8 LED Cube ( NO Microcontroller )

This simple "Led Cube" circuit generates a random sequence without the use of microcontrollers. It uses a shift register in a configuration called Linear Feedback Shift Register ( LFSR ) .

You can arrange the LEDs in any any other configuration you like.

IC1: CD4001 ( cmos quad nor gate )

IC2: CD4015 ( cmos dual 4 stage shift register )

IC3: CD4070 ( cmos quad XOR gate )

LED 1-8: any color, any size LEDs.

enables the 1Mhz oscillator for 150uS (150 microseconds)

This circuit generates random numbers. It is also often used to generate white noise ( a sea-wave type of sound ) which contains all audio frequencies in equal levels. Can be expanded by adding more stages.

If all stages are "0" the LFSR will lock in that state. These 2 components will prevent this by inserting a "1" into stage 1 if this happens.

Leds are driven directly from CD4015 outs through current limiting resistors. Value is not critical.