Circuit Breadboarding

When cinstructing logic circuits, care should be taken to ensure that the parts are not damaged while braedboarding the circuit. Carefully insert the IC into the breadboarding socket so that the IC is stradding the center groove on the socket. Make sure that both rows of pins are correctly lined up with the holes in the breadboard. Be careful to avoid bending the IC pins anymore than necessary. The ICs can be safely removed by prying up each end with a screwdriver (or similar tool) or an IC puller. Do not insert or remove ICs with the power applied to the circuit.

A notch or dot at one end of the IC package is used to locate pin 1 of the chip and the pin numbers then increase in counter clockwise direction around the device as viewed from the top (see Figure 1). Inserting all ICs with the same orientation for pin 1 will facilitate circuit wiring  and troubleshooting.
 

 
 
 
Figure 1: IC pin numbering for 14 and 16 DIP packages (top view).

Determine the pin-out information for each chip by consulting a data book or sheet for the device. Notice that power and ground, inputs and outputs are sometimes located on different pins for different part numbers. Label the pin numbers for each device on a logic circuit schematic to aid in wiring the circuit and in troubleshooting it later if necessary.

Systematically and carefully wire the circuit wire the circuit with the power off. Electrical connections are made to any pin by inserting wires into the holes that line up with that pin. Wiring errors are the most common source of circuits failure in breadboarding circuits. The jumper wires used to connect the circuit components together should have 1/4 inch of the insulation stripped from each end of the wire to avoid inadvertently shorting the the wires together. Using short jumper wires will facilitate troubleshooting later if necessary. Double check the wiring against the schematic diagram.