Re: Ignition coil (anti-parallel pairs) array and other questions

To: tesla-at-pupman-dot-com
Subject: Re: Ignition coil (anti-parallel pairs) array and other questions
From: "Jim Lux" <jimlux-at-jpl.nasa.gov> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Sun, 18 Jul 1999 14:46:06 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

> 3)I have just finished making a control panel and case for my TC.
Contains 
> the cap, RSG and NST. I have bought an old volt and ampmeter (both 
> analogue). Only problem is they are both for dc. The voltmeter is up to
300 
> Volts and ampmeter up to 3 amps. How do I convert them to ac (240 volts 
> mains here) (and changing the scale the ampmeter uses (want to be able to

> read larger currents?)), if is is possible??

For the Voltmeter:  Hook up a bridge rectifier (to turn AC into DC) and a
suitable filter capacitor ( a few uF will do) across the meter.  Then,
you'll have to put a series resistor in series with the meter to adjust the
range.  Does the meter have any markings indicating what it's full scale
current is?  (Typically something like 1 mA, or 50 uA)

For the Ammeter: You need to put a small value, high current resistor in
parallel with the meter to adjust the range.  The value depends on the
resistance of the ammeter. You'll also need to put a bridge rectifier and
filter cap on.