💬 RFM69 Livolo 2 channels 1 way EU switch(VL-C700X-1 Ver: B8)
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Hi @mtiutiu - Firstly nice work. I bought a few and sent on a little gratitude also.
Is there a revision or something on the lenovo switches to make sure that I have the right one? I have quite a few now and a few more on the way so I just want to make sure I am all set.
Thanks!
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@mtiutiu Thanks for the quick response, can only eat PCBs without components? I can not make a PCB.
Few weeks ago I uploaded and shared to Oshpark pcb web service this @mtiutiu pcb design (but take care !!! I think this is not last one version @mtiutiu design), so anyone can easily find it there and order build some pcb if like.
You can check it at https://oshpark.com/shared_projects , and easyly find it with only enter "livolo" word in the search case.
Sadly I don't have enough time yet to involve more in this project, but in near future I'm going to that and test that awesome design that this project have.
Regards
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@jirm The differences between the hw designs that I made are very small and have no impact regarding the final functionality of the board(the OSHpark version is ok too). The biggest change was to trim down a little bit the round corners of the board so that it fits from the start inside the switch case(otherwise you need to use some abrasive paper to trim it a little bit - but not much). I also added a ferrite bead to filter high frequency noise that may come from the dc-dc switching power supply and replaced the important filtering capacitors with tantalum ones(but the old board revision model can be used also to solder 0805 type tantalum caps as the footprints are large enough).
@shabba VL-C700X-1 Ver: B8 is the hw revision of the Livolo switches that I have. But this is marked on the power/relays board from inside and not on the enclosure. So in other words you can see that revision only if you open the switch. Otherwise it's impossible to say as the Livolo manufacturer sells it using the same model number(like VL-C702 or something like that) but the hw revision can be different and can only be seen inside the switch. You can see the board that I have by inspecting the pictures posted on the project page.
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Few weeks ago I uploaded and shared to Oshpark pcb web service this @mtiutiu pcb design (but take care !!! I think this is not last one version @mtiutiu design), so anyone can easily find it there and order build some pcb if like.
You can check it at https://oshpark.com/shared_projects , and easyly find it with only enter "livolo" word in the search case.
Sadly I don't have enough time yet to involve more in this project, but in near future I'm going to that and test that awesome design that this project have.
Regards
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Crap! I have version C2. I have already ordered all the BOM components! Doh.
Can the old PCB be hacked into working with this? What is the actual difference?
Thanks!
Can you post some pictures of the new board? I'm curious how it looks on both sides. I'm referring to the power/relays board underneath. I may need to recreate this project board after the new one because my friend for whom I made this project initially bought the new version of the Livolo switches. So in the end I think I'll work on the new version but only after he receives the switches as I need to compare and see the differences from both a mechanical and electrical point of view.
Don't worry about the BOM as that part stays the same. What could change is only the PCB layout and its size and/or outline. -
Shared album here: https://goo.gl/photos/H5w7u9cNbiS6SGRD9
Can you focus a little bit better on the power/relays board? Those pics are a little bit blurry. Thanks. Oh..and I almost forgot - thank you for your gratitude.
The main change is that they added a 2x7 connector now instead of the old one which was 2x6. But that's not a big problem at all as I can recreate the PCB to accommodate the new one. Still I have to wait for the Livolo switches to come in my hand so that I can identify the changes regarding the new connector(where the relays are connected and the 12-14V line if any). Other than that I don't see any big changes only the rounded corners are not so round now and they have a cut. The MOSFET is placed now at a 45 degree angle and the relays driving IC is a TSSOP one if I see well in the pictures. The 3.3V or 3V regulator is placed somewhere else now but that doesn't matter as I don't need it.
So in short: I need to recreate the PCB to accommodate the new 2x7 connector and to add cuts in the corners. BOM will not change.
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Can you focus a little bit better on the power/relays board? Those pics are a little bit blurry. Thanks. Oh..and I almost forgot - thank you for your gratitude.
The main change is that they added a 2x7 connector now instead of the old one which was 2x6. But that's not a big problem at all as I can recreate the PCB to accommodate the new one. Still I have to wait for the Livolo switches to come in my hand so that I can identify the changes regarding the new connector(where the relays are connected and the 12-14V line if any). Other than that I don't see any big changes only the rounded corners are not so round now and they have a cut. The MOSFET is placed now at a 45 degree angle and the relays driving IC is a TSSOP one if I see well in the pictures. The 3.3V or 3V regulator is placed somewhere else now but that doesn't matter as I don't need it.
So in short: I need to recreate the PCB to accommodate the new 2x7 connector and to add cuts in the corners. BOM will not change.
@mtiutiu It's the PCB that i made here : https://github.com/tonnerre33/Linovo_EU_2Gang_1way/tree/develop/
You can take many informations that you want ;)
I'm curious to see how you'll do the pcb for compare with mine and learn ;) -
@mtiutiu It's the PCB that i made here : https://github.com/tonnerre33/Linovo_EU_2Gang_1way/tree/develop/
You can take many informations that you want ;)
I'm curious to see how you'll do the pcb for compare with mine and learn ;)@tonnerre33 Great work. Can design with esp8266, it would be fine
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@mtiutiu It's the PCB that i made here : https://github.com/tonnerre33/Linovo_EU_2Gang_1way/tree/develop/
You can take many informations that you want ;)
I'm curious to see how you'll do the pcb for compare with mine and learn ;)@tonnerre33
Nice work. I will steal maybe the outline of the board(board frame) :simple_smile: . Did you tested it from a mechanical point of view? I mean will the board fit in the enclosure? And I see that you use the existent voltage regulator from the Livolo power/relays board...I didn't wanted to use that because the voltage drop over it is pretty big(12-14V - 3V =~ 9-11V) and with that in mind considering the TX current of the RFM69 which is around 50mA gives a max power dissipation of: 11V x 50mA = 550mW - pretty high(I didn't added here the MCU, LEDS and other stuff). Now this only happens on TX time which should be pretty short in theory so it should handle that(but better check the voltage regulator datasheet though). Rest of the time it will be around 16mA(RX current of the RFM69W) + a few milliamps for the MCU and other components - around 20mA let's say and this translates to: 11V x 20mA = 220mW(half power dissipation compared to TX mode).Now depending on how much time you're in TX mode compared to RX mode this will be around 300mW maybe if we take the average(but this is just a rough estimation). The onboard regulator that they use is a Holtek 7130-1 device which can whitstand a 24V input voltage BUT only 30mA output current max and it can dissipate using the SOT89 package around 500mW maximum so it may heat.
I don't know if on the current board they changed it or not but still imho it's not a good idea on the long term to overload it. Indeed if the average power dissipation doesn't reach that value(500mW) it's ok and you should stay below that: usually it's a good idea to dissipate half of the max allowed power only.And I saw that the 3V voltage regulator powers other stuff on the relays board not only the front plate so we should take that into consideration too.
Given all of the above and thinking on the long term that's the main reason I used a DC-DC step down converter powered from the 12-14V line which is also the voltage used to power the onboard 3V regulator that Livolo uses.
Most of the problems(if not all) come from a bad designed power supply. It seems that most people underestimate this part but what they don't realize is that the power supply is the most important part of every circuit and that it plays a very important role regarding the final performances and stability of the whole circuit that it powers.
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Thx mtiutiu.
I followed your advises and i converted the project to kicad ;)
For the board frame, i have tested it with paper but it's difficult to check it because paper is flexible..Same for the position of the 2x7 pins connectors, i think it's ok but i'm not sure until i have tested it with a real pcb.
You are right for the power !! I haven't check the current consumption of the RFM !! OMG 45mA in tranmit mode when NRF24L01 is 11.3mA (but with 0dBm output power for NRF).
For RFM it's 20mA with 0dBm. Can't we set RFM to 0dBm ? I don't know the consequences for the range if we change this parameter...
The installed regulator is 7130-1 = 30mA for Vin=5V. Maybe it's more current for 3V ? I didn't see the information in the doc :(
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Thx mtiutiu.
I followed your advises and i converted the project to kicad ;)
For the board frame, i have tested it with paper but it's difficult to check it because paper is flexible..Same for the position of the 2x7 pins connectors, i think it's ok but i'm not sure until i have tested it with a real pcb.
You are right for the power !! I haven't check the current consumption of the RFM !! OMG 45mA in tranmit mode when NRF24L01 is 11.3mA (but with 0dBm output power for NRF).
For RFM it's 20mA with 0dBm. Can't we set RFM to 0dBm ? I don't know the consequences for the range if we change this parameter...
The installed regulator is 7130-1 = 30mA for Vin=5V. Maybe it's more current for 3V ? I didn't see the information in the doc :(
If you keep the average power dissipation under 250mW(half of the max rated value from the datasheet) it should be ok. Reducing the Tx power helps but will decrease coverage - but that's not a problem if you set your nodes as repeaters too as this will increase coverage(not the battery powered ones of course). So yes there are solutions don't worry.
Oh and I used paper too when I replicated the original board outline, touchpads and main connector placement. Then I scanned it, imported it into Inkscape, a little bit of QCAD...and in the end got the final results. There may be an easier way of doing it but I didn't had any better idea(s) at that time.
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That device is rated at 16V max input voltage...I won't use that because the input varies from 12 to 14V approx. So it's like living on the edge. Why are people afraid of including a DC-DC converter into their design when high voltage drops are involved and a little bit more output current is required - actually we can speak in terms of power here as it's more appropriate. So we all know that when it comes to more power a DC-DC converter is more efficient than a classic LDO. Is it because of noise? That can be filtered not a problem and reduced to an acceptable level. In terms of volume - indeed there are more components involved and a little bit more care is needed when designing the PCB but hey we need to make some compromise in the end...and I for example like to stay on the safe side on the long term.
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That device is rated at 16V max input voltage...I won't use that because the input varies from 12 to 14V approx. So it's like living on the edge. Why are people afraid of including a DC-DC converter into their design when high voltage drops are involved and a little bit more output current is required - actually we can speak in terms of power here as it's more appropriate. So we all know that when it comes to more power a DC-DC converter is more efficient than a classic LDO. Is it because of noise? That can be filtered not a problem and reduced to an acceptable level. In terms of volume - indeed there are more components involved and a little bit more care is needed when designing the PCB but hey we need to make some compromise in the end...and I for example like to stay on the safe side on the long term.
