texts:
Hi I am trying to write a code in VHDL and I get syntax error near "end" / "if". I am not very good at nested if statements and have not figured out how to close those if statements in what order due to lack of internet sources. I am pretty sure that errors I receive are due to if statements, especially due to those which are not properly closed. How can I overcome this problem and continue my project? Here is a code segment I am getting error from. I wrote //ERROR HERE// to denote where an error occurs.

    SHOW : process (clk, rst) is
    begin  -- process SHOW
    if rst = '1' then
    processed_pic <= def_pic;
    cursor_pos_x <= 0;
    cursor_pos_y <= 0;
    elsif clk'event and clk = '1' then
    if (visible = '1') and ( pos_x < 250) and (pos_y <250) and (pos_x > -1)
    and (pos_y > -1) then
    if((pos_y = cursor_pos_y) and ((pos_x > cursor_pos_x -1) or (pos_x <
    cursor_pos_x + height ))) or ((pos_y = cursor_pos_y + height -1) and
    ((pos_x > cursor_pos_x -1) or (pos_x < cursor_pos_x + height))) then
    vgaData <= "00000000000";
            data_r <= vgaData(3*COLOR_BIT-1 downto 2*COLOR_BIT);
            data_g <= vgaData(2*COLOR_BIT-1 downto COLOR_BIT);
            data_b <= vgaData(COLOR_BIT-1 downto 0)

   //ERROR HERE// if ((pos_x = cursor_pos_x) and ((pos_y > cursor_pos_y - 1) or (pos_y <
    cursor_pos_y + height))) or ((pos_x = cursor_pos_x + height -1) and
    ((pos_y > cursor_pos_y - 1) or (pos_y < cursor_pos_y + height))) then
    vgaData <= "00000000000";
            data_r <= vgaData(3*COLOR_BIT-1 downto 2*COLOR_BIT);
            data_g <= vgaData(2*COLOR_BIT-1 downto COLOR_BIT);
            data_b <= vgaData(COLOR_BIT-1 downto 0)
    //ERROR HERE //end if;
    else
            vgaData <= processed_pic(pos_x,pos_y);
            data_r <= vgaData(3*COLOR_BIT-1 downto 2*COLOR_BIT);
            data_g <= vgaData(2*COLOR_BIT-1 downto COLOR_BIT);
            data_b <= vgaData(COLOR_BIT-1 downto 0)
    //ERROR HERE //if ((pos_x > 249) and (pos_y > -1)) or ((pos_y > 249) and ((pos_x > -1)
    or (pos_x < 250))) then
            vgaData <= "000000001111"; -- mavi
            data_r <= vgaData(3*COLOR_BIT-1 downto 2*COLOR_BIT);
            data_g <= vgaData(2*COLOR_BIT-1 downto COLOR_BIT);
            data_b <= vgaData(COLOR_BIT-1 downto 0);
    end if;
    end if;
    end if;
    end process SHOW;


texts:
My graphics card (geForce 8600GT) stopped working, because it has some blown capacitors.

I will try to replace them myself but I have no experience repairing hardware. I'm not sure what capacitors I should buy. The capacitors I need to replace are three "FZ7C 1500 6.3V" and one "FZ7C 1000 6.3V".

Is it ok if I replace them with these?
http://www.dealextreme.com/p/1500uf-6-3v-motherboard-electrolytic-capacitors-20-piece-91615?item=24
http://www.dealextreme.com/p/6-3v-1000uf-aluminum-motherboard-capacitors-20-piece-pack-94455?item=18


texts: Can I prevent a 9V LED flickering when dimmed to around 30%?

texts:
I bought an overly bright 9 volt, 3 watt LED to light up a bird box which has a webcam in it. The LED module is this one: https://www.amazon.co.uk/gp/product/B07CWSRF6N

However when I dim it using a simple 12V dimmer to 50% or less, it starts to make the video feed flicker due to the strobing LED's interaction with the camera frame-rate.  It's being driven by a spare 9V DC power supply previous used for a broadband router.

Can I fit a capacitor across the LED to help smooth it?  If so, what kind of value would I need?  Or am I better just to fit a big load resistor in front and remove the dimmer?

Thanks!

EDIT: Here's a pic of the dimmer innards:


texts: How can I test for a closed circuit without adding excessive resistance?

texts: I have one speaker and two audio inputs. One of the inputs is powered by a 12VDC circuit; I want to switch the speaker to this input only when this 12V circuit is closed. If I add a double-throw relay to that input's circuit in series, I end up with insufficient voltage for both the input and the relay due to the resistance added by the relay's coil. Is there any way I can do this using a relay, or is a manual switch my only option?


texts: Finding the voltage and charge across capacitor

texts: Can someone help me find the voltage and charge across each of the capacitors? This is not just a simple/ parallel circuit so I am having a problem in formulating the right equation on how to find the voltage and charge across each capacitor.This is actually a charge pump wherein capacitors pump charges to the load capacitor, CL.


texts: What is the name of this connector from a fan?

texts:
I am EE hobbyist and I often used recycled parts in my projects. I came across this connector to a Heat Sink Fan and would like to know the name of it.

Thanks for the help.


texts:
I am currently trying to communicate via I2C to HDMI transmitter ADV7511 from Zynq 7000 Soc, I used  this example as a reference for start, but yet without success, program get stuck in function XIicPs_MasterSendPolled() at this lines of code

    /*
     * Check for completion of transfer.
     */
    while ((IntrStatusReg & XIICPS_IXR_COMP_MASK) != XIICPS_IXR_COMP_MASK){

        IntrStatusReg = XIicPs_ReadReg(BaseAddr, XIICPS_ISR_OFFSET);
        /*
         * If there is an error, tell the caller.
         */
        if ((IntrStatusReg & Intrs) != 0U) {
            return (s32)XST_FAILURE;
        }
    }

It never exits from this while loop, what are possible reasons, or advices what to check?

Thanks!


texts: What is the following MOSFET circuit good for?

texts:
Context: I'm studying basic electronics at an undergraduate level.

One of the questions in past exams was to explain the usefulness of the following MOSFET wiring. Judging from the picture I assume that the question refers to the fact that Vo is wired back to the gate of the MOSFET.

I skimmed through my book and the closest thing I could find was under the paragraph "reference voltages and current sources", but it hardly mentioned anything. Would anyone be so kind as to explain things a little bit ? What's so special about the above circuit and what exactly does a reference circuit do ?

I googled "reference circuit" and got the following from Wikipedia:

  "A reference circuit is a hypothetical electric circuit of specified
  equivalent length and configuration, and having a defined transmission
  characteristic or characteristics, used primarily as a reference for
  measuring the performance of other, i.e., real, circuits or as a guide
  for planning and engineering of circuits and networks".

Is this relevant to my case ?

I tried to solve the circuit given \$K=1.5mA/V^2, V_T=2V, R=10KΩ\$. I came up with the following two equations:

\$I_D = K(V_{GS}-V_T)^2=K(V_G-V_S-V_T)^2=K(V_0-V_T)^2\$, since the gate and Vo are short-circuited. The second equation is \$V_o = 20 - I_D R=20-10I_D\$.

Therefore combining the two equations, I get: \$(20-V_o)/10=1.5(V_o-2)^2\$. From this equation I get \$V_0=\{0.87, 3.03\}\$, accepting the \$V_o = 3.03\$ so that \$V_{GS} = V_G = V_o = 3.03 > V_T = 2\$.

A colleague of mine though calculated \$V_o=9V\$. Does anyone see where I'm mistaken ?

Another colleague pointed me at this link [pdf] with a MOSFET diode-connected circuit whose description paragraph sheds some light.


texts: Can I control the flow of a 12V power supply with a 4.5 volt power supply and a IRF3205 mosfet?

texts:
To start I am very much a beginner at electronics and am very limited in my tools.
I bought a IRF3205 mosfet a few days ago hoping that I could use it in a circuit I have where a 12V power supply at 1.5A is capable of going from the source to the drain to turn on an LED light strip. The would be mosfet controlled by 4.5V supplied by three triple a batteries at it's base.
I was disappointed though to test it and see that this mosfet only outputted less than 9v at the drain(I don't have a way of finding its current). Is there a way to make this mosfet work or do I need to buy a new one? If I need a new mosfet can I get a recommendation?
Again my goal is to control an LED strip—running at 12V, 1.5A—with a 4.5v battery supply going on and off with as few parts as possible, preferably just a single mosfet and no resistors or capacitors


texts: In the given circuit, will the resistor have current across it?

texts:
Since the higher potential is connected to ground, how would the circuit behave?
When the ground is removed, it turn out to be a simple circuit. But, upon addition of the ground at point G, the higher potential of the battery gets grounded, so how does this effect the behaviour of the circuit compared to previous condition(absence of ground)?


texts: TEC2-25408 - 8A 12 V - goes max at -20° 4A

texts:
I have tried to power that pelletier module with an AT power supply but I reached max -10°C or something

I ordered a 12V 10A power supply, as I measure the peltier module, it really does not go up to specs.

Barely -20°C (should <-30°C)
and current is only half of the specified current

Peltier:

https://www.aliexpress.com/item/32386272344.html?spm=a2g0s.12269583.0.0.662f6f04RWvMLA

Power supply:

https://www.aliexpress.com/item/32990203636.html?spm=a2g0s.9042311.0.0.3da24c4d7hBp9i

Fan:
I am using a 12V fan with a 10x10x4cm CPU fan

What am I missing ?


texts: What is happening when I am adding a load capacitor in CMOS inverter?

texts:
I want to simulate an inverter with CMOS. When I added a load capacitance and plotted the output voltage. I saw a sharp voltage graph so I have changed the dimensions of the transistors and got the graph that is shown below.

What is happening when I am adding a load capacitance?
Here is the circuit with capacitance.


texts: Understanding Negative feedback loop circuit with an Ideal Op-Amp

texts:
The following is given as an example of a negative feedback loop in my textbook, note that the op-amp is assumed to be ideal.

However I do not seem to understand the logic behind this acting as a negative feedback loop.
Suppose if \$V_{in}\$ is \$0.01V\$ after passing through the op-amp. It should be amplified to \$+6V\$.
Now \$V_{out}\$ is \$+6V\$ hence the inverting input will also become \$+6V\$ thus the difference between the two inputs becomes \$-5.99V\$ thus \$V_{out}= -6V\$ and this process shall repeat over and over again. Would the circuit then just cycle between being \$+6V\$ and \$-6V\$ until the power supply is disconnected?
How is this considered a negative feedback, am I missing something crucial?


texts: Reading power supply value in the datasheet ; -0.3 V to 6 V ? ; Unclear

texts:
I am working on IR module and was referring to datasheet from Vishay. While looking at supply voltage it showed -0.3 to 6 V. I am unable to understand -0.3 V, how -0.3V can power the circuit.
Then I looked at Op-Amp from TI, the datasheet, shows same pattern.
Pl suggest or point me to reference which I can read.
Does it mean 6-0.3 V = 5.8 V max, but then they could have written it.


texts: Small-signal output resistance of MOS common-source stage with source degeneration

texts:
This is a bit of a long question so bear with me.
In chapter 3 of Razavi's Design of Analog CMOS Integrated Circuits, he introduces the CS stage with source degeneration. He draws the small-signal model and says that the output resistance is as follows (Eqn 3.65):

That makes complete sense to me and I am able to derive that via the small-signal model. Next, Razavi provides another technique to derive the same small-signal output resistance without drawing the small-signal model but rather incorporating it with the large-signal drawing as a means to quickly inspect circuits and gain some intuition. To do this, he applies a ΔV and measures ΔI as shown below,

I understand how he has transitioned from Fig 3.30(a) to (b) and to (c). My confusion is regarding the final step where he calculates the output resistance itself,

I can understand what he is doing but what I don't understand is that as soon as he simplifies the circuit to Fig. 3.30(c), we have a circuit that comprises only of resistors.
Why can you not simply at this stage (Fig 3.30(c)) just write that,
$$ R_{out} = r_o + Rs||\frac{1}{g_m + g_{mb}}$$
Why does this not give the same result as Eqn 3.65?


texts: Dependence of mobility of charge carriers in semiconductor on the applied electricfield

texts:
The mobility in a moderately doped semiconductor depends on the temperature, carrier concentration and the applied electric field. so I want to know:

How does mobility vary with electric field while the temperature and carrier concentration are kept constant?? Is there any empirical relation or a model that speaks about it?
Similarly how does the mobility vary with temperature (Apart from the lattice scattering and ionized impurity scattering phenomena)?

Please suggest any books that speak of these aspects in detail.


texts: Driving +5V to a digital pin configured as output on the Atmega32

texts:
I am a little confused about what happens if i supply +5 volts to my digital output pin, Pinx, which is configured output LOW.
is it OK or will I damage Pinx?


texts: Choosing op-amps with voltage output swing

texts: For a 2 kohm load, typical output voltage swing  Op-Amp #1 is 13V, and the minimum is 10V with a 15V power supply. Its maximum supply voltage is 22V. Let's say I have another op-amp (Op-Amp #2) that has a typical output voltage swing for a 2 kohm load as well of 12V and a minimum output swing of 10V with a 15V power supply. Which op-amp do I use if I want an undistorted Vout peak voltage of 12.5V? Any help is appreciated thanks.


texts: Have I burnt my MAX II by excessive soldering?

texts:
I soldered my first TQFP 100 package, an Altera MAX II EPM570 CPLD, on a PCB.
But I only found the "correct" way to solder (put flux on the pads and on the pins, melt some tin on a thin iron tip, then gently move the tip across the pads without touching the pins) on the fourth side, after several tries with the other three.
Blobs were forming on the pins; I tried using solder wick to remove them, but for some reason it didn't absorb absolutely anything. Even with the iron set to 420°C and pressing the tip for 10-20 seconds a few times. Then I read the advice to apply solder flux to the wick, and finally it started doing its job. So I managed to remove all the blobs.
This is how it looks now. East side went flawlessly, the other sides are repaired:

I'm concerned I've burnt the chip due to excessive heat. Here are my questions:

Should I just desolder this chip and try again with another one?
If I decide to keep it, can I verify that all the I/Os are still working before mounting all the other components? I can solder what's necessary to power it up and connect via JTAG. Reason I ask, is that I have a CPLD with a burnt I/O with everything else still functioning otherwise.


texts: Non-inverting version of EL7232? (High-frequencey 3-state DIP driver/buffer)

texts:
I'm driving a large number of parallel UART inputs from a single UART output, at 2 Mbit. Currently, I'm driving with a Atmega32u4 using a 70 Ohm current limiting resistor (which in theory would allow exceeding the specified maximum output current of 40 mA, but in practice doesn't do that for enough time to hurt the device.)

I need this driver to be able to tri-state or disable, because I also read data from the other devices on this TTL-level UART bus.

I am seeing some signal quality issues, though. I'd like to clean up the signal by using a lower-impedance driver -- really, a single channel of buffer with tristate ability and high bandwidth would be great! (I can accept 50 ns rise/fall times into 1000 pF, but no worse than that.)

My first idea was to use a regular half-bridge driver, like the L293E. However, that doesn't have fast enough rise/fall times for this signal.

My second idea was to search DigiKey parametric search. I came up with a number of possible devices, but none of them actually has all of the features I need. Either they are missing a tristate/disable input, or they have too slow rise/fall times. The only device I've found with both fast rise/fall and tri-state/disable inputs is the EL7232. Unfortunately, this device is inverting! I can't find a mention of a non-inverting version of this device in the data sheet, or through applying DigiKey search.

It would seem like there should be a chip that does what I need it to do, but I can't find it. Does this ring a bell for anyone? Am I missing something? Is my best bet to put an inverter (N-channel low-end switch plus pull-up resistor) in front of the EL7232, consuming more precious board space?

Edit: I keep forgetting to add this requirement when I ask questions: I am a dinosaur who does not know how to operate a toaster oven, and also have a large existing stash of through-hole parts I'd like to not have to throw away. I am only interested in through-hole solutions.


texts: Wiring a traffic light as a brake lights

texts: I am trying to wire in a set off traffic lights as my brake lights/turn signals on a rat rod truck. My question is how would I proceed with it? IE, they are a 120v ac design led bulb and would need them to run on a 12v DC setup.


texts: How are various functions (eg. add, subtract, and, etc) implemented in ALU?

texts:
I am wondering since there are so many functions an ALU need to do, how might I start implementing one (a homework where I am supposed to implement a MIPS system with Logisim, using basic Gates, Flip-flops etc).

The part I am confused about is how can I implement an ALU which can do different functions like Add/Subtract/AND/OR/etc. Do I need to more control logic (see top right in "prev assignment" below).

In a previous assignment, I implemented an ALU that can do Add/Subtract/Negate. Now I think an ALU should be able to do functions like

My prev assignment


texts:
I'm very new to digital design (my background is software).  I'm trying to make use of some block RAM on a Xilinx FPGA, and I want to know what the usual methods are for setting up the RAM control signals w.r.t. the clock.

I currently have a single clock used by all of my design.  The RAM can perform a read/write every rising edge, and I want to use it at that rate.  Of course, the control signals need to be set some time before the rising edge of the clock.  I imagine there are a few ways to do this:

Set the signals on the falling edge of the clock.
Set the signals on the rising edge.  The synthesis tool is clever enough to know what I want, knows the required setup time, and takes care of everything.
Set the signals on the rising edge.  The synthesis tool isn't clever enough, but I can do funny things with timing constraints to get the signals set up early enough.
Use two clocks slightly out of phase, set the signals on the rising edge of the leading clock.
Some other approaches?

Which of these are possible, which are actually good or usually used, and are there any advantages or disadvantages to help choose between them?

Edit: I'm using plain VHDL for reasons of portability, and not using Xilinx-specific CoreGen or primitives.  I'm following Xilinx documenation though, and writing the VHDL in such a way as to let the tools infer the correct RAM type ("RAM HDL Coding Guidelines in UG687 if anyone is interested).  The tools seem to be doing this correctly.


texts: Can I use ICSP if components share MOSI/SCK pins?

texts:
I'm designing a circuit with an ATmega32U4 where I will need to burn a boot loader once installed on the PCB. I currently have 4x 74HC595 Shift registers, sharing the MOSI & SCK pins.

Will I still be able to plug the programmer in and burn the boot loader via ICSP with no issues?

MCU

Shift Registers

ICSP Header


texts:
I want to feed SIM800L a microphone signal.
I found this page in the datasheet and it worked but I need more a sensitive microphone. I want to hear voices in room as much as possible, like a spy bug.
The SIM800L microphone input is designed for millivolt level signaly so I have problem with amplifier audio in.
How can I solve this?


texts:
I just solved a problem in my homework. I had to calculate the reflection waves and I was given the following data:

Resistance
R0 = 120 Ω line impedance
Ri =  90 Ω resistance at input
Rb =   1 kΩ termination resistance

Line
l = 0.5m length of the line
δ = 6 ns/m

Source voltage
U0 = 0.4 V logical 0 - low voltage
U1 = 4.8 V logical 1 - high voltage

I was also given the following graph:

Showing I have to calculate reflections for when signal goes from 0>1 / low to high voltage basically when we have a pulse.

First I  calculated Tau, T = l * δ = 3 ns, and then I calculated the reflection coefficients at R0 and Rb using formula ρx = \$ \frac{Rx - R0}{Rx = R0} \$

With that I was able to calculate for the part before the pulse:

  ui(0-) = ub(T-) =
  U0 \$ \cdot \$ \$ \frac{Rb}{Rb + Ri} \$

Followed by the rise:

  ui(0+) = ui(0-) + ΔU \$
 \cdot \$ \$ \frac{R0}{R0 + Ri} \$

And then I was simply able to calculate reflection voltages at certain time for instance first traveling voltage from the change:

  u0(1) = ΔU \$ \cdot \$ \$ \frac{R0}{R0 + Ri} \$

And then reflection voltage at T on the end of the line:

  ub(T+) = ub(T-) +
  u0(1) + u0(2)

After that I can just calculate the reflections until 5 Tau to see if the signal stabilizes anyhow.

My question is how do my calculations and formulas change when the graph provided would be inverse showing a drop in the pulse from 4.8V to 0.4V ?


texts: Simplest way to produce a lagging pulse (latch trigger) after receiving another pulse (clock trigger)?

texts:
I am teaching myself how to use a 74HC595 shift register, and am fairly new to proper digital circuit design.  I ran into a question.  I am using a simple circuit involving a few LEDs, a switch for data, and a couple of pushbuttons to pulse the register clock and the latch clock.  Basically, I can clock in the data, but it won't update the output LEDs until I pulse the latch clock.

I would like to get rid of the latch pushbutton and have it automatically latch pulse after each clock pulse high trigger.  I am wondering what the easiest way is to "echo" a pulse from one clock to the next using simple parts?  I.e., when I send a Low-to-high on the clock pin, I want another low-to-high-to-low to immediately follow on the latch signal.  The latch signal just needs to stay high long enough for the register to recognize it, not necessarily for the same duration as the original pulse.  Half a microsecond should be sufficient for the delay and the duration of the following pulse.

It is not simple enough to tie the clock and latch to the same signal.  This results in the display always being one pulse behind (as described in the data sheet).

___/-\_________/----\________ Leader clock
____/-\_________/-\__________ Follower latch
... or perhaps some sort of delay line...
___/-\_________/----\________ Leader clock
____/-\_________/----\_______ Follower latch

Could I clone the clock pin to the latch using some sort of MOSFET with a capacitor for delay?


texts: Ethernet 100 ohm differential pair layout

texts:
I'm finishing off the layout of a board in Eagle which has a LAN8710A 100Mbps Ethernet PHY on it. The SMSC documentation is really pretty good but I'm stuck on the important detail of how to do the 100\$\Omega\$ differential pairs for the Rx/Tx. I understand this is important, but what I don't quite get is how to actually calculate the balanced impedance.

From what I understand, I can use this PCB Impedance and Capacitance Calculator (Microstrip) to calculate the characteristic impedance of the individual traces to make them 50\$\Omega\$, then use this PCB Impedance and Capacitance Calculator (Differential Microstrip) to calculate the differential impedance of the two tracks routed together. If this is wrong, please somebody point out my error.

However, the bit I don't understand is that both of those calculations require a distance to the ground plane. This is fine for the tracks from the PHY to the magnetics, but the SMSC app notes recommend no planes beneath the tracks from the magnetics to the connector, so how is this supposed to be calculated?

I'm confused. If someone out there can offer me some pointers it'd be much appreciated.


texts: I want to know how an AC electric magnet works since the polarity of an AC current changing 100 times in each second (for 50Hz mains supply) so its magnet polarity(N & S) also will changed 100 times in each second. But i see AC solenoid always moved in one direction when the power is connected, why?


texts: Petroleum engineer want Electrical engineer help?

texts:
I need your help since I'm not electrical engineer :( . I'm petroleum engineer and I'm building a system to do an experiment.

The system consist of five cell (40 ml) and inside each cell a ball.
These balls must move from side to side. These cells will be mounted on plate and this plate will swing on axis to move the ball. The swing movement is about 45 degree from each side (90 degree total).

Now, I need motor to create this movement.

First option: I'm thinking of using one motor on one side that can change (or reverse) its rotation from side to side after X seconds.

Second option: Or instead of that, use two motors. each one on one side and connector them by rope that pass by the plate. When one of them operate, the second will be switch off and so on.

I don't know which option is better or which motor should I used. For the second option, its possible to be done in the first place ?

Could you, please, help me ?


texts: Altium room moving objects from another layer

texts:
I have found a few other questions with the exact same problem but without answer, and i need to make sense of it because i cannot fathom how stupid it is for a supossedly professional program as Altium.
I have two rooms, one in the top layer and another one in the bottom layer. As most rooms do, they have tracks, vias, and pours, which is expected.

Now, if I move the top room over the bottom room, everything its ok:

But why, for the love of god, if I move again the top room it moves with itself all of the tracks and vias and polygon pours that were on the bottom room? Now, vias I can understand as they are multilayer objects, but tracks on another completely different layer????

Sorry if I sound too snarky. I'm tired of this problem and haven't found a way to work around it.


texts: Multiple NE555 timers, disable retriggering until all have finished

texts:
I plan to build a small timer device that, when triggered, lights up 3 leds. After 30 min, the first goes dark, after another 30 min the second and yet another 30 min later the third.

It's pretty easy to accomplish building three separate monostable NE555 stages that share one trigger button. Yet, only one at a time prevents its being retriggered during its high-level pulse at it's output. Question is: is there an easy way to keep all of the 555s from being triggered while any of them is still activated?

I thought of putting a diode between their outputs and the other's trigger input and putting a resistor between the button and ground, so that an active ouput would pull the other trigger inputs high, stronger than the button to ground would pull them down, and due to the diode prevent them from being pulled down if all outputs showed low-level...

Could something like that work? Something like a only-pull-up-not-down mechanism... Any suggestions appreciated. Thanks!


texts: LED switch on/off issue with wiring (transistors and grounding)

texts:
So my issue is that I am making a circuit that is able to control a light switch remotely. The items I am using are:

-Arduino Uno Rev 3

-TIP31c NPN Transistor

-PS2 wireless controller and dongle

-100W LED

-4x 9V batteries (in series)

I have used the controller and dongle before with no issue, and I am receiving commands from the controller so that is not an issue. The LED does light up when connecting the batteries directly to them so that takes care of any power issues. The arduino does do its job by sending voltage to the designated pin where the supposed base of the transistor is suppose to be. So that leaves me with the issue of whether I am wiring up the transistor wrong, or if the issue lies in another place.

The link to where I purchased the transistor is; www.amazon.com/gp/product/B01N9N1RZG/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=A26TJE9XKYYNGN

The other part that may be an issue is the grounds but I am unsure, this is the schematic of the current circuit:

Should it be like this ^^

or like this^^

Another theory that I have is, if the arduino is being powered by a computer, would it be able to deliver enough voltage/current to the base to allow the electricity to flow? Any advice would be much appriciated, as I need to complete this project by March 21st, 2017. Thank you for your time!


texts:
Turned on the diode means blocked current? or vise versa?
That made me confusing.
In here VCC and VEE is +12V, -12V. so, if Vin is 6V then upper OP amp will give +12V.  and below OP amp will give voltage -12V. then D1 will be not block and D2 will block. right? so..D1 is turn on? or off? How i have to call that?


texts:
i have a question regarding cable length for a pushbutton in a home automation project.

I would like to have some light switches (regular switches from home shops) connected to my arduino - so 5v - and have that signal back to my arduino next to the electrical core of the house. My question is how long can i go with a good quality shielded cable with the 5v output from Arduino (or another source) to the switch (and back to my arduino.

Thank you for your answers.

Cheers

Tim


texts: Can a premium HDMI cable outperform a standard cable?

texts: Assuming two cables both conform to the same standards (e.g. HDMI2.0, high-speed, ...) is it possible that a premium cable will outperform a standard cable when using an objective benchmark that measures the quality of picture/audio? Or what experiment would show that a premium cable has a benefit over an 'ordinary' cable?


texts: Op Amp - Positive vs Negative feedback from the component level

texts:
I am beginning to study the internal circuitry of the LM741 op-amp. For the most part I understand each section and stage. I am now trying to realize what I already know about op amps but in the context of the overall schematic. One question that has come up is the difference between positive and negative feedback and why they make the circuit act so differently.

Why does positive feedback drive the circuit into saturation? In analyzing circuit I see that an increase in In- causes the collector of Q4 to increase, which eventually makes the output decrease (due to the common emitter, Q17), and vice versa. I think I understand how this will create equilibrium between the two inputs. However I am confused about the positive feedback. If In+ increases, collector at Q4 goes down, and therefore Vout increases. Then it seems like it would continue happening until it is saturated. So is the result of the two different operations the fact that the second stage is fed by the collector of Q4 (Inverting side) and not Q3? Am I thinking about this correctly?

Do all op amps feed the next stage with the inverting side of the diff. amp then?


texts: Simplest way to create regulated 400VDC from 12VDC

texts:
I would like to create a regulated 400VDC supply with relatively low ripple (less than +-1VDC ideally). Required current is very low (< 1mA). V_IN is 12VDC. Currently I have a boost converter that is able to create well above 400VDC based off a NE555 in astable configuration and a small MOSFET. It works very well and I use constant switching frequency (30 kHz) and adjust the duty cycle so that the output voltage is correct.

However, when the source is loaded, the voltage breaks down and I do have slightly varying load and would like to ensure that the output voltage is regulated to around 400VDC. Which approach (IC or discrete) works well and which works the easiest?


texts: Electronic soldering and repair for a newbie

texts:
So, recently, I've been trying to get more skilled with electronics to prepare me for college, starting with soldering. I mentioned this to someone I know, and he gave me his broken E-Cig, saying I could try to fix it for some experience, and that he'd pay me if I could get it working. I've looked up some basic stuff, but I'm still pretty nervous, and wanted to know if any knowledgeable people would be willing to give any advice to a newbie like me (I'd ask someone else for help, but no one I know is very good with electronics).

I'm including some photos below. From what he said, the only thing wrong is the tip of these two red wires from the mouthpiece to the H+ and H- spots on the main pcb, which snapped off when he dropped it.
Any help would be appreciated, but I'm really looking for:

General steps to how you would fix it
Soldering tips for someone who's never done this before
How to get the solder that's currently in the hole out... I saw something online about heating it up and using a solder sucker, but I don't have one of those. Any other way I can fix this?

Thanks a lot guys!


texts: How do I add dielectric Breakdown Voltage of air in Multisim?

texts: For my simulation, I need to add a component that represents air with dielectric breakdown voltage of 1 kV. How do I do that?


texts: What current should I charge/discharge my 12V lead battery at?

texts: Here are the specs listed on the battery:


texts: How to implement a self tuning PID-like Controller

texts:
I am trying to write a micro-controller program for controlling temperature in a system with the following characteristics:

output can only be On or Off, with fixed cycle frequencies (~2-10 per hour)
The plant is slow to respond (measurable changes in temperature take a long time > 10 minutes).
The plant loses temperature based on environmental conditions.
the set-point can vary in large steps based on user demand.

I am writing a controller that aims to minimize error, as well as adhering to the cycle-rate provided as an input.

This could easily be done with a PI controller and it's output converted to the duty-cycle.  The problem is that the program needs to auto-tune and choose correct Kp, Ki constants and adapt to varying environmental conditions and changes in heating capacity.  Therefore, tuning the PI controller in advance is not too useful.

Using an actual PI or PID is not a requirement.  I'm open to use of Fuzzy-Logic if it helps, also have a machine-learning algorithm on the chip that models the system response and heat-loss (linear approx.) which suggests information about measured step response. Just don't know what to do with that information.

A couple of posts suggest I could use the modelling data to tune the PI on-line, as well the lab-view manual that suggests I could use Fuzzy-Logic to tune the PI.

My question is, what is the best approach for this kind of scenario (e.g. PID, fuzzy-pid, convolution, etc) and how would I go about actually implementing it in software/practice.

I'm not a EE so any input would be greatly appreciated.


texts: Block bids and offers in electricity markets

texts:
Why are offer curves and willingness-to-pay (or bidding) curves represented as blocks in electricity markets? What does each block signify?

I'm trying to simulate an electricity market using MATPOWER and came across this section. I'm trying to figure out what the block offers and bids mean in Step 1.

Here's an example from the manual:


texts: Using a Kalman filter requires a truth value?

texts:
I have some accelerometer data that I need to filter and clean. However, based on the online examples that I see, the filter requires what's called a "Truth value". The code is based on this:

http://scottlobdell.me/2014/08/kalman-filtering-python-reading-sensor-input/

Now for the truth value for my accel data, I was wondering if I could generate it by applying a smoothing function to my dataset, then using that as the truth value. The image below shows my accel data, with the green part showing the smoothed data. It is using the "Blackman Tukey" smoothing algorithm. However, you can see that it is not good at processing high frequency signals. Nevertheless, i have a "rough truth" value.

My question is, can I use this smoothed value as my truth value in my kalman filter?


texts: Moral Designs - Or - My Parts Match Your Parts?

texts:
So I was designing a front end for a 16bit ADC and had settled on a design and preliminary values. I decided to google around and see if any other designs could help me make things better when I stumbled upon a project that used the exact same parts with the exact same intent but with different descrete values.

This project I found was for an old product from 2004 that the company had open sourced the hardware for but previously it was closed source.

My question is simple. When you are designing something and it is very close to a competitors design and you are both using that design for the same purpose, are you liable for intilectual property infringement? I do not want to design something and start selling it to find out a year later bigOrg LTD. Holds IP rights on that "style & usage" of said part and I owe them $5M...

This might not seem to happen that often but I have run into it twice so far. I designed a logic analizer and to scale the unknown 0-7V input into the TTL range of my buffer I made a 1M/5M/1M divider between 5V and GND, input with a 330ohm resistor and 10pf cap to my buffer. I got to these values using spice and making a way to really ram in a logic change without going over specs. About 6 months later my buddy sent me a hack on the ZeroPlus Logic Cube and they use that exact layout with only two resistors of different value.


texts: Component that plays single .mid music file?

texts:
Is there a component, (that is not Raspberry Pi or other mini computer it would be an overkill), that I can use to play a MIDI music file on loop? Even by uploading it on it or program it to the tune.

It would be a very simple circuit:

It would work like those music playing postcards, so there will be a switch, but nothing more complicated around it.

I have only base knowledge in electronics so my search for this wasn't successful. I need a component or circuit that does this. I could build it if needed, but I would prefer a ready to use component if exists.


texts: differential output amplifier formula derivation

texts:
i was reading Art of Electronics book and then I counter this circuit which is differential output amplifier the author just give the formula without derivation , (i try to derivate it my self and it took me many hours and i fail )can somebody prove this formula with a circuit analysis equations
thanks [![enter image description here][1]][1]

[1]: https://i.stack.imgur.com/1sRV7.png


texts: 1960's video showing early computer design & simulation of a low-pass filter circuit?

texts:
I ran across this IBM computer aided design and simulation software demonstration from the 1960's in the video The Incredible Machine (1968)

The gain vs frequency plot shows what looks like the characteristics of a low-pass filter, but is that what's shown in the diagram? Could the 3-terminal device at the bottom be a transistor?

The GIF was made at about 02:44 in the video.


texts:
The Xilinx web page for the FIFO Generator IP states:

Key Features and Benefits

    FIFO depths up to 4,194,304 words
    FIFO data widths from 1 to 1024 bits for Native FIFO configurations and up to 4096 bits for AXI FIFO configurations
    ...

This is certainly a mistake, but I'm asking for confirmation in case I am missing something.

The IP's documentation states that the depth is up to 131,072 - which I believe is correct.

Common Features1

    Supports Native, AXI4-Stream, AXI4, AXI3 and AXI4-Lite interfaces
    FIFO depths up to 131,072 words
    ...

1 FIFO Generator v13.2, LogiCORE IP Product Guide, PG057, p. 9


texts: Understanding inputs and outputs on a multiplexer chip

texts:
I'm trying to understand the chip selects for some hardware I'm reverse engineering.  There are more devices than CPU chip select lines so they are multiplexed using a variety of other inputs, including certain address lines being high/low.

The multiplexer I'm trying to figure out is a 2 to 4 output one (Toshiba TC74VHCT139AFT)

If it is 2 to 4, why are there 3 inputs A, B, and ~G?

Also, the truth table mentions active low G and the 4 outputs Y0-Y3.  I've attached a pic of the truth table.  The schematic I'm looking at shows inverters for those pins (also posted an image).

Do the inverters in the diagram mean that the signal is flipped on its way in/out?  Or is this just a reflection of how the chip behaves?  Based on how things behave, it seems to be the latter, but it's confusing.  The CS lines out of the chip are active low as well.

Am I reading the truth table correctly that I'm looking for one of the Y outputs to go low to show it is "selected"?


texts: Multisheet design power rail as port or as power port

texts:
I am learning Altium Designer and now I am working on some multisheet pcb project, which consists of Power Supply among other things, which is implemented with
Texas Instruments's UA7805 Regulator for +5V/1.5A power supply rail. This rail is named in schematic as +5V_DIGITAL. However, because of multisheet design (with root sheet), how do I declare this power rail in Altium, as Power port:

or as Port:

? If rail should/must be declared as Port, then what type of port it is (Unspecified, Output or Bidirectional)?


texts:
$$ F(A,B,C,D)= Σ(1,7,8,9,13,15) $$
if possible, simplify then, make it by using decoders and logic gates.

I've simplified it by Kmap and found as $$ F = \overline{B}\overline{C}D + A\overline{B}\overline{C} + A\overline{C}D + BCD $$

but how can I supply using decoder. Unfortunately, I don't understand decoders. Thank you for your help.


texts:
Is there any way to connect a sensor that outputs pulses in a PC system?
For instance, it can be connected via raspi via the GPIOs. Is there another and most robust way to get the input to a PC?


texts:
So currently mucking around with the ADC on my PIC16F917. I got single button functions going and all works well.

What I'd really love help with, is how to make the MCU accept 2 inputs, without the second being an ISR.

How can I modify this code, to make it so when, say AN1 goes > 512, PORTDbits.RD1 goes high, alongside AN0 and RD0. Acting like two separate systems, but working simultaneously. Is it actually even possible?

Thanks again, Ezra

#include <xc.h>
#include "config-bits.h"

#define _XTAL_FREQ 4000000

void delay()
{
    int i;

    for(i=0; i<5000; i++)
    {
        /*Timer Stuff*/
    }
}

int main()
{
    TRISD=1;                    //Set all D pins to input

    TRISDbits.TRISD0 = 0;       //LED output
    ANSELbits.ANS0 = 1;         //Select ADC input

    ADCON0bits.ADFM = 1;        //ADC result is right justified
    ADCON0bits.VCFG = 0;        //Vdd is the +ve reference
    ADCON1bits.ADCS = 0b001;    //Fosc/8 is the conversion clock
                                //This is selected because the conversion
                                //clock period (Tad) must be greater than 1.5us.
                                //With a Fosc of 4MHz, Fosc/8 results in a Tad
                                //of 2us.
    ADCON0bits.CHS =  0;        //select analog input, AN2
    ADCON0bits.ADON = 1;        //Turn on the ADC

    int result;

    while(1)
    {
        __delay_us(5);                  //Wait the acquisition time (about 5us).

        ADCON0bits.GO = 1;              //start the conversion
        while(ADCON0bits.GO==1){};      //wait for the conversion to end

        result = (ADRESH<<8)+ADRESL;    //combine the 10 bits of the conversion

        if(result > 512)
        {
            PORTDbits.RD0 = 1;
            delay();
            PORTDbits.RD0 = 0;
            delay();
        }
        else
        {
            PORTDbits.RD0 = 0;
        }
    }
}


texts: I'm hearing impaired. I'd like to dampen all the sounds around me filtering out all the stuff I deem unworthy of reaching my ears like the sound of my cars engine, computers fan or the rattling of dishes in the kitchen or any other ambient noise. Is it possible to create a system of noise canceling like bose headphones without say the headphones but isntead wearable speakers or strategically placed speakers?


texts: Complex Voltage and Current in Steady State DC Circuit with Nonlinear Component

texts:
I was trying to solve the following circuit that has a nonlinear component:

simulate this circuit – Schematic created using CircuitLab

B is the nonlinear component with the following characteristic:

$$
i =
\begin{cases}
3\cdot (v-3)^2 +1,  & v \geq 1 \\
0,                  & v <    1
\end{cases}
,\quad[\,i\,]=\mathrm A \,\,\,|\,\,\,[\,v\,]=\mathrm V
$$

Firstly, I found the Thévenin's equivalent seen by the nonlinear component:
$$
\begin{array}{c|c}
E_{th}=8\mathrm{V} \quad & \quad R_{th}=1.6\mathrm{\Omega}
\end{array}
$$
Then, by KVL, we have:
$$
\begin{alignat}{1}
v &= 8-v_R \\
&= 8-1.6\cdot i           \\
&= 8-4.8\cdot (v-3)^2-1.6 \\
&\implies 4.8v^2-27.8v+36.8=0
\end{alignat}
$$
Solving the above equation, we have two pairs of possible answers:
$$
v_1 \approx 2.0478\mathrm{V} \implies i_1 \approx 3.7201\mathrm{A} \\
v_2 \approx 3.7439\mathrm{V} \implies i_2 \approx 2.6602\mathrm{A}
$$
If \$i=0\$ we have \$v=8\$, but \$i=0\$ only if \$v<1\$, so this situation never happens.

Secondly, I was trying to show that superposition is not valid for this circuit. That's when something strange to me happened. If the current source is inactivated, we have the following circuit:

simulate this circuit

Again, by KVL, we have:
$$
\begin{alignat}{1}
v &= 3.2-v_R \\
&= 3.2-1.6\cdot i           \\
&= 3.2-4.8\cdot (v-3)^2-1.6 \\
&\implies 4.8v^2-27.8v+41.6=0
\end{alignat}
$$
Solving this equation, we have the stranger thing:
$$
v_1' \approx 2.8958+j0.5299\mathrm{V} \implies i_1' \approx 0.1901-j\,0.3312\mathrm{A} \\
v_2' \approx 2.8958-j0.5299\mathrm{V} \implies i_2' \approx 0.1901+j\,0.3312\mathrm{A} \\
$$

My questions:

What is the interpretation of these complex voltages and currents? How can a steady state DC circuit have complex voltages and currents?
I tried to simulate both circuits in Multisim 14. For the first one, I got only the first pair of results (\$v_1 \approx 2.0478\mathrm{V} \implies i_1 \approx 3.7201\mathrm{A} \$). How would I get the second pair?
Simulating the second circuit I got a simulation error ("Transient time point calculation did not converge. Simulation canceled"). Why did this happen? Why does simply removing the current source causes the simulation to fail? Is there any way to make it work?

Note: For the nonlinear component, I used NON_IDEAL_RESISTOR, the only one with the option "Current = f(voltage)"

  Multisim 14 Log

  ======= SPICE Netlist check completed, 0 error(s), 0 warning(s) =======
  Transient time point calculation did not converge
  Simulation canceled

  Output from instrument analysis
  |   |   Starting dynamic Gmin stepping
  |   |   Dynamic Gmin stepping failed
  |   |   Starting dynamic source stepping
  |   |   Dynamic source stepping failed
  |   |   DC operating point failed. Resimulating with UIC
  |   |   TRAN:  Timestep too small; initial timepoint: trouble with node $2
  |   |   Error: doAnalyses: Timestep too small (Transient time point calculation       |   |                      not converge)
  |   |   tran simulation(s) canceled (Simulation canceled)


texts: SMA Differential LVDS to DB9 and termination

texts:
I want to connect a differential LVDS signal to a DB9. It seems pretty straightforward but I just want a sanity check and after seeing this (Connect SMA to a regular pin/wire), Im doubting myself.
The differential LVDS signal is from 2 SMA ports. I imagine I just need to connect the inner cores to the DB9 input and connect the outer cores to some metal outer part of the db9 (I guess the screw connector or the outer shell of the db9). This will look janky, but I imagine gets the job done?
Any feedback would be appreciated. Thanks!
EDIT: In hindsight, I realized my DB9 has a ground pin I can connect both to, but I did realize also that the DB9s characteristic impedance termination is 100Ohm differential. Does that mean each port is 50 Ohms and I'm good to go or since both inputs from the SMA are 50, that makes my input impedance 25 ohms?


texts: PIC16F77 ADC not producing 0v result with 0v input

texts:
I've set up a PIC16F77 to repeatedly sample an analogue DC signal. The problem is when I apply a 0v signal, the ADC does not read as 0x00. It's an 8-bit ADC and at 0v reads about 0x05 - 0x06. (I'm using the Vref pin for scaling, and have set it to 2.55V).

What I have done to try to fix the issue:

A well regulated 5v power supply
Smoothing capacitors on the Vref pin
Smoothing capacitors on the power supply
Tied all other analogue inputs to ground
Increased the acquisition delay to about 40us (recommended is 16us)
The signal to the analogue inputs is in the order of a few ohms - the recommended is less than 10k

The datasheet says +/- 1LSB should be possible, and I'm mystified. Can I expect better from this PIC? And how can it be achieved?

Thanks!


texts: JTAG connector - large pitch to smaller one

texts:
I have a Segger's Jlink EDU probe which I used for debugging and programming various ARM based MCU's. But now I have to work with this LPC4088 QS board which has a smaller pitch 20-pin JTAG connector that usual one. So I am searching for something like this:

to transform my large pitch JTAG cable to smaller pitch one. BUT The one on the picture (the smaller one) has only 10 pins while I need 20-pins. Does anyone know of any similar circuit like the one on the picture but with two 20-pin connectors (larger and smaller one)?

This is the schematics of the JTAG interface on my board. It looks like more than 10 pin's are needed:


texts:
The enc28j60 manual says that the maximum SPI clock is 20MHz, but doesn't specify the minimum pulse width. This is important for microcontrollers such as MAX32660 that cannot drive the clock 50/50 at certain speeds (like 16MHz, which is the only choice between 12MHz and 24MHz).
How could I find the pulse width spec?
My enc28j60 seems to work perfectly fine at 3.3V on a 48MHz SPI clock. However, before I fixed a bug in avrlib (it wasn't checking if the previous packet was done transmitting before overwriting its bytes in the buffer with a new packet) it wouldn't work on a 66/33 duty 16MHz clock. So it just made me wonder whether clock pulses shorter than 25ns (in this case 21ns = 1/48MHz) are expected to work or not (even though they appear to).


texts: PCB layout help for MEMS oscillators and clock drivers

texts:
I have this SIT8009 MEMS oscillator at 125MHz frequency (also the same with an OSC52 from SiWard at 25MHz) followed by a 1-to-4 clock driver to distrubute the clock to multiple ICs.

When layouting, I always find myself asking what is the "best" layout practices for them, since they are high speed signal sources and since I almost always have EMC problems related with these frequencies. This doesn't mean of course that the source of the problems are these oscillators. But I nevertheless look for ways to improve the layout at this corner.

Do you have any specific guidelines you follow when you layout such components?

Some of which I use are the following:

The driver is physically placed close to the oscillator
The decoupling capacitors are carefully placed close to the supply pins
I typically use a ferrite bead to create a filter at the power supply
On all layers underneath the oscillator and the driver I don't route any signals at all
All clock outputs are provided with a series resistor used for termination purposes

Do you have anything else to propose?

For example would using ferrite beads at the clock outputs help anyhow? I mean by dumping higher clock harmonics
One "expert" once told me to do the following: practically to use a separate 3-sided GND "Island" (more like a peninsula) underneath the components which is only connected on one side to the rest of the GND plane. The side where also the outputs go out. Do you think such an approach would help? I suppose this ensures that you don't induct noise on other signals nearby. Does it do anything else?


texts:
New Intel and AMD processor feature processors with 14-22nm gate lengths, and this information is widely available. However, when it comes to microprocessors (PIC, ATMEGA) I have not been able to find this information. Is it "classified" ?

As to ARM processors, since ARM is an architecture, who defines the technology to be used when manufacturing say an Cortex-A8? I used this example because the Beaglebone Black uses a ARM Cortex-M8 manufactured by Texas Instruments, so which of these entities sets the technology? Again, unable to find information related to this.


texts: Any better way to determine source of light by analyzing the electromagnectic spectrum of the light

texts:
Project overview

I am tasked to develop a microprocessor based device that when shown a light upon, can determine the source of the light (Natural light, Flourescent Bulbs, LED Bulbs, Incandescent Bulbs, Flame - Forest fire). At this stage, only the visible light is considered.

From my research, the only way to differentiate the source of light is by analyzing the emission spectrum and matching it closely to known values. Example:

Solutions considered

Measuring RGB composition ratio of the light

I have considered going this route as it doesn't seem too complicated, smaller device, can be integrated easily into the bigger project as a forest fire detector and even suggested by my supervisor.
But I have doubts that this would be very accurate as some light sources might have close values (the intensity is what is being measured on a ball park wavelength).

The sensor I am looking at currently is the Hamamatsu’s S10917-35GT RGB color sensor, sensitive to only the required wavelengths.

Building a high resolution spectrograph with a diffraction grating film

This route is much more complicated and requires external processing of the images to determine the light source. Basically, you build a spectrograph with a diffraction grating film and a high resolution camera. The image is processed with a computer software to plot the emission spectrum graph and you can analyse the graph to determine the light source. Development guide is here

Unfortunately, this is not very convenient as we would prefer the device's primary objective to function on it's own without any networking.

So, the question

Is there any drawback on my first solution?
Is there a better solution? Preferably can fit on a standalone device?
This would probably be far fetched but is there a sensor out there that can analyse a light emission and provide intensity values on a range of chosen wavelengths? Or atleast something that would help me build a device that does such.


texts: Do devices on AC currents have flicker on and off?

texts: For current to alternate between positive and negative it must be zero for a split second. Does that mean devices receiving AC current are flickering on and off? This seems like it would have some bad effects.


texts:
I was looking around at some other questions that were asked dealing with how to use an LED to indicate UART activity.  One of them provided the image below, however it was stated in the comments that factors such as cable length and baud rate will cause significant signal degradation.

Other questions recommended using a MOSFET to drive the LED instead.  I haven't dealt with those before and wanted to confirm some of the specifications before proceeding.

When choosing a MOSFET for this portion of my circuit I came across the BSS138 N-Channel on DigiKey and the specs I don't exactly understand/want to confirm are adequate are:

Current - Continuous Drain (Id) @ 25°C:  200mA (Ta)
Drive Voltage (Max Rds On, Min Rds On):  2.75V, 5V
Vgs(th) (Max) @ Id:  1.5V @ 1mA

These are my own interpretations for the three items:

Current: The maximum current that the MOSFET can switch.
Vgs(th): The threshold to switch the MOSFET (<1.5V: Off, >1.5V: On).
Drive Voltage (Max Rds On, Min Rds On):  This is one I just really do not understand.

With that being said would the BSS138 be suitable for the following circuit and not have any major affect on the communications?

simulate this circuit – Schematic created using CircuitLab


texts:
I am designing a low-power opamp (differential amplifier) that will be used in the low-power consumption devices, e.g., power management circuits, portable devices, or energy harvesting circuits. I am new to this area and not any expert, but this idea just came to my mind after taking an Analog Circuits course at my university.

I thought the power consumption would be around 200 uW, and operating voltage would be around 1.3-5 V. Thus the maximum quiescent current would be 200uW/5V = 40 uA. The following is the general idea of the above features rewritten:

Maximum quiescent current ~40 uA
Operating voltage 1.3-5 V
Gain bandwidth product ~500 kHz

I have searched through many textbooks and have done several SPICE circuit designs, but still couldn't achieve the above features with a good stability characteristic. (For example, the bias and start-up circuit in my design consumes a significant amount of quiescent current even operating at 1.3 V. Or when I tried to improve the stability by adding compensation network, the gain bandwidth dropped below a few of 10 kHz.) I also tried to reverse engineer some chip like TSU111 but the schematic is not revealed (unlike the ubiquitous 741 opamp which is quite well-known ?). It seems to me that it is almost impossible to reverse engineer the commercial chips out there.

Is this just a secret of the company or is it just an ongoing topic in the research area?

I know this question is too broad. But I would like to ask some of the good practice or the general procedure in "designing/reverse engineering" the low-power opamp like in the commercial chips. The answer could be any that answers the following questions:

What considerations should I take into account in the low-power design? (Operating in the subthreshold region to get a low quiescent current? Adding more stages to get more gain, but that means more quiescent current and thus power consumption?)
Where in the circuit should I first start sizing the W/L ratio of the MOSFET? (I usually start at the bias circuit and try to size the W/L ratio to get the current that meets the specifications that I want. Any other considerations?)


texts:
I'm working with an ATmega328P and I wanted to interface with the flash memory writing data to it with the macros provided by avr-libc. This is the memory map for my chip:

(source: avr-tutorials.com)
I don't understand where the program code is exactly located when compiled. What I mean is: How can I be sure the address I use in boot_page_fill and boot_page_write is not used for the program code? Do I need to use the "–section-start" linker option to move the program code to a specific location and be sure the flash page I'm going to use doesn't overwrite that code?
NOTE: The data to write in the flash is unknown at compile time.


texts:
I'm designing a generator using a nitro engine and a motor. My design is similar to the YouTube video that I linked below. My main concern is to generate 12 V of electricity.

DIY 220v Dynamo Generator Using Nitro 2-stroke Engine

Nitro engine : Nitro Engine Specification

The nitro engine specification is in the description box of the YouTube video. But there is not information for the motor used.

The nitro engine RPM is 28,000. Do I need to find a DC motor which has lower or higher RPM than the nitro engine? I don't really understand what the relation is between the parameters of engine and motor. It is quite difficult to find a DC motor which operates at more than 28000 RPM. In my case, the shaft of the engine drives the shaft of the motor.

How is the RPM of the engine and motor related? With the specification of engine and motor, how do I ensure that I produce electricity at 12V? Is there any formula that I can use to calculate?


texts: Do multi-channel opto-triacs with common pins exist?

texts: I am designing a circuit with many (4-128) copies of the same component. It's a 4-pin opto-isolator with opto-triac output. I am aware that the pin spacing and package width can't be much less in order to maintain isolation. However, outside the IC I am tying all of the cathodes (or anodes) together, and tying all of one side of the AC together as well. It would save me a lot of IC footprint if I could find dual or quad versions of this device with those legs already joined and brought out as a single common pin. Does such a device exist?


texts: SPI programming for ATtiny MCU - will it be influenced by TWI pull-up resistors?

texts:
I am wondering if this could be the case for an ATtiny84 which has some common pins used for both SPI and TWI (they are part of a so called USI - Universal Serial Interface).

Basically I am asking this question - SPI and pull-up resistors
with a few changes:

SPI mode will only be used for programming the chip, then only TWI mode.
The voltage problem is not there: everything will run at 3.3V


texts: Will a coil of wire acting as an antenna improve reception/transmittance?

texts: I thought that a coil of wire might be good as an antenna. If this is valid would using said antenna improve reception and transmittance if used? Would an antenna of this kind be stronger with more turns in its winding?


texts: Possible to measure output of each battery in a battery bank?

texts:
I've been working on a small project to add electrical to my utility trailer.  I have two 12V 20Ah lead acid batteries wired in parallel for running a mix of lights, a winch, cameras, a ventilation fan, inverter, etc.  (Basically more of a fun, learning project).  The specific batteries are:

https://www.amazon.com/gp/product/B00KC39BE6

Originally I was going to keep them separate and divvy up the electrical devices between them, so I purchased a battery meter for each one:

https://www.amazon.com/gp/product/B01N642QV6

I've since learned about and changed over to wiring them in parallel connected to a single charger, but now I'm wondering if there is an arrangement where I can still use the meters to read each individual battery without reading the output of the overall bank?

I tried to Google this, but I get the feeling that if this is feasible, I don't know the correct terms to search for.


texts:
I've had my ENGTX480/2DI/1536MD5 GPU for 3 and half years now.

Over the past 2 months it started causing trouble. At first, it started seldom displaying big zones with

weird color, but simply turning my TV off and on again and it got back ok. Then it got worse. Under windows 7 x64, 340.52 driver, I got wierd pixalated screens, then screen would go black and the pop up, "driver stopped responding and was restarted" or something like that. Soon followed by 116 BSOD. It got more and more often. And completely random. Usually starts on windows, but once it happened, also occurs on boot screen. I can still use it, though I can never rely on it. It got unstable.

I have double checked temperatures, they were all under 60 C, under 69 worst cases. Auto cooling was working perfectly fine. I switched PC&C 910 W for a Corsair 750W, and nothing changed.

I've cleaned the gold fingers at first, checked for poor contact. Then dismounted the video card and got it all clean - no warranty anymore. The same goes on.

I have changed the video card for an old one and it works great, so I am sure motherboard is fine.

It seems to me a classical case of soldering issues over time. A reflow seems to be the last resource. I have checked over the net and the vast majority of people who somehow "baked" their GPUs and MBs got them working or living again, but for just some weeks/months. It seems clear to me that baking helped by changing the state of the solder, but done under the wrong profile!

Like many of you guys, I am a licensed electronic engineer and I have means to use a fully programmable oven. I mean an oven that supports programmable temperatures ramps and times. However, I can't find any temps and time profiles that are safe, indicated by any manufacturer or sustained by engineering professionals at all. Just found "i tried this", "do that", but no real references.

Does anybody know the correct complete profile for reflowing a GPU??


texts: USB CDC connection (plug / unplug cable)

texts:
I am having a issue with USB CDC (running in a LPC1788). If I power up a mother board with the USB cable (NXP device) already connected, the O.S. (Linux) does not identify the device, but if I unplug and plug it again it is identified and works fine. The same thing happens if I reset my NXP board, the O.S. does not identify the NXP device until that I unplug/plug the cable.

I checked the code, and what happen is that the application stays forever in the while (!USB_Configuration); loop.
Is necessary some configuration on USB device to that the device do an auto-configuration when it is already plugged?

I am using the example code from 177x_8x_PDL_110602 package from NXP.


texts: How to detect a signal if it is greater than VDD or smaller than 0?

texts:
I need to detect a signal if it is greater than VDD or smaller than 0.
I can't use comparator because the input signal is outside of common-mode input range and I have only one power supply VDD.
Is there a simple way to do that?


texts: What happens if the input high and input low of Buf2 become the same?

texts: What happens if the \$V_{IH}\$ is equal to \$V_{IL}\$?


texts:
I'm trying to understand the function of the constant current regulator CCR and the zener diode 1N5338. I do have more questions but these two components is probably a good start.

I understand that a zener diode is voltage regulator but not sure why it is included. As for the CCR I have no idea what its purpose is in this circuit.

The link to the web page where I found this:
https://www.electronicdesign.com/power-management/article/21801456/current-limiter-offers-circuit-protection-with-low-voltage-drop


texts: Transformer winding ratio vs actual winding count

texts:
Output voltage of transformer depends on ratio of winding count on primary and secondary coils, but is there an impact on transformer performance by actual winding count?

Say, i want to have 1:2 ratio, i could wind 10:20 or 100:200 windings.

In general, more windings - bigger the resistance, inductance and cost. Is there any point in winding more or is winding count kept to absolute minimum? How minimal winding count is determined?


texts:
I have a graphics card with a dead cooler. I have a replacement cooler for it, but the graphics card is a bit non-standard and the cooler won't fit --- the heat pipes hit some components on the board.

As said components are a big, chunky capacitor and a two-pin inductor, all connected via wires through the board, it should be easy enough to move them to the other side of the board to make room for the cooler.

Unfortunately I seem to be totally unable to make the solder on the board melt.

I have a 70W gas soldering iron. It melts my solder fine. I've heated the joints up as much as I dare and they don't even show signs of softening. If I add some of my own solder to the joint, I can then melt that, but the original joint stays solid.

Is there such a thing as high-temperature solder? Would they have been likely to have used it on a graphics card? I'm aware that this kind of PCB is likely to have a thick copper ground plane, which will suck away heat from the joint, but that doesn't explain how I can melt my solder but not their solder in the same joint.

The soldering iron does have a hot-air-gun mode, but I have no experience of that and would rather not set fire to my graphics card...

(I want to get the components off intact because I need to attach them again. The capacitor is easily replaceable, but the inductor is just a black cube with 1R0 written on it, and I'm not confident of my ability to find an exact duplicate. If I cut the pins it will then be too short to reattach.)


texts: power network consumption vs network resistance

texts: I have a simple question. Based on Ohm's law, \$V=I\cdot R\$, by increasing the resistance, if the voltage is fixed, the current will drop. By dropping current, the consumption or the loss will drop (\$P=V\cdot I=V^2/R=R\cdot I^2\$). So, the question is: does increasing total resistance of network, result in less consumption?


texts: What are the effects of trimming the diameter of a wire down to half its gauge?

texts:
I have a three-phase, 4 AWG 259/28 stranded power transmission cable (3 conductors total) running ~200m into a slip ring. The only way to connect to the slip ring is by using its 8 AWG pig tails. These pig tails are rated 600V and 40A, which is sufficient for our needs.

I would like to trim down each of the 4 AWG conductors so they can fit into an 8 AWG butt connector or c compression clamp to splice to the pig tails. As far as I can tell, when trimming a conductor down you are simply changing the resistance/length of the cable in that area and its rated amps.

When trimming the conductor from 4 AWG to 8 AWG, would the mΩ/m of the trimmed section shift from 0.8152 to 2.061, as shown in wikipedia's table on wire gauges, or is there more going on here than I think?

Since the diameter of the 4 AWG conductors will suddenly change, will there be power transfer or heat issues that I am unaware of?


texts: Can I safely substitute a 4.7uF cap for a 5uF cap?

texts:
I'm working on a circuit that calls for a couple 5uF caps. I have 50v and 25v 4.7uF at my workbench. No cap voltage is specified in a schematic or parts list. The circuit has 12VDC coming in, one negistor that'll be connected to the path of the caps (though downstream), so I think the 25v will be sufficient.

But is it safe to substitute 4.7uF for 5uF? What's the worst that can happen by having less capacitance in the circuit by 0.3uF?


texts: How do you find the resolution and sampling rate needed for a certain signal to noise ratio of an analog to digital converter?

texts: For example, I want to convert an analog voltage signal to digital. I want to have a signal to noise ratio of at least 50,000 without aliasing. What sampling rate and resolution could I use to achieve this.


texts:
I have a circuit board that uses the PIC18F2620 SOIC device. I am set up to use the internal clock at 8Mhz and and PLL to get FOSC to 32MHz. FOSC/4 is output on pin RA6/CLKOUT to a logic analyzer. The trace below shows jitter on the clock unlike what I've seen with other PIC18Fs. See below. I used auto-store to capture/overlay many cycle on this trace display. The jitter can be seen on the display.

I am using the following code to set the oscillator:

static void OSC_Init(void)
{
    OSCCONbits.IRCF    = 7;       // Internal Oscillator to 8 MHz.
    OSCCONbits.SCS0    = 0;       // Set system clock to use...
    OSCCONbits.SCS1    = 0;       // ... primary oscillator.
    while (OSCCONbits.IOFS == 0); // Wait until INTOSC is stable.
    OSCTUNEbits.PLLEN  = 1;       // then PLL Enabled (8Mhz x 4 = 32 MHz).
}

My configuration bit settings are as follows:

#pragma config OSC     = INTIO7  // Internal osc, CLKOUT on RA6, port function on RA7.
//#pragma config OSC   = INTIO67 // Internal osc, port function on RA6 and RA7.
#pragma config WDT     = OFF     // WDT disabled (control is placed on the SWDTEN bit)
#pragma config FCMEN   = OFF     // Fail-Safe Clock Monitor = OFF.
#pragma config IESO    = OFF     // Oscillator Switchover mode disabled
#pragma config PWRT    = ON      // Power-up Timer Enable bit: enabled
#pragma config BOREN   = OFF     // Brown-out Reset disabled in hardware and software
#pragma config XINST   = OFF     // Extended Instruction set disabled
#pragma config PBADEN  = OFF     // PORTB<4:0> pins are configured as digital I/O on Reset
#pragma config STVREN  = ON      // Stack full/underflow will cause Reset
#pragma config LPT1OSC = ON      // Timer1 configured for low-power operation
#pragma config MCLRE   = ON      // MCLR pin enabled; RE3 input pin disabled
#pragma config LVP     = OFF     // Single-Supply ICSP enabled
#pragma config CCP2MX  = PORTC   // ECCP2/P2A is multiplexed with RC1

I've read all of the errata datasheets from Microchip, but the internal clock is not listed as having errors.

Is the internal clock of the PIC18F2620 really that unstable, or should I be looking for something else as the cause?

Would the configuration bits set to INTIO7 for monitoring the CLKOUT line affect this?

Should I be thinking about going to a crystal to improve stability?

Thank you for any help and insight to this problem.


texts: Slave wants to send data to Master in I2C

texts:
I have an I2C interface with multiple Slaves and a Single master. If master wants to communicate with any of the slave it sends its address and read from the same.
 But what should be done if one of the slave wants to communication with the master?


texts:
I have a square wave signal of 300 KHz which is 0.2 V to 1 V. It is the output of FP5138 Non-Sync PWM Controller IC. I want to drive a PMOS with this square wave but with the levels shifted to (Vin-12)V ... (Vin-5)V  to Vin, where Vin is 20 to 32 V.

To explain it better, let me try this way (the Vin above and below are different):

      0    1
Vin : A -> B
Vout: C -> D

A: 0.1 V typ, 0.2 V max
B: 1.0 V typ, 1.2 V max
C: D-12 min, D-5 max
D: 20 V min, 32 V max

I have 12V, 1A source (78L12) and Vin source of the converter which has boundaries of D above.

It is going to be a P-MOSFET driver and I need up to 0.3 or maybe 0.4 A spikes for Cgs. MOSFET is not yet chosen.

I have tried to build this circuit but no hope.

I hope I could explain myself.


texts: What is the best way to serve AC power to a 12v - 5v DC regulator with 1Amp current?

texts: What transformer should I use to supply AC voltage in a circuit which is using 7812 and 7805 - Positive Voltage Regulators. I need approximately 1Amp current. What is the best way to minimize the physical volume of the supply? I shall be using an Arduino board from the 5v supply. Most importantly I need low physical volume of the transformer or related circuit to supply the AC voltage.


texts: How to include paths for the C compiler in atmel studio?

texts: I have a folder project and it consists of multiple folder and .c and .h files what is the best way to include them all without including the individual folders?


texts: Two switching wall warts for a regulated bipolar supply?

texts:
Can I connect in series two identical switching wall wart supplies (12 V each) that have no measurable resistance between either DC output pin and either ac pin (measure open and have no ground plug) to make a regulated power supply (±9 V) like this? If so, any hints on how to improve the circuit? I want to power a headphone amp with 300 mA and need a quiet supply.

Thanks


texts: microphone to a microcontroller. very simple

texts: I want to take a microphone and send it to a micro controller.  I then want that microcontroller to evaluate if the audio is above a set db reading and then send a yes or no single to turn on a light.  I need help setting up my circuit. I have never used a microcontroller or a microphone, any extra info would be great.  Thank you.


texts: Identify this symbol: double emitter transistor?

texts:
What exactly does this symbol represent, and how is it different from a regular PNP transistor?

If it is something more than a basic transistor, how would one model it in a simple circuit simulator?

From page 8 of LM78L05 datasheet


texts: Is it possible to combine multiple 5V USB batteries to power a Raspberry Pi for a long period of time (months)?

texts:
I need suggestions or help thinking this problem through. I want to battery power a Raspberry Pi with multiple USB battery packs (for a remote sensing application) with no need to do anything manually.  Solar re-charging of one battery is not really an option.  I am talking about off-the shelf USB batteries sold by companies such as Anker.

Most USB batteries do not allow simultaneous charging while using a battery, so daisy-chaining multiple USB batteries (with one plugged into the RPi's USB) is tempting, but probably out.

I am wondering if I need to design a charge controller circuit that detects when a given battery is low, then switches instantaneously. Does this sound like my best bet?  Is there an off-the shelf circuit or reference design that I should look into for this?

Another idea I had is maybe to connect all the batteries in series.  This would of course produce a higher voltage than the original 5V.  I could use a step-down buck converter to supply the 5V to the raspberry Pi.

Any ideas or strategies are welcome!  Thanks for your help!


texts: What does this multimeter tempco spec mean?

texts: This is the accuracy spec for an Agilent 34401A 6-1/2 digit multimeter.  What exactly does the "temperature coefficient" mean here? Does it mean that the reading will not change by more than 0.0005% (5 ppm) over the whole temperature range 0 to 18C? Or does it mean 5 ppm/C? And why are there two separate temperature ranges 0-18 and 28-55?  (I understand that it gives % of reading plus % of range.)


texts: Can't find the equivalent resistance in this circuit

texts:
I'm trying to self-study this problem. This chapter explained the delta-to-y transformation but I can't seem to find one here.

My best guess is that both resistors on the right are short-circuited which gives them a value of 0. Then you add the two 3 ohm resistor on the left together, and thus the answer 6 ohms.

But I don't know if this is true.


texts: Why do batteries in consumer electronics get used unevenly?

texts:
When changing the batteries of kids toys, remote controls, etc., I test the batteries and have noticed that they drain differently. One will be dead and the other is still in the green.

Why does this happen? Also, at this extreme, why not just have a single battery?

They are typically AA and can be the ones with the product or rechargeables.

Also, why does the device stop and not start using the good battery?


texts: Is MOSFET Drain Source resistance always affected by Drain Source Current? Is there an IC which is not?

texts:
Im trying to measure the voltage of a variable resistor in a voltage divider setup, where the current for the voltage divider is sourced and sunk through a pair of MOSFETS. I assumed that Rdson (drain source resistance) would not be variable/affected by the current flowing through the Mosfet.
This is important to me because i have the resistance values of the variable resistor (which is a crude pressure sensor) plotted according to fixed values of pressure i previously mapped to it.
If i know introduce these 2 unkown resistances of the MOSFETS i have a problem working out the resistance of the variable resistor Rv.

The fig. 6 from a Pmos datasheet PMV65XP shows that drain source voltage Vds (thus Rdson) is affected by the drain source current Id.
My previous plan to sink and source current for the voltage divider directly through port expanders turned out to make the problem more extreme as there were greater voltage drops compared to the MOSFETS.
Is there a port expander or MOSFET or any other IC which acts like a switch, which has a set resistance regardless of current flowing through it? like a relay but able to switch on and off quickly? other shift registers or port expanders maybe?
thanks!


texts: Instrumentation amplifier protection from high voltage transients with minimal signal degradation

texts:
I am looking to protect an INA849 at 2000 or more gain from high voltages of 30 volts AC at various frequencies. Currently I am using an analog switch IC as the only time the high voltages are sent through the sockets are when the microcontroller commands it, so the INA input pins will be disconnected with IC4 and IC6 when sending the high voltage. An interrupt on the ADC microcontroller pin (net name: Out) will also tell the microcontroller to disable IC6 and IC4 (net name Input Switch) when an overvoltage or undervoltage is detected on the ADC pin. (ADC is set to middle of range, 3.3v microcontroller and ADC, 1.6v on REF pin)
Questions:

Is this a suitable protection technique? Should I go for the much more simple (and cheaper BOM-wise) Zener diode approach? I cannot find any schematic for protecting a high gain amp from anything more than electrostatic discharge, or the example in the datasheet with capacitor isolation which will of course remove DC amplification. I can do this if I absolutely must, but I would much rather be able to measure DC as well.
Will signal integrity be an issue going through these analog switch ICs? Is there a better way to save signal integrity with these voltage transients? Would solid state relays be a better option in place of IC4 and IC6? Would traditional diode and resistor protection be better? (as seen in ADC protection area of the circuit) If so, would zener diodes or a sinkable power supply with Schottky diodes be the best solution for protection?
Will this be suitable protection from ESD? this will be a device where the sockets are exposed to human contact.(disregard the safety of the high voltage, that won't be an issue as voltages are not sent during socket contact)

Thanks in advance for any potential insights into these issues.


texts:
I am working on a student project and need to find AVR microcontroller that will suit all project requirements. Here's a simple list:

serial communication (UART),
at least two ADC channels,
PDIP package (for easy soldering, I do not have access to expensive equipment nor do I have skills to perform small-scale soldering),
four I/O ports (excluding UART connections).

I searched on Atmel's website and was stunned when I realised that no device exists that can support these simple requirements.

Here are two devices I considered:

ATtiny2313 (does not have ADC)
ATtiny44 (does not support UART)

I hope that someone will be able to point me to the right device, as I failed to find one to match the requirements. Any recommendations will be much appreciated.

EDIT:

I've noticed that the device selection tool on Atmel's website is not much reliable, at least not in my case. If you list all 8-bit microcontrollers, remove all filters and filter by number of ADC channels (select at least one) and number of UARTs (select at least one), no device in a PDIP package (according to the selection in Packages filter) will be available. You can see the results here.


texts: I have relay connected to raspberry pi that switches the water pump on and off. I would like to add a toggle switch before the relay with a led. When the switch is turned on the led lights up and then the relay can turn the pump on.


texts: How to reconnect nucleo to st-link part?

texts:
It's awkward, but I have accidentally put STM32 nucleo on the washing machine. Though full of soft clothes, the machine managed to tear the ST-link part of the nucleo off:

This means the nucleo is probably still working but I need to reconnect it to the ST-Link part.

My question is, can I connect some of the pins on these two parts to make the whole work again?


texts: Design and Protect Device Circuitry from Inrush Current

texts:
I am designing a device that will be placed between a 220VAC 50Hz power source and a 1100W 7.7A motor load. The device switches power to the load given a relay input and the motor load draws a ~20A inrush current during startup (20A LRA and 7.7A FLA).

The device is powered from the same 220VAC 50Hz source, and I want to know if it is safe / OK to design the device with connectors/cables rated for 16A? This includes a 'CEE 7/7 plug to C-13' power cable and an 'IEC Type F' power socket (which powers the load).

For reference, the motor load's power cable is manufactured with a 250VAC/16A CEE 7/7 plug, which leads me to believe that I would be fine designing my device with the 16A-rated components. I already want to place a 16A slow-blow fuse in-line with the device power...

Thanks!


texts:
Big doubt of the day. For maximum power transfer we use a source impedance equal to the load impedance (conjugate for AC, to be exact). We match for reflection too, but that's another story.
Assuming resistive matching half of the power is on the load side, half on the source side and, with a transmission line, assuming it's lossless and matched, nothing on the trasmission line.
However, usually, matching on the source and/or the load to the line is done reactively (transformers, LC, tees, and so on), with narrow band matching being the theoretical optimum (as in, perfect match assuming perfect components).
How is the power balance in that case? Do I simply use phasors so that the inductive and capacitive reactive power just cancel each other (didn't do the math but that should justify it)? In this case (perfect components and lossless line) the only real power loss would be on the real impedance of the source and the rest should be `usefully' available on the real impedance of the load.
Am I missing something?


texts: adding limiter to reduce distortion in audio amp

texts:
I got this schematic from adafruit. But at high volumes, it exhibits distortion.
A guy from Maxim Integrated referred to include a diode-resistor network(BAV99 and R-100 Ohm) b/w C22/C23 and R8/R9(to be placed exactly as in the PDF).

Adafruit however reconfirmed it by saying, since it is a stereo amp, it should be b/w INL & AGND, and INR & AGND. That is, two of those.

I cant seem to figure out the exact placement in the PCB layout.  In the schematic however I presume it should be placed as if, the BAV99 output pin no. 3 to be b/w C22/R8 and pin 1&2 with R of 100 Ohm connected to AGND.
Then another output pin of BAV99 b/w C23/R9 and the other pins with AGND. I hope you can make out.

But I cant figure out with the PCB layout.

MAX9744 Datasheet

Here are the layers and PCB screenshot.
- Copper Top
- Mask Top
- Silk Top
- Copper Bottom
- Mask Bottom

(Online Paint if required to explain)


texts: What design considerations need to be made when using switch mode power supplies and buck converters in a design?

texts:
I don't yet have a schematic but I am looking to reduce the power dissipation in linear voltage regulators in my circuit. The circuit is powered by a 24V switch mode power supply (110-240V AC to 24V DC) but I need three voltage rails of 12V, 5V and 3V.
What I intend to do is have three buck converters step down the 24V input to it's respective voltage output, before each linear regular to minimise the power dissipation e.g. 14V, 7V, 5V.
The reason for keeping the linear regulators is to minimise the switching noise as this circuit is making signal measurements. Would a design like this make sense attempting, and if so are there any general design rules that need to be considered?


texts: How is the assignment squence in Verilog?

texts:
I want to know if we assign something to a register ( or do anything else ) in a specific clock cycle, this assignment is performed in the current clock cycle or the next cycle? (Setting:  Xilinx , Spartan-3. coded by Verilog via ISE Webpack)

Example:

always @(negedge GCLK)
   foo<= bar; // foo is equal to bar in this cycle or next?


texts: Verilog - arithmetic comparison with part of register

texts:
New to Verilog/HDL and have a problem whenever I try to perform an if/else conditional between two registers of different size. Synthesis completes but I am never able to get it to fit.

For example I have an 8 bit register with options. The lower 4 bits is a number between 0 and 15 I need to test against. What is the correct way to do this?

reg [7:0] options;
reg [3:0] conuter;

always @(posedge clk)
begin
    if(conuter >= options[3:0])
        ... do somthing...
end

Have also tried it this way.

reg [7:0] options;
wire [3:0] options_lowerpartof;
assign options_partof = options[3:0];

always @(posedge clk)
begin
    if(conuter >= options_lowerpartof)
        ... do somthing...
end


texts: VHDL Code for 4x4 Mult: SYNTAX OK BUT ERROR:HDLCompiler:1029

texts:
Hello this is my first post here, I have some code that I've written that I'm having trouble with. I was hoping I can get some help.

I'm having some issues with my VHDL code for a 4x4 multiplier.

The schematic I'm using is below:

Running a Syntax check goes through just fine
but I get the following error:

ERROR:HDLCompiler:1029 - "T:/Multiplier/mult.vhd" Line 26: No index value can belong to null index range
ERROR:Simulator:777 - Static elaboration of top level VHDL design unit mult in library work failed

I was able to find something similar to the first Error:
https://forums.xilinx.com/t5/Simulation-and-Verification/HDLCompiler-error-1029-in-a-XilinxCoreLib-VHDL-file/td-p/153914

and he was able to fix his error by changing the size of his std_logic_vector

But I've used up all of my vector assignments and all of my signals are defined for my sumouts and carrys. The half adder and full adder source codes attached to the project were tested and working.

Any idea? The code is below. Please and thank you! I'm new here, though I've one my research and came up unsuccessful.

--4x4 Multiplier
library ieee;
use ieee.std_logic_1164.all;

entity mult is
port (x,y:IN std_logic_vector (3 downto 0);
        p:OUT std_logic_vector (7 downto 0));
end mult;

architecture mult_beh of mult is

component ha
    port(a,b: IN std_logic;
                c,s: OUT std_logic);
end component;

component fa
    port(a,b,cin: IN std_logic;
                cout,sum: OUT std_logic);
end component;

signal andgate: std_logic_vector(15 downto 0);
signal sumout: std_logic_vector(11 downto 0);
signal carry: std_logic_vector(11 downto 0);
begin
    andgate(0) <= x(0) and y(0);
    andgate(1) <= x(1) and y(0);
    andgate(2) <= x(2) and y(0);
    andgate(3) <= x(3) and y(0);

    andgate(4) <= x(0) and y(1);
    andgate(5) <= x(1) and y(1);
    andgate(6) <= x(2) and y(1);
    andgate(7) <= x(3) and y(1);

    andgate(8) <= x(0) and y(2);
    andgate(9) <= x(1) and y(2);
    andgate(10) <= x(2) and y(2);
    andgate(11) <= x(3) and y(2);

    andgate(12) <= x(0) and y(3);
    andgate(13) <= x(1) and y(3);
    andgate(14) <= x(2) and y(3);
    andgate(15) <= x(3) and y(3);

    --Gates
    ha0: ha port map(s => sumout(0), a => andgate(1), b => andgate(4), c => carry(0));
    fa0: fa port map(sum => sumout(1), a => andgate(2), b => andgate(5), cout => carry(1), cin => carry(0));
    fa1: fa port map(sum => sumout(2), a => andgate(3), b => andgate(6), cout => carry(2), cin => carry(1));
    ha1: ha port map(s => sumout(3), a => carry(2), b => andgate(7), c => carry(3));
    ha2: ha port map(s =>sumout(4), a => sumout(1), b => andgate(8), c => carry(4));
    fa2: fa port map(sum => sumout(5), a => sumout(2), b => andgate(9), cout => carry(5), cin => carry(4));
    fa3: fa port map(sum => sumout(6), a => sumout(3), b => andgate(10), cout => carry(6), cin => carry(5));
    fa4: fa port map(sum => sumout(7), a => carry(3), b => andgate(11), cout => carry(7), cin => carry(6));
    ha3: ha port map(s => sumout(8), a => sumout(5), b => andgate(12), c => carry(8));
    fa5: fa port map(sum => sumout(9), a => sumout(6), b => andgate(13), cout => carry(9), cin => carry(8));
    fa6: fa port map(sum => sumout(10), a => sumout(7), b => andgate(14), cout => carry(10), cin => carry(9));
    fa7: fa port map(sum => sumout(11), a => carry(7), b => andgate(15), cout => carry(11), cin => carry(10));

    --Assigning p values
    p(0) <= andgate(0);
    p(1) <= sumout(0);
    p(2) <= sumout(4);
    p(3) <= sumout(8);
    p(4) <= sumout(9);
    p(5) <= sumout(10);
    p(6) <= sumout(11);
    p(7) <= carry(11);

end mult_beh;


texts:
In my current project setup I have a Li-Ion charger IC (the BQ25890 from TI) which manages the battery charging and discharging process. The charger IC has to power an ATmega328PB. The ATmega in turn controls a MOSFET to a high-current load in the 1-2A area. But most of the time, the ATmega sleeps in power-down mode, drawing only ~200nA of current. Even when it's active, it should not draw more than 0.1mA (+ the 1-2A of course) in average.
To sum it up, a charger IC has to power a device which is always powered but draws minuscule current.

Now there's a problem, and this is why I ask.

I recently noticed a strange behaviour of my power bank, which cuts off current from a device with low current consumption. After reading a bit on the internet, this is not uncommon, and even a well-defined feature: The charger circuitry inside the power bank thinks it's leaking current and therefore cuts any small current off. With that in mind, I carefully checked the BQ25890's datasheet as I don't want such a feature for my MCU. However, I couldn't find nearly anything related to this besides the output voltage. These two values are suspicious:

IBAT(LOAD) - Battery discharge load current - 15mA (min)
ISYS(LOAD) - System discharge load current - 30mA (min)

These values are not further mentioned in the datasheet. If 30mA is the minimum current I have to draw, I would have to power the ATmega from a coin cell. Now these are my questions:

Is my assumption correct the given values specify the minimum output current?
Is my idea of using a coin cell generally better even if I can draw a small current out of the charger IC?

To give you a better understanding, I visualized my circuit configuration:

simulate this circuit – Schematic created using CircuitLab


texts:
I'm trying to wire a 12v DC motor to a DPDT switch so I can control the spin direction (by inverting the polarity) it uses two digital pins, one of them to set the direction of the motor and another one to actually enable or disable the current flow to the motor. The design I came up is this one:

I'm not sure if the relay is wired correctly to achieve the desired functionality


texts:
I'm having a hard time explaining to myself why the output voltage of a buck regulator drops at the load when the load pulls more current than the max limit of the buck regulator.

Can someone help me understand this by assuming let's say I have a 3.3V buck regulator circuit that is rated for up to 2A. What happens to the buck topology components' voltages/currents when the load tries to pull 3A instead that causes the voltage output of regulator to drop?

Does same thing happen if I use a linear regulator instead, meaning output voltage drop during overloading?

Thanks,
Dan


texts: High freq OP-AMP voltage follower is ringing and is unstable

texts:
I try to design analog buffer for the 5MSPS STM32 ADC. I try to use TSH114IDT or CLC4007 opamps ( I need 8 in total). I have done so far:

Tried the design below with or without some of the elements - removing load , output capacitor, input capacitors etc.
Single or dual supply.
Unity gain or gain > 1
Different configuations of the decoupling capacitors

My question:
is it possible to design the stable buffer using those two OP-AMPS?

simulate this circuit – Schematic created using CircuitLab

The best I got:

And the original waveform

another not very successful attempts

Example 1 on YouTube

Example 2 on YouTube

Example 3 on YouTube


texts: What happens if there are many 120 ohms resistors as terminators on the CAN bus?

texts: I connected three devices in parallel on a CAN bus system. Every device has a \$120\,\mathrm{\Omega}\$ resistor built into the circuit. I am using two pairs of twisted cables of \$1.2\,\mathrm{m}\$ each for the communication. Will it have any effect on the communication?


texts: Easiest way to design feedback for boost converter

texts:
I'm trying to design a feedback for a boost converter. When I research on the internet all I get is some really complex control system type stuff that I dont really understand or maybe too advanced for me. I'm not too interested in making it perfect or respond immediately to changes but just a basic feedback.

From what I understand, I need an error op amp with a reference being my desired output voltage which is 30V. I also need a ramp and this ramp is compared with the error and hence generating the square wave.

So how would I set my peak ramp voltage ?, I'm guessing it has to be higher than my reference because at startup the error would be 30-0 = 30V and if the peak is 30V on the ramp then the switch would be constantly on.

I also saw another way using a 555 timer but not sure how that would work

I was currently trying to use a micro-controller with adc as I thought or still think it would be the easiest way. The problem is the output voltage just kept oscillating when I compared the adc result with 30V. Maybe the changes weren't  sensitive enough ?

What do you guys think ?


texts: Delamination or missing gold on PCB pads

texts: Today I received some PCBs I ordered, and they look like they are missing the gold from the ENIG process in some areas.  Am I correct?  What is the cause, and should I be concerned? They seem to still be conductive, but I am worried about in field failures and what I can't see, which is under the solder mask.


texts: Piezoelectric sensor in the disc brake balancing machine shows 50 hz wave when idle. How to remove this noise, I want to get only piezo waveform?

texts:
I'm working on a machine which detects rotational imbalance based on readings from a piezo electric sensor. I have connected piezo with a charge amplifier (op amp based), the output of which shows 50 hz waveform on oscilloscope even if machine is not working. The 3 phase motor in machine is powered via VFD.
 Is there any way to get rid of this noise as I want to see waveform of sensor only?


texts:
I have always assumed that computer keyboards do not, in the typical case, contain integrated circuits. And also, now that I think about it, there must be a set of standard electrical (digital?) signals defined by key that a keyboard sends.

I understand that some fancy keyboards may have their own macro capabilities supported by ICs, but basic keyboards don't use ICs, or?