forward bias voltage across the base emitter junction of a silicon transistor?
Exercise: _What was the cause of the alternator failure in the motorhome during the road trip from San Diego to Connecticut?
Exercise: _What is the historic significance behind the invention of field effect transistors (FETs)?
Exercise: _What is the gate source cut off voltage in a JFET?
Exercise: _What is the first thing you have to determine when testing a mosfet?

Free online courses on Advanced Electronics

Learn aboutAdvanced Electronics

Explore free online Advanced Electronics courses and build in-demand skills in circuit design, semiconductor devices, digital systems, embedded technology, and signal processing. Learn at your own pace with expert-led lessons, practical projects, and flexible study options. Enroll today and earn a certificate to showcase your knowledge.