Air Ioniser circuit

Posted on Oct 21, 2012

A basic mains driven Cockroft ladder high voltage generator is shown in the schematic. This is functionally the same as a project in Electronics Today International many years ago. The peak mains voltage of 340V appears across each capacitor and this is negative with respect to mains neutral and the surrounding environment. The orientation of the diodes defines the polarity. As the capacitors are in series, the voltages sum and at the top of the ladder about 7kV is present. A high value resistor is used at the output end to current limit the output. It is important to use a high voltage rated resistor or a string of lower voltage ones in series, so that the resistors maintain their stated resistance value. This design is for 220 to 240V mains power and a double length ladder would be needed for 110V supply.

Air Ioniser circuit
Click here to download the full size of the above Circuit.

If a single dressmaking pin or other sharp point is connected to the EHT output you will be able to feel a slight breeze of negatively charged air molecules coming from the end of the point. The high charge density at the sharp point causes this ionisation and the negative ions are then repelled from the negatively charged pin, causing this ion breeze. You can also hear the point emitting a slight hiss and in very dark conditions you can just see the point glow slightly. The ionisation at the point tends to physically degrade it over time and this reduces the ionisation occurng there. Some commercially available air ionisers have precision shaped points of special alloys to counter this. One fun way to make sure that your ioniser is still ionising is to use the ion breeze thrust from the needles to spin a rotating emitter pair. A12cm long piece of stout copper wire is soldered into a 4mm plug and this is plugged into the EHT output. The top end of the wire has an ordinary steel dressmaking pin soldered to it. This is the point on which the spinning emitter arrangement balances. A section of aluminium foil about 20 cm long and 6cm wide is folded multiple times down its length until it is about 20cm long and 0.5cm wide. This gives the foil more strength. Try not to leave any sharp edges or points as these may ionise the air in unwanted places on the structure. If you can find a thick aluminium foil pie-tin then this is...

Leave Comment

characters left:

New Circuits



Popular Circuits

Luxeon Star LED driver with MAX1709 IC
High power control for sensitive contacts
Simple voltage controlled oscillator
DIY Tremolo Effect
The simplest digital LCD voltmeter with AVR
power-amplifier 2
16w bridge amplifier using lm383
hv generator circuit
A long-wave SWR meter
Basic gate function
KD-1001 produced by lantern controller
Tape monitor the direction of movement