how to build 7v transformer less DC output

 

Please read the User Agreement.
When you read point 6 the topics that are not allowed are summed up there.

 

You have just bumped into one of our hard core rules. AAC mains to low DC must have an isolation transformer to be safe. The little USB type power supply cubes use a torrid transformer. We are willing to discuss this in detail. But if you insist on no transformer this thread will be closed as a safety issue and a Terms of Service violation.