Hello..can anybody help me about making an AC/DC LED Display voltmeter..
Or can anybody give me a site having this project.
I've researched a DC LED Display Voltmeter in this link
http://www.electronics-lab.com/proje...014/index.html
..is there anyone have a schematic modification in this circuit for measuring AC.?.Please..I need your help ASAP!!
Thanks!!!

 

you need ADC to measure DC voltage (in AC you need rectification) and write a MCU software to correspond to actual voltage compared to ADC binary output

 

Tnx...
but, is there a possibilty that you can modify the circuit without using MCU when measuring AC voltages?

 

You just need a rectifier, and calibrate the meter to read correctly for a sinewave input (as normal multimeters do). Even better would be a true-RMS converter, so it reads correctly for any shape signal - but these are somewhat more complicated and expensive.

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PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

use CA3162E and CA3161E if you don't want microcontroller

 

The DVM project mentioned uses the Intersil/Maxim ICL7107 IC.

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Uncle $crooge

 

Tanks a lot!! Are these IC's CA3162E and CA3161E can able to read AC voltages? I looked at their datasheets and I found that the maximum voltage range is only 999mV, how can I modify this so it can support a maximum voltage range greater than 999mV?.

 

All multimrter IC's measure DC. You add a rectifier to their input to measure AC.

They all measure a low voltage. You add a voltage divider with resistors to measure higher voltages.

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Uncle $crooge

 

as Nigel said, you need rectifier. to measure higher than 999mV, say 999V, use voltage divider resistor 332,667 ohms connected in series with a 333 ohms resistor. voltage drop on 333 ohms is 0-999mV while on the other resistor its 0-999,000mV

 

Here is a chip that converts RMS values to DC for you:

http://www.rapidonline.com/productin...moduleno=35606

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Angry!? I'm absolutely electrolytic!

Will have to make do with myspace now I guess...

 

thnx guys..it helps a lot!
one problem left on my project is the rectifier circuit design. Is this circuit suitable enough for my project?

or there are other rectifier circuit you can suggest?
Thnx again..God Bless You all!

 

by the ways, I want to know what particular value of each parts in the rectifier circuit will I use. Also, I want to calibrate it to 0-220 VAC inputs or possibly higher than that. Thnx!

 

The simple rectifier circuit will not measue AC below about 0.5V and will have an error measuring below about 5VAC.
The circuit will need at least one attenuator at its output made with a high voltage resistor and another resistor. The attenuator can contain a trimpot for calibration.

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Uncle $crooge

 

im back again,

pls help me how to short circuit the input (0V) in order to adjust the display to exactly 0..

heres the circuit..[IMG][/IMG]

 

You might not be able to adjust the display to exactly 0 with that old circuit. The many LEDs cause the IC to get hot inside and the heat changes its reading. Modern multimeters use a very low current LCD display so that their IC does not get hot inside.

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Uncle $crooge