Antennas

@davee I thought they were mechanical relays.  <<<< OOPS, ignore that comment.

Hi @tedbear,

I observed that some other relay boards use an opto-isolator to handle the voltage level shifting.

Maybe you saw one with 'solid state relays'. This is a long established misnomer (back to late-1960s/early'70s if my memory cell is still working)  ... in which the power switching device is solid state ... typically triac, thyristor, FET, etc. These often need to be opto-coupled to the control inputs for safety reasons.

The name was coined to make it sound like a direct 'drop-in' replacement for electro-mechanical relays -- rather like you may have an SSD - solid-state drive in your PC, which has no moving parts and hence is not really a drive at all .. it is a type of non volatile memory.

Whilst I would need put a saw through the grey cubes on your board to prove it, I am pretty confident that the board you have referenced is an 'old-skool' relay board, with 'real relays'. The nice thing with relays is that, subject to the insulation being adequate, there is no connection between the coil and the relay contacts, so the drive and power circuits are naturally isolated from each other, unlike their solid state cousins, unless they have optical drive mechanism deliberately built in.

Best wishes,

Dave

@davee Dave to the rescue, that's the proper explanation, ignore the man behind the curtain (me) above. 😀 

Thanks to both of you.  My knowledge is quite limited which should be obvious by now.  I did manage to get the zip file downloaded and unzipped.  It did notice a schematic which showed an old school relay being triggered by a transistor and what I guess is called a flyback diode to dissipate the EMF when the relay is released.  I didn't find any reference to the GPIO pins that Davee mentions but they certainly seem reasonable as some are the same as the other ESP32 board I have used.  I'll likely have more questions which is your reward for being so helpful.  I should be able to give the project a try soon.

Hi @tedbear,

RE:

I didn't find any reference to the GPIO pins that Davee mentions

   If you found the schematic pdf, I mentioned, look to the block in the top left, labelled ESP-32S.

   The pins on the right side of the block IO16, IO17, IO18, and IO19 goto CTRL1, CTRL2,CTRL3 and CTRL4

  Then look to the relays and their coil drive FETs ... CTRL1 is the gate drive for the FET Q1, and so on for CTRLs 2, 3 and 4.

Let me know if you can follow it now.

Best wishes, Dave

@davee I see it now. I didn't follow the Control lines to the ESP.

Hi @tedbear,

  I understand ... in the 'old days' schematic lines tried to reach their destination. Part of the art was drawing a schematic that could be followed without getting tied up in knots.

Unfortunately that can get messy with computer busses that connect to almost every chip, so people got used to connecting them by labels.

Now, it seems to have gone to the other extreme, with components splattered on to a page, or 20 pages, and nothing connected by lines, so you spend ages wondering how many ends wire XYZ122 has in a 20 page schematic. That's progress. 😀 

Hope you are 'Good to go' with your project ... at least when you have found a younger person or a new set of pliers...

Best wishes,

Dave

@davee I couldn't resist. 'He worked it out with a pencil'

Success.  I have been attempting to use my latest ESP32 board for a project.  It has 4 relays and an external antenna.  It does not have a USB connector but does have a screw connector and/or plug for external power.  It has 5 pins on a header for programming. There would be several ways these pins could be used with another device such as an FTDI.

The board I received is not identical to the one in the documentation since they added a momentary Download and Reset button.  In the past this needed to be done via two of the pins on the header via a loose wire for the Download and Reset that were literally touched to ground.  The added switches make using the loose wires unnecessary.

The Tx, Rx and Ground pins of the header are needed for programming.  I have a programming module that came with my ESP32 CAM kit.  I thought I should be able to use jumpers from its Rx, Tx and ground to connect to the new board.

Thanks to Davee for researching the board and informing me that GPIO Pins 16-19 are used to trigger the relays. I was able to download a copy of the schematic where this is clearly shown as well as the 5 header pins for programming. No other GPIO pins are brought out which would somewhat limit the usefulness of this board.  fortunately I don't need any more pins for this project.  I have another somewhat similar relay board that has some solder pads for some other GPIO pins. That board did not have an external antenna socket which I desired for better range of the Wi-Fi.

I tried several times to load a simple blink sketch figuring that I should be able to hear the selected relay click ON/OFF.  I was not able to get the Arduino IDE to load even a simple sketch.

After some research today, I determined that my approach to using the Download and Reset buttons was incorrect.  After the program has successfully compiled and the IDE is ready to download I need to: 1) Push and Hold the Download button 2) Push and release the the Reset button while continuing to hold the Download button in 3) Release the Download button.  The download process then begins.

My first attempt was to use a modified blink program with output set to GPIO 16 with a 2 second delay.  I could hear the relay click and by testing continuity between the Common and NO or NC terminals of the relay confirmed that the sketch was controlling Relay 1.  I changed the sketch to use Pin 17 and repeated the process which tested as expected for Relay 2.  I repeated this using GPIO 18 & 19 which we successful also.

I then used my sketch which uses a Wi-Fi Access Point and an app on my phone to control the relays.  This is the sketch shown above.  This seemed to work and I was able to confirm the desired action on the relay outputs.  It is now a matter of placing it in an enclosure and mounting it on my shop and then wiring the relays to the 3 button switch box for the door opener and a contactor to work with the lights. 

This should allow me to use my phone and/or tablet to control UP, DOWN, STOP on the shop door and toggle the lights.  All these functions can still be handled by the original 3 button opener and lights which I rewired with a 3-way switch and contactor.

Thanks to Davee and Ron for their help, you were kink and informative.  I resisted asking questions on some of the other forums since many posters seem to enjoy poking fun at the less experienced.  I agree that one needs to do his own research and not just expect someone to do it for them but one gets to a point where frustration sets in.  Thanks to all.

@tedbear Glad to hear you got what you wanted, but if it was me, I would have got a 'normal' ESP32 board and a 'normal' relay board. It sounds like they cobbled together your combination board in a non-standard way. I am sure glad you figured it out so we didn't have to attempt long distance debugging.

Actually I did just that with the door opener in an old shed.  I used a more common ESP32 Dev board, a separate relay board and a Darlington array to interface the GPIO pins which I chose to use to the relay board. I also needed a 110VAC to 5VDC adapter.   I needed 6 outputs so I used an 8 relay board I had on hand.  This actually works fine although I need to be fairly close since I'm using the ESP32 in Access Point mode.  

The other building only needed four relays and I found a board that contained four relays and what I thought was external antenna capable.  That board has a USB connector and programmed nicely.  However it does not have an ipex connector for an external antenna.

I then noticed this last board kit which contained the board, an ESP32 WROOM-U and external antenna.  I thought this would be perfect for my other building project.  This board is connected to its relays but no other GPIO pins are available.  Maybe GPIO 0 could be used.  However this is not a problem with this project.  The trick to loading this ESP32 is to hold down the momentary switch labelled Download that shorts GPIO 0 to ground and while holding it, cycle the momentary labelled reset.  Then release the Download pin.  This is the part that is somewhat different than my other ESP32 boards. 

Again thanks for the help and interest. 

@tedbear Good to hear you are making progress.

I'm finally to the point where I'm going to install my ESP32 relay board in a plastic enclosure on the outside of my shop.  I will also install one on the outside of another older shed.  The boards I purchased have external antennas.  I will be using the ESP32s in the Soft Access Point mode since I do not have internet access at these locations. The purpose of the ESP32 boards is to control the door openers and lights in the buildings from a phone app.  Having good range is highly desirable.  I am now wondering about the placement of the external antennas.  It will be easy to drill a small hole in the enclosures.  I'm wondering if the placement will have any effect on the range.  I could mount the antennas on the outside front face of the enclosures, on the side or on the top or bottom.  My fear is possible interference due to possible "reflection" off the metal siding on the building since some locations would place the antenna close to the steel.  I don't want to drill a buch of holes for a trial & error test.  Maybe it won't matter.  TIA.

@tedbear I don't KNOW if it matters, but even with a good quality router with multiple antennas I always was told to place one horizontal, and one vertical. If possible a trial and error approach is likely your best approach. I don't know what kind of external antenna you have but mine can swivel to almost any orientation.

Thanks for the quick reply. This forced me to think a bit more.  The external antennas that I will use came with the boards and are identical to the black stub antennas on my router and wireless cameras.  Since the front covers of my enclosures are symmetrical, the covers can be attached in four different rotations.  By drilling my antenna hole off center towards one edge, I could try the four possible rotations to see if one seems better than the others.  I suspect there won't be much difference. I can drive up to the door and stop within range but having greater range would be handy.