DC Air Ioniser Help.

Hi all, I don't use forums much so excuse me if I'm clumsy. I'm fairly new to electronics, and it seems I get the theory and physics much better then the practical application. I have an approximate 15KV flyback based power supply that is extremely low current that I wanted to use as an negative ion generator for air. I don't think it's the ideal set up, but I like experimenting to teach myself.

Anyway I used four 20kv diodes for full wave rectification, mainly because it was easier to find four 20kv diodes than one single diode with a much higher PIV, but now I'm kind of stuck. The rectifier works well, and the needles connected to the anode give off quite a palpable 'chill', but I really feel like I've missed something important and glaringly obvious, any help or suggestions would be appreciated. Please excuse my stodgy diagram. Many thanks.

Ok so what is the other side of your HV output tyed to?

Heh heh, yeah that's the glaringly obvious bit I got stuck on. I just didn't know where to put it, or what to do with it. The anode puts out a nice breeze with the cathode ignored, but it seems inefficient to leave it like that. I'm looking for a 'what' to do with it and a 'why' if possible so I can fill in my patchy understanding. Thanks!

We recently started a discussion around this subject that can be found here. If you follow the link posted in that thread you may find some useful information. I don't think you want a full wave bridge on your HV out but a single diode and a few HV caps. Generally for a circuit like this the transformer configuration is different. Anyway, maybe the link will help.

Ron

Heh heh, yeah that's the glaringly obvious bit I got stuck on. I just didn't know where to put it, or what to do with it. The anode puts out a nice breeze with the cathode ignored, but it seems inefficient to leave it like that. I'm looking for a 'what' to do with it and a 'why' if possible so I can fill in my patchy understanding. Thanks!

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Depends on the app. Normaly you would ground it, sometimes back to the input. Andy

Here is one from PS
**broken link removed**

Most of the Ion generators I see are like this one,

https://www.electronics123.net/amazon/datasheet/k57.pdf

Voltage mutlipliers with out a return connectoin. You will have to play with yours to see what works best but I would bet you will need a good earth ground to get yours to work properly. Andy

Thanks. Yeah, it wasn't the ideal set up. I was just playing about with what I had. I was using the power supply (which isn't my design) for digital Kirlian/corona discharge photography, just thought I'd play about with ionised air.
The half wave with capacitors seemed like a better idea, but I gather a single diode for half wave should ideally be about four times the peak inverse voltage of the input (I could be really wrong about that though), which would be about 60 KV, and it's really hard to find really HV diodes, at least cheaply. I could reduce the voltage or split it, but that's getting a bit convoluted and would probably be even more messy and inefficient, I think I'll just make a multiplier like you linked to.
If I attach the positive to a copper tube with the negative to a single sharp needle positioned at the tubes opening, it belts out a lot of wind, enough to occasionally snuff out a candle - but kind of defeats the point of an/ionising the air, as much of the negative charge gets drawn back into the tube. I probably will go with the voltage multiplier. Thanks for the links! I'll play about with grounding too.

I tried to do a reply with quotes, it seems it needs moderating. But you were right, grounding the positive to true ground (plumbing) got it going perfectly. Thanks so much for your help.

(P.S Now I've done that I can see why I needed to do it, which is the somewhat obvious bit I was talking about.)

Micky; Glad to hear you are making Ions. Have fun. Andy

Thanks Andy. There was one odd phenomenon that (also) confuses me. When the power supply is grounded to true earth it is much more apparent, I can't tell if it is from an excess load on the power supply or what it is. It also happened when it wasn't grounded, but to a much smaller degree and also when it is being used AC and a spark is being drawn or used for corona formation.
Basically anything metallic in the vicinity becomes painfully charged. When it's earthed it becomes even stronger and anything within a foot becomes painful to touch with an oscillating sparky discharge. The further away the less it becomes apparent, even the capacitors emit a strange squeal. It ceases as soon as the power is cut, with no palpable residual charge. High voltage is strange, one of the reasons I stick to minuscule current and avoid playing with capacitors. Though when you look about there's a lot of things that could make accidental capacitors...

Yes the high voltage will always try to complet a path anyway it can. Holding it at bay is what gives you the IONs. But if thare is an easier way to ground it will take it. Andy