318MHz Oscillator?

I'm not an RF guy, so I'm hoping one of my forum friends can help. I'm helping a young colleague with cloning his garage door opening. This system using 318MHz. We don't need a lot of power, just something that can be gated with a small microcontroller.
Jon McPhalen
Hollywood, CA
It's Jon or JonnyMac -- please do not call me Jonny.

Comments

  • jmgjmg Posts: 13,549
    JonnyMac wrote: »
    I'm not an RF guy, so I'm hoping one of my forum friends can help. I'm helping a young colleague with cloning his garage door opening. This system using 318MHz. We don't need a lot of power, just something that can be gated with a small microcontroller.

    If you want to build an oscillator, you could try something like a SAW resonator
    https://www.mouser.com/Search/Refine?Keyword=RO3118

    Or, a more complete cased solution might be what you are looking for ? (something like ?)
    https://www.electrodragon.com/product/remote-controller-315mhz/
  • ercoerco Posts: 19,456
    315 and 433 MHz TxRx pairs are among the cheapest things on Ebay: https://www.ebay.com/itm/263458011149

    Useful info at https://www.romanblack.com/RF/cheapRFmodules.htm
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • Perhaps a propeller chip outputting a 106MHz square wave (318MHz is the first odd harmonic) would work. I know a 555 timer would interfere with AM reception due to all those odd harmonics so it might be worth trying.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • Peter JakackiPeter Jakacki Posts: 8,348
    edited 2019-04-24 - 14:33:43
    You can pickup 318MHz SAW resonators such as the ro3118 from Mouser for around a dollar, just add a couple of transistors and let the pcb track be the antenna.

    Here's a circuit an image of the other side of a SAW resonator pcb I found on the interweb thingy.

    rotx.png
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  • Jon,
    You might be able to generate a 106MHz squarewave and get enough energy on the third harmonic.

    Bean
  • @Peter: I found that, too, and am probably going that direction as I want to keep the parts count very low -- this is a learning project for my colleague. I wrote the code for an ATtiny85 while he watched and we verified the proper timing with a 'scope.
    Jon McPhalen
    Hollywood, CA
    It's Jon or JonnyMac -- please do not call me Jonny.
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