texts:
I've posted a few question on this forum about ZVF drivers and you all have been a big help and I'm hoping you can help me again. Forgive me if this is a bit long, I just want to be through.

Above is the circuit and components I've used. I deviated from the usual online diagrams so I could run this at a much higher voltage than the usual 12-50v. I have a variac, full wave rectifier and large capacitor bank to hook all this stuff up to. When I work on this I connect my DDM to the cap bank to make sure I know what voltage I'm at. Also, at 100v input I don't draw more than 12amps from the variac.

My first test run worked perfectly. In theory I should be able to turn this up to 150v, but I start at about 20v and stop at 100v because the new parts are kind of expensive and it really adds up when things break. The arcs were starting at about 2" and could be drawn 8-10" apart. So 100V input was good enough for me, tho I am very curious about 150v input. The MOSFET's broke for some unknown reason when I hooked it up to my 8 stage voltage multiplier. I figure the big static field messed them up.

I rebuild the circuit, hook it up and turn it on at 30v. I can hear the high pitched whine of the transformer. All seems good until I go to test it by drawing an arc from the flybacks secondary. The instant I draw an arc it shorts out. Another broken MOSFET. Good thing I have 2 more sets. I rebuild with all new components. Turn it on to 30V, hear the whining, go to test it with an arc, and instantly shorts out again.

So I pull everything apart from both runs and test each individual component. In each run the only thing that broke was one MOSFET. I look at all the wires to make sure nothing is crossed and it all looks good. I even take my old circuit that uses IRFP260N transistors and test at 30V. Works just fine and I can draw arcs with no problems. Does any one know why my MOSFETS keep failing? I'm doing everything exactly the same as my first test run, I don't know why I'm getting different results. Im taking to working two from the failed runs to rebuild it again but im worried they will fail again and I dont know why. If they do I only have one set left and they would be doomed. These MOSFET's are about $20 a piece so I really want some input before I start tossing money away.

Also, can any one tell me the relationship between core gap and power draw?
Seems the higher voltage I go, the more current it draws and the larger the core gap needs to be. If I increase the core gap it also increases frequency. If I don't increase the core gap then it seems like maybe the core saturates and I get very angry chattering sounds when I turn the voltage up higher. If I press on I blow a MOSFET.


texts:
I want to build a Horn antenna to increase directivity of HB100 sensor and I studied principles on an Antenna's book. I started from a void rectangular waveguide.

Since the frequency is 10.525 GHz, the greater side of the waveguide is

$$L = \frac{c}{f_{cutoff}\cdot2\cdot20\,\text{mm}} = 14.28\,\text{mm}\text.$$

It's a very small waveguide, so I ask it's possible to use a smaller cutoff frequency to make a greater waveguide? Dimensions must be about of HB100 board, 40 mm × 46.5 mm.

Second question, to match intrinsic waveguide's impedance with charateristic impedance of air is necessary to increase gradually the dimensions of the waveguide, making it like a pyramid. But, how can I determmine the minimum length that of the horn?

HB100 mechanical drawing:

Dimensions:  40 mm × 46.5 mm

Given the distribution of the antenna patches, the opening of the waveguide needs to be approximately the size of the HB100.

What do you think about a guide of 28mm x 10mm? Fundamental mode is at 5.35 GHz and first higher mode is at 10.7 GHz, that permit a singlemode propagation. The problem is to connect at HB100 a so small waveguide. I thought to connect the guide centered on the arrays, is a good solution? Distance between two elements of array is exact 28mm.

Like this:


texts: How to make a proper DC Power + Battery circuit for audio effect pedals?

texts:
I'm building an audio effect pedal. I need to make a circuit that can either run from DC power or batteries. The key is to disconnect the battery if a DC plug is connected (by using a DC jack with a simple switch) and to disconnect the battery if no mono input plug is connected (with a stereo jack).

I've found this method (and here is a sample schematic). As you can see, when no input plug is connected the negative pole of the battery is disconnected from the circuit's ground, and when there's a mono plug connected it routes the negative pole of the battery through the plug into the ground. This works as expected.

From the other perspective, when a DC plug is connected it disconnects the battery positive pole by opening the switch inside the DC jack. However, this assumes you're using a DC plug with negative polarity (tip negative), but common DC power adaptors use positive polarities, with the tip being positive, so it doesn't works as expected.

I could switch the battery poles to fix the DC switch problem, but that would break the input switch (which would waste the batteries even if no input is connected). So, how to fix it?


texts: DC Motor Controller using only one button?

texts:
I have been trying to create a DC motor controller that can do numerous actions with just the use of one button.

Basically when I click it has to go on way, when I click again it has to stop, and again it has to go the other way and vise versa only using one button. I've been attempting this with a D-FLIP-FLOP, but I have encountered multiple problems along the way that have me thinking new ways to solve it. Any ideas to this silly, but funny problem?


texts: What is this copper thing in my soldering kit?

texts:
I found this copper thing in my soldering kit, but as its in Chinese I don’t know what it is.

What is it? It doesn’t look like that thing for removing solder because the wire is very thin, unlike the other thing which looks like a wick of copper. This looks just like plain copper wire. What is it, and what is it used for?


texts: Need help incorporating a PWM into a circuit

texts:
everyone I hope you're staying safe.
To preface I am a noob at electronics, and I've learned a lot these past weeks. I need help designing with designing a circuit.
To explain my project: I have a Nichia E21A LED (datasheet) that needs to be powered by any 5v power bank and be user dimmable via dial. The PCB and LED will be housed in different modules.

I need components to be sourced off of LCSC for convenience. The LED needs to be run at 3.1v @ 700mA for 242 lm. However, after collimation I need around 100 lumens. This is a colour sensitive use so I need to keep the LED running 90% of current output to maintain colour temp, thus needing a PWM for dimming.
My schematics:

Im using the BP1361 LED driver.
I need the switching controller to fit and able to be mass produced, so no Arduino.
My questions are:

Which switching controller do I pick?
How do I wire it up according to the schematic?
Are my passive component values okay?

Thank you


texts: Wireless transmission/reception through 100 feet  (30m), including concrete wall

texts:
I have an electrical engineering degree, but little experience in building wireless equipment.  I need to transmit a signal through about 100 feet of distance, including a concrete wall.  I need something small that will transmit just a binary "I'm ON" signal when on, and nothing when off.

I don't really care how large the receiver is, but I'd like the transmitter to be relatively small.  The transmitter would really only get a "power on" signal--be expected to transmit when it has power--and then stop transmitting when the power ceased.

Ordinarily for this application I would use some kind of large overkill solution just to use familiar off-the-shelf components.  But very little seems to make it into this concrete enclosure (Cell/WiFi/GPS/etc.)  What might I use?


texts: DC offset of amplifiers for 12V single supply operation

texts:
I want to be able to amplify a signal using op-amps and a single power supply. In order for the op-amps to have maximum swing with a 12V power supply the AC input signal needs to be offsetted to 6V.

After constructing the circuit on a breadboard, the output was not what I expected. I expected the output of the amplifiers to have a wave that oscillates between 5V and 7V, centering at 6V. However, the output I measured was the wave centering at 9V and oscillating between 8V and 10V. The output of the first stage is correct though as I measured the wave oscillating between 5.9V to 6.1V, centering at 6V.

I believe my issue is that my resistor values in the op-amps are too large, therefore not enough current is being fed into the op-amps inputs. I was also thinking of using a linear/ switching regulator to source 6V. Could someone please explain why I'm getting these unexpected results?

Note: LT1006 op-amps aren't actually used in breadboard circuit. LM358's were used instead.


texts:
I'm currently designing a PCB with a boosted audio amplifier. It is powered with a single li-ion cell with 3000mAh capacity. According to the datasheet of the audio amplifier, it is recommended to add a decoupling capacitor C1 as well as an inductor and a capacitor C2 to the inputs V_BATT and V_BOOST. Hereby, V_BATT is the input for the battery voltage and V_BOOST is the input for the booster of the audio amplifier.

In my application, I expect voltage spikes to occur as the battery also drives flickering high-power LEDs that draw 3A - 4A. The flicker rate (on off rate) is about 100Hz.

Now, I wonder if the capacitors and the inductor recommended in the datasheet suffice to protect the audio amplifier from the voltage spikes.

Datasheet:
https://eu.mouser.com/datasheet/2/302/TFA9896_SDS-1381317.pdf

simulate this circuit – Schematic created using CircuitLab


texts: Can ground and voltage terminals be connected by a wire?

texts:
Helo, I am working on an assignment for a circuit analysis class. I have always been a bit fuzzy about the following: Can I assume that the two top terminals are the same node, the two ground terminals are the same node, and effectively connect them by a wire? Or should analysis be done without this assumption?

Thanks!


texts: Will it work long term? (Induction cooker 16 amp to 10 amp adaptor)

texts: Is it safe if I use two adaptors (13 amp and 10 amp) for my 16 amp induction cooker?  I can only plug it on a 220 v outlet.  The first adaptor has a switch though.  The induction cooker worked when I tried but I'm not sure if it can last a long time or if the cooker remains on for long periods.


texts: isolated vs. non-isolated DC/DC converter in PoE

texts:
I am looking at powering a PoE circuit that drives a 24V motor at 2A. I am considering the LT4275/LT4276 LTPoE++™ Controller. I noticed on the datasheet for the controller LT4275 they recommend an "isolated" DC/DC converter but in the eval board documentation they don't mention "isolated" DC/DC converter.

Is an isolation DC/DC converter just mentioned as best practice? What would happen if you use a non-isolated DC/DC converter?


texts: Summing stereo and mono channels passively

texts: I am trying to build a headset for use on my motorcycle which will allow me to listen to my music from my phone (stereo signal) and the incoming sound from my UHF radio (mono i'm pretty sure). what is the best way to passively sum these signals? i wont really need mixing control as i can alter the volumes from the uhf controls.


texts: Controlling a Piston Variable Pump with a Raspberry Pi

texts:
I'm involved in a team that is controlling an AA10VG axial piston variable pump using a Raspberry Pi 3 Model B V1.2. I've been delegated to design the circuit which will control the pump's displacement, but I simply don't understand electrical engineering enough to do so.

We already have a separate 12V power supply which will control various other components of the design as well as a PSU for the RPi. We have an MCP4725 DAC for converting the desired displacement control from digital to an analog signal, but here is where the problem arises: actually controlling the pump.

The pump displacement is varied according to the current of the 12V supply (from 400 mA to 1115 mA). The DAC has a voltage output of 5V with a current of 25 mA. We need to find a way to make the DAC reliably control the pump displacement, but I'm at a loss for how to do so.

I assume that we'll need some sort of current amplifier which can be controlled by the 5V output's current but powered by the 12V supply. I have looked into multiple op-amps and six or seven questions on this site alone, but all of these relate to either constant voltage throughout the system, current-agnostic systems, or are unrelated in some other way.

If this is feasible, please provide details on the symbols in your circuit diagram as I am new to this.

Disclaimer:  I am a computer science student whose team's electrical engineering student has entirely failed to assist in any way, and I've been picked to fix it because I'm the closest to it. Please be patient with my ultimately limited understanding.


texts:
Can AT90USBKEY be used as dev. board for USB host device?

What I would like to try is to use this board to check if I can send SCPI commands to some third party device via USB.

And can this usb miniAB from this dev. board be used to connect to usb type B on that third party device, and if not, how else this communication can be achieved?


texts: What are "slash sheets", and how do they relate to PCB substrates?

texts:
I am trying to specify the stackup for a PCB.  Previously I have used whatever the board house considered to be their "standard" stackup.  This time I am looking at using FR-408 (pdf) because of its (relatively) low cost and (relatively) favorable high-frequency characteristics.

The manufacturer's product page lists three slash sheets for FR-408: /24, /121, and /124.  I see that these are individual specifications found in the IPC-4101 document.

I am assuming that FR-408 meets all three of these specs.  I'm further assuming that any one of these specs may encompass multiple substrates.

Is this correct?  Are cores and pre-pregs always called out by their name ("FR-408"), or can they be specified by simply selecting the appropriate slash sheet?


texts: Is a board with on-board radio disabled an unintentional/intentional radiator?

texts: If a board with the onboard radio (e.g., Bluetooth) chip disabled by software using a jumper, would it be considered to be an intentional or unintentional radiator? That is, the onboard radio can be enabled by flipping a jumper but is disabled in default settings on arrival.


texts: 2D X-Ray Imaging of Surface Mounted Capacitors

texts: Will the imaging yield sufficient details which would outline say an embedded antenna ? Suppose for the sake of the argument the antenna is hidden. Even though it's not. Lastly there will be no electrical transmission through the chip that contain these surface mounted capacitors.


texts: Can this 12VDC Relay be used for Switching 24VDC?

texts:
Can the Songle srd-12vdc-sl-c relay be used with 12VDC on its output?

On top of the relay, it writes 10A 28VDC.


texts: Gate Current Calculation and Practical Mosfet Selection

texts:
Vnoo3 is the drive voltage, and Ig is the gate current. What I am wondering is:

1) How to calculate the peak Ig on the rising edge of the pulsed gate voltage? For instance, using the spice image below. It's a 400kHz "square" wave with a 45% duty cycle.

2) How to use the datasheet to find out what drive current is necessary to be able to drive the MOSFET at a certain frequency? Please provide a real example. I understand the gate-charge vs vgs curve, and how the miller capacitance effects the charging of the gate capacitance, but I am not able to connect the dots to do what my question is asking.

Please let me know if you need more information.

Thanks!


texts:
I am trying to use a MAX487 chip to convert a regular UART signal to half-duplex RS485 signal and vice versa. I am using Atmega328PB as my micro controller. My circuit has no problem with transmission, but it won't receive anything I send from my terminal software. I used my oscilloscope to check out the signal, and I noticed that the signal amplitude is very different when the micro controller transmits the signal versus when the terminal software transmits the signal. Here are my circuit diagram and screenshots.

During transmission, the Atmega328PB's TX enable and the MAX487 Driver Enable pin were set to high, and the RX enable and RX complete interrupt enable were set to low.

During receive, the Atmega328PB's RX enable and RX complete interrupt enable were set to high, and the TX enable and the MAX487 Driver Enable pin were set to low

Circuit Diagram:

Differential signal between pin A and B, referenced at pin B, PC -> microcontroller (RX):

Differential signal between pin A and B, referenced at pin B, microcontroller -> PC (TX):

I tried probing A and B at a time while referencing the ground, and the same thing happened. When uC -> PC, the signal swing between 0 and 1 was 5V, while when PC -> uC, the signal swing between 0 and 1 was approximately 1V.

If anyone has seen this happening before, or knows how to solve this issue, could you please help me?
Thank you very much in advance.


texts: Microcontroller Current Consumption when different internal and external clock modules are used simultaneously

texts:
I am using this Microcontroller - S32K142 64 pin.
From the Figure 4 in this Application Note, We can see there are 4 clock sources for the Microcontroller.
FIRC - 48MHz
SIRC - 8MHz
SOSC - 4-40MHz
LPO - 128kHz
SPLL - 112MHz
From the clocking tree diagram, Figure 4 in the application note attached, I can see that the core clock frequency of the Microcontroller can be derived from any one of the sources like FIRC, SIRC or SOSC and can be upconverted with the help of the SPLL.
My questions :

What is the maximum core clock frequency that the microcontroller SPLL can provide? Is it the 112MHz from the SPLL?

Objective is to calculate the current consumption due to different peripherals (Like I2C, SPI etc) and their clock module sources (like if I am using FIRC, SIRC and SPLL simultaneously)

Regarding current consumption - Suppose I use the 112MHz as the core clock frequency of the microcontroller i.e.HSRUN mode, from Table 13 of the datasheet,I get that, at 25degC, the current due to the oscillator is 112*360uA = 40.32mA? Isn't this a very high value? Am I correct in calculating the oscillator current, this way?
So, If I enable all the peripherals in HSRUN mode, my total microcontroller current consumption would be 52.2mA+40.32mA = 92.52mA. Is this correct?
But I am confused like, what about the current consumption due to FIRC & SIRC usage(suppose if I use FIRC & SIRC clock source also)? Suppose, I also use the FIRC module for some other peripherals, say like SPI at 48MHz. What would be the current consumption due to the FIRC module usage? Would it be 48*360uA = 17.28mA?
And I use the SIRC for I2C Interface (downconverting the 8MHz SIRC to 400kHz). How to calculate the current consumption due to SIRC source?
(The 40.32mA current was only due to the HSRUN mode which derived its frequency from a external resonator of 8MHz and upconverted to 112MHz by the SPLL). So, should I add the currents as I am using 3 different clock sources (FIRC, SIRC and SPLL)?
Please help to clarify - to calculate the current consumption due to different clock source (FIRC,SIRC and SPLL) module usage and peripheral module usages?


texts:
I am trying to complete a simple amplifier project using a single transistor common emitter amplifier. I understand that the common emitter is inverting but I need the power gain to be positive. The requirement is to get +10db power gain but I'm getting -24db since it's inverting. Is there any easy way to make the gain positive? Thanks.

Vcc vcc 0 5

* Input block (DO NOT CHANGE). Your input node is called "vi".
vsig vsig 0 ac 1
Rsig vsig 1 10k
CCi 1 vi 1

* Output block (DO NOT CHANGE). Your output node is called "vo".
CCo vo vl 1
RL vl 0 1k

* Transistor
Q1 vo vi 2 Q2N3904

* Your circuit. Enter your elements below, using vi as the input node, vo, as the output node, and vcc as the power supply.
R1 vi vcc 10k
R2 vi 0 1200
Rc vo 0 7k
Re 2 0 1200

CCe 2 0 1
gp: sqrt(v(vl)*i(rl)/(v(vsig)*i(vsig)))=(-35.6014dB,-89.8774°) at 1000`


texts: HLS: Unrolling the loop manually and function latency constraints

texts:
I have a TOP-level function of the following structure:

struct TYPE1    {uint8 ch[16];};
struct TYPE2    {uint8 ch[100];};

void FUNCT(hls::stream<TYPE1> &inStream, hls::stream<TYPE2> &outStream){
#pragma HLS INTERFACE axis port=inStream
#pragma HLS INTERFACE axis port=outStream
#pragma HLS DATA_PACK variable=outStream struct_level
#pragma HLS DATA_PACK variable=inStream struct_level

TYPE1 inpx;
#pragma HLS ARRAY_PARTITION variable=inpx.ch complete dim=1
TYPE2 outpx;
#pragma HLS ARRAY_PARTITION variable=outpx.ch complete dim=1

inpx = inStream.read();
L0:    for(i<100){
L1:        for(cha<16){
              acc[i] += inpx.ch[cha] * y;
           }
         // do more stuff
         outpx.ch[i] = x; write temp variable
       }

outStream.write(outpx);
}

This top-level function receives a stream of pixels and should process one pixel at a time (per function call); the pixel rate is 528 clock cycles, so the function has 528 clock cycles to work on every pixel. Thus, I would like to place a constraint on the function to have latency no more than 528 clock cycles. At the same time, I would like the function to use as least resources as possible. Since my loop L0 is 100 iterations, I know that each iteration needs to finish withing ~5 clock cycles, if executed sequenctially. Thus, I do not need to unroll L0 loop. With these requirements, I put the following constraints:

#pragma HLS LATENCY min=500 max=528      // directive for FUNCT
#pragma HLS UNROLL factor=1              // directive for L0 loop

However, the synthesized design results in function latency over 3000 cycles and the log shows the following warning message:

WARNING: [SCHED 204-71] Latency directive discarded for region FUNCT since it contains subloops.

Q1:  How do I place the latency constraint on the function while preserving the loops?
Would it make sense to manually unroll the loop by writing all the operations consecutively as below?

{ // manually unrolled L0 and L1
acc[0] = 0; acc[0] += inpx.ch[0] * x; acc[0] += inpx.ch[1] *  y;  acc[0] +=inpx.ch[2] *  z; ........ acc[0] += inpx.ch[16] *  zz;     do more operations on acc[0]
acc[1] = 0; acc[1] += inpx.ch[0] * x; acc[1] += inpx.ch[1] *  y;  acc[1] += inpx.ch[2] *  z; ........ acc[1] += inpx.ch[16] *  zz;     do more operations on acc[1]
.........
acc[99] = 0; acc[99] += inpx.ch[0] * x; acc[99] += inpx.ch[1] *  y; acc[99] += inpx.ch[2] *  z; ........ acc[99] += inpx.ch[16] *  zz;     do more operations on acc[99]
}

Q2: does HLS have limitation on how long (how many) operations can be written on a single line? Will it have a problem parsing/compiling the source code if I write out operations to substitute for loops of say 1000 iterations?


texts: Votage between ends of transmission line

texts:
I have two conductors forming a transmission line like in the figure below (left). Only B is grounded. What is the voltage between B and D at any given moment? If I use a transmission line model (right) then I can compute the voltage between A and B (v(t_0,0)) and the voltage bewteen C and D (v(t_0,L)) using transmission line equations but I can't find the voltage between B and D.

Edit 1: System connection (if it makes a difference): Let's say that A and B are connected to a voltage source and that C and D are
a) left in open circuit
b) connected to a resistance of value R


texts: What is the purpose of this asymmetric IC footprint?

texts:
The IC is the PE42542, a SP4T RF Switch, 9 kHz–18 GHz. It comes in a LGA package with 4 separate ground pads, different pin dimensions, different number of pins on each side, and different pin pitches.

Why is this footprint so asymmetric in pitch and pad dimensions? From this vicor application note, I have observed that the pads are different sizes depending on if they are I/O or power. For the PE42542, I have noticed that the smaller pads (2,7,12,22) are the four RF outputs, while the large ones are GND. I've also noticed that the pins on the IC are grouped with respect to function. However, I would still like to know why Peregrine could not have picked a standard pitch and pad size. It would make building the footprint a lot easier!


texts:
I'm working on a simple project with my Arduino. Recently I had to convert one of my variables to a long instead of an int, and in order to keep things simple I just moved over all the numbers that it interacts with (so I don't have to worry about cross-type comparisons and other math). This seems wasteful, but it's just a clock for myself, and I don't care that much.

It has, however, made me wonder about how much memory I am using. I doubt it's an issue, but I realized I don't know any way to check.

So, is there a way to check the amount of memory being used by an Arduino?

Ideally, I'd like to print out the current memory / total available over the serial connection.


texts: How to flash between two different sets on LEDs using a 556 Timer IC

texts:
I am planning to create a circuit that would flash between two different sets of LEDs (hopefully at an interval of 30 seconds, but at least above 10 seconds) automatically after a button is pressed once, and repeat afterwards until power is disconnected.

               __________________________________________________
Switch _______|
               ___________             ___________            ___
LEDs A _______|           |___________|           |__________|
                           ___________             __________
LEDs B ___________________|           |___________|          |___

Figure 1. Timing diagram.

The goal is to have the power separate, and press a button once to activate. The button itself would not need to be pressed again until the on/off switch is used.

I am going to use 100uF capacitors, a LM556N Timer IC, a simple on/off switch for the power itself, and a push button to start the process.

The LEDs operate at 3-3.2V, 20mA.
I will use either a 3xAA battery holder (4.5V) or a single 9V battery to supply power.

I am confused about how to swap between the timers and at the same time reset the other. So when one timer starts one set of the LEDs will stay on, and then once that timer is done, it will reset then start the other set of LEDs. These will repeat the same process as before.

The full parts list (Most likely won't change it unless I have them on hand):

100uF capacitors

Resistors (I have many different values so the value itself doesn't matter too much)

LEDs (3-3.2V, 20mA)

LM556N Dual Timer IC

3xAA Battery packs or 9V battery and connector

Simple on/off switches

Push buttons

Some NPN and PNP Transistors, will have to check when I get home.

Breadboard to test, PCBs for final products

Side note: I am not planning to use a microcontroller, mostly because I am planning to produce many of these.

Help is very much appreciated.


texts: How to find total voltage in a two loop circuit

texts:
I've been going through the DC Theory textbook by NJATC to learn basic electronics so I can better enjoy my guitar tinkering. But I also want to be able to repair or maybe even build effect pedals and amps. So I'm trying to understand everything that comes my way.

This book gets into superposition theorem, which is all good as far as finding currents. But then it goes into finding total voltage for a two loop circuit and that point it either skips an important step or introduces an incorrect value, after which it is simply useless because there is no way I can replicate their results without knowing how to derive that value (which they do not explain).

My questions are:

1. "How do I derive the value at I1?"

2. "What is the correct value at I1 so I can check my work?"

Here is the circuit:

Here is the page (figure 22-6) where they introduce a seemingly arbitrary value for the current source I1 of 0.4A where the 24v battery would normally be. That value is used repeatedly to derive the total circuit voltage on the following pages. (They actually use the inserted value  of 0.4 (p263) to derive the values that add up to 0.4 (p265). (Lovely example of circular reasoning and bad editing.)

The values I derived for the combined circuit are as follows, with a positive number denoting flow from the direction of the 48v battery (right hand) and a negative number denoting flow from the direction of the 24 volt battery (left hand). R3 has both flows travelling together in the same direction.

Total Combined Values : E, I, R

R1: 28.17 V, 0.031 A, 900 ohms
R2: -4.17 V, -0.002 A, 2400 ohms
R3: 19.83 V, 0.033 A, 600 ohms

Here are the rest of the pages, to show what the book is trying to teach:


texts: standard ethernet pinout for M12 A coded

texts:
I would love to follow the most common pinout (I design connector and receptable, but you never know).

I find conflicting sources:

-RJ45 connector exact same pinout number by number:

-A big cable producing brand Turck seems to have another "standard", I did see this at one of our clients:

Or, is there no (de facto) standard?

UPDATE: we are using the Turck standard on all our cables now. This seems the de facto standard.


texts: Possible to replace worn out NAND chips in solid state drives?

texts:
I understand that SSD endurance is typically much greater than advertised and disregarding any form of data recovery, is it possible to replace NAND chips in solid state drives (with the exact same part)?

It is physically possible with a rework station, but is it likely the SSD controller is paired with the IDs of the flash chips? Do flash chips even have unique identification numbers?

Specifically for laptops with non-removable storage like newer MacBooks and notebooks will this be a feasible process that repair shops could undertake?


texts:
A simple interface of MCP23017 with Rpi using I2C lines. Since there is already an internal pull-up resistor of 1.8k on rpi I didn't use any pull-ups n I2C lines.

Running i2cdetect -y 1 on rpi I rarely receive any response from MCP23017. Most of the times it's unresponsive and while trying to debug it on HW level I observed:

SDA line show 3.3V sometimes and sometimes 0.5
SCL line is always 0.5 to 0.7.

When I remove the connection and test only on I2C lines of Rpi, it works as expected. I believe the schematic is fairly simple and should work.

I have created multiple boards and only 1 board works and only 1 MCP responds on the same.
I have tested with both; VCC = 5V & 3.3V but no change in observation.
I have been struggling with this for more than a week and I can't think of any potential root cause now.


texts:
I'm new to electronics and today I've discovered MOSFET transistors. It lets the current flow between source and drain terminals, when the voltage, applied to gate terminal, reaches a certain level. But I want a MOSFET (if it's still a MOSFET) that is normally letting the current flow between S and D, and is cutting the flow when the voltage applied to the gate terminal reaches a certain level.

So what kind of a device do I need?


texts: Open loop gain and Percent Overshoot Relationship

texts:
In the context of control theory, I found a text stating:

"Higher the loop gain of the system, larger is the percent overshoot"

Can anyone show that analytically?
 Consider it to be a second order system.

Edit: Doing the Maths I figured out that for a Step input, percentage peak overshoot is independent of the magnitude of step size, and is related only to damping ratio, zeta:


texts: What technology exists that could activate a small circuit upon high acceleration/impact?

texts: The circuit will fit inside a 12 gauge shotgun shell, be fired from it (with less gunpowder), and will have DC batteries. I'm wanting to conserve battery life until the shot is fired. When fired, I want the switch technology to activate the circuit which will remain live for a long time. Any help appreciated. Thanks.


texts: Board is getting reset when I lower the temperature in Thermal Chamber

texts:
I have a board which I put in the thermal chamber.

I increase the temperature inside the thermal chamber to 85degC. Soak it for 2 hours and note some readings.

Then, when I change the temperature to 25degC from 85degC, it gets reset and then comes back to normal operation within a fraction of second.

Anyone know why this happens and what details do I need to provide to get an answer for this?

The freq used in my board are 8MHz, 32.768kHz, 248kHz, 48MHz and 125kHz


texts: What is the function of these extra capacitors around the bridge rectifier?

texts:
I'm looking at different bridge rectifier circuits and found this one. Capacitors C5-C8 are smoothing capacitors. Both positive DC and negative DC have capacitors C1-C4 linking to both AC lines.

What is the function of C1-C4?

simulate this circuit – Schematic created using CircuitLab


texts: Why is my TPS62162DSGT regulator burning?

texts:
I need a 12V and 3.3V power supply for a circuit, so I designed a regulator onto a board to turn the 12V to 3.3V. I used the TI TPS62162DSGT to do this, and my schematic looks like:

I used the inductor and capacitor BKPB001608DZ2R2MA2 and GRM188R60J226MEA0D respectively along with this small test board:

I soldered up the board using low temp solder paste and a hot plate, which is less than ideal. But I expected it'd be fine for a test. Checking the components, they seem like they are soldered correctly and in place:

I checked all of the connections and found no shorts, and the capacitance is correct. Unfortunately my multi-meter won't measure inductance. I plugged it in, and it worked fine, although the voltage I measured was only 3.26V. I unplugged it and plugged it back in 2 more times, there was a pop, the device began heating, and the housing briefly caught fire. This has happened twice now, so I suspect a design failure on my part, but I've checked the datasheet and TI's "WEBENCH" numerous times, and can't pin it down. Maybe the ground or voltage side is making contact first, but it wasn't grounding through anything so far as I can tell (off the table). I feel like an idiot, but does anyone know what's happening, I can't figure it out. Thanks in advance.


texts:
A few days ago, I received my Anet A8 Power supply (240W, 20A) power supply in the mail. After the second time plugging it in, it blew the fuse and the rectifier.

I found a blob of solder connected to one of the pins where I connected my wires. Is this normal? I don't think that blob should be connected to that pin at all!

The three big pins in the top left connect to this:

This picture shows the burn marks on my rectifier:

This picture shows how the bottom pins are connected:

Thanks in advance.


texts: Loudspeaker transducer FCC certification?

texts:
Is FCC certification necessary for speaker transducers that are sold as assembled units in their housings?
I found information on active speakers needing fcc certification, but what about passive speakers that use external amplifiers? What about UL certification?


texts: USB hub and slave on same pcb - are serial resistors and capacitors needed?

texts:
I'm building a device using

TUSB2046B hub controller
4x FT230X USB to UART controller

First, let's look on Hub controller sample application:

Note D:

  All USB DP, DM signal pairs require series resistors of approximately
  27 Ohm to ensure proper termination. An optional filter capacitor of
  about 22 pF is recommended for EMI suppression. This capacitor, if
  used, must be placed between the hub terminal and the series resistor,
  as per section 7.1.6 of the USB specification.

Then let's look on FT230X sample application:

My questions:

What is the purpose of 15kOhom resistors to ground on first image? Are they necessary in single pcb layout?
How should I connect those two devices assuming single pcb layout with no more then 5cm distance?

This is the most intuitive idea:

simulate this circuit – Schematic created using CircuitLab

And some questions:

Can I safely remove one 27 Ohm resistor on each line? Must I change the remaining one to 54 Ohm?
Is there any difference whether capacitors are 22pF or 47pF?
Are those capacitors necessary?


texts: Direct power from different terminals in a series of batteries

texts:
I didn't find any answer to this simple question, but please correct me if so, and feel free to edit this to be readable or more general (I'm not good at these technical terms in English).

I want to divert power from just a part of a series of batteries, to get different output voltage. Since I've been told since forever that you should not mix good batteries with bad etc. I wonder if it's a bad idea because of an uneven power load?

The object in this matter is a 48V forklift, with a battery pack consisting of 24 cells, 2-volt each.

Is it in anyway a bad idea to, let's say, connect a cable to battery number six to get a 12V current, with a 10 amp load?


texts: Loopback on LTC2863 RS-422 transceiver not working

texts:
I am using this transceiver  chip to communicate between 2 devices. Now, as a loop back test I am connecting the Tx positive to Rx positive and likewise for the negative. Ideally, I should get an echo when I send some data via the hyper-terminal. But I get no values.

I then, as a test, reversed the connections. In other words, Tx positive to Rx negative and such. I started getting more sensible repeatable data.

Am I understanding this component wrong ?

update:

Updated to change transceiver part number from LTC2862 to LTC2863, after receiving later information.

update:

I am using the above system where in I am connecting A* to Y* and B* to Z*. Should this loop back work ?


texts:
I am trying to build some device that will emulate the operation of some module in my car.  The input is the 12V logic signal from the trasmission control module.  Basically, the device should take this signal and invert it, with a 2.5 sec delay.  The delay will be created with the help of the astable timer based on LM555 and inverted with the NPN transistor:
Since I am somewhat afraid to load the transmission control module of the car, I wanted to use a high side switch between the transmission module and the 555 timer: .
The input signal is applied to this switch, and the switch activates the 555 circuit.  The circuit works but its activation threshold is rather low - the high side switch is activated even with the 2V of input voltage.  How can I increase the activation threshold (or reduce the sensitivity if the circuit)?  It seems that the input impedance of the LM555 is high so maybe the high side switch is not necessary and an input signal from the transmission module could be applied directly to the timer circuit?
Thanks.


texts: Is it possible to use a ULN2003A Darlinghton array instead of multiple TIP120 transistors?

texts:
Looking at the datasheets, I'm not sure their specifics match;
TIP127 and ULN2003A

My intention is to do something like this, but with the ULN2003A, that I have already:

The reason why is that I want to remove the provided driver/power supply (5V 12V, driving 6 LEDs 0,25W each) and use PWM with the RPi to dim the strip's leds (using an external 5V power supply). I've already done this to regulate a 12V fan (but I understand this is another story).


texts: How to create counter with unique sequence

texts:
I have a sequence: 001, 110, 010, 001, 110,  etc.

Although there are 3 bits that I want to represent, only 2 are needed for states (3 states). What I get confused with, is utilizing only 2 state bits if we need 3 output bits. Can anyone clarify this?


texts: Detecting opens/shorts when driving coils

texts:
Using software while PWMing a coil with feedback going to an A/D input,

1)  how can you detect a state where the coil is an open circuit?

2)  how can you detect a state where the coil is a short circuit?


texts: what driver chip do i need for a irf4905 p-channel mosfet

texts: I'm trying to figure out what chips I need to run my irf4905. the mosfets will need to be running 5 amps at 24 volts using pwm to Varey the watts. if anyone has done anything with this mosfet an knows what drivers it need anything would help


texts: Hardware ID - Variant detection with 1 Digital MCU pin

texts:
I have a board, which is the host for several different sensors.
All sensors have the same 4 pin plug with the following pin-out:

Pin: VDD
Pin: Signal
Pin: Free
Pin: VSS

Means, I got 1 free pin, on each plug.
All plugs / sensors should be interchangeable and the MCU should be able to determine, which sensor is plugged in.
My MCU, does not have enough analog pins left, otherwise I could so something like put a voltage divider on each board and read the analog value.
I have still enough digital pins left.
I would like to be able to determine at least 20 different kinds of sensors, better 32.
Is there a neat little trick, to achieve this?

Some other SE questions, that are on a similar topic, but did not solve my issue:
What is a good way for the mcu to determine which hardware version it is running on?
Encoding version or configuration on PCB


texts: PCIe, diagnosing and improving an eye diagram

texts:
I have implemented a design that uses PCIe. It is somewhat different in that the PCIe interface is used as a chip-to-chip communication lane on a single PCB (e.g. no PCIe connector).

The root complex device is a Freescale i.MX6 which is PCIe Gen 2 compliant and the device I am communicating with is a Marvell WiFi module that is a PCIe Gen 3 compliant device. It's a single lane interface running at 2.5Gbps.

I've done some signal integrity measurements by soldering a high speed scope with proper differential probles right on the other side of the inline caps shown below:

For the clock the eye diagram looks quite good:

But the TX data not so much:

The WiFi chip has on-chip terminations so I don't believe I am supposed to need any additional terminations, but I could be wrong about that.

I have found some registers that can be set within the i.MX6 processor for the PCIe peripheral but I'm not exactly sure what they actually do. A little bit of trial and error hasn't gotten me very far either.

I've checked that the layout follows proper routing rules and the PCB was constructed with the correct impedance. Obviously I have some jitter in the system but it also looks like I have a reflection or de-emphasis issue. I'm hoping someone could describe what they see wrong with my eye diagram and/or suggest some ways to fix it.

Cheers!


texts: Can't figure out this seven segment display

texts:
I recently bought four of these seven segment displays: http://www.electrokit.com/en/leddisplay-7segment-58mm-red-green-ca.49450

I'm having no luck however to make it to work, and since there is no datasheet for the display I'm stuck.

The only thing I've managed to light up is the decimal point. My setup to light the decimal point can be seen below. Note that there are 10 pins on the display, five at the bottom and five at the top. The pins have been aligned to the right of the breadboards (so the red wire is currently attached to the rightmost pin at the bottom).

The red wire is hooked up to the 5v output on the arduino and the blue to the ground. As can be seen the decimal point has been lit up in green, and if I move the red wire four pins to the left the decimal point turns red instead.

Thanks!


texts: Best method to transfer two int percentage values over a CAN bus

texts:
I have two integers:

int A is a value from -100 until 0  and
int B is a value from 0 to 100

What is the most effective way to put this into a CAN message and decode it again at the other microcontroller?

For the CAN message I have this structure:

typedef struct
{
    uint16_t id;
    uint8_t length : 4;
    uint8_t data[8];
} CANmessage;


texts: Creating a logic function of a burglar alarm system for a bank

texts:
This is the problem from homework that I am stuck on:

  A burglar alarm system for a bank is to be operative only if a master
  switch at the police station has been turned on. Subject to this
  condition, the alarm will ring if the vault door is disturbed in any
  way, or if the door to the bank is opened unless a special switch is
  first operated by the security guard's key. The vault door will be
  equipped with a vibration sensor that will cause a switch to close if
  the vault door is disturbed, and a switch will be mounted on the bank
  door in such a way that it will close whenever the bank door is
  opened. Symbolize the above system as a logic function and construct
  the corresponding logic diagram.

So, I created an outline to list the conditions and the actions:

Conditions:

A = Master switch is turned on
B = Vault door is disturbed in any way
C = Vault door is opened
D = Special switch is 1st operated by security guard's key

Actions:

W = Burglar alarm system becomes operative
X = Alarm rings
Y = Switch closes
Z = Switch mounts on bank door in such a way it will close the door

And here's the truth table:

\begin{array}{c c c c|c c c c}
   A
 & B
 & C
 & D
 & W
 & X
 & Y
 & Z \\
\hline
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\
0 & 0 & 0 & 1 & 0 & 0 & 0 & 0\\
0 & 0 & 1 & 0 & 0 & 0 & 0 & 0\\
0 & 0 & 1 & 1 & 0 & 0 & 0 & 0\\
0 & 1 & 0 & 0 & 0 & 0 & 0 & 0\\
0 & 1 & 0 & 1 & 0 & 0 & 0 & 0\\
0 & 1 & 1 & 0 & 0 & 0 & 0 & 0\\
0 & 1 & 1 & 1 & 0 & 0 & 0 & 0\\
1 & 0 & 0 & 0 & 1 & 0 & 0 & 0\\
1 & 0 & 0 & 1 & 1 & 0 & 0 & 0\\
1 & 0 & 1 & 0 & 1 & 1 & 0 & 1\\
1 & 0 & 1 & 1 & 1 & 0 & 0 & 0\\
1 & 1 & 0 & 0 & 1 & 1 & 1 & 0\\
1 & 1 & 0 & 1 & 1\\
1 & 1 & 1 & 0 & 1 & 1\\
1 & 1 & 1 & 1 & 1\\
\end{array}

It is the last three I am not sure about:

What happens if the door is disturbed AND the special switch is first operated at same time?  Would the alarm still ring?
Would the vibration sensor still be activated when the door is opened (i.e., what would happen if the door is open and is disturbed at same time)?

I am not very knowledgeable with how bank security system works, so it would be nice if anyone can explain about it.


texts: The induced-emf formed in a solenoid connected with a battery

texts: When a solenoid is connected with a battery and then the circuit is switched on, there would be an induced-emf, and after some time, this induced-emf will vanish when the current reaches maximum value, I was excaliming what will happen exactly to this induced emf during the build-up of the current until it reaches its maximum value? I don't understand how would it decrease until it became zero? Could you please explain?


texts: P-Channel Mosfets in Series to Increase Max Drain-Source Breakdown Voltage

texts: Would there be any problems with putting two P-Channel MOSFETs in series in order to double the maximum operating voltage for drain-source?  The body diodes when used this way should act just like ordinary diodes put in series to handle more voltage, correct?


texts: Understanding "Leading/Lagging" and "Phase Shifting" with Sinusoidal Functions?!

texts:
INTRODUCTION/QUESTIONS:

I'm reading through a chapter on sinusoidal alternating waveforms and I'm having some difficulty in the section on Phase Relations. The generic expression is mentioned below for a waveform that has been shifted. Following that I posted a list of expressions that show their geometric relationship. Can someone explain the list of expressions in your own context or understanding.

I do not understand these angles and/or functions. Their meaning as well as their context in phase shifting is confusing to me. I need a better foundation of understanding to have a better intuitive approach towards problem solving. I've had Calculus 1 and I'm currently taking Calculus 2. Therefore, I'm familiar with trig functions but I just can't bring it all together.

I would of posted this in the mathematics forum. However, I felt receiving guidance/direction from an engineers point of view may be more beneficial.


texts:
Lets say I have a lossless coaxial cable with a characteristic impedance of 50 ohms. The length of the cable is very long compared to the the wavelength of the relevant signals on the coaxial cable. This is an obvious transmission line.

Now, lets say I attach an ordinary 50 ohm through-hole resistor to the end of the transmission line by attaching one lead of the resistor to the inner conductor of the coaxial line and the other lead of the resistor to the outer conductor. From what I have learned, this should result in no reflections in the transmission line when a source generates a signal at the other end of the coaxial cable because the transmission line is matched to the load.

In this situation, what is happening at the junction between the coaxial line and the leads of the resistor? Would the leads of the resistor (although very short) not make up a sort of transmission line with its own characteristic impedance? I know that characteristic impedance is not dependent on length of the transmission line, but if characteristic impedances do not match, there will be reflections. Why would there be no reflections?


texts:
I have this bulb, that I didn't buy myself, and I don't have the packaging, nor do I know the price or anything. The writing says:

SOFT STYLE Lighting LB443 Standard 6W E27 3000K 230W/50Hz CE

I feel quite sure it is LED, simply because when I turn it on it is at full capacity right away, unlike the energy saving bulbs in the past that took some time to get up to full capacity.

What do you say, can I trust that this is LED?

The part with the fins is porcelaine. The glass is glass, not plastic.


texts:
I am wondering if anybody has ideas for developing an (Arduino?) system that would use RFID to log occurrences when two people are in close proximity to each other (e.g., <= 1 meter). Ideally, I would like to construct something that would operate in a manner very similar to the OpenBeacon system (http://www.openbeacon.org/) -- and, preferably, the events/data would be transmitted via wi-fi in real time.

My ideas are as follows, so any feedback or alternative solutions would be greatly appreciated. (Please keep in mind that I am not an engineer!)

I am thinking of using a wi-fi enable microprocessor (e.g., Arduino Yun) that would serve as the reader or detection system. For beta-testing, this device could be set in an enclosed case and attached to a belt. I presume it would require a fairly robust battery supply. The other person would be wearing an RFID tag that has a range of <= 1 meter and would log the event. Ideally, a reading would take place roughly every 30 seconds, and the captured event would be transmitted over wi-fi.

Here are a few other things to keep in mind:

The people using the hardware should not have to do anything other than simply wear the constructed devices.

The reader itself should be as small as possible.

My ultimate goal is the data logging of the proximal events.

I am certainly open to other technologies, as my ultimate goal is simply the proximity detection with data logging (preferably via wi-fi).

Thanks in advance! Brian


texts: Infinite hexagonal impedance network with loads at specific nodes

texts:
It's been a couple weeks already that I am trying to solve this network on the paper. It consists on a infinite/periodical hexagonal lattice but with some peculiarities. First of all, this is not the same network as the one asked here
My network can be seen in the attached figure. At each vertex of the hexagons, a load ZL is to be placed. Zs is unknown and I would like to calculate it in order to maximize the power transmission from point A to point B, for example.

It is obvious that the impedance seen from A is the parallel of the three branches. After the first impedance Zs at each branch, the impedance seen right afterwards will consist of the parallel of two branches and ZL. Since the network is infinite, I have considered that the impedance seen from each branch will always be the same.

Therefore, I would have a simple calculation.

First, I assume that all impedances are real.
If I want maximum power transfer to the network from point A as an input, the impedance seen from A should be equal to ZL (since the conjugate of a real number is the number itself). This gives us: Zin = Zbranch/3= ZL
The impedance seen from each branch would be the series of Zs + the parallel of ZL and two branches. Namely:

\$ Zbranch = Zs + ZL*Zbranch/(2*ZL + Zbranch)\$

After substituting the value of Zbranch that can be extracted from 2), I get a value of 12/5*ZL for Zs.

In my head it results so simple that I do not believe this result is correct. However, I cannot think of a more complex analysis.
Could you provide me with some feedback and maybe any more complex technique for analysing this network? Thank you


texts: AVR diagram of functions calling, ISR and main loop share the same resource

texts:
I made a simple diagram of functions calls to illustrate the potential problem which bothering me a little. As you can see, my task_list (which is simple linked list) is modified either in ISR and program main loop.

Can this solution cause errors in the future?
What kind of errors?
Should I use some kind of synchronization/resource protection solutions to prevent errors?
What kind of synchronization?


texts: Using flyback diode with relay, load regulation faults occur

texts:
I'm having a problem with load regulation errors on my board. When I engage our load with a relay, it causes a metering chip in our system to reset. I've placed a picture of the relay with the flyback circuitry below.

Some detail on the project:

The project details are sensitive, so we can only put so much online. But, let me know if you need any more specific details.

We are controlling LED light ballasts.
We are specifying

the ballasts may draw up to 16A
the ballast shall range from 85 - 277VAC, single-phase

We are using a relay to disconnect the lamp from the AC line.
The relay is in a normally closed configuration.
We are taking the 90-267VAC down to 5V with a simple AC to DC converter and using that to power our system.
We are metering the line using an IC meter.

Test Setup:

For the sake of having reproducible results, we thought to use a large wattage rated resistor on an actively cooled heat sink to act as a constant load.

The resistor is 500Ω rated for 150W
We are running the system off of a BK Precision power supply that seems to drift by maybe 0.5VAC @ 120VAC (spec'd at 0.2% ±0.6VAC)
The system draws about 0.249A of which about 25mA belongs to our circuit.

Symptoms:

When the relay is engaged, the load is disconnected, we see a ringing on the 5V line as well as on a regulated 3.3V line.
When the relay is disengaged, we see the same ringing, but much more exaggerated. This is primarily when the metering chip resets.
If we disconnect the load from neutral using a normally closed momentary switch, we see some 5V and 3.3V line voltage regulation errors. But, it very rarely causes a fault in our DC system as a whole.

So I was wondering if you can help me understand what I'm doing wrong in the circuit. I think it's related to the relay so that's the part of the schematic I included, if you need to see or know more, let me know.

Thank you very much.


texts: Is there a physical (electronics) difference between Hue White and Color and Hue White Ambiance bulbs?

texts:
I'm curious if anyone knows if there's a physical difference between a Philips Hue White and Color bulb, which allows the user to set a complete range of RGB colors including white light color temperature, and the Philips Hue White Ambiance bulb, which only allows the user to set the color temperature of the "white" light?

Can Philips use a simpler controller in the electronics or simpler/cheaper LEDs for the white-only bulb?  Or are they simply charging more for the added functionality (lines of code) of setting a complete range of RGB values versus a "color temperature" subset?


texts: Picking an AC-DC Converter to Minimize Cost

texts:
I'm trying to design an AC/DC converter to implement into a project I'm working on.  The project needs to be isolated from mains and shouldn't require more than 1A at 5V.  My question for you is what is my cheapest option for converting 120AC mains to 5V without blowing anything up?  Keep in mind this needs to be implemented on a PCB so simply buying an AC/DC converter won't work for me.

I'm looking for recommendations on different circuit types and especially component recommendations.

(NOTE: I do know the dangers of mains AC.  I have a pretty good knowledge of circuit design but I'm a little lacking in the area of power conversion techniques.)


texts: How to find the transfer function of this digital controller and DC Motor?

texts:
I am studying digital control theory and struggling with a particular diagram of a digital control system. The system is presented below:

\$D(z)\$ is a digital compensator, \$G_{h0}\$ is a zero order hold circuit with adjustable gain \$k_2\$. The blocks \$G_{p1}\$ and \$G_{p2}\$ are part of the DC motor model. The sampling time is \$0.1\$s.

Given the motor parameters, \$G_{p1}\$ is found to be:

$$ G_{p1}(s) = \frac{K_t}{JLs^2 + (JR+bL)s +bR + K_e K_t} $$

and \$G_{p2}\$:

$$G_{p2}(s) = \frac{1}{s} $$

My question is about the \$T\$ symbol in the feedback loop. Should this be included in some way in the feedback loop when calculating the transfer function? For example, below I present my code to find the transfer function of the following system.

    % DC motor constants
    J=0.01; % Rotor momentum of inertia
    b=0.01; % viscous friction
    kt=0.01; % torque constant
    ke=0.01; % electromotive force constant
    k2 = 1; % ZOH gain
    R=1;    % rotor resistance
    L=0.5;  % inductor resistance
    T = 0.1; % sampling time
    s = tf('s');
    z = tf('z');

    gho = (1-exp(-T*s))/s;

    % Transfer Function
    num=kt*k2;
    den=[J*L J*R+b*L b*R+ke*kt];
    disp('Open loop Transfer function velocity control without controller')
    TF_DC_vel=tf(num,den)

    disp('Clsoed loop Transfer function velocity control without controller')
    TF_DC_vel_closed = feedback(TF_DC_vel, 1) . % <---- Should this be 1 or 0.1?

Output:

Open loop Transfer function velocity control without controller

TF_DC_vel =

              0.01
  ----------------------------
  0.005 s^2 + 0.015 s + 0.0101

Continuous-time transfer function.

Clsoed loop Transfer function velocity control without controller

TF_DC_vel_closed =

              0.01
  ----------------------------
  0.005 s^2 + 0.015 s + 0.0201

Converting to Z-domain:

% Z Transfer Function
disp('Z Domain, Open loop, Velocity Control, Transfer Function without controller')
tf_z_open_vel = c2d(TF_DC_vel,0.1)

% Z Transfer Function
disp('Z Domain, Closed loop, Velocity Control, Transfer Function without controller')
tf_z_closed_vel = feedback(tf_z_open_vel,1)

Output:

Z Domain, Open loop, Velocity Control, Transfer Function without controller

tf_z_open_vel =

  0.009056 z + 0.008194
  ----------------------
  z^2 - 1.723 z + 0.7408

Sample time: 0.1 seconds
Discrete-time transfer function.

Z Domain, Closed loop, Velocity Control, Transfer Function without controller

tf_z_closed_vel =

  0.009056 z + 0.008194
  ---------------------
  z^2 - 1.714 z + 0.749

Sample time: 0.1 seconds
Discrete-time transfer function.

More specifically, should the feedback be 1 or 0.1? 1 refers to the normal feedback if nothing was present in the feedback loop while 0.1 would be the sampling time.

I am uncertain which it should be and why. Any suggestions would be appreciated.


texts:
Can somebody clarify what the purpose of D2 is in this schematic:

I understand that we are taking a clock input from the Sync jack to the transistor. The reset pin (4) is pulled high to Vcc, until the NPN transistor is activated (pulled high) and it then drops the pin 4 to GND through the transistor. (Can somebody please clarify if my wording is correct with this description? How could I be more clear when speaking about transistors?)

However, I do not understand what the D2 diode is supposed to do. Is it some sort of protection in the case of an incorrect input at the Sync jack? Isn't that what the de-coupling cap is for?


texts: Does an LCD or LED monitor consume lot more power if the pixels are changing their colors or does the backlight have way more impact on power consumption, which makes changing pixel colors' power consumption negligible?


texts:
I'm having some doubts in the definition of the Buck Converter output power with a RL+EMF load.

Some books just consider the output power to be
$$P_o = E_o I_o$$
i.e, average voltage times average current. But, why? The power dissipated in the resistor is
$$P_R = E_RI_{orms}^2$$
isn't it? Why I can ignore the current harmonics in this calculus. I know that the average current is way bigger than the harmonics. But anyway, is this an approximation? Most books just don't bother explaining this.
Edit: Shoudn't the power in the load be
$$P_o = E_bI_o+E_RI_{orms}$$


texts: Get Li-Ion battery capacity from discharge time (constant load)

texts:
I would like to ask if there is some easy enough way to calculate Li-Ion battery capacity if I measure the discharge time with constant load (not constant current!).

I have made a "discharger" using arduino, relay and 3.9ohm resistor. I measure time from start (4.2V) to 3.3V and then disconnect the battery using the relay. I get the time in seconds on the display.

I know the best way would be saving voltage through the discharge cycle and then get the capacity using integral. My mathematics skill is too low to make it there (maybe programing skill too).

Is there easier way to use? Could I simply do it by:

Voltage / Load * Time

What voltage should I use in this calculation? 3.7V?

Are there any other ways?

(I can't switch to constant current method because I already made the discharger and put some effort, time and money in it. I don't want to leave it and start over)


texts: Why does it take less force to mate a full-detent SMPM connector than to demate?

texts: As seen in the table at the bottom of the page the mating force of a full-detent SMPM connector is less than its demating force.  This is the opposite of every other type of SMP/SMPM connector listed in the table.  Why is this?


texts: How do I power 100 LEDs in series with low voltage?

texts: I just started playing with LEDs and Im trying to make a sign with them. I have the LEDs in series and I have a resistor on each led. I can barely get one letter to light with about 36v( two 18v battery's in series.) I'm clueless about what to do and don't really know how it all works.


texts: Automotive electronic circuit design, Voltage divider to uC ADC pin

texts:
Automotive Circuit requirement:

If input pin is connected to Battery(T87 line), the output of the circuit shall provide a output voltage of 5V to ADC pin of microcontroller, if the input pin is connected to GND, the output of the circuit shall provide a output voltage of 0V to ADC pin of microcontroller and if the input pin is left floating, the output of the circuit shall provide a output voltage of 2.5V to ADC pin of microcontroller.

The battery voltage in load dump condition could be up to 60V, but in normal operation without any fault condition, it would be up to 32V.  Would a simple voltage divider (with a pull-up to 5V) with a blocking diode be enough? Any other ideas? What parameters of the ADC of the microcontroller should be considered? Injection current into the uC- ADC pin would be critical, right?
How do I find out the voltage thresholds?
Also, what are the parameters of the Schottky diode that I should look to select? The diode would decouple the input pin from the centre tap of the voltage divider, because in case the input pin is connected to battery, the injection current into the uC ADC pin would be too high.

I have used a switching diode, since it was already available in the Bill of Materials.


texts: Are lithium ion batteries damaged by strong magnets?

texts:
I'm wondering if it is okay to put a lithium ion battery directly next to a strong permanent magnet.  Would this affect the functioning of the battery?  Can it lead to early failure?  In the worst case, can it lead to an internal short circuit?

In my setup, a small lithium ion battery (100-200mAh, similar to this link ) is used in the same device as a couple of neodymium magnets (N52 cubes, the strongest kind).  The magnetic field at the surface of the magnets is up to 0.6-0.7 Tesla, which is really, really strong.  Due to the mechanical design, the battery has to touch one or more magnets - there isn't any other good place to put it.

I can't think of a specific reason that wouldn't be okay, except that is a strong enough field that it could affect not just ferro- but also paramagnetic materials, and possibly affect chemical reactions so it might mess up the chemistry at the battery electrodes.  Also it is a strong enough field that there isn't any everyday experience with it, hence I have no intuition about what to expect.  The battery certainly doesn't come with a spec for "max allowed magnetic field".


texts: Are external components required for HLK-PM01?

texts:
Apologies in advanced as this is kind of a vague question and due to my lack knowledge in this specific sector. I'm designing a circuit using a HLK-PM01 as the power supply which is a 3W AC-DC converter (240VAC -> 5VDC). The 5V will power some relays and will also further step-down to 3.3VDC through a voltage regulator which will power a MCU. Based on the datasheet of the HLK-PM01, a varistor, capacitor and common-mode choke are recommended to add on the AC side.

I don't really have a problem with the varistor and capacitor as they have a relatively small form factor. However, the common mode choke is quite huge and takes up a large space on the PCB. My question is how important is the common-mode choke?

My second question is selecting the correct common-mode choke. I am sourcing majority of my components from lcsc.com and some from element14, RS-Online and AliExpress. As LCSC is a china store, some of their products don't have clear specifications and I'm not sure what to look for exactly. I found a few chokes but not sure if it is suitable for this application and for AC lines.

UU9.8-10mH, UU9.8Y-10mH, FL2D-Z5-103

How do you identify if the choke is AC capable? Are there any small chokes that can be used for this application? Any help is much appreciated. Thank you in advanced.


texts:
I'm trying to understand if I can use a V1401 ADAT transmitter with the PCM4222 ADC.

datasheets:

Coolaudio V1401

TI PCM4222

They will be communicating by their PCM audio serial port interfaces, using Left-justified mode.
The ADC will be set as master, it will get a master clock from an external oscillator. Doing so, it will generate LRCK and BCK.
V1401 only needs word clock, since it generates its own internal BCK using a PLL (f = 64xWDCLK).

So can I connect V1401 WDCLK input to PCM4222 LRCK output?

my doubts are:

1) for the sample rates that I need, PCM4222 will produce 128*Fs and 256*Fs for the BCK, and V1401 uses 64*Fs as internal BCK. Does it matter? Or I shouldn't care, since they don't share BCK? if so, PCM4222's LRCK would still be at the correct rate for V1401?

2) how should I set WDCLKNEG of V1401 (WDCLK phase)?


texts: How many solar panels would one need to carry to fully charge Tesla model S or S in 20 minutes?

texts:
Some would say carrying solar panels to charge a Tesla would be inefficient, and would take up all the space, however towing a trailer would. Solar panels plus inverter are also not that heavy.

Would carrying a folding device that stacks solar panels in a 3 meter by 2 meter 2 wheel trailer be efficient, especially in a country that does not have fast charging yet, but 14 hours of sunlight in summer and 11 in winter? It is possible to get the fast charger that charges batteries to 80% or more in 20 minutes.

Finally, assuming 400 Watt panels (which I assume are the largest would one have to carry), how much space would it take when charging? Of course one would find a very large open space on the side of the highway, where the device unfolds and charges.


texts: If a mosfet 2N7000 is rated 60v 200mA will it work with 12v 800mA?

texts:
If the mosfet 2N7000 is rated at a maximum 60v 200mA which give us a power of 12W
will it work on 12v 800mA which is a 9,6W?

My question is also about the maxium current rating, is it for any voltage? or it's more like "if I do not go above 12W I'm okay..."

Thanks


texts: Flyback switching power supply flickering debugging and proper software for its simulation

texts:
we are using PIExpert V6 for building one fly-back switching power supply, SO the calculated power supply is this kind:

and the Altium files is here:

source files are here:

source files

or :

 Another link for source files

So the problem is here,When we connect the 220V AC voltage source to our power supply and connect the lamp to output,the lamp becomes on for only one second and then is off, then on then off and so on ... .
So what do you thin about this kind of operation causes and the way for fixing it.

And finally is there any professional software exist for simulating this kind of power supply before building it physically, we could not simulate this circuit in Altium V9 because there is no TNY280PN and the proposed transformator , so if you have simulated this kind of circuit please guide us to the correct way.(Any idea about simulating with MATLAB, PSPICE or ... and examples ).

Thanks a lot for your attention .


texts: What is a boot loader, and how would I develop one?

texts:
I've met many projects in which an AVR microcontroller uses with a bootloader (such as the Arduino), but I don't understand the concept very well.

How can I make a bootloader (for any microcontroller)?

After writing my bootloader, how it is programmed to the microcontroller (like any .hex program burnt on the flash rom of the AVR, or some other method)?


texts: Can the parameter \$\alpha\$ and \$\beta\$ be used for any BJT?

texts:
The reason I ask this question is because the statement in this wiki page. It says

The common-emitter current gain is represented by \$\beta_F\$ or the h-parameter \$h_{fe}\$; it is approximately the ratio of the DC collector current to the DC base current in forward-active region. It is typically greater than 50 for small-signal transistors but can be smaller in transistors designed for high-power applications.
Another important parameter is the common-base current gain, \$\alpha_F\$. The common-base current gain is approximately the gain of current from emitter to collector in the forward-active region. This ratio usually has a value close to unity; between 0.98 and 0.998. It is less than unity due to recombination of charge carriers as they cross the base region. Alpha and beta are more precisely related by the following identities (NPN transistor):

So I want to ask in common emitter or collector, can I use \$\alpha_F\$ as well as using \$\beta_F\$ in common base or collector


texts: Active band pass filter cutoff frequencies

texts:
I am using this active bandpass filter for one of my projects:

simulate this circuit – Schematic created using CircuitLab

I already know the transfer function of Vo/Vi and the voltage gain:

$$ \frac{Vo}{Vi}=-\frac{R_{2}}{R_{1}}$$

$$\frac{Vo}{Vi}(s)=-\frac{sC_{1}R_{2}}{(1+sC_{1}R_{1})(1+sC_{2}R_{2}))} $$

I also know the respective cutoff frequencies:

$$fc_{1}=\frac{1}{2\pi R_{1}C_{1} }$$ (lower cutoff frequency)

$$fc_{2}=\frac{1}{2\pi R_{2}C_{2} }$$ (higher cutoff frequency)

My question is simple:

How can I derivate the cutoff frequency formulas only by knowing the transfer function? I've seen some examples online but none of them included an active band pass filter. Thanks in advance.


texts: Small system on a chip : Power consumption

texts:
This question is lying somewhere between electrical engineering and computer science, however I felt that this forum suited my question the best. I post this question because I feel that this kind of research is quite cumbersome if you don't look at the right places.

I want to mention that my question is not about buying goods, but rather where to search for information about the goods you want to buy, which I think is relevant to know for anyone who would like to build a smaller system on a chip. If there is a better forum for posting this question, please tell me.

I am planning to begin a project building a smaller system consisting of

1) 8-bit microprocessor

2) Some memory (speed is not relevant for my project)

2) Wireless communication unit (Wifi/Bluetooth)

3) Display (about a 2-3 square centimeters, only going to display some static images, and no advanced animations etc, resolution is not the big thing here).

4) Battery

I am not going to build every part of the system myself, and only the programming of the microprocessor will be the hard work from my side.

The thing is : want to make the power consumption of the system as small as possible (so that the battery last longer...), so my question is : How do I estimate the power consumption a system like this / where can i get that kind of information? Of course, the power consumption varies with what kind of components I am going to use, so what kinds of components suits best out of the energy saving perspective?

With the above specifications in mind, I express my first considerations about this below

Processor : The power consumption varies with the clock frequency and if you are giving it operations to perform, so what I am searching for is the average energy per clock cycle / average energy per operation.

Memory : What kind of memories are the most energy efficient?

Communication : Wifi / bluetooth best (read about Ericsson's new low power bluetooth technology, however I couldn't really conclude anything about the overall power consumption)

Display : What display's are the most energy efficient theese days? I have considered E-Ink displays as an effective alternative, but I'm not sure about this.

I am merely a beginner at this, so any input to the problem would be appreciated and if I am missing something here I would appreciate that kind of information aswell. Again, I am not asking for you to explicitly give me the answers to my problems, but where to effectively search for this kind of information. Of course some direct answer would not be wrong either.

Thanks


texts: 5A constant current/ constant voltage using LM350

texts:
I take the circuit below given in a TI application note, and I have some questions about the way the circuit works:

The circuit is designed as a 5A constant current/constant voltage regulator.
First I have examined the voltage loop, I found it to be composed of R6 and R8. This voltage divider sets the output voltage for the circuit.

When I come to the current loop, many questions arised:

I understand that the PNP transistor used in paralell with the internal pass element of LM350 to share the output current since LM350 cannot supply 5A. But how does the circuit work in the current loop configuration, I did not get it because:
To control the output current, we usually measure it by means of a sense resistor (shunt resistor). R3 may play that role, but I think only the current supplied by PNP transistor will be monitored by that.
If we assume the OPAMP LM301A is used to monitor the current, how does it regulate the current? What is the purpose to put it in an integrator form by placing C5 between its inverting input and its output!
What is the role of D1 and D2?


texts: Using cat5 and mic cables within same DMX512 universe

texts:
I understand that I'm not suposed to use mic cable for DMX sygnal. And that's the reason why the standard mandates 5-pin XLR connectors.
I also know that in practice 20 out of 20 events I've witnessed here in Ukraine used mic cables, and all the gear had 3-pin XLR for DMX.
I currently own an installation of DMX console and 8 PARs, connected with 1*6 + 7*3 meters of mic cable with 3-pin XLR connectors.
It works seamlessly, no visible glitches whatsoever.

My question is purely practical:
I want to connect another piece of equipment at 5 meters from the end of the aforementioned sequence of PARs. And I want to do it with Cat5 cable, as it's both cheaper and more appropriate as per standard.

Would it work? Or would it work better/more reliable if I use mic cable for the extension?


texts:
Question

Is there a maximum limit to mains frequency range that appliances will accept (e.g. if they conform to UK or EU standards?)

e.g. The Dynamic Demand web site indicates that there is a legal limit of about 49.5 Hz to 50.75 Hz (lines on the meter).

Why?

I'm configuring an Amber Switch (CAS-I-B) to turn on/off a hot water if the mains frequency is increased/decreased respectively, which in turn is performed by the inverter if the batteries are fully charged.

Note: the inverter is powered by a DC solar/battery system (no grid tie).

I'd like to increase the frequency to 53.5 Hz or even higher, but before doing that, wanted to know what the official limits are.  Obviously individual appliances may be higher, as they could be manufactured to operate in countries with lower quality power.  What kind of appliances should look out for in particular that are likely to be a constraint?

My guess is that AC motors are the most likely culprit as the higher frequency may make them run faster, so around the house that would be water pumps, refigerators and plug-in vacuum cleaners.

What is the most likely 'damage to equipment' one would see with wildly varying mains frequencies?


texts: Energy dissipation in a circuit with only capacitors

texts:
Context:
Consider a circuit with only two linear time invariant capacitors. If I charge one the capacitors and then throw a switch that closes the circuit, there will be some redistribution of charge. The capacitors are ideal and there is no resistance in the circuit.

Problem

I calculated the energy before the circuit was closed and after the circuit attained a steady state. There was some energy dissipation.

My question is: In what form is the dissipated energy leaving the circuit?


texts:
I have a question about the following LED drivers:

FAN5331, datasheet http://www.mouser.com/ds/2/149/FAN5331-92198.pdf

FAN5333, datasheet https://www.onsemi.com/pub/Collateral/FAN5333B-D.pdf

They look very similar apart from the output voltage, which is about 20V for 5331 and 30V for 5333.
From 5333 datasheet I can see that the SHDN pin can be used for PWM dimming control, but there is no such information in 5331 datasheet.

Can I still use FAN5331 with an external PWM signal, similar to FAN5333 ?


texts: How determinate parameters for thermal-model battery (Advanced question about battery modelling)

texts:
I'm trying to simulate an electrical model based on Ceraolo battery model for lead-acid battery. The challenge in this model is to determine the parameters that describe it.

I can understand and estimate most of the parameters. However, it is still unclear to me how the parameters \$Ke\$ described in the paper.

The problem in this case is that the equation used to define \$Ke\$ uses the value of \$Em\$ which is not a value obtained via lab tests.

For those who know and understand the model, it is known that \$Em\$ is the voltage source responsible for emf at the "beginning" of the circuit in question, while Figure 4 represents the voltage at the battery terminals (i.e at the "end" of the circuit). It is for this reason that I believe that it is not possible to use the test values to set the \$Em\$, since the test values already show the terminal voltage of the battery.

The equation I'm talking about:

\$E_m=E_{m0}-K_E(273+\theta)(1-SOC)\$

Figure 4

The table with the voltage values corresponding to Figure 4

\begin{array}{|c|c|c|c|c|c|c|c|c|c|}
\hline
Battery & V_0[V] & V_1[V] & V_2[V] & V_3[V] & V_4[V] & \theta_{end} & I[A] & t[h] \\ \hline
Battery\ 1  & 2.165 & 1.965 & 2.06 & 1.790 & 1.890 & 26 & 58 & 8.494\\ \hline
Battery\ 2 & 2.115 & 1.995 & 2.01 & 1.788 & 1.905 & 26 & 63 & 7.197\\ \hline
\end{array}

The parameters that Ceraolo obtained from these data were

\begin{array}{|c|c|c|}
\hline
Battery & E_{m0}[V] & K_E[mV/°C]  \\ \hline
Battery\ 1  & 2.165 & 0.782 \\ \hline
Battery\ 2 & 2.115 & 0.832 \\ \hline
\end{array}

It is easy to realize that the value of \$E_{m0}\$ can be obtained directly from the tests, but for those who will have patience, how will I get the value of \$Ke\$ if it is not possible to get \$E_m\$ through test labs ?

I think I have provided all the necessary information for the doubt. If you need anything else please let me know.
The article is attached at the beginning of the post.


texts: What is the name of a footprint that is designed to let you cut the trace between two nets?

texts:
I am designing a board where I want to have the ability to separate the connection between two power net's by cutting a trace. Originally headers were meant to be used but due to size constrains I decided to go with this instead.

Googling terms like "PCB break trace footprint" and whatnot doesn't give much since it's mostly about how to fix those traces. So, what is the name of a footprint like this and where can I find more info on it? For example, recommended trace width, pad size, etc.

So far I have something like this where I can cut the two 6 mil traces, make a solder bridge if I need, and via's for if I need to solder wires with more rigidity than just relying on them being attached to the pads using solder.


texts:
I am trying to understand the basic Sense Monitoring - High Side or Low Side wich is better and why? and does this also apply for AC voltage.

For example i insert Shunt resistor on phase line to the device.

So  in this picture i measure current on high-end?


texts:
I am making an Arduino VU meter. I need to convert an analog AC audio signal to a varying positive DC signal. I would like the following outputs:

2.5 V output at 0 V input (from VM1);
5 V at maximum output (when VM1 is 0.25V);
0 V at minimum output (when VM1 is -0.25V)
The output voltage varies between 0V and 5V DC based on the analog voltage from VM1

I found a circuit online that's meant for a 6V (peak-peak) signal:

My input (\$V_{m1}\$) is going to be around 0.25 V (peak-peak) coming from a 3.5mm jack. How can I adapt this circuit for my signal?


texts: Keep ESP32 non-RTC GPIO pin state HIGH in deep sleep

texts:
I'm trying to solve this in firmware before I move on to a hardware solution. I've got custom PCBs and I don't want to resolder / reorder them just yet, if I don't have to. Just like this guy [1]
I'm using Arduino IDE for ESP32, and I'm trying to keep a pin's state held (HIGH, in my case), during deep sleep.
I have GPIO16, GPIO17, GPIO18 (which I believe are all non-RTC GPIO pins). They're connected to three P-channel MOSFETs, which power an RGB LED. So my three pins need to be held HIGH while sleeping.
When my ESP32 goes into deep sleep, the RGB LED slowly fades up to full white brightness  Perhaps the slow transition is caused by each pin draining from HIGH to LOW?
After searching around, the method posted elsewhere doesn't work as expected. I've tried the below, but no luck.
Arduino IDE:
gpio_hold_en((gpio_num_t) 16);
gpio_hold_en((gpio_num_t) 17);
gpio_hold_en((gpio_num_t) 18);
gpio_deep_sleep_hold_en();
delay(10000);
esp_deep_sleep_start();

Strangely though, now the blue LED (on GPIO 18) doesn't come on, just the other two (16 and 17) snap to full brightness as soon as I call deep sleep. I think this means that they're going to GND right away.
Is it possible to hold these non-RTC GPIO pins HIGH during deep sleep? I've also tried to set them to be INPUT_PULLUP but no luck either.
Should I just bite the bullet and migrate all the code from Arduino IDE to IDF? Or has someone got this working with Arduino IDE?
The components are SMD soldered on to custom PCBs so I'm trying to solve this in software, before I consider swapping for N-Channel MOSFETs, adding external pull-up resistors, or just making new boards entirely.
Would love to hear if someone else has achieved this.
[1] ESP32: how to keep a pin high during deep sleep (RTC GPIO pull-ups are too weak)?


texts: Do high impedance pins have input capacitance?

texts:
I come from a software background and I'm trying to implement a simple counting circuit.  I am using this SN74LV8154 binary counter in a circuit which allows the outputs to be set to high impedance.

The design will have 4 counters connected together with the outputs all disabled and set to high impedance while counting.  After a short period of time, the clock input will be stopped and the count value from each counter will be read by enabling the outputs of each chip in turn.

I am concerned about the maximum count frequency in regards to load capacitance and asked this question which really cleared up what load capacitance is.

My question is: If the outputs of all counters are tied together while counting but all set to high impedance, does this mean the load capacitance of each counter while counting will be zero?

The counter specifies an output capacitance (Co) but only for loads with GND or VCC.  As I understand high impedance, outputs are very very high impedance but not a true open circuit so wouldn't they provide a small input capacitance too?  As the outputs will be tied together 4x8=32 shared tracks per chip, even with a small input capacitance, I am worried this will significantly change the switching characteristics of the counter.


texts: Quadrature counter on FPGA is running away

texts:
I am attempting to count pulses from a quadrature encoder in an Altera FPGA. I believe I have my counter set up correctly (circuit diagram below, following this tutorial), but when I turn my encoder on, the count just starts increasing non-stop. When I turn the encoder one way, the count speeds up, and when I turn it the other way it slows down, so it appears that I am in fact counting pulses, but also just counting up. Does anybody know why this might be?

simulate this circuit – Schematic created using CircuitLab

The count clock and count direction signals are going in to a 32-bit built-in counter function (LPM_COUNTER) on my Altera FPGA programmed using Quartus II v9.0. The output of this counter is stored in a buffer (LPM_BUSTRI) and read using a LabVIEW program whenever the LabVIEW code needs it. I have a similar LabVIEW code reading other buffers from the FPGA that is working fine, so I am fairly certain that the problem lies in my FPGA somewhere.

Your help is greatly appreciated!

EDIT: Corrected the displayed clock frequency.


texts:
I am designing a high frequency passive RFID tag-like device that receiving 27MHz wireless power, use it to power a onboard MCU and a low power transmitter. The estimated current drain is about 50mA. You may say this is a huge amount power for a passive RFID tag, moreover, the distance between the reader and tag will be 46cm maximum. However, in our application, we will have a powerful(25W) reader for this application.
My specific question here is about the power receiver. I have two available options. First one use diode and capacitor for a voltage multiplier, which is very common seen on RFID article, then follow by overvoltage protection and linear regulator, like this in following picture:

Comments:

Because of the high frequency of incoming power, I can use rather small(100nF) capacitor in voltage multiplier.
I add an overvoltage protection on linear regulator input(LT3065's Vin max up to 45V) for situation where the tag is occasionally brought too close to reader. M1 will start to draw excessive current when LT3065's input larger than about 20V.
I will use schottky diode whose trr<<40nS for this 27MHz input power.
I don't know how to deal with the transmitter and receiver coil, so I just left the receiver coil to a sine signal with a roughly(guess) amplitude. How can I model its parameter, like Rser? I noted the output of voltage multiplier depends on it.

So, will this circuit work?

********updated on 2.13:

I found a signal generator with maximum 1W output power to simulate the transmitter. For convenience and test purpose, I used a NFC antenna transmitter coil(2.1uH at 13.56MHz) at hand with the signal frequency changed to 13.56MHz. For maximum transmitting current, I add a capacitor(actually three, according to this app note by Atmel, for better trimming) serial with the transmitter coil for serial resonance at 13.56MHz. So the transmitter circuit just looks like below. Because the signal generator's output impedance is 50Ohm, and ought to be used with 50Ohm load. 100mW output power means about 6.3V amplitude on sine wave voltage source(Am I right?). So I will get about 120mA(I actual measured about 100mA with a serial 5Ohm resistor with oscilloscope) transmit coil current for the transmitter. Is this approach for optimal(longest) operating distance right? Should I use a power amplifier whose output impedance is much smaller instead of 50Ohm for a larger transmitter coil current?


texts: How do you wire a CPU fan to an external 12v PSU

texts:
I have a CPU fan that I'd like to wire to a 12v PSU.

I have tried following the advice here and here, and connected the black outside wire on the fan to my PSU -V, and then connected the next, red wire on the fan to my PSU +V.  Yellow and green wires are left disconnected; I want the fan to run at full speed.  The fan powers up just fine in this configuration, but spins in the wrong direction (it blows air down).

I'm using this little project as a learning tool to understand basic electrical theory.  My simplistic guess was that I had the wires backwards, so I switched the red and black fan wires (black to +V and red to -V).  When I turned the system back on the fan didn't start up at all.  I tried cutting and restripping the wires and then switched them back and forth a bit to make sure I didn't just have a bad connection, but it works every time in configuration 1 and never in configuration 2.  I'm a little confused as to why.

Why is this fan spinning backwards, and how do I wire this CPU fan so that it spins in the right direction?


texts: Charge, Voltage, or Current? What can be measured with the highest SNR?

texts: Suppose I have a Faraday cup and a certain number of ions hit the detector.  What is the highest signal to noise ratio way / circuit to measure this... does one measure the charge (coulombmeter), voltage (voltmeter), or current (ammeter)?  Is there a practical reason one is better than the others?  Does the choice depend on bandwidth?  Does the choice depend on total number of ions?


texts: What is the proper name for 'audio codec' ?

texts: Is there any formal name for audio codecs? My lecturer said today that audio codec is a jargon and I should not use these words in my diploma, unfortunately she did not tell me if there is a proper name. I was surprised because it is so widely used in datasheets.


texts: Cycle-Time/Latency optimization in synthesis of digital circuit question

texts:
I've been trying to build a solid understanding of digital synthesis. And I've found a useful book (this one) for it, specifically I'm into "Architectural optimization" now (section 4.5). In such section it is explained the trade-off among Area/Latency/Cycle time, the explanation is then divided in three subsections: Area/Latency; Cycle-time/Latency; Cycle-Time/Area. Basically it is consider the relationship between the two variable assuming the third is fixed.

I have trouble understanding a the Cycle-time/latency tradeoff here it is what the book reports:

  We consider bound sequencing graphs that are either representative of
  initial circuit specifications or derived by binding. Let us consider
  resource-dominated circuits first. For each value of the cycle-time of
  interest, the corresponding execution delays of the operations can be
  derived and a minimum-latency schedule computed. Alternatively,
  scheduling with chaining can be performed by considering the
  propagation delays of the resources. Let us consider now the case in
  which we are interested in the minimum cycletime compatible with a
  given latency. When the resources are combinational in nature, the
  problem reduces to determining the register boundaries that optimize
  the cycletime. This problem has been referred to as retiming, and it
  is dealt with in Section 9.3.1. The formulation and its solution can
  be extended to cope with sequential resources by modeling them as
  interconnections of a combinational component and register. These
  considerations can be applied to general circuits when the binding of
  the multiplexers and registers is specified and fixed and when the
  wiring and control-unit area and delay can be approximated as constant
  or neglected. Under these assumptions the overall area is constant.
  Then, the multiplexers can be considered as additional  combinational
  resources with their appropriate delays. The cycle-timet/latency
  trade-off points can he determined again by scheduling with chaining
  or retiming.

I don't really understand why there's the need for to study the tradeoff cycle time/latency, I'll try to highlight what I don't understand:

  For each value of the cycle-time of
  interest, the corresponding execution delays of the operations can be
  derived and a minimum-latency schedule computed.

It sounds like in this sentence that the cycle time can some how affect the resource scheduling and I don't understand why... If define time labels, these are independent from the cycle time and then I can perform resource scheduling anyway, since it is cycle-time independent I assume a minimum latency schedule is the same whatever the cycle-time actually is.

  Let us consider now the case in
  which we are interested in the minimum cycletime compatible with a
  given latency

Again here, I don't get the relations that there's between cycle-time and latency, especially I don't get the "compatible". The cycle time cannot be longer than the latency, but for a given schedule the cycle-time should be easy to derive.

I believe if I understand what the actual point is in the sentences I pointed out the rest should be easy to understand.


texts: IC Supply Current vs Temperature at low temperature

texts:
Background

I am designing a low power device where every uA counts. It has a temperature range from -25C - 35C.

In the datasheet for the 74AHC1G66; 74AHCT1G66, an analog switch I'm looking at, on page 4 it gives maximum supply current vs. temperature:

1 μA at 25°C
10 μA from -40°C - 85°C

Question

I can 'afford' 1 or 2 μA, but not 10. So, my question is: in a CMOS IC will supply current typically decrease with decreasing temperature? Even though the datasheet says at -40°C it could be up to 10 μA, will it most likely be under 1 μA?

I tried to research the answer to this. I found that for NMOS transistors iD is a function of temperature, from Wikipedia and Microelectronic Circuits Sedra and Smith. Contact potential increases with increasing temperature:

Vtn decreases with increasing contact potential:

iD increases as vT decreases:

Overall, this means iD increases with increasing temperature. Is this analysis on the right track? Or does it miss a lot of factors, for example, I think leakage is also a function of temperature.


texts: How does reading from a peripheral device at a specific address using SPI work?

texts:
This question is about trying to understand how the communication is implemented on a typical peripheral device such as an accelerometer, or flash chip.
More specifically, I'd like to understand how a peripheral device is able to start shifting out data from the correct address immediately after receiving that same address without any handshaking/clock-stretching required.
For example, this is the SPI-read timing diagram from an FRAM device. It shows the requested data being sent by the peripheral the very next clock after the address is received.

Bonus: What prompted this question is wanting to emulate this behavior for comms between two MCUs. For example, the main MCU would be able to read from the peripheral MCU at different addresses and the peripheral would be able to send data from one of multiple buffers via DMA transfer. The idea behind it is to enable multiple, high-throughput data streams between the devices with minimal overhead of handshaking.


texts:
I have a question regarding how diode clamps work in a ideal circuit.

The voltage source with infinite output impedance will force Vout to 6V
The diode will be forward biased with a vf of 0.6V. Thus clamping Vout to 5.6V

Is my issue that I am taking a non ideal model of the diode with a Vf of 0.6V while taking a fully ideal model of a voltage source with no output impedance to separate the two nets ?


texts: VHDL - need to understand output of simple math

texts:
Im new to VHDL, so my apologies if this question doesnt fit this forum. Here goes:

I have the following variables:

...
variable distanceToLight : integer;
variable lightLevel : integer;
...

I have a bug vhdl-file with lots of logic, and I have boiled my issues down to the following section:

...
if(lightLevel >= 0 and lightLevel <= 255)
then
    lightLevel := lightLevel*100/255;
    if(lightLevel >= 0 and lightLevel <= 255)
    then
        currentColor := (lightLevel,lightLevel,lightLevel);
    elsif (lightLevel < 0)
    then
        currentColor := PURPLE;
    else
        currentColor := YELLOW;
    end if;
else
    currentColor := RED; -- sanity testing that this is not hit
end if;
...

I have som logic that renders all pixels on the screen according this this function, sequentially, a single pixel at a time.

I experience, that lots of the outputs are actually YELLOW. Not all, but the far majority is. non is purple. This means that lightLevel  ends up as a value higher then 255.

The case is:
A) if lightLevel is between 0 and 255. Then lightLevel *100/255 can never be outside the range 0 to 255 either, e.g. should never be higher than the initial value if lightLevel.

So, logically this should never happen. So I need inputs to if i am using too complex math for the function to be syntesized? Or if I have mistaken the behaviour of integers and its range of values?

Another ting is: Some values seem to be constantly inside 0 and 255, some constantly above 255 and then there is som flickering on some of the pixels indicating that the same input values (x and y) gives varying output for each calculation.

Lots of complex calculations have been going in above this section, so could it be that there is an upper limit to the complexity of calculations possible to be syntesized?

I have been looking at this code for days now, almost going crazy :)

I use Quartus Prime Lite version 18.1 and I deploy to a De10-nano.