texts: Is there a "universal" JTAG controller peripheral?

texts:
JTAG can be used to read/write data from/to FPGAs. I want to know if there is any device with an interpreter that can be used with user written STAPL files. Basically the peripheral shall wiggle the JTAG signals as required by the commands inside the user script and in this way read/write data from/to the FPGA it is connected to.
Something like this is possible with virtual JTAG with Intel devices and CoreJTAGDebug which is a wrapper around UJTAG macro found in Microsemi devices. However, I can see that the Microsemi support is not clear on this and I suspect that Intel treats STAPL and JAM files and the process I talking about as being obsolete or redundant.
Does a device that I describe exist or those folks working with FPGAs think it is just not worth the effort and has very limited application? Should I give up on the idea of trying to use STAPL files to debug FPGA designs forever and move on with life as it is?


texts: How would an alarm button work in a bathroom scale?

texts:
I am given a bathroom scale that I have to reverse engineer and beneath the bathroom scale, there is a button that sets an alarm for 24 hours from when you pressed it so that it can remind you the next day at that same time to check your weight. On the circuit board, there is the button that sets off the alarm and there is a soundbox where the alarm noise comes from. How are the seconds measured? Is it in cycles, what units would they be in? How does the scale know when 24 hours is up and how does it display that information onto the LCD screen? And when the alarm, rings, it can be turned off as soon as you step on the scale and if not the alarm will sound for 20 seconds; how does this function work?

All I know is that when you press the button, the LCD icon displays an alarm icon which indicates the alarm has been programmed to sound at the exact time every 24 hours.


texts: Impedance for Helmholtz Coil Connected to Audio Amplifier

texts:
I am trying to design a Helmholtz coil, that will have an impedance of about 2 ohms (the reason for this being that I am going to hook it up to a audio power amplifier, so to get the same wattage delivered I'm modeling it like a speaker that is 2 ohms)

If it helps thinking of using this amplifier.

First let me detail my set up:

Function Generator -> Power Amplifier -> Helmholtz Coil

I'm trying to generalize this as much as possible, so going to try and talk about it conceptually, is the best way to control the impedance in the coil is to set up an RL circuit, where I have a variable resistor so I can adjust it in turn with the impedance? And should I do the RL circuit in parallel or series?


texts: Overflow results into wrong sign-flag bit set in 8085 microprocessor .

texts:
In case of 8085 microprocessor when the MSB bit of accumulator is 1 then sign flag becomes 1 ( simply copy the result's msb) , my question is that :

When we add two positive numbers say 44H(01000100) and 43H(01000011) , the result would be 10000111 , and thus the sign flag becomes 1 , but the both numbers are positive the how sign becomes 1 ?

How microprocessor is able to handle this , please Help me out ?


texts:
I am a bit confused about QAM modulation. In wikipedia, I found this:

It conveys two analog message signals, or two digital bit streams, by changing (modulating) the amplitudes of two carrier waves, using the amplitude-shift keying (ASK) digital modulation scheme or amplitude modulation (AM) analog modulation scheme. The two carrier waves of the same frequency are out of phase with each other by 90°, a condition known as orthogonality or quadrature.

So for example, I can imagine having two carrier signals, lets say one sine wave and one cosin wave, which are modulated either by an analog baseband message signal (analog QAM), or by a digital message signal (digital QAM).
However, in another article, I found this:

The QAM transmitter first encodes bits into complex QAM symbols, which become the complex amplitudes of baseband pulses. The baseband QAM signal then modulates a digital RF subcarrier. The digital QAM signal is finally converted to an analog drive signal by a high-speed DAC.

Also, I could also find several references linking QAM to two PAM modulations. So here are my questions:

Are these two different things which happen to have the same name? My understanding is that, in the wikipedia definition, QAM has nothing to do with pulses.
What exactly is the meaning of "baseband QAM signal" in the second quote? Are PAM signals also baseband? My understanding is that we want to modulate a signal in order to transfer it to a higher (carrier's frequency) and to allow better communication (multiplexing, less interference, etc.).

EDIT
Link to paper where I took the second reference.
Link of following quote about PAM and QAM. What confuses me is that PAM is a pulsed signal, and QAM is a sinusoid. How exactly are they associated?

To simplify the basic concept, one can think of a 16-QAM signal as being the Cartesian product of two PAM4 signals.


texts: Why is this buffered rail splitter oscillating and how can I compensate it?

texts:
Inspired by the question Op amp Power supply splitter with totem pole I played with the buffered rail splitter in LTspice. I placed a current sink as load on the output to simulate the current sourcing and sinking of a connected amplifier with 100mA amplitude and 50Hz. The output is stable to 20µV, so everything is fine (Fig 1).
But when I increase the size from the bypass caps C1 and C2 at output (as one would do to bypass the supply on succeeding amplifier stages) the whole circuit starts to oscillate (Fig 2). For the screenshot I used values of 100u for C1 and C2, but even with 100n the circuit is already oscillating.

What is the reason for this oscillation with some capacitance between the new ground and the symmetrical supply rails? I would have assumed these caps would even increase the stability, as the feedback to U1 is now somewhat low pass filtered.
Can I compensate for that behaviour? How?

Fig. 1: Stable buffered rail splitter

Fig. 2: Oscillating rail splitter with bypass capacitors


texts: Current through the reverse biased junction in transistor

texts:
A transistor is a three terminal device. One terminal is called emitter, one collector and in between them is base. Now, during biasing the junction between emitter and base is made forward biased and the junction between collector and base is made reverse biased.

My question is that if one of the junction of a transistor is reverse biased, how does the transistor allow current to flow through it because the reverse biased junction (diode) doesn't allow the current to flow through it?


texts: inside the attached image,3 types of surge arresters are connected to the system in three different zones(LPZ1,LPZ2,LPZ3) , but I can't find out why F1,F2 and F3 fuses must be connected upstream of the surge arresters? are they to protect the surge arreters? how?


texts: Convert NE555 square wave output to triangular wave using op-amp(s)

texts:
I want to generate a square wave with 45% duty cycle and 465Hz on an NE555 timer and then convert that wave into a triangular wave using op amps.
I have a circuit schematic but the output generates flat signals on both ends.
I don't understand what the issue is.

Please help as it is for a group project of important nature.
Thank You.


texts: Calculating gate resistor value for enhanced active-region stability

texts:
I'm working on an electronic load design driving an n-channel MOSFET with an op-amp.

I'd like to consider adding a gate resistor (R3 in the schematic) to improve the stability.

I've searched quite a bit, but have been unable to find any hard description of just how to analyze that portion of the circuit. I understand the gate resistor forms a low-pass filter with the gate capacitance and that limits the bandwidth of the signal applied to the MOSFET, improving the phase margin and making the circuit less susceptible to oscillation.

I've also found some heuristics that the value ought to be somewhere between 10R and 1K, but I'd like to understand the design choice better.

I suspect I'm calculating a Bode plot pole for the RC filter formed by the resistor and the gate capacitance. However I'm not sure which capacitance value from the MOSFET datasheet to use (guessing Ciss = 2.4nF) and whether it's just a case of applying 1/(2πRC) to locate the pole or whether it's more complicated in this case. That works out to roughly 650kHz with a 100Ω value for R3, which makes me think maybe I'm on the right track.

Also I'd love any advice of where to reasonably locate the pole to maximize stability without negatively impacting the circuit performance. Just guessing, I would expect that bandwidth of 100kHz would be plenty, but not sure if there would be reasons to place the pole either lower or higher.


texts: Lowest Q factor than expected for a LRC paralel circuit

texts:
I tried to improve the Q factor for a tank in a LRC parallel circuit by a factor of 30. To do that I used an inductance that is 30 times smaller. To keep the same resonant frequency, I replaced the capacitor with another one that is 30 times greater. According to the math, this should work.

When I implemented the circuit, I found out that the Q factor is only 16 times greater. Not what I expected. The resonant frequency remains unchanged in the new circuit. The output voltage is also lower than what I expected.

I don't know what is happening exactly. Any help would be appreciated.
Thanks.

EDIT: I checked that the SRF of the components is much higher than the resonant frequency of the filter. So that I assume that the problem isn't related with this.


texts: Presence Detection of Factory Machines for Their Traffic Management

texts:
I'm currently planning a system for traffic management inside a factory (of its wheel kind machines).
Typically, I would use an inductive sensor which would react and indicate the vehicle presence. However, since I can't open up the ground to use these inductive sensores, I was thiking about using technologies such as RFID or NFC. In general, my idea would be sending a 5V signal whenever the presence is detected (using arduino, raspberry pi, microcontroller,etc).
However, since I never used this kind of technology, I'm kind of reluctant due to false presences born from tags that are far from the receiver but still being detected. Has anybody done something like this? Thanks


texts: System Verilog generic modules and unused ports

texts:
I have written a parametrized FIFO for reuse. Since I want to use the FIFO in multiple places I added several output signals for the fill state, like full, empty, almostFull and almostEmpty.

However sometimes not all of the output signals are used, resulting in warnings about unused signals and that the associated logic will be removed. These warnings clutter the message pane.

Question

What is the correct way to design a generic module like a FIFO, and avoid
warnings about unused ports (while using interfaces for the connection)?

Related questions:

I do not think https://stackoverflow.com/a/22272949/258418 is the way to go, since I am happy for the synthesis tool to rip it out, I simply don't want a warning for dead code removal.

While How to remove this warning in Verilog? looks related, it does not help, since I can't just remove the offending logic/wires, since they might be used by other instances of the code.


texts:
I have a problem with FFT Power Spectrum and PDS VI - I would like to see the max hold values displayed on the spectrum, but the only options in the cluster "averaging parameters" are "peak hold". Is it the same? Previously I used "Spectral Monitoring (Interactive) VI", but the peak hold values on the spectrum were not correct - I noticed that this VI uses "FFT Power Spectrum" and not "FFT Power Spectrum and PDS". Is there any difference? Can I safely replace "FFT Power Spectrum VI" with "FFT Power Spectrum and PDS VI"? Or do I have to add something to the cluster "averaging parameters"?
Thank you in advance!


texts: Please identify a resistor - it looks like the stripes are brown, black (or blue), brown, gold

texts:
The resistor in my equipment (amplifier) is burnt out, but I have found a photograph of the resistor I need to replace. It is hard to identify a replacement. The resistor is quite large and matt green. Looks like the stripes are brown, black (or blue), brown, gold. Can anyone help?

Many thanks!


texts: Difference between LW and SW in MIPS assembly

texts:
One of my homework questions was to find the 3rd element stored in an array in MIPS, here is my code

la $t0, array0 # Loads the address of variable array0 into $t0
lw $t1, 12($t0) # Loads the value of the 3rd element of variable array0 using the address stored of array0 in $t0 into $t1
li $v0, 1 # Set $v0 to 1, this tells syscall to # print the integer specified by $t1
syscall # Now print the integer

Now the next instruction is to store the value in the register $s2. My confusion at this moment is whether to use SW(store word) $s2, $t1 or LW(load word) $s2, $t1. If anyone could please give a sound explanation of the what the correct answer is and how to figure out when to use SW or LW, would be very much appreciated.


texts:
I'm hvaing trouble with my circuit, it's suppose to be a load switch to turn on a wifi module. However it's not working as intended.
The idea is to set WIFI_CTRL to high to turn on WIFI_ENABLE.

The compnents are:

Q3=TSM250N02CX TSM250N02CX

Q4=DMP1045UQ DMP1045UQ

I tried reducing the resistance of R10 to 1K and even 100 Ohm for a stronger pull-up but still WIFI_Enable is just down to 1.5V.

Can anyone pinpoint my issue, or recommend suitable SOT-23 replacements ?


texts: Mimicking an adapter with a dc power supply

texts:
Possible Duplicate:
  Choosing power supply, how to get the voltage and current ratings?

Is it possible to set up a DC source of power for a laptop so that it mimics the specs of the adapter (basically set up something with the same voltage and amperage)?

The specs I am trying to mimic are 19V and 2.42A. I'm not sure exactly how to set up something with specs near that, but I do have a model train set that can output a variable voltage amount, and using batteries might also work. Any suggestions on this would be appreciated.

I also have other adapters lying around that can be cannibalized for spare parts.

Is is harmful to laptops to use slightly too much amperage or voltage? If not I may just hook it up to a different adapter that uses 20V (I don't know the amperage, but I'd imagine it is higher).


texts:
Quoting the Wikipedia impedance bridging article . . .

  A connection is commonly said to be bridged if the load impedance is
  at least ten times the source impedance.

Why the magical numer 10?

To give this question some context: If designing a preamp stage for audio equipment, am I better off designing an amp stage that has exactly 10x the nominal source impedance of the connecting device (perhaps using an inverting op-amp configuration with appropriate resistances), or is it just as good (if not preferable) to use a non-inverting op-amp configuration to give a gigantic load impedance?


texts: Can I use 7.2v lipoly for 12v stepper motors?

texts:
I planned to buy 2 stepper motors for small toy car. What I can find from aliexpress are mostly 12v products.

I have lipo batteries already and they are 7.2v and 5400mA. Can I use this for 12v stepper motors?


texts:
Say I have low pass filter (simple circuit while the capacitor is the output.)

If I look at the frequency response at the cutoff frequency the gain is -3db. However after that the slope is -20db\decade.

I don't really undestand how much a decade is.

https://www.electronics-tutorials.ws/filter/filter_2.html

lets say I have this Lowpass filter :
meaning that the fc=159.2 Hz and if I run analise of 159Hz,1590Hz,15.9KHz  I don't get a dumping of 0.1 (-20db =0.1) ...


texts: Help with design of current load sense circuit

texts:
I'm having a bit of trouble figuring out a suitable method to sense when some LEDs in my Garage Door Opener are on. This is a continuation of this project I asked for advice on recently. However I had made assumptions which turned out to be incorrect.
Situation
A power source (perhaps the same as Vout below) runs to a 1.5Kohm resistor which runs to 6 LEDs then a transistor of some sort. The transistor is attached to ground and pin 7 on a PIC18F4520. Pin 7 on the PIC is a digital out thus I'm assuming PWM is used to dim the LEDs.
I was hoping to use the voltage across the resistor as the control signal but it seems this will be too messy/difficult.
There are four points where I can easy wire into:

Vout which labelled as 24Vdc 55mA. I measured it unloaded to be 37.5V. However with a 436ohm load the voltage was indeed 24V.
Gnd
Vrs the source side of the 1.5k current limiting resistor
Vrl the load side of the 1.5k current limiting resistor

Goal
To use the Opener as a control signal to control an external light repeating the PWM for fancy dimming. The external light is a 12V 1W LED strip. Power for the external light I was hoping to also take from the Opener's Vout using a buck converter.
Current draft

Existing parts in the Opener:
V2 = Vout and/or the LED power source (not sure if they're one and the same)
R1 is the current limiting resistor
D1-6 are the existing LEDs
Additional components for my circuit are:
R3,R4 voltage divider to power the mosfet.
M1 FQP27P06 mosfet, I've chosen another mosfet in ltspice which should be similar.
V1 12v out from the D24V3AHV buck converter.
R5 simulated load for testing in ltspice. This will be replaced with the external light.
Datasheets:

V1 - D24V3AHV Buck converter
M1 - FQP27P06 P-channel mosfet

What I'm not showing here is the power coming into the buck converter. This will come from Vout and Gnd. My primary concern here is that my output will be all whack because Vout is not a constant voltage source it seems. That and I will be modulating the load on the buck converter meaning it's voltage might go all over the shop. There doesn't seem to be any data available from Pololu on the exact behaviour.
I've simulated the PWM from the PIC with S1 and V3.
The buck converter is > 80% efficient when Vin is 24v and driving 12v @ 48mA for the LEDs. Given 24v @ 55mA is 1.32W I calculate that I can safely draw 80% of this which is 1.056W. Not much room for error however?
Summary
I haven't yet received the parts I will be using for this so I haven't tested how the regulator is affected by changes in voltage supply or loading. The info on the site hasn't been much help.
I'm wondering if there's a better way of doing this? I'm probably causing myself headaches by trying to pull a signal from these four connection points. The problem is that nearly everything is SMD and I'm not confident enough with an iron to wire into the PIC pin or anything there.
Here's a picture of the circuit board showing the PIC and some of the existing LEDs

Also, I was wondering if there would be a way to also use the SHDN pin on the buck converter to draw less power when the system is inactive. With my current draft I can't see it being possible.


texts: Optocoupler voltage drop when connected to load

texts:
simulate this circuit – Schematic created using CircuitLab

The inverter supplies max 25mA.
The optocoupler draws 18mA.
The optocoupler is supplying 1.7V to the sensor at node 1 instead of close to 5V. When I disconnect the sensor, the output voltage is 4.7V. I need at least 3.3V to power the sensor.
Any help would be appreciated.

Refer: Sensor datasheet
Optocoupler datasheet


texts: Capacitive Trimmer - Why is it full of silicone glue?

texts: I bought two of these trimmers from Digikey to tune a resonant circuit, but the screw is covered with silicone. I dug out the silicone with an xacto so I could turn the screw. Why is the silicone there? Seems counter-productive.


texts: Trimming a power supply to 0 V output in current limit

texts:
Here is another question on the originally Czech bench power supply that I recently built, but in the version¹ of it sold by various places (e.g. eBay) very cheaply.
The circuit has two potentiometers for setting output voltage and maximum output current; these are both working fine. It also has a trimmer over one of the op-amps' offset for adjusting the 0V point of the output². Right now, when the device changes to a current regime and turns off the output, I'm seeing an output of a little more than negative 0.5V, which could be potentially damaging to an attached DUT.

Things I've tried:

measuring the trimmer's resistance while in-circuit (at various settings)
removing the trimmer from the PCB and measuring its resistance that way – the trimmer itself is good
pulling either one of the offset pins to GND during the above-described condition, to see if anything will budge
pulling both offset pins to GND – again, nothing
switching out the op-amp to another TL081
switching out all op-amps for TL071s
applying a small voltage to the offset pins from a 4.2V battery
playing with the trimmer at various other output voltages – it never had any effect there, either

I then remembered that while waiting for the kit to arrive I'd read something about that trimmer in the Google Translate version of a Czech electronics forum's thread. Unfortunately I can't find that anymore, but am now suspecting that something might be wrong with the circuit design itself.
What could have been the idea behind putting that trimmer there and what might be the reason(s) for it not doing anything, or at least, not doing anything apparent to me at this point?

¹ These PSUs are said to be adaptations of https://www.electronics-lab.com/project/0-30v-laboratory-power-supply/, which is an adaptation of https://www.electronics-lab.com/project/0-30-vdc-stabilized-power-supply-with-current-control-0-002-3-a/, which is an adaptation of http://paja-trb.cz/konstrukce/zdroj.html, which is an adaptation of the original work at http://paja-trb.cz/konstrukce/zdroj/zdroj_G400.pdf by (brothers?) Jindrich and Tomas Tolg.
² According to https://www.qsl.net/z33t/dc_0-30v_0-3A_eng.html ("The trimmer RV1 and the resistor R10 are used for the adjustment of the output voltages limits so that it can be reduced down to 0 V, despite any value tolerances of the other components in the circuit").


texts: Is this the correct w recognize Opcodes for a DIY 8bit Processor

texts:
simulate this circuit – Schematic created using CircuitLab
i am starting with designing a 8bit computer and probably turn it into reality , so lets say i start with a 8bit 32kb memory and i want to store some bytes into it in a way i hypothetically know , lets say i have a byte 00010011 where 0001 is the first opcode and 0011 is the address so what should be the correct way to build the hardware that can recognize the 4bits 0001 , what i think is that inverting the 0 , 0 , 0 into 1 and passing all 4 into a 4 input and gate could be the rule of thumb for all 15 opcodes i would possibly need to be there in my 8 bit processor . So is this the correct way to do it


texts: Do I need filtering caps for a USB power supply?

texts:
I'm pulling 5V from USB for testing an IC. Should I put a capacitor in there to filter the power supply, or will it already be steady coming from the laptop?

I don't have access to an oscilloscope, so I can't check how noisy the USB voltage is.


texts: Micro Controllers to control Solenoid valves upon receiving signal from PIR Motion Sensor

texts:
I am using a PIR Sensor of Sparkfun(Model 8630) to detect human's presence in washroom.
If there is no human presence in an interval of 30 minutes, the Solenoid Valve connected to pipe line in the area has to be closed.
How can I make it possible with the help of this sensor? Will a microcontroller unit is needed? I have to use this same sytem in 120 rooms of a building.
Please Advice


texts:
Is there any way to draw routing on a PCB in the software PADS Layout without any components, like the CAD images below? If PADS Layout doesn't work, does Eagle have this function?

Also, can I resize the radius of the circle after drawing it?

Thanks a lot!!!


texts:
I read about the 3-state buffer. I do not precisely understand the working mechanism. It allows essentially to obtain a third state, that corresponding to the disconnection of the output from the circuit (eg. a bus).

This disconnection of what exactly it consists?
In what sense the corresponding Z high impedance state differs from
the standard state 0 of ordinary output?
Can we get a complete absence of current, when the buffer is active?
If this is the case, how can that result be reached?


texts: What determines the voltage of an electric motor?

texts: What determines the operating voltage of an electric motor? And could an AC motor be run at a lower voltage (i.e. 80v) and how? I'm not sure if its the windings turns or thickness of the wires which determine this but I'm guessing it's something related to this. I'm trying to understand if there is a possibility to build an ac motor to be run on lower voltages with a dc supply into a controller (VFD).


texts: Address bus, databus: how much storage direct accessible

texts:
I have a CPU with a 32 bits data bus and a 21 bits address bus. I would like to know how much storage I can connect to this CPU directly.

Does this depend on the address bus width, because I can just address 21 bits of these 32 bits data or how does this work?


texts: Using a 12V battery while simultaneously charging via solar panel

texts:
I have a couple of 12v batteries that I'd like to use to power a cooling apparatus while camping for several days.

I also have a 15W solar panel I'd like to use to top-off the battery.

Can I use the battery while it is charging? Or would I have to disconnect the solar panel prior to using the battery?

Alternatively, I could charge 1 battery while using the other, and simply swap them out - is this preferable?


texts: How do I get the FSM table from the given diagram?

texts: Given one is question and another solution. I cant come to this solution. can anyone help here


texts:
I've successfully built a VCO using an LM13700 OTA. The circuit generates square and triangle wave. I wonder if I can add a couple of diodes and a potentiometer to be able to skew between triangle-ramp/saw and change the duty cycle of the square wave? Is it that simple?

The second schematics gives you an idea of what I meant. It's a similar circuit realised with op amps.

Any idea would be very much appreciated!


texts: Single chip solution for power suply, 5v and 3.3v output

texts: Im developing a sensor that needs 3.3 and 5 volts, my actual design use a simple combination of a lm7805 and a lm7833, given the fact that space efficiency is important in this project, I  wonder, is there a single chip solution to have that dual output? Thanks for any help!


texts: Understanding the Design of Common ULN2803a Motor Driverboards (use of the capacitor in particular)

texts:
I'm studying a popular motor driver board based on the ULN2803a Darlington Array chip (top and bottom pictured below).

A capacitor is between the common diode/flyback trace and GND.

Does the capacitor collect the flyback energy and return it into the supply current? I presume this happens whenever the differential between the cap's stored voltage and the supply voltage reaches certain level?


texts: Will my car's AM/FM antenna boost the signal of a tablet/carputer GPS?

texts:
I'm installing an Android tablet as a carputer in my '97 Hunk-o'-Junk Crapwagon, and saw a reddit post detailing a carputer install where OP linked his Jaguar's antenna to a USB GPS adapter. OP also mentioned that adapters for such connections are available for cheap on eBay, but doesn't seem to be responding to further questioning.

I understand that antennas are a complicated subject that I would do well to bone up on, but this would at best amount to a nice touch to an otherwise low-priority kind of project. Would finding a way to connect my car's AM/FM radio antenna to the GPS module inside a tablet appreciably improve the reception?

Obviously, it would be far from optimal, but would it be anywhere near worth the trouble? Even if it boosted the signal, would it translate into a noticeable benefit for the speed and accuracy of location services? I'm betting the tablet would work okay unassisted anyway, but the idea of utilizing a pre-existing connection appeals to the scavenger in me.


texts:
I need a cable for something I'm working on, but I don't want to just cut off the connector for the existing cable, can you help be identify the type of connector this is so I can buy a new connector make a new cable and I don't have to ruin this cable?

Oh, and if it helps, this is a connector from inside a tablet for a wacom digitizer.

edit: oops, forgot to include measurements, it's somewhere between 1/2 an inch and 9/16 of an inch wide. and 1/16th of an inch thick


texts:
I have the following snippet of VHDL code which is misbehaving and I don't know why:

process (clock)

variable counter : std_logic_vector (15 downto 0) :=  x"0000";
variable op : std_logic_vector (7 downto 0);

begin

if (clock = '1') then

    op := cw (15 downto 8);

    -- This if statement is misbehaving
    if (op = x"20") then
        counter  := counter + cw (7 downto 0);
    end if;

    counter := counter + 2;

    ia <= counter;

    end if;

end process;

As the simulation shows, the code increments in counts of 2, but the cycle after the if statement, weird things happen

Sorry, the top waveform is the clock, then "cw" and "ia" at the bottom

EDIT: The code is supposed to count up by 2 by default. If the upper byte of "cw" is 0x20, then it is incremented by 2 and another number


texts: What is the use of an AC Power Entry Module?

texts:
I found the following AC line outlet in an old box used in outdoors:

And could manage to find its datasheet.

But in what kind of circumstances or conditions is this filer used? I cannot see any transient suppressor in it.


texts:
I'm trying to get the internal RTCC working but it doesn't seem to work.

What I'm using-

MikroC pro for PIC
using internal 8mhz clock(INTOSCPLL)
Using INTRC as a clock source for RTCC

and using the following code:

 void main() {

 char txt[7];

 //Setup RTC
 T1CON.T1OSCEN = 1;
 delay_ms(50);
 RTCCFG.RTCWREN = 1;
 PADCFG1.RTSECSEL1 = 1;
 PADCFG1.RTSECSEL0 = 0;
 RTCCFG.RTCEN = 1;
 RTCCFG.RTCPTR1 = 0;
 RTCCFG.RTCPTR0 = 0;

 //Set analog ports as Digital
 ANCON0 = 0x1F;
 ANCON1 = 0x1F;

 I2C1_Init(400000);
 Oled_Init();
 Oled_FillScreen(0x00);

 while(1){
    IntToStr(RTCVALH, txt);
    Oled_Text(txt,0,2);
    IntToStr(RTCVALL, txt);
    Oled_Text(txt,0,4);
    delay_mS(1000);
 }
}

The RTCVALH and RTCVALL should display minutes and seconds. But their values don't change at all. They show constant values of 56 and 50.

What steps am I missing?


texts:
I have a question regarding the frequency response of a boost converter.  I am curious to know what causes the "blip" at around 8kHz that causes the response to go up and then back down.  At first, I thought that perhaps it may be a ESR zero, but thinking more closely, a single zero would not cause the response to rise like that.  Furthermore, the response shows another pole afterwards, and I can't quite see where its coming from either.  Anybody experience this or seen the cause of this before?

LLC resonant converter


texts:
I recently replaced 5 capacitors in my Syncmaster 225BW after it was having severe issues maintaining steady output. I referred to this video for the instruction and replaced the capacitors as demonstrated: 3 x 330uF & 2 x 820uF. Usually includes but missing from my kit was one of the smaller 47uF capacitors.
After said replacement, the monitor performs well with a steady output, though still has a serious issue powering back on after using the power button the front bezel. There is also a faint amount of ghosting present, most noticeably when moving the cursor over a white background. Another hint is that the display emits a not insignificant amount of buzzing when the brightness is turned down.
Difficulty powering on is often known to be a capacitor issue though I am not sure if the ghosting is solved the same way. Is it worth trying the same repair with the full set including the smallest 47uF capacitor and possibly also the largest capacitor not included in any kits I've seen? Or is there another front I ought pursue in the restoration effort of this monitor?


texts:
I see many LEDs for sale using this size:

What form factor is this? I want to buy empty enclosures to place some LEDs that I purchased into. I assume that their are enclosures available because so many LEDs are this standard size/shape.


texts:
I have been trying to design a functional board which combines the hardware of the Elecrow Arduino Uno CAN bus shield with a microcontroller board, which functions like an Arduino except with different hardware. This design can be programmed, with the appropriate software drivers for the Arduino IDE, but it skips over all of the CAN stuff.

This picture shows the connections between the PIC32 and the MCP2515 CAN controller.

Ignore everything in the image except the connections that exist between the CAN controller and the PIC32. I have probed some of the serial lines between the two chips and found that there is no clock signal. As such, there is no way the SPI module can be working, except how does the Arduino code run?

void setup()
{
  Serial.begin(115200);
  while (CAN_OK != CAN.begin(CAN_500KBPS))
  {
    Serial.println("CAN BUS Shield init fail");
    Serial.println("Init CAN BUS Shield again");
    delay(100);
  }

  Serial.println("CAN BUS Shield init ok!");
}

Above is just a snippet of the code used to initialize the CAN bus in the Arduino IDE. When the CS bit is set to anything other than 10, the program will just loop through the while loop, wherein it complains that the CAN bus has failed to initialize. In the alternative case, it will simply skip over all the CAN commands as if they weren't in the code and everything else in the program runs fine.

So as mentioned, I found there was no serial communication between this chip and the controller. In fact, the program switches on globes connected to FET switch circuits when it senses ground at the analog ports. When this occurs, there is a sudden random surge on the clock line, but how can this be possible unless the chip is broken? I said to somebody before that if the SPI module was damaged, wouldn't the entire chip not work? Please note that the text "CAN bus init OK!" does not appear in the serial monitor, when the PCB is connected via USB.

My next line of reasoning was that perhaps I needed to change the baud rate to match that of the SPI module of the PIC32. It doesn't matter what I change it to, the CAN bus does not initialize. Another engineer looked at the design and noticed that by connecting the MCP2515 to 5 V would cause the crossover voltage on the ports to have a VIH too high for the chip to function. This pin was disconnected and connected to 3.3 V which should fix part of the problems I was having, but this serial communications problem remains unsolved.

If anyone has any useful hints or experience in this area and could shed some light on it, I'd appreciate it greatly.


texts: Help Identifying components in Teensy 4 schematic

texts: I'm following the official schematic of Teensy 4.0 from pjrc.com to build a custom board. Can somebody please help me identify this unlabeled component encircled (Red) and this connection label encircled (blue). Here is the complete schematic of Teensy 4.0. Thanks.


texts: how to step down the voltage from 100V(after a FullWaverectifier) to 1V without affected by noise

texts:
How to step down the voltage from 100V(after a Full Wave rectifier) to 1V without affected by the noise?

The task

I have 70Vrms sine wave, I rectified it with full wave rectifier. So  the output is  100Vp.I will divide it down to 1V using voltage divider (0-100V to 0-1V).
How could I add a 1.4V DC bias to the output of the voltage divided ?

Briefly:
$$ 70V_\text{rms} \Longrightarrow  0-100V_\text{p} \Longrightarrow 0-1V \Longrightarrow 1.4-2.4V$$

I have a 5V DC I could used it in the biasing

The solution I used

I try with voltage divider and I had a lot of noise since 10V will give my 0.1 Vout.

Here is my project

When the voltage is 56Vrms, I get the following results ( the green is the signal at PWM pin1 and the yellow is at R6 -the AM demodulator- )

The voltage at pin 1 of the PWM IC (UC3526AN) have to be 1.4VDC bias with 1Vpp  when the input voltage is 100Vpp but it is not.
The following is the real measurements at pin 1.

The results and the problems

At about 20Vrms input

At about 30Vrms input

At about 68Vrms input

At about 100Vrms input


texts: The detailed working steps of the DRAM 3T1C cell?

texts:
This question is related to this one. But the focus is a little different so I put it here.

I tried to understand the detailed working steps of below circuit. It is an old 3T1C DRAM cell circuit. This picture is quoted from the book Memory Systems by Bruce Jacob.

I think the input capacitance of T2 is just a representation of the T2's characteristic, which is not a real capacitor. I know that conceptually capacitance is defined as the ratio of q/V.

My first 2 questions are:

Does this input capacitance of T2 mean the ratio between the charges q and voltage V required to open T2's gate?
If the charges remain on T2, will T2's gate stay open?

Below is my understanding of the circuit steps:

I guess:

write rowline is active-high
read rowline is active-high
write bitline is active-high
read bitline is active-low

Steps to Write and Read "1" to and from the cell

Steps:

write rowline goes to high to signal the write operation. T1 is opened.
write bitline goes to high because we are writing 1.
write bitline reaches T2 through T1. T2 is charged and opened.
write rowline goes to to low to finish the writing. T2 is charged and opened.
read rowline goes to high to signal the read operation. T3 is opened.
read bitline reaches T2 through T3.
Because T2 is opened in 3, 4, so read bitline further reaches ground through T2. So read bitline reads 0 (ground).
Because read bitline is active-low, so the 0 voltage in 7 is interpreted as a logical 1.

Steps to Write and Read "0" to and from the cell

Steps:

write rowline goes to high to signal the write operation. T1 is opened.
write bitline goes to low because we are writing 0.
write bitline reaches T2 through T1. T2 is not charged or opened.
write rowline goes to to low to finish the writing. T2 is not charged or opened
read rowline goes to high to signal the read operation. T3 is opened.
read bitline reaches T2 through T3.
Because T2 is not opened in 3, 4, so read bitline reads the voltage of read rowline through T3, which is high.
Because read bitline is active-low, so the high voltage in 7 is interpreted as a logical 0.

Am I correct?


texts: Weird oscilloscope readings with a digital signal (ws2812)

texts:
Pretty new to oscilloscopes.  I'm trying to learn stm32, so one of the projects I'm working on is getting ws2812 LEDS working on stm32.  It does work for most strips, however, there are few strips that give me really weird signals on the oscilloscope.

In this first screenshot, I'm probing one of the LED strips that doesn't work.  Notice that even though the signal should be 5V, the signal starts and then immediately drops to below 3V.  I would like to note that this LED strip is known working, and works with an arduino using the Adafruit NeoPixel library.

And here's what it looks like hooked up to one of the LED strips that works:

Here's a basic schematic of the setup I'm using (I've got two 100nF caps for the TXS0101 and a 10uF capacitor for the 5V supply that aren't shown there).


texts: What is the difference between a multimeter with RMS and one with True RMS?

texts:
I am looking for multimeters. I am only a beginner in electronics, but I want to buy one that will be good enough for me for a while. I found a multimeter that measures True RMS, and another one that knows the same but without TRMS.
(both made by HoldPeak, if anyone cares.)

The smaller shape of the latter would be handier and it costs 2/3rd of the TRMS's price, so I ask Your advice, Experienced Electronics Experts:

In what cases, and how much does True RMS matter? What is the difference between RMS and True RMS?


texts: Identify the pins of the circuitry that resides within a laptop battery

texts:
My ASUS laptop battery stopped working all of a sudden, when it had no reason to (new). Windows says "Plugged in, charging" , but the battery always stuck at 0%.

Before getting a replacement battery, I decided to investigate a little bit and opened up the battery case(A41-X550A external, detachable). It's just four 18650 cells connected in series with a PCB consisting of a few ICs, an NTC thermistor and a connector that goes to the laptop. I checked the voltage of each cell and found them to be around 3.7 Volt, which makes sense as the battery is rated for 15 V, 2950 mAh.

However, despite the battery providing 15 Volts at the end terminals of the 4 cells in series, I am getting no output (0 Volts) from the positive out of the connector which is a part of the PCB. There are 5 other pins on the connector (ID, D, C, SYS, NC). Apart from the Not Connected pin, I am not sure what the others mean or stand for. I am convinced that I will need to operate on one of these pins to "switch on" the connection between the battery out and the 15 V from the series cells.

Pictures have been attached and it would be extremely helpful if someone could identify the pins and also maybe a possible fix to the whole conundrum.

P.S- I tried shorting the 15 Volts and the battery out and connected it to the laptop. Nothing new. Plugged in, charging and 0%.
I also got a battery of the same model from a friend who had the same problem. Opened it up and again, all the cells are healthy with no output at the battery out pin.


texts:
I'm hung up on how to smooth analog sensor data in a specific way. Math/code is not my expertise so thanks in advance.

My sketch needs to listen an AnalogPin and smooth/remove any outliers as the values change, though smoothly settle on the final AnalogPin value.

Ex. if the sensor is a Mic in an empty room and over 30-60 seconds the room fills with people, I'd need a MicValue that slowly grows to the new volume but omits any initial foot steps or major peaks.

Ex. if the AnalogRead pin is a potentiometer, rapidly rotating the knob for 5 seconds wouldn't have much effect, but where the knob ends up the value would slowly settle upon.

Any help to define what I am looking for, or help with code would be greatly appreciated. Thanks!


texts: Externally Triggering a camera Using a TTL Signal

texts:
I am not an electrical/electronic engineer, so please bear with me.

I have a monochromatic camera (www.qimaging.com/resources/pdfs/QICAM-12bitManual.pdf) which can be triggered (i.e. capture image) by a 5v TTL signal provided by an external triggering system (a function generator). Also, the camera comes with an electronic triggering board related to this application (www.qimaging.com/resources/pdfs/ExtTrigApNotes.pdf) (www.youtube.com/watch?v=LuC_-cUO97c). So, the function generator output is not directly connected to the camera. The BNC cable from the function generator would be first connected to the triggering board; then the triggering signal will reach the camera through a circular DIN port. One thing this triggering board does is it allows you to monitor the exposure time and readout time of the camera (so I think this is one way to see if the camera is triggered or not, right?).

So, basically I want to feed the camera a 5v TTL square signal (DC) and make the camera capture an image (i.e. trigger) on edge high mode. I also, have an external light source, supplying the required light for the image, which also need to be synced with the triggering TTL signal on edge high mode (www.hsps.com/2006/pages/nanodren.htm).

I have come across a few issues for which I need help from you:

1) I am using a function generator with an in-built TTL output (BNC connection). So, when I monitor the function generator output, the voltage amplitude is not 5v, but around 4.2v. That persists even if I set the function generator's impedance to High Z. I tried two different function generators and I get the same 4.2-4.4v. What's the reason behind this? How can I get an exact 5v TTL signal?

2) You may ask, your camera surely works (will trigger) even with a 4.3v signal. You are right. But it gets problematic when I also connect the external light source (required for higher quality image) to the function generator to be triggered at the same time as the camera. So, when the BNC cables from the function generator output is connected to the oscilloscope, my voltage is around 4.3v, but the moment I connect another BNC cable to the same output in the function generator and plug its other side to the external light source, the voltage amplitude drops to around 3.6v (probably due to internal impedance of the external light source), which may not enough to trigger the camera.

So, although the function generator might be giving out a 5v signal when there is nothing attached to it, but this surely drops to a value of 3.6v with all the BNC cables connected to it. My question is that how I can make sure a 5v signal (DC square) will reach both my camera and my external light source.

Please let me know if you have other suggestions for my case.
Hope my post won't get deleted due to not following the forum guidelines.
Thanks in advance.

Note: internal impedance of the function generator is 50 ohm.


texts: How can i convert 220V to 9V without using transformer?

texts: I am making a sound amplifier using LM386 and 8 ohm speaker. Can anyone tell me which IC is most suitable and how to convert 220V to 9V to operate the circuit without transormer?


texts: Obtaining frequency of 550 Hz from Simple Triangle and Square Waveform Generator Circuit

texts:
First time asking a question so sorry if I miss some things. I'll try to be thorough and straightforward.
I'm trying to design a square wave from a triangle wave-square wave generator circuit. <img src="https://i.stack.imgur.com/u1TIt.png" alt="Simple Triangle
& Square Waveform Generator" />
The output wave should be running at 550 Hz with a 2 Vpk-pk, and an offset of 1 V, which is why I added a diode network at the output of the second op-amp.
The thing is originally I was having trouble getting the right frequency of the signal. I solved for R1 using the following relationships, setting C1 to 0.1uF:
$$
t = R1C1 = \frac{1}{f}
$$
Which gave me:
$$
R1 = 18.18 k\Omega
$$
Also, finding the time using frequency gives me:
$$
\tau = 1.82ms
$$
My problem is I'm not too sure how R2 and R3 affect the frequency. Basically, I 've been switching out resistor values and found changing R2 affects the frequency the most. 3.42 k, gives me the right tau, but I'm not sure why though.
I know that the second op amp acts as a comparator, right? So I'm guessing the voltage between R3 and R2 is the threshold. But I'm still a little lost on how that relates to the frequency of the signal.


texts:
Previously today, I tried to make an extremely simple AM receiver without a tuner. It didn't really work (I'm still trying to work on it), but I also tried to make an AM receiver that is tuned to one single frequency (approximately 960 kHz).

I made this circuit on a breadboard (except the 100 ohm resistor), but it's not working. I can't hear anything at all. Can anyone give me any guidance?

To explain my circuit a little more, I just used 2 (and also tried 3) BC547 NPN transistors to amplify the signal, and used a diode to filter out the negative voltage. And my positive terminal and ground are just the positive and negative sides of a 9V battery. Also, my piezo buzzer is powered by DC voltage. Thanks!


texts: Is it safe for a screw at the terminal block to have multiple wires with fork connector end connected to it?

texts:
I have a DC-DC converter (24v to 12v) that has terminal block at its input and output terminal. To understand it better, I've attached the drawing of the converter found in its datasheet.

Problem: This converter is used at work. And the existing configuration connected by others has multiple wires with fork connector end connected to each of the screw at output terminal.

Question is: Is it safe to be stuffing multiple wires with fork connector end into one screw terminal? And what is the understanding behind?

If further clarification is needed, feel free to leave a comment. Thanks for your interest and help.


texts:
I am having a IR Sensor Module which i had got in a Robotics kit.
But it has a connector similar to RJ-45,

I wanted to use it with my arduino and hence wanted to desolder that jack and use jumper cables instead, but i m not sure what terminals 6 terminals of that module are.....

i observed that there are two IC - LM358(comparator) and IC - NE555 (timer).

can you pls help me undersanting these 6 teminals inside that square are... one might be vcc and other gnd....what about others???


texts: Making LM317 output voltage adjustable down to 0 V

texts:
I want to design a variable voltage regulator that will get from it`s maximum output (lets say 10V) down to 0V (or very close) considering the input as regulated 12V (from a PC power supply).

All the designs that I found use the 317 IC and can not go under 1.25V and I am pretty sure that there must be a way to do so.

I could not find any tutorials that explain in an easy way the way that the 317 behaves (beside the classical configuration) so any additional explanation is welcomed.


texts: What are the "embedded" and "non-embedded" design flows?

texts:
I'm reading the Spartan 6 user guide on the Memory Controller Block (MCB). The following quote discusses two design flows:

  There are two supported design flows for the MCB:

  1) Non-embedded design flow

  Conventional FPGA design with the Xilinx® ISE® tool flow
  MIG tool is used within the CORE Generator™ tool for MCB designs

  2) Embedded design flow

  Processor-based FPGA system design with EDK tool flow
  IP Configurator in Xilinx Platform Studio (XPS) is used within the EDK  environment for MCB designs

I'm not quite sure I understand the difference between the two design flows (despite the above "explanation"). What are the non-embedded and embedded design flows?


texts:
Is it a good practice to put polygon pours on the top layer underneath a BGA?

I've occasionally got several GND or VCC pins in a row/column, and I'd like to pour around them all.  I've got the same vias I would otherwise, this is just in my mind lowering the inductance between the pins and the vias.

The soldermask would then define the pad shapes.  Is that safe?

Is there any SI reason not to do this?  I can't think of a negative... it may even add a little more buried capacitance.

Is there any reason I shouldn't go nuts with pouring over everything?  (Being careful not to leave islands or little antenna structures)

I don't see this in the few reference designs I've checked...  so I'm curious why not...

EDIT:

Would this somehow prevent the ground plane from being as effective?  (If there's a large VCC pour between it and the BGA)


texts: Is it really the Power required for comparing input and output?

texts:
Hi I want to drive a 5W (5V*1A) output... Can it be carried by a 10W input (15V*0.670A) ? Is it just the power needed? Or should I need a larger current than 0.670A ?

Is this applicable for LDO Regulators or/and Switching Regulator?


texts:
I'm trying to translate a circuit I made from breadboard to PCB and need some help finding out what components I should be looking for.

Basically, so far I have a very simple circuit running 12V AC, at about 10-20A using a relay.

I'm controlling this relay with an arduino, so if I give 0v the circuit flows towards circuit A, and if I give 5v, the relay switches the flow to circuit B.

My issue is that the relay is too big for my application, I need something smaller, that I can fit in to a smaller chip.

From my research FET's is what I should be using, but are there other easier components I can use? With FET's, I will need to use an optocoupler to drive them from the arduino correct? Are there simpler ways?


texts: Designing equipment enclosure and using anti-tamper earthing bolts

texts:
A bolt head is often seen on the outside of the enclosure of many devices (e.g. power supplies), marked as earth bonds. The head of the bolts I am referring to does not have the usual drive geometry, so that it is difficult or impossible for the user to loosen them.

This makes sense for safety reasons (if the bolt is removed, earthing of the enclosure may fail and safety would be compromised).

Could someone please provide some rationale as to when/why protruding plugs/bolts, as opposed to other solutions, would make sense in earthing an enclosure?


texts:
I'm making a  Metal distortion pedal
ill be using  6 potentiometers
POT1    Distortion          250K
POT2    low freq control    100K
POT3    high freq control   100K
POT4    mid                 100K
POT5    Gain                    10K
POT6    volume                  50k

But which type of potentiometer is suitable for each ??
Logarithmic?
linear?

Distortion-Distortion effects create "warm", "dirty" and "fuzzy" sounds by compressing the peaks of an electric musical instrument's sound wave and adding overtones

Low, Mid, and High refer to the frequencies that effect the tone of the amp. Low being low frequency, Mid being middle frequencies, and High being High frequencies.

If you want your guitar tone to be bassy you'll turn up the Low, If you want it crisp or tinny you turn up the high. Mid frequencies generally are associated with clarity and definition or body of the tone. for example if you turned the Low and high up, and left the mid down, you'd get a boxy sound.

But i do not know which pot will achieve the required control over them LOG ? Linear? :(

Here is the circuit diagram


texts:
I looked at this thread already -

"How to choose an ARM Cortex M3 microcontroller"

However, my question is a bit a different. I want to focus on more of a learner/beginner's perspective. As the other thread also mentioned, the development kit makes a huge difference, and more so for beginners I believe.

Although, the choice of development kit is an opinion, I would like to know what kit has the most support? (In terms of volume). I tried to look it up, but could not find anything conclusive. I suspect its the Keil kit given it was bought up by ARM, but I am not sure.

Also, is there any data on free vs paid kits and the amount of support they provide?

The second part of my question is, what dev. boards are good for beginners? Since, the main aspect is learning to program an M3, not performance - i suspect, there are cheaper options available for playing around. I found a couple, namely in the ST32 category and another board called Matchbox, however I could not find anything conclusive. I was looking for evidences like this particular chip is used in universities to teach a course etc. (I looked up a few university course pages as well).

Any help is much appreciated!


texts: Misunderstanding of calculating gain of amplifier

texts:
I’ve been reading in my textbook that the gain is
Gain= Vout/Vin= 1+ Rf/Rin
However, what if there isn’t a resistor like this amplifier?
Would it be 1V/V or 2V/V? Or am I totally misunderstanding this?
Any help to clarify would be greatly appreciated


texts: If I take a USB cable connect it with my cellphone from 1 half and in the other end I connect VCC and GND to VCC and GND pins of the arduino and the D+ and D- pins to digital pins and use a differential to single ended signal converter (or make one using an opamp) can I actually read data sent from my cellphone to Arduino?


texts:
I am trying to build a portable light source - running (exclusively) on a 12v electrical bike battery. Have it operate approx 1 hour on a charge and produce the maximum possible lumens.

What would be the best approach Led and driver wise? (Strip/die?) A bit lost trying to calculate what components will fit best.


texts: Using capacitor to protect circuit from split second power disconnects

texts: I have a circuit powered by a 9V battery. The circuit will be subjected to significant vibrations. I want the circuit to not power off if the battery is disconnected for a second. Would a capacitor in parallel with the 9V battery do this? How do I know what capacitance I should use? Also, would the capacitor draw too large a current when the circuit is initially powered on?


texts: Can someone help me identify this connector? I need to source a male to plug into it.


texts:
I am checking some Spice models of transmission lines.

I have a Belden 1583A Ethernet Cable, with the following parameters \$R=93.8 \ \Omega\text{/km}\$ and \$Z_0=100 \Omega\$, hence \$C=47.652 \ \text{pF/km}\$ and \$L=0.47652 \ \text{uH/km}\$, for \$D=1 \ \text{km}\$ (check).

I took an approximation with \$n=8\$ discrete modules of RLC circuits each with one series R + one series L + one parallel C with the above given parameters, divided by \$n\$, as depicted.

I considered a sinusoidal source with \$v=1\ \text{Vp}\$, (peak to zero amplitude) \$f=100\ \text{MHz}\$.

I took an Inverse Hybrid G Parameters 2-port Matrix, with the following code in Matlab.

%% Belden 1583A Cat5e
% V: 1V,100MHz
clear all; clc;

c=299792458;
VF=0.7; Z0=100;
C=1/c/VF/Z0; L=Z0/c/VF; R=93.8;

% Distributed Impedances
v1=1; f=1e8; k=8;
j=sqrt(-1);
ZC=1/(j*2*pi*f*C/k); ZL=j*2*pi*f*L/k; ZR=R/k;
% B: ABCD' Form / Two Port Network Matrix
% V1I1 -> V2I2
B=([1 -ZL-ZR;0 1]*[1 0;-1/ZC 1])^k;
% G=inv(H): Inverse Hybrid Form
% G: V1I2 -> I1V2
G=1/B(2,2)*[-B(2,1) -1; det(B) -B(1,2)];
% Open Loop
i2=0;
x1=[v1;i2];
x2=G*x1;
i1=abs(x2(1)); v2=abs(x2(2))

This brings an output of \$v_2=0.924\ \text{Vp}\$, phasor magnitude.

However the same circuit simulated in two different programs, with zero initial conditions, and for any convergence settings, brings \$v_2=0.873\ \text{Vp}\$, sinusoidal steady state. Too much difference for an accuracy setting.

Why could I be having this difference?


texts:
Time transfer in the late 19th c was best achieved by telegraph, a major improvement in the determination of longitude for geodetic surveying. A question was posed, to acquire a high accuracy time, by the use of telegraph, how much signal delay would be attributed to the signal propogation over telegraph lines?

How much delay would a telegraph signal have in a 900 mile telegraph time transfer?


texts:
By experience I have got to know that the cable normally used to drive Led strips (22AWG) is not good anymore if it is longer that 10 meters.

I realized this while working with 5 pieces of 2 meters of WS2812b where all of them are several meters apart from the Arduino board that I use to control them. In that case, I was sending the same program to all of them, and what I did was to connect all of them to the same pin, and it didnt work at all. The sum of the lenght of all 10 cables was much longer than 10 meters, and the signal got lost.

While searching for a solution, I discovered a post by Teknynja (http://www.teknynja.com/2014/02/driving-ws2812neopixels-rgb-leds-over.html?m=1) where it is explained how to use SN75176 to be able to drive WS2812b on cables much longer than 10 meters. I did the experiment myself, and even though he uses CAT 5 cable, I was able to succesfully send signal over 50 meters of 22AWG cable.

After that, I used SN75176 not to use longer cables, but to split the signal from the output pin into 5, and then I could connect 22AWG cable to drive each piece of led strip apart from the board some 10 meters each.  (images of the board at the bottom of the post)

so far, so good.

Now I was trying to drive 4 pieces of 2 meters of WS2812b that are some 8 meters away from the arduino board, and again they are all displaying the same program out of a single arduino pin. So I connected a 8 meters long 22AWG cable to the arduino, which is inside of the restraints previously mentioned, and at the end of this cable I connected one of my "splitter board", to send the signal to the 4 Led strips. It didnt work.

I have the feeling that the SN75176 do the job only if it is connected close from the arduino board, but if there is already a lenght of cable between the pin and the driver (SN75176) the signal is already weak enough or noisy enough for the SN75176 to manipulate it properly.

I of course did a lot of try outs in different circumstances, different cables, lengths and a large list of etceteras, but I dont think it is worthy to post them here. Perhaps with the information  already provided, some of you already has an idea on how to sort out these problems. How do you drive ws2812b over long distances?


texts: Simple Circuit: light source seperated from signal source?

texts:
Forgive me for the simple question!

How would I create a circuit for a light that is switched on when another light is switched on?
Basically I want to use a more powerful source for a new light that is  activated by another light with a smaller source. Something simple that I might be able to solder up.

I'm making a pinball game light modification and I want to grab the signal off of one of the interactive lights, but a more powerful source for a bigger light.


texts:
I am understanding the basics of RS422. Now, consider a driver (RS422) connected to a reciever. Now, we have a termination resistor of about 100Ohms or 120Ohms.

Now, imagine the driver sends out Voc 2V (the differential voltage). Now, if I understand it correctly line A if more positive than line B, then the reciever outputs a logic 1 and vice versa. So, if Vod is 2V, then assuming line A is 2V and Line B is 0V. Please right me if wrong.

In this case there is a 100 Ohm termination resistor. Then shouldnt the current path be from the A line into the termination resistor and back into the driver via the B line.

Is my understanding correct till now.

Now, how does the RS422 receiver work -
The symbol of the receiver(and the driver) is that of an amplifier. SO, I am assuming that it takes in the difference and amplifies the difference thereby acting as a difference amplifier. Now, I was wondering, the whole current will be sunk via the line B into the driver (please understand that I am connecting a driver to a receiver). Now, the amplifier(or in basic an op-amp) has infinite impedance which means that no current is sunk into the input terminals of the  amplifier or rather receiver.

Is my understanding correct on this topic please.


texts: Help me with name of this type of cable to charge my drone.I want usb to female end connector

texts:
I have old remote control helicopter in my toys and I want to charge it via USB.But to purchase it online i am not aware of it's name.Help me with name for connector as shown below. Usb to female end is required.
Cha is mentioned on male end at helicopter.


texts:
I am trying to make LSM6DSR (STEVAL-MKI194V1) work with nRF52840 DK using TWI Communication.

Problem:

Firstly, I modified the TWI sensor example to use the accelerometer (LSM6DSR). When I test my program, I can only see the LED blink. I don’t have any return with NRF_LOG_INFO.

Secondly, I used TWI Scanner example. LSM6DSR is not detected with TWI Scanner example in Nordic SDK15. I don’t have any return with NRF_LOG_INFO.

Background:

I already use the same sensor with an Arduino board without any problem. When I have the problem with nRF52840, I try to add a pull up a resistance, but the result is the same. I used an oscilloscope to see the SCL (CH1) and SDA (CH2) signal for each test with nRF52840. I have the same result the 2 tests.

I also test the Hello example to see if I have the same problem with NRF_LOG_INFO and Its work.


texts: Choosing a transistor for my Raspberry Pi 5v fan

texts:
As I said in the title, I'm looking for a transistor that I could use for switching a Raspberry Pi 5v. fan. The Pi is in an unventilated case, which makes it heat up to 70°C while I would prefer maintaining a cooler temperature of ~45°C. So I'm using a small fan that works perfectly, but is quite noisy when at full load. Because the fan is mounted inside the case, I would have to manually open the case then unplug the fan to stop it. That's why I would prefer being able to control it with a GPIO pin (which is completely doable, I've seen a lot of tutorials about that).

The problem is that the GPIO pin aren't powerful enough to drive the fan (plus it would be dangerous for the Pi itself). So I need to have a transistor acting as a switch controlling the fan power.

I actually have some transistors at hand, but I'm not sure if they are suitable for this use, nor which one of them would fit the best. I'dbe glad if you could help me picking the best transistor, preferably within the ones I already have.

The transistors I have (several pieces in each case) :

2N5462 (Datasheet)
BC308 (Datasheet)
2N4403 (Datasheet)
2N4392 (Datasheet)

The fan is a 1.5cm 2 pins fan running on 5V DC, 0.12A.
I would like to control it using one GPIO pin, which delivers 3.3V.

Thanks in advance for your help !

[IMPORTANT EDIT]
After having searched in my electronical stuff, I discovered that I have a bunch of BC107B transistors (Datasheet), which are NPNs, so the problem is kinda fixed now.

I did some tests with one of them, and at this point, it seems to work perfectly. I can even use PWM to control the speed of the fan. However, before atempting to make anything definitive, I would appreciate if you could tell me if I did everything correctly (ie,i'm not going to damage my Pi).

Here is the circuit I made (extremely simple, maybe too much) :

simulate this circuit – Schematic created using CircuitLab

Can you confirm that the BC107B is suitable for this use ? (I suppose yes, but anyway, I'm not 100% sure that I'm able to understand correctly all the datasheet)
Could I use a small capacitor in parallel with the fan to smooth its power when using PWM ?


texts:
Is there a way to detect if there is a USB cable physically inserted into a USB receptacle, even if it is just a cable (with nothing attached to it).

I am designing a USB charging port (short D+ and D- together styles) and would like to be able to disable the buck converter if there is nothing plugged into the USB receptacle (which will be >99% of the time).

I can't rely on the devices that will be drawing power from the receptacle to have any specific protocol in terms of negotiating charging current etc (i.e. can't use serially transmitted data from device X as a detection mechanism).

I think what I'm asking for is if there are USB-A receptacles with mechanical plug-in detection (along the lines of what is available for SIM cards and SD cards), or if there is a way of "sensing" a plug-in event transient (less inclined to go this route as it sounds pricey).

What say you?

_

_

EDIT:
Found a receptacle with a "contact sense pin" feature that was referenced in another post:

Special USB Port With "Sensor" Contact


texts: Detecting proximity (< 15cm) to a linear device

texts:
Problem: my dogs constantly counter-surf (stand on their back legs to get stuff off of the counter), but they're smart and only do it when nobody is around; it's very difficult to catch them in the act.

Before I try to implement some way of deterring them (but I don't want to shock them), I need to be able to accurately detect when they're doing this.  Given their height, I think the best way would be to somehow detect when their collar is within 10 or 15cm of the edge of the counter.

I'd considered RFID but that would require readers every 20cm or so with their range/power turned way down.

Is there a way to detect when something is within a certain range of a linear device?  I'd like to mount something under the edge of the counter top and when it detects a collar that's in its range, do something (in the short term, that 'do something' will probably be take a picture with a webcam.)


texts: Can an electric motor create torque in a direction opposite to the current axle's spin?

texts:
Let's imagine a wheel spinning clockwise. There's an electric motor on the axle, and we want to spin the wheel counterclockwise.

Can we just switch on the motor and it will work? I want it to slow down, stop, then start spinning counterclockwise. In other words, create torque that's initially in the opposite direction of the axle's current spin. Will this "retrograde" action damage the motor? Or maybe be much less efficient than "prograde" motor operation?

I have no idea if it will be a DC or AC electric motor because I don't really understand the difference between them that well. Does the answer depend on which one? Does it maybe depend on the RPMs involved too?

EDIT: Apparently a motor can be easily used as a generator. I know that will cause countertorque, but this is not exactly what I want. What I'm imagining is an electric power source powering a motor to brake an axle. So the power source will be drained, not charged.


texts: how to stop line wrapping in verilog output from Synopsys Design Compiler

texts:
I'm getting line wrapping in the gate-level verilog file output from Design Compiler.
This is causing problems for Cadence verilog-in.

This seems like it would be easy to stop in Design Compiler, but I don't
see any control switches for the "write_file" command, when I do
"man write_file" in Design Compiler.

So I searched the 2014 Design Compiler User Guide, and did not find anything about
controlling line wrapping. And a Google search did not find anything.

Is there an "attribute" or command that I can set inside DC that controls
line-wrapping on hdl writes ? Note, I can fix this with a perl script,
but prefer to fix this at the source.


texts: Accelerometer to detect when product has been picked up by user

texts:
I have a 3-axis accelerometer on my board and i was hoping to use it to detect when a user lifts the device up.

I would like to avoid false triggers when the table shakes or when the user nudges the device slightly.

I thought this would be a straightforward case of getting the magnitude from all 3 axis (which should on average give me around 1g acceleration) and then low pass filtering it to remove any high frequency noise. Leaving behind the low frequency content of gravity + the motion of lifting the device up. However, it seems a nudge creates a spread of frequncies some of which overlap in the region i am interested in (0Hz - 2 Hz). Any standard filters for accelerometer data?

Can accelerometers be used for such detection? Must i use a different sensor?


texts:
I put together the a Herbie the Mousebot the other day and he is FAST!  Too fast to demonstrate in a small area.

Have a look a this video to see just how he zips around.

Documentation: Mousebot

So my question is - how should i go about slowing him down a bit - so i can demonstrate it in a 1m x 1m area.

Cheers,

Mad_z


texts: How to determine the norton- and thevenin equivalent circuit of this circuit?

texts:
I was wondering how to determine the Norton- and thevenin equivalent circuit for this circuit using superposition. \$R_1=R_2=R_5=100 \Omega, \ \ R4=470 \Omega \ \ R3=330 \Omega\$ \$V_1=10V, V_2=100V\$.

I have managed to derive \$R_T=62 \Omega \$ by setting both voltage sources to \$0V\$.

Through superposition I tried to determine \$V_{OC}\$ and by setting \$V_2=0\$ I obtained \$V_{OC_{1}}=6.14V\$ but I have no idea how to think when setting \$V_1=0\$? What tricks am I allowed to use? Any tips would be appreciated!

/J


texts:
I am using a TPL5110 timer to drive my NodeMCU, in order to keep battery consumption low, but I can't let it work.
I have setup the standard circuit for this timer, as below:

Whenever I apply power from battery, TPL5110 starts blinking without providing power to NodeMCU. If I disconnect the NodeMCU load, the timer works fine. Whatever load I apply to the timer, it performs like it should, except if I connect it to the NodeMCU (which is draining just 80 mA). I have also tried with an opto-isolator, but I got same results: it is like the TPL5110 doesn't like the NodeMCU's load.

I came to the conclusion (after buying 3 TPL5110) that this timer is a cheat for use with NodeMCU. I hope I'm wrong.


texts: Why don't we use the same connector for all digital signals?

texts:
A modern PC typically has a lot of connectors, including USB ports, displayport and HDMI ports, and ethernet ports. My understanding is that all of these are digital connections that are designed for transferring large amounts of data.
Instead of having all of these different connectors, and maintaining multiple independent standards, why not just have, say, 15 USB ports on the back of the computer, and then have all peripherals and networking use this same port as well?


texts: iCEstick40HX1K device is malfunctioned, and windows does not recognize it when programming bitstream on Diamond Programmer 3.5

texts:
I'd designed a " SPI Flash Erase, program,verify with iCEstick 40HX1K. I programmed on Diamond Programmer 3.5. it had done successfully only one time.then i want to reprogram, but when I connect it to my laptop again I see the following message: "USB device not recognized"

Could anyone tell me how to solve this problem?
is the iCEstick device damaged?

Note: I run on windowns 8.1 64bit


texts:
I am working on some circuit lab homework this week and am a bit stumped by something I just can't seem to find anywhere in my Circuit Analysis I book.

The lab has me construct the following circuit on my breadboard:

simulate this circuit – Schematic created using CircuitLab

I then mark down the ammeter and voltmeter readings, taking away one resistor each time until down to one. Using this information, my worksheet asks:

When the LED has current flowing through it, a voltage can be seen across it.  Thus, the LED will have a resistance. Calculate the resistance of the LED for each of the four cases and record your results in Table III

My first thought is R=V/I. But the result just doesn't seem right to me.

Example data I have measured from this circuit with all 4 resistors: 1.586V, 186.2 microAmps. Using these measurements, the LED has a resistance of 8517.72 Ohms? That can't be right can it?


texts: S-matrix of a nonideal directional coupler

texts:
I am investigating nonideal directional couplers, in particular the mathematical constraints between the directivity and other S-matrix parameters. If all ports are matched, it's possible to derive, e.g.,
 \$S_{14}(|S_{13}|^2-|S_{24}|^2)=0\$
No matter what the values of \$S_{13}\$ and \$S_{24}\$ are, this will always hold because of unitarity. See, e.g. Pozar, Microwave Engineering 3rd ed., sec. 7.1, eq. 7.9ff.

I am interested in a more general treatment that does not assume that all ports are matched. I'm especially interested in relating the directivity to the input mismatch \$S_{11}\$. Does anyone have any information on these points?


texts:
Does number of poles always equal to number of zeros in a control system? means if number poles is greater than number of zeros then remaining number of zeros lie at "infinity".
I found this concept in the book "Linear Control Systems, with Matlab Applications: B S Manke". But there is no explanation.


texts: Bad sensor values with D1 Mini v.3 and soil moisture sensor

texts:
I created a simple project using a D1 Mini v.3 connected with a Black 1.2 version soil moisture sensor.
Sensor is connected with 5V and the A0 pin on D1.
When I run this simple example:
void setup() {
  Serial.begin(9600);
}
void loop() {
  int rawValue = analogRead(A0);
  Serial.println(rawValue);

  delay(500);
}

I get 950 in the water and 1024 in the air.
This is a problem because the small range lead to a very unstable measuring.
Is this the normal behavior or I miss something?
Update
I tryied also in real and very wet moist soil:

But values never drops under 952 with 3 different sensors:
1024
1024
1024
952
1024
1024
1024
954
953
952
953
1024
952


texts: Most reliable Flash memory for an embedded Linux system?

texts:
What would be the most reliable Flash memory hardware to use for an embedded Linux system?  I.e. one that has the least chance of losing data or getting corrupt when the power goes down?  The Flash would be for a Linux system so it would need to be at least 2GB in size.  Speed is not super important.  Cost is somewhat important, but not as important as reliability.  Candidate parts would be Compact Flash, raw NAND Flash, eMMC or some other type I'm not aware of.

We currently use micro SD cards but I don't like them, they seem too unreliable and I've had several either become corrupted or just completely die.  Another aspect I don't like is you don't get any visibility into what the card is doing at the lower levels, e.g. how many ECC errors are occurring, how many spare blocks are left etc.

We have a design re-fresh coming up so I wanted to see what the best hardware options would be.


texts: Execute module one after another using flag status

texts:
I want to execute 2 modules, one after another using one flag signal

What changes do I have to do in code below to the modules. I have used delay_4 and multiply.

module iir_model(yout,temp1,win,clk);
  input  [3:0] win;
  output [3:0] yout;
  wire   [3:0] yout;
  input        clk;
  output [3:0] temp1;
  wire   [3:0] temp1;

  delay_4      a1(temp1,win,clk);
  multiply_4  (yout,win,temp1);
endmodule

delay_4:

module delay_4(data_out,data_in,clk);
  input [3:0] data_in;
  input clk;
  output [3:0] data_out;

  reg [3:0] data_out;
  reg [2:0] counter=4'b000;
  reg [3:0] temp;
  reg carry;

  integer i=0;

  always @(posedge clk)
  begin
    i=i+1;
    if(i==1)
      temp=data_in;
    if(i>1)
    begin
      if(counter!=4'b100)
      begin
        carry=temp[0];
        temp=temp>>1'b1;
        temp[3]=carry;
        $monitor ($time," clk=%b,  counter=%b ,temp=%b ,carry=%b,data_out=%b",clk, counter,temp,carry,data_out);
        counter=counter+1;
      end
      data_out=(temp==data_in)?temp:4'b0000;
    end
  end
endmodule

multiply_4:

module multiply_4(z,x,y);
  input  [3:0] x,y;
  output [7:0] z;
  reg    [7:0] t;
  reg    [7:0] z;

  integer i,j;
  always @ (x or y)
  begin
    z = 8'b0;
    for(i = 0; i < 4 ; i = i + 1)
    begin
      t = 8'b0;
      if(y[i])
      begin
        t[i]   = x[0];
        t[i+1] = x[1];
        t[i+2] = x[2];
        t[i+3] = x[3];
      end
      z = z + t;
    end
  end
endmodule


texts: Why am I measuring a voltage on the output of an audio amplifier with no input signal?

texts:
I am working on a small audio amplifier using an NXP 1W BTL mono amplifier (TDA7052).

I've made a quick test circuit on a breadboard using the typical application schematic provided by the datasheet:

I'm currently providing 5V from a regulated supply and have an input signal from the line out (left channel) of a typical stereo receiver.

The sound quality is good and I've used the oscilloscope to look for clipping and set the gain, etc. The 100nF cap is close to the IC as a decoupling cap and all other values are as shown in the schematic.

If I reference ground and connect the scope probe to pin 8 (speaker negative) I measure 2.5 volts DC when no audio signal is present. The flat line turns into a waveform when I introduce a signal, and it works.

I expected the output voltage to be 0 volts when no audio signal is present, from speaker to ground. If I measure across the speaker, from pin 5 to pin 8, I measure between 7 and 80 mV from min to max volume, respectively (as controlled by the pot on pin 4).

Is this correct operation, or do I have a problem to fix?


texts: Circuit analysis to obtain the gain of an inverting Op-Amp

texts:
My problem is that I don't know how to prove that the gain of this circuit is given by the following relation.
\begin{equation}
G=\frac{U_o}{U_i}=-\frac{R_2}{R_1}
\end{equation}
I have the feeling that I'm wrong somewhere in my reasoning, or that I don't understand a key point.

Here is my reasoning so far:

I want to use the superposition theorem, therefore I'm going to analyze separately the two sources (Alternative source, Amplifier).

For the alternative source we have the following.
\begin{cases}
I=I_1=I_2 \\
U_i=(R_1+R_2) \cdot I \quad \text{which means that $R_1$ and $R_2$ are in series}
\end{cases}

For the amplifier we get the following.
\begin{cases}
U_o=(R_2+R_1) \cdot I' \quad \text{where I' is not in the same direction as I}
\end{cases}
From this point, I don't really know where I should go, and I feel that I made a mistake somewhere but I'm not able to tell where and why.

I made some research on this subject, but I didn't find a good explanation.
I have seen some people on Youtube solving this problem, but there always have been some mysterious manipulations that I didn't understand.

Thank you in advance for your responses.

P.S.: I'm not an electrical engineer, but I have an idea of what is an ideal amplificator, and I know Kirchhoff's laws.


texts:
Original document:http://www.st.com/content/ccc/resource/technical/document/data_brief/group0/95/79/2a/ed/d0/a0/4f/46/DM00263698/files/DM00263698.pdf/jcr:content/translations/en.DM00263698.pdf

The screenshot of the schematic:

I can't wrap my head around the PA1 thing. Clearly it's connected to the MCU to have something under control , but what does it do?What's mostly likely its purpose?

Also, when it comes to the PD4 and PD5, is it safe to assume they decide the power in-take from the grid, as in this scenario:

PD4 enabled 25% of a cycle (of the AC sinewave), followed by PD5 enabled 25% of a cycle, then the power in-take will be 50%, if both are enabled back-to-back at 50% then it's equivalent of keep the entire circuit up and going 100%? Sorry for my bad literary skills but I think I managed to get the rough idea through.

If that's the case, then PD3 clearly is for zero-crossing detection, no?


texts: Why switching cause EMI & noise problem?

texts:
I was reading an article topic on "Selecting the correct IC for power supply applications" in which it tells the different types of topology and their pros and cons.In that, it list out the three types of topologies and one of them is inductive switching.

At the end he writes

The switching converter also causes electromagnetic interference (EMI) radiation from
the inductor and noise on the output due to the switching.

So my question is which things are responsible for these interference. Which type of switcher is he talking about? It's a little bit complicated for me to understand.I even search it on web but didn't get any document that helps me.


texts: Extension from OLED display to driver board

texts:
I have purchased this display for a prototype in development.
Product: https://www.displaymodule.com/collections/oled/products/2-8-256x64-monochrome-graphic-oled-display-module-spi-mpu
Datasheet: https://drive.google.com/file/d/1gxOVcEEhbBCdMktJI8cXT_XhS1yv98Ft/view
Due to the limitations in the assembly of the prototype, the screen needs to be separated from the board. Because of the orientation of the parts, this means the FPC (apologies if this is the wrong term) cable cannot reach the connector on the board (see image, white tab is back of connector from screen, needs to get to receiver on blue board).

I need to source a female to male extension for this to make the assembly feasible, but do not have good knowledge with this type of connector.
Is anyone able to provide advice on what type of extension I could utilise and where it can be sourced from?
Please let me know if any further details are required.


texts: HowTo create an accurate constant-current dummy load using immersion heaters controlled by Arduino?

texts:
Given: variable sized nominal 3.2V LI/LFP battery cells, from little 18650 / 26650 cylindrical A123s up to large prismatics from CALB / Winston etc.

the desire to capacity-test them off grid (no mains power available) as accurately as possible*. Ideally many cells at a time, so with low-cost equipment, namely

a DIY adjustable constant-current load
timestamped data-logging of V & A, likely Arduino based
a LVC set just below the test's stop point to protect the cell from over-discharge
a shunt-based or Hall effect coulometer for sanity check calibration

This query is really just about the first item please. I realize I could use nichrome, or even fencing wire, but I would prefer a safer looking, less fragile and compact self-contained load dump, as this rig will be used in a mobile context, and will need to sometimes travel with me by air.

My idea for variable resistance is OTS immersion water heater elements, inserted via threaded ports into a smallish water tank, possibly if needed with in/outlets to circulate water from a larger one, or perhaps a body of water for infinite heat dissipation, the test may run for up to 20 hours with large enough cells.

The range of power used needs to be variable, from below 10W/3A up to 500W/160A (0.3C or lower discharge rate). I see low power elements at 12V, higher wattages available in 24V 36V and 48V, but I believe the low cell voltage 3-4V will require lots of 12V units?

So far so good? Now the part I really dunno. What sort of (likely Arduino based?) control circuit could precisely vary either the voltage (PWM?) or the resistance? so as to keep the amps pulled from the cell by the heater elements (as accurately as possible, *say 0.5 - 1% using Ah) at a constant current?


texts: How do I manipulate a potentiometer over a wireless connection?

texts:
Hi and thanks for looking!
Background
I am building a RC multicopter using a KK controller.
The controller has three potmeters to control gain/sensitivity for pitch, roll, and yaw channels.
Since I wanted to seal the controller in a canopy, I have already removed the potmeters and in their place wired three thumbwheel potmeters to the outside of the canopy so that I can adjust the gain as necessary.
This works fine.
Question
I already am using three channels on my transmitter (each mapped to a trim knob) to talk to a separate circuit on the aircraft. Is there a way that I can use these three channels to adjust the pitch, roll, and yaw gains wirelessly?  Would I use a transistor in place of a potmeter?
I can use Arduino & etch a small PCB to accomplish this if necessary, I am just not sure what components to use.
Thanks!


texts: Maximum peak current swing (Class A amplifier)

texts:
For a class A amplifier, the Q point is centered as shown:

and the maximum signal that can be obtained is when the peak value of the current is Icq and peak value of VCE is VCEQ

Now when we calculate the 'maximum peak voltage swing' and the 'maximum peak current swing' This is what the book does

We just said that the peak value of the collector current is Icq in the second picture, so why is it that Ic(max) = VCEQ/Rc  in the last picture?

Same with Vc(max), what's the difference here?

Also, if there is no difference, why do we divide VCEQ by Rc to get collector current?

note: Rc is the ac collector resistance, Vc is the collector voltage, from floyd's electronic devices ninth edition page 343


texts:
Many designs of coils, of metal detectors, are shielded (Faraday shield).

Should this be used in a gravity-fed detector (like the sketched one)?
What's the shield for?

NOTE:

The coils are arranged inside a metalic cabinet, which is grounded.


texts: Improved power factor effect on national grid

texts:
I was wondering what the effect would be on the national grid for if a large power consumer was to improve its power factor.

I know that it would reduce demand but is there any other effects?


texts: Power adapter sparks and then stop working

texts:
I have an Asus X550C laptop, and I have troubles with his power adapter. The power adapter is 19V, 3.42 A, 65 W. Every time when I plug in power adapter in outlet, there is a little spark but it works fine. Sometimes, that spark is huge, and my power adapter stops charging. I found one way to fix this issue, temporary, like that: I opened the plastic case, and I took that electrical circuit in my hands,  I dropped it on the floor (by mistake) , then I assembled my power adapter, plugged it into outlet (I have wondered if it works) and surprise, it works until that huge spark comes out again, and I need to drop it on the floor to make it work. I know this is not a good ideea, but I need laptop  because I need to work with it. Untill my new charger arrives (2-3 days) I am using this "dropping technique" to make it work.

And my question is, why my power adapter stops charging everytime when that huge spark comes out? May be an issue with the capacitor? Or there is not good connection between the wires?


texts: Understanding CT sensors and current to voltage circuits

texts:
I have difficulties to wrap my head around the concept of CT sensors (SCT-013-000 f.e.).
I currently want to improve the current to voltage circuit I use with the usage of an op amp. While I can just copy the existing circuit designs out there and use them I would rather have a deeper understanding.

From what I understand the coil in the "sensor" is getting current induced by the AC phase I clamp it onto.
Though I don't have any voltage which weirds me out, do I just have electrons just sitting around in the coil? Where do they go? Can I build up a lethal amount of current by not connecting it to a circuit?

Apparently I need a so called burden resistor across both ends of the CT sensor to get a voltage but how does that work? Why does a resistor make electrons flow all of the sudden?

How can I use this CT sensor that gives me current but no voltage without violating ohms law? I get more amps all of the sudden than my power supply is delivering to the circuit. Or is my PSU delivering an equal amount less than gets induced by the CT sensor?

I'm deeply confused by this concept of a current only source and how I can turn this current into an equivalent voltage, maybe someone can shed some light on this for me.


texts: Is there a way to determine the pull-down resistance of a FPGA pin?

texts:
I have an FPGA and don't have access to the code used to program it. The data sheet specifies that you can configure pull-down resistors that vary from 50-100 ohms.

Can you measure the value of a pull-down resistor inside an FPGA? If so, how?


texts:
This Question is regarding to Transformer Power Electronics. I attached two transformers - one is Step Up (220V ; 0.5A) and another is Step Down (6V; 20A) to a same power source (25V ; 5A) in such away that both transformer gets input current alternately. In simple words only one transformer is active at a time and another is off.

So My question is here I am getting two outputs from two transformer alternately. Now I want to add up both output so that the final output must be the constant i.e (250V; 20A). Can anybody tell me that how to add both voltage?

I have some idea in my mind i.e converting both voltage to DC and then add or using RLC circuit in both transformer to get constant output and then add it.


texts: When do we use minterm over maxterm in real words example or vice versa?

texts:
This may sound stupid. We have minterms. It is a product of all variables in a function and that function has the property that it is equal to 1 on exactly one row of the truth table.
What do we call if we have a product of all variables in a function and that function has the property that it is equal to 0 on exactly one row of the truth table?
On the other hand, We have maxterms. It is a sum of all variables in a function and that function has the property that it is equal to 0 on exactly one row of that truth table.
also, What if we call it if we have a sum of all variables in a function and that function has the property that it is equal to 1 on exactly one row of the truth table?


texts: Debugging a 16x2 LCD Display on an Arduino

texts:
I have a standard 16x2 LCD display (I believe it is Hitachi HD44780 compatible - see summary and specification below), hooked to an Arduino Uno using 4 data pins, as described here, though I've added 2x 220ohm resisters in parallel (ie a 110ohm resistor) on pin 16 (Backlight ground), and replaced the Pot with static resistors to create 4V on Vo.

In short, RW is wired to ground, and RS, Enable, and Data4-7 are connected to Arduino pins, while Data 0-3 are floating.

I have other things (sensors, a transistor with an optoisolated SSR and a mains relay, some buttons) connected to different pins on the Arduino. The code I use writes text to the display a number of times a second, and normally, the display works perfectly.

However, when the relay closes (it takes about 10ma, and is controlled by a transistor which is in turn controlled from one of the Arduino pins), sometimes the LCD becomes garbled. It remains garbled usually until the relay next closes, but sometimes when the relay opens, or after a few more cycles of open/close to reset. The garbling always starts and stops at the same time as the relay either opens or closes.

By "garbled", I mean that every time I write to it following it becoming garbled, rather than writing english characters, I get a string of characters, that I usually cannot identify in the datasheet (though some I can). This string of garbled characters tends to move left along the screen as I write new text to the LCD.

I am confident it's not the Arduino itself getting confused, as I write the same text to the Serial monitor at the same time, and it is not garbled.

I've since experimented with wiring the RW pin to an Arduino output, and Data0-3 to ground, but this doesn't help. I've powered the whole device with a 9V battery or with USB, and it doesn't help. I've replaced the battery... no change.

The only thing that seems to work is having no load plugged in to the relay, but that defeats the purpose :-)

I don't have a signal analyser or anything more sophisticated than a multimeter, a laptop and an arduino... Does anyone have any hints for helping me debug this?

LCD Summary Sheet: http://oomlout.com/LCDD/LCDD-SUMM-BC1602A.pdf

LCD Specification: http://oomlout.com/LCDD/LCDD-DATA-BC1602A.pdf

Example of garbled text:


texts: How to improve reception in a wireless CCTV system?

texts:
I have a 2.4Ghz wireless CCTV system just purchased for my barn. The system is a Uniden UDR444 with two cameras. The barn is 200' from the house, where I need to monitor the camerasin the barn. Uniden claim 'up to 500' range'. I can't get the cameras to link from more than 180' away, which coincidentally right before I walk in the house door. As soon as I walk in, the signal is lost.

The house is a log cabin, and the barn is a wooden framed post barn with thin steel cladding. Obstructions to line of sight between camera and receiver are 1) 2"x4" barn roof truss, (doesn't matter which side of it camera goes) 2) Thin steel barn siding, 3) log cabin wall. I can get a 'four bars' (max) signal right up to the house, but camera goes 'out of range' as soon as I either go in the house, or even if I put the receiver through the window into the house behind the glass.

Should I get different antennae for the cameras? They have standard threaded antennae mounted to the back, about 4" long, but the receiver antenna is fixed to the remote viewing 'pad' and can't be changed, short of hinging it up, which I've tried. I've found 15" 9DBi antennae. Will that help or am I always going to be fighting the steel barn?


texts: Need suggestions about a narrow bandpass filter design

texts:
I am now designing a narrow bandpass filter. Requirements are shown below:

Center frequency is about 2kHz(10% flutuation is OK). The gain of center frequency is about 34dB(the higher the better,up to 65dB). The difference of gain between 2kHz signal and 1kHz signal(or half of the center frequency) needs to be not less than 43dB.

My current design is to use the MFB topology to build up a two-stage/four-order bandpass filter.

Is such design OK? Or any other better topology or method?

Addition:
The simulation result is

Center frequency at 1.999kHz;
Gain@2kHz is 34dB;
Gain@1kHz is -12dB;
The phase margin of each stage is higher than 45 degree(test by middlebrook method)


texts: I working on a coil gun for a demonstration on electromagnetism. I have 2 stages, each with 2 1400uF 450v capacitors that I will be charging up to 375v. I am looking for a switch, or something to the same effect, that can withstand that current and voltage when discharged to the coils. I was also thinking about using an arduino to activate a transistor that can also withstand that current and voltage when the projectile reaches the second stage. Is there a good switch and/or transistor I could use for this? And is the arduino the best thing to use to activate the second stage, or should I use something like a photo-transistor or photo-diode?


texts:
I am seeking advice/validation for powering a long length of LED strips. I know it's a lot of questions so I'm grateful for any feedback on any of this.
I'm planning to run about 37m of strip lights around the perimeter under a deck as such:

Strip: SK6812 60led/m (5V) as I want addressable RGB+W.  As far as I can tell nothing similar in higher voltage, so needs to be 5V.
37m total * 60 LEDs/m = 2200 LEDs
Seller published max power draw for 60/m is 18W/m, so 37 * 18 = 666W (I've seen actual measurements that suggest more like 15W/m or 555W)
PSUs/controller will be inside house near point A in diagram

My general plan would be to use multiple power supplies and separate run(s) to inject where necessary. I realize this may be a little over the top for 5V but hoping it's feasible.  If it's too crazy I could fall back to 30LED/m and cut it in almost in half, but would ideally like to do something like this if possible.
Questions:

Are my power calculations correct and does 666W represent total wattage required from PSUs?
How many power supplies and would a unit(s) like Meanwell RPS-320 suffice?
At what intervals would I need to inject (to get max white)?  I've read as much as every 2.5m
What size wire for separate injector?
Any advice on cabling to optimally hit injection points based on the layout?
Any advice on making the connections to injection points?  Do  I have to cut the injector line and solder both ends to points on the strip?
How do I calculate current draw on the circuit powering the PSUs.  If it's 120/15A circuit how much capacity would be needed max?
Is it an omen that my power requirements for this just happen to be 666W?

Thanks!