This astable multivibrator uses two NAND gates of the 4 available on the 7400 TTL integrated circuit. Two LEDs are used to view the status or logic output of each gate.
LED Sequencer using 4017 Decade Counter (LED Chaser). This circuit has 10 LEDs connected to the decade counter outputs. LEDs light up in sequence. Only one LED is ON at a time
Clock signal generator using 7400 IC. This clock generator is an astable circuit which uses the TTL 7400 (four 2 inputs NAND gates) integrated circuit. Suggested Printed Circuit Board (PCB)