ICL7106 schematics from datasheet, mains voltage and higher?

[dds]

Okay, here is the schematics http://www.electroniq.net/files/other/icl7106.jpg, if I want to measure mains voltage AC, (230 V in Europe ) what steps are necessary to redesign this schematics? Voltage divider network?

Thanks!

[digsys]

Unless you can guarantee that the display is totally isolated from "the outside world", you should definitely use some form of isolation.
The simplest would be a small AC/AC transformer ie 230VAC > 5VAC
Is this part of equipment? User accessible? Knowing what you are trying to achieve would help.

[dds]

hi,

It's an simple voltmeter.

[mariush]

Read the datasheet, it contains all you need to know about how to set it up : http://www.intersil.com/content/dam/Intersil/documents/fn30/fn3082.pdf

the ICL7106 is in two variants, one which drives lcd segments and one which drives LED segments... be careful which one you get.

The LED segment version may work with 5v but it's designed to work with 9v ,  or with -5v and 5v (so 10v in total) and can also run at something like 12 v (absolute maximum permitted is 15v)  - it should be isolated from the rest of the system (power it from a separate power supply (transformer + rectifier+capacitors or a tiny switching power supply)

The datasheet also mentions some applications notes on one of the pages, one of them is AN046  Building a Battery Operated Auto Ranging DVM with the ICL7106 : http://www.intersil.com/content/dam/Intersil/documents/an04/an046.pdf
The appnote has the schematic for autoranging from 200mV to 200v if you want take full use of the 3 1/2 digits, otherwise you could just say 250v = 250mV and use only 3 digits.

[PA0PBZ]

the ICL7106 is in two variants, one which drives lcd segments and one which drives LED segments... be careful which one you get.

Not really, there is an ICL7106 for LCD and an ICL7107 for LED, but still not enough difference not to be careful 

[dds]

Thanks guys!

I've found this datasheet too, http://www.intersil.com/content/dam/Intersil/documents/fn30/fn3082.pdf
which has a schematic (figure 21) for AC to DC converter. Now I have totally naive newbie question about this figure: How could this Op-amp (CA3140) together with  100 kilo ohm resistor  survive let's say : 500 Volts AC?

[Bored@Work]

It can't, and they don't claim it will.

[digsys]

Now I have totally naive newbie question about this figure: How could this Op-amp (CA3140) together with  100 kilo ohm resistor  survive let's say : 500 Volts AC?

It CAN'T :-)  As I said, you HAVE to use a step-down transformer to 1/ Isolate the mains for safety 2/ obtain a safe working voltage