About This Site

What's New

May 22, 2013 - Added the Overview page for a quick introduction to how it started, what happened and where it's going. Check out the notes on each slide; very entertaining.

Sept 29, 2012 - I'm going to show a few ads on a trial basis, starting here in the nav bar. Let me know what you think.

Sept 26, 2012 - Created Oregon rover location maps, a submissions form, and generally rewrote all my rover information. This is a major code update so please report any bugs you find, thanks.

May 22, 2012 - Created a map overlay for the grid square navigation page about rovers and hilltopping.

March 30, 2012 - Added Convert Auto to my links page. Convert Auto is a great way to convert just about anything automatically. Area, angles, energy, force, power, pressure, speed, it's all in there. This is the caffiene-fueled brainchild of Lily Hammond, engineering student at NCSU.

Jan 18, 2012 - I applied a 24-hour blackout to the top pages of this coilgun website to help raise awareness of SOPA and PIPA legislation, and to ask citizens to contact their U.S. congressmen. The proposals attempt to address the growing problem of foreign websites posting copyrighted content of Big Media without permission. But the bills are fatally flawed: they create a powerful censorship tool with a technically unworkable definition of "foreign" and "domestic", a broad and vague definition of "just cause", and it breaks DNS lookup by introducing major security holes. Congress is even more tech-illerate than the media companies.

Jan 17, 2012 - Updated the Rare Washington Counties page about ham radio licenses and how they are distributed around the state. My previous figures were from 1999 and this data from the FCC database brings it current as of January 2012.

Jan 13, 2012 - Added FT-897d Settings to record a boatload of my personal adjustments. If the radio is accidentally reset to factory settings then I can easily restore my favorites.

10/14/2011 - Added link to the software competition of U.S. Imagine Cup 2012 in which the finals will be held in Seattle in April 2012.

8/23/2011 - Added maidenhead grid square map of the USA and Washington state grid squares.

6/7/2011 - Portable Coilgun Chapter 1 of '15 Dangerously Mad Projects for the Evil Genius' of the dangerously mad Simon Monk. Download it. Build it. Best write-up ever!

4/28/2011 - Fixed the "speed of sound" value to the Wikipedia value of 343.2 m/s on the Measuring Speed page.

2/23/2011 - I updated my ham radio projects pages, and added a photo tour inside my Kenwood TS-850s HF transceiver. The poor thing had something break off inside the headphone jack. See what happens when the Irretrievable Object meets the Unstoppable Screwdriver.

12/5/2010 - Coilgun cart for Mark 5 I got a cart and portable workbench for the Mark 5 coilgun. Here's the story about how I got this for free and adapted it for my coilguns.

8/28/2010 - I'm on the air again! My station is working great now that I've setup my Kenwood TS-850s at home and my Kenwood DM-710a vhf/uhf in my car. I wrote this web page about my ham radio station K7BWH (previously WA7KVC).

1/22/2010 - Added a whole new levitator chapter republished from Popular Electronics May 1996 by permission of the author, James Cicon.

12/20/2009 - Are you replacing your CRT with an LCD monitor? Here's how to convert CRT sizes into LCD widescreen dimensions. Bottom line: The monitor industry is still full of devious scumbags.

11/28/2009 - Installed 64-bit Windows-7 Professional. I like it. Be sure to check the upgrade grid to see if you need to do a clean install or not. For example, you cannot directly upgrade from any 32-bit Windows to 64-bit Windows-7.

8/2/2009 - Added a page about the Mark 5 control panel construction. It's not complete yet but these photos give you a good idea how it will eventually turn out.

Capacitor bank 7/29/2009 - Added a page about how the Mark 5 capacitor bank is mounted onto heavy copper bus bars. My "bars" came from old 3/4-inch copper pipe from some ancient antideluvian plumbing project. See how the capacitor bank is mounted to minimize bar length, resistance, inductance and total number of connections.

4/28/2009 - Bought a six-stage university project coilgun with optical sensors. This will be my next project after my big Mark 5 coilgun is built and tested. I wish I could work full time on coilguns.

2/26/2009 - Added entire chapter on AC Linear Induction Motor coilguns, written by EF Northrup in 1937.

Wedge contactor 1/25/2009 - Initial assembly of the 6KJ Mark 5 Coilgun is coming along. The copper wedge contactor is ready for bounce/settling tests and the capacitor bank is reformed and ready for busbars. There's a long way to go yet, but it seemed interesting to share the design direction with you. You can watch my progress if you follow @barryha on Twitter.

12/24/2008 - Merry Christmas everyone! I hope you all find fat juicy kilojoule capacitors under the tree, or even a new DSO storage scope! I'm working with solenoids to control a high-power contactor as the basis of my next coilgun. Nothing to show yet but stay tuned. Meanwhile I've added my Twitter feed to the home page -- click the link and follow @barryha on Twitter. Merry Christmas

12/15/2008 - I've been tinkering with copper printed circuit boards to simplify construction. Tom Gootee has some nice notes about photo transfer from a laser printer. This works well! His pages are very hard to follow, so I've reorganized and improved his work. I hope.

Discovery Channel coilgun 8/12/2008 - This mad scientist will be on TV this month! Look for:

Discovery Project Earth
"Engineering the Future"

August 22 at 9pm on channel 8 in Seattle
"Professor Roger Angel at the University of Arizona believes that placing trillions of lenses in space can diffract the power of the sun to reduce global warming.

How do you launch a trillion lenses? With a giant coilgun, of course. I was hired as the coilgun consultant for the 7 kilojoule coilgun that was designed and built in England for this Discovery Channel episode.

I was an ‘extra’ on location during filming in the Arizona desert at an abandoned silver mine. There’s a good chance I'll be in the background a few times. Watch me unveil the massive coilgun when the talent arrives. See me carry empty jerry cans from a superfluous army truck. Wonder why my shoes are covered with gaffer tape. Admire my giant rubber high-voltage gloves on the lead f/x technician. Great fun, tell your friends!

For background, please read Prof. Angel's Feasibility Study PDF (1MB).

6/13/2008 - Completely restyled my entire web site in a gold theme. Replaced all Javascript navigation with PHP server-side generated links. New navigation with three levels (section, chapter, page) makes it easier to find topics. Stored all files in templates for Adobe Dreamweaver CS3 to greatly simplify future updates. Added file version control using AccuRev. Other than that, nothing changed!

Broken links? Missing bookmarks? Please tell me so I can fix it, thanks!

6/10/2008 - Added the Low Cost Impedance Analyzer article reprint with the author's permission. You will find tons of great electronics projects in the Nuts & Volts magazine!

5/20/2008 - Added the EasyUnitConverter.com tool link for capacitor values to my capacitance page for a wide variety of unit conversions. The site can even convert shoe sizes. Check it out!

5/19/2008 - I bought the domain names electromagneticsoftware.net, electromagneticsoftware.org to help protect my business. All of these automatically take you to the main site at electromagneticsoftware.com.

2/7/2008 - Updated the Pulsed Linear Induction Motors with a new easier-to-navigate copy from Braam Daniels.

1/15/2008 - Added a major new thesis paper on Pulsed Linear Induction Motors by Braam Daniels, a talented engineering student in South Africa. He presents the theory and construction of a robust PLIM demonstrator, written at a level which is perfect for hobbyists (like me!).

1/11/2008 - Fixed the RLC simulation applet by recompiling it using Java version 1.4.2_15. This allows nearly everyone to run it without requiring them to download the latest Java executables.

1/06/2008 - Updated the RLC simulation applet. The colors and details are easier to see and use. There are not really any new features, but code has been restructured for improvements that will follow.

10/20/2007 - Updated the inductor simulation applet. It now supports much larger coil sizes (for all you crossover network designers out there), along with new eye candy. The coil shading lends a more 3D look, while the shading itself is proportional to the actual wire size chosen.

9/7/2007 - Updated the list of my trusted parts suppliers.

Thumbnail graph of critical damping comparison7/30/2007 - Analyzed the response of a critically-damped versus an undamped RLC circuit. The mathematics tell us the peak current is 1/e (or 36%) of the undamped (or very high-Q) circuit. This explains why my Mark IV coilgun was a little disappointing. So learn from my lesson: do everything you can to minimize resistance!

7/29/2007 - I bought the domain name coilgun.net, and configured it to redirect all requests to this site (coilgun.info).

5/5/2007 - Updated HTML on all pages to pass validation requirements. As a result, most of the time-stamps at the bottom of each page were also updated. My apologies for the headfake; there is no new content this time. (But your browsers will be happier!)

3/16/2007 - Added "Backyard Ballistics" Chapter 12 from William Gurstelle's popular cannon-and-mortar book. This provides a very inexpensive way to measure velocities of bullets fired from almost anything.

1/17/2007 - Added a large chapter on the Coilgun Mark IV. You will find my most successful coilgun yet, and a wealth of design information about it. This brings my totals up to 194 web pages with 29.2 MB of information. Enjoy!

1/1/2007 - Welcome to a new year! This coilgun web site has moved to a new domain and new web server at a new ISP. If you have linked to my old pages (http://www.coilgun.info/home.htm) then please update your links to my new site (http://www.coilgun.info/). The old pages were removed in May 2007.

12/12/2006 - Updated my e-mail address on all pages to barry@coilgun.info. Although I've been with OzNet for more than eight years, their e-mail service has become unreliable and their spam filter is worse than useless.

11/28/2006 - Added the Coilgun Mark IV title page. This is a place holder while the remainder of the chapter is entered. Also re-ordered the chapters in reverse chronological order, so the most recent coilgun is displayed first as you thumb through the chapters. Hopefully this will move the oldest and least-developed ideas to the end, and help you read the latest developments first.

8/3/2006 - Converted the Chapter 10: Electronics Now 1996 article to HTML to make it easy for humans to read and for search engines to index. This will greatly improve usability of this modern design, especially since some of the artwork has been carefully redrawn. For now, the original scanned pages also remain, to help readers verify the translation accuracy.

7/14/2006 - Found another magazine article! An alert reader pointed out that Popular Electronics published a levitator design in 1989, and he sent me scans of all the pages. These are now available on my web site at Chapter 11: Popular Electronics, May 1989. Enjoy!
PS - My apologies to those who bookmarked levitator pages, but I changed some folder names to help track when articles were published.

6/10/2006 - Updated copyright symbol and changed copyright year to 2006. No other textual changes.

Levitator from LNS Technologies 6/8/2006 - Added a new chapter about the updated levitator kit from LNS Technologies. The web pages give you schematic and design information, along with pictures and comments about building the kit. Conclusion? It's a fun and reliable little levitator that is inexpensive and easy to build.

5/26/2006 - At last, the linear momentum machine has been spotted in the wild! An alert reader says it comes from the Lariat Chain, a twelve-foot kinetic sculpture by Norman Tuck. Read more about it at www.normantuck.com and find an exhibit at a museum near you.

3/26/2006 - Added link to Electronics for the Evil Genius to my links page.

battery load tester 3/23/2006 - The biggest problem in coilgun construction is finding the big capacitor. The only cheap and available source is from disposable cameras. But car batteries are very common and store a huge amount of energy. It just so happens that I have two used batteries handy, but first I need to see if they're in good condition. So I built a battery load tester and measured their performance. Later, I will try them with coilguns.

2/22/2006 - There is a clever trick for measuring speed with a sensing coil. I've always wondered how well it works to detect an unmagnetized projectile, so I built one and took measurements with an oscilloscope. It seems very promising and it will be the first thing I try when I get around to building my own speed trap.

1/30/2006 - Rewrote the Visual Levitation topic into an entire chapter, including the inventor's biography and patent applications. It includes x-ray images of the lifting coil, and comparisons between the patent and actual apparatus.

Levitation from Electronics Now, 19961/9/2006 - Fixed the missing page 86 from the Popular Electronics maglev article.

12/19/2005 - Added another chapter about a magnetic levitation design from Electronics Now, February 1996. With six transistors and two op-amps, this design features modern easy-to-find components and overheating protection.

12/13/2005 - Added a chapter about a magnetic levitation design from Popular Electronics, May 1966. A simple schematic using only three transistors means simple construction.

12/11/2005 - Fixed the levitator topic about Designing the Lifting Coil to show the correct wire size. The wire is actually 24 awg and not 18 gauge. My mistake, it should have been obvious that 1,341 turns of thicker wire such as 18 awg would never fit into such a small coil!

12/06/2005 - Added a page about Levitator Simulation Using PSPICE. What a great way to validate and test your designs before ordering parts or building anything!

09/27/2005 - Added a link to the William Harriss Gauss Pistol on my page of coilgun links.

09/22/2005 - A major revision to the RLC Simulator applet now allows a huge range of input values. For example, you can dial from microvolts to megavolts, picofarads to terafarads, and so forth. The graphic display is auto-scaling to show you the circuit's initial response to any condition. Enjoy!

08/28/2005 - Added a link to Madgyver's High Voltage Realm to my page of coilgun links.

01/17/2005 - Added more theory about inductors. First something about inductance and reactance, and then how to measure inductance, and finally phototransistor spectral response.

animated eye from KITT television show01/10/2005 - A new project! Here is a captivating custom mod for your computer, guaranteed to be noticed. You can make your computer look like the famous KITT car of the Knight Rider TV series. A simple project, inexpensive and easy to build. What a babe magnet -- if it works for David Hasselhoff, it will work for you!

01/08/2005 - Update the Mark 2 schematic so that it matches the wiring shown in the photographs. The original datasheet did not seem completely reliable, so it can be a bit problematic to get working. Please note the pins on the Silicon Power Cube are not numbered sequentially, so be sure to use the numbering stamped on the device as shown in the power cube close-up photo.

12/31/2004 - Fixed the NE555 timer schematic for the Mark 1 oscillator. It will be easier to build from, now that I re-labelled the pins in the natural (top-view) order.

11/25/2004 - Updated the Mark 3 pages again. Also replaced my site map with an automatic javascript site map, which keeps itself synchronized with the rest of my web site.

coilgun with external iron8/30/2004 - Updated the Mark 3 pages. Added results of the first voltage sweep, which achieved 6.8% efficiency. The external iron is promising!

6/27/2004 - Updated the Links page. Brought the URLs up to date, and removed a few old missing ones. I was sorry to see that Obwan's "Nail Shooter" has gone to the Internet Bit Bucket in the sky.

12/20/2003 - While Googling on conventional motors, I came upon this almost-lost article. So I added a page on salient pole motors to my site. It tells you why early motors were not practical, and which invention made them highly efficient. Read it to learn the origin of terms such as armature, rotor and stator. Great background.

12/18/2003 - Added a description of a linear momentum machine, and how to build it. You know that angular momentum (a gyroscope) is strange -- it turns out that linear momentum is equally weird! Try this simple project!

11/28/2003 - Updated the Java applet to compute inductance in an LC circuit. It now supports an edit box where you can enter any arbitrary values, and it computes the inductance. Source code (but not batteries) are included.

11/07/2003 - Added a new Java applet to compute inductance in an LC circuit. Simply select your capacitor and desired time interval from the table, and read the inductance needed to provide it! Source code is included.

9/30/2003 - Added my own Maglev Over Hard Drive page. Fixed broken link to Visual Levitation.

9/19/2003 - Added the Levitation Kit by Guy Marsden to the top of my list of levitators.

8/14/2003 - Replace prev/next page navigation with Javascript. Ahh, peace at last! Now I can easily add or move web pages without tedious and error-prone linking by hand. I fixed several pages that were variously unlinked somehow, or that didn't show up in the site map. Look around, I think you'll find something new!

7/29/2003 - Updated mailing address and web link for LNS Technologies on the Buying Levitation Parts page.

6/19/2003 - Updated inductor simulator applet with new wire sizes and new features. It now supports AWG, SWG and metric wires. The coil length can be longer than before (up to 150mm long). It also tells you the winding density in "turns per cm". And there are several bug fixes.

5/22/2003 - Added page with the equations for a damped oscillator, to help out some guys at the HV Community. This is also good for computing oscillator frequency, and the part values to make a critically damped circuit. Enjoy!

5/20/2003 - Added Mark 3 coilgun pages, which uses a laminated transformer core around the coil to improve performance.

5/8/2003 - Updated FEMM script for a hollow cylinder. What was I thinking? The old one wouldn't work because of an obvious script error. Oops.

3/25/2003 - Added Overview of Electromagnetic Guns, a 1980 article from IEEE Transactions on Magnetics that gives a concise review of coilgun designs and their various capabilities. Be sure to keep some critical skeptism is mind, since it seems overly optimistic and may have been written by those seeking funding for further studies.

3/3/2003 - Added Slava Persion's Voltage Labs (http://www.voltsamps.com) to my Links page. Did you know there is a fun Coilgun Olympics you can enter?! Also updated link to Sam Barros PowerLabs to a new URL provided by Slava. I guess that Sam's old domain name is not coming back.

2/11/2003 - Analyzed several models using FEMM 3.2, and posted results in a whole new FEMM chapter. This includes how to model a coilgun, complete details for setup and simulation, sample source files, results, charts, graphs and conclusions. I think you will find this quite instructive!

12/29/2002 - Analyzed the affect of the coil's inside diameter on the projectile's speed. Would you have guessed that it's not very critical? A tighter fit and smaller air gaps always work better, but it turned out to be less important than I expected. Read all about it at FEMM - Coil Diameter.

12/22/2002 - Added FEMM analysis of the force on various projectile lengths. Want to know what length works best? These results will not be a surprise. Also added my site to Web Ring, but we'll see how this goes. The ring seems to have a lot of obnoxious advertisements. Let me know if it has some (or no) benefit.

11/17/2002 - Added FEMM analysis of the force on hollow cylindrical projectile. Want to know what size cylinder works best? The results may surprise you.

11/16/2002 - Removed iFAQ (infrequently asked questions). I need to save space since I've hit my server's 10MB limit, and these pages get no hits.

11/05/2002 - Added FEMM model of hollow cylinder projectile to see what happens with different projectile sizes. The results may surprise you.

08/03/2002 - Updated air-core inductor simulator so you can get the correct dc resistance value.

06/09/2002 - Updated levitator printed circuit board layout with revision 1.6 from Amadeus. Updated labels to better match schematic, and showed the jumper connections.

06/07/2002 - Added levitator printed circuit board layout by Amadeus.

06/02/2002 - Added theory page about "Force - Where does it come from?".

05/25/2002 - Restored the missing levitator pages. Added page about how levitator display frame woodworking including photos of other people's display stands.

05/12/2002 - Reviewed and fixed broken external links.

01/26/2002 - Improved my Theory home page to organize topics and make things easier to find. Added a detailed description of capacitor charging for laymen to the Theory section. I think this is a great introduction to how capacitors really work.

01/21/2002 - Updated link to US patent 5,763,812 on my Number of Coils page. It now points to the Delphion patent server that replaced the old IBM server. With a tip'o the hat to Mr.Bean for finding and reporting the new link!

11/15/2001 - Added links to levitator by Visual Levitation on the Links page. Updated the SCR wiring diagram to better match its photograph.

07/29/2001 - Read my Review - Visual Levitation Kit which is sold by this company in England. What an excellent product! Take it from me, you have got to get yourself one of these!

05/25/2001 - Updated RLC Simulator applet to v1.7 to offer a new range of values. The inductance is now 10 - 2,000 microhenries (uH) which is a much better range for coilguns. A large wire with a few turns has only a very small inductance. The resistance now covers 0 - 5.0 ohms, which makes it a little easier to adjust. And the time scale runs from 0 - 40 msec to make it easier to read faster speeds.

05/12/2001 - Updated the levitator schematic with a label for each part. Added an image map so clicking on a component will link to its circuit description.

04/04/2001 - The levitator printed circuit board by Amadeus is ready! See my Buying Parts page, or contact Amadeus, or visit his Maglev PCB Web pages. Hats off to Amadeus, woohoo!

03/29/2001 - Added a levitator printed circuit board by Amadeus to the Buying Parts page. Just contact Amadeus at amadeus@postmark.net.

03/22/2001 - Updated the levitator schematic to show the power connections to pins 4 and 7. Added a line to my Links page to a valuable bibliography of inductance calculations.

03/04/01 - Added some levitation testing hints, and put a subject line into all the 'mailto' links in the levitation pages.

02/16/01 - Added several pages for levitator testing and adjustment. This should be a great help to build it and make it work. A friend of mine in England is working on a printed circuit board. Write to Amadeus if you are interested!

01/18/01 - Fixed the levitator schematic to remove the erroneous connection.

12/20/00 - Major update to the links page. I know it's been long overdue.

12/15/00 - Added a page about FEMM modelling of a coilgun, along with all the model files themselves. Drew graphs and conclusions from the model about the effect of various projectile lengths.

12/03/00 - Fixed a link to the source code for the Java RLC simulator.

09/03/00 - Corrected some equations on the wire loop simulator, and added a small graph. Have made good progress on the Java applet but still need to fix the drag-n-drop user interface. Stay tuned.

08/13/00 - Added a mathematical analysis of the magnetic field of single wire loop, the simplest possible form of a solenoid. A bigger coil will then be nothing more than adding the effects of all the single loops.
Also added the first part of a web page for a wire loop simulator. When finished it will greatly help to visualize the field strength. The web page and equations are all there, but I'm just starting to write the Java simulator applet. Stay tuned.

08/05/00 - Added detailed description of capacitors and how to connect multiple capacitors in series and parallel.

07/19/00 - Rewrote the RLC simulator for better accuracy and more information. It will optionally show the capacitor voltage. Added a page explaining capacitors.

06/22/00 - On the levitator home page I added more photos of levitator lifting several small steel objects. There's even a cheezy MPG movie file (476KB) of it lifting a ball and washer, that looks vaguely like a UFO!

06/08/00 - Added a link to magnetic levitation - science is fun for all kinds of maglev devices.

05/01/00 - Added photo of power pack connections to levitator page. In the on-going battle between man versus chaos, I added new levitation web pages about feedback loop control systems, feedback loop equations, concepts of Bode plots, and designing a phase lead network.

04/18/00 - Explained how to connect two identical power packs in the levitator to get both positive and negative voltages.

04/14/00 - Added page describing how to measure the projectile's speed, using simple measurements and basic ballistics.

02/28/00 - Measured the effect of a non-conductive firing tube of the Mark II coilgun. Now the performance is up to 9 m/s! Also reformatted the results pages, as it was getting too long.

02/24/00 - Measured yet more results of the Mark II coilgun. I repeated the speed-vs-voltage tests with a significantly longer projectile. Now the performance is up to 7.8 m/s and the efficiency reached 2.7%!

02/21/00 - Measured even more results of the Mark II coilgun. I analyzed the effects of external iron on performance, and studied a wide voltage range to see what happens. Now the performance is up to 7 m/s and the efficiency reached 2%!

02/20/00 - Measured more results of the Mark II coilgun, this time using projectiles of various lengths. Quick answer: Shorter projectiles go faster. Kinetic energy was about constant over a modest range.

02/19/00 - Fixed the part numbers for the levitator's infrared emitter/detector pair at Radio Shack. I'm happy to say one ambitious high-school student wrote to say he's challenged himself to build a levitator! This is great, I'm sure he will be pleased when he gets it working. I've started getting parts for a new Mark III coilgun, but have nothing useful to report yet. Stay tuned.

02/14/00 - Added more construction details to the magnetic levitation pages. Added a page about power supplies. Seems like more high-school students are getting interested, but I'm still waiting for proof it can be built successfully by that age group.

01/24/00 - To answer some popular requests, I added a page to levitation about buying the parts. It does seem to be the science fair season coming up! Allow plenty of time, this is a big project for anyone in school!

01/15/00 - Added a page about What is an SCR? to the Mark II coilgun section. This explains about SCR's in general, and the silicon power cube in particular. Thanks to Adam for his continued interest.

01/08/00 - Added several photographs to the magnetic levitation section. This includes a clearly labelled parts diagram. Thanks to NathanP for his interest in building a levitator.

01/05/00 - Corrected the labelling of npn and pnp transistors on the coil driver circuit section. Thanks to NathanH for pointing this out.

12/28/99 - Added an iFAQ section (in-frequently asked questions), so you can read what others have asked.

10/26/99 - Labeled the SCR (S1) on the schematic diagram of the Mark II coilgun.

9/6/99 - Added a parts list to the schematic diagram of the Mark II coilgun.

8/28/99 - Added photos of Mark II construction.

8/20/99 - The Mark II coilgun result is 5 m/s when fired at 23v! It's very preliminary, but you can begin reading construction details. Also added an RSACi rating tag to my home page. This is my guarantee there is no nudity or violence at this site.

8/12/99 - Moved all pages to a new and shorter root URL. It also provides more web storage space for me. Also added safety warning to the RLC simulator page.

7/25/99 - Updated inductor simulation to replace Wheeler's Formula with the correct equation for a multi-layer air-core coil. Also added wire diameter size, for countries that don't use AWG (american wire gauge), and removed the packing factor calculations.

7/10/99 - Added a Java program for inductor simulation to help you choose your coil's physical dimensions.

6/24/99 - Added plea for help on SCR control circuit design on Barry's Coilgun Mark II. Can you help?

6/8/99 - Updated RLC simulation analysis to version 1.2. Made the ranges smaller for both resistance and inductance, and shortened the elapsed time from 200ms down to 100ms. This should make the results more representative for coils which are made from thicker wire.

6/7/99 - Added an RLC simulation analysis for how it applies to coilguns and what it means to your design. It's a fairly basic discussion without very many equations. Thanks again to RG for lending help.

6/2/99 - Added an interactive Java RLC simulation to the Mark 2 design pages. Try it out, it's fun! This applet makes a good Java example program so I'm giving away the source code, too.

6/1/99 - Added a quick thought on spin stabilization to the Tube Size web page. Thanks to RG for this idea.

5/31/99 - Added magnetic circuit analysis of a coil surrounded by iron. This includes diagrams of dimensions and the magnetic field, and equations to derive the general equations for reluctance.

5/20/99 - Added descriptions from RG about increasing magnetic field strength in Mark II Hints.

5/16/99 - The antigravity relay works! Updated all the pages in the magnetic levitation section. This thing is cool! Now this is real honest-to-goodness antigravity!

5/11/99- Updated launch speed calculations. Thanks to CD for pointing this out!

4/11/99- Updated navigation bar on all pages to include a link to my site map. Updated image tags to always have "alt=" text to help people who don't download images. Changed some page headings to add "Barry's Coilgun Whatever" because Excite is indexing my lower pages as better matches for "coilgun" than my home page. Go figure. Check back in a couple months to see if it helped.

3/24/99- Added long list of hints and suggestions to Coilgun Hints and Suggestions. Added some links to Links. Added another book to the Bibliography page.

3/20/99- Added magnetic levitation to describe a whole new project that suspends a ball in mid-air using an electromagnet with a feedback control circuit.

3/18/99- Removed disclaimer about "still working on pages for NetScape". If you have problems or suggestions for NetScape or any other browser please send me email. Thanks!

3/16/99- Received many great design ideas for my next model of a coilgun. Many thanks to Bob for his tips! See Mark II for the information.

2/28/99- Added breadboard page to describe the construction of the timing electronics.

2/27/99 - Replaced the background wallpaper on all pages. Now it looks a little more like engineering notepad paper. Started building a magnetic levitation device for the children's science fair. If it works okay I'll document it on the web. But will I ever get going on the next coilgun? Sheesh.

2/25/99 - Modified most circuit diagrams to have a transparent background, instead of stark white.

2/20/99 - Dumped MS FP98 and am now hand-editing all pages using MS Visual InterDev v6.0. So there, Microsoft! The good old Dept Of Justice is nothing compared to this brazen display of market choice. Oh, that's right, it's still from Microsoft. Oh well.

2/5/99- Results of testing found the Mark I coilgun achieves 1.7 m/s when driving a single coil at 12 vdc! Imagine the coilgun mounted on a table four feet high, and hurling a tiny screw the incredible distance of four feet before it hits the ground! Now I need to energize more coils and tune it up, to compare actual results with the original estimates.

1/26/99- Added photo of coil winding jig to the coil winding page.

1/23/99- Added table of magnetic materials that lists the composition of many common cores used in magnetic circuits. Updated the conclusion in saturation, and less significant updates to about this site, bibliography and winding coils. I've started designing the Mark II coilgun, but it's still a long time until I can post any documentation.

1/18/99- Added photos to coil gun goals and projectilesand winding coils, and a minor update to power supply. Added counter to this page, since this is where most bookmarkers should go first.

1/16/99- Added background on inductors and diode protection for inductive kick-back.

1/15/99- Added further explanation of magnet wire to the page on winding coils.

1/14/99- Added first photoof my coilgun. Fixed navigation errors for dumb old Netscape Navigator. Now, what's the point of having a disclaimers page that says I only support IE4, if Netscape users get Error 404 before they can read it? Pardon me, but I have to go do a little more testing now.

1/12/99 - Added some pictures to home page, disclaimers, magnetic saturation, and coil size pages.

12/31/98- Finished conversion to CSS and MS VI6. Rewrote or added pages on power supply, number of turnsand solenoid theory. My last-chance changes for 1998. Whoopee.

12/25/98 - Started adding cascading style sheets. Begin the switch to MS Visual InterDev 6.0.

12/23/98 - Added link to a neat site, How Stuff Works: Electromagnet.

12/21/98- Added several pages of theory of design and other design issues worthy of consideration. Thanks go to Lissandro for prompting me to clarify the ideas.

12/19/98 - Changed navigation, changed theme, changed socks and underwear. Organized topics as mechanical or electrical. Reduced massive size of flux field animation down to 274K. Still too bulky, I know, sorry!

12/12/98- Added description of magnetic flux lines around a screwinside a coil. Added gif animation (278K) of flux lines as a screw moves through a coil.

12/9/98 - Added copyright to all the web pages. (As if anyone cares!)

12/7/98 - Updated the coil driver page with descriptions of the 2N2955, replacing the '3055.

12/6/98- Added a visual animation of firing the coilgun on my Photos page.

12/5/98- I am wiring the output stage, using open wiring across four rows of terminal strips. This part (the head end) would be a perfect place to do a little circuit board! Maybe next time. Let me make sure it works, first. Won't finish it today; had to stop to find the pin-out for 2N2222 transistors. You'll find the URL to those specs now on my Links page.

12/4/98 - Discovered the 2N3055 power output transistors have their collector tied to their case. This would expose a hazardous supply voltage to users. So I changed to the complementary transistor, 2N2955. Its collector is also connected to the TO-3 case, but since the collector is at ground potential this is not a problem. I've got the mechanical placement of the gun parts done, but still need to do the wiring.

11/26/98 - Added "next page" navigation buttons. Now you can easily page through this information like a book, without going up and down through the web page tree. Added counter to home page. Wound my third (and probably last) coil, but still need to mount the coils in some kind of fixture and build the power coil driver stage. Hopefully I'll have time to do that over this Thanksgiving weekend.

11/20/98 - Fixed a few broken links in these web pages. MS Frontpage does not get along well with a Unix ISP. The case of filenames is important but FrontP insists on building its internal links in mixed case, even after I rename the files to lower. (Thank you, Microsoft.) Bought the 2N3055 transistors I need to build the high power coil drivers.

11/17/98 - Posted these web pages for the first time. Electronics are built and tested, but it only drives LEDs. The coil drivers are not built, and I still need to wind the third coil. Also need to pick up some 2N3055 transistors. The spreadsheet for coil #3 timing isn't quite right -- it assumes the last coil provides as much force as two coils. I need to measure its performance separately and plug different force figures into the spreadsheet.

  < Previous Page 2 of 13 Next >