sci.electronics.repair - 20 new messages in 9 topics - digest

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sci.electronics.repair
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sci.electronics.repair@googlegroups.com

Today's topics:

==============================================================================
TOPIC: Winter Special Electric Room Heater - Buy 1 Get 1 Free + Stylish
Branded Watch
http://groups.google.com/group/sci.electronics.repair/t/108bb21fe8393503?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Nov 24 2011 11:59 pm
From: ritesh

The product is Winter Special Electric Room Heater - Buy 1 Get 1 Free
http://www.naaptol.com/price/939934-Winter-Special-Electric-Room-Heater---Buy-1-Get-1-Free-+-Stylish-Branded-Watch.html.
This one is easy & safe to use also portable & light weighted with
power indicator light. With this enjoy heat & cold in the room. It is
a vertical type fan heater with OFF/ FAN/Hot I/Hot II wind. Also has
Cool Airflow for Summer Use. It has automatic control temperature for
overheat protection. It is Portable & Light Weight and is a Vertical
type fan heater. It comes in as Year End Dhamaka Offer. As one can
Shop & Win Cash Value Back Voucher Up to Rs. 1 Lakh.

==============================================================================
TOPIC: Repaired Harbor Freight digital caliper
http://groups.google.com/group/sci.electronics.repair/t/d8587e526bcdbeaf?hl=en
==============================================================================

== 1 of 5 ==
Date: Fri, Nov 25 2011 1:27 am
From: Gunner Asch

On Thu, 24 Nov 2011 22:29:50 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Thu, 24 Nov 2011 21:46:48 -0800, Jeff Liebermann <jeffl@cruzio.com>
>wrote:
>
>>>> The next question is for how long will it run? Assuming the calipers
>>>> can handle 3.0VDC without damage, how long will a junk 100UF
>>>> electrolytic cap run the calipers?
>>>
>>>a) How long will it run? Not nearly long enough, and b) 3.0VDC is
>>>waayyy too risky for my blood. 20uA will discharge 100uF from 2.0V to
>>>1.35V in 3.25 seconds.
>
>Trying the same calc using the super-cap formula from Pg 6 of:
><http://www.cde.com/catalogs/EDL.pdf>
>
> t = C delta V / I
> t = C[V0-(i*R)-V1] / (i+iL)
>where:
> t: Back-up time (sec)
> C: Capacitance of Type EDL (Farads)
> V0: Applied voltage (Volts)
> V1: Cut-off voltage (Volts)
> i: Current during back-up (Amps)
> iL: Leakage current (Amps)
> R: Internal resistance (ohms) at 1 kHz
>
>For this example, I'll use a 0.1F (type F) 5.5V 100 ohm cap.
>The low end of the tolerance range might drop this to 0.08F.
>V0 = 2.0V, V1 = 1.4V, i = 15uA, iL = 2uA
>
>Plugging in:
> t = C[V0-(i*R)-V1] / (i+iL)
> t = 0.08F[2.0V-(15uA*100ohms)-1.4V]/(15uA+2uA)
> t = 2800 sec = 47 minutes.
>Not bad.
>
>I guess the protective case that most calipers use will need a clear
>plastic window to keep it charged. Maybe another window on top of my
>toolbox.

http://www.judgetool.com/500seriessupercaliper-solarpoweredip67.aspx

http://www.widgetsupply.com/page/WS/PROD/caliper-digital/BAP30
(only 2 digits)

http://www.alibaba.com/showroom/solar-power-digital-caliper.html

Quite a number of them.....

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch

== 2 of 5 ==
Date: Fri, Nov 25 2011 7:06 am
From: dagmargoodboat@yahoo.com

On Nov 25, 12:46 am, Jeff Liebermann <je...@cruzio.com> wrote:
> On Thu, 24 Nov 2011 18:13:15 -0800 (PST), dagmargoodb...@yahoo.com
> wrote:
>
> I found this, which calculates and measures caliper battery life:
> <http://www.davehylands.com/Machinist/Caliper-Batteries/>

Yes, good site. I linked to it earlier in this thread.

> >Small, cheap and simple are the main factors here. The r.c.m. guys
> >aren't going to be building switching regulators, and switching
> >regulators generally aren't more efficient at these power levels
> >anyhow--their quiescent current draw's too high.
>
> True. However, switching regulators usually have some manner of load
> shedding when the supply voltage is insufficient. Below that
> threshold, the current drain is usually in nanoamps.
>
> >(I've made a study of designing microwatt switchers, from scratch.
> >It's possible, but wholly inappropriate here.)
>
> You're ahead of me. I've never designed anything in that low power
> class. Different world. Can you point me to a suitable (or close to
> suitable) regulator chip?

There aren't any ICs with low enough Iq, at least not that I know of.
I used discrete transistors.

> >Not so fast... The advantage of the thin-film PV panels is that
> >(appropriate) panels excel at producing power even in dim light.
> >Polycrystalline silicon panels don't.
> >The array I suggested for experimentation is thin-film for that
> >reason--so it can work in indoor light levels.
>
> Decisions, decisions, and more decisions. Polycrystaline has a cost
> advantage and is more efficient than single layer thin-film. Well, if
> I wanted to go cheap, I would use amorphous cells and mold them into
> the plastic case. For small solar cells, the cost of monocrystaline
> isn't all that much more (i.e. most of the cost is in packaging and
> handling) but won't work well with indoor lighting. So, I guess
> thin-film is the least disgusting.
> <http://en.wikipedia.org/wiki/Solar_powered_calculator>
> "Solar calculators may not work well in indoor
> conditions under ambient lighting as sufficient lighting
> is not available."

You can scavenge a PV from a cheap solar calculator, as low as $1. I
also linked to a part from Goldmine-elec.com.

Polycrystalline cells put out lots more in bright light, but AFAIK,
all solar calculators (and calipers, for that matter), use the
amorphous (thin-film) cells for the low-light performance. Cost might
also be a factor.

> >> The next question is for how long will it run? Assuming the calipers
> >> can handle 3.0VDC without damage, how long will a junk 100UF
> >> electrolytic cap run the calipers?
>
> >a) How long will it run? Not nearly long enough, and b) 3.0VDC is
> >waayyy too risky for my blood. 20uA will discharge 100uF from 2.0V to
> >1.35V in 3.25 seconds.
>
> I used 1000uF elsewhere in my calcs, but slipped here and used 100uF
> instead. Sorry.
>
> I think you might be a bit too conservative. 5ua leakage is high.
> Most of the spec sheets I've skimmed show 1-2ua for a typical 1F 5.5V
> super-cap.
>
> >Of the setup I suggested, the most marginal part is the itty bitty PV
> >panel (its output is on the low side). Dark leakage on my much-larger
> >10x55mm calculator panel is about 8uA @ 1.7V bias.
>
> The alternative is to lose approximately 0.3V in a series Schottky
> diode. That's about 20% of the power budget, which is probably too
> much.

I believe the panels put out a high enough overvoltage that the diode
loss doesn't matter--it's only going to get wasted in the LED shunt
regulators any how. I'll check.

MEASUREMENTS
Panel: 4-section 10x50mm panel, from a (retired) TI calculator:

Lighting 1: 1.8V (open), 18.5uA (short-circuit)
Lighting 2: 2.5V (open), 300uA (short-circuit)

[1] Modest indoor light (indirect sunlight, filtering through blinds,
measured from the ceiling bounce).
[2] 2' from 20W halogen bulb.

So, a 1n4148 drops too much for comfort. A BAT54 drops about 150mV
forward at these currents, and leaks a fraction of a uA at these
temperatures and reverse biases. Or, you could omit the diode and
just let the thing power down in the shade.

> >The supercap works wonderfully well. Charge 0.6F to 1.8V, and you've
> >got 4 hours' runtime until you reach the 1.35V battery-low display-
> >starts-blinking level. (Assuming 20uA total draw, to allow for some
> >leakage.)
>
> Ok. You've sold me. I was trying to see what could be done with
> commodity electrolytic caps. Also, super-caps fail to appreciate high
> humidity, which may become a problem.
>
>
>
> >> <http://www.kpsec.freeuk.com/capacit.htm>
> >> From 1.37V is roughly 50% of full 3.0VDC charge. That's about 80% of
> >> 1RC time constant. 1RC is:
> >> 0.8 * 100K * 1000uF = 80 seconds
> >> That's probably enough to make a few measurements. Any longer and a
> >> super-cap will probably be needed. Picking 50% of full charge out of
> >> the hat is rather convenient, as it makes the time to charge from zero
> >> to the dropout point the same 80 seconds (yes, I'm lazy). Whether the
> >> user really wants to wait 1.5 minutes under a desk lamp for the
> >> calipers to be usable is dubious. Of course, a longer run time, means
> >> a longer charge time. For example, a 1F 5V 1ua leakage super-cap,
> >> will run the calipers for 80,000 seconds, but will also take 80,000
> >> seconds to charge.
>
> >Not 80,000s. Expose the PV to sunlight (or directly to a lamp), and
> >it'll charge (initially) >50x faster. You'd only have to do that
> >once. Indoors, the PV would keep it topped off, that's the idea.
>
> Yep. However, I screwed up. The discharge load is:
> 1.5VDC / 15uA = 100K ohms
> However, the charging ESR is much less.
> 3.0VDC / 2ma = 1.5K
> It will certainly be higher a lower illumination levels. Checking my
> junk cell under random room lighting conditions, and again scaling for
> size, I get:
> 0.333 * 0.55v / 0.02mA = 9.2K
> I don't have a small thin film panel to test. (I have 90watt panel,
> but that's a bit much for scaling to caliper size).
>
> >Alternatively, an electrolytic works, but gives a caliper that quickly
> >quits if you accidentally shadow it.
>
> Not if you do exactly like it's done with a calculator. When the cell
> is shaded, it runs on battery. A silver-oxide battery holds:
> 1.5v * 150 mA-Hr = 22.5 milliwatt-Hrs
> and will deliver most of that before the voltage drops to unusable
> levels.
>
> The super cap will deliver (very roughly):
> 1.5v * 15uA * 4Hr = 90 microwatt-Hrs
>
> >There are much smaller supercaps--0.02F--used in cellphones. That's
> >another option / compromise. Leakage should be better too.
>
> Overview of CDE super-caps:
> <http://www.cde.com/catalogs/EDL.pdf>
> Some interesting notes on charge time and lifetime near the bottom.
>
> >> In my never humble opinion, what makes more sense is to do it exactly
> >> like the typical solar powered calculator. They all have one or two
> >> LR44 batteries inside. However, the solar cell does NOT charge the
> >> battery. When you turn the calculator on, and there's enough light to
> >> run from the solar cell, the battery is essentially disconnected. When
> >> there's not enough light to run the calculator, it runs off the
> >> battery. No waiting to charge a capacitor from the solar cell.
>
> >That uses the PV as, basically, a battery-extender. That's fine, but
> >complex--you need a micro-power switch to disconnect the battery, etc.
> >(A diode drops waayyy too much voltage.) That puts it out of the
> >realm of a simple project that can fit into the existing caliper.
>
> There has to be a chip in the calipers anyway to count pulses, run the
> display, and deal with the push buttons. Adding a power management
> feature does not add much real estate or complexity. However, if
> you're thinking of a retrofit, I suspect something could be done with
> a separate switcher chip.

If we're designing it from scratch, we just wouldn't use so darn much
power to start with. Then, a PV panel and a capacitor are all you
need.

Switcher chips just don't do well on 20uA power input.

> >> If you're into high tech, there are various energy scavenging devices
> >> that can also power the calipers.
> >> <http://en.wikipedia.org/wiki/Energy_harvesting>
> >> With only 22.5 microwatts required, it might be possible to power the
> >> device with a wind up key, piezo pressure, body heat, kinetic magnetic
> >> generator, etc. I kinda like the idea of a wind up caliper.
>
> >Windup would be fun--steampunk.
>
> In the late 1960's, I designed and built a paging receiver, that
> produced the message output on a 1/4" wide roll of paper tape. Battery
> power to the mechanics for such a portable device was impossible. So,
> I went to a wind up coil spring mechanism. I've been somewhat of a
> fan of spring power ever since.
>
> >The "real" solution is to design the caliper to draw less current in
> >the first place, like Mitutoyo and Starrett. If you've done that,
> >solar-powering is a snap, but then, if the battery lasts years, you
> >don't need solar power, do you?
>
> Agreed. It would be like a digital watch, which typically has a 10
> year battery life. However, the solar cell is still a problem because
> of the dark current (reverse leakage). An isolating Schottky diode
> can reduce that, but then the solar cell would need to be about 20%
> larger to compensate for the added loss.
>
> Another problem is that it would be no fun. Windup calipers offer a
> far more entertaining problem to solve.

Windup calipers--that's cool!

--
Cheers,
James Arthur

== 3 of 5 ==
Date: Fri, Nov 25 2011 7:22 am
From: dagmargoodboat@yahoo.com

On Nov 25, 1:29 am, Jeff Liebermann <je...@cruzio.com> wrote:
> On Thu, 24 Nov 2011 21:46:48 -0800, Jeff Liebermann <je...@cruzio.com>
> wrote:
>
> >>> The next question is for how long will it run? Assuming the calipers
> >>> can handle 3.0VDC without damage, how long will a junk 100UF
> >>> electrolytic cap run the calipers?
>
> >>a) How long will it run? Not nearly long enough, and b) 3.0VDC is
> >>waayyy too risky for my blood. 20uA will discharge 100uF from 2.0V to
> >>1.35V in 3.25 seconds.
>
> Trying the same calc using the super-cap formula from Pg 6 of:
> <http://www.cde.com/catalogs/EDL.pdf>
>
> t = C delta V / I
> t = C[V0-(i*R)-V1] / (i+iL)
> where:
> t: Back-up time (sec)
> C: Capacitance of Type EDL (Farads)
> V0: Applied voltage (Volts)
> V1: Cut-off voltage (Volts)
> i: Current during back-up (Amps)
> iL: Leakage current (Amps)
> R: Internal resistance (ohms) at 1 kHz
>
> For this example, I'll use a 0.1F (type F) 5.5V 100 ohm cap.
> The low end of the tolerance range might drop this to 0.08F.
> V0 = 2.0V, V1 = 1.4V, i = 15uA, iL = 2uA

That cap is 14x10mm, pretty humungous. You don't need 5.5v, so the
'EN' type, at 7x2mm and 0.2F might be a better fit.

> Plugging in:
> t = C[V0-(i*R)-V1] / (i+iL)
> t = 0.08F[2.0V-(15uA*100ohms)-1.4V]/(15uA+2uA)
> t = 2800 sec = 47 minutes.
> Not bad.

I calculated the caliper as being a constant-current drain on the
super cap, then applied Q=CV. Actual current drain drops a tad with
falling Vdd, so my approximation is probably slightly conservative.

> I guess the protective case that most calipers use will need a clear
> plastic window to keep it charged. Maybe another window on top of my
> toolbox.

Yep. Another retro-fit possibility is to fit a supercap in the
caliper, and a lithium-AA (1.65v) in the caliper case that recharges
the supercap when not in use.

That'll last forever (about 10years on the 'AA'), runs for hours per
charge, fits the case easily, and doesn't need a PV or any fancy
circuitry. The PAS920 I linked before costs 5/$1 surplus, from
Goldmine-elec.com.

--
Cheers,
James Arthur

== 4 of 5 ==
Date: Fri, Nov 25 2011 2:31 pm
From: "krw@att.bizzzzzzzzzzzz"

On Fri, 25 Nov 2011 07:06:57 -0800 (PST), dagmargoodboat@yahoo.com wrote:

>On Nov 25, 12:46 am, Jeff Liebermann <je...@cruzio.com> wrote:
>> On Thu, 24 Nov 2011 18:13:15 -0800 (PST), dagmargoodb...@yahoo.com
>> wrote:
>>
>> I found this, which calculates and measures caliper battery life:
>> <http://www.davehylands.com/Machinist/Caliper-Batteries/>
>
>Yes, good site. I linked to it earlier in this thread.
>
>> >Small, cheap and simple are the main factors here. The r.c.m. guys
>> >aren't going to be building switching regulators, and switching
>> >regulators generally aren't more efficient at these power levels
>> >anyhow--their quiescent current draw's too high.
>>
>> True. However, switching regulators usually have some manner of load
>> shedding when the supply voltage is insufficient. Below that
>> threshold, the current drain is usually in nanoamps.
>>
>> >(I've made a study of designing microwatt switchers, from scratch.
>> >It's possible, but wholly inappropriate here.)
>>
>> You're ahead of me. I've never designed anything in that low power
>> class. Different world. Can you point me to a suitable (or close to
>> suitable) regulator chip?
>
>There aren't any ICs with low enough Iq, at least not that I know of.
>I used discrete transistors.

There are some pretty good ones, designed for USB applications, but I don't
thing they're quite good enough for this. The TPS6205x Iq is around 5uA to and
in shutdown less than 2uA. You're looking for something an order of magnitude
better than this?

<...>

== 5 of 5 ==
Date: Fri, Nov 25 2011 9:28 pm
From: dagmargoodboat@yahoo.com

On Nov 25, 5:31 pm, "k...@att.bizzzzzzzzzzzz"
<k...@att.bizzzzzzzzzzzz> wrote:
> On Fri, 25 Nov 2011 07:06:57 -0800 (PST), dagmargoodb...@yahoo.com wrote:
> >On Nov 25, 12:46 am, Jeff Liebermann <je...@cruzio.com> wrote:
> >> On Thu, 24 Nov 2011 18:13:15 -0800 (PST), dagmargoodb...@yahoo.com
> >> wrote:
>
> >> I found this, which calculates and measures caliper battery life:
> >> <http://www.davehylands.com/Machinist/Caliper-Batteries/>
>
> >Yes, good site. I linked to it earlier in this thread.
>
> >> >Small, cheap and simple are the main factors here. The r.c.m. guys
> >> >aren't going to be building switching regulators, and switching
> >> >regulators generally aren't more efficient at these power levels
> >> >anyhow--their quiescent current draw's too high.
>
> >> True. However, switching regulators usually have some manner of load
> >> shedding when the supply voltage is insufficient. Below that
> >> threshold, the current drain is usually in nanoamps.
>
> >> >(I've made a study of designing microwatt switchers, from scratch.
> >> >It's possible, but wholly inappropriate here.)
>
> >> You're ahead of me. I've never designed anything in that low power
> >> class. Different world. Can you point me to a suitable (or close to
> >> suitable) regulator chip?
>
> >There aren't any ICs with low enough Iq, at least not that I know of.
> >I used discrete transistors.
>
> There are some pretty good ones, designed for USB applications, but I don't
> thing they're quite good enough for this. The TPS6205x Iq is around 5uA to and
> in shutdown less than 2uA. You're looking for something an order of magnitude
> better than this?
>
> <...>

http://www.ti.com/lit/ds/symlink/tps62050.pdf

From the graph on the front page, it looks like n = ~35% @ 15uA
output. That's actually very good. Thanks.

My designs were mostly boost topology, so there may be ICs I didn't
consider (plus new ICs I haven't seen). I did some nutty stuff, like
nano-amp oscillators and micro-amp switchers that were roughly 75%
efficient.

--
Cheers,
James Arthur

==============================================================================
TOPIC: Garmin vs Tomtom
http://groups.google.com/group/sci.electronics.repair/t/05bb6bddf1b8fc41?hl=en
==============================================================================

== 1 of 3 ==
Date: Fri, Nov 25 2011 3:40 am
From: Bruce Esquibel

hrhofmann@att.net <hrhofmann@att.net> wrote:

> I see advertisements for Garmin and TomTom GPS units, with lifetime
> map updates and same size 5" screens for the same prices. Does anyone
> have any experience with both units that can state a preference. Also,
> I wonder how the companies behind the units are set financially, a
> lifetime update is meaningless if the company goes out of business.

Which is something to reckon with.

Keep in mind the usefulness of stand-alone gps units is in a decline with
the advent of the cell phones and tables that have gps in them. That and
even economy cars have some built-in option these days, although expensive.

I doubt if either company is going to tank soon, but it's sort of like being
in the horseshoe business with Ford building the model T plant down the
road.

-bruce
bje@ripco.com

== 2 of 3 ==
Date: Fri, Nov 25 2011 4:01 am
From: Jeffrey Angus

On 11/25/2011 5:40 AM, Bruce Esquibel wrote:
> Keep in mind the usefulness of stand-alone gps units is in a decline with
> the advent of the cell phones and tables that have gps in them.

That's like saying screwdrivers and knives are in decline because of
Swiss Army knives.

> I doubt if either company is going to tank soon, but it's sort of like being
> in the horseshoe business with Ford building the model T plant down the
> road.

Stand along GPS/mapping units aren't in the same category as buggy
whips. They certainly do a better job at being GPS units then the
try to do everything under the sun iPads.

Jeff

--
"Everything from Crackers to Coffins"

== 3 of 3 ==
Date: Fri, Nov 25 2011 5:15 am
From: Tim Schwartz

Good morning all,

I've got a Garmin 1490T (T= traffic report receiver) which I'm quite
happy with. That said, any of the 3 major brands (Garmin, TomTom or
Magellian) are likely to be just fine. I would have a look at the user
interface, and see which you like best.

I would consider any of these a 5-7 year device at best. At some point
the internal battery will die, or some other failure will occur, or
you'll just loose the darn thing. Or the new ones will be so much
better that you'll want one.

I've found the dedicated navigation unit far superior to ones on
phones, and much more economical than ones built into cars, especially
if you have several cars in your family.

As another point against built in units, Auto manufacturers charge
obscene amounts for updates. I had a friend whose dealer quoted $700
for the new DVD set for his 2005 car. Almost as offensive as charging
$500 for a USB interface, which likely cost them about $6.00. ($99
radios have them built in.)

Regards,
Tim Schwartz
Bristol Electronics

==============================================================================
TOPIC: Sharp GF 990G ghetto blaster
http://groups.google.com/group/sci.electronics.repair/t/87b2eef7dbd95b2e?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Nov 25 2011 6:20 am
From: "N_Cook"

Back working again with all 7 bands replaced with new silicone rubber bands.
I wonder how long they will last. I read last week that silicone rubber is
not as tolerant of cyclic loading, which dynamic use of this material I
suppose is so, especially around the smaller drive bobbins

==============================================================================
TOPIC: Simple tone control?
http://groups.google.com/group/sci.electronics.repair/t/eb3fafaa60fb8246?hl=en
==============================================================================

== 1 of 2 ==
Date: Fri, Nov 25 2011 1:25 pm
From: DaveC

A general question:

Should pots used in the audio tone filter circuits be audio (log) taper? Or
does this apply only to volume pots?

Thanks.

== 2 of 2 ==
Date: Fri, Nov 25 2011 1:30 pm
From: spam@spam.com (Don Pearce)

On Fri, 25 Nov 2011 13:25:37 -0800, DaveC <invalid@invalid.net> wrote:

>A general question:
>
>Should pots used in the audio tone filter circuits be audio (log) taper? Or
>does this apply only to volume pots?
>
>Thanks.

Linear

==============================================================================
TOPIC: Curious longlived battery
http://groups.google.com/group/sci.electronics.repair/t/5a954e0d64a72bc5?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Nov 25 2011 5:36 pm
From: vjp2.at@at.BioStrategist.dot.dot.com

ca 1995 I bought some 7yr diver watches from Woolworth. WHen they doed I
tried to replace the battery but the entire watch was sealed in silicone and
could not be salvaged. I had tied one of those watched to the handlebar of my
bicycle, face towards the sky. It still runs. Is it because the battery
remained flat? It is kinda miraculous!

- = -
Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
http://www.panix.com/~vjp2/vasos.htm
---{Nothing herein constitutes advice. Everything fully disclaimed.}---
[Homeland Security means private firearms not lazy obstructive guards]
[Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]

==============================================================================
TOPIC: Aerial wifi antennae
http://groups.google.com/group/sci.electronics.repair/t/7919aac51f31b136?hl=en
==============================================================================

== 1 of 4 ==
Date: Fri, Nov 25 2011 5:40 pm
From: vjp2.at@at.BioStrategist.dot.dot.com

Since HDTV came out, I basically get one different station in each room I
move the TV to. Someone joked that the reason HDTV was invented was to force
people off of aerial TV. Any anecdotes? I tried some booster antennae and
also a thru the AC antennae to no avail. The best antenna was one from a
computer TV card. My uncle has had some better luck with a roof antenna.
Are people out there silly enough to waste their time and money watching
cable?

== 2 of 4 ==
Date: Fri, Nov 25 2011 5:53 pm
From: "Charlie"

<vjp2.at@at.BioStrategist.dot.dot.com> wrote in message
news:japg2d$goa$4@reader1.panix.com...
> Since HDTV came out, I basically get one different station in each room I
> move the TV to. Someone joked that the reason HDTV was invented was to
> force
> people off of aerial TV. Any anecdotes? I tried some booster antennae and
> also a thru the AC antennae to no avail. The best antenna was one from a
> computer TV card. My uncle has had some better luck with a roof antenna.
> Are people out there silly enough to waste their time and money watching
> cable?
>
> - = -
> Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
> http://www.panix.com/~vjp2/vasos.htm
> ---{Nothing herein constitutes advice. Everything fully disclaimed.}---
> [Homeland Security means private firearms not lazy obstructive guards]
> [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]

Google is your friend.

I built the one here http://www.tvantennaplans.com/ when digital
transmission was becoming more popular but was not yet he only game around.

I hooked it up to my 32" Vizio and was able to receive all the networks and
a few other providers.
I am in the flat land of Florida and with the antenna on the floor and about
4' above ground level.
It is fairly directional but one day when cable was out I was the only one
in the neighborhood watching he tube.

Charlie

== 3 of 4 ==
Date: Fri, Nov 25 2011 5:56 pm
From: "Charlie"

"Charlie" <left@thestation.com> wrote in message
news:japgpn$1lg$1@dont-email.me...
>
> <vjp2.at@at.BioStrategist.dot.dot.com> wrote in message
> news:japg2d$goa$4@reader1.panix.com...
>> Since HDTV came out, I basically get one different station in each room I
>> move the TV to. Someone joked that the reason HDTV was invented was to
>> force
>> people off of aerial TV. Any anecdotes? I tried some booster antennae and
>> also a thru the AC antennae to no avail. The best antenna was one from a
>> computer TV card. My uncle has had some better luck with a roof antenna.
>> Are people out there silly enough to waste their time and money watching
>> cable?
>>
>> - = -
>> Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus,
>> BioStrategist
>> http://www.panix.com/~vjp2/vasos.htm
>> ---{Nothing herein constitutes advice. Everything fully disclaimed.}---
>> [Homeland Security means private firearms not lazy obstructive guards]
>> [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime
>> Bimbos]
>
> Google is your friend.
>
> I built the one here http://www.tvantennaplans.com/ when digital
> transmission was becoming more popular but was not yet he only game
> around.
>
> I hooked it up to my 32" Vizio and was able to receive all the networks
> and a few other providers.
> I am in the flat land of Florida and with the antenna on the floor and
> about 4' above ground level.
> It is fairly directional but one day when cable was out I was the only one
> in the neighborhood watching he tube.
>
> Charlie

BTW I did not use the reflectors shown near the end

== 4 of 4 ==
Date: Fri, Nov 25 2011 7:48 pm
From: Jeff Liebermann

On Sat, 26 Nov 2011 01:40:29 +0000 (UTC),
vjp2.at@at.BioStrategist.dot.dot.com wrote:

>Since HDTV came out, I basically get one different station in each room I
>move the TV to. Someone joked that the reason HDTV was invented was to force
>people off of aerial TV. Any anecdotes? I tried some booster antennae and
>also a thru the AC antennae to no avail. The best antenna was one from a
>computer TV card.

Get an outside antenna.
There's no such thing as an HDTV antenna. They're VHF, UHF, or both.
The amplifier goes near the antenna on the roof.
Use RG-6/u coax, not twinlead.
Try not to fall off the roof.

>My uncle has had some better luck with a roof antenna.

No luck required. Indoor antennas only work in strong signal areas.
You've supplied no numbers or location, so you only get general
advice.

>Are people out there silly enough to waste their time and money watching
>cable?

I pay for DirecTV satellite. The local OTA (over the air) broadcast
programming is awful. I receive HDTV OTA fairly well, but only with a
rotator and self designed antenna and amplifier.

Antenna aiming:
<http://www.tvfool.com>

Antenna comparisons:
<http://www.hdtvprimer.com/ANTENNAS/comparing.html>

The basics of HDTV:
<http://www.hdtvprimer.com>

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

==============================================================================
TOPIC: Panasonic NV-J22 video output to Archos 5
http://groups.google.com/group/sci.electronics.repair/t/0420837a4eaefa79?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Nov 25 2011 6:44 pm
From: myfathersson

On Nov 24, 6:52 pm, b <reverend_rog...@yahoo.com> wrote:
> On Nov 24, 12:43 am, myfathersson <licensedtoqu...@gmail.com> wrote:
>
>
>
>
>
>
>
>
>
> > On Nov 23, 6:04 pm, b <reverend_rog...@yahoo.com> wrote:
>
> > > On Nov 23, 11:04 pm, myfathersson <licensedtoqu...@gmail.com> wrote:
>
> > > > I am hoping this question isnt too non-specific or the answer too
> > > > obvious but I just shlepped this Panasonic multi-system TV which I
> > > > originally brought from the US to UK back again to record lots of PAL
> > > > videos to the Archos. Now however there doesnt seem to be any video
> > > > output at all.
>
> > > > I can see the sound on the bar graphic input on the Archos but the
> > > > Archos doesnt report any input signal. All I am doing is to out put
> > > > the signal from the video out of the Panasonic to the video in on the
> > > > Archos DVR station.
>
> > > I'm confused by your post. Are you talking about a Panasonic multi
> > > standard tv, or a Panasonic vhs video recorder?
> > > -B
>
> > Sorry about the confusion
>
> > Not sure how it got caused
>
> > The Panasonic NV-J22 is a VHS video cassette recorder. I am trying to
> > transfer the contents of VHS cassettes onto the Archos 5
>
> we need to narrow this down. First ascertain that the vhs is
> outputting video. For all we know, the heads might be dirty. Try
> connecting it to a normal tv set. It should sync down to 50hz pal
> frame rate, and I imagine you'd get a black and white picture....
> -b

OK I think you are right: I will have to find some sort of converter
for the European output cable to a coax connector and try that output
into a TV. The Archos may well not report ANY input unless the pic is
perfect.

==============================================================================
TOPIC: Nakamichi CD Player 3 - needs to heat before it's able to read disc
http://groups.google.com/group/sci.electronics.repair/t/7fae55556abb29a6?hl=en
==============================================================================

== 1 of 2 ==
Date: Fri, Nov 25 2011 7:51 pm
From:

Hi,

I have a Nakamichi CD Player 3, circa 1992, that is a terrific player, but
requires to be warmed up for about 1.5 hours before it is able to read the
disc; After this point, then it works fine.

I am not sure why the warm up needed, but it is drag when you have to build
in this lead-time into your CD listening.

Any thoughts as to why this is happening and steps to remedy will be most
appreciated..

Thanks

== 2 of 2 ==
Date: Fri, Nov 25 2011 8:04 pm
From: "Phil Allison"

<andrewsave@hotmail.com>
>
> I have a Nakamichi CD Player 3, circa 1992, that is a terrific player, but
> requires to be warmed up for about 1.5 hours before it is able to read the
> disc; After this point, then it works fine.
>
> I am not sure why the warm up needed, but it is drag when you have to
> build in this lead-time into your CD listening.
>
> Any thoughts as to why this is happening and steps to remedy will be most
> appreciated..

** Might be sticky lubricant on moving parts.

Do not tackle it yourself - take it to an experienced audio tech.

.... Phil

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Google Groups: http://groups.google.com/?hl=en

sci.electronics.repair - 11 new messages in 6 topics - digest

12:28 AM Penedão 0 comments

sci.electronics.repair
http://groups.google.com/group/sci.electronics.repair?hl=en

sci.electronics.repair@googlegroups.com

Today's topics:

* Panasonic NV-J22 video output to Archos 5 - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/0420837a4eaefa79?hl=en
* Garmin vs Tomtom - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/05bb6bddf1b8fc41?hl=en
* Philips TV -- dual schottky - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/b3d88bd825144880?hl=en
* Repaired Harbor Freight digital caliper - 4 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/d8587e526bcdbeaf?hl=en
* Editing a pdf file ... - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/e7a871e294322579?hl=en
* Winter Special Electric Room Heater - Buy 1 Get 1 Free + Stylish Branded
Watch - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/108bb21fe8393503?hl=en

== 1 of 1 ==
Date: Thurs, Nov 24 2011 3:52 pm
From: b

On Nov 24, 12:43 am, myfathersson <licensedtoqu...@gmail.com> wrote:
> On Nov 23, 6:04 pm, b <reverend_rog...@yahoo.com> wrote:
>
>
>
> > On Nov 23, 11:04 pm, myfathersson <licensedtoqu...@gmail.com> wrote:
>
> > > I am hoping this question isnt too non-specific or the answer too
> > > obvious but I just shlepped this Panasonic multi-system TV which I
> > > originally brought from the US to UK back again to record lots of PAL
> > > videos to the Archos. Now however there doesnt seem to be any video
> > > output at all.
>
> > > I can see the sound on the bar graphic input on the Archos but the
> > > Archos doesnt report any input signal. All I am doing is to out put
> > > the signal from the video out of the Panasonic to the video in on the
> > > Archos DVR station.
>
> > I'm confused by your post. Are you talking about a Panasonic multi
> > standard tv, or a Panasonic vhs video recorder?
> > -B
>
> Sorry about the confusion
>
> Not sure how it got caused
>
> The Panasonic NV-J22 is a VHS video cassette recorder. I am trying to
> transfer the contents of VHS cassettes onto the Archos 5

we need to narrow this down. First ascertain that the vhs is
outputting video. For all we know, the heads might be dirty. Try
connecting it to a normal tv set. It should sync down to 50hz pal
frame rate, and I imagine you'd get a black and white picture....
-b

== 1 of 2 ==
Date: Thurs, Nov 24 2011 4:06 pm
From: Archon

On 11/24/2011 11:25 AM, hrhofmann@att.net wrote:
> I see advertisements for Garmin and TomTom GPS units, with lifetime
> map updates and same size 5" screens for the same prices. Does anyone
> have any experience with both units that can state a preference. Also,
> I wonder how the companies behind the units are set financially, a
> lifetime update is meaningless if the company goes out of business.
I bought the Magellan Roadmate with free lifetime map updates plus a
bigger screen to replace a TomTom that wanted $80 for a map update. (The
TomTom was excellent by the way). First thing I noticed was the Magellan
does not have the "avoid toll road option", second thing I noticed it
doesn't know how to get anywhere! It tried to make a 20 minute detour on
freeways to get to my house which was 1/2 mile away,(most use of
freeways), on the "least use of freeways" option it took me along
country roads for an hour. Totally useless. there seems to be no logic
to the routes it chooses. In NJ I hate toll roads so that is a
significant requirement for me.
JC

== 2 of 2 ==
Date: Thurs, Nov 24 2011 6:50 pm
From: Rich Webb

On Thu, 24 Nov 2011 22:39:19 +0000, Peter Hill
<peter.usenet1@nospam.demon.co.uk> wrote:

>On Thu, 24 Nov 2011 15:01:47 -0500, Rich Webb
><bbew.ar@mapson.nozirev.ten> wrote:
>
>>On Thu, 24 Nov 2011 09:31:10 -0800, "William Sommerwerck"
>><grizzledgeezer@comcast.net> wrote:
>>
>>>One of the things I like about Garmin is the optional "beanbag" dash mount,
>>>which for most (but not all) users works much better than the windshield
>>>suction cup. (I don't know if there's a comparable mount for the TomTom.)
>>
>>WRT mounts, I'm sold on the "sit on the dash with non-slip feet" style.
>>Keeps in reach for bluetooth (phone) or to check the traffic maps.
>
>Wouldn't do for me. My dash has a grain effect so suction feet don't
>work.
>
>It also has a sloping dash. What holds the bean bag in place?

Here also, the usual pebble-grain vinyl. Mine is an older model of this
<https://buy.garmin.com/shop/shop.do?pID=63953> that I used with an
older Garmin. The feet bottoms have the soft, high-friction stuff that
looks sort of like velvet; I believe that a similar material is used as
a drawer liner. No suction, just friction. It *will* slide off given
enough acceleration or, I suppose, if I tried jumping the Snake River
Canyon but in normal driving it just sits in place quite nicely.

--
Rich Webb Norfolk, VA

==============================================================================
TOPIC: Philips TV -- dual schottky
http://groups.google.com/group/sci.electronics.repair/t/b3d88bd825144880?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Nov 24 2011 5:51 pm
From: "Arfa Daily"

"mkr5000" <mikerbgr@gmail.com> wrote in message
news:3111226.55.1321981106144.JavaMail.geo-discussion-forums@yqie15...
> Model number is 19pfl3403 (a real dog I understand) -- anyway, not getting
> 5.2v but around 4.
>
> I'm not a repair guy but electronics is my life and looks like it may be
> the dual schottky rectifier -- good AC voltage out of the transformer.
>
> part is a 60v 10a dual -- wonder if a 45v part will suffice? (it's what I
> have).
>
> after all they're using a 100v schottky for the 13v supply so it sounds
> like it'll work. THANKS if you know off hand.

It's a bit unusual for diodes - even Schottkies - to go 'weird'. Commonly,
they fail short circuit. I would have thought that a far more likely cause
of your low voltage, is the filter cap following the rectifier. If that goes
open or high ESR, you will get a low reading of the DC volts that you're
expecting, the reason being that if you look at the voltage across the cap
with a 'scope, it will be hashy not pure DC, so the average that the meter
tries to make of it, will be lower. It is very very common for filter caps
following Schottky diodes in SMPs, to fail in this way.

Arfa

== 1 of 4 ==
Date: Thurs, Nov 24 2011 6:13 pm
From: dagmargoodboat@yahoo.com

On Nov 24, 5:20 pm, Jeff Liebermann <je...@cruzio.com> wrote:
> On Wed, 23 Nov 2011 06:45:46 -0800 (PST), dagmargoodb...@yahoo.com
> wrote:
>
> >The max. solar panel voltage doesn't matter--the LED regulator clamps
> >the solar panel voltage, taking care of that.
>
> Yeah, but shunt regulators and leaky super-caps are not really
> appropriate for micropower devices. They waste power.

Small, cheap and simple are the main factors here. The r.c.m. guys
aren't going to be building switching regulators, and switching
regulators generally aren't more efficient at these power levels
anyhow--their quiescent current draw's too high.

(I've made a study of designing microwatt switchers, from scratch.
It's possible, but wholly inappropriate here.)

> In a previous message, James Arthur measured:
> Drain: 13.5uA (off), 14.5uA (on)
> Battery low threshold (blinking display): 1.37V
> Lowest operating voltage: 1.01V
>
> Nominal voltage on a silver oxide battery is 1.5V. Therefore, the
> operating power is:
> 1.5VDC * 15uA = 22.5 microwatts.
> From the standpoint of a resistive load, that's about:
> 1.5VDC / 15 uA = 100K ohms
>
> The first question is whether a small solar cell will product 22.5
> microwatts. Testing a somewhat oversized polycrystaline cell that I
> found in my junk box (quality unknown), it produces 3.0VDC at 6ma with
> a short circuit load (my milliamps guesser). My guess(tm) is that
> this cell is about three times as big as will conveniently fit on the
> calipers, so I'll just cut the current to 2ma . Delivered power with
> my desk lamp is 6 milliwatts. Yeah, it will a 22.5 microwatt load.

Not so fast... The advantage of the thin-film PV panels is that
(appropriate) panels excel at producing power even in dim light.
Polycrystalline silicon panels don't.

The array I suggested for experimentation is thin-film for that
reason--so it can work in indoor light levels.

> The next question is for how long will it run? Assuming the calipers
> can handle 3.0VDC without damage, how long will a junk 100UF
> electrolytic cap run the calipers?

a) How long will it run? Not nearly long enough, and b) 3.0VDC is
waayyy too risky for my blood. 20uA will discharge 100uF from 2.0V to
1.35V in 3.25 seconds.

Of the setup I suggested, the most marginal part is the itty bitty PV
panel (its output is on the low side). Dark leakage on my much-larger
10x55mm calculator panel is about 8uA @ 1.7V bias.

The supercap works wonderfully well. Charge 0.6F to 1.8V, and you've
got 4 hours' runtime until you reach the 1.35V battery-low display-
starts-blinking level. (Assuming 20uA total draw, to allow for some
leakage.)

> <http://www.kpsec.freeuk.com/capacit.htm>
> From 1.37V is roughly 50% of full 3.0VDC charge. That's about 80% of
> 1RC time constant. 1RC is:
> 0.8 * 100K * 1000uF = 80 seconds
> That's probably enough to make a few measurements. Any longer and a
> super-cap will probably be needed. Picking 50% of full charge out of
> the hat is rather convenient, as it makes the time to charge from zero
> to the dropout point the same 80 seconds (yes, I'm lazy). Whether the
> user really wants to wait 1.5 minutes under a desk lamp for the
> calipers to be usable is dubious. Of course, a longer run time, means
> a longer charge time. For example, a 1F 5V 1ua leakage super-cap,
> will run the calipers for 80,000 seconds, but will also take 80,000
> seconds to charge.

Not 80,000s. Expose the PV to sunlight (or directly to a lamp), and
it'll charge (initially) >50x faster. You'd only have to do that
once. Indoors, the PV would keep it topped off, that's the idea.

Alternatively, an electrolytic works, but gives a caliper that quickly
quits if you accidentally shadow it.

There are much smaller supercaps--0.02F--used in cellphones. That's
another option / compromise. Leakage should be better too.

> There are low voltage DC-DC boost/buck switching regulator chips
> available that can tolerate a wide range of input voltages, and
> deliver a constant 1.5VDC.
>
> In my never humble opinion, what makes more sense is to do it exactly
> like the typical solar powered calculator. They all have one or two
> LR44 batteries inside. However, the solar cell does NOT charge the
> battery. When you turn the calculator on, and there's enough light to
> run from the solar cell, the battery is essentially disconnected. When
> there's not enough light to run the calculator, it runs off the
> battery. No waiting to charge a capacitor from the solar cell.

That uses the PV as, basically, a battery-extender. That's fine, but
complex--you need a micro-power switch to disconnect the battery, etc.
(A diode drops waayyy too much voltage.) That puts it out of the
realm of a simple project that can fit into the existing caliper.

> If you're into high tech, there are various energy scavenging devices
> that can also power the calipers.
> <http://en.wikipedia.org/wiki/Energy_harvesting>
> With only 22.5 microwatts required, it might be possible to power the
> device with a wind up key, piezo pressure, body heat, kinetic magnetic
> generator, etc. I kinda like the idea of a wind up caliper.

Windup would be fun--steampunk.

The "real" solution is to design the caliper to draw less current in
the first place, like Mitutoyo and Starrett. If you've done that,
solar-powering is a snap, but then, if the battery lasts years, you
don't need solar power, do you?

--
Cheers,
James Arthur

== 2 of 4 ==
Date: Thurs, Nov 24 2011 7:16 pm
From: "DoN. Nichols"

On 2011-11-23, Bob Engelhardt <bobengelhardt@comcast.net> wrote:
> Winston wrote:
>> Bob Engelhardt wrote:
>>> The wiki ckt has a current-limiting resistor in series with the voltage
>>> source. Not so the posted ckt.
>
>> It *is* in the posted circuit.
>> Sort of. :)
>>
>> As James mentions, the internal resistance of the PV
>> cell is the current-limiting resistor.
>
> I meant the capacitor voltage source. Is its internal resistance a
> sufficient current limiter? I'm not familiar with super caps, but the
> common ones that I am familiar with will supply huge currents, momentarily.

The capacitor gets its voltage from the PV cell. Assuming that
you don't put a switch between the LED and the cap (there is none shown
in the schematic), the cap will never charge high enough to be able to
damage the LED, because the LED will have already clamped the maximum
voltage based on the current limit of the PV cell. Not sure what would
happen with the PV cell close to an arc welding process like a TIG -- it
depends on the internal resistance of the PV cell and the peak voltage
which the PV cell can produce with such excessive illumination.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: <BPdnicholsBP@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

== 3 of 4 ==
Date: Thurs, Nov 24 2011 9:46 pm
From: Jeff Liebermann

On Thu, 24 Nov 2011 18:13:15 -0800 (PST), dagmargoodboat@yahoo.com
wrote:

I found this, which calculates and measures caliper battery life:
<http://www.davehylands.com/Machinist/Caliper-Batteries/>

>Small, cheap and simple are the main factors here. The r.c.m. guys
>aren't going to be building switching regulators, and switching
>regulators generally aren't more efficient at these power levels
>anyhow--their quiescent current draw's too high.

True. However, switching regulators usually have some manner of load
shedding when the supply voltage is insufficient. Below that
threshold, the current drain is usually in nanoamps.

>(I've made a study of designing microwatt switchers, from scratch.
>It's possible, but wholly inappropriate here.)

You're ahead of me. I've never designed anything in that low power
class. Different world. Can you point me to a suitable (or close to
suitable) regulator chip?

>Not so fast... The advantage of the thin-film PV panels is that
>(appropriate) panels excel at producing power even in dim light.
>Polycrystalline silicon panels don't.
>The array I suggested for experimentation is thin-film for that
>reason--so it can work in indoor light levels.

Decisions, decisions, and more decisions. Polycrystaline has a cost
advantage and is more efficient than single layer thin-film. Well, if
I wanted to go cheap, I would use amorphous cells and mold them into
the plastic case. For small solar cells, the cost of monocrystaline
isn't all that much more (i.e. most of the cost is in packaging and
handling) but won't work well with indoor lighting. So, I guess
thin-film is the least disgusting.
<http://en.wikipedia.org/wiki/Solar_powered_calculator>
"Solar calculators may not work well in indoor
conditions under ambient lighting as sufficient lighting
is not available."

>> The next question is for how long will it run? Assuming the calipers
>> can handle 3.0VDC without damage, how long will a junk 100UF
>> electrolytic cap run the calipers?
>
>a) How long will it run? Not nearly long enough, and b) 3.0VDC is
>waayyy too risky for my blood. 20uA will discharge 100uF from 2.0V to
>1.35V in 3.25 seconds.

I used 1000uF elsewhere in my calcs, but slipped here and used 100uF
instead. Sorry.

I think you might be a bit too conservative. 5ua leakage is high.
Most of the spec sheets I've skimmed show 1-2ua for a typical 1F 5.5V
super-cap.

>Of the setup I suggested, the most marginal part is the itty bitty PV
>panel (its output is on the low side). Dark leakage on my much-larger
>10x55mm calculator panel is about 8uA @ 1.7V bias.

The alternative is to lose approximately 0.3V in a series Schottky
diode. That's about 20% of the power budget, which is probably too
much.

>The supercap works wonderfully well. Charge 0.6F to 1.8V, and you've
>got 4 hours' runtime until you reach the 1.35V battery-low display-
>starts-blinking level. (Assuming 20uA total draw, to allow for some
>leakage.)

Ok. You've sold me. I was trying to see what could be done with
commodity electrolytic caps. Also, super-caps fail to appreciate high
humidity, which may become a problem.

>> <http://www.kpsec.freeuk.com/capacit.htm>
>> From 1.37V is roughly 50% of full 3.0VDC charge. That's about 80% of
>> 1RC time constant. 1RC is:
>> 0.8 * 100K * 1000uF = 80 seconds
>> That's probably enough to make a few measurements. Any longer and a
>> super-cap will probably be needed. Picking 50% of full charge out of
>> the hat is rather convenient, as it makes the time to charge from zero
>> to the dropout point the same 80 seconds (yes, I'm lazy). Whether the
>> user really wants to wait 1.5 minutes under a desk lamp for the
>> calipers to be usable is dubious. Of course, a longer run time, means
>> a longer charge time. For example, a 1F 5V 1ua leakage super-cap,
>> will run the calipers for 80,000 seconds, but will also take 80,000
>> seconds to charge.
>
>Not 80,000s. Expose the PV to sunlight (or directly to a lamp), and
>it'll charge (initially) >50x faster. You'd only have to do that
>once. Indoors, the PV would keep it topped off, that's the idea.

Yep. However, I screwed up. The discharge load is:
1.5VDC / 15uA = 100K ohms
However, the charging ESR is much less.
3.0VDC / 2ma = 1.5K
It will certainly be higher a lower illumination levels. Checking my
junk cell under random room lighting conditions, and again scaling for
size, I get:
0.333 * 0.55v / 0.02mA = 9.2K
I don't have a small thin film panel to test. (I have 90watt panel,
but that's a bit much for scaling to caliper size).

>Alternatively, an electrolytic works, but gives a caliper that quickly
>quits if you accidentally shadow it.

Not if you do exactly like it's done with a calculator. When the cell
is shaded, it runs on battery. A silver-oxide battery holds:
1.5v * 150 mA-Hr = 22.5 milliwatt-Hrs
and will deliver most of that before the voltage drops to unusable
levels.

The super cap will deliver (very roughly):
1.5v * 15uA * 4Hr = 90 microwatt-Hrs

>There are much smaller supercaps--0.02F--used in cellphones. That's
>another option / compromise. Leakage should be better too.

Overview of CDE super-caps:
<http://www.cde.com/catalogs/EDL.pdf>
Some interesting notes on charge time and lifetime near the bottom.

>> In my never humble opinion, what makes more sense is to do it exactly
>> like the typical solar powered calculator. They all have one or two
>> LR44 batteries inside. However, the solar cell does NOT charge the
>> battery. When you turn the calculator on, and there's enough light to
>> run from the solar cell, the battery is essentially disconnected. When
>> there's not enough light to run the calculator, it runs off the
>> battery. No waiting to charge a capacitor from the solar cell.
>
>That uses the PV as, basically, a battery-extender. That's fine, but
>complex--you need a micro-power switch to disconnect the battery, etc.
>(A diode drops waayyy too much voltage.) That puts it out of the
>realm of a simple project that can fit into the existing caliper.

There has to be a chip in the calipers anyway to count pulses, run the
display, and deal with the push buttons. Adding a power management
feature does not add much real estate or complexity. However, if
you're thinking of a retrofit, I suspect something could be done with
a separate switcher chip.

>> If you're into high tech, there are various energy scavenging devices
>> that can also power the calipers.
>> <http://en.wikipedia.org/wiki/Energy_harvesting>
>> With only 22.5 microwatts required, it might be possible to power the
>> device with a wind up key, piezo pressure, body heat, kinetic magnetic
>> generator, etc. I kinda like the idea of a wind up caliper.
>
>Windup would be fun--steampunk.

In the late 1960's, I designed and built a paging receiver, that
produced the message output on a 1/4" wide roll of paper tape. Battery
power to the mechanics for such a portable device was impossible. So,
I went to a wind up coil spring mechanism. I've been somewhat of a
fan of spring power ever since.

>The "real" solution is to design the caliper to draw less current in
>the first place, like Mitutoyo and Starrett. If you've done that,
>solar-powering is a snap, but then, if the battery lasts years, you
>don't need solar power, do you?

Agreed. It would be like a digital watch, which typically has a 10
year battery life. However, the solar cell is still a problem because
of the dark current (reverse leakage). An isolating Schottky diode
can reduce that, but then the solar cell would need to be about 20%
larger to compensate for the added loss.

Another problem is that it would be no fun. Windup calipers offer a
far more entertaining problem to solve.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 4 of 4 ==
Date: Thurs, Nov 24 2011 10:29 pm
From: Jeff Liebermann

On Thu, 24 Nov 2011 21:46:48 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>>> The next question is for how long will it run? Assuming the calipers
>>> can handle 3.0VDC without damage, how long will a junk 100UF
>>> electrolytic cap run the calipers?
>>
>>a) How long will it run? Not nearly long enough, and b) 3.0VDC is
>>waayyy too risky for my blood. 20uA will discharge 100uF from 2.0V to
>>1.35V in 3.25 seconds.

Trying the same calc using the super-cap formula from Pg 6 of:
<http://www.cde.com/catalogs/EDL.pdf>

t = C delta V / I
t = C[V0-(i*R)-V1] / (i+iL)
where:
t: Back-up time (sec)
C: Capacitance of Type EDL (Farads)
V0: Applied voltage (Volts)
V1: Cut-off voltage (Volts)
i: Current during back-up (Amps)
iL: Leakage current (Amps)
R: Internal resistance (ohms) at 1 kHz

For this example, I'll use a 0.1F (type F) 5.5V 100 ohm cap.
The low end of the tolerance range might drop this to 0.08F.
V0 = 2.0V, V1 = 1.4V, i = 15uA, iL = 2uA

Plugging in:
t = C[V0-(i*R)-V1] / (i+iL)
t = 0.08F[2.0V-(15uA*100ohms)-1.4V]/(15uA+2uA)
t = 2800 sec = 47 minutes.
Not bad.

I guess the protective case that most calipers use will need a clear
plastic window to keep it charged. Maybe another window on top of my
toolbox.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

==============================================================================
TOPIC: Editing a pdf file ...
http://groups.google.com/group/sci.electronics.repair/t/e7a871e294322579?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Nov 24 2011 8:02 pm
From: Mike Tomlinson

En el artículo <kbDyq.13007$%K3.12035@newsfe01.ams2>, Arfa Daily
<arfa.daily@ntlworld.com> escribió:

>I've actually now managed to do the basic thing that I wanted. I ended up
>very carefully zooming the image (that was hard to do precisely, as the zoom
>bar wanted to 'snap' in 25% increments

There are a couple of good alternative PDF readers. I use Foxit Reader,
which allows you to set a zoom down to three decimal places. Free.

>Some jobs are
>just too difficult, frustrating and time consuming to do on a computer

Amen to that :-)

--
(\_/)
(='.'=)
(")_(")

== 2 of 2 ==
Date: Thurs, Nov 24 2011 9:54 pm
From: Jeff Liebermann

On Tue, 22 Nov 2011 01:47:58 -0000, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

>I've actually now managed to do the basic thing that I wanted. I ended up
>very carefully zooming the image (that was hard to do precisely, as the zoom
>bar wanted to 'snap' in 25% increments and didn't allow actual values to be
>typed in) until the bits that I didn't want were off the top and bottom of
>the screen, and the bit that I did want was centred. I then did a "print"
>and then "current view". Finally, I used the "Tile large sheets" option with
>the 'composite view' selected, and then used the print zoom to find the
>point where it just jumped up to two pages, and left an even border around
>the edge.

Reading between the lines, it appears that all you need is an
efficient way of extracting a JPG out of a PDF file. No big deal:
<http://www.tracker-software.com/product/pdf-xchange-viewer>
The PDF-Xchange Viewer includes a *free* PDF to JPG converter. I'm
usually lazy and just convert the entire document, which extracts a
large number of JPG's, most of which I discard. There are other PDF
to JPG converters, but this is the only free one that I found which
actually worked.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 1 of 1 ==
Date: Thurs, Nov 24 2011 11:59 pm
From: ritesh

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sci.electronics.repair - 3 new messages in 1 topic - digest

12:31 AM Penedão 0 comments

sci.electronics.repair
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Today's topics:

* Simple tone control? - 3 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/eb3fafaa60fb8246?hl=en

== 1 of 3 ==
Date: Mon, Nov 21 2011 10:07 pm
From: "Phil Allison"

"Jeffrey Angus"

> You're links are broken/segmented.
> <http://www.harmankardon.com/EN-US/Products/Pages/ProductDetails.aspx?PID=SOUNDSTICKS3AM>
> Does work...

** Not from outside the USA it don't.

And the UK one is the same.

How boring of them.

... Phil

== 2 of 3 ==
Date: Mon, Nov 21 2011 10:22 pm
From: Jeffrey Angus

On 11/22/2011 12:07 AM, Phil Allison wrote:
> "Jeffrey Angus"
>
>> You're links are broken/segmented.
>> <http://www.harmankardon.com/EN-US/Products/Pages/ProductDetails.aspx?PID=SOUNDSTICKS3AM>
>> Does work...
>
>
> ** Not from outside the USA it don't.
>
> And the UK one is the same.

Well that sucks, what's the point of that?

Jeff-1.0

--
"Everything from Crackers to Coffins"

== 3 of 3 ==
Date: Mon, Nov 21 2011 10:31 pm
From: spam@spam.com (Don Pearce)

On Tue, 22 Nov 2011 00:22:29 -0600, Jeffrey Angus <grendelair@aim.com>
wrote:

>On 11/22/2011 12:07 AM, Phil Allison wrote:
>> "Jeffrey Angus"
>>
>>> You're links are broken/segmented.
>>> <http://www.harmankardon.com/EN-US/Products/Pages/ProductDetails.aspx?PID=SOUNDSTICKS3AM>
>>> Does work...
>>
>>
>> ** Not from outside the USA it don't.
>>
>> And the UK one is the same.
>
>Well that sucks, what's the point of that?
>
>Jeff-1.0

Just need a proxy within the USA - always useful to have one available
for every major country.

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