Searching \ for 'Is it right to supply 5Vdc.?' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=right+supply+5vdc
Search entire site for: 'Is it right to supply 5Vdc.?'.

Truncated match.
PICList Thread
'Is it right to supply 5Vdc.?'
1998\10\14@121816 by Eduardo Rivera

flavicon
face
Hi all guys,
Could someone give me his thoughts about this circuit?(hope is clear ASCII).
It is supposed to supply 5 volts and is powered directly from AC, 220 Volts
in this particular case. It looks for me that the zener is wrong biased.

Thanks. EDUARDO




0  <-------------- 220 Vac ---------------->      0
|                                                 |
|                                                 |
x----------|(-----\/\/\/\/----x-------|<|---------x Gnd
        220nF     1K 5W      |                   |
                             |                   |
                             |            100nF  |
                             x--|>Z----x---|(----x
                                       |         |
                        5 V  zener     |         |
                                       0         T Gnd
                                          5Vdc

1998\10\14@130930 by Peter Schultz

flavicon
face
Depend of how big Your family are or how good Your life insurance is.
Cheers,
PeterS

1998\10\14@140920 by Peter L. Peres

picon face
The zener is wrongly biased, swap the diode and the zener around. Also add
a 470K 0.5W resistor in parallel with the 220nF.

Peter

1998\10\14@213627 by Dwayne Reid

flavicon
face
The diode and zener are swapped - see below.  The 1K resistor is higher than
I would use - more like 220R 1 watt metal oxide.  The output filter cap is
WAY too small at 100 nF - I've marked it as 100 uF but might go larger.
Otherwise looks fine.
{Quote hidden}

dwayne


Dwayne Reid   <spam_OUTdwaynerTakeThisOuTspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(403) 489-3199 voice     (403) 487-6397 fax

1998\10\15@022132 by Dr. Imre Bartfai

flavicon
face
On Wed, 14 Oct 1998, Eduardo Rivera wrote:

>  Hi all guys,
>  Could someone give me his thoughts about this circuit?(hope is clear ASCII).
> It is supposed to supply 5 volts and is powered directly from AC, 220 Volts
> in this particular case. It looks for me that the zener is wrong biased.
>
> Thanks. EDUARDO

Hi,
Here is what I guess:

live                                              neutral
 0  <-------------- 220 Vac ---------------->      0
 |                                     D1          |
 |                                                 |
 x----------|(-----\/\/\/\/----x-------|<|---------x Gnd
          220nF     1K 5W      |                   |
                               -                   |
                               V  D2               |
                               _                   |
                               |                   |
                               x-------Z<|---------x
                               |            100nF  |
                               x---------x---|(----x
                                         |         |
                          5 V  zener     |         |
                                         0         T Gnd
                                            5Vdc

The maximum current can be sourced is about 10 mA. The diodes D1 & D2
should be capable to tolerate 500V or higher. The accidental swap of live
and neutral is fatal!!! The Dc output is to be buffered with appropriate
capacity (not shown).

Regards,
Imre

1998\10\15@032239 by Radoni Calin

flavicon
face
part 0 12426 bytes
<P><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;
C1&nbsp;&nbsp;&nbsp;&nbsp; R1</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp; ---||---/\
/\/\---</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp; |&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
|</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp; o&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
/ \ 1PM05</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
/ ~ \&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; R2</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>220V AC&nbsp;&nbsp;&nbsp;&nbs
p;&nbsp;&nbsp;
___ /-&nbsp;&nbsp; +\____/\/\/\______________________ 5V DC</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp; \&nbsp;&nbsp;&nbsp;&nbsp; /&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp; o&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;
---&nbsp;&nbsp;&nbsp; \ ~ /&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;
---&nbsp;&nbsp;&nbsp; ---+&nbsp;&nbsp; ---</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp; |&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
\ /&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;
/&nbsp;&nbsp;&nbsp;&nbsp; ---&nbsp;&nbsp;&nbsp; ---</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp; |&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 5V&nbsp;&nbsp;&nbsp;
/_\&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp; ----------
-------&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Zener&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
|</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&
nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&
nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;
---&nbsp;&nbsp;&nbsp; ---&nbsp;&nbsp;&nbsp; ---</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&
nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
1000uF&nbsp;&nbsp; 100nF</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&
nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
16V</FONT></FONT><FONT FACE="Courier New,Courier"><FONT SIZE=-1></FONT></FONT>

<P><FONT FACE="Courier New,Courier"><FONT SIZE=-1>C1 should be computed
like this :</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;220-Imax*R1-Ui&nbsp;&nb
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
1</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;--------------
= ----------</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;
Imax&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 2*PI*50*C1</FONT></FONT><FO
NT FACE="Courier New,Courier"><FONT SIZE=-1></FONT></FONT>

<P><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
- Imax is the maximum current you want from this schematics.</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
- I do not know the reason for using R1, but R1 is used in many schematics,</FON
T></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;
so put one there let's say 1K.</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
- The power of R1 must be bigger Imax*Imax*R1.</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
- Ui is a the voltage that can be measured between the + and - pins,</FONT></FON
T>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;
of 1PM05. You must choose Ui bigger the 5V.</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
- 1PM05 is (sorry I do not now the english name) made by 4 diodes,</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;
and support max.1A and max.50V .</FONT></FONT><FONT FACE="Courier New,Courier"><
FONT SIZE=-1></FONT></FONT>

<P><FONT FACE="Courier New,Courier"><FONT SIZE=-1>At the minimum consumpton
current (witch is zero), the Ui will be split on</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>R2 and the Zenner diode.
So, the R2 value will follow :</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Ui-5</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;
R2 = ----</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Ix</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
- for Ix you must use a value lower then the maximum current,</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;
supported by your Zener diode.</FONT></FONT><FONT FACE="Courier New,Courier"><FO
NT SIZE=-1></FONT></FONT>

<P><FONT FACE="Courier New,Courier"><FONT SIZE=-1>There is some observations
:</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
1. R2 will "eat" a piece of the Ui, let's call it Ur.</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;
If Ur is bigger the Ui-5 you will not get that 5V you want.</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;
2. What you do if the input, 220V AC, will vary. I don't now</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;
how is at your home, but I encountered somethime 210V AC,</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
;&nbsp;&nbsp;&nbsp;
and other time 230V AC !</FONT></FONT><FONT FACE="Courier New,Courier"><FONT SIZ
E=-1></FONT></FONT>

<P><FONT FACE="Courier New,Courier"><FONT SIZE=-1>If you want read this
advice :</FONT></FONT>
<BR><FONT FACE="Courier New,Courier"><FONT SIZE=-1>&nbsp;&nbsp;&nbsp;&nbsp;
Use a transformer and a IC! I can show you how, if you want.</FONT></FONT><FONT
FACE="Courier New,Courier"><FONT SIZE=-1></FONT></FONT>

<P><FONT FACE="Courier New,Courier"><FONT SIZE=-1>Calin.</FONT></FONT></HTML>

</x-html>

1998\10\15@090034 by paulb

flavicon
face
Dr. Imre Bartfai wrote:

> On Wed, 14 Oct 1998, Eduardo Rivera wrote:
>>  Could someone give me his thoughts about this circuit?  (hope is
>> clear ASCII).  It is supposed to supply 5 volts and is powered
>> directly from AC, 220 Volts in this particular case.

 I don't believe this!  We did all that last week did we not?  Wasn't
anyone reading?  Doesn't anyone remember?  Look at the archives.

 Reductionist approach as per Peter and Dwayne; the Zener shunts the
input, you only use one other rectifier (Zener should be 5V6).  The
output capacitor should be at least 100µF, preferably 1mF at 6V3.  I
believe the input series resistor should be 330 ohm ¸W as it functions
as a fuse in case of capacitor breakdown.  That was the focus of last
week's forum.

>  The maximum current can be sourced is about 10 mA.

 Correct for 220nF input capacitor.  Twice as much current can be
obtained using a bridge rectifier but you often require one of the PIC
supply rails to be either the active or neutral.

> The diodes D1 & D2 should be capable to tolerate 500V or higher.

 Garbage!  50V would be *eight times* over-rating.  Think, man!

> The accidental swap of live and neutral is fatal!!!

 Garbage!  *No* part of such a circuit must ever be either exposed to
possible or connected to ground.  *Every point* is to be considered
potentially live.

> The DC output is to be buffered with appropriate capacity (not shown).

 It might be nice to parallel the reservoir capacitor (electrolytic)
with one or more lower value, low ESI (Equivalent Series Impedance)
capacitors to suppress HF interference, but it is more likely that the
"100nF" was a typographical error where 100µF was intended ;-)

 Was it Eduardo who expressed surprise that a circuit obtained from the
Internet was wrong?  *Very Funny!*
--
 Cheers,
       Paul B.

1998\10\15@141624 by Eduardo Rivera

flavicon
face
Hello.

  The point here is not to return to the transformerless power supplies
(related previous topic). The statement requesting your opinion was clear
enough..."ask for your thoughts" about a particular supposed wrong cicuit.

Is it really *very funny* to express surprise if someone finds a wrong
application diagram downloaded from MICROCHIP's home page? What a sense of
humor.  What source are we learning from ?
It is  unequivocal acceptable to find some mistakes in one's homepage but
from a manufacturer? What about for example a  wrong data sheet,how could it
affect you?

-------------------

I don't believe this!  We did all that last week did we not?  Wasn't
anyone reading?  Doesn't anyone remember?  Look at the archives.

 Reductionist approach as per Peter and Dwayne; the Zener shunts the
input, you only use one other rectifier (Zener should be 5V6).  The
output capacitor should be at least 100µF, preferably 1mF at 6V3.  I
believe the input series resistor should be 330 ohm ¸W as it functions
as a fuse in case of capacitor breakdown.  That was the focus of last
week's forum.

>  The maximum current can be sourced is about 10 mA.

 Correct for 220nF input capacitor.  Twice as much current can be
obtained using a bridge rectifier but you often require one of the PIC
supply rails to be either the active or neutral.

> The diodes D1 & D2 should be capable to tolerate 500V or higher.

 Garbage!  50V would be *eight times* over-rating.  Think, man!

> The accidental swap of live and neutral is fatal!!!

 Garbage!  *No* part of such a circuit must ever be either exposed to
possible or connected to ground.  *Every point* is to be considered
potentially live.

> The DC output is to be buffered with appropriate capacity (not shown).

 It might be nice to parallel the reservoir capacitor (electrolytic)
with one or more lower value, low ESI (Equivalent Series Impedance)
capacitors to suppress HF interference, but it is more likely that the
"100nF" was a typographical error where 100µF was intended ;-)

 Was it Eduardo who expressed surprise that a circuit obtained from the
Internet was wrong?  *Very Funny!*
--
 Cheers,
       Paul B.

More... (looser matching)
- Last day of these posts
- In 1998 , 1999 only
- Today
- New search...