Capacitive supply Vs economy

Go To Last Post
33 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Transformerless power supply design seems that is an economy and more compact solution compared with a transformer.But there is not primary/secondary current,what flows in the load or even in the zener for voltage regulation is the same current from the mains,there are no capacitance losses but the all circuit seem as a loss.In practice 40mA is the current,power consumption is 8.8 Watt with no load.
24 hours x 360 days x 8.8 Watt =76.032 KW x 0.61€=46.37 Euro per year.
Am i missing something.

Attachment(s): 

Last Edited: Thu. Feb 23, 2012 - 07:43 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

That does not provide any line isolation. It could be, and probably will be, lethal.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

And only economical if you only need a few milliamps. Capacitors rated at mains voltages are big and expensive.

Brand X has an appnote on these kinds of supplies.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Yes Jim,i know.This is a part of a dimmer circuit,i will put it in a well isolated plastic box and i do not recommend such a kind of design to a newcomer hobbyist.But it has a bit of "danger" in the wallet also.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
8.8 Watt with no load.Horror if i am not missing something.

The problem is you have multiplied rms current times rms voltage. Or other integral (mean perhaps?).
So the current through the cap (neglecting R-s and D-s) is C*U'=C*230*(sin(2*pi*50*t))'

And that gives C*230*2*pi*50*cos(2*pi*50*t)
3,3e-2A*cos(something*t)

From that current you can calculate the power the circuit draws, as this cap makes the voltage drop, not the power drop.

Mind your 1Mohm resistor must be rated for at least 400V (or two in series for 200V etc)
or perhaps it happened you already learned that. Bang.
Same applies to the cap. So if you try that test with a 250V cap, you will see a smoke and 230V RMS voltage accross that poor 47 ohm resistor. Bang.

It is perfectly economical if you do not pay for apparent power.

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

If the cap is an electrolyt you might see more than smoke. If you are close without eye protection you might end up seeing less or nothing...

As of January 15, 2018, Site fix-up work has begun! Now do your part and report any bugs or deficiencies here

No guarantees, but if we don't report problems they won't get much of  a chance to be fixed! Details/discussions at link given just above.

 

"Some questions have no answers."[C Baird] "There comes a point where the spoon-feeding has to stop and the independent thinking has to start." [C Lawson] "There are always ways to disagree, without being disagreeable."[E Weddington] "Words represent concepts. Use the wrong words, communicate the wrong concept." [J Morin] "Persistence only goes so far if you set yourself up for failure." [Kartman]

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The design works perfectly in practice,there is no any kind of problem in the design or in the using components,but i measured current with a digital amperometer and is 40mA AC.That is what makes me to freak because when started the design i thought that if a mini tranformer costs 2€ the 680nF/275v AC costs 0.7€ in retail price and the design is smaller with less pcb area and everything looks fine.

Last Edited: Thu. Feb 23, 2012 - 08:41 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

@geoelec: You should take into account the ballast capacitor acts as reactive load. Current through that .47mF cap has phase shift from mains voltage. See reference article for this circuit. Thus calculations shall have"power factor" (IIRC) included.
Design reasonable only on mains part of insulated, low power applications.
A good DMM with power measurement capability could be useful here.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
If the cap is an electrolyt you might see more than smoke.

I suspect he will see nothing more as it will trigger mains fuses almost instantly.

Quote:
But i measured current with a digital amperometer and is 40mA AC.

But it does not matter if it is digital or analog. Your current does not look like sinusoidal with that diode in series so either you need an RMS multimeter or you need to know how your DVM works to recalculate measurements. I am 99% sure this DVM has "Only for sinusoidal input" mentioned in it's datasheet.

Quote:
i thought that if a mini tranformer costs 2€ ..

How many of them do you need? One? One thousand? If less than 50 - get transformers. If more, let it be designed by someone experienced, before you hurt yourself.

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

And with oscilloscope the voltage measured across 47ohm resistor is about 5Vpp.And who said that in a lack of an experienced designer an electrolytic capacitor is used and thanks to the electric fuse of the house all the neighbourhood is not blown,so i must feel lucky because i didnt hurt my self?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Note that it is very hazardous to use an oscilloscope on non-isolated line applications. In addition to being hazardous, you will get currents from the line though the ground of the oscilloscope, leading, at the very least, to false indications. You could also have burnt wires.

If you MUST do so, then use an oscilloscope that can be totally isolated (battery power). If its a USB scope, then run it from a laptop with no charger connected. Then YOU should stand on a rubber mat and use only one hand to adjust things. And, make sure that your life insurance is paid up.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Thu. Feb 23, 2012 - 11:21 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

geoelec wrote:
... power consumption is 8.8 Watt with no load.
LinkSwitch-TN by Power Integrations; price it and see if it meets your price limit.
Two orders of magntitude less for no load power consumption.
Another way is to chop shortly after the zero crossing (or something like that):
FSAR001B by Fairchild Semiconductor (5VDC, 35mA max., 2mA max. operating current).
Inductorless Off-Line Regulator ICs by Supertex.
Wonder if a modified Roman Black regulator would work.
With LED lighting coming forward there are a lot of LED PWM controllers to do AC-to-DC constant current.
If need isolation can use the above into one of many efficient isolated DC-DC converters.

Isolated: easier to use a wall-wart unless you're concerned about losing it (misplaced/repurposed).
From experience, add some protection after the wall-wart to protect your circuit from a partially malfunctioning wall-wart (bad filtering) or lightning strikes.
If all-in-one then the transformer can be expensive; may be able to use an inexpensive 2:1 low power high frequency transformer. The question is how to do the feedback to the PWM controller.
A lot of AC-DC PWM controllers are available.

Ref. Power Integrations, Product Selector Guide, AC-DC Products.

"Dare to be naïve." - Buckminster Fuller

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

geoelec wrote:
0.61€
/KWH. I'm paying 0.23USD/KWH (0.17EU/KWH) (energy, taxes, fees, meter, contribution).
Another way Greece is getting raked over the coals.
geoelec wrote:
Am i missing something.
Supertex AN-H65, Synchronous CCSS Regulator (CCSS = Capacitor-Coupled Switched Shunt).

"Dare to be naïve." - Buckminster Fuller

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

0,61EUR/kWh?? Are you sure it is not 0,16EUR but 0,61EUR?

Quote:
I'm paying 0.23USD/KWH (0.17EU/KWH)

And I am paying 0,5PLN/kWh (0,12EUR/kWh) first tariff. (energy, taxes, fees, meter, contribution).

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

This is the Brand X appnote I wrote about.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

ka7ehk wrote:
Note that it is very hazardous to use an oscilloscope on non-isolated line applications. In addition to being hazardous, you will get currents from the line though the ground of the oscilloscope, leading, at the very least, to false indications. You could also have burnt wires.

If you MUST do so, then use an oscilloscope that can be totally isolated (battery power). If its a USB scope, then run it from a laptop with no charger connected. Then YOU should stand on a rubber mat and use only one hand to adjust things. And, make sure that your life insurance is paid up.

Jim

Jim would this work (safely)
http://www.youtube.com/watch?v=V...

/Bingo

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I been off for a couple days.It is useful to mentioned safety precautions and especially the oscilloscope usage in applications where the circuit is connected in mains without isolation.But microcontroller based electronics can be found everywhere,in irons,coffe machines,dimming applications,washer machines and the non isolated power supply tends to be a common practice.This is far from newbies,or hobbyists or school projects but every one in the repair field of consumer electronics works every day with such type of power supplies.
The price of KW/h is much less than 0.61€ but in fact not far away from reality since i made a couple of tiny13 dimmers and i intend to put some more in every room of my house,so five capacitive power supplied dimmer will be connected in the mains until they blown,from now to eternity maybe and the initial purpose was the economy and even the lamp prolonged life and in practice the economy result seems exactly the opposite,without them is better,due to the ancient power supply design.
Capacitor acts as a constant current source followed necessarily but a shunt regulator and thats the problem.The zener converts current to voltage,if the rest circuit consumes even not a mA current,zener cunsumes all the current to maintain the voltage regulation.So,every technique of current minimalization,the sleep modes,all the modern mcu's with pA of current ability consumption all are cancelled from the power supply design.So,i will use a modern power supply stage.
Many thanks to all of you.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
I been off for a couple days.

By "off" you mean OFF?
You are kidding?! You didn't try that trick with an electrolytic cap, did you? Don't you ever do that again! I was really worried about your absence!

Quote:
The price of KW/h is much less than 0.61€

that is?

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

No of course not,but as it seems capacitive and resistive divider based power supply comes from the stone age,something like as the resistors in the blackwhite televisions for the supply of the valves.
Can not talk about sleep modes into a such of thing.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I think you did not get the idea of how the capacitive power circuit really works. But I am not willing to explain it to you because I fear you will eventually try and build it some day and vanish from this forum for a little longer than "a couple of days".

Anyway:

Quote:

Quote:
Quote:
The price of KW/h is much less than 0.61€

that is?


that is?

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

But its worth to give a try to explain it and every one will become wiser.Well the green waveform is the current through R1 and blue is the current through the zener diode,phase shift is 90 degree and what?
The capacitor value instead 470nF is 680nF and with this capacitor the waveform is printed,load resistor is 10k.

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

(Off topic, but upon request)
To correct any wrong impressions, the price per kW/h is not *that* high and it's comparable to the prices mentioned by others. More specifically, for domestic users:

kW/h       Euro
0–800		0,05625
801–1000	0,07850
1001–2000	0,08150
>2000		0,09155

That's price for the electricity only. The taxes that come along in the electricity bill, well... that's another story.

-Pantelis

Professor of Applied Murphology, University of W.T.F.Justhappened.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

pnp wrote:
(Off topic, but upon request)
To correct any wrong impressions, the price per kW/h is not *that* high and it's comparable to the prices mentioned by others. More specifically, for domestic users:

kW/h       Euro
0–800		0,05625
801–1000	0,07850
1001–2000	0,08150
>2000		0,09155

That's price for the electricity only. The taxes that come along in the electricity bill, well... that's another story.

When you add all the special taxes, distribution costs ... and 13% VAT on top of those, the prices range from 0,1138€ to 0,1707€. A 9 to 12% price increase is planned for 2012. This means that residential users with less than 800 kWh (per 4 months) consumption will be billed 0,1241€/kWh, while those with more than 3000kWh will be billed 0,1914€/kWh.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

What is a [kW/h] unit? In our country we have the units of kW*h=kWh=3,6MJ for energy unit typically. Is kW/h a peak current unit or what?

Quote:
When you add all the special taxes,

I didn't notice that at first, but you have the rising price with increase of the volume sold!!

That is really extraordinary, as it contradicts the laws of classical economy. So according to this example:

kW/h       Euro
0–800      0,05625
801–1000   0,07850
1001–2000   0,08150
>2000      0,09155 

you need to install for example two power-meters in parallel to buy a 1600kWh share for 0,05625EUR?

I do not get it - why someone have planned it upside-down?

Quote:
and 13% VAT

We have it 23% for energy, I think. But I am not sure of rest of the services(transmission, billing etc.)

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Brutte wrote:
What is a [kW/h] unit? In our country we have the units of kW*h=kWh=3,6MJ for energy unit typically. Is kW/h a peak current unit or what?
You are correct, the unit is kW*h.
Brutte wrote:
I didn't notice that at first, but you have the rising price with increase of the volume sold!!

That is really extraordinary, as it contradicts the laws of classical economy.

Yeah, it contradicts, but it's true and it is kind of a "punishment" for highter consumption. Also a way to say: "But we offer you cheap electricity with 0,05" even though very few benefit from that. Most of the houses fall on the bigger scales. And one cannot just install a second meter, they are installed by the company only (which is also practically a monopoly).

-Pantelis

Professor of Applied Murphology, University of W.T.F.Justhappened.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
Yeah, it contradicts, but it's true

A small fridge is 250kWh, boiling ~1L(four teas) of water daily is 40kWh. Well, that 800kWh a year is more like a "survival kit".

EDIT:

Quote:
800kWh (per 4 months)

Now it is more reasonable. 360EUR/year gives 3,2MWh budget. That looks quite regular if you do not use AC or electric heating extensively (never been to Greece).

Quote:
and it is kind of a "punishment" for highter consumption.

Ok, now I get it. And you are not allowed to own several power-meters in one household.

Quote:
the prices range from 0,1138€ to 0,1707€.

That looks more like a regular price in EU. The other price with punishment is higher than here.

In Poland there is a tariff which is called G12 intended for domestic purposes(lower price of kWh wrt industrial) and its limit is 80MWh per year. So as you can see the limits are of different magnitude.

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

There is too much scholasticism in talking about the exact KW/h price and not about the efficiency of the circuit which obviously is too low!!The circuit is based in the losses to maintain the desired voltage regulation,and exactly is a straight loss of its own even without having to supply any kind of load.And every additional device of this type is connected consumes wasted current,something the i didnt noticed it before i make it in practice and is for the entire life of the product and the economy was the initial idea.Now,what i am thinking is to replace the power supply with a constant voltage type of supply even if it costs a little higher compared to capacitor.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
That is really extraordinary, as it contradicts the laws of classical economy.
..
I do not get it - why someone have planned it upside-down?

Most likely the government subsidize the electric energy price for people with low consumption. For example retired people or people with very low income. It contradicts the "laws of classical economy"? Depends how you look at it.
George.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
even if it costs a little higher compared to capacitor.

Mind transformer also faces the same problems. It has an idle active current - you can find that out by touching some idling transformer.

What I mean is that it is not the type of powering that is good or bad, but that it is the economy that dictates which is good and which is bad.

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

angelu wrote:
for people with low consumption. For example retired people or people with very low income.

Oh come on, that is unreasonable. Why do you see a direct relationship between an income of a household with an energy consumption? Perhaps some single is reach, middle-aged, has a fluorescent lighting and coal-powered heating(falls perfectly under 800EUR), while some elderly retired couple are not able to cope with coal heating and have no choice but to fall into the highest category? (I mean in Poland heating is a cost, I do not know Greece conditions but the lack of relationship holds).
Your explanation is demagogic. If it is supposed to solve some problem, then not the one you mentioned. Perhaps other.
And what if statistically the most frequent letter of a surname for people with lowest income starts with "S"? It is even simpler - you do not need a variable tariff pricing on each billing so you can save some paper for shorter bills.

kW*h       Euro
S-T      0,05625
A-H   0,07850
K-P   0,08150
other      0,09155 

?

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
Why do you see a direct relationship between an income of a household with an energy consumption?

Because the energy people uses must be paid; low income, less energy. They do not want to bother to check the people's income, but just look at the consumption.

Quote:
Perhaps some single is reach, middle-aged, has a fluorescent lighting and coal-powered heating(falls perfectly under 800EUR), while some elderly retired couple are not able to cope with coal heating and have no choice to fall into the highest category?

No, rich people lives in multi room / bedroom houses / vilas with 2 - 3 TVs, freezer, fridge, dish washer, washing machine, AC etc.
Not same for poor people with low income.
It seems to me you generalize based on exceptions.
Quote:
Your explanation is demagogic.

It is not my explanation, I just say how it is out there. Maybe not all countries has this energy price policy.
Usually the rich gets higher taxes, the electric energy is only one example.
George.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
It is not my explanation, I just say how it is out there. (...)

If I were rich I would invest in a modern (expensive) dishwasher and washing machine in such circumstances. Same with modern lighting, fridge, HVAC etc without the change of a lifestyle. I wonder how a "not that wealthy" household is going to cope with such investment. I think that the only thing that could change because of such energy politics is a level life of the poorest households actually - they will not be able to afford a cost of an upgrade and be forced to lower their level of life even further.
Quote:
Usually the rich gets higher taxes,

I am always willing to listen to the results of such experiments. As far as the experiments are not conducted on my skin.

"Tested on Greeks, no side effects"

No RSTDISBL, no fun!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Brutte wrote:
I am always willing to listen to the results of such experiments. As far as the experiments are not conducted on my skin.

"Tested on Greeks, no side effects"

And then released to the general population... :/

As a side-note, the greek electricity company, during the 80s IIRC, was actually advertising: "Buy more household machines, dishwashers, new fridges bla bla, electricity is SOOO SUPER CHEAP YEY!!!". :P So a couple of generations grew up not thinking about power consumption or energy savings at all. Fortunately, the change towards "green" technologies has started (even before the crisis knocks on our door) and I think/hope we are on the right track.

-Pantelis

Professor of Applied Murphology, University of W.T.F.Justhappened.