Need a circuit (220v to 12) low current.

A

ahonda55

Guest
Hi great forum :)
i need a circuit to convert the 220v AC to 12v DC , but without coils
(i have no experience in coils ;) )
i saw a circuit many months ago using a capacitor and some other parts
i can't remeber.
i need this circuit to run a very low current circuits like the NE555
circuit and about 5 mA relays etc. etc.

is that possible ??

ThanKs A lOt :)

regards


Ahmed
 
ahonda55 wrote:
Hi great forum :)
i need a circuit to convert the 220v AC to 12v DC , but without coils
(i have no experience in coils ;) )
i saw a circuit many months ago using a capacitor and some other parts
i can't remeber.
i need this circuit to run a very low current circuits like the NE555
circuit and about 5 mA relays etc. etc.

is that possible ??

ThanKs A lOt :)

regards
Click to expand...
Sorry to say, coils are almost certainly involved in a reasonable
solution to this problem. Many small electrical devices are powered
by small transformer based supplies that hang on the wall receptacle.
I don't know what country you live in, but I suspect that there is
some nearby source of such small supply that will provide something
close to what you need.

The unregulated ones are all based on something like:
http://www.electronics-tutorials.com/basics/power-supply.htm

But some include a linear 3 terminal regulator:
http://www.hometech.com/power/powersup.html#XA-781RG

These little wall mounted transformer supplies have been made in such
numbers that I would be surprised in there are many around you for
salvage or purchase.
 
Thanx a lot , i live in Egypt , and there is a lot of wall-mount
transformers here, but i was looking for make a simple circuit like
the one i had seen.

i will search for that page and when i find it i will post it here.

Thanx a lot.
 
"i need a circuit to convert the 220v AC to 12v DC , but without coils
(i have no experience in coils ;)   )
i saw a circuit many months ago using a capacitor and some other parts i
can't remeber.
i need this circuit to run a very low current circuits like the NE555
circuit and about 5 mA relays etc. etc.
is that possible?"
____________________________________
Re;
Yes it is possible to use the capacitor as a zero power voltage dropping
device. A 0.2uF cap in series with a .5A fuse and two back to back 1W,
18V zeners will provide an 18.7V (or so) clipped AC waveform across the
zeners. This can be fed into a full wave bridge and then flitered by a
capacitor of 470uF or so and then you could use a 7812 (or other fixed)
three terminal regulator to get the requisite 12V.
Just keep in mind that the circuitry will not be isolated from the main
potential and will present a shock hazard.

-Dan Akers
 
Hi all , i had searched for the page and here it is ...

http://www.aaroncake.net/circuits/supply5.htm

check it and tell me will it work as shown ? and what about the 220v
AC input.

Thanks in advance :)
 
ahonda55 wrote:
Hi all , i had searched for the page and here it is ...

http://www.aaroncake.net/circuits/supply5.htm

check it and tell me will it work as shown ? and what about the 220v
AC input.

Thanks in advance :)
Click to expand...
You said you want a simple circuit. Please follow
John's advice - use a wall transformer. It *IS*
simple - simpler than wiring up a capacitor and a line cord.

If you want to build the DC supply, use a wall transformer
that lowers the voltage from 220 to ~12 volts AC, a capacitor,
bridge rectifier and a 3 terminal voltage regulator chip. That
will be MUCH safer for you, and will do what you want. The
circuit on the link you posted will not drive a relay.


LM7812
---------
+-----------+--- |in out|--- Vout +12
| | | Gnd |
--------- ------ [C1] ---------
| Wall | | + | | |
---| Trans- |-------|~ BR ~|---+ +----------+-------- Gnd
---| former |---+ | - | | |
|220 12| | ------ | |
-------- | | | |
| Gnd | Gnd
| |
+--------------+


BR = bridge rectifier
C1 = 2200 Uf 25 V
Use a LM7812 3 terminal voltage regulator in a TO220 package

Ed
 
Ok friends , i will get you advice .

Thank you very much .
 
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