texts: Calculating the voltage out of this particular cap coupled circuit

texts:
Before I get to my question, I'll just go over the input and output of the circuit from what I "know". The base of the BJT gets a 20 microsecond pulse that puts the bjt well into saturation and "VOUT" goes into a unity gain buffer to be measured somehow.

Questions: At steady state, both C1 and C2 should have 9V from plate to plate on each of them, correct? Then, while the base of the BJT gets a pulse and is in saturation with VCE(sat) = 0.5v,  the voltage on the opposite plate of C1 goes from 0 to -7.5? What does this cause to happen at C2 and how do I calculate the voltage drop across the resistor between them?

I hope that's enough information to give you an understanding of my lack of understanding. Thanks.

simulate this circuit – Schematic created using CircuitLab


texts: Help identifying component on cisco switch SGD110D-08

texts:
first of all thanks for taking time helping me with this issue.

TL;DR; Identify the blew up component on the picture and win!

I've by mistake done a very short but effective connection in reverse polarity to my cisco switch. Apparently only one component blew up and I pretend to replace it and see if I can save the switch as it is brand new.

During the "explosion"  of the component part of it's name got deleted but I'm pretty sure that someone with more experience (or maybe someone with the same switch and good will) can help me identify the component.

Here's the best picture I can take:
https://i.imgur.com/xsBTAjJ.jpg

Here's the whole PCB for some context:
https://i.imgur.com/CLVEgWY.jpg

The model is SG110D-08 it's a 8-port gigabit switch.

Thanks!

EDIT 1:

New photo cleaned up with some alcohol.

https://i.imgur.com/ozozCIf.jpg


texts: The reason for multimeters to have a high input impedance

texts:
My question applies not only to multimeters, but all devices which require a low or a high impedance at the input or output.
Based on my understanding, a device would require a high input impedance, so that the input signal does not get affected by it. In other words, if the circuit was like shown below, then at point A, the effective input signal would be like an output at the voltage divider, hence Rinput / (Rinput + R_source), but since R_input is large, this value will likely become close to unity.

simulate this circuit – Schematic created using CircuitLab
Am I correct in understanding this? Also, is it the same reason multimeters have a high impedance? I.e., so the measurement is not affected and is correct?


texts:
Is there a method for sequencing 4-bit binary numbers, where no 4 consecutive bits are repeated anywhere else in the stream?

For example;

Is there a method that would work for 5 and 6 bit numbers?

Thanks for all the great feedback. Here is some info on how the sequence is used:

Pictured below is the data placed on a wheel. As it spins, the bit stream is shifted into a software register from right to left. After 3 shifts, I have a valid number. After the 4th shift, I have the next number and because of its unique position in the sequence, I can associate it to a position on the wheel. Granted it’s not an absolute position system on power up, but after 4 shifts the position is found.

I’ve expanded this to six bits, but the process was manual. I’m looking for help to make scaling-up a bit easier.

Thanks.


texts: With a 555 + 4017, how do I light 7 LEDs, then 6, then 5... then 1 then 0?

texts:
I'm in the process of turning a Raspberry Pi project into a simpler circuit board powered with 555 and 4017 chips.

I want to be able to start by showing 7 LEDs, then go to 6 then to 5 and so on until all are dimmed.

I'll take a simple example with 3 LEDs:
LED 1 lights if the board is in state [0].
LED 2 lights if the board is in state [0 OR 1].
LED 3 lights if the board is in state [0, 1 or 2].
Nothing is connected to the board for state [3].
Thus in the board's state of 0, LEDs 1, 2 and 3 light.  In state 1, LEDs 2 and 3 light.  In state 2, only LED 3 lights.  In state 3, nothing lights.

I had tried using the step by step outputs of the 4017 chip and diodes to form an OR circuit, but I think I have all the LEDs in series (draining too much voltage) so the resultant brightness with more than a couple of LEDs is terrible.

Question 1: How can I have the LEDs counting down (AND with good voltage to the LEDs when they are lit), as above?

Question 2: The LEDs are just one half of the circuit board.  How can I make sure that once the 4017 chip enters its eighth state, the LEDs STAY off (until the circuit board's power is turned off and on again)?  The examples I'm finding on the web seem to circle continuously.  Thanks.


texts: Complimentary N - P mosfet circuit does not fully turn off

texts:
The following circuit does not operate as I hoped. There is between 1.5-1.6V on the output when the input is low. The circuit switches high correctly (Vout = 24V) and there doesn't appear to be any overcurrent as it does so.

simulate this circuit – Schematic created using CircuitLab

I have tried disconnecting the NPN driver circuit and directly connecting the gates to ground. This has negligible effect. This leads to me to believe the top N-Channel mosfet has been damaged, although I'd also expect the P-Channel to conduct and I would see a large current draw. This doesn't appear to be happening.

I cannot discount damage to the mosfets as these have come from a donor board.

If there anything glaringly obvious that I have missed please say so.

Thanks.


texts: Migrating uVision project within the same controller family

texts:
I've have a uVision project which is built on STM32F030C8 microcontroller. I'm using STM32F0xx standard peripheral library in my application. Now I need to migrate to a higher version of the controller, as my application demands more peripherals. So I now have hands on the STM32F071C8T6.

Now my question is: What changes do I need to make in my current uVision project files, so that the project can be safely migrated to support the STM32F071 uController?

Things done so far...

Updated the package installer for STM32F071C8T6 device.
Changed the device in "Options for Target" from STM32F030C8 to STM32F071C8T6.

What additional changes should I make?

The standard peripheral library will remain the same in my case right? ie STM32F0xx standard peripheral library.

Also, do I need to make changes in the startup files too?

Please tell me what files need to be changed, so that I can migrate my project logically without any conflicts.


texts: Mathematically derived waveform vs. captured waveform from an analog synthesizer

texts:
I was thinking about how the individual parameters on an analog synthesizer could be controlled digitally. What I mean is, instead of using mechanical potentiometers to adjust some quality of the waveform (for example, the frequency of an LFO), use digital potentiometers. This would allow numerical control of waveform synthesis, similar to how CNC machining produces metal parts.

If the analog output signal was then sampled, couldn't this data be analyzed in comparison to the virtual waveform used by the digital control process? And by this I mean one could see how close the analog signal comes to its intended waveform. There inevitably will be some deviation between the virtual and actual waveforms, in the same way that tolerances describe the deviation of machined parts from their intended dimensions.

Could the analysis then be used to subtract one waveform from the other (within some specified tolerance - if a measured value is close enough to the idealized value, that evaluates as being part of the signal), so that any remaining signal (that didn't cancel out during subtraction) would be the unavoidable noise produced by analog circuits?

If so, could this calculated noise floor then be applied to the original to reduce audio artifacts and so enhance the original analog signal? I assume this would be impossible to do in real time (due to propagation delays), but possible if done in post-production. The intent of which would be to blend the qualities of analog that continue to be in demand with the qualities of digital that make it so popular.

So to summarize, use digital technology to tightly control the operation of analog circuits in a musical synthesizer to produce an output signal that matches very precisely the digital waveform modeled from digital simulations, so that a process could be developed (similar to what's used in noise cancelling headphones) which would produce an enhanced (cleaned up) hybrid of analog and digital?

I'm sure that my electro-fantasy falls flat on its face somewhere, but I'm curious to know where, why, and how badly!

I used the synthesizer as an example, because I didn't know what the term for something was, or to describe something so I could demonstrate (and test) my comprehension. That's why the descriptions are rather long winded, but I really wanted to lay everything out to check accuracy.

The adding & subtracting of signals and the whole process is what I was ultimately interested in. And I'm happy I stumbled upon things I was interested in, but didn't know existed: the "distortion analyzer" and how the difference signal [is] (called the "residual").

I wasn't trying to be misleading with the question. It's just that I didn't know what I was describing was already a thing that existed. Sorry to have created a lot of responses on the subject of the double blind test, and how to go about developing the synthesizer I described. My main interest was about restoring or enhancing old recordings. I've always wondered about such a possibility and how much improvement could be made.

So I'm super happy to have gotten the answer that I accepted. Lucky is getting just what I was after without knowing what to ask for :+D


texts: Current increases when circuit resistance is increased while measuring black box device power consumption

texts:
The circuit is powered with 3V a battery and contains a black box device who's power consumption we're measuring with a shunt. The rated required voltage for the device is 3V. Whit a 1 Ohm shunt, the voltage drop on the shunt is 50mV meaning that the most of the voltage drop is caused by the black box device. Image name: Case 1.

However, the device power consumptions needs to be measured in an environment where we can't physically place the measuring equipment so we have to use long wires that add 10 Ohms of resistance in the circuit.  Image name: Case 2

simulate this circuit – Schematic created using CircuitLab

After the installation we were expecting to measure a decreased current and to probably conclude that doe to additional resistance this doesn't represent the power consumption of the device. However, we've experienced that the current in the circuit has increased almost twice. The only explanation for this is that the voltage drop has for somehow decreased.

Is it a reasonable assumption that the device has detected a voltage decrease on its ends and switched to a lesser resistance mode to be able to consume more power? The reasoning for this assumption is that given that the device is battery powered, it is prepared for a voltage drop and has a mechanism to cope with it.


texts: Cortex M7 goes to HardFault immediately after reset

texts:
I am using the ATSAME70Q21 processor with a Cortex-M7 CPU.

My development environment is Atmel Studio 7.  I am using the SAME70 XPlained demo board.

I am creating some code in assembly language.

As a test I setup a vector table at the start of flash (0x00400000) which contain the initial stack pointer value and the location of the Reset_Handler in the first 8 bytes.

When I hit reset on the debugger the Program counter gets set to 0x0040001C (which is correct).  The instruction at location 0x0040001C is 0xC046 which is a NOP.  The next several instructions in memory are NOPs also.

If I single step the debugger (execute the NOP) the program counter immediately jumps to the HardFault_Handler.

I don't see how executing a NOP can generate a HardFault.

What are likely reasons for a HardFault to occur immediately after reset.

I don't think its a hardware issue since I am using an off the shelf demo board and the problem doesn't occur if I use one of the example C projects in Atmel studio.


texts: I opened up a remote I had and saw there were two soft "objects" next to the display in it. What is it's name and function?


texts: STM32 ADC: Multiple channels with different sampling rates

texts:
I am trying to figure out how the STM32 multiple channels ADC conversion works (regular group). Lets say I want to convert on two channels, channel 1 and channel 2, on ADC1 and the sampling rates are 1 Hz and 10 Hz respectively (not actual numbers). I enable the setting to get an ADC EOC interrupt on each conversion (EOCS bit), which mean for each converted value the ISR is triggered and run.

I assume for the given sampling rates that the ISR will be triggered once every second for channel 1 and ten times every second for channel 2.

In the ISR, do I have to keep a track on which channel triggered the ISR or is there some register i can check that contains this information? How is this usually done?

If I were to use the DMA, how would the data be arranged? Would it be an array where every 11th value would be the channel 1 data and the rest channel 2 data?


texts: I just purchased a DC bench power supply from Ebay.  I have been trying to power up an op-amp circuit but with no luck.  I checked the voltage of each output terminal with reference to the ground(earth ground) on the power supply.  There is the correct positive potential but the negative terminal is showing no difference in potential as compared to ground.  I am correct in believing this should show the negative 15V I am looking for and not 0V correct?


texts: Confusion with braking-effect of a motor

texts:
To have overview I read the information at this link  where braking is explained.

Now I deal with a motor where it is recommended with a large uF capacitor under the regeneration section.

The linear motor model I deal with is 72V DC.

I have two questions:

For the linear motor to operate is this 72V DC converted to 3-phase AC?
I'm recommended to install a capacitor across 72 V DC of this motor. Does that mean I'm adding a DC link capacitor? And in the first tutorial link it doesn't tell any benefit of the capacitor. What does such a large capacitor do regarding braking effect? What is that used for?

To be updated...


texts: How to model devices external to FPGA in a testbench?

texts:
FPGA could connect to lot of devices like memory devices (SRAM, SDRAM, DDR RAMs), data converters and various other complex ICs. Is it a normal practice to model them in a testbench to make verification "complete"? I assume that doing so will atleast require a cycle accurate behavioural model.

Lets take example of SRAM or SDRAM, is it normal practice to use some sort of cycle accurate model of these memory devices in a testbench?


texts: Scrolling wheel encoder with button push button action into wheel axis

texts:
I am looking for a wheel that you can push into as a button as well as scroll indefinitely in either direction.

Here's the exact part I am talking about. I'm not sure exactly what it is called.

The ultimate goal is to be able to tell a direction of the scroll and how fast the scroll is in order to cycle through options and to be able to press into the wheel to confirm a selection.

I've found so far something called a "Rotary B Click" which indefinitely scrolls in either direction and has a button but the button action is in the wrong direction (towards the board instead of towards the wheel axis). It also seems that it is a rather large component, I am looking for something smaller.

I also found this component(potentiometer) which only rotates once and doesn't click but visually looks close to the component I'm looking for.


texts:
How can I create a digital counter that counts from 000 to 111 and automatically starts reverse counting from 111 to 000. I have tried with simulation it works fine, but with actual ICs I am not getting a proper output.

The following is the hand-made version of the circuit diagram that I simulated on cedar:

original fuzzy image

The top ones are 7 D flip-flops and the bottom ones are three JK flip-flops implementing the up-down counter.


texts:
I have 2 blower motors. I know where they came from and what the models are but I cannot find any real info on them, and I don't know motors enough to know what I have or how to use them. I dabble in electronics a little but I am limited in certain aspects, stepper motors for example.

They are 2 blow motors from working REMStar Plus CPAP machines. I nabbed them in hopes I could use the blowers. I checked the voltage with my meter (in auto mode) coming off the green/black/white cable and all the pins fluctuated between 4.7-4.9 VAC no matter which pin combination I tested. I did not check the other smaller cable. The green/black/white cable appears to be the power, the other I think is for sensor data or something, it will run without the smaller harness plugged in. It looks like the motor comes off some NDS8858H chips, via google they appear to be mosfet half bridges?

What kind of motors are these (AC, DC, PWM, stepper etc)? How can I use them (what is required to talk to them, straight power or PWM etc)? I want to use them with an arduino or raspberry pi if possible. Thanks!

Here are some pictures.

This is the back of the board the motor connects to, the harness traces out (visually) to these chips.

The motor

The side of the motor


texts: Movement of Electricity in a Simple Circuit: A Few Simple Questions and a Diagram

texts:
The diagram above is of two batteries a light bulb and some cables. A book that I am reading shows that electricity would not flow through the blue cable, it would flow through the red cable. This left me with the following questions:

Is this even true? why wouldn't some of the electrons from the battery on the right still try to flow to the battery on the left? (this kind of relates to question 3).
Also suppose that the cable extending from the negative terminal (the anode) of the battery on the left was many times longer than the length of the cable extending from anode of the battery on the right, in such a case would electricity be transferred from the anode of the battery on the right to the positive terminal (cathode) of the battery on the left? In other words do the electrons take the path of least resistance?
Pardon the analogy that follows; would a sort of traffic jam be created where the blue and the red cable connect? I mean once the electron from one battery started flowing to the cathode, would they impede other electrons from joining the flow?


texts:
I have a electronic device that says it should be powered at 10 - 24 V 300mA max

I have a power plug witch outputs 12 V 1.1 A

Can I connect the plug to the device ?

Somebody told me I can if is true :  Why is that ?


texts:
I have this in an exercise and it asks me to find the frequency of the CPU. I know how to calculate it for smaller drawings, but how many times does every I-Mem, Add, MUX, ALU, Regs, D-Mem and Control run?

*I Calculated at about 740MHz but the solution is 783, so this is why i'm asking you.

I-Mem = 412ps
Add  =  120ps
MUX  =  21ps
ALU  =  120ps
Regs =  197ps
D-Mem = 351ps
Control=115ps


texts: Reading a potentiometer with an unknown voltage

texts:
I have a potentiometer that ranges from 0-400kΩ.  One pole is connected to a supply of unknown voltage (but it's in the neighborhood of 12-14V: it's a vehicle power supply).  The other pole is connected to my circuit.  I would like a circuit whose voltage varies from 0 to 3.3V based only on the value of the potentiometer, for feeding into a microcontroller.  That is, varying the supply voltage should not affect the output voltage.

Of course, this would be trivial if the supply voltage were fixed:  just use a voltage divider!  The untrustworthy supply (which I can't rewire) makes it much more challenging, however.  I suspect that this simply cannot be done with simple resistors.

How should the "black box" in the schematic below be wired?

simulate this circuit – Schematic created using CircuitLab


texts: coils/Inductors in series for power transfer

texts:
I have an air core inductor that I want to use for resonant coupling purposes. This inductor has an inductance value of 500nH. Is it ok to connect another inductor with a value of 100uH in series with the first one, to increase the value of inductance, but to only use first air core inductor for resonant coupling?

In short, I want low inductance value antenna in distance from the circuit and second higher value inductor in series with the antenna.


texts:
I am currently working on a project to make my own coilgun. But a bit unsure of the driver circuit. Typically, a driver circuit will look something like this: Flyback diode and a mosfet being the primary components.

For and infinite coil the  magnetic field can be calculated by the equation B=μ0nI. So I can increase the magnetic field by either increasing the number of turns or increasing the current. Currently I have a power supply capable of 30v, 5A (starts as a constant voltage source, but if the current limit is reached it will act as a constant current source, up until the voltage limit is hit). I would also like to experiment with different current levels (ie 1A, 3A, etc).
How are the coils usually current limited? Thinking about it, if I look at a motor and its driver circuit (H bridge), it seems to me that the coil is allowed to draw as much current as it wants, which depends on ohms law, Voltage/Resistance of coil. Then the user controls the voltage instead. Am I correct in this assumption? Are there any other things I need to keep in mind when designing this driver?
ie: if I want the coil to run at 1A, and say it has 5hm resistance, I will need to supply it with 5V.


texts:
i want to use a lithium-ion battery as backup for my circuit in vehicle.
i scare about explosion and safety . i decided to use TP4056 ic but many batteries has not temperature pin .

-
can i use temperature sensor ?
what is your suggest for extreme safety especially in car ?


texts: Multiple SDRAM modules vs single IC / Latency relevance

texts:
I'm designing a board with a ARM Cortex processor (TI Sitara). It needs an external RAM module, and I have never really worked with embedded SDRAM modules in circuit design. Looking at the schematic of the evaluation board for the chosen processor, it can be seen that the eval. board uses 4 smaller RAM modules instead of a single 2GB RAM module.

Are there any advantages of doing that? Also, the "cheaper" RAM modules all seem to have higher CL Latencies (CL-11 @ 800MHz). The board will do real time audio processing, do you think that latency is important in this case?


texts: Why signal deteriorate in half-duplex UART communication in long wire (6 meter)?

texts: I am doing project on half-duplex UART communication between two AVR microcontrollers. I am using n-mosfet based push pull circuit in both transmitter and receiver side. 3.3 V signals transmission is okay for the short distance but for longer distance (6 meter), signals deteriorate (shape of pulse becomes pointed and voltage drops) and signal is not anymore valid on receiver side. I need to setup the communication at least 10 meter. Circuit I am implementing is given below. It needs to be low power.


texts: When is it better to have a high voltage and when is it better to have a high current?

texts: What are the advantages of each? What situation would I want higher amperage than voltage, and vice versa?


texts: How do 3-phase dual voltage motor windings work?

texts: Many 3-phase motors allow for two possible line voltages, for example 230/460.   I am trying to understand how the different wiring is changing the way the windings get current.  I would guess that wiring for high voltage the motor would use all the windings and when wiring for low voltage it would only utilize half the windings. But, wouldn't that would give the motor different performance and draw ratings depending on how it is wired?  Can someone explain how the current is traveling in both the high and low voltage wiring scenarios?  Where are the poles?  Thank you!


texts: How do you program the SMD ATMega328 IC in an inexpensive way?I know you can get a factory to program the chips but is there a way to program them with Arduino without one of those expensive sockets.


texts:
I had a device come with no USB cable.

Since it used a proprietary USB connector on the device side, I decided to solder a male USB A cable directly on the motherboard pins.

The USB device is correctly detected, and shows up in the device list, both with dmesg and lsusb. The device name, identifiers, etc. are correct, but the daemon that is supposed to communicate with it over hidraw (I think) fails to do so.

So, in short, my problem is the following:

USB device correctly detected (correct vendor and product ID, matching product string)
USB communication not possible.

The cable or connection is likely the culprit, I didn't double-check my wiring because of a lack of time avalable with the device. I wasn't able to find good documentation on hardware USB troubleshooting online, but I seem to recall that inverting D+ and D- could cause such issues (detection, but no communication).
Even if that ends up being the issue, are there resources for troubleshooting that kind of problem? What are the possible causes for this failure mode, and how should I go about debugging it?

The USB cable is quite short, but of quite poor quality (I had no regrets sacrificing it).


texts: How to wire up single phase induction motor?

texts: I bought a single phase induction motor with two capacitors, but I do not know how to read the wiring diagram on this motor.


texts: Solar Panel & Temperature coefficient of Voc Seems Exceedingly Low

texts:
I am reading over a solar panel data sheet and I'm having issue converting the Temperature coefficient of Voc as written because it seems exceedingly low to me. I fully understand the panel datasheet might be misleading as well but wanted to ensure my understand of the data provided was correct.
As I understand it most panels should have a temperature coefficient of VOC (open-circuit voltage) of -0.2 to -0.5 closer to absolute 0 being better.
The panel I am reading up on lists the temperature coefficient of VOC as -(80±10)mV/°C  which if I am not mistaken means -0.09/°C to -0.07V/°C. Am I reading the data correctly?
The following is the specifications of the panel incase I am missing some aspect. Thank you for your time.
Maximum power (Pmax) 100W
Voltage at Pmax (Vmp) 19.00V
Current at Pmax (Imp) 5.27A
Open-circuit voltage (Voc) 23.50V
Short-circuit current (Isc) 5.67A
Temperature coefficient of Voc -(80±10)mV/°C
Temperature coefficient of Isc (0.065±0.015)%/ °C
Temperature coefficient of power -(0.5±0.05)%/ °C
NOCT (Air 20°C; Sun 0.8kW/m² wind 1m/s) 47±2°C
Operating temperature -40°C to 85°C
Maximum system voltage 1000V DC
Power tolerance ± 3%


texts: I am disassembling a drone for a project. I found this silver boxy component on a side circuit board that connects to the main circuit board on one side, and to the camera of the drone on the other side. It has a small black thing sticking out of it, so I don't know exactly what it is. Could anyone identify it?


texts: How do I calculate the voltage across a capacitor when the source is a square wave?

texts: I have a series RC circuit with R= 2.2K Ohm and C=100 nF, and the voltage supply is a 2.5V peak square wave. And I'm not sure how to calculate the voltage across the capacitor.


texts: DHT11 Humidity/Temperature Sensor Interface with PIC18F4620

texts:
I'm trying to interface a PIC with the DHT11 sensor and it's not working. I feel I have tried everything. Below is a stripped down version of my code which should at least make the sensor send a response message.

Basically a LED should turn on as soon as I get a HIGH value from the sensor. But I'm not getting anything..

If someone could help to solve this it would be really great. I'm also attaching a picture of my set-up.

Thanks a lot!

#include <stdio.h>
#include <stdlib.h>
#include <delays.h>

// PIC18F4620 Configuration Bit Settings

#include <p18F4620.h>

#pragma config OSC = HSPLL      // Oscillator Selection bits (HS oscillator, PLL enabled (Clock Frequency = 4 x FOSC1))
#pragma config WDT = OFF
#pragma config PWRT = OFF       // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = OFF      // Brown-out Reset Enable bits (Brown-out Reset disabled in #pragma config WDT = OFF        // Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit))

#define DHT11_TRIS  TRISDbits.RD1
#define DHT11_IO    PORTDbits.RD1  //READ USING THIS

#define LED0_TRIS   TRISDbits.RD0
#define LED0_IO     PORTDbits.RD0

int my_flag = 0,bit_counter=39,t1=0,t2=0;

int response[]={0,0,0,0,0,0,0,0,0,0,
                0,0,0,0,0,0,0,0,0,0,
                0,0,0,0,0,0,0,0,0,0,
                0,0,0,0,0,0,0,0,0,0};

void high_isr(void);
void low_isr(void);

#pragma code InterruptVectorHigh = 0x08
void interrupt_at_high_vector(void)
{
_asm GOTO high_isr _endasm
}

#pragma code low_vector=0x18
void interrupt_at_low_vector(void)
{
_asm GOTO low_isr _endasm
}
#pragma code /* return to the default code section */
#pragma interrupt high_isr
void high_isr(void)
{
// return from high priority interrupt

}

#pragma interruptlow low_isr
void low_isr (void)
{
// return from low priority interrupt
}

#define GetSystemClock()    (32000000ul)
#define GetInstructionClock()   (GetSystemClock()/4)

void Delay10us(int us)  {
    Delay10TCYx(((GetInstructionClock()/1000000)*(us)));
}

void DelayMs(int ms){

    unsigned int _iTemp = (ms);
    while(_iTemp--)
    Delay1KTCYx((GetInstructionClock()+999999)/1000000);

}

void main(void){
    int c=0;
    CMCON = 7;

    DHT11_TRIS = 0; //Set DATA OUTPUT
    DHT11_IO = 0;

    LED0_TRIS = 0; //Set LED as OUTPUT
    LED0_IO=0;

    DHT11_IO = 1;

    DelayMs(1000);
    DHT11_IO = 0; //Pull Low
    DelayMs(20);  //For 20ms
    DHT11_IO = 1; //Set HIGH
    Delay10us(3);// For 30us
    DHT11_IO = 0;

    DHT11_TRIS = 1; //Set as input

    while (DHT11_IO !=1){}
    LED0_IO = 1;
    DelayMs(5000);
}

Edit: I would post my set-up but I'm not allowed due to rep points!


texts: Difference is Bluetooth Smart and Bluetooth audio

texts:
My name is Raveen Baloo. I have been doing a lot of research on the types of Bluetooth module. For my project, i do need a bluetooth which will be able to have simple communication with a mobile app, sending over sensor data and do simple command. The bluetooth chip should also be able to send continues data (playing music). Now, while doing my research, i found that bluetooth smart will be able to send data periodically and audio bluetooth sends continues data with DPS.

So will a Bluetooth Smart or smart ready be able to send continues data (streaming music) and will it be as good as the Bluetooth audio module which has DPS and aptx.?

Thanking in advance for you help guys.
Feel free to ask me if you dont understand my question. I'll try my level best to explain it again. Thanks again


texts: How to determine if conventional electronics circuit is a better choice over a MCU?

texts:
I am a software engineer and have limited experience with conventional circuitry. Recently, I have built a prototype device that uses an Arduino Uno, a Bluetooth module, an array of temperature/humidity sensors, and an OLED readout display, which currently relies on I2C. The function of my device is to simply wait to receive a BT signal, which wakes it from low power, then enables data acquisition by the temp. sensors for a fixed length of time while averaging at each read interval, and then displaying the averaged temp. & humid values on the OLED.
Ultimately, I am trying to determine if can move away from the ATmega328p chip and design a MCU-less circuit with conventional electronics for a production model. My project objectives motivating this idea are: achieving lower material and labor costs and eliminating the dependence on software and firmware. Both are equally important to me. However, I do not know if I am creating other substantial obstacles for myself in doing so. How can I determine 1) if what I’m asking is even possible to do given the functional requirements of my device and 2) if it’s the right choice going the MCU-less approach based off my project objectives?


texts: PCB coating for a high temperature environment

texts: What PCB coating is good for a high temperature environment (my environment is about 30-70 C), and is available in a spray can or so that is easy to implement without need of a device/machine?


texts:
I want to make a simple charger for my 2S1P battery. I found a lot of circuits using LDO regulators to get the typical CC/CV curve for Li-ion batteries like this:

but I wonder if it is possible to copy the 2N2222 circuit and use it in an adjustable SMPS regulator like LM2575-S for better efficiency. My idea is to use one of this BMS (between the charger and battery) to balance and protect the batteries. Is that possible? Thanks!


texts: How dangerous is soldering lithium ion phone battery, and how easy is messing up

texts:
I plan on leading a workshop on how to create led devices(shoes, clothing, etc), and mostly plan on teaching how to do it with old electronics, like phone batteries. The point is trying to do it as cheap as possible, so getting something like a spot welder is out of the question.

I plan on attaching something like the picture below to the phone battery, and it looks like the only cheap way to do that is by soldering it.

Questions

From what I've looked up it looks like the battery can explode

is this explosion big enough to actually hurt someone?
How easy is it for the battery to explode for someone with not a whole lot of experience?
If getting seriously hurt probably won't happen, is ruining the battery a serious concern?
Is there a better option to connect the battery to a power source?


texts: How do I determine the resultant permittivity of two different dielectric materials in a cylinder capacitor?

texts:
I am trying to calculate the density charge of the inner cylinder in the above picture.
If there was only one dielectric I would use the following equation:
$$
\frac{q_{enc}^f}{L} = \frac{2\pi \varepsilon_0 \varepsilon_r V (r_a)}{\ln (\frac{r_b}{r_a})}
$$
But how do I calculate with \$\varepsilon_{r_{1}}\$ and \$\varepsilon_{r_{2}}\$?
Material with \$\varepsilon_{r_{1}}\$ permittivity is in the area where \$r_1 < r < r_2\$ and \$\varepsilon_{r_{2}}\$ is where \$r_2 < r < r_3\$.


texts: stm32f103c8t6 : Problem in PWM generation on timer output channel

texts:
My Objective is to Generate PWM with duty cycle = 50 % , Frequency = 50 Hz using
 General Purpose Timer 2 in output channel 2 which is at PA1 or pin number 11 My Target System is STM32 BluePill development board

Target Controller is STM32F103C8T6 MEDIUM DENSITY DEVICE
Target    board crystal is   8 MHz
I use Keil Micro vision 4 evaluation version IDE for programming and debugging
Debugger : ST-LINK V2

I configured the GPIOA in Alternate function output Push Pull mode with maximum frequency not exceeding 50 MHz,  I connected an LED bulb to the GPIOA pin 1, but the LED went on glowing without reduction in the brightness level.
The LED was still glowing even after i performed a test with duty cycle set to 0. On the debugger window I could see exactly all the parameters I configured and the Count register was getting incremented. I cannot find information regarding selection of alternate functions for a GPIO Port.

my code:

/**************************** Header file *******************************/
#include<stm32f10x.h>

/*************************** user defined function **********************/

/************************************************************************
Name        : PWM_Init()
Description : Initializes PWM hardware and associated GPIO ports
              Enables clocks for peripherals and configure modes
Parameters  : None
Return_val  : None
************************************************************************/
void PWM_Init()
{

/****configure clocks for PORTA & TIMER2********/

  RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;           // enable port a clock
  RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;           // enable clock for timer 2

/*****  configure GPIOA mode *******************/

   /* Porta Pin 1 &2 as alternate function output Push pull 50 MHz */
    GPIOA->CRL = 0x000000bb;

/*******Set timer 2 Period for PWM**************
  Timer Clock                   = 72MHz = 72000000 Hz
  Time Period Required          = (1/50Hz) = 0.02 Seconds
  Let ARR value be 65535 then,
  Prescalar + 1                 = 72000000/((ARR+1)*50Hz)
  Prescalar                     = 21 (approx)
***********************************************/

    TIM2->ARR = 65535;                      // Set Auto reload value
    TIM2->PSC = 21;                         // Set Prescalar value

    /* Output Compare Mode, ENABLE Preload,PWM  mode:2*/
    TIM2->CCMR1  = 0x00007800;

    TIM2->EGR |= TIM_EGR_UG;       // ENABLE update generation

    /*CC2E : channel 2 enabled; polarity : active high*/

    TIM2->CCER = 0x00000010;

    TIM2->CR1 |= TIM_CR1_ARPE;      // Auto preload ENABLE
    TIM2->CR1 |= TIM_CR1_CEN;       // ENABLE Timer counter

}
/**************Main Function**********************************/
int main()
 {
    PWM_Init();                                  // initialize PWM

        while(1)
        {
            TIM2->CCR2  = 32768;                 // SET duty cycle to 50%
        }
  }

Kindly have a view of my source code and please notify me the corrections that need to be done. The target specifications are mentioned in the source code.

Thank you


texts: FOC electrical angle offset calculation with absolute encoder

texts:
I'm currently developing a motor controller with FOC (Field Oriented Control) and I have some trouble with the offset calibration of a motor.

What I actually do to calculate the offset:
I inject a voltage directly in the d-axis, such that the motor alignes. The offset is then chosen as this position. When I then calculate the electrical angle, I add PI/2, such that I get an alignement with the q-axis.

What I expect:
When the offset is chosen the right way with the method above, the motor produces the maximum amount of torque/ampere for the motor and it should run the same in both directions.

What I get:
The motor produces the maximum amount of torque, but the motor turns way better in one direction than the other. I see also high id spikes when this happens as shown below. When I manually adjust offset a little, then it turns the same in both directions and the spikes depicted below are gone, but it has no more the maximum torque.

What I further see is, that when I exchange the Phase U and W, it works better in the other direction, so the motor should not be the problem here. Has anyone an idea, what could cause this problems?


texts: I have basic knowledge about AVR microcontrollers and AVR programming.In this days i am trying to design bldc motor driver.I want to use atmega2560 for controller of this driver.For this purpose i need 6 PWM output in 20kHz.I have found i can change the prescalers , top values and modes of timers then i can get 20kHz signal.But i have doubt aboout can i use 6 PWM output at the same time for commutation (mosfet drivers) ? Can i accomplish it with software ? What is your suggestions about that ? And as you know atmega2560 has 6 timers : 2x8 bit and 4x16 bit.Which pwm pins are  more suitable for me according to your experience ? I will appreciate for your help.Regards ; (I know there is a lot of AVR documentation and app notes about BLDC. I have researched and read a lot of them in a week but i couldn’t find my answer.I am very confused)


texts: How do I take the larger of two analog signals?

texts: I have two feedback signals. I want to create a circuit that outputs the larger of the two. I know I could do this with diodes, but I'm unwilling to accept the diode drops. I suspect some op amp circuit would do the job, but I'm not sure how. What should this circuit look like?


texts: Industry standard ways of connecting boards / modules?

texts:
There are literally thousands of different types of connectors when I'm searching on a distributor such as element14, and I'm not sure what are the "standard" ways of connecting boards together.

Currently, when I need to connect two different boards together, I will use a 2.54mm spaced pin header, and some ribbon jumper wires. While this is fine for prototyping, I want a more standard solution to connecting modules together (such as USB, D-Sub, HDMI connectors, etc).

Digital Communications

The protocols I normally use a I2C and SPI, so Vcc, GND, and the bus wires (SDA, SCL, MOSI, etc). For these protocols, are there any standard physical connectors which I should use when I want to connect boards together? e.g. RJ45 or something? I've always associated RJ45 with telephone comms, so not sure if there are more appropriate standard connectors.

Analaogue Communications

For example, if I want to drive a motor or fan, what type of socket should I use on my board? On computer fans, hard drivers, toys, etc. I have seen them use Molex or some tiny white connector. Is this a standard way of connecting analogue input/outputs? AFAIK Molex is a brand of connectors, but nowadays is it just a name for the type/shape of connector?

Protocol-less digital communications

For example, push button switches, and LED lights, etc. How should I connect these between boards?

Finally, in my latest project I need to connect my around 20 different connections (these include both vcc/gnd lines, analogue inputs, switch inputs, as well as an I2C line, and some multiplexer line select lines,) between two boards. Should I have different connectors for each of these, or is there one standard connector I can use for all the pins?

The distance of communication I'm talking about is 1 - 2 meters at most, however any information regarding longer range communication is also appreciated.


texts: Which String methods got changed with Arduino 1.0?

texts:
It seems that several of the String methods (so far I'm sure it applies to trim() and the to upper/lower functions) in the Arduino library have been modified to alter the String rather than return a new one. Is there a complete list of which methods have been modified? The release notes have the following unhelpful statement:

  The String class has been reimplemented as well, by Paul Stoffregen. This   new version is more memory-efficient and robust. Some functions
  which   previously returned new string instances (e.g. trim() and
  toUpperCase())   have been changed to instead modify strings in place.

Thanks!


texts: limit LED current only with transistor and base resistor

texts:
I'm bit exciting about my new plan here, my goal is to make a small and simple 5W LED driver with Arduino. I know about current limiting resistor in series with led or in emitter pin of transistor, but just curious, can i driving LED with only transistor and base resistor to limit current going from collector to emitter?

simulate this circuit – Schematic created using CircuitLab

thanks


texts:
I am trying to identify this 5 pin SOT-23 regulator. It's labeled S80D (Maybe S8OD, the letter O not number 0). But a search for that top code does not come up with anything specific to it.

I do not recognize the logo used. It looks like a comma, or a lopsided rainbow. I have searched for the manufacturer logo on a few sites but nothing matches. Since it's not even an initial or recognizable shape, I can't even narrow it down.

No, it's not broken.


texts: How can I tap into and measure this rf frequency?

texts:
I'm new to rf design, although I'm learning rapidly.  I've designed a PCB which uses an ultra-wideband (UWB) transceiver.  The center frequency is selectable between 3.6GHz and 6.5GHz, with 500MHz bandwidth. I'm using a surface mount UWB chip antenna.

The application requires fairly precise frequency regulation.  The transceiver has a crystal trimming capability of +/-20ppm, in 32 steps.  The transceiver manufacturer recommends I assess the output center frequency while changing the trim values, and choose the value that gets me closest.

I have a frequency counter to measure the output frequency.  If I connect the PCB to the frequency counter with coax cable, I see the signal and can do the tuning.  Here are the specifications for the TF960 frequency counter.

Here's my difficulty:

I've connected an antenna to the frequency counter, but it won't pick up the signal over the air.  It is a fairly low-power signal; close to -39dBm/MHz.

In the rf path of the PCB, I left pads to create a pi filter for later tuning. The two locations to ground are unpopulated, and the series location has a zero-ohm "resistor".  All three are 0402.  When I attached my coax-to-SMA pigtail, I removed the series shunt to isolate the circuit from the chip antenna.  Then I scraped away some of the soldermask over a ground fill, and soldered the coax shield there.  We obviously can't do this to calibrate production PCBs.

(sorry for the photo color)

In the future, I'll choose higher-tolerance loading capacitors for the oscillator (they are now 5%), but I still hope to be able to do a non-destructive calibration.

My questions:

Should I be able to read the signal over the air?  It would make the rest of this easy. I'm currently using this chip antenna, both on my PCB and also plugged into the frequency counter. (I have a dev board from the antenna manufacturer to use with the counter).
Would a signal analyzer be more appropriate for this task than a frequency counter?  Are they more sensitive?  Budget is tight, hence the inexpensive frequency counter.
If I could find an rf probe (coax probe?) to land on the 0402 placements, can I use it with the chip antenna still in place?  I'm considering something like this one, although I'd have to find one for higher frequencies.
Is there a better way to do this?  I feel that I may be looking down the rabbit hole...

Thank you.


texts: What's the correct way to solder wires on that (LiPo) battery's terminals?

texts:
I need to solder a wire on each of the terminals on the battery shown below. They are approx. 15mm large.

Should I solder the wires, of use some sort of clamp? It looks like the terminals are made of aluminum, so soldering would not hold well.


texts: How do transistors and MOSFETs generate pulsating signals?

texts:
I see many circuits in which transistors or MOSFETs are used as "automatic" on and off switching devices. Can somebody explain how a MOSFET manages to pulse its gate within a circuit up to many hertz without outside interference?

An example would be the circuit of a joule thief. How is it possible that you use a couple of resistors and MOSFETs and make a pulsating signal?

I want to add a circuit as an example so somebody could maybe explain how the MOSFETs in this inverter cycle work and how they manage to turn on and off. It transforms 12 V DC into alternating current.

simulate this circuit – Schematic created using CircuitLab


texts:
I was handed the following circuit in order to determine what it does and what is its operating conditions. The circuit was reverse engineered from an old equipment.

I have simulated with NI Multisim v.11 and the oscilloscope shows only a constant voltage of 2.7[V], this are measured at \$C_3\$.

I need help to analyze this circuit in order to determine what it does, what is its output waveform and its operating conditions.

The op amp stage seems to me like a comparator/oscillator, it is  comparing \$V_0\$ which varies over time because of the capacitors against the 2.5[V] that is a square wave generator with 5V amplitud. So is this an square wave oscillator or what? What is its output?


texts:
I need to design a totem bole bjt based gate driver for Mosfet IRF640, which is going to be used in a Buck converter.

I know the peak gate charging current= 1A.

I've already selected my complementary Bjt pairs (2N2222A,2N2907A) so it can give a max current = 0.6A.

The mosfet has a minimum \$V_{gsth}\$ = 2V and max of 4V. Now how do I select Rg? Rg = [Vgg - V(gs,Io)]/ig.

From the equation:

1.On no load, I get Rg = [15-4]/0.6 = 18.33 ohms

On full load (Id=10A), V(gs,Io)=5.5V from datasheet, so Rg =[15-5.5]/0.6 = 15.84 ohms.
Considering -Vgg = -5V, I get Rg = [15-2-(-5)]/0.6 = 30 ohms.

Where should I use the peak gate charging current value of 1A?

Thanks in advance.


texts: Why is there no attenuation in the magnetic field at the boundary of the near field?

texts:
I have used the Wikipedia FSPL formula for the farfield, and the one kindly provided by @mnsp for the near field:

http://grouper.ieee.org/groups/802/15/pub/04/15-04-0417-02-004a-near-field-channel-model.pdf

To model the attenuation of the magnetic field across the spectrum. Low frequency magnets have a very quick attenuation by distance. For example a bar magnet easily loses it's influence after 3-4 cm. However as you increase the frequency, the attenuation is lowered, and it possibly reaches 0 right at the boundary of the near field.

In my thought experiment I have used a distance of 5 m to model this for a theoretical isotropic transmitter. The general formula is λ/(2*π) for the boundary.

So in our case we have pretty much close to 0 attenuation at 8.4 MHz, and it starts to go back up from there. Looks like this:

Here is the python3 code to remove any uncertainty how my calculations were done

import math

π  = math.pi    #pi
c0 = 299792458  #lightspeed
r = 5           #distance

#---------------------------CALCULATION---------------------------------------------------------

def FSPL(f):
 λ = (c0/f)
 k = (2 * π ) / λ

 PLANEWAVE= 20*math.log(f,10) + 20*math.log(r,10) + 20*math.log(4*π/c0,10)
 MAGNETIC  =abs(10*math.log(1/4  *  (  1/  (k*r)**2 + 1/  (k*r)**4     ) ,10))
 ELECTRIC  =abs(10*math.log(1/4  *  (  1/  (k*r)**2 - 1/  (k*r)**4 + 1/  (k*r)**6     ) ,10))

 if(r<(1/k)): #Fraunhofer Boundary
  return f,MAGNETIC,ELECTRIC  # Near Field
 else:
  return f,PLANEWAVE # Far Field

#------------------------------ITERATION--------------------------------------------------------

CYCLES=34
STEP=1
for i in range(0,CYCLES):
 print (FSPL(STEP))
 STEP=STEP*2

#------------------------------END--------------------------------------------------------------

Which begs the following questions:

What is exactly happening between the nearfield and farfield boundary?
Is the model theoretically accurate?


texts: How to calculate the current through load resistance in the given diagram?

texts:
I am here with yet another problem, where I have to find load current, ripple voltage, approx turns ratio? Also, any idea about how can we reduce ripple voltage further?

Attempt:
This is a step-down transformer and a half-wave rectifier circuit with a capacitor to reduce the ripple voltage at the output.
If the diode is Silicon, I assumed that the voltage drop across it is 0.7V.
Voltage at the junction of diode and capacitor is given 12.5V so 12.5+0.7= 13.2V is what we will receive as output of stepdown transformer.
To calculate approx turns ratio:
Vp/Vs=Np/Ns
so, 240/13.2=18.1818 is the approx turns ratio.
Current through load:
I=V/R
I=12.5/50 = 0.25A

Need guidance in order to figure out ripple voltage and how can we reduce it further?


texts:
I have a small buck dc-dc voltage converter that has two aluminium body capacitors mounted on the pcb surface. The top reads something like this:
220
HFP
1J9

Here's a photo of it...

I want to know what is the max voltage for this capacitor. I see similar circuit boards that have 35v or 50v capacitors (mostly 35v) but how do I know the voltage rating of this capacitor.

I understand the meaning of 220 that is 220uf but what does HFP and 1J9 means?

Thanks in advance.


texts: Is it efficient to run a linear regulator in dropout mode?

texts: In a battery powered application, it might be tempting to run a LDO in dropout mode as a LiPo battery falls from 4.2V to below 3.3V. Is this a normal thing to do, and would most regulators perform efficiently in dropout mode, or do you just have to select carefully for this quality based on the datasheet?


texts: Should all the GND pins of the JTAG be connected to GND?

texts:
I am using a TMS570 MCU with this debugger which has the 20-pin cTI JTAG pinout exposed in this page.
Should all the GND terminals be connected to the board's ground or it is sufficient just one?


texts: electronic component (perhaps an op amp) identification

texts:
I was looking through some components I got in a kit a few years ago, and I found what I think is an op-amp. Unfortunately, any documentation for the kit is long gone. (Although I don't think it was particularly useful to begin with) I would like to identify the component, but I can't seem to find any documentation online from the numbers on the chip. The logo loos like a "yw" but I can't find that anywhere either.
I got this part from a "Minitronics Survival Guts with 60+ components" package that was in a "Make: Raspberry Pi Starter Kit" from radioshack.
The text on the chip, as far as I can make out, reads:
UTC358D
(The Logo) P3M6DC
on the bottom of the chip, there is the code "J20" centered in a small circle.
Any Help is appreciated!
Thank You!


texts:
So, I want to make a High-Frequency Ferrite transformer that can convert my 150-volt peak Square wave into 100000 Volt Peak.
I am using UUR6440 Ferrite Core. Material is CF139
https://www.cosmoferrites.com/Downloads/Alnh/CF139.pdf.

Below is the chart of the material.

My power supply setup is Half-Bridge topology for now. In the final design, I will use the H bridge.
I have used 2* G4PC50UD Igbt to generate the Square wave.

For my design, I have used Bmax as 35mT, or 3500 gausses. I have calculated primary using this formula.(0.5 * Vin * 10^8)/ 4 * F * Bmax * Cross-section-Area). I have added 0.5 cause my design is Half Bridge. My switching Frequency is 50Khz. And my cross-section area is 2.9cm^2. So the result is 3.69 turn, so have used 4 turns in primary using 6mm square Wire. I need not more than 28mA in Secondary, so I have used 37AWG wire. And the secondary turn I have calculated using *(Vs/Vp)Np= 2666 Turns in secondary. But I have used 3000 turns in secondary.
Now the problem I am facing is while my secondary is at 0/NO loads,my Primary current is drawing 15-ampere peak at 40 volts RMS. When I am trying to give more voltage in the primary, the primary is drawing more current proportional to the primary voltage. Even when I am trying to generate an ARC in secondary the primary peak current is the remain the same. At 40 volt RMS my secondary should generate 4*666.66 = 26640 Volt. But the arc is only 1cm Long. My power is supply can provide up to 3KW.

So can I generate 100000 Volt at 28 milliamps using my current setup?

Why my ferrite transformer drawing 15amp peak at 40-volt RMS  at NO loads ?, I mean when the secondary is not generating any ARC or the secondary wires are not even close? I have measured the secondary wire resistance. The resistance is 535 ohms.

If my calculation is all wrong what you suggest I should be doing to generate 100000 Volts at 28 milliamps?

simulate this circuit – Schematic created using CircuitLab


texts:
I have recently purchased an 8-bit gaming console out of nostalgia, of course the light-gun that came with it did not work on modern LCD screens. Now I know that when you squeeze the trigger of the light gun this sends a signal to the console to draw an entirely black screen with just the position of the duck replaced by a white rectangle. Then if the gun is pointing at the duck/rectangle light will hit the photodiode in the gun's barrel and it will register an electrical signal and a subsequent "hit".

I know this does not work with modern TV's because of screen update lag. However I tried shining a flashlight into the gun's barrel and it did not register a hit, either. Then I tried checking if the diode worked, at all, so I used a multimeter to measure the voltage when it was being shined with a flashlight and when not. However, what I got was that the voltage only changed the first second or so when light hits the diode and after that the voltage came down to its usual level, even though the diode was still being shined on.

So far I don't know what I am doing wrong.

EDIT: i appreciate the answers, but it seems my question is unclear:
tl;dr - i know how LCD and CRT works, what i want to know is why the diode does not work when shined constantly with a flashlight


texts: How does this constant current sink actually work?

texts:
I have implemented a constant current source and it works wonderfully, but I was just hoping to try and understand it a little bit more! Here is the circuit in question:

I have tried doing some searching on the web and have found it quite difficult to find any theoretical things on this circuit that explain what is actually going on with everything. I did find out that the current through the transistor can be found simply by using $$I_{E}=\frac{V_{\text{set}}}{R_{\text{set}}}$$ which was a lot more than I knew before I started looking. But now I want to know what is actually going on and how it remains a constant current output even with a varying load/voltage at the load.

If anyone would be able to shed some light onto this, I would be highly appreciative.


texts:
In a previous question where a SMPS based on an LM5118 was presented, some aspects of the layout were pointed out as being problematic. I've taken another look at the layout of that section of the board and in light of the advice given, the IC datasheet and reference design, I've made some modifications to the layout with the aim of resolving any layout issues.

Here's the top side:

Bottom side (as viewed from top):

Schematic page 1:

Schematic page 2:

Things I've tried to keep in mind:

I've tried to keep the bottom layer continuous underneath the high current loops so that the return currents can travel along the bottom layer, directly beneath the top layer, thus minimising the loop area.
Separate ground area for the analogue section of the SMPS, connecting directly to the AGND pin.
Solid ground plane between PGND pins, input and output caps.
Gate signal for Q2 rerouted to move it away from the inductor and to try and improve its loop area.

I appreciate that other parts of the circuit (not shown) can have an effect on the layout as well, but if the SMPS section is considered separately, I was wondering what feedback people can give regarding the layout, and if there are any issues or improvements that could be made.


texts:
I have a STM32L MCU connected to M24LR64E, an I2C EEPROM. Previously i had this setup working but then i changed some things (layout, firmware) and somehow i screwed the I2C and it is not working now.

I'm using it with the I2C_DutyCycle_2 mode at 100khz, 4.7k pull-up on both SDA and SCL lines. Everything on the board is working at 3.3v. Below is a shot of both SCL/SDA lines on my scope, sadly i don't have a logic analizer to play with.

Most of the I2C shots that i've found on Google seems very 'nice' with square-like rise/fall signals, and mine looks very different.

Any suggestions? Does the attached image looks good for a I2C bus?

Thanks, a lot.


texts:
I am in the process of designing an SDR and have completed a block diagram of its architecture. Before proceeding with more thorough component identification, I was hoping to receive confirmation that the architecture is "sound." Epic success? Epic fail? Is there anything else that you would add/remove? etc.

Notice that I have at least identified the LT5516 and LTC5599. My plans are also to include a power detector for forward and reverse power detection. Dashed lines represent digital information, most likely via SPI. SPDT RF switches will be controlled via the DSP depending on whether the SDR is receiving or transmitting.

Any thoughts would be greatly appreciated!


texts: Q: Unexpected behavior from digital Rheostat

texts:
I have no idea whats warranting this behavior from the MCP4162 device

Starting from 500mV(pp) - 2.8V(pp) a weird "wave" like distortion happens in between the two voltages. (Towards the negative cycle).

This only happens at low frequencies such as 20Hz and lower, however at higher frequencies this no longer occurs even with the voltage range described above.

Input 1 = Input (Yellow)

Input 2 = Output (Green)

The behavior:

Diagram

simulate this circuit – Schematic created using CircuitLab


texts: Using two switches to each send current in opposite directions

texts: I have two momentary switches, one to activate a solenoid and one to reset it. It is only possible to press zero or one of the two switches at the same time. Using a single battery, how can I wire the circuit so one switch triggers the solenoid (sending current one way) and the other resets it (sending current the other direction)?


texts: Can I use a current control buck converter to charge a battery?

texts:
As shown below, could I use a microcontroller to charge the Li-ion battery? I'm unsure if I'll run into issues with the voltages on the ADC. I've done this exact setup before with a generic load, I'm unfamiliar with batteries though.

simulate this circuit – Schematic created using CircuitLab


texts: What's the difference between delayed branch and branch prediction?

texts: I'm studying how delayed branch works and I'm trying to distinguish delayed branch from branch prediction. What is the difference? Is delayed branch a means to facilitate a control hazard?


texts: Why is 1699 displayed when cheap multimeter is loading?

texts:
I'm talking about like this:

Why do we see 1699 the first second after we turn it to measure 750V~?

Is there some electrical logic behind this number, is this related to the chip used in the multimeter or is this the maximum number that can be displayed?


texts: What's the best way to store and categorise resistors/capacitors/ICs/etc?

texts:
I did a big cleanup of my collection of parts today and I now have a big pile of parts on my desk (the majority of which is resistors). My previous method of finding the resistor value I wanted was to look through my little box and read the colour codes. Unfortunately I now have a  lot of resistors, making an individual search almost impossible. Instead of reinventing the wheel, I put it to you my fellow chiphackers: do you know of any efficient (as in fast recall) ways to store and categorise components ?

I understand you can get lots of small drawers but it seems like such a waste of space to put only a single resistor of an unusual value in its own drawer.


texts: Small signal analysis of diode connected Field effect transistor

texts: How would I carry out small signal analysis of the above circuit to find  output resistance? Do I just set Vgs equal to Vds ?


texts: CAN Physical Layer With Different Characteristic Impedance

texts:
The company I have been working for, which is designing a new control system for forestry equipment, has encountered a number of problems with regards to the CAN bus it is using for communication. I work remotely doing design, and as such much of my information is second-hand.

I have been informed that when using a common cable type used in the industry and a data rate of 250kbps, the CAN bus often encounters errors which are frequent enough to stop communication on the bus. The cable used is approximately 15m in length, with 4 conductors for power and ground, and a pair of conductors for data that are not twisted or nor shielded.

Upon my recommendation, the company has now ordered a new cable with a shielded twisted-pair, but I was not involved with the specification of conductor sizes and insulation.

It is my hope that using this new cable will solve problems with regards to the lack of twisted-pairing, however, my concern is that the characteristic impedance of the new cable will not be near 120\$\Omega\$ , as specified for the high-speed CAN physical layer in ISO 11898-2.

When I calculated the characteristic impedance of the new cable using $$Z_o = \frac{276}{\sqrt{\epsilon_r}}*log(\frac{d}{r})$$
where \$\epsilon_r\$ is the insulation relative permittivity, \$d\$ is the distance between conductors, and \$r\$ is the conductor radius

I get a characteristic impedance of 187\$\Omega\$. This is obviously outside the recommendations of the CAN physical layer.

My question remains, to match the characteristic impedance of the transmission line, is it advisable to use a resistor value larger than 120\$\Omega\$? If not, would the difference be negligible enough that 120\$\Omega\$ would work fine or should I be advising them to look at a properly specified cable? I have never come across anything other than 120\$\Omega\$ for CAN, and would prefer that the transmission lines have the required characteristic impedance, but I'm trying to suggest a solution with the current hardware.

Thanks for any suggestions you may have.


texts:
What is the constitutive relashionship between current and voltage of a varistor in LTSpice? For example, if I set the control voltage V=1V and Rclamp=2, what is the formula to evaluate the resistance of varistor? I tried to do this simulation (I used a 10V voltage source in serie with R1=1 and a varistor), but the result it's strange for me. The current on R1 is 3A, \$V(R1)=R1\cdot I(R1)=1\cdot3=3V\$, but the resistance of varistor is not Rclamp=2 (is 7/3=2.3).
Thank you very much.


texts:
Photolithography would be new in our instituion and i could not ask any experts there about it, thats why i turned here.

I have created a photomask using an electrolithograpy proccess and am now stuck on how to QUANTITATIVELY evaluate the physical quality of the mask. I have googled that i can check the size consistency of the paterns (digital size to printed size on mask), thats it all i know, what else should i check for? Any help would be appeciated.

Edit

We will be using the mask in contack uv photolithography to create stuctures in silicon substrate within the micrometer range. By far, google have shown results on evaluating masks based on how good is it for producing stuctures. but few result show how to evaluate a photomask before creating the structures.


texts:
I need help on my design which includes a wind turbine, charge controller, battery and load.

The question is, what will happen to the load if the wind turbine is charging the battery and while it is not charging the battery? My load is a Raspberry Pi 3. What I mean is, when the battery is full, I know the charger controller will do its thing which cuts off current to the battery. Will the Raspberry Pi turn off? I need it to always run.

Also, if it does not turn off, wouldn't the Raspberry Pi discharge the battery while it is being charged by the turbine? Would I need a current greater than the load?


texts: Could impedance mismatch explain my distorted signal?

texts:
I have a custom PCB which scales and offsets an analogue signal, using an instrumentation op-amp (INA114). When I use a scope to look at the output, it looks distorted (see images below). When I use a T-junction at the input to look at both the input and output signals on the scope, the output is no longer distorted. What is the cause of this distortion?
Here is a diagram of the configuration:

The DAC spec says that its "load impedance" is \$50\Omega\$. The scope, I assume, has an impedance of \$1\text{M}\Omega\$. The custom PCB connects directly to the op-amp, which has an input impedance of \$1\text{M}\Omega\$. Schematic can be seen at https://imgur.com/jodTvBy.png.
And here are the good (both input and output connected to scope) and bad (only output connected to scope) waveforms:


texts: Why are EEPROM sizes measured in "k" or kbit and not kbyte or byte?

texts:
I keep seeing EEPROM datasheets using terms such as 4k, 16k, etc. and they're referring to 4 kilobit and 16 kilobit, bits, megabits, and kilobits are often used. Very seldom do they use byte prefixes. Some will also clarify with 512 * 8 bits, or 2048 * 8 bits.

Why isn't using bytes (or kilo-/mega-) preferred, as there's always 8-bits in a byte, and I've never heard of EEPROM that can't be divided into bytes.

I realize that kbit/Mbit is used in data communication, but I don't understand the relation because EEPROM is technically storage, not bandwidth. This applies to EEPROM, but also other similar types of memory like Flash or SRAM, etc.


texts: BA3121: Ground loop supression is great however very thin audio quality

texts:
Recently I bought a couple of BA3121s to fight the annoying ground loop problems when using several/separated modules (MCUs, BlueTooth, USB etc) in class-d amplifier audio projects and all the modules share the same power source.

For every solution provided, I made a test board (made it for isolation transformers, isolated DC/DC converters) but there always seem some downside to using it (see also footnote below). Not a fan of breadboards, like solid connections and mostly solder a demo board to try a new component.

Like this one, followed the application example mentioned in the datasheet and works pretty well however very thin sound. With thin sound I mean there is no bass. It sounds clear, stereo and noise free however no bass. It sound like a high pass filter. Checked the connections (ok), soldering, and wiring several times and is exactly the same like the example.

I don't think my result is the intention of the example, so what could be wrong? First thought is the small output decoupling capacitors (4.7uf) in the example which is pretty low and by using a bigger cap in serie (for example 100uf), on the output terminals there is more bass. However, by doing this, I change the characteristics of the circuit.

Question:

My question is, why do the manufacturer provide an example that produce low quality sound or do I miss something inhere? Or is there an error in the schematic? Can I replace the output caps and/or input caps with a larger capacity caps without changing the ground loop characteristics? What minimal value should be used?

Datasheet:

When you want to take a look at the datasheet, you can find it here and here.

footnote (not a part of the question):

Downsides found by using several different/other ground loop solutions:

Isolation transformers on the output (input amplifier) is cheap and easy however can be big and bulky, reduces output capacity (volume), can reduce bandwidth especially lower frequencies;
Isolated DC/DC converters, expensive and limited, can still introduce some whine, USB doesn't function when there is no common ground connection

UPDATE 08 may 2018

I'm very confused, the datasheet explain to increase the caps values on the Vm pins however when I do this, nothing happens, same harsh rich treble sound. They talk about CMMR and doesn't effect the sound quality but the noise suppression.

However when I change the output caps, tried 10uf, 22uf, 47uf, 100uf and 220uf. When using 100uf and 220uf there is no difference in sound quality and provides rich bass, so I think 100uf could be right. However there the harsh treble still exists, it is not the same as the original source, the treble is amplified.

There is even more confusion when I found the "evaluation board manual", it is practacly the same as the example in the datasheet however there are some resistors in serie on the input path with jumper pads to be able to bypass the resistor. Especially the 50k(!) resistor, which is enabled by default, really don't understand why you want to do this because it kills the signal completly (or am I wrong?).

Because it is practacily the same as the datasheet example, why I get thin sound using the example? I don't get it. Why do I need to change the output caps and why is the sound quality not the same?

You can find the "evaluation board manual" here


texts: Basic Robotics Help. Variable motor speed control by ultrasonic sensor input on arduino

texts:
First, thank you for taking the time to read my post.

I am attempting to use an ultrasonic sensor to control a DC motor using the PWM output of an arduino. Fairly simple, I know, but I'm just a beginner. :)

Here's my code, with an explanation of my theory and my error afterwards.

#define trigPin 7
#define echoPin 2
#define motorPin 9

void setup(){
 Serial.begin(9600);
 pinMode(trigPin, OUTPUT);
 pinMode(echoPin, INPUT);
 pinMode(motorPin, OUTPUT);
}

void loop(){
  int duration, distance;
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(1000);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2) /29.1;
  if (distance <5)
  {
    analogWrite(motorPin, 0);
  }
  else if(5 <= distance <15)
  {
    analogWrite(motorPin, 50);
  }
  else if(15 <= distance <25)
  {
    analogWrite(motorPin, 100);
  }
  else if(25 <= distance < 35)
  {
    analogWrite(motorPin, 150);
  }
  else if(35 <= distance < 45)
  {
    analogWrite(motorPin, 200);
  }
  else if(45 <= distance)
  {
    analogWrite(motorPin, 255);
  }
  else;
  {
    analogWrite(motorPin, 0);
  }
  Serial.print (distance);
  Serial.println (" cm");
  delay(500);
}

So, this is incredibly simple. I haven't yet begun differential drive nor braking, and soon I want to learn to change out the ultrasonic sensor programming with the NewPing library for more sensors and less delay.

Right now, I am hoping to have the arduino interpret the ultrasonic ping as a distance in centimeters and based of that distance set the DC motor to a defined speed. The PWM output goes to a 210 Ohm resistor connected to the base pin of a transistor, on the collector/emitter is the 18V circuit connected to the DC motor. On a separate circuit is the arduino and ultrasonic sensor.

The circuit successfully gives me accurate distances in the serial monitor window. However, the motor only goes at 100% speed. It does not throttle its speed regardless of the distance variable's value.

It startles me that the default motor speed for this setup is 100%, it makes me think the speed is acting digitally. I tried deleting the final elseif conditional for the distance being greater than 45 cm set speed at 100% and the circuit still powered the motor at 100%.

Any help would be greatly appreciated!


texts:
I would like to know if it is possible to remap a single pin of a multi-pin (SPI) peripheral?

For instance, I have a STM32F107 and I want to use UART4, SPI3 and Ethernet.

PC10 = UART4_TX - Remap function = SPI3_SCK

PC11 = UART4_RX - Remap function = SPI3_MISO

PC12 = UART5_TX - Remap function = SPI3_MOSI

PB3 = SPI3_SCK

PB4 = SPI3_MISO

PB5 = Ethernet or SPI3_MOSI - I have to use ethernet.

What I want to do is to use PC12, PB3 and PB4 for SPI3,
and then use PC10 and PC11 for UART4.

Is it allowable to only remap one pin and not the entire peripheral?

I would like to use the HAL libraries to configure, if possible.


texts: Serial DC-link Capacitor to increase the effective voltage rating

texts:
I am developing a 2-phase motor driver system, which requires my inverter's DC-link to be near 480V. 480V is used to generate 2 line-line voltage of 220Vac(using 3-phase inverter).

The Aluminium capacitor at 650V are too expensive and bulky. I am thinking of serially connecting the capacitor with added voltage margin to account for unbalanced voltage sharing. Is using 2 400Vdc Al cap in series a good idea ?

EDIT: So as suggested, I can balance the voltage across the capacitor using parallel resistor. How should I calculate the value of the resistor.

simulate this circuit – Schematic created using CircuitLab


texts: will there be any difference between the output of a 555 oneshot and one made with a 74123?

texts:
I think there won't be any difference because the professor wants us to build both with 10 us pulse and with a duty cycle of 25%.

I didn't have enough time to build both MMV, so that's why I am asking


texts: Which files to version control for an Altium PCB project?

texts:
I'm trying to create the .gitignore file for an Altium project that is versioned with git and stored remotely on GitHub.

I don't want my teammates to continually struggle with having to update every single time I make a small change, like re-run design rule checks or re-compile the project. What are the minimum files I should I add to my version control system?

# Ignore the subdirectory where output job outputs are placed
GeneratedOutput

# Ignore autosave files (anything that begins with a tilde)
~*

# What else to ignore?


texts: Can I generate pulse with timer1 in normal mode in ATmega 2560 using TOV flag?

texts:
Timer have CTC and PWN for generating pulse. However if I want to generate pulse when timer reach its max level then using CTC or PWN is somehow not needed when the TOV is set whenever timer overflown. My idea is that the output pin will toggle whenever the TOV flag is set then TOV flag is cleared and wait for another overflown of timer. Here's my code in C though I not sure because I haven't understand how to handle each bit in register yet and I don't know how t simulate it in proteus.

#include <avr/io.h>
int main(void)
{
    TOV1 = 0; // clear timer 1 overflown flag
    DDRD = 0xFF; // set port D as output
    TCCR1B = 0b00000001; // using internal I/O clock with prescaler 1
    while(1){
        if (TOV1 = 1){
            PORTD ^= (1<<PORTD0); // toggle bit 0 on port D
            TOV1++; // clear TOV by adding 1 to TOV
        }
    }
}


texts: Is it possible to charge a laptop with a DC-DC converter using a 12V deep cycle battery

texts: Am just curious if I can use a DC-DC converter and 12v deep cycle battery to power a laptop directly.


texts: High-side vs low-side reverse polarity protection

texts:
I need to make a reverse polarity and over-voltage protection for a fairly powerful device (45W @ 12V input) and after some research I noticed a weird peculiarity. A typical reverse polarity protection circuit is shown below; it uses a p-channel MOSFET in a high-side configuration as a switch.

N-Channel MOSFETs tend to have lower Rdson, they are much more common and usually cheaper, so, as I guess, using a N-Channel MOSFET is preferable. The same schematic also exists with a N-Channel MOSFET, but to put the N-Channel MOSFET in a high-side switch configuration a charge pump or some other type of dc-dc inversion is required (second schematic).

But why not just put the N-channel MOSFET on the low side like on the third circuit? For some reason I've never seen in any device I've put my hands on a protection circuit with a low-side protection. So, my question is:

Why is it preferable to put the protection switch in the high-side configuration rather than the low-side?

*This peculiarity carries onto the over-voltage protection as well. The PMP10737 TI reference board, for example, uses a P-Channel MOSFET for the overvoltage protection; however, to prove my point that N-Channel MOSFET are better for this purpose, the same board uses a N-Channel MOSFET with a complex IC to drive it in the reverse polarity protection! *

simulate this circuit – Schematic created using CircuitLab


texts:
i want to model a cascaded Buck/Boost-Converter with FAST like mentioned here: https://cbasso.pagesperso-orange.fr/Downloads/PPTs/Chris%20Basso%20APEC%20seminar%202013.pdf.

The goal is to implement a controller, to verify constant Voltage at the Output:
\begin{align}
V_{out}=355V.
\end{align}
The Power will be:
\begin{align}
P = 3.6kW,
\end{align}
so the Resistance at the Output is:
\begin{align}
R_L = 35 \Omega.
\end{align}

The Topology looks like this:

My Question is how to model the the Converter in consideration to the Output-Voltage and the Resistance?

I would think I should model my known Values for the Output-Voltage like this:

or is it easier to model only the Converter Dynamics without these parameters?

edit: another Question is, if i can make an order reduction in case of the Voltage over C1 is equivalent to Uin?


texts: How does doubling the voltage amplitude change the decibels?

texts:
Suppose I listen to some music on my headphones. Now change the amplitude (in volts, as measured e.g. with an oscilloscope) of the audio signal by a constant factor G.

Assuming that the amplifier in question is linear in the region we are talking about, how does this change the audio signal's power in dB, the loudness in dB(A) and the sound pressure level in dB?


texts: how to step down both voltage and current for high power

texts:
I have looked at Buck converters, voltage dividers, and current dividers, but I have not found a way to divide, BOTH, voltage AND current + being able to do it over high voltages and currents.

With voltage dividers, voltage is divided, but current remains the same.
With current dividers, current is divided but voltage remains the same.
With buck converters (as far as I know), the voltage goes down, but the current goes up.

How do I efficiently divide both voltage and current over high power?
EDIT:
I don't want to be limited to dividing the voltage and current equally, I just need to be able to divide both.
This is for a 14lb robot. I have 4 Battery packs for each of my Wheel Motors. I want to connect them in series, then step down the voltage and current down to a voltage/current that an Arduino can handle.
I have 48v, 80A power. I want to divide the voltage by 10.7, and at the same time, divide the current by 2670 resulting in 4.5v, 30mA for the Arduino board.
Please answer with a simple schematic diagram with your post.


texts:
In books, I have studied that in a Transistor, the Base is the layer sandwiched in between Collector an Emitter. Wikipedia also mentions that
"The base is physically located between the emitter and the collector and is made from lightly doped, high-resistivity material. The collector surrounds the emitter region, making it almost impossible for the electrons injected into the base region to escape without being collected"
something like this-

But the images of Transistor dies I found had completely different construction.

The bond wires are connected to the Base and Emitter and the Collector is underneath the two layers. The Base and Emitter seems to be on the same plane and Base is not sandwiched in between as said in books.
Then how is Base physically located between Emitter and Collector?
And if not, then how does the die work as transistor?


texts: Please help me identify two pin locking connector

texts:
This is a two pin, locking style connector with "AMP" molded into the front edge; there is also a "P".
Material is nylon or similar and the pins are pushed in from the rear like Molex connectors.
What is "unusual" is the D shaped profile of the "nose" - close but not compatible with other two pin connectors I can easily obtain :(

AMP/Tyco never got back to me and our usual distributors are clueless.
We have a few thousand machines in service with 24 volt power supplies that use this connector (manufacturer of the power supplies is HIPRO - now under new ownership - also not communicating)

Have spent a week trawling through connector catalogs, waited a couple of weeks for Tyco and the power supply folks to get back to me... a bit frustrating.


texts:
Today I had a luck to kill my STM32F3discovery through connecting pin to +18V and this trouble made me think about protection from such situation in the future. I've found this protection of inputs using diode and zener diode.

So, I'm wondering about such protection for protection pins in such cases:

Input pins, low spees(like a button)
Output pins, low speed(like a led)
Input pins, high speed
Output pins, high speed(especially, PWM)

Maybe someone knows integrated solution?


texts: Detecting HI-Z state of charge controller

texts:
I have been building a Li-Ion charge controller with MCP73831. The STAT pin has 3 states as shown below:

The circuit I come up so far is this:

Is there a way to detect the HI-Z state with another transistor and an LED?


texts: What is clock skew, and why can it be negative?

texts:
My HDL compiler (Quartus II) generates timing reports. In it, the nodes have "clock skew" column. The only definition of clock skew I found is in the TimeQuest documentation (see page 7-24):

  To manually specify clock uncertainty, or skew, for clock-to-clock
  transfers, use the set_clock_uncertainty command.

So if skew is "uncertainty", why are some of my clock skews negative (e.g. -0.048)? What exactly is clock skew?


texts:
So I understand that LED's have a maximum current (like 20mA for instance), but scientifically why is this?

Using the water analogy it seems like a high voltage would be the thing that would mess up something (I like to think of it like a huge amount of "pressure" blowing out a pipe or something). Why would a rate of electron flow damage something?


texts: Changing current limit on a cheap BLDC motor controller

texts:
These are my options:

250 W, 12 - 24 V, no A information, assuming 250/12≃20 A
500 W, 12 - 36 V, 15 A

If used with a BLDC motor of lower power with lower maximum allowed current, what are the chances that such a controller can be easily tweaked to lower the max current limit? (e.g. replacing a resistor with a different value)


texts: How come one type of DC motor could have different resistances?

texts:
Looking at some DC motors, a single type could have a range of resistances:

It appears that lower resistance results in higher pull-in torque. If that's the only change, wouldn't a low resistance motor always be desirable? Why would one want a high resistance, low torque motor over a low resistance, high torque one?

Any thought appreciated.


texts: Get more AS-attached flash chip information from ALTASMI

texts:
I am playing with the attaching various configuration flash devices to the Altera Cyclone 3. In particular, I want to replace EPCS16 (2MB) with W25Q128 (16MB) - for both size and cost reasons.

Is seems that Altera/Intel does not like people doing this; and there's scarce information about command set accepted by the EPCS devices - I suspect there're more commands than listed in the datasheet. I also read at some other place that EPCS devices are just relabelled devices not made by Altera (as they do not make flash devices for quite a time).

Anyway, datasheet would be very useful when you want to develop your own configuration flash interface IP; at this point I am using ALTASMI_PARALLEL which seem to work properly with W25Q chip.

However this megafunction only allows reading silicon ID (command 0xAB, read_sid), and device identification (command 0x9F, the "capacity ID" part, read_rdid). Both requests work for me using ALTASMI, with SID returning 0x14 (EPCS16) and RDID returning 0x15 (2^21 = 2MB).

Comparing EPCS and W25Q datasheets, I see that both chips report 3 bytes for the command 0x9F (command is called JEDEC ID), but EPCS datasheet says that first two bytes are "dummy". These bytes are expected to hold manufacturer ID and upper 8 bits of device ID.

I suspect EPCS device returns something within these bytes; but Altera did not bother to implement them fetching from the ASMI megafunction as they expect (or want/force) developers using their branded EPCS devices.

Looking to the files created by megafunction I see instance of asmi_altasmi_parallel_pio2_component, only 8 bits of which are used as RDID, and I am unable to find any further infomration (for example, may this submodule be returning 24-bit vector, not only 8 used by ALTASMI module?) this module in the same "asmi" file created by the megafunction :).

Anyone had been dealing with such issue? Reading full JEDEC ID would help definitely identify the flash chip attached.

The good thing is that, with current implementation, I still have capacity ID returned by RDID command, thus at least can know the size of flash (I need it because its first 512K must be write protected). All other info identifying exact chip is not critical and a kind of "cosmetic" just to display it on the screen (at least I do not see how I can use/apply it within current environment).

P.S. Alteraforum migrated to Intel forums. There were more or less independent people there sharing their knowledge, now I get business-protective replies like "not supported" or "you are fool customer". That's why I ask question here in hope there're still independent experts around!


texts: Transient and steady state of marginally stable system

texts:
I know that if a system is asymptotically stable then after infinite time its output contains only characteristic of input signal and it is also known as steady state and there are no transient component left in output, and if system is asymptotically unstable then whatever will be input is its output will become infinite after infinite time so we can say that it doesn't reach at steady state and it's transient components become infinitely large
but what about transient and steady state in marginally stable systems?
Because in marginally stable systems even after infinite time it contains both inputs characteristics and systems characteristics so what exactly transient and steady state components will be?
I don't know whether I understand transient and steady state conditions properly (whatever I explained above) or it is just poorly defined in books?


texts: How to calculate Gas sensor PPM from analog readings?

texts:
I am new to Arduino and electronics in general.I am working on MQ 7 Gas sensor to test Carbon monoxide level. But the issue is i still can't grasp the concept of converting analog readings to PPM. I tried to follow this ,but some parts, are very clear especially R0 = RS_air/(26+(1/3))

So far with my code below the ratio  I get is between 20 and 30. Can someone help me complete the PPM calculation or point me in the right direction.Here is the Data sheet

Thank you in advance

int gasAnalogPin = A0;

void setup() {
  Serial.begin(9600);

  pinMode(gasAnalogPin, INPUT);

}

void loop() {

 float sensor_volt;
 float RS_air;
 float R0;
 float sensorValue = 0;

  // A) preparation
    // turn the heater fully on
    analogWrite(gasAnalogPin, HIGH);
    // heat for 1 min
    delay(60000);

    // now reducing the heating power: turn the heater to approx 1,4V
    analogWrite(gasAnalogPin, 286.72); // 255x1400/5000
     // heat for 90 sec
    delay(90000);

  // B) reading
    // CO2 via MQ7
    analogWrite(gasAnalogPin, HIGH);
    delay(50); // Getting an analog read apparently takes 100uSec

  for(int i = 0; i <= 100; i++){
    sensorValue = sensorValue + analogRead(gasAnalogPin);

   }
 sensorValue = sensorValue/100.0; //get the avarage value
 sensor_volt = sensorValue/1024*5.0;
 RS_air = (5.0-sensor_volt)/sensor_volt;
 R0 = RS_air/(26+(1/3)); // Not sure how they came up with this ?

 float RS_gas = 0;
 float ratio = 0;

  sensor_volt = 0;
  sensorValue = 0;
  sensor_volt = 0;

  sensorValue = analogRead(gasAnalogPin);
  sensor_volt = sensorValue/1024*5.0;
  RS_gas = (5.0-sensor_volt)/sensor_volt;
  ratio = RS_gas/R0; //Replace R0 with the value found using the sketch above

  Serial.print("PPM:"); // How to calculate PPM?

}


texts: Altium - IDF importer doesn't recognize components with E* or H* designators

texts:
I am trying to do the following:

I have created an IDF file (.emn) with details about where certain components should be placed, the shape of the board, keepout areas etc. and I'd like to import the information of the file to the Altium PCB.

But the problem is that somehow the components whose reference designators starts from E (that would be SFP cages at my design) or H (that would be LEDs) are not recognized and are not imported.

The connectors (which at my design have designators starting from X) and dip-switches (from S) are perfectly imported and placed.

Does anyone know how can we change the designator names that the importer understands? I haven't found any similar settings.


texts: Wire to wire connector for multiple DC outputs from single input

texts:
I'm wondering if anyone is aware of a connector that I could use to distribute a single 5v line into many devices such as the picture below:

simulate this circuit – Schematic created using CircuitLab

I'm sure that there would be something similar that is used in computers for this purpose but I am basically trying to avoid creating a PCB or having a connector with multiple wires coming out of a single pin.

To clarify: I'm looking for a relatively small wire to wire connector.


texts: Can anyone explain the function of this op-amp in a Velleman Clap On/Off Switch?

texts:
I am currently working on this project for a clap on/off switch by Velleman (MK139). I am trying to analyze this circuit and I noticed one thing. In the circuit diagram for this device, you can see the op-amp component IC1C at the midsection of the diagram. What I am trying to figure out is why exactly this op-amp isolated with only a connection to ground?

I have no possible idea other than that the entire midsection is an audio amplifier (please correct me if that's not accurate) that helps convert the sound waves from the mic to an electrical signal.
Thanks so much for anyone's advice or input!


texts: Bad Headphone Connector Wiring Issues - What Could Be Wrong?

texts:
I am trying to repair a headphone cable with a splice. The audio sounds really bad after the repair. I can hear instruments, but not the vocals. Also, the playback is mono, same sound on both sides.

If I short Left to Right, the audio gets quiet, but still sounds bad. If I short Left to Common, or Right to Common, the sound quality returns to normal, but audio playback is still mono. Does this mean there is a open connection on common, and a short between Left and Right? Or is some other fault possible?


texts: How to convert Sequential circuit into a combinational circuit?

texts:
My question in general asks how to transform a sequential circuit/FSM into a combinational circuit.

The reason why I'm asking is in SAT solving, we can use only combinational circuits. And so in order to use sequential circuit, we need to "unroll" them into a combinational circuit. I don't quite understand this.


texts: About Microcontroller having many SPI controllers

texts:
I would like to ask if anyone had an experience of using more than 1 SPI controller/channel on a project? I had this pyboard where it has up to 3 SPI controllers though i think only 2 SPI controllers can be used. This is different from the traditional multiple SPI slave scheme which is applied on 1 SPI controller only.

I had this setup where 1st SPI controller (SPI_1) will talk to a SPI-based relay hub and the 2nd SPI controller (SPI_2) will talk to multiple SPI-based sensors. Now my question is, can this two SPI controller operate simultaneously or at the time, SPI_1 will turn on & off relay(s) while SPI_2 will read sensor values. These two generate serial clocks different from one another right? Can this be achieve? also how would this be applied on the programming side?

I had many experiences on SPI using arduino boards but i haven't yet try using two different SPI drivers at the same time since arduino boards does only have 1 SPI driver.

EDIT:

http://www.st.com/content/ccc/resource/technical/document/datasheet/ef/92/76/6d/bb/c2/4f/f7/DM00037051.pdf/files/DM00037051.pdf/jcr:content/translations/en.DM00037051.pdf is the microcontroller used by the pyboard v1.1.

https://docs.micropython.org/en/latest/pyboard/pyboard/quickref.html#general-board-control is the board i'm going to use.


texts: MOSFET in cadence is symmetric? Source and drain don't really matter diagramatically

texts:
I am doing an OTA in cadence and I accidentally was using an upside down NMOS MOSFET. What I mean by that is that considering lower voltages are on the bottom of your circuit, then the arrow that goes out of the nmosfet (the source) was on top instead of on the bottom.

It turns out my simulations are almost exactly identical to the corrected case where the diagram's source is on the bottom.

So my question is: does it really matter which terminal is used for source and drain? Maybe it does because source and drain terminals are doped differently but maybe the mosfet is completely symmetric.

In the image look at transistor M14 on the right side.


texts:
Ok, so I know that the intensity of the light given by an LED is the minimum it can be at the turn-on voltage, however I don't know if the wavelength of the light emitted from the LED at the turn-on voltage will be below the peak wavelength (the wavelength at which the intensity of the light of the LED is at its maximum) or above it. My reasoning comes from the picture below:

The picture shows that for a specific colour of LED, for any intensity instead of the peak intensity there can be two wavelengths associated with it. For instance, for the blue LED, there will two values for wavelength for when the intensity is 20%. So, my question is: Is the wavelength of the light emitted from an LED at its turn-on voltage greater than or less than the peak wavelength of the LED?


texts:
I have been thinking about using EL wire in our house as a night light but I am concerned about electromagnetic compatibility and possible adverse effects on the inhabitants (we).

You can see these EL wires driven by cheap chinese inverters. So given that the operating point typically is at 100V(AC), 1kHz, 100mA (and I am probably going to use several EL wires), I think the EMC concerns might well be justified.

But I just can't find anything about EMC/biocompatibility and EL wires. There are YouTube videos of people innocently wearing EL wire close to their body (of course there is no immediate harm if the inverters have proper current limiting, but probably something mure subtle like cancer risk in 10 years or something), and the thought of having 100V close to my skin makes me a little uneasy. There are also videos where you can literally hear the inverter buzzing.

Are there any investigations about the topic? Which EMC regulations could apply? Are there probably directives regarding the use of electroluminescence in medical devices?

Sorry for being so unspecific, but I honestly don't know where to begin in order to judge whether it is advisable to have EL wire operating near your family.


texts: Why does adding one more extension cable turn the MCB on again?

texts:
I found a strange phenomena when I tried to use a metal cutter that consumes about 2000 watt.
See the following illustration.

If I just use one extension cable, the MCB will trip when I turn on the cutter. However, if I add one more extension cable, everything is just fine (the MCB does not trip). It looks strange to me. Why does it happen?