texts: Problems controlling an LM317 with an op-amp

texts:
I have the following circuit, part of my LM317 digitally adjustable power supply.

The problem that I have is correctly controlling the LM317 at U2: if I pull it's adjust pin to the ground, the output will go to 1.25 V. So far so good.

The problem comes when I connect the output of the opamp to the adjust pin, as in the schematics. For some reason when the output of the op-amp goes below 0.76V the output of the LM317 regulator will stay at 2.06V, even if the op-amp goes to 0V.

When the op-amp goes above 0.76V, the output of the LM317 is as expected.

So, why the op-amp does not sink the adjust pin correctly bellow 0.74V ? Am I missing something?

Thank you!


texts: Complex impedance calculation for resistors and coil

texts:
I have this circuit and I need to calculate the total complex impedance.

Note: the \$r\$ is internal resistance of the coil so how can we calculate the complex impedance?
The coil and the resistance \$R\$ are in parallel.


texts: Power supply - Boost voltage over distances

texts:
I'm looking for a good power supply design to boost the DC voltage and convert it to AC so it can be transported over a long distances with low loss. I have drawed a example picture:

The only thing that I know at the moment is that the two batteries are delivering 24VDC, and the load needs 9VDC and draws 3.8A. I just discovered that I have drawn to small fuse on the 24VDC side (1A).

I'm free to choose both frequency and the voltage on the AC, my only goal is to deliver 3.8A@9VDC to the load over a distance up to 300 meters with smallest possible loss.

So the questions are:
- What frequency should I choose? I have read that higher frequency is equal to smaller devices?
- What voltage should I choose?
- Which power supply design should I use? I have looked at Boost-buck designs, but they do not provide isolation. I have also looked at flyback supplies.


texts: Kirchoffs Laws and Class-A Amplifier Circuit

texts:
I have been attemtping to use Kirchoffs laws to solve a Class A amplifier circuit containing a single transistor.
I made several attempts at this trying slightly different approaches. I summarized the last attempt I made in a document, with some diagrams, which I will append to this question.
I got to a point where I had all the quantities I wanted in a single equation, with one additional quantity which I did not want (an unknown). This was i_B.
I ended up with this
$$V_{CC}=V_{CE}+\left(-(1+\beta)R_E-\beta R_C\right)i_B$$
I couldn't figure out how to proceed from here. Unless I made a mistake or otherwise missed something, I have used all the possible node/loop equations, some of which I found were not independent.
Possibly I missed a loop equation which is independent of the others or made some other error.
It must surely be possible to solve this system using Kirchoffs laws (plus one additional equation for the base-current to collector-current equation, aka transistor hfe).
Since writing this document I realized that there are a total of 7 possible loops with this circuit, 4 of which can be created from superpositions of the 3 minor loops. The minor loops are created by drawing "the most simple possible square loops on Figure 1/2/3".
I realized I could choose any path through the system to create a voltage loop equation from the parts of the system I am interested in.
Therefore I can do
$$V_{CC}=i_CR_C+V_{CE}-V_{BE}+i_2R_2$$
which picks up all the things I want: V_CC, V_CE, V_BE, but picks up additonal terms i_2 and i_C which I then don't have any equations which I can use to substitute for these terms without bringing in additional unwanted terms.
For example, Node 4 could be used to substitute for i_2, but this brings in i_CC and i_E. If I try to substitute for those things seem to just go in circles without progress.


texts: Reviewing an AC dimmer - trying to understand

texts:
I'm apology if the title is kinda generic but I found a (on a AC) which use IC and a triac and there is some points I don't really get.

Image from this application note:

Datasheet used as reference.

About the PTA0 pin :

How can the pin accept 120v since the range of the ADC is VSS to VDD (Page 161).
The maximum absolute voltage for input is VSS-0.3 to VDD+0.3 which is far away from 120v, (Page 149)
What about -120v? The PTA0 shouldn't have a diode to be a voltage above 0v?
Why using resistors for the zero-crossing on the PTA0 pin? If it is to limit the current I tought input pin handled them.

Z1 shouldn't do a shortcut when it reach the breakdown voltage from C1 to Ground? (C1 -> D2 -> Z1) (I assume the top graph is the positive side)

I'm trying to know why it need 0.5W, I don't think it may be the IC (25mA maximum for PTA* pins, but I don't find the power consuption overall (50mA could be the overall consuptions (including PTA* output pin I hope) ?)

Also, there is an exemple using a generic opto coupler where they connect the anode to a 100k which then go to the AC :

I know LED work with current instead of voltage... but i'm kinda surprise they work at 120v. Is it really possible or this is only true for opto coupler?
Should -120v destroy the led since it is much more higher than the regular 5v reverse input voltage?

Thanks


texts: DC/DC converter inductor makes annoying buzzing sound

texts:
I am using a PT4110E DC/DC converter to drive an LCD backlight. It operates at a frequency of 1.2 MHz.
Electrically, everything is working fine. Voltages are stable and the inductor isn't heating.
However, the inductor is making a loud annoying buzzing sound. How can I get rid of this sound? Is it possible to filter this sound out using maybe an RC filter? If yes, where do I add the filter?


texts:
I would like to replace the tda2822m stereo amplifier on a music keyboard because it fried. Problem is I'm not sure which one to use. Some kind of reference is written on the component: wx14a08y. I don't know what it means exactly. I keep finding amplifiers with other references, but I'm not sure they will work. How could I find out?

Here a picture of the PCB with the fried amplifier:


texts:
Is this the correct way to wire a rocker switch to LED strip?

simulate this circuit – Schematic created using CircuitLab

A lot of what I see online is people showing SPST 3-terminal switches for this application. Can I just use a 2-terminal like the one shown in the diagram?


texts: Help request to identify soldering station

texts:
I acquired this soldering station which does not have the manufacturer or model number on it. If someone could help to identify it, I would be very grateful.

Thank you,

Tom


texts:
Good afternoon all,

For the past several months I have been working on a project at work and the wire I am using is amazing.  When I go to solder it into a joint, the insulation does not shrink and run up the wire.  I LOVE this wire.

Several of the wire rolls that I am using are quickly becoming empty and I need to replace the wire.  So, I go to my friendly neighborhood electronics supplier and start looking at all the wire. I get what I thought would be the perfect replacement.  I succeeded in getting a heat-resistant insulation, but I failed in getting a nickle plated copper wire.  I cannot solder this stuff for nothing.

So, I am back to needing wire and wondering what to order.  Can someone provide some guidance at least on what insulation to choose?

Thanks in advance.


texts: is is possible to drop voltage without knowing a components amperage

texts:
I am new to circuits/electrical stuff
Correct me if i am wrong.
if i have an led (2.1V / 0.02A) and if i give it 0.02A it will only take 2.1V or if i give it 2.1V it will take 0.02A
Ohms law (\$I=\frac{V}{R}\$).
If start with 9V i can use ohms law to get the correct power for the led because i know how many amps it requires
My question is:
If i started with 9V. Could i drop the voltage down for a component that takes 5V without knowing how many amps it uses?
Sub-question:

Wouldn't a circuit like this drain a battery or cause the circuit to short out?


texts: Moving PIR sensor (or IR camera), aka Predator like alien scanner

texts:
To avoid public transport and the car, I decided to go to work on foot everyday but I have to pass a small, but dark (in the evening) and scaring wood.

Even if I use flashlights, I'd like to have a kind a "life scanner", like the one used by Predator vs Alien to detect alive (hot/moving) creatures.

Beside the sci fiction side of the question, I was wondering if PIR can be used while moving, so that I can mount on my backpack and control it with an arduino while I'm walking.

If it's not possible, do you have any other ideas?

What I need it's just a way to know if there are alive, enough big to be scaring, creatures in the wilderness around me (for not alive creatures we will discuss later).

Edit

Has pointed out, a good alternative can be an Infrared camera, there are some good tutorial and Howtos in the Net.

I don't need a detailed image, but just to know if and (more or less) where there are alive creatures (hot blood animals?), as an image sometime is better then 1000 words:

Edit 2

As it has been pointed out, is this feasible or it's just sci-fiction?

Thermographic cameras exists and are widely used: http://en.wikipedia.org/wiki/Thermographic_camera

I found a solution here http://www.embedds.com/interactive-diy-infrared-and-ultrasonic-scanner/ , but the range is really small (21 inches = 0.5 meters)

Edit 3

This is another way to create a "radar" starting from a home made thermographic camera.

http://hackaday.com/2009/07/01/poor-mans-thermographic-camera/


texts: Is there a Quartus Signal Tap II equivalent for the Microsemi Libero SoC?

texts: Quartus Signal Tap is extremely beneficial in debugging complex problems. However, there is no such toolset in the Microsemi Libero SmartDebug toolset. I would expect that Microsemi does provide capability to create an internal logic analyzer by using the device resources but don't know how it can be done. Any ideas?


texts: Input voltage control by resistor, is this method is correct or not?

texts:
In my application I have a requirement to switch 40V to 5V with the help of a linear voltage regulator. My load circuit consumes approx 7 to 8 mA.
Due to the unavailability of any specific model of a linear voltage regulator, I am using 7805 for this purpose. But the input voltage limit of 7805 is 35V.
I already tried a voltage divider method put before 7805 to control the input voltage level, but that method has other issues because of the internal resistance of the 7805.
Here I applied one input resistor to control input voltage flow.
Circuit:

Now due to 7mA of load, and (2.2Kohm, 1-watt) resistor, the voltage drop of the resistor is (7/1000)*2200 = 15.4V.
The input voltage of 7805 is ( 40 - 15.4 ) = 24.6 V in this scenario which is less than the safe limit of 7805.
Is this solution is suitable for this type of application, or there is another efficient way to solve this kind of thing?


texts: Switch is open in this circuit. How do I know that current IL (inductor) is 0 and voltage(Uc) of capacitor is 0 when the switch is open(t<0)? Can someone explain me this as simple as possible.


texts: Multiple AC-DC power supplies or use DC-DC converters and one power supply?

texts: I have an electrical control box that needs 48v, 12v, and 5v to power stepper motors, sensors, and microcontrollers, respecitvely. All power items will be mounted on a DIN rail right next to each other. Is it better to have an AC-DC power supply for each output voltage, or one larger 48v supply and use DC-DC converters to get the lower voltages needed? It's cheaper to get seperate power supplies, so if there aren't going to be any negative effects I'd like to go that route. Thanks!


texts: Mini 360 buck converter: 5v to 3.6v possible?

texts:
I am new to electronics and for my first project, I am using an esp8266 12 e WiFi chip to put together an air sensor web server. My breadboard prototype works but I want to add some other sensors which require 5v. So I need to power the chip at 3.6v and some of the sensors at 5v.
I am planning on getting a power adapter plugged into mains and then a buck converter or 2 to get the required voltages. If I get a 9v power adapter, I need 2 buck converters. If I get a 5v power adapter, I only need 1 buck converter. However, I am aware that there are minimum voltage differences between the input and output voltages so am not sure if this will work, given that 5v is kinda close to 3.6v.

I found this pdf which seems to address this question. However my inexperience is making this difficult. Can someone with more experience either 1) tell me if the voltage difference is big enough, or preferably, 2) walk me through the maths in the pdf to arrive at a conclusion?


texts:
I was hoping someone would be able to have a look at a schematic for a split keyboard I've been working on. I know there are quite a few designs online but most of them are using a processor on a breakout board and I would like to have the chip directly on the PCB. I wanted to be sure I have the bypass capacitors done correctly. Any advice would be appreciated.  Thank you

Hi-Res Schematic

******************SOLVED FOR NOW******************

I appreciate the help, thank you. That should give me plenty of homework. I will re-post the schematic when I take care of those issues.

******************CAPACITOR SIZING & PLACEMENT******************

I've been looking through the 32u4 datasheet for clarification and they suggested a 10uF capacitor on the VBUS. I believe having extra capacitors would be fine but wanted to check. So far I was planning on the following:

VBUS [PIN 7 ]: 10uF, 1uF
VCC  [PIN 14]: 10uF(bulk?), 1uF
VCC  [PIN 34]: 100nF
UVCC [PIN 2 ]: 100nF
AVCC [PIN 24]: 100nF
AVCC [PIN 44]: 100nF


texts:
I am using an SPI peripheral in my application. The peripheral returns packets containing 15 data bits, plus an Even Parity bit for error detection.

Therefore all zeros, and all ones both pass the parity check.

This means that my microcontroller cannot detect the most common type of error: the peripheral being disconnected!  In this case, the received bits are all zero, which passes the parity check.

Presuming that it would have been just as easy for the manufacturer of the peripheral to implement Odd parity, my question is:  Why would they have chosen to use even parity in this case?  Is there some other advantage of Even Parity in this case to make up for the fact that it's unable to catch the most common type of error?


texts:
I have a little problem using GSM SIM900 module connected to the Arduino the call is working alright but it doesn't send me SMS I don't know why. This is my code:

#include <SoftwareSerial.h>
SoftwareSerial SIM900(2, 3);

void setup()
{
  SIM900.begin(9600);
  SIM900power();
  delay(20000);  // give time to log on to network.
}

void SIM900power()
// software equivalent of pressing the GSM shield "power" button
{
  digitalWrite(9, HIGH);
  delay(1000);
  digitalWrite(9, LOW);
  delay(5000);
}

void sendSMS()
{
  SIM900.print("AT+CMGF=1\r");                                                        // AT command to send SMS message
  delay(100);
  SIM900.println("AT + CMGS = \"00201155706922"
  "");                                     // recipient's mobile number, in international format
  delay(100);
  SIM900.println("Hello, world. This is a text message from an Arduino Uno.");        // message to send
  delay(100);
  SIM900.println((char)26);                       // End AT command with a ^Z, ASCII code 26
  delay(100);
  SIM900.println();
  delay(5000);                                     // give module time to send SMS
  SIM900power();                                   // turn off module
}

void loop()
{
    sendSMS();
  do {} while (1);
}


texts: using pressure sensor with 0-10v output for 0-10bar using arduino but pressure value won't cross 4bar. so is a voltage divider required in this case?

texts: I have a pressure sensor working at 24V dc whose output is analog 0-10V for 0-10bar pressure. I am using this sensor with Arduino Uno. I know that the pressure value will never go beyond 4bar. So do I have to use a voltage divider in this case or not using it will still do the job?


texts: Active filter with series inductor and resistor - do these exist?

texts:
I have seen (online) and in books basic active filters (involving an op-amp) with a series R C branch at the input side. This series R C branch at the input side would make the circuit a high-pass filter. Series RC configuration at the input is quite commonly seen online. However, there appear to be no circuit diagrams seen online involving series R and L (resistor and inductor in series) for the input branch, as shown below in the drawing.

There is likely some reasons for no diagrams like this seen online - anywhere. I don't know those reasons, and definitely interested to know why. Anyone know why op-amp configurations with series RL inputs are not seen? Thanks in advance for any comments!


texts: I have tried to make a reaction timer using IC 4026. But due to unavailability of IC 4026 I want to replace it. Can I use 4017 instead of 4026?


texts: Extending battery life: Calculating advantage of adding more batteries

texts:
I have a small 3 volt device with an MCU and 8 LEDs that I'm currently powering by two AAA batteries connected in series. With fresh batteries, I start out with about 3.2-3.3 volts and get very good brightness on my LEDs, they're almost brighter than they need to be. However after a couple of months the brightness drops off significantly (the LEDs only blink for an hour or so each day).

I had an idea to add two extra AAA batteries, for a total of four batteries and a voltage of 6 volts (6.4 volts starting out with fresh batteries). I would then use these with a buck-boost converter set to an output voltage of 3 volts. There are two things I am however really unsure about:

How do I calculate the battery life of this new 6V/buck-boost combination? I am assuming that the device would continue to function even when all four batteries output well below 3 volts, but how low can it go and still power the device? I assume I can never get more than double the battery life of what I have now with my current 3V setup?
Am I overthinking this? Maybe adding the two extra AAA batteries in paralell would be better. Does anyone have any experience?


texts: Are there downsides to using resistors with too high power ratings?

texts:
I'm hoping to measure the current draw to my ESP8266 with a scope and a shunt resistor. I think a 1ohm resistor might drop the voltage too much, so I'm thinking to use a 0.5ohm (or even a 0.1ohm) instead.

However, most 0.5ohm (and 0.1ohm) resistors tend to have at least 1W, 2W power ratings.

Are there issues with using resistors that have power ratings much higher than required?


texts: Voltage drops not adding up - beginner question

texts:
I'm fairly new to electronics and playing around with a very simple series circuit - 2 resistors of ~220k Ohm and a 3v power supply, which I'm measuring with a digital multimeter.

If I measure the voltage across both resistors (or direct across the power supply terminals) I get a reading of 3.37 volts, but if I take a reading across the individual resistors I get 1.656 and 1.676 V (adding up to 3.332). I'm wondering what would account for the difference in total voltage? Even if the multimeter wasn't calibrated properly I'd expect it to be consistent?

Thanks!


texts: Help identify SMD diode without markings

texts: It is a diode but no marking at all, except the cathode band. Please help.


texts: Degenerated Differential Pair voltage headroom

texts:
I was reading about ways to make the differential gain linear by adding degenerative resistors Rs as shown, but it has voltage swing limitations, having swing reduced by Is*Rs( when one of the MOS reaches cutoff)

So there is another topology for swing limitation problem, which is

My question is how is the ss gain and swing different in this topology and how to analyze the large and ss model gain. How about power consumption?
My approach is-

first apply miller theorem, but I'm not sure how to break the 2Rs. Suppose we get Rs each side, so I have ss model where Rs and Rd (parallel with a near-infinite current source, Hence system has Av= Rd/Rs( CS degeneration case)
Now in large-signal, the output can go max Vcc and regarding min value, I believe it'll be (Vgs-Vt) + Vov(overdrive), around 0.25+0.25 = 0.5 V, but We have Rs as well, there will be some V drop across R(say 0.5V) hence, certainly Vs must be 0.5 volt, then net Vomin = 1V. I know I'm wrong, please help me regarding the large signal to get the intuitive idea.


texts:
This picture is taken from Computer Organization and Design, Fourth Edition, David A. Patterson, John L. Hennessy. Sorry for the low resolution.

I cannot get my head around it. I can see why the bits to the right become lsb's in the product (Product1, Product0), but then the same thing is done for bits to the left. What about carries? Try this for Mcand and Mplier equal to 2^31. Then the correct Product63 is 0 (because the correct result is 2^62), but this design would set Product63 to 1, which is wrong!

Is there some deep mathematical property that could rescue this design, or am I correct to think that we need progressively wider adders to the left, as we go down the levels?

Elaboration

To facilitate readers, I remind how we do pencil-and-paper multiplication (4 bit example).

            M3 M2 M1 M0 (Mcand)
          * m3 m2 m1 m0 (Mplier)
-----------------------
            a3 a2 a1 a0 (Mplier0*Mcand)
+        b3 b2 b1 b0    (Mplier1*Mcand)
+     c3 c2 c1 c0       (Mplier2*Mcand)
+  d3 d2 d1 d0          (Mplier3*Mcand)
-----------------------
p7 p6 p5 p4 p3 p2 p1 p0 (Product)


texts: Custom Libraries in Altium not showing components

texts:
After trying in vain to find a normal set of libraries for Altium 17 I decided to make my own custom library for a specific project. I created a new integrated library project in which I then created PCB and schematic libraries. After spending several hours learning how to and creating the footprints and symbols I have arrived a the point where I had several elements in the library.

I compiled the integrated library but when I tried to use my created symbols the library  displayed only one part (the one that was initially made) :

Even though, as of now I have three more parts in the same library project. I tried compiling and recompiling the library several times with no result. What am I doing wrong?


texts: Can I get a pair of schottky diodes in a single chip?

texts:
I'm building a motor driver circuit, and am looking at diodes to clamp the output voltage between the supply rails. Apparenly, I should use schottky diodes for this purpose.

My question is, are there ICs out there than contain a pair of diodes arranged as shown below?

┌───►|──┬──►|───┐
│       │       │
0V      S       V+

Or should I just buy a pair of single diodes?


texts: Solid State Relay replacement for SRD-12VDC-SL-C

texts:
I've bought a relay board controlled over modbus from ali that contains 16x SRD-12VDC-SL-C relays to control my heating cables on the floor using rpi and nodered, my question is can I find a SSR pin compatible replacement for those relays? (I only use the 'NO' pin so NC output is not mandatory)
After a couple of days of working I can see that I'll hit the 100k on/off cycles pretty fast, I want to have some information on what options do I have regarding potential fixes/replacements of those boards (besides replace to another SRD-12VDC-SL-C relay...)
Also if somebody have any other ideas I'll be happy to hear them out :)
EDIT
System is "fail safe" that is, any damage of relay will not cause damage to my heating cables, or house, or anything...
I do not use RPI GPIO to control the relays, I control the state or relays using modbus RTU protocol


texts:
In CMOS design, we always use two inverters as a buffer, but at some point, I dont quite understand the functions or importances of the buffer.

As I was told before, 1) the buffer could smooth the output, but why ? It is two inverters, for example, if I design a ring voltage oscillator consisting of many inversters, why do i still need two inverters to the output of the VCO ? How can this buffer to smooth the ouput of VCO.   2)  Also, the buffer usually can drive the big load (cap or res ), this is totally blurry for me, I dont understand it.

I just know these two buffer's function, and I even dont understand it why it has such functions, and for other use, I am not sure...

Hope get more help to understand this small but important block...


texts:
I have very little knowledge about power draw / conversions etc. I would like to power a Kinect v2 Sensor from a USB Power bank. I saw the USB C and QC3.0 on this powerbank has between 9 and 12V output. I have read although the Kinect sensor is 12V 2.67A it only draws 16w per hour according to this user. So I would like to know can I splice up a USB-C cable (using red & black wires) to a wire that connects to my Kinect to Windows Adapter Any advice would be great thanks.

The goal is to have a mobile scanner with at least 3 to 4 hours battery life.


texts: Differentiating between 32-QAM and 32-PSK

texts:
A communication channel with 4 kHz bandwidth requires 40 kbps data rate.
What is the most suitable modulation technique to use in this particular scenario?

for this I used the Nyquist theorem.
 C=2B log2 L

40*1000=2*4*1000*log2 L

L=2^5 = 32

Now my problem is what the correct modulation technique is. I searched over google and found that apart from 32QAM, 32PSK exists.

I'm new to this stuff so an input is highly appreciated. Thanks.


texts: How can I measure small scale movement with an electronic component?

texts:
I'm working on a project which involves measuring the distance between two pins which are nominally 3-5 cm apart.  These pins can move up to 1cm in either direction.  I need to take a measurement of the distance between the pins which is accurate to about 500 μm.

Currently we take a measurement once a day using calipers and record the distance manually, but I need to automate the process.

Update (2012-02-21)

Okay, I figured the implementation details were unimportant, but as a lot of people are asking for more detail, here goes.  We want to measure the opening and closing of a crack in a brick wall over the course of a year or more.  We currently drill holes and insert two metal pins into the wall either side of the crack and take measurements between the two pins.  So long as we can measure the opening and closing of the crack over time, then the implementation is unimportant.


texts:
sometime ago I built an emulator for the 8086 chip and now I'm wanting to actually own one and set one up for some bit banging and such. Note, I'm not interested in all the PC specifics(DMA, PIC, BIOS, etc) only the bare basics to get the 8086 to run some code, which as I understand only requires a power supply, oscillator/clock source, and some RAM(unknown which type?)

So, for the most part all of the components are easy to find except for the one I need: The 8086 processor itself. I've not been able to find anything but (very pricey) collector's items 8086 chips. So where can I find a reasonably priced replica 8086 chip? Note: The pin out doesn't need to be the exact same, but I'd prefer it to be DIP and expose all of the features of the 8086. Also, don't just say "try buying an old 486 computer" After the 8086, the x86 line of processors got insanely complex. For this reason, I'm sticking to just the 8086. Though possibly an 8186 would be OK.

Also, if there is a system-on-chip type 8086 setup, that'd be awesome. (Note, I'm just talking about a chip that includes the RAM  and possibly some flash ROM on it)


texts: grid dip AN/PRM10: Is the normal operating distance so small?

texts: I recently bought an AN/PRM-10 multifunction grid dip. After I replaced some electron tubes by new ones, most of the functions seem to work fine, but in the grid dip mode, I get no dip unless I place the coil very near to the resonant circuit to be tested (no more than 2-3 cm). My question for all the persons who are used with grid dips: is it the normal operating distance ? I thought the circuit would react even at 20 cm at least.


texts: Finding correct RC value for transient equations in DC RC circuit

texts:
simulate this circuit – Schematic created using CircuitLab
So I'm doing this problem in boylestad book. I need to find \$v_c\$ and \$i_c\$. I converted the current source to voltage source.
I found the voltage at the upper node including the capacitor is 3.27 V. So the $$v_c = 3.27(1-e^{-1/\tau})$$ The answer in the back of the book confirms this. Where I have an issue is with both the RC value and the current \$i_c\$.
For the \$\tau\$ I have supposed that the R value is seen from the branch in the capacitor, so
$$ \tau = \frac{(4460 \times6800)}{(4460+6800)}\times (0.000020) = 0.05386$$
however the book says it should be \$0.05380\$, so I'm not sure if I have done the right way here or the book has rounded down.
The answer in the book for \$i_c\$ is
$$i_c = 1.22mAe^{-t/53.80ms}$$
I got this correct through superposition except for the \$\tau\$. So really my only question is how would you work out \$\tau\$.


texts:
Now matter how many times I tried to do it again one of the output is always 0 and I don't know how to show it in gates. Is is possible or do I make any mistake?
The requirement are below:

The circuit should take 4-bit input and generate 3-bit output.
The input consists of two 2-bit binary numbers X(X1X0) and Y(Y1Y0), respectively.
The output is represented as O(O2O1O0).

The circuit is supposed to perform two basic operations based on the values of the X and Y :

If X and Y are both odd numbers then the circuit should add X and Y and set the output O as the result of the addition operation.
Otherwise, the system should multiply X and Y and set the output as the result of the multiplication.

Suppose the input is given as 1011. The left most two bits represents X in the form of X1X0 and the rightmost two bits represent Y as Y1Y0. Therefore, X = 10 and Y = 11. Since X is even and Y is an odd number, the numbers will be multiplied and the value of output, O, should be set to 110 (10*11 = 110).


texts: VHDL: how to take a character out of a string

texts:
I have an array of strings. A state machine is supposed to take one at a time, then push it to a FIFO character by character. The fifo is of an std_logic_vector(7 downto 0) type. What is the syntax to take a char out of the array of strings?

    type str is array(0 to 15) of character;
type message_reference_type is array(0 to 15) of str;
constant message_reference: message_reference_type :=

(
"ASPEED = ~",
"BSPEED = ~",
"~",
"~",
"~",
"~",
"~",
"~",
"~",
"~",
"~",
"~",
"~",
"~",
"~",
"~"
);

....

char_to_fifo <= std_logic_vector(to_unsigned((message_reference(current_message)(char_pushing)), 8));

The last line is wrong, but i can't seem to figure the right way


texts: At what acceleration will electron flow be disturbed?

texts:
Came across a question regarding max G force that electronics can withstand, and immediately wondered at what speed/force will the electron flow be disturbed, and/or stopped.

I might not be thinking right about this, but if for your opinion I do not understand it, please explain.


texts: So I need to find what will be the average of a flipped square wave. I know that the high amplitude is 15V and the low amplitude is -9V and the average of the original signal is 2V. What will be the average of the inverted square wave?


texts: Soft-power on/off with ATMega/Relay causes brown-outs and unexpected voltages

texts:
This questions consists of two parts.

Background

I'm designing a digitally controller class D amplifier. Main IC's are a TI TPA3116D2 Class D amplifier, a TI PGA2311 volume control and an ATMega328P (running at 5V with internal 8Mhz oscillator).

Problem 1: Brown out when relay engages

I power my board with 24VDC. For now that's coming from a lab power supply. U303 provides 5V for the MCU.

The MCU in turn, controls relay K301, which will be used to power the other IC's. 24VDC will go directly to the TPA3116D2. U304 regulates 5V for other digital parts that are normally off, like a display. U301 and U302 create ±5V for the analog part of the PGA2311.

When the relay activates, the 5V from U303 drops enough to reset the MCU.

Somehow U303 can't keep up with either (or both) increased current draw from the relay coil or drop in input voltage because the rest of the circuit is powering up.

Would adding bigger caps on the input/output of U303 (or a big buffer cap on the 24VDC input) resolve this issue?
Is there a better way than using a bulky relay? Worst case my system would need 4-5A if the amplifier is at full volume. Would it be better to use a MOSFET and gradually bring up VCC to 24VDC?
I notice that U303 gets quite hot (about 60°C) when the relay is active, this might also be a reason to switch to a MOSFET based setup (or use a bigger regulator).

Problem 2: An unexpected voltage

When powered off, there seems to be about 1.3V on the switched 5V rails.

My PCB is 4 layer. Top and bottom are for signals, the inner layers are GND and power (VCC in most places, ±5V in others).

I've split the GND into two planes (red outline). Left is for the input/digital parts, right is for the analog parts.

Could this problem occur because I leave the VCC power input floating when powered off?
What is a good solution for this? Connect VCC to GND with a resistor? Ideally I'd use the relay to switch between 24VDC and a resistor to GND, but I've designed the thing the wrong way around. :-(

Notes

For now, I've by-passed the relay and power the entire circuit directly - so no soft power on/off. The amp functions correctly then (except for some fine-tuning in the software for volume control, etc.)

This is a hobby project, the first one on this scale, so feel free to point out any other obvious mistakes.


texts:
I'm looking for a simple circuit, preferably based on the 555 in order to get continuous configurable fading tones (chimes), just like a "door open warning". It will fade in and fade out, not very annoying.

Example sound


texts: Is high temperatures breaking the circuit?

texts:
I was watching this video, where they were demonstrating the difference between breaking AC and DC current.

https://www.youtube.com/watch?v=Zez2r1RPpWY

When they try to break the DC current, an arc forms. It continues for a while, but then breaks.

Does it break because the material gets so hot, that the resistance increases and consequently reduces the voltage experienced over the gap, thus requiring the gap to be reduced to maintain the arc?

I've experienced a similar effect when I was arc welding. The material would get so hot that maintaining an arc was impossible. I didn't understand why until I saw this video.


texts:
I am building a small application, that should be able to connect over wifi to server, pull some data and turn a connected servo accord the result. The system should be powered on battery. Is this something ESP8266 WiFi module is capable of doing? I found this article, but I am confused, why is the module connected to the computer, is it just for programming purposes?

Thank you,
Martin.


texts: Am I using the right resistors with these MOSFETs for an ESP8266 controlled LED strip?

texts:
this is my first question here. I hope I don't mess it up.

I made a WiFi controlled LED strip about a year ago. The LED strip is one of the "dumb" (no individual pixel control) 12V ones and I used a Wemos Mini to control it. Now, I want to make a another one, but I can't remember why I chose the resistor values I did. Does the following look right?

The MOSFETs are 40T03GP. I tried googling, but I can't find a setup similar to mine to compare it to.


texts: eSIM/euicc IC - is it available and how does it work?

texts:
So, I cannot really wrap my head around this. I can see from phones that eSIM is becoming more and more common, however I am not completely sure how this works.
I wanted to find an eSIM IC ready to use, but I cannot seem to find one from the normal global distributors. To my understanding this is because eSIM is something typically provided together with an MNO or MVNO.
So due to the lack of a specific chip, I also have some trouble understanding how this technically works. I can image the IC most likely an MFF2 style IC, connects to the modem just like a standard simcard, but how does one program it?
Any help and explanation appreciated.
Thanks


texts: STM32 print via UART without Nucleo/Discovery

texts:
I would like for debugging/trace purposes to print texts (preferably via printf but just text is also fine) from an STM32F103C8T6 to a (PC) terminal application.

I noticed that all examples use a Nucleo or Discovery board but I don't have those.
I'm using ST Link/V2 and System Workbench (Eclipse).

Does anybody know how to do this or if it is even possible? (I guess so with some USB/RS232 converter maybe).


texts:
How should I proceed with the design of this RGB LED and what does this wiring diagram imply?

I haven't made a design with RGBs before, so the wiring diagram from the RGB Datasheet puzzles me. My immediate thoughts are as shown in the attached schematic.

Don't mind the transistor specs and resistor values (just needed the footprint) I would also like to implement a load switch between VCC and COM+ and some pulldowns for the transistors, depending on the MCU

(Wiring diagram)

(Schematic)


texts:
I`m new on it, consider it please. I have to build a 4-bit counter in 4221 bcd using D triggers. Learning about triggers, and seeking for completed schemes, I made the next one:

Took the classic binary counter(it's subtractive , but nevermind)

And put there code converter from bin to 4221-bcd, and got complete 4221 subtractive  counter.

I give it to my teacher, and She said, that

it should be initially in 4221 bcd, not binary+converter
I had to make a synchronous counter

My questions:

1) Is it possible to build a D-trigger based-only synchronous counter?

2) How do you, think, what did She mean, saying "initially in 4221, without converters"?


texts: What reasons are there to avoid vertical through-hole resistors?

texts:
I'm working on a layout for a PCB and I need to include a handful of pull-up resistors. The board I'm working on will be a proof of concept, and it is likely I will only need one (and order two). That being said, I'd like to keep the board area small. In addition, I'm using through-hole components to make any revisions easy.

For these pull-up resistors, vertically mounting them would save some space and cost instead of alternatively mounting them horizontally. However, I rarely see vertically mounted resistors in commercial or industrial products. So, should I avoid using the vertical resistors even though they will save cost up front?

Upon searching Google for an answer to my question, I came across these two links:
http://www.head-fi.org/t/162556/any-reason-why-i-shouldnt-use-resistors-vertically
http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=90

The consensus is that vertical resistors are less popular because:

Auto-insertion machines can't (or don't prefer) vertical resistors. This isn't an issue for me since I'll be soldering the board myself.
Horizontal mounting provides more stress relief. This is also no problem since my board will be safe in an enclosure that is only going to get light use to prove a concept.

Are there any other reasons I am overlooking? Granted, most modern designs use SMT components that take up even less space. If the best answer to my particular situation is to just break down and learn to solder the SMT components, I would still like the background knowledge as to why the horizontal resistors are more popular.


texts: How to measure SD card data timing vs. clock

texts:
I'm doing EVT testing of our product and I want to measure the SD card data vs. clock timing to make sure we're inside the specs. We're using LS1043A that boots Linux (via U-Boot) from an SD card using SDIO mode - not SPI.

I want to measure the timings on both sides: at CPU (SD → CPU) and at SD (CPU → SD), but I don't know the direction of data on the four data pins. E.g., when taking measurements at the SD side I have no idea whether I'm seeing data out (CPU reading) or data in (CPU writing) on the scope and I need to know because there are different setup and hold times for both. The CPU output also needs to be measured against the clock's falling edge according to the LS1043 datasheet.

See an example taken in U-Boot (green - clock, yellow - data2):

Another taken when already in Linux (green - clock, yellow - data2, blue - data3):

So how do I know the direction of data? Is there a command I can use to explicitly read/write from/to SD card? I found mmc write, would that work?


texts:
I am trying to reverse the polarity on a rather beefy motor (5 amp, 60v) in the most simple way possible.

I need to build an h-bridge just to reverse the current, I am controlling speed elsewhere. Can I simply wire up 2 N-Channel MOSFETs and 2 P-Channel MOSFETs into a IO pin from the MC (with resistors of course) or is it more complicated than that.

I see lots of schematics online that are different, some use diodes, some don't.

Any advice?


texts: What is a good way to connect a LED to a PCB?

texts:
I need to connect a 5mm LED to a PCB, but the LED is not supposed to be soldered directly to it, but rather connected using a wire.
I'm going to produce around 500 PCBs, so I need a way to connect them the fastest and more reliable way. Is there a standard way to do it?
The LED doesn't have to be a standard 5mm one. If there are other options I'm open to it


texts:
I need someone to revise/suggest improvement for the audio power amplifier I am designing. This PA is going to be used for driving the horn speaker (8ohm 100W). I decided to start design from scratch instead of just copy/paste existing design (of course this is still not something new, you can find the same topology on Internet, Hitachi has similar concept in app note). As you can see, it is composed of two stage differential amplifier. The first differential amplifier uses Wilson current mirror as a current source, and the second the "standard" current mirror as a load. The second differential amplifier provides bias voltage and drives the output stage. For the output stage, I selected mosfet approach that is composed of 4 mosfet transistors (complementary). I must emphasize that I am not much in analog design field, so does not have strong sense if this design is any good. This is the part of bigger project with the rest of digital logic. The main aims of this PA is to be stable, and to use in wide temperature range (preferably in range of -20°C - 75°C), if possible. Therefore, I need your revision and improvement suggestion. I highlighted a couple of design doubts:

I am not sure about this kind of bias (the red circled resistor would be potentiometer). Is this stable and safe (not get in situation to blow up mosfets while adjusting bias)?
Is this design stable (not oscillate)? Of course, I am planning to add Boucherot cell (Zobel network) at the output.
How to improve temperature operating range?

Please note that I used available bjt transistors from the LTspice lib. Maybe some improvement can be done also in that part.
The following are screenshots of schematic, transient analysis, and FFT analysis performed in LTspice.

EDIT: According to my simulations, I noticed that the mosfet bias current change with temperature is mostly caused due to change of emitter current of driving differential amplifier (that also changes the voltage drop on R4 and sets mosfet bias). I decided to implement current source based on current in emitter of the driving differential amplifier instead of simple resistor. I got better results in therm of bias stability, if I am correct. There are also some changes due to suggestions. The revised schematic is following:


texts: Common collector effect of emitter resistor on output impedance

texts:
I've been trying to figure out why the expression for output impedance in a common collector configuration contains a parallel Re emitter resistor.
Looking at the classic circuit, it looks as though the Re resistor is not part of the seen output impedance (similar to the way it isn't in a common emitter configuration)

I'm a rather elderly person who has decided to take on myself to self-study analog electronics - so I would appreciate if someone more experienced and knowledgeable could enlighten me about this issue.

Thanks,
   Sefer.


texts: What defines a source of power, the current or the voltage?

texts:
I have an apparently simple question, but I can't seem to figure it out.

I learned in school that the generators (source powers) are defined by their voltage, and that made a lot of sense to me. Afterall, we say 1.5v, 6v, 9v, batteries, right?

But I noticed that in my source (that converts from wall socket's 100-240V AC), it reads: Output: 5V, 1A. My question is, how can it possible have a constant voltage and current? That makes no sense!

That is, we have U = Ri, and R is fixed in the circuit (sum of the resistance of the wires and components), so the source has to specify either the voltage OR the intensity of the current, not both! The other value is calculated, given the resistance. So which one is it? And what does the other value in my source means? Is it the maximum voltage/current? That would make more sense.

Some Background:

My problem with this was that I was trying to make my Integrated Circuits Chips (SN74LS series) to work with this source, but I think they burned out, because they simple didn't work. I made I simple test with the NOT gate, and it did nothing. It's such a simple setup I think it's very likely it has burned out. The 1A really freaked me out when I read them (after testing), because I'm aware that the regular current in a circuit is around 20-50mA (way less). If the current specified is the maximum (as it was clear to me), it should have worked; if the current was fixed, and the voltage was the maximum, then it might had burnt out, as it did in reality - but that makes absolutely no sense to me. What I am missing?


texts: How is the signal assigned to a pin by default

texts:
Here's the simple verilog code that contains WR_n signal. This signal (net) is not explicitly assigned to a LOC (pin) in the .ucf file. The design implements without any errors. I would assume that the WR_n net is assigned automatically to a pin. How do I know which pin is that?

module BasicCounter(
input PCLK,
input RESET,
output reg WR_n,
output [31:0] DQ,
output [7:0] LED
);

reg [31:0] Counter;

// Put key signals on LEDs for DEBUG, ~ since LED is ON when signal is low
assign LED = ~Counter[31:24];
assign DQ = Counter;

always @ (posedge PCLK or posedge RESET) begin
if (RESET) begin
    WR_n <= 1;      // Disable writes
    Counter <= 0;
end
else begin
    WR_n <= 0;
    Counter <= Counter + 1;
end
end
endmodule

And this is how the report menu looks like:


texts:
As a result of calculations, I get a float (4 bytes and big endian) which I need to convert to hexadecimal to send it through the UART. How can this conversion be done? I have not found any examples that work for me. Thanks in advance.

EDIT: I have found this method from a library for arduino. Could you do something similar in C?

String Akeru::toHex(float f){
byte * b = (byte*) & f;

String bytes = "";
for (int i=0; i<4; i++)
{
    if (b[i] <= 0xF) // single char
    {
        bytes.concat("0"); // add a "0" to make sure every byte is read correctly
    }
    bytes.concat(String(b[i], 16));
}
return bytes;

}

EDIT_02: I have tried the code suggested by the first post response (by @jonk) and I do not get the expected result. For a float 63.72, the result should be '427ee148' and I get '0000e148 '. Could it be because the microcontroller is 16 bits?
This is the tested code:

#include <msp430g2553.h>
#include <stdio.h>

#define STRSIGFOXLENGHT 10

char strSigfox[STRSIGFOXLENGHT];
float f = 63.72;

void toHex( float fv, char * buf );

int main(void) {

    WDTCTL = WDTPW | WDTHOLD;   // Stop watchdog timer

    toHex(f,strSigfox);
    return 0;
}

void toHex( float fv, char * buf ) {
    sprintf( buf, "%08X", *(unsigned long *) &fv );
}

Thanks again.

EDIT_03: This is the code that works fine after the correction of Jonk:

#include <msp430g2553.h>
#include <stdio.h>

#define STRSIGFOXLENGHT 10

char strSigfox[STRSIGFOXLENGHT];
float f = 63.72f;

void toHex( float fv, char * buf );

int main(void) {

    WDTCTL = WDTPW | WDTHOLD;   // Stop watchdog timer

    toHex(f,strSigfox);
    return 0;
}

void toHex( float fv, char * buf ) {
    sprintf( buf, "%08lX", *(unsigned long *) &fv );
}

Thank you very much to all.


texts: How do I calculate the total wattage of a dc to dc circuit?

texts:
I am trying to figure out the total wattage of the below assumed dc to dc converter circuit block diagram.

Can I get it simply by just multiplying the total SUM of the system output voltages by total SUM of the system output Amps, like this:

(3.3 + 3.3 + 6 + 6 + 9) X (.5 + .5 + 2 + 2 + 2.5) =

(27.6V) X (7.5A) = 207W ???

Is that how we calculate it?


texts:
I'm trying to make simple lamp switching circuit to work, but it just doesn't want to work as intended - question is, why?

I'm using MOC3021 random phase optotriac with BT136/600E sensitive gate triac in such configuration:

simulate this circuit – Schematic created using CircuitLab

First thing - voltage V3 does nothing to this circuit - doesn't matter whether it's high nor low nor variable (zero-cross depending) - hot side never reatcs to it.

Second thing - depending on R3 (I've read somewhere that it's necessary if triac is sensitive) - if I plug this resistor, triac is always on, but if resistor isn't there - triac is always off. And it never reacts to optotriac U2.

Last thing - and very weird one - in configuration without R3 resistor, if I try to measure voltage on triac's gate, bulb sometimes flashes for half a second or so and the voltage drops from 230V to 30V and goes up again - same happens when I'm plugging/unplugging mains plug - looks like there's some connectivity problem, but there's none, checked it.

I haven't used a snubber for now, because lamp is resistive load so it shouldn't make any difference.. right?

And yes, I've checked the triac and optotriac, they seem to be good, even exchanged both with new ones - still the same.

What can be wrong with this circuit?

Regards


texts: P-N Diodes in series. Is my solution correct?

texts:
I have attempted to work out a solution on a short question relating to p-n diodes. Is my solution correct?

The question (from a past paper) :

From the question I understand that there are two parts:

Give the relationship between the reverse saturation currents of the two diodes.
Using the given values, determine the saturation current in diode D2

My attempt:

1.

Does this seem like an appropriately given relationship between the saturation currents? And is it correct?

2.

Im not sure if it's correct to equate the ideal diode equations this way, or if I have calculated VD1 correctly.
Any advice or help will be greatly appreciated, and if anyone has noticed something terribly wrong with my logic, please let me know.
Many thanks in advance.


texts:
Open Delta yields 57% of power instead of the 86% it would yield if no 30-degree angle gets in the way. Can that 30-degree angle be corrected with a capacitor and an inductor (it requires a cap in one phase and an inductor in the other phase)?? (it behaves like a power factor which is not caused by a load -- assume a resistive load).

This is a common question for those using power transmission systems.  The two part question is: 1. Why can't an open delta with deliver two-thirds of the power of a balanced delta, if the loads are the same on the two remaining windings?  and 2. Can this power be achieved by the addition of reactive components?


texts: What is the maximum output current of an OP27?

texts:
How much current can an OP27 supply (happily) ?

The closest thing I can find on the datasheet is the short-circuit current (~30mA).


texts: Joining nichrome wire within 1140 celsius kiln

texts:
I am trying to join 2.5mm diameter nichrome wire in my wife’s pottery kiln (1200 degrees celsius.)
I can’t find nichrome inline crimps, copper crimps won’t last. I am resorting to a steel bolt compression join as I think steel bolts(6mm or 1/4 inch) won’t melt.  I just need conductivity 240VAC, but am not sure if there is an alternative to replacing the whole element.
Maybe someone has tried this before. It doesn’t have to look pretty but must maintain electro/mechanical strength, it runs about 10 amps, but 1200 celsius


texts: Why is the modulating shape appear in both sides of the carrier signal in AM?

texts:
It's about Amplitude Modulation. Can anyone tell me why is this signal wave or modulating waveform shape appears in both sides of the carrier sine wave? Why not in one side only?

$$x_c(t) = A_c[1 + \mu x_m(t)]\cos(\omega_ct)$$

I copied this image from Wikipedia


texts: How to write a counter in verilog for debouncing an input?

texts:
I am trying to write a module counter to debounce a input coming from mechanical buttons. The module should be controlled by the 4x4 matrix button module when to start or stop debonce.

This is my counter module

module counter(input clk,input start, input[25:0] stateToGo ,output reg finished);
  reg [25:0]state = 0;
  reg [25:0]nextState = 0;
  //state register
  always@(posedge clk)begin
    state <= nextState;
  end
  //output CL
  always@(posedge clk)begin
    if (start == 1)begin
        if(state == stateToGo)
            finished = 1;
        else
            finished = 0;
    end
  end
  //next state CL
  always@(posedge clk)begin
    if(start == 1)begin
        if(state == stateToGo)
            nextState = 0;
        else
            nextState = state + 1;
    end
  end
endmodule

And this other is my keyboardScanner module, but when I connect them witha top module and try to press a button no input is taken from the keyboardScanner:

module keyboardScanner (input wait100,input wait20, input [3:0] col, output reg start,output reg [3:0] row, output reg [7:0] keyCode);
  reg [1:0]state=2'b00;
  reg [1:0]nextState=2'b01;

  //state register
  always@(posedge wait100) begin
    state <= nextState;
  end

  //output CL
  always@(posedge wait100) begin
    case (state)
    2'b00: row <= 4'b0001;
    2'b01: row <= 4'b0010;
    2'b10: row <= 4'b0100;
    2'b11: row <= 4'b1000;
    default: row <= 4'b0001;
    endcase
    if (col != 4'b0000)
        start = 1;
    if (col != 4'b0000 && wait20 == 1) begin
    keyCode <= {row[1],row[2],row[3],row[0], col[0],col[1],col[2],col[3]};
      start = 0;
    end
  end

  //next state CL
  always @(posedge wait100) begin
    if(wait20 == 0 && start == 1)begin
        case (state)
            2'b00: nextState <= 2'b01;
            2'b01: nextState <= 2'b10;
            2'b10: nextState <= 2'b11;
            2'b11: nextState <= 2'b00;
            default: nextState <= 2'b00;
        endcase
    end
  end

endmodule

Anything going wrong with my counter?
If I use CLK and no counter the inputs are taken pretty good from the keyboardScanner FSM

This is my top module with counter:

module comboModule(input clk, input  [3:0]col,output [3:0] row, output CA,CB,CC,CD,CE,CF,CG,AN0,AN1,AN2,AN3,output [7:0]kCode);
     wire finish20,finish100,starter;
     counter c20(clk,starter,26'b00000000011000011010100000, finish20);
     counter c100(clk,1 ,26'b00000001111010000100100000, finish100);
     keyboardScanner kScan(finish100,finish20,col,starter,row,kCode);
     SevenSegment SS(clk, kCode,CA,CB,CC,CD,CE,CF,CG,AN0,AN1,AN2,AN3);
endmodule


texts: What is the right way to understand the behaviour of shocking voltage?

texts:
I am just a starter and I am reading some beginner material about electricity.

I have some problem understanding this page which was about shock current path.

The writer explained why the bird is not shocked while the man got shocked:

  This might lend one to believe that its impossible to be shocked by
  electricity by only touching a single wire. Like the birds, if we're
  sure to touch only one wire at a time, we'll be safe, right?
  Unfortunately, this is not correct. Unlike birds, people are usually
  standing on the ground when they contact a "live" wire. Many times,
  one side of a power system will be intentionally connected to earth
  ground, and so the person touching a single wire is actually making
  contact between two points in the circuit (the wire and earth ground):

While I know that current flows from the negative end to the positive end, I had a concept ( which is probably wrong ) that after passing through the load, the energy would be consumed and therefore it is safe for anybody to tough the positive side of the wire.

On the other hand, the writer said the bird is not shocked because the bird didn't complete the circuit if the bird only put 1 foot on the wire. And even though if the bird put both legs on the wire, a circuit for the current was completed, the 2 legs were electrically common so there is no voltage across them. I think the man in the picture are in similar situation but he was shocked. How come? Does the present of the load make a difference? What if the load is removed, and the man grabs both the negative end and positive end of the powered wire?

EDIT

I read the chapter again. According to it:

  If connecting wire resistance is very little or none, we can regard
  the connected points in a circuit as being electrically common. That
  is, points 1 and 2 in the above circuits may be physically joined
  close together or far apart, and it doesn't matter for any voltage or
  resistance measurements relative to those points. The same goes for
  points 3 and 4. It is as if the ends of the resistor were attached
  directly across the terminals of the battery, so far as our Ohm's Law
  calculations and voltage measurements are concerned. This is useful to
  know, because it means you can re-draw a circuit diagram or re-wire a
  circuit, shortening or lengthening the wires as desired without
  appreciably impacting the circuit's function. All that matters is that
  the components attach to each other in the same sequence.

The whole theory of electrically common is based on the fact that the wire got very little or none Resistance so that it require almost no voltage to push the current from point 2 to point 1. However, if we consider the bird is on its 2 legs, it would form another path for the current and the resistance is somehow much larger than the wire. I think it is the Resistance of the bird itself matters. Am I right?


texts: Why is my radio circuit not functioning correctly?

texts:
Ive built this circuit and it hasnt functioned correctly it picks up a humming which im pretty sure it is my power supply

Can someone explain why this isnt operating as a radio? and maybe assist me with a functional radio circuit


texts: Detecting a short in an enclosed circuit with a PLC

texts:
I have an LED circuit that may or may not have a short. It looks somewhat like the image below. The short is labeled 500 ohm in the drawing. The short can actually be anywhere from < 1 ohm to millions of ohms. There can be anywhere from one set of three LED's to 30 - 40 sets of three LED's in parallel. Two sets of three LED's are shown in the image below.

I need to have front line employees test thousands of these for the short. I want to make a PLC that will do the following:

Provide power for the circuit
Detect if the wires from the PLC are not connected to the circuit
Check if the wire from the PLC are correctly connected to the circuit.
Tell the operator if there is a short, the tester is not connected or if the tester is connected and the part does not have a short.

I was originally and wrongfully thinking that I could have the PLC do a series of two alternating tests:

Test A. Power the circuit normally (positive to positive, negative to negative) and check voltages or amps being drawn.

Test B. Power the circuit reversed (positive to negative, negative to positive) and test for voltage.

I am now officially over my head. Does anybody have any suggestions of a test algorithm that will determine polarity of the circuit, if there is a short and if the wires are making connection?


texts: Can a majority of DC electronics run on high current (i.e. lamp, car) batteries directly?

texts:
I've seen some people run an inverter off a large set of batteries, to power mobile devices and whatnot or even game consoles. My thoughts are, if I can rig some lamp batteries together and use a portable tv I could power something such as an SNES (super nintendo/famicom).

The SNES would require 12V (suitable for some larger batteries, or some in series) and ~200mA possibly less when running. Would it be a good idea to plug a battery directly in to where the DC socket is, sans the regulation and all that? Does the adapter provide some sort of expected power or behavior different from a "pure" DC source?

Also a silly question, assuming I've a pile of 6V lamp batteries that could supply 100mA each - would I be able to place them in series+parallel to achieve 12V + higher maximum current draw for this purpose?


texts: Is LSM303dlhc INT1 active HI and DRDY active LO?

texts:
I just want to make sure I am approaching my LSM303DLHC design properly, and
that I'm correct in the active state of the two pins.

I setup the following registers as indicated:

CTRL_REG1_A:  77
CTRL_REG2_A:  00
CTRL_REG3_A:  10
CTRL_REG4_A:  88
CTRL_REG5_A:  00
CTRL_REG6_A:  00   (ooops - had forgot this one)

CRA_REG_M:    1C
CRB_REG_M:    80
MR_REG_M:     00
INT1_CFG_A:   00
INT2_CFG_A:   00
CLICK_CFG_A:  00

I then use the INT1 PIN as an accelerometer data ready flag, where it is active HI (1 = new data available).

I then read all 6 Acc data registers (OUT_X_L_A - OUT_Z_H_A, bytes B0 - B5) sequentially, and end up with values ...

   B1 B0    B3 B2    B5 B4
   XX X0    YY Y0    ZZ Z0

I use the DRDY PIN as a magnetometer data ready flag, where it is active LO (0 = new data available).

I then read all 6 Mag data registers (OUT_X_H_M - OUT_Y_L_M, bytes B0 - B5) sequentially, and end up with values ...

   B0 B1    B2 B3    B4 B5
   0X XX    0Z ZZ    0Y YY

Are the Z/Y registers for Mag data really oriented differently then the Acc data ?


texts: How Do These Kind of Power Switches/Systems Work?

texts: Just about all power switches in DIY electronic projects, such as Arduino, simply cut off the power source immediately when you turn it off. However, there are devices like 3D printers that when you push the power button to turn off, it does a few last tasks before the power actually cuts off. These tasks include running the motors to specific positions and writing a goodbye message on the display. How do these type of power down buttons/systems works? I don't know the exact name for these types of power buttons as well. If someone could explain what they are and how they work, that'd be greatly appreciated!


texts:
I was looking at the data sheet of a counter IC and the connection circuit diagram showed two connections: Vbb and Vtt

What do these mean? Is it related to the differential inputs the if supports?


texts: Some questions regarding a schmitt-trigger design

texts:
This question is about a circuit I want to use as a schmitt-trigger and is directly related to my previous question. I modified that and changed the output with suggestion of some users. Here is the circuit:

(please click to view the image in bigger size)

In brief, the goal of this circuit is to sharpen the incoming pulses which will have either 12V or 24V amplitude where Vcc will be same as the pulse amplitude.

But I still have five questions regarding this circuit and wanted to open as a new question not to bother and bombard the same users with several questions.

Here are my questions:

1-) I set the hysteresis around 1V. But to do that I modified R1. Do modifying R1 requires to modify R7 and R8 as well? In simulation I get the result I want but still I wonder if there must be a relation between R1 and R7 + R8.

2-) Is R2 necessary? What could be the reason for that?

3-) Why is C1 set to 1uF but not 100nF which is the typical value?

4-) ZD1 and ZD2 forms a surge protection. Is it better to let them stay there or move them right after C2, (between C2 and the inverting input)?

5-) In some examples I see speed up capacitors across R1 and R4. Do I need them in this case and what are they needed for?


texts: How to control the brightness of this 7 segment LED display?

texts:
This is how I tried to connect a BT-M512RD-DR1 LED panel, but it doesn't really work. This is the datasheet. Basically I have just used 2 wires of the 10 k\$\Omega\$ potentiometer. There is no change in brightness.

So again, the question is - what is the proper way to connect the brightness control pot to the LED display?


texts: Charging 2 Li-Ion Batteries via a single charger

texts:
I'm currently building a portable USB charger. It uses 2 Li-ion batteries in series connected to a USB port via a 5V regulated buck converter. While a single Li-ion battery would suffice for most applications, this USB charger needs to be able to output 1A at 5V; a single Li-ion battery of the type I have is only able to output 1A at 3-4V, or a max of 3-4W - therefore stepping up the voltage would reduce the maximum current output. The converter itself is not an issue other than requiring more than 5V to operate (hence wiring the batteries in series to produce an input voltage of 6-8V), since it has a maximum current output of 3A.

For the purposes of charging, I have a relatively cheap TP4056 charging micro-board specifically designed for charging 3.6V nominal batteries such as the ones I have. It's capable of CC-CV charging and automatic shutdown when current drops too low (indicating saturation). However, it's only designed for operating with one battery - as such, it can only detect whenever the battery it is connected to is full. Is there anything I could set up that would allow the charger to switch between batteries whenever one is full, and cease to charge either whenever both are full?

I imagine a relatively simple solution of a manual switch for operation after one battery is full might work, but this introduces micromanagement that I believe can be fairly easily avoided.


texts: why am i not getting square wave in vpulse pspice?What could have been the possible error?


texts: What is the failure mode of a solar panel?

texts:
I have understood that solar panels don't last forever. Warranties are typically a couple dozen years, and you can expect your panel to last for perhaps twice the warranty period.

But what does exactly happen when the panel is failing? Does it fail suddenly like computer hard disks, or does its output degrade like the capacity of batteries? What are the physical principles behind the failing solar panel? Is the failing in some way related to heat?

Do solar cells made by a reputable brand last longer than cheap Chinese cells?

Is it possible to make a solar panel that would last essentially forever given a high enough price is possible? Such a panel might prove useful if it turns out that the low interest rate environment will continue.

Of course, there are many types of solar cells, so the answer may be limited to the most common types, i.e. polycrystalline and monocrystalline silicon cells.


texts: One PSU powering one high power device & one low power device

texts: If one was to power a (potentially) multi-amp device and an arduino with an external LM7812 12v voltage regulator to a 19v laptop charger (in parallel), would the arduino be safe when the multi-amp device started pulling lots of current?


texts: Why we need the PCB Panelised for assembly?

texts:
I have a PCB finished in invidividual size for customer but they gave me comment that it can't be used by their assembly vendor and ask me make the new batch for them, When we make the board in 2 up only adding 2 rails with 5 mm per side and ask for the approval from customer ,they refused again and need the array in 4 up with routing and v-scoring , That will add the production cost much . Can somebody let me know why the assembly house need a extra up in one panel and prefer Routing than V-scoring ?

This is a square PCB with size of 100*120 mm ,when we make 2 up in the panel to get the size of 210*120 mm,then we can make the production panel size within 400*300 to get the best usage of the material.


texts: Does the voltage increase on 10Base2 and 10Base5 ethernet when the signal is reflected? Will this trigger the collision detection?

texts:
From what I understand, the collision detection will become true when the voltage on 10base2 or 10base5 coax is abnormal. Quote from Wikipedia:

  If termination is missing, or if there is a break in the cable, the AC signal on the bus is reflected, rather than dissipated when it reaches the end. This reflected signal is indistinguishable from a collision, and so no communication is possible.

So, when signal is reflected due to poor/no termination or there is break in the cable, it causes the voltage to increase along the 10Base2 and 10Base5 cables?


texts: How do I measure the duration of transient from a transient analysis graph?

texts:
I've assembled the following circuit:

And the following graph is the output: (Green: Voltage across C) (Red: Supply Voltage)

How do I measure the transient duration from the graph? Is it the same as the time period of oscillation?


texts: Will negative ESD strike pose any damages to I/O port connected to TVS?

texts: I understand that bidirectional TVS can withstand both positive and negative ESD strikes, with the positive ESD current is shunted to Ground through TVS whereas negative ESD current is shunted to I/O port. My question is will this have any impact on I/O port when negative ESD strikes as I know that I/O port will be in use and there is no way to let the negative ESD current shunt to it. Wish to seek for clarification on this. Thanks a lot for any replies.


texts: Pluggable terminal connector long term reliability

texts:
I'm investigating the issues related to long term reliability of pluggable terminals of "Phoenix" style. This terminals are available in a range of pitch and configurations (right angle, straight...). Look at the picture as example.

In my application I need to supply a control card with power in excess of 10A.
Currently the wire coming from the power supply is simply stripped and put into the terminal plug and then fastened with the terminal screw.
Is this method considered safe and reliable over many years of use?
The environment is clean and stable, no relevant vibrations.
Would it be better to pre-tin the stripped wire before screwing it into the terminal? Or should I use single wire terminals like the ones in the picture?
Or would it be better to use a pluggable connector which is itself crimpable?
I am aware that for reliability reasons, crimping should be preffered to soldering. Am I right?


texts:
I have made 2 H bridges following this schematic.
I have replaced
TIP107 with TIP147
TIP102 with TIP142
The Opto-couplers are P785.
I have not included the diodes as they are internal to the TIP.
I am trying to run two small toy car motor, max 2 Amp.
The power supply is 20V isolated, the plan is to PWM the ENA signal with an Arduino to adjust the Voltage to the motors.
Everything seems to work just fine on the bench.
However after a few minutes of running and stalling under load, the TIP seem to get quite hot and the motors stop responding in the direction the stall happened. The other side seems to be unaffected. When trying again after a few minutes, the affected side just gets hot, but no motion from the motor, while the unaffected side seems to work fine.
I have already replaced the TIPs a few times, a multimeter test shows some transistors don't turn off anymore, last time both PNP had continuity between collector and emitter with all power off.
I went over and over the control circuit, there seems to be no problem there.
Is there anything I might be getting wrong? I have to invert the PWM value in the code,
PWMValue= (255-PWMValue)
as the sides are actually active when ENA is low, so I am not sure if this is causing any problems, but as I said without load the motors run just fine.
Thanks in advance


texts: How are phase values able to capture motion from video?

texts:
I know that the phase spectrum contains most of the structural information about the image.
But I want to know more about importance of phase spectrum related to video signals.

I have read that temporal variations of phase values are able to capture most of the dynamical characteristics of the video sequence like global motion in the video.but i don't understand how it does?

please consider any real time example say video of rotating wheel or wave (or video of traffic on road.) if i compute its phase spectrum using Fourier Transform,the phase values captures motion of rotating wheel (or complex motion of moving car on road). but i don't understand how it does?By which property of Fourier transform could u explain it to me?

also is there any mathematical relation between motion and phase? please correct if i am getting wrong somewhere.


texts: 5V to 3.3V and 5V to 1.8 or 5V to 3.3V and 3.3V to 1.8V buck converters

texts:
I have a 5V power supply that is converted to 3.3V using a buck converter. Now I want a 1.8V supply. What is the industry standard way to feed a 1.8V buck converter? Do we feed it from the 5V supply or from the 3.3V supply?

From an efficiency point of view, I understand that the most efficient way may depend on the loads. Still, on buck converters, the efficiency gets worse, generally, as Vout is further away from Vin. But if I feed the 1.8V converter from the 3.3V one, I already have the power loss of the first one, albeit maybe getting a small boon from the increased current draw if I am on the side of the efficiency curve that favors an increase in current.

Nevertheless, what is generally done in this case? Two buck converters converting from the same supply, or one converting from the other?


texts: Eliminating oscillation in a feedback circuit

texts:
I have built a switch-mode power supply where the output voltage is controlled by a PWM signal from a microprocessor. The power supply is based on an XL4015. The feedback pin is normally fed by a passive resistor network that sets the output voltage- it's effectively a comparator relative to 1.25V. In this case the feedback pin is connected to the output of an op-amp which compares the output voltage with the filtered PWM voltage.

Vin is the PWM signal, Vout is the output voltage of the SMPSU and Vfb goes to the feedback pin on the XL4015. Unfortunately the circuit oscillates at about 10kHz, presumably because there is no gain-limiting feedback.

The red trace is the feedback signal, and the blue trace is the ripple on the SMPSU output voltage. The steps in the ripple are caused by the 40kHz operating frequency of the SMPSU.

Is there a simple change to this circuit that will make it more stable?


texts: Forming synchronous SR flip flop from asynchronous SR flip flop

texts:
Wikipedia gives following circuits of flip flops:

SR latch using NORs

SR latch using NANDs

Clocked SR latch using NORs:

Clocked SR latch using NANDs:

I understand how circuit 3 is obtained from circuit 1. It just involves ANDing clock input with inputs in circuit 1, especially it preserves the order of input. That is, note that in circuit 1, we have R input at top and S below it. Same is the case in circuit 3.

However in circuit 4, which seems to have obtained by NANDing clock input with inputs of circuit 2, the order of inputs seems to have reversed. In circuit 2, we have S' at top and R' below it, whereas in circuit 4, we have R at top and S below it. Should it be S at the top and R below it, in circuit 4?


texts: load sharing circuit power supply and battery with turn off mechanism

texts: I have my power supply VDD with 5 V. If my power supply is connected to the circuit, the MOSFET M1 should block my battery voltage. If the power supply is disconnected (VDD = 0), the transistor M1 should let my battery voltage pass. Additionally, I have build another transistor M2, I want to use to manually disconnect my battery if something unexpected happens. The circuit left of M2 is designed to turn off the transistor if the µC stops sending a pulse. The problem is, if I try to disconnect the battery with M2, when VDD is 5 V it doesn't work. I still have 3.7 V between M2 and M1 and don't understand why this does not work or if I am misinterpreting the results.


texts:
I recently received a run of 10 PCBs from a manufacturer in China, and am worried they have begun to cut corners and source counterfeit parts. Here is why:

I had them do full turnkey production (PCB Fab, component procurement, assembly). I've used them in the past and they've been pretty good, albeit with an occasional mistake.

I noticed on 4 / 10 boards, the circuit below not behaving as expected:

simulate this circuit – Schematic created using CircuitLab

On the faulty boards, whereas we expect the gate voltages of Q3 + Q5 to be either ~0 V (if NOR output = 1 (5V)) or ~12 V (if NOR output = 0 (GND)), the gate voltages were anywhere from 3-7 V...

Here is why I'm suspicious of the parts:

We've used this exact circuit in previous iterations of the PCB, with the same manufacturer, and haven't seen this issue. Only changes are minor difference in PCB layout.
After I hand-removed Q1 Q3 and Q5, and replaced them with parts I had from Digikey, the circuit functions as expected. I've done this on 3 boards, and all 3 went from non-working to working.

The relevant NPN + PMOS part numbers are given below, here are datasheet links:
DMP3010
MBT2222

Alternatively if something seems fundamentally wrong with the circuit, I'm all ears. But it is a pretty common, simple circuit, and as mentioned one I've used in previous iterations with no problem.


texts:
I am trying to build a circuit that turns on a speaker when headphones are unplugged (so it like how our phones detect when our headphones are connected).

To do this, I was thinking of simply using a headphone socket and male jack. This way, when the male jack is plugged, the circuit between the positive and negative terminals of the socket is open (as shown in the picture), and the speaker will not have any power. However, when the male jack is unplugged, the circuit is closed, and the speaker will turn on.

The problem with this design is that I would like to be able to easily pull the male jack out, at angles. However, the problem with only using a female headphone socket is that the headphones can't be pulled out at an angle, but rather can only be pulled out straight. To solve this problem, I was thinking of attaching a dongle (aka headphone extension wire) to the fixed socket, and then plugging the headphones into that dongle. Now, I can pull the male jack freely, at whatever angle (since the dongle is free to rotate).

Dongle/extension:

However, the problem with doing that is that now, the socket's circuit is permanently open since the dongle is always plugged in and won't be removed. Does anyone have any ideas on how I can overcome this problem? Any suggestions or solutions to what I am trying to do? Please let me know if I should explain more details. Thanks!


texts:
I was trying to solve the below question.
As per my understanding at t=0+ the difference voltage between (Vnoninvering -Vinverting)=-2.5v so output will change to -5. After then as Vin increases it will behave like normal noninverting amplifier with gain 2. The output will be distorted to give 5v.

Edit: The question is to draw output waveform Vo over time where time varies from time=0 to time= infinity.


texts:
I am working with Atmega16 mc and it works on 5V. Also my project consists of IR sensors, LCD and few diodes. All of those works on 5V.
I am wondering how can i power this board.
I read somewhere  i can use USB or "Wall Wart" 5V power supply. Which do you think is better?
And if that would even work? Also i know i need few capacitors 0.1uF there but not sure how many.

Yes, i am new to this field. It is my first project. I am working on smart parking, which means when IR detects car is parked, LED diode turns off and the display says how many parking spots are left.

There are 4 parking slots, but i am not sure yet how long wires would be. For now i am concentrated just on scheme and how to connect power supply with components. Do i need a voltage regulator for 5V supply? And do i need a bypass capasitors connected near?


texts: What does the output current rating from an H-Bridge's datasheet really mean?

texts:
I bought the H-Bridge VNH7070BAS from ST because it would drive up to 15A, but when I test it, it only reaches 6A and then it shuts down.

What does that value really mean?
How can I get the output current continuous value?


texts: Does lexical analysis map well onto FPGAs?

texts: From what I understand, a lexer that parses a language (e.g., C) is essentially a state machine that builds a list of tokens (essentially pointers) it finds in the source code. Has anyone ever considered whether or not this problem maps well to FPGA architectures?


texts: How to calculate Resonance Frequency of Audio Speaker?

texts:
Okay so I searched all over the Web for the resonance frequency of my car speaker so I can properly apply crossover filters, but didn't found any reference of the resonance frequency of this speaker model.

So how can I calculate it?

I have the following data:

Peak power: 150w
Rms power: 20w
Response Frequency: 90Hz-20kHz
Sensitivity: 91db/W/m
4 ohm

Thank you in advance!!


texts: Saturation Point of a magnet given some Parameters

texts: I know from my hard magnets (the remanent magnetization is very close to the saturated magnetization) the Coercivity \$h_c\$, the energy product \$B-H\$ and the remanent magnetization \$m_{rs}\$. Is it possible to estimate the value for the saturation field that I must apply?


texts: Who is responsible for panelizing solder paste layers?

texts:
When creating small PCBs, it is often convenient to panelize them for higher volume production.  In my package of gerber files, I include all the layers for one image, and then include a PDF detailing the dimensions of the panel.

This has worked great for ordering PCBs from multiple fabricators, but when we presented the PCBs and gerbers to the assembly house, we were asked to provide fully panelized paste layers so they can order the solder paste stencils.

I worked at an electronic assembly house for 8 years, and we always panelized the paste layer for the customer.  Is there an industry standard expectation for this?


texts: What is the component in the schematic below?

texts:
I have a problem with identifying components labeled by P1, P2 and so on.
The schematic is described as anticoincidence circuit in Polish (I think it's the closest translation), however searching online does not show results similar to the circuit below.


texts: I'm trying to find this contact for a 3d printer

texts:
So one of the contacts that detect the cartridge in my 3d printer broke. I'm trying to find a similar generic contact that I can solder on. It's for a discontinued CubePro so I doubt I'll find any original parts. Where would I find this type of PCB mounted contact? Mouser.com? I'm not sure what it is called either..
Thank You!


texts: Reading from SPI flash more than 35 bytes causes driver timeout and results to corrupt

texts:
I have connected SPI flash to my linux board (imx 233 based) running in it's SPI bus.
I have configured kernel, and SPI bus and flash chip to it.

The flash is currently on a breadboard. Before trying to work on linux, I tried separately and I'm able to read and write as I like with a FT2232H chip (FT2232 breakout board by dangerousprototypes.com).
However, linux-board, I had to add pull-up resistors (10k) in the data in and data out lines, the chip was not recognized correctly otherwise.

My actual problem is that now I'm trying to just read raw flash through mtd driver, and everything seems correct, if I read less than 35 bytes.
Immediately if I read more than 35 bytes (36 or more), the driver complains about DMA error:

[  521.700000] mxs-spi 80034000.ssp: DMA transfer timeout
[  521.700000] spi_master spi32766: failed to transfer one message from queue

Also when this happens, most of (if not all) the bytes will be incorrect..
Reading less than 35 bytes will return "immediately" (no timeout), and all bytes read will be correct.

My C code is straight from MTD read example:

int main(int argc, char * argv[])
{

    if (argc != 2)
    {
    printf("Need arguments how many chars to read\nExiting...\n");
    return 1;
    }

    int amount = atoi(argv[1]);
    printf("reading (%d) chars\n", amount);

    mtd_info_t mtd_info;
    int fd = open("/dev/mtd0", O_RDONLY);
    ioctl(fd, MEMGETINFO, &mtd_info);

    printf("MTD type: %u\n", mtd_info.type);
    printf("MTD total size : %u bytes\n", mtd_info.size);
    printf("MTD erase size : %u bytes\n", mtd_info.erasesize);

    /* read buffer */
    unsigned char buf[amount];

    read(fd, buf, sizeof(buf));

    int i = 0;

    for (i = 0; i < amount; i++)
    {
            printf("%i: %X\n",i,buf[i]);
    }
return 0;
}

The timeout happens "as expected" (10 seconds) in spi-mxs.c:

drivers/spi/spi-msx.c:
static int mxs_spi_txrx_dma(...):
....
ret = wait_for_completion_timeout(&spi->c, msecs_to_jiffies(SSP_TIMEOUT));

Any ideas what might be wrong ? I'm not that good with electronics, so please all suggestions are welcome.


texts:
I want to use a nand flash ic with part number of K9F1G08U0C and connect it to a stm32f429igt6 microcontroller.

Although I can read the ID of this nand successfully but the written data and read back, are not the same.- I just read 0x31 -

I can also see the control signals with my logic analyzer and they are all acting as the datasheet says.

here is my test codes:

{
    static NAND_AddressTypeDef WriteReadAddr;
    static NAND_IDTypeDef NAND_ID;
    static uint8_t TxBuffer [2048];
    static uint8_t RxBuffer [2048];

    HAL_NAND_Reset(&hnand1);
    HAL_Delay(100);

    /* Read the NAND memory ID */
    HAL_NAND_Read_ID(&hnand1, &NAND_ID);
    HAL_Delay(100);

    /* Fill the buffer to send */
    for (int i = 0; i < 2048; i++ )
    {
        RxBuffer[i] = 0;
    }

    /* Fill the buffer to send */
    for (int i = 0; i < 2048; i++ )
    {
        TxBuffer[i] = i;
    }

    /* NAND memory address to write to */
    WriteReadAddr.Plane = 0;
    WriteReadAddr.Block = 2;
    WriteReadAddr.Page = 0;

    /* Erase the NAND first Block */
    if( HAL_NAND_Erase_Block(&hnand1, &WriteReadAddr) != HAL_OK)
    {

        while(1);
    }
    HAL_Delay(100);

    /* Write data to FMC NAND memory */
    if(HAL_NAND_Write_Page(&hnand1, &WriteReadAddr, TxBuffer, 1) != HAL_OK)
    {
        while(1);
    }
    HAL_Delay(100);

    /* Read data from FMC NAND memory */
    if(HAL_NAND_Read_Page(&hnand1, &WriteReadAddr, RxBuffer, 1) != HAL_OK)
    {
        while(1);
    }

    /* check date */
    if(memcmp(TxBuffer,RxBuffer,sizeof(TxBuffer)) == 0 )
        printf("\r\n\r\n NandFlash Read Write Test OK\r\n");
    else
    {
        printf("\r\n\r\n NandFlash Read Write False\r\n");
        while(1);
    }

}

and as you can see I use the hal nand flash library.

Here is how I init fmc peripheral:

static void MX_FMC_Init(void)
    {
      FMC_NAND_PCC_TimingTypeDef ComSpaceTiming;
      FMC_NAND_PCC_TimingTypeDef AttSpaceTiming;

      /** Perform the NAND2 memory initialization sequence
      */
      hnand2.Instance = FMC_NAND_DEVICE;
      /* hnand2.Init */
      hnand2.Init.NandBank = FMC_NAND_BANK2;
      hnand2.Init.Waitfeature = FMC_NAND_PCC_WAIT_FEATURE_ENABLE;
      hnand2.Init.MemoryDataWidth = FMC_NAND_PCC_MEM_BUS_WIDTH_8;
      hnand2.Init.EccComputation = FMC_NAND_ECC_DISABLE;
      hnand2.Init.ECCPageSize = FMC_NAND_ECC_PAGE_SIZE_256BYTE;
      hnand2.Init.TCLRSetupTime = 8;
      hnand2.Init.TARSetupTime = 8;
      /* hnand2.Config */
      hnand2.Config.PageSize = 2048;
      hnand2.Config.SpareAreaSize = 64;
      hnand2.Config.BlockSize = 64;
      hnand2.Config.BlockNbr = 1024;
      hnand2.Config.PlaneNbr = 1;
      hnand2.Config.PlaneSize = 1024;
      hnand2.Config.ExtraCommandEnable = DISABLE;
      /* ComSpaceTiming */
      ComSpaceTiming.SetupTime = 0xF5;
      ComSpaceTiming.WaitSetupTime = 0xF3;
      ComSpaceTiming.HoldSetupTime = 0xF2;
      ComSpaceTiming.HiZSetupTime = 0xF5;
      /* AttSpaceTiming */
      AttSpaceTiming.SetupTime = 0xF5;
      AttSpaceTiming.WaitSetupTime = 0xF3;
      AttSpaceTiming.HoldSetupTime = 0xF2;
      AttSpaceTiming.HiZSetupTime = 0xF5;

      if (HAL_NAND_Init(&hnand2, &ComSpaceTiming, &AttSpaceTiming) != HAL_OK)
      {
        Error_Handler( );
      }

    }

And if you need furthur information you can download the whole project here:
https://www.dropbox.com/s/ro2nl2sssghympi/test_nand_flash.rar?dl=0


texts: What is the meaning of this datasheet diameter notation?

texts:
I am reading this datasheet and I want to drill the correct size hole into the board and I am confused what 5-ø1.2 means.

I can't understand what the 5 and - sign mean? Your help would be greatly appreciated.


texts:
Consider an overhead transmission line (not cable) and from whatever reason, one phase is out. Now, if secondary side of transformer at the beginning of transmission line is grounded star, there will be some not negligible voltage in the phase that is out (potential difference between line and ground). On the other hand, if secondary side of transformer is delta, voltage of phase that is out will be zero. Why is that happening?
Type of load doesn't matter, it is not affecting this results. These are voltmeters connected to ground


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I've been designing a test bench for RC propulsion systems and for that I thought it would be nice to be able to switch the power to the ESC on/off. For this I designed a simple circuit which I thought would do the trick. Vaa is used for both driving the gate and the ESC. However, as it turns out, the ESC GND is internally connected to the GND of its servo connection. First this means that the ESC never turns off. Second, this is quite dangerous when the MOSFET source isn't pulled to GND (open switch)! In that case if someone was to open throttle, the current would most likely kill the flight controller instantly. Another downside is that it is only possible to use/simulate a 3S or 4S battery pack (maybe 2s but not optimal) since Vgs of the MOSFET can't go above 20V (5s is 21V when fully loaded).

I think I've come up with a solution to both these problems by switching in the high side of the ESC and using an isolated DC/DC converter to drive the gate. The converter converts a 5V signal to a 12V signal which is high enough for the Rds(on) to be low enough to support a current draw up to 40 Amps with appropriate cooling (6 W/mK thermal pad and 2.7 K/W heatsink). However, I'm not sure this setup will work as I've never worked with such a converter before.

My question is basically if there is an obvious mistake I've made and what this mistake might be. Also if you have any tips as to how this circuit might be improved you are more than welcome to give them!

PS: This is my first ever post on this website. Feel free to comment on the contents of my question and how I might improve future questions!


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I have similar situation, described here: MeanWell 3-in-1 dimming
So, I need to control MeanWell power by PWM signal from Arduino. I tried to simulate scematics, given as answer in that topic, but it seems doesn't work (in simulator).
Schematics:

Results:

As author of that topic mentioned in one of comments, Vg is about -0.47V, which is not enough to close BSS126. One extreme change is to remove 750k resistor.
Schematics:

Results:

As you can see in this case Vg = -1.4V, which is still less, than required to close BSS126 comletely. I guess because of that maximum Vdim+ is not higher than 5.6V.
I'm quite bad at electronics and already spent a lot of time fighting with this schematics and trying to get 10V if there is no input signal for optocoupler. Can someone advise, what is wrong with this schematics and how to make it work? The goal is to have 0V when there is no input signal and 10V when input signal is 5V.
My MeanWell device is XLG-240-M-AB. When nothing is connected to DIM+ and DIM-, voltage is 14.4V. When I connect resistor 99.7 kOhm, voltage is 9.62V. Which means (if I'm not mistaken) that internal resistor inside MeanWell (please refer to schematics in topic, which I refered to previously) is about 50 kOhm


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I need a prototyping adapter for a ssop 24-pin package. Google turns up plenty of dip adapters for 5-7mm chips, but the chip I have is 3.9mm across the body and 6mm to the tips of the pins.

Anyone know of source of a suitable adapter?  Doesn't necessarily have to be a dip, just something solderable by humans.


texts: Calculating output impedance of Vbe multiplier

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I am trying to calculate the output impedance of the following Vbe multiplier,

simulate this circuit – Schematic created using CircuitLab

I have calculated the Vout = 4.2V and now I am trying to calculate the output impedance, so in order to do this I tried to do it by AC analysis. So got the below figure,

simulate this circuit

So now I am not sure how to process further, I know re//R1 and re = 1 / (40 * Ic) but after this how do I proceed further?


texts: RPi Pressure Sensor using Piezo Transducer

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I am trying to make a pressure sensor to use with my raspberry pi zero. I would like to avoid making another purchase, so while an ADC or FSR would be easier I would like to figure this method out.

Basically, I am trying to read a change in pressure using a piezo transducer on my raspberry pi. This is problematic because Pi is digital, and I cant measure voltage change accurately.

However, I found this method of measuring capacitance (using timer): this article

I was wondering if I would be able to use the piezo transducer as a capacitor whose capacitance is dependent on pressure change.

Here is a diagram of the ciruit I have in mind:

simulate this circuit – Schematic created using CircuitLab

Would this possibly work?


texts: No CS pin available on components (external ADCs) with SPI interface to choose one

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The usecase is the measurment of 2 bipolar voltagea of max -+10. I use Arduino UNO (Atmega328) and two ADC components  (AD7893ANZ-10), datasheet available on https://www.analog.com/media/en/technical-documentation/data-sheets/AD7893.pdf

To use the SPI interface there are no CS pin and no  MOSI pin on the slaves (ADC) (see datasheet page9). The alternative solution for CS pin is explained in data sheet as following: " To chip select the AD7893 in systems where more than one device is connected to the 68HC11's serial port, a port bit, configured as an output from one of the 68HC11's parallel ports, can be used to gate on or off the serial clock to the AD7893. A simple AND function on this port bit and the serial clock from the 68HC11 will provide this function. The port bit should be high to select the AD7893 and low when it is not selected. ";

I tried to figure out how to realize the AND function but its not even clear for me if this is related to HW or SW.

I will be thanksfull for every help


texts: Triac Switching circuit with Optocoupler

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I am trying to control home devices using a microcontroller and a TRIAC. For switching, I intend to use an optocoupler and triac-based circuit. The circuit is given below (also plenty are available on the internet, but all are the same).

The question I want to ask is how much power load I can connect to it's terminal because I need to connect a 230V-50A device at its output. So will this circuit, switch On/Off that device.


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I am re architecting something that works. (laser range finder). This is a cost down excercise.
In the existing system I have separate boards for laser driver and afe. Now I am combining those and the clock for laser driver and the output of the afe will be coming and going on the same fpc cable. We are measuring tiny signals therefore usually the whole afe is shielded including the cables in the existing design.

Now imagine a 20 lane 0.5mm pitch fpc cable where pin 1 is laser clock and pin 20 is afe output. Apart from putting them opposite sides of the cable what else I can do to avoid cross talk. I though about insertin gnd lanes in between but that is very much it.

What is the best practice in these cases?


texts: What is this connector? Round 8 pins, 5 notches on metal shell

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I'm looking at the output connector of a Lambda TCR600S1 power supply.  It looks like this:

This has 8 pins and a metal shell with 5 notches on the inside, and what looks like some locking pins on the outside.  It is supposed to be rated to high voltages (>600V).  What is it?

(Unfortunately I have no documentation for this power suppply.  I've used Lambda power supplies before, they usually come with screw terminals)


texts: Help understanding this LED lighting transistor circuit

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I simulated this circuit from a reference design but I'm not entirely sure how it's working or how you would go about designing such a thing. In simulation it looks like it's designed to hold the current through D1 constant at around 5mA despite having an input voltage range of up to 25V.

I see the gate voltage for M1 is held at about 1.6V, and the base voltage for the BJT rises as the input voltage rises.  So as the voltage rises the current through the BJT increases so it's acting like an adjustable impedance there I guess to hold the gate voltage constant.  Is that right?

Is this the kind of thing you just do in spice or is some kind of current mirror circuit that's well defined somewhere and I just don't recognize it?