Re: Identifying and Adapting Meters

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>

I'd be interested in the link. I did a Google and
checked on shareware.com, but didn't find it.

thanks
Adam

--- Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: David Speck <Dave@xxxxxxxxxxxxxxxx>
>
> Paul.
> There's nothing at all stupid about recycling meters
> at all. I do it often.
>
> The meters are probably marked with a Plus sign on
> one terminal.  If not,
> the + terminal is probably the one that had the red,
> white or yellow,
> orange or brown wire on it (negative colors are
> usually black, blue,
> violet, or gray for American designed circuits).  If
> the unit came from
> Japan, then the white wire is probably the + lead,
> and any other color for
> the negative, but there is no absolute rule.
>
> If you have an adjustable DC power supply, just
> connect the supply with the
> proper polarity in series with a 10K resistor, your
> meter under test,  and
> an inexpensive digital volt meter set on the
> milliampere range.  Start with
> the supply at 0 volts, and increase the output
> slowly.  If the meter
> deflects backward, you have the polarity wrong.
> If it deflects forward, then advance the power till
> you have a full scale
> reading, and consult your handy DVM to see what the
> full scale current is.
> You may need to increase or decrease the test 10K
> resistor to get a full
> scale deflection.  If you have to apply lots of
> voltage to get even a
> little movement, then there is probably an internal
> scaling resistor inside
> the meter.  With careful disassembly, this can be
> removed, or, more simply,
> shorted out to get the max sensitivity from the
> meter movement.
> After you find out what current gives you a full
> scale deflection, you can
> apply your DVM across the meter terminals, adjust
> for a full scale
> deflection again with just the power supply and the
> temporary scaling
> resistor, and see the voltage drop across the meter.
>  Using R=I/E, you can
> then determine the internal resistance of the meter
> coil.  With these
> parameters, you can select a scaling resistor to
> make the meter display
> just about anything you want for a full scale
> reading.
>
> Having said that, and NOT having looked at the Tesla
> Tuner schematic in a
> while, IIRC, the tuner feeds AC to the LEDs, and
> relies on the human eye to
> integrate the pulses of light to balance the two
> LEDs' output.
> If that is correct, a DC meter won't help you.  You
> will have to build a
> simple precision rectifier (otherwise known as an
> absolute value circuit)
> with an op amp, a pair of diodes and a few
> resistors.  Circuits for these
> are easily found with a Google search.
> BTW, there's a really neat shareware program out
> there called MeterScale or
> something to that effect, that makes very nice
> custom meter faceplates with
> your choice of legend and graduations.  Definitely
> worth the $10.00
> registration fee, and makes a very professional
> looking replacement meter
> face of nearly any conceivable size, scale,and
> configuration..  I can
> forward you a copy or a link if you are interested.
>
> HTH,
> Dave Speck
>
> >I would like to use one of these to indicate the
> output level of the Tesla
> >Coil Tuner, in addition to or in place of the LED.
> Any help will, of
> >course, be greatly appreciated. I will even accept
> well intentioned
> >criticism about what a stupid idea this is!!
> Regards.
> >Paul
> >Think Positive
>
>
>