texts:
Recently I was following an online project guide, and ordered many components online.

One of the components, a 0.10uF capacitor with 50V rating, returned some results which said they were "MIL" rated.

The stats appeared the same between the "MIL-Spec" and regular capacitors, same heat rating, etc. The MIL-Spec capacitors seemed to contain lead, but that was the only discernible difference, other than shape (square instead of rounded). They weren't really any more expensive when buying only a few.

At the time I placed my order, the MIL-Spec caps were all that was in stock for my project, so I ordered them. They came with a certificate that they were MIL rated, from the original manufacturer, including military identification numbers, etc.

Example:

MIL-Spec: https://www.digikey.com/product-detail/en/kemet-mil/CK05BX104K/1001-2004-MIL/2397486

Standard: http://www.digikey.com/product-detail/en/vishay-bc-components/K104K10X7RF53L2/K104K10X7RF53L2-ND/2820500

What is the real difference between MIL-Spec components and regular components?


texts:
A similar question has been asked, but I wanted to get to a more fundamental understanding of when, in general, power supply pumping occurs in a class D amplifier.

  In general terms "power supply pumping" is the return of energy from a load to a power supply via output switches so that the power supply is forced to accept energy via an unintended path.

This quote was from an answer that was given before. How is the energy being supplied back? Is it mainly due to the inductive voltage spikes from the abrupt current switches? If I was driving something that was not a speaker, and say, purely resistive, would this still happen, or is it irrespective of the load type?

I was told that using a full bridge output (4 driving FETs) would help alleviate this problem versus using just a half bridge topology, but I do not see how. Any links to outside reading would be useful.

EDIT: I don’t have a specific schematic issue, I just wanted to know more about this specific issue that occurs.


texts:
What is the technical term for these tones (often multi-frequency) which I uploaded here that radio devices used by Police, EMT, etc produce before or/and after a voice message and why they differ in pitch, frequency and other sound characteristics? Who did first developed the idea of them? Are these sounds registered for each manufacturer?

Someone referred to them as Squelch, which I'm not sure, because I couldn't find any sound sample for them online.

Also note that I'm not referring to any noise here. I'm looking for a term to address those certain tones that radio devices make on their own, like a musical instrument!

Please note that the sound file I posted is a mix of 2 different sound files from different sources.

I noticed that vintage Eurosignal system was used to produce sounds/tones similar to those that two-way radios make, a series of tones which vary in frequencies.


texts: Transistor resistance for switching analog signals

texts:
I would like to use two transistor to switch on/off two paths to an ADC input so that only one path is active at a time. Is this a bad practice? I'm aware of analog switches but don't know if something that complex is necessary for my simple application. Is there any information about the resistance between the collector and emitter of NPN transistors? I want to make sure using the transistor as a switch for the analog signal doesn't mess up my analog readings in the ADC. Accuracy and resolution is important here (true 16-bit ADC). Would a particular type of transistor be preferable for this application if using transistors is viable at all? The AIN values can range from 0V to Vref on the ADC.

The circuit I'm considering is like this:

AIN1 ----- Transistor1  -----
                                             |
                                             |--------- ADC Input
                                             |
AIN2 ----- Transistor2  -----


texts:
I'm not clear how (if) NAND EEPROM (made by Toshiba) is different compared to regular NAND Flash memories (except is cheaper).

We want to use with SAM9G device that is support NAND devices such as MT29F2G08AAD.

The NAND EEPROM we found is TC58NVG1S3HTAI0.

Now both share the same interface, package, same voltage and timing is quite the same. However, command list is partially the same so we don't know if it is compatible.

Anyone has used such NAND EEPROMs and can give some hints?
Thanks.


texts: Coupling aluminium electrolytic bipolar capacitors

texts:
Can I use two antiseries electrolytic capacitors to create a non-polarized one, and use it as coupling to the input of an audio amplifier?

I know that electrolytics change capacity as voltage and frequency change, but this doesn't really seem like a problem to me. It's just a DC blocking capacitor.

The voltage also through these is very low, the current is microamps, maximum of 2Vrms.

To make sure they had no problems, I measured their intermodulation distortion with the spectrum analyzer. It seems that even using high frequencies (15 and 18 kHz) for the spectrum analyzer there are no differences in terms of THD or noise with a ceramic or polyester capacitor.

Did I miss the test? Or is it totally ok to use electrolytics for input coupling? And what happens if I use only one polarized capacitor?


texts: Combining single cell LIPO chargers into a multi-cell charger

texts:
I have a 2S lipo battery that I want to charge. Normally, I'd charge it with a balanced 2S lipo charger like this, but for my application, I want to embed the charger in the device, and consumer chargers are too big.

I also don't want to design my own balanced 2S charger from scratch.

I have several super cheap tiny single-cell lipo chargers like this. Is it possible to combine two of these to make a 2S balanced charger?

The circuit I'm thinking of would look something like this:

Would this work? Is there anything I'm missing? Should I put schottky diodes between the charger output and the positive cell terminal?


texts:
How does a resistor "resist" current/potential?

I know it's an elementary question, but I'm sure others are wondering too.


texts: Battery life: 2xAA or 4xAAA - which is better?

texts: Which will provide longer battery life: 2xAA batteries in series or 4xAAA batteries in series regulated to 3V via a voltage regulator or buck converter?


texts:
I'm looking for a symmetric +30/0 -30/0 V protection (overvoltage (+-35 V), undervoltage (+-10 V), overcurrent (4.5 mA) and reverse polarity) for an opamp. I would like a circuit that reactivates himself after some time or when the fault is removed. So, if possible, no fuse.
At first the eFuse seemed perfect but out of stock until a least July...
For the postive part, I figured an LM317 as current limiter and the LTC4365 will do the trick.

And it works!
But LTC4365 doesn't work in the negative part. So if you had any suggestion :)
Thanks for your help!
EDIT: couldn't I use a "inverting switching regulator" connected to the Vout of the first mos regulator ? SOmething like the LT3757 (but with the right specs)


texts: What is purpose of exporting system using tcl scripts generated by Qsys?

texts:
To "Export" a Qsys system we merely need the .qsys file.

Inside Qsys (now called Platform Designer) we have the option where we can export the system as a .tcl script. The options are the in the file menu and these are:

i. Export System as Platform Designer script (.tcl)

ii. Export System as hw.tcl Component

My questions are:

Why do we need these when we can just send off the .qsys file?
Why do we have two options and not just one i.e what is the difference between them?
Is the Qsys system included when we archive a project?


texts: Explain small signal model of bipolar junction transistor to a beginner

texts:
I am a little weak in analog circuits even though electronics is my subject (Engineering course). Transistor is like a Pandora box to me. Last day I read a question about how to use transistor as switch in this site. It made complete sense to me. That gave me confidence to learn more about transistors. I want learn deep about that now. Deep enough so that I can even do analysis myself without referring any textbooks. So please explain me about transistor models in plain English.
I know what transistor is. What I don't know is about it's models for circuit design like hybrid model, small signal model etc. I don't what equations (I got books for that). Tell something in plain language.
EDIT: Explain about Small signal model.


texts: Using a simple RC or RL filter as both high pass and low pass at the same time

texts:
If I had a simple RC or RL filter, and I connected both the high pass output and low pass output to the same output, would the overall output be roughly the same, assuming high efficiency components?

Further more, if I was to connect them to seperation outputs, let's say to two identical speakers with infinite and flat frequency responses,, would there be much difference between the input and output signal?

And if not, what effects from both ideal and realistic components would lead to inconsistencies?

EDIT

After some helpful discussion in the comments, I have been informed that my idea on the Vin and Vout of the circuit is backwards. This is the circuit diagram I had:


texts:
In the three phase induction motor 3 pair poles are used.but
In one phase insduction motor,two poles are used.is it true?
Is Pair of poles indicate the phase .


texts: How to get higher amperage out of a power supply?

texts:
I currently have a 24V - 5A power supply in a commercial product that may require upwards of 8A from the load.  Ideally, I would just hook up another 24V - 5A power supply in parallel and not worry about the overcurrent.  However, I know that this is an issue because of the slight differences in voltage from each power supply (they will fight til one dies).

Is there any way for me to boost the amperage available of this power supply safely without completely replacing it?  Footprint is an issue since this is a commercial system, I have about 4" x 2" of space in my box.

For background, I am a degreed electrical engineer, but did not focus on circuit theory (went more of the emag/nuclear route).


texts: Help in bypassing a defective knob in an airconditioning unit

texts:
I would like to ask for help fixing my airconditioning unit.
Please see image for a clearer picture of my problem.

So I have a defective knob for switching on/off my airconditioning unit.
Since its very old and finding a spare part is hard, i would like to bypass this defective knob.

===========UPDATE # 1==========

Based on my research, i can connect wire 1 and 3 so that it is always ON. (Please see image)
I don't know what to do with wire 2. (It seems to be connected to the thermostat)

Questions:
1. is connecting wire 1 and 3 correct to make it always ON?
2. Anyone knows what to do with the wire 2. (the one connected to the thermostat)

Please see image for list of wires
Wire 1 connects to the capacitor.
Wire 2 connects to the thermostat, air swing switch and fan selector switch
Wire 3 connects to the power cord.

I think that connecting wire 1, 2 and 3 will bypass the defective knob and make the airconditioning unit ALWAYS ON.

Questions:
Does anyone think this is correct or incorrect?
Any theories on how to bypass to make it always ON?
Will anyone think there will be a big problem if I try to connect all 3 wires just for testing purposes?

Thank you. Any help is appreciated.


texts: What type of photo sensor/light combo best for detecting a falling drop of water?

texts:
I am trying to setup a rig for water drop photography. This is where you take a picture as a water drop is impacting against another object or body of water. The trick is to detect the drop as it falls and then use a tuned time delay.

I want to detect when a drop of water interrupts a light source as it falls. The most important factor is that it be repeatable. I need it to respond to the interruption consistently. The sensor also needs to be fairly quick as the drop only interrupts the light very briefly.

I have seen photo resistors, photo transistors, and even photo diodes. Which of these or other parts would be best for my use?

What sort of light is best? Should I use a laser or IR or something else? Water is clear in normal light which could be problematic, is it clear in all spectrums?

How do I deal with ambient light? I have heard that by pulsing the light source at a known frequency it can be differentiated from surrounding light.

I am basing the project on an ATMEGA328 but am happy to add other parts to work with different sensors. I am also interested if anyone has a solution other than light based sensors.


texts: Electric shock from outdoor security cameras

texts:
I just bought this outdoor security camera kit from Amazon.

(Amazon product link)

When wiring it up, I noticed that I got a small sharp shock when touching the small screws on the metal casing around the cameras. I was wondering if this should be considered dangerous, or is this perhaps just static electricity?

The cameras are powered by a standard looking 12V power adapter.

I've added a photograph of the rating on the adapter here:

(Original image link)

Could something else be causing the shock? I fed the cables through an existing hole in the wall, so they sit alongside an existing power supply for outside lights. I wonder if this could be causing an issue?

Thanks!


texts: What determines the ground state of a computers dram?

texts:
I have read a paper about the cold-boot attack led by J. Alex Halderman.
Full pdf: https://jhalderm.com/pub/papers/coldboot-sec08.pdf

The paper shows the decay of a data in memory without power. They used this picture as example:

Obviously, the discharged state for some capacitors are represented as 1(white) others as 0(black).

What is the reason for this? Why not represent every discharged capacitor as 0? Can you give me some insight in this topic, or keywords I can further research?


texts: Feeling a tingling sensation by touching stuff, Is this safe?

texts: I'm putting on my desktop computer on steel rack as usual. A while ago, when I touch the steel rack for seconds, practically I feel a tingling sensation, sort of electrical shock in my finders. After that I measured how voltage the steel rack has, the multi-tester meter indicated almost 50V by AC mode. Is this safe to touch or keep the PC on the position, or I should get away the PC somewhere electricity-safe? I'm not sure this site is suit for asking this kind of question, but I'm very worrying whether this is safe or not since this experience is my very first time. Thank you.


texts: Powering Arduino + raspberry pi 3 using one voltage source(Battery)

texts:
Hello I am making a simple car robot, which required a raspberry pi to be connected with Arduino using usb cable
My question is how to power them up using one voltage resource which is a    2 batteries (3.7v 9900mA  for each batterry)


texts: What do you mean by endurance of a capacitor?

texts: What is the role that endurance of a capacitor  plays in circuit design


texts:
As question asks. What is a flow table? How is it different from forwarding table?
This link says:

Switching = forwarding by destination MAC
Routing = forwarding by destination IP
Forwarding = Forwarding by Flow.

and this video gives idea that a flow table is a forwarding table based on rules decided by controller. Not like forwarding based on IP or MAC.
If I am wrong correct me or add useful comments.


texts: Explain Voltage/Current Basics with LEDs Example

texts:
I am using a Nokia mobile charger that can output DC 5V at 350mA. I am connecting a 63 LED panel (salvaged from an old emergency light) to the charger directly, and the LEDs glow. I removed all the circuits from this emergency light, and only kept the LEDs panel, connected directly to the charger.

From what I know, an LED needs about 20mA of current, so 63 LEDs in my setup will need 1260mA of current. The charger I am using only outputs 350mA. How are the LEDs still glowing fine? What is happening here?

Basically I want to know what will happen in these cases:

1) If the item draws more CURRENT than what the power source can provide, what will happen?

2) If the source can provide more CURRENT (say if I switch to a 2A charger) than what the LEDs can consume, what will happen?

PS: I just play with these things, so my knowledge in this area is very limited.


texts: Three Different Voltage Lines, Same Common Ground?

texts:
I am trying to send PWM, clock, latch and blank signals from Arduino through a series (16) of TLC5940 Breakout boards and on to a grid of 512 individual controlled LEDs six feet away (RJ45). I am using op-amps to help get the serial signals pushed through the large number of boards. Power and Ground are in parallel.

Of course, I am having problems. The set-up, as pictured, works well until the 9th or 10th board, then things get wonky. They are getting power but not individual control -just flickering.

I am trying to troubleshoot. The whole thing is powered by 12 V, 30 A switching power, buck converters for three different voltages (10 V for Arduino, 4.7 V for op-amps, 6V for boards and LEDs).

I am wondering if I should tie all grounds to a single common line back to the power source (V-) or do the individual voltages (10 V, 4.7 V, 6 V) need their own ground line back to power source? Example: the five op-amps - 4.7V+ and 12 V- single line common ground? - or should they have their own ground line all wired back to the 4.7 V converter and its 4.7 V-?


texts: Can i replace a De-9 port with something else?

texts: I was given an old piece of DJ equipment from the late 90s and unfortunately, the only way to connect it to a pc, which is what its meant for, is through a De-9 port/cable. And my pc doesn't support that. I could, in theory, buy an adapter but I'd prefer not to so I was wondering if I can either make an adapter or somehow solder a different port type in place of the de-9. If it's not possible I'll just scrap it for parts for future projects but I want to at least see if it can be used. Even if I can replace it though it probably won't be useful since the software is for win 98 and Windows 10 doesn't support that as far as my knowledge goes


texts: How can I hack a Bluetooth mono headset into a speakerphone?

texts:
I tried adding a speaker but the audio is too quiet for obvious reasons. I would like to use an 8ohm seapker and i think the headset uses a 32ohm earbud speaker.

What kind of amplifier would I use?  I would like to use the same 3.7v that powers the headset and tried LM386 but couldn't use the same battery source. I want to use as few parts as possible.

Thanks!


texts: I was studying about 8259A from the Intel documentation of Intel 8259A. What I came across was that the Read/Write Logic has an input from control logic.In all other ICs that I have seen, this is shown the other way round. Plus, I see no output pins in the R/W logic block. So what is that input for? Or is it a typo?


texts:
I'm using a cypress microcontroller to read some values from the FT201XS-R chip. I can get acknowledgment, but I can't seem to read. Here's the datasheet.
I'm attempting to do a read of register 4 of the MTP memory as outlined on page 39 of the datasheet.

Here's my code

int main{

    uint8 addr = 0x22;
    uint8 WriteBuffer[16];

    UART_1_Start();

// I added this because the I2C will be pulled low by a slave when addressing goes wrong. This helps to make it still work
    while(I2C_1_sda_Read() == 0) // SDA hang low
    {
        I2C_1_SET_I2C_SCL_HSIOM_SEL(I2C_1_HSIOM_GPIO_SEL); //Switch to GPIO
        I2C_1_scl_Write(0);
        CyDelay(1);
        I2C_1_scl_Write(1);
        CyDelay(1);
        I2C_1_SET_I2C_SCL_HSIOM_SEL(I2C_1_HSIOM_I2C_SEL); //Switch to Component
    }

    WriteBuffer[0] = 0x10; // this is the address mtp signal
    status = i2c_send(0x00,WriteBuffer,1u);

    WriteBuffer[0] = 0x00;
    WriteBuffer[1] = 0x04; // this is register 4
    status = i2c_send(addr,WriteBuffer,2);

    WriteBuffer[0] = 0x14; // this is the mtp register read value
    status = i2c_send(0x00,WriteBuffer,1u);
    readData = i2c_recieve(addr);

}

uint32 i2c_send(uint8 addr, uint8 * data, uint8 count){
    uint32 status=1;
    uint8 i =0;
    uint8 check;
    I2C_1_I2CMasterClearStatus();
    status = I2C_1_I2CMasterSendStart(addr, 0u);
    while(status){
        I2C_1_I2CMasterClearStatus();
        I2C_1_I2CMasterSendStop();
        CyDelay(10);
        status = I2C_1_I2CMasterSendStart(addr, 0u);
    }

    for (;i<count;i++){
        check = *(data+i);
       status = I2C_1_I2CMasterWriteByte(*(data+i));
    }

    I2C_1_I2CMasterSendStop();
    CyDelay(10);
    return status;

}

uint8 i2c_recieve(uint8 addr){
    uint32 status;
    uint32 readData;
    CyDelay(10);
    status = I2C_1_I2CMasterSendStart(addr, I2C_1_I2C_READ_XFER_MODE);
    while(status){
        I2C_1_I2CMasterClearStatus();
        I2C_1_I2CMasterSendStop();
        CyDelay(10);
        status = I2C_1_I2CMasterSendStart(addr, I2C_1_I2C_READ_XFER_MODE);
    }
    readData= I2C_1_I2CMasterReadByte(I2C_1_I2C_NAK_DATA);
    I2C_1_I2CMasterSendStop();
    return readData;

}

I am able to do all of the I2C send commands, but when I try to do an I2C recieve, the status hangs on 2, which is the SCB_I2C_MSTR_NOT_READY error. This corresponds to this description:

  Master is not ready for to start transfer. A master still has not
  completed previous transaction or a slave operation is in progress (in
  multi-master-slave configuration). Nothing was sent on the bus. The
  attempt has to be retried.

What do I need to change to get the register read to work?

EDIT ***************

I created a new function to perform the read

uint32 i2c_read_mem(uint8 addr, uint8 reg){
    uint32 status=1;
    uint32 readData;
    uint8 i =0;
    uint8 check;

    status = I2C_1_I2CMasterSendStart(0x00, 0);
    status = I2C_1_I2CMasterWriteByte(0x10);
    status = I2C_1_I2CMasterSendRestart(addr,0);
    status = I2C_1_I2CMasterWriteByte(0x00);
    status = I2C_1_I2CMasterWriteByte(reg);
    status = I2C_1_I2CMasterSendRestart(0x00,0);
    status = I2C_1_I2CMasterWriteByte(0x14);
    status = I2C_1_I2CMasterSendRestart(addr,1);
    readData= I2C_1_I2CMasterReadByte(I2C_1_I2C_ACK_DATA);
    I2C_1_I2CMasterSendStop();
    return readData;

}

With this function, I2C no longer hangs, but it always returns 0. According to this document, I should see the usb vid at byte 2 and 3. yet when I run

for (i=0; i<20; i++){
        readData = i2c_read_mem(addr, i);
        CyDelay(1);
}

all values returned are 0.


texts:
I used the guide at https://vetco.net/blog/test-a-transistor-with-a-multimeter/2017-05-04-12-25-37-07 to test a transistor with my DMM. The NPN transistor I used to test is the "mospec tip130 No11D" and it was off from the circuit.

My question is that, STEP 3 (Emitter to Base) failed to show “OL” (Over Limit). Instead I read about ~1.2V. I used another same transistor that I am sure that it works on the circuit and I still get the same reading. Is the transistor a) bad b) wrong test c) good for some reason ?


texts:
I am trying to follow filter design scheme proposed here.

The paper draws an analogy between electrical and mechanical filters.

I think understanding this paper boils down to understanding equation (1)

\$ -1 \leq \frac{Z_1}{4Z_2} \leq 0 \$

and Fig 1

I understand that the three schematics correspond to three different ways you can break up the building block (unit) of the general scheme.  I am not sure what \$Z_{iter}\$ represents and how they got the expressions in terms of \$Z_1\$ and \$Z_2\$


texts: Flyback converter for a step-up application (4VDC to 48VDC)

texts:
From what I have seen, flybacks are used for step down applications, are step-up applications possible? More specifically, is converting from 4VDC to 48VDC possible using a 1:8 transformer?

I'm designing a converter from scratch (no COTS controllers); and I need to step-up from 4V to 48V. I am trying to leverage the turns ratio of the transformer (currently a 1:8).

In a typical boost converter configuration, current is continually drawn from the input; but that is not the case of flybacks. Flybacks push packets of energy kind of like buck converters; they store the energy in the magnetizing inductance during the switch ON; and push out during the off cycle. The input current is discontinuous.

This discontinuity has me thinking there are limitations of the flyback topology that I am not thinking of.

For reference:

Edit:

I am confident in solving the controls compensation, EMI/voltage-spikes, and magnetic challenges.

Edit 2:

power would be <10W


texts:
I'm into DIY module-making for modular synthesizers. I came across this stripboard layout from the musician Look Mum No Computer for a module that will take an input signal (usually ±5V range of any shape via the "CV IN" jack), pass it through an ADC, and return high/low outputs corresponding to bit value, which can be used for various applications in modular synthesis.

I've made the circuit and it operates great. Just one problem, when the input signal drops into negative voltage, the ADC does not generate any outputs, which is an inconvenience as the module only works half the time, in essence.
My idea for fixing this issue was to add a bridge rectifier to the input signal coming in from the "CV IN" jack, thus ensuring that the input signal always stays positive. Although I am unsure exactly how I would go about adding this. The circuits for bridge rectifiers that I have looked at in the past require a positive/negative input and generate a positive/negative output, and "grounding" these negatives to each other negates the effect of the bridge rectifier. The jacks are also mounted to a metal plate, which is grounded to the GND line. For clarification, the bridge rectifier would be added between the "CV IN" jack and the green wire.
So my question is, can you add a bridge rectifier to this circuit and if so, how exactly? Or is there another way to essentially take the absolute value of the input signal coming in via the "CV IN" jack?
If clarification is needed, please ask, will be happy to provide more info.


texts: Preventing inadvertent feeding of an external watchdog

texts:
Most internal watchdog timers found on microcontrollers contain mechanisms to prevent an inadvertent feed, usually requiring the write of a specific key-value to the feed register, although some watchdog timers may require a more specific sequence (of multiple key-values written in order to the same address, or writes to multiple addresses).

However, not all applications can use an internal watchdog, for reasons that are detailed well here, and thus use an external watchdog instead.  However, these external watchdog timers are fed by toggling a single pin on the IC.  Simply hooking this up to a port pin is a solution I perceive as mishap-prone, where a write to other pins on the GPIO port could inadvertently feed the watchdog.  While a windowed-watchdog provides some defense against premature feeding, relying on it as a sole defense against such is unwise from a defense-in-depth standpoint.

What strategies can be used to prevent inadvertent feeding of an external WDT, given that currently available external watchdog ICs use a single pin for their feed input, instead of a serial or parallel bus input?  Hardware strategies are preferable, although software defenses against inadvertent feeds can be useful in a defense-in-depth strategy as well.


texts: Issue with step-down converter feedback and where to place it

texts:
so I figured out where the buzzing is coming from in my circuit, and I think I'm starting to see the problem with it.

Here is a schematic I have:

The DC/DC step down converter I'm using: http://www.ti.com/lit/ds/symlink/tps54531.pdf

So what this is doing is charging up a super capacitor fairly quickly at 5.6V on the output, and since my feedback is after the current-limiting resistors, I realized now that when the capacitors are fully discharged, I'm essentially shorting the post-resistor node.

So the converter is trying to upkeep a 5.6V after the current-limiting resistors (which at that point is basically ground) which makes it run at full throttle. Not good!

My question is, would moving the feedback before the current-limiting resistors help? What I'm kindof unsure about is since the capacitors are essentially a short to ground at no-charge, would the capacitors initially see no voltage on the input, since it is all dropping across the current-limiting resistors?

Or, would this be compensated by residual charge and the capacitors still charging with some small current and raising the voltage?

Thanks :) If there is some other solution please let me know!!


texts: How do I connect a signal shield to minimise noise from close proximity AC

texts:
In my proposed application, I will have approximately 30 RS-485 nodes configured in 3 chains spaced ~1m apart. There is a need to pass through 240v L-N-E, +5v, A, B, GND in each node. The physical layout is shown below, as well as an example of the cable.

I am worried about the interference on my signal lines. There will be approx ~1.6A Triac switched current on each chain.

How do I connect the the signal shield to offer the best protection?


texts: Is it possible to make my own charging cable?

texts:
I have a heart rate monitor that uses a proprietary charging cable - that I have misplaced.

The charging area looks like this:

Is it possible to use an existing micro-usb cable and hack it to make this charge?


texts: Which RF comms solution allows unidirectional short distance low data rate, low latency communication to the largest amount of receivers?

texts:
I'm interested in delivering 3 bytes to a bunch of recipients roughly every 50ms with a single transmitter. The data sent is unique to each recipient. I am curious which existing wireless comms solution would allow me to achieve the largest number of recipients I could deal with this way.

I've thought about BLE (which would be pretty great because ideally the recipients are also energy contained) and with it the limiting factor seems to be the connection interval. The lowest CI in BLE is 7.5ms which limits the theoretical number of devices I can send unique data to in 50ms to 6. I'm thinking that there must be a solution out there which doesn't penalise switching recipients as much as BLE. Or should I be looking into a custom protocol?


texts:
In a post regarding heat dissipation in a linear regulator, one answer provided this nice little pin-equivalent smps. It was a great reply, and I'll likely order a few myself.

I am wondering though, why is there so much empty space? It doesn't appear to need extra layers - except maybe a ground - and it looks like it could be far more compact.

Is there something going on that is not obvious from its appearance?

edit: to be clear, I was not the OP for the linked post. Just borrowing it for this follow-up question.


texts: Interfacing LAN9512 or LAN9514 to KSZ8895 Ethernet Switch for Raspberry Pi Compute Module 3+

texts:
I would like to add Raspberry Pi Compute Module 3+ to my design.
My design has an ethernet switch KSZ8895 on board. The 5th port can be configured for using MII.

It is known that the Compute Module (CM) provides Ethernet and USB via an IC. It is mostly LAN9512 or LAN9514. But, I am not sure whether I can directly interface LAN951x to one of the ports of KSZ8895. I don't want to use RJ45 to RJ45 connection to the switch via a short UTP cable, it is not desired as you may understand for a custom design.

I am also open to any other alternatives to LAN951x if it would be better for interfacing to KSZ8895 while still providing internet to CM. In this case, I can volunteerly sacrifice USB option which LAN951x provides.

A piece of schematic from the switch circuit;

if possible, I like to interface KSZ8895 without transformer H1102NL.


texts:
I want to sense a switch being closed or opened in a scenario as given below:

The switch is about 50 feet away from the MCU. Round trip becomes 100 feet. Also, the wires are not twisted pair and they are laid along with 220 VAC lines which will be powering all sorts of household appliances ranging from a mobile phone charger to an air conditioner. There will be multiple phases since it's a 3 phase 4 wire house wiring.

Will this circuit work? Is there some minor and inexpensive modifications that will make the circuit work?

MCU is using non isolated power supply and I can use neutral or 220 VAC live line as my GND reference. Will that help?


texts: Problems solving strategies of experts in simple DC-circuit problems

texts:
There are many papers which study how students in high school and college think, when solving elementary DC-circuit problems. However I don't know any resources where the reasoning of experts is described in detail when solving such problems.

I am only interested in qualitative (circuits with batteries and light bulbs)- problems.

Consider for example the following question about the circuit below:

How does the brightness of the bulbs \$\mathrm{L}_1\dots \mathrm{L}_3\$ change when the switch is closed?

My first question is, if there are any resources where the qualitative reasoning of experts in solving problems like this, is documented in detail.

My second question is, how you as an expert would proceed in detail to solve  the example problem above.


texts: How to combine a LPF and a Voltage divider?

texts:
I have to connect a 5V analog signal to a 3.3V MCU analog GPIO input as shown in the attached image. I wonder if its possible to combine the 2 blocks of voltage divider and RC-LPF into a single block? Is it possible to reduce the 3 resistors to 1 resistor? If possible then how to calculate the resistor value?

Edit:

The values shown in image are not real. The cutoff frequency I intend for the LPF is anything around 2k Hz


texts: Do fuses affect a PC PSU's amperage output?

texts:
I have a PC PSU powering a load that should pull 20 Amps. I put a 10 Amp fuse in series with the load and the PSU. However, the fuse simply will not burn, and the PSU continues to supply the load, albeit at a weaker output (the load doesn't operate as quickly as without a fuse).

Is the PC PSU somehow accounting for the fuse and lowering its output? I'd appreciate any input.


texts:
I'm designing a circuit which has a bluefruit nrf52832 micro controller built into it. When referencing the schematic provided by Adafruit I noticed that they had +VBAT going to the drain of the p-channel FET. Does anyone know why this is? Is there a reason or does it not matter/just a mistake on the schematic?

Link to bluefruit:
https://www.adafruit.com/product/3406

Schematic provided by Adafruit:


texts: Lowest latency out of the 802.11 Wi-Fi standards

texts:
I'm making a project using an Arduino and an ESP8266 module running the esp-link firmware - which gives me the ability to use MQTT for controlling the Arduino. I'd looked at something like an XBee module instead - but they're so damn expensive compared to the ESP8266! (If you don't know what ESP8266 or MQTT is, don't worry - it's enough to know that it's using TCP over Wi-Fi).

The MQTT packets are tiny, so the throughput of the Wi-Fi network is never going to be an issue. But, latency and reliability are large factors. The MQTT system is using TCP, so it should be reliable enough - but I'm not so sure about latency.

I have the choice of using an 802.11b, .11g or .11n connection for the network the ESP8266 uses. Is there anything in any of these standards that makes one have lower latency than any other? Which would I expect to have the best performance with for very small and infrequent packets?


texts: Generating video with ZYNQ, using IP block design?

texts:
I am trying to implement a video streamer on Digilent ZYBO board that has Xilinx ZYNQ 7010. By the way, reason of this thing is to test the quality of an encoder board. What I want is to:

Generate a RAM Block to store pre-determined video data.
Stream out its contents from Pmod connectors (probably using AXI4-Stream Video Out block), using DMA.

Video features are: 1024x768, 720p, 30fps for now. I may have to change them later.

I have found some design on web (please check the figure below). But since it generates random video, I have to modify (I mean, replace it with some other blocks) Test Pattern Generator block, but I have no idea how. What kind of design process should I follow? I have limited time and knowledge about block designing and HDLs, so any help is appreciated.


texts: Efficiently driving 8 low-current Optocouplers

texts:
I'm looking to drive a bank of eight FOD4216 random phase triac drivers. I'm looking specifically at the (insanely expensive, $3!) Fairchild FOD4218, which needs 1.3mA to switch. 8 * 1.3 = 10.4 mA total draw for the bank of 8.

My uC can only sink/source 5mA, so I need some way to drive my optocouplers. I'd prefer to keep as low powered as possible, but a focus on minimizing the number of components leads my concerns. Somehow I need to get my uC from sourcing the whole 1.3 mA per optocoupler, down to sourcing no more than .625mA (5mA/8units = .625/unit) of the 1.3mA drive. Some headroom past that for the uC would be good. What would be good ways to create these 8 optocoupler drivers?

Not sure if it's helpful in doing the maths here, but forward voltage drop in the emitter appears to be between 0.9 - 1.2V across the full range of temperatures.


texts: How can I connect many brushless motors to a big battery pack instead of using a separate small pack for each motor?

texts:
Usually brushless motors comes with indications on how many batteries you can connect to them, it is common to to see 2x3 battery packs where each battery provides 3.6 Volts or so to power a single brushless motor. However I fear things are not that simple when putting much more stuff in parallel.

Let's assume I have a battery with

9000 mah
210 grams weight
rated 10C
3.7 Volts working
2.8 Volts discharge cutoff

If I want to operate a brusheless motor at 7.4 volts I have to put 2 batteries in series, then if the operating current for the motor is 10A, with a 15 A ESC connected to it, then the motor will run for about 54 minutes) in theory (in reality it would be less due to infinite factors).

However if I setup 10 brushless motors, each one with 2 batteries, every motor will run at most 54 minutes, but due to motors each running at  slightly different powers, some motors will ends power sooner than others, and they will turn soon into extra useless weight for the drone.

If I want to share all the power across all motors to avoid some stuff turning suddendly into dead weight, I have to setup an array of batteries with 2 rows in series, and 10 in parallel (20 total batteries).. Is there any extra precaution to use compared to a regular parallel light bulbs?

The theory behind my question is that if I put motors in parallel and batteries in parallel, I can view motors as resistances, in ideal world each motor would absorb same amount of current, but motors do not have constant resitance, which makes me fear that under some conditions I could actually burn my motors or my batteries by providing much more more power putting so many batteries in parallel.

As long as I burn a single battery or a single motor it is fine, but If doing this is wrong I could actually burn a lot more motors and batteries: lot more money gone. That's why I'm asking to experts.

I have no degree so far in any electric-related stuff, I'm learning everything from internet so I'm sorry If I'm not asking the question in the best possible way.


texts:
I've just started learning microwave transmission in my engineering course.  The question that has been hovering over mind is "why do we need transmission lines (conductors) to transmit microwaves when we already know that microwaves can be transmitted wirelessly?"
I want to know like, what is the relation between these conductors and the EM wave (ie. microwave.)


texts:
I want to count pulses using PIC16f877A. The pulses are being fed into pin RA4. I want to use timer interrupt for that so that other functions performed by the micro controller should not disturbed. The frequency is displayed on a LCD Screen.

I want to understand the programming. What happens when a pulse of frequency signal reaches at T0CK1 pin of the PIC16f877A. Will it cause an interrupt? So should I define interrupt for that? Kindly help me with Mikro C code.

Here is the code as it stands:

//Timer 0 will count and Timer 1 will measure 1 second time using interrupts ; mikro=16f877a
// OUTPUTS

#define led PORTB.F2

sbit LCD_RS at RD5_bit;
sbit LCD_EN at RD4_bit;
sbit LCD_D4 at RC4_bit;
sbit LCD_D5 at RC5_bit;
sbit LCD_D6 at RC6_bit;
sbit LCD_D7 at RC7_bit;

sbit LCD_RS_Direction at TRISD5_bit;
sbit LCD_EN_Direction at TRISD4_bit;
sbit LCD_D4_Direction at TRISC4_bit;
sbit LCD_D5_Direction at TRISC5_bit;
sbit LCD_D6_Direction at TRISC6_bit;
sbit LCD_D7_Direction at TRISC7_bit;
//=======End LCD Connections=============================================
unsigned int x=0,frq=0, cnt=0;

void interrupt()
{
 if(PIR1.TMR1IF)
 {
 T1CON.TMR1ON=0; //stop
 TMR1L=0XEE; // <------------- reload the timer
 TMR1H=0X85;

 if(cnt>=4)
 {
 led=~led;
 frq=1;
 cnt=0;
 x=tmr0;
 tmr0=0;
 }

 //frq=1;
 PIR1.TMR1IF=0; // <------------- clear the timer interrupt flag
 }

}

void main()
{
 OPTION_REG=0xA0; // for timer 0; NO presscaller; counter mode at T0CKI
 T1CON=0X60; // 1:8 prescallar, timer off
 ADCON1=0x07; // adc reg initialization ; changes port a to digital I/O
 INTCON=0x80; // globle interrupt enabled
 TMR1L=0xEE;
 TMR1H=0x85;
 T1CON.TMR1ON=1; // timer on
 PIR1.TMR1IF=0;
 TRISA.f4=1;// making ra4 as input

 x=0;
 frq=0;
 lcd_init();
 Lcd_Cmd(_LCD_CLEAR); // Clear display
 Lcd_Cmd(_LCD_CURSOR_OFF);
 Lcd_Cmd(_LCD_MOVE_CURSOR_RIGHT); //*/

 Lcd_Out(1,1,"Frequency");
 while(1)
 {
 if(frq==1)
 {
 Lcd_Out(2,2,X);
 Lcd_Out_CP("Hz");
 frq=0;
 }
 }

}


texts:
I need to activate a 12VDC, 8A diaphragm pump with the output of a PIC16F628 (5VDC, 0.025A maximum). The standard way to do it, as I learned in college, is to saturate a transistor that will drive a relay, that will activate the pump.

Now I am wondering if I could do it with a high current darlington NPN transistor driving the pump directly, like this:

simulate this circuit – Schematic created using CircuitLab

Is it possible and/or viable? What are the advantages and disadvantages of this compared to using a transistor driven relay?

Is it easy to find a transistor with the required characteristics? 10A Ice, with gain from 0.025A Ibe to about 20A Ice (needed at pump startup, before stabilizing at 8A Ice). Is there such a device? From the datasheets I find on Google, the higher the Ice, smaller the Hfe, so that I can't drive a high peak current from the PIC...

By the way, what is the voltage drop from base to emitter I must consider in order to dimension R1?


texts: Can I use MOSFETS instead of transistor in the given circuit

texts:
I am modifying an electronic transformer as an irregular power supply as shown in the image below.
I am not able to find 13009 high power transistors.
Can I use two IRFP460N power MOSFETs in place of them?
Do I have to change anything else?


texts: What is the "nominal temperature threshold" (NTT) on a thermistor?

texts:
I bought a thermistor together with my Arduino, because I thought it would be a good first project. I should have gone a different way, since it is obviously too complex for my level, but well, now I have got it, and I am trying to understand it, so I hope you can help.

It is an Epcos, PTC thermistor, from RS-Online (link). The datasheet (link) shows the following charts:

Why are there seven different graphs (NTT = 60, 70, 80, 90, 100, 110, 120°C)? The only possible explanation I can think of is that the thermistor comes in severen different versions with each their NTT, and I have one of them (without knowing which one). Is this correct, and if not, then what is this NTT?

NTT is short for "nominal temperature threshold", but little shows up when I Internet search for it.

The text on the thermistor says D801 A80. Perhaps the 80 means that it has NTT = 80°C?


texts:
I am trying to understand how amps work exactly. I see variations of the following in various online sources.
From here:

[...] A standard household circuit that supplies your outlets and switches carries 15 or 20 amps (15,000 or 20,000 mA).

And:

This gives you an idea of just how much danger there is in the home wiring system we take for granted, where wires carry 15,000 or 20,000 mA.

Also, from this question (only the wording in the title is relevant for my question):

Is lithium battery charging speed proportional to the amps provided from the power source?

To me, this means that a power source has a fixed number of amps that it provides, similarly to how it has a fixed voltage that it provides. This number of amps is always there, like the voltage is always there.
However, from here:

[...] For example, if you have a 100-watt light bulb in a lamp that is plugged into a 120-volt outlet, it will draw 0.83 amps.
[...] For example, if you plug a 40-Ohm dryer into a 220-volt outlet, the appliance will draw 5.5 amps.

So this makes it sound like if you plug the above dryer in, the wires won't carry the full 15A mentioned in my first link, but will only carry 5.5. The 15A is an upper limit, not what's always there.
Which is it? is the 15A always there, or is it just an upper limit, and what's there is only what is being drawn by a consumer at any given moment?
If it's the second, then, although I am aware that it's dangerous and I have no plans of trying it out, I don't have a clear idea about HOW dangerous exactly. How much would a human body (let's say with a dry finger) touching the wires draw? 100mA? 1A? the full 15A?


texts:
I recently made my first PCB.  I ordered it from China and soldered it up on my homemade oven, and it's working awesome.

I've already started a list for rev 2.  There is one issue that I'm hoping I can get some experienced advice on.

Here are pictures of my board, and a GPS module from Uputronics.  I've done a lot of testing, and the module from uputronics is consistently better.  It locks in about half the time, it picks up more satellites, and the satellites both modules pick up, the uputronics gets about 10 dB better signal.

Is there any tips or guidance I can get for how to make my GPS antenna layout better?  10 dB seems like a lot, is there some important rule that I'm overlooking?  Any help I can get so I can make rev 2 of my board as good as this module would be much appreciated.

Thanks in advance.


texts:
I'm facing issue with IR2110S driver while driving 3 winding BLDC motor (24V, 8A rating with Hall sensor feedback) using IFR3710 MOSFET (half bridge configuration).

Issue:

When varying duty cycle from 0 to 95 present with 5 percent interval, motor running fine. But when varying duty cycle (PWM) from 0 to more than 50 percent suddenly, IR2110S driver IC getting failed sometime. there is no IC heat observed. MOSFET not get damaged. after replacing IC its working fine with 5% duty cycle increment.

With driving the motor, observed some spike on low side MOSFET drain and source terminal. I think low side output section of IR2110 driver circuit failed. This will fail when LO pin voltage with respect to ground less than 0.3V and more than VCC+0.3V. After driver failed, 555 timer IC threshold and discharge pin varying continuously from 0 to 5 voltage linearly and RED gets turned ON then we are stopping low side MOSFET PWM signal.

Schematic diagram:

Operating condition:

50 kHz switching frequency
24 V, 8 A bldc motor
24 V input power supply to board (main board)
0.05 ohm external resistor board which has 10 cm distance between main board.
Maximum duty cycle should be 90 percent. I want to spinsup directly 0 to 90 percent.

Observation:

I read relavent answer to "Driver failure when driving IRF3710 mosfet using IR2101 driver" question, which is same like my schematic. Difference is current sensing circuit, 4.7 uF bootstrap capacitor (in my circuit, using 47 uF electrolytic), 50 kHz switching frequency. Gate to source resistor.

Am having doubt on following,

1) Is 47 uF electrolytic and .1 uF ceramic decoupling capaictor enough for my load?

2) Switching frequency is 50 kHz, 47 uF bootstarp capacitor is ok or due to high frequency can I reduce it to 4.7 uF for quike charging and discharge?

3) I plan to use 15 V working voltage, unidirectional TVS diode across gate and source of all MOSFETs to maintain 15V max across all MOSFET G-S terminal. If this is OK then voltage rating is fine for TVS diode?

4) Is external sensing resistor long return path will affect driver performance(10cm length wire connected to external having two 0.1/5W resistor parallel connection)?

5) In driver application note, driver COM pin connected directly to lower side MOSFET source pin. But i connected through sensing resistor which is connected externally (due to lack of space in main board). I plan to remove resistor and connect COM pin directly to Low MOSFET source pin. Is that OK (removing current sensing circuit)?

6) Motor control has three phase sequence, we not found cross conduction condition, so not provided dead time delay. Is this will affect?

7) Is the TVS diode across 24 VDC supply rail is required?

Please provide me the suggestion to resolve this issue.


texts: Avoiding mechanical shock damage on a PCB

texts:
I'm currently working on a PCB design that will have to go in a plastic enclosure.

This plastic enclosure will have to endure severe shocks (dropped from 2m to ground) so I'm looking for ways to reduce the mechanical shock transmission to the board to prevent electrical failures.

I've looked at some catalogs of electromechanical components, searching for "rubberised" spacers or similar, but it seems that experienced electrical engineers don't use these kinds of solutions.

What are the best practises/elements to set-up for reducing shock induced stress in a PCB?


texts:
A USB-C has this characteristic shell (the outermost visible metal part). Would the connection still work without any problems if i were to remove the shell (given that all the pins still line up)?
For example in the new MacBook Pros the shell of the USB-C ports melt seamlessly into the chassis which is what i'd want to achieve.


texts: What is the Voltage output of this Unity gain amplifier?

texts:
This Unity gain op amp has a ac supply in line with the resistor to the positive terminal of the op amp. What is the formula to obtain the output voltage?
My challenge is the additional resistor otherwise if it wasn't there then I know that Vin = Vout


texts:
I have a device with multiple USB inputs wired in parallel (Raspberry Pi 2B with Kedei Display, each of the units has an Micro USB input).
Are there any dangers of connecting both inputs at once, powered by different powerbanks/chargers?
I don't want to do this to increase the supplied current, but rather to swap power supplies without having to turn off the device. So e.g. the connected powerbank is about to run out of power, so I connect a wall charger to the second port and then disconnect the powerbank.
Are there any possible negative interactions between the two power supplies? (e.g. different ground potential (especially with two wall chargers), slightly different voltages that cause power to flow in the wrong direction, different voltage fluctuation frequencies from the regulators in the power supplies that cause problems, ...)
Related questions
While this question seems similar to other questions posted on electronics.stackexchange.com, those questions are quite different in some aspects.
Higher current draw from powerbank?
Parallel connecting USB power for higher currents
Both of these questions don't actually use different power supplies, but instead multiple ports on the same powerbank. Also both of them do that, to increase supplied current.
USB power in Parallel, increasing the maximum current using a Y splitter idea[POWER ONLY]
This question actually talks about two different power supplies, but also here the idea is to increase current.


texts: Why is using a single phase device across phases of a 3 phase outlet OK?

texts:
My friend connected two wires to two "non-earth hole" in a 3 phase outlet (208V) to run a 220V single phase blower (Note: the outlet has four holes, one of them is earth). Basically, he used the potential difference of those two holes. I don't know why it is OK, so I used MATLAB to draw 4 curves (See picture)

Blue - regular sine wave 208V (peak is 208*sqrt(3)) where sqrt(3) is three phase peak ratio

Red - Same as Blue but with 2/3 pi shift

Green - The difference between Blue and Red

Black - regular sine wave 220V (peak is 220*sqrt(2)) where sqrt(2) is single phase peak ratio

=======================

Officially, the green peak is >1.73 times the blue one. If the blower uses 220V single phase AC, then the blower should be connected to

----calculation process-----

Peak voltage of 220V AC = average voltage*single phase peak ratio = 220V*1.41 = 310.2V

Peak voltage of two legs out of three phase = (two legs potential difference from diagram)average voltagethree phase peak ratio = 1.73*average voltage*1.73 = 3*average three phase voltage

310.2/3 = 103.4V

-----end of calculation process----------

103.4V  three phases power outlet (Two holes of a 3 phase outlet). Note: I understand that there is no such 103.4V three phase power outlet.

====================

Am I right?


texts: Seven segment display becomes dimmer as more segments are lit

texts:
I've got a common cathode, two digit seven segment display (LDD-N512RI-RA) hooked up to the GPIO pins of a microcontroller (Coldfire MCF52233 DEMO). The problem is that the brightness of the display varies with the number of segments lit. As more segments are activated, the display becomes dimmer. From what I've read, this happens if you try to use a single resistor for the common cathode instead of using one for each anode. However, I am using one for each anode.

I have very little experience with electronics and know very little about electricity, unfortunately. So until I learn more (which I want to do), I can only guess what the problem might be. In the meantime, can anyone suggest what is going wrong here?

More information: The GPIO pins provide 3.3V. The forward voltage/current of the segments is 2.2V/10mA. I'm using 100 Ohm 1/2W resistors for each of the segments. I've got the common cathodes hooked up to GPIO pins as well, and I set the pins to the cathodes to low to activate the displays (I'm not sure if that is the correct way to go about it.). I am alternating between displaying the left/right digit using a high frequency timer interrupt, which I realize may not be the best way to do it. I am already using the timer interrupt, though, so I hoped that I could tack on some simple digit alternating logic without a problem. The board is powered via a USB line to my computer. I'm happy to provide any other relevant information, just let me know exactly what is relevant.


texts: Does Fibre Optic Cabling have any potential for noise?

texts: After Google searching "Do Fibre Optic Cables attract any noise", most results return that they attract virtually no noise. Is this the case or are there some exceptions?


texts: Photodetector and low noise amplifier acting as low pass filter

texts:
I need some basic advice for impedance matching: I have a photodetector (Det01CFC from Thorlabs, https://www.thorlabs.com/drawings/275cb418cdc2cf1f-A2E46103-D9C0-3581-4553E3D3CA93AD83/DET01CFC-Manual.pdf) that generates a current. For my experiment, I would like to amplify this signal with an amplifier to subsequently read it out with a digital oscilloscope.
The amplifier that I use is the LNA-1440 (https://rfbayinc.com/products_pdf/product_88.pdf) with an input impedance of 50 Ohm. Since the input impedance of the amplifier matches the source impedance of the photodetector, I connected them directly with an SMA-cable.
The problem that I am facing right now is that the signal gets attenuated for frequencies larger than a few MHz, i.e. it seems as if my circuit acts as a low pass filter. Do you have an idea why this could be the case?
Thank you very much for your advice!


texts:
I'm trying to find E Thevenin between points A and B. I found the Thevenin resistance, but I'm having trouble finding the voltage.

Note that there were wires that connected the load resistor, but since it's removed, I moved the nodes all the way to the 110 resistor.

I started out like this: since 165 and 55 are in series, their equivalent resistance is 220 ohms. Therefore, the current in this branch is I = 110V / 220Ω = 0.5A. Is that correct? Obviously the voltage U(AB) is the same as the voltage across the 110 resistor. The 110 resistor is a voltage divider, am I right? So how do I apply the voltage divider formula to find the voltage across the 110 resistor (the one in the middle)?


texts: What is the most efficient way to debug CANbus from a PC?

texts: I have several working and inter-operable boards using CANbus. I've shipped hundreds of products using these boards, with no problems. One of my customers is now saying that his fault log shows regular communication losses, indicating that messages are not being received for several seconds. I need to analyze what's happening on the CAN bus to diagnose this problem. What is the most effective way of doing so? I see many CAN/USB dongles, but it's difficult to tell what's useful and what's not without spending a couple thousand dollars buying every one of them.


texts: MRC Variac+ -- NEED HELP identifying this antique electronic

texts:
I gather, so far, that there is a variac component to this equipment. And that it was manufactured by the MRC Manufacturing Corporation (a Subsidiary of Materials Research Corporation), which once stood in Orangeburg, NY.
Please take a gander through the attached photos and let me know what you think. Any sort of description better than 'MRC Variac+' would be greatly useful/appreciated.


texts: How to convert 12v dc to smooth, as if coming from a battery, 6v dc (EMI – RFI free)

texts: I’m an electronics newbie. I did a very simple project. In order to convert 12v dc to 6v dc I used one of those step down converters. Unfortunately what I’m trying to power is an AM radio. It power on without a problem but is completely unusable because of the EMI - RFI. Take in consideration that I usually run it using its ac power adapter (without any EMI – RFI). My question is: is there is a way to convert 12v dc to (smooth as if coming from a battery) 6v dc? The solution must be able to supply 0.4 amps (6v). Thank you very much.


texts:
I'm trying to solve an issue with my eletric radiator and more specifically either the heating element or control panel (circuit board.)
I've tested the element with a multimeter and it is showing what I believe to be the correct resistance but when I do the continuity test the sound is intermittent (like a really quick morse code.)
Does that sound like a bad element and is there another way to make sure?
Regarding the resistance cals. It is a 1500W/230V element with a resistance of 35.8ohms. I work out it should be about 35.2ohms.  Is it within limits?
The new panel is over £150 and can't be refunded if I buy it which is why I'd like to make sure.


texts: Different Pinout Diagram of Arduino Nano / Pro Mini Boards

texts:
Can Someone clear this confusion...
I have some Arduino pinout diagram, with the same logo "bq.com"...

I just find out, there are two types of pinout in those images...
"MISO" & "MOSI" are altered.

Now I'm confused, and which one I used previously... Which one is correct?
And why there are different pinout images by bq.com?

Full image:

https://i.stack.imgur.com/XE5Aw.png

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

https://i.imgur.com/6tUz8vm.png

https://i.imgur.com/S1GaHcE.png


texts: MCP1702 5v: Can work with 6V input and get 5V

texts:
I'm reading the datasheet of the MCP1702.
At page 4 (http://ww1.microchip.com/downloads/en/DeviceDoc/22008E.pdf) it says

input voltage VIN = VOUT(MAX) + VDROPOUT(MAX) or VIN = 2.7V (whichever is greater)

If I did understand correctly, the VDROPOUT is max 650mV at same page for the 5V out.

So, can it works at 5V/250mA with 5.650 V of Vin?

Thank you very much


texts: Can one someone please guide me with the current flow direction and amount of current (Through Gate) (how shall I calculate it) for a P Channel Mosfet? For example if I connect the Gate to something that can sink a very low amount of current, then what happens?


texts: Eagle PCB: "No Supply for Power Pin ..." error

texts:
I am new to Eagle and trying to wire up a schematic. I have an IC and the first basic task I'm doing is connecting ground pins to a GND symbol. Here is what I tried with the error:

(Note: I'm showing "all" layers on the schematic. I'm a little confused as to what the green circles are.)

I was worried perhaps my net wasn't lined up with the IC's AGND brown line and so maybe that net is not properly connected. But I tried a bunch of times and I can't get it to look any more "connected" than this.

Let me summarize exactly what I am trying to do in case this hints at more errors to come.

The IC chip represents a "Teensy" microcontroller. I got the library from here: http://forum.pjrc.com/threads/935-Eagle-library-with-Teensy-3-0-footprint?p=20178&viewfull=1#post20178

Eventually my goal is to connect pins 19 and 18 to a sensor chip, so the Teensy can read them through I2C. I have the sensor chip schematic as well and I'm essentially trying to "combine" the schematics so I can create a single PCB with both components. Then I want to add a bluetooth module, etc.

The point is I am trying to take existing schematics and combine them with this Teensy chip schematic.


texts: Expected and actual unity gain bandwidth LM324N

texts:
I have an LM324N configured as a unity gain voltage follower. The split rail power supply +/- 4.5V is provided using AA batteries. I am aware that better opamps exist, but this is for study purposes only.

simulate this circuit – Schematic created using CircuitLab

As a lab exercise, I am testing performance of the circuit at various input frequencies whilst maintaining a constant input voltage (2V sine wave). The test circuit is soldered onto prototyping board with short traces.

At low frequencies (e.g. 10kHz), the output signal closely follows the input signal. However, at 60kHz the output signal is distorted (closely resembling a triangular wave form) and has an amplitude approximately 70% of the input signal. At 1MHz, the output has an amplitude of 0.1V.

Reading the datasheet, I understand the LM324N has a Gain Bandwidth Product (GBP) of 1MHz, which suggests to me that I should not expect significant attenuation of the signal at only 60kHz. A GBP of 1MHz suggests an ideal bandwidth of 1MHz at a gain of unity. Is this really achievable and/or have I done something wrong?


texts: Why is small-signal output resistance not dependant on device width

texts:
For a MOSFET in deep triode region, we can approximate it as a resistor with the following:

$$
\frac{1}{{\mu}_n C_{ox}(W/L)(V_{GS} - V_{Th})}
$$

However, in small-signal for a MOSFET in saturation, I know that
\$R_{out} = \frac{1}{\lambda \cdot I_d}\$, where lambda is channel-length modulation factor and that is proportional to inverse of length. So increasing length increases \$R_{out}\$. But why isn't it dependent on width? Surely, if I make the transistor very wide, resistance should drop.


texts:
I am new to verilog . I have instantiated a 4-bit barrel shifter in my top module design. shift_mag is the amount by which i am shifting the input.
module barrelShifter( s,Y,shift_mag );

  input  [3:0] s; //The 4-bit Input line

  output  [3:0] Y; //The 4-bit Output line

  input [1:0]   shift_mag; //The 2-bit shift magnitude selection Input

  wire [3:0]    P,Y; //Two 4-bit intermediate lines

  //the barrel shifter implemented as array of MUX shown in the figure

  mux_2to1 m0 (s[3],  s[1],  shift_mag[1],P[0]);

  mux_2to1 m1 ( s[2], s[0], shift_mag[1],P[1]);

  mux_2to1 m2 (s[1], s[3],  shift_mag[1],P[2]);

  mux_2to1 m3 (s[0], s[2],  shift_mag[1],P[3]);

  mux_2to1 m00 (P[0] , P[1],  shift_mag[0],Y[3]);

  mux_2to1 m11 (P[1]  , P[2],  shift_mag[0],Y[2]);

  mux_2to1 m22 (P[2], P[3],shift_mag[0],Y[1]);

  mux_2to1 m33 (P[3], P[0],  shift_mag[0],Y[0]);

endmodule

It works perfectly. But I had to add one more option to it. Here my shift_mag is 00, 01,10 and 11. In,case I have other magnitudes , for example a negative number at the shift_mag , then i should get output as 0000.
How do I include this ? Thanks in advance
Edit: This is how I had written using case statement. one of the solution to the problem i stated above.
module barrelshifter(S, Y,shift_mag);
input wire [3:0] S;
input wire [1:0] shift_mag;
output reg [3:0] Y;
always @ (*)
case( shift_mag)
2'b00 : Y = S;
2'b01 : Y = {S[0],S[3:1]};
3'b10 : Y= { S[1:0],S[3:2]};
3'b11 : Y = {S[2:0], S[3]};
default : Y = 0000;
endcase
endmodule

It seems to work.


texts: Violating the minimum clock pulse width of a D-type flip flop

texts:
Any D-type flip flop has a specification for a minimum clock pulse width. For example, the 74LVC374 has a typical time of 1.5ns for Vcc=3V.

But what can happen to the flip flop if a shorter pulse is applied to the clock input? Will the flip flop just ignore it and stay at its last state? Or is there a possibility for a meta-stable state in this case, so that the output will neither be low nor high?


texts:
I have a simple question, but cannot find the answer anywhere and the datasheets are not very clear. Each 7-segment display have maximum current per segment. If this current is 40mA, single digit display can draw 40mA * 7segments = 280mA. OK...

Here is the question - if a datasheet of a 4 digit display states maximum current per segment 40mA, does a 4 digit display draw 280mA * 4digits = 1.112A (a lot!) ? Or does the value mean "maximum current per segment of all digits shining simultaneously" ?


texts:
I've trying to determine the voltage gain of this circuit (a small signal model of a MOSFET and a few resistors), but I'm having trouble getting enough equations to substitute.
I see that ro and Rs are a voltage divider, so ...
$$V_{in} = V_1 + (V_{out} + g_m*V_1*r_o)\frac{R_s}{R_s + r_o}$$

$$\longrightarrow V_{out} = \frac{V_{in} - V_1(1 + gm*r_o\frac{R_s}{R_s + r_o})}{\frac{R_s}{R_s + r_o}}$$

But from here, I need V1 in terms of vin or vice versa and i'm not sure how to go about that. I'm also interested if somebody has a more "clever" solution to determine vout/vin.

simulate this circuit – Schematic created using CircuitLab

For the curious, this is how I got to this schematic:

simulate this circuit


texts: What physical tool to use to quickly dump firmware?

texts:
Recently, I managed to take a dump of the firmware and write a modified one using the pins that I marked with red by soldering 4 thin wires to those points. Now, I needed to perform this more than 50 pieces of HC05s. I tried to modify a SOIC-8 programming clip(testing clip), it firstly worked but since I could not hold that in place for minutes, it became a problematic.

What tool would you propose me to achieve this flawlessly? Otherwise, it is really hard to hold it in place and to read/write data without any problem.


texts: Eagle library doesn't show up in search after activation

texts: I am having some problems with adding a component in my schematic. I downloaded it from the official Autodesk homepage but I can't find it in the add list. I activated it and i changed the directory of the library? Any fix or solutions? I could not seem to find any.


texts: How does Ohm disappear in noise/power spectral density unit?

texts:
Power spectral density is commonly expressed in Watts per Hertz (\$W \over Hz\$) or \$V \over \sqrt{Hz}\$. When I try to derive these for a resistor I get confused on the units.
If we define noise power for a resistor as \$V^2 \over R\$, how does the unit for R i.e Ohm disappear in the unit for the noise or power spectral density?
It is derived not as I expect as \$V\over\sqrt{Hz\cdot Ohm}\$ but \$V \over \sqrt{Hz}\$.


texts:
I'm using ATmega1280, and I have a question about this BOD table:

what is exactly the meaning of "Min. Vbot" and "Max. Vbot"?


texts: Changing flash latency from 0 to 1 even with enabled prefetch slows execution on STM32

texts:
I have put all clock configuration to its default state, so an internal oscillator is running at 8 mhz. I have a delay loop using inline assembly as follows:

// Delay a certain number of cycles using glorious inline assembly.
void delay(uint32_t time) {
    asm volatile(
        "mov r4, #3                \n" // Divide time by three since the loop is
        "udiv %[time], %[time], r4 \n" // 3x too slow.
        "loop:                     \n"
        "subs %[time], %[time], #1 \n" // 1 cycle
        "bne loop                  \n" // 1 cycle if not take, 2 if taken.
        : [time] "+l" (time)           // Put rw input variable time in r0..r7.
                                       // Make it rw and as output so we don't clobber
        :                              // Time is both input and output.
        : "r4", "cc"                   // We are clobbering r4 and condition code flags.
    );
}

and a GPIO routine as follows:

// Blink the led with a period of 1 second.
while (1) {
    // Set LED pin.
    GPIOA_BSRR = 1 << LED_PIN;
    delay(second_cycles / 2);

    // Reset LED pin
    GPIOA_BSRR = 1 << (LED_PIN + 16);
    delay(second_cycles / 2);
}

When running without wait states everything is fine and performing as expected. But when I change the wait states for flash from 0 to 1, my loop takes 833 milliseconds instead of 500 milliseconds, or a 66% loss in performance roughly.

When I use GDB to debug, I can see the FLASH_ACR register has the contents of 0b0011 0000 which signify that the prefetch buffer is both enabled and has a status of enabled, with 0 wait states for flash. Plus, the prefetch buffer should be enabled on reset as per the datasheet. When I write to the register by or'ing it with 0b001 I get the expected result of 0b0011 0001 back after reading from it again. This is done doing the following:

// Change the flash wait states to 1.
volatile uint32_t foo1 = FLASH_ACR;
FLASH_ACR = FLASH_ACR | (0b001 << 0);
volatile uint32_t foo2 = FLASH_ACR;

Interestingly enough, enabling or disabling the prefetch buffer with a 1 wait state makes no difference in my loop, which doesn't seem to make sense.

And here is the relevant section of the datasheet

I am using an NUCLEO-F303RE board, which uses an STM32F103RE.


texts: Proper way to measure an AC signal with an oscilloscope

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Is there a correct way to measure an AC source with an oscilloscope?
As shown in the schematic below,

I've got a current transducer that is expected to output an AC current of about +/- 1 mA (approx.), and when this current passes through the 10-ohm load resistance, is expected to measure +/- 10 mV.

The op-amp used as the voltage follower has a very low input bias current (~4 nA).

However, I was unable to observe any output with this setup.
Is there something incorrect with the way the AC signal is measured?


texts: Is it a problem when I keep different LVDS traces really close to each other?


texts:
How does this circuit perform Frequency modulation. I know the LC generates the carrier frequency. How does the transistor act as a varicap to perform FM. Which part of the circuit acts as a varicap and how ?

To people who marked this as duplicate - My question is how is the miller capacitance "effectively" in parallel with the inductor ?


texts: Why do lightning data cables have chips?


texts: C4D capacitively coupled electrode sensing - circuit simplification

texts:
I am trying to make a detector to pick up small changes in capacitance. Basically both electrodes have a common ground and are closely spaced. One is driven by oscillator at 0.1-1MHz and the other one is suppose to pick up the signal (current?) that changes. Both electrodes are attached to a glass capillary that is filled with ionic solution.
This is the circuit (the right part) that is a typical design for converting I to V, amplifying it, rectifing and digitizing (?) it. I am wondering how can I simplify it without loosing the sensitivity and maybe use newer ICs (that have better performance). Also I was thinking to just detect the DC voltage with my voltmeter that can be coupled to PC. If I just lose the last part (ADC) in circuit, would it be unstable? Many thanks people.


texts: How do snap-on induction charging systems not interfere with device functioning

texts:
There's a variety of snap-on wireless charging solutions on the market. For example, this one includes a charging mat and a plastic case that is put onto iPhone.

I suppose the winding is in the middle of the case back and occupies a rather huge area. For comparison, MIFARE Ultralight smart cards are size of a credit card and wires can be seen if the card is lit through with a bright light source - they run right along the card perimeter. This question contains a scan of a stripped card.

Now when the phone is placed onto the mat the charging system air core transformer completes and I suppose the magnetic field is rather strong there. How does that field not induce currents in the phone circuits and not interfere with the phone functioning?

I mean, if the phone was shipped with inductive charging the manufacturer would have to design the phone appropriately from the beginning. Yet the described system is shipped by a third party and clearly it was designed separately.

How do such third party snap-on systems not interfere with the device functioning?


texts: How can I tell if a chip has ESD damage?

texts: I have a several chips (microcontroller, PIC16F1939) some of which have weird behavior (random resets, some pins pulled high some of the time). All of them are running the same software. I suspect that those chips have ESD damage (or some other internal damage). How can I be sure? X-ray? Any other method available?


texts:
I have struggled with this question and read many articles and watched youtube videos but to no avail.

For this circuit the time constant or "Tau" is 80 micro Farads (or$$80*10^-6$$)

My issue lies with questions b and c, as I thought the transient period is infinite, I cannot figure out when it ends . I am using the universal time constant formula $$(Final - Start) * (1-(1/e(^T/t))$$

lower case t being 80 x10 ^ -6. however what is meant to be my value for T ? I imagine this would allow me to solve b and c.

Very sorry to post a question like this however I have been trying to solve it for hours.


texts: Regardless of the brand shown in picture, what makes the physical constitution of these type of batteries so long lasting?

texts:
I recently got enthusiastic about electronics again and asked Mom to bring me an old Voltimeter from home. She tested it by trying to power on and it did before going off shortly after.

This device is about 20 years old, so I got excited. We had no idea what kind of batteries it would need so my parents sent both AA and AAA (yes, they're awesome).

By opening the device I was surprised to find everything seemed in perfect condition including the original batteries in perfect external appearance after so many years. (Alkaline batteries would've leaked all over the place).

(SE's image attachment is not working properly, inserting junk characters, I removed them and used img tags for better use of width space)

I double checked and the device is called "RadioShack 22-178 Auto Range HS Sampling Bargraph Digital Multimeter".

The batteries are labeled as R6R (R6 UM3 Special Heavy Duty). Which are made of Zinc and Carbon according to the internet, the batteries don't say so.
They also say to have been made in Poland, is that irrelevant? Or are the properties of the materials being mined there different?(extra/missing electron in atom configuration type of situation, for example) and there's a green apple logo on them (not sure if relevant or if simply trying to convey environmental safety by the brand).

Searching this SE site for zinc-carbon related content I found that someone tested this type of battery by short-circuiting and found out that it got above touch tolerance hot but didn't explode.

So what is the explanation for these properties and should I use exactly the same type of battery or does the Voltimeter circuitry should keep any type of batteries from being damaged?


texts:
Here's a very basic buck converter circuit. The goal is to convert a 6V battery source into a fixed 3V output.

The efficiency of this converter is about 60%. That's not any good at all and I tried to see if I could come up with a much better model so that the efficiency could be improved by at least 30%. The problem with the above circuit is that when D1 is on it consumes a small amount of power.

To remedy this I noticed that M5 and D1 work exactly 180 degrees out of phase, i.e. when one is on the other is off and vice versa. This can be seen in the following diagram:

This gives me the idea of replacing D1 with an ideal switch element so that when it's on it doesn't waste much power and when it's off it acts like an open circuit. I thought of an NMOS as the replacement for the diode:

Though it should solve the problem of D1's consumption it actually doesn't much. I'm getting strange current readings out of input voltage source, and other MOSFETs. Here's a snapshot of the input voltage current, and gate voltages of M1 and M2.

I'm not sure what's wrong with the above circuit. I don't know if there need to be some delay between the turning on and off of M5 and D1 which I haven't considered in my model. Any help is appreciated.


texts: Do I need a full BMS or just protection circuit?

texts:
I'm planning on building a custom battery powered speaker, and am quite new to rechargeable batteries. My amplifier needs 5V, so I thought I would put 2 18650 batteries in series, and use a step down module to get to 5V.

My question is: Do I need a full BMS, or will just a protection circuit do the job? Will all these components work together? Thanks in advance.


texts: Lithium ion battery protection IC not able to drive MOSFET

texts:
I have integrated the TP4056 charger design into my PCB. The problem is that when I connect the battery at the battery terminals, I am not able to get the voltage at its output pin. The circuit can be seen below.

The circuit is exactly same and I have cross checked with my PCB design twice and thrice, it's the same.

Temporarily to overcome this problem,What i have implemented was, I've connected a momentary 2 pin push button between Batt- and out-. The moment when I press the button, I'm able to read the voltage at the output terminals. Also I'm able to get the voltage at the output terminals.

I've also measured the voltages at the respective ICs as below.

The DW01A which is the battery protection IC, which is sole responsible for driving the MOSFET FS8205a. The voltages of this IC are as below.

The pin1 of DW01A (OD pin) which is responsible for MOSFET gate connection pin for over discharge is at 0 V, when I connected the battery. (This pin voltage needs to be high in order to drive the MOSFET, therefore when I press the momentary push button it is getting a high voltage of 3.8 V).

The pin 2 of DW01A (OC pin) which is responsible for MOSFET gate connection pin for over charge control is at 3.8 V.

And the VCC is at 3.8V, and the gnd is also properly connected.

I am unable to know why the OD pin is at 0V.

But when I measured the same test case with the board i bought at eBay,it was working  perfectly fine.

The OD pin voltage is at 3.8 V and the OC Pin voltage is also at 3.8 V.

And I compared the circuit diagram of eBay bought module with mine pin to pin, it's connection, and it is exactly was same as the bought module.

This is the module I bought from eBay.

Hope, I've explained the problem well and there isn't any confusion,and excuse me, if any for my grammar mistakes.

Thanks.


texts: Why stepper motor is slow with A4988 driver?

texts:
I'm using NEMA17 17HS13-0404S1 stepper motors with Arduino CNC Shield & A4988 drivers but I think they're much slower than they should be. Hard to explain how slow they are but compared to Ender 3 Pro 3d printer, they move slow. And also I checked some other step motors from Youtube, seems slow compared to them too.

Here you can find the data of my stepper motor: https://www.omc-stepperonline.com/nema-17-bipolar-1-8deg-26ncm-36-8oz-in-0-4a-12v-42x42x34mm-4-wires.html

I set A4988 Vref to 0.30V (calculated is 0.32 but for 10% margin recommendation, I set it to 0.30) and I'm using 1/16 microstepping.

As power supply, I use 24V, 4.5A power supply and connected it to CNC shield directly (which powers A4988s)

What might be wrong about my stepper motors?


texts: "Interpolation" oscillator working principle

texts:
I was reading Soviet amateur electronics magazines and stumbled upon an interesting oscillator.

It uses two high-frequency crystals (27.14 and 26.67 MHz) to to get a low-frequency output (465 kHz).

I'd like to know how it works and its possible drawbacks.

I presume, there's some kind of mixing action going on but I want to know for sure. The article only mentions that this circuit uses "interpolation method" but that doesn't tell me much. I think I've already seen something similar to this in English literature but I can't remember neither source nor the keywords for searching.


texts: Are all pixels addressed simultaneously in one frame?

texts:
In computer screens, is every pixel turned on during one frame?
How can you address millions of pixels at the same time?
Or is it like in CRT where it is scanned left to right, top to bottom?


texts:
Any CPU has address pins which form it's physical address space.
Some peripherals, like ram or flash can be classified as one big data register which is mapped directly to CPU address space. On the other hand, same peripherals can be connected to system via bus device, and becomes accesible using bus registers by special protocol(e.g SDC/MMC flash via SPI).
Am I right, that in the second case, spi becomes level 2 bus also becoming a peripheral itself(from CPU's point of view)?
What are proc and cons of first and second way of connecting peripherals?
Is it possible to map e.g SPI flash memory to address space, to avoid manual interaction with SPI bus every time? As I know, PCI bus allows to do something like that.


texts: My professor is designing a processor based on OpenRisc. He has told me to set up a JTAG Debug environment in his processor. Now, he gave me some documents which contain TAP controller, Advanced Debug Interface, AXI module and a CPU core interconnected to each other. I did my research on the internet. I learnt that TAP controller is usually on a chip which gets interfaced to TDI and TDO pins of the processor. Could someone explain me what is the internal debug unit in the processor?


texts: How correct is my understanding of basic electricity?

texts:
I have a very basic way of understanding things. Sometimes I over-complicate and sometimes i make it way too simple so I am hoping someone can help me judge my understanding of basic electricity. I am in school to be an Aircraft Mechanic and am working part time at an aircraft repair station where I do some Avionics installations.

In school I have learned that

Ohms = resistance (opposition of current to flow is how I understand this )
Watts = Electrical Power ( What is powering the system )
Voltage = Electrical Pressure ( In my head this is what controls the rate that current flows through the system attempting to return to ground )
Amperes = Current (This is the flow of electricity through the system but I am a little fuzzy on this compared to voltage because to me they seem like the same thing.


texts:
I am trying to run a program on PIC18F4520 using PicKit3 & MPLAB IDE. But I am getting an error:
PK3Err0040: The target device is not ready for debugging.
Please check your configuration bit settings and program
the device before proceeding.

Whereas when I try to run one of the old program, its running. My new program code which is not running is:

#pragma config OSC = HS,FCMEN = OFF,IESO = OFF              // CONFIG1H
#pragma config PWRT = OFF, BOREN = SBORDIS, BORV = 0                       // CONFIG2L
#pragma config WDT= OFF, WDTPS = 32768                                    // CONFIG2H
#pragma config MCLRE = OFF, LPT1OSC = OFF, PBADEN = ON, CCP2MX = PORTC       //CONFIG3H
#pragma config STVREN = ON, LVP = OFF, XINST = OFF                // CONFIG4L
#pragma config CP0 = OFF, CP1 = OFF, CP2 = OFF, CP3 = OFF                   // CONFIG5L
#pragma config CPB = OFF, CPD = OFF                                         // CONFIG5H
#pragma config WRT0 = OFF, WRT1 = OFF, WRT2 = OFF, WRT3 = OFF                // CONFIG6L
#pragma config WRTB = OFF, WRTC = OFF, WRTD = OFF                            // CONFIG6H
#pragma config EBTR0 = OFF, EBTR1 = OFF, EBTR2 = OFF, EBTR3 = OFF           // CONFIG7L
#pragma config EBTRB = ON                                                  // CONFIG7H

#include "p18f4520.h"
#include "delays.h"

void main(void)
{
TRISA=0b11111111;
TRISB=0b11111111;
TRISC=0b11111111;
TRISD=0b00000000;
TRISE=0x11111111;

while(1)
    {
     Delay10KTCYx(200);
     LATDbits.LATD3=1 ;
     LATDbits.LATD2=1 ;
     LATDbits.LATD1=1 ;
    }

 }

Please let me know where the issue is? is it something to do with bootloader?


texts:
I have set up a slave timer that starts counting when the master timer is enabled.

I want to know if the slave starts counting when the master timer receives a valid edge (my configuration is count on the rising edge), or does the slave counter start counting as soon as the master is enabled and the slave receives a valid edge (clocked much faster than master)?

The picture below should help illustrate, I want to know if A) or B) is true. The slave also counts on rising edges.

Technical details: I am using an STM32F072RB, the master timer is clocked externally from a comparator, the master is set up to trigger on Enable, and the slave timer is configured in Trigger mode.

AN4013 snippets:

If scenario B) is true (as I suspect), how can I achieve scenario A)?


texts: calculation of torque constant based on bldc datasheet, getting different torque constants

texts:
I'm trying to get the torque constant of a bldc.
Based on this:
how to read datasheet
I just divide the torque at any given point with the current.
I tried out that method with different values and I get different constants. What do I do wrong? How can I calculate the constant if this method is wrong?
datasheet


texts: Microcontroller sending garbage to Raspberry

texts:
I'm trying to send two commands to my raspberry over serial. I have the following code:

#include <avr/io.h>
#include <util/delay.h>

#define F_CPU 8000000UL
#define BAUD  9600

int main( void )
{
    // BAUD RATE (bits per second)
    UBRR0 = ( ( F_CPU / 8 / BAUD ) - 1 ); // 01100111

    // CONFIGURATION REGISTERS
    UCSR0B = 0b00001000; // enable transmitter (TXEN0)
    UCSR0C = 0b00000110; // set 8-bit data frame size

    char buf[2][222] =
            {
                { "AT" },
                { "AT+CWSAP=\"AVRAP\",\"abcd\",11,0" }
            };

    int i = 0;
    int x = 0;

    while( 1 )
    {

        if( x == sizeof( buf ) )
        {
            break;
        }

        if( i<strlen( buf[ x ] ) )
        {
            UDR0 = buf[x][i];
            i++;
        }
        else
        {
            UDR0 = 13;
            UDR0 = 10;
            x++;
            i = 0;

            _delay_ms( 10000 );
        }

        _delay_ms( 50 );
    }

    return 0;
}

And I'm using the following makefile:

CC=/usr/bin/avr-gcc
MEGA=328p
CFLAGS=-g -Os -Wall -mcall-prologues -mmcu=atmega$(MEGA)
OBJ2HEX=/usr/bin/avr-objcopy
PROG=/usr/bin/avrdude
TARGET=serial

program : $(TARGET).hex
        $(PROG) -c avrispv2 -p m$(MEGA) -P /dev/ttyACM0 -e -U lfuse:w:0xe2:m -U hfuse:w:0xd9:m
        $(PROG) -c avrispv2 -p m$(MEGA) -P /dev/ttyACM0 -U flash:w:$(TARGET).hex

%.obj : %.o
        $(CC) $(CFLAGS) $< -o $@

%.hex : %.obj
        $(OBJ2HEX) -R .eeprom -O ihex $< $@

clean :
        rm -f *.hex *.obj *.o

Note that I'm setting the fuses to use internal clock, so it should run at 8Mhz:

-U lfuse:w:0x62:m

The CPU speed is defined as 8Mhz the BAUD rate is set to 9600, but when I run the following command on my raspberry, all I see is junk:

picocom /dev/ttyAMA0 -b 9600

picocom v1.7

port is        : /dev/ttyAMA0
flowcontrol    : none
baudrate is    : 9600
parity is      : none
databits are   : 8
escape is      : C-a
local echo is  : no
noinit is      : no
noreset is     : no
nolock is      : no
send_cmd is    : sz -vv
receive_cmd is : rz -vv
imap is        :
omap is        :
emap is        : crcrlf,delbs,

Terminal ready
�`�怘��`枆�~������▒�x�x�x�x�x�x�▒��▒�x�x�x�▒������怘�

I don't want to run the micro-controller with external oscillator, can I still use the serial communication at slow rates without using it?


texts:
PSRR is inversely proportional to output impedance of LDO.

But Iout_max of LDO is proportional to width of output mosfet (M20) , Rds of M20 is inversely proportional to width of M20.

Given that output impedance is a parallel impedance configuration between Rds of M20 and (R1+R2), so Iout_max is proportional to output impedance of LDO.

If I need Iout_max = 3A, then my PSRR result looks very very bad. Any advice on this LDO circuitry ?


texts:
I'm putting together an ALU, that I want to synthesize on an FPGA. The carry-look-ahead adder is the one many choose to use as opposed to the ripple-carry adder. However, a thought crossed my mind. The ripple-carry adders I have put together before simply has a series of one bit full-adders connected to each other. My though is, what if I were to design a 4-bit full-adder? I'm not talking about an an adder made up of four one bit full-adders. I'm talking about a single components with 9 inputs (x3,x2,x1,x0,y3,y2,y1,y0,cin). I'm aware this would have 512 possible states (2^(9 inputs)).

What I'm wondering is:

There is obviously going to be a massive number of gates used, is it worth it?
If I were implementing all my components using NAND gates with a certain delay or all of this, how much of an improvement in speed would a see in a 32-bit using a.) 4-bit full adders b.) CLA adder c.) 1-bit full adders
Is there some other implementation of an adder I'm not aware of.
Although an adder is a very menial part of an ALU, what do most digital designers actual go for? Or do they simply use assign Sum = X+Y+cin;


texts:
I am loaned a prototype of an industrial device (running some Linux with an Android flavor). Each time I turn it off, it loses time, and I need to connect it to some Ethernet network then login by SSH to adjust it. The thing is going on tour for a demo (we make the application,) and our salesman hates it.
Sneaking in, I see this. To me it looks like a 3V battery holder without battery, perhaps because there is apparently not enough clearance around to insert one. I could fix this with wires and hot-melt, but I need to be sure.
Can someone confirm/infirm the intended use of this component?
Note: I would make sure the PCB is not attempting to charge the battery before, and after connecting one. Last thing I want is an explosion inside the thing!


texts: Reading/Writing An SRAM Chip with an Arduino

texts:
The Background
I want to be able to program an Atmel AT28C256 EEPROM via an Arduino Uno. I was having no luck in being able to write/read from it, so have fallen back to using an SRAM chip to simplify things (the EEPROM may be in write protect mode for instance).
From the Arduino I'm driving 3 SN74HC95N shift registers which are hooked up in series giving me the ability to write out 16 bit addresses and 8bits of data. So far so good, this is working well and I've verified as much with a logic analyser.
The Problem
However, attempting to read/write to SRAM is failing to ever give me anything on the read. The datasheet for the chip is here,  and it seems to be a pretty simple (to use) affair that works with a relatively broad range of voltages.
According to my multimeter there's about 4.5V between VCC and GND, and I've got a 100uF cap to help smooth things out. This is all built out on a bread board and the schematic is what (I hope) you'd expect, I'm simply hooking up the address (though the top 4 address lines are grounded as my EEPROM has fewer pins than the SRAM) & data lines and then driving the other inputs from the Arduino.
The code is attempting to write 8 bytes, with the values 1-8 to address 0-7. The output from the logic analyser is below (only the first two data lines are shown but they should still show output in the read phase), with write on the left and read towards the right.
The two shift registers for address are always output enabled, the data one is disabled for read operations to prevent contention.

Send Help!
As far as I can work out I'm sending the correct signals, and the timing of the pulses appears to be correct as well (minimum of 50ns on CE and WE and mine are 100us). I'd expect to see two output pulses in the area highlighted above, but clearly I'm missing something. Am I doing something obviously wrong with the control inputs here or is this more likely down to my very amateur electronics skills? I can include code but am hoping the output speaks for itself.


texts: Is antenna length for a baseband signal infinity?

texts:
I am studying RF communications and learned that antenna length is proportional to a wavelength of a signal. And many literature say that a high frequency is preferred in wireless communication because a length of antennas can be short, hence, a size of a device can be small.

From here I can deduce a reason that a baseband signal can't be sent through the air. The reason is that, a length of antennas for baseband signals will be infinity, but in a real world, infinity length of antennas is impossible. Hence, sending a baseband signal through the air is impossible.

However, as I am a learner, I can't tell the above statement is valid.


texts: Using CAN bus tranceivers with custom data link layer

texts:
We needed a noise immune, low cost, multidrop, multi master (realtime and distributed) protocol and there is only CAN bus seems to meet with these requirements.

Since there are no can controllers (data link layer hardware) for very low cost MCU's (such as STM32F0) and no easy-to-use API we could find to get started we can not consider CAN bus as a default communication stack of our projects.

So I think I can implement a really tiny layer that will allow implementing any protocol (like Modbus) over UART over CAN physical layer while taking advantage of data collision detection by using 1 starting byte as a bait.

Additionally, I suppose any I2C or 1-Wire hardware can directly use a CAN transmitter for its bus protocol with a simple diode-resistor hack, similar to 1-wire <-> uart diode-resistor hack.

I suspect I'm missing something since this approach is both bringing many advantages with a relatively small effort although there is no implementation I could find for this purpose.

Are there any hidden consequences on this survey?

Edit

1-Wire (with UART hack) is not working over MCP2551 CAN transceiver, since the transceiver starts feeding itself with zero (dominant) at the end point (the 1-Wire side) which prevents any device from writing "1" on the bus till the transceiver's "permanent TXD detection" function takes over the control. So, it's useless from the point of view of "simple 1-wire range extender". Which means a CAN bus transceiver's RXD/TXD pins can not be converted to an open drain line with a simple 1-wire/uart converter hack, so it will not work either with an I2C bus.

Edit-2

Using 1 byte as a bait is not performant since we have to use only 1 bit as zero, which means we have to use 100 bit just for addressing if we plan to connect 100 device on the same bus because although we could detect someone else is talking at the same time but we can not detect the priority (eg. if node#0b101 and node#0b011 talks at the same time, we will read 0b001 which is just the same response when node#0b011 and node#0b001 talks. So node#011 will never know if it has the priority or not.) So this is impossible if we don't use a bit banging technique and read the RX port bit by bit. Which makes no sense because it's reinventing CAN bus as mentioned.


texts: Diode PN Junction depletion region under bias

texts:
I understood the formation of depletion region in a PN junction with no external bias applied.Immobile ions caused due to diffusion of holes and electrons causes electric field and hence the depletion region. Electric field pulls the majority carries back which is the drift current and the PN junction reaches equilibrium.

My question is when external bias is applied,PN junction is forward biased,why doesn't more immobile ions are formed as holes from P side will move towards the N side leaving an immobile negative ion and electron will move towards the P side leaving behind the immobile positive ion,which can cause the depletion width to increase until it balances the external electric field applied due to bias.More immobile ions will be created in forward bias PN junction and hence more the depletion region?


texts: Bias Tee design for 150V AC and 150 DC at 40 - 50kHz

texts:
my question seems to concern a really easy device. But since I am new to this field of the magical electrons I am very eager to be careful and thankful for any help.

My task is to power an ultrasonic senscomp 600 transducer with 150V DC and an added 150V AC at 40 and 50kHz.
As stated on wiki I only have to dimension an inductor and a capacity, to fit following restriction:

\begin{align}
X_C &= \frac{1}{\omega C} = \frac{1}{2\pi f C} \ll Z_0,\\
X_L &= \omega L = 2 \pi f L \gg Z_0,\\
\end{align}

I have troubles with following questions:

As I understand, you can use a a bias tee to add an ac signal to a dc signal
but also use the circuit to subtract the AC from the DC+AC signal. Is this correct?
How do I choose a correct Z0? The ultrasonic senscomp 600 transducer does not list any impedance values of the transducer.
Is there any possibility to protect my sources and the driven transducer from wrong doing? I was thinking of diodes, to protect the costly sources.

It is hard to imagine, that i only need besides the BNC connectors two more parts to accomplish this.

Some friend suggested to connect the DC and AC source in series, but i don't feel good about this idea.

Thanks a lot - I hope this question fits your requirements.