Atomic clocks have shrunk from room-sized assemblies down to PC-board mountable modules, admittedly with lower performance than their big siblings but still far better than crystal-based timing alternatives. Engineering is largely about tradeoffs and constraints, and atomic clocks are no exception to this situation. As these clocks are being designed into smaller packages through innovations, […]
The PC-board atomic clock, Part 1: Primary and secondary standards
Atomic clocks have shrunk from room-sized assemblies to PC-board mountable modules, admittedly with lower performance than their big siblings but still far better than crystal-based timing alternatives. Atomic clocks are based on the transitions of energy states of specific elements such as cesium, ytterbium, rubidium, and others under specific and tightly controlled conditions. They are […]
Electronic engines valves: an idea whose time has come…and gone?, Part 4: The camless outlook
The electronically controlled, cam-free internal combustion engine seemed like a good idea, but technical and market realities stifled its acceptance. The camless engine is more than just a dream. In addition to working prototypes Sturman, Camcom, and Freevalve, manufacturers such as International Truck and Engine Corp (part of Navistar) had planned to use it in […]
Electronic engines valves: an idea whose time has come … and gone?, Part 3: The electronic camless approach
The electronically controlled, cam-free internal combustion engine seemed like a good idea, but technical and market realities stifled its acceptance. The previous parts of this article discussed the operation of the standard, cam-driven internal combustion engine with a mechanically driven intake and exhaust valve pair for each cylinder. This section looks at the alternative of […]
Electronic engines valves: an idea whose time has come … and gone?, Part 2: Improving the conventional design
The electronically controlled, cam-free internal combustion engine seemed like a good idea, but technical and market realities stifled its acceptance. Part 1 provided the context for the classic cam-based ICE valve system and alluded to some limitations. This part looks at approaches that have been devised to overcome these issues to some extent. This pushrod-and-cam […]
Electronic engines valves: an idea whose time has come … and gone?, Part 1: Conventional engine design
The electronically controlled, cam-free internal combustion engine seemed like a good idea, but technical and market realities stifled its acceptance. Despite all the attention given to electric vehicles (EVs) as the inevitable replacement for vehicles powered by the venerable internal combustion engine (ICE), the reality is that for the foreseeable future, cars and trucks will […]
An overview of filters and their parameters, Part 4: Time and phase issues
Understanding how filters are characterized is the first step in choosing an appropriate topology with suitable specifications. Thus far, we have focused on filters primarily in terms of their frequency response. However, it is equally legitimate to look at their time-domain and phase-related performance, and in many cases, just as or even more important. Q: […]
An overview of filters and their parameters, Part 3: Key parameters
Understanding how filters are characterized is the first step in choosing an appropriate topology with suitable specifications. This part looks at the basics of filter characterization and parameters. Q: What is an example of a very basic filter? A: The most common analog filter is the single-stage low-pass RC filter (Figure 1). It is often […]
An overview of filters and their parameters, Part 2: Basic concepts
Understanding how filters are characterized is the first step in choosing an appropriate topology with suitable specifications. Filters are both a simple and also complicated and often confusing topic. This part clarifies some of the issues. Q: Why are so many discussions about filters so confusing? A: There are many reasons, but one is that […]
An overview of filters and their parameters, Part 1: Context
Understanding how filters are characterized is the first step in choosing an appropriate topology with suitable specifications. Mention “filters” to electrical engineers of the older persuasion, and you’ll likely see a look of nostalgia mixed with fear. Why so? Because “back in the day” a course on filter theory was mandatory for nearly all EE […]
