Maker Pro
Maker Pro

Convert 12-14 vdc to 9 vdc for a device only needing 0.3ma...

L

linnix

Jan 1, 1970
0
I remember Duracell had batteries with an indicator.
You could press it, and it would show how much was left in the battery.
It was a thermal strip that changed colour, so it emptied the batteries too,
increasing sales of course...
If you can make it cheap enough it may work., although few people will open
their car an look at the battery... In the dashboard..
do the majority of people even know what a battery *is*,
and if their car has one ???

Even my wife knows about the car battery, but nothing else. My
corolla has analog meter, but difficult to tell the exact reading.
Her Luxus does not even have analog meter. After her last dead
battery, she is well informed about monitoring the voltage. My meter
plugs into the cigarette socket. She will let me know if the reading
is below 11V. Just to be sure, I would probably wire a three color
led based on the battery voltage. She wouldn't ignore it if the color
turns yellow or red.
 
J

Jasen Betts

Jan 1, 1970
0
I remember Duracell had batteries with an indicator.
You could press it, and it would show how much was left in the battery.
It was a thermal strip that changed colour, so it emptied the batteries too,
increasing sales of course...
If you can make it cheap enough it may work., although few people will open
their car an look at the battery... In the dashboard..
do the majority of people even know what a battery *is*,
and if their car has one ???

Yuasa makes car batteries with a charge indicator.
One of the caps has a built in hydrometer and some optics.
that change colour when discharged and (a different colour)
for low electrolyte.
 
R

Rich Grise

Jan 1, 1970
0
I doubt it drew more than, say, 50-100mA, so if the typical test time was
5-10 seconds, unless you were testing your batteries an awful lot, I doubt
it measurably increased Duracell's sales. :)
Good Grief! It was a strip of liquid crystal, which are famous for drawing
well under one mA, more like microamps.

Hope This Helps!
Rich
 
R

Rich Grise

Jan 1, 1970
0
Even my wife knows about the car battery, but nothing else. My corolla
has analog meter, but difficult to tell the exact reading. Her Luxus does
not even have analog meter. After her last dead battery, she is well
informed about monitoring the voltage. My meter plugs into the cigarette
socket. She will let me know if the reading is below 11V. Just to be
sure, I would probably wire a three color led based on the battery
voltage. She wouldn't ignore it if the color turns yellow or red.

So, in other words, Lexi are crap? (assuming by "Luxus", you mean "Lexus")

Thanks,
Rich
 
J

JosephKK

Jan 1, 1970
0
Screw you.
I just happen to have 2 of those cheap meters the poster is
referring to, that was given to me in a grab bag. I gutted one of them
to use
as a display in a junk project, the unit can read it's own source just
fine if that is what every one is so worried about.

If you want to talk about some one giving bad advice, take a look
in the mirror assole.

Unless they have changed the design of those 3..5 dollar DMM's
at the freight, it'll work just fine..

So go screw your self Terrell until you have something
worth while to say, with out vile and excrement rolling out your pie hole.

I don't give a shit how disabled you are and how that makes you feel
that it give's you the ok to be a royal asshole with just about every
one you intersect with.

There are a lot of disabled people out there on their last leg, you
aren't anything special.

fringing ignorant old basted, thinks the world owes him something.


http://webpages.charter.net/jamie_5"

A tad touchy? NOT creating warm fuzzy feelings about your real
competence by my reading.

Michael has given more to the world than you ass-ume. I have yet to
see similar contributions from you.
Not that i have much to brag about, but i have paid my freight.
 
J

JosephKK

Jan 1, 1970
0
Do you now have comprehension problems? Was my post that unclear to you?

You must be among those ignorant saps that represents the greater
whole of the moron society this country is quickly getting polluted
with.

Go dig a hole while you still can. Cause when its time for you to
go, I doubt many will notice.


http://webpages.charter.net/jamie_5"

I will personally notice Michael's demise, but i won't even deign to
acknowledge yours, though it has already happened.
 
J

Jamie

Jan 1, 1970
0
JosephKK said:
A tad touchy? NOT creating warm fuzzy feelings about your real
competence by my reading.

Michael has given more to the world than you ass-ume. I have yet to
see similar contributions from you.
Not that i have much to brag about, but i have paid my freight.
Excuse me?

I guess you must one of the sheep being herded.

I feel sorry for your incompetence to see between the cracks.

I don't try to lead any one, especially ways that a few do in this
arena, but if that is what you wish for, so be it.

I stand on my original content of this post! Just because the present
day design of those cheap meters no longer allow the measurement of its
own supply rail as many do not. I have 3 in my possession that do and
can confirm they are not the same board design as was posted from a
poster here, which I can't remember at the moment who it was.

It's all about how the meter is design, using a virtual ground from a
signal source.

Have you ever heard of differential and single ended systems?

One requires a VG which makes it inadequate to measure it's own
rails and the other, does not.

Next time you're looking around for panel LCD's, pay close
attention to the spec's that allow you a floating common and non
floating. That
mays all the difference..

Now let me get back to something worth doing and it's not talking to
sheep like you.

P.S.

I don't step aside for those that think the world owns them
something.


http://webpages.charter.net/jamie_5"
 
L

linnix

Jan 1, 1970
0
I stand on my original content of this post! Just because the present
day design of those cheap meters no longer allow the measurement of its
own supply rail as many do not.

You can externally generate the negative supply or reference voltage.
Neither one is cost effective for cheap meters. By the way, my local
Harbor Freight is out of "cheap meters". The new version with back-
light is $9.99, so $8 for the LED back-light.
Next time you're looking around for panel LCD's, pay close
attention to the spec's that allow you a floating common and non
floating. That mays all the difference..

LCD panels don't care about absolute voltage, as long as value between
segments and commons are fixed. The chip can do both ways. It's just
a matter of cost in the meter design.
 
E

ehsjr

Jan 1, 1970
0
Jamie said:
Excuse me?

I guess you must one of the sheep being herded.

I feel sorry for your incompetence to see between the cracks.

I don't try to lead any one, especially ways that a few do in this
arena, but if that is what you wish for, so be it.

I stand on my original content of this post!

That seems an untenable position, so you may have more
in mind that what was posted.

Your original post was: "yes, use a couple of diodes
in series." in response to the question: "Is there an easy
(read cheap) way to drop the 12-14 volts down to 9 volts
without increasing the power consumption very much?"

1) It has been shown that there are meters that won't work
properly when measuring their own source. Your post makes
no allowance for that.
2) A couple of diodes will not drop 12-14 volts down
to 9 volts.

You might have something different in mind, but people
are reacting to what you posted, not what you have in
mind (assuming it is different). I'm interested in
what your specific thinking is, assuming your statement
about a couple of diodes did not truly reflect that.

I'm in the (slow) process of adding metering to a physically
(relatively) large cabinet that houses a 12-15V switcher. I
have 3 different DC-DC converters breadboarded. The cmos 555
version I mentioned in this thread works best, so far. In any
event, adding two of those Harbor Freight meters is the cheapest
way to go, so that makes it attractive. Now, if you have
strong reason to know that they will work properly and not
be damaged by a source that is 42% higher than nominal, I may
be able to omit a zener from the DC-DC design. The switcher is
already complete, it's just the meter supply that prompts
the question.

Ed
 
J

Jasen Betts

Jan 1, 1970
0
Good Grief! It was a strip of liquid crystal, which are famous for drawing
well under one mA, more like microamps.

it was a tapered thick film resistor acting as a heater behind a thermal colour-change
compound.
 
J

Jamie

Jan 1, 1970
0
ehsjr wrote:

That seems an untenable position, so you may have more
in mind that what was posted.

Your original post was: "yes, use a couple of diodes
in series." in response to the question: "Is there an easy
(read cheap) way to drop the 12-14 volts down to 9 volts
without increasing the power consumption very much?"
yes, that was in response to dropping the voltage supply
from 12 down to ~ 9 volts cheaply..
1) It has been shown that there are meters that won't work
properly when measuring their own source. Your post makes
no allowance for that.
Not all can measure their own rail, that's true.
Those using virtual grounds will most likely not be able
to do this.
2) A couple of diodes will not drop 12-14 volts down
to 9 volts.

Each diode will give you a loss of ~ 0.6 volts.
2 diodes will give you around 1.2 volt drop.
so maybe more is needed, But the idea was put in place
so a simply solution was at hand.
You might have something different in mind, but people
are reacting to what you posted, not what you have in
mind (assuming it is different). I'm interested in
what your specific thinking is, assuming your statement
about a couple of diodes did not truly reflect that.

Diodes are and have been a simply solution for years to drop
the voltage level a bit.
I'm in the (slow) process of adding metering to a physically
(relatively) large cabinet that houses a 12-15V switcher. I
have 3 different DC-DC converters breadboarded. The cmos 555
version I mentioned in this thread works best, so far. In any
event, adding two of those Harbor Freight meters is the cheapest
way to go, so that makes it attractive. Now, if you have
strong reason to know that they will work properly and not
be damaged by a source that is 42% higher than nominal, I may
be able to omit a zener from the DC-DC design. The switcher is
already complete, it's just the meter supply that prompts
the question.

Ed
I recently saw a photo of the inside of a freight meter, it does not
look like the one's I have. Those M-830B's have been around for years
and i'm sure the internal board design has been changed several times.
The 3 I have, can! and I repeat can measure it's own source. But mine
are over 5 years old now. That does not mean the new ones are designed
the same way.

Why can't you just get one of those cheap LCD panel meters?
http://www.futurlec.com/Panel_Meters.shtml

http://webpages.charter.net/jamie_5"
 
L

linnix

Jan 1, 1970
0
I recently saw a photo of the inside of a freight meter, it does not
look like the one's I have.

That's why they are cheaper. They removed the external voltage
references.
Why can't you just get one of those cheap LCD panel meters?http://www.futurlec.com/Panel_Meters.shtml

My plan is to install rechargeable batteries on them, and charge
through the 10A plug (cutting the internal wire, of course). I can
still use them as regular meters, without turning them off or
replacing batteries. They were steals at $1.99, but not anymore.
They were all stolen from my local Harbor Freight.

I installed the meter on the ignition wire tap in my wife's car.
Knowing her, it will always be on or off. I prefer it always on with
key in ignition.
 
J

JosephKK

Jan 1, 1970
0
Excuse me?

You seem to need an excuse, but i will not grant you one today.
I guess you must one of the sheep being herded.
Non-sequitur.


I feel sorry for your incompetence to see between the cracks.

The cracks in your garbage claims i do see through, but they are
several feet wide.
I don't try to lead any one, especially ways that a few do in this
arena, but if that is what you wish for, so be it.

You lead? Now that is a joke.
I stand on my original content of this post! Just because the present
day design of those cheap meters no longer allow the measurement of its
own supply rail as many do not. I have 3 in my possession that do and
can confirm they are not the same board design as was posted from a
poster here, which I can't remember at the moment who it was.

I do not recall any poster saying that not being able to measure its
own source was a good design, not even yourself. I recall many
reports of meters that could not do so.
It's all about how the meter is design, using a virtual ground from a
signal source.

Have you ever heard of differential and single ended systems?

Maybe before you were born, must have been 50 years ago.
One requires a VG which makes it inadequate to measure it's own
rails and the other, does not.

Next time you're looking around for panel LCD's, pay close
attention to the spec's that allow you a floating common and non
floating. That
mays all the difference..

Now let me get back to something worth doing and it's not talking to
sheep like you.

P.S.

I don't step aside for those that think the world owns them
something.


http://webpages.charter.net/jamie_5"

I claim that "I have earned all that i have, some of it many times
over."
 
E

ehsjr

Jan 1, 1970
0
Jamie said:
ehsjr wrote:



yes, that was in response to dropping the voltage supply
from 12 down to ~ 9 volts cheaply..


Not all can measure their own rail, that's true.
Those using virtual grounds will most likely not be able
to do this.



Each diode will give you a loss of ~ 0.6 volts.
2 diodes will give you around 1.2 volt drop.
so maybe more is needed, But the idea was put in place
so a simply solution was at hand.

Ok, thanks. I was hoping you might have done enough testing
to be sure that running one of those meters at ~12.8V would
not damage it and that it would work properly at that voltage.

Diodes are and have been a simply solution for years to drop
the voltage level a bit.


I recently saw a photo of the inside of a freight meter, it does not
look like the one's I have. Those M-830B's have been around for years
and i'm sure the internal board design has been changed several times.
The 3 I have, can! and I repeat can measure it's own source. But mine
are over 5 years old now. That does not mean the new ones are designed
the same way.

Why can't you just get one of those cheap LCD panel meters?

I can do that, and have in the past for smaller things. But you
can't beat a $2.99 (sale) price tag for the Harbor Freight meter,
and I have plenty of space in the cabinet to mount the entire meters
in the front panel, if I want. And the test leads will be used
to connect the supply to whatever it is powering.

Ed
 
J

Jamie

Jan 1, 1970
0
ehsjr said:
Ok, thanks. I was hoping you might have done enough testing
to be sure that running one of those meters at ~12.8V would
not damage it and that it would work properly at that voltage.




I can do that, and have in the past for smaller things. But you
can't beat a $2.99 (sale) price tag for the Harbor Freight meter,
and I have plenty of space in the cabinet to mount the entire meters
in the front panel, if I want. And the test leads will be used
to connect the supply to whatever it is powering.

Ed
I was just at the local junk store that carries like 75% of goods like
harbor freight does and they have a whole shelve of them.
$5.99

The model number isn't exactly like my 5 year old ones but close.
I think theirs is a DT or BT-830B, mine is M-830B.
I couldn't tell you what the board design of that model is.
I didn't feel it was necessary to buy yet another junk meter
to have lying around.


http://webpages.charter.net/jamie_5"
 
G

Greegor

Jan 1, 1970
0
Somebody said forward bias on 1N4001 diode would be .6V
but I was taught that silicon diodes forward bias at .5.

I wouldn't quibble about the difference but when using
a whole string of those for a voltage drop wouldn't
that become a big deal?

Is forward bias on silicon diodes actually .6 v or .5 v as I was
taught?
 
E

Eeyore

Jan 1, 1970
0
Greegor said:
Somebody said forward bias on 1N4001 diode would be .6V
but I was taught that silicon diodes forward bias at .5.

I wouldn't quibble about the difference but when using
a whole string of those for a voltage drop wouldn't
that become a big deal?

Is forward bias on silicon diodes actually .6 v or .5 v as I was
taught?

Depends on the current.

Graham
 
J

Jon Kirwan

Jan 1, 1970
0
Somebody said forward bias on 1N4001 diode would be .6V
but I was taught that silicon diodes forward bias at .5.

I wouldn't quibble about the difference but when using
a whole string of those for a voltage drop wouldn't
that become a big deal?

Is forward bias on silicon diodes actually .6 v or .5 v as I was
taught?

Aside from structure and materials, the voltage drop depends also on
the current. For base-emitter junctions on common silicon BJTs my
experience says the drop varies at about 60mV per 10-fold change in
current -- consistent with this model:

Vd(I) = n k T / q * ( ln(I) - ln(Is) )

Since Is is a constant, ln(Is) is also constantand drops out of the
derivative. So you get:

d Vd(I)
------- = n k T / q
d ln(I)

With q the electron charge, k Boltzmann's constant, T is temperature
(Kelvin), and n is a fudge factor (okay, 'emission coefficient') that
is mostly 1 for BJTs. kT/q at ambient temperature works out close to
60mV (just under.)

For diodes, my experience seems to be that 'n' is no longer close to 1
and is not infrequently significantly closer to 2 than to 1. So I'd
expect more like 100mV change in diode voltage for a 10-fold current
change. For the common 1N4148 diode, I mentally estimate 0.5V at
100uA and 0.6V at 1mA and work up or down from those.

For LEDs, yet another story despite them being diodes, too.

So the way I'd take all this is that it depends on the current under
consideration and the part being used. You might see someone say 0.5V
(and less) when they are talking about microamp ranges of currents and
say 0.6V for low milliamps and still more if the currents are higher
still. So... it depends on context.

Jon
 
E

Eeyore

Jan 1, 1970
0
Joel said:
I've never heard the 0.5V number, but that doesn't mean much. Possibly chip
designers who are working down in the microamp arena use it?

I tend to expect Vbe of BJTs to be in the 0.55V area with collector currents of a
milliamp or so.

Graham
 
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