Hi, i was working with the following project http://home.scarlet.be/johnstaybank/dvm_3_digit.htm which is a voltmeter with 3 seven segment display interfase. But i found the ICs CA3161E and CA3162E are obsolete. Is there any equivalent replacement for both?.

 

You might like the ICL7107 better - www.intersil.com/data/fn/fn3082.pdf

Here is a voltmeter project using one - http://electronics-diy.com/ICL7107_volt_meter.php

Mouser carries them for $12.16.

 

I didn't check your link, but the most common 3x7 segment DVM's are made based on Intersil ICL7107 chip. Perfect for a cheap and fairly accurate DVM. You might need to follow the diagram in their datasheet though.

 

Thanks for the advice on using the ICL7107. I made one (voltmeter) a couple of months ago using the schematic on the website cited at electronics-diy.

But i particulary liked the version with CA3161 and CA3162 because it could be modified to be an ammeter with very few components as noted on (Sam's electronics http://web.archive.org/web/20080112...~athsam/digital_volt_and_ambere_meter_eng.htm) . I found that an ammeter could be made with the 7107 as seen here http://electronics-diy.com/ICL7107_digital_ammeter.php, but my classmates told me the schematic is wrong. I haven't tried but does that schematic seems wrong?
And by the way Isn't there any way to find both outdated chips?.

 

There is. You can always get lucky and find them still offered by less mainstream electronic suppliers like Hosfelt Electronics or even Jameco (Jameco is getting up to a critical size, where the old stuff seems to fade away). Searching for surplus electronics stores can find all kinds of old IC's

There are also warehouse operations that stock literally any old linear or digital IC. The problem is that you have to bid on lots, and the minimum seems to be $500.

Here is a link to one of them - http://www.core-ic.com/catalog/I/I-121sum.htm

 

Hi,

I found that an ammeter could be made with the 7107 as seen here http://electronics-diy.com/ICL7107_digital_ammeter.php, but my classmates told me the schematic is wrong. I haven't tried but does that schematic seems wrong?

Your classmates are wrong, not the schematic.
The CA3161/2 is inferior to the ICL7107 in several ways. It has got half the resolution, less input protection and it tend to drift for a good while after turn on.

 

It is a fact that newer IC's are designed for better performance. Otherwise why would we upgrade a Pentium to Quad core rather than going back to a 486?

I have built DVM's using ICL7107 and it is accurate if you calibrate it well. And any DVM IC can be modified to become an ammeter if it allows calibration. An no manufacturer wouldnt produce one without that function.

 

Sorry to pull down a senior member soren, but the 7660 bit of the diagram is wrong
pins 3 and 5 are reversed, for the proper function

your comment " Your classmates are wrong, not the schematic ", is wrong

Rab

 

In two years, maybe he had time to change that...!

 

thank you atferrari

bit insensitive to mention it, >>> Sorry

Rab