56
votes
Accepted
CRT Oscilloscope - part of the plot is missing
The trace is perfectly fine.
On CRT oscilloscopes, the brightness of the trace depends (partly) on how fast the electron beam moves across the screen.
The horizontal speed is set by the sweep time. ...
- 73.1k
22
votes
CRT Oscilloscope - part of the plot is missing
No, nothing is missing.
If you turn up the sweep rate of the timebase you can probably see the rise/fall time of the low vs high transitions of the calibration signal. Turning up the intensity may ...
- 33.6k
18
votes
Accepted
What are the differences between a x1 and a x10 oscilloscope probe
The pro is that a 10x probe has 10x the input impedance so will interfere with the signal being measured less. The con is that it is reducing the voltage on your signal by 10x before it reaches the ...
- 57k
18
votes
Accepted
What is this oscilloscope accessory?
That's an attachment used when taking high frequency measurements. It minimizes the distance between the probe and ground. The little finger is your ground. Here is a similar attachment: https://...
- 1,159
16
votes
Good uses for 1:1 probe
Noise in oscilloscope front ends is quite high, maybe 1mVp-p.
Using the 1:1 probe lowers the input-referred noise floor by an order of magnitude. Still pretty crappy, but opens a few doors.
16
votes
Review request: DIY DC to 50MHz differential oscilloscope probe
After actually building the thing
I can finally answer my own question in hindsight. I've built the circuit as featured in the question, with a 1:10 attenuator.
Could I get away without ...
- 8,661
14
votes
Accepted
Why is an oscilloscope's Attenuation switch placed on the probe?
The reason for putting an attenutator at the probe is to reduce the loading presented by the probe to the circuit under test. For a high-impedance probe (most probes) the cable looks like a capacitor, ...
- 23k
14
votes
Why doesn't this DIY high-speed probe reflect signals?
The point of this probe is that the scope has its 50Ω termination enabled. Since the scope input impedance is matched to the cable, there is no reflection from the scope. Once the load side is matched,...
- 2,593
13
votes
Accepted
Why are oscilloscope input impedances so low?
I would say a combination of a few factors.
The input stages of an osciloscope are a difficult compromise. They need to be have a wide range of gains/attenutations, they need to be tolerant of user ...
- 23k
12
votes
CRT Oscilloscope - part of the plot is missing
The rise time of a fast square wave signal observed through a 60 MHz probe should be around 5 nanoseconds. This is too fast to be clearly visible with your current time base (1 ms/div?).
Set your ...
- 26k
11
votes
Accepted
High speed passive probe - contradiction between authors or different points of view?
For 100 MHz and slower probes, the wavelength of the signals in question is long enough that the cable doesn't really act like a transmission line and the probe tip pretty much directly 'sees' the ...
- 41.5k
11
votes
Accepted
Does this experiment show that Kirchhoff's Law hold when there's a changing magnetic field involved in a circuit?
The lumped component models to which KVL is applied are just that--models. Like all models, they are only accurate to the extent that they represent the relevant characteristics of the system they ...
- 3,454
11
votes
Why are oscilloscope input impedances so low?
A lot of things are the way they are because of history, and de facto standardisation.
A general purpose oscilloscope input is a difficult compromise between not loading the circuit, not being damaged ...
- 171k
10
votes
Accepted
Noise (capacitance-related?) in serial signal
So, I followed the advice given by the two kind people that commented... Here are the results.
Ali Chen indicated the slow edges can be attributed to the capacitance of the RCA cable; and "Anonymous" ...
- 427
10
votes
Good uses for 1:1 probe
Convenience. A 1:1 probe (or the x1 setting on a switchable x10 probe) will probably have slightly lower capacitance than a 50ohm coax of the same length, and also handy clips on signal and ground. It'...
- 171k
10
votes
CRT Oscilloscope - part of the plot is missing
What makes you think there should be a vertical part?
The vertical parts show the voltage. So let's say your top level is 1V, and bottom level is -1V, you will only see a vertical line if there is ...
- 595
10
votes
CRT Oscilloscope - part of the plot is missing
Look very closely at the rising edge of your third photograph, and you can faintly see the vertical trace. Since the width of the square wave is not perfectly stable, you can't see the falling edge.
...
- 60.8k
10
votes
Differential probe input impedance 1Meg, but 50ohm oscilloscope mode recommended
The probe itself is an active device which has input and output, each one with its characteristics (given in the manual):
Impedance matching, like with a standard signal generator with 50 Ohm output, ...
- 8,567
9
votes
How the low inductance of short ground clip probes prevents interference?
It doesn't prevent interference. It prevents ground lead impedance.
Simply imagine an inductor in series with your ground connection: that acts as a low-pass filter. So, high-speed currents can't be ...
- 98.3k
9
votes
Does the circuit troubleshooting tool used in 2001 A Space Odyssey exist in the real world?
The movie the tool is a visual prop to help the audience understand that they were analyzing a circuit. It has elements of real devices like continuity meters and board schematic view tools, but is ...
- 17.8k
9
votes
Accepted
Homemade high-voltage probe not dividing the voltage by proper amount
This meter claims to be \$ 20k\Omega\ per\ volt\$ when measuring DC voltage.
For AC voltages, ohms-per-volt is less (can't make out the value 3k/V? 5k/V?)
However, on its most-sensitive voltage ...
- 27k
8
votes
Accepted
Is it acceptable to use decoupling capacitor ground pad as ground for oscilloscope probe?
In general you want to minimize the loop area when probing fast signals. So, as a rule of thumb, you should select the ground connection that minimizes the loop area.
Now this is only in general. ...
- 6,177
8
votes
Accepted
Oscilloscope probe noise
Why and from where am I getting this unwanted 50mV peak to peak ripple
Start by thinking about 220 volts (if that is your AC supply running in your building). Because it runs in two wires where one ...
- 467k
8
votes
Accepted
My sourcemeter lets me do a four probe connection using banana connectors or tri-ax. What do the extra lines on the tri-ax do?
The triaxial cables are for low-current, high-precision measurements in the nanoamp range. From the 2450 datasheet:
The real-panel diagram shows how the conductors are connected. The second (middle) ...
- 22.3k
8
votes
Accepted
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 ...
7
votes
Accepted
Where to leave the test leads on a Fluke multimeter
As a long-suffering hobbyist happy to finally have a grown-up multimeter, I was surprised this wasn't more intuitive. I think I've worked out a decent way to wrap it:
Leads remain plugged into ...
- 258
7
votes
High speed passive probe - contradiction between authors or different points of view?
Indeed the Hiscocks document is quite clear, 9 M series resistance in probe, 1 M to ground in scope. Add capacitors in parallel so that for high frequencies the 10:1 ratio is maintained. That all ...
- 81.1k
7
votes
Oscilloscope: when to use coaxial instead of probes?
This is not about what is "better" or not. It is a question whether the source of signal has low enough impedance or not.
In many cases the oscilloscope probing is meant to be "non-invasive", and ...
- 41.9k
7
votes
Why are oscilloscope input impedances so low?
Actually, it is ridiculously high for a wideband input.
There is no practical connector or cable that actually has an impedance (from a transmission line view. Resistance, but for coaxial cablers, ...
- 3,135
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