texts: How do I turn off multiple data connections with a single switch?

texts:
I am pretty new to electronics but so I've been doing a lot of reading and whatnot. I have a question I can't seem to find any information on. I am modding a handheld device (the device in question isn't important) and this involves soldering to several spots on the motherboard which are DAT0, DAT1, Dat2, Dat3, GND, CLK & SMD (these grant access to the internal storage nand chip).
Each of these connections are their own wire (7 wires total) that all lead to an SD Card reader PCB. The problem is, I want to be able to turn on/off all 7 connections using just one switch, because when these wires are soldered to the SD Card reader PCB, the device boots into a special recovery mode, but I only want the device to boot into that recovery mode when a single switch is flipped on. I need a way to break the connection on each wire in between the device's motherboard and the SD Card Reader PCB (and be able to connect them up again using a single switch). I think that would be so cool!
I've considered using a series of small surface mounted solid state relays in parallel, wiring each of the 7 connections through the collector and emitter side of each relay. However, I'm seeing that solid state relays are typically used to close a circuit with a higher voltage, like 60V or something even higher. Are solid state relays ever used for data connections on the collector and emitter side? Would using a solid state relay somehow ruin the flow of data from the device's motherboard to the SD Card reader's PCB? I'm not asking anyone to come up with a schematic or anything, but if there's some other kind of small smd component that would suit this task better, please let me know!
Also, please keep in mind I need these components to be small enough to fit in an area about 4mm high! I would totally use mechanical relays, but those are far too big!
Sorry if this post is confusing, I was too tired to sketch out something, but if that would help I'd be glad to do it as well as answer any other questions you may have. Thank you for taking the time to read!


texts: 6v switch to power something much larger

texts:
I feel like I'm making this more complicated than it has to be. If I have a 6v switch like this one, can I use it to turn on something like a 110v ~26A power supply? The current is far too high for the switch - I know that.

So I figure I should use the switch to control a relay kinda like this that CAN handle the amps. But that would mean converting 110 AC (from the wall) to 6v DC to run through the switch and to the relay which I think is wrong. Wouldn't I need to convert it into a signal somehow?

I'm a software guy with very little EE knowledge. Thanks in advance!


texts:
My goal was to amplify audio signal coming from Raspberry PI's audio jack, so it is louder. I have basically no clue what I am doing, but it seems to work - when I connect the speaker directly to the audio jack, it is very weak, but connecting with transistor makes much louder sound.

Is my circuit correct?

Or am I going to destroy the speaker or even raspi?

How comes there is no GROUND needed in my circuit?

My transistor is CTBC 640
My speaker is 8 ohm, 0.25W


texts: I have two diodes one has an voltage drop of 0.2v while other has a drop of 0.55v in the same circuit. While I use the 0.55v drop diode for freewheeling (35 Amps diode) and the other diode remains in the same circuit. Is it possible for the freewheeling current to flow through diode with lower voltage drop (in5408)


texts:
This is part of a segment of a design I came up with using schmitt triggers as relaxation oscillators.

The picture below shows the 4 possible states of the circuit at any given time.

Basically, the left side toggles between 0V and 3V faster than the right. From this, the voltage across C3 changes at different rates given what 'state' the schmitts are in (0,0...0,3...3,0...3,3). This changes the oscillation rate and hence generates two different tones.

The capacitor voltage moves between 0.478V and 2.054V as thats the upper and lower thresholds the schmitt toggles its output.

Basically what I need to do is find the time taken to charge then discharge, with respect to C. From here I can spreadsheet capacitor values and pick one that generates the frequency I desire.
The (0,0) and the (3,3) states are easy because its a simple RC circuit after you combine the parallel resistors.
The (0,3) and the (3,0) states are harder because as Vc goes up, it opens up a potential voltage drop across the other resistor.

This is the formula I derived to find t with respect to C;

Granted the only difference is the direction the 3V comes from for these 2 harder states, I thought I could just swap what i substitue for R1 and R2 around.
When R1 = 3300ohms, R2 = 560ohms....I can solve it.
But when R1 = 560ohms and R2=3300ohms I get a negetive inside my log and cant get any further.

Is there a better way to be trying to calculate these 2 conditions? How can I work out the (0,3) state?

Thanks for any help.


texts: What do these signs mean in some digital timing diagrams?

texts:
The blue are digital timing diagrams in the below example:

But what do the black signs represent? I see this rarely on some digital timing diagrams.

Another example:


texts:
I've recently set up a small circuit for PH measurement using a BNC PH electrode.
A picture of my circuit can be seen below:

The linear reference REF1 alongside opamp U1A serve to generate a 2.5V buffer voltage so that the voltage generated by the probe will always be in a readable range. I'm also using this as a makeshift guard voltage to minimize leakage losses on the PCB. U1B is simply a unity gain voltage follower who's output is sent to the ADC.

I chose the LMC6482 mainly because of the ultra low input bias current (20fA), as well as the fact that the through hole package allows for better low-leakage routing on the PCB. A picture of my layout can be seen below:

I've kept all tracks, particularly the raw probe voltage, as short as possible, and I've put a guard ring/guard plane around that node as well.

I took most of my design decisions from the following application note from TI: http://www.ti.com/lit/an/snoa529a/snoa529a.pdf

Unfortunately I've been having some problems with the reliability of my circuit. I had to implement a software low-pass filter (a simple 20-sample rolling average filter, a new sample is taken every two seconds) because the output of the circuit was varying (some noise is always expected so this didn't worry me so much). However even with the software filter, my PH readings will tend to slowly drift around. For example, if I put it into a PH 7 calibration solution, it will start out steady, but then vary from 6.5 to 7.5 very slowly, and sometimes it will even deviate by one whole point on the PH scale (it usually returns to normal after a time though). I'm not compensating for temperature at the moment, but the temperature in the lab does not vary much from 22C, and the timescale of these tests is short enough that I doubt temperature variation is the cause.

I've simply been calibrating the circuit using a single calibration point at a PH of 7.0 using the test solution. Is this sufficient for reliable use? If not, is there a way to do multi-point calibration?

Thank you

Edit:
The probe in question is a chinese version of the following:
https://www.e-gizmo.net/oc/kits%20documents/PH%20Sensor%20E-201-C/PH%20Sensor%20E-201-C.pdf

I'm not expecting absolutely stellar performance, I just want to make sure that the measurement stability problems I'm having are not on my end.


texts: PIC18F2550 and DS1307 i2c RTC MPLAB assembly code. Have to loop for seconds,mins,hrs

texts:
PIC18F2550   and DS1307  i2c RTC MPLAB assembly code.

I am using a PIC18f2550 to get time,date,etc from DS1307.

I am able to get the seconds,minutes, hours, etc by repeatly CALLing  GET_TIME with a new Read Address 0 to 6.
I am unable to get all the Parameters sec, min, hrs, etc in one reading as below in Read_Clk.

Could someone tell me what I am doing wrong? Using it as it is only returns "Seconds" in each of the seconds, minutes, hours, etc....  I have posted a picture because of lines offset.

WAIT_PIR_SSPIF:
    BTFSS   PIR1,SSPIF
    GOTO    WAIT_PIR_SSPIF
    RETURN

WRITE_CLK:    ;Write data to slave.; //Write data to I2C bus
    BCF     PIR1,SSPIF
    MOVFF   WRITE_DATA,SSPBUF
CheckWrite:
    BTFSS   PIR1,SSPIF
    GOTO    CheckWrite
    RETURN

GET_TIME:
    CALL     START_CLK
    MOVLW    b'11010000'
    MOVWF    WRITE_DATA
    CALL     WRITE_CLK
    MOVLW    b'00000000'           ;ADDRESS OF TIME TO READ
    MOVWF    WRITE_DATA
    CALL     WRITE_CLK
    CALL     DELAY_2nd
    CALL     RESTART_CLK
    MOVLW    b'11010001'
    MOVWF    WRITE_DATA
    CALL     WRITE_CLK
    BSF      SSPCON2,ACKDT         ;SAME AS "NACK"
    CALL     DELAY_2nd
    CALL     Read_Clk                       ;CALLS READ_CLK
    CALL     STOP_CLK
    CALL     DELAY_2nd
    GOTO     GET_TIME

Read_Clk:             ; //Read data from I2C bus
    BSF     SSPCON2,RCEN
    BCF     PIR1,SSPIF
    CALL    WAIT_PIR_SSPIF
    MOVFF   SSPBUF,SECONDS
    BSF     SSPCON2,ACKEN
    BCF     PIR1,SSPIF
    CALL    WAIT_PIR_SSPIF
    MOVFF   SSPBUF,MINUTES
    BSF     SSPCON2,ACKEN
    BCF     PIR1,SSPIF
    CALL    WAIT_PIR_SSPIF
    MOVFF   SSPBUF,HOURS
    BSF     SSPCON2,ACKEN
    BCF     PIR1,SSPIF
    CALL    WAIT_PIR_SSPIF
    MOVFF   SSPBUF,DAYS
    BSF     SSPCON2,ACKEN
    BCF     PIR1,SSPIF
    CALL    WAIT_PIR_SSPIF
    RETURN

DELAY_2nd:
    MOVLW   b'00000100'
    MOVWF   COUNT_DOWN
DELAY_2:


texts: Amplitude Modulating a simple Laser using an RF transformer

texts:
I know I can modulate a laser using an audio transformer see pic and website below. Pen Laser website

I was wondering if it’s possible to modulate a simple pen laser using RF signals in the RF range of 1Mhz-100Mhz range?

I was thinking of replacing the audio transformer with a RF transformer and using a function generator to generate the RF signal.  Here’s the RF transformer I was looking at. RF Transformer Is this possible?

Would a solar cell connected to an an oscilloscope work as a receiver at such high frequencies see pic? (I would replace the stereo with an oscilloscope)


texts:
I am trying to design a power supply for a 3.3 V / max. 340 mA system.
It should provide the possibility for 5 V-12 V input as well as directly providing 3.3 V. Even though it is not intended to connect both input voltages, the system should not break down in that case (at least it should work again, as soon as only one supply is connected).

My first attempt is using Schottky-Diodes, but this would result in 2.9 V output voltage and not 3.3 V:

simulate this circuit – Schematic created using CircuitLab

Any idea?


texts: How do I get started with electronics/hardware?

texts:
I'm a programmer and mathematician by profession, and I would like to get started in electronics/hardware. I have an Arduino, and I've written some basic programs in it (alarm clock with LCD and speaker, etc.), but I would like to learn more about the actual electronics. What books/tutorials are good for this? I don't mind mathematics (esp. calculus since that I would guess is used a lot in EE). In fact, something with good mathematical treatment is welcomed, but I don't want to shy away from intuitive explanations either. Something in the middle would be good. My knowledge right now is:

How a resistor works
How a capacitor works

and NOTHING ELSE.


texts: RxTx communication with multiple slaves using a RaspberryPi

texts:
I am a programmer trying to build a circuit with limited EE knowledge. With so many options(at least being new to this), just want to make sure I am going down the right path.

What I am trying to build is a master device with a RaspberryPi and many plug and play slaves(relays and sensors with very small amounts of data transfer). Seems like using modbus/rs485/pic/75176(LTC485) would be the best solution.

Consumer device, so component costs matter and an off the shelf product won't work.
The more devices I can connect the better. (My understanding is Modbus can do 250 devices by default, but I can do a double register(16bit) to get 65k tho bandwidth will probably cut that in at least half which is fine)
Slaves can be repeated many times. ie 10 of the same temperature sensors. I'm understanding that I don't necesarily have to define the slave id in modbus and can define it on the fly. Please correct me if I am wrong since I can't ask a consumer to set the ID manually if there is more than 1.
I need the consumer (true end user no corporate) to just plug a device in and have the system recognize what it is and be able to uniquely identify it.
True real time is not needed, a few second delay isn't a big deal.
Everything will be a call from the master to get data from the slave. Nothing originating from the slaves.
Plan on using a standard rj45 cable with a max distance of 100m since that's what they are rated for (cheap simple standard).
Lastly, I do plan on having a wireless option in the future, so if any of it can mesh well, that's a bonus.

I found this example that seems like what I am looking for. Doing my code in c++, but should be easy to convert.
https://docs.google.com/document/d/1YN4BeXw4zrb2dlk9HcTDxd-E5vxNjVN8wcSF4Q86yz0/

Again, I have much to learn, but tired of going down a bunch of wrong paths, so any advice would be great.

Thanks ahead of time.


texts: Find iD1, iD3 and Vo for Vi=3V & Vi=-3V. (Diodes)

texts:
I was just wondering if my solution to the attached question is correct or not?

Thanks!


texts: Checking for a short in a circuit with a large capacitor?

texts:
I'm developing a small testing application for my company that tests various hardware and software functionality.

I do however have a problem developing a simple way to check for short circuits in the system (given a limited knowledge of electronics, I'm mainly a programmer).

The problem I have is that the system has a large capacitor (40 farad) with a fairly low average load (~50mA at 3.8V) where the capacitor may, or may not be previously charged.

Because of the capacitor i cannot simply check for a large current flowing from the power supply because that would probably just be the capacitor being charged.

My idea was to check if the current decreases at an expected rate given the capacitor. I'm afraid I don't know enough about capacitors or electronics in general to be able to accurately predict the capacitor charge and detect such a variation.

I thus would like to ask guidance on how to reliably perform such a check, or if there is any better way to check for a short circuit given a large capacitor. I have a fairly rudimentary knowledge of electronics and don't know much beyond the basics.


texts: How to read Map-Report in FPGA Synthesis Tools

texts:
I have this Map-Report piece product by Lattice Diamond:

...
 Number of SLICEs:  9609 out of 33264 (29%)
    SLICEs(logic/ROM):  8814 out of 26460 (33%)
    SLICEs(logic/ROM/RAM):  795 out of 6804 (12%)
         As RAM:  795 out of 6804 (12%)
         As Logic/ROM:  0 out of 6804 (0%)
....

I already know what means the first line (Number of SLICEs), but I can't figure out what the rest means; can someone explain precisely the difference between SLICEs(logic/ROM) and SLICEs(logic/ROM/RAM)?

I have downloaded dozens of manual, but where can I find more info about all the other report voices?


texts:
I am a novice with LTSpice, and I am attempting to use an HSpice model from Analog Devices.
The component is a comparator (ADCMP601).

Unfortunately it appears that there is only an HSpice model, which I assumed had almost identical syntax to LTSpice.

My issue is that there are multiple instances of: "max=value min=value" (see example below) throughout the .SUBCKT file, which doesn't seem to be legal in LTSpice.

e0 18 0 17 0 4 max=0.3 min=-0.3
e1 20 0 19 0 1 max=0.3 min=-0.3

Is there a way to force max/min values using LTSpice syntax, in a similar manner to the original HSpice form? Or is it pointless trying to do this in LTSpice due to other potential syntax errors?

Thanks in advance!

I've attached the images of the circuit and error log.

Sine to square wave

Error log


texts:
So I'm currently working on a standing LED lamp with WS2812B LEDs. The length will be about 1.2m with 60 LED/m. I'm planning to cover the LEDs with white epoxy to diffuse the light and have a nice finish.

Will heat be a problem when I have the light on for quite some time? Should I add an acrylic glass panel over the LEDs with little air ventilation holes to prevent any overheating which would result in a fire or reduce the lifetime of the LEDs?


texts: Is there a correct way to document RoHS compliance?

texts: I work for a small electrical engineering company. Our products are not presently RoHS, but we're planning to switch over. As best I can tell, this is a matter of ensuring that our individual components are RoHS, and using lead-free solder. But what documents do we need to keep on hand? Do we need a file of letters from each component manufacturer? Or is it enough to glance at Digikey and see a green leaf next to the component name?


texts:
I am currently analysing this circuit

But I ran into some problem since the boost component standalone raises the voltage to 40v the flyback is suppose to bring up the voltage to a further 540v right ?

But from my analysis I found that the boost acts like a buck

And the total voltage output now becomes

140v, which is far from the expected 540 v so could someone help me explain why this occurs ? Thank You :)


texts: What does the input to output ratio for a PLL chip mean?

texts:
For PLL chips, digikey notes the "Ratio - Input:Output". For example, here are two 74HCT4046 ICs:

This TI chip has a "Ratio - Input:Output" of "1:4"
This NXP chip has a "Ratio - Input:Output" of "2:3"

What does this "Ratio - Input:Output" mean?

Why does it vary for different 74HCT4046 ICs? Are not all 74HCT4046 made (more or less) equal?

I've searched both datasheets for the term (or a similar one), and I can't find any explanation. The word "ratio" doesn't appear at all in the TI datasheet. "Ratio" does show up in the NXP datasheet, but it seems to be in a different context.


texts: Connect common ground stereo to a device with different ground for each channel

texts:
I have an old stereo that I want to resurrect and add Bluetooth to it. For that, I bought a Bluetooth module, this one: https://www.aliexpress.com/item/PAM8403-Wireless-Stereo-Audio-Receiver-Module-For-Arduino-Digital-Amplifier-Sound-Loud-Board-Micro-USB-Bluetooth/32668159372.html?spm=a2g0s.9042311.0.0.7b634c4dWucCH7

The problem is when I try to connect it to my stereo. My stereo has a common ground for both the line in and the speakers, while the Bluetooth thing has different grounds for each channel.

I've tried to connect the speakers directly to the bluetooth thing, and it sounds fine, but when I short the grounds the music stops playing.

Is there any way I can connect that to my stereo?


texts: Amplifying analogue audio from an iPhone docking station

texts:
So I have an old iPhone speaker dock that broke after I plugged in the wrong cable and fried the microchips on the circuit board. From it however I salvaged the dock connector itself and a couple speakers. I've wired these together on a proto-board to get the iPhone to recognize that it is docked and play music out of the two speakers. Obviously however the iPhone only outputs audio at a level to play through headphones so it is very quiet. I would like to build a small circuit to amplify this sound with an external power source and I may also get it to charge the phone too eventually. I don't have any idea about handling analogue audio though. I have used OP Amps before in basic projects at school to amplify an LDR but that's all. Could someone please point me in the right direction in terms of which IC to use for this project and how to connect it up?

Presumably all the circuitry that came with the docking station did all this but its fried and looks way over-complicated for what I want to do. Also it would be nice to use a variable resistor to change the volume too at some point.

Thanks in advance.


texts: Transient Current Effects from Independent Charging Circuit

texts:
I've been working to automate a household appliance.  The device is normally controlled by a switch that must constantly be depressed in order for the device to operate.  Instead, I replaced this switch with an NPN transistor that I control via an arduino.

The diagram below shows my setup.  The motor circuit refers to the appliance control circuit which includes its own battery and charging circuit.  I simply removed the switch from this circuit and connected the leads to my control circuit.

In my first attempt, I ran into issues with transients, but I was able to address this by adding the ground.  However, on this third time building the circuit, I am running into transient issues again.  As before, when the arduino digital pin is set to high, the device is properly activated.  However, when it is set to low, the device does not completely turn off.

Is it possible that this is an issue with the appliance control circuit?  How can I make this circuit more robust to transient currents?


texts: Switching coupled inductors in series while one is charged

texts:
I am designing a coil gun and would like to dump some energy from each coil into the next coil before (preferably) dumping its remaining energy back into its storage capacitor.

If I have two coupled coils, with current only flowing in one, and then switch the other one in series with it (common mode) will the current rapidly drop to nearly half (since the magnetic field is already partially established through both coils) or will something else happen?

Producing a voltage spike on the MOSFET that cannot be easily supressed would be quite undesirable, I think the capacitor on the MOSFET is still necessary as the magnetic field still needs to shift a fair bit since the coils are not co-wound. If the current can be brought near equal very quickly this will be very beneficial as the magnetic equilibrium point for the slug will be shifted past the first coil very rapidly and without using the capacitor for the second coil at all.

Here is a basic partial diagram of the concept, the diode is just to prevent a current flowing backwards in the second coil while the first coil charges. The MOSFET would be turned off to switch the second coil in. The coils would be two cylindrical coils placed next to each other coaxially.

EDIT:  MOSFET replaced with switch for clarity

Ok so I have clarified the circuit a little (sorry I just use eagle since I have it open for another project). So what I would like to know is if the switch is closed and there is a fair magnetic field established in L1 what will happen when you open the switch? Will the current in L2 increase very rapidly and roughly proportionally to a decrease in L1 current, or will L2 charge at a pace similar to as if they were not coupled while L1 tries to push its existing current through the small snubber capacitor and destroy the MOSFET.

I am pretty sure it is the former, and I feel like it would be very rapid, but I would like to know from someone who properly knows these things roughly how two adjacent air core inductors will behave in this situation.


texts: can not comiunicate through ask rf module

texts:
I wanted to send data by ardunio through dra886tx(board on the left side )  and receive by another ardunio through dra887rx ; i don't know whats the problem but nothing happen on the receiver board and I'm sure my code are fine because when i replace RF module with actual wire , second arduino receive the signal perfectly ( I'm using virtual wire library programing board )

"sorry for my bad English"


texts: What is the efficient way to perform FFT for large set of Samples?

texts:
I'm trying to perform FFT for large set of samples,

Sampling Rate : 1 MHZ

No. of Samples Captured : 1 Million (1 sec duration)

currently what I'm doing is, I've added zero padding so that it matches to 2^n, and now the total number of samples are 1048576 (2^20) and then I perform FFT. This approach seemed to take long.

I'm just wondering if there's any efficient way to do this? (Please note that at this stage, I'm not particular about the frequency resolution)


texts: How to make a circuit diagram for a PDF document?

texts:
SmartDraw seems nice but is not free.
Circuit Lab was way easier to use, but I could not even rotate the "current source" arrow to point in the upward direction

Circuitikz involves typing in coordinates, which is more inconvenient than dragging and dropping icons.

Is there a free software (preferably an online editor but ok if it is not) that is good for making circuit diagrams?


texts: What does a syntax error mean when it says: "near text "else"; expecting "end", or "(" "?

texts:
I just don't think the word "near" is specific enough. Am I missing something before or after the word "else"? I'll put the code below and the errors after it. Thanks in advance!

library ieee;
use ieee.std_logic_1164;
use ieee.std_logic_arith;
use ieee.std_logic_unsigned;

entity decoBCDto7 is
    port(
            binary:     in std_logic_vector(3 downto 0);
            EN:         in std_logic;
            display:    out std_logic_vector(6 downto 0));
end decoBCDto7;

architecture internal of decoBCDto7 is
begin
    process(binary,EN,display)
    begin
        if(EN = '1') then
        with binary select
        display <=      "0111111" when "0000",
                        "0000110" when "0001",
                        "1011011" when "0010",
                        "1001111" when "0011",
                        "1100110" when "0100",
                        "1101101" when "0101",
                        "1111101" when "0110",
                        "0000111" when "0111",
                        "1111111" when "1000",
                        "1100111" when "1001",
                        "0000000" when OTHERS;
        else
            display <= "0000000";

        end if;
    end process;
end internal;

Error (10500): VHDL syntax error at decoBCDto7.vhd(19) near text "if";  expecting "end", or "(", or an identifier ("if" is a reserved keyword), or a concurrent statement

Error (10500): VHDL syntax error at decoBCDto7.vhd(19) near text "then";  expecting "<="

Error (10500): VHDL syntax error at decoBCDto7.vhd(32) near text "else";  expecting "end", or "(", or an identifier ("else" is a reserved keyword), or a concurrent statement

Error (10500): VHDL syntax error at decoBCDto7.vhd(35) near text "if";  expecting ";", or an identifier ("if" is a reserved keyword), or "architecture"


texts: How to get equal number of clock cycles before ISR on an AVR

texts:
While writing a time critical piece of code for an Attiny13, I figured I could use the rising edge of an input as a trigger to read in some self clocking data. However, the number of clock cycles needed to go into the interrupt routine differs depending on the instruction being executed at the moment.

How can I ensure the time from rising edge interrupt until start of the interrupt routine is always the same number of clock cycles?

Except for the interrupt routine there's no code running at the moment, so maybe there's a way to loop with a single instruction in the main code?


texts:
In Altium Designer (v.16.0), I would like to assign several resistors with the value "R", and being able to change them only by assigning the value of R to e.g. 10k, at some place of the application.

I've been unable to seek this on internet nor in the tutorials, i always got with the Parameter concept, which are the standards values specifying the components. I am thinking on general values, like global variables, or local variables per Schematic, so you can use them as in a design stage, eventually using operations such as R/2 or 2R, etc.


texts: Modifying USB Battery (Portable Power Banks) to charge while charging (to use as ups)

texts:
I've been checking all the questions and can find many similar ones, but unfortunately none that addresses my problem. I ended up reading many interesting questions and answers (including e.g. this one Can i connect Power source (like usb charger) parallel connection with power bank output for keep Uninterruptible power supply (UPS))

I however already have a few PowerBanks mainly something like this. I would like to use one of them as a ups, but my problem is it does not seem to charge when it is charging. Is that a "feature" of the battery, or is it to "protect" me from wearing the battery down? How difficult/dangerous would it be to disable that feature? Could i just go ahead and get the power directly from the end-poles of the batteries bypassing all circuitry, or that would be dangerous?

Last, I have a second brand of powerbank, this one. Here things are even more complecated, as the battery requires me to press a button for it to start charging... Is this standard?

I have seen it be done, since I have found that there are similar power banks out there that can fact provide while charging e.g., with other power banks, e.g. http://raspi-ups.appspot.com/en/index.jsp. It also seems to be an "ok"-ish thing to do (https://www.quora.com/Is-it-okay-to-charge-your-phone-through-a-power-bank-while-the-power-bank-itself-is-being-charged)


texts: Why am I getting this oscilloscope reading? (Half wave rectifier)

texts:
I’m trying to use a half wave rectifier with a capacitor filter and instead of getting a ripple voltage at the output it’s giving a signal that looks like white noise(pic below). Any ideas?

(a signal similar to what i'm expecting):
here is the circuit diagram (with a function generator 12vpp/60hz instead of transformer):
parts used-
capacitor : 2200uF
resistor : 10kOhm
diode: 1N914


texts: What type of plug is this (larger than a europe round prongs)

texts: I have this plug for a eletric shaver but it doesn't seem to be a europe plug. I need to buy a adapter from this to US but don't know what this is.


texts:
In the image:

Channel 1: Drain to source voltage
Channel 2: gate to source voltage
Channel 3: Switch current
Channel 4: Load current

The image shows Vds of low side MOSFET at turn on measured with a passive and differential probe seperately. As you can see, differential probe has a skew compared to passive probe, which is understandable.

But: Why does the reading, after turning on the passive probe, become negative whereas the differential probe still shows the correct reading?


texts: Can a 10uf Capacitor be used in place of a 15uf capacitor temporarily?

texts:
I am in Phoenix and it's hot. The indoor blower motor just went out on our AC unit and the wife and kids are not happy. It is just a bad capacitor.

Original capacitor is 15uf 440v. I was able to get one on Amazon that will be here in two days but it is only 10uf 440v. Will this be alright for a week or two until I can get my hands on a 15uf 440v capacitor or is it dangerous?

Thanks in advance.


texts: Two layer FR4 PCB: should you place GND pour on signal layer?

texts:
Talking about two layer PCB's FR4 due to lower cost:
I always poured ground on both layers of the PCB, I believed "the more the ground the better", but Recently I started watching altium live presentations, and I came across this video gem to 40:23,. In short, Eric Bogatin talks about pouring GND on signal layers, he says that this is bad (note that he talks about high speed signal lines PCBs). And he says it is not a good technique, because adding copper pour on signal layers makes the gap between traces conductive, and results in cross-talk (signal bouncing), and only if you add vias everywhere between tracks you will reduce dross talk.
At the end he presents all the data in one graph:

Blue: cross-talk with GND pour full of vias (best scenario)
Red: No GND pour on the signal layer (the optimal he suggests)
Purple: GND pour on signal layer with two vias on each end (what I see eveyone suggests, Eric shows that it makes cross talking worse).
Black: Pour that is floating (No one does that ok)
But he does not talk for slow signals, he only uses examples of <4ns rise time signals.
My question is: On two-signal layer pcb design, where I do not design any ridiculously fast signals (like DDR memories, CPU signals with fast rise edges),I also take care to put signals on the top, not splitting the GND on the bottom and at the worse scenario I use Buck/Boost converters, which I place far away from my signal layers, and my atmega to drive a stepper or servo motor.
So question is: should I pour copper on my signal layer on FR4 2-layer pcb? What is your experience with two-layer pcbs on GND pour everywhere?
And here is my approach, which I think will be the best thing to do:

I had to trace that big power trace on the left on the bottom, it interrupted my GND plane, so I put some GND on the top, so the current can go over this obstacle, not around it.
I also try to place GND Vias close to tracks whenever they change layer. So when a signal goes from bot to top or vise versa, it will have two vias. One for the trace to change layer, and one GND via close to it.


texts: Connect FPGA without FMC connector to external ADC board

texts:
I'm working on a project to sample signal at 500MSPS with FPGA and ADC. Since I cannot design IC myself, I want to find one external ADC board that can be directly connected to my FPGA board. I have searched online and only found ADC board with FMC connector can work at 500MSPS or higher. The FPGA board I'm using is Digilent Anvyl Spartan-6 FPGA board and it doesn't have FMC connector.

I have finished previous project connecting this FPGA board with AD9226 via 2x20 pin connector working at 50MSPS. I don't have any budget for buying a new FPGA board so I hope I can continue using this same one.

Is there any solution for this without replacing the FPGA board?
Could I find any ADC board which can work at 500MSPS with pin connector?

Thanks!


texts: Positive Level Shift a Clock Output using Diode?

texts:
I need to level shift a 26mhz 1.8v clock output by .7v on both the high and low side (so clock swings from .7v to 2.5v on output).

Would a simple diode/resistor setup like below work for this?

https://www.circuitlab.com/circuit/6v24nh/screenshot/540x405/

I did a simple circuit to simulate this, and it seems to shift the single nicely and clock output looks clean on scope, but its amplitude is shortened, so it swings from ~.9v to 2v, which I'm assuming is from the 1k ohm pull up I'm using. Some cutoff is fine, but how would I get this closer to 2.5v on the high?


texts: Ladder diagram, variation of Latch and Lock

texts:
I have  a problem for expanding this particular ladder diagram. The cylinder is a double acting pneumatic cylinder type.
START -> Start button
A+ and B+ -> Cylinder moving forward
A- and B- -> Cylinder moving backward

For this sequential
    START > A+ > A- > B+ > B-
Basically when START button is pressed, Cylinder A will move forward until Max, then move backward until Min. After Cylinder A moves, Cylinder B moves just like A. Forward first until Max, then backward, until Minimum, then it will be RESET.
It goes like this. (sorry for potato quality)

From that, I understand that it's just a Lock and Latch.
But, for this sequential
    START > A+ > A- > A+ > A- > B+ > B-
for the love of God, I can't figure it out. How is the ladder diagram?
Also another question, how is the ladder diagram of a Monitor button (only has one button)?
Anyone can recommend comprehensive books/guides or software simulation for this?
Thank you.


texts:
I tried to do an exercise from my textbook where I have to apply the Thèvenin theorem, but can't solve it. I got stuck at one point.

Given the circuit in the picture find the I current by using the Thèvenin theorem.

simulate this circuit – Schematic created using CircuitLab

I found \$R_{Th}\$ and \$v_{Th}\$ first.

(a) To find \$R_{Th}\$, I powered off all independent voltage generators (that is \$E\$) and so I found \$R_{Th}=\frac{R*R_1}{R+R_1}\$

(b) To find \$v_{Th}\$ I applied the voltage divider: \$v_{Th}=E \frac{R_1}{R_1+R}\$

simulate this circuit

After this I got the Thèvenin equivalent circuit:

simulate this circuit

And now I don't know how to proceed. Maybe I'm wrong with the above calculations too.
The text says to try to solve it with the Norton equivalent circuit too.
I'll sorry in advance for the triviality, but I'm doing a basic course at college and I've never did it before. So, please, be comprehensive.
Thanks who will reply.

EDIT: So, I managed to do it till the point to calculate \$R_{eq}\$ and \$v_{eq}\$.
Finally I got this circuit:

simulate this circuit

Where \$R_{Th}=\frac{R R_1}{R+R_1}\$, \$v_{Th}=E\frac{R}{R+R_1}\$ and \$R=R_3+\frac{R_4R_5}{R_4+R_5}+R_6\$

Now I have: \$v_{AB}=R_{Th}i_1+v_{TH}=-R_{Th}i_2+v_{TH} => i_2=-\frac{v_{AB}-v_{Th}}{R_{Th}}\$, but the book report in the solution that \$I=i_2=\frac{v_{Th}}{R_{Th}+R_2}\$. Why is that?


texts: USB IF specification for back powering Hubs

texts:
Is there any design specification in the USB forum that states what amount of back powering current from a device to a hub is allowed?
I understand that it may be zero but I also can't seem to find such a condition anywhere in the documentation.


texts: Best practice to keep main() in embedded systems

texts:
I would like to know one thing about keeping the main() in embedded coding practice.
I have a stand-alone system that have n number of states and it would be shifting  to the respective states.

At first I did a while(1) condition in main() and checked for any of the states to occur:

main()
{
  initialize;

  while(1)
  {
    check for state n.

    if state n found

    GoTo state n
  }
}

I don't know whether I made a mistake by defining the state n inside the main itself. Or should I separate the state n definition by separating it from main() and calling the state n function from main()?

I want to practice the best coding standard. What is the best practised method in embedded systems to keep the main()?

I would like to have inputs from your part to have the best structure for defining embedded coding methods to keep main() and corresponding source files.

What will be the case when the states become elaborate and complex?  How should I keep the main()?  I trust coding needs to be kept tidy.
I would appreciate your valuable inputs and suggestions.


texts:
I'm hacking a design who is already made with a PIC32MX in order to attach a FTDI CHIP to the actual design. This FTDI it should serve a purpose to make a "bridge" between USB and UART in the way to put this Fingerprint Reader working properly.
I am not using any UART communication because I don't have any more UART Ports available. That's the only reason why I am trying to put the USB module working.

The VUSB pin is connected to the VCC_3V3 but in the datasheet it's mentioned two opposite information. In the page 41 they say "USB internal transceiver supply. If the USB module is not used, this pin must be connected to VDD." and in the page 45 it's mentioned "Note 1: If the USB module is used, this pin must be connected to VDD." What should I do?

The power to the FTDI is given by the 5V regulator and I am not using (ignoring) the VBUSON pin 11 neither the VBUS pin 34 and I have the FTDI connected to the USB pins 36 and 37 for D+ and D-.

Regarding that I am using the pin 11 to reset the Bluetooth module which I have in the design, do you feel that I really need that pin to put the USB working properly?

What should I do with the pin 34 (VBUS)?

To put the whole system working correctly I must configure the USB as CDC Host, right?


texts: Voltage Level Translation: LCD(5V) -> GTL2000  MCU (3.3V)

texts:
I am trying to interface a micro-controller (LPC11C14) to a LCD. The LCD has Vih = 3.5V so I cannot directly connect the uC pin to the LCD. For this, I found a GTL2000 chip which looks like it might do the job. But here is the issue that i am not sure about.
I want bi-directional voltage translation because I want R/W facility with the LCD (for reading Status Read). I know that I can set the outputs of this CMOS microcontroller to open-drain, but I am not sure about the LCD (I don't think they are open drains). So I modified the bi-directional circuit shown in the datasheet to include resistors on the open drain side. The clamp resistors are calculated through specified formulas in the datasheet. GTL 2000 Example circuit
My question is this circuit likely to work?
Also, if I don't put the uC pins in open drain mode, I can remove the pull-up resistors on that side. Is that possible as well? The datasheet does not talk about standard GPIO behavior.
Thanks,
The LCD being is NHD-12864WG-BTGH-T#N, which has a Voh of 3.5V.


texts: Identify a cylinder or thick washer for bolts

texts: It must be obvious to you but I can't figure out the name of that part which I need to replace. It's added to the bolts that hold the PCB to the case so as to create a large enough gap between the two. It's basically a metal cylinder.


texts:
From the pics I saw in some websites and from what I read so far I can assume that it is a film capacitor, but I am confused. I would appreciate it if someone told me what type of capacitor is this :

http://s23.postimg.org/3kmxdurtn/20131123_020105.jpg
http://s7.postimg.org/nqz2l825n/20131123_020027.jpg

and can I replace it with electrolytic or ceramic ones? And what about the voltage since there isn't any description on it, there are some other electrolytic capacitors  with these volatages: 6.3 V, 16 V, 25 V on the same board. I found that 333K means that the capacity is 33nF.It is on a board of a Netgear DG834GT router, the output from the power adapter is 12 V , 1.0 A.

P.S. The power adapter is OK. I tested all capacitors in the board, others were okay and that one didn't work.


texts: How to use the electricity from a generator in an efficient way

texts:
I'm looking to buy a generator for producing electricity to power different things (e.g. a fridge), in a place where there's no electricity.
For now, I do not have a fridge but I may have one in the future (it's an example of a device that needs more power).

Currently I'd need electricity to recharge my MacBook Air from time to time (probably once a day or so).

I guess the generator produces more power than my Macbook Air will use. I just assume that the other unused part will be just wasted.

I'm thinking that there should be some kind of batter/power bank which stores (almost) the entire electric engergy produced by a generator and then I can use that power bank for recharging my laptop few times.
I have the feeling this would be a little bit more efficient than using the energy produced on the fly.

Is my assumption about the waste correct?
What would be the optimal way to charge my laptop having one of these 220V generators which are available in the shops?
Do I need a power bank? Something similar would be handy because hearing the generator noise is not a very pleasant feeling I think. What is the name of such a power bank device?

Is there an even better solution for charging devices like a laptop, phone etc. than a 220V generator?

I have no experience in knowing how such generators work, but I have the feeling that my laptop can be charged, but it's going to use just a very small percent of the produced energy. I don't want to waste the gasoline which is used to power the generator.

When referring to a generator, I mean one of these portable gasoline generators. Is there anything better for my case, keeping in mind that maybe later I want to power devices that may need more power?


texts: ATtiny85 Yikes Error While Burning Bootloader

texts:
I'm using an Elegoo uno to burn the ArduinoISP example code on to an ATtiny85 SMD. I wired the board according to the "#define USE_OLD_STYLE_WIRING" using pins 13/12/11/10. The wiring diagram for the circuit board is here. I first upload the sketch as "Board -> Arduino Uno" and it uploads successfully. I then click burn bootloader, using the following settings here. I get the error listed below after trying to upload to the ATtiny85. Any ideas?
https://gist.github.com/gmanc2/8e0b354d75c80d648f526b03fd6f8cf1
code: https://gist.github.com/gmanc2/683803105034c2c1ac1393d1f6b26cef
I have run the burn code only with the 1mhz internal crystal and 8mhz internal crystal selected. I if it is the case I accidentally selected an external crystal source, I don't have any 1-8 mhz external crystals. This error happened on my second attempt to burn to the board. Are there any other options besides buying a crystal? I'm fairly certain my wiring is correct. I have an oscilloscope is there any way I can verify the clock speed?
Thanks for any assistance!


texts: What Voltage/Current Levels Can I Send Into the Microphone Input on a Mobile Phone?

texts:
I have a device that is sending 9600baud using only Tx, Rx, and Gnd.
I am not sure, but I think the voltage is either the 3v or 5v level.

I want to receive that serial data on my mobile phone.

I have found AFSK code for decoding on the mobile phone, however I am concerned about sending the 3 or 5 volts into the microphone circuit.

Can anyone help me understand what I need to do to the RS-232 voltages in order to step them down properly for the microphone circuit on the phone?


texts:
I have a problem with a project I'm working on. I am modifying a nerf gun for my son and running into a issue. I know I'm over powering the stock system with more power. Originally it came with 4C alkaline batters an I have altered it to take a 12v 1.3a security back up battery. Others has upgraded and has ran this same setup with 15 v on 10 AA batteries. My issue is that after about 10 seconds the system acts like the battery is dead. On the charger the battery is charged. After a few hours on the charger I'm back up to about 10 seconds. The motors turn full speed each time as they are fine. Two small batteries shouldn't kill a battery that size that fast. After using and testing the battery is testing fine on the multimeter. And if it is the motors why would they still work after some time of rest. Any guidance is appreciated.

Anthony


texts: Data Output Rates for dsPIC Microcontroller

texts:
I'm designing a high throughput data collection and transmission device, and I'm currently looking at the dsPIC33CH128MP202 as the central device. I have one signal that I am converting to a digital signal, and alternating between the main core and secondary core ADC modules to increase my sampling rate. After conversion, the conversion data needs to be output to an external transmitter to be read by a central data collection device. When looking through the data sheet, I see the SPI module as the fastest option with a maximum clock speed of 40 MHz. While I have an ADC sample rate that can work with this, the ADC modules are capable of higher sampling rates. As a result, I feel limited by the output rate of the SPI module. I have included a basic graphic of what I'm working with below.
Is there a way to achieve a faster data output rate than the 40 MHz of the SPI in the dsPIC device? For instance, could an external device access data in the dsPIC via one of the DMA modules? If so, would that be based on the MIPS of the dsPIC device and/or the MIPS of the data collection device/transmitter?
The other issue that I've run into with this is the limited number of SPI modules. I'd like to be able to use more than just two of the four ADC modules in the dsPIC. If there are other methods of exporting the data, that could solve this issue as well. In this case, I would be looking at using the secondary core for data conversion (3 ADC modules) and the main core for data output. In this scenario, would it require one instruction to send a bit to the MSI module, one instruction to read the bit into the main core, then further instruction cycles to output that data?
Thank you all for taking the time to read through my questions, and I appreciate any guidance you all may have.

Edit:
As questions pop up, I'll try to answer them here.

What kind of transmitting device are you planning on using which supports those sorts of data rates?

The transmitting device and network protocol haven't been selected yet as I'm still in the early stages of the design process. I'm picturing a dedicated SoC device, but that will depend on the network protocol that I use.

Just so we have the whole picture, how many samples per second do you need to send?

The ADC modules on the dsPIC device have a maximum sample rate of 3.5 MSPS. I'm looking at setting a trigger for 3 MSPS on 2 or 3 ADC cores in the secondary MCU core. The ADC cores will have offset triggers for an effective sampling rate of 6-9 MSPS.

Also, are you doing anything less than bright like trying to send ASCII? Forgive my asking, but this does happen, without people realizing that sending binary could make problems go away.

The data will be coming directly from the internal ADC cores, which is in the form of a 16-bit word. From my understanding, the data is stored in binary in the ADCBUFx register.

Last point, 40MHz is your SPI Clock, not the SPI data rate. I'm going to assume that the SPI word to be sent is at least 8 bits, so your data rate is going to be no faster than 5MHz.

Yes, that's what I was realizing this afternoon. The ADC outputs a 16-bit word, which would only result in an output rate of 2.5 MSPS. The dsPIC device only has 3 SPI modules as well: 2 in the main core (1 with 40 MHz maximum clock and 1 with 15 MHz clock) and 1 in the secondary core with a 40 MHz maximum clock.


texts: When we can say 0 and 1 in digital electronic?

texts:
I'm confused when seeing wires contain GND and VCC in a schematic. Mainly their flows.
I never confused when see in digital logic wires schematic like logic gates. I understand  flows in digital schema.
Meanwhile i don't understand how flows in electronic schemes due to there's two flows like conventional flow (VCC to GND) and electron flow (GND to VCC) that's will be problem for me about its state.
So, do u think contain or much electrons in a wire means 0 or 1 state? Or there's no relation?
I know HIGH voltage means 1 which it's VCC and LOW voltage means 0 which it's GND. But, Aren't unconnected wires means 0 state too? Because it  contains 0 volt in wires. But also it's not work in some devices when disconnect wires to express 0 state.
The problem is when i want identify, analyzing, and solving digital logic in wires.
Like this picture below,1 state in red color, black means 0. But theres no blacked wires on below.
consider input A is constant 1.
Then the output (LIGHT) is always 1. In same wires, input B is variable, but there's no way to turn off the light (make output 0 state) because when B=0 the output still 1. It's because A+B = 1+0 = 1
And moreover, if B=1 then A+B = 1+1 = 1
This digital scheme truth table same as OR gate. But im talking about directly connected wires. Which will it affect to other wires or not in digital electronic scheme which contain VCC and GND.


texts: How to add a LED indicator to report LDR sensor error using PIC?

texts: I have this simple light sensor project using LDR. The PIC reads an analog signal 0-5V from LDR and will turn on the relay ON when it's bright on and off when it's dark. I want to add a simple LED indicator that will turn ON when the LDR is broken or something, but I don't know how to do it.


texts: Switching high current and high voltage for coilgun

texts:
I am building a multi-stage coilgun and need to be able to electrically switch 450V and over 100A somehow (virtually shorting large capacitor bank)... I've tried using IGBTs but fried them. I also need to be able to turn it off so I can't use thyristors either. It also needs to be able to turn on and off relatively quickly since it is multi-stage. What is the best way to do this?

The logic runs on 5V so I currently (no pun intended) use a MOSFET to control the gate with 20V (I have a variable boost converter which can go up to 40V)

Thanks!!


texts:
I'm trying to modify an op amp to simulate its worst case behavior at end of life.  In the common mode effect section of the LM124/NS I have the following

EOS 7 1 POLY(1) 16 49 1E-3 1

What is the function of EOS?  I've been searching online for some information about what it does but to no avail.

Thanks


texts: Can I re-use pins that are labeled as the same physical STM32G4 Nucleo pin?

texts:
Poorly written question. Let me elaborate.

The Nucleo-32 board I'm developing (STM32G431KB) in STM32CubeIDE shows on the CubeMX "pinout view" that there are 4 distinct pins PA6, PA15, PA5, and PB7, each with their own unique set of alternate functions. I assigned a function to each of those pins (although you don't see PB7 or PA15 populated in this image for reasons discussed below):

So after configuring my peripherals, I then went about wiring the board according to the ST User Manual. That's when I realized PA6/PA15 and PA5/PB7 are both assigned to a single pin for each pair (header CN3, pins 7 and 8):

My question is thus: am I prohibited from using a pin if I am simultaneously using a completely separate pin on that same physical header pin? For example, if I'm using alternate function SPI1 SCK on pin PA5, is there no possible way to use pin PB7 for anything at all? Or is there some sort of fancy GPIO muxing feature that I'm not aware of?


texts: Best circuit to play music in car, using ISO 10487

texts:
instead of using a radio, I want to install a Raspberry Pi 3 with my own features in the 2Din Slot, so I have to make my own circuit to play audio. I tried with the following modules based in LM386 pic:

It doesn't work bad at all, but neither good enough, the max volume is not as high as I would like it to be, the sound is not clear, starts to crackle if I increase it, and the bass level is so bad.

Should I try with my own LM386 circuit where I select my own resistor and capacitors till I get the sound I want? should I look for another circuit? another device? maybe something like an equalizer? I would like it to be small enough and as customizable as possible. Also, high bass is one of my priorities.

Voltage is 12.6v
Speakers resistance is 4ohms


texts: Calculating phase currents of an automotive alternator

texts: I have an automotive (3-phase) alternator with peak rated output of 150A at 14V (after rectification, of course). How can I determine phase (AC) currents in this situation?


texts: Decrease in stored energy after connection of another capacitor

texts: A 3-µF capacitor charged to 100V is connected across an uncharged 6-µF capacitor. So the initial stored energy is: 15mJ and the final: 5mJ. What happen to the 10-mJ of energy?


texts:
I developed some hardware with an STM32F4 and firmware and want now to protect the firmware as good as possible when the product goes out. Since I use two flash sectors for virtual EEPROM memory, I still want to access them for r/w. Now I had a look at the option bytes in the STUtility and see there readout protection aswell read/write protection for different flash sectors.

Is it enough for a good protection (I know there were some problems also with the best protections in the past and that a person with enough knowledge can access the code) to choose the read out protection level 2 and then choose the read/write protection for any sectors expect the ones choosen for the virtual EEPROM emulation?


texts: ADXL 335 Accelerometer incorrect Output. z and y axes always the same

texts:
I have an ADXL 335 Accelerometer. I'm checking its output voltage values using a multimeter and I'm consistently getting the z and y axes giving me the same result. How do I trouble shoot this problem?

I have attached a picture of the accelerometer. The male to male wires were used for voltage readings. The 5 coloured header pins are providing data to the MSP that we are using to send information to the laptop. The MSP is powering the Accelerometer.

I have checked the resistance between the z and y pins, there is no visible resistance.


texts: Played with some lead solder without washing my hands for awhile, should I be concerned?

texts:
I was using some lead solder at work, and wasn't aware it was lead solder nor had anyone told me that it can be dangerous.

For the most part I was just handling it. This was last week and I don't think I washed my hands afterward.

I know this may be silly, but is that anything I should be concerned over? I can't imagine my low exposure would be worrisome, it's probably something that multiple hours every day for years would cause issues over, but I just want to make sure.


texts: Connecting op amp circuit output to ADC makes signal asymetric

texts:
I'm connecting an electric guitar to amplifier circuit and the output of the circuit to ADC. I've checked the output of amplifier with the osciloscope. The signal seemed fine, but after connecting it to ADC (maybe because of capactive load?) it become asymetric. The output signal doesn't go below ~500 mV when the output is connected to 'something' (I've tried also to connect it to hifi stereo system, with the same result) so it gets badly distorted. I need it to be in range 0 - 3 V. How to get rid of this effect?

Op amp: LM324
ADC: MCP3202
R1, R2 give DC offset by 1,5V. R1+R2 = 1M
gain close to 1

EDIT
I've tested the circuit with square wave to illustrate the problem.

On the first plot below is the unloaded version of the circuit (op-amp output isn't connected to anything), Vmin is 80mV which is almost what I want.
On the second one we can see the loaded version, output connected to hifi, however conneting it to ADC results in the same effect, Vmin doesn't go below 500mV:


texts: Unidentified Inductor type - opposing turn wound toroid?

texts:
This will be an odd one to describe, but from a high power APC Symmetra UPS, these inductors are used in the AC output filter (HF sine wave). There are 3 of these per AC leg, in series, with no capacitors.

They are wound really odd, and I want to know why! (pictures below)

If you take a length of wire (about 10 feet?), feed 1/2 of the length through the core, and start winding BOTH ends away from the initial wire insertion point... BUT BOTH ENDS GO IN THE SAME DIRECTION around the toroid core... just wound in opposition (one wire leg goes CW, the other CCW).

When you finish winding (same number of turns on each wire leg), you end up with both ends of the wire arriving at the same point... and these are the terminations.

It somewhat reminds me of the Tesla Bifilar Flat coil... but on a toroid, and only one wire.

(If you're up for one more oddity, explain that 4-path small copper trace on the bottom side of the filter board - last image below. There's no connections to them)


texts:
How to control a voltage using PWM out of a microcontroller that can handle a load consumes 20 Amp current..

Load is a heating coil that has a resistance of 0.21 Ohms, power supply 4.2 v Li-Ion battery, PWM 0 / 3.3 volts ..


texts: Failing to understand and to fix a PWM spindle controller circuit

texts:
My CNC controller worked for many hours without trouble. But recently the resistor R5 (red circle) started to melt each time I switch my CNC spindle on, and even at low RPMs. It is 100 ohms, compared to the large 2 ohms R3 and R4, so why does it drive so much current? And without blowing the optocoupler?

The schematics below was reverse engineered, so it may have some little errors, but I checked that it matches the circuit I am trying to fix.

Also, I do not need the STOP signal at the bottom (any clue what is it for btw? PWM feedback?). So removed R5 completely with the idea I would "remove" the loop in the bottom right of the schematics, but it then prevents the spindle from turning at all. How can it be?

Other hints:

The spindle power supply line reads about 60VDC instead of stated 48V.
the spindle resistance is about 2 ohms, the fuse never melts
Initially, I realized that R4 was not soldered properly but I fixed it before changing R5 again. No luck, R5 burns again after a few seconds.
I checked the PWM signal with a scope (OK), the MOSFET gate-source (Q1), the flyback diode (D4), the AL817 opto diode (U3), and they all seem OK.
The C9 capacitor is larger than stated on the schematics (1000uF in place of 100). It is also OK, but the polarity leaves me puzzled.


texts: Could I use the foot pedal of an electric sewing machine to control the speed of rotary tools?

texts:
I am searching for a solution for powering power tools with lower noise levels.  I live in an apartment and have many neighbors around me.  When I have little projects,  I don't want to disturb my neighbors. For example when I have to use the angle grinder it would be enough for me to use it half the speed or the hand planer as well.
I have the pedal of an electric sewing machine laying around so I thought about using it as a speed controller for the tool.
Would it work exactly like a commercially bought variac/ light dimmer? When not, what would be the difference?
Is this plausible and possible?


texts: Calculating the flat band voltage of MOSFET through graph

texts: I have obtained the Capacitance v/s Voltage(DC) as well as 1/C^2-V graphs of a MOSFET. Now I'm aware that flat band voltage corresponds to that voltage when energy band diagram of semiconductor is flat. How do I realize this fact using the graphical approach and calculate the flat band voltage?


texts: ESP32 CAM gpio0 permanently grounded. how to fix?

texts:
I bought an ESP32 CAM and flashed it, I connected the UART with example code on the board but always got this:
rst:0x1 (POWERON_RESET),boot:0x3 (DOWNLOAD_BOOT(UART0/UART1/SDIO_REI_REO_V2))
waiting for download

it always enters boot mode because the gpio0 is permanently grounded.
I checked with a multimeter and those pins are connected.
I don't see any wrong soldering anywhere.
what can cause this issue?
how can I fix it?
If I saw where it's connected I would scrape the PCB connection but it's not the case.


texts: Pull-up vs Pull-down for contact switch?

texts:
I am designing a simple contact switch(tactile, which conducts when you pushes, and springs back to not-conducting when released) interface with a microcontroller.

It's GPIO has option for both internal pull-up and pull-down.

1) Which one should I use? For 2 layered board, pull-up makes me easier to do PCB artwork, since one-end of switch connects to GND.
Other than that, is there any difference or reason for me to use one configuration over another?

2) Is there any possiblity that  the noise from physical contact make MCU malfunction?


texts: Small signal resistor of emitter in CE voltage amplifier

texts: in such a small signal model of CE circuit. Why "re" ( the small signal resistor of the emitter = VT/IE ) is not represented? However, I've noticed that it is shown in CE amplifier with emitter degeneration  and also in CB, but not in CE without emitter degeneration nor CC amplifier circuits!


texts:
I have a 2”x72” belt grinder with a Brook Crompton bf4n.75-2 motor.

It is connected to a Teco L510 VFD.  Running here in the United States on 110v. My question is about turning up the RPMs sometimes when working on projects and hogging out material.

Is this doable? What would be the safest RPM without causing damage to the motor or bearings?

I know with my VFD I can up the frequency to do so and have seen many people do it. Just don’t want to do this if it is going to burn up my motor.

Normally 1800ish RPM is fine but every so often at the start of projects it would be nice to get the belt moving a bit more and removing material.


texts:
I'm wanting to create a basic digital camera, I have most of it figured out... except for the image sensor itself. Looking in the normal places (digikey, mouser), I'm finding some very basic, low resolution, poor performance sensors from Omnivision. Realistically, I'd like the camera to be able to take somewhat decent photos, and I don't have much experience with optics, so I'm looking more for an integrated solution, much like a camera module from a smartphone.

Am I going to be able to order small quantities for prototypes from companies like Sony (who to my knowledge have done the past iPhone cameras)?

Does anyone know where I would get started reverse engineering the iPhone 5s's camera module? It's relatively inexpensive (40 dollars or so from iFixit), I'm just not sure how I could even go about starting to understand how to talk to it, seeing as I wouldn't be able to get a datasheet. Would it be possible to find a cable with the correct connector to bridge the connection between a dummy iPhone and the camera module probe the communication (are the tiny connectors available, or are they proprietary?).

Lastly, is this the right direction to go with this anyway? If I develop something useful and would like to sell/mass produce it in the future, am I going to be able to ask sony for a camera module that's compatible with the work I've done?

Thanks guys! I couldn't find much information in this space, other than what Mike Harrison (from mikeselectricstuff) has done with the iPod nano camera. Thanks for your help.


texts: RF Antenna Matching circuit and PCB design for 868 MHz SigFox device

texts:
I'm designing a Sigfox sensor device based on WISOL/SFM10R1 a SigFox verfied module by WiSOL and Atmega328.

I need to understand the parameters for 868 MHz RF Antenna Matching circuit and PCB trace width needed for the design. Following are few design layout and sketches.

I'm attaching a 50 Ω external antenna to uFL connector on board. Currently trace width of track from WiSOL module to uFL connector is 0.6096 mm

Schematic:

Component value here are not correct and thats what I want to know the way to calculate it.
I'm not a RF expert its difficult subject for me.

I found one online calculator which I tried to use as a simple guide at
https://www.eeweb.com/tools/microstrip-impedance for calculating
trace-width. But as per my current parameters I'm getting trace-width of approx
3 mm which does not looks practical.

Parameters:

Trace Thickness: 17umm (I hope this means copper thickness)
Substrate Height: 1.6mm (This is probably PCB thickness.)
Trace Width: ?
Substrate Dielectric: 4 (I'm using FR4 PCB board so i guess this is ok)

Freq: 868 MHz

I have few questions here:

Which calculator should I go for - Microstrip, Symmetric stripline or embedded strip at the link I mentioned above, as im having double sided PCB and antenna trace is on top layer!
What will be the way to calculate value of component to match the antenna of 50  Ω
Does length of trace also matters?
Why I'm getting 3mm trace width? Where I am going wrong?
Whats the significance of those multiple vias added around antenna in most designs.
Any other suggestion to improve this antenna circuit design which should considered from certification point of view.


texts: Use of the same transformer with a replacement offline SMPS controller?

texts:
We have an SMPS that was designed by a third party. The controller, VIPER100, has gone obsolete. ST don't do any sort of direct replacement, but other manufacturers do  similar devices or at least controllers that use an external FET that would enable us to get the same power output.

Is it possible to use the existing transformer with a different controller? I appreciate, we'd likely have to tweak the opto feedback part of the circuit and it we'd have to ensure that the winding that fed the controller gave the correct output for a new controller.

Other than that, is it a sensible idea to just try and replace the controller, but use the existing transformer, or is better to have a new design done from scratch?

I know the basic theory how these off-line controllers work, I've done loads of inductor based dc/dc converter designs, but have essentially no experience in transformer design.


texts: How does high voltages of electricity coming from power plants also helps in saving energy?


texts: Two Op-Amp Instrumentation Amplifier - Gain derivation

texts:
I came across the following appnote(slyt647) which analyses the two op-amp instrumentation amplifier topology.

The gain was found by finding individual gains for each op-amp and adding them in accordance to superposition.
I have some hard time understading how \$G_{A1V-IN} \$ (eq 8) was calculated.

As far as I see it for \$G_{A1V-IN} \$ we have the following equivalent circuit:

And thus it seems to me that: $$G_{A1V-IN} = -\frac{R_R}{R_G} -\frac{R_R}{R_f}\cdot \left(1+\frac{R_R}{R_f || R_G} \right) $$

Did I go wrong somewhere ?


texts: I'm using an audio amplifier to produce a 15-20 kHz, 6 watt sine wave output into a pure resistive load.  There are some low-frequency components to this signal that I want to remove (mains frequency harmonics).  How is this best achieved?  I know how to construct RC filters for signal (i.e. low) voltage circuits but not power circuits.  Can someone give an answer about how I should design the filter and suggest components that may work?


texts: Control system stability with respect to gain margin and phase margin

texts:
I have learn from control system that for a stable system gain margin and phase margin both must be positive. That is the truth.

But I have a doubt about this simple third order type 2 open loop transfer function whose phase margin is positive but gain margin is NEGATIVE. But both Nyquist stability criterion and Routh Hurwitz's criterion are showing that the close loop system will be stable.

How is it possible? Am I doing something wrong?

The system is as follows :

\$\dfrac{K*(s+3)*(s+2)}{(s^2)*(s+1)}\$ and value of K is "1".

I will be very thankful if someone clears my doubt. I have checked the system using MATLAB also.


texts: Decrease voltage but keep same Amperage?

texts:
I have a controller which use 12V 3A. And I got old laptop power supply which is 19V 3A what resistor I need to include to decrease the voltage from 19V to 12V but keep the same 3A? Or I need to use any diode?
Here is the controller https://www.aliexpress.com/item/4000012888935.html?spm=a2g0s.9042311.0.0.67ca4c4dnQhqek
I have a Power supply at 12V 1A, but doesn't start properly. Seems it is weak as current. The most strange thing is that when I test it with multi meter shows not 12V but 16V.


texts: A problem regarding my Slayer Exciter circuit?

texts:
I have made a Slayer Exciter circuit for my school project. I'm going to be assessed on it.
Now, it works just fine. But if I have to light a tubelight or something, I have to touch the terminal to the wire sticking out of my secondary coil. Then I can move the tubelight about, close to the coil and it won't go off. But why do I have to touch my light to the wire initially? Because in most Slayer Exciter circuits that I have seen on the internet, the light only has to be brought close and not actually touched. Can someone please give me a technical explanation? The examiner may ask me this and more than that, I want to know.


texts:
How does the transistors amplifying function differ from when AC signal applied and just a DC voltage applied?
Thanks in advance


texts:
I have a system (call it a DTE system). It sends me data (UART) which I receive at a DCE(LPC4337). Now, DTE transmits with 2 stop bits where-as it receives with just 1 stop bit. How is that possible.
It would mean I need to interface the to 2 different UARTs in my DCE, right ?
Also, supposing I go for full modem(RTS and CTS control), how would this work out ? As I would be using 2 different UARTs to communicate with the same DTE.


texts: Connect signals to N.C pins in diode array (for ESD protection)

texts:
We created a circuit with diode array for ESD protection PN: IP4283CZ10-TBR (MFR: Nexperia)

Data sheet

As you can in the datasheet, there are some pins which supposed to be N.C, but we did connect them to the signal pins, as you can see here:

We afraid that this connection might explain some problems we see in our samples, for example- one PCB didn't communicate with UART until we removed the part and another circuit failed during first watchdog test (again, until we removed this part).

In the datasheet all I could find that is related to the N.C pins was this line that mention that the capcitance between N.C pin to signal pin is 0.07pF (sorry, can't upload another image)

Correct me if I'm wrong, but it doesn't say much (just that the pins are seperated using small value CAP, nothing about not short between them).

Hope you could help me understand if this what is causing the problem or is it something else.
We also use another 3 identical diodes arrays with same "connection problem", but they seem to work fine (Connected to RS422 RX,TX and Debugger lines)

The debugger we are using is J-LINK (using JTAG communication).


texts: What's the actual sampling rate of an ADC that is only enabled periodically?

texts:
Let's say I have and ADC that samples at \$f_{adc}\$ when enabled by a CPU. The CPU executes a loop in which the ADC is enabled for \$T_{en\_adc}\$ and the remaining time something else is done for \$T_{other}\$, so that \$T_{loop}=T_{en\_adc} + T_{other}\$. When the ADC is not enabled, samples are not stored anywhere, the ADC does nothing at all.

At what frequency I'm actually sampling the signal then? Is it still meaningful to talk about frequency and sampling rate?

(everything in second/hertz)


texts:
I'm interested in very low supply voltage boosting. 20-200mV, the lower the better. Usually such applications use zero threshold MOSFETs, but I'm curious if BJT will do the work too.

In the datasheet, if I extend the curves it appears that 100nA base current corresponds with about 350mV. Collector voltage is about 35mV. but transistor supposed to have leakage and this leakage alone (B-E and C-E) should be enough to keep the transistor from shutting off (100nA), even at voltages below 0.35V. So this seems to be too bad.

Hovewer, when I try simulator I get that (some generic model) transistors can have power gain of 2 at just 25mV (25mV E-C, 25mV +- 1mV B-E). I assume power gain of 2 is sufficient to run oscillator and then boost the voltage? This seems too good to be true.

Link for particular transistor for 'it depends' people:
http://www.secosgmbh.com/datasheet/products/SSMPTransistor/SOT-23/SS8050.pdf

I think it doesn't depend on a particular transistor, since properties of such small signal transistor appear to be very similar.

TLDR: Make a boost converter from 0.05 VDC supply to 1 VDC output with typical BJT.


texts: Measuring continuity on a car battery while connected - damage?

texts: If you were to put both leads on negative and positive terminals on car battery while connected and have the meter on continuity (the one which beeps), what happens and can it fry/ruin the electronics in a car?


texts: GPS PCB RF Design and Performance Impact

texts:
I have designed a vehicle tracker for two-wheelers which is installed in 500 bikes. I am facing an issue with GPS performance (lock percentage is quite low for more than 75% bikes). This makes me question 2 possible things:

GPS antenna quality from the vendor
PCB design of RF part of GPS module

For the first part, I have asked the vendor to share the RF performance and quality check report with me. In the meantime, I want to make sure that the RF design part on PCB is not impacting the performance.

Following is the snap of my GPS RF design part:

As shown in the design:

I have tried to put as many vias as possible around the RF part
RF trace width is calculated using microstrip width calculator
I have avoided putting any power trace near the RF antenna part and separated the ground plane.

I am using an external GPS antenna (through U.FL to SMA converter) which is placed under the front panel of bike (which is made of plastic).

Based on this, I have a few questions which might impact the performance:

U.FL connector is placed at the edge of PCB. Is it creating any kind of issue?
I have GSM antenna and module placed very close to GPS, which might hamper the performance (though I have tried my best to separate out the GND planes of these modules)
Any other inputs/thoughts based on your RF experience will help me a lot.


texts: Is it good practice to always assign initial value and reset signals in digital design?

texts:
I have read that initial values to a signal can be set in an FPGA since the design is "loaded into it" after power up. However, in ASICs we can only rely on a reset signal to put all signals into a known state. Thus, is assigning initial value to all signals in code that shall be synthesized a good practice?

I have also read that reset signals makes heavy use of routing resources in FPGA and also in ASIC requires to be routed everywhere. In FPGAs, not using reset in every single register is a way to reduce use of routing resources but am not sure what benefit it is in ASICs. Is it a good practice to find ways to reduce use of reset signal in synchronous design by not using it in some parts of design but use it in others?


texts: Calculating Battery required for solar powered motor

texts:
I have a 220v/50Hz/420w motor, I'm planning to use the simple design
 Solar Panel --> Charge Controller --> Inverter --> Motor

and i calculate battery requirements as follows:
 P = I * V,
 420 = I * 220,
 I = 1.9A ~ 2A

does this mean for a 40AH Battery, my motor will run for 20 Hours (10 Hours to not go below 50% of the Battery) ?

I think my calculations are wrong
thanks.


texts:
A few times I've been reminded that an object can have self capacitance and it's just not registering with me how this can be so. I'm sure there's a good explanation. Here's the explanation I am usually given but I'm still not grasping that capacitance can exist when there is only one "electrode": -

The implication of this is that if the outer sphere were massively distant from the inner sphere the formula reduces to: -

Capacitance = \$4\pi\epsilon_0\times a\$ because \$\dfrac{1}{b} = 0\$

This is used as the argument that the middle object has self-capacitance

See this as the follow on proof. Maybe I'm being stupid?

EDIT to ask a directly related question: -

I've correctly calculated that a 1mm radius ball will possess a so-called "self capacitance" of 0.111pF. If two such balls existed and were placed a million miles away from each other (in an empty universe) would the capacitance between them approximately equal 0.0555pF i.e. half of 0.111pF? This "guess" is based on the capacitance of a 1mm ball to an infinite sphere being 0.111pF and from the infinite sphere to the other ball is another 0.111pF.

Therefore, with 2 capacitors in series of the same value, the net capacitance is halved. I can't believe that this is true but I'm not really sure.


texts: I have seen some micro controllers can be flashed with USB port alone with some driver software. But for some micro controllers we have additional interface hardware for flashing between the PC USB port and the micro controller pins. Why this difference? Specific example is arduino which can be flashed directly from the PC, whereas freescale micro controllers need additional hardware for flashing and debugging. Can all micro controllers be flashed with USB port alone with specific driver software?


texts: MOSFET gets hot when PWMing car high beams as DRL lights

texts:
The idea of this project is to have my car's high beams work as daytime running lights (DLR), with reduced light output. The DRL would turn on with the ignition on, and turn off, either when the parking lights are turned on or the ignition turned off. I found a PWM circuit online that I used for reference: The easy or hard way to build a PWM dimmer, but instead of putting the load on the high side, I put it on the low side.

The MOSFET I am using is BUZ11A.

Now, I temporarily assembled the circuit on my car to see whether it would work, and it did, everything worked as I planned, but the MOSFET I used got so hot that it started to burn off the tape which was wrapped around its legs, so I pulled the plug. I did use a heatsink.

Can anyone help me out with this, what am I doing wrong here, what am I missing? I want it to work as it did, but I can't have this this burning up things under the hood :). I'm no expert when it comes to MOSFETs, I do have an understanding of basic electronics, as I took electronics classes in college.

Here's the schematic:

(Full resolution image)


texts: STM8S - Connect to ADXL345 Acceleration Sensor via Hardware SPI

texts:
After software SPI didn't work out I am now trying to connect to the ADXL345 acceleration sensor via hardware SPI of the STM8S103F3. But, of course, problems appeared again, why not.
This is my SPI-Init code:

void initSPIMaster(){
    GPIOC->DDR = (1<<MOSI) | (1<<SCK) | (0<<MISO); //MOSI & SCK output, MISO input
    GPIOC->CR1 = (1<<MOSI) | (1<<SCK); //MOSI& SCK push-pull

    GPIOA->DDR |= (1<<CS); //set CS as output
    GPIOA->CR1 |= (1<<CS); //set CS as push-pull
    GPIOA->ODR |= (1<<CS); //turn CS high

    SPI->CR2 = 0b00000000; //2-line unidirectional, Hardware-Slave  management
    SPI->CR1 = 0b01111111; //Enable CPHA, CPOL, MASTER; Baudrate: f/256, SPI Enable
}

This is my SPI-Transmit function to write data to the DR-Register:

void SPITransmit(uint8_t data){
    while(!(SPI->SR & (1<<1))){
        nop(); //wait until transmit buffer is empty
    }
    SPI->DR = data;
    while((SPI->SR & (1<<7))){
        nop(); //wait until not busy
    }
}

This is my SPIReceive function to read data from the DR-Register:

uint8_t SPIReceive(){
    uint8_t registerValue;
    while((SPI->SR & (1<<7))){
        nop(); //wait until not busy
    }
    while(!(SPI->SR & (1<<0))){
        nop(); //wait until receive buffer is not empty
    }
    registerValue = (SPI->DR);
    nop();
    return registerValue;
}

As a initial test I tried to read the DEVID register of the ADXL345 (0x00), it should return 229 as decimal value. And indeed, it did, this is my function to read a register:

void getValueFromRegister(uint8_t reg, uint8_t *val){
    uint8_t transmitValue = (0x80 | reg);
    uint8_t receivedValue = 0;

    GPIOA->ODR &= ~(1<<CS); //CS low
    SPITransmit(transmitValue); //write 'read' command
    delay_ms(10);
    receivedValue = SPIReceive();
    GPIOA->ODR |= (1<<CS); //CS high

    delay_ms(10);
    *val = receivedValue;
}

I also enabled the ADXL345 with this code:

void initADXL345(){
    //enable measurements
    GPIOA->ODR &= ~(1<<CS); //turn CS low
    SPITransmit(0x2D);
    SPITransmit(0x08);
    GPIOA->ODR |= (1<<CS); //turn CS high
    delay_ms(5);

    //set FULL_RES & 16g-Range
    GPIOA->ODR &= ~(1<<CS); //turn CS low
    SPITransmit(0x31);
    SPITransmit(0b00001011);
    GPIOA->ODR |= (1<<CS); //turn CS high
}

So the next logical step would be to read data from the data registers (0x32-0x37), so I did (x, y, z are global values of type int16_t):

void getXYZValues(){
    uint8_t x0,x1,y0,y1,z0,z1;
    getValueFromRegister(0x32, &x0);
    delay_ms(10);
    getValueFromRegister(0x33, &x1);
    delay_ms(10);
    getValueFromRegister(0x34, &y0);
    delay_ms(10);
    getValueFromRegister(0x35, &y1);
    delay_ms(10);
    getValueFromRegister(0x36, &z0);
    delay_ms(10);
    getValueFromRegister(0x37, &z1);

    x = ((x1<<8) | x0);
    y = ((y1<<8) | y0);
    z = ((z1<<8) | z0);
}

The problem now is:

I always get the value -6683 (decimal) for every axis! And these value isn't even changing if I move the sensor!

For gods sake, why is it so horrible to work with this sensor?

I thought about that maybe CPOL or CPHA is the problem but according to the datasheet they should both be enabled (as I did).

Any ideas, why this is not working? I am really frustrated and I try to get it to work for weeks (if I add the days from my first try with software SPI).


texts: Find the value of U by the means of superposition

texts:
I want to do that by superposition rule.

Firstly i need to short the E source and compute U0 in case of current divider formula?

So i will get u1 which is voltage loss when the voltage source is short
$$ U1=6mA\cdot \frac{2R}{2R+R0}$$
Then in second case i will use only E source.
Now i have to find total current in that circuit which is equal
$$ It=\frac{E}{2R+R0}$$
And then i just compute U2 which is voltage loss when we have our current source open
$$ U2=1mA\cdot 2kOhm$$
And my result is
$$ U0=U2+U1=5V $$
Am i right?


texts: charge controller question: disconnect pv with mppt from full battery

texts:
I'm creating a battery charging model with pv and a buck converter controlled via a P&O mppt algorithm. My charge controller currently disconnects the pv panel from the battery as the latter reaches a certain voltage level. As a result I get massive current oscillations on the input side of the buck and voltage oscillation on the output side. Also, when the panel is reconnected, there is a high current/voltage peak on the output side.

What the charge controller does is admittedly quite rudimentary: it just disconnects and connects the pv panel without altering the mppt algorithm. There are no dummy loads nor diodes preventing negative currents.

Now, I would like to ask what the charge controller should optimally do when the battery reaches its maximum charge. Should the mppt be switched off and the duty ratio of the buck be regulated to zero before disconnecting the panel? Should it be disconnected in the first place? Should I use a dummy load that connects to the buck when the battery is disconnected?

In order to mitigate the oscillations, I set the buck duty ratio D to zero when I disconnect the panel but the oscillations remain.

Clearly I'm just missing some basic knowledge on how a charge controller operates. I tried searching the forum and elsewhere on-line but didn't find what I was looking for. I'd greatly appreciate any insights.

Thanks!


texts: I'm a little confused about the standard SMD package sizes. Say I have picked some capacitors, and their package is 1005 (0402). Would this have the exact same footprint as a resistor or inducor with the same listed package size? I ask because I'm using Altium, and the generic PCB footprints libraries seem to be slightly different between the inductor and resistor footprint for a given package number.


texts: Prototype needs 3 different voltages (3.3, 4.0 and 5)

texts:
I have 3 components on my board that have different power requirements. They are as follows:
msp430fr2433 needs 3.3V (Active mode) draws 126uA/MHz. Clock freq is 8Mhz, so the draw will be around 1mA.
LCD screen needs 5V (Minimum 4.5V) 1mA (Max of 1.5mA)
LCD backlight needs 4.1V (Max 4.3V) 60mA
I was told to use 3 separate regulators on TI forums. I feel like there has to be a better way. After searching for a while I found the following:
https://www.digikey.com/en/products/detail/analog-devices-inc/LTC3256EMSE-PBF/6173775
It's expensive though at 8$. Couldn't find anything else. It's cheaper to buy 3 separate regulators than this. Any ideas?
Which way should I go to implement this efficiently?


texts:
I am using C compiler and PIC controllers.
I've been wondering about measuring the performance of the f/w code that we write. I have two versions of structures for the same code:

First one: using while

main()
  {..
   ..
  initialization;

  while(check for conditions)
  {...
  ..
  .
  }

}

Second one: Using sequential states, or State machines.

main()
    {..
     ..
    initialization;

    switch(state n)
    {...
    ..
    .
     }

    }

Well, my doubt is that whether I do either way, how will I measure which one is the best way to go forward?
I realized that the polling feature of the first method is often used in simple embedded systems. While the state machines of the second one is mostly used for single processor embedded systems.

How can I measure which firmware is best?
How can I monitor the statistics and related performance data?
Do compiler produces any valuable data to be checked, or is it debuggers that I must entrust?
What are the common tools available to measure the performance of a firmware?
Is it possible with a Debugger like Pickit3 /ICD3? I got a pickkit3 at hand.

I will be extremely grateful if you share your knowledge about dealing with firmwares and
clarifying my doubt.


texts: How can I do A/D conversion with isolation?

texts: I have to sense a voltage range of 0-25V dc and send to the ATMEGA 32 microcontroller. I want to use a voltage divider for sensing the voltage. But the problem is isolation is required between the microcontroller and the sensing side. For isolation I cant use optocoupler since the output of the optocoupler is not proportional to the input sensing side, other than using sensors any other ideas for isolation?


texts: Do DC/DC converters provide reverse polarity protection?

texts:
I plan on using a TPS63061 as DC/DC to get a steady 5V from 4xAA batteries. The data sheet says:

  8.3.4 Undervoltage Lockout
  An undervoltage lockout function prevents device start-up if the supply voltage on VIN is lower than approximately its threshold (see the Electrical Characteristics table). When in operation, the device automatically enters the shutdown mode if the voltage on VIN drops below the undervoltage lockout threshold. The device automatically restarts if the input voltage recovers to the minimum operating input voltage.

The Electrical Characteristics table states:

  UVLO Under voltage lockout threshold:
  Input voltage falling | min 1.8V | typ 1.9V | max 2.2V
  UVLO hysteresis:
  300 mV

Does this mean that the TPS63061 protects me from reverse polarity if I place my batteries in reversed order? Which would yield -6V which would be below 1.8V and hence the under voltage lockout function would protect me?

Or do I need an additional protection e.g. using a Schottky diode or MOSFET to avoid damage to the DC/DC and other components?


texts: What Resistor to use between Source and an IC

texts:
I'm trying to make a clock, and as part of that I need to power some IC's. To give a specific example I'm looking at the TI SN74HC163 4 bit counter. After some searching around, I found myself directed to this (basically Ohm's law) equation from the sacred texts:

The problems I'm facing are:

I'm not sure what to use for current in the equation (I'm that not good at reading datasheets and I'm not sure whether to use ±50 mA or one of the other numbers given to me in the MicroAmp range.)
Conceptually the equation doesn't make sense to me. If the Voltage drop  across a resistor depends on it's proportion of the total resistance of the
(series) circuit, then shouldn't I need to have the resistance of the IC? Apparently I don't, but in that case I don't understand how this works.


texts:
I'm looking for some chassis and cases to put my electronics projects in. My projects tend to involve at least one microcontroller and/or fpga. My boards are often very "verbose" and I put few major features on each board so I often end up with several boards. I would like an easy way to both reuse some of the boards across projects but also have a structured way to connect the boards, not just lay them out on my desk as I do now.

I would like something like this  except that it shouldn't cost me my first born. It doesn't have to be as big, but I would like something that can hold a handful of boards and have a "useful" backboard. It would be nice if uses standard VME connectors or something similar (even ISA would be useful). Hopefully each board be 100mmx160mm in size, but that's not critical either.

Also, does anyone have an alternate way of organizing the few boards that make up a project?


texts: How to work with LCD to display a sequence

texts:
If I want to display a sequence or any character that what are the steps. I have a LCD that is attached with this and I want to know that how can I use this LCD to display my name or number etc. I read some datasheets and documents.From there, I get that how LCD works ,their COM pins and segments pins.The thing that I am not getting is how to generate the segment value for a particular digit. I have attached a pdf file that is on which I have to work with. As a begineer in the field of software I want to display some sequences on the LCD.

Any new idea would be really appreciated

Thanks.


texts: Are regular fuses temperature sensitive?

texts: Are common fuses, like AT car fuses, temperature sensitive? Say a 12v 5A fast blow fuse, would it have any significant change in its reaction at 0ºF than it would at 100ºF? In either time to blow or current required to blow?


texts: Guru Meditation Error: Core 0 panic'ed (InstrFetchProhibited). Exception was unhandled. ?? ESP32 FreeRTOS Error

texts:
I was trying to learn FreeRTOS. This is my simple FreeRTOS code that I'm trying to run on my Esp32.

Code:

 #include <stdio.h>
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "sdkconfig.h"

 TaskHandle_t hello_task_handle = NULL;

 void hello_task(void *p){

     int count = 0;
     while (true){
         printf("%d: Hello Task", count++);
         vTaskDelay(1000/portTICK_PERIOD_MS);
     }
 }

 void app_main(){

     xTaskCreate(&hello_task, "hello_task", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY, &hello_task_handle);
     vTaskStartScheduler();

     while (true){

     }
 }

But I keep getting the following:

Error Output:

``ets Jun 8 2016 00:22:57

rst:0xc (SW_CPU_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)

configsip: 0, SPIWP:0xee

clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00

mode:DIO, clock div:2

load:0x3fff0018,len:4

load:0x3fff001c,len:6120

load:0x40078000,len:8816

ho 0 tail 12 room 4

load:0x40080400,len:6412

entry 0x40080748

␛[0;32mI (30) boot: ESP-IDF 3.30202.190627 2nd stage bootloader␛[0m

␛[0;32mI (31) boot: compile time 11:15:18␛[0m

␛[0;32mI (31) boot: Enabling RNG early entropy source...␛[0m

␛[0;32mI (36) boot: SPI Speed : 40MHz␛[0m

␛[0;32mI (40) boot: SPI Mode : DIO␛[0m

␛[0;32mI (44) boot: SPI Flash Size : 4MB␛[0m

␛[0;32mI (48) boot: Partition Table:␛[0m

␛[0;32mI (52) boot: ## Label Usage Type ST Offset Length␛[0m

␛[0;32mI (59) boot: 0 nvs WiFi data 01 02 00009000 00006000␛[0m

␛[0;32mI (67) boot: 1 phy_init RF data 01 01 0000f000 00001000␛[0m

␛[0;32mI (74) boot: 2 factory factory app 00 00 00010000 00100000␛[0m

␛[0;32mI (82) boot: End of partition table␛[0m

␛[0;32mI (86) esp_image: segment 0: paddr=0x00010020 vaddr=0x3f400020 size=0x06d9c ( 28060) map␛[0m

␛[0;32mI (104) esp_image: segment 1: paddr=0x00016dc4 vaddr=0x3ffbdb60 size=0x021e0 ( 8672) load␛[0m

␛[0;32mI (108) esp_image: segment 2: paddr=0x00018fac vaddr=0x40080000 size=0x00400 ( 1024) load␛[0m

␛[0;32mI (113) esp_image: segment 3: paddr=0x000193b4 vaddr=0x40080400 size=0x06c5c ( 27740) load␛[0m

␛[0;32mI (132) esp_image: segment 4: paddr=0x00020018 vaddr=0x400d0018 size=0x13e00 ( 81408) map␛[0m

␛[0;32mI (161) esp_image: segment 5: paddr=0x00033e20 vaddr=0x4008705c size=0x046d4 ( 18132) load␛[0m

␛[0;32mI (175) boot: Loaded app from partition at offset 0x10000␛[0m

␛[0;32mI (175) boot: Disabling RNG early entropy source...␛[0m

␛[0;32mI (175) cpu_start: Pro cpu up.␛[0m

␛[0;32mI (179) cpu_start: Starting app cpu, entry point is 0x40080f1c␛[0m

␛[0;32mI (170) cpu_start: App cpu up.␛[0m

␛[0;32mI (190) heap_init: Initializing. RAM available for dynamic allocation:␛[0m

␛[0;32mI (197) heap_init: At 3FFAE6E0 len 0000F480 (61 KiB): DRAM␛[0m

␛[0;32mI (203) heap_init: At 3FFC1130 len 0001EED0 (123 KiB): DRAM␛[0m

␛[0;32mI (209) heap_init: At 3FFE0440 len 00003AE0 (14 KiB): D/IRAM␛[0m

␛[0;32mI (215) heap_init: At 3FFE4350 len 0001BCB0 (111 KiB): D/IRAM␛[0m

␛[0;32mI (222) heap_init: At 4008B730 len 000148D0 (82 KiB): IRAM␛[0m

␛[0;32mI (228) cpu_start: Pro cpu start user code␛[0m

␛[0;32mI (246) cpu_start: Starting scheduler on PRO CPU.␛[0m

␛[0;32mI (0) cpu_start: Starting scheduler on APP CPU.␛[0m

Guru Meditation Error: Core 0 panic'ed (InstrFetchProhibited). Exception was unhandled.

Core 0 register dump:

PC : 0x800d0a02 PS : 0x00050033 A0 : 0x800d0a02 A1 : 0x3ffb1d30

A2 : 0x00000000 A3 : 0x7fffffff A4 : 0x3ffb3990 A5 : 0x454c4449

A6 : 0x3ffb0031 A7 : 0x3ffb2db8 A8 : 0x3ffbec08 A9 : 0x3ffb3e10

A10 : 0x00000000 A11 : 0x00000005 A12 : 0x00000300 A13 : 0x800867f0

A14 : 0x3ffb1db0 A15 : 0x00000000 SAR : 0x00000000 EXCCAUSE: 0x00000014

EXCVADDR: 0x800d0a00 LBEG : 0x00000000 LEND : 0x00000000 LCOUNT : 0x00000000

Backtrace: 0x400d0a02:0x3ffb1d30 0x400d09ff:0x00000000

Rebooting...


texts: What determines the maximum rotational speed of a hard disk drive?

texts:
Through my background research I understand that the limit on the rotation of a hdd is largely the product of heat and the specs of the physical disk, but I am puzzled by the round numbers advertised for speed.

In other words, why do speeds jump from 4200rpm to 5400rpm to 7200rpm and then 10000rpm? What is it about these numbers? Why not go from 5400rpm to 6600rpm? It seems like companies competing to be the fastest would be happy to advertise even incremental 100rpm bumps.


texts:
Anybody have experience with the range of these xbee modules? I reading about 10 kilometers:

http://diydrones.com/profiles/blogs/what-is-the-maximum-range-of-an-xbee-lets-find-out

But according to my previous research with 433mhz radio modules like these:

http://www.instructables.com/id/RF-315433-MHz-Transmitter-receiver-Module-and-Ardu/

cant even do 15 meters indoors with antenna. I want to make sure this xbee XB-24 will be able to do 10 meters indoors without an antenna. The 2 units separated only by a wood ceiling.

Thanks.


texts: Wiring an alarm to continually sound when activated

texts:
I'm working on a basic window-switch activated alarm that runs on 12v. When the window is opened, the window switch activates the alarm sounder.

The issue is if the window is immediately closed again, the alarm stops. What I'm asking is, how can I wire the sounder to either continually sound or sound for a certain amount of time, regardless of whether the window is shut again or not?

This project is a basic burglar alarm.


texts: Is there any disadvantage with transmitting the same excitation signal to several resolvers (basically rotating transformers)?

texts:
I am considering sending the same excitation signal to multiple resolvers (i.e. transformers of which the secondary rotates with respect to the primary) used as angle sensors in the joints of a robotic arm. As long as the source is capable of driving these loads (in fact, the inductance seen by the transmitter would be divided by the number of sensors, since the excitation windings would be in parallel), I don't see any issue with this but perhaps I am not seeing the entire picture. Accuracy is highly important.

The transmitter will be custom-made, not bought.

I'm considering an excitation signal around 12V in amplitude, 0.5 turn ratio with secondary, and 1kHz in frequency.

What do you think?

I'm willing to simulate on simscape any schematic you may use to illustrate what you say.