I need to find a way to turn 12 or 24 volts dc into 90 volts dc.Is there a way to do it?

 

Hello,

For converting 12 or 24 Volts into 90 Volts you will need a step-up inverter.
Take a look at this page, where a lot of these are shown in the PDF's
http://www.maxim-ic.com/cookbook/powersupply/

Greetings,
Bertus

 

Ronald Dekker's page on Flyback Converters is a very good tutorial on how such things work, and how to get started making your own inductors:
http://www.dos4ever.com/flyback/flyback.html