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4 votes
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How to Read Unipolar Square Waves on TRMS Multimeter

262V peak unipolar (0V/262V) square wave will have an RMS value of 262/\$\sqrt{2}\$ = 185V. However the meter may actually be AC-coupling the input and measuring the RMS value of that. So you would ...
Spehro Pefhany's user avatar
4 votes

Using 50 Ω coax cable instead of passive probe

For a good balance of input impedance and capacitive loading, you can use 50 ohm termination and a series resistor at source end. For example 950 Ω resistor gives 1:20 attenuation and a consistent 1 ...
jpa's user avatar
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1 vote

Oscilloscope: when to use coaxial instead of probes?

The cable for an oscilloscope probe (connected to the a high impedance oscilloscope input) is (generally) not a standard coax cable. If it were, say, a standard 50 \$\Omega\$ coax cable, then when a ...
Math Keeps Me Busy's user avatar
3 votes

Using 50 Ω coax cable instead of passive probe

A passive probe is more than just a 9 MΩ resistor and a piece of coax. First of all, since both the input of the scope and the coax have significant capacitance, there is a compensating capacitor in ...
Dave Tweed's user avatar
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8 votes
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Using 50 Ω coax cable instead of passive probe

Yes, you can do it. However.. the capacitive loading is fairly high on small coax cable. Maybe ~100pF per m for 1.13mm⌀ cable. So if you connect it to anything with fast-ish edges it will load the ...
Spehro Pefhany's user avatar
3 votes

Using 50 Ω coax cable instead of passive probe

The DC resistance of a coax cable is usually somewhere between 0 and 5 Ohms per 1000 meter. So yes, when you configure your scope to high input impedance, your proposed setup works out fine.
Stefan Wyss's user avatar
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1 vote

How to measure multiple resistances with Arduino Uno, without one measurement influencing the other?

Use the comparator peripheral and a big cap. Time how long it take a step to charge or discharge with the timer module.
Scott Seidman's user avatar
2 votes

How to measure multiple resistances with Arduino Uno, without one measurement influencing the other?

Saying you have an Arduino means nothing, like saying you have a car and ask why it performs poorly when driving on F1 track or sand dunes, but not revealing the car type or model. Fortunately most ...
Justme's user avatar
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1 vote

How to measure multiple resistances with Arduino Uno, without one measurement influencing the other?

Generally it’s better to keep the impedances at analog input pins no higher than a few thousand ohms. Otherwise there will be undesirable effects from leakage and from the relatively low input ...
Spehro Pefhany's user avatar
0 votes

What is the real resolution of my voltage measurement when I use only some of the range of of the ADCchannel

The question isn't what is the real resolution it's what the noise floor is. If you have one millivolt of noise then for a 30uV count you'll have ~32 bits that are noisy which is 2^5 or 5 bits that ...
Voltage Spike's user avatar
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0 votes

Measurement of output current of a photodiode

In addition to the great suggestions by The Photon, raw datalogging can be done with something like a Picoscope or Analog Discovery. These also include all the nice math and measure functions you'd ...
Photonic's user avatar

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