https://comfilewiki.co.kr/en/ 2026-06-10T22:56:18+00:00 https://comfilewiki.co.kr/en/ https://comfilewiki.co.kr/en/lib/exe/fetch.php?media=wiki:logo.png text/html 2026-06-10T20:42:29+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:analog_inputs&rev=1781124149&do=diff Analog Input Circuits Most microcontrollers and CUBLOC modules provide analog input pins, but connecting a sensor directly to an ADC input is usually not a good idea. This is one of the most common mistakes made by beginners. Sensor wiring often runs through electrically noisy environments. Noise, static electricity, and voltage surges can all find their way back to the controller through these wires. In severe cases, the MCU itself may be damaged. text/html 2026-06-10T20:33:12+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:board_design_tips&rev=1781123592&do=diff Additional PCB Design Tips If you are designing a board based on a microcontroller or a CUBLOC module, the following guidelines can help improve reliability and reduce noise-related problems. Generate the 5V supply on the same board as the MCU. A common mistake is to generate 5V on one board and then run that 5V through a cable to another board containing the MCU. text/html 2026-06-10T19:00:33+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:capacitors&rev=1781118033&do=diff Capacitors A capacitor is a component that can store a small amount of electrical energy for a short period of time. Capacitors are one of the most important tools for reducing electrical noise. They act like tiny energy reservoirs, absorbing unwanted disturbances and helping keep the power supply stable. text/html 2026-06-10T20:34:02+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:common_mistakes&rev=1781123642&do=diff Other Things to Watch Out For Moisture and electronics do not get along. If your board will be used in greenhouses, boats, fish farms, coastal areas, or anywhere that experiences heavy condensation, moisture protection should be considered. In many cases, it is not necessary to coat the entire PCB. Applying a conformal coating to sensitive areas, especially fine-pitch components such as QFP packages, is often enough. text/html 2026-06-10T21:11:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:control_panel_noise&rev=1781125916&do=diff Noise control is very important in systems that use control panels, PLCs, HMIs, motors, and drives. When a motor starts or stops, the noise it creates can affect nearby sensor signals, PLCs, and HMIs. In some cases, the system may behave strangely even though the program itself has no problem. text/html 2026-06-10T20:28:48+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:decoupling_caps&rev=1781123328&do=diff Decoupling Capacitors: The Most Important Noise-Fighting Component If you've designed PCBs before, you've probably been told to place a 0.01 µF to 0.1 µF capacitor near every IC power pin. Most engineers follow this rule, but many never stop to ask why. text/html 2026-06-10T20:37:07+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:good_design_examples&rev=1781123827&do=diff An Example of a Well-Designed Board I found the board shown above on the Internet. Even at a glance, it's clear that noise immunity was an important design goal. The input circuits are isolated from the rest of the system. This helps prevent external noise from reaching the controller and is one of the most effective ways to improve reliability in industrial environments. text/html 2026-06-10T21:02:57+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:grounding&rev=1781125377&do=diff Checking Your Ground Connection Throughout this book, we've talked about the importance of grounding for noise control. But how do you know if your ground connection is actually working? Most wall outlets have a ground connection. Unfortunately, that does not guarantee that the outlet is properly grounded. text/html 2026-06-10T20:48:13+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:index&rev=1781124493&do=diff Practical Noise Control Lessons for Electrical Engineers Noise is a challenge that every electrical and electronics engineer faces throughout their career. Designing products that can operate reliably in noisy environments requires both practical experience and a solid understanding of noise-related issues. text/html 2026-06-10T20:54:46+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:isolated_io&rev=1781124886&do=diff What Is Isolation? Isolation means completely separating one part of a circuit from another. A common misconception is that simply adding an optocoupler creates an isolated system. In reality, true isolation requires the power supply, input circuits, and output circuits to be separated from each other. text/html 2026-06-10T19:45:31+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:noise_filters&rev=1781120731&do=diff Noise Filters Engineers often recommend adding several components to the power input of a device to reduce electrical noise (EMI). The circuit can look a bit intimidating, especially if you're not familiar with electronics. Fortunately, there is an easier way. text/html 2026-06-10T20:05:31+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:noise_modes&rev=1781121931&do=diff Common Forms of Noise Noise does not always appear in the same way. Sometimes it shows up as a sudden spike, and other times it appears as a continuous disturbance mixed into a signal. One common type of noise is an impulse. An impulse is a very short but very large voltage spike. It often occurs when motors start, relays switch on or off, or inductive devices such as coils are energized. text/html 2026-06-10T20:17:42+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:noise_overview&rev=1781122662&do=diff A Simple Approach to Noise Control When dealing with noise, it helps to think in three steps. First, try to reduce noise where it is generated. A relay, contactor, or other switching device can create sparks when it turns on or off. These sparks generate noise that can affect nearby equipment. Devices such as spark suppressors help reduce noise before it becomes a problem. text/html 2026-06-10T20:00:29+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:noise_types&rev=1781121629&do=diff What Is Electrical Noise? Electrical noise is something that every engineer eventually runs into. It can be frustrating, but don't ignore it. The more you understand noise, the easier it becomes to build reliable products. Many mysterious problems in the field turn out to be noise-related. Random resets, communication failures, incorrect measurements, and equipment that works fine in the lab but fails at the customer's site are often caused by noise. text/html 2026-06-10T20:23:20+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:pcb_layout&rev=1781123000&do=diff PCB Design Guidelines Noise control does not start after the PCB is finished. It starts during the design stage. A few simple design habits can prevent many noise-related problems later. Keep traces as short as possible. Long traces have higher inductance and are more likely to pick up or radiate noise. This becomes especially important for high-speed signals. In general, shorter traces are better. text/html 2026-06-10T19:48:59+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:powerinput&rev=1781120939&do=diff A Typical Power Input Setup In industrial equipment, the power input section is often built using the following components: * Circuit Breaker – Protects against overloads and short circuits * SPD (Surge Protection Device) – Protects against surge voltages text/html 2026-06-10T20:56:02+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:single_board_plc&rev=1781124962&do=diff Designing a Single-Board PLC: Things to Watch Out For Many companies start with a PLC-based system and successfully sell their products for years. Eventually, someone looks at the bill of materials and notices that the PLC is one of the most expensive parts of the system. text/html 2026-06-10T20:19:54+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:snubber_usage&rev=1781122794&do=diff Using Spark Suppressors (RC Snubbers) If you connect external relays, contactors, solenoids, or other inductive loads to your system, a spark suppressor (RC snubber) should be considered essential. Whenever a relay switches on or off, a voltage spike is generated. This spike creates electrical noise that can travel through the wiring and affect other parts of the system. text/html 2026-06-10T19:30:25+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:spark_snubbers&rev=1781119825&do=diff Spark Suppressors (Snubbers) Components that contain coils, such as relays, contactors, solenoids, and motors, can generate electrical noise when they are switched on or off. When current flowing through a coil is suddenly interrupted, the energy stored in the coil must go somewhere. As a result, a brief but potentially high voltage spike can be generated. This can cause arcing, sparks at the contacts, and electrical noise that may interfere with nearby electronic circuits. text/html 2026-06-10T19:43:55+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:spd&rev=1781120635&do=diff Surge Protection Devices (SPD) Sometimes you may hear someone say, “The PC keeps freezing whenever it rains,” or “Equipment suddenly stopped working after a thunderstorm.” In many cases, a surge may be the cause. A surge is a sudden burst of electrical energy caused by lightning, electrical switching, or other unpredictable events. Just as we cannot stop lightning from occurring, we cannot completely prevent surges from happening. text/html 2026-06-10T19:02:59+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:tvs&rev=1781118179&do=diff TVS Diodes Have you ever felt a small electric shock when shaking someone's hand or touching a metal object? That is static electricity. Electronic devices can experience similar events when cables are plugged in, unplugged, or touched by people. Connectors such as RS-232, RS-485, and USB ports are especially vulnerable because they are frequently connected and disconnected. In some cases, a sudden voltage spike can enter through these connections and damage sensitive electronic components. text/html 2026-06-10T19:05:15+00:00 Anonymous (anonymous@undisclosed.example.com) https://comfilewiki.co.kr/en/doku.php?id=noise_book:varistors&rev=1781118315&do=diff Varistors (MOVs) A varistor is a protective component whose resistance changes depending on the applied voltage. Under normal operating conditions, it has very high resistance and allows almost no current to flow through it. However, when the voltage suddenly rises above a certain level, its resistance drops dramatically.