texts: As a computer science engineering graduate, do I need to learn Assembly language in today's day and age?

texts:
Given that there are simple and easy to learn/use MCU devices such as those offered by Arduino, Particle, TI (MSP430 series), Microchip (PIC16 series) does it make sense to teach ALP to computer science engineering (CSE) students or for them to learn it?

The way many of my peers and I learnt to use MCU was by actually writing embedded C code and playing around with MCU offering of the companies mentioned above. While some were hobby projects, many were application oriented. Nowhere did we use ALP to configure the MCU.

How does it benefit them to learn the basics of assembly level programming as part of their engineering curriculum? Is there something I'm not accounting for which assists students to learn this subject better?


texts: ADC Machine Monitoring System w/ External Voltage Source

texts:
I've got what I hope to be a simple question for all of you!

Let me preface with a little background. We are constructing an ADC circuit used in conjunction with a Raspberry PI to monitor cycles of some industrial machines. If a constant Voltage, Say Vi is sent to the machine, Vi will be returned if the machine is not in cycle, and a lesser voltage, Vo if it is.

To give a bit more detail on the machines, they are industrial plastic injection machines. They are all equipped with a small circuit which I've shown below. When the machine is not running, no current is flowing back from Vin. When the machine is running, the transistor is triggered, so some Vout < Vin is returned. Below is an image of the circuit that is used in the machine:

Where Din and Dout are the input & output from our circuit, and Min and Mout are the raw voltages from the machine. The machine itself outputs 0V to Min when not running, and about 24V when running.

The warehouse is currently using a control system which, if we tap into the voltage differentials between the Vin & Vout to the machines, the circuit is quite simple. However, we need to remove the control system entirely so that isn't an option. We discovered that the impedance of the PI isn't enough to get accurate readings so an external voltage source is necessary for what we need, which leads us to my questions today.

Here is a drawing of the circuit which I believe should do the trick:

where M0 - M6 represents the machines, and R0 = R1 = R2 ... = R7

A quick thing to note: the software I developed for this analyzes dV/dT to determine peaks and valleys so specific voltages are not required.

Here are my questions / concerns:

From Kirchoff's law, I believe the voltages sent to the machines will all be the same. Will the current be the same, or will the current draw when the machines are running throw off the other channels?
Does it make sense to attach Vref of the ADC to a channel from the external source?
Should the Analog Ground of the ADC be connected to ground of the external source?
Will we need to use any series references / OP Amps for this type of circuit?

Thank you in advance for any help. Please bare with me as I am EE noob (Software dude here).


texts: Will this crystal-driven inverter successfully produce AC current?

texts:
The basic idea of this  is that the crystal X1 and filtering caps C1 and C2, will produce a simple square wave that feeds into the NPN transistor Q1. When Q1 is on, the input voltage that Q2 and Q4 are dependent on is 0, and is 12V when on the other side of the cycle. Q2 serves as a NOT gate for the FET Q3, thus inverting the current state of the FET Q4. This makes it so that as long as the circuit is on (has sufficient power), the FETs will always oppose each other and produce a sine wave.

My questions:

What are the current flaws in this design?
Will the crystal be able to handle the input of this transistor? I don't know how many watts are needed to drive a transistor, or how many can be supplied from a crystal.
What should the ideal values of R1 and R2 be? I was thinking anywhere between 25k and 75k would be sufficient.
Is there a way to tune this circuit so that I could find the resonating frequency of the transformer?
is there a maximum frequency that X1 can produce?


texts:
We must move from WM8731SEFL to WM8731CSEFL, as the original part is obsolete.

I am advised the only difference is the "introduction of copper bond wires".

  Order Code WM8731LSEFL and WM8731LSELF/R changed to WM8731CLSEFL and WM8731CLSEFL/R to reflect change to copper wire bonding.

What is a copper bond wire?  Does it refer to the interconnects, the solder pads or something else?  Could the change affect RF emissions?


texts: How to find out T1H, T1L, T0H and T0L for ledstrip WS2813?

texts:
I have bought a led strip WS2813 from AliExpress. It does not have a decent datasheet with all details, neither does the seller knows about.

I tried different settings (for what I could find at some datasheets for WS2813), but none seem to work.

Than I tried to use 4 potentiometers which I used to vary the 4 times (T1H..T0L). However, I couldn't get e.g. a full red or green light. Probably the timing is incorrect.

Is there an 'easy' way to find out these times?

I used 'nop' assembly statements for delay, but when using the potentiometers I used a for loop which gives about a 50 ns minimum delay/accuracy, which should be ok.


texts: Tips for Cross checking baudrate of usart

texts:
I'm trying with blue tooth module HC05 with pic controller here and i would like to check my cross check my  baud rate via scope or simulation.

I would like to know the steps or good methods that you guys do while ensuring proper usart communication and baudrate.

One method I trust I could follow is to do with scope :).And Proteus would be the least preferred.
I would like to have your point of thinking to have a learning for me.


texts: Value is a duplicate in Altium Designer BOM

texts:
I'm using ActiveBOM in Altium Designer 19.  My design has 100k 5% resistors and also has 100k 1% resistors.  ActiveBOM gives an informational warning (an "i" with a white circle around it) that the value 100k is a duplicate.  I'd like to clear this error.

I'd guess there's a way to suppress this error in Project Options, but I don't want to do that because finding duplicate parts is a good feature.

I could also change the 'Value' field of one of the parts, but that doesn't seem right because they both actually are 100k.

I guess I could change my use of the resistor value field to include the tolerance, but that seems like it might mess up simulation (which I haven't started using yet).

What's the best way?


texts: What do the numbers on a zener diode signify

texts: I have a zener diode obtained by reverse engineering, there is an icon of what is surely the mathematical model, and there are two numbers 41 and underneath 48, what do these signify?


texts: ETSI EN 300 220-1 868MHz frequency precision

texts:
I'm trying to read the ETSI standard regarding my 868MHz transmitter design.

I would like to transmit in one of the channelized bands ex. (868.600 to 868.700), which has a demand on 25KHz channel spacing.  This sets a huge demand on the frequency error of the system. See table 5 of EN300 220-1.

A crystal of +/-10ppm would result in frequency error of +/- 8680Hz at 868MHz. So this does not leave much space in the channel for modulation of the carrier, and sets high demands on the modulation not spreading into the adjacent channels.

So, I was looking into high precision crystals, like +/-5ppm but these seems expensive, around 3USD which is more than my transmitter IC.

Does there exist any low cost, but high precision 10-12MHz oscillators that can be used for this purpose ?


texts:
Is it possible to detect specific UVB wavelength ranges using just a UVM-30A UV sensor or similar.

The spec sheet for sensor GUVA-S12SD.

Seems to indicate that it generates a specific current level when sensing a specific wavelength, but because its sensing a range of wavelengths
I guess you get the summation?

Is it possible to use any techniques to perform a UV spectral analysis
on the output so as to detect the presence of a specific wavelength band.

It also important to determine relative intensity over time for the band.
Is this anyway possible?

I'm not a physicist, but I can do any programming necessary.


texts: conduction current vs displacement current across capacitor

texts:
Kindly help me understand the difference between conduction current and displacement current. Quick searches explain that displacement current is associated with changing electric field, frankly speaking, it is too technical for me to understand.

Also, please relate it to why Capacitor allows AC and blocks DC. They say time varying voltage(AC) produces displacement current which can flow through the insulator while fixed voltage(DC) produces conduction current which cannot flow through the insulator. This is what made me put this question to you.

Thanks in advance.


texts:
I'd just like to preface this by saying I'm a complete newbie with electrics, so please bear with me.

I just went out and bought a battery pack for my RC Car controller as well as a balance charger. The battery pack is an 8 cell NiCd pack, which as labeled as "9.6v 650mAh" (although I doubt quite a lot that the entire pack is only rated 650mAh). I knew the battery would not be charged off the bat, so I quickly got home, plugged in this charger and started reading the manual. This is where my problem starts.

The manual is in very poorly translated English, and it seems to expect that you have prior experience with chargers and such.

After some fumbling, I figured out that I needed to give it a charging current (which can range from .1A to 6A). I went with what seemed to be the safest option of 0.1A and let it go. It then started a cycle of charge-rest-charge-rest and so on. I have no idea of knowing when it is fully charged and didn't want to risk it, so after about 5 minutes of having the battery on the charger I unplugged it and put it in my controller, which has a battery voltage readout. It said 11.7V, which was more or less the voltage I got when I used to put in 8 separate conventional NiMh rechargable AAs. I thought that was good enough and started playing with the trim on my RC car. Very soon afterwards my control started beeping indicating the battery was low. It's now on about 8.9V.

So I'm assuming I either gave it the wrong charging current or I took it off before it was fully charged (or both). Can anyone give me a crash course on do's/dont's or a formula of what charging current I should use and how I should charge this battery?


texts: Leaving a RC servo motor idle for long term?

texts:
I've been searching for awhile and can't find an answer so hopefully someone here can help me :)

I just want to know if leaving a servo motor idle, powered but no input, is bad for it? I'm planning on leaving a servo motor powered indefinitely and only sending it a signal to move a bit maybe once a day.

I was trying to setup something with a relay so my microcontroller can control the power to the servo but it's a little bit of a pain, not that it can't be done.

So, should I definitely not leave my servo motor powered for days/weeks?
Thanks!


texts: AC/DC Power adapter plug: difference between center positive/negative

texts:
Why are some power adapters center positive and others center negative (less common, at least around me)?

Is there any compelling reason, something that asks for one or the other for different devices? Couldn't they all be center positive as a matter of convention?

Is this like asking why not all cars drive on the left (right) side of the road? Or why not all countries use the metric system?


texts: Is there a switch to charge single batteries in a series array?

texts:
A couple of days ago when temperatures here reached 105 in the shade, my wind turbine’s permanent magnet generator was damaged.  The magnets were subjected to temperatures (180 degrees or more) such that voltage produced has dropped from thirteen or more to nine or so at the same turbine speed.  I have a deep-cycle battery array of four six volt batteries hooked (of course) in series-parallel.  I’ll build another generator (I was designing another turbine, anyway) but meanwhile I’m wondering if there is an electrical control device - relay and sensor - that I could use to charge one battery at a time, switching as each battery reaches full charge.

Obviously and with my generator capacity what it now is, I'd like to charge one six volt battery at a time.  Is that possible?


texts: How to connect Sonoff Minir2 to this wiring?

texts:
My ultimate goal here is to connect a Sonoff Minir2 to the existing switch in my wall. This video allowed me to identify the switch (Busch-Jaeger) (https://www.youtube.com/watch?v=rV6tC_0wF50) and showed which cables are live and neutrals.
Theoretically that should be enough information to connect the Sonoff Minir2, I assume.
However, in the video are only two cables. One live and one neutral. Now the switch in my wall has two live cables and two neutral cables though.
Can I just connect them to the Sonoff Minir2 in any order? As long as I don't switch live and neutral though, of course!
Then connect an extra two cables from the Sonoff Minir2 to the switch using the S1 and S2.


texts: Detect when a device has been connected to Vcc

texts:
I'm using an Arduino Uno to read input from an NES controller (a simple 8-bit shift register). This is working just fine, but I'd like to be able to detect when the controller is disconnected to shut down the I/O polling, otherwise the ATmega reads a bunch of nonsense input from the floating input pins.

My main problem is that I am extremely not an EE, so I'm not quite sure how to go about doing that. The controller has 5 pins: Vcc (5V), ground, strobe (latch the 8 parallel inputs), clock (shift the bits out), and a data output pin. It looks like there's a pretty substantial voltage drop at the ground pin on the controller when no buttons are being pressed.

Essentially, I just need to detect when the Vcc-to-ground circuit is broken, and set one of the Arduino's input pins high or low accordingly. Doesn't matter which logic level represents disconnected, as the code can be easily adapted either way.

I've got a few hundred resistors of various sizes, a box of assorted NPN, PNP, and JFET transistors, and only a cursory understanding of how to use them. :)


texts: Arduino, two buttons powering and digital inputs in the same time

texts:
I'm trying to determine if this circuit is going to work exactly as I think:

Expected behavior is:

When we press S1, arduino turns on and digitalRead(7) will give us HIGH value (INPUT_PULLUP is used) + digitalRead(8) will give us LOW value.
When we press S2, arduino turns on and digitalRead(8) will give us HIGH value (INPUT_PULLUP is used) + digitalRead(7) will give us LOW value.

Is this correct?

Okay, we found that is more or less working circuit, now another question:
How this would change if I power Arduino through it's RAW pin, using 12v battery? Do I still need to protect input pins using diodes and resistors or it's not necessary since internal voltage will always be the same 5v?

UDATE: I think I found another way of solving the problems with digital pin overvoltage:

Logic is pretty much the same, the only difference is that now digital inputs are pulled low using optocouplers, so the difference in the current between digital pin and the ground to which is connected - disappears, since it's the same ground as for Arduino.


texts: What is going on inside this nightlight circuit?

texts:
I've got a small nightlight in my hallway that has a photocell on top so it only turns on when it's sufficiently dark out. Sometimes the light will be off and a shadow will cover the nightlight as someone walks by triggering the light to turn on. After the shadow passes by and is no longer on the nightlight, the nightlight will stay on but only under certain lighting conditions such as a dawn, dusk or a particularly cloudy day.

This isn't a high-tech nightlight so I'm assuming that there's a simple electrical circuit that's causing the behavior. Can someone explain what that circuit is and how it works?

(I think this is probably something common and simple but if not, I can open the thing up and look inside for more details)


texts: I'm used to seeing circuit schematics with single/no grounds at all (drawn by teachers and some tutors) but now, I see circuits with multiple grounds. My question is, when drawing a particular schematic, what determines the number of grounds and where should they be placed?


texts:
I have here a Problem with an I2C bus configuration, that runs in a timeout after a certain time. The I2C slave is a fujikura ap4/ag4 pressure sensor and the master a STM32F4. I read continiously the pressure and after around 5-10min, a timeout error occures and the HAL_I2C_Master_Receive always returns a timeout error after that. The error occures in the stm32f4xx_hal_i2c.c because the following routine falls into a HAL_TIMEOUT

   /* Wait until ADDR flag is set */
  if(I2C_WaitOnMasterAddressFlagUntilTimeout(hi2c, I2C_FLAG_ADDR, Timeout, Tickstart) != HAL_OK)
  {
    if(hi2c->ErrorCode == HAL_I2C_ERROR_AF)
    {
      return HAL_ERROR;
    }
    else
    {
      return HAL_TIMEOUT;
    }
  }

Edit: What I noticed is, that the I2C3->CR1->STOP is set before the HAL_I2C_Master_Receive call when it returns an error. When I then clear this flag a few times while debugging, the I2C recovers and runs then again, until the next, same error occurs.


texts: highlighting multiple elements of same name in eagle

texts:
Is there a way that I can make eagle highlight only all components with the functionality I choose?

For example, In my circuit, I created a "staple" so I can use a standard staple as a jumper wire, and I figured out that Eagle names them U$xx where xx is a number.

If I type in show U$xx where xx is a number that matches the number in use (for example if I had a staple named U$1 and I typed in show U$1) then that staple highlights.

I can probably succeed if I typed in show U$1, show U$2, show U$3 and I keep going until I get to the highest number, but in my project I could change the number of staples (jumper wires) in my project and the numbering might be off, but they all start with U$. So I tried show U$* and I tried show U$[0..n] where n is the highest number possible and eagle tells me its not found.

Is there a way I can show all staples at once with one simple command? Let's assume their names start with U$.


texts: Is a mosfet considered as a transconductance amplifer?

texts: Is a mosfet considered as a transconductance amplifer because it converters input voltage into output current?


texts: Compare implementing a simple automation design on a MCU vs an FPGA/CPLD

texts: I have been working with MCU's since the 90's, and I've recently ventured into the FPGA scene with the Spartan6 series chips from Xilinx. Assuming a simple factory automation design with sensors and motors, and some intelligence to link everything up, on which type of device could I finish the design faster and easier, MCUs or FPGAs? Small or "obvious" points are also appreciated because I'm new to FGPA's in general.


texts: Mixed-Signal modular system grounding scheme

texts:
I'm attempting to create a sensitive, precise mixed signal system (more than 24bit) compose of a backplane and stacked modules on 2.54mm headers.It is multi-channel and channel's modules are well separated with independent supplies of their own.
The only common module is the DSP, therefore all separate GNDs of all modules will meet at a single point is the DSP's supply GND.

My questions are :

Please take a look and see if there is any problem with my wiring ( quick draft attached below ), both in DC and low-freq noise ( shared impedances in GND return paths ) and HF, spiked noise ( digital and analog return flows ) ?

Is there any advice/caution regarding making a system on backplane ?
The 2.54mm hdrs are good enough for 50-100MHz signal ? Any caution making connection through these tiny pins, especially with GND involved ?
Should I treat the BCKPLN as a board of wires and traces only, or make use of it's copper planes for some further benefits ?

Thanks.

Here is a quick draft of system wiring :


texts:
Is there a way to get reading from rotary encoder without microcotroller?
just simple circuit that count and increment, like op amp or 555 timer or logic gate . anything that u can help me .


texts:
I Am currently looking for battery suggestions for use in one of my projects. My projects current consumption (calculated) is

360mA for the main rotor 2.5A stall Link (my exact part RK370SD-4045)
400mA for the Mbed uC
tail motor ? unknown specs, N30 is the only part reference
3x servos Link unknown mA
sensor 100mA or less

Voltage has to be 7.2V to 12V

What I would like to know is what are the pros and cons of each battery? This link gives some great info but i want real world recommendations and things I should look out for and any other pertinent information when selecting my new battery.

Currently I have looked for batteries and have come to this conclusion, Lead Acid batteries are not a choice in this project, which leaves me with Li-ion batteries, Li-Po, Nimh, NiCd. The original battery was a 9.6V 650mAh Nimh battery and the helicopter had about 20 mins of flight time with the original equipment.


texts: building an unlock system with bluetooth and mobile phone using arduino

texts:
I want to trigger the completion (connecting) of a circuit.

I want to do this via bluetooth on mobile phone. Setup:

User turns mobile app on
User puts phone near bluetooth reciever connected to arduino
Phone's app has code sent over signal that is used to authenticate
Arduino sends signal to electronically open door

I use a mac. I'd like to develop this.

Type of Arduino to buy? Correct bluetooth receiver? Software needed for all of this?

thanks for your help, I'm mostly a CS guy


texts: Proper Arrow Directions for Off Page Connectors / Symbols...

texts:
Good day everyone,

As I understand it, there are two kinds of objects that can be used on a schematic to indicate that the Net to which they are attached is connected to a location elsewhere on the schematic (maybe the same or a different sheet).  The reason is to allow the flow of the schematic to be clear and / or to allow a signal path to be continued on another page.

I have heard / seen these objects referred to as off page connectors (or symbols), ports, etc.  I am guessing that they may (or may not?) have different names depending on whether or not the signal appears elsewhere on the same sheet.  In that case, I have often seen the Net line simply end, with a little alias or name at the dead end that can be found elsewhere on the same sheet.

The real question I have is this:  I am trying to understand the correct direction of the arrow to select for the off page (or on page for that matter) connector symbol.  I gather that, for logic signals, gate outputs and the like use the arrow direction arranged such that the outputs are pointing to some other gate's input.  That other gate input has a corresponding incoming arrow.  But what if there is a control voltage / current to be applied to an external load and there are two wires, a send and return.  I can imagine that there would be one arrow out (the outgoing driving current (conventional)) and one arrow point back in (the returning current (conventional)).  But, I wonder if both of these arrows should point outward (towards the load), since they work together to act as a 'data signal output' (and what if the output pair is an AC voltage?). In summary, what is a good, consistent, standard practice to assign directional arrows for on page / off page connector symbols?  Do I follow the conventional current, or the flow of data?  Or does it depend?  I know there are bidirectional arrows available.

This is my first question.  I do believe I searched thoroughly enough to be sure it is not a redundant question.

Thank you very much for reading!  Any advice will be very much appreciated!  Best,
Eric


texts: Ammeter ideal for testing, leaving on work bench for long periods

texts:
I am currently working on my first li-poly power supply, and I am testing Texas instruments BQ21040 PMIC.

The device has three charging phases that I need to monitor to do some troubleshooting.

I was using my Fluke branded digital multimeter to monitor charge current between the battery and output pin of the PMIC, but it wasn’t practical because the multimeter Kept powering down after a few minutes of runtime, and that halts the PMIC cycle, I believe.

I’m looking for an ammeter that is ideal to leave in a circuit for relatively long periods of time, something that could be left on your desk and you wouldn’t have to “baby-sit” it.

Rookie in the Electrical Engineering field so not sure of a the classification or specs to the ammeter I’m looking for. Any suggestions? Thanks!


texts: How does using double antennas (one with delay) and adding their output help the SNR?

texts:
This is a question our professor asked us to think about. Suppose that we have a communication system with no interference with no channel imperfection but Ergodic AWGN noise. We use two antennas with one slightly further away from the source. How does adding the output of two antennas help the SNR?
I tried analysing it in frequency domain but to be honest I'm lost and don't know how to approach it.


texts: What are some of the reliable color sensor circuit?

texts:
We want to detect four different colors:

Red
Blue
Green
Yellow

There are many different color sensor circuits using photodiode and LDR available in the internet. What are some of the reliable circuits which doesn't get affected by the ambient light also. The controller used is arduino.


texts: Why does the diode current waveform look like this in a full-wave rectifier?

texts: The oscilloscope trace below shows the output waveforms for the diode current (yellow) and the load voltage (blue) for a single phase full-wave uncontrolled bridge rectifier. The load attached to the rectifier was a resistive-capacitive load. I understand that there is a current spike every time that the capacitor charges up for every half cycle, however i do not understand why this spike alternates in polarity, isn't the spike always supposed to be positive?


texts: Are there FPGA chips that permit to update the programmable logic from the logic itself?

texts: For the research purpose I am interested are there FPGA chips that are capable to update the bytestream (the programmable logic) from the bytestream itself?


texts: What's the difference between DSUB25F and DSUB25M?

texts:
I want to simulate printer port in multisim.

But I found that printer port(25 pin) also have two choices,such as DSUB25F and DSUB25M.

What's the difference between them? I couldn't find anything in google.

Thank you~


texts:
I was reading about diodes and I know that they have a certain parasitic capacitance.
Now, according to Wikipedia,

  At low frequencies parasitic capacitance can usually be ignored, but
  in high frequency circuits it can be a major problem.

I have trouble understanding what exactly happens, so if you could come with some explanations that'd be great.

Is this because when it comes to capacitors, voltage lags behind, or is it something else?


texts: I'm looking at this question with answers in my book and I don't understand one part of it. It works out the input frequencies shown at the bottom. Can someone tell me how they are getting they input frequencies? Where are they coming from?


texts: D flip-flops, but no feedback loops: impossible?

texts:
Using JK or T flip-flops, it's easy to create a synchronous N-bit counter by cascading them as depicted here:

The above circuit has no feedback loops in it. I have run into a situation where I would prefer to use D flops, but I also want to avoid unnecessary loops because of wiring congestion. My intuition says doing both (using D flops and avoiding feedback loops) is impossible, but I can't really put my finger on why. Both types of flip-flops save 1 bit of state, right? Sticking a feedback loop in on top of the D flop feels like adding another piece of state, but the system as a whole doesn't store any extra data.

Am I thinking about loops incorrectly? What's different about the D flip-flop that makes it not work here? Last and most important, is it actually impossible to make a counter using only D flops and no feedback loops, or am I just too close to the problem to see it?

Edit to clarify my question: Both D and T flip-flops have some kind of internal feedback loop; I understand that. Both D and T flip-flops store one bit of information. What is different about the T flip-flop that allows it to be used in a counter without adding more feedback loops? Or, alternatively, what about the D flip flop makes it inadequate for this purpose when used alone?


texts: How to add simulating files on oregano simulator

texts:
I would like to start simulating electronics by using Oregano software on Linux Mint. From my experience, once installed oregano and gnucap
sudo apt-get install oregano
sudo apt-get install gnucap

The software works fine with the electronic components which already have a model installed by default. However, according with what follows here, for many electronic components I should have to download the PSpice model and put it into the specific folder, otherwise the following message of error appears when I try to simulate the circuit:
"/usr/share/oregano/models/LM339b.model:
No such file or directory
Too few or none analysis found"
As a first attempt, I tried to install and simulate a LM339a op amp, the model of which (available from here) is on my desktop. The line of code to write down on my terminal (after adding .model extension on the file name) should be
sudo cp -r /home/stefano/Desktop/LM339a.model /usr/share/oregano/models/

The previous message of error do not appear anymore, the software looks working but still the software doesn't provide any simulation as it seems to fall in something like a crash.
So I thought it may happen because of a wrong model, something which is not compatible with oregano. For this reason I tried with the LM358, which seems to be one of the most used op amps in the world. The problem with this is that there are many simulating files, as reported here, but the files have different sort of "strange" extensions, noone of them being a .model file. So now the question is:
which is the right file to download and copy on the "models" folder in order to simulate the LM358?


texts: Data transfer to Android USB Digital Audio device

texts:
Android 5.0 (API level 21) and above supports a subset of USB audio class 1 (UAC1) features:
https://source.android.com/devices/audio/usb.html

related links:
https://source.android.com/accessories/custom.html
http://developer.android.com/guide/topics/connectivity/usb/accessory.html
https://developer.android.com/guide/topics/connectivity/usb/index.html

Can a USB audio class 1 device interface with an associated Android application via AOA?

It seems that Android can handle only one accessory at a time, so I can't present a USB audio and an AOA custom accessory on the bus separately.


texts: P-MOSFET allowed some reverse current, L7805CV destroyed. Why?

texts:
I was experimenting with reverse voltage protection using a P-channel MOSFET. I hooked up an IRF9510PBF in the following configuration (diagram from Nick Gammon's site, will change if requested):

When I hooked up the 12 V power source backwards to see what would happen, the first thing I noticed was that the output voltage (labeled LOAD) was -1 V instead of 0 V. However, it had very little current capacity—I think it put around 1.4 µA through a 470 ohm resistor. Next, I hooked up the load, a L7805CV 5V regulator, to see what would happen. There was a smoothing capacitor across the outputs which I had forgotten about (100 nF), but I'm not sure if that was the problem. Nothing obvious happened, so I corrected the power polarity. The regulator started to smoke in less than two seconds. I cut the power, donned the respirator, added a heat sink, turned it back on. It ran very hot, and kept an LED lit for about an hour.

Is it correct to say that the MOSFET is mostly to blame? If all reverse polarity protection circuits are like this, I might as well not bother. Or is the fault that I may have connected the regulator while a capacitor across its input was partially charged with negative voltage? (In the real world, the load would be connected the whole time, and the capacitor would never have a chance to charge.)

The 5 V regulator is in a TO-220 package, and it was working fine until I subjected it to reverse voltage. But I thought it would take more than microamps to damage it.

This is the circuit, with reversed input voltage:

This is a photo, which may not be useful because it's too compact. The MOSFET is on he left, and the voltage regulator is on the right. The red and black wires represent the 12 V and ground connections—I had to remove the actual terminal, and shift some wires around so you can see what's going on:


texts:
I'd like to duple check from units of PID gains for the velocity of car.

This my equations for PI controller

V (m/s), kp (1/sec), ki(1/sec^2), kp' (radians/sec) , ki' (radians/sec^2) and kd (no unit)

I am right?

please help me

Thank in advince


texts:
I'm putting together a circuit board to power and dim 5 LED channels.

The average voltages on the channels are 12.3V, 11V, 11.4V, 7.8V, 6.6V, and max current is 1A.

So my current plan is:

12V Constant Voltage Power Supply input...
splits into three LM2940CT-12 LDOs, and two 7808 linear regulators.

So I should have more or less 3 x 12V and 2 x 8V signals.  Then I'll use a microcontroller with 5 x 5V PWM outputs to switch five line-level N-MOSFETs (eg. IRL520N), to dim the 12V and 8V signals before they reach the 5 LED channels.

I'm a noob at electronics, so there might be a better way. Looking for confirmation or suggestions on how to improve this design.

Thanks


texts:
I need to solve exercise 57. I need to determine the voltage between points A and B in diagrams (a) and (b).

What I think so far:

The voltage on 10 ohm resistor is = 0.1A * 10Ω = 1V
The current on 20 ohm resistor will probably be 0.1A too (I think, I'm not sure). In this case its voltage is 2V (0.1A * 20Ω)
UAB = Upower-Ur1-Ur2 = 4.5V-2V-1V = 1.5 V

Is it correct?

Thanks for your help.


texts: Circuit corresponding to positively skewed bode plot

texts:
I have the following bode plot for an unknown circuit

It seems like there's underdamping going on, but otherwise I'm not really sure what sort of circuit would produce a plot like this, other than that I'm sure that all the elements in it are linear.


texts: Controlling color (and brightness) of RGB LED strip using one potentiometer

texts: I'm trying to find a circuit that can manually adjust the color of a RGB led strip with one potentiometer.  Ideally it would be a dual potentiometer to control brightness as well as color. But not necessary. I understand I may need a microcontroller to do this, but I am too much of a novice to figure it out on my own.


texts:
I'm trying to perform communication with a Motorola MPC5606B microcontroller using a cable that I already had previously. Using this cable will make things easier in my lab because everyone has one the same. But I have a concern: there is a diode 1N4007 in line with Vcc.

simulate this circuit – Schematic created using CircuitLab

So, because of the diode on the VCC line, the I/O voltage can be greater than that specified on the datasheet. The datasheet specification is given in the figure below.

So, my concern is: if the voltage on the I/O pin is 0.3V greater than Vcc, but below 6V, can it damage the I/O pin of the microcontroller?


texts: Low or High ESR for LDO for a wireless board?

texts:
I'm designing a board powered by a LiPo battery and the AP2114H LDO. At the battery side, I chose to use a 100nF ceramic and a 220uF tantalum. But I do not understand what are the considerations for choosing a low-ESR (and cheaper) tantalum vs. a high-ESR one. For example AVX TPS series vs. AVX TLN series.

Which tantalum capacitor would fit better, low-ESR (150 mOhms) or High-ESR (1300)?

The circuit itself is a wireless module, using the ESP8266.


texts: How do I re-attach this FFC cable to this connector?

texts:
While trying to detach the cable, I pushed out the black part, which came out from the opposite side of where the cable enters the connector.

The cable was previously tightly clipped in place and came loose after the black part came out.

How do I re-attach the cable, or is the connector permanently broken?

Is there a name for this particular connector? There seems to be a few names, like zif, etc but I'm pretty sure mine isn't zif.


texts: Do short circuits between transformer windings cause noticeable change in EMF?

texts:
I am looking into developing a sensor system to be placed within a transformer. This sensor system in theory, should be able to detect any unprecedented change in EMF within the transformer enclosure.

I understand the EMF of a coil of wire is F= Turns*current in the windings.

In theory, a short within the windings would cause, a change in EMF, because the number of turns have changed.

Is this the case?

And would a small circuit being exposed to such high magnetic fields potentially damage the circuit. For the purposes of this question, let us assume the sensor is a small embedded system that is powered by a low-voltage DC battery.


texts: Using a low-voltage switch in a high voltage circuit

texts:
I have an application that requires switching a circuit between the following two configurations. Circuit Lab is infuriating as it does not allow you to draw diagonal wires, so I used arrows instead. They are not connected in the middle.

simulate this circuit – Schematic created using CircuitLab

I have thought about using a DPDT NO NO switch to swap between the states but the switch is only rated for 12 volts dc, and I want my circuit to be operable up to 170 volts.

Because the resistors will absorb almost 100% of the voltage drop (assuming the resistance of the switch is negligible), I am assuming that I will not have power or current-rated problems considering that the whole setup will be shipped with a 1/4W power rating. The problem I will likely encounter has to do with potential breakdown of the switch from arcing and the like.

I would not hesitate to insert a SPST switch in series with two large resistors at any voltage, as the voltage drop across it would be almost nothing. However, in my setup the DPDT switch would have the full 170v potential across the two poles. If I use a small switch in this configuration, would I be safe or would my switch arc/breakdown across the poles?


texts: I'm reading a datasheet for an accelerometer (specifically this) and it lists the max supply current as 290 uA. Does this mean that the power supply I use should never output more than 290 uA? Or does this just mean the device only consumes 290 uA max? In standby mode, the max supply current decreases. Does this mean I have to dynamically reduce the output current from the power supply?


texts: Using a pulse-width modulated signal to possibly reverse polarity

texts:
I'm trying to help an artist control a simple DC motor using a single signal. The signal is a digital output, 0/5V, and the motor runs with max 36V. The motor needs to run forwards and backwards. There is only 1 digital output available per motor.

I know how to generate a PWM signal, and wire it up to a transistor (with resistor at the base) so that the motor spins slowly or quickly, that much is working. We have a simple circuit for motor speed in one direction.

Also thanks to this site I just learned about H-bridges and found a few good pages on using 4 transistors to switch a motor's polarity.

My thought was to have the output signal be pulse width modulated 0% = full reverse, to 35% = slow reverse, and 65% = slow forward, to 100% = full forward.

To make that control the motor, I think about splitting the signal into two isolated parts. I "smooth" one part and use it as a "direction control" signal, low=reverse, high=forward. The other original PWM signal just modulates the power, for speed control.

I can't get it working in my circuit simulator. First problem is that my "smoother" is a filtered rectifier, and it always produces the same output voltage regardless of the duty cycle, which makes sense, because the diode bridge just converts everything to the same voltage. The second problem I have is how to make the "low" parts of the duty cycle make the motor run "fast" when it is in reverse- pretty sure I can fix that with a NOT gate and another transistor, but it feels like there must be a more elegant way. The fewer parts in this design, the better.

(Main problem is that I'm in over my head. Haven't built any circuits in 20+ years.)

The question is- how would you make this work, using a 36V power supply and some components to convert a 0-100% 5V PWM signal into a -36V to +36V PWM power source?

FYI, We do have the option of just buying a second microcontroller, which would give us more output pins, which would let us use one pin for a "forward" signal, and another for "reverse." It's just frustrating me that I can't make the single-signal idea work.


texts: Transfer power effectively from one coil to another through air

texts:
I want to build my own wooden alarm clock.

I want the surface to be smooth without any connectors anywhere. My idea is to place one coil beneath the alarm clock, and another pickup coil inside. I suppose that I need to maximize the area.

What kind of power can I hope to get through?
What is the optimal frequency? (is 50 Hz ok)
Do I need to worry about radio polution?
Will an unconnected iron core help?
What is best - many or few windings?

Please also tell me, if you know of other reasons why this would not work.


texts: BLE (blue tooth low energy) : what is the difference between encryption and whitening regarding to packets?

texts:
In BLE, what is the difference between encrypted packets and whitened packets?
Is the whole packet encrypt/whitened or just the payload?

I know that whitening is used to "whiten" the signal so there is less 0000000.... and 1111....
I know that encryption is used to "encrypt" the signal with a key (sym or asym), so the packet (or just payload?) is not readable for non key-holders.

I'm testing a low lever driver for BLE stack, and I want to know what to expect while testing encryption and whitening.


texts: What is this jelly like substance on electromagnetic shield of a LTE Modem?

texts:
I took apart a Huawei E3372 LTE Modem, and this is what I saw. A jelly like substance on the electromagnetic shield.

It is very soft and a bit sticky. I guess it is there to dissipate the heat from the modem, since it couple well to the back enclosure of the modem.

What is this substance and what is the function?


texts: Question related to two closely separated signals that need to be analyzed by a spectrum analyzer

texts:
Question

  The settings of a spectrum analyzer are given as following:

  Center Frequency = 1.89 GHz, RBW = 10 kHz, VBW = 10 kHz and Span = 50MHz.
  The Reference Level is set to -20 dBm and detector mode is Positive Peak.
  The RBW selectivity is \$1:15\$ for \$RBW_{-3 dB}\$ : \$RBW_{-60 dB}\$.

  If we are studying a CW signal of 1890 MHz with -23 dBm output power, then

  a) How close to your studied signal may a signal of the same amplitude be
  and still be measurable? Explain the conditions for close-in signals to be resolved.

  b) How close-in signals with power level 50 dB below your studied signal can you detect?

My Attempt

Is my reasoning making sense to you?

a) "Thumb rule" (I guess?) for equally powered CW Carriers, they should be at least \$RBW_{-3 dB}\$ far apart in order to resolve and measure them.

b) For unequal powered signals CW Carriers (have power difference of 50 dBc), they should be at least \$RBW_{-50 dB}\$ far apart in order to resolve and measure them.


texts:
Im using STM32F411CE. It has 2 kinds of counters, one kind has 16 bit counter resolution while the other has 32 bit resolution. What exactly is the difference?
I assume its going to be better to take the one with larger resolution.

EDIT: So what exactly is going to be advantage of bigger resolution, am I going to be able to generate more precise PWMs?


texts:
I don't understand the way ST specifies their current sense pin in the VNH7070 H-bridge motor driver, see the datasheet below.

How do I know what the current Isense will be? Why does the voltage Vsense remain the same for different currents, assuming Rsense will remain the same.

Why is the current Iout only specified for 0.05 to 5.5A, while the chip can deliver 15A?


texts: Relation between Voltage & frequency in DVS

texts:
As per Wiki - "In DVS,  Overvolting is done in order to increase computer performance"

How Overvolting will increase performance??

Also, it says " By applying a higher voltage to the devices in a circuit, the capacitances are charged and discharged more quickly, resulting in faster operation of the circuit and allowing for higher frequency operation."

Aren't the above 2 statements contradiction with for eg DDR2/3/4 where we are decreasing voltage to decrease rise time & further increase performance??

What am I missing!!!


texts:
Series resonant circuit with parallel capacitor:

What is effect of that parallel capacitor (C2) on the circuit? And what happens if we remove this capacitor?


texts: How are ESCs (for BLDC motors) different from Texas Instruments sensorless Instaspin kits?

texts:
I have never used an ESC before but are they current (torque controlled) or speed controlled? If we vary the load suddenly ,will it stop or it can identify the rotor position and maintain the speed ?

Texas Instruments sensorless Instaspin kit: DRV8312 EVM


texts: What can I do to avoid impedance discontinuity when high-speed signal bifurcates on PCB?

texts:
As mentioned before, I want to supply two PCBs with same-frequency clock(as high as 10GHz).But now there is only one pair of differential clock, while both of the PCBs need one.

So I am thinking of using an extra PCB, whose task is to distribute one clock into two. However, this involves a bifurcation for the high-frequency clock, inevitably causing impedance discontinuity.Is there any better way to deal with this?


texts: Analyze protocol used for Futaba VFD display, 3 data pins

texts:
I take apart a Samsung SMT-C7140 HD Unit (made obsolete by cable company, a shame) and found a nice display that I could probably reuse. It is a Futaba GL07-00006A (13-BT-246GINK). I tried to find the service manual of the Samsung unit, tried to find a datasheet of the Futaba display, however no luck.

So I started to analyse the connections of the front-panel/display and figured out that It could be possible to reuse the whole front-panel, inverter is also on the panel. The Futaba has no external driver (no chip underneath the display or on the motherboard) so I thought it might be a Chip on Glass (COG) display (because of less pins on the display), I think I am right however they call it Chip IN Glass (CIG). After figured out the pinouts (see pictures below this question), solder a header and connect an Logic Analyzer to it.

The 4 data pins on the Futaba are directly available on the flat cable connector. There are a few microcontrollers on the board and a main processor. After reading the pins with analyzer, I see something like this:

You can download the captures in a zip, did several sessions, available in Saleae Logic file format, PulseView and in VCD file format.

Tried several standard protocols and I2C gave some result on CH0 and CH1 but that seems a bit weird because of the extra two data channels (some clock or enable sequences). Also tried SPI (could be possible because of 4 data lines) however many errors or no result.

Question:

Does anybody recognize the patterns or protocol used to steer this display? Does anyone know what kind of driver is inside this display?

Some pictures I made:

(image removed, see update below)

Update 04042020 (<-funny date!)

It would be nice that there was a tool to record and playback the (boot-)sequence to be sure that everything is properly connected after changes to configuration are made. Something like an audio wave player, a TTL 'wave' player. Without it is really hard to do because a mistake is easily made. When it isn't working, it could be the used protocol or the connections. It can make you quite insecure because you don't know exactly how it must perform exactly.

I have tried to hook a microcontroller (after cover the datalines on the ribbon cable) to the datalines (there are only 3 and not 4, one of them seems to be power +5V - see also updated 'schematic' below) and share ground to try some software that implement similar devices and their protocol.

Did not find any official Futaba examples, elsewhere or on the outdated looking website of Futaba itself. After register and login there are an impressive ammount of datasheets however no way to search for characteristics. Also in the datasheets there are no examples, just specifications, lack of details "how to do it" is enormous.

Came across this Noritake source and after browse their catalog of products. They provide some libraries for AVR and tried most of them. The code is..... not a beauty, sense of taste I quess. Also found "Newhaven display" and allot of other similar stuff such as Adafruit. The all do similar techniques, copy schematics and such. The most interesting I found was a datasheet of PrinceTon technology (PT6314), that looks very similar however different ONLY to the Futaba datasheet (and they provide examples in their datasheet):

[

The major difference is difference in rising and falling edge. However, I still don't know if this is the correct protocol to use. So yeah, they made it really hard to be able to reuse some stuff.

I tried a lot of things right now to safe the display will end up the landfill however have some doubts I will find the right solution. So for now, I will stop this journey (unless there is a real solution) and leave the information here maybe for future use. In hope that manufactures start to label (connections of or privide a datasheet (with examples or code) of) non-critical components of their short-life products to be able to reuse instead of throwing away.

Updated image/schematic:


texts:
For my exam I need to calculate the apparent power, active power and reactive power.

I know I get the active power from the real part and reactive power from imaginary part of the apparent power. However, I can't find any formulas for my specific problem.

I have

\$ U = 82.58 e^{j31.89°} \$ and \$ I = 1.65 e^{j31.89°} \$

The formula I found is

\$ S = \frac{1}{2} UI^* \$

But it starts with the problem that I don't know how to get from for example \$68e^{j30°}\$ to something like \$68.19 - j42.45\$

Used Euler.
But know I don't get the correct solution.
I have \$S= 0.5* 82.58 e^{j31.89°} 1.65 e^{j31.89°}\$
That would be \$S=68.13cos(63.78)+j68.13sin(63.78)\$

Tried to conjugate "I" like that: \$I=1.65 e^{-j31.89°}\$
But then \$\Phi = 0\$

But the solution is \$S=68.19 - j42.45\$


texts:
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity ASM is
port(clk, rst, A, B: in std_logic;
    Z:buffer std_logic_vector(1 downto 0));
end ASM;

architecture asm1 of ASM is
type t_state is(T0,T1,T2,T3);
signal current_state, next_state:t_state;

begin
memory:process(clk,rst)
begin
    if(rst='1')then
        current_state<=T0;
    elsif(clk'event and clk='1') then
        current_state<=next_state;
    end if;
end process;

next_state_decoder:process(current_state)
begin
case current_state is
    when T0=>if(A='1' and B='0')then
                next_state<=T1;
                else
                next_state<=T0;
                end if;

    when T1=>if(A='1'and B='1')then
                next_state<=T2;
                else
                next_state<=T3;
                end if;

    when T2=> next_state<=T0;

    when T3=> next_state<=T0;

    when others=> NULL;
end case;
end process;

output_decoder:process(clk,A,B,Z)
begin
if (clk'event and clk='1')then
case(current_state) is
    when T0=> if(A='1'and B='0')then
                Z<="00";
                end if;

    when T1=> if(A='1'and B='1')then
                Z<="10";
                else
                Z<="11";
                end if;

    when T2=> Z<="10";

    when T3=> Z<="11";

end case;
end if;
end process;
end asm1;

Hi, i'm trying to display the output waveform in modelsim, but with this code, I wasn't able to get the output of Z, the output of Z shows nothing.

Testbench code:

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity ASM_tb is
end ASM_tb;

architecture behave of ASM_tb is
component ASM is
port(clk, rst, A, B: in std_logic;
    Z:buffer std_logic_vector(1 downto 0));
end component;

signal clk: std_logic :='0';
signal rst : std_logic;
signal A,B: std_logic;
signal Z: std_logic_vector(1 downto 0);
constant clk_period: time := 40ns;

begin
uut: ASM port map (clk,rst,A,B);

clk_process:process
begin
clk<='0';
wait for clk_period/2;
clk<='1';
wait for clk_period/2;
end process;

-- Stimulus process
stimulus: process
begin
A<='0';
B<='0';
wait for 20 ns;
A<='0';
B<='1';
wait for 20 ns;
A<='1';
B<='0';
wait for 20 ns;
A<='1';
B<='1';
wait for 20 ns;
A<='1';
B<='1';
wait for 20 ns;
A<='1';
B<='0';
wait for 20 ns;
end process;

end behave;


texts: Why do my all Atmega328P chips stop responding suddenly in a 12v circuit with Zener diode?

texts:
I have noticed this strange thing where my atmega328p stops working and when checked through Arduino IDE or AvrdudeSS or ProgISP, they show programmer not in sync, rc=-1 initialization error (while the same circuit recognizes a new chip).

EDIT3: Zener removed form schematic as the problem exists even without the zener.

My circuit has a 12volt input coming from an adapter, then to 7805 and 7805's 5v output to my atmega chip. The circuit worked all fine until 7805 was moved a bit by jerk and all becomes hell, atmega stops. Is it permanent damage? I am unable to understand what is it and my money is wasted on buying new chips and demoralizing me to continue.

EDIT: I must also mention that one of my chips died in the same way while I just had an led tested with the chip's 5volts. All I noticed is a "jerk" to 7805 did it (switched-off the led and then the chip stopped responding to anything)

EDIT2 - Is it possible that fuses go wrong if chip resets due to jerk on voltage regulator or anything similar? I know it sounds silly. I always burn bootloader on my new chips using usbasp and Arduino IDE 1.0.1 and then set fuses using AVRDUDESS default fuses for Arduino Uno (L 0xFF H 0xDE E 0xFD, after which blink program blinks at normal rate).


texts:
Below schematic is a voltage regulator circuit minus the compensations/filters parts (capacitors etc):

simulate this circuit – Schematic created using CircuitLab

The amount of current the op amp is sinking is not more than ~2.6 mA but for some unknown reason the op amp is getting a little warm (~42-45°C).

What causing the op amp to heat up?

Datasheets:

MC33079
2SD1047
TIP122
LM317


texts: Beginner: Inductors in Series and Parallel HELP

texts:
simulate this circuit – Schematic created using CircuitLab

I am looking for help with what is probably a very basic question but I am new to electronics. The question I have is on a circuit and how to find various voltages, current, and resistance involving inductors.

In the question the circuit is using AC 120 V / 60 Hz and the first inductor (L1) is 100 mh it the splits in two with inductors L2 200 mh and L3 300 mh in series and they are parallel to L4 which is 400 mh and then it comes together back to the power source.

This is what I believe I have solved thus far:

The L Total is 322.222 mh
XLT is 121.475 Ohms
IT (Current Total) is 0.987858 A or 987.858 mA

I am asked then to figure out VL1, VL2, VL3, VL4, and IL2

VL1 I found by taking IT and multiplying it by XL1 and I got 37.241 V

I also got VL234 and got 82.759 V.

I just don't know how to split this up to get the individual voltages for VL2, VL3, and VL4.

Hope someone can help! Thanks.


texts:
The South Africa regulations states that the maximum power to be transmitted is 4W EIRP. What does this EIRP mean here?

Secondly when using the Friis equation:
Power received(dBm) = Power transmitted + Gain of transmitter - Cable loss - Free space path loss

I have read that the Power EIRP(dBm) = Power transmitted + Gain of transmitter - Cable loss.

Therefore the Friis becomes:
Power received(dBm) = Power EIRP - Free space path loss

And hence the Power EIRP(dBm) is 36.02 dBm (4W EIRP)

Therefore the Friis becomes:
Power received(dBm) = 36.02 - Free space path loss

Is this correct?


texts: Do Ebers-Moll model cover all working modes of BJTs?

texts:
I mean the normal working modes (cutoff, forward/reverse active, saturation).
Or an other form of the question: Do Ebers-Moll cover the whole working domain of BJT (in potential and current values)?


texts:
When choosing the L/C ratio in this reference text states that you need to
choose 1.5pf for one meter wavelength. Why is that?
How that leads to have higher gain? How that leads to have a
higher dynamic resistance?

  Basic radio theory, circuits and calculations

What is the connection between these two?

--thanks in advance--


texts: I know this is kind of a noob question. I am trying to establish a wireless communication between two 8051 microcontrollers using a 433 MHz RF module. But since 433 MHz is a quite noisy frequency, the receiver immediately starts collecting the garbage around. In this case, would implementing a software filter do the job to eliminate the garbage data or is my data getting completely disturbed on the way? Thanks in advance.


texts:
I have a DC LVDT here with a built in signal conditioner:
http://www.te.com/usa-en/product-CAT-LVDT0004.html

I have a weak background in electronics, so I really have no clue who I'm supposed to extract signals from this sensor. Ideally I would want it hooked up with an arduino. Anyways, three wires:

Red: +VCC (Loop supply Input)
Black: -LOW (Loop supply Return)
Green: Case Ground

Any help on setting this up would be much appreciated!


texts: Do these two memory register diagrams look correct?

texts: So to start this off I have used J-K flip flops instead of D flip flops due to the equipment that I'll be using (Logic Tutor LT345 Mk2). The first diagram I am confident is correct but the 2nd diagram being the Parallel to Parallel memory register I am unsure of. Instead of connecting Q to J, I had Q on its own as the output while connecting switched to each J input, looking back at the 2nd diagram I've taken out the input labeled Parallel Data in because I'm confident the bottom four switches will be parallel in and the above outputs being parallel out. I would appreciate anyone's input. Updated image below.


texts:
I need a replacement part for the potentiometer depicted below, dimensions are approx. 16x13.5 mm.
The bottom reads "B100K" and "SEL" and the resistance between the two outermost contacts is a little less than 100k, but a quick Google search didn't come up with a definite match (this particular model has a small inside thread to connect to the radio dial). The radio was built around 2012, if it helps.


texts: What is the fan connector on a PC motherboard?

texts:
Typically it is a three bare pin polarized connector, with power, ground and tacho connections. However, I am having difficulty finding it as a part. What is it called?

This is what I am trying to connect to


texts:
I am interested to use a RGB LED from Würth Elektronik. The schematic from the datasheet shows an extra diode across the green and the blue led. What is the propose of those diodes?
Link to datasheet: https://www.we-online.de/katalog/datasheet/150080M153000.pdf


texts: Can anyone identify this tiny 2.4/5.8GHz antenna connector?

texts: I'm looking to add a pigtail and larger antenna to small wireless video receiver. It came with a removable antenna with a connector I don't recognize. Sorry for the blurry pictures. If they're not helpful I can try again. It's a push on, and the center of it has the white plastic bit I've seen on RP-TNC connectors. The numbers on the tape in the images are centimeters.


texts: USB Type C Power Delivery with STUSB4500, making the device compatible to USB 2.0/3.0 using a USB A to USB C cable

texts:
for my application, I decided to use USB Type C Power Delivery in combination with the STUSB4500 (Datasheet: https://www.st.com/resource/en/datasheet/stusb4500.pdf) sink controller that helps to negotiate a contract with the power source more or less by itself.

Now my application (referred to below as 'device') draws about 1.5 A during power up, roughly 800 mA during regular operation, and 1.5 A worst case. It uses an STM32F0 microcontroller (referred to below as 'microcontroller') to exchange data between the microcontroller and the computer using its virtual com port (D+ and D- used, 12 MBit/s USB 1.0 full speed specification) with the computer. The device is either used

offline. Only running on power delivered by USB
or online, talking to the computer using the microcontroller for settings and firmware updates via DFU mode

Hooking up the device to a computer with native USB Type C support (MacBook Pro, the one with butterfly keyboard and USB C) is no big deal. It works fine as a PD contract is correctly negotiated.
But now I hope to make it work on older computers too that only have USB 2.0/3.0 (like my MacBook Air 2013) where it is connected via a USB A to USB C cable (like this one here: https://www.amazon.de/AmazonBasics-USB-Kabel-Meter-Schwarz/dp/B01GGKYKQM). I know the port of my MacBook is capable of charging my iPhone and iPad at 2100mA, however it is apparently not able to talk to STUSB4500. As a result, as the application wants to have 1.5A on startup, it doesn't power up at all.

I came up with one not optimal solution and would like to ask you about what a better solution could be:

My solution so far would use the PDO2 and PDO3 pins of the STUSB4500 to determine the case that no contract is negotiated (that seems to be the case when it is connected to an USB 2.0/3.0 port) and uses their High-Z state, according to configuration 2, to keep transistors off, that switch on the high current part which is actually responsible for drawing up to 1.5 A. This will make the USB 2.0/3.0 computer successfully recognize the device. And then, by negotiating more power with the computer after the microcontroller is detected, it can either turn on the high current part or keep it turned off.
This solution is obviously flawed, because when using the device offline using a plain USB A connector charger and an USB A to USB Type C cable it wouldn't turn on at all, as the charger will never talk to the microcontroller.

So what would you do to make a high power device using USB Type C power delivery compatible to an 'old' USB A only computer AND a 'plain' USB A charger?

Any help is greatly appreciated.

Thank you, stay safe and cheers.


texts: Why is there so much overshoot in my LED circuit and how do I prevent it?

texts:
I'm trying to PWM a 5 meter RGB LED strip with a microcontroller. With this setup:

simulate this circuit – Schematic created using CircuitLab

I have built it on a breadboard and probed the drain with my (new) scope and saw this huge overshoot:

Why doesn't the diode catch that spike? I though an 1N4148 would be fast enough.
The power supply is a 12V 6A switching power supply from eBay. Is that why the voltage drop as low as about 8V?

Here is the gate voltage:

The high frequency spikes are from the 12V rail it seems, here how the 12V supply rail looks like:

I realize that breadboards are crap for signal integrity especially since I have used crappy long jumper wires but I had never guessed it would be this bad.

So why doesn't the diode catch those spikes ? And how can I reduce them?
Also, is this power supply a total crap?

EDIT:

I have placed a couple of caps to decouple the power supply, there is still an overshoot:

I've added a 100nF ceramic cap across D4 and the overshoot is totally gone:

It looks good now, but notice the 2nd channel (in yellow). That's the power supply (which is a lot cleaner with the decoupling caps).
Now another question comes in mind:

Why is the Drain voltage only about 6v when the leds are off ?


texts:
I have to ask and understand it once and for all because I encountered a few opinions about this subject:
When I'm designing FPGA with Verilog or VHDL there is any meaning to:
Verilog ->  initial block
VHDL    ->  `:=`

in the signal declaration or does the FPGA synthesizer ignore these code parts completely?
For example, if I want the register "blabla" in startup to have the value 0101, is this the correct code:
Verilog ->
reg [3:0] blabla;
initial blabla := 4'b0101;

VHDL ->
signal blabla std_logic_vector(3 downto 0) := "0101";

If I want to initialize a register what is the right way to do it? Inside process / always block under the reset logic?
What ifI don't want to reset the value of the register but I do want to initialize the register?


texts:
Hi everyone! This is the question related to thevenin theorem. I have found Rth by making 6kohm open but I'm having some difficulties finding Vth for this  circuit.Can someone please guide me?
Va is 6V.


texts: DIN rail enclosure for a Arduino + Ethernet shield

texts:
I am looking for a way to put a Arduino with an Ethernet shield inside a DIN rail enclosure while exposing the RJ45 and a few screw terminals.

Bare min: 55mm Width, 75mm length, 30mm height.
Looks similar this http://arduino.cc/en/uploads/Guide/ArduinoWithEthernetShield.jpg

Parts list:

http://www.sparkfun.com/commerce/product_info.php?products_id=9026 sitting on top of
http://www.sparkfun.com/commerce/product_info.php?products_id=666

The problem we are having is how to expose the RJ45 connector.

We were thinking of finding an enclosure that supports a RJ45 Keystone and running wires from the board to the exposed terminals but we haven't found anything like that yet.

We where also thinking about getting the two boards redesigned in to a single board that fits a existing enclosure. But that would cost 1000s of dolors. Or at lest thats what I been quoted.

I been searching and phoning people for about a week without finding an answer. I'm  looking for suggestions, hints, wild guess, anything?


texts: Is there a reason GaN chargers stop at 65W?

texts: During the last year or so we have seen commercial release of USB chargers utilizing GaN technology. For some reason it seems no products go higher than 65W. The Navitas reference platform was 65W, Delta released a 65W under the Innergie brand -- but nothing higher. Is there a technology reason for this? USB C goes up to 100W and 87W is reasonably popular because Apple shipped some of their MacBooks with such and so it's easier to market those as replacement.


texts: Why P and N channel MOSFET is quite hot during braking of 3PH BLDC motor?

texts:
IRF4905 datasheetIRF 3205 Datasheeet

I am working on a 24-volt BLDC 3ph drive application.

I have made this design with a basic understanding of p and n channel MOSFET.

In this design, MOSFET gate pulse is in voltage range of 18-20 volt.

I am quite confused about choosing the correct value gate resistor. I found that it must be within 20-50 ohm. I applied many combinations but still, the problem lies the same as the previous one.

I also found that maybe the dead band is not quite enough that will make MOSFET hotter so I changed it accordingly. From 1us to 3.2us. But still no change in temperature.

Please note that the gate pulse is coming from the Allegro based BLDC driver A4963. I am also attaching schematic of it.

What can I do to reduce the heating?

N channel: IRF3205
P channel: IRF4905
Driver asic A4963 Allegro


texts: How does a layman interface with a system on a chip?

texts: I'm looking to build an incredibly simple robot that I control via bluetooth. I've identified the CC2540 from TI which will theoretically allow me to do this. It sounds perfect, it's like 5 bucks. Alas, I have no clue how to integrate this chip (or any SoC generally) into a larger system. It's pins are  much too small for a breadboard (duh)! I can't seem to find any hints online as to how an average Joe or Jane can utilize arbitrary SoCs to build cool things. Printed circuit boards, sure, but I'm not Bell Labs over here. Any resources would be welcome!


texts: 12V Low battery indicator that has minimal power draw

texts: I'm wanting to make a simple low battery indicator for 12V SLA battery - just an LED that lights when the voltage gets below a certain level. What sort of power would a circuit like this http://www.electroschematics.com/9010/12v-lead-acid-battery-low-voltage-indicator/ draw from the battery (when the battery is charged)? Is it worth considering a different circuit that uses less power?


texts: What keeps voltage/current/power from flowing into "branch two" from the "Vout" node in the below drawing?

texts:
I need Vin to go into one of two branches and then continue to Vout, the boxes represent DC-DC converter, one at 20V and another at 15V.
What keeps voltage from going through Branch 1 into Vout node and then into branch 2.
Obviously in the picture it looks like the boxes don't have a ground connection but in reality the boxes have ground connections as can be seen in the picture below

So what keeps Vout from entering branch 2?
Should I instead flip the design to look like the below picture where the switch is on the left side of the branches?


texts: Where can I find the datasheet for an DGL-0401YG-4EH LCD display

texts:
I recently bought a "goodie bag" or whatever it is called with a lot of different displays in the bag. I figured it could be useful someday or just to play around with. However it seems that the datasheet that was supplied didn't cover all the displays.

All I got was this: http://www.kemo-electronic.de/datasheets/s043.pdf

The component I have though seems to be a DGL-0401YG-4EH

Now I don't know how to actually get anything on that thing... so my questions is.

Is there a generic way to handle LCD displays or do you need a specific datasheet for each one?
If it is generic then where do I find a good place to start learning how to use it?
If not then where can I find the specific datasheet?


texts: Changing LED intensity by changing voltage

texts:
I learned in high school, that the I-V characteristics of a diode is far from linear. Until some voltage there is no current, then quite suddenly it jumps to being kind of linear, I think.

I have seen these LED strips, for instance on ebay, almost all of them are 12V. They come with some kind of power supply where one can change the intensity. For simplicity I imagine a 12V system on the primary/input side, e.g. a car, so I don't have to worry about AC curves when drawing below. My friend called it changing the voltage, when changing the intensity

I suspect that if the voltage is actually reduced the current through the diodes will suddenly jump from something (don't know how much) to nothing, according to what I learned in highschool. Is this correct? By reducing the DC voltage, I mean lowering the constant line V = 12V to e.g. V = 3V.

Therefore I imagine that what actually happens is that the voltage is 12V, but it is not constant. I goes 25ms at 12V and then 75ms at 0V. However, our eyes are not able to pick up that it turns on and off that fast, so it simply seems like reduced intensity. Whenever it is on, it is at 12V, and it draws the current it is designed for, and emits light, the at the voltage/current it was designed for.

For many purposes the discrete 0V or 12V versus the constant 3V will mean the same. E.g. a light bulb. Also when calculating energy usage it is the same.

However for the above mentioned reasons, I imagine that the constant 3V will not work for LED strips.

Am I right? Please enlighten me :)


texts: low resistance material used for sensing

texts:
I'm researching conductive fabric with a surface resistivity <0.5Ω/m2 (unstretched).

I've used a voltage divider setup to connect with an ADC pin of microcontroller (ATMega/Arduino board).

This setup works, but the fabric gets hot to the touch.
I suspect this is due to the low resistance and too much current going through. Is this correct? Are there other possibilities for this occurrence?


texts: Fine tuning PID controller for non-linear closed-loop system

texts:
I am having trouble getting my PID controller to be accurate over a range of values. My goal is to input a duty cycle for a PWM wave, which controls the speed of a fan rotor. The range of possible speeds should be 300RPM to 2700RPM.

Currently the PID controller is achieving accurate speeds when 800 to 1600 RPM is requested, but below those speeds the output is too high, and above those speeds the output is too low. I think this may be because the relationship between duty cycle and rotor speed is not entirely linear.

Here is our current PID equation:
duty_cycle = [ speedset + control + 735] / 4300
Speedset is the requested speed, control is the PID control variable, and the constants are from the equation that we found to be mostly accurate for linking duty cycle with output speed (it is however a linear equation, and was not entirely accurate for extremely low and high data points).

The control variable is: control = 0.104*error + 0.104*previous_error + 0.13*next_error

This is my first time working with PID, so please correct me on anything I am doing wrong. Does anyone have any advice for how I might improve the accuracy of the system at very low and very high speeds?


texts:
I need to run approximately 25 feet (8m) of cabling up to a project box containing an array of ultrasonic sensors. (note, I was not in charge of the design of this project, if it had been up to be I'd have gone with an array of I2C sensors and just used a single bus, but it's beyond that point now, and I'm just responsible for helping them run the cable). The sensors are low-voltage (5V), and of negligible current consumption (perhaps 100mA total), and the cable will be stored indoors, and will be stationary once installed.

I'm having trouble finding a way to source/buy some kind of cable that will have enough conductors (for a reasonable cost, ie. sub $250). I'll need 30 conductors total. None of the common options (VGA, DVI, etc) have a high enough pin count, so I thought I'd use a DSUB37 cable, with panel mount connectors on either end, but I've had no luck finding a cable of that length.

Would any of you have ideas for solutions?


texts:
I have the following circuitry:

PWM-2V8 is a square 50% 40kHz signal as this (R37 not populated on this capture):

On P8, I get the following signal which is distorted and the duty is more like 65%:

Q1 = Q2 = 568-8001-1-ND

Q3 = 568-6084-1-ND

I have tried R37=0 and R38=1k but it's still the same problem.

Can anyone explain to me what I don't get 50% at P8 and how I can fix it?


texts: LDO outputting low voltage. LDO or auxiliary components fault?

texts:
I burned a circuit by applying reversed polarity voltage. I measured the LDO that is supplied with 5 V and should output 3.3 V, however it only outputs ~2 V.

Now what can I deduce from that? I would expect the semiconductor LDO to not output anything after being burned, however it does. Could this mean that some of the auxiliary components (capacitors) are blown?

LDO in question is a XC6201P332 (datasheet)


texts:
I am having trouble communicating with an microSD card with an AVR on a board I'm working on. I used an oscilloscope to have a look at the signals coming out of the microSD socket on my board. I saw nice 3.3V MOSI and SCK signals between the AVR and the microSD socket. What I saw on the MISO trace however surprised me. It looked kind of like a superposition of the MOSI and SCK scaled down to under 100mV. My interpretation of this is that the MISO line must be floating and what I'm seeing on the scope is basically cross talk / AC pickup from adjacent signal traces.

The possible causes of this that I've come up with are:

The Slave Select trace is not making it all the way to the SD card (i.e. either the SD slot is not well connected to the board on that pin or the card is not making good contact within the slot)

My reasoning on this is that if the card were powered and the Slave Select pin were low the card would actively drive the MISO line (i.e. it would not float).

Likewise for the 3.3V power or GND signals to the card

My reasoning on this is that if the card were not getting power / GND, it wouldn't matter what was happening on the SPI bus.

My questions are:

Are the conclusions I'm drawing sound based on the information I've provided?
Are there other possibilities I've overlooked?
How can I isolate / diagnose the problem further?

Edit #1

The following scope trace illustrates the description I gave above:


texts:
Why are LEDs on after executing this? LEDs on pattern is 1010:

module test(input clk,
input reset,
output reg[3:0] ledss

);

wire[4:0] dataread;
assign dataread=4'bzzzz;
always @(posedge clk)
begin

    if(dataread)
    begin

            ledss<=4'b1010;

    end

 end

endmodule


texts: Why is it safer to not short left and right audio jack outputs together?

texts:
I've read that the best way to "mix" two left and right line-level stereo jack outputs is to first connect each to a 1k resistor and then to your mono input.
Why is this preferred over just shorting them directly together and then connecting them to a single input?


texts: I'm trying to write bootloader code and I needed to be able to use an address in flash memory as a flag to the bootloader to let it know if it should enter bootloader or the application. I'm able to write a value into the flash address but  I'm having issue with the bootloader clearing that flag at that flash address. I was wondering if there's a way to erase a certain address rather a sector in flash or if there was another way to use a register or flash address as a flag that can be set and cleared. The mcu I'm using is STM32F407vgt6.


texts: Is it a good idea to use potentiometer to measure angle?

texts:
I'd like to measure an angle between two elements on hinges using arduino. Can I use a rotary potentiometer?

If I take reading at two edge positions for calibration (0 and 90 deg.) can I assume that the resistance will change linearly between those positions?


texts:
For an application I am trying to get a switch running using the KSZ8895 (standalone). For testing, at first, I connected it only to MagJacks.

If I test the circuit and connect two PCs, this worked (tested with simple ping).

This works:

PC1 <-> Switch (KSZ8895) <-> PC2

But when I try to connect a PC over my switch to another switch, this fails.

This does not work:

PC1 <-> Switch (KSZ8895) <-> Another Switch <-> PCx

The two LEDS on my switch, which are connected to another switch are blinking synchronously at ~1 seconds intervals.

Does anybody have any idea what's going wrong? Is there a fault in my circuit?


texts: How to wire an outside switch with separate load compression glands

texts: I have a remote control outside switch (Knightsbridge IP663G) which splits a mains line into three, its taking a uk mains cable through the left and I want to connect another mains cable (for lights outside) through one of its three outputs. The confusing thing is it has different load compression glands. One is rated 8A and the other two 2.5. Aren't plugs rated for 13 Amps here in the UK? Why is this being lowered through the switch? Is it ok to wire an outside plug to the 8A gland?


texts: What specifies how much energy can be disspated in an IGBT when switching off?

texts:
I am driving an inductive load with an inductance \$L = 500\mu H\$ with a steady-state current of \$I = 300A\$.  I would like to switch this current off quickly, and I plan on using an IGBT to do so.  Assuming that the time constant of the load \$ \tau = L/R \$ is much longer than the switch off time of the IGBT, we can assume that upon switching off the IGBT, the stored inductive energy \$ E = \frac{1}{2}LI^2 = 22.5J\$ will be almost entirely dissipated into the IGBT.

My questions are:

1) Is my logic above correct, i.e. in assuming that in this case there will be \$E = 22.5J\$ dissipated into the IGBT.

2) What spec in a specsheet determines what the maximum value of \$E\$ is before damaging the transistor?


texts:
Note: All the questions below are extracted from A Novel Wide-Temperature-Range, 3.9 ppm/ C CMOS Bandgap Reference Circuit

I could not post all the imgur picture links as I am limited to two links only.

What is the purpose of R1 as in Fig. 1 of the paper ?

Image Source
For equation (6) in the paper, I am wondering where the extra term "VG(T)" comes from to be part of Vbe(T) ?
What is the purpose of the MosCAP (MPa8) connected to "Out" in opamp topology below ?
Are there ways to derive maths equations for "biasp" and "casp" ?

 Image Source


texts: Separate amplified speakers for landline phone

texts: I want to connect the landline phone handset speaker to some amplified speakers. the idea is to splice the speaker output to a switch, then switch between the handset and the amplified speakers via a 3.5mm jack. just like the old Charlies Angels set up in the 70s. The reason is that my mum is hard of hearing now and does not like technology. Likes to keep it simple, to a point I'm thinking of a 70s TV as well. But the modern handsets with speakers still don't cut it and she can't use the phone because she cant hear them without the speaker and still struggles with turning the speaker on. This way I can keep it switched on and only turn the speakers off when someone else is using the phone. I can't find anything then just has a numerical dial pad with a 3.5mm jack coming out the back.


texts:
I have seen some boxes (with some capacitor circuits inside) which do single-phase power supply to 3-phase power supply conversion. The problem with them is that they cause the load motor to heat up, because the phase difference between the legs is 90 degrees instead of 120 degrees.

Is it possible to design a circuit that produces the third phase with exact 120 degree phase difference using only the original single phase?

Is it possible to use the available phase legs equally to produce the third phase, so that loading on a single phase is avoided?

How would this circuit look?

Note:
The motors in question are 3.7 kW-5.6 kW induction motors.


texts: Can I use a 12V battery charge controller to "ballance" two batteries?

texts:
I have a simple question which drives me crazy and I'm really hesitating to test it, this is why I ask for your opinion.

At home I am using a solar system, using solar panels and a battery. The panels are connected to a charge controller and the charge controller takes care of the battery. So far so good. It's working perfectly and nice since years.

I have still two charge controllers left im my toolbox and there is still a car battery left. Now I was thinking I could utilize that stuff to use abundant power. On sunny days the panels create more electrical current than what I could store in my battery.

My Idea was now to setup a second system with the new battery and the second charge controller. My naive idea is to connect the first battery to the solar input of the second load controller. If the Voltage of the first battery is high enough, the second controller should start loading the second battery. In Theory the (PWM) charge controller should "think" there is a solar panel installed and should load the battery.

After thinking about that for a while I thought that maybe the current of the big battery is a problem. Solar panels are "naturally" limited in electrical current while the battery could maybe kill the charge controller!?

Does someone of you know if charge controllers limit the current inside? I know that there is lot's of ready made battery ballancers out there on the market. But I just want to make use of the spare parts and the second battery.

Thanks in advance

Jack


texts: Making A USB Charge Cable (to replace 2.4V power supply) - Buck Converter?

texts:
I have battery-powered hair clippers that charge with a 2.4V 2000mA AC adapter.  I'm looking for the best possible way to lighten or eliminate the adapter, as the one that was included is huge and very heavy.  Ideas:

Ideal would be if I could use a 2400mA USB charger (i.e. http://amzn.to/2dRxKAz), and somehow make a small converter/plug to step the voltage down from 5V to ~2.4V.  That would eliminate the need to travel with a 2nd adapter entirely.  Is there a way to do this safely?
A less ideal approach could be to use a universal AC adapter capable of 3V / 1000ma (i.e. http://thd.co/2donCwf).  As I understand it rounding up to 3V should be ok, and since it's just charging - not running - supplying 1000ma instead of 2000 would only mean it charges more slowly (which is fine).

Thoughts would be greatly appreciated.

Edit:

As per a very helpful comment, I believe #1 can be done with a buck converter (i.e. http://ebay.to/2eb2mg9) set to output 2.4V.  To its input I would attach a micro usb port (http://ebay.to/2eg52oZ), and to its output I would attach the clippers' charge plug.

I've also read that to make the charger identify the port as a higher-amp 'charge port' (aka to tell it to supply more than 500mA), I should short the 2 data pins together in the micro USB port (reference: http://bit.ly/2dCbGEM).  Does all this sound like it would work?


texts:
I was given a problem, the conditions are:
The voltage and current for a device (using the passive sign convention) are
    periodic functions with    \$T=100 ms\$ described by

\$v(t)=\begin{cases}
10\,V & 0\,ms<t<70\,ms\\
0 & 70\,ms<t<100\,ms
\end{cases}\$

\$i(t)=\begin{cases}
0\,A & 0\,ms<t<50\,ms\\
4\,A & 50\,ms<t<100\,ms
\end{cases}\$

So the questions from the book are instantaneous power, the average power, and  the energy per period, but I have no interest in these, What I really want to know is if
a DC source is connected to the circuit , how can be calculated the average power? a.k.a. What would be the average current (\$I_{avg}\$)?

I understand that the \$I_{avg}\$ would be the given current over the period

\$I_{avg}=\frac{4 A}{100 ms}=0.00004 A\$


texts:
I'm calculating distance from an RSSI, and as it seems to have quite a high variation I want to take an exponential moving average.

My question is: Where in this calculation is it most applicable to apply the moving average filter?

Do I want to take the moving average of:

the RSSI in dBm,
the power in pW,
the distance in m, or
something else?


texts:
I need to up-translate two complementary 2.5 V signals to 5 V. I am looking for a circuit which can do this and which consumes ultra-low static power. I tried to design one, using 4 MOSFETs as shown below:

The circuit uses 4 MOSFETs in a cross coupled configuration to generate the desired signals. However, I was unable to reduce the shoot through current in the MOSFETs beyond a point (Large values of R1 and R2 affects my output rise time) and the circuit is still consuming close to 50 uW at 5V VDD. I am using the output of this circuit to drive other MOSFETs which have a combined capacitance of 1nF. I want the total power consumption of this driver to be less than 10 uW. So, I searched for level shifting ICs on Digikey's and Mouser's websites, but unfortunately couldn't find a part matching my requirement. I found a part from NXP on their website, however they haven't started shipping it yet. I am hoping if somebody could suggest me a better circuit or provide an alternative to the IC I am looking for. Thanks in advance.


texts: Confusion about voltage at negative terminal of capacitor

texts:
I have some confusion about the negative terminal of a capacitor. Consider the following

Now, my understanding was that postive charges accumulate at the positive ("top") plate of the capacitor, setting up an electric field within the capacitor which causes negative charges to accumulate at the bottom plate.

Does that mean that the bottom plate of the capacitor will be at -5V eventually (at steady-state). Or does it mean it will still be 0V?
The circuit simulation tool I ran this with, says it is 5V.

Can someone explain what the negative plate voltage is? And also what happens if there was no ground but another circuit component there?


texts:
I have searched the web thoroughly and find very little info on smps transformers. How to take them apart ... bare bones operations in Power supplies etc. I have a smps that still doesn't work after replacing ALL burnt components. So I'm thinking the transformer bit it as well. AFter blue ring testing seems the thing is toast. Took it apart to rebuild.
Noted as much as I could and remembered the rest.
This transformer is pretty simple ... 2 primaries and two secondaries ... primary one (pins 1 & 2 ) is from the mains measuring approx 165V and is part of the main switching transistor to produce +18V and -18V on it's secondary which of course has a center tap on secondary for the split supply.
The 2nd primary is for the 5V supply for the digital supply. It's pins 8 & 9 on the schematic ... it's primary input voltage is the same as the 1st primary on pins 3 & 4.
So when I took it apart the winding ratio's didn't make any sense for the respective ins and out voltages.

Primary 2 ... pins 3 & 4 was approx 44 winds @ 28 awg. It's secondary was 4 winds @ 23/24 awg. This one sorta makes sense. This primary was the innermost wind ... it's secondary was the outermost wind.

The 2nd primary was only 2 winds (possibly 1 wind) and it's secondary winds were not counted but was at least say 20-25 winds. Insulating tape was used between all winds but not sure how thick each layer was so subsequent winds after the 1st weren't known exactly.

So problem is I need secondary voltages of +18 and -18 on the 1st primary and secondary then need 5v from 2nd primary and secondary ... according to what I know about turn ratios they don't line up.

After rebuild 1 I had 5v supply working but found out that priamry one should be attached to pins 3 & 4. Got that fixed ... haven't finished the rebuild at that point. BUT the windings for second primary and secondary don't make sense for +-18V One or two winds for primary and say 20-30 winds dual for split secondary. +-18V

Any help would be appreciated


texts:
I am looking for a lowest V_f possible Schottky diode out there for logic circuits in my designs. So far the best thing I came across is MCL103. It has 200 mV of V_f at 1 mA current. I am not looking for a high current diode (10 mA top is fine) or high blocking voltage one (10 V is fine, although the higher the better). Lowest forward voltage is crucial. What do you use for this end?

Edit: the application:
What I need the diodes for is simply to allow current flow only in one direction in glue logic circuits. Because of that, I need a cheap solution in a small form factor. Ideal diodes are too expensive and too big. For example, making an open drain like output from an push pull output, etc.


texts:
In the present day processors more than one level of memory is present for trying for the realization of an ideal memory system and to do more work for clock cycle more than one instruction is in the pipeline of execution by exploiting the ILP (Instruction Level Parallelism).

My question is, upon a cache miss, what happens? i.e., whether the instructions prior to and instructions after the instruction causing the cache miss are stalled or only the instructions after the instruction causing cache miss are stalled?

I know that the cases may arise depending on whether the processor is having speculative and out-of-order execution and if the processor also have the ability to exploit the MLP (Memory Level Parallelism).

I want to know about the cases of processor having MLP and not having it

I was not able to find helpful information.


texts: What are my power requirements for my second resistor, and did I do my first's power calculation correctly for my first LED floodlight design?

texts:
I'm planning to build my very first DIY portable floodlight which will consist of a Cree XP-L V6 LED, heatsink+fan, and a 12V power source (two sets of a 8 C battery series in parallel).

I plan to make resistor #1 a static one, to compensate for the LED's dropout voltage, and the second resistor to be variable so brightness can be finely adjusted.  Both of the resistors would go on the positive lead, between the fan and the LED.  The fan and LED will be connected in parallel.  See this 'schematic' below.

According to the datasheet for the LED, the forward voltage is 3.35V for a forward current of 3A.  So doing that, I calculate my required resistance; 12 - 3.35 / 3 = 2.88.  Therefore I need a 3 Ohm resistor for Resistor1.

I then went straight to calculating for power handling requirements.

For Resistor #1:  Seeing how I am using a 12V input, and need 3A of current, it seems to equal 36 Watts of power, meaning I should go with a 40W or 50W resistor.

Now, what's the power requirement for Resistor #2; is it again at least 36W, or can I get away with less?


texts:
I have to randomize a 32 bit (member of a class used in my test bench - non synthesizable logic)value such that number of ones in that is always less than N(say 4) using system verilog constraints.

class random_error;
    rand bit[31:0] Var1;
    constraint random_errorc { Var1 .... };
endclass

How to define a system verilog constraint which will make sure the var1 has not more than 4 bits.

This is system verilog problem and not a verilog.


texts: DSPIC33 SPI Master chip select line not working

texts:
Ive been trying really hard to get the SPI bus working on a DSPIC33EP128GM604. Ive configured SPI3 as a standard 8 bit master module and have designated a chip select pin so I can toggle slave devices.

I cannot get the chip select line to work properly, it seems as if the DSPIC does not wait for transmission to complete before toggling the chip select line from LOW to HIGH. Ive checked the Erratas and nothing seems relevant to this problem. Furthermore ive tried to swap the CS line to some other pin. Ive also tried SPI module 1, but problem persists.

Here is my code:

SPI 3 configuration:

void Init_SPI3 ( void )
{
IFS5bits.SPI3IF = 0; // Clear the Interrupt flag
IEC5bits.SPI3IE = 0; // Disable the interrupt
// SPI1CON1 Register Settings
SPI3CON1bits.DISSCK = 0; // Internal serial clock is enabled
SPI3CON1bits.DISSDO = 0; // SDOx pin is controlled by the module
SPI3CON1bits.MODE16 = 0; // Communication is word-wide (16 bits)
SPI3CON1bits.SSEN = 0; //No CS
SPI3CON1bits.MSTEN = 1; // Master mode disabled
SPI3CON1bits.PPRE = 2; //Pre-scaler
SPI3CON1bits.SPRE = 8;//Pre-scaler 2
SPI3CON1bits.SMP =1; // Input data is sampled at the middle of data output time
SPI3CON1bits.CKE =0; // Serial output data changes on transition from
SPI3CON1bits.CKP = 0; // Idle state for clock is a low level;
SPI3STATbits.SPIEN = 1; // Enable SPI module
// Interrupt Controller Settings
IFS5bits.SPI3IF = 0; // Clear the Interrupt flag
IEC5bits.SPI3IE = 1; // Enable the interrupt
}

SPI 3 Pin configuration:

TRISBbits.TRISB10 = 0; //Set SPI3CLK as output
TRISBbits.TRISB11 = 0; //Set SPI3DATAOUT as output

RPOR4bits.RP42R=32;  //SPI3_CLK out
RPOR4bits.RP43R=31;  //SPI3_DATA out

Chip select line pin configuration:

TRISBbits.TRISB4 = 0; //SPI3 CS is on Pin B4, set it to Output

Simple main routine:

    while(1==1){

    PORTBbits.RB4 = 0;//Set CS line to low
   WriteSPI3(0xaa); //This is from the peripheral library to be safe....
  PORTBbits.RB4 = 1; //Set CS line to high
                    }

But here is the output:


texts: How does a computer control electric circuits?

texts: I would like to know how it is posible for a computer command to phisically start something like a motor or spotlight when they are on such a different scale. How can such a small signal have such a huge effect?


texts: How to access RAM for use with an FPGA for high performance computing

texts:
I am exploring the idea of using an FPGA for linear algebra. I would like the ability to work on large matrices (> 4 GB). But modern high-end FPGAs have RAM on the order of megabytes.

Please describe how I may either:

add external RAM chip
access and use RAM of a connected pc

Any other comments or feedback is welcome.

I currently have a Digilent basys2. I am a beginner.


texts: I need to do some communication between 8051 micro-controller and PC . There used to be a hyper terminal for this purpose in windows XP. I m using windows 8 now. So can anyone suggest me some equivalent of hyper terminal in windows 8  for the purpose of serial comm. between micro-controller and PC.


texts: Diffusion capacitance in a forward biased diode

texts:
I don't understand how the diffusion capacitance is formed in a forward
Biased diode

All websites give the equations but no qualitative description of the reason why
There's a capacitance in a forward biased diode.

What I know is capacitance is related to charge storage so How charge could be
Stored if there is a forward current through the diode?


texts: ARM/Cortex-M comparison data source: Can someone give me a little lay of the land?

texts:
So there are soo many manufacturers making ARM and ARM Cortex-Mx chips and a few of them have I²S and I even saw one with S/PDIF.  This wikipedia article gives me some lay of the land, but I need some hand-holding (or spoon-feeding).

The only hard data I have been looking at is that at ST Microelectronics.

Is there a good central spreadsheet that, even if it's a couple years old, lays out the different ARM and ARM Cortex-M chips from various manufacturers with qualitative details (like has or has not FPU, DSP, 64-bit, I²S or whatever interface) and quantitative details (like on-chip RAM size, cache size, instruction clock rate)?

As you might imagine, I am wondering what chip might be best for audio processing with multiple channels (like 4 or even 8 or even 16 in and maybe 4 out) and with a decent high-speed method of getting the multi-channel samples in and out (if not I²S, something better).

It's not really a mixer, but think of it as if it is. More innies than outies.

I just wanna know where to begin finding and looking up chip data.


texts: How to measure component distances in EAGLE PCB

texts: How do I easily measure how far apart two objects are in EAGLE 5.11.0 Light? Is the easiest way to record the coordinates and subtract?