High-power LEDs (HP-LEDs) or high-output LEDs (HO-LEDs) can be driven at currents from hundreds of mA to more than an ampere, compared with the tens of mA for other LEDs. Some can emit over a thousand lumens. LED power densities up to 300 W/cm 2 have been achieved. Since overheating is destructive, the HP-LEDs must be mounted on a heat sink to allow for heat dissipation. If the heat from an HP-LED is not removed, the device fails in seconds. One HP-LED can often replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp.
(c) Class 3—Advanced High-Power Rocket means an amateur rocket other than a model rocket or high-power rocket.”
For most audio applications more power is needed at low frequencies. This requires a high-power amplifier for low frequencies (e.g., 200 watts for 20–200 Hz band), lower power amplifier for the midrange (e.g., 50 watts for 200 to 1000 Hz), and even less the high end (e.g. 5 watts for 1000–20000 Hz). Proper design of a bi/tri amplifier system requires a study of driver (speaker) frequency response and sensitivities to determine optimal crossover frequencies and power amplifier powers.
High-power rocket designs can vary widely as do anticipated altitudes and performance, but altitudes of 10000 ft and velocities in the supersonic ranges are not uncommon. A combination of (often) larger mass and higher apogees may require sophisticated recovery systems. High-power rockets are frequently flown with sophisticated electronic devices used for recording flight data (altitude, velocity, acceleration/deceleration, G-forces) and for deploying recovery methods or devices.
Since hybrid circuits are bi-directional, they can be used to coherently combine power as well as splitting it. In figure 21, an example is shown of a signal split up to feed multiple low power amplifiers, then recombined to feed a single antenna with high power. The phases of the inputs to each power combiner are arranged such that the two inputs are 90° out of phase with each other. Since the coupled port of a hybrid combiner is 90° out of phase with the transmitted port, this causes the powers to add at the output of the combiner and to cancel at the isolated port: a representative example from figure 21 is shown in figure 22. Note that there is an additional fixed 90° phase shift to both ports at each combiner/divider which is not shown in the diagrams for simplicity. Applying in-phase power to both input ports would not get the desired result: the quadrature sum of the two inputs would appear at both output ports – that is half the total power out of each. This approach allows the use of numerous less expensive and lower-power amplifiers in the circuitry instead of a single high-power TWT. Yet another approach is to have each solid state amplifier (SSA) feed an antenna and let the power be combined in space or be used to feed a lens attached to an antenna.
High-power model rockets can carry large payloads, including cameras and instrumentation such as GPS units.
High-power rockets are defined as rockets flown using commercially available motors ranging from H to O class. In the U.S., the NFPA1122 standard dictates guidelines for model rocketry, while NFPA1127 is specific to high-power rockets. In most U.S. states NFPA1122 has been adopted as part of the legal code. A smaller number of states use NFPA1127.
In most other countries, where HPR is supported, the regulations are similar to or derived from the Tripoli Rocket Association Safety Code and the NAR High-power Certification system.
High-power rockets are constructed from materials such as phenolic resin, fiberglass, carbon fiber, and other composite materials and plastics. Motor casings are normally machined aluminium with ablative phenolic or paper liners and are reloadable, i.e. can be used multiple times.
A high-power field (HPF), when used in relation to microscopy, references the area visible under the maximum magnification power of the objective being used. Often, this represents a 400-fold magnification when referenced in scientific papers.
Examples of devices that support high-power charging according to the USB Power Delivery specification include: MacBook, Chromebook Pixel, Surface Book 2, Dell Venue 10 Pro, Lenovo ThinkPad X1, Samsung Galaxy TabPro S, Samsung Galaxy Tab S4, iPad Pro, Nintendo Switch, Nexus 5X/6P, Google Pixel/2/3/4, ROG Phone, BlackBerry Key2, Essential Phone, HTC 10/U Ultra, LG G5/G6, Moto Z, Nokia 8, Razer Phone, Samsung Galaxy S8/S9, Samsung Galaxy Note 8/Note 9,Sony Xperia XZ1/XZ2, Apple iPhone 8/X etc.
As with low-power model rockets, high-power rockets are also constructed from lightweight materials. Unlike model rockets, high-power rockets often require stronger materials such as fiberglass, composite materials, and aluminum to withstand the higher stresses during flights that often exceed speeds of Mach 1 (340 m/s) and over 3,000 m altitude. Because of the potential risk to other aircraft, coordination with proper authorities is often required.
High-power rockets are propelled by larger motors ranging from class H to class O, and/or weigh more than 3.3 lbs or 1,500 grams at liftoff. Their motors are almost always reloadable rather than single-use, in order to reduce cost. Recovery and/or multi-stage ignition may be initiated by small on-board computers, which use an altimeter or accelerometer for detecting when to ignite engines or deploy parachutes.
High-power vertical-cavity surface-emitting lasers can also be fabricated, either by increasing the emitting aperture size of a single device or by combining several elements into large two-dimensional (2D) arrays. There have been relatively few reported studies on high-power VCSELs. Large-aperture single devices operating around 100 mW were first reported in 1993. Improvements in the epitaxial growth, processing, device design, and packaging led to individual large-aperture VCSELs emitting several hundreds of milliwatts by 1998. More than 2 W continuous-wave (CW) operation at -10 degrees Celsius heat-sink temperature was also reported in 1998 from a VCSEL array consisting of 1,000 elements, corresponding to a power density of 30 W/cm 2. In 2001, more than 1 W CW power and 10 W pulsed power at room temperature were reported from a 19-element array. The VCSEL array chip was mounted on a diamond heat spreader, taking advantage of diamond’s very high thermal conductivity. A record 3 W CW output power was reported in 2005 from large diameter single devices emitting around 980 nm.
In model rocketry, a parachute, streamer or other recovery device or method deploys at apogee, but high-power rockets may employ more complex recovery systems since altitudes can be much higher than their counterparts. In a high-power rocket, an altimeter or electronic timer may deploy a drogue parachute (which stabilizes the rocket in descent) or a controlled freefall (where the fore and aft sections are merely separated by a tether or umbilical cord, often made of tubular nylon). These recovery events can be brought about by small explosive charges (black powder or Pyrodex) or pressurized gasses (e.g., CO 2 ). At an altitude predetermined by the hobbyist, an altimeter deploys a main parachute that slows the rocket to a safe recovery speed. The most common varieties of altimeter use accelerometers, barometric sensors or a combination of both.
High-power rockets are predominantly powered by commercially available APCP-based motors or nitrous oxide-based hybrid motors.
High-power rocketry is a hobby similar to model rocketry. The major difference is that higher impulse range motors are used. The National Fire Protection Association (NFPA) definition of a high-power rocket is one that has a total weight of more than 1500 g and contains a motor or motors containing more than 125 g of propellant and/or rated at more than 160 Newton-seconds (40.47 lbf·s) of total impulse, or that uses a motor with an average thrust of 80 N or more.
In 2007, more than 200 W of CW output power was reported from a large (5 × 5mm) 2D VCSEL array emitting around the 976 nm wavelength, representing a substantial breakthrough in the field of high-power VCSELs. The high power level achieved was mostly due to improvements in wall-plug efficiency and packaging. In 2009, >100 W power levels were reported for VCSEL arrays emitting around 808 nm.
The high breakdown voltage of wide bandgap semiconductors is a useful property in high-power applications that require large electric fields.
As vehicle couplers for DC charging according to IEC 62196-3:2014 Ed.1 allow DC charging only with currents up to 200 A, they do not sufficiently cover the needs of the future charging infrastructure. Consequently the next edition of the standard will support currents of up to 400 A. Such high currents, however, result in several problems: they either require large cable cross-sections, leading to heavy and stiff cables, or require cooling if thinner cables are desired. In addition, the contact resistance leads to more heat dissipation. To cope with these technical issues, the IEC TS 62196-3-1 is currently under development; the standard will describe the requirements for high-power DC couplers including thermal sensing, cooling and silver-plating of contacts.