Driver to drive?

[Robert Lacoste]

For anyone interested, one of my last own articles on the "toaster oven"
subject is available online here :
http://www.circuitcellar.com/library/print/0704/Lacoste_168/index.htm

Friendly yours,
Robert

"Rich Grise" <richgrise@example.net> a écrit dans le message de news:
pan.2005.01.05.03.39.00.80892@example.net...

On Tue, 04 Jan 2005 11:25:26 -0600, Rob Gaddi wrote:

As bad of an idea as it sounds, I've had a lot of luck just using my
heat gun at its hottest setting and paste to solder thermal tabs. I
just design the pad with an array of the smallest vias that my fab can
support, lay a little dab of paste at the middle of the part with a
little more on a corner pin, and use the part to press it out across the
thermal contact, and then use the gun at a distance to slowly heat the
board, inching the gun closer until I see paste at the pin reflow. I
give it a few seconds after the pin goes, then switch the gun over to
cold and pray that I haven't roasted my chip. Hasn't failed yet.

Also, if you can provide heat from underneath to supplement the heat
from above it helps heat the board more evenly. Being surrounded by
scientists I've got access to chemistry hot plates, but a range and
cheap skillet should work just as well.

I'm still recovering from the shock I went into when people reported that
they routinely solder whole boards in one whump in a TOASTER
OVEN!!!!!!!!!!!

shudder

Rich

 

[Rhyanon]

Surely you didn't think I was that inexperienced?
Hehehehehe.........
--
"Don't worry, us witches will always be alright, dear. Remember, we happen
to other people..."

~Nanny Ogg~
--

"Locals call it Bear Mountain. This is because it was a _bare_ mountain, not
that it had a lot of bears on it. It was about as bare as a mountain could
be. Most trees gave out halfway to the top, only a few pines hanging on to
give an effect like that of a couple of pathetic strands teased across his
scalp by a baldie who won't own up. It was a place where Witches met. A fire
gleamed on the very crest of the hill. Dark figures moved in the flickering
light, as the moon coasted across a lacework of clouds. Finally, a tall,
pointy hatted figure said, "You mean _everyone_ brought potato salad?"


"Ed Murphy" <emurphy42@socal.rr.com> wrote in message
newsan.2005.01.06.01.37.55.962623@socal.rr.com...

On Wed, 05 Jan 2005 18:06:32 -0600, Rhyanon wrote:

Top posting rocks; one can conveniently folow up a reply, at least for
someone actually has the mental acumen to keep track of what's being
said.

Convenient != appropriate.

Easier to top post without scrolling through five hundred lines of
rehash.

Failure to trim quoted material is the real problem, and bottom posting
is not much better than top posting (especially when combined with
failure to trim). Interleaving replies amongst trimmed material is
appropriate.

Oh, and it riles anal retentive dipshits, as an added bonus. You
know what else I like to do? Add LOTS of sigs.

Yeah, yeah. Followup set.

 

[Parse Tree]

You deleted her!??! OH NO!

Clarence_A wrote:

"Rhyanon" <pissoff@uberbitch.com> wrote in message
news:10tqg7j9pq3q87c@corp.supernews.com...

Bah! Too much effort. If someone doesn't know what's going on or

being said

in a thread, they should "Rhyanon" off.



Generally I just delete top posters, "no intelligence there!"

 

[John Woodgate]

I read in sci.electronics.design that Rich Grise <richgrise@example.net>
wrote (in <pan.2005.01.07.05.06.26.883711@example.net&gt about 'Guy
Macon's adventures with ultrapure water', on Fri, 7 Jan 2005:

Yeah, great, but what about all those double bonds in the neck? Is it
some kind of buckytube?

No, it's just a highly unsaturated straight-chain hydrocarbon residue.
Perhaps more common in molecular gas clouds than on Earth, but it could
be made.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Winfield Hill]

Rodney Josey wrote...

On 24 Dec 2004 Winfield Hill wrote:

Jeroen wrote...

Referring to the post and thread from Winfield Hill regarding a
low noise DC/DC convertor of August 4th:

message-ID <cer27s014nf@drn.newsguy.com> and Google link:
http://groups-beta.google.com/group/sci.electronics.design/
browse_thread/thread/bb3edbc02ec23260

I'm having the same problem, so if there's a nice working circuit,
I'd like to see it

My project is on hold right now, since I lack the time to work on
this problem. An efficient simple 1MHz level-controlled sine-wave
power oscillator could be a critical part of the solution.

Here's a copy of my Aug 4, 2004 post:

My dc-dc converter specs: 5Vdc in, 1/2 to 1W max capability, four
simultaneous "unregulated" output voltages, small, very low noise,
high switching frequency (600kHz min to 5MHz better, etc.) -- by
"unregulated," I mean fixed input-to-output voltage ratios, 10-20%
tolerance allowed (if necessary I can adjust transformer windings,
and the loads will be constant).

I'm looking at Linear Technology's LT3439, almost exactly what I
need, push-pull transformer drive, etc., but yet misses by a mile.
http://www.linear-tech.com/prod/datasheet.html?datasheet=892

The LT3439 is one of LTC's line of slew-rate controlled low-noise
switching converters, but like the others it's limited to 250 or
300kHz, far too low for my application, in which I need to put the
switching noise well above my sensitive amplifier circuit's range.

Does anyone know a switching IC that's similar to the LT3439 but
runs at MHz frequencies? Maybe with sine-wave transformer drive?

Hi Winfield & Jeroen,

I know this may sound over-the-top, BUT if your circuit has the space,
you might want to consider doing away with the "noisy" DC/DC converters
and use a few NICAD or NIHM rechargeable batteries as the power sources
for the relevant voltages concerned. Higher current capacity batteries
would do for the higher current areas of your circuit with the added
advantage of NO NOISE or extra low noise from the power supply sections.
I would design the circuitry such that the batteries are 'recharged'
ONLY when the system is not being "actively" used - thereby transferring
any noise generating components to the system's IDLE or STANDBY periods.

Hope this helps..... Good Luck. Oz_Rod

That's a classic solution, but it's not practical in my application,
which is an unusual high-voltage STM preamp that needs +/-120V and
two to three other lower voltages. I fear that 240V of rechargable
batteries is a bit much!

Some good solutions were put forth in the thread referred to above.
Perhaps sometime I'll get back to that project. In the meantime I'm
using a small 1W dc-dc converter that creates common-mode noise at
80kHz. Anybody ever come across a three-winding common-mode choke?


--
Thanks,
- Win

 

[John Larkin]

On Fri, 07 Jan 2005 13:08:43 -0500, keith <krw@att.bizzzz> wrote:

On Fri, 07 Jan 2005 08:06:16 -0800, John Larkin wrote:

On Fri, 31 Dec 2004 18:43:40 +0000 (UTC), "Franz Heymann"
notfranz.heymann@btopenworld.com> wrote:


"Morituri-|-Max" <newage@sendarico.net> wrote in message
news:cO8Bd.27949$3v5.22225@fe2.texas.rr.com...
Franz Heymann wrote:
"Jim Thompson" <thegreatone@example.com> wrote in message
news:uvn9t0l92343vt559sr3hiqi4bp99sbtfu@4ax.com...

[snip]

Geesh, I doubt the French (or other OLD EUROPE countries) have
the
airlift capability or the military resources to quickly supply
the
damaged regions with supplies (certainly not nearly the
capability
of the US.)

So far I have not noticed much by way of american planes mixed up
with
the European planes which are actually flying in the aid.
You will, of course put up a magnificent effort, but only after
you
have been shamed into doing so.

Franz

As a former Air Force member I have to disagree here Franz,
respectfully. Also
if you are saying the USA has to be shamed into helping other
people, I submit
you do not understand americans. Bill Gates alone has endowed his
foundation
with $23 billion dollars and has pledged more than $7 billion
dollars in a few
years. So I again submit that the USA as a country has given far
more help to
the world than some people suggest.

I am talking specifically about aid to the disaster areas where the
tsunami wreaked such havoc. The following three numbers for aid
promised comes from this morning's Times:

USA 18 M UKP
UK 50 M UKP
France 31 M UKP
Spain 35 M UKP

The list is quite long, but the four I quoted makes my point quite
clearly. The USA is lagging badly. Undoubtedly it will get off its
arse after it has been publicly shamed. They troublr is that it takes
time to shame the USA, and the help is neede NOW.



This morning's paper showed a picture of a US Navy crewman carrying an
Indonesian kid. The US has sent in aircraft carriers, LHA ships, and
helicopters to help save lives in the short term. Long-term fund
raising and rebuilding won't help people who die in the first days and
weeks. The UN will no doubt do a lot of good, but they'll certainly
not do it quickly.

Not to mention the USS Abraham Lincoln carrier group off-shore. Sitting
there desalinating 400,000 gallons of water a day, with the crew
skipping showers to conserve potable water for the tsunami survivors. The
medical crew is ashore treating survivors and even the bakers are making
bread. Last report was that 10 of it's choppers were delivering supplies.
Of course this stuff doesn't cost anything.

I try not to be rah-rah nationalistic (really!) but I've been through
a few disasters myself - one tornado, several hurricanes, one serious
earthquake - and Americans are excellent in disasters. The most public
civility I've seen anywhere was in San Francisco in the days after the
'89 earthquake. 9/11 was like that in New York, too, from what I've
seen.

John

 

[Parse Tree]

Aunty Kreist wrote:

"Parse Tree" <account@domain.extension> wrote in message
news:qCADd.349882$O24.59754@news.easynews.com...

Aunty Kreist wrote:

"Parse Tree" <account@domain.extension> wrote in message
news:xamDd.302957$O24.51663@news.easynews.com...


These asshats need cluepons.


You are on a roll tonight! :-D

I don't like all these insinuations that I'm not positively precious
every night of the week. Hmmph.


You are, when you're not being a turd.

You're the turd, turd-head!

 

[John Fields]

On Fri, 07 Jan 2005 21:49:42 GMT, Richard the Dreaded Liberal
<eatmyshorts@doubleclick.net> wrote:

On Tue, 04 Jan 2005 09:24:11 +0100, Frank Bemelman wrote:

Q: What is the title of the thinnest book on Earth?
A: 200 years of German humor.

"Italian War Heroes"
"Jewish Business Ethics"
"Niggers I've Met While Yachting"

---
"The Wit and Wisdom of Rich Grise"?

--
John Fields

 

[Aunty Kreist]

"Parse Tree" <account@domain.extension> wrote in message
news:S7DDd.359287$lR6.60516@news.easynews.com...

Aunty Kreist wrote:
"Parse Tree" <account@domain.extension> wrote in message
news:qCADd.349882$O24.59754@news.easynews.com...

Aunty Kreist wrote:

"Parse Tree" <account@domain.extension> wrote in message
news:xamDd.302957$O24.51663@news.easynews.com...


These asshats need cluepons.


You are on a roll tonight! :-D

I don't like all these insinuations that I'm not positively precious
every night of the week. Hmmph.


You are, when you're not being a turd.

You're the turd, turd-head!

Takes one to know one, poopy brains!

 

[Rhyanon]

No.

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:SwfRK8J1Lw3BFwn4@jmwa.demon.co.uk...

I read in sci.electronics.design that Parse Tree
account@domain.extension> wrote (in <S7DDd.359287$lR6.60516@news.easyne
ws.com&gt about 'OT: Safe Riddles', on Fri, 7 Jan 2005:
Aunty Kreist wrote:


You are, when you're not being a turd.

You're the turd, turd-head!

Would you please take this delightful exchange of compliments to
alt.epithets.coprocrania?
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Rhyanon]

Tough shit. Go cower in your killfile blankie with your equally balless
friends.

"John Fields" <jfields@austininstruments.com> wrote in message
news:vv4ut0livqaiubjdcmc4p25gvs6b4cls7f@4ax.com...

On Fri, 07 Jan 2005 22:54:14 GMT, Parse Tree
account@domain.extension> wrote:

John Woodgate wrote:
I read in sci.electronics.design that Parse Tree
account@domain.extension> wrote (in
S7DDd.359287$lR6.60516@news.easyne
ws.com&gt about 'OT: Safe Riddles', on Fri, 7 Jan 2005:

Aunty Kreist wrote:


You are, when you're not being a turd.

You're the turd, turd-head!


Would you please take this delightful exchange of compliments to
alt.epithets.coprocrania?

Ok. I added it to the XPost.

---
That's not what he meant.

This is sci.electronics.design, not alt.juvenile.shitmongers, so if
you don't mind, please remove us from your list of crossposts.

--
John Fields

 

[Rhyanon]

My gawds, you're boring.

"Ed Murphy" <emurphy42@socal.rr.com> wrote in message
newsan.2005.01.07.01.09.16.497551@socal.rr.com...

On Thu, 06 Jan 2005 13:09:11 -0800, Charlie Gibbs wrote:

I take my philosophy from the same Lewis Carroll passage I used to use
as
a rebuttal to the Structured Programming zealots who wanted to chop
programs up into little subroutines jumping all over core:

The White Rabbit put on his spectacles. "Where shall I begin,
please
your Majesty?" he asked.

"Begin at the beginning, the King said, gravely, "and go on till you
come to the end: then stop."

That sounds like a heck of a good way to write something; it's certainly
the natural way to read it.

While zealots tend to run afoul of the "X is good, therefore more of X
is better" fallacy, *some* amount of chopping programs up into little
subroutines is appropriate:

1) When a routine is used in more than one place, there should be only
one copy of it, and calls to it from each place.

2) Sometimes, you only need/want the Big Picture view, and sane use of
subroutines gives you that view. Here's some sample pseudocode that
closely approximates one of my current projects.

main:
for each client
gosub calculate_setup_fee
gosub calculate_monthly_fee
gosub calculate_hold_fee
next
return

! Stop here for a minute, and think about the above section. Does
! it give you a decent Big Picture view of what this program does?

calculate_setup_fee:
if not(calculate_setup_fees) then return
! some logic omitted for brevity
gosub write_transaction
return

calculate_monthly_fee:
if not(calculate_monthly_fees) then return
! some logic omitted for brevity
gosub write_transaction
return

calculate_monthly_fee:
if not(calculate_monthly_fees) then return
! some logic omitted for brevity
gosub write_transaction
return

write_transaction:
! some logic omitted for brevity
return

 

[Mark Jones]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Aunty Kreist wrote:

This is alt.religion.wicca, not alt.nerdy.computer.geeks, so if
you don't mind, please remove us from your list of crossposts.

Haha. Don't ya just hate those nerdy computer geeks? But, not all
computer nerds are geeks... the same way that not all wiccans are
undercover Jahovah's Witnesses I suppose.



- -- At it's heart, all a fractal is is a simple unbalanced dynamic,
like cos(1/z)*z. A fractal is unbalanced in such a way that it can
never be solved, and the longer it is "computed", the more complex it
becomes. It is literally a twist or gotcha, on infinity.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.0 (MingW32)
Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org

iD8DBQFB36EkUoq45ERxHvoRAiFLAJ0XMUzKIbVvsIvGZnrrpvfQul0awwCbBqnQ
i5z5vicnArcqSnFauoBCeX0=
=IB6L
-----END PGP SIGNATURE-----

 

[mc]

Pity.


"Charlie Gibbs" <cgibbs@kltpzyxm.invalid> wrote in message
news:1375.868T920T12424113@kltpzyxm.invalid...

> X Top-posted messages will probably be ignored. See RFC1855.

 

[Anthony Fremont]

"Winfield Hill" <hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote in
message news:crp21l02gjm@drn.newsguy.com...

http://www.cnn.com/2005/TECH/01/03/cnn25.top25.innovations

CNN's list of the top 25 innovations of the last 25 years.

2. Cell phone
3. Personal computers

LOL, personal computers have been around longer than 25 years.

4. Fiber optics

this too
http://inventors.about.com/library/weekly/aa980407.htm

5. E-mail

so has this

6. Commercialized GPS
7. Portable computers

this too depending upon your interpretation of "portable"

8. Memory storage discs

this too

9. Consumer level digital camera
10. Radio frequency ID tags
11. MEMS
12. DNA fingerprinting
13. Air bags

offered in some GM regular production vehicles in 1975

14. ATM

close call on that one for being since 1980.

15. Advanced batteries

kinda subjective isn't it?

16. Hybrid car
17. OLEDs
18. Display panels
19. HDTV
20. Space shuttle
21. Nanotechnology
22. Flash memory
23. Voice mail

hmm..... they must mean digital

24. Modern hearing aids

too subjective, what is "modern"?

25. Short Range, High Frequency Radio

what do they mean by this? bluetooth?

The number one innovation will be announced on Sunday, January 16,
at 8 p.m. ET. What do you think it is?

I'm guessing that they'll say that it's the Internet when they probably
mean the web. But it probably should be the Mars rovers (or exploration
bots/autonomous vehicles) in general.

Seriously, couldn't they find 25 things that actually didn't occur until
after 1980? I would've thought that software patents would've been
included, especially since they've "revolutionized" the software
industry. ;-)

Does an innovation occur when someone actually implements an idea, or
only after it's mass acceptance? IMO, this is a poor list given the
fact that a "panel of technology leaders" came up with it. The ISS or
Hubble might have been worth mentioning.

 

[PaulCsouls]

On 8 Jan 2005 08:33:57 -0800, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

http://www.cnn.com/2005/TECH/01/03/cnn25.top25.innovations

CNN's list of the top 25 innovations of the last 25 years.

2. Cell phone
3. Personal computers
4. Fiber optics
5. E-mail
6. Commercialized GPS
7. Portable computers
8. Memory storage discs
9. Consumer level digital camera
10. Radio frequency ID tags
11. MEMS
12. DNA fingerprinting
13. Air bags
14. ATM
15. Advanced batteries
16. Hybrid car
17. OLEDs
18. Display panels
19. HDTV
20. Space shuttle
21. Nanotechnology
22. Flash memory
23. Voice mail
24. Modern hearing aids
25. Short Range, High Frequency Radio

The number one innovation will be announced on Sunday, January 16,
at 8 p.m. ET. What do you think it is?

The left turn signal on traffic lights. You use to have to wait for
the light to just turn red and sneak throught before the other light
turned green. Now its easy. The guy who came up with that deserves a
medal. It's either that or superconductors.

 

[Scott Miller]

Thank you. Can you tell me what kind of diodes D1 and D2 are, and
what are the values of C5 and C6?

D1 and D2 are 1N4007's, C5 C6 and C9 are 0.0022 uF.

This is a strange sort of step up supply, what with the full wave
doubler using both swings from the transformer, but the primary driven
only one way.

Hmm, don't ask me... I cribbed that from this design -
http://www.cbtricks.com/members/AB7IF/bgc/bgc_page2.gif - or one like it.
I've seen the same design a few times. I substituted the BS170 FET for an
obsolete BJT on the primary - seems to work just as well.

Seems to me that the supply doesn't need to be terribly efficient, because
if you do it right it'll have a low duty cycle. C9 stays charged for a long
time at normal radiation levels. It'll draw maybe 100 uA every count for a
very short period - under 100 usec, I think. With the tubes I'm using,
normal background radiation is around 20 counts/minute.

Anyway, like I said, we learned about driving transformers with AC.. I don't
know exactly what the secondary output is supposed to look like when the
primary is driven only one way with a square wave.

Scott

 

[Rodney Josey]

On Fri, 7 Jan 2005 16:02:26 -0800, DaveC <me@privacy.net> wrote:

Switch closure needs to be monitored. On one side of the switch is mains
voltage (120vac); on the other, the load.

Simple enough to monitor the switch's status: when mains voltage appears on
the load side, it's closed.

But how to monitor this switch during a power failure? I'd like to be able to
report to an alarm sensor's input (simple current loop) when this switch
closes, whether mains power is applied to the switch, or power has failed.

When power fails, I could put a simple battery and coil of a l.v. relay
across the switch. But when mains voltage reappears, removing the battery
circuit in time becomes a bit risky.

How best to accomplish this task? Ideas?

Thanks,
------------------------------------------------------------------------------------

Hi Dave,

I think I may have come up with a circuit to meet your requirements....

Unfortunately it is a bit too much to acurately lay it out using AACircuit (www.tech-chat.de) which
is what I generally use for posting to this N.G. - so I've split it into smaller sections.

If I'm reading what you say in your posts right - your system comprises a 120VAC submersible pump
(in a well) controlled by a float switch (which is in series with the pump) - AND - you want to be
able to monitor the state of the float switch - AND - set an alarm input depending on whether the
switch is closed or open - IRRESPECTIVE of whether the 120VAC power is on or off ????

QUESTION: what is the max current draw of the pump motor ?

If I'm correct with my summizing, then the circuit I propose would certainly perform the task plus
give some added FLEXIBILITY to how you can use it. The circuit uses around 35-40 components
mounted on a PCB and along with a 4 x AA NI-MH (or NICAD) batteries (1.5V ea @ 2300mAh = 6V DC)
should fit into a 8"x 6"x 3" plastic enclosure case and cost approx $75.00 or less (depending on
where you purchase the components).

The circuit concept is: If the in-well pump is say 120VAC @ 10A then the minimum 'operating' voltage
before the pump motor stalls is probably around 60VAC @ 5-6A - so at lower AC the motor doesn't turn
- however - the motor windings will still pass low voltage / low current AC (the motor just wont
turn) - THUS - this effect can be used to easily determine the "state" of the in-line float switch -
e.g.. if the low voltage / low current AC flows thru the motor - then the float switch is closed -
if not - the float switch is open - VOILA - a method to determine the float switch "state". NOTE:
this will work whether the normal AC to the pump motor is on - or - off (actually 'off' manually -
or - when mains power fails due to a blackout or low power condition - brownout). NOTE: AC voltage
is used instead of DC because AC motors may have internal 'capacitive' coupling as well as inductive
- DC is generally 'blocked' by such coupling methods - AC will pass thru.

A transformer-less AC-to-DC 12V DC power supply across the Mains active and neutral lines drives 2 x
10A DPDT 12vdc coil relays - 1 relay in the mains active line - 1 in the mains neutral line
(ISOLATES the 'outside' well mains wires from the 'inside' well mains wires). A 3rd low power SPDT
relay 12vDC coil is also operated by this power supply and is used to turn on / off the battery
power to the 'control' circuit. You'll need to work out the component values to suit.

---------------------------------------------------------------------------------------------
MAINS RELAY SUPPLY:

Active (outside .------.
Mains Well) RLY1|--o\ |
120V o------+-------+-----------------------------------------|--o o-|--+---------o 'ACTIVE'
AC | | | | | (inside
+ .-. +--------|--o\ | | Well)
--- | | R1 | _____|_-o o-|--+
C1 --- | | | | | )| |
+ '-' | | _|_)| |
| | | | |'------'
| | | | |
| .-. +---|---|--------------------o Txfr1
| | | R2 | |
| | | | +---+
| '-' | |
| | +--|<---+
+-------+ | D2 |
| | |
.-. .-. |
| | R3 | |R4 |
| | | | |
'-' '-' |
+ | |
+----+----+ | +----o Gnd To Relay 3
| ~ | | |
- V | |
^ - +-------+-------+----Xa-----+--+----|----o +12V To Relay 3
DC | BR1 | | |+ + | |
+-----+ +---+ --- z | |
| | | DC --- A 12V .-. |
| V - | C2 + Zener R5| | |
| - ^ |470uF | | | |
| | ~ | |25V | '-' |
| +----+----+ | | | |
| | | | | |
+----------|----------------+-------+-Xb-Xc-+------+----+
| | |
| +-->|--+ .------.
120V | | D3 | |--o\ |
AC o---------------+-----------------------------------------|--o o-----+--------o 'NEUTRAL
Neutral | | | | | (inside
Mains | +-|-|--o\ | | Well)
(outside | | |_|_-o o-|---+
Well) | | | )| |
|____|___|_)| |RLY2 +----o Isense-B
| '------' |
| |
+------------------+

NOTE: Xa, Xb, Xc = OPTION

(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)

----------------------------------------------------------------------------------------------------
Whilst ever the mains is on - the relays are operated via the 12vDC - letting the mains AC thru to
the float switch & pump in the well. If the mains is turned off (manually) - or - fails (blackout),
the relays de-activate. The 3rd relay turns on the 'control' circuit - when power fails (or is
turned off manually).

The 'control' circuit (shown below) is formed as a battery operated low-voltage (5v DC) DC-to-AC
converter providing around 15-18VAC @ 100-150mA which is coupled to the 'inside' well mains wires by
a small low current step-up transformer via one pole of the each of the "isolation" relays. An
PICAXE-08M microcontroller is at the heart of the converter / monitor - 2 outputs drive MTP3055E
MOSFETS which switch 0v to one side of upper & lower windings (secondary) of the transformer - +5vdc
is fed to the centre tap of the windings. The output winding (primary) steps up the generated
voltage to around 15-18VAC @ approx 100mA. This generated AC voltage now flows - thru the 'active'
line relay - to the float switch (if closed) - thru the pump motor windings - to the 'neutral' line
relay - thru a 'current' detector - back to the other side of the transformer output winding.

-----------------------------------------------------------------------------------------------
CONTROL CIRCUIT:

+--------+ +--------+-------|<-----o +5V
| | | | Dx
| | --- |
Txfr-A | +--| --- 100n |
o | Q2 | | |
| | +->|| ___ === |
| +--+ +--|+---|___|--+ 0V |
+--. | | Ra | | U1
)|.---+ | | .------o-----.
TXFR )|(______o +5V === | | +ve | ___ Rc
)|( 0V +------oP4 P0o----|___|------o 'Alarm O/P'
)|'---+ | | ___
+--' | +----------oP2 P1o----|___|---+
| +-----+ | | | Rd |
| | | +----oP3 Sio--+ |
o | | | | 0V | | .------.
Txfr-B +--| | | '------o-----' .-. | | >
(Isense-A) Q1 | | | | | | | | < Opto_2
+->|| ___ | | | | |Re | V > Led
+--|+----|___|---+ | === '-' | - < (Option)
| Rb | 0V | | | >
| | | '------
=== o === |
0V 'sense' 0V |
===
0V
Q1,Q2 = MTP3055E FET

U1 = PICAXE-08M

Dx = IN4004

Resistors = to suit

(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)
-----------------------------------------------------------------------------------------------------

The 'current' detector is shown below - when sufficient current flows thru the resistor Rx, the
optoisolator's led turns on. The opto's output transistor turns on - pulling the 'sense' line low.
THUS: if the float switch is closed - the 'sense' line is low; if the float switch is open - the
'sense' line is high.

------------------------------------------------------------------------------------------------
CURRENT SENSE DETECTOR CIRCUIT:


Txfr-B (Isense-A)
o
|
|
|~ +----------o +5V
+-+-+-------|--------+ |
+ | | | +
- V | .-. .-.
^ - .-.Rx | |47r | |1K0
Diodes | | | | | | | |
- +---+ + | | '-' '-'
| | '-' + +
V - | | +-----+----------o Sense
- ^ | .-+-------+--.
| | | | V |/ |
+-+-+-------+ | - -| |
|~ | | | |> | OPTO_1
| | | | + |
| | '-+-------|--'
| | | |
| +--------+ +----------------o 0V
|
o (Isense-B)
AC Neutral
via Relay

(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)

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

The 'sense' line is monitored by 'IN3' pin of the PICAXE-08M chip. A 3rd 'output' of the PICAXE-08M
is then used as the "alarm" drive out either via a 2nd OPTO - or - via a transistor....

------------------------------------------------------------------------------------------------
BATTERY SUPPLY:


.------. Dv
+ve | /o-|---->|-------o +5V
o----------------|--o o-| (control)
| ____|__ |
| | | )| | Rly3
--- | _|__)| |
Bat - | | '------'
--- | |
6V - | +------+
2300mAh | | |
NI-MH | | |
o-------------------------------------o 0V
-ve | |
| |
| |
+----|<---+
| Ds |
| |
| |
o ===
+12V Gnd
(Relays)


(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)

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

FLEXIBILITY:

The "flexibility" I mentioned earlier: using the PICAXE micro gives you the option (with a few extra
components in the "mains" relay power supply circuit (1 x resistor, 1 x opto, 1 x MTP3055E FET)) -
to 'delay' the turn-on of the "mains" to the float switch / pump motor AFTER the float switch is
detected as 'closed'. Example: if the float switch is detected as 'open' - the water level in the
well is below the "minimum" pump activate level. When the float switch is detected as 'closed',
you may want to delay the pump turn-on to allow time for the water level to rise sufficiently to
provide a suitable pump 'head' flow. A 'delay' sequence can be programmed in the PICAXE micro to
achieve this. An additional option: extremely low power consumption from the batteries by using the
PICAXE 'sleep' function :- testing of the 'sense' loop could be done once every 1-2 minutes (should
take about 3-5 seconds for a sampling) - in between each 'test' the micro could be placed in sleep
mode - conserving power. This could give several months of use from a set of batteries.

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

OPTION: Insert the components below into the "MAINS RELAY SUPPLY CIRCUIT" above where indicated.


'Xa'
o
|
|
|
.-.
| |Rm
| |
'-' +----o 'Xc'
| |
+-------+ |
.-------. | |--+

| | | ||
Opto_2 < |/ | | ||<-+ Q3

O/P > -| | +--+|--+
< |> | |
(Option) > | | |
'-------' |
| |
'Xb'o---------+--------------+


(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)

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

The PICAXE series of chips are very easy to program and are very low in cost - MUCH BANG for little
BUCKS - in such small packages.

I hope this extra long post is helpful ??

Best of luck with your project.

Oz-Rod

 

[Winfield Hill]

Ken Smith wrote...

You may find it works better if the inductors are lossy. Something
has to eat the energy in the spikes.

Hmm, ferrite beads may be better.

Also, can you put a capacitor as shown:

[Modified]
. input power noisy CM choke floating
. +15 10uH dc-dc 50uH 10uH 180 power
. ---+-----####---+---| |---#####----####--+--/\/\--+---
. === 10uF _|_ | | ===== === 10u === 0.82
. +--, 10 --- | y |-+-#####--+-------+---z----+-- x
. === | | | | ! ===== | === ===
. ---+--|--####---+---|_____|---#####--|-####--+--/\/\--+---
. -15 | ! |
! --- !
! --- 0.1 !
! ! !
! GND !
! !
. | HV |\__Ro 5.7k___| STM tip-bias
. | opamp |/ |
. | ,--||--' 3uF 250Vac
. -------+------ Ground ---------+--------------------------

Yes, I tried that, or more accurately a portion of the 3uF, a
0.68uF film cap was more helpful in parallel with the 2.3uF of
unpolarized electrolytic at point x, than if placed at point y.

Winfield wrote...

Despite the output CM choke, the problem continues to be 50ns
80kHz repetition-rate charge spikes into the STM tip-bias, at
point x, creating a small but highly-damaging 80kHz sine wave.

What roughly frquency of the energy in the spike? ie: Does it
look like a like a blast of 1MHz, 10MHz or what.

The normal-mode noise on the +/-15V outputs is a single ring of
pulse about 150mV in amplitude lasting about 200ns. Although I
know well about common-mode noise, I hadn't earlier thought to
set up and measure its energy. Actually, it's charge I need to
measure. I did calculate how much current it must be to create
the observed 250uV 80kz sine wave on the 3uF at point x (actually
calculated from the observed STM preamp output), and the number,
380uA, seems far too high. BTW, I'm well aware of the necessity
for careful probing techniques, and have double-checked this.
I've also determined that radiated RFI from the switching module
is not the problem. I'll be going back to the bench on this one.


--
Thanks,
- Win

 

[John Woodgate]

I read in sci.electronics.design that markzoom <markzoom@digiverse.net>
wrote (in <7172c4fd.0501090729.17d84f6e@posting.google.com&gt about
'Quick power supply question', on Sun, 9 Jan 2005:

Does the symbol, a solid line with a dotted line over it, denote an
unregulated or a regulated supply?

Officially, it just means 'DC'. People seem to think they can allocate
new meanings to these IEC 60417 symbols and everyone will be informed of
the changed meanings by telepathy.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk