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GFH

Sun Jan 15 2012, 06:44PM

Registered Member #4324 Joined: Mon Jan 09 2012, 03:16AM
Location: Surrey, BC, Canada
Posts: 35

Alex (or Patrick)

Do you have guys have a thought on whether the number of windings or the gauge of the wire used on the primary makes a difference on the arc?

Going to try heavier gauge (14) (using 20 gauge and 20 windings right now) and less windings and see what happens just wanted you thoughts.

m4ge123

Sun Jan 15 2012, 07:32PM

Registered Member #4118 Joined: Mon Oct 03 2011, 04:50PM
Location: MD
Posts: 140

Your mosfet has way more resistance than your winding so the wire gauge won't make a difference. Less turns should give you more voltage out.

GFH

Sun Jan 15 2012, 09:06PM

Registered Member #4324 Joined: Mon Jan 09 2012, 03:16AM
Location: Surrey, BC, Canada
Posts: 35

Thanks m4ge123

I shall experiment

GFH

Sun Jan 15 2012, 11:55PM

Registered Member #4324 Joined: Mon Jan 09 2012, 03:16AM
Location: Surrey, BC, Canada
Posts: 35

FYI

Tried reducing the windings from 20 to 15 to 10 and as they got reduced so did my arc/volts out.

Patrick

Mon Jan 16 2012, 12:24AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

GFH wrote ...

FYI

Tried reducing the windings from 20 to 15 to 10 and as they got reduced so did my arc/volts out.

The HV out will be a concave down parabola... the wire guage wont matter, but the number of turns certainly will.

As for the parabola, as X increases from 0 turns towards many turns, the Y-axis will equal output voltage, first the output will rise with an increase in primary turns, then with many turns youll reach a plateau, (the top of the concave down parabola.) Then with too many turns youll start seeing the output V start to drop down. There is an optimal number of turns but it varies wildly with each type and maker of flybacks and ampere-turns on the core.

Radhoo and Proud Mary really schooled my ass on using the internal primary, so far the best output ive ever gotten has been attained while using the internal coils.

try 30 turns then 40 and record the arc length... also, i hope you have your two SLA's in sereis, not parallel.

Alex M

Mon Jan 16 2012, 12:36AM

Registered Member #3943 Joined: Sun Jun 12 2011, 05:24PM
Location: The Shire, UK
Posts: 552

Patrick wrote ...

GFH wrote ...

FYI

Tried reducing the windings from 20 to 15 to 10 and as they got reduced so did my arc/volts out.

Is it the same when using a low input voltage? like 12v? every time I tried using internal primary's arcs were always small.

GFH

Mon Jan 16 2012, 12:43AM

Registered Member #4324 Joined: Mon Jan 09 2012, 03:16AM
Location: Surrey, BC, Canada
Posts: 35

Well that's interesting Patrick. Think ill start with 4 and work my way just to see what happens.

I had the batteries in parallel (12v) just to keep the current up. I'll give it a go with 24 and see what happens.

I'm afraid I haven't had much luck finding the internal primaries yet. But I also admit I haven't looked very hard to find them.

I'll try that after I try the windings and voltage. Only want to change one thing at a time.

Thanks guys most educational

m4ge123

Mon Jan 16 2012, 12:46AM

Registered Member #4118 Joined: Mon Oct 03 2011, 04:50PM
Location: MD
Posts: 140

Try increasing your input voltage and number of turns proportionally (if you double your input voltage, double the number of turns).

Patrick

Mon Jan 16 2012, 01:08AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Alex1M6 wrote ...

Is it the same when using a low input voltage? like 12v? every time I tried using internal primary's arcs were always small.

Once you make the decision to use the internal primary, you MUST use the voltage the datasheet specifies, thats the hard part, especially is you dont have the data sheet.

lets look at an example:

follow my logic here:
first, i could use the pins 4 and 8, with 20V for a primary.
second, i can and currently am using pins 6 and 8, notice the phasing sign... that means 85-20 = 65 volts for this one.
third, i could also use the pins 11 and 10 and run them off of 165V.

Now it should be said that we might not have the wire awg visible, so on the low voltage coils we might have to artificially limit the current, since the reactive impedance might be insuffcient.

On that last one, 165V is really close to 120Vac FW rectified to 170Vdc, Te hee

, im going to run it in off wall-socket power soon too.

EDIT: yes i would make one change at a time, otherwise youll blow stuff up and not know why.

GFH

Mon Jan 16 2012, 03:07AM

Registered Member #4324 Joined: Mon Jan 09 2012, 03:16AM
Location: Surrey, BC, Canada
Posts: 35

Thanks Patrick.

Explains why I didn't get anything when I tried what I thought were primaries at 12V :)

These are photos of what i have for a FBT. I've trying to locate a datasheet on it but can't

It's out of a 10 year old 19 colour TV, North America. Model is a Durabrand, obviously re-branded TV of some sort.

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