Most analog meters are actually current driven - a current is needed to deflect the pointer full scale. They can be lots of different values. There are ones that can take several amperes to swing the pointer as they have internal shunts.
On the other hand there are many that are rated in microamps for the intent that they draw as little power as possible from the devices under test. Some are 1mA, 500µA, 200µA, 100µA, and the ubiquitous 50µA frequently used in analog VOMs. There are even 20, 25, 30 µA and even down to 10µA. Been collecting a bunch of different ratings and have things from 20A to the mere 10µA, and even some that can do ±30µA.
I thought I finally sorta completed my possible collection of meters by getting a meter that had a scale of a whole 5µA! Holy crap... Alas nope, got my hopes too high. That meter turned out to be 50µA and probably depended on an amplifier to need just 5µA to hit full scale.
So ... do 5µA meters exist? Are there anything lower? What's the lowest available full scale current reading?
Yes, digital meters have now gotten way past these but just wondering about these mechanical meters...
On the other hand there are many that are rated in microamps for the intent that they draw as little power as possible from the devices under test. Some are 1mA, 500µA, 200µA, 100µA, and the ubiquitous 50µA frequently used in analog VOMs. There are even 20, 25, 30 µA and even down to 10µA. Been collecting a bunch of different ratings and have things from 20A to the mere 10µA, and even some that can do ±30µA.
I thought I finally sorta completed my possible collection of meters by getting a meter that had a scale of a whole 5µA! Holy crap... Alas nope, got my hopes too high. That meter turned out to be 50µA and probably depended on an amplifier to need just 5µA to hit full scale.
So ... do 5µA meters exist? Are there anything lower? What's the lowest available full scale current reading?
Yes, digital meters have now gotten way past these but just wondering about these mechanical meters...
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