Trouble sourcing 40.5 Khz oscillator

[wassy]

Hi all,

I'm trying to create a copy of the remote for my gas fire. I was expecting a classic IR blaster, but it turns out it is an ultrasonic transducer arrangement. I think I've successfully reverse engineered the circuit, but it seems it uses two slightly different frequencies to send the two different signals to open the valve and close the valve. These seem to be based on a couple of radial oscillators 40.000 Khz and 40.500 Khz if I am reading the marking correctly.

Any idea how I can source these? I've found one listing for the 40.000 Khz oscillator on AliExpress but I cannot find the 40.500 Khz oscillator anywhere no matter how much googling I do. I've checked out mouser, RS, AliExpress, eBay and LCSC. Any thoughts?

For anyone interested I've attached a picture of the remote and the schematic I have been able to decipher from it. I guess failing that I'd have to create the required frequency some other way. That is a bit beyond my electronics abilities at this moment, but I'd be happy to take pointers on where to start.

[jmelson]

These seem to be based on a couple of radial oscillators 40.000 Khz and 40.500 Khz if I am reading the marking correctly.

These are not "oscillators", they are bare quartz crystals, of the tuning-fork style, similar to the 32.768 KHz crystals used in watches, etc. 

My guess is that they are totally custom parts. 
Here's a way to do it.  Get a 10 MHz oscillator and build an 8-bit binary divider that can be preset to
a division ratio of either 250 or 247.  This will give 40000 Hz (for 250) or 40485 Hz (for 405).
The 40000 is exactly on frequency, the 40485 is .03% low.

Jon

[wassy]

HI Jon,

Thanks for replying. Yes I realised after I posted that I actually meant crystals, not oscillators. Thanks for the tip. I'll have a look into it