multiple volt power supply:

click here to enlarge the schematic

parts:

U1	LM7812 +12 VDC Voltage Regulator
U2	LM7912 -12 VDC Voltage Regulator
U3	LM7805 +5 VDC Voltage Regulator
U4	LM7905 -5 VDC Voltage Regulator
BR1, BR2	4 amp bridge rectifier
T1	25.2 volt, 3 amp center-tapped ac transformer
T2	18 volt, 2 amp center-tapped ac transformer
F1	5 amp slow-blow fuse
S2	SPST toggle switch
C1, C5, C9, C13	2,000 uF electrolytic capacitor, 35 volt min.
C2, C3, C6, C7, C10, C11, C14, C15	1 uF tantalum capacitor, 35 volt min.
C4, C8, C12, C16	100 uF electrolytic capacitor, 35 volt min.
MISC.	fuse holder, heat sink for voltage regulators, binding posts, ac cord with plug, chassis

all capacitors are 10 percent tolerance

Please operate caution when building this power supply. It is run on standard 117 ac current - and under the right circumstances 117 ac can kill you. Use a plastic enclosure if possible to decrease chances of short-circuiting. Don't use the power supply if it's wet, and never run it without the specified fuse.