texts: Oscilloscope/Function Generator with GnuRadio (using very cheap hardware)

texts:
I was just getting started with RF signal processing, and I was very interested in being able to make an oscilloscope and function generator work in real time with python. Essentially, I would like some means of:
*Creating arbitrary waveforms defined by a numpy array (or sending out individual pulses in real time)
*Reading arbitrary waveforms into a numpy array (or receiving instantaneous voltage readings in real time)

I am quite new to this field, and I want to make sure I understand exactly what gnu radio is capable of and how I might go about setting this up.

It seems that gnu-radio is meant to interface with USRP--which is definitely out of my price range at the moment. I want to have a much better idea of what I am doing before I spend more than $20 on this.

I know $20 is not a lot, but I know that I can build an oscilloscope from a $2 usb audio driver, and I can use Mathematica (which I already have) to play arbitrary waveforms through the audio jack in my computer. Radio Shack has all the electronics I need to work with that signal. I am not looking for good sampling rates or anything fancy--yet. I just want a better grasp of the field.

So is gnu radio the best way to go about making a simple oscilloscope + function generator setup?
If so, what is the cheapest hardware I would need to get something that will send/receive arbitrary waveforms?

Added - RM

NumPy:

NumPy is the fundamental package needed for scientific computing with Python. It contains among other things:

a powerful N-dimensional array object
sophisticated (broadcasting) functions
tools for integrating C/C++ and Fortran code
useful linear algebra, Fourier transform, and random number capabilities.
Besides its obvious scientific uses, NumPy can also be used as an efficient multi-dimensional container of generic data.
Arbitrary data-types can be defined.
This allows NumPy to seamlessly and speedily integrate with a wide variety of databases.

NumPy array:

GNU Radio


texts: Magnetometer hard iron / soft iron calibration-compensation

texts:
I have real magnetometer data captured by BMX055. I deployed an hard-soft iron calibration code (magcal) on this data in Matlab. Here is the code:
addpath('quaternion_library'); clear all;close all;clc;load('ExampleData.mat');

%Ideal Magnetometer Data----------------------------------------------------

N = 10000;rng(1);acc = zeros(N,3);av = zeros(N,3);
q = randrot(N,1); % uniformly distributed random rotations
imu = imuSensor('accel-mag');[~,x] = imu(acc,av,q);

scatter3(x(:,1),x(:,2),x(:,3));axis equal;title('Ideal Magnetometer Data');

%Magnetometer Data With a Hard Iron Offset----------------------------------

imu.Magnetometer.ConstantBias = [2 10 40];[~,y] = imu(acc,av,q);
figure;scatter3(y(:,1),y(:,2),y(:,3));axis equal;title('Magnetometer Data With a Hard Iron Offset');

%Magnetometer Data With Hard and Soft Iron Effects--------------------------

nedmf = imu.MagneticField;Rsoft = [2.5 0.3 0.5; 0.3 2 .2; 0.5 0.2 3];
soft = rotateframe(conj(q),rotateframe(q,nedmf)*Rsoft);

for ii=1:numel(q)
    imu.MagneticField = soft(ii,:);
    [~,z(ii,:)] = imu(acc(ii,:),av(ii,:),q(ii));
end

figure;scatter3(z(:,1),z(:,2),z(:,3));axis equal;title('Magnetometer Data With Hard and Soft Iron Effects');

%+ Noise ---------------------------------------------------------------------

imu.Magnetometer.NoiseDensity = 0.08;
for ii=1:numel(q)
    imu.MagneticField = soft(ii,:);
    [~,t(ii,:)] = imu(acc(ii,:),av(ii,:),q(ii));
end

%Magnetometer Calibrated (Hard and Soft Iron Effects Cal)----------------------

[A,b,expMFS]  = magcal(t);xCorrected = (t-b)*A;%r=z-xCorrected;

%Magnetometer Calibrated Plot---------------------------------------------------

figure;scatter3(xCorrected(:,1),xCorrected(:,2),xCorrected(:,3));axis equal;title('Magnetometer Data Calibrated');

%Magnetometer Calibration Residual error
r = sum(xCorrected.^2,2) - expMFS.^2;
E = sqrt(r.'*r./N)./(2*expMFS.^2);
fprintf('Residual error in corrected data : %.2f\n\n',E);

Although Matlab generic data is well calibrated as shown here:
bias-offset-cross axis misalignment of my real data (Magno1.csv) has not been calibrated by the same code:
Why so? I think i got sufficient data, so magcal function should fit its ellipsoid to sphere like in the matlab data. what could be the reason?
Thanks..
p.s.1: Magno1.csv:
https://docs.google.com/spreadsheets/d/1kZVBB7e2zEP52UwmvabkfaAnA7M6ttjVnNGp7hFQcr4/edit#gid=1676163070
p.s.2: For [A,b,expMFS]  = magcal(t), 3x3 A matrices are same for both, only b matrices have different offset values.


texts:
I tried to do a monte carlo analysis of the opamp that I have designed. I ran the simulation for 100 samples with matching and process, suprisingly the results I get are very bizare. I have gains that are not even 1 dB which is something I completely dint see with a normal corner/process variation . I know that the reason for this bizare result is that the simulation takes mismatch into account(shown in image below with the configured simulation).But my main question is how can I improve this result keeping my design as it is ? IS there a way through which I could tune my MOSFET dimensions such that I have imrpoved results ?

Simulation Configuration

Simulation results with mismatch included as shown in the simulation configuration.

Simulation result without mismatch but with only process.

Circuit diagram, with the resistor divider being the outputs from the bandgap reference.


texts: What's a good discharge current for a LiPo battery without a C rating?

texts: I have a raw (unprotected) 3.7v LiPo cell. It's rated 4000mAh. It has the markings "HRDC 14.8wh 3.7V 606090P 20170528". Apparently 606090 is a number commonly associated with this type of battery, but I can't find a datasheet. What's a safe discharge rate?


texts: R65C02P4 (6502) microprocessor R/W pin state while suspended

texts:
I'm building a circuit with a Rockwell R65C02P4. When the RDY line is pulled low, the manual specifies that the address lines will reflect the current address. It doesn't specify what the R/W state will be, nor what the data lines will be.
I am assuming that the data lines will be high impedance (undriven) and that the R/W line will be high.
Is this assumption true?
Here is the clip from the datasheet:


texts:
I was thinking about a circuit which turns itself off:

simulate this circuit – Schematic created using CircuitLab

The push button would bring the positive supply to the microcontroller's VCC. By setting P0, the MOSFET would switch and hold the positive supply on VCC. So releasing the push button wouldn't turn off the microcontroller unless P0 is cleared as well.

Will this work?


texts:
For my project which for the next (many) months I want to make it on a breadboard.

I ordered RJ45 connectors, but these do not fit on a breadboard. What would be a good way (or is there a way) to connect these on a breadboard?

Of course I can solder 8 wires but than still the connector is hanging loose.
Maybe there is a (not necessarily electric solution) how to keep these connectors in place somehow, but I don't have experience in it.


texts: No Voltage on IR21844S HIGH OUTPUT (HO) pin

texts:
I need help, please.
my IR21844S was working when SD (ShutDown active Low) is powered with High logic level  (5V) and Vin with Low logic level  (0V), IR21844S Low Side(LO) = Vcc Voltage and IR21844S High Side(HO) = 0V which "was" Correct. and...
When both SD (ShutDown active Low) and Vin is powered with High Logic level  (5V), IR21844S Low Side(LO) = 0V voltage and IR21844S High Side(HO) = Vcc Voltage which "was" also Correct.
Currently now, when SD (ShutDown active Low) is powered with High logic level  (5V) and Vin with Low logic level  (0V), IR21844S Low Side(LO) = Vcc Voltage and IR21844S High Side(HO) = 0V which is Correct.
But when "both" of the SD (ShutDown active Low) and Vin is powered with High Logic level (5V), IR21844S Low Side(LO) = 0V voltage and IR21844S High Side(HO) = 0.790V - 0.897V according to the Vin PWM signal variation Voltage is not supposed to be.
In a nutshell, IR21844S High Side(HO) is not bringing its voltage anymore when both SD (ShutDown active Low) and Vin is powered with High Logic level  (5V) while IR21844S Low Side(LO) = 0V.
What I noticed I did wrong was that I did not connect the SD(ShutDown active Low) to any Logic Level(High or Low) which I know it shouldn't affect it because it's automatically connected to the GND according to its datasheet Functional Block Diagram but I only connected the Vin to High Logic Level(5V).
secondly, I used a Lead Acid battery 5V 4.5Ah (20hr) as my Logic Level.
logic could be 3.3V or 5V.
The Logic level 5V is meant for the SD(active low) pin so as to Enable the chip to be active and also meant for the Vin(PMW) pin so as to switch the Half-Bridge from its initial position LO = 1 & HO = 0  to  LO = 0 & HO = 1 so that the motor spins clockwise or counterclockwise accordingly to the chip powered.
Now, if the Enable Pin is HIGH (5v) and either PMW1 pin or PMW2 pin is HIGH(with PMW voltage), there should be Movement, right? Yes. which is equivalent to  LO = 0 & HO = 1.
but my own case is different, if the Enable Pin is HIGH (5v) and either PMW1 pin or PMW2 pin is HIGH(with PMW voltage), there will not be Movement. I traced where the problems are then I got to know it was from the Driver High Output(HO) having 0.790V which cannot drive the gate of the transistor and therefore the case is now  LO = 0 & HO = 0.
I hope you'd clearly understand the problems now.
Please Help me out...
Looking forward to your responses.


texts:
I posted a similar question a while ago and got the answer I thought I was looking for but I now have a new multimeter so I'm able to get readings that should be of some use.

I have a solar panel, charge controller and battery. I've left it out for over a week to charge in very good sunlight and the battery hasn't charged. The battery level indicator on the charge controller stays the same. I will try and provide as much info as possible. If someone could point out what is wrong and what I need to do to I'd it, that would be fantastic!

Solar Panel spec:

Pmax - 5W
Vpm - 17.9V
Ipm - 0.28A
Voc - 22.41V
Isc - 0.3A

Battery spec:

Sealed lead-acid
12V
4.5AH
constant voltage charge
Initial current: less than 1.35A
Cycle use: 14.0V-15.0V
Standby use: 13.5V-13.8V

Solar Charge Controller spec:

Voltage: 12V/24V AUTOMATIC
Current: 5A
(That's all that's on the sticker)

When I measure the voltage across the solar panel on its own it gives around 17v when in good sunlight which will charge a 12v battery, right? When I hook up the solar panel and battery to the solar charge controller and measure the voltage across the battery terminals it's around 12.2v and across the solar terminals it's around 12.4v. What's happening? I should probably also point out that when the solar panel is out of the sun and therefore producing less than 12v, the battery terminals still show around 12.2v on the multimeter while the voltage across the solar terminals shows less than 12v. I also don't understand why the load light on the charge controller is always on even when there is no load connected and measuring the voltage across the load terminals, it shows 12v. The voltage across the battery after charging is often around 12.3v but the the next da has returned to around 12.2v

I would appreciate at help.
Thank You


texts: Any way to create a 3 LED chaser with only a 555 IC?

texts: I've seen single and dual blinking circuits, but wanted to know if there was some easy way to squeeze in a third? I don't have a 4017 IC at the moment, unfortunately.


texts: Is it possible to connect a phase control relay to an inverter (VFD)?

texts:
Is it possible to check a motor ON/OFF state by connecting a phase control relay to the inverter and the motor 3 phase terminals?
I have tested a phase monitoring relay to a main 3 phase supply from distribution and the relay works fine but when I connect it to the inverter/motor, it doesn't work. also in one of 6 different possible connection ways, relay get too hot and smoke came out of it! I want to know why? where is my mistake?

*inverter model is: Schneider ATV12H018M2
*phase control relay is: Schneider RM17TG20


texts: How differential amplifiers help reduce noise?

texts:
First off, I'm new to electronics.

Can anyone please explain how differential input reduces noise?

My understanding (please correct me if I'm wrong):
noise usually gets added to the original signal hence increasing it's magnitude, so now if I want to amplify this signal (without the noise) I should provide the same signal to both inputs of a differential amplifier. Since the noise is already added to the original and is present at both terminals, the CMRR should reject signals common to both terminals including noise since it is present in both signals and the output voltage will be zero. Then how should I amplify the signal?

Also even if we have two different input signals, one with noise and one without noise, but same as the other (except noise content), then CMRR should make sure it only amplifies the difference between the two, which is noise. Why would we want to amplify the noise and reject the original signal?


texts:
Something like this:

a=b?c:d ;
would make a=c, if b=1,
else a would be made equal to d;

But what would doing the same thing on an array do?
Like this:

assign a = (|b[10:8])?8'hff : b[7:0];   // to limit the max value to 255
Does it check each of the 3 bits, 8, 9 & 10?


texts:
I try to implement the following simple UART reciever. The simulations goes fine (image attached). But i encountered some problems in real hardware realiztion using Nexys 2 board.
I try to send a symbol through minicom using the following protocol
1 start bit 8 data bits 1 stop bit 115200 baud rate
Also i have 50 Mhz  FPGA clock, which i directly use as UART reciever clk. UART counter count to 434 (F = 115200 Hz -> T = 8680 ns -> T = 20 ns * 434) So checking in 233 we will get the center of recieved bit.
While debugging the output of the uart i attached DATA_OUT from reciever to the Nexys board leds.

It seems to me that i get the wrong symbol codes. For example when i send '1' (00110001) i get 10011001 code
and so on

'2' 00110010  -> 10011010

'3' 00110011  -> 10011011

'4' 00110100  -> 10011000

So my suggestion is that something is wrong with the VHDL code, but i don't understand what exactly... Can anybody help me please? Thanks.

entity uart_reciever is
    Port ( clk : in  STD_LOGIC;
           rx : in  STD_LOGIC;
    recieved : out std_logic;
              en : in  STD_LOGIC;
           data_out : out  STD_LOGIC_VECTOR (7 downto 0)
              );
end uart_reciever;

architecture Behavioral of uart_reciever is
    signal count : std_logic;
    signal rec : std_logic := '0';
    signal counter : integer range 0 to 433;
begin
    process (clk)
        variable state : integer range 0 to 9 := 0;
        variable data : std_logic_vector (7 downto 0);
        variable rx_p : std_logic;
        begin
            recieved <= rec;
            if rising_edge(clk) AND en = '1' then

                if (rx_p = '1' and rx = '0') then       --
                    count <= '1';
                    rx_p := rx;
                else
                    rx_p := rx;
                end if;

            if (counter = 216) then
                rec <= '0';
                case (state) is
                    when 0 =>
                        if (rx = '0') then      --  -
                            state := 1;
                   else
                            state := 0;
                     count <= '0';
                   end if;
                    when 1 =>
                        data(0) := rx;        --
                  state := 2;
                    when 2 =>
                        data(1) := rx;
                  state := 3;
                    when 3 =>
                        data(2) := rx;
                  state := 4;
                    when 4 =>
                        data(3) := rx;
                  state := 5;
                    when 5 =>
                        data(4) := rx;
                  state := 6;
                    when 6 =>
                        data(5) := rx;
                  state := 7;
                    when 7 =>
                        data(6) := rx;
                  state := 8;
                    when 8 =>
                        data(7) := rx;
                  state := 9;
                    when 9 =>
                        state := 0;
                  count <= '0';
                        if (rx = '1') then
                            data_out <= data;
                            rec <= '1';
                        end if;
                end case;
            end if;
        end if;
    end process;

    process (clk)
    begin
        if rising_edge(clk) then
        if (count = '1') AND (counter < 434) then
                counter <= counter + 1;
        else
                counter <= 0;
        end if;
        end if;
end process;


texts: Solar controller with BJT transistor and PIC24 microcontroller to charge 3.6V NiMH batteries

texts:
I'm designing a solar controller circuit and am having some confusion about how to switch the BJT on and off. I have a single solar panel charging a battery. The BJT is there to prevent over-charging the battery. I have a microcontroller to monitor the battery voltage and current, and use this feedback to switch the transistor off and on. The microcontroller is powered by those same batteries.

Here's a simplified circuit schematic:

simulate this circuit – Schematic created using CircuitLab

Do I need to figure out the collector current (I_C drawn from the solar panel) based on the current coming out of the microcontroller (I_B)? Or vice versa?

I'm not sure which comes first. I know that I_B is what turns the transistor on and off to allow I_C through.. but I'm confused how to get values for each.

Here's the data on the components:
The solar panel typically outputs 5.5V and 170 mA. It has an open-circuit voltage of 8.2 V and a maximum load voltage of 6.4V. (linked here)

The batteries are rechargeable NiMH with 2450 mAh and 3.6 V. (datasheet here)

The microcontroller is the PIC24, which can source up to 25 mA through its I/O port. (datasheet here)

Here's what I'm stuck on:

Typical solar values:
V_solar = 5.5 V
I_solar = 170 mA

Values for beta, base current, and base-emitter voltage:
B=100
I_B = 1 mA (from microcontroller datasheet?)
V_BE = .7 V

B*I_B = I_C
100 * 1 mA = 100 mA

I_B = (1.6 - .7) / R = 1 mA
R = .9 V / 1 mA = 900 ohms
Since I_B > 1 mA, R > 900 ohms = 1k ohm

I obtained I_B from the PIC24 datasheet, where it says output high from an I/O pin is at least 1.6 V when the PIC24 is powered by 2 V, and the current associated with these numbers is 1mA. Is this the correct way to obtain these values from the datasheet?

Revised Circuit (2/10/15):

simulate this circuit


texts:
So there is this weird hole on top of the earth pin of an appliance:

I dont know whether this is normal or not, or whether it's safe to use or not. Should I repair it, or use it hoping that nothing would go wrong?


texts:
I am looking for a way to get my phone to output a TTL level signal, up to about 1200 baud. Any suggestions?

The only thing I can think of is using an audio output with a square wave signal, and then amplifying it. Is that workable? Anything better?


texts:
I have a pair of questions. It is a class exercise where I am asked to calculate the average power of the elements and the average power supplied.

The first question: The sources are expressed in polar numbers and think I can not see their sine formulas, however, at the end they are real numbers, are they in direct current?

The second question: With a voltage source and a current source, can I analyze them together? I think in this case I need to use the principle of superposition.


texts: Fourier coefficients of a double frequency signal

texts:
I have a doubt regarding the fourier coefficients of a signal. I have a signal generator of sin(wt). After a single phase bridge rectifier of 4 diodes, I obtain in the output a signal equal to abs(sin(x)). As this signal is even, I know that bn coefficients of the Fourier Series decomposition will be zero. Anyway, I don't know what I should do to obtain the fundamental harmonic (in this case a2, as the frequency is twice in the output). I have two options, but I don't know which one, if any, is the valid one:

1) The first way I find to obtain it is by applying the definition, and separating the absolute value of the sine in two parts, obtaining:
$$\frac{2}{2\pi}[\int_0^\pi sin wt *cos 2wt dw - \int_{\pi}^{2\pi} sin wt *cos 2wt dw]$$

2) As the frequency in the output is the double, compute the following:
 $$\frac{2}{\pi}\int_0^\pi sin wt *cos 4wt dw$$
Considering that now the expression would impy $$cos(2nwt)$$ due to the double frequency in the output.

Which one would be the valid one? Any help is appreciated!


texts: e13007f npn transistor datasheet reading for turn on time

texts:
I am reading datasheet for e13007. You can get it here: http://www.datasheet-pdf.com/datasheetdownload.php?id=520587
(click on "Download PDF for PC")

In "Electrical Characteristics" section under turn on time it says 1.6 us (max value). Now in the figure 4.(on page 2), I cant read this of the graph!
Curvers are for tr and td. I know that tr+td=turn_on_time. Reading the graph (for Ic=5A) I get
555us for turn on time. What am I doing wrong? Or what is turn on time for Ic=5A (one from the table or one from the graph or something else) ?


texts: Why were bipolar junction transistors (BJTs) better than metal oxide semiconductor field effect transistors (MOSFETs) in the past?

texts:
I know that MOSFETs are used much more in industry than BJTs at the present, but I heard that performance of BJTs was better than that of MOSFETs in the past.
Can you tell me why?
Additionally, where are BJTs still used?


texts:
I'm trying to integrate a breakout board circuit from SparkFun into my own design. It uses an external coax antenna with a SMA connector. I've brought their circuit over in its entirety, and from a hookup standpoint, it's identical. I'm worried about routing the antenna input to the GPS chip in my circuit though, as I have servos on the same board. Are there any rules of thumb to follow here? It'll be hard to see, but here's a picture of the layout, with the current GPS line highlighted:

GPS datasheet: http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Sensors/GPS/Venus/638/doc/Venus638FLPx_DS_v07.pdf


texts: Will an impedance matching network also act as a filter?

texts: Will a matching impedance network also act as a filter? I'm using a pi network and am wondering if I should also add a filter. I designed the pi network by using the program SimSmith and it consists of a shunt capacitor, series inductor, and another shunt capacitor.


texts:
I'm building a grinder, which consists of a shaft on which the grinding wheels sit, and the shaft is driven by a universal motor out of a washing machine via a belt and a pulley.
I'm using an off-the-shelf SCR speed controller.  What I'm finding on the first test run is that the motor slows down a lot when I, e.g., try to sharpen a chisel on the grinding wheel.  I can turn the knob on the speed controller up to get it up to the speed I want while sharpening, but then as soon as I take the chisel away, the motor starts to spin up and I have to turn the speed controller down to stop it spinning out of control.
I realise that this is probably the expected behaviour for such a motor, and you may very well tell me that I'm using the wrong motor for the job, and that a motor such as those in my bandsaw, sander, and drill press is what I need (I don't know what that type of motor is called).  But this is what I have, and I like using things that I have already, unless it really turns out to be too complicated.
So, is there a simple (or less simple, but not ridiculously complicated) way to make the motor run at a more or less constant speed regardless of the load?  I'm open to mechanical or electronic solutions (the motor has a tacho coil), either off-the-shelf or DIY.
Many thanks!


texts: How can I tell if an RF transmitter is transmitting?

texts: In my project, I use a use an RF Transmitter and Receiver. One of the RF components seemed to fail because the connection between my Arduinos no longer works. I cannot determine whether the RF Receiver or Transmitter works. I want to see if my RF Transmitter gives an output, but I do not own an oscilloscope to view it's waves. I've seen this answer, but it only shows if the Arduino is sending data to the RF Transmitter. Is there any alternative way to check if the RF Transmitter works or not? Thanks!


texts: I'm using a 22u 6.3V X5R 0805 ceramic capacitor to filter out a 3.3V supply (for a buck converter.) I've heard that applied voltage has an effect on the capacitance of certain ceramic caps; a higher voltage causes a reduction in capacitance. How true is this? Would it decrease too much as to not work as a suitable filter cap? I think 10-15u is probably the minimum for it to remain stable, although the ripple will probably increase at lower capacitance. Any ideas?


texts: Beginner, Confused as to how to solder a "Y Split" Molex Connector to a USB

texts:
I am currently working on a project in which two small computer fans are powered from a USB port. I want to be able to get two laptop fans powered off of one USB slot.

I was looking into some solutions, and I found a power cord that matches exactly what I want to do. The thing I am confused is that when the power cable is split, the cables  double at the point it splits, which is also the point in which I want to solder to the USB wire.
.

The problem I face is that the USB only has 4 single free cables , not two cables on top of each other in each pin slot like where the Y split Molex cable above, so I can confused as to how I would attach it to the USB if there is one more cable on all slots? Are the cables attached at the end by one of those Molex pins, and then I just solder the pins to the exposed USB wire?

Furthermore, there are two black wires in seperate pins on the Split Molex cable, which one would I solder to the USB, as I know the only red cable would be soldered to the only red cable on the usb.

In comments: How would I solder the Molex connector to a USB if the molex connector has 2 wires seperated into 4 sections (as the USB cable only has one wire separated into 4 sections). If you look at my last picture, would I just solder those metal pins directly to the exposed wire on the usb, or would I chop those pins off, solder the two wires on the molex together, then solder the now combined wires to the usb wire?


texts: Using of matrices in simulink block diagrams

texts:
All simulations I've done in simulink as yet have not matrix in their block diagram like the following picture :

and they have block diagram structure like :

for simulating a system that has matrices with variable parameters in matrice ,in its structrue, how can use matrices as block diagram in it?
for example for following system:

I can't set and adapt the dimesnsion of blocks.


texts: Replace USB diode with something else to reduce voltage drop

texts:
So I've made this circuit with a MOSFET and an Op Amp to select a voltage input to my battery. I sort of based it off the voltage selector circuit on the Arduino Uno board, but inversed since that defaults to the barrel plug, but I want to default to USB.
I like it, but that diode creating voltage-drop across the USB input is slightly bothersome and reduces the USB voltage to 4.49V. Is there any way to remove the diode from this circuit and replace it with something else (ex. a MOSFET)? I couldn't figure out how.
The first MOSFET at DC In is for reverse voltage protection, while the second is for switching inputs.
Here's the part numbers in case you happen to want to look at the datasheets:

P-MOSFET: AOSS21311C
OP Amp: LM321SN3T1G

EDIT: Second question: I think the fact that the voltages at the inputs are below VSS relative to the Op Amp might damage it, am I right about that? In which case I'd have to redesign the circuit somehow. I'm not even sure they make P MOSFETS with a Vgs that goes up to 30V, I couldn't find a single one.


texts: Will crosstalk be induced if signal running in parrallel to power trace?

texts:
I haven't come across any mentions of signals running in parallel with power traces. Everyt mention thus far has been two signals to each other.

If I have a low amplitude signal (sinusoid < 10khz) (10 mil trace), lets just say its 1V, and its running in parallel (10 mils) with a 5V power trace (30 mils) and there is an ground plane directly below. What happens to my signal ? What happens to my power ?

A few scenarios

Power trace feeds IC's directly
Power trace feeds decoupling caps directly which were chosen as the typical 100nF value.
Power traces feed decoupling caps directly which were chosen to have the largest capacitance possible for its footprint ? (This can be anything you feel is realistic)
Power trace feeds local reservoir caps and each reservoir cap distributes its power for a particular region of the board. All the components within that area have decoupling caps being fed from their local reservoir.

The order of the scenarios should be that would cause the power trace to go from most demanding to least demanding.

Edit

Added signal type - its a sinsusoid


texts: Relative propagation delay matching instead of length matching in PCB design?

texts: Why do we need to use relative propagation delay matching instead of length matching in PCB design?


texts: Directly connecting a transceiver and DAC

texts: I have an application where I need to take data over a standard transceiver (such as shown here: https://ii-vi.com/product/100g-cwdm4-2km-gen3-qsfp28-optical-transceiver/) and have that data drive a high-speed DAC (such as the one shown here: https://www.ti.com/product/DAC38RF82#design-development). How should I go about trying to have these two devices talk to each other? Any ideas would be greatly appreciated.


texts: How to get ADC input with high resistance?

texts:
EDIT: Original post was phrased as XY problem.

What I need to do: Determine if power at "Switched power" is being turned on by SW1/FET combination or other power sources not pictured in the diagram below (there are multiple sources). My first thought was to sample the voltage on the switch line - if it is pulled low, the FET is turning on the power.  If it is high, it is not.

Original post:

I'm trying to determine how to measure the voltage V? in the below circuit.  It is a high-side switched power circuit using a P-channel FET that is off when SW1 is open.

simulate this circuit – Schematic created using CircuitLab

However, I'm balancing a few competing problems:

1) Resistance into the ADC is too high.  By my measure I'd need to keep the sample frequency <100k per second to get a value (computed from answer to Protection of ADC inputs) but the sample rate is 2 Msps on the processor.

2) I can't decrease R1 enough to fix #1 or the voltage V? will drop too much, possibly turning on the FET or putting it into a partially conducting state with high resistance (aka bad).

3) I can't decrease Rfet or it will pass too much current when SW1 is closed.

Note I don't really need an accurate measurement here, I just need to determine if it's GND or some other voltage value.  Aka on or off.

Is there a better way to go about this?  I saw mention of possibly using an op amp at the sample point..  Obviously the fewer components the better but whatever is required is required.


texts:
am designing a BLDC hub motor (48V-500W-15A max)

I have designed a three phase inverter and the motor run normally with smooth rotation and as the motor start running and I apply the load the motor draw more current and every thing is normal.I am using PWM to control the speed

But the problem is that as I apply a load before the motor start to move even a very small load the motor do not start till we reach a high PWM value then the motor draw a very high current spike it reached a 26A then the motor start rotating at a fairly high speed. we run at 10KHz frequency.

So is there is an issue should I take care with at starting the motor on a load or this is a nature response and The only solution is to use very high rating components,,,


texts:
Why is there voltage drop across resistors?

Characteristic impedance is the ratio between voltage and current in a transmission line, but resistors also have impedance that translates to voltage drop. Why does power dissipate across a resistor? And how can a transmission line be lossless?


texts: How does a USB 2.0 Wall Charger negotiate current output?

texts:
I'm trying to use a mobile phone charger for my projects, and want a high current output. I have read this, however my measurements show something else.
Here is a link to the Battery Charging Specification Rev. 1.2.

1.4.7 Dedicated Charging Port
A Dedicated Charging Port (DCP) is a downstream port on a device that
outputs power through a USB connector, but is not capable of
enumerating a downstream device. A DCP shall source \$I_{DCP}\$ at an average
voltage of \$V_{CHG}\$. A DCP shall short the D+ line to the D- line.

I verified on three different chargers, and all read \$R_{DCP\_DAT}\$ as ~1.5 Ohms. Now, if there is a short between the D+ and D-, there is no detection on the charging port side, and the charger should always output \$I_{DCP}\$ {0.5 - 5.0A max} on the VBUS line - is this correct?
I tested the current output of three chargers, but they are all completely different.
Charger 1 - Nokia
Rated current output: 1.3A
Measured current output: 1.34A
Charger 2 - Asus
Rated current output: 2.0A
Measured current output: 0.7A - 1.1A (unstable)
Charger 3 - HTC
Rated current output: 1A
Measurent current output: 0.1A
If all these dedicated charging ports have no current negotiation, how come only one charger is showing it's rated output?
N.B All three chargers can charge a mobile phone in a reasonable amount of time.


texts: driving high and low side mosfet for synchronous buck converter?

texts:
I am designing an MPPT charge controller. I have chosen my MOSFETs to be both NMOS https://www.sparkfun.com/products/10213 (FQP30N06L) 60V, 30A. Since the gate voltage is 3 to 5V. I can drive the low side, however, how can drive the high side? since \$V_g\$ should be higher than \$V_s\$, which in this case is \$V_{in}\$ (around 37 V). A lot of people say using a half bridge driver. But also there is a problem. The output voltage is present always (battery voltage), which causes a problem for the driver.

input voltage is 5-37V and I max is 9A
the shared node is Dutycycle*Vin during Ton and it is 0.7V during toff

Any suggestions?


texts: if we use a motor( Nema 17) instead of a resistor as a load, how do we know how much current is it drawing? ( if it is hooked up to a power supply of 12V)


texts: Wien bridge oscillator - what is a suitable replacement for the "bulb" typically denoted?

texts:
The Wien bridge oscillator is usually denoted with a bulb to balance the gain of the system and produce stable oscillations.

Unfortunately, I don't have any bulbs, so I'm curious what a good modern replacement is, and how one would design such a replacement.


texts: Is there any special reason behind the formula of radix complements? My concern is with whether memorizing the formula is the only way to remember it

texts:
I am recently studying the concepts of diminished radix complement and radix complement. This is a simple question. I am aware of the formulas. I just want to know if there is a special reasoning behind why they are made that way. Yes, they are used to represent negative numbers and perform logical operations but when it comes to learning I kind of remember things better if they have some sort of associated reason why formulas are constructed that way. But I do fully understand if there is no derivation and the concept was made out of convenience.
Yes I also know the formula is short. I am just asking out of curiosity.
The formula I am referring to is
r's Complement
r's C = r^n - N
(r - 1)'s Complement
(r - 1)'s C = r^n - r^-m - N
r - radix
n - number of digits
m - fractional part
N - original digit


texts:
I've put together a toroidal transformer using a core suitable for 1500VA. The primary coil is around 70 turns with the secondary coil being just one. When I plug it into the mains (110VAC), I just get a second of humming and the circuit breaker goes.

I'm guessing I'm missing something obvious but how do I stop the current from building up to the point it overloads.  I'd like to keep it at 1kw continuous.

I've watched a number of YouTube videos, can't see what I'm doing differently.

Saturation flux density is 20350 gauss.


texts: VGA Output for 640 x 360 (16:9) Display for LCD monitor

texts:
I'm currently designing a TTL-based device to output VGA signals to a 16:9 aspect ratio LCD Monitor with a frame rate of 60 Hz. I hove mostly been referring to this question on how the VGA protocol functions.

I want to be able to calculate how many micro-seconds the H-SYNC and V-SYNC pulses are for 640x360 @ 60 Hz refresh rate. Is their a formula or a table I can refer to to predict the length of the sync pulses?


texts: I have come across a chip which is only available in LGA. I wouldn't touch BGA, but what about LGA? How possible is it to design for one with little experience? Are there any gotchas? I'm planning to reflow solder these using a hot plate.


texts: (Layout Plus 9.2) How to copy a part from one MAX file to another

texts:
I have a Layout Plus 9.2 file.
I want to copy some components on it to another file (I don't have component library).
How can I export those components to a new library?
How can I copy them to a new Layout Plus file?


texts: How can I build BJT amplifier with Vin and Vout requirements (peak to peak values)

texts:
I have been working on a project but I'm not sure if I'm complying with the requirements that I was given.

Design a BJT amplifier such that VIN=0.1 V and VOUT=5 V (peak to peak values). Justify the gain of the amplifier by performing DC and AC analyses for the design.
Increase the value of VIN in order to reach the saturation point in the DC load line. Justify the value obtained experimentally using the theoretical analysis of the Q-point.

Here is a screenshot of the BJT amp I have done in iCircuit. I adjusted the values until I was able to get a 5 V output but I'm not sure if my circuit meets the requirements. Can anyone help me with this project?

Here are the images of the diagram Joink Suggested. When it initial y displays a 5 V P-P value and then it switches to alternate current with a peak to peak value of 107mV

But the output volate is 5 Peak to peak from the capacitor as you suggested in my opinion.
5 P-P

Then it displays the following


texts: Short Circuit Scenario to understand short circuits

texts:
I am trying to describe the best I can the scenario I came up with in order to try to understand a short circuit.

Let’s say there is only one main circuit breaker and there are two outlets in the room.

Let’s say that outlet 1 gets short circuited by a cable that is cut on an Air conditioning unit.

Outlet two has a gfci type circuit breaker or a detachable circuit breaker with extra outlets ( An outlet extender with a circuit breaker)

Now to my understanding when a short circuit happens there is high amperage flowing through the circuit until the main circuit breaker pops and shuts off the power.

Now in those milliseconds of time between the short circuit happening and the circuit breaker popping, theoretically there is ALOT of amperage going around on the main circuit until the main circuit breaker pops.

This includes the excess amperage traveling through outlet 2. Theoretically shouldn’t the outlet with the circuit breaker pop as well as the main breaker since it is experiencing the flowing of extra amperage as well and by turning off  and cutting electricity from outlet 2 help the devices that could be connected to it not get their power supplies / components damaged since it is closer.

Even if it does not pop should it not help since it is isolating a sub circuit from the main circuit that is experiencing the extra amperage.


texts: How to program the flash of multiple PIC controller

texts:
We have 6 dsPIC33F (16bit) controllers in the system and the system is quite big and complicated. All controllers are located on different PCBs and connected to each other through RS485 bus.

First Pic controller (Master) is connected to PC and the rest of the controllers (5 slaves) are connected to Master using RS485 bus.
To program master dsPIC uses MPLAB-ICD programmer connected to PC.
Now To program Slave1 dsPIC we have to open the machine then locate the PCB and connect the programmer manually then program it.
Similarly we follow the same procedure one by one for all controller by removing the programmer and connecting to respective PCB to program the dsPIC.

I want to program all the controllers through software one by one from PC without removing the MPLAB_ICD when it is connected between the Master and PC by default. Or is there any other method through hardware or software to program all controllers one by one from PC itself without doing it manually?

What hardware/software changes do I have to make to program the dsPIC without opening the system?


texts: Drive a 3w led with a 18650 li-on battery

texts:
I'm getting crazy trying to figure out if there is any easy way to power up a SINGLE 3w led  3w - Forward Voltage: DC 3.2-3.4V - Forward Current: 500-700mA
 with a single 18650 li-on battery

Minimum Capacity: 2250mAh (0.54A discharge at 20°C)
Typical Capacity: 2100mAh (0.54A discharge at 20°C)
Nominal Voltage: 3.6V
Discharge End Voltage: 2.5V
Standard Charging Current: 1.1A
Charging Voltage: 4.20±0.03V
Standard Charging Time: 4.0hours
Max. Continuous Discharging Current: 2.2A
Internal Resistance: less than 35mΩ
Weight: less than 47.0g

Is there anyway to do it without using a dc-dc buck converter?
I'm trying to change a led on a torch, so I have not so much space to work in.

Thanks


texts: How to create a symbol in EAGLE that consists of multiple other symbols?

texts:
I'm trying to create a symbol that consists of multiple other symbols. I'd like it to look similar to what's in this datasheet.

I have found out how to create the part itself, but i'm not sure if I can use the MOSFET symbols combined with diode symbols to create the symbol for this part. Any assistance is greatly appreciated.

Thanks!


texts: Why do rechargeable batteries show different voltages?

texts:
I'm using two of the following rechargeable batteries http://www.renata.com/fileadmin/downloads/productsheets/lithium_polymer/ICP501233PA.pdf in a parallel configuration to power up a small development board that reads data from different sensors and saves it on an sd card.

The device works for around 10 hours and then turns off (battery drained). Recharged for a couple of hours and again measurement.

I've measured the voltage (on the board, so with both batteries connected in parallel) and usually it shows 4.1V (fully charged) and above 3V after discharge.
Still, I've also noticed that some of the batteries show voltages between 1.7V and 2.1V after working ok for 10 or more hours (also measured in parallel).

I assumed that the protection circuit is defect and tried to replace the batteries.

My issue is that if I measure the voltage on the disconnected battery, the value is again 4.x V. (measured together in parallel OR each separately)

Can anyone explain me this ?

Are the batteries broken or the protection circuit is broken or it just needs a hard reset ?

Note 1: The batteries are soldered on the board and never disconnected.

Note 2: The batteries have already more than 300 charge/discharge cycles.

Thank you.

(Pretty specific question but I need to understand what's happening)

Note 3: The firmware installed on the boards on which I've measured the unusually low voltages doesn't start anymore. I've disconnected the battery and soldered back, the voltage is again 4.0x volts and everything seems fine.
Having several boards in use, I am still concerned that it will fail again.


texts: Simple voltage regulator - problem with low temperature

texts:
I've a problem with the attached voltage regulator. It works fine at a room temperature, but when the ambient temperature drops so is the output voltage.

What is the reason for that? Is there a way to fix the problem?

Update-1 The output voltage is set at 3.3V @ 25degC, but drops to 1.9V at -5 degC.

Disclaimer I haven’t designed the circuit, so I'm not aware why certain design decisions were made. I'm not an expert electronics engineer, typically I program the damn device ;). However I'd really like to fix that one with your help.

Solution As adviced I've replaced Q11 and Q12 with a pair of BC847 transistors and it works fine now.


texts: Difference between Bidirectional TVS diode symbols

texts:
I am intending to use this CDSOT23-T05C Bidirectional TVS diode in my design to protect two separate data lines, however the symbols in the datasheet are contradicting conventional rules.

This is how two different packages of this TVS diode family are shown in the datasheet.

and this is how I normally have seen bi/unidirectional TVS diodes

I really doubt this is a type however, I have a remote guess that I might actually need to use two of these bidirectional packages to protect two lines by ditching the 3rd foot and use 1st to connect to the data line and 2nd to the ground rather than how the NUP2105L example is shown in the second figure.

So the main question is: Can I use a single CDSOT23-T05C (bidirectional) TVS diode to protect two data lines similar to how the NUP2105L example is demonstrated in the second figure?


texts:
I am experimenting with the circuit for an Arduino high side driver from Nick Gammon:

I need the circuit to work with a voltage range from 22V up to 30V and ideally stay cold.
Everything else is fine, the MOSFET handles high currents without problem, but my problem is with the npn-transistor - it just gets extreme hot, especially at 30V. I am using 2N2222.

Can the circuit be adjusted in such a way that there will be no need of heat sinks or more powerful elements?

EDIT: After the suggestions of @Nick and @Edgar I changed R1 with 1.2K and R2 with 4.7k. Now the circuit is running for ~45 min without a problem, and is much cooler, I can even touch the transistor :)

I maybe had to better explain what I meant by 'extreme hot' - after a couple of minutes the thermal shutdown kicked in. That hot.

I am also considering switching to MOSFET-only solution, based on Figure 3 site 2 in this application note from Vishay:

Setting the divider to 4.7k/15k should give me less than 2mA through the N-MOSFET (according to TINA I made it and it works like a charm!) so this should be even more cooler. It also should be able to handle even higher voltages without the zener, but I suppose it doesn't hurt to leave it as a surge protection.


texts: Altering switching power supply schematic to generate 5v instead of 3.3v at 5A

texts:
Im fairly new to this level of more complex circuit design so forgive me if I sound like a newb.

I'm creating a DC/DC Step down buck regulator using the LM22678 switcher from texas instruments: http://www.ti.com/product/LM22678

The documentation depicts an application of the switcher for an output of 3.3v at 5A.

The documentation is rather complicated for someone who is not an expert. What values of the capacitors, resistance and inductance would I have to modify in order to generate a 5-6v output at 5A?

Below is just a start point of my design on eagle:

EDIT:


texts: How to deal with an inconsistent / noisy power signal?

texts:
I'm using a 12v power supply to operate a system of sensors that is very sensitive to fluctuations in the voltage input. Unfortunately, I can't control what goes on upstream of my components and this is causing a few issues:

1) On occasion the voltage will dip or spike to levels that are outside my usable range (I've observed fluctuation from 10.5v to 13.5v). The change doesn't last long, but it's enough to mess with my electronics.

2) Additionally, the power line seems to pick up a not-insignificant amount of low voltage interference (EMI?) that I can't control wholly via software.

To that end, I would like to introduce a regulator/filter to control my input voltage - keeping it as close to 12v as possible and eliminating the outside interference. I don't have a lot of space to build up a whole new circuit or introduce custom components, so I'm trying to use as many off-the-shelf parts as possible.

My thoughts:

A) I've used buck converters in the past, and I'm familiar with the operation of boost converters. Could I use a buck converter (dirty 12v -> 5v) and then a boost converter (5v -> clean 12v) to deal with the large fluctuations? I'm also trying to keep the current draw in mind as the power supply has a 10amp fuse in my circuit. What kind of impact would this have on the available current? On heat dissipation in a closed environment? One of the reasons I'm leaning toward this is because I may have need of a clean 5v power line later, and this takes care of the conversion.

B) Could I ground out some of the noise with a dc power-line filter? I haven't been able to identify the source of the noise, so I'm hoping to go as broad as possible - would a filter to reduce common and differential mode noise be a good start or should I investigate other options?

I know that my points are rather vague - I'm still in the early stages of putting my sensor system requirements together, and I'd like to protect against as much as possible now, while I still have easy access to the raw power line.

Any advice / direction is greatly appreciated!


texts: Getting MSP430 USB Driver Signed By Microsoft

texts:
I am developing a product which utilizes an MSP430 microcontroller with a built-in USB module. I obtained a PID from Texas Instruments and used their tools to generate the descriptors, as well as a .inf file to install the driver software. The obvious issue is that due to the custom nature of these files, a popup is presented (on Windows 7) upon plugging in the USB cable that warns the user that the driver is not signed. I believe on Windows 8 and Windows 10 it simply blocks it and does not indicate this to the user at all.

As this is a full-featured product which my company is planning to release, we need to obtain a driver certificate (I believe in the form of a .cat file?) that we can provide to the customer so that they can install the device driver software without issue.

I have been through quite a bit of the Microsoft documentation (most notably this document) trying to get a grasp of what is required in order to get a driver signed, but unfortunately this is over my head at the moment.

This is what I think I understand so far:

I need to submit my driver (.inf file?) to a Microsoft-authorized certificate authority (CA). There are a number of these out there, so I would need to find one that signs drivers.
After selecting a CA, generally I will need to pay an annual fee (most commonly for 1, 2, or 3 years) for their service. Any drivers I generate during this time will be permanently signed, even after the service expires. If I want to change the driver or create a new one after the service has expired, I will need to buy service for another 1, 2, or 3 years.
After paying the fee, the CA will generate a .cat file which is a certificate assuring that the driver I gave them will not be changed. If it does it will no longer match the .cat file and an error will appear during installation

Is this correct? At the risk of sounding like I'm seeking recommendations for specific CAs (I'm not, mind you), where can I find a list of CAs that are able to do this certification for me? Even better would be their websites and/or prices for different service durations. Has anyone here had direct experience getting a driver for a USB microcontroller-based product signed by a CA, who would be able to help me understand and get through the process? I have already posted to the MSDN forums but it seems pretty dead there - It's been two days and my thread only has a handful of views.


texts: Determine the operating voltage of a SIM card

texts:
I'm trying to get my SmartCard reader to communicate with my phone's SIM card. I have a level shifter to drive 1.8V and 3.0V SIM cards, but the Wikipedia article specifies that there are also 5.0V SIM card. I just want to be sure that my SIM card is not a 5.0V one.

How can I determine the operating voltage of my SIM card? (I have access to a scope, and my SIM card is a Tesco Mobile one produced by Gemplus.)


texts: How do I calculate the illuminance of a laser beam?

texts: Does anyone know the equation for this? I am trying to calculate the illuminance of a laser beam. I am shining a laser onto a solar cell. The solar cell's datasheet has graphs with illuminance (lux) and I am trying to convert watts to lux.


texts:
How would I amend a 12V fan to take 2*5V?

The 12V fan has 2 wires on it. one would take 12V the other GND.

I'd like to be able to feed it  5V and 5V, instead of just 12V.

What do I need to do it?

I'm a geek but not an electronics geek..so if there is terminology, please use it but tell me what it means..


texts: How do I use a 4-bit Adder, 4-1 MUX, and 2-1 MUX to implement various micro-operations on registers?

texts:
One of the exercises in my Logic Design coursebook requires me to create a circuit that handles following micro-operations on 4-bit registers R1 and R2.

R1 + R2
R1 - R2
R2 – R1
R1 – 1
-(R1 + 1)
0
-1

However, the constraints are that I can only use a 4-bit adder, 4 to 1 MUX, and 2 to 1 MUX in the procedure of doing so. I have tried various configurations but I cannot wrap my head around it.

Edit: Register storage is not required.


texts: How do I make pads for "spades" on my PCB in Eagle?

texts:
I've seen many devices with spade-like connectors (DC Jacks, AV connectors, etc.) such as below:

The datasheet for the above connector has the follow pad layout:

However, there is no drill hole / line cutout on the pads. Is there a way in Eagle to specify a line cutout rather than a drill hole so the board house knows what to do?

Making drill holes makes it very hard for the solder to adhere onto the connector, because there are huge semi-circle gaps around the flat connector.


texts: How to create a 100ms delay between button pressed and line grounded?

texts: I have a line pulled to +5V. When a button is pressed, it should ground the line after a 100ms delay. How would I implement such a delay?


texts:
I am currently designing a Flyback-based offline AC/DC converter similar to the following schematic (with a few changes e.g. sync rectifier at the output). Everything works nicely but the custom-made transformer is slightly "overheating" (~75°C) at full load (12V - 39W). Since this device will be used in a container where convective cooling is rather limited and the external ambient temperature can reach up to 60°C, the goal is to keep the temperature rise as low as possible.

After double checking, the temperature rise is indeed coming from the transformer itself rather than the peripheral components.

I am aware that a transformer can suffer from overheating e.g. if it is over-driven / saturated, however, it does not seem to be the case here.

Transformer main parameters:

\$L_P=320\mu H\$
\$L_{P(leak)}\approx 6\mu H\$
\$N_{PS}=6.6\$
\$R_{P}=414m\Omega\$
\$R_{S}=13m\Omega\$
\$I_{OUT}=4A\$

System parameters:

Supply Voltage: \$90VAC-264VAC\$

The questions I have are the following:

Can you say that the above temperature is really excessive for this operating condition (12V@39W)?
Are there any other possible reasons why it would heat up considerably?
Provided that the peripheral components are kept cool (e.g. RCD Snubber), can they affect at all the thermal aspect of the transformer?
What mechanism could possibly cause the losses in a transformer to increase at a higher supply voltage? I was expecting it to be larger at a lower supply voltage, due to the higher primary's current.

Since the question revolves mostly around the reasons why a transformer in such a topology would heat up, I decided to keep the details out.

EDIT#1

Below are two measurements for \$90VAC\$ and \$264VAc\$ respectively, with both the \$V_{DS}\$(orange) of the primary's mosfet and its current sense voltage drop \$V_{CS}=I_{CS}\cdot 200m\Omega\$ (blue).

Due to technical limitations, the whole switching amplitude range could not be displayed in the osci for the higher supply voltage.

I appreciate any feedback.

Thanks.


texts:
I successfully opened the battery of my laptop without damaging the case, and now, I want to replace the worn out batteries (2600mAh) with more powerful ones (3200mAh).

I know the risks of working with lithium batteries. I'm an electronics engineer, but I don't know if the integrated circuit of my battery has a charge capacity limit, and I don't know if it is a good idea to use high capacity batteries, because I never found more than 2600mAh cells in computers (maybe had lower cycle life?). Can I buy NCR or INR batteries if actual cells are ICR? The cells are well known 18650.

I hope you can help me and other people that want to take a chance fixing it instead of buying new and expensive ones (my battery costs 100€ and only lasted 1 year without intensive use...) or cheaper ones with important wear level.

Thanks a lot!


texts: Is it possible to solder wires small 0.5mm to 1mm diameter vias?

texts:
I need to reprogram the micro-controller on my keyboard. I am new to soldering and would probably buy some equipent and try out on some regular size through holes. I am wondering if it would be possible to solder wires to these tiny vias(looks to be 0.5 - 1 mm diameter.) Maybe it would be helpful with some high flowing solder?

Any tips are appreciated. Thanks in advance.

Below is a pic of what kind of hole I am talking about.


texts:
This is a picture of a system that I am building:

(original)

I am writing SystemVerilog for the Counter4to3 module, whilst the other modules (Full adder and half adder) have already been provided to me.

So far for the Counter4to3 module I have:

module Counter4to3(input logic a3, a2, a1, a0,
  output logic y2, y1, y0);
  FullAdder(a3,a2,a1, , );
  HalfAdder( ,a0, ,y0);
  HalfAdder();
endmodule

I am having difficulty determining some of the inputs and outputs for the full adder and half adder modules. For instance, one of the full adder modules is actually an input to one of the half adders, and because of this, I am not sure what its output should be as it is not exactly one of either a3,a2,a1,a0,y2,y1, or y0.

I appreciate any help,
thank you for your time.


texts: Running an integrated speaker amplifier board off DC?

texts:
I found a pair of stereo speakers that come with an amplifier inside them.
They do run on mains voltage as they plug into the wall but the actual amplifier runs on DC, 12V to be precise. There is even an unused port that says 12V DC, presumably for a wall adapter. The first component in the circuit of those speakers is a center-tapped transformer that steps down the mains voltage to 12V (still ac). The outputs of the transformer are two 12V AC wires that directly connect to the full wave rectifier on the amp board and one center tap for getting the ground potential (hence the two 12V wires). In the end, the main audio controller and amplifier chips run on 12V DC.
Can you run this amplifier from a DC source, like a battery, if we ignore the transformer and directly connect it to the board?
I am asking this because I am planning on building a portable speaker with the components of these speakers.


texts:
I'm attempting to use PID for DC motor control. The motor is geared, with a magnet on the motor shaft coupled with a single hall effect sensor to help measure speed.
This is all wired up to a capture and compare timer on a STM32.
In my application, the frequency of the measuerment is between 0Hz and 100Hz depending on motor speed. The period between each pulse does vary so wondering what the best kind of SW filter to use ? Currently im averaging over 5 samples, but doesn't seem to be elimnating the error that well.


texts:
I have 6 buttons on my printed board, and I'd like to use interrupts on them all, but they don't correspond to the interrupts listed on the specs.

Is it true that you cannot choose arbitrary pins to use as interrupts on Arduino boards (specifically the Mega 2560)? If not, I am a bit sadface - any pragmatic workarounds?


texts: how to add switches to the end of the rotation that will cut off a stepper motor so I don’t damage anything at the extremes of the motion?

texts: I need to work on how to add switches to the end of the rotation that will cut off a stepper motor so I don’t damage anything at the extremes of the motion. I'm using a Dual - H Bridge to control the motors. I'm also using an arduino mega.  So basically I want to incorporate the switches into my motor circuit. If anyone has any advice or information please feel free to comment. I'm fairly new at this so any help will be much appreciated! Thanks in advance!


texts:
I have a problem with a relatively simple board which consists of an ENC28J60 Ethernet controller and an ATmega168.

The circuit around the ENC28J60 is straight out of the datasheet and I have the same circuit built up in a prototype with DIP parts where it works, but in my SMD version the ENC sucks down 40 mA @ 3.3V and it gets pretty hot.

The datasheet mentions that a relatively high current is sunk by the two TPOUT pins and that the total current is around 180 mA, but there is no mention of how much current the ENC itself will pull out of VDD.

The oscillator runs perfectly and CLKOUT is 6.25 MHz, so the chip is not completely dead.

I've measured the voltage at every pin and:

Every VSS pin is 0V
Every VDD pin is 3.3V
The oscillator and CLKOUT out are good.
VCAP is 2.65V
RBIAS is at 1.2V.
!RESET is 3.3V.
SPI looks ok.

Yet, I can't seem to raise the chip over SPI from the AVR and it gets pretty damn hot.

I've tried yanking !RESET low and that doesn't affect the power usage. Any clues?

Notice that the pin numbers for OSC1, OSC2, VDDOSC and VSSOSC are wrong in the schematic, I fixed that bug after exporting that version of the PDF however it is no longer available online.

OK, here's the real list of problems with my design that led to my problem:

My 3.3V regulator is dumping waaay too much power, so it gets too hot.
The ENC28J60 eats lots of power, even when working normally, so that gets hot too.
I messed up and forgot to double check the Eagle library pinout, so I had to do some board hacking to fix that.
The RX center tap should not be connected.
I forgot to update my Makefile to build for the Mega168 part.

Problem number 5 was the real source of my problem, #1 & #2 kept me looking at the hardware for far too long, which is doubly embarrassing because I make my living writing software.


texts:
I have a circuit as shown below

simulate this circuit – Schematic created using CircuitLab

Where R1, R2 are resistors. jX1 and jX3 are reactants, and jB2 is admittance. That being said, I'm not sure how to find Zin (Total input impedance). I have 2 theories:

Convert jB2 to impedance by taking its inverse (Z = 1/Y) and find total impedance:
$$
Zin = R1 + jX1 + ((R2 + jX3)||jB2)
$$
Just ignore the admittance in this calculation since it's not an impedance
$$
Zin = R1 + jX1 + jx3 + R2
$$

I'm not sure which one is correct. Both seem to be correct to me. Any help would be appreciated!


texts:
Here is a circuit that seems to work pretty well for allowing a voltage to control a current of up to maybe two amps.

It works on the falstad simulator (the triangle wave voltage input produces an identical current waveform thru the diode which is the LED -- Not only does PWM control work, setting input voltage to half will actually halve the current) and I will be breadboarding it with my own components but I want to figure out some things before I can finalize the circuit design.

The waveform at the left represents the voltage that regulates the current through the diode. The triangle wave (the 40Hz and the choice of triangle wave are arbitrary) is at 5V. It's connected to the op-amp through a voltage divider, and the pink resistor on the bottom right is chosen in coordination with the voltage going into the opamp (after the divider it is 100mV). The purpose of setting it to \$\frac{1}{7}\Omega\$ is to minimize heat generation. It is at that value because I wanted 700mA through the diode.

The DC voltage source on the right is 10V.

Now I looked at the spec sheet for my opamp, the MCP600x and it's absolute max current is 2mA. The Darlington pair transistor I am using (BD681) has a \$h_{FE}\$ of 750 which means that when I reach this limit the collector current is \$2mA*750=1.5A\$. This means I shouldn't use this circuit to drive a 3 amp LED. Do they make rail-to-rail opamps with higher current ratings? My transistor is rated to 4A (though it will need some heatsinking since it's got a 1.3v drop)

Since the transistor dissipates quite a bit of heat at high currents, I think a MOSFET would be necessary to reduce inefficiencies. However I haven't had very much luck getting a MOSFET circuit to have good current regulation because there is no conductive path from the gate to the source. I am able to use it as a switch, however, so PWM operation is okay.

I guess my question is: is there a relatively simple way to build a mosfet circuit that functions like this one, but capable of more current (and higher efficiency)? Also, which type of MOSFET should I be using (p-type, n-type... other types?)?


texts:
I am working on a design for a high-speed data acquisition device for a 10-bit ADC signal at 80 Msps. So far, it looks like most MCU boards are too slow to be able to route and store data and keep up with the high sampling rate. The latest board that I've been looking at is the Teensy 4.1 with a CPU frequency of 600 MHz (can go higher with overclocking, up to ~1 GHz with cooling). What I am wondering is if I can circumvent this issue by interfacing the ADC output directly with the I/O pins on a memory IC or SDRAM chip. In this scenario, I would use the Teensy 4.1 to drive the clock signals and logic signals for both the ADC and SDRAM.
In order to read the data from the SDRAM, I would use a multiplexer to re-route the I/O pins on the SDRAM to the Teensy 4.1, which can process the data and write it to external memory via SDIO. The multiplexer would only be used to switch the signals after my measurement is complete.
I've included a schematic below for what I am trying to describe above. Is this something that can physically be done?


texts: I am currently working on a 8051 assembly program which receives a set of BCD inputs and calculates the mean of this set. However, I couldn't figure out a decent way to divide 24bit BCD number. For instance, say that the sum of the series is 154128 and I am storing this data in 3 bytes: 15H, 41H, 28H and need to divide this by 13. Any ideas how should I proceed? Thanks already.


texts: Help drawing a circuit diagram from a logic diagram

texts:
I have managed to work out a logic circuit with 3 inputs and 5 outputs, but I have no idea how to translate this into a circuit.  I am guessing it will require IC's or many transistors.

The inputs are A, B and C, and the outputs are 1, 2, 3, 4 and 5.

Depending on the input state, the output should change as follows:

ABC - O
=======
000 - 3
100 - 1
110 - 2
010 - 3
011 - 4
001 - 5
111 - 3

And some pictures to help explain it (I hope)

A off, B off, C off = 3 on

A on, B off, C off = 1 on

A on, B on, C off = 2 on

A off, B on, C off = 3 on

A off, B on, C on = 4 on

A off, B off, C on = 5 on

A on, B on, C on = 3 on


texts: Trying to understand the magic the author of this PDF did explaining the critically damped equation

texts:
I am reading this doc about the equations for the step function for the RLC circuit, critically damped solution.

At page 16 we have these lines...

But there is a magic between these lines...

How the first line became the second one?


texts:
I'm trying to power up my NXT Mindstorm Brick which needs 7.4V (at least, that's what the battery output is) with a 12V Power Adapter. I'm doing that because I want a constant supply from the socket without the need for a battery.

I have to use a 12V adapter because, at the same time, I'm using a fan which needs 12V.

How do I reduce the 12V to 7.4V or somewhere near?

I'm thinking of using a voltage regulator but can't seem to find any that regulate to 7.4V, if there's no other way, I might just use a 7V voltage regulator.

Alternatively, is there a way to step 7.4V up to 12V? That way I can use a 7.4V power supply, whichever works more efficiently.


texts: Converting full adder to subtractor using inverter

texts:
I've been trying to convert a full adder to a full subtractor using an inverter.
I tried using not gates at the B input ( in A B Cin ) and also using it in the outputs but the final answers are not matching.


texts:
Harold A. Wheeler, “Fundamental Limitations of Small Antennas,” has introduced the concept of "boundary sphere", where the smallest sphere or circle surrounding an antenna has interesting implications in path loss equations.

Hans Gregory Schantz from Q-Track Corporation has calculated the maximum gain for an electrically small antenna.

Source: http://robotics.eecs.berkeley.edu/~pister/290Q/Papers/Antennas%20propagation%20interference/near%20field%20path%20loss.pdf

The formula I have marked with green, turns out that since the law of conservation of energy, and because 1 antenna can't be inside the other antenna's boundary sphere, he has derived this equation, where the gain of an electrically small antenna has to be smaller or equal than this.

Well it turns out this is formula is derived from the path loss equations:

$$k=\frac{2*\pi }{\lambda} $$
$$d=distance\hspace{0.3cm}between\hspace{0.3cm}the\hspace{0.3cm}antennas (meters)$$

Friis formula for farfield Planewave
$$PathLoss_P=\frac{G_t * G_r }{4}* (\frac{1}{(kd)^2})$$
Schantz formula for nearfield E-field
$$PathLoss_E=\frac{G_t * G_r }{4}* (\frac{1}{(kd)^2}-\frac{1}{(kd)^4}+\frac{1}{(kd)^6})$$
Schantz formula for nearfield H-field
$$PathLoss_H=\frac{G_t * G_r }{4}* (\frac{1}{(kd)^2}+\frac{1}{(kd)^4})$$

Specifically the formula above is derived from the E-field pathloss equation introduced also by Schantz in another paper, the coefficients are the same basically. He used "R" to denote the radius of the boundary sphere, we will use "d" to denote the diameter.

Does this mean that we can logically deduce the maximum gain of a nearfield magnetic antenna or an antenna in the far field to be the following, based on the this logic:

$$k=\frac{2*\pi }{\lambda} $$
$$d=diameter\hspace{0.3cm}of\hspace{0.3cm}boundary\hspace{0.3cm}sphere$$

$${Gain_P}_{max}=\sqrt{ \frac{4}{(\frac{1}{(kd)^2})} } $$
$${Gain_E}_{max}=\sqrt{ \frac{4}{(\frac{1}{(kd)^2}-\frac{1}{(kd)^4}+\frac{1}{(kd)^6})} } $$
$${Gain_H}_{max}=\sqrt{ \frac{4}{(\frac{1}{(kd)^2}+\frac{1}{(kd)^4})}} $$

Would this be a logical deduction? I would love to hear professional engineer's comment on this.


texts:
Is it possible to change counter signal to analog signal in Siemens Logo?
When Cnt is for example 4, then the Analog Threshold Block is going to giving out a high signal, else low signal.


texts: Is building a long range wifi antenna to connect to the up and coming starlink internet possible?

texts:
I want to try to convert a residential satellite dish into a long range wifi antenna to theoretically see if I can connect to the up & coming starlink internet that is being released in Canada and United States from virtually wherever.
It's just an experiment, and I don't intend to use it for illegal purposes. I imagine there must be some sort of security feature that would stop me from intercepting starlink wifi signals. But this is my first time ever doing anything of this nature, does anyone have any experience with intercepting or capturing wi-fi signals or could maybe tell me why my line of thinking is incorrect, or maybe if I'm possibly going in a right direction?


texts: I have seen many posts where a simple AM transmitter can be made with a crystal oscillator and modulation transformer. Can this idea somehow be modified to FM. I don't want people to misunderstand me. I don't mean a crystal locked FM transmitter - these are everywhere. I mean a crystal oscillator somehow able to modulate FM? Does every FM transmitter need a VCO or is there another way to do it?


texts:
I have implemented ram Verilog module. I made its instantiation and read the data from some address .After that I want to write the data to other address.
looks that I don`t need to made the instantiation of the ram twice,since each ram defines different registers array.The question is how (should I?) reuse the same ram instance?

module ram(we,addr,data);

input we;
input[DATA_WIDTH - 1:0] addr,
inout[DATA_WIDTH - 1:0] data;

reg [DATA_WIDTH - 1:0] mem[0:ADDR_DEPTH - 1];
always @ ( posedge clk )
begin
if(we)
mem[addr] <= data;
else
data <= mem[addr];
end
endmodule

module top (add1,add2);
wire [DATA_WIDTH - 1:0] w_data;
ram i_ram1(1b'0,add1,w_data);
ram i_ram2(1b'1,add2,w_data);//<- other mem array is used in this instance


texts: Why is the cache size identification register on ARM CPUs accessible from privileged modes only?

texts: Is there any logical decision making behind this, to my understanding it exposes only the same information as CPUID instruction from x86 so why is it only made accessible to EL1? Is this in some way more secure, or perhaps it is just "over security"?


texts: Voltage regulator IC with external reference

texts:
Is there a linear regulator that can follow a reference?

The broader problem I have is that I have an ADC with reference that can only source 50mA (I have no control over the ADC or reference circuit) but I have some sensors that are low impedance and measured with a Wheatstone bridge so I need the same reference voltage but more current.

I thought of doing this (below) but there must be an IC that does the job.

simulate this circuit – Schematic created using CircuitLab


texts:
I have been analysing a PCB and have come across an IC I cannot seem to identify, so I am hoping someone here may be able to help. A picture of the IC is here:

Just in case people have trouble reading it, it is in an 8-pin SOIC package. The top line reads 7062, the middle line reads G007H and the bottom line reads JRC
I have tried to find this myself, and all I can find with the 7062 reference is an AN7062 which doesn't seem to have an 8-pin variant so pretty sure it isn't that. Googling G007H doesn't throw up much else. The JRC seems to be the manufacturer from what I can gather, and using this with the 7062 throws up THIS op amp, but I'm not 100% sure it is this as the IC next to it is a TL064I quad op-amp. There is of course every chance that it could be the IC I found, but it just doesn't seem to fit.
If anyone has any idea, and is better at Google than I, then I would be grateful if anyone is able to identify it.


texts: Why do we get Non uniform plane waves along a transmission line?

texts: I get that wave propagation will take place but why TEM mode is the only possible mode that can exist? And also why it is non-uniform?


texts: PIC16F88 digital output to gate of MOSFET - Voltage / Current questions?

texts:
I'm new to electronics. If I say anything that's presumptuous or just flat out weird or wrong, please point it out. There are many gaps in my knowledge.

I'm working on a simple personal project. I want to use a PIC16F88 microcontroller to toggle an LED on and off at regular intervals. I'm using this LED. If I'm interpreting the datasheet correctly, this LED is happiest when it can draw 30mA - which I'm told is quite greedy for a little LED like this. In any case, the PIC16F88 would struggle to source or sink this much current on any of its I/O pins, so the solution seems to be to use a BJT or MOSFET.

I decided to use this MOSFET - which seems a little overkill, but it's what I had available. The plan is to configure a pin on the microcontroller as a digital output, and then in software just set that pin HIGH, then sleep, then set it LOW, sleep, repeat. This signal would trigger the gate of the MOSFET and allow the desired current to flow through the LED (with a 100 Ohm resistor in series with the LED).

Here's where my questions start:

In my configuration, the PIC16F88 outputs a LOGIC HIGH at +5V. If my digital output pin is directly connected to the gate of the MOSFET, do I need to limit the current of this pin in any way, like with a resistor? I mean, I know I'll have to limit the voltage to the gate (the datasheet says the MOSFET expects a typical Gate Threshold Voltage of +2V, with a maximum of +3V), but what about the current? I certainly wouldn't want the microcontroller to try and source more current than is desirable for the I/O pins, so in a sourcing configuration, around 1.6mA? Less than that? I'm basing that guess on an answer I got for a different question I posted about the same microcontroller, where the user @glen_geek writes:

  It appears that an I/O pin can sink current (8.5mA) with less stress
  than it can supply current (1.6mA). These are not limits, but are a
  single data point within the maximum limits stated elsewhere (Section
  18.0 states that maximum current on any one I/O pin shouldn't exceed 25mA).

I don't really have room for experimentation, because I don't have access to a multimeter at the moment. How would I even know how much current my pin-to-gate connection is drawing? I realize that MOSFETs are voltage-controlled devices, so does any of this even matter? Does the MOSFET only draw as much current as it needs at the gate (does that even make sense)? I also know you can have voltage without also having current... is it kind of one of those things? You can tell I'm flailing at this point.

Finally, one more tangential question: Is it possible - or does it even make sense - to achieve a configuration in which the pin is sinking current (which would be desirable apparently because the microcontroller can do this more easily), and in doing so, triggering the gate of the MOSFET? I thought about this for a while but it doesn't really possible - perhaps not even useful, seeing as how I'd be using a MOSFET to do the heavy lifting anyway.

Thanks for any feedback.


texts:
I've created a board with an outline that was created on the edge cuts layer.  I've selected 'Board area only' and I've deselected 'Print board edges'.  When I try to plot the SVG file for the F.Cu copper layer, it plots the entire drawing sheet instead of the board alone.  What am I missing?  I haven't found any similar issues documented regarding svg exporting =(

I'm curious if there is a configuration setting I need to check elsewhere? Any troubleshooting advice is appreciated.

I'm using KiCad Application: KiCad (5.0.2-5)-5, release build on OSX 10.13.

Unfortunately, the svg is not cropped to the board area only.  See below


texts: Suitable Substitute for this Varistor MDC Z750 / 40

texts:
I am in the process of restoring a vintage EZGO Golf Cart and have came across a component I am unable to locate within the generic golf cart electrical diagram.
This varistor is from a 36 volt DC control circuit on a 1991 EZGO Marathon Golf cart, located between two terminals. I have researched the electrical diagram for this circuit and it does not show the varistor there. It may have come with the controller and the controller does not have an electrical breakdown diagram - just the connection leads.
I have researched online for a varistor with these markings:     MDC Z750 40 with no luck. I am assuming, since the cart runs on six 6-volt batteries, the clamping voltage is 40 / it is a zinc oxide varistor and the manufacturer: MDC - Company Initials "Maida".
I am looking for a distributor that would sell a couple of these varistors or a recommendation for a suitable substitute that I can purchase. I contacted Maida directly and they responded with:

Unfortunately we do not offer parts for replacement purposes.  We recommend that you follow up with Online Components.

Thank you for your time regarding this query. Photos attached.


texts: 7-Segment Drivers: How do they work/how to handle them?

texts:
So I know to drive a 7-segment display you need a TON of pins. However there are 7-segment display drivers (such as the MAX7219) that seem pretty popular.

However I'm looking at the datasheet, and am a bit confused. (https://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf). It mentions the SEG A-G connecting to the obvious segments of the 7-segment display (AND2307SLC mentioned in the datasheet)...but what exactly are the DIGI 0-7 for then? (But then on page 13 it shows them actually connected.)

Maybe I'm a bit confused how it works exactly. From my vague understanding we send it serial data to the DIN pin of what segment we want to display, and it outputs that to SEG A-G. (We send 16 bits, and it only looks at the last 4 correct?) (BTW this makes me not understand what LOAD is for exactly.)

And then there is decode mode, which I guess is the main way to turn on digits via serial as opposed to just turning them on via DIG7-DIG0.

Am I even on the right track on this? I'm just a bit confused how it all works together. Also I'm curious how it handles turning on multiple segments when doing it via serial.  Is it storing something in SRAM and then uses some sort of timer/refresh to keep the digits on?

Thanks, it's just sort of an interesting chip that I'd like to learn more about.


texts: Why we need to have a current output on power supply to drive some devices (such as curve tracer)?

texts:
Last week, I just had an experiment on lab, in which I need to use a transistor curve tracer board and thus was asked to connect it to a digital supply.

I connected them and sat voltage output of power supply as 12 V (as said in my lab note) and 0A. However, the tracer did not work correctly. I asked my mentor and he said I need to set a current output like 1 mA to supply enough supply, which finally worked.

My question is, why we need a current output on power supply or why it won't have a current output automatically? I do understand that if the power supply has 0 A current, based on P = UI, there is no 0 W of power supply. However, if I connect a 12V and 0A power supply to a 1k ohms, it will have a 12 mA current on the circuit, which means the power supply provide current "automatically"?


texts: Designing a non-inverting buck-boost converter

texts:
I am trying to design a non-inverting buck-boost converter using 4 switches (transistors).

Note:The schematic is taken from Texas instruments.
This can be summarized in the following points:
1- The non-inverting buck-boost converter usually comes with two-switches and two diodes. However, I will replace the two diodes with two transistors and that is known as a four switch buck-boost converter.
2- I would like to choose the values of the parameters but I have one issue which is that I could not find a good reference with the relevant equations that will help me to calculate the parameters. Therefore, Could you provide a good reference where I can find the equations or the equations themselves.
3- The input range of the converter will be big like 8v-70v and I want to regulate the voltage to say 12V and the switching frequency will be high 100khz or even greater than that to achieve a higher frequency. (to offer a step-up and step-down)
4- Can I simulate the converter in simulink even though the four switches may need to operate on a complementary (for example,as I understood,we will have two different duty cycles D1 and D2 and these need to have different values if we want to operate the converter efficiently).
Can someone please answer my questions. Thanks for your help in advance.


texts:
I have a DS89c450 which I wish to program and so far have had no success. I have no programmers, so I need to utilise the ISP capabilities. I have the crystal connected (16Mhz) as well as the power. The data sheet indicates that EA and RST need to be pulled up, and PSEN needs to be pulled down to enter programming mode. Can these be connected straight to VCC/GND or do they need to be connected through a resistor? If so, what size would suit?

By using USB to Serial, I no longer need a 232 transciever do I? That would only apply to programming through a conventional serial port wouldn't it?

Once hardware issues are solved, I need to be able to program the chip. I have installed Kiel with C51 addon. I believe this is all I need to write the program. Following this, how will I write the software onto the chip? What software will I require to do so?

Whilst there are some tutorials online, they all provide basic information, not enough for a beginner. I'm hoping that any answers will be detailed enough to assist other beginner 8051 people like myself.


texts: Bench Power Supply for ESC and KV on motor

texts:
I have a bench power supply it can provide ~10 amps and ~30 volts. Working on an autonomous car project I have an ESC to manage a brush-less motor.
Two questions I cannot seem to wrap my head around:

The ESC has a 35A requirements. With the bench power supply I have I can only go to 10A. If I am powering the ESC with this what are the risks? Over heating the supply? I set the volts to 13v based on the 35A specs.

The motor stated 3600kv or 36v (if I understand correctly). Do I need to be concerned with this? The ESC manages that so as long as I manage the 35A the motor is fine. Why do I need to know this metric?


texts: OrCAD Capture Question: Replace Bias Voltage Marker

texts: If you delete a bias voltage box (pictured below), how do you go about replacing them?


texts: Line regulation of zener diode with jfet

texts:
How am I able to calculate line regulation (S=dUout/dUin) for zener diode with current provided by JFET with zero gate - source voltage? Schematic below

Lets say it's typical BF256B as JFET and BZX84-B5V1 as Zener diode.
Is it calculable or just equal 0?


texts: Why does my waveform start ahead of the trigger?

texts:
I am learning how to analyze SPI bus clock and data using an entry-level digital storage oscilloscope. I'm using a BK Precision 2542B to measure the output of the clock and MOSI lines from a Netduino that utilizes an ARM microcontroller.

In this image, I have the clock on channel 1 (yellow), and the MOSI on channel 2 (blue). The trigger is set to use channel 1, using a rising edge trigger of 1.44V. The clock square wave amplitude is about 3.3V.

The trigger indicator is at the center of the display horizontally, yet I have a pulse to its left. I was expecting the first pulse of the clock to start at the trigger location. I know that a digital storage oscilloscope allows you to see pre- and post-trigger events, but I'm confused why the first pulse isn't where I thought it would be.

Is my understanding of triggering incorrect, or am I just using a weird scope?

Edit: The pulse train is 300μs wide, repeats at 2ms intervals, and I have a trigger hold off value of 500μs. Adjusting the hold off has not changed the fact that one pulse precedes the trigger.

Edit 2:

After more analysis of the signal, including using the analog oscilloscope, I think I've determined that sometimes the pulse duration is about 350μs instead of 300μs. This may be a glitch in the code generating frames.

I discovered that a hold off time of 352μs will produce the expected result, but every now and then an extra pulse precedes the trigger.

I recorded some frames to show the pulse both absent and present:

If I set the horizontal time base long enough to see the pulses' duration, there always appears to be at least 1.7ms between them:

So while I think the leading pulse is a result of a "glitch" from the source, I'm still not sure how a trigger hold-off >360μs still produces the unexpected leading pulse.


texts: Isolation for TO-247 Leads at High Voltage (1000V)

texts:
Regarding the fairly new High Voltage SiCFET Devices with operating voltages of 1200V+ in leaded TO-247 packages (or variants thereof):

How to isolate the Gate-, Drain- and Source- leads (and heatsink) from each other?

Is maybe isolation between the leads ensured even without additional isolation efforts (assuming no moisture, dirt or dust)?

SiCFET example: SCT50N120


texts: Harvest energy from ultra low current and high voltage source?

texts:
I have a sensor which can produce voltage upto 10 V but can only produce 50 nA of current. I tried to harvest energy using TI's BQ25570 evaluation board but the current is too low to kickstart the board. Also, the sensor is a high impedance source.

How can I harvest energy from this sensor?

Can I boost the current somehow? Would a Darlington pair work for this purpose?


texts:
I'm tying to use a atmega2560 but can't get the I2C working.
When I send the address byte i get never a ack response.
Does anyone see what i'm doing wrong i used the code out of the datasheet?
I tried it with a logic analyzer and it works so I do know the IC isn't defect.

void i2csend(uint8_t addr, uint8_t reg, uint8_t data){
   TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);
   while(!(TWCR & (1<<TWINT)));
   if ((TWSR & 0xF8) != 0x08)//A  START  condition  has  been transmitted
   {
    stopi2c();
    return;
   }
   TWDR = addr;
   TWCR = (1<<TWINT) | (1<<TWEN);
   while(!(TWCR & (1<<TWINT)));
   if ((TWSR & 0xF8) != 0x18)//SLA+W has been transmitted;
                               ACK has been received
   {
    stopi2c();
    return;
   }
   TWDR = reg;
   TWCR = (1<<TWINT) | (1<<TWEN);
   while (!(TWCR & (1<<TWINT)));
   if ((TWSR & 0xF8) != 0x28)//Data  byte  has  been  transmitted;
                               ACK has been received
   {
    stopi2c();
    return;
   }
   TWDR = data;
   TWCR = (1<<TWINT) | (1<<TWEN);
   while (!(TWCR & (1<<TWINT)));
   if ((TWSR & 0xF8) != 0x28)//Data  byte  has  been  transmitted;
                               ACK has been received
   {
    stopi2c();
    return;
   }
   stopi2c();
   return;
}


texts:
I have two JK-flipflops with outputs Q_1 and Q_2, with two extra input signals A_1 and A_2.
They need to do the following (the truthtable just contains 3 examples, it's not complete):

How do you make an optimal sum of products for both JK flipflops with the use of karnaugh maps in this example?

edit: this is the transition diagram with outputs for all Q2Q1(n-1) and A2A1 values.


texts: Can a circuit be powered from Earth with a return ground on Mars?

texts:
Could you use a hot wire (120v 60 hz) from earth and a copper rod inserted into another extraterrestial body (mars) to complete a circuit? If impedance wasn't something to worry about (pretend Mars is only a mile away or something).

I've asked this before on other places and got some really conflicting answers.


texts:
I am trying to set up an I2C communication between a Xilinx Zynq-7000 SoC-FPGA and an external micro controller. The FPGA is the slave and an external micro controller is the master. The micro controller should be able to write to and read from the BRAM registers via the I2C interface. The micro controller can access these BRAM registers using the corresponding address. The PS of the Zynq-7000 SoC can also write to / read from the BRAM registers, using a AXI BRAM controller.
The micro controller communicates with an I2C IP, which accesses the BRAM via the BRAM A port. The PS can access the BRAM using the BRAM B port which is connected to the AXI BRAM controller.
Now I am trying to check if the values which are written by the PS (on the BRAM B port) are equal to the values which are read by the I2C IP (on the BRAM A port). However, this is not the case. For example, I wrote 0x81 to address 0x40 of the BRAM using the PS. See the figure below.

When the micro controller requests the value at address 0x40, the I2C IP reads the value 0x01 from address 0x40. See the figure below.

The value 0x01 is written to address 0x40 by the micro controller at the initialization. The value 0x81 is written to the address 0x40 by the PS ever 4 ms.
Can anyone see what is going wrong here? It seems like address 0x40 is a different location at the BRAM A port than at BRAM B port, but I am not sure is this is possible. And if this would be the case, I am not sure how to solve it.
The BRAM is defined as follows:
BRAM_TDP_MACRO_inst : BRAM_TDP_MACRO
generic map (
    BRAM_SIZE => "36Kb",
    DEVICE => "7SERIES",
    DOA_REG => 1,
    DOB_REG => 1,
    INIT_A => X"00000000",
    INIT_B => X"00000000",
    INIT_FILE => "NONE",
    READ_WIDTH_A => 8,
    READ_WIDTH_B => 32,
    SIM_COLLISION_CHECK => "ALL",
    SRVAL_A => X"00000000",
    SRVAL_B => X"00000000",
    WRITE_MODE_A => "WRITE_FIRST",
    WRITE_MODE_B => "WRITE_FIRST",
    WRITE_WIDTH_A => 8,
    WRITE_WIDTH_B => 32,
    -- The following INIT_xx declarations specify the initial contents of the RAM
    INIT_00 => X"0000000000000000000000000000000000000000000000000000000000000000",
    INIT_01 => X"0000000000000000000000000000000000000000000000000000000000000000",
    INIT_02 => X"0000000000000000000000000000000000000000000000000000000000000000",
    ...
    INITP_0E => X"0000000000000000000000000000000000000000000000000000000000000000",
    INITP_0F => X"0000000000000000000000000000000000000000000000000000000000000000")
port map (
    DOA    => bramA_rd_data,
    DOB    => bramB_rd_data,
    ADDRA  => bramA_addr,
    ADDRB  => bramB_addr,
    CLKA   => clk,
    CLKB   => bramB_clk,
    DIA    => bramA_wr_data,
    DIB    => bramB_wr_data,
    ENA    => bramA_en,
    ENB    => bramB_en,
    REGCEA => '1',
    REGCEB => '1',
    RSTA   => bramA_rst,
    RSTB   => bramB_rst,
    WEA    => bramA_we,
    WEB    => bramB_we
);

I used the Vivado HW monitor to debug the BRAM ports.


texts:
ohm's law says that V = I*R
And so
I = V/R
But what happens if we have a circuit with 0 resistance?
That would make everything else 0. What does that mean?


texts: Harvesting energy from a small amount of wind

texts:
I am currently investigating the feasibility of a project that would include the need of harvesting some energy from wind. The size constant of the generator and fans is about 2"x2"x2". The end goal would be to trickle charge a capacitor that would then be used in a very low power wireless application. 2-3.3v is the operating range that is being considered at the moment. I have 2 questions that I believe are related enough to be in a single question:

I know a simple small DC motor can be used to produce some power, but my instinct tells me that a DC motor wouldn't be as efficient as a device that is specifically designed for this purpose. Is my instinct correct? If I am, is there any specific name for what this device is called? I know it is a generator, but that name is so broad it is hard to find anything that is related to small applications.
How can I estimate the amount of energy that can be obtained based off of wind speed? I realize that there are many things that can affect this calculation, but I am just trying to determine some rough numbers.


texts:
I have an old PCB that uses this clock generator (means I'm absolutely sticking to the schema). The IC is standard 7400, resistors are the same, but the capacitors I'm using have 470 uF (500's are hard to come by). The clock drives a traffic lights simulator, hence the period is 1~2 seconds.

When I increase the the variable resistor to about 75%, the clock stops. O-scope shows me both the capacitors are discharging more slowly, and the voltage on the gate inputs gets stuck in the undefined region.

That brings me to these questions:

Why this keeps happening?
What's the relationship (equation) between the R and C in each "branch"? Should I increase the C, or lower the R, or what exactly?
how are the capacitor & resistor values calculated = Timing / voltage / current requirements, considering the IC used?
Anything else needs to be mentioned? (School me please)


texts: How to keep led in "ON" state using 555 IC?

texts:
I have made dark detector using this following circuit diagram:

Whenever the LDR is closed with finger,the LED would glow. Now all I want is to keep that LED in ON state for a while or alternatively stay ON until the reset button is pressed (if possible), so that it can be used as laser burglar alarm (but with LED instead of buzzer). How can it be done using a 555 IC?


texts: How much power does a wireless mouse use?

texts: I have seen many answers online to how much power the USB dongle linked to a wireless mouse uses, but nothing about how much power the actual mouse draws from its batteries. What is a ball-park estimate on how many milliwatts a generic wireless mouse uses when it is being moved, and when it is being idle?


texts:
I have been looking everywhere for a method to use i2c over a 12-48V DC power bus.

Are their any current IC solutions that I could check out?

If not where would be a good place to start on such a design? I know I could put an rf choke in before I inject the comm's and after I take it out but that really only works with >1MHz.


texts: Worried about channel ghosting in DAQ system - Need unit gain buffer?

texts:
I am working on a redesign of a test box we have at work. There is a transmitter that is sending data to a recording system (in my case the dewetron trendcorder with Trion BNC modules). We previously outsourced the design of this test box and that company used unity gain buffers from the transmitter side into the recorder.

The output impedance of our transmitter is less then 10K ohms and the input impedance of the recorder is 10M ohms. With that ratio I am not worried about a significant voltage drop but I am worried about channel ghosting as we will be switching channels. The trion module doesn't specify the input capacitance for its internal ADC.

We are trying to make this redesign as simple (and cheap) as possible and not having to design a PCB (even though its fun!) would save a lot. I am trying to decide if the vendor was overly cautious with these unity gain buffers or if they do serve a purpose. I am using this tutorial from NI for reference. Ghosting tutorial

I am leaning towards the side of just designing the PCB to be safe. Is there something else I need to be aware of here?


texts:
Is is possible to link an ACS712(http://www.alldatasheet.com/datasheet-pdf/pdf/168326/ALLEGRO/ACS712.html) module to a 220V electrical socket? I can't say if the module is built for low or high voltage.(I'm not an electrical engineer)

If no, what I should use instead?

I need it for measuring the power consumed using an MCP3008 interfaced with a Raspberry Pi.

Thank you!