Re: Ammeter Question

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

Original poster: dhmccauley-at-spacecatlighting-dot-com 

I would strongly recommend against using a digital handheld multimeter
unless its something that wouldn't mind losing.
Tesla coil circuits can have the tendency to put nice transients back on
your input power feed and i wouldn't want to risk
having a nice multimeter die because of one of them.

I would rather use a true analog meter, or better yet, a clamp-on meter for
measuring current.

Dan




 >  > Where can I find an AC ammeter to go inline with my hot power supply? I
 >  > would like to be able to measure the amps the transformers are drawing.
 >  >
 >  >
 >  >
 > Digi-Key sells panel mount analog meters up to 50 amps a/c for $71.80 part
 > # is 180-1079-ND.
 >
 > If you are running under 1Kva, you can probably use your handheld
 > multimeter, just read the owners manual first, mine are only good up to 10
 > amps for short time periods.  If you are running high powers, you can use
 > an amp clamp or a current transformer.
 >
 > I had this problem when I began useing more powerfull supplies.
 > Fortunately, I salvaged a 100:5 current transformer several years ago.  I
 > never new how to use it, but I found out on the list.  These are expensive
 > when new but you can find them as surpluss.  The critical part in my
 > circuit is a .2 ohm 5 watt current sense resistor.  This allows me to
 > place my digital meter across the secondary, and if the circuit sees 100
 > amps, my meter only sees 5 amps.  I have to multiply the reading by 20,
 > but it works beautifully.  I use a gapped E-I core ballast, thie current
 > monitor allows me to calibrate the ballast.
 >
 > Look for used panel meters or current transformers at Murphy's in El
 > Cajon, CA, C and H sales in Pasadena, or Gateway electronics, in San
 > Diego,  I think they all have websites.
 >
 > Good Luck and Safe Coiling,
 >
 > Thad Howard
 >
 >
 >
 >
 >