The circuit of the figure can provide voltages of 5, 8.9 and 12.5 V at its output, all doing this from a fixed 5 V voltage regulator. The maximum output current is 1 ampere and the integrated circuit Voltage regulator must be fitted with a good heat radiator, especially if the reader wants to work within its current limits. The zener diodes are 400 mW and the input capacitor must have a higher than the input voltage. The output capacitor can be 16 V.