Pocket 256 Bit Logic Analyzer

This is a pocket size 256 Bit eight input digital analyzer for checking digital circuit functions that I built for my own use at home. It cost less than twenty dollars to build and it enables me to test switching circuit functions at slow clock speeds as well as I can check 256 bit counter outputs. This analyzer works well and is cheap to build.

Step 1: 555 Timer

If the clock on your circuit is too fast you won’t be able to see the functions. To aid with testing on prototypes I built this variable speed 555 timer clock so I could adjust the speed of the flashing LEDs while checking circuit functions.
Parts

1. 1 555 timer
2. 1 LED
3. 1 2N3904 transistor
4. 1 switch
5. 1 50 k& pot
6. 2 1 k& ¼ watt resistors
7. 1 150 & resistor
8. 1 33 uF 6 Volt capacitor
9. 1 47 uF 6 Volt capacitor
10. 1 proto board
11. 1 8 pin IC socket
12. 1 pot knob
13. 4 feet or mounting posts
14. Wire

Step 2: Operating the Analyzer

This analyzer works very simply, when hooked up to 5 volts power the green LEDs light up indicating high or the binary 1.

When the inputs are connected to a circuit or ground the green LEDs turn off and the red LEDs light up indicating low or the binary 0.

As the circuit the analyzer is conected to runs the LEDs switch from red to green indicating 0 or 1 on the input as shown on input #1 here in image #3.

Step 3: The Analyzer Circuit

Each input is very simple on its own consisting of:

1. 1 red LED
2. 1 green LED
3. 2 150 & ¼ watt
4. 2 18 k& ¼ watt
5. 2 2N3906 transistors
6. 1 inverter

However 8 inputs multiply the circuit 8 times that is:

1. 8 red LED
2. 8 green LED
3. 16 150 & ¼ watt
4. 16 18 k& ¼ watt
5. 16 2N3906 transistors
6. 2 DM74LS04 hex inverters
7. 2 14 pin IC sockets
8. 1 proto board
9. 4 feet or mounting posts
10. 1 10 pin connector I used a 14 pin IC socket
11. Wire

I looks more complcated then it is.

Step 4: The Analyzer in Operation

Once you build the analyzer you can start testing circuits.

Since I did not ground the last three inputs this circuit should put out a digital output on the green LEDs of:

00100111
10101111
01000111
11010111

and back to 00100111

Watch the green lights in the video