texts: Arduino Leonardo in Eclipse VID and PID missing?

texts:
Has anyone got the Arduino Leonardo to program in Eclipse?

I have no trouble with the UNO, but it seems the VID and PID settings are missing for the ATmega32u4

../src/USBCore.cpp:78:2: error: ‘USB_VID’ was not declared in this scope
../src/USBCore.cpp:78:2: error: ‘USB_PID’ was not declared in this scope

Googleing around has uncovered a few GIT projects talking about custom make files from the command prompt there there have recently (in the last month) worked out that they need special patches specifically for the Leonardo. All my projects are in Eclipse already, so it would be good to know how to fix this here.

Perhaps there is a simple #define i can just put somewhere?

[edit] I'm on Ubuntu b.t.w. (in an attempt to avoid a big discussion about windows drivers : P)


texts: Optocoupler - Make active low output at active high

texts:
I'm currently working on a project and it consists of amplifying a 5V signal from an Arduino to 24V. I made my circuit and hooked it up to a oscilloscope and it shows that the output of the optocoupler is active low. I just wanted to know if there's a way I can make it active high.

Thanks in advance.


texts: Derivation of an RC Low Pass Filter's Cutoff Frequency

texts: I can't seem to figure out how to derive an RC low pass filter's cutoff frequency. I'm doing so an exercise because I want to find out the cutoff frequency of a more complex low pass filter, because I can't figure out that either. What I really need is a step by step solution for the RC LPF's cutoff frequency. I can write the equation for an RC filters transfer function but I don't understand how to find the magnitude of the transfer function. All the resources I'm finding do not show the steps. They have the transfer function, then show the magnitude of the transfer function on the next line.


texts: Will i be able to generate electricity in the following case?

texts:
The motor shown is an alternating current, single-phase induction motor of the permanent split capacitor (PSC) type. I i power the electromagnet part with an AC supply of 12V to generate a magnetic field, and then rotated faster than its synchronous speed will the motor then generate electricity with power 106 watt as stated on the label of the motor in the figure.

In case 12V is insufficient then how can i find the volt of the current to be supplied to the motor in order to generate the sufficient electromagnetism.


texts: What does it mean when multimeter accuracy is marked as: ±0,03%+10Digit?

texts:
I have a digital multimeter and its accuracy for VDC is marked like this:

  ±0,03%+10Digit

This multimeter has maximum display of 80000. So in the 80 V range it can show for example 79.999V.

0.03% of 80V is 0.024V - that is clear for me. But what does the +10Digit mean?

The device in question in Digitek DT-80000.


texts:
I found two datasheets for the BT136 triac:

Datasheet one

Datasheet two

But those datasheets didn't mention the inner resistance of the triac (or I couldn't find it.)

What's the resistance between pin T1 and T2 of BT136 triac when the gate is activated?

Edit:

I found another datasheet which mentioned the resistance:

If I pull 2 A from the BT136 what the resistance will be? how to calculate it?


texts: I have always found it very easy to design with dual supplies.This circuit uploaded by me is operating in active region because Vec=3V.Mostly in such circuits very negligible base current flows (don't know why).I find this very strange because the base current controls the collector current.On the contrary if I replace the negative battery (on the bottom right) with ground very large base current starts flowing.I can not understand why?


texts: Flat induction cooktop coil reshaping to cylindrical

texts:
Ten years ago I acquired a Salton (ID-1081) induction cooktop featured with some flat 55 mm (I.D.) x 170 mm (O.D.) 21 turns coil made of AWG #12 stranded wire.  Acceptable IH workloads needed to be at least 12 cm (dia.) and capable of attracting magnets.

Assuming my goal is to accomodate a much smaller 12.5 mm (dia.) x 1.0 mm (thick) 17-holes "susceptor" disc (to supply heat for temporary conversion as convective/radiative vectors), I figure the coil must be reshaped as a cylinder of similar inductance, resistance, etc.  Possibly also having to add a flux concentrator made from non-conduction ceramic (like ferrite powder, whatever).

New coil-geometry suggestions only need to allow brief injection of a Heat Charge within seconds without potential for damage, keeping in mind this IH cooktop was rated in the kilowatt range.  Susceptor (SS430?) peak temperature almost reaching the glowing point may be expected but not necessary.

So far I've roughly evaluated the Energy Charge to be around 100 Joules.  Maybe twice, maybe half but I guessed not as far as 5-fold.


texts: combicon connector capacity rated as 300 volt 15 ampere, how much maximum current it can draw for 240 volt and 120 volt AC?

texts:
i have a Combicon connector "2EDGK", its datasheet says its capacity rated as 300 volt 15 ampere AC,  how much maximum current it can draw for 240 volt and 120 volt AC?

300 VOLT X 15 AMP = 4500 VA,

AMPERE RATING FOR 240 V= 4500/240=18.75 (RESISTIVE LOAD)???


texts: What is the difference between a Line Impedance and Charecteristic Impedence?

texts:
I am thinking this from long time.
In case of Digital Circuits,

I know that, whenever a signal is incident on a PCB trace, for example, there may be an AND gate, which just switched output to 1. Then, a signal (or a wave-front) has to travel along trace and it experiences the characteristic impedance. Which is generally given by,

$$
\sqrt{\dfrac{R+j\omega L}{G+j\omega C}}
$$

Also, in case of digital circuits we are more concerned about the rise time (which is actually very very high frequency signal) and not the frequency. Hence, I think, when the the voltage is incident on the PCB trace, we are considering 'Impulse Response' of trace. Correct? Please correct me if I am wrong

Going back to above equation, by adjusting the L & C (i.e., Trace Width and Distance between trace and ground place) I can Regulate the impedance of the line. Since, we want to have the "High Signal Integrity" we would want to maintain the 50 Ohm (or any other pre-defined impedance) through out the line.

Now coming to my real question,
In case of RF (radio frequency), lets say, we have a RF input of 980MHz. Then also we specify the trace impedance, again generally will be 50 ohms. But, in case of RF input, we have the sine wave as input and not the square wave. So, my rise time requirement will not come into picture. (right??). How and why do still we maintain the trace impedance?
If you have any good study material that would be great too!


texts: minimal delay between input and output possible to implement in FPGA

texts:
I am trying to find out how fast can I get the transition of a digital 500MHz signal from FPGA input to it's output. The delay will need to be adjusted, but that's a different task. For now I just need to know if I could make it around 4-8 ns.

FPGA is not chosen yet, probably one from Altera. Need to find a suitable one.


texts: Will these gloves comply with electrical arc flash safety?

texts:
I am beseeching any OSHA, CalOSHA or electrical safety experts out there on this one for a little help. I know this is not strictly electrical engineering but this is the closest Stack to the topic.
Per OSHA regulations an employer is responsible for providing adequate PPE to it's workers. My electrical company is engaged in commercial industrial electrical work in the southwestern united states, mostly california, some nevada and arizona jobs. We work 99.9% with voltages of 480 and below.
NFPA 70E mandates for the PPE category selection method we are generally in category 1 and category 2 situations. in NFPA 70E table 130.7(c)(15)(a) there's a note stating if you're working on equipment at 600V or less and protected by upstream OCPDs of 200Amps or less you can reduce the category by 1, but not below category 1. Category 1 calls for leather gloves for your PPE for hand protection.
(Sorry I am getting to the question!)
H o w e v e r.
NFPA 70E is reportedly a consensus standard and is not mandatorily in force universally. Obviously OSHA laws being federal laws ARE.
My electricians (and having been an electrician myself for a few years back in the aughts, I totally understand) assert that leather gloves, even when fitted, suck for manual dexterity and in some cases present more of a hazard as you are much more likely to drop things, lose grip, have false grip, etc.
So bottom line. I want something my electricians will actually use and not remove the minute a production or safety manager walks away (before anyone says, well, your electricians suck, they're hacks, fire them, etc. look, I get it, but that's just not the way the world works. Maybe at your plant, or distribution facility, etc. it is, but for most mid size electrical companies, it's the wild west, good luck trying to get a local food storage warehouse to do an arc flash hazard analysis so we can be in compliance) Still though, safety is important to me and I want my guys protected. So if leather gloves are a requirement of a not federally enforced standard (70E) can I possibly get away with these:
Even though they are not leather, it seems they might actually exceed the cal/sq" requirements and possibly provide better protection than leather. I'm not myself an EE, though, so I could use advice.
option 1
or these:
option 2
Thoughts/advice from anyone with expertise or experience is welcome. Thanks in advance.


texts:
I am studying control systems and I am studying the topic of Singular Value Decomposition(SVD).

I have found a transfer matrix of a systemm, and computed its DC gain. Then I have performed the syngular value decomposition, and found that it is:

\$V=\begin{bmatrix}
0.1316  & 0.9913 & 0\\
 0&  0& 1\\
 0.9913& -0.1316 & 0
\end{bmatrix}\$

\$S=\begin{bmatrix}
8.7936 &  0& 0 & 0\\
 0&   0.8200&  0& 0\\
 0& 0 & 0 & 0
\end{bmatrix}\$

\$U=\begin{bmatrix}
0.5786 &  0.4065&  0& 0.707\\
 -0.1127& 0.1605 &  0.9806& 0\\
-0.5636 &  0.8024& -0.1961 & -0.0000\\
 -0.5786&  -0.4065&  -0.0000& 0.7071
\end{bmatrix}\$

Now, I am not sure I have understand what does this implies for a control system.

So far, I have understood that I the matrix \$V\$ is the matrix of the input directions, so if I have an input, it can have in this case three directions, which are the three columns of the matrix $V$. Then, the input in the chosen direction gets amplified byt the singular value which corresponds to that direction.

In my case, I don't understand few things. First of all, I see that the last two columns of the singular value matrix are zeros, what does this mean? And also I can see that inputs directions are three, while the output directions are \$4\$, and I have only two singular values, since one is zero, so I have at most three singular values.

What does it means? Can somebody help me clarify this situation?


texts: What is the explanation with shorting vcc and gnd to power up the whole circuit in a breadboard?

texts:
I was building a logic circuitry that performs 8 bit multiplier 16 bit divider using decoders as finite state machine in breadboards. the circuit is a bit large and i wonder why grounds or low voltage doesn't spread to other part of the circuitry or ICs. When test with logic probe, the reading has noise and most of the time, there will be no reading.

I come to a point to try to short VCC and ground. This solves everything. The circuitry has grounds to the whole circuit or to all ICs. And also, LEDs have high brightness.

My question is in large circuits, why does ground not spread evenly to other ICs or other parts of the circuit? and What is the explanation of the ground and VCC shorting solve this problem?


texts: is a uA current FET or BJT circuit design possible?

texts:
I'm working on a battery powered circuit that is triggering an interrupt on an ic with an internal pull-up. The resistor value and normally closed switch can not be changed. The quiescent current is way too high for our application 200uA. Our target is 0-6uA.

Is there a FET/BJT circuit that could be added between the switch and the ic that could be designed to achieve the target current?

Any ideas?
Thanks

**EDIT comment

**I was using the NC switch to represent a physical characteristic of our device, now that I think about it it's more like a fuse. ie. We are trying to detect when the fuse is blown.


texts:
I am writing a controller for a low power/mobile DDR module on my FPGA. To allow debugging, I use a functional model written in Verilog. In it, the setup and hold time for some signal is set to 1.5 ns. If I understand everything correctly, this means that the signal can not change 'within' 1.5 ns of a rising clock edge.

However, the RTL that I've written does not include timing, so the signal appears to change instantly, yielding hold time warnings.

On the one hand, I am not too concerned; I'm only getting warnings, and I think that during a project for my university, we were told to simply ignore these errors.

On the other, I don't like to ignore warnings. The manufacturer would not have implemented these warnings if they have no purpose. Since Xilinx ISE is able to check timing constraints, I feel like it should be possible to route and map my design, and use the generated timings somehow (but maybe I'm making things too simple here).

I'm sure there are more people with the same problem. What is the proper way to deal with these warnings?

Edit: On this page, I found some more information. You can generate a post-map or post-place-and-route simulation model. I suspect this includes the timings. However, it seems only modelsim can actually perform the simulation.

Clarification: Ideally, I would be able to synthesize (or at least get as far in the process of generating the layout as possible) my part of the design (I have the RTL and I have specified the board, so I think this should be possible), then combine it in a testbench with the functional model to test if my design has the proper timing delays. However, I can't make this work in Xilinx ISE 14.7.


texts: Need help finding a proper replacement for a burnt resistor

texts:
I need to replace a burnt resistor, but I have trouble finding a proper replacement.
The dead resistor has 5 color bands on it:
Brown - Black - Brown - Silver - Yellow

which can result in a value of 1.01 ohm 5% (assuming that the yellow color band is actually golden).
After reading some forum threads about repairing the same PCB, I know that the resistor should be flameproof, wire wound and anti surge, which seem to be logical.
What I do not understand is, why the proposed replacement should be 100 ohms (3W).
Here is a photo of the dead resistor:

I do not have the wiring diagram of the PCB and I can't find it on the internet. So I am stuck.
I hope, somebody can shed some light on my problem.
EDIT:
So, guys, I wanted to thank you all for your hints! I kind of combined them into one answer for me and it helped me a lot.
The most valuable hint I got from @Justme: "Yellow is not a valid band color. It has to mean something else". This seemed very plausible to me. So the resistor value had to be 100 ohms 10% (Brown - Black - Brown - Silver).
I ordered some 100 ohms +/- 10% 3W fusible resistors, like suggested by @Spehro Pefhany and replaced the burnt one. (I also replaced the burnt TNY264GN chip, which I didn't mention in my question).
My repair job went well and now the device (my Siemens dishwasher) is working again. The resistor doesn't get hot etc., which is also a good sign.


texts: Circuit analysis with dependent current source and tricky voltage source

texts:
I've been wasting my time on this problem and I did get really close to a solution which took a long time but still wasnt able to get the solution.
I was wonderting that I might approach this problem in the wrong way which is the main thing that bothers me.
The question was to find the voltage Vb I tried both mesh and node analysis also tried super/node/mesh.
below is as far as I got to a solution.
I would be glad if someone can enlighten me on how to approach this kind of question as I'me having some trouble with those.
Thanks.


texts: Can an electromagnet sense magnetic load on it?

texts: Say I have an electromagnet, and I put a permanent magnet next to it, the fields repelling. Is there a circuit that can be created that will detect the magnetic load on the electromagnet produced by the permanent magnet's magnetic field in the form of increased or decreased electrical activity within the electromagnet?


texts: Delay circuit with capacitor and transistor doesn't work as expected

texts:
I made the following delay circuit. According to the simulation, it should take in the order of seconds for the relay to switch. Instead what I find (even by varying the resistance of the second stage) is that the relay switches on in about 100ms. In particular the tension on the capacitor C2 rises very quickly and in C3 almost instantaneously. Is there something I'm doing obviously wrong?

My input is 60Hz 12Vrsm and the 5ohm resistor is simulating a resettable fuse for 0.1A. The transistors (BC337-25) are rated for 45V C-E and the diode is a schottky with a 0.6V drop and rated for 40V breakdown.


texts: Determining direction from an inductive joystick

texts:
I'm trying to understand and (eventually) repurpose an old inductive joystick, but I'm not sure how the micro controller determines which direction the stick was pushed in?

There are 4 coils on the PCB and one on the joystick. The pcb coils are paired together by axis with an ADC input connected at either end, while the joystick coil is controlled by a timer output. The MCU is an atmega8 running at 8MHz.
Experimentally driving the joystick coil at 20kHz, 5kHz, and 2.5kHz seems to work. It then looks like the pcb coils oppose each other normally, so when the joystick moves towards one the amplitude from that coil increases while the other decreases.

My guess was that I could pick the direction by checking the phase, but doing so seems nontrivial with the existing MCU (slow!) and I'm not sure how to figure the phase change out from the two sets of ADC results. Is there another way that I am missing, or some trick to make this feasible?

The joystick coil is hooked up roughly like this:

simulate this circuit – Schematic created using CircuitLab

Remaining 4 coils are grouped by axis. The last pin of the transistor doesn't appear to be connected so I'm assuming it is acting as a diode?

simulate this circuit

I have a basic multimeter and can log ADC results and push them through the serial port on the board. Below is a example waveform collected from the MCU, split into 100-sample chunks. The smaller oscillations I think is from driving the joystick coil at roughly 2.5kHz, while the large amplitude apparently higher frequency oscillations appeared when moving the joystick up or down.


texts:
Relevant Datasheets:

AS431 Voltage Reference
INA126 Instrumentation Amplifier

I am designing a circuit which will amplify a few millivolt input (~+/-10mV full range) to a few volts (~0-8V output, centered at 4V). I have spec'd out an instrumentation amplifier with a voltage reference to give the desired center voltage, and now am designing the voltage reference part.

The option I am considering is the AS431 shunt voltage reference. I like the simplicity, but I am worried about output impedance as the INA126 specifies(ish) that ~8ohm output impedance will reduce the CMRR to ~80dB, and to prevent the AS431 from getting fried, I would prefer to limit current to the AS431 to ~10mA.

Reference voltage regulator circuit (taken from the datasheet):

Vin=8V, thus the desired R3 is 4V/10mA = 400 ohms (assuming R1+R2 >> R3). If the output impedance is 400 ohms, the CMRR is completely toast. However, being a voltage reference I don't know if the output impedance is necessarily the same as the input impedance. Even playing it fast and loose by drawing ~100mA through the AS431 requires ~40ohm shunt resistor.

Would I have to add something like a voltage follower to the output to get the desired low-impedance reference the INA126 needs? Or is there something I'm not quite understanding about how shunt regulators/voltage references work?

If I do need the voltage follower after the voltage reference circuit, why would I even bother using the shunt reference in the first place? I could just as easily feed the voltage-divided reference directly into the voltage follower to get a low-impedance reference output.


texts: Pump does not get enough current via MOSFET

texts:
I am trying to build the v4.3 circuit described here: Will this schematic work?

I am building just one branch out of the decoder IC to test on a breadboard. Component info is as follows:

The optocoupler is PC817 i.s.o TLP621;
The MOSFET is IRF630B;
The flyback diode is 6A4;
The resistor between MOSFET gate and ground is 5.2K;
The peak power rating of the pump is 2.7A @12V.

Now when power is on, RasPi is up and the input to the decoder is set correctly, the pump does not work.

I tried the following to troubleshoot,

Connected the pump directly to 12V input, it works. Connected a multimeter in series and found the current draw to be approx 3A to start and then dropping down to 1.8A;
Connected an LED via a suitable resistor across the output side of the optocoupler (no mosfet/pump) and it turns on and off depending upon logic input to the decoder;
Removed LED and measured the voltage across the output side of the opto-coupler to be ~12V;
Added the mosfet and measured the voltage across the drain and source with correct logic input to decoder. This measured ~11-12V;
Added pump (w/o flyback diode). Now with correct logic input to decoder, it does not work;
Connected a multimeter (in current reading mode) in series between the cathode of the pump and drain. It measures only 0.63A;
Replace the pump with LED and proper resistor and enable the decoder, the LED lights up.

It appears to me that connecting the pump via the MOSFET somehow impedes the current flow to a great extent even when it is biased according to specs.

I thought that the MOSFET in question is a voltage controlled device. So when a proper \$V_{gs}\$ is applied, it should simply conduct the current required by the load.

Why does it conduct only 0.63A when the starting current requirement is around 3A? Am I missing anything?


texts: Capacitor polarity confusion in a circuit

texts:
I was reading about opamp integrator concept in a text as such:

I marked the terminals of caps as a and b.
Above formula assumes the b terminal as being the positive end I guess.

But regarding the direction of I2, can't we say that the positive terminal of the capacitor is a?

But then if it the positive terminal is a, then it is connected to the ground. What is the + and - ends of the capacitors in the above figure?

I know it is basic circuit theory but somehow I'm confused at this point.

Isn't there only one option of the polarity of a cap at a moment for a given current direction across it?

EDIT:

Besides these, I also do not get why in sim for the inverting input (point X) the voltage is not zero for 10 secs of time duration.
According to op amp theory Vx must be around zero but it is around 1V here:


texts:
I have read several articles which say that the CPU has the ALU (and other small specific execution units), Control Unit and the Registers and well other buffers/pipelines, internal buses etc.

The Control unit:

  The control unit implements the architecture of the CPU. It performs
  the tasks of fetching, decoding, managing execution and then storing
  results.

Studying pipeline concept, and what I understand is that at least two steps:

1. Fetch,Decode--->CONTROL UNIT

2. Execute-------->ALU and OTHER EXECUTE UNITS

Both steps PERFORMED IN PARALLEL. That is, while the CPU is executing an instruction, at that same time another is being fetched and decoded.

Am I correct in assuming the above? Or do the Control unit and Execution unit work one after the other like some kind of switching between clock cycles?


texts: E-Mag Biot-Savart law (line current - Magnetic field)

texts:
I am taking an electro-magnetics course and I have these problem.

When I found the alphas values (\$\alpha_1 = \frac{3}{\sqrt{13}}\$ and \$\alpha_2 = 0\$ because of the infinity line).

The equation says that
$$cos(\alpha_2) - cos(\alpha_1)$$
which make it
$$1-\frac{3}{\sqrt{13}}$$

The problem is: in the solution 145m which could be found with \$1+\frac{3}{\sqrt{13}}\$, how it could be \$+\$?


texts: What type of axial capacitor is silver with transparent ends

texts:
I am reorganising my hobby electronics workplace and have found a box of axial leaded capacitors that all look the same, apart from their size and marking. They are silver with transparent ends, no hint of maker or obvious type number; the biggest, about 10mm long body, 4mm diameter, is marked 470J 125YS.

I am trying to reduce by 3/4 the amount of stuff I have hoarded over the years, and in the process my capacitance meter is still somewhere under the heap to be sorted, so I can't determine the capacitance of most of them yet.

My question is: what type of capacitor are they, and are they cheap enough to dump, or valuable and difficult to replace?


texts: Transformer Sizing with Mixed Loads (Three-Phase & Single-Phase)

texts:
I am trying to size/validate the rating on the medium voltage main transformer for an industrial plant. For some reason I can't find many resources that indicate how to properly do this when you have mixed loads. Mixed loads meaning three-phase three pole, single-phase two pole, and single-phase one pole loads.

Suppose, for example, the transformer feeds a 3\$\phi\$, 4W panelboard with the following loads:

(2) -- 100 A, 600 VAC, 3\$\phi\$, 3P
(2) -- 50 A, 600 VAC, 1\$\phi\$, 2P
(2) -- 15 A, 347 VAC, 1\$\phi\$, 1P

What is the proper way of determining the supply transformer rating?

My thoughts/work:

I could simply calculate the apparent power using both the three-phase and single-phase formulas and add them together. Resulting in:

$$ S_{TOTAL} = \sqrt3 * 600 V_{LL} * 200 A + 600 V_{LL} * 100 A + 347 V_{LN} * 30 A = 278 kVA$$

I could also recognize that the legs need to be distributed in the panelboard -- the three-phase load will be added to all phases, but single-phase loads can't be split up evenly. Resulting in:

$$ S_{TOT} =99.3 kVA * 3 = 297.9 kVA $$

Neither of these items take into account standard transformer sizing, derating, power factor, demand factor, or allowable loading.


texts: How to lower the temperature limit of a regular NTC thermistor

texts:
I am looking to make a simple circuit where i want to measure a freezer's temperature at -80 C. The problem is that most NTC thermistors i see have a low range of about -40 C. Is there a trick in designing the voltage divider to capture only low temperatures. I would accept an error of +-10C.

I would like to use a cheap thermistor if possible


texts:
I'm trying to amplify a 20mV ptp signal to something around 1V ptp. I intent on only doing this in one stage and require the amplifier to be very low power consumption (3.3V supply max 1mA for entire amplifier). I'm trying to choose a bias point to operate the device at that will give a low enough power consumption and still give me the optimal gain I'm looking for. Drawing a load line on the BC846 NPN BJT I get a Q point that is very hard to achieve:

I was wondering what characteristics I am looking for in a BJT that would give a lower current bias point.

My current amp design:

The bandwidth is only 100kHz.

Source impedance is ~5k purely real and load impedance is 100k real.


texts: How can I link a component's current to variable resistor value in LTSPice?

texts:
In LTSpice I want to implement an LDR resistor which changes due to the current passing through an LED.

I want the current through the LED (D1) to vary LDR. I want to use the LED's current in an equation and link it to LDR's resistance (ohm).

How is that possible?

edit:


texts: How to boost a Power Bank's maximum output voltage?

texts:
I have an Anker ~27Ah Power Bank which has 3 × (5v , 3A) power output.

Is it possible to connect the outputs in series and get 10v or 15v output with a current flow of 3A?


texts:
So I have this node voltage equation problem.  Seems really easy, actually.

simulate this circuit – Schematic created using CircuitLab

In fact, this appears to be only one equation, barring constants.
$$\frac{1}{110}v_{12}+(2)\frac{20}{10}+\frac{1}{100}v_1=0$$ with the fairly obvious addition of \$v_2=20\$.

This works out to be \$v_1=200\space\mathrm{v}\$.

However, the book says the answer is 219 volts.  What is the error in my approach?


texts: MCP23017 - detecting state of IOCON.BANK bit after MCU reset

texts:
Datasheet for reference here.

The port registers of the MCP23017 I2C I/O expander can be configured in two ways using the IOCON.BANK bit as follows:

  If BANK = 0, the A/B registers are paired. For
  example, IODIRA is mapped to address 00h and
  IODIRB is mapped to the next address (address
  01h). The mapping for all registers is from 00h
  -15h.

  If BANK = 1, the registers associated with each
  port are segregated. Registers associated with
  PORTA are mapped from address 00h - 0Ah and
  registers associated with PORTB are mapped
  from 10h - 1Ah.

By changing the IOCON.BANK bit, the address of the IOCON register itself changes, see table 3-4, 3-5 in the datasheet.

So, in the case of a MCU reset, how do you determine the state of IOCON.BANK without resetting the MCP23017 so that any peripherals attached to the MCP23017 are unaffected?


texts: Chaining limit for shift registers in large led matrix

texts:
I am thinking of trying to build a large led matrix in a way that is both modular and scalable (maybe up to around 100x100, or 500x16).

My thought is to make a single 8x8 module that I can make a few at a time as budget allows. Each module will simply pass its rows and columns through to the adjacent modules. I will use shift registers (595 or similar) on the end modules only to drive the columns and the common cathodes on the rows.

Is there a limit to how many shift registers I can chain in a row, or will they pretty much extend indefinitely? Are there any limits other than the time required to shift out an increasing number of bytes? As the number of columns increases the time to shift out that many bytes increases, so I could imagine needing a heavier microcontroller to shift out larger displays at higher refresh rates. I am not too worried about that. My initial design will use an arduino, but I can move to a heavier 32 bit mcu as I need it.

My main concern is current. If I only am driving one row at a time, does it matter how many rows I have connected to each column? Do I need to adjust my resistor values as the matrix scales up, or add more resistors per column? Does my power supply need to get bigger the more leds I add?


texts:
I got the dimension of the 10 DOF IMU model D on the internet. I wonder what is the dimension from the left to the center of the hole of the header pin. Besides that, for this type of header pin, the radius is 1.02mm, isn't it?
I tried to look for other pictures, but this is the best one that I could find.
Thank  you so much for your help!


texts: Signal processing, signal recovering with lowpass filter

texts:
Here's problem (Lathi):

a. \$ x(t) = 5 sinc^2 (5 \pi t) + cos (20 \pi t) \$

Bandwidth = \$ 20 \pi \$

\$ f_s = 10 Hz, w_s = 20 \pi \$

Signal can be reconstructed from samples if \$ w_s > 2 w_{bandwidth} \$

Here's solution.

I was wondering, why is it for part B signal can be reconstructed from samples? \$ w_s \$ is equal to bandwidth of the original signal, so original signal shouldn't be reconstructed because \$w_s\$ should be greater than the bandwidth of original signal, no?

And why is that in part C signal can be reconstructed but without sine component?


texts: To pass a certain frequency, you can either have a resonant LC or a bandpass filter made from 2 capacitors and 2 resistors (a high pass and low pass filter put back to back. What is the difference between these two circuits, and is there an advantage of one over the other?


texts: modem free high base AM data transfer possible?

texts:
not a very experienced EE, but I was thinking about a system for high speed data transfer,
and it is fairly simple conceptually, so I imagine that there must be serious flaws with the method,
because to my knowledge it is not implemented, or at least not widespread. I apologize in advance for
my ignorance of the subject matter (I'm just starting my learning).

The way I understand it, binary signals enclosed in a carrier wave are modulated/demodulated through a modem.
I understand why this was done in the past - processors weren't that hardcore, and the hardware can only
understand binary. I guess I just don't understand why it is still done this way.

If we modulate the amplitude of a wave (I think by providing the oscillator different levels of current),
can we not sample this wave with some sort of analog to digital converter and process it on the CPU?

If this is possible, why stick to base 2? If we can have a unique value for each measurable amplitude,
data transfer rates would skyrocket. Imagine transferring data with base 1024, or even higher. If we
could accurately sample the wave (each oscillation), I don't see why the rate of transfer could be equal
to the frequency of the wave times base divided by 2 bits per second (this is probably not correct mathing).

If we have a processor running in the gigahertz, and a signal in the low megahertz, it seems feasible that
the processor would be able to sample and translate the data to base 2 (possibly sending to another core
for translation). This way, the data rate would be limited by the processor (faster processors would lead
to the utilization of higher frequencies for transfer).

Limiting factors that I can think of are how fast the current to the oscillator can be changed (for TX),
how fast the analog to digital conversion can be done (read that accurate sampling is possible into the
hundreds of megahertz), and the range of measurable amplitudes.

I'm aware that this question probably contains an unusal amount of stupidity, but I want to build this
system and I'm wondering why I shouldn't. There has to be something major that I am missing here. What could it be? Thanks.


texts: RC snubber on mains connected bridge rectifier

texts:
I am designing a SMPS (90-230V) that has a bridge rectifier connected to the mains (of course after x2 capacitor and common mode choke).

We need this SMPS not to pollute with noise the mains , so we are thinking about using RC snubbers across each diode (in the bridge rectifier) . The diodes have a capacitance of 70pf.

We are thinking about choosing the C (of RC snubber) of about 140pf. My question is...at what voltage rating should I chose this capacitor ? Should it be X2 rated ? Can we use ceramic or needs to be film.


texts: Inverter turns off on computer with 18650

texts: I have a battery setup of 3s4p (12V) with the batter of 20A high drain, it has bms with it. It works perfectly if i put it on my inverter (2500w, 12v) and power laptops or monitor screen. But when i use it for computer or vacuum, the inverter doesnt seem to handle it. Am i missing something? could it be my battery cant handle the surge power?


texts: Mid 80's DIP8 and DIP14 Chip Identification

texts:
Working on a mid-80's engine control unit, I have spent the better part of two days finding datasheets/pinouts for two mystery chips. I originally thought they were 4000 series logic chips, but no such numbers exist.
The unit is from a gen and appears to be a Ford EEC-IV controlling throttle body injection, on an accessory board labeled "FBC", for "Feedback Carburetor"
The were apparently made by Signetics (now NXP) - due to the S on the chip.
However, I cannot find any datasheet for either the 4501 or 4514 part:

The full markings are:
IC1: 4501 8408 S 005BB
IC3: 700002BB 8422 S 4514
I was able to determine that:
IC1 has +5V on Pin 3 & GND on pin 12
IC3 has +5V on Pin 4 & GND on pin 8
I suspect that 8408 / 8422 are date codes. IC3 smells like some sort of OpAmp with nonstandard pinout!?
For what it's worth, here are schematics I drew of the periphery around them:

Any hints, however silly, are appreciated!
UPDATE After getting my hands on some high resolution images of other boards, some of them have:
IC3 = S4501 = S4017 = RCA 340; but they are all marked (70)005BB
IC1 = S4514 = S4513 = S3501; but they are all marked 700002BB
It appears that this is the "true" model number of an ASIC possibly. I have not found any cross mappings of internal part numbers to real part numbers as for the other board yet.


texts:
I'm using this connector in designing rgb LED strip for Christmas decoration lights string. I need fifty more of this but don't know how to order it because I don't know what it is called.

Thirty cm of rgb strip is inserted inside polyurethene tube which is cut to the same length. The second problem is the 30cm tube is arced. Is there any easy way to straighten these? The purpose of the tube is to stiff the strip and seal it from water.

Pls help.


texts: How can I design a clean system using 120 v generator, battery back UPS, and a reversed transformer to get a clean stable 220v with 30 amps?

texts:
This is a old question about design and I must of asked the wrong question. so here goes.
Do I even need the Battery backup in this design and how does it affect the volts and total amps? looking to get 30 amps or better.
Below is what was discussed previously.
I have a Westinghouse 3600W 30 ampere 120 volt generator.
Can I run it through a battery backup UPS to keep the volts stable, then use an HS1F2AS isolation transformer wired backwards to get 240 volts to the breaker box?
This would allow me to run the 240V well pump and maybe the 240V hot water heater.
I am trying to use what I materials I have on hand.
The manufacturer said the transformer can be wired backwards, but I haven't got a clue how to. I'm going to add a breaker and use an interlock to stop the generator from powering the utility lines to the house.
If any one has an idea, please tell me.

This is a picture of the transformer nameplate:


texts: How to calculate voltage divider transistor bias?

texts:
So I've been trying to learn how to calculate transistor bias, but I can't seem to find any appropriate equations. Let's say I have this (right) circuit which I can transform to the left circuit.

I know that Ucc = 10V, therefore Uce = 5V.

I chose Ic=Ie = 100mA and h21 = 100.

I can calculate Ib = 1mA (Ic/h21).

I want Ube to be 0,7V (so transistor openes).

Now if I want to get value of Uc (Rc voltage drop) to calculate Rc I would need
Uc = Uce - Ue  but I do not know Ue.
If I try to calculate Ue = Ic * Re that doesn't work since I don't know Re.

Ue = Ub2 - Ube is the last option then.

Now, Ub2 = Rb2 * (Ib1 - Ib) - Ib1 is current at the beggining of the branch, Ib current that went into base.

The only thing left for me is to transform the 2 resistors into one, getting their resistance value together.

If I do that, I can get another equation Rb = Rb1 * Rb2 / Rb1 + Rb2 but that's it, I can't get those 2 out of it.

I heard that approximately Ue = 0,2 * Ucc and approximately Rb2 = Ube / 10 * Ib

but I would like to know how to properly calculate it with what I've been given, or how to get these approximations or at least where did these numbers came from so I can understand it and not just throw random values in.

I spent about 3 hours looking for answer, but I had no luck.


texts: How to express a function in terms of singularity functions?

texts:
This is the question from the domain of the operational calculus related to circuit analysis. Here is the graph of the sawtooth function:

It is asked to represent this function as a combination of singularity functions: unit step, unit impulse or unit ramp function. Also, the author postulates that this function is the result of the multiplication of ramp and gate function and gives the following solution:

I am particularly perplexed by this transformation:

5tu(t-2) = 5(t-2+2)u(t-2) = 5(t-2)u(t-2) - 10u(t-2).

What is the logic behind?

And more general question. The author proposes another much simpler for the understanding method, namely express the given function as a sum of singularity functions: ramp (0 < t < 2), ramp (t > 2) and unit step (t = 2). Also, which method is normally used by electrical engineers?


texts:
I recently bought a pure sine wave 2kV portable generator to use for camping. In the manual it states that the generator should be grounded to actual earth through a metal stake and then attached to an earthing bolt on the generator at all times.

I’ve confirmed that there is low DC resistance between the earth bolt and mains IEC earth plug outlet on the generator using a multimeter (no surprises there).

I then measured the DC resistance  between the IEC earth pin and neutral on the outlet of the generator and got an open circuit. I am not 100% certain that this is a conclusive test that determines that galvanic isolation exists between the earth and neutral pin on the generator. However let’s assume there is isolation between the neutral and earth for now.

If I can 100% prove that galvanic isolation exists between the neutral and the earth on the outlet of the portable generator then am I right in saying there is absolutely no point in earthing the generator with a stake into the ground from a safety point of view?

Even if the neutral was bonded to the earth pin of the generator and an active wire came loose and hit the case on a faulty connected appliance, the current would have a low resistance path through the earth wiring back to the generators neutral and not through the person holding the faulty appliance.

Not sure if I’m missing something but I don’t understand why you would want to ground a portable generator to actual earth using a stake in any situation. I don’t even understand why the main power distribution networks ground the service line transformers to actual earth which means we then need RCD's, seems like we are making it less safe from a safety point of view but this is a topic for another discussion.


texts:
I have built a circuit of a battery charger here. Here is the circuit in the original project:

However, it doesn't seem to work. The output I measure at the battery charging clips is only 1.2 V or so while the LED2 is on. Now I don't want to bother people here with all my questions, but it often helps me to think out loud explaining what I do in order to find the problem.

I will also try to use the circuit sketch tool here to see if it can predict the voltages that I should measure at the various points in the circuit. But I see it can't simulate SCRs anyway, so that didn't work.

I do not have really good equipment. No oscilloscope. I have a cheap analog and a digital multimeter. The trouble starts with the transformer. It is rated 15 V and yet I only get 14.3 V to start with. But I don't remember exactly if multimeter readings from AC are always low? Plugged into the power outlet directly I get a reading of only 210 V. I remember in Germany as a young hobbyist I always measured higher, like 230 V AC and I even knew the reason for this. Like the difference between V ss (as they call it there, from apex to apex of the sine wave) vs. the power integral, something like that. Anyway, I don't remember measuring less.

So, let me suppose both my meters are bad. Both measure only 210 V. On a 5 V TTL circuit powered by a USB phone charger I measure 5.1 V, but that's DC. Maybe only the AC measurements are off? If I apply a correction factor of 4.8%, then I get 220 V and 15 V on the transformer output.  Now after the rectifier bridge I get only 12.3 V. That is super strange, as I remember that after rectifying the readings were usually higher than the AC reading. But I'm not sure. Clearly if the output was just 12.3 V there is no way I can drive a battery charger from this.

But be that as it may, next my potential difference over the LEDs are 1.9 V LED1, 1.6 V LED2. So I should get 12.3-1.6  = 10.7 V over all of R5 and SCR2 to ground. That is what I get. OK.

But now, the voltage at the SCR2 over A to K is only 1.27 V. That is as if it was open. So what's the potential at it's gate? Only 0.62 V! And this is independent of the potentiometer.

The output at SCR1's K is only 1.2 V. Given the resistors R2 1.5 kOhm and VR1 10 kOhm the vast majority should fall over the VR1, and it definitely should vary depending on the setting of VR1. But it doesn't vary much. It is between 1.09 V and 1.16 V. Given that R2 is 1.5 kOhm, what is the resistance of VR1 for a voltage over VR1 U1 between 1.09 and 1.16 V? It is VR1 = U1 / (U - U1) * R2 = 1.09V / (1.2 V - 1.09 V) * 1.5 kOhm = 14.8 kOhm, and in the other extreme over 400 kOhm. That is definitely fishy. But still, why would the Zener diode let anything through?

I suppose I need an oscilloscope to figure this out. I have an Arduino here, but another project to fix my first project?

I suppose there is something wrong either with the potentiometer or with the Zener diode. Perhaps everything is working fine and only because the battery is not connected does the system shut down entirely? If current was passing through the battery (I don't have a battery to test, I need this thing to work because I get back to my battery at a remote place where I can not buy any electronic parts), then would the Zener diode not trigger the shut off?

To summarize the findings to this point:

it looks like SCR2 is open, even though I measure only 0.6 V on its gate there is only 1.12 V on the gate of SCR1.
I checked all resistors, including the VR1, they are according to specifications.
so this means indeed that the ZD1 triggers because the maximum voltage is on the cathode of SCR1.
but if that was the case, I should be able to down regulate VR1 setting it almost to ground, so then the ZD1 should definitely not trigger

I cannot see why there should remain a 0.6 V potential measurable on the SCR2's gate if VR1 is all the way shorted to ground? So what could be wrong?


texts: AVR programmer with serial to USB converter

texts:
I am struggling with making a usb programmer for Atmega. I couldn't get my hands on a proper FT232L or something like that, but I did manage to find a serial to usb converter like this. This gets detected like a normal com port and is able to make work modems and printers. Will that do serial programming? There are serial programmers around which I have seen, work with ponyser as the programmer in the makefile. How do I make one?

Edit
Through lsusb I have found out that the converter has a pl2303 inside (compatible with ft232r) so how do I do the programming now?


texts: Linear power supply + zero-crossing detection on transformer secondary

texts:
Having read this comment, I'm a bit concerned about whether one of my projects is going to work:

simulate this circuit – Schematic created using CircuitLab

The comparator is also inside the uC, but shown explicitly for clarity.

The intent of this question appears to be an exact duplicate, but its only answer completely misses what I think is a critical point: The transformer is (almost) completely unloaded at the time that I want the ZCD pulse.

I can understand that having both linear and reactive components, considering the transformer and the load together, can cause a load-dependent phase-shift, and that's what the other answer was about.  But in my case, and in the case of the other question, the transformer becomes unloaded for all except the peaks, and we want to sense the zeros.  Given that detail, is there still a phase-shift to worry about between the primary zero-crossing and the secondary one?


texts:
I have created a ROM megafunction using the MegaWizard plug-in Manager. This created a new file which I named rom.vhd.

My code:

library ieee;
use ieee.std_logic_1164.all;

entity first is
port(
PC: in STD_LOGIC_VECTOR(7 downto 0);
data : out STD_LOGIC_VECTOR(7 downto 0);
clock : in STD_LOGIC
);
end first;

architecture behavioral of first is
begin

rom_inst : rom PORT MAP (PC, clock, data);

end behavioral;

I get the error: Error (10482): VHDL error at first.vhd(15): object "rom" is used but not declared

How can I fix this problem so VHDL recognizes that I have a ROM in my external file named ROM.vhd?


texts: Using a Keyboard in a 556 Stepped Tone Generator

texts: I'm in the process of making a simple stepped tone generator using the 556 timer, but I want to be able to have different resistors to change the pitch of the tone I get out. I think it would be really nifty to repurpose an old computer keyboard to act as the switch between these different resistors to cause different pitches, but I'm not sure where to start when it comes to getting the computer to bridge between different resistances or traces.


texts: I am trying to learn MQTT technology. What I understand so far, is that MQTT is based on a 'Broker' that does the 'Publish and Subscribe' of messages and topics. I wonder if it's another name for 'Server' in common terms? If it's like that, then why do they need to coin a new term for a server specially for the MQTT protocol? And in the server-client case, the remote nodes are called 'clients'. What specific term is used for MQTT client nodes?


texts:
I have a drone, but one of the cables connecting the battery to the circuit detached and I took it apart so I could have better acces to the circuit board. I know where the cable goes but my problem is I do not know how to reattach it to the circuit board. The cable and the area of attachment are both flat/there are no hoops or anything to tie the conducting of the cable around. I have tried to find a way to do it but I do not want to damage it by doing something I'm not sure will work or will have negative consequences.
Can any of you please help me?


texts: I want to make an oscillator with 160 MHz

texts:
I want this for my project. So I have decided to make a basic Wien bridge oscillator.

$$f = \frac{1}{2\pi R C}$$

So if I choose a capacitor of 0.1 nano farads and a resistor of 10 ohms, I should get around 160 MHz.
Will I get the 160 MHz, I heard that a wine bridge cancels out higher frequencies.


texts: Microcontroller Constant Power Output - Is this Okay?

texts:
I have found one circuit on this site and I want to use it for my project.

My project is power controlled heater coil. I use low resistance coils in range of 0.6Ω - 2Ω so they must be precisely controlled. How I want to achieve this?

I will use Arduino and first of all I will measure current Voltage on the battery (V BAT).
Desired power will be set in the Arduino code. For example 30W.
Now, If I want 30W power output with 4.2V for example I will need about I = 7.14 Amp to flow through heater. This is calculated by Ohm's Law.
Through DAC I will calculate controller output voltage (U REF) with this formula UREF = I * RREF. So it will be 7.14*0.15 = 1.071V.

Is this circuit okay?

EDIT

Power must be strictly controlled. The coil will work only few second 6-8 times per hour, so efficiency is not important.


texts: Altium Nexus: Linking Managed Sheets to PCB Layout Snippets

texts:
Is there anyway to link Managed Sheets to corresponding PCB layout designs in vault?  I know snippets allows for modular layouts and schematics, but according to what I've read in the documentation, this does not persist in vault and there is no clear link between the schematic snippet and corresponding layout snippet.

Ideally, if I place a Managed Sheet in a new design, I also want the option to place a corresponding layout from vault.  It makes sense to me for the managed sheets to have a link to several pcb layout designs as child items in vault.

Do I have the wrong idea here? At the very least, is there a way to have snippets persist in vault?


texts:
Is it possible to "Power On" notebook PC with Arduino (or with USB keyboard) without pressing notebooks power button ?
Notebook PC is Acer 5720Z.


texts: I frequently see it as the balance port connector on Lithium Polymer batteries, where it comes in 3-wire to 7-wire variants.  What is its official designation?


texts: What is this chip in a old wireless window security sensor?

texts: I opened one of the old window security sensor as I'm curious what wireless technology and chipsets were used. Obviously, this is big antenna, so likely 433MHz RF. But I couldn't identify this chip? Any ideas?


texts: In a semiconductor, why is it said that holes also diffuse?

texts:
Let's say we have a p-type and an n-type semiconductor. I understand that the free electrons in the n-type semiconductor move to the p-type, but why is it said that the holes also move to the n-type semiconductor?

I know that it can sometimes be useful to pretend a hole is actually a particle, like an electron, but wouldn't it be easier to say that the free electrons go to the p-type, leaving behind positive ions in the n-type and creating negative ions in the p-type? Or is this explanation incorrect?


texts: I recently got hold of an LED matrix that I would really like to use in a project. The problem I have is that it uses a 2mm (not 2.54mm) pitch pin header connection for which I can find no standard sockets close by. Making a pcb would be the next best option but by the time it gets fabbed and shipped my holidays will be over. Are there any secret tricks around that would allow me to solder this matrix onto veroboard?


texts: Cyclone V external memory group pins DQ/DQS

texts:
I'm trying to understand the functions of external memory pins  in Cyclone V (5csema5af31c6n)
I do understand that colums HMC Pin Assignment for DDR3/DDR2/LPDDR2 shows pin functions for external memory implementation (using hard memory controller). But for what DQS x8 and DQS x 16 colums? Is this some interface? Why some functions are duplicated? Can't understand it even reading Cyclone V handbook (chapter External Memory Interfaces in Cyclone V Devices) and External Memory Interface Handbook.
Pinout file for 5CSEMA5AF31C6N


texts:
Can anyone tell me what the “C.T.” Stands for in the Secondary Volts column (see pic) stands for? When I see that my mind thinks “current transformer” but this is not a current transformer in the sense that I think of them. I know that current gets “transformed” across any transformer but my understanding of a current transformer is on the order of a Window CT used to monitor motor current or line current in substation, etc.

Image from www.alliedelec.com/m/d/08507f560b87dc69b56b0077e6976f5f.pdf.


texts: Calculating magnitude of a transfer function

texts:
Simple question here, How do I rearrange this:

$$T(s) = \frac{1}{(s + 1)(s^2 + s + 1)}$$

to this?

$$\left |T(j\omega)\right |= \frac{1}{\sqrt{1 + \omega^6}}$$

Wolfram does it and says it works when omega is positive but I'm still lost, doing the calculation for squares I get a huge string of exponents of omega such as the denominator after squaring:

$$-\omega^6 + 4j\omega^5 +8\omega^4 -10j\omega^3 -8\omega^2 +4j\omega + 1$$

The denominator first becomes this and I don't like to proceed further because all directions I have followed I've ended up with a large series such as that above.

$$\left|(1+2 j w-2 w^2-j w^3)\right|$$


texts: What are the Pros and Cons Using a Relay to Bypass LAN with Dual Ethernet Ports after POWER LOSS

texts:
EDIT: The Microchip Ethernet controller only supports 10/100 Mbs
I have verified on my bench that two Magjacks with magnetics built in, and hard wired together, works on the bench using just the communication lines as a bypass to simulate a POWER LOSS from a device with dual ports.
Currently I am using only ONE port. But I want to add dual ports and a switch for daisy chaining and connecting the embedded switch in strap mode so won't have to be managed by the MCU, and KISS concept of not having to implement the STP or RSTP spanning tree protocol.
That way if a daisy chain of devices is used on a network, and one device loses power, that the rest of the networked devices down the line will still have communications.
So if using a "mechanical signal relay" with normally closed NC contacts is used, and there is power, the contacts/switches will be open allowing normal communication. When power is lost, the relay defaults back to its default state of Normally closed NC and hard bypassing the communication lines to bypass the device with lost power so communications can still be maintained to the following devices in the daisy chain.
Pin Connections:

Mag 1
Mag 2

TD+
TD+

TD-
TD-

RD+
RD+

RD-
RD-

Using simple jumpers, I hard connected the MagJacks pins together. I plugged an ethernet cable into a basic consumer Netgear 5 port switch on my network. Plugged the other end into one side of the "MagJacks hard wired input", and then plugged another ethernet cable into the other end of the "MagJacks hard wired other input" to my device with embedded TCP/IP Server that uses both TCP/IP and UDP.
Communication to Web server works like a charm with the magjacks hardwired.
I know there will be cable length limits, but I'm no networking engineer.
Does anyone have any input as to any pros and cons on network cable losses etc using the MagJacks with the built-in magnetics? Or should the magnetics be separate from the ports? With board space, the built-in magnetics help. But I'm not sure if I should use a separate RJ45 connector and separate magnetics/transformer with a true hardware bypass.
There will also probably be a limit of devices that can be in the chain also.
Thanks for any pros and cons feedback anything you could think of. The concept works, but again I am no networking IT expert engineer and any feed back on pros and cons any why's would be greatly appreciated.


texts: Audio Jack Sleeve Switch Schematic Connections

texts:
I'm trying to understand the switch mechanism on sleeve of this jack - I can't work out what it is.

Specifically:

3 is sleeve,
4 is sleeve switch

But what is operation?  Is the sleeve switch N/O and connected to sleeve through the jack inserted?

Part is pj-327a5-smt.  https://datasheet.lcsc.com/szlcsc/1903151105_XKB-Enterprise-PJ-327A0-SMT_C381135.pdf


texts:
Studying for the PE exam, everything seems to be a breeze, but I cannot for the life of me read a TC chart.  Specifically, I have a sample problem in a study guide where the measured voltage is 21.57mV with a 20C junction and a Type J thermocouple.

How to solve the problem is straight forward.  I know I have to account for the junction temperature by adding the voltage at 20C to my measured voltage, then looking up the result in the chart.  I however, cannot read a chart.  Just cant do it.  I seem to also have found multiple charts and online calculators that contradict each, so if somebody could please help me work this out it'd be greatly appreciated.

As far as I can tell, my sources of confusion come from these questions:

1) Some charts number from -10 to 0 in columns, others number from 0 to +10 in columns.  These appear the same, but the value that I add to or subtract from is always a mystery.  Specifically because all charts seem to have a far left value and far right value of the same, and for me it would be intuitive if the right value was always +10

2) Related to #1, is there a case to use one or the other above?

3) Is looking up a cold junction offset value in anyway different than looking up a regular value - In my example problem, I went to my chart to find the mV for 20C, should I be looking a different chart for cold junctions?

From my sample problem textbook, they found 20C -> 1.537mV

From an online chart, I also found 20C -> 1.537mV

From another chart online, I found 20C -> 1.019mV

An online calculator I found says 20C -> 1.019mV

Fluke's online calculator agrees 20C -> 1.019mV

The reference book I have available to me was in Fahrenheit, but 68F -> 1.306mV

All of the values seem to differ by 10C (1.019mV vs 1.537mV), except the Fahrenheit value seems to be about halfway, so I'm sure it's no coincidence that the interpretation of the charts are wrong, but the calculators I just punched it in.  Where am I going wrong here?


texts: Amperage measurements using a analog multimeter

texts: I got this $15.00 Multimeter with Amperage measurement. Do I need to put the test probes in series on the circuit? The maximum range on the multimeter is 250mA. The black probe is connected to the 10A Max socket.


texts:
This is my first question in this stack exchange.
I found my old Reliance Netconnect+ modem and decided to open it up. There is a micro chip with the name QUALCOMM MDM6085 on the top left and EAB857.0 E3135108 on the bottom right.
Intrigued by it I googled the part number but I couldn't find it's datasheet exactly. I was redirected to this page but I am not sure what to choose. I am able to find out that it is a kind of memory here. So, I kindly request to shine some light here and possibly help me to find out more info.
I am currently pursuing my Bachelors degree in Electronics. Hope somebody will explain it in a simple way.
Thank you


texts: How are Sensors Interpreted by the Microcontroller?

texts:
I've always wondered this, how exactly are sensors interpreted by/for the microcontroller?
Like lets use an example of a Heat Sensor...how exactly is something like say.....an Arduino interpreting the data? I mean using a LM35 Precision Centigrade Temperature Sensor which is pretty common but small at the same time.


texts: Writing on one flash memory location could affect whole memory page

texts:
I am working on designing energy meter using PIC18F46K80. When the power goes off the meter store data on the flash memory (credit and so). Meter power supply stores enough energy to supply the microcontroller for 2 seconds to ensure the writing will be correct.

The writing it self is incremental in memory. I mean I write only on empty memory location (0xFFFF). when the reserved memory is full (I reached the last location). I erase all memory pages and start writing from the first location.

My problem is: when I attached a debugging tool that supply the microcontroller 5v directly I don't have any energy store. when this debugging tool is removed while a writing event is occurring, I find that all memory page is erased to 0xFFFF.
I knew that writing in an empty flash memory is only by resetting the bits (0) in memory locations according to the data ( if I understand this in the right way). And when we need to rewrite in the same memory location we need to erase the whole page and rewrite again.

The question is how could writing in one empty memory location in the flash memory erase the whole page?

Note:
I knew it is not a good practice to write such data in flash memory. It is better to use the EEPROM. However, currently I am stick with this design I can't modify to use internal or external EEPROM. Another thing which I will post in other question is the security of storing the credit and private key in external EEPROM.


texts: Any benefits from implementing CSA versus just using multiplication symbol when synthesizing?

texts: I am synthesizing some multiplication units in Verilog and I was wondering if you generally get better results in terms of area/power savings if you implement your own CSA using Booth Encoding when multplying or if you just use the * symbol and let the synthesis tool take care of the problem for you?


texts: Does a specific laser module have a specific amount of power needed?

texts: Does a certain kind of laser module need amount of power, or can I just take the module from different laser and solder it onto a new driver? I want a key chain size laser with interchangeable threaded pattern heads, but I can't find one. The keychain laser only uses 1 aa battery, but the one with threaded interchangeable pattern heads uses 2. So can I just solder the interchangeable module onto the keychain driver?


texts: Powering up analog part of the video card

texts:
I am designing the video card for the device mainly powered by the +5 V of the ATX power supply. The digital part of the video card is also powered by the +5 V supply, as well as analog part. Analog part consists of several opamps, comparator, and some decision making logic (frequency selection PIC, LM1881).

My experience that 5 V power rail may be relatively contaminated to cause problems with the image, and I want to minimize these issues at the design stage. I have previously asked a number of related questions, and this one is about general architecture of powering the analog part.

What are the options for powering the analog part of the video card, and what are pros and cons?

Here are my thoughts so far:

Use regular +5 V power coming through the edge connector of the video card, and filter it using capacitors and ferrite bead. These +5 V may come long way to the card with a number of consumers on it, thus must be relatively noisy. Filtering may help a little, but LC filtering had failed the simulation;
Use other, more cleaner source of power. As an example +12 V, which is not that used in the system. And now another dilemma, how to step down from 12V to 5V:

Use simple LDO. Current is expected to be within 500 mA (maximum, to be safe, nominal must be 250 mA), and it seems to be a killer for the LDO device (3.5 W will require heat sink);
Use cascaded LDO, 12->9 then 9->5. This way there will be two devices dissipating the heat, approximately 2W each. I was told/read that such architecture may cause instability and noise if designed improperly (what is proper design here?);
Use cascaded DC-DC (12->6) and precision LDO (6->5). In this architecture device will have additional noise from the DC-DC converter, and I am not sure if it is better than just using +5 V from the system.

Use separate 5 V powering cord from the power suppy. ATX PSU is having a number of wires to power devices within the chassis, and I theoretically can make additional power connector for the analog part so that PSU would feed the circuits directly. There're clearly some kind of such architectures exist, e.g. modern high-performance GPU cards, but I do not know how they are designed. And I have two issues with this:

video processor and some circuits are not intended for that separate analog and digital power, thus I am not sure what will happen in case analog part of the circuit will accidentally be left without power connection - and if device may be damaged by the resulting currents;
by connecting another PSU wire I will create huge ground loop. I am not able to separate analog and digital grounds in the video processor by its design, thus it will be the same ground wire coming through edge connector and additional power connector.

Any suggestions basing on your knowledge and experience? Any success or failure stories to keep in mind for the decision?


texts: LTSpice Third Part MOSFET Model Won't Work

texts:
I am attempting to incorporate this mosfet model into ltspice:
Part Page
Model

However nothing I do seems to work. I've placed the library both next to the main .asc, and in the ltspice /lib/sub directory. I have not done the main import as I should be able to just include this library somehow and use the default general nmos symbol with it.

No matter what I do I get the same error:

m1: Can't find definition of model "psmn2r0_30pl"

with the model name PSMN2R0_30PL entered into the Value field of the NMOS symbol.

I've tried following this: http://www.linear.com/solutions/5360
and got the following error using:

.lib PSMN2R0_30PL.lib

Error on line 30 : .model m1:mint nmos(vto=2.02612295371271 kp=9.2938e+02 nfs=230000000000 eta=0  level=3 l=1e-4 w=1e-4 gamma=0 phi=0.6 lambda=0 is=1e-24  js=0 pb=0.8 pbsw=0.8 cj=0 cjsw=0 cgso=0 cgdo=0 cgbo=0  tox=1e-07 xj=0 ucrit=1e4 diomod=1 vfb=0 leta=0 weta=0  u0=600 temp=0 vdd=0 xpart=0 vmax=100)
    * Unrecognized parameter "lambda" -- ignored
    * Unrecognized parameter "pbsw" -- ignored
    * Unrecognized parameter "ucrit" -- ignored
    * Unrecognized parameter "diomod" -- ignored
    * Unrecognized parameter "vfb" -- ignored
    * Unrecognized parameter "leta" -- ignored
    * Unrecognized parameter "weta" -- ignored
    * Unrecognized parameter "temp" -- ignored
    * Unrecognized parameter "vdd" -- ignored
    * Unrecognized parameter "xpart" -- ignored
Direct Newton iteration failed to find .op point.  (Use ".option noopiter" to skip.)

I'm somewhat clueless as to what's going wrong here. Does anyone know how I can properly import this without having to import and redo the whole symbol?

Thanks!


texts:
Why is the 5A at the 10 000V winding is directed upwards? Is that because of Lenz's law?

Edit:
Given a 50kVA power transformer that has a voltage rating of 10000/200 V, I know that the high voltage winding is 5A and of the low is 250A. From that how do I know to place the both currents 250A, 5A into the node?


texts: Why would a BLDC motor be "noisy" in reverse

texts:
I have a BLDC motor on a controller I built running in both forwards and reverse.

However the reverse direction is substantially noisier than the other and the motor vibrates more almost as if the commutation sequence were wrong.

I am using the same sequence for iterating through the 6 commutation states in either direction based on the hall status.

For going forwards I take the position from the hall sensors and map that to N "state" in my list of 6 states, I then set the motors to N+1 state.

For going backwards I do the same but use the N-2 state. (modulo 6)

I am working on the assumption that N+1 is magnetic field in advance of the poles by of 60-120 degrees, N is 0-60 degrees, N-1 is -60 to 0 degrees and N-2 is -120 to -60 degrees - this seems to hold true experimentally using the N and N-1 states, the move, but slowly and jerkily.

I'm using a very low duty cycle PWM (10%) at the moment with a 32V power source (the motor is rated for 48V - this motor specifically https://en.nanotec.com/products/2873-db59c048035-a/)

Why would it consistently behave fine in one direction, but not the other?

Thanks


texts: Running different voltage motors from one battery

texts:
I would like to run a 12v motor and a 24v motor both from a 24v battery, through an Arduino. Is it possible to use a regulator for just the 12v motor to stop it being damaged, but still get the full 24v to the 24v motor?

Also, could the Arduino be powered from the same battery, I believe it operates at 5v, or does it need its own power supply?


texts: Can I charge multiple identical devices in parallel from on transformer

texts:
I have four identical devices (HDD enclosures), each requiring 12V, 2000mA. Each of them came with their own power supply/DC transformer, but they are fat and chunky, and if possible I'd like to recover some sockets space on my multi-socket adaptor.

I had though to take one of the power supply unit, and simply splice on the end of the other three units on to the output wire, forming a 4 piece y-cable of sorts.

This answer to another similar question seems to indicate so, but will the transformer be able to supply enough current to the enclosures in parallel?


texts: How do I use Lithium Polymer batteries in a very high draw system without tripping the overload protection?

texts:
UPDATE:

Firstly, let me say thank you for all the responses. I appreciate it.

Further to my last, I today tried a little experiment - I ran my 3Ah 12v lithium polymer battery to a heating element through a variable voltage tester I made (basically a potentiometer with a voltage gauge attached). I also connected my multimeter to measure the amperage.

I found if I kept the voltage to around 5v, this kept the power consumption to about 2.8A and the element worked, although it didn't get very hot.

If I went to 6v, the power went to 3A and the battery overload protection kicked in.

Tomorrow I'm going to try using a regulator to output 5v and see if I can make it work that way. If it does, then in theory I could attach any battery to the system (over 3Ah) and not have to worry about the overload protection.

Thank you all again for the help - I'm certainly heading in the right direction.

ORIGINAL POST

First off, let me start by saying my speciality was automotive engineering and as such I am a hopeless duffer when it comes to the magical dancing pixies of electricity, so go easy on me.

Since I retired, I've been building all kinds of weird stuff in my workshop in the garden, one of which is smoke generators; specifically small ones, from a few inches on a side down to my smallest which is less than an inch square.

I've built loads of the things for various projects and it's all been fine. I power them from sealed 12v 1.2Ah lead acid batteries, the kind you get for alarm systems, and they work great, to a point. The trouble is, I want to improve the electrical side more. I'd like to use 12v Lithium batteries, add timers, Arduino controls and so forth, but the problem is whenever I try to do this, the inbuilt overload protection in the battery kicks in and shuts it all down.

I think I know why this is happening - the heating element in the smoke generator is basically shorting out the battery - I'm using resistance to turn the electrical pixies into heat (the element wire comes from a hair dryer), so what I need is a way to limit the current going into the generator (I think).

Now, as I mentioned, I'm useless with this kind of stuff. I can build basic circuits, solder and such but other than that I'm at a bit of a loss. I put a multimeter on it and it looks like it's drawing about 6v and 10A, which is kicking the snot out of it as it's a 1.2Ah battery, so I'd also like to do this to help save the battery as they have a very short lifespan because I'm abusing the heck out of them. I can use higher capacity batteries, but they're obviously bigger and heavier which kind of defeats the object of making tiny smoke generators.

Basically, I want to limit the output from the battery to avoid tripping the overload protection on the electronics. I tried using a 10ohm 10w resistor to limit the draw, which works on the multimeter (output is 11v 1.1A) but the resistor soaks up all the power so the element doesn't heat up.

Any assistance would be greatly appreciated.

For info, I've added a link to a short video showing one of the smoke systems in operation to give an idea of what I'm rambling on about.

https://www.youtube.com/watch?v=kOHjtKtAjMY


texts: I drew my pcb in eagle with polygons' isolation is set to 0(default) but I need to change it to 0.35mm. I have lots of polygons, doing it manually is too hard. Is there a way to change all polygon's isolation?


texts:
I'm trying to find an IC implementing 2-1 multiplexers, but I could only seem to find chips like this: SN54LVC157A - Quadruple 2-line to 1-line data selectors/multiplexers.

Where there are 2 groups of multiple inputs and 1 of these groups is selected for the output (essentially a bunch of 2-1 muxes with shared select inputs). Instead, I want 2-1 muxes where there are separate select inputs. Anyone know of such a chip? Or is there a reason why these are not readily available?

Basically, we need to implement some combinational logic on a breadboard for a lab, and we found we could do it with significantly less gates if we use muxes.


texts:
USB specifies 4 pins:

1.   VBUS   +5V
2.   D-     Data-
3.   D+     Data+
4.   GND    Ground

Why is this not 3?  Could the Data and Power not share a common ground?  Am I correct in understanding that D- is the ground for D+?


texts:
The context is that I want to build a tunnel laser effect, that modulates the angle of the cone according to a sine wave. The purpose being, to create a cool Borg weapon effect for a Star Trek Borg cube model.

Constraints are size (8 inch cube) and cost (just a model, so not looking for a lot).

The tunnel laser seems easy, angled mirror on a motor deflecting the laser. The trouble is in modulating the angle. One method I've thought of is to modulate the motor speed, to increase/decrease the centrifugal force, which will push the mirror into a more flat shape (with some sort of spring tension resisting it) as it increases.

My question is generally what's the easiest way of modulating a voltage/motor according to a sine wave?

I have thought of maybe getting a Raspberry Pi with controller board for this, but I don't know much about the available controllers.

I wonder if perhaps there exists some sort of X-Y controller motor package for manually setting the laser direction at high speed? Which is what I believe the high end laser effects use.


texts:
I have written a simple Python program which runs on a RPi to make an LED blink. For that I connected my RPi using GPIO 23 with the anode of the LED, and before going back to ground, I added a resistor with 220 ohm. So far, this works.

Now I would like to make two LEDs blink, so I just thought to add a second LED and put them in series. Unfortunately, exactly nothing happened. So I have a number of questions:

Why does nothing happen? Are the 3.3 volts of the RPi too little for two LEDs and a 220 ohm resistor?
Is it even correct to put the LEDs one after the other, or would I need to put them in parallel?
How do I calculate the correct resistor, if I don't know the data of the LEDs? What would happen if I simply remove the resistor? Would I risk damaging the RPi?


texts: What's the function of ground wire anyway?

texts: I thought Ground wire in house electrical systems was used in order to discharge electrical currents to the earth. However, I've seen people saying ground wire would drive electric current to fuses, when there was a short circuit, in order to avoid damaging people, or the system. Can someone help me understanding this?


texts: Reading high voltage output NPN proximity sensor with Ardunio YUN

texts:
I have a NPN proximity sensor with rating voltage 6-36 VDC.
(https://www.amazon.co.uk/gp/product/B07SD9VYDH/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1)

To power it up, I use a 24 VDC power supply and buck converter to step down the voltage to 9 VDC.

When the sensor is idle, the reading voltage shown by a multi-meter is the voltage supplied by power supply (9 VDC).

The problem is input PIN Arduino operates at 5 VDC. So I need to check whether this sensor works with pull-up resistor before connecting it to the Arduino.

Below is the wiring that I made

following the schematic from here  Theortically speaking the measurement of output voltage should be equal to pull-up voltage which is 5 VDC from Arduino. However, the measurement that I got was 7.5 VDC.

Can anyone tell me what's wrong with the wiring? or with the schematic?

Many thanks


texts: Why do the capacitors inside the inverter heat up?

texts:
I'm having a problem with the inverters of textile machinery. The machine I work with is the Rieter brand Ring machine and the main inverter, the part is defined as 75 kw U1. 12 units 2200 uf 400 volt capacitor inside the inverter and sometimes  capacitors from the condenser block often overheat and then break.  When I replace the deteriorating capacitor, the fault usually goes away. There are 20 textile machine so each month an inverter is breaks. But I can't figure out what caused the heatimg. The inverter has fluid circulation and fan system inside and operates.

What is the function of 12 pieces 2200 uf 400 volt capacitors in the inverter, and do you have any idea why the capacitors are heating up?


texts: Weird output voltage on op amp triangle wave generator


texts: Strange electrical noise from stepper motor

texts:
It's my first project using arduino. Simply trying to rotate three identical stepper motors, using three 293d h-bridges.

Although it does work properly (meaning the motors do rotate as they should), after the second or third rotation, they start to make a whirring electrical noise -when not moving.

I have attached a schematic of my circuit. The power supply is 5v dc 16A (old computer psu).

You can see exactly what I am experiencing on this video I made (try to listen in closely).

Video with noise.

Update: I checked by touching the h-bridges at the same time the noise starts, and I can feel them getting really hot.


texts:
I have to sample an external clock with a faster FPGA internal clock. The main issue here is that I initially thought it could be easily done with something like:

always @(fast_clk)                  // fast_clk is the internal clock
    slow_clk_dl <= slow_clk         //slow_clk is the external clock

But it appears it can't. The reason for this is that after simulating such a signal, I realized that since the two clocks are not synchronized, the sampled output had its duty cycle changed.
What does it mean to sample a clock with another clock? I would appreciate it if you could provide a sample code snippet to explain. Thank you.


texts: How can I make a plated-through hole in Eagle?

texts:
I have mounting holes (0.125 in) at the corner of my PCB project in Eagle, made with the standard "hole" tool. However these are not electrically connected to anything.

There doesn't appear to be a way to make these plated through by specifying a net (unlike a via).

If I want my mounting holes to be connected to the ground plane, do I have to just make an oversize via? Is there some other way?


texts: MPLAB X XC8 error expression is not assignable and invalid digit 'F' in octal constant

texts:
I am programming a PIC16F887 with MPLAB X,
the compiler is XC8 v2.10 and the hardware tool is PICkit3.

When compiling the program I get these errors in the following constants of the program.

control.c: 125: 12: error: expression is not assignable
ADON_bit = 1;

control.c: 126: 3: error: invalid digit 'F' in octal constant
C1IE_bit = 1; // enable analog coparator interrupt

control.c: 126: 12: error: expression is not assignable
C1IE_bit = 1; // enable analog coparator interrupt

control.c: 130: 5: error: invalid digit 'F' in octal constant
GO_DONE_bit = 1; // start analog-to-digital conversion

control.c: 130: 17: error: expression is not assignable
GO_DONE_bit = 1; // start analog-to-digital conversion

My program code is as follows:

#define PWM_MIN_DUTY 80
#define PWM_START_DUTY 200

#include <xc.h>
#include <pic16f887.h>
#include "config.h"

void AH_BL();
void AH_CL();
void BH_CL();
void BH_AL();
void CH_AL();
void CH_BL();
void bldc_move();

unsigned int bldc_step = 0;
unsigned int motor_speed, i, j;

void Interrupt()
{
  int j;
  for(j = 0; j < 9; j++)
  {
    if(bldc_step & 1)
    {
      if(!C1OUT_bit)
      {
         j -= 1;
      }
    }
    else
    {
      if(C1OUT_bit)
      {
         j -= 1;
      }
    }
 }
 bldc_move();
 C1ON_bit = 1;      // clear the mismatch condition
 C1IF_bit = 0;      // Clear comparator 1 interrupt flag bit
}

void bldc_move()
{
   switch(bldc_step)
   {
     case 0:
     AH_BL();
     CM1CON0 = 0xA2;
     break;
     case 1:
     AH_CL();
     CM1CON0 = 0xA1;
     break;
     case 2:
     BH_CL();
     CM1CON0 = 0xA0;
     break;
     case 3:
     BH_AL();
     CM1CON0 = 0xA2;
     break;
     case 4:
     CH_AL();
     CM1CON0 = 0xA1;
     break;
     case 5:
     CH_BL();
     CM1CON0 = 0xA0;
     break;
   }
   bldc_step++;
   if(bldc_step >= 6)
     bldc_step = 0;
  }

  void set_pwm_duty(unsigned int pwm_duty)
  {
    CCP1CON = ((pwm_duty << 4) & 0x30) | 0x0C;
    CCPR1L  = pwm_duty >> 2;
  }

  void main()
  {
    ANSEL = 0x10;
    PORTD = 0;
    TRISD = 0;
    ADCON0 = 0xD0;
    ADFM_bit = 0;

    INTCON = 0xC0;
    C1IF_bit = 0;

    CCP1CON = 0x0C;
    CCPR1L  = 0;
    TMR2IF_bit = 0;
    T2CON = 0x04;
    PR2 = 0xFF;

    set_pwm_duty(PWM_START_DUTY);
    i = 5000;
    while(i > 100)
    {
      j = i;
      while(j--);
      bldc_move();
      i = i - 50;
    }

    ADON_bit = 1;
    C1IE_bit = 1;

    while(1)
    {
      GO_DONE_bit = 1;
      __delay_ms(50);

      motor_speed = (ADRESH << 2) | (ADRESL >> 6);

      if(motor_speed < PWM_MIN_DUTY)
         motor_speed = PWM_MIN_DUTY;
      set_pwm_duty(motor_speed);
    }
  }

  void AH_BL()
  {
    CCP1CON = 0;
    PORTD   = 0x08;
    PSTRCON = 0x08;
    CCP1CON = 0x0C;
  }

  void AH_CL()
  {
    PORTD = 0x04;
  }

  void BH_CL()
  {
    CCP1CON = 0;
    PORTD   = 0x04;
    PSTRCON = 0x04;
    CCP1CON = 0x0C;
  }

  void BH_AL()
  {
    PORTD = 0x10;
  }

  void CH_AL()
  {
     CCP1CON = 0;
     PORTD   = 0x10;
     PSTRCON = 0x02;
     CCP1CON = 0x0C;
  }

  void CH_BL()
  {
    PORTD = 0x08;
  }


texts: What kind of MOSFET to use with this battery protection IC

texts:
I'm working on this hobby project and I am trying to create a PCB for it.
I want to power the project with 2 18650 batteries. Because the product needs to be used by other people as well, I would like to build in some protections. One of them is over-voltage, under-voltage, reversed polarity, and short circuit. Herefore I found a protection ic.
The rest of the PCB consists of an ESP32, WS2812 LEDS x 24, ICM-20948. The total current that can be drawn would be around 2.5 Amps or max 3 Amps.
For the protection IC, as seen in the datasheet, there need to be 2 MOSFET's. I have tried to search on the internet on how to choose which MOSFET is suitable for the protection IC and application. But I just can't figure out what is good or not. So now I have tried this with the following products.
Protection IC - R5460N208AA-TR-FE:
Datasheet
Product page
N-Channel MOSFET - CSD17484F4:
Datasheet
Product page
Battery Protection circuit

Battery Holder

My choice of the current MOSFET's is based on this information:
How to Select a MOSFET – Battery Protection
The current design is also based on the typical design of the battery protection IC.
I'm not an expert on creating PCB's so there will be stuff that isn't correct if so I would like to know as well and if you have some tips or good instruction videos or posts I'm always in for that.
So now I have 2 questions.
1 - Did I choose the correct MOSFET's?
2 - Am I doing any good on the design?
For the full schematic look on my GitHub repository -> Taekwondo - PCB


texts:
I want to make a VU Meter and in order to do this I need an audio input for the VU Meter but also I want to be able to listen to the music on my PC of course. I wanted to know if I can use one of those cheap 3.5mm splitters (attached image) and get no quality loss (for the VU Meter is not mandatory but for the speakers is necessary), or how can I achieve this task.

At first I tried using 2 outputs of my motherboard audio card but I configured to use one of them as lateral speakers (for the VUM. signal) and the main as frontal speakers but Windows doesn't reproduce the audio in both just in one, so I need another alternative.


texts: Two 12v 1A DC power sources using a 1 gang switch?

texts: I'm wondering if it is possible to connect two 12v 1A DC power sources to a single switch? And if so, how would such a schematic look like. The two power sources will then power their own things.


texts: Why is voltage drop independent of this 4 Ohm resistor?

texts: I have this resistor which is connected to some battery (not very important). I don't understand why the total voltage is equal to the voltage drop over the 3 \$ \Omega \$  and 2 \$ \Omega \$ resistors. Why is it not dependent on the resistor in the middle with 4 \$ \Omega \$ . I do understand it if the 4 \$ \Omega \$ were substituted with a wire. But how can it be that there is no difference whether it is 4 \$ \Omega \$ or 0 \$ \Omega \$?


texts: DSLR Hotshoe wiring to Arduino revisited - I'm getting false triggering. How can I overcome that?

texts:
I read this post of 7 years ago:DLSR Hotshoe wiring to Arduino
I built the exact circuit described in the answer, shown below, to detect when my canon DLSR hotshoe would send a "trigger" order to the flash. This trigger signal could then be dealt with by an Arduino.

This is the hotshoe of the Canon camera below:

My Arduino detects when I fire the flash (pull trigger to GND,) but the weird thing is that it also detects when I half-press the shooting button, and sometimes keeps detecting if I keep the button half pressed for some time.
When I do shoot it always detects normally, so it works, but something is false triggering when I half press the button - and it's random.
If the camera is on and I don't press the shooting button, it works normally as it should, never detects any false "triggering".
What could I do to fix it? Is the Canon hotshoe trigger different from others?


texts: A NOT gate with gradual changes between state

texts:
I have a simple NOT gate circuit with the following arrangement.

LED D1 will light up by default. If I push SW1, the transistor Q1 will activates and D1 will be turned off. This NOT behaviour works just fine.

The problem is, I want D1 to turn off gradually (the gradation has to be noticeable by humans, so 1 or 2 seconds would probably enough). I put the capacitor C1 for that very reason. I thought by having C1 in that position, the activation of Q1 could be made gradual, because initially currents would be consumed by C1's charging.

It doesn't work. D1 still have an abrupt change of state from ON to OFF. I wonder if I did something wrong with the circuit design?


texts: Generating C code from a Matlab-Simulink: errors encountered during linking

texts:
I generated C code from a Matlab-Simulink model (In Matlab help is "Parametric Audio Equalizer"

-> "Task 6 - Integrate Device Drivers" -> "Configuration C") with a "Target Preferences" module

for a "OMAP_L138/C6748 EVM" Board with a "OMAP138" Processor.

With the Incremental Build option (Simulink), the Code Composer Studio project is generated,

compilated, but when is linking I get this error in Simulink and CCS:

SIMULINK:

The call to idelink_ert_make_rtw_hook, during the exit hook generated the following error:
Error while building the project.
The build process will terminate as a result.

CCS:

[Linking...] "C:\CCStudio_v3.3\C6000\cgtools\bin\cl6x" -@"CustomMW.lkf"
<Linking>

undefined           first referenced
 symbol                 in file
---------           ----------------

_PMI_getModuleState  C:/CCStudio_v3.3/bios_5_33_06/packages/ti/bios/lib/bios6748.a674<pwrm_set674.o674>

_PMI_setModuleState C:/CCStudio_v3.3/bios_5_33_06/packages/ti/bios/lib/bios6748.a674<pwrm_set674.o674>

__PWRM_CAPSMASK C:/CCStudio_v3.3/bios_5_33_06/packages/ti/bios/lib/bios6748.a674<pwrm_set674.o674>

error: unresolved symbols remain
error: errors encountered during linking; "audioworkflow_devdrivers.out" not built

Compilation failure

Build Complete,
1 Errors, 0 Warnings, 0 Remarks.

Thanks


texts: Connect an I2C camera to computer via USB as a webcam

texts:
I took out of an old security camera its circuitry and I am trying to figure out a way to connect it via USB to my computer and use it as a standard webcam. Is it possible? Here are the front and the back of the camera circuit. There are the 12V, GND and Video pins. But also there are the 3.3v, SDA, SCL and GND pins which are unused. Maybe those pins can be used to extract image data from the CMOS, but I'm not entirely sure about that. But maybe, is it possible to just take the analog VIDEO pin and convert it to digital data and use the stream as a webcam? Thanks.

Front

Back


texts:
I tried to simulate a circuit with mosfets in LTspice, but it's still hard to understand how they work

What I observed:

For N-channel MOSFETs (as in the picture above)

a) Current flow through N-channel MOSFET transistor

Does not depend on V1's voltage
Depends on V2's voltage
Does not depend on the current charging the gate (from V2)

b) Voltage across R3 is never higher than V2 - V1 (even if R3 resistance goes to infinity) and it doesn't depend on the V1's voltage.

c) The current charging the gate is extremely low (about 0.0002fA).

For P-channel MOSFETs

a) Current flow through P-channel MOSFET transistor

Does not depend on V2's voltage
Depends on V1's voltage
Does not depend on the current charging the gate (from V2)

b) Voltage across R3 is almost equal with V1's voltage

c) The current charging the gate is extremely low and it's not constant.

Please tell me if I said something wrong.

EDIT:
The only thing I don't understand is, considering the schematic in the picture above, why does the voltage across R3 can not be grater than 8V, no matter how big R3 resistance is? I expected it to be 9V with a big resistance.

Thank you for your answers!


texts: My question is, how can I calculate the input impedance of this circuit? I want to find the expression, that describes the input impedance.


texts: How did an LED go from being a point source of light to an extended source?

texts:
A night light with an LED under a dome screen projected a sharp image initially, but a blurry image after the first night. The screen appeared to be undamaged, this led me to believe that the LED started out as a point source and after some time (more than 2 minutes, but less than 12 hours) the light-emitting area spread out. I'm curious what the physical process behind this phenomenon is.

The LED looks to be ~1mm square, the whole area seems to light up. I don't have one that is still a point source – we ordered a few more as cheap gifts, but the others all arrived blurry out of the box.

From my rudimentary knowledge of diodes, I imagine the entire junction should either be allowing current to pass, or none of it. If an imperfection creates a zone that becomes conductive first, the current should spread over the whole junction quickly... should it? Or if part of the junction starts out as more conductive, there would be a huge change in brightness as LEDs "break in" from equalizing... wouldn't there?

Is there some alternative explanation that I didn't think of?


texts: Is a ground plane meaningful even where the signal return path is not through ground?

texts:
I'm designing a two layer PCB for a keyboard where most of the board space is taken up by the key switches and backlight LEDs. The switches have a traditional switch matrix configuration with diodes and the LEDs are charlieplexed. Thus, none of the current for the switches and LEDs will actually return through ground.

Of course, there is also an ARM MCU with a crystal oscillator, I2C between the MCU and the LED matrix chip. The ARM MCU will be placed wherever it will fit since the board is jam packed with switches and LEDs and this means I will have to run USB traces from that part of the board to the rear where the connector will be.

My initial idea would be to have as many signal traces as possible on the top and a ground fill/plane on the bottom. I would then only take short jumps to the bottom layer where needed in order to keep the ground plane as contiguous as possible. However, since this is a switch and LED matrix, traces crossing each other is inherent to the design. If I could use both layers for the matrix, that would greatly reduce the number of vias needed and simplify routing.

So the question is, is there any downside to limiting the ground plane only to the area around the MCU and LED matrix controller chip? As I said above, none of the return paths for the matrix goes through ground. What would be purpose of ground be in the matrix part?

Also, since USB has to be routed from the MCU to the rear, should I just put a wide "ground strip" under the USB lines? How wide would that be?

Of course... I could also got to a 4 layer board and all of this would be solved but that sounds excessive for a simple keyboard.


texts:
We have a small PCB that has been manufactured and assembled several thousand times. However, the last lot showed inconsistencies with the solder mask:

It looks like the solder mask is very thin, almost exposing the copper. The expected color would be what you see next to the SOT23 pads.

We contacted the PCB manufacturer about this, who claims that it is most likely an issue from too high soldering temperature or too long solder duration.

So we contacted the assembly company, but they say that the soldering process did not change from the previous runs and it must be a problem with the PCB manufacturing process.

Did anyone experience this kind of issue and what is the likeliest cause?
How critical is this? I can't quantify if I am looking at slightly less solder mask or nearly no solder mask at all.


texts: low voltage battery disconnect from regulator

texts:
I am regulating a lithium ion battery to 3.3V and I want the regulator output to shut off when the regulator can no longer supply 3.3V. I am having trouble finding an IC that would do this, and this charger with a low battery disconnect is all I could find: http://cds.linear.com/docs/en/datasheet/4071fc.pdf

It says there is low battery disconnect from VCC at 3.2V.
It says under "Applications" that it is for energy harvesting, so I don't understand if it's really suitable for what I want to do. I need a charger in my circuit too, so that would be useful. I want to make sure I'm looking at this correctly...is there a better way to do this?


texts: How to measure high current (20A DC) using arduino

texts:
I would like to be able to measure the power of a load connected to a 12V battery - this load takes around 20A and I would like to be able to store this using an arduino.

My first attempt was using a shunt resistor to calculate the series current then multiply this by the voltage recorded across the terminals of the battery using a voltage divider - but the issue was that the ADC couldn't pick up the small voltage of the shunt (14mV) and I'm wondering whether i should use an op-amp to amplify the voltage or to take a whole different approach, because I would like a voltage resolution of 0.1mV.

I've been looking into using an INA219, but i'm unsure if it's capable of this resolution or able to measure the voltage considering the high current.

Thanks