160mm DRSSTC project

[Benjamin Lockhart]

Looking good! Why not test it at 240V input yet? faster current ramp up and lower on-time usually makes longer brighter sparks with less power.

[Mathieu thm]

Looking good! Why not test it at 240V input yet? faster current ramp up and lower on-time usually makes longer brighter sparks with less power.

Thanks !
When I tested it just before, the primary was too low in frequency, I reduced it by one turn, I didn't push it too hard because I didn't re-adjusted phase lead.

[Benjamin Lockhart]

Since the switching frequency changes throughout the burst, you can only get phase lead set so close to ideal anyway. It doesn't need to be adjusted by much.

[Mathieu thm]

Yes, that's true, but I prefer to check phase lead every time I make a change, just to be sure!

[Mads Barnkob]

Congratulations on your first light!

Great to see all the hard work come to life. Why did you change the primary coil copper pipe to a larger diameter?

Looking forward to FULL POWER videos

[Mathieu thm]

Thanks !

I changed the tube to 3/8" because the 1/4" heated up a bit too much and in midi mode it would have been even worse.
Also because I'd like to test freewhelling on this coil one day.

Can't wait to full power test !

[Mads Barnkob]

I changed the tube to 3/8" because the 1/4" heated up a bit too much and in midi mode it would have been even worse.
Also because I'd like to test freewhelling on this coil one day.

That makes sense, 6 mm is way too small for a coil like this. 10 mm is minimum

[Mathieu thm]

6mm tube is fine with watercooling, but I prefer to avoid watercooling for now. But if one day I test freewheeling, I'll probably need watercooling.

[Mathieu thm]

I needed to lengthen the breakout point because the other was too small, so I needed to retune the primary a little, I think I'm still not perfectly adjusted and think i can ajusted the primary to lower a little the primary frequency.
I haven't had time to test more yet and this is what I've got so far :

Test at 230Vac (325V BUS), 725A OCD and 100µs (interrupter potentiometer is not in perfect condition, that's why the arcs sound strange) :
Sorry for the video quality !

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And another test with another interrupter at 230Vac (325V BUS) 725A OCD and 100-150µs :

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I measured the longest arc at about 1m80.

[Benjamin Lockhart]

This should be capable of quite a bit more. I'd try 680V bus if you can.

[Mathieu thm]

I also think I can do much better, I made a doubler directly just in case, for the moment it is not connected to double the voltage, I will experiment a little more with the primary adjustment, and maybe I will try with 650v BUS.

EDIT : maybe I'll test the 650v BUS tomorrow

[Mathieu thm]

I finally wired the voltage doubler to have 650V on the BUS at maximum, and I did a quick test.
I was able to increase the BUS voltage to about 430Vdc before the OCD tripped almost all the time, so the next step will be to increase the OCD from 725A to something like 775A or 800A and test a higher BUS voltage !

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[Benjamin Lockhart]

When I run my DRSSTC3, The OCD trips almost all the time. It's fine to run it like that. OCD is set to 800A for mine.

[Mathieu thm]

I think my final OCD will be around 800A or just below, I think it will be perfect.
I think I should still be able to detune the primary a little, I am very happy with the results so far !

[paulsimik]

You can see that there's still some tuning to be done. You may have too few turns of the primary coil or a large MMC capacity, that is why the current is high. You can increase the ontime, here up to 200us, instead of increasing the frequency