21zp4a crt sub

[kf4rca]

A 7812 will not regulate with an input of 9V. If you want 5v output I would use a 7805 regulator. They also make 7806 and 7808 and I think 7809 regulators along with 7815 and 7824 regulators. You can use an LM317 as a variable voltage regulator. You should be able to find some circuits on this here web.