57
votes
If a square wave has infinite bandwidth, how can we see it on an oscilloscope?
We can't. We see a bandlimited version. That's obvious for two reasons:
perfect square signals cannot physically exist, for changing a voltage within 0 time would require an infinite amount of power
...
- 98.3k
26
votes
If a square wave has infinite bandwidth, how can we see it on an oscilloscope?
You are correct that an ideal square wave needs an infinite bandwidth as it contains frequencies up to infinite frequencies.
But this is theory, ideal square waves do not exist in the real world as ...
- 81.2k
24
votes
Accepted
What does the radiation from an antenna look like?
This image:
Is just a drawing, it has no meaning. It does not represent the radiation pattern of an antenna in any way !
Basically all antennas radiate (and receive) the EM waves in all directions. ...
- 81.2k
24
votes
Accepted
What is causing this distortion of a pulse wave when recorded to a reel-to-reel tape?
Your original digital signal is bent out of shape because it has been high-pass filtered by the tape recorder.
Let's have a look at Korg Volca service manual and dig in the schematics, here is the ...
- 80.3k
23
votes
Accepted
Why is signal on XTAL1 and XTAL2 a sine wave (not square)?
This circuit is not a digital circuit. In fact, it is a fairly mathematically complicated non-linear analog circuit with automatic gain control with self-sustainable oscillation mode. It is called a "...
- 41.9k
22
votes
Accepted
Why is Zener avalanche noise saw tooth shaped?
Consider that you effectively have this:
simulate this circuit – Schematic created using CircuitLab
where C is the junction capacitance, plus any external capacitance (leads, breadboard, etc). ...
- 4,309
19
votes
How do you shift a square wave down?
There are several simple options.
Rail-to-rail op-amp
If you have a rail-to-rail op-amp, this can be done using four resistors as follows:
This will divide the signal down to 0-15V which is in the ...
- 68.8k
18
votes
If a square wave has infinite bandwidth, how can we see it on an oscilloscope?
The 'scope won't show a perfect squarewave and if you zoom in on the timebase you should be able to see the rising and falling edges with some slope on them. This will be most obvious on an analogue ...
- 178k
14
votes
Accepted
What units are kpts?
K for "thousand"
pts for "points".
The unit is thousands of points.
How would I convert that to a wavelength unit such as meters?
You can't. This is the maximum number of samples that can be ...
- 132k
12
votes
Accepted
Why IR remote waveform is a saw-tooth or am I measuring it wrong
From the TI LM358 datasheet, the maximum output slew rate of your op-amp is about 0.3 V/us:
Your scope trace shows the signal has a slope of about 3 V per 10 us, pretty well matching the datasheet ...
- 132k
12
votes
Accepted
Why does putting resistors between Vcc/SDA & Vcc/SCL in I2C result in a square wave?
I2C is a bus that uses open drain outputs. An open drain is like a switch connected between the output and ground. It will not work without pullup resistors because there is nothing to make it go high....
12
votes
What protocol is this waveform?
You have done excellent reverse-engineering.
Everything does point out to RS-485 physical interface with UART protocol and the bit rate is likely just standard 38400 bps based on the measurements of 3 ...
- 165k
10
votes
Accepted
How do you shift a square wave down?
How do you shift a square wave down?
Just an RC will do it: -
If fed with a sine wave (for the convenience of the attached picture), it will reproduce the sine wave at the output but with the DC ...
- 467k
10
votes
What are the waveforms of radio frequencies?
A modulated radio signal generally has a bandwidth which is a tiny fraction of its centre frequency. This means that any short stretch of signal will look essentially sinusoidal.
It's only when you ...
- 171k
9
votes
What does the radiation from an antenna look like?
It really depends on the kind of antenna. Google will probably answer this with pictures better than I will (Google "antenna radiation pattern").
You will distinguish in shape of radiation mainly 2 ...
- 221
9
votes
Why is signal on XTAL1 and XTAL2 a sine wave (not square)?
The crystal (+C1/C2) is a very narrow bandwidth resonator/filter.
Only the fundamental frequency can fit through it.
Sine waves are a single pure frequncy, So it is a sine wave.
Square waves are ...
- 5,433
9
votes
What is causing this distortion of a pulse wave when recorded to a reel-to-reel tape?
Magnetic recording is inherently differential; using an inductive pickup, one measures changes in the magnetic field rather than levels. This implies a rolloff at some frequency which will be ...
9
votes
Accepted
Is it possible to change Arduino Nano sine wave frequency without using PWM?
There's no (reasonable) way to do this without changing the code on the Arduino.
I have a few suggestions for you:
"DDS", AKA "Direct Digital Synthesis"
Some other answers have ...
- 1,439
8
votes
What is causing this distortion of a pulse wave when recorded to a reel-to-reel tape?
I had a quick look at the video, and didn't see an image of a waveform.
It is entirely possible that the waveform recorded in the video is just a distorted as your is, but that it still works.
Tape ...
- 73.1k
8
votes
Accepted
How to make this arbitrary waveform?
The reflection about the Y axis can be obtained by inverting one of the input signals but not the other. Look carefully at the summing junctions in the following circuit, noting how the first (top) ...
- 42.2k
8
votes
What protocol is this waveform?
Since the FCC authorisation code is marked on the device, you can look it up on the FCC database.
If you enter the first 3 characters (SH6) as the grantee code, you get a list of devices from that ...
- 1,465
7
votes
What is the source of this shape on my USB eye diagram?
This is absolutely perfect FS signal. Apparently the OP probes the signals at device end of the cable. The FS signals are unterminated at FAR END by USB standard, unlike in high-speed mode. All ...
- 41.9k
7
votes
Voltage spikes in triangular waveform generator circuit using LM324 op amp
This is a great example of why the various physical limitations of different op amps need to be considered.
You're correct, it is not a pole. In fact, it's got nothing to do with the circuit itself, ...
- 29.2k
7
votes
Accepted
Peak to Peak vs. Amplitude
I think that the historical definition of amplitude comes from nature. When Earth was young, most things that were wavey tended to oscillate sinusoidally about a middle point. Think sea waves or a ...
- 7,601
7
votes
Accepted
Square wave to DC voltage with passive components
The following voltage doubler may give you what you want
simulate this circuit – Schematic created using CircuitLab
It presents the peak to peak input voltage to the output, less two diode ...
- 171k
7
votes
SPI waveform on Raspberry Pi is not clean, and I'm wondering why
The spikes at the rise and fall of the blue signal are probably due to probe inductance (aka long GND wire connection). Try using as short as possible GND connection.
Also as much as possible, for ...
- 311
7
votes
Accepted
Waveform at the negative terminal of an OPAMP
In the circuit, you have posted the Opamp dos not work in a linear region.
More about the linear operation you can find here:
Op-amp: Virtual ground principle and other doubts
But instead of this, ...
- 15.4k
7
votes
Accepted
Waveform result of an equation
Do the analysis graphically.
Any red section in D, E or F will cause ...
- 2,895
6
votes
Wall power socket outlet: square or sine wave?
Utility power generators produce three-phase sine power. One reason for this is that the power is constant within a cycle. That means there is no torque ripple on the generator shaft. If there was, ...
- 314k
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