I recently purchased a replacement explosive gas sensor for a storage area and realized that the meter had been very neatly relabeled with the appropriate text. They were buying 0 - 20 ma gauges and then affixing new text on the meter faces for the application at hand.
@Max The Magnificent The new text was on several small spot labels that covered the old text. If you have access to an old lettering guide and a good fine point permanent pen that might also work well for small captions.
@DrQuine: The new text was on several small spot labels that covered the old text. If you have access to an old lettering guide and a good fine point permanent pen that might also work well for small captions.
I think this option would be very low down my list of solutions -- I want every aspect of my projects to make the observer gasp "Wow -- that is amazing -- let me buy you a beer!" LOL
@Max The Magnificent It seemed to me the highest quality (even color) practical solution would be achieved by laser printing on glossy "HP photo paper" and then using double sided tape or glue to hold it on the plate. I believe there is enough space between the plate and the needle to allow the addition of a sheet of paper.
@DrQuine: It seemed to me the highest quality (even color) practical solution would be achieved by laser printing on glossy "HP photo paper" and then using double sided tape or glue to hold it on the plate.
I'm currently leaning this way, possibly using spray adhesive to get a nice light even coat...
Max: If you are going to print the faceplates for the meters take a look at "Meter" and "BasicMeter" software from Tonne Software. BasicMeter is free and Meter is $35. You can download the manual from their website.
@JGrubbs: Max: If you are going to print the faceplates for the meters take a look at "Meter" and "BasicMeter" software from Tonne Software. BasicMeter is free and Meter is $35. You can download the manual from their website.
Hi there -- I just checked into the hotel in Sao Paulo for ESC Brazil -- I'm up to my armpits in alligators at the moment -- but I will look at these apps as soon as I get a free moment.
As a former South Floridian who routinely went wading in the Everglades on fishing trips, this advice: Alligators are fine, unless it's a momma guarding the underground nest. Otherwise they don't bother you if you don't bother them. Watch out for the crocodiles, though; THEY are NASTY (as are the water snakes).
If the background of the scale is still nice and white then you can get some correction fluid like "wite out" or "Snopaque" and cover just the numbers and letters but not the scale markings. Then use Letraset dry-transfer lettering to replace the letters and digits. You can get it on eBay and at many craft stores in the scrapbooking section.
If you decide to re-print the scale markings and everything, you might try getting an inkjet printer that will print on CD's. You could easily modify it to accept the meter scales.
@Max...re printing on CDS...great idea....you could get an old CD, carefully cut out part of the CD the same size as the meter face, put the meter face in the hole thus created, attach it with stickytape on the back of the CD and faceplate, and print. You might have to pad the faceplate up a bit - it probably would not be as thick as the CD.
One thing I'd vaguely considered was to sand the faceplate down (using very fine sandpaper), spray-paint it white, and then add the new annotations by hand using a very fine indelible marker. But the more I think about this, the more I think the result would look absolutely horrible
But more realistically Victorian! In my blog Touring as an Engineer, I mention the Pitt-Rivers Museum where the labels on the exhibits are either handwritten or written with a typewriter with a rather grungy ribbon.
ALL D'Arsonval (moving coil) meters are the best type, and the basic design is ALWAYS a DC current meter. Many of these have a movement wiith a full-scale range of either 50uaDC (the expensive ones) or 1maDC. These can be made to display other functions or ranges by connecting either a shunt resistor (for higher FS current) or series resistor (multiplier) to change to a DC voltmater. For AC, the meter may be a moving-vane (e.g. Shurite type, usually relatively cheap) design which will work for AC or DC (although scale factor may be off), or uses a rectifier (typically bridge) along with a multipler or shunt. VERY often, the shunt, multipler, and/or rectifier is EXTERNAL, so you CAN'T go by the faceplate in determining the meter configuration! It's pretty easy to tell, thpough, with a DC power supply, some resistors, and a multimeter. Assume it's a "naked" DC milli/micro-ammeter, connect the PSU, a suitable current-limiting resistor, and the multimeter (in ammeter mode) in series and see what the meter does when the PSU is turned on. Ther rest of the process (and how to calculate appropriate shunt/multiplier values) is left as an exercise for the student!
PS: examining the photo of the disassembled meter, it has an internal shunt THAT CAN BE REMOVED. That would restore the basic movement range etc. so you can use it! Same for "voltmeters" except the multiplier is often external; if it is internal, it's also easily removable.
Also, nearly all faceplates are symmetric; thus no need to scrape. Just flip it over and paint! I've used that trick many times. If you have an old drafting tool/ pen set, the compass is terrific for draing the scale arc (if you can find some India ink.....). I have a couple of sets (including one older than I am).
I suspect this (AC) ammeter also has a removable rectifier in it; the clue is the "dead zone" between 0 and 2A, where the voltage across the shunt is below the band-gap voltage of the rectifier bridge. Looks to be actually 1.4 A, so assuming Si diodes, that tells me the shunt should be close to 1.0 ohms. Isn't it amazing how I can do the "Sherlock Ohms" thing from this far away? Thus my constaint complaint about the negelect of basic physics in today's EE curriculum.
I remember as far back when I was an apprentice in an instrument test lab, we had a guy who's job it was to re-calibrate moving coil meters for aircraft.
He would also turn the dial over or just re-paint as mhrackin suggested, then use a compass with an ink pen attached to re-draw the new scale. One thing he always did was inject various know signals then mark where the needle rested (i.e. calibrate the meter), he would then use those marks to accurately reproduce the scale markers (with the aid of a straight edge). He also hand wrote the scale values and they looked really good (good enough to put in aircraft in fact).
Could I suggest that you use the bigger meter for the minutes. Resolving 60 scale marks on a small dial might be difficult and most certainly harder to read.
Use PCB design software to create the new reticle and then get photoplots made. Use the old faceplate as the back for the new reticle. The pcb design software will allow you to make very accurate thin lines. If photoplots seem too expensive you can try printing on clear overlay material. If you think the reticle + overlay is too thick, you could paint the back of the reticle or find a different backing.
Steve, you HAVE to be a Southerner at heart! When I moved South about 40 years back, I quickly learned some of the secrets of "talkin' Suthrin." #1: The law of the redundant adjective: always add an adjective before every noun. Example: a writing instrument is NOT just "a pen"; it's an "ink pen" so as not to be confused with the "pig pen." I never met anyone who said "ink pen" who didn't grow in te southern US.
@Steve: How come your User rank has dropped to Rookie?
Frig -- it's because I have two accounts -- an old one and a new one -- and I havenlt found a way to combine them -- but thanks for pointing this out -- I've just switched over to my "Max the Magnificent" persona (you may kneel)
@mhrackin There might be another reason that southerners say "ink pen". There (at least in Texas) the word "pen" is pronounced like "pin" so by saying "ink pin" it is distinguished from a "hair pin" or a "sewing pin".
@DrQuine: There might be another reason that southerners say "ink pen". There (at least in Texas) the word "pen" is pronounced like "pin" so by saying "ink pin" it is distinguished from a "hair pin" or a "sewing pin".
Having lived for 3 years in Texas (Dalllas area), I think you may be treading on dangerous ground! In my experience, "real" Texans tend to NOT relate to "the South" and conversely the "old South" states refuse to acknowledge any kinship to Texas. At least in my part of the South, "pen" is pronounced closer to "pain." More rules for "speakin' Suthrin"single vowels become dipthongs, and vice versa....
Strange how these threads get onto all sorts of extraneous topics (including food, as MHRackin pointed out on another blog). Not that I am complaining, apart from the fact that I have better (but not as entertaining) things to do with my time.
But seriously.... Max 30 years ago in Rhodesia I got a job in an Electronics Lab. The guy I took over from was just finishing a transmission measuring set project and he had some large square meters for them. He got a firm to produce for him some plastic sticky labels for the new faces. If he could do that 30 years ago in the backwater of Rhodesia, I'm sure someone could do that near you. Yes, you could just buy laser labels, but paper tends to discolor fairly quickly and shows the dirt more. but then you could get a can of photo-protect spray and try that to protect them a bit better.
As MHRackin points out, you can turn the faceplates over - then you don't have to worry about the old markings coming thru if you get them screen-printed. But is this worth it for a couple of meters - I'd imagine the costs of preparing the screens would be a bit?
AC meters - As MHRackin also points out, (he's a clever guy I must say) you need to look at the inside of a meter before abandoning it. Moving iron meters are generally produced to a range (eg 5 amps) and there is not much you can do about it, but if you find a moving coil movement (and I am not being rude, that's what they are called) inside, then take it apart further and look for shunts or muliplier resistors. Once you get at the bare meter - the coil connections - you can mess around and find out the FSD and the meter resistance and set about getting it to do what you want.
Max, don't give up on those AC meters. Most AC meters will read DC, though may be nonlinear. near zero. For your custom-scale purposes, that might be OK.
While you have the scale plate off, check the internal wiring of the meter. Many AC meters are actually rectifier-driver DC meters.
High-voltage meters usually have external or internal "multiplier" resistors in series with a low-voltage low-current movement. Many high-current meters have low-resistance current shunts in parallel with low-voltage, low-current movements.
@traneus this is true, but only if the basic meter movement is of the moving-coil type. If it is moving iron, forget it. it will either have a coil of thick wire if it is an ammeter, or of thin wire and probably a multiplier resistor too if it is a voltmeter, but even if you take the multiplier resistor out you will have a fairly insensitive meter, needing a fainr bit of current for FSD. Most AC ammeters are of the moving iron type, they are cheap to produce and rugged.
I have a moving-magnet center-zero DC meter made probably before 1920, likely before 1900. The meter has three terminals connected to two windings (one terminal is common to both windings): a low-resistance, few-turns winding for current measurement, and a high-resistance, many-turns winding for voltage measurement. The meter is so insensitive that it dissipates 4 watts at fullscale deflection! The voltage winding measures 30 ohms, and gives fullscale deflection at 11 volts DC. Perusing an electrical-equipment textbook copyright 1891, showed this was reasonable at that time.
@traneus ... " it dissipates 4 watts at fullscale deflection"
Sounds about right. We use cheap moving iron meters for battery monitors in our radio sites. The voltmeters are 15V fsd and run around 12-14V all the time. The bare meter sensitivity is around 2-3V I think, so they have a high wattage multiplier resistor built in. After a few years of service the plastic faceplates go brown because of being in proximity to the hot resistor for so long. BUT I've never yet seen one go wrong!
PS - keep your meter under lock and key, Max'll be after it for his projects!!
The meter in the photographs was made by Weston Instruments, likely in the late 1950's, in New Jersey. I grew up there, and got my BSEE from Newark College of Engineering (now part of NJIT). Edward Weston was a major benefactor of the college; the main building was Weston Hall (which may actually have been the original home of Weston's company). That is almost certainly a moving-coil movement; I don't think Weston made moving-iron, as their meters were high-end and high quality. I probably have a couple in my basement (bought surplus in the '50s or '60s).
I have done this in the past in the same way you basically describe. I scanned the original faceplate and used the image to create vector artwork in AutoCAD. A test printout on plain paper allowed precise measurements to be made for correcting any scale errors.
Then I either printed the final image on high resolution flat paper or glossy photo paper intended for inkjet printers and used spray adhesive to attach it to the original metal faceplate. The slight added thickness of the paper has never been an issue.
The results in both cases looked as good or better than the original faceplate but had the advantage of color printing if neccessary.
I have used the same technique to make front panel art for prototypes but instead of paper or white film for photographs, I print reversed on a transparency film intended for overhead projectors which I turn over when spray attaching to the front panel. That allows the tough and chemically resistant Mylar transparency film to protect the printing.
Re " how did you get to insert the image?" It's easy when you wear undergarments of authority. I think it depends on how the image is placed on the source web site, and the format. I've managed to paste a couple that were in img format, but no luck with JPEGs. I know how painful it is to do from numerous personal experiences, but you ought to talk to the UBM IT security folks about that. Certainly "editors" SHOULD have the privilege of inserting images. It may be the legal eagles advising the IT people to block all image posting as it could be a case of copyright infringement! (or embedded spyware, etc.) Happens at least 0.001% of the time, so block it all!
I've actually seen a fair number of those around here, both of city streets and the freeway. However, I'd say they're pricey for what you get.
Of course, I also see plenty of Teslas (especially), Leafs, and Volts around here; maybe if you spend a lot of time stuck in traffic, a full electric car makes more sense, since you're not using much energy while idling. (Then again, a lot of people do 100->200 mile round trip commutes, which is stretching it for an electric).
If you still have an old flatbed plotter, a bunch of refillable pens for it, an old PC with an old version of Autocad and a serial interface for your plotter, a graphics tablet interfaced to your Autocad PC, you could enter your old meter face into Autocad using the tablet calibrated mode on an enlarged copy of your meter face.
You could then play around with some paint and thinner to get the right consistency for the pen to apply the paint to your dial. It's also helpful to slow down your plotting speed if your Autocad driver allows that.
You could then apply shim material to the tracks of your plotter so the pen would be at the right height for the dial plus double sided tape.
You would then do a dry run on a piece of card of the right thickness and take measurements to accurately locate your dial.
You could then paint the back of the dial white and plot the meter face on it.
Nothing like using old technology for working on still older technology - a great make work project. ;-}
Back in the early days of (passive) surface-mount chip parts and thick-film hybrids (ca. 1969-70) I proposed a project to develop a non-contact soldering method for attaching e.g. chip ceramic caps (040 by 080) to thick-film substrates. It would use a 5W or so CO2 infrared laser with servo-control of position, focus point, etc. Management (rightly so in retrospect) thought I was crazy, so project never got funded. However, that would have also been the perfect tool for "burning" your meter faces!
After you do up your artwork on your PC, you can laser print it out on the the iron-on resist material intended for prototyping PCBs. Then simply locate the transparent print properly on the repainted rear of your dial and iron it on.
What you are essentially doing is transfering the laser's toner from the plastic sheet on to your dial's painted surface using the heat of your iron.
@cookiejar: After you do up your artwork on your PC, you can laser print it out on the the iron-on resist material intended for prototyping PCBs. Then simply locate the transparent print properly on the repainted rear of your dial and iron it on.
While I was kidding about using paint in an old flatbed plotter, (I still have all the equipment I described functioning), I wasn't kidding about the Iron-on Resist. The company is called Techniks with the usual commercial extension. The catch is that you need a laser printer.
Shameless inkjet gripe: I got my sons a cursed Kodak ESP 7, the usual inkijet cartridge cash cow - cartridges drying up after about a month and the printer insisting you had to change them all, until a cartridge finally blew up gumming up the works.
Now for a shameless plug: After much previous research I got the boys a Brother MFC-8910DW B&W laser. The selling point is that a genuine $100 Brother cartridge does 8,000 pages - not the usual $100 for 2,000 page variety from most manufacturers. (400% advantage) Most of your run of the mill PC and office supply chains, who are into the ink and toner business, don't handle this heavy duty office machine which COPIES and prints both sides, has WiFi, does 42ppm, scans legal size, and has the lowest cost/page. But you can get it from Amazon ($320) or serious office and laser suppliers. Amazon also sells 8,000 page new TN750 clone toner cartridges from China for around $20 that work as well for us. Brother also recommends cheap copy paper. It's a welcome addition to my son's university house full of engineering students and everyone gladly chips in for the cheap supplies. Inkjet supplies are a serious burden on students. Our previous equivalent Brother model has worked flawlessly for 3 years without a single jam.
P.S. I've been informed that the iron-on resist has probelms with late model Brother printers. You can't win them all.
PnP Blue produces high quality prototype PCB resist layouts making your design ready to etch. PnP Blue is a Mylar (Polyester) backed material in which several layers of release agents and resist coatings are applied. An image is printed or photocopied onto this film, using a laser printer or photocopier (dry toner based), and subsequently ironed or pressed onto a cleaned copper clad board. The image area applied to the film is subsequently transferred to the copper board, along with the high quality resist (blue). The film is removed and resulting board is ready to etch in ferric chloride.
Last time I checked, the laser etcher was nearly $20,000. - out of the question for most.
Iron on resist sells for $1.65 to $1.05 a sheet depending upon the quantity. Mind you, you then have to deal with ferric chloride and copper chloride which can be rather nasty.
This past weekend, I constructed a handy-dandy little unit-- you connect a meter to it and use the unit to work out the value of serial resistance required to drive the meter without blowing sensitive meters up. It worked -- Happy Dance!
I'm planning on writing an article about using MCUs to control analog meters for use in hobby projects (there are lots of potential "gotchas" when it comes to working with surplus meters). Would anyone be interested in reading such an article?
There is more than one way of doing this. If it is something that you are throwing together, then a fine point sharpie on the other side of the faceplate might be enough. A step up would be to laser print the sticker you need and adhere it to the faceplate. Office supply stores sell clear adhesive sheets that you can print on. You could paint the other side of the face plate (e.g. white) as others have mentioned and then adhere your clear sticker to the faceplate.
Alternatively, you could look for "custom decal printing" that pretty much do the same thing, but will send you a vinyl sticker you can adhere to what you want. A seller on ebay is offering this service for around $10 with shipping. Also check out 'www.doityourselflettering.com for something similar.
But if you want perhaps the most refined method, then you have to go with screen printing. Paint is more durable than stickers esp. for panel lettering. You can use your laser printer to make silk screens. But the faceplate you have might be too small to work with (as when you screen it needs to be flat against what it is screening). So if it was me, I might build a small silk screen frame 6"x 8" as example, start with a similarly guage metal panel as the old face plate and a little bit bigger than the frame, paint the panel flat white, laser print the mask (and transfer it to the screen). Then screen the new panel. After that using a jeweler's saw cut your new faceplate from the panel and file away the burrs. Then drill the holes (from the back so you do not mar the front! ) using a drill press. I imagine this is the top shelf "deluxe" method I have seen very rarely done. As it would be the most involved. But you also get the most professional manufacturer-like results possible. I welcome others to suggest better.
Also, there are number of youtube videos that show how to screen print (that show the intermediate steps I left out). Search "screen print at home".
@technos: Alternatively, you could look for "custom decal printing" that pretty much do the same thing, but will send you a vinyl sticker you can adhere to what you want. A seller on ebay is offering this service for around $10 with shipping. Also check out 'www.doityourselflettering.com for something similar.
@technos: But if you want perhaps the most refined method, then you have to go with screen printing. Paint is more durable than stickers esp. for panel lettering.
I agree, but I don;t know if I want to go to all this effort myself because I've got so many other projects on the go - on the other hand, there is a certain satisfaction in doing everything from scratch.
And then there is a professional screen-print "shop" just round the corner -- when I have the files for what I want, I might saunter over to visit them to see what they say.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.