In this post we study regarding what is corona effect and how to make a corona effect generator circuit at home using a CDI coil and a tesla coil configuration. Then idea was suggested by Mr. Sanjoy
Corona Treatment for Paper Coating
Dear Swagatam Sir,
Many many thanks for posting the alternate switching timer circuit as requested. Although I haven't tried yet, but your circuits work mostly.
Here us another request . In our paper coating lab, we are trying to coat OHP polyester sheets with the same formulation as paper coating.
But the problem we are facing is the low surface tension of the polyester sheets. The applied coating isn't spreading evenly and forming droplets as well. To overcome this problem we need a handheld Corona Treatment device.
Which will be able to produce high density concentrated corona along the edge of a 15 inches long ideal discharge line. It will be better if the circuit can be designed transformer less.
Please advice regarding the design of insulated handle as well. The device will be turned on and swept lightly and slowly over the surface of the polyester sheet from a very close distance.
This way the corona bombarded surface will have higher level of surface tension and can be coated properly.
The Circuit Design
A corona discharge effect can be generally visualized in darkness around high voltage sources ranging from 2kV and above.
The corona effect is created by the emission of ions from a high voltage source due to the immense voltage pressure from the source.
The high voltage pressure causes charging up of the air atoms around the conductor forming a shining crown like structure, hence the name "corona"
This basically happens due to the absence of a neutral or ground nearby, which causes huge electrical pressure build up around the source forcing the air around it to charge up into ions. However if a ground or a neutral line becomes available somewhere within the reach of the source could normally cause the high voltage to jump across the gap giving rise to sparks and arcing.
A practical example of corona discharge could be seen around high tension overhead wiring which normally carry many kVs of potential, the same could be also witnessed around flyback transformer cable used in old vacuum tube TV sets.
A small scale model of corona effect generator circuit can be built using any high voltage generator circuit.
I have discussed an air ionizer circuit in one of my earlier posts, the tip of the needle connected with the circuit could be seen with a tiny blue corona discharge in complete darkness, especially when we hold our finger little above the needle point.
A full fledged corona discharge could be probably built using a CDI coil circuit in conjunction with a small tesla coil.
A CDI coil circuit can be built from the many relevant links provided in the website.
Once the CDI coil circuit is built, the output of the CDI coil could be configured with a homemade tesla coil circuit for visualizing a breathtaking corona effect in darkness.