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LCD Panel Meter - need advice

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jst3712

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Hi. This might be really simple, but I bought a new 3.5 digit 'LCD Panel Meter' today and need some help in wiring it up, as these things aren’t exactly cheap, and I don’t want to connect it incorrectly and ruin it. So I was hoping somebody - who is familiar with them - might be able to help.

I have attached the data sheet that came with it.

This one is a 12-pin module and they didn’t exactly provide nice examples to work with.

I want to be able to measure DC voltage (only), up to 20 volts. Decimal points = 2.
Also would prefer to use a zener diode instead of a 5V regulator is possible.
I don't understand what some of the pins are for, and how to hook them up :confused:

How would one wire this thing up? -- Schematics would be nice, thanks! --

Thanks.
Jason.
 

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mvs sarma

Well-Known Member
Hi. This might be really simple, but I bought a new 3.5 digit 'LCD Panel Meter' today and need some help in wiring it up, as these things aren’t exactly cheap, and I don’t want to connect it incorrectly and ruin it. So I was hoping somebody - who is familiar with them - might be able to help.

I have attached the data sheet that came with it.

This one is a 12-pin module and they didn’t exactly provide nice examples to work with.

I want to be able to measure DC voltage (only), up to 20 volts. Decimal points = 2.
Also would prefer to use a zener diode instead of a 5V regulator is possible.
I don't understand what some of the pins are for, and how to hook them up :confused:

How would one wire this thing up? -- Schematics would be nice, thanks! --

Thanks.
Jason.
you may simply use the attached PDF diagram from Altronic. You need a series resistor chain of 2 resistors R1=100K ohms and R2=1K ohms (better 1010 ohms (1K+10 ohms). across the input voltage.

R1 top side would be connected to input 20V DC. and R2 bottom to ground
the voltage across R2 would have to be connected to input pins of DVM.
Then it would give you a working voltmeter for 0 to 19.99 V DC. a schematic is show in attached 2nd drawing.
It is always preferable to use regulated 5V.
 

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  • 0 to 20V DC setup.GIF
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jst3712

New Member
you may simply use the attached PDF diagram from Altronic
] it would give you a working voltmeter for 0 to 19.99 V DC
It is always preferable to use regulated 5V.

Hi Sarma, I just realised, after viewing your attachment, that Altronics had the data on their website; I'm guessing that's where you found it :eek:

The datasheet on their website is a little better compared with the one I was supplied with "in the box", so I will use that one - It shows a voltage divider that connects to Pin 6 (and recommended resistor values).
And the circuit diagram you posted from the site also helps me with the decimal point connections.

I now feel more confident. Next time I shall look a little harder, haha.

Thanks again! :)

Jason.
 
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jst3712

New Member
Hmm, it seems to be working abnormally.
I have 2 decimal points for some reason (e.g. ".01.2", and it doesn't matter what DP (DP1/2/3) I have connected to pin 10... no effect whatsoever.
Also the digits increase or decrease by itself for no apparent reason sometimes, regardless of the voltage applied (to be measured). I have a feeling it may be faulty.
 

Shutterspeed

New Member
Jason:

I noticed your thread and the problems you were having with your voltmeter. I am using mine for a different purpose, but you mentioned it was expensive. I was in the process of building a overrated boiler control panel and I was looking at cheap, acurate voltmeters, which are going to display temeperture up to 200 degrees F. I found some Velleman units for $9.00 and some change that can be configured for 200MV, 2 VDC, 20 VDC,200 VDC. Some of there other units will go up to 500 VDC. I cant remember who I bought them from but if your interested I can get the name. I just did a search on velleman. You would probably need a divider circuit for the 20 VDC input.

Shutterspeed
 

mvs sarma

Well-Known Member
Hmm, it seems to be working abnormally.
I have 2 decimal points for some reason (e.g. ".01.2", and it doesn't matter what DP (DP1/2/3) I have connected to pin 10... no effect whatsoever.
Also the digits increase or decrease by itself for no apparent reason sometimes, regardless of the voltage applied (to be measured). I have a feeling it may be faulty.

please check your wiring for the Dp2 and Dp1 may be touching perhaps?
or the company has wired for dp1 and you added dp2 without removing dp1 connection?
If you have too long wires on IN+ and IN- this problem would come
 
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