Gray Tube Replication

[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

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]

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

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

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]

test

hi aaron

thanks for best wishes

i will post pic and vid

have wonderful 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]

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]

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]

reply

hi aaron

i am wating for your reply

please reply

[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

[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.

[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.

[pranav2010]

circuit modification

hi aaron
please tell me will it work ???

you are right i found this Mark McKay collection.

[Aaron]

comments on circuit

Hi Pranav,

I would move the SCR to the negative side of the ignition coil primary.
That way the positive potential of the cap is already inside the coil
when you switch the SCR. On the positive side, the positive potential
has to move into the resistance of the windings. I believe it is also
the standard way of doing it - switching it on the negative.
However, this should not prevent it from working - but I would switch
on the negative.

Your reed is just connecting the trigger of the SCR to ground but you
need a positive potential there. You show Battery + there so I'm not
sure if that is what you mean, please clarify. In any case, move the SCR
to the ground and put the reed across the anode and the gate and you'll
want to put a resistor between anode and reed.

With the SCR, if your cap is not discharging enough on each cycle, the
SCR will not turn off and will remain conducting. From an AC source to your
cap - for example, if there was a full bridge, that SCR probably won't turn
off, with half bridge, the SCR will turn off. With the voltage doubler, I'm
not sure if the cap is able to discharge enough to shut off the SCR. I think
you are getting 120hz (if you are on 60hz) and that may not allow the SCR
to turn off. That has been my experience.

Also, your CDI cap is 200v but I think you should have at least a 400v
cap so you don't blow it up. You have 120uf on the CDI cap and that
capacitance should work but I think that is quite a bit to discharge into
an ignition coil. Again, will probably work at that capacitance because I've
done it with more but since you have 1000v 2uf booster cap, you can use
quite a bit lower uf on the cdi cap. I would do 47uf max and you can
probably get away with as low as 4uf but I'd probably do 10uf~47uf
range for the CDI cap for this application. And charging a CDI cap from
the wall, you may want a serious power resistor between the AC and
ground of cap.

It is optional, but you could put some HV diode(s) from the HV output
of ignition coil to the gap. That would prevent any feedback into the HV
windings from anywhere else.

Your 3 point gap arrangement looks good. Forcing HV to hit LV before
hitting grid point.

On your low voltage source, make sure to use at least a 2kv or 3kv
bridge if you want 1kv out of it. It will let the microwave oven transformer
work easier. Common ground looks good.

On the trifilar, actually only a bifilar is needed. I used a trifilar because that
is what I had freed up. The recovery winding can be in the same direction
or opposite. If you check the last weeks posts in the Renaissance
conference thread, you can see some discussion on the reverse wound
concept. If you do happen to use a trifilar, do NOT connect the 26 and
23 gauge (trigger and power) winding in parallel. This slows the decay
rate of the magnetic field and you want it fast. At least at this point.
There are some interesting properties to paralleled coils but that should
be explored later and not when getting it to run.

Is this the diagram that Mark McKay drew up? Anyway, please make the
above changes to this diagram and let's move to the next step. Show
me the changes and I want to double check it before you try it.

The SCR issue is probably the main reason why it is not working for you.
If you just put that to the negative side, invert it of course, and put
reed between anode and gate.