I was playing around with some logic gates and they seem to be extremely sensitive.
If I take an AND gate and breadboard it, and put both it's inputs to high(by a jumper wire of about 1.5in), and touch the jumper wire which is sheilded, the output fluxuates ;/ I could understand leaving the input floating but when it's directly jumped to high? Is this normal or something else going on?
What logic family?
If what you are describing was normal, no computer in the world would function. Something is different than you think it is in your circuit. Make no assumption s and look it all over, again. You'll find it, I suspect.
What logic family (and complete part number)?
Any chance that the jumper wires are making intermittent connections when you tough them?
74HCT08
Potentially... I didn't think that maybe there would be minute vibrations that would be enough to cause contact issues... thats the best explination at least
How are you fixed for VCC - GND bypass caps? You should have a bunch of 0.1 or 0.22s on the board.
Tam
Something else is going on. Likeliest culprit is a bad connection on the input. Measure the voltage directly on the chips input pin and see if it really is logic high. Check your ground and power connections on the actual chip pins too, they could be making bad contact. Try the other AND gates in the package. Some trickier culprits will depend upon what logic family you are using.
Dave.
Also make sure that the original poster is grounded, to eliminate static.
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