About This Site

Barry's VHF Radio and Coilguns

I like to drive up hilltops to activate Maidenhead grid squares on 6 meters. Here are a bunch of places I know about.

In 2020, I designed and built a dashboard device with an Arduino and GPS to help navigate. It's called Griduino™.

A quote from the ARRL Contest Update, Feb 18, 2021:
Barry, K7BWH, sought to solve the problem of known how far it was to the next grid during mobile operations, so he did something about it. The result is the Griduino, the combination of GPS, barometer, real-time clock, code generator, audio chain, and a bright display. It has an audible announcement as you cross into a new grid square, and for microwave ops it optionally announces every 6-digit grid line. It sure beats watching a GPS or tablet while driving. You can find construction details on Github/barry-ha, or join in on the email discussion.


Learn about coilgun design theory, design and implementation. We have several low-power coilguns, maglev systems and other projects. This website is my engineering notebook.

Barry Hansen Read the slides for Magnetic Launches - Hands-on Ideas 10, my presentation about coilguns on May 22, 2013.

This is a quick way to see how and why it started, what happened, and where it's going.

Download the presentation here.

As of 2017-02-15 this website supports SSL. Let me know if you spot anything broken or just plain strange.

Click here to see the latest coilgun, my best coilgun or my levitator.
Also try out my RLC Simulator and Inductor Simulator.

coil gun with one coil What is a coilgun or gauss gun? It accelerates a piece of iron or steel down a tube. The tube runs through a series of electromagnetic coils (like solenoids). There are no sparks or noise or impressive side effects (or parts to wear out). Some careful timing circuits energize each coil in sequence. The principle of magnetic attraction draws the projectile along at rapidly increasing speed.

Why build a coilgun? It demonstrates many basic concepts of magnetic machines. A coilgun is foremost an example of a solenoid. These appear practically everywhere, from car door locks to doorbells, from diskette drive ejectors to fuel injectors. The only difference is that most solenoids limit the range of travel, and usually have a spring return. A coilgun is also an example of a simple linear motor.

A coilgun is scalable to very large applications, possibly as large as a mass driver to put payloads into orbit. It's a keen space-age toy. It has no moving parts -- there's the magic of invisible forces at work. It requires no special construction techniques or unusual tools. Winding coils is fun and relaxing (at least for the first few!). Even small coils are remarkably powerful.

You can also learn about magnetic levitation. These pages include complete design details for several maglev demonstrators which levitate small iron parts. Read all about it and see levitation pictures.

Mark 2 Coilgun Mark 2 Coilgun

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