Electrical Engineering Weekly Newsletter - Monday, June 30, 2014

Top new questions this week: Schottky diode like BJT symbol In this schematic, what do the Schottky diode like "barbs" mean on some of the BJTs where the base is connected? I haven't encountered this symbol before. bjt symbol schottky   asked by jreimers 11 votes answered by hkBattousai 12 votes What's the usage of these holes? I'm really curious to know what are these holes on this mobile PCB: Are these vias? I doubt they are vias. If these are not vias then what are they? What's the usage of these holes? pcb identification   asked by Roh 11 votes answered by Matt Young 18 votes Solder Fumes - Activated Charcoal vs Outside Venting Like probably everyone else here I do a ton of soldering. When I setup my current workshop I built a fume extractor that actually goes in a window near my bench. Basically just a length of dryer duct … soldering   asked by Adam Haile 9 votes answered by MoJo 1 vote 4 layer PCBs with Fritzing Can you use Fritzing to create a 4 layer pcb? Also, in real life, what is the maximum limit of layers we can use to create pcbs? is it 4 layers? pcb pcb-design pcb-layers   asked by user1584421 7 votes answered by PeterJ 10 votes What is purpose of components in this circuit I'm trying to understand this circuit but I can't understand purpose of R4 and R6. Can someone explain their purpose? circuit   asked by user46347 6 votes answered by Spehro Pefhany 4 votes LTC3525 datasheet states that capacitors must be X5R or X7R, not Y5V. Why? I'm selecting parts to build a 3 to 5V boost DC-DC converter using the LTC3525-5. The board I'm planing to build is based on the typical application shown in page 11 of the aforementioned datasheet, … capacitor surface-mount   asked by Ricardo 6 votes answered by Andy aka 13 votes AVR flash memory corruption This question is related to AVR deprogramming itself. Project info: We have a battery powered product using an ATMEGA644P. The application permanently runs in sleep mode and only wakes up once a … microcontroller avr atmega flash failure   asked by Rev1.0 6 votes answered by Jacen 7 votes Greatest hits from previous weeks: Choosing power supply, how to get the voltage and current ratings? Power supplies are available in a wide range of voltage and current ratings. If I have a device that has specific voltage and current ratings, how do those relate to the power ratings I need to … power-supply voltage current   asked by Olin Lathrop 77 votes answered by Olin Lathrop 88 votes Tradeoffs when considering SPI or I2C? What tradeoffs should I consider when deciding to use an SPI or I2C interface? This accelerometer/gyro breakout board is available in two models, one for each interface. Would either one be easier … spi i2c   asked by Mark Harrison 35 votes answered by stevenvh 36 votes Can you answer these? Microwave Oscillator: Both Ports Unstable? I'm just wondering, for microwave oscillators, I think both ports need to be in the transistor's unstable region. What would happen if just one port were in the unstable region and the other in the … oscillator microwave   asked by user968243 1 vote Power origin and power planes placement on PCB Although there are many similar questions to this one, I wish to get your attention to this specific board layout. The main power on the board will be 5V, and one of the layers is dedicated for … power pcb-design ground-plane pcb-layers   asked by Naz 3 votes Digital Latch Circuit with Unknown Outputs Introduction I am a student currently enrolled in a digital course course. I'm actually an analog kind of individual so I (like most other analog people) have a hard time understanding logic. … digital-logic analog latch   asked by user46450 1 vote

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