texts: Is this linear amplifier topology regarded as Class B amplifier?

texts:
We learnt in the textbook that a class B amplifier takes the following configuration (NMOS on top and PMOS on the bottom, circuit 1):

Circuit 1
However, I have also seen some linear amplifiers take the following form (PMOS on top and NMOS at the bottom, circuit 2)

Circuit 2
In circuit 2, both transistors are in common source stage and I found that circuit 2 would have the following problems:

When Vin is high, PMOS is off and NMOS is on. As Vout and Vin has 180-degree phase shift, Vout is low. It is likely that Vout < Vin. That is the drain of the NMOS is lower than the gate of the NMOS, driving the NMOS into the triode region.
Similarly, when Vin is low, PMOS is on and NMOS is off. As Vout and Vin has 180-degree phase shift, Vout is high. It is likely that Vout > Vin. That is the drain of the PMOS is higher than the gate of the PMOS, driving the PMOS into the triode region.
That means both transistors are either turned off or operate in the triode region.

So my questions are:

Is circuit 2 regarded as Class B amplifier? If not, what topology is it?
What is the operation is circuit 2?
Would the potential problems described above happen? How these problems are solved?

Thanks.


texts: If wind rotates my fan, will it cause electrical problems?

texts:
I'm planning on building a DIY dryer booster, using this cheapo 220V inline fan:

I plan to connect it to a temperature switch and a fuse, and connect it to the exhaust of my dryer. (I'm doing this because my dryer exhaust is around 6 meters long and the dryer is having a hard time pushing air that far.)

My question: Say that the air pressure from the dryer causes the blades of the fain to spin, before the fan has been turned on by the temperature switch. Will this cause the fan to generate electricity and damage itself or anything else?


texts: Output impedance of JFET source follower with constant-current biasing

texts:
I try to study the output impedance of a JFET amplifier biased by a current source, but I can't do it.
I know how to determine the output impedance of a JFET amplifier polarized by a voltage divider, but I am hampered by the current source.
How can I do it?


texts: How to use HX711 module with PIC microcontroller?

texts:
I'm trying to use the HX711 to capture the weight of a load cell using the PIC18F4520 microcontroller.

According to the datasheet (http://www.dfrobot.com/image/data/SEN0160/hx711_english.pdf) if I put the clock pin (PD_SCK) at GND, the module will activate its internal clock, so simply read what leaving the DOUT pin. Is this right?

If this are correct, I have to connect this output to an analog port?

(Sorry my english)


texts: Identify/substitute Watson capacitor values

texts:
My ceiling fan is not spinning up properly any more. A quick google results in the solution "replace the capacitor." However, the values on the capacitor are not very explicit.

Watson
AC450V
0.5 + 0.8 +/- 5%
T85

My guess: 450VAC, 0.5µF and 0.8µF with a tolerance of 5% and a temperature rating of 85 degrees.
Am I correct about the µF, or are these nF? What wire is connected to what µF?
It seems that I can't find this exact capacitor, nor easily find a different one with two wires with these values. Can I substitute this one capacitor for two separate capacitors, or is there some other way for me to obtain the correct type of capacitor?
Note: I'm located in The Netherlands (Europe), so e.g. eBay has limited availability.


texts:
First of all, I'm new to this forum and I'd like to introduce myself: my name is Julio and I'm an industrial engineering from Spain.

At this moment, I'm doing some research about power calculation (P, Q, S, power factor) with real data obtained from a star connected three-phase generator.

I'd like to compare the results of this power calculation from different theories: p-q theory and an algorithm I've found through which you can calculate power on transient and permanent state.

As I've said before, I'm using real data, so the signal isn't perfectly sinusoidal, it contains harmonics. The voltage captured is line-to-line voltage, so there shouldn't be third harmonic:

va(t) = sin(wt)+sin(3wt)+sin(5wt)+sin(7wt)+...

vb(t) = sin(wt-2*pi/3)+sin(3wt-3*2*pi/3)+sin(5wt-5*2*pi/3)+sin(7wt-7*2*pi/3)+...

vline(t) = va(t) - vb(t) = sin(wt)+sin(5wt)+sin(7wt)+...-sin(wt-2*pi/3)-sin(5wt-5*2*pi/3)-sin(7wt-7*2*pi/3)+...

sin(3wt) is on phase with sin(3wt-3*2*pi/3) and then it cancels out, just as every 9th harmonic, and so on...

But when I analize my data, there is third harmonic.

I suppose that in real data third harmonic isn't canceling out totally, because the third harmonic on va doesn't have exactly the same amplitude as vb.

My question is: which would be the correct way to go from the line-to-line voltage empirically obtained to a phase voltage which I can use for power calculation?

I assume that the data from the third harmonic should be lost if you've measured line-to-line voltage, because it should cancel out and then you can't obtain the phase voltage from the line-to-line voltage perfectly (you will obtain a phase voltage without the third harmonic).

My idea here is to decompose line-to-line voltage on its harmonics, then apply their respective corrections (abc sequence, acb sequence...) and finally sum them up. This way I should have a phase voltage without 3rd harmonic, but I think that's the best I will obtain from a line-to-line voltage, right?

Does anyone knows if there is a research about this? If there is, I couldn't find it.

Thanks for your help in advance, much appreciated.


texts: How to make hex file for attiny402 microcontroller using winavr

texts:
I have written a code in the 'Programmer's Notepad' of winavr. But when I went to make the hex file, I didn't find the attiny402 microcontroller in 'mfile'.

Can anyone help me? Now, what should I do? it is very urgent for me.
thank you


texts: How can i externally power 5 micro servos and one mg996r?

texts:
I am building a robotic arm with 5 * SG90 9g micro servos to flex each finger and one MG996R servo as an elbow joint.
The servos were working inconsistently, with not enough torque and jittering a lot. After doing some research i soon realised that using the 5v supply form the raspberry pi was a terrible idea.
I've tried looking for ways to externally power the servos but i've just ended up more confused than i was before.
I like the idea of using AA battery packs rather than an external wall adapter.
The question is: How many batteries would i need to power all servos (possibly simultaneously)? Maybe a few 4*AA packs in parallel?
SG90 9g Micro Servo: Operating voltage = 4.8v
MG996R  Servo: Operating voltage = 4.8v - 7.2v
Any help is appreciated.


texts: How does aluminium foil or esd foam protect ICs from esd damage when stored

texts:
I see people storing ICs in plastic containers with aluminium foil or ESD foam on the bottom and then put their ICs on top of it to prevent ESD damage.

I dont understand this concept tbh and im confused also, how does it prevent ESD damage ?

My understanding so far:

Plastic is an insulator and insulators store/accumulate charge when rubbed against other insulators. So if the ICs inside the plastic container rattles around, it accumulates charge, this charge cant flow anywhere, then if the potential difference between the IC and the plastic box is high enough it discharges, this could cause damage.

Right so far ?

Ok now putting something conductive between the IC and the storage box solves this problem, but how. What i dont understand is how does it prevent ESD, since aluminium foil is conductive, doesnt it pass the charge to the IC when rattling around ?
Makes no sense to me..
The foil is touching the plastic bin and the IC touches the foil, so still everything is connected together or not ?(the IC is still in "direct" contact with the plastic since the foil is conductive )

For me, it seems, its the same like without foil. So how does it work.

EDIT: That foil/foam only prevents ESD damage inside the storage container but not for when i grab the IC, right ?


texts:
I have some quality earbuds that have no sheath on the wires, because the copper unwinds all by itself, it's held in some thin nylon loose fibres that acts as the insulating material.

it's seems very difficult to work with. what is it? how do i solder it and prevent the wires from unfurling as they arent properly sheathed?


texts:
The solder fillets around the base of the header pins are almost flat - very different from the kind of fillets you'd expect to around a 0.1" header. These kind of fillets are very common on ST's evaluation boards. By the consistency of the soldering, it look like it has been done on a machine. I am interested in knowing the soldering technique involved in this.

Kind of fillet you'd generally expect to see:


texts: How to protect microcontroller board 1-wire from accidental +12V connection?

texts:
I'm working on modular LED strip driver with one "Master" board and up to 32 "Slave" boards. Each "Slave" board drives one LED strip.
All boards have 3 pin terminals:

+12V (connected to 50W source)
1-wire bus
GND

Everything will be connected in parallel (+12, 1-wire, GND).
I'm using WAGO connectors. I'm afraid, that someone will accidentally connect +12V wire to 1-wire terminal and everything connected to bus will be destroyed.
How can I protect microcontrollers from +12V on 1-wire bus?
Im using PIC16F in "Master" board and PIC10F in "Slave" boards.


texts: Calculation of a capacity in the phasors domain

texts:
The circuit operates in sinusoidal regime.

\$V_e\$ operates at 50 Hz frequency.

The eff. voltages (rms) of \$V_e\$ and \$V_a\$ are, respectively, \$100\$ V and \$50\$ V.

simulate this circuit – Schematic created using CircuitLab

I tried to solve it with 2 methods:

First method - phasors diagrams

\$I=\frac{V_A}{100}=\frac{1}{2}\$ A

simulate this circuit

So \$|V_C|=\sqrt{V_e^2-V_A^2}=\sqrt{100^2-50^2}=\sqrt{7500}=50\sqrt{3}\$

Now: \$|V_C|=|\frac{1}{jwC} I|=\frac{1}{wC}|I|=\frac{1}{wC}\frac{1}{2}\implies C=\frac{1}{2\omega|V_C|}=\frac{1}{2\cdot50^2 \sqrt3}\approx115.47 \mu F\$

Second method

\$V_C=V_e-V_A=50\$ V

\$I_R=\frac{V_A}{100}=\frac{1}{2}\$ A

\$V_C=I\frac{1}{j\omega C}\implies C=\frac{I}{V_C\cdot j\omega}=\frac{\frac{1}{2}}{j 50\cdot 50}=0.0002j\$ F

Why is in this case \$C\$ a complex number?

However, in both cases, the result appears to be wrong, since the solution is \$18.38 \mu F\$.

Could anybody explain-me where I am wrong with the two ways, please?


texts:
I am setting up a fast I2C communication between a microcontroller (STM32, master) and an FPGA (Zynq-7000, slave). Currently, it won't work correctly because whenever the FPGA pulls down SDA, it causes some interference on positive clock pulse of pulse of SCL. This results in the FPGA detecting clock edges whenever it pulls down SDA and the clock pulse is positive. See the picture below.

I tried to solve this problem by making the wire shorter and by adding a capacitor between SDA and ground. It works better now, but it still won't work always since there is still a little interference. See the picture below.

Do you know of an easy solution to decrease the interference even more? I tried adding a larger capacitor, but this results in the SDA becoming to slow, and therefore, it will not be detected in time. I cannot make the wire any shorter than the current length.
The I2C communication operates on 3.3 V and the frequency of SCL is 400 kHz. The I2C lines are pulled up at the microcontroller side with 1 kΩ resistors I cannot replace there resistors, but I can add some if necessarry. The wire is a 28 AWG ribbon cable with length of 50 cm (20 inch).


texts:
I was wondering why many generators ect. have 50 ohm output resistance.

Before you answer here is what I know:

Many transmission lines are 50 ohm, and terminated with a 50 ohms load to get maximum power transferred to the load and minimize reflection. So for the load it is obvious why 50 ohm is needed, but why for the source?

I would get more power transferred to the transmission line (or load), if the source impedance was say 10 ohms.

Is it to cancel any reflections hitting the source from the load?

Or does it just mean that the source has been matched to 50 ohms load?

EDIT:
After searching google for hours, I found this link which explains my question:
http://users.tpg.com.au/users/ldbutler/OutputLoadZ.htm

Conclusion: It usually means the source has been matched for 50 ohms. Sometimes in precision signal generators (not RF power amplifiers), the source has 50 ohms input impedance, this is to cancel re-reflections hitting the source from the load. But for RF power amplifiers and etc., the output has been matched for 50 ohms, since half the power would be lost inside the equipment, if the output impedance was actually 50 ohms.


texts:
I would like advice on a potential new set up I am looking at installing in my home.

I have a small water heating system that runs @ 150w 24v DC, I intend to use the solar to power the heating system in the day (or sunny) but at night would like a standard AC/DC psu to power the heating so essentially a constant feed one way another with the solar taking priority when it can.

1) How would I achieve this?

2) Could I use a standard solar regulator and plug the AC/DC psu into the battery terminals?


texts:
For a project I'm making I need to control a chip that works on 3.3V and my PIC who sends the control signal works on +5V so I need to downgrade this voltage so that the signal is not to high for the chip.
I did this with a simple voltage divider, but because my chip needs to have a certain default state I also need a pull down resistor to provide this.
Is this the right method how I did this? Or will this cause problems?


texts: Is there a difference between specialized audio amplifier and general op-amp silicon?

texts:
I've been doing some research into creating a DIY audio amplifier from line-level inputs to speaker level power. I found a guide centered around the LM386 Low Voltage Audio Power Amplifier on YouTube here.

I have a fairly large collection of DIP package TTL logic and alike that I inherited from my father, which I am hoping to make use of in this project. I did some research, and it appears that the LM386 is just a specialized op-amp with desirable characteristics for audio signal amplification.

I located an LM324N op-amp in my collection, which looks to my incredibly untrained eye to have similar characteristics to the LM386. However, seeing how I have a rudimentary understanding of circuit design, it is highly likely that I'm missing some critical information that would allow me to see that the LM324N wouldn't work for my application. Am I missing something, or would the LM324N work fine?


texts:
I am using below diode in my design to protect 3V3 lines:-

http://www.ibselectronics.com/ibsstore/datasheet/AZ5123-01F_Datasheet.pdf

On page 2 they have given :-

Also, they have given on same page :-

What is the meaning of this!! What is +-16KV & what is the 7V??


texts: What components can be damaged through 10KV ESD?

texts:
I'm designing a circuit which has Voltage regulator(IC), current source(IC), resistor, capacitors, LED, reed switch and capacitor. It has to survive 10KV ESD event.

My question is:
1) What components should I protect with spark gap and TVS diode?
2) How can I achieve this? Use both(spark gap and TVS diode) or just one?
3) Any other things I should consider in my design for the protection?

Update:
ESD standard/model to follow : IEC 61000-4-2

Circuit has to survive the ESD event at all the points in the circuit including at the connector where it receives the power.

Thanks in advance.


texts:
I am using DPSK modulation on my signal and want to couple this onto a DC-signal. How will the hardware be set up for this? Is it enough to just couple my signal through a capacitor on to the DC-line?

EDIT:

The AC impedance between my DC and ground should be quite high, having no decoupling capacitors or the like at the moment. This may be altered at a later stage.
My carrier frequency is ~110kHz, available bandwidth between 90-120kHz, using OFDM to utilize the band as much as possible and to avoid noise. This is done using the G3-PLC standard.
I do not know the impedance of my load at carrier frequency, since I will try to just communicate directly between two modems which I will design for impedance matching later with no extra load on the line.
I found that putting a series inductance in front of my DC power supply should be used as a choke for the high frequency signal.

EDIT2:

Will this circuit make more sense?

The sensor will also be able to couple its signal back on to the DC line, and both sides of the line should be able to send and receive data. The receiver part is not drawn in because I don't know how I would do it.


texts: Square wave to sawtooth wave using two BJT

texts:
I have two circuits that are supposed to be square wave to sawtooth wave converters:

Both circuits receive a positive square wave as their input and generate a positive sawtooth as their output. Do these circuits actually work? What are the modes of operation of the transistors? I need to know these in order to set up the equations for calculating the component values.


texts: What is a #delay inside a synchronous process used for?

texts:
I came across a synchronous process similar to this today, and immediately noticed the presence of the #delay:

`define dly #1

always @ (posedge fpga_sysclk_b or negedge reset_l) begin
    if (!reset_l) begin
        mv_in <= `dly 'h0;
        mv_datai <= `dly 'h0;
    end
    else begin
        mv_datai <= `dly mv_dataix;
        mv_in <= `dly mv_datai;
    end
end

What does this achieve? Since the process is already synchronous to the clock, I don't understand why it is necessary.

Is this synthesizable? my understanding is that #delays are not synthesizable, is this the case in this instance too?


texts:
We have 3 measurement system and a master computer. Only the master computer have access to the Ethernet because of this we would like to use WiFi connection, but for this purpose I have no idea which part fits the best. The measurement systems are 500m to 2000m away from the master. I found this solution but one of this is cost around 850Euro.

I have no idea where can I buy the antenna and the modules and which does it fit to this purpose.


texts: Selecting the right battery type and capacity

texts:
Have a machine in mind which is intended to be portable (hence weight and dimensions is a constraint), has a miniature refrigerant compressor (like those of Aspen) plus a blower of nominal wattage. Furthermore, the machine is desired to run on rechargeable batteries and give a backup of at least 8-10 hrs. Hence the primary power consuming thing is compressor itself. Following are the specs of intended compressor

Capacity: 360W
Input: 12V or 24V or 48V (3 models)
Max. Current: 9.5A, 9.5A or 7A respectively
(Add-on info: Weight: Around 0.5KGs just)
Battery Backup required: 8-10 hrs continuous operation but will have compressor trip-outs in between.
Rechargeable Battery: Yes
Battery Cycles: At least 100 cycles will be good.
Desired cost: Off course minimum
Desired Weight: Max. 4-5 KGs??? or what's the minimum I can get?

I don't know much about batteries, this is my first encounter. Have read quite a lot on net and stack but wanted to have exact and precise information rather than my not-sure-calculations as the whole idea depends on this battery thing.

So considering the current world of batteries, is it even possible to have a practical battery solution for this scenario? Because weight of battery and size is the biggest constraint. It should not be so heavy or bulky that it renders the equipment non-portable. I assume that for very accurate answers, more information on compressor (like current drawn in its tripped condition, if it just slows down instead of stopping etc is required but considering the given data, you can suggest a direction at least and approximate answers)

What can be the optimum battery type which I should search for? Liquid, Gel, Dry or anything else? 12V or 24V? Please suggest any brand or model too if possible so that I can find the supplier and evaluate the cost. What should be the capacity? (I have figured out that it should be around 300Ah, on 400W load (assuming an FOS, correct me if I am utterly wrong.)


texts: Controlling a Brushless ESC with Arduino

texts:
I read this is possible here:

How to drive brushless motor with Arduino?

I'm just getting started with Arduino and electronics in general, can anyone recommend a tutorial or guide that could serve as a starting point for how to approach controlling a brushless ESC with an Arduino?

I can't seem to find much information about how a brushless ESC even works, let alone what it will take to use an Arduino to communicate with one (or more).

Thanks in advance!


texts: Sensor to distinguish between daylight and artificial light in a room?

texts: is there a way to distinguish between daylight and artificial light in a room? I'm thinking my options are a light intensity sensor or a color temperature sensor. The sunlight is supposed to be much stronger than artificial light. But I'm wondering if the case will be the same inside a room. Or does the idea seem silly to distinguish between both?


texts: Is it possible to induce RF Emissions from a RF enabled Device

texts: Would it be possible to take a device anything such as a wireless router or a wireless video and induce unintentional RF emissions while no power is supplied to the device ? Can you send it some range of RF waves and attempt to measure the RF emissions due to incidental waves (re-radiation) ?


texts: Analyzing a circuit with 2 voltage sources

texts:
This is a problem given to us for homework:

This is the first question I've got that has 2 power sources and I'm stuck on calculating the potential difference and current through R3, R4, and R5. I first thought to combine the voltage from both sources and use it to calculate the current and voltage across R3 but then I get stuck with what to do for R4 and R5.


texts: the sound from the coil when the current is drawn

texts:
I have buck-boost converter using a TPS630250(4.2 ->Vin) - (3.3 -> Vout) in my PCB. This buck-boost converter can draw max 4A in buck mode and max 2A in boost mode.
While there is no load or there is light load ~150mA) in my PCB , My converter nicely keeps working. When I try to draw about 1A from LEDs (that I can not draw current), I am hearing sound from my inductor. Also, Output voltage of converter decreases to about 2.8V.
I sure from my soldering. I sure current from capacity of my power cable.
I am sharing with you my schematic and related datasheets. I wonder your comments and advice.
My inductor datasheet : https://cdn.ozdisan.com/ETicaret_Dosya/516756_635936.pdf
My converter datasheet : https://www.ti.com/lit/ds/symlink/tps630250.pdf?HQS=dis-dk-null-digikeymode-dsf-pf-null-wwe&ts=1621014133772


texts:
I was reading about the duality and complementary relationship of analysis and syntesis bank when a multirate signal is decomposed into its subband components.
I am trying to understand the concept behind why exchanging these two of a perfect reconstruction transmultiplexer generate another perfect reconstruction transmultiplexer.


texts:
Hello i have an op amp shown here:

If i connect a speaker to the output of it the audio signal is amplified.
So far so good. But if i connect an LED to the output of the amplifier it doesn't turn on.

And if i feed a comparator from amplifier's output, and connect the LED to the output of the comparator this time the LED turns on.

What is the function of comparator here? Why doesn't LED turn on just after the amplifier?


texts: Overcoming a wire's internal resistance?

texts:
Let's say I have a very sensitive device that needs EXACT voltage.  Let's say that the voltage it requires is 5 volts.  Now let's say I'm running the aforementioned voltage over a wire with an internal resistance of 20 ohms.

How many volts do I need to put into the wire to ensure I get 5 volts out?

Based on my rudimentary understanding of Ohm's law, I would say 5 volts / 20 ohms = 0.25, so I need 5.25 to overcome the wire's resistance.  No idea if that's right or not though.

Edit: The current drawn will be anywhere from 1 to 2 amps.


texts: How is it possible that emitting electrons create alternating charges in the cavities of a magnetron?

texts:
In a magnetron, electrons are emitted from the cathode and create alternating charges in cavities (fig). These alternating charges produce oscillations in the cavities which result electromagnetic waves.

I know the working of magnetron but I dont understand how do the emitting electrons create alternating charges in the cavity.


texts: RC Joystick Question: What is this component?

texts:
I am a electronics novice and I had a question regarding a small RC project I am working on.  I am trying to control my transmitter with a raspberry pi.

The RC unit is a twin electric engine boat. The RC transmitter is very simple. There are two joysticks that move in only one direction (UP or DOwn). Center position engine is off, as you move the joystick forward, the engine moves forward. If you pull the joystick back, the engine goes in reverse.

When the joystick unit is taken apart, what you have is a double metal spring plate that each is over some sort of coil or resistor. I have taken a picture. I am not sure what the component is in this picture and that is the first question: What is this component?

I have added a blown up pictures of the component here as well

Analysing the joystick switch and joystick circuitry, there are three wires going to the joystick(blue, black and yellow). The middle (black) is ground. Checking the voltage with a voltmeter after having confirmed which wire is GND, I get  -3 Volts on each of the non GND Pair (blue and yellow) when checked against GND. I am a little confused about the -3 volts. How do you get negative voltage? I understand if you get the GND and positive reversed, but  I confirmed the GND wire was indeed the GND.

If  you move the joystick forward one of the metal strips moves closer to the component and the voltage on the blue wire moves closer to zero while the yellow stays at -3V. At max forward, the voltage is zero on blue and -3V on yellow. If you move the joystick back to center, both are at -3V. As the joystick is pulled back, blue stays at -3V and Yellow heads toward zero. Again at Max joystick back, the volt value is zero.

Second question is about the -3 volts and how that is achieved? Can someone explain how this circuit is working to me? The -3 Volts is what is throwing me...


texts:
I have put the following circuit together using a LM348 which is described as a Quad 741.

It works perfectly using a 0-5V source. It only requires 1 op-amp so I had a 741 kicking around and wired this in. The circuit is a ramp so if you apply 5v to vin it will ramp up based on the RC circuit, when turned off it will ramp to 0. With the 741 it only ramps down to around 1.8 V not 0. If I remove the op-amp from the circuit the inputs are 0v so the feature is within the op-amp.

The difference (apart from multiple op-amps) between the 348 and 741 is the offset adjustment pins. The voltage seems too large for this adjustment, I just have them floating in any case.

Why would the output not be 0v?


texts: Vacuum Fluorescent Display: What are the benefits of an AC filament driver instead of DC?

texts:
Question is already in the title:
What is/are the benefit(s) of an AC filament driver instead of DC for VFD displays?
It works with DC so why to invest in an AC driver?
Anyone?


texts: Operating multiple low power devices from 1 adapter

texts:
I have 3 WRT54G routers (12V), 1 voip gw (9V), 1 cable modem (9v) and a gbit ethernet switch (12v) which are all operating from their own adapters.

I planning to build a low power (probably 12V UPS) later on not just to power these but to power some computers through X3-ATX-300 300 Watt High Power 24pin DC-DC ATX.

As I understand transformators are all lossy especially these cheap power adaptors which these devices come with from China.

What I really care about is that the Watt consumption at the end. I realize it's not possible to calculate this in advance how much would I won with the switchover since that wattage shown in the devices datasheet is the possible maximum or not even an accurate data. The only way to see how much will I save with this is to use a powermeter plug all the adaptors into one electric switch which is connected to the meter then do the same thing with my all-in-one adapter.

How should I go with calculating how many amps max will my all-in-one transformator needs to provide?

Looking at these big brick power adapters for the WRTGs:

http://www.abrahamarama.com/wp-content/uploads/2007/08/linksys-ac-adapter.jpg

One can do 1Amp, I think it could easily power all 3 routers for example but I want to go for sure. How to calculate what powersupply will I need and which one should I buy which is the most efficient?

Thanks!


texts:
I am planning to use a differential amplifier, LTC6409 which is reported to have a GBW of 10GHz. I ran an AC analysis on LTSpice using the Spice model given here. I connected the negative input to ground and the positive input to an AC source. The result shows that the open loop gain reaches 0dB at around 2GHz.  The open loop gain at 10GHz is around -27dB.

As far as I understand, I can add feedback and have a flat close loop gain of 0dB up to 2GHz, but it is not possible to have a closed loop gain of more than 0dB beyond 2GHz.

Now I thought of three possibilities

My simulation or my understanding of the concept of GBW is incorrect.
The Spice model of the op-amp is incorrect
The reported GBW is incorrect (I hope not!)

Can anyone please help me understand this? Any suggestion for other differential amplifiers with GBW of at least 5GHz would be great.


texts: Reading a negative and positive voltage from an STM32F4 ADC

texts:
I'm working on an application which requires me to read a curve on an analogue signal. Depending on external influence the curve could either be a negative voltage or positive voltage. The shape of the curve doesn't change so it's effectively a direct inversion. The ADC of the STM32F4 that I am using has a Vref- that must be tied to Vss ie. ground (vref+ is currently 3V3 but I'm planning to reduce that when I get around to it). The ADC is currently configured to 12bits @ 1Msps. I'm taking 30 samples for each time i get a signal at the indicated point.

My problem: I can read Potential Signal 2 fine, it is within my ADC reference voltage. I cannot read Potential Signal 1 as it is outside my ADC reference voltage.
Solutions: I was initially just going to add a DC offset of 0.7V or so with a 5V rail that I have but ripple which may be present on the supply (LM78L05) could affect my reading as I am currently converting with an approximate accuracy of 800uV per bit.
I've also considered configuring the ADC to use two channels. One channel would be connected to the signal via a low gain inverter  (this would flip potential signal 1 and amplify it a little) and channel 2 would be connected to the signal via a low gain non-inverting amplifier. I'm thinking that I could do this with a 2 Op Amp package and with precision resistors for the feedback loop.

simulate this circuit – Schematic created using CircuitLab
I could then use software to determine which of the two possible signals is the correct one (eg. potential signal 1 would mostly read a zero in ADC channel 2 but would look correctly inverted on ADC channel 1).
Does this make any sense, is there a simpler way to do this? My biggest issue is that my accuracy needs to be quite high, in the region of 100s of microvolts. Would voltage ripple present on the supply for the op Amp affect the output?
Idea number 2 inspired by @Rohat Kılıç's answer:

simulate this circuit
As I was initially concerned about adding an offset because of the potential added noise/ripple from the power rail, could I stick with the idea of using 2 channels of the ADC, add the same offset to both with the signal only being present on channel 1 and then channel1 - channel2 to remove the common noise?
thanks for the help


texts: Would replacing a 3.7v 1000mAh lithium ion battery with a 3.7v 5000mAh lithium ion batter make my projects last longer between charges?


texts: Galvanic Isolation in Automotive Environment

texts:
I am using a linear regulator (MIC29302WU) to power a computer mounted inside my car; however, there is significant noise being passed along the ground of the regulator to the main computer. I verified this by connecting an inverter to the battery and using a 12v power supply which eliminated the noise.

Can anyone suggest an isolation circuit? I would like to consider cost and board area. Would this require a flyback design? Or can I get away with not using a transformer?


texts: Estimate minimum discharge voltage in a laptop battery

texts:
The objective is to determine the best 18650 cells to replace the ones in my laptop battery.
To do that, I need to know the minimum voltage the battery controller accepts before ordering the OS to shutdown the laptop. So, I have discharged my battery until the laptop refuses to turn on. I opened the battery case and measured the cell voltages:
Cell#1: 3.427V | Cell#2: 3.331V | Cell#3: 3.421V
These voltages were measured under no load (battery disconnected). I think the minimum voltage the controller accepts under load must be slightly lower than the ones measured. Do you have any idea how to estimate them?
Just to be sure I am not making any other mistakes: I have estimated the discharge current around 2-3A, which means 22-33W under ~11V (typical laptop consumption). Does that seem correct?
Finally, I checked the voltage when the battery is 100% according to the controller, and I got voltages around 3.85V per cell. I found this a little odd, as I expected something closer to 4.2V. Maybe this is due to the deteriorated state of the cells?

EDIT: Apparently, the battery controller is still calibrating itself after a full discharge. Right after I measured the 100% charge voltages, on the next boot the battery percentage went from 100% to 75%. I have remeasured and the voltages are around 4.05V, which are closer to 4.2V.

EDIT2: I tested the battery under load until the controller turns off the laptop. The voltage in each cell was around 3.2V, oscillating greatly due to the "knee" region Bruce Abbott mentioned.

EDIT3: I plotted Cell#2 voltage vs. time while charging:

What Filek said is indeed correct, the controller does not go to 4.2V, it stops at about 4.06V.


texts:
I am trying to create a pulse voltage source in ltspice. The pulse should look like a half cycle of a sine wave however the rise and fall times should be different. I can create such pulse with the PULSE function of ltspice and can create a half cycle sine wave but I don't know how to create a nonsymmetric sine pulse. The rise time should be 10 microseconds and fall time should be 15 microseconds. I added a picture that I drew for you to visualize.

Thanks in advance.


texts: Power a large solenoid from a microcontroller?

texts: I am trying to control a large solenoid, rated at 10 Amps and 12 Volts.  I am trying to use this mosfet, however I keep burning them out.  I have a rectifier diode connected across the solenoid, and I am powering the whole circuit from only 7 volts.  How do I prevent the mosfets from burning out?  My circuit is like the one below.  The diode is a 1N4007.  I have a heatsink on my mosfet.


texts:
I am looking for a way to redirect 6 pcb traces with a push of a single button.

There is micro controller with a SD card connected and I would like to access the SD from a computer without needing to take the SD card out.

The plan is to use a SD card reader and solder wires to the pads inside and connect that with a 6 way cable plug. I would then need to disconnect the PCB traces going from the micro controller to the SD card so that it wont power up the system with 3.3v from USB.

Is this possible?


texts: Need to operate ac appliances using 5V, 10A relay module with ESP8266 node MCU. How to do it. Please explain the schematics elaborately?

texts: I am having problem in triggering the 5V relay with the output GPIO pin of ESP8266 node MCU. I think the voltage provided by the output GPIO pin is not enough to trigger the relay. I'm thinking of turning of the a AC operating light using the relay. How to do please explain. Can we replace the relay with any transistor circuit to operate the same? Please explain elaborately with the schematics.


texts:
I am new to electronics so please forgive me.

I am looking at powering a WS2812B RGB strip. Specifically 144 LEDs/ meter. After doing some research I found that 200mA is lethal and can kill. Now, of course, the idea is to not touch the terminals but I just want to have an understanding if this strip could kill me.

I believe each led uses about 50mA and so if we do the math (50*144) that results in 7200mA. I'm not going to power all the LED's at full brightness at once and I may only end up only using around 80 LED's.

I want to use a phone brick charger to power the LED strip (5V and 2A) I understand that this will result in dimly lit LED's but my main question is: Will 5V and 2A kill me if I accidentally touch the terminals or connections?? Considering 200mA is lethal.


texts: Extending the backup runtime of a UPS with an external car battery

texts:
I'm looking for a simple/inexpensive way to have a longer power backup time.
My fist thought was putting 2 cheap UPSes in parallel. But I quickly found it's not that simple. You would need another device that synchronizes the waves, otherwise... boom!!.

Then I thought of connecting them in series, but I read somewhere that that wouldn't work because the output of a UPS in backup mode is not a true sine wave. So feeding a second UPS with that fake wave would make it think the power went off and it would switch to battery mode as well.

So then I thought, what if I could use a car battery as an extension to the UPS' internal battery. And I found this instructable that shows exactly how to do it.

The article gives the important warning that a UPS is not meant to run at full capacity on battery power for a long time (just for the time its battery last, which is a few minutes) so you should choose a UPS with twice as much power as you will need.

Keeping that in mind, is this safe to do?
Is it as simple as putting a car battery in place of the internal one and expect it to work seemlessly?
Will the UPS be able to charge the car battery considering it's way bigger than the UPS is meant to have?


texts: I have a microcontroller that I want to install in my car. One wire coming from the car supplies +12V from the battery independent of whether the car is on or off. This works fine to power the microcontroller when the car is on, but I would like to cut the power when the car turns off. Another pin in the same harness reads about +0.25V when the car is on and +12V when the car is off. How can I use this signal to switch on/off my microcontroller? There are some ideas that come to mind, but I am not sure what type of solution will use the least amount of power when the car is off.


texts: How does power in "wall wart" power supplies work?

texts:
I'm new to electronics and am having trouble understanding how power supplies convert 120AC into a safe, manageable DC voltage. So far, I understand that there's a transformer to step the voltage down, then a rectifier, followed by an IC voltage regulator. However, any way I look at it, it seems that even if you step the voltage down 10x (via transformer), the current going into the rectifier is 10x larger than the wall outlet. This seems dangerous, and also contradicts my impression that wall-power supplies like wall warts produce safe voltage/current.

Am I correct in thinking that the power output from a wall wart is equal to the power output from an electrical jack (IV = IV)? If so, is getting shocked from an outlet equally dangerous to getting shocked from a wall wart? If not, what's missing from my analysis?


texts:
I am developing a data logger with ESP8266 using RTOS SDK and that needs light sleep to be implemented. From this official programming guide (page-36) I have used the following code with the latest functions from esp_sleep.h library.
void fpm_wakup_cb_func1(void){
    esp_wifi_fpm_close();             // disable force sleep function
    esp_wifi_set_mode(WIFI_MODE_STA); // set station mode
    esp_wifi_connect();               // connect to AP
}
esp_wifi_disconnect();
esp_wifi_set_mode(WIFI_MODE_NULL);               // set Wi-Fi mode to null mode.
esp_wifi_fpm_set_sleep_type(WIFI_LIGHT_SLEEP_T); // light sleep
esp_wifi_fpm_open();                             // enable force sleep
esp_wifi_fpm_set_wakeup_cb(fpm_wakup_cb_func1);  // Set wakeup callback
esp_wifi_fpm_do_sleep(50*1000);

But when I run this code, for the functions esp_wifi_fpm_set_sleep_type, esp_wifi_fpm_open, esp_wifi_fpm_set_wakeup_cb & esp_wifi_fpm_do_sleep, it prints an error message: "FPM: We have removed this api, please do not call". But I could not find any alternate sleep functions. So how can I implement light sleep on ESP8266 with RTOS SDK?


texts: Program for simulating circuits on linux

texts: Do you know any program that works on linux and can simulate complex circuits?


texts: understanding the datasheet of a normally closed / changeover reed switch, for powering Arduino project

texts:
I am working on an Arduino project that should be sealed, with the possibility to switch off when the user wants. A solution I have seen on commercial products is the use of a Reed switch, normally closed. When there is no magnet, the board is powered on. When the user adds a magnet at a given location on the box containing the electronics, the board is powered off.
I have been looking for such components online, but I have a hard time finding tutorials / explanations for Reed switch n00bs like me. So what I need is some help understanding a datasheet / understanding if what I think about will work.
My speccing needed:

range of operating temperatures: -40C to 30C (this is important, polar environment use! -60C would be even better, but that seems hard to find).
switching on and off electronics working at 3.3V
max power draw by the electronics: up to around 200mA
way to close the reed switch: by using a small rare earth magnet (these are surprisingly strong, but I do not have a spec available), through a plastic wall of approximately 1.5mm thickness.

After searching online I am considering this switch: MDRR-DT Series https://www.littelfuse.com/products/magnetic-sensors-and-reed-switches/reed-switches/mdrr-dt.aspx .
I like it better formed (i.e. F version, less risk to have the 2 legs getting in contact). I am quite unsure about which sensitivity to use though. I want to be sure that it is not too sensitive and does not close unexpectedly, but I still want to be able to close with my quite powerful rare earth magnet. Should I go for something like 25-30AT then? That would be like this: https://no.mouser.com/ProductDetail/Littelfuse/MDRR-DT-25-30-F/?qs=nyo4TFax6New9CGWZwJeTA%3D%3D .
Anything I am not thinking about that is important when considering using Reed switches for such applications?
Edit 1:
What I am confused about is in part why AT is given as a range. Does AT 15-25 well mean that the switching is happening somewhere between 15 and 25, or that at above 25 weird things happen?


texts:
I was looking at this site and saw the term. While I'm a bit familiar with some DSP terminology, I have never heard of this before. Google did not really help at all.

From what the site explores, it seems like it's either a type of filter, like IIR or FIR filters, or an algorithm like the FFT. The site, however, does not focus on DSP but focuses on computer science.

Any ideas? Would it have something to do with thresholding?


texts: Difference between transfer gate and NMOS switch in CMOS image sensors

texts:
I would like to know the difference between the transfer gate (TX) which is used in 4T CMOS Active Pixel Sensor (APS) as mentioned in the below image and a normal NMOS switch.

As far as I know, the transfer gate is used for transferring the accumulated charge from the pinned photodiode to the floating diffusion. But, this looks like a switch or an NMOS switch to me, where the gate of NMOS is switched on and the current flows in the channel. However, in the books, I see that the transfer gate is manufactured in relation with the pinned photodiode. Also, this concept of transfer gate was carried over from CCDs, which I noted down, but it was not enough to understand why this transfer gate is not just an NMOS switch.

Any guide/hint on the above would be helpful. Please also correct me if my understanding is wrong on the above and indeed if it can be seen as an NMOS switch. Thank you.


texts: Low-Standby Battery Power Button Circuit

texts:
I return with yet another power switch circuit for an entirely new project! (Yeah I do a lot of robot projects lol)
So basically I designed a circuit to turn on/off a battery-operated device from the same button, with minimal standby power draw (and minimal wires to the button panel itself, which is one reason why I went with LOW side switches). I feel like this is an improvement over my old designs I've built, replacing the one to multiple Schottky Diodes with purely MOSFETS.

It works in a circuit sim, but I'm mainly just wondering if there's any drawbacks/caveats to this design, or if it's pretty solid. And if it's good, hey, maybe the design is helpful to a random Googler or two.
If you're wondering on the specific parts used, I can give them, but they're pretty generic Logic-Level MOSFETS, Resistors, and Zenner Diode, so nothing special there.
Here's a rundown of how it works:

Because the battery voltage could exceed the max Vgs of the MOSFETS (+/-20V), R1 and the Zenner Diode D1 produce a dedicated ~3.3v voltage line with fairly low standby current (theoretically less than switching on the main 3V regulator).
Normally, Q1 and Q2 are off (held by pullup R2 and pulldown R5, respectively). The EN line of the Regulators is held HIGH (Most of these generic regulator ICs tend to use active LOW enable pins, including the ones I selected) via pullup R4, connected to the Diode regulator.
When the button is pressed, the P-BTN line goes LOW (C1 and R3 provide debounce), and the Vgs of Q1 (P-Channel) becomes negative, as Gate is pulled to 0V, while Source remains at 3.3V, which turns it on.
The Drain of Q1, aka the PWR bus, then becomes 3.3V, making the Vgs of Q2 (N-Channel) positive and turning it on. In turn, this forces the ENABLE line LOW, activating the main 3V, 5V, and 12V regulators and powering up the system.
Once the regulators power up, the CPU boots and waits a certain delay before switching on the PWR bus, which is also connected to an IO pin. This IO pin becomes 3.3V and holds the power on, if and only if the POWER button was held long enough.
Finally, the power button can be safely released. This allows P-BTN to return to a floating state. It will then be pulled high by an internal pullup of the CPU (Just an ARM-based Arduino-style prototype board, for now)
When the power button is pressed a second time, the CPU detects it, and after release, the system powers off by releasing the IO pin holding the PWR bus HIGH.

Edit: Did some more circuit simulation and found that making all the resistors 576k instead of 100k works better. I know this is a pretty damn high value for pullups/pulldowns but it seems to be working, in theory, and it'll have really, really low standby current. It actually reads as 0uA in my simulator when off lol.


texts: How can I execute multiple for loops sequentially in Verilog?

texts:
I'm trying to turn on the LED lights on my FPGA Spartan board one at a time until all lights are on and then turn them off in the reverse order. I could easily do this in other OOP languages by making two for loops and slowly change the values in an array with each for loop reversing the other just like in a simple starter Arduino project. However, Verilog executes in parallel therefore I am confused as to how I could make the loops run sequentially. I know that using a blocking and non blocking statements affects the how the code executes but I do not see the correlation to loops.

example:

for (counter = 0; counter < n; counter = counter + 1)
            #7 lights[counter] = 1b'1;
for (counter = n; counter > 0; counter = counter - 1)
            #7 lights[counter] = 1b'0;


texts: Serial newbie: why can't I just hook the wires up?

texts:
I'm trying to transmit from an ATtiny85 to a PC using Arduino-esque code over a USB-Serial converter without understanding very much of anything.  I was shocked and appalled that it did not work.

I confirmed that the tiny is flickering the voltage on one of its pins, but when I connect that pin to transmit or receive on the USB-serial cable and try to listen using a terminal program, I get nothing.

I'm not sure how to tell which part is broken.

  Do I need more than VCC, GND, and TXD to transmit serial?

Details:

The code for the tiny is written in the Arduino environment and similar code successfully blinks all 4 "PORTB" pins, at least according to the LEDs.  I use the code from HLT and Saporetti to let me use the Arduino dialect of C++ to program it.  The program still comes in under a K.

#include <SoftwareSerial.h>

SoftwareSerial s(0,1); //receive on "0", and transmit on "1" aka "PB1" aka pin 6

void setup() { s.begin(4800); } // assuming 1Mhz, 4800 baud
void loop() { s.println(millis()); } // transmit something at every opportunity

There's a lot of translation involved, but the code is pretty basic.  The code that sets the baud rate seems to assume 1MHz, but luckily my attiny has factory default fuses and runs at 1MHz.  At any rate, pin 6 is flickering its voltage according to the LED.

So I use the little wires to connect the "ftdi" end of the FTDI USB-serial converter to the tiny: black to GND, red to VCC, orange to 6.  I open the program "minicom" on the PC, set the baud rate to 4800 and wait, for nothing.  When talking to my Boarduino, it has no trouble.

The FTDI converter cable has the following pinout: black is GND, brown is "CTS", red is VCC (+4.98V), orange is "TXD", yellow is "RXD", green is "RTS".

  If I want to transmit from the tiny to the PC, should I be flickering the voltage on "TXD" or "RXD"?  In other words is the transmit wire to transmit from the slave to the host, or the host to the slave?

I actually tried both, neither worked.  I've fried less than a dollar's worth of equipment so far, and I'm getting cocky, so I just plug wires into the cable.  Maybe I'm not supposed to ignore the "CTS" and "RTS" wires?

  Do I need to use any other wires?  Do RTS and CTS do anything?

The hardware is an ATTiny85-PU (DIP-8 package, running at 1MHz, rated to 20MHz) powered by USB at 4.98V.  The host PC is a MacBook, and it successfully does all things arduino, including using ArduinoISP to program the ATtiny to blink its little heart out.


texts: Can someone tell is this transistor or capacitor or what?

texts: Can someone tell me what is this ? what kind of transistors is this ? and what does it called and i need full info about it, forgive my ignorance,


texts: Is it safe to use a 120V/60Hz rated espresso machine on a 100V/50Hz grid?

texts:
I'm new here and my question is a bit complicated with multiple factors, so please allow me to explain it.
I live in Eastern Japan where 100V/50Hz is standard. I intend to use a very expensive 1800W coffee machine that's made in the USA and therefore specified for 120V/60Hz. 100V is definitely below the 92% tolerance.
I happen to have the following step up/down transformer:
https://www.220converters.com/store/p/987-TC3000G-3000-Watt-Step-Up-Down-Converter.html
On the back of the transformer is a plug, which can be set at four different input voltages: 100V, 200V, 220V, 240V
With the transformer plugged into a 100V power outlet, I get the following output readings for each setting:
Plug === [Output 110V] === [Output 220V]
100V === 102V === 203.8V
200V === 56V === 112V
220V === 51V === 102V
240V === 46.9V === 93.5V
Note: The multimeter reads 102V from the wall outlet.
Now with the 100V power outlet switched to 200V, the readings are as follows:
Plug === [Output 110V] === [Output 220V]
100V === n/a === n/a
200V === 112.6V === 225V
220V === 102.5V === 204.5V
240V === 94V === 187.7V
Note: The multimeter reads 203.8V from the wall outlet.
Now I wondered whether it's a good idea to run the coffee machine on 112V. This is still below 120V but at least within tolerance.
Question 1.) Is this safe in the long term (for the coffee machine)? Or would that increase the risk of damaging the motor/pump and the internal wiring?
Question 2.) Is it in general safe to use the intermediary voltages that the transformer generates although it wasn't made for that? Could there be wave distortions that possibly affect the life of home appliances?
What confuses me even more is this article:
https://canadatransformers.com/transformer-frequency/
The author states that 60Hz appliances should be run at 20% less voltage if on a 50Hz grid. If that is true and the difference in Hertz really affects performance that much, I might be better off not using the transformer at all? A quick test showed that the coffee machine seems to work fine at 100V though. What do you think? Am I trying to herd cats?


texts: Hold a SMD chip on the PCB with Scotch tape

texts:
Background: I'm watching many SMD soldering tutorials these days, but I'm still not ready (too nervous!) to actually try it with my PCB and DAC TI PCM5122PW:

Question: Can I put the SMD chip on the PCB and hold them together with Scotch tape during a few hours, and power on my PCB, to test it everything is working ?
Will the SMD chip's pins be in contact with the PCB pads, if just held with Scotch tape?

Note: I'm not asking about using adhesive tape to hold the SMD chip for soldering purposes, but really for having, during a few-hours, real contacts between PCB and SMD chip.


texts: Arduino - receive Ethernet W5100 signal to multiple arduinos

texts:
I'm after doing a device in which I'll use 4 AtMega328 chips; Since they'll all be mounted on the same PCB, and I need an ethernet connection for them, I was wondering if there's a way to share the ethernet signal from the WizNet W5100 shield to all 4 of them?

Note, I will only need to receive the signals, which is broadcasted anyway, and I have the code inside of each 328 which knows what data to read and what to ignore; So basically, the same data could be delivered to all of them, but I'd like to avoid the need of having a) stupidly 4 ethernet shields + ethernet switch inside or b) less stupidly (but still) another 328 to receive the data and forward the data via serial Tx/Rx chained through all other chips...?

I know they only have one pair of serial interface, but since I only need to read the data, I could use the Tx to link to another's Rx with no issues.

I was just wondering, if is there a way to split what's coming out of WizNet IC or not...?

I know it connects via ICSP header normally, but it's using digital pins, not the actual ICSP, if I'm not mistaken, right..? So, could it possibly work if I'd steal the signal off those pins and just parallerly link them to others...?

And to answer the plausible question asked: No, it cannot be done via one of the ICs directly and forwarded via serial. If this is the way, I'll have to add another 328 to take care of that. If I can avoid that, however, it would be awesome.

Thanks


texts:
I am using a circuit to drive high voltage display tubes (170V DC, 3mA).

Currently, the tubes get switched by an arduino. The output pin is hooked up to a MMBT42 transistor and a 10kOhm base resistor.

I want to use a PCB, with 80 of those lamps. So I need at least 80 transistors and 80 resistors, which is is a lot of work to solder the parts.

Now I wonder, if I could replace the resistor/transistor with this mosfet because the mosfet does not need a resistor.

This BSS131 is a logic-level Mosfet, according to the datasheet.

Would this suit for my application?


texts: What would you call a cable which combines both a coaxial transmission line and regular conductors?

texts:
I'm looking for a cable that can carry both dual supply (+5V and -5V at <100mA) DC power and a relatively high bandwidth analog signal. The intended application is powering the amplifier of an active probe.

Problem is, I don't know what to call such a thing, so I have difficulty finding anything. Is this such a niche product that realistically you have to custom order it from a manufacturer at great expense? I did find out that some shops specializing in CCTV equipment sell RG59 with two extra power conductors attached as "siamese coax", but that term seems to be exclusively used in the context of closed circuit television.

To be clear, I'm asking for clarification regarding terminology, not any specific products.


texts: Verilog parallel CRC with arbitrary polynomial

texts:
for my next project I need to implement a CRC IP core in Verilog HDL. It must use 16bit polynomial and 16bit CRC result register. Data is being fed into it in 8bit chuncks / bytes. I have allready implemented serial version of CRC core, using a shift register and xor gates, but I'm completely lost in how to do it in parallel, so that the result is available at the next clock cycle ?

Best regards


texts: Are there resources for learning to write drivers?

texts:
I have a decent amount of experience designing hardware and embedded systems in general, but I have never written a driver for an operating system.

I would like to know if there are any good guides, preferably online, although good books would interest me, that will give me a good start on what I need to know to design and implement drivers for an operating system.

This will probably have people shooting at me, and although I would love to see a good guide no matter what OS it is based on, I would like to see a guide that is windows based, mostly due to the fact that most of the people I would sell a product would have windows.

Please let me know if there is any extra information I can add to make this more clear.


texts: Will a system necessarily have an increase or decrease in power factor with a change in frequency of the system?


texts: H-bridge using solid state relay instead bootstrap IC

texts:
experts! Good afternoon.

I am working on a project using a H-bridge. It must work at 100V and, then, i first designed a bootstrap circuit with 2 IR7304S (attached picture). Then i was wondering if two solid state relay could perform the same thing, replacing the bootstrap circuit and removing the MOSFETs. The objective is to let the current through the load to be bidirectional.

The switching frequency is quite slow (200Hz) and the load current is about +-70mA.


texts: How to wire the REF200 IC for a 100uA current output?

texts:
I am trying to create a 100uA constant current source to power a homemade sensor. I bought a few REF200 ICs http://www.ti.com/lit/ds/sbvs020/sbvs020.pdf since each has two 100uA current sources. Problem is I'm getting only 7uA for each of these sources, so my wiring must be wrong. How do I wire this correctly? Are there better options to create a ~100uA current source?

Here's what I did:
pin(8) to +5V (power supply)
pin(1) to the sensor and from the sensor to my power supply GND
Added a multimeter in series to measure the current.


texts:
Edit: Pretty much all conjectures in my question have been proved to be incorrect. I started fresh with a new approach. New question is here.

Original question:

I'm having an issue with a touchscreen LCD assembly.

The touchscreen normally works fine, but if I mount it in a housing with a gasket the taps sometimes register in the wrong location.

The incorrect taps only seem to occur when I'm tapping the screen. They don't occur on their own.

This is the screen I'm using: NHD-4.3-480272MB-ASXV-CTP (note the thumbnail is inaccurate)

I've tried different gasket materials such as neoprene rubber, and foam but the issue occurs with all of them.

Inside view (without LCD)

I placed the gaskets so that there is an ~1mm gap between the LCD active area and the gasket on all sides. The datasheets for this part don't have a recommendation for the gasket material or geometry.

Can anyone suggest a solution for this problem, or design guidelines I might use to come up with a solution?

The housing the screen will be mounted will be injection molded, so it's difficult to modify at this point. It doesn't really have any features besides an aperture, and screw holes for the bracket.

EDIT: New discovery, it doesn't seem to be the gasket after all. I realized that when the touchscreen is not installed, I'm holding it by the bracket and thereby grounding myself. If I set the touchscreen on the table and touch it with only 1 finger, the same problems occur. So, new question why does the touchscreen only work when I'm grounded? The RH is 65% in my office, so I don't think it's static.

EDIT2: I thought the power supply had negative connected to earth, but it doesn't. So I manually connected it, and that fixed the problem. ..But I still don't know why. Why does the touchscreen not work correctly when the supply is floating?


texts: Why do some MOSFETs have a resistor in series with the gate, and others have a resistor from gate to ground?

texts: I have seen many people connecting the mosfet in two configurations the first is when the resistor is in series with the gate and the second is when the resistor is in parallel with the gate which circuit is best when the input into the gate is a logic 1 (5V) or logic 0 (0V)?


texts: Where to ground low pass filter before dual supply operated op-amp?

texts: The circuit below shows my setup. The resistor and capacitor act as passive low pass filter. In my setup the C1 is grounded to GND (0 V) but the op-amp operated with dual supply (+-5V). My question is this, do I need to ground the C1 to -5V for negative voltage inputs to make the filter work well with negative voltages?


texts:
I need to control the force exerted by an electromagnet using an MCU. it's not a commercial item so I don't have any datasheet.
Here what I know:

resistance: 8,9 ohm
may be powered up to 60V (with current limiting)

The most straightforward idea is to use a PWM and a common DC motor driver, like the DRV8844 that provides 2.5A, 60 V and decay-control.
In the datasheet pag. 13, there is an application example of driving a solenoid. And in the previous paragraph (8.1) it talks about paralleling outputs, but it doesn't mention the solenoid control (only full or half bridge).
Questions:

Why the unidirectional DC motor is connected to +V while the solenoid to GND? Shouldn't be the same stuff?

I don't understand how to paralleling outputs if using the solenoid configuration

how to limit current? I see the datasheet suggests the use of sense resistors, but I cannot find information about how they are used by the IC. Usually there is a simple equation so the internal circuit measure the peak voltage across the sense resistors to turn off the gates.


texts:
My project includes an ESP8266 (runs at 3.3v) and a USB C-Serial breakout.  The USB module can optionally run at either 5v or 3v, and there's are solderable jumper pads to make that switch.

Here's where it gets tricky.  While the ESP8266 requires 3v, I also have a separate battery charging module that requires 5v in to charge.  So I have two obvious options:

Set the USB to 5v mode.  That requires the power to the ESP8266 use a voltage regulator, and it needs a logic level converter for the serial connection.  That's two extra discrete components that can cost about $5
Keep the USB at 3v mode.  The ESP8266 will have no trouble talking to the USB module, but I'll need a 5v step-up converter to charge the battery, which will also cost about $5.

However, a third less orthodox idea comes to mind.  Is there a way to "steal" 5v from the USB module (even while it's in 3v mode) by soldering a wire to the jumper pad in the middle?  Maybe it would also require a resistor so it doesn't drain all of the power?  Ideas on any of these 3 possible solutions are welcome, I'm entirely new to prototyping electronics.

Edit: I did it! Here's a picture of the final product:


texts:
Last year I ordered this lamp, which I received a few weeks later in a rather shadily packaged box sent directly from China. The box had 110V written all over it. I still like the lamp, but we are moving overseas to Europe and I'm a bit concerned that the lamp wouldn't work or worse, cause damage once installed over there. Their customer support is not responsive, unfortunately.

The label inside shows 110-220V, which indicates I should be fine.

Is there anything I should be concerned about? What's the worst that can happen if I chose to install it in a 220V fixture?


texts: What's the difference between 1kb(64x16) and 1kb(128x8) for EEPROM memory size?

texts:
In addition to the question in the title, I have the following subquestions:

I'm guessing 64x16 means something like 64 cells of 16 bytes each. Is this accurate?
What is the significance (if any) of the memory being 64x16 vs 128x8?
What is the specific term (if any) for this (i.e. 1kb being composed of 64x16)?

The questions are made with reference to this:
EEPROM IC memory size comparison
From https://www.digikey.sg/short/pb7488


texts: 12v 400 amp cable size for winch or two cables instead of one

texts: I need to run cable to my 12v recovery winch.  Run is 15 ft from battery.    Winch info says at full load it pulls 400 amps.  Instead of running one positive lead due to the size it would need to be i need advice on size of two copper cables to run side by side.  I would have the lugs crimped and soldered .  I would like to use class m 34 awg welding cable due to flexibility. What size cable do i need for this double run and how best to run the ground and size of ground on vehicle.  I was wanting to use either two runs fo positive and two for negative of 1/0 or 2/0 instead of one run each of 4/0 since 4/0 is 7/8” diameter.


texts: Sparking and electrical arcs in electrical contact

texts:
Consider a group of 5 batteries joined up to two pieces of finely engineered metal, that form common positive and negative bridging contactors for the group.

If one of the batteries were to become disconnected for 10ms from it's contact while outputting 25W, because of a knock, would an arc form at the disconnected battery end, even though the electrons can still flow towards the other contacts at that time?


texts:
I need to implement SPI Slave (@10Mhz clock) on a microcontroller (a sensor with Cortex M33 core) in software. The problem is software is not fast enough to prepare data just after the command. (also discussed here: how-to-code-spi-slaves)
Edit: I have SPI drivers with SPI-Slave mode. So, communication is Ok. The question is about protocol.
Luckily, I also code the master (Cortex-M0+), so I am free to define the protocol. What are the options I have? Some ideas I have so far:

Option 1, Send response with a fixed delay
MOSI: command 0xFF  0xFF  0xFF  0xFF  0xFF  ...
MISO: 0xFF    dummy dummy dummy data0 data1 ...
So, master clocks for command length + response length + fixed delay. I guess it would be hard to count number of dummy bytes sent while processing and then copy data just before correct position.

Option 2, Send response with a variable delay
Similar to Option 1 but not fixed. Add a token as first byte to show where it starts.
MOSI: command 0xFF  0xFF  0xFF  0xFF  0xFF  ...
MISO: 0xFF    dummy dummy token data0 data1 ...
Problem is master should clock for command length + response length + max delay. This will slow-down communication depending on max delay.

Option 3, Request and response after interrupt
Essentially, half duplex. Just send command first and end communication. Wait for interrupt, then start communication again.
MOSI: command [wait for interrupt] 0xFF  0xFF  0xFF  ...
MISO: 0xFF    [process           ] data0 data1 data2 ...
Master needs to handle timeout and it should keep track of what was sent. I guess this is the most reasonable option.


texts: How do I safely discharge this capacitor with broken wire?

texts:
My electric lawn mower won't start, upon inspection some wires got loose and damaged by the motor.

It's a 20µF 500V capacitor. Normally I would try to short the pins with a screwdriver, but as you can see one of the pins is not connected anymore.

I don't have a power resistor. Can I try to put the leads of a light bulb socket with an incandescent light bulb to the connector + wire?

I'm used to dealing with low voltages, but I'm a bit hesitant to "mess" with a (probably still charged) high voltage capacitor.

After discharging, can I just strip the wire, heatshrink & solder the wire to fix it?


texts: Can you only lower the breakdown threshold voltage of solid insulators once with high-voltage?

texts:
For example, insulator Z has a threshold voltage of 1000V. After exposing insulator Z to more than 1000V, its breakdown threshold voltage is now 800V. Can I lower the threshold voltage further with high-voltage or can I only lower the breakdown threshold voltage once?

Here's a quote from the source material I'm reading that has me asking this question.

  Many solid insulating materials exhibit similar resistance properties:
  extremely high resistance to electron flow below some critical
  threshold voltage, then a much lower resistance at voltages beyond
  that threshold. Once a solid insulating material has been compromised
  by high-voltage breakdown, as it is called, it often does not return
  to its former insulating state, unlike most gases. It may insulate
  once again at low voltages, but its breakdown threshold voltage will
  have been decreased to some lower level, which may allow breakdown to
  occur more easily in the future. This is a common mode of failure in
  high-voltage wiring: insulation damage due to breakdown. Such failures
  may be detected through the use of special resistance meters employing
  high voltage (1000 volts or more).

I'm mainly interested in the possibility of lowering the voltage threshold further by repeated high-voltage breakdowns as described above. I understand that different insulating materials have different properties, however I don't know enough to be anymore specific. Maybe you can provide me with an example if that would help?


texts: Flash ADC's nonlinear output and response

texts:
I don't understand this paragraph about flash ADC.

A flash converter can produce a non-linear output which is an additional advantage. The voltage divider network consists of equal-value resistors which provide a proportional response. But for special applications, the value of the resistors can be changed which will give a non linear response.

How type is non-linear output? What is the meaning of first sentence?
What kind of relationship is value of the resistor's change and nonlinear response?
Please, give the example.


texts: It is better to avoid acute angle to join two routes (depending on current direction and waveform). I often see on board acute angle with a pad or a via. Is it bad? Should it be avoided as well?


texts: Why can we drop the Omega term in Euler's expression of AC signal?

texts: I know that for an AC signal like $$V=V_p\cos(\omega t+ \phi)$$ we can simplify it to $$Re(V_p e^{j(\omega t+\phi)})$$ But why can we further simplify it by dropping the Omega term  $$Re(V_p e^{j\phi})$$?


texts:
I am driving a 24V DC Motor which can draw up to 30A and I would like to incorporate some over current/short circuit protection. As such I am planning to place a shunt resistor and power MOSFET(IRF1405) after my load to switch it off if excessive current across the shunt is detected. This is illustrated in the figure below.

Where I am stuck is what circuitry can be used in place of the block labeled "Some IC?". Ideally I would like to use a single chip solution however I am unable to find something suitable. What is a good solution I can use, and what effect would such a configuration have on inrush current?

Some things i have found are the INA300 however this output signal was never designed to drive the gate of a MOSFET or the LTC4361 which is ideal but not suited for a 24V application.


texts: Bias voltage of non-inverting op amplifier drops to 0 when input signal connected

texts:
I am working on a non-inverting opamp amplifier, using OPA2134, to amplify the 150mV peak signal (1 kHz sine wave playbacked) from a phone audio jack to ~4V peak sine wave, that drives a LED using a N-channel MOSFET. My goal is to turn on the LED by playing music from the phone.

I have biased the non-inverting input of the opamp to 2.5V using a simple voltage divider from 5V. I want the opamp to work with a single supply (+5V).

List of signals:

OPA2134 V+ - +5V
OPA2134 V- - 0V (GND)
Input   Vin- 150mV peak, 1kHz
sine wave.
Desired output - ~4V peak, 1kHz sine wave.
Bias voltage - 2.5V

The input is ac-coupled, gain is set to unity at dc, and the output is also ac-coupled. I am currently not concerned with the noise from bias divider.

If the input is not connected to the phone audio jack, the inpt is floating, and the non-inverting input of the opamp is at 2.5V, the output of the opamp is also at 2.5V and the output after the output capacitor is 0V.

If however i connect the input to the audio jack the bias voltage at the non-inverting input drops to 0V. If then i play audio from the phone, the noninverting input has a signal of 1kHz 150mV peak wave instead of 2.35V to 2.65V and there is nothing at the output, since the opamp can not work with an input signal so close to it's rail.

Here is my circuit, that simulated in falstad operates as desired. For simplicity I marked the opamp max voltage to 5V and min voltage to 0V in falstad. I know that in real life, the OPA2134 can not operate rail-to-rail.
The signal on the left is the input (-150mV to 150mV), signal on the right is the output (0V - 5V)


texts: How to control high output voltage boost converter

texts:
Input 24 V, output > 100 V.

I have looked at switching controller ICs on Mouser.com but for my input voltage they are designed only to output 50 V. Like this TI TL5001


texts: Program STM32 MCU with SWD by default as alternate function

texts:
I want to use my first STM32 MCU in the project. The project involves a few peripherals (UART/SPI/I2C) and has a bit of math to do here and there, mainly bit shifting and/or integer computations, so I found myself an MCU with the peripherals I need, internal oscillator, enough flash program space and RAM for my application.
So I found this smol boi: STM32L051K8T6 in LQFP-32, Datasheet
I looked through the datasheet, everything seems clear, I have no problem picking up new stuff, IDE and all, however, I have a pair of questions I wasn't able to google up clear answer for, and the community can be more helpful anyway:

I would like to be able to program it via SWD. It's a 2 wire communication, right? SWDIO and SWCLK. So, in theory, provided I supply power for the MCU, I only need 2 pins to hook myself up to MCU (or maybe also reset? Grounds connected, obviously). I mean, I don't need large 10-pin connector or anything? Pretty much like Atmegas via UART (which need RX, TX and DTR pulse to MCU reset). Googling ST-Link v2 pinout showed me only these two and an unknown to me "SWIM" pin. (which is never mentioned in datasheet; I actually have an ST-Link v2 and even a nucleo board with on board programmer, but, again, it never hurts to ask smart people).

SWDIO and SWCLK are marked as "Alternate functions" of the pins. So, I assume, I won't be able to program it via SWDIO/SWCLK out of the box, because the pins are not configured as SWDIO/SWCLK by default. Is it something I need to use BOOT0 for? Does the bootloader from the internal memory activate SWD pins for me to program the flash? There is also no BOOT1 pin in this specific case (Ctrl+F "Boot1" yields no useful mentions in the entire datasheet).

I want to have user-updatable software. Via USB. It's easy to do it with ATMega, I just tossed in a USB-UART CP2102N, and it works like a charm, can update software all day. I guess I could write my own UART bootloader for STM32, it's only a matter of determination and taking pills to stay sane in the process. But if there is an easier way, I don't want to reinvent the wheel (although that programming part on the nucleo looks a lot bigger than just CP2102N chip).
Found this document on using UART: STM32 Bootloader UART seems promising, it doesn't seem too difficult to use CP2102N to program STM32, I guess?

Of course I have watched a few videos on the youtube about STM32 as well, but they are basically "blinky-blinky" with nucleo, not with standalone device, so not much talk about datasheets, alternate functions, controlling stuff via registers; and setting up I2C or SPI won't be a problem anyway. Basically, I have no problem controlling the registers and stuff, I just need to get it running first. It's like I can drive a car, but I don't have a key to start the engine - or maybe I do and I'm just not aware of it. In order not to explode the car on ignition, I prefer to ask questions first.
Thank you


texts:
I have a newbie-question.

I have a design for a circuit, but before I design and order PCB and assemble it I'd like to double-check whether or not some assumptions are correct.

The circuit uses 3 signals to control some ICs; since most of them are to receive the same signal I simply wired those signals from the source to all ICs that need it. In this case the same 3-pin control signals are given to 8 ICs. Can this cause problems? Simply distributing the signal like that? If so, does it scale for more than this small example? If not, what would be the best way to distribute such a control signal among ICs?

Another question I have is that ICs designed to be bidirectional, can they be used in both directions on a circuit, if switched between these directions, in a live circuit, or should such ICs stay in one direction once in a circuit? Example; read in the values of a mux and then write to the same mux/demux.


texts: Why do batteries have a short lifetime despite having no moving parts?

texts:
Chemical batteries do not seem to have any moving parts, but seem to have a rather short lifetime anyway. Why is this? The only reason I can think of is electrolyte leaking, but I have never noticed a leak of my Li-Ion phone battery and yet I have to replace it at least once a year.

Note, I'm measuring lifetime primarily in cycles of charge/discharge. There are other factors such as temperature and load (or lack thereof for long periods of time).

I'm not only interested in the Li-Ion chemistry. From what I've read, all batteries have a lifetime of charge/discharge cycles, after which they are just no good anymore.

This is apparently one of those rare things that somehow "wears out" quickly despite having no moving parts. The only other thing I know of like that is Flash memory, which wears out because the high voltage needed to write cells degrades them somehow


texts: Solution to prevent load from drawing the current from battery while it is charging and draw it from charger instead

texts:
I have the following problem: I have a 12.8V LiFePO4 Battery that powers the circuit and a lead acid charger with Intelligent MCU Control of 12V and 1.5 A to charge the battery.
When the battery is charging, the load is taking current partly from the battery and partly from the charger, putting the battery in a state of constantly discharging and charging. If I understand correctly this is not good for the battery as it lowers the capacity in the long term.
When I connect the load directly to the charger it provides enough current.
The goal is to prevent the load from taking current from the battery while the battery is charging.
I created this circuit as a possible solution and would like to know if it could work, or is there a better way, maybe an existing component, a BMS, or other solution?
I also found this BMS (VE.BUS BMS 8-70 V) but dont know if it serves the purpose, or/and is an overkill.
Any help is very much appreciated.


texts: If I need to attach a heat sink to a planar MOSFET, to which terminal should I attach it to?

texts:
This is a newbie question on MOSFET structure. If I need a heat sink to be attached to MOSFET, it should be closer to the source of heat. Here channel is the source of heat. Hence heat sink should be either to drain or source.

The bulk area of the body (substrate) has nothing to do with heat dissipation.
Is it correct?

My confusion arises because we say collector is made larger for better heat dissipation in BJT and in Power MOSFET  drain is made larger for better thermal management.

Pic Ref


texts: GPS coordinates display at UART in Degree minutes seconds format

texts:
I am receiving coordinates from my GPS module like mentioned on below.

uint8_t *latPtr = tmpPtr + 1;

when I am writing latPtr value in UART I can view lat value in terminal.

uartwrite(latPtr); // output is 1257.4370N

Find my uartwrite function on below

void uartwrite( char *data)
{
  while(*data)
  {
    EUSART_Write(*data);
    *data++;
  }
}

Now I want to convert the  lat value in to degree minutes seconds format.
So that I have written below mentioned code on my main file

float res1=*lonPtr;

float flo=res1/100;
int ilong=flo;

float lati=flo-ilong;
float res1=lati*60;
int minutes=res1;
uartwrite(minutes);

float isec=res1-minutes;
int lasec=isec*60;
uartwrite(lasec);
uartwrite("\n\r");

how to send DMS to UART?


texts: Is it Possible to Static Test With a Barbecue Lighter?

texts:
I'm working on an issue with a product where it freezes due to static shocks.

I'm trying to recreate the issue and harden the product, but I don't have a real static testing wand like the test labs use.

As a substitute, I took a barbecue lighter and connected the barrel to ground, and cut the shroud off the end so the inner spark contact is exposed. This recreates the issue reliably, but I suspect the spark is actually too powerful, such that it may be basically impossible to protect against.

I would like to do 2 things and I'm not sure how to proceed:

Attenuate the spark, using some kind of impedance network such as a resistor divider.
Measure the voltage or current pulse using an oscilloscope. I don't have any exotic probes, so I would like to build another attenuator for this purpose.

Using a device other than a barbecue lighter is also an option if it will work better. I just can't buy any multi-thousand dollar equipment for this.


texts: Why does current flow in circuit when dc voltage is applied to inductor?

texts:
I read in my textbook that when dc voltage source like a battery is connected to inductor,it develops an emf which opposes the increase of current in the circuit.On applying kirchoff's law in the loop,I can say that the back emf developed in inductor is equal to voltage of the battery ,since there is no other element in circuit where voltage drop can take place.

But then why does the current flow because there is no potential difference as the cell and inductor both have their positive plates connected to each other and have equal emf?Isn't this scenario equivalent to two cells having equal emf connected  to each other in such a way that positive terminals of both cells are connected together?


texts: Why I can not copy a content of register to another one in “always” block in Verilog?

texts:
well, I have this code, that is working perfectly:
module syncRX(clk, signal, detect);
    input clk, signal;
    output reg [7:0] detect = 0;
    reg [7:0] delay = 0;

    //wire clk_1khz;
    freq_div div(.clk(clk), .clk_1khz(clk_1khz));

    always @(posedge signal)
     begin
        detect <= detect + 1;
        delay <= 0;
     end

    always @(posedge clk_1khz)
     begin
        delay <= delay + 1;
     end

endmodule // top

module freq_div(input clk, output reg clk_1khz);
    reg [12:0] count = 0;
    always @(posedge clk)
     begin
        if(count == 6000)
            begin
                clk_1khz <= ~clk_1khz;
                count <= 0;
            end
        else
            count <= count + 1;
     end

endmodule

The problem appears when I change the line "detect <= detect + 1;" to "detect <= delay;". The intention is calculate the period of the signal, but I get this warning message of Icestorm: Warning: No clocks found in design
And the FPGA stop working... Please, anyone have an idea what is going bad? Thanks to all!


texts:
I am wanting to connect 2 boards together with a cable.  I want the connectors on the boards to be surface mount and have clips to hold the cable onto it.  I need about 8 - 10 pins.  I don't want to have to crimp wires or solder them, I would prefer something like a ribbon cable.

I have been searching all morning and cannot find anything really to fit the bill.  I checked at mouser and digikey.  I really don't know what all the keywords mean e.g.

Interconnects
  • Attenuators (146)
  • Audio / Video Connectors (5,867)
  • Automotive Connector Accessories (410)
  • Automotive Connectors (5,458)
  • Circular Connectors (66,507)
  • D-Subminiature Connectors (20,969)
  • DC Power Connectors (597)
  • Fiber Optic Connectors (2,042)
  • I/O Connectors (4,135)
  • IC & Component Sockets (9,755)
  • Lighting Connectors (320)
  • Memory Card Connectors (1,610)
  • Photovoltaic (Solar) Connectors (139)
  • Power Entry Modules (2,273)
  • Power Line Filters (3,257)
  • Rectangular Connectors (146,383)
  • RF Connectors (8,466)
  • Telecom & Ethernet Connectors (6,423)
  • Terminal Blocks (46,818)
  • Terminals (12,834)
  • Test Connectors, Probes & Testleads (2,002)
  • Test Points (124)
  • Unspecified Connectors (84)
  • USB & Firewire Connectors (1,130)

Some of them I can figure out.  Any help would be appreciated.  I can find really anything but cables.

Thanks in advance.


texts: How many 6-input LUTs are necessary to synthesize any 10-variable switching function?

texts:
For example when we need an 8 variable function with 6 input LUT we require 5 LUTs ,

And hence it seems to me that for 10 variables we would need 3 (as 2 would give cumulative of 6 variables , and the other 4 would be considered independently.BUT the answer is 21. Plz explain!!

This is what i am thinking currently.


texts: does anyone know how to simulate a solar cell with a load like an LED or a lamp or a motor or something-not just a load in the form of resistance-on Proteus?I want it work the way a normal photo-voltaic cell works ie:when light hits it, it converts the light to electric current without any external power source.How can I do this?


texts: Advantages of DDS over arbitray function generator

texts: DDS and arbitrary function generator are digital function generator, and both of them are generate sample from memory, so how to differentiate DDS and arbitrary function generator in term of the operation? and waht is the advantages of DDS over arbitrary as DDS quite popular right now.


texts: Must an LCD panel meet specific requirements to support a higher refresh rate?

texts: Newer LCDs can refresh the screen at 120Hz or higher. The driver circuitry for the panel is responsible for pushing frames to the panel at a given rate, but are there any particulars of the LCD panel itself that factor into achieving the higher refresh rate? Are there, for instance, any special materials, construction, or circuitry of the panel needed to correctly respond to a higher refresh rate? In other words, is it theoretically possible to drive a panel over its specified refresh rate using another driver board, assuming all interfacing requirements are identical?


texts: I have a 110 VAC solenoid and want to know what kind of circuit i should build to control it from my microcontroller?

texts: My solenoid is part of an old espresso machine, the circuit that detected low water level died and i can't replace it. I am adding a micro-controller to remotely turn it on and off and to control this water fill solenoid. I have the water detection taken care of, I built a control circuit that i can use to control a 12 V relay. My idea is to have the relay turn the solenoid on and off (the old circuit use a relay too). but I am just getting back into electronics and don't want damage the solenoid as a replacement would be very hard to obtain. Can anyone help me on what i should to to safely control this solenoid and protect both my micro-controller and the solenoid?


texts:
I haven't seen any restrictions about minimum clock, but I may have overlooked them.

EDIT:
The module is a Crucial CT4G4SFS824A, based (this is an informed guess) on  4Gb Micron 512 Meg x 8


texts:
Hello electrical community ! I'm learning about FM Modulation ,especially with  narrow Band FM.And I was wondering if the index of modulation BETA affect the bandwidth of the modulated signal.
In fact , I tried simulation with MATLAB , but I didn't notice change in the bandwidth.
The formula I used is the Carson one:
$$B = 2(\beta +1)f_{m}$$
But I saw that in NBFM the bandwidth was defined like this :
$$B = 2f_{m}$$
Which one should I use ? by choosing the correct one , I think that I will be able to answer my problem which is : '''Does the bandwidth of an  NBFM modulation change depending with the modulation index?'''


texts: How does a pull-down prevent a "false 1" in a pin?

texts:
yesterday I asked a question about pull-ups and pull-downs and resistance in an input pin, but I feel that the question that invaded me today is different from my yesterday's post so this is why I'm asking a new question instead of just editing yesterday's question.
Maybe my question is similar to other questions in this site (like this: Why does a pull down resistor eliminate floating input , but I feel that they are not exactly answering what I want to know.
Let's start with the question, we have this:

I understand that, if the pull-down didn't exist, we would have a floating input in our microcontroller pin, because some interferences could give a logic '1' to our microcontroller. But what I don't understand is how the pull-down does to always get a logical 0 on that pin (when the button is not pressed).
I mean: supose that interferences are giving 4V (logical 1), for example because we touch it with the finger. Here:

So what I imagine that is happening is this:

This is why I'm not able to understand why pull-down is avoiding a voltage on the microcontroller pin due to interference.
I want to add this question too because I don't understand very well this concept:
Why is it considered to be a weak 0 in a pull-down and not a strong 0?


texts: Modulating a (diaphragm/direct lift) solenoid valve for proportional output

texts:
I am attempting to build a water control system which allows proportional control of the water output flow.

I had initially thought of using servo-controlled ball valves, but it was suggested that solenoid valves can be modulated using PWM or similar input and thus end up with a somewhat variable flow rate.

However, I just tested a diaphragm/direct lift solenoid valve (like this one from ebay) using different input frequencies and duty cycles, and was unable to achieve anything other than a "full on" and "full off" condition.

Must I use a "direct acting" solenoid instead, in which the solenoid plunger directly controls the flow?

or does someone know if it's possible to modulate the diaphragm-type valves?  If so, what frequencies and duty cycles would be most effective?

Valve requirements

Standard (US) municipal water source (50-100psi)
3/8" to 1/2" water supply line
12VDC (or less) input voltage, with minimal current draw (1A or less)
Normally closed
Low heat output - can stay open for extended periods (hours)
very inexpensive - less than $10 each (preferably less than $5/ea)

Thanks for any insight!
(Would this be a better question for the Engineering section?)


texts: How can I protect an input signal to unpowered CMOS?

texts:
My circuit has a battery charger and an ATMega88. The ATMega needs to sense the state of the battery charger - but if the battery is too low, the ATMega may not have power.

I know it's bad to drive a CMOS input more than 0.3V above VCC - you can power chips through the protection diodes, cause latch-up, etc.

I see three possible solutions:

1) Use a dual-supply bus transciever. http://www.ti.com/lit/ds/symlink/sn74lvc1t45.pdf This adds more cost than I'd like.

2) Put a 100K resistor inline with the signal, so that "not much" current flows into the powered-off circuit. I think this shouldn't cause latch-up or burn anything out, but could still power-up some circuitry and cause undesired operation.

3) Use divider resistors to step the signal down to <0.3V, and feed it into an ADC pin. This requires extra work and time to sense - and I'm still just a bit nervous about feeding any voltage/current into unpowered CMOS.

So I'm inclined to go with option 3, but hoping there's a better option I haven't thought of.


texts: Anyone knows what is a driver implementation in Harmony?

texts:
When configuring a Timer Driver implementation the option for Dynamic and Static appears.

Anyone knows, what does these 2 types mean?


texts: What effect does using a termination resistor that is larger than the characteristic impedance of the transmission line?

texts: I have seen that when terminating an RS422 point-to-point connection, you should terminate the signals with a parallel resistor that matches the characteristic impedance of the transmission line. Most sources recommend 100-120ohms. I saw another post here that mentioned the effects of using too small of a terminating resistor, but what happens if you use a terminating resistor that is double, or 10 times the value of the characteristic impedance of the line?


texts: is it okay 4 years old used UPS Battery filling sulfuric Acid insted of Distilled water?

texts:
I've 1250VA UPS where I found 2 battery (12V-9AH). which Is used for 4 and years more.
When I brought this UPS it gave almost 80 to 90 minutes backup but now it only lasts for 15 min.
so I decided to replace the battery, but when I opened up the caps both the batteries are dry (no liquid on it). still, it has 13.5V after full charge. Is it a good idea to refill the sulfuric Acid instead of distill water?
and what if I replace UPS battery to Car Battery 12V 35AH?


texts: PIC : EEPROM not write properly to 0xFF in PIC18F67K22 controller

texts:
I am writing values from 0x50 to 0x3ff in EEPROM of pic18f67k22. Whenever eeprom is getting full, I am writing 0xFF and then after write my data from 0x50 location.
but some time eeprom is not write properly to 0xFF to all location.
I am using simple FOR loop to write 0xFF.

 for(i=0; i<900; i++)
 {
     Write_b_eep(0x50+i,0xFF);  //This stores the no of session by incrementing it by one
     Busy_eep();
 }

What I am missing?


texts: Can I just use one end of a differential op-amp ? (ie use differential op-amp as a single ended op-amp)

texts:
I found this awesome op-amp I can use which is super cheap and super fast (NE592D).

Unfortunately, it has  differential inputs and outputs. I can probably deal with the differential inputs, but how can I convert the differential output into a single ended output?

Can I just put one end to ground? or to ground via a DC blocking cap? or even just not connect one side?


texts: White noise generator for audio jamming ( from 250 Hz to 4.5 KHz )

texts:
I want to implement a white noise generator device for the purpose of audio
recording jamming ,
as I can make the recorder record the noise and the speech together
so any one try to record the speech , he/she will hear a noisy speech ,
But from where I should begin ?

Thanks


texts: Do I need an UL approval if I build a machine and use it in my own company?

texts:
Do I need an UL approval (or any test lab) if I build a machine and use it in my own company?

Where can I find a legit documentation on this subject.


texts: How to tell the difference between heat shrink tape and normal wire tape?

texts:
Heat shrink tape

Wire tape

They look exactly the same, especially with the absence of any markings on the ring...  How can I tell the difference between the two?


texts: Will reed switches break in various weather conditions

texts:
I will be using an OKI ORD-9216 14mm reed switch in my mailbox, which is outside of my house.
Below is a picture of a reed switch.

I am worried to whether the reed switch's glass will crack due to changes in temperature, humidity, and air pressure?
Since the reed switch will be inside the mailbox, does it matter if I have an enclosure for it?
Have you guys seen any device that contains a reed switch that is used in harsh weather conditions?


texts: Using shielded audio cable for potentiometer sensor

texts:
I'm trying to measure a potentiometer from an Arduino's ADC. The potentiometer has a maximum value of 100k ohms and is located about 1 meter from the Arduino. The potentiometer's wiper is wired to the ADC pin and the pin to ground. I've enabled the 20k internal pullup on the ADC pin, so the potentiometer creates a logical high and low at the extremes. I have the potentiometer wired using two stranded 24 awg unshielded wires, twisted together.

To filter out noise, I'm using an exponential moving average on the Arduino. However, even with this, I'm still seeing a +/- 10 unit change several times a second, even when the potentiometer is completely still.

The two ways I've read about reducing noise in wires carrying analog signals are:

Using a shielded cable

Would it make any difference if I instead used a two-conductor shielded audio cable? I have one audio cable that has a red and black wire, as well as metal shielding. If I attach my potentiometer's pin to the two wires, should I also wire the shielding to the ground or leave it unattached?

I see a lot of conflicting opinions over how to leave the shielding, with commenters in this thread suggesting to leave it ungrounded, or grounded at the sensor end, or grounded at the Arduino end, but definitely not grounded at both ends. Which is best for my case?

Using a capacitor

How much of a difference would it make if I placed a 0.1uF capacitor across the wires, as a low pass filter? Should I place it on the sensor side or the Arduino side? Again, I've seen a lot of conflicting advice about this.