Well done! Unit looks great. Please keep us informed of how well it works.

Did you do a test of coating using the corona discharge preparation versus coating without the preparation?

You have set me thinking of alternative High Voltage sources that are readily available.
-Neon sign transformer with a rectifier on the output. (5-30kV).
-A car ignition coil with a driver circuit
-A corona module from an older scrapped photocopier. (The one I have is 5kV)

Emulsion.

Quote Originally Posted by hrst View Post
I have now built a working corona discharge unit in order to try subbing polyester (PET) sheets, to prevent the emulsion from loosening during processing.

It consists of 24V DC supply, a HV source made from flyback transformer (from color CRT television), one power transistor and two resistors. Transistor's base current is taken from feedback winding and it starts to oscillate, generating 5 kV voltage (measured at 0.6 mA current). The complete unit also contains a meter for current (0 - 1 mA).

High voltage + is then fed to a corona wire taken from a copier, and ground is connected to a copper plate under the corona wire.

A PET sheet is placed on the ground plate. Push-button is pressed to enable HV, and then you drag the sheet.

This seems to work: the sheet is heavily attracted by the ground plate and it needs much force to drag the sheet, when the button is pressed. During this, unit produces quite loud hiss noise from corona discharge and draws HV current of 0.2 mA, making the total corona power of 1 Watt at 5 kV. And a familiar ozone smell like with copiers & laser printers.

I made some coatings on corona-charged sheets. I coated them in a few minutes after coronizing. I will post the results in a few days after they have dried&hardened so I can try to process them.

I attached some images of this cool unit .