Pushing Neons (fwd)

---------- Forwarded message ----------
Date: Sat, 25 Jul 1998 17:53:00 -0600
From: terryf-at-verinet-dot-com
To: tesla-at-pupman-dot-com
Subject: Pushing Neons

Hi All,
        I have been playing with a high performance charging circuit design
that uses a 15kV 60 mA neon transformer.  I have the design ironed out so
that when the input voltage is 120 volts, the current is about 8 amps.  The
output voltage is 15kV and the current is 60 mA (all RMS values).  This is
charging a 20nF cap to 21 kV peak.  So everything is within specifications
of the components.  

        The first problem is when the gap fails to fire or you are turning
up the variac and the gap hasn't fired yet.  Without the gap firing, the
neon's input current is 20 amps.  The output voltage is still 15kV but the
output current is 115mA.  These levels would be maintained only a short
period of time (several seconds).

        The second concern is that there can be turn-on transients of 30
amps peak (only one cycle) on the input.  The output may see a 250mA peak
for one cycle and a 35 kV output peak. 

        The output transients don't worry me because the gap (or safety gap
or transorbs) will fire and the system will startup.  The voltage and the
current spike is only for one cycle.  Also this transient case is rather
unlikely to occur often.  I am more concerned about the first case where
high input and output currents my be sustained for several seconds.

        My question to those that have "been intimate" with the internal
parts of neon's is do you think these short term over currents will do any


        Terry Fritz