💬 AC-DC double solid state relay module

  • Hardware Contributor

    Have we done any testing on the power circuitry here, short term tests, long term tests at all? I'm about to do the same setup as you have here in terms of the 240VAC-5VDC converting. Would love to know what your findings are.

  • And whats the best way for soldering the thermal fuse? alligator-clips for heatsink, alot of heat, wide soldering tip and fast?

  • Hardware Contributor

    Your 'board layout' image is missed the 2 resistors that you have included on the schematic (i think anyway, i can't read your schematic very well, poor resolution). I'm guessing these are not needed?

  • Hero Member

    @Samuel235 At the moment I have one board (version 3.3.1, which is missing the temperature sensor) up and running for over a week. It's in a small closed box, and it has two lamps attached to it which are powered on every evening. So far everything seems to be ok. Temperature is still low inside this box after a few hours (couldn't perform any specific measurements yet, so that's why I added the temperature sensor in this one).

    @Cliff-Karlsson I just soldered the thermal fuse really quick. But maybe some other kind of heatsink would be useful! So any suggestions are welcome for this. 🙂

    @Samuel235 I have been using DipTrace to design all my PCBs, and I must admit that the schematic view in this software kit isn't the best.. I'll see what I can do to have the schematic quality improved! But all components which are on the schematic are on the PCB, so no components are missing on the board itself.

  • Hardware Contributor

    @aproxx, I'm pleased to hear you're having no issues to date with your module!

    In that case could you point out where the two resistors are on your board before your AC power goes into the AC/DC transformer please? I'm interested in knowing why these are there 🙂

    A lot of us here use Eagle CADSOFT for our PCB and Schematic needs. It meets every requirement i can possibly imagine being needed.

  • Hero Member

    I assume you were referring to the 2 resistors at the high voltage circuit? These were actually used as placeholders for the temp cutoff and the slow blow fuse. As I didn't have these component in DipTrace I used resistors to replace them in the scheme. But I have updated the schematic to avoid any confusion!

    As for the EAGLE software: Is does meet all the needed requirements, but I just find DipTrace to be way more user-friendly.

  • Hardware Contributor


    Ahh okay, thank you for pointing this out to me. My mind can rest now haha!

  • Hardware Contributor

    Could I ask the reason for the slow blow fuse here, what is specifically drawing high current at startup? I ask because i'm attempting to make my own on board AC-DC solution and I'm very tempted to put a fast acting fuse on the other side (DC side) of the AC-DC converter. I'm not sure what would be drawing your initial current spike (if you have one). The only things i can see for you is the on board relays....

  • Hardware Contributor

    @Samuel235 Check http://forum.mysensors.org/topic/1607/safe-in-wall-ac-to-dc-transformers/295 - below post #295 is a great discussion about slow/fast blow.

  • Hardware Contributor

  • Does anyone know how to convert diptrace to kicad format? I want to try and edit to make a RFM69 version.

    An on that note - would swapping a 3.3v arduino in and connecting the HLK to raw and supply rest of circuit from the VCC pin work? That way I do not need to level shift for the RFM69 and I don't need the voltage converter either.


  • Hardware Contributor

    @sundberg84, @m26872 - Thanks for pointing me over there. I had read through those before but didn't take it all in back then as i wasn't doing my module back then. Thank you for reminding me!

  • Hardware Contributor

    Hello @aproxx I was developing something similar but using a ATMEGA328 chip, that way I would make it smaller! Can I ask you way do you use 2 100nf Capacitors after the HLK? And what is the width of the copper lines in the 220v and signal?

    Thank you
    And great work

  • Hardware Contributor

    @Soloam, the capacitors after the HLK are to filter out any noise from the HLK and the AC Input side of the circuitry. I personally shoot for a 100uF cap if its below 5A and anything over 5A i'de drop a 440uF in, along with a 0.1uF next to it. This isn't saying Aproxx is wrong or incorrect in any way, that is just my personal preference.

    As for the trace width, i can't help you on that one as i can't open any of his board files to get a reading on them. I'm sure he will provide some more detailed information for you.

  • Hardware Contributor

    I let approx answer for his width trace 🙂

    You can find online tools to calc this, plus there are different strategy like using a pcb with thicker copper (2oz but more expensive than of 1oz common). Like no soldermask so you add some solder or/and piece of copper wire to improve thickness etc..The thicker copper, the smaller the trace.

    For the capacitor, it's for filtering output ripple, not input! there is no 5A on output.
    Only 2cap can't filter everything.. but that will improve and work better than nothing 😉 And increasing a lot the 100uf like 400uf won't change things, it could be less efficient. I won't do a lesson (I'm not expert too) but sometimes its preferable to use multiple different value capacitor depending on what you want to filter. And here again there are other filtering techniques which can be used. but that's if you have problem with those ripples on your circuit and it's easier to have a scope to check how this improve.

  • Hardware Contributor

    And there is the more advanced version of my reply, thanks to @scalz.

  • Hero Member

    @Soloam I'm actually not using 2 100nF capacitors, but 1 100nF and 100 uF capacitor. Exactly for the reason that scalz mentioned. 🙂 I'm not saying these are the perfect values to use, but I came across similar values some time ago, and these give me a decent and stable voltage.

    The width of my copper traces is 2mm for the entire high voltage circuit. I have used a trade width/thickness calculator, and it should be more than sufficient to power the HLK-PM01.
    However, it is not sufficient for the traces between the relays and the connectors because it should be able to handle up to 2A (limiting factor of the solid state relays). That's why I have designed this board with open air traces between the relays and the connectors. That way it's possible to reinforce the traces with solder, after which it should be able to withstand 2 Amps.

    And good luck with designing your version of the board! If there is a way to decrease the board size even further that would be great!

  • Hardware Contributor

    Hello all, I finished my version of this idea! Thank you to @aproxx for the help! I used a ATMEGA328, this wil make it a bit cheaper. https://www.openhardware.io/view/83

    I need some help validating the layout, most important the 220v traces and the capacitors used in the layout!

    Thank you all

  • Hello,
    My question is whether the code includes support DS18B20?

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