Block diagram of multi range ammeter

[johnkok017]

Someone can help me to solve this question? Describe the architecture of a multi range Ammeter by showing the block diagram, and circuit diagram of it.

tq ^^

 

[ericgibbs]

Someone can help me to solve this question? Describe the architecture of a multi range Ammeter by showing the block diagram, and circuit diagram of it.

tq ^^

hi,
This is a good starting link.

https://www.electronicsteacher.com/direct-current/dc-metering-circuits/ammeter-design.php

I Googled architecture of a multi range Ammeter lots of hits

 

[bountyhunter]

Someone can help me to solve this question? Describe the architecture of a multi range Ammeter by showing the block diagram, and circuit diagram of it.

tq ^^

An ammeter is simply a voltage meter reading the voltage drop across a resistor. You switch in different resistor values to get different current ranges.

 

[KeepItSimpleStupid]

Range plays a BIG role. I'll tell you from experience that a 0.01 mA to 100 mA full scale feedback ammeter is tough to design.

 

[johnkok017]

tq for you all

 

[WTP Pepper]

You are better using a DVM module rather than a conventional meter purely down to the series resistance the ammeter imposes on a cicuit.
I have seen many of my graduate engineers measuring small currents on microprocessor circuits when they are in low power mode. When they wake, the circuit resets as the series resistance of the ammeter causes enough voltage drop due to start up current to cause the micro to reset.
This can happen even using high end commercial FLUKE equipment.

It's all about knowing what you are measuring, using the correct equipment on the correct settings and was a large part of my Diploma in the '80s

 

[KeepItSimpleStupid]

Right. Try measuring the resistance or should I say conductance, of a piece of paper. I could.

There are different techniques for measuring pA, amps and hundreds of amps. Between 1 nd 100 mA and low voltages, there isn't much out there to use besides Agilent's and Keithley's Source Measure Units. There is nothing that will measure in an analog way 100 mA to 0.01 mA in 4 ranges, so I had to build it. Biasing was +-10V, it was 4 and 2 terminal, 4 quadrant, +-10V out and a V(open circuit) mode. This was a front end to a Lock-in. 0 to -1V bias was it's usual operating parameters. It also sported a clipping indicator. Autoranging was incorporated in the high level program.

Zero Check and Zero correct were problematic and never fixed, but the DC performance was secondary to the application. Ther main issue was that the IEEE-488 bus D/A converter didn't output exactly zero volts. The IOTech version of the same Keithley product supposedly did. They used a relay to output exactly zero bearing in mind thermal EMF's. I also left out all of the offset trimmers. Offsets were below a few uV anyway, but they really matter.

For fun and giggles, I added a +-50 mA suppression, but only if the bias was between +-5V.