Searching \ for 'AC to 3.5 V' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: techref.massmind.org/techref/power.htm?key=ac
Search entire site for: 'AC to 3.5 V'.

Truncated match.
PICList Thread
'AC to 3.5 V'
1999\02\10@150839 by Ralph Stickley

flavicon
face
Being a simple software guy, I was wondering how to get 3V for
a simple pic project from an A/C input - cheap!

Their used to be a Maxim part - MAX610 (or a MAX310) or something
like that (data book circa 1992 - Low cost A/C to DC converter).
You just plugged into the wall and got 5V out...I remember doing
that with some samples (and blew up a few of them too :-)
This part is no longer listed on Maxim datasheets.

Is there a one-chip solution for this anywhere ?

I bought some x-mas tree lights "Computer Controlled - 150 lights!"
...real cheap, $7.99 - when I tore it apart (while plugged in
of course :-), I found 4 Diodes, two resistors and an electrolitic
Cap.  The controller and maybe some other parts were on a board
with a big black glob of stuff on it...

I measured 3.1 volts across the cap (before I blew up my
volt meter...Of course when I hooked a scope to it, the board blew up
and now I have no more lights :-o(( something about isolation or
something) software is not nearly this much fun!

The Diodes are set up as a bridge, one resistor (1M) goes out to
the lights and the other resistor (820K?) goes to the cap where I
measured the 3.1 volts.

How did they get the A/C to DC from these parts ? Could they put
a zener (?) or some other magic part in the glob to get DC ?

Proving once again, a little knowledge is a dangerous thing...

Any circuit suggestions ? Thanks!!

Ralph

1999\02\10@165515 by Andres Tarzia

flavicon
face
Ralph,

Get the following document from the Microchip FTP site:
ftp://ftp.microchip.com/Download/Appnote/Category/PIC16/91008A.PDF

You will find there what you need (a $1 3V source from 115V AC).

Regards,
Andres Tarzia
Technology Consultant, SMART S.A.
e-mail: spam_OUTatarziaTakeThisOuTspamsmart.com.ar

{Original Message removed}

1999\02\10@170757 by Reginald Neale

flavicon
face
Ralph said:

>Being a simple software guy, I was wondering how to get 3V for
>a simple pic project from an A/C input - cheap!
>
>Their used to be a Maxim part - MAX610 (or a MAX310) or something
>like that (data book circa 1992 - Low cost A/C to DC converter).
>You just plugged into the wall and got 5V out...I remember doing
>that with some samples (and blew up a few of them too :-)
>This part is no longer listed on Maxim datasheets.
>

>Is there a one-chip solution for this anywhere ?

 Harris among others makes a nearly equivalent IC, the 1202/2402.
 Like the Maxim IC, it takes a few external parts, so calling it
 a "one-chip solution" is a bit of a stretch. Also, it does not
 provide any isolation. See below.

{Quote hidden}

 Best thing to do is power the tree lights with an isolation
 transformer rated for at least as many VA as the lights.
 Then your scope ground will still be a safety ground, and you
 won't blow the thing up just by connecting it.

 You're right -- it's tougher to blow things up with software.
 Can be done though, if you work at it hard enough :-)

>The Diodes are set up as a bridge, one resistor (1M) goes out to
>the lights and the other resistor (820K?) goes to the cap where I
>measured the 3.1 volts.
>
>How did they get the A/C to DC from these parts ? Could they put
>a zener (?) or some other magic part in the glob to get DC ?

 Part of the magic is that they get to use the string of lights as a
 dropping resistor.

 Reg Neale

1999\02\10@173713 by Sean Breheny

face picon face
At 03:03 PM 2/10/99 -0800, you wrote:
>I measured 3.1 volts across the cap (before I blew up my
>volt meter...Of course when I hooked a scope to it, the board blew up
>and now I have no more lights :-o(( something about isolation or
>something) software is not nearly this much fun!

Yeah, I think you'll find that we hardware people are all pyrotechnicians
at heart ;-)
After all, remember how long that thread was last year about blowing up
stuff (such as TO-3 power transistors, etc.)?

Sean

|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
.....shb7KILLspamspam@spam@cornell.edu  Phone(USA): (607) 253-0315 ICQ #: 3329174

1999\02\10@175208 by dave vanhorn

flavicon
face
At 05:36 PM 2/10/99 -0500, Sean Breheny wrote:
>At 03:03 PM 2/10/99 -0800, you wrote:
>>I measured 3.1 volts across the cap (before I blew up my
>>volt meter...Of course when I hooked a scope to it, the board blew up
>>and now I have no more lights :-o(( something about isolation or
>>something) software is not nearly this much fun!

You need an isolation transformer to test things like this.
Sounds like the AC hot lead was connected to circuit ground rather than the
neutral.
When you connect the scope ground, you pop the breaker (and maybe your
scope/probe)

1999\02\10@193141 by Graeme Smith

flavicon
face
GRAEME SMITH                         email: grysmithspamKILLspamfreenet.edmonton.ab.ca
YMCA Edmonton

Address has changed with little warning!
(I moved across the hall! :) )

Email will remain constant... at least for now.


On Wed, 10 Feb 1999, Ralph Stickley wrote:

> Being a simple software guy, I was wondering how to get 3V for
> a simple pic project from an A/C input - cheap!
>
> Their used to be a Maxim part - MAX610 (or a MAX310) or something
> like that (data book circa 1992 - Low cost A/C to DC converter).
> You just plugged into the wall and got 5V out...I remember doing
> that with some samples (and blew up a few of them too :-)
> This part is no longer listed on Maxim datasheets.

Why not buy a cheap D.C. adapter and use a regulator to drop it down,
one chip solutions tend to be a little too wierd for words.
>
> Is there a one-chip solution for this anywhere ?
>

if there is, it is probably a zero-crossing switching power supply
chip....


{Quote hidden}

The diode bridge gives you a full wave rectifier, that essentially turns
A.C. into ripply D.C., the CAP's smooth the waveform of the ripple,
reducing the ripples amplitude, and giving you essentially, a D.C.
Source, the reason that you got 3.1 volts across the cap, was that was
the amplitude of the ripple before the cap smoothes it out.

What you are probably wondering, is how to DROP the voltage from about
270V Dc, to a reasonable 3 volts....

Well part of the answer lies in the resistor... Ohms law states

E=I/R

(E being voltage, I being amperage, and R being resistance) so you
get a drop in voltage as you increase the resistance. The 1M resistor
thus drops the voltage to the lights.

The other resistor, is probably used to bleed off the caps, when you
drop the power. (Otherwise you might get a shock)

So, I question the use of the blob as a voltage reducer, it is
probably really, the controller, and the chip you thought was
the controller might be a voltage reference chip, or a driver for
the lights.

Usually the "Blobs" are the really "Sensitive" parts like a "PIC" that
hasn't been pre-packaged, and contains custom masking, or programming.

A zener, will create a voltage differential of its rating, because it has
a reverse bias voltage, that drops that voltage off the supply, so, given
the bridge, and caps, a zener in parrallel would give you a set voltage,
until it burnt to a crisp....

                               GREY
>
> Proving once again, a little knowledge is a dangerous thing...
>
> Any circuit suggestions ? Thanks!!
>
> Ralph
>

More... (looser matching)
- Last day of these posts
- In 1999 , 2000 only
- Today
- New search...