ok,, New Project time,,,

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dacflyer
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ok,, New Project time,,,

Post by dacflyer » Tue Dec 04, 2018 7:41 pm

ok, My old ROBERT SHAW RS-228 Propane monitor went belly up.
https://www.bakersgas.com/rs228.html
ROBRS228.jpg
ROBRS228.jpg (10.43 KiB) Viewed 222 times
i have kept this thing limping along as long as i could. but it is no more, and there is nothing on the market that is a stand alone device with a display.. there is wifi and BT devices out there, but all i wanna do is just look up and see a simple display that tells me the % of fuel.. i have a 100 gallon tank, it has the remote ready sensor on it.
http://www.rochestergauges.com/products/R3D-LP.html
lp guage.jpg
the specs of the hall sensor are....
Opp. Range 4.5 to 5.5 vdc/ratiometric.
Can be made compliant with alternative operating voltages.
Output Voltage with 5.0 Volt Input
Ratiometric 8-80% of input voltage @ 8-80% volume.
Ratiometric: Empty is 0.4 volt or 8% of input voltage.
Full is 4.0 volt or 80% of input voltage

I'd like to make me a display 2 digit 00-99 led display and i think i need the reading range to be like ( Empty = 0.4V =8 %? and Full = 4V = 80% ) according to the specs ? i think this may require a micro controller.. but i could probably be happy with the the old school LM3914 display.
just have to have advice on both. the LM3914 i can do, i just need to figure out how set it up for the particular range.. 0.5V min and 4V max ?
not sure how to calculate that.
if i do the code, i'd have to have someone write the code. i can only assemble.. an Arduino nano and an Adafruit display sounds easiest.

comments advice ?

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Janitor Tzap
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Re: ok,, New Project time,,,

Post by Janitor Tzap » Wed Dec 05, 2018 9:31 pm

Dacflyer,

So your still looking for a replacement for your old propane monitor.

I came across this one on youtube.
https://www.youtube.com/watch?v=4PTJ1KajJrc

This is the company that makes it.
https://mopeka.com/


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haklesup
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Re: ok,, New Project time,,,

Post by haklesup » Thu Dec 06, 2018 11:31 am

Since you have access to a proportional voltage, the hard part is done.

If you want Old School then get a mechanical ammeter movement, figure out the resistor network to get the needle to deflect full scale at 4V and replace the graphics behind the needle with a custom scale 0 to 100%. (assuming it has enough current at 4V, you didn't comment on that)

While you already have a mechanical needle display, Can I presume you want this to be remote and wired?

Maybe you really want digital, the divide the voltage by 4 so you have 1V Full scale and just use a voltmeter and pretend millivolts are percents

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dacflyer
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Re: ok,, New Project time,,,

Post by dacflyer » Mon Dec 10, 2018 12:16 pm

Janitor >> i don't want a wifi type or App type monitor.
i think i decided on using the LM3914 it'll be easier than a analog meter pointer from across the room.
i just need some figuring out done for me ( horrible at math ) i need to know what the voltage divider resisters need to be for a 4v or 5v full scale
i think this will be easiest.

i do also have now a CA3161 & CA3162 2 digit meter.. found them in my junk box,, they are out of some old C-Band dish movers.
so same thing i guess, if i can figure out the voltage dividers ( if someone is kind enough to help me out ) then i can make either display i choose..
the digital one would just be 00-99 range, but close enough for my needs, as a propane tank is usually considered full at 80% or so.
they usually can put in a bit more if it's going to be cold for a while.

either one i choose will be direct wired. no radios.

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Janitor Tzap
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Re: ok,, New Project time,,,

Post by Janitor Tzap » Mon Dec 10, 2018 5:26 pm

Sorry......

When I had looked at the video, the guy didn't say that it was Blu-Tooth. :(
Also, after going out too the Mopkea website and looking at the spec's of the unit.
The sender units only can be used with tanks as large as 30 gallon. :(

Here's the Ohms Law Calculator for Voltage Dividers.
http://www.ohmslawcalculator.com/voltag ... calculator


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dacflyer
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Re: ok,, New Project time,,,

Post by dacflyer » Tue Dec 11, 2018 7:56 am

i looked at that ohms law calculator.
problem is, i don't know what value resistors i need.. i only know the input voltage. and not sure about the output voltage.. is that even prudent to my project ?

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Lenp
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Re: ok,, New Project time,,,

Post by Lenp » Tue Dec 11, 2018 11:29 am

When the math fails, resort to emperical observation, roughly translated - get a potentiometer and just diddle with it to see what works best! :grin:
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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dacflyer
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Re: ok,, New Project time,,,

Post by dacflyer » Tue Dec 11, 2018 2:55 pm

i guess i could try that.. will i need 2 pots or just 1 ? i am thinking 2 of them..

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Lenp
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Re: ok,, New Project time,,,

Post by Lenp » Tue Dec 11, 2018 5:32 pm

One pot....
One end to the source
One end to common
Center to the input
It's a classic voltage divider
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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dacflyer
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Re: ok,, New Project time,,,

Post by dacflyer » Tue Dec 11, 2018 7:34 pm

oh, ok, so it does not have to be balanced on both ends.. ok,,
so 2 resistors = the total of a pot, and the wiper moves to my needed value..
ok,, sounds really easy now..
i'll give it a punt and let ya'll know later on.

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