Do It Yourself

Apparent Diurnal Variation in Background Radiation

Between 1998 and 2001 I measured background radiation in Fourmilab's computer lab with a Geiger-Müller tube interfaced to a computer. Analysing the data revealed both an apparent divergence from a Gaussian distribution of counts per minute and a variation in background radiation with time of day. This page presents the data, analysis, speculation on possible causes, and provides a link whence you can download the data and programs for your own investigations.

Fourmilab's Coruscating, Actinic, (partially) Nuclear-Powered Christmas Lights

There are few things as frustrating as putting up your Christmas lights and discovering that a majority of the series strings of incandescent bulbs have failed. Why not put an end to it forever by replacing them with Light Emitting Diodes (LEDs)? This do-it-yourself project migrates from existing incandescent lights to LEDs according to your own schedule and budget.

How to Play DVDs with any Region Code on Windows 98

Digital Video Discs (DVDs) bear a “region code” intended to block their being viewed on players sold in a different geographical area. Customers in Europe, for example, who order DVDs from online vendors in North America may receive discs their players won't accept. Many computer-based DVD decoders are not hardware region locked and are physically capable of playing discs from any region. Microsoft, however, have blocked this in the DVD Player shipped with Windows 98 by a crude software kludge. This document explains how to circumvent the region lock and play any DVD on Windows 98. These instructions apply only to the Microsoft DVD Player included with Windows 98, not other players supplied with decoder boards, and will not work if your DVD decoder card contains a hardware region lock. See the full document for additional details.

Bending Spacetime in the Basement

This “basement science” experiment demonstrates the universality of gravitation, showing the gravitational attraction between masses of less than a kilogram. Could Archimedes have discovered universal gravitation nineteen centuries before Newton? Well, let's see….


Illustrated, can't fail, easy-to-make delicious meals with all natural ingredients and minimal time and work to prepare at home.


Quantum mechanics teaches us that, at the deepest level, uncertainty rules the universe: there are things we cannot predict, even in principle. HotBits harnesses this fundamental uncertainty of nature to generate truly random bits, unlike the pseudorandom sequences created by an algorithm on a computer. Along the way, you'll find a discussion of the hardware and software used to generate the random bytes comprehensive enough to build your own, and peek under the hood of quantum mechanics to see why the data are genuinely random, and some of the implications of all this.

Mind Grenade

In the fall of 1969, I made my first foray into digital electronics by designing and building my own version of a random music generator invented by Harry S. Pyle. Fifty years later, it still works. Explore digital design from half a century ago, how this device which looked and sounded like people thought computers ought to worked, and enjoy a modern software emulation that runs inside your Web browser.

Nixie Tube Clock

In the bronze age of computing and electronics test equipment, nixie tubes were commonly used for decimal digital displays. This clock, available both in kit form and assembled, combines that vintage technology with digital electronics for a retro look and modern practicality.

Pitch Drop

The longest continuously-running scientific experiment demonstrates that even extremely viscous fluids will eventually flow as the liquids they are. Do it yourself instructions are included.

Fun with Radiation

Explorations of radiation around the house and in the air with a Geiger counter.

How to Mount a Lens on a Linhof Technika Recessed Lensboard

All right, I'll admit it: this document is a little specialised. A recessed lensboard allows a large format camera to use short focal length lenses which would otherwise not be able to focus at infinity due to the minimum extension of the bellows. The Linhof Technika recessed lensboard is supplied with a mechanism to permit a cable release to operate the shutter, whose own cable socket is buried within the recess, but with no instructions on how to install it. This document walks you step by step through the installation of a Schneider Super Angulon 47mm lens on the recessed lensboard, and explains how the curious collection of parts supplied with the lensboard are assembled to operate the shutter.

Reversing Myopia

Having been nearsighted and requiring strong optical correction all my life, I became accustomed ever since childhood to each eye exam calling for ever stronger glasses. I'd heard that the rate of change could be expected to decrease with age, but never that the trend could be reversed. Then, in 2000, I got separate reading and driving glasses, and found myself wearing the reading glasses almost all the time. Eight years later, it was obvious to me that the correction of both were too strong, and when I had my next eye exam in 2010, it showed the correction for both eyes was a full dioptre less. This document recounts my anecdotal experience and what it may mean for other nearsighted people.

Strangelove Slide Rule: Nuclear Bomb Effects Computer

Relive the chilling calculations of the Cold War with this interactive edition of the Nuclear Bomb Effects Computer published in 1962 by the United States Atomic Energy Commission. Enter the yield and range, and the full suite of weapons effects will be displayed just as on the original pocket slide rule. Nuclear weapons users who prefer a physical slide rule, either out of nostalgia or an appreciation for its ability to operate in post-apocalyptic conditions, will find instructions for making their own.

SubMarie's: Reverse-Engineering Blue Cheese Salad Dressing

Ever since I moved from California to Switzerland in 1991, people occasionally ask, “Is there anything you miss?” Well, there is the salad dressing! One of my favourite culinary concoctions in California was Marie's® Blue Cheese salad dressing. It is now available throughout the U.S., but not in Europe, and I have found no vaguely comparable product on the market here. So, it's time to roll up our sleeves and engage in a little high-fat, high-calorie, thick and creamy reverse engineering! This document starts with the list of ingredients in the original and iteratively develops a simple to prepare substitute which I find perfectly satisfactory. Readers with well-calibrated palates and access to the commercial goop for comparison taste-testing are invited to further tweak this Open Sauce recipe and share their discoveries. New September 2007 update presents results from comparison tasting with the Real Thing and provides two new recipes which attempt to converge upon the flavour of the original.

How to Replace the Fluorescent Starter in a Bug Zapper

Many a bug zapper is junked when its ultraviolet fluorescent tube fails to light or starts blinking incessantly. Replacement tubes are available, but frequently changing the tube doesn't fix the problem, which is usually due to failure of the fluorescent starter inside the device. This document explains how to replace the starter with the “guts” of a regular plug-in starter. While the example is based upon a bug zapper made by Windhager of Austria, folks who have any business poking around inside a bug zapper in the first place can doubtless generalise to other devices. Please read the warning at the top of this document before proceeding.