Digital Voltmeter!! on Breadboard

[remon7]

What is the Voltage your Measuring?

Without a Voltage Divider on the Input, Maximum voltage measurement may only be 0.199 Volts.
(199 Millivolts.)

3volts chemelec about my measuring volts. also what do u mean voltage divider ?? !!! i did not get you ..

 

[remon7]

No, initially make the measured voltage ZERO by shorting the inputs. No voltage to the + and - inputs. Attempt to read 000 first.

yeah its zero ,,Then ................

 

[KeepItSimpleStupid]

And you read these wacky voltages?

 

[remon7]

First digit !!! its not working well !!!!

 

[KeepItSimpleStupid]

The small grren cap and resistor in this https://www.electro-tech-online.com...256018220746_5471273230887772772_n-jpg.86470/ pic doesn't go anywhere.

 

[KeepItSimpleStupid]

Check your bread board. The two outer rows on each side are really 4 disconnected rows on your board, I believe. The larger "white space" divides or breaks the continuity of the rows.

e.g. The green vertical wire on the left of the pic I referenced is NOT connected to the two short horizontal green and browns that are cut off in the pic near the top of the page.

Note: EDIT

 

[remon7]

And you read these wacky voltages?

wacky means ???

 

[remon7]

yeah its zero ,,Then ................

i have checked about shorting input ,,but there is no 000 results !!!

 

[remon7]

No it needs to be negative 5 volts, thats what the 7660 chip is for.
You must fix this for it to work!!!

Yeah now its working but display showing me several random number. when i tried measure voltage about 3volts then it showed me 1 in left LED and Right LED turn off. Even in first LED is connected with IC about a, b, c, d ,e ,f ,g led. but working only b and c . sometimes g. bc connected with IC 19 number pin.

 

[4pyros]

Are you getting the negative supply voltage?

 

[remon7]

ok i am really confused which diagram should i follow ?

 

[DerStrom8]

ok i am really confused which diagram should i follow ?

Remind me, are you using the 7106 or the 7107?

 

[remon7]

I am using ICL7107 ,,,ICL7106 its not available there
.....Derstrom8

 

[remon7]

Remind me, are you using the 7106 or the 7107?

I have ICL7107

 

[DerStrom8]

Then I suggest you follow the schematic for the one that calls for the 7107

 

[remon7]

but there is not pin for negative part .............

 

[remon7]

Then I suggest you follow the schematic for the one that calls for the 7107

But you Told me Negative part is essential for this circuit ....

 

[remon7]

another question is how could i realize that my 7 segment display is common cathode or common anode ? Even in two display has no company or model name. maybe names are removed from display back side.

 

[DerStrom8]

But you Told me Negative part is essential for this circuit ....

Hmm, you're right. When I said to use a -5v display I was repeating what someone else had said--I had not looked at the schematic yet. Looking at both of them, I do not see a -5v supply in either one....? I wonder why someone mentioned needing -5v?

another question is how could i realize that my 7 segment display is common cathode or common anode ? Even in two display has no company or model name. maybe names are removed from display back side.

You should have mentioned that when I asked what components you were using. That's why I was asking for an EXACT list of what you had. However, if your display is showing any numbers at all, then chances are you have the correct type (CA or CC). However, you MUST check your wiring connections. If you cannot find a part number for your 7-segment display, you will probably have to buy one that matches the one in the schematic, or at least one that has the same pinout (and the same type).

 

[KeepItSimpleStupid]

A 1 in the left most digit only is surely a sign of overload.

Voltage too big. ground loops or attenuator resistances wrong.