Oracle

CD4049UB

Speak clearly to the Oracle, ask it any question, and it will answer! You’ll get an answer, that’s for sure, but there’s no guarantee you’ll get the right one! This is a simple yet surprisingly entertaining little project which gives Yes/No answers to spoken questions. The intention is that the answers are largely random, but far too often the answer is consistently dependent on what is spoken. I could have sworn at one stage it was a ‘Bee’/’Bah’ differentiator!

Oracle schematics

The circuit uses just one IC – a CD4049UBE unbuffered hex inverter. The first inverter is simply a linear amplifier to raise the signal level from a condenser microphone. The next two inverters form a hysteresis element (Schmitt trigger) which remembers the last large excursion (positive or negative) of the last utterance of the question. The fourth inverter is a simple buffer, and the last two inverters are timers which extinguish the LEDs while the question is being spoken.

Oracle

The circuit board in the picture was mounted onto the rear of a battery box to hold four ‘AAA’ batteries. A balance adjustment is provided which permits the relative frequency of ‘Yes’ and ‘No’ answers to be controlled a little, though some questions consistently give the same answer no matter what the balance setting (should I read something into that?!!!)

Remember – it’s a silly novelty so don’t get too spooked by it!

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