Hi Ron, Klaus, motion, Phasor,
Yes, a cap is a very easy way, thats what i'm using at
the moment. The value, i found optimal is 0.47 Mfd.
But this gear is old, and it keeps blowing bulbs.
I think its due to the odd poor connection causing too
much current through the cap due to spikes and or rough
bits on its supply.
Also cos this machine is old and cranky, i still go over
to it and listen carefully to hear the 'hiss' from the
element, just to be sure that it is working as it should!
So i thought, if i can run it with a ferrite hoop or a
small transformer, that would suit me fine. I would know
the element was running if the bulb is on, and roughness
on the supply shouldn't affect it.
As to the open circuit voltages on a 'current transformer'
yes, they do give very high voltages with no load, they
are made so that several instruments can be connected to
them in series with almost no effect on the intended
current to the instruments, that is a specific situation.
With a 'current transformer' one could short together the
output and still get the intended current. The output
current is determined (mostly) by the resistance of the
output winding.
In this case, it would act more like a normal transformer
with a fairly high differential. (well thats my opinion)
I feel that LEDs would look out of place on this old M/C
but the suggestion of limiting with zeners has occurred to
me in a slightly different way, i tried to limit the excess
voltage that the lamp may get by putting a small neon bulb
across it. That didn't work and after two days i lost
another lamp, upon inspection i saw that the neon had its
resistor in the black insulation tubing right close up to
the bulb - so it wouldn't have done much limiting!
If i try that again i will include a four or five hundred
ohms in line too, and remove the resistor from the neon.
I know the neon could only limit it to sixty-plus volts,
but i reckoned that the lamp could probably take that sort
of spike alright.
Thank you all for your interest and suggestions, i think
i will make a start on winding some turns!
Regards, John