Hi Michel,
thanks for the link!
Jens
Hi Jens,
They do have them for higher voltages as well.
See here a 650V model:
http://au.element14.com/bourns/cmf-rl50a-0/cptc-radial-telecom-50-ohm/dp/1652209
I would put it on the on the 230V side of the transformer. You can
also do it in the 15V line but my experience is that you loose quite a
bit of voltage across those fuses. There could be better ones now that
I don't know about.
Michel
On May 10, 10:34 pm, jb-electronics<[email protected]>
wrote:
Hi Michel,
yes, a PTC fuse is indeed what I need. I_max was not correct, yes,
thanks for the hint.
But where do I plug it in? These PTC fuses are not suitable for voltages
above 100V or so, so the best place for the fuse would be between the
two back to back transformers, right? The voltage there is between
0..15V AC, the maximum current (if we want something like 50mA after the
last transformer, i.e. 27W) is 27W / 15V = 1.8A . So a PTX fuse with
I_trip = 1.8A should do the trick, right?
Jens
I think the I_max that you specify is not really correct. I_max could
be much higher because you're charging a capacitor, it's not a
resistor. It looks like you are after a 542V power supply that can
supply 30mA (16VA/542V). I_max is not really relevant I think. What
you could do is add a PTC resettable fuse (50mA) on the primary side
(230V) of your transformer, that will give you the required
protection.
Michel
On May 10, 8:14 pm, jb-electronics<[email protected]>
wrote:
Hi folks,
for my Nixie tube making I need a power supply with a little more juice
than the 300V @ 10mA Traco module I have been using until now. This is
what I came up with:
I have a nice 400W variac, so if I connect that to a transformer
back-to-back circuitry (serving as a voltage amplification as well as
galvanic seperation), this - after rectification and a smoothing cap, of
course - gives me an adjustable voltage of
U_out_max = SQRT(2) x 230V x (15 : 9) = 542V DC .
Using some kind of gear on the variac knob will allow a reasonably
accurate adjustment of the output voltage. For the back to back
transformers I would like to use 16VA versions, supplying me with
I_max = 16 VA / 542 V x SQRT(2) = 42 mA .
Any mistakes so far?
Anyway, I was wondering what happens if you short the output of this
setup for a short time (< 10 seconds). The transformers I would like to
use are NOT short-circuit-protected. But I suppose for such a short time
this is not critical, is it?
I will include a voltmeter and amperemeter, and if the amperemeter
measures a current above a specified value (let's say 40mA) it will shut
down the output voltage using a relais. This is not a perfect
over-current protection, but the easiest one I can think of at these
voltages. This whole setup is still in the planning, but it is the
simplest design I could imagine.
Is there any major flaw in my design that I did not think of?
Thanks for your input, it is much appreciated.
Jens
--
You received this message because you are subscribed to the Google Groups
"neonixie-l" group.
To post to this group, send an email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/neonixie-l?hl=en-GB.
