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H: Smart Card (SIM) clocking requirements
I'm trying to implement a SIM card interface using TI TM4C123XL. I have a question about a clock. TI MCU seems to provide possibility to interface smart cards but don't let me multiply clock without multiplying baud rate. So it seems to me I will have to generate the clock usi... |
H: Circuit analysis on op-amp with no negative feedback
In this diagram, there's an op-amp with no negative feedback. What is V+ (voltage at positive end of op-amp)?
I'm self-learning circuits, and a resource I'm using says V+ = V3 / 2R. However, I don't understand why it's V3 / 2R. I know V3 is the voltage source thu... |
H: direction of a VQFN pinout IC
I want to use the
TCA9548A in QFN format, I have diffuclties understanding the direction of pins, is it here really in clockwise ? as shown in page 33 of the datasheet ?
AI: Page 33 is a dimensional drawing. ICs with a proper datasheet will contain a "Pin Configuration" section that... |
H: Op-amp symmetrical triangular wave
Im using op amps to generate a triangular wave, my ultimate goal will be to power motors using pulse width modulation.
The problem is that the triangle wave is saw toothed instead of symmetrical.
Why is this? what mistake have i made in my circuit?
AI: The problem is that the tria... |
H: Is it safe to control a DC motor's RPM with rapidly turning on/off?
Would it safe (no overheating or equipment damage) to control a DC motor (gear head in particular) by rapidly turning it on and off? For example, if I have a 500 RPM motor and I was 250 RPM, could I turn it on for 1 ms then off for 1 ms, repeat? If... |
H: LiPo battery low voltage alert
I have a microcontroller (ATmega328) powered by a single cell lipo battery. I would like to make the microcontroller know when the battery voltage gets under a given level (someting around 3.5V) to output some kind of "low battery" alert.
Can I do that without using another battery? D... |
H: How to determine point of failure in photodiode circuit
I have a photodiode circuit which uses a fiberoptic pigtail photodiode as shown in the picture below:
The photodiode is connected to an opamp as in the circuit below:
The supply rails for the opamp are +2V and -38V.
The situation I am having is that sometime... |
H: CCFL wire polarity; any considerations?
Are there any considerations for the polarity of wires on a CCFL tube?
I am converting a monitor from 120vAC to 12vDC using a generic inverter (AVT4029; also have AVT4168 not pictured) and LCD driver board. The CCFL tubes are encased in the assembled display (Samsung LTM230H... |
H: Why am I getting signs of high RF radiation, while the desktop computer turns off?
The desktop computer doesn't have any Wi-Fi accessories. The keyboard and the mouse are wired. But even when the computer and the LCD monitor are turned off
(while the power plugs are still connected), I get a high frequency signal ... |
H: Why do I get constant voltage across load of single phase inverter even with increasing input voltage?
I built a single phase inverter, as shown below. However, for PWM gate control signal of maximum 9V peak, I noticed that the output PWM voltage across the a 10k resistive load does not increase above 6V no matter... |
H: Battery Holder for 3.7V 3000mAh 18650 Li-ion AAA?
I am interested in using 3.7V 3000mAh 18650 Li-ion AAA batteries (e.g. EBL). However, users indicate (reading the reviews) that those batteries are not the same size as traditional AAA.
I was going to purchase a standard AAA holder (e.g. 4 X AAA Holder), but now I... |
H: Does the PID Controller (LOVE 16C-3) Need an External SSR?
My PID controller LOVE 16C-3 has a output of "relay".
Do I connect the output of the PID controller to the inputs of an external SSR?
Or is the relay already built in into the PID controller?
AI: The relay output is SPST rated at 5A:
You cannot use this... |
H: Understanding Working of LC Meter
I am trying to understand working principle of the circuit given in the link below :
http://kripton2035.free.fr/Resources/lcmetersch.pdf
I realized that the circuit is basically relaxation oscillator with LC tank circuit attached to its non-inverting input. I know that when the ou... |
H: Steps to hand draw Bode magnitude plot for a particular transfer function
Can anyone guide me through how to hand draw a correct Bode magnitude plot for
$$G(s) = \dfrac{48000}{s(s+0.1)(s+100)}$$
Don't even need phase plot, just need correct magnitude plot
As few calculation needed as possible, in other words, just... |
H: 3.3V/5V Linear Regulator Voltage to Ground Jumper
I received this 3.3V or 5V power supply. It's neat because it fits on my breadboard and can provide two separate voltages (chosen using jumpers) on it's two outputs. I originally thought that this was a Step-Down Converter, however, it's been pointed out to be a L... |
H: How to interpret packaging information in Datasheet
I'm trying to create a part for Fritzing and I am struggling to interpret the packaging size in the datasheet.
In the notes it is said that the sizes are in mm, ok with that, but how should these numbers be interpreted? A division or max/min does not make sense.
... |
H: How does voltage progress during discharge of a battery?
The build:
I'm building a portable bluetooth boombox.
It's a very simple build. The components I'm using are:
Bluetooth amplifier board (TDA7492P)
2x50W speakers
Rechargeable battery
The amplifier needs to receive 12V. So the battery I will get will be able... |
H: Different square waves from one microcontroller
I'm doing a project and I need the microcontroller (ATmega328) to do these two things:
Generate a rectangular wave to be filtered and obtain a DC voltage (that varies linearly with the duty cycle)
Generate a square wave (50% duty cycle) with a certain period
The mic... |
H: Max input current of DC DC converter
I'm not sure if this is the right place to ask this kind of question(mine seems practical as opposed to academic) but here it goes.
The embedded board I am using(Jetson TX1) can be powered using:
4S LiPO(4 cell / 14.8V nominal / 16.8V charged) with 1-2A (or 15W) of
continuous ... |
H: Common Source JFET Amplifier
I am trying to build a simple JFET common source amplifier to get about 5-10 times gain for a signal I have coming from a microphone with an amplifier already in it, from ADA Fruit, here
I am working with a circuit just like below, but with the capacitor on the output removed.
I have ... |
H: How the MOSFETs driven by a six winding transformer
I have a 6 winding transformer of 1:1:1:1:1:1 as shown in figure. And connected to V1 and V2 MOSFETs. DRV and DRVGND are fed from a HCPL 3120 driver.
My questions are
1) Is it acting like a 1:2 transformer for mosfets?
2) Why do we fed from one terminal of prim... |
H: SIM900 not getting powered on
I have a circuit where I am using a SIM900 GSM/GPRS module. As per the datasheet it needs 3.4 V - 4.8 V and upto 2 A of current. I am using LM2576. The input to the regulator is 12 V & 4.2 A and output (which is going to SIM900) is 4.175 V. I have connected leds for NETLIGHT and STATUS... |
H: Energy calculation for a short circuit of a battery
I have a battery cell with the given datasheet: WB-LYP100AHA
So I can calculate the short circuit current with the internal resistance as:
$$ \frac{3.5V}{0.00045Ohm} = 7777.78A $$
So the internal power generated is:
$$7777.78A^2*0.00045Ohm = 27222.23W$$
Energy ... |
H: Splitting Power Tracks/Planes into Different Layers
I'm just wondering that, in terms of EMC/EMI, what the effect of splitting a power track/plane into different layers can be.
Assume a power track/plane/pour area (with enough thickness and/or total area for, say, 5A DC) is split into two tracks/planes/pour areas (... |
H: How to find cutoff frequency with more than one resistor
I have the above circuit and I want to find the cutoff frequency. Z_eff,in is my load. I have created a transfer function:
How is it possible to find the cutoff frequency? Let me know if more information is needed.
AI: You can find the cut-off frequency eve... |
H: Free Electron in Current
An electric current is a flow of free electrons. Are these free electrons totally free from the orbits of metal atom or they moving by jumping from one orbit to another orbit of the atoms?
If they are totally free, what does enforce them to keep staying in (or on the sufrace of) the metal
T... |
H: Instanciating blocks in VHDL, asignment of clock and reset signals
I am trying to connect 5 stacks together using VHDL below. The main problem I am facing is that that I don't know how to deal with the signals clk which stands for clock and rst which is asynchronous reset and the SOp stack operation signal-vector w... |
H: Convert 12V 200mA to 5V 450mA
I am making a transformer-less AC to Dc power supply and the best design that I have got till now is this:-
For better understanding you can download this PDF:-
www.nxp.com/documents/user_manual/UM10522.pdf
This circuit uses a TEA1721 ic to convert AC Mains voltage to DC voltage. Thi... |
H: Unable to understand the details of step-down voltage regulator
I have currently purchased a 'Pololu 5V, 2.5A Step-Down Voltage Regulator D24V22F5' to regulate my 12v into 5v. This so far works fine!
The thing I'm wondering about it, and looking at the diagram and schematics of the device:
I need some help figurin... |
H: How do I link two components from different files in VHDL?
Sorry for the amount of code in advance (I added the code since I was unsure whether it is needed here to resolve my issue).
My main goal is to link two components which are in two separate .vhd files together in a block in a third file.
Lets say that I hav... |
H: hamonics and sidebands in dc-dc converter
The lecture (page 8) shows output voltage spectrum with sinusoidal modulation of duty cycle of a dc-dc converter.
I am wondering where the hamonics and sidebands come from.
For hamonics, I read somewhere that because converter power stage is non-linear
so it generates ha... |
H: Multisim - how to view Op-Amp Voltage Saturation
multisim-print
Hello! I am learning electronics in university and need to get the Voltage Saturation for this Amp-Op circuit (it might be easy but I don't know how to do it...), the print above also has the DC Sweep graph.
If you need more info I'll give it, sorry if... |
H: Danger from NOT connecting cables
We have a new LED roof-lamp at our home and I ordered a matching dimmer-switch to replace one switch in a 3-way-switching. To have matching wall-elements, I also ordered a replacement for a normal toggle-switch (for another roof-lamp) and a normal power-outlet in the same "wall-gro... |
H: Why does a buffer op-amp need two feedback paths?
I am designing a linear voltage source. I have a precision volatge reference (REF5050 by TI), and before I do anything with its output I buffer it. However, the datasheet of the amplifier I use (OPA197) suggests the following:
This brings up the question - why are ... |
H: Calculating Fuse Size
A time lapse camera rig I'm, working on needs an appropriate fuse. The camera will be powered by a 12 volt deep cycle marine battery. The instructables that I'm using to build this rig is found here.
The camera I'm using is the same as in the instrutables: 8 V, with an unknown wattage.
I bough... |
H: How do I get the PIR sensor to output more than 3.3v?
I have a setup where I have a 12V source and a PIR sensor like the one pictured (below) and some LED strips that are rated at 12V that I've mounted under the stair railings. The problem I've hit is that the pir sensor only outputs 3.3V when triggered.
In extreme... |
H: Clock termination considerations, single clock driving multiple loads
In the following example, a single clock is driving two loads.
The traces to the loads have different lengths (10mm and 30mm).
It is not feasible to make the individual routing lengths equal.
Clock specification:
Frequency: 25Mhz, Output: HCMOS, ... |
H: Selecting Voltage Divider Resistor and OpAmp For Temp Sensing With NTC Thermistor
I've been doing some reading on here about measuring temperature with NTC thermistors and using the Steinhart-Hart Equation.
However I am still a bit confused about the selection of a resistor to put in a voltage divider with the ther... |
H: Designing Switching Circuit for Raspberry Pi 3 Project
I'm working on a simple RPi project wherein I can control my garage door with my phone via Tasker. I am using an RPi to connect to my wifi network and power on a remote garage door opener. My current setup is to short out the button on the remote and use the RP... |
H: Why is root mean square used when calculating average power, and not simply the average of voltage/current?
$$P = I_{\text{eff}}^2 \times R$$ where \$I_{\text{eff}}\$ is the effective current. For power to be average \$I\$ must be average current, so I am surmising that the effective current is the average current.... |
H: How to convert mm to xy coordiantes in pcb xy files
i have few pcb gerber projects which come along xy files in txt/xlsx format , these xy files have x y values in mm/inches/mils for every element on the board.
am developing gerber editor for gerber files which will search for elements on that baord.
what i have do... |
H: Can closed metal box work as a wave-guide for wireless transmitter?
I am using NRF24L01 and ZigBee modules for wireless communication. I kept the modules in the tapered closed aluminum cylinder for sensor data transmission. The signal was being received when the module was placed at some specific positions (closed ... |
H: strange symbol on a green capacitor!! what's it?
I have plenty amount of capacitor with a strange symbol on them. I tried google but I could not decode those capacitors. that symbol looks chinese but like english alphabet "H". I need help
AI: Judging by the size of the capacitor and the markings I'm willing to be... |
H: led lights resistor
I recently installed an H7 Led Headlight kit 12V/25W in place of a standard halogen 55w bulb. Lights are great, but they flash periodically during can-bus Cold/Warm checks to see if a bulb is out.
I was advised to install a 55Watt 6Ω Resistor that will prevent the LEDs from flickering during ch... |
H: TVS diode before or behind resistor
The best way to protect AVR pin for me is RC filter and TVS diode but I don't know one thing. I've seen schematics where TVS diode was before RC filter like in first schematics.
simulate this circuit – Schematic created using CircuitLab
But before resistor it is larger current... |
H: Switching power between LEDs with common ground
For light our light filter we need to have RGB LEDs that are controlled via 50% duty cycle 1kHz square wave from arduino micro controller.
Since there are 4 RGB LEDs connected in parallel they draw a lot of current that is given by an external source. We decided to ... |
H: RS Flipflop Truthtable for Q=1 and Q* = 0
I am studying Computer Science and I am very confused.
Let us say our Q is 1 and our Q* (Negation of Q) is 0. So when we go for R = 1 and S = 0, why isn't the value of Q* = 0?
I mean the NOR Gate for Q gives us Q = 0, which makes sense for me. But why is this value taken ... |
H: Voltage Supply Circuit
I am trying to supply my circuit from this part. I have two different supplies which are VUSB_5V and VORG_5V. My aim is when one of two comes to circuit, this supply does not go to other one or effect it to prevent a dangerous situation. If both supplies are available, the bigger one should b... |
H: Assigning values to multiple outputs syntax problem - `,` or `;`
I want to assign multiple values to signals as shown in example below. Do I separate values there by ; or ,?
Example:
opcode : process (OP)
begin
case OP is
when CALL => AOp <= "000", -- am I separating right?
AL... |
H: 4-Pin programming interface
Could anybody give me a hint on how to wire a proprietary device, that uses a Nordic NRF51822 chip and only provides the following pins: {3.3V, GND, RST, CLK} to a programmer. I am pretty sure it is using SWD, but I don't know where to attach the DIO pin to.
AI: nRF51822 for sure uses SW... |
H: Why can I use P = I²R but not P=V²/R when calculating energy lost in a circuit?
I am working through a book of problems and am confused by the answer to this one:
A 12 V battery supplies 60 A for 2 seconds.
The total resistance of the wires in the circuit is 0.01 Ohm.
Q1. What is the total power supplied?
Q2. What ... |
H: How does a PC sound card be able to detect 433 MHz signals?
I have developed a radio driver that can detect sensor RF packets for a particular protocol, in 433 MHz band using a 433 MHz receiver module like this one and also similar to this one. Before I started with the software implementation, I was given a sound ... |
H: How to calculate the time that a piece of wire can last before it melts when constant current is applied
How to calculate the time that a piece of wire can last before it melts when constant current is applied?
Assume it has a fixed cross-sectional area, I know longer the wire quicker it will melt, but whats the m... |
H: Strange op-amp circuit using LM324
I built a simple op-amp circuit using LM324 (SO-14 package). The structure of the circuit is shown below and Vout = 1.65 + 3.3*Vi. I first used 3.3V single power supply as Vcc and applied a signal 0.125+0.125*sin(t) to Vi. The Vout was suppose to be 2.0625 + 0.4125*sin(t). However... |
H: How do loose connections cause overheating, arcing and start a fires?
I am confused as to how a conductor can became overheated when it's connection to the circuit is unintentionally loosened.
A loose connection will cause the resistance to increase and decrease the current. Why does the temperature increase if the... |
H: Voltage divider types question
I have been studying different schematics ive found online to try to get a better understandment on the subject. Recently I came a voltage divider across that consisted of a transistor and a resistor, it looked something like this.
I am only familiar with a voltage divider that cons... |
H: BGA decoupling capacitors placement
I am trying to figure something apparently basic and I hope somebody might give me an advice.
The IC I am working with is XC6SLX25. It has 6 different power regions -- Vccint, Vccaux and Vcc for each of the four banks. Xilinx provides a PCB design guide (UG393) where they specify... |
H: How is this small drone able to transmit video to such long distances? And that too an HD video?
I am an amateur enthusiast and a novice, thus please bear with me.
I was having the look at the http://www.proxdynamics.com/products/pd-100-black-hornet-prs drone. It weighs 18 grams and is able to transmit HD quality v... |
H: How to correctly configure deepsleep for STM32L0xx
I'm trying to configure my Nucleo Board with a STM32L073RZ in deepsleep mode to get the lowest power consumption.
To do that I use the mbed librairies with the deepsleep() function (This function use Stop mode with RTC). On the application note given by STMicroelec... |
H: How to calculate baud rate and determine the number of stop bits in asynchronous serial
Below is the given question:
For my understanding, 1/baud_rate = 104.16
However, when I tried to do reverse division, the result is so different than expected.
My calculation to find baud rate:
1/104.16 =9.6006 * 10^-3
Is m... |
H: How to creat a clock for a flip flop
I have a project in Discrete Math and we have to apply some switching theory with it. I've had studied different type of flip flops (JK, SR, and D) and still confused about the clock component. I know flip-flops are edge triggered. But the problem is applying this to my circuit.... |
H: RJ45 jack to PCB
Everyone, hello!
So I'm building a PCB in my head right now, and I just wanted to quickly eliminate a thought I had in my mind.
When I add a RJ45 jack connector to my PCB board, there are (depending on how the connector is build, of course (with LED or not, etc)) normally 8 PINs for the 8 wires in ... |
H: How would I connect very fine wire (0.005") to a PCB?
Let's say I have very fine gauge wire of 0.005" (0.127 mm) diameter.
This wire is completely exposed (i.e. no insulation). What are available methods for terminating this to a PCB? Searching through Digikey and Mouser, the smallest gauge terminal blocks I could... |
H: How to get LiPo battery protection circuit's function and schematic
I have three single cell 500-730 mAh LiPo batteries at home. I would like to know if they have an on-cell protection circuit (I can see it in one of them, and I think the others also have it) and what this circuit exactly does. If possible I would ... |
H: Average power across a resistor
I am solving a problem here that asks for average power across a resistor.... the resistor is 3k and V(s) = 1.897sin(500t - 71.6)...
I found 0.8 mW ....but the answer book says that it is 0.6mW ...
isnt it ... (Vrms)^2 over 3k ?
Vrms = 1.897/sqrt(2)?
***if A = 1.987 ... the power com... |
H: Looking for elliptical display or modular display to approximate ellipse
I'm not very fluent in electrical engineering so please bear with my imagination.
Requirements: Photo realistic display, touch screen, approx 7x3 feet (2.1 m x 0.9 m).
Option 1: Do elliptical displays exist? Whether it be a tv or monitor or w... |
H: Deciphering Thin Copper and Fabric Wires in Cable
I'm planning on connecting a Nintendo Wii Classic controller directly to IC2 input on a RP2 board.
The controller I'd like to use is a Black Wii Classic Controller.
Here's some photos of the Controller cable. I need to figure out which of the smaller cables will n... |
H: Convert 3.3V PWM of Beaglbone black to 5V PWM
I have a Beaglebone Black revC. I want to use a brushless motor (EMAX XA2212/1400KV) with ESC (hobbywing skywalker 20) . Beaglebones Vpp voltage is 3.3V and ESC gives ( gives beep about 2 sec interval) "Throttle signal is irregular" trouble signal. I think this ESC acce... |
H: What does an ideal phase response look like for a single port SAW resonator?
I've been struggling to find an example of an ideal phase response for a single port SAW resonator. In particular, I'm looking for a graph similar to this one:
which shows the admittance/conductance and phase response of a BAW resonator, ... |
H: Soldering generic AC/DC to 4 pin plug
So, long story short: I'll soon have a PCB which accepts 24v 5a power input and has a 4 pin power plug of this type:
And is wired like this:
My question is: assuming I have a generic AC/DC adapter with the correct voltage and amperage and I cut its plug, if I were to solder i... |
H: Problems with IRF520 Transistor
This is the schematic for the project. I'm using an IRF520 transistor (http://www.futurlec.com/Transistors/IRF520.shtml) which goes from left to right Gate->Drain->Source. So the problem is that when gate is connected to a pin on the arduino the transistor will always be open regard... |
H: CR2450 Battery at 2.95 Volts
If the open circuit voltage of a 3V CR2450 Battery is at 2.95 Volts: is it at end of life?
I have a CR2032 3V that could fit in the device and I could use a nickel to compensate to fill the gap in the device: is there any foreseeable problem in doing this?
Update: installed a CR2032 as ... |
H: Waveform to (5V) rectangle
I've found some interesting electronic projects which I wanna build, but I'll need a frequency meter for at least 1MHz. Sadly, I don't own one, but I found on the web that an Arduino UNO could do it.
My problem is that AVR's and other microcontrollers like 0V-5V logic levels as inputs, so... |
H: What does the radiation from an antenna look like?
Just out of curiosity, I searched for antenna on Google Images, and what usually shows is something like this. So I really thought that an antenna radiates in a circular and equal pattern. But as I read the specs of an antenna and understand terms like DBI and Pola... |
H: 3-state buffer mechanism
I read about the 3-state buffer. I do not precisely understand the working mechanism. It allows essentially to obtain a third state, that corresponding to the disconnection of the output from the circuit (eg. a bus).
This disconnection of what exactly it consists?
In what sense the corre... |
H: Do any microcontrollers allow steering of inputs to outputs?
Are there any MCUs which allow input signals to be connected (by software) to outputs?
The main requirement is that should not involve sampling (either by MCU code or SCTimers) as this limits the speed of the steered signal to that of the MCU.
The signals... |
H: Boost converter help
First, the problem I am trying to solve:
My objective is to create a device that will generate a constant current to a load that varies in resistance from approximately 1Kohm-40Kohm. I will be using two 6V batteries in series as my main source to create a 12V source. For the sake of this questi... |
H: Oscilloscope to monitor AVR
I'm at the point where I'm stuck on communication issue and thinking on finally getting an oscilloscope. To my beginner surprise, wasn't expecting them to be so extremely expensive, so I was looking around and found old school oscilloscope for super cheap.
The guy who is selling the scop... |
H: Double CMOS inverter time constant
The problem involves finding the time constant for the circuit that arises when the switch is flipped to the U position. What excactly is happening here? I am having trouble visualizing what is going on with the capacitors once the flip happens.
(And what about flipping it to the... |
H: Do packages have to be centered in eagle to export valid pick and place data?
I am working on a PCB featuring this SD card connector
http://media.digikey.com/pdf/Data%20Sheets/Amphenol%20PDFs/101-00313.pdf
In the technical drawing, it seems that the origin of the part is the intersection of the axis of the compone... |
H: Which ARM Cortex M chips allow for execution from RAM?
I've been playing around with writing operating system-like software, mostly as a self learning experience. I've been doing this on the Atmel AVR processor, since it's simple enough for me to understand and get a program going quickly. I now want to move into... |
H: Why do 1 pF capacitors exist?
What kind of uses do engineers find for 1 pF or lower-value capacitors?
This is the kind of value one gets with two bits of wire close to each other or two tracks.
AI: The smallest capacitor I've used recently, in a filter in a 6 GHz receiver, was 0.5 pF. There were some 2 nH inductors... |
H: Best circuit to play music in car, using ISO 10487
instead of using a radio, I want to install a Raspberry Pi 3 with my own features in the 2Din Slot, so I have to make my own circuit to play audio. I tried with the following modules based in LM386 pic:
It doesn't work bad at all, but neither good enough, the max ... |
H: Can a standard computer function as a radio receiver without additional hardware, and how?
Can a standard computer function as a radio receiver without additional hardware, and how?
Thanks, and happy holidays.
AI: Short answer: No. You can often however get it to transmit radio, even if you don't want it to.
Long a... |
H: Why is there a non-zero phase error in a second-order PLL?
Why is there a non-zero phase error in a second order PLL even though there is an integrator in the loop (type-1 system)? The same transfer function is applicable whether frequency or phase is considered as the input. Why then, under locked condition,steady... |
H: Generate Short negative pulse from an open collector output?
Ive been teaching myself as I go so please forgive me for any errors. I need the output of an open collector output (goes to ground when active) to henerate a short negative pulse to reset the counter at 6 so it counts 0-5.
I am using a 2 74142 nixie dri... |
H: Why higher frequency processors use more power?
Why higher frequency processors use more power?
A higher frequency processor would solve the task in less time, thus increasing idle time and thus reducing power consumption.
This would compensate the fact that it uses more power.
What's wrong in my reasoning?
AI: If ... |
H: How can I get rid of this spike in my overvoltage protection circuit?
simulate this circuit – Schematic created using CircuitLab
I am trying to design an overvoltage protection circuit. And this is the circuit above, and this is the LtSpice circuit below:
This circuit somehow manages to function correctly. Meanin... |
H: What happens if you add a voltage source to the output of an op-amp?
I'm trying to self-learn EE and have a question:
What happens if you add an external voltage source to the output of an op-amp? Say as in this picture:
I know that WITHOUT the Va, Vout would just be Vin (is this a correct assumption? I'm assuming... |
H: Convert ps/2 to usb using ttl to usb converter
I have an old keyboard that has ps/2 interface. I have a ttl(V G tx rx) to usb converter too. Can i use this converter to connecting my keyboard to USB port?
What about RS232/RS485 to USB converter? Can i use that to this convertion and connection?
AI: I have a ttl(V... |
H: How to prevent eagle from attempting a specific route?
I'm using the eagle autorouter to route my PCB because it makes cleaner tracks than if I did it myself. One problem I have is that sometimes it insists on attempting to make the same connection over and over again even though in the end the connection is not op... |
H: Finding an unknown resistance with superposition
I've been given a problem in which I need to calculate the resistance of an unknown resister \$R_2\$ by using the superposition method. The only other info which I have is that \$R_2\$ needs to be such so that \$I_1=I_2\$ and \$I_3=20\text{ mA}\$.
I hope the image is... |
H: Driver for a 2 digit 7 segment display
I have two 7-segment displays (datasheet here). They are common cathode. The forward voltage for each segment is 2.0 V. The continuous forward current is 25 mA. What I'm looking for is a relatively inexpensive ($3-$4 or less) IC that can drive both of these, using a microco... |
H: What component can transfer heat from cold to hot?
I'm sure I've read about this somewhere but I can't remember where and my Google search all seems to be too genetic to find what I'm looking for.
I'm looking for a component that uses electricity to move heat from one face to another (with the possibility of cold f... |
H: Possibility of using 5A 5-220VDC Solid State Relay for switching 120VAC String Lights
I have purchased this Relay Board http://www.sainsmart.com/sainsmart-8-ch-ssr-5a-dc-dc-5v-220v-solid-state-relay.html
This board uses a mager GJ-5FA-L relay with input ranging from 3-32VDC and a coil switching range of 5-220VDC at... |
H: LED strip negative wire connected from the end
Recently I ordered some christmas led ligths from China, and I wanted to mess with it a bit (dimming, cutting it to parts), and i noticed that it is wired differently than I expected.
It seems that the negative wire is carried all the way to the last LED and only then ... |
H: Can the 741's offset null pins be grounded?
... Or should I leave them not connected if I'm not going to trim them?
I think I fried an LM741 when it's output was only connected to a single MOSFET's gate (and the single supply was <12V). The only thing I can figure is it's bad to ground those offset null pins, but I... |
H: Can I overvolt a motor when the current stays within the limits?
I have a 12V 0.24A computer fan. When I supply it with the 12V, it drains something like 0.17A. Can I increase the voltage until the current reaches 0.24A or will it destroy the motor?
AI: A well designed 12V BLDC fan ought to be able to run 6~16V. T... |
H: Doesn't GHDL support infinite clock generation in testbench?
I'm having a problem with a clock generation in GHDL. I'm trying to simulate an infinite (in terms of simulation time) clock, but the command in GHDL to analyze (-a) the VHD got stucked. Here is the code:
library IEEE;
use IEEE.std_logic_1164.ALL;
--... |
H: How to plot the phase response of a transfer function
I am trying to plot the phase response of a box with an unknown transfer function by by measuring the phase difference between the input and output at different frequencies but I am not exactly sure of how to plot the phase response with the data obtained.
So I... |
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