Logic Chip Tester

This is a logic chip tester for the 7400 series of logic chips, covering the AND, OR, NOT, NAND, NOR, XOR, BUFFER, JK ff, and D ff. This was a project started by Dr. Tim Frank of Glendale Community College. The actual program is a product of Dr. Frank and two other students (Stephen Bakle and Noel Rojas), with the Dr. Frank being the main programmer. Dr. Frank also designed the circuit board labeled "Socket Board" using Eagle CAD. With his permission both the code and the artwork for the board are being published and included in this Instructable. Before I transferred to ASU I was asked to help develop a case for the chip tester due to my experience in modeling software and the case has evolved several times. While at ASU I continued to work on the case for the project continued to improve and change shape with using Fusion 360. As a mechanical engineering student I must give the warning that I know very little on Logic, but I can defiantly assemble and design some circuits.

Parts:

•  3D printed parts:
•  X1, Case Top
• X1, Case Bottom
• X1, Battery compartment separator
• X1, Battery cover
• X2, Battery cover tabs
• Purchased Parts:
• X1, 16 pin ZIF socket
• X1, 5.5mm Barrel Plug DC female 3 pin (comes in sets with waterproof caps)
• X1, 9 Volt battery connector
• X1, 20A 12V DC Round Toggle LED switch (also sold as rocker switch and usually advertised as car and truck switches on Amazon)
• X1, Right Angle 16 position header (https://www.walmart.com/ip/10-Pack-of-0702471601-Connector-Header-70247-1601-Through-Hole-Right-Angle-16-position-0-100-2-54mm/526821668)
• X1, IDC Box Header 16pin Male Header
• X2, 16pin Female Header IDC (it may take several if cable is miss cut.)
• X1, Rainbow Color Flat Ribbon Cable 16 conductors (I would suggest having at least a 12-inches for mistakes happen.)
• X1, Kuman 3.5-inch TFT Touch Screen for Arduino
• X2, Jumper wires (molded ends and at least 5 ½ inches in length)
• X2, 5-inch sections of 26-gauge wire (two different colors for each wire will help with color coding)
• X1, ELEGOO MEGA (or comparable board from other brands or Arduino
• X3, M3 heat set nuts (P-6075-3BR038 used can be found on McMaster as 94180A331) 
• X1, M3 Countersunk 4mm
• X2, M3 Button Head 6mm
• Consumables
• Heat shrink (assorted sizes)
• Super Glue
• Solder
• Custom Order/made
• X1, Socket Board (files are with the Instructable (https://jlcpcb.com/) was used to make the board used)

Tools:

• Needed (don’t Forget Safety Glasses)
• Soldering Iron
• Flush Cutters
• Pliers
• Scissors
• Craft knife
• Precision Pick and Probe Set
• Wire Strippers
• Lighter
• Pin Vise (with assorted bits)
• 3D printer
• Highly Suggested but not necessary
• Heat set tip for soldering iron (to insert the M3 inserts)
• Wooden block with holes
• Solder Sucker
• Deburr tool
• Tapered Reamers
• Multimeter to check connections
• IDC crimper (this makes the ribbon cable a hundred percent easier to do)

The artwork for this board was created by Dr. Frank and can be downloaded at the following dropbox link

https://www.dropbox.com/sh/uws5gfcpbu3c9yx/AADUrSjRutXGlYbBdNFtDO_Ba?dl=0

The pads need to be on both sides for soldering and it was found to be easier to have it sent off to be made.

The board used in this Instructable was made by https://jlcpcb.com/

1. Download the Files which were created in Fusion 360 and place them into the slicer of choice (I use Slic3r and the files have somewhat been optimized for them. The top may have to be reposition and all of the prints should have the largest flat face on the build plate.
2. When slicing the files the usb port opening on the bottom case does not need supports if the slicer does not remove them for being too thin. A 0.4 mm nozzle was used to print the examples shown in this Instructable.
3. The two large pieces of the case can be printed at the same time on an 200mmx200mm printer as shown in the screenshot.
4. Two of the tabs will need to be printed also bringing the total 3D printed part count to 6 pieces.
5. I have included the top and bottom of the case as Fusion 360 Archive Files (f3d file type) incase anyone has fitment issues due to slicer or printer since they were designed with offsets from the printer I was using.

I strongly suggest putting on safety glasses on while doing this project especially with removing items or soldering.

Tools:

• Flush cutters
• pliers
• Reamers
• deburr tool
• craft knife
• Probe set

Supplies:

• Top case
• Bottom case
• Mega
• Barrel plug
• Toggle switch

The supports for the holes should remove with little effort, but the holes are undersized to allow for material removal to have a perfect fit with the barrel plug and the toggle switch. They should also be test fitted to ensure that the holes are not to small or too big.

The usb port hole supports can be removed with a craft knife and can be cleaned up with the deburr tool. The Mega should be test fitted to make sure that it fits, not that it is suggested to trim the leads that are shown in the attached pictures to ensure a better fit.

To remove the supports in the screw holes at the top of the bottom case with the least amount of trouble place it on the suggested wood block with holes lining up a hole with the location and taking a straight probe smacking it through the screw hole pushing the support material down into the hole in the block. This should push out a core that can be removed.

To remove the battery cover screw support one can, take a pliers and pull it off. 

The holes for the battery cover tabs will also need to be cleaned out

After cleaning up the prints there is some gluing that needs to be done. This way it has some time to dry while you can work on the other parts of the tester.

The tabs need to be glued to the cover for the battery. Put some super glue into the pockets and then place the tab into pocket. The tab should stick out enough that will poke into the holes on the bottom case in the battery compartment which is about the thickness of the wall of the case. An example was done in purple because I did not think the clear would show up well on camera, but the end result can be seen in clear.

The thin sheet gets glued to the top of the battery compartment to keep the battery in the compartment and to hide some of the wiring. A thin bead on the top edges and then the piece is placed on top.

These pieces can be set to the side for now.

Tools:

• Flush cutters
• Craft knife
• Pliers

Supplies:

• Kuman 3.5-inch TFT Touch Screen for Arduino

I strongly suggest putting on safety glasses on while doing this section flush cutters like to launch leads and pins across the room

Due to the design of the case and the Vin and GND pins have to be cut off the screen. This does not remove any functionality of the screen in the scope of this project. Wear Safety glasses

The two pins are pointed out in the images. It is easier to remove the pins when the spacer is removed. This can be done by cutting the spacer and pulling it off with the pliers. Once it is off, the flush cutters can remove them without damaging other pins.

Tools:

• Flush cutters
• Pliers
• Soldering iron
• Pin vise with assorted bits

Supplies:

• Mega

I strongly suggest putting on safety glasses on while doing this project especially while soldering and desoldering (especially the method used below).

To make the case as compact as possible the header on the Mega is modified.

To remove the original header one could desolder the whole thing with great care so the original piece stays intact, but time is an issue. The quick way is to remove the plastic part so all that is left is the pins soldered to the board. Once this is done flip the board so pins are easily accessible, then heat on individual pin. Once the solder is flowing lightly strike the board against your work surface this will dislodge some solder and the pins. This does fling solder onto the work surface and it will adhere to it so be mindful of what is at the receiving end of the solder. With all of the pins out there still may be some solder left blocking the holes. You can us a solder sucker to remove it but you can also add some solder and repeat the method above with some success.

If you haven't I would suggest clipping the leads for the usb and the power ports.

Grab the pin vise and find the bit that just is a bit to big to fit into the clean holes but with a couple of twist enlarge the hole so the Right Angle 16 position header can fit into pins 30-45 (the pins are just slightly to big for the Mega's holes).

Once the new header can fit into the correct pins (30-45) it should be placed with the opening facing to the usb and power ports as seen in the attached images. After it is determined that it is satisfactory it can be soldered into place.

Tools:

• Craft knife

Supplies:

• ZIF socket

On the ZIF socket there are 6 little protrusions that need to be removed. The quickest and easiest way to remove them is to slice them off with a craft knife, but one can file them down. This is critical for the assembly of the top of the case,

Tools:

• soldering iron
• heat set tip

Supplies:

• bottom case
• top case
• X3, m3 heat set nuts 

While a regular soldering iron tip can be used the tip made for the inserts makes it a lot easier to put them in straight and controlled. I set the iron to about 210 Celsius.

The easiest to insert is the battery cover insert on the bottom case and can be done while the glue is still drying. Place the insert on the tip of the soldering iron with the taper of the insert going inward. Be careful it is easy to burn oneself, and if one falls off do not pick it up right away for it will burn you (speaking from experience here). Place the insert into the hole and apply a downward force until the top of the insert is flush with the top of the pocket.

When doing the posts on the top case one has to take care to not move the post, if the post moves to much you may try to fix it, but you may end up having to reprint it. Since the posts have less material they will be a lot quicker than that of the pocket one.

Tools:

• soldering iron
• Flush cutters
• multimeter

Supplies:

• top case
• Custom board
• ZIF socket
• IDC Box Header 16pin Male Header 

The male header should be orientated as shown in the third figure. Then soldered into place. After it being soldered into place the pins need to be trimmed as flush as possible to allow the board to sit as close as possible. The board will just barely fit into the recess on the top cover and may need to be slide around until the holes for the ZIF socket can be seen and the socket can be placed through the hole of the cover and the pins go through the custom board. The pins will barely clear the board and pressure while soldering has to be applied so the pins can be soldered.

After finishing this step I would suggest testing the header to the ZIF socket with a multimeter just to be sure there is a connection.

Tools:

• soldering iron
• Flush cutters
• Wire strippers
• Lighter
• Craft knife

Supplies:

• bottom case
• X1, Barrel plug
• X1, Toggle switch
• X2, Jumper wires (molded ends and at least 5 ½ inches in length
•  X1, 9 Volt battery connector 
• X2, 5-inch sections of 26-gauge wire (two different colors for each wire will help with color coding
• Heat Shrink
• Solder

Take the jumpers and bend them so they can sit under the screen as seen in images 3 and 4.

Place the battery connector through one of the holes in the compartment and tie a not to provide strain relief. Run the wires through the barrel plug's nut and cut the heat shrink and place on. Take the ends of both the battery connector and the 26-gauge wire and strip off about a 1/2 inch. The power goes to the one that is bent on the barrel connector. Follow the images and once they are soldered put the heat shrink on and use the lighter (more focused heat that will not warp the print like a heat gun will). Run the jumpers out the switch hole and cut and strip them along with the other ends of the 26-gauge. Ground goes to the brass spade and the end spade goes to the VIN jumper while the middle one goes to the power source. Solder and heat shrink too. Finished product should look like the final image.

Tools:

• Scissors
• IDC crimper

Supplies:

• bottom case
• top case
•  Rainbow Color Flat Ribbon Cable 16 conductors 
• X2, 16pin Female Header IDC 

Orientate the connector as shown in the second image then crimp it. Check fitment and then measure how long it needs to be for it to reach the other connecter and then trim cable with scissors (don't use someone's good scissors for this). Then crimp on second connector and it should fit like the last image.

Tools:

• Craft knife
• Allen wrench

Supplies:

• bottom case
• top case
• X1, M3 Countersunk 4mm
• X2, M3 Button Head 6mm

Attach the cable to both connectors and then close the case. Place the two button head screws into the holes and tighten with wrench (make sure the inserts are aligned before placing the screws in.

Then place battery in and place battery cover into is position (note the hole may need to be cleaned with the craft knife). Be careful you may end up breaking a tab off like I did due to me not gluing it well. Tighten the screw with the Allen wrench and you are not ready for software if the device powers on with the switch (if no software is loaded it will be a blank screen).

Please note that the top of the case may want to lift up, this can be fixed by adding a bit of glue (I prefer hot glue that way if there is something wrong you are not fighting) or for a more permanent solution is to take some extra filament and a soldering iron smooth it over the joint to act like a weld. If you do the soldering iron method it does take some practice to make it look nice and have a flat knife like tip for your soldering iron does help, but please be aware that certain plastics may release toxic fumes when heated pass a certain temperature and proceed with caution to not burn yourself.

The attached code curtesy of Dr. Frank will need to be compiled for the tester to work, but the following libraries need to be installed too.

Adafruit GFX Library

Adafruit TFTLCD Library

Adafruit TouchScreen

MCUFRIEND_kbv

after these are installed the code can be compiled.

Once compiled your tester should function with the notch in the chip pointed and moved to the section of the socket closest to the lever. If the chip is good the screen will flash green and if bad will flash red. If there is a bad connection the screen will flash red in error and will do so for every test until the issue is fixed.

Have Fun.