The following instructions will allow you to build a practical test tool for troubleshooting and analyzing digital and microcontroller circuits. The complete Assembly and Instruction Manual can be downloaded from the the following web link:Don's Projects
Step 1: Bill Of Materials
Here's the components needed to build the Logic Probe shown in the Bill of Materials (BOM) picture.
Step 2: Logic Probe Circuit Schematic Diagram
Here's the circuit schematic diagram for the Logic Probe.
Step 3: Adding Resistors
Add the 1K and 330/470 ohm resistors onto the pcb and solder.
Step 4: Add the (2) Capacitors
Place the (2) 150nf (0.15uF) capacitors onto the pcb and solder.
Step 5: Add battery clip, battery, 7 Segment LED Display, and Hex Inverter IC
Add a 5V Voltage Regulator IC, (2) 14 Pin DIP sockets, the Hex Inverter IC and the 7 Segment LED display components onto the pcb and solder them.
Step 6: Add the 9V Battery
Snap a 9V Battery to the battery clip. The Letter L should be displayed on the 7 Segment LED Display. Next soldered a red wire on the pcb where "Probe" is located. Last, soldered a black wire next to the black wire attached to the 9V Battery Clip. Now, the Logic Probe is ready to trouble or analyze digital or microcontroller circuits.