A look at an old AVR (Automatic Voltage Regulator) PCB that I was asked if I could fix. these devices are used in generators to regulate the output voltage, which they do by varying the DC excitation of the rotating (rotor) central core of a generator. A generator works by spinning a polarised magnetic field inside an external (stator) group of coils to induce current in them as an alternating AC waveform. By varying the magnetic field of the internal rotor by applying DC current via slip rings, you can adjust the voltage generated.
In this case the AVR (Automatic Voltage Regulator) is powered by the output voltage and also uses it to monitor voltage and frequency. It doesn’t regulate the frequency, since that is done by the device rotating the generator, but it can detect if it’s dropping too low and stop applying excitation for protection against high current flow. It monitors the voltage and compares it to a set value to determine if DC excitation of the rotor is required, and if it is then this unit uses a thyristor to switch the power to the rotors excitation coil on one half of the output waveform.
The operation of these generators generally requires a residual magnetic field in the rotor to even start producing electricity, so if a generator has not been used in a long time and that field has diminished too low to induce enough current in the output (stator) windings to provide its own excitation current, then it is sometimes necessary to disconnect the excitation windings and apply a DC current briefly (often from a starter battery) with the correct polarity to put in a base magnetic field to get the system running again. This is called flashing.
This video also shows how some fairly innocent passive components can fail as opposed to the more common active components. In this case it was a resistor that was being used well within its rating, but failed in a manner that left no obvious sign of the damage you normally see with less passive resistor failure.
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China Al Circuit Board Provider Directory 2017
A-TECH CIRCUITS CO.,LIMITED
According to : http://www.atechcircuit.com/about-us
A-TECH CIRCUITS CO.,LIMITED is a contract PC Board fabricating firm based in Shenzhen China, which focus on quick turn PC Board prototype, small to medium volume PC Board fabricating and assy services. It’s founded in 2003, with around 550 professional full-time employees, we’re qualified to achieve yield 15,000 square metre(s) per month, including around 3000 types of rapid PC Board prototype. The PC Board (printed circuit board) we produced are widely utilized for diverse electronic industries, which include computer peripheral devices, aerospace, telecom, automobiles, medical devices, cameras, optoelectronic products etcetera. Around 80% of our PC Board products are exported to Europe, North America and Asian countries.
A-Tech Circuits always stays with the thought of “quality first, on-time delivery and consumer satisfaction”. Since we consentrate on level of quality, pricing, on time delivery and continuous enhancement, we can fulfill specific needs from international high tech corporations. Further, We are already accredited : ISO9001:2008, ISO14001, TS16949 & UL (UL No: E357001) and likewise complied with the RoHs & WEEE requirement of leadless PC Board products thru SGS test.
We comprehend that there’s definitely a lot of competition in the PC Board industry, but we’re confident that our commitment of high-quality, service and quick turnaround times place us before the curve. Not merely will we demonstrate that we’re worth your business and belief, but also we will let you know how come our buyers generally return.
To be able to satisfy different shopper needs across the globe, A-TECH presents an vast selection of PC Board fabrication and service, below is a list of the services and products we now present:
Rigid FR4 PC Board
Flexible PC Board
Rigid-flex PC Board
Metal Core / LED PC Board
Micro-wave / RF PC Board
HDI PC Board
PC Board Assy
Make Contact With Us
A-Tech Circuits Co., Ltd.
Address: JiaYu Building, ShaJiang Rd, SongGang Town, Bao’an District, ShenZhen , China.
Tel: 86 (0) 755 3326 0657
Fax: 86 (0) 755 2306 4829
Inbox: [email protected]
UNI PRECISION INDUSTRIAL Hong Kong
For well over Three decades Uni Precision has offered excellent contract manufacture services to buyers around the world. Our company offers engineering support, production automation, logistics operations and a number of contract manufacturing features.
Superior quality & Good Value – PC Board Outsourced Manufacturing Accommodating operations and professional customer service network hashelped Uni Precision to become one of the most renowned contract manufacturers in China. We work to extend past expected values for consignment, entire and tailor-made manufacturing services.
Superior Inspection & Complying
Diverse Manufacturing Capabilities
Buyers all over the globe try Uni Precision for quality design and contract manufacturing services. Our proficient operations, cheap operating costs and pro logistics administration reduces fees and offers good value to our purchasers.
Situated in Hong Kong, with a 7,500 sqm ( 80,700 sq. ft.) manufacturing plant is positioned in Dongguan, China. With beyond 600 workers and advanced manufacturing hardware, we offer unmatched quality, qualification and value. Uni Precision was one of the first-batch service providers in China to get hold of ISO 9001:2008, and we have carried on to increase our quality certificates to satisfy the higher level of qualification and trustworthiness.
We’re A Contract Maker in China Having Global Sales Support
Uni Precision attempts to exceed customer anticipations. Our key company culture is committed to providing the finest quality engineering and contract manufacturing services, even if customers frequently select Uni Precision for our service & support. With sales workplaces in Hong Kong and on the West Coast of the U.S ., we offer effective customer care and very clear conversation throughout the PC Board assembly process.
As being a China’s leading contract manufacturers, we are able to limit customers’ publicity and danger by working with suppliers directly. We comprehend the Chinese culture, language and legislation, and will work to guarantee quality, qualification and matchless value. We comprehend export demands and hold relationships with significant shipping companies that support timely delivery.
Versatile PC Board Contract Manufacturing Committed To High quality
Our qualified employees is centered on eminence, with a operation team that concentrates on frequent training, open communications and group interaction. Our organization culture is devoted to quality and effectiveness, and is prepared to work with you to provide a solution for your PC Board demands. Uni Precision assists several of the most innovative high-tech enterprises, and is in a position to make it easier to lower costs simply by contract manufacturing services.
Communicate with Uni Precision today to find out more about us or to request for a quotation. We are one of the most well-known contract manufacturers in China, and are able to give unrivaled superiority and cost.
Get a hold of Us
Uni Precision Industrial Limited
Room 1303, Tower One, Harbour Centre
1 Hok Cheung Street, Hunghom
Kowloon, Hong Kong
E-mail: [email protected]
Hong Kong Headquarter
Telephone number: (852) 2356 5800
Fax: (852) 2364 9336
E-mail: [email protected]
Ourpcb Tech Ltd.
As stated by : http://www.ourpcb.com/about-us
OurPCB is a international PC Board fab & assembling company that supplies Overseas service and support by utilizing our capabilities.
You can expect competing prices, quality service and support and superb delivery time period. We do that because we’re the manufacturing company. OurPCB Tech, Our main corporation in China was founded in 2005, and has provided high quality PC Board fab and Assemblage services for a lot more than 2,500 buyers throughout the globe. As a way to gratify our consumers’various needs and standards for PC Board assembling, We created our own PC Board assembling factory in April 2011.
Our manufacturing area has improved machinery, however, not only three high-speed SMT lines, Siemens HS50 Pick and placers, Siemens F5 pick and placers, Heller 1809 Reflows, Speedline MPM printers, OK intelligent solder irons, And Otek AOI devices to name some. We support BGA, QFN, QFP, DIP and LGA SIP assembly forms.., The most miniscule SMT footprint we can mount is 0201. Our plant also can offer you programming, Wiring along with injecting and conformal coating services.
Our Assemblage factory has ISO9001 Accreditations, For bare PC Board manufacture, additionally we have ISO and UL certificates., Hence OurPCB is highly good at handling / Producing fine quality assembling projects that satisfy today’s superior quality standards.
Touch base with Us
OurPCB Australia PTY LTD
Electronic mail: firstname.lastname@example.org
Position: Suite 3A, 85 Bardia Avenue,Seaford VIC 3198
Ourpcb Tech Ltd.
Electronic mail: email@example.com
Telephone : 86-311-85981900 86-311-85981877
Position: 3rd Floor,Nanhai Plaza,NO.505 Xinhua Road Xinhua Area, Shijiazhuang Hebei China
Position: #1,Xinke industry Yard, Yunkai Road, Luquan economic&industry development district, Shijiazhuang Hebei China
MultiTech Electron HK Ltd. (PCBwell.com website)
With MultiTech set up in 2006, our company has been aimed towards providing exceptional service and awesome charge for PCB Vast amounts fab and Electronic Circuit Board prototype fab. We produce printed circuit board prototypes to a max of 16 layers. With several years of experience in circuit board industry, our workshop has used up 7,300 sqms, with over 420 working people, the productivity total capacity per month is over 10,000 sample projects with more than 25,000 sqms on volume production. MultiTech is one in all the reputable providers in China to supply excellent quality and 100% solid circuit boards, primarily aim for High-end and High-Exactness prototype PCBs, and small-to-medium sized fab, our boards are largely used in Health care, Telecommunications, Industrial Control, Computer system, Aeronautics & Astronautics, and Defense & military areas. With scientific management, solid and steady quality, outstanding technique and qualified service, MultiTech has achieved progressively more acknowledgement from world-wide buyers as well as many other circuit board OEM.
At the same time, MultiTech has received the certifications such as ISO9001:2008, UL (No:E362511), ROHS, at this point we’re making an application for TS16949 and qualification for Military use.
MultiTech is capable to fabricate 1 To16 layers PCBs, aspect ratio is 26 : 1, the max finish board thickness is 4.0 mm, max copper thickness is 12 ounces, min mechanical drilling hole size is 0.10 mm, min laser drilling hole size is 3mil, min line width / line space is 2.0/2.0mil. We have rich experience in making Heavy Copper Board, Mixed Board, High Frequency Board, High TG, High Precision Impedance Controlled Board, Flex-semi Board, Flex Board and many more.
Delivery time that are required: 24-hour delivery for double-sided boards, 72 hrs for 4-Layer PCBs, we’re devoted to providing PCBs
promptly with the very best price, making our purchasers to diminish their production expenditure and crucial development period, this will be great for them to get additional market shares.
Communicate with Us
Location : HuangTian No.2 Industrial Zone, Bao’an Dist, Shenzhen City, PRC
Telephone Number : 86-760-88290182
Fax : 86-760-88290182
Email Address : firstname.lastname@example.org
Skype ID: email@example.com
Dependent on : http://www.pcbwell.com/about