43
votes
100 MHz probe and 200 MHz probe show very different waveform on 1 MHz signal
The signal under test is 1MHz, and as far as I can see, both probes are showing that signal correctly.
What you are looking to see on the edges, is less than 20ns. A signal with a period of 20ns has a ...
- 1,938
42
votes
Accepted
100 MHz probe and 200 MHz probe show very different waveform on 1 MHz signal
A 1 MHz sine wave is not the same as a 1 MHz square wave - the most important part of what you're measuring and interested in here is actually the "edge rate", or the rise and fall times.
...
- 2,438
20
votes
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Which wire is hot?
Which wire is hot doesn't matter. According to the schematics in the service manual, both wires from the power plug go straight into the transformer (via the fuse and switch.) If hot/neutral ...
- 73.1k
13
votes
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Just inherited a digital phosphor oscilloscope and trying to figure out why the sine wave is doubled
The trigger module is likely having trouble with a slightly noisy waveform. OP's waveform display is slightly out of focus, so it is difficult to see how much high frequency noise is present on that ...
- 27k
11
votes
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Dangers of floating oscilloscope
I believe the situation in the video is such that a scope is used for debugging the unisolated mains side of a fly-back type switch mode power supply.
As no point in the unisolated side is at ground ...
- 165k
11
votes
Accepted
Caps vs. no caps = the same noise?
The way you probe the supply rail is not the preferred way because the probe and the ground clip form a large enough loop to pick up noise, quite possibly the noise you see on the scope display.
Try ...
- 38.1k
10
votes
Trying to get the full potential of my 100 MHz oscilloscope
The meaning of bandwidth here is the -3dB frequency. This is basically the frequency at which the output amplitude is ~71% of the input signal's amplitude (-3dB power loss corresponds to half the ...
- 38.1k
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 ...
8
votes
Accepted
How is switching of measurement ranges in instruments, like oscilloscopes, realized nowadays?
Small sealed telecom style relays are frequently used. They have many advantages over solid-state switching (low leakage, low 'on' resistance, low capacitance, high voltage capability) and are ...
7
votes
Accepted
Trying to get the full potential of my 100 MHz oscilloscope
If you purchase a \$100 \space \mathrm{MHz}\$ oscilloscope with the intention of observing a \$100 \space \mathrm{MHz}\$ signal, you will encounter significant measurement error.
The bandwidth \$BW\$, ...
- 3,365
7
votes
How can I measure the speed of sound with an oscilloscope and ultrasonic sensor? (Currently getting low value.)
Your approach is not taking into account the very narrow bandwidth of the transducers. @jsotola's point is that it takes some time for the oscillations to build up in the transmitter, and a similar ...
- 177k
6
votes
Why does an AC Voltage reading on a DMM decrease as the frequency is increased?
On a cheap meter the signal is AC-coupled, then rectified using a precision rectifier and then low-pass filtered yielding an average voltage, which is then (for display) (effectively) multiplied by ~1....
6
votes
Why does an AC Voltage reading on a DMM decrease as the frequency is increased?
The oscilliscope is designed to display a wide range of frequencies accurately - from DC to 50 MHz or more, while a common DMM will usually only cover a much smaller frequency range - mine shows the ...
- 60.2k
6
votes
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Is there anyway to estimate the time average power without knowing the power factor?
P = Vrms · Irms · cos(ϕ)
The above is true theoretically for sinewaves with no harmonics, no non-linearities and an ability to measure the phase angle between voltage and current. In other words it'...
- 467k
5
votes
Accepted
Square wave of oscilloscope for RC circuit
That in-scope square wave generator will be fine.
Measure its output resistance, as that will add to the effective value of any series R you are using with your C. Do that by loading it with a ...
- 171k
5
votes
Crystal Oscillator Waveform
It's not that unusual really. Depending on what you expect of course.
It's not the chip that alters the signal, rather it's the crystal. Or both, depending on viewpoint.
The oscillator amplifier ...
- 165k
5
votes
Crystal Oscillator Waveform
I am assuming that your question is about the square shape of the second waveform. This is perfectly normal. There is an amplifier between the 2 oscillator pins (for eg., take a look at figure 2 in ...
- 4,227
5
votes
How can I measure the speed of sound with an oscilloscope and ultrasonic sensor? (Currently getting low value.)
how to measure the speed of sound with oscilloscope and ultrasonic
sensor? (Currently getting low value)
Time is required for these narrow-bandwidth transducers to build amplitude to full - both ...
- 27k
4
votes
Solutions for holding oscilloscope probes (and freeing up hands)
Amateurs. I present you THE holder
- 3,492
4
votes
Establishing communication between laptop and an oscilloscope
This kind of Tek oscilloscope has two different kinds of USB connector. You need the "device port"; alternatively, consider using ethernet.
Quotes and image from manual
2: Device Port &...
- 15.2k
4
votes
Accepted
Establishing communication between laptop and an oscilloscope
So you used a cable with Type-A USB plugs on both ends.
Please do something with the cable so you never use it again.
Such cables should not exist, as they allow two hosts and their power supplies to ...
- 165k
4
votes
Accepted
How to connect PE lead of oscilloscope?
You connect the protective earth from the oscilloscope to the protective earth of the outlets in your home/laboratory.
The USB port powering the scope doesn't have protective earth. An oscilloscope ...
- 73.1k
4
votes
Accepted
Old oscilloscope has its plastic screen slightly shifted, is it safe to use?
It will be fine. The acual CRT is a sealed glass tube so you don't get exposed to any of the high-voltage stuff.
It would be worth taking the cover off and fixing it in place so the grid doesn't move ...
- 178k
4
votes
Signal gets amplified in oscilloscope
Set the channel to 10x and set the scope probe to 10x. They should always match.
It's almost always better to use 10x because the bandwidth will be better. The input-referred noise will be more ...
4
votes
Just inherited a digital phosphor oscilloscope and trying to figure out why the sine wave is doubled
The scope is triggering on both the rising edge and the falling edge of the sine wave zero-crossing point.
You need to adjust the trigger level knob (in the Trigger instrument cluster).
The Trigger ...
- 15k
4
votes
Accepted
Partially nice waveform on debugger pin
The SWD is a bi-directional half-duplex communication bus, so both the host and target can take turns and send data to the other party.
The sharp fast rising (or falling) edges happen when either the ...
- 165k
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 ...
- 9,021
4
votes
Accepted
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 ...
4
votes
Crystal Oscillator Waveform
A few possible explanations:
Loading Effects and Probing Issues:
Probing the circuit itself can introduce capacitance and even small inductance, which can cause waveform distortion. On the right ...
- 664
4
votes
How is switching of measurement ranges in instruments, like oscilloscopes, realized nowadays?
Reed Relays are still pretty good - if not the best - signal switches. With an extremely good ratio of Off/On impedance, they are much better than FET switches, as far as I know.
Their drawback is ...
- 22.8k
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