texts: Eliminate 2.4GHz (Wifi) signal on power lines

texts:
We a designing a small pcb where a temperature sensor is placed close to a add-on wifi module.

The sensor has four traces connected to it power and i2c (3.3V, gnd, SDA, SCL).

The sensor needs to have some distance from other components (MCU,PSU, ect.) due to heat transfer and the pcb power planes are not routed below the sensor.

It is therefore nessacery the use relative long traces from the MCU and PSU to the sensor (about 30mm).

To minimize the 2.4GHz signal coupling onto the power traces going to the sensor, I have added four capacitors close to the sensor (22pF, 100pF, 1nF, 100nF).
I was thinking about adding a small chip inductor, to make the filter even better.

But is this the way to go?

Or are there more efficient ways of eliminating the 2.4GHz signal?


texts: My NE555 circuit triggers falsely when connected to the mains using a 5V adapter

texts:
I have designed a laser security system using an NE555 in monostable mode with a potentiometer to adjust the pulse length. Another NE555 (U2) ciruit is used for delaying power on the monostable circuit so that the laser reaches the LDR first and the circuit doesn't trigger at start. Both are turned on using a double pole switch. There is a relay so that when the 5V adapter is delivering power the circuit uses that not the output from the power bank circuit (which is ~3V when charging.) The power bank has one IC which does not have a label.
The problem is that the circuit works fine when powered using the battery, but when I switch to power from the adapter it triggers after the delay of the U2 in the schematic.
I have tried a few different 5V adapters. One seems to work but after a while the circuit gets triggered.
What can I do to prevent this?
I am new to hardware stuff so my schematic is not something I am proud of.


texts: Can someone give me a basic parts list of required items for .net micro framework development?

texts:
assuming I have already purchased a .net mf board such as a tahoe II, what other items are required?

Obviously sensors will vary on the projects I'm doing, but what stuff will I need for every project?

Edit: Okay so maybe I got excited and didn't provide enough detail. Assuming I have a board such as the Tahoe 2 and a computer and a cable to hook it up and copy programs across. What other items do I need (examples circuit boards, transistors, soldering iron, etc) what are the required items that each project is likely to need.

Update:
Basic Hardware Parts list
•Leds
•Resistors
•Caps
•Transistors
•Solderless breadboard
•Solid core wire
•Crocodile clamps
•External power supply (5V for Meridan boards)
•Multimeter
•Some sensors
•Network Cable

GPIO, I2C,SPI and UART all supported.

Software
Visual Studio 2010 (express or a retail edition)


texts: Sharing power between components in a Arduino circut

texts:
I am trying to power both an ultrasound sensor (HC-05) and an infrared sensor (FC-51) from Arduino's 5V pin, connected in parallel. The circuit is very primitive. When connected separately, both components work properly. But when I connect them both, the HC-05 doesn't give the correct distance reading (pulseIn returns 0).

Here's the schematic (FC-51 looks different, but the pins are the same):

As I said, if I remove the FC-51 from the circuit, HC-05 immediately starts working as it should.

I tested the voltage in each component, and it is correct (close to 5V). I also measured the total current draw of the whole circuit, and it is 36 mA, well below the limits for Vcc and GND pins.

I tried powering the FC-05 from another power source - in that case, HC-05 works. I also tried powering FC-51 from another I/O pin (HIGH) to GND, I/O (HIGH) pin to I/O pin (LOW), and Vcc to I/O pin (LOW), but in every case, the HC-05 doesn't work.

At this point, I'm out of ideas as to why this setup isn't working. Does anyone have any suggestions?

EDIT: I made another experiment, powering Arduino from a power bank, rather than USB cable from my PC. With a power bank, HC-05 works perfectly... But now FC-51 does not! The standby light turns on, but the proximity light does not when I wave my hand in front of it.


texts: What are the main considerations for a battery operated project

texts:
I just wanted to know what are the major considerations to be taken into account while designing a battery operated project.

What are the major optimizations to be done in order to improve battery life.
What kind of battery to be used,what type of voltage regulators,what are the best way to charge the battery(if using a li-ion battery)and what protection circuitry to be used and maybe a few tips and tricks here and there for better efficiency.

Sorry if this is a stupid question,I just wanted to know.


texts:
What is meant by "draw a 2:1 CMOS inverter with lambda design rules?"
Do I have to take double scale while drawing PMos in the layout diagram?


texts:
I know that polar form has two parts. Amplitude and angle but
What is difference between polar form and phasor form of complex numbers?  Or phasor form just includes amplitude form of a complex number?


texts:
Without knowing how I should approach to STM32 development board, I purchased Olimex STM32-H407 which would work with OpenOCD.  and I purchased ST-LINK/V2 hoping that any JTAG cable would work.  My PC does not seems to understand ST-LINK + Olimex STM32-H407.  Are they useless combination?

Should I always go discovery board + ST-LINK? otherwise STM32-H407 + ARM-USB-TINY-H?

Thanks.


texts:
I am trying to implement a simple LT Spice circuit; it takes extremely long a 50ms simulation isn't settling even at 5 seconds. Tried adjusting the internal capacitances of the component, the AUX has a demand of 36V, which seems to be the issue. Each part of the circuit is working seamlessly on its own, but when I am merging them, it seems to be an issue.
PS I am new to LT Spice. Any help is appreciated.


texts: Correct solar panels to pick for drone-mod

texts:
After this, I think I will take a course on electrical engineering (fuzzy from school days).

I'm trying to add some flexible panels (they were <14g a panel)) to my drone (HS120D), to possibly give my drone a flying time boost by charging the battery while it's being flown in the sun.
I'm aware that doing this will void my warranty, not worried about that. The panels will be connected to the battery with diodes in between (to avoid draining bat when panels are in shade/lowlight for some time).

The battery is 3.7V, 1200mAh and weighs idk (like 1/3 pack of playing cards). I am seriously considering upgrading the battery to a 3.7v 5000mAh cell (4x current capacity) too. But the thing is 76g.
The drone weights 220g (7.8oz) w/o battery or blade guards (all 4 might weigh an ounce). I will reduce the weight by removing excess plastic frame, at least 30g (probably more). Drone normally gets 18min flight time/charge (no recording, ~ 15m flight+recording). Wires, diodes, removable frame (paperclips) might weigh 40g combined.
So I'm increasing the weight by At least 80g.

Finally, the blades will pass over ~ 5.5 more square inches of panel, distance of 1.5cm below (the closeness will reduce lift, I know).

Tl;dr

Which voltage panels should I use for:
A 3.7v 1200mAh battery and
A 3.7v 5000mAh battery?


texts: Phase voltage from unbalancd line voltages symmetrical components

texts:
I'm trying to calculate the phase voltage of a given unbalanced sources star connected from the given line voltages. I'm trying to employ symmetrical component synthesis to find a solution.

I know the zero sequence component of line voltage is always zero.

To find the phase voltages with symmetrical components, I've to find all the three components, the positive and negative sequence component of the phase voltages are easy to find. But how can I find the zero sequence component of the phase voltage, from the given line data.

The given data are :

Eab = 2760 V

Ebc = 2300 angle(-138.6) V

Eca = 1840 angle(124.2) V

I'm trying to find Ean, Ebn, Ecn . I may be assumed that the neutral point is grounded.


texts: Instantiating module in condiotional block verilog

texts:
Considering a module cannot be instantiated inside if block, how are we supposed to instantiate the module outside the if-else block, keeping in mind that the inputs given to module in if and else blocks are different?

Problem:

if(sel==0)
  moduleex s1(inp1,out);
else
  moduleex s2(inp2,out);

What is the legal way to write this logic in proper Verilog syntax?


texts: Question about comparator and 555 timer circuit

texts:
I'm designing my first circuit for a university project.

This circuit will check the voltage of two sensors. If both are over a reference voltage and persist as such for more than one second, a relay will switch on. Until I switch off the entire circuit by pushing the master switch, the relay must be closed.

I'll using op-amp LM393 for the two comparators, NE555 with the RC circuit (charging of capacitor lasts one second), the AND gate to verify both the conditions of the comparators, and the OR gate to maintain the power to the NE555 until I switch the master switch.

In your opinion will it work?

The power supply of the op-amp and the gates is taken from +VBAT.


texts: Change output voltage range from potentiometer

texts:
I am using a 10K potentiometer to produce an adjustable voltage of 0..3.3 V from an input voltage of Vin = 3.3 V.
How can I change the circuit so my adjustable voltage range is 1..2 V ?


texts: My LED lamp is blinking. Could the power supply be the issue?

texts:
I have a lamp that I received without power supply. It is pretty simple, just three LEDs and a switch. The device wants a 13V, 700ma power supply. I've had some 12V supplies with 1.25A that worked for a little bit, but did get the lamp/heatsink for the LEDs really hot and started blinking.

Now it blinks as soon as I turn it on. I'm trying to understand what is going on here.

Did the LEDs basically run the power supply too hard and break it? Is there a better explanation of what may be going on here?

Is the only real solution to the keep it from happening to provide the proper 13V or could I add some resistance with the result of slightly dimming it or something else?

Am I correct that having more Amperage isn't a big deal in this scenario if I can find that 13V?

What should I expect if I plugged the 12V rail from a modified PC power supply into it?

If all this is overly simply stuff for this community, please point me in the direction of where these questions might be appropriate.


texts: 5v DC +ve connected to 24v negative is this safe?

texts:
Sorry for this really weird question, but I'm not very knowledgable on electronics.
I have a circuit board that measures rotational speed.
It needs 5v input , and a gnd , and then has a signal output giving 1 pulse per revolution.

My problem is that this signal is input into a controller card which is fed by 24 v

The signal is configured active low in the control card software, and this signal works if I connect it momentarily to the control card 24v -ve.

However when I connect the signal wire from my rotation card to the input pin, it isn't recognised .

I think I should connect the rotation card negative to the control card negative, but I'm afraid to as I don't want to blow something up.

When I tested this connection without actually plugging into the cards, I find that there is a 7.5v reading between the 5v+ and the 24v -ve.
Hence my hesitation as I think the 7.5v will blow up my rotation card.

What the correct way to do this, so that a card with 5v source voltage can pass an active low signal to a card with 24v source voltage

Sorry if this question is asked in an unclear or unprofessional way using the wrong terms.
Please consider that I'm a complete novice with electronics.

I've read a few posts about common ground etc but it's not really making any sense to me right now

Will it be safe to do what I think is right and connect the rotation card GND to the controller card negative so that my input signal can be seen by the controller card software as active low.


texts:
This may be a little hard to understand.

I have little knowledge in electronics, but I had an idea about optical fiber for data transfer, as far as I understand, ports/inputs/terminals/pins must be connected and sorted to the right terminals, otherwise data won't be able to be sent through the data pairs(for example RJ45 & CAT cables)

simulate this circuit – Schematic created using CircuitLab

Sorting and connecting for a few data pairs (such as CAT cable) isn't really a problem, but in the situation like the internet, where a dramatic increase in wires/fibers are used (i assume), sorting and connecting the tiny cables by hand could take a lot of time, for each repeater/amplifier

My question is:

Will it work if fibers are randomly connected to ports in the terminals without physical sorting?

where they instead are later sorted electronically through test signals, (1,2,3,4 etc) for each fiber?

Does this already happen, if not, why not?

Note:
Sorry for my bad terminology, I hope you understand!


texts: Battery backed up power supply using LDO

texts:
I was looking for a battery(12V, 11.2Ah lead acid) backed up power supply solution for my ESP microcontroller(3.3V) along with few relays(3V) and came across some reference design in the following LDO data-sheet which seems to be simple and effective. It seems to charge the battery and provide power for the ESP when there is input supply and switch to battery during an outage.

Data-sheet link - https://in.element14.com/on-semiconductor/ncp1117st33t3g/ic-linear-voltage-regulator/dp/1652366 (Refer data-sheet Figure 31)

Below is the modified version to provide 3.3V output. I have few queries as below.

What must be the values or specification of those diodes D4 and D5
Will a 10 Ohm resistor that is in series with the ground pin of the upper LDO ensures that the lower LDO is off until the input source is removed (approx 0.1V difference).
What must be value for the resistor R1?
Is this a stable solution that can be used in production systems ?

simulate this circuit – Schematic created using CircuitLab

Note - The power supply is rated 15V,2A and battery is 12V, 11.2Ah. The ESP along with the relays would only take a peak current of 850mA. A cutoff for charging would be added for battery safety. I also understand that a buck converter would be much efficient, however I was looking for a solution with least and low-cost components and prefer cleaner output without adding too many capacitors.


texts: Accuracy problem of a DDS at very low frequencies

texts:
First time in my life I'm using this DDS chip (AD9850) to create sine wave at a desired freq, where I upload the lookup table code and the desired freq. command via a with micro-controller. So my knowledge at the moment very limited.

The thing seems fine so far but the problem is at very low frequencies. At 1Hz and even 0.5Hz seems fine. But I also need down to 0.1Hz.

Here is the output of DDS when I send the number 0.1 to the DDS via the micro controller:

In my code I send the command from PC to micro as string and convert it to double.
But for simplicity and to verify I use this code, and for 0.1Hz I set sendFrequency(0.1) in the loop.

But as you see the period is around 11.5 sec instead of 10 sec for 0.1Hz command.

I hope I could explain the issue well. Is there a way to calibrate or fine-tune this so that I would have more accurate result? Or I should live with the accuracy? Btw where in the data sheet one can refer to such relative uncertainty?


texts: How can I fix this Firewire 800 header by soldering?

texts:
Unfortunately I found the headers on my computer's belkin 3-port Firewire 800 all tilted back somehow, and they snapped off when I tilted them forward to where they should be. As a quick fix, I have a smaller Firewire 800 card, but, it is not fitting for several reasons.

As a result, I may be forced to cannibalize the headers from the smaller Firewire 800 card and solder them onto the broken card.  I need a fast fix because this is an important computer.

Generally as you can see below there are three headers on the broken card, and the central one looks quite damaged.

What are the steps that I should go through in thinking about whether I want to do this or not, and what are the tools I should have available?  I have solder and flux, decent soldering iron, microscope.  It looks like I could go for the left and right header for replacement.  What do you think?  Does it look possible, and where should I be most careful?

If there is a short video guide on soldering headers that is your very favorite (using the best technique), please feel free to include.


texts:
Can FPGAs be emulated on general purpose computers? As per Church-Turing thesis all Turing machines can be emulated on the universal Turing machine. So if the FPGA can emulate processors, can the processors emulate FPGAs?
I am asking this question so I could know if instead of using FPGAs for Digital ASIC emulation, can we use a computer instead?
For this question, I am considering only the digital applications of FPGAs.


texts: Do all non self starting counters have lock out problem?

texts: I understand that a self starting counter is one which could start counting from any state but eventually reaches the required count sequence, meaning if a non self starting counter starts from an unused state it would non enter into the used state. So isn't it same as lock out problem? Can I conclude that a non self starting counter suffers from lock out problem.


texts: STM32L071KZ battery voltage monitoring via ADC

texts:
Sorry for the newbish question. I didn't find here any questions and answers that can help me with this issue so I decided to ask it.

I'm designing my first circuit with STM32L071KZ microcontroller and it powers via VBUS(USB, 5V) as a primary supply and 2xAA alkaline batteries(3V) as secondary supply.

the power supplies are regulated to 3.3V so the microcontroller and the rest of the circuit are powered by regulated voltage and not directly from VBUS or batteries.

I would like to monitor the batteries voltage level and when it drops below the specific threshold(For example, 2.2V) I will indicate it to the user.

I wonder how to wire things up. microcontroller's VDD is 3.3v and it equals to VDDA. If I got it right, when I will sample the voltage of the battery I will get a constant value because the sample is the ratio between the VDD and VDDA.

This is my power circuit block diagram to make things clear:

Thanks alot!


texts: How to control switching of mosfet in PFC boost rectifier using PI controller?

texts: My aim is to reduce THD in the supply current and I wanna use a simple PI controller for that, to make the inductor current more sinusoidal and at the same time keep the output voltage of the converter constant. My current circuit can attain a controlled output but I don't know how to keep the supply current sinusoidal.


texts: C - V characteristics of MOS capacitors for different material

texts:
For C-V curve below for 3 different materials, (Si, InAs, InSb). What material will be corresponding to curve A/B/C?

My understanding is that C is inversely proportional to the dielectric constant in the inversion region. As a result, Si has the smallest dielectric constant and therefore matches with C.
InAs = B InSb = C

Is my understanding correct? Thank you for your help!


texts: Voltage across capacitor in charging RC circuit with constant current source

texts:
simulate this circuit – Schematic created using CircuitLab

I couldn't really figure out how to get the switch that I wanted but this is functionally the same.

Before the switch flips, there's a short and no current flows into the other parts of the circuit. Therefore Vc = 0

In order to solve for Vc I set up the Kirchoff's Current Law

$$ C\frac{dV}{dt} + \frac{V_c}{R} = I_s$$

This is the step I get stuck at. If this were a voltage source then I could use separation of variables and integrate. But I don't know how to integrate this with a current source.


texts: Driving a 6V relay from an 3.3v GIO pin of Raspberry PI3

texts:
I want to drive this 6v relay (RT314F06) from a 3.3v output gate of an GIO pin of a R-PI3.

--edit--

There is already this answer on SO, but it is incomplete in the way that it does not tell which discrete components to use. I my case this is important since I'm too novice to decide which components to choose myself.

--edit--

Given that I have also a 6v power-supply, what component should I use to upshift the 3.3v to 6v?

The relay requires 6V and has an internal resistance of 55 Ohm. So, if I am correct, the driver needs to be capable of driving about 100mA.

Can I use a converter like this? I think it can shift only to 6v and I can't find how much current it can drive.

Thanks for the advice.


texts: Learning about the Interrupt system of the 8085 processor

texts:
I am trying to investigate the RST5.5, RST6.5, and RST7.5 interrupts on the 8085 microprocessor.

I want to find information about the to the type of interrupting signal used and the built in hardwired priority scheme,but finding resources explained in a plain and simple way is next to impossible...even the Intel documents are very hard to understand!!


texts:
I'm just trying to visualize how the current flows in the following circuit. It is a follow-on question from here. The circuit is a small-signal model for a common-source MOSFET with source degeneration. In particular it is analysing the output resistance using voltage source Vx and measuring Ix. However, that is irrelevant to this question.

I have a few ideas, however I am pretty sure 1 and 2 are just outright wrong.
Explanation 1

In this explanation, I was thinking that the VCCS is generating a current in that branch. That current must come from the node that is connected with Vx and ro. That gmvgs current will be sourced from the two branches depending on the impedance that the current 'sees'. Since Vx is an ideal voltage source, it must have 0 input impedance and hence the gmvgs current must all flow through that. This gives Ix = gmvgs.
Explanation 2
This explanation is  very very flimsy.

In this explanation, I am also thinking about current division but from the point of view of the Ix current. Ix is flowing into the with the ro branch and VCCS branch. I thought that the current should divide according to its resistance. However the input resistance of a VCCS is not defined?
This explanation seems completely wrong and my conclusion for this was that the current-source will pull that current no matter what, so current division isn't possible?
Explanation 3
This explanation seemed the most logical to me.

In this explanation,

gmvgs flows from node X into node S, so it can be thought that a loop is formed with ro, since the VCCS will want gmvgs flowing into it and flowing out.
Now that the VCCS branch is happy, the Ix current must then flow through ro, through Rs and to GND.

If someone could just clarify these doubts in my mind that would great. I just would like to know why some of my explanations (or all) are incorrect and what is the correct way to go about thinking of this circuit, particularly when ideal elements are involved. Is current division still valid, since the series resistance of an ideal voltage source is 0?
Thanks.

In response to comment from Andy Aka:


texts: Im using a fca47n60 mosfet and when I put my voltmeter on  the source and the collector, my voltmeter says that the two pins conduct electricity. What is wrong?


texts: Verilog: Can I omit the length of a register that is initialised to a string?

texts:
In Verilog, one can work with strings as follows:

reg test [12 * 8 - 1:0] = "Hello world!";

Is there a way to tell the compiler to simply have a reg of the appropriate length similar to C?

reg test [] = "Hello world!";


texts: How to wire 12 cameras to trigger simultaneously

texts:
In the documentation of a camera it says:

  "To activate a GPI trigger, momentarily short pin 2 to 1."

But I have 12 cameras and I want to trigger 12 cameras at the same time, how should the circuit be for that? On the pins, there are 3.6 V.

I am really a beginner.

To give more information: this is from the handbook and its a red-one camera.


texts: How do I create a knob like on my amplifier

texts:
On my amp, I have a big round knob, that I can turn forever in both directions, to control volume.
It simply turns up whenever I turn clockwise and down when I turn counter clockwise. There is no limit as to how far I can keep turning it.

How do I create this in my own project?
I have an arduino where I want a knob like this, to control a value in the arduino memory. Simply, turning up, add to value, turning down, subtract from value.

I assume I need some kind of potentiometer, but they do not turn forever, do they?


texts: Select power source with reverse current

texts:
I'm designing a Split keyboard where each half can be connected to USB, or to the other half, or both. If one half is not connected to USB, it receives its power from the other half. 99% of the time these will probably be connected to the same computer, so simply connecting all 5V together only has the effect of connecting the 5V and Ground of two USB ports on the same computer (potentially on different USB hubs/controllers). This doesn't feel very safe, especially since I might connect each half to a different computer while the halves are connected to each other.
Each half is an instance of the same identical circuit, so there is no asymmetry in design possible.

While the USB port will only supply 5V (if plugged in), J2 and J3 can either supply or recieve 5V depending on whether the other side is plugged in to USB.
I investigated using an ideal diode solution, but the problem comes when supplying the power back to the other side:

The LM66100 datasheet is available here. If +5V were connected to EXT_5V, I'm not sure of the effects on IC2 as VOUT is connected to VIN. Perhaps with a resistor it would be okay?
Essentially there are three situations that each half can be in:

This half has USB power: it should use the USB power, and supply USB power to the other side. This half should not accept power from the other side.
This half does not have USB power: it should accept power from the other side
Both halves have USB power: they should run off their own USB power, and the two power supplies should not be connected.

Is this possible over a single shared 5V conductor? I'm open to all suggestions, not just modifications to the ideal diode setup. It would be very inconvenient to use a different connector to the TRRS shown, but if that's what it takes...
The 5V will be used for a 3.3V regulator for the microcontroller, as well as powering WS2812b LEDs. If the LEDs will work off a slightly reduced voltage then solutions involving a diode might be okay.
Thanks in advance for your helpful responses :)


texts:
I want to start this DIY project. According to the video, you need "2S 7.4volt battery and DC jack". What battery is this?
https://www.youtube.com/watch?v=cpdjQ0gheDQ&feature=youtu.be&ab_channel=CreativeChannel


texts: Pulse withstanding capability of standard resistors

texts:
How much pulse power does a standard (i. e. not further specified) resistor withstand?

Consider for example a MOSFET and a 33R resistor that is connected to its gate. If the switching voltage would be 10 V, the resistor sees up to 3 W every time the MOSFET gets switched - but only for a very short time, until the gate (in my case, about 15 nC) is charged.

Do I really need to specify a pulse withstanding resistor? Or is there any way to tell whether a 0402, 0603 or 0805 standard resistor (without further specification) will suffice?


texts: i have successfully implimented below circuit for active cell phone detection but i dont seem to understand the working of this circuit,if someone could explain it would be a great help.Thank you.


texts: names of the marked electronic components in uploaded images

texts: I want to know the names of the marked electronic components. One seems like a capacitor and the other some sort of pcb fuse switch. I want to know their specific name, so that I can search and know more about them. The gray one has "105K63" written on top and the orange one has "40" written on top and "628" written in top right corner.


texts: If I supply more current than needed will my electronics fry

texts:
If I have a stepper motor and driver that require 5V and 240mA and I supply 5V at 3A will my circuitry die?
I have heard the expression that a motor "draws" the current that is needs, but I don't really know if that's true, and if it is true, how's does that even work? It does not seem to be the same for voltage.
I am very beginner with electricity so simpler is preferred thank you all for taking the time to answer I really do appreciate it
Edit: Apparently this is a frequently asked question, view the answer here or go to this page to see one of the largest community discussions on the topic


texts:
i have an output reg called compressed_out.base_size and delta_size are parameters.  if the enable[l] = 0, I need the base_size bits in sub_out to be written to  compressed_out. if enable[l]=1, only delta_size number of bits from sub_out is to be taken to compressed_out. how can we give correct ranges in the body of if else statement to select bits of compressed_out.
my code is not correct, please help me to solve the issue.

wire [base_size - 1:0 ]sub_out[n-2:0];
.
.
for(l=0;l<n-1;l=l+1)
    begin
    if(enable[l]==0)
    compressed_output[(base_size *(l+2)-1)-:base_size] = sub_out[l];

    else
    compressed_output[(base_size - delta_size)*(l+2)-1 -:(base_size - delta_size) ] = sub_out[l][delta_size -1 :0];
    end


texts:
I'm going through Chua's 1971 memristor paper. I am stuck on a part that I believe in pretty crucial. It is

  Observe that the, value of the incremental memristance
  (memductance) at any time to depends upon the time
  integral of the memristor current (voltage) from t = - co
  to t= to. Hence, while the memristor behaves like an ordinary
  resistor at a given instant of time to, its resistance
  (conductance) depends on the complete past history of the
  memristor current (voltage). - Page 511(page 5 of the pdf) top of the right column

http://www.cpmt.org/scv/meetings/chua.pdf

I'm not seeing the integral from any of the equations 1 through 4 that are presented in the paper.

When I read the section in question, this is what comes to mind, but I cannot see the derivation. Am I thinking about this incorrectly?

To expand further on what I have tried

Does anyone see anything glaringly wrong with my math? Is it a physics thing possibly? I'm not seeing how current gets into this at all. I realize memristors is a rather newish topic that not many people are aware of or even care about.


texts: PIC16F676 - Is it possible to add a dimmer circuit to the seven segment displays

texts:
I am attempting to build a PIC16F676 based voltmeter using 3 multiplexed common-anode seven segment displays. Is it possible to add a light activated dimmer to control brightness of the displays through the PIC or control the current externally against the displays them selves? It would result in a bright display in bright conditions and dimmer in dark conditions to not be blindingly bright or distracting. Most standard seven segment displays are not usually that bright but this is a large display using bright leds.

Edit: I am adding the schematic that I'm working off of. Guess I should have added in the beginning. Sorry folks.

Original site:
http://www.circuitvalley.com/2012/02/30-volts-panel-volt-meter-pic.html

In the display, each segment contains 5x leds in parallel. As a result, the BC557's will need to be changed to something larger as 5x parallel leds may draw >100ma. The problem of the leds is that I'm using 01005 SMD leds in a small form factor but I am only finding them in stoopid bright instead of standard bright. :( When I thought of posing this question, I had difficulty figuring how to title it and I'm trying not to draw the question in that direction.


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I have started the design of a high speed digital design multi-gbps interfaces.
I would like to use Altium designer for PCB analysis (signal integrity). But I am wondering if altium uses the IDEAL model of a capacitor for simulation. The impedance/frequency response of typical capacitors is something like the below figure

So the impedance/frequency characteristic is quite different than an IDEAL model (There is a parallel issue with inductors and partly resistors too). My Questions are:

1-Does Altium use ideal models for signal integrity analysis?

2-If the answer to 1 is Yes then why? To what degree results are valid?

3-What is the policy of HyperLynx in this situation?


texts: RF signal generator, spectrum analyzer measurement questions

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I want to test the attenuation characteristics of an RF filter I’ve built into a project, but do not have any experience using RF signal generators or spectrum analyzers.  In all of the videos I have watched on the use of RF signal generators, I have yet to see one where actual probes were used … filters were always tested on a separate pcb with sma connectors built in.  In my case, the DUT has euroblock connectors at the outputs, and I would like to measure the frequency response at the opamp output to simulate RF common-mode input from the output cables using one of these.

I envision performing the measurement as shown below, but am not sure if this will work correctly.

Although drawn separately, the RF signal generator and scalar network analyzer are the same device shown in the link above.

I have the following questions:

1)  The sig-gen has 50 Ohm output, and the built-in scalar analyzer has 50 Ohm input. Do I need to use a buffer circuit terminated in 50 Ohms (and perhaps with a 2x gain) before and after the DUT to avoid cable reflections for an accurate response, or can I just run the signal through the DUT to the analyzer as is?

2)  I have only ever used standard signal generators to 25MHz with mini-grabbers to interface with test circuits.  Is there something like a grabber or some type of probe that is used with RF signal generators for injecting the RF signal into the DUT, if the device does not have an sma connector and does not have 50 ohm termination?

3)  Are there probes commonly available to use with spectrum analyzers that can be used to measure the frequency response of a circuit where no SMA connector is built in, similar to using an oscilloscope?


texts: How to determine point of failure in photodiode circuit

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I have a photodiode circuit which uses a fiberoptic pigtail photodiode as shown in the picture below:

The photodiode is connected to an opamp as in the circuit below:

The supply rails for the opamp are +2V and -38V.

The situation I am having is that sometimes I have no voltage on the output of the opamp. I saturate the photodiode using a laser pointer and typically measure around the -25V region when the circuit is functioning correctly.

If I replace the photodiode, the circuit works as expected. However the "faulty" photodiode I remove, I check using a multimeter in diode mode and measure a 0.57V drop, the same as usual.

Besides measuring the voltage drop using a multimeter, how else can I verify if a photodiode is good or not?
The circuit is assembled by an external manufacturer so there is a possibility for fiber breakages during shipping, how is it possible to determine a break along the fiber?

Edit:

The datasheet for the photodiode: Datasheet


texts: Replace Current controlled Voltage Source Converter with Rectifier Diodes in ELC?

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In this paper an Electronic Load Controller (ELC) for two (2) parallel generators is designed. I wish to omit the second generator and hope for simplification.

Now two questions arose: (while I believe I get the point that this is how the reactive power is controlled while functioning as a normal recitfier for active power control, i.e. frequency control)

Inductance for high power rating are very expensive - why exactly do we find 1-Generator 1-Phase designs where the inductances are omitted? Or rather: Why do we need this inductance for filtering, buffering of reactive power here in the mentioned ELC design? Is it related to the 2-generator configuration? Is it because of the 3 phases? Is it possible to omit or replace their function?
The working principle of the PWM dump loading is that we rectify the power the generators produce and no load currently needs. This task is solved by a Voltage Source Converter (VSC). The question arises if it is possible to go with Rectifier Diodes instead as simplification?

@2. Currently I can't see why not other than that some special power component is being controlled by this VSC or probably because diodes are not suitable for 5..20kW power range?


texts: I am attempting to short 2 different wires, call them A and B when C I'd powered. I am attempting to use a transistor, but when I attatch C to the base and A or B to the emittor, it just powers A/B which isn't what I want, I need A/B to be shorted. Is there a way to configure a transistor to do this? Or might I need a relay of some sort?


texts:
I've been shopping for a voltage regulator that works in a range of .5-1.5 (+/-.5) Volts, but they are not easily found.

I'm wondering if anyone knows whether they even exist, or possibly how to make one.
Thank you,

L.


texts:
I just recently organized all the assortments of components I own and it all currently resides in my garage. I live in Michigan, so our weather goes back and forth on both extremes of temperature and humidity.

Is it advised not to store certain common components outside in cold environments for longevity purposes/etc.?


texts:
A silly question but am little confused as to which one to go with. I would really appreciate if somebody could advise/comment on the schematic. With the best of my knowledge and google i guess my schematic would work. I don't have the parts to test this out but before i do i just need some advise. I have a project where i need to sample the mains voltage into my MUC (an Arduino) so i came up with this schematic of a precision rectifier, attached as CS.

Explanation
Idea here is to detect when the secondary of the Transformer (MOT) is shorted. The LIVE LOAD here is a transformer (MOT) used for Spot welding, when shorted i can a voltage drop from 1.0vac to 0.5vac i just need to send this voltage to the ADC of an Arduino. So here for isolation i used a MOC3052 (https://www.digikey.com/product-detail/en/on-semiconductor/MOC3052SR2M/MOC3052SR2MCT-ND/1847083)optocoupler from fairchild. The LT1078 (https://www.digikey.com/product-det...g-devices/LT1078S8-PBF/LT1078S8-PBF-ND/889633)is a dual opamp precision rectifier from LT. C24 is a decoupling cap and C25 is to smooth the ac signal from LT. Then the second opamp is a buffer.

Working
The the optocoupler would be triggered by the MUC via 220Ω resistor there by shoring the contact from the LIVE_LOAD to the voltage divider and that goes on to send a dc voltage to the MUC. This happens when the MOT is not powered.

When the secondary is shorted, there would be a voltage drop at the primary contacts of the MOT and that would also be seen by the LT1078 and using code, the voltage drop would be sensed by the MUC then the the optocoupler would be disabled and the MOT would be powered for spot welding. Basically an Auto Sense, instead of having to press a button to switch ON the MOT.

Then i noticed this schematic from TI, attached (http://www.ti.com/lit/an/sboa097b/sboa097b.pdf) page 4 Fig3 where a similar approach with less components. My basic requirement is to sense the voltage drop at the primary of the MOT and switch ON the MOT.

Would really appreciate if anybody could advise.


texts:
I'm working on a phase-sensitive-detector that uses an FPGA for signal processing.For an input of a pure sinusoid with known frequency and in the range of 1 Vrms, I need to find the phase of the input in reference to a produced reference signal.
My math is as follows:
$$A*sin(w_0t+\phi) * sin(w_0t) = \frac{A}{2} [cos(\phi)-cos(2w_0t+\phi)]$$
$$A*sin(w_0t+\phi) * cos(w_0t) = \frac{A}{2} [sin(\phi)+sin(2w_0t+\phi)]$$

where my input signal is $$A*sin(w_0t+\phi)$$ I'm going to filter out the larger frequency components and will be left with $$sin(\phi),
 cos(\phi)$$  with which I can determine the phase from there.

Then I realised I need to give a DC offset to the input signal for A-D conversion, because ADC has a range of 0-Va. I got lost there. The new equation looks like$$[V_{off}+A*sin(w_0t+\phi)]*sin(w_0t) = V_{off}* sin(w_0t)+\frac{A}{2} [cos(\phi)-cos(2w_0t+\phi)]$$ Should I then filter out the frequencies w_0 and above? I kinda need reassurance. Is there a better way?


texts: What to do with the Balance and NC pins?

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For a course project, we are to use an LF356 operational amplifier

What does the Balance and NC do? and I do not think I need it for my project(Sallen-kay filter 4-pole). Do I just ground it?


texts: Where do I put digital ground in a dual-rail mixed signal circuit?

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I'm working on a project for school (a discrete dual-slope ADC) that will combine digital and analog circuitry and operate off of a ±15V dual-rail supply. The "analog ground" will be at 0V, as expected. However, I'm not sure where I should ground my digital circuits.

simulate this circuit – Schematic created using CircuitLab

Should I put the digital ground on the same node as the analog ground? Or should it be connected to my -15V supply with VCC regulated to -10V?

Since I'm dealing with "precision" analog circuitry, I want to minimize switching noise.
My Vref regulators are referenced relative to ground, and control +Vref and -Vref via feedback loops (not shown).
The digital output from the analog block will be either open collector or open drain, so I can adjust the output level as needed.

The first option is more intuitive, but will the second offer significantly better performance?
In the digital section, I plan on using a mixture of 74HC and 74AHC chips. Will using the AHC chips at HC speeds introduce more switching noise than using all HC chips?
What degree of decoupling is necessary? Will 100nF caps on each digital chip plus something like 10uF between the supplies and ground be sufficient?


texts: RS485 - Comunication lost during EFT IEC 61000-4-4

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I'm having throubles with communication over RS485 in harsh industrial environment.
We perform test in EMC lab, acording IEC 61000-4-4 = Fast transient (also known as Burst).

We used burst generator and capacitive coupling 1m long around RS485 cables. We used pulses +/- 500V.

Here is our RS485 schematic. It use galvanic isolator TI ISO1412.

I measured with a scope A and B lines on the RS485 connector during Burst testing. I see that there are disturbtions on A and B lines and on A-B math as well. So noise is not suppres that diference reciever, because there is some ofset in voltage level on A and B line.

See scope of measurement with disturbtion:
Green = Math A-B
Red = A
Blue = B

PS: maybe A and B chanels are swapped - i don't know right now.

Can anybody help me suppres that disturbtion on RS485 ?.

So far I tried:
1) Replace 0R serial resistors in A and B line with ferite beads
2) I tried remove capacitor between Isolated Ground and Shield
3) I tried remove failsafe resistors R271 and R270, because they should be
   integrated in ISO1412
4) I twisted A and B wires

Nothink from above list help me solve the issue.

Any others ideas? Please...

Datasheet for ISO1412


texts: What's the easiest way to control a TI Launchpad (MSP430) from Linux over USB? I just want to use the board to drive some LEDs while it's tethered to my computer, so I'm looking for a way to simply control the output pins via a TTY or mspdebug or similar. I don't have a crystal on my board yet, but can add one if needed.


texts: Is it safe to use narrow but short PCB traces for high current flow?

texts:
I am trying to design a PCB which has high current traces on it.

PCB has 1 oz (35 um) trace thickness. Maximum current flow is going to be 12 Amps RMS.

I found this online PCB thickness calculator: https://www.eeweb.com/toolbox/external-pcb-trace-max-current

According to this calculator 5mm width is enough to hold 15 Amps current flow at 70 °C. However, due to some design limitations I need to get the PCB trace narrower as 2mm.

For 2mm width trace, the calculator points that it can hold 11.2 Amps current flow at 125 °C which is too high. To demonstrate the situation please look at the PCB layout below:

My question is, what happens if I put this PCB on work? I tried to keep narrow high current lines as short as possible but they are inevidable. I want to think that the thermal rise on narrow lines will be distributed over wide lines since they are conducted however, I am not really sure what will happen. Will those narrow lines burn out somehow? If so what are your practical advices?


texts:
I'm in the process of designing a headphone amp for my car (long story). It's been a long long time since I touched on electronics so I've been doing a lot of reading on the topic of amps etc.
The following design works when tested on a breadboard:

This design is an amalgamation of a load of other suggestions I've found online. Whilst it works well I find it starts distorting (particularly on bass) beyond 3/5 volume from my laptop. From my limited knowledge bringing down the gain on the op-amp and bumping up the power stage would solve this... I think?
My understanding is that my 4.5V split rail setup will only go so far without going to a bridged setup (which I can't really do due to other practical reasons). What dictates the power throughput of the power section? I've been reading up on transistors and if I understand correctly the hFE could be what determines amplification?
Would a different set of transistors give me a slight bump in output power? I'm not looking for a huge amount, just enough to give the op-amp a bit more headroom by not running at such a high gain.
Or I could also have misunderstood how the power stage works entirely, in which case any feedback on the circuit is most welcome!
Thanks!


texts:
The Minicircuits RAM-8+ amplifier has been replaced by the pin compatible RAM-8A+ part.  The old RAM-8+ part was conditionally stable and I had to use an extra output attenuator after the amplifier to ensure that it did not oscillate during open-circuit output conditions.

It appears from the Minicircuit supplied S-parameters plotted in terms of the stability factor k and the geometric stability factor μ that the new RAM-8A+ is completely stable across the operational band; however it does have sharp dip in μ at 50 MHz that approaches the unconditional stability limit line of 1.

I would like to test the new amplifier under stressed conditions to verify that it is indeed stable.  My initial thought for a test setup would be a directional coupler on the RAM-8A+ output with the thru port alternated between open and short, while monitoring the coupled port for signs of instability.  I'm curious if there are any other good setups for testing the stability of such an amplifier, e.g. monitoring the drain feed with a oscilloscope under open/short load conditions?


texts: RMS value calculation using micro-controller

texts:
how to calculate the RMS value of an AC signal (220v,50c/s) using micro-controller.
i m using stm32f3 controller and its A/D convertor has 72MHZ clock frequency.


texts: Do Protected Power MOSFETs need a flyback diodes?

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There are protected MOSFETs under various marketing names available (e.g. omnifet, hitfet, intellifet, etc). These devices include clamping diodes and overcurrent/temperature protection. They also seem to suggest that inductive loads can be connected directly:

Infineon-BSP78:
Datasheet

AND8202:

  ClampFET topologies utilize ESD protection at the gate input  and  active  gate  to  drain  clamping  (described  later), useful when switching inductive loads. [...] All topologies drive any type of resistive or inductive load such as solenoids, heater coils, and filament bulbs limited only by the current and thermal capability of the device

Usually flyback diodes are used directly across the inductive load (and not the MOSFET) to prevent voltage spikes if the transistor is turned off. Thanks to the overvoltage protection diodes the MOSFET should be safe, but other parts may not.

Should I use these protected MOSFETs without a flyback diode and what pitfalls may occur?


texts: The potentiometer used in electronics is not a measuring instrument. Why it is contains phrase 'meter'?

texts:
Why this kind of variable resistor is called a "meter", when it is not a measuring instrument?

I have seen another instrument of same name. In our school physics lab, there was a big rectangular, board-like, measuring instrument called a potentiometer, used to measure resistance.

Did the name of the 'electronic potentiometer' came from that 'measuring potentiometer'? If so, then are there other relations (not only the relation in name). What are the relations?

Fig: The diagram given, is the diagram of that measuring instrument from my old school textbook. AB is a long, uniform, cylindrical conductor rod (attached to a Wooden scale M) , on which there is a "Jockey" (wiping contact point). On A and B, voltage is applied using the battery E. (The commutator C used just to rapidly reverse the polarity).  Galvanometer G is used to detect a null point. The scale M is used to measure the ratio of AJ and JB.


texts: Valve motor seems to stall to open. Does this make sense?

texts:
This is the scenario: There's a valve controlled by what it looks to be an AC motor, specified as 220V 50Hz and 7W. That's all, there's no datasheet available and there's nothing else on the labels that talks about stall current or anything like that. The way this seems to work is that the motor shaft, through a whole lot of reduction gears, ends up moving a lever, which opens a valve (Normally closed with no current). The end position of the lever is determined by a metal plate that prevents it from going further. Hence I understand that at this point, the motor stalls. Once current is not applied to the motor anymore, a spring brings back the lever to its original position, which in turn closes the valve.
I said "it seems to" a few times because the motor is currently broken. Actually, there's two, and they are both broken, so a lot of this is my theory. Furthermore, this is all from a videocall with my dad who has the problem and is waiting for the replacement motors, but I'm trying to make sense of it, and even what the manufacturer told him doesn't click in my head very well.
So, two questions:

If a system is designed to stall the motor while the valve is opened, shouldn't there be something to limit the current to make sure it doesn't go past the stall current? This motor connects straight to the mains (220V 50Hz), no other electronics.
How is this design justified? Isn't the motor going to be consuming the maximum current while keeping the valve open? In this application it's supposed to be open for hours at a time*. I can only think that maybe the torque of the motor is needed to fight back the 1.6bar max pressure that it might encounter to keep the valve open, but even then, surely a design with some electromagnets or relays that fixes the lever mechanically, or a stepper motor or something like that would only require current flowing during the actual opening of the valve? There's even a way to move the lever manually and leave it latched so that the valve stays open.

It might be that my understanding of what I think it's an AC motor is not complete and actually when stalling there's really not that much current consumption?
If someone has experience on a scenario like this or could point to some good reading about this, I'd love to learn more about it.
*I mentioned earlier that its supposed to be opened for hours at a time. My dad had a chat with the manufacturer and he was told that they are not really designed to be used for those longer periods of time, therefore it is normal that people need to replace them. I can't think that this is just a case of something designed to be replaced, that doesn't make sense to me. The application is a time controlled heating system. It could run for an hour, or for 48 hours, why not?
Thanks!


texts:
In a car battery charger, I found a strange rectifier. Can someone explain to me how does it work?

Here I have a transformer which is unmarked. By measuring resistance between its output terminals, I determined that the plus cable is connected to the center of the transformer. The two outer connections both have a diode connected as shown on the image. To me it looks similar to this:

 rectifier, but the diodes are turned backwards. I checked their orientation several times with two different multimeters and I'm sure that I've drawn them correctly.


texts:
I know there are several solutions for V-USB using only DIP Parts (especially the ATtiny) like

IgorPlug

http://obdev.at/products/vusb/easylogger.html
http://cesko.host.sk/IgorPlugUSB/IgorPlug-USB%20%28AVR%29_eng.htm
http://www.recursion.jp/avrcdc/cdc-232.html

But they are limited to 38400bps!

Why?
Are there other solutions only using DIP packaged parts for easy soldering?


texts: Minimum PCB Trace width with SMD components and Autorouter problem

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I would like to receive some suggestions from you about the trace width for my PCB.
I'm using some SMD components (ATmega328p TQFP32 and FT232), the main power is 5VDC at maximum 2A. I use also a ESP Wi-Fi module, but the maximum current comsumption will be lower than 2A for sure.

My PCB manufacturer says that the minimum trace width should be 16 mils with copper thickness 105um.

I used an online calculator and it recommends to use a width of 7 mil for the external traces on the PCB (my PCB will use only two layers).

So, it is OK to set 16 mils for the traces?

Thank you and sorry if the question looks too much stupid.

This is the result of the Eagle autorouter and as it is possible to see the problem is with the SMD components. I think it's because the traces are still too wide for the SMD components pins.


texts:
I have a FOC controller for a servo motor, where the Iq current can overshoot the maximum allowed Iq current (That is the reference value limit for Iq) by around 80-100% under heavy dynamic load.
When I use the servo motor with a constant attached load and give position or velocity commands, the Iq current does never overshoot more than around 5%, also when I go for example from full speed 3000rpm to -3000rpm.
In the used application however, the load changes dynamically, such that the servo first is fully in generator mode, then goes fully in motor mode and then suddenly with full force again into generator mode. The change from the motor mode into the generator mode leads to the overshoot of around 80-100% as seen in the following graphs.
My PI current controller is automatically tuned, by using the phase resistance and inductance to achieve a linear plant of the motor and then the bandwidth is chosen, such that the motor runs smooth enough. When I actually increase the bandwidth, the overshoot is less, but the noise of the motor increases.
So my questions are:

Is this a normal behaviour or may there be something wrong?
As you can see in the second picture, the iq integrator sum increases in the motor mode of the servo and when suddenly the load change appears and the servo goes into the generator mode, the overshoot occurs as long as the integrator needs to adjust the value.
How fast is normally an integrator in the current loop? In our controller, the delay from 20V to 0V seems to be around 150ms at that seems to be the reason for the overshoot.


texts: Relationship between voltage/current & LED strips?

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I recently bought a WS2812 LED strip (5 meters, 300 LEDs)

When the LEDs are driven at full brightness and each color lit, they draw 60mA each--or 18 amps for all 300!

This led to a problem, which led to a question.

A friend suggested that I not attempt to power the whole strip at once, because even if I could, 18 amps would probably burn it up. So, the other option is to splice in power leads every so often, which is recommended by the manufacturer.

I took a look at my power supply and realized that while it can supply between 0-24vdc, it can only supply 5 amps.

Is there no difference between 12v at 5 amps, and 5v at 5 amps other than power? I understand that Power = amps * volts, so 12v at 5 amps is 60 watts, and 5v at 5 amps is only 25 watts. My question is this: shouldn't the limiting factor be the wattage, not the current? If my power supply can supply 24v at 5 amps (it can), this is 120 watts. In order to supply 120 watts at 5 volts, I would be hitting 24 amps.


texts:
I put together the following simple subtractor circuit:

Problem is, I see 0V at the non-inverting input of U2, no matter what.

I added U1 (buffer), moved positions in the breadboard, removed C3, and swapped out the LMP7721 in exchange for an LM324 as attempts to fix this, but to no avail. If either R9 or C3 are connected to GND, I see 0V all along that node. It works just fine in LTSpice, so I'm at a bit of a loss.

What am I missing?

EDIT - 2/Oct

Shown below is my previous design, which worked just fine (I've only changed it to try and subtract out ambient noise). I tested my WE against this circuit and I see the voltage range I expect.


texts:
I am making a homemade capacitor for a project. I got the plans from this link. I am making the 60μF simple electrolytic capacitor. I have made it, but:

How would I charge the capacitor with a power source? Also, I have a 5V power source, so...
Will this 60μF capacitor hold this charge?
Could I disconnect the capacitor from the power source after it's charged, and will it still hold it's charge for a short amount of time?
How long do I wait for the 5V power source to charge the capacitor?


texts: questions about open circuit, pull up resistor and MOSFET selection

texts:
Please let me ask 3 questions about meaning of open circuit, calculation of pull up resistor value and selection of MOSFET.

I'm trying to understand how to use the TPS3808G33 reset IC and the followings are the questions. It might be obvious to most of people here, but as a beginner in engineering I couldn't find answer by myself..It would be very helpful for me if you could give answers.

On page 4. the description of C_t pin says that 'leaving it open results in fixed delay times'. Then would it be okay to connect the C_t pin  directly(or through a resistor) to GND?
On page 4. the description of RESET pin says that 'A pull-up resistor from 10kΩ to 1MΩ should be used on this pin'. Could you please explain how to calculate proper value of this pull up resistor for TPS3808G33? In figure 10 they used 1MΩ for TPS3808G25, but I have no idea how to determine the value. ...Could I just use any value between 10k~1MΩ?
On page 8, it's written that 'To minimize current draw, a logic-level FET can be used". But... could I use any N-channel MSFET? The data sheet didn't mention about it.

Thank you in advance.


texts:
I am trying to interface to an existing device, for which I do not have documentation.  The device exposes a 5v I2C interface with several IC's on the bus.  I have used a logic analyzer to capture the traffic, and do not understand why my writes are not being accepted.

Working system:

Unknown microcontroller  ==| connector |==+== PIC 12F509 with internal oscillator
                                          |== 24C16WI 2k EEPROM
                                          \== Logic analyzer

The first communication with the device is to send a write request to address 0x49, but when I attempt to do the same, I do not receive a response.  There are obvious timing differences in my request versus theirs, but I am not sure if they are significant.  Communication with the 24C16WI is successful, but I can get no response from the PIC.

Working request (baud rate 36kHz) (Saleae capture):

My request (baud rate 31kHz) (Saleae capture):

Assuming that the difference does not rely upon a signal other than the I2C lines, are the timing differences in the signal significant?  If they are significant, how can I generate the required timing using an Atmel SAMD21J18?

What am I missing?


texts: How to make a voltage multiplier of 1.075

texts: I have an 80v power supply that's rated to put out 18 amps, and I'm planning on using it to charge an 80v battery pack. Unfortunately the pack's charge voltage is 86v, so what I'm wandering about is how to make a voltage multiplier that can multiply the 80v by 1.075, I was looking at making a Charge Pump but I don't know how to make anything other than a doubler, http://en.m.wikipedia.org/wiki/Charge_pump any advise welcome. Thanks


texts: What are the exact meanings of reactive and apparent powers? Do we say they are supplied or consumed?

texts:
(The following doubt is from the topic of Sinusoidal Steady-State Analysis of electrical circuits)
I understand the meaning of real power - it is the average power consumed (or delivered) by an element in a circuit. But I do not get what reactive power is? From talking to people, what I have understood is - it has no real significance, but it is some quantity defined to ease the process of circuital analysis. Is this understanding of mine wrong? If it is wrong, can I please know the EXACT significance of it? Having understood the meaning and significance of the reactive power, can I also know the meaning and significance of apparent power?
Also, please go through the below picture:
In the following picture, "Element" can be anything - a voltage source, current source, resistor, impedance etc.

So I am also not able to comfortably use the terms supplied and consumed in case of apparent and reactive powers. If someone can help me understand my doubts, it would be really helpful! It would be also helpful if links to some useful reading material are provided. Thank you!


texts:
My question is how can i recover the clock timing of digital audio transmitted over ethernet using UDP?

I am streaming live audio over Ethernet using UDP. My set up uses two STM32F407 discovery boards, one for transmit the other receives. I can hear the audio data which i am outputting from the discovery board codec. When i use the logic analyser i can see the word select is out of sync with the data.
The delay between transmit and receive is 1mS. 32bit, 44KHz sample clock.
The audio sounds ok when people are speaking but loud noises create distortion. When music is played the higher frequencies are distorted. At moderate voice levels the system sounds ok.

Does any have or know of any algorythm for clock recovery from UDP data?
Would careful timing of the transmitted frames make things easier?

Thanks in advance
David


texts: Makefile error while compiling LwbT using TI Microcontroller IDE

texts:
I am trying to port Lwbt to TI MSP430 Microcontroller. As a first step, I am compiling the lwbt in TI Code Composer studio as a Standard C Make Project. I have downloaded the lwbt code from https://github.com/lwalkera/lwBT. I have set the path for build directory and build commands. I have also downloaded Mingw. GCC works fine which I checked by typing gcc in the command prompt. But while building the project, I get the below error.

gmake -f Makefile all
process_begin: CreateProcess(NULL, cat filelist, ...) failed.
process_begin: CreateProcess(NULL, cat filelist, ...) failed.
--[OUT]--
gcc: no input files
gmake: *** [lwbt.out] Error 1

I have been struggling with this error for last 1 week. Desperate for help.

Thanks


texts: How can I analyze an op-amp based negative impedance converter in a circuit?

texts:
I am thinking of the circuit pictured below, which, while the op-amp is operating in its linear region, gives rise to the relation

$$
v_0 - v_1 = -i_0 r ,
$$

where the direction of positive current is indicated on the diagram below. The thing that's really bugging me is that I also have the relation

$$
i_1 = - i_0 ;
$$

that is, if \$ i_0 \$ is flowing into the NIC, then \$ i_1 \$ is also flowing into it. This really disturbs me because it means that I can't black-box this as a single-port circuit element --- charge isn't conserved. This is exactly what Wikipedia seems to be doing, however, when discussing Chua's Circuit.

Have I made an algebra error; that is, is \$ i_1 = - i_0 \$ not true? Or is there some method of dealing with a dually-emitting source like this? Again, I'm trying to get at Chua's Circuit, so if you would like to conduct an example analysis for me, that would be a prime target. Alternatively, I think that if you hook this guy to a capacitor then you get an oscillator of some sort, so that would make for a more compact example.

Thanks in advance for any help I can get on this. If anything needs clarifying, I would be more than happy to explain myself to you.


texts: How do I generate the described pulse signal in Matlab (Simulink)?

texts:
I want to implement the following signal:

I(t) = 500*(sin(pi.t/0.3))^2, t belongs {0,Ts}

= 0, t belongs {Ts,T}

Here, T = 0.8 and Ts = 0.3

The code I tried:

t = 0 : 0.001 : 25;
d = 0 : 0.8 : 25;
y = pulstran(t,d,'rectpuls',0.3);
ut = 500.*((sin(pi*t/0.3)).^2).*y;
plot(t,ut)
xlabel 'Time (s)', ylabel Waveform

The generated waveform deforms greatly, for example the generated waveform does not consist of uniformly spaced peaks.

Edit:  Modified the code but still issues remain.

    t = 0.01 * [0:3000]';
    d = 0.8 * [0:1500]';
    y = pulstran(t,d,'rectpuls',0.3);
    ut = 500.*((sin(pi*(t-floor(t/0.8)*0.8)/0.3)).^2).*y;
    plot(t,ut)

Mainly, instead of 1 peak for the 0.3s ON state, there are two peaks.


texts: Configuration of Multiple Buck Regulators on One PCB

texts:
I have been doing a lot of switching regulator research for a board design that uses two buck regulators on the PCB to get 9V and 3.3V out from a 12-28V DC supply. The majority of my questions have been answered but a few questions I am not finding satisfying answers to.

I am trying to decide how to configure the 2 buck regulators based on possible switching frequency and what voltage source to use as inputs to the regulators.

To preface, the board design this is for is a basic analog input and relay output-control board that has RS485 and Ethernet on it. The analog input circuitry and relays use the 9V rail (segmented from each other though). The MCU and other ICs use the 3.3V rail. The system in total consumes about 1 amp max and both the 9V and the 3.3V need to supply 500mA each.

1) I am considering using the same regulator model TI TPS54231DR for both output voltage needs (9V and 3.3V). I already have a lot of these on hand so that would be ideal. But the following links talk about beat frequencies appearing when the switching frequencies of the regulators are close together (The manufacturing variance will cause the two components to have slightly different switching frequencies). I am slightly concerned of this for the analog inputs.

Link1

Link2 - here is the relevant screenshot...

Now I see that the links above suggest using inductors with a few ohms of resistance at the switch frequency to combat the beat frequencies, which I can do.

But this begs the question...how much of a difference of switching frequency is needed for the beat frequencies to not be noticeable? The regulator I already have is 570Khz and I see other switching frequencies in the 400-500KHz range and the 600-800KHz range. Is a 100-200KHz difference between the switching frequencies enough to not notice the beat frequencies? Would 50KHz difference be enough? I don't have all the components on hand to test this all out.

2) For the regulated voltages on the PCB, is it better (less noise, more stable) to have all switching regulators use the main supply rail as their inputs? Or can they be cascaded (the output of one buck goes to the input of another)? If I can cascade them, then I can use a 3.3 Output buck regulator with a lower Vin MAX which again, I already have on-hand in mass quantities TI TPS62152RGTT. They have an input voltage max of 17V and switching frequency of 2.5MHz. In the cascade model, I am curious as to whether or not the switching of the 3.3V regulator will add noise to the 9V rail. If it will, I think I would rather just have the 3.3 outputting regulator attach to the 12-28V supply.

3) And relating the two questions...what would the noise impact be of using the cascading configuration with the same regulator model? Does this cause the beat frequencies to be seen in all the supply rails?

In summary, I guess what I am asking is which of the 4 following configurations is best option? My preferred options would be A or D for BOM simplicity, but I can also accomplish configuration C with parts I already have at my disposal.


texts:
The SAM3X8E has a MPU, what I am confused about is how to combine both SRAM and FLASH into the same protected memory region since they live at different contiguous region addresses.
Is this possible?
I am interested in implementing a custom bootloader/system recovery code which would keep a little bit of ram I want to remain protected from potentially broken user uploaded code.


texts: Run Ngspice in batch mode or with python

texts:
For circuit simulations I have mostly been using LTSpice, where the netlist is generated automatically with a python script I wrote and run using the following python command:
subprocess.run([ltspice_executable, -b, my_netlist])(1).
The voltages of my circuit are extracted by reading the generated raw files using the python package: ltspice.
Now I have to move to NgSpice (@Related question with no answers here). My LTSpice netlist only contains resistors inductors and capacitors so it could basically run in NgSpice with no problem whatsoever.
I would like to know please if there is a similar python command to the one I use for LTSpice (expression(1)) so as to run NgSpice from my python script and extract my voltages?


texts:
I took apart a microwave, and when I saw the magnetron, I conviniently remembered that I had heard that magnetrons  were dangerous. I decided to research this a bit further (I know, great timing) and I found that some magnetrons contains berilyum oxide, which is fatal if you breathe it in. I also read that it is dangerous in this way only if it's crushed, then inhaled. (It is also lethal if if you ingest it, but I'm not planning on doing that).

Since we stopped using that microwave, I haven't dropped it on the floor or anything like that, so does that mean that it is safe to handle? How could the magnetron become dangerous? What precautions should I take to make sure that I'm safe?


texts: Electronics course - From basics to designing circuits

texts:
Possible Duplicate:
From zero to “almost pro”: Newbie trying to learn. Good, quick resources?
What good resources are there for a high school student to start learning electronics?

I am trying to learn electronics. I have a number of books and have been through the basics

Ohms Law
Resistors
Capacitors
Diodes
Etc...

The books I have go through these fundamentals quite well but then they show some circuits for me to build. I would like to learn how to design a circuit and not just copy an existing one.
For example, I know what capacitors are and how they work but I have no idea how to design them into a DC circuit.
Is there a good Electronics course online or a good book which will teach me.


texts:
From what I am able to understand, a voltage controlled oscillator is "controlled by a voltage" when this voltage is applied to vary the value of the tank circuit: e.g. this could happen by applying this voltage on a varicap diode, which change its capacitance according to the voltage.

However I also noticed another thing: I have assembled a very simple oscillator based on a transistor and a handful of components: it is very basic and weak (I found the schematic in a book for beginners,) and I have noticed that if I vary the value of the power supply, the oscillator will vary/drift the working frequency (I have verified this, since a friend of mine has good equipment at his lab.)

So, can this oscillator be called VCO, or is just a "feature" due the weakness/instability of the circuit? Also, why will the frequency vary according to the value of the power supply? I was also thinking, if I apply a sawtooth waveform as power supply, will the oscillator automatically drift on its frequency range? I ask this also because I'm studying this kind of modulation.

Please consider the fact that I am a beginner, so I will appreciate an exhaustive answer also with practical examples/schematics.

Unfortunately, since the schematic of my oscillator is only in the book, and I don't have a scanner in my printer, I can't post the exact schematic.

However my circuit looks very similar to this one, except for the fact that I don't have a mic, and in parallel with C1 there is another resistor.


texts: Do SD cards operating at 1.8V save any power compared to 2.7 - 3.6V?

texts:
Excuse me if I'm repeating my previous question, but it wasn't getting any answers probably because it was too broad.

So, let me narrow the question down to just UHS SD cards that can operate at 1.8V (internally, they still use a charge pump to raise the voltage for writes).

How much power can you expect to save or lose compared to operating at the standard 2.7 - 3.6V?

I was hoping to use it for my battery powered wild life camera, but after some investigation, I'm seeing 2 huge setbacks:

the complexity - all SD cards need to be initialized at 2.7 - 3.6V, probably for backwards compatibility. After that, a CMD5 is sent requesting 1.8V operation. Then the voltage to the SD card is lowered to 1.8V. Likewise, the processor will need to either lower its I/O voltage or use a level translator.

To me, this is hopelessly complicated, hardware wise. I did find some chips that conveniently have both a configurable DC-DC converter (to select 1.8V or 3V) and level shifters:

ST6G3244ME

Similar: NXP IP4855CX25

But I don't want to use another chip since I'm only working on this as a hobby and am already very constrained by my 1 layer PCB.

Also note that the voltage converter on that chip is an inefficient linear regulator, which brings us to the next issue.

It seems using 1.8V will use the same or even more power than the 2.7V due to voltage conversion losses.

Why? Clearly, 1.8V will reduce the I/O power between the card and the processor. But that requires either an extra regulator to step 2.7V down to 1.8V or use a single regulator that supplies 1.8V to both the SD card and the processor (microcontroller in my case).

I've looked at some switched capacitor regulator (charge pump) data sheets, and  the efficiency decreases as the absolute difference between the output and input voltage increases. This makes sense because the closer the input and output voltage, the less the regulator needs to charge/discharge the capacitor(s) and it's well known that charging a capacitor wastes 1/2 the energy.

Therefore, it seems you're actually wasting power by using 1.8V since the conversion from 3.7 (battery) to 1.8V is now more wasteful. Furthermore, the charge pump inside the SD card will also get more inefficient?

Are there alternate solutions that avoid these problems?
Are there any SD cards that don't require you to start at 2.7 - 3.6V?

If 1.8V doesn't save power, then what's the purpose?

Note: there's 1 externality that I'm considering. Using 1.8V can reduce the conversion losses for the microcontroller, which runs at 1.3V internally. Not sure if it's a net gain.


texts:
Connecting a small-signal N-channel MOSFET and a power NPN BJT like this darlington-ish configuration, what does it produce? Is it equivalent to what people call IGBT? What about its P-channel counterpart?

simulate this circuit – Schematic created using CircuitLab


texts: EEPROM being both "programmable" and "read-only"

texts: Since it is called programmable, I tend to think that it should also be named with the write option. What is the deal here?


texts: Logisim - Tunnel that outputs the OR result of all of its inputs

texts:
Consider this screenshot:

When the two values differ, I get this:

This makes sense, but it's a problem. I would like the tunnel to function like this: when it's getting mixed values, it outputs the OR result of the values instead of an error value. So, in the case of the above image, the tunnel's output would be '1'. Will I have to spam OR gates and a bunch of different tunnels to do this, or is there a built in tool/plugin I can use to do it for me?


texts: Repairing a failed generic AC/DC power supply which "ticks"

texts:
This type of death affects a lot of power supplies, Computer power supplies, Monitors, and other mains powered equipment that is stepped down to low voltage, high ampage DC.

On plugging in, the psu board makes a ticking sound (sounds a bit like static), every half second or so (but slightly irregular) - and when un-plugged the ticking slows down and stops, Assumed to be a capacitor draining.
Usually showing no obvious visual defects, no dry joints, burnt tracks, hot spots, burned out transistors etc...

What could cause a PSU board to make this ticking sound?

please note the sound refereed to sounds like static, but no arking can be seen, it is not coming from a relay. It is irregular so is highly unlikely to be a startup protection cutout.

An example of a generic PSU:


texts: Does an electrolytic capacitor have a minimum voltage?

texts: Do electrolytic capacitors have a minimum voltage below which they won't operate? I'm pretty sure they don't, but anything below 7V and 1A will not power the circuit below when the capacitor in added.


texts:
The arduino mini consumes 5V. The Voltage input is min. 7V.

Is it possible to ignore that and attach 3 AA batteries (4.5V) or 4AA Batteries 6V between the GND and 5V pin of an arduino mini for long term wireless use?


texts: Recently I have heard that KCL and KVL do not fully apply when performing electrical measurement on PCB traces. It was implied that PCBs are not completely lumped circuits - that is, we cannot assume the speed of light to be infinite while dealing with them at an appropriate precision. What could that mean?


texts: Comparator H Bridge current sense negative voltage input

texts:
I'm using lm339 basic comparator to sense current from an H Bridge. Current limiting was done somewhat successfully with acs712 after removing the capacitor from filter pin for limiting the bandwith. It was connected after the h bridge ground and far from the big capacitor negative leg.
Did research and looking at the infineon application notice for mosfet gate drivers and also fairchild one. Also looked at ti's document for he bridge.
There is a fact that input voltage will go below ground for the comparator input. Here is a link to another post from eexchange.
Lm339 datasheet states multiple times that going below ground will not do it any good, to say the least. Also saw the circuit with zener clamp and resistors on the comparator input. However the 1 to 100 k resistors would really slow down the comparator due to parasitics.
Maybe it is a good thing to slow it down, to make sure that inductive kick is ignored and comparator picks up only the useful voltage from the shunt later?
Here is a schematic:

Now is there any solution besides zener clamp didoes. Maybe schottky between shunt and comparator input?
The circuit will be running blazing hot because of the high value of shunts, but the leakage current from schottky diode may impose a problem on lm339.
H Bridge is intended to operate at 48 Volts and 5 Amps peak.


texts:
I have a question about the instantiation.
Like the picture shown below, if my main code is 3.vhd.
I want to instantiate entity aaa and bbb in entity MAIN.
Is the rule that I should write the "component" in "package", like 1.vhd shows?
(My understanding is, all the entity should have its package, if it'll be instantiated. And the component just list the port of this entity.)
After that, add "use package.all", and then we can instantiate aaa and bbb in MAIN's architecture.
Is there anything wrong?

I'm not familiar with VHDL, but seems verilog didn't have this "package" thing.
A module can be instantiated in another modules.

Thanks! :)


texts: Where do I place the on/off switch in a multi voltage circuit?

texts:
I've got a simple Arduino setup where I need to supply a 3.3V Arduino with adequate power - and at the same time provide higher voltage to a sensor which needs 5V.

The Arduino is powered by bypassing the regulator (via VCC, not RAW pin). Connecting it to 3 of 4 batteries thus provides it with a range of roughly 4.5V - 2.7V over the life of the batteries. (Tolerance for ATMega 328P is 1.8V to 5.5V)

The Sensor needs a minimum of ~4.5Volts (up to 12V and more) and I solve this by adding another battery, adding voltage up to 6V (3.6V when batteries are empty, so it will start to behave erratic earlier).

Where do I place the switch in such a multiple batteries, multi voltages circuit?

Having it on the VCC/positive lines would mean I need a switch that cuts/connects two lines at once, a Double Pole Single Throw (DPST) switch.

Having a switch on the GND/negative line would break the circuit, but I've read that connecting VCC first (which this would effectively do) is bad practice and might damage components (which it seems it doesn't in my case, I tried it, but still..). Also would it drain batteries somehow?

Please,

for now, do not suggest changing the circuit altogether, for example with a step-up converter for the sensor. I need to keep voltage fluctuation down in its circuit (I think), in a simple way. I left out radio in the schematic above. TX would cause a drop in voltage and disturb the sensor. Also, running the Arduino at 5V with a step-up for the whole circuit seems to be no option. The added battery for the sensor equalizes voltage and/or noise (?) in the circuit, it simply works (at least from my novice point of view) and one monolithic power source didn't, in my tests. Something from the step up disturbed the sensor as well and my trial and error experiments with capacitors didn't solve it. Also, more back and forth: having the Arduino behind a regulator means I can't measure battery without external voltage divider.

Just a little side-question:

I've measured that the 3 batteries drain a little faster than the one "sensor-battery". Means: the added single battery would always have voltage above the pack of three. Is this a safe circuit? Or will there be something like inverse voltage at some point? Or will my batteries melt when they start to get more disparate/unbalanced?


texts:
I need to trigger a speaker if my input voltage is higher than 0.6 V, otherwise the speaker must not be triggered. That's the reason I'm using an AMPOP Comparator:

and, as far as I know, the voltage Vout should be:

$$  V_{\text{out}} = \begin{cases} V_{\text{S}+} & \text{if } V_1 > V_2, \\ V_{\text{S}-} & \text{if } V_1 < V_2, \\ 0 & \text{if } V_1 = V_2\end{cases}$$

But when I simulate my circuit, my output voltage is not Vs+ or Vs-. There is a loss in voltage and you can check all voltages on the following image.

V1 = 1 V and V2 = 0.6 V, Vout = 13.011, but Vs+ = 15 V;

V1 = 0.2 V and V2 = 0.6, Vout = 1.9889, but Vs- = 0 V.

I need Vout near 15 V (and 0 V if V1 < V2). It doesn't have to be exactly 15 volts, but near it. Am I doing something wrong? Is there any way to do it without another amplifier after the output? I'm beginner sorry if I misunderstood something.

BTW, if you know an easier way to trigger the speaker, tell me ;)


texts:
I'm starting my first PCB using Altium and I want to take advantage of small dimensions PCBs cost in order to make my PCB cheaper. As an example take the image below. On the left there's the full PCB and, on the right, I'm splitting it just to make it cheaper (that's not my design, just an example).

Let's assume that the new PCBs follow manufacturer rules, I'm just wondering if, in order to use those small PCBs discounts, I have to design 4 different schematics.

EDIT
Let's take an example. There's a really low price on 10x10 PCBs but yours is 10x20 (which costs 4 times more then a 10x10), but it can be split in half (two 10x10 pcb). Instead of paying the much higer price for the 10x20, I want to able to design a line in Altium and, somehow, make it generate 2 different PCBs.


texts:
Our pcb current consumption is less than 0.5mA . We use a 3.7v lithium battery, and the battery goes through voltage regulator LD6806 that has a low dropout voltage ,and its output is the main 3v3 supply of the circuit .

The problem is , that we start to suspect that this regulator, is consuming more current than expected for some reason , and so our pcb now consumes more than expected.

This might be stupid assumption, but how can you check on the data sheet, whats the current consumption-the unwanted current- of this regulator, that is added to the original circuit current consumption ?


texts: Summing stereo to mono without high frequency distortion

texts: just wondering how to sum stereo to mono signal? I am aware that you can use resistors in series to the left and right outputs of say a Bluetooth receiver module but when i do this, the channel does sum but the quality is horrendous on the high frequencies, sounds like a low bit rate mp3? Does anyone have a solution to this? The parts that i am using is a sure 30watt mono amp, and a sure Bluetooth receiver module 4.0 aptx etc... Thanks i would really appreciate this as i have been pulling my hair on this speaker build


texts: Capacitor charge circuit - 0V drop switch?

texts:
I have a capacitor charging from a supply voltage by a resistor and diode (resistor to limit current and diode to prevent energy flowing backwards when supply voltage drops).

The voltage drop on the diode is 0.18V. The cap rating and the supply voltage are the same.

I want to eliminate the voltage drop to gain the extra energy storage, without having to resort to something like a boost converter. Is there a simple way?


texts: We have been using the Allegro A6276ELWTR-T. This is a 16 channel LED cathode driver with serial data input and current control. Allegro is shutting their fab and discontinuing this part. Any one have suggestions for a good replacement? 8-16 channels would be ideal and the part must be surface mount.


texts: Best place to report an LTSpice XVII crasher?

texts:
I have a small LTspice XV11 .asc file that reliably gives a SIGSEGV when I run the simulator under macOS 10.14.3 (Mojave).

This is related to LTSpice IV for OS X (oct 2, 2018 version) crashes on macOS Mojave 10.14, except:

I have updated to the "Feb  7 2019, 11:03:59 US Pacific" release
The email address for Mike Engelhardt is no longer listed in the about box of LTspice (at least, not on the macOS version)

At the risk of asking two questions in one post, here's a link to the .asc file in case anyone wants to replicate the bug:

https://drive.google.com/file/d/1JCn2yEk1XB7FvNAyWjqBhhO60fnvhZno/view?usp=sharing


texts: What is the effect of connecting the tip of an oscilloscope probe to a ground lead? Here is one of the few links that I've found that shows the set-up: The Shorted Scope Probe. What are the possible uses of such set-up and what is the cause for the behaviour one might observe when shorting the probe (reduced susceptibility to environment noise, etc.)?


texts: STM32 - developing code without controller

texts:
Is it possible to develop a code for STM32 (hobbyist) without controller attached and test it? Is there a simulator mode or some other possibility? I do not have enough space to let the project "unpacked" and "fixed costs" of assembling and disassembling would take most of the dedicated time.
I am using CubeMX and TrueStudio to develop (or at least I am trying.)


texts: What is the purpose of transistors in the feedback of this OP-AMP?

texts:
What is the purpose of the transistors in the feedback arrangement of this OP-AMP?

I am mostly interested in the purpose and general use of this kind of "trick", and perhaps also what it does in the circuit where I saw it.
The circuit occurs in a bass-boosting audio circuit "DBX 100" of which the schematics are found here:
https://elektrotanya.com/dbx_100-boom-box_main_schematics.pdf/download.html

There's a similar arrangement discussed here, Op amp with transistor in feedback, but I'd like to better understand the specific role of the transistor.
Maybe hysteresis? Diode in positive feedback?


texts: Altium Default Clearance between Polygon and trace

texts:
Recently I have found difficulties to control clearance between Polygon and Trace/track when pouring a layer on one of our PCB.
I found out that clearance is much smaller than usual. I checked the electrical clearance design rules and all unactivated them to verify that this problem was not coming from design rules but still.

Any idea where those persisting settings may be set  ?


texts: Can my damaged Braun electric toothbrush with Duracell batteries explode?

texts:
I have a Braun toothbrush with 2 Duracell AA LR6/MX15000 (brand name Turbo Max), and today, the battery lid on the toothbrush broke, so I'm fearing that water might get in, and cause an explosion? I've just started using the batteries, so they're fully charged.

Sorry if this is a stupid question, I have no background in electrical engineering whatsoever, and I'm worried about the safety.

I don't really care if the toothbrush or batteries die for good, I'll get a new one next time I see it in the store.


texts: Best way to linearly step-up MCU output 0-3.3V to 0-5V

texts:
I am about to move from Arduino to my own MCU platform and am currently looking at the likes of the ARM Cortex M7 and M0+. One of my worries is that these microcontrollers seem to be only capable of outputting 3.3V. I need to send digital, PWM and analog signals scaling up to 5V, for example a throttle signal going from 1 to 4V. What would be the best, most efficient way of doing that?
Thank you!


texts: Why do I get "Supplier Disabled" in my Altium BOM

texts:
I am trying to generate a BOM of my Altium project so that I can send it to the procurement people.

However, strangely when I go into Reports > Bill of Materials about half of the Manufacturer 1 and Manufacturer Part Number 1 fields have "Supplier Disabled" in them. I've included a snippet below:

When I try to click on the supplier part number, it takes me to the supplier's website but searches for Supplier Disabled.
For Example...

I can't figure out why Altium is doing this.


texts: Texas Instruments Page/Register Convention - how to find the actual register address?

texts:
I am having troubles understanding TI datasheets regarding their DACs... I haven't felt so stupid for quite a while!

To make things as transparent as possible, here is a very literal question.

I am using Texas Instruments' DAC PCM5122. I would like to configure this DAC via I2C, and I'd like to program my MCU in C to configure it and stream data to it via I2S.

So, let's say I'd like to mute the left DAC channel... the way to do this is to set the RQML bit in the Page 0 / Register 3

This page/register convention is something I haven't faced before and it's awfully confusing to me!

The steps I would undertake, in achieving my goal using I2C interface, are:

1) I would firstly send the START condition;

2) followed by the chip address followed by a write-bit: i.e. 1001100[R/W] (binary);

3) followed by the register address;

4) followed by configuration data - just setting one bit, i.e. 00010000 (binary);

5) followed by the STOP condition.

Please feel free to correct me on any of the points above, if you should find them incorrect.

The question, of course, is what is the needed register address in this case?
Or, in general, how do I transform the given information (Page A / register B) into an actual address?

Thanks!


texts:
I've seen metal "sticks" with a special end that let them fit snugly into a through-hole for when you want a contact but don't want to solder a wire into the hole. What are they called and where can I buy them?

I think they are called "Posts" and are used for prototyping, but searching "electrical post" on Google just doesn't cut it.


texts: From a flux point of view, how can we explain that the equivalent inductance is half when identical inductors are connected in parallel?

texts:
The equivalent inductance of 2 identical inductance connected in parallel ( ignoring mutual coupling) is half of the orginal .  This result is usually derived from the argument of identical voltage across parallel elements->Proof

I would like to know how can we derive the same result from a flux linkage point of view. Self inductance of any component is defined as the ratio of total flux linkage to the current which produces this flux. Isn't the flux linkage of the parallel combo same as the sum of flux linkages of individual inductors?

If so, wouldn't the total flux linkage be same as the original flux linkage with just one inductor. [ Reason: Each inductor carries half the current, hence half the flux linkage. Sum total of both the flux linkages remains the same]


texts: How can I connect a dynamic microphone to a computer's microphone jack?

texts:
I have a generic handheld dynamic microphone and I want to connect it to my laptop for voice chatting. Normally it should connect to an mic amp and then goes to soundcard's line-in jack.

But my laptop only have a mic jack. Also I've heard that there is a bias voltage around 5V in the mic jack, and the pin definition may vary for different soundcard. After sometime of research I come up with this convert cable. Will it work? If not, what should I do? Is mic amp a must?


texts: Switching High-power MOSFET in nanosecs with 5V Logic

texts:
I want to switch upto 36V and higher onto a piezo disc. Wideth of the pulse I want to apply is 250 nano-secs.(4 MHz - piezo resonant frequency )
I summarise the problems I face here.
I apply the pulse using monostable multi-vibrator,74hct221d and ne555 and passing it through 74hct14d.(These are not seen in the simulation.) I plan to use psmn041-80yl mosfet to switch as it can accept a 5V gate supply.
74hct14d can at the maximum supply upto 20mA load which is not adequate for the mosfet gate which needs in the least a few 100mA to switch in nano-secs. I tried using a fast transistor mmbt4403 for supplying increased current to mosfet gate. It is switching, it introduces a long turn-off delay, as it has a high storage time of 225 nano-secs. So, in spice simulation, I could not get better than 1.2 us switching time using 250 ns trigger signal. (This switching time is at the gate of the mosfet - see draft2 circuit and draft2-output).

Using a NMOS to switch at 5V logic and PMOS to switch at 36V power, I get result like draft1.png. Even in this case, it must be mentioned that the gate current spice simulation shows a couple of hundred mA, which cannot be supplied by 74hc14d.

If I directly apply 250ns pulse to the gate (for proof-of-concept - see draft3 circuit and draft3-output) in spice-simulation, I get about 300 ns switching time on mosfet which is manageable.But this cannot be done due to 74hc14d output current limitation.

And I cannot supply enough power to mosfet gate using a 5V logic, so cannot switch it without enhancing gate-current. Enhancing gate current with transistor or signal-mosfet introduces unacceptable delay. What options I have ?
I have seen related questions and answers and my simulations already try them out. I need help which addresses nano-secs switching. Thanks in advance.


texts: Is there any cap on electromagnetic waves on the amplitude a certain frequency can carry?how does the amplitude affect the wave interactions?


texts: Recommended approach to create a lead acid battery level circuit

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I want to build a battery level indicator circuit for a 12 V sealed lead acid battery.

The battery indicator circuit will have two functions:

It will power 4 LEDs to show the level of the battery
At the lowest level it should disconnect the load from the battery to prevent deep discharging. To achieve this, I'm considering using a MOSFET (IRLML6244) as a switch. (comments on this approach welcome)

So far I've seen predominately two approaches to achieve this. The first method uses zener diodes and transistors to switch the LEDs as shown here

The other method uses op-amps as comparators to switch the LEDs as used here

I can't really see a clear advantage of the one over the other. I think the components costs will be roughly similar, but maybe a bit more soldering when using the zener approach. Keeping in mind that I also want to switch the MOSFET, which of these methods (if any) is the recommended method to use in my battery indicator circuit?

Not sure if it makes a difference, but my load won't draw more than 1A.


texts: How to measure current with a multimeter? Currently getting inconsistent measurements

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I have a current controlled power supply giving out 8 A (at least that's what I'm setting), plugged into a cable (call it #1) which is then connected via screws&crimps to a copper coil (call it #2, 70 turns, 1.25 mm diameter, 25.4 m length) to generate a magnetic field.

At the crimps, with a multimeter with a 10 A max fuse, I measure 3.8 A. I am using croc clips on the screws.

If I connect the ground of the multimeter to the '-' terminal of the power supply, the reading becomes 5.5 A.

Why?

Is it normal that the multimeter does not read exactly the correct current? Should I trust that current or the one displayed on the power supply?

P.S. = cable #1 is probably not rated for 8 A. But that should not affect the current right?

simulate this circuit – Schematic created using CircuitLab

Image of test setup:


texts: hc05 advanced at commands control through software

texts:
those having hc-05 modules will know that to request an RSSI value you need to hold the button on the module down and then request the rssi using the at+inq command , is there any way to handle this by using software ? i am not sure what the button functionality is , i can access the at mode with it however it needs to be held to use the at+inq command .

this is a pic of the module i have and the datasheet is extremely irritating with lack of info it doesnt even show that the module has a button.