Digital Switch between devices, please Help!

Thread Starter

Ralf Jäger

Joined Mar 29, 2018
20
Hello everyone,
I am new to this whole electronics thing and i need a bit of help. I want to have to devices running of the same power outlet but if I turn on device 1, device 2 has no power and reverse. I dont know it that is a very stupid question but all help would be greatly appreciated!
Greatings Ralf
 

shteii01

Joined Feb 19, 2010
4,644
Power outlet?
Are we talking AC like 110V at 60 Hz or 220V at 50 Hz? Or are we talking 9V DC?

Activating the switch?
Are we talking physical switch that user activates or some other electronic device activating the switch?
If some other electronic device, then what is the nature of activation signal? If analog, then what voltage/current? If digital, then what format?

As far as switching power from device to device, do you need a soft off like computers need to shutdown? In case of typical computer with hdd (spinning plates), you don't want to just turn off power abruptly because that does bad things to hdd and to flash memory devices like usb sticks. So. Some clue into the nature of the two devices that you are turning off and on is of some importance.

Welcome to hardware design where details matter.
 

Thread Starter

Ralf Jäger

Joined Mar 29, 2018
20
Power outlet?
Are we talking AC like 110V at 60 Hz or 220V at 50 Hz? Or are we talking 9V DC?

Activating the switch?
Are we talking physical switch that user activates or some other electronic device activating the switch?
If some other electronic device, then what is the nature of activation signal? If analog, then what voltage/current? If digital, then what format?

As far as switching power from device to device, do you need a soft off like computers need to shutdown? In case of typical computer with hdd (spinning plates), you don't want to just turn off power abruptly because that does bad things to hdd and to flash memory devices like usb sticks. So. Some clue into the nature of the two devices that you are turning off and on is of some importance.

Welcome to hardware design where details matter.
Thank you very much for that very detailed reply! I live in Europe so 220v AC 50Hz. I wanted to do it so that if i turn in my LED’s my lights in the living room go off. Is it possible to just wire them together (- from outlet, - from light and - from LEDs same for plus) or do you need to add a special digital switch?
Thank you,
Ralf
 

Alec_t

Joined Sep 17, 2013
11,755
If you want an 'off' position, then a 3-throw ON-OFF-ON switch would be needed: double-pole if you are switching both Line and Neutral, single-pole if switching just Line. The switch must be suitably rated for mains voltage and the anticipated load current.
 

Thread Starter

Ralf Jäger

Joined Mar 29, 2018
20
If you want an 'off' position, then a 3-throw ON-OFF-ON switch would be needed: double-pole if you are switching both Line and Neutral, single-pole if switching just Line. The switch must be suitably rated for mains voltage and the anticipated load current.
But would it be possible to have that switch in automatic. So if i turn on the leds It automatically turns of the other light?
 

Thread Starter

Ralf Jäger

Joined Mar 29, 2018
20
How will you do that? If you have to operate any switch it might as well be the change-over one.
Yea I gess, but i have the system put away in a cupboard and want to make it as easy as possible. Is there something like a SPDT switch with one imput two outputs in automatic
 

Alec_t

Joined Sep 17, 2013
11,755
Are the room lights (R) permanently wired to a mains circuit? The LED lights (L) are portable but do they have to be plugged into a mains socket?
Automatic in response to what exactly; L turning on, or R?
Which part of the mains wiring are you willing and competent to modify?
 

Thread Starter

Ralf Jäger

Joined Mar 29, 2018
20
Are the room lights (R) permanently wired to a mains circuit? The LED lights (L) are portable but do they have to be plugged into a mains socket?
Automatic in response to what exactly; L turning on, or R?
Which part of the mains wiring are you willing and competent to modify?
Hello,
R is not permanently plugged into the room lighting circuit but into the power outlet same as L. In an ideal world i would like to have it so that the lights are constantly on (exept if i unplug them) and the LEDs off. If I then turn on the LEDs with a remote the system detectes it and the lights get less or no electricity and the electricity goes to the LEDs (i live in a trailer van with solar pannels and batterys so pulling more electricity out of the outlet is not an option)
 

Thread Starter

Ralf Jäger

Joined Mar 29, 2018
20
Are the room lights (R) permanently wired to a mains circuit? The LED lights (L) are portable but do they have to be plugged into a mains socket?
Automatic in response to what exactly; L turning on, or R?
Which part of the mains wiring are you willing and competent to modify?
If i had all three wires (R,L and main) connected together (+ and - separately) and I added a timer to the lamp because i always watch tv (with the LED) at 8pm would that work? Sorry im very new to the fascinating world of electricity...
 

Alec_t

Joined Sep 17, 2013
11,755
Then it sounds like you need to activate a relay coil (or SSR) when the LEDs turn on, so that the relay contacts/output can disconnect/turn off the room lights. The devil will be in the detail of how you interface the relay coil with the remote-controlled LEDs. Relay ratings will depend on the LED circuit.

Edit: Is the 'lamp' your LED light?
 
Last edited:

Thread Starter

Ralf Jäger

Joined Mar 29, 2018
20
Then it sounds like you need to activate a relay coil (or SSR) when the LEDs turn on, so that the relay contacts/output can disconnect/turn off the room lights. The devil will be in the detail of how you interface the relay coil with the remote-controlled LEDs. Relay ratings will depend on the LED circuit.

Edit: Is the 'lamp' your LED light?
Thanks, screw that, its way above my level. If i turn off the lamp (which is not the LEDs its a desk lamp) would it be possible to then automatically switch and give power to the LEDs? Thank you for your patience
 

Alec_t

Joined Sep 17, 2013
11,755
Can you replace the lamp switch with a change-over type? If not, you would probably need a relay or SSR as already mentioned.
 

Thread Starter

Ralf Jäger

Joined Mar 29, 2018
20
Can you replace the lamp switch with a change-over type? If not, you would probably need a relay or SSR as already mentioned.
Wow, if you look in the photo below, if the lamp is off the current would directly go to the LED but if the SSR notices that the lamp needs power it takes the power, would you then also need a SSR in the power cord of the LEDs or am I messing something up here? Thank you and sorry for my lack of knowledge
 

Attachments

Thread Starter

Ralf Jäger

Joined Mar 29, 2018
20
With that setup the LEDs would get power regardless of the lamp status. Where is the LED switch?
Can you replace the lamp switch with a change-over type?
So a three way lamp switch? And does that option leave the LED power line as it is?

Edit: sorry looked up the wrong thing... how would you make the T- intersection in the image I drew, just connect all three wires (LED,light and power in)?
Thanks

Is there something like a reverse change over switch, so that it has one imput and two outputs, and if one needs electricity it automatically switches to that one?
Thank you so much dont know how to thank you for your patience
 
Last edited:

ebeowulf17

Joined Aug 12, 2014
3,274
I have a vague concept here, but none of the details. I'll try to explain and see if this helps.

I've heard too many different descriptions of the loads to be clear on what they are. LED, lamp, room lights, I'm not sure, so I'll just call it load A and load B.

Let's say load A is the one with the remote control, and the one which can essentially take the power away, only when it needs it.

So, run one leg of the power to load A through a current transformer as a means of detecting when it's drawing power. With an appropriate burden resistor and an RC filter, we can easily get a simple low voltage signal indicating whether or not load A is drawing power.

Now we run that low voltage signal through a BJT or MOSFET (maybe two, including a required logic inversion) which controls a relay that controls power to load B.

With this setup, you'd get the following:
  • Load B can be on any time (presumably still controlled with some manual switch as well,) except...
  • Any time load A is turned on (via its remote control,) the logic circuit disconnects power from load B so that only load A is on.
  • If load A is turned back off, power is automatically available to load B again.
  • Essentially load A is in control. It always takes priority.
I don't see any way for both devices to be in control, as a few of the posts above seem to suggest. However, if one load can be the master, it should be possible to make a circuit that defeats the other load any time the master load is active.

This is far more complicated than the simple DPDT relay/switch ideas others have shared, but if it turns out that the remote switching can't be tapped into, this might get the job done.
 
Top