texts:
NAND-based digital flash data storage devices such as SD,SSD,USBstick,eMMC,UFS,etc. do have transistors, where the small amount of electrical charge does slowly leak over time, resulting into data loss when inactive for excessive time spans. Heat does accelerate that process.

In order to recharge the transistors, do I need to actually read the data like on HDDs, or does the storage just need electrical power supply?

And if the latter one is true, how many seconds or minutes does the NAND storage need power supply? Does 5.3V instead of 4.9V make any difference?


texts:
I am using a MEMS Accelerometer (ADXL1001), along with the EVAL board and an NI 9234 DAQ module to acquire the signal. I am using a RG58 coaxial cable to connect the sensor output (2 connector pins, Vout and Ground on the EVAL board) to the DAQ input (BNC connector).

However, I noticed that there's an interference and I see a small peak at 50 Hz frequency in the FFT of the signal (since the signal cable was lying near to a power amplifier). And on shutting the power amplifier OFF, the peak disappeared (no surprise).

My question is, which type of cable should be used (coaxial, shielded twisted pair or any other?) to achieve the best noise performance and to make sure that there's (almost) no interference.

Some addtional information:

*The sensor measures frequencies up to 20 kHz and the voltage varies from 0 to 5 volts, so the cable should be accordingly.
*The DAQ (NI 9234) has a pseudo-differential configuration). (Does that impact the type of cable that can be used?)

Thanks in advance :)


texts: Power load and source questions (music controller with led strip load)

texts:
This is power source (a music controller) for a project

This LED strip is a 72WATT load. My power calculations are 216W-72W=144W. So I have 144w remaining to use (thats my understanding)
[![enter image description here][3]][3]

How did they used this kind of adapter if they are short with 12watts?

2nd question: If A power device can source more watts than (mine with 216w). Could I use two loads (like an led strip) at the same time?

3rd question: What if a source has lower watts than the load?


texts:
The datasheets for the FT232H chip are readily useful for interfacing a USB (5V) powered FT232 to any 3.3 volt RS232 (TTL-ish, at 3.3V) device, and for powering the FT232H with 3.3V. In both cases, one is instructed how to provide the VCCIO{1,2,3} pins with 3.3V. (Been there, done that!)
However, I can't make out from the datasheets if this allows me to interface the FT232H with a device operating at 1.8 volts by supplying 1.8V to the VCCIOn pins, or if I must power these pins with 3.3V and use a level converter.
Can I supply the VCCIO pins with the 1.8V of some target device and aassume that the FT232H chip applies an 1.8V logic?


texts: Can you speed up debugging in Renesas High Performance Embedded Workshop by not flashing after breakpoint

texts:
I am debugging an H8S MCU in Renesas High Performance Embedded Workshop 4 with the attached E10A emulator, and find it's very slow when stepping through code because it keeps reflashing the chip between some lines, but not all.

I could understand it reflashing if I change breakpoints, but not when there are no changes at all.

This is what the debug panel shows after a a bit of stepping, most of the flashing are after using F10 just to go the next line.

Each reflashing takes up to 10 seconds.

RUNNING
BREAK KEY
 Flash memory writing ...
 Flash memory write end
RUNNING
BREAK POINT
 Flash memory writing ...
 Flash memory write end
RUNNING
 Flash memory writing ...
 Flash memory write end
BREAK POINT
 Flash memory writing ...
 Flash memory write end
STOP ADDRESS
STOP ADDRESS
STOP ADDRESS
 Flash memory writing ...
 Flash memory write end
STOP ADDRESS
 Flash memory writing ...
 Flash memory write end
RUNNING

I'm sure at one point I got it to stop doing this and it just stepped instantly, but I seem to have lost the setting.

Before I spend hours trying to solve it, I wondered if anyone knows if this is just how it is?


texts: How to latch a signal rise and low on the next signal rise

texts:
My input signal is a pulsing 35Hz with a top at 5 volts. The pulses itself are short.
The first pulse (5v) should trigger a latch at 5v high. And the next pulse should reset the latch to low.
Added a illustration below to make it more clear. Who can point me in the right direction?


texts: Half-H bridge or low-side MOSFET for PWM motor control

texts:
I'm driving a DC motor (12 V, approx. 4 A) and I need to control the speed by PWM but I need one direction only and braking is not required.

My question is: is there any advantage to using a half-H bridge over using a simple low-side N-channel MOSFET (e.g. a IRLS3034-7PPbF)?

I'll be using a MOSFET driver (IXDN404 or similar) in order to switch fast enough and provide enough current to the gate and the PWM will be generated by an MCU.


texts:
I'm having problem with triac handling. The plan is to use it to drive traffic light signals. The trigger is fine, but I want to use the hold current as a burnt bulb detector. Meaning, if the current goes under the holding threshold (ie: the bulb's filament is burned), the triac should go off.

What I don't understand, is why the triac doesn't go off after the pulse, even if the triac's output is completely open (disconnected). From my understanding, if there is not current flowing between A1 and A2, the triac should go off. The yellow line is the gate pulse, the blue line is the output of the U5 opto.

What am I doing wrong?

The optotriac is MOC3083

The triac is T1623-600G

The optocoupler is LTV-354T


texts:
I have some ATX PSU with passive PFC (huge coil with capacitor).
I also have some active PFC from other ATX that based on L6561 IC.

This psu will handle odroid xu4 board and few led strips based on ws2812b chip.

I have limited space in this box and probably will need remove this passive coil or use this active board...

Can I replace it, or is there something that block this idea?

P.S.

Picture of boards:

Best Regards.


texts:
I am planning to build an electric bike powered by a 12S LiPo battery, and I am trying to decide how I should implement monitoring of the individual cell voltages. Manufacturers like TI provide a decent selection of chips for battery monitoring which include balancing functions, although I will not need this functionality as I will connect the battery to a balance charger when not in use. With MCUs being available for ~$1 with plenty of ADC channels, it seems tough to justify spending $7 or upwards on a TI chip when I could implement basic ADC reading and communications on a MCU (not to mention I could easily implement some kind of differential signalling to run over long wires in the vehicle, where the I2C or SPI native to the TI chips would require some kind of buffer).

I would like some seconds opinions on this. Is there any other sort of advantage to off-the-shelf battery monitor chips I should be aware of, other than convenience (and perhaps peace of mind in that if I roll my own solution, I have to make sure my code is reliable in every situation)?


texts: Which antenna to use if close proximity to metal objects is unavoidable?

texts:
In my application, the device is going to be placed on top of a metal disc, less than a centimeter away from the pcb!

Now I have prototyped up the device using a nRF24L01+ breakout board with only a chip antenna, and I can communicate with the device from a few meters away (obviously from a receiver with line of sight to the PCB, not from underneath the disc). However, if I want to enhance my design and enhance the reliability of the wireless link what kind of antenna should I use?

Should I switch to a lower RF frequency band?

From what I have read around the internet, a patch antenna with a ground plane underneath might be a good antenna to use, because the effects of the metal disc underneath the whole pcb will be reduced since our design involves a ground plane underneath the antenna anyway. This seems to take up a lot of space as opposed to a IFA antenna etched directly on a pcb.

However, being quite new to all this RF theory, I basically don't really have a clue. Any ideas?


texts: Can a 6 volt positive ground system share a common chassis ground with a 12 volt negative grd

texts:
I am working on an antique car that has a 6 volt positive ground electrical system with the exception of the fuel gauge which is a 12 volt negative ground. Currently the car has a voltage converter that takes a 5-11v input and converts it to a steady 12 volt output. However, the -6v supplied by the cars electrical system results in an output of only 5.65 volts from the converter. If I supply +6v (external adjustable DC power supply) the converter will output the steady 12v. I have found a few voltage converters online that state they convert a 6 volt positive ground input into a 12v negative ground output. The first has only 3 wires, the -6v input from the cars electrical system, the +12v ouput and a ground to chassis. The sending unit for the fuel gauge (variable resistor attached to a float) has 2 connections, one back to the gauge and the other to ground.

My questions: Can the sending unit be grounded to the car's chassis which also has a 6 volt positive ground electrical system connected to it? Can the two dissimilar voltages and polarities exist with a common chassis ground?


texts:
I'm driving an ILI9230 LCD 320*240 16bit interface, with a framebuffer of 250*200 and I want to drive it as 4bit. so I built a loook up color table like that:

u16 LUT[16] = {
    //0      1      2     3    4    5    6    7    8
    BLACK, BRIGHTRED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE,
    // 9      A    B      C    D     E   F
    BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE
};

then my framebuffer is an array like that:

#define fbWidth      256
#define fbHeight     200
char frameBuffer[fbWidth*fbHeight/2]; // 256*200*4bit

I try to swap the double buffers like that:

for(i=0;i< fbWidth*fbHeight/2;i++)
        {
         u16 color = LUT[frameBuffer[i]];
         *(__IO uint16_t *) (Bank1_LCD_D)= color;
        }

and to write to the backbuffer:

    // color is 2
frameBuffer[fbWidth * y + x] = color;

The problem is I get less screen resolution due to truncating the frramebuffer width*height/2.. looks like I didn't implement the look up color table concept not correctly..


texts: How do analyze input impedance of Class AB amplifier biased with resistors?

texts:
EDIT: I realize that the original circuit is deeply flawed and will burn up upon re-entry.  Thanks to anyone who can help me understand why!
I'm learning to analyze Class AB amplifiers, but haven't found a good source with information on how to determine their input impedance.  I built this circuit as an example.  It's a simple Class AB amplifier with resistors to overcome crossover distortion.  I would love feedback on whether my understanding of \$R_{in}\$ is correct.  I assumed both transistors have a \$\beta=50\$.

As far as I can tell, \$V_S\$ will see two branches: first, it will see the \$60\Omega\$ R2 in series with the parallel combination of R1 and the impedance looking into the base of Q1; in the other branch, it sees \$60\Omega\$ from R3 in series with the parallel combination of R4 and the base of Q2. So an equation like the following should work, yes?
$$R_{in}=(R_2+(R_1||R_{ibQ1}))||(R_3+R_4 || (R_{ibQ2}))$$
I started with the Q1 branch.  First I found \$r_e\$.  \$I_C\$ fluctuates between 2.6mA and 2.7mA, giving a very small value for \$r_e=25mv/2.6mA=9.62\Omega\$.  With this in mind I can solve for \$R_{ibQ1}=\beta*(r_e+R_L)=50*(1000+9.62)=50,481\Omega\$.
\$R_{ibQ1}\$ is in parallel with R1 and that combination is in series with R2, so the entire Q1 branch of the circuit is
$$R_{Q1branch}=60\Omega+(1000\Omega||50481\Omega)=1040\Omega$$
From here I'd like to think it's as easy as imagining the Q2 half of the circuit as equivalent in impedance.  The total input impedance of the circuit, then, is half of the previous calculation, or \$R_{in}=1040||1040\Omega = 520\Omega\$
I'm sure this isn't exactly correct, as it seems way too simple to only solve half the circuit.  I'd love to hear all the ways I've been led astray.  Please note that this is not an amplifier I imagine has any real purpose, just one that works enough to help me understand how to analyze its input impedance.


texts: Does the Shockley diode equation apply to Schottky diodes and non-silicon diodes?

texts:
As I'm sure most people here know, the Shockley diode equation is
$$ I_d=I_s[e^{\frac{V_d}{nV_t}}-1] $$
Notice that none of the quantities here other than \$I_s\$ and \$n\$ are dependent on the diode itself. \$n\$ varies widely even sticking to just silicon diodes, so clearly the different voltage drop of other diode types can't be adequately explained by that.
Is the variance in \$I_s\$ alone adequate to describe Schottky junctions or diodes of other semiconductors (like GaAs or SiC or the wide range of LED semiconductors), to the same accuracy that the equation describes silicon diodes? Or is there some assumption built into the equation that makes it only valid for silicon diodes? Can \$n\$ be far outside the [1,2] range it's commonly cited as being restricted to, in non-silicon diodes? Are there dropped terms that are very small for silicon diodes that are non-negligible for other types?


texts: Amperage and Voltage Question: The Water Pipe Analogy

texts:
Since Voltage is like water pressure, and Amperage is like the volume of water being pumped, in a given hose (wire), there's a volume threshold based upon its diameter (AWG), but only in relation to the pressure applied (V).

So, if I pour water into a closed end hose, it will fill up and spill out.  There is very little or no pressure at all.  Just gravity.

If I add pressure, I create friction, the hose expands by resisting the pressure (light slowly fades in).  Of course, it's a hose, and it has water in it, and therefore it probably won't catch on fire from friction.  If I add too much pressure for the hose (AWG) it will burst.  If it was a wire, it would heat up and turn into a light saber, which would be great for an oven, or a foam cutter, or a distant galaxy far, far away.

Am I on the right track?

So, the relationship between applied current and burning your house down correlates to the thickness of your wire (whether it's solid or stranded, what material it's made of, etc.,) and the amount of current you apply to that wire.

QUESTION PART:

Where I'm confused is how amperage works.  In a hose, or a water line, for example, each outlet valve reduces the volume of water being sent to the next valve until the pressure is reduced to nothing.  If we want the pressure to remain constant, we would need to reduce the pipe diameter as the line continues.

In electricity, it seems like it's similar, only the electrical devices draw amperage...yes?  Wouldn't that be like adding a pump to the main water line to pump already pressurized water out of the pipe, in which case, if we did, we may deplete the water line too quickly, causing it to collapse...

Is that what's happening when we fire up too many devices that draw more amperage than the breaker can handle?


texts:
Conservation of Charge states that "Charge cannot be created neither be destroyed."

If something cannot be created, then how it is in existence?


texts:
I'm working on a project where I have to communicate different lengths command from my PC to a microcontroller. (using usb to uart bridge)
I already make a litle protocol (start byte, some data, checksum ...) but I need to adapt it for my new need.

I'm wondering if there is already a standard or a common way to do that.


texts: Will a 78S12 be cooler than a 7812 when handling the same load?

texts: Given of course that both come in a TO-220 case. I wouldn't think so, right? I try to make it out from the K/W ratings but they seem to vary wildly from manufacturer to manufacturer. Anybody knows the answer?


texts: Does this coil topology work at high frequencies?

texts:
I have a cast iron wok and an induction hob. My understanding is that a ~24kHz AC in the hob's coil causes heating in the wok due to eddy currents from the varying magnetic field.

Sadly, the iron needs to be very close to the coil to work, and as such only the bottom part of the wok gets heated. I would like to heat a bit more than just a small part in the middle, and also be able to take advantage from the 'boost' ring which is otherwise out of reach of the wok. The basic idea is schematically depicted below, but I would like some advice on whether this topology would work, and if there are any additional considerations given the relatively high frequency.

The idea is to have a pancake coil wound of Litz wire placed just above the induction hob's 'boost' ring. This would be connected to a second, conical pancake coil (also made from Litz wire keeping in mind the skin effect) that is positioned very close to the pan to heat it inductively (while keeping the coil relatively cool).

Does the winding direction of the 'second' coil matter? My intuition was to place it reversed w.r.t. the bottom ring to 'push' the magnetic field more in the pan,  but perhaps this actually reduces the efficiency by reducing the induction and thus the current? Should I worry about any side effects? (I presume the cooker works as an oscillating tank circuit, so perhaps a secondary coil would mess up the expected inductance of the circuit)


texts: Using current divider to see how much current goes inside the plane when lightning strike

texts:
I am working on a project that requires me to understand how engineers do current analysis. The aircraft has a metallic body which provides a path for lightning when it strikes but what if there is an object hanging outside the plane, how do they determine the amount of current flowing inside the plane. Lets say that certain amount of current has latched onto the cable of the object and flows inside the plane.

The only method I can think of is current divider.
What other method can help determine that current flowing inside the plane.
I hope it's not that complicated.


texts: Using method of image to find surface charge density

texts:
Two point charges of 50nC and -20nC are located at (-3,2,4) and (1,0,5) above the conducting ground plane z=2. Calculate: a)The surface charge density at (7,-2,2), b)\$\vec D\$ at (1,1,1)
Now, according to method of image there are \$50\$nC charge at \$(-3,2,4)\$ and \$-50\$nC charge at \$(-3,2,0)\$.
For, 50nC charge,
\$\begin{align}\\
\vec R_1&{\begin{aligned}\\
=7\hat a_x-2\hat a_y+2\hat a_z&-(-3\hat a_x+2\hat a_y+4\hat a_z)\\
\end{aligned}\\}\\
&=10\hat a_x-4\hat a_y-2\hat a_z\\
\end{align}\\\$
For -50nC charge,
\$\begin{align}\\
\vec R_2&{\begin{aligned}\\
=7\hat a_x-2\hat a_y+2\hat a_z&-(-3\hat a_x+2\hat a_y)\\
\end{aligned}\\}\\
&=10\hat a_x-4\hat a_y+2\hat a_z\\
\end{align}\\\$
\$\begin{align}\\
\therefore\vec D&=\frac{1}{4\pi}\left[\frac{50\times 10^{-9}(10\hat a_x-4\hat a_y-2\hat a_z)}{[10^2+(-4)^2+(-2)^2]^{3/2}}-\frac{50\times 10^{-9}(10\hat a_x-4\hat a_y+2\hat a_z)}{[10^2+(-4)^2+2^2]^{3/2}}\right]\\
&=-12.11\hat a_z\times 10^{-12}\\
\end{align}\\\$
Again, according to method of image there are \$-20\$nC charge at \$(1,0,5)\$ and \$20\$nC charge at \$(1,0,-1)\$.
For -20nC charge,
\$\begin{align}\\
\vec R_1&=7\hat a_x-2\hat a_y+2\hat a_z-(\hat a_x+5\hat a_z)\\
&=6\hat a_x-2\hat a_y-3\hat a_z\\
\end{align}\\\$
\$\begin{align}\\
\vec R_2&=7\hat a_x-2\hat a_y+2\hat a_z-(\hat a_x-\hat a_z)\\
&=6\hat a_x-2\hat a_y+3\hat a_z\\
\end{align}\\\$
\$\begin{align}\\
\therefore\vec D&=\frac{1}{4\pi}\left[-\frac{20\times 10^{-9}(6\hat a_x-2\hat a_y-3\hat a_z)}{[6^2+(-2)^2+(-3)^2]^{3/2}}+\frac{20\times 10^{-9}(6\hat a_x-2\hat a_y+3\hat a_z)}{[6^2+(-2)^2+3^2]^{3/2}}\right]\\
&=27.84\hat a_z\times 10^{-12}\\
\end{align}\\\$
\$\therefore\$ Total
\$\vec D=15.73\hat a_z\times 10^{-12}\$
We know, surface charge density
\$\sigma=\vec D.\hat a_n\$
Now, as the point is on the plane I can't understand what will be the normal vector \$(\hat a_n)\$, upward or downward. Please anyone help. (The answer is \$6.41\times 10^{-12}\$)


texts: Why is ISS photo-voltaic current output shown as a negative value?

texts: Looking at raw telemetry data provided by NASA from the ISS (here's a nicely formatted version: https://isslive.com/displays/spartanDisplay1.html), the current output of the photo-voltaic panels are shown as a negative value. Maybe there's a simple explanation for this, but I haven't found any information on it (one NASA "teaching guide" I found talked about calculating PV power output from this data and essentially ignored the negative sign). I can see why voltage might be negative, but not current--after all, the PVs are generating power, not consuming it. Any thoughts?


texts: Should FPGA interface an IC using more than one IO bank?

texts:
I would like to interface a FPGA with a fairly fast IC. My FPGA is MachXO2-7000HC while the IC in question is FTDI's FT601, which is a USB 3.0 to FIFO bridge.

The FT601 has quite a few control/data signals, totaling 42 signals (32 data lines plus 10 control signals used for controlling the actual transactions). The data lines are bidirectional and the incoming clock from the FT601 is 100 MHz, which is quite fast.

I am using the MachXO2 TQFP-144 version, which consists of 6 banks, 1 at the top, right and bottom and 3 at the Left side. My original plan was to interface with this IC using Bank 1, which resides at the right of the MachXO2 FPGA chip.

Then, I realized that each bank at Top, Left and Bottom consists of 27-29 I/Os which are less than those required by the FT601, so I will have to "borrow" some I/Os from a neighbor bank.

So my questions are:

Is it legitimate to use two different banks to interface with an IC?
Is it considered a generally safe practice or should be avoided?
Is it going to affect the IO speed somehow since those are different banks?

I am worried since the IC has high speed requirements plus a large number of data and control lines.

Of course both banks will be configured with the same power source as well as the same I/O Type. (FT601 uses 3.3V bidirectional I/Os, outputs 100 MHz for the controller [FPGA], Single Data Rate)

Lastly, I carefully studied both the MachXO2 Family Datasheet as well as the MachXO2 sysIO Usage Guide and did not read anything that explicitly discourage it or a section that implies that it will cause any issues.

Thanks in advance.


texts: I just want to know what exactly input impedance is with respect to the  diagram below. And the second thing is obvious, how do we calculate it.


texts: 4 bit to 4 bit subtractor logic gates problem

texts:
I'm trying to create a 4 bit by 4 bit subtractor here but I get wrong output. In the picture it shows that 0000-1111=10001 which should be 0000-1111=11111. Please help me.
By the way the rightmost IC is a half subtractor and the remaining three are full subtractor.


texts: Is there any difference between a low pass filter and a lag compensator?


texts:
What are the guidlines (or where can I find them) for which products require EMC testing certificate? I know that this determined per country, so for starters let's go with the US.
My product contains a LIPO 3.7v battery, vibration motor, processor and accelerometer, no wireless transmission whatsoever. Will I need to have it tested?


texts: Powering Arduino from same battery it is sensing (Positively grounded)

texts:
I've got an arduino that is monitoring voltage and current on a solar charge controller. V & I for panel, battery & load.

Background:
The charge controller that is being monitored by the arduino has a common positive, so in order to measure multiple terminals at once (more than just the battery, or just the load etc.) I need to set the arduino ground to the common positive voltage, and measure the negatives of each terminal. With the help of some of you guys I've managed to use the +5V from arduino to create a voltage divider that lets me sense this (negative) voltage relatively accurately as a positive voltage coming into the arduino.

Now what I am trying to do is, instead of powering the arduino with an external power supply, power it with the same battery that is being sensed. The problem I see is because I'm using the battery (~+12V common positive terminal) as ground in arduino, if I use a buck to step down voltage to (9V) I am actually putting in -3V. This was confirmed by frying one of my arduinos. Either that's what happened or because the grounds of the arduino are connected, when I put in +9v into the terminals, I connected battery black to Gnd, and when I connected the common positive to GND, I connected battery red to Gnd effectively causing a short. ?  Next test would be to step up with a boost to ~+22V and then put that into the arduino giving me a net +10V for arduino. But I imagine this is not a good idea.

Any ideas for how to successfully power this positively grounded arduino with the same battery it is sensing would be greatly appreciated!!


texts: Ideal CUK converter design problem in LTSpice

texts:
I am trying to simulate an idead Cuk converter. The circuit parameters are taken from Power Electronics, D.W.Hart, page 230. I set the following circuit:

I try to do a transient analysis. I also try to change T_on value and observe the change in the output voltage. But simulation graph shows the following for output voltage:

What is wrong with the simulation set up?


texts:
I'm working with a 11 kV capacitor bank and is trying to calculate (by hand) the I0 current (down right on attached image).
The circuit is three phase, 11 kV ph-ph. The I0-amperemeter is the only amperemeter present in the real circuit, but is only used for protection of the bank. (Disconnect if I0 > xxA) The other amperemeters are added for simulation only.

In a balanced capacitor bank, the I0-current is zero, but I would like to calculate the current based on measurements of the capacitors.

Simulations gave I0=0.2467 A for the conditions shown.

How can I calculate the I0-current, when knowing the voltages (11 kV), and the value of the 6 capacitors?


texts: How to calculate the maximum amplification of a transimpedance amplifier

texts:
I want to calculate the maximum amplification that I can get out of my transimpedance amplifier and I'm struggling a little bit with how to do determine this value.

Is the amplification simply the value of the feedback resistor? Because that is what they are doing in this Texas Instruments tutorial: Transimpedance Amplifiers - What Op Amp Bandwidth do I Need?
In the design example beginning at page 4 they choose a 1 Meg resistor and say that the amplifier has a gain of 1 Meg and a I/V bandwidth of more than 100 kHz.
But when I check the datasheat of the used OPA316 on page 11 the Open Loop gain at 100 kHz is only 40 dB - and if I am not mistaken we would need 120 dB for an amplification of 1 Million.

Is my assumption wrong? Do I mix up something here? Can the I/V amplification be higher than the Open Loop Gain?


texts: Human touch pins on MCU (atmega328p) directly or other components needed?

texts:
I would use atmega328p to read the pulses transferred in human's body. So I wonder if that's good to directly expose the pins of the chip. Or there should be some type of components for protection and noise filtering.

e.g.
maybe a 1n ceramic cap in series for filtering 50Hz house main noise?
a 1K resistor in series for static protection?

Thank you!


texts: how to initialize a vector of registers in verilog?

texts:
I want to initialize the following 16-bit registers in my module.

reg [15:0] coefficient[4:0];

I used concatenation operator to do this:

reg [15:0] coefficient[4:0] = {16'd26, 16'd270, 16'd734, 16'd21, 16'd90};

but I simulate it with ISE, I receive this error:

constant value of constant expression must be used for initialization

how can I fix it??

EDIT: because initial is not synthesizable, I didn't use that. is there another way??


texts: We are using 12V DC solar power at home, and I want to use it for home appliances. Can you suggest what should I have to use for this? At present we are using 4 (12V) lights and one DC fan. Now we want to use this source for AC fans also.


texts: What is the difference between characteristic impedance and input impedance in transmission lines? When are these quantities are equal?


texts: PCB design: vcc plane and via limitations

texts:
I'm newbie in PCB design and I'm trying to achieve my first 4 layer pcb.

Inner layers are gnd and vcc planes filled entirely with copper. My default trace/spacing is 0.1mm/0.1mm and drill size is 0.2mm.

I calculate that a via depending on that specs is limited to 0.5mA. Maybe I'm wrong. But if so, to transfer 2A from front layer to inner vcc plane, do I need to place at least 4 vias in front trace ?

What is the minimum clearance between this vcc via and inner ground plane ?

Thanks in advance for your help.


texts: What's the purpose of the resistor in a 3A load box

texts: There is a resistor R5 in the 3A load box below. It seems it add some positive feedback to Q1, but I'm not sure. What's the exact reason to add it? The circuit comes from here.


texts: Wire laptop power switch to another switch

texts:
A little background to my question: I got a laptop some time ago from my grandparents because the screen was broken and they didn't want to fix it. Being your typical tech geek, I already have a laptop and a more powerful desktop, so I decided to take the motherboard, hard drive, etc. out of the laptop and make it into a small media box to hook into a TV. Wanting to give the front a nice, clean look, I got an LED-lit N.O. momentary switch for the front to switch the power on/off, and I was hoping to wire it in parallel with the laptop's current power switch, taking it out of the loop so to speak.

I'm now looking at the power switch used in the laptop, and I'm not sure where, or if, I can hook wires to it. Here are some pictures:
Top side, switch located lower left.
Bottom side, switch located lower right.

I was wondering if anyone was familiar with this type of switch or had suggestions for testing where the actual switching contacts are? I've taken a multimeter with a resistance test to various pairs of contacts and couldn't find any difference when the button was pressed.

I'm also open to other suggestions for controlling the power from the switch in the front of my new box.


texts: Warning!! Latch has unsafe behavior (vhdl)

texts:
will the warning affect the output result??? Why is this warning happen?
This is my code

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity ASM is
port(clk, rst: in std_logic;
    I   :in std_logic;
    Z1: out std_logic;
    Z2: out std_logic);
end ASM;

architecture behave of ASM is

type t_state is(T0,T1,T2,T3,T4,T5,T6);
signal next_state:t_state;
signal current_state:t_state:=T0;
signal out1: std_logic;

begin
clock:process(clk,rst,I)
begin
    if(rst='1')then
        current_state<=T0;
    elsif(clk'event and clk='1') then
        current_state<=next_state;
    end if;
end process;

next_state_decoder:process(current_state,I)
begin
case current_state is
    when T0=> if (I='0')then
                    next_state<=T1;
                    out1<='1';
                else
                    next_state<=T0;
                end if;

    when T1=> if (I='1') then
                    next_state<=T2;
                end if;

    when T2=> if(I='0')then
                    out1<='0';
                    next_state<=T3;
                else
                    next_state<=T0;
                end if;

    when T3=> if(I='0')then
                    out1<='0';
                    next_state<=T4;
                else
                    next_state<=T0;
                end if;

    when T4=> if(I='0')then
                    out1<='0';
                    next_state<=T5;
                else
                    next_state<=T0;
                end if;

    when T5=> if(I='0')then
                    out1<='0';
                    next_state<=T6;
                else
                    next_state<=T0;
                end if;

    when T6=> if(I='0')then
                    out1<='0';
                    next_state<=T0;
                end if;

    when others=>NULL;
 end case;
end process;

Z1<=out1;
Z2<=I;
end behave;


texts: Lithium ion pack showing 0V after BMS/protection circuit but pack is actually 40V

texts:
I recently purchased an electric skateboard and I ended up having some issues with the board turning off as soon as it started to move.
I figured that there was an issue with the lithium ion pack so I removed it from the board so that I could test the pack with my multi-meter.
It is made up of 20 18650 3.7V 2000mAh lithium ion cells in as 10S2P configuration.
When I read the voltage of the pack at the XT60 connector it starts at about 8V and drops to 0V fairly quickly.
When I plug in the pack to the charger and measure the voltage at the XT60 connector it reads a constant 38.4V
But if I measure the voltage between all of the cells before the custom PCB that has the BMS and the lithium ion protection circuit it reads 40.4V
This makes me think there is an issue somewhere in the custom PCB and that the cells themselves are ok, but I'm unsure how to proceed to be able to use this pack as a functional electric skateboard battery pack.


texts: What could be the transmission loss per metre of using DC current for a low voltage solar system?

texts:
I think that it shouldn't be much but I wanted to get a ballpark numerical figure.

We've installed a 2kW solar power unit at our home, which is installed on our rooftop. To convert the DC current into AC current, there's an inverter at the Ground floor. We can take the wires to the ground around in two different ways.

The second way is about 6m longer than the first. My question is: will this 6m additional wiring cause a significant loss of final output? Is there a formula that I can use to arrive at a numerical figure?

What is the loss (in terms of final output) per metre of DC wiring, as opposed to AC wiring? I have no idea about what the resistance ratings and other properties of the wire is (if that is important to determine an answer to this question). Is there anyway we could arrive at an approximate figure?


texts: How to tell if an IGBT is latched or broken?

texts:
I recently bought an IXXH80N65B4 high voltage/current IGBT. I had it wired according to the circuit below, which is part of a coil gun.

After successfully firing the gun twice, I used the same IGBT in the below circuit, in preparation for the addition of a microcontroller. The datasheet of the IC can be found here.

After powering up this circuit, the IGBT seemed to latch on. Nothing I could do would make it turn off, even shorting gate and emitter. If I supplied voltage to the gate, it seemed to short gate and emitter. Is this IGBT done for, or is there some way to fix it? Also, what can I do to prevent this from happening in the future?


texts: PIC16F1788 - how can I reliably determine when EUSART byte transmit is complete?

texts:
I have an application where I send semi-duplex messages on an RS485 bus.

My slave devices on this bus are normally in receive-mode, listen for commands, and when they get a command they switch to transmit-mode and transmit a response to the master.

The slaves use the EUSART of a PIC16F1788 microcontroller.

I've noticed that the last byte in this response is sometimes corrupt.

I have a theory that this might be because the last byte of the message is not completely transmitted before the slave disables the driver on the RS485 interface chip I'm using, and thus cutting the last byte short.

My code for waiting until the transmit is done is like this:

while (TRMT==0)
{
}
RS485_DRIVER_ENABLE=0;

RS485_DRIVER_ENABLE is a #define mapped to an output pin connected to the transmit enable on the RS485-chip.

Reading the PIC manual:

http://ww1.microchip.com/downloads/en/DeviceDoc/40001675B.pdf

It says:

"The TRMT bit remains clear until all bits have been shifted out of the TSR register."

However, what I'm really interested in is that all bits actually be transmitted, so the above seems to not be exactly the right guarantee I would like.

Should I add a delay of say 2-3 bits after the TRMT is signalled?

Is there any "best practice" for this sort of thing?


texts: Understanding why voltage and current sources are to be divided by s in the frequency domain

texts:
I have been told that whenever I'm drawing a circuit in the frequency (s) domain, the voltage source is to be replaced by V/s and the current source by I/s.

But what exactly is the reason?

When I'm plotting this circuit (replacing s with rad/s), I get that the voltage across R is decreasing as the frequency increase. intuitively, I would say that the voltage or current source should only have a frequency component at s=0, and 0 everywhere else, instead we have that as s approaches 0, the value of the voltage or current source approaches \$ \infty \$ .

simulate this circuit – Schematic created using CircuitLab


texts: Is scavenging parts from consumer electronics for own commercial products, a good idea?

texts:
I have a product that I'm trying to bring to market. For prototype I pulled a camera PCB from an old webcam. It so happens that because my volume of production is low it is actually three times cheaper to buy brand new webcams and pull the PCB and camera off it.
Could I get into trouble for doing this? I will be doing this for market testing and pre production examples (about 100) and if successful I'll get them manufactured myself.


texts: When measuring the fall time, why should you find it between 90% and 10% of the curve?

texts: While researching the standard method of measuring fall time (and rise time) it seems to be standard to take the start and end points for measurement to be when the curve is at 90% of the maximum and 10%. However, I'm having trouble pinpointing an exact reason as to why this is. Any help would be appreciated!


texts: Does Soldering and Attaching/Using Molex Connectors reduce power draw?

texts:
I was looking to attach a Molex connector to the end of a USB by cutting a male Molex connector with a cable, and soldering the black and red USB wires to the black and red of the Molex cable with the attached male connector.

I was wondering if this would reduce the power draw to my device, for instance: I wanted to attach a peltier device to a USB cable for power, and I know that the peltier device has a red and black wire as does the USB. However, I am trying to avoid soldering the wires of the Peltier and the USB together as I would like to be able to de-attach them. So I wanted to take a molex connector, something like this, cut it in half and solder the male side to peltier wire and the female side to the cut usb wires. But will I lose power?


texts: Charging 72V battery bank from 15VDC source

texts: Using a constant source I have a DC generator that can produce over 15 volts continually. I have a 72 volt battery bank and another 72v-motor that runs off of that battery bank. How can I best connect this generator to charge the 72-v bank? How well will a 12v to 72 DC-to-DC Converter work with providing constant charging to the battery bank. Thank you in advance!


texts: How to reset Altium View Configuration Colors?

texts:
How can I go back to the default System Colors in Altium's View Configuration tab?

I've changed the colors but in 3D mode I want to see the original green pcb.


texts: Mesh Analysis with a Current sources and current direction

texts:
Here is the question provided below:

My first question is how is the current 10 A flowing towards the voltage source???? Shouldn't it be in the opposite direction. I feel like my professor is using an opposite convention which is really irritating b/c in all my ECE courses I have been taught to use plus to minus as the current direction for voltage source. Should I just ignore all his currents direction(since I don't know what convention he is using) and relabel all my circuits?

Second question is if I were to do a mesh analysis on 3 loops going in a clock wise direction should the left most loop with the current source just have an equation where current i going around in a clockwise direction just simply set to 5A?

EDIT: and also if 5 Amps are flowing in to the node between R2 and 5 ohm resistor the equation would become

\$I_{in}=I_{out\:}\$
so ...
\$5\:=\:8\:+\:i_2\$

\$i_2 = -3\$

which would make \$i_2 = -3\$???????? so in that case i_2 would be flowing upward which makes zero sense to me because by looking at the circuit the 5 amps from the current source should split up at the node between R2 and 5 ohm in both down ward direction.

Edit2: but then again I might be just flat out wrong about everything I said. Please help a fellow engineering student out.

Edit3 I will solve this circuit and post my solution for you (if you choose to help meout) to check it out b/c I am still unsure, if my assumptions are correct or wrong. Thanks for all your input.

FINAL EDIT

\$I_{in\:}=\:I_{out}\$

\$5\:=\:8\:+\:i_2\$
\$i_2 = -3\$

\$I_{in\:}=\:I_{out}\$

\$8\:=\:10+ i_3\$
\$i_3 = -2\$

I am going to set a ground at the node right below R1.
Then using intuition, i_3 is going actually in the upward direction since \$i_3\$ sign was found to be negative. So \$5*i_3 = 10 \$. So a 10 volt drop from the ground to the node right of the 50 voltage source.

So the node to the right of the 50 Volt voltage source is supposedly at -10 V. Then you go across left and drop 50 Volts. So the node where \$i_2\$ comes in, it should be at -60V  which means V_1 should equal to -60 V?

But that value does not make sense if you do KCL at the node where i_2 comes in.

Can someone please verify my answers? I will post my hand worked solution on a paper if necessary.

And what exactly is a "negative resistor" is this something that I was supposed to know b/c this term was never brought up during class. I have a hunch that he mislabeled some current direction b/c this homework is just supposed to be a simple review for basic circuitry.


texts: Filtering Options for an RTL-SDR (DSP and Analog routes)

texts:
I have several related questions regarding filtering for an RTL-SDR radio. It's readily swamped by the very, very strong AM and FM radio stations local to me. So much so that your basic passive RC circuits do absolutely nothing to attenuate them.
1. I'm considering implementing some kind of DSP solution for this - passing the antenna's signal into some kind of chip that would completely filter out the AM and FM bands.
The Sampling theorem says I would need to be able to sample at twice the highest frequency the RTL-SDR is capable of receiving in order to be able to perfectly handle the incoming signals.
If I understand that right, since the RTL-SDR has a max frequency of 1.75 GHz, I would need to be able to sample at at least 3.5 GHz.
I don't know of any microcontroller that goes anywhere near that high in clock speed, let alone actual sampling ability. And that's just for ADC, not even considering DAC once the filtering's been done.
Would I have to do this on an FPGA, then?
2. if I wanted to instead implement this with active op-amp filters, something tells me I can't just get something for nothing. There needs to be a gotcha somewhere that would limit it.
I'm thinking this would be the highest speed at which the op-amp could switch at? If it can't switch as fast as the highest input frequency, it'll distort them, right?
3. Would it be possible to perfectly filter out an offending signal in a radio by, say, having a time-identical but 180-degrees-out-of-phase duplicate of the incoming radio signal, bandpassing the frequencies I don't want in the out-of-phase signal, then combining this signal with the unaltered signal so that the bandpassed unwanted signals destructively interfere with the same signals in the final output?


texts: Led must be mounted SINK or SOURCE so as not to interfere with communications?

texts:
I used 3.3v microcontroller. I want to add TX LED and RX LED communication on RS232, RS485,
TTL/CMOS.

My question:

Led communication must be mounted as SINKING or SOURCING on I/O microcontroller for avoid interfere in communications?

Picture in here: Datasheet


texts: Choosing resistor values for inverting amplifier and why?

texts:
The gain here is A = -Rf/Rin. However, lets say I want a gain of 10 V/V. Which resistor value would you choose and why?

I know that you could have infinite number of combinations for these resistors but why would some one use specific value. i.e Rf = 100Mohm, Rin = 10Mohm gives a gain of 10V/V but also Rf = 10 ohm and Rin = 1 ohm gives the gain of 10V/V. What difference would it make to the design?

My thoughts say that higher value resistors are not precise so it wouldn't give you precise gain and using lower value resistors sink higher current from the source (Vin). Are there any other reasons? Also, let me know If I am right or wrong as well.


texts:
I need to protect my ADC from overvoltage and over current.
With all the filter elements excluded, the basic configuration i want to build is below(The ADC side will be floating)

On the datasheet, it states that the absolute maximum rating on the ADC pin is (-0.3V ~ VDD+0.3V).

At first, i thought that I could use simple TVS 400W diode with 5V rating. However, looking at the diode's datasheet, 5V rating is for VRWM(working peak reverse voltage) and the break down voltage is about 20 percent greater.

Will ADC port be safe from voltage if i use 5V rated part?


texts: SR Latch settles on equilibrium state with lower voltage supply

texts:
I need to use SR latch for my design and it was working fine. Until I started it with lower voltages.

CON8 and O4 are the inputs. CON9 is the output.

When I use 15V supply, it works very fine:

But when I lower the supply to 9V, I get this:

it settles on a middle point. SR Latch circuit is standard as below, nothing fancy:

why does this happen?

This is the zoom in of the signals:

Output and input rises with the other input falling. Why this is happening? And why this is happening in lower supply voltages but not higher ones?


texts: Power strip with individual time delays for each socket

texts:
I am to purchase a power strip that has programmable time delays for each socket. What I would like to happen is once the power strip receives power, the first socket from the strip counts down from 2 minutes. Once it reaches zero, the socket turns on and power is sent to the connected device. The same process then occurs for the second socket on the power strip where this time I would like it to turn on 4 minutes after it receives power.
Once the timers have counted down to zero I would like them to supply power to the sockets and connected devices continuously. The timers should only restart if the power supplying the power strip is turned off and on again.
I need this type of programmable power strip for a remote device that experiences frequent power surges. Each time the power is cut out from the device I need it to reestablish internet connection before the other components turn on.


texts: I have some X24C44 NOVRAM ICs on circuit boards which I wish to read data from. These devices were used as an identification for each board, for example board 1 contains ID "BOARD1ID001". Is it possible to obtain the identification stored in each RAM if I don't know what pattern was used to store the data? How can I interpret the binary data?


texts: Reduce heat dissipation in Stepper motor

texts:
I'm trying to control stepper motor(NEMA 23/3A per phase) datasheet

I'm using Leadshine M542 Microstepper Driver datasheet

Its controlled by an Arduino UNO with simple potentiometer that can control the speed of the motor.

After starting the motor motor dissipate more heat(about 60 degree of Celsius) than usual.What is the solution for reduce heat dissipation of the motor?

Arduino code

#define DIR 8
#define STP 9
#define POT A0

unsigned int val;

void setup() {
  //Serial.begin(9600);
  pinMode(DIR, OUTPUT);
  pinMode(STP, OUTPUT);

  digitalWrite(DIR, HIGH);

}

void loop() {
    val = map(analogRead(POT), 0, 1023, 150, 1500);
    //Serial.println(val);
    digitalWrite(STP, HIGH);
    delayMicroseconds(val);
    digitalWrite(STP, LOW);
    delayMicroseconds(10  0);

}


texts: Op-Amp decreasing amplitude of audio signal

texts:
For a final project for an electrical engineering course I am taking (my first), we have been tasked with combining input from a small microphone and an aux cord, amplifying it, transmitting it via a laser, receiving it 50 feet away using a solar cell, and playing the same input on a speaker, all powered by a 9V battery.

We were told the laser should operate between 4-5V, the microphone would output at most 10 mV and the aux cord would output at most 0.5V. We were also told to use a bias T to mix the audio signal with a DC signal to power the laser. The transmitting circuit my partner and I designed is as follows:

The circuit works perfectly in the simulation, but not in real life. I first tried to set up the aux input, and at the output of the op amp (U4), the signal is extremely noisy, and quieter than it is at the input (I tested this using the speaker) when it seems to me it should be louder. At the point after the 1k resistor (R13), nothing can be heard except a faint clicking upon connection.

I suppose my question is then, why does an op amp with a seemingly positive gain actually cause a smaller signal (and why is it noticeably more noisy)?

If I have said anything wrong (and I'm sure I have; I don't understand this very well since we were taught almost nothing about AC circuits), please correct me. Thank you a bunch!


texts: Constraining unconstrained integer in record on use

texts:
VHDL 2008 allows us to have unconstrained records. That is a record containing unconstrained vectors:

type dummy is record
    sample : unsigned;
    int    : integer;
end record;

when the record is used to define a signal one writes

signal s : dummy(sample(2 downto 0));

This procedure is handy if one wants to use records in port maps of entities with generic widths.

I like to use integers in some places since it is more convenient to write sig <= 4 than sig <= to_unsigned(4, sig'LENGTH). However if I do not constrain the integer, this might lead to to large types (wasted bits).

Is there a way to constrain these, post-definition, as well?


texts:
I designed a simple half bridge circuit using popular FET driver IR2101 (switching freq. around 500 Hz, drain current about 250 mA, supply voltage about 12 V):

Of course I have resistive load connected between the VS node and ground, forgot to draw it.

This is a part of a bigger schematic, but the bridge circuit doesn't work as I expected. When the high side FET is on, the voltage drop across it (drain-source voltage) is about 2.1 V. When the low side FET is ON, everything is OK - the Vds voltage of it is around 0 V.

Voltage between LO and GND looks pretty good - a square wave from 0 to 12 V.
Voltage between HO and VS looks exactly like this:

I guess that the problem is caused by improper driving the high side, ie. the bootstrap circuit. The gate voltage drops and the high side FET works in its linear region. What could I do to force it to saturate? Is the 1k G-S resistor a problem? I read that there should be such resistor to prevent FETs from various failure types.


texts:
My question concerns capacity in the power grid.  I am an attorney trying to understand whether excess capacity runs in a power grid to avoid brown outs and how long can the excess capacity exist within the grid before it is dissapated or used?  Also, is power generation produced to keep demand below total generation of power at any given time such that demand could be described as operating at a percentage of capacity in the power grid, say for example 98% of capacity?  Or does power generation always equal demand exactly?  thanks for any insights, I am helping a client recover payments to a municipal electric company for excess electricity he was billed but never used since it dissapated through the meter box due to a faulty lug clip damaged when the meter was installed.  I am basing recovery on the theory of unjust enrichment to the power company for electricity paid for by the customer that in essence was produced at zero marginal cost to the end user because the billed power would have been present within the excess capacity generated as a matter of due course because power companies do not operate exactly to the demand. So I am trying to understand if my theory of recovery is accurate.  My client was billed over $100,000 for excess electricity over a 30 year period.

response to comments and answers
Thx every one for helping me understand my erroneous thinking and ignorance on the matter.  I understand that power is used immediately and no excess is in the line.  Voltage and frequency are also variables in the equation.  Marginal costs also increase in the industry for peak periods.  To clarify, I believe the crushed lug clip must have been on the load side which is why the meter registered it.  One electrician who inspected the crush lug clip said the clip and wire were discolored which meant in all likelihood it was glowing extremely hot which caused it to pull the extra current through the meter.


texts: Why is the efficiency of a half wave rectifier equal to 40.6% and not 50%?

texts:
I'm trying to derive the efficiency of a half-wave rectifier using the definition for efficiency,
$$\eta = \frac{\text{output power}}{\text{input power}}$$
And I also know that
$$P = V_\text{rms} \cdot I_\text{rms}$$
So when I computed these for the output and input, I got V0 / 2 and I0 / 2 for the output, and V0 / sqrt(2) and I0 / sqrt(2) for the input.
Plugging in everything, the efficiency should be 0.5, but every source I look at (like this one) tells me that it's 40.6%. Where am I going wrong?
EDIT:
Here's what I did to get the RMS values. I assumed that the rectifier is connected to an external resistance R.
I_0 is the maximum current of the input, V_0 is I_0 * R
For the input,
$$I_{rms}^2 = \frac{\int_0^{T} I_0^2 \sin^2\left(\frac{2\pi}{T} t\right) \mathrm{d} t}{T} =  \frac{I_0^2 \int_0^{T} 1 - \cos\left(\frac{4\pi}{T} t\right) \mathrm{d} t}{2T} = \frac{I_0^2}{2}$$
$$\implies I_{rms} = \frac{I_0}{\sqrt{2}}$$
$$V_{rms} = \frac{I_0 R}{\sqrt{2}} = \frac{V_0}{\sqrt{2}}$$
For the output,
$$I_{rms}^2 = \frac{\int_0^{\frac{T}{2}} I_0^2 \sin^2\left(\frac{2\pi}{T} t\right) \mathrm{d} t + \int_\frac{T}{2}^T 0 \mathrm{d} t}{T} =  \frac{I_0^2 \int_0^{\frac{T}{2}} 1 - \cos\left(\frac{4\pi}{T} t\right) \mathrm{d} t}{2T} = \frac{I_0^2}{4}$$
$$\implies I_{rms} = \frac{I_0}{2}$$
$$V_{rms} = \frac{I_0 R}{2} = \frac{V_0}{2}$$
This gives the efficiency as
$$\frac{\frac{V_0 I_0}{4}}{\frac{V_0 I_0}{2}} = 0.5$$


texts: Differential filters: high pass, low pass, band pass

texts:
I am looking to use a band pass filter in an EMG circuit design using the differential signals you receive from an op amp (differential/instrumentation). I have been looking for what is the proper way to do filtering and have not found a high-pass or bandpass filter explanation like in the article below yet. I realize there is some nuance to differential vs single pole filters, as talked about in TI's article here, like having the "differential capacitor" be 10 times the value of the "common mode capacitors."

TI article on guidelines for filter design

Please especially note Figure 4:

It is very helpful and shows what I would use for a low pass filter on the two lines, equation 3 calculates the cutoff frequency. I have not seen an equivalent article for the high pass filter and so I thought I would ask here to see if its as simple as I think it is or there are other things to think about.

My main question are

whether or not the high pass filter would be similar to the circuit in Figure 4 except the resistors and capacitors are switched, as they are for single pole; and
whether for a band pass, you would just utilize the HPF and LPF in succession if that is the case.

I'll try to make a schematic later today when I have time if it's not clear and I can find a good tool to use.


texts:
I created a 74LS181 circuit in Logisim based on TI's datasheet.  Notice how the NOT gate for the B0 input has a dot before the triangle:

Here's a screenshot of my circuit:

Notice that my inversion for the B0 - B3 inputs are just plain NOT gates as Logisim doesn't seem to offer a variation of it.  I find the 74LS181 a bit confusing as it can handle both LOW inputs and HIGH to achieve different operations.

I've double checked the netlist, although its possible i've made mistakes.  But the operation above is not right.  F is supposed to = 1001 (decimal 9) as the function is: F = A MINUS 1.  The input of A is 1010 (decimal 10).  I am running in arithmetic mode as M = 0.  The status flags S0 - S3 = 0 which is the circuits first function.  Also the carry-in Cn is 0.  The odd thing, is if Cn is 1, then the output is 1010 (10 decimal) which would be correct as it would equate to F = A MINUS 1 + 1.

I'm wondering if the NOT gate is affecting this, or if I have an error in my netlist.


texts: How to clear lcd with a push button in atmega32

texts:
i write this code for atmega32 in which PORTD is out put to the LCD and PIN0 of PORTA is an input which i want to active with a push button.This is my code(main):

void main(void)
{
    PORTA=0x00;
    DDRA=0xFE;
    PORTD=0x00;
    DDRD=0x00;
lcd_init();
lcd_clear();
lcd_goto(0,0);
lcd_puts("Emad Helmi") ;
if(PORTA.0 == 0)
{
    lcd_clear() ;
}
}

i have defined the functions above before my main.but with this code,in Proteus whenever i push the button, nothing happend and the lcd didnt clear!
How can i do this?


texts: Demultiplexing analog fast signal for 2-axis piezo movement

texts:
I am driving a 2-axis stick-slip piezo stage. Currently, I have two controllers, one for each axis. However, I would like to know how can I reduce it to a single controller? I need a sort of a demultiplexer that would allow to pass-through the voltage to either axis (I don't need to move both axes at the same time).

The controller generates a specific signal to move the piezo with max ~50V.  I am using 3.3V electronics (Arduino Due), and have access to a 12V source. I've quickly checked for multiplexers/demultiplexers, but couldn't find one that works up to 50V while is driven by 3.3V (the standard digital output from the Due).

I am considering relays, just have to find out which ones I can drive with 3.3V. Perhaps there's a solution with a triac?

Update: The controller is the OEM version of this one, which is not just an amplifier, but it actually generates a special waveform (the piezo is a stick-slip, and thus requires a certain profile to move the steps). It is not particularly big (i.e. around 3x5cm) but it does get expensive if you need to buy 3 to drive a 3-axis piezo stage.

The voltage does not drop below 0V. Sadly, I have no plot of it, but it basically increases rapidly from 0 to 50V and drops back to 0V for forward movement, and does the opposite for backwards, i.e. increases slowly to 50V, and then drops quickly to 0V, etc.


texts: I have a PCB with the STM32F103CBT7 microprocessor. I used the ST-Link V2 with the STM32CubeProgrammer to programm it which I think worked the first time as it connected and and ended programming without any errors. However, after that I realised the board didn't work as intended and when trying to change the code I got the error dev_target_held_under_reset. I have tried many things since but nothing has worked so I would really appreciate any help


texts: Dummy battery Solution - battery counter

texts:
I'm currently working on a project that will (hopefully) incentive people to stop using disposable batteries.
To do that I'm thinking on creating a dummy battery that will allow you to plug a powerbank with the right voltage and, therefore, powering the device.

I want it to be as dummy proof as possible (no pun intended)

The problem lies on the correct power supply versus the number of batteries in a circuit.

For example, a 4x AA device requires 6V.

I'm trying to find a way of limiting people from plugging a 9V power supply on that case...
Or even getting the battery to correct the voltage automatically in a easy way.
Is there a simple circuit that would allow me to "sense", in a more or less passive way, how many batteries there are in the circuit?

Do you have any idea on how I could acomplish that?

Thank you

To clarify, Imagine the picture below. I want the smart battery to "sense" how many dummies are attached to it. This is a 4xAA example but it could be a 2x or even 6x batteries. (Diodes are just an attempt to prevent reverse polarity)


texts: How to get static on CRT screen instead of black screen?

texts: The TV in question is a Sony Trinitron KV-14M1D CRT. I know it sounds backwards but I need the screen to show white noise for a project (oscillograph); but there seems to be a static block that displays a black screen when static is present. Do you think there could be a workaround by plugging something into the antenna input to trick the TV or something like that? I don’t have the schematics unfortunately.


texts: Confused how to derive output voltage from Op Amp and RC circuit

texts:
So I'm trying to solve the following question:

I'm very confused how they derived the equation for the output voltage. It was from my understanding that for an ideal op amp, the current through the positive terminal (because it's non-inverting) is \$0\$. Therefore, the current through the resistor \$R1\$ should be the same current through the capacitor. So how does any current flow through the 1k ohm resistor or \$R2\$? Because if any current did flow, wouldn't that violate KCL for the node on the bottom to which the source voltage, the capacitor, ground, and the 1k ohm resistor are connected to?


texts: STM DMA won't continuously transmit on UART line

texts:
I am using an STM32L4R5 board and am trying to configure the DMA on the UART2 line. I have managed to get the RX line to operate how I want, but when I follow "Transmission Using DMA" in section 44.5.19 of the "RM0432 Reference Manual" only one byte is transmitted and nothing else.
This byte only gets sent when I explicitly write a byte to the TDR register. Afterwards, I can see the TC flag is cleared and the first byte of my DMA register is affected. How do I get the DMA to continously send out the data to the TDR for transmission?

Note: this problem seems to be simliar to an unanswered question here

The steps mentioned in the datasheet are as shown:

Write the USART_TDR register address in the DMA control register to configure it as the destination of the transfer. The data is moved to this address from memory after each TXE (or TXFNF if FIFO mode is enabled) event.
Write the memory address in the DMA control register to configure it as the source of the transfer. The data is loaded into the USART_TDR register from this memory area after each TXE (or TXFNF if FIFO mode is enabled) event.
Configure the total number of bytes to be transferred to the DMA control register.
Configure the channel priority in the DMA register
Configure DMA interrupt generation after half/ full transfer as required by the application.
Clear the TC flag in the USART_ISR register by setting the TCCF bit in the USART_ICR register.
Activate the channel in the DMA register.

My code is here:

    //filling in dummy info into my DMA TX buffer
    memset((void*)DMA_USB_TXbuf, 0x55, 16);

    //ensuring my UART is configured for DMA Transfer
    huart2.Instance->CR3 |= USART_CR3_DMAT;

    //steps 1-4 taken care of within this funciton
    HAL_DMA_Start_IT(&hdma_usart2_tx, (uint32_t)&huart2.Instance->TDR, (uint32_t)&DMA_USB_TXbuf[0], DMA_USB_TX_SIZE);

    //step 5 (just ensuring that we have the flags we want after the previous function)
    __HAL_DMA_DISABLE(&hdma_usart2_tx);
    __HAL_DMA_ENABLE_IT(&hdma_usart2_tx, DMA_IT_HT);
    __HAL_DMA_ENABLE_IT(&hdma_usart2_tx, DMA_IT_TC);

    //step 6
    __HAL_UART_CLEAR_FLAG(&huart2, UART_CLEAR_TCF);

    //step 7
    __HAL_DMA_ENABLE(&hdma_usart2_tx);

    //I shouldn't need to do this, but this seems to be the only way
    // I get even 1 trasmission from DMA register
    WRITE_REG(huart2.Instance->TDR, 0x55);


texts: calculating power costs on a 45 and 15 KVA dry type distribution transformers due to no load losses

texts:
I would appreciate if someone with expertise could confirm or correct my calculations.

45 KVA 600/120/208 volt dry type distribution transformer
97.7% efficient (therefore losses are 2.3%)
.023x45 = 1.035 KW loss
1.035 KW x 24 hr x 30 days x $.20 kwhr = $149.04 per month

15 KVA 600/120/208 volt dry type distribution transformer
97% efficient (therefore losses are 3%)
.03x15 = .45 KW loss
.45 KW x 24 hr x 30 days x $.20 kwhr = $64.80 per month


texts: What is the meaning of Output data rate of Bosch BMI270?

texts:
what is the meaning of ODR (output data rate)

BMI270 says it has 1.6kHz for accelerometer ODR

does it mean internal registers update rate is 1.6kHz

or

1.6kHz/(16bit x 3) = 33Hz ? (here 3 is, 3 axis)

or

1.6KHz/ (16bit) = 100Hz? (per each 16bit register)


texts: STM32F4DISCOVERY high power consumption in Standby mode

texts:
I wrote an application for the STM32F4DISCOVERY development board (part number MB997C) which places the MCU into standby mode, and measured its power consumption through the JP1/Idd jumper using a Keysight U1252B DMM.

I was expecting a low µA figure (since the data sheet claims a typical figure of 1.7 to 4 µA) and was surprised to get a reading of 285 µA. ST points out that the BOOT0 pull-up resistor uses up 500 µA (although, from looking at the circuit, this should be closer to 300 µA), but I had already taken out that resistor, so this isn’t the issue.

While the board is powered up by the mini-USB connector that connects to the onboard ST-Link, these measurements were taken without the debugger running — the computer should be used merely as a power supply in this situation. When actually connecting the debugger, the figures are higher. I also tried connecting the mini-USB cable to a USB charger rather than a computer, with no change. Next I tried to take out the jumpers that connect the onboard ST-Link to the MCU, and again, saw no change.

Looks like I’m not alone in this finding: these measurements, performed with a Keysight 34461A DMM, show exactly the same current consumption for the same board (see the fourth figure from the top).

I reviewed the schematics and can’t find any other sources for this current leakage from the VDD rail (obviously there are other circuits on the board, but they’re connected to the 3V rail, and the JP1/Idd jumper only measures the VDD rail).

Can anyone help explain what could be contributing to a drain of ~100x the expected current?


texts: Need to isolate panel meters from each other?

texts:
I have a computer power supply I am planning to use for electronics work. I was planning to make a box with voltmeter/ammeter panel meters on each output voltage (3.3V, 5V, 12V, -12V). I have read that the panel meter 9V supply needs to be isolated from the circuit which it is measuring. I was planning on using one of these DC-DC isolated converters to supply the panel meters from the 12V output.

The panel meter specs are:

Power supply scope: DC4.5-30V +
Measurement range: 50A, 30V
Operating current:＜20mA

Can I use one isolator for all four panel meter supplies or should they each be isolated independently?


texts: Trying to make a resistance wire heater to fool an air conditioner's thermostat.

texts: I am trying to put together a fermentation chamber using a window air conditioner and a Johnson Controls A14 Temperature controller. The on-board thermostat of the AC unit will not let it run as low of a temperature as I need. I was wondering if it was possible to make a resistance wire heater to tape or shrink tube to the AC temperature sensor to fool it into thinking it is warmer than it actually is allowing the Johnson Controls temperature controller to control it instead? I was thinking of using a low voltage wall wart or something of that nature for the power source. Any advice would be greatly appreciated!  Thanks in advance


texts:
I am trying to understand the exact working of this circuit, I have been told that this circuit provides a duty cycle of 50% from my previous questions, the same which I successfully verified in LTSpice simulation also, but when I built the exact circuit on a breadboard and observed the waveform on a CRO, I got the following which is clearly not 50%.
I have used the exact same value of components except for R4 which is variable. Can someone tell me what the mistake is as to why I am not able to obtain a 50% duty cycle?
My ultimate objective is note down the corresponding frequencies for different values of R4, but I am confused whether to consider the ON time or OFF time for my application since both are different now?
Apologies if the time scale data of the CRO isn't clear.


texts:
I'm doing a project on beaglebone black and I'm interfacing a LM35 temperature sensor (datasheet) to one of the ADC pins of the beaglebone. As per the Beaglebone datasheets the reference voltage of the inbuilt ADC is 1.8V and it has a resolution of 12 bits. I'm using the below formula for the temperature calculation but I'm getting the wrong values.

$$Temperature = \frac{1.8}{4095} \times (ADC\,Reading) \times 100$$

The ADC reading is 315 and room temperature as measured by the thermometer is 31.2 degree celsius and if I apply the above temperature I get reading as 18.3 centigrade which is not correct.

Not sure where I'm going wrong, I followed this blog to do my experiment.


texts: Low value manually resettable adjustable electronic fuse

texts:
I might be asking for too much with this one, but I hope it is out there. I would like a fuse that can be reset, but not automatically.  I need to be able to know that the fuse is blowing and with a thermal fuse it will just start back up after it opens.  I would also like to be able to change the value in case it doesn't open in time or opens too often.  I need something low around .25 amps up to 1.5amps, and this is going to happen often so I don't want to use glass fuses because of the cost.  Has anyone seen anything like this?  Perhaps a circuit?  Or has anyone seen some test gear that has these features that I can use on the motor until I find out exactly where it will safely blow. It needs to be small because of where the motor is mounted.
Thanks very much,
Russ

Added:
 RM

It is a 12VDC motor. At the moment I don't have the circuit diagram available.
 I don't think it matters if the fuse is at the low or high side.

Sometimes the motors stop switch does not work and it cause the motor drive train to jam and grind down some brass gears. When it jams the current goes up from about 10mA to 30 to 40mA and this is why I need some way to stop the motor.

Hopefully there is a fuse or circuit breaker available that will meet this need.


texts: Identifying polarity of capacitor from PCB printing

texts: I took out the old capacitor and didn't remember to check the polarity because I assumed the board would have more standard markings. Is there any way to figure it out with a meter or by the printing?


texts:
Doesn't look like "Synchronous Ethernet" exist over wireless like it does on wired. Is there any technical reason for it not existing?

On wired, Synchronous Ethernet transfers a 125 MHz master clock to the children for synchronization. Is there any reason why we can't do the same thing in a wireless system?

Edit: Completely reworded question because I didn't get any answers.


texts:
I would like to use a shift register to control source-select in a pre-amplfier.
After watching this very nice video on https://www.youtube.com/watch?v=Y4djl3oYqDQ,
I made the same setup on my bread board using a SN74194N shift register and an old telephone wal wart as a 5Volt power source. To test the clock I used a led with a 330Ohm resistor to ground.
The shift register did not behave like in the video. After a lot of effort I reduce the 10k resistors to 1k resistors.Pins 4, 5 and 6 are now connected to ground with a 1k resistor. Pin 3 to Vcc (and a resistor to gnd) This setup is for bootstrapping the circuit with bit one to high.  To make the shifting go in a loop I connected pin 15 to pin 7 and pin 12 to pin 2. Pin 9 and 10 are connected to push buttons.
After power on and setting the register by pushing both buttons one led is lighting up and I can shift the bit left and right by keeping one or the other buttons pushed in.
There is some strange behavior though that I do not understand

Why do I need 1k i.s.o. 10k resistors?
The chip boots up with random bit turned on. This can be overcome by making S0 and S1 high at start up, but is a bit annoying none the less.
This is really a problem: If I push one of the buttons rapidly, it does not shift the bit, but makes random bits go high. This is really unwanted, because it make more than one bit (input source) selected.

Can you help me understand what's going on and tell me how to solve the third issue?


texts: Question about purely resistive incandescent lamps put in series and fed double normal voltage

texts:
I am curious about how and why if you take 2 purely resistive incandescent lamps (light bulbs) that are rated at 40 watts and 60 watts, both 120V AC (RMS) ratings, if you put them in series and feed them 240V AC (RMS), what will happen to those 2 lamps?  I heard somewhere that the 40 watt light will actually glow brighter than then 60 watt light and I would like to understand why.

I have a 110V to 220V voltage converter so I can actually test this.

I believe if I use 2 same wattage lamps (such as 60W and 60W) and double the input voltage from 120V to 240V, the 2 lamps should burn normal brightness.  "Strange" things start to happen when they are different rated wattages.  Also I wonder if they are grossly different rated wattages such as 25W and 60W, what might happen.

You can assume that the wires connecting all of these are of negligible resistance.


texts: I have an led light strip that requires DC12V, but I want to power it from a wall socket in my home. I have an old battery charger for a laptop that has an output of 12VDC.Would this work safely?


texts:
I have a question regarding stepper motor control while using the TCP/IP stack.

In the past I have used a timer for my stepper motor control. I set the period of a timer to the required time between pulses and then I change the motor phase outputs as needed in the timer tick ISR.  In the cases where I have done this my stepper was moving at a maximum rate of around 400 pulses per second which means the interrupt was occurring every 2.5 milliseconds. And I was using USB for communication to the host.

I am now working on a new product which will use the TCP/IP stack to communicate with a PC over Ethernet. It will also be communicating with other devices via SPI and UART modules. This new device must be capable of operating a stepper up to 2000 pulses per second which means the interrupt may be firing every .5 milliseconds if I use the same timer/ISR approach to drive the stepper. The stepper is turned on and off based on commands received from the host, so communication with the host and operation of the motor need to occur harmoniously and simultaneously.  If the stepper speed varies slightly that would not be a problem but it is not ideal. Also, if the stepper were to pause for say a 30ms in the middle of it's move that WOULD not be acceptable.

I am considering using a PIC24F with the instruction clock speed of 16MHz (32Mhz/2 using the internal FRC+PLL) for this project. Do you think that the interrupts for the stepper will disrupt the Ethernet communication or vise-versa? Is there a better way of doing this?

I have considered using a separate PIC for the stepper control and then I could send that pic target position commands or halt commands to start and stop the movement but that would add another firmware into the mix and complicate things all around.


texts: Does Rload play a huge role in a half wave rectifier?, why when I change the value of Rl the output of the half-wave rectifier graph changes?


texts: What are the problems with LiFePo4 float charging? How should I charge them?

texts:
I can't find any reliable info on float charging LiFePo4 cells. It's quite clear that it's not possible to float charge Li-ion and Lipo cells, but LiFePo4 looks like quite different technology.

I'm interested in building a simple charger using a constant voltage with a very limited current (0.1C). I don't care about a charging speed and a maximal capacity, but I want to maximize a battery lifetime.

I looked into few datasheets but they deal only with classic CC/CV charging. I can't find any info about float charging. Is it OK to charge LiFePo4 with constant voltage (3.5V? 0.1C)? Is it necessary to remove voltage when charging is finished?


texts:
I am thinking of buying a proportional solenoid (PVQ31) valve for a project. I thought of using Arduino to drive this valve but the issue is - this valve needs a range of current supply (0-165mA for 24V or 0 - 330 mA for 12V) for flow control.
How can I have current control using Arduino?
I thought of using digital pots but they operate at 5V only.

Please suggest a solution.

Thanks.

Z


texts: Help on understanding how a strange RTD reading circuit works

texts:
I'm trying to figure out how this universal micro-plc works:
https://www.maximintegrated.com/en/design/reference-design-center/system-board/6185.html

It is supposed to read current, voltage, thermocouple's and RTDs.

And the connection guide:

I'm planning on removing the circiutry that reads voltage and current and retain the thermocouple and RTD circuits. This can be easily achieved by removing the two MAX14763 analogue switches and directly connecting input pins 2 and 3 to the amplifiers. Current limiter section and current sensing resistor need to be removed too.

Apparently the circuit is using some form of the constant voltage procedure for RTD reading, However I have no idea what to do with the two MAX14579 analogue switches because I don't understand how they are used for reading the RTD sensor and why 4 RTD reference resistors have been used. I have never seen a circuit that uses this methodology. If someone knows what is going on here or can point me to a website that explains this procedure I would be grateful.

Edit: schematic:


texts: Why the input capacitance value decrease as the input voltage increases?

texts:
Following is the screenshot of the logic CMOS-inverter curve (Input capacitance vs voltage).
Why the input capacitance decreases with the increase of input voltage?


texts: How do I stop/compensate for a voltage drop across a transistor?

texts: I have used a 555 timer to output a pulsed signal with amplitude 4.6V. I am then inputting this signal into a transistor to pulse an led. When I do this the amplitude drops to 0.8V. How can I stop this large decrease in amplitude?? Any help greatly appreciated!


texts: What type of small diameter motor/generator is best for for a hand-crank cell phone charger

texts:
Currently, I'm designing a hand-crank cell phone charger and I found it difficult to chose the right motor that would fit my design.

The thing is that I need a very thin motor (0.6in (16 mm) diameter) but the ones that I have only deliver around 0.02 A and 5 V. I also I have a bigger motor that works perfectly and gives me 0.1 A and 4 V. But it is 1 in (25 mm) diameter so it is way too big.

The motor that I'm looking for can be very long, up to 4in (100 mm), but can't be thicker than 0.6in.

Any advice where if something like that exists? or maybe I need to use some other type of motor?

I am also using a boost converter.

Thanks!


texts: Why am I getting a half-wave rectified output when i am using a full-wave rectifier?

texts:
I have recently gotten back into electronics and have access to a lab with a signal generator and oscilloscope. I have been trying to teach myself how to use this equipment by building small and simple circuits.

Last night I wired a full-bridge rectifier on a breadboard. The diodes I used were EM518 diodes (those were the only ones that I could find in the lab). What I was trying to do was set up Channel 1 for the input (5VAC-RMS @ 60Hz). Then I wanted to set up Channel 2 to show the output ( ??VDC @ 120Hz). Below is a visual of how I set up the probes:

What I ended up with was a half-wave at the input and a half-wave of smaller magnitude at the output.

Why is this happening? Am I connecting the probe grounds the wrong way? After searching for how to properly connect ground leads, I am now more confused than I was before.

How is this done when working with circuits not connected to the mains? (I'll stay away from mains powered circuits till I understand what the hell I am doing).

Thanks!


texts: Keep old reference designators when copying a schematic sheet into Altium

texts:
We have a pair of designs with Altium that are very similar; one board is a cut down version of the other essentially. We want to import schematic sheets into the new, cut down version from the old version and keep the reference designators exactly as they were.
So, we go to the original schematic, CTL-A, CTL-C and then in the new schematic sheet in the new project and do CTL-C. This copies the existing sheet into the the new project and you can see the old reference designators greyed out. I want to keep these greyed out ref designators in the new project as they official designators.
There surely must be a way to do this? I've tried standard annotating but it just won't keep the designators as they are. I'm importing sheet one into sheet one etc, I'm not in any instance changing the sheet number from one project to the other.
Anyone know how to do this please? Altium don't half know how to overcomplicate simple operations!
Many thanks.


texts: How do I find the Truth Table for Mealy State Machine?

texts:
This is a followup to my previous question:
I have this assignment in college:

You are to design a Mealy state diagram for a safety device. Assume that two debounced push-buttons, A and B, are available to enter the combination. An electromechanical interlock guarantees that the buttons cannot be activated simultaneously. The lock should have the following features:
The combination is A-A-B-A-B-A. If this sequence is correctly entered, an output signal is asserted that causes the lock to open.
For any state, three B pulses in a row should guarantee to reset the control to its initial state.
When any out-of-sequence use of the A push-button occurs, an output is asserted that rings a bell to warn that the lock is being tampered with.
Once the lock is open, pressing either A or B will cause the lock to close without signaling an error. Draw a Mealy state diagram for this finite state machine. Indicate what each state represents and what input conditions cause state and output changes. Not everything may have been specified, so write down any assumptions you make.

I have to implement this Mealy machine using D flip-flops and MUX'es.
I have 10 states for my machine:
S0 -> "Input Start" // Nothing happened
S1 -> A
S2 -> AA
S3 -> AAB
S4 -> AABA
S5 -> AABAB
S6 -> AABABA -> this means EXIT
S7 -> B
S8 -> BB
S9 -> A -> "ALARM ON"

*****Machine States

DIFFERENCE: -> My request is if somebody can show me the way to do the Truth Table for this machine please?


texts: As a translator from German to English, I'm looking for how English native speakers refer to this behavior of incremental encoders. The German here uses "4x-Auswertung" or "Vierfachauswertung" which translates literally to "4x evaluation". I understand this to be measuring the edge changes of both channels A and B. There is also "1x and 2x evaluation" (measuring just the rising/falling edges of one channel). I have researched the Internet and have found a mötley crüe of suggestions: X4 mode, X4 decoding, X4 resolution, etc. Is there anyone here who works with these who can tell me the right terminology? Thanks in advance!!


texts: Do DIN rail mount interface relay modules with a "spare" terminal exist?

texts:
I'm currently designing an industrial control panel that I'd like to be as compact as possible, and was looking at interface relays, and was hoping to find a specific feature, but now I'm not sure it exists.
Basically, I'd like a relay module with an extra connection point for the "other" wire to the actuator. ie. the relay will switch the +ve wire, but the module has an extra connection for the 0V wire. This would be bridged to all the other adjacent relay modules with a jumper bar.
The benefits would be:

Fewer terminals - hopefully cheaper and takes up less space
Wires from a given actuator terminate right next to each other - tidier and easier to understand and debug.

Another way of describing what I'm looking for would be to combine these two devices: interface relay module & a sensor/actuator terminal block (ground connection to the rail optional):

Does anyone know if such a thing exists?


texts: Is amplifier power consumption relative to signal gain, or output volume?

texts:
Is the power consumption of an amplifier proportional to the output volume, or the signal strength increase?

In other words, if I turn the amp volume down by half, and then turn the input line level up double (so the output volume stays the same), what happens to the power consumption of the amplifier? How does this change among common amp designs?


texts: 4 wire resisitive touch screen not working

texts:
I am having a problem with making 4 wire resisitive touch screen work. : This is the touchscreen I am using.
I also have 100 Ohm resistors in series with all the pins. If I understood correctly: Y+ \$\rightarrow\$ +5V, X- \$\rightarrow\$ GND, X+ \$\rightarrow\$ Voltmeter. Which should show me diffrent values, depending on where I press on the screen but it shows me 5V no matter where I press it on. I tried out 3 same touchscreens. On one of them, I even tried out every possible combination of +5V, GND, Voltmeter, but always the same result.

Any help is greately appreciated!


texts: Reducing the range of a D flip-flop frequency detector

texts:
I'm designing a frequency tracking circuit and I came up with a circuit that tracks frequencies from Fclk to Fclk/2:

However, it would be very nice if the bandwidth was a bit narrower, from Fclk to Fclk/1.5, for a higher sensitivity (see red line above), is there a way to modify this circuit to achieve that? Or maybe there are other circuits with similar behavior?


texts: Why do inverter of a EV motor need capacitor?

texts:
Why do inverter of a motor need capacitor? More specifically, a Tesla model 3 induction motor case. But in fact, almost all electrical vehicle's motor has film capacitor. Film capacitor is an important part at inverter, IGBT, or SiC mosfet module. But, why does a  inverter of a EV motor needs capacitor?

Is it used to correct power factor? We know for sure that motor coil is inductance. It causes phase lag and power loses. Does the capacitor compensate it?

Also, I googled. Single phase induction motor has a start and a run capacitor. Tesla model 3 is with a 3 phase induction motor. Does it means that it will has 3 run and start capicitor?

Sorry I am new at electrical parts. Please correct me.

Thank you very much!


texts: What's causing bubbles in my transformer oil?

texts:
I've built a 2-stage Cockroft-Walton voltage multiplier with 10nF ceramic capacitors rated at 20kV each and pairs of 12kV diodes attached in series and hooked it up to an NST with a peak output of 10kV. It worked just fine with one small problem-the capacitors began flashing when the input was around 3kV (peak).

So I immersed the multiplier circuit in transformer oil and tested it again. There was a steady arc starting from an input of about 600V all the way till I increased the input to around 5kV peak. At this point, the arc suddenly vanished and I noticed bubbles coming from the ceramic part of my first capacitor (the one connected to the supply).  So I brought the input down to zero, waited for a while and gradually increased it again.

This time,however, the arc wasn't steady and increasing the input only increased the frequency with which it struck. I've since replaced the capacitor, but with the same result as before (bubbles coming off the capacitor underside, followed by a non-steady, Marx-generator style arc).

I noticed there wasn't any physical damage on the capacitors once I took them out of the oil, so I thought the capacitor leads were causing Corona discharge and decomposing the oil. I wrapped the leads of the first capacitor in insulating tape and the bubbles began popping up at the the ground capacitor. I have one last spare capacitor left and I don't want to ruin that one as well. I really want to know what's causing these bubbles and sabotaging my output. Any help would be greatly appreciated. Thanks :)


texts: Joining two AC inputs with different voltages

texts:
I have a project where we have to design a wind turbine. I currently have two 5 kW generators (https://wxftgs.en.alibaba.com/product/60689557542-804881319/5kw_permanent_magnet_generator_price.html?spm=a2700.8304367.prewdfa4cf.2.73152c54UBoPer)
that need to go to a single inverter (https://www.mecerpc.co.za/Mecer-SOL-I-AX-5M-p-123749.php).

I need to join the two AC outputs of the generators to a single input to the inverter. The generators will be producing different voltages due to the different wind speeds.

Is it possible to join the two or should I just have a separate inverters for each turbine and connect the inverters in parallel?


texts: Detailed explanation for PIC boot sequence

texts: I have doubts about the boot sequence of about every microcontroller but since I own a PIC I figure I should start with those first. I would like someone to explain how the PIC's boot sequence progresses. While explaining that I would also like to know how the PIC sets its clock setting such as internal or external clock without first knowing which one to use does it use its internal clock and then sets the clock to external once the register has been set?


texts: How to compute Rth for this circuit using OrCAD PSpice

texts:
Take a look at this circuit

The question asks to find Rth and Vth between a-b terminals. Hand calculation yields Rth=3.857 and Vth=4V. With OrCAD, the result is shown below using Bias Point simulation:

Unequivocally, Vth=19-15=4V which agrees with the hand calculation. The problem is with computing Rth which is computed by changing the simulation to DC Sweep and find the slope between I2 and its voltage. If I do so, OrCAD starts from 19V rather than 4V but subtracting it by 15 to correct it which yields the following

Rth is the slope of the green line so, Rth=(6.429-4)/1=2.429. There is a big large error. Any suggestions.


texts: Arduino IR practice vs. application circuit on 1838 datasheets

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There is an explanation of wiring up IR remote controllers for beginners at arduino-info.wikispaces.com/IR-RemoteControl, which suggests wiring the output pin directly into an Arduino pin.  I've tried this, works fine.

The application circuits given in the datasheets for the VS1838B (Chinese) and AX-1838HS have a capacitor between VCC and GND and 10k or 20k ohm pull-up resistor between VCC and OUT.

If I understand the internal wiring diagram though, these 1838 units already have an internal pull-up resistor between VCC and OUT, so this external resistor merely changes that pull-up.  Why are the capacitor and other component there?  Are they filtering out noise?


texts: Task:Design a"Disinfection Chamber". Solved it using s-r latches. However, since it was not taught, it was not allowed. How to solve this without it?

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Here is my design:

I was asked to design a digital circuit of "Disinfection Chamber" (Below).
I solved it using 2 s-r flip-flop.
But apparently, I can't use flip-flop because it hasn't been taught.
Any idea of how to solve this without flip-flops?

I've already done the k-maps, equations, etc but my lecturer said that I can't use flip-flops or anything Q(n+1) :(

The question:

Si: IN Sensor (active HIGH)

So: OUT Sensor (active LOW)

S_Up: UPper level of water Sensor (active LOW)

S_Lo: Lower level of water Sensor (active LOW)

M1: water pump (active HIGH)

M2: water sprayer (active HIGH)

Conditions:

Water pump (M1) will be ACTIVE when water is below sensor level S_Lo and will be INACTIVE when it reached S_Up.
Water sprayer (M2) will be ACTIVE when :

a. Water container not empty
b. There is somebody entering the room

Water sprayer (M2) will be INACTIVE when:

a.  Water container is empty
b.  A person is coming out from the exit
c.  No one is inside the room


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All current limiting circuits I've found until now use some sort of analog Logic with Op-Amps to limit/control the current.

(Why) is no digital current limiting used?
I would imagine a shunt resistor for measurement and a MOSFET for controlling being a flexible solution, when you already have a MCU in your build.


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I can't understand why L1 has four windings? And how we get -12 V if there are two diodes connected towards each other. How will current  of -12 V flow?
And do thos fours windings work as transformer?


texts: Warming PCB in a low temperature environment

texts: I have to develop a microcontroller circuit that will run at low temperatures (as low as -60C). I want to heat the FR4 PCB board until it reaches the commercial temperature range above -40C. I found some flexi heaters to heat the PCB. What other options do I have? Is it possible to use a PCB layer as heater? I couldn't find any information about using a layer as a heater.


texts: Water level: BIG capacitive level sensor with steel bars?

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So I want to measure water level under a bridge, or inside the city drain.

Would it be possible to run two long (4 meter) metal probes, each one enclosed inside a PVC pipe, and placed one next to the other separated by a few cm, and use that as a capacitive sensor? I know it works on a small scale (two insulated PCB pieces inside a water bottle). But will that work on a bigger scale?

The idea is that the metal probes work as a capacitor, and as water level increases and occupies the space between the two PVC pipes, capacitance should change.

Would it be better to make the probes out of copper foil ? I would prefer 2" x 3/16 steel bars just to make it more rugged, but don't know if that would affect the electronics.

The sensor will be read with an Arduino + http://playground.arduino.cc//Main/CapacitiveSensor?from=Main.CapSense

I also have an ultrasonic sensor, but another application for this would be to put it inside a hole (drain) that sometimes gets flooded (there is a chance that the sensor gets wet).


texts: Why do electromechanical relay computers tend to use higher voltages?

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So I am contemplating building a relay computer. And I have not seen any information on why one would select one voltage over another.

It seems that it would be ideal to use 5V relays as that is slightly easier to interface to microcontrollers (which I would personally want to use for debugging during design/building). As well as being slightly cheaper.

Harry Porter's relay computer runs on 24V and the TIM8 uses mostly 12V relays (some where 6V unbeknownst to the designer at the time). Also "Fist Full of Relays" is 12V.

The main problem I can see as a possiblity would be fanout... I could also see how in that case it might be advantageous to use multiple voltages. For instance a single 5V relay could drive a bunch of 24V relays at 24v.

Another possible problem is sourcing enough 5V power since 5v rails tend to be lower amperage.


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I have an Ethernet peripheral (manual here) controlled by an STM32. I have to test that the Ethernet peripheral works correctly right after the board is manufactured. Conveniently, there are three "loopback" modes for testing. (See page 41: near-end, far and connector loopback.)

I wonder if using these three loopback testing modes (doing basic I/O) is sufficient to guaranty that the Ethernet peripheral will work properly in production.

Are there non-loopback tests that I should consider to test the integrity and functionality of my Ethernet peripheral?


texts: I need help in designing an analog front end for a MOSFET based sensor

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I'm currently designing an analog front end for an ion sensor (ISFET), the purpose of which is to automatically extend the sensing range of the sensor once the analyte concentration reaches the detection limit of the sensor/ return to the normal sensing range of the sensor once the analyte concentration is within the sensor's normal sensing range. Here is a sample circuit of the MOSFET based sensor which can only sense within its default range limit (output is between the capacitor C1 and ground) :

I've already figured out how to extend the sensor's sensing range (by placing a non-inverting amplifier between the source and gate terminals) as shown in the image:

My current roadblock is how to automate the process. For now, I just manually switch between the default and the extended range using the following circuit:

The voltage output for the normal concentration ranges from 0.88-1.0v, while the voltage output for the lower concentration, amplified by the non-inverting amplifier, ranges from 0.465-0.505V. The voltage ranges are specific for a certain type of ion (Cu+2)
I already had two ideas in mind on how to execute this automation: My first idea involves varying the resistance of either the feedback or input resistor of the non-inverting amplifier (changing the gain multiplier to "1" during normal concentrations and "2" during low concentrations), though I currently have no idea how to execute that. My second idea (actually suggested by someone) is to make use of the switching circuit mentioned before and add a couple of comparators and flip flops, but I am also having a hard time on how to execute it.


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So, I was wondering, how to draw or specify Vcc to the output characteristic (Ic versus Uce - common emitter), when we apply positive voltage (+12V lets say) to the collector and negative voltage (-12V) on the emitter terminal.

Should Vcc value (to be used in calculations) be 12V or 24V? When calculating Rc = Ucc/Isat , which of two values should be used?

Is there anything special about this circuit (when we talk about biasing of the transistor with two power supplies - one positive & one negative)? Is base still biased to approximately 0.7V?


texts: What is the effect of external ESD protection on noise?

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I am measuring very small currents/voltages (nA, uV) using a precision op-amp. What effect on noise is likely from external ESD protection (clamping to +/- 15V) on the input signal path?

Circuit below