Help determining RF transmitter frequency of garage remote

[macavelly]

Hi, first time DIYer here.

My main overall goal is to use a raspberry pi with an rf transmitter module to control my garage door.

First I want to make sure I buy the right rf transmitter but I can't seem to determine what frequency my original garage remote is transmitting at. Attached are photos of the internal pcb of the remote.



The encoder chip is a PT2262 which I believe works with 315 or 433. But where is the transmitter located?

As far as I can tell, typical transmitters look like this https://i.stack.imgur.com/zEOsn.jpg and have the frequency they transmit at written on top of them.

Thanks for any guidance.
Michael

 

[betwixt]

The PT2262 just provides the pulsed codes to drive the transmitter, it plays no part in the transmission itself. The part that generates the transmission is the tiny black transistor beside the blue variable capacitor and some of the components alongside it. Unusually, it has nothing to stabilize the frequency which might actually make it illegal to use in some countries! Regardless, it should have a frequency marked on the outer casing or at least a certification number you can look up. The board itself would have it's frequency decided by adjusting the blue capacitor and it might be tuneable to cover both frequencies during manufacture.

I would guess from the size of the tuning inductor (the copper loop under the round label) it is 433MHz but I could be wrong.

Measuring the frequency is tricky unless you use specialized equipment but if you have an old analog TV, and can tune it to the lowest possible part of the UHF TV band, it would almost certainly pick it up if it was 433MHz but not if it was 315MHz.

Brian.