Differences

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--- glossary:glossary_d [2013/04/10 10:44] – [DPST] controlpanelman
+++ glossary:glossary_d [2018/01/29 06:23] – Added the Debounce entry Wayne
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 A D type connector is usually with 9 or 25 pins to connect computer cables. It is in two parts. A socket or female connector and a male plug. It is known as a D type connector due to the D shape of the surround to the pins and socket.
+===== DC =====
+Direct Current. DC is the unidirectional flow of electric charge. Direct current is produced by sources such as batteries, a model train set controller or a dynamo on your bicycle. Typical DC voltage values used on model train layouts are 12V (locomotives and Printed Circuit Boards ([[glossary:glossary_p&#PCB|PCB]])), 5V ([[glossary:glossary_s&#Servo|servo]]s and logic circuits such as those used by [[glossary:glossary_c&#CBus|CBus]]) and 2-3V (Light-Emmitting Diode ([[glossary:glossary_l#led|LED]]) illumination).
+More information about DC: [[https://en.wikipedia.org/wiki/Direct_current|Wikipedia - DC]]
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-===== DCC Digital Command Control =====
+===== DCC =====
-DCC Digital Command Control systems, both analogue and digital, allow you to simulate prototypical train operation on your model railroad. With Digital Command Control you can operate multiple locomotives independently at the same time on the same section of track without a computer and without blocking or other complex wiring schemes. Digital Command Control systems use digital data packets to communicate commands to decoders that control locomotives and turnouts on the railroad.     \\ What will it do for me and my railroad?     \\ Simply put, DCC will let you "run your trains, not your track." DCC gives you the freedom to bring your railroad to life! With DCC you have truly prototypical operation at your fingertips.     \\ Why use a digital system rather than an analoge system?     \\ Because digital technology gives extremely reliable operation and the technology is almost infinitely extendable without causing backward compatibility problems (analoge systems are inherently more restrictive). Also, digital systems make wiring simple and easy to install. Because a digital system encodes information sent from the command station to the decoder as numbers grouped into packets, new types of packets can be added to a digital system to send more information thus extending the existing system without causing backward compatibility problems.
+Digital Command Control. DCC systems allow you to simulate prototypical train operation on your model railroad. With DCC you can operate multiple locomotives independently at the same time on the same section of track without a computer and without blocking or other complex wiring schemes. DCC systems use digital data packets to communicate commands to decoders that control locomotives and turnouts on the railroad.     \\ What will it do for me and my railroad?     \\ Simply put, DCC will let you "run your trains, not your track." DCC gives you the freedom to bring your railroad to life! With DCC you have truly prototypical operation at your fingertips.     \\ Why use a digital system rather than an analoge system?     \\ Because digital technology gives extremely reliable operation and the technology is almost infinitely extendable without causing backward compatibility problems (analoge systems are inherently more restrictive). Also, digital systems make wiring simple and easy to install. Because a digital system encodes information sent from the command station to the decoder as numbers grouped into packets, new types of packets can be added to a digital system to send more information thus extending the existing system without causing backward compatibility problems.
+===== Debounce =====
+Most mechanical switches and relays have springy contacts that can bounce when thrown. This will deliver multiple pulses to the electronics and play havoc when a circuit or software only wants to see one pulse or step in the signal. The classic cure is to add a delay of several 10s of Milliseconds after the first step so repeats can be ignored. The delay length can vary according to known switch parameters. Nowadays that is most easily done in the software and is typically called Debounce delay.
+For hard-wired logic in CMOS, TTL etc, with no software, the usual method of trapping bounces is to add a bistable between the switch and main input.
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-Digitrax is a sullpier of DCC systems located in Norcross, Georgia (just outside Atlanta).  They supply a full range of command stations, decoders and accessories.     \\ For website see links page
+Digitrax is a supplier of DCC systems located in Norcross, Georgia (just outside Atlanta).  They supply a full range of command stations, decoders and accessories.     \\ For their website see [[http://www.digitrax.com/|Digitrax]]
 ===== DIL =====
+Dual In Line sockets. A DIL socket is usually plastic for soldering to a printed circuit board to receive the pins of a computer chip. \\ [[http://en.wikipedia.org/wiki/Dual_in-line_package|Wikipedia - DIL]]
-Dual in line sockets DIL. A socket usually plastic for soldering to a printed circuit board to receive the pins of a computer chip.
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 The DIODE is an electronic component that allows the passage of current in only one direction.     \\ [[:glossary:diode|Main article]]
+===== Dirty PSU =====
+"Dirty" PSU is BBC Engineer speak for a good, regulated and clean power supply that has a dirty job to do.....supplying relays, servos etc.\\
+ If the feed wires from PSU to load are of sufficient length to have a bit of impedance and supply several loads, then the dirt caused by one load can cross to other loads. This would usually be positive & negative sharp spikes superimposed on the dc. If the PSU is inadequate and feeds clean and dirty loads then the effects can also cause Pic ( or other microprocessor ) "brown-outs" which may force a re-boot or even more subtle disturbances to your previously happy data digits.\\
+ The separation of the digital low current circuitry with a separate "clean" PSU is one of the classic precautions to be observed ( as you and we all are frequently reminded on the MERG forum! )
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-DPR Double Pole Relay - In spite of all the advances in electronic components over the past few years, there is still no realisticalternative to the electro-mechanical relay. This is especially the case when the voltages or currents to be switched bear no relation to the circuitry switching them. Similarly, the ‘Changeover Switch’ arrangement is not easy (or economical) to implement in solid state form. Analogue Switches are available, but are generally only suitable for ‘small signal’ circuitry such as Audio/Video equipment.     \\ The module shown here provides eight independent double pole changeover relays, mainly intended for track section switching, frog polarity switching etc, although they can be used for any desired function within the specification of the relays. The module is designed to be Control Panel mounted, as part of an RPC (remote panel control) system by a MERG member.
+DPR Double Pole Relay module from the RPC range.     \\ In spite of all the advances in electronic components over the past few years, there is still no realistic alternative to the electro-mechanical relay. This is especially the case when the voltages or currents to be switched bear no relation to the circuitry switching them. Similarly, the ‘Changeover Switch’ arrangement is not easy (or economical) to implement in solid state form. Analogue Switches are available, but are generally only suitable for ‘small signal’ circuitry such as Audio/Video equipment.     \\ The DPR module provides eight independent double pole changeover relays, mainly intended for track section switching, frog polarity switching etc, although they can be used for any desired function within the specification of the relays. The module is designed to be Control Panel mounted, as part of an RPC (Remote Panel Control) system.