Wrapping. Homemade breadboard
In the last article, we examined the technology of wraparound editing. But practice is the criterion of truth. In addition, DIHALT asked a specific question about how to deal with the details. It is clear that the details are put on the board on the one hand, and all connections occur on the other hand (it seems to be logical, but how?). There are ready-made boards for wrap-ups , but they are very expensive.
In this article, I will show my decision how to mock up a wrap on a circuit board, which I made myself in just a couple of hours.
First hard steps
At the end of the first part I talked about the practical application and the problems that I encountered. Now I am developing a synthesizer project on FPGAs and am in the process of constant experiments, therefore the circuitry is constantly changing. Re-commutation is constantly required. If inside the FPGA it is enough to transfer the signals to other outputs, then everything does not happen so fast on the board. It was in order to increase the rate of change of the circuit, its reliability and resistance to repeated alterations, I took up the installation of the wrap. But not everything is so smooth.
My project consists of two boards: the board on which the FPGA chip is located and the expansion board for it is a synthesizer. Boards are connected via a 40-pin connector using a cable. Further, I did the entire circuit on the expansion board by surface mounting. That is, the wires were soldered directly to the connector pins. And in order to switch to wrap-around mounting, I need to bring these 40 lines to the side of the board where the pins will be. There, for example, I deduce, for example, 8 resistors of 10 kOhm. I do as I decided earlier. I insert the racks into the board. I solder the radio elements from above to the racks. In the case of the connector, I had to solder the wires. Everything turned out very badly: for a long time, not reliably, not conveniently, not beautifully. In addition, the racks were very badly flooded and it was very difficult to solder to them.
Top pins to go to Wire Wrap. Plug under them. And 20 bagels are wire. Below 8 resistors soldered to the racks
The same thing is on the other hand: the top row is the rack of the connector, below are the two rows of rack to which the resistors are soldered
After spending 3 hours and doing only half the work on the connector, and somewhat soldering 8 resistors, with sad thoughts I went to sleep.
There were two thoughts:
1) I did not correctly install the elements
2) I need to solve something with the fact that the racks are badly crowded
And before going to bed, insight came upon me!
Ready-made Wire Wrap boards are usually made by this principle.
On the one hand, elements
A are installed . On the other hand, it all comes out with pins.
Long pins. And besides the pins on the other side there is nothing at all.
And why am I not doing this? Why am I threading the racks, I can’t fix them in any way, and solder the radio elements to the racks?
This is nonsense! Radio elements must be soldered just to the breadboard as usual, and the pins should be led to the other side, where there are no copper conductors!
It remains only to solve the problem of tinning. The issue was resolved using flux F38N. I don’t understand how I used to live without him!
We do it!
We take the curved Chinese boards:
Soldering iron (I have a car 12 volt with the charger from there), the third hand, my favorite solder is POS-61 1.5mm two meters, and the opening of this fall is F38N, there’s still a thin tube into which I I collected acid and applied it to the racks.
We cut off the excess from the board, skins, degreases. We rape the racks. We install on the board and solder. Thanks to the flux and POS-61 in the coil, it was a pleasure to solder! Fast and beautiful.
From the end of the board, I make two strips of 20 from the racks. This is a connector for connecting to the FPGA card. There are two wires - power.
The rest of the mounting on the board is solely for prototyping the circuitry I need.
On the printed circuit side, we will solder discrete elements: microcircuits, resistors, capacitors, and connect them to one of the racks in the same place. Better yet, solder the panels and quickly insert all the elements into them.
And on the other hand, already connect the elements with a wire (the two lines on the right are the power).
When switching to wrap-up editing, you need to switch your thinking a little and start doing wrap-up editing. Move away from surface mounting and possibly solder. I couldn’t do it the first time. And now, when I made a new board, I almost began to make the same mistakes again. Here's an example: you need to transfer all 40 lines from the input-connector to the first line of racks. What am I going to do? Of course! Solder the wire from the connector to the first line. But this is a mistake. This is not necessary. In general, you do not need to transfer all 40 lines. Only those that are required in this scheme are needed (1) . And instead of soldering, we can apply a wrap-around installation. The racks are large, after installing the cable under it there is enough space to wind the wire (2).
(A few days later).
So now the board looks. During these days, it has changed several times, but all changes were made easily and quickly.
View from the mounting side of the wrap:
View from the mounting side of the elements (sorry, so variegated):
Conclusion. This method of prototyping suits me and I will use it in the future. Give it a try!