High AC voltage convert to DC voltage on driving IC

[Electronic Swear]

Currently I am designing a circuit for controlling motor.
And I need to convert a 230Vac to 12Vdc for supply low voltage IC. In
the past, because of low power consumption for IC, I just use some
resistors and transistor for this convertion.
________ ___ C E
230Vac o-----| |---|_R_|--+----+------\ /-----o 12V
output
| diode | | | ---
| bridge | --- | ___ B
| | --- +-|_R_|--+
o-----|________| | |
GND |
12v Zener
|
|
GND


Now, I have changed some components and it need more current to drive
it. And the past design is not enough to do so. Now, I want to know
any similiar simply circuit can convert 230Vac to 12V dc with arround
200mA current.

If I replace the transistor to the TO-220 7812, can it supply enough
output for me to use? Thanks~

 

[Winfield Hill]

Electronic Swear wrote...

Currently I am designing a circuit for controlling motor.
And I need to convert a 230Vac to 12Vdc for supply low voltage IC.
In the past, because of low power consumption for IC, I just use
some resistors and transistor for this convertion.
________ ___ C E
230Vac o---| |---|_R_|--+----+------\ /-----o 12V
| diode | | | --- output
| bridge | --- | ___ B
| | --- +-|_R_|--+
o---|________| | |
GND |
12v Zener
|
GND

Now, I have changed some components and it need more current to drive
it. And the past design is not enough to do so. Now, I want to know
any similiar simply circuit can convert 230Vac to 12V dc with arround
200mA current.

If I replace the transistor to the TO-220 7812, can it supply enough
output for me to use? Thanks~

Awwkk!! Awwkk!! Troll alert! Troll alert!!!!


--
Thanks,
- Win

 

[Tim Hubberstey]

Winfield Hill wrote:

Electronic Swear wrote...

[really bad idea snipped]

Awwkk!! Awwkk!! Troll alert! Troll alert!!!!

How can you tell? I can remember doing this kind of thing when I was too
young to know better so I know it could be real. I do _hate_ to waste
time on trolls, though.
--
Tim Hubberstey, P.Eng. . . . . . Hardware/Software Consulting Engineer
Marmot Engineering . . . . . . . VHDL, ASICs, FPGAs, embedded systems
Vancouver, BC, Canada . . . . . . . . . . . http://www.marmot-eng.com

 

[Rob Gaddi]

Hear hear. You specced 12V, 200mA. I'd overrate the wart to 300mA just
to give yourself some room to play. 12V DC, 3.6W adapter. If that
costs you $10 you overpaid for it. Doing your own off-line regulation
when you have pretty trivial power requirements doesn't start to pay
until you're cranking them out by the thousand.

Mook Johnson wrote:

I agree with the previous poster. It is very dangerous to use power from
the lines this way. You cold kill youself or so unsuspecting person that
happens across your device.

I would HIGHLY recommend using the Wall arts idea followed by a regultor or
puttin a dedicated transformer between the 230VAC and your curcuit. A fuse
would also be highly recommended so you don't burn the place down if things
go wrong.

 

[Rich Grise]

On Thu, 03 Feb 2005 23:24:25 -0800, Electronic Swear wrote:

Actually, I have changed to use 7812 on supply regulated voltage for
low voltage IC. The circuit is as following:

________ ___ ______
230Vac o-----| |---|_R_|--+-------+--| 7812 |-----o 12V
| diode | | + | --+--- | +
| bridge | --- | | ---
| | --- zener | ---
o-----|________|--+ | | | |
| GND GND GND GND
GND

Is it better to do so?

No. You are still going to kill yourself or worse, somebody else.

However, the R will be in very high WATT and what can I to do so?
Sorry, I am not familiar with such voltage convertion circuit.

Here's a place to start:

http://www.bestbuy.com/site/olspage.jsp?j=1&&CategoryID=cat08103&id=1051384550149&skuId=3857017&type=product&ref=21&loc=01

check out these links:
http://www.google.com/search?q=dc+wall+adapter

Good Luck!
Rich