The transformerless supply question

rc3po said:

Yes sir, I have lots to learn - and loving every minute of it!
I don't see a problem troubleshooting the TLPSU. Plugged into my Isolation Transformer would give it isolation.

Click to expand...

tvtech said:

Hi

Any Transformer that is going to fit into an enclosure (see Avatar) that is :L=100mm, W=60mm,H=30mm will have to be SMPS in order for there to be any space left for the battery, electronics and so on. As a TV tech that deals with SMPS repairs every day of my working life......I wanted to stay away from any SMPS type circuitry.

I needed extreme electrical reliability with the circuitry having to handle periodic Mains surges of anything up to 300VAC + that kills SMPS's stone dead. (Think small generators on farms that have been known to "run away" and blow up everything until they can be switched off, or our notoriously bad electricity supply in rural areas and townships/squatter camps here that causes anything SMPS to eventually fail or blow up). I needed something that could handle this kind of electrical abuse without any drama.

So in 2009 I started investigating the X2 capacitor to see how it would handle the job as a Mains current limiter. I needed 120mA constant current at a regulated 10VDC which would take care of both charging the battery and powering the LED's.

One VERY important lesson I learned whilst using a cap in this way is NEVER LOOSE THE LOAD. If for some or other reason this happens you are going to have a lot of drama on your plate. The supply voltage from the cap will go sky high and destroy your project and possibly shock you too if you are poking your fingers around inside when it happens. (This happened in the development phase where I was using breadboard...and a wire going to the head (load) came loose. The Electrolytic smoothing cap exploded and the Regulator went to heaven etc). I never got physically shocked but I was still shocked at how quickly all blew up in front of me.

So, learning from this, I decided to put everything on a PCB. The only way I could accommodate everything safely was the board had to be double sided.

So, I designed the first double sided board always keeping in mind creepage distances etc. To cut a long story short, everything worked as expected with the first prototype boards. No nasty surprises.

But as any of you know that has designed or built anything from scratch.....fine tuning is very important.

So the board went through two revisions. Little things here and little things there. One of the parts built into the last revision is a 5W Zener that clamps the output from the Bridge and in so doing aids the series Regulator in staying a bit cooler when overload times come.

So, on the 9th and 10th of June last year 2013, with this little guy in it's ABS casing and 3mm Polycarbonate lens and a small hole drilled to accommodate the heat sensor onto the Regulator and sealed from prying fingers....it was put to the test.

I initially wanted to see if it could handle 400VAC for 30 seconds. I would of been happy with that. So the test began at 400VAC...

30 Seconds came and 30 Seconds went. No problem. I said to my friend "lets try 1 Minute and see what happens". No problem.
Lets try 2 Minutes. No problem.

Ended up a in a 5 Minute run at 400VAC. All good.

So being the kind of person I am and wanting to prove that all my hard work in this was worth the while I said " we are going to do another run @ 400VAC for 5 Minutes". Same result. No problems.

And then the final run @ 400VAC 5 Minutes later while this baby is still recovering. Same result. All OK. This is my personal unit that is exactly the same as the other testing units out there....and still to this day has shown no signs of the abuse I put it through last year in June.

So lets look at stuff here:

1. I agree that Transformerless power supplies can be dangerous to people that do not understand them.
2. I agree that they are bad news for people that are merely hobbyists playing around with a potential shock hazard.
3. I agree that they are bad news for people that won't listen. And then leave in a huff.

BUT:

They are excellent for certain applications ( like mine). Will I ever release a kit that people can put together on their own = NO
Will I ever show the details of my design on a Forum or the NET = NO.
Will I encourage Newbies to try this on their own = NO.
Will I release a a fully built, tested and sealed unit....already done. I have orders. And I am not hasty for money. People that have this little Guy for testing swear by it. They find uses I never dreamed of.

All I am saying is that Transformerless power supplies are out there. Many of them. And they are crazy over the top reliable if built the correct way.

And thanks to ETO and Mods and all to get this off my chest forever

See this link here: https://www.electro-tech-online.com...he-public-domain-at-last.136196/#post-1146578

Regards
tvtech

Click to expand...

tvtech said:

If you follow the whole X2 cap thing.....even with an Isolation Transformer you can still get shocked.

tvtech

Click to expand...

rc3po said:

Yes, but I won't be connected to mains ground...

Click to expand...

tvtech said:

Correct but you you can still get belted if the load is lost on the supply you are trying to fix...

Whilst I feel sorry for you....I am around 51 Years now...also feel totally battered.

Thing is a Forum is a place to discuss things and respect the powers that be. Do not disrespect Moderation or some of the amazing people that take on that very hard task. Maybe you have to learn still. I don't know.

I have given you more dislikes.....if you can deal with that then we can talk.

Sit back and reason

Think about stuff. I really don't dislike you nor does anyone here in spite of you pushing Moderation to the limit. Any other Forum out there would have probably thrown you away. Luckily ETO has Moderators that don't take things up personally.

Stay well,
tvtech

Click to expand...

MrAl said:

Hi,

Back on topic...

One of the first things they teach in electronics classes is how to measure voltage. They always say "keep one hand in your pocket" or something like that.

Click to expand...

Good advice that I always tried to follow. That and no ties around machinery, and no rings when working with high current.

When I was a kid I was into ham radio. My transmitter had a 3000 volt 500 ma power supply. One day the knuckle of my right hand got to close to the plate connection of the output tube. I know this because when my eyes opened I found myself in my comfortable chair with my finger and my right knee still smoking. Took forever to heal. Glad it wasn't both hands!

Click to expand...

JimB said:

TVtech

In the recently revised rules for the forum, we have the following statement on safety:

***************************************************************************************************************************************
Safety
Safety is important to everyone.
Ultimately you and you alone are responsible for your own safety regarding any circuit, device, or system you are working on.
Keep in mind that some members here may be as highly skilled and experienced as others are incompetent and careless.
That means that no one but you, the end user, can see and accordingly judge the potential dangers that others' advice or suggestions may hold for you, based on your present skill sets and knowledge of what you are attempting to do.
If you are not sure if something someone says is safe or legal, ask follow-up questions and do more research before attempting it. It is ultimately your responsibility to determine whether or not a solution is safe and legal. Use the information you get here at your own risk and to the best of your own judgment.
***************************************************************************************************************************************

In my opinion that covers the "liability issues".
As you comment, there is at least one popular electronics forum which forbids discussion of automotive topics and transformerless power supplies, that is their perogative to do so.
Is it helpfull? Probably not.

Click to expand...

Little Ghostman said:

I like old radio's and TV's, I dont have many (6 or 7), but I have tinkered with them all and restored to working, except one that is.
Some have the live antenna socket at the back, some of the radio's have live metal box's inside the wooden case. At first I thought this was mad and I am glad this isnt done anymore, then I started to meet people like said avionics tech above.
This got me thinking... Maybe today there is more stupid people around because we have lowered the chances for natural selection

Click to expand...

And yet the same forum is currently let a certain recently banned member from here, openly discuss what are clearly avionic circuits, and despite them being told and indeed concluding the same themselves, are turning a blind eye and trying to help the person fault find them!!!
Funny old world!

Click to expand...

And people still dont understand why I find it so hard to grasp certain rules and procedures! I am a logical thinker and simplistic person, I live in a complex and contradicting world. No wonder I struggle at times to fit in.

Click to expand...

JimB said:

LG wrote:

It is indeed a funny old world.
I doubt that the "recently banned member" is actually working on equipment which will be installed into an aircraft which will fly.
However, it could of course be that he is a completely competent guy who does work on such equipment in a safe and satisfactory manner, but who gets his jollies from winding up other competent guys with his charade of incompetence.

I considered it a possibility that he is actually a "charity case".
He works as a go-fer in a small workshop which actually does repair avionics equipment, and in his dowtime they let him play with scrap equipment in a corner of the workshop. As an extension of this playing he comes on to the internet forums asking questions which the workshop guys cannot be bothered to answer, or more likely he just cannot grasp.



Don't worry, it can only get worse as you go through life and gain experience.

A couple of examples from my career.

Many years ago, while working as an Instrument Technician I repaired a temperature controller for a furnace. A simple thing, a thermocouple drove a moving coil meter, a flag on the meter pointer intrupted a lightbeam and a photocell operated a relay to turn off the heater.
The faulty controller was in the workshop, I fixed it, and it was neededback on the furnace asap. So I took it to the furnace.
Now, I could do whatever I liked to that controller while it is in the workshop, but I could not connect it back up to the furnace, oh no, that is an electricians job.
So, along comes the electrician. He only has one hand! He is a mono-dexter!
So I, stand there, holding up the controller, while he deftly inserts the wires into the terminal block and tightens the screws, all done one handed.


Different time, different place, different company.
We had to set up a test rig to simulate a system that was mis-behaving.
Part of this test rig was a number of PCs running our own proprietary software.
At the time we were at best starved of resources (the PCs), so instead of buying a bunch of them (about 5) and making them available for general use in the office when the test was over, you could not imagine the solution which the management dreamed up...

... As it was the Houston (Texas) office who wanted the test done, they would supply the PCs.
As it happened, they had just upgraded their desktop PCs from 386s to 486s (yes it was that long ago), so they boxed up five of the old 386 PCs and sent them to the UK for us to use for the test.
It gets better...
So that we in the UK did not have to pay tax, VAT etc on these PCs, when the test was over, they were put back into the crate and sent back to the USA.

So whether some apparent half wit on some internet site is or is not trying to fix avionics, and what any random internet site considers should not be discussed, be it automotive electronics, avionics or nuclear reactor control systems, is just down in the noise floor of life.

Try not to worry about it.

JimB

An after thought.
Good persons who strive to help the "recently banned member" deserve a place in heaven. (good grief! did I just say that?).
For me, I have posted to help out that person, but never again.
I would not waste my time and effort on such a fools errand.

Click to expand...

I considered it a possibility that he is actually a "charity case".
He works as a go-fer in a small workshop which actually does repair avionics equipment, and in his dowtime they let him play with scrap equipment in a corner of the workshop. As an extension of this playing he comes on to the internet forums asking questions which the workshop guys cannot be bothered to answer, or more likely he just cannot grasp.

Click to expand...