Updates
Updates
(I will often find errors on my updated pages, within a day or two after the official update. I just go back and fix them without further ado. So, if you notice something amiss shortly after a site update , there’s a good chance it will be fixed within a day or two. But if it doesn’t get fixed in a reasonable time, please let me know about it.)
2016-05-29
•Due to some problems with the .ods format spreadsheets on my Downloads page reported by Excel users, I’ve created .xls versions of the files and posted them there.
2016-04-15
•Added a new construction project as a companion to the switch mode B+ power supply. It is a Current Sensing Switch that monitors the current drawn from a radio’s filament supply ‘A’ Battery, and turns on the ‘B’ supply boost converter when it senses that the filaments have been switched on.
•Added a page explaining my low tech method of soldering surface mount parts.
2016-03-07
•Added a new page to the ongoing Numerical Methods for Inductance Calculation pages. The new Part 4 is a fairly lengthy article discussing the subject of Geometric Mean Distance.
2015-09-07
•Added a page discussing the Practical issues involved in matching a short antenna to a low power broadcast band transmitter.
2015-08-24
•I’ve rebuilt the entire site and it is currently live. If you’re reading this, then you’re looking at the new site. Yes, it looks almost exactly the same as the old one, but the HTML is much cleaner, and I’m hoping that this will fix some minor glitches on the Calculator Pages, as well as some other items. If you experience any problems please Contact Me. Otherwise, this will become permanent.
•I’ve added a note on the 6U5/6E5 Solid State Substitute Page listing current sources of the circular LED display.
2015-03-02
•Added a new project: Magic Eye Tube Solid State Replacement. It’s a microcontroller based LED display that replaces 6U5 or 6E5 magic eye tubes in antique radios.
•After getting some feedback about how hard it is to find my various online inductance calculators, I’ve added a direct link from the home page.
2014-01-28
•Added new Online Inductance Calculator (Multi-Layer Coils). This is an omnibus calculator that, in addition to circular multi-layer coils, can calculate inductance of multi-layer polygonal coils (triangles, squares, hexagons, etc.), circular and polygonal flat spirals, as well as large diameter short loops (circular or polygonal, flat or box style) typically used for loop antennas. In essence: nearly any air core coil that you can wind.
2014-01-07
•Added a new project: Switch-Mode B+ Power Supply.
•Modified the Solenoid Inductance Calculator and Rectangular Coil Inductance Calculator so that they can now automatically calculate the insulation thickness of magnet wire.
•Corrected an error in the formula for the area of a polygon in Part 1b of Numerical Methods for Inductance Calculation. The formula had been incorrectly transcribed, but subsequent derivations and calculations are correct. It appears, this is the second time that I’ve corrected an error in that formula. I apologize for my carelessness.
2014-01-01
•Added some brief Documentation and Operating Instructions for the Superhet tracking calculator. I wrote this a long time ago, but forgot to upload it to the site.
2013-12-11
•Added a new radio receiver construction project: A 3-Tube Superheterodyne Receiver.
•Added a page describing how to Add a Filament Winding to a Power Transformer, handy information now that tube project power transformers are getting harder to find.
•Cleaned up a few minor typos on various pages.
2013-05-03
•I’ve been experimenting with some of the graphics features that are available with the HTML5 specification, which most of the current web browser versions support (even Internet Explorer, surprisingly). This opens up many new opportunities for web site features. The web version of my Bandspread Calculator produces the same numbers that the downloadable Tracking Calculator application does (see downloads page), but until now, didn’t produce any graphics. As an experiment, I tried to see if I could use the new HTML5 graphics to create the tuning dial graphic on the web calculator page. After much programming, debugging, crashing, and nearly destroying the entire website, the new version seems to be working. However, for those who have problems with the new version, the original bandspread calculator page is still available here, temporarily at least.
2013-04-22
•Added a new project: Tube Audio Amplifier. It’s a low power stereo tube audio amplifier (one tube per channel) to drive my computer speakers.
•Corrected an error in the formula for the area of a polygon in Part 1b of Numerical Methods for Inductance Calculation. The original formula had been incorrectly transcribed when the page was created, but subsequent derivations and calculations are correct. I've also corrected a few other minor typos on these inductance calculation pages, as I do from time to time, but unless the errors are serious ones, I don’t bother pointing out the corrections.
•And finally: A not so new page. It’s been here on the site for a few months, but there has been no way to navigate to it directly. It’s an analysis of Negative Resistance Devices using load lines. I don’t like to post pages that aren’t substantially complete, and this one still has much to be done. But since I posted a link to it from another site, and the search engines have found it, it’s only sensible to mention it here. Though, at the moment, the only link to it is the one highlighted above. It will eventually be listed on one of the index pages.
2012-09-27
•Made some revisions to the 6CQ8 AM transmitter project write-up and added some video clips showing real time trapezoidal scope traces.
2012-08-23
•Added a new project: AM-Stereo Transmitter.
2012-08-08
•Added a new project: Mystery Crystal Set.
•Minor edit to Part 2a of Numerical Methods for Inductance Calculation.
2012-06-29
•Added Part 1d of Numerical Methods for Inductance Calculation, which discusses methods for analyzing the Mystery Crystal Set coil. An accompanying online Mystery Coil Calculator is also provided.
•Made further revisions to Part 3b of Numerical Methods for Inductance Calculation, to correct some inaccuracies in the discussion.
2012-06-12
•Corrected Inductance formula (34) in Part 3b of Numerical Methods for Inductance Calculation. While its derivation in the accompanying spreadsheet was correct, I had made a serious error in transcribing it onto the webpage, accidentally inverting two of the terms. My thanks to David Knight for pointing out this error as well as a slightly lesser offence, where I had incorrectly stated in Part 1a of Numerical Methods for Inductance Calculation that the date of Nagaoka's work was 1911, when the correct year was 1909.
•Also, in Part 3b, I've now added formulae (35), an SI version of the inductance formula, and formula (36) the equivalent empirical formula for Nagaoka's coefficient.
2012-03-15
•The Website has moved! But, obviously you've found it!
This site was previously located on my ISP's free webhosting service, which has been shut down.
The fact that you are reading this means that you've reached the new site. It's quite likely that you were redirected from the old site. If so, please update your bookmarks, because the redirect from the old server is temporary. The new URL, as you've no doubt discovered, is as follows:
http://electronbunker.ca
However, I'm encountering a few glitches here and there as I get things set up. Hopefully, they will be sorted out in the next few days.
2012-03-14
•This Website will be relocating to a new host!
I just received notice from my ISP that they will discontinue their web hosting service as of April 30, 2012. So, I will be relocating to a new host prior to that time. The URL for this site will change to
http://electronbunker.ca (corrected URL 2012-03-23)
This URL is now active, and will redirect to my current host until the site is moved to its future home. So, please update your bookmarks now, as I don't know whether my current web host will be able to redirect to the new site after April 30, 2012.
2012-02-09
•I made some further changes to the Solenoid (Round Coil) Inductance Calculator and Rectangular Coil Calculator so that they now allow the entry of AWG conductor sizes larger than 0. Previously, it was necessary to enter the larger sizes in millimeters only. The underlying structure of these calculators has now been made sufficiently general, that future calculators will be much easier to add. I expect to create a calculator for polygonal loops in the near future.
2012-02-05
•I was so inspired by the results of the Rectangular Coil Calculator (see last two updates), that I decided to redo the original Solenoid (Round Coil) Inductance Calculator. It now has a slightly cleaner interface, and makes it easier to calculate close wound coils. I'm always paranoid about making changes to these things. Typical of any computer programming, one small change can have far reaching consequences. Though it doesn't look too much different on the surface, the structure of the underlying program has more significant changes. Ironically, unit conversion seems to be a bigger problem than actual inductance calculation. I ran many tests, and everything seems fine. However, I would appreciate hearing from anyone who experiences problems.
2012-02-03
•Made further refinements to: Rectangular Coil Calculator, which should make it more convenient to use, and more accurate for single turn loops.
2012-01-31
•Added a new online inductance calculator for rectangular coils and rectangular loop antennas: Rectangular Coil Calculator.
2011-12-16
•Added a new low power AM transmitter project.
2011-07-30
•Revised Part 1a of Numerical Methods for Inductance Calculation, to eliminate the ambiguity of the units used in the various formulae.
•Expanded sections Part 1b and Part 1c of Numerical Methods for Inductance Calculation, to discuss coils wound on coil forms which are polygonal rather than round.
2011-07-02
•Added a new section, Part 1c of Numerical Methods for Inductance Calculation, which treats several cases of multi-layer coils.
2011-03-20
•Nearly a year after I announced an imminent update to Part 2c of Numerical Methods for Inductance Calculation, I've finally had time to expand on the discussion, which now extends into Part 2d. The reason for the long delay is that, what I thought would be a rather simple adjustment to the helical inductance formula, turned out to be a compete re-derivation in order to avoid approximations in Snow's formula which made it inappropriate for use with coils of large pitch.
•Made some additional security changes to the site in order to deal with renegade websites hot-linking to images on this site. Unfortunately, if you are accessing this site through a proxy server, this may cause images not to load.
2010-12-22
•Fixed a compatibility problem with newer versions of Internet Explorer which affected operation of the Inductance Calculator.
•Changed some page formatting to prevent text from getting clipped, which could happen if the user's browser default font size was set higher than normal.
2010-11-28
•Another minor update to the FM Crystal Set page.
•Some technical changes to provide better compatibility with some language translators.
2010-11-07
•Updated the FM Crystal Set page.
2010-10-26
•Made a few security changes to the site, over the past couple of months, which may have inadvertently interfered with Google Translator's ability to display images from the site. My apologies if this affected you. It should now be fixed. (This does not apply to the Microsoft/Bing translator or the Yahoo/Babelfish translator, neither of which have ever worked with this site, and still don't work. I'm not blaming the translators; it's more likely the fault of my web design software, which produces web pages which are rather unfriendly to the translators.)
2010-06-29
•Made a number of revisions to part 2c of Numerical Methods for Inductance Calculation, as a result of further research on Snow's helical inductance formula.
2010-06-13
•Added example calculations to part 2c of Numerical Methods for Inductance Calculation, comparing the different calculation methods.
2010-06-08
•Added a new FM Crystal Set Project.
2010-05-26
•Added part 2c of Numerical Methods for Inductance Calculation, giving a new method of inductance calculation based on C. Snow's Helical Inductance formula, complete with program code written in Open Office Basic.
2010-05-11
•Expanded the discussion of tapped coil bandspreading in Bandspreading Part 3. There is now a summary showing the derived formulae so that the reader can skip the full derivation. The worked example now contains additional detail.
2010-05-01
•Added part 3b of Numerical Methods for Inductance Calculation, a discussion and optimization of Wheeler's 1982 inductance formula;
•Added a worked example and accompanying spreadsheet for Bandspreading Part 3, – Tapped Coils.
In doing this latest update, which includes changes to both the bandspread discussion and the numerical methods discussion, I thought it worth mentioning that I haven't adopted the most logical system for equation numbering. In both Bandspreading and Numerical Methods, the equation numbers start at one, and go up from there. So, there is duplication in the numbers. So far, fortunately, I haven't had to refer from one section to an equation in another section. At some point in the future, I see that I will have to renumber everything so that each equation no matter where it is on the site will have a unique number. Doing this revision will be fraught with danger, as I will make countless mistakes and it will take forever to clean up the mess. I don't look forward to it, and that is why I haven't done it yet.
2010-04-30
•Added parts 2b, and 3a of Numerical Methods for Inductance Calculation.
2010-02-16
•Added the first few sections of a discussion on Numerical Methods for Inductance Calculation;
•Added a 455 kHz signal generator project to the Projects page.
2010-01-17
•Added an On-Line Inductance Calculator.
2009-11-19
•Added an On-Line Bandspread Calculator;
•Added some photos to the Nixie Digital Dial page showing the final assembly, and posted the assembly language source code for the PIC controller. Sometime in the future, I will be posting the circuit board layouts and the program hex file. However, they still need some cleanup work before they are ready to be unleashed on the unwary public. If you are desperate and want an advance look, please contact me via my Contact Page.
2009-10-03
•Added Part 4 of the Bandspreading discussion
•Added a tuning characteristic “dial scale” for the example calculation on the Bandspreading Part 2 page.
2009-09-06
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This page last updated: May 29, 2016