Piezo-electric device cut at a specific resonance frequency, mostly used in oscillators.
5
votes
1answer
214 views
MCP79411 not “ticking”
I'm using the Microchip MCP79411 Real Time Clock. I can communicate with the device, read the MAC address from it, write to the EEPROM function and read back those values, but the Time and Date ...
7
votes
1answer
239 views
Oops: shielded inductor very close to a crystal. Problem?
I've got a design that worked great on the two boards I hand assembled, but more than half of the boards from the local assembly shop are bad.
I've traced the most common failure mode to an unstable ...
4
votes
2answers
476 views
Load capacitance for RTC Crystal
I'm working with an LPC2387 (datasheet), and pp. 55-56 of the datasheet specifies several options for the RTC crystal with different load capacitance: 11pf, 13pf, and 15pf. For each of these crystals, ...
7
votes
2answers
453 views
How far is “too far” when routing traces for crystals, and how asymmetrical is “too much”?
I'm routing a breakout board for NXP's LPC23xx microcontroller. This MCU requires two crystals if one is using the RTC. These two crystals connect to the MCU with only 3 pins in between:
From this ...
2
votes
4answers
385 views
Simplest 42.8 MHz generator
What is the simplest way of generating 42.8 [MHz] square (or sine) wave? I want to clock fast ADC for SDR purposes. I thought about wideband opamp and 10.7 [Mhz] cystal 4th harmonic. Is there any ...
0
votes
1answer
490 views
Choicing crystal or external oscillator for time critical project on PIC18F
Need to learn how making frequency counter (or any time critical project) using PIC18F that display output over USB.
Having choice of 3 clock sources:
±50ppm 4.0000 MHZ crystal ATP040SM
4.0000 MHZ ...
1
vote
3answers
280 views
Stray Capacitance for Crystals
I am trying to set up a circuit with a 14.31818MHz crystal (PAL decoding). The data sheet for the chip, using the crystal, states the relationship between the two capacitors, connecting the crystal to ...
0
votes
1answer
175 views
Best oscilator scheme for watch crystal
I wonder, what's the best oscillator scheme to use with watch crystals(32kHz) to get optimal stability & precision? (provided that temperature is stable, digital correction is out of this topic).
...
3
votes
2answers
283 views
Are there any commercially available crystals in the sub 32 kHz range?
I'm looking for a low power clocking solution and it looks like crystals bottom out at 32 kHz. Are there any low power (nA) solutions (crystals/ceramic resonators/custom transistor oscillator ...
9
votes
5answers
568 views
What's the schematic to share one crystal with two micros?
How do I share a single crystal (not a complete oscillator module) between two micros? Is it OK to just connect everything as normal for the first micro and also directly connect its XO to the XI of ...
4
votes
1answer
4k views
How to design the capacitors used with Crystal Oscillators?
I have seen circuits involving crystal oscillators connecting two capacitors between each of the crystal legs and ground. I would like to know how to design the value of these capacitors for different ...
3
votes
3answers
1k views
Crystal oscilator not oscilating on a PIC
I am experimenting with a PIC16F84A at the moment.
I can get this working fine using an RC network for the clock.
When I switch to using a crystal (the usual xtal across pins 15&16 with 2 caps ...
4
votes
6answers
391 views
What is the optimum distance between a micro-controller and a crystal on a PCB?
I wanted know what should be the optimum distance between a microntroller(AT89C51ED2) and a crystal of frequency 11.0592MHz?
2
votes
4answers
494 views
What's causing my 7.3728 MHz xtal to be unstable?
I'm using a 7.3728 MHz HC-49 crystal with 22pF disc ceramic load capacitors. I'm doing this on a breadboard, but I've had prior experience with using a breadboard for this and it has worked well, so ...
1
vote
1answer
136 views
Crystal for HVProg
I am going to make an HVProg.
Can I use an 8 MHz crystal rather than a 7.3728 MHz crystal?
3
votes
5answers
359 views
Multiple crystals
I am building clock with ultimate precision.
There are few known ways to improve precision: temperature controlled environment and multiple crystals. I am implementing both.
I was going to use 5 ...
6
votes
2answers
597 views
How should I select my crystal frequency?
I have seen questions like this that talk about selecting a crystal for UART and I have seen questions like this that mention 32.768 kHz for RTC. But how do I decide the right crystal for my ...
3
votes
2answers
458 views
How do I choose the correct capacitors to use with my Crystal?
I am looking at using this crystal for a new circuit design. It will provide the main oscillator for my PIC application.
Here is the part on digikey: ...
5
votes
1answer
802 views
Real-time clock and Crystal precision
I want to use a crystal as the base clock for a watch.
Most reference designs I could find use a 32.768 kHz crystal at 20 ppm (parts per million) precision.
According to my calculations, this leads to ...
10
votes
2answers
223 views
Difference between crystals?
Is there any point in using a big crystal over a smaller one? Apart from the tolerance spec, how come crystal manufacturers have all these different models of crystals from really tiny ones to big ...
8
votes
3answers
2k views
How does a quartz crystal work?
Could you explain how a quartz crystal works, maybe with a simple schematics with the essential things ? I know it acts like a kind of stabilizer for an oscillator, but nothing more than that.
7
votes
4answers
946 views
Crystals and Load Capacitance
This feels like a dumb question, but I'm going to ask it anyway. If a crystal has a rated load capacitance of 6pF, is the right thing to do to put a 6pF capacitor to GND on either leg of the crystal? ...
5
votes
3answers
378 views
Does the frequency of a crystal influence its height?
Here is a picture of two crystals:
Does the difference of frequency explain why the 6Mhz crystal on the right has a lower profile than the 5Mhz one ?
4
votes
2answers
223 views
Crystal radio as user interface problem
If I built a coil like the one in this crystal set.
How could I use a micro to detect which point the alligator clip is on?
Basically I wan't to use the crystal set as a user interface for an audio ...
