Turn Your Power Supply into an Ohmmeter - It's Free!

[Watson A.Name - 'Watt Sun]

In article <2pIRa.22340$n95.2177507@news4.srv.hcvlny.cv.net>,
178048316@icq.net mentioned...

When I need to power some of my smaller creations I use an ohmmeter as a
power supply...

Must be _very_ low power!


--
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Just when you thought you had all this figured out, the gov't
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@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Watson A.Name - 'Watt Sun]

In article <zHGRa.76969$wk6.18273@rwcrnsc52.ops.asp.att.net>,
Watchit@Comcast.net mentioned...

"Tim Williams" <tmoranwms@charter.net> wrote in message
news:vhe6u95nd8l13d@corp.supernews.com...
"Ratch" <Watchit@Comcast.net> wrote in message
news:BZmRa.80118$Ph3.9181@sccrnsc04...
While correct and true in all
cases, those formulas are NOT Ohm's law, and it is wrong to call them
that.

Dude, go back to school, Algebra 1. V=IR > I=V/R > R=V/I etc.
The equation can be rearranged to any of the others by simple
multiplication and division by whichever variable.

Tim

I believe everyone on this newsgroup can isolate each of the terms
algebraically. What is your point? What don't you agree with? What is
incorrect? Be specific. Ratch

I think the point of everyone here is that you're being pedantic,
pointing out something that has no real relation to the topic being
discussed.


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

 

[Watson A.Name - 'Watt Sun]

In article <UaLRa.107281$Io.9166554@newsread2.prod.itd.earthlink.net>,
mcmcm@earthlink.net mentioned...

After all that I still can't get my ohmmeter to work as a power supply!!!

Tsk-tsk! Siwwy wabbit! You have to unscrew the back of the meter,
and remove the 9V battery, then connect the wires to it! Simple!

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

 

[Watson A.Name - 'Watt Sun]

In article <3F177511.43D62E8C@bellatlantic.net>,
ehsjr@bellatlantic.net mentioned...

Tim Williams wrote:


Tim (can't believe the number of negative replies on this thread)

Exactly. It is un-eff-ing believable how some people just love
to snipe.

I wonder how many of the "snipers" ever had to brew a meter shunt?
You can use the "Watson ohmmeter" for that - and, as another
poster mentioned - toss your Fluke in the dustbin.

Hey, I like that.. It has a nice ring to it: "Watson Ohmmeter".

One of the maintenance guys at work gave me a Fluke 23 meter which is
just a yellow cased version of the 73, I believe. Said he sent it to
Fluke but they sent it back because it it was beyond repair or it
would cost more than a new meter. He might have done something really
stoopid like set it to the ohms range and put it on the 480VAC. In
any case, the display comes on, but nothing happens when the test
leads are connected to a V source. Apparently something major has
been zapped. It's been laying around at work for a couple years, it
probably oughtta be tossed in the trash can. The case is kind of
grubby so it's not worth saving for the case. Maybe I should give it
to the theater dept to use as a prop.

Recently the theater guy came over and asked our help desk lady for a
dozen telephone handsets and curly cords. She asked him what they
were going to do with them. He said they were going to use them as
props in a play, the actors would be dancing around with the handset
and the curly cord on stage. He said they would give them back after
the play was over.

Maybe they were going to imitate that Sprint guy: "Can you hear me
now?"...


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

 

[Ratch]

"Ratch" <Watchit@Comcast.net> wrote in message
news:BZmRa.80118$Ph3.9181@sccrnsc04...
While correct and true in all
cases, those formulas are NOT Ohm's law, and it is wrong to call
them
that.

Dude, go back to school, Algebra 1. V=IR > I=V/R > R=V/I etc.
The equation can be rearranged to any of the others by simple
multiplication and division by whichever variable.

Tim

I believe everyone on this newsgroup can isolate each of the terms
algebraically. What is your point? What don't you agree with? What is
incorrect? Be specific. Ratch

I think the point of everyone here is that you're being pedantic,
pointing out something that has no real relation to the topic being
discussed.

Good. You finally gave a valid reason for your gripe and did not deny

my "factoid". I can understand and appreciate your concern and irritation.
However, these threads are not just read and appreciated by you , I, and a
select few. There are plenty of lurkers who don't mind learning something,
and inserting ancillary facts into a discussion is not beyond what is
normally done here. Look at how some of the other threads have morphed.
Anyway, I don't think I was out of line in pointing out that Ohm's law is
usually used as a misnomer. The choice to keep on doing so is up to the
individual. Ratch

 

[Chuck Harris]

Hi Ratch,

It is not as simple as all that. E = Ri has been called "Ohm's" law for
as far back as my reference library goes, which is 1907. I cannot
verify, but I would presume that the origin of the the alleged misuse
goes even further back.

In any case, this relation has been called Ohm's law for so long, that
regardless of its origin, it *is* Ohm's law. To try and change the
common usage at this late date would just needlessly confuse the issue.

As a possible explanation for the term Ohm's law, consider that the unit
of resistivity has been called the ohm, as a tribute to Georges Ohm.

The equation that describes the relationship of resistance, voltage,
and current would naturally be called the law of resistance, or the
law of the ohm. It wouldn't take much to morph that to ohm's law.

-Chuck, WA3UQV

Good. You finally gave a valid reason for your gripe and did not deny
my "factoid". I can understand and appreciate your concern and irritation.
However, these threads are not just read and appreciated by you , I, and a
select few. There are plenty of lurkers who don't mind learning something,
and inserting ancillary facts into a discussion is not beyond what is
normally done here. Look at how some of the other threads have morphed.
Anyway, I don't think I was out of line in pointing out that Ohm's law is
usually used as a misnomer. The choice to keep on doing so is up to the
individual. Ratch

 

[ĺnřn˙mřu§]

On Fri, 18 Jul 2003 01:51:58 GMT, "Peter Gottlieb" <178048316@icq.net> wrote:

When I need to power some of my smaller creations I use an ohmmeter as a
power supply...
Hummm ... I have actually seen CMOS circuits run! With just test equipment attached and the power supply off!

 

[Mike Russell]

Chuck Harris wrote:

Hi Ratch,

It is not as simple as all that. E = Ri has been called "Ohm's" law
for
as far back as my reference library goes, which is 1907. I cannot
verify, but I would presume that the origin of the the alleged misuse
goes even further back.

A friend of mine took an electronics class at a local JC, and he learned
"Ohm's Three Laws": E=IR, I=E/R, and R = E/I.

--

Mike Russell
http://www.curvemeister.com
http://www.zocalo.net/~mgr
http://geigy.2y.net

 

[buck rojerz]

"Ratch" <Watchit@Comcast.net> wrote in
news:BZmRa.80118$Ph3.9181@sccrnsc04:

"Mark D. Zacharias" <mzacharias@nospam.earthlink.net> wrote in message
news:4BmRa.5630$Mc.475640@newsread1.prod.itd.earthlink.net...
Yes, and Ohm's Law describes the interaction of resistance, voltage,
and current. Not just resistance.
I'm not an engineer, granted, but I don't require an education on
Ohm's
Law.

Mark Z.

I belive that you are missing the point. The resistance (or
impedance)
formula V=IR (or V=IZ), describes the describes the interaction of
resistance (impedance), voltage, and current. While correct and true
in all cases, those formulas are NOT Ohm's law, and it is wrong to
call them that. As shown in the second link I gave, Ohm's law is a
property of resistive linearity in a material. Just as the specific
gravity of a material is a property. If it conforms to Ohm's law, it
is ohmic. Otherwise it is nonohmic. Ratch

What the heck is "nonohmic"? Is this a word you just made up? I have been
an electronis tech for 30+ years and thats a new one on me. It all doesn't
matter. Wether it is inductance, capacitive impedance, a thermistor, a
varistor, or what ever. Ohm's law still stands firm. For changing
"impedance" or fixed resistance. At any moment in time, there is a certain
resistance(impedance), a certain voltage and a certain current and ohm's
law always applies. Even in a combined circuit of capacitance and
inductance with an appplied frequency signal. At 1 instantaneous moment,
there is a vectored impedance and associated voltage and current. It is a
law of physics and there is no getting around it no matter what you call
it. A rose is a rose is a rose.
Here are the formulae and you believe what you will.

 

[Frank Bemelman]

"Chuck Harris" <cfharris@erols.com> schreef in bericht
news:bf9642$l2a$1@bob.news.rcn.net...

Hi Ratch,

It is not as simple as all that. E = Ri has been called "Ohm's" law for
as far back as my reference library goes, which is 1907. I cannot
verify, but I would presume that the origin of the the alleged misuse
goes even further back.

In any case, this relation has been called Ohm's law for so long, that
regardless of its origin, it *is* Ohm's law. To try and change the
common usage at this late date would just needlessly confuse the issue.

As a possible explanation for the term Ohm's law, consider that the unit
of resistivity has been called the ohm, as a tribute to Georges Ohm.

The equation that describes the relationship of resistance, voltage,
and current would naturally be called the law of resistance, or the
law of the ohm. It wouldn't take much to morph that to ohm's law.

Let's go all nuts and talk about ohmistance & ohmistors from now on

--
Thanks,
Frank Bemelman
(remove 'x' & .invalid when sending email)

 

[Ian Stirling]

In sci.electronics.misc Lizard Blizzard <NOSPAM@rsccd.org> wrote:

Ian Stirling wrote:
In sci.electronics.misc Watson A.Name - 'Watt Sun' <alondra101@hotmail.com> wrote:

In article <bf4ah6$a2p$3$8300dec7@news.demon.co.uk>,
root@mauve.demon.co.uk mentioned...

In sci.electronics.misc Watson A.Name - 'Watt Sun' <alondra101@hotmail.com> wrote:

I got tired of switching the leads of my DMM. Suddenly if dawned on
me that I can just set the power supply to 10.0V for exaample, and
read the current, and then divide the voltage by the current to find
the resistance. Like I put a resistance on the PS, it reads 10.0V and
the current is .018A, so 10 / .018 gives 555.6 ohms. Must be a 560
ohm resistor.

I turned my PS into an ohmmeter - FREE!

Hee-hee - Work smarter, not harder!

Of course, make sure the current stays low so the resistance doesn't
overheat. For low resistances use a volt or less.

This isn't especially usefull usually.
However, with low ohm resistors, it can be.

Given a constant current of an amp, the $5 meters mentioned elsewhere
can now measure with a resolution of .1mohm.

I bought a few of those $5 DMMs from Futurlec a few months ago,
actually I think they were about $6. 9V vattery included(!)


Very handy indeed.
The ones I bought were 3 pounds 99p, ($6us?) I have around 8.
Soon after buying one, I thought I'd discovered that they have an
overvoltage LED.
However, the smell of burning FR4 soon made me realise otherwise.

But, But.. Doesn't the FR in FR4 mean flame resistant? If so, how
could it burn? Char?

Hmm, probably, yes.
It went out when the source of 2000V (at moderate current) was turned off.

--
http://inquisitor.i.am/ | mailto:inquisitor@i.am | Ian Stirling.
---------------------------+-------------------------+--------------------------
Lord, grant me the serenity to accept that I cannot change, the
courage to change what I can, and the wisdom to hide the bodies
of those I had to kill because they pissed me off. - Random

 

[Watson A.Name - 'Watt Sun]

In article <bf9fdb$1jt$1$8302bc10@news.demon.co.uk>,
root@mauve.demon.co.uk mentioned...

In sci.electronics.misc Lizard Blizzard <NOSPAM@rsccd.org> wrote:
Ian Stirling wrote:
In sci.electronics.misc Watson A.Name - 'Watt Sun' <alondra101@hotmail.com> wrote:

In article <bf4ah6$a2p$3$8300dec7@news.demon.co.uk>,
root@mauve.demon.co.uk mentioned...

In sci.electronics.misc Watson A.Name - 'Watt Sun' <alondra101@hotmail.com> wrote:

I got tired of switching the leads of my DMM. Suddenly if dawned on
me that I can just set the power supply to 10.0V for exaample, and
read the current, and then divide the voltage by the current to find
the resistance. Like I put a resistance on the PS, it reads 10.0V and
the current is .018A, so 10 / .018 gives 555.6 ohms. Must be a 560
ohm resistor.

I turned my PS into an ohmmeter - FREE!

Hee-hee - Work smarter, not harder!

Of course, make sure the current stays low so the resistance doesn't
overheat. For low resistances use a volt or less.

This isn't especially usefull usually.
However, with low ohm resistors, it can be.

Given a constant current of an amp, the $5 meters mentioned elsewhere
can now measure with a resolution of .1mohm.

I bought a few of those $5 DMMs from Futurlec a few months ago,
actually I think they were about $6. 9V vattery included(!)


Very handy indeed.
The ones I bought were 3 pounds 99p, ($6us?) I have around 8.
Soon after buying one, I thought I'd discovered that they have an
overvoltage LED.
However, the smell of burning FR4 soon made me realise otherwise.

But, But.. Doesn't the FR in FR4 mean flame resistant? If so, how
could it burn? Char?

Hmm, probably, yes.
It went out when the source of 2000V (at moderate current) was turned off.

Eeww!! StinkCity!

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

 

[William Hayes]

Its one of those connie current things getting ronnie resistor ... hot.

"Sofie" <sofie@olypen.com> wrote in message
news:vhe7n8oe70ske4@corp.supernews.com...

How hot?
--------------
And besides that, it measures actual in-circuit conditions, because a
resistor is *supposed* to get hot, at least if it's doing its job...

 

[William Hayes]

"Sofie" <sofie@olypen.com> wrote in message
news:vheca77sefdtd5@corp.supernews.com...

Sir Charles W. Shults III:
That is a good in depth, overly complicated, answer but not the one I was
looking for

There was these two Engineers.... leaving the work place, they were headed
home.
They left the building headed out to the parking lot when the first engineer
stopped at a brand new 10 speed bike,
bent over and unlocked it. The second engineer looked at the first and
said, "Hey, I didn't know you got a new bike."
The first engineer started recounting his experience at getting the new
bike, "Yeah, I was out jogging my 1/2 block down the street when a lady on
this ten speed bike came by. She stopped. Got off the bike. Took all her
clothes off. Stood in front of me and said to me that I could have anything
I wanted." The second engineer thought for a moment and replied, " Yeah,
good choice, I don't think you'd fit into any girlie clothes, either."

So, now that we've had a nice discussion about ohm's law, explain that
fangled volt/amps rating on stuff.
I'm sure someone will note it is "nonohmic" somewhere...

 

[William Hayes]

"Mark Mcmillan" <mcmcm@earthlink.net> wrote in message
news:UaLRa.107281$Io.9166554@newsread2.prod.itd.earthlink.net...

After all that I still can't get my ohmmeter to work as a power supply!!!

Probably an analog meter multimeter.
You'll have to get with the program and buy a digital one.

 

[William Hayes]

"Mark Jones" <127.0.0.1> wrote in message
newsfmdnbjnLKNyB4qiU-KYgg@buckeye-express.com...

Oh well it might have been funnier with the actual drawing. Man I need to
get out more...

I understand there are occasionally sightings of 'wild bike riding' women
when our sorts take to jogging 1/2 a block.


(I haven't tried jogging a full block ... my luck, I'd run into wild cement
truck driving women ... )

 

[William Hayes]

"Mike Russell" <geigy@pacbell.net> wrote in message
news:YOXRa.577$ZI2.105@newssvr24.news.prodigy.com...

A friend of mine took an electronics class at a local JC, and he learned
"Ohm's Three Laws": E=IR, I=E/R, and R = E/I.

That'll teach me to let my education lapse.

I remember Charles Coulomb, and how charged objects have force; F ~
(q*q1)/d^2
which relates in some small way to an electric field having force, magnitude
and direction.
Giving the Electric potential equaling the work done (force, magnitude, and
direction of the energy) divided by charge.
Which explains George Ohm's law E=I*R. Claiming there is 'three' is just
comical.

Ask your buddy about Van De Graaf Generators and how ohm's three laws apply.

That should be even more comical.

 

[William Hayes]

"Frank Bemelman" <bemelmanx@euronet.nl.invalid> wrote in message
news:3f18549d$0$28888$1b62eedf@news.euronet.nl...

Let's go all nuts and talk about ohmistance & ohmistors from now on

Cripes, You want these guys/gals to actually learn something ??

 

[Ratch]

"Mark Jones" <127.0.0.1> wrote in message
news:nlKdnTidAJvyCoqiU-KYuQ@buckeye-express.com...

Ratch wrote:
"Tim Williams" <tmoranwms@charter.net> wrote in message
news:vhe6u95nd8l13d@corp.supernews.com...
"Ratch" <Watchit@Comcast.net> wrote in message
news:BZmRa.80118$Ph3.9181@sccrnsc04...
While correct and true in all
cases, those formulas are NOT Ohm's law, and it is wrong to
call them that.

Dude, go back to school, Algebra 1. V=IR > I=V/R > R=V/I etc.
The equation can be rearranged to any of the others by simple
multiplication and division by whichever variable.

Tim

I believe everyone on this newsgroup can isolate each of the
terms algebraically. What is your point? What don't you
agree with? What is incorrect? Be specific. Ratch


I think, for "practical" electronics, the "ohmic" and "non-ohmic"
properties of resitance and its implication in the Ohm's Law equation is
largely depreciated. All resistors are likely assumed ohmic except for
specialty devices or applications, most of which deal with temperature and
not voltage. Personally, I find the
voltage-dependant-negative-coefficient
resistances (such as carbon fiber) particularly interesting.


As I pointed out earlier, there is no "Ohm's law equation". I believe

you are referring to the resistance formula R=V/I and its variations, which
is not Ohm's law, although it is often mistakenly called that. Ohm's law is
a property of a material as explained in
http://www.launc.tased.edu.au/online/sciences/PhysSci/done/electric/resistnc/Resistance.htm
which I posted earlier. Did you read it? Ratch

 

[Ratch]

"Chuck Harris" <cfharris@erols.com> wrote in message
news:bf9642$l2a$1@bob.news.rcn.net...

Hi Ratch,

It is not as simple as all that. E = Ri has been called "Ohm's" law for
as far back as my reference library goes, which is 1907. I cannot
verify, but I would presume that the origin of the the alleged misuse
goes even further back.

The publication that gets it wrong first should not be the one to
follow.

In any case, this relation has been called Ohm's law for so long, that
regardless of its origin, it *is* Ohm's law. To try and change the
common usage at this late date would just needlessly confuse the issue.

Calling R=V/I the resistance formula does not seem confusing. What are
you going to call the resistive linearity property of a material as
explained in
http://www.launc.tased.edu.au/online/sciences/PhysSci/done/electric/resistnc/Resistance.htm
if you insist on hijacking its name for something else?

By the way, I can quote a couple of snippets from two good physics books
that back up what the above site contends.

As a possible explanation for the term Ohm's law, consider that the unit
of resistivity has been called the ohm, as a tribute to Georges Ohm.

The equation that describes the relationship of resistance, voltage,
and current would naturally be called the law of resistance, or the
law of the ohm. It wouldn't take much to morph that to ohm's law.

-Chuck, WA3UQV



Good. You finally gave a valid reason for your gripe and did not
deny
my "factoid". I can understand and appreciate your concern and
irritation.
However, these threads are not just read and appreciated by you , I, and
a
select few. There are plenty of lurkers who don't mind learning
something,
and inserting ancillary facts into a discussion is not beyond what is
normally done here. Look at how some of the other threads have morphed.
Anyway, I don't think I was out of line in pointing out that Ohm's law
is
usually used as a misnomer. The choice to keep on doing so is up to the
individual. Ratch