Product designers have to balance incompatible goals to achieve an optimal product for the consumer. Yet there are times that the outcome seems so senseless that you wonder what they were thinking.

Recently, my clock radio kicked the bucket after 20 wonderful years. This General Electric wonder had 2 alarms that could wake my wife or me with the sound of our favorite radio stations or to a buzzer. The display could be adjusted from near dark to penetrating light; and we could each wake to a different radio station. This early programmable model had lots of other features that made it the almost perfect appliance.

Finding a replacement has proven frustrating, despite the dozens of models that we've examined.

Of course there are new features that we didn't consider 20 years ago. Various models can wake you to your favorite track on built-in CD players (sometimes even CDs that you have recorded yourself). Some have inputs for MP3 players, so you can fall asleep to or wake to the songs you've downloaded from the Internet.

But we still can't find a design nearly as perfect as the one we had. We found plenty of dual alarms; but only one that lets us wake to different radio stations. Only a few are easy to program; none as easy as our original. In our ancient model, GE included shortcut keys to almost every function, as well as buttons that let you key in the digits -- whether you want to set the clock or the alarm, or hear a station that is not in memory. Newer models have shortcuts, but if you're trying to do something that is not programmed, such as go to a new station, the controls are time-consuming.

We actually found one Sony model that does make it easy, but the transformer block on the power cord is bigger than Rhode Island. So it's not good for older homes with limited electrical outlets. In essence, even the best designs have one or more design elements that seriously detract from the usability of the products.

I see this problem all over the place. A few years ago I bought a PDA (personal digital assistant) on which the designers changed the angle of the connector into which you would plug an optional external keyboard. This simple change meant users of older models had to buy new keyboards. Similarly, I've seen models in which they change the case design slightly so otherwise compatible connectors can't connect because they can't reach the connector. Frankly, I think these changes are done on purpose to get you to part with an extra $30 to $70.

Some companies have gotten very good at pushing their costs to the consumer. They routinely make the buyer purchase extra accessories, such as power supplies, battery chargers and other items that used to be included with the base product.

It's a breath of fresh air when a company lets you use a standard accessory. I've been noticing, for instance, that Motorola has been putting standard USB adapters on its phones. So you can use the same power supply/charger with multiple models. But the batteries are often different sizes.

Plantronics seems to have mastered the art of compatible accessories, although it uses its own proprietary design. The company's headset models use the same type of adapters compatible with interchangeable AC power cords, car power adapters and battery packs. One Plantronics power supply even has two connectors.

Consumers don't want to buy incompatible accessories. Product designers should recognize that.