And in the true spirit of a hacker, he started to notice the patterns programmed into the fake flame repeat over and over again. recently went out to dinner at a restaurant that was using some cheap LED candles (yuck) instead of the real thing. Video after the break.Ĭontinue reading “A Relay-Based Pseudorandom Number Generator” → Posted in Holiday Hacks Tagged blinky, christmas ornament, linear feedback shift register The project also serves as a great way to learn about shift registers and basic relay logic, though the latter is rarely used these days for serious purposes. The result is a cute Christmas ornament that blinks in a deterministic fashion, and has a great old-school look due to the exposed copper of the PCB and the retro LED colors used. built the shift register using relays, which create a lovely clacking sound as the register operates, and LEDs, which glow depending on the values in the register. Thus, the numbers generated are pseudorandom, not truly random, and depend on the initial seed value of the system. The LFSR generates a stream of numbers, with each number dependent on the previous state of the register.

The build relies on a 16-bit linear feedback shift register, or LFSR. built a Christmas decoration that does the latter, displaying the results on an attractive flashing ornament. There are a great variety of ways to build a random number generator, and similarly many ways to generate numbers that appear random, but in a pure mathematical sense generally aren’t.

Linear feedback shift register wakerly