lcamtuf’s thing

lcamtuf’s thing explores the intricacies of modern and traditional electronics, challenges and insights from moving to a rural area, the basics and applications of electronic components, the impact of AI in understanding technology, the philosophy of effective altruism, and reflections on corporate life and technology's evolution. It blends technical tutorials with personal experiences and broader technological discussions.

Electronics Rural Living and Challenges Electronic Components and Circuits AI and Technology Effective Altruism Corporate Life Technology Evolution

The hottest Substack posts of lcamtuf’s thing

And their main takeaways

Against the hydraulic analogy

3469 implied HN points • 27 Dec 24
🕹 Technology Electronics Education Engineering Analogies Learning
  1. The hydraulic analogy, which compares electrical circuits to water systems, is often misleading. It can create confusion, especially when learning complex components like semiconductors.
  2. While analogies can aid in understanding, they need to remain accurate as you learn more advanced concepts. The hydraulic analogy can break down and lead to misunderstandings.
  3. When students encounter flaws in the hydraulic analogy, it may cause them to forget the basics and start over, making the learning process harder than it needs to be.

A 15-minute intro to resin casting

4693 implied HN points • 21 Dec 24
🕹 Technology Engineering Manufacturing Prototyping DIY Materials
  1. Resin casting involves making a mold and pouring liquid plastic into it. This method allows you to create exact replicas of items, capturing all their details.
  2. Compared to 3D printing, resin casting can produce stronger and more durable parts. It also gives a finer finish since the liquid can fill every tiny detail of the mold.
  3. The process includes making a flexible mold from silicone, applying a release agent, and carefully pouring in the resin. It's important to manage air bubbles for the best results.

The marvelous disappearing capacitor

4285 implied HN points • 07 Dec 24
🕹 Technology Electronics Engineering Physics Signal Processing Innovation
  1. Bootstrapping can significantly improve photodiode amplifier performance by minimizing the impact of parasitic capacitance. This helps in amplifying fast-changing signals better.
  2. A voltage follower in the circuit helps keep the photodiode at the same voltage, preventing internal charging and making it act like an ideal current source.
  3. While bootstrapping boosts performance, real-life limitations exist, like bandwidth and impedance, which need to be considered for accurate designs.

A 15-minute intro to involute gears

6938 implied HN points • 17 Nov 24
🕹 Technology Engineering Manufacturing Design Mathematics Mechanics
  1. Involute gears are used in many everyday items like toys and cars. Their special shape helps them work smoothly and efficiently.
  2. These gears have specific properties that reduce friction and vibrations, allowing them to transfer motion without problems. This ensures they work together seamlessly.
  3. Understanding the design of involute gears helps in creating various gear types, even unique shapes, making it easier to innovate in mechanical engineering.

Lies, damned lies, and photodiodes

2040 implied HN points • 09 Dec 24
🕹 Technology Electronics Engineering Optics Sensors Measurement
  1. Photodiodes can have a wide range of response speeds, and the advertised specs often don't tell the whole story. It's important to understand how they are tested, as this can affect their performance.
  2. When building precise measurement devices with photodiodes, two types of currents play a role. One is fast, while the other can take much longer to settle down, impacting the overall signal quality.
  3. Using techniques like reverse bias can improve performance, but some effects are inherent to the photodiodes themselves. Understanding these limitations is key for achieving accurate measurements.
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Building a phosphorescence detector

2652 implied HN points • 27 Nov 24
🔬 Science Physics Engineering Research Technology Materials
  1. There isn't much information available on natural phosphorescence, so creating a detector can help explore its presence in everyday items.
  2. The device design prioritizes speed and sensitivity to detect phosphorescence briefly brought out by UV light, using specific electronics like photodiodes and amplifiers.
  3. Experimenting with common household materials showed that some items, like powdered milk and natural ruby, exhibit weak phosphorescence, although many other items didn't show any notable glow.

Goodbye, real electronic lab kits?

4285 implied HN points • 02 Dec 23
🕹 Technology Electronics Education STEM Toys Learning
  1. Traditional electronic lab kits are disappearing, replaced by newer products like Snap Circuits
  2. The older kits offered a hands-on, educational experience with detailed schematics and components
  3. Newer products like Snap Circuits focus more on quick gratification than teaching electronics concepts

Gemini: how did we end up here?

2652 implied HN points • 02 Mar 24
🕹 Technology AI Ethics Language Models Big Tech Content Moderation
  1. The development of large language models (LLMs) like Gemini involves mechanisms like reinforcement learning from human feedback, which can lead to biases and quirky responses.
  2. Concerns arise about the use of LLMs for automated content moderation and the potential impact on historical and political education for children.
  3. The shift within Big Tech towards paternalistic content moderation reflects a move away from the libertarian culture predominant until the mid-2010s, highlighting evolving perspectives on regulating information online.

DACs and ADCs, or there and back again

1836 implied HN points • 19 Feb 24
🕹 Technology Electronics Microcontrollers
  1. Digital circuits often require digital-to-analog and analog-to-digital converters to interface with the physical world.
  2. For digital-to-analog conversion, architectures like binary-weighted DACs and R-2R DACs are commonly used, but the latter addresses practical issues with resistor values.
  3. Analog-to-digital converters (ADCs) can be complex, involving methods like flash ADCs and slope-based ADCs, which use principles like comparison, integration, and sigma-delta modulation for accurate voltage readings.

Resistors are out to get ya

2652 implied HN points • 28 Nov 23
🔬 Science Electronics Components Circuits Amplifiers
  1. Some components in electronics, like resistors, may not behave exactly as expected especially at high frequencies.
  2. Parasitic impedance and capacitance in resistors can affect circuit performance, especially in applications like feedback loops for operational amplifiers.
  3. Using a two-stage amplifier can help mitigate issues caused by resistor parasitics and ensure better signal integrity.

Energy in electronic circuits

2244 implied HN points • 16 Oct 23
🔬 Science Physics Electronics Energy Circuits
  1. Designing electronic circuits has become more stringent over the years due to advancements in technology.
  2. Understanding how energy travels through electronic circuits is crucial for circuit stability and efficiency.
  3. High-speed signals in electronic circuits can lead to significant energy expenditure and signal integrity issues.

MCU land, part 9: ST7789, the final frontier

1836 implied HN points • 09 Sep 23
🕹 Technology Microcontrollers Graphics Programming Electronics Embedded Systems
  1. Driving a 2.8" 240x320 IPS panel with a Microchip SAM S70 Cortex-M7 MCU can be surprisingly simple.
  2. The steps to set up the ST7789 display controller involve minimal and straightforward commands like hardware reset and configuration for color mode.
  3. Generating image data for the display in 16 bpp RGB565 color mode is achievable through tools like ImageMagick.

Building a decent microphone amplifier

2856 implied HN points • 30 Mar 23
🕹 Technology Electronics Amplifiers Circuit Design
  1. Building a good far-field microphone kit requires attention to microphone sensitivity and selecting a suitable op-amp.
  2. Creating a basic but effective circuit architecture for a microphone amplifier involves understanding current-to-voltage conversion and noise reduction techniques.
  3. To avoid issues like over-amplification and background noise, solutions such as manual gain control and automatic gain control (AGC) can be implemented in microphone amplifier circuits.

The basics of signal amplification

3060 implied HN points • 07 Feb 23
  1. Amplification circuits are essential for adjusting weak signals for use in electronic devices like speakers and LEDs.
  2. Operational amplifiers are integrated circuits that simplify amplification tasks by maintaining high input impedance and providing good current output capabilities.
  3. Consider frequency and noise considerations when designing amplification circuits to ensure they perform effectively and minimize interference.

Designing your own PCBs

2652 implied HN points • 09 Mar 23
🕹 Technology Electronics Manufacturing Tools Prototyping
  1. Designing your own PCB allows for faster iteration on new designs compared to ordering custom circuit boards.
  2. KiCad is a recommended tool for designing hobby PCBs due to its extensive library of footprints and open-source nature.
  3. Consider important factors like component placement, trace widths, and manufacturing constraints for successful PCB layout.

MCU land, part 10: blocks all the way down

1224 implied HN points • 20 Sep 23
🕹 Technology Graphics Audio
  1. Using a 32-bit MCU was necessary for storing graphics assets like bitmaps and ensured smooth gameplay.
  2. The display quality is not just about resolution; advancements in technology like camera sensors and display panels also play a crucial role.
  3. Game development on microcontrollers involves considerations like random number generation, handling rapid player inputs, and optimizing rotations for a smooth gameplay experience.

Square waves, or non-elephant biology

2040 implied HN points • 18 Apr 23
🔬 Science Physics Engineering Mathematics Technology
  1. Analyzing electronic circuits with square wave signals is more complex than with sine waves.
  2. Square waves can be approximated as a sum of sine waves at the fundamental frequency and odd multiples.
  3. Understanding the behavior of square waves and their harmonics is essential for circuit design and noise suppression.

The miracle of ChatGPT

2652 implied HN points • 03 Dec 22
  1. ChatGPT is a cutting-edge language model that can answer factual questions and perform creative tasks.
  2. ChatGPT relies on statistical predictions and may struggle with topics not extensively discussed online.
  3. ChatGPT's answers may sound authoritative, but can lack substance, blurring the line between useful knowledge and linguistic tricks.

On effective altruism

1836 implied HN points • 19 Nov 22
  1. Effective altruism focuses on donating to charities that make the best use of funds.
  2. Cause prioritization in effective altruism aims to maximize global impact per dollar spent.
  3. Local giving can have a significant impact and does not rely on global scale measurements.

Hell is other people: performance management at Big Tech

282 HN points • 29 Jan 24
💼 Business Tech Companies Performance Management Promotions Corporate culture
  1. Performance management at Big Tech companies can cause anxiety and stress among employees due to the focus on fairness and comparison with peers.
  2. Tech companies like Google have introduced peer-based performance evaluations to enhance fairness and transparency.
  3. Despite efforts to create more egalitarian performance management processes, the actual outcomes often involve bland feedback and reliance on managers for decisions.

A neophyte's introduction to video

1020 implied HN points • 06 Dec 22
  1. Videos add a new dimension - time - and require different techniques like frequent cuts for good pacing and spatial continuity.
  2. For filming, consider short takes with a tripod for DIY projects, and longer takes with a wide-angle lens for family videos.
  3. Editing involves choosing soundtracks, using transitions synced to beats, mixing audio, color correction, and rendering high-quality backups.

What's in an op-amp?

816 implied HN points • 11 Feb 23
  1. An operational amplifier typically consists of a differential input stage, a voltage amplifier, and a push-pull output circuit.
  2. The behavior of a field effect transistor (FET) in amplification is distinct from that of a typical resistor due to its strong dependence on input signals and voltages.
  3. To improve op-amp circuits, components like FETs and current mirrors can be used to create a wide range of voltage drops and maintain a steady flow of current, enhancing performance.

MCU land, part 8: DMA bit-vending machines

612 implied HN points • 03 Mar 23
🕹 Technology Microcontrollers
  1. DMA controllers on microcontrollers like Cortex-M7 allow for memory transfers without CPU involvement.
  2. Building a "bit-vending machine" with DMA can streamline communication protocols for displays or other devices.
  3. Using DMA with hardware sync signals like PIODCCLK or PWM can enable precise, fast data transfers in digital circuits.

Not so fast, Mr. Fourier!

119 HN points • 12 Mar 24
🔬 Science Computing Signal Processing Mathematics Algorithms Engineering
  1. The discrete Fourier transform (DFT) is a crucial algorithm in modern computing, used for tasks like communication, image and audio processing, and data compression.
  2. DFT transforms time-domain waveforms into frequency domain readings, allowing for analysis and manipulation of signals like isolating instruments or applying effects like Auto-Tune in music.
  3. Fast Fourier Transform (FFT) optimizes DFT by reducing the number of necessary calculations, making it more efficient for large-scale applications in computing.

Now you're thinking with relays

209 HN points • 01 Nov 23
🕹 Technology Hardware Circuits Microcontrollers
  1. Building a one-bit computer with an ALU is possible and can simplify circuitry.
  2. Relays are well-suited for building digital logic due to their binary operation and signal amplification.
  3. Implementing arithmetic operations like addition, subtraction, multiplication, and division using relays is feasible but requires thoughtful circuit design.

Signal reflections in electronic circuits

185 HN points • 25 Nov 23
🕹 Technology Electronics Circuits
  1. Signal reflections in electronic circuits can cause echoes of previously-transmitted signals due to impedance discontinuities.
  2. Electronic signals do not propagate through wires instantly, but travel at high speeds, around 80% of the speed of light in vacuum.
  3. Matching the characteristic impedance of the transmission line to the transmitter helps avoid issues with signal reflections in high-speed digital electronics.

The asymmetry of nudges

103 HN points • 24 Feb 24
🕹 Technology Big Tech API Browser Extensions Privacy
  1. It's common to blame big businesses for unethical practices, but often founders and CEOs are genuinely trying to do the right thing.
  2. The development of Manifest V3 in Google Chrome, though controversial, aimed to address major security and privacy risks posed by browser extensions.
  3. The concept of the asymmetry of nudges highlights how well-intentioned changes in tech companies can inadvertently limit user choices or negatively impact user experience.

The evolution of expert communities

125 HN points • 12 Nov 23
🎭️ Culture Online Communities Expertise Community Dynamics
  1. Online expert communities follow a general lifecycle model with stages of orderly growth, deluge, crackdowns, meme slope, and terminal plateau.
  2. Uncontrolled growth of online communities can lead to issues like repetitive questions, declining discussion quality, and the need for elaborate rules.
  3. As online expert communities evolve, they might face challenges like elitism, loss of meaningful discussions, and a shift towards off-topic topics.

A reactionary take on memory safety

42 HN points • 01 Mar 24
🕹 Technology Security Programming Government Software Coding
  1. Memory safety in programming languages like C and C++ is a significant issue due to the risk of buffer overflows and other coding errors.
  2. Although there is a push to adopt memory-safe languages like a mandate from The White House, the practicality and necessity of such a move is questionable.
  3. Challenges in enforcing a complete shift to memory-safe languages include the limited exposure of critical code to attacks and the fact that other security vulnerabilities are more common in causing breaches.

How do transistors work, anyway?

175 HN points • 29 Nov 22
  1. Understanding transistors is essential for grasping electronics' impact on our daily lives.
  2. Conduction in solid-state electronics hinges on electron flow and pressure equalization.
  3. Different types of transistors like JFETs, MOSFETs, and BJTs have unique characteristics and functions.

Writing at work

80 HN points • 02 Dec 22
  1. Recognize the importance of proofreading and reading text out loud for clarity.
  2. Craft a clear tagline for your writing and focus on key points to convey.
  3. Tailor your writing to your audience, prioritize clarity over complexity, and simplify sentences for better engagement.

Afternoon project: JPEG DCT text lossifizer

3 HN points • 17 Mar 24
🕹 Technology Algorithms Compression Text Analysis
  1. Using discrete cosine transform (DCT) for lossy compression can be applied to text data by converting it into frequency coefficients, quantizing them, and then reversing the process to obtain reduced-fidelity text.
  2. Mapping text data to numerical representation through a perceptual character table, rather than ASCII, can significantly improve readability even in high quantization settings.
  3. In text compression, focusing on higher-frequency components is crucial for maintaining readability, unlike image compression where higher-frequency components are reduced more aggressively.

Product security: barking up the wrong tree

2 HN points • 13 Mar 24
🕹 Technology Security Software Enterprise Coding Vulnerability
  1. The focus on product security often overshadows the more critical aspect of enterprise security.
  2. Enterprise security faces challenges like employee actions that can bypass security measures, demonstrating the need for a paradigm shift.
  3. Successful security programs accept the inevitability of compromise and prioritize detection, response, and containment over aiming for perfect defenses.

A brief history of counting machines

3 HN points • 26 Aug 23
💾 History Technology Trade Invention Development Evolution
  1. The history of counting machines dates back thousands of years, with early tools like abacus and multiplication tables.
  2. Slide rules were a significant invention in the 17th century, simplifying multiplication and division through logarithms.
  3. The evolution of calculators saw advancements like carry mechanisms and the separation of input and accumulator registers, paving the way for modern electronic calculators.