Introduction: Parallel Cable Breadboard Breakout
I'm experimenting with CNC machines so I came up with this simple and inexpensive way to make an adapter to plug a printer cable into a breadboard. It uses a socket pulled off of an old printer and a 40 pin IC socket. The IC socket is needed because these connectors, weather store bought or salvaged, don't have the right spacing to fit into a breadboard. This can also be useful if you want to fit one to a prototype board with 0.1" spacing.
This method could be used with a DB25 connector, a DB36, or any other angled PCB mount socket. My example uses a socket and cable with a 36 pin Centronics connector, as found on many old printers, because that's the kind of cable and socket I had from a printer I took apart. If you want DB25 like a standard computer parallel port, it's pretty easy to find an old motherboard with one of those sockets that can be used in exactly the same way.
1 DB25, Centronix 36pin or other PCB mount socket that you want to adapt to a breadboard.
1 40 pin IC socket, preferably the kind with flat tabs, though the machined pin kind may work
Zip ties (optional)
Needle nose pliers/tweezers
Solder sucker or desoldering iron (if your plug is currently attached to a board)
Step 1: Desolder and Crack the Socket
I wont go into too much detail on the desoldering, there are Instructables to cover that. But you don't have to worry about overheating the connector in this case, you're going to crack off the back of it anyway.
So, getting on to that, take a pair of pliers and crack up the plastic on the back of the connector. Since it comes to an angle behind the connector it breaks away pretty cleanly. If you want to be really neat about it you can file off the rough edges left where you broke off the plastic surrounding the pins.
Step 2: Plug the Pins Into the IC Socket
Now for the delicate work. First bend the pins open as seen in the picture so you can work on just one side at a time. Take the needle nose pliers and plug pins into the IC socket. I have it sitting in a breadboard just to hold it all in place. I found it helped to spread out the pins first starting from the middle until they were about right then plug in the first one with the pliers and work your way down the line. Grip them gently so they stay flat to the slot in the socket. If you squeeze them too hard and they'll twist so they're flat with the pliers and not aligned with the slot.
Step 3: Solder the Pins Into the Socket
Now solder the pins into the socket, this is just to keep it all together and improve the connection. Do it by holding the soldering iron against the pin just above the connector and touching the solder the the point where the pin meets the plug prongs just until it flows into the connection.
After all the pins are soldered gently bend down the plug and bring the other row of pins near the socket. Repeat step two for this side and then solder in the same manner.
Step 4: Plug It Into Your Breadboard
The diagram below shows how the pin connections work out using a 36 pin Centronics connector. Use a DB25 connector and the pin connections should come across identical to the output on the parallel port.
On one of my breadboards I locked an adapter like this one down by drilling holes through the breadboard in the grove in the middle where there aren't any holes. just off each end of the adapter using a 3/16 drill bit. Then I put a zip tie across the top of the IC socket but under the pins of the connector for the printer cable and through the holes in the breadboard. The last picture shows the one that zip tied to the board. It's given me a good solid connection for prototyping CNC drivers.