A logic level sensor is a device that senses if the output of a component is 1 or 0 (positive or negative). You know those nice level sensors with the LCD screens that cost around $25 ? This one is laughably cheaper and and does the same thing (It is a little less professional-looking than the store-bought ones, but still does what it is made to do).This one is designed for 5-volt logic circuits. I apologize for the lack of photos, but my parents do not yet have a digital camera.
Step 1: Obtain Components
you will need:
3 colors of 22-guage stranded wire (preferably red, green, and black)
2 100 ohm resistors
1 standard red LED
1 standard green LED
1 roll of electrical or duct tape, or a glue gun and gluestick
1 soldering iron and solder
Step 2: Solder Parts Together
Cut the wires to your taste, about 3", and strip them 1/4" on each side. Green is 'IN', red is '+', and black is '-'. Solder the parts using the schematic and the wiring picture.
Step 3: Put the Sensor in a Nice Package
Glob a glob of hot glue on it or wrap it up in tape.
Step 4: Test It
Stick the red wire on the positive side of the power supply and the black one on the negative side. Both LEDs should be lit.When you touch the 'IN' wire to positive, the green light should come on. When you touch the 'IN' wire to negetive, the red light should come on.
Step 5: Expand It
This is how one could make an analyzer with an infinite number of leads!(of course, the current output of the power supply would have to be infinite too). The picture explains it all. Make a ton of them and make all their negative and positive common.