hi Jeffrey,

some practical design of ballanced power suply are not even use trafo with CT, because the trafo it self has several output voltage. Say 0, 3, 6, 9, 12, 15 and 18 volts.

So if u want to have +5V and -5V regulated power supply, u can use three outputs of the trafo connected to the voltage regulator ICs (i use lm7805 and lm7905 for positive and negatif outputs respectively).

Since the regulator ICs input minimum is 7.5 volt, you can use 9 volt output of the trafo as CT, 0 volt pin as -9 volt and 18 volt pin as +9 volt irregulated voltage.

Pair of bridge diodes can be used before connecting to input of regulator ICs.

may this helps you...

regards,
fahmy