104 Matching Annotations
  1. Jan 2024
    1. The physicistsStephen Wolfram and Brosl Hasslacher introduced me, in the early1980s, to chaos theory and nonlinear systems. In the 1990s, I learnedabout complex systems from conversations with Danny Hillis, the bi-ologist Stuart Kauffman, the Nobel-laureate physicist Murray Gell-Mann, and others. Most recently, Hasslacher and the electrical engineerand device physicist Mark Reed have been giving me insight into the in-credible possibilities of molecular electronics.

      some of Bill Joy's intellectual history here mirrors much of my own...

  2. Dec 2023
  3. Oct 2023
    1. Two main considerations determine how much capacitance you will need: the required holdup time and the allowable ripple voltage.

      bulk cap selection to PFC

    1. Benefits of Discretes IGBT are high current density and low power dissipation resulting in higher efficiency and smaller heat sink to allow lower overall system cost.

      benefits of IGBT

    1. Features• VCE = 650 V• IC = 40 A• Powerful monolithic diode optimized for ZCS applications• High ruggedness, temperature stable behavior• Very low VCEsat and low Eoff• Easy paralleling capability due to positive temperature coefficient in VCEsat• Low EMI• Low electrical parameters depending (dependence) on temperature• Qualified according to JESD-022 for target applications• Pb-free lead plating; RoHS compliant• Complete product spectrum and PSpice Models: http://www.infineon.com/igbt/

      specs of igbt

    1. Current Loop Feedback Configuration(Sizing of the Current Transformer Turns Ratio and Sense Resistor (RS)

      how to arrange current sense circuit

    2. Similar to other power management devices, whenlaying out the PCB it is important to use star grounding techniques and to keep filter and high frequency bypasscapacitors as close to device pins and ground as possible. To minimize the possibility of interference caused bymagnetic coupling from the boost inductor, the device should be located at least 1 inch away from the boostinductor. TI recommends the device not be placed underneath magnetic elements

      layout guidelines

    3. The bridge rectifier must be rated to carry the full line current. The voltage rating of the bridge should be at least600 V. The bridge rectifier also carries the full inrush current as the bulk capacitor COUT charges when line isconnected.

      bridge rectifier selection

    4. Detailed Design Procedure

      how to design components step by step. There is also a calculation excel for it. https://www.ti.com/tool/download/SLUC114

    5. A resistor-divider network from VREF to GND can easily program the peak current limit voltage on PKLMT,provided the total current out of VREF is less than 2 mA to avoid drooping of the 6-V VREF voltage. TIrecommends a load of less than 0.5 mA, but if the resistance on PKLMT is very high, TI recommends a smallfilter capacitor on PKLMT to avoid operational problems in high-noise environments.

      Peak current limitation with PKLMT

    6. One of the main benefits from the 180° interleaving of phases is significant reductions in the high-frequencyripple components of both the input current and the current into the output capacitor of the PFC preregulator.Compared to that of a single-phase PFC stage of equal power, the reduced ripple on the input current eases theburden of filtering conducted-EMI noise and helps reduce the EMI filter and CIN sizes. Additionally, reduced high-frequency ripple current into the PFC output capacitor, COUT, helps to reduce its size and cost. Furthermore, withreduced ripple and average current in each phase, the boost inductor size can be smaller than in a single-phasedesign

      interleaving means smaller boost inductor, reduced emi ...

    7. The UCC28070 power factor corrector IC controls two CCM (Continuous Conduction Mode) Boost PFC powerstages operating 180° out of phase with each other. This interleaving action reduces the input and output ripplecurrents so that less EMI filtering is needed and allows operation at higher power levels than a non-interleavedsolution.

      overview of UCC28070

    8. RSYN RSYNTH resistance 15 750 kΩRRDM RDM resistance 30 330 kΩ

      Rsynth = Current syntesis down-slope programming. Connect it to VREF disables it. Rdm = Dither magnitude for frequency

    9. Soft-Start and External Fault Interface. Connect a capacitor to GND on this pin to set the soft-start slew ratebased on an internally-fixed, 10-μA current source. The regulation reference voltage for VSENSE is clamped toVSS until VSS exceeds 3 V. Upon recovery from certain fault conditions, a 1-mA current source is present at theSS pin until the SS voltage equals the VSENSE voltage. Pulling the SS pin below 0.6 V immediately disablesboth GDA and GDB outputs.

      fault detection functionality

    1. THE PHASE-SHIFT FULL BRIDGE (PSFB) is a classic topology for applications that must accommodate a wide range of operating voltages, as with battery chargers. A PSFB converter generally uses four power switches (MOSFETs or IGBTs) to form a full bridge on the primary side of an isolation transformer.

      what psfb for

    1. Both the output charge and gate charge are ten times lowerthan with Si, and the reverse recovery charge is almost zero, which is key for high-frequency operations.

      advantage of GaN over Si

    2. The complete switching waveforms are shown in the following figure.

      this is very clear explanation of how PSFB works

    1. From equation (1) we see that under light loading, IL1 is small, so that ZVS operation is not easily achieved, but as the load is increased ZVS operation is more easily realized.

      more load means easier ZVS

    2. As in the explanations of Modes (5) and (6) and Modes (12) and (13), in the lagging leg, if the amount of energy stored in LS is not greater than that stored in COSS for a MOSFET, the MOSFET charging and discharging are not completed, and so ZVS operation is not achieved.

      how to not achieve ZVS

    3. Q2 turns on. At this time DQ2 is conducting, so the Q2 drain-source voltage VDS_Q2 is essentially zero. That is, ZVS operation is achieved, and so a turn-on loss does not occur

      how zvs achieved

    4. Below, operation and current paths for Modes (1) to (14) are described

      how PSFB works step by step

    1. Power dissipation due to OUTPUT slewing during FET turn ON in the recirculation path is given by:PSW3 [W] = (0.5 x VD x IL x VD / SRrise x fPWM) + (0.5 x VD x IL x VD / SRfall x fPWM), where, (4)i. fPWM = PWM switching frequency [Hz]ii. VD = FET body diode forward bias voltage [V]iii. IL = Load current [A]iv. SRrise = Output voltage slew rate during rise [V/sec]v. SRfall = Output voltage slew rate during fall [V/sec]This dissipation is typically not considered as it is quite insignificant.
    2. Power dissipation due to the dead times between switching FETs is given by:PSW2 [W] = (VD x IL x tDEADrisex fPWM) + (VD x IL x tDEADfallx fPWM), where, (3)i. fPWM = PWM switching frequency [Hz]ii. VD = FET body diode forward bias voltage [V]iii. IL = Load current [A]iv. tDEADrise = dead time during rise [sec]v. tDEADfall = dead time during fall [sec]Dead times are necessary to mitigate any risk of current shoot through between the switching powerFETs. Integrated FET drivers often have a feedback based self timed FET switching sequence to ensurethe smallest possible dead times while avoiding any shoot through current.
    3. Power dissipation from conduction loss of each FET due to its on-resistance is given by:PRON [W] = RON × IL2, where, (1)a. RON = FET on-resistance [ohm]b. IL = Load current [A]

      power dissipation from conduction loss

    4. Power dissipation due to output slewing during rising and falling edges is given by:PSW1 [W] = (0.5 x VM x IL x VM / SRrise x fPWM) + (0.5 x VM x IL x VM / SRfall x fPWM), where, (2)i. fPWM = PWM switching frequency [Hz]ii. VM = Supply voltage to the driver [V]iii. IL = Load current [A]iv. SRrise = Output voltage slew rate during rise [V/sec]v. SRfall = Output voltage slew rate during fall [V/sec]Output slewing rate is a balance between EM (Electro magnetic) performance and device powerdissipation.

      power dissipation due to output slewing

  4. May 2023
  5. Dec 2022
  6. Mar 2022
    1. Here is an architecture diagram of the devices I’m currently using

      Architecture of recommended Smart Home products (March 2022)

  7. Feb 2022
  8. Mar 2020
    1. Voltage is the pressure from an electrical circuit's power source that pushes charged electrons (current) through a conducting loop, enabling them to do work such as illuminating a light.

      This is by far the best explanation I found.

  9. Feb 2020
    1. It's like these people walking on the bridge. They are all walking about the same speed, but there are so many more people jostling to cross at the top that the total "current" of bodies is large.
    2. When current flows what actually happens is electrons hop from atom to atom in a kind of long chain, akin to a bucket brigade.
    3. Voltage is the ability to overcome electrical resistance--to get more electrons to flow through a conductor, despite higher electrical resistance. For a loose analogy, think of a person pushing a heavy weight. Higher voltage is equivalent to a person who's stronger, so he can push a heavier weight. Being able to push a heavy weight doesn't necessarily mean he can run particularly fast.
  10. Jan 2020
    1. Alloys[edit] Antimony forms a highly useful alloy with lead, increasing its hardness and mechanical strength. For most applications involving lead, varying amounts of antimony are used as alloying metal. In lead–acid batteries, this addition improves plate strength and charging characteristics.[49][59] For sailboats, lead keels are used as counterweights, ranging from 600 lbs to over 8000 lbs; to improve hardness and tensile strength of the lead keel, antimony is mixed with lead between 2% and 5% by volume. Antimony is used in antifriction alloys (such as Babbitt metal),[60] in bullets and lead shot, electrical cable sheathing, type metal (for example, for linotype printing machines[61]), solder (some "lead-free" solders contain 5% Sb),[62] in pewter,[63] and in hardening alloys with low tin content in the manufacturing of organ pipes. Other applications[edit] Three other applications consume nearly all the rest of the world's supply.[48] One application is as a stabilizer and catalyst for the production of polyethylene terephthalate.[48] Another is as a fining agent to remove microscopic bubbles in glass, mostly for TV screens;[64] antimony ions interact with oxygen, suppressing the tendency of the latter to form bubbles.[65] The third application is pigments.[48] Antimony is increasingly being used in semiconductors as a dopant in n-type silicon wafers[66] for diodes, infrared detectors, and Hall-effect devices. In the 1950s, the emitters and collectors of n-p-n alloy junction transistors were doped with tiny beads of a lead-antimony alloy.[67] Indium antimonide is used as a material for mid-infrared detectors.[68][69][70]

      Potential uses in phone batteries and silicon wafers As semi conductors.

  11. Dec 2019
    1. Made in China 2025, Beijing has designs to dominate cutting-edge technologies like advanced microchips, artificial intelligence and electric cars, among many others, in a decade
  12. Nov 2019
    1. great place to start finding circuit schematic is the Discover Circuits site. They have a comprehensive list of fun circuits to experiment with

      Discover Circuits - more circuits to build

    2. Step 19: Your Third Circuit

      Example of a 3rd circuit to build (check images in post for step by step guide)

    3. Step 18: Your Second Circuit

      Example of a 2nd circuit to build (check images in post for step by step guide)

    4. Step 17: Your First Circuit

      Example of a 1st circuit to build (check images in post for step by step guide)

    5. designed to allow you to be able to insert an integrated circuit into the center

      This way, you can quickly build a circuit (without soldering or twisting wires together)

    6. To use wire in your circuit, simply cut a piece to size, strip a 1/4" of insulation from each end of the wire and use it to connect points together on the breadboard

      Using wire

    7. When things are wired in series, things are wired one after another, such that electricity has to pass through one thing, then the next thing, then the next, and so on

      Wired in series - electricity passing through each thing

    8. circuit is a complete and closed path through which electric current can flow

      Circuit:

      • closed - allows the flow of electricity between power and ground
      • open - breaks the flow of electricity between power and ground
    9. electricity is typically defined as having a voltage and a current rating

      Electricity - typically having voltage and current rating

      but, also - resistance and watts

    10. it is recommended that you use insulated 22awg (22 gauge) solid core wire
      • Red wire - power connection
      • Black wire - ground connection
    11. Wires are nice because they allow you to connect things without adding virtually no resistance to the circuit

      Wires - to connect things together using breadboard

    12. there typically runs two continuous bus lines. One is intended as a power bus and the other is intended as a ground bus

      Two continuous bus lines

    13. They are covered with a grid of holes, which are split into electrically continuous rows. In the central part there are two columns of rows that are side-by-side

      Build of breadboards

    14. Breadboards are special boards for prototyping electronics

      Breadboards

    15. Batteries are represented in a circuit by a series of alternating lines of different length

      Marking of:

      • power
      • ground
      • voltage rating
    16. battery is a container which converts chemical energy into electricity

      Battery - simply stores power

      When put in:

      • series - voltage adds up, current stays the same. For instance, three AA-batteries (1.5V) will result in 4.5V.
      • parallel (rarely) - voltage stays the same, current doubles
    17. This is dependent on the type of switch it is

      Types of switches:

      • Normally open (N.O.) - close circuit when activated
      • Normally closed (N.C.) - open circuit when activated
      • single-pole double-throw (SPDT) - both open one connection and close another when activated
      • double-pole double-throw (DPDT) - two SPDTs combined. Break two separate circuits and open two other ones, every time the switch is activated
    18. switch is basically a mechanical device that creates a break in a circuit. When you activate the switch, it opens or closes the circuit

      Switch - open/close the circuit

    19. it is ideal to light up multiple LEDs by wiring them in parallel

      Prefer to light up LEDs in parallel over series

    20. Like all diodes, LEDs create a voltage drop in the circuit, but typically do not add much resistance

      To prevent short circuit created by LEDs, you need to add a resistor in series: calculate how much resistance is needed for a single LED (use slightly larger value than calculated)

    21. special type of diode that lights up when electricity passes through it. Like all diodes, the LED is polarized and electricity is only intended to pass through in one direction

      LED (light emitting diode):

      • polarized (like all diodes)
      • electricity intends to pass only through one direction
    22. For instance, if you have two 10K resistors in series between power (5V) and ground (0V), the point where these two resistors meet will be half the power supply (2.5V) because both of the resistors have identical values

      [Power] --(5V)-- [10K Resistor] --(2.5V)-- [10K Resistor] --(0V)-- [Ground]

      • 2.5V as we have two identical resistors
      • as we turn the knob in potentiometer, the 2.5V can shift towards 5V or 0V
    23. current is rated in Amps

      Current = Amps

    24. integrated circuit is an entire specialized circuit that has been miniaturized and fit onto one small chip with each leg of the chip connecting to a point within the circuit. These miniaturized circuits typically consist of components such as transistors, resistors, and diodes

      Integrated circuit

    25. PNP transistors allow electricity to pass from the emitter pin to the collector pin

      PNP:

      emmiter ---> collector

    26. NPN transistors allow electricity to pass from the collector pin to the emitter pin

      NPN transistors:

      collector ---> emitter

    27. transistor takes in a small electrical current at its base pin and amplifies it such that a much larger current can pass between its collector and emitter pins. The amount of current that passes between these two pins is proportional to the voltage being applied at the base pin

      Transistor

    28. the other side connects to power

      Anode

    29. The ring found on one end of the diode indicates the side of the diode which connects to ground

      Cathode

    30. Diodes are components which are polarized. They only allow electrical current to pass through them in one direction. This is useful in that it can be placed in a circuit to prevent electricity from flowing in the wrong direction

      Diodes

    31. Ceramic disc capacitors are non-polarized, meaning that electricity can pass through them no matter how they are inserted in the circuit

      Ceramic disc capacitors = non-polarized

      Typically marked with a number code to be decoded

      Typically represented as two parallel lines

    32. Electrolytic capacitors are typically polarized. This means that one leg needs to be connected to the ground side of the circuit and the other leg must be connected to power. If it is connected backwards, it won't work correctly

      Electrolytic capacitors = typically polarised

      Written on them:

      • Value typically represented with uF
      • minus symbol (-) representing leg connecting to the ground

      Represented by side-by-side straight and curved line

    33. capacitor is a component that stores electricity and then discharges it into the circuit when there is a drop in electricity

      Capacitor

    34. With alternating current, the direction electricity flows throughout the circuit is constantly reversing

      Electricity flows in AC:

      reversing (alternating direction) throughout the circuit

    35. resistors add resistance to the circuit and reduces the flow of electrical current. It is represented in a circuit diagram as a pointy squiggle with a value next to it

      Resistors:

      • measured in ohms
      • come with different wattage ratings
    36. electricity in a circuit must be used

      IMPORTANT consideration!

    37. With Direct Current, electricity flows in one direction between power and ground

      Electricity flows in DC:

      one direction between power and ground

    38. Potentiometers are measured in ohms like resistors, but rather than having color bands, they have their value rating written directly on them (i.e. "1M"). They are also marked with an "A" or a "B, " which indicated the type of response curve it has

      Potentiometers are measured in ohms (like resistors).

      Written on them:

      • value rating (i.e. "1M")
      • type of response curve it has ("A" or "B"):

      "A" - logarithmic response curve (1, 10, 100...) {increases logarithmically}

      "B" - linear response curve (10, 20, 30...) {increases evenly}

    39. Potentiometers are variable resistors. In plain English, they have some sort of knob or slider that you turn or push to change resistance in a circuit. If you have ever used a volume knob on a stereo or a sliding light dimmer, then you have used a potentiometer

      Potentiometer - changes resistance in a circuit

    40. The round notch on one edge of the IC chip indicates the top of the chip. The pin to the top left of the chip is considered pin 1. From pin 1, you read sequentially down the side until you reach the bottom (i.e. pin 1, pin 2, pin 3..). Once at the bottom, you move across to the opposite side

      Order of reading pins in the IC chip (1 to 8):

    41. As a beginner, you will be mainly working with DIP chips. These have pins for through-hole mounting. As you get more advanced, you may consider SMT chips which are surface mount soldered to one side of a circuit board

      Study from DIP chips to SMT chips

    42. you can learn all about integrated circuits by looking up their datasheets. On the datasheet you will learn the functionality of each pin. It should also state the voltage and current ratings of both the chip itself and each individual pin

      Find more information about integrated circuits in the datasheets

    43. There are two basic types of transistors, which are NPN and PNP

      2 basic types of transistors: NPN and PNP. They have opposite polarity between collector and emitter.

    44. They are represented in schematic as a line with a triangle pointing at it

      Representations of diodes:

      • line = connects to the ground
      • bottom of the triangle = connects to power
    45. it requires energy to pass through a diode and this results in a drop of voltage. This is typically a loss of about 0.7V

      Drop of voltage (important when talking about LEDs - special form of diodes)

    46. The most commonly encountered types of capacitors are ceramic disc capacitors that look like tiny M&Ms with two wires sticking out of them and electrolytic capacitors that look more like small cylindrical tubes with two wires coming out the bottom (or sometimes each end)

      Typical look of capacitors

    47. Capacitors are measured in Farads
      • picofarad (pF)
      • nanofarad (nF)
      • microfarad (uF)

      conversion chart

    48. Any resistor of over 1000 ohms is typically shorted using the letter K. For instance, 1,000 would be 1K

      1000 ohms = 1K

      1 000 000 ohms = 1M

    49. Anyhow... a resistor with the markings brown, black, orange, gold will translate as follows: 1 (brown) 0 (black) x 1,000 = 10,000 with a tolerance of +/- 5%

      Sample calculation of resistance

    50. You read the values from left to right towards the (typically) gold band
      • 1st two colors = resistor value
      • 3rd color = multiplier
      • 4th (gold band) = tolerance or precision of component

      You can tell the value of each color by looking at the color value chart, or by using graphical resistance calculator

    51. two different ways in which you can wire things together called series and parallel

      2 different ways to wire things

    52. switch does not add any resistance to a circuit and simply adding a switch between power and ground will create a short circuit

      Switch doesn't prevent short circuit

    53. Always make sure that you never accidentally connect positive voltage to ground while wiring things in parallel

      IMPORTANT!

    54. electricity always follows the path of least resistance to ground

      Having choice, positive voltage will pass through wire straight to ground, instead of motor to ground

    55. It is very important to prevent short circuits by making sure that the positive voltage is never wired directly to ground

      IMPORTANT!

    56. Shorts are bad because they will result in your battery and/or circuit overheating, breaking, catching on fire, and/or exploding

      Short circuits are bad

    57. there needs to be something wired between positive and ground that adds resistance to the flow of electricity and uses it up. If positive voltage is connected directly to ground and does not first pass through something that adds resistance, like a motor, this will result in a short circuit

      Resistance - prevents short circuit from happening

    58. Voltage is obviously rated in Volts

      Voltage = Volts

    59. There are two types of electrical  signals , those being alternating current (AC), and direct current (DC)

      2 types of electrical signals:

      • Alternating Current (AC)
      • Direct Current (DC)
    60. The rate of reversal is measured in Hertz, which is the number of reversals per second

      Hertz = number of reversals per second

  13. Jul 2018
    1. Figure 3: Motor system with flip switch and potentiometer

      Please add a wiring diagram that would allow someone to reproduce this circuit.

  14. Nov 2017
  15. Apr 2017
    1. “The current measures are not an acceptable long-term solution to whatever threat they are trying to mitigate. Even in the short term it is difficult to understand their effectiveness. And the commercial distortions they create are severe,” said IATA director general Alexandre de Juniac.

      Hard to understand what any of this achieves...

  16. Apr 2016
    1. Great Principles of Computing<br> Peter J. Denning, Craig H. Martell

      This is a book about the whole of computing—its algorithms, architectures, and designs.

      Denning and Martell divide the great principles of computing into six categories: communication, computation, coordination, recollection, evaluation, and design.

      "Programmers have the largest impact when they are designers; otherwise, they are just coders for someone else's design."

  17. Feb 2016
    1. Design-Oriented Analysis Rules and Tools, Dr. R. David Middlebrook

      Real problems usually have more variables than equations. So approximations and inequalities are essential.

  18. Jan 2016
    1. A thorough primer on C programming, specifically for the Texas Instruments TM4C123 or TM4C1294 microcontrollers. By Jonathan Valvano and Ramesh Yerraballi of UT Austin.

  19. Dec 2015