Maker Pro
Maker Pro

Dropping 1V from a Regulated 6V Wall Wart

  • Thread starter Watson A.Name - Watt Sun, Dark Remover
  • Start date
J

John Woodgate

Jan 1, 1970
0
I read in alt.binaries.schematics.electronic that Watson A. Name - Watt
[email protected]>) about 'Dropping 1V from a Regulated 6V
Wall Wart', on Wed, 31 Dec 2003:
I talked about the weird connector,
someone said it's a Belling Lee connector,

That's a coaxial connector, a bit like a phono plug but with a smaller
centre pin. Is that what you have?
AKA Euro or PAL connector.

I'd forget those descriptions if I were you. Certainly the Belling
connector has very little indeed to do with PAL. It is the subject of an
IEC standard - IEC 60169-2.
 
W

Winfield Hill

Jan 1, 1970
0
I needed to drop 1V from a 6VDC 200 mA regulated wall wart, so
I tried a 3 amp rectifier, but it varied by more than .2V over
a range of loads. So I tried this: (view with courier font)

+ From wall [edited for brevity]
wart >--+---+-----+
| |
| |
400 \ / 2SC2334 or TIP31
ohm / |/ NPN power TO-220
WW \<-----| Heatsink optional
pot / |\
| E\
| |
| |
+----+----+----> + output
to load
- >-----------------> -

Hmm, a complementary-darlington emitter-follower transistor would
be less sensitive to changes in load current:

: +6.0V, from wall wart
: >--+--------+------+
: | | |
: | 220 | Q1 2sa1011
: | | |/E pnp TIP32
: | +----| etc
: | | |\
: 1.0k |/ |
: pot <---| Q2 |
: | |\E npn |
: | | |
: 7.5k +------+-----> + output
: | to load
: - >--+---------------------> -

Here the Q2 voltage drop is much more predictable, because it has a
relatively steady current set by Q1's base-emitter resistor, which
has about 0.55 to 0.75V across it despite output load changes. The
Q2 current is about 3 - 5mA and we expect a Vbe drop of about 700mV.
The lower end of the pot sits at about 5.3 volts.

The most serious problem with this circuit is its complete reliance
You almost had it- put the Vbe multiplier inside the feedback
loop and buffer like so:

6V >---+------+-------+ [edited for brevity]
| | |
| 22 c
| | |/ Q1
| +-----| TIP31
| | |\
== | e---+----+----> 5V
| c Q2 | |
| \| / |
| |-------> \ |
| /| / ===
| e | 1000U
| | | |
GND >--+------+-----------+----+----> GND


Watson A.Name - Watt Sun, Dark Remover asked:
I'll toss one together, but what value should I use for the Pot?
10k? Lower?

This looks a lot like the current limiter circuit, 'cept for the pot.

No, it's an ordinary regulator, using Q2's Vbe (roughly 0.7V) as a
voltage reference. The pot as shown would be a poor choice because
valid adjustments would only use a small part of the pot's range.
No doubt nospam knew that and was just simplifying his drawing by
using one part instead of three. This should work; the top of the
pot has about 0.82V when the regulator is calibrated for 5V out:

This circuit has several problems. The tempco of Vbe is bad, but
the uncertain current through Q2 an even worse problem. This is
because the voltage difference between the +6V input and Q1's base
is small (and may vary widely), and Q1's base current is unknown.
If Q2's current changes by a factor of 10, its Vbe will change by
about 60mV, or nearly 10% of its value. As a result Q2 makes a
poor voltage reference in this circuit, even if manually adjusted.
I'm wondering if it's such a good idea to have such a large cap on
the output. When the wall wart is powered off, all that current
tries to go backwards thru the pass transistor.

A big cap is fine, maybe even necessary in that location, because a
small output cap could make the feedback loop unstable. We discuss
this issue in AoE and call it brute-force compensation.

The current won't go backwards for several reasons. The wall wort
probably doesn't draw output terminal current when the AC is off.
If it wanted to, Q1's Veb breakdown would certainly be above 5V so
no current would flow anyway.

Jim Thompson wrote...
Try this...

+ From wall [edited for brevity]
wart >--+---+-----+
| |
20 Q1 |
| / 2SC2334 or TIP31
| |/ NPN power TO-220
o------| Heatsink optional
| |\
| E\
| |
| o-----> + output
| | to load
__|___/ 2.2k
/ /\ |
/ \-------o
/ \ |
-------- 2.7k
| TL430 |
| |
- >------o---------o------> -

You may need a compensation cap between cathode and control pin.

This is a much better approach, using TL430's 2.75V reference with
a built-in error amplifier. The more popular TL431 can be used with
its 2.50V ref if the feedback-sensing resistors are the same value.

But I'm not happy with the output emitter follower in the circuits
above, because the low Vin - Vout difference leads to such widely-
varying currents through the control element. Perhaps my circuit
can be combined with Jim's circuit:

: +6.0V, from wall wart
: >--+------+------+
: | | |
: | 220 | Q1 2sa1011
: | | |/E pnp TIP32
: 750 +----| etc
: | | |\
: | |/ |
: +----| Q2 |
: | |\E npn |
: | | |
: | +---+--+----> + output
| | to load
__|___/ 2.7k
/ /\ |
/ \--------o
/ \ |
-------- 2.7k
| TL431 |
| |
- >----o----------o-------> -

Thanks,
- Win

whill_at_picovolt-dot-com
 
W

Winfield Hill

Jan 1, 1970
0
Winfield Hill wrote...
Perhaps my circuit can be combined with Jim's circuit:

: +6.0V, from wall wart
: >--+------+------+
: | | |
: | 220 | Q1 2sa1011
: | | |/E pnp TIP32
: 750 +----| etc
: | | |\
: | |/ |
: +----| Q2 |
: | |\E npn |
: | | |
: | +---+--+----> + output

I'm still not happy with the poor dropout-voltage capability of
this circuit. It should be able to operate with Vin much closer
to Vout. Aha! Simply adding a diode and resistor lets us reduce
the dropout voltage down to near the saturation voltage of Q1.

: +5.3 to 9V
: >--+-----+------, SIMPLE 5.0V REGULATOR
: | | |
: | 220 | Q1 2sa1011
: | | |/E pnp TIP32
: 470 o----| etc
: | | |\
: | |/ |
: o---| Q2 '----o----> +5.0V
: | |\E npn | output
: | | | to load
: | | 1n4148 |
: | '--o--|<|---o
| | |
__|___/ 1k 2.7k
/ /\ | |
/ \----- | -------o
/ \ | |
-------- | 2.7k
| TL431 | |
| | |
- >----o--------o--------o----> -

Of course, an even more simple circuit is possible, using one
of the many low-cost low-dropout three-terminal regulator ICs.

: +5.3 to 9V etc
: >-------, EVEN MORE SIMPLE 5.0V REGULATOR
: __|__
: | |
: | |---+---> +5.0V
: |_____| _|_ output
: | --- to load
: | |
: - >-------o------o---> -

But this circuit isn't as much fun. :>)

Thanks,
- Win

whill_at_picovolt-dot-com
 
W

Watson A.Name - Watt Sun, Dark Remover

Jan 1, 1970
0
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

This alt 0233 --> é looks to me like it's an accented e, as in Jose'
What's it look like to you?

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
A

Active8

Jan 1, 1970
0
On Wed, 31 Dec 2003 14:29:34 -0800, Watson A.Name - "Watt Sun, Dark
Remover said:
This alt 0233 --> é looks to me like it's an accented e, as in Jose'
What's it look like to you?
An e with a single dot over it, not the accent mark as in Jose'. I
think it's one of those pronunciation symbols.
 
A

Active8

Jan 1, 1970
0
I read in alt.binaries.schematics.electronic that Watson A. Name - Watt
[email protected]>) about 'Dropping 1V from a Regulated 6V
Wall Wart', on Wed, 31 Dec 2003:


That's a coaxial connector, a bit like a phono plug but with a smaller
centre pin. Is that what you have?


I'd forget those descriptions if I were you. Certainly the Belling
connector has very little indeed to do with PAL. It is the subject of an
IEC standard - IEC 60169-2.
It looks (the outer part) exactly like one of those RS push on F
connectors - the male one (male center conductor, female housing)
but the center conductor is hollow and split as if the mating
connector would compress it and cause it to seize the mating
connector's center conductor which in that case would make the CIQ
(connector in question) female and female no thread. I couldn't
quite get a real idea of the size from the photo. Let's check
Pasternack.

The PAL connector in this book is a push on, but the CIQ can't be
this PAL connector. The one I'm looking at is male-female into
female-male with the male housing (which would correspond to the
CIQ) is .370" OD.

I see 75 ohm MCX connectors where the jack corresponding to the CIQ
accepts a plug with a .147" OD housing - seisure and all.

I'd replace the friggin' thing with something I can lay hands on
easily. F connectors are common enough. Push ons I only use for
testing.
 
A

Active8

Jan 1, 1970
0
On 31 Dec 2003 14:00:52 -0800, [email protected] said...
Winfield Hill wrote...

I'm still not happy with the poor dropout-voltage capability of
this circuit. It should be able to operate with Vin much closer
to Vout. Aha! Simply adding a diode and resistor lets us reduce
the dropout voltage down to near the saturation voltage of Q1.

: +5.3 to 9V
: >--+-----+------, SIMPLE 5.0V REGULATOR
: | | |
: | 220 | Q1 2sa1011
: | | |/E pnp TIP32
: 470 o----| etc
: | | |\
: | |/ |
: o---| Q2 '----o----> +5.0V
: | |\E npn | output
: | | | to load
: | | 1n4148 |
: | '--o--|<|---o

Now, did you do this years ago and just walk through the thought
process for the benefit of the group, kinda like the "Now Read This
Article and Burn it." article, pulling a rabbit out of your hat to
the awe of the crowd? :) or what?

Happy New Year and best of health.

Mike
 
F

Fred Bloggs

Jan 1, 1970
0
Winfield said:
Winfield Hill wrote...


I'm still not happy with the poor dropout-voltage capability of
this circuit. It should be able to operate with Vin much closer
to Vout. Aha! Simply adding a diode and resistor lets us reduce
the dropout voltage down to near the saturation voltage of Q1.

: +5.3 to 9V
: >--+-----+------, SIMPLE 5.0V REGULATOR
: | | |
: | 220 | Q1 2sa1011
: | | |/E pnp TIP32
: 470 o----| etc
: | | |\
: | |/ |
: o---| Q2 '----o----> +5.0V
: | |\E npn | output
: | | | to load
: | | 1n4148 |
: | '--o--|<|---o



Of course, an even more simple circuit is possible, using one
of the many low-cost low-dropout three-terminal regulator ICs.

: +5.3 to 9V etc
: >-------, EVEN MORE SIMPLE 5.0V REGULATOR
: __|__
: | |
: | |---+---> +5.0V
: |_____| _|_ output
: | --- to load
: | |
: - >-------o------o---> -

But this circuit isn't as much fun. :>)

Thanks,
- Win

whill_at_picovolt-dot-com

If you want a 1V drop (for some reason???) then something like this:


Please view in a fixed-width font such as Courier.


LM185-ADJ
\
+---------|< |---------+
| \ | |
| +------+-------------------------+
| | | |
| / | |
| 470 | |
| / | |
| TIP42 \ | |
Vin----+-------- e c ---+-------+----------------------->Vout
| \ / | | |
| --- | | c
| 10K | 1N4148 | | 10K |/
+----/\/\---+---|>|----+ +--/\/\-----+---|
| | |\
| c e
| \| |
| |---+
| /| |
/ e /
470 | 1.3K
/ | /
\ | \
| | |
--- --- ---
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth
An e with a single dot over it, not the accent mark as in Jose'. I
think it's one of those pronunciation symbols.

The dot instead of a proper accent is a feature of whatever font you are
using. Look at it in Courier, Arial, Times New Roman.
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth
It looks (the outer part) exactly like one of those RS push on F
connectors - the male one (male center conductor, female housing)
but the center conductor is hollow and split as if the mating
connector would compress it and cause it to seize the mating
connector's center conductor which in that case would make the CIQ
(connector in question) female and female no thread. I couldn't
quite get a real idea of the size from the photo. Let's check
Pasternack.

You've described a Belling coax connector, I think. I don't know what
Pasternack is; a connector distributor?
The PAL connector in this book is a push on, but the CIQ can't be
this PAL connector. The one I'm looking at is male-female into
female-male with the male housing (which would correspond to the
CIQ) is .370" OD.

I just don't recognize the term 'PAL connector'.
I see 75 ohm MCX connectors where the jack corresponding to the CIQ
accepts a plug with a .147" OD housing - seisure and all.

I'd replace the friggin' thing with something I can lay hands on
easily. F connectors are common enough. Push ons I only use for
testing.

You should be able to get Belling-type connectors from Farnell/Newark.
 
A

Active8

Jan 1, 1970
0
I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth


The dot instead of a proper accent is a feature of whatever font you are
using. Look at it in Courier, Arial, Times New Roman.

Uh, sorry. It's pretty much the same in all three. The problem is,
at this high screen res it looks like a dot when in fact it's a
small slash.

Hey. If you ever have that prob (I use high res to make room for
large CADs so other apps without zoom are screwed) there a little
toy called Screen Loupe you can get. It's like having a magnifying
glass you can drag around the screen like a sceen color picker or
screen tape measure. Glad I remembered.
 
A

Active8

Jan 1, 1970
0
On Wed, 31 Dec 2003 14:29:34 -0800, Watson A.Name - "Watt Sun, Dark
Remover said:
This alt 0233 --> é looks to me like it's an accented e, as in Jose'
What's it look like to you?
------------------------
Hey Watson. You accidentally typed alt 0233 as you said instead of
alt 0223 like John said :)

Also, measure your connector & see if that MX 75 O [ <== this
little omega looks like a zero. arrrggghhh! No HTML in NNTP
either.]

connector I posted the OD on is close. And if you look back to the
link I posted on these extended ascii codes and other useful (?)
links, you'll see a connector reference link near the top.
 
A

Active8

Jan 1, 1970
0
I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth


You've described a Belling coax connector, I think. I don't know what
Pasternack is; a connector distributor?

Yes. www.pasternack.com It seems like they replace my catalog every
month. They have a UK disty: www.spectech.dial.pipex.com
I just don't recognize the term 'PAL connector'.

I thought PAL was/is (it is) a Europeeeen video standard. But there
is a PAL connector in the cat sure enough and it ain't what
Watson's got.
---------------------- ----------------------

You should be able to get Belling-type connectors from Farnell/Newark.

That's a good source for a lot of stuff. In Baltimore there's
Bainsville Electronics which is great, but I've only seen gold-
plated *kits* in the showcase. I'd wager they have it though.
 
M

mike

Jan 1, 1970
0
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.

My mistake. I read the subject line and the first line of the post
and mistakenly concluded that you wanted to use a regulated wall wart.
My baad.
mike
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Active8 <mTHISREMOVEcolasono@earth
I thought PAL was/is (it is) a Europeeeen video standard.

Indeed it is; it's the whole phrase 'PAL connector' that I don't
recognize.
 
R

Rich Grise

Jan 1, 1970
0
Hmm. When I hit alt-0233, I get one of these: !

Cheers!
Rich
 
A

Active8

Jan 1, 1970
0
Hmm. When I hit alt-0233, I get one of these: !

Cheers!
Rich

I can say with cetainty that I received an exclaimation point.

Hopeless?

Maybe not. If what I received is what you sent then the same code
is displaying the same character on the screen on both ends. JW and
I seem to have the same settings (odd because he said he used
winders 98), but you either have your locale set differently or
something I haven't though of.

I'm set for English(United State) - Regional and Language settings
in control panel.

Character map isn't working here for omega so I'd better blow it
off.
 
J

Jim Thompson

Jan 1, 1970
0
I can say with cetainty that I received an exclaimation point.

Hopeless?

Maybe not. If what I received is what you sent then the same code
is displaying the same character on the screen on both ends. JW and
I seem to have the same settings (odd because he said he used
winders 98), but you either have your locale set differently or
something I haven't though of.

I'm set for English(United State) - Regional and Language settings
in control panel.

Character map isn't working here for omega so I'd better blow it
off.

alt-0233 = é with NumLock ON or OFF, Win2K machine

...Jim Thompson
 
J

James Sweet

Jan 1, 1970
0
Active8 said:
I can say with cetainty that I received an exclaimation point.

Hopeless?

Maybe not. If what I received is what you sent then the same code
is displaying the same character on the screen on both ends. JW and
I seem to have the same settings (odd because he said he used
winders 98), but you either have your locale set differently or
something I haven't though of.

I'm set for English(United State) - Regional and Language settings
in control panel.

Character map isn't working here for omega so I'd better blow it
off.

Don't type the leading zero unless it's a 2 digit code, ASCII codes are all
3 digit from 000 to 255.
 
W

Watson A.Name - Watt Sun, Dark Remover

Jan 1, 1970
0
[snip]
I did this a while back. Replaced the 7806 in the wall wart with a 7805.
Wade

Yeah, but I've got four or five of them and I didn't want to crack
them open and then have to deal with the hassles of a case that's no
longer solidly sealed. And besides, they were only two bucks apiece.
I may bave paid more for their shipping.

Also, I bot four of the 6VDC unregulated wall warts at the same time,
and they have about 7 or 8V output unloaded. I don't think they have
enough voltage to allow a 7805 to work properly, at least not up to
200 mA, because the DC voltage drops down to near 6V at that current.

But 6VDC is a convenient value, used by a lot of equipment that has
four AA cells. So I have them just in case I want to 'electrify' one
of those ol' radios or whatever.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
Top