texts: Which of these diagrams should be in the copper side of pcb?

texts: I'm trying a DIY PCB using toner transfer method then etching but I am confused with the diagram below. I thought the top trace goes to the copper board but there's this bottom trace which shows solder side. Which of the two goes to the copper side? Any help would be greatly appreciated thanks.


texts:
looking for some help regarding switching regulators for a personal robot project.

The problem:

I have: two 18v 4.5Ah batteries (which when fully charged are actually more like 21v)

I need:  5v/1A for a USB hub, 12v/2A for a Udoo, and 30v-35v/2A for some stepper controllers.

Ideally, I'd just use three switching regulators to provide the required voltages at 90%ish efficiency, but I'm having trouble finding any that would cope with the 42v of the batteries in series.

What I'd like to do is add something like a 15v regulator to each battery and combine the outputs of the two regulators in series to make 30v. This would power the steppers and I could then add two further regulators to step down from 30v to 12v and 5v for the rest.

My question is: can this be done?!


texts:
I´m working on a small project that consists of a fuel sensor controlled by an arduino that sends data to a raspberry with an HTTP request on local wifi. The raspberry listens to other sensors like voltage and current which are on another arduino.

The system works pretty good, but now it is time to make it more "industrial".I have little experience on how to move from a prototype like the one I mentioned to something that fits the industry standards. What things do I need to keep in mind (Voltages, security standards..) to make this project something that can be used in real life? What can I replace the arduino with? Is the raspi still viable for something working on an industry?

Just to give a little bit of context, the system is expected to monitor a site where there is a motor and a fuel tank on the outdoors. The raspi sends it to a server saves all the data on a DB.

Any suggestions are highly appreciated


texts: Circuit design for short-circuting outputs when needed

texts:
I am working with two sensors with 4 pin as output.
My question is simple: I want to make circuit that allows me to short circuit the output of either one of the sensors individually when needed.

I am considering using quad 1:2 demux (AGD774a) and shorting either the pins on channel B together while measuring with channel A and vice versa.
So when I want the channel for normal measurement I will use channel A and when I want output of sensor shorted I change the channel of the switch.

So, my main question is whether using a demux to solve the requirement is a wise choice or there is some other way it can be achieved.

Notes:

The sensor is an ultrasonic transducer which produces only millivolt level outputs.

In use the sensor is placed in a heating chamber to increase its temperature.
When the temperature of the transducer is varied, it produces spurious temperature-change related voltages.
After heating we need to short the output pins to release all the residual voltage.
The charge itself is small.

May be I can do a worst case calculations and attach a resistance as well with it.
The voltage drop is small - in the mV range.
I do not think that an electromechanical relay is required.
The sensor will not be connected to Micro-Controller.
Shorting is needed to discharge the piezo in the sensor which occurs when the temperature is changed.


texts:
AC current is sine wave with 60 hz frequency - how is this helpful in understanding electricity and transmission? Does the sine wave progress through electric wire or stands static and oscillates?
when electricity enters the house through hot wire and is consumed by electronics, the neutral wire takes the unconsumed electrons back to sub station. Why is this simply grounded? is it not wasting electricity? can't the electrons be harnessed?


texts: Noise caused by improper decoupling of VDD pin

texts:
I have posed a question, "Function run in MCU generate noise to the analog circuit", before but at that time the question was not detailed enough. After several days` of testing, the problem is now more specific.

When I run a function with 600 Hz frequency, I can observe a set of noise (600 Hz, 1200 Hz, 1800 Hz, etc.). Here is the frequency spectrum:

After some tests, I think it is due to the improper decoupling of the VDD of the microcontroller. But I am not sure. I did another test. I found that when the capacitors (inside red circles) changes their value from 0.1 µF to 0.01 µF, the noise decreases.

And the noise after the change:

My question is:

Why would the noise decrease after the change? Is it due to the improper decoupling of the microcontroller? (but 0.1 µF is recommended in the STM32F4 datasheet).

Here is the PCB of those pins and capacitors:


texts: When trying to program Attiny13 with simple blink program avrdude shows "target doesn't answer"

texts:
avrdude is giving me this error message when trying to program:

  avrdude.exe: error: programm enable: target doesn't answer.
  avrdude.exe: initialization failed, rc=-1 Double check connections and try again, or use -F to override this check.

I was trying to program this code when avrdude gave me the error message:

#define F_CPU 8000000L
#define PB3 3

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

int main(void)
{

    DDRB = 0xFF;
    PORTB = 0b00000000;

    while(1)
    {
        PORTB = 0b000001000;
        _delay_ms(600);
        PORTB = 0b000000000;
        _delay_ms(600);
    }

    return 0;
}


texts: Do I need a grounded electrical outlet for a laptop and computer monitor?

texts:
I am currently setup in a room with (2 pin) non grounded outlets (Canada).  I am considering setting up my laptop and monitor.  What risks would I be taking by not using grounded outlets with these items?

My main concern is about harmful electric shocks, or starting a fire.

Both products have the 3rd pin on their plugs

laptop: https://www.amazon.ca/GL62M-7RD-1407-Performance-i5-7300HQ-SteelSeries/dp/B072QT88DG

monitor:https://www.dell.com/en-ca/shop/dell-27-gaming-monitor-s2716dg/apd/210-agjr/monitors-monitor-accessories


texts:
Has anyone had much experience with the Pololu Robots

Which are the coolest? what do you recommend i get?

I'd like to hear about some cool projects with these Robots  :)


texts: How to determine the lowest bound of current sensor sensitivity?

texts:
I would like to build current logger using Arduino. I am having hard time finding out and understanding the lowest bounds of current sensor sensitivity.
The following link states sensitivity this way "66 to 185 mV/A output sensitivity". Does it mean that 1 Amp will generate 66 mV? Does it mean that the lowest I can go is 1/66 Amp, which will generate 1 mV? Now it brings question what Voltage can Arduino read? If Arduino can read up to 1 uV, does it mean that I can go even lower with the above sense like 1/(66*1000) Amp?
Overall I need fairly sensitive sensor 1 mA or less if possible. Could somebody recommend something?
P.S. I am very new to all of this.
P.P.S. Here is a datasheet


texts:
While working on a project recently, I noticed that Digi-key has a product category "Terminals - Turret Connectors". I've never seen connectors like this before, and they don't look like any kind of contact I've seen before. What does the mating connector look like? I can't envision any mating contact that makes any sense for these.

On top of that, they look like they have to be individually machined, which can't be a cost-effective process.


texts: Node analysis with voltage source in matrix form

texts:
simulate this circuit – Schematic created using CircuitLab

Can you please check if my reasoning is correct?

The sum of currents leaving node k is:
$$ I_k = \sum_{i = 0}^{n} I_{ki} = \sum_{i = 0}^{n} G_{ki}(V_k - V_i)$$
Assuming the system is linear:
$$ I_k = \sum_{i = 0 (i \neq k)}^{ n} G_{ki} V_k - \sum_{i = 1 ( i \neq k)}^{n} G_{ki}V_i
= G_{kk}V_k - \sum_{i = 1 ( i \neq k)}^{n} G_{ki} V_i $$
where:
$$G_{kk} = \sum_{i = 0 (i \neq k)}^{n} G_{ki} $$
then we have:
$$I_n = -G_{n1}V_1 - G_{n2} ... + G_{nn}V_n $$
which in matrix form gives:
$$\begin{bmatrix}I_1 \\ I_2 \\. \\ . \\ . \\ I_n\end{bmatrix} =
\begin{bmatrix} G_{11}& -G_{12}& -G_{13} ... &-G_{1n} \\
-G_{21}& G_{22}& -G_{23} ... &-G_{2n} \\
.&.&.&. \\
.&.&.&. \\
.&.&.&. \\
-G_{n1}& -G_{n2}& -G_{n3} ... &G_{nn}
\end{bmatrix}\begin{bmatrix}V_1 \\ V_2 \\. \\ . \\ . \\ V_n\end{bmatrix}$$
In case there is an ideal voltage source connected between a node and the reference, then the voltage of that node is equal to the EMF of that voltage source. So in matrix form we have(if for example node 1 was connected to an ideal voltage source):
$$\begin{bmatrix}E_1 \\ I_2 \\. \\ . \\ . \\ I_n\end{bmatrix} =
\begin{bmatrix} 1& 0& 0 ... &0 \\
-G_{21}& G_{22}& -G_{23} ... &-G_{2n} \\
.&.&.&. \\
.&.&.&. \\
.&.&.&. \\
-G_{n1}& -G_{n2}& -G_{n3} ... &G_{nn}
\end{bmatrix}\begin{bmatrix}V_1 \\ V_2 \\. \\ . \\ . \\ V_n\end{bmatrix}$$
However, if we have an ideal voltage source between two nodes (neither of them being the reference), for example between nodes 1 and 3 we have E, then we have:
$$\begin{bmatrix}I_1 \\ I_2 \\E \\ . \\ . \\ I_n\end{bmatrix} =
\begin{bmatrix} G_{11}& -G_{12}& -G_{13} ... &-G_{1n} \\
-G_{21}& G_{22}& -G_{23} ... &-G_{2n} \\
-1&0&1&0 \\
.&.&.&. \\
.&.&.&. \\
-G_{n1}& -G_{n2}& -G_{n3} ... &G_{nn}
\end{bmatrix}\begin{bmatrix}V_1 \\ V_2 \\. \\ . \\ . \\ V_n\end{bmatrix}$$
My professor claimed that the third case had a more elegant solution which included adding an imaginary node and a new current, but I cannot understand what he meant, any insight?


texts:
I am designing a Raspberry Pi hat that needs to be able to accept inputs from 3 different water meters. Two of the inputs are 4-20mA signals, the third input being a pulse signal. At the top I have two powered 4-20mA loops powered by 24VDC. These loops are connected to a 16 bit ADC (A0/A1) which is connected to the Raspberry Pi through the I2C communication ports. There are 200ohm resistors for each of the loops. Both 4-20mA output modules have a positive and negative wire as well as a ground wired to the water meter.

1.) Will a 24VDC power supply be enough to power both 4-20mA loops?

2.) Is 200 ohms for the resistors still sufficient?

On the bottom right, I have the pulse signal terminal. I have measured the pulse signal to be 24VDC. Because this is a pulse, I need to debounce it which I think I can do using a hardware debounce with a capacitor. The Pulse is then connected to pin 23 on the Raspberry Pi.

3.) Will this design of the hardware debounce even work? What problems are present in its design?

4.) How do I figure out what size capacitor I will need?

5.) Overall is the design sufficient for what I need?

I don't know much about electronics, so any help would be much appreciated.


texts: FUSB302 - Two devices, transmission between them

texts:
I have controller device with a FUSB302 Programmable USB Type-C Controller with PD for power detection for charge battery.
I want to make a subdevice to emulate my own hardware. I know that FUSB302 can communicate by CC1/2 pins. After connect USB to controller, communication between the FUSB302 systems would take place, to detect my own device.
The questions are:

How can I emulate my device on the FUSB302? What registers to set?
How to set my controller to detect chargers as before, but also my own device?

The library I use is PD_Micro, a "ATMega32U4 Arduino board with USB-C PD Power Delivery and PPS".


texts: I want to measure the battery voltage while it is charging, 12v li_ion battery here I am using and a source supply is used to charge a battery and providing supply to the load(like inverter whenever supply turned off, load uses the battery power ). a multimeter is used check the battery voltage that time it showing source voltage if I remove the source and checked that time it showing correct battery voltage how I measure battery voltage when the source is connected.


texts:
I'm just getting started with PIC processors, driven mainly by a shortage of the simpler PICAXE from my local retailer. My question is, how do I read the length of a PWM pulse on a certain input pin (analogous to the PULSIN command on PICAXEs). I'm using the MPLab IDE, and the specific PIC in question is the 12F683.
Secondly, (sorry to combine two questions into one), are there libraries out there that contain 'common' functions (PWM output, i2c support and the like)? Google's turning up dry-ish, but it seems to me that such libraries have to be out there, somewhere.... Thanks for any help!

EDIT: the language is C, and the PWM signal is the output from a RC reciever intended for a servo, so, it is a 1-2 ms high pulse every 20 ms (if I understand that correctly)


texts:
I'm looking to build an antenna to research the 5-500 Hz range.  I already had decent success with just a simple square loop 1.5 ft per side (air core), about 12 turns. Despite having an estimated resonant freq. approx. 4 MHz, inside the house, it does easily pick up all the odd harmonics of the power line frequency. But weaker signals are extremely faint and below 60 Hz the spectrogram is all noise.

I will be using a ferrite rod for an improved loop antenna (mu-metal is too expensive for me).  I found an excellent tutorial here on building an induction coil antenna (http://www.vlf.it/romero3/ics101.html) that rivals far more expensive commercial antennas.  I will be constructing a "poorer-man's version" of his design.

Can anyone recommend (or, even better, supply a schematic for) a simple but reasonably effective pre-amp for my "poorer-man's version"?  The Romero design has a 3-stage pre-amp + 1-stage supply and I'm looking for something simpler, even if performance is less. My main concern is decent dynamic range in the 5-200 Hz segment (areas above this seem easier), keeping in mind the power line harmonics can be quite high.


texts: How to charge a lipo battery inline with load

texts:
How do you charge a lipo battery while it's still connected to it's load (e.g. like all modern mobile consumer electronics) using an off the shelf lipo charger?

I have an Accucell S60 battery charger and a 2S 4000mAh 25C Lipo battery. Both are designed for high-current RC cars where you typically remove the battery when you're done, but for my project, I want to embed and wire the battery so it doesn't need to be removed, nor the load completely turned off. How can I do this with the minimal extra wiring?

The battery has the standard HXT4mm discharge plug and JST-XH balance plug.

When charging, my application's load will be minimal and will only require about 500mA of current, so it won't be drastically stressing the battery. If possible, I do not want to have to introduce a separate power circuit to disconnect the load and power it separately.

Options I've considered are:

Charge solely through the balance plug, keeping the discharge plug connected to the load. Comments here suggest that this charger doesn't directly support that, but comments here suggest I'd need a parallel balance extension cable to connect the mains charge lead of the charger to the first and last pins of the balance plug.
Create a special adapter to wire the charger in parallel with the load via the discharge plug. I think this is essentially what option #1 does.

Is this feasible? Are there other options I'm not considering?


texts:
I'm looking to control a 12v/2A circuit from a Raspberry Pi but I'm a little lost on what I need to get to operate it.

I was looking at the following but with a IRLZ44NPBF transistor and a in4004 diode from CPC as I can't find the right PN2222 or in4003 in the UK.

Would I be along the right lines?


texts: Inverting switching regulator with -80V DC output

texts: I need to design an inverting regulator with a +5V DC input and a -80V DC output. The maximum output current will only be 10mA. I cannot find any commercial switching regulators with -80V output specification. Can regulators that have -48V outputs be reconfigured to do -80V or should I continue to look for regulators that state that they can do -80V.


texts: Using LiPo cells without a protection circuit

texts:
I designed a PCB to provide the power circuit for my robot's servos. This has a LiPo battery protection IC (undervoltage/overvoltage) and a voltage regulator IC. I sent this PCB in to be manufactured, and went to order the parts...

Only to find out noone sells the IC (S-8253) I planned to use for protection. Seiko Instruments does not list this as out of production/outdated, and my quick initial search did show the IC on Digikey's website, but I did not apparently notice that it is not stocked. And I cannot buy 3000 chips ;)

Anyway, the PCBs will be here soon, and I would like to do some work on my robot during this Xmas break. How bad will it be if I bypass the protection circuit for the time being? I plan to charge my LiPo using a proper charger, which I would hope balances the cells anyways... But I have no way to control even discharge.

Also, if anyone has any suggestions for undervoltage/overcurrent 2-4 cell protection ICs that can be hand soldered, I'd appreciate it :)

Thanks!


texts: Does a discharging capacitor in an AC circuit add additional voltage to circuit?

texts:
In an RC circuit with an ac voltage source, after the capacitor becomes charged and then the sign of the ac voltage flips, does the discharging capacitor add additional voltage to the circuit compared to when the capacitor had no charge on it?

Thanks


texts:
Is there a 74HCT03 equivalent I can just replace  "as is"?
Of course, it will be better to buy the same exact chip reference but is it always the case?

Many chips are equivalents pin-to-pin, right? If so, (in limits of current & voltages of course)...is this possible in most cases or is this always a stupid idea?

Thanks.


texts: Error while trying to program my ATmega16A with extreme burner

texts:
Whenever I want to burn the hex file on my chip, the following error message always appears:

Power On Failed
Cannot communicate with target chip

The programmer I am using is AVR USB programmer, from ABLab Solutions. The software I am using for program burn is extreme Burner AVR.
I don't think this is a problem with the driver because it says it has found an USBasp on USB port. There was an option to select the chip model, where I selected ATmega16 (because 16A) was not there. How can I solve my problem?
EDIT: The picture of the circuit: I used Zener for just-in-case voltage fluctuation.

simulate this circuit – Schematic created using CircuitLab


texts:
There is this rule of thumb to estimate the required bandwidth of a digital signal by its rise time:
$$
\text{f}_{\text{knee}} = \frac{0.5}{\text{t}_{rise}}
$$

This knee frequency is described in "High Speed Digital Design: A Handbook of Black Magic" as the point at which the spectrum of a real signal would show a steep fall off.
I simulated this, first with python and then LTspice, and expected that the spectrum would be monotonously decrease above the knee frequency.
Both simulations of a 100 MHz square wave showed the following:

The green spectrum has the steepest rise time (10 ps), whilst blue has a lower (100 ps) and red the lowest (1000 ps).
One can see that the spectrum of blue shows a steep fall off somewhere around the knee frequency (light blue shows knee frequency), but then rise again (black arrows).
I tried different windows types and widths in LTspice. The overall shape remained the same.

Can this be explained mathematically or is this not part of the theory, but an artifact from the FFT?

LTspice circuit


texts: Why does width of depletion layer increases and electric field decreases if doping decreases for diode?

texts: Also, why does width of depletion layer decreases and electric field increases if doping increases


texts: Battery Discharged - But Potential difference exists without any current flow

texts:
My below question is regarding batteries.
I have a USB charger and a mobile battery (Li-ion battery).
So, my mobile battery percentage has dropped to 0%.
So, what I do now - Take the USB Charger. Plug it in the wall socket and measured the output voltage of the USB Charged. I measured it to be 5V.
But once I connected it to my mobile battery, I measured the voltage in the USB Line and the current through it. (Ignored the D+ and D- lines)
I measured the voltage to be around 4.6V and current to be 0.92A.
My questions :

When my mobile battery voltage is showing 0%, but the voltage between my mobile battery terminals in 4.6V. I have read that it stops around that voltage because some chemical reactions cannot occur. But My fundamental question is - Even while having 4.6V, why cannot my battery provide current to the mobile and keep it working? Like, the battery has potential difference but is not providing any current? Why is that?

(This is not specific to the only Li-ion batteries. I have seen 12V Lead acid batteries also not providing current even though the voltage across the terminals is around 11V? Why is this happening even though they have the potential difference? Like potential difference should cause current flow right? If potential difference is present, why is the current not flowing from the battery)

My USB charger was showing 5V before connecting to the mobile battery. But once I connect the charger to the mobile battery, the voltage on the line is showing 4.6V and the current is around 0.92A?
The output of the USB charger is supposed to be constant regardless of the load current, right? If not, then it is not a good regulator or charger, right?
My question here - Why is the voltage dropping to 4.6V instead of being 5V, when connected to the mobile battery and what determines the current value to be 0.92A?

My USB Battery charger rating is 5V & 1A. So, shouldn't it output 5V & 1A instead of 4.6V and 0.92A?
Please help me to clear my misunderstanding the about two concepts of charging batteries


texts:
I would like to decode a signal from a radio clock source, using an off the shelf receiver, and a microprocessor.

The output of the receiver is a digital level which encodes either carrier on or carrier off from the transmitted signal.

The signal itself is encoded over a period of 1 minute with approx 2 bits per second, each bit being 100mS wide. (The signal is the NPL time signal, formally MSF Rugby)

It occured to me that the clock of my microprocessor will not be precise and that additionally the signal would be subject to noise and that my sampling approach should really take this into account.

I could...

(1) have an interrupt on a falling/rising edges

By detecting edges I could then time the width of the current value using the local clock.

(2) sample at period intervals, say every 20mS

If I sampled every 20mS I would get 5 samples per pulse

Neither of these approaches feel quite right.  The first would cause a large number of interrupts if there was a burst of noise. The second seems like it could accumulate errors due to the local clock drift.

Any suggestions?

Thanks in advance


texts: How a high Earth to Neutral voltage affects electronic equipment like L2 or L3 switches?

texts: We have lot of communication equipment installed recently in our organisation. From then, lot of pressure on us to reduce Earth to Neutral voltage at the input of our communication equipment like L2 or L3 switches which are frequently failing due to high ENV. Can anyone explain how it really affects the equipment performance, please?


texts: We all know that if we put a dielectric inside, the voltage lowers and capacitance increases. Yet, it lowers the energy density. If capacitance increases, then more charge is stored and so its like havin more energy stored. But experiment shows that energy density and potential electric energy decreases. Why is that?


texts: EtherCAT topology and timing constraint question

texts: I'm trying to understand how EtherCAT works.  The Wikipedia page says that data is processed as the packet passes through the device.  Does this mean devices must be linked in a string formation?  What if processing of a packet where to take longer than the time the packet takes to pass through the device -- what does it do then?


texts: Could my Cell Phone Battery be degrading?

texts:
I've noticed that if I recharge my cell phone battery to 100%, then take it out, and put it back in and put the phone back on charging, it resumes charging the battery and continues to do this for upto 30 mins, despite having just received a 'battery full' message about 30 minutes ago.

Why does this happen? Is this normal or does this indicate that the battery is degrading?

It is a Li-Ion battery.


texts: Where can I find IC packages list wich used in BSDL files?

texts:
I try to read a BSDL file. For example I take this. Then I change EQFP144 to TFBGA296 in this place:

attribute PIN_MAP of MAX_10_10M02SCE144 : entity is PHYSICAL_PIN_MAP;
constant EQFP144 : PIN_MAP_STRING :=
--I/O Pins

After this I load the BSDL into the TopJTAG Probe. The TopJTAG Probe read the pin list successfuly but (of course) can not show a package of IC.

The question is where I can find list of constants like "EQFP144"? I try to find this list in the std_1149_1_2001 (Appendix B) but there is no such constants.


texts:
My original question was:

  I've a 8 bit data with only 3 bit used, for example:

  0110 0001

  Where 0 indicate unused bit that are always set to 0 and 1 indicate
  bits that change.

  I want to convert this 0110 0001 8 bit to 3 bit that indicate this 3
  used bits.

  For example

  0110 0001 --> 111

  0010 0001 --> 011

  0000 0000 --> 000

  0100 0001 --> 101

  How I can do that with minimal operations?

I had this answer:

a = 0110 0001;

data = ((a >> 4) & 6) | (a & 1)

But before this answer I used this method:

a = 0110 0001;

if(a&0x01)
 data = data + 1;
if(a&0x20)
 data = data + 2;
if(a&0x40)
 data = data + 4;

I want to ask which is more efficient for a MCU an require less clock cycle to perform. (I know that depend on MCU, but I'm asking in general way)


texts: Does something like a "reverse jumper wire" exist?

texts: All these kits you can buy for arduino come with "jumper wires" which are great for connecting  a pin on the arduino to a breadboard. But "pin" on arduino is the wrong word since it's a female part. The "jumper wires" are male on both sides. What about the times where you want to connect a pin from say, the Motor Shield to some other pin? I would need a female to female jumper wire. Do those exist?


texts: are amplifier and attentuator bascially of the similiar function?

texts: I just got a very old function generator (I can't even tell the manufacture and the model number) to produce sine wave. I open it and see a big module label video amplifier. The function generator come with a digital switch to choose different level of attenuation. I look everywhere inside and didn't see any module for attenuation. I wonder if the amplifier is really for built to attenuate the signal? Basically are amplifier and attenuator of similar circuit design?


texts: DIY simple line out converter for "floating ground" car head unit?

texts:
On a 25W max power (10V p2p @ 4ohms) balanced (push-pull) high level output factory car audio head unit from which I need to feed a mono amplifier (for subwoofer) that only has an unbalanced line level input (0.15V-3V @ 10kohms), should I make my voltage divider to match the amps' input impedance or simply give it a 1kohms output impedance to make it a little more "universal"?

I want to bring the signal down to 2V p2p so I could either use 20k/10k or 3.6k/1k (or even lower) then go through a 10uF DC filtering cap.  Which would be better practice?


texts:
Does anyone know if there is a component or a solution for creating a switchable polarizing film using DC-power? (i.e. a film/glass/substrate/etc that can be switched between a polarizing and a non-polarizing state).

Since this functionality is included in every LCD-screen, I think it has to be possible. The closest solution I can find is smart glass, but they require AC according to my understanding


texts: Embedded hardware from software developer point of view

texts: for the first time I have been facing a task to develop software for a given embedded hardware (Xilinx Zynq 7000 - datasheet) from scratch. The software which I am going to develop will control electric drive of an electromobile. I have been looking for how to proceed in this situation. What is necessary to know about the hardware platform from the software developer point of view before starting coding? What is the appropriate sequence for studying individual features of new hardware? Thanks for any suggestions.


texts: Designing an effective power supply for embedded products

texts:
I'm currently designing several embedded microcontroller products to be powered from a wall outlet. I plan to use wall-wart power supplies to give an input of approximately 5-9V DC but I want the input of my device to work at up to 30V just for the sake of compatibility and ease of use. The output of this power supply circuit should be 3.3V at about 500 mA maximum. I also want reverse voltage protection in case a user plugs in a barrel jack with center-negative terminals. Below is my design. I used a PTC fuse to prevent short circuit/over-current issues, and a P-channel MOSFET to prevent reverse polarity from reaching the switching regulator. The Zener diode allows for high input voltages to not fry the MOSFET.

My main questions are: Will this switching regulator work with the P-channel MOSFET protecting the Vin pin? Are any of my part choices obviously bad? Are there any obvious mistakes that will prevent this from working?

Note: Some of these parts are found on LCSC just because of their low price & integration with the PCB service I use, in case you can't find the mfg. part number anywhere.

EDIT: I have modified my design to prevent inrush current above approximately 15-25A.


texts:
This teardown of a personal weather station shows an LED which is apparently used for detection of carbon dioxide with an accuracy of +/-5% within 0-5000ppm:

All the commercially  available carbon dioxide sensors I've found retail for above 100USD, so a low-power, low-cost sensor like this is appealing for IOT sensing (eg greenhouse monitoring). However, I haven't been able to find any information on this strange dome-shaped LED.

Another view:

The teardown says the LED is an infrared emitter/receiver pair: in the enclosure, it is pointed at a white surface, and it measures how much IR light is reflected from the white surface to calculate the CO2. This paper implies the sensor is an NDIR LED, and that its accuracy varies linearly with temperature, but doesn't go into specifics, and searching for NDIR LEDs shows expensive modules with waveguides.

Where could I find an LED like this? What specifications should I look for in an LED (eg spectrum, dome)?

Why haven't other companies done this, if it's so cheap and good?


texts:
Can you please help me on how to create a Verilog code for frequency divider circuit that can generate 50Hz clock signal out of 50MHz signal using 16 bit synchronous counter. I have tried to do it, but it didn't work!

module divier_16 (clk_in, clk_out);

input clk_in;
wire w;
wire [0:15]temp;
output clk_out;
count_16 c1 (clk_in, w);
count_16 c2 (w, temp);

assign clk_out= temp[6];


texts: RF ferrite core inductor airgap magnetic field calculation

texts:
I was interested which formula I could apply to calculate the maximum field strength in an airgap located within an ferrite core, in my particular case I am looking at a "binocular" type wideband transformer/inductor core.
My intent is to use the core as an inductor with a single coil driven with Rf frequency and to obtain a flux within the airgap.
For reference please see the attached picture.
Would it be true that for a fixed turns count and amperage in order to increase the field strength within the airgap , I could make the part of the core that has the airgap thinner as this would concentrate the flux in less area? (assuming the flux with respect to area isn't too much to saturate the core at that part)
PS. I suppose the field strength in the airgap would vary also based on the driving RF frequency since the impedance of the inductor would change and so would the amperage for a fixed voltage?
My intention is to have as wide of a frequency range as possible starting from few Mhz up to as far as the ferrite can go , possibly 1-2 Ghz, although I read of some ferrites being able to function up to 20Ghz.


texts:
I connected a 50 ohm function generator to an oscilloscope set to have an input impedance of 1 MOhm. I set the generator to 0.5Vpp and saw a 1Vpp signal on the oscilloscope. The generator display is set for a 50 ohm load, so this all makes sense so far.

Then, I switched the oscilloscope to 50 ohm impedance, and I was expecting to see a 0.5Vpp signal, but I got no output at all. The scope has 10:1 probes and the input is rated for < 5 Vrms at 50 ohms. The current through the generator would be 10 mApp for a 50 ohm load, which it should be able to handle. There is no external circuitry. Function generator is HP33120A and scope is RTM2034.

So the question is, why does setting the oscilloscope to 50 ohms completely kill my signal?


texts: How can I find the X nature from this circuit?

texts:
In one question from my university exam, it was given this circuit:

The component X can be a capacitor, inductor or a resistor.

where all components values are unknown, less R2, it's equal 1kΩ.
The question has given  me this transfer function of output current io(it is been illustrated in the figure above):

The first thing I thought was analyse the transfer function at two extremes, low frequency and high frequency, so I found these expressions:

My objective was analyse, if the  X current(ix(t)) increases or decreases in these two extremes and then I'd have an idea about impedance and finally know the X nature. But I found a problem, I don't have any idea about the output frequency, consequently I don't know the output phase, if the output current increases or decreases and then I don't know how to find out the X nature. Could someone give me an idea how to solve this problem??


texts:
As per the title - How do i choose a Solar Panel?

What are the criteria (Watt, Voltage, Technology etc) that I need to take into considerations when I choose a suitable solar panel for my project?


texts:
I am looking for a DC to DC boost converter constant current with very low  switching frequency to pass EMC.

Vin- 12V
Vout- 36V, 100mA.

Any suitable device for my above application?


texts: Switching regulator not suppressing variance in input?

texts:
I am having a little problem with my switching regulator, based on a AP65211A and here is my schematic:

Parts:

Ref Value   Digikey Part#
C6  10uF    1276-6455-1-ND
C7  1000uF  399-6082-ND
R2  100k    RMCF0402JT100KCT-ND
C8  1 uF    1276-1102-1-ND
L1  6.8uH   587-3143-1-ND
R3  75k     RMCF0402JT75K0CT-ND
R4  78.7k   RC0402FR-0778K7L
R5  14.7k   YAG2984CT-ND
C9  22uF    1276-6780-1-ND
C10 220uF   490-13970-1-ND
C11 470uF   P5141-ND

It actually works great overall when plugged into a decent bench PSU and can deliver 2 amps to a test load, without the voltage dropping out at all.

The problem is when it is connected to almost any 12V wall adapter, with any voltage ripple.

Here is the best wall adapter I have been able to find (after buying many trying to find the most stable one). This is the input (12V) and output (5V) when hooked up to my switching supply, under no load:

Then with a 5 ohm load:

Added more and more capacitance to the input or output doesn't seem to affect it. Any ideas?

Right now, I do not feel comfortable connecting this to a microcontroller or anything, because the voltage spikes would definitely fry them.

Thanks.

Edit: Here is my KiCad Project, the entire project will be open sourced at some point. It is a controller for a saltwater fish tank: https://www.dropbox.com/s/n5knjkvoevhnout/ATO_CHANGE_CONTROLLER_V3.7z?dl=0

Edit: Here is another image using the math function to create a differential measurement:

They all match perfectly with the input supply (even when not connected to my switching circuit).

If I power the 12V rail from a bench power supply (Circuit Test PSA-2530D) this is what I get:

No Load:

Loaded:


texts: This model has the symbol, shown below. I cannot locate it in the Simulink tools. Can someone help me to identify this part?


texts: Say I have an ideal situation (good quality functioning power source and components) - 12V source and 3V (each) LEDs. Can I wire these 5 LEDs in series to the 12V source without a series resistor and expect that 4 of them would lit strong and one dim (or this one not lit at all), or all would light up dimmed ? Without burn, and etc as expected for an over voltage situation  - like wire 1 3v led to a 4V source  and etc.


texts: Bus tapping in Xilinx ISE for 8 bit to 16 bit conversion

texts:
I have a processing unit which is controlled by a sequencer/control unit. The agenda of this processing unit is to multiply 2 numbers using 8 BIT registers using the bit shift and add method.

Once the registers propagate the data in them to the 16 bit adder, I have to convert the 8 BIT values to 16 bits.

The input bus has to be 8 bits wide and the bus widths have to be set in the ISE schematic creator. I'm having issues trying to understand the need for bus tapping and how to use it to create a 16BIT to 8 BIT converter.

My questions:

How do I get the bus widths rite? Conversion?
How do I extract the LSB from the REG SR8CLED?


texts: Required Power Supply Driver for Peltier Module TEC12715?

texts: I am making a Mini-Air conditioner based on Peltier TEC12715. I'm going to use 10 peltier elements for better cooling. 1 peltier module requires: Umax(V):15.4 Imax(A):15 Max power consumption (watt):231 Watt . How much power supply is required to run all 10 Peltier Module. Which Power supply driver(AC to DC) should i pick?


texts: How do you find Fourier series coefficients for some weird waveform?

texts:
The formulae for the Fourier series coefficients contain f(x), e.g.

$$ b_n = \frac 1\pi \int_{-\pi}^\pi f(x)sin(nx)dx $$

But if I don't know what f(x) is, e.g.

or

then how can I get the coefficients?


texts: Confusion about dependent current source

texts: This is just a solved problem from a book on circuit analysis (Hayt), but I got a little confused on the voltage drop across the 2K resistor. This confusion might be about dependent sources. Why did he write the current as a result of only the current source and ignored the voltage source? Why not R*(Vx/4000 - I) where I is the current resulted from the voltage source? This question could be generalized to: dependent sources takes account of the whole circuit? What I mean by that is, this function (Vx/4000) takes account of the whole network, so the current in that wire will always be that of the function regardless of the rest of the circuit? Appreciate any insight.


texts: Average resistance of MOSFET output characteristics

texts:
Suppose we calculate resistance at two points in a MOSFET output characteristics,
For example: Vgs is at 5v. At Vds=5V Id=10uA and Vds=2.5V Id=9.3uA.

To determine the equivalent resistor of the tansistor, what should i do?


texts: Decoupling feedback for testing of PWM controller IC for SMPS

texts:
I am trying to test an SMPS controller IC (like KA3882) by isolating the controller from the PWM FET circuit and de-coupling the SMPS output (to optocoupler and the feedback pin of the controller).
By applying the required feedback voltage to the Vfb pin (2.5v in my case), I expect to get the square wave pulses on the output pin. Is this procedure good enough? I also felt that I-sense pin must be for protection against shorting of SMPS output power supply. Hence , I skip applying a current to this pin, but I am not sure and need advice.

What is the purpose of I-Sense current in a PWM controller IC?


texts: EAGLE CAD Connecting fills to components and leave traces bare

texts:
So I have actually have two different questions, I am making a custom board for one of my projects and I can not seem to get the result I want using eagle cad.

This is what I have in eagle

Its a small board with 3 SMD components on each side (front and back sides mirror each other) and I drew out copper pours for the busses (High amperage I plan to flow solder to make a beefy connection)

However when I upload it to Oshpark I get this

As you can see it comes up with gaps between the fill and the SMD Pads, Not sure how to fix this Ive done some research with little success.

THe other problem I am having is that I would like to have the copper pours bare but when I upload them I get this:

And I can not figure out how to take off the coating on top of the fill.

Here is a link to my BRD file: https://drive.google.com/open?id=0B6GY9aA5YJi8bU9pZUtnR3BvRHc

Thanks in advance,
Jaret


texts: Voltage divider with MOSFET for light detector with Raspberry Pi

texts:
Given the Pi’s 3.3V logic and risk of “frying it” with higher voltage applied at GPIO pin, I am using a voltage divider with MOSFET as a electronically-controlled switch to supply GPIO input. The circuit is as shown in C below.

Fig. A is the basic voltage divider with a switch. In B, I have replaced the switch with a MOSFET (n channel, P30N06LE) which is operated by Vi at gate from a sensor and feeds Vo to GPIO. (The light sensor is a photoresistor in voltage divider configuration and not shown. Sufficient to know that it switches MOSFET on and off correctly per lighting condition.) The Vo is still 5V for logic high in B, so I have inserted a diode with voltage drop of 2V in C to reduce voltage to 3V suitable for Pi GPIO. The diode I have used is a LED, which has the additional benefit of informing status (on/off).

This is the implementation I have tested on breadboard with a bench power supply. It operates correctly, so the LED comes on in the dark and Vo is near 3V in ambient light and 0V in dark or dim light.

So am I good to wire up Vo to Pi without frying it?


texts: 2.5ns analogue beamformer (8 to 1 channel)

texts:
I’m looking for a chip or system that can receive eight ultrasonic signals from 1 MHz up to 10 MHz, delay each channel with a set delay (minimum of 2,5ns and max 2,5us), combine them (sum or sum/avg) and send the combined (analogue) signal out again. This system should preferably be analogue, but if it must internally be digital the sampling rate should be sufficient to exclude under-sampling.

I would be very thankful if anyone of you knew such a system or a vendor that makes such products.


texts:
I am building a frequency generator circuit and need some advice. I am using the AD9833 DDS generator (programmed from a PIC16F876) to generate frequencies and I wish to be able to adjust the gain.

Being unable to find a suitable Programmable Gain Amplifier I was going to use a non-inverting amplifier and a digital potentiometer.
The advice I need is:

Is it better (less noisy) to pass the signal through the potential divider (in a passive fashion) inputting in to a unity gain amplifier;

OR

Should I use a digital resistor in the feedback loop of the amplifier and set the gain that way?

Also, if anyone else has any better ideas they would also be welcome, but board space is limited so complex solutions maybe hard to implement.


texts: Voltage Follower Circuit Output Changes based on Load Resistance

texts:
I am trying to simulate a circuit which can act as a voltage follower for a headlight. I simulated the circuit using CircuitLab.

I simulated two conditions:

When headlight resistance is 10 Ohm.

When headlight resistance is 100 Ohm.

Can you please explain me why I am getting different voltages in these conditions? My initial thought was that the lamp resistance should not have affected the output of the op-amp. Below is the op-amp parameters:


texts: Why more voltage after full rectification

texts:
I used 105j 400 V capacitor. Connected it  to 230 V AC. Then I measured voltage after capacitor and it was reduced to 116 V AC.
Then I checked voltage after 4 diode rectification, here measured 204 V DC.

Why the measured voltage is higher?
Is it safe or or dangerous to touch this 204 DC volt?

This is first time I'm posting in this forum. I don't know how to upload pics
Actually the capacitor I'm referring is AC voltage drop capacitor. So o for I have not connect anything after bridge rectifier

Thank you.


texts: Should I terminate the MII/RMII interfaces?

texts: For Ethernet PHY design, the MDI interface should be terminated. Then how about the MII/RMII or GMII/RGMII interfaces? I've seen some designs terminated them, and most not. There are some PHY chips even advertise they have integrated termination on chip, such as TI's DP83640.


texts: I am using this voltage divider circuit on a control board. Customer brought a board back stating the board wouldn't function after a few months in the field. After inspection, I found the 4.3kΩ resistor failed open. The resistor shows no signs of discoloration of any kind, but measures open. I've never seen a resistor just fail in this way. Has anyone else seen such a thing?


texts:
I'm currently trying to design a circuit for my car which will switch itself OFF or ON depending on +12V signal from ACC(accessory) cable.

Car is providing me a +12V battery power, +12V accessory power and ground,
i would like to make a circuit which detects +12V on ACC and then uses +12V from battery power.

Obvious solution is to use relay switch, but I'm curious are there any other options how it can be done ?

I'd be grateful for example circuits :)


texts: When would I not want to replace a PN diode with a Schottky diode

texts:
When repairing or maintaining equipment, or even during design revisions, why would I, for electrical reasons (not interested in the potential financial aspects) not want to replace a PN junction with a Schottky diode? Three reasons I can come up with:

Leakage: Schottky diodes have, in general, larger leakage
Biasing: If the PN junction is used to bias other devices (such as is sometimes done in BJT output Class AB amplifiers)
Switching applications: We might desire to use the slow reverse-recovery in RF switches.

Are there any others? In my specific case, I am replacing diodes in a older HP 6253A powersupply. The powersupply has several 3A rated PN junctions in the signal path which look very corroded, and I have a number of 6A Schottky diodes I am looking to replace them with. Is there any reason why I wouldn't want to do so?


texts: Why do AC SSRs have lower AC Voltage limits and what does this mean?

texts: I want to use something like a Crydom D2450 SSR to switch AC current supplied by a variable transformer. This device is spec'd at 24-280VAC on the output. Why is there a lower output voltage limit (24VAC)? My device seems to work as low as a couple volts out of the transformer.


texts: I need some help Identifying a component it is on the main board of an electronic speed controller

texts:
I have a speed controller that blew out due to a bad motor. I have since purchased a new controller and have taken it apart to see if I can fix it. I am no professional at all as I do this as a hobby but I do enjoy learning and I have not had any luck searching the internet for this part number so any help would be much appreciated. Thanks

The number on it is
22-16L
A3 With a 2 in a circle


texts: Drive 12V 1A with 3.3V 10mA (the cheap & easy way)

texts:
I found many disussions on the internet regarding this issue, but as an engineering noob I cannot get a proper circuit working :(

What I want to achieve: I want to control the ignition line of a car by small chip. The ignition therefore has to be connected to the 12V car battery. The chip's output pins only provide 3.3V @ ~10mA.

I thought of a 3V relay (e.g. G5V1-3), but this requires more than 10mA of power. What's the best/easiest/cheapest solution to this? Power consumption should be <0.1mA when the circuit is off. I would like to keep the car's and chip's circuits as independent as possible (that's why I thought of a relay). Toggling frequency is <10Hz.

Thank you!!


texts:
What does it mean being above resonance?
Does it mean that our frequency is more than the resonance frequency?
In an LC circuit, why is circuit more inductive when frequency is above resonance?


texts: Why doesn't PCIe and similar signaling systems use full-duplex links?

texts:
I'd like to get more PCIe bandwidth for GPU compute applications. It occurred to me that PCIe bidirectional links are really dual simplex (a pair of unidirectional links). That means if there's no data to transmit in 1 direction, 1/2 the links are idle!

So, my question is obviously, why not allow the links to be bidirectional (half-duplex)?

I can't think of any other networking physical layer that's bidirectional, except I2C and Wifi, which I doubt can reach GhZ speeds. Is high speed incompatible with bidirectionality?

Update:
I did think of a high speed bidirectional interface: a memory bus. XDR memory uses differential signaling and claims 20 Gbits/s per pin! Why does it work for memory but not for PCIe?


texts: OrCAD: Determining which trace in Secondary Sweep is which after simulating

texts:
When you run a primary and secondary sweep, there are multiple sets of traces for the same signal, where each individual trace represents a different value from the secondary sweep. In OrCAD 16.0, I want to know which secondary sweep value produced a particular trace; how do I do that?

Edit: I tried Linkyyy's suggestion and got the following info box:

So it tells me what generated that trace, but not the specific value of the secondary parameter that generated it.

Am I doing something wrong? Should I be using parametric sweeps instead of and/or in addition to secondary sweeps?


texts: FPC Connector on a Laser Distance Module

texts:
I recently purchased some RS232 laser distance modules from overseas and I'm just in the process of trying to get them going. Basically it takes 4 I/O's - Ground, + 3VDC, TX, RX.

It has an 8 way FPC 0.5mm connector on it which can be used for the TX and RX, however I want to go from that, to individual leads so I can connect them up to the USB interface for the RS232.

What adaptors are available for converting from FPC to Individual connectors, (aside from buying a FPC jumper cable and trying to pull the strands apart)?


texts: Ultrasonic sensor doesn't work inside case

texts: I have a very strange error. My ultrasonic sensor, when both speakers are sticking out of my case, doesn't work at all. It's a black case. It gives very "near" readings. But it does work when outside. Why could this be an issue?


texts: DIY Christmas Tree LED Ornament – Adding SMD Switch to power on ATTiny45 and Wiring Tag Connect to Attiny

texts:
I have taken the Open Source Christmas Tree Ornament project from Brian Schulteis and put it on GitHub under newmatik/Weihnachtsbaum (please Fork!) with a couple of modifications:

Added 20mm cell battery (CR2032) as power source so the ornament can work without being connected to permanent 5V through cables
Added a LDO Voltage Regulator (LP3985IM5-5.0/NOPB) to convert our 3V into 5V

I believe I have done that correctly. However now I want to do the following and I am stuck since this is my very fast Eagle project and I am not an Electronics Engineer:

Adding the Tag Connect TC2050-IDC-NL and wiring it correctly to J1 (2x6 connection header). I did not find a good instruction on what pin goes where and it doesn't seem like it is 1-1, 2-2, ... 6-6. I find the Tag Connect makes it much easier to connect the PCB for programming.
Enable SMD tactile switch to (1st click) switch device on all lights on (2nd click) LED blinking effect every 3 seconds (3rd click) LED cycling various effects and (4th click) turn it off again saving battery. How can I switch on the ATTiny45-20SUR and make it enable to input logic of the LP3985IM5-5.0/NOPB? Do In need a ATTiny with more IO for that?


texts: Is it ok to use digital potentiometers in parallel?

texts:
I searched but found nowhere on the web if I can use digital potentiometers like parallel resistors.

I.e. the MCP42010 has two digital resistors build in one chip.

I have the 10k version but I need max 5k. So if I would use them parallel the max would be 5k with a higher resolution.

https://www.microchip.com/wwwproducts/en/MCP42010

I guess it should work but I thought I better ask before I see the magic smoke. ;)

Can anybody confirm if it is ok to use digital potentiometers in parallel?


texts: Help to calculate heat dissipation on plastic dual in line DIP package (DIP-8 opamp)

texts:
Question is about maximum chip heat dissipation (and not about efficiency or correctness of this design).

Circuit is quite simple: put in parallel 30 Dual Opamps in 8 pin DIL package (i.e 60 opamps in parallel in unity gain configuration) to pilot 4ohm load. For each opamp there is a 5 ohm resistor (Rout) at their output to avoid they fight each other.

Vin is a sine wave of 1KHz (about 12 VACmax)
In theory 12VAC on 4ohm would be 36W @ 3A
This split by 60 opamp, means roughly 600mW @ 50mA load each opamp.

R=4ohm

No Chip=30

No OpAmp=60

RShared= 4ohm * 60 opamp = 240ohm

Rout single = 5ohm

RL = RShared + Rout = 240 + 5 = 245ohm

So I suppose each opamp will be current-like loaded by 245 ohm. (Correct?)

Then I need to calculate package dissipation for a DIL 8 pin plastic package:

Tj Max  = 150°C

OJA = 130°C/W (8-LEAD PDIP PACKAGE) from datasheet

Current max (from datasheet) for each opamp is

IS Max  = 8.7mA

Vs+ = 15V

Vs- = -15V

PSupply Max each opamp= (15 + 15 ) *8.7 = 261mW

Datasheet says (pg 10): "worst case power dissipation occurs at the maximum supply current and when the output voltage is at 1/2 of either supply voltage
(or the maximum swing if less than 1/2 supply voltage)".

For each amplifier PDMax is:

PDMax each=

= PSupply Max + (Vs+/2)^2/RL

= 261mW + 230mW = 491mW

For total chip (dual op-amp):

PDMax chip= PDMax each * 2 = 982mW

TJ Chip: Tj= TA + (PDMax * 130 °C/W) = TA + (0,982 * 130) = TA + 128°

TA Max = Tj Max - 128° = 150° - 128°= 22° (<< 70°C !!!)

As my ambient temperature is 25° or even above, any heatsink on the DIP 8 chips would not work, and will my amplifier smoke in any case??

I really need to change the Op-amp or increase the number of op-amp or give up to this project?

Is this correct?
Are all above assumptions correct?
Many thanks.

THIS IS THE LINK TO THE DATASHEET


texts:
I need to build a controllable output shutdown for the OPA 564 so I can force the amp to shut down. The solution in the datasheet uses an optocoupler but I rather use it with some pull-down resistor. My build uses dual-supply with +/- 6,2 V.
In this link you have the datasheet of OP 564: http://www.ti.com/lit/ds/symlink/opa564.pdf

Could this be a solution?


texts: Why USB-C has 4 Vbus? And how does it affect my design?

texts: I'm making my first pcb design and decided to use UCB-C to power it. I don't understand why such connector has 4 Vbus. Is it fine for me to just use one? Are there benefits to distributing power over all of them instead of one?


texts:
This question is of a purely theorethical nature.
Applying pressure to a piezoelectric material creates voltage, and the inverse is also true. I have seen this likened to a spring, and was wondering how far you could take this concept.
Imagine the following scenario: You apply a voltage to cause a mechanical oscillation, then you use glass or plastic to encase and freeze it in an excited state. (I know it's impossible, the crystal itself would melt and the material would take some time to settle, but bear with me.)
Frozen in that state, question 1, would it retain its potential mechanical energy, and 2, if you were to break the glass  would it still produce a voltage?


texts: Why do simple optical fibers usually support only half-duplex communication?

texts:
I'm a newbie to the subject, so a thorough answer would be very helpful.
I was curious as to why simple (single) optical fibers usually don't allow full-duplex communication. To my understanding, all basic optical fiber configurations support only half-duplex communication.
As I tried to find an answer to this question, I found out that there are many ways of multiplexing rx/tx in parallel on the same fiber (e.g. Wavelength-division multiplexing and Time-division multiplexing). But to my surprise, the only solution I found for a fully-parallel communication with a single wavelength is a relatively new technology from CableLabs, namely Direction-division multiplexing.
So my questions are:

Why can't simple optical communication systems transmit and receive light of a single wavelength in parallel?
Why doesn't the same problem occur when using multiple wavelengths (e.g. in Wavelength-division multiplexing)?
How does Direction-division multiplexing solve that problem?

The answers to "Are optical fibers full duplex?" don't satisfy my questions above. One answer mentions "reflections" as a problem preventing full duplex, but it is missing a more in-depth physical explanation and some credible sources.


texts: I'm trying to design and build a smps that has a 120VAC input with a 5VDC (2 Amp) output and this is what I have designed for it so far. I was thinking of having a pic18f4685 to do the pwm to drive the gate of my mosfet. According to my simulation results I need 18V ~42% Duty Cycle at 400KHz in order to have the buck converter work correctly. I'm having trouble picking out a gate driver that works with my design. Can anyone recommend a through hole ic that I can use on a breadboard to test out? Is there any ic's that do feedback also so that I can possibly eliminate using a pic chip? I can't buy a complete buck converter ic for my project and it has to be custom. Just trying to build the easier smps possible without buying an ic that does everything! I appreciate all the input. If you have some schematic of a simple buck converter laying around that isn't just an ic please share it.


texts:
I am implementing a USB to UART conversion board with a FT232RQ. What confuses me is the fact that the USB_D+ and USB_D- pins of the package are sequenced in precisely the opposite order as they are on any USB connector.
What options do I have to properly route the USB traces? I have come up with the following but I am not really satisfied with any. On the other hand I am at most a beginner so your hints might help clarifying the issue.

use a through-hole USB connector and place the FT232RQ on the opposite side to the connector such that the traces go straight
use a SMD connector and place the FT232RQ on the opposite side, but route the traces through vias
place the components on the same side and do some crazy trace gymnastics (having to match their length).

Additionally, being a quad-flat package, there is no possibility of routing the USB traces "under" the package.
Is this even a "real" problem? The confusion might be fully due to my lack of experience in the field.
Thanks you!


texts: Does data rate depends on Frequency not on BW?

texts: If we have two RF signals of 900Mhz and 1800Mhz both of equal Bandwidth 20Mhz which one has higher data rate?


texts:
Need help to identify resistor found in car ECU. Colour: Solid sky blue. Markings are: 100J and .36.  Need explanation of what markings refer to.
 See example pic:

(Source)


texts: Why does a 240 volt outlet save money in electrical cost than a 120 volt outlet?

texts:
I live in the US and we have many outlets that run at 120 Volts.  I heard that for devices that support the 240 volt standard may not cost as much in electricity prices.

Can someone explain how by simply binding two 110 circuits together that is creates a money or electrical power savings when operating at 240 volts?

I vaguely know of AC "phases".  When a 240 circuit is created out of two 110 circuits, what happens w.r.t. the phases in the circuits?


texts: Isolated DC DC converter operating principle

texts:
I'm doing a course project on electrical engineering subject. I have to use this specific DC DC converter ISL2412 XP Power DC DC converter. But before I can use it, I have to explain how does it work.

I can't find anything about it's operating principle. The only thing I found out is that it isolated type. So this type of DC DC converters has galvanic isolation, is that the main part of it that do voltage transform?

So the question is, what is the isolated DC DC converter operating principle?


texts:
We have the query regarding Stack up, 50-ohm Impedance traces and its Reference Layers.

Recently We want to fabricate 6 layers 50-ohm impedance controlled board. but in this PCB We have to Routed 50 Ohm Impedance traces on Layers L1, L3, L4, and L6.

And we are providing L2 - GND Layer and L5 - POWER as a reference Layer for all above Layers.

So we want to know that if 50 Ohm impedance traces are on L6 Layer then its reference layer is L5 which is POWER Layer.

Will it affect our 50 Ohm impedance traces or it will take reference from L2 (GND) layer?

Or we have to change Layer L5 to GND to provide reference Layer to L6?

Let us know if you required more information regarding our query.


texts:
I'm not asking about the safety of which solder, I'm asking about which type of solder would be best for my purposes

I'm a novice electronic hobbyist and I just want to know what composition of solder should I get that will do the job the best, for the best price. There are many different compositions of solder wire and I really don't know which would be best for some simple circuit soldering.

If someone could breakdown what solder they would get for hobbyist purpose, could you let me know. In addition could you breakdown what metal composition of leaded solder, lead free, and tin-lead, would be suffice for my purposes.


texts:
I need to specify the construction of a 4-layer PCB with transmission lines on the outer layers and planes on the inner layers. I need to control impedance and propagation speed. The target prepreg thickness is around 0.2mm (7-8mil). I can achieve that with a single ply of 7628 or with two plies of 2113 or 1080.

Most PCB stack-up I have seen use two plies for prepreg layers, even if the same thickness could be accomplished with a single, thicker ply. Why is that? What are the advantages and disadvantages of one versus two plies?


texts: Constant static thrust from a brushed motor powered by minimal weight rechargeable battery

texts:
I am trying to design a circuit for a device that will only run for around 20s at a time.   For that 20s, however, I need to power two brushed motors (with connected propellers) that together pull around 5a @ 9v under load.
 For my application I need a near constant static thrust for those 20s.   I think the easiest way to do this would be to hold the voltage across the motors constant.   I am looking to minimize weight, however, and need a power source that is rechargeable, and only has a little bit more than the energy required for this application.

What circuit/power source should I choose?

One option might be to use a voltage regulator to keep a constant voltage for those 20s and choose the smallest possible battery that would not drop below the regulator's minimum input voltage for the duration of the 20s (with some headroom).

To eliminate the voltage regulator is there any power source that is both rechargeable and can output near constant voltage for the majority of its life cycles?   I'm guessing no.


texts:
I have one logic 3v3-input (5v non tolerant) on my microcontroler and I want to interface 4 5v-inputs.

So my idea was to connect a multiplexer supplied in 3v3 but I have seen in datasheet (for exemple 74HC4052) that  Vi (input voltage) must be GND and Vcc and Vcc can up to 10V.

What's happen if Vi=5V and Vcc=3v3? It burns or the Vo=3v3?

Should I use a digital multiplexer (5v tolerant)?

What is the best solution with only one component?


texts: what is the collector gain of a transistor?

texts: I was wondering what exactly collector gain is for npn transistors, or more specifically if there is some sort of equation for getting it, and if its value changes as you change the input voltage/current. I have searched google for this but I am quite new to transistors and am having a hard time understanding the stuff and understanding what they are talking about.


texts: Maximum input capacitance of IO-Link-Device on C/Q

texts:
I have a bit of trouble understanding the IO-Link-specification concerning the input capacitance of the C/Q-pin.

The specification says in table 7 (line 754):

  CQD Input capacitance min: 0  max: 1,0 nF, Effective capacitance
  between C/Q and L+ or L- of Device in receive state

Do I have to interpret it this way:

simulate this circuit – Schematic created using CircuitLab

Or this way:

simulate this circuit

This might be a rather stupid question but or for me is ambiguous in this case (like here).


texts:
Maybe this is not the right place to ask this, it is so, please tell and I will delete this question.

I want to learn how information is transmitted using radio and TV. I want to learn that because I want to know if it is possible to use another electromagnetic wave, like visible light, to send information.

What do you recommend me to start learning how information is transmitted using radio or TV?


texts:
I'm trying to implement multiplication in a cpu I designed. I'm trying to achieve this with some conditions. I only two general purpose registers Rx and Ry and these instructions:

Add Rx, Ry             [Add take Rx and Ry to ALU and returns result to Rx]
LD Rx, address         [Load takes the data in RAM from address and loads to Rx]
STR Rx, address        [Store takes data from Rx and stores to address in RAM]
BZ Rx, Ry, Address     [Branch compares the data in two registers. Jumps if equal]
Jump Address           [Jumps to address]

If I only have 2 registers and RAM, is there a way to implement multiplication? I know the general way to implement it is by using shifts but I don't have the implemented and would prefer not to. I was thinking of looping an addition call but I can't seem to get that work since I only have 2 registers.

EDIT:
You can select which register by addressing them either 0 or 1.
Also, my RAM is only 16 bytes large and the bus is only 8 bits within the CPU.

Add Rx, Ry             [Rx <= Rx + Ry]
LD Rx, address         [Rx <= RAM(address)]
STR Rx, address        [RAM(address) <= Rx]
BZ Rx, Ry, Address     [Branch to Address If Rx == Ry ]
Jump Address           [Jumps to address]

The address is a 4-bit constant stored in the instruction. Rx or Ry are 1 bit. OPCODE is 4 bit with the exception of LD and STR where 4th bit of OPCode refers to register selection.


texts: hilti PX 10 TRANSPOINTER working principle

texts:
Sorry to ask this here. But I really got wondered what is this product's working principle. Anybody share what would be the core  idea behind this product PX 10 TRANSPOINTER from hilti.

Click here to find the product official page


texts: Upgrading a device female micro-USB connector to USB-C

texts:
I have a battery manager PCB, which has a microUSB female connector for power-input (5V from smartphone charger for instance).
The power input is fed to a PMU which charges a lipo battery and power a system (an old toy-train that was running on LR14).
It does not need data transmission. Only power to charge the battery.
I want to replace the power input connector by a female USB-C. Should I just connect the microUSB VBUS to the USBC VBUS and GND to GND? Or should I also add pull up/down resistors?
I got that female USB-C breakout board from aliexpress (the blue one from the pictures) : https://fr.aliexpress.com/item/1005001337982060.html?spm=a2g0s.9042311.0.0.87526c37416MK1
But it has only 1 footprint for a resistor.
I was expecting 2 resistors footprint, one for A5 and one for B5, on which I thought I needed to put 5.2k pull down resistors.
Also this connector has only 7 pins on each side instead of 12.
From the PCB pictures it looks like the R1 resistor is connected to both A5 and B5 on one side, and to GND to the other side. Is it OK to solder only one pull down resistor like this?
It feels dirty and makes me think about the issues the raspberry pi 4 had where they applied only one resistor. Though I could not find the exact schematic error that RaspberryPi did.


texts:
I have an ARM Cortex M3 STMF32F103VE http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00191185.pdf, and I'm using an LCD with ILI9320 controller http://www.densitron.com/uploadedFiles/Displays/Support/ILI9320AN_V0.92.pdf

I'm using controlling the LCD using the FSMC, and I'm trying to write for example 240*100*16bit bytes and it takes about 0.1Seconds for that operation and the clock is 72Mhz.

for(i=0;i<240*100;i++)
    {
      *(__IO uint16_t *) (Bank1_LCD_D) = frameBuffer[i];
    }

The code for initializing the FSMC is copied and paste from the STMF32 application note for using an LCD TFT with FSMC:

#define Bank1_LCD_D    ((uint32_t)0x60020000)    //disp Data ADDR
#define Bank1_LCD_C    ((uint32_t)0x60000000)    //disp Reg ADDR

/**
  * @brief  Configures the FSMC and GPIOs to interface with the SRAM memory.
  *         This function must be called before any write/read operation
  *         on the SRAM.
  * @param  None
  * @retval : None
  */
void FSMC_LCD_Init(void)
{
  FSMC_NORSRAMInitTypeDef  FSMC_NORSRAMInitStructure;
  FSMC_NORSRAMTimingInitTypeDef  p;
  //GPIO_InitTypeDef GPIO_InitStructure;

  p.FSMC_AddressSetupTime = 0x02;
  p.FSMC_AddressHoldTime = 0x00;
  p.FSMC_DataSetupTime = 0x05;
  p.FSMC_BusTurnAroundDuration = 0x00;
  p.FSMC_CLKDivision = 0x00;
  p.FSMC_DataLatency = 0x00;
  p.FSMC_AccessMode = FSMC_AccessMode_B;

  FSMC_NORSRAMInitStructure.FSMC_Bank = FSMC_Bank1_NORSRAM1;
  FSMC_NORSRAMInitStructure.FSMC_DataAddressMux = FSMC_DataAddressMux_Disable;
  FSMC_NORSRAMInitStructure.FSMC_MemoryType = FSMC_MemoryType_NOR;
  FSMC_NORSRAMInitStructure.FSMC_MemoryDataWidth = FSMC_MemoryDataWidth_16b;
  FSMC_NORSRAMInitStructure.FSMC_BurstAccessMode = FSMC_BurstAccessMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignalPolarity = FSMC_WaitSignalPolarity_Low;
  FSMC_NORSRAMInitStructure.FSMC_WrapMode = FSMC_WrapMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignalActive = FSMC_WaitSignalActive_BeforeWaitState;
  FSMC_NORSRAMInitStructure.FSMC_WriteOperation = FSMC_WriteOperation_Enable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignal = FSMC_WaitSignal_Disable;
  FSMC_NORSRAMInitStructure.FSMC_ExtendedMode = FSMC_ExtendedMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WriteBurst = FSMC_WriteBurst_Disable;
  FSMC_NORSRAMInitStructure.FSMC_ReadWriteTimingStruct = &p;
  FSMC_NORSRAMInitStructure.FSMC_WriteTimingStruct = &p;

  FSMC_NORSRAMInit(&FSMC_NORSRAMInitStructure);

  /* Enable FSMC Bank1_SRAM Bank */
  FSMC_NORSRAMCmd(FSMC_Bank1_NORSRAM1, ENABLE);
}

and in main init code:

just a call to SystemInit(); and RCC_AHBPeriphClockCmd(RCC_AHBPeriph_FSMC, ENABLE);


texts: Which logic gate operation does the following circuit perform?

texts:
It is given that 1 is for voltage greater than or equal to 5 V, while 0 is for voltage less or equal to 0 V. (A and B are the inputs.)

The answer is given as AND gate.

The trouble I am having is: given the way circuit is set up, \$V_{CC}=6V=V_{out}\$ (since these points are only connected by conducting wires, assumed 0 resistance.) Then, is the question correct? A solution I found on another site states "When A and B are both 1, the current flows through R and \$V_{out}\$ is 1."

[The question is from JEE Mains Online 2014 exam.]


texts: What does this MOSFET do in this voltage regulation circuit?

texts: In the below schematic, V_USB is connected to the +5V of a USB jack, that the user can plug and unplug. There is also a backup LiPo Battery, whose positive terminal is represented by V_BATT. From my point of view, the MOSFET's function here should be to disconnect the battery from the voltage regulator's input when USB is connected. However, it seems to me that when V_USB is +5V, the MOSFET will close the connection, and V_USB will be connected to V_BATT. Shouldn't the MOSFET be closed when V_USB is low, and open when V_USB is high, the opposite of what it is now?


texts: SAR ADC driver circuit: charge bucket and OpAmp GBW

texts:
I need a theoretical clarification about how to design a driver circuit for a SAR ADC.

simulate this circuit – Schematic created using CircuitLab
I found an interesting video series (https://training.ti.com/ti-precision-labs-adcs-math-behind-r-c-component-selection) and I read some documentation from Texas Instruments, but I can't understand in detail the theory behind this circuit.
The basic idea is that the ADC S&H circuit can be modeled as a RC with a series switch, that is closed for the acquisition time "tacq". This system can generate acquisition error when the acquisition time is too fast and the hold capacitor Ch doesn't reach the input voltage level (and the voltage difference is greater than 0.5LSB).
Therefore, an external capacitor "Cfilt" known as "charge bucket" is added; this capacitor should be able to "inject" its charge into Ch when SW is closed, even if the driving opamp is not able to supply enough current and/or a large parasitic resistance/inductance is present due to physical connection (e.g. PCB trace). Therefore, thanks to charge conservation principle, a simple analysis can be made assuming that Ch is charged only by Cfilt.
From this basic idea, I would like to go one step further.
In TI's documentation and video, Rfilt is added and OA is chosen to have a sufficient GBW. Therefore, I would like to understand:

why Rfilt is added; is that needed only to guarantee op-amp stability?
how and why OA GBW can affect circuit operation (maybe the equivalent closed-loop output impedance is greater at higher frequencies?)

Moreover, I guess that a tradeoff between Cfilt value and OA GBW value can be found and different choices can be made to mainain a cheaper opamp with a larger Cfilt (therefore large Rfilt to guarantee stability => lower cutoff frequency of such a Rfilt-Cfilt LP filter) or vice-versa.
I would like to get an idea or the title of a reference book to be read. My goal is to build up a good knowledge about this topic to fully understand what are design reasons and variables.


texts: How a constant current of 23 mA flows from the capacitor when the transisitor turned on?

texts:
simulate this circuit – Schematic created using CircuitLab

The following is a circuit I got from a research paper and I am trying to analyze it. The inverter is a high speed inverting buffer whose output is always one. The circuit starts functioning when the inverter sends an output of zero. I will quote the sentences in the paper about the idle conditions (When inverter output is one)

  "The output of inverter biases Q1 Such that its emitter Voltage is higher than the base voltage of Q3, thus cutting off the collector current of Q3.
  Capacitor C6 will have been charged to 5 volts through R17
  with a time constant of about 5 us"

When the inverter ouput is zero,

  "The inverter
  generates a fast falling edge and quickly turns off Q1 thus
  turning on Q2.The collector
  of Q2 draws a constant 23 ma from C1, thus discharging it
  at the uniform rate of 0.1 volts per nanoSecond"

My doubts :

1) How turning off Q1 can turn on Q2?

2) When Q2 is turned on, how the collector become constant taking 23 mA from C1?


texts:
I'm new to making any electrical desings that don't have a manual.

I have six 12 V 20 Ah Lead-Acid batteries connected in series.

Can a 12 V 14 Ah or/and a 12 V 6.5 Ah battery(ies) be connected in any manner in which it won't harm the life span of the "original" six batteries?


texts: RC anti-aliasing filter for a pulse train

texts:
Many data-acquisiton boards are recommended to use anti-aliasing filters between the analog inputs and the ADC.
Here what I understand from anti-aliasing:
If one has a DC like signal and the freq. of interests of the signal is not more than 10Hz one can use an RC low pass filter with a 20Hz cutoff freq.

But what if the signal is a pulse?
I want to make an RC aliasing filter for pulse frequencies changing between minimum 3Hz up to 500Hz.
My sampling freq is 4kHz.
In this case, one might use an RC filter with a cutoff freq of 1kHz but this could effect the rising and falling edge shapes significantly. I still want the pulse shape as sharp good as possible.

Is there a rule of thumb for an RC antialasing filter if the input is a pulse in daq systems?


texts: Maximum bit rate of a noise less channel

texts:
I am not able to find any source giving  reason as to why the maximum bit rate in a noise less channel is twice bandwidth multiplied by log L base 2 where L is number of symbols used.

What I came closest to is bit rate is twice bandwidth as a consequence of ISI and use of Nyquist pulse. But what about logL part.

Please help me out by giving a source to derivation proof or an intuitive reasoning too would do


texts: Driving a high-impedance load from a BJT base

texts:
Are there any caveats with tapping off the base of a BJT to drive a high-impedance load, such as a logic gate or op-amp? In the schematic below, I have an open-collector output from U1 sinking base current from transistor Q1 to operate a load. I would like to connect some downstream logic to the output of U1 for use elsewhere in the circuit.

The only issue I can see with this approach is ensuring that the saturation voltage of the open-collector output is low enough to register "logic low" with the downstream logic. As long as the base current of Q1 is relatively low, and U1 isn't sinking much current, I think this is attainable. (The actual thresholds will depend on the components used, of course.)

Is this practice okay, or would I be better off buffering the output to Q1 so all of the loads on U1 are high impedance? Or, is there some other design practice that's more appropriate here?


texts: Low-frequency response of a CS amplifier

texts:
I would like to ask for the sentece below in the the red box  if fp2=400Hz, fp2=100Hz and fp1=60Hz then I can assume that fL=fp2=400Hz? And the other case  if fp2=300Hz, fp2=100Hz and fp1=60Hz then fL=fp1+fp2+fp3=460Hz?

I ask this because I saw a problem where fp2=500Hz, fp2=100Hz and fp1=60Hz and  calculate that fL=fp1+fp2+fp3=660Hz.This is correct?I think from the theory below should give us fL=500Hz.


texts: Magnetometer moving along a line with different measurement?

texts: I am testing on a magnetometer and found that moving the magnetometer along a straight line within the range around 1m, and the measurement varies. From what I understand, moving magnetometer along a line won't change its orientation and the range within 1m guarantees that the magnetometer won't suffer much from soft-iron distortion(test in many environments), so I am quite confused about what's happening here...


texts: PCB practices: Grounding, and interaction b/w switching and control loops

texts:
This is kind of 3rd in a series, following the posts Advice on ground plane in my first PCB and then Separating ground planes in PCBs. In terms of material, though, it can be considered a post on its own. So to summarize the PCB below (prepared using ExpressPCB) is for a flyback converter implementation using the LT3748 boundary mode flyback controller IC. The circuit is taken from the LT3748 datasheet itself (see very last page). This is for a class project.

I have attempted an improved PCB based on advice in previous posts. I have two versions, shown below.

My questions are:

The switching loop goes around the controller (since the tracks go under the IC - but in the same layer of the IC). Is this very bad for noise? BTW, would you consider the switching loop to be Vin-xformer-Q1-R8, or C1-xformer-Q1-R8?
For top version, all tracks are on top layer only, but many of them go under the IC (on the same top layer). Is that bad practice? I cannot guarantee the IC won't heat up since the datasheet quotes performance at temperatures up to 150 C.
I have only one ground on the primary side. I'm not sure how in my situation to keep a separate ground for the small-signal and high-current loops. I can do but this will put a few breaks in my ground plane...

Finally, as a note, another difficult constraint I was trying to meet is that the controller datasheet says the sense resistor (R8) ground should be close to controller IC, but at the same time to keep the switching loop tight R8 needs to be close to the capacitor.

Keeping all of this in mind, which design would you think would perform better - or is it neither :) Note that teh second design has a few tracks on the bottom layer (green).


texts: Why would I need costly software libraries for a layer 2/3 ethernet switch?

texts:
I am a novice electronics engineer and it is my first time implementing Ethernet links in my designs.
We recently bought a Connect Tech XDG007 GbE Switch, which will serve as a simple L2 Ethernet switch for several sub-systems to communicate together.
This COTS PCB has magnetics, power supplies, a memory IC and a Vitesse VSC7428X which handles all the switching (it has integrated PHYs). I thought "I can use this for the prototype, and then use the VSC chip on a board of my own for the real product".
However, when discussing this with the rep that sold me the XDG007, he informed of several software libraries that have to be purchased from the manufacturer (Microchip here) in order to get it working (he mentioned tens of thousands of $). He was unable to get into the technical details of exactly how and why, which is why I'm here.
My first impression, reading through Connect Tech's documentation, and skimming through some of Vitesse's application notes (AN1115 & AN1104), is that the ICLI (RS-232) and Web Interfaces (Ethernet) are available as soon as you boot up the device. Once each port is configured with the correct speed/protocol, it can perform the bare minimum switching function.
Here is the Software support matrix between software packages and Ethernet switch ICs by Microchip:

I went on and read each of the software packages' pages that are "compatible" with the VSC7428, and still have no clue as to why I would want to pay for a SDK to perform simple ICLI commands that are perfectly described in available datasheets.
So that leaves me with: these software packages are designed to be used on embedded processors that have to interface with the VSC chips, but somehow can't use the ICLI link "as is"? Here I am making the assumption that these software packages are very expensive, and heavy, but that may not be the case. If they are just convenience drivers used to speed-up designs then I can see the point.
Did the rep tell me all this just so I would consider buying him more products instead of making my own switch (we have several mechanical constraints that make the use of a COTS board a PITA)?
I put this in EE because I considered it to be too low-level design considerations to be appropriate in SO.


texts: capacitor or 2nd battery for invertor situation (automotive)

texts:
Background

I have a power inverter in my car that I installed about 4 months ago.  I bolted the ground on it to the ground terminal connector of my car battery and the + to the positive side of it.  Fast forward to present, my ground on my car is corroded significantly  and the nut and bolt on it have corroded so badly that the nut has puffed and the terminal is orange (both were silver instead of that poopy color).  Ill add a picture of it.

One part of the problem was that these terminal connectors are junk, ground one never really clamped on the battery that well (decent but could be bumped off with your hand no matter how tight you tightened it) and I have replaced that old terminal with one like this (  https://www.electricalhub.com/generic--battery-terminal-top-post-1  ) as my car would no longer start with the old one and was just giving me way too many problems.

Capacitor / Battery situation question

With that said I am trying to figure out how best to handle the inverter now that I have replaced the battery terminal.  One problem I had with it outside of the corrosion thing is that when I start my car, the inverter would freak out and start beaping at me until I turned the inverter off and then back on after having started my car.  I am assuming that it either doesn't like the electrical noise that occurs from starting my car, or the voltage drop from staring my car would drop the inverter low enough that it would not work until it was turned off and then back on as some kind of annoying (to me) safety feature...  The inverter works fine outside of when i start the car however.

I was thinking about either getting a small motorcycle battery that would act as a buffer between the car battery and the inverter to reduce noise/ voltage drop  or getting a large capacitor instead.  Both I would put closer the the inverter as I have about a 7-8 foot run from the battery to the inverter.

[Frame]--[Battery]--------[Inverter]

[Frame]--[Battery]------[2nd Bat or Capacitor]--[Inverter]

1 "-" is equal to 1 foot of wire

if a capacitor is the better way to go, can you please link me to one?  the best I can find is ones made for 440V and I feel like that would be overkill.  I don't really know how to differentiate capacitors so a dummed down explanation would be awesome since I am not sure how to make google give me an explanation i could follow since the ones I was looking at had stuff like 40-5 and 60-7.5 in the description which threw me for a loop


texts: Advice on Arduino project for smart light bulb planning

texts:
I'm starting a new project (for personal use), I want to build a circuit that will enable me to control a lightbulb through my phone. I want to use it as an additional lighting at my living room.
after researching online, I have a general idea about how I want to build the system. The block diagram is depicted bellow:

Links to the parts I'm planning to use:

Arduino Uno + wifi module + adequate power supply
relay
light bulb socket - I'm still not sure it'll be the exact socket (since I still haven't chose the light bulb itself, but the only thing that will change is the type of the light bulb, the cable with the plug will look the same)

I have a few things I'm not sure about:

Can I connect the relay directly to the wifi board? In all the tutorials I've watched, such as this one, that was exactly what they did, but I read in some places that it's dangerous. If it is, how should I connect the relay and the board?
The Wifi board I'm planning to use is Arduino Uno with wifi module, I chose this one since I already have it. Are there any better alternatives? I'd like to hear your opinion about which wifi board to choose for this project.
I would be happy to hear your opinion about the whole planning, please note that I'm a beginner, so I'm looking for something relatively simple, but not too simple (such as buying a wifi controled light bulb from amazon). any opinion and advice will be highly appreciated!

Thank you.


texts: How to deal with a complex circuit of resistors and capacitors?

texts:
simulate this circuit – Schematic created using CircuitLab

Assuming i have the circuit from above and i need to find the current through every resistor and capacitor.
the switch opens at t=0.
I can see the symmetry that on the left flank all the resistors are 2 ohm resistors while in the right flank they are all 1 ohm, but i still can't figure how to find ALL the current's that runs through each resistor and capacitor.
Any tips please?


texts:
I'm designing a wireless charger project for our UV light cure system and don't want to buy a wireless module because they are not professional actually (using very simple components without any protection on the TX side) instead, I want to use full-bridge MOSFET arrangement on TX side and Litz wire in the coils.
So my question is because of the lack of thin ferrite plate in our market, I want to use a 2mm metal plate instead of ferrite in the back of the coils! what is your suggestion? Is it OK?


texts: Is there such thing as a PWM Transistor?

texts:
I have a 7-channel RC receiver that outputs PWM at 5V. One of the channels is controlled by a simple switch (on/off) on the transmitter.

I'd like to use this switch to control a 24V device. The problem is that this device only accepts binary input (no PWM). Even when the PWM is considered "off", there is still that little spike on the oscilloscope, and "on" just has a wider spike (which, as far as I know, is how PWM is designed).

Is there such thing as a transistor or transistor-like device that can interpret a PWM signal and open/close a "collector" and "emitter" based on the width of the pulse in a PWM signal?

Disclaimer: I am not a professional electrical engineer. There may be a simple answer in front of me that I'm not aware of.

If I'm not providing enough information, let me know.


texts: What cause extreme heat when electricity connect to it?

texts:
I want to know is there a item/chemical etc, that cause extreme heat if it comes into contact with even a small bit of electric currents?

I ask cause I am doing a school project and I need something to generation heat using electricity as it would be very covenant. Thanks

Update: Sorry this question was unclear. I have done a bit of research since posting and hopeful I can make this more clear. I am trying to find away to amplify heat created by joules. ohmic heating is kind of what I'm talking about. How can I make a large volume of heat using that law? Do I need a large amount of electricity flowing or could I use a small bit of electricity and some how amplify it.


texts:
I have an msp430 synth project and can't decide on the output:

I get an 8 bit ~45kHz PWM output out of the chip which I'd like to use as an audio signal, but I am unsure whether

I can just stick an impulse amplifier on it and let it in a speaker through a decoupling capacitor
I should filter off the PWM frequency

So the question is - should I filter off the ~45kHz component of the signal before I let it into any audio output device (amplified speakers, headphones etc.).

I do know for a fact that it'll work either way, I'm just concerned about damaging any additional amplifiers following in the signal path and harming the speakers themselves. So I'd appreciate tips from someone with experience with this.


texts: Timer 1 can't increment on external T1OSI source for PIC16f627A

texts:
New to PIC programming

Trying to Simulate a PIC16F627A TIMER 1 using MPLAB X IDE
where RB7/T1OSI increments, and it toggles RB4 through TMR1 ISR.

#include <stdio.h>

#include <xc.h

#pragma config WDTE = 0;

//timer1
//period 1 ms or every 100 T1CKI
//external from T1CKI rising edge (1 sec Period) T1OSCEN = 0; //
//PIN RB4

void interrupt Pulse_ISR (void)
{
    PORTBbits.RB4 = !PORTBbits.RB4;
    PIR1bits.TMR1IF = 0;
    TMR1L = 0x96;
    TMR1H = 0xFF;
}

void Init (void)
{
    //Global Interrupt
    //Peripheral Interrupt
   //TMR1IE
   //1:8 prescalar
   //t = 1us*8*N    N = 100
   //TMR1 = (2^16+1) - 100 = 65436 FF96

   TRISB4 = 0;//RB4 is output
   TRISB6 = 1;//RB6 and RB7 are input
   TRISB7 = 1;

  INTCONbits.GIE = 1;
  INTCONbits.PEIE = 1;
  PIE1bits.TMR1IE = 1;

  T1CONbits.T1CKPS = 0b11;//1:8
  T1CONbits.T1OSCEN = 1;//TMR1 increments on T1OSI RB7
  T1CONbits.TMR1CS = 1;

  TMR1L = 0x96;
  TMR1H = 0xFF;

  PORTBbits.RB4 = 1;

  T1CONbits.TMR1ON = 1;
}

void main (void)
{
    Init ();

    //I will simulate a 1 ms pulse 50% Duty Cycle at T1CKI/RB6

    while(1);
}

I created a stimuli where I created a pulse on pin RB7 with period of 500us

and I watch the result throught IO pins

I build the project and Debug it, watch RB4 IO Pins and it never toggles.

Can someone tell me why? Thank you.

MPLAB X IDE v3.55
PIC16F627A
Debugging Tool: Simulator


texts: Is 23.8°C/W junction-to-ambient thermal resistance for a TO-220 in this datasheet with or without a heatsink?

texts:
I've been reading datasheets all night trying to figure out which LDO linear regular would give me the most current at 3.3V with no heatsink from a 2S LiFePO4 battery (assuming a max voltage range of 5V-8.4V) without overheating.  The old LM1117 appears to be the best thing out there for use without a heatsink, unless I'm reading the datasheet wrong.  Am I?

Junction-to-ambient thermal resistance appears to be the relevant specification.  Some datasheets specify that they're giving this data without a heatsink (e.g. REG1117, pg. 5).  Some datasheets specify that the data is for specific areas and weights of PCB copper that the regulator is soldered to as a heatsink (e.g. TPS7A45XX, pg. 25).

For the LM1117, the value 23.8°C/W is specified for the TO-220 packages in section 6.4 on pg. 4.  There are no notes in this section specifying that heat sinking is required to achieve this value.  There are notes to that effect for other thermal characteristics (e.g. sections 6.1 and 6.3), and there are notes to that effect for other packages (e.g. TO-252 and WSON), suggesting that this number for the TO-220 package might be without a heatsink.

However... given that it's less than half of the value for similar regulators where the datasheet is unambiguous that the data is for the no-heatsink case, I'm suspicious.  Is this really the miraculous regulator I'm looking for (minus the whole tantalum capacitor requirement), one that'll give me twice as much current before overheating as anything else, or am I misreading the datasheet and/or missing something obvious?

All the regulators I've been looking at, for comparison:

LM1117: 23.8°C/W
TLV1117: 30°C/W (with the same ambiguity about heat sinking)
LT1965: 3°C/W (for junction to case, case to ambient unspecified)
LT1963A: 4°C/W (for junction to case, case to ambient unspecified)
MIC5239: 50°C/W (also ambiguous about heat sinking)
LD1117: 50°C/W
LD1117A: 50°C/W
REG1117: 65°C/W
REG104: 65°C/W
AZ1117C: 100°C/W
AZ1117I: 100°C/W
TS1117B:105°C/W
LDL1117: 120°C/W
IFX1117: 164°C/W

And a bunch which only specify thermal resistance with heatsinking, mostly soldered to PCB: BDXXC0AXXXX, NCP59150, NCP59300, TPS7A45xx, LT1117, NCP1117, NCP1117LP, SPX1117, ZLDO1117.

Edit: I picked an assortment of TO-220 datasheets from Mouser and looked at junction-to-ambient values.  Most manufacturers were pretty much always in the range 50-65°C/W.  Texas Instruments was mostly in the range 20-30°C/W.  I'm thinking that either TI has figured out a better way to make TO-220 packages that no-one else has, or they're measuring things differently.


texts: Software only USB implementation for ARM-M0/M0+?

texts:
Since I'm worried about the future of AVR, I've been looking into software USB for ARM cortex-M0/M0+ that is similar to V-USB.  All I've found is a port of LUFA, which is for MCUs with internal USB hardware.

Now I know there are Cortex-M0/M0+ controllers that do have USB hardware, although I'm looking at using the smallest lowest pin-count I possibly can which usually don't have USB hardware.  I know some of these tiny controllers will have USB hardware but they are typically in a WLCSP package which have small spacing between the pads which I cannot work with.  This is why I'm looking for a software implementation.

Is there a software only implementation of USB for ARM-M0/M0+?

note: by software, I mean firmware but it seems code-only implementations of hardware peripherals are usually referred to by software.

note 2: Please don't suggest any specific products.  The question isn't about an inability to find small controllers with USB, its about the lack of a software implementation of USB for ARM much like V-USB.


texts: How do I calculate the length of a transmission line?

texts:
A quick translation:

Generator has \$Z_g = 50\Omega\$ and 12 V. The line is loaded with an unknown RL. We observe we have a maximum of 8 V at 250 MHz and a minimum at 500 MHz.

Solution: Asks for the dielectrical permitivity and the \$Z_o\$ of the line

$$Z_o = \sqrt{L/C} = 50\Omega$$

and for the dielectrical permitivity of the dielectric it is

$$Z_o = \sqrt{\frac{\epsilon_o \epsilon_r}{\mu_o \mu_r}}$$

$$Z_o = 120\pi \cdot \sqrt{1/3}$$

from there we get the dielectrical permitivity.
This asks for the line length which is my initial question. Is wavelength same as the line length or am I wrong?

$$\lambda = \frac{v}{f} = 0.159 m$$

Thanks and sorry for my lack of English in Electrical Engineering subject.


texts:
Please take a moment to checkout at the LM386 circuit below. The circuit comes directly from the LM386 specifications document:

My question revolves around the output branch consisting of the 0.05 microfarad capacitor and the 10 ohms resistor.

At first I thought that this branch acted as some kind of RC filter but then I realized that on all RC filters (as far as I know) filtering is achieved by taping into the node between the capacitor and the resistor (which is not the case on this branch).

So what is this branch supposed to do? Is it for filtering? Also, what effect does the branch consisting of the 250 microfarad and the speaker has on the output signal? It looks like at the end both branches will combine in parallel and I am having trouble understanding how all these component work together.

Thanks.


texts: How to chose via diameter and drill size based on trace width

texts:
I am designing a two layer board, the problem is I do not know how to select via diameter and drill size, as well as outer and inner diameters.

In my circuit I use 056, 012 and 006 mil traces:

I have asked the manufacturer, they said they can make vias as  small as 1 mil.

So my question is what should I choose for Outer, Inner diameter and drill size? For example, is it OK to use 10 mil drill for 6 mill trace? and what should it be for 56 and 12 mil tracks?

Also what is the green cylinder is going to look like when I get the board manufactured?

I am really short on money I can not afford to make mistakes.