@Hypnotia yes, I have some sticks available. I already sent you a pm.
I did some tests with different kind of CC2531. I testet 3 versions.
- my own sticks
- a new mod which was discussed above (with copper foil)
- chinese stick with antenna
Pictures of the sticks:
And this is the linkquality of a Router, which is about 10m away (2 walls in between) from the coordinator (which is located in a cupboard). The sticks were always placed on the same position. Also same antenna direction.
As you can see I get the best values with my own modded stick. The copperfoil Stick was only inserted an hour, but you can see that the values are lower than before.
The premade Stick from china also has lower values and after some hours the value started to fluctuate (but this is pretty normal, I also saw this with my stick).
At the end I repluged my modded stick and the value went up again.
So for now I will keep making the sticks as before. The mod seems to be good as it is. But I’m always open for any suggestions.
Interesting
There are many parameters that can influence
The output impedance of the transmitter may be designed with the integrated antenna in mind and be different from 50 ohms which is what an external antenna is normally made for. The old antenna in series with a ground pin may do a favourable impedance transformation.
The external antennas could be pretty poor so that the old integrated antenna actually still helps.
The polarity of the antenna is important. To get optimal transmission between two antennas they have to have the same polarity. When the USB stick is standing up with the external antenna is vertical the old integrated antenna is actually horizontal. Now in practical you have no idea if a light bulb is vertical or horizontal but you can actually see differences between how you hold the antenna if you look at real instruments. It can easily be 10 - 20 dB difference in RF signal strength
And if the 3 mods create different polarisation then two that are the same will work better.
Last we cannot know where the ground on the stick may be more noisy from the digital circuits.
Looking at the copper foil mods. I talked to my RF engineers (I manage a radio development team) and they said that the best is the foil only at the bottom. This is also what I did on mine. I suggested the top foil as a way to improve but it may turn out to be not such a good mod. If you feel like it you may try only the bottom foil. And to get correct correlation the receive and should have same mod or be well controlled to be vertically polarised. RF is fun to work with but also difficult and difficult without signal generators, network analysers and spectrum analyser. Maybe I will buy a few extra of the standard sticks and have a play with it. I have access to the expensive equipment at work.
No matter what - your sticks work great - and that is what counts. it is only for learning and optimising. I would not hesitate to recommend your sticks - just based on the reputation and the picture. Beautiful work you do.
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I’d be curious to learn if the following modification has any measurably impact on the performance of the ‘chinese stick with antenna’:
- Extend the ground plane underneath the board so it fills in the gap between the two antenna pins (like what was done for the ‘new mod’ version).
I realize one goal of buying the ‘chinese stick with antenna’ would be to spare one the trouble of making modifications. Nevertheless, it might be interesting to learn if this one small mod produces any detectable benefit.
If successful, and it performs well, using these sticks may spare h4nc some time building his finished product.
When I look at the picture it seems there is a small via on the signal path on the Chinese mod. It looks strange why it is there. But it would make it bad to cover the area with a foil. You would get a ground too close to this via which seems to be the signal path. That would probably make things worse
Seems like you are right. I did some additonal tests. My stick still gives me the best results.
- Copper foil mod, without top foil, cut trace on left top pin
- Chinese antenna mod stick with soldered plane
Linkquality:
The next thing I’d like to share with you is little project that was inspired by this:
DIY Smart Doorbell for just $2, no soldering required » Frenck.dev
The thing is my doorbell is very old and it is directly driven by 230V. I didn’t want to open any walls to pull new cables, so this is the solution I came up with.
I use a zigbee door sensor for this. I opened the case and soldered two wires to the reed sensor solder pads. These cables are connected to a phototransistor (mind the polarity, short pin goes to ground).
As I said the doorbell is driven by 230v. I connected a little 230V bulb to the bell. This way it lights up when it some one pressed the switch.
This can now be measured by the phototransistor (basically this is a selfmade optocoppler). Bulb and sensor are covered with black tape (don’t have a pic of that).
Some pictures:
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Ouch! Yes, I see that now.
And we see that in the graph above.
Did not here about that one yet. Is it supported in zigbee2mqtt? Could you provide a link.
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Hi @h4nc,
so after some research and some tests I can tell you adding an external antenna to WIFI also extend BLE range.
By how much I do not know but I had some MiFlora which, with standard ESP built in antenna were not reachable while with external one they were.
This:
LINK
is an example of ESP 32 board based on WROOM-32U which is built for Ipex antenna.
A simple 2.4Ghz antenna with SMA connector works perfectly (and also boost WiFi signal).
It would be really nice if you could add this option too your RF/BLE gateway: I would buy it straight away!
Thanks for sharing your experience. So you uses the board in the link and added an antenna to the connector right?
If I add this option, I will post it in this thread.
exactly
I added something like this: Link
you can find a ton of different shape also internal ones: Link
should be an easy add-on to your project!
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I finished the IR Versions of the OpenMqttgateway.
I made two versions:
OMG ESP32 IR/RF/BLE/LED
OMG ESP8266 IR/RF/LED
This is how they look:
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Oh My God, nicely done! Looks more like a consumer device than DIY.
How far will the IR reach?
Would it be possible to run Esphome on them (pros/cons)?
Thank you very much, that’s very nice.
I did some tests with an IR bulb to figure out the range.
I worked reliable within a diameter of 6m around the device (so 3m from the OMG with transparent case on top to the bulb in all directions). It worked up to 10 m around the device but not a 100% reliable.
The transparent print takes a little bit of the range (maybe around 0,5m), but it looks way nicer with the cover.
Users could also try to point all leds in their needed position to make the range better.
About ESPhome. I don’t have experience with that, but I don’t see a reason why it shouldn’t work with it. The pins that are uses are directly marked on the pcb.
Hi @h4nc and thank you for this amazing work!
I’d like to order a stick (or two), could you PM me the price and details (as I cannot yet since I just registered).
Thanks
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Hi @h4nc.
Do you still sell the zigbee sticks? I have sent you an email with questions.
Best regards
Petter
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