A technician breadboards a logic circuit for testing. As she tests the circuit’s operation, she finds that many of the FFs and counters are triggering erratically. Like any good technician, she checks the V_CC line with a DC meter and reads 4.97 V, which is acceptable for TTL. She then checks all circuit wiring and replaces each IC one by one, but the problem persists. Finally she decides to observe V_CC on the scope and sees the waveform shown in Figure 8-57. What is the probable cause of the noise on V_CC? What did the technician forget to include when she breadboarded the circuit?

Figure 8-57

Vcc 1 4.97 V 1.3 V