GALVA

GALVA (https://www.f5bu.fr/galva-about/)  is a drawing program written by Jean-Paul F5BU that’s ideal for creating meter faces and front panel layouts..  Jean-Paul has installation instructions written in English (A_Lire-Read_Me.pdf) and a tutorial written in English (Galva_Tutorial.pdf) that describe Galva.  You can find these documents in the Galva directory after you have downloaded and unzipped the installation file. 

The Galva script commands are in French, but there’s only about 10 commands that you will need, so it’s easy to learn. 

Below is an example of a meter face that I made for a AC/DC voltmeter project using Galva.

With Galva meter faces are “drawn” using a procedural scripting language, a little bit like BASIC but without line numbers.  Goto’s and If statements can serve as a good way to skip a block of code.  And the apostrophe causes all following text on that line to be a comment.  There are about ten commands that you will commonly use.  Script commands that end with an underscore are logically continued on the next line.

Most of the script commands allow for many optional comma separated values.  Jean-Paul includes a feature he calls a mask (and which I think of as a form) to make editing of these commands very easy.  Put your cursor over any script command, press F2, and it will open a form where you can easily add, edit or remove options to that script command. Click the “Valider-OK” button on the form when you want to save that data and the results will appear in your script listing on the right side of the screen.  Press F4 to “run” the script and see the result of your changes on the left side of the screen.

Note that meter representation you see on the computer screen is just a rough-draft and what will be printed on your printer will look terrific.

Making a New Meter Face

When I start a new meter face the first thing I do is remove the old meter face from the meter and scan it on a flatbed scanner at 300 dots per inch (dpi) as a JPG image.  I’ll later include this scanned meter face JPG in my Galva script to use as a background for alignment of the new meter face.  To facilitate that background view, because the Galva script command to include an image as a background does not include a transparency setting, I will use an image editor to make several versions of my meter face scan JPG at different transparencies (usually 50%, 60% and 70%) and include that transparency value in the saved JPG file name (abcd-50, abcd-60, abcd-70).  That way when I want my background meter scan to have more “fade” and can just change the suffix of the image file name in my Galva script.

Next I find one of Jean-Paul’s example meter faces (fortunately, there are lots of them to choose from) that is close in style to what I want.  I then use Google convert all the comments in Jean-Paul’s example program from French to English.  Next, any variables that are composed of French words are changed English words.  I frequently press F4 while doing these language conversions to recreate the proposed meter face, to ensure that I haven’t mangled the script in the process of doing the language conversions.  Keep in mind that the actual script commands must remain in French.

I then comment out (or use Gotos or Ifs) to make most of the program blocks ineffective.  And then un-comment several lines at a time, to learn what those lines do, and how to change them to match my new meter face.  After doing this for ten to twenty minutes you’ll start to get the hang of writing scrips for Galva.

One of the things I really like about Galva is that it can make the meter face pickets (the little tick lines that are perpendicular to the arc scale) linear spaced at regular intervals, follow some mathematical formula, or even work from a table of values.  That table of values option is great when you are making a meter face for a meter that is driven by some non-linear circuit that doesn’t follow some nice mathematical formula, or to correct for errors particular to that specific piece of equipment (Hewlett Packard was doing this in the early 1960s  https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1961-03.pdf ).

Data File Location

When you install Galva you will be asked where you want your data files stored. The suggested default location will likely be located C: /Users/username/AppData/Roaming/Galva. You will likely find it more convenient to over ride this default location and instead use C:/Users/username/documents/Galva.

Below is a link to a DropBox folder with some of Galva scripts that I use for my meter faces.  These are just modest changes to the example scripts that Jean-Paul developed and included with Galva, for the meters I have and the applications I’m using with those meters for.  The Galva script file names begin with the intended meter size.

https://www.dropbox.com/sh/8c03vp49ocalhe5/AABiFXzTkvhRA3tarXO7pDsVa?dl=0

Printing Meter Scales

When I first started printing Galva scales I was pleased they looked so great on my laser printer but dismayed at how poorly they looked on my inkjet printer.  It turns out that using the Photo Paper and High Quality setting on my Canon MX870 printer was the problem.  Regardless of what paper I use the my Canon ink jet (photo glossy, photo luster, photo matte, premium copy paper or cheapest paper available from the big box store) I always get the best printing results of Galva scales when I set the inkjet printer driver to “plain paper” and “standard printing”.  The other thing I learned, at least for my Canon inkjet printer, is that if I want anything other than printer defaults, I have to configure the printer from Windows Settings>Devices>Printers.  Additionally, Galva will always print in portrait format, regardless of printer settings.  So if I want my 3.5×2.5” horizontal meter face to print horizontally on a 4×6 piece of paper, I have to use Windows Settings>Devices>Printers and set the printer for a custom paper size of 6” wide and 4” high, so that when Galva prints in portrait mode I essentially get a landscape output, because I told the printer to use a custom paper size of 6” wide.

I’ve settled on printing my meter faces onto Inkpress Media Luster paper using my old Canon MX870 inkjet printer, but any somewhat heavy-weight good quality photo paper should work fine.  Once I have the scale printed onto paper I do a rough cut with scissors (about a ½” wide around the whole meter face) and then glue the backside of the meter print to the backside of another sheet of the same paper using an Elmer’s glue stick.  That way I get a double thickness result and if there is a bend to the paper as it sat in the box for months (or years) the two pieces of paper, glued back to back, will offset the bend.  I then use a fresh Exacto blade and a straight edge to carefully cut the meter face to the lined dimensions.  For the cutout around the meter movement, I don’t even try to cut a circle, because I never get it quite right.  Instead my meter prints provide three straight lines for the cutout around the movement.  That I can do pretty well with the knife and a straight edge.  For the two holes on the meter face for the mounting screws, I use a drill press with a small drill to drill the holes and then clean up the drilled hole with an Exacto knife.  A razor-sharp punch would produce better results, but I don’t have such a tool so the drill press is my compromise solution.

Meter Sources

Like most hams who are builders, I have a small box of old Weston, Triplett, and Simpson panel meters.  But I can’t make myself take them apart and insert new meter faces.  I think that will have to wait until I’ve turned to dust and then the next owner of those classic meters can take on that task. 

Instead, I use cheap meter movements from Ebay and AliExpress.  When I want a larger display I use a 100x80mm meter and for midsize I use the 64x56mm meters.  I usually buy based on price and seller’s ratings, and I don’t worry too much about the meter’s “as sold” functionality, because I will drive them with an op-amp and a series resistor – I can change the series resistor value to suit the meter.   Most all analog meter movements themselves are natively current meters in the range of 50 uA to 5 mA.  If the meter is sold as a voltmeter there’s usually an internal series resistor.  If it’s sold as an ammeter there’s usually an internal shunt resistor, although I’ve seen some pretty weird amp meter shunts. In general, I’ve found it’s best to buy meters that are sold as DC 50uA or 100uA full scale. With those meters I have the most flexibility.

But if you have some other type of meter, you can usually return it to “native small current meter mode”. AC meters usually have some sort of a diode bridge internal to the meter (along with a series or shunt resistor).  To restore the meter back to its “native current mode” I open up the meter and remove any diode bridge, short any series resistor and cut out any shunt resistor, and then reassemble it.  I then connect the meter movement to a series circuit consisting of the meter terminals (now directly connected to the meter’s coil), a 100K ohm fixed resistor, an accurate digital multimeter in current mode and a 0-20 volt variable power supply.  I then adjust the power supply voltage for a full scale deflection on the analog meter.  If I can’t get full deflection I reduce the resistor value by a factor of 10 and try again.  Once I have the meter at full scale deflection I read and record the current value displayed on the digital ammeter multimeter.  I then remove the digital multimeter from the series circuit and if necessary readjust the power supply for full scale deflection.  I reconfigure the digital multimeter for measuring voltage and then measure and record the voltage across the meter terminals when the meter is at full deflection.  I then use ohms law to calculate the resistance of the meter coil (voltage / current).  For most meters in the range of 50 uA to 5 mA I usually get about 50 to 250 mV across the meter terminals. For a 50 uA meter the resistance is usually 2500 to 5000 ohms. For a 1 mA meter the resistance might be 100 ohms.

I’ve had few problems with the meters I’ve received via Ebay and Aliexpress.  When I have had a problem with a meter (sticky, jumpy movement) it’s always been (so far) that somehow the movement spring got hung up on the some element of the movement.  Maybe it was dropped during transit, who knows.  To correct the problem I carefully manipulate the spring with a toothpick to release it and that has always (so far) solved that problem.

In late 2022 and early 2023 I’ve purchased meters in the $4.50 to $6.50 range (includes shipping) on Ebay from seller yibiaoxin1982 and on AliExpress.com from JU QI Quality Store, TAIYEDQ Global Store and Zhongong Store.  The meters in the best cosmetic condition (pristine clear meter cover) were from JU QI Quality Store, but I suspect that all these sellers are simply reselling stock they get from a common distributor or liquidator, so what I got with one purchase may be different than what I get from the next purchase from the same retailer.

–ooOoo—