Led display Digital Voltmeter question

[mahalkoh]

ei,guys i need your help about this digital voltmeter using ICL7106. can u help me,we need a circuit diagram for it...thankz

 

[ante1]

mahalkoh,

Welcome to this forum.
Here is the datasheet for ICL7106: http://www.intersil.com/data/fn/fn3082.pdf

 

[charliecuattro]

thanks MP

a isolated dc-dc converter might work??
somebody can helpme with a low cost circuit dc-dc isolated??
i edit the board file from eagle and added:
on-off-on swch
grid ac led
inverter led
the bridge for ac readings
becouse dc-ac inverters usually have big battery banks , will be nice to power itself the voltmeter.
as soon i finish i will post here
thanks

 

[MP1]

Charlie,
I am having a problem envisioning what you mean. If your power source and your measured voltage will not interact with each other, the circuit will work. Otherwise, there is a problem. Can you post what you propose for comments?

MP

 

[charliecuattro]

hi,
i have a dc-ac inverter 3kw 110v from 12v battery bank.
i would like to monitor the battery voltage, but i dont want to use 9v
alkaline battery nor 110ac power supply for power the voltmeter.
becouse i can not feed the vmeter from same source i'm monitoring,
i want to use a circuit to be able to do that , a dc-dc converter or any suggestions.
9v do not last enough for always on situation.
thanks

 

[Dido]

I`m planing to do this project I read your discusses : and even now I can`t understand if the PCB given here in the article is OK I hope so beause I`ve already etched it.

 

[ante1]

Charlie,

You have to use a DC-DC step down circuit with isolation transformer.

 

[MP1]

Dido,
The final discussion was in the feedback area. I will ask mixos to move it over to this one so that they are easier to find.
In the mean time, I recommend you look at the posts. I posted a pcb layout in eagle format in that forum.

MP

 

[charliecuattro]

hi,
i already contacted www.beta-dyne.com who make a 9v to 5v dc converter 2watts , 400 ma isolated and they are on their way .
As soon i have them i will post results and my modified board layout.
becouse mostly dc-ac inverters use 12v or 24 v configurations, i will
use 9v to 5v beocuse at 9 v the dvm will work besides the inverter who stop working at 10.7 v. i will feed the dc-dc from lm317 to220 1.5 amp variable regulator at 9.2 volts , so does not matter if is 12v or 24 volts battery bank .this is important becouse i built dc ac inverter up tp 10kw for 110 or 220 vac , and that will be a nice feature

View attachment 35845

 

[Kasamiko]

I've successfully constructed this project and set the range to 20VDC by using a 100k input resistor..I connected it to my power supply LM317 but notice that my last digit wont lock, let say i'll set the voltage output to 3.6 vdc, my display says 3.61, 3.63, 3.65....dirty pots?

 

[audioguru2]

Hi Rhonn,
You are trusting the stability of your components:
1) How much do the values of you project's and your LM317's resistors change as they warm up?
2) How much does the voltage references in the IC for this project or in your LM317 change as they warm up?
Your IC for this project is driving many LEDs so will not remain cold.

My purchased digital meters are stable maybe because their IC is driving a very low current LCD display, and/or maybe because their manufacturers used very stable 1% or better metal-film resistors.

Most meters are calibrated after a long warm up period. See if yours becomes stable after both it and your LM317 have been turned-on for about 1/2 hour.

 

[duhaas88]

I have been reading these posts, and I must say there are some very bright individuals in here

anyways, I would like to use this cIrcuit to measure the voltage of a power supply output, however it is 0-25.2 VAC not DC, is there a mod I can implement that will allow this?? I will use a separate power supply for the + and - 5v. I saw in the spec sheet in figure 21 that a AC to DC convertor with the ICL7106 can be used?? Can i simply implement that circuit??

I'm a newbie at this stuff, so please forgive my ignorance!!!

 

[ante1]

You need an instrument rectifier.

 

[duhaas88]

You need an instrument rectifier.

Ante,
Was this in response to my questions??
Can you be more specific?? Is this a costly solution? Hard to implement? LIke I said before I"m a newbie

Duhaas88

 

[MP1]

Look for the thread on the digital voltmeter corrections. A schematic was posted showing how to convert it to AC/DC input. It was posted here:
http://www.electronics-lab.com/forum/index.php?board=13;action=display;threadid=1516

MP

 

[ante1]

This is an instrument rectifier. It

 

[audioguru2]

Hi Ante,
Your full-wave rectifier circuit works fine at low frequencies, I have used it many times. Its "full-wave" becomes assymetrical above about 2KHz, unless you use a wide bandwidth opamp like a TL074, which rectifies well up to about 25KHz in this circuit.
The TL074 has FET inputs so RV2 is unecessary (input pin 10 connects directly to ground), but an offset voltage adjustment is needed with any opamp for very low-level inputs.

 

[ante1]

Hi Audioguru,

Well, since the girl wants to measure the output voltage from a power supply I think it

 

[Zwieke]

Just to be sure:
If I change the circuit to the one I've attached It would measure Current instead of Voltage right?

Edit: I need it to measure 0-3A

View attachment 36268

 

[Zwieke]

anyone?