Creating a cheap 400V DC battery which does not give off any mains 'hum'? Answered
I want to create a battery which will be used for powering high voltage circuits such as valve circuits, at 400 Volts DC while also creating as little noise as possible (I want to avoid using the mains due to mains 'hum'). It needs to be a relatively cheap option if it can be helped. Any help/point in the right way would be welcome, Thank you!