Auto Power on/off Slave Devices When Master Is on/off

brettule on 22/03/2024 - 09:37

I've been using an Embertec SmartSwitch in my shed for years which has finally died on me. I have an old laptop hooked up to an old amp and monitor. When I power on the laptop the smart switch powers on my amp and monitor too. Music starts pumping out shortly after. When the laptop powers off the smart switch powers off the monitor and amp too. Works a treat.

Problem is, they don't make these anymore and I can't find anything else that would operate with the same function. Any thoughts on how I can achieve the auto on/off switching with another product or another method?

Cheers

Electrical & Electronics

Comments

  • websterp on 22/03/2024 - 09:47
    +2

    You can use two cheap smart sockets (i.e. Tuya based) with at least one with power monitoring and then create a simple automation to make one work as master and the other a slave. Or do the same if you can find a smart powered with individually controllable outlets.

    • brettule on 22/03/2024 - 10:14

      So I could set the slave to power on/off based the power draw required from the master?

      • geekcohen on 22/03/2024 - 10:15

        Yes. I just looked at my Tuya devices and app, can confirm you can do that. When power draw from master is greater than X, then do Y.

        • brettule on 22/03/2024 - 10:19

          excuse my ignorance, but do the Tuya devices need to be always connected to the internet to perform the logic program or do they cache the logic and can operate offline?

          • bargaino on 22/03/2024 - 11:05

            @brettule: Tuya is wifi, and nothing works without the servers in China.
            There are many possible local solutions, e.g. use the 5V power from laptop's USB port to turn on a relay.

            Monitors, for some decades now, automatically power down when they lose signal. How old is yours?
            And what sort of amp? I'm guessing the old sort with a heavy transformer that uses too much power when silent.
            e.g. does it have IR control?

            • brettule on 22/03/2024 - 11:22

              @bargaino: Yeah the monitor I care much less about, I think it does power down. The amp however is an awesome old 80's Mitsubishi DA-U300Z, no IR. It's a bit banged up but the sound it puts out is awesome and warm light comming from the VU meters makes it really cozy while I'm tinkering away in my shed. I've got a script on my laptop to shut it down after 4 hours from boot up just in case I walk out and forget to power off the lappy it will auto shut down and save the amp from unnessacary wear and tear. I want the amp to last me a few more decades yet.

              • bargaino on 22/03/2024 - 12:08
                +1

                @brettule:

                I've got a script on my laptop to shut it down after 4 hours

                Any reason you don't just use the power settings in the GUI of windows/macos/linux?

                But if you can script, you can solder, right? Actually, you don't even need that. Get a relay module, wire it inline to a short extension power cable, and connect a USB cable to turn it on. When laptop is on, 5V out turns on the relay. ( I don't know of any equivalent consumer products here.)

                If 2A is enough, use a SSR: https://core-electronics.com.au/1-channel-solid-state-relay-…
                Otherwise, https://core-electronics.com.au/5v-single-channel-relay-modu…

                • brettule on 22/03/2024 - 13:34

                  @bargaino: My setup is all triggered around an old bakelight pull switch. Ya know those ceiling mounted switches with a pull cord? When I yank on that, power is delivered to the master device, my laptop. The laptop BIOS is set to auto power on when it detects power input, so the laptop boots. The Embertech senses the power draw on the master and powers on the slaves (amp and monitor). Once the laptop boots a simple script runs that begins the 4 hour timer to shutdown.

                  If I want to power everything off earlier, I just yank on the pull cord again. This cuts power to the laptop, I've set the laptop to perform a shutdown whenever it's on battery. Meanwhile the Embertech senses the master is no longer drawing power so it cuts power to the slaves (amp and monitor).

                  It has been working quite well until the Embertech died. I can solder, sure, but I've not played around with relays on 240v before.The relay you linked, that will cut and resume 240v based on if there is 5v active or not on the other side?

                  • bargaino on 22/03/2024 - 14:35
                    +2

                    @brettule: Yes, I'm not sure about the solid state ones, but the old type is simple, will work if wired to a USB cable.

                    Simplest way is to get a short extension cable, strip some insulation, cut the live wire (only) and connect to relay, common and N.O.
                    To make it secure, put all that in a box with cable ties for strain relief. Say a Junction Box from bunnings.

                    If not confident, get someone to check it. And of course, leave fixed wiring to the experts. ie only touch things that plug in.

                    • brettule on 22/03/2024 - 14:52

                      @bargaino: Sweet. Great advice. Thanks.

                    • brettule on 16/05/2024 - 15:26
                      +1

                      @bargaino: I picked up a second hand Embertec and was using that for a few months, but that died too, so I decided to go the route you reccomended. It worked a treat! I used the solid state relay one you linked to. Pretty simple to wire it all up using spare USB cable and ext lead, mounted in a nice little box and named it the USB Power Switcher 2000, all written in 80s computer font. Perfection.

                      Thanks again @bargaino

                      • bargaino on 16/05/2024 - 15:36

                        @brettule: Awesome! Thanks for the feedback. Any chance of a photo? :)

                        • brettule on 17/05/2024 - 07:41

                          @bargaino: Here you go. Not got its name on it yet. https://imgur.com/a/xAb9r7s

                          • bargaino on 17/05/2024 - 10:54

                            @brettule: Thanks. Very professional!

                          • petestrash on 28/05/2024 - 23:53

                            @brettule: Nice Job, and a cheap replacement. I just note there is no fusing to prevent the 2A SSR being overloaded. If you're not going to put a fuse inline, maybe mark the box with "2A MAX" in case you forget, and want to reuse it for something else in the future and think it's 10A.

                            • brettule on 29/05/2024 - 07:00

                              @petestrash: The description says "output with resistance fuse 240ACV/2A", does that not mean it has a 2amp fuse built in?

                              • petestrash on 29/05/2024 - 23:20

                                @brettule: Looking better at the tracks below the PCB, the green component could be a fuse, but I can't read the details from it in your photos.

          • geekcohen on 22/03/2024 - 11:08

            @brettule: Require WiFi and always to be connected. It is all internet based. No internet, doesn't work.

  • JimmyF on 22/03/2024 - 12:49

    I've been using an Embertec SmartSwitch in my shed for years which has finally died on me.

    Same…. I turn on my PC and everything else follows, screens, speakers, lights etc.

    The best place to find them is ebay or marketplace.

    Otherwise you can buy them new still

    $99 from the maker https://embertec.com.au/buy/buy-now/

    or $29 from here https://www.thesoundlab.com.au/products/embertec-smartswitch…

    • brettule on 22/03/2024 - 13:13

      The $30 link is sold out. I thought I read somewhere around here that the Embertec devices are prone to failure becuase of the way they do the voltage switching.

      • JimmyF on 22/03/2024 - 14:18

        I believe there is a design flaw with them. I'm on my 'backup' one. I got two when they offered them for free ages ago. After many years the first one stopped turning on/off the slave port for some reason. Didn't look into it much, as I had a spare.

        Not sure if they are fixable or not. You could try opening it up and seeing if anything jumps out at you.

        But there are a heap on eBay for sale at random prices. Like 3 used ones for sale for under $50 shipped.

        https://www.ebay.com.au/itm/145669784058

        or 3 new ones for $60 shipped

        https://www.ebay.com.au/itm/13478485518

  • spurf on 23/03/2024 - 11:19

    Smart Standby Power Controllers with Surge/Overload Protection | Emerald Planet https://amzn.asia/d/9txcKW9

    • brettule on 25/03/2024 - 09:16

      It says this power board has automatic power off after an hour, that's going to annoy me. I want to control when and how the devices power off.

  • pjetson on 23/03/2024 - 12:25

    Can laptops be configured to turn on when power is applied? I've never looked for that in the bios. Anyway, if they can, couldn't you just use a powerboard with a single switch on it to turn everything on and off at the same time?

    • brettule on 25/03/2024 - 09:14

      Not all BIOS support booting with a resumption of power, the trusty old HP I'm using does. I'm looking for any device, including a powerboard, that can turn everything on and off at the same time. Do you know where I can find one?

      • pjetson on 25/03/2024 - 13:15

        If you turn on this option in your BIOS, then your laptop will boot when the power is turned on. If you use a powerboard with a master power switch, and plug the laptop and all your other devices into that same power board, everything will turn on and off together with that one master switch. You'd still need to shut down your laptop properly.

        Here's an $8 powerboard with a master switch https://www.bunnings.com.au/click-white-4-outlet-powerboard-…

        I use a similar device to (manually) turn on and off with a single switch my TV and all the associated devices connected to it.

        • brettule on 25/03/2024 - 15:02

          Gotcha. How do you turn on/off the powerboard, is it that big red button?

          The problem is that I need the master device to control the slave devices. That's because I have the laptop always powering off after 4hrs which in turn powers off the amp to protect the beautiful old amp from running until I notice next time I walk into the shed.

          • pjetson on 25/03/2024 - 16:45

            @brettule:

            is it that big red button

            It's a switch, not a button, but yes, it's how you turn the power board off and on.

            That one is not the only power board with such a switch, but you wanted a link and it's the first one that I found online.

  • petestrash on 26/03/2024 - 18:22

    I have a few of these around the house, I am surprised they are so uncommon now.

    They are generally known as master slave power boards.

    Here is a few I have found
    https://www.wagneronline.com.au/master-slave-switch/ac-power…
    https://www.bournesuperstore.com.au/5-way-energy-saving-mast…
    https://www.scribblygum.com.au/electrical/power-boards?produ…

  • JimmyF on 05/04/2024 - 11:21

    Still looking for one? $5 https://www.facebook.com/marketplace/item/370564925821833

    • brettule on 05/04/2024 - 11:36

      Thanks. I need the PC model not the AV unit.

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