The low-cost, reliable, ubiquitous smoke detector is an example of complex physics and optics made real by semiconductors. This part looks at the two widely used approaches to smoke detection. Q: How do smoke detectors actually detect smoke? A: There are two basic and very different approaches, one based on photoelectric principles and the other […]
Smoke detectors and alarms, Part 1
The low-cost, reliable, ubiquitous smoke detector is an example of complex physics and optics made real by semiconductors. We’ve come to accept the basic residential smoke detector, which retails for just $15 to $30, as a standard home-safety accessory. Most building codes now require these in or near designated areas such as the kitchen, bedroom […]
PIGAs can indeed fly – and are still the best, Part 3: history and future
The PIGA is the oldest accelerometer widely used in rocketry and guidance, and still the best — but MEMS-based devices are getting closer. The previous parts looked at the principle and operation of the PIGA. This part looks briefly at its history and refinement and the MEMS-based versions of the PIGA being developed and used […]
PIGAs can indeed fly — and are still the best, Part 2: operation
The PIGA is the oldest accelerometer and widely used in rocketry and guidance, and still the best — but MEMS-based devices are getting closer. At the core of each single-axis PIGA is a gyroscope. The performance of this gyro — unrelated to the orientation gyros — plays a large role in determining the performance of […]
PIGAs can indeed fly — and are still the best, Part 1: frame of reference
The PIGA is the oldest accelerometer, is widely used in rocketry and guidance, and is still the best — but MEMS-based devices are getting closer. When you see an inexpensive drone, a more sophisticated one, an unmanned aircraft, a standard piloted aircraft, guided or intercontinental ballistic missile ICBM), an underwater drone or submarine, or a […]
What are the varieties of electromechanical on/off switches?
Despite wide use of “soft” on/off switching, the traditional electromechanical switch is still often required or preferred and is available in countless versions. Let’s look at some available switch styles. 1) The knife switch It doesn’t get simpler than the knife switch. The first and simplest switch is the knife switch (Figure 1). This style […]
What are the parameters of electromechanical of/off switches?
Despite wide use of “soft” on/off switching, the traditional electromechanical switch is still often required or preferred and is available in countless versions. As with all components, there are some top-tier parameters as well as many secondary ones, and some of those secondary ones may be very important in a specific application. As expected, the […]
What are the symbols for electromechanical on/off switches?
Despite wide use of “soft” on/off switching, the traditional electromechanical switch is still often required or preferred and is available in countless versions. Switches are represented by their schematic diagram symbols, which correspond to the number and arrangement of their contacts. Schematic symbols tell part of the story In an electromechanical hardwired on/off switch, the […]
What is the role of electromechanical on/off switches?
Despite wide use of “soft” on/off switching, the traditional electromechanical switch is still often required or preferred and is available in countless versions. Switches are an integral, very necessary part of most electronic products. They have two broad roles: As power switches which, as their name indicates, cut the flow of power from the source, […]
The automotive Tire Pressure Monitoring System, Part 4: Issues
Sensor-based monitoring systems for tire pressure can warn of potential problems, but there’s much more to the story than just a pressure-measurement system. The TPMS adds a highly specific safety-related feature to cars. However, as with many presumably good ideas, the “devil is in the details”, and that’s especially true for the TPMS. There are […]
