Only Wonder Knows

Only Wonder Knows is a newsletter focused on electronic design, offering insights into signal integrity, manufacturing PCBs, oscilloscope measurements, technical documentation, and practical tips for engineers. It delves into specific issues like stubs, distortion measurement, and the use of open-source tools, aiming to improve understanding and practices in electronic design.

Electronic Design PCB Manufacturing Signal Integrity Measurement Techniques Technical Documentation Circuit Calibration Schematic Drawing Tool Evaluations Design Validation High-Speed Design

The hottest Substack posts of Only Wonder Knows

And their main takeaways

It's Christmas time

78 implied HN points β€’ 22 Dec 23
β›ͺ Faith & Spirituality Christianity Spiritual reflection
  1. The story of Christmas is about the birth of an extraordinary child, understood by shepherds as a significant event.
  2. Understanding the meaning of something allows for a deeper comprehension of its impact and significance.
  3. The baby born on Christmas was believed to be God in human form, with the power to change history and lives.

Calibrating circuits

19 implied HN points β€’ 09 Feb 24
πŸ”¬ Science Physics Chemistry Engineering Technology Research
  1. Calibration of circuits can be a useful solution but it's important to know when it is necessary and when it's not.
  2. Understanding how components like sensors and resistors behave in different conditions is crucial before considering calibration.
  3. Before deciding to calibrate electronic components, a detailed technical and economic analysis should be conducted to ensure it is a suitable solution.

Validating PCAs (1)

78 implied HN points β€’ 15 Sep 23
πŸ•Ή Technology Engineering Electronics Testing Validation Design
  1. Validating designed electronics is as important as designing them.
  2. The U-test model involves generating controlled stimulus and checking responses to ensure proper functioning of circuits.
  3. Different types of tests like design, manufacturing, integration, and regression tests play a crucial role in validation processes.
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Fuses

39 implied HN points β€’ 17 Nov 23
πŸ•Ή Technology Electronics Devices Components Circuits Design
  1. Fuses are essential components for providing protection in electronic circuits by blowing up when the current exceeds a certain threshold.
  2. Fuses have specific ratings like amperage and voltage, and their behavior can be affected by factors like temperature and pulse energy.
  3. Understanding the details of fuses is crucial for designing reliable circuit boards and ensuring proper functionality.

How things fail

39 implied HN points β€’ 03 Nov 23
πŸ•Ή Technology Testing Reliability Engineering
  1. Testing things to failure can reveal weaknesses and help improve reliability.
  2. The HALT test is an effective method to stress test products and discover design flaws.
  3. Each weakness identified in the HALT test presents an opportunity to enhance product reliability.

Lab notebooks

58 implied HN points β€’ 01 Sep 23
πŸ•Ή Technology Electronics Note Taking Debugging Tools
  1. Recording funny things in lab notebooks can save time and provide valuable insights for future work.
  2. Using a notebook for design work, organizing content, and including references can help centralize information.
  3. Taking oscilloscope captures, naming signals, and recording measurement values are important steps for effective debugging.

Transmission line explorations - deeper investigations

39 implied HN points β€’ 20 Oct 23
πŸ•Ή Technology Electronics Manufacturing Materials Simulation Engineering
  1. Establish a close relationship with the PCB manufacturer to discuss concerns and ask for expected ranges.
  2. Consider ordering a PCB carefully as design complexity increases, requiring more aspects to be taken into account.
  3. Copper roughness, dielectric materials, and DK uniformity are crucial factors to consider in PCB design for high-speed signals.

Oscilloscope measurements

78 implied HN points β€’ 14 Jul 23
πŸ•Ή Technology Electronics Equipment Tools
  1. Oscilloscopes have been crucial tools in electronics for a long time, helping engineers understand and test signal changes.
  2. Digital oscilloscopes offer advanced features like horizontal position adjustment, holdoff function, and memory segmentation for better measurement control.
  3. Trigger modes on oscilloscopes, like 'auto' and 'normal,' serve different purposes in displaying and analyzing traces.

Manufacturing PCBs with controlled impedance

98 implied HN points β€’ 02 Jun 23
πŸ•Ή Technology Manufacturing Engineering Quality control
  1. Manufacturing PCBs with controlled impedance involves extra cost and needs to be well understood and justified.
  2. To determine when controlled impedance of PCB traces is needed, consider factors like trace width, dielectric material thickness, and manufacturing tolerances.
  3. Measuring characteristic impedance in PCBs involves complex processes, manual testing, and cost implications that should be discussed with the manufacturer.

Driving fans

98 implied HN points β€’ 25 May 23
πŸ”¬ Science Physics Engineering Devices Specifications
  1. Understanding basic physics is crucial when dealing with fan systems.
  2. The relationship between air flow and air pressure in fan systems is not always linear.
  3. When selecting a fan for a system, consider factors like power consumption, flow specifications, and current consumption.

Chopper amplifiers: history and present

19 implied HN points β€’ 15 Dec 23
πŸ”¬ Science Electronics Engineering Physics Circuits
  1. Chopper amplifiers are a technique to reduce DC offset and low frequency noise in amplifiers.
  2. Historically, chopper amplifiers have been implemented using innovative methods like optical chopping with cadmium sulfide light-dependent resistors.
  3. Contemporary engineers can refer to Jim Williams' design for an ultrahigh performance instrumentation amplifier that resembles the old chopper amplifier concept.

Summer break

58 implied HN points β€’ 28 Jul 23
  1. The newsletter will be on a break for August.
  2. The author plans to return with new posts by September 1st.
  3. During the rest time, there is a task suggested: Love truth, practice good, and build beauty.

Stubs (I)

58 implied HN points β€’ 21 Jul 23
πŸ”¬ Science Physics Engineering Analysis Simulation Design
  1. Stubs in transmission lines can cause reflections and affect signal quality.
  2. The impact of a stub can be minimized by understanding its notch frequencies.
  3. For frequencies below half of the notch frequency, the effect of a stub can be ignored.

Measuring distortion

58 implied HN points β€’ 19 May 23
πŸ”¬ Science Characterization Measurement
  1. When working with non-linear systems, be cautious and pay attention to distortion.
  2. Measuring distortion in systems may require using techniques like injecting two tones.
  3. Characterizing distortion involves understanding how system limitations affect harmonic levels.

Time response of first order systems

19 implied HN points β€’ 27 Oct 23
πŸ”¬ Science Physics Experiments Measurement
  1. When measuring a system's response time, make sure to wait for at least five time constants to reach a stable state.
  2. First order systems have a unique time response that can be calculated using simple expressions.
  3. Extracting the time constant of a system involves analyzing data, normalizing measurements, and ensuring a good fit to confirm the system's behavior.

Transmission line explorations

19 implied HN points β€’ 06 Oct 23
πŸ•Ή Technology Materials Manufacturing
  1. When designing for high speeds, it's important to investigate the terrain, understand the influencing factors, and make informed decisions.
  2. For differential transmission lines, attention to impedance match and signal attenuation is crucial for maintaining signal integrity.
  3. Factors like coupling effects, dielectric thickness, solder mask, copper thickness, and material choice all play key roles in high-speed design outcomes.

How good conductors are copper traces?

19 implied HN points β€’ 29 Sep 23
πŸ•Ή Technology Engineering
  1. Trace resistance is proportional to the number of squares it contains
  2. The resistivity of a square of copper of 1-oz at 25 ΒΊC is 500 ΞΌΞ©
  3. When designing for high currents, consider trace width, self-heating, IR drop, and vias

Validating PCAs (2)

19 implied HN points β€’ 22 Sep 23
πŸ”¬ Science Validation
  1. Validating the design of a Power Supply Unit (PSU) requires analytical worst case support.
  2. When testing memory, differentiate between design validation and assembly test for optimal coverage.
  3. For precise analog signals, validate design with analytical worst case analysis and perform functional tests for manufacturing validation.

Stubs (II)

19 implied HN points β€’ 28 Jul 23
πŸ”¬ Science Engineering Simulation Analysis Design
  1. In time domain analysis of stubs, keeping stub delay less than half the signal rise time leads to undistorted waveforms.
  2. Rules of thumb for stub analysis suggest keeping stub delay below half the signal rise time for minimal effect.
  3. In high-speed designs, stubs usually aren't an issue if good engineering practices are followed, but caution is needed when boards are very high-speed.

Coming soon

19 implied HN points β€’ 18 Apr 23
πŸͺ‘ Design Newsletter
  1. A design tips newsletter called 'The wonder of electronic design' is coming soon
  2. The newsletter is by Luis Miguel Brugarolas
  3. Subscribe to 'Only Wonder Knows' on onlywonderknows.substack.com

Discrete-time first order system implementation

0 implied HN points β€’ 10 Nov 23
πŸ•Ή Technology Engineering Implementation
  1. The discrete-time first order system structure involves a combination of current and past input signals to maintain unity gain.
  2. The value of multiplying factor K in the structure determines the speed of the system's response to input changes.
  3. Implementing the filter in digital systems can involve using integer arithmetic and tricks like shifting, making it practical for FPGA or CPU implementations.

More first order systems

0 implied HN points β€’ 24 Nov 23
πŸ”¬ Science Systems Mathematics
  1. Linear time-invariant systems are characterized by impulse or step response and frequency response.
  2. Measurement of systems is done using step response and response to sinusoids of different frequencies.
  3. First order systems are characterized by gain at zero frequency and either time constant or corner frequency.