Re: Ammeter Configurations

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Mike" <mikev-at-eastcoastind-dot-com> 

Hi Gary and all,
                               Returning the message from work here. Reading
in the current mode the meter is so heavily shunted spikes are not a
problem. This is done on large plasma arc discharges and I would say the
trash on the line is about as bad as a coil. Same variables.
Using larger value "resistors" I can get enough rise voltage (especially at
the current I pull, testing the rating of 3 pole pigs on our 3 phase drop)
to drop a dc signal into small averaging cap. A one or two second time
constant gives nice readings, the meter never sees the trash.
Analog meters are nice, I like them too but in our automated reading system
the computers want a digital interface. I meter the HV earth grounded DC
output this way also and those are ~860 Amp large cap dumps to plasma with
2600 volts.
Well, I guess he will do what he will do.
Regards,
Mike
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, October 05, 2004 9:40 AM
Subject: RE: Ammeter Configurations


 > Original poster: "Lau, Gary" <gary.lau-at-hp-dot-com>
 >
 > I would recommend the use of an analog meter over a digital multimeter
 > for a couple of reasons.
 >
 > I have not tried it to measure current, but I have seen my multimeter
 > wink out to never-never land when I monitored my mains voltage, due to
 > the transient spikes present.  Happily it came back after power cycling
 > the meter (I GOTTA get some MOV's!).  I can't say whether the same will
 > happen when measuring current, but I personally wouldn't risk my DMM.
 >
 > DMM's are good for measuring stable readings, but the load current to a
 > Tesla coil will vary widely, rapidly, and randomly, and the display will
 > be an utterly useless jumble of numbers.  An analog meter will
 > time-average the fluctuations and provide a far more useful reading, as
 > well as being more tolerant of transient spikes.
 >
 > Regards, Gary Lau
 > MA, USA
 >
 >  > Original poster: "Mike" <induction-at-comcast-dot-net>
 >  >
 >  > Hi Tristan,
 >  >                   About your amp meter, first I will assume you also
 > own a
 >  > digital multimeter as they are not expensive and most technical people
 > have
 >  > one.
 >
 > <snip>
 >
 >  > ----- Original Message ----- From: "Tesla list" <tesla-at-pupman-dot-com>
 >  > To: <tesla-at-pupman-dot-com>
 >  > Sent: Monday, October 04, 2004 9:45 AM
 >  > Subject: Ammeter Configurations
 >  >
 >  >
 >  > >Original poster: "Tristan Steele" <ozonejunkie-at-westnet-dot-com.au>
 >  > >G'day All,
 >  > >
 >  > >I am in the process of trying to work out a way to measure AC voltage
 > and
 >  > >current flowing into my coil, and have run into a few problems in the
 >  > >availability (and price) of AC meters.  I have worked out a method to
 > use
 >  > >the much cheaper DC versions that I can easily get.  Can someone
 > please
 >  > >offer some advice on if this setup will work, or if I have missed
 > some vital
 >  > >point. (Wouldn't surprise me!).
 >  > >
 >  > >The schematic can be found at:
 >  > >http://members.westnet-dot-com.au/gemabrown/meterschem.png
 >  > >(Only ~9.73kB)
 >  > >
 >  > >Any guidance would be appreciated,
 >  > >
 >  > >Thanks
 >  > >Tristan
 >  > >
 >  >
 >  >
 >
 >
 >