Microcontrollers

Just a curiosity question if I may. What brand of flux you are using to hand solider parts to PCB?

I'm having trouble with the following attach circuit, it keeps blowing the LED in the optocoupler.  So what is wrong with my design? The incoming signal is a 12V pules (1K to 100KHz), I need the zener to clamp the wave to a 5V     

Greetings,I am a researcher currently developing a study on the measurement of difficulty/complexity in electronic circuits. I am looking for books, scientific articles, instructional materials, or datasets that present sets of electronic circuits accompanied by some indication of difficulty, complexity level, or pedagogical classification, even if such indication is subjective or approximate.Any reference would be welcome, including classic textbooks, lecture notes, datasets, academic repositories, or materials used in technical or university-level education. If you are aware of works that organize circuits by difficulty level, or that could be used as a basis for comparative analysis, I would greatly appreciate your help and recommendations.On my ResearchGate profile, I have published some works on complexity measurement in other domains, such as industrial property patents and C programming language source code, which may help contextualize my research approach.Thank you in advance for any help or references you may be able to share.

Starting a perfect for someone. He wants to detect a TRIGGER and GATE signal (to control a solid state relay). . He says the TRIGGER is a pulse signal and does not know the peak voltage and does not know what the pulse wave form is. The gate accord to him is a square wave pulse that either logic 0 or 1. Pulse length can be serval seconds to minutes long.  Again, he not tells what the max voltage is.  Can someone tell me what this Eurorack CV wave formate is. Thank you. :)

Happy new year every one. I am hunting for a 30VA (PRI 120VAC SEC 12VAC) step down transformer for a project. Using a full bridge, recfire to turn the 12VAC to a 12VDC to power the circuitry, which needs at lest 2.5Amps.  Does anyone know of such animal?. 

Passivation in lithium batteries with liquid cathodes (like Li-SOCl₂, and Li-SO₂Cl₂) forms a protective lithium chloride (LiCl) layer on the anode, preventing internal short circuits and enabling long shelf life. However, this insulating layer increases internal resistance, causing a startup voltage delay that will worsen over time with storage. Using Otii Ace Pro 257-3555 and Otii Battery Toolbox developers can measure the effects of the battery passivation and better predict the battery life of their products.

A supercapacitor is an energy storage device that stores charge electrostatically, allowing for rapid charge and discharge cycles with high power density. Unlike batteries, supercapacitors have low energy density but extremely low internal resistance (ESR), making them ideal for handling short, high-current pulses and stabilizing voltage during load transients. In hybrid power architectures, supercapacitors are often used in parallel with primary cells (e.g., Li-SOCl₂) to absorb peak loads and minimize voltage drops. #OtiiAcePro 257-3555 with a 4-wire measurement setup, you can analyze supercapacitor behavior, tracking the storage efficiency and performance over deep voltage drops and repeated pulses.

Battery aging is the gradual deterioration of a battery’s capacity and performance over time due to chemical and physical changes within the cell. It results in reduced energy storage, higher internal resistance, and shorter operational life, and is influenced by factors like temperature, charge cycles, state of charge, and storage conditions.  Otii Ace 257-3555 /Arc Pro 256-4687 and Otii Battery Toolbox offers battery cycling to test aging and features a fully customizable test sequence, unlimited test cycles, multi-battery support, and a clean, intuitive user interface.

Hi everyone, I recently read a comparison article titled “ESP32 vs STM32 vs RP2040 vs Arduino Guide” , and I’m considering writing my own version of a comparison post focusing on these microcontrollers. The article gave me a good overview, but I’d like to bring in additional perspectives — especially from engineers and hobbyists here — to make the comparison more complete, practical, and nuanced. Before I start writing, I wanted to ask the community: What aspects do you think are most important when comparing microcontrollers like ESP32, STM32, RP2040 and Arduino — e.g. performance, power consumption, development ecosystem, community support, ease-of-use, peripheral support, cost, etc. Based on your own experience, which MCU(s) do you prefer for small-scale embedded projects, and why? Are there any pitfalls, trade-offs or “hidden gotchas” when choosing among them that a newcomer might ignore? What format or content would you find useful — for example: benchmark comparisons; code examples; power/performance tests; cost vs performance analysis; community-support summary; or application-based advice (IoT, battery-powered devices, robotics, etc.) My goal is to combine objective data (specs, benchmarks) with real-world usage feedback, to help others (especially less experienced engineers / makers) choose the most suitable MCU for their needs. If you have time and interest, I’d greatly appreciate your input — opinions, stories, suggestions, even criticisms. Thanks in advance!

Battery discharge profiles describe how a battery’s voltage changes over time (or over capacity) as it discharges under a load. They're crucial for understanding battery performance, and they are typically presented in battery data sheets as a plot of Voltage (y-axis) vs. Time or Capacity (x-axis). The load is also typically assumed to be constant. Pulsed loads better reflect the real-world conditions batteries face in sensor and IoT devices. If you are discharging batteries with Otii Arc 256-4687 and Ace Pro 257-3555 and Otii Battery Toolbox your battery discharge profiles for pulsed loads will include internal resistance information and can therefore be used to emulate battery behaviour.

State of Charge (SoC) is the ratio of the current charge in a battery to its maximum charge capacity, expressed as a percentage (SoC = (current capacity / maximum capacity) × 100%). Accurate SoC estimation, based on techniques like open-circuit voltage measurement, coulomb counting, or model-based algorithms, is critical for battery management systems (BMS) to optimize performance, ensure safety, and extend battery lifespan.  Using Otii Ace 257-3555 /Arc Pro 256-4687 and Otii Battery Toolbox you can emulate batteries for different SoC for your embedded device and specific use case.

Internal resistance is the opposition to current flow within a battery, caused by its materials, chemical processes, and structure. It leads to voltage drops and heat generation under load, and typically increases with battery aging, temperature changes, and usage, affecting overall performance and efficiency.If you are discharging batteries with Otii Arc 256-4687 and Ace Pro 257-3555 and Otii Battery Toolbox your battery discharge profiles for pulsed loads will include internal resistance information and can therefore be used to emulate battery behaviour.

When measuring currents and voltage with thin, long cables the resistance in the cables and connectors might cause errors in the voltage measurement. In a 2-wire setup, current and voltage share the same path and resistance can affect the accuracy. A 4-wire setup uses separate wires between power and voltage sensing, thus avoiding the added error that the cables and connectors introduce. 4-wire measurements can be used in any set-up with Otii Arc 256-4687 and Ace Pro 257-3555.

Low-power measurements aren't about how small a value you can detect — they’re about how accurately you can measure those small values. Accuracy is specified as ±(gain error + offset error), or ±(X% + Y), where X is the percentage error and Y is the offset error. This means your measurement includes both a fixed offset error of Y and a scaling error of X percent. Example: the current measurement accuracy for the main channel of the Otii Ace 257-3555 when measuring low currents is ±(0.05% + 25nA). So if you measure 1 µA, the expected error would be a maximum of 0.0255 µA.

In-line (Ampere Mode) power measurement the measurement device is connected in series with device under test, measuring the current flow through the system. Named after "ampere meter" since it primarily focuses on current measurement. Most instruments provide either full power mode measurements or only ampere mode measurements. Otii Ace Pro 257-3555 provides both options. Furthermore, to measure additional voltage, power, and energy, the ampere mode setup can be extended with a 4-wire connection using SENSE pins in the expansion ports of the Ace.