Does anyone here has a schematic for digital ammeter. Thanks in advance.

 

Use a digital panel meter with a switch to connect the various shunts for each range

 

ljcox, tnx for a quick response. But what i need is an auto range one, it will be used to monitor the charging current in a battery charger ckt.

 

I don't see any need, a digital panel meter will read from 0-1999. If it's scaled to read 19.99A that's giving you 10mA resolution in 20A - which is far greater than you could possibly need for a battery charger.

If you don't need that large a charging current, scaling to 1.999A would give 1mA resolution in 2A.

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Thanks, Nigel... By the way, Do you have a simple/cheap ckt of a digital meter that I can build?

 

Try googling for icl7107 or icl7106, these are two common chips for digital meters. However, it's probably cheaper to buy a ready built display than to buy a chip and an LCD.

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

 

In my brief research of ICL7107 IC's, most sales places want aroun $12 for the IC itself, then you add on the external components which ranges anywhere from $2-$10, then add on the actual display which ranges anywhere from $2-$20 depending on the number of digits you need. So the approximate cost is about $28, give or take a few dollars.

A common replacement for the ICL7107 and ICL7106 are the NJU9202 and the NJU9201 respectively. Digikey sells these IC's for around $6, which provides some cost reduction.

Still, most panel meters are around $12-$15. So this option is definately worth taking a look at.

Here's a link to a recent topic about ammeters which should give you some good hints, if you should decide on going the ICL710X route.

http://www.electro-tech-online.com/v...111&highlight=

 

Thanks a lot guys! Such a great help... God bless!

 

i think this is what ur looking for mate i used this in my degree switch mode power suppy project it measures up to 5 amps in 10mA steps

R1=39k, R2=47ohm, R3=13k, R4=220ohm, R5=1.5k, R6=1M, R7=100k, R8=3.3k, R9=15ohm, R10=56ohm, R11=100ohm, RS=0.1ohm 3watt. R1= 1k trimmer, D1=1n4148, D2=1n914, C1,4,9=47nf, C2=220nf, C5=10nf, C6=100nf, C7=100pf, C8=680pf, C3=100uf 16V electr, C10=10uf 16V electro, Q1=2sc945, U1=ICL7107, U2=LM7805 5V regulator
This runs 4 '7 seg displays'

Attached Images

ammeter1.jpg (445.2 KB, 305 views)

 

.. :lol: :lol:
a couple of days more and it will be exactly 2 years :!: :lol:

Thanks anyway, may be useful to someone else1