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Use the following steps to complete the wiring of the breadboard

  • Select your circuit. If this is your first time, choose the SR NAND or SR NOR.
  • Operate the switches in the circuit simulator. Read the description of the circuit if you need additional information.
  • Using the schematic, wire up the circuit in the breadboard simulator. When a wire end is placed in a socket of the breadboard that corresponds to a node on the schematic, the respective node of the schematic will turn red.
  • If a correct connection is made, the wire ends will snap into the socket.
  • Note that all the VCC (red wire) and GND (black wire) connections are already done.
  • When all the nodes are wired up, a red LED will light up near the VCC/GND terminals.
  • You may now operate the breadboard switches and observe the LED results.
  • When you wire up the circuit using a real digital trainer, do remember to wire the VCC and GND wires and power up the digital trainer.
  • You must login using your facebook account to save or restore the breadboard connections.
  • Click to close any of the panes (breadboard/schematic/description/help) and click on the corresponding menu item to open it.

If you are unfamiliar with the breadboard, there are many resources available online that explains how to they work.

24h Digital Clock Circuit Design Using 7493

This circuit shows the implementation of the hours portion of a 24H clock

The 4 blocks of a digital clock are

  • 1 Hz clock generator to generate 1 PPS (pulse per second) signal to the seconds block.
  • SECONDS block - contains a divide by 10 circuit followed by a divide by 6 circuit. Will generate a 1 PPM (pulse per minute) signal to the minutes block. The BCD outputs connect to the BCD to Seven Segment circuit to display the seconds values.
  • MINUTES block - identical to the seconds block it contains 2 dividers; a divide by 10 followed by a divide by 6. Will generate a 1 PPH (pulse per hour) signal to the HOURS block. The BCD outputs connects to the BCD to Seven Segment circuit to display the minutes values.
  • HOURS block - the 24hr clock will have a divide 24 counter. For 24H, it will count from 00 to 23 hexidecimal or 00 0000 to 10 0011 binary before resetting to 00 0000 and repeating. Click on SW7 and observe the LEDs.
  • The ones circuit (IC1) is connected as a 4 bit ripple counter whereas the tens circuit (IC2) is connected as a 3 bit ripple counter. For IC2, the CLK signal is connected to CKB rather than CKA in IC1. We leave it to the reader to figure that if IC2 is connected as a 4 bit counter like IC1, the tens will increment by 2 rather than 1. Please see digital clock for more information on the 7493 connections.