Pulse Width Modulating incandescent lights and motors is entirely different pulsing LEDs. Lights and motors have a delay factor that averages the pulses. LEDs do not. They have instant response-time.
Look up multiplexing LEDs and see the results.

Originally Posted by colin55

By increasing the current 25% and turning a LED on for 25% of the time, produces the same brightness as a constant current but draws less than 50% of the current.

Hmm. Maybe I will look into doing some PWM flashing. But for my first project I think I will keep it simple.

Originally Posted by audioguru

It is a stupid circuit because it has nothing to limit the current so the LEDs will blow up.
The transistors amplify the current:
1) The current from the 555 into the base of the 2N2222 transistor is limited by the 1k resistor to about 5mA.
2) With a 5mA base current then the emitter current of the 2N2222 transistor is about 600mA.
3) With a 600mA base current then the collector current of the 2N3055 transistor is about 8A.

Sorry. I should have explained it better. The LED array has resistors built into it. That circuit is just to power the LED array.

Using a Hex schmitt trigger IC is no more involved than using a 555. And you don't have the wasted 10mA taken by the 555.

Originally Posted by colin55

"With a 600mA base current then the collector current of the 2N3055 transistor is about 8A."

This is not true.

The current into the base of the 2N3055 is limited to the current taken by the load in the circuit under investigation.

Could you explain how the circuit is working then? It is really throwing me for a loop. Transistors in general just confuse the heck out of me.

Originally Posted by audioguru

Voodoo,
Please learn about PWM if you want by looking for Pulse-Width-Modulation in Google.
It is used for dimming lights and for DC motor speed controls.

I read up on it a bit. I think I understand it a lot better now.

Originally Posted by colin55

Using a Hex schmitt trigger IC is no more involved than using a 555. And you don't have the wasted 10mA taken by the 555.

That may be. But I have a lot more to learn about PWM before I would feel comfortable building a circuit designed around it.