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HELP: Un-isolated Power supply problem

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All of the flapping in this thread came from this phrase in post #1: "a capacitive un-isolated standard circuit..." There is no such thing. Six different people have responded, and we envisioned six different circuits based on you description, and all of us *guessed* wrong. Mine had 3 parts, while the schematic you later posted has 14. That kind of disconnect guarantees failure.

You said you provide schematics whenever necessary. This is a question-answer help forum, and your question involves unintended circuit interactions. How is that not the definition of "necessary"?

I brought up your 9-year membership not as some kind of shot at immaturity; just the opposite. I was saying you have more than enough exposure and experience to know what is needed to bring someone up to speed on your situation.

All (other people's) sarcasm aside, there is a legitimate question there. Since you know that the two sides of an AC power line connection are drastically different, why is it possible for the circuit to be connected incorrectly. Polarized AC plugs have been around for over 1/2 century, so the idea that something has a connection requirement that is critical to its operation hardly is new. Is making the circuit universal a real requirement, or can the problem be solved with a less ambiguous power connection?

ak
 
I still don't understand why the power and common lines are being reversed?
It should not happen, but it does happen. (fools and wires)
It should be easy. Connect black to black and white to white (red to red) But some people just can't do it.
 
No reply in 0ver 24 hours so does that mean he figured out (through no act of rationalization and logical process of course) that it only works properly when its wired properly? o_O
 
Hi tcmtech

I tried to find a rationalised and logical process by asking here, but as stated earlier, no one is helping with an explanation other than few helpful guys like ronsimpson , Les Jones

And yes , it will work only when wired correctly!
I will have to live with that
 
abicash,
Everyone that replied was trying to be helpful. As we all try to give accurate answers we need accurate information to base the answers on not just guesswork. We have seen people with all sorts of odd variations of circuits such as expecting a DC component to frow through a capacitor. This was on a cappacitor dropper type power supply using half wave rectification with a single diode. Hopefully next time you ask for help you will be prepared to give more information.

Les.
 
And yes , it will work only when wired correctly!
I will have to live with that

And why would you want it wired incorrectly when you know that it will only work when wired correctly?

To most of us what you are asking is sort of like this, I have a light switch that when wired correctly in the live line turns my light on and off as it should be but when I put it in the earth ground line it doesn't turn my light on and off and I have no rational reasoning why it only works when I wire it where its supposed to be.

The thing is the device you have is clearly polarity/line/load direction sensitive so what exactly is so hard to understand about that?
To us its like saying you have a battery charger that only charges batteries when the positive of the charger and the positive of the battery are connected together and you cant figure out why it doesnt work right when you hook the leads up backwards.

That's why you are being given a hard time.
 
Hi tcmtech

You are doing it again.:arghh:

Why is it so hard to understand?
Isn't all engineering design about designing for the inevitable?
As ron had stated earlier
"It should not happen, but it does happen. (fools and wires)"
Aren't there battery reverse protection circuits? Although RED is positive don't people wire it to negative, explaining the need for such a circuit?

I know that it has to be wired correctly.I am the designer.
I am taking care of the occasional fool who will not!

If you are not able to contribute to an explanation or a solution to the exact problem why do you participate in the group beating ? maybe it explains your signature!

I have provided complete schematics in my latest post above.
Please take a look and point to the problem if you can.
 
Thanks for the schematics.
Comments (just for fun)
D1-D4 do not need to be 1N4007 high voltage type. They could be 1n4001 through 1n4007. Probably could use lower current diode.
I think R3 has no function. What value? Depending on R3 the voltage on D1-D4 will be limited by ZD1.

R2 has many volts across it. What size of resistor? Will it take the power line voltage? Maybe upsize the resistor or use two.

When I built these I was trying hard to make C1 smaller. (cost and size) This limits the current so I wanted to keep the current use down. Example LD1 is a big load. Also LD2 and the Relay pull current. There are ways to light LD1 with out pulling current. (sounds funny)

I probably have this supply in SPICE if you want to see how it functions under 50/60hz, 110/220, high line, low line.
 
I know that it has to be wired correctly.I am the designer.
I am taking care of the occasional fool who will not!


If the fool can't get two wires put together correctly they shouldn't be working on a AC powered system..

Also a little note on the installation instructions to point out that the device needs to be wired in a specific way to work properly and should it not work to try reversing the leads is necessary would help alleviate some of the problems associated with general incompetence and stupidity.

As a designer you should know better than to try and design around stupidity. Stupidity will always a way to overcome your design. :(

Believe me I have tried to design for stupidity and it always won. Years ago I designed a fully automatic boiler control system for a buddy of mine. It was so simple that the only two instructions to work it were,

1: Start a fire.
2: Push the run button.

He still managed to eff that up multiple times and figured I should make it simpler. :banghead:
 
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