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Questions tagged [crystal]

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

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Why there is no a variable-frequency crystal oscillator?

Quartz crystal oscillators have better frequency stability than tuned circuits of capacitors and inductors. However, they are used only as components with a fixed resonant frequency. Variable-...
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3answers
1k views

How does an ARM MCU run faster than the external crystal?

So before this I only worked with simple 8 bit Atmel MCUs and I realized on my development board schematics it has only a 12Mhz crystal, yet the MCU operates at up to 100MHz. (I think the default is ...
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40 views

Could an external circuit with 74HC series IC reliably test a 24 MHz crystal?

I made a circuit where the microcontroller works. I made a duplicate of the same circuit with a working micro, but that circuit does not start and there is no smoke and the PCB is clean (no loose ...
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19 views

epson crystal markings

I am looking for MFN of two crystal units. 1- The marking on top is A833L. It’s a 32kHz crystal unit. Two terminal SMD. 2- The marking on top is 3200P E88W8. It’s 32MHz crystal unit. 4 terminals ...
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1answer
101 views

What are these two components ? I can't identify them

I'm having a hard time finding what these two components are.i can't find them anywhere. The first one is 3 leg MOSFET which has PDB marking on it and DD on the silkscreen The second one i can't ...
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2answers
62 views

Load capacitance of crystal

I know this question has been asked many times before, however this question differs in the use of an uneven set of capacitors. I'm replacing the crystal on an old computer. The original symptoms ...
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2answers
90 views

PCB Crystal holder

I am designing a PCB consisting a microcontroller in which I have to ensure that I have removable crystal . I am looking for a female connector in which I can easily plug/unplug/swap the crystal (...
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1answer
39 views

ATmega crystal setup and and power routing

I have finished designing my first circuit boards and am uncertain about a couple of things. First of all, I know that I should connect both sets of ground pins and +voltage pins on the chip. My ...
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2answers
25 views

Which pins should i use to connect watch crystal for powering Low Frequency Crystal Oscillator in ATmega328p?

If i want use a watch crystal(32KHz) with Low Frequency Crystal Oscillator of ATmega328p,Which pin should i connect the crystal to? Should i connect the crystal to XTAL1,XTAL2 pins of ATmega328p or ...
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1answer
87 views

Understanding this crystal connection

I have been working on design for which I have a reference schematic. I came across the following crystal setup: I've always seen crystals being connected to two pins on an MCU, like XIN and XOUT ...
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1answer
42 views

Voltage divisor on a oscillator output using Capacitors vs Resistors

My question is pretty simple. Why does this chip datasheet suggest to use a voltage divisor using capacitors? Does it make a difference to use capacitors instead of resistors? Edit: Link to datasheet ...
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2answers
81 views

Crystal oscillator producing straight line only

I have replicated a crystal oscillator circuit from internet, but the output waveform is a pure DC rather than the expected sine wave. Below are my circuit diagram and the simulation output from ...
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71 views

Crystal Oscillator (STM32F4)

I am currently working with a STM32F427 MCU and have a few questions in my mind. Is my schematic for the HSE correct? Can you tell me, why some schematics on the Internet use a Resistor in series ...
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1answer
74 views

pcb-4-pin passive crystal is soldered to a 2-pin crystal PCB package

I would like to know whether it is suitable (not harmful) to put a 4 pin passive crystal in a 2 pin footprint. Thanks in advance. I have a 2 pin footprint in my PCB board,however,I only have a 4 pin ...
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3answers
87 views

Generate a false encoder signal CW/CCW 1/4 shifted

I need to generate a 10-100khz square signal freq. to simulate an encoder. I'd like to be able to simulate CW and CCW, shifted by 1/4 th signal. I've thinked about a crystal with a pot and some logic ...
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2answers
66 views

Designing a deterministic-startup precise oscillator

The problem I need to reliably generate a sequence of events based on a digital input trigger signal. With minimal jitter and a predictable deterministic delay. 2 to 5 events The events will be from ...
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37 views

How to change Oscillator Speed for the AT89c51 MCU?

My experience with embedded electronics is using ATMEGA328 with the arduino. I am aware that to change the crystal frequency from 16 MHz to 12 MHz on the ATMEGA328, requires a change to the final code,...
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21 views

Cutting liquid crystal valve

i need circular liquid crystal valve and I couldn't find anything on the internet. I've only found maybe 2 or 3 variants of it and that is square or rectangle so I was wondering if I can cut the lc ...
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2answers
57 views

How does load resistance affect the function of this crystal oscillator?

Related Load Resistor across Crystal - though that's for a passive crystal and not an integrated XO. Summary I'm considering using an Epson TG-5035C XO and am figuring out the circuit necessary to ...
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1answer
73 views

Does this clipped-sine oscillator need a buffer?

I'm considering using an Abracon VCTCXO, the ASVTX-11-121-19.200MHz-T to run an AT89LP428. I'm trying to make sure that they're interoperable, but the Abracon device doesn't say anything about the ...
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3answers
117 views

Why is my crystal oscillator not working with KSZ8999 switch?

I am using KSZ8999 ethernet switch from Micrel and I have problem with 25 MHz external oscillator. There is constant 2,1 VDC on output pin which is VDD for the switch, so crystal is not oscillating. ...
2
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2answers
407 views

Crystal compensation for temp and voltage

Introduction I'm toying with the design for a fail-safe wall clock controlled by multiple 32.768kHz crystal oscillators. I'm currently reading about compensation. Compensator from literature From ...
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1answer
48 views

{enc28j60} Is the 50ppm crystal good enough

I have some 25MHz 50ppm crystals but I am not sure if they are good enough to be used with ENC28J60.
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1answer
32 views

STM32F405 Internal vs External Oscillator

If the frequency stability over a temperature range is not a concern in a project instead it's reliability in continuous long time operation is a more important factor then which of the two ...
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3answers
187 views

32.768kHz crystal making audible noise

I am doing a project to record and log the voltages of an 8 cell lithium battery. The project is based on an STM32 microcontroller, and logging is done on an SD card. I have made the first version of ...
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1answer
47 views

Zero-R Resistor on XTAL pins

Looking at the schematics of the STM32F4-Discovery board page 28, whose screenshot is attached below.. there is a Zero Ohms resistor 'R25' which is shown in the circuit with the Crystal. And there is ...
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0answers
54 views

How to place parts crystal oscillator in DipTrace

I'm now into DipTrace and getting used to it. I placed parts by placing parts' standard like QFN-32, ESP8266EX etc... but I'cant find the way how to place a crystal oscillator. This is the one that ...
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2answers
54 views

STM32F407 fallback to Internal Osc

I wonder if it is possible at run time to detect that an external Oscillator has gone bad and the application now falls back to internal Oscillator.. specially for the case of STM32F407 MCU?
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1answer
74 views

Selecting true crystal settings for 328P [7.3728 MHz]

I want to make a new board working with 115200 (gsm modem) UART. so I want minimum baud error rate. I look at https://cache.amobbs.com/bbs_upload782111/files_22/ourdev_508497.html table and decide ...
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2answers
107 views

Problem configuring RTC of STM32F4 using LSE

I want to use RTC of STM32F4. When I configure this with LSI, I have no problem. But when I use LSE, I have a timeout error in SystemClock_Config function when it ...
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2answers
156 views

Testing crystal oscillator with multimeter crashes system

I have an old XT computer with a crystal oscillator that I would like to test. My multimeter has a Mhz setting that as far as I know should allow me to test it. (Providing the crystal is powered) ...
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1answer
204 views

Do crystals have polarity? [duplicate]

I have a quartz crystal and I am connecting it to a microcontroller's EXTAL and XTAL pins. Can I connect it anyway? Do the crystals have polarity? In EXTAL and XTAL, which is input and which is ...
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2answers
262 views

How do crystal oscillators start?

I have read the answers to the question,"How do crystal oscillator start to work" in this forum. And the common answer which I got is that, there are many frequency around the crystal. The crystal ...
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3answers
83 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
60 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
39 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
127 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
220 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
272 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
172 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
88 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
93 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
469 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
56 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
237 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
73 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
180 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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2answers
113 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
321 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
42 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 ...