Single mosfet bifiliar gdt

[aie212]

hey ..
I tried to make another sstc based on steve half bridge ..
but i want it to work only 1 mosfet .. for simplicity.
I also removed the 7414 and connected the secondary directly to the gate driver ..

well .. is it safe to connect the secondary directly to the gate driver ..
outside the schematic and it appears in the photo I add RC

[davekni]

That is a nice little driver chip with plenty of input hysteresis.  It should work just fine without 7414.

[aie212]

thanks for the response Dave ..
but is it safe to connect directly to the secondary ..?
because with the antenna, I only got a 2cm small arc

[davekni]

If connecting to the bottom of the secondary winding without a current-transformer, you will need higher-current diodes than 1N60, perhaps  1N5819 (1A schottky).  Even a 3A schottky diode wouldn't hurt depending on your coil's secondary impedance.  (There is also a possibility that the secondary current could over-drive the 12V supply - feed more average current through the upper diode than the gate drive needs.  Haven't heard of that occurring in practice, but such is theoretically possible.)  Perhaps a 12V TVS diode across the 12V supply would be a good idea just in case.  Or use a current transformer to reduce the feedback current.

[aie212]

good dave .. 
I've tried antenna and CT
but still a little bow that I got ..
until I connect directly ..
and got a long bow like in the video ..
currently i am using 1N4148 according to the attached schematic ..
I will try to replace the 1N5819 according to your suggestion ...
thank you for the advice and input 

[aie212]

final test
clamp diode change
GDT changes

[davekni]

Nice performing coil!

[aie212]

thanks Dave ..
I thought .. for a mosfet the irfp460 might be the maximum
with a voltage of 180 volts from the 5ampere transformer voltage multiplier
I tried it for 30 minutes it just felt warm ..
and it's time to pack it well ..
some pieces of acrylic and led may be beautiful ..

but do not rule out if you suggest something
which can add a longer bow, without abandoning its simplicity ...

very grateful for the advice and attention ..

[davekni]

Appears to be working quite well.  I can't think of any changes to recommend.

[aie212]

thank you dave ..
then .. I will start packing properly

[Mads Barnkob]

I completely agree with Dave. Getting some 25'ish cm discharge from a 12cm secondary coil driven by a single IRF460 MOSFET is a great result and trying to improve on that length is most likely going to end up in shattered silicon

Great job on simplifying the SSTC, but how stable is it? Will it get more and more unstable at higher DC bus voltage? Like flickering discharges, change in discharge sound etc?

[aie212]

Thank you Mads ..

right .. above 180volt start unstable .. mosfet like losing power
although sometimes there is a longer bow ...
I stopped at 180volt .. and I started tidying up
and put it on the table for decoration ..

happy for your correction ..

[Arthur HV]

Hi can you send me the original schematic please

[alan sailer]

aie,

It is a nice looking coil. I would like to build one to play with.

A few questions;

1) The MUR860 diode. The IRFP460 has a reverse voltage protection diode built in according to the data sheet. Why a second one?

2) The 05uF tank capacitor. Is it 0.05uF? That value looks good from a quick JavaTC run.

3) You appear to have four electrolytic caps to the one side of the input choke. What was your buss cap value?

4) There is a cluster of resistors and a blue capacitor attached to the driver board (in the photo). I don't see that in the schematic.

Cheers.