Anyone capable of metal spinning?

[Sigurthr]

Ahh, brilliant way to get around the need for a precision burst controller and over-current detection. Half bridge inverter section I assume since you said pair of igbts.

What's the interrupter frequency and duty cycle range?


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[Things]

Ontime is usually around 400usec or so, BPS I'd keep under 10 or so. It can go higher, but higher than that and the transformer starts running out of time to recharge the caps before the next burst, so your streamers start diminishing. Alternatively you can bring the ontime right down and increase the BPS rate for higher frequency, but smaller streamers.

I like the design because it's a lot safer than having "unlimited" mains potential behind it. If you accidentally leave the IGBT's on too long, you just overload the transformer and pop a fuse, everything else is fine, and if you somehow come into contact with the tank, you'll take the initial brunt of the caps, but after that it'll pretty much be a strong tingle

The original coil didn't have any way of external control, I ended up just tapping into the gate drivers inputs which allowed me to use an Arduino to control it - apart from that it just had 2 modes, one was just a single shot, 2BPS mode, and the other would fire a few shots in succession with a longer break.

My design I'm planning to use a uC for the main control instead of discrete timers, and I'm probably going to build in an IR receiver so you can have a truly isolated remote control

 

[jeffreythe00]

I guess you could contact jeffreythe00, he has built many coils! :beer:

Jim

I think you have me mistaken for someone else.

 

[Sigurthr]

Yup excellent design. I'm glad you're going with a designed in (as opposed to hacked like the original) variable interrupter.

What range of bps are you thinking of going with? I'd suggest 1-60 at minimum so you get strong streamers and mains synch.

Shield that uC well and use lots of rf bypass and decoupling caps. I learned this well with my uC interrupter (you're more than welcome to copy it if you like, it's open source).

If I have the money for it when this becomes available I'd certainly love one.


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[Things]

I'll have to do some testing once I build myself a prototype version to determine what ontime and BPS rates I can get away with. I'll be going with an external panel mount fuse, vs an internal fuse on the original, so even if you accidentally set the ontime too high, just pop a new fuse in. It's designed to be basically an indestructible coil in terms of control, it'll run all day long with only a 2x2x1cm heatsink on each of the IGBT's (popular 60N100's) and barely get warm.