PS_ON Circuit - Please Review (and correct if needed)



  • Hi,

    I've designed a simple SSR-based circuit in order to utilize the PS_ON pin functionality of the Duet Wifi with a non-ATX 24Vdc power supply (see below).

    First let me note that If this was any other DC circuit, I'd just get the parts and breadboard the whole thing, but as AC Mains play a big part here, I want to make sure I haven't made any silly mistakes and/or overlooked anything important.

    [h]Intro
    [/h]

    The aim of this circuit is to allow the user to turn the printer on/off via the PanelDuo touch screen.

    For this purpose, the circuit includes an AC-DC converter with a 5Vdc output to feed the Duet-Wifi with continuous low power, and an SSR for controlling the 24Vdc power supply which also feeds into the Duet-Wifi.

    Also note that I haven't included a fly-back diode to protect the PS_ON pin as it appears that this isn't necessary when using an SSR (as opposed to a conventional relay).

    [h]Schematics
    [/h]

    (I've tried embedding the circuit's schematics directly in this post, but couldn't figure out how to do it - if anyone could please tell me I'dll happily update accordingly 🙂

    https://drive.google.com/file/d/1Fbm6pvi5CAfrJVpQgBxvfg_yfOIxbycH/view

    For PDF format of the schematics see:
    https://drive.google.com/file/d/1LdYS3_6BEe5lKoALidmS5rl6_SgN82VV/view?usp=sharing

    [h]List of Parts[/h]
    https://drive.google.com/file/d/1kAf8v5YtqoIqN-tXIPrrOFWevskoasno/view

    For convenience, the full list of parts, including links to the product listings & datasheets, can be found here:

    List of Parts (XLS): https://drive.google.com/file/d/1rypE_FQnSDghgUUxQopIrTzR8eWKQ8OB/view?usp=sharing

    [h]Critical Review[/h]
    Given all this, I'd greatly appreciate it if members with a critical eye and experience with AC and/or the PS_ON functionality tell me if this circuit is valid or should be corrected in some way.

    Moreover, any advice or suggestion about this circuit, including how it might be improved by adding additional safety features (or any other feature for that matter), would be very much welcome.

    [h]Open Source[/h]
    Just to note that, once verification that the circuit is correct has been obtained, I'll upload the Eagle schematics and all other relevant docs to my GitHub so everyone could have access to the complete info.

    [h]Related Discussions[/h]
    I've done my research prior to creating this thread and indeed found similar discussions on this topic. However, these discussions seem to contain only verbal descriptions and/or rough sketches of the circuit & parts used, and as I noted above, I'd like to make absolutely sure I'm going the right way about it before putting it together and turning the power switch on.

    In case those other discussions are of interest to anyone, see:
    https://www.duet3d.com/forum/thread.php?id=2173
    https://www.duet3d.com/forum/thread.php?id=511
    https://www.duet3d.com/forum/thread.php?id=553

    Thank you very much in advance,
    SnowCrash


  • administrators

    I didn't spot anything wrong with the schematic, although I didn't look up all the part numbers.

    You might want to use an IEC power inlet connector complete with switch, indicator light and the fuse, similar to https://www.ebay.co.uk/itm/Fused-and-Switched-IEC-C14-Mains-Inlet-with-Red-Neon-DPST/141925607113.



  • @dc42:

    I didn't spot anything wrong with the schematic, although I didn't look up all the part numbers.

    Thanks, dc42! I feel much more confident about building the circuit now 🙂

    @dc42:

    You might want to use an IEC power inlet connector complete with switch, indicator light and the fuse, similar to https://www.ebay.co.uk/itm/Fused-and-Switched-IEC-C14-Mains-Inlet-with-Red-Neon-DPST/141925607113.

    I already am 🙂

    That's where the ceramic fuse (F1) is sitting, though you're right that I didn't include that fact explicitly in the schematics.

    Just For reference, the part I plan using is Schurter's KM01.1205.11 with 4301.1405

    https://uk.rs-online.com/web/p/iec-connectors/4982631
    https://uk.rs-online.com/web/p/fuse-blocks/4982653/

    One follow-up question if I may:

    It occurred to me that it might be a good idea to have the circuit include terminals for a general emergency stop button.

    However, I've got no clue as to:

    (1) If it's indeed a good idea
    (2) What type of switch is appropriate
    (3) How to hook it up within the current circuit

    Any suggestions/guidance you (or any other knowledgable member) could give me on this?

    Thanks again!
    SnowCrash



  • Emergency stop: https://www.princessauto.com/en/detail/emergency-stop-switch/A-p0700322e

    Big mushroom style plunger button mounted somewhere easily reachable.

    I look forward to seeing this circuit built and tested. I'd like to be able to do the same eventually.



  • @Phaedrux:

    Emergency stop: https://www.princessauto.com/en/detail/emergency-stop-switch/A-p0700322e

    Big mushroom style plunger button mounted somewhere easily reachable.

    I look forward to seeing this circuit built and tested. I'd like to be able to do the same eventually.

    Thanks for the input, Phaedrux!

    Nevertheless, I've thought about the emergency button some more and realized it's not really needed.

    As noted in a previous post, I'm planing on using a switched AC inlet module and that switch is effectively fulfilling the role of an emergency stop button in the best way, that is, it cuts off all power to the printer on the AC side.

    Hence, if there are no more comments/corrections from anyone, I'll move forward to finalizing the PCB design and post everything on GitHub once done.

    SnowCrash


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