A simple 9 Volt 2 amp supply using a single IC regulator.
There is little to be said about this circuit. All the work is done
by the regulator. The 7809 can deliver up to 2 amps continuous output
whilst maintaining a low noise and very well regulated supply. The
circuit will work without the extra components, but for reverse polarity
protection a 1N5400 diode (D1) is provided at the input, extra
smoothing being provided by C1. The output stage includes C2 for extra
filtering, if powering a logic circuit than a 100nF (C3) capacitor is
also desirable to remove any high frequency switching noise.
C1 = 100uF-25V electrolytic capacitor, at least 25V voltage rating
C2 = 10uF-25V electrolytic capacitor, at least 6-16V voltage rating
C3 = 100nF-63V ceramic or polyester capacitor
IC = 7809 Positive Voltage Regulator IC
D1 = 1N5400 Diode