# Crystal Based Oscillator

Hi All,

I am revisiting a electronics project i previously worked on in which a circuit was devised using a 555 timer to create a astable 56 Khz square wave, the reason for revisiting was because thermal drift and overall circuit capacitance with electrical noise resulted in poor reliability and operational efficiency in the resulted waveform.

I am looking to create the same circuit with higher efficiency and reliability from a crystal based oscillator however this part of my knowledge is few and far between, i have been reading about colpitts, pierce, CMOS and microprocessor crystal circuits however i can not find information i can understand on how to accomplish this.

My working voltage is 5 volts any help, advice or information would be greatly helpful, the circuit type would be a great starting point in the meantime i will continue researching.

Thanks in advance, Chris.

You are not going to get a crystal that goes off at 56KHz. If you could get one made then it would be rather large. What you have to do is to get a much higher frequency, say 1MHz and use a counter chain to divide it down to your required frequency.

What is this particular method called i've heard people discuss divisions of crystal frequencies but no body names the type of circuit could you provide an example circuit or what could i type into google to get an example of this.

Grumpy_Mike:
You are not going to get a crystal that goes off at 56KHz. If you could get one made then it would be rather large. What you have to do is to get a much higher frequency, say 1MHz and use a counter chain to divide it down to your required frequency.

Is there some reason that a 56 kHz crystal would need to be large, but a 32.768 kHz crystal can be made small enough to use in a watch?

I have started watching some tutorial videos online as well as reading on frequency dividers because at current i have no idea how to wire up the frequency divider you linked or what each pin is used for from the data sheet so i will do more research tomorrow but for now its to late thanks.

What is this particular method called i've heard people discuss divisions of crystal frequencies but no body names the type of circuit could you provide an example circuit or what could i type into google to get an example of this.

A [u]Type-T Flip-Flop[/u] is a divide by 2 circuit. Frequency dividers are usually made from flip-flops.

As far as building an oscillator circuit - In most cases, it's easier to buy a [u]crystal oscillator[/u] than to buy a crystal and build your own oscillator circuit.

These circuits are called counters or frequency dividers. CrossRoads gave you a link to them. You need a divide by 6 followed by a divide by 12, because 6 X 12 is ?

Jiggy-Ninja:
Is there some reason that a 56 kHz crystal would need to be large, but a 32.768 kHz crystal can be made small enough to use in a watch?

Google it, the low frequency clock crystals are actually tuning forks.

Why this frequency, and how stable does it have to be.
56kHz sounds like a remote control transmitter frequency.
Done that both with a Cmos 555 and an Arduino.
Both we stable/accurate enough for the task.
Leo..

Shandy:
Hi All,

I am revisiting a electronics project i previously worked on in which a circuit was devised using a 555 timer to create a astable 56 Khz square wave, the reason for revisiting was because thermal drift and overall circuit capacitance with electrical noise resulted in poor reliability and operational efficiency in the resulted waveform.

What are you trying to do ?

555 56 KHz why ?
Do you need a stable clock ?

Go to Mouser Electronics (Mouser.com) and search for the CD4060 chip. Download the pdf spec sheet and it shows a simple way to use the CD4060 with a crystal or resonator (Mouser also has low frequency crystals - tuning fork design which can be used with the CD 4060). You can use the crystal frequency directly, or the CD4060 allows various powers of 2 divisions of that frequency all the way up to 16384. Usually, by picking a common crystal frequency and the correct division, you can get what you want. Multiple CD4060s can be cascaded to get very low frequencies off the oscillator. The CD4060 will run off a wide range of voltages and its outputs are TTL compatible. Available in pin and SMD versions.
Here's a link to the crystals: