Nuts & Volts - April 2005

In The Trenches

sons for this: First, if these points are to be fixed in some manner, it is better to do this at the start of the project while it’s still on paper.

Second, honesty with the client cannot be overestimated. If the client thinks — or finds out later — that you are keeping secrets from him, he will not be happy. (How would you react if your doctor neglected to tell you that the medication you were taking for high blood pressure might cause all of your hair to fall out?)

There are always changes to the design at this point. The client forgot something, your approach gives him a new idea, or some initial information was incorrect. There’s always something.

However, if you did the first two steps properly, these changes will usually be relatively minor and easy to accommodate.

Sometimes there are significant

modifications requested. This is called a “Scope Change” and basically means that the scope, or overall approach, of the design must be reevaluated.

In this case, it’s back to Step 1. This Design Review becomes another Preliminary Design Review. Another paper design must be created and another Design Review is required.

It is important to note to the client any significant production, servicing, or testing considerations here.

For example, going from through-hole to surface mount technology (SMT) may require a substantial financial investment in hardware and training. As noted above, never surprise the customer.

For RFQs, this Design Review is completed by the client. The client examines the paperwork submitted by the engineer to determine if it is

suitable. If so, then a contract is awarded (or, for a contest, a prize is given). It is at this point that the engineer is able to contact the RFQ client for any additional details or questions.

Build a Prototype

This prototype (or two or three) is a fully functional product; however, it may not have exactly the same characteristics as the final version. For example, the final version may specify tiny SMT parts that require special machines to solder to the printed circuit board (PCB). This prototype may use through-hole or larger SMT parts that can be handled manually.

It used to be that prototype circuits were wire-wrapped, but this is rare nowadays. Nearly all modern prototypes use a PCB in order to validate performance characteristics.