Fluke 45, replace dead VFD by 7-14 segment LED display´s

[james_s]

That really looks a lot better than I would have imagined. I don't think I'd have even noticed it wasn't original from the photo unless I looked really closely. I'm reminded that I have a Fluke 45 that I hardly ever use, I really must clean up the bench sometime and give it a more permanent home.

[lowimpedance]

Stirling job right down to the cable looming  .
Looks like there is a good amount of space to add the extra piggy back board on the 45.
 The 8840 does not have any more available space than the VFD so was quite a crush getting all the display and wiring in for my display mod.
I also used proto board too and as you say doing a PCB with SMD parts would have made it easier.
But for my 8840 the display bezel was beyond help as well so I had to rebuild that too anyway and thus the choice of red LEDs.
The blue LEDs and bar graph do look much nicer though.

[Cubdriver]

Wow - that's an amazing job - very nicely done!     I'm not familiar with that meter, so at a glance I thought the first picture with the lighted display was of the other, working meter you said that you have.

Look forward to seeing the finished product once you get the missing '-' symbols and the text mask over the indicator lights and button it up.

-Pat

[bitseeker]

It is amazing isn't it? The blue LEDs really give it the VFD look & feel.

[Cubdriver]

And how!

-Pat

[bitseeker]

Almost makes me want to add badly faded Fluke 45 meters to my shopping list. Oh, my aching TEA.

[james_s]

If you wanted to really go the extra mile, find some of those big flat faced rectangular LEDs and laser print masks on waterslide decal film. Apply that to the LEDs then paint the sides black to prevent light bleed and you'd get the nice alpha indications too.

[Satbeginner]

Hi all,

again some progress (baby steps): the (I choose Red for negative) single digit 7-segment displays arrived today, so I put those in.
The only thing I still have to do is find the A4 polyester film so I can print the "letter-mask" for the indicators.
(Difficult in a small Spanish pueblo....)

I managed to make the mask in "Word", using a monospaced font called 'Lucinda Console'.
It needed some playing around with the character size and spacing but using size 5 and spacing extended with 0,6 point gave me a 0,1" spacing like the LED-bars.
I also shrunk the line-spacing using 'exact 5 points', so I could use 3-chars terms like 'CAL', 'BAT', 'MIN', etc.

When I can print this on a transparent film in real black on my laserprinter it should work OK. (the picture is still paper)

Un saludo,

Satbeginner

[Satbeginner]

P.S.

although cool on the outside, it's only fair to show the inside too, in real life, having a compact display-board like this means a lot of wires!!

Un saludo,
Satbeginner (Leo)

[Richard Head]

Gosh I've just found an old Fluke 45 VFD in my junk box. Do you want it?

[bitseeker]

That's quite a bundle of wires all right. Next generation goes to PCB.

[james_s]

Well if you can find a few people who need one, there might be a market for a nicely done PCB. In the meantime just keep the cover on and nobody will ever know. It's sort of like software, if it looks good on the outside nobody has to know your code is a mess, at least that seems to be how it works.

[Satbeginner]

Gosh I've just found an old Fluke 45 VFD in my junk box. Do you want it?

Hi, I would like to have it, because I have a second 45, so you never know.   

Can you send me a pm please with the cost and shipping?

Un saludo,

Satbeginner (Leo)

[Richard Head]

Satbeginner I'm pulling your leg! After all that good work I thought that you'd tear your hair out if you managed to get one in the end.
Actually I do have one but it's in my (working) Fluke 45.
Nice job and don't be too angry with me.

[Satbeginner]

No worries, I already thought it was to good to be true.

And now I can say I have (probably the only one in the world...) a Fluke 45 with a color display. :-)

I love a practical joke!!

Un saludo,

Satbeginner (Leo)

[Dtec]

I'll give you a fluke 8840a with bad vfd for the board to replace another 8840 a also own a fluke 45 dual display will pay for that board pm me with price


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[Satbeginner]

I'll give you a fluke 8840a with bad vfd for the board to replace another 8840 a also own a fluke 45 dual display will pay for that board pm me with price

Hi Dtec,

I am afraid I do not completely understand your question/offer:

I do not have a board for sale, I also did not make a special PCB for the display repair, I just did a "one time off" breadboard project to revive my Fluke 45.
The simple schematics I used are in the beginning of this thread, anybody who want can use these.

I re-used the VFD display driver chip, and put some simple components in between so it could drive the LED's with several mA's.

Very soon I will post pictures of the final result, I am still waiting for the laserprintable polyester foil.

Un saludo,

Satbeginner (Leo)

[bitseeker]

Congrats, Leo, on your first product request. The confusion is understandable given the fantastic results you achieved.

I went back to the beginning of the thread and scanned the posts on the first page, but didn't see the schematic you referred to.

[Satbeginner]

Congrats, Leo, on your first product request. The confusion is understandable given the fantastic results you achieved.

I went back to the beginning of the thread and scanned the posts on the first page, but didn't see the schematic you referred to.

I posted the basic "schema" being just a transistor driver per digit, and a current limiting resistor per segment.... :-)
To be clear, I used the VFD driver chip, I just replaced the VFD by a basic driver circuit and 7-segment LED displays.

For both the numeric displays I used a 5-digit display with shared segment pins.
The minus signs needed to be separated, because the share indicators as well.
For the indicators -like AC, DC, m, V, Ohm, etc.- I used LED "volume-type" bar arrays. (they have their own current limiting resistor as well)

Un saludo,

Satbeginner

[bitseeker]

Ah, OK. Got it. Thanks, Leo!

[Satbeginner]

Today I (finally...) received the polyester film for my laserprinter, so I could print a "display mask".

I am not happy yet, because the black around the indicators (m, V, AC, etc.) is not black enough, but it "sort of" works.

Un saludo,

Satbeginner (Leo)

[bitseeker]

Yeah, it's going to be hard to block all the light with a thin layer of toner. What if you use two masks to double the density of the toner? Does it create any side effects (diffusion, fringing, etc.)?

[Satbeginner]

Yeah, it's going to be hard to block all the light with a thin layer of toner. What if you use two masks to double the density of the toner? Does it create any side effects (diffusion, fringing, etc.)?

Will try that this weekend by printing the same mask 3 or 4 times on the same sheet, and then cut them all and put them together, so I'll have multiple layers.

Keep you posted.

[james_s]

You could get a really nice result if you can find someone to plot it on photographic film. Especially something like xray film that has an emulsion on both sides. You can get really nice solid black with film.

[eliocor]

You can prepare a .PDF and go to printing service shop: they can print your file on film which have a very high density and resolution (not less than 2400DPI).
When I need to make some (homemade) PCB prototypes with very small geometry (5-6 mils) I prefer to use such service: the cost is about 10€ for an A4 film (but only 22€ for an A2+) and the results are optimal!