Forrest M Mims Circuit Scrapbook

A Proper Guide to Forrest M Mims Circuit Scrapbook and Why It Still Deserves Your Shelf Space

Most people buy the Mims scrapbook because they saw a reference on a forum and assumed it was some vintage novelty. It isn't. The three volumes — Engineers Notebooks, Circuit Scrapbooks, and the later Electrical Engineering notebook — are genuinely practical references, but only if you know how to use them properly. I've gone through them cover to cover more times than I'd like to count, usually when I'm stuck on a project and a proper datasheet isn't cutting it. Forrest M. Mims III spent decades writing for Electronic Servicing & Technology magazine, and his Circuit Scrapbook column was essentially a grab bag of circuits — oscillators, sensors, timing circuits, driver stages, power supplies — arranged by function. He didn't write the way most textbook authors do. There's no chapter intro about why MOSFETs matter or a paragraph about the history of op-amps. He just shows you the circuit, gives you the component values, and moves on. That's the whole method. You flip to the section you need, find a circuit that's close to what you're after, modify the values, and go from there. The first volume, commonly referred to in searches as the Forrest M Mims Circuit Scrapbook, is organized around discrete and IC-based building blocks. You'll find circuits for 555 timers, comparator applications, basic amplifiers, sensor interfaces, and logic gates. The second volume covers more advanced topics like microcontroller projects, interface circuits, and some higher-frequency designs. The third volume, the Electrical Engineering Notebook, is where things get genuinely useful for anyone working in the field — it includes transistor characteristics, IC pinouts, and a bunch of quick-reference calculations that Mims himself apparently used on the job.

How to Actually Use These Books Without Wasting Your Time

The biggest mistake people make is treating the scrapbook like a catalog. They flip through, see a circuit that looks interesting, try to build it exactly as drawn, and then wonder why it doesn't work right. Mims designed these circuits with real-world tolerances in mind, but the schematics are minimalist by design. He often leaves out decoupling capacitor values, doesn't always specify the exact resistor tolerance required, and sometimes assumes you'll figure out the biasing yourself. Here's the practical workflow that actually works: identify the function you need first, not the circuit. If you need a pulse generator, go straight to the oscillator section. Scan for a topology that matches your frequency range and power constraints. Then look at the surrounding text — Mims usually includes a short paragraph explaining how the circuit works and what each component does. Read that. It's dense but useful. After that, calculate the component values for your specific application rather than blindly copying his numbers. Mims' examples typically run on 5 to 15 volts and use standard 5% resistor values, which is fine for a demonstration circuit but might not suit your actual project. I spent two hours debugging a Mims IR remote receiver circuit last year because I didn't check the supply current spec on the phototransistor he referenced. The original circuit assumed a TSOP1738-style receiver with built-in filtering, but the generic part number he listed could've been any number of bare photodiodes. I swapped it for a proper TSOP and it worked immediately. The schematic itself wasn't wrong — the component assumption was the gap.

What Beginners Miss About These Circuits

The first thing people don't understand is that Mims' circuits are meant to be starting points, not finished products. He wrote them for hobbyists and service technicians, not for production design. That means a lot of the schematics will work on a breadboard but fall apart when you move to a PCB unless you add proper decoupling and account for parasitic capacitance. Another thing that trips people up: the component value tables in the back of the books. These are actual reference data — transistor gain ranges, op-amp offsets, IC specifications — compiled from real datasheets. A lot of people skip right past them. They're worth sitting down and actually reading through at least once. The table for 2N-series transistor gain bands, for example, is something I reference more often than any generic online chart because Mims included actual spread data from multiple manufacturers, not just a single nominal hFE value. There's also a nuance with the oscillator circuits that isn't obvious unless you build them. Mims often uses simple RC timing networks for oscillator frequency determination. On paper these look stable. In practice, the frequency drifts with temperature and supply voltage. If you're building something where timing accuracy matters — a tone generator, a metronome circuit, anything clock-related — you need to add a voltage regulator and consider a crystal or ceramic resonator instead of a plain RC network. The book doesn't always make this distinction clear, but it's implied if you understand the underlying theory.

Download and Where to Find Them

The official publications are still in print through various electronics hobby suppliers. The circuit scrapbook volumes are available from Amazon, eBay, and specialty booksellers. There are also digitized versions floating around the internet — PDF scans of the earlier editions circulate on forums and archive sites. I can't link to any of those directly since I don't verify their legality, and honestly the print versions are cheap enough that scanning them yourself might be more efficient if you need to search the text. If you go the digital route, the quality varies. Some scans are crisp enough to read the small print. Others are blurry and hard to interpret. The best approach is to get the physical book and keep it on your workbench. That's what I did, and now I have three volumes stacked next to my soldering station.

When the Scrapbook Doesn't Help

Let me be blunt about the limitations. These books were written starting in the 1970s and continued through the 1990s. The technology coverage reflects that era. If you're working with modern microcontrollers, high-speed digital circuits, or anything that requires EMC compliance, Mims isn't going to cover it. The op-amp circuits use older 741 and 390 series parts that are functionally obsolete. The transistor circuits reference parts like the 2N2222 and 2N3904 primarily, which are still fine for low-power work but won't help you design a switch-mode power supply. Also, the books don't include simulation models. If you're someone who likes to simulate circuits before building them — and you should be doing that for anything beyond a simple LED blinker — you're out of luck. Mims never published SPICE models for his circuits. There are community efforts to model some of them, but they're inconsistent at best. For modern design work, pair the scrapbook with a contemporary reference like Horowitz and Hill's The Art of Electronics. The scrapbook gives you a huge library of proven topologies and practical circuit intuition. Horowitz and Hill gives you the theory and the modern design constraints. Use both. Rely on either one alone and you'll hit gaps.

Getting the Most Out of the Forrest M Mims Circuit Scrapbook

The books reward patience. The circuits are simple, which is intentional. Mims stripped away everything non-essential so you could see how the topology actually works. That's why they're still useful thirty years later. A lot of modern textbooks bury the fundamental concepts under simulation screenshots and software workflows. Mims makes you build it, measure it, and understand it. My personal workflow with these books is to keep a notebook of circuits I've built and tested. When I encounter a new problem, I flip to the relevant section, find something close, and adapt it. The adaptation is where the learning happens. Just copying a circuit from the book without understanding why it works the way it does is about as useful as a paperweight. One final note: the circuit naming convention can be confusing if you're not used to it. Mims often refers to circuits by their function — "Astable Multivibrator," "One-Shot Timer," "Schmitt Trigger Inverter" — rather than by part number. This is actually helpful once you get used to it because it means you can find a circuit type without knowing the exact IC or transistor. But it also means you might encounter the same topology under different names in different sections. Don't assume two differently named circuits are fundamentally different just because the title varies. Sometimes they're the same circuit with slightly different biasing.