Gray Tube Replication

[Aaron]

revision

Pranav,

Your cdi power supply - with full bridge, your scr probably won't turn off,
start with half rectification. And you may need some power resistors on
the negative coming off the bridge to limit the current.

You also need HV diodes from the primary + to the HV +.

Remove the capacitor that the HV output is connected to. If you do not
have enough punch, that cap will eat up everything and it will not jump
the gap. You can try to add that later but leave it out for now.

Make sure your bridge from the MOT is a 2k or 3k bridge.

Make your points geometry just like in the Mark McKay drawing. You MUST
force the HV to hit the LV before it can go to the load/grid point.

Please redraw it with the above changes and I'll look at it.

[Aaron]

@Pranav

Pranav,

This will work - this is virtually identical to what I did.
Now of course, your goal with this setup is not efficiency at
the moment but to learn the method first.

For the capacitor charger on the front end, I would move
towards an off-the-shelf CDI and add the HV diodes in the
right direction according to the polarity of your ignition coil.

If your coil has a negative polarity, then reverse the HV diode string.

[pranav2010]

modification

hi aaron

thanks lot

i use 25 amp 1200 volts scr

16uf means i use 2uf 2kV caps 8 in parallel

i use all high voltage diode 1x3

i wrote all details of my circuit on diagram please tell me is every think is ok

one more time thank you

[pranav2010]

reply

hi aaron

i am wating for your reply

please reply

[Aaron]

Pranav's circuit

Hi Pranav,

The circuit looks correct. 16uf looks pretty big but should work.

What size wire are you using for an inductor? What are all the dimensions
of it, turns, etc...? Core diameter/length, etc...? On a few of my tests
when I went too much on the voltage, I was sparking through the
insulation.

[pranav2010]

electromagnet

hi aaron

i am trying to build 9 stator 3 rotor setup.

my coil is 125mm length and it has 1000 turns of 27 awg
my core is transformer lamination it is "I" shape 40mm*50mm size

tomorrow i will test the circuit i will post video on our thred

what do you think is everything ok????????

thanks for reply

have a great day

[Aaron]

good luck on your test!

Hi Pranav,

Good luck on your test! 27 sounds a little small but you can try it out.

16uf at 1000v would be quite a punch. if you have 1000v at a couple uf,
might be a safer test.

Anyway, sounds like you know what you're doing.

Looking forward to some pics or vids!

[pranav2010]

test

hi aaron

thanks for best wishes

i will post pic and vid

have wonderful day

[pranav2010]

power resistor problem

hi aaron

i am using 100 ohm 10 watt resistor but while turning circuit on resistor getting heat and after few second it will bust

your circuit is workig very well but problem is resistor

now i am going to use 100 ohm 100 watt

what do think will it work properly

please reply

have great day

[pranav2010]

power resistor

hi aaron

can you tell me what is the value of your resistor ?????

have wonderful day

[Aaron]

power resistors

Hi Pranav,

I used eight 10 ohm resistors. They were
in series and parallel. So 2 in series was 20 ohm
and I had 4 of those in parallel. I think the
watt rating of them were 100w.

It is possible they were 100 ohm resistors, I'll
check later. In any case, yes, they will get hot
and melt the solder.

I have some really large inductive resistors that
are 10 ohm 250 watts and I would use one
of those if I charged from wall power again.

Do you have access to an off the shelf CDI for
auto ignitions? If so, you can charge the cdi cap
from that and have that cdi connected to a car
battery with no problems.

I charged a cap from the wall for simplicity sake
so I didn't have to build a real circuit.

But if you have a CDI, that is preferable. The CDI
will have a cap around 4uf and 400~600 volts,
which is usually not enough to get the effect with
the booster caps. However, with the diode from
primary to HV on ignition coil you are getting plasma
two times.

One is a small plasma burst from the CDI + diode
setup and the other is to mix that with the booster
cap. So you're using a smaller plasma to trigger the
larger plasma.

The other reason I used wall supply was because
the cap was 47uf, which is more than 10 times the
size of one in a CDI unit and wanted to make sure
it was instantly charged at any speed. Again, the
wall was for convenience but I'd use a cdi if I did
it again.

[pranav2010]

power resistor

hi aaron

i am also using wall power to charge my cdi cap 47 uf. i mix low vol with the high vol i put diode primary + to secondary + just like you

now I am thinking about power resistor I am going to use 10ohm 250watt

is this ok ?????

have wonderful day

[Aaron]

@Pranav

Hi Pranav,

The 10ohm 250w should be ok. I really don't know what the difference would
be from my 110-120v wall compared to your ac wall supply - if you have
220-240v?

Anyway, it should work.

Your diodes should work too but it depends on the polarity of your
ignition coil. If the hv is negative then you need to simply reverse the
diodes from hv to primary +.

Looking forward to your test!

[pranav2010]

power resistor

hi aaron

10 ohm 250 watt are not available so i am trying 10 ohm 100 watt

today i am going to test it

i will tell you the result

have wonderful day

[Aaron]

@Pranav

Pranav, I hope the test goes well!