Ionizer power generator

[JustinP]

Hi all,
I'm making a small air ionizer for a personal project I'm doing. I'm using an arduino to control the circuit, so I just need to safely design the dc power generator and the circuit around it. I've attached a datasheet of a "kation anion generator" that I'm thinking of using (it is from China but they seem to be the main producer of these). My plan is to provide 12 Vdc to the input side, and I'd like to end up with 4-5kv (both positive and negative) at 15-20 mA. The outputs would go to 2 electrode rings (one for positive, one for negative) with a grounding ring about an inch away from the electrode tips (behind a ring of plastic). The electrodes would be about half an inch from each other. I'm a mechanical engineer so I'm a little weak on circuits, and I'm nervous about the high-voltage. I'm figuring on using a MOSFET to turn the circuit on and off using a signal from an arduino. I appreciate any feedback on the design or any safety tips.
-Justin

 

[dr pepper]

You could switch the dc to the ht supply with a relay to keep them isolated.
Is the unit you showed meant for ionizers?
Also at the voltage and current you quoted that would be 100watts, ionizers generally use less than 1, unless your building a power ionizer.
Plenty of decoupling caps across the supply for module and processor are a good idea.

Oh yes welcome here

 

[JustinP]

Thank you very much for the welcome. Sorry! 15-20 mico-amps, not miliamps. The unit is meant for ionizers.

So you suggest replacing the MOSFET with a relay and adding decoupling caps? Thank you, they both sound like good ideas, I'll try to add those to the circuit.

 

[jpanhalt]

Why do you need a bipolar supply?

John

 

[JustinP]

For static elimination. I need to create both anions and cations to neutralize static buildup on surfaces.

 

[dr pepper]

I work in a paper mill, we have machines that do just that, the ones I've had the cover off use cockroft walton multipliers from a low voltage, seperate supplies for pos and neg.
New ones are very posh and come with a sensor so they can adjust themselves.

 

[JustinP]

I've looked at using those, they are cheap and easy to make, but don't they need an AC in? I'm looking at using battery power for this device - very similar to the ionizers used in industry but lower power running off a battery.

 

[JustinP]

I'm attaching the circuit for your review. Please excuse how amateurish I'm sure it is. One thing I'm not sure on, is if I need any diodes, resistors, etc in the circuit, and exactly where the decouplers would go. I appreciate any feedback on the circuit.

 

[alec_t]

I don't like the idea of driving relays directly from the Arduino pins. I'd add transistor drivers for the relays, plus reverse-biased diodes across the relay coils for back-emf protection.

 

[JustinP]

I can do that, but would this work as an off-the-shelf solution: **broken link removed**
It seems to have some diodes on it, although I'm not sure if they're for back-emf protection

Also, using the power supply I've provided the datasheet for on the top, is there anything I should add around that portion of the circuit?

 

[alec_t]

If that relay module is a tried-and-tested device it's reasonable to assume it has back-emf protection; otherwise the seller would have a lot of annoyed customers . The relay ratings look ok for switching a small 12V fan.

 

[dr pepper]

The one I looked at indetail uses 12v dc, and a full bridge to switch that into the bottom of a voltage multiplier, I expected high voltage into the base but its low voltage dc.

You could put some arc suppression across the relay contacts, assuming they are mechanical contacts, a 100 ohm and a 100nf class x, you can get proper suppressors with those 2 built in.

 

[JustinP]

I've attached a revised drawing based on your comments. I'm not sure about the decoupling capacitor values, or if there's anywhere else I should place them.

Pepper - I'll look at the dc voltage multiplier option - that maybe a better route.

Please let me know if anything is incorrect (very likely) or if there's anything else I should add.

 

[dr pepper]

Looks ok initially, you'd have to see if theres any trouble when running it.

 

[JustinP]

Sounds good. Thank you very very much for all the help guys.