resistor used to convert 220V DC to 12V DC

[ruleworld]

i made a pwm inverter which takes a little portion of the generated
220V AC voltage as reference. the 220V AC is rectified with 1N4007
bridge and given to the ic using a 220K Ohm resistor. is it safe to use
a resistor this way to step down 220V DC? the ic operates at 12v dc.

 

[Phil Allison]

** Desperate Groper Alert

i made a pwm inverter which takes a little portion of the generated
220V AC voltage as reference. the 220V AC is rectified with 1N4007
bridge and given to the ic using a 220K Ohm resistor. is it safe to use
a resistor this way to step down 220V DC? the ic operates at 12v dc.

** Only safe as long as human contact is impossible with the inverter or
whatever it powers.

So no inputs or outputs.

Fully plastic encapsulated.



......... Phil

 

[ruleworld]

** Desperate Groper Alert



** Only safe as long as human contact is impossible with the inverter or
whatever it powers.

So no inputs or outputs.

Fully plastic encapsulated.



........ Phil

wtf r u talking about? did someone pee on your mother's face?

 

[Eeyore]

wtf r u talking about? did someone pee on your mother's face?

Why don't you just bugger off to where you came from ?

 

[ruleworld]

Why don't you just bugger off to where you came from ?

i do whatever i do. whats ur problem?

 

[Eeyore]

i do whatever i do. whats ur problem?

The problem appears to be entirely yours.

Incidentally, don't expect to be taken seriously when using kiddy
grammar and spelling. This is a group for design ppl not illiterate
kiddywinks with stupid half-assed enquiries that show an inability to
communicate effectively.

Graham

 

[ruleworld]

The problem appears to be entirely yours.

Incidentally, don't expect to be taken seriously when using kiddy
grammar and spelling. This is a group for design ppl not illiterate
kiddywinks with stupid half-assed enquiries that show an inability to
communicate effectively.

Graham

fine. just keep ur azz away.

 

[amdx]

i made a pwm inverter which takes a little portion of the generated
220V AC voltage as reference. the 220V AC is rectified with 1N4007
bridge and given to the ic using a 220K Ohm resistor. is it safe to use
a resistor this way to step down 220V DC? the ic operates at 12v dc.

For safety most ac line driven power supplies use a transformer to isolate
the circuit from the line voltage. If you have any problem with your circuit
it
could put 220V on the input, output or the case. It's not a good idea, get a
wall wart.
Mike

 

[Greg Neill]

fine. just keep ur azz away.

Show the world that that you've got a grownup's keyboard
and know how to use it. Cutesy contractions and
misspellings are for kiddiewinks text messaging on their
Playschool brand cell phones.

Now, back to your question. Can you explain more
clearly what it is you're trying to do, and what
the components are? It sounds as though you're
using a simple single series resistor to drop what
would be about 311 volts peak to an ic. What kind
of ic is it? Why don't you voltage divide before
rectifying?

 

[Greg Neill]

For safety most ac line driven power supplies use a transformer to isolate
the circuit from the line voltage. If you have any problem with your circuit
it
could put 220V on the input, output or the case. It's not a good idea, get a
wall wart.

He's built an inverter -- it generates the 220V from some
other supply (probably battery). It's not operating on
mains supply, it *is* the mains supply.

 

[ruleworld]

He's built an inverter -- it generates the 220V from some
other supply (probably battery). It's not operating on
mains supply, it *is* the mains supply.

yes that is true. the transformer output voltage is rectified using
1N4007 bridge. then given to optocoupler ic 4n35 using 220K ohm
resistor.. then the output of 4n35 is given to pwm controller ic sg3524.

 

[Michael A. Terrell]

wtf r u talking about? did someone pee on your mother's face?

Just ignore Phyllis. She's always on the rag, and she hates
everything in the universe, but her favorite thing to hate is anything
posted through Google.



--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

i do whatever i do. whats ur problem?

Eeyore is the troll behind door number 2.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[[email protected]]

i made a pwm inverter which takes a little portion of the generated
220V AC voltage as reference. the 220V AC is rectified with 1N4007
bridge and given to the ic using a 220K Ohm resistor. is it safe to use
a resistor this way to step down 220V DC? the ic operates at 12v dc.

You are in Bangladesh, correct? Greetings.

About that PWM inverter you made - is it a square wave generator? If
it's not, you might be making a bit more than 220 VDC after your bridge
rectifier. More like 220V x sqrt(2).

That said... from V=IR, the current from a 220k resistor looks like it
will be about 1 mA. Will your IC be happy with 1 mA?

From P=I^2 R, it looks like your resistor will become a 0.22W electric

heater. Can your resistor take 0.22 W? (Get a big one: rated at 1W,
say.)

Good luck...

Michael

 

[Michael A. Terrell]

He adopts the practice of Pissing in the Wind, its my
understanding the brits invented that act, and use it
on a regular basis.
Now i could be wrong, facts do have a way of getting
twisted over there in the UK ..

That's because some of the Brits are so damn twisted in the first
place. How else could they hate everything they see?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[[email protected]]

i made a pwm inverter which takes a little portion of the generated
220V AC voltage as reference. the 220V AC is rectified with 1N4007
bridge and given to the ic using a 220K Ohm resistor. is it safe to use
a resistor this way to step down 220V DC? the ic operates at 12v dc.

I have dropped voltage with a capacitor in series with the line
voltage. I only did it to drive the LED in an SSR but it should work
for an IC if you used the right regulation on the far end.
Certainly a transformer will work.

 

[Jamie]

ruleworld wrote:




Why don't you just bugger off to where you came from ?

He adopts the practice of Pissing in the Wind, its my
understanding the brits invented that act, and use it
on a regular basis.
Now i could be wrong, facts do have a way of getting
twisted over there in the UK ..

 

[Eeyore]

I have dropped voltage with a capacitor in series with the line
voltage. I only did it to drive the LED in an SSR but it should work
for an IC if you used the right regulation on the far end.

Don't forget some series resistance too or the switch on current might kill
things.

Graham

 

[Rich Grise]

yes that is true. the transformer output voltage is rectified using 1N4007
bridge. then given to optocoupler ic 4n35 using 220K ohm resistor.. then
the output of 4n35 is given to pwm controller ic sg3524.

If the circuit is:

220VDC ----- [R] ----- [opto] ---- GND

then be aware that you're only getting about 1 mA to the opto. If you want
to use that to regulate it, I'd do something to reduce the amount of
influence the opto characteristics have on the quality of the feedback.

How about just a voltage divider? 220K with, say 5K in series will give
you about 5V for about 220V in. Buffer that, and then drive your opto.

But, since it's already an inverter, why do you need the isolation in
the first place? Or is it a second level of isolation?

What is it you're trying to accomplish?

Cheers!
Rich

 

[[email protected]]

Don't forget some series resistance too or the switch on current might kill
things.

Graham

The SSR has about 1k in it. I put a diode in there too.
If I was going to drive a chip I would put the resistor in the feed
and zener off the excess voltage like an old Triumph motorcycle.