Alternative Power sources - A wall-wart alternative

Author

A wall-wart alternative

nicksanspam@ece.villanova.edu

2006-01-05, 2:21 am

I finally got tired of replacing the 2 C-cells in a clock with a moving
pendulum, so I measured the current (3 volts at 340 microamps) and built
a charge pump like this, viewed in a fixed font:

0.047 uF @400 V
|| |
-----------||--------------------->|------------>
|| | | |
| | 3V
120 VAC --- --- to clock
^ _
0.047 uF @400 V | |
|| | |
-----------||----------------------------------->
||

I used two caps in case one shorts and for some ground isolation. The diodes
are 5.1 V zeners ($1.29 for 2 at Radio Shack) to limit the clock voltage if
someone unplugs the batteries. This circuit supplies 390 microamps. I hope
to avoid replacing the batteries until their shelf life runs out in 2012 :-)

This could be useful for lots of low-power stuff, eg smoke detectors.

Nick

malc

2006-01-05, 5:21 am

nicksanspam@ece.villanova.edu wrote:
> I finally got tired of replacing the 2 C-cells in a clock with a moving
> pendulum, so I measured the current (3 volts at 340 microamps) and built
> a charge pump

We used to use a similar circuit for powering electronic thermostats
when I worked for Potterton Boilers here in Blighty. We used just one
Class X capacitor feeding a 24V zener and smoothing capacitor.

I also used to use one for charging the NiCads in my caving lamp. Of
course I made the classic mistake of plugging it in then picking up the
crocodile clips to connect onto the battery (rather than connecting
onto the battery then plugging in). Rectified 240V doesn't half hurt.

--
Malc

hallerb@aol.com

2006-01-05, 9:21 am

I used a ac adapter of the proper voltage to charge a bunch of D sixed
nicads to run my answering machine during power failures. it was like a
UPS uninterruptiple power supply.

my old machine would spaz with any power failure

The batteries went bad after 6 years, my new machine a different
voltage with a battery backup of memory, so I dont use this anymore

hallerb@aol.com

2006-01-05, 9:21 am

I hope you are using rechargable batteries!

Regulart alkaline or others may dry out, overheat and start a fire!

USE ONLY RECHARGABLE BATTERIES IN THIS APPLICATION!

Al Bundy

2006-01-05, 10:21 am

I like the concept, but it's hardly worth doing if you value the
portability of the object and batteries can be had so cheaply.

nicksanspam@ece.villanova.edu

2006-01-05, 10:21 am

<hallerb@aol.com> wrote:

>I hope you are using rechargable batteries!

NO!

>Regulart alkaline or others may dry out, overheat and start a fire!

How much will they overheat if overchaged at 3Vx50uA = 150 microwatts? :-)

>USE ONLY RECHARGABLE BATTERIES IN THIS APPLICATION!

NO!

Happy new year,

Nick

meow2222@care2.com

2006-01-05, 11:21 am

nicksanspam@ece.villanova.edu wrote:

> I finally got tired of replacing the 2 C-cells in a clock with a moving
> pendulum, so I measured the current (3 volts at 340 microamps) and built
> a charge pump like this, viewed in a fixed font:
>
> 0.047 uF @400 V
> || |
> -----------||--------------------->|------------>
> || | | |
> | | 3V
> 120 VAC --- --- to clock
> ^ _
> 0.047 uF @400 V | |
> || | |
> -----------||----------------------------------->
> ||
>
> I used two caps in case one shorts and for some ground isolation. The diodes
> are 5.1 V zeners ($1.29 for 2 at Radio Shack) to limit the clock voltage if
> someone unplugs the batteries. This circuit supplies 390 microamps. I hope
> to avoid replacing the batteries until their shelf life runs out in 2012 :-)
>
> This could be useful for lots of low-power stuff, eg smoke detectors.
>
> Nick

Caps do have a failure mode, so a series safety R is normally included
with these type circuits.

If your ac supply is polarised, you'd be a bit safer putting one cap in
the live than one in each pole, as the output will then be at apx earth
potential, though not isolated. As it stands its semi-live.

NT

Clark

2006-01-05, 3:21 pm

Looks like a shock hazard to me.

<meow2222@care2.com> wrote in message
news:1136474092.522774.256340@f14g2000cwb.googlegroups.com...
> nicksanspam@ece.villanova.edu wrote:
>
>
> Caps do have a failure mode, so a series safety R is normally included
> with these type circuits.
>
> If your ac supply is polarised, you'd be a bit safer putting one cap in
> the live than one in each pole, as the output will then be at apx earth
> potential, though not isolated. As it stands its semi-live.
>
>
> NT
>

William P.N. Smith

2006-01-05, 4:21 pm

"Clark" <CP@comcast.net> wrote:
>Looks like a shock hazard to me.

It is, but it's a current-limited shock hazard. Never pass UL, but it
works. Well, until the wrong cap shorts, then someone dies. 8*|

Jeff Wisnia

2006-01-05, 5:21 pm

Clark wrote:
> Looks like a shock hazard to me.
>
>
>
> <meow2222@care2.com> wrote in message
> news:1136474092.522774.256340@f14g2000cwb.googlegroups.com...
>

And at that low a current, why not ferget the caps and just use a couple
of 150K resistors? The additional power loss will hardly spin your
meter off the wall and you'll avoid the possible cap failure problem.

Jeff (Ducking and slinking off...)

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."
[color=darkred]
>
>
>

nicksanspam@ece.villanova.edu

2006-01-05, 6:21 pm

William P.N. Smith <news05@compusmiths.com> wrote:

>"Clark" <CP@comcast.net> wrote:
>
>It is, but it's a current-limited shock hazard. Never pass UL, but it
>works. Well, until the wrong cap shorts, then someone dies. 8*|

It might pass UL, in its "double-insulated grandfather clock" :-)

Nick

JeffM

2006-01-05, 8:21 pm

>>I...built a charge pump like this, viewed in a fixed font:
>
>Caps do have a failure mode,
>so a series safety R is normally included with these type circuits.
> NT (meow2222 @ care2.com)

It should be noted that such *series capacitor* devices
were outlawed for commercial products long ago in Europe.
As the Big Cat notes, without a resistor to limit things,
failures are usually dramatic.

Don K

2006-01-05, 8:21 pm

<nicksanspam@ece.villanova.edu> wrote in message news:dpibig$oc@acadia.ece.villanova.edu...
>I finally got tired of replacing the 2 C-cells in a clock with a moving
> pendulum, so I measured the current (3 volts at 340 microamps) and built
> a charge pump like this, viewed in a fixed font:
>
> 0.047 uF @400 V
> || |
> -----------||--------------------->|------------>
> || | | |
> | | 3V
> 120 VAC --- --- to clock
> ^ _
> 0.047 uF @400 V | |
> || | |
> -----------||----------------------------------->
> ||
>
> I used two caps in case one shorts and for some ground isolation. The diodes
> are 5.1 V zeners ($1.29 for 2 at Radio Shack) to limit the clock voltage if
> someone unplugs the batteries. This circuit supplies 390 microamps. I hope
> to avoid replacing the batteries until their shelf life runs out in 2012 :-)
>
> This could be useful for lots of low-power stuff, eg smoke detectors.
>
> Nick

It seems counter-productive to build booby-traps into smoke detectors
and the like.

Unlike a wall-wart, it will require special precautions not to accidentally
touch anything when you go to change the battery or maybe even set the time
on a clock. You will never know whether a capacitor has shorted and whether
you might be killed the next time you provide a path to earth ground.

There's nothing to limit the current when capacitors fail, so that failure
will cause a fire. There's no transient voltage protection, so the odds
of capacitor over-voltage failure is pretty high.

Don

SolarFlare

2006-01-05, 10:21 pm

What is your child's life worth when they need to steal
a battery for their latest toy?

That's just idiotic.

"Al Bundy" <MSfortune@mcpmail.com> wrote in message
news:1136469512.174420.246080@z14g2000cwz.googlegroups.com...
> I like the concept, but it's hardly worth doing if
you value the
> portability of the object and batteries can be had so
cheaply.
>

SolarFlare

2006-01-05, 10:21 pm

2 Lithium batteries would be safer, cheaper, less work,
last longer and much more reliable.

Just a moronic idea

"JeffM" <jeffm_@email.com> wrote in message
news:1136505421.300695.203990@f14g2000cwb.googlegroups.com...
fixed font:[color=darkred]
clock[color=darkred]
type circuits.[color=darkred]
>
> It should be noted that such *series capacitor*
devices
> were outlawed for commercial products long ago in
Europe.
> As the Big Cat notes, without a resistor to limit
things,
> failures are usually dramatic.
>

SolarFlare

2006-01-05, 10:21 pm

It's a fire hazard and if your insurance finds out you
may be out on the street without a mortgage.

<nicksanspam@ece.villanova.edu> wrote in message
news:dpk47m$8ta@acadia.ece.villanova.edu...
> William P.N. Smith <news05@compusmiths.com> wrote:
>
Never pass UL, but it[color=darkred]
someone dies. 8*|[color=darkred]
>
> It might pass UL, in its "double-insulated
grandfather clock" :-)
>
> Nick
>

Vaughn

2006-01-05, 10:21 pm

"Don K" <dk@dont_bother_me.com> wrote in message
news:DOudnfmoYshxKCDeRVn-pA@comcast.com...
>
> Unlike a wall-wart, it will require special precautions not to accidentally
> touch anything when you go to change the battery or maybe even set the time
> on a clock. You will never know whether a capacitor has shorted and whether
> you might be killed the next time you provide a path to earth ground.
>
> There's nothing to limit the current when capacitors fail, so that failure
> will cause a fire. There's no transient voltage protection, so the odds
> of capacitor over-voltage failure is pretty high.

A few points of data:

1) Even transformers can (and do) short out.

2) Switching power supplies do not necessarily have transformers, (more and
more wall warts are switchers, they are far more efficient)

3) Transient voltage protection can be added to virtually any circuit.

4) With proper circuit design, there can be something to limit current when a
capacitor fails.

5) With proper circuit design and component selection, the danger of a capacitor
failing can be infinitesimal.

Vaughn

>
> Don
>

SolarFlare

2006-01-05, 10:21 pm

2 Lithium C cells would be cheaper, less time
consuming, longer lasting, safer, easier, less fire
hazard, wouldn't nullify your home insurance and more
reliable.

"Vaughn" <vaughnsimonHATESSPAM@att.fake.net> wrote in
message
news:Kdkvf.228563$qk4.112062@bgtnsc05-news.ops.worldnet.att.net...
>
> "Don K" <dk@dont_bother_me.com> wrote in message
> news:DOudnfmoYshxKCDeRVn-pA@comcast.com...
precautions not to accidentally[color=darkred]
maybe even set the time[color=darkred]
has shorted and whether[color=darkred]
path to earth ground.[color=darkred]
capacitors fail, so that failure[color=darkred]
protection, so the odds[color=darkred]
>
> A few points of data:
>
> 1) Even transformers can (and do) short out.
>
> 2) Switching power supplies do not necessarily have
transformers, (more and
> more wall warts are switchers, they are far more
efficient)
>
> 3) Transient voltage protection can be added to
virtually any circuit.
>
> 4) With proper circuit design, there can be something
to limit current when a
> capacitor fails.
>
> 5) With proper circuit design and component
selection, the danger of a capacitor
> failing can be infinitesimal.
>
> Vaughn
>
>
>
>

RoughRider

2006-01-05, 11:21 pm

See response point by point....
"Vaughn" wrote in message A few points of data:
>
> 1) Even transformers can (and do) short out.
They fail and usually the primary blows open. But short from primary to
secondary is rare.... I've never seen it with wall-warts.... I have seen
this with pole top distribution cans after a lightning strike.
>
> 2) Switching power supplies do not necessarily have transformers, (more
> and more wall warts are switchers, they are far more efficient).
You are thinking about buck or boost designs that are used with DC-DC
voltage conversion. While many of these also use a transformer for
isolation, cheaper ones where the ground doesn't have to be inverted or
isolation isn't required don't have a transformer, just an inductor.
Anything connected to a wall outlet will have a transformer for isolation
and to provide a ratiometric voltage reduction for the output side. And
since it is switching at 100kHz or higher, the transformer has a ferrite
core and is very small (unlike an iron core operating at 60 Hz).
>
> 3) Transient voltage protection can be added to virtually any circuit.
Sure. But that will require a fuse as well to open and protect the
conducting MOV from self destruction. For the low current application
described in this thread, a (diode) or other semiconductor based OVP would
be more appropriate to be used with a resistor.
>
> 4) With proper circuit design, there can be something to limit current
> when a capacitor fails.
True. This entire concept is a throw back to the
transformerless/batteryless Rogers tube radio. Remember even old TV's had a
HOT chassis. Every home with a TV or tube radio had one of these. I used
to play a game with my sister by holding the metal TV tuner dial and an
adjacent speaker lead from a radio. The harder one pressed, the more
current would flow. The winner was the one that could make their muscles
visibly twitch! But standards, liability, insurance, experience being what
it is, we are a lot smarter these days not to make products this way.
>
> 5) With proper circuit design and component selection, the danger of a
> capacitor failing can be infinitesimal.
Of course. But many of us get components from a surplus store, so who knows
why the caps are there in the first place. ??

Bottom line is that the concept is electrcially sound. Is it safe? No. Is
anything likely to go wrong? No. Remember, it takes a collection of
mistakes to create a catastrophy.

Bye!

George Ghio

2006-01-06, 1:21 am

RoughRider wrote:
> See response point by point....
> "Vaughn" wrote in message A few points of data:
>
>
> They fail and usually the primary blows open. But short from primary to
> secondary is rare.... I've never seen it with wall-warts.... I have seen
> this with pole top distribution cans after a lightning strike.
>
>
> You are thinking about buck or boost designs that are used with DC-DC
> voltage conversion. While many of these also use a transformer for
> isolation, cheaper ones where the ground doesn't have to be inverted or
> isolation isn't required don't have a transformer, just an inductor.
> Anything connected to a wall outlet will have a transformer for isolation
> and to provide a ratiometric voltage reduction for the output side. And
> since it is switching at 100kHz or higher, the transformer has a ferrite
> core and is very small (unlike an iron core operating at 60 Hz).
>
>
> Sure. But that will require a fuse as well to open and protect the
> conducting MOV from self destruction. For the low current application
> described in this thread, a (diode) or other semiconductor based OVP would
> be more appropriate to be used with a resistor.
>
>
> True. This entire concept is a throw back to the
> transformerless/batteryless Rogers tube radio. Remember even old TV's had a
> HOT chassis. Every home with a TV or tube radio had one of these. I used
> to play a game with my sister by holding the metal TV tuner dial and an
> adjacent speaker lead from a radio. The harder one pressed, the more
> current would flow. The winner was the one that could make their muscles
> visibly twitch! But standards, liability, insurance, experience being what
> it is, we are a lot smarter these days not to make products this way.
>
>
> Of course. But many of us get components from a surplus store, so who knows
> why the caps are there in the first place. ??
>
> Bottom line is that the concept is electrcially sound. Is it safe? No. Is
> anything likely to go wrong? No. Remember, it takes a collection of
> mistakes to create a catastrophy.
>
> Bye!
>
>

Nick Pine + Tools = Danger.

This is just another example.

Vaughn

2006-01-06, 7:21 am

"RoughRider" <Post@thisnewsgroup.com> wrote in message
news:zSkvf.2964$H37.435092@news20.bellglobal.com...
> See response point by point....
> Bottom line is that the concept is electrcially sound. Is it safe? No. Is
> anything likely to go wrong? No.

You made a collection of pretty good points, which collectively fail to
logically lead to your conclusion that the circuit is inherently unsafe.

Bye yourself
Vaughn

nicksanspam@ece.villanova.edu

2006-01-06, 8:21 am

Don K <dk@dont_bother_me.com> wrote:

><nicksanspam@ece.villanova.edu> wrote:

[color=darkred]
>Unlike a wall-wart, it will require special precautions not to accidentally
>touch anything when you go to change the battery...

And it has battery backup :-)

>There's nothing to limit the current when capacitors fail, so that failure
>will cause a fire.

I doubt that. The diodes will probably open, and I used really skinny wire.

>There's no transient voltage protection, so the odds of capacitor over-voltage
>failure is pretty high.

Or diode damage. So... I added a 1K series resistor. This would also work:

0.022 uF @400 V*
|| |
-----------||--------------------->|------------>
|| | | |
| | 3V
120 VAC --- --- to clock
^ _
| |
10K | |
-----------www---------------------------------->

*Digikey's $29.95 M400-KIT-ND 400 V capacitor assortment contains
10 of these, along with 10 of 14 other values from 0.001 to 0.1 uF.

Nick

SolarFlare

2006-01-06, 7:21 pm

Don't go against the "Collective" You too will be
assimilated.

"George Ghio" <AKA@nomailhere.com> wrote in message
news:43bdf6a4_4@news.chariot.net.au...
>
>
> RoughRider wrote:
short from primary to[color=darkred]
wall-warts.... I have seen[color=darkred]
lightning strike.[color=darkred]
transformers, (more[color=darkred]
more efficient).[color=darkred]
are used with DC-DC[color=darkred]
transformer for[color=darkred]
have to be inverted or[color=darkred]
just an inductor.[color=darkred]
transformer for isolation[color=darkred]
the output side. And[color=darkred]
transformer has a ferrite[color=darkred]
operating at 60 Hz).[color=darkred]
virtually any circuit.[color=darkred]
and protect the[color=darkred]
current application[color=darkred]
semiconductor based OVP would[color=darkred]
something to limit current[color=darkred]
Remember even old TV's had a[color=darkred]
had one of these. I used[color=darkred]
TV tuner dial and an[color=darkred]
pressed, the more[color=darkred]
could make their muscles[color=darkred]
insurance, experience being what[color=darkred]
products this way.[color=darkred]
selection, the danger of a[color=darkred]
surplus store, so who knows[color=darkred]
sound. Is it safe? No. Is[color=darkred]
takes a collection of[color=darkred]
>
> Nick Pine + Tools = Danger.
>
> This is just another example.

meow2222@care2.com

2006-01-07, 4:21 am

nicksanspam@ece.villanova.edu wrote:
> Don K <dk@dont_bother_me.com> wrote:
[color=darkred]
>

same precautions as any mains device, all nonisolated parts must be
protected from touch. The danger with this system lies not in the
design itself, but in putting into the hands of people that dont know
what theyre doing with it, and might use it like a wall wart. Since the
safety R has been added, it can be used perfectly safely, but only when
its issues are understood and appropriately addressed.

Smoke detectors could be used hapily with it if a screw were added to
prevent opening.

[color=darkred]

X rated capacitors use fusible coatings, so a short causes a burn out
of the conductor around the short. The overall capacitance is not
noticeably affectde, IOW its self healing.

[color=darkred]
> I doubt that. The diodes will probably open, and I used really skinny wire.

Very fine wire sounds like effective fusing to me.

>
> Or diode damage. So... I added a 1K series resistor. This would also work:

Yes, though again you need the R and C in the live. The days where you
could scatter proetction devices between L and N lines is long gone -
at least in our part of the world anyway.

If youre using non polarised plugs on this, you'd need an R in both
lines imho. These need to be safety Rs, not the kind that catch fire
and carbonise.

Personally I'd make the R as high as is possible, so it responds
effectively to any fault throughput incease.

NT

nick pine

2006-01-07, 4:21 am

> 0.022 uF @400 V*
> || |
> -----------||--------------------->|------------>
> || | | |
> | | 3V
> 120 VAC --- --- to clock
> ^ _
> | |
> 10K | |
> -----------www---------------------------------->
>
> *Digikey's $29.95 M400-KIT-ND 400 V capacitor assortment contains
> 10 of these, along with 10 of 14 other values from 0.001 to 0.1 uF.

The rest of this stuff is cheap...

$13.65 for 100 1N5231BD1CTND 5.1V zeners,
$15.86 for 1000 P10KBACTND 10K resistors,
and a line cord cut off an old appliance.

Anyone else want to burn their house down? :-)

Nick

nicksanspam@ece.villanova.edu

2006-01-07, 5:21 am

nick pine <nicksanspam@early.com> wrote:

>
>The rest of this trickle charger is cheap...
>
>$13.65 for 100 1N5231BD1CTND 5.1V zeners,
>$15.86 for 1000 P10KBACTND 10K resistors,
>and a line cord cut off an old appliance.

My smoke detector draws 7 uA = 60x370C, which makes C = 315 puffs, eg 2
0.001 uF 400 V caps in series, Digikey's P1058-ND, $11.43/100. They also
sell 12 V zeners suitable for 9 V batteries, 1N5242BDICT-ND, $13.65/100.

Nick

Bill_M

2006-01-07, 8:21 am

<nicksanspam@ece.villanova.edu> wrote in message
news:dpnvit$ghv@acadia.ece.villanova.edu...
> nick pine <nicksanspam@early.com> wrote:
>
>
> My smoke detector draws 7 uA = 60x370C, which makes C = 315 puffs, eg 2
> 0.001 uF 400 V caps in series, Digikey's P1058-ND, $11.43/100. They also
> sell 12 V zeners suitable for 9 V batteries, 1N5242BDICT-ND, $13.65/100.
>
> Nick
>

Of course you don't have enough current for the audible device so your smoke
detector should sit quietly by while you toast!

nicksanspam@ece.villanova.edu

2006-01-07, 9:21 am

Bill_M <nospam@nospam.net> wrote:

0.001 0.001 uF @400 V*
|| || |
----||-----||--------------------->|------------>
|| || | | |
| | 9V
120 VAC --- --- to smoke detector
^ _
| |
10K | |
-----------www---------------------------------->

My smoke detector draws 7 uA = 60Hzx2xsqrt(2)x120VxC, which makes C = 344 pF,
eg 2 0.001 uF 400 V caps in series, Digikey's P1058-ND, $11.43/100. They also
sell 12 V zeners suitable for 9 V batteries, 1N5242BDICT-ND, $13.65/100.

>Of course you don't have enough current for the audible device so your smoke
>detector should sit quietly by while you toast!

No. That current would come from the 9 V trickle-charged battery.

We might replace it every 6 years or so, if the alarm
fails to shriek with the test button.

Nick

Don K

2006-01-07, 11:21 am

<meow2222@care2.com> wrote in message news:1136561796.152806.158980@z14g2000cwz.googlegroups.com...
> nicksanspam@ece.villanova.edu wrote:
[color=darkred]
>
> X rated capacitors use fusible coatings, so a short causes a burn out
> of the conductor around the short. The overall capacitance is not
> noticeably affectde, IOW its self healing.
>
>
>
> Very fine wire sounds like effective fusing to me.

You only need 20mA of AC current to cause ventricular fibrillation.
If the capacitor fails, someone could get killed touching whatever
your circuit connects to.

Don

meow2222@care2.com

2006-01-08, 4:21 am

nicksanspam@ece.villanova.edu wrote:

> My smoke detector draws 7 uA = 60x370C, which makes C = 315 puffs, eg 2
> 0.001 uF 400 V caps in series, Digikey's P1058-ND, $11.43/100. They also
> sell 12 V zeners suitable for 9 V batteries, 1N5242BDICT-ND, $13.65/100.
>
> Nick

You have to supply bleeping power, relying on the battery would be
unsatisfactory. In which case it'll draw bleeping power al the time,
but since its almost entirely capacitive, and a house's total load is
normally lagging, this will in fact reduce overall current consumption.
A tiny tiny bit.

NT

nicksanspam@ece.villanova.edu

2006-01-08, 5:21 am

0.0047 uF @400 V*
|| |
-----------||--------------------->|------------>
|| | | |
| | 1.5V
120 VAC --- --- to clock
^ _
| |
10K | |
-----------www---------------------------------->

can trickle-charge a Seth Thomas quartz clock with hands and a AA battery
("Replace every 12 months or in case of suddenly inaccurate timekeeping.")
The trickle-charged battery might last 10 years.

The battery current jumps when the second hand ticks, but a 1K resistor
and a 10K microfarad smoothing capacitor reveal an average 95 microamps
= 60Hzx2xsqrt(2)x120VxC, which makes C = 0.0047 uF, one of the 150 caps
in Digikey's $29.95 M400-KIT-ND. Their P10KBACT-ND 10K resistors cost
$15.86/1000... 1N5231BD1CTND 5.1V zener diodes cost $13.65/100. Their
number is 1-800-344-4539. Most orders are shipped in 12-14 minutes.

This circuit uses about 1.5Vx95uA = 142 microwatts, ie 1.2 Wh/year worth
$0.000125 at 10 cents/kWh. It's probably illegal. Don't try this at home.

Nick

nicksanspam@ece.villanova.edu

2006-01-08, 5:21 am

<meow2222@care2.com> wrote:
>
>
>You have to supply bleeping power, relying on the battery would be
>unsatisfactory. In which case it'll draw bleeping power al the time,

Only with constant house fires.

Nick

phatty mo

2006-01-08, 7:21 am

nicksanspam@ece.villanova.edu wrote:
> I finally got tired of replacing the 2 C-cells in a clock with a moving
> pendulum, so I measured the current (3 volts at 340 microamps) and built
> a charge pump like this, viewed in a fixed font:
>
> 0.047 uF @400 V
> || |
> -----------||--------------------->|------------>
> || | | |
> | | 3V
> 120 VAC --- --- to clock
> ^ _
> 0.047 uF @400 V | |
> || | |
> -----------||----------------------------------->
> ||
>
> I used two caps in case one shorts and for some ground isolation. The diodes
> are 5.1 V zeners ($1.29 for 2 at Radio Shack) to limit the clock voltage if
> someone unplugs the batteries. This circuit supplies 390 microamps. I hope
> to avoid replacing the batteries until their shelf life runs out in 2012 :-)
>
> This could be useful for lots of low-power stuff, eg smoke detectors.
>
> Nick
>

Why not a small dc-dc converter,from your main 12/24/48V battery bank..
Safer,and probably more efficient. (takes the inverter out of the
loop,atleast.)

nicksanspam@ece.villanova.edu

2006-01-08, 9:21 am

phatty mo <ptaylor@nospam.com> wrote:

>Why not a small dc-dc converter,from your main 12/24/48V battery bank..

I don't have a battery bank.

>Safer,and probably more efficient. (takes the inverter out of the
>loop,atleast.)

If your main inverter doesn't run 100% of the time, you might make the cap
larger to charge the battery more when the inverter does run. This circuit
itself is unlikely to make the inverter come out of hibernation.

Nick

SolarFlare

2006-01-08, 11:21 am

These "hot" circuits were always accompanied by safety
devices that disabled them from human contact.
eg.
- polarized plugs
- cheater cords that disconnected when the back was
removed
- all plastic insulated knobs to avoid metal exposure.

<nicksanspam@ece.villanova.edu> wrote in message
news:dpqioq$clg@acadia.ece.villanova.edu...
> 0.0047 uF @400 V*
> || |
> -----------||--------------------->|------------>
> || | | |
> | | 1.5V
> 120 VAC --- --- to
clock
> ^ _
> | |
> 10K | |
> -----------www---------------------------------->
>
> can trickle-charge a Seth Thomas quartz clock with
hands and a AA battery
> ("Replace every 12 months or in case of suddenly
inaccurate timekeeping.")
> The trickle-charged battery might last 10 years.
>
> The battery current jumps when the second hand ticks,
but a 1K resistor
> and a 10K microfarad smoothing capacitor reveal an
average 95 microamps
> = 60Hzx2xsqrt(2)x120VxC, which makes C = 0.0047 uF,
one of the 150 caps
> in Digikey's $29.95 M400-KIT-ND. Their P10KBACT-ND
10K resistors cost
> $15.86/1000... 1N5231BD1CTND 5.1V zener diodes cost
$13.65/100. Their
> number is 1-800-344-4539. Most orders are shipped in
12-14 minutes.
>
> This circuit uses about 1.5Vx95uA = 142 microwatts,
ie 1.2 Wh/year worth
> $0.000125 at 10 cents/kWh. It's probably illegal.
Don't try this at home.
>
> Nick
>

SolarFlare

2006-01-08, 11:21 am

fuck. get a small flexible PV panel and use the damn
thing.

<nicksanspam@ece.villanova.edu> wrote in message
news:dpr0m6$qlc@acadia.ece.villanova.edu...
> phatty mo <ptaylor@nospam.com> wrote:
>
12/24/48V battery bank..[color=darkred]
>
> I don't have a battery bank.
>
inverter out of the[color=darkred]
>
> If your main inverter doesn't run 100% of the time,
you might make the cap
> larger to charge the battery more when the inverter
does run. This circuit
> itself is unlikely to make the inverter come out of
hibernation.
>
> Nick
>

larry

2006-01-08, 1:21 pm

SolarFlare wrote:
>get a small flexible PV panel
>
glue it to the face of the clock
add a series resistor and schottky diode to charge the
battery.

the frugal will steal the parts from a defunct solar
calculator ;-)

Nick, put equal value cap and resistor in series with each
line and your diodes in a small box with ac plug (gutted
wall wart- there's justice?) then run small cable (like the
old earphone cable) up to clock. Paint red insulator over
any "hot" parts in clock. The "power" cable will be about
as dangerous as any current small appliance "leakage" since
most have .045 mF caps from EACH power lead to chassis. UL
specifies an allowable leakage level. 5 ma sounds familiar
since that's the level that GFI's are supposed to trip at.

There's a thought, wire it any way you want to, then plug it
into a gfi ;-) hook all your clocks, smoke detectors, etc
together and use just one gfi. the gfi will use more power
than you're saving.

have a good new year -larry / dallas

SolarFlaire

2006-01-08, 2:21 pm

Get an old coil for induction and put a series diode to
the battery. Hang it someplace over wiring with a good
load feed.

voila...self contained clock with no dangerous
connection to high voltage.

"larry" <noone@home.com> wrote in message
news:lpbwf.45495$dO2.2278@newssvr29.news.prodigy.net...
> SolarFlare wrote:
> glue it to the face of the clock
> add a series resistor and schottky diode to charge
the
> battery.
>
> the frugal will steal the parts from a defunct solar
> calculator ;-)
>
> Nick, put equal value cap and resistor in series with
each
> line and your diodes in a small box with ac plug
(gutted
> wall wart- there's justice?) then run small cable
(like the
> old earphone cable) up to clock. Paint red insulator
over
> any "hot" parts in clock. The "power" cable will be
about
> as dangerous as any current small appliance "leakage"
since
> most have .045 mF caps from EACH power lead to
chassis. UL
> specifies an allowable leakage level. 5 ma sounds
familiar
> since that's the level that GFI's are supposed to
trip at.
>
> There's a thought, wire it any way you want to, then
plug it
> into a gfi ;-) hook all your clocks, smoke
detectors, etc
> together and use just one gfi. the gfi will use more
power
> than you're saving.
>
> have a good new year -larry / dallas

meow2222@care2.com

2006-01-09, 4:21 am

nicksanspam@ece.villanova.edu wrote:
> Bill_M <nospam@nospam.net> wrote:

>
> No. That current would come from the 9 V trickle-charged battery.
>
> We might replace it every 6 years or so, if the alarm
> fails to shriek with the test button.
>
> Nick

But youve then got a battery alarm, not a mains/battery one. Whats the
point of running a mains supply to it if it wont work off the mains
supply.

I always wondered about using miniature audio transformers for mini
psus, get it ringing at eg 500Hz with a series cap. Wont have enough
insulation to be touch safe though. But maybe custom tfs could work.
But not worth it, as the bigger 50Hz transformer would be cheaper than
the cap.

NT

meow2222@care2.com

2006-01-09, 5:21 am

Don K wrote:
> <meow2222@care2.com> wrote in message news:1136561796.152806.158980@z14g2000cwz.googlegroups.com...
[color=darkred]
>
>
> You only need 20mA of AC current to cause ventricular fibrillation.
> If the capacitor fails, someone could get killed touching whatever
> your circuit connects to.
>
> Don

It would be a foolish designer that enabled users to touch the output
of one of these, so thats a non issue in a competent design. If for
some reason they did, Y rated caps would be more appropriate than X -
but still, liability like that isnt something I'd want to take on
unnecessarily.

As far as fusing, if a cap shorts, enough i will flow to pop a fine
wire, assuming it really is fine. A single strand of a thin stranded
equipment wire etc. So the fuse concept is good.

I suppose if one wanted to improve the safety of an unsafe device (ie
nonisolated supply with outputs touchable) one could put a cap in both
poles and earth the supply output. Would need to ensure R is
significant to avoid RCD problems.

Note this would work as a 1 cap supply, as the E connection would
effectively short out the neutral capacitor. Ick.

NT

meow2222@care2.com

2006-01-09, 5:21 am

Stretch

2006-01-09, 5:21 am

Nick,
All the parts should be in the HOT side for safety. Move thre resistor
from the bottom leg(neutral) to the top (hot) leg. Make the resistor
bigger. Safer would be to use a small transformer to step the voltage
down, then just put a diode in the secondary. That is what most large
manufacturers who don't want to get sued do these days.

Stretch

meow2222@care2.com

2006-01-09, 5:21 am

nicksanspam@ece.villanova.edu wrote:
> <meow2222@care2.com> wrote:
>
> Only with constant house fires.
>
> Nick

witty, but missing the point. Think about reliability and redundancy,
how very little you'd save by not using a transformer, the cost of
routing mains to the alarm, and consider the significant loss in
utility of a system that will fail if battery OR mains power supply
fails versus a system that will only fail if battery AND mains power
supply fail.

So yes, to be worth doing it will need to draw bleep power
continuously. It wont add to the bill or the current consumption, as
whole house loads are normally lagging.

NT

nicksanspam@ece.villanova.edu

2006-01-09, 8:21 am

Stretch <sixfoot7@sccoast.net> wrote:

>All the parts should be in the HOT side for safety. Move thre resistor
>from the bottom leg(neutral) to the top (hot) leg.

The first old line cord I used was unpolarized...

>Make the resistor bigger.

That eats into efficiency, and it might need to change with
the required current. Right now, only the cap needs to change.

>Safer would be to use a small transformer to step the voltage down,
>then just put a diode in the secondary.

Exactly what I want to avoid, with a thousand times the power consumption :-)

Nick

SolarFlaire

2006-01-09, 10:21 pm

Nick wants to correct the power factor for the rest of
the house while he is at it...LOL

<nicksanspam@ece.villanova.edu> wrote in message
news:dpthi8$k8o@acadia.ece.villanova.edu...
> Stretch <sixfoot7@sccoast.net> wrote:
>
Move thre resistor[color=darkred]
>
> The first old line cord I used was unpolarized...
>
>
> That eats into efficiency, and it might need to
change with
> the required current. Right now, only the cap needs
to change.
>
the voltage down,[color=darkred]
>
> Exactly what I want to avoid, with a thousand times
the power consumption :-)
>
> Nick
>

George Ghio

2006-01-10, 4:21 am

nicksanspam@ece.villanova.edu wrote:
> Stretch <sixfoot7@sccoast.net> wrote:
>
>
>
>
> The first old line cord I used was unpolarized...
>
>
>
>
> That eats into efficiency, and it might need to change with
> the required current. Right now, only the cap needs to change.
>
>
>
>
> Exactly what I want to avoid, with a thousand times the power consumption :-)
>
> Nick
>

What we have is a battery powered electric Grandfather clock. That's
stupid enough on it's own. Still, it's too hard to wind up a real
Grandfather clock once a week.

But then Nick in his infinite silliness got tired of replacing the
batteries every year. How tedious it must have been.

Is Nick lazy or just sad?

Stretch

2006-01-10, 8:21 am

Nick just likes to reinvent the wheel, whilr ignoring all advances is
safety made along the way. When we are dealing with milliamps or
microamps in the charging circuit, efficiency hardly seems an issue.
Now on a battery only system, efficiency has an effect on battery
life.

He is using a non-rechargible battery that will be ruined by his
recharging scheme. At these current levels, it won't blow up or catch
fire, it just won't work when he needs it. It is a goofy thing to do
for a once a yerar or twice a year battery change.

Strange way to gain efficiency. Reinventing what has already been
invented is rarely cost effective. You can buy something off the shelf
that works for less than you can cobble together some kludge that will
not work reliably. And for a smoke detector, reliability is
EVERYTHING!!!

Now he will have to respond to this. Probably will dig up something
out of NREL :-)

Stretch

Stretch

meow2222@care2.com

2006-01-10, 12:21 pm

George Ghio wrote:
> nicksanspam@ece.villanova.edu wrote:
>
> What we have is a battery powered electric Grandfather clock. That's
> stupid enough on it's own. Still, it's too hard to wind up a real
> Grandfather clock once a week.
>
> But then Nick in his infinite silliness got tired of replacing the
> batteries every year. How tedious it must have been.
>
> Is Nick lazy or just sad?

Dead batteries in smoke detectors are one of the big causes of death in
house fires.

No, the batteries dont jump out and get ya, they just fail to tell you
to get out in time.

NT

meow2222@care2.com

2006-01-10, 12:21 pm

Stretch wrote:

> Nick just likes to reinvent the wheel, whilr ignoring all advances is
> safety made along the way.

How is describing an old CR psu reinventing anything?

> When we are dealing with milliamps or
> microamps in the charging circuit, efficiency hardly seems an issue.

We know that isnt so. All those household appliances on standby drawing
milliamps nedes a whole power generating station to supply.
The CR supply uses less money and materials in construction too. In
this case it also saves battery replacements
- more material and energy waste
- lives saved as a result of the battery still being available to work

> Now on a battery only system, efficiency has an effect on battery
> life.
>
> He is using a non-rechargible battery that will be ruined by his
> recharging scheme. At these current levels, it won't blow up or catch
> fire, it just won't work when he needs it.

I wasnt aware that microamp charging would damage non rc cells. Is this
true, can you offer a reference?

> It is a goofy thing to do
> for a once a yerar or twice a year battery change.

whats goofy about saving lives?

> Strange way to gain efficiency.

in what way is it strange?

> Reinventing what has already been
> invented is rarely cost effective.

there is no reinvention here

> You can buy something off the shelf
> that works for less than you can cobble together some kludge that will
> not work reliably.

not so. Go ahead and give us a link to one thats cheaper than this.

> And for a smoke detector, reliability is
> EVERYTHING!!!

Yes, and my one complaint about Nicks application sits here. If either
mains or battery fails, his detector wont sound. Imho if youre going to
the trouble of running mains to the detector it makes more sense to pay
the small extra and ensure it will sound if either mains or battery is
alive.

That issue can be solved simply by making the CR pass enough i to power
the alarm during sounding.

NT

nicksanspam@ece.villanova.edu

2006-01-10, 2:21 pm

<meow2222@care2.com> wrote:

>... If either mains or battery fails, his detector wont sound.

It will sound, if "the mains fail" for less than 1 year :-)

>... if youre going to the trouble of running mains to the detector

That's just a line cord cut off a dead appliance, in many cases.

Nick

SolarFlaire

2006-01-10, 7:21 pm

Won't fly in Canada. Smokes have to be on their own
circuit.

<nicksanspam@ece.villanova.edu> wrote in message
news:dq0ths$cd9@acadia.ece.villanova.edu...
> <meow2222@care2.com> wrote:
>
wont sound.[color=darkred]
>
> It will sound, if "the mains fail" for less than 1
year :-)
>
to the detector[color=darkred]
>
> That's just a line cord cut off a dead appliance, in
many cases.
>
> Nick
>

nicksanspam@ece.villanova.edu

2006-01-10, 9:21 pm

SolarFlaire <sf@hot.mail.invalid> wrote:

>Won't fly in Canada. Smokes have to be on their own circuit.

You may find that is untrue, if the AC merely keeps the battery charged.

Nick

SolarFlaire

2006-01-11, 12:21 am

Smokes have to be on their own circuit. Battery
operated ones do not pass code.

<nicksanspam@ece.villanova.edu> wrote in message
news:dq1io3$4t3@acadia.ece.villanova.edu...
> SolarFlaire <sf@hot.mail.invalid> wrote:
>
circuit.[color=darkred]
>
> You may find that is untrue, if the AC merely keeps
the battery charged.
>
> Nick
>

meow2222@care2.com

2006-01-11, 12:21 pm

nicksanspam@ece.villanova.edu wrote:
> <meow2222@care2.com> wrote:
>
>
> It will sound, if "the mains fail" for less than 1 year :-)

If mains is lost, and battery works, youre right it will sound.
If the battery goes down it wont. So you dont get the full reliability
benefit of a mains alarm with battery backup.

>
> That's just a line cord cut off a dead appliance, in many cases.

well, not here. One needs to use 1mm2 3 core cable, and route and wire
it in. Which is a good deal more than just grabbing a bit of flex. You
may be happy to string a bit of fle across the ceiling, but youre in a
minority on that.

NT

nicksanspam@ece.villanova.edu

2006-01-11, 7:21 pm

SolarFlaire <sf@hot.mail.invalid> wrote:

>Won't fly in Canada. Smokes have to be on their own circuit.

Are you sure? :-)

http://www.safety-council.org/info/home/smalarm.htm

.... Smoke alarms can be electrically powered, battery powered,
or a combination of both.

http://www.ibc.ca/homeauto_homeinsure_smokealarm.asp

.... You should also test your alarm monthly to make sure it's working. Use
a candle, cigarette, or incense to introduce smoke into the alarm until it
sounds. If the alarm is battery-powered and doesn't sound, replace the
battery and try again. If it's electrically-operated and doesn't sound,
check the fuse and try again. In either case, if the alarm still isn't
working, replace the unit. A dead unit is worse than none at all, as
it can give you a false sense of security.

Saanich BC Smoke Alarm Bylaw No. 7126:

.... Smoke alarms installed pursuant to this bylaw may be battery powered
or connected to an electrical circuit... Where the owner installs an
individually battery powered smoke alarm, the owner shall install new
batteries in the alarm at least once every twelve months.

And finally, your Queen :-)

http://www.hc-sc.gc.ca/iyh-vsv/prod/detect_e.html

Smoke Detectors

(c) Her Majesty the Queen in Right of Canada,
represented by the Minister of Health, 2004

.... Change the batteries as often as recommended by the manufacturer.

Nick

Bob Ward

2006-01-11, 10:21 pm

On 11 Jan 2006 17:11:32 -0500, nicksanspam@ece.villanova.edu wrote:

>SolarFlaire <sf@hot.mail.invalid> wrote:
>
>
>Are you sure? :-)
>
>http://www.safety-council.org/info/home/smalarm.htm
>
>... Smoke alarms can be electrically powered, battery powered,
>or a combination of both.
>
>http://www.ibc.ca/homeauto_homeinsure_smokealarm.asp
>
>... You should also test your alarm monthly to make sure it's working. Use
>a candle, cigarette, or incense to introduce smoke into the alarm until it
>sounds. If the alarm is battery-powered and doesn't sound, replace the
>battery and try again. If it's electrically-operated and doesn't sound,
>check the fuse and try again. In either case, if the alarm still isn't
>working, replace the unit. A dead unit is worse than none at all, as
>it can give you a false sense of security.
>
>Saanich BC Smoke Alarm Bylaw No. 7126:
>
>... Smoke alarms installed pursuant to this bylaw may be battery powered
>or connected to an electrical circuit... Where the owner installs an
>individually battery powered smoke alarm, the owner shall install new
>batteries in the alarm at least once every twelve months.
>
>And finally, your Queen :-)
>
>http://www.hc-sc.gc.ca/iyh-vsv/prod/detect_e.html
>
>Smoke Detectors
>
>(c) Her Majesty the Queen in Right of Canada,
>represented by the Minister of Health, 2004
>
>... Change the batteries as often as recommended by the manufacturer.
>
>Nick

Nothing I see there refutes the statement that smoke alarms must be on
their own circuit... that is, they can't legally be plugged into a
random outlet...

SolarFlaire

2006-01-11, 11:21 pm

No.I am not sure now....LOL After some research all I
can find is in the building code but the 1990
Electrical Code says it' OK to combine smoke alarms on
circuits with other devices.

I don't believe battery units are allowed in new
construction at all because nobdy ever checks them.
They must be wired in.

From our latest Building code:

A-3.2.4.21.(5) Smoke Alarm Installation.
The Electrical Code permits a smoke alarm to be
installed on most residential circuits that carry
lighting outlets and receptacles. It is the intent of
this Code that any other item on a circuit with a smoke
alarm should be unlikely to be overloaded and trip the
breaker with a resultant loss of power that is not
sufficiently annoying for the breaker to be restored to
the on position. It is considered that an interior
bathroom light or a kitchen light fulfills this intent,
but that circuits restricted to receptacles do not
fulfill this intent.

Not quite what I was thinking but thanx for the red
flag.

<nicksanspam@ece.villanova.edu> wrote in message
news:dq3vqk$ohq@acadia.ece.villanova.edu...
> SolarFlaire <sf@hot.mail.invalid> wrote:
>
circuit.[color=darkred]
>
> Are you sure? :-)
>
> http://www.safety-council.org/info/home/smalarm.htm
>
> ... Smoke alarms can be electrically powered, battery
powered,
> or a combination of both.
>
> http://www.ibc.ca/homeauto_homeinsure_smokealarm.asp
>
> ... You should also test your alarm monthly to make
sure it's working. Use
> a candle, cigarette, or incense to introduce smoke
into the alarm until it
> sounds. If the alarm is battery-powered and doesn't
sound, replace the
> battery and try again. If it's electrically-operated
and doesn't sound,
> check the fuse and try again. In either case, if the
alarm still isn't
> working, replace the unit. A dead unit is worse than
none at all, as
> it can give you a false sense of security.
>
> Saanich BC Smoke Alarm Bylaw No. 7126:
>
> ... Smoke alarms installed pursuant to this bylaw may
be battery powered
> or connected to an electrical circuit... Where the
owner installs an
> individually battery powered smoke alarm, the owner
shall install new
> batteries in the alarm at least once every twelve
months.
>
> And finally, your Queen :-)
>
> http://www.hc-sc.gc.ca/iyh-vsv/prod/detect_e.html
>
> Smoke Detectors
>
> (c) Her Majesty the Queen in Right of Canada,
> represented by the Minister of Health, 2004
>
> ... Change the batteries as often as recommended by
the manufacturer.
>
> Nick
>

SolarFlaire

2006-01-11, 11:21 pm

Have you ever disconnected a smoke detector from the
mains supply?

I have

Those bastards wail for 20 minutes after
disconnection. They are a pain in the butt. I do not
understand where they store all that energy after 15
years of usage.

<meow2222@care2.com> wrote in message
news:1136993310.364340.39460@g14g2000cwa.googlegroups.com...
> nicksanspam@ece.villanova.edu wrote:
wont sound.[color=darkred]
year :-)[color=darkred]
>
> If mains is lost, and battery works, youre right it
will sound.
> If the battery goes down it wont. So you dont get the
full reliability
> benefit of a mains alarm with battery backup.
>
>
to the detector[color=darkred]
in many cases.[color=darkred]
>
> well, not here. One needs to use 1mm2 3 core cable,
and route and wire
> it in. Which is a good deal more than just grabbing a
bit of flex. You
> may be happy to string a bit of fle across the
ceiling, but youre in a
> minority on that.
>
>
> NT
>

nicksanspam@ece.villanova.edu

2006-01-12, 3:21 am

SolarFlaire <sf@hot.mail.invalid> wrote:

>I don't believe battery units are allowed in new construction
>at all because nobdy ever checks them. They must be wired in.

Alarms that beep when the battery is low are self-checking, if
anyone's home and they beep long enough and the occupants don't
simply remove the battery to stop the noise, which I seem to have
done with my smoke detector a year ago. I just opened it up to
check the battery current and... whoa, no battery! :-)

The Canadian UL standard for smoke alarms (ULC S541?) seems to allow
a battery with AC backup. (I haven't seen the standard itself, just
a summary of it.)

>From our latest Building code:
>
>A-3.2.4.21.(5) Smoke Alarm Installation.
>The Electrical Code permits a smoke alarm to be
>installed on most residential circuits that carry
>lighting outlets and receptacles. It is the intent of
>this Code that any other item on a circuit with a smoke
>alarm should be unlikely to be overloaded and trip the
>breaker with a resultant loss of power that is not
>sufficiently annoying for the breaker to be restored to
>the on position. It is considered that an interior
>bathroom light or a kitchen light fulfills this intent,
>but that circuits restricted to receptacles do not
>fulfill this intent.

This makes a smoke alarm power failure more apparent than if it were on
a dedicated circuit. Failure alarms are good. High availability can come
with long-life redundant components AND a way to tell if one has failed
so we can repair it before others are likely to fail, keeping the system
in working condition during the repair period.

We might compare numerical UNavailabilities in seconds per year for

1. AC only (600?)
2. Battery only (10?),
3. Battery with AC backup (alarm only works if battery works) (2?), and
4. Alarm works if either AC or battery works (1?).

The AC only option may not be as good as it seems based on grid failure
stats, since a house fire can cause a loss of house power.

Nick

nicksanspam@ece.villanova.edu

2006-01-13, 11:21 am

Rich Komp replies:

Nick,
You are right. I have used non-rechargable batteries for years with
solar battery chargers. The current is controlled by the number of
photons going into the PV cells, not the internal resistance of the
batteries. I once deliberately grossly overcharged a regular alkaline
battery in a solar charger and got it to explode like a firecracker, but
it took almost an amp for a single AA cell, not the microamps we are
discussing. I will admit that after 5 years or so in a solar clock, some
of the batteries have leaked, but the battery contacts, weren't too hard
to clean (and I've never seen a fire from this).
I like breaking rules, especially when they are so FORCEFUL.
Rich

> <hallerb@aol.com> wrote:
>
>
> NO!
>
> fire!
>
> How much will they overheat if overchaged at 3Vx50uA = 150
> microwatts? :-)
>
>
> NO!
>
> Happy new year,

Nick

daestrom

2006-01-14, 10:21 am

<nicksanspam@ece.villanova.edu> wrote in message
news:dq4sb1$o3g@acadia.ece.villanova.edu...
> SolarFlaire <sf@hot.mail.invalid> wrote:
>
>
> Alarms that beep when the battery is low are self-checking, if
> anyone's home and they beep long enough and the occupants don't
> simply remove the battery to stop the noise, which I seem to have
> done with my smoke detector a year ago. I just opened it up to
> check the battery current and... whoa, no battery! :-)
>

The schools around here have a fire safety program for the kids every
October. So I got in the habit over the years of buying nine new 9V
batteries each October and changing the batteries in the smoke detectors
(yes, *9* of them).

Just put it on your calender to do this during some season (say superbowl,
or halloween, or new-years) and just do it. The batteries I take out still
have plenty of life, so I use them for other things. But the smoke
detectors is one place I don't skimp.

daestrom

nicksanspam@ece.villanova.edu

2006-01-14, 6:21 pm

daestrom <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote:

>... I got in the habit over the years of buying nine new 9V batteries each
>October and changing the batteries in the smoke detectors (yes, *9* of them).

A bad habit? :-)

>Just put it on your calender to do this during some season (say superbowl,
>or halloween, or new-years) and just do it. The batteries I take out still
>have plenty of life, so I use them for other things. But the smoke
>detectors is one place I don't skimp.

You might charge-pump them and merely test yearly by pushing the button...

My clock radio has 3 AAA cells and uses 120 uA for the clock alone, 25 mA
with low radio volume, and 50 mA at high volume. At low-volume for 1 hour
per day, it needs an average (23hx120ua+1hx25mA)/24h = 1.16 mA = 60x370C,
which makes C = 0.052 uF... 0.1 can float the batteries at about 4.5 V
without overcharging, like this, viewed in a fixed font like Courier:

0.1 uF @400 V*
|| 0.6V
-----------||--------------------->|------------>
|| | |
| | 4.5V
120 VAC /-/ --- to radio
^ 5.1V _
| |
10K | |
-----------www---------------------------------->

This can go into the wall-wart that came with the radio, with
a wire inside the radio to connect its jack to the batteries.

A similar circuit might keep our church clocks running with power from
the seldom-lit exit signs below them. They have a single AA cell.

0.1 uF @400 V* --1.8V--
||
-----------||------------------>|->|->|--------->
|| | |
| | 1.5V
120 VAC /-/ --- to clock
^ 3.3V _
| |
10K | |
-----------www---------------------------------->

Digikey's 1N5226BDITR-ND 3.3 V zeners cost $13.65/100,
Their 586-1361-1-ND switching diodes cost $3.38/100.

Nick

daestrom

2006-01-15, 10:21 am

<nicksanspam@ece.villanova.edu> wrote in message
news:dqbrcg$fmh@acadia.ece.villanova.edu...
> daestrom <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote:
>
>
> A bad habit? :-)
>
>
> You might charge-pump them and merely test yearly by pushing the button...
>

No, I test them monthly, and replace the battery yearly regardless of their
state of charge. The batteries get used in other things, but smoke
detectors and CO monitors are not the sort of applications I 'experiment'
with.

daestrom

nicksanspam@ece.villanova.edu

2006-01-15, 6:21 pm

daestrom <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote:

[color=darkred]
>... I test them monthly, and replace the battery yearly regardless of their
>state of charge.

If you and your family are worth $10 million and non-pumped batteries have
a 2 year MTTF and pumped batteries have a 10 year MTTF, with a 2 week MTTR
for both, (because it takes a month to discover them) and you have a fire
every 10 years, does your battery changing save money, on average?

Nick

Anthony Matonak

2006-01-16, 3:21 am

nicksanspam@ece.villanova.edu wrote:
....
> If you and your family are worth $10 million and non-pumped batteries have
> a 2 year MTTF and pumped batteries have a 10 year MTTF, with a 2 week MTTR
> for both, (because it takes a month to discover them) and you have a fire
> every 10 years, does your battery changing save money, on average?

Nick, you've totally lost me on this one. First off, people aren't worth
$10 million. The average cost to an insurer for someones death is in
the $50,000 range and certainly children wouldn't be valued as much. Ask
any life insurance salesman what kind of policy they would sell for a
child. I doubt they would sell many over $10,000. Houses cost more than
people today. Replacing a home in Los Angeles could easily cost half a
million or more.

Next, I don't understand anything about this MTTF you're tossing around.
Replacing the batteries within one year is a safety measure, as is the
replacement of the alarms themselves every 10 years. You can run all the
theoretical analysis you want on projected failure rates but it's always
better to error on the side of caution. I'd rather spend the extra $10
a year on batteries if it means I don't die. It would be a cheap and
stupid thing to die because I wanted to save a couple of bucks.

Anthony

Sambo

2006-01-16, 4:21 am

Anthony Matonak <anthonym40@nothing.like.comcast.net> wrote:
> nicksanspam@ece.villanova.edu wrote:
> ...
[color=darkred]
> Nick, you've totally lost me on this one.

It was a joke, joyce.

> First off, people aren't
> worth $10 million. The average cost to an insurer for someones death
> is in the $50,000 range and certainly children wouldn't be valued as
> much. Ask any life insurance salesman what kind of policy they would
> sell for a child. I doubt they would sell many over $10,000. Houses
> cost more than people today. Replacing a home in Los Angeles could
> easily cost half a million or more.
>
> Next, I don't understand anything about this MTTF you're tossing
> around. Replacing the batteries within one year is a safety measure,
> as is the replacement of the alarms themselves every 10 years. You
> can run all the theoretical analysis you want on projected failure
> rates but it's always better to error on the side of caution. I'd
> rather spend the extra $10 a year on batteries if it means I don't
> die. It would be a cheap and stupid thing to die because I wanted to
> save a couple of bucks.
> Anthony

nicksanspam@ece.villanova.edu

2006-01-16, 7:21 am

Anthony Matonak <anthonym40@nothing.like.comcast.net> wrote:

>nicksanspam@ece.villanova.edu wrote:
>...

The answer to that question is no, if the pumped batteries have a higher
MTTF, which seems reasonable to me, but you might imagine otherwise...
[color=darkred]
>Nick, you've totally lost me on this one. First off, people aren't worth
>$10 million. The average cost to an insurer for someones death is in
>the $50,000 range and certainly children wouldn't be valued as much. Ask
>any life insurance salesman what kind of policy they would sell for a
>child. I doubt they would sell many over $10,000. Houses cost more than
>people today. Replacing a home in Los Angeles could easily cost half a
>million or more.

That's part of the picture. People can be worth a lot more than they are
typically insured for, if someone with deep pockets is paying. If daestrom
were a promising young brain surgeon, we might estimate he would earn
$10 million or more over the remainder of his lifetime... $50K/year over
50 years is $2.5 million.

>Next, I don't understand anything about this MTTF you're tossing around.
>Replacing the batteries within one year is a safety measure, as is the
>replacement of the alarms themselves every 10 years. You can run all the
>theoretical analysis you want on projected failure rates but it's always
>better to error on the side of caution. I'd rather spend the extra $10
>a year on batteries if it means I don't die. It would be a cheap and
>stupid thing to die because I wanted to save a couple of bucks.

It's more complex, no? For instance, replacing batteries takes time, and you
might subtract that time from your lifetime, unless you love that activity,
and you might fall off a ladder when replacing a battery or drive into a tree
on the way to the battery store, and you might use the money you save by less
frequent replacements to armor-plate your SUV or buy safer tires or upgrade
the seatbelts, which might be better safety investments.

Nick

William P.N. Smith

2006-01-16, 9:21 am

Anthony Matonak <anthonym40@nothing.like.comcast.net> wrote:
>The average cost to an insurer for someones death is in
>the $50,000 range and certainly children wouldn't be valued as much. Ask
>any life insurance salesman what kind of policy they would sell for a
>child. I doubt they would sell many over $10,000.

Not to pick nits, but you can buy life insurance for any amount you
want, as long as you are willing to pay the premiums. Heck, Lloyds
will {insure,make book on} any person, thing, or happenstance at any
value you want to pay for.

Or do you mean either:

An insurance claim against a homeowner where something about the
property resulted in the death of an otherwise uninsured person (a
homeowner's liability policy, not a life insurance policy)?

Or

Insurance salesmen don't sell many policies for children or many
policies for more than $50K?

daestrom

2006-01-16, 9:21 pm

"Anthony Matonak" <anthonym40@nothing.like.comcast.net> wrote in message
news:I9GdnZ2IvcsJplbeRVn-gQ@comcast.com...
> nicksanspam@ece.villanova.edu wrote:
> ...
>
> Nick, you've totally lost me on this one. First off, people aren't worth
> $10 million. The average cost to an insurer for someones death is in
> the $50,000 range and certainly children wouldn't be valued as much. Ask
> any life insurance salesman what kind of policy they would sell for a
> child. I doubt they would sell many over $10,000.

Some insurance salespersons will sell you as large a policy as you want,
regardless of the logic involved :-( The only difference is the premium you
pay.

But an insured policy value is *not* the measure of human life. Especially
a close family member. Also, the *costs* of replacing a house go way beyond
the $ value.

Smoke detectors, portable fire extinguishers, CO monitors are all just
safety devices designed (usually) to help protect one from various hazards.

Replacing batteries in them on a regular basis is similar to fastening your
seatbelt or storing gasoline in approved containers or turning off the power
before rewiring a wall switch, or.... Sure you can 'get away' with skimping
on these sorts of things. There's a simple name for folks that willingly
chose to not follow well-founded safety precautions: 'statistic'.

daestrom

meow2222@care2.com

2006-01-16, 9:21 pm

nicksanspam@ece.villanova.edu wrote:

> If you and your family are worth $10 million and non-pumped batteries have
> a 2 year MTTF and pumped batteries have a 10 year MTTF, with a 2 week MTTR
> for both, (because it takes a month to discover them) and you have a fire
> every 10 years, does your battery changing save money, on average?
>
> Nick

Now we get to see the results of talking engineeering to people that
dont understand it.

NT

George Ghio

2006-01-17, 2:21 am

Life insurance - Placing a bet on your life, if you die you win.

Anthony Matonak wrote:
> nicksanspam@ece.villanova.edu wrote:
> ...
>
>
>
> Nick, you've totally lost me on this one. First off, people aren't worth
> $10 million. The average cost to an insurer for someones death is in
> the $50,000 range and certainly children wouldn't be valued as much. Ask
> any life insurance salesman what kind of policy they would sell for a
> child. I doubt they would sell many over $10,000. Houses cost more than
> people today. Replacing a home in Los Angeles could easily cost half a
> million or more.
>
> Next, I don't understand anything about this MTTF you're tossing around.
> Replacing the batteries within one year is a safety measure, as is the
> replacement of the alarms themselves every 10 years. You can run all the
> theoretical analysis you want on projected failure rates but it's always
> better to error on the side of caution. I'd rather spend the extra $10
> a year on batteries if it means I don't die. It would be a cheap and
> stupid thing to die because I wanted to save a couple of bucks.
>
> Anthony

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