Need circuit for an oscillator.

Posted by: @sj_h1

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I need an oscillator circuit for general use in the range of 1 to 5 Mhz. It can be crystal. It can also be fixed frequency although I would prefer variable. 

 

Does google not find any?

@zander Everything I found on Google is in the Khz range. I need, at least, 1 Mhz.

@sj_h1 Try putting 1mhz to 5mhz in the google search. Here are a few hits I found

https://mysite.du.edu/~etuttle/electron/elect16.htm

https://amz.run/6KQ5

https://www.electronics-tutorials.ws/oscillator/crystal.html

Click on Images after the search

https://www.google.com/search?newwindow=1&sxsrf=AJOqlzXEFOloEH15inOHUcrsoZifN1oSDA:1674399294567&q=var+freq+oscillator+1mhz+to+5mhz&tbm=isch&source=univ&fir=MrcZ1lifT8M9PM%252Cd5NtEIafsw0uEM%252C_%253BlxVTk6-bSTAjLM%252C6qLcH7Ib1jpTnM%252C_%253BJC5oGIGLcVO97M%252Cj6IUywGhTOfXLM%252C_%253BOo6gx4iZtBanxM%252CKHTKqjn7cX6rWM%252C_%253Bcf3B4uBxvELtLM%252Cj6IUywGhTOfXLM%252C_%253BGigbxf5ssdZPVM%252C937PHIRkmrUnsM%252C_%253BRWUBQZw1fDClIM%252Cj6IUywGhTOfXLM%252C_%253BPIXt0MLN-ibovM%252C937PHIRkmrUnsM%252C_%253BD296pAmwheD4mM%252C2rl7QMry8XibcM%252C_%253BAyGQ6iXA7RNaGM%252C0dd7KCFxsJg6FM%252C_&usg=AI4_-kSyCjAIzDJ5-CkRH75kAKvkKDpP1w&sa=X&ved=2ahUKEwj4vai5t9v8AhW6BjQIHTFsAtQQjJkEegQIKxAC&biw=1245&bih=677&dpr=2

Posted by: @sj_h1

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@zander Everything I found on Google is in the Khz range. I need, at least, 1 Mhz.

 

Hi sj_h1,  I found this oscillator circuit tutorial , it has a lot of information on different types of oscillator, how they work, and how to design one...You might look into the Ne555 timer chip as an easy way to design an oscillator in the Astable mode. link: http://staff.utar.edu.my/limsk/Analog%20Electronics/Chapter%2016%20Oscillator%20Circuits%20and%20Applications.pdf

good luck..

regards,

LouisR

Hi @sj_h1,

  You have received some good suggestions so far.

  If you are still looking, may suggest you clarify the type of output you require. e.g. 3.3 logic, 5V logic, sine wave of ??V magnitude? Do you need a particular frequency .. above 1MHz is rather broad for a specification.

NB I am including references to a few adverts I found below as examples ... they are only convenient illustrations of what I am describing, not recommendations of particular suppliers or components.

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If it is logic level, and a fixed frequency, then there are a lot of 4 pins/pads devices. e.g. https://www.digikey.co.uk/en/products/detail/ecs-inc/ECS-2520MV-080-CN-TR/9742386

This is a physically small device, with surface mount pads, which may be good or bad news, depending on your capability to handle SM and the amount of space available. In the past, larger versions with pins, of the same basic shape, were common. They are still available, but you might have to look harder.

e.g. https://www.aliexpress.com/item/1005004154484021.html

When looking, beware that similar looking devices, which are often described as 'crystal oscillators' in the adverts, are actually just the crystals, At the very least, check it has a pin/pad layout with power pins (e.g. 3.3V or 5V) and ground.

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Alternatively, you might want to be able select different frequencies. These are 'modules' which combine  a crystal oscillator with a programmable frequency divider chip.

As a 'raw minimal' example I found:

https://www.aliexpress.com/item/1005004671909422.html

This is a small PCB with essentially just the two main items. To select a frequency, you will probably need to connect it to an Arduino or similar, and control it via the data bus connections.

NB I noted some comments about waveshape in the advert ... if you are looking for a logic level output, you might wish to buffer the output, perhaps with a 74HC chip, to ensure the logic signal looks like a square wave. I haven't used one of these devices, so this is just a suggestion.

The original chip designer's data sheet should explain more. e.g.

https://www.analog.com/media/en/technical-documentation/data-sheets/ad9850.pdf

As I said, this is a 'raw' example ... if you look around, you will also find more 'packaged' versions, may be with switches to select frequency and display of chosen frequency, but obviously they may also be larger and more expensive.

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It all depends on what you want to do. Good luck in your search.

Best wishes,

Dave

@zander That is what I was looking for!

@inst-tech Tried the 555 could never get it to work in the 1Mhz range

@sj_h1 Which one?

@davee The AD9850 is exactly what I was tring to build. Thanks

@sj_h1 You should have said that. NOTE: that is a 125mHz NOT 1 to 5. Very strange.

@zander The AD9850

@sj_h1 In the future if you have a part number like AD9850 you should google it, then if you still need help, mention that part in your post here, and maybe say it's a 125 mHz oscillator, NOT 1 mHz to 5 mHz.

Hi Ron @zander,

  The 125 MHz oscillator in the module is a crystal oscillator which is used as the reference input to the AD9850, that uses it to generate outputs, whose frequencies, depends upon the divider parameters chosen by the user. (More generally, the AD9850 requires a stable crystal oscillator in range 1MHz to 125MHz.)

Oversimplifying the details, the output frequency range is (claimed to be) 0-40MHz.

Best wishes, Dave

Posted by: @sj_h1

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@davee The AD9850 is exactly what I was tring to build. Thanks

@sj_h1, Indeed..with that information, I can now rule out the 555 timer to be used for your application as the  555 only has a frequency range of ~ 100kHz to 5mHz.. see link: https://en.wikipedia.org/wiki/555_timer_IC#Derivatives

I think @DaveE outlined what is needed.. good luck with your project.

regards,

LouisR