Ok, well maybe the title isn’t entirely accurate. I am a big fan of binary clocks and even own one. They are cheap from a circuitry standpoint. Say I have the time in BCD. BCD stands for Bindary-coded decimal, which uses 4 bits of binary for one decimal digit. For example 0001 BCD is 1 in decimal, and 1001 0001 0111 BCD represents 917 in decimal. For those lost and don’t know how to read binary, going from left-to-right, the first place represents 8, second 4, third 2, fourth 1. If that place has a “1″ you add the number associated with that place. So 0011 is 8*0 + 4*0 + 2*1 + 1*1 = 3. Now if the clock circuitry outputs the time in BCD (which has several advantages, one being easier to read by humans), you need to convert this number so that it can be displayed correctly on a conventional digital clock. We might use a Seven-segment display, in which case we need to determine which parts of the display need to be active for what number. For a binary clock, you don’t need to do this conversion. All you need to do is hook up each bit from the BCD to an LED and there’s your binary clock! The reason why I’m blogging about this is because we were making a BCD to seven-segment converter and my lab partner mentioned that a binary clock is a normal clock minus the converter. That’s why binary clocks are cheap, but still worth buying.