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]

Perhaps it is a good time to take a break from the wings project, do something completely different and then return to it a little while later with a fresh mind?

 

[marconi]

I suspect - knowing you a little better after 271 posts (!) - you will carry on

Would you do one test for me in absolutely the way I describe? Make up a 6 Volt battery and use this to power your wings circuitry instead of the 5V power supply. Completely disconnect the 5V mains power supply (top left of your wings board) and unplug it from the socket. I would like to see how the modules behave when powered by a pure continuous direct current not derived from the mains supply. Four AA batteries should do the trick - four Cs or Ds even better.

 

[marconi]

Solving problems is what engineers like you and me and countless others do to have fun. I hope you like the latest motivating poster to go on the wall in your laboratory.

 

[_q12x_]

I suspect - knowing you a little better after 271 posts (!) - you will carry on

Would you do one test for me in absolutely the way I describe? Make up a 6 Volt battery and use this to power your wings circuitry instead of the 5V power supply. Completely disconnect the 5V mains power supply (top left of your wings board) and unplug it from the socket. I would like to see how the modules behave when powered by a pure continuous direct current not derived from the mains supply. Four AA batteries should do the trick - four Cs or Ds even better.

Thank you for your trust and for knowing me !
And indeed I will not give up. Thank you for your trust so far !
I was thinkin on power it up more than 5V myself as well, andI also remember you suggesting me to do it as well, some times before.
I can not do what you ask me, because I'm afraid of damage it. I did a ton of tests so far, on the breadboard, and right at this moment, is working excellent on 5V. It is drawing a very low current of 30mA to 60mA, the entire board ! I'm affraid of damage it or disturb it's normal functionality, irreversibly and I did work for it a ton of time just to experiment so drastically at this point in time. I've already made a test with my american friend, by connecting the pin9 to +5V and indeed all the leds are lit FullY ! , but... the current is way over my expectations, was around 150 to 200mA. So I revert it back to my usual way of functionality which is dimmer but quite visible and it is not blinding me when in use, that's one of my points keeping the leds at a dimmer intensity. Also probably a major modification in the design itself and component count and values- for example: adding a resistor for each led in the wing, who knows. If that will get me the best functionality of it, then I will do it, but this as a possible example, and not in plan to do it now, haha.
I also have that 5V power supply mounted on the wall, though is not a terrible reason for that alone, but it counts as one.
In the future ! (tada-tadaaaa) , I plan to probably make another wing. THis one here is a prototype how I though alone to make it with my own head, and I admit I have mistakes in it. But I plan to make it with an engineer or someone way better than me, who can seriously make it run at it's full potential/randament with full brightness, with brightness variation, with sensing variation perhaps, all the things I could not resolve right now but it is functional as it is so I can't operate it from this point.
I hope you understand my reasons, and not insist on it. Some things I can do, some I can not. Thank you for your support.

 

[marconi]

The final decision on the way ahead is down to you as the chief engineer of this project.

Here are there reasons why I know using a 6V battery will cause no harm to your modules:

1. As soon as current is drawn from the 6V battery it’s terminal voltage will drop because it has internal resistance;

2. For non of your modules or parts of your modules is the supply voltage of exactly 5V critical. An increase to just over 5V but not more than 6V will not damage anything.

3. There is most likely already more voltage variation already from the 5V mains powered dc supply. Is it a regulated or stabilised power supply maintaining 5V? To what tolerance? Is it providing 5V whatever the current? Have you monitored it?

I understand your caution.

The dc from a battery is pure direct current. The dc from the power supply has ripple, some ac mains superimposed and if it is a switched mode power supply then some harmonics of this conversion process. And on top of all these there is the electrical noise conducted between the mains and 5V because of imperfect insulation.

But do not be pressured by me. Do what you feel comfortable with since it is your project.

 

[_q12x_]

- Give me your best IR remote circuit that you can think of/know of, and that is working optimal at least 4meter distance.
It's the next thing I really want to try. My reason and my desire is to use multiple (probably 2)remotes with a IR led.
I suspected the RF boards will be problematic but now I know why ! That is called experience, even if it failed on me.
Can you help me on that?
Oh...and if it helps you in any way. my american friend had build (not like you) only the RF transmission + the 555 circuits for both Tx and Rx. For him it worked perfectly. But for me it did not. My point is that even if its working for you there, is not necessarily to work for me the same. Ive already experienced it and im telling you to know how things are. Another point I want to make with this example i mention, is that we must try it until it works, because if we try enough times, it will work. Im talking about the IR experiment we are about to make.
Im thinking to start making my own design but.... im really new to it, so Ill handle it to you first.
This circuit I found the other days. I want to believe it will behave the best and in my parameters I want it as I enunciate it at the start of this new post here.
If you have your own design, Im happy to see it. I kind of finding this circuit, that is a bit hard because of the double power supply I must insert, and I very much want to avoid that. And also at 5V, and not at 12V as this is offering.
But if no alternatives works, then this is the backup.

 

[marconi]

Do not be upset but I am taking a break from responding to any more posts. It sounds like you have a helpful and knowledgeable American engineer who can assist you.

Honestly, I cannot devote much more time to this interesting challenge. I have to turn my attention to another project to do with solar electricity for my brother-in-law.

When I have time I will/may return to my version of your challenging project.

I repeat we part for now but not for ever so to speak.

Good luck! Please do continue to post your progress because the thread you started now has a few thousand hits so many folk are reading it on the Electricians Forum.

?

 

[_q12x_]

Well, believe me or not (I get the feeling you don't, haha) , I do care about my project to make it as close as I imagine it in the first place. I agree, it is time consuming and hard, especially for me alone. Also slow. Well, not that alone, counting your 2 guys help. But still, I only have 2 hands and I have to keep focused on what is getting me closer to my final objective.
I agree with you. Breaks are good; and Im telling you a secret, breaks are also contributing to the good result as much as the hard work. I am personally take breaks, not so drastic, but more small and often, I kind of managing them. I also have a routine. That's why I'm slow. Also my inexperience in a lot of things, but that is another discussion.
I'll probably open another discussion on IR remote alone, since here is "too much" from what I get it... and I kind of agree, I kind of talked about everything on this way too long thread. We'll see.
I also thought remotes are easy. It looks they are not that easy. Very weird.
Thanks for the help so far. And have fun with that sport play on tv you said you are watching these days.
Cheers mate.

 

[marconi]

Good evening q12x. I am wondering how your project has progressed. I have been busy analysing a 20kW commercial solar electricity project. Have you thought about a career in renewable energy?

regards

marconi

 

[_q12x_]

"I am wondering how your project has progressed"
Oh, hello mister marconi !
I literally didn't check this website for awhile sorry for that, from 2 reasons, and I hope is understandable:
1-I was working slowly and nothing really to update with, and 2- I didn't made too much progress.
Me and my american friend- sorry to mention him but its how reality stands, yes, I get some help and im very grateful I have it to be brutally honest. And you are one of my friend since you got involved into this crazy project of mine.
So... the update so far, is that I am expecting some components to arrive from my friend from america, but in this time while I am waiting for them , I built with my friends help as well, a IR receiver and transmitter only on the breadboard so far. And we got splendid results, especially for the range from the IR to my palm in front of it and back to the receiver. Exactly as you did it, but with new circuit.
The real problem that remains is the interference from the window, that is directly in front of the wall, and in front of that panel and it's IR sensors. So..at any time, any wild IR light, from the sun or somewhere else, might switch this thing. And... hmmm... I am in a bit of depression.
The thing is, with these things, you always get the bad results from them, and if you're very smart or very lucky (or very persistent like I was and still am), you will get some good results as well.
Yes, it is hard as it gets. It's a challenge.
Have you thought about a career in renewable energy?
I wish to be able to work in such fantastic domains like electronics or electrics but I have no paper to certify the validity of my knowledge.... so it's a fantasy to even hope. I know my place very well and Im fine with it, for a long time. What are you thinking about? DO tell me, you made me curious.

 

[marconi]

Hello Mr Inventor. Good to hear from you again. The solar project has been decided on to go ahead but we need permission to connect it to the mains supply: this we have applied for. This means I have time to pick up where I left off with my version of your proximity switch.

l have an idea to control my ruler of lights based on whether the voltage from the sensor is increasing, decreasing or constant. This is to say that the actual voltage from the sensor is not important but rather whether it is going up, down or steady over two samples of it spaced out in time. It is being constructed at the moment. If you like a sensor of hand motion rather than hand proximity.

Are you in good form and making progress?

 

[_q12x_]

I'll probably have to draw the circuit - I didn't draw it yet and a movie to actually show you how things are standing at this point.
I will update soon.

 

[_q12x_]

 

[marconi]

Once again a nice clear video which shows your progress and current challenges. I liked that you have started to prototype circuits on the breadboard before moving them to the larger wings board. I'd like to see a ruler used to confirm your distances as I have done - we don't want any 'fisherman's tales'! ?

I will plough on with my project today and over the weekend.

Regards

Marconi

 

[marconi]

My breadboard so far.

 

[_q12x_]

"Once again a nice clear video which shows your progress and current challenges."
Thank you that you like it. And good job to you as well with the breadboard.

 

[marconi]

These are the stages I am working through with my version of your project:

1. Movement sensor to control the ruler of LEDs - my work at the moment, about 80% complete and then thorough testing;
2. Build pulsed LED array with 940nm torches* and associated pulsed LED receiver to produce Vs - pulsed sensor to distinguish torch reflections from steady (albeit slowly changing) ambient IR ;
3. Ambient IR monitor and controller to adjust for ambient IR - circuit built but yet to be fully tested and developed further as required.
4. Beep/click sound signal each time a ruler LED turns on/off.

* My current sensor arrays are 850nm.

 

[marconi]

My breadboard a day later.

 

[marconi]

This is a video demonstrating my version 2 of the ir proximity switch which includes the bleep/click sound as each ruler led turns on or off. As I have run out of space I will do version 3 the pulsed ir on a new breadboard. Quite a lot of time was spent on eliminating oscillation of an led if the hand stopped at a threshold or went through a threshold slowly.

 

[DPG]

This is a video demonstrating my version 2 of the ir proximity switch which includes the bleep/click sound as each ruler led turns on or off. As I have run out of space I will do version 3 the pulsed ir on a new breadboard. Quite a lot of time was spent on eliminating oscillation of an led if the hand stopped at a threshold or went through a threshold slowly.

Very nice Marconi

 

[marconi]

Very nice Marconi

I am a digital baby. So I aim to turn any problem into 1s And 0s as early as practical. Thereafter one has so many more options for signal processing. And it then becomes logical and mathematical which suits me. Analogue electronics is really an art which I have not had the opportunity or inclination to master. ?

 

[static zap]

I loved my 555 timer , but DIY ing it from op amps/comparators brings an understanding of Hysteresis and Long cycles for triangular waveform ... (I played with home brew car alarms !)

Analogue electronics is really an art which I have not had the opportunity or inclination to master.

 

[_q12x_]

Thank you for the video. You got good results. It's nice to hear the clicks.
It looks like it is finished. Can you make a circuit for me, with everything you have there? Thank you.
And this is my progress so far. Not that good.

 

[marconi]

q12 Good morning. If viewers were awarding marks you would receive high ones for the neatness of your construction whereas I most likely be told 'could do better'! I tend to be impatient and rush to see if something works and if it does I then leave it as is and move on to the next part. You are methodical and take the time to accurately record your circuits. I spent a good 2 hours trying to work out why my latest version did not toggle the lamp reliably. It turned out I had failed to connect the JK inputs to +5V ie logic 1 even though I had connected J and K together.

I am going to design next my 940nm pulsed sensor array and see how it performs. The major effort of version 3 is to maintain performance in spite of background IR from things inside the room and sunlight. I will keep you posted once I have something worthwhile to show. For this version I am using a better comparator LM311 which has the nice feature it can be 'strobed' ie told when in time to compare its inputs and produce an output - clearly necessary for a pulsed IR sensing system.

https://www.ti.com/lit/ds/symlink/lm311-n.pdf?ts=1617540813359&ref_url=https%3A%2F%2Fwww.google.com%2F

My versions 1 and 2 have used the LM339:

https://www.ti.com/lit/ds/symlink/l...rl=https%3A%2F%2Fwww.ti.com%2Fproduct%2FLM339

Happy Easter.

 

[_q12x_]

Happy Easter.
Thanks that you liked my "failure". Is kind of working as I said, but not that efficient (1 led always On), and only in night, when is out of day light. Also it is sensitive to my desk lamp as well, it is probably way too much amplified. But it works, in its limited way. It was more as an exercise with opamps for me, a practical one. The most used way of an opamp as I could seen it so far, is as a comparator. Then the other wonderful exceptions ways. At least is how I perceive it, now in the beginning. I must play more with it in the future.
Right now, I am planning on tweaking the amplification of the SCM - 2n7000, the one with the npn tr T3 and its led, somehow to make it work with the lm3914 pin 5. Currently, as a reminder, is only working directly from the Source of 2n7000 to pin5, because it is grounded by a 10k resistance R4.

My good american friend has sent me already an IR detector that has a chip in it, very advanced component and very miniaturized, and it will receive and convert automatically the signal from any remote control or signal generator. It is quite common but is a bit more expensive than a simple direct IR receiver like the black 3mm ones I have. The package is on the way, and we all wait for it's arrival.
Until then, I will tweak what else can be tweak.
Thats why I asked for your circuit, to see where and how did you linked the buzzer. I can not understand from your real picture, since its full of wires and little "black boxes".

 

[marconi]

The click is produced by comparing the number of LEDs illuminated at one instant - let us call it time t - with the number illuminated a short time T earlier in other words at t-T. My version 2 is using synchronous logic circuitry driven by a 'clock' running at several kHz which produces my clock ticks. It is bottom left with a single faint red LED next to it. I can number the ticks since the power up using the letter n, so a sample taken at the nth tick of the clock is Sn, and n is increasing from 1 to infinity.

As there are eight LEDs on my ruler, I sample at regular time intervals of T, to see which ones are on or off. This produces an eight bit sample word viz Sn= ( L1, L2, L3, L4, L5, L6, L7, L8). If an LED is lit Lx = logical 1 otherwise Lx = 0.

I then load Sn into an 8 bit register called P. Several clock periods later - T - the contents of P are loaded into another 8 bit register Q.

After another interval of T another sample, Sn+1, is taken of the LED ruler state, Sn+1 and loaded into the register P. The content of P is now Sn+1 - the latest sample - and the content of Q is Sn - the previous sample. After a further interval of T the content of P is loaded into Q. And this sequence repeats over and over again.

Registers P and Q therefore hold samples taken at Sn+1 and Sn respectively as n counts upwards. I could write this as Sn and Sn-1 which makes it clearer with is the latest sample Sn and which was the previous sample Sn-1.

An 8 bit logical comparator compares the contents of P and Q by doing the subtraction X = P - Q. If X = 0 then Sn = Sn-1 which means there has been no change of the state of illumination of the LEDs on the ruler over the interval T. If X does not equal 0 then more or less LEDs are illuminated now than there were before.

https://www.ti.com/lit/ds/symlink/sn54ls684.pdf?ts=1617648996931&ref_url=https%3A%2F%2Fwww.google.com%2F

The logical state of X then is a signal on whether the number of LEDs which are lit is steady (X = 0) or changed over successive time intervals T.

I use the X signal to gate a 1kHz square wave to the sounder to make the beep. Actually, because X is such a short duration pulse since T is actually very short in time I send X to a pulse stretcher (a monostable) to produce a longer gate pulse. This creates the click sound every time there is a single change of state - on to off or off to on - of the most significant LED.

 

[marconi]

q12 Some time ago you did not have in front of you a design of IR continuous wave active passive sensor which would gradually light your LEDs in response to the proximity of your hand. And now you do. To my mind then, describing your latest model of led wings as a ‘failure’ is unwarranted.

 

[marconi]

q12x Good morning. Just a thought on your latest IR sensor. The photodiode is operating in the photovoltaic mode which is ideal for low light levels because the dark current noise the photodiode produces is minimised. Any diode current flow is then mainly due to photons hitting the photodiode.

It may be that at the moment the single IR LED is not providing sufficiently intense illumination of your hand in front of the sensor which is compensated by using a high gain cascade of op amps (1) and (2) - (A = 100 x 10 = 1000). Of course this also means that ambient light from other sources will be detected and similarly amplified by a 1000.

What about brightening up the IR light you shine by having 2, 3 or 4 IR LEDs placed around the single IR photodiode? One might then reduce the gain of op amps (1) and (2) which would make your sensor less responsive to ambient light. The sensor would then mainly be reacting to the reflected light from the IR LEDs and tend to ignore ambient IR light. Worth a try? The second image shows my 850nm array of 4 ir LEDs and 4 pds.

 

[_q12x_]

Hello mister @marconi and thank you for your answers.
I kind of understand.... what you did there with the buzzer circuit, but PLEASE, make for me a simple circuit diagram. All I need is the output signal (pin1 to 10 of LM3914, or in other words the leds negative pins) and the input signal, (from what I understood, you used a comparator IC and a clock (quartz? or RC?)). But I still dont understand when the click sound is activated and by who. Explain in very simple words, not math words. Im an artist, I deal better with visual explanation than weird math algorithms explanations. Sorry but im not a math guy. Make me a short diagram please, draw it as simple and explicit as possible on paper and scan/photo it. Thank you ! I really appreciate your effort so far.
The other subject, the IR leds, YES, I will have to test more of them as you just did on your board. But again, this was more an educative circuit for me, since im quite new to both IR and opamps. Now im a bit more familiar with them. I will make it in the near future.

 

[marconi]

I hesitate to start designing circuits for you because I then become 'responsible' for them by working with you until they perform as desired when connected to your other modules. There is no point in copying the way I produced my 'buzzer' circuitry because my versions of your project are mainly using digital ics and techniques and as you can see from my video you do not have room. If you want me to guide you through the design process for something to work with your wings then that would be preferable to me. I spent quite some time making sure the LEDS on my ruler - so your wings LEDs - cleanly turned on or off without any fading or oscillation to ensure a single click each time there was a single LED change. As a fact your LM3914 fades the turning on and off of adjacent LEDs - it says so in the datasheet; I suspect - forgive I may be wrong - that you still have oscillations. Oscillations will be seen if you very slowly move your hand towards or away from the sensor or if you hold your hand in a position where adjacent LEDs turn on and off/off and on. Perhaps you could investigate.

In outline you would need to build a tone generator to drive the sounder. I suggest with a 555 chip. Is your sounder a piezo electric one and if so is it passive or active? If it an active one then it has an internal tone generator so you would not need to build a separate 555 tone generator. Mine is a passive one. Assuming a passive sounder driven by a 555 tone generator, we could use the trigger pin 4 to turn the tone on and off easily with a negative going pulse.

Next step would be to generate a negative pulse for each of the LED driver outputs of the LM3914 and then to combine them as logical OR (ie any driver output) to be used to turn the tone generator on briefly and thereby make the click sound. The sort of circuit I envisage for the negative pulse generator is a simple CR differentiator across each LM3914 LED driver transistor. Something like I have drawn in the attachment.

How does this sound to you?