texts: Reference clock of 400 MHz oscillator or 20 MHz and multiply by 20?

texts: I am trying to design a sinusoidal signal generator using AD9954 which is a Direct Digital Synthesis (DDS) with takes a maximum of 400 MHz crystal oscillator as reference frequency. It also has a register that can be written for multiplication so that a lower crystal oscillator at 20 MHz for example, can then be multiplied 20 times to get a 400 MHz reference frequency. My Question - is it better to use a crystal oscillator that provides 400 MHz or use a lower frequency such as 20 MHz and then multiply it? Which one would be more efficient? I found a few posts on here such as this but tit did not answer my question.


texts: What is white powder on component leads?

texts:
I can't post a picture, since I don't have a good camera.

I've noticed white powder on leads of some components. What could it be?

I'm sure that it isn't just dust, because there isn't any on the component bodies and was on some components which were stored in their own sealed bags.

I've seen it on all types of components, but not all components have it. I was unable to find any mention of it in any datasheets. I've seen in on for example Fairchild DB237 transistors, Piher potentiometers, various no name resistors and so on.

I did notice that most components which have the powder have flat leads.


texts:
I was looking at datasheets of the 7808 and 7908 regulators from STMicroelectronic.

The mystery for me is why positive voltage regulators have capacitors without polarity (for example ceramic capacitors) and negative voltage regulators have capacitors with polarity (so electrolytic) and also why sizes of these capacitors are different.

Schematic for 7808 is:

Schematic for 7908 is:

I also found a schematic for a +-15V power supply in one of these datasheets where capacitors sizes and types are also different:

Thanks in advance


texts: Is there an electrical component for something between a button and force sensor?

texts:
I'm currently involved in a college team design project and we're creating a "dance" floor that can be switched on and off by stepping on a plexiglass tile.

I'm looking for the best way to gather an input from the floor button.  We tried using a floor switch which is built to take the weight, but the travel of the button worried me, as more moving parts means more things can go wrong.  Our prototype.

I tried doing something simpler by using 4 regular small buttons.  This worked somewhat well but I don't think it would take weight very well.

I looked into other solutions - a flat force sensor (with no moving parts) seemed like a great solution - but they are relatively expensive compared to buttons.  They also are analog.  Although we can use an MCU to convert it into a simple "on/off" I'd prefer to avoid that.

I also looked at piezoelectric components.  These seemed like the best bet, but again are analog and can produce a noisy signal.

Is there something like a no-travel, flat, resilient and cheap switch?  Is there something like a force sensor but as a simple pushbutton digital switch?

Apologies if this is the wrong forum but I'm feeling a bit lost searching through the endless tables of DigiKey.


texts: Phase Difference Between Two Signals (Problem)

texts:
I am asked to calculate the phase difference between the two signals below.

$$i_1 = -4\sin(377t + 55^\circ) \hspace{0.2cm}\quad \mathrm{and}\quad \hspace{0.2cm} i_2 = 5\cos(377t - 65^\circ)$$

What I did was to convert $$i_1 = -4\sin(377t + 55^\circ)$$
to
$$i_1 = 4\cos(377t + 145^\circ)$$

Then find the difference by $$145 - (-65)=210$$
Then we conclude $$i_1\hspace{0.2cm} leads \hspace{0.2cm} i_2 \hspace{0.2cm}by \hspace{0.2cm}210^\circ $$
But, let's add 360 to (since the result won't change)
$$i_2 = 5\cos(377t - 65^\circ)$$
We get $$i_2 = 5\cos(377t + 295^\circ)$$

Now comparing the two we get difference to be 150 degrees,which means
$$i_2\hspace{0.2cm} leads \hspace{0.2cm} i_1 \hspace{0.2cm}by \hspace{0.2cm}150^\circ $$

My questions are that,

What is the difference between these two answers? Is the latter wrong?
How can both lead?
How could we rewrite the second answer in terms of i1 leading i2?


texts: EEPROM returns 0 while trying to read anything

texts:
I'm using a CC2652r to try to read and write to an MX25R8035F EEPROM using SPI.

I'm using the build in SPI driver to try and communicate with the EEPROM but  while the drivers says it succeeded the transfer of data, the data I get back seems to be 0 at all times.

For example if I try to use the REMS (read electronic
manufacturer & device ID) to get the manufacturer & device ID I send 4 bytes containing 0x90, 0xFF, 0xFF, 0x00. But instead of getting 0xC2, 0x14. I'm getting 0x00 and 0x00.

I initialize my SPI with:

    /* Open SPI as master (default) */
    SPI_Params_init(&spiParams);
    spiParams.dataSize = 8;
    spiParams.bitRate = SPI_BIT_RATE; //(4000000)
    spiParams.frameFormat = SPI_POL0_PHA0;
    masterSpi = SPI_open(MX25_EEPROM_SPI, &spiParams);
    if (masterSpi == NULL) {
        System_abort("Error initializing SPI\n");
    }

Then in a Task I try to get the electronic manufacturer & device ID with:

//BLS_CODE_MDID = 0x90
    uint8_t wbuf[] = { BLS_CODE_MDID, 0xFF, 0xFF, 0x00 };
    SPI_Transaction transaction;

    // Configure the transaction
    transaction.count = sizeof(wbuf);
    transaction.txBuf = wbuf;
    transaction.rxBuf = NULL;
    extFlashSelect();
    uint8_t ret = (uint8_t) (!SPI_transfer(masterSpi, &transaction));

    // Configure the transaction
    transaction.count = sizeof(infoBuf);
    transaction.txBuf = NULL;
    transaction.rxBuf = infoBuf;

    ret = (uint8_t) (!SPI_transfer(masterSpi, &transaction));
    extFlashDeselect();

Where extFlashSelect put the slave select pin low and extFlashDeselect put it to high.

I also tried setting the rxBuf and the txBuf in the same transaction but got the same result.

I hope someone is able to help me with this.

EDIT:
I tried specifying the frame format in the parameters passed to SPI_open.
According to the documentation of MX25R8035F, CPOL 0, CPHA 0 and CPOL 1, CPHA 1 together should be supported but the result is still the same.


texts:
First, I'd like to note that I'm a software engineer by profession and haven't had anything but trivial experience in interfacing with hardware.

With that said, I'm looking at getting a prototype going with an electrical engineer.

Basically, we have an RN-171 WiFi module that we need to communicate with an iPhone.

I'm not sure why the exact module was chosen as it's made to connect to WiFi network and GET and POST information to it. We want to use it differently however, we want it to broadcast a network in Adhoc mode and connect an iPhone to it which was trivial.

The next step is, once the iPhone is connected, we need to be able to retrieve data from the device. The device is hooked up to a microprocessor which is hooked up to some monitoring devices. The idea is, the device saves monitoring data to a memory card, a user comes along and wants to check the logs, so he connects to the Adhoc network using his iPhone, sends a request to the RN-171 which then somehow sends a message to the microprocessor asking it to send through the log data to the iPhone over WiFi (can't assume there will be any other device other than the iPhone and can't assume a 3G network is available).

The thing is, the device isn't programmable as far as I can tell so I have no idea how I can achieve that. To be honest, I don't care how the RN-171 communicates to the iPhone.

I noticed that port 80 was open so I tried to access the device through the web browser but all I'm getting is an empty screen and I don't think there's any way to get it to display any info (although it would be good if I could...).

The device also interfaces over port 2000 so I connected to it via that port using telnet and could see messages from my laptop connected to the device (which I'm testing with) but I could figure out, again, how to send it to send messages to the device.

I did realize, however, that there is a command set comm remote <message> where message can be a 32 character long string of choice. So far that looks to be my best way to communicate to the device (assuming ios can talk to the device over port 20) that I've found which is pretty sad. Basically, I'll have to connect and disconnect from the port, each time receiving up to 32 length of character data which sounds ridiculous.

So yeah, it may be quite obvious that I don't have much idea where I'm heading so any information will be very appreciated as to where I can go from here and what my options are using this device.

EDIT: The issue is how to communicate from the device to the iPhone. The remote message I mentioned is shown up when a TCP connection is established to the device. For example, if I set the message to TEST, when I telnet to the device over port 2000, I'll get back TEST. Obviously this isn't meant to be a way for the device to communicate data to a device connected in Adhoc mode.

The ideal scenario is when the connected device makes a HTTP request to the WiFi device, I get back some custom infomation (for example a table of data). If not, then any other method of communication is okay. Basically I want to know how to communicate information from the WiFi device to the iPhone when the iPhone requests information.


texts: Allegro ACS71020 unable to read voltage SPI register

texts:
Hi I'm trying to read from the registers of the ACS71020 over SPI, but I can't seem to get any values other than 0. The only time I am able to get anything other than 0 on the MISO line, is on the address: 0x0C and the response has to do with some error code called "No meaning". I'm defaulting the CS line to high then setting it to 0 during the transaction (I think this is the correct way to do it because I haven't even gotten an error message using the opposite way where the default is "0" and then during transaction we set to "1". It literally feels like the chip does nothing in this scenario).
I've attached two images. The pink color is the sclk in both images. The blue color is MISO and the yellow color is MOSI. I am sending 7-bit address 0x20 with read bit (high) after. You can see that the blue (MISO) line gives me only 0 as response.

What could I be doing wrong here?


texts: How much current do you require in Arduino and embedded systems projects?

texts:
How much current do you require in Arduino/Sanguino or other embedded
systems projects?

After responding to the LM2575 inductor question I started to take
a closer look at the TI power DC-DC converters. It would not be
difficult to replace the linear regulator + or'ing diodes on all
my Arduino/Sanguino compatible boards with a TI step-down converter.

This would provide a >90% efficient conversion, input voltages from 5-15V
and a 2.5A output that is regulated and adjustable. What would be
sacrificed would be the ability to power off of the USB. The incremental
cost would be in the $5-$8 range. Wider range inputs are also
possible.

Is the 500mA you can get from the USB port all you ever need?
Would this be useful in your projects or is it too little current?


texts:
Further to my two, other questions about Zener diodes to detect when an automotive battery is being charged by the alternator, I've developed the following:

Note: The Fritzing tool I used doesn't have a breadboard symbol for a 10-14v supply, so I've used a battery symbol to make clear which my positive and ground rails are.

The schematic looks like this:

My main question is, is this circuit correct?

If I understand things correctly, (unfortunately not the results I am seeing in the real world):

The Zener diode should break down at 12v, it doesn't - it's always letting through < 0.1v regardless of the input voltage in the range of 1-12v. Past 12v there's a marked increase in the throughput of the zener diode, consistent with what one would expect.
It's not immediately obvious from the data sheet whether I should wire my reference, or the variable source to the - or + of the LM311. I've done it the way below.
I'm told, as this is an open collector IC, I need a pull-up resistor to

I also have some questions:

How can I calculate how much power this circuit will use "at rest", i.e in order to do almost nothing until the alternator is running, without placing a demand on the battery?
Is this the only/best way to detect a running alternator?
Given that my reference is 1.26v from the rechargeable button cell, I will eventually need to connect something to recharge that when the system is running.

Lastly...

Where does one find a freelance electrical engineer who could design such a circuit to a list of constraints and produce a simple schematic/PDB that meet the requirements?


texts: Organic Material Impedance and Needed Power Requirements

texts: I'm attempting to determine the power requirements to essentially boil/burn long running, deep weed root systems similar to the tech used by https://rootwave.com/technology/. I'm in the beginning stages of such an endeavor, as an amateur in electronics my thoughts on what step to take first is to determine the impedance level of said root type I'd like to boil/burn before determining power requirements. Is this the right approach? If so, given said impedance (TBD) how do I then determine power needs to reach a level sufficient enough?


texts: get 100mA pulses from 20mA source to charge li-ion

texts:
I have only 20mA in my circuit and after trying to charge a battery with TP4056 it doesn't work. TP4056 is a linear charger so I need to try with LTC4002 or even better to improve efficiency. Anyway, my first attempt was to implement a charge pump like this:

My goal is to obtain 100mA or more (8v) pulses from 20mA @ 8V input. To do this, I used a supercapacitor connected to a hysteresis comparator so when Vcap is >5V output is enabled, so pulse can be done and feed the li-ion charger, and when Vcap is bellow 1V this output is disabled so supercapacitor can charge again.

This is the schematic:

(Some resistor values was changed over the tests...)

and this is the expected output:

I tested it with a load and circuit seems to be successfully enabled, but if load is present seems like is not able to disable comparator output and some weird waveforms happens.

Maybe this schematic is not the best approach to solve the problem: any suggestions?

------- EDIT -------------------------------------------------------------------

This power supply is for a GSM device with peaks of 2A but average of 60mA. The device will sleep some days and some hours a day, so can be "recharged" in this moments. Supercapacitor can do the job of charge/discharge, but since consumption is higher that the one who a supercapatitor can give, I considered a battery.

Solar chargers have similar pulsed charge currents, but higher than mine.


texts: I’d like the 12v rocker switch LED to illuminate when the switch is turn OFF

texts:
I've exhausted a google search and am hopeful expertise on this board can help me with my objective.

My Arcade has LED lighted buttons when the cabinet is on. The LED button lights are powered by a dedicated 12v 3amp power source.

My objective is to install a 12v rocker switch to allow me to turn on/off the power to these LED lights.
HOWEVER, my goal is to have the light on the rocker switch illuminate when the switch is in the OFF position, and NOT illuminated when the switch is in the ON position.

I would greatly appreciate guidance if this can be done. If so, does this require a "special" switch, or is it as simple as reversing any of the wires. If it requires a special rocker switch, would you have a URL link where I may purchase one.
My google search for "12v LED illuminated when switch is OFF" comes up empty.

Thanks in advance,


texts: Magnetic force as a function of PWM frequency

texts:
Consider an experiement with a DC source feeding an coil with a constant DC current I. The coil with an iron core attracts a magnetic plate with mass m with force F. The force F is higher than Fm and the plate is kept in place. Now the DC source is substituted with a PWM controlled output. Say with duty cycle 50% and a DC level leading to same rms current A. What will hapen if the frequency of the PWM is increased?

A) Nothing, a PWM with same duty cycle at 1kHz, 10kHz, 100kHz or 1MHz still create the same magnetic force still lifting the plate.

B) There will be a maximum frequency where F=Fm and the plate will drop off if frequency increased further.

I'm trying to understand if sudden releases and issues never seen before in an industrial process could be related to the fact that new type of HW has increased PWM frequency from <10kHzish to ~100kHzich could be the root cause. Current levels are measured by fast clamps and at same level. Voltage at 110VDC same as before. Also very interested in the physics behind if it one would run some simulations around it.


texts:
if an opamp is having +15/-15V rail to rail voltage, is there a way to determine how much will either of these power supply get loaded? will they get loaded equally?
what happens if I use +18, -12V rail to rail voltage?


texts: Measuring a small distance via capacitance

texts:
I am interested in measuring a small \$d\$ between two objects shown below by measuring the capacitance between the Terminals denoted as T0 and T1:

The distance \$d\$ is roughly 1mm +/- 0.5mm large. In this case, the capacitance should be given by (\$r\approx 6.5\mathrm{mm}\$ is the radius of the base of the cone).

$$C=\frac{\epsilon_{0} \pi r^2}{d} \approx 1.2\mathrm{pF}$$

My idea is to measure the distance with the following setup:

simulate this circuit – Schematic created using CircuitLab

If the current and voltage are 45° out of phase at a frequency \$f\$ we have that:

$$\frac{1}{\omega C_d}=\frac{d}{2 \pi f \epsilon_{0}r^2\pi}=R_1$$

From which \$d\$ can be determined. I have the following questions regarding this setup:

Is it ok if I solder two small "pins" on the two objects (cylinder and cone) and simply connect the wires from the 30MHz signal generator via alligator clips?
(I'm using a "BNC-To-Banana" adapter like this one here: link adapter example and the generator has a 50Ohm output impedance).

My main question here is mostly whether I need to pay attention to any parasitic quantities (capacitances/inductances) or other things which might affect the precision of the distance measurements?

Update

I know did this measurement using the setup shown in the following picture (I used a 1MOhm resistor and the gap is around 2mm):

I'm using the following circuit:

simulate this circuit

The issue is that if I set the frequency of the function generator in the range of 200kHz and 10MHz \$f \in [0.4,10]\mathrm{MHz} \$ I am only measuring voltages of around 100mVpp over the resistor (with an input voltage of around 3Vpp [peak-to-peak]). At 10MHz I have that:

$$Z_{Cap}=\frac{1}{2*\pi*10^7\mathrm{Hz}*2*10^{-12}\mathrm{F}}\approx 8\mathrm{kOhm}$$

So basically at 10MHz, the voltage over the resistor should be approximately equal to the input voltage but I'm measuring only a very small voltage over the resistor, see the plots below (note that on the bottom left plot, I use another voltage scale to show that there seems to be a slight phase shift between input voltage and voltage over the resistor). The colors in the oscilloscope plots are the same as the colors on the photo of the measurement setup.


texts: AD623-Unable to change gain or reference voltage

texts:
I have an air flow sensor (FS1012-1100NG) with expected differential output voltages ranging from -1mV to 20mV and I need to 1) know the precise value (mV) and gain to correlate V with airflow 2) make sure that value has long-term stability (order of days) and 3) end up with a voltage that makes the best use of my 12bit ADC.
I'm using an AD623 with a single supply (3.3V) with the FS1012 connected per the datasheet (see image).

pins 1&8 Gain Resistor (I've tried 100ohm-1Mohm but no change in output/gain)
pins 2&3 TP2+ and TP1+ (I've checked these and there is a differential voltage of about 2-3mV at max airflow)
pins 4&7 Ground and 3.3V
pin 5 Ref (Tested 0-3V using voltage divider, no change in output/offset)
pin 6 Output (to digital multi-meter with ref to ground)

What am I doing wrong? Is there a better differential amplifier I should be using?
Thank you in advance!


texts: The effect of the increase in the number of transistors in a chip on a processor's peformance

texts:
everyone.

I am doing a research on assessing the degree to which the number of transitors in chips affects the processor's performance in a certain environment.

Of what I understand this far, in order to get the experimental data I need to use/make comparisons of different processors. My topic I understand - I should probably only focus on the performance difference and not so much heat dissipation. So, in order for me to be able to compare two processors' performances according to their transistor count, I would need to use data from testing of processors with the same architecture? I assume that I would need to choose data, where they test them in the same performance evaluation environment and workload, when conducting the comparison? Let's say a computer game ( I believe such benchmarks are published frequently).

When analyzing the difference, how is it possible to know how much of it is due to the transistor count increase/decrease? (since it is only one of the variables responsible for increase in performance). Is there a way of isolating the other variables from the picture, possibly picking two processors of the same family, with the same architecture and clock speed, but different in transistor count? And then look at the amount of instructions each of them can handle. But what else would be a factor is the performance (cache memory difference, clock speed, something else?) Am I understanding everything correctly and can anyone give me examples of suitable processors or performance benchmarks?

Thanks.


texts: How to implement C language driver for SPI peripheral

texts:
I have been implementing device driver for the SPI peripheral of the MCU in C language. I would like to exploit interrupt mechanism for reception and also for transmission.
As far as the reception part I think that I can implement this via exposing the function SpiRegisterCallback into the SPI driver interface. This function enables the client register its function which will be invoked as soon as data byte is received (reception buffer full interrupt is invoked).
As far as the transmission part I would like to use some SpiTransmit function which will receive pointer to the data bytes to be transmitted and number of bytes to be transmitted. As far as implementation I am going to define some internal callback function of the SPI driver. This internall callback will be registered for transmission buffer empty interrupt. In this callback function the passed data bytes will be gradually placed into the transmission buffer. I am not sure whether this approach is appropriate. Can anybody give me an advice how to implement SPI peripheral driver which exploits interrupts for data transmission? Thanks in advance for any suggestions.


texts: Will this 18650 tp4056 parallel circuit work for charging and simultaneous power supply or will things break?

texts:
simulate this circuit – Schematic created using CircuitLab

Hey guys it's my first post here and i'm a bit unsure with this circuit, will it work or will there be some problems?

My suspicion is that the charging won't work correctly and there could be some under or over charging / balance issues but I'm not sure.

Also the current draw from the transformers will range from 500 mili amp to 4A depending on peripherals attached so on dead batteries im unsure if the transformers will get enough power as two tp4056's can only provide 2A, maybe a way of fixing it would be to add extra wires going from the tp4056 'in' pins to the 'in' pins of the transformers? (provided the micro usb 'in' supplies atleast 6A i would presume it could power the device while still charging the batteries?)

______________________________

YH11062B boost converter data sheet

Input voltage: 2.6-5.5V
Input Current: 0-3A
Output voltage: 5V
Output current: 0-2A
Short circuit protection: Yes

TP4056 DATASHEET: https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdf

Help would be much appreciated!

(EDIT: Datasheet + Circuit Diagram, hope this one is better //i'm new to circuit schematics)


texts: Why is this LC filter where it is, and what function does it perform?

texts:
My customer has a motor controller that apparently only works with an LC filter in front of it. This configuration trips out on undervoltage:

simulate this circuit – Schematic created using CircuitLab

This works fine:

simulate this circuit

(I'm leaving out details like a line impedance and precharge, but that's the general idea. I can add them back if anyone thinks they're relevant.)

I've never seen a motor controller require an LC filter like that. It is of interest to me that this filter has a pole at 49 Hz, and this equipment is designed to operate at both 50 and 60 Hz. Tests are being run at 60 Hz. If I've computed the frequency response right, that LC should have a gain magnitude of roughly 2x at 60 Hz.

Is this thing really just a tuned voltage doubler? What other function could this possibly perform?


texts: What is "rail pack" type of packing for electronic components?

texts:
I found triac from WeEn Semiconductors next type: BTA412Y-600B.
There is a link to official page of this component:

http://www.ween-semi.com/pip.aspx?p=BTA412Y-600B

For this product defined next type of packing:

  Horizontal, Rail Pack

I suppose that is tube form of packing. But am not sure.

Can anybody clarify it?


texts: At which amperage will 2 x 100A fuses mounted onto a dual fuse holder blow?

texts:
My question is related to a 300A rated dual fuse holder of the following type which is to attach to the positive terminal of an AGM battery:

If 2 x 100A fuses were to be mounted onto this fuse holder, would both fuses blow when the total load exceeds 100A or theoretically could 99A pass through each fuse (198A total load) without either fuse blowing?

Fuse specifications:

Fuse holder specifications:


texts:
I am using STM32F105RC for a project. I am currently using ST-Link to program the MCU, but i plan to upload the program using DFU mode.
For this purpose i am trying make F105 enter into DFU mode with no success.

I have connected the PA9 to HIGH.
Connected USART1_RX (PA10) and CAN2_RX (PB5) pins to low as mentioned in AN2606.
They have also mentioned to connect USART2_RX (PD6) to low as well.

But Since i am using a 64 pins package PD6 does not exists instead PA3 pin has option of USART2_RX which is also connected to low.
But still i am not able to make MCU enter into DFU mode.
Getting DFU to work is very crucial for my project, please help me to get this working.
Any help would be highly appreciated.
P.S. In normal mode MCU's USB is set to work as VCP which is working fine. Hence the USB connection is working just as it should be.


texts: Checking whether the system is linear or non linear

texts:
Consider this system equation where x(t) = input...
$$y(t)=x(t) \cos(3t)$$
Using the superposition theorem, we can prove that the system is linear.
For input x1(t), the output is
$$y_1(t)=x_1(t) \cos(3t)$$
For input x2(t),
the output is $$y_2(t)=x_2(t) \cos(3t)$$
For input [ x1(t) + x2(t) ],
the output is $$y(t)=[x_1(t)+x_2(t)] \cos(3t)$$
That is, $$y(t)=y_1(t)+y_2(t)$$
Hence the system is linear
But I can't get the meaning of this.
y(t) is linear with respect to x(t) means when we plot a graph of y(t) v/s x(t),I should get a straight line passing through origin.
But for the above case, its not straight line.
Please clarify this confusion....
Also ,if it is found to be linear, the system is linear for any x(t) or not?
I mean if we take x(t)=tu(t) or x(t)=t^2u(t)...now is the system  linear for both cases ??


texts: Does (stray) capacitance depend on voltage?

texts:
While thinking about how to reduce stray capacitance on my pcb, I got triggered by the question:

Should the stray capacitance depend on the voltage difference?

Acccording to the equation of capacitance(parallel plates:)

$$C = \dfrac{\varepsilon \cdot A}{d}$$

Where \$\varepsilon\$ is the dielectric constant , A the effective area and d the distance.

So based on this equation the (stray) capacitance is entirely independent of the voltage.

To me this seems counterintuitive.

If I have a  two traces on top of the ground plane (the two traces are far at a inifinite distance of each other, so lets discard trace to trace capacitance), where  trace 1 is at 1000V and trace 2 is at 10V.

My intuitions tells me that the parasitic/stray capacitance will be higher between trace 1 and ground compared to trace 2 and ground, basically because the electric
 field strength is higher.

Is my intuition right?


texts:
Hello Electronics Gurus and Experts.

I'm trying to build a sine wave inverter using PIC micro controller
However I'm not able to drive the power MOSFET.

After some research on internet i found that PIC controller can't drive a power MOSFET due to its low voltage.
So I decided to drive the MOSFET using a MOSFET Driver (TC4427).
The Sad part is still my MOSFETs are not switching ON and Off.
I connected the output from TC4427  to the gate for two MOSFETS IRF1404
but I can't see any output on the drain.
Any help on this will be much appreciated.

Please find the below output from TC4427. Probes are connected to PIN 5 and 7 of TC 4427 and Circuit diagram.

Datasheets:

TC4427.
IRF1404.

Yes it's alternating + and -.

Thanks.


texts: Recommended voltage/current for dry contact input?

texts: What would be a reasonable value for voltage and max current to used in conjunction with a remote dry contact output so that it can return to my MCU (through isolator)? I plan on using this input for both dry contact and open collector (in other words, I plan on having a pull up on my board). I don't want it too high so that a standard open collector output (30V/50mA-100mA) can work on it as well.


texts:
simulate this circuit – Schematic created using CircuitLab

A simple light bulb blinker circuit.......R4 is the bulb..I'm pretty sure I understand the functionality here. C1 initially starts to charge allowing Q1 to turn on. Once Q1 turns on the collector current of Q1 turns Q2 on hard and the base of R4 goes to approx 0v. This causes the right side of C1 to start to discharge through R2 and Q2.

My question is why does the voltage on the left side of C1 increase enough during the time the right side is discharging to turn off Q1. I see from simulations that this is what happens but I'm not sure why???


texts:
I am working on a PLC (Programmable Logic Controller) that receives input from four pressure sensors (4-20mA) and a proximity sensor. Two of the outputs actuate relays. The PLC communicates via Modbus protocol with an HMI (Human Machine Interface). The physical connection is done with an RS485 cable. I am not sure what is the current on the RS48 cable, I need to know how to calculate that. According with application notes from different manufacturers, the cable impedance is 120 ohms.
Also, I need to determine the power dissipated through heat. The PLC voltage supply is 24V, and  the nominal current is 0.5A. The manufacturer specifies a 12W power dissipation through heat, which doesn't sound quite right to me, because the PLC would have 0% efficiency, it would be just a heater...
Can anyone give me some suggestions?
Thank you.
Chris


texts:
I connected my esp8266 with USB to TTL CP2102 as follows:

USB to TTL      ESP
----------------------------------------------------
RX              TX
TX              RX(10K ohm resistor in between them)
GND             GND
3.3V            VCC, CH_PD,GPIO0,Reset

then I connected it with my laptop and opened arduino IDE. Why isn't responding to my AT command in serial monitor?


texts: In a USB cable, is it OK to swap the D+ and D- wires?

texts: I heard that D+ and D- are differential signals, does it matter if I swap them when connecting a USB device to the computer?


texts: In an SDRAM how do address rows/columns and rank width and bank width relate to the total memory size?

texts:
I have a Micron SDRAM (MT16KTF1G64HZ-8GB). The size of the memory is 8GB. I did some calucaltions and 8GB of data means 2^36 bits capacity. Now when I look in the Micron data sheet, the row address is 16 bits wide and the column address is 10 bits wide. That will give us a total of (2^16)*(2^10) bits which is 2^26 bits. But the memory width should be 2^36. How are the rest of the bits in the memory addressed?

The data sheet also mentions that this is a dual rank memory. Does this mean that there are two sets of 2^26 bits? Even then, that would result in 2*(2^26)=2^27 bits. We're still not at 2^36 bits.

The data sheet also mentions that there are 8 device banks. Does this mean that each bank has 2^27 bits? But even then it would give us 2^30 bit. Still not at 2^36.

I'm really confused. Could someone please help me?


texts:
Why the impulse response of this system:

\$y(n)=\sum_{|k|\leq3}^{}x(n-k)\$

is:

\$h(n)=\sum_{|k|\leq3}^{}\delta(n-k)\$

and the impulse response of this one:

\$y(n)=\sum_{k=0}^{+\infty}x(n-k)\$

is:

\$h(n)=u(n)\$ ?


texts: Modify verilog CORDIC code for -360 to 360 degrees

texts:
I am learning about CORDIC and implementing it in Verilog. I found this example which can calculate sin and cos for angles in the first quadrant (0-90).
https://github.com/freecores/verilog_cordic_core/blob/master/cordic.v

How would I modify this code to calculate sin and cos for -360 to 360 degrees. Would it be with if-else statements on the angle input? Where would that be placed for this code?

I understand I need to subtract or add  a multiple of 90degrees to get the angle into the first quadrant. Depending on which quadrant I rotated from I flip the value of sin & cos and/or change the sign of the result


texts: what is difference between servos & servo motors?

texts:
I am studying about basic of motors and i came across two terms

Is there any difference between two terms servos and servo motors? or they both exactly same??


texts: Analysis of overdamped series RLC circuit (from "Foundations of Analog and Digital Circuits")

texts:
I'm working my way through "Foundations of Analog and Digital Circuits (Agarwal)" and am, for the first time, stumped.

Specifically, they analyze an over-damped, undriven series RLC circuit in section 12.2.2. To illustrate the circuit's behavior when R grows very large, the limits of the roots s1 and s2 as R tends to infinity are computed.

Like so:

I'm fine with the result for s1. The one for s2 has me baffled and particularly so in light of the result for s1. For 12.70, I see the expression in parentheses evaluating to '1 - 1' when R grows very large (just as it evaluated to '1 + 1' in the case of 12.69).

What am I missing?


texts: Gain margin and Phase Margin Physical Meaning

texts:
I have been trying to understand the physical concept of Gain and Phase Margin.

What I understand about this is that a relative comparison around the critical point \$(-1,0)\$, which when converted to  magnitude and phase form turns out Magnitude = 1 and phase = -180°.

Also for a negative feedback system the Gain and Phase Margin should be positive, i.e., a system is unstable under the following 2 cases:

When the System/OLTF phase is -180° but System Magnitude \$>1\$. Thereby making Gain Margin negative.
I was able to correlate a physical meaning to this condition as the same would lead to a positive feedback condition with Gain \$>1\$ thereby leading to Unbounded output and hence instability.
When the System Magnitude = \$1\$ but System Phase \$>-\$ 180°. I'm not able to get a physical understanding of this unstablility case.

My questions:

How is after all phase used to comment about unstability of a closed loop system?
In this case after accounting for the negative feedback inherently present due to negative feedback the net phase might turn out to be positive, so how does that make the system unstable?


texts: Using an earthed function generator with an earthed oscilloscope and ground loops

texts:
I have a function generator and I noticed that its DC GND is internally wired to its earth pin.

Similarly I have an oscilloscope and I noticed that its DC GND is also internally wired to its earth pin.

So now If I use this function generator with this oscilloscope(with 3-prong power cords) wouldn't there be a ground loop?

If so, should I use 2-prong power cable for one of the instrument to eliminate it as a solution?

EDIT: An illustration for the question:

On the left side the box represents the function generator, on the right side the box represents the oscilloscope.

Circles represent the BNC connectors.

Number 1 and 3 are analog grounds of the function generator and the scope.

Number 2 is the GND shield of the coax cable, where the coax cable is connected from function generator to the scope (i.e. function generator and scope GND are connected)

Number 4 is the earth wire

L, N, E are the line, neutral and earth pin of the 3-prong power cable.


texts: Chassis ground on Ethernet RJ45 Connector

texts:
In the reference schematic of an Ethernet transceiver, I noticed that the chassis ground is connected to system GND by 1nF/2kV Capacktor(C24). What is the purpose of doing this?

The connector(J1B121ZCCD) contains transformer.

Because someone has pointed that my question is duplicate, I will explain. My question is that why the 2kV capacitor is there, and not why it is 2kV.


texts:
I am writing a MATLAB program in which I am doing OFDM symbol transmission through Fading channel:

Ncp=15;
Nfft=128 ; % size of fft
x = complex(randn(1,128), randn(1,128)); % the signal to be transmitted
IFFT_Data =ifft(x); % OFDM Modulation
Tx =  [IFFT_Data((128-Ncp+1):128), IFFT_Data];
h=rand(1,600); % the fading channel
y = conv(Tx,h); % transmission through channel
received_signal = fft(y); % OFDM demodualtion

From this point I want to reconstruct my transmitted data as you see when we use FFT. That means we are in frequency doamin, right? Then we need also to take FFT, now we are obliged to work in frequency domain. Can you tell me how I can reconstruct my transmitted data x?


texts:
I am trying to make a FM transmitter. For the oscillator part I picked a colpitts oscillator as it seemed relatively simple and I could get the pretty high frequency needed for FM with it. I built the Oscillator on a breadboard but unfortunately nothing I tried got it working. I was thinking would it be possible that the inductance of the wires was effecting it?
I simulated the circuit on "LT spice" and it worked. I also made a lower frequency version of it on my breadboard and it worked also, so I'm not too sure whats going on

This is an imagine of the circuit diagram that I drew up.
Thank you


texts: Choosing a breadboard: powered or externally powered?

texts:
Getting into electronics and want to select a good, large (roughly 9 x 7" or so) breadboard that I won't outgrow.

Trying to figure out exactly what to get, I see some $30-$40 externally-powered, larger breadboards that look interesting (ex. Allelectronics PB-3260), and then I also see some $80-$120 breadboards which feature a built-in power supply (ex. Sun Equipment PBB-4060B).

A college electronics lab I once visited had lab stations with what I thought were powered breadboards, and pretty large breadboards, at that. Those breadboards appeared to be best things to learn electronics, but they were probably expensive. I don't know if the $80-$120 ebay/amazon powered breadboards are comparable.

Is there any advantage/disadvantage the powered breadboards have compared to the externally-powered ones? My goal is to teach myself conventional circuit electronics as well as Arduino-type stuff.


texts: Unsure about RLC low pass transfer function

texts:
I'm unsure about the RLC low-pass filter transfer and frequency response functions I've been trying to calculate.

I need $$ H(s)=\frac{Y(s)}{X(s)} $$ where x(t) is Vin and y(t) is Vr. I calculated $$\frac{d^2v_c(t)}{dt^2}+\frac{1}{LC}v_c(t)=\frac{1}{LC}x(t)$$or$$ H(s)=\frac{1}{s^2LC+1} $$
This transfer/frequency response has been giving me the correct magnitudes but obviously doesn't give a phase angle. Have I calculated the transfer function correctly in this instance? Any assistance would be appreciated.


texts: Gain of filter is higher than calculated - why?

texts:
I have this circuit:

simulate this circuit – Schematic created using CircuitLab

The op-amp is being run off 15 and -15V supply rails, and I am using a signal generator to input a sine wave of different frequencies with an amplitude of 2V, then using an oscilloscope to record the output wave. I am using this data to calculate the gain of the filter at different frequencies.

For this project I am required to produce a table of predicted values for the gain of the filter. I produced this table and my maximum gain was about 1.5. In practice, I had a maximum gain of almost 2. My question is, why is the gain higher in practice than in theory? I thought that it could be other impedances in the wires, but I reasoned that that shouldn't affect the gain since the impedance of both the feedback loop and the input would increase equally.

I calculated the gain using the capacitive reactance formula as well as the formulae for resistances in parallel and in series. For example, the expected gain at 2100Hz:

\$R_f = \frac{(2 \pi * 150*10^{-12}*2100)^{-1} * 68000}{68000 + (2 \pi * 150*10^{-12}*2100)^{-1}}\$

\$R_{in} = 33000+((2 \pi * 21000 * 10*10^{-9})^{-1})\$

\$Gain = -\frac{R_f}{R_{in}} \approx -1.5\$

Why is my theoretical result significantly different from the practical result?


texts:
12V halogen lamps, do they need any special driving?

I have seen on some transformers that they output Half-wave rectification to the 12V halogen lamps. Is this how they should be driven or can they be used with DC or AC as well?


texts: What is input and output impedance of an opamp?

texts:
I have never understood input and output impedances of an op-amp. If anyone can explain what these two terms mean in an op-amp I'd highly appreciate it. Thank you!

http://www.eecs.tufts.edu/~dsculley/tutorial/opamps/opamps5.html


texts: Unexpected (unintended) capacitor charging explanation

texts:
Please first consider the below schematic. It is the balanced output part of an existing hifi preamp. Not my design, it's confidential so I can only reproduce the relevant part.

Things that might be of importance before I ask my question:

'IN' signal is the output from a discrete gain stage.
'MUTE' signal is -7V when inactive and positive when active
C2 and C3 are 16V bipolar types: ELNA RBD series

Measurements:

OUTP measures 0V with 0V input
OUTN measures -2.0V with 0V input
muting abruptly shorts OUTN (and causes strong audio pops) and C2 recharges within 1 sec to the same level as before.
There are 2 instances of the above schematic (obviously for L and R channels) and both charge to a different voltage (one to -2.0V, the other to -1.6V). This suggests it is related to capacitor leaking.
Opamp power supply is +/-15V, nicely symmetrical and locally decoupled.

Question:
Why does C2 charge to a small negative voltage level?
Next question might be how to solve it, but if I know why, I can probably solve it myself.
EDIT:
Most likely cause of this problem seems to be the muting transistor. According to specs they shouldn't cause any problems, but since they are directly at the output pins (with no added ESD protection), they could have been ESD damaged.
I've ordered some new ones and I should have them by the end of this year. It's a pain to disassemble and take out those transistors, so I might as well have replacements ready and do it only once.


texts: Why do some radio antennas require a path to ground and some do not?

texts: I'm currently learning the basics of radio and have noticed that some radios, such as crystal radios, have a monopole antenna that is essentially a wire buried in the ground. However, other radios, such as the portable one sitting on my desk, do not. Do antennas need to be grounded?


texts: How to correctly wire an interrupt pin, clock pin, PWM pin, SPI pin

texts:
I've a question about how to correctly wire some microcontrollers pins.

In particular:

Interrupt pin on microcontroller (pull up/pull down resistor and with which value)
Output clock pin from a microcontroller to an FPGA or another microcontroller (if are necessary capacitors or resistors)
PWM pins that drive LEDs or MOSFETS
SPI pins(MISO, MOSI, SCK, CS) they should have some kind of pull up or pulldown like I2C?


texts: Available Guidelines for Interrupt Driven Processing

texts:
Are there any available guidelines for the amount of code to have in a critical section of interrupt driven processing?

My personal rule of thumb is that the critical portion, (i.e. that between disable interrupts and enable interrupts), of any interrupt driven processing should be no more than about a dozen lines of code, (including those in any function/library/macro called), and that the processing should be as linear as possible.

I would expect something along the lines of:

disable_interrupts
if error_condition:
   set_error_flag
else:
   small_data_transfer
   set_ready_flag
enable_interrupts

However I have been asked to look into an existing project where some of the interrupts have  handlers where the call charts will not fit on a sheet of A1 (all in the critical section).

To clarify this is a "bare metal" project with no OS/Scheduler implemented - and all of the interrupt handlers start by disabling all interrupts - i.e. the original authors regarded every operation in every ISR as critical, (even the housekeeping is all inside of a disable/enable section).  There are a multitude of interrupts and hardware dependencies but as far as I can see some of the ISRs will be executing thousands of lines within the "critical" section.

I know that this is a problem and really needs to be completely rewritten but I can not find any standards, including MISRA, that I can point to rather than just saying "in my experience" - to convince the project management I need to point to some accepted standards.

So hence my question - Can anybody point me towards any standards or guidelines that I can use to back up my experience?  (Or of course am I totally wrong).


texts:
My 2.4GHz circuit is as follows:

(a)BLE (nRF51) -> (b)Balun -> (c)uFL -> (d)50OHM coax -> (e)matched-antenna

Does it even make sense to put a pi-match between b and c, so it can be tuned? My understanding is that I don't need to at all, and its best to go from b to c directly without a match.


texts: Why is the error in control system calculated against input?

texts:
In control system, the error is the difference between input and output. But why are we expecting to get the output same as the input. To get the exact input as output there is no necessary for the system since we have the output available i.e input.
I am not sure I have detailed it correctly but please respond if you get it.


texts: What gives the crystal oscillator a property of Inductor? How does energy transformation between electrical field and mechanical stress and strain makes oscillator work like a Inductor? I know how oscillator work but don't know how it can be modeled as RLC circuit?


texts: How to select resistor values for passive mixer

texts:
Total newbie question: I wanted to buy a passive audio mixer, and I wanted it to be cheap. I picked up one of these in a hurry, only to realise that it's a switch. But hey, it's cheap, so let's make it do what I want.
I figured out the routing in/out of the switch, de-soldered it, and dropped some resistors in place on the pathways. This way, the two L channels pass through their resistors then combine on the PCB, and the same on the two R channels. Those paths run to the potentiometer/volume knob; maximum resistance on the pot is about 42 kOhm.
For the resistors that I put in place, I'm following a couple of things I've read online, including this document which suggests 10 kOhm resistors. Another document suggested 4.7 kOhm. But I don't know how to select this value.
I've dropped in four 5.1kOhm resistors, and it does the job. But really, what should I be measuring (on the incoming line audio, or the destination amplifier) to determine what these resistor values should be? What are the risks if I go too low? What is the impact if I go too high? If I adjust the volume knob so that the resistance through the pot is > 5.1 kOhm, would that be bad?


texts:
I am fairly new to programming microcontrollers and I want to know if I can import libraries, that are written for Arduino, in other IDEs such as STM32CubeIDE.
For example can I use the library HX711, which is used to read data from load cell, in STM32CubeIDE?


texts: How to detect far field noise outside of a certified EMI lab?

texts:
For some background, we recently took a product to the EMI lab for EMI Pre-compliance testing and came close to passing, but we have some issues in the 30 to 100MHz range that just put us out of compliance. Unfortunately, as a small shop, we have been unable to see the same noise source in near field testing with our meters and probes, making it guesswork to try and resolve the issue.

We attempted to create a biconical antenna and it is picking up an amplified version of the noise that our probes see, but not the noise seen in the test lab. We have a 100MHz scope with FFT capability and a 1-3300 MHz spectrum analyser, but are still blind.

Is anyone able to offer suggestions on approaches that we might take or something we could build, in order to get that view of the noise that is eluding us?

The product has several cables which are the likely cause, but without some means to see the noise and then try to reduce it, we are stuck going to the test lab which is very pricey.

The following are the results of the test from the test lab. We are trying to get Class A certification but ensure some margin:

The test is the FCC 30MHz to 1GHz test for emissions.

The following is the spectrum analyzer output from our cobbled antenna at a distance of about 1-2 meters from the device, as shown in the subsequent image.

The device shown is a surrogate, as we don't wish to publish the product image just yet.

This next image is our oscilloscope and probe. The spectrum is pretty much the floor baseline at every point except above the power supply, where it is slightly raised but at a different frequency than what is seen in the official EMI lab.

We are using the following spectrum analyser, which worked well for us in reducing some spikes caused by the CPU and harmonics and helped get us to this point.

http://rfinstruments.com/SA0314.html

The antenna was roughly based on information from the following links without the machining involved:

http://everyspec.com/MIL-STD/MIL-STD-0300-0499/MIL-STD-461A_8679/

https://www.eevblog.com/forum/testgear/howto-calibrate-diy-emc-pre-compliance-antenna/

We could not find a plan for an antenna that was suited exactly for our frequency, so we hoped it might work despite the antenna factors not being a good match. We observed the WiFi quite clearly, but lack a good source in the 1-100MHz range to test against.

Thanks


texts: Unable to read back registers via SPI on the ENC28J60 Ethernet chip

texts:
I am using a CC1352P1 Launchpad from TI to connect with an ENC28J60 SPI-Ethernet bridge chip. I wanted to confirm first that I am able to get a response from the ENC28J60, so I tried to write to a register and read back the value I just wrote to that register. I am using a 4MHz SPI clock from the CC1352P1 master, with a polarity of 0 and a phase of 0.

For example, I wrote a value of 0b10101010 to the ERXSTL register at address 0x08 in the first bank. To do this, I wrote the value 0b 010 01000 10101010 or 0b01001000 10101010. I first sent in the byte with value 72 (or 0b01001000) and then sent in the byte with value 170 (0b10101010). I can see the SPI clock coming out of the CC1352P1, set at 4MHz, and I can see the Chip select from the CC1352P1 master go low during each byte transfer on my oscilloscope. I can also see the values that I am writing go out MSB first (namely, 0b01001000 and 0b10101010) on the MOSI line my oscilloscope. Then, when I try to read back this same register, I send the instruction 0b 000 01000 00000000 or 0b 00001000 00000000 or 0x08 as the first byte and 0x00 as the second byte. I am checking the MISO line on my oscilloscope, and I always see the last bit go high, every other bit is always low.

I tried also to read back the EREVID register by first setting the BSEL1 and BSEL0 bits to 11 to select the third bank, then reading from address 0x12 by sending in the following two bytes : 0b 000  10010 0000 0000 or first byte 0x12, second byte 0x00. I always get back 0x01, on the MISO line.

I tried setting the PHLCON register to get the LEDs to blink as well, by first writing the address of PHLCON (0x14) into the MIREGADR register, then writing the value 172 to write into MIWRL, then sending 59 into the higher 8 bits to write into MIWRH register. I did not get any response.

I am sure that the SPI communication on the CC1352P1 works since I have tested it with two CC1352P1 boards, one as a master and one as a slave, and I am also seeing the SPI clock generated and seeing the chip select go low when a byte is being transferred. Please help me out with what might be going wrong.

I am also not able to see any signal on the OSC1 or OSC2 pins on the chip, but I'm able to see a 6.25 MHz CLKOUT signal from the chip.


texts: Regarding Transient response of a Buck converter(Quantitative analysis...)

texts:
I want to know transient response of a Buck converter.
I have seen in so many occasions, like

when calculating Output capacitance,
datasheets consider, say in a transient event, loop will be effective after 3-4 cycles and up to that much time capacitor has to maintain the voltage and give the transient current.

When calculating compensation elements also,
transients were mentioned.

in some references, i found.,
inductor will decide the transient capability of Buck converter, di/dt = (Vin-Vout)/L.

Let's say, I have a transient demand from processor 6A/1uS.

I have Buck, Vin = 12V (10.8V to 13.2V), Vout = 0.9V, Ioutmax =15A, L = 0.47uH.

from above, (13-2-0.9)/0.47uH = 27.1A/us.. this looks like huge number...

in this case, how can i know the how much transient current can be given by buck.


texts: Is there a standard equivalent to automotive standard AEC-Q200 for the medical sector?

texts:
I want to ensure components of high integrity characteristics are utilised in a design by a third party.
In the automotive sector AEC-Q200 can be stipulated, e.g. (https://www.digikey.com/en/product-highlight/p/panasonic/automotive).  Is there any similar standard that can be stipulated for medical products?


texts: SG3525 Fixed output pulse (Without feed-back circuitry)

texts: im making CDI circuit in which capacitor charges upto 300v and then discharge through the IGBT connected . but when i ground the capacitor the output voltage ground as well which is obvious. to compensate the voltage drop across the output, SG3525 increase pulse width which further make the situation more critical, excessive load on the mosfet and transformer and could damage the input power supply  this is why i dont want to use feedback . i just need and adjustable duty cycle or fixed manually so i can reduce the power loss.(feedback circuit in the image is simple representation!!)


texts: Use "basic CAN" if "full CAN" is available?

texts:
From all I've read about both types my conclusion is that the only reason for using "Basic CAN" is to make message handling easier: I have to care about only one buffer.
One big drawback is that CPU load depends on CAN bus load (recently I overheard a discussion where exactly this was causing issues in a project).
So if I have "Full CAN" available, would there be any other justification for not using it?
To add some clarification:
Actually I'm not referring to any specific hardware. The project I mentioned uses a state-of-the-art microcontroller (Renesas RH850).
The Third Party CAN software package comes with a configuration tool, and in this tool it's possible to configure "Basic CAN" or "Full CAN".
"Basic CAN" means exactly what I wrote before: One Mailbox, no HW filter.


texts: Locked-Sync Sine Generator Covers Three Decades with Low Distortion

texts:
I am working on my first project in analog/board design, and although I know a decent amount of theory in electronics, I am lacking in practical experience.

I need an exact sine wave generator, and someone suggested looking at this:

https://www.maximintegrated.com/en/app-notes/index.mvp/id/4504

First of all, can I trust this design to operate as is?

This seems to be what I am looking for in terms of the output frequency range, but I have some questions about its operation
From its description, I think that the input is a square wave and the output is a sine wave that is 1/64 of the frequency of the square wave. Is that correct?
What is the point of the PLL+VCO (the first IC) of the design? Why not feed the square wave directly into the frequency divider?


texts: I wonder what is the difference between a Phasor, a Vector and a Space Vector? A phasor is also a rotating vector in space then it means that a space vector is same as a phasor? Also by definition a vector has magnitude and direction in 2D-space.. so then a vector and space vector both are the same things. Please correct me if I am wrong in this understanding.


texts: Powering up STM32L from Lithium Ion battery

texts:
I've just started with MCUs, so would like to at least to know whether I'm in the right direction...

Trying to power MCU STM32L100RC (just the MCU by itself) from a Panasonic Lithium Ion NCR18650B battery.

However, I'm trying to test it on the integrated circuit board first. See below.

1st part

The battery is constantly charging/discharging from PV solar array via DC-DC boost converter, mosfet driver, MCU and other components that make up - Maximum Power Point tracker.

I looked at the battery's data-sheet, and it seems that it can't ever output more than 5V, and over 200mA, battery's internal resistance is 29-39mohm.

So MCU is safe either way, since it said in MCU IC's documentation it can handle up to 1000mA.

Per documentation of the STM32L100RC MCU discovery board. It seems that my only option is to use 5V pin for power input, top right on the MCU.

MCU discovery board's manual also says that

LD1 (red) for 3.3 V power on

...

Does it mean MCU discovery board only requires exactly 3.3V?

What if power input varies? I actually tested with a DC power supply, and the MCU discovery board worked between 2.2V and 5V (I didn't risk higher voltages), but strangely enough I couldn't find the 2.2V minimum limit on the manual...

Btw, regarding that power input, it's just gonna be some voltage in, right? Like if I choose to do LDO regulator, output of LDO is just some voltage, correct? That voltage is gonna be connected through a wire to pin called "5V" on the top right of MCU discovery board?

Would this MCU discovery board still work if voltage in is below 3.3V? How about if it's above 3.3V? Say, like 6V? I guess it'd still work, but if it can work with 3.3V, then for efficiency it's better to stick with 3.3V, right?

2nd part

So I guess I will use an LDO regulator circuit to get power in for MCU discovery board.

I was gonna use a voltage divider circuit first for its simplicity, but it seems that the battery's voltage will vary between 2V and 5V(?), so it's better to use LDO circuit.

So, using LDO regulator. Do I just attach a wire at this point and then the other end of the wire connect to pin "5V" (top right) on MCU discovery board?

And in the LDO circuit schematic, the 5V voltage source - that's gonna be the positive terminal of a single NCR18650B battery, correct?

There are actually 27 of the 18650B cells in parallel, and 23 of those modules in series.

But I only need to use one of those batteries to power up MCU discovery board, don't I?

Last dumb question:

What does 1.65 V to 3.6 V power supply in datasheet mean? Does it mean the power into MCU or the output of MCU (what MCU can provide?) I think it's the latter.

I will stop with questions here for now.


texts: Precise definition of a "radial" electrical distribution system topology

texts:
I'm confused about what is meant by "radial" topology of an electrical distribution system. This site claims we can generally group electrical distribution systems into three classes: radial, loop, and network. A radial topology "has only one power source for a group of customers". Web pages here and here provide consistent definitions adding they are called "radial" because feeders radiate from a single source.

However, Santos gives a more general definition of radial:

  "There are two main topologies of structures for defining the layout of a distribution or transmission grid, the radial grid topology and the mesh grid topology. The radial grid is a tree shape topology where do not exist close loops. This means that you start on one bus and deliver power to the next without the possibility of finding the original bus, except if you turn backward."

This is not consistent with the first:

There is no requirement for a single source.
Power flows do not necessarily have to be unidirectional.
There is no mention explicitly of feeders. I.e. we could have a distributor line with multiple sources and sinks and still call it radial.

The question came up for me while reading some stuff on microgrids. Lasseter gives an example of a supposedly radial structured microgrid in the first figure below. So called feeders radiate from a point of coupling to the grid. But since this is a microgrid, each sub network has microsources and power flow controllers, and it is not strictly prohibited that power flow back up out of "C" and into "A" for example, when the microgrid is operating in islanded mode (disconnected from the mains). It is still a tree but not consistent with the first definition.

In the context of microgrids Guerrero et al. give another definition of radial. Discussing the line diagram in the second figure below they state:

  "... if every source is connected to at most two other sources, as shown in Fig. 1(a), then the microgrid is radial. Otherwise, it is meshed. If there is a line connecting Source 1 with Source k in Fig. 1(a), then it is a meshed microgrid. By far, the largest body of research work done in decentralized microgrid control has been for radial architectures of the type described in 7.

That looks more like a "loop" in the original author's terminology, but I guess if we consider the single line a distributor it is a tree like structure and consistent with Lasseter and Santos.

My take on all this is "radial", in the most general agreed upon sense, just means having a tree structure. It does not prohibit multiple sources and bidirectional flows. Specifically, multiple sources and sinks connected to a single distributor (as opposed to feeder from a single source to loads) would still be classified as a radial topology. Can anyone with experience in this domain back me up?


texts: Fall time for integrator with a large resistor

texts:
I know how to find the Outputvoltage when the circuit is "turned on" (Input x DCgain x (1-exp(-t/a)) , a=time constant , t=time )..but..

How to calculate  how fast the output voltage will go to zero when the circuit is suplied with e.g. 0 V DC.

Thanks in advance  :)


texts: Switching +12V, 0.5A output with a low +3.3V input?

texts:
I have MacMini with broken PWM  (pulse-width modulation) 4 wire FAN controller (FAN runs at full speed all the the time) and as MacMini schematic isn't available, I bought an external PWM FAN controller, but turns out that FAN socket +12V is constantly on, so I have idea to add simple switch, which get input from FAN socket PWM control signal + 3.3V and switch +12V, 0.5A output to the external FAN module.

Found this thread - Switching 12V with an active low 5V signal

So basically I need similar schematic, but with lower input voltage and with the contrary logic, so that the output voltage is +12V when the control signal is +3.3V, and 0V when the control signal is 0V.

Maybe adapt this one - NPN transistor to run 12V 0.5A from 3.3v 4mA

Does anybody have such schematic?


texts:
I am working on a project that requires that I transmit USB 2.0 over 0.1' headers due to an old design of a test board that used to use low speed USB.

The 0.1' headers are an unshielded and I worry that EMI will cause interference to other sections of the system. Is there anything else I can do to remove radiated noise other than wrapping the connection in foil? Is there a termination scheme or any other techniques to deal with unwanted effects/coupling from the exposed high-speed lines that would help?


texts: Very low wiper resistance Digital Pots - Anyone know of any?

texts:
I am trying to find a 1k linear digital pot which has a very low (preferably 0) wiper resistance. Any interface would be ok (apart from just up/down).

I found this article: http://electronicdesign.com/components/active-cancellation-pots-wiper- resistance
which could be a way around the issue.

What I am trying to do, is substitute the 1k pot in the classic fuzz circuit

http://www.geofex.com/article_folders/fuzzface/fftech.htm

with a digitally controlled one, and it needs to pretty much go down to 0 Ohm to get the full fuzz effect. I am not sure if the above 'trick' may interfere the fuzz's simple circuit which is extremely sensitive.

Does anyone have any suggestions, feedback or alternative idea?

Thanks!


texts: Equivalent circuits with one or multiple resistors

texts:
I am designing a circuit but I am facing a repetitive design that require too many resistors. The problem comes down to answering if the next two circuits are equivalent in terms of voltage drops:

simulate this circuit – Schematic created using CircuitLab

simulate this circuit

Note that there are actually n resistors: R2,R3,...Rn. All values are known and can be different from each other(R2<>R3<>R4<>...<>Rn) and R1,R2,..Rn have the same values in both scenarios (the values on the drawing are incorrect).
The question is as it folows: Is the voltage drop on R2,R3,...,Rn same in both scenarios?


texts: Can I use a relay to control light switches?

texts:
I'm working on a project where I use a Raspberry Pi to build smart home devices. One of the devices I want to control is my room's light switch. I've done a bit of research and found out that my light is single pole switch with an identifiable positive and negative lead. My plan is to get rid of the switch and replace it with a relay.
My problems:

The relay isn't able to hold two states unless I tell it to close the circuit continuously (which I heard isn't good for the contact pads inside the relay.)
Can my relay handle the voltage coming through a light switch?

My relay is a JQC3F-5VDC-C


texts: Modifying power strip in enclosure to attach to power entry connector

texts: We are using an off-the-shelf power strip to distribute power to several devices in a large aluminum, painted Hammond brand enclosure.  We'd like to be able to switch the power on and off with an externally accessible switch, so we had the idea to cut the plug off the power strip, strip the cables, crimp on quick connects, and attach it to a power entry connector (specifically a Schurter DC12.5102.003, Digikey part 486-2251-ND) attached to the back panel of the enclosure.  We'd like to know if this is a safe way of doing this, and if so, do we need to attach the ground to the enclosure (after clearing a connection point of paint)?  Any suggestions for alternate ways of doing this would be very welcome as well.  Thanks!


texts: What should be switching voltage rating of relay in a 380VAC 3 phase system?

texts:
I am hooking up a system where there is 2 sources of power available. One source is the grid power, and the other is a generator. The grid provides me with 3-phase 380VAC with a neutral wire; and on the other hand, the generator provides me with 3-phase 380VAC BUT no neutral wire. I am using a SPDT relay on each phase, and all relays are controlled through a common signal coming from a micro-controller. So, all three relays are switched at the same time. The load is a battery charger that has a 3-phase input and does not accept a neutral wire, just three hot wires.

simulate this circuit – Schematic created using CircuitLab

Now, my main question is when I am looking for a relay suited for my need, should I look for relays that have a switching voltage rating of 220VAC or 380VAC?

The confusing part for me is that if I measure voltage between one phase and neutral the voltage is 220VAC, but 380VAC line to line. So, I am not sure whether I need a relay with a switching voltage rating of 220VAC or 380VAC!

Thanks


texts: Why are deep cycle batteries rated in amp hours instead of watts hours?

texts: Why are deep cycle batteries rated in amp-hours instead of watt-hours? For example if I see a 85Ah battery, I multiply 85Ah x 12V to get 1020 watts. As household electricity use is measured in watt hours (hence a kill-a-watt) this information seems more useful. What is the important thing that I am missing with the amp labeling?


texts: Is it bad for an RF amplifier to leave it on with no input?

texts:
I work in a physics lab where we have some inaccessible experiments. One of them involves an RF power amplifier (a ZHL-32A+ from Minicircuits) driving a 50Ohm load that we can't access, but we can control its signal.

Sometime we have to leave this for long periods (~months) not in use. When we're doing this, is it better for the amplifier's aging to leave it with no input RF or with the normal signal? We don't have the option to turn its power off fully.


texts: Four layer board in Altium Designer, the power and ground layer is shown without copper pour

texts:
I have made a four layer board using Altium Designer, while viewing the gerber files in the gerber viewer (Gerbv viewing software) for the power plane and the ground plane, I am unable to see the copper pour I am only able to see the slots for through-hole via and micro vias. After that I called Altium re-seller and he told me that it is the native format, if you are not seeing the copper it means there is copper in it. I have attached images below, but I am unable to get the why there are no copper pour in the power and ground plane, if I give it for PCB manufacturing will the copper pour be there in the Ground and Power plane.

Top Layer

Power Plane

Ground Plane

Bottom Layer


texts:
simulate this circuit – Schematic created using CircuitLab

In the circuit the current i1 is flowing from external device. Now my doubt is what is the voltage developed at the analog input of the micro? I am asking this question since i don't know the resistance of the analog input. Can i simply neglect the resistance of the micro analog input, or i need to refer from the data sheet. Can i also neglect the 56K resistor in series? In that case is the voltage at the analog input is Is*4.7K? Please help


texts: Most affordable FPGA dev kit for learning VHDL and FPGA theory?

texts: I'm looking for something that I can play around with but not spend too much on. I'm not eligible for an academic discount so take that into account when making suggestions.


texts: I want to dim a lamp around 70W or more using arduino. I have found two ways for doing that. The first one is to make a circuit that "cuts" the sine wave and produce the dimming effect (link). The other way is to make a circuit that uses a PWM pin to dim a lamp (link). So what is the best solution and why? In my opinion the one with the PWM pin is better because it uses only 2 cables to send signal to the circuit and it is much easier in coding.


texts: Need help with RTL (Register Transfer Level) circuit implementation - Euclidian GCD algorithm

texts:
I'm looking for help regarding the following algorithm and implementing the logic circuit. Here it is in pseudocode:

if b = 0
    swap values of a and b.  b has the GCD. done.
if a = 0
    b has the GCD. done.
if a < b
    swap values of a and b.

Loop: a = a - b
    if a >= b
        go back to Loop.
    if a > 0
        swap values of a and b
        go back to Loop

b has the GCD. done.

I've written some RTL code and it doesn't seem to be an issue; the real issue is my circuit design!

I suppose one would use a shift-subtract division implementation? I suppose I really just need help deciding what registers and arithmetic chips I'd use. Going to use Logisim.


texts: Can I take the voltage across diode to be same as the input voltage in a limiting circuit?

texts:
My doubt is a trivial one, can I take VD1 and VD2 to be V1? If so doing that doesn't make sense to me 'cause when the current flows VD1 is certainly not equal to V1.

This isn't a Homework question, I found a similar question in my textbook with D2 reversed (Given above) and there I can understand why VD1 equals V1, as for the off condition no current flows through the 10K resistance but here this isn't the case. If I'm right then the following solution is wrong, how should I proceed then?

Any help is highly appreciated.


texts: How do I "cap" a wire so it doesn't short or electrocute someone?

texts:
I'm repurposing a PSU that I recently replaced. I'm using it in a project that needs high current supplied. I don't need all the wires (as you could imagine), but I don't know how to seal them off safely.

I was thinking about trimming them shorter and then adding a bit of electrical tape over the end and doing a little bit of shrink wrap to hold that in place. Is this a good idea? I generally like to stay away from electrical tape, but I can't see any alternatives, and the shrink tubing would hold it in place. Ideally, I would desolder the wires from the PSU, but I'd rather not mess around with it and all the warnings about capacitors. How should I do this?


texts: Programming a 3.3V Atmega chip using USB

texts: I am planning to use Atxmega128A1U in a battery monitoring system. This chip comes with USB device support. However, it is a 3.3V logic chip with input voltage limit of 3.6V and I want to use the USB port on my laptop to program the chip. How to interface the 5V USB port to 3.3V atmega chip? Shall I use a logic-level converter or is there any other better solution? I want the system to be self-sufficient, so I don't want to use an external programmer, once the Arduino bootloader is burned.


texts:
I understand that with synchronous FPGA, the whole execution is done in cycles. What happens when my circuit has two parts which give outputs in different cycles (one has greater depth than the other) and I need the outputs in a different part of the circuits in a single cycle? Is there any better way than just adding logic gates which do nothing in order to get delay of the required number of clock cycles?

I know that I usually don't have to care about this when programming FPGA's, but I would like to understand it.


texts: Power consumption of Cortex-M7-based microcontrollers

texts:
I'm designing a USB-powered microcontroller board, and I'm considering choosing a Cortex-M7-based microcontroller for it (I want a double-precision FPU, along with other features M7 offers). Currently, there are 2 MCU families commercially available:

STMicroelectronics STM32F7,
Atmel SAM S70 / E70 / V70.

Because my board will only be powered by USB cable (through Type-C connector / USB 3.1 PD chip), I thought of choosing a MCU based on their power consumption - but I couldn't find any numbers.

STM manufactures it's MCUs using pretty aged 90 nm process; Atmel doesn't disclose any manufacturing details, but collective consciousness of the Internet says it's 55 nm process - thus it should be more power-efficient.

Are there any figures/estimates publicly available on the power consumption of the above MCUs? Any measurements of yours?

I totally understand that there are different usage scenarios possible; also, each MCU comes in a variety of variants among which power drain may vary. I'm not looking for comparisons, but rather for various measurements or different chips, which will help me estimate.

Thank you in advance.


texts:
The schematic is part of a circuit for a radar project by MIT. The shown schematic is a gain stage followed by what appears to be two Sallen Key LPF stages with cut-off frequency of 15 KHz. There is a +5V DC bias probably to avoid clipping the signal. The MAX414 Op-Amps are powered with 0, +12V.

I would like to change the cut-off frequency to say 100 KHz by changing the values of the Rs and Cs. The gain should stay the same.

I know how to design one active LPF stage as in here. However, what I can't understand is how to match each of the stages in the MIT's circuit to the standard circuit of Sallen Key shown in the link. More specifically, what is the MIT's value of R1 for each stage?

What is confusing me is the existence of an extra resistor in each stage: Take the second Op-Amp for example which is the first LPF stage, should we consider R1 to be 8.45K or 102K? or the parallel equivalent? If we want to strictly follow the standard Sallen Key topology, the 102K shouldn't be there. What is the purpose of having it? and how is it going to affect the cut off frequency that depends on R1,R2,C1 and C2?


texts:
I had a general question about logging accelerometer data on the Arduino or any microcontroller.

I had a KXPS5-3157 accelerometer hooked up analog mode to measure z-axis vertical acceleration in a car going over bumps.

My question is that would I have to have an accurate time reference like a real time clock or some piece of code that kept accurate time to plot acceleration G force? Since acceleration is based on time.

I want to get the vertical acceleration of potholes, but to make the data meaningful I want to plot it, but acceleration is based on time, so is it possible to have the Arduino log it with time? Or it doesn't matter?


texts:
Two capacitors are parallel connected with an open switch. Both have a different capacity in which: $$c_1>c_2$$
and both charged with a different voltage
$$v_1\neq v_2$$
and now we close the switch.

What will the voltage be on the capacitors and will it hold Tellegen's theorem?

I believe it won't, but I couldn't write a proper proof or to find the common voltage.


texts: How do I drive a MOSFET working under high voltage while keeping it insulated from the rest of the circuit?

texts:
I want to drive a MOSFET with a 50Hz, 50% duty cycle clock pulse. The voltage to be switched is as high as 300V DC. The section inside the dashed lines will stay electrically isolated from the rest of the circuit. I am planning to use an optocoupler for isolation (I'm open for any other suggestion).

Best solution I can find is using a voltage divider network (as seen in the second schematics) and control it with the optocoupler. But I don't think that this is an optimal solution, because there are two major problems.

I have to use a bulky power resistor for R1.
Switching losses. Gate capacitance of a typical MOSFET is about 5nF. Time constant for a 5nF capacitor charging over a 20k\$\Omega\$ resistor is 100\$\mu\$s which is 0.5% of the switching period. The maximum current through RL will be 10A, and the Rds,on resistance of the MOSFET will be 50m\$\Omega\$ at most. So the switching loss will approximately be
\$(10A)^2 \times 50m\Omega \times 0.5\% = 25mW\$.

I can increase the values of R1 and R2, but this time the switching loss will increase. There is a trade off. Either way there will be a heat source in the circuit, and some energy will be lost.

What is the efficient way of driving a MOSFET like this?

EDIT: What about this circuit?

With enough dead-time between on states of the two optocouplers, the required rated power of the R1 resistor may stay below 1W. Do you see any problem in this new circuit model?

EDIT2: I decided to put external darlington transistors for supplying more current to the MOSFET gate.

The gate voltage will drop down to 1.4V at low state, at which most MOSFETs are completely turned off. Is this new circuit feasible?


texts: Modelling a phase shift signal that is delayed

texts:
The exor gate measures the phase shift between two clock signals.

Let's say the phase shift is (phi) 0. I can write (phi) 0= (omega)w*t.

Now if I were to add a delay block after the exor, I would get (omega)w * (t+td) where td is the delay. So, (omega)w*(t+td)= (omega)wt + (omega)wtd= (phi)0 + (phi-d)0d

Is this correct? Adding a delay adds a small phase shift to the existing phase shift?


texts: Using a Mosfet Gate driver to directly drive a small stepper motor?

texts:
I need to control some small, low current stepper motors from a 3V ARM micro controller.

The motors typically require 5-12V at 400mA (30 ohm 41mH windings).

What occurred to me is to use a Mosfet driver chip to directly drive such a stepper.

The type of devices I am looking at are

Microchip TC4420/29 - 20V 6A low side.
IR2110  20V 2A  - high and low side.

simulate this circuit – Schematic created using CircuitLab

I saw an appnote from IR stating that the HI/LO driver can be used as a dual low side driver in an automotive application. This would be ideal since one device would potentially suffice for a full H-bridge.

The electrical specifications look OK. But nowhere in the specs of either is there any mention of driving inductive loads.

The MCU pins would normally be fed by PWM, current control is not usually applied because the winding resistance limits current sufficiently. The PWM provides 'analog' drive for reducing vibration and noise. I guess it could be used for micro stepping as well.

A small resistor in the ground return can be added and suitably connected to an ADC if current measurement and control are required.

The obvious requirement would be to provide freewheeling diodes to clamp back EMF and a capacitor to absorb the energy.

I wired this up on a breadboard and manually switched the inputs. All works OK, but the driver chips get pretty warm in seconds. This could be due to the noisiness of the switching (bare wire against pin).

I've also read about Mr. Miller's findings which may be responsible for the heat.

The current and voltage profiles differ between inductive and capacitive loads as commented by @madhatter this may limit the amount of steady state current that can be supplied well below the maximum rating.

(Despite a low) RDSon of 2.5 to 7.5 Ohms will cause heat dissipation problems with these IC, hence underrating current 10*. If the device can run 12V 6A spikes into mosfets at 1MHz they must be able to get rid of a lot of heat.

Slower switching speeds (10-50KHz), keeping period of current supply short and reprofiling current draw with a small cap mitigate some of these problems.

An exercise for testing will be to monitor the heat output in practical circuits.

The mechanics can hold position in many cases, so steady state current requirements can be managed in some cases.

Saving on complexity, components and board space would be a great bonus if this or a simpler circuit can be made to work.

I am sure that something like NTMD6P02 integrated to TC4427 would find a lot of application.

Before smoking the drivers or adding drive mosfets(e.g. NTMD6P02), has anyone experience doing this sort of thing?

Does anyone have a simpler, neater and cheaper way of doing this?


texts:
I'm working on an RGB LED project. I'm using this as the power supply: https://www.sparkfun.com/products/114
It uses an LM317 which according to the data sheet can supply up to 1.5A. The LED's I'm using are these: http://www.adafruit.com/products/314

And the mains power supply I'm using is a 12v DC 2 AMP one.

Here's the problem. If I have just all of the red parts of the LED's lit up (I have 8 LED's), within about a minute the voltage regulator is far too hot to touch and I disconnected it when it started to smell funny. I attached a coin to the heatsink part of the voltage regulator (Not great I know, but I'm still waiting for some proper heat sinks I ordered to arrive) and within about a minute that too was far too hot to touch.

How can this be? Each red part of the LED uses 20mA, so multiplied by 8 that is 160mA. So the circuit isn't drawing too much current, is it? I'm using 150 Ohm resistors for each LED.

Why is it heating up so much, and what am I doing wrong?

Thanks

(Also, if I powered up all red, green, and blue parts of all 8 LED's, the voltage regulator gets blisteringly hot)

(I've just being reading about "switching" regulators being used as they produce less heat, would this be a better idea?)


texts: Identify MOSFET and find equivalent - top marking "P40 1340" or "S36 1410"

texts:
Please, help identify this MOSFET and equivalent.  One circuit has them marked as "P40 1340"  and the other has "S36  1410".
It's part of a circuit of 2 MOSFETs that act as power switches controlled by an MCU pin.  It operates down to 2 Volts and handles up to 3A.
I am hoping to find the same or with equivalent rating. I found a MOSFET numbered as "TC1410", but it does not seem to have the same package even offered. And I could not find any MOSFETs with a marking of "1340".
EDIT:  If cannot identify them, I think this could be a substitute:
IRF7317TRPBF, Infineon Technologies,  MOSFET N/P-CH 20V 8-SOIC
https://www.infineon.com/dgdl/irf7317pbf.pdf?fileId=5546d462533600a4015355f5b8de1b3d
DMC2038LVTQ-7, Mosfet Array N and P-Channel Complementary 20V 3.7A
https://www.diodes.com/assets/Datasheets/products_inactive_data/DMC2038LVT.pdf


texts: Why do graphics card power cables (PCIe, etc) use more than two wires?

texts:
High-end graphics cards need more power than can be delivered through the PCI slot.  One option would have been to deliver the extra power using a 4-pin Molex or SATA power connector, but recent graphics cards need even more power than these can deliver.

The computer industry has introduced a series of "PCIe power connectors", each having two rows of pins: one for +12V and one for ground.  The later connectors add more pins (4->6->8) and more wires to carry more current.

  Question: why did the industry decide to add more pins instead of using thicker wires?  In particular, is there an electrical safety/reliability reason for using a larger number of low-current conductors instead of a smaller number of high-current conductors?

Adding twice as many pins bumps the connector and cable price up much more than using pins and wires that are rated for twice the current (up to a point of course, but PCIe is nowhere near the point of diminishing returns).  In theory you can use a pair of 4-pin wires in place of a single 8-pin wire, but in practice this doesn't really happen all that often and I doubt it was the deciding factor.

I can certainly see how manufacturers want to make sure users don't use a low-current cable on a high-current connectors, so if they had stuck with 2-conductor wiring I'm sure they wouldn't have left the connector unchanged.  Most likely they would have adjusted the keying on the socket (that's one great thing about those Molex mini-fit connectors, they've got an exponentially large space of keying choices to stop people from doing stupid things).


texts:
The gain and bandwidth product of an ideal op amp is always constant. This statement seems to be true in the '-20dB slope' region. But this doesn't seem to be true for the low frequency region.
The two shaded regions below doesn't seem to represent the same gain bandwidth product.

I am not confused here with plot for gain at a particular bandwidth, which may seem as below and does not satisfy the gain bandwidth product (it should not) in the constant gain region.

What I think (I know I am wrong) why isn't the gain bandwidth product made something like this:

Can anyone please explain where am I wrong in my reasoning?


texts: How to plug CAN Bus radar to Pixhawk Cube Orange flight controller?

texts:
I want to plug my radar (which is a CAN Bus) to my Pixhawk flight controller. (https://ardupilot.org/copter/docs/common-thecubeorange-overview.html)I bought the radar from China and the site i bought it from went down. I dont have any manuals in my hand. I've managed to configure most of the parameters in Mission Planner but i need to know the address of my radar. (which have to be 0- 127 in Mission Planner i guess) and bitrate. How can i do this?
Edit: I found an USB to CAN Analyzer here https://www.seeedstudio.com/USB-CAN-Analyzer-p-2888.html can i use this to find address of my radars?


texts:
Do internal signals ever add any delays?
Are they not equivalent to d-flip flops which require time to propagate?
Consider if i had an entity with 1 input port and 1 output port
I instantiate a component inside the entity
On the rising_edge of the clk, the inputs to the entity are clocked
The input port is connected to the component input port through an internal signal
The output port of the entity is also connected to the output port of the component through an internal signal
Would i see the outputs of the entity at the same rising edge of clocking the initial inputs?
The reasons im asking is because i have tried it and sometimes there is delays sometimes there are not delays
What about when an internal signals connects 2 components together in an entity?
Thanks


texts: Is it possible to access Emulating Data EEPROM of PIC32 using another PIC microcontroller?

texts: I tried to use Flash memory of PIC32MX as eeprom (some address) to store data using microchip library , Is it possible to access created eeprom using another PIC32 microcontroller(i2c) or ARM ?


texts:
First Question:
I bought a few rolls of high density 5M individually adjustable LED strips - 14.4 Watts/M @ 24V which equals to 0.6A per meter.

I was advised I could run up to 10M in series which is 6A in total. But the LED strip came with a 22AWG (max 1A) wires for power transmission. Even running 5M would be 3A which is still well over 1A.

It's a short run yes but isn't it still a fire risk? Searched around but it seems everyone is generally OK with the thin wire that comes with LED strips.

So what am I missing here?

Second Question:
Does it matter if a LED controller connects data line in the middle of LED strip instead of the start/end of the LED strip? Reason being it's a staircase 21-steps LED strip run so sometimes the light effect should start from the bottom to the top when going up and vice versa from the top to the bottom when going down.


texts: I decided to create this circuit and solve it with mesh analysis. Then, I thought I could find the Thevenin Equivalent, but I have no idea where to start! I can't get to understand how to get the thevenin voltage when I have the open circuit right in the middle. If you could help me out with the way I should do it, that would be great. Thanks! (I'm trying to solve it myself, so I'm looking more for an explanation than an answer itself)


texts: Writing data over Serial comm //Arduino & MPU6050 gyro+accelerometer

texts:
I'm new to serial communication and I am just scratching the surface, therefore please bare with me.

What I need to accomplish is the transfer of the gyroscope data I gather on my Arduino to Processing on my Macbook. I already have the code ready that reads my gyro/accel data, applies a complementary filter and outputs this to the serial monitor as a string.

I'd like to learn how to send this data directly from the Arduino to Processing.

What would be the most effective way of sending data that can be positive and negative over serial?
I've searched around and came across using strings over serial and read/split them in Processing. I'm not a fan of this method. HighByte& lowByte and float/char byte array seems as an alternative but gets too complicated for my current knowledge and understanding.

It would be great if someone could push me in the right direction or just help me altogether with learning serial communication and sending/reading data from a Arduino to Macbook/Processing app. I know in theory whats going on inside but code-wise i'm kinda lost.

Thanks in advance,


texts:
I'm trying to make a very simple circuit to switch an led using a transistor. My supply voltage is 16v, my control signal is 3.3v from an esp8266 GPIO, and my transistor is a 2222a NPN.
My led has a Vf of 3-3.2v and If of 20 mA. So I've worked out the led resistor value to be
(16 - 3) / 0.02 = 650 ohms
I then worked out the base resistor for the transistor to be
Ib = 5(0.02 / 100) = 0.001
Rb = (3.3 - 0.7) / 0.001 = 2600 ohms
I've tried base resistors from 500 ohms all the way to 13k and none get my led to full brightness. I am now very confused. This seems so simple.
Now when I go to hook it all up and measure the voltage across the led with my multimeter, it is 1.9 V, visibly dimmer that it should be. I know my led is OK because I measured the voltage of that same bulb with a direct connection, no transistor, and the voltage was 3.1 V and bright.
Here is my circuit diagram:


texts: How exactly does a basic EMF sensor work?

texts:
Halloween is coming up, and inspired by the simplicity of this project, I'm asking for a more technical explanation (and / or resources to do that) - this seems to be either missing or too obvious to explain.
The premise is simple: come up with a device to measure 'electromagnetic waves', e.g. in wifi spectrum, 2.4GHz or something emitting from a powerline, here, ca 200-220V at 60Hz (unsure what frequency that would equate to). Somehow, here, this is achieved by only a resistor and an open circuit.
I know Ohm's law U=R*I and, from what I read, the sensitivity increases (at least monotonically increasingly) with the resistor value (e.g. 10k less sensitive than 1mOhm).
Questions:

How exactly does this measure EMF, and is it possible to measure multiple frequencies, by simply attaching multiple loose wires (and does the thickness matter?)
What is the role of the resistor and how does it help to measure the signals properly? Can we explain the sensitivity of this sensor by Ohm's law, i.e. a linear relationship?

// code used on the cited project, all credit goes to the author Patel Darshil
int inPin = 5;             // analog 5
int val = 0;                 // where to store info from analog 5
int pin11 = 11;         // output of red led

void setup() {

  Serial.begin(9600);

}

void loop() {

  val = analogRead(inPin);                    // reads in the values from analog 5 and
                                                                   //assigns them to val
  if(val >= 1){

    val = constrain(val, 1, 100);               // mess with these values
    val = map(val, 1, 100, 1, 255);        // to change the response distance of the device
    analogWrite(pin11, val);                    // *note also messing with the resistor should change
                                                                   // the sensitivity
   }else{                                                     // analogWrite(pin11, val); just tuns on the led with
                                                                  // the intensity of the variable val
    analogWrite(pin11, 0);                     // the else statement is just telling the microcontroller
                                                                 // to turn off the light if there is no EMF detected
  }

 Serial.println(val);                                // use output to aid in calibrating

}


texts:
I am controlling two stepper motors in from a Genie Microcontroller and driving them by a ULN2803A. I want to know what is the shortest time i can change the phase. Is it dependent on the ULN2803A?
Thanks in Advance,
Dean


texts:
I've had electromagnetism classes back in uni, but I'm having a hard time linking them with that matter:

Take a car antenna -which I assume is simply a wire, coiled or not-, and apply a voltage across it. The way I see it the current will only be limited by the resistance of the wire, which also means all the power is lost via Joule dissipation. Yet, electromagnetic waves are emitted, which represents radiated power (it has to be nonzero as we can capture it on the receiver end). So how can we account for that power in the power budget?
The underlying problem that made me realise this is: how can I calculate a rough estimate of the radiated power, or at least a maximum value, of the radiated power if I know how much electric power I put in? This is to make sure it won't disturb cellphones even though I'm pretty sure it won't - stepper square pulses, 28V 50W switched @ ~10kHz [rise time 500us], cables in single turn loop of ~15cm in diameter.


texts: Is there any benefit to using a voltage booster (such as Batteriser) on "dead" batteries?

texts:
The Batteriser [Edit: removed dead, harmful link] is a crowd-funded product intended to extend battery life by boosting the voltage. It is basically a joule thief that is in a tiny package that slips over the cell.

Dave Jones of EEVBlog did a video debunking the product:

EEVBlog #751 - "How to Debunk a Product (The Batteriser)"

Which the Batteriser people responded to with a video of their own:

Batteriser Batteroo: "Conclusion - Comparing batteries with power supply box"

And a response from Dave:

EEVBlog #779 - "Batteriser: How to Measure Battery Cutoff Voltage"

The latter two videos primarily deal with the Batteriser promo team's failure to understand how to measure voltage provided by batteries under load versus out of circuit. They believe that a power supply is an "unfair" test because it behaves different from batteries, or that skeptics failed to consider battery internal resistance, etc.

While I think it's obvious that the Batteriser people have failed to grasp some basic concepts, I do question whether a joule thief type circuit is a good way to utilize remaining energy in a cell. (Certainly not the 80% that Batteriser claims we throw away.)

Is there any benefit to using a voltage booster on batteries that are below a device's cutoff/operating voltage?


texts: Different weights on different temperatures - load cells and ad620

texts:
I have a set of load cells connected to a AD620. Everything is working good except when I change the temperature. The temperature can vary between -10 and 50.
I have the AD620 connected to an MCP3208, the MCP is connected to Pi via SPI.

For instance, when the exterior temperature is around 20 degrees the calculated weight is correct. But when the exterior temperature is 5 degrees, the weight is 5 kg less than the expected.

How can I control this ? Ideas ?

Thanks.

(More explanations added)