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Digital integrated circuits I
OR and NOT gates combined
In the same vein as the last circuit, Figure 10.38 shows a circuit
combining different types of logic gates — this time an
OR gate whose inputs have been inverted by NOT gates. The
outputs of both NOT gates (hence, also, the inputs of the OR
gate) are measured with two LEDs, while the OR gate output
is measured with the third LED.
Figure 10.38 A circuit to investigate OR and NOT gates
Figure 10.39 shows a breadboard for the circuit for you to
follow. Figure 10.40 shows an incomplete truth table for you
to record your results of the experiment, while Figure 10.41
is a complete truth table, which — if everything goes as it
should — your results will be identical to.
If you’ve already been thinking about this, you’ll no doubt
already have been flicking back through this book’s pages to
locate which truth table Figure 10.40 and 10.41 are identical
to. If not, or if you simply haven’t found it, it’s the truth table
in Figure 10.29 — which is that of a NAND gate.
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