FET voltmeter sought

[Peter Percival]

Suppose a fellow wished to buy a high input impedence voltmeter rather
accurate for low voltages (< 10v, say) but not expensive. Any
recommendations?

 

[Reinhard Zwirner]

Peter Percival schrieb:

Suppose a fellow wished to buy a high input impedence voltmeter
rather accurate for low voltages (< 10v, say) but not expensive. Any
recommendations?

What do you mean with "high"? Digital multimeters normally have an
input impedance of 10 MOhms; the lowest measuring range is 0.2 volts.

Best regards

Reinhard

 

[Peter Percival]

Reinhard Zwirner wrote:

Peter Percival schrieb:
Suppose a fellow wished to buy a high input impedence voltmeter
rather accurate for low voltages (< 10v, say) but not expensive. Any
recommendations?

What do you mean with "high"? Digital multimeters normally have an
input impedance of 10 MOhms; the lowest measuring range is 0.2 volts.

50 Mohms down to 0.01 volts. Is that too much to ask?

Best regards

Reinhard

 

[Phil Hobbs]

On 03/14/2016 08:40 AM, Peter Percival wrote:

Reinhard Zwirner wrote:
Peter Percival schrieb:
Suppose a fellow wished to buy a high input impedence voltmeter
rather accurate for low voltages (< 10v, say) but not expensive. Any
recommendations?

What do you mean with "high"? Digital multimeters normally have an
input impedance of 10 MOhms; the lowest measuring range is 0.2 volts.

50 Mohms down to 0.01 volts. Is that too much to ask?

A 50 M precision series resistor (probably a series combination),
measuring on the microamp range. You have 1 pA resolution there, which
is 100 uV. You do have to watch the burden voltage, of course.

Cheers

Phil

 

[Peter Percival]

Phil Hobbs wrote:

On 03/14/2016 08:40 AM, Peter Percival wrote:
Reinhard Zwirner wrote:
Peter Percival schrieb:
Suppose a fellow wished to buy a high input impedence voltmeter
rather accurate for low voltages (< 10v, say) but not expensive. Any
recommendations?

What do you mean with "high"? Digital multimeters normally have an
input impedance of 10 MOhms; the lowest measuring range is 0.2 volts.

50 Mohms down to 0.01 volts. Is that too much to ask?


A 50 M precision series resistor (probably a series combination),
measuring on the microamp range. You have 1 pA resolution there, which
is 100 uV. You do have to watch the burden voltage, of course.

Cheers

Phil

Thank you.

 

[JW]

On Sat, 12 Mar 2016 15:53:37 +0000 Peter Percival
<peterxpercival@hotmail.com> wrote in Message id:
<nc1e25$eli$2@news.albasani.net>:

Suppose a fellow wished to buy a high input impedence voltmeter rather
accurate for low voltages (< 10v, say) but not expensive. Any
recommendations?

If you want fairly cheap:
HP 3478A has an input impedance of >100Gohm on it's 3VDC or less ranges.
HP 3456A has an input impedance of >100Gohm on it's 10VDC or less ranges,
but size is a bit large.

 

[amdx]

On 3/14/2016 7:40 AM, Peter Percival wrote:

Reinhard Zwirner wrote:
Peter Percival schrieb:
Suppose a fellow wished to buy a high input impedence voltmeter
rather accurate for low voltages (< 10v, say) but not expensive. Any
recommendations?

What do you mean with "high"? Digital multimeters normally have an
input impedance of 10 MOhms; the lowest measuring range is 0.2 volts.

50 Mohms down to 0.01 volts. Is that too much to ask?

Best regards

Reinhard

You could put a 40M resistor in series and divide the reading by 5.
0.002V x 5 = 0.01V So, I guess you would need a 4-1/2 digit multi meter.
Or is that 3-1/2?

Mikek