glossary:glossary_h
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glossary:glossary_h [2014/11/11 13:29] – external edit 127.0.0.1 | glossary:glossary_h [2020/05/08 00:18] – Clarify definitions and fix typos. Add Hysteresis term focused on electronics application. H0 is not HO. tgerbic | ||
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- | ===== Hall effect ===== | + | ===== Hall effect |
- | This a transistor | + | A Hall effect sensor is a semiconductor device often looking like a small transistor. When the device encounters |
+ | \\ See MERG TBs A7/2/ 3/ 4 (MERG members only) | ||
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- | Is a means of control | + | A handset is usually |
+ | \\ {{: | ||
+ | ===== Handshaking ===== | ||
+ | |||
+ | Handshaking is a process that allows two or more devices to establish communications, | ||
+ | |||
+ | |||
+ | ===== Happening ===== | ||
+ | |||
+ | A term devised and introduced in the documentation for the MERG Universal CANMIO, for an event that is internal to the module to distinguish it from an external event (on the bus). | ||
+ | For instance, say input 1 changes from high to low. In early modules of the CBUS range this would simply produce an ON event with EN (Event Number) of 1. In the Universal code for the CANMIO it produces a ' | ||
+ | |||
+ | ===== HASL ===== | ||
+ | HASL, or Hot Air Solder Leveling, is a process of coating the bare copper of an etched PCB with something like solder or varnish (solder mask). This keeps the PCB traces from oxidising over time, which makes the traces harder to solder to. | ||
+ | The standard HASL provided by Chinese manufacturers is leaded solder. More expensive options are lead free solder, organic solderable varnish stuff, nickel, or gold flash.\\ | ||
+ | [[https:// | ||
+ | | ||
===== Header plug or socket ===== | ===== Header plug or socket ===== | ||
- | Are plug & sockets primarily for use on PCB boards | + | A header |
{{: | {{: | ||
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- | Waste heat is produced in transistors | + | Waste heat can be produced in semiconductor devices |
{{: | {{: | ||
[[http:// | [[http:// | ||
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- | This is a track detector using an optical system to detect the location of train Merg kit for members | + | This is a track detector |
+ | Merg kit (for members | ||
+ | |||
+ | ===== Hexadecimal or Hex ===== | ||
+ | |||
+ | |||
+ | Computer data is a collection of binary bits, ones and zeros. Programmers generally collect bits into convenient sets of four bits (a nibble) or eight bits (a byte). | ||
+ | |||
+ | When it comes to writing and speaking the values of bits, rather than saying the value is 10010011, it is simpler to break the bits into small chunks and use a different number system. In the past collecting sets of three bits was common (Octal or base 8) but today sets of four bits are generally used (Hexadecimal or base 16). | ||
+ | |||
+ | Binary uses two characters to count before moving/ | ||
+ | |||
+ | You can say the address of a byte of data in memory is at location 0101010010101001 in binary or at 21,673 in decimal. Alternately the binary number is broken into sets of four bits (0101 0100 1010 1001) and each set is converted to a hex number (5 4 A 9). So it can be said that the byte of data is at memory location 54A9. The four digit 54A9 is easier to remember, shorter to say and less error prone to write. | ||
+ | |||
+ | When a hex number is used in a program or written text, it is usually proceeded by some characters to identify which number system you are using. | ||
+ | ASCII Hex encoding | ||
+ | When sending numeric information over a serial link such as RS232 or RS485 it is not possible to send it as raw binary data as some of the possible 256 byte values have special meaning and are used to control the information flow, for an explanation of this see [[glossary_a# | ||
===== High ===== | ===== High ===== | ||
+ | There are situations where there are two levels to a signal, which we commonly refer to as High (1) or Low (0). In the case of logic chips, a high (1 condition) is generally a voltage above 2/3 of the supply voltage. In the case of a transistor device, it may be a voltage high enough to turn a transistor on (to make current flow between emitter and collector). This may require several volts on the base. A low is the opposite condition where a smaller voltage, often near ground, is required to produce a low (0 condition) or turn off a transistor. | ||
- | This what we call greater than the base voltage or ground e.g. so high is 5v ~ 4.4volts above 0 | ||
+ | ===== HO Scale ===== | ||
- | ===== HYPOTRAC ===== | + | Scale and gauge common in America, Asia and Europe but excluding UK. The scale is represented by the ratio 1:87 (3.5mm to the foot). The standard track gauge (width) is 16.5 mm (represents 1/87th of 1435mm). |
+ | ===== Hypotrac ===== | ||
- | This a high voltage track detector system for 2 rail Model railway track , see TB T9/2 merg members only | + | This a high voltage track detector system for 2 rail Model railway track , see TB T09/2 merg members only |
+ | |||
+ | |||
+ | |||
+ | ===== Hysteresis ===== | ||
+ | |||
+ | A common characteristic designed into an electronic circuit is called hysteresis. As an example, you may have noticed that most temperature controls for home heating have a couple of degrees of change between off and on. In order to keep the heater from rapidly/ | ||
+ | |||
+ | A similar effect can be seen in ferromagnetic materials acted on by a magnetic field. When a ferromagnetic material is magnetized in one direction, it will not relax back to zero magnetization when the imposed magnetizing field is removed. It must be driven back to zero by a field in the opposite direction. Because the material retains a magnetic polarity after it is magnetized in one direction it can be said to have memory. This " | ||
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- | Hysteresis is wellknown in ferromagnetic materials. When an external | + | The graph of the magnetic field of a ferromagnetic material, as it is magnetized through both polarities, forms a characteristic loop shape. |
+ | \\ | ||
[[wp> | [[wp> | ||
- | The term is also used to refer to one of the display modules often to be seen on the [[exhibition_stand|MERG exhibition stand]]. This is because the track layout on the module resembles the graph of a [[hysteresisloop|hysteresis loop]]. | + | Within the MERG group, the term is also used to refer to one of the display modules often seen on the [[exhibition_stand|MERG exhibition stand]]. This is because the track layout on the module resembles the graph of a hysteresis loop. |
glossary/glossary_h.txt · Last modified: 2021/08/08 04:50 by Wayne