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Grogster

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Posted: 08:44am 14 Mar 2023

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Hi everyone.

I need to customize an MU45 standard analog moving-needle type meter to show between 0 and 3v.

There are various versions of the MU45 available at Jaycar etc, but I no longer have the data for the multiplier or shunt values to customize these meters.

Can anyone suggest a meter type and suitable multiplier for 0-3v use?

Thanks.

WHY do I need an analog meter in this day of digital?
I need to build a RSSI meter, and analog meters are still the best for this - IMHO.
I have a RSSI output of 0v to 3v to play with, so I need to arrange for a MU45 meter of any type, to show 3v at full deflection/range.

Smoke makes things work. When the smoke gets out, it stops!

pd--
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Joined: 11/12/2020
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Posted: 09:58am 14 Mar 2023

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https://littlebirdelectronics.com.au/products/large-3v-analog-panel-meter

its a adafruit unit so probably available at a few different suppliers

phil99

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Posted: 11:55am 14 Mar 2023

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The Jaycar site indicates the MU45 coil is 1mA FSD so for 3V you want a total resistance of 3k. The coil resistance isn't specified so measure it and replace the existing series resistor with one that gets a total of 3k. Or just use a 5k multiturn trimmer and calibrate it.

Grogster

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Posted: 11:21pm 14 Mar 2023

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Both excellent suggestions - thanks, chums.

I used those analog meters in my teenage years, but that was quite some time ago, so I have forgotten the details about working out the multiplier or shunts.

Smoke makes things work. When the smoke gets out, it stops!

Chopperp

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Joined: 03/01/2018
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Posted: 01:24am 15 Mar 2023

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Hi Grogs
You may be interested in this for drawing meter scales. Sorry it's a Windows prog.
Bit fiddly but works quite well. I do have the paid version.

Brian

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Grogster

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Posted: 02:35am 15 Mar 2023

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Sounds excellent.

If I get the prototype going OK on the bench, perhaps I could get you to whip me up a scale seeing as you have the paid version?

Only needs three colour zones left to right: RED, YELLOW, GREEN for weak, OK and good signal levels.

Smoke makes things work. When the smoke gets out, it stops!

phil99

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Posted: 07:19am 15 Mar 2023

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Any of the 'Mites drawing commands could do a simple scale like that.
You don't even need one with a screen with Peters latest phantom LCDPANEL and SAVE COMPRESSED IMAGE.

Chopperp

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Posted: 08:47am 15 Mar 2023

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@ Grogs
Found a MU-45. Will have a quick go. I had to open the program up for another task anyway.

@ phil99
You are probably right

Brian

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Chopperp

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Posted: 12:15pm 15 Mar 2023

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Hi Grogs

I take it back. The program is very fiddly & works sort of sometimes.

See what you think of the attached. Some cutting out is required & may need upscaling a tad. Was OK on 210mm A4 on the screen, but the test PDF printed out slightly smaller.

Brian

Grogs test MU45_09.pdf

ChopperP

phil99

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Posted: 10:20pm 15 Mar 2023

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"PDF printed out slightly smaller."

It probably added margins and re-scaled the image to fit. Some programs have an "actual size" option to prevent that. If not save as PNG.

Grogster

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Posted: 03:20am 16 Mar 2023

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Thanks, Brian - I should be able to work with that!

Smoke makes things work. When the smoke gets out, it stops!

Chopperp

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Posted: 07:56am 16 Mar 2023

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@ Grogs. Great news. Let me know if updates are required.

@ phil99. Points noted. Thanks.

The program has the facilities for printer calibration. I used 2 printers for doing this project; a Brother mono laser & Microsoft print to PDF. I did the cal for each which were slightly different. I didn't try my colour inkjet as it is a bit low on ink.

To print correctly, the calibration needs to be done with the printer doing the actual printout.

As this was intended to be a demo for Grogs, I just wanted something in the ball-park. His printer may be slightly different to mine anyway & give a slightly different print size out.

I did wonder if the margins did come into play but I wasn't particularly worried. No problems in doing a other one if Grogs says there is room for improvement.

Brian

ChopperP

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