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H: How does the range of bluetooth increases by adding an antenna?
I have seen too many tutorials on how to increase HC-06 bluetooth module range. They all involve cutting the on-board antenna and adding an external one (a piece of wire or a 2.4GHz antenna). I was wondering how this affects the bleutooth module, for e... |
H: Voltage buffer with ideal Op-Amp (positive feedback) - Instability
I know that the circuits which employ negative feedback are stable, whereas those which employ positive feedback are not stable.
How can I prove that a voltage buffer (ideal op-amp) which uses positive feedback is not stable?
I know only the dual ca... |
H: Large differences between datasheets for the same part number
I'm working with the MIC4605-2 half-bridge MOSFET gate driver. The chip was originally made by Micrel. Microchip has acquired Micrel and took over their product line, including the MIC4605-2.
There's now 2 datasheets for the same part:
The original one f... |
H: Breakout board for EFM8BB1
I am making a breakout board for Silabs EFM8BB1 (Busybee). I have made the schematic but am unsure about the C2 Debug Interface. Can someone guide me please?
AI: You seem to be following the configuration in the application note https://www.silabs.com/documents/public/application-notes/AN... |
H: Problems with DC analysis of a PMOS circuit
I'm beginning with electronics and I've picked up the book from Donald. A. Neamen - Microelectronics. I'm stuck at a simple example of DC analysis for this PMOS circuit.
simulate this circuit – Schematic created using CircuitLab
I have to find:
$$I_D, V_{SG}, V_{SD}$$
Pa... |
H: Driving Stepper Motors
I am currently working on a project that involves 6x NEMA 23 stepper motors, rated at 2.8A - 2.5V each.
I have been doing extensive research on what drivers and power supply I should use. From my knowledge, I have decided to use a 10A, 12V Switching Power Supply, and to use the L298N Stepper... |
H: Can someone explain this op amp "tone control"?
Its supposed to be part of a guitar effect pedal, why is there positive feedback besides the negative feedback? I was reading about op amps and from what i understand positive feedback is very rarely used. How would this affect the signal?
AI: Quite often the way to ... |
H: Level shifter for multiple voltage levels
I found basic level shifters for two different voltages but I have 3 different voltages on my I2C bus.
I just wanted to verify if the schematic below will work correctly. I think it will but I am not sure if the different levels will influence the working.
Would appreciat... |
H: does the battery determines the amount of current flowing in the circuit?
suppose a 9v battery is connected to a load which draws 2 amps of current. so how does the battery determines that load requires this much current ?
I mean if the battery throws about 3 amps, then it would just blow the load, so how the batte... |
H: Video scaling vs Display scaling
I am going to start a project in FPGA and "graphical screen" scaling. I am still in the "reading-the-material-phase".
Are there any differences between video-scaling and display(e.g. Windows Desktop)-scaling?
Video scaling is using Bi-linear,Bi-cubic etc. IEEE got a lot of articles... |
H: ESD and Electrolytics
Consider the simple circuit schematic below:
1) Would a high voltage (say 1kV-25kV) human body ESD discharge event (1ns rise time, 100ns total) at OUT have a negative effect (damage or destroy) the electrolytic capacitor when in the polarity as shown?
2) Do ESD events in general cause issues ... |
H: LED bulb redesign
As a follow up to this question I decided that it is time to see how should I utilize failed LED bulbs. There're 5 of them now, however in different condition - one does not start at all, some start flickering 15 times per second, others start flickering 2 times per second. But those flickering, i... |
H: MPU-9150 (IMU) AD0 address change
I have an MPU-9150 which uses I2C address 0x68 by default, but I'd like it to use address 0x69. This is possible by desoldering the 3-way AD0 "Jumper" on the breakout board. By default there are 3 solder pads and pads 2+3 are connected, so that pin AD0 is defaulting to "ground".
So... |
H: Is there available differential impedance calculation for this stripline configuration?
I am trying to calculate the differential impedance of a differential pair in a 4-layer PCB as follows:
Layer: Low speed signal
Layer: Power plane
Layer: Differential pair
Layer: Ground plane
I am currently using Saturn PCB To... |
H: Damages to ICs done when cleaning boards with IPA
I have designed a PCB and soldered some SMD components on to it. When I check it, it doesn't seem to work. It was my very first SMD soldering experience and I think I used too much hot air. While investigating the issue, I found out a moisture level factor in ICs. S... |
H: Locking header jumper
I want to implement a 3-header jumper setup in order to switch a microcontroller between two video modes on a PCB. I don't want to use just a standard switch as it doesn't seem appropriate for a change which will happen rarely if ever, so I wanted to go with a jumper instead such as this one.
... |
H: Norton equivalent with a single voltage source
I'm trying to find the Norton equivalent with respect to the load resistor RL for the DC circuit below.
Each of the resistors have an equal resistance R. Removing the load resistor, I am having a lot of trouble figuring out which resistors are in series and parallel ... |
H: Why is the capacitance of a short infinite?
The voltage across a short is 0. It also does not store any charge. So the capacitance of a short is 0/0. However, I am told the capacitance of a short is infinite. How can this be?
AI: The voltage across a short circuit is zero, regardless of current.
There are three com... |
H: What are some simple ways to reduce Arduino power usage?
For a quick and dirty project, what are some of the simplest ways to reduce the power use of an Arduino?
Imagine the following setup:
A typical Arduino Nano, hooked up to a pair of DS18B20s and one of the mini OLED screens. Power comes from a cellphone batte... |
H: Any rules of thumb to fix this non-functioning board I just made?
I just reflowed this PCB. It is a 20 x 16 mm PCB with a Nordic nRF52832 Bluetooth Low Energy (BLE) SoC IC. I powered it on and the regulator, mounted on the back, got very hot.
I measured the Vcc and GND outputs of the 3 V regulator and read 50 ohms.... |
H: What are the benefits of this type of JFET biasing
The next schemtaic I was found as an input stage of ultra-linear phono amplifier.
What are the benefits of that type of biasing? I don't see that 12V zener has 12V voltage drop on it (only 4.2V) and in this situation how I can predict the Q-point of JFET?
What JF... |
H: LM2576 in car environment
I have a LCD driver board and it uses LM2576 for voltage regulation/step-down. As being cheap ebay/aliexpress purchase the instructions state 12V DC input without specifying range. Datasheets I found for LM2576 state unregulated input voltage can be up to 40V.
So the question is whether th... |
H: Clarification required on DALI Standard 101,103
I want to develop a complete DALI Control Device with two important features, one being "3 DALI buses on the device" and other being the "RGB colour control feature"! Already, I have successfully designed a DALI Master-Slave prototype system using two STM32s.
As my ne... |
H: How good is to use this zener diode for reverse polarity protection?
In the following circuit how does the zener diode D1 provide reverse polarity protection?
Lets say V+=12V and V-=-12V and the zener is 36V zener.
It means for correct polarity zener will not pass any current since it sees 24V across itself.
But ... |
H: highfrequency signal on ground
I designed a PCB where I have a local oscillator Input to an IC. The LO signal (2.48 GHz) has a power of -20 dBm. I put a cut SMA cable on the ground plane and measured a signal level of -60dBm. Is this normal?
AI: At 2.5 GHz, the wavelength in free space is only about 120 mm or 5 inc... |
H: Why is there a little nose on the PCIe connector?
PCI express cards have an edge connector with a little notch in it to prevent the card from moving if the socket is longer than the connector. Additionally, the printed circuit board has a protrusion in front of the actual connector. What is its purpose?
Depicted ... |
H: Equivalent electrical model for induction motor
For those people who are looking for induction induction motor SPICE model, please follow the link LT SPICE tools and applications
I'm trying to understand the model characteristics and from the image attached, I don't understand what the terms and where they came fr... |
H: Can't program multiple chips using JTAG
SOLVED - LOOK UNDER "EDIT 3" SUBTITLE.
I've got this two chips:
Board with LPC4337(left) and board with ATSAM3X8E(right), JTAG interconnected, using FT2232H chip soldered on the board of the left as an interface.
The first one (LPC4337) can be programmed.
The second one (ATS... |
H: Why are chip designers called "triangle pushers"?
I heard chip designers being described as "triangle pushers," the idea being that somehow the logic on the chip was formulated by arranging triangles on the silicon in certain ways. How does this work? I don't understand how triangles can be arranged to create digit... |
H: Single supply op amp to convert 0-5VDC to +/-2VDC (microcontroller to line level)
I am generating a 0-5 volt sine wave using an arduino with a DAC.
I would like to level shift this signal (DC bias?) by -2.5 volts and have a gain of .8, so that I end up with a line level sine wave.
Thus I am trying to design a singl... |
H: Are internal pull-up resistors in microcontrollers connected to Vcc internally?
I'm partly on my way into my first project with the ATMega32U4 and Im trying to understand the internal pull-up resistor. After lots of research, Im struggling to find an outright answer to my question but from my reading its been impli... |
H: Costs of Conductive Silicone/Rubber Keypad vs. Mechanical Switches?
I am toying around with some new mechanical design ideas. One thing I've never looked at it is the rubber keypads with the conductive "pucks" underneath. I've always used mechanical switches, or overmolded silicone buttons onto the finished enclo... |
H: AD7545JN problems
I have a couple of AD7545JN DACs that I want to drive some proportional vales with, using an Arduino Mega.
My main problems is that I'm only getting about 8V at OUT1 of it with Vref at 10V. And I'm getting some strange noise I can't quite explain.
This is a capture with the Mega ramping up from 0 ... |
H: Can I share a 3-phase motor branch with a small single phase load?
I have a 15hp 3-phase motor on a 50A 120/208 wye circuit. I also have a small 1A dc motor with controller and some monitoring circuits - this secondary system needs 24vdc and 1.5A altogether. I have an ac-dc converter that's rated up to 240VAC an... |
H: Is there any reason that any speaker connected to any computer couldn't be used for listening/surveillance?
I understand that it's possible to use the headphone port of a laptop as a microphone, but what are the physical limitations to using any speaker in the same way?
I'm curious about what makes amplification a ... |
H: Bridge rectifier with no load draws too much current
I have a circuit that includes a bridge rectifier and a transformer.
Values are,
Transformer secondary 4.7v x 2 9.4v AC
Diodes 1n5408 (3A Rectified Output Current)
Rectifier connections are right and i measure from anode anode junction to cathode cathode junctio... |
H: Learning the Art of Electronics - diode clamp
Working through Learning the Art of Electronics, Hayes T, I'm stuck trying to build the diode clamp in Figure 3L.7 on page 137, as below:
The text says to, "Drive it with a sinewave from your
function generator... ...and observe the output." So presumably +ve from the ... |
H: Need to run a mobile robot on batteries
I made a 4wd mobile robot with an 4 DoF robotic arm on it and currently in process of designing a power board for my robot. I would like get a detailed road map on designing a power board for the robot. Here is a brief overview of my hardware:
The robot has 8 joints which ea... |
H: Will a discharge resistor help here?
I have a simple circuit, powering an ESP8266, specifically the esp-12-e.
Connected to the 3.3v coming in I have a 1000uF electrolytic capacitor, to help keep things stable (suggested by the esp8266 community)
It's all working well. However when I cut the power to the board, I se... |
H: Improving the quality of an optical audio transmitter
I wired up a very simple device in which I use an audio signal transformer (EI14) to modulate the intensity of a laser beam (a cheap 650nm, 5mW diode) according to the audio output of my phone. The laser is then received by a photo-resistor (G5528 A205) wired up... |
H: External to internal antenna setup doesn't increase signal power
For a larger project where I basically want to boost phone signals indoors using an external antenna I have devised a small experiment to make sure I get the basics right before I expend a lot of energy.
Basically, I have made an enclosure to reduce s... |
H: About Contactor Lifespan
Newbie here regarding contactors and relays, i had this contactor datasheet https://www.gavazzionline.com/pdf/CC50-CC65.pdf. I'm trying to identify how long the contactor would last and I find the durability category, what's the difference between mechanical and electrical? does the mechani... |
H: DALI Command's reply to the meaning of representatives
I have some control gears which already have short addresses, are connected on DALI lines.
I tried to send Query Short Address (command 269)& verification Short Address (command 268), but I didn't get any response.Is this right?
If above is right, I tried to se... |
H: Can a Z84C00 CPU directly drive 74HCxxx series logic?
I'm getting confused by the datasheet for the Z84C00 CPU, while trying to work out if I can use it to drive 74HCxxx chips, or if I need TTL-compatible logic (i.e. either 74HCTxxx or 74LSxxx). It's clear that the low level voltages are compatible, but I can't wo... |
H: Why am I seeing a low voltage when the switch is open?
I'm building a battery test circuit to check the voltage of the source battery and I've added a Sziklai pair of transistors in as I need to be able to shut off the voltage so that I don't have a low current constantly being drawn while the MCU is asleep. I've ... |
H: Is this circuit linear or not?
I designed a current source circuit for driving LEDs. This circuit works fine and supplies constant 2.5A. I wonder if this circuit is linear or not.
simulate this circuit – Schematic created using CircuitLab
1-) If this circuit is linear;
VLOAD = 9VDC and Vin = 16VDC and VDS-M1 = 6VD... |
H: How does the rollback work in a FIFO?
From reading the book titled "Advanced Chip Design practical examples by verilog", I faced some questions about when the Ethernet packet is read from the FIFO and how the rollback works for the Ethernet packet FIFO.
The chaper 8.3.4 of the book explains the reason why rollback ... |
H: Can I use a battery protection circuit for a 3S 18650 with a LiPo 3S pack?
I am looking into getting a battery protection circuit for the 3S LiPo pack I am planning on using in my project. Max current draw will be 5-6A. Since I think it's more efficient to buy something prebuilt I was looking on aliexpress for some... |
H: What is the relationship between field strength and efficiency in a DC motor?
This refers to a DC motor with permanent magnets.
What is the relationship between the efficiency of the motor and the magnet field strength?
AI: To a first order approximation, none.
Modifying field strength is used as a speed control o... |
H: Can a Li-ion battery be discharged in CV mode?
I have a load which can also be set to "Battery test". I can easily discharge a Li-ion battery using the CC (contant-current) mode, which is also a condition recommended by the manufacturers. For example, a typical recommendation would be:
Discharge CC (18A) to 2.0V ... |
H: Protecting a low voltage (RS485) bidirectional bus from direct mains connection
I have a bunch of devices that will sit on a two-wire bidirectional RS485 bus (DMX-like, but not quite DMX).
I'm trying to protect against an edge case, where a user mis-wires a ballast, and inadvertently connects mains voltage to the b... |
H: Zener Diode vs Precision Voltage Shunt
What is the difference between a zener diode and a precision voltage shunt? From the name I am guessing that the precision voltage shunt is more precise. I am using the shunts to limit the output of a sine wave generator.
AI: If you look at an average zener diode like the MM3Z... |
H: Why is an opamp with single corner frequency more stable?
I read that freq. compensation is done to adjust opamp's corner freq. to single one.
A text mentions:
....
Freq. compensation does that i.e reduces corners to one for stability:
But why is an opamp with single corner frequency more stable than the one with... |
H: Pre-amplifier biased to one-half of power source
There is a schematic of an pre-amplifier that use one-half of voltage source output biasing (T1 emitter is one-half of V1). How the resistive network was calculated to allow one-half output Q-point?
Original link: http://www.zen22142.zen.co.uk/Circuits/Audio/lvpreamp... |
H: High impedance in RTL Verilog
I am designing a shift register. It has a control signal called RD which is asynchronous (so I can't use it inside the procedural block). The whole point is my n-1 bit shift register is value of the input if RD==1 or else it has high impedance; I am not sure how to write the assign the... |
H: Question about the RMS value of the real input power
I've the following circuit:
simulate this circuit – Schematic created using CircuitLab
I know that the relation between the input voltage and the input current is given by:
$$\begin{cases}
\text{V}_{\space\text{in}}\left(t\right)=\text{I}_{\space\text{in}}\lef... |
H: Pole/Zero plot is the same for passive and active (w/ gain) bandpass filter, why?
I have designed an active inverting bandpass filter, and when comparing its pole zero plot to a passive bandpass fitler with the same cutoff frequencys, the pole zero plot is exactly the same, even though the bode plots for both are d... |
H: Lt spice reference signal for plotting
Is there a way to store a signal in LT spice and then plot it on the next simulation run?
I find myself either plotting two runs in an external program all too often, or even using a screen capture to compare different signals.
My tek scope does this, I can store a signal a... |
H: 433MHz receiver compatibilty
Currently I have a setup where a 433MHz Transmitter sends a number from one arduino and a 433MHz receiver picks it up for another arduino. The Transmitter and receiver are of the Super Regenerative type if I'm correct (picture below).
My question is can another type of 433MHz Receiver ... |
H: Rx Intermodulation Implications
I am looking at the product spec of NRF52832, in particular the Radio Electrical Specifications (here, the information is on page 232 of v1.4). Within it is a section called Rx Intermodulation that shows this:
IMD performance, 1 Msps (3MHz, 4MHz, and 5MHz offset) -33 dBm
I ha... |
H: Electric wiring color codes: BROWN, BLUE and BLACK
31.01.2018 16:40 start /
Thank you all for the answers, because this is not a standard wiring plug, i need assistance wiing the wifi adapter in the middle of cable which connect the energy master expert lcd display to the energy master expert plug.
Is this correct... |
H: How to build distance measuring device that can only detect red light from a common red laser
I want to make a distance measuring device. Using common red laser. what receiver should I use to detect the red laser light only? a more sensitive to red light.
Do an Arduino UNO capable of this?
AI: Physical method
A q... |
H: Is a power distribution board just a board that connects all grounds and all positives?
I'm thinking of designing a PCB for a quadcopter but want to directly integrate the power distribution board (power going to the ESCs that power the rotors). I would just like to confirm that it's as simple as connecting all the... |
H: MOSFETs: Gate-to-Source resistor and Gate resistor value calculation
I want to control several Mosfets through a microcontroller. I have a low-power application in mind, therefore the power consumption should be minimized.
When do I need a Gate-Source-Resistor, and when not? How to calculate the value for minimum ... |
H: Delay turn ON circuit using 555
I want to set a delay of around 5s between power supply turning ON and my circuit getting power.
Here is the circuit I have come up with:
Datasheet of mosfet
I am using a 555 timer to set the startup delay and N-channel mosfet to supply power to the load. Most of the through hole ... |
H: How can I use two TP4056 with two li-ion batteries, but single load?
I have two TP4056 modules (with protection circuit), which I am using to charge two batteries respectively, off a single power line. The modules are the ones that have charge output (B+/B-), and another regular output.
I'd like to be able to use b... |
H: truth table for D flip flop with control variables x and y
So I need to build a counter with D Flip-Flop and 2 control variables x and y.
XY=00 --> 0-3-2-1-0;
XY=01 --> 0-1-2-3-0;
XY=10 --> 0-2-3-1-0;
XY=11 --> 0-1-3-2-0.
How should I make the truth table? Should I put for every sequence for x and y the given con... |
H: Should I use MBED of ARM or native platform of microcontroller suppliers?
I got a STM32F429I-DISC1 development board from STMicoelectronics and I know MBED support it.
So if I want to learn about ARM and develop a commercial product in the future, should I use MBED platform or native platform of STMicoelectronics?
... |
H: MFB Analog filter with Reference voltage transfer function
I am looking for the transfer function of the filter below :
This is a multiple feedback second order analog filter, I was already able to calculate the transfer function of the filter without VRef in the positive pin of the op-amp, but I couldn't find it ... |
H: How to test the output current of a LED driver without a LED lamp?
I have very basic knowledge of electronics but I have to design a circuit to control this LED driver (Constant Voltage + Constant Current LED Driver).
I already have a prototype and I need to test it, but I do not have a 20V LED lamp of 40W to check... |
H: Why does speed of DC motor increase when flux is reduced?
I understand that from KVL
e = v -IaRa e=k(flux)speed
speed=(constant)*(V-IaRa)/flux
But physically what causes the speed to increase? What force causes the rotor to accelerate? In fact, physically, the rotor is moving because of field flux interacting wi... |
H: How to create a negative voltage supply?
I am trying to incorporate a LEM LAH 100-P current sensor into a project. It requires a dual polarity voltage supply between +/- 12 and 15 volts. What is the best way to implement it?
Digi-key has an article which references many other application notes. But I don't have kn... |
H: Power up sequence for AD5724
The datasheet says:
POWER-UP SEQUENCE
Because the DAC output voltage is controlled by the voltage
monitor and control block (see Figure 42), it is important to
power the DVCC pin before applying any voltage to the AVDD
and AVSS pins; otherwise, the G1 and G2 transmission gates are at
a... |
H: Logic-Level Converter: How high is the power consumption?
Regarding the following schematic for a bi-directional logic level converter, can someone explain how to calculate power consumption? Can I use pullup resistors with higher values, e.g. 1M?
I need such a converter in my circuit, but the device is battery ope... |
H: Implementing a voltage sensor with voltage dividing resistors
I am implementing a power storage system. The voltage of the storage device must be sensed in order to direct current to and from the storage device.
The storage device voltage will vary between 0 and 60 volts, and the system's current will be up to 60 ... |
H: How does an ARM processor in thumb state execute 32-bit values?
What I understand is, the ARM mode can execute 32-bit of instructions and Thumb mode can execute 16-bit of instructions.
For instance,
Here is the ARM instructions set:
And Thumb instructions set:
From these both instruction set tables, please see A... |
H: If a datasheet doesn't state I2C address pins have pull-up/down resistors, does that mean I must connect them?
I've got a handful of DS75S+ temperature sensors. They're SO-8 and I'm going to solder them onto prototyping boards for use with a Raspberry Pi.
I want to set the addresses sequentially so I have the opt... |
H: common mode choke on DC line
usually common mode chokes are used on AC lines to take care of common mode noise. If I am using a CMC on a DC line ..would the inductance degrade ?
AI: A common mode choke on a DC line will normally be passing some DC current through one winding and the same (but in reverse) DC curren... |
H: p-channel MOSFET switch
I want to use a MOSFET as a switch driven by my microcomputer.
The original circuit using N-channel MOSFET is on the left side. Honestly, I do not understand the choice of the IRLZ44. The circuit is designed for Arduino, which has 5V logic. Which means that for GPIO=True=5V, MOSFET opens... |
H: Convention regarding BJT collector current calculations
Using the equation Ic=Is*e^(Vbe/Vt) yields impossible values for me. I am using Vbe = .7v & Vt = .025 A. Is in circuit is 3.4mA. I am trying to determine Ic as an initial value for analyzing the rest of the circuit, as the rest of the values are unknown. I... |
H: Categorizing ICs as digital or analog
I'm new to electronics and trying to understand the difference between analog and digital ICs. My understand of analog and digital signals is up to scratch but I am struggling to categorize ICs into either analog or digital based on their function.
After digging around in data... |
H: How would you calculate the input and output impedance of this amplifier?
How would you calculate the input and output impedance of this amplifier?
I have done a lot of research and found so many conflicting pieces of
information. Not sure what is right.
C1 = 10Uf, C2 = 1000Uf
R1 = 50KΩ, R2 = 7.5KΩ, R3 = 820Ω, R4 =... |
H: What kind of signal processing circuitry do I need to generate a line level output on an Arduino?
I am trying to create an Arduino based music synthesizer.
How can I safely generate line level output (+/- 2 volts centered at zero, with a frequency range from 20Hz-20KHz) from my Arduino using a minimal number of com... |
H: How can I tell from a datasheet if a thermocouple amplifier IC will work with a grounded thermocouple?
There are several different solution available for thermocouple amplification such as the MAX31856, AD8495, and LTC2983. Some of these support grounded thermocouples (AD8495) and some don't (MAX31856). This is not... |
H: BJT Constant current LED driver
I need to build a constant current driver for a LED with a forward voltage of 3.4V and 350mA maximum current. The driver will be controlled by a PWM signal from a 3.3V MCU.
Reading this post and doing the calculations using my system specs, I came up with the following circuit:
simu... |
H: Creating circuit diagrams from verbal descriptions. (Digital Logic)
I have these two descriptions of systems:
And I want to answer them correctly (comes from a book with no solutions).
For #9, isn't that just going to be an AND gate? We all know the truth table for that.
But #10 is a little more difficult. I'm not... |
H: DC analysis of common-drain NMOS amplifier
The DC analysis is regarding the amplifier calculations, but that is not relevant to the topic. The equivalent DC circuit of the amplifier is:
The known values are: \$R_{g1}=300\text{ k}\Omega\$, \$R_{g2}=200\text{ k}\Omega\$, \$R_s=100\text{ k}\Omega\$, \$k_n=25\ \mu\tex... |
H: How to calculate Fundamental Input Power Factor
I am really confused with the concept of fundamental input factor. What was taught to me in class was the below formula
IPF(Input Power Factor) = IDF(Input Displacement Factor) x CDF (Current Distortion Factor)
Input Displacement Factor was defined by my instructor ... |
H: LED dimming and modulating with two PWM signals
I have a need for an LED, driven by a constant current source, that can be smoothly dimmed and also semi-rapidly (say 2.5kHz) modulated for later bandpass filtering. I've designed a possible circuit, given below. The constant current source and PWM-dimming were alread... |
H: Current limiter for small 12V DC motor
I have a situation where a small DC motor is moving the flap from one side to the other. The flap can be in two positions but without limit switch. Change of position lasts about 3 seconds. The problem occurs when the motor reaches its position, but still has supply. After som... |
H: Buck converter without load - is it dangerous in long term?
As a followup to my previous questions (Q1 - circuit diagram is here, Q2). I disassembled the LED bulbs, cleaned and resoldered the components on the DC-DC converter boards, replaced caps, and chandelier-assembly seems to work well.
Background: Originally ... |
H: Passive RC Lowpass Filter Effects on DC
Connecting passive low pass filters in series and with a load, reduces the dc voltage.
Maybe it is very simple but would you explain a little bit to me about the low pass filter's effects on dc.
Filters don't reduce dc without a load by the way.
Source 12VDC(with little rippl... |
H: Power over Ethernet: AC?
All commercial POE products I have seen feature DC current to power endpoint devices. What are the reason(s) why AC is not used for POE products?
AI: AC is only 70.7% as efficient as DC at transferring power at a given peak Voltage. That is, to provide the same power as 48V DC, you would n... |
H: How can one battery provide multiple voltages
A battery such as this is able to provide multiple different voltages based on user input. Given that the textbook battery provides a fixed voltage, how is this achieved? Are there multiple cells which are connected up together differently depending on the requested vol... |
H: ULN2002A Not turning on?
I ordered a few ULN2002As.
I have it wired as follows:
Pin 1 -> GPIO of Arduino Pro Mini 3.3V
Pin 16 -> 300Ω resistor in series with an LED
Pin 8 -> GND
Pin 9 (COM) -> 5V (which is also RAW for the Arduino).
Pins 1-4 were wired similarly with LEDs but I've removed 2-4 because it wasn't wor... |
H: Differential op amp to measure negative current flow through shunt (Rails set to 0 and 5v)
Note* I have done some searching and though there are related topics to this one, this one is unique and I think it warrants its own Question, especially as asking additional questions on another thread is prohibited.
Measur... |
H: Do the temperature coefficients of the resistors in the LM399/LM199 "Portable Calibrator" significantly effect the output stability?
I'd like to know how voltage reference stability is obtained in products like 6.5 digit multimeters that use LM399 as a voltage reference in spite of using two gain resistors. Let's a... |
H: Mesh Analysis on CCT with Voltage and Current Source
I'm not sure where to apply the supermesh on this problem, would it be over the top mesh and the one containing the current source? I have only tried doing the problem without a supermesh but am not able to get an answer. Without using a supermesh I used KVL in e... |
H: Center tap of transformer for Ethernet interface
When you see Ethernet PHY chips' application circuit, you can find out the difference about connecting center tap of transformer.
Some PHYs should be connect to the DC power but some don't connect to it.
The following circuit diagram is for LAN8720a interface circui... |
H: common mode choke placement in smps
I am designing a hi end SMPS and I have 1 CMC on the input (ac line) and a second on the DC output.
My question is where to place this second CMC.
Usually its best to place filters right at the source of noise. I assume that source of CMN is the secondary output of the transfor... |
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