20 votes

Why is 30MHz Clock signal distorted on oscilloscope?

There are two issues here: Bandwidth and Measurement technique. Bandwidth: Your measured signal is bandwidth limited. A 30MHz square wave has lots of harmonic content and your scope has a relatively ...
Frosty's user avatar
  • 1,037
10 votes

How to test a crystal resonator in board?

As I see, no answer was accepted. Let me offer another answer. Most modern ICs use so-called Pierce Oscillator to generate stable clocks using crystals. Here is the main circuit configuration: As ...
Ale..chenski's user avatar
  • 40.7k
10 votes
Accepted

High pitch audio frequency measuring

Most common audio equipment is set to match human hearing, 20Hz to 20kHz is their operating range. So you want to measure ultrasound, If you want only to measure high frequencies, you can use a bat ...
Juan's user avatar
  • 1,138
8 votes

High pitch audio frequency measuring

By definition of the audio range for humans, beyond 20kHz is beyond audio. There are audio equipment designers such as Rupert Neve who believe the range could be wider, but this is not necessarily ...
Graham's user avatar
  • 6,150
7 votes
Accepted

Differential Amplifier's Unusual Behavior

The first thing I noted when I saw your circuit is that the VAS (Voltage Amplification Stage, as you call it) is directly connected to the feedback network and this implies that its gain and its ...
Daniele Tampieri's user avatar
6 votes
Accepted

Signal power and spectrum analyzer

The actual measurement of Spectrum Analyzers is "power / filter bandwidth". Your spectrum analyzer has a filter bandwidth that you can typically configure. For example, if your filter bandwidth is 10 ...
Marcus Müller's user avatar
6 votes

How are high-speed circuits tested if test equipment doesnt exist?

For some perspective, consider that optical signals are still too high frequency for the instantaneous electric field to be sampled and measured, but there are still lots of different kinds of ...
The Photon's user avatar
  • 130k
6 votes

Is it possible to measure frequency upto 500Mhz with 50Mhz oscilloscope?

Not really. 500MHz is too far above the nominal bandwidth for any aliasing frequencies to get through to the digitiser within it. You can use your scope as a 'back end' for two different types of ...
Neil_UK's user avatar
  • 167k
6 votes

How to find the frequency of any device?

Yes, such devices exists and are called spectrum analyzers. You will also need to buy an near field probe kit, if you want to work with lower frequencies. They do not propagate well through air, so ...
Vladimir Cravero's user avatar
5 votes

How to measure antenna S21?

In a two-port network, S21 is the complex number that describes the linear power gain of the network. (it's kinda backward - S2 is output, S1 is input). It's a complex number because it is used to ...
neonzeon's user avatar
  • 1,835
5 votes
Accepted

NE555P Frequency Drop to 0 after a couple of minutes?

It is very difficult to see, but as far as I can tell it looks like you have the wrong pinout for the 555 timer. The pins on the right-hand side should be numbered 5-8 from the bottom up, not from the ...
DerStrom8's user avatar
  • 21.3k
5 votes
Accepted

Direct frequency measurement with two hw timers

EDIT: Because of the low precision of the HSI - 0.1%, the clock needs to be switched to HSE. I'm doing all of this in cubeMX so I won't be writing out the bits, you can find them in the reference ...
Tomas Svitil's user avatar
5 votes

Simple high frequency (GHz) RF radiation detector

The ISS86 diode has a capacitance of 0.85 pF and, at 5 GHz this is an impedance magnitude of 37.45 Ω making it pretty unsuitable as a diode detector because, in the forward direction, it will rectify (...
Andy aka's user avatar
  • 458k
5 votes

3dB Cutoff Measurement vs (Calculated + Simulated)

So what am I doing wrong? Or what am I missing? It seems as if somewhere in the chain a hidden capacitance is existing. You haven't factored in the output impedance of your signal generator. The ...
Andy aka's user avatar
  • 458k
4 votes
Accepted

Bode plot: meaning of phase shift

Is it the shift of the output compared to the input signal? It depends what you're making a Bode plot of. If you're plotting a transfer function \$V_{out}/V_{in}\$, then yes, it will be the shift ...
The Photon's user avatar
  • 130k
4 votes

Overtones Produced From Speaker Load on Asymmetric Square Wave

First, you can easily make a nice square wave from any duty cycle pulse train by running it thru a toggle flip-flop. That's basically using it as a 1-bit counter. That divides the frequency by 2, so ...
Olin Lathrop's user avatar
4 votes
Accepted

Counting signal frequency with binary counter

Am only going to address your question about reading the count output from a '393 counter. You have two problems to overcome. This counter is asynchronous, which means that a clock input ripples ...
glen_geek's user avatar
  • 25.9k
4 votes

Designing a senvitive frequency to voltage converter

Solution 1) You could just use a frequency counter with a very large count. For example, if you sample over 1 second, your frequency counter would accumulate 5 million counts. If freq was 100 Hz above ...
Vince Patron's user avatar
  • 3,606
4 votes
Accepted

an/prm-10 grid dip question - how the voltage can be negative at the grid?

I was studying tube designs as a child, long before I had any clue how a grounded cathode amplifier might be designed. Which means I don't remember that much. But one thing I do recall, which had ...
jonk's user avatar
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4 votes
Accepted

How can i convert an AC output from an outlet to a digital signal?

This is best done with a opto-isolator. That not only handles the level conversion, but also isolates the digital signal from the AC line. All you really need is a single opto-isolator. However, if ...
Olin Lathrop's user avatar
4 votes

Unit conversion: dBμV to dBm, including measured frequency

The "dBm" is a unit of power where 0 dBm = 1 milliwatt. The dB\$\mu\$V is a unit of voltage where 0 dB\$\mu\$V is 1 microvolt. If you know the resistance of the circuit (often called the impedance) ...
Andy aka's user avatar
  • 458k
4 votes
Accepted

IC for measuring frequency

At 500 MHz what's usually done is to use a lower frequency counter with a prescaler. You should be able to get up to around 50 MHz with a PIC micro, adding a divide by 10 prescaler would get you to ...
GodJihyo's user avatar
  • 23.4k
4 votes

3dB Cutoff Measurement vs (Calculated + Simulated)

Your audio output connector does not have zero output impedance, and your audio input does not have infinite input impedace. The audio output will have some components such as series capacitor fot AC ...
Justme's user avatar
  • 149k
4 votes

How safe is this TrueRife F-122 frequency generator?

It certainly looks like more thought went into it than some other products we've seen here but I agree with your "garage project" assessment. Power transistor heatsinks mounted on printed ...
vir's user avatar
  • 18.5k
3 votes
Accepted

Max frequency that can be measured with Arduino Atmega2560

The Arduino ATMega2650 is listed as having a clock speed of 16MHz, meaning that it should be able to handle this at least in terms of instruction cycles. If you look at the datasheet (P.39) for the ...
Emmett P's user avatar
  • 356
3 votes

Frequency control of vibrator motor

Before even trying a modulation circuit to control the motor, see if it's possible at all. Connect the motor to a variable supply and see if you can get the frequencies you want. Quite possibly, you ...
Olin Lathrop's user avatar
3 votes
Accepted

Does a BNC splitter introduce defects into the signal?

While I don't expect any nonlinear effects that would change the (dominant) signal frequency, the reflections at each interface on your cable will introduce a set of delayed, attenuated copies to your ...
Marcus Müller's user avatar
3 votes

sampling rate and frequency response of a vibration sensor

You need to sample at a (theoretical!) minimum of double the highest frequency you want to measure (Nyquist) and if there are components above half the sample rate they will be aliased down to lower ...
Spehro Pefhany's user avatar
3 votes
Accepted

Count based frequency meter

In general, a digital frequency counter would have a threshold level that it uses to discriminate between zero and one. This could be a set-able threshold or it could be inherent to the hardware, ...
kjgregory's user avatar
  • 1,040

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