So what is breadboarding? Basically it is a technique dating back to the early days of ham radio where circuits were built on a wooden board. Hams being what they are (always looking for some easy solution) pressed the family bread board into service as a base for the latest radio project. We should not also forget in those early days the kitchen was the hub of activity and many a kitchen table served as a workbench.

The fact that circuits were built "al fresco" may have been convenience but it served another valuable purpose --everything was out in the open and on a single level. Thus circuit measurements were easily made. Tracing of circuits was a snap as everything was right out in front of you. Recently I was repairing a Drake T4XB and I can't tell you how many times I had to flip the radio right side up and upside down. On a breadboard you can easily "see" everything all at once. Shown below is a breadboard I used when I was constructing a tri-band QRP SSB transceiver. As you can see there are lots of individual circuit boards and many components and adjustments. The initial circuit evaluations and performance would be difficult to assess were this built into a final assembly

 

There is no magic about this process but a couple of things must be observed and these are just common sense. For the individual circuit boards I drill holes in each corner as an early step. Using wood screws, each board is simply screwed into the wooden board. For circuit boards that are built on single sided coppeer vector board and are mounted on aluminum standoff pillars, I drill holes completely through the breadboard to accommodate a 3/4 inch 4-40 or 6-32 screw depending on the pillar used. The elevated board is then fastened to the breadboard by screws that pass thorugh the breadboard. The wood is soft enough so that a few extra turns will press the screw into the wood in a countersinking fashion. Thus the beradboard will be "flat" on the bottom side. Screws at opposite corners are all that is need to hold the boards in place --unless ths will be a permanent arrangement where having screws in each corner will make it looked finished.

In my typical building process I start at the back end and build forward. Thus while you see a completed breadboard I built and tested all of the circuits individually. As an example I started with the audio amplifier stage and got that working. Next I built a BFO followed by the detector stage and got that working and then mated those with the audio stage --now I had three pieces of the puzzle. Thus there is an ordered approach to building the circuit blocks and the sequencing enables the radio itself to be a part of the test system. This also enables finding a problem with a specific circuit before proceeding on to the next build. Thus when the last circuit board is built you have confidence that all those that were built previoulsy were all working as a stand alone.

You will note from the photo above that in the center is a series of terminal strips so that power leads can be provided to the various circuits. While the individual boards appear to be in a random array, they are not. In fact they are arranged much like a block diagram and more or less follow the signal paths. One critical concern is circuit interaction. So a little space between circuit boards is very much the order of the day and it may require some shielding to be installed on individual circuit boards. In case you are wondering the breadboard above is 2 Ft X 2 Ft and there was a spill over. Start small and you will get the hang of it and see the value as you are developing a project.