303.9 Mhz RF Transmitter

Troubleshooting
21

It looks like the Sparkfun 315MHz transmitter circuit is much different than the Murata reference design. The oscillator is on the collector side of the transistor, and integrated with some inductors and caps, so it’s likely part of a tuned circuit. I’m starting to think you might need to tune this guy a bit, but it’s really so close in frequency already it should be oscillating I think… maybe just not as ideally as it could.

It looks like the GND pin is in the same spot as the 315MHz SAW resonator…

1 Like
22

Hey @Carsten4207 hows your progress with this?

Just sat down to finally build the board you sent me… but i dont know where i put the opto’s i ordered ages ago! way to many bags of bits for unfinished projects :slight_smile: will have to keep digging :slight_smile:

23

@BDub sorry been busy with work and haven’t had much time to play with this.

But I will try to build my own transmitter based on the schematics from your previous post. Once I get all the parts ordered!

1 Like
24

@Carsten4207 thank you for sharing your progress on github with this project. I am currently working on a project with an arduino, smartthings shield, and the same remote and it’s all being controlled by the smartthings hub. My remote board is a little different but it runs on the 303.9 MHz. I was wondering if you have had an issue with range. I have 5 fans throughout the house and the set up can only reach 2 of them. I’m ok with coding but electronics isn’t my stong suit. I can’t quite figure out where I would solder on the antenna, any chance you could help. I attached a photo of where the antenna is.

25

Actually I never really researched the core and photon boards. Just ordered a couple of them and going to use this to wire everything up and found script to control it from the smartthings. Still need to wire up an antenna to the remote though.

26

I have mine located upstairs in the center of the house and its able to cover the entire house (2100 sq foot).

What to modify to extend the range is beyond me unfortunately.

27

I connected a 1/2 wave antenna to the remote just now and i think it’s going to work out. Not sure why the 1/4 wave antenna didn’t work.

28

@BDub The words Spectrum Analyzer and cheap should never be used in the same sentence.

29

True, but I’d rather have a cheap spec anz than no spec anz at all :wink:

30

I may have found the best version of the RTL SDR. It is sold on amazon.com. Here is some text from the site

Includes 1x RTL-SDR Blog brand R820T2 RTL2832U 1PPM TCXO SMA Dongle, 1x 6cm to 20cm telescopic antenna, 1x 20cm to 1.5m telescopic antenna and 1x 4.5cm diameter magnetic mount base with full braid RG174"
here is a link http://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Telescopic/dp/B011HVUEME/ref=cm_cr_pr_product_top?ie=UTF8
What do you think?

31

did you ever manage to find an off-the-shelf 303mhz TX for what you needed? I’m trying to solve the same thing for an older Garage Door (Tiltamatic TRG-300) that seems to operate at 303 mhz.

32

Unfortunately no. I couldnt find a Transmitter that worked on that frequency.

If you happen to find one, let me know.

33

I know I am late to the discussion, but have you thought about cannibalizing one of your remotes and changing the physical switches on the remote with electronic components like transistors or triacs? I don’t exactly know the engineering behind this, but you wouldn’t have to develop a transmitter and you could just incorporate the existing Hunter remote in your project container.