On prototyping

So you made your plan for a very keen electric gizmo. And now you got to see if it works. If you are like me, your first design is already errorfree so you can start large scale production in a far east PCB mill. For all other people, it may be a good idea to first see if it runs at all. In general these are the steps in the design cycle:

  1. Recognize a problem
  2. Turn it into an opportunity
  3. Create an electronic solution
  4. REPEAT UNTIL errorfree
  5. Redraw your circuit
  6. Write a manual
  7. Create Gerber and Excellon files
  8. Determine how high you want to set your stakes
  9. Find a PCB house that can handle your order at a good price; remember though: pennywise or poundfoolish?
  10. Find a way to assemble the circuit boards
  11. Find a way to produce the case
  12. Find a way to wrap your gizmo
  13. Find a way to sell your product
  14. Pay your taxes
As you see, step 4 is rather big. It is your design cycle. It is not good if you are the only person in that cycle. You are the designer and the tester and the evaluator. In the ideal case these would be three different persons. In a one man operation, the single man must be strong enough to come up with the idea, describe it in a manual and a product circuit. Then come up with test criteria and find the time to objectively evaluate your prototypes.

Electronic prototyping techniques

Prototyping electronic circuits is a wide area. There mare several techniques and methods and most of them are rather expensive. Which is nog a good thing if you are still developing. I have experience with the following prototyping techniques:

Name Description Cost Speed
2D Wiring In '2D Wiring' I use perforated board (VERO board) with one solder pad per hole. What I do in fact, is simulate the traces on a printed circuit board with (scraps of) solid wire which are soldered in place. This way you can lay up to four layers of wires if you work carefully. But I would not recommend laying more than two layers. Low Low
Wirewrap Wirewrap is a very fast and dense prototyping method. You also start with a VERO board and populate it with your components. You can use ANY placement of the components. IC's need to be placed in special wire wrap sockets with long, square, pins. Then you start connecting the pins with wirewrap wire and a wrap tool. Just run the wires from point A to point B. Connections are made by wrapping the wire to square pins or soldering to round pins. Moderate High
Breadboard On a breadboard you can make small circuits with not too many components. You quickly run out of space on a breadboard due to the many (unused) connection points. A breadboard requires only components and 'hookup wire' so it is not very expensive and the board itself can be re-used many times. Moderate Moderate
RoadRunner Roadrunner is a method that looks similar to wirewrap with the differences that no special sockets are required and all connections are soldered. You need to use special roadrunner wires (copper core with an insulation that melts in a drop of tin, thereby acting as extra flux agent). The wire is quite expensive yet all other components are not. On a densely populated board it can be difficult to solder the next wire. Low High
PCB-maker This is the ideal situation. You can now see if it fits on the board and how components interact. The final prototype should always be one on a PCB. No compromises. Yet higher costs since PCB makers will charge the same tooling costs as for a batch of 4000 boards. Plus small order costs and such. High Low

The topics

Below are the topics covered in this section. The topics are mentioned in chronological order: newest edition is further down the page. I think that makes easier reading.

2D Wiring

In 2D Wiring you use the cut off parts of component leads to create your own PCB tracks on Vero board. If you are short on cut off leads, you can use solid hookup wire, as used in Breadboarding.

The method in some keywords:

Read more about it in the dedicated file.

Wirewrap

With wire wrap you just sit on the kitchentable while your spouse is preparing the food. You whip out your tools and wire and sockets and start rotuing wires from point to point. No heat required. No chemicals involved. Just a slight myopia and the desire to get things done.

The method in keywords:

Read more about it in the dedicated file.

Breadboard

This is not my favorite method. Too clumsy and too chaotic. Topic coming up anyway.

Roadrunner

Coming up

PCB maker

For this I already covered a lot of ground: in the PADS (or PCB) section. There are examples for Eagle and PADS.

Page created 12 November 2008,

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