Re: Using a Panel Meter movement

On Sep 15, 7:43*am, "Patrick Keenan" <t...@dev.null> wrote:
> Hello All,
>
> I'm trying to sort out how to use an analog, needle-style, coild&spring type
> of panel meter movement. * I have a couple of samples to play with,
> unfortunately I have no infomation about them. * On one, the needle rests on
> the left, on the other, the in the center - this is actually the one I am
> most interested in using.
>
> For clairty this is the kind of device I'm referring to:http://www.process-controls.com/Modt...meters_Magcent...
>
> So I'm looking for a sample circuit that shows me how this sort of movement
> is connected and driven, or just what words to use on Google to find such
> circuits, and how to figure out details on the samples I have. * I'm finding
> lots of results on meters except for how to do this.
>
> I'm intending to use this movement to indicate whether a signal is above or
> below a given value - if you think of a guitar tuner, that's probably a
> helpful example.
>
> Thanks!
> Patrick Keenan

use a meter whith known values in a circiut to set your full scale
deflection on your VU meter for what your going to measure

what the application.
what are you tring to measure

it realy does not matter where the meter rests that is just a mechanical function. usualy panel meter defects full scale about 50micro amps. but with a shunt across it can deflect with 100 amps. the trick is to find out what is the full scale deflection in units value that it can read. Then anything with a correct shunt across the meter can be used to read other values. use a battery 1.25v and add a resistor in series of such a value that only 50micro amps can flows. see what kind of deflection you get 1/3 full whatever then calculate or adjust full scale deflection then you will know what meter you got. be carefull not to blow it up with too much I.

Patrick Keenan wrote:
>
> <(E-Mail Removed)> wrote in message
> news:2f70ab98-4775-4ec0-b544-(E-Mail Removed)...
> On Sep 15, 7:43 am, "Patrick Keenan" <t...@dev.null> wrote:
>
>> Hello All,
>>
>> I'm trying to sort out how to use an analog, needle-style,
>> coild&spring type
>> of panel meter movement. I have a couple of samples to play with,
>> unfortunately I have no infomation about them. On one, the needle
>> rests on
>> the left, on the other, the in the center - this is actually the one I am
>> most interested in using.
>>
>> For clairty this is the kind of device I'm referring
>> to:http://www.process-controls.com/Modt...meters_Magcent...
>>
>>
>> So I'm looking for a sample circuit that shows me how this sort of
>> movement
>> is connected and driven, or just what words to use on Google to find such
>> circuits, and how to figure out details on the samples I have. I'm
>> finding
>> lots of results on meters except for how to do this.
>>
>> I'm intending to use this movement to indicate whether a signal is
>> above or
>> below a given value - if you think of a guitar tuner, that's probably a
>> helpful example.
>>
>> Thanks!
>> Patrick Keenan
>
>
> use a meter whith known values in a circiut to set your full scale
> deflection on your VU meter for what your going to measure
>
> what the application.
> what are you tring to measure
>
> =====
> Thanks for the reply. For application, think "guitar tuner".
> What is being measured is an incoming frequency, relative to a specific
> reference, so the needle rests in the middle and moves right or left.
> There's a microcontroller involved, so I assume that I'll be converting
> that incoming frequency to a voltage to run the meter itself. The
> meter won't be the only display, but I find that for me, the needle
> movement is the best visual cue.
>
> Do you know of any sample circuits so I can see what sorts of voltages
> and currents are normally acceptable for this kind of movement, and how
> they are normally connected? Or a sample datasheet? These seem
> harder to find than I expected.
>
> Thanks again,
> Patrick Keenan

The meter is driven by current. The voltage level powering
a microprocessor will be fine, but the current *must* be
limited to less than 100 ua, per the page you posted.

Assuming a 5 volt supply, you can use a 2 meg resistor in
series to limit the current to no more than 50 uA to give
yourself a wide safety margin when testing the meter.

Your actual circuit will dictate how the thing is wired when
in use, but in general it will have a fixed and a variable
resistance in series. The variable resistance is used to
calibrate the full scale meter reading. Something like this:

R1 VR1
+---/\/\/\----/\/\/\
| ^
| |
[Source] [Meter]
| |
+----------------+

Source in the diagram is whatever circuit element drives the
meter - transistor, op amp, uprocessor, whatever.

Ed

On Sep 15, 12:37*pm, ehsjr <eh...@NOSPAMverizon.net> wrote:
> Patrick Keenan wrote:
>
> > <extremesoundandli...@yahoo.com> wrote in message
> >news:2f70ab98-4775-4ec0-b544-(E-Mail Removed)....
> > On Sep 15, 7:43 am, "Patrick Keenan" <t...@dev.null> wrote:
>
> >> Hello All,
>
> >> I'm trying to sort out how to use an analog, needle-style,
> >> coild&spring type
> >> of panel meter movement. I have a couple of samples to play with,
> >> unfortunately I have no infomation about them. On one, the needle
> >> rests on
> >> the left, on the other, the in the center - this is actually the one Iam
> >> most interested in using.
>
> >> For clairty this is the kind of device I'm referring
> >> to:http://www.process-controls.com/Modt...meters_Magcent...
>
> >> So I'm looking for a sample circuit that shows me how this sort of
> >> movement
> >> is connected and driven, or just what words to use on Google to find such
> >> circuits, and how to figure out details on the samples I have. I'm
> >> finding
> >> lots of results on meters except for how to do this.
>
> >> I'm intending to use this movement to indicate whether a signal is
> >> above or
> >> below a given value - if you think of a guitar tuner, that's probably a
> >> helpful example.
>
> >> Thanks!
> >> Patrick Keenan
>
> > use a meter whith known values in a circiut to set your full scale
> > deflection on your VU meter for what your going to measure
>
> > what the application.
> > what are you tring to measure
>
> > =====
> > Thanks for the reply. * For application, think "guitar tuner". * * *
> > What is being measured is an incoming frequency, *relative to a specific
> > reference, so the needle rests in the middle and moves right or left. *
> > There's a microcontroller involved, so I assume that I'll be converting
> > that incoming frequency to a voltage to run the meter itself. * The
> > meter won't be the only display, but I find that for me, the needle
> > movement is the best visual cue.
>
> > Do you know of any sample circuits so I can see what sorts of voltages
> > and currents are normally acceptable for this kind of movement, and how
> > they are normally connected? * Or a sample datasheet? * * These seem
> > harder to find than I expected.
>
> > Thanks again,
> > Patrick Keenan
>
> The meter is driven by current. The voltage level powering
> a microprocessor will be fine, but the current *must* be
> limited to less than 100 ua, per the page you posted.
>
> Assuming a 5 volt supply, you can use a 2 meg resistor in
> series to limit the current to no more than 50 uA to give
> yourself a wide safety margin when testing the meter.
>
> Your actual circuit will dictate how the thing is wired when
> in use, but in general it will have a fixed and a variable
> resistance in series. The variable resistance is used to
> calibrate the full scale meter reading. Something like this:
>
> * * * * * R1 * * * *VR1
> * * +---/\/\/\----/\/\/\
> * * | * * * * * * * *^
> * * | * * * * * * * *|
> [Source] * * * * [Meter]
> * * | * * * * * * * *|
> * * +----------------+
>
> Source in the diagram is whatever circuit element drives the
> meter - transistor, op amp, uprocessor, whatever.
>
> Ed- Hide quoted text -
>
> - Show quoted text -


how about I just give you guitar tuner schematic so the resisters are
already set for your frequency dividing network to match A B C D E F
and G would that be better for you the VU meter just measures the
voltage difference a good one measures variance in current and
Voltage.

"ehsjr"


> The meter is driven by current. The voltage level powering
> a microprocessor will be fine, but the current *must* be
> limited to less than 100 ua, per the page you posted.
>
> Assuming a 5 volt supply, you can use a 2 meg resistor in
> series to limit the current to no more than 50 uA to give
> yourself a wide safety margin when testing the meter.


** Huh ???

100k is the value needed.



....... Phil

Phil Allison wrote:
> "ehsjr"
>
>
>
>>The meter is driven by current. The voltage level powering
>>a microprocessor will be fine, but the current *must* be
>>limited to less than 100 ua, per the page you posted.
>>
>>Assuming a 5 volt supply, you can use a 2 meg resistor in
>>series to limit the current to no more than 50 uA to give
>>yourself a wide safety margin when testing the meter.
>
>
>
> ** Huh ???
>
> 100k is the value needed.


Thanks! You are correct, of course. My error.

Ed

>
>
>
> ...... Phil
>
>
>
>
>
>