texts: Calculating gain of simple op-amp using KCL

texts:
I'm having a bit of trouble calculating the expression for the gain \$ V_{\text{out}}/V_{\text{in}}\$ for the given Op-Amp circuit down below. I've gotten to the point where I've written out the KCL equations for this circuit.
What I have so far is, that the output current from the Op-Amp,\$i_0\$, splits up into \$i_1, i_2, i_3\$, which go through \$R_2\$, \$V_o\$, and \$R_3\$ respectively.
We can clearly see \$i_0 = i_1 + i_2 + i_3\$.
As far as fleshing out the KCL equations, I've calculated \$i_3\$, going through \$ R_3 \$ which I've derived as $$i_3 = \frac{V_{\text{GND}} - V_0}{R_3} = \frac{V_0}{R_3}$$ and similarly we can reduce $$i_0 = i_1 + i_2 + i_3 \rightarrow i_0 = i_2 + i_3$$
This is since \$i_1 = i_n\$ which is the current into the negative node of the op amp, which we know that current going into either node, \$i_n\$ or \$i_p\$ must be zero.
At this point, I'm stuck producing the necessary equations for \$i_2\$ (that is dependent of the voltages \$V_0\$ or \$V_{\text{in}}\$ which we know), out into the rest of the general circuitry. Any and all help getting these equations in order would be greatly appreciated!

simulate this circuit – Schematic created using CircuitLab


texts: How do I combine 3 batteries in series and parallel with different outputs?

texts:
I'm looking to combine the 2 circuits shown in the picture below using a switch.(ON-OFF-ON)
I would like to keep the 12V output seperate from the 24V output.
This is to maximize efficiency when using 12V with the added possibility of using 24V and 12V at the same time.

Switching 2 batteries from series to parallel with one output using a DPDT switch seems logical to me, but combining 3 batteries in the desired way is a bit overwhelming because in my attempts there's always a short.

edit: my problem: I have 3 battery mounts on a camera system with interchangeable batteries (sometimes I only use 2 batteries, sometimes 3 because weight distribution is important, all are charged seperately). I need a 12V out all the time and sometimes 24V. I would like to discharge all batteries as evenly as possible.


texts: When is a FPGA preferred instead of a CPLD, and vice versa?

texts:
I am starting out with programmable logic, and I am mostly using schematic entry. (Hey, I like to see the schematic instead of VHDL/VERILOG :P)

I have been using a Xilinx CPLD originally that had 128 macrocells, and the design has a data bus and used tri state buffers extensively. Turns out it did not fit into the CPLD, and the next step on digikey was a Xilinx FPGA ($5.80), so I figured all I would have to do was change the device to the FPGA in the ISE. Apparently the Tri state buffers do not exist on an FPGA which means I have to redesign a great deal. Also, one of the main reasons I wanted to use a FPGA was because the FPGA can be programmed using a SPI flash instead of JTAG. (I don't have any JTAG programmers, but I have MCU's to program SPI flash) There is the MachXO2 on digikey for similar price but with 640 macrocells, which I figure should be more than enough, not to mention that it can be programmed using SPI flash, and probably has the Tri state buffers.

So, here is the question. When are CPLD's used instead of FPGA's and vice versa. In what applications does a CPLD not make sense, but a FPGA is better suited for?


texts: Analytically understanding wireless power transfer

texts:
https://youtu.be/M8aZoM9p43k
This YouTube link shows a experiment I quickly made.  Two resonant lc circuits that use magnetic fields to wirelessly light up a led. I manually found the best frequency after finding the inductance using a LCR meter. Its low frequency, so like 200kHz. No impedance matching. My two main questions are: Is there a way to analytically solve for the power received. I know inductance, frequency, coil size, wire size, etc. Also, can you calculate for power received when a foreign similar coil is placed wirelessly in between the sending and receiving coil. If you watch the link, you see it increases power transfer. It can also decrease the power transfer. Im guessing because it changes inductance and throws off resonance. Is there a general equation for power transfer as a function of distance, inductive loops, frequency, etc.
Also, from my experiment, a square wave works much better than a sin wave and the signal received in the oscilloscope is sin wave, even though im sending a square wave. Is there math to explain the square wave working better(found experimentally) and the signal received is a sinusoid?
Thank you


texts: Are the "universal" laptop chargers safe / how do they work?

texts:
I recently got a "Boltpower Car Jump Starter, Rocket Socket" that had an interesting feature, it had some odd looking adapters for laptops (none helpful for me unfortunately), that are supposed to charge a laptop battery.

The odd thing about this adapter is that it has a button that easily toggles 12v, 16v, 19v, off... as I understand, laptops need input power at the specified voltage and minimum amperage (in my case 19.5v 4.6a). I have to wonder if this is actually safe as laptop power... and if I found an extra plug and wired it to it, would it be safe to plug in?

The description on Amazon says "over current protection, short circuit protection, overload protection, over-voltage protection" and I'm curious what method they use for this - is it easy to implement if I were to build a custom charging adapter or kinetic generator of some sort - or is this expected to be protected on the laptop battery, similar to the overcharge protection that's part of every device with a li-ion?


texts: Is it possible for any circuit to independently make its own trigger, sweep or oscillation without the aid of an AC sine wave?

texts: Even a Schmidt trigger, attributed to being able to create the start of an oscillating circuit, has to get its start from an AC sine wave. It seems that no amount of tubes or transistors can independently make their own trigger. This mechanism for quick switching has to come from someplace, and without anybody being able to explain it to me, the only thing I can think of that makes quick switching possible is the fact that our circuit is plugged into this wall outlet that happens to have a quick moving alternating sine wave current flowing through it. Is it possible to create an electrical circuit that only has one initiating signal (the press of a button or the presence of DC voltage, say) that can cause itself to switch based on that one signal? The only thing I can think of that can independently switch is a thermal flasher.


texts:
Is Java good-to-learn-next language for an embedded software engineer who mainly develops firmwares and drivers? If not so useful, why?

Which language is more for that purpose, C++ or Java? I read on a lot of websites, that Java is the most payed programming language nowadays, but also that C++ mixed with C is very used in embedded software development.

I want to hear from some embedded software engineers on what programming language (C++ or Java) to pay attention for purpose I wrote above?

I think that just C is not enough and want to go in right direction, and not to learn something I will not use in embedded systems.

Thanks.


texts: What is the main factor silver in solder wire?

texts:
Previously I was using traditional soldering wire 60/40 Sn/Pb (stannous)(lead). Restriction of Hazardous Substances (RoHS) says that Pb (lead) is dangerous for enviroment. So we should not use lead. When I searched a little, I saw that there was soldering in a wide variety of mixtures and I was a little confused. There is (video link) a wide variety of soldering wire examination,

Sn 99.3 Cu 0.7 the link

Sn 96,5 Ag 3 Cu 0,5 the link

2% Silver Solder Wire the link

at the video, if i don't get it wrong, He is saying solder wire with silver are better. I want to learn key factor of silver at solder wire. also some solder wire has copper, What is the benefit of 0.5 copper?

I am using solder wire for general purpose such as PCB, on circuit boards. Which mixture should I choose while soldering? I think this solder is the best Sn 96,5 Ag3 Cu 0,5


texts: Is there a way to set different sampling frequencies to channels in ADS1256?

texts:
In order to acquire 3 analog signals with a Raspberry Pi 4, I want to use Waveshare's ADS1256 AD expansion board (8 channels single-ended, 24 bit.)
I was wondering if there's a way to set a different sampling frequency to each channel.
The ADS1256's datasheet states that the maximum fs is 30kSPS. Since I need to acquire 3 signals and one of them needs to be sampled at 10kHz, I want to know if there's a way to set a specific fs to each channel.
In this way I could sample correctly the audio signal (10kHz) and not oversample the other ones. So far, I've just downloaded the source code (Python) provided by Waveshare but I don't understand if there's a way to change it to do what I want.


texts: Simple Series Circuit: depending where the resistor is, I get different results. Explanation?

texts:
I am building a very simple Series circuit with a better (9V), two LEDs (Red, 5mm) and a resistor (220Ω). See the circuit below.

Now, when I connect it all together, here is what happens:

1) (+), LED1, LED2, Resistor, (-): only LED1 lights up (that's the example on the picture)

2) (+), Resistor, LED1, LED2, (-): both LEDs light up

3) (+), LED1, Resistor, LED2, (-): both LEDs light up

So turns out, my circuit doesn't work when the resistor is connected directly to (-).

I have been told that in such simple circuit it doesn't matter where is the resistor.

Does anyone have an explanation to this?

Thank you! :)


texts:
Please help. In reverse bias we say the negative terminal of the battery attracts holes of the p-type hence depletion zone becomes bigger. Why don't electrons from the negative side of the battery actually move to go and fill the holes then repel electrons in the n-type through the wire and to the battery creating a current in reverse bias?!

Depletion zone is made by electrons from n-type going to p-type then surely electrons from the battery could travel to the holes in the p-type as well instead of just ATTRACTING the holes. Please can someone explain this it is really confusing me.


texts: Can water in conduit cause an increase in voltage?

texts: I'm a electrical & solar contractor. We installed a 38 kW system consisting of 3 inverters and (120) 320 watt panels, 40 per inverter. When we energize each inverter the voltage increases all along the system. I've got all the voltages if you need them. The inverter company had us bypass all breakers, fuses and bussing to confirm no unacceptable resisatance when systems are rpoducing power. And the utility came out and reworked all connections from transformer to meter. Inverter company suggested all this and we complied. Voltage increase still exists. When 1st system turned on voltage goes from 244 to 251. When 2nd system turned on voltage goes from 251 to 259.5. When 3rd comes on it goes from 259.5 to 267.6. Any combination of inverters on and off produce like results. Now the inverter tech support people say water in the conduit can cause this.  The wire is 4/0 AL XHHW. The most amperage recorded is 111 but mostly it runs at about 80 amps. All new wire and equipment. I'm not an engineer. Do you have any suggestions as to the cause of this? I've googled this question and also looked in advance search in this forum.


texts: Can I use rectified AC current to heat an object inside a induction coil?

texts:
The reason why I would like to use rectified AC is because I want to keep the magnetic field inside the coil unidirectional. A changing magnetic field induces current in the coil and vice versa. Although the current now flows in a single direction, its magnitude changes with time, it does not seem to me that using DC ripples would contradict Faraday's law.

Hysteresis loss (this is now gone since the magnetic dipole moment won't spin due to the unidirectional field )
Eddy current (this should still be here???....)

Thank you.

//////////Update//////////

The unidirectional magnetic field is for alignment applications, I was wondering if I could get both heating and alignment at the same time without resorting to a mechanical switch that changes the AC source to a DC source. From the answers so far, it seems it is not recommended.


texts: A device which will detect a difference in voltage

texts:
A comparator can compare two voltages and output a signal indicating whether one is greater than the other. However, for balancing a lithium-polymer battery pack, I need to measure the difference between two cells which are not relative to ground.

The simplest solution is to just use voltage dividers to drop the voltage down to about 4.2V to compare against a reference voltage. However that solution would have a poor CMRR for higher voltage battery packs, with 6 to 8 cells. It would also be highly dependent on the divider accuracy, meaning expensive precision resistors.

I'm aware I can use op-amps to produce a difference signal. However, that would then require a further comparator to accomplish what I want. For an 8-cell battery pack, we would be looking at two op-amps and two comparators which is a lot; size and power consumption are important.

Basically I'm looking for a device which does this: if((V1 - V2) >= V3) then output high else output low.


texts: Centroid of component for pick and place machine using Eagle

texts:
Just finished designing a PCB and sent the Gerbers off to my board house (Bittele) and they have requested that I also provide them with a pick and place file.

Using Eagle, I ran mountsmd.ulp and generated a pick and place file for my board.

Looking over the file and comparing its output to my board layout file, I noticed that the centroid of my FET component appears to be located off of the body of the component:

Is this a mistake?

I think this Eagle ULP takes the centroid of each pad, determines which pads are at the extremities of the component (i.e. if it was a 6-pin sot23 device it would take the four corners) and then finds the geometric mean of these pads.

In my example this ends up being off of the body of the component.

For larger components like this one, does the pick and place machine automatically make an adjustment on-the-fly so that it picks up the component by its body?


texts: I'm having trouble trying to design a Class D Amplifier. Does anyone have any tips on where I can start?

texts:
I'm aiming to design a 4 NMOS H-Bridge switching configuration.
I understand that I am going to need:

two half bridge gate drivers to driver the mosfets
a comparator stage to compare the audible and high frequency signal
low pass filter stage to filter the high frequencies.

A few design constraints of this amp includes:

5W output
42kHz switching frequency
2kHz audible signal


texts: VDD on crystal oscillator to GND or +3.3V? (ESP8266EX)

texts:
Currently I'm trying to make a circuit for the ESP8266EX Chip and I've stumbled across the "Crystal Oscillator" - section.

It's said that the ESP8266EX supports 40MHz, 26MHz and 24MHz crystal oscillators, with +-10PPM. In the schematic on page 9/30 there are 4 pins on the oscillator. XIN; XOUT; GND; GND. When I try to select an oscillator using the easyEDA software I can never find 2x GND outputs. It's always one ground and one VDD pin.

Basically I think I'm just getting confused by the labeling. What I would've done is, connect GND to GND and VDD to GND.

This is the oscillator I'm talking about in particular. When implementing him to easyEDA the pin no.4 is not GND but rather VDD.

So, what does the VDD stand for? According to my research it stands vor Voltage Drain Drain. VSS stands for Voltage Source Source and is 0V, thus VDD being different from 0V.

But how come there is an oscillator in the datasheet with 2xGND and no VDD, while I can only find them with 1xGND and 1xVDD?

Please correct me on my misunderstanding.


texts: Will does this circuit require any resistors for its 7-segment display?

texts:
The circuit I'm trying to build is attached as a logisim simulation screenshot. The source is a 5V battery. The display is a 5161AS common-cathode display.

I've seen people use resistors whenever they use LED displays.

Now, my question is: will resistors still be necessary in this circuit? Isn't the current already going through the internal resistance of the components?


texts: Schematic review: prioritized power ORing

texts:
I am in the process of designing a circuit which will allow me to safely OR two power supplies.
Constraints:

5V
up to 5A from Vin_hi_prio
up to 2A from Vin_low_prio
Both come from the same PSU but through different routes
Vin_hi_pro should be preferred if present
Voltage drop should be under 200mV
When the power is turned on, it stays on - this is not a hot swap circuit. Both voltages will be switched off at roughly the same time.

What I have considered:

Diodes - voltage drop was too high
Dedicated IC - I had trouble finding one which would look good to me and I don't want to pay 3-4$ when it seems like a BC817 will do

My questions:

Does this circuit look good? Or did I miss something that should be relatively obvious?
Will this circuit, designed in a simulation, hold up in real life with real components and their manufacturing variations? I'm particularly worried about Q1 Vbe - it seems like the circuit will be very sensitive to variations here and might allow short connections between the two voltage sources.
Since both both power inputs come from the same power supply but through different paths, do I even have to care about switching/ORing those two voltages? They might come from different rails.
Do I need to care about any extra current running through my ground?


texts:
I have design a board on Kicad and now trying to route the tracks. However there is something I don't understand. Different pins on a microcontroller are connected to 3.3V power source through a capacitor or a resistor, like on the schematic below.

simulate this circuit – Schematic created using CircuitLab

When I then place the components and try to route the tracks, Kicad proposes to connect the pins of the microcontroller to the closest component. For example, if I place C1 in front of P2 and C2 in front of P1, it will tell me to route P1 to C2 and vice versa.
It's the same with anything connected to +3.3V on my schematic.
I think it's because I use the "+3.3V" symbol of Kicad but is it acceptable ?
Or do I have to use a "dedicated" +3.3V label for each pin ?

Thanks :-)


texts: How to prove a system is stable if the characteristic equation have non zero positive coefficients?

texts: I read that a control system would be stable if its characteristic equation has got all the terms present and are positive. But I could not find any proof to it. How does one prove it?


texts: Is there a way to optimize this solution for closing two circuits with one button on a scale?

texts:
I am (as a hobby) looking into making a keypad with independently scanned keys. I am going with a row-column matrix approach (due to limited GPIO). And would like to utilize MCUs low power modes. Now to achieve both criteria I need to keep rows low unless I detect a button press, which I can do with a wakeup pin on MCU.

However, my layman knowledge of circuits only comes up with a head-on solution by using mosfets like below (it is overly simplified, but I hope delivers the point):

Now, this will be awful lot of mosfets for any reasonable number of keys (think a 104-keyboard). While sure this solution would work, I can't help but ask whether there is a better solution to this problem (preferably using only simple electrical components since 1 MCU is already enough to blow my brain).


texts: What kind of capacitors are these small, cube-shaped surface-mount components?

texts:
Complete newbie question...

I'm troubleshooting a PCB that includes 4x very small cube-shaped components, labeled C2, C3, C5, and C6 so I presume they're capacitors.  They're soldered in parallel and there's no visible markings on them, but appear to be ceramic and are approximately 1mm on all dimensions.


texts: Driving Multiple Balanced Audio Runs Off Single Differential Op-Amp Circuit

texts:
I am working on an audio project that needs to drive 16 balanced xlr cable runs with stereo differential audio. For this purpose I am using the following op-amp circuit to produce a low impedance differential output:

In this circuit R20 functions as a current limiting resistor, and effectively sets the output impedance at 75 ohms, while C32 and R24 decouple the audio signal from the DC bias.
In my application I am generating a stereo test signal and sending it to all available outputs (alternating left and right for even and odd), so I just need a way to safely buffer the output a bunch of times in such a way that the outputs can't interact with one another.
My question is whether I can safely drive multiple lines off the same op-amp by simply attaching multiples of the R20, C23, R24 current-limiting + decoupling circuit to the same op-amp outputs.  Theoretically with an ideal op-amp circuit this should work fine, since the op-amp will hold the voltage constant at it's output, and the output resistors will limit current preventing voltage drop, but I am wondering if this can lead to problems with noise, or other interaction between the output lines when put into physical practice. Furthermore, seeing as I'm planning to drive up to 16 lines, is there a way I can calculate a max channel cutoff for when I should break this method out to multiple op-amps?
This is meant to be a piece of test equipment, so having it be reliably low noise is important, but being able to have a single op-amp package rather than 16 of them would be a big reduction in cost and board space, so it's worth exploring.
Thanks!


texts: Step down 3 phase 2kV AC to 3-12V at modest current (5-20mA max)

texts:
I'm looking for a way to step down 3 phase, 2kV AC power to 3-12V DC.  I do not have a neutral, just the 3 phases and ground.  This will be entirely isolated, nobody will be anywhere near this thing.  In fact, it will placed inside a thick, grounded metal case that will be essentially tamper-proof.

The components need to be rated for a 175C environment... which really messes with the available options.

I'd also like it to be able to survive and hopefully still operate if one of the phases is shorted out or grounded.  :)  So...  kinda harsh criteria and environment.

On the plus side, the thermal sinking capability of the system is quite high.... but then I'd prefer to minimize that as much as possible.  It's there if required.

I don't need that much, somewhere between 5-20mA (probably around 10mA).

I'm currently rectifying the three phases with half-bridges, voltage dividing that (burning power in the process, but limiting voltage on the smoothing cap).  It seems to work, but I'm sure there's a better way.

I've looked a little into custom transformers, but it's not clear how much power will be wasted in those either.

EDIT This can weight a good bit (< 50 lbs, target is maybe 10-20ish).  It should fit in say a 4" x 12" cylinder, although preferably under 8" long.

Thoughts would be appreciated.


texts: Common-mode voltage outside the specified range

texts:
I'm reading the datasheet of TL331. Here a summary of the relevant specification for my question:

ABSOLUTE MAXIMUM RATINGS
VCC Supply voltage 36 V
VID Differential input voltage ±36 V
VI Input voltage range (either input) –0.3 V to 36 V

ELECTRICAL CHARACTERISTICS
VICR Common-mode input voltage 0 to VCC – 1.5 V

with this note:

  [...] The upper end of the commonmode
  voltage range is VCC+ – 1.5 V at 25ºC, but either or both inputs can go to 30 V without damage.

I'm going to use this component as a comparator (i.e. without any feedback) in this situation:

single power supply: 12V
IN-: 9V
IN+: 18V

Now, the absolute maximum ratings are satisfied and also the second clause of the note. But the common-mode voltage is 13.5V, and this is outside the specification (VCC-1.5V = 10.5V).

So, I cannot use this amplifier at all? Or, because I'm going to use it as a comparator it would work anyway? I mean, the outputs would saturate without actually be able to make V+ = V-.


texts: I am trying to use a potentiometer with a capacitive supply and microcontroller. As digital-to-analog output current is too low, a buffer is needed. Buffer output is the Vcc at potentiometer. Problem is the supply, while op-amp is connected, supply voltage is 1.2V at most. From datasheet current draw is ~1mA, so that shouldn't be a reason for such high voltage drop on supply. What causes this behaviour ?


texts: Why is actual SOC of a battery actually higher than what is displayed

texts:
So I read a document today which said that a higher SOC level (around 20%) is displayed as 0% to the user in vehicles, thus reducing the total capacity of the battery.
My question is that why is that done? Why do we limit the depth of discharge? I know for some batteries like NiMH there are memory effects, but why do we do it for other batteries like Li-ion?


texts: Basic voltage/current regulation with MOSFET, cannot fully close current controlling MOSFET

texts:
I tried to decrease value of Rg resistor on the gate of the MOSFET (the one on the right) but then the MOSFET does not open enough and i get low currents trough it, i have this setup on breadboard and results are very close to simulation, when i have voltage at 10V and current fully closed i read 15-20mA on the DMM.
I use IRF630 for MOSFETS and the circuit is powered off laptop charger 19V.
Thanks.
Edit: There is also error in regulation, preventing the mosfet to close fully as there is 3.2V at gate when the voltage is closed, i guess that is the reason it does not close.
Link to simulation: Falstad Simulation


texts: Circuit design for controlling 6 individually selectable motors

texts:
I need to control 6 of these DC motors from an Arduino. If I needed to control them entirely independently, the obvious choice would be 6 H-Bridges, but I have somewhat relaxed constraints, so I'm wondering if there's a better (more component efficient) way to do it. Here are my constraints:

I need to be able to have them run both forwards and backwards, BUT
I will always be controlling a subset of the motors, which will all be going in the same direction.
I only need to power 2 or 3 of them at one time.
Although the stall current listed is 1.6A, I don't expect to run them at more than about half that.
I don't need PWM control - full on or nothing is fine.

My initial thought was to use a single H-Bridge capable of sourcing enough current for 2 or 3 of the motors, connected to one relay or triac for each motor, which the Arduino can use to enable individual motors. I've never worked with triacs before, though, and have somewhat limited experience with circuit design in general, so I could use some advice.

What's the best design for this? I don't have any experience with surface mount soldering, so something that can be built through-hole would be ideal. If it can fit on an Arduino shield, even better.
Given a design from 1, how should I select the parts to use?


texts: I am using CS5463 for energy metering application. Is there any way to check if IC is working properly without communicating with the IC through SPI interface? I just want to make sure that the connections are right before programming the controller.


texts: How does TXS0108E keep it's outputs at high impedance given it's internal block diagram?

texts:
I am trying to understand the block diagram of the TXS0108E bidirectional logic shifter. In the chip's description it says

  When the output-enable (OE) input is low, all outputs are placed in
  the high-impedance (Hi-Z) state.

However at page 18, this block diagram is given:

There are pull ups at both the Va and Vb side pins, so if the gate at the centre is not turned on, shouldn't the Va and Vb side pins have a voltage of Va and Vb respectively?

If I understand correctly, something like this would give a high impedance output when the input level is 0

but the pull ups in the TXS0801E chip should prevent the output from going high impedance. So what does it mean when it says the chip outputs are placed in high impedance when the OE pin is set to low?


texts:
For the purposes of configuring an ATmega324A for use with an XTAL, is the TXC 9C-11.2896MAAJ-T considered to be a low power crystal oscillator or a full swing crystal oscillator?

Please see page 39 of the ATmega324A data sheet.

Thanks.


texts:
The question is that: How could you make a Wien bridge tune to different frequencies?

Since the frequency is depended on the value of the resistor and capacitor we should use a variable resistor and capacitor. But, I am not sure if this is the right approach.


texts: Can I make this Bluetooth speaker stop cutting off its speakers when audio signal goes silent?

texts:
I have a simple Bluetooth speaker that always seem to cut off its speaker circuit when the audio stream goes silent. This makes an audible popping noise, which is repeated when the stream starts delivering actual sound again. As long as there's sound playing continuously it works ok.

The problem is that the speakers are always activated too late, resulting in skipping the first syllable of a sentence in an audio book or in a video with silent parts.

Another problem is that it also happens whenever the volume is very low at the source, which means I don't get to listen to the actual audio, just a lot of popping noises.

The IC responsible for driving the speakers seems to be M6008N. My question is if it's possible to make it stop cutting off the speakers just because the stream is silent?

Details

The problem only occurs when playing from a digital source, i.e. Bluetooth and not through line in.
It only occurs when played through its built-in speakers, i.e. not using its line out port.

I could only find data sheets in chinese of the IC.

Am I even looking at the right thing?

The only other thing of interest is a tiny premade bluetooth module board which I can't do much with. It seems to take care of storing the sound effects and handling the mandatory worthless microphone, but I can't say if that raises the probability of the problem being located on it.

My level: beginner


texts: How to declare register values as an input in Verilog?

texts:
I have a data set consisting of 30 values and each of 16 bit wide. I tried to add these values as an input in my Verilog code in the following way:

`timescale 1ns / 1ps
module com (inp,clk,out);
input clk;
input reg [15:0] inp;//dataset
output out;
.
.
.

but when I am writing input reg [15:0] inp; it is showing some error.

Can anybody tell me how can I use this data set values as an input in my verilog code.


texts: What are the Pros/Cons on the 30 Degree voltage phase shift between the primary and secondary of a Delta-Wye Transformer

texts: I have searched this wonderfully informative website and learned much about Delta-Wye connections and why a phase shift in voltage would exist between the two. I am also aware that both Delta-Delta and Wye-Wye connections do not have this phase shift. My questions is: What is so important about this phase shift? Are there Pros/Cons?


texts: Inductance of Shielded Helical Resonators

texts:
I found an equation in a thesis which calculates the inductance for a helical coil inside of a cylindrical shield:

$$L = (\pi N d_{coil})^{2}\frac{1}{l_{coil} +0.45 d_{coil}}\left(1 -\frac{d_{coil}^{3}}{D_{shield}^{3}}\right)\left(1- \frac{l_{coil}^{2}}{2L_{shield}^{2}}\right)$$

It is surprisingly accurate, I'm wondering if anyone has seen this before and if they have, is there a source or a derivation where this equation is explained?


texts: How to isolate sensor power and ground lines as simply as possible

texts:
I have an Arduino project that includes three sensors a EC, PH and PPM sensor.
The problem is that when you read a sensor the other two sensors
affect the reading of the current sensor due to the power and ground lines still being active. This is because the sensors work on the water's resistance or ionization.

To combat this problem I created a simple circuit using what I had in my drawer.
Now it should be said I am no electronic engineer, I am a software developer.
So the circuit I created works but my be very wrong as far as best practice.

I used two NPN transistors for each sensor to effectively change the power and ground line to a floating state or at least very high impedance. Again the power and ground must not be pulled low or high or else it will affect the other sensors.

Examining the diagram below you can see my attempt, which works though it is by no means perfect. I am trying to find another solution, either an out-of-the-box component that can switch the ground and power or a new circuit design that uses less power - less voltage drop.

Any ideas are welcome.

simulate this circuit – Schematic created using CircuitLab

Figure 2. Redrawn version of OP's schematic with current flow from top to bottom.


texts:
I have 2 devices with analog signals. I want to acquire their signal with 2 MCU's (preferably ARM). fully synchronized with the same sampling frequencies, starting and ending simultaneously user controlled (for example by pressing a button).
I know that if I could connect them together via wires, I could use oscillator and triggers for this.
But is there any way to do this over WiFi?
Thanks


texts: What is the best way to connect 6S lipo 22000mAh to step down converter?

texts:
Can I use below step down converters with the battery below?

I will be using multiple step down converter to supply to other boards like (IntelUp_Squaredboard,motordriverboard).These are the links to my step down converter.
Step_Converter_1 , Step_Converter_2 . Let say if my board need 6A,should I buy exactly output 6A converter or 8A output converter?

Thank You All.


texts: Drive 8 Stepper motor simultaneous with different motion?

texts:
I have the need to drive 8 stepper motor together and with different motion behavior for each. Could I just get away with 8 stepper control board (easy driver) + an Arduino with enough pin to get the STEP/DIR from each driver and orchestrate all those motor with a nice code.

Or is there more thing to take in consideration ? More advance driver, or more powerful uC ?

Thanks in advance for any tips/suggestions.

Cheers,


texts:
For a lighting project, I want to power 12 programmable LEDS (WS2812b or equivalent) in series, and then have 5 of these sets in parallel. Due to extra resistance, I think I need a constant voltage source of 72V*. Dedicated 72V sources are surprisingly expensive, and as I need only some 300 mA I figured I should be able to convert from e.g. a 36V power source. I found many ways to do this, but I don't know which one will be stable enough for these kind of LEDs. I couldn't find any articles that go into enough detail to answer this without being full-fledged electronics books that are a bit too hard for me to follow.

Is my assumption correct that I should get a constant voltage source? I suspect a constant current source would mess with the integrated circuits, is that correct?
What would be the best way to achieve the 72V?

Chaining two 36V supplies? Straight forward, but is this stable enough, and how should I connect the grounds?
Voltage doubling circuit? Has simple components, but is it stable enough?
DC-to-DC converter? So many versions that I don't know which one is best.
Dedicated 230V AC -> 72V DC supply, more expensive option, but straight forward.

Thanks for helping out!

* For artistic purposes, the power will actually be delivered through pencils instead of wires, which have a resistance on the order of 10 ohms each. I experimented with this with non-programmable LEDs and there it works fine.

EDIT: a schematic as suggested in the comments; this is what I'd like to set up, but then with 5 strings of 12 instead of two strings of 3.

As I'd like to make a snub dodecahedron:

with LEDs on the vertices and pencils as the edges, with some providing power and others providing data. Connection-wise, this is possible by injecting power and data at the 5 vertices of one of the pentagon faces and having the LEDs powered as 5 times a series of 12; there are not enough vertices to provide power to all LEDs in parallel without injecting power at more points, which will make it less pretty.


texts: Connectors for access to four conductors from a 40-wire ribbon cable

texts:
I have a Raspberry Pi project I'm working on that will involve connecting three printed circuit boards. I'm trying to figure out a rugged and convenient way to make the connections. The drawing below is a side view of my current rough concept for how to do this. I'm hoping for feedback or suggestions on how to flesh out this plan or what would be a better plan. I'm inexperienced with DIY electronics, and what experience I had was 30 years ago.

The bottom board has a 2x20 pin header with a pitch of 0.1", as does the other large board above it. They're designed to work together, so I can just connect them with a ribbon cable, and the pinouts will match up correctly. There are also holes pre-drilled in the boards so that I can provide appropriate mechanical support, uniting these two boards into one rigid unit.

The hard part is getting the connections to the third, small board, which is a GPS receiver. It needs four connections: ground, 3.3 V power, and two UART lines. My current thought is to take a razor blade and carefully separate out the four wires from the ribbon cable, send them to some kind of connector (the circle marked "?"), and then go from that connector to soldered connections on the small pcb.

Issues I'm worried about:

The 3.3 V power line is also needed by the top large pcb, so I'd need to splice in an extra piece of wire to get that connected to both it and the small pcb.
I don't know what electrical properties are required for the UART line in order to avoid problems with things like reflected signals. The data sheet (link above) describes various speeds in various setups, but maybe 9600 baud. This seems relatively low, so maybe this kind of RF engineering stuff is not relevant?
I'm not sure what kind of connector to use. This is supposed to be a lightweight, compact unit. Molex seems like overkill. D-SUB seems kind of big and heavy.
I'm imagining a tendency for the ribbon cable to fray or split from the places where I separated the four strands from the main cable.
Not sure how to do appropriate strain relief for the soldered connections on the small pcb.
If I want to get access to other lines later, I have to do more razor-blade surgery. This suggests maybe using a crimp-on connector in the middle of the ribbon cable, but I'm not clear on how to make permanent connections onto such a thing.


texts:
I want to make a low-cost solution regarding the control of a three-phase AC asynchronous motor. I want to be able to control it using an Arduino board(set the frequency from it).

Motor specification:

Power: 0.3KW
rotations: 1400
Nominal current 1A at 220Vac/0.6A at 400V

I am relatively new into power-electronics, so it would be highly appreciated if you could tell me what circuits would I need?

So far I understood that I need an inverter circuit for the 3 phases of the motor. Do I need special controllers for every IGBT or can I control all of them from the Arduino?

Also, is this schematic remotely ok? If not, where could I find a complete schematic?


texts: I am trying to find information on pulse capacitors but there are too many options. Some vendor marked with metalized film capacitor,ceramic capacitor. In particular, I even don't know how to figure out what category should be used.As you known,most vendor suggest their own series only. I know about selecting voltage ratings at least 20% higher than the max possible voltage, or even more cautious selecting at least double the expected voltage. But for pulse grade capacitor,the more important points are its peak current performance and lifetime(pulse time).


texts:
Wikipedia says that the frequency of light is 300 THz.
I've made a radio waves transmitter that transmits about 100 MHz.

If I increase the frequency of the transmitter to 300 THz, will the antenna produce spark or light ?

Can I do this circuit practically o_O ?
Is there any transistor or IC that can oscillate 300 THz ?
Can I find an inductance ( coil ) of 0.0025 pH and capacitor of 1 pF ?

I know that it is a science fiction question but please, don't make fun of me :)


texts: Converting Clipping stage of guitar pedal to a formula for use in DSP

texts:
Been trying to figure out the clipping stage of a tube screamer so i can implement it in a DSP project.

I can simulate a clipping effect by using a tanh(input) type function, which gives me an OK approximation, but the R4,C3 high pass filter in the feedback loop is what i'm having trouble with.

I've designed an IIR high pass filter with a ~700Hz cut off point, but i don't know how to properly "fit" it into the code. If i apply filter AFTER the tanh(input) function, it's the equivalent of removing C3 and adding it in series (with a 4.7k resistor to gnd) at OUT pin.

If i apply it before tanh function, it's the equivalent of adding a high pass filter to IN signal, then Clipping..

Regardless i can't get that phase effect from the feedback that i see when simulating this circuit.
(NB: Simplified with no low pass feedback cap, etc)


texts:
I am driving a brushed DC motor (internal to a linear actuator) off of TI DRV8872 motor driver. I am PWMing the motor driver at 20kHz and varying duty cycle to control the speed. The problem is that the motor driver output lines are very noisy on the edge transitions and this noise is getting onto the rest of my board. See scope capture of the motor driver input (pink) and motor driver output (blue).

 As you can see, the output is not a nice square wave but has weird behavior on the edges.

I tested other brushed DC motors with the exact same setup and did not see this at all. In fact, it was a perfect square wave as expected. So from that, I was able to conclude that my driver setup was correct and the problem was related to the brushed DC motor load (inside of the linear actuator). I took apart the linear actuator and noticed that the specific one I was using had three 0.1uF capacitors soldered to it (one in between the motor terminals and one from each terminal to ground). As I understand, this is commonly done to prevent the arcing of the brushes from causing noise. The other ones did not have these capacitors. Once I removed the capacitors, everything worked as expected, so it seems the capacitors are causing issues with the PWM drive.

However, since the capacitors are internal to the linear actuator and the company says they are necessary for CE compliance, I can't remove them. My questions are:

Why/how are the capacitors causing this weird behavior in the first place? Shouldn't the capacitors actually help by providing a source of energy for the current to quickly pull from?
Why do none of the other linear actuators have capacitors, but are somehow still CE compliant?
Is there any way I can work around this to PWM drive the brushed DC motor?


texts:
Can anyone explain why some engineers use multiple parallel identical capacitors on MCU power inputs, memory power inputs... Sometimes there is up to 6, 7 or even 8! Here is one example I found for LPC4088.

This is confusing to me because I usually use one big electrolytic capacitor (to deal with low frequency ripple) and one small ceramic capacitor (to deal with high frequency noise) in parallel... Just like it is described here.

Does it have anything to do with input impedance of VDD/VDDR pins in the image? VDD is 3.3V and is supplied through a regulator LM117-3V3 like this:

I can't seem to find the info about input impedance for VDD and VDDR pins anywhere in LPC4088 datasheet.


texts: ESP12 Voltage Divider on ADC for battery capacity

texts:
Since I received GREAT feedback on my first PCB design here (and it works!) I have decided to design a second (improved) version.

In this version I would like to be able to measure the source battery voltage so I can translate that to an estimated battery capacity.
For this I'd like to use the ADC pin on the ESP12. On this pin I made a voltage divider because it only measures up to 1V.

Is this a working and the best approach for a beginner to estimate source battery capacity on the ESP12?

Someone suggested placing a .1Uf capacitor between GND and where the ADC reads. What would this do?

To get around the strain on the battery caused by this divider setup, should I put it behind a NPN tranistor?

the source files are all in the project on GitHub

Trace Thickness

Did I make a mistake here?

EDIT - Thicker traces and antenna free
It also looks like this voltage divider is ok, I have tested it on a breadboard. The voltage divider power consumption is 0.0074mA if I calculated that right :)
[6


texts: Is the output from a 120V 300W UPS enough to kill a person?

texts: I recently got an old APC BK300 UPS  (Input:120VAC & Output:120VAC 300W) along with many other  vintage electronics stuffs. So I tried opening the the UPS completely.I noticed that the battery a 12V 7Ah BB battery SLA was completely dead. Well I kinda added som edistilled water and revived it and it seems to be working fine now after a day of charging with a high power automotive charger and put it back on the UPS after resealing the SLA. I removed the UPS buzzer since it was kinda annoying. Connected the SLA and powered up the UPS and connected a 130V 100W bulb and it was glowing bright.I usually do some power electronics stuffs from mains and having been looking to replace the mains as source with an inverter or UPS(always feared getting electrocuted). So does a UPS has enough juice to kill me like power from mains 110V outlet? Also there are two transformers inside the UPS a really big one and a small one on the circuit board.Which one is the inverter transformer? I've posted some pics below.


texts:
I've been taking a close look at PSoC chips (series 1 in particular). With the reconfigurable analog blocks, they seem like a great solution for general data acquisition needs for prototype projects.

I'm thinking about buying the programmer ($37 academic) and a few PSoC 1 chips so that I can avoid building amplifiers and filters and design electronics in a more intuitive way (more like Max/MSP).

Here's the signal chain I'm looking at for my current project:

(noisy) textile resistive sensors => voltage divider => PSoC(amplifier => lowpass filter) => (Xbee => Xbee?) => Teensy((decodeXbee|ADC) => micro-OSC code => USB) => Max/MSP/Jitter

People didn't have much good to say about PSoC in the last thread. Do you think they're overkill for general signal processing tasks in prototypes? Not worth the convenience? Wait a few years for the bugs to be ironed out?

Edit 1: I'm not looking for the best solution for my current project, I'm curious as to whether you think PSoC is a good investment for general prototyping. I see two advantages for myself:

I get to learn (and share with the local community) a new technology
When I need to do signal processing in prototypes, rather than hunting for circuits, spec'ing parts, ordering them, waiting, then assembling them, I can whip out a PSoC, configure the blocks I need, and plug it into a breadboard

This was prompted by the answers to a previous question I asked here. I thought, rather than buying and learning to use PGAs and instrumentation amplifiers, I could get to know PSoC and turn a hardware problem into a software problem.

Edit 2: I ordered the MiniProg1 kit from NKC Electronics. I'll let you know how it goes.


texts:
I am using 20X4 character LCD display.
Like these:  https://www.alibaba.com/product-detail/big-size-20x4-line-white-color_62471561311.html?spm=a2700.pc_countrysearch.main07.78.2bafd2a7u344W2
The operating temperature rating is maximum 70 deg. cel. and I read that UV rays damage the LCD screen.
Are there any products or protective films that I can apply to protect from UV rays or direct sunlight?


texts: How to output a voltage proportional to the speed of a DC motor?

texts:
Take a DC motor, as the one in the picture below:

I need some kind of analogic signal (preferably proportional to the speed of the motor) that can be used in a control loop.

What are two simple ways of achieving this? (One would be enough as well). If you have experience with some specific parts, please do supply the part number too.

I thought about using a hall effect sensor, but that would give me a digital signal and I wouldn't know how to filter it properly....


texts: If I have a 12 V car battery and I connect it to a 3 kW 10 A 220 V AC inverter, how much would be the current draw? 250 A?


texts:
I have a spare DMM (Digital MultiMeter) that I would like to use to log the displayed data at 1 sample/sec.

What would be the least expensive way to mod the DMM to log the data that appears on the display?

I know that the meter data goes though an AC/DC converter, ADC, decoder, & then to the display.


texts: Total resistance with resistors bridging two branches

texts:
I know how to calculate resistance in parallel and series connected resistors, and how to reduce most circuits to these, but I missed my lecture on cases where you can't just reduce the circuit to series and parallel and now I'd like to catch up...

simulate this circuit – Schematic created using CircuitLab

How to calculate total resistance between A and B in such case? R5 rains over my parade because I don't know a'priori which direction current will travel through it, and I don't know how to transform this into something I'd know - I could try to calculate potentials at points p1 and p2, to get the current that flows through R5, except that current modifies these potentials...

How do I solve a circuit like this?


texts: Is it possible to model a microwave resonator in SPICE

texts:
I just wanted to know if it was possible to model a microwave resonator in spice software or somehow import it from somewhere to spice to carry out analysis.
Also if it is not possible to model the microwave resonator in spice, will using a series or parallel resonance circuit be able to 'replace' the microwave resonator/cavity.
I would be grateful for any help.


texts: Why do the center tapped capacitors in Colpitts oscillator give an inversion?

texts: In Colpitts oscillator, we have two capacitors in series, with the middle grounded. It is said in explanations that in this way, the signal from the output of the amplifier is phase shifted 180 degrees and therefore a desired ratio is fed back into the amp. But why does an inversion happen here? By my logic, since the output of the amp is in reference to ground, all the current should from through the first cap (here C1) to ground. So why is the signal inverted after the second cap on the base of the transistor?


texts:
I need to design a mil-std-1553 analog front end transceiver  to already designed digital 1553 ip for my ms thesis.  So I need to convert digital 3.3V to analog specs level and receive and convert to digital 3.3V level. As a newbie designer and of this protocol, I did some reads on the standart of the protocol. I know little bit about system of transmitter and receiver of the protocol. Such as filter, driver blocks etc. I have some infos about alternative supply solutions and transformer issues. But I have no further detailed ideas to use as a transceiver design starting point as a new graduate.  I do need detailed knowledges about filter types that is used in receiver and other design details that I havent consider yet.
Any guidence about it will be really appreciateble.


texts: How to know if questions in an exam mean line, phase, or RMS voltage?

texts:
What is the difference between line, phase and RMS voltage?

We get many questions where it is not mentioned whether the question is specifying line, phase or RMS voltage. I will attach some example questions to be more specific:

In all the three questions, how do you know if it means line, phase or RMS voltage?


texts: Derivation of the transfer function of a instrumentation amplifier

texts:
I've just been really frustrated because I've been trying to understand this information online about how the transfer function of an instrumentation amplifier is derived. It would be really helpful if I could see this using circuit analysis but I cannot. I have been trying to make sense of this article here:

https://masteringelectronicsdesign.com/how-to-derive-the-instrumentation-amplifier-transfer-function/

Basically I understand the first half of the article where it explains that the transfer function of the difference amplifier can be derived using superposition (That is grounding one of the inputs to the op amp whilst having a voltage on the other and finding their effect on the output voltage using KCL).

The derived equation is as follows:

$$ v_o = v_1\frac{R_2}{R_1+R_2}(1 + \frac{R_4}{R_3}) - v_2\frac{R_4}{R_3} $$

For this op amp circuit (where one of the inputs is grounded to find the effect of one input on the output):

It then tries to prove the transfer function for the instrumentation amplifier using the method of superposition as well starting with this image below:

Claiming the following:

$$V_{out1} = \frac{R_2}{R_1}(V_{11}-V_{12})$$

Claiming that the derivation of the transfer function for the difference amplifier is proof. I don't see how this expression is proven. I have tried using circuit analysis to get this result and I cannot see how this is a viable expression for \$V_{out1}\$ if \$V_{2}\$ is grounded.

So far I have been trying to solve it by just imagining the two inputs \$V_{11}\$ and \$V_{12}\$ going directly into the input of the final op amp but it turns into a mess of algebra that makes no sense.

If somebody could show me how this is derived I'd greatly appreciate it.

Simon.


texts: Circuit or component to detect temperature change

texts:
I know this is a very simple question but I didn't find the answer. I have very less knowledge in electrical.

I want a component or a circuit or whatever, which I can attach to a heating coil so that after a specific temperature threshold, the supply should get cut off.

Ex. Suppose I am applying 120V to a resistive coil. Now it will start heating from 0 temperature (degrees) to higher... I want the supply to be cut off when the coil heats up to say 100 degree celcius.

Thank you


texts: Looking for Amp connector family name for connector similar to Molex Mini-Fit Jr

texts:
I recall having used a connector family from Amp (now TE) that is very similar to the Molex Mini-Fit Jr family.  These connectors are NOT interchangeable.  The Amp connector has round pins, the Mini-Fit Jr connector has square pins.  However, the body styling is very similar, both in size and polarization keying.
I've been searching but can't seem to find that family.  Can anyone tell me the family name or typical part number?


texts:
I am trying to make a 8 way demultiplexer in hdl. The hdl is nog vhdl or verilog. It is interpreted specially for a nand2tetris cursus.

I try to get something like this

| in  |  sel  |  a  |  b  |  c  |  d  |  e  |  f  |  g  |  h  |
|  1  |  000  |  1  |  0  |  0  |  0  |  0  |  0  |  0  |  0  |
|  1  |  001  |  0  |  1  |  0  |  0  |  0  |  0  |  0  |  0  |
|  1  |  010  |  0  |  0  |  1  |  0  |  0  |  0  |  0  |  0  |
|  1  |  011  |  0  |  0  |  0  |  1  |  0  |  0  |  0  |  0  |
|  1  |  100  |  0  |  0  |  0  |  0  |  1  |  0  |  0  |  0  |
|  1  |  101  |  0  |  0  |  0  |  0  |  0  |  1  |  0  |  0  |
|  1  |  110  |  0  |  0  |  0  |  0  |  0  |  0  |  1  |  0  |
|  1  |  111  |  0  |  0  |  0  |  0  |  0  |  0  |  0  |  1  |

Instead I get this:

| in  |  sel  |  a  |  b  |  c  |  d  |  e  |  f  |  g  |  h  |
|  1  |  000  |  1  |  0  |  0  |  0  |  0  |  0  |  0  |  0  |
|  1  |  001  |  0  |  0  |  0  |  0  |  1  |  0  |  0  |  0  |
|  1  |  010  |  0  |  0  |  1  |  0  |  0  |  0  |  0  |  0  |
|  1  |  011  |  0  |  0  |  0  |  0  |  0  |  0  |  1  |  0  |
|  1  |  100  |  0  |  1  |  0  |  0  |  0  |  0  |  0  |  0  |
|  1  |  101  |  0  |  0  |  0  |  0  |  0  |  1  |  0  |  0  |
|  1  |  110  |  0  |  0  |  0  |  1  |  0  |  0  |  0  |  0  |
|  1  |  111  |  0  |  0  |  0  |  0  |  0  |  0  |  0  |  1  |

I can't find anything wrong with my hdl code. Maybe I have overlooked something? Does somebody see a reason it doesn't work.

My hdl program looks like this:

CHIP DMux8Way {
    IN in, sel[3];
    OUT a, b, c, d, e, f, g, h;

    PARTS:
    // Put your code here:
    Not(in=sel[0], out=notSel0);
    Not(in=sel[1], out=notSel1);
    Not(in=sel[2], out=notSel2);

    And4Way(a=notSel0, b=notSel1, c=notSel2, d=in, out=a);
    And4Way(a=notSel0, b=notSel1, c=sel[2], d=in, out=b);

    And4Way(a=notSel0, b=sel[1], c=notSel2, d=in, out=c);
    And4Way(a=notSel0, b=sel[1], c=sel[2], d=in, out=d);

    And4Way(a=sel[0], b=notSel1, c=notSel2, d=in, out=e);
    And4Way(a=sel[0], b=notSel1, c=sel[2], d=in, out=f);

    And4Way(a=sel[0], b=sel[1], c=notSel2, d=in, out=g);
    And4Way(a=sel[0], b=sel[1], c=sel[2], d=in, out=h);
}


texts:
I have just come across this data sheet that specifies values from a timing diagram as

  \$t_1\$ φ 300 ms, \$t_2\$ φ 50 ms, \$t_3\$ φ 25 ms, \$t_4\$ φ 15 ms,
  \$t_5\$ = 5 ms (minimum), \$t_6\$ φ 100 ms

The φ seems like maybe some kind of equivalence symbol.  Any definite meaning?


texts: Do you think this board can be done in 2-layer or should I go to 4-layer?

texts: Here are 3 photos of the board I am trying to build. The photos are the top, the bottom and the bottom with the analog portion (Buffer+ADC) inside a red box. It is an ohmmeter. Most SMD parts are on the bottom. The large through hole part is the 7-segment LCD on the top with the uC underneath it on the bottom. Before I start routing, I was wondering if I can still do this in 2-layer or would it be too difficult to try and route. Also, I wondering if I should isolate the analog somehow, like a split ground plane. Any criticism is welcome. Thanks.


texts: I am reading an article on the USB Spec and it mentions that "For CRC generation and checking, the shift registers in the generator and checker are seeded with an allones pattern." Here's the full article. What is an allones pattern?


texts: 555 Timer - How to quickly discharge RC capacitor

texts:
I'm using a 555 timer to turn off an LED with delay.
Here is the circuit.

All I want to implement is, to get the input voltage changes in output with a constant delay.

When I close the switch, the capacitor in RC network being charged and the OUTPUT will be LOW after n fraction of time. But, after opening the switch, it takes time for capacitor to being fully discharged.

A. Is there a way to discharge it quickly? B. And is there a more simple implementation without using 555 timer? C. How can you revert the output from LOW to HIGH instead of HIGH to LOW?


texts: How can I get rid of this spike in my overvoltage protection circuit?

texts:
simulate this circuit – Schematic created using CircuitLab

I am trying to design an overvoltage protection circuit. And this is the circuit above, and this is the LtSpice circuit below:

This circuit somehow manages to function correctly. Meaning, it accepts input only for voltage level between 2V -3.6V, when higher voltage is applied, it closes the PMOS (M4 in CircuitLab and M1 in LtSpice).

But the problem is ripple and the spikes! I know spike is formed because M1 can not open fast enough to compansate fast rise of Vin to gate of M2. But I can't think anything for getting rid of ripples.

spike occurs at both circuitlab and ltSpice.

But in circuit lab, ripples not seen.

Thanks in advance.


texts: How would my circuit vary if my DS18B20 comes on a 'Keyes' module?

texts:
I am looking at the following tutorial on how to link the DS18B20 to an esp32 module: https://randomnerdtutorials.com/esp32-ds18b20-temperature-arduino-ide/

For the parasite mode, I have the following diagram:

I have a Keyes DS18B20 module instead: https://www.tautvidas.com/blog/2015/09/measuring-temperature-with-ds18b20-temperature-sensor/

I was wondering how that would change my circuit? Would I just replace the resistor on the diagram with a wire?


texts:
All right, I don't get it.
I tried and tried, but I just don't understand.
I have a dozen questions about this so somebody just pick one out all of these, I don't care.

What's inside a North American residential 240V pole transformer?

Is it (secondary) double iron core windings with 120V on each core and each end of the coil has one hot and one neutral wire that get tied in series to add up to 240V?

OR

Is it a single iron core winding with two hot wires on each end and a center wire tapped at the 120th winding to make a 120V wire?

Are there two sine waves in a (secondary) double iron core transformer or one?

OR

Are there two sine waves in a (secondary) single iron core center tapped transformer or one?

If either of the two types of transformers do truly have two sine waves, are they 180° opposite from each other at peak?

OR

Are they 90 degrees out of step from each other at peak?

OR

Are they on top of each other?

Please don't use to many equations or symbols, because I've exhausted my explanation abilities as it is with these questions and might not understand much more than the simple words that were already used here.


texts:
Let say we have a very short pulse (100ns to 4000ns) and we want to make another wich last 1000 times longer so we can mesure it with a microcontroller.

We don't really care if the multiplication factor is accurate, neither if is really linear (vs logarithmic), but we want it to be coherent and repeatable : same input pulse should give same length output pulse.

I'm thinking of a capacitor A discharging in another capacitor B for mesuring the initial pulse, then discharging B trough a strong resistor so it discharge slowly.

Does this kind of timer works at ns resolution ? Is it reliable ? Is there a better way to do that ? (is it the worst ? :) )

---- Edit for good EM Fields questions

Accuracy of multiplier factor could vary between devices, something between x1000 and x5000 will be ok. But it must be stable for one given device within the same conditions (temperature, pressure...) over a 5s timespan. I want to be able to measure the initial impulse with an accuracy of 3ns, wich means 3 to 15µs jitter on the output pulse depending on multiplication ratio. It is more important to have a better accuracy on short pulses. I think and average of 1/500 of total duration is enough. Plus, maybe a kalman filter or something alike could smooth out this jitter.

We don't care about multiplication factor because the system will calibrate itself between every measures. There will be one known duration pulse, then one information pulse. We need to know the ratio duration_of_information_pulse/information_of_known_pulse.

The goal is to locate a device on a field using time of flight of a radio signal. It requires 2 measures. One position every 10s is enough. So we don't really care when the output pulse start.

------ Progress

I found this patent https://www.google.com/patents/US3712993. Looks like it uses Tcd and Tpd of cascading transistor. I don't think it is suitable for x1000 multiplication factor.


texts: Hole diameters in PCB software - finished or tool size?

texts:
Should I specify the diameter of holes on my PCB as before plating (tool size) or after plating (finished)?

Michael Leonard says finished

Olimex says tool sizes

Pcbex says finished

...

Thank you for any thoughts.


texts:
I am trying to print pdf of negative artwok in the altium.  I am adding full fill on the board different layer. Then change layer color( make black and white ) through Page Setup>Advanced>Preferences. But I cannot color the holes. Some old altium versions have pad hole color and via hole color but I am using Altium Designer 16, where I am unable to find the options.
Question: how to enable the color options for pad holes in Altium?

I trying to make negative artwork pdf. Here my result.

I want to make black holes but it's grey.


texts: Can I connect 10 AWG wire carrying up to 25 amps to 10 parallel 1 ohm 10 watt resistors?

texts:
I am trying to measure the charge capacity of some LTO battery cells. To do this I want to discharge each battery cell from 2.5 V to 1.7 V. I am going to measure and log the current over the discharge cycle and then integrate the obtained function over the testing time. Of course I would not have to do this if I had a constant current load, but I do not.

The cells are 20 Ah and I want the test to be quick. Thus to make the test take only an hour, the cell should be discharged at an average of 1 C, 20 amps. The cell is rated for up to 10 C so it is not a problem to go as much as 25 or 30 A if my set up can handle it.

Is the following set up feasible? One LTO cell charged to 2.5 amps connected to 10 AWG wire connected to a uni-direction Hall effect current sensor. The current sensor which is rated for up to 50 amps is then connected to 10 parallel 1 ohm resistors rated at 10 watts each. The other end of the resistors must then be somehow connected back to 10 AWG wire to connect back to the negative battery terminal. Each resistor will carry at most 2.5 amps at 2.5 volts for a maximum wattage of 6.25 Watts, well under the 10 watt threshold. The resistors are just there to dissipate the energy.

I am most concerned with how I could safely connect the 1 ohm resistors, which are rated for 10 watts but have 20 AWG wire leads, to the current sensor that is going to output up to 25 amps. Additionally will the heat generated by the resistors be a problem?


texts: What consumes the most power in a computer

texts:
I have a quite basic question:

As far as I understand (correct me if I am wrong), we can summarize a computer by saying it is composed of wiring, transistors and some electronic components like capacitors for example.

The electric consumption of a computer mainly come from heat dissipation if I am not wrong.

Does this heat dissipation mainly comes from Joule effect in the wiring between the components, or from the components themselves (transistors) ?


texts:
The manual of a computer processor usually includes a description of something called programmer's model. This section normally presents the core registers of the processor, operating modes, endianness and the instruction set.

I think the term refers to an abstract model that describes how a programmer should use the core components of the processor to program it. But I'm not sure whether I'm right or not, so I'm looking for a formal definition.


texts: Power supplies separation in PCB for an Arduino-like Shield

texts:
I could not find a cut-dry answer anywhere on this issue and I'm struggling a bit on the design of a PCB.
Note, this is the first time I design a PCB, and this issue is actually not so relevant, but still, for the sake of learning I'll post the question anyway.
The shield consists of a DAC driving various transconductors.
The DAC is a multi-channel nanoDAC from Texas Instrument.
I'm planning to build a 4-layer PCB.
The ground plane will be split between the DAC and the transconductors (but still connected on a point).
The power supply plane will be also split in two. However, I will have to deal with 3 different supply voltages and I'd prefer to not split the plane even more:

The (up to) +30 V for the transconductors
The DAC power supply (from 2.7 V to 5.5 V)
The logic voltage level (from 1.6 to 5.5 V)

For the sake of flexibility, I'd like to have the option to power the DAC with the 3.3 and 5 V supplied by the Arduino, but also an external power supply. I'll do that using jumpers.
I'd like to have the same flexibility for the logic level and use the IOREF pin of the Arduino or another external reference. Is it ok to just connect the logic level with a wire track, even on the opposite side of the board? Is it bad practice? I'll connect the logical inputs to this same voltage...


texts: I am not understanding something very fundamental here , I have read that an RC circuit can be used as a clock source. From this I assume a DC input. Playing around with my oscilloscope the only time I see an RC circuit oscillate is with an already oscillating input, throwing in a DC input there is no oscillating just the obvious blocking of DC by the cap, so how does an RC circuit work as on oscillator with a DC input? And I know you can make fancy ones with more components but I mean a very simple resistive/capacitive circuit? Thanks in advance.


texts: Can you power this opamp with a single regulator?

texts:
I am reading the data sheet here http://www.ti.com/lit/ds/symlink/opa1664.pdf, and it says:

Wide Supply Range: of ±1.5 V to ±18 V, or +3 V to +36 V

Does that mean I can connect V+ to +5V and V- to ground of a typical 5V linear regulator?


texts: Limiting output current of a Buck Converter

texts:
I am trying to power a 4S-ESC to drive a BLDC motor using a buck converter and 24V,10A SMPS. However, my buck converter can only handle 10 Amps of current (safely) at 15V through its output side. Therefore, I need to make sure that the output current should not go over 10A, even if I increase the throttle input to ESC. Also, I do not want to put a relay triggered by a current sensor, since that will shutdown the power supply to my motor, which is undesirable. Thus, I want to 'limit' (or 'saturate') the current at 10A.

Is there a way to achieve this without hacking the buck converter?

If there isn't, these are the details of my buck converter-

Description : Non-isolated adjustable synchronous buck module

Rated Power : 200 W

Input Voltage : 8-55V

Output Voltage : 1-36V

Output Current: 10A

Operating frequency:180 kHz

Buck Converter Controller IC datasheet (click here)

(for more details - click here )

I am also sharing some photos for the other components and their placement,

EDIT :
Thank you everyone for your inputs.

The photographs are for reference only, the buck converter seen in the photo is an old one (fried it up sometime back). Also, just to make it clear, I don't want to 'cut-off' my power supply or make a 'constant current' buck. What I really  want is to 'set' a max value of current for my buck so that 'no matter what' the load does not draw a higher value of current from it.

Looking to achieve exactly this (see video) for my own buck! Thanks!


texts: How to reduce noise for arduino capacitive sensing

texts:
I have an artistically-painted 5mm-thick wood panel that I want to use as a light switch without alteration to the image. My solution was to (try to) make a specific region on the panel touch-sensitive using an arduino and the CapSense library, and use a relay for switching.

I connected the capacitive sensing wire to a piece of aluminum foil taped directly behind the region of the wood panel that I wanted to be touch-sensitive. I got this to work perfectly when the arduino was powered by my laptop, but when I connected it to my cheap 5v 700mA power supply, which was connected to main, the noise was too much.

After reading a little on noise reduction, I tried connecting a 1000uf capacitor in parallel with the transformer -> arduino line. That seemed to help, but still was far from fixing the problem.

This is where I'm stuck. I ordered more capacitors, but figured I'd post the problem while I wait. Is more capacitance the answer, and if so, how much? Are there other tricks / common practices for removing transformer noise that seem like they'd probably be useful here? Or should I be using a different method of capacitive sensing than the digital delay-based CapSense library?


texts: Are there any battery chemistries that can be fabricated at home?

texts: My question is simple. How hard it would be to fabricate a Battery of customized shape say of 30cm x 30 cm x 0.5 cm that can be fabricated by DIY without requiring any specialized/ hazardous chemicals or manufacturing processes that can be easily fabricated in garage setup with upto 500mA operating current and capacity in mAH range upwards of hundred? Does anyone know any chemistry that can achieve this?


texts: Why does a buffer amplifier change the behaviour of a bandpass filter?

texts:
Why does the implementation of a buffer amplifier separating the high-pass and low-pass filter of a bandpass filter affect the transfer function of the bandpass filter?
I thought the point of a buffer amp was to keep the output voltage equal to the input voltage regardless of current draw at the output. Therefore I would expect there to be no change assuming no current is being drawn at the input or the output and all components are ideal.
Unfortunately it seems the transfer function of both filters and their behaviour is different and I don't know why.

Buffer amplifier present:

simulate this circuit – Schematic created using CircuitLab

Buffer amplifier not present:

simulate this circuit


texts: Calculate capacitor to hold up current limited supply

texts:
I am designing a capacitor bank to hold up a current limited supply when a resistive load is switched by an NPN transistor to ground

The power supply is 2800V limited to 400mA and I require to draw 1.8A for a 15ms pulse.

How do I begin calculating the capacitor value I will need to hold the supply up with 150V maximum droop for 15ms (I'm looking for methods rather than answers, but it was easier to explain with the real numbers)

simulate this circuit – Schematic created using CircuitLab


texts:
I have a timing circuit application that depends on the intervals with duration determined
by an RC circuit. When a capacitor is [dis]charged through such a circuit, a voltage level across the capacitor between the levels at the beginning and the destination is visited only once for a single time
interval. Can you explain why?


texts: MOSFET's getting too much heat up without any load

texts:
I am working on inverter, MOSFETs in h-bridge inverter goes heat up without any load attached. I also attached pull-up and pull-down resistor on it. here is my circuit duagram.

EDIT

Sources of PMOS are connected to supply and sources of NMOS are connected to ground.

Output waveform and voltage are all good but have heating issue is not resolve.
Any suggestion or modification is very helpful for me.


texts: Why is erasure much slower than write for (NAND) flash?

texts: Typical block erasure time for NAND is on the order of milliseconds which is one order of magnitude higher than write. Both of them are based on FN current. Why? Thank you!


texts: Troubleshooting Switch Mode Power Supply

texts:
I am trying to troubleshoot switch mode power supply from HP workstation. I have done visual inspection and didnt find any anomalies on the capacitors. I reckon that the culprit might be the fuse as there is absolutely no light nor fan movement when the power supply is connected.

Before proceeding I have two questions:

Is it safe to permanently remove heat shrink (without replacing)
on various components?
Is the location of the fuse is in the area
circled yellow in the image?


texts: Setting up a PID controller in Simulink for an Arduino example project

texts:
On the internet I found this "Arduino PID Example Lab" as an introduction to PID-contole. I set up the hardware and it is working like it is described in the document.

Since it is possible to connect Simulink with the Arduino as it is shown here, it would be nice to simulate the PID-control in Simulink. The needed Support Package for the Arduino is published here. After simulating the contole it could be connected to the Arduino to change the parameter while running. I managed to interface the arduino (read analog / digital values) and sent digital (PWM) signals. The main problem is about setting up the PID:

\$u(t)=MV(t)=K_pe(t)+K_i\int_o^t \!e(\tau)d\tau*K_d\frac{d}{dt}e(t)\$
src: Arduino PID Example Lab (1.1)

And to make it compatible with the analog input and the PWM output to the board.
So far this is what i got:

Status-update:


texts:
I'm trying to build a control system which I control variable x with a feedback y, goal is to find the maximum value of y while avoiding overshooting as much as possible. Assume y has a well defined shape with one maximum (so there're no local maximums to confuse the system), like the one shown below.

I looked up PID control loop and while the principle seems to apply but it requires a user defined set point, but in my case the target is the maximum which is unknown. How can I modify PID for it to work in my case?

On a separate note, the feedback value y has noise on it. It is not a big issue when x is away from the maximum as the slope is high, but it becomes an issue when getting close to the maximum as the slope becomes flat. How can I mitigate the noise issue and make sure the system is stable at the top?


texts:
Say for example you have an embedded peripheral BLE device which has a single BLE service with some characteristics and the initialisation order is always the same (service is added, then characteristic A is added, then B and so on).
In my local testing, the handles passed to the central from the peripheral always appear to be the same. For example, the service has always been 0x000c, characteristic A 0x000d, etc.
This is the case even on disconnect/reconnect as well.
Looking at the Bluetooth documentation, I found this about attribute handles:

3.2.2 Attribute handle
An attribute handle is a 16-bit value that is assigned by each server to its own
attributes to allow a client to reference those attributes. An attribute handle
shall not be reused while an ATT bearer exists between a client and its server.
Attribute handles on any given server shall have unique, non-zero values. Attri-
butes are ordered by attribute handle.
An attribute handle of value 0x0000 is reserved for future use. An attribute han-
dle of value 0xFFFF is known as the maximum attribute handle.
Note: Attributes can be added or removed while an ATT bearer is active, how-
ever, an attribute that has been removed cannot be replaced by another attri-
bute with the same handle while an ATT bearer is active.

With this in mind, does Bluetooth allow clients/central to force the server/peripheral to re-initialise their services and characteristics?
Or is it safe to assume that once my user code initialised the services and characteristics, they will always have the same handles?


texts: Can you really overcharge a battery at its rated voltage?

texts:
Say I have a 12V battery discharged to 11V and I connect it in parallel with an AC adapter whose final output is 12V DC.
In ideal case any current flow towards battery should stop as soon as battery is charged to the same voltage as the charging voltage (due to 0 net potential difference between charger and the battery.)
Is it safe to leave the battery connected to the AC adapter or it will start overcharging?
In case of overcharging what is the mechanism when there is no potential difference (for any chemistry)?


texts: What is this plastic wrap used in electronics?

texts:
I will occasionally receive electronic components from China tightly wrapped in this plastic film. It's much thicker than general plastic wrap that's bought from the store and does a good job at adhering to itself when wrapped.

I have tried wrapping the same parts using generic plastic wrap for food but it fails to adhere; providing a loose wrapping that will unspool itself.

Is this material something used in packaging? Does it have a name?

Is this possibly some kind of wrappable heat shrink?


texts: Power supply noise problem in a measurement system

texts:
This might be a bit long to explain but actually a power supply noise is affecting a system's measurements. I will briefly try to explain the system and the noise issue with several pics. This is directly related to my previous question: How to verify observe or check the source of AC line noise

I'm using this [system][1] together with this [module][2](SECTION 4 shows ELECTRONIC COMPONENTS). This is a pressure scanner system. Basically the ZOC modules amplifies and multiplexes 64 pressure channels(500Hz sampling freq. for each channel) and sends the particular channel's analog voltage output(chosen by a decoder code sent from the system) to the RAD_unit which then converts this voltage to a digital by its ADCs and sends to a PC.

Here is the basic illustration of the system setup:

[![enter image description here][3]][3]

All system is fed from one AC mains outlet using a power strip.

Depending on the day, time of the day or powering the system through different AC mains outlets I was getting different magnitude of spiky noises in my measurements. Below shows this difference. Both voltage is on vertical axis represents sensor data and scaled with factor 100.(For example 10 in vertical pressure axis is 0.1 Volt). Here is a comparison of two measurements where the bottom is when there is spiky noise:

[![enter image description here][4]][4]

Later on I checked the +-15VDC power supply outputs(RPM100 in above illustartion) which powers the module and sensors, and I found out there is noise similar to the one in measurements.

Here is how the power supply connects to the module:

[![enter image description here][5]][5]

And here are some screenshots of the power supply's +15V to GND measurements from scope in AC coupling:

A very noisy situation:

In FFT view:

A less spiky/noisy situation:

[![enter image description here][8]][8]

And here when there is almost no significant noise(the gap is scope's artifact):

Question:

It seems to me there is a big correlation between the measurement noise and the power supply noise here. Power supply is very old at least a decade old but a special one and powers all the units with its special connector.

1-) What kind of power supply noise can it be? It is obviously effected by the AC lines)

2-) For a quick solution, Im planning to cut the cable and place 100nF caps between +15V to GND and -15V to GND. Do you think it can be a solution? And if so would 100nF be okay?


texts: MCU, N-channel MOSFET, ~15m led strip, 24V power supply. Whats happening?

texts:
Disclaimer
Hi,
Firstly, I'd like to underline, that I do not have masters degree from electrical engineering and I didn't study electrical engineering on high school. I'm software engineer who likes to experiment with MCUs.
This is what I'm using:

MOSFET: IRLB3034pbf
power supply: 200W 24V
MCU: ESP32 Wemos D1 R32
LED strip 24V ~15m-16m long
PWM 1kHz ledc

This is what I'm facing

When PWM is off, voltage between Drain and Gnd is 11V, between D and V+ is 14.7V
When PWM is on, voltage between Drain and Gnd is 9.3V
what I learn from mosfet datasheet, Vgs(th) = 1-2.5V (should be fine right? It's also optimized for logic level drive)
led strip works just fine when connected directly to powersupply or via 2.4G dimmer

Questions:

why there's 11V instead of 24V between D and Gnd when pwm is off
why there's 9.3V when pwm is on instead of near 0V
why LED strip is not working
is MOSFET not suitable for this use-case?
Why this circuit works with 45cm very same led strip?

Schematic


texts: Using Op-amp as comparator with low supply voltage (1.1v)

texts:
As part of a school physics project my group was given 2 TEC1-12706 and was told to find some way to generate electricity via Seeback effect and recycled materials. Due to low efficiency of the TEGs, we are only able to generate around 1.5~1.1V when connecting both TEGs in series during testing. Our idea is to connect the TEG to a pot and use it as an egg timer. Our circuit is as shown:

HA17393

At time = 0, the TEG will charge the capacitor.

Few seconds later, due to drop in temperature of hot water, Vse < Vcap, stopping charging of capacitor.

Few minutes later, the Vse < Vnon-inverting input (adjusted using the variable resistor), and op-amp's output will turn on, allowing the capacitor to turn on an LED, or some other device to indicate that the egg is cooked.

However, I am facing an issue with my circuit. Often, when the TEG voltage drops below the capacitor voltage, the capacitor begins to discharge quickly. This happens even if no output is connected to the op-amp. I suspect this is due to the supply voltage of the op-amp being less than stated in the datasheet (Vs = 2-36V). Is this indeed the case or have I made another design error in my circuit?


texts:
I have a soldering station designed for 110V AC only.  I live in Europe so I have to convert it to 220V AC if I want to use it. I thought to sell it but the shipping is huge (it weights 3+ Kg) so probably I would just waste my time.

Its internal power transformer has a label with the following info:

Model: YF-EI 66x36
Input: 110V/60Hz
Output: 10V 26V 30V (I couldn't verify this since I don't have 110V main AC but hopefully the info matches the transformer's outputs)

So I see only 2 solutions:

buy a step-down voltage transformer from 220V to 110V that would provide at least 700W (this is probably the most expensive solution)
buy a new power transformer from 220V to 10V/26V/30V and replace its internal power transformer with this one (this seems somehow cheaper than the other solution)

What would you suggest for this situation? Some advice/tips?


texts: X-bee and accelerometer: problem streaming data

texts:
Hoping someone might be able to point me in the right direction.

I am currently trying to create a wireless accelerometer using two x-bees (series 1). The accelerometer module is set up so that the x,y,z channels are connected to the DIO0, DIO1 and DIO2 channels on an x-bee explorer. The device is all powered through the 3.3V input on the explorer by a 3.7V (110mAh) li-po battery which is also connected to a usb li-po charger.

I have setup the x-bees within X-CTU and there is no problem communicating between them. DIO0, DIO1 and DIO2 are all set to ADC and i have set it using several different sampling frequencies. I have noticed within the terminal window that when moving the device both DIO0 and DIO1 appear to remain constant (FF 03 from memory) and only DIO2 seems to vary within each data packet. If i change the setup at any one time to only transmit the data from one of the three channels at a time, they all change with movement.

Any chance you might be able to guess where ive managed to mess it up. I am assuming that the wiring and power between the accelerometer and the explorer is fine given it works when only displaying one channel at a time but my experience with these things is limited so im stumped with where to go with it now... Just wondering if the x-bee requires more power for the ADC for all three channels and the it might just need more power to the device to work?


texts: I was looking at these led's, and was wondering if I cut them up into pieces of three LED's each, would I be able to power the three LED's to a decent brightness and an ATtiny85 with three of these AAA Batteries Hooked up in series? Would this provide enough Amps? With three LED's I'm thinking they will need about 20mA each which would be 60mAh. Am I correct on that? I couldn't find how much mAh these batteries are rated at, but could someone help me understand if this would work? If not, do you have any other suggestions on how to power an ATtiny and a 3 LED Strip cost efficiently and without taking up a lot of room (I want the project to be as small as possible). Also, if you know much about LED's would you suggest using any other type of LED like the WS2812's or WS2812B for a project like this? Thanks


texts: Noise caused by the separate power supply of the sensor?

texts:
For my experiment I built a circuit to record long-term vibration data. It consists of two types of sensors (proximity revolution and MEMS acceleration), Arduino, Raspberry Pi and power supplies, which are connected together as shown in the schematic.

The problem is that I have too much noise in my acceleration signal (see the spikes at the bottom). I suppose it is a ground loop problem. Does anyone have an idea what it actually could be?


texts:
Can someone put a name to this DC-coupled low pass filter topology?

To be clear, it's just what this topology is called that I'm after - in the same vein as "A Sallen-Key filter" or "A State Variable filter" but, obviously, not those in particular.

For the curious, the component values given are for a nominal 10 Hz (8.84 Hz in fact) and the rolloff is 3rd order (18 dB/octave).


texts: Kind of a novice question but I wanted to check if I am right about something. I like the convenience of the UDN2981 source driver to provide switched power to for multiple loads. However, I would like to drive loads that requires about 1.5x higher amperage than the specified limit of the chip. Would it be OK to physically stack two of these chips on top of each other to double the current draw capacity that I am able to deliver? I have verified that it seems to work, but I am looking for some sage advice as to whether this is truly OK to do.


texts:
Metal. Length is 5/8", pitch is 0.1". Ruler is centimetres.
This thing is really useful because you can plug it into breadboard and attach a probe clip to the square tab and the connection is extremely secure. It can also be used to bridge two rows directly next to each other.
Unfortunately I only have one and I would like to buy some more.
I think I originally found it in some old computer hardware where it was used as a configuration jumper. Instead of the usual way of having pins on the board, this one had a socket and you plugged this thing into it.


texts: Optocoupler: decoupling circuit parts sharing same ground and power line

texts:
Consider a circuit contains a 5V supply that can provide quite high current, say 2A. Now, on one side of the circuit we have some control device, for example microcontoller, on the other - device that uses quite a lot of power, for example a high-voltage device powered with DC-DC boost converter which converts our 5V to 200V. But, our high-voltage device is controlled via 5V line, so technically we can connect it to MCU output pin with a resistor, to limit current consumption.

Our other option, which is actually my question, is to use optocoupler like 4N25M to split MCU and high-voltage device in such manner that the only things they share are 5V line, GND line and the optocoupler device.

Finally, I can now formulate the question - does it make sense to use optocoupler in such a circuit? When saying "make sense" I mean than when I use optocoupler between sides of the circuit that are completely isolated and doesn't use same power source - optocoupler can protect control device of being damaged in case of input pin of high-voltage device suddenly got connected to HV line (in case of damage for example). But, if two sides of our circuit actually shares same power supply, I am not sure if such usage of optocoupler makes sense at all.


texts: LTSpice component attribute editor problem

texts:
I have a problem in LTSpice with calling "component attribute" on both versions IV and XVII.
Normally you should be able to call the component attribute window by pressing Ctrl+RightClick on the component (for example a Diode). Then you can enter the values that are not within LTSpice library.

But sometimes this short-key doesn't work on my computer which is running windows 10 X86. There is also no menu for it.
Does anybody face this problem and knows how can I solve this problem?


texts: Check my first PCB design for errors (simple high power LED circuit)

texts:
I'm designing my first PCB in Eagle. This PCB is for surface mount LEDs (Epistar 1-3W) and has 5 independent channels. There is an input from my driver circuit and an output for daisy-chaining more LED PCBs. I'll use this to provide different light treatments to plant cell cultures growing in bioreactors.

The traces are 1.27mm to accommodate a max current of ~2A (http://www.4pcb.com/trace-width-calculator.html)

Please let me know if there's anything amiss, or any additional considerations for my design. We want to be able to remove and replace LEDs several times, so I may want to modify the pads- please let me know if you have any recommendations.

Edit
Here's the schematic

Notice that I haven't included the driver circuit. Each channel of LEDs has its own driver (see 5 separate VCC and GND lines on the schematic). I've also omitted a bridge that will connect + to GND for each channel on the last PCB in the daisy chain (visible in the schematic but not the board).

Edit 2
Here's my updated design.
Changes:
(1) Adjusted the trace spacing to 20mil (TY Mishyoshi)(2) Added holes under each LED as heatsinks, if this is insufficient I'll move to a 3 layer board with a copper plane (3) increased the size of the pads for the LEDs (4) added 5mm length on each side of the board to facilitate mounting in our bioreactors

Thanks for your input!


texts: -Ve feedback comparator and its threshold values?

texts:
I was trying to analyse and understand the following circuit.

My intention was to calculate the hysteresis of the comparator.

Circuit working: For both compartor input, there will be voltage inputs ranging from 40 mV to 250 mV. This will vary as per the connected circuits and will trigger the output of the comparator either as HIGH or LOW.
I have worked on comparators with one input pin as fixed-reference voltage and other pin as the varying-input voltage.

Comparator Part Number: TS332 comparator from ST.

For me this seems bit new and I was not able to understand the working of the comparator completely.
Basically I am looking for a guide to calculate the upper and lower threshold and finally the hysteresis.

Could someone help me with this.


texts: How to assign value to bidirectional port in verilog?

texts:
I'm trying to use a bidirectional port in Verilog so I can send a receive data through it. My problem is that when I try to assign a value to the port inside a task, but I keep getting an error.

Which is the correct way to assign a value to these type of variables?

My code is the following:

    module test(value,var);

    inout value;
    output var;
    reg var,value;

    task sendValue;
      begin
        var = 1;
        value = 1;
      end
    endtask

   endmodule

and the error that I'm getting is:
** Error: C:/[...]: (vlog-2110) Illegal reference to a net "value".

Thanks.


texts:
I have a small understanding of how to solve limits to infinity for regular rational equations, but I'm unsure of how to apply this to the Z-Transform initial value theorem.

The equation is:
\$ \lim_{z \rightarrow \infty} \frac{10z^{-1}+5z^{-2}}{1-1.2z^{-1}+0.2z^{-2}}   \$

The answer for this is that \$ x(n) = 0 \$, but I'm unsure of how to arrive at that.

I have watched this YouTube video which helps with understanding the general concept, but I'm not sure how to apply this to Z-Transforms.

Any help would be much appreciated.


texts: why white LED has highest Built in potential

texts:
Why Built-in Potential of White,Red,Green and Blue LEDs are in the order:
 $$V_W > V_B > V_G > V_R$$
where $$V_W \implies Built-in \quad Potential \quad of \quad White \quad LED $$

My Approach:
We know: $$\lambda_R>\lambda_G>\lambda_B$$
$$\therefore E_{gR}< E_{gG} < E_{gB} $$ as Band gap Energy (Eg) is inversely proportional to wavelength (lambda) of light

Now how to correlate Buit-in potential of White LED ?? any hints or suggestions please....?


texts: Infrared spotlight project, need x50 resistors. How many ohms what type to use?

texts:
Infrared spotlight project.

I have a PCB BOARD set up for 150x 5mm IR LED
1.5-1.6 forward voltage.
Forward current is 60 mA

150 LED’s are divided into 50 groups (3 LEDs each + 1 resistor)

What ohm resistors are needed for the 50 groups of three LEDs each?
I was thinking of using x2 18350 Ultrafire 3.7v x2= 7.4 volts.

Suggestions on more or less voltage using increments of 3.7.

Using the online resistor LED calculator: for 150 LEDs grouped 3 LEDs + 1 resistor, the answer given was x50 1/2 W 56 Ohm resistor needed.
Being a broke novice I don't want to order and wait for fifty wrong resistors.
Do you think this is a safe bet? To better understand my confusion please refer to item #251216249922 on eBay or look up PCB board for 150 x LED 3 mm or 5 mm. The third photo completed tells a lot.


texts: Sorry to ask such a trivial question but I am a non-engineering student currently writing an essay on Moore's law and I can't seem to find how the items in my title relate.  An in-depth description of each item would be greatly appreciated!  Also if you could please breakdown technical terms, that would be very helpful.  Thank you for helping me out.


texts: Should I use pull up resistors in this configuration?

texts:
I am interfacing a 3.3V FPGA to a 5V DSP. I am using this bidirectional voltage transceiver:
http://www.nxp.com/documents/data_sheet/GTL2000.pdf

In the diagram in page 4 they're using pull up resistors at the high voltage side and they state:

  The processor output can be totem pole or open drain (pull up resistors may be required) and the chipset output can be totem
  pole or open drain (pull up resistors are required to pull the Dn outputs to VCC).

The DSP I'm using is TI TMS320C31 and will be interfaced to the FPGA Cyclone EP1C6Q240C8N.

Should I use pull up resistors on one of the sides or both or I don't even need them?


texts: Trigger relay at different voltages with voltage comparator

texts:
TL;DR - I need help on making a relay with voltage comparator which accepts two reference voltages.
Aim

My project needs to run a Raspberry Pi on solar power. Solar panel will be connected to a power bank which will then be connected to Raspberry Pi.
Challenge

Running on solar means there won't be enough power left in the power bank for the Pi. In this case I will shut it down and turn it back on when there is enough power. This process needs to be automatic since the project will be installed at a remote place.
Since Raspberry Pi doesn't have ability to detect power from the power bank directly I'm planning to install a circuit between Pi and the power bank. I will use a MCP3008 - Analogue to Digital Converter to detect the voltage level of the power bank. The schematic diagram will look like this.

I will run a script to shut down Pi if it detects only 5% of power is left.
Problem

After shutting down Pi, I want to close the circuit between Pi and the power bank completely so I'm planning to use a relay for this. I think Relay with LM393 like this will do the job.
The problem is I want to switch off the relay when the voltage equals to 5% power of the battery and switch it on automatically when the battery reaches 25% of its power. The module I consider can set only one value of voltage.
So is there any way I can set one value of voltage for the relay to switch off and another value for it to switch on?