A few months ago, we conducted an email interview with the Keysight Digital Multimeter team. Many iconic products have emerged from this team, including the 3458A, 34401A, and 34970A. Given the immense success of the 34401A, we couldn't help but ask Wayne H. Willis, the product manager for the multimeter team, why this particular model was so successful and what the team could do next after achieving such monumental success.
Wayne joined Hewlett-Packard in 1979 and was the first to manage the production line. In 1992, he wrote an article in the HP Journal about using the VXI platform in automated test lines. Known for his enthusiasm for computers, Wayne has always been at the forefront of innovation.
The interview was incredibly insightful. To complement the discussion, we even took apart one of their new 34461A digital multimeters. The teardown details will be shared in the second half of the article.
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EEN: Hello Wayne, could you tell us about your role in the Keysight multimeter team and introduce us to the team?
WW: Hi everyone, I'm Wayne Willis, the R&D Manager for the 34461A and an Electronic Engineer. I've been with HP since 1979 (that's 38 years!). My daily responsibilities involve working closely with R&D and product marketing engineers to design and develop new products. Since our conversation is centered around digital multimeters, here’s a photo of our R&D team. Our team consists of both young and experienced engineers, some of whom were involved in the 34401A project. You can easily spot them—they’ve got less hair!
[Image of the team]
EEN: Did you celebrate when the 34401A was officially discontinued?
WW: Absolutely! We celebrated in a big way. On December 1, 2016, we held a grand retirement ceremony for the 34401A. We invited as many former team members as possible, including those who have retired. It turned into a wonderful reunion of old friends. The host, who was responsible for the market launch of the 34401A, shared many amusing stories, bringing back fond memories.
EEN: From your perspective, what made the 34401A so successful?
WW: The 34401A was truly revolutionary. At $5,500, it offered 6.5-digit accuracy and resolution, and its durability and reliability remain unmatched. Its success lies in balancing affordability, performance, and ruggedness—exactly what users needed.
EEN: What made the 34401A so enduring? If you were to design a similarly successful product today, what would be the biggest challenge?
WW: One key factor was the extensive market research conducted before development. Using the House of Quality (HOQ) framework, we prioritized customer feedback. This method was innovative at the time and proved highly effective. For instance, we added a rubber bumper, which wasn’t present in previous HP products. This design choice met customers' psychological expectations and influenced competitors as well.
Designing a successful product is challenging because it requires balancing cost, performance, and reliability. It demands meticulous attention to detail, innovation, and teamwork among R&D, operations, and suppliers. I’m proud of what we achieved.
EEN: Any regrets from being part of the 34401A project?
WW: Not at all. It was perfect. [Smiling face...]
EEN: The Multi-slope ADC has evolved to its fourth generation on the 34461A. What improvements have been made to this latest iteration?
WW: We continue to refine our A/D conversion techniques. The original multi-slope integration evolved into the second generation (like the 3458A and 34401A) and the third generation (34410/11A). The fourth generation uses a delta-sigma algorithm, improving both resolution and linearity. While high-level chip integration is ongoing, a single-chip solution might not meet all our accuracy requirements. Thus, our current design still relies on multiple chips and devices. Technology will evolve further, and perhaps soon, a single-chip solution will meet all our needs.
EEN: Many companies are now focusing more on applications and solutions. How can traditional instruments like multimeters adapt to this trend?
WW: Indeed, the market demands more specialized applications. For multimeters, we respond by upgrading firmware, offering customizable apps, and developing software to meet unique requirements. This approach mirrors how smartphones handle apps.
EEN: What technological innovations distinguish the 3446X series from past products?
WW: The new multimeters feature an improved ADC design, allowing us to achieve 7.5-digit accuracy and resolution at a lower cost and smaller footprint. This design also supports faster reading speeds. Additionally, we’ve introduced Auto Calibration (ACAL) in the 34465A and 34470A to maintain accuracy under varying conditions.
EEN: The user interface of the 3446X series has changed significantly. What are your thoughts on this? How does the new UI benefit users?
WW: Users love the new interface. It’s intuitive and easy to navigate. The larger color screen allows us to display not just readings but also statistical results graphically. This enhances insights into measurement data. Users can now visualize trends, histograms, and statistics, making data analysis more comprehensive.
EEN: Will future desktop instruments incorporate consumer electronics technologies like touchscreens or wireless connectivity?
WW: We’re always exploring new technologies. If they’re reliable, affordable, safe, and beneficial to our customers, we’ll consider integrating them. For instance, we recently implemented the MTP protocol on the USB interface, allowing users to drag and drop data files directly from the instrument to a PC.
EEN: Reliability was crucial to the 34401A’s success. How have you ensured reliability in the new multimeters?
WW: Our products undergo rigorous testing, including temperature/humidity limits, temperature cycling, mechanical abuse, input signal abuse, ESD, and transient testing. For example, while we recommend operating temperatures between 0–55°C, our tests go far beyond these limits. We also account for potential operator errors, ensuring the device remains undamaged under extreme conditions.
EEN: Finally, can you give us a hint about your next product? Could it be the legendary 34480A or a new 34970A?
WW: Stay tuned! I think you’ll love it.
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After the interview, we decided to disassemble the 34461A to get a closer look. The design is remarkably efficient, using only six screws in total, three of which secure the fan and GPIB interface. The circuitry connects to the housing via clips, making it easy to disassemble but challenging if not properly removed.
The 34461A retains the same design philosophy as the 34401A, with a simpler hardware layout. Removing the mainboard from the front panel required some effort, but once the T-shaped black buckle was removed, it came off easily. Interestingly, the 34461A uses a connector inside the yellow circle, eliminating the need for an additional gray data line used in the 34401A.
After the teardown, we discovered the multi-slope integration circuit under the metal shield. Removing the shield revealed the LM399 reference level, a key difference between the 34461A and other high-precision models. Despite its sensitivity, the 34461A’s performance remains robust.
Reinstalling the multimeter was satisfying, and the self-test confirmed everything worked as expected. The graphical UI is excellent, blending new technologies with respect for tradition. Even seasoned engineers can quickly adapt, requiring minimal reference to the manual.
This UI has been so well-received that domestic manufacturers have adopted similar designs.
[Image of the UI]
[Image of a domestic manufacturer copying the UI]
This was a rewarding experience, and we hope you enjoyed this deep dive into the 34461A. Stay tuned for more exciting developments from Keysight!
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