Octal latch problems
FIRST of all, WOW!--thanks for responding so quickly! I'll answer your questions in CAPITALS:
The first question is... Are you using sensitive gate SCRs?
I'M USING T106 SCR's. I WILL HAVE TO CHECK AT SCHOOL TOMORROW WHAT THE LETTERS ARE AFTER THE "106..."
Further questions include.. What load are you driving, and what is you power source (and how well regulated is it) -- or is it the one shown in the PDF?
THE LOAD IS A 6.V VOLT, 0.15 A INCANDESCENT BULB
THE POWER SUPPLY IS DEFINITELY NOT THE ONE IN THE PDF! THAT'S A LOT OF WORK! I'M USING AN APPLE ADAPTOR (WITH ELECTRONICS INSIDE, NOT JUST A TRANSFORMER 4 DIODES AND A CAPACITOR) I'LL HOOK IT UP TO A SCOPE TOMORROW AND SEE WHAT KIND OF RIPPLE IT HAS (THOUGH I'M EXPECTING, BEING APPLE, IT IS PRETTY SMOOTH...)
What voltage do you measure across the supply rails?
THE NO LOAD VOLTAGE IS 5.0, WHEN I PRESS A BUTTON, I'M NOT SURE--I'LL MEASURE IT TOMORROW IN MY CLASSROOM AND GET BACK TO YOU.
Did the fault start with one channel and spread to the first 4, or did all of them fail at once (was it 2 failure events, or 8, perhaps in 2 groups)?
THIS WILL BE A BIT LENGTHY REPLY: THE BREADBOARDED VERSION, AFTER CONSIDERABLE FAILURES, WORKS PERFECTLY--ALL 8 BUTTONS. THE SELF-DESIGNED AND ETCHED PCB (USING A REALLY OLD (READ: DOS) PROGRAM, EASY TRAX, THAT I DOUBT YOU HAVE THE FILE TO OPEN) ALSO WORKED FINE, ALL 8 BUTTONS, AT FIRST. THEN, AN HOUR LATER, HAVING DONE NOTHING THAT SHOULD HAVE DAMAGED IT, BUTTONS 1-4 STOPPED HAVING THE LIGHT GO ON WHEN BUTTON PUSHED. I TRIED TAKING THE 373 IC FROM THE BREADBOARD AND INSTALLING IT IN THE PCB VERSION, BUT IT STILL DOESN'T WORK.
Are you using the LS part, or did you select another part (say 74HC373, etc)? I SURE THINK I'M USING THE LS PART, BUT, AGAIN I APOLOGIZE, I WON'T KNOW UNTIL TOMORROW MORNING WHEN I GET TO SCHOOL. I'LL GIVE A MORE COMPLETE REPORT THEN.