texts: Altium: the shortcut key +/- don't move me to the next layers

texts:
I have created multiple layers from the stack layer manager. Also created vias from layer 1 to 2, and 1 to 3. When I clicked okay, the layer image didn't get updated, meaning it didnt add the vias I created (not sure if this is normal).

My guess is that because the vias weren't created, altium can't move me to the next layers. But then again, I have the default vias between layer 1 and last layer.

Which brings us back to the main question, why is my shortcut keys not working?


texts:
I need to read a 0-6V buffered analog signal from a sensor with the ATXMega256A3BU ADC. With an external voltage reference I can measure voltage level up to about 3V. I'm going to realize a voltage divider but I need some help in finding the correct equivalent resistance of the voltage divider ( R1||R2 ) that is the voltage divider output inpedence.
Atmel says that in the worst case the ADC input resistance Rchannel is 4.5k and the S&H capacitor Csample is 5 pF.


texts:
Trying to load a .bin file into a 2732 ROM chip in Proteus.

Having trouble finding the exact layout of code I need for the .BIN file.

So far i have tried writing the following in notepad and saving it as .bin

00000001
00000000
00000001
00000001

and outputting the data at the first 4 address spaces but i doesnt seem to have 'loaded' in the data I entered.

Maybe iam missing something like a header or some other key words in my .BIN file.

Thanks in advance


texts: I'm building a PCB library for a BGA component but can't understand what this size meaning in datasheet. Can someone tell me the meaning of this symbol? Thanks.


texts:
I have a pump (6-12V 4-5W) that i want to power up with a generator (9V 1.5A).

I've calculate the current needed with : I = 5W/8V = 0.55A.
Next i've calculated the resistance needed : R = 9V / 0.55A = 16 Ohm
Finally i've take a 22 Ohm resistor that i plugged in serial.

Despite all of this the pump doesn't work..
But if i just power up the pump directly to the generator without a resistor it works.
Could you explain me why my method with the resistance doesn't work, and why it works without it ?
Thanks!


texts: How do you document your hardware design decisions?

texts:
How do you document your hardware decisions in the design phase?
How do you avoid having to ask yourself the following questions while reviewing an hardware design that you made in the past:

Why did a choose this component?
Why/how did I choose these particular parameters for this component?
What does this part of the circuit do?
What is the power dissipation through this component?
What is the total power consumption of this circuit?
Can I replace this component with this other one? Are there any equivalent components to this component? etc.

What is a good way to document your decisions and calculations during the design phase of a circuit? How do I get answers to the questions above without going again through hundreds of datasheet pages?

One way I could think of is to add notes in the schematic files (if your EDA supports it), but I wouldn't want to clutter the schematic with too much information.


texts: How to select resistor values for a current amplifier?

texts:
I'm designing a circuit with an NPN (2N4401) transistor connected to a PNP (2N4403) transistor to amplify the current inputed to the NPN base terminal. Also, the general design I am working with is depicted here

What I am wondering is what resistance values I would need in order to get roughly 200 mA at the PNP transistor's collector terminal. I am using 5 V at the "Trigger" pin, so 1 kOhm at the base would provide ~4.4 mA. Amplifying this would bring me to ~264 mA (with Hfe = 60). Now going through the PNP would amplify this current again to a ridiculously high value.

What is the correct way to find these resistance values?

Thanks!

Also original question posted with this ckt:


texts: How Do Batteries Behave In Series-Parallel (Verify)

texts:
Hi I am confused about How batteries behave in series and parallel. I read online and saw that as you stack more batteries in series, the voltage adds together and the mA's stay the same, and if you stack them in parallel, the mA's add together, and the voltages stay the same. But I have found nothing about series-parallel.

I am have assumed that the following two diagrams would be true based on how loads behave in series-parallel, but I am here to verify that the batteries will actually behave like this in practice, and that there are no hidden quirks in this setup.

1st Set: Parallel  -  -  -  2nd Set: Series

For The sake of this Illustration Lets Say:
 -------Battery:1.5V 100mA
 -------Lamp:3V 200mA

This Question is actually for a project that I am doing Which You can see Right >>>Here!<<<


texts:
I'm doing a PCB design which includes a Gigabit Ethernet 'coupler' - i.e coupling from one CAT 5e cable to another via my PCB (see sketch below)
My question is, how careful do I need to be with controlled impedance given that the PCB tracks will be quite short (in the order of 0.5") ?

I'm hoping to get away with 2-layer, 1.6mm FR4. Using any of the online edge coupled microstrip calculators, I'm coming up with a track width of 38mil with a spacing of 8mil which is just not going to fit!

Thanks!


texts:
I am making a testbench in Verilog where it will call different test cases from different modules, each module, one test case/task.
I am a beginner in making testbench, can I know where should I instantiate the DUT object? In the testbench file or in the task?


texts:
I'm making a solder fume extractor from an old PC fan (4-pin PWM), driven by a mid-range PIC.

The fan needs 12V @ max 0.28A for power and a 5V PWM @ max 5mA to control the RPM. So I'll be running the PIC at 5V and therefore I will need both 5V and 12V available. I assume the PIC won't consume much power compared to the fan, even though I plan to have an IR proximity sensor too so I can ramp up the fan speed when my hands move towards whatever I'm soldering and then ramp down again when I'm done.

I haven't yet decided whether to use a wall wart or batteries, but would like to know the pros and cons of the available options.

So, as an example, I assume I could power the system with a 5V wall wart and use a DC boost converter to get the 12V for the fan.

Or, I could power the system with a 12V wall wart and use a DC buck converter to get 5V for the PIC etc.

Apart from the cost and availability of parts, what criteria are there for deciding to go one way or the other? This is a one-off personal project, so commercial considerations are less important (although still interesting), I'm thinking there may be practical issues that I'm unaware of (e.g. noise between power rails, efficiency?).

Could someone give me some insight into how these decisions are made?


texts:
Boostedboards.com says they use twin brushless motors, total 2000W

Anybody know what they are? where I could get a couple? Guesses or pointers welcome, I'm not really familiar with small electric motors.


texts: How does single supply transimpedance opamp circuit works

texts:
Was going through this webpage and noticed that a trans-impedance amplifier using single supply. However, I am unable to understand how it would work?

How would the opamp see inverting input(photodiode - on non inverting) current  and reference it(non inverting in ground)? Is there any advantage of using single supply in this case?


texts: I found a Christmas Village building that has a motor rated at 12V AC 1.5-2W. What power-supply/adapter do I need to power this motor? It seems I can find many 12V adapters, but all would over power the 1.5-2W motor. Am I thinking about this wrong? Would a 12V AC 500ma power-supply at 6W be too much for the motor? Thanks.


texts:
I saw couple of h-bridge circuits based on IR2184 driver that have following circuitry connecting driver and transistor:

My circuit will be full h-bridge driver with load 20A 24V DC motor. I have following questions:

What does this gate circuitry do, does it decreases switching time? Do i need this transil, or zener diode connected to mosfets gate, why is it possible for higher voltage to appear at the gate, is it because of the load? Do i need external reverse diode connected to mosfet when internal diode is sufficient as i think(IRFB4310PbF).


texts:
I speculate this is just barely an EE question, but I'll risk it anyway:

I'm replacing a set of 175C 10A thermal fuses (with 172C 10A actually).  At this temperature / current range, do we need special high-temp crimps or will any ol' ebay copper crimps do?

EDIT: Good comments, some clarifications:

application is an electric single-burner mini stovetop
stovetop wire insulation is in excellent shape and will shroud crimps
crimp material suggestions welcome and appreciated


texts: Do all microcontrollers from one family have the same processor core?

texts:
When we say “family” in the context of a micro-controller do we mean all the micro-controller models under the same family name share exactly the same processor core?

For example ATmega128, ATtiny12 and ATmega16 are all in the same family namely Atmel’s AVR 8 bit family. Can we then say then the thing makes them the same family is their CPU and that is exactly the same?

Do AVR 8 bit and AVR 32 bit families have different processors?


texts: Do I need to connect anything to LCD VGL and VGH pins?

texts:
I'm trying to drive a ER-TFT070-6 LCD using the built in controller in the STM32H7A3ZIT6.
I'm in the process of hooking up the signals between the MCU and LCD, and I'm not sure what to do with the VGH and VGL. I've been using a smaller LCD for my previous designs and it didn't have these pins.
The lcd uses a EK79001 driver.
On a probably related note, I'm not sure what the AVDD and and VCOM pins are for either.
I found an App Note for using the LCD controller, but it doesn't mention these signals.
I found another question that seems to suggest that I need a part like the TPS65160 to supply various voltages needed by the lcd? Is that correct? The EK79001 datasheet shows an external charge pump circuit, I'm thinking that could be present in the LCD assembly? the driving signals are not provided on the LCD connector so I couldn't replicate the circuit on my PCB.
I'm designing the boards on paper right now, I don't actually have the parts on hand.


texts:
I made a circuit with some components (arduino, wifi board, ultrasonic sensor, sound sensor, light sensor, temperature sensor, humidity sensor, some leds and other components) on a breadboard.

The whole circuit is 5V.
The whole circuit drains about 100mA during normal operations and up to 350mA during wifi communication.

Now I'm designing the final PCB.

My question is, which is better?

1) 5V 1A power supply (like smartphones charger)

2) 9V 1A power supply and a voltage regulator on pcb to get 5V (i was thinkg LM317T)

EDIT:
i'm asking this question because with my 5V 1A power supply i actually measure about 4.4V when the circuit is ON (probably due to voltage drops in the breadboard) and I don't know if this could damage the circuit (arduino and wifi board).
I think that with a voltage regulator i will have a clean 5V, but this requires me to buy a 9V adapter and add the LM317, that could add some heat to the circuit.

I don't care much about cost, size and power loss, but i really need reliability


texts: AC Switching Relay isolation with Optocoupler

texts:
I am trying to do a schematic to switch a relay using my MCU. MCU GPIO works at 3.3V. I have come across the following schematic, but unable to calculate proper CTR and thus the value of Base Resistance of Q2.

The Forward Current Vs. CTR graph shows a CTR of 1 at 10mA (Vce 5V)

But I don't see the actually percentage of CTR in the Characeteristic table. The table has listed all the CTR at Vce 10V.

Please help.


texts: Phased array spectrophotometer for coherent and incoherent visible light

texts: What is the principle of operation for a phased array spectrophotometer for coherent and incoherent visible light? I read this recent article about: http://www.laserfocusworld.com/articles/print/volume-51/issue-10/features/lidar-lidar-nears-ubiquity-as-miniature-systems-proliferate.html.


texts: AD7147-1 CDC Conversion Complete Interrupt

texts:
I have three stages connected, Stage0, Stage1, and Stage2. So I want to enable the interrupt after Stage2.

So I write,

STAGE_LOW_INT_ENABLE  (Address 0x005) = 0b0000000000000000

STAGE_HIGH_INT_ENABLE  (Address 0x006) = 0b0000000000000000

STAGE_COMPLETE_INT_ENABLE (Address 0x007) = 0b0000000000000100

Then I read the STAGE_COMPLETE_INT_STATUS Register (Address 0x00A) by my read function.

When I read the STAGE_COMPLETE_INT_STATUS Register (Address 0x00A), it doesn;t print 0b0000000000000100.

Instead sometimes it prints 0b0000000000000111, sometimes 0b0000000000000101, sometimes 0b0000000000000110. But never prints 0b0000000000000100.

So I want to know how can I read the STAGE_COMPLETE_INT_STATUS Register (Address 0x00A) and asserts interrupt when all three conversion stages are complete and my microcontroller will read data from the ADC through I2C.

Thanks


texts: How do you get a short pulse out of a sustained high?

texts:
I am trying to get a half-second pulse out of a long/permanent high pulse. I am still new to electronics and think a capacitor would be involved?

I want to use CMOS logic level.
Accuracy is not too much of a problem, it is only going to be used to activate a monostable.
The voltage I am working with is 15V.

Thanks in advance


texts: Isolated Power Supplies for Inverter Gate Drivers

texts:
I am using a 3-Phase IPM IGBT Inverter Module in motor driver. This module has built-in gate drivers which require 4 Isolated power supplies for their operation. In all I have to design 5 Isolated Power Supplies as shown in the attached drawing.

My input is 2-Phases (380V AC) and the output will be x5 regulators 7815. All 5 outputs will have isolated GND from each other. Max current from each output is less than 500 mA.

If cost is the main factor then how can this be achieved? Should I wound 1 big 50 Hz step-down transformer (380 VAC to 24 VAC) with 5 separate secondary windings or is there any better design technique than this?

The IGBT module is following:


texts: Discharging a capacitor with an analog switch

texts:
I'm designing an op amp integrator with a 100nF capacitor, and need to include a logic level reset/discharge option. I would like to use the DG467 analog switch due to its low cost and small package, however I am concerned about the current rating and on resistance.

Worst-case: the capacitor has the full 10V supply voltage across its terminals (this would only happen in a fault condition), the reset switch is turned on. According to LTspice, the capacitor would discharge in ~10μs, assuming that the switch has a 10Ω on resistance. This will produce a 1A pulse, 10x the "absolute maximum rating" (100mA for 1ms pulsed with a 10% duty cycle).

My question: is a fast (i.e. less than 10μs) 1A pulse likely to destroy the switch? Is it necessary to add a 100Ω series resistance in order to keep the current less than 100mA, and thus increasing the discharge time to 100μs?


texts: PWM dimmed led floor lamp: can it cause eye strain?

texts:
I have a floor lamp (standing lamp which spreads light via the ceiling). It uses LEDs and it's dimmable. When I capture the light with a camera I can clearly see oscillations.

It is known that PWM-dimmed monitors can cause eye strain: https://www.flatpanelshd.com/focus.php?subaction=showfull&id=1362457985.

My question is: can a floor lamp which emits PMW-dimmed light also cause eye strain?


texts: Designing a special 4-bit counter with flip flops

texts:
This is a normal design of 4-bit counter using D flip-flops

The outputs Q0 to Q3 are connected to diodes. I want to modify this counter in such a way that it follows the following counting sequence and that it could be set back to 9 asynchronously (maybe through the Reset and Preset inputs of the flip-flops?) anytime.

Any help would be much appreciated, thank you.


texts:
I need to split the power from an AC/DC converter to two devices. The converter I have takes an AC input of 100 to 240V and outputs 48VDC and 30W power. I have one device that needs 48V and 30W and another that needs between 3 and 5V and can't exceed 15mA.

Is it possible to reach the requirements of both devices, and if so, what would the circuit look like?
If the above is not possible, I can lower the requirements for the first device, but I still don’t know what the circuit would need to look like. Any help?


texts: Graph of a circuit comprising coupled inductors

texts:
In case an arbitrary circuit contains coupled inductors, the system impedance (conductance) matrix is not diagonal. Is there a way to relate such a matrix to adjacency/incidence/Laplacian matrix of the circuit graph?

Also, is it possible to adjust the circuit graph in case inductors are coupled?

In the exemplary circuit labeled with A, where Minc denotes the incidence matrix, one can set the Kirchhoff voltage law for every branch as

\begin{equation*}
M_\mathrm{inc}
\begin{bmatrix}
V_\mathrm{A} \\
V_\mathrm{B} \\
V_\mathrm{C}
\end{bmatrix}=
-\begin{bmatrix}
u_\mathrm{A} \\
u_\mathrm{B} \\
u_\mathrm{C}
\end{bmatrix}
+ Z_\mathrm{br} \begin{bmatrix}
i_\mathrm{A} \\
i_\mathrm{B} \\
i_\mathrm{C}
\end{bmatrix}
\end{equation*}

However, in the circuit from (b), impedance matrix needs to be established as

\begin{equation*}
\begin{bmatrix}
Z_\mathrm{br}
\end{bmatrix}=
\begin{bmatrix}
L_\mathrm{s} & L_\mathrm{m} & L_\mathrm{m} \\
L_\mathrm{m} & L_\mathrm{s} & L_\mathrm{m} \\
L_\mathrm{m} & L_\mathrm{m} & L_\mathrm{s} \\
\end{bmatrix}
\end{equation*}

It is obvious that the branch currents are equal, which diagonalizes the matrix Zbr. However, how to show this using adjacency/incidence/Laplacian matrix (or any other matrix)??

Thanks!


texts: Measuring internal resistance of ammeter with ohmmeter

texts:
I have two TENMA 72-10415. One is set to measure ohm and the other to µA I am trying to measure the resistance between the 10A_MAX <-> COM and mAµA <-> COM.
Measuring between 10A_MAX <-> COM I get as I expect 0.8 ohm and 0A.
However when I measure between mAµA <-> COM I get 1 kohm and 118µA on the ammeter.
I want to measure the current output of my device with a load of 1 kohm. Does this mean the I can simply load my circuit with the ammeter or is something completely wrong with my multimeter?


texts:
Why in the world do people reduce functionality of software when they create a new revision? And why can't people out that two clicks takes more time than one, they've hidden all the buttons in Altium 19

Anyway, I'm looking for this button. I need it for my PCB layout workflow. Usually I'd highlight components in the schematic, then group them. I absolutley hate the rooms feature of altium. There hast to be a better way to duplicate circuits. Anyway...

Where is the arrange components inside area button in Altium 19?

Or how can I group selected components?

Looks like this in older versions:


texts:
I am struggling to put my Timer5 working properly. I think I have enabled all the registers but the interrupt never occurs. I already put a break point inside in the FingerprintRun() in the asm("nop") sentence and I found the TMR5 never goes above 0x0000.

void __ISR(_TIMER_5_VECTOR,IPL4) _T5Interrupt(void)
{
    T5CONbits.ON = 0;
    TMR5 = 0;
    IFS0bits.T5IF = 0;
    UART_TX = 0;
    char x = 'b';
    UARTFingerprintWriteChar( x );
}

void initTIMER5( void ){
    __asm__("EI");
    INTConfigureSystem(INT_SYSTEM_CONFIG_MULT_VECTOR); //configure multi vector
    INTEnableSystemMultiVectoredInt(); //enable interrupts

    T5CONbits.TON = 0;

    T5CONbits.TGATE = 0;
    T5CONbits.SIDL = 0;
    T5CONbits.TCKPS = 0;// 0b111;1:256 prescale value
    TMR5 = 0;
    PR5=0xD0;
    IFS0bits.T5IF = 0; // Clear timer interrupt flag
    IPC5bits.T5IP = 4; // Setting Timer 5 priority to level 4 of 7
    IPC5bits.T5IS = 1; // setting timer 5 sub priority to level 1 of 3

    IEC0bits.T5IE = 1; // Enable timer interrupts
    T5CONbits.TON = 1;
}

void main() {
    initTIMER5();
    asm("nop");
    while(1);
}

Am I missing something?


texts:
Consider:

Here is the schematic I'm trying to work around. My major question is about the LED bar graph I want to use, on the right side; does it need resistors?

I saw three different versions of this microcontroller use ... sometimes with, sometimes without, and the datasheet did not really help. On this point, and it also displays an example of use without a resistor.

Bonus question: Is there something wrong in this?


texts: Why in the Thevenin Theorem do we have to "turn off" independent sources to find Thevenin resistance

texts:
In my basic circuits course we learned a handy circuit analysis technique so that we can simplify a linear circuit to it's equivalent voltage source and resistance.

When looking for the Thevenin resistance I wad told to turn off all independent sources.

Why do we do this (proof wise).

Also why don't we turn off dependent sources too?


texts:
In Verilog, I can use an always block and make it trigger on a positive or negative edge.

Is it possible to trigger the block on both the positive and negative edge, and thus have it basically clocked at twice the rate?

If so, does it incur a resource penalty? Does the compiler need to duplicate the circuit, and generate one that triggers on the positive edge, and one that triggers on the negative?


texts:
Mayby, Sorry for a basic question.

When measuring CT working okay in maintenance, somebody say that the resistance of 0 & (+Vc) and 0 & (-Vc) should have similar values.

Buu, I wonder why these two resistance should be similar to. Also, though using multimeter is simple, is there any other way to check it?


texts: Connect multiple source pins together to power signal in Eaglesoft

texts:
According to PCB shown below, I have a bunch of MOSFETs with HSOF package with 7 pins of source for each and failed to connect EVERY pin to the connector. In other words, when routing the source signal to their destination which is the connector, only one of the pins connects and the others were left unrouted.
The other question is when drawing a polygon with the same signal name, the connection between polygon and DIP pin is too weak to carry high current signals. Is there any option in Eaglesoft to make these kinds of connections strong enough for high current purposes?


texts:
I am working on a Embedded Device using Linux operating System. The device is having a local database for storing sensor information and motor state. This device will be used for controlling a motor and getting some sensor data.

I made a node.js based webserver on this device and made some GET API's for getting the data and controlling the motor also. ( On Local LAN ).

I have to control more number of device using cloud
And also I am having a Server with Linux Operating System. (PC).

Now My Question is:
How to Control All my devices connected on local lan with internet connectivity,
from my Linux Server individually.

I mean, my Linux Server is not aware of my deices's IP and even my devie is not directly accessed from Internet.( because Routing is difficult ).

I need suggestions......Please help me.


texts: How to design a small solar panel and the respective li-ion battery charger IC?

texts:
I'm designing a small solar charger with these characteristics:

Solar panel with 19% monocrystalline cells

Voc = 7,50V
Vmp = 6,00V (Voc -20%)
Isc = 1,07A
Wp = 6,42W

IC

Microchip MCP73871 linear 1A lipoly/li-on charger with VPPC capabilities (input voltage regulation loop)

Battery

Li-ion 3,7V 6600mAh 24,42Wh

-

This configuration works fine, but I decided to move to SunPower cells because the solar panels fabrication, when it's needed to cut the cells, in China is made better. Mainly, due to the fact that Sunpower cells have the "back-contact" technology.
So, given that the Sunpower cells are more efficient (23%), the solar panel will output more total watts, that an IC such as MCP73871 will actually waste because of its 1A current limit.

SunPower solar panel

Voc = 7,125V
Vp = 6,10V
Vmp = 5,7V
Isc = 1,35A ◁◁◁
Wp = ~8,25W

So, I moved my attention to another IC, this time LT3652 (rated 2A). At a first glance it looked fine but then I discovered that it didn't work with a 6V solar panel. It has a VIN_START value of at least 7,50V to start the IC, after that the actual normal nominal operation voltage can be 5,95V.

A solution to this problem could be to cut the SunPower cells smaller to get an higher voltage in the same surface, given that this IC is actually a buck-converter. But someone told me I could really lose efficiency because of the big voltage difference with the input and the battery.

Or perhaps the solution could be to use a different approach with another IC. For example, the ST SPV1040 is a very cool chip with a MPPT perturb and observe embedded algorithm and it looks simple to design. It's designed as a boost converter, so almost any low voltage solar input source is desirable.
My idea could be to use two uncut Sunpower cells to reach 1,22V. To build a  panel with 2 full cells of 125mm x 125mm should be much easier to design and to fabricate, because it has no waste and there's no need to cut the cells. I will boost this voltage to charge the li-ion battery pack. However I can't understand yet how much current this IC can handle and if it's capable alone of a li-ion charging profile.

Within SPV1040's datasheet I found ILx, a value for the current limit.

Is ILx referred to the also called "switch current" of the inductor?

This project has a limited space available for the solar panel surface, so the whole design could be more complicated. I'm talking about 257mm x 175mm.

The very ultimate goal for this charger is to harvest the most possible amount of watts/time, but any solar-specialized technology such as an active MPPT should be taken into account without to fall in an excessive electric circuit complexity, because I'm not an engineer.

Any effort with this question will be very appreciated. Thank you.


texts: Is my simple atmega2560 based product exempt from EMC testing?

texts:
I have designed a product that is essentially a USB HID device for a computer game. It consists of several on off switches and 5v servos run by an atmega2560, all sealed and enclosed in a plastic case. From everything I have read I believe it might be exempt from needing certification, but I would greatly appreciate a second opinion; I'm simply a hobbyist trying to decide the feasability of taking this product to market.

Thanks.


texts: Does using voltage regulator in power supply further reduces the rippling?

texts:
I want to build a 12 V DC power supply. Which one is a better approach?

If I have a step down transformer 220/12 volt and after doing its full wave rectification and smoothing its wave using capacitor, place the load in parallel to the capacitor.

or

I should rather get a 220/15 volt transformer and after doing its full wave rectification and using smoothing capacitor i should use a 7812 voltage regulator at the rectified output along with capacitors recommended to use with voltage regulator? and after doing all that I should place my load to the output of voltage regulator?

Because I heard that voltage regulators reduces the rippling. Is it true?


texts:
I'm trying to build a circuit that balance each cells from lipo battery by discharging them until all of the higher voltage cells are the same voltage as the cell lowest in voltage. Most of the time around 3.8V.

Arduino will be used to monitor the voltage of each cell and to control the mosfets. My electronics knowledge is near to nothing, so I would be glad if someone can help me verify if the circuit below would work.

Will be using a 1Ω 20W clay resistors to discharge each cells, with 1Ω resistance, the highest it would discharge is 4.2A (Max voltage of a lipo would be 4.2V), around 18W at 4.2V.

Mosfets I'm having in mind is FQP30N06L or CEP6030L, both a logic level mosfet, which doesn't matter at the moment until I can figure out whether the circuit would work.


texts:
enter image description hereI am restoring my Sansui AU 6600 Amplifier.

I have taken out all old electrolytic capacitors, and my question is. From the part list for F 2092 capacitors C05 and C06 (10 μF) are listed as BP capacitors and looking at the board diagram I can see that the two capacitor do not have the plus sign, and that is ok. But what I do not understand is that in the schematics, capacitors C15 and C16 (3.3 μF) do not have a plus sign, but in the part list these two are not listed as bipolar capacitors.

Could you please clarify?


texts: phased array beam width spread as beam scans off boresite

texts: What is the approximate phased array beam width spread  as beam scans off bore site? Assume nominal scan space of 120 deg Azimuth by 90 deg Elevation, ie +/- 60 by +/- 45. Array elements are all uniform, and uniformly spaced.


texts: How can there be 8 pole trifasic motors? Shouldn't poles be a multiple of 6?

texts: How can there be trifasic motors with a number of poles non being a multiple of 6? I'd imagine poles in such motors would be 6 or 12 etc.


texts: How to convert 12V 3A Car battery to 5V 1A?

texts:
I want to build a GPS tracker for car for which I need a 5V 1A to power my circuit. The power source being Car battery of 12V 3A, what should I use to get my desired voltage and current?

There will be shrax, current and voltage spikes too. What could be best solution for me to overcome all these and get a constant supply?


texts: shunt capacitance the same as stray capacitance?

texts:
I need a crystal for my project and I found this crystal:
https://mouser.com/ProductDetail/TXC-Corporation/9C-16000MAAJ-T?qs=sGAEpiMZZMsBj6bBr9Q9aWUu9Vmt5DeozjX1gZsyHq8%3D

To calculate the two capacitances for the crystal i used this equation:
CL = (C1 * C2) / (C1 + C2) + Cstray

But the datasheet only giving Cshunt. Is it the same as Cstray?
After calculating with Cshunt for Cstray I come to a value of 22pF.


texts:
When developing software, it's recommended not to reinvent the wheel but to use battle tested libraries e.g. for sorting or proven design patterns like the GoF.

However when it comes to electrical engineering I'm unaware of such libraries. I have bought Circuit pattern trading cards however a friend of mine told me those implementations are not ideal.

Therefore I'm asking: where to find proven circuit design patterns and higher level libraries for electrical engineering tasks?


texts: Non inverting DC-DC converter that makes fix 4V from a decreasing voltage from 4,2V to 2,8V?

texts:
Is it possible to make a a non inverting DC-DC converter that makes a fix 4V from a Li-ion battery's voltage. I need about 1,5A.
The input voltage starts from 4,2V and decreasing to 2,8V as the battery discharging.
Could you recommend an IC or a chematic that has only SMD parts?

Thank you!


texts:
Given this function F(A,B,C,D) = Product-M(4,8,9,11,12) . D(2,3,6,7,10,14)

I know how to get a simplified SOP expression using K-map. However, I'm not sure about simplifying this function until it is K-map ready.

My attempt:
(F(A,B,C,D))' = Sum-m(0,1,2,3,5,6,7,10,13,14,15) + d(0,1,4,5,8,9,11,12,13,15)

There are overlapping minterms. So I don't know how to proceed.


texts:
I am trying to develop a system for bioimpedance measurement.

I will use a frequency equivalent to 50KHz, using this project to support me.

The project uses an instrumentation amplifier. In my city I just found the INA111, but it is a very expensive component, so I decided to make my own instrumentation amplifier using three Op Amps (TL084CN).

I'm using this article to support me Design of an Instrumentation Amplifier - Justin Bauer.

My doubt is:

Since the AD5933 can only read positive voltages, an input of 2.5V is connected into the Vref terminal of instrumentation amplifier (INA118P).
This is done to 'convert' the AC voltage to DC (I think).

How do I do that? If I do not have terminal Vref on my "home Instrumentation Amplifier"?

Sorry, my English is bad (I'm not American), and I'm starting with electronics.


texts: Identifying this part - ALPS 242N Probably a rotary encoder

texts:
This was damaged in shipping.  Looking it over I THINK it's a rotary encoder.
ALPS seems to have forgotten they ever made the part.  Printed on the back is ALPS 242N.  Can't find any specs on it.

UPDATE --
Picked up an ALPS EC12E2420801 (24 Res, 24 Detent).  Wrong part...
Need to measure all the dimensions first next time.  The original part is 16mm wide, the EC12 is <13mm.  Had to go searching through mouser data sheets to find one with the correct dimensions.  Waiting for the new one to show up but it looks like it should work.

Final Update -- Finished!  Picked up a Bournes PEC16-4220F-N0024 (24 PPR, 24 Detent) and it works perfectly.  I don't know if the original had detent or not, but I like the feel of it.


texts: High voltage in electrical grid and Inverter's voltage output range

texts:
I have an 24 V inverter. In the manual i've read that this inverter will bypass the electrical grid voltage in the range 170V-280V.

So with other words , when the electrical grid's voltage goes (for some problem) to 280V , this inverter will output this voltage to my devices connected with it.
On its manual , i've read that this inverter is suitable for all the home/office Devices.
This is very strange , because if the voltage is 280V , appliances like TV,Computers,... will be damaged.

My question is that if I am correct with my logic and these kind of inverters should not be purchased , or i'm wrong and there's something that i don't understand with the inverter's output's range ?

Thank you !


texts: Is there a standard way to number lines on a FFC (Flexible Flat Cable)? In other words, if you see the FFC end from the side with exposed contacts, do you usually start counting from the left or from the right?


texts:
I have a problem with my air conditioner fan not starting. As seen from the schematic below, when I test for voltage between the brown and black wires, I get 0 V (this is the problem). The indoor unit isn't sending the control signal to turn the fan on. The compressor powers on fine though. When I connect the brown and red wires together (since red is giving power fine), the circuit breaker trips, maybe too much inrush current since motor and compressor turn on together?

I then powered the fan separately and it works (fan or capacitor is not faulty).

Could there be a relay or something controlling the fan that's not giving power from brown cable?


texts: How can I stop a solid state relay from latching up?

texts:
I'm trying to use a power relay (PR26MF) to turn on and off a device. The device takes a 9v supply and typically draws ~250mA. I'm finding that the relay turns on just fine, but when I try to turn it off, it won't: it remains latched in the on state.

The datasheet mentions that a snubber circuit across the load may be necessary. I tried adding one (with a ~2ms time constant). It had no effect.

I measured the resistance across the output port of the relay without the load attached; it works as you would expect: ~inf resistance when it's off and low resistance when on. It seems to turn on and off just fine in that setup.

I tried a different load - using the SSR to drive a 5V mechanical relay. The SSR still exhibited the latching behavior.


texts: Can CMRR of a data acquisition input be measured this way?

texts:
I want to check a data acquisition input or overall CMRR of a signal chain roughly by a simple method.

Normally for a daq input CMRR is defined as:

CMRR = 20×log10(Vin/Vout)

where Vin is the common mode voltage Vcm applied at both inputs.

But in practice I hesitate to use the above formula.
It is because when I short the inputs together the Vout is not zero. It has some offset with standard deviation.

So first I short the inputs I obtain x at the output. x represents output voltage and xrms is the rms value of x.

Then I apply purse sinusoid common mode voltage by a function generator. I call the rms value of common mode input as Vrms and the output as a.

Finally I double the pure sinusoid input common mode voltage as 2Vrms and I call the output as b.

I tried to illustrate these by the following drawing:

Is the following approach to estimate the CMRR mathematically correct?:

CMRR = 20xlog10(ΔVcm_rms/ΔVout_rms)

ΔVcm = 2Vrms - Vrms = Vrms

ΔVout_rms = (a_rms - x_rms) - (b_rms - x_rms)

CMRR = 20xlog10[V_rms / (a_rms - b_rms)]

Is the above a valid estimation to verify the claimed CMRR?


texts:
I'm making a 64x64 led matrix project. And I have a lot of componets there: 4096 leds, 1024 resistors, etc. So, when I try to import components from a schematic to a pcb file, Altium hangs and crashes after some time.
How I can solve that?
Thanks


texts: How to implement grounding into this electrical circuit?

texts:
I'm trying to make some tutorials but I have no idea what should I do when I see the term ground (GND). Here is an example:

I want to know how I build the GND part. Where I connect it? Also, if it's a 12 volt application it's very unlikely to kill anyone, is it?


texts: Why need to declare output as a register in verilog

texts:
I am describing a behavioral model of an adder and subtractor with this simple code:

module TOP(
   input SEL,
   input A,
   input B,
   output O
);

always @(SEL)
   case(SEL)
      0:    O = A + B;
      1:    O = A - B;
   endcase

endmodule

However, I get the following error:

Procedural assignment to a non-register O is not permitted, left-hand side should be reg/integer/time/genvar

What is wrong with my behavioral model? Why do I need a register if this functionality can be implemented using combinational logic with primitives? Shouldn't those be just wires on the inputs and the output and a mux that selects the result? None of that needs register.


texts: impact of removing "+:d" in verilog timing section

texts:
I would like to start with the simple example of a flop, and my concentration lies in the specify section , so please ignore the functionality part

module flop (clk,d,o);

...... //Functionality

    specify //Timing section starts

        posedge clk => (q [B]+:d[/B]) = 0;

    endspecify
endmodule

So from the above example, I need to know the exact significance of this  part: +:d. I completely understand that it is the data path.

What would be the impact if i would remove it?

And also backannotation sdf file shows only clk=>q path with delays annotated, but doesn't show any datapath (d) related to that statement. So does that mean it is of no use?


texts: Protected 18650 batteries shut down after I introduce a capacitor to the circuit, why?

texts:
I have a 24V audio amplifier that is powered by 8 packs of 6x protected 18650 batteries connected in series to produce 24V, and then all the packs are connected in parallel.

The amplifier powers a subwoofer and a pair of speakers. The issue was that when subwoofer kicks a deep note, the system just cuts out.

I introduced 2x47000uf capacitors to the circuit in parallel. Problem I have now, is that the batteries just shut down. I tried it with just one capacitor, and then it worked.

I'm guessing the capacitors drain the batteries too fast and they just switch off.

Is there anything I can add to the circuit to prevent this?
Perhaps a resistor? What rating?


texts:
I'm trying to have a LED strip light up when I play my guitar. I'm told I can use a Darlington transistor to switch on and off the LEDs. It would switch using the current from the output of my amp to the speakers. I can not figure out how to wire in the transistor. I've tried a couple of combinations, but the best result I got was very dim LEDs.

Here is some more info on the set up.

Peavey 6505+ guitar amp speaker output = 120W RMS/44V RMS, selectable 4, 8, or 16 ohm

TIP120 NPN transistor = V(CE): 2.0 V(BE): 2.8 I(C) Max: 8.0A Power Dissipation: 80W

Voodoo Lab power supply = 9, 12,or 18V

LED strip = 24" blue flashing LEDs


texts:
Crossposted from Signal Processing stack exchange,
How do radar systems identify friendly targets to avoid AA locks during combat scenarios?
Do friendly planes broadcast a known signal or is something else going on?


texts: What relay do i need to control 220v 16amp motor (water pump)?

texts:
I am new to Arduino and Digital electronics, I have purchased an Arduino UNO, and want to control my water pump from it.

The water pump works on 220V and 15A.

can you guide me on this spec? what relays do i need etc?


texts: Where to solder antennas on 433mhz receiver/send

texts:
I bought some 433mhz senders and receivers and some 433 mhz antennas. Unfortunately I don't know where to solder the antennas.

Where do I solder the antennas to and do I need special solder wire?

Pictures of the sender module

front, back

Pictures of the receiver module

front, back

I tried to solder an antenna onto the sender (into the hole in the bottom left hole in the front picture), this resulted in the signals no longer being sent correctly. I could see that data was sent because the receiver did receive data, but it was not the data i sent with the sender.


texts: Grounding and Signal Integrity of my PCB Layout (ADC, SMPS, SD card, USB)

texts:
I am currently designing a battery monitoring system for an 8 cell lithium battery pack. I originally made the device using a STM32 dev board and breadboard, with an SD card to log data. The system was accurate to +/- 0.01V, but had huge amounts of noise coupled into the ADC readings when there was read/write activity on the SD card.

My board is two layer due to cost constraints. I have managed to maintain pretty much a solid ground plane on the bottom layer. I identified the troublesome components (if not placed correctly) as the switching power supply, SD Card, USB and crystal oscillator. See schematic:

I think my main doubts at the moment are grounding of the board as well as signal integrity for my analog readings. Please could guidance be given on this.

SMPS - I am using a LMR23610 buck converter. I have followed the exact layout given in the datasheet. My only point of confusion was this in the datasheet:

  Have
  a single
  point
  ground
  connection
  to the plane.
  The ground
  connections
  for the feedback
  and enable
  components
  should
  be routed
  to the ground
  plane.
  This
  prevents
  any switched
  or load
  currents
  from
  flowing
  in the analog
  ground
  traces.
  If not properly
  handled,
  poor
  grounding
  can result
  in degraded
  load regulation
  or
  erratic
  output
  voltage
  ripple
  behavior.

I think it means there should be a local ground plane on the top layer around the entire converter, which should only be connected to the PCB wide ground plane at one point (probably through a via). TI has made a sample board for this chip, except they did not follow this advice, rather they had 4 x vias next to each of the grounds of the input and output capacitors. I have done this where applicable for my design. Does my SMPS layout look ok, and is this the correct thing to do?

Power distribution -
I wanted to disturb the bottom layer ground plane as less as possible, which caused quite a bit of difficulty in routing all the traces. In order to easily get the power traces connected I thought to just flood the whole top layer (apart from the SMPS region) with a polygon pour connected to 3.3V (buck converter output). I.e. There are two polygon pours in my top layer - A local GND for the SMPS and 3.3V output from the SMPS. Will this cause me any problems? I could have flooded it with GND instead, but I thought I could do all the GND connections with vias connected directly to my bottom layer.

My final doubt is how I have connected the crystal oscillator. I have created a ground island around the crystal and load capacitors with three vias connecting to the solid ground plane below. Would this be Ok? It is connected like this

Also for the digital signal lines (SD Card, USB), I have made sure to not disturb the ground plane below as I know the return currents will flow below the signal traces. All traces are 10mil width. I have followed all decoupling advice given by ST for this MCU.

Overall, is my layout Ok and there will not be any significant issues such as noisy readings on my ADC? I would readings of accuracy +/- 0.01V as I saw when I built this on a dev board.
Any advice is appreciated as this is the second time I have made a PCB so I am a beginner.

Schematic:

Board:
Top Layer

Top Layer Pour

Bottom Layer


texts: Different square waves from one microcontroller

texts:
I'm doing a project and I need the microcontroller (ATmega328) to do these two things:

Generate a rectangular wave to be filtered and obtain a DC voltage (that varies linearly with the duty cycle)
Generate a square wave (50% duty cycle) with a certain period

The micro will be reading its input pins constantly because the DC voltage and the period needed can change at any moment.

I had thought of doing the first one with PWM and the second one manually setting an output pin or clearing it, counting the period with a timer. However, my question is: can these two things be done together?

I'm thinking that in the code, the microcontroller will be able to follow a routine at a time. So how could I generate these two waves simultaneously (if possible)? If it can be done, could two different PWMs output be used to generate two different signals instead of using a timer and generating the second one manually?


texts: Finding cable impedance, to determine RS485 line termination

texts:
We have some Belden 6341PC cable which will be used with some RS-485 communications equipment, which of I'm learning will need line terminators.  I'm told the resistor values needed should match the characteristic impedance of the cable. The problem is I'm not seeing anything on the datasheet which explicitly mentions the impedance.

I also see that, according to the spec sheet, this cable is rated as being for 'Pro Audio and Intercom Systems', not RS-485 systems.

1) Based on the info on the spec sheet, is there a way to determine which resister termination value should be used?

2) Should I recommend another cable be used instead? The problem is the cable has already been pulled, so we're hoping it'll work without issues.


texts: What is the purpose of the thick blue line in this schematic?

texts: On this schematic for a Z80 computer, there appears to be a thick blue wire connecting some components together. What is it? Googling yields no results: here is the schematic


texts: What happens after a zener diode breaks down?

texts:
I've strapped a 6V zener diode across the 5V/GND rails of my circuit, and I want to know what will happen if my supply were to somehow fail pass 12V straight to the rest of my board.

The zener will definitely fry, but what happens afterwards? Can I say for sure whether the result will be a short or open circuit? Is there any way to ensure I get a short (thereby protecting the other components on the board)? I've learned all about diodes, but no one mentioned what happens after you fry one.


texts: What are the bottom group of diodes for on BLDC motor control circuits?

texts: I'm studying the control circuit for a BLDC motor and I can't figure out what function the diodes serve that I point to in the basic diagram.  What are they for?  At what point in the basic operation of the motor would current need to pass through them and bypass the transistors they are bypassing?


texts: How realistic would charging batteries with inductive power transmission be?

texts: I've read articles on inductive charging and related stuff on Wikipedia and now I wonder - what if I wanted to develop a battery (also a matching charger and the battery compartment) with completely insulated terminals that gives/accepts power via induction as in an inductive charging system? How practical would such battery be?


texts: JLCPCB Preview shows up differently, is that how it is supposed to be?

texts:
I am making a two sided PCB and was going to have it produced using JLCPCB. I made the PCB in Eagle, and this is my first time making it in Eagle (I am not new to PCB making, just the program). I exported the PCB using the default CAM settings. This is how eagle showed my PCB:

and this is how the JLCPCB Gerber View showed it:

It might be a little hard to see, but in the first picture you can see all of the traces, but in the JLCPCB preview only a portion of the traces show mostly on the left side. Is this on purpose, or is there some setting or something I am missing?

EDIT: I was thinking that it may have been rejected by JLCPCB for not passing their DRC, but I doubt that because I used the same set of design rules for the entire board, as well as used Eagle's built in DRC, which returned no errors or warnings.


texts: LED dims when MOSFET switching at a higher speed

texts:
I want to drive LEDs using an Arduino Due and a MOSFET. Below is the circuit I am using, taken from another post: Driving LED strip from microcontroller

I replaced the transistor in the picture with a IRLB8721PbF. Datasheet:https://cdn-shop.adafruit.com/datasheets/irlb8721pbf.pdf

The LED_STRIP is replaced with two LH351B white LEDs connected in series. Datasheet:http://www.samsung.com/global/business/business-images/led/file/product/lighting/201504/Data_Sheet_LH351B_Rev.4.3d.pdf

The forward voltage of the LH351B is approximately 3V, so I am using 6V as my power supply. Basically I want to keep turning the LEDs on and off. I noticed that when I increased the switching frequency, for example 100kHZ, the LEDs were dimmer than what it was when switching at a slower frequency like 1kHz. What could be causing the decrease in brightness?

I believe LED should be able to switch at the nano seconds range? And the MOSFET I am using has rise/fall time at nano seconds as well. Does it have to do with the microcontroller? Below is the code I am using, just a simple digitalWrite using port manipulation:

    PIOD->PIO_SODR = 1<<8; //HIGH on pin 12
    //digitalWrite(12, HIGH);
    delayMicroseconds(10);

    PIOD->PIO_CODR = 1<<8; //LOW on pin 12
    //digitalWrite(12,LOW);
    delayMicroseconds(10);
    }

--EDITED--

full code:

    #include <SPI.h>
    #include <SD.h>
    File dataFile;

    void setup() {
      pinMode(12, OUTPUT);
      Serial.begin(210000);

      if (!SD.begin(10)) {
        Serial.println("Card failed, or not present");
        return;
      }
      Serial.println("card initialized.");
    }

    void loop() {
      int myData_read;
      dataFile = SD.open("DATALOG.dat");
      myData_read = dataFile.read();
      //Serial.println(myData_read);
      for(int i=0; i < 8; i++){
         if((myData_read & (1<<i)) >> i){

            PIOD->PIO_SODR = 1<<8; //HIGH on pin 12
            //digitalWrite(12, HIGH);

            delayMicroseconds(5);
          } else {

            PIOD->PIO_CODR = 1<<8; //LOW on pin 12
            //digitalWrite(12,LOW);
            delayMicroseconds(5);
            }
      }
    dataFile.close();
    }


texts: The relation about FOM and power extraction improvement

texts:
I saw some paper,their comparison is FOM or Power Extraction Improvement(called PEI here),and they are related,PEI=FOM*100,when FOM*100,the PEI value will usually bigger than 100%,take 126% or 425% for example.I want to ask,why will most authors multiply 100 by FOM?why don't they just multiply 10?

The FOM's definition is \$ \frac{P_{o}}{CV^{2}f }\$ ,\$P_o\$ is the output power,and the \$C\$ is \$C_{pz}\$,the capacitor of the PZT;\$V\$=\$V_{PZ(OC)}\$,it is the voltage that PZT produce;\$f\$=\$f_{vib}\$,it is the PZT vibration frequency.

For first picture,i just want to show that the PEI are really bigger than 100% often;For second picture,i just want to let you know what is the meaning  of  \$P_{o}\$


texts: MOSFET failure (RN6020JNZ4) - all pins shorted

texts:
I've made a device to PWM a 20Ω load (a 5kW braking resistor) at 325V DC. PWM frequency is from 2kHz to 500kHz (it's used in a research project).
I first tested the design with a smaller load (a 200W light bulb) and everything was working perfectly. As soon as I tested the same circuit with the 20Ω load all pins of the MOSFET (R6020JNZ4) shorted out and the MOSFET didn't turn off anymore.
I have no clue what happened, I guess a voltage spike coupled into the MOSFET gate? Could I solve this with just a zener diode?
It's strange because I have made a similar circuit with two MOSFETs to chop AC. Same MOSFETs and same setup (gate driver). This is working without any issues. Could somebody give me a hint what happened and how I can solve this issue?

The big metal thing is the braking resistor (20Ω). The white plastic box with the fan is the PWM device.
EDIT: I've measured the gate voltage with an oscilloscope. The load is a 10Kohm power resistor.

EDIT 2: a lot of overshoot when the mosfet turns on. This measurement is done with a 200W light bulb. I don't trust it with the 20ohm load since i'm using my last mosfet.


texts: Understanding multi-contact relay connection diagram

texts: Can someone explain this relay pin drawing to me? It is a Releco C5-A30. Why are the contacts labeled twice, bold and not? Can someone explain how they'd wire this for just a simple N/O switch?


texts:
I want to create an electrical circuit that powers up the computer when a sensor is activated.

This sensor is in parallel with the power switch button.

As far as I understood from reading on different parts of the internet, the power switch button is part of a pull-up resistor circuit that goes into the motherboard as seen here in schema 1.

My idea of the sensor electrical schema that I want to implement is schema 2

But the sensor also needs a +5V supply. I noticed there is a +5V pin on the motherboard where the power button switch connects, but I am not sure if I can use this for my sensor. Is it reserved for something else (speaker?), is the current limited to the motherboard (sensor is going to take up at most a few milliamps) or can I go ahead and use this +5V/GND for my project?

Thanks in advance

Note: I am new to hardware and electrical engineering, so I apologize if the question is a bit silly.

Edit: Thanks for the replies. The sensor is a regular motion sensor (doesn't take more than 200mA if I read it correctly). Also, what's the advantage of using a relay instead of using a transistor for this project, other than separating the current for the 2 circuits. Would one of these relays work?


texts: What transistor or combination of transistors should I use to make a fully controllable AC switch?

texts:
Suppose I want to switch AC. I want to control (allow, prevent, or interrupt) current flow in either direction. SCRs won't do because I want to interrupt current, and I don't recall seeing many IGBTs or FETs that lack an antiparallel diode. Those few I have seen have been low-power and didn't have much of a spec for reverse-blocking.

Are there transistors or other solid-state devices that will do what I want? Or should I perhaps use two IGBTs in series with the directions reversed?

Voltages I'm interested in are on the order of 600VAC. Currents are 10-200 amps. Frequencies are 1-20 kHz.


texts: How to figure out polarity of a polarized capacitor in a circuit

texts:
I've found myself a number of time trying to build a circuit from a schematics that does not provide any polarity indication for caps (probably because the designer used non-polarized caps in the first place), and all I have in my junk box is a bunch of polarized electrolytics with the same value. This typically happens for 1μF's.

The only way I've found so far to figure out how to place the polcap on my circuit is to simulate it with LTSpice and verify what the voltage at the input of the caps looks like.

I was wondering if there was perchance a simple way/trick to do this ?


texts: Binary counter (SN74LV8154) jumps (internal bits seems to flip)

texts:
I am using a "Dual 16-bit binary counter with 3-state output registers" (SN74LV8154) to count input pulses up to 32 bits.

It is working fine most of the time, but some of the bits in the counter seem to flip randomly. The result is reflected in the register, as I see the output value sometimes jump forward and/or backward.

Jumps are persistent (not punctual misreadings) since the value does not jump the other way around right after the issue.
e.g.

0x12fe
0x12ff
0x1200 (should be 0x1300)
0x1201
0x1202 (0x0100 still not on)

The chip allows to read byte by byte with the help of a 4 bit word selector. This is done quite frequently, word by word, and I record a timeseries with the result. I expect the counter to go up by a few increments between reads.

The result is fine most of the time, but it looks like some internal carries are either forgotten or doubled.

Here are a few examples:

|----------------------+------------------------+-------------|
| Before               | After                  | Jump        |
|                      | (Expected)             |             |
|----------------------+------------------------+-------------|
| 0b010011000011111111 |  0b010011001000000000  | 0b100000000 |
|                      | (0b010011000100000000) |             |
| 0b110001000001111111 |  0b110001000000000000  | -0b10000000 |
|                      | (0b110001000010000000) |             |
| 0b111100101011111111 |  0b111100110000000000  | 0b100000000 |
|                      | (0b111100101100000000) |             |
|----------------------+------------------------+-------------|

I also saw jumps by +/- 16, +/- 32, +/-65536, so I guess the issue is not related to the word size.

Any help on how to investigate this would be much appreciated.

Julien


texts: 74HC589 - stock lead times are high, looking for alternative parallel to SPI tri-state chip for ESP8266

texts:
My prototype was going to use 74HC589 as a parallel to SPI interface for ESP8266-07 MCU.  They are in short supply for quick delivery at the moment.

I am asking for suggestions for a similar chip that is suitable to replace it on a 3.3v supply, with a tri-state output, that I might be able to procure more quickly.  It is a new design that is being prototyped on wire-wrap and strip-board, so it does not have to be pin compatible.  A SOP package is OK, but a   DIL/DIP is preferable though.

It is to be used as a 8 bit parallel to SPI input on a bus that has multiple chip select inputs, which is why it needs a tri-state output.  It will be taking inputs from several RA-02 LoRa modules.

I have the 74HC165 in stock, but unless I am reading the data sheet wrong, that does not appear to be tri-state.

This is my first question here, so apologies in advance if I have overlooked the obvious.  My favourite search engine has not yet turned anything suitable up.


texts: How does adding more coils to an AM tuner coil allow it to tune Shortwave?

texts:
I have seen several tutorials about how to turn an AM radio into a Shortwave radio.  They add more coils to the inductor (is that the correct name for the tuning coil?).

Here is one example,

https://www.instructables.com/id/Listen-to-Shortwave-Broadcasts-on-an-AM-Radio/

There are many.  Why does adding more coil make this medium wave AM all of a sudden be able to pick up Shortwave?


texts: STM32F103RB Nucleo - no PLL multiplicator?

texts:
I am using HAL to set up the core clock. When I add RCC_OscInitStruct.PLL.PLLMUL = *any RCC_PLL_MUL*; to my SystemClock_Config function, it appears that HAL_IncTick is never called so it cannot even pass the clock configuration stage.
Now I am able to get only 8 MHz with SYSCLKSource HSI or HSE, and 16 MHz from PLL.
How to get the advertised 72 MHz clock frequency? Here is my init function:

static void SystemClock_Config(void)
{
    RCC_ClkInitTypeDef RCC_ClkInitStruct;
    RCC_OscInitTypeDef RCC_OscInitStruct;

    __HAL_RCC_PWR_CLK_ENABLE();

    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
    RCC_OscInitStruct.HSEState = RCC_HSE_ON;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
//  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
    HAL_RCC_OscConfig(&RCC_OscInitStruct);

    RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
    HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0);
    SystemCoreClockUpdate();

    if (HAL_GetREVID() == 0x1001)
        __HAL_FLASH_PREFETCH_BUFFER_ENABLE();
}


texts:
I want to inject a 2V ac sine wave on a 480V dc bus. to protect my ac signal generator from entering high dc voltage I am going to use capacitor as coupling device. Ac generator also should deliver 15 Amps to bus, the question is does coupling capacitor maintain such big continuous current? if not how can I solve this problem?
Thanks


texts: Is Bluetooth Communication Possible Without Pairing?

texts:
I am working on a device which can wirelessly activate a system "instantly". The first thing which came to mind was to use RFID technology which has the advantage of instant and cheap communication. However, I am interested in using my phone's Bluetooth capabilities to accomplish this task instead.

So my question is, to use Bluetooth communication, is there a way to communicate without pairing? In other words, at a very simplistic level, suppose my Bluetooth receiver is expecting a code "abc123". A Bluetooth device, like a phone, is programmed to constantly transmit this code. Upon receipt of the code, the system commences to do whatever it is supposed to once access is granted. Such a system would remove the pairing barrier, of course, at the cost of security.

So is this concept a possibility? I have little understanding of Bluetooth link protocols at a very technical level, but if someone can give me a lead, I can start learning from that point. Do not consider my limited understanding a constraint.


texts:
The ESP32 data sheet talks about "Motor PWM" vs "LED PWM". The "LED PWM" seems to be a quite straightforward feed-forward circuit, while the "Motor PWM" also has "three fault detection signals, three event-capture signals, and three sync signals".

I'm looking for some explanation what all those extra inputs for "Motor PWM" are for -- which problems do they solve? And then also some example circuitry for how to use them.

It appears to me that I can use the "LED PWM" just find to drive a DC motor via an amplifier suitable for switching inductive loads?


texts:
I have small ESP 12F (ESP8266) module and I can not get it to work. I have used many other modules like Wemos successfully, I can program. I understand that for very basic functionality test the ESP 12F needs to be connected to external 3.3V power source (I use battery) and TX/RX pins to UART-USB converter. Also ground of UART and external power is connected. With this setup and with terminal set to 78440 baud, CR+LF, the ESP 12F should respond to AT commands.

When I issue AT, I get some unknown character in response (⸮). I get this for baud rates from 38400 to 500000. Under 38400 I dont get anything at all, for baud 1000000 I get "Q R" as response and for baud 2000000 I get "Q5R" as response to AT.

So I think that the module can respond, but bits returned are not understood.


texts: Decoupling capacitor for digital potentiometer

texts:
I'm designing a circuit that contains an AD5206 digital potentiometer. I'm using a single 5V supply and the IC has both GND and VDD pins tied to ground.

The data sheet does not make any recommendations for decoupling capacitors and specifies a maximum current draw of only 60 uA (avg. is 12 uA).

Is this current draw so low that decoupling is not required or should I add a 100n decoupling capacitor on the VCC pin?


texts:
I am trying to find out a diagram for pickit1 J3 header, it is not in the manual and I was not able to search it on google. I wonder if somone have it to share here.

Thanks.


texts: Can a 12v base signal be used to switch a v5 device through a transistor?

texts:
I see lots of examples of using low voltage (like from a microprocessor) to switch 12v. I want to do the opposite. Is that okay to do, or should I use a relay? What other components will I need?

The project is supply power to an AtTiny85 when a 10-16v (headlight on a motorcycle) turns on. I will be using a LM2937 (or you can recommend another) to provide power the 3.3v source.


texts: Implementation of Distributed Arithmetic Architecture

texts:
im looking at implementing a distributed arithmetic architecture, but running into some trouble.
From the textbook im looking at  we can rewrite the unsigned convolution of two of two vectors c and x as

where the function, f, is a LUT to give the partial sum. It is used as so in the following example:

However, when it comes to implementation we dont want to use a barrel shifter to shift b times every iteration, so the textbook suggests to do the following:

And I believe that this is implemented as shown in the following circuit

But I fail to understand how this circuit, and the above example would yield the same results. Let us suppose the same scenario as the example i.e.:
c[0] = 2
c[1] = 3
c[2] = 1

and
x[0] = 1
x[1] = 3
x[2] = 7

Then from the circuit we would have the following calculation made when calculating the convolution of x and c (where t is the iteration of the shift adder):
t = 0 : y = (0/2) + 6 = 6
t = 1 : y = (6/2) + 4 = 7
t = 2 : y = (7/2) + 1 = 4

and obviously this answer is wrong, we can see that x * c = (2)(1) + (3)(3) + (1)(7) = 18
So, I ask you, where have I misinterpreted the circuit, what is the problem? Thanks for any help that is given.


texts: I've got an MCU with a 3.3V DAC onboard and I'd like to convert the 0-3.3V signal to a 4-20mA output. Any ideas on how to do this?


texts: Neutral Point Diode Clamped Inverter Switching States

texts: Can someone explain to me the 3 main switching states of the following inverter? I understand the +Vd/2 and 0 output states but I do not understand how there is a (-)VD/2 state unless it has to do with the flyback diodes. 1 is considered actuated. If Sa1 is 1 nSa1 is 0 according to the text this was pulled from for clarification.


texts: Simulation of an asymetric half bridge not working

texts:
I m not able to simulate an asymetric half brige circuit :( I m new on LTspice...

Here is the simulation which is really simple ...

When I simulate it, I am surprised to not have 400V across the inductor at least at the beginning of the turn on MOSFET... The two mosfets are synchrone. At least the gate signals are synchrone...

Thank you very much !


texts: What is the stability of a digital signal processed by a filter with z-transform?

texts:
I have a question from the book FE Electrical and Computer Review Manual by Michael R. Lindeburg page# DE X-1 with its answer as follows:

I tried to solve it as follows:

I don't understand why is it when z = -2 the system is unstable?


texts: Why is voltage gradually increasing from the source of a power MOSFET?

texts:
I have the following set-up:

also note that:

when the motor is running, the voltage on the motor (between source of transistor and gnd) is at around 6V, but it gradually increases. my worry is that it will eventually go over 9V, which is the limit of the motor - and burn it.
the output of the op amp (6 of U3 going to gate) is steady, occasionally fluctuating by 0.01V
the 12V source is actually a bit over 12, let's say 12.6V
to simulate the microcontroller output I've used a L7805 voltage regulator to drop the 12V to 5V (i.e. I plan to control this by a digital signal - preferably non-PWM from a microcontroller - probably 5V output, but 3V3 is also an option)
the motor is http://www.ebay.com/itm/RS-360SH-Pumping-motor-Water-spray-motor-DC-3v-9V-for-water-dispenser-/280928002008 (sorry, but I wasn't able to locate information regarding torque, power consumption in different phases, etc.)

so, any idea why the voltage is gradually increasing on the motor?
besides this, any other suggestions on how to improve the circuit?
furthermore, if I place this setup in parallel twice (i.e. to control two of the same motors with different MCU signals) do you see any other limitation? (note that the source is rated at 12V 5A DC)

EDIT: please note that the resistor between pin 2 of the op-amp and ground is actually 22K

LATER EDIT: as suggested, I tried changing the feedback signal from OPAMP output (aka MOSFET gate) to MOSFET source. This didn't work (not even with resistors to change the value for the feedback) as the response of the motor was not constant, but rather fluctuating (almost stopping, then starting, the stopping, then etc.). I also tried placing the motor between the 12V input and the drain of the MOSFET. This seemed to keep the motor speed constant without the MOSFET heating up, but I was worried that 12V might affect the motor, so I reduced the 12V to 8V using an LM7808, resulting in 7.5V on the motor. This is a solution that keeps the motor running with constant speed, the MOSFET doesn't heat, but, of course, the LM7808 heats up so much that after some time the motor will stop (but after it cools down it works again). I guess that in this case, the only solution would be heatsinking the LM7808 and probably using a PWM signal with fill factor less than 100%. Please confirm this and, in case there is any, tell me how I could further improve this issue (considering that I might not use a PWM signal, but rather that 5V continuous). Thank you.


texts: Earthing terminal detection and indication

texts:
I have developed one instrument and for safety purpose. I want to ensure that machine start only when earthing terminal properly connected to machine and voltage between earth and neutral terminal are less than 10V.

I have search on internet but I can't find any method or circuit that detect that earthing terminal connected with machine and is proper.

If any one have idea or circuit than its great help


texts: Why can't a power supply supply low current?

texts:
I've just read this article and don't quite understand how a power supply can't supply such a low current. I was always under the impression a power supply could supply anything up to its rating, but didn't have a lower limit.

So why would they need to be redesigned?


texts:
I am studying this circuit in my course:

AB is opened, E1 = E5 = 10V, E4 = 40V, R1 = 2 Ohm, R2 = 4 Ohm, R3 = 6 Ohm, R6 = 6 Ohm
I want to write KVL for the Loop 1, what I do usually is defining the voltage drops polarity across each element (resistors in this circuit) but here I have many voltage sources.
Now the question that confused me is: How do I define the voltage drops polarity?
According to an origin voltage source (The highest one, or the one the problem is referring to)? Or I just define the polarity of each element according to its branch and its source separately?
Thank you very much in advance.


texts:
I measured the capacitance between to 100m cables to 10nF with a calibrated LCR meter. Both of the cables are inside a bigger one:

The black part is the isolation. Brown part is the copper itself.
I also tried to calculate the capacitance with this below formula but I get a value of 1.5nF. The epsilon_r of the cable isolation is 2 so total electric permittivity is 2 * 8.8542*10^(-12). I used 100m for l. a = r = 0.7mm.
Is my formula wrong? What am I not considering here?


texts: Where does the inductor energy go in a buck converter when the load is suddenly disconnected?

texts:
It is known that inductors resist a change in current. So, my question is that in a buck converter, what prevents the output voltage from going all the way up due to inductor resisting a current change when there is a load transient? For example, when you go from 3A to 0A. I understand there is some voltage regulation going on, but the inductor still has to discharge all those energy right?
Edit:
An additional question question. Right now, I see that the main functions of the output capactiors are:

supply current when load increase to prevent voltage undershoot

takes energy when load decreases to prevent voltage overshoot

filters the AC output voltage ripple due switching

Did I miss anything? I am trying to put all the parts in a switching regulator together.
Thanks


texts:
1.Does the current flow through the capacitor when (a) it's not charged, (b) it's partially charged, (c) it's fully charged ? How does the flow changes in time (ex.: exponentially, logarithmically, linearly, etc.)?

2.If you charge a 16V capacitor from a 9V battery and then you disconnect the battery, what will be the capacitor voltage? 16 or 9?


texts:
Is there any IC that can be use to convert 9 bit binary code to seven segment display?
EX:
100101100->300
  I want to display 300 in seven segment display when 100101100 binary code applied to input.I want to do this only using ICs not using microcontrollers.


texts: why electrons don't stop moving after passing load resistance

texts: If an electron does work to pass a circuit component (load resistance), why don't they eventually stop moving after passing load resistance and transferring all of its energy


texts: What do these labels mean in the context of VGA timings?

texts:
This is the image provided with the De1 SoC development board. I do not know what some of the abbreviations mean in this context

VGA_R   [7..0]   values for red pixels
VGA_G   [7..0]   values for green pixels
VGA_B   [7..0]   values for blue pixels
VGA_CLK    this I believe is the pixel clock, my screen is 1280x1024 pixels so  108MHz
VGA_SYNC_N Do not know what this is
VGA_BLANK_N Do not know what this is

I have done all my timings for HSYNC and VSYNC, but am unsure what signals should go into VGA_SYNC_N and VGA_BLANK_N.

thanks


texts: Eagle can't find a custom part after adding it to the schematic

texts:
I've created a couple of parts and stored them in a library called trackuino.lbr. I followed sparkfun's tutorial. I am able to add the part to my schematic but when I want to edit the part, I right click on the symbol and choose "Open Symbol" or "Open Device" and I get the following error:

Thoughts?

EDIT:
1. I am able to insert the part with the "Add a part" tool
2. I have tried moving my library from my eagle folder to another directory and adding that directory to the library path. Same issue here, I can add the part but right clicking and choosing "open device" or "Open Symbol" results in the above error.
3. I'm not sure what the "or export drawing libraries first!" part of the error message means?
4. I am running eagle 6.5.0 Light on Linux Lint 15 like Ubuntu 13.04


texts:
I am using STM32F030F4P6 MCU for a project. This MCU has no Vref+ pin and using VDDA pin for A/D conversions, PLL etc. While prototyping the circuit that I am going to use on my project, I shorted VDDA and VDD pins together with 10uF and 100nF capacitors to the ground. I am giving exact 3.3V to these pins with an DC power supply.

ADC will be reading voltage with max amplitude of 16.8V. Therefore I've used 10k / 2k voltage divider, to bring this voltage to logic level. Since I will be reading mostly DC values, I've set the sampling time to highest possible which is 239.5 adc clock cycle - 17.1 microseconds.

The problem is values that I read are way different than voltages I measure with multimeter. For example, ADC is reading ~2.8V when I measure 2.87V.

As you know these MCUs have Vref built-in which you can read through ADC_IN17. When I try to use this to calibrate my ADC, this time measured voltage is lower than read voltage. For example, read voltage is 2.8V when I measure 2.72V.

ADC resolution is 12 bit and ADC accuracy table is shown below.


texts:
I am looking for a VFD. The motor has following specifications:Motor nameplate
YE2-1329-4 and JB/T11707-2013
5.5 kW, 400V, Δ, 11.3 A ,
50Hz,   CosΘ 0.82,  IP 55,  1460 rpm,   87.7.
Is above motor compatible with VFD? Motor will be used with a conveyor belt at variable speed.
Thanks


texts:
I want to do one 'universal' or 'multiprotocol'-capable IO block and currently thinking of using 74LVC1T45 level translator to do the communication between two different voltage leveled systems.

I would want to be able to support UART, I2C and any other custom serial that works in a similar manner. So the B side can be push-pull, open drain, with and without pull-ups/-downs...

The hard part to grasp is how to accommodate a certain open-drain use-case where the interface-d system (B) might NOT have their pull-up mounted...
What should I add/consider when doing the circuit...

How I imagine it, is that for such open-drain use case:

B to A:

A (receiver) side  has to have pull-up(s) enabled. The B side doesn't have a pull-up (for whatever reason).

When B transmits LOW, the A side is also pulled low.
When B wants to transmit High - meaning that B is a float (even though the currently non-existent-pullup should otherwise pull the line high), the 74LVC has no way to pull the A line high ?
Basically, when floating B doesn't go over a threshold of VCCI× 0.65 (so for 1.8V Vih>1.17V), I cannot assume that when B is a float, the A can go to High ?

1) Does, in that case, the B really is isolated from port A ? and I need to add my own pull-up for the B side ?
(as I understand, from A to B direction and open-drain use-case I could get away with the no pull-up on the B side, as when A is high, the B is also pulled high).

or how could I understand it better ?
(I have only found a IBIS model(s) for that part, but no idea how to use that).

Circuit as requested:

simulate this circuit – Schematic created using CircuitLab

2) Aha also, remembered:
In case of bidirectional serial - in that case I2C, the datasheet mentioned that 'the designer must bear in mind that the bus won't get contention when DIR is flipped".
So does this mean that in order to change the DIR, I must first remove either VCCA or VCCB (thus 'disable' the device), change the DIR, enable VCCa or VCCB again, and only then start sending/receiving ?

Assumptions are:

Main MCU is @1.8VccA and the expected maximum interface line is @5VccB
The expected load on the output line B, when trying to pull High, can be max 1k.
(I've read the 74LVC to be specced with 2k load - that's actually good enough for me).
With Output as an open-drain transmitter, the transmitter (B) might not have their pull-up implemented.


texts: I2C Master: How to read with repeated start condition?

texts:
I have a PIC16F18875, on a board where it is configured as I2C master.
7 bit addressing, 100 kHz clock
Several different I2C slave devices are on the bus.
am using MPLAB X IDE with MCC plugin
using the MCC-generated code for interacting with the peripherals
I can read most slave ICs on the board, like some ADCs, and am getting sensible values back
the UCD9090 PMIC, though, is only giving me 0xFF back, no matter which register is attempted to be read
oscilloscope shows good signal integrity
with a RaspberryPi's I²C attached to the same bus, I can read the 9090 just fine
the logic analyzer shows that the slave is transmitting the value to be read back, a nack and the last stop with 36ms (milli) delay after the address-read (see image below)
it is shown that the library code used generates a START+STOP after the address and register# bytes have been sent

using i2c_masterOperation(), i2c_setBuffer() etc

whereas the RaspberryPi logic analyzer readout shows it does the REPEATED START
according to this, some slave devices need a REPEATED START, instead of a STOP+START, to be readable
hence it looks to me that that's the problem

Now, from the MCC generated I2C interface header file, I see no way of telling the code to use the method of repeated-start instead of stop-start. Haven't seen anything configurable on the sparsely populated I2C page in MCC, either.
So, before I go and muck about within autp-generated code...

Is there a way to "properly" do that?
Otherwise, I guess I'll have to dig through their library code and find how to modify it to do what's necessary.

Update:
What I was trying, having been made aware of the state machine altering nature of the setCallbackX functions by brhans, is this:

i2c_error_t i2c_readRegRepeatStart(uint8_t reg, void* data, uint8_t size)
{
    i2c_error_t ret;

    __i2c_buf.reg = reg;
    i2c_setBuffer(&__i2c_buf.reg, 1);
    i2c_setDataCompleteCallback( i2c_restartRead, 0 );
    ret = i2c_masterOperation(false); // writing the start,addr,reg,restart part
    i2c_setDataCompleteCallback( i2c_returnStop, 0 );
    if (ret == I2C_NOERR)
    {
        i2c_setBuffer(data, size);
        ret = i2c_masterOperation(true); // reading the data bytes
    }
    return (ret);
}

I call this like: i2c_readRegRepeatStart( registerNum, &someUshortVar, 2 ).
This code does produce a sequence on the logic analyzer screen that starts out good:

Start
W, Addr, Ack
W, Data, Ack
Repeat Start -- good, that's what I wanted to see, instead of stop/start
R, Addr, Ack
R, Data, Ack
R, Data, Ack

So far, so good, right? Well, almost. Instead of now a STOP, this is what follows:

R, Data, Ack  (19 times)
R, Data, Nack (once)
Stop
Start
R, Addr, Ack
R, Data, Ack
R, Data, Ack
Stop

I haven't figured out yet what's going on. It seems in principle what's supposed to be done, and I traced down to where the buffer pointer and size are set within the MCC library, and it clearly has the value of 2 (size), then the driver is engaged to perform the I2C operation, and it does that weird stuff.


texts: How can I use 7400-series chips to translate the following 5-bit signals into the desired 8-bit signals?

texts:
How can I turn the following 5-bit signals into the desired 8-bit signals? Using only 7400-series chips.

11111 into 00001111,
01111 into 00000011,
00111 into 00000000,
00011 into 10000011,
00001 into 10001111


texts:
I have several transimpedance amplifiers on my board, and I want to avoid the need for a negative power supply, but I can't see any way around it (except for running the current through a resistor but I dont want to load the circuit like that).

At the moment I've been using negative potential to avoid the need for two op amps per channel, but this is also not desirable, is there any way to have a TIA setup without a negative supply?

Cheers

EDIT: I should elaborate, the elements being read are thermistors. Each thermistor is excited by a buffer, the current through the thermistor is then read out by the TIA.


texts: Measuring sinusoidal frequency using the common LC100-A LC meter

texts:
So I need a Frequency meter for sinusoidal signals. I happen to have this common LC100-A L/C meter that is quite good for a very good range and quite cheap as well.

Assuming it does so by frequencies, somewhere in the process of determining th L or C, it would have to do frequency comparisons. Whether by:

Tuning the internal reference C to determine the L being measured against a fixed frequency (and vice versa), or
By having the internal reference C and L being measured in series and counting the frequency (and vice versa).

So I was wondering if there is a way to "tap" into the frequency comparison so I could add a Frequency Meter capability to this neat little device.

EDIT:

Yes, in scenario (1), the LC meter can't simply "tune" an internal reference L... I dunno maybe a Gyrator?? Making (1) the unlikely implementation. But, it's simply for consideration.

Also, the device has a "frequency mesurement" display function, but this only displays the frequency that it's utilizing to determine the L or C being measured. Hinting even more that it is scenario (2).


texts: Its related to my previous question Modes in waveguides I have a doubt that how are different modes actually generated? I mean in Digital and Analog communication, we studied how we modulate the signal to shift its spectrum. At that point of time (Output of modulator) its only electrical signal right (Please correct me if I'm wrong)? How do we generate EM wave corresponding to this modulated signal? How do we make sure that EM wave is belonging to that specific mode which is desired? What goes on the channel is the EM wave, right or the electrical signal?


texts:
I am working with a stm32f103 and am trying to get the external interrupt done.
My code is:

void delay(unsigned int counts);

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

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);

  GPIO_Led.GPIO_Pin = LED_PIN;
  GPIO_Led.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Led.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_Init(LED_PORT, &GPIO_Led);
  LED_OFF;

  delay(500);

  LED_ON;

  // Enable Clock for AFIOEN
  RCC->APB2ENR |= RCC_APB2ENR_AFIOEN;
  // Enable Clock for IOPBEN
  RCC->APB2ENR |= RCC_APB2ENR_IOPBEN;

  // Set PB1 as input with pullup
  GPIOB->CRL &= ~((1 << 4) | (1 << 5));
  GPIOB->CRL |= (1 << 7);
  GPIOB->CRL &= ~(1 << 6);
  GPIOB->ODR |= (1 << 1);

  // Source input for EXTI1 is PB1
  AFIO->EXTICR[0] |= AFIO_EXTICR1_EXTI1_PB;

  // Interrupt request from Line 1 is not masked => enabled
  EXTI->IMR |= (1 << 1);
  // Rising edge
  EXTI->RTSR |= (1 << 1);

  NVIC_InitTypeDef NVIC_InitStruct;
  // Add IRQ vector to NVIC
  // PB1 is connected to EXTI_Line1, which has EXTI1_IRQn vector
  NVIC_InitStruct.NVIC_IRQChannel = EXTI1_IRQn;
  // Set priority
  NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0x0f;
  // Set sub priority
  NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0x0f;
  // Enable interrupt
  NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStruct);

  delay(500);

  LED_OFF;

  // Infinite loop
  while (1)
  {
    LED_TOGGLE;
    delay(500);
  }
}

//---------------------------------------------------------------------------------------
void delay(unsigned int counts)
{
  volatile unsigned int i = 0, j = 0;

  while (i < counts)
  {
    j = 0;
    while (j < 0x1AFF)
    {
      j++;
    }
    i++;
  }
}

//---------------------------------------------------------------------------------------
void EXTI1_IRQHandler()
{
  /* Make sure that interrupt flag is set */
  if (EXTI_GetITStatus(EXTI_Line1) != RESET)
  {
    LED_TOGGLE;
    /* Clear interrupt flag */
    EXTI_ClearITPendingBit(EXTI_Line1);
  }
}

That is the main part of my code. LED_ON, LED_OFF and LED_TOGGLE are only some defines. They work fine.

The problem is:
If there is a rising edge at pin PB1, the stm32 does not jump to the IRQ subroutine. So the stm32 got stuck.

Does anyone know what is the problem? I don't have any ideas.


texts: Lithium Ion Battery - Testing & Self Discharge

texts: It is suggested and commonly understood that if Li-ion batteries drop below a certain threshold that we consider the cell(s) unstable and untrustworthy with a loss in cell capacity and that increased risk of an internal short circuit. This can be particularly disheartening as when we purchase powerbanks and phones on the uncommon occasion they are supplied within the 0-2V region. Historically I have been using float voltage measurements and monitoring Li-ion battery self-discharge rates to determine good cells from bad. My question is whether this form of testing is a reasonable approach and safe, particularly on cells that were discharged to as far as 0V or say 1.7V? Note I tend to look for a self-discharge of around 20mV (0.02V) within a week or two from a charge. Stepping up state of charge in intervals; 3V then 3.4V then 3.6V before accepting the cell(s). I have observed cells drop by as much as 0.5 to 1V within a month, these cells are discarded appropriately.


texts:
Today I found this tutorial on how to build a battery/solar power supply for an arduino here. The tutorial explains on how to use NIMH or Lithium-Ion batteries for this. Step 4 explains how to use NiMh batteries which is what I prefer. The tutorial explains I have to connect the solar panel to the battery and to put a diode between the positive wire of the battery and the solar panel. Then the tutorial explains that you have to use a power booster to get the voltage up to 5 volts for the arduino.

Now the part which I don't understand. Where do I connect the power booster? It is not visible in the tutorial (only for the Lithium-Ion battery, which uses a differenf circuit). Do I connect it together with the solar panel to the battery? Wouldn't the battery be charged and discharged at the same time then? Could someone explain this to me?


texts: Help understanding electron flow through coupling capacitor

texts:
Experiment 12 from my beginners book Make: More electronics is instructing me to build the following circuit..... I apologize for posting the whole circuit when my question has to do with just a small part of the circuit but I felt that if I didn’t post the whole circuit I would not be able to provide the whole context of my question.

In case it helps with the process of understanding the circuit below, the circuit is supposed to function as a microphone amplifier consisting of a pre-amplifier (LM741) and a power amplifier (LM386):

My question has to do with the 10 microfarad capacitor connected to the output of the LM741. The way I see it is that there are two scenarios occurring in this capacitor.

Scenario 1: When the LM741 output voltage goes from a set value to a more positive value electrons flow into the LM741 energizing the capacitor as show in the image below:

Scenario 2: When the LM741 output voltage goes from a set value to a more negative value electrons flow out of the LM741 de-energizing the capacitor as shown it the image below:

I think I am ok with Scenario 1 since it makes sense in my head (given my current level of understanding) that electrons will happily move to a point of higher potential.

However, Scenario 2 has me very confused because I don’t see how that works. The reasons I say this is because I don’t see where the electrons go as they are being pushed out of the coupling capacitor. The way I see it is that they can’t go to the negative terminal because there is no potential difference to make them want to go that way. So it looks to me like they are pushed through other wires connected to the negative terminal but that would cause all kinds of unexpected issues right?

Could someone please help me get a better grip on what is actually happening with this 10 microfarad capacitor as the output voltage of the LM741 swings up and down?

Thanks.


texts: Modifying Viper06 circuit to get 5 V 300 mA

texts:
I got this evaluation board for testing (datasheet here):

Ratings:

Vout = 5 V

Iout = 160 mA

It uses Viper06 IC at 30 kHz switching frequency (datasheet here).
I tried drawing 200 mA from it and the IC went into drain current limit mode. It was shutting down and restarting after 1 second.

Datasheet has these specs for drain current ratings:

There is a way to limit the max drain current. By default, the limit is set to max. (which is what I need)

The max limit is not high enough for my use case. I need 5 V 300 mA. Is it even possible with this IC (in non-isolated buck converter mode)? What's the smallest change I should do in the board circuit to increase the current to 300 mA?

Here are things I have tried:

Board comes with 680 uH inductor. It fails (goes into overload mode) at 200 mA.

I replaced the inductor with 1 mH 500 mA inductor. It passed at 200 mA and failed at 250 mA.

1.5 mH 430 mA passed at 250 mA and failed at 300 mA.

Increasing inductor appears to be one way of increasing the output current but I am not sure whether this is the most effective way.


texts: NodeMCU-12E - Conflict between I2C and SPI

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I have SPI SD-card module connected to nodeMCU, and it's worked well. Next I try to connect I2C sensor, and it doesn't work. Looks like SPI conflicts with I2C, because when I disconnect SD-card, I2C sensor get worked.

I use Arduino IDE with esp8266 board framework.
The key code:

Adafruit_BME280 bme; // I2C
bme_status = bme.begin(0x76);
...

const int chipSelect = 4; // Don't worked with other values!!!
sd_status = SD.begin(chipSelect);

Another question is why SD card worked only with chipSelect=4?


texts: GSM Data Post Over the GPRS Using GSM Modem

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I'm using GSM Modem To post the data over the GPRS for specific website.

when i'm posting the data using VODAFONE IN (APN: www) Sim card it pos the data in i'm recieved
HTTP 200 ok Response

But in other case when i'm posting the data using AIRTEL IN (APN : airtelgprs.com)

but data is not posted  i'm recieving

HTTP 400 bad request


texts: How much current can lead acid batteries safely supply?

texts: I have a motor I wish to drive with an 18V lead acid battery. The motor can draw quite a lot of current when stalling and I am worried of overdischarging the lead acid battery. Unlike LiPo batteries with have a maximum current rating, the lead acid battery only stated the "initial current", which is used for charging. The label stated not to short the battery. Hence, may I know what/how to find out the safe current to draw? How will the battery fail if I draw too much current (explode/lifespan decreased/?)? Thanks


texts:
Hello everybody I have a question about resistance in Ohm's law, according to the formula "I = U/R" the less resistance you have, the more current you got and accordingly the more power you drain. So I don't get it, is this meaning the more load you got the less power you drain? That's a little counterintuitive, so I need a little advice from you guys to make this clear.
Thank you in advance.

Just to make things clear.

An electrical load is an electrical component or portion of a circuit that consumes (active) electricpower. E.g. solenoid, motor, lightbulb etc.
The stronger load (solenoid), the more wire it has, the more resistance it has.
The higher resistance in circuit, the lower current flow, and the power.


texts: Problem with high-pass filter - signal gets shifted down

texts:
I have a problem where I am passing pulses received from a photo-diode into a high pass RC filter. Circuit shown below.

The pulses are being received at 25Khz. Before the filter, the pulses are measured as expected. After the filter, the signal gets shifted as shown below and only seems to stabilize after around the 10th pulse. I assume that this is due to the RC time constant of the HPF.

This is a problem as I then amplify the signals after by an op-amp with a 0v cut off so I am then left with an inaccurate decaying signal.

The values of the capacitor and resistor in the HPF are selected to have a cut-off frequency of around 1500Hz.

Would anyone have a solution to this problem or some recommendations? It would be greatly appreciated. Can I change the filter in anyways to stop this signal shift? Thanks

The signal-not a great picture but the shift down can be seen.


texts: ADS1115: Protection circuit for ADC input

texts:
I am using an ADS1115 for measuring DC analog voltage in range of 0-10V.(Sensor output range)
I am using thr IC in single ended input configuration and continuous conversion mode with FSR= 6.144  and output data rate of 860sps.
I am using a pull down resistor R14 of 1Mohm to avoid floating condition when the input pin is not connected.
I have selected 1Mohm resistor because the sensor is of resistive  type that's why the 1Mohm doesn't interfere with the sensor output voltage.
The sensor output voltage is given to the input of the first stage buffer which acts as a voltage follower. The output of the buffer is given to the voltage divider for scaling the input voltage from 0V to 10V. After the voltage is scaled it is given as the input to the second stage buffer.The buffer was added so that the voltage divider resistor (R15=R16) doesn't interfere with the RC circuit and change the cutoff frequency of the RC circuit which is 8.6 kHz.  The RC circuit is use as a low pass filter.
The diode D5 is a schottky diode which is used for overvoltage protection as the IC can only handle the input voltage  of  VDD+0.3 (VDD=5V). I used R18 just to model the input impedance of the ADC1115 as 10Mohm (is i have assumed by taking the average of common mode impedance and differential mode impedance.)
I am getting correct output.
Any minimization I can do in the circuit or any suggestions?
ADS1115 datasheet.


texts: Measuring Current in Combination Circuit with a Shunt

texts:
I've done a fair bit of looking/asking around for help with this but I'm struggling to come up with an answer ....

I'd like to measure and record current in a circuit. There is a 12 VDC / 2 A power supply which provides power to two instruments. They draw 75 mA, and 640 mA at 12 V respectively. They're in parallel with the supply, like this:

Instrument 2 is a water pump which operates at a nominal rate of 3 L/min. However, if it gets clogged for some reason, it draws more current in order to try maintain that 3 L/min output.

SO, I would like to be able to measure and log the current supply to these devices. From my research, it appears as though a shunt is a possible option. I would place it just before the negative lead on the power supply, and record the voltage drop across it using an external DAQ device (which measures from -10 to 10 V), much like this:

I guess my questions are:
1) Is this the best way to solve this problem? If not, what would be a better alternative?
2) If it is a good option (or even if it isn't, maybe humour me a bit ....) what "type" of shunt should I get? Is this the right way to wire the shunt. Unfortunately, the instruments themselves cannot be re-configured.

I would be happy to provide more detail as required.


texts: Should I use MLCC or Tantalum capacitors near the board's power input?

texts:
My board consists of a microcontroller, some RF modules (i.e. bluetooth, wifi, etc), and a few other gadgets.

It is powered by a 12V barrel adapter.  I've read conflicting reports whether it's best to use MLCC or tantalum capacitors to bypass the power supply near the board's power input.

I previously thought MLCC's have come a long way and now have made tantalum's nearly obsolete in this regard.

Is there a reason why one may use tantalum 0.1uF and 10uF caps instead of MLCC?  Why?