Another Insanity question.

[digi2t]

Hi all,
I've been drawing up a vero version of the Insanity Box, and I noticed on schematic that it states to ground any unused inputs in the 4049. Yet, on the 2 PCB layouts that I've found, the traces supply +9v to the unused outputs. I'm assuming that since this chip is inverting, that +9v to the outputs is the same as -9v to the inputs?

Just checking to see if my deduction is correct... or if I'm completely out to noobs lunch 

Thanks all,
Dino

PS. The vero is complete, but not verified yet. I posted it in a previous thread, but the image quality sucks. I'll repost it once I can get a better image out of the Ver.3 of DIYLC.

[PRR]

> it states to ground any unused inputs in the 4049.

It should say: do SOMEthing SOLID with un-used inputs. They are like dogs. If you let them wander around loose, they WILL get into trouble. In CMOS, they may howl supersonically, or they may wander to a middle voltage and run hot. In digital logic, such things can lead to unexpected logic; in audio maybe strange noises and maybe nothing bad.

Jam them high or low, whichever is more convenient; makes no difference.

Whether inverting or not makes no difference: just get them to one extreme or the other so they "stay".

[digi2t]

Thanks for the fantastic visual Paul. I figured SOMEthing was up with the - input/+output deal, but I don't have the formal training, or experience (yet) to put my finger on it. Hence I remain, as always, a faithful student to this forum.

I wish I had teachers like you growing up. I probably would have achieved more in life, rather than being just another over-paid public servant 

Cheers Paul,
Dino

[digi2t]

Paul, come to think of it, I recently put together Tim Escobedo's Digital Octave Fuzz. It uses a CD4070 CMOS chip. Should I have tied off the unused inputs (high or low) on this chip as well? I know John Lyons has messed around with this circuit (the XORUS), but there is no mention of whether the unused inputs should be tied off. I haven't had any "mad dog" problems, but I would like to know if this pertains to all CMOS chips.

Cheers,
Dino