How to shield a live wire at 240V ?

[_q12x_]

I have a electronic board with leds (made by me) that is driving a relay. When that relay is closing it’s contacts, is actually switching the 240V for the light bulb switch in my room. This board is quite long, like 50cm (half a meter). The relay is in the left corner, and the live wires from it goes in behind the board to the hole in the wall for the mains switch. I also have a mild steel sheet behind my board that is grounded. It is shielding the interference of the 50Hz from the live wires from the wall to my sensitive circuit. But even If I have this grounded metal shield behind my board, the live wires from the relay are still affecting my entire circuit board, keeping it ON all the time. If I am disconecting the live wires from the relay, the board is functioning very well. Another IF, is if I disconnect the ground from the metal shield, the circuit board goes nuts. So the shield is doing it's job fine, but only for the live wires inside the wall !!! But not for the wires from the relay to the live switch.
- I want a way to shield these wires !
Thank you !

 

[marconi]

Thank you for the update. I have constructed the three regulated power supplies for Version 3 (+5V logic, +12V and -15V for the op amps and comparators). Now they need testing.

My progress on V3 will halt for a short while because my wife is in hospital, we have a new puppy and I have a new project starting for a client who wants to install a Ground Source Heat Pump to replace his oil fired boiler. He will soon have the solar photovoltaic panels ( 2 x 5kW systems) I mentioned before and already has a solar thermal hot water system. So some thermodynamics will occupy me rather than electronics and I will have to think about the integration of the renewable systems together.

I look forward to seeing the wireless remote IR control system in action. Rest assured I will construct Version 3 to see how well it works. I have decided to stick to the flash A-D converter method but use the strobed comparators I mentioned.

Am I allowed to know were you live to city or region level as I did with 'London'. Just adds to the 'pen pal' interest for me to look up on line and in my atlas of the world.

 

[marconi]

A guide to ground source heat pumps - Energy Saving Trust - https://energysavingtrust.org.uk/advice/ground-source-heat-pumps/

Here is a short video on GSHPs which you might like to watch - a minute or so long. There are also Air source heat pumps.

 

[_q12x_]

Good luck with the heating system project. If you need good ideas, you can talk to me as well. I can return the help.
I am from Romania - Botosani. It is a small town.
I watched your video. Basically, that system is using the heat emanated by a refrigerator to heat water for home appliances. It is a new system I am getting acquainted just now. It is interesting. It is new.

 

[_q12x_]

Many, many, thanks to mister Steve for the remote control module. If it was not him, I could not make it work so good. It's just fantastic when using it live, way batter than my imagination or than watching it in the movie.
A super update:

 

[marconi]

Good work - and pleasing to hear you are happy with your achievements.

How does the remote perform when there is sunlight or high ambient IR in the room? I am interested to know because that is what I am tackling with my Version 3. I have made slow progress this week but some nevertheless as I illustrate in the attached video which shows 5, 0, 12, -15V regulated power supplies and the 555 clock running at 25kHz to run my logic and pulse the LED sensor illuminators.

 

[_q12x_]

When is exposed to sunlight it is absolutly no problem
We take care of this problem by pulsating the signal from the remote in a band of 33 something. It is definetly not my domain. We first made it with 2x555's and then with a PIC 12f508 , basically doing the same thing the 2x555 did before but with way less components. As you could observed from the movie.
By the way, VERY COOL osciloscope you have there! Very cool. I remember you mention it to me before and it was quite cheap.
I will probably have to make a movie about how i made my remote, because like you here, I did the exact thing, I put my osciloscope to the circuit and veryfy the hell out of it until we figure out the bugs and it worked perfectly.
And yes the square wave you have on your osciloscope I have it on my "dinki" osciloscope as well, but your signal is much more cleaner and true. Mine is noisy and unclean. Its the osciloscope I use.
I will have to think to make the presentation video... phui... hard stuff. But it must be done.

 

[loz2754]

Wow! You two! 351 posts of wonderful technical wizardry. Most of which is totally above my head unfortunately.
When I was a kid I loved electronics, sometimes wish I had gone down that route...... Ah well. Keep it up!

 

[_q12x_]

Is good someone is keeping track. haha.
My latest suffering:

Q20210423 SMD Transistor Pads by q12a on DeviantArt

www.deviantart.com

Aaah.

 

[_q12x_]

 

[marconi]

As you begin to think about and design your motorised wings features, have you done a quick measurement and analysis to find out if your current power supplies can cope with the extra load when they operate?

 

[_q12x_]

As you begin to think about and design your motorised wings features, have you done a quick measurement and analysis to find out if your current power supplies can cope with the extra load when they operate?

Very good question !
But that was one of the first things I took in consideration.
My power supply that is over the door, the one that is powering the Led Wings, is marked as 5V 2A. It happens coincidentally that I just took it out yesterday and installed an indicator green led on it. Also I checked its power settings in this time so I know for sure now. I usually forget things along the way. But I know so well now because of the update yesterday.
I also took your advice and go to microchip forums and open the discuttion about PIC's there, before, when I was in trouble. They kind of helped but mostly I figure it out myself alone, and some help from mister Steve, my good american friend. He literally stay all the time near me, and poke with me this thing, until we made it work. If I was alone it would have took me much more time to figure the PIC out, but with him, I think I speed it up considerable. I work best when I have good people around me. If i'm alone, as you can see and know already, i am VERY slow. Because I am an artist, not an electrician or electronist.
I didnt think on the "movement" part very much yet. I only have 2 ideas so far. And they are complex and hard as f.a.c.
Idea #1 the wings from cardboard moving by means of memory wire (which is very expensive and I dont have it) OR my little motors I already presented, those vibrators motors I hacked.
Idea #2 a "smart" ball. Something like these image references :

And actually to follow me around, when Im walking in my room.
But this is a very complex task I might not be able to accomplish and I know it. But is a very nice idea that is on the table, as my saying is. Yah...well. I will conform to what I can do and come with better ideas than these, that are not very complex to make and realistic to make by me and my tools and components I have.
I was thinking to go on a robotics forum for this smart ball. THey might have all the hardware and software already made for such a project. I will see in the future.
For now, is just cool to imagine. Haha.

 

[_q12x_]

See? I don't lie (haha)

While doing this, I was thinking actually to your light plastic pylons. In this particular case, I really needed one. But.. is good enough as it is. THough from my other table, in the back, the angle is too wide and I can see a little dot of green, almost invisible. But this is not a big concern, im just happy I have this option installed there.
I am strongly recomanding to leave the edit option alive all the time in this forum !!!
- So, mister @marconi , did you like my PIC movie?

 

[marconi]

If it was me...... I would take one little motor and connect it to your power supply and full wings board and switch it on and off to discover ’what happens’. Put a freewheeling/fly back diode across the motor to reduce the back emf when it turns off. Might want to try at various 0 and 5 Volt tap off points to investigate volt drop effects on modules.

 

[_q12x_]

That's not even an issue. Tell me how you would make the smart ball ! That's the real issue.

 

[marconi]

q12x I thought you would like to see the shape of the voltage waveform produced by each of the four black 940nm photodiodes when they receive infra red light from the four LEDs pulsed equally on and off at 25kHz. You can clearly see the effect of the reverse biased photodiode‘s capacitive depletion layer and resistance producing a CR time constant which is too long to respond immediately to the ir light being turned very quickly on and off. You can make out the classic CR circuit charge and discharge exponential curves. One way of improving photo response time would be to increase the reverse bias which widens the depletion layer and thus reduces its capacitance thereby making the time constant shorter. The sensor array is picking up the side of the scope.

So, one might have expected nice crisp straight sided pulse outputs from the photodiode but other factors are at play causing waveform distortion.