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bonanz

Led display Digital Voltmeter question

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Hi all,
Where can I get the "EXACT" PCB pattern layout for this project? I tried to used the layout in this post but everytime I print it out it's always oversized..
I set my printer to 1:1 but to no avail..


It is written in the article that you must set your printing software to resize the layout to 35% of the original size, or use the dimensions in milimeters that are under the picture on the article.

It works perfectly.

Regards

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Hello...
Before starting to do this circuit There´s something i must know!!

I want to place this circuit in a power suply which goes from 0 to 20V
......and i was wondering if it this circuit displays the voltage with two decimals or only one.....(when you are using the R3 for measure from 0 to 20 v obviously)......
I hope it uses two decimals because if not I will have to find anotehr circuit....
I imagine you already notice that my english is terrible....that's because 0m from Argentina.....so.....sorry for my english...

Thanks....Chau!!..Saludos desde Argentina

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Hello...
Before starting to do this circuit There´s something i must know!!

I want to place this circuit in a power suply which goes from 0 to 20V
......and i was wondering if it this circuit displays the voltage with two decimals or only one.....(when you are using the R3 for measure from 0 to 20 v obviously)......
I hope it uses two decimals because if not I will have to find anotehr circuit....
I imagine you already notice that my english is terrible....that's because 0m from Argentina.....so.....sorry for my english...

Thanks....Chau!!..Saludos desde Argentina


Hello, i´m from Brazil.

When measuring from 0-20V, this circuit displays 2 decimals.

Regards

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Hi......I'm here again........with more doubts :-\
First of all i would very happy if another person corrovorates if this circuit displays two decimal when measurin from 0 to 20.

And my other question is: Which R1 should i use!!!?? 180K or 100K (in the datasheet and in the eagle circuit says 100k but I'm not sure what to do!!!)

Is there another correction in the values of the resistors or the capacitors???

Thank you very much.......I will be waiting for your answer (I want opinions!!!)

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Sorry....i forgot to say something........in the pcb all the pin 5 of the MAN6760 (which is the pin of the dot in the display) are send to ground!!!.........IN THAT CORRECT!!!??? (i don't think so)...

OK that's all.....thanks again........

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In browsing this forum, I believe I have seen corrections posted for this circuit. Some were in the "General" area. I do not recall where but there were two different places that it was discussed. Perhaps a search could help you.

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Hello

I just wantes to know what is the purpose of REF HI and REF LO pins, also does the above schematic has a 2.000 volt full scale or not .

In AN023 application note, it is said that to obtain 2.000 volt full scale, pin 29 cap must be 47nF, pin 28 resistor must be 470 K, and pin 27 cap must be 220nF. Is that right. I noticed that you done the opposite.

Thanks

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I am building the same circuit as discussed earliers. I want to attach the meter to a supply and measure the same supply. I find its not possible as the ground and the common is not same.

I am attaching the circuit to a 12V supply using a 5V regulater. then monitor the same 12 V supply. How can I do this? Thank you for your help.

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Benz, you cannot power any digital voltmeter from the supply you are measuring. You have to provide an unchanging supply voltage to the meter. There are a few ways to do this. Primarily, you will want to pull the supply off the secondary side of the transformer somewhere and not from the variable output. You can do this in many cases by just adding another regulator, etc.

MP

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Guest Kasamiko

I just finished mine on a breadboard..but when I powered it, The digits that was displayed was NOT zeroes but random numbers if I try to adjust the trimmer but only the leftmost digit display "1" I check my display segment by connecting PIN# 37 to +5V and all are ok..
Did I missed something.. ???

Rhonn ;) ;)

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Guest Kasamiko

Hi Ante, can you point me to the tested and working schematic for this project. I got a lot a ICL7107 sample chip from Maxim and Intersil and I'm planning to build a regulated power supply with digital readout for voltage and current respectively..
Maybe this circuit will do the job.
http://www.electronics-lab.com/projects/power/032/index.html
Regards.


Rhonn ;) ;)

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Guest Kasamiko

I have found this this updated and corrected schematics..
But want to clear this out.. Based on the two posted schematics, is PIN #30 connected to PIN #32 and 35 or what??
Thanks again..

Rhonn ;) ;)

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stuee,

Yes, this circuit can measure current if you like. You need a shunt for this.

Ante ::)



Ante,

What would the circuit look like and what value shunt resistor would be needed to enable the meter to measure 30 vdc and 3 Amps

Greg

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Greg,
If you are building our "0-30V, 0.002-3A Power Supply", instead of adding a current meter with shunt in series with the load, which spoils the voltage regulation, why not monitor the voltage across its R7, which is already in series with the load and is outside the voltage-regulation loop. R7 will be the meter's shunt, and you just need to divide the voltage across it by 4.7 to get a 3A range.

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Hi Guy's

Sorry. I am causing all sorts of confusion here. To clarify....This digital volt meter is a great idea. I will build my own 0-30vdc variable supply at 3 amps. very similar to what you have on your site. However instead of using analogue meters. I would like to build this digital voltmeter into it. I would also like some detailed guidance from you knowlegable gentleman as to how to change the digital meter into a digital ammeter.

Your assistance would be greatly appreciated.



Greg

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This has already been answered here on the site. You just need to search. It was either in the digital voltmeter discussion or it was in the 0-30 Volt Power Supply discussions. I recall seeing a diagram posted to use the digital voltmeter for both volts and amps.
If you cannot find it, let us know.

MP

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