Beyond the Basics: A history lesson
I have to admit it. Fluke owes much of its success as a handheld digital multimeter (dmm) manufacturer to a persistent customer who wouldn’t take “No” for an answer.
I attended the meeting with this “in your face” customer, who traveled from the Midwest to our headquarters near Seattle to make his case. I, as a product planner, learned much about the importance of listening carefully to customers’ comments as we planned and designed new products in the years that followed.
The first Fluke handheld DMM
As I’m sure many of you are aware, Fluke got into the handheld digital multimeter business with the introduction of the model 8020A in 1977.
From the article “The Little Gray Box That Started a Revolution,” published in about 2002:
“Before the 8020A was retired in 1984, more than 250,000 were sold. And the 8020B, with five additional models based on the same technology, brought the total to 1 million units by the end of the decade. Combine that with over 2 million 70 Series meters (a new design introduced in 1983), and Fluke was in the handheld test tool business big time.”
The story I’m about to tell you took place in about 1980, as the company was riding high on the success of our first family of dmms. What our customer told us that day was a major factor in the change of design direction that led to the 70 Series, and nearly all subsequent Fluke handheld dmms.
Figure 1. The switch deck of the Fluke 8024A.
The “new design introduced in 1983”
This story is about that “new design introduced in 1983” - using a rotary switch instead of push buttons.
The customer who came to visit us was the manager of the service organization for a major manufacturer of equipment that used both electrical and electronic components. His company was one of the major purchasers of our handheld meters.
He told us that our side-mounted push buttons led to technicians making several mistakes as they serviced the company’s equipment. He went on to say that, while he appreciated the reliability and accuracy of our meters, he would be forced to switch to competitors who used rotary switches if we failed to meet his demands. He said that his technicians made far fewer setup mistakes with a rotary format.
Why were we hesitant to design meters with rotary switches? The answer was reliability. We had considered the possibilities during our design of the 8020A, but found all the commercially available rotary switches we tested to be lacking in this very important attribute. That was because the 8020 family was manual ranging, resulting in many contacts being required to select all the function and ranging combinations while maintaining the necessary spacing to safely handle high voltages. Each of the push button switches had many poles (see Figure 1).
Figure 2. 8024A, with side-mounted push buttons, in kOhms.
To understand where the customer was coming from, consider the following while referring to Figure 2:
You have to determine all this from the positions of the buttons, and read the resulting selection from the correct column of range information. That’s because the limited capability of the LCD display did not allow for any annunciators to confirm the settings.
Necessity is the mother of invention
This customer’s visit launched us on a program to design the integrated rotary switch system that has been used in nearly all Fluke handhelds since the introduction of the 70 Series (see Figure 3).
Figure 3. Representative 70 series rotary switch; relatively simple compared to Figure 1. Photo courtesy of Mark P. Roberts.
Why did rotary switches suddenly become acceptable?
Well, for one thing, we were able to implement autoranging in the digital logic in later chip designs. That alone greatly simplified the switching.
Then, there was the matter of the status display (see Figure 4, the Fluke 75 multimeter). LCDs had come a long way by the early 80s, and we were able to clearly show measurement function information along with the readings and a bar graph on the display.
A lesson well learned
Figure 4. Fluke 75. Photo courtesy of StevenJohnson.com.
Today, Fluke industrial design engineers spend many hours doing usability testing, using drawings and mockups. They ask representative customer volunteers to comment on control layouts and display labels and then work with the hardware and software designers to make the user interfaces of new products as clear and simple to operate as possible.
All it took for me to get the message was an outspoken customer in the 1980s.