Dropping 1V from a Regulated 6V Wall Wart

[John Fields]

Yeah, I was thinking something really low like that.

But these approaches have been to establish a new regulated voltage,
dependent on the value of the zener. There's nothing wrong with this,
but it would be simpler to just use a LDO 5V regulator as someone
suggested.

---
I agree.

Plus, you won't have the Zener tempco and delta VZ/delta IZ (small
though it might be since the change in IZ will only be caused by the
change in the transistor's Ib as the load current goes from 0mA to
200mA) to contend with. And, a BIG plus for the LDO, you won't be
dissipating the power the Zener will be _all the time_ , regardless of
the load current.

 

[John Fields]

Ok, I incorrectly guessed Beta (Chaos Master told me how to get
special characters and it doesn't work here) of 200 and set Iz at
40mA (a waste) to get the 500mW zener to operate at about half it's
rating. I know, I only needed 10mA if Ib really were 10mA.

---
Any common 5.6V 500mW Zener will have its Zener voltage specified at a
particular test current; 20mA. This current is what _must_ flow through
the Zener in order for the reverse voltage it drops to fall within the
bounds specified. 40mA will not only waste 20mA, it could cause the
Zener voltage to be out of spec. The beta of the transistor (more
properly the alpha) is almost unimportant in this case since the base
current will be very small compared to the collector/emitter current and
its change will have very little impact on the Zener current from
no-load to full-load.

 

[John Fields]

Ah! So, you mean R2 = 5*R1 or 5.R1 in K.A. notation.

 

[Active8]

Yes. It's been fun. I love this groups sense of humor.

JW (to his credit) just likes to play,
sometimes.

And I also like to play. See what I mean? I didn't spell out what I
meant or add an emoticon, and *my* meaning wasn't clear.

 

[Active8]

---
Any common 5.6V 500mW Zener will have its Zener voltage specified at a
particular test current; 20mA. This current is what _must_ flow through
the Zener in order for the reverse voltage it drops to fall within the
bounds specified.

I glanced at a generic curve. Not even sure where the Zener specs
(if any) *are* on this box.

40mA will not only waste 20mA, it could cause the
Zener voltage to be out of spec. The beta of the transistor (more
properly the alpha) is almost unimportant in this case since the base
current will be very small compared to the collector/emitter current and
its change will have very little impact on the Zener current from
no-load to full-load.

Yes, Beta's just for rule of thumb stuff. Base current is
negligible which is the idea of the pass trans, anyway. It allows a
practical resistor for such a small drop, whereas not using it
forces the resistor to handle most of the current and you know...

 

[John Woodgate]

I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth
link.net> wrote (in <[email protected]>
) about 'Dropping 1V from a Regulated 6V Wall Wart', on Tue, 30 Dec
2003:

Ok, I incorrectly guessed Beta (Chaos Master told me how to get
special characters and it doesn't work here)

Doesn't ALT0223 on the numeric keypad, with Num Lock on, work?
ßßß

 

[Active8]

I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth
link.net> wrote (in <[email protected]>
) about 'Dropping 1V from a Regulated 6V Wall Wart', on Tue, 30 Dec
2003:

Doesn't ALT0223 on the numeric keypad, with Num Lock on, work?
ßßß

ß
yeah. Chaos uses ctrl+alt+m for mu, etc. and that didn't work but
rang a bell.

I checked unicode and character map and it says the unicode number
is 03B0 or 944

? <== that's 03B0 or 944 obviously not ß (0223)
? <== that's 0994
¯ <== 223 a bar |
ß <== 0223 beta | these two foul me up. the leading zero matters.


ok 03b0 is for arial and 0223 is for courier. I didn't know unicode
encoded the font, just language or locale. i see it doesn't for the
standard ascii chars. odd, really.

It's all hex. no decimal charts on MSDN CD. ok another instance of
the sci calculator on the desktop where the reader sits won't hurt
or just paste from char map.

Thanks for the clue, John. Sorry if I'm still a bit clueless.

 

[John Woodgate]

I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth
link.net> wrote (in <[email protected]>
) about 'Dropping 1V from a Regulated 6V Wall Wart', on Tue, 30 Dec
2003:

ok 03b0 is for arial and 0223 is for courier.

No, this is "Windows 'extended ASCII' characters", not Unicode and 0223
works for any font that contains the character.

There are two different series; one of the form 'ALT1nn'and 'ALT2nn',
which are in no logical order and the other in the series ALT0128 (which
is €, the Euro symbol) to ALT0255 (which is ÿ). Not all of the
characters will show on the screen.

 

[John Fields]

Yes. It's been fun. I love this groups sense of humor.

And I also like to play. See what I mean? I didn't spell out what I
meant or add an emoticon, and *my* meaning wasn't clear.

 

[John Fields]

I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth
link.net> wrote (in <[email protected]>
) about 'Dropping 1V from a Regulated 6V Wall Wart', on Tue, 30 Dec
2003:

Doesn't ALT0223 on the numeric keypad, with Num Lock on, work?
ßßß

---
You ß believe it!

On mine, with NUMLOCK off, ALT 225 = ß, and ALT 223 = ¯

while ALT 0225 = á and ALT 0223 = ß


with NUMLOCK on, ALT 225 = ß and ALT 223 = ¯

while ALT 0225 = á and ALT 0223 = ß

 

[Jim Thompson]

---
You ß believe it!

On mine, with NUMLOCK off, ALT 225 = ß, and ALT 223 = ¯

while ALT 0225 = á and ALT 0223 = ß


with NUMLOCK on, ALT 225 = ß and ALT 223 = ¯

while ALT 0225 = á and ALT 0223 = ß

Wow! That's a BIG difference ;-)

...Jim Thompson

 

[Active8]

Of course not. See my email addy? It says invalid I don't try to
foul things up, that'd be masochistic.

 

[Bob Parker]

Isn't that too practical and simple?

Bob

 

[Active8]

I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth
link.net> wrote (in <[email protected]>
) about 'Dropping 1V from a Regulated 6V Wall Wart', on Tue, 30 Dec
2003:


No, this is "Windows 'extended ASCII' characters", not Unicode and 0223
works for any font that contains the character.

There are two different series; one of the form 'ALT1nn'and 'ALT2nn',
which are in no logical order and the other in the series ALT0128 (which
is €, the Euro symbol) to ALT0255 (which is ÿ). Not all of the
characters will show on the screen.

OK it does work in note tab lite regardless of font. What I meant
was that if I'm looking up the code in character map, it changes
for different fonts. It *does* say Unicode, also.

So I don't have an extended ascii chart. ok. Nothing on MSDN CD. As
usual, google rules when you know what to look for.

http://www.cdrummond.qc.ca/cegep/informat/Professeurs/Alain/files/a
scii.htm

says 225 is beta

so does this:

http://www.jimprice.com/ascii-128-255.gif

are we having fun yet?

ok 225 is beta in the alt2nn series and 223 is a bar. alt0223 is a
box.

That second link came from http://www.jimprice.com/jim-asc.htm

which has a lot of possibly useful links.

Thanks John,

 

[Active8]

On 30 Dec 2003 08:57:05 -0800, [email protected] said...

I did this a while back. Replaced the 7806 in the wall wart with a 7805.
Wade

Uh, yeah. I'm kicking myself in the ass. I'm the type who looks for
simple elegant solutions like moveing the table closer to the
handicapped person rather than try to move the heavy person to the
table and I didn't think of the obvious.

Ouch.

Nice to meet you , Wade!

 

[Ross Mac]

I did this a while back. Replaced the 7806 in the wall wart with a 7805.
Wade

Too easy Wade!....But still an interesting thread!

 

[Robert Monsen]

<html>&szlig</html>



ß is 223 decimal in the latin1 supplement...

http://www.unicode.org/charts/PDF/U0080.pdf

 

[John Woodgate]

I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth
link.net> wrote (in <[email protected]>
) about 'Dropping 1V from a Regulated 6V Wall Wart', on Tue, 30 Dec
2003:

So I don't have an extended ascii chart. ok. Nothing on MSDN CD. As
usual, google rules when you know what to look for.

http://www.cdrummond.qc.ca/cegep/informat/Professeurs/Alain/files/a
scii.htm

says 225 is beta

so does this:

http://www.jimprice.com/ascii-128-255.gif

are we having fun yet?

ok 225 is beta in the alt2nn series and 223 is a bar. alt0223 is a
box.

No. Both of your links give a DIFFERENT 'extended ASCII' series, not the
Windows one. There is no standard for 'extended ASCII', so there are
several different versions around.

I found the Windows list in an early WordPerfect manual. But you can
compile your own by just typing in the codes and noting the result.

 

[John Woodgate]

I read in sci.electronics.design that John Fields <jfields@austininstrum

You ß believe it!

On mine, with NUMLOCK off, ALT 225 = ß, and ALT 223 = ¯

while ALT 0225 = á and ALT 0223 = ß


with NUMLOCK on, ALT 225 = ß and ALT 223 = ¯

while ALT 0225 = á and ALT 0223 = ß

You need Num Lock on with some versions of Windows but with others it
can be on or off. ON always works, AFAIK.

 

[Watson A.Name - Watt Sun, Dark Remover]

I've tried to do this on numerous occasions. If you need any amount
of current at all, the big lump of stuff makes it too unweildy, even if you
do bite the bullet and put in a complex circuit that works.

Now, for regulated warts, I crack the case and shunt a resistor inside
the wall wart. You can add a switch if you have multiple applications.
If you need both voltages at once, it's still easier to use two
warts than to have this lump of regulator stuff hanging about.

I'm a little confused by your requirements. If you even considered a
diode, you can't be too concerned about the actual voltage...but you're
concerned about the .2V variability. Sounds like there's something
in there that's important but not disclosed???
mike

Well, I started out in this or another thread with a RF modulator that
requires 4.75 to 5.25VDC, probably because it would be off freq if the
supply V got out of tolerance. I talked about the weird connector,
someone said it's a Belling Lee connector, AKA Euro or PAL connector.
Now I now what it is, and I bot an adapter at Rat Shack for four
bucks. But I wanted something simple that I could solder onto the
pins of the RF modulator, I finally resolved the problem by using a 6V
unregulated wall wart, which is more like 7 or 8V, and a 5.1V zener,
and 39 ohm resistor as a shunt regulator. It works just fine. But I
still wanted a way to drop a single volt, with reasonable regulation,
better than a 1N4003 diode which varies by up to a quarter volt. With
a 1N4003 the voltage could be as high as 5.3 or 5.4V.


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