Lost Secrets of the H-Bridge, Part I: Ripple Current in Inductive Loads
Jason Sachs digs into what PWM switching actually does to current in an H-bridge with an inductive load, and why that ripple matters for motors and power converters. He derives closed-form ripple formulas, shows how to compute a reference current I_R0 = VDC·T/L, and uses Python and sympy to plot and verify results. Read it for practical rules to halve ripple and raise its frequency.
Adventures in Signal Processing with Python
Jason Sachs shows how PyLab (numpy, scipy, matplotlib) can handle many signal-processing and visualization tasks engineers usually reach for MATLAB to do. He walks through practical examples including PWM ripple, two pole RC filters, and symbolic math with SymPy, and shares real-world installation tips and trade-offs. The post closes with pointers to IPython and pandas to speed interactive analysis and data handling.
Implementation Complexity, Part II: Catastrophe, Dear Liza, and the M Word
Complex systems hide risks that often surface long after the developers move on, and maintenance usually becomes the true costliest burden. Jason Sachs walks through catastrophic engineering failures, cyclic dependencies, proprietary lock-in, supply-chain fragility, redundancy pitfalls, and software traps like state-machine bugs. The post closes with practical, engineer-focused advice on designing simpler, more maintainable embedded systems and planning for lifecycle safety and repair.
Implementation Complexity, Part I: The Tower of Babel, Gremlins, and The Mythical Man-Month
Jason Sachs argues that implementation complexity often outpaces manpower and good intentions, using the Tower of Babel and Fred Brooks's The Mythical Man-Month as lenses. He walks through communication costs, Kolmogorov complexity, and interface pitfalls with concrete examples like the NEMA 5-15 outlet, then offers pragmatic approaches such as modular design, gray-box awareness, and documenting assumptions to spot the gremlins before they derail a project.
Isolated Sigma-Delta Modulators, Rah Rah Rah!
Analog isolation can blow up DAQ budgets, but isolated sigma-delta modulators let you send a single 1-bit stream and a clock across the barrier, keeping costs down. Jason walks through Avago, TI, and Analog Devices parts, explains sigma-delta noise shaping in plain terms, and calls out the real engineering work: converting a 10–20 MHz bitstream into usable samples with sinc/CIC decimators or FPGA filtering.
Oscilloscope review: Hameg HMO2024
Jason Sachs tests the Hameg HMO2024, a 200MHz 4-channel mixed-signal oscilloscope that promises Agilent-like features at a lower price. He finds strong analog noise performance, useful hi-res and zoom modes, and inexpensive serial-decode options, but warns of clumsy digital-input handling, awkward data-transfer software, and missing per-channel thresholds and Ethernet waveform export. The review helps budget-conscious embedded engineers weigh the trade-offs.
How to Estimate Encoder Velocity Without Making Stupid Mistakes: Part I
Encoder velocity estimation is easy to get wrong, and Jason Sachs walks through the traps engineers fall into. He demolishes the common advice to time between encoder edges, shows how encoder quantization and state-width errors break that approach, and argues for fixed-rate sampling with sensible filtering for most control uses. Part II will cover more advanced estimators for higher performance needs.
Chebyshev Approximation and How It Can Help You Save Money, Win Friends, and Influence People
Are expensive math libraries or huge lookup tables eating CPU and flash on your microcontroller? In this practical guide Jason Sachs shows how Chebyshev polynomial approximation (with range reduction, splitting, and small interpolated tables) can give near-minimax accuracy while using far less code and runtime. The post compares Taylor series, plain and interpolated tables, and explains how to fit empirical sensor data and evaluate coefficients efficiently.
Thoughts on Starting a New Career
Changing jobs can be a reset button for your engineering momentum. Jason Sachs reflects on leaving a 16-year role to join Microchip as an applications engineer in motor drives, and he distills practical advice on early-career choices, mentorship, networking, interview tactics, and keeping skills marketable. The post also highlights workplace factors and small perks that affect productivity, giving embedded engineers actionable steps to plan a career transition.
10 Software Tools You Should Know
Embedded work gets a lot easier when you have the right software stack, and Jason Sachs lays out the tools he leans on every day. From revision control and file comparison to build systems, scripting, analysis, documentation, QA, and command-line utilities, he focuses on practical picks that save time and reduce mistakes. The list is opinionated, but it is full of the kind of workflow advice that helps engineers stay productive.
Wye Delta Tee Pi: Observations on Three-Terminal Networks
Three-terminal passive networks, wye, delta, tee, and pi, are more interchangeable than many engineers expect. Jason Sachs walks through Kennelly's wye-delta formulas, Z and Y matrix representations for tee and pi two-port networks, and worked examples ranging from balanced to highly skewed impedances. The post highlights practical payoffs, including using topology transforms to substitute hard-to-source capacitors with simpler, precision-friendly parts.
Bad Hash Functions and Other Stories: Trapped in a Cage of Irresponsibility and Garden Rakes
A tiny filename decision in MATLAB's publish() can silently swap rendered equations, and Jason Sachs shows why that matters. He reproduces the bug, walks through hash-function basics and collision math, and contrasts safe and unsafe caching strategies. The piece then broadens into practical lessons about software fringes, legacy constraints, and the usability traps that leave engineers repeatedly stumbling over avoidable design choices.
10 Software Tools You Should Know
Embedded work gets a lot easier when you have the right software stack, and Jason Sachs lays out the tools he leans on every day. From revision control and file comparison to build systems, scripting, analysis, documentation, QA, and command-line utilities, he focuses on practical picks that save time and reduce mistakes. The list is opinionated, but it is full of the kind of workflow advice that helps engineers stay productive.
Modulation Alternatives for the Software Engineer
Jason starts with a hardware curiosity, the 7497 synchronous rate multiplier, and turns it into a practical lesson for firmware engineers. He contrasts conventional PWM with a simple accumulator-based method called "synthetic division," showing how it implements first-order delta-sigma behavior in software. The post explains when to pick PWM or delta-sigma and why the accumulator trick can give higher effective resolution at low update rates.
Have You Ever Seen an Ideal Op-Amp?
Forget the ideal op-amp fantasy, Jason Sachs walks through the practical nonidealities that make textbook gain formulas fail in real circuits. Using the uA741C and TLC081C as examples, he explains offset voltage, input bias and offset currents, common-mode and supply rejection, gain-bandwidth and slew-rate limits, plus capacitive loading, RF rectification and overload recovery. Read to learn which datasheet specs matter and why.
Linear Regression with Evenly-Spaced Abscissae
Jason Sachs cuts through the matrix algebra to show a tiny trick for linear regression when x values are evenly spaced. You can compute the intercept as the mean and the slope as a simple weighted sum with arithmetic weights, using q = 12/(m^3 - m). The post includes Python examples and a compact routine to get least-squares coefficients without matrix solvers.
Implementation Complexity, Part I: The Tower of Babel, Gremlins, and The Mythical Man-Month
Jason Sachs argues that implementation complexity often outpaces manpower and good intentions, using the Tower of Babel and Fred Brooks's The Mythical Man-Month as lenses. He walks through communication costs, Kolmogorov complexity, and interface pitfalls with concrete examples like the NEMA 5-15 outlet, then offers pragmatic approaches such as modular design, gray-box awareness, and documenting assumptions to spot the gremlins before they derail a project.
Byte and Switch (Part 2)
Running a thermistor front end from a single AA cell exposes problems you might not expect. Jason Sachs walks through a switchable-gain divider using a P-channel MOSFET and shows how MOSFET off-state leakage and low supply voltages can corrupt high-impedance temperature readings. The post compares bipolar transistors and analog switch ICs as fixes and gives practical component guidance for one-cell designs.
Oscilloscope review: Hameg HMO2024
Jason Sachs tests the Hameg HMO2024, a 200MHz 4-channel mixed-signal oscilloscope that promises Agilent-like features at a lower price. He finds strong analog noise performance, useful hi-res and zoom modes, and inexpensive serial-decode options, but warns of clumsy digital-input handling, awkward data-transfer software, and missing per-channel thresholds and Ethernet waveform export. The review helps budget-conscious embedded engineers weigh the trade-offs.
Hot Fun in the Silicon: Thermal Testing with Power Semiconductors
Bringing hundreds of amps into the lab for low-Rds(on) MOSFET thermal tests is impractical. Jason Sachs demonstrates a clever workaround using a zener diode, a series resistor, and a constant-current lab supply to dump the same watts into the device at much lower current. He also explains how to use datasheet RθJC values and type T thermocouples to estimate junction temperature and size heatsinking or airflow.
Efficiency Through the Looking-Glass
Efficiency numbers can be misleading, Jason Sachs argues, because they hide the real cost engineers pay in wasted watts. This post flips the focus from percent efficiency to absolute power loss, shows how losses often stay nearly constant across loads, and walks through a practical thermal method to measure those losses more reliably than subtracting input and output power. Read it to rethink how you budget heat and energy in designs.
Implementation Complexity, Part II: Catastrophe, Dear Liza, and the M Word
Complex systems hide risks that often surface long after the developers move on, and maintenance usually becomes the true costliest burden. Jason Sachs walks through catastrophic engineering failures, cyclic dependencies, proprietary lock-in, supply-chain fragility, redundancy pitfalls, and software traps like state-machine bugs. The post closes with practical, engineer-focused advice on designing simpler, more maintainable embedded systems and planning for lifecycle safety and repair.
Shibboleths: The Perils of Voiceless Sibilant Fricatives, Idiot Lights, and Other Binary-Outcome Tests
Binary tests look simple until you try to pick a threshold, because false positives, false negatives, and base rate all collide. Jason Sachs uses a deliberately absurd detective story, then walks through the math of expected value, medical screening tradeoffs, idiot lights, and even a triage-style three-way decision. The payoff is a practical way to think about when a pass/fail signal helps, and when raw data or a second test is worth the extra complexity.
In Memoriam: Frederick P. Brooks, Jr. and The Mythical Man-Month
Fred Brooks’ The Mythical Man-Month is still a surprisingly sharp guide to software projects, and Jason Sachs shows why it matters even more than its old mainframe setting suggests. He revisits Brooks’ ideas on surgical teams, conceptual integrity, throwaway prototypes, and schedule estimation, then maps them to modern embedded and software engineering realities. The result is a tribute, a book review, and a practical reminder that roles, architecture, and testing still make or break delivery.
Turn It On Again: Modeling Power MOSFET Turn-On Dependence on Source Inductance
This is a short article explaining how to analyze part of the behavior of a power MOSFET during turn-on, and how it is influenced by the parasitic inductance at the source terminal. The brief qualitative reason that source inductance is undesirable is that it uses up voltage when current starts increasing during turn-on (remember, V = L dI/dt), voltage that would otherwise be available to turn the transistor on faster. But I want to show a quantitative approximation to understand the impact of additional source inductance, and I want to compare it to the effects of extra inductance at the gate or drain.
How to Succeed in Motor Control: Olaus Magnus, Donald Rumsfeld, and YouTube
Jason Sachs turned frustration with algorithm-heavy motor-control app notes into a practical MASTERs class, now available on YouTube. He walks through building a fifteen-minute field-oriented control refresher, the hazards teams commonly miss, and the months of prep required to make a polished technical lecture. Read for a candid behind-the-scenes look at teaching motor control to engineers and tips you can apply to your next drive project.
The Dilemma of Unwritten Requirements
Unwritten requirements quietly wreck projects, and Jason Sachs uses a humble wooden spool to illustrate how small mechanical and manufacturing choices become visible system behaviors. He contrasts craft-store spools with industrial ones to show where hidden assumptions like concentricity get dropped in the name of cost. The post urges engineers to surface externally visible trade-offs to customers or contractors and to iteratively capture discovered requirements.
Linear Feedback Shift Registers for the Uninitiated, Part IX: Decimation, Trace Parity, and Cyclotomic Cosets
Taking every jth bit of a maximal-length LFSR uncovers a surprising algebraic structure. Jason Sachs walks through cyclotomic cosets, shows why decimation by powers of two preserves minimal polynomials, and connects LFSR output to trace parity and simple bitmask parity computations. The article uses hands-on Python with libgf2, Berlekamp-Massey, and state recovery so you can reproduce and automate these analyses.
Scorchers, Part 1: Tools and Burn Rate
Small purchases often pay for themselves faster than you expect, and Jason Sachs walks through the math to prove it. He shows how to compute a fully burdened labor rate, including taxes, benefits, overhead, holidays, and productive hours, then compares that rate to the price of common tools. The practical conclusion is simple: if a sub-$100 utility saves about an hour of productive work, just buy it.
Oh Robot My Robot
Jason Sachs turns a familiar poem into a robot sendoff, and the result is equal parts funny and oddly technical. The piece riffs on broken hardware, vanishing memory, and a machine that has clearly seen better days, all while keeping the rhythm of a classic elegy. If you enjoy engineering humor with a literary twist, this is a quick, memorable read.
