texts:
I've purchased a small WS2811 5050 RGB LED strip. I want to light them up without any controller currently. But I'm struggling to do that.

The strip I'm using:

http://www.ebay.co.uk/itm/201709948864?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I've got a 12V Switching Mode Power Supply (L06BR) connected to both positive, and ground of the strip (both sides). And I get nothing?

Not sure what I'm doing wrong here, do I need a controller to simply power it up? Maybe the Amps are too low? Running off 1.7A - but I gathered I don't really need that many amps to power a 48 LED strip.

I would like to eventually hook this up to my Arduino and get some colour changing on the go! :)

Thanks.


texts: How could the Gate-Source potential difference be neglected?

texts:
I’ve been reading the book

  Electronic Principles by Malvino

In the Voltage-Divider bias section of JFET, if gate current is negligible then how did Gate Voltage attain a negative value, given Vdd is a positive value.

And also, to calculate drain current Gate-Source potential difference was neglected compared to Gate voltage.

How were the above conclusions drawn?


texts: Deliver a 40kHz & >40V cosine wave to a transducer for communication

texts:
I'm trying to do on/off keying (OOK) to transmit messages with ultrasound.
This is the transducer.
This is the schematic of the signal generator and amplifier:

It seems that the class A amplifier doesn't work.

Have I made an error with the operating point?
Should I instead use opamps?

If you know how to fix this approach or if you have any better ideas please let me know.


texts: Is the bulk output deliberately used in DRAM cells?

texts:
Regarding the structure of a DRAM cell with a MOSFET and a capacity, why does activating the word-line make the transistor connect through?

As I learnt, the MOSFET becomes conducting if UGS >> Uthreshold. I could only imagine the capacity being the source, but in this case and if the DRAM cell has been charged before, the MOSFET would never become conducting (in the near future before 'natural' discharging).

I also read on the German Wikipedia* that it is actually the voltage across Gate and Bulk UGB which controls the current between Drain and Source. Is this the case for the schematic shown below?
(This is sadly not explicitly pointed out on many Internet sites, therefore my question here.)

Image licensed under CC-BY-SA 3.0 by JürgenZ. from Wikipedia: https://en.wikipedia.org/wiki/Dynamic_random-access_memory#/media/File:DRAM_cell_field_(details).png

*) Feldeffekttransistor#Isolierschichtfeldeffekttransistor, second paragraph


texts: In this diagram of JFET transistor the depletion region is narrower at one end and wider at other end. Why is that so? Is it due to the voltages applied at gate and drain?


texts: N Connector - Best mount for PCB and how?

texts:
Up until today i've ezperimented with antennas by basically taping the coax endpoint to my breadboards and it's been working "so so" and I'm looking for a PCB connector for my N Connector cable.

Any ideas what to get and how you connect those? Anything special to consider?

(source)


texts: In this link is a description of the Altera DE1-SoC kit, and the bottom of the page shows the diagram of the SoC-FPGA chip. It shows some peripherals are connected to the FPGA and other are connected to the HPS. The question is, Does that implies that peripherals  connected to the HPS I can't use them with the FPGA and vice versa ?


texts: Confusion about cutoff mode of NPN transistor

texts:
In the diagram below the npn transistor is in the cutoff region. The book says that both EB and CB junction are reverse biased. My question is about:

A) the EB junction. How is it reverse biased? Isn't it zero biased since both base and emitter are grounded?

B) also the book says that in cutoff region entire Vcc will be available at output. But what about the voltage drop at resistor connected to collector? Isn't output voltage supposed to be less than Vcc even in cutoff region?


texts: Calculating the peak output voltage from RMS power of an audio amplifier

texts:
I want to calculate the peak voltage output of an audio amplifier when driving at its maximum rated power, a loudspeaker.

For example, an amplifier rated at 50 W RMS into 8 Ω, driving an 8 Ω loudspeaker.

This wikipedia article tries to explain what RMS power actually means, but it's not clear. And I'm wondering if it's actually wrong where it says:

  [RMS Power] is proportional to the RMS voltage

This seems wrong, since I know that the equation for power/voltage/resistance is:

$$ P = \frac{V^2}{R} $$

So assuming that the amplifier does not distort, does not exceed 50 W RMS and so on, what is the peak AC voltage it would output?


texts:
I am trying to decide location of AC coupling capacitors between FPGA and PHY SGMII interface and datasheets of neither part has any useful information.
I've read some notes, like this one from Dr. Howard Johnson and posts here on StackExchange where people providing pros of placing AC coupling caps near a transmitter.
However I've also seen many other app notes such as this one from TI, SCAA059C that have AC coupling caps located near a receiver but not providing any reason for it. Electrically is there any benefit or reason to place AC coupling caps near a receiver?
Also, I've seen some designs where caps are placed like below. If caps on transmitter side (or receiver side) is better , why would one design like below? Could there be any practical reason why below locations might provide more benefits?
.


texts: Circuit analysis of series diode clipper circuit

texts:
simulate this circuit – Schematic created using CircuitLab
I'm really unsure how to start with this. The instructions said to find Vin such that Vout will be 0.5Vin. The only given is Vd = 0.7 and Rd = 5 ohms. I tried to do a KVL equation but then I don't know what the current is since Vin is not given.
Additional info:
Diode model that is used is the constant voltage drop model with resistance of Rd=5 ohms and forward voltage of 0.7


texts: Reception without interrupt in USART of PIC18

texts:
I would like to know how to receive data without interrupts in the PIC18 controller.
After setting the USART settings and baud rating, what things must be done so that USART receives properly without use of interrupts?

I'm using it in asynchronous mode. I have tested the transmission process successfully by checking the transmit bit in the USART TXSTAT register.

I have seen using a TRMT bit for tracking status of transmission in the EUSART register. But what can be used for receiving?

I did not see a similar pin in the RXSTAT register for asynchronous mode.


texts:
Implement Z using single 2x4 decoder with 1-enable and active low outputs without logic gate and no complemented literals

Z = A'BC'DE + (D'+B)' + BDE

My attempt at Simplified SOP

Z = A'BC'DE + (D'+B)' + BDE
Z = A'BC'DE + DB' + BDE
Z = BDE(A'C+1) + DB'
Z = BDE + DB'

Answer:

I have the answer but i can't seem to figure out how to use the values to construct the decoder


texts: If I have a circuit which have current consumption 100mA, what is the value of the fuse that I have to select so to open (burn) the fuse in the case of a short circuit? There is a theoretical or practical rule?


texts:
The U1:A(+IP) represents my input (0 to 6V).

I am trying to power a lamp which requires at most 6V@100mA, the input will vary between 0 and 6V but it doesn't provide enough power for the lamp (the input comes from another op-amp used to convert current from 0 to -2mA to a voltage between 0 and 6V).

As wikipedia states, this circuit is a Voltage follower boosted by a transistor :

This particular circuit is very interesting as it provides these curves (for both voltage and current in the lamp) :

However, I am not able to figure out why this works, why is it able to work between 0 a 0.7V, when the transistor shouldn't let anything through ?

Thank you everyone, thanks to you I understand better how this circuit works.


texts: How does a ranged voltage battery charger work?

texts: I'm wondering how a battery charger works that can take different voltages. For example Panasonic EY0L81 with voltage range frlm 10.8 - 28.8v, how does it identify which voltage to charge?. I also have a Bosch AL 1404 7.2 - 14.4v.


texts:
I'm designing a ultra low noise smps and I have some questions about ground/earth chassis. The main goal is very low noise on DC output.

Earth (PE) should be connected to one point (only) to the chassis ground?
AC line usually has two Y capacitors after common mode choke connecting earth. This connection should be at chassis or I should connect to single PE point (as in question 1). What's the best value for those Y caps?
Primary side and secondary side transformer have Y capacitors connected across. Should I keep those if I use earth/chassis (I assume I will keep them in place since I want a short path for noise to return)?
DC side ground. In some designs I see it connects to chassis (that's connected to PE) using capacitors. In other designs I see it connects direct. What's the best way keeping in mind original goal?
DC side. I see that even the + is sometimes connected to chassis ground using capacitor. Should I make two connections to chassis ground on the DC side or should I take both (using wire) to single point connection (where earth connects to chassis)?


texts: ATmega328 external crystal capacitor requirements

texts:
I am reading this guide and it states that, in order to use an external 16 MHz crystal for an ATmega328, I need two 22 pF capacitors.
I found this bundle of two 20 pF capacitors and the crystal (sold specifically for this purpose).

I'm wondering if there's any difference between using the 22 pF and the 20 pF capacitors provided with the bundle.


texts: Why does the cathode heat up more than the anode in an electric arc?

texts: I have recently built a flyback transformer driver with a 555 timer, and have been drawing electric arcs. But I noticed that the cathode electrode(the HV pin on the transformer) heats up a lot more than the anode(the HV cable on top of the transformer). I noticed this because if I use thin cables as electrodes, the cathode starts melting and getting red hot a lot faster than the other electrode. My question is why does this happen. Thanks


texts: DC Step-up Boost Voltage regulator (High Ampere)

texts:
I’m working on a project, where I want to go from 5 Lithium-ion cells in series, to 5 Lithium-ion cells in parallel, for versatility purposes i.e. in time, I want to be able to change the output voltage from 5-60V, hence the step-up voltage regulator approach.
What I want to achieve is:
To connect a 3.7V Lithium-Ion powersource, to a DC motor (from a powertool) rated at 18V.
Later I would like to repeat this for other voltage motors as well.
Is it realistic to build this on a print at the size of circa 10x10x1 cm or 4x4x0.4 inches
For now, I have tried to use an off the shelf Pololu U3V70X Step up voltage regulator with some success. I can get the correct output (18V), however at a very small Amperage, not enough to run the motor.
I have also tried to put 3 regulators in parallel, to get higher Amps with some success, but this is not optimal as the Voltages need to be perfectly adjusted.
I have tried to put 3 regulators in series with individual cells as a source, this is needed as the voltage regulators share a common GND (GNDin = GNDout), with an output of 6V each = 18V.  This works, however, I still find the Amp output to the low side as I would like to reach 20A max discharge, as this is needed when i start this specific motor.
I can se from the answers, that one of the main concerns are the stall currents of 130A.
A few specs for my setup:
Current working setup from the battery manufacturer:
5x LGDBHE21865 2.5Ah in series = 20V (5x4V) * 2.5Ah = 50Wh
Std. discharge 500mA
Maximum discharge 20A
Link to cell specs: https://secondlifestorage.com/showthread.php?tid=1938
Wanted setup:
5x LGDBHE21865 2.5Ah in parallel = 4V * 12.5Ah (5x2.5Ah) = 50Wh
With a step-up boost controller taking 4V->18V with approx. 2.5Ah and stil a max discharge of 20A
Motor specs:
Mabuchi RS-775WC-8514  Vin = 6-20V  Imax 18.7A
Link: https://product.mabuchi-motor.com/detail.html?id=129
Voltage regulator specs:
3x Pololu U3V70X Adjustable Step up voltage regulators
Link to Voltage regulator: https://www.pololu.com/category/243/u3v70x-step-up-voltage-regulators


texts: Why is inductive instead of capacitive power factor preferred?

texts: My question is why it is easier to correct an inductive power factor with a capacitor and not a capacitive power factor with a coil?


texts:
When trying to explain the need for high voltage in transmission lines, I came across a formula in one of my old courses:
A transmission line is considered, and between the generator end and the load there is a resistor \$R_k\$ and inductor with an impedance \$ X_k\$ modelizing the transmission line. The voltage drop across it became this:

\$ \Delta U\;=\; U_1 \;-\;U_2 \; = \; \frac{1}{U_L}\big( PR_k+QX_k \big) \$

I'd like to know where this formula comes from, I might not have searched enough but I have not found it so far...
Also, would it be correct to write the following:

\$ P=RI^2= \frac{U^2_1-U^2_2}{R}= \; \frac{1}{R\cdot U_L}\big( PR_k+QX_k \big)(U_1+U_2)\$
==> "To reduce transmission losses, current can be decreased, or the line voltage increased".


texts: Question about LDOs and the practicality of this application

texts:
I'll try and keep this as organized as possible so everyone can understand my thought process as easy as possible.

I will be using a 12V 5A switching power supply (available on eBay) to convert my wall outlet power down to a workable voltage. That will connect to a DC socket on my board
From there I need two different voltages: 9V at up to 3A for special LED's, and 5V at probably less than 1A for normal SMD LED's and a couple MCU's
I was thinking of using TI's LM1804 (http://www.ti.com/lit/ds/symlink/lm1084.pdf) LDO to regulate the 12V DC input to 9V for the special LED's, and then the ON Semi NCP1117 to get it down to 5V for the MCU's and LED's.
One of the other reasons I need an 8.5V+ supply is for the TI TPL7407LDR (http://www.ti.com/product/tpl7407l/description) to use as an LED driver for the special LED's. The IC datasheet makes it sound like it requires an input of 8.5V+ on the COM pin to be able to function at optimal speed and sink max current.

So here's what I'm curious about:

Is using an LDO like this a smart idea?
Would I be better off getting a 9V 4A switching DC adapter instead of a 12V 5A one (efficiency wise). I do need an excess of 3A as these LED's draw about 100mA's a pop, and I'll be running about 3A's worth currently. But I would prefer as much available current as possible due to future expansions that will actually draw up to 4-5A.
Can I use the NCP1117 5V LDO in series after the LM1084 9V LDO?
Should I need to use a rectifier diode before the inputs of the LDO's (for instance, like the Arduino does)?

I understand LDO's work by dumping the extra voltage and such as heat. I intend on using thermal vias and heatsinks. But in the case of the Arduino, for example, it takes a 9V to 12V 0.25A to 1A adapter and can safely and efficiently drop that down to 5V. So I feel like I've done a good job selecting components to stay as efficient as possible, and for not being a power expert, I feel confident this will work. I'd just like an outside opinion and some thoughts.

However, that TPL7407LDR is a tad confusing. If someone could clarify the COM pin requirements, I'd greatly appreciate it.

Thank you guys!


texts:
CW pumps out the full carrier but has a better SNR. On the other hand SSB suppresses the carrier, and one side-band but this suppression demands additional circuitry. There are probably additional considerations with SSB - poor SNR,  operator dialect but these are not part of the question here.

When the available options to transmit are CW, and SSB in ARES - which of the two will conserve the battery more?


texts: How can I use 24V DC input for Arduino digital pins?

texts: In this circuit, switches should be connected to 24V DC and arduino pins should check whether switches are on or off to control led behaviour. I don't know how to use 24VDC for this situation. I would be glad if someone can help. Thanks.


texts: Digital Design: Is there an elegant way to put a number in a sorted register file?

texts:
Let's say we have a module that has a register file currently inside that can hold 3 numbers. Suppose the three numbers are: 4, 6, 7. 4 is at index 0, 6 is at index 1, and 7 is at index 2. A new number, 5, comes in. The module has 4 outputs, where the numbers are always sorted.
The obvious way to do this is to have three comparators in cascade. The number comes in, gets compared with the first number, the bigger one gets propagated and becomes one of the inputs to the next comparator, and so on.
The above solution works, but since the comparators are in cascade, the speed is dictated by how many elements we have inside the module. Also, I feel this method doesn't exploit the fact that the numbers are already in sorted order.
Another approach is to use a shift register. But this requires us to use a clock and also wait one clock cycle since registers get updated one clock cycle later. This is supposed to be a combinatorial circuit.
I was thinking of a third solution where we would compare the number with numbers in the module at once. This would give us something like 0, 1, 1. We could then use this as the inputs to a cascade of multiplexers to numbers. I'm not sure if this is faster than the comparator cascade structure I mentioned above.
Any better ideas are appreciated.


texts: Difference Between Integral Time and Ki(Integral Gain)

texts: Can anyone tell me the difference between integral time and integral gain? I am really confused between these two terms and it's extremely important for the software PID for motor speed control I am developing.


texts: Share bypass capacitors with ICs or not?

texts:
I have a board which has many of the same IC MAX9611. According to the datasheet it should be bypassed by parallel 0.1uF and 4.7uF caps. Now I have like 15 of these right next to each other:

I am not sure if I need to solder all these caps for each and every IC. For one, maybe the capacitance of my 2 layer board (VCC pour top, GND bottom) will go to high and it maybe interfere with I2C signals? I have no experience with this configuration so I do not know what will happen in the worst case scenario... please shed some light!

I will read/write to each IC individually, so no 2 IC will be operational at same time.

I mean do I need to solder all the caps, or I can e.g. get away with having caps for each 2nd chip?


texts: How to reduce EM radiated emissions in a 2 layer board with 2 components?

texts:
Consider a 2 layer PCB with

Layer 1 is a signal layer (the traces in this layer are indicated with black arrows in the picture below)
Layer 2 is a ground plane, also called GND in the following (the return current path is represented in blue at low frequency, and in green at high frequency).
There are only 2 components: a source ic and a sink ic (target or destination). The common (GND) pin of the sink ic is in the lower left corner.
The signal being sent is a periodic signal.

what is the best way to minimize electromagnetic radiated emissions in this simple case?

My understanding would be that in this simple design, at high frequency, the current will take the path of least inductance (reactance) because the inductive reactance dominates the resistance component of the impedance of the return path. That path will be like the one in green, leading already to a small loop area (indeed the area would be the height between the two layers). To reduce the area further the best option would be to position the two ics as close as possible. Is this correct?


texts:
I saw many off-grid solar system designs are like this:

[PV modules] =(DC)= [charge controller] =(DC)= [batteries]
                       |(DC)|                     |(DC)|
                    [DC outlets]               [inverter]
                                                  |(AC)|
                                               [AC outlets]

The inverter use DC from the batteries. Will this cause the batteries charging and discharging at the same time, and shortening the batteries life?

Can the inverter connect to charge controller, and use DC from the PV modules without consuming batteries if PV modules provide enough power? The idea is just like this:

[PV modules] =(DC)= [charge controller] =(DC)= [batteries]
                     /(DC)/     \(DC)\
                 [DC outlets]  [inverter]
                                 |(AC)|
                              [AC outlets]

How do I integrate other power sources like the electrical grid (plugs), an electric generator, or a car engine into this design? Just connect them to the charge controller?

              [electrical grid]
                    |(AC)|
                  [inverter]  [car engine]
                     \(DC)\     /(DC)/
[PV modules] =(DC)= [charge controller] =(DC)= [batteries]
                     /(DC)/     \(DC)\
                 [DC outlets]  [inverter]
                                 |(AC)|
                              [AC outlets]


texts: Selecting proper bypass diodes for solar panel

texts:
On my sailing boat we've installed four solar panels (two times Vmp = 17.64V, Voc = 21.6V, Imp = 5.67A, Ioc = 6.07A, Pmax = 100W and two times the same but 75W), which we connect all in parallel, then to an MPPT system from Mastervolt which serves the 12V batteries and autopilot.
The solar panels are not exactly equal in voltage (Voc 21.6V and 21.2V) but in parallel that averages out. They're 2nd hand and were in working condition.
When we connected them in parallel, we accidentally had the system through the MPPT Mastervolt connected and all four minuses (3 panels, 1 Mastervolt) got connected with one solar panel's plus. Accidentally (we did inspect the voltage and pluses prior, but still screwed up). Then we connected the rest, all pluses (so we thought), saw a spark, disconnected, reviewed, and found that one panel didn't give voltage anymore. The bypass diodes (it had two) were burnt and split in two.

I read somewhere that short circuiting solar panels should not break them as the Imax can never get higher, but apparently we broke it anyway. This lead to some questions:

clearly these were wrongly connected, what happened here and why did it fry the bypass diodes? There was no shadow, current should not flow through the bypass diodes, right?
without bypass diodes, good panels should still give power, correct? [After frying, that panel gave zero on V meter. Is it possible one (of three) bypassable cells was already broken and the bypass was always in use?] Edit: this was wrong, they still have 20+ V.
these exact type schottky diodes are not available anymore, is it safe to select any diode with the same or higher specs (these were 80SQ045, rated 8A, 45V), as long as it is 'schottky' type? If I install two diodes in parallel (there's room), does that improve performance?
could it be burned solely because it's 10y old? The other panels seem still fine.

I tried to find answers to the above online and did find how these things are supposed to work, and that they break, but no info on how or why it breaks, let alone what happens when you screw up like we did. Hopefully someone here can help solve the mysteries or if not, help with the main question, selecting proper new bypass diodes.


texts:
I'm building an oscillator for a battery powered capacitive position sensor and I need it to have a high swing (>800 mV) at the output while keeping power consumption low enough. I'm feeding the output into the FPGA LVDS input so the oscillator must have a sufficient swing to drive it. Also it has to have large tuning range, a high ΔF/ΔC ratio and one side of the sensor must be grounded.

Right now I'm using a cascode Lampkin oscillator (see picture below), it has quite high sensitivity but it outputs only up to 600 mV into 4 pF load, consuming 2 mA at 3.3V.
I recently built a cross-coupled class D oscillator and I got 3 times Vcc at the output while consuming only 1.2 mA! But it's a differential oscillator so I can't use it because the probe is not differential and it can't handle the whole possible capacitance range. I also saw a class-C Hartley oscillator that has higher efficiency by the looks of it but I don't quite understand how it works and how to change the circuit for my application.

So is there any oscillator topologies that are more power efficient than the one I'm using and still sensitive enough to capacitance changes?


texts: how to reproduce a matching network of a vendor

texts:
I'm trying to create a board using the BGT24MTR chip from infinion. I noticed that they said that there is a Tx/Txx impedance.

To compensate for this impedance they created a matching network.

Since I'm trying to use a different board stack up, I have to redesign this matching system. I tried calculating the impedance of each of the lengths

Here's my breakdown of the major components.

Width Length  Ω     diff Ω   diff Ω single
.3    .55     68.5     82     61
1.15  1.6     31.19    22.2   16.5
.5    ∞       53

I thought that I was trying to use the smith chart to get the impedance to be purely real around 5/3 after the second rotation so that when it is renormalized it would be purely in the unit circle in the center, but every way I looked at using the smith chart led to results that are far away from being matched.

Any suggestions on what they are doing to match this?

P.S. The new board stack up is FR408 1.6mm thick. 1oz copper on both sides (1.4mil,35um). Frequency is 24 GHz


texts: Band-pass filter with a given impulse response (Matlab)

texts:
I am trying to pass a .wav sound waveform through a band pass filter whose impulse response is given by

\$ h(t)=50u(t) \exp(-10t) \sin(2 \pi 440t), \$

I have imported the file into Matlab as follows:

[s, Fs] = wavread('piano_chord.wav');

So, what syntax do I need to use to implement this filter?

I have looked at the [b,a] = butter(n,Wn) or [b,a] = cheby1(n,Rp,Wp) for Butterworth and Chebyshev band-pass filters respectively. But I don't know how the equation for impulse response factors into this, and what values I need to use for a, b, and Wn.

Any help would be greatly appreciated.


texts: Why does 'in-circuit emulator' contain the word emulator, if nothing is being emulated?

texts:
Doing a quick read up on in-circuit emulator (ICE) hardware, I'm confused as to why the word 'emulator' is included. It sounds like most ICEs are just fancy chips that can control a processor for debug purposes. However, it seems like nothing is being 'emulated'.

Why is this?

Edit: I'm specifically referring to this Analog Devices 'ICE' here.


texts: BLDC Commutation and output states of half bridges

texts:
I am trying to run a BLDC motor using TI DRV832.

In the datasheet, there is the following truth-table, where I do not know what are GLx, GHx and SHx. Also, what does Hi-Z do?

I want to control the bridge directly, so I assume the bridge is something like this:

I think I only need to set GLx and GHx into H and L states and no Hi-Z state is needed. Is this the correct assumption?


texts:
I am developing an high current dc motor driver, and I'm looking for mosfets that can dissipate enough power without heating too much thus without using heatsink.
I saw this project : http://navrobot.blogspot.it/2014/12/high-current-dc-motor-driver.html
but I made some calculations and I found out that the maximum current that can flow without heatsink is around 3A.
Do you know any mosfet that can deliver enough current (about 20A) for my project?


texts:
Suppose i have 2 non-blocking statements as follows:
    reg x,y;

    initial

    begin

    x=10;

    y=20;

    end

and if I execute this:
a)
always @(posedge clk)

x<=y;

always @(posedge clk)

y<=x;

So will the values of x and y get swapped or will there be race condition here? (suppose i print the values in the 2 blocks, right after the assignment). Also will the always blocks run independent of each other?
and what's the difference if I do this:
b)
always @(posedge clk)

begin

x<=y;

y<=x;

end


texts:
My task is to control 64 LEDs with a 16-output drive. The control of each LED must be individual, that is, the activation of one LED must not interfere in the functionality of another.
I'm using an MBI5039 drive that sends a negative signal to activate the LED.
I thought of an 8x8 matrix where I can control rows and columns. For example, to turn on LED D0, I must activate the outputs OUT_0 and OUT_8.
When I want to turn on LEDs D0 and D1 at the same time, I must activate the outputs OUT_0, OUT_8 and OUT_9.
Now when I want to turn on LEDs D0, D1 and D10 I must activate the outputs OUT_0, OUT_1, OUT_8 and OUT_9. However, at that moment something happens that I don't want: LED D9 is also turned on.
I would like to know if there is any way to make the independent control of each led using matrix. I would not like to have to use a multiplexed circuit.
Note: I know the need for passive components (resistors) for the correct operation of the MOSFETs. The image circuit serves only for a logical explanation.


texts: Violin bow position tracking with SMD LEDs and photoresistors

texts:
Objective:
Marking labels indicating the positions of the violin bow on an acoustic signal, for example, a single musical note played by a full-length bow. The following video shows the example I am talking about, please just take a look from 1:00 to 1:03:
https://www.youtube.com/watch?v=XIKPHsVyxKs

If divide the bow into three parts with equal length, roughly two markers can do it. So what I want to do is put those two markers on the corresponding acoustic signal, like this:

The objective is to figure out "oh, at this and that moments, the bow has traveled 1/3 and 2/3 of the whole length, respectively" when looking at the acoustic signal.
A naive way is to simply divide the time axis of the acoustic signal by three, but it cannot be assured that the velocity of bowing is constant.

Method: According to the article http://www.ubicomp.org/ubicomp2013/adjunct/adjunct/p211.pdf which used a pair of colored SMD LEDs (as emitters on the bow) and color sensor photoresistor (as receiver on the violin) to tackle the problem. However, the circuit and the explanation of figure 3 are not clearly described, which made a lot of problems for me.

Problem:
In short, based on my understanding, by installing SMD LEDs with different colors on the bow (red and blue marks in the case of the above figure), and a color sensor photoresistor on violin which detects the time-varying voltage when illuminated by SMD LEDs on the traveling bow, the objective described in the first place could be achieved. The following figure explains the idea:

So the peaks in the figure indicates the positions of both LEDs. By aligning the time-varying voltage and the acoustic signal, the objective shown in the first figure is solved.

1. Is the above statement correct, achievable or not?

2. If so, how to set the circuit on both two ends (emitters and receiver)?

I am fairly unfamiliar with hardware and electrical components, hope you can help me if possible, thank you very much!

EDIT:
I've implemented the LEDs and photoresistor as detector, and it works as I desired. Here comes the other problem: the alignment of the recorded audio signal and the time-varying voltage detected by the photoresistor. What came to my mind is a acceleration-sensed LED installed on the driving point of the bow, which makes a blink at the moment the player drive the bow. The idea is to blink the LED once the change of the acceleration direction is detected by a component. Such change in acceleration direction will thus make a impulse on the displayed time-varying voltage which indicates the onset of the audio signal.

How could I achieve such acceleration detector combined with a LED, with an acceptable size to be installed on the violin bow?


texts: VT vs RVT capacitors : what do they mean?

texts:
I see on these two products which have the same function (and obviously also the same construction, these are switches which allow to activate/deactivate individually the power supply of one or more hard disks in a computer), that some use "100 16V VT" capacitors and others "100 16V RVT" :
https://www.amazon.fr/chenyang-Syst%C3%A8me-contr%C3%B4le-Intelligent-Disque/dp/B0816F5HX4
https://www.amazon.fr/KSTE-Commutateur-S%C3%A9lecteur-Switcher-Ordinateur/dp/B082D7GY6J
I don't find anywhere an explanation for the difference between these two VT versus RVT markings.
Could you clarify the meaning of these 2 acronyms to me, and above all, their differences ?
Thank you.


texts:
We have to find the output impedance of the following circuit, where the output is the upper pin of R4. If I try to compute it with LTspice, I get about 55 Ohm, but whenever I try to work on it theoretically, I get 77 Ohm, and I don't know what I'm doing wrong.

For the theoretic approach, I replaced the BJT with the T-model. I've asked a few other people, and we all get about 75 Ohm, if we replace with the T-model.

Edit: For the LTspice simulation I used the following circuit, to compute output impedance:


texts:
I want to measure micro volt signal from 10 micro volt to 1000 micro volt. for this i have used ADA4528 IC. And used three Op amp in series, first as voltage follower, second as amplifier of gain 10, and third as amplifier having gain 100.
Is it okay combination for micro volt measurement? Or instrumentation amplifier will be good for micro volt measurement?


texts: How can i find total power consumption of the device from its datasheet?

texts:
In datasheet which parameter should I consider as a power consumption of a device?
What is Icc?
what is Iin?
To get total power consumed by device can I multiply input  current Iin with input voltage Vin.
          P= Vin*Iin ?

Is this correct?

Only study the datasheet is enough to get the power consumption of any device?

Thanks!!


texts: Why is there a voltage drop across the load resistor in an ideal diode clamper circuit?

texts: Consider a clamper circuit with an ideal diode, a capacitor, a load resistor and an AC input supply. When diode is in forward bias configuration, it must conduct and behave like a short. We must then get zero voltage across load resistor. Then why do we get a voltage drop across the load resistor?


texts: Please identify this burnt out SMD component

texts:
I hope to repair a p.c.b. for a hard disk drive, which has a burnt out SMD component (by mistakenly connecting the supply back to front -- I had to guess and got it wrong), 2010 size, a connection at each end, with a polarity(?) line at one end . It has "ON" in a circle, and "QA" and "R 846 ." written on it.

I have searched on line with no success, so please can anyone identify this component?


texts: Effect of the high impedance or low impedance of oscillospe

texts:
I am measuring a sine waveform range 0 to 40MHz by using Agilent InfiniVision DS0-X 3034A. The data sheet of the oscilloscope is here: http://cp.literature.agilent.com/litweb/pdf/5990-6619EN.pdf

My question is when do we need to use low or high impedance setting of oscilloscope and why?  I know that high impedance will give less distortion on the waveform, but why it will give less distortion?


texts: What material should I use to insulate my MOSFET from a heatsink?

texts: I have a heat-sink and I want to put two FET's on it. I know I have to insulate it so the metal showing on it doesn't connect and create a path. Is there any good everyday material that would work? (ex. plastic bag)  My packaging is TO-247 (irfp250/450) and I found 1 insulator laying around, but not 2 for both of them. So do I need to put the insulator on both MOSFETs or is one good enough?


texts: Writing to and reading data from Flash using IAP

texts:
Here you can see functions I'm using to store data into Flash, but I'm getting data erased after power reset, so it's still in RAM not in Flash.

#define   OFFSET_ADDRESS                     0x00030000
#define   OFFSET_VERSION                     0x00030002
#define   OFFSET_SERIAL                      0x00030004

    void read_from_flash (void)   {

        BYTE i, *pok_add, *pok_ver, *pok_serial_no;

        pok_add = (BYTE *)OFFSET_ADDRESS;
        display_address = *pok_add;
        delay_1_ms();
        if ((display_address > MAX_OUTDOOR_DISPLAY_ADDRESS) || (display_address < MIN_OUTDOOR_DISPLAY_ADDRESS))  display_address = UNI_ADDRESS;

        pok_ver = (BYTE *)OFFSET_VERSION;
        version = *pok_ver;
        delay_1_ms();
        if (version > MAX_FW_VERSION)        version = 0;

        for (i=0;i<8;i++)     {
            pok_serial_no = (BYTE *)OFFSET_ADDRESS;
            serial_no[i] = *pok_serial_no++;
            delay_1_ms();
        }
        for (i=0;i<8;i++)         if (serial_no[i] > 9)   serial_no[i] = 0;

    }

    void write_to_flash (void)    {
    BYTE i;

        iap_copy_to_flash(&display_address, OFFSET_ADDRESS, 1);
        delay_1_ms();

        iap_copy_to_flash(&version, OFFSET_VERSION, 1);
        delay_1_ms();

        for (i=0;i<8;i++)     {
            iap_copy_to_flash(&serial_no[i], OFFSET_VERSION+i, 1);
            delay_1_ms();
            }

        }

Question is where I'm wrong? Sectors in a LPC178x/177x device http://www.nxp.com/documents/user_manual/UM10470.pdf on page 883. Maybe I don't write and read data properly so it's still located in RAM.


texts: Math of capacitor current/voltage when connecting capacitor to battery

texts:
I think I'm missing something fundamental in the math surrounding capacitors.

Suppose I have a 1 F capacitor that is not charged.  The voltage across its terminals is 0 V.

Now suppose I connect a 1 V battery to it.  The voltage across its terminals is therefore 1 V.

The current to it is given by:

I(t) = C dV(t)/dt

But the voltage has jumped in a non-continuous manner from 0V to 1V.

Therefore dV(t)/dt is "infinite" (or undefined) at the time t where I connected the battery.  It jumped from 0V to 1V "instantaneously".  This implies the current is infinite at this point.

What am I missing here?


texts:
I'm designing this low pass filter after the OpAmp AD8607 and i read that this stage can affect the stability of the amplifier. The example said the stability was dependent on the time constant of the filter but it didn't say in which way.
Can someone explain how is dependent or what information in the datasheet can help me to guarantee the stability ?
Thanks.
I


texts:
I'm interested in flashing a firmware to Macronix MX25V8006E externally, before placing it in the SMT process.
This SPI is an external SPI flash for a PCIE to USB 3.0 adapter board which uses VL805-Q6 Host Controller. I couldn't flash this SPI using VIA-LABS update tool for the first time (through the Host Controller). I had to use DediProg programmer for flashing the SPI externally for the first time, then I was able to use their Update Tool in order to update the FW version, or read the current one.
since using Dediprog through soldering some wires is a very tedious work, my company will face problems in producing this board in large quantities.
We are looking for a solution to flash this SPI in the easiest and fastest way possible (also a solution that doesn't use a PC is welcome).
Note: I have the required FW needed for the device to work.
is there any developing set or a device on which we can manually place the SPI flash and program it?


texts: Why are fieldlines getting distorted near a conducting sphere?

texts:
Is the total flux of an electrical field through a conductor always zero because of Gauss`law? Does this cause the field lines to diverge, as they would offset the equilibrium? Quote from here:

But, since the total flux of the electric field through the horizon must remain zero, in addition to "ingoing" field lines there must also be "outgoing" field lines. This situation is somewhat similar to a charge near a conducting sphere: there are induced surface charges, with the charges of the opposite sign localized on the surface part closest to the external charge but the net total charge of the conductor is zero.


texts: KCL equation considering the leakage current

texts:
simulate this circuit – Schematic created using CircuitLab

In the schematics shown here I want to find out the potential at Va and Vb nodes with assuming a constant leakage current Ileak flowing at node Vb.
I want to write KCL equations for the nodes.
To start with for node Va : (Va-V1)/R1 + (Va/R4)+(Va-Vb)/R2 = 0
                  node Vb : (Vb-Va)/R2 + Vb / R5 - Ileak + (Vb-V2)/R3 = 0 and for leakage current I considered the superposition theorem and got Ileak=Vb/((R6||R5)+R2)||(R6||R3)); I am really not sure how to go ahead writing the equation taking the leakage current into consideration..


texts: Arduino vs standalone microcontroller programming

texts:
Arduino is great to program and use. But if I need to produce standalone microcontroller (e.g in the case of manufacturing a device) I guess I need to know PIC programming, C language, programmer kit etc.

1) Arduino is not using C.

2) Using Arduino board I can not program any PIC microcontrollers

My question is that if I make a device and can not use Arduino for the ultimate goal, does it means that I also have to learn PIC programming and many other aspects? Is Arduino just for testing your ideas rather than implementing them for standalone use?


texts: What is this weird EMV pin on my credit card?

texts:
I recently got a Venmo card, which is my first card with contactless support. I was looking at the EMV pins and noticed a very weird design. In the middle of the ground pin, there is this long, thin pin extending into it that I've never seen before.
It has ~5 MΩ between it and the ground, so it doesn't seem like just an aesthetic feature. What does it do (and why isn't it on most cards)?


texts:
I got a RAM-DAC with 3 channels and 6 bits for each channel. The device in question seems very straightforward to use with a modern MPU like an AVR.

The resolution is a bit low, so I thought about cascading the three channels with a R-2R-ladder. Does that work with current-output-type DACs?


texts:
I want to drive a servo rc motor I just purchased, I am a newbie in the electronics world.

I would just like to test out the servo motor first and actually get it to move.

So far I have figured out I need a basic diagram for the circuit, I have consulted the servo motor data sheet, I know I need an oscillator, some transistors, a breadboard and a micro controller, not sure what else yet.

It is possible to drive it without a micro controller right?

I will be using the amicus micro controller.

Any suggestions?


texts: Source of a NP 47µF 60+V capacitor for audio?

texts:
I am building a preamp which calls for a 47µF 60+V capacitor. It needs to be non-polar and being audio low ESR. (Yes, this is a 1NA217 based circuit.) The circuit requires NP caps if phantom power is not to be used. Although I am certain I do not need such a high voltage capacitor without phantom power, I may add phantom power in the future and would like to avoid having to switch out capacitors.

I need something affordable but good quality. The Nichicon aluminum organic polymers seem to be great for the price but they are polarized... I could use 4 (pair them in parallel to double the capacity, then in series (negative to negative) to make non-polars.)

Space really isn't a limitation, and although I see no issue with this technically, it still gets kind of pricey using 8 capacitors instead of the 2 the circuit requires.

Is there a better way to get NP 47µF 60+V caps with low ESR? I have searched quite a bit and I cannot find any affordable capacitors at these specs.


texts:
I don't know why, but everytime i or someone on the room next door switch off lamp, there is a loud pop coming from the speaker.

1) is that behaviour are caused by my amplifier (diy)(the line in cable doesn't have shielding,just 3 wire)

2) improper build of electrical installation in the building itself

3) my adaptor is bad? (i think it's just have big cap, resistor and 4 diode and a transfomers,the case is quite transparant though)

And how can i resolve this thing? Because it's quite annoying
the noise is present whether connecting to laptop/phone or not


texts:
What is a high impedance low level signal?

(I'm reading the circuit designer's companion by Peter Wilson)


texts: Can I use a roostick, which contains FTDI chip to program my arduino chip?

texts:
I bought a Roostick from here, I believe this uses the FTDI chip. Most recently I bought an Arduino parts kit to learn about the Arduino board here. One of the ways this board can be programmed is using an FTDI cable available here.

I believe the Roostick and the FTDI cable use the same chip for the USB to UART conversion. The Roostick has a breakout pins for Gnd, R_DD, R_TXD, R_RXD and 15.6V. My question is, if I could use the roostick to program the Ardunio directly in my Breadboard kit. I am guessing I would have to hook up the Gnds together and swap the R_TXD and R_RXD between the Rootstick and the Ardunio. but the 15.6 Volts on the roostick bother me.

If I hook this up, would this fry my chip?


texts: How can I program a STM32 Nucleo board without using the on-board ST-LINK?

texts:
I don't have any prehistoric mini-USB cable and nor can I find one in nearby stores. The board doesn't come with one either. Can I still use my Nucleo board? How?
I should add that I have a STLink V2 programmer. Can I use that to directly program the Nucleo board?
Edit: It worked using the answer below. I'm adding this in case anyone else tries to do this: it works for me ONLY when I connect BOTH the 3.3V and 5V properly. Otherwise, the GPIO logic levels are messed up and no peripherals work. Sometimes the board itself refuses to be programmed as well.


texts:
I have a question regarding the impedance of voltmeters. I learned that a voltmeter can be modeled as follows, where \$R1\$ is the input impedance:

simulate this circuit – Schematic created using CircuitLab
I noticed that many multimeters have a \$10\,\mathrm{M}\Omega\$ input impedance on the volt range (some even more) and wondered where the (often well defined) input impedance exactly comes from. Is it coming from the ADC?


texts: Reading bookshelf contents using RFID tags on books

texts:
I apologize if I make a grammar mistake...
I'm a telecommunications engineering student and I have an idea for my grad project. It would be something like a SmartBookshelf.
My idea is to implement a system on a bookshelf capable of knowing all the books that are on a bookshelf (is not necessary to know where exactly in the bookshelf they are, just that they are there). There will be other things, like a web page on which people can see their books and info about them, and a message will be sent by email if a book gets far from the bookshelf.
I thought about using RFID sticker tags on every book, and a scanner that knows if they are close using them. I'd like to know if there are affordable RFID scanners that can detect tags to at least one meter distance.
I found out about the 13.56MHz RFID Reader SL500, which looks affordable but I can't seem to find any info about it's range.


texts: I have a very basic question about the termination resistor of the CAN Bus. I know that a termination resistor is needed in order to avoid unwanted reflections. Since the characteristic impedance of a loseless line is defined as $$Z=\frac{L'}{C'}$$ and the inductance as well as the capacitance is depending on length, I am asking myself why the termination resistor of CAN is always recommended to be 120 Ω. Shouldn't it vary for Highspeed- and Lowspeed-CAN?


texts: 50kW-100kW motor: BLDC or induction and why?

texts:
My friend and I are doing a sort of academic research about heavy electric vehicles. A sub-project involves choosing the wheel motor and defining the control method.
Aside from what currently exists on the market (this is academic research) we are interested in debating why one solution is preferred above the others (or the pro/cons of each one.)
The main design requirement is the motor power: 50kW to 100kW.
The other important factors for the motor are:

Construction complexity
Reliability
Weight
Price

For the control unit:

Reliability
Weight (e.g. due to big heat sink)
Price

Currently, modern technology pushes towards BLDC but we need to explain WHY it is better than other alternatives. We currently considered as a possible alternative an AC motor + inverter (or induction motor?)
My questions are:

What are the pro/cons of one compared to the other?
In case of AC motor + inverter, could be the inverter be a PWM generator and using the engine coil as low pass filter to optimize everything? yes/no/WHY?
Can you please provide reference literature? I investigated myself but most are just one page sheet which just tell the generic stuff about this or that.


texts: Arduino in Ground-Chassis (Vehicle): Activate by grounding

texts:
I am working with an Arduino as a controller for an Aftermarket Heated Seats Kit and interface for the stock A/C Auto Control Panel (the car did not come with heated seats, and I acquired an A/C Panel that has the LEDs and buttons needed).

To turn on the LEDs, all that is needed is to ground the respective wire to the chassis of the vehicle. But because of the way they are wired (the LEDs receive power when the vehicle is running) there is about 10v (estimate) sitting there looking for the least resistant path to complete the circuit.

This could be pictured as such (resistor value is not real value):

In this circuit, like most circuits in modern vehicles, once the LED is grounded, it activates.

This brings me to my question:

Can an Arduino be used to ground this circuit, without relying on a relay, with a transistor or similar (having the transistor ground the circuit instead) when an OUTPUT pin on the Arduino is set to HIGH, or LOW?

And if using a transistor is possible, how can I figure out which one I need for this application?

Taking into consideration that most Arduino don't provide a lot of current on their pins (for a high amount of LEDs), how many LEDs can be turned on, at the same time (its max load), until a typical Arduino UNO will burn out, using a transistor - how can you avoid doing burning it out?


texts: External power supply design - Audio Microphone preamplifier . AC vs DC

texts:
Any outstanding pros and cons of transmitting over short distances (1-2 meters) AC vs DC?
Details: I wish to move the power transformer from a micpre into a small external enclosure to eliminate hum pickup in the device. I could build the entire DC supply in the external enclouser or just send the secondary of the transformer and keep the DC as is; in the device. Any drawbacks to sending the AC voltage? It would be just +/- 20vac and ground of course.


texts: Why is the 1uF capacitor needed in this load-sharing circuit?

texts:
Consider the following circuit that describes a MCP73831 battery charger with a load sharing circuit:

Why is the 1uF capacitor needed? I realize that the 4.7uF are there to reduce "noise", but why the 1uF? Why this value in particular? Why would I decide such thing in my circuit and how would I come up to this value?

P.S.: Could it be to attenuate the switching time of the MOSFET when the USB is disconnected?


texts: Input impedance of High - Frequency Amplifiers

texts:
I have a question about the choice of the input impedance of a high frequency amplifier.

In general I know from elementary analog electronics courses that it is good for an amplifier (for instance an Op - Amp) or in general for a voltage meter, to have a very high input impedance. In this way, there would be only a negligible voltage drop on the parasitic resistance of the source, and so no signal loss.

But this seems to me in contrast with the design of RF amplifiers input impedance. For instance, let's consider this circuit of a logarithmic amplifier which works at frequencies between 1 MHz and 8 GHz:

The designer put at the input a parallel resistance (R3) of 51 Ohm in order to realize the impedance matching with the signal generator (which is supposed to have 50 Ohm output impedance) to avoid reflection. But it is completely in contrast with the previous criterion.

I have a similar doubt about the output impedance of a device: in radiofrequency circuits I see that it is chosen to be equal to the input impedance of the following stage, while in analog electronics courses I learnt that it is important for it to be equal to 0 (or anyway it must be very low).


texts: Eagle CAD: PDF scaling problem? (tone transfer method)

texts:
First of all, how do you export your layout to PDF in order to create the PCB using tone transfer method?

In the past I created one small PCB by doing the following: print > PDF format (scale=1). No problems.
However today I installed Eagle (5.11), tried to do the same but, after the PCB is created I found that I got a scaling problem in my hands. Headers don't fit in holes! I tried to export PDF with different (virtual) "printers" and, with SmartPDF I got the best result. However still doesn't fit perfectly with headers.

Thus, I tried "Cam Processor" with "layout2.cam", exported layout to an EPS file format and printed that. Now the holes fit perfectly.

How do you export layout to PDF when using tone transfer method?


texts:
I have been working on this problem and it is driving me absolutely crazy. The questions is asking for Vo for time greater than or equal to 0. I have successfully redrawn the circuit (shown below) to represent steady state or t = (0-). This gives me an initial value at Vo of 12 volts. However, I cannot come up with a set of equations after the switch is open.

I feel like Nodal Analysis should work in this situation but I keep ending up with 2 equations and 4 unknowns. For example:

1: (Vo - Vx)/20k + C1(dVo/dt) = 0

2: (Vx - Vo)/20k - C1(dVo/dt) + Vx/40k + C2(dVx/dt) = 0

No matter how I approach the problem I end up with a differential from the other capacitor! I have no clue how to approach this problem. In addition to the madness I am not sure if my C1 is correct in equation 2.

Can someone please help me or give me some direction on how to solve the natural response of the circuit below (The third image)? Thanks for reading.


texts:
I'm trying to build a Bi-Directional buck-boost converter. The input should be between 9-12 and output should be 12. Can any one recommend a good topology to follow. I also have a few conceptual questions. If anyone can recommend good topologies to follow along with a good chip I would really appreciate that.

Are all buckboost converters bi-directional?
Do i still need transistors for the switches? Or will the chip do the switching for me.


texts: I'm looking for help designing a circuit that lights LEDs in response to physical output on a small electric generator

texts:
I made a little display for kids that various non-profits have been using that helps them understand how much electricity different kinds of lightbulbs use.  It's very simple, using bike parts to drive a 350 watt electric generator the kids can feel the resistance of each bulb as they flip the LED, CFL, and on and off.  Everyone loves the display, and so far it has been pretty resilient, but there are several things that have been causing it problems that have me interested in changing the electronics behind it while keeping the mechanical design the same (I'm a mechanical person, not an electronics person).

There are two phases to this.  The first is hopefully a simple fix to solve the biggest problem with the current display, if a grownup or super excited kid goes all out on it, occasionally they can burn one (or all) of the lightbulbs out.  Right now the voltage is only dictated by the gear ratio, if someone gets above 180 rpm they can spike the voltage and start killing things.  I was hoping there was a little something I could put onto the existing display that might divert the electricity once all three of the lightbulbs are sufficiently lit so that they never see the voltage spike that kills them.  If there is a simple solution here I would love to hear it.

Phase two is a redesign of the display.  After watching people interact with the display it's pretty apparent that people treat it more like a carnival test your strength exhibit than a nice little interactive display, which got me to thinking about those sledgehammer test your strength things you see at carnivals.  The idea is that instead of having switches to turn the lights on an off, you would just have a vertical board of lights, LED at the bottom (easiest), then CFL, then Incandescent, then maybe a hairdryer or a siren or two incandescents... what they are powering isn't really important, I'm just trying to understand how complicated it would be to make a circuit that will switch between the various loads as the user ramps up the RPMs, and if it is something that I could put together as a novice to circuit-making or if I should seek outside help.  I'm fairly good at soldering, and probably have all the technical skills I need to do this, I'm just lacking in the information department.

I have tried to find something similar to copy online but I don't know enough of the terminology to get as specific as I need to.  I have a vague idea of linking together comparator circuits and resistors to simulate the increasing voltage and using LEDs for everything so the load is standard between steps.  Also it seems like integrated circuits might be a good option, but I have no idea where to start there.  There is something really desirable about the direct link between powering the bulbs and pushing the crank, so if it's possible that would be a nice touch to keep.

I hope that this is all very clear, I appreciate any help people are willing to give, or any ideas that are variations of this that would be a little more hardy electrically.

Thanks in advance,
Mark


texts: How can I sense if a cane is being held upright or fallen down?

texts:
I am trying to make a little wireless-connected gizmo to attach to my grandfather's walking cane. The idea is that when it senses the cane has fallen down, it would alert/call one of us so that we can rush to him if we're not nearby.

The question is: What sensor or combination of sensors could I use to reliably differentiate between these two scenarios?

NORMAL situation: The cane is being held upright (or at only a slight angle from vertical) and used normally.

versus

CRITICAL situation: The cane has been let go of, falls down and continues to lie on the floor/ground

Obviously, occasional false positives would be fine, but detection misses (false negatives) should be minimized.

I am thinking a combination of two things might help:

--sense whether my grandpa's hand is holding the cane or not (perhaps a light sensor that is blocked when the hand is on it?)

--sense whether the cane is upright or has taken a fall (perhaps an accelerometer+gyroscope+vibration sensor to determine orientation and shock events?)


texts: Examples for AC circuit analysis with AC voltage source in parallel with DC current source?

texts: Where can I find examples of AC analysis of circuits with AC voltage source in parallel with DC current source and resistors? I could only find examples involving capacitors and inductors.


texts: Help with LTSpice full-wave rectifier simulation

texts:
I'm fairly new to LTSpice and its function. Our professor asked us to construct this specific circuit (in the photo). I tried doing it on my own, but I am not that confident if my LTSpice circuit is the same as the one that is instructed.
Note: Our professor only taught us the basics of LTSpice, like how to put different components etc.

The photo below is my attempt:

May I ask if I should change anything in my LTspice simulation or is it already correct? I also do not know anything about potentiometer or even oscilloscope. Those two terms are fairly new to me.


texts: How to specify castellations in gerber files

texts:
I am making gerbers where I want one edge of the PCB to have castellations ( plated half-holes) on the edge.

What is the safest way to specify castellations in the gerbers that will ensure that:

The fab how makes the castellations "properly", without making any mistakes. For example one possible mistake is that if the castellations are specified as vias chopped in half by the edge, then a CNC router cutting the board edge may tend to rip the copper off of the castellation through its high-speed spinning motion.
The flat edge itself must be plated - not just the hole part!! See how the flat part of the edge is supposed to be plated in the vicinity of the hole:


texts: How can I reset all part names in Eagle PCB?

texts:
I've built a large PCB, which merges about 17 schematics. There are about 1000 components on the board.

What I need to do now is rename all of the resistors and capacitors. Currently the parts are named R1, R2, etc, and I want to reset the names to G$1, G$2, etc. so I can rename everything with the correct part numbers. Is there something built into Eagle to rename all of these components?

I've searched through Eagle's ULP scripts, but I can't seem to find one that does this.


texts: How do I connect the certral pad of a QFN24 to the Ground in Kicad?

texts:
I need to connect the central pad of the QFN24 to the ground

I got the package from the library that came with the Kicad (libcsm).

I tried to edit the module and assign this pad to a number, then I connected it to the ground in the schematic and regenerate the netlist, but it complains about the round-yellow pads (see the image below) that overlaps the square-pad.

What these round-yellow pads are? Can I remove them?
When I tried to edit these pads, it says that they are "NPTH,mechanical" types, what this means?

Thanks for your help.


texts: I'm trying to convert +/-12VDC to +/-24VDC to power a DC motor in both directions. I've tried using a step-up converter like this one, but when I feed it -12VDC, it doesn't output anything. Is there an electrical component that will output +24VDC when fed +12VDC and output -24VDC when fed -12VDC? Total noob here just trying to motorize a skylight with a chain actuator, so please excuse my limited understanding.


texts:
Taken from the datasheet Pg. 186 "When VBUS sensing feature is enabled, PA9 and PB13 should be left at their default state (floating input), not as alternate function. A typical 200 μA current consumption of the sensing block (current to voltage conversion to determine the different sessions) can be observed on PA9 and PB13 when the feature is enabled"

I'm not too sure what this means - will it draw 200 uA from PA9 and PB13 when the USB is plugged in ? Right now I have PA9 connected to VUSB, but PB13 connected to an ethernet TXD signal (Unforunately I don't think I'll be able to move the signal to the other place where it's offered - PG14.

I've made my design in STM32CubeMX and it seems perfectly fine (all greens).

Will it be ok to leave PB13 connected to the ethernet signal ?

Thanks in advance!


texts:
I need help with USB CDC communication with PIC18F4550, xc8 compiler.

I downloaded that files on this link: http://www.microchip.com/forums/m679588-p2.aspx

It works, but doesn't have all the files, like main.c. Is there someone that can give an example?


texts: How to choose current sense resistor and current sense Amplifier for precision sensing

texts: While measuring current from 0A to 500mA with 10uA step, I am using current resistor, current sense amplifier, 16-bit ADC.How do I choose current sense amplifier and current sense resistor


texts: Line following help with acute and right angles

texts:
I am trying to figure out the logic for a line follower with the path shown in the attached image. I am having trouble with <= 90 degree angle turns. So far, I have been using the logic where if the middle and a side's sensor are on the line and the other sensor is on white, then I turn 90 degrees after driving forwards a little. This does not work for the part marked in blue since the distance designated by the arrows is too small to drive forward any amount and the acute angle causes my car to keep going side to side perpetually half the time I run the program.

Also, if I am using proportional line following in order to approach intersections more perpendicularly, do I have to keep track of which side of the line I am on?

Suggestions on how to improve my design would be appreciated


texts: Best XLR cable and metal for home use & vocals?

texts:
I am very lost on what the recommended XLR and also the what the recommended type of metal connector is for sound quality as many say completely different things such as Silver being more conductive and more transparent with Gold being more durable and warm sounding etc? I only record at home in a small room with only my voice so I am lost on what to go for? Copper, Silver, Gold, Platinum or other or a hybrid of sorts?

My current cable is a LyxPro Balanced Gold XLR Cable.

My microphone is an sE X1 S which has a gold connector on it if that info is any of relevance?

Edit I also almost never unplug my XLR cables if that is also any of relevance?


texts: Why a PMOS active load is used for a NMOS common source amplifier?

texts:
let's consider this NMOS common source voltage amplifier with active load:

For small signals the PMOS transistor M2 acts as a resistor of value \$\frac1{g_{mP}}\$ (P stands for PMOS) and so the voltage gain of this amplifier will be:

G = \$-\frac{g_{mN}}{g_{mP}}\$

I have been told that in some IC it is not a good amplifier because it has a big sensitivity to temperature variations, since \$g_{mN}\$ and \$g_{mP}\$ change differently with temperature and so their variations are not balanced. It would be a better option to get a gain which are expressed as ratios of similar physical quantities.

So my question is: why not use always a NMOS transistor as active load? Something like this:

I'd say it will work exactly in the same manner. But I have always (or almost always) seen the amplifier with a pmos active load. Also in differential pairs, I have always seen only pmos active load for nmos amplifiers:


texts: closed loop zero in second order PLL with a proportional-integral filter

texts: Why does the closed-loop zero in second-order PLL with a PI filter enhance the phase noise near PLL bandwidth frequency? I know that it enhances the phase margin but i can't find the logic behind why it enhances the PHASE NOISE and also that why this zero causes the 'continued increase in phase error' even when the feedback is trying to correct it??? and also why don't the DLLs have this problem of 'jitter accumulation', in other words?


texts:
I am an IoT solutions developer and not an engineer, so please excuse my vocabulary if not upto the mark.

I have used Mosfets such as FDD6637 and IRF9310 in my circuits for power switching and they work great for my use cases because of their low Rds(on).

From the datasheet, there is an internal diode and I am showing the characteristics in the attached image.

My questions:

What would be the internal resistance of this diode?  Will it be the same as Rds(on)? I can't seem to find it in the datasheet.
Do you know of any P-channel mosfet that does not have this diode but has similar Rds(on) (10 to 15 mOhms at -4.5v?).  I do not want reverse current to flow in a particular case, as I need my switching to work in only one direction.

Thanks in advance for your help!!

EDIT:
I have shown my problem in the rough diagrams below (sorry if the symbols are not accurate).

Works but battery powers load through internal diode (apparently):

Even though above circuit works, the question is about the internal resistance of diode and the drop across the mosfet when main power is off.

Following does not work because main voltage shows up at battery connector:

In the above circuit, I expect the mosfet not to conduct when there is +9v. But it is conducting because of the internal diode. This circuit would take advantage of the low Rds(on), so it is desired.

When there is no +9v, the load gets powered by the battery alright.


texts: Are there software to simulate timing diagrams for serial communication circuits?

texts:
For the purpose of learning(not necessarily designing), I want to simulate basic serial communication ICs such as MAX485 or MAX232. An example circuit can be as follows:

Now instead of building this circuit and using logic analyzers is there any category of simulation tools where one can see timing diagrams such as in below fashion?(I don't know what to look for or keyword):

(LTspice is free and great for analog/linear circuit simulations but it won't help with this type of circuitry since there is no SPICE model)


texts:
I have been designing second version of 4 Layer PCB. The PCB has connectors all over the PCB. In the first version, I had Copper Pour (I call it CHASSIS Ground Pour) on the bottom layer which connects SHIELD pins of SD Card Connector, Ethernet Connector, SIM Card Connector and USB Connector together. The SHIELD copper pour is on the bottom layer on the periphery of Square shaped PCB (15 cm X 15 cm). See the picture below for more details:

In the above PCB, I had four mounting holes. Three of mounting holes were connected to Signal Ground. The fourth one is connected to CHASSIS Ground copper on the periphery of the PCB (on the bottom layer of my four layer PCB).

I was planning to have a metallic sheet which will be placed on the top of my PCB. The metallic sheet will connect the SIGNAL Ground and `Chassis Ground together with the help of mounting screws (as this metallic sheet will connect all the mounting holes together). This sheet will also be touching SHIELD of some connectors.

I also had single point of connection between Chassis and signal ground on the PCB via a 0ohm resistor in the PCB.

My second version is much smaller than the first one and have many more components.

I am planning to have a SHIELD copper pour in Inner POWER Plane (because I don't have much space in the upper layers) which will run over edges of the PCB connecting SHIELD of every connector.

Is this approach is right? Is it good idea to have SHIELD copper in the Inner layers?

EDIT

I have a PCB Chassis copper polygon because the metallic sheet can't be in touch with SHIELD of every connector as connectors are spread all over the PCB (because of various reasons). They are at top and bottom of the PCB.


texts: Detecting presence of a voltage without drawing too much current

texts:
I am working on a microcontroller project for a garage door opener. Rather than supply additional magnet+reed switches or other kind of detectors for sensing whether the door is full-open or full-closed, I would prefer to make use of the existing physical limit switches.

In the open state, there is 6.5V across the terminals of the limit switches, and in the closed state, there is about 5mA flowing through. Clearly there is already some current-limiting circuitry in the machine.

In order to provide protection/isolation for my microcontroller, I have been working with an MCT9001 dual opto-isolator chip. With a 1k-ohm resistor in the emitter (input) side of the opto-isolator, I am able to regularly detect the state of the limit switches. However, the garage door opener won't operate when both switches are closed, and with that 1k-ohm resistor, apparently there is sufficient voltage drop that the opener detects that the open switch is closed.

When I increase the resistor to 220k-ohm, the opener operates correctly, but now my opto-isolator isn't operating in saturation mode and so my microcontroller isn't able to reliably determine a clear logic-level signal.

I will continue to try different resistor values, but my question is: Is there a better way to detect whether a voltage is present without drawing any more than a miniscule amount of current?

I see examples of op-amp comparators, but if I power an op-amp with my project power supply, I would have to tie the grounds of the project board and limit switches together and would lose my isolation provided by the opto-isolators. But if I power the op-amp with the switch leads themselves, I (a) will draw too much current to run the op-amp and (b) will not have any power to operate the op-amp when the limit switch is closed.

Is the better solution to find the right resistor value tolerable by the garage door opener, yet which is not so high that the op-amp source emitter is too dim?


texts: Connect a voltage regulator to another regulator

texts:
I'm trying to create a circuit that uses 3.3 and 5v.

I'm thinking about use a 9v battery, a 7805 to get 5v and a LM3940 connected to the 7805 to get 3.3v. But I can use the LD1117 connected direct to battery to get 3.3v. Some sites says that if I do this (9v to 3.3v) the LD1117 can get too hot.

Some sensors that I'm using I can connect directly to the battery.

What is best in terms of consumption?


texts:
I am trying to connect 2 motor boats with a relay to a switch. I received a drawing, but I am not understanding how the wires connect into the illuminated switch.

Here is the switch and the drawing.

Can you help me with this ?


texts: Thin film capacitor for voltage multiplier

texts:
I am designing a voltage multiplier with 5 to 10 stages. I have this circuit where I run a transformer at 450KHz and feed the output to the voltage multiplier. Is it a good idea to use thin film capacitor?
I have it lying around and also super cheap when compared to ceramic capacitors of same rating.
Name of the capacitor used(ECW-FG2J155Q1)
Lets say I am making a 10 stage voltage multiplier (Cockcroft-Walton half wave multiplier) which runs at 450KHz with 250V fed to the multiplier, I should be getting 5KV as output. Is this a good choice of capacitor? I am worried about the derating at higher frequencies.


texts: Building binary to two’s complement converter

texts:
This is a sample exam question, and no solutions were given
I don't understand the concept of 'one bit slice', and I've tried to understand the meaning of the table, I stared at it for a long time, and could not understand it.
I know that it's a binary to two's complement converter, so there is something to do with 'flip the numbers and add 1', but I can never see it one the table.
I am so stuck, please help me people.
thank you


texts: How does a single voltage reading from a microphone turn into a whole audio spectrum?

texts:
I'm having a hard time wrapping my head around this. Whenever you edit an audio file and pause it at a specific moment in time, the audio spectrum shows different levels for each frequency, all in that one moment in time. Indeed, in the real world, at any moment in time there are numerous frequencies of sound flying around. If you could "pause" your reality I would imagine there would be numerous frequencies happening, all at a different intensity. A bird chirping, the wind rushing past, people talking, etc.

Say that a microphone generates a single voltage of like +1.12 mV at a single moment in time. The audio spectrum at T=0 is composed of numerous values though.

How is a single voltage reading at a single moment in time able to correlate to so many different frequencies occurring at so many different levels happening at that single moment in time?


texts:
How do I implement a specific digital design using mealy model and then implement the same design again using Moore model ? Can anyone provide detailed steps ? Thanks.

Update:

In the digital logic class we learned what is the difference between Mealy and Moore machines theoretically and on analysis, but I don't know the difference between them in the design process.

The steps we learned for sequential circuit design:

Making a state table that shows present state, input, next state and output combinations.
Coding the binary state in the table and determining the number of flip flops.
Use the excitation table for determining the values of the flip flops needed to generate the next state from the present state.
Find the Boolean expression for the flip flop input and outputs.
Build the circuit.

From these steps I just don't know how to specify the design to be based on Mealy or Moore.


texts:
Can you explain why it is 6 * (3/9) ,Why don't we add 5kΩ resistance too,
How is this a current division,what is the formula for this.Thanks..


texts:
I want to send Step/Direction signals from Trinamic Steprocker to a stepper driver (Chinese and unfortunately with no data sheet).

The problem is that this driver requires 4 signals (Pulse+ Pulse- Direction+ Direction-) while the Trinamic Steprocker driver can just send Direction and Steps (Just two signals).

Has anyone an idea about how to interface these two drivers?

Thank you.


texts: Op-amp with constant gain for small signal(mV)

texts:
simulate this circuit – Schematic created using CircuitLab

I want to measure current using shunt resistor and I want to amplify the voltage over the shunt using an op-amp. The shunt resistor gives 60mV @ 60A. I tried LTC 1050(http://cds.linear.com/docs/en/datasheet/1050fb.pdf) but for input <20mV the gain is not constant. The op-amp has a supply of +/5V.
Vout is the signal that I want to send to ADC NI 9215, which has ±10 V measurement range and 16-bit resolution.
Do you know what features the op-amp should have for this purpose?
Which op-amp do you suggest to use?
Which circuit is the best for this application?

Thanks


texts: How to intitalize data in Program Memory

texts: Im using MPLAB IDE & C18 compiler to program Pic18f2550. I have to initialize a const string in program memory to save space in RAM how do I do it ?


texts:
Why do some analog circuits use a FET with shorted drain and source? Depending of the type of FET, it may either act as a capacitor or a diode? It each case, why not just use a cap or a diode?
Below is one example.


texts:
I am designing a buck converter that would charge a battery and planning to use an N type MOSFET on high side and FAN7085_GF085 driver to go with it.

Datasheet:

(Can't post more than 2 links, sorry).

Application note:

https://www.fairchildsemi.com/application-notes/AN/AN-9052.pdf

If the converter happens to go to discontinuous mode however, the diode stops conducting -> voltage at transistor source becomes something >0, and the internal recharge path of FAN7085 activates (as much as I understand it according to the application note, page 2).
Doesn't this short out the battery through an inductor and driver circuit?
What if I put a diode in series with an inductor (like I did in this picture)?


texts:
I'm trying the ADAU1701 (from Analog Devices) with an external SPDIF receiver (TI's DIX9211). I've noticed that if I change the sampling rate, the amount of bass at my device's output changes. The best results I get with 32KHz/16bit. I get good, full bass with this. But as I go up in sample rates, I lose more and more. At 48KHz I notice it's almost as I'm playing music with a portable stereo (this is a 2.1 system with 10" subwoofer, enough to shake things around).

I tried changing the sampling rate in SigmaStudio but it has no effect.

Measuring the master clock, with a 48Ksamples/sec input signal gives the correct 12.288MHz, LRCK is 48KHz and bitclock is 3.072MHz. This, of course, changes with the configured sample rate.


texts: Buck converter for Li-Ion 2s battery charger

texts:
I'm currently doing a project that requires the charging of a 2s Li-Ion battery.

I have an 18V 10W solar panel that I want to charge my battery using a buck converter. Im controlling the switch and duty cycle with an arduino uno which outputs a 0-5V PWM signal, I have not selected a switch yet as I am having issues trying to get my mosfet switch on and off due to the gate voltage being significantly less than my source voltage.

The way I understand it,

Before the switch the voltage is 18V, after the switch before the inductor the voltage at that node is the same as the battery voltage, 7.2< Vbat <8.2V. Therefore, for mt arduino uno to drive the switch some sort of DC offset needs to be applied to the gate so it varies from below the battery voltage (switch OFF) to above the battery voltage and turn on voltage of the switch ( switch ON).

Is my understanding correct? Does anyone have any suggestions how I can drive my switch without losing too much power?

Basically im struggling to get a PWM signal of 0V - 18V after the switch.

IN CC mode my desired outputs are 1Amp and varying voltage and in CV mode Vout = 8.4V and slowly decreasing current.

Is there some kind of IC driver that I can use?


texts:
I have a simple question and I'm new to electronics but I don't know the answer so here goes!

I have a house alarm with a loud piezo sounder. The alarm has only one output connector.

Is it possible to add more sounders in parallel with the existing one?
What electronic design constraints would I need to consider?


texts:
Yesterday, I read about TEM waves on wikipedia. Those are waves that have no electric or magnetic field vectors pointing into propagation direction of the wave.

But on any picture illustrating EM waves, they are showing TEM waves instead of the (normal?) non-TEM waves. Before reading about TEM waves, I thought that there exist only TEM waves (i.e that the characteristic about EM waves is that they are transversal).

When do non-TEM waves get created and what factors do influence the angle of oscillation of the electric and/or magnetic fields of an EM wave? How do these waves behave different in practice?

Thanks for any insight!


texts: SVPWM: space vector generation star point shifting - effects?

texts:
I keep seeing that the space vector generation (as a part of a FOC) is generated around DC Link / 2. What effects would be expected if the (in this case isolated) star point were permanently shifted?
When I search for it, I keep coming across the keyword "common mode voltage", but I still cannot conclusively understand the effects when dealing with an isolated star point.
I am aware of various literature that describes the generation of space vectors, but unfortunately I do not find any information about a permanent shift in the generation from the center (center means 50% duty cycle).
In the typical case, all FETs switch at 50% when the motor is at a standstill and thus brings the star point of the 3-phase system to DC Link / 2.
My question therefore has more of a theoretical background as to whether negative effects would be expected in the event of a permanent displacement from the center (DC Link / 2). In this case, should capacitive equalizing currents be expected (assuming an isolated star Point )? Something like that?
I am very grateful for brief feedback from an expert.


texts: What substance to use for removal of leaked NiMH electrolyte from PCB

texts:
I have experienced some problems with alarm siren (intermittently alarm goes off) in my car (Audi A3).
After removal of siren and opening its box there are visible marks of corrosion and residues from leaked NiMH battery.

I attempt to repair the siren. I will fit a new, fresh battery, but the corrosion residues is some of my concern. There is a chance it will continue to react with components/PCB.
I have desoldered the battery, but removal of the corrosion product is problematic. I have used mid-hard plastic brush and IPA as well as Electrolube LFFR (Lead-Free Flux Remover)
None of above had removed the electrolyte/corrosion product from the PCB completely. There is still some gunk left next to the components or between pins of IC where brush doesn't reach.
What is more adequate product for NiMH electrolyte spillage removal?
Or shall I desolder all affected components and clear whole area?


texts:
Previously, I've designed a PCB incorporating this ADC chip. It has a digital bus of 10 signals some of which are 40MHz.

Right now we have a four layer PCB and the ADC is connected directly to a Spartan-S6 FPGA with ~1.5" traces, running over a ground plane. The system is working well as is, despite my 0 knowledge of high-speed digital layout.

Now, however, we need to separate the ADC and FPGA into two separate PCBs. So we are going to need 10 digital signals (some 40 MHz) travelling 10". I would prefer to minimize radiation from the cable. The high-impedance ADC inputs are already shielded, but I think EMI is important to continuously consider.

Questions:

What type of connector/cable assembly to use? The world of connectors is overwhelming to me. Are IDC ribbon cables sufficient at 40MHz? Do I need 50-ohm transmission lines? Those fancy mini-coax ribbons? Can I use something industry standard that's pre-assembled, and won't cost a fortune?
Will my FPGA (and especially the ADC) even be able to drive the 10" cable? The logic is 3.3V levels. The ADC data sheet I'm pretty sure doesn't even mention drive strength. However in the timing section they specifiy 100Kohm load outputs.
Do I need to modify the design other than simply replacing the direct connection with a longer cable? How much do I need to know about transmission lines in order to solve this problem? For example, I've heard people talk about the termination of FPGA signals being important.

I know SE hates broad questions... but I'm still coming up in my EE education -- so far this is the most complicated thing I've worked on.


texts: How to safely determine which pins output a microphone signal?

texts:
I've got a Bluetooth device that has a ten-pin mini-USB output port (a Sena GP10 GoPro bluetooth audio receiver). Two of those pins output a mic-level microphone signal, but I don't know which ones. I want to figure out a way to adapt the mini-USB output port into a standard microphone TRS connector so I can plug the receiver directly into an audio recorder.

Unfortunately I don't have an oscilloscope, only a standard multimeter, so for any kind of analog audio cable the DMM gives me a reading of 0V since it averages out the positive and negative AC voltage readings.

I don't want to just blindly connect random combinations of pins into an audio recording device because I'm not sure what all the other pins do and I don't want to risk perhaps blowing the audio recorder.


texts:
I need to connect 100Mbps Ethernet PHY signals from my main board to RJ45 connector on daughter board through an on board header like shown below.

Ethernet will be used only in the board bring up phase and later we will not use it much. In main board, we are approaching this method, due to size constraint.

RJ45 connector with magnetics will be given on the daughter board.

Can you suggest me some design guidelines in this kind of approach?

Is it better to provide magnetics on the main board?


texts:
We are trying to speed control a BLDC 48V 500W hub motor using hall sensors. We are using IRF540N MOSFETs with IR2112 gate drivers and Arduino as MCU. We implemented the 3 phase inverter and in testing the following happens:

As we start the motor at 12 volts with 5 volts applied to the gates the motor starts normally and as we increase the voltage the speed increases and so the current.
The motor does not start normally as we start it from high voltage 30V for example.
With any use of PWM signal on the gate the high side mosfets burns.
When we use 48 volts 12Ah battery all the MOSFETs in the driver burns.

The below circuit is one phase from our inverter

Updated the below curve is the DC bus current at no load. At first we have a 6A spikes but it lasts for a very short time.


texts: How to predict the memory size and gate count given source code

texts:
Excuse my poor English :-)

I am in a software (for face detection) team and we co-work with the hardware team.
If we give the source code to the hardware team, they will try to implement it with hardware.

I thought it would better to first predict and consider the memory size or gate count and then give the code to hardware team.

I really don't know anything about hardware but I heard that hardware can be implemented either SoC type or standalone type.

We are first trying to make it a standalone type so we don't use SRAM to store images and we have to process the image with line memories.

Ahh... I don't even know what I'm saying.. :-(

Anyways Is there a simple and effective way to predict how much memory the source code will require?

And I also want to know about the relationship between memory size and the gate count.


texts: timer input capture for really low frequencies

texts:
How low of a frequency can a timer be used to measure an external signal in "input capture" mode?

If I need to measure something that has a frequency of say 1hz - 2hz... or even slower for that matter, at which point do I just use a standard interrupt and use the system clock to get my period measurements? Is there even a difference in the two approaches?

void myInterupt() {
  newCapture = systemClockCount;

  if (newCapture != previousCapture && captureChanged == false) {
    if (newCapture >= previousCapture) {
      period = newCapture - previousCapture;
    } else {
      period = previousCapture - newCapture;
    }
    captureChanged = true;
    previousCapture = newCapture;
  }
}


texts: What kind of FSM is it, if outputs depend on internally generated signals?

texts:
The classical definitions are that in a Moore machine the outputs depend only on the  state, while in a Mealy machine they are also allowed to depend on inputs.

But what if outputs and/or state transitions and/or register transfer opertions depend on a signal, which is generated inside the module/entity itself and  controlled by the state machine? What kind of finite state machine is it? Is it still a Moore machine?

This question puzzles me since ever I learned digital design.

Update: here a simple constructed example. let's there is a state that should be executed 5 times, and output a signal on the last.

case STATE is--inside a process
--other states
when COUNT=>

if COUNTER=4 then
STATE_NEXT<=OTHER_STATE;--state transition depends on internal signal
COUNTER_READY<='1';--external signal depends on internal signal
else
COUNTER_READY<='0';--external signal
COUNTER_NEXT<=COUNTER+1;--increment counter. this RT operation depends on internal signal
STATE_NEXT<=COUNT;
end if;
--when OTHER_STATE=>...
end case;

```


texts:
What is wrong with this circuit?

I've performed the following tests in my circuit:

When I set the controller output pin PD7 to HIGH, the source/drain voltage is 0V
(measured with oscilloscope). Signal is clean.
When I set the controller output pin PD7 to LOW, the source/drain voltage I get is a aproximate 0.5V and it's a sinewave. That means the MOSFET is not switching off (completely).

The signal from Arduino (digital OUTPUT) tested with oscilloscope, it is clean. Goes HIGH and LOW 5 V. And when I remove output wire from Arduino, MOSFET switches off and then I get clean 12V Vds.

Sensor that's wired to MOSFET is a ultrasonic sensor (VALEO Automotive). All I know about it is that the on signal wire (bidirectional, half-duplex) is 12V and 1mA.

Thank you guys! It was very helpful for me. I know that there is better solution for MOSFET then the one that I used.

I have rebuilt my assembly...I made all the wires short as possibly and voila it works!

I am not sure but I think there was a problem in Ground connection!

Also i had some confusing expirence month ago, with unloaded MOSFET and Osciloscope. That was a PWM Modulator (from PWM OCB - RMCyber..... i did some measure with osciloscope! Signal that i had with unloaded and loaded device was completly different. Signal with loaded device was OK, nice und clean PWM Signal. But PWM signal from PWM Modulator without any Load was confusing.

I thank your...i learned something new! Not everything, but step by step.


texts: Looking for external watchdog chip for Raspberry Pi 3 model B board

texts:
I'm working on a project that has chosen an RPi3 model B board as part of the system.  We previously had an external watchdog system that would cut the entire system power if the watchdog expired.  This external watchdog system has been "optimized out" now due to various changes needed for UL certification, so I'm looking to add a dedicated watchdog chip to the Rpi.  We already have a custom power supply board that plugs into the 40 pin expansion header (http://pi4j.com/pins/model-3b-rev1.html), so my plan is to do a new version of that board that includes a WDT chip.

The requirements are:

Fairly long timeout, e.g. >= 3 minutes.  We'd prefer to not have to modify the bootloader & kernel to pat the WDT while the system is powering up.  We'd like to just pat the WDT from the main userspace application.
Low cost.  Looking for a chip level solution rather than some type of external module.
The WDT can be easily patted from a GPIO line on the 40 pin RPi header
Optional - some type of indication the WDT is about to fire.  I've only used simple WDT chips before that reset the system when they expire.  I'd be quite good if we were also able to log the fact in Linux that the WDT is about to expire, then have it reset the system.
Optional - also can reset the RPi on brownout conditions.

It'd be great to hear if anyone else has made an external custom WDT for an RPi system like this and if anyone can recommend a WDT chip that can meet these requirements.

Thank you.


texts: Engineering a voltage signal with an asymmetric power spectral density

texts:
My question is as follows. I know that classically speaking, if you have some time varying signal X(t) its power spectral density S_X(f) will be symmetric around f=0 as the signal is real. This is why your spectrum analyzer only shows the positive part, the negative part is redundant.

But if one has a complex signal (such as often encountered in quantum mechanics) the PSD can be asymmetric around 0. This for example leads to the asymmetry between absorption and emission in atoms: atoms have spontaneous emission (emission in the absence of photons in the environment) but not spontaneous absorption.

What I am interested in is if there is a way to physically make such a complex signal with asymmetric PSD. I would specifically think about a voltage signal, ideally generated with some arbitrary waveform generator. Maybe this can be done by using two channels that output the signal with some phase difference? I've tried looking for some source material on this but I have not been successful.


texts: Flyback transformer one winding primary side and two winding secondary side

texts:
I have chosen a transformer from We-online type 750032051-1
and I am working on a project that input voltage 1000 vDC and output voltage 24 vDc.
I have some inquiries about this transformer:
1- how is it connected?
2- What are the inductance values of all three windings?
3- What is the coupling factor?

If i am not mistaken, the secondary side winding are connected in parallel and the values for praimary winding is 10mH and secondary winding 100µH each.
K= coupling factor is 0.994
but I am not sure


texts:
I am trying to create a comparator on the Teensy 3.2 to convert an IR receiving diode signal from analog to digital. Currently I am using an op amp, but that takes extra space and extra power, both of which should be limited for my application. The circuit is below (instead of putting output to LED, it goes to pin on microcontroller)

I'm still new to microcontrollers, and tried reading the reference manual for the microcontroller. I can see it has this function, but I'm not sure how to implement it. I thought their might be prebuilt libraries for the Arduino IDE, but had trouble finding the right thing.

The IR system is measuring the rotation of a propeller, and I would just like to have the system count how many times a blade blocks light from the emitter by looking at the falling edge of the IR receiver signal after digitizing. (In the end, too, I plan to power both off of a PWM with as low as possible duty cycle. This could affect how I do the counting in the end)

For a comparator, do I need to create the signal to compare to with a resistor divider? How do I know which teensy pins correspond to the comparator input signal?
 Could I set it digitally in some way in the MCU registers, avoiding the need for more circuit parts?

Does the output of the comparator come from a certain pin? Can I set it up to cause in interrupt instead and not use that pin, so that it executes code in the program and thats it? Is there a way to make the comparator output stay in a fixed state when the LEDs are both powered off?

Thanks for the advice!


texts: Can a DC-DC converter destroy a SLA battery or wear out very quickly?

texts:
I have 2 12V SLA batteries for recreation use in my camper. One very old (+10 years), another a bit less (unknown, maybe 5 years?).
I noticed both of them were working fine in the beginning, but now the first one is completely used up and ready to recycle (5V after 5H charge!).
But the second one is also more or less broken. For example it quickly discharge to 9V after half of the charging time on 60W only!

Now, unless the first one was its due time and because I left it too long connected parallel to the second one (can that be?), I suspect that this DC-DC converter I use for my laptop is at cause. The DC-DC converter 95W and converts from 12V to 19.9V, but it pulls amps in a very alternate way. E.g. alternating between minimum 4A and maximum 9A.

So, I'm wondering if this alternating current can quickly wear out an SLA or other negative effects?

But my more general question remains priority:
Can a (certain designed) DC-DC converter destroy or very quickly wear out an SLA?
With very quickly I mean, in months or so, compared to the years left in it.
(Since I'm going to buy a AGM battery as replacement and don't want to kill it.)

Thank you, more experienced battery users!


texts: Can this AVR MCU with 5V I2C work with this sensor with 3.3V I2C?

texts:
I'd like to interface an MPU-9150 sensor with an ATmega128 using I2C. The Atmega operates at 5V while the sensor chip operates at 3.3V.

How can I find out if the two can work together? I'm not very used to reading data sheets and don't know what to look for.


texts: Gate count and dynamic power calculation in Xilinx

texts: How do I calculate the gate count and dynamic power for a design in Xilinx? I am doing a project on Xilinx using ISE 14.7. I do not understand the gate count and dynamic power for the design.