Re: 60 vs. 30 ma
Subject: Re: 60 vs. 30 ma
Date: Tue, 10 Jun 1997 11:46:29 -0500
From: "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
> Date: Sat, 07 Jun 1997 19:47:32 -0500
> To: tesla-at-poodle.pupman-dot-com
> Subject: 60 vs. 30 ma
> From: Tesla List <tesla-at-pupman-dot-com>
> Subject: 60 vs. 30 ma
> Date: Sat, 07 Jun 1997 15:58:21 -0500
> From: Tedd Payne <tpayne-at-netnitco-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Thanks to those who replied. Maybe I could have asked my question more
> clearly, so I'll try again.
> If I have a well-operating coil using a 12KV/30ma neon transformer, and
> I replace that transformer with a 12KV/60ma transformer:
If it ain't broke, don't try to fix it.
> 1. To take best advantage of the 60ma, should I change the torroid size
> and/or change the primary tap location? (assume the .005uF cap value
> won't change)
The *only* way to reap maximum benefit from changing to a 60 mA neon
xfmer is to double your cap size to 0.01 mfd. During this change you
will be able to enlarge your toroid size, and you will probably have
to reduce the turns tap on your primary (the reduction will be
determined by how big your increased topload is).
> I think I read that by using a larger torroid, a smaller cap could be
> used. Therefore, if I use a 60ma transformer (which would normally call
> for about a .01 cap), I could get away with using the original .005 cap
> by using a larger torroid. Is that correct?
Wrong! You need to add more topload to your given secondary to
*track* any change in the primary which would lower its operating
frequency, such as going from a 0.005 to a 0.01 mfd cap size.
> 2. After changing the torroid size and/or primary tap, what increase in
> spark length should I expect as a result of moving up to 60ma?
Too many variables to give an exact prediction. A safe bet would be
at least 1.5 times the previous discharge length. In my experience a
reasonably good coil with a single 12 kV -at- 60 neon can deliver 30-36
> 3. If I changed only the primary tap location (if that would help) and
> did NOT change the torroid size, what increase in spark length should I
> expect as a result of moving up to 60ma?
Tesla coil tuning has to be right for the operating frequency of the
coil. This has nothing to do with the power supply in general terms
with low powered coils. The higher current neon xfmer can recharge
your system cap faster after each firing of the system gap because it
has a lower source (internal) impedance and increased power delivery
ability. In order to best utilize this increased charging current,
you need to increase the size of your system cap. The bigger
transformer will be able to charge it at the same fast rate that the
smaller 30 mA xfmer was able to charge the smaller 0.005 mfd cap.
Trouble is with the bigger system cap the operating frequency of the
system just dropped, so now you gotta compensate your secondary to
resonate lower frequency as well. Adding a bigger topload is one
easy way. Another is to add secondary turns with the existing
> Thanks again,
Is this clearer than mud now? : )