Beckmann Digital Multimeters
mcp6453
simply go out of business, or did someone buy them up? I really prefer those
meters, probably because I'm familiar with them. What's a compatible brand?
Fluke? What other brand would you consider? There is a lot of junk out there.
PenaL
It's harmful if Beckmann doesn't make the measuring instruments. I used
them a lot at the end of 1980. At least Fluke is still one of the best
and reliable trademarks on the measuring tools. As like Tektronix on the
oscilloscopes.
-Pentti
William Sommerwerck
ago. A quick Web search suggests that Beckman is no longer around.
Nothin' wrong with a Fluke -- though they're not cheap.
Scott Dorsey
Beckman is still around but they are out of the test equipment business and
only making medical instrumentation now.
There are plenty of good digital multimeters out there. The Fluke 77 is very
hard to beat; it has a lot of digits and they are all trustworthy.
For day to day use I am useing a B&K Toolkit 2720A. It has only 3.5 digits
and the last one is not really trustworthy, but it has an hFE tester, a
capacitance tester, and a crude frequency counter, all of which have turned
out to be really handy in the field.
I have even used the capacitance tester for finding the distance to a break
in cables and it was remarkably close.
It's certainly not built like a Fluke and it's not as accurate as a Fluke,
but a lot of the time that's not important.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Arny Krueger
news:87-dnZkvdpMoOvrQ...@giganews.com
Fluke is pricey, but probably the Gold Standard of the industry.
A lot of the far more inexpensive stuff is really pretty good, depending on
what you want to do with it.
For the past 3 years I've been using a Harbor Freight DVM that cost me $2.95
to check batteries for wireless SR equipment.
It has about 1% accuracy and is entirely suitable for the purpose, within
its obvious limits.
Its no Fluke, but for the price, absolutely no complaints.
I do have a Fluke 85 and it is really good. Takes a licking and still
outperforms anything near its price and size after more than a decade.
But you don't need that quality to do about 99% of everything.
William Sommerwerck
cleaning the zebra pads on the LCD.
MCM has good cables and surge suppressors. I haven't tried their test
equipment, but they have "decent-looking" DVMs starting at $13.50.
http://www.mcmelectronics.com/search.aspx?C=0000001244
One of the problems with inexpensive DVMs is that they are /not/
auto-ranging. This is a major convenience, but it adds to the cost. Another
useful feature is a beeper that warns you that the cables are plugged into
the current jacks when they /shouldn't/ be.
G
> Both my desk and my portable digital multimeters are Beckmann. Did the company
> simply go out of business, or did someone buy them up? I really prefer those
> meters, probably because I'm familiar with them. What's a compatible brand?
I use all kinds, and sometimes I need an analog meter, and sometimes
with HV.
One can get really used to a fine meter like the Fluke 189 in the
shop.
AC, DC AC+DC, logging, temperature, diodes, cap, etc..
Fluke was trying to make some new meter with probes that automatically
change settings.
The 189 does warn if the probes are in the wrong holes.
greg
hank alrich
Fluke has a lower cost line now. They're mostly grey instead of all
yellow. I bought one a few years ago at a Fry's in Austin TX and it has
been working well. I got the last one in stock, no box, etc., and paid
$67 and change for it.
--
shut up and play your guitar * http://hankalrich.com/
http://armadillomusicproductions.com/who'slistening.html
http://www.sonicbids.com/HankandShaidriAlrichwithDougHarman
Bill Graham
Here is a link to Beckmann . They may have been bought out, but there are
still a lot of Beckmann meters out there for sale.
http://www.industrialpartner.com/industrial-control-panel-meters/meters/beckman/
William Sommerwerck
>> Did the company simply go out of business, or did someone buy
>> them up? I really prefer those meters, probably because I'm familiar
>> with them. What's a compatible brand? Fluke? What other brand
>> would you consider? There is a lot of junk out there.
> Here is a link to Beckmann. They may have been bought out, but
> there are still a lot of Beckmann meters out there for sale.
>
http://www.industrialpartner.com/industrial-control-panel-meters/meters/beckman
I note that the DM78 is still available. It's their knockoff of the HP 270,
* a much-more elegant (but larger) unit. If you don't have one, you should
consider getting one. It's useful, if only because you don't have to worry
about the tip slipping when you look up to read the meter.
While we're talking... I have a Sony Discman with a digital tuner and the CD
controls/display in a "lozenge" about the size of your little finger. Why
doesn't someone make a bench DMM with a display and controls built into the
probe?
* I still have mine, but without the nicad battery pack, it's useless. It's
interesting to note that the HP 270 appeared only a decade (roughly) after
the NLS DVM.
Mike Rivers
> Why
> doesn't someone make a bench DMM with a display and controls built into the
> probe?
I remember such a probe, I'm pretty sure it was
Hewlett-Packard. Obviously they weren't very popular.
--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson
http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff
William Sommerwerck
>> a display and controls built into the probe?
> I remember such a probe, I'm pretty sure it was
> Hewlett-Packard. Obviously they weren't very popular.
Was it actually a bench meter? The HP-270 was a stand-alone (or should I say
carry-alone?) device.
I'd think they'd be very popular. You wouldn't have to look up at the meter,
or worry about the tip slipping.
Ron Capik
> On 2/26/2011 9:02 AM, William Sommerwerck wrote:
>
>> Why
>> doesn't someone make a bench DMM with a display and controls built
>> into the
>> probe?
>
> I remember such a probe, I'm pretty sure it was Hewlett-Packard.
> Obviously they weren't very popular.
>
>
the 167 Auto-probe DMM.
I seem to recall it being a little
clumsy to use.
I think I still have one somewhere
in my junk closet.
Later...
Ron Capik
--
William Sommerwerck
>>> and controls built into the probe?
>> I remember such a probe, I'm pretty sure it was Hewlett-Packard.
>> Obviously they weren't very popular.
That's the HP-270 -- the entire DMM was a fat, cordless "probe". I bought
one in 1973 and carried it with me when I worked for Bendix. Saved my ass on
a few occasions. I'd still be using it had HP continue to manufacture
reasonably-priced battery packs. It does work on 9V. Perhaps someday I'll
rewire to use a 9V battery.
> Keithley made one in 1972, the 167 Auto-probe DMM.
This is what I was referring to -- a bench DMM with a probe that included a
second display. I still think it's a great idea. (After seeing the photo, I
remember it.)
> I seem to recall it being a little clumsy to use.
If it had been made by HP, it probably would have been a bit more elegant.
The problem, of course, is that the display is at the far end of the probe,
throwing off the balance.
> I think I still have one somewhere in my junk closet.
If it's in working order... How much would you like?
Roy W. Rising
> On 2/26/2011 9:02 AM, William Sommerwerck wrote:
>
> > Why
> > doesn't someone make a bench DMM with a display and controls built into
> > the probe?
>
> I remember such a probe, I'm pretty sure it was
> Hewlett-Packard. Obviously they weren't very popular.
I have a Beckman Circuitmate DM73 Probemeter. Small, convenient, not too
versatile. Here's a link for the successor DM73B:
http://www.gearmonkey.tv/shop/beckman-digital-multimeter-dm73b-p-54-c-5_11.
html
--
~ Roy
"If you notice the sound, it's wrong!"
William Sommerwerck
Ditto.
> Small, convenient, not too versatile. Here's a link for the successor
DM73B:
http://www.gearmonkey.tv/shop/beckman-digital-multimeter-dm73b-p-54-c-5_11.html
It appears to be the same product, but with minor cosmetic and ergonomic
improvements.
Bill Graham
> On 2/26/2011 9:02 AM, William Sommerwerck wrote:
>
>> Why
>> doesn't someone make a bench DMM with a display and controls built
>> into the probe?
>
> I remember such a probe, I'm pretty sure it was
> Hewlett-Packard. Obviously they weren't very popular.
Yes. HP came out with them first, but soon there were several others on the
market. The HP's were pretty nice, because you coulde get the display to
show upside down at the press of a button so you could read it in unusual
positions, like if you were checking voltages in racks over your head. They
still required a long ground wire with a clip on the end, so in reality,
they weren't that much better than a standart multimeter.....
Mike Rivers
> The HP's [multimeter in a probe] were pretty nice,
> because you coulde get the display to show upside down at
> the press of a button so you could read it in unusual
> positions, like if you were checking voltages in racks over
> your head. They still required a long ground wire with a
> clip on the end, so in reality, they weren't that much
> better than a standart multimeter.....
Well, what multimeter can measure voltage without a
connection to a reference point?
Bill Graham
> On 2/26/2011 7:44 PM, Bill Graham wrote:
>
>> The HP's [multimeter in a probe] were pretty nice,
>> because you coulde get the display to show upside down at
>> the press of a button so you could read it in unusual
>> positions, like if you were checking voltages in racks over
>> your head. They still required a long ground wire with a
>> clip on the end, so in reality, they weren't that much
>> better than a standart multimeter.....
>
> Well, what multimeter can measure voltage without a
> connection to a reference point?
None, of course. And that's one reason why the "pencil meters" didn't go
over very well. Other cheaper meters, that were small and light weight were
just as useful. The pencil meters couldn't really be carried in your shirt
pocket with a six foot ground wire attached.......
Scott Dorsey
>On 2/26/2011 7:44 PM, Bill Graham wrote:
>
>> The HP's [multimeter in a probe] were pretty nice,
>> because you coulde get the display to show upside down at
>> the press of a button so you could read it in unusual
>> positions, like if you were checking voltages in racks over
>> your head. They still required a long ground wire with a
>> clip on the end, so in reality, they weren't that much
>> better than a standart multimeter.....
>
>Well, what multimeter can measure voltage without a
>connection to a reference point?
Now we are seeing tweezer multimeters, for measuring between two points on
SMT chips. They work pretty well for that, really.
Shaun
Wavetek bought the digital multimeter portion of Beckman, then Amprobe /
Meterman took it over. Look up HD110c DMM on Google. or click on this
link.
http://www.hmcelectronics.com/cgi-bin/scripts/product/HD110/Amprobe-HD110
The meter has a larger display than the original Beckman and the case has
been changed a little. Same color and same ranges as the original Beckman.
BTW: I used to fix Beckman meters 12 to 16 years ago.
Shaun
Ed Kenny
I have a Beckman Tech 310 that's probably from the late '70s or early
'80s and I still use it and love it. What a beautiful meter. I use
various meters in my job, but when I have real serious troubleshooting to
do, I bring in my old Beckman. I'm really going to miss it when it's gone.
hank alrich
> I'd still be using it had HP continue to manufacture
> reasonably-priced battery packs.
I have an HP calculator of which I say the same.
William Sommerwerck
>>> display and controls built into the probe?
>> I remember such a probe [multimeter], I'm pretty sure it
>> was Hewlett-Packard. Obviously they weren't very popular.
> Yes. HP came out with them first, but soon there were several
> others on the market. The HP's were pretty nice, because you
> could get the display to show upside down at the press of a
> button so you could read it in unusual positions, like if you were
> checking voltages in racks over your head. They still required a
> long ground wire with a clip on the end, so in reality, they weren't
> that much better than a standard multimeter...
Well, they had no power cord!
I remember having to take a reading at a NASA station that required me to
stretch the coiled ground lead several feet! It took a few days for it to
return to normal.
Mike Rivers
> William Sommerwerck<grizzle...@comcast.net> wrote:
>> I'd still be using it had HP continue to manufacture
>> reasonably-priced battery packs.
> I have an HP calculator of which I say the same.
I've made several new battery packs for my HP-55. It's still
ticking. I'm one of the few people, I guess, to which
Reverse Polish made sense.
Mike Rivers
>>>> Why doesn't someone make a bench DMM with a
>>>> display and controls built into the probe?
> I remember having to take a reading at a NASA station that required me to
> stretch the coiled ground lead several feet! It took a few days for it to
> return to normal.
This is why they make clip leads. <g> I don't care for
coiled cords on anything and I was happy to see that at
least one headphone manufacturer made a non-coiled
replacement cord (or maybe it was even an option with a new
purchase).
William Sommerwerck
> I've made several new battery packs for my HP-55. It's
> still ticking. I'm one of the few people, I guess, to which
> Reverse Polish made sense.
I'd never heard of it until I bought the HP-35. It made /immediate/ sense.
Anyone who's used an RPN calculator would never go back to algebraic for
on-the-fly calculations.
I solve my HP-41X because I needed the money. I still have the HP-28S, which
is quite nice.
hank alrich
> On 2/27/2011 12:40 AM, hank alrich wrote:
> > William Sommerwerck<grizzle...@comcast.net> wrote:
>
> >> I'd still be using it had HP continue to manufacture
> >> reasonably-priced battery packs.
>
> > I have an HP calculator of which I say the same.
>
> I've made several new battery packs for my HP-55. It's still
> ticking. I'm one of the few people, I guess, to which
> Reverse Polish made sense.
Ditto. I'll have to check the model # and get back to you. <g>
Scott Dorsey
>William Sommerwerck <grizzle...@comcast.net> wrote:
>
>> I'd still be using it had HP continue to manufacture
>> reasonably-priced battery packs.
>
>I have an HP calculator of which I say the same.
All of the old HP calculator battery packs are just NiCD AA cells in funny
plastic packages. You can recell them yourself for a few bucks, or have a
place that does battery rebuilding do it for you.
Or you can buy third-party replacements from International Calculator in
florida.
mcp6453
Scott comes through again! These guys have a battery for my HP-45 for $39. And I
thought it was a museum piece.
Ron Capik
I also totally love RPN calculators.
I never had any of the first generation machines.
The buttons stopped working on my HP-25 ages ago.
I do have a HP-10c that I still use regularly.
I also have a HP-32s somewhere that needs batteries.
Later...
Ron Capik
--
Scott Dorsey
>> Or you can buy third-party replacements from International Calculator in
>> florida.
>
>thought it was a museum piece.
They did a rebuild on the HP34C that I bought in college and... it might be
a museum piece but it gets used regularly.
Ron Capik
parts. The bottom cover and power pack
are lost or misplaced.
Later...
Ron Capik
--
Bill Graham
True... they sure beat the hell out of those old black Simpsons that I was
raised to believe were the only meters in town. They were as big as houses
and weighed about 5 pounds!
Bill Graham
> On 2/27/2011 12:40 AM, hank alrich wrote:
>> William Sommerwerck<grizzle...@comcast.net> wrote:
>
>>> I'd still be using it had HP continue to manufacture
>>> reasonably-priced battery packs.
>
>> I have an HP calculator of which I say the same.
>
> I've made several new battery packs for my HP-55. It's still
> ticking. I'm one of the few people, I guess, to which
> Reverse Polish made sense.
I still use my HP 15C. One of the best pocket calculators ever made.
Bill Graham
> On 2/27/2011 6:24 AM, William Sommerwerck wrote:
>>>>> Why doesn't someone make a bench DMM with a
>>>>> display and controls built into the probe?
>
>> I remember having to take a reading at a NASA station that required
>> me to stretch the coiled ground lead several feet! It took a few
>> days for it to return to normal.
>
> This is why they make clip leads. <g> I don't care for
> coiled cords on anything and I was happy to see that at
> least one headphone manufacturer made a non-coiled
> replacement cord (or maybe it was even an option with a new
> purchase).
Cords, in general are the bane of the technical person. Every piece of
equipment I have has a rats nest of wires behind it, and with my failing
vision, it is increasingly harder for me to work with any of that stuff. You
should see the back of my computer desk.... Unbelievable! I think there is a
family of mice living back there.... Even my cats are afraid to go
there.....
Scott Dorsey
>
>True... they sure beat the hell out of those old black Simpsons that I was
>raised to believe were the only meters in town. They were as big as houses
>and weighed about 5 pounds!
I keep a Simpson 260 on the bench, because it's still a handy thing to have
for looking at time-varying signals. Put it on ohms function and bridge it
across a cap and you can calculate the cap value from the time constant as
it charges. Also very handy _because_ it is low impedance compared with a
DMM; sometimes poor connections will pass enough current to show up on the
DMM but not actually enough to provide useful current or move the meter in
the Simpson.
PStamler
algebraic calc. (from Sharp) and never looked back. Some functions
(like log and square root) are RPN, while the basic arithmetical
functions are algebraic. The combination works really well.
Peace,
Paul
Mike Rivers
> Cords, in general are the bane of the technical person.
> Every piece of equipment I have has a rats nest of wires
> behind it, and with my failing vision, it is increasingly
> harder for me to work with any of that stuff. You should see
> the back of my computer desk....
There are actually some pretty decent cable management
parts. Unfortunately they're not as cheap as they look like
they should be. I have a few pieces of Panduct
(http://tinyurl.com/panduct) on the back of my rack and desk
that keeps cable runs neat. With the slotted walls, it's
easy to break a cable out of the bunch wherever it's needed,
and the slide-off cover makes it easy to add, remove, or
move a wire in a run.
William Sommerwerck
That is exactly the argument used /against/ such calculators.
If you are trying to perform calculations ad hoc, RPN is the only way to go.
Algebraic notation works well when you are entering a formula that will
become part of a program.
William Sommerwerck
> Every piece of equipment I have has a rats nest of wires
> behind it, and with my failing vision, it is increasingly
> harder for me to work with any of that stuff. You should
> see the back of my computer desk.... Unbelievable! I think
> are afraid to go there...
I wish there /were/ mice back there -- I'm a murinophile of long standing.
You're hardly unique. Unless and until someone comes up with a short-range
wireless system that works with /every/ computer component, the rat's nest
will continue.
About 40 years ago, the cover of "Stereophile" showed the back of a fairly
simple stereo system -- it was an appalling tangle of wires. My current
system uses three dbx 400X switchers (Front, Side, Rear) to control both
input selection and all the analog "heritage" equipment my pre-con doesn't
support. I should have sent JGH a photo while he was alive -- but it
probably would have killed him.
William Sommerwerck
> parts. Unfortunately they're not as cheap as they look like
> they should be. I have a few pieces of Panduct
> (http://tinyurl.com/panduct) on the back of my rack and desk
> that keeps cable runs neat. With the slotted walls, it's
> easy to break a cable out of the bunch wherever it's needed,
> and the slide-off cover makes it easy to add, remove, or
> move a wire in a run.
My computer desk has a cable tray at the rear. But that doesn't take care of
all the stuff that /isn't/ on my desk. And by the time the cables reach the
computer...
I think I see a solution, but it's not simple. Perhaps, someday, when I have
nothing else to do...
Les Cargill
>> Cords, in general are the bane of the technical person.
>> Every piece of equipment I have has a rats nest of wires
>> behind it, and with my failing vision, it is increasingly
>> harder for me to work with any of that stuff. You should
>> see the back of my computer desk.... Unbelievable! I think
>> there is a family of mice living back there... Even my cats
>> are afraid to go there...
>
> I wish there /were/ mice back there -- I'm a murinophile of long standing.
>
> You're hardly unique. Unless and until someone comes up with a short-range
> wireless system that works with /every/ computer component, the rat's nest
> will continue.
>
Bluetooth can do just about everything but your LAN cable, and
maybe even that. Of course,then 2.4GHz gets crowded.
> About 40 years ago, the cover of "Stereophile" showed the back of a fairly
> simple stereo system -- it was an appalling tangle of wires. My current
> system uses three dbx 400X switchers (Front, Side, Rear) to control both
> input selection and all the analog "heritage" equipment my pre-con doesn't
> support. I should have sent JGH a photo while he was alive -- but it
> probably would have killed him.
>
>
--
Les Cargill
Bill Graham
> On 2/27/2011 7:18 PM, Bill Graham wrote:
>
>> Cords, in general are the bane of the technical person.
>> Every piece of equipment I have has a rats nest of wires
>> behind it, and with my failing vision, it is increasingly
>> harder for me to work with any of that stuff. You should see
>> the back of my computer desk....
>
> There are actually some pretty decent cable management
> parts. Unfortunately they're not as cheap as they look like
> they should be. I have a few pieces of Panduct
> (http://tinyurl.com/panduct) on the back of my rack and desk
> that keeps cable runs neat. With the slotted walls, it's
> easy to break a cable out of the bunch wherever it's needed,
> and the slide-off cover makes it easy to add, remove, or
> move a wire in a run.
Well, I have to admit that I haven't spent much time/effort trying to clean
up my rat's nests.... For starters, I screwed a 12 plug AC strip to the
back of my desk, and fed it with a regulated line conditioner, but I didn't
shorten any of the lines that it feeds, so there are wires everywhere. Part
of the reason was I wasn't sure whether I was going to like where I put all
the units they fed, and it was kind of a good thing I didn't cut the wires,
because I have repositioned some of the stuff and fortunately, it wasn't
locked into any fixed position. But now, I think I could shorten some of the
wires.....Maybe I'll just fold them up and tie wrap them..... I used to work
in a shop where they hung AC line cords from the ceiling, and that was
pretty handy, even if it looked like hell...... And then, there are all the
USB cables.....
Bill Graham
Well, I had an idea once in my stereo hi-fi system, to build a patch panel,
and mount it at the front of the system somewhere where it would be easy to
get to. and then, run the inputs and outputs of every chassis I had to the
rear of the panel, so all interconnections could be made with short patch
cords at the front. This way, changes in the set up could be made without
having to mess with all the wires coming to and from each unit. A lot of
work to be sure, but it could save a lot of time if you made frequent
changes to your set up.
George's Pro Sound Company
"Bill Graham" <we...@comcast.net> wrote in message
news:R5CdnRPKov1_2e3Q...@giganews.com...
mount case as double sided rca connectors, just drill the holes use 6 inch
rca to rca inside the rack case and little one foot rca to rca jumpers for
the front panel
really only took maybe 60$ in parts and two or three hours time ,as I
avioded all the soldering and cable prep
George
George's Pro Sound Company
press and hand drill is unsuitable for this job) use 6 inch
George's Pro Sound Company
William Sommerwerck
> panel, and mount it at the front of the system somewhere where it
> would be easy to
> get to. and then, run the inputs and outputs of every chassis I had to the
> rear of the panel, so all interconnections could be made with short patch
> cords at the front. This way, changes in the set up could be made without
> having to mess with all the wires coming to and from each unit. A lot of
> work to be sure, but it could save a lot of time if you made frequent
> changes to your set up.
Russound used to make a mini patch panel. I still have it, though I don't
use it any more.
My current system uses three dbx 400X switchers, to control the front, side,
and rear signals, including a variety of decoders and signal processors.
Bill Graham
Well, I was going to use a variety of connectors, depending on whether I was
routing TV signals or audio, or high current speaker cables, but I never got
around to actually building it. It joined the, "projects lost" group.......
(a group that is getting larger and larger as I grow older and older)
Bill Graham
Well, I had a situation where there were teenagers changing my setup
frequently, so I needed a way of restoring it quickly. But today, all the
teenagers are gone to schools and the like in other states, so I don't
really have the problem anymore.
Hank
My "Simpson meter" is a Triplett 630-NA. These were the "standard
issue" when I worked at Tektronix in the 1960's. Bigger (1/2 inch in
all dimensions) and heavier (5 lbs rather than 3) than the Simpson
260, but a much nicer setup than the Simpson. Big plus was the V-A/2
feature which doubled sensitivity. Twice the price of a 260, but well
worth it. I looked for one for a couple of years at hamfests, etc.,
but all I saw were beat-up 260's; so took the plunge and bought a new
one. Sad to say, they're NLA from Triplett, and the current
plain-jane 630 is not at all comparable.
Working with analog, the pointer movement tells half the tale. It's a
good low-freqency scope---oftentimes what the pointer settles on is
secondary, because I didn't like the way it moved. Plus, I can see the
motion with peripheral vision rather than having to look away to
comprehend numbers, even if they do settle down to a stable
indication.
As you've pointed out, the RX1 range on analog meters passes a fairly
hefty current (about 350 ma.) through the probes, so a poor connection
in an automotive circuit is pretty obvious. However, with automotive
testing, I generally look for voltage drops in the malfunctioning
circuit (following Kirchoff's voltage law). Few mechanics, who may be
good at engines and transmissions, know much about how to chase
electrical problems.
Hank
Scott Dorsey
>
>As you've pointed out, the RX1 range on analog meters passes a fairly
>hefty current (about 350 ma.) through the probes, so a poor connection
>in an automotive circuit is pretty obvious. However, with automotive
>testing, I generally look for voltage drops in the malfunctioning
>circuit (following Kirchoff's voltage law). Few mechanics, who may be
>good at engines and transmissions, know much about how to chase
>electrical problems.
I seem to spend a lot of my time finding problems in antenna systems, and
it's good for that as well, for the same reasons.
Bill Graham
Yes. My Subaru battery was running down. If I didn't drive the car for about
three days, it would be too dead to start it. I brought it in for service,
and the mechanic said, "We couldn't find anything wrong with the battery".
Of course not, I was thinking. It isn't the battery, but something in the
car that's running it down, but I said nothing. Then, we took a trip to my
daughter's house in Thayne, Wyoming, about 1500 miles away. I brought my
slides, projecter, and screen with us. The screen was 8 feet long, so I had
to remove the section in the rear seat that gave me entrance to the trunk in
order to hold it in the trunk. When we arrived in Wyoming a couple of days
later, it was after dark, and my son-in-law said, "The light in your trunk
is on, Bill". I knew immediately why my battery was running down. Someone,
(probably me) had slammed the trunk lid closed too hard, and scattered the
light switch. But you are right. Auto mechanics in general know little about
electrics in the cars they service.