BabyGeezer:
Rubbish.
You can quite happily connect a logic gate’s input to ground.
Have you ever worked with logic gates? I suggest you review that entire post and have a think about it.HAH!
i'm a n00b about to start something similar and even i can say "removing 5V wires for a low" is not accurate.
i'm going with a cheaper setup of Logic gate chips; 4011, 4071 and 4081 - and HIGH/LOW is just a matter of connecting (pulling, or whatever) an input to EITHER the Vcc(?) (for HIGH or a '1') or to GND (for LOW or a '0').
OK, guys...let me esplain... First of all, what I meant by removing 5V wire for low is this: if you look at jorgeguberte's diagram, you'll see that he has, on each input, a wire going from the input, to +5. ALSO, there's a 10k resistor going from the input, to ground. SO, if you remove the wire going to +5, the 10k resistor is still there, pulling the CMOS input low. Thus, removing a +5V wire, in this case, is a way to cause a LOW condition.
And, in a later post, jorgeguberte states that he "instead of leaving the inputs connected only to the pull downs, i connected the inputs directly to ground in addition to the pull downs." he/she doesn't say anything about removing the wire that goes to the +5 line -- so, I was thinking that maybe jorgeguberte was doing his direct to ground hook-up, WITH THE +5 WIRE STILL IN PLACE. That would, of course, cause a short to ground. And since the +5V line is being supplied by the Arduino, this short would put the Arduino's regulator in short-circuit-shutdown. And, episofacto, that would behave JUST LIKE AN AND FUNCTION -- thus giving jorgeguberte a false positive.