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Questions tagged [crystal]

Piezo-electric device cut at a specific resonance frequency, mostly used in oscillators.

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3answers
70 views

What is the purpose of capacitors parallel to crystal? [duplicate]

In many schematics, we have two capacitors connected in parallel to a crystal? Why do we have capacitors parallel to crystal? Whats the purpose? How are the capacitor values determined ?
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1answer
48 views

32khz crystal for AVR. Caps needed?

I remember reading long ago that I don't need filter caps for a watch (32768 Hz) crystal. Is this true? Or will I need to put some capacitors to ground on either end of the crystal? I will be using ...
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0answers
25 views

Programming AT89LP52 microcontroller like an AT89S52

I'm trying to run my code on the new AT89LP52 chip which Microchip (A.k.a. Atmel) believes can be a direct replacement for the AT89S52. I am able to program the AT89S52 with my programmer and ...
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1answer
99 views

Crystal oscillator replaced with exact frequency for clock?

I'm repairing my Nintendo Donkey Kong arcade PCB and I have no pulse when tested with my logic probe. I found out that the crystal oscillator (2 pin HC-18U) was not connected to the board, since the ...
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4answers
98 views

Confusing quartz crystal impedance graphs

I thought that at the series resonant frequency of a piezoelectric oscillator the impedance of the crystal would be the lowest, and at the parallel resonant frequency the impedance would be the ...
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3answers
73 views

What actually is the load capacitance of a quartz crystal?

I'm having hard time understanding the principles of piezoelectric crystal oscillators. I've found this picture: I understand that "load capacitance" is something you have to connect to a crystal. I ...
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3answers
151 views

Rectifying failed MCU crystal oscillator design

I am working on an SMD hobby project (2 layer board) where I use a STM32F405 MCU running at 3.3V, clocked from a 25MHz external crystal. Being impatient, I hastily designed a board and ordered it. ...
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3answers
75 views

Does Crystal/Oscillators package matter?

I design a lot of PCBs that uses microcontrollers with external clocks. For some reason a lot of the example designs always tend to use the big generic HC-49 package. Even factory made modules that I ...
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2answers
87 views

RTC time advancing

I'm working in some projects with an RTC. I'm using the PCF85063A. The problem is: the RTC counter is advancing from real time about 2 minutes per week. I searched for hardware and firmware errors, ...
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2answers
458 views

What is the purpose of this extra PCB pad?

I am looking to use this crystal in an upcoming design and I am a little bit confused by the datasheet. The datasheet is available here: CMR200T Datasheet This is the image in question: Question: ...
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1answer
47 views

Crystal Oscillator Power

In the following circuit: taken from: https://circuitdigest.com/tutorial/quartz-crystal-oscillator How is the crystal powered to begin oscillation? I understand the amplifier is required to prevent ...
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2answers
219 views

Why does this crystal oscillator have a window?

I came across this device just now, and I can't think of any reason for it to have the window that it has. This isn't just a cutaway display image, either; the datasheet specifically mentions that ...
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2answers
72 views

Is an external crystal overkill is this case?

I am designing some boards that are powered and communicate through Cat 5 cables using a bit banged form of protocol inspired by quad spi. Using the bus network topology in a half duplex manner, I ...
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3answers
66 views

Why does antenna tuner in crystal radio use capacitor and an inductor?

I know that antennas can be capacitive or inductive depending on the relation of antenna length to the \$\lambda\$. I know that crystal radios use both antenna and capacitor for tuning and I don't ...
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0answers
27 views

LPC1768 Uart baud rate Problem

I had a problem when I wanted to log my Code Process with UART. It has shown some unknown characters in terminal . It was somehow identical. I used to change a lot of things but no one solves the ...
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2answers
59 views

Speaker for crystal radio rather than sensitive piezoelectric speaker Crystal radio

I am a science student of grade 8 and researching and learning about radio waves. I am currently trying to make a crystal radio. The problem I am facing is the speaker I have to use for the project....
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2answers
252 views

Sharing 32.768kHz crystal for 2 IC [duplicate]

Is it possible to share 32.768kHz crystal for nRF52 and BNO055? The purpose is reducing cost&space. Preferred crystal this one: FC-135R https://support.epson.biz/td/api/doc_check.php?dl=...
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1answer
38 views

Byte-Banging 2 8051's using port addresses

Currently I have two microcontrollers setup in which entire ports are connected to each other (P1.1 connected to P1.1, P1.2 connected to P1.2, etc). I also have two pairs of extra GPIO pins connected ...
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1answer
53 views

Crystal 4 Pins SMD footprint

I'm designing PCB that includes 24MHz SMD 4 pins crystal. According to my understanding, the crystal package marking is for Pin number 4. I wonder, how should I indicate in the PCB this pin? Should ...
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0answers
42 views

Minimalist high speed 8051 microcontroller testing circuit on breadboard

I'm trying to come up with a circuit using the least number of parts possible to build on a breadboard that tests the basic functionality of a microcontroller, specifically the AT89LP4052 ...
2
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1answer
103 views

Separate GND-plane for microcontroller crystal resonator

1.  Background info I'm designing a board for an STM32F767ZI microcontroller. This microcontroller has a primary oscillator for the SYSCLK (overall system ...
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1answer
62 views

How do I keep my LEDs from burning out in a magnetic induction coil?

I built a simple magnetic inductance coil using: For transmitter: 28 awg magnet wire in a "pancake coil" (flat spiral) npn transistor (TIP31C) 2 resistors in parallel battery (tried a 3 volt ...
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0answers
48 views

AT89S52 microcontroller only starts when extra 22uF capacitor touches board

I made simple code for the microcontroller that prints a simple message on the LCD once the microcontroller starts. I arranged my board so that the pull-up resistors and reset resistor (100K) and ...
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1answer
198 views

XTAL resonance increase the voltage

I have a 4Mhz crystal and i connect it in series between the function generator and the oscilloscope probe as shown below: simulate this circuit – Schematic created using CircuitLab However i ...
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1answer
373 views

Frequency response of MCU decoupling capacitor

I'm designing a board that contains an MCU and an 8 MHz crystal. I was planning on keeping the MCU power/ground localized and isolated from the main power supply power/ground except at a single point. ...
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2answers
152 views

32.768 kHz Crystal Troubleshooting

I'm at my wit's end trying to get a 32.768 kHz tuning fork crystal to work and I don't know what I'm doing wrong. First, some background: I'm using a 16MHz crystal in conjunction with an Atmega 328P-...
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1answer
171 views

Why do some Arduino-compatible boards provide a crystal for the CH340? [closed]

I have an uno-shaped Arduino compatible which uses the CH340(G) serial to ttl converter chip and it is connected to an external crystal. I also have nano shaped compatible which uses the CH340(C) ...
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1answer
39 views

IN/OUT pin of the crystal circuits [duplicate]

Got few questions about the input/output pins of a crystal circuit. As shown above, it's a common clock circuits. My question is: 1. If we want to measure the waveform of the clock, which pin should ...
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3answers
193 views

Can I get away with that poorly designed board?

I am designing a board but space is not a luxury that I have at the moment, can I get away with that design or I must use a SMD resonator?
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2answers
88 views

Is it better on two closely connected microcontrollers to send nibbles with an ack or a byte with a delay for an ack?

I'm trying to figure out the best approach to transfer high-speed data one way between two microcontrollers (with their own crystals of the same speed) of the same variety (between AT89C4051 and ...
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1answer
67 views

How to connect the PHY crystal for RMII?

I'm attempting to implement Ethernet communication for the first time and have run into an issue with my PHY. I'm using the KSZ8091RNBCA. According to the datasheet, when running in RMII mode, the XO ...
1
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1answer
43 views

Thin plate piezoelectric transducer glued to flat surface in shear mode

I want to glue a piezo plate looking like in the image below such that the wide surface of the plate gets glued onto a flat surface. The image is part of the datasheet from here. If I apply an AC ...
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1answer
63 views

Crystal reference and capacitors for w5500

I'm selecting the caps for the crystal oscillator of the wiznet W5500. The standard Load Capacitance for 25Mhz crystals is 18pF. I found out that the hardware guideline claims for a Load Capacitance ...
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1answer
54 views

Choosing reactance of LC tank for crystal oscillator

In the ARRL (2011) Section 9.5.4 (talking about a series mode quartz crystal oscillator) it says: To build a practical oscillator from this circuit, choose an inductor with a reactance of about ...
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3answers
118 views

Is this an acceptable 100Mhz OCXO output?

I was looking for a 100Mhz sinwave OCXO output. I picked up a used one and I have the following output: Each vertical square is 1 volt. I was expecting it to look exactly like a mathematically ...
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1answer
81 views

Quartz Clock Accuracy

Do the vibrations of aircraft engines (or any engine, for that matter) dilute the accuracy of a quartz clock? I haven't done any kind of research or hypothesis testing, though I believe that the ...
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1answer
130 views

feedback resistor value for a crystal oscillator

Does the feedback resistor for a crystal oscillator need to have a very accurate value? If a 16Mhz crystal requires 1Mohm, should one expect a problem when 200kohm or 2Mohm is used instead?
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1answer
56 views

TUSB2046B crystal not oscillating

Further to my previous question, I also noticed that the crystal there was a 12MHz where this should have been 6MHz (due to an inventory error - the wrong part was fitted). I've removed the 12MHz ...
2
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1answer
66 views

Tuning Fork Crystal grounding

This post is very helpful, but I'm still a little unsure about my crystal layout. This is a 4-layer board with top_signal->ground->+5V->bottom_signal stackup. The crystal is a 32.767KHz tuning fork ...
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2answers
155 views

Measuring crystal drive strength without a current probe

TL;DR Is there a means of measuring the crystal drive level reliably using voltage measurements (even with a differential voltage probe)? Background: I am attempting to measure the crystal drive ...
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2answers
136 views

Crystals, capacitors and W5100

Background: I have built a number of devices based on the W5100 chip, all them were (are) working more or less decently. However last batch currently in testing show faulty behavior - almost all of ...
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3answers
139 views

Crystal's ESR or Frequency Stability/Tolerance, which is more of a priority?

I'll be using a 12MHz crystal, CL=20pF on an NXP chip. Currently choosing between lower ESR (60ohms vs 100ohms) or lower stability (50ppm vs 10ppm). Which spec is more important? Should I choose a ...
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3answers
495 views

For a crystal oscillator circuit, what effect would a series resistor have on the inverter input?

In some application notes, there is a recommendation to use an external resistor in series with the OSC_OUT pin to reduce the power dissipated by the crystal, if necessary to do so. A good example is ...
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0answers
93 views

Use an ATtiny85 instead of an ATtiny13 - Where do I place the XTAL?

Having looked at a circuit diagram in Beginners Introduction to the Assembly Language of ATMEL­ AVR ­Microprocessors by Gerhard Schmidt, I came across a circuit presented by the author (in which an ...
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3answers
2k views

Strange crystal schematic notation appears un-connected

I'm transcribing a Cypress CY8CKIT-059 schematic for use in my device when I came across this curious notation for the crystal: What does this mean? Like normal, I assume it is connected across the ...
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2answers
147 views

Using a 16MHz crystal with an atmega328, it works only if I remove the two capacitors connected to the crystal

I am using a 16MHz crystal with an atmega328. I added two capacitors to the crystal as usual. Everytime the capacitors are attached, avrdudee does not recognize the atmega. Once I remove the ...
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1answer
77 views

Incorrect XTAL waveform from PCB

I have been made my first digital clock circuit, but it still not working. After I test many ways, I find the problem on the crystal. The waveform graph of XTAL from my pcb And this is the correct ...
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1answer
134 views

What do these SMD crystal labels mean?

I’m trying to identify these 32.768 crystals from the label but can’t find them. What do these markings such as 32C446 and 32C416 mean? The actual part I want to identify is marked with 32C446.
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5answers
1k views

Change in resonant frequency of quartz crystal with atmospheric pressure?

We have a bare quartz crystal and we are measuring its resonance frequency to a very high accuracy (1 ppb). As it cycles between atmospheric pressure and vacuum there appears to be a change in ...
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3answers
513 views

How is crystal frequency set?

When you purchase a crystal to use as a clock, the company is asking you exact frequency to set it at. I remember needing a crystal that was 4x the NTSC color carrier and they were asking me how many ...