How to change DC 19Volts 4.7 amps into 5Volts 1 amp?

I'm trying to build a iphone charger station with a laptop charger that gives me a output of 19 Volts and 4.7Amps. I know that the typical iphone charger needs to have a output of 5Volts and 1~1.5 Amps… I will be using a 7805 linear voltage regulator but i seem to be burning them out or the capacitor blows up… Is there a way to convert the Voltage and Ampherage?
PS: the finished product will be a USB charger in a amplified speaker set with a nightlight
so I need 5Volts 1Amp for the charger AND the speaker system.
(the USHIO ESP halogen lamps give off a nice dim glow at 19Volts and 4.7 Amps)
can anyone help?

7805 is rated for ONE amp, and that's only possible with infinitely large heat sink. Under usual condition with normal sized heat sink, 750mA is probably the safe output. If you connect 19V input to it, it will generate HUGE amount of heat. 19-5 = 14. 14 * 1 = 14. So it will have to dissipate 14 watts worth of heat at 1 amp load. That's not possible… So this is really a bad way to go.

If your capacitor is popping, you either have a capacitor with too low voltage ratings, or 7805 is going into oscilation. Because its internal gain is so high, 78xx series regulators are known for oscillation. You have to have something like 0.01 to 0.1 microF capacitor very close to the chip, and 4.7 to 10 microF capacitor close to it. That will sufficiently suppress oscillation.
You could use DC/DC converter and make more efficient use of the power source. But if you have to ask this question, this is well beyond your ability at this moment in time.

Linear regulators like 7805 or anything 78xx and 79xx series simply drops voltage and dissipate the difference as heat. It doesn't make use of that wasted energy. So it's really a bad choice to have 1) such a high input voltage and 2) such a high voltage drop.

For you, I would suggest similar voltage regulators but one with 5amp capacity. I forgot the part number but such thing does exist. Use a large heat sink and use a power supply that is around 9 volts, not 19 volts.

You are better off with a DC-DC switch-mode converter. It might be possible to use a car USB charger if the input voltage tolerance is high enough.

Look on ebay for a "5A constant current voltage step down driver module" or something to that effect. There are LOTS of them for very little money. I can't guarantee they will work for you, of course. But they do use an IC designed for efficient delivery of the power you want to provide. If the design and parts are selected correctly, it should work okay. But these are from overseas. So I can't tell you what to expect. You can also find them on ebay with built in display modules, as well. (There are adjustment potentiometers which appear to allow you to tweak the voltage output.)