So what happens to the circuit if the leakage is too large?

Not sure yet!

 

This thread is about power-transfer, not signal.
The only other power-transfer isolation known to humankind is a transformer.

That was you unilateral assessment based in information you refuse to give to us. And no I will not take your word for it. You proved your lack of knowledge over and over.

Other isolated ways to transfer power:

Light
Microwaves
Radio waves
Mechanical
Hydrodynamic
Pneumatic

And I am sure others.

 

That was you unilateral assessment based in information you refuse to give to us. And no I will not take your word for it. You proved your lack of knowledge over and over.

well that's on me. I'm here for electronics info, not judgement. I'm not required to justify myself to you. If i blow up my house, not your problem.

Other isolated ways to transfer power:
Light
Microwaves
Radio waves
Mechanical
Hydrodynamic
Pneumatic
And I am sure others.

You're right! I should have said a trafo and cap are the only viable solutions to handle 3A without difficulty in a relatively small package, silent, low-cost, PCB-based power transfer. I added this to my question.

 

3A

So now you need 15W, not the 150mW in the title?

 

So now you need 15W, not the 150mW in the title?

Once we had 150 mW solution here, then out of curiosity, I ran the numbers for 3 amps (for a different application). I'd be happy to start a new thread for that, but one of the admins complained when I opened multiple threads on related topics, so it seems the admins prefer to keep related topics within a single thread.

 

What I see is that effectively half of the mains voltage will be capacitively coupled to the "isolated" circuit. Current limited , but how much current does it take to deliver an uncomfortable shock?? And even a small portion of half the mains voltage would be a lot of noise in an audio system.
Soif it is for a "system" that might be touched by people, or might handle signals or sound, the introduction of several volts of AC relative to "Neutral" may have an undesired effect.
So good luck with the top secret project.

 

effectively half of the mains voltage will be capacitively coupled to the "isolated" circuit. Current limited , but how much current does it take to deliver an uncomfortable shock?

It's isolated from the mains.
Below from post #27:

The AC bus is already isolated from mains by a UL certified commercial converter, so there's no shock hazard.

 

OK, so does that also mean that neither side is tied to earth ground??

 

OK, so does that also mean that neither side is tied to earth ground??

No.
One side can be.

 

OK, I went back and looked at post #1 again. the supply was ten volts at 100k hertz. Easy to filter to smooth DC after a rectifier. But still, while the shock hazard is not present, there is still the possible noise problem if there is the slightest leakage to the real world "ground" conductor.

 

there is still the possible noise problem if there is the slightest leakage to the real world "ground" conductor.

You keep making statements about circuit problems without stating the reason.
Don't see why a small leakage would necessarily translate into circuit noise for the circuit connect to the isolated circuit common (?).

 

there is still the possible noise problem if there is the slightest leakage to the real world "ground" conductor.

Do you mean power noise picked up by nearby audio circuitry?

 

I mean that both sides of the supply output are capacitance coupled to both sides of the AC input, with only two diode voltage drops in series. That should not be so very hard to visualize. So the demands on the ripple and noise filtering will be quite a bit.
So if the supply is not powering a circuit sensitive to a bit of noise there is no problem, it will not bother lights or motors or relays and such. And it will be OK for battery charging.
But to power an amplifier or a radio there would be a noise and ripple issue.

 

But to power an amplifier or a radio there would be a noise and ripple issue.

That's no different from the supply being directly connected to the AC input.

 

What is the reason for not wanting a transformer, aside from this instance where the power frequency is 100 KHz? Of course, transformers for that high a frequency are much smaller and lighter than those for 60 Hz operation. A transformer can easily provide hundreds of volts of isolation AND it can also have electrostatic isolation built in.

 

What is the reason for not wanting a transformer, aside from this instance where the power frequency is 100 KHz? Of course, transformers for that high a frequency are much smaller and lighter than those for 60 Hz operation. A transformer can easily provide hundreds of volts of isolation AND it can also have electrostatic isolation built in.

From what i've seen so far, it may be difficult to buy or make a 3A, 100 kHz center-tap trafo, even a planar, under 10mm tall, and heat may be an issue.

If my numbers above are correct, a suitable ceramic cap would be about 5mm on a side, and less than 5mm tall, at about half the price of the trafo or less. I haven't looked at cap efficiency/heat yet.

 

OK, suddenly the power required is a lot more. I was still thinking the 0.150 watts from post#1.

 

OK, suddenly the power required is a lot more. I was still thinking the 0.150 watts from post#1.

Once we had 150 mW solution here, then out of curiosity, I ran the numbers for 3 amps (for a different application). I'd be happy to start a new thread for that, but one of the admins complained when I opened multiple threads on related topics, so it seems the admins prefer to keep related topics within a single thread.

I assume that, at any power, caps will be smaller/cheaper than a trafo at the same power.

 

Once we had 150 mW solution here, then out of curiosity, I ran the numbers for 3 amps (for a different application). I'd be happy to start a new thread for that, but one of the admins complained when I opened multiple threads on related topics, so it seems the admins prefer to keep related topics within a single thread.

I assume that, at any power, caps will be smaller/cheaper than a trafo at the same power.

I would not make that assumption. As the frequency increases the amount of core required decreases.

 

• Supply: AC 100 kHz, 10V
• Output: DC 5V @ 30 mA, isolated, continuous
• Footprint: L 10mm x W 10mm x H 5mm
• Budget: $1 (preferably $0.50)
• Load:
  • ATTINY10, 200µA max, https://ww1.microchip.com/downloads/en/DeviceDoc/ATtiny4-5-9-10-Data-Sheet-DS40002060A.pdf
  • ACS711 Current sensor, 6mA, https://www.allegromicro.com/~/media/Files/Datasheets/ACS711-Datasheet.ashx

in a relatively small package, silent, low-cost, PCB-based.

What other details will help?

Could i use an SCR with a 555? This one is $0.13
https://www.digikey.com/short/nnzcdd3f

View attachment 331361
SCR Voltage Regulator Circuit
https://www.homemade-circuits.com/scr-voltage-regulator-circuit/

Moderator's note:
You created this, a new thread, to continue your discussion about the power supply. The new thread is here:
https://forum.allaboutcircuits.com/threads/isolated-150mw-ac-to-dc-regulator.202896/

The earlier thread is: https://forum.allaboutcircuits.com/...-low-power-supply-without-transformer.202878/ and it has been locked -you have made this confusing enough. Only one thread per topic please.