Digital Voltmeter!! on Breadboard

remon7 · May 23, 2014

Now i am working on Digital Voltmeter. Already i bought all components for Digital voltmeter. I am using 7 segment display. In 7 segment display.. i am not understand about DP..also i mention in my attachments also i dont have 470n capacitor but i have 47uf capacitor , can i use it there ?

DerStrom8 · May 23, 2014

Hello remon7,

"DP" stands for "Decimal Point". Connect that pin to ground (through a resistor) to light the "dot".

There is a huge difference between 470nF (0.47uF) and 47uF (it is off by two powers of 10). You will need to find something at least in the range of 470nF.

Regards,
Matt

remon7 · May 23, 2014

is it DP ?

DerStrom8 · May 23, 2014

remon7 said:
is it DP ?

I suggest you google the part number and find the datasheet. It should have the pinout of the device.

Regards

remon7 · May 23, 2014

first things that i use 4.5volts and mention that i did not use 470uf capacitor . without this cap i tried to run , but its not working. i dont know whats happen ? how can i check whole circuit ? means checking all components?

remon7 · May 23, 2014

i want to check whole circuit every components .....

alec_t · May 23, 2014

its not working. i dont know whats happen ?

If you don't use the specified components in the right way of course it won't work!
You can't check all the components (individually) unless you know how each component should perform or what its properties should be. That requires reading the relevant datasheets. Google the part numbers and download the (free) datasheets.

Reloadron · May 23, 2014

This is a link to your datasheet for the ICL7107 chip you are using.

This is a link to your displays you are using.

Use the data sheets and you will understand, as pointed out, why it is very important to use the parts called out in the drawing, especially the capacitor values. The data sheet for the actual voltmeter chip has some very good examples.

Ron

audioguru · May 23, 2014

I think your tangle of long wires and the many rows of contacts on the breadboard will pickup all kinds of interference. A pcb should be used.
The ICL7107 voltmeter IC is sensitive to interference.

tunedwolf · May 23, 2014

audioguru said:
I think your tangle of long wires and the many rows of contacts on the breadboard will pickup all kinds of interference. A pcb should be used.
The ICL7107 voltmeter IC is sensitive to interference.

I agree, the ICL devices are very twitchy if the board layout is poor.

remon7 · May 24, 2014

Yeah finally i have finished my digital voltmeter project, and stuck me. when i plug 4.5volts then it showed me weird number symbol. also when i tried to measure a battery volts then digit symbol also changing, but it does not make any sense , As well as its true that its working, but i could not get where main problem.... ok number 1pic when i used battery for measure. number 2 plug current 4.5volt . without measurements.....normal .. I used ICL7107 somewhere i noticed ICL7106 using for same voltmeter ...so i am using ICL7107. here ICL7106 is not available ..

DerStrom8 · May 24, 2014

Check your wiring and the datasheet for your display. Are you SURE you used the EXACT parts shown in the schematic? Judging by your previous attempts, I would lean towards "no", in which case of course it won't work. If you did, though, double-check the wiring.

remon7 · May 24, 2014

in picture there mention ICL 7106 and ICL 7107. But i am using ICL 7107. any problem ?

DerStrom8 · May 24, 2014

The 7106 is designed to drive an LCD display, whereas the 7107 is designed to drive an LED display. How about the LED display part numbers? Are they the same as shown in the schematic?

Could you please post a schematic of YOUR exact setup, with the EXACT part numbers that you are using on your breadboard?

remon7 · May 24, 2014

i tried to follow new idea about voltmeter. finally its failed again. in 7 segment display nothing shows me.

remon7 · May 24, 2014

its diagram

remon7 · May 24, 2014

now i have connected with source but reply is just turn on 7segment display dot light. it does not shows any digit. also i tried to measure battery volts. no output

DerStrom8 · May 24, 2014

Photographs of your setup with messy wiring really don't help much, I'm afraid. I need you to tell me EXACTLY what components you used, and compare it with the ones shown in the original schematic.

Also, try to neaten up your wiring. Chances are that may be causing some of your issues--it's too confusing to follow, and perhaps there's just a single wire out of place.

4pyros · May 25, 2014

remon7 said:
first things that i use 4.5volts and mention that i did not use 470uf capacitor . without this cap i tried to run , but its not working. i dont know whats happen ? how can i check whole circuit ? means checking all components?

You keep jumping all around and never really answer the questions we ask. If you slow down maybe we can help but you keep changing things.
Did you get the right cap?
Can you neaten up your wiring?
May be just hook up the LSB digit for now untill you can get the chip running.

audioguru · May 25, 2014

Why don't you use the schematic shown in the datasheet printed by the IC manufacturer instead of using a copy from somewhere that might have errors on it??

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