Led display Digital Voltmeter question

[Gusk4x4]

By the way, there are some differences between the scheme and the PCB photo-layout

Is P1 a TrimPot, like the scheme says, or a Trimmer, as the photo and article describes?
Is the ICL34 pin correct in the scheme? Going out to the Display?
Where are the C6 and C7 on the scheme? They are not there, just in the PCB layout you can find and try to discover...

Finally, if someone corrected the scheme, I would apreciate to see it.

p.s.: I tryed to assembly it on the ProtoBoard (breadboard?).

Thanks very much,
Regards.
Gustavo Kowalski

 

[MP1]

Gustavo, if you scroll up to page 1 of this thread, Billy has posted some corrections to the circuit. I have also found a board layout file with schematic both in Eagle format on the Eagle site that uses these parts and is very similar. It was donated by a user. If you do not have the Eagle Layout program, you can get a free version from their website at the same time.
http://www.cadsoftusa.com/freeware.htm

Billy: did you find any other corrections needed after your previous post?

MP

 

[Gusk4x4]

Hello! Thanks for you reply.
I read Billy´s corrections, but I still do not know if its a TrimPot or a Trimmer, and I don´t know where the C6 and C7 goes.
It would be nice to make the corrections on the main site of the project, because I linked that site to many friends that looked for this circuit.

I´m getting this program you said, but where can I found the schematic? Thanks again and contratulations for the great site!

Regards.

 

[maestrodamuz1]

Having gone through the circuits, datasheets, replacement guides (ECG master replacement guide from Philips) and after the alarm about the inconsistencies I came out with these corrections and I believe they are correct as far as am concerned. Also I have included a modified circuit diagram for the DVM which can measure both ac and dc voltages. The maximum ac voltage that can be measured depends on the type of rectifier used; I recommend an IC rectifier which has a peak reverse voltage of 1000V and maximum forward current greater than 3A.So as not blow up the rectifier leave a safe limit of about 100V i.e for a rectifier of PRV of 1000 V don

 

[mixos1]

Hello Gusk4x4

If you use the PCB, this voltmeter will work very nice. There are some errors at the schem and maestrodamuz has poster here the corrections along with some modifications to measure AC exept from DC voltages:

http://www.electronics-lab.com/forum/index.php?board=4;action=display;threadid=353&start=0

Hope this clarify things

 

[blacksheep1]

Does somebody know how i can make a digital amperemeter? It's for a power supply...

 

[Ani1]

I tried to build the L.D.D.V. yesterday, using a breadboard and
I came up with peculiar readings on the LEDs. ??? I had followed the
schematic from smartkit.

I thought that I had a false ICL7107 and I dismounted the
components. :-[

Today I thought to check the data sheets of ICL7107 and MAN6960 in order to cross-check the connections. Found [glow=red,2,300]inconsistencies[/glow] in the
article schematic ! >

For example for the 1's display :

Article : ICL(6) -> MAN(10)
Should be : ICL(6) -> MAN(9)

another example :

Article : ICL(34)
Should be ICL(25) -> MAN(1) and so on... there are many there.

Moreover, the R1 should be 100K, not 180K, I refer to the datasheet
and the "Digital Voltmeter" project

Finally, the LCD dot, is pin number 5, emitted in the schematic.

I am about to search all the errors now and report back later,
after I will rebuild the voltmeter.

I attach the data sheets for further reference. 8)

Hi Billy,

After comparing the schematic with ICL7107 datasheet, I also realized those problems which are already mentioned by you.

If you have rectified those errors, and have drawn proper schematic, please put it on or mail it to me. I want to use it in my lab PSU.

Regards,

Ani

 

[mixos1]

blacksheep: you can use this Voltemeter as ammeter also using the connections see below:

You connect the ammeter in series with the load and voltmeter in parallel with load. To take a current measure there must be a load connected

Also you can read this: http://www.electronics-lab.com/forum/attachments/Digital_Panel_Meter.pdf
explaining different connections and R calculations.

Or use this to measure current:

 

[MP1]

Here is a schematic and board layout that was donated by someone to the Eagle site. It is free to use. It looks like the project, but might be a little different. If you have the free version of the eagle, you can view it or even edit it to be what you want. If you do not have the free version of Eagle, go to http://www.cadsoftusa.com/ and download it.

ICL7107.zip

 

[blacksheep1]

mixos: Thank you very much for your reply... i have one more question: I've made a digital amperemeter with a voltage-to-frequency-converter (LM131), an amv (NE555), some mmv's (MC14538), some bcd-counters (MC14518) and some bcd-to-7segment's (MC14511).... is it possible to build an ampere meter in the same way, or do i need a "ampere-to-frequency-converter"? sounds a little funny...

 

[mixos1]

First of all I attach here the FIXED SCHEMATIC (22-2-04):

I attach also two sample power supplies for this voltmeter:

Hope this one solves all previously mentioned inconsistencies. Also the schematic at the project's page is updated:

http://www.electronics-lab.com/projects/test/014/

blacksheep : To measure the current flows a load you use a small resistor in series with the load and you measure the voltage drop on it. Then with ohm's law you calculate the current pass throught the resistor and throught your load. You can't easily measure the current right away. So you can use the same circuit to measure the voltage drop across a resistor. For more info on how to do this see the pdf file i indicated previously.

 

[mixos1]

This is the FIXED SCHEMATIC (22-2-04):

 

[mixos1]

Here is a schematic and board layout that was donated by someone to the Eagle site. It is free to use. It looks like the project, but might be a little different. If you have the free version of the eagle, you can view it or even edit it to be what you want. If you do not have the free version of Eagle, go to http://www.cadsoftusa.com/ and download it.

These are the contents of the zip file for fast view of another 7107 digital voltmeter (it's almost the same, but this one incudes the +/-5V power sources)

 

[MP1]

maestrodamuz, I think you will want to relabel the voltages in and out of the LM317. I think you mean positive voltages here.

MP

 

[mixos1]

I done the corrections for you maestrodamuz! Thanks

 

[maestrodamuz1]

This is about the power source using the 1K resistors, I used the LM 317T for positive voltage because I found out the 7805 refused to work with the 7905, this I have tested over and over again beforew comin to that conclusion. A positive voltage enters the 317T and is varied until +5V is at its output.

 

[Kasamiko]

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..
please help.. :'(

 

[mixos1]

The best way to print it out correctly is to make some test prints to find the correct ratio. Take a part with fixed dimensions and try to fit on the print out paper. Then change accordingly the ratio to achieve the correct dimensions. It is better to use a program that allow you to change the percentage (%) of the print out and not the ratio.

I don't know another more "easy" way to print a PCB from an image file.

 

[MP1]

Kasamiko, if that will not work for you, here are the eagle board and schematic files. If you do not have the free eagle layout editor, you can get it from the dowmload links on this site. You can edit these files with this version of Eagle to make the design more specific of your application.

MP

ICL7107_Files.zip

 

[Kasamiko]

Thanks for the file MP..