Antennas

Hi @tedbear,

   A 'zero' Ohm resistor and a piece of wire are (essentially) the same thing, so if it is easier to solder a wire, or maybe just a 'splash' of solder, across the R14 position. Just keep it as small and tidy as possible.

If your ESP relay board does not have a resistor in the R15 position, then I guess that it has a slight modification to the PCB tracking, so that R15 is replaced by an extra millimetre of track ...saving another 0.05 cents ... these parts are so small I can completely understand your difficulties and concerns.

Personally, I would be tempted look for  board with socket and external antenna, and accept some less convenient physical consequences at the relay end where components and connections are large enough to see. Of course, if you can get the internal antenna to work, then you don't have a problem.

Good luck with your project. Dave

I found another similar ESP32 relay board.

https://www.aliexpress.com/item/1005002985323087.html?spm=a2g0o.cart.0.0.3fb73c00dd4W2U&mp=1

This one clearly shows the external antenna and socket.  It requires using an FDTI or other approach for programming which should be acceptable since I will not be reprogramming it much if at all.  The input voltage range is not specified but it obviously has an onboard voltage regulator so I'm hopeful that it can tolerate 12VDC since I have 12VDC available for another portion of the project.  Guess I'll try the first board which I'm confident will work but may have limited range.  The new board with external antenna may be more desirable.  Thanks to all for trying to explain my range options. 

@tedbear, Interesting project.. I did go to the link site  and found that you can use the 12 Vdc -1A, but do not exceed 15 volts! I would recommend that you use a fuse on the power side. Better to be safe than sorry.. although $17 bucks isn't alot.. it's still $17 bucks...lol

Good luck on your project.

Regards,

LouisR

Hi @tedbear,

   I agree the board you have found on Aliexpress looks a better choice from the WiFi viewpoint.

  However, I fear your reliance on the onboard voltage regulator to deal with 12V might be a mistake. Looking at the photo on the web I can see 1 regulator is ..1117 type, and guess the other one is the same.

I note the description says it can accept up to 14V, and has some notes about using 9-12V, but I wonder how long-term reliable it will be at the higher voltages. My concern is that the regulator may overheat and fail prematurely.

Unfortunately, it is difficult to predict if this possible problem exists in your specific circumstances ... so I recommend set it up and cautiously monitor the temperature of the parts whilst it is operating. If one of the regulators get too hot to touch, then consider adding a pre-regulator to reduce the input voltage. Note, it will depend upon how many relays are energised at the same time and how long they remain energised. In my discussion below I assume a 'worst case' of all 4 relays energised for a period of at least a few minutes.

---------

This caution arises because:

The TTGO board I previously looked at in a photo  showed an inductor, implying a buck converter, whilst 1117 are linear regulators. Although the 1117 regulators can handle 12V voltage input for a short time, their heat dissipation capacity is limited and determined by the PCB layout. As linear regulators are essentially 'magic resistors', the heat they dissipate is the voltage drop multiplied by the current demand.

The notes on the web site suggesting a higher voltage may be required seem a bit weird. The relays shown are 5V operation and (from the data sheet) take about 90mA (each) coil current when energised (with 5V). The ESP device is 3.3V, which appears to drive a transistor for each relay. My guess is that there are two 1117 regulators, one output of 3.3V, the other 5V. The minimum input voltage is usually 1.5-2.0V above the output voltage, so assuming one is 5V output, the 'ideal' input voltage for the board is probably about 7.5V.

If all 4 relays were simultaneously energised, they will require about 360mA. If the board input is 12V, then the 5V regulator would dissipate (12-5) * 360 = 7 * 360 = 2340 mW ... which is certainly beyond the capability of a 1117. (Data sheet shows typical guide range of about 400 mW to 1400 mW, depending upon PCB layout and construction.)

Thus, you may find the regulator overheats, causing it to shutdown to try to protect itself, and typically fail permanently if repeatedly driven to over temperature. Other ESP32 cards (without relays) using the 1117 regulator have suggested a maximum of about 7V input.

Of course, I may be being overcautious, but 'cooked' voltage regulators seem to one of the most common failures in equipment I have fixed over the years. In principle, chips can run at uncomfortably high temperatures, but the downside is they have an increased failure rate ... an old 'rule of thumb' suggested each 10deg Celsius meant double the failure rate --- this implies 100deg C rise means failure rate increased by 1000 times!

Best wishes, Dave

@davee Great idea putting the buck converter in front of the Linear. Drop the 12V down to 7V with the buck sounds like a great plan. LM2596?

@zander  Thanks guys.  Actually I have another system running in another location that uses an ESP Dev board, a buck converter and an external relay board.  The buck converter handles 12VDC in to 5V for the relay board and the ESP Board where its onboard regulator drops the voltage to 3.3V for the ESP 32.  I used a Darlington array in between the ESP32 and the relay board..  This has worked fine for some time.  My concern with it is range which is tolerable.

When I saw the Lily TTgo board where this was all assembled, I thought that this might be a cleaner way to go and also pick up the ability to use an external antenna. I have now decided that the external antenna idea is not practical with the TTgo board.

The voltage overload concern may not be an issue since 3 of the relays are just used as momentary to trigger the shop door opener.  They would only be active for a second or so. The 4th relay triggers a light contactor and could be ON for a significant period of time and might cause a problem. 

The Lily TTgo board meets my desires except for the problem with an external antenna.  The latest board has an external antenna but might have issues with the voltage regulation.  I can't seem to find a board that alone covers all my bases. My plan is to try the Lily TTgo board when the weather improves.  Maybe the range will be acceptable and I will stick with it.  Otherwise I may try the forth coming board with an external buck converter to help it out on the voltage concern. These two working together should cover my concerns. 

@tedbear A WiFi extender might give you enough range if the builtin doesn't do the job., or have you thought of a mesh system?

I actually installed a mesh system in my home last month.  The purpose was to clean up dead spots for Internet access.  I set up a small "lab" in my basement and wanted to have decent Internet Access there.  The Eero base unit plugs into my modem/router and creates its own network.  The Eero satellite units are located in my dining room and basement.  I have my phones and tablets and basement computer set to the Eero network.  The upstairs office computer is still hardwired to the modem as before and uses that network. 

It might be possible to use a second mesh system to extend Internet coverage to the shop where it could be used for other purposes.  The ESP32 board controlling the door opener could then be setup in station mode rather than Access Point. Having Internet Access in the shop has not been a great desire but thanks for the idea.

@tedbear The internet doesn't have to be involved, you just want to extend the range of the WiFi radio. It doesn't care what is on the WAN port, or for that matter if there even is one. Unless you are really old like me you will assume network and internet are one in the same but it's not true, we had networks long before there was an internet. 

@zander Thanks again.  I am really old.  Yes, I'm still hung up on the extender/repeater/mesh thing in thinking that it is only for getting Internet to some dead spots.  I have an extender that I tried in my house with poor results.  I guess I should try it in my dooryard away from my house and the home network and see what happens.  Maybe it will pick up the network I created on the ESP32 board and create a companion network for it.  Later

@tedbear It won't pick it up, you will need to configure the extender to talk to the ESP32 and then be the new AP your phone or whatever will talk to. It can be fairly automatic for something like mesh hardware because the designer built in the smarts to do it, but for a simple extender where you connect to an existing AP and then present a new (stronger?) AP you have to do the configuration. IIRC there are at least 2 options, one is to have the same SSID so the phone app doesn't need to be changed, the other option is 2 different SSID's where the phone app does need to be changed. I think different SSID's is best at least in this case. 

@tedbear  Have you written the code for your application already?

Have a look at Dronebotworkshop's Getting Started With ESP32.

Where he tells you to enter your SSID...this is what determines which WiFi radio you connect to. This could be your home internet router, or a standalone router you use for a non internet LAN (local area network).

You may not need an external antenna if you park the ESP32 within line of sight with the device you are connecting with.

The first step is to determine whether the ESP32 is the source of DHCP or whether a separate router is providing it. Dynamic Host Configuration Protocol or DHCP is how the LAN provides addresses for each device on the LAN. An access point is just a device that has two halves, one half addresses the internet, and the other half addresses the LAN. Setting the ESP32 up as the access point will provide the LAN with DHCP. The advantage here is that you can connect your computer to the LAN and remotely access the LAN and perform tests and maintenance from the comfort of your arm chair.

This is also possible if you have the ESP32 connected as a device to a router. Then, instead of providing the addresses to the LAN, the ESP32 is receiving one from a router. 

The problem I see with this is that the router you use will probably be your home internet router, and will be in the house. It's radio probably cannot transmit outside of the house. This is why Ron suggests WiFi extenders and you want an external antenna.

So my long ramble here, is really trying to get you to determine what kind of network you want to set up before you worry about whether or not you need an external antenna.

Another route to go is to have your phone connect directly with the ESP32 and have a static IP address for the phone and have the ESP32 connect only to the phone. It's still using Wi-Fi but the internal antenna can be pointed at the driveway or the door entrance. I don't recommend this because there is a lot less tutorials out there on how to set static IP addresses. Once you set up the firmware in the ESP32 you run the risk of not being able to connect with it again if you have gotten it wrong.

DF

@dualfuel Thanks so much for the detailed explanation.  I have watched Bills videos about using Bluetooth and WiFi in Station and Access Point modes.  Since Internet is not available outside my home, I went the Access Point route.  I have an operating system that has worked well for 6 months.  It uses an ESP32 Dev board, a Darlington Array and a 4 relay board.  The power source is a 110VDC to 5VDC device.  This 5 VDC powers the relay board and Vin on the ESP32 board. The regulator on the ESP32 board drops this to 3.3VDC for the chip itself 

To use the system to work with the doors in the old shed, I check my phone and force it to change to the Access Point I called TedShedAP in the sketch.  I then go to the RemoteXY app on the phone or tablet and select Ted Old Shed.  This brings back a graphic with 6 buttons on it to control the doors in that building.  The only problem is I need to be relatively close to the building which is tolerable.

 I planned on doing something similar for my farm shop.  It has only one opener but it is desirable to be able to control the lights. When I saw the Lily TTgo board with relays, I thought it would meet all my requirements since it runs on 12VDC, has 4 onboard relays and I thought an external antenna. It appears that the external antenna may be possible but not without some butchering.  My current plan is to wire it into the shop when the weather improves and test the range with the internal antenna.  I'm afraid the necessary enclosure will limit the range.  If the system works but the range is a problem, I will look into another plan such as another board with an external antenna or some type of extender.

@tedbear 

Please note that the 2.4 GHz wavelength is 122 mm, and this means that a quarter wavelength is roughly one and a quarter inches long. If you keep a reflector behind your antenna an inch and a quarter you will pick up a little bit of gain from that. Also note that by moving the antenna a quarter wavelength 1 1/4" in any direction vertically or horizontally will change the reception as well.

So the idea would be to put the antenna or the device with the antenna attached roughly where you want it and start checking your reception and then move the device incrementally to see what the best reception is, and then permanently mount it. Unbelievably an inch and a quarter positional change can have a dramatic difference in your reception especially based on the fact that the antenna, on the device, is a quarter wave dipole.

@tedbear

A quick peruse though your posts leads me to think your best option is to keep things simple by just using your home network.   Where the home network does not currently reach then extend the home network as required by one of serval means.   This would have the advantage of also extending your ability to use the internet at all location just in case a future project could make use of it, or even just lounge on a garden chair near your outbuilding perusing DroneBots on your laptop sipping a nice pint of bitter.

And its really quite easy to extend your house coverage to your outbuildings.   One good way is to extend the wifi from your house to be picked up outside by means of an ethernet cable from your house router to an external arial placed on your house wall.  Something like this aerial: 

https://www.broadbandbuyer.com/products/33345-tp-link-eap225-outdoor/

Now this may be good enough to work inside an outbuilding, but this solution is really designed for garden (or beer garden) use and may not work well enough in an outbuilding. 

The very best way to get your network extended is of course to lay an ethernet cable from your house router to a hub or router in your outbuilding.   Depending on circumstances that may not be desirable, but as you only need to dig a slit trench for the cable, or run the (external grade) ethernet cable along some fencing etc. then please don't dismiss this approach out of hand as it could be easier than you think.  I managed to lay a 100 metres of cable with a bit of digging spaced out over a leisurely couple of weeks

The next choice could be a point to point wifi extender where a couple of wifi ariels point to each other and, in effect, replace the cable.  An example of these wireless building linking aerials is shown below:

https://www.broadbandbuyer.com/products/28801-ubiquiti-lbe-5ac-gen2-ptp/?gclid=CjwKCAiAvOeQBhBkEiwAxutUVK45cP-56MZqubSbxaFNMIJtToirNcLBjlS7XIPCKmEQ7MXUFM1T1RoCS3kQAvD_BwE

So a cable from you house router to the wifi aerial placed outside your house that is pointed (you have to have line of site for this option) to an aerial placed on your outbuilding, which in turn has a cable to take the signal inside the outbuilding to the outbuilding hub or router.

And of, course, as others have suggested, you could find a simple wifi extender works or may be one the the wifi mesh routers where the signal can be linked to your shed, and from there the wifi can be 'meshed' to your other outbuildings.

Hope I've not added a layer of confusion to the topic.