texts:
What I am trying to do is, I want to use Key 0 as a upcounter and key 1 as a downcounter in the same program. I can do that separately. So, when enable is triggered, pressing key 0 will increase the value shown on a seven segment display and pressing key 1 will decrease the value. Following is my code.

/*
This program uses SW0 as the enable swithch.
And Key 0 as a upcounter, Key 1 as a downcounter
*/

module seven_seg_single_up_down ( en, in_up, in_down, a, b, c, d, e, f, g );
input en;
input in_up, in_down;

output a, b, c, d, e, f, g;

reg a, b, c, d, e, f, g;
reg [3:0]i;

always @( posedge in_up, posedge in_down, negedge en ) begin
    if ( ~en )
        begin
            {a, b, c, d, e, f, g} = 7'b1111111;
            i = 0;
        end
    //else if (in_up)
    //  i = i + 1;
    //else if (in_down and i > 0 )
    //  i = i - 1;
    //else begin

    else begin
        if ( in_up )
            i = i + 1;
        if ( in_down ) begin
            i = i - 1;
        end

        case(i)
            1:{a, b, c, d, e, f, g} = 7'b1001111;
            2:{a, b, c, d, e, f, g} = 7'b0010010;
            3:{a, b, c, d, e, f, g} = 7'b0000110;
            4:{a, b, c, d, e, f, g} = 7'b1001100;
            5:{a, b, c, d, e, f, g} = 7'b0100100;
            6:{a, b, c, d, e, f, g} = 7'b0100000;
            7:{a, b, c, d, e, f, g} = 7'b0001111;
            8:{a, b, c, d, e, f, g} = 7'b0000000;
            9: begin
                {a, b, c, d, e, f, g} = 7'b0000100;
                i = -1;
                end
            default: {a, b, c, d, e, f, g} = 7'b0000001;
        endcase
    end
end
endmodule

I don't understand what is wrong with the code above.


texts: Is A XNOR B logically equivalent to A XOR (NOT B)?

texts: I am just wondering if its fair to say that A XNOR B is logically equivalent to A XOR ~B? If yes, how do I justify that without a truth table?


texts:
can anyone explain why the graph is shifted up vertically by 40dB? is that what we have to do by summing all lines and then shift them up by the amount of DC gain?
I know that the DC gain is 20log10(100)=40dB and I can see where poles and zeros are.
Also, how can I find the slopes for each line?  I know there is a way to find it mathematically but I don't know how.

Thanks


texts: Wireless bridge for embedded ethernet switch

texts:
I'm building a robot which has an embedded 8 port ethernet switch on it (using a KS8997 controller IC). The reason for that is, that some components like the motor controllers are controlled via ethernet. So there is a CAT5 cable hanging from the robot that connects to my laptop.

I'm wondering if there is a simple solution to turn the wired robot into a wireless one using WiFi. Is it possible to connect a cheap "RJ45 to WiFi Bridge" to the uplink port on the switch?

Thanks for any hints!


texts:
What is meant by "state"in state space analysis?
Is it something related to initial conditions such as in RLC circuit in attached snap,we have two states
1)Current through inductor
2) Voltage across capacitor


texts: How to design Current Amplifier circuit to amplify the signal current to 1A

texts:
I am trying to design a current amplifier circuit to amplify a signal current to 1A.

Application :

I am generating a signal using microcontroller (for ex : Pic16f877A). This signal is 5v having 10mA current (approx not calculated). I want to amplify this current upto 1A - 1.5A to drive a device.

Can anyone suggest me better way to solve this issue ??


texts: Is there any problems or issues with holding !RESET low on ATMEL ATMEGA328P till rest of board self checks?

texts: I'd like keep an ATMEL ATMega328P in reset for about 4 sec while the rest of the board self checks on startup. Is this OK? Are there any issues that would make holding the RESET low for this extended period of time a bad thing to do? I could alternatively turn the power off, but it would be much much easier to just hold reset low, since that can be done with a logic gate.


texts:
I am having a potentiometer which gives an analog voltage in range of 0-5V. I am considering this POT as throttel input for motor.
If i change the pot speed increase and decrese on the basis of voltage comming from pot.
I am sensing the analog voltage from ADC of my ATMEL mcu. My MCU is working on 5V.

Let say analog input from the POT is 2V. And i am assuming that command signal is 200 RPM fpr motor.
My motor have hall sensor o/p from which i am able to read current speed of the motor which is say 120 RPM.

error = set_speed - current_speed  = 200 -120 = 80 RPM

Now i apply the PID to this error signal(80 RPM) i will get some controller o/p.

Motor speed is controlled by changing the PWM duty cycle (16 bit register).
But big question is that PWM use to control the speed of the motor. Now how to use this controller output to change the PWM duty of my MCU

How PWM relates to controller o/p signal to adjust the speed ?


texts: Plane Splitting - Single winding AC to dual rail on the same board as preamps

texts:
So I have asked a similar question and was wondering if I could trouble you guys for a little more advice. I believe I have taken all of the advice from before into account. Ill get right into it.

Above you can see my schematic, where the DC barrel jack sees 18VAC. This is sent through a doubler which is then smoothed and rectified twice. The reason for rectifying twice is to get improved ripple rejection.

There are many other parts to this board that are highly sensitive to any sort of noise, these parts will lie to the right of the power section as per figure 2. I have looked into splitting the ground plane and have come up with the following layout.

So the area on the far left is where the AC supply (18VAC) goes directly into the caps and diodes for rectification. After this, the remainder of the circuit is spead around before the rails emerge at the opposite end.

The ground plane for all of the power supply related compoennts only meets with the signal ground plane near the power inlet (top left of the board, fig 2(b)).

Here is a 3d render of what the components are.

So my question is this, will this actually achieve what I want it to achieve. Will there be no noise from the power section in the sensitive analog components that will be placed all to the right of the power section as per figure 2.

Is there some obvious principal that I have overlooked?

If so, is there any other way you would recommend doing this type of thing? Apologies if this question has offended anyone, I have experience with audio circuit design but have never put an AC power supply on the same PCB as preamps before.


texts: Cable screen terminations for enclosure containing SMPS and instrumentation signal conditioners

texts:
I'm looking for some help with some screening and cable termination decisions I need to make. I'd be grateful for any advice, and I'll do my best to explain myself clearly.

I am building a control panel for a tensile test machine. Please see the diagram for the functional blocks, and my explanation below for the finer details and my options as I see them. I have omitted power supply and watchdog connections; the signal conditioners and watchdog will be powered from the SMPS.

Key points:

Before installing the enclosure, I terminated the LVDT screen at the signal conditioner (DR7AC signal conditioner, http://www.rdpe.com/cds/cd2402.pdf
I use a screened cable from each signal conditioner to the DAQ, with the screen floating at the DAQ end and terminated at the conditioner end
I plan to adopt the same strategy with the load cell conditioner, which is mounted in a diecast aluminum box
The signals I am interested in are very low frequency (<30 Hz, mostly DC with smooth transitions)

My questions:

I'm confused whether or not I should consider the main wall enclosure as a screen termination point. That is, I want to place DIN receptacles on the panel, but this will cause my cable screens to be terminated at the large enclosure. I was planning to pass un-screened mains flex through a grommet to the disconnect switch, and I also have a SMPS inside the main wall enclosure, so I'm pretty sure I can't consider the large enclosure to be a screened environment.
Assuming that the answer to (1) is no, how then should I handle my cables and screens? If I use DIN plugs and receptacles on the main panel, then do I just continue with the screened cable on the inside, but leave it floating at the DIN connector end and terminate the screen at the signal conditioner? This is what my intuition is telling me.
Should I mount my diecast aluminum box containing the load cell signal conditioner straight to the back plate of the wall enclosure, which is grounded? Or should I insulate my internal screened enclosures, and use an earth lead to the panel star-point?

I hope this makes sense; I'm afraid I've been thinking about it for so long that I might have taken a detail for granted - please ask if anything needs elaboration. If anyone is prepared to help then I would be keen to have a dialogue.

Finally, I would like a solution using the parts I have mentioned; DIN connectors (3 pin and 5 pin), 2 and 4 core twisted and screened cable, grommets, and enclosures (a large wall enclosure is the main enclosure, and a small diecast enclosure for the load cell signal conditioner). The LVDT signal conditioner is a DIN rail mounted version.

Thanks for any help.


texts: Failed to find DC operating point for AC analysis with OPA388 third party OpAmp?

texts:
Whenever I try this imported OpAmp to simulate a Sallen-key 2nd-order OpAmp filter in LTspice, it never reaches the DC operating point.

Is it the spice model or the components' value?

I want to upload the file but no way here.


texts:
I am designing a solar powered charger for lithium ion battery.  Most reference schematics online add a diode for polarity protection right after solar panel (e.g. D1 of the circuit diagram http://www.electronicshub.org/solar-battery-charger-circuit/).

This makes me wonder if the solar panel can output negative voltages momentarily since I have no experience with solar panels.  Is the polarity protection really necessary?  Thanks.


texts: Method to determine least-error prescaler and top values for timer1 of Arduino?

texts:
If this question should be in StackExchange instead of here I can delete here and post there.

Using an Arduino Duemilanove (Atmega328) I am trying to generate a square wave (50% duty cycle) of frequency somewhere between 500 Hz and 200 KHz, as entered by a user. I do not need any variable PWM duty cycle, just a simple square wave. Also I can not use Timer0 since modification of that affects delay() and other time related functions of the Arduino.

The timer calculations for prescaler and top counter have me very confused, can someone point me to an algorithm to identify which combination of prescaler and top values will give the closest output frequency to the specified one? In many cases, two or more combinations of prescaler and top give similar output frequency results but neither is exact.

For example user enters value of 98350 Hz. How would my Arduino code find out what prescaler and top counter value to set the Timer 2 registers to, for the closest match to that frequency?


texts: Can I use an SMPS to power a audio TDA7293 power amplifier?

texts:
I have been gifted a couple of these TDA7293 Power Amplifier boards, and I need to give power to them. Description says

*DC power supply: positive and negative 25-45V
*The power of the transformer: 100w-200w

The DIY Audio forums talk about using a huge transformer + rectifier board for these amps. Can I use SMPS instead? The SMPS will be lighter than the transformer.

If SMPS can substitute the transformer, I must use two SMPS and connect back to back or a single SMPS with + and - is available? And is the current rating different for SMPS or same as transformer? Thank you.


texts: Problems connecting differential ADC to SPI chain

texts:
I need to connect 3 devices with SPI in a daisy chain configuration.1 master 2 slaves.
the first slave is typically connected to the master:
SCK-SCK
MOSI-MOSI
CS-CS
The second slave on chain have no MOSI input, only SCK,MISO and CS.
I can connect this slave device to the master (MISO) but I interrupt the chain beetween the two slaves.

The three device are:
- Master: ATmega32 (MCU) http://www.atmel.com/images/doc2503.pdf
- Slave 1: MCP23S17 (differential ADC)
- Slave 2: LTC1285 (3V 12-bit A/D Converter) http://www.farnell.com/datasheets/1575635.pdf

Is it possible to connect theese 3 devices in a daisy chain configuration?
Thanks for your help!


texts: How to know which radio frequency is free to transmit data over a particular frequency to avoid interference

texts:
I found that some radio broadcasting stations transmit data at a particular frequency, and I was told that if I were to transmit my own at that particular frequency that I would interfere with their signal.
That got me thinking:

How would I know when a frequency is free?
How would I stop other signals from interfering mine?
What kind of circuit would I use to implement this?

I am about to build a receiver and transmitter circuit, so this question popped up.


texts: Bluetooth module throughput / UART baud rate? How fast is it?

texts:
I'm choosing a Bluetooth module for my project.
Reading datasheets like this:

BM78 Module

I can see sentences like:

11 kbps (BR/EDR)@ UART baud Rate is 115200 bps •
 8 Kbps (LE) UART baud Rate is 115200 bps

Does "UART Baud rate" mean that the module can transfer only 1Kb/sec or 14Kb/sec? Is it not too slow for a standard Bluetooth 3.0 which promises at least 1 Mbit/sec?


texts:
What is exactly the difference between the Bandwidth and the carrier frequency ?
And if we have two channels with the same bandwidth but with different carrier frequency will we have different speeds ?
For example :

System A :
Bandwidth = 1 Khz ,
Carrier frequency = 1 Ghz
System B :
Bandwidth = 1 Khz ,
Carrier frequency = 1 Mhz

If we used 16-QAM in both systems will baudrate be the same ?


texts: I remember reading long ago that I don't need filter caps for a watch (32768 Hz) crystal. Is this true? Or will I need to put some capacitors to ground on either end of the crystal? I will be using the crystal as the primary clock source.


texts: Is it possible that a 12V transformer is creating EM interference that's coupling onto a long antenna cable?

texts:
I have an Arduino Mega, Adafruit RFM96W 433MHz LoRa Transceiver Breakout and 2 Channel OptoCoupler Relay Module.
https://www.adafruit.com/product/3073
https://www.amazon.co.uk/SUNFOUNDER-2-Channel-Optocoupler-Expansion-Raspberry/dp/B00E0NTPP4
The Arduino Mega runs a sketch that waits for the press of a button and then:
If Button A:
Switches on a 12V pump connected to the Relay for 30 seconds Then sends a radio message (using RH-RF94 library) to another device
If Button B:
Sends a radio message (using RH-RF94 library) to another device https://github.com/kenbiba/RH-RF95
The Ardunio is being powered by the USB connector.
The Relay Board has it's own 5V supply and is connected to the arduino by a digital line (for the pump) and the Vcc to Arduino 5V
I don't use the Arduino Vcc to power the relay board, it has it's own 5V supply into JDVcc (see below) schematic of the relay board:

There is a 12V power supply in the COM terminal, then the +ve lead of the pump is in NO.
The problem: When the 12V power supply is connected to the COM terminal the Arduino will freeze when trying to send a radio message (send) - even if the pump has not been activated and there is no 12V current flowing.
I have only seen this happen when I have an antenna on an extension wire connected to the LoRa transceiver. If there is no antenna, or a very short antenna with no extension wire I do not see this problem.
An antenna on a extension wire works no problem if I unplug the 12V supply from the relay board - even if the transformer is left plugged in within the project enclosure.
I am very confused by this.
Initially, I suspected there was some sort of power surge going on when the pump started (big motor) but I see this problem even if the pump never runs, all it takes is the 12V power supply be applied to the relay.
Is it possible that the 12V transformer is creating EM interference that's coupling onto a long antenna cable?
Thanks for any help.


texts: If a potentiometer is basically a voltage divider, why are they made in different values?

texts: I was taught that rheostats are current based devices, while potentiometers are voltage based. I can see why rhostats come in different values (eg making variable loads of different magnitudes), but why make potentioeters of various sizes if all pots of a given taper will return the same potential at, say, the 12 O'clock position? Or, given two points of different potentials, pots specify a point between the two. I never got very far in school, so I greatly appreciate your time and patience.


texts:
I've a PCB with repeated blocks. I made the design using rooms and coping from the source room to all the others. All work fine, from the the schematic using herarchical block to PCB. There is only a one thing I don't understand: is it possible to modify something in the master room (i.e. changing routing) and then have all the other rooms updated at once without re-copy and past them one by one?

I'm using Altium Designer 10. I attach some pictures of the Rooms tools I can use.

This is what I can choose from room menu.

This is what I can configure when I past a copy of a room.


texts: Representing an equation with a simulation of Operation amplifier adder

texts:
I am trying to represent an equation (Vf=-3V1+7V2+2) using operation amplifiers. The schematic that I did is:

simulate this circuit – Schematic created using CircuitLab

but I have troubles simulating it and doing it in reality. The problem is that when instead of putting two operation amplifiers, I put two source of voltage and its resistances like in V7, it gives me the correct answer, but when I put operation amplifiers, it gives an unwished answer

Using Op Amps

Not Using Op Amps

Have you got any idea why is this happening?, I believe that the equations are right because I obtain in both diagrams the input voltage that I want, but the problem is the output. I would appreciate any ideas you have, thanks in advance


texts:
We have a battery capacity tester (upto 30V battery & upto 25A discharge current) which when connected to a battery causes a heavy spark even in off condition (Control card supply off).
We have realised that there is some short circuit internally.
I opened the tester and saw a array of 2N3773 transistors connected in parallel as shown in the picture. I see this is the only possibility where it causing short circuit.

I am confused to see both incoming (from battery positive - fat red wire) & outgoing (to battery negative - fat black wire) wires are taken from collector (transistor body - as per the datasheet of 2N3773, body is collector).

How can it be possible?
Can anyone explain please?
Doesn't it cause shorting?

The circuit looks like this:


texts:
Today I started to get involved to the coordinate transformation especially the Alpha–beta transformation and Dqo transformation:

According to the wikipedia:
$$
\frac{2}{3}\begin{bmatrix} 1 & -\frac{1}{2} & -\frac{1}{2} \\
0 & -\frac{\sqrt{3}}{2} & \frac{\sqrt{3}}{2} \\
\frac{1}{2} & \frac{1}{2} & \frac{1}{2} \\
\end{bmatrix}
$$
this is the Clarke transformation, according to my teacher the transformation matrix is the following:
$$
\begin{bmatrix} 1 & -\frac{1}{2} & -\frac{1}{2} \\
0 & \frac{\sqrt{3}}{2} & -\frac{\sqrt{3}}{2} \\
\frac{1}{2} & \frac{1}{2} & \frac{1}{2} \\
\end{bmatrix}
$$
Which one is right?

I had made some test in Matlab from three axis I made a transformation to two axis, after that I made a transformation from alpha-beta to dq.
The result is:
$$
\begin{bmatrix}0.12 \\ 0.32 \\ 4\end{bmatrix}
$$
Afterwards I used the Park transformation, but the two result not equal.
The result is
$$
\begin{bmatrix}0.12 \\ -0.32 \\ 4\end{bmatrix}
$$
Also the Matlab is using the Park's transformation instead of dqo transformation, according the Wikipedia the Park's transformation is not power invariant, also I noticed that Vd is repleaced with Vq, Isn't it?

EDITED

Any three-phase sinusoidal set of quantities in the stator can
be transformed to an orthogonal reference frame by
$$
\frac{2}{3}\begin{bmatrix} \cos(δ) & \cos(δ - \frac{2\pi}{3}) &\cos(δ - \frac{4\pi}{3}) \\
\sin(δ) & \sin(δ - \frac{2\pi}{3}) &\sin(δ - \frac{4\pi}{3}) \\
\frac{1}{2} & \frac{1}{2} & \frac{1}{2} \\
\end{bmatrix}
$$
where δ is the angle of the orthogonal set a–b–0 with respect
to any arbitrary reference. If the a–b–0 axes are stationary and
the a axis is aligned with the stator a axis, then δ =0 at all
times, Thus
$$
\frac{2}{3}\begin{bmatrix} 1 & -\frac{1}{2} & -\frac{1}{2} \\
0 & \frac{\sqrt{3}}{2} & \frac{\sqrt{3}}{2} \\
\frac{1}{2} & \frac{1}{2} & \frac{1}{2} \\
\end{bmatrix}
$$

According to my calculation this have to be
$$
\frac{2}{3}\begin{bmatrix} 1 & -\frac{1}{2} & -\frac{1}{2} \\
0 & -\frac{\sqrt{3}}{2} & \frac{\sqrt{3}}{2} \\
\frac{1}{2} & \frac{1}{2} & \frac{1}{2} \\
\end{bmatrix}
$$

because the
$$
\sin(-\frac{2\pi}{3}) = -\frac{\sqrt{3}}{2}
$$

I found this example in the POWER ELECTRONICS HANDBOOK written by MUHAMMAD H. RASHID

Did I miss something on the math class?


texts: Finding load current in a circuit with voltage dependent voltage source

texts:
This question has been rolled back to the version that doesn't invalidate  the answers (edit by Andy aka)

I'm currently studying for my Circuit Analysis class, the teacher shared some questions and their answers with us, but not the steps of reaching the answers. I solved almost all of them, but whatever I try doesn't work for this question. Can you guide me, how can I reach the solution?
Teacher says the answer is \$I_L= 1,68 mA.\$
Edit: I tried Norton's theorem first since it asks for the load current, but I just can't get rid of the dependent source, I tried Thevenin and superposition as well but I can't seem to make it work. It's probably my bad, I'm doing something I shouldn't with the equations.
With Norton: I tried mesh analysis after shorting RL, and used supernode because there is IS in the middle of the meshes, but it doesn't work, I can't get rid of 2Va, using \$2V_a = 36i_1\$ doesn't work, since that leads me to \$i_2 = 3,648\$ which supposed to be my IL, but it's wrong, since the real answer is supposed to be 1,68 mA.
What I did was set clockwise i1 and i2. From supernode I got:
\$3,5 - 18i_1 - 7i_1 +2V_A = 0\\V_a = 18i_1\\3,5 -11i_1 = 0\\i_1=0,318\$
Then, IL is i2, so:
\$i_2 = i_1+3,3 = 3,648mA\$ which is wrong.


texts:
This is a simulation of a buck boost converter.  I want to get -12V as the
output voltage , but I get -1.148V.

I checked the PWM and the duty cycle and it is right.

I think that my problem in the hardware, but I can't understand
why.

Can you help me?


texts: Close a circuit at specific input frequency

texts:
I have several very simple circuits comprising of a battery connected to a LED. Additionally I have an input signal at some frequency, which I need to use in order to control these circuits. What I need is a switch for each circuit that closes it in response to a specific frequency in the input. For example, in response to a 100Hz input circuit A closes, and when switching to 120Hz circuit B closes (while A reopens).

I need it small and simple, please be gentle I'm a biologist.

Thanks!


texts:
I am making an electrical circuit for a school project, yet electrical engineering skills cease after Ohm's law :) Now I did some research but I find electric circuits harder to design than I had expected.
For the project, we need to control 6 12 V DC motors. We found that 4 of these motors need 1.2 A and 2 need 0.2 A. We control these motors with an Arduino, this Arduino needs 0.04 A. Motors and Arduino are powered separately by a 12 V DC transformer with max 5.83 A.
Since the motors need to rotate CW and CCW, a Dual H-Bridge DC Stepper Motor Driver - L298N is used and this driver drops the voltage by 2 V (from 12V input to 10 V output):
https://howtomechatronics.com/tutorials/arduino/arduino-dc-motor-control-tutorial-l298n-pwm-h-bridge/
The circuit I made is here:

Now my question is: Is this a viable circuit or have I overlooked / misunderstood something?
Thanks in advance!


texts:
What is offset in oscilloscope or what does it represent?

"The signals are shifted from the horizontal middle line of oscilloscope's display and this is because of offset's presence."

What does this mean?


texts: AT commands not working while serial is working as expected for HM-10

texts:
I'm trying to use AT commands through the Arduino serial monitor, however, it seems like the HM-10 module just acts as if it is normal data being added to the custom characteristic value.

I'm using the TX and RX pins on my Arduino Mega 2560, and I'm able to transmit via bluetooth and receive values via bluetooth. However, the problem is that I want the bluetooth module to interpret the data as commands.

This is my arduino code:

char c=' ';
boolean NL = true;

// the setup function runs once when you press reset or power the board
void setup() {
  Serial.begin(9600);
  Serial.print("Sketch:   ");   Serial.println(__FILE__);
  Serial.print("Uploaded: ");   Serial.println(__DATE__);
  Serial.println(" ");

  Serial1.begin(9600);
  Serial.println("Serial1 started at 9600");
}

// the loop function runs over and over again forever
void loop() {

  // Read from serial monitor and transmit to Bluetooth
  if (Serial.available()) {
    c = Serial.read();

    if (c!=10 & c!=13 ) {
      Serial1.write(c);
    }

    // Echo the user input to the main window.
    // If there is a new line print the ">" character.
    if (NL) { Serial.print("\r\n>");  NL = false; }
    Serial.write(c);
    if (c==10) { NL = true; }
  }

  // Read from Bluetooth and write to serial monitor
  if (Serial1.available()) {
    c = Serial1.read();
    Serial.write(c);
  }
}


texts: How does lamp lights up in synchronising unit?

texts:
I recently learnt about the synchronisation of alternators using Two bright and one dark lamp method. In this arrangement, lamps are connected between two sources. We done the practical using an alternator synchronising with the mains voltage 230v. Alternator was connected in star connection, well it was driven by a dc motor.

As I understand current flows back to the source, but in the real world because of the parasitic capacitance that will seems like a lie. But in the synchronisation, how does the lamps glow? how does the current flow between those two sources? The neutral point of the alternator wasn't connected to anywhere either.

I asked this Question before. Static-charges can flow to another but not in current electricity as I understand. We can't use two independent sources without having a common point there, so we always connect ground or negative in DC systems. How does this happen then?Is there something I missed?

I'm an electrical engineering student and I hope someone can provide me a good answer.

Thanks


texts: How can I read Thevenin voltage from such circuit in LTSPICE? I know how to get Thevenin resistance in LTSPICE. I calculated manually values that I expect to get from LTSPICE and indeed Thevenin resistance is almost the same.


texts: How to isolate battery AND PV with single pole switch

texts:
I have a battery powered microcontroller system which is charged by a solar panel via an LM317 fixed voltage regulator. It's simple, but works well; the PV is only 5W and the voltage is set to 16.4V ... battery is 16.8V Li-Ion.

When I ship the product to customers, or store on the shelf, it needs to be 100% powered down so that the battery stays full.
When the PV panel is plugged in but the box is not turned on, the system needs to be powered down so that it does not run.
I don't mind if the battery charges from the PV while the electronics are powered down, but it would be better (safer) if the charging system was also stopped when the button was off.
I need to be able to trim the LM317 to exactly 16.4V when the PV is plugged in and the battery is disconnected, during manufacturing, so I can't 'shut it down' to 1.25V by taking ADJ to GND when the battery is unplugged.

I have not yet found a way to do this with a single pole switch (it needs to be a small IP67 push button). Any ideas welcome! Here is my schematic so far. This option leaks ~1.8mA through the R23/24 network.


texts: Serial transceiver for PCIe is using Reference clock of 100MHz. Then how data transfer at the rate of 2.5 GTs is possible?


texts:
How much power loss in the coaxial cable? I transmitted a signal with 12dBm power and I connected through the coaxial cable to the oscilloscope. Cable Assembly Coaxial is RG-316 59.1" (1.5m) and DSAV084 digital signal analyzer/ oscilloscope. But I measured 12dBm power at the 4Ghz carrier frequency in the scope. For further processing, I need to connect the oscilloscope to another PC via ethernet cable. When I analyzed the signal in the software of that PC, I measured the output -4.52dBm

I think the cable loss is huge. Do you have any idea how I can minimize the loss in the cable?


texts: altium TI webbench, populate footprint in schematic

texts:
I have exported a design from Ti webbench in Altium format. I have used "project-component links" to link up the schematic and PCB.

The PCB has footprints set but the schematic does not which causes problems when generating the BoM. Using "update schematics" doesn't seem to push the footprints to the schematic. How can I get around this?


texts:
I have found a schematic explaining a LM317, principle of operation.
The way I read the diagram, the non- inverting op-amp input (+) is always going to be at the 'INPUT' level,
and doesn't matter what the adjust voltage is.
I am wondering if they should have a resistor where they have the circle for the adjust current. Lower voltage on adjust would then lower the voltage on the non- inverting input.


texts: What are these magnetic connectors called?

texts:
For a project, I am looking for a specific kind of magnetic connector. You can often find those on Apple products. It usually looks something like this:
AliExpress Magnetic Connector

The little pins are spring loaded I guess. The search for 'magnetic spring connector' seemed promising at first, but I still did not find much.
Does anyone know what these are called exactly or have a link to Digikey or Mouser?
Thanks in advance!


texts: How does a transformer increase voltage while decreasing the current?

texts:
Ohm's law states V=I*R.

That means when we increase voltage we must also increase the current(I.)

But transformer increases the current while decreasing the voltage or decreasing the current while increasing the voltage.

How does this happen?


texts: Is pulling current from Collector to Base allowed? (PNP transistor)

texts:
I am building a P-Mosfet gate driver and I have a question regarding the behavior of a PNP transistor connected in this way:

This circuit might look pointless, but it's a good representation of a stage, in which my totem pole driver can be locked for a longer period (this might be even used somewhere else, not just in this application).

I simulated this circuit in "falstad" simulator and built it using BC338 & BC327 transistors. It works quite good, the rise time for a 50nF capacitor is close to 400ns and without a capacitor - probably a few picofarads, because it's a breadboard about 100ns. The Mosfet that I want to drive has ~2nF of Gate capacitance.

This transistor is now connected like 2 diodes in parallel, but current prefers BC junction. I would like to know if the transistor won't get damaged in the long term by pulling current from Collector to Base, instead of, like it is supposed to - from Emitter to Base. In this circuit the current is relatively small, but if this connection is valid then maybe I might use it somewhere else.
Now the part of my circuit that does the Gate driving looks like this:

The Zener diode is required because I want the Mosfet to be quite fully turned on (10 volt drop will work fine on the whole VCC range, the Mosfet won't complain and at the same time I don't want to be near Vgs max values, the Vgs will be either a couple of millivolts or -10 volts).
Sw1 will be later replaced by a transistor of course, I don't expect higher frequency than 50kHz, maybe 100kHz. If it will work fine with the legendary UC3843 SMPS driver, then I will use it as a backup AGM battery charger.
Please excuse me my mistakes in English and Electronics, I am a beginner and to make matters worse not a native English speaker. Besides my question, if You find any mistakes in my design, then please let me know in the comments.


texts: Beginning with programming microcontrollers

texts:
I am a software developer (coming from Java and Javascript/web-app programming) and I'm very interested in programming microcontrollers like Arduino or Espruino. The problem is I have little to no knowledge about electronics. When it comes to circuit diagrams, etc., I have no idea what it means.
What do you recommend to get started with the basic electronics on a project level? I took a look at starter kits like the Fritzing Creator Kit. Would this be a good starting point? Or are there any other good starting point like a Youtube channel, blog, any good website...?


texts: Bi-Directional Logic Level converter 1.8V-5V using MOSFET

texts:
I need to connect an Event Detection pin (pin of the NXP NTAG 5 component) to a GPIO of the NXP i.XM6 processor.
The problem is that the NTAG 5 pin has a logic level of 5V and the GPIO has a logic level of 1.8V.
So my idea was to make a simple 1.8V-5V logic level bidirectional converter using a MOSFET.
How do you think I can do this?
Thanks for your help!
EDIT:
NTAG 5 boost datasheet


texts: LowPro proportional valve drive circuit clarification

texts:
Am new with amplifiers when trying to use them as a current controller so is just after some help in understanding the circuit.
I am designing a circuit that will use a LowPro Proportional Valve LowPro Proportional Valve Data Sheet and it comes with a recommended driving circuit. I will be running the circuit at 5V.
So I understand that the voltage at the +ve terminal will try match the-ve terminal so with a 5v input vin=5*(422/(422+4910))=0.395 V. This means that the voltage at the 1-ohm resistor will be 0.395 V, which will give a \$I_E\$ current of \$\dfrac{0.395}{1}=0.395A\$. Does this mean \$I_c\$ is approximately equal to 0.395A?
So this means that there will be 0.395 A running from Valve Drive Input to ground, which will give a voltage drop across valve coil of 10.1*0.395=3.99 V.
So would that mean that \$V_{CE} = supply - V_{coil}-V \ @1 ohm = 8-3.99-0.395=3.615\$?
I hope that was correct?
This is where I get stuck. The VBE(on) of TIP 120 is 2.5 V, which would mean the op-amp voltage is Vb=3.99+0.395+2.5 = 6.89 V (correct?)
If that value is correct does that mean there is a 1.11 V lost in the op-amp? due to it not being ideal? so Ib=6.89/1000=6.8 mA
TIP120 Datasheet
Also, the circuit supply voltage in the datasheet recommends 8 VDC, is this value for the op-amp supply and drive voltage or should it be 5 VDC?
Also couldn't you just use a MOSFET as a driving circuit instead?
Any advice on the workings of this circuit would be greatly appreciated.
Thanks


texts: Charging stage of Capacitor with AC source

texts:
First question: Can someone explain how a AC power source together with this topology can charge the capacitor? How does the process works?

how does the resonant charging behave in this topology?
How does the pulsing works via a transmission line transformer TLT?

Charging C1 (red, resonant charging C2 (blue) and transmision line transformer TLT (green)


texts: Do I need a decoupling cap for ICs that do not switch very fast?

texts: I am designing a space and cost constrained layout. On it I have two analog muxes (ADG719 (datasheet) or similar.) Both switch states a maximum of two times a second. They do carry video signals with a bandwidth of around 10 MHz, but they aren't amplifying those signals, just passing them. So I figure I can omit the 100n capacitor which is normally installed next to all the ICs on my board. Am I okay in doing so?


texts:
I recently came across a device (a headlamp) with lithium-polymer battery, which is marked 3.8 V nominal voltage, instead of usual 3.6-3.7 V. It's charging circuit is based on ME4057D chip, which is a 1 A lithium battery charger. The suffix -D in the chip's name indicates a variant which, according to the datashaeet, charges the battery to 4.34 V, instead of normal 4.2 V.

I would like to reuse this battery along with it's charging circuit in some of my projects, but I'm concerned about safety, because I always heard charging lithium batteries to voltage higher than 4.3 V can be dangerous.

Complete marking of the battery is: WT 902554 3.8V 1600mAh, but I didn't manage to get a datasheet.

My questions are:

Is the 3.8 V nominal voltage something really unusual, or there are some special types of lithium batteries, where such nominal voltage is normal?
Can be charging to 4.34 V dangerous or significantely decrease lifetime of the battery?


texts:
My question is will the following circuit work as an automatic pump control.
sorry for the terrible design.

if i connect the analogue pressure sensor in the primary connection in the circuit after a motorized pump,and the secondary sensor before the pump, and the motor leads between the motor and the mains ,will the following happen?

1-if the difference between the pressure at each side of the pump is lower than a pre-set value by pot 1(which means someone opened the tab), then the relay should close the circuit ,leading to the pump being run.
2-if the difference between the pressure at each side of the pump is higher than a pre-set value by pot 0(which means someone closed the tab), then the relay should open the circuit ,leading to the pump shutting off.

please don't flame me for a major design and just point it out.

If It Would Work can someone help me make a breaboard design.

i need to measure the difference between pressures as sometimes the water increases it's pressure or decreases it.
also thanks in advance and sorry for improper formatting and language,still new to the forum.


texts: Inverter Voltage Control - Stability Concerns

texts:
I have a voltage inverter that converts a 400VDC source into sine wave of 240VAC @ 50Hz. The inverter is based on a H-Bridge. The inverter works well but I'm struggling in understand how to control the output voltage incase the output rises or falls above the desired value (240VAC). The MCU driving the H-Bridge reads the output voltage via a step down transformer.

Will Proportional Control only work or do I need to implement PI? I was considering implementing something as follows: if actual voltage is less than desired voltage, increase duty cycle by 5%. Keep increasing the duty cycle by 5% till the output gets to 240VAC.

If the output voltage is higher than 240VAC, we decrease the duty cycle by 5% per iteration till we get to the desired output.

Is such a scheme likely to make the system unstable? Is there a better way to do this?


texts: Calculate ground fault current leak on human contact

texts:
I am sure this is very very simple and probably realy dumb but I've been banging my head for hours and can't figure this out. Or find an answer on google/books for that matter.

Even with the diagram on the right i can't figure this out. This is supposed to be a demonstration of the function of how and when an rcd trips. To simulate it we used an appliance (in this case a washing machine) that is not properly insulated and the person touching the chassis.

D is the insulation fault resistance, T is the earth conductor resistance, and H is the body resistance.

I want to calculate Id (leakage current), the contact voltage and Ih (current in the person).  Voltage and resistance values are given but I want to calculate the currents for multiple values.


texts: What could have caused this SMD capacitor failure?

texts:
I have an 0805 capacitor that has failed short circuit on a board. The maximum voltage it would see should be 16V. It has value 4.7uF, is rated to 25V and is X7R.
I don't understand why it might have failed.
Has anyone seen something like this before and would like to pass on their experience?
It could be physical damage, but then perhaps the damage seen below is from the current when short circuited.


texts:
I am working with an ATmega32-A microcontroller. Using USART communication, I am displaying data on monitor and am using switch case to select different commands. In one of the commands I have written the following code:

 case(DATA):

  init_io();
  statusreg = AD7798_8(0x40, 0xFF);
  printf("status register %02x\r\n", statusreg);

  if (statusreg != 0x80)
      printf("unexpected power on status %02x\r\n", statusreg);

  while(1){
            while ((statusreg & 0x80) != 0);                 // wait till ADC is ready
            adc = AD7798_16(0x58, 0xFFFF);                   // read register
            printf("ADC value is %04x\r\n", adc);
          }
  Command=0;
  break;

But the above code is printing the ADC value infinite times. I have changed the while loop to the following

   while(1){
            while ((statusreg & 0x80) != 0);                 // wait till ADC is ready
            adc = AD7798_16(0x58, 0xFFFF);                   // read register
            printf("ADC value is %04x\r\n", adc);
          }

After that it is printing only once, but does not accept any more commands. I have to re-build if I want to enter any other command. Any help appreciated.


texts: Indicate Heating, Burning and so on in Circuit Simulation Software

texts:
Is there have any simulation software which is indicating other than current signals like heating, burning and so on with time by Power. Circuit simulating like real world behaviors of circuit.

Component Heating or buring
Wire or Track Heating or burring

Have this feature in Proteus or Multisim software?


texts:
Trying to make a AC fan controller using Arduino and FET ST13005A. Instead of pwm with TRIAC or SSR, like to have fine control over the voltage. Voltage 230 V 50 Hz. Please see if the below simulated schematic is okay.

Circuit simulator link


texts: how to generate an analog output from a in-built pwm of Atmega 32AVR microcontrloller?

texts:
Please help me at how to generate a variable analog signal(0-5V) from a in-built AVR microcontroller's PWM(0-5V).
 I am doing a project on I-V data logger.I am using a MOSFET as variable load &  want to drive the gate voltage(Vgs) of MOSFET by a variable voltage which comes from pwm of microcontroller.
I would be very happy if somebody come up with answer.
Thanks in advance.

Nagu Bhanoth


texts: No voltage induced in secondary coil of transformer with 5V 1.5 kHz voltage from Wien bridge oscillator in primary coil

texts:
I have built a Wien bridge oscillator which outputs 5V at 1.5 kHz. When I hook up this output to the primary coil of a transformer I can't measure any voltage in the secondary coil.
Schematic:

simulate this circuit – Schematic created using CircuitLab
I thought that the problem might be a lack of current and therefore power in the primary coil. (How would I change that?)
How can I get a voltage induced in the secondary coil with this oscillator (or possibly another oscillator design?)


texts: I want to use below schematic to convert a single ended signal to a differential one. If I tie -Vs to GND the common mode voltage is +Vs. I used different +Vs values but the ADCs Vcm stays the same, why?


texts: How to calculate the pressure and velocity of an ionised gas that is being impelled with magnetic pressure

texts:
Calculating the velocity and pressure of an ionised gas based on magnetic pressure and magnetic force.
Questions:

Based on magnetic pressure expressed on an ionised gas, how do I calculate the current flow in amperes?

The magnetic field is rotating and thus the ionised gas inside the conductive & magnetic material (iron) expresses its flow as an alternating current.

Based on the magnetic force implied within the system, how do I calculate the speed at which the ionised gas flows throughout the system?

If it matters, the magnets that are not in rotation will change the current from AC-DC as it only allows one way flow like a diode.  How would the change in current types affect the pressure of the gas?


texts: Differences between the drive algorithms for BLDC, PMSM and IPMSM

texts:
In the manual for a Scott Drive motor controller, they have a parameter you can set, called Motor Type. Its description reads

The motor type determines the method used to calculate the reference Id, Iq
currents. The four supported motor types are Brushless DC (BLDC), Permanent Magnet
Synchronous Machine (PMSM), Interior Permanent Magnet Synchronous Machine
(IPMSM), and Induction.

I understand that Induction is the odd one from the group, as its drive algorithm is completely different. However I have a hard time assimilating the difference between the rest (since they are all permanent magnet machines).
Googling around I found:

BLDC is the one with trapezoidal back-emf, meaning simplified driving (it can be an AC square-wave)
PMSM has sinusoidal back-emf, so it needs sine-shaped drive
IPMSM is only different in that the magnets are buried in the rotor (for added strength). The back-emf should be sine (right?). As such I don't get how the drive algorithm differs from PMSM.

How is the drive algorithm different between PMSM and IPMSM? Is it only minor tuning constants?


texts: Should I touch the metal surface of my ESD wristband?

texts:
Most ESD wristbands have a little metal surface (something like 20mm*15mm) and a part of plastic or some sort of cloth that goes around the arm. Is it enough to touch the non-metal part or should I touch the metal part?

In other words: does the non-metal part of a ESD wristband conduct well enough to discharge me?


texts:
I built a simple non inverting op amp amplifier with 2 resistors and a TS972IN powered between 0-5V but my output was always set to 5V. I tried several others Op Amp, others resitors and I also moved my circuit elsewhere (I'm working with a breadboard) and none of this changed anything. In order to solve my issue, I decided to build something even simpler, a voltage follower but I have the same behavior, the output stays to 5V...

My circuit with the pinout I use:

simulate this circuit – Schematic created using CircuitLab


texts: CAN communication with the SM470R1B1M-HT microcontroller

texts:
I bought the IAR Kickstarter kit to work with the SM470R1B1M-HT (Texas Instruments) microcontroller. I would like to implement CAN communication between the microcontroller and a PC. I need to send commands from the PC and get some response from the controller.

I haven't seen any examples with CAN communication. How do I implement CAN communication in this microcontroller? Are there any tools which generate automatic code for CAN communication?

CAN document for SM470R1B1M-HT.


texts:
The circuit presented here is sized to switch 100W at a minimum pulse width matching 250Hz.  But actually it's currently only being asked to switch around 10-20W.  The load is an array of LEDs.  Q1 and Q2 also have small heat sinks on them for extra measure.

The input circuit actually includes one more BC557 (making the input active-low) and is driven by an Atmega328P PWM output @ 3.3V.

There are two of these circuits (two channels) in a single enclosure, driving remote LED lights.

The lights are part of a solar-powered lighting system, and the lights are often turned on during the day to regulate the charging voltage to the battery.

When this circuit works (which is normally the case) it works very well.

The problem is that occasionally the LEDs are jamming on, eventually draining the battery completely flat.

I'm pretty certain the problem is in this circuit (rather than code), because:

the condition appears physically very fragile.  Just opening the (normally sealed) enclosure seems to be enough to have the LEDs turn off - as does picking it up and shaking it!  Makes it hard to perform any circuit diagnostics!
But I can tell (wirelessly) that the Atmega has not rebooted.
And because both channels have the same fault, it makes me think it's a design flaw and not a component fault or bad connection.
Also, sticking my fingers all over the circuit (my quick test for high impedance circuitry) doesn't cause the LEDs to react.
And Q1 and Q2 don't appear to be very hot when in this condition, at least not after being in this condition for a fair amount of time - I've never caught it in the act...

On reflection, R3 could also be smaller.  But I find it hard to believe that's the problem either.

One possible mistake is the lack of a snubbing diode on the load, since the wire lengths are quite long.  But if that was the problem, would I expect to see it turning full-on?

Another mistake could be that I've undersized R1+R2 for suppressing some kind of oscillation?

Another mistake could be not allowing for some kind of thermal event's effect on Q1 and Q2?  Possibly exacerbated by being out in the sun?

I'm sure someone here can tell me what's going on :)


texts:
The university I study at has a special elevators for masters, and masters have somthing like a coin that they can use the elevator. As I know it's an rfid tag and  it is a 125khz one. and have a 100 turn coil.

My masters know that I want to do that, and there is no problem with doing this. Its something like a university project. I know that the tags have a special serial, and I can find one of that tags serial by using a RFID reader. However the current tags are not writable. Can I do this project by using a microcontroller? If so how? Also one of my friends is a specialist can he help me?


texts: What is the voltage of Vo in this circuit without a closed loop?

texts:
What is Vo?

My attempt is nothing more than a guess, and I'm not sure if I'm right:

I think Vo is 0 because current can only flow in a closed loop.  Since no current flows into the little "arm" from Vo to ground, the voltage across R2 is 0 and thus Vo = 0 volts.  Is this correct?

Also, would this mean that the node at the bottom of this circuit is grounded because Vo = 0? Or would it only be a virtual ground?


texts:
I am working with an FTDI "FT232R" IC [USB to UART conversion], and struggling to understand what the VIH spec of the IC is. I can only find reference to an 'Input switching threshold (VIN)' spec in the datasheet and that doesn't seem to change with VCCIO [IO voltage domain].

What is the relation b/w the 'input switching threshold' spec and the traditional 'VIH' spec?
Why wouldn't the VIN spec change with VCCIO?
If the UART i/f on my MCU operates on 2.4V, does the VIN of 1.5V max mean that I might be OK if the VOH of the MCU is > (1.5V +VHys)?


texts: Keep getting "Only input pin on net" error

texts:
I am doing ERC check and keep getting this error :

only input pins on net ADC7

that net is a pin from an mcu that has a name ADC7 but is not connected to anywhere and shouldn't be connected to anywhere .

So , what does the error means? can i ignore it ?

another warning i get is :

Missing junction in net x

where the net is just some pin that connected to vcc point .

What are junctions needed for? i have a connection, so if i move it i can see its connected, but there is no junction sign(green dot). is that a problem ?

Could you ignore these 2 errors ?

thanks .


texts: About SPICE: Should I use transient analysis or DC linear analysis?

texts:
My question is specifically linked to an exam problem where I had to find a function in terms of time for the current on a capacitor and a resistor. The circuit was very simple: A current time-variant current source in series with 2 subcircuits, each composed of a capacitor and a resistor connected in parallel. Please see the figure below:

So, if I want to simulate this circuit with a SPICE software, should I run a transient analysis, a DC linear analysis, or some other type of analysis?

If the current source was sinusoidal, I would use an AC analysis, but the current source runs a current numerically equivalent to t (in Amperes) where t is the time (in seconds) elapsed since the circuit started working.

Below I have written my netlist file. While it is not a valid SPICE netlist, it illustrates what I am trying to do, focus on the current source Iin:

CIRCUIT ANALYSIS
C2 0 2 20m
R2 0 2 3
Iin 0 1 {time}
R1 1 2 2
C1 1 2 50m

.TRAN 1us 100ms
.CONTROL
RUN
PLOT V(1)-V(2)
.ENDC

.END

If you tried to simulate this netlist, you would receive an error similar to the following (which I obtained using ngspice):

Original line no.: 4, new internal line no.: 5:
Undefined number [TIME]
Original line no.: 4, new internal line no.: 5:
Cannot compute substitute
 Copies=9 Evals=9 Placeholders=1 Symbols=0 Errors=2

How can I achieve this type of analysis?


texts:
My current understanding of the NMOS device is that if you apply a big enough potential difference to the gate relative to the p-type substrate \$V_{GB}\$, free electrons are going to appear near the surface of the substrate creating a channel that can potentially conduct a current if there is a non zero Drain-Source voltage. However, the equations  that describe the mosfet like \$V_{GS} > V_{T}\$ are considering the difference between the gate voltage and the source voltage.

My question :  Why those equations depend on \$V_{GS}\$ and not \$V_{GB}\$? Why the source voltage matters in creating this channel of electrons? Wouldn't it work if \$V_{GB} > V_{T}\$ and \$V_{GS} = 0\$ ? What I am missing?


texts: Hello I was wondering if anyone can help me with this 16 counter in multisim. What do I add to limit it at E rather than F? Thank you


texts: Controlling BLDC with IR 2130 - stuck at fault, unable to reset

texts:
I'm working right now with the following circuit, trying to drive the BLDC motor with it.

I don't exactly know how it works (especially the overcurrent sensing part) and the man that designed it is currently unreachable so I can't simply ask him.

I'm trying to drive the BLDC motor with it and Arduino but the IR2130 is stuck at FAULT state (so it's not sending any output to the transistors) and I can't reset it in any way.
I've tried resetting it by setting all LINs in high state for 10us as the datasheet says but it won't work. I'm monitoring the FAULT state before the main controling loop begins and I still get 0 at it. There shouldn't be any currents flowing through the motor right then so why would it detect any overcurrent? I don't think undervoltage is the problem because I'm getting nice and stable 12V at Vcc


texts: Will turning a device on and off via power supply hurt it?

texts:
I have an idea for a smart home set up, where I connect four electronic devices each into their own "smart" outlet, then use my phone to turn them all on at the same time with the touch of a button. It sounds cool, but I won't do it if there is any risks to the electronics. I suppose, in order for it to work I would have to leave the device "on" and then turn the smart socket on/off as desired.

Question: How safe is the above set up? Should I scrap the idea altogether, or should I proceed with some caveats in mind?

Further Clarifications:

Electronic devices: my stereo system which is comprised of a DAC, amplifier, subwoofer and equalizer, all are powered. (I love my system, but it's really annoying having to turn on everything)
Usage: I use it at least once a week (I know, I'm lazy and can't be bothered to labor over turning 4 devices on, even only once a week)
Smart Socket - Zigby (x4)

If necessary I can provide my exact stereo brands and model specs, but I thought I could pose this question for the general case.


texts:
I want to analyse a parallel LC circuit in terms of inputs and outputs as I am studying them in the context of using them as a tuned antenna.

However I am unsure of where to identify the inputs and outputs in order to find a transfer function between them.

Thinking of the mass on a spring analogy the input may be the applied force and the output is the displacement which becomes very large when the applied force nears the resonant frequency.

Is there some kind of equivalent for this circuit?


texts: How to make Altrium pan-scroll with mouse wheel?

texts:
I'm on the verge switching E-CAD from Proteus to Altium, so I'm trying out the evaulation version to see if we match.

One thing that I cannot cope with is the actions bound to the mouse wheel. In Proteus, I pan the view using mouse click (hold it to drag the views), while in Altium it seems to be bound to some sort of zoom.

Heading to Preferences->Mouse Wheel, I managed to get rid of the horizontal / vertical scroll using the wheel (I use it to zoom in/out instead, like in Proteus) but I cannot seem to understand how to make the pan scroll-behaviour like I want, since the fourth column is grayed out.

How can I make Altrium to pan-drag the view when the mouse wheel is pressed?


texts: How do I find the resistor values in this AC circuit?

texts:
One question from my college exam give to me this circuit, where the input is a
sinusoid with a 1V amplitude.

the question give to me a graph, frequency vs Amperies, that represent the current output value of resistor R1:

the first question is what's the nature of X? I think it's capacitive because the current increase with the frequency growing,in other words, the impedance of X decreases therefore X is a capacitor. But the second question get my mind blowing , it asks what's the values of R1 and R2.Could someone help me?? How do I find the R1 and R2 values from this AC circuit??


texts: How much binary data is transmitted across a physical wire in one clock cycle?

texts:
How much voltage change, what I'm calling binary data, can be transmitted over a wire at one time in one clock cycle?  I understand, I think, binary data is what we call it and the wire doesn't really send out a one or a zero.  It is conceptual.

I've been reading the question and have a measure of understanding, but not great.  I understand there is a frequency at which voltage is transmitted and represented by us visually/logically as binary data.  But how much "data" can be transmitted over a wire in one cycle?  Is one cycle one voltage transmission (a bit) across a physical wire?  Like Morse code but with computers it ends up being really, really fast (Ghz).


texts: Unable to get instrumentation amplifier to work correctly

texts:
I have built an instrumentation amplifier using an LM348N quad op amp, supplied with ±9V. A simulation of the circuit is done as in the link -
Simulation:

But when I connect the circuit accordingly, there is no variation in the output voltage as input is varied. The input differential voltage varies when I probe the non inverting terminals of the op amp, but I don't see any variation when I probe across the inverting terminals and the outputs of the op amps respectively. What am I doing wrong?


texts: What I would consider two basic facts about electricity are conflicting (to my understanding, obviously not in real life). I know it's said that a transformer provides isolation. I think I remember correctly, reading that the load on a circuit determines how much current is drawn from the source. So can a load on the secondary side determine current drawn from the primary side? It would seem not from the word "isolation", but I don't understand induction well enough to see why not I guess. Thank you for any answers.


texts: How to read a wider range of voltages into the SA ADC on a PSoC4?

texts:
I want to read in a larger range of voltages into the SA ADC on the PSoC4, however as stated on the data sheet for the ADC component the different modes can only allow a range of 0 to 2 - 3 V and I would like to extend the range to about 10V, is this possible? and how to go about doing so.

Edit - Is it possible to perhaps sacrifice precision for a wider range? the ADC will give a value up to 3 decimal points.

SA ADC datasheet


texts:
TL;DR : The output voltage from my 5V DC to 3.3V DC stepdown seems to output 4.5V DC - why?

Background:
I'm trying to power an Airport Express from USB rather than a wall outlet. I have discovered that the PSU inside the APE outputs 3.3V DC which powers the device. I figured I could rip the PSU out and replace it with a little board that steps the DC from 5 to 3.3, allowing my to use USB to power the APE.

So far I have cut the end off the USB cable and tested the red/black wires with my multimeter and can confirm it is outputting 5V DC. I then connected the red wire (5V) from the USB cable onto the VIN pin of the step down, and then tried testing the output voltage from the VIN by connecting the black lead of the multimeter to the ground wire (out of the USB lead), and the red lead of the multimeter to the OUT pin of the step down, its currently reporting 4.5V.

The step down device is one of these:
http://www.ebay.com.au/itm/281058278731?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Am I testing the output voltage incorrectly or is my step down faulty?

Where should I be placing the black lead of the multimeter to close the circuit in order to test the voltage correctly?

I can provide pictures if anything needs clarification.

Thanks!


texts:
I am trying to follow an instructable to use a teensy micro-controller board. At step 6 it tells me to select tweensy(USBKeyboard/Mouse) from the board menu. However, my board menu does not have this option, even though I have patched the Ardunio environment per the previous steps and I do see a lot of other teensy board options. Has anyone else seen this and found a fix.

The instructions do call for the Arduino 18 environment. I am usingArduino22, could this be the problem? I don't want to install two environments unless I have to.  Thanks for any help that you may offer.

James.


texts: No luck trying to make two XBees communicate in API mode with arduino XBee library.

texts:
I have been trying to make two XBees communicate for a long time. I have checked everything and at last I come here for some help from the experts or who have already stumbled upon the same problem as mine. I am using series 2 XBees.

I am using this library.

It's a pretty basic circuit.

The coordinator has a button and the router has LED. When I press button on coordinator, I send two bytes as payload to the router. The router checks if packet was received. If it was, it checks if the correct byte is received. If so, it turns on the LED. But, no matter what I do, I am not able to turn on the LED. I appreciate your help.

The code for the coordinator (sender):

#include <XBee.h>

// create the XBee object
XBee xbee = XBee();

uint8_t payload[] = { 0, 0 };

// SH + SL Address of receiving XBee
XBeeAddress64 addr64 = XBeeAddress64(0x0013a200, 0x408698be);
ZBTxRequest zbTx = ZBTxRequest(addr64, payload, sizeof(payload));
ZBTxStatusResponse txStatus = ZBTxStatusResponse();

int pin5 = 0;

void setup() {
  Serial.begin(9600);
  xbee.setSerial(Serial);
}

void loop() {
  payload[0] = 0x34;
  payload[1] = 0x76;

  if (digitalRead(7) == HIGH){
    xbee.send(zbTx);
    delay(1000);
  }
}

And the code for router (receiver) is:

#include <XBee.h>

XBee xbee = XBee();
XBeeResponse response = XBeeResponse();
// create reusable response objects for responses we expect to handle
ZBRxResponse rx = ZBRxResponse();
ModemStatusResponse msr = ModemStatusResponse();

void setup() {
  // start serial
  Serial.begin(9600);
  xbee.begin(Serial);
}

// continuously reads packets, looking for ZB Receive or Modem Status
void loop() {
    xbee.readPacket();
    if (xbee.getResponse().isAvailable()) {
      // got something
      if (xbee.getResponse().getApiId() == ZB_RX_RESPONSE) {
        // got a zb rx packet
        // now fill our zb rx class
        xbee.getResponse().getZBRxResponse(rx);
        // I check both bytes (or)
        if (rx.getData(0) == 0x34 || rx.getData(0) == 0x76 ) {
          digitalWrite(8, HIGH);
        }
      }
   }
}


texts: 130W fixture containing 160 RGB LEDs - what LEDs could they be?

texts:
I apologize for this very stupid question, but I'm diving head-first into electronics and I am sort of confused.  I'm hoping some experts' answers will at least give me more terminology, concepts, and electronics to look up and study (LOL).
What kind of RGB LEDs exist that you can combine 160 of them into a light fixture that runs at maximum 130 W?  All of the RGB (or RGBW) LEDs I see run at about 9-14 V per diode (like CREE XPE2 or XMLs, or even 5mm RGD LEDs), which makes sense because each LED generally about 3V it seems.  A 130 W fixture with 160 RGB LEDs means about 0.8W per LED...so with my limited understanding, what am I missing? (Again, I apologize for this kind of ignorant question.)
I'm not trying to build this light, I'm just trying to understand how you could combine 160 LEDs into a light that's rated by the manufacturer at 130W.  I am building my own light, but it's not a replica of this one...this is just a point of trying to understand RGB LEDs better.


texts:
I'm an electronics hobbyist and I have done a lot of electronics projects using launchpads like MSP430G2553, Arduino and Tiva C Series, so I never faced any problems to upload code to these microcontrollers.

But now for one of my projects I want to use an MSP430F6736 as it has features my project requires. But there is no launchpad with this microcontroller IC on the market.

So, I'm confused about how to use this microcontroller in my project. If I can manage to upload a blink sketch in to it I can do the entire project - but I have no idea how to upload code to such bare microcontrollers.

I have seen a lot of people using bare microcontrollers in their projects. Please help me.

Edit-

Thank you so much for your suggestions. I searched online after reading your solution and found ez430 emulator can be used to program most of MSP430 microcontrollers. I have a MSP430G2 launchpad and it turns out that it has ez430 emulator onboard which can be used to program and debug MSP430F6736 through SBWTDIO and SBWTCK pins.

For more info please refer this document.
http://www.ti.com/lit/pdf/slau647


texts:
There is no info available on the topic. Where should components be paced on the pcb board? Here is the screen from the datasheet of DRV8305.

Where should the 1uF capacitors on high side MOSFETs be placed?
Where should 470uF capacitors be placed? 0.1uF and 0.01uF?
1000pF caps from SN to SP?
SENSE devider resistors and the cap?

It is interesting to read about the logic of the placement also, why they should be placed there and not here.

Thank you!


texts:
I have some equipment that is mounted some distance from the front panel on the wrong side.  It has some flashing LEDs which are used to indicate whether the equipment is ready, in an error state etc.  I am looking for an off the shelf method for bringing the flashing light to the front panel.
 ___________________
|  ________         |
| |        |        |
| |________|        |
|    *   *          |   <- LEDs on the device
|                   |
|___________________|
                 * *    <- Where they should appear in the front panel

I had a look at the PCs - they have the LED just behind some clear perspex: not 30cm away on the wrong side.  All the cables are already the correct length so I can't shift the equipment.  I don't know if cutting the perspex with a handsaw would dull it too much.
I had a look at optical fibre - it is really thin and does not emit enough light.
Is there a simple way of bringing the flashing light to the front panel?


texts: Measure RF impedance of PCB or IC using a VNA Network Analyzer

texts:
I have a VNA and want to measure the impedance looking into my PCB.
My VNA is pretty old, it's a 8753ES.
My PCB includes a commercial Nordic or Dialog MCU with Bluetooth Low Energy (BLE). The path from the MCU includes bond wires, multiple transmission lines and parasitic components. I've analyzed what I expect the impedance to be using a Smith chart.
The path between the MCU and the antenna has been split and I can plug my VNA into the PCB or the antenna. The total distance from this location to the MCU < lambda/10. It's a single pin antenna.

Can I use a VNA to measure the impedance of the MCU?

If I put the MCU into constant transmit mode (as I have to?) then can I only match at one frequency? (BLE band is 2400MHz to 2480MHz)

Am I going to break my VNA if I plug a constant TX device into it?

I currently don't have the calibration tool and it costs $6K... For this exercise what is the consequence of no calibration? Can I make my own coarse calibrator?

To measure, connect the VNA to my split and simply look at the Smith chart? Only using one connector on the VNA. Can I look at the impedance radar (time domain response) to identify the effect of bond wires etc, or is the radar not straightforward?
Thanks so much!


texts: How to accurately measure 16MHz clock with Oscilloscope

texts:
I have a small problem trying to make a 16 MHz signal with a scope with 100 MHz 1 GS/s. I can't seem to be able to read the square wave from the MCU clock, see results on the attached picture.
I calibrated the probe with the 1 kHz built in square wave on the oscilloscope.
Also, I can see that if I output the clock signal with a prescaler of 5, i.e. a frequent of 3.2MHz  then I am able to read a signal that looks more like a square signal.
I'm not sure what I might be missing or doing wrong.
I'm using the STM Nucleo F410RB development board.


texts:
This potentiometer reads between 0 and 115K as I rotate the shaft. The wedged part of the shaft is 10mm.

Can anyone identify the part number?


texts:
In resource-constrained systems (like an 8-bit PIC), is there any benefit to using your own macros for true and false as opposed to using those defined from stdbool?

#define TRUE    (1)
#define FALSE   (0)

// OR (dummy example)
#include <stdbool.h>

bool IsThisGood(void)
{
  return true | false;
}

uint8_t IsThisBetter(void)
{
  return TRUE | FALSE;
}

How do they compare in terms of RAM usage? Stack usage? code portability?  Code simplicity?


texts: Troubleshooting why ADuM4160's internal regulator gives 5 V instead of 3.3 V

texts:
The problem I have with my ADuM4160 circuit is that I'm getting 5 V from VDD2 pin while getting roughly 3.3 V on pin VDD1. Have I blown the chip?

It doesn't make sense for the VDD2 to be the same voltage as what I am feeding to the VBUS pin, right? Could it be the bypass capacitors I am using? The datasheet says they should be low-ESR, but I'm unsure where to get them from. Most capacitors that I have found are SMD. I'm using cheap eBay-sourced ceramic capacitors.

The author of the circuit told me to check my supply for oscillations, but I'm unsure how. I do have a digital 40 MHz scope.

The only difference in my circuit is that the downlink is powered by my do-it-yourself LM338 power supply. Since my device has its own supply I don't need the switch-mode regulator.

BTW, the VDD1 and VDD2 are the outputs of internal regulators.

I'm testing this on a breadboard:

Here's an image of what I see on the VBUS2 pin which is coming from my LM338 PSU. I assume that this is normal and nothing to worry about, right? I don't see anything like the following when I turn up the volts per division. I can really see the oscillations when I turn the time base higher.
I see something similar on the VDD2 pin as well.


texts: Potential of the case of OS-CON capacitor

texts:
I am developing the board having through-hole OS-CON capacitors very close together up to them having a contact with each other. I recall that "regular" electrolytic capacitors may have potential on their case relative to the terminals (see this document from Nichicon, page 9 item 7). I have never experienced the issues because caps are usually put into the protective sleeve.

However OS-CON are not put into the sleeve, and nothing is mentioned in the product catalog.

Did you see any information or precautions regarding OS-CON family capacitor case potential? I can not find any relevant data in the device datasheet, product catalog, packaging, soldering and safety documents.


texts: The sign in the formula for the voltage across the inductor

texts:
This question is about voltage induced in a inductance.

I know the rate of change of current induces EMF in the inductor. The direction of the induced EMF will be opposite to the change that is causing it. The EMF induced is given by the following formula.

$$V_l = -L \frac{dI}{dt}$$

The negative sign indicates direction of induced emf across the coil is opposite the current change.

In the picture I have drawn current direction and \$V_l\$ direction.

If \$\dfrac{dI}{dt}\$ is postive, \$V_l\$ will be negative according to formula right? Or does the direction of \$V_l\$ has to be reversed?

In many Internet references I found \$V_l = L \dfrac{dI}{dt}\$. Which one is correct?

I hope they reversed \$V_l\$ reference points and removed the negative sign in the formula. Please clarify.


texts: How long could 4 series connected 18650 Li-ion batteries be used to produce a constant 14V 3A supply from a 14V 2Hz pulse train, before failing?

texts: How does switching from charging to discharging at high amperage affect the battery life? The batteries would be fed by the 2Hz pulse train whenever they were supplying power, so they would always be operating at a fully charged state.


texts: Does Fosc refer to the crystal frequency before or after PLL is applied for PIC18 microcontrollers?

texts: If I have a PIC18 microcontroller with an 8MHz crystal and 4xPLL, is Fosc 8MHz or 32MHz?


texts:
Well, it seems that static electricity has fried my LiPo balance plug adapter.
When I was plugging in my LiPo battery to it, which was plugged into my Thunder AC6 LiPo charger, a short wisp of smoke was created and the copper trace for the ground balance connection was damaged.

Pictures:

http://i.stack.imgur.com/gf5Ru.jpg
An overview of the balance adapter plug.

http://i.stack.imgur.com/waGTD.jpg
A closeup of the damaged connection.

Can I fix this, or would I have to buy another balance plug? If so, where should I buy one?


texts:
First time here, I'm having trouble at checking my solution in a task I got.

The task says that Vsource is 2 V when t < 0 and when T= ≥ 0 Vsource = 0.
The circuit it self built from one voltage source one resistor and one inductor. (R = 2 Ω, L = 10 μH.)

The thing is I try to simulate it as mentioned with the Vsource that it will start with 2 V and after t = 0+ it will drop to 0 V will appreciate any kind of help!


texts:
When making an astable circuit with a 555 timber, the frequency of pin 3s pulse is calculated using this:
f = 1.44 / (R1 + 2R2) x C
My question is why is 1.44 included.


texts: What is more accurate, thermistor's R-T table or Steinhart-Hart equation?

texts:
If I want the conversion of thermistor's resistance to temperature to be as accurate as possible, should I refer to a table or use the Steinhart-Hart Equation?

I am in doubt because a table contains many reference points and thus with interpolation you should be able to get an accurate result. On the other hand, by measuring resistance at 3 different temperatures, you get an approximate relationship between R and T for the exact unit you are going to use, and not a general set of data as is the case in a datasheet provided table. On the other hand, it is still just an approximation of a very nonlinear function. If thermistor tolerance is critical in answering this, I would assume a 1% tolerance.


texts: How can I stabilize unstable voltages over a silicon plate?

texts:
I've been working on an experiment where I investigate the hall effect over a circular silicon plate. Here is the schematic
The two channels of the oscope are placed between the plate. Each of the outputs are connected to the semiconductor via copper foil that connects to about a fourth of the disk with gaps between each connection. I'm expecting to see an increase in voltage when I place an electromagnet above the plate, but the problem is that the voltage across the plate keeps fluctuating between 100 mV- -50mV even when the magnet isn't there, so if the magnet is affecting the voltage I wouldn't be able to tell. I have an older ATX power supply connected to a boost buck converter supplying the 30Vs to the silicon plate. I'm measuring the voltage with an Analog Discovery Board 2. Is there something I should add to the circuit to stabilize the voltage or is it something to do with the nature of the silicon plate?


texts: How would one attach an optical fibre to a PCB for a display?

texts:
For a model train layout, I am looking to route a light to a difficult part of the layout - even the 1.6mm LEDs are too big for the area.  It is for display, not data communications.

One person has solved the problem on their layout using optical fibre, which seems quite sensible.  Rather ingeniously, the light is transferred from an LED the fibre via thimble with a hole drilled in the top.

The fibre does not need to be connected/disconnected from the PCB - a permanent connection is fine.

I am aware of solutions for POF in ethernet, but this is far beyond what I need.  I can't be the first one to have this problem since fibre optic trees are cheap and plentiful.

So, some questions:

If I have a surface mount LED (or an array thereof), how do I attach an optical fibre to transmit the light for this purpose? I assume there is some sort of plastic mounting I can purchase off-the-shelf.
What is the attachment called (i.e. does it have a standard name)?
How are they assembled? (e.g. manual, pick and place?)
What considerations are there in selecting the type of fibre to use? (it will be no longer than 1m)

(Note to moderators, "optical-fibre" would be a good new tag for this question)


texts: Options for wiring TTL camera to a Linux chip?

texts:
I'm a programmer that's a little out of his element here, and not sure where to start.

I'm trying to figure out a way I can connect this TTL camera to a PCB that also has a cheap ARM or DSP CPU on it. The ARM would be running some kind of headless Linux (probably Debian) with a homegrown device driver (I'd have to write it myself) that could read the serial video bitstream from the camera and do something with it.

So my constraints:

Cheap ARM/DSP processor that can run Linux
The camera (linked above)
Custom device driver (unless the camera comes with drivers, which the link doesn't indicate)
I'd prefer to spend less than $100 on the entire solution (camera, chip, board, etc.) --> cheap

Everywhere I look for an ARM chip, I get one of the following:

I have to buy in bulk (not an option; this is a hobby project); or
I have to buy a full MCU/SoC with lots of excess stuff that I don't need/want

Do I have any options here? I've been reading up on custom/DIY PCBs using this "toner transfer method" and it seems interesting. If it's possible, I'd be happy to design my own circuit, make my own PCB, and then attach a cheap standalone ARM chip to it (as well as the camera and anything else). But perhaps that's not an option; perhaps attaching a CPU to a homemade PCB isn't feasible for technical reasons.

My first preference would be to find a cheap CPU, solder it to my own homemade PCB, and do the same with the camera. Is this possible? If not, perhaps someone could explain why, and tell me what my options are?

Either way, I'm not real familiar with ARM. What's a good make/model that would suit my purposes? Thanks in advance.


texts:
There are some items that goes on the BOM that, in production, apear as 1 for many. Example: large card box to package 10 boards/products. These kinds of items apear on the BOM as less than one quantity. For the example above, it would be "0.1" boxes for each product unity.
Is there a way of overriding Altium's automatic "quantity" field that is based on the number of symbols of the same kind on the schematic and add a "less than one" quantity in the fashion described?

EDIT:
Since it seems to have caused confusion, I think my question may have been ambiguous. So I think I should add that this question is based on the principle that production methods can't be changed, thus the only purpose of the question is to know if there's a way to do this on Altium natively, nothing more.


texts: ouput voltage of power amplifier tda2030

texts: when the transistor push the current from their collector , voltage on pin 4 is affected by this current ? i mean it raise ? o remain dependent on gain  of amplifier that is 10


texts: hybrid-π model VS T-Model for MOSFET and BJT

texts:
1) when to use T model for MOSFETs instead of hybrid-π model?
2) when to use T model for BJT's instead of hybrid-π model?


texts:
First time here, so here I am with an electronic-related question. Please note that altough I have a scientific background, I'm quite new to electronics.
Setup
I'm trying to build a small audio amp using a LM386 chip. I found a lot of designs on different websites, and I ended up building this :

(source: free.fr)
The design is largely based on this one and this one. The cap between pins 1 and 8 sets a higher gain for the amp, and if I understood correctly, the feedback betweens pins 1 and 5 helps cutting higher frequencies and reducing hiss.
The input is a simple electret mic, and all this is powered by an Arduino board.
Problem
For my application of this amp, the microphone and the speaker are very close from each other, and I need a high gain. You might see the problem coming : I have to avoid the audio feedback (larsen) between them. This is why I added a simple RC low-pass filter at the end of the audio path (dotted box on the schematic). Its cutoff frequency is roughly around 1kHz, which should be ok because feedback yields frequencies higher than 4kHz.
This seems to be reducing the feedback a bit (I can put the mic and the speaker closer), but it isn't enough : I still get feedback at the same frequencies.
I tried to add a filter right after the mic output (before the amp), but then I can't hear any output signal in the speaker : it seems to be cutting all the input signal.
So, I'm looking for a filtering solution (either using extra components, or taking advantage of the LM386) that could help completely shutting off the highest frequencies of the signal.
I hope my setup and problem is clear. If not, do not hesitate to ask for more details !
Thank you !


texts: Instrumentation amplifier with frequency-dependent gain?

texts:
I have an AD8421 (instrumentation amplifier);  it has two pins to connect a resistor Rg that sets the gain --- G = 1 + 9.9k / Rg.  For example, a 100 ohms resistor produces a gain G = 1 + (9900 ohms / 100 ohms) = 1 + 99 = 100.

I need the amplifier to have a lower gain at DC;  to avoid additional stages or even a passive filter after the output, I wonder if I could use an R-C network where Rg is supposed to go, so that the "gain resistor" varies with frequency.  In particular, what about placing the following:

simulate this circuit – Schematic created using CircuitLab

With this, I get a gain of 10 at DC, and 100 at high frequencies, with transition being from approx. 1.6Hz to 16Hz.

Sounds like in theory it should work; is there any reason why it might not work in practice?  Any experience out there with this or similar setups?

Thanks,

Cal-linux


texts:
I have a laser printer that I've been wanting to use on the go in the car with an inverter.

The power consumption section in the printers manual:

Average operating mode    Less than 310W
Ready mode                Less than 30 W
Power save mode           Less than 1.2 W
Power off mode            Less than 0.45 W (0.1 Wc)

I bought a 500W inverter for the car thinking this would be adequate. I connect up the inverter and the printer, the printer turns on, and then just as it hits its warm up process the inverter trips and everything stops. My first thought is that the cars wiring doesn't like pulling ~500W through the cigarette lighter socket... even though the fuse didn't blow. I then connect it directly to the battery under the bonnet and the same thing happens. Out comes the multi meter, I set it to measure DC amps and connect it in series between the car battery and DC side of the inverter and press the power button on the printer watching it intensely for a spike just before it dies. As expected the multimeter reads something like ~7.3x.

Now, my question is, how many Watts is the printer using at this point in time?

is it 12V (input voltage) * 7.3A (input amps) = 87.6W
or is it 230V (output voltage) * 7.2A (input amps) = 1656W
or something else?

It seems right to multiply the volts and amps using measurements from one side of the inverter (1.) but it can't be using 86.4W otherwise I wouldn't have an issue. However, multiplying a measurement from one side of the inverter with a measurement from the other side (2.) doesn't seem right, but it's giving me an answer that seems more realistic to me.

Any clarification on the matter is gratefully received.


texts: AHT10 temperature and humidity sensor does not work anymore

texts:
I have used the AHT10 before, I liked it, it worked well. After that I bought new a AHT10 but it is not working with my Arduino. I am using this library.
I checked closly, and there is only one small difference.  The old board (the working one) has a 702 N (datasheet.) The new one has a K27 and not working (datasheet).
I am using these pins with an Arduino Nano:
VIN ----> 5v
GND ----> GND
SDA ----> A4
SCL ----> A5
When I use the new AHT10, the Arduino stops working. There is no printing on the serial monitor. If I remove the AHT10 from the  board it starts repeatedly printing this error:

AHT10 not connected or fail to load calibration coefficient

If I plug-in again the new AHT10, it stops to printing to the serial monitor and the Arduino does not work. If I remove the new AHT10 from board and plugin the old AHT10 it starts to work again. The old AHT10 starts to meausuring temperature and humidity.
What I sould I do? How can use this new AHT10?


texts: Overheating Linear Voltage Regulator In Lexicon Omega Audio Interface. Can I Swap With Reduced Amperage To Avoid Heat Probs?

texts:
I have a Lexicon Omega USB Audio Interface that's overheating.

Already tried several heatsinks, including the biggest one I could get (6"Hx2.5"Wx.5"D) with optimized cross-cut vertical fins, mica isolators, & prolimatech pk-1 cpu grease to help transfer.

Also replaced the LVRs to see if they had degraded with time, using TI parts to see if they would be better quality.

Still overheats & shuts itself off.

The 2 in question are the TI equivalents of an ON 7812CT and an ST L7912CV.

Not sure, but I think it may be the 7912CV because it's 1.5 Amp.

Since the power-input to this thing is 9V at 1.3mA = 11.7W,

And the 7812 is a +12V at 1.0A,

Is it crazy of me to think the 7912CV (-12V, 1.5A) could just be swapped for the 1.0A version of that one?

Something like an ON MC7912CTGOS-ND which is -12V at 1.0A?

-You know, without destroying the unit, causing fires, tsunamis, reflowed Microsoft Word Docs, etc.

Sorry, but I don't know much about electrical engineering at all.

Lexicon seems to have made an absolute lemon here. Converts from AC to DC inside the box with no OEM heatsinks or case-vents of any kind.

Another reason I ask about the LVR swap, is I hesitate to cut/drill the case & would like to avoid it if possible.

Thank You Very Much for any Time, Attention, or Help!

-Will

PS: Error-behavior is that it cuts out after playing a few hours of pink noise & the internal "circuit breaker" trips, along with a power-fluctuation of everything else on that outlet.

PPS: The other transistor on that side of the board is a TIP122 which barely gets warm at-all. It's the 2 LVRs that are constantly on "barbecue mode".


texts:
I was trying to power a transimpedance amplifier built with an op-amp on a protoboard.

I only had a power supply that looked like the first image below (no COM, which I would have connected to GND of the op amp).

The answers I got for my initial question posted on this website were really good and perfectly explained what I was supposed to do. (I initially asked questions about different kinds of power supplies)

I made a mistake of connecting the mains earth of the power supply (circled in the first image below) to the + pin of the op-amp, where GND (COM of a power supply) was supposed to go.  I understand why I was not supposed to do it. The mains earth is ill-defined since it is disconnected from both positive and negative voltage outputs of the power supply.

It seems I broke my op-amp when I connected the mains earth to + pin of the op-amp where GND (so COM) was supposed to go. I see that I was not supposed to do it.

My question is how did I brake the op-amp by connecting the mains earth to the + pin of the op amp?


texts: How will equivalent EMF and resistance of cells be calculated

texts:
In the image, three cells are arranged in a circuit. But the cell in the centre is installed such that the positive terminal is connected to the positive terminal of one cell and the negative terminal is connected to the negative terminal of the other cell.

What does this mean for the total EMF and resistance of the cells?

I speculate that the total EMF and resistance will be calculated as though the centre cell were connected in parallel to the other two. Assuming each cell has an EMF of 1.5 V and constant internal resistance of 2 ohms, this would give a total resistance of 4/3 ohms.

As for the equivalent EMF, I speculate the EMF for the centre cell would be -1.5 V and then the total EMF would be +1.5 V. Is this calculation correct?


texts: When current flows from a battery, does voltage decrease?

texts:
I understand voltage to be a potential for electrons to be pushed through a circuit.

However, in a battery, you have an electron build-up that creates the voltage. Once current begins to flow, electrons are now moving through the circuit.

Does this mean that the voltage actually begins to decrease as a direct result of current flow? Specifically are electrons "used up" or do they simply lose energy (dissipated as heat in circuit) which leads to a lower voltage potential?
Or another scenario, do the electrons, upon returning to the battery, still act as voltage potential to continue to push a consistent amount of current through a circuit despite the loss of energy?

Or is there something else I'm missing entirely?

Thanks.


texts:
I am trying to use a STMicroelectronics L7805CV to increase voltage from 7.5v to about 12v, but I can't get it work. I've placed 470 ohm resistors between out and common and between common and ground, which should give me about 10v, but instead it only gives about 7.5v. It's like the 7805 can't handle any higher, when I put a second 7805 in parallel, the voltage rises to 8v.

I've made the following observations:

100 ohm resistor between out and common, commond connected to ground; The voltage is a nice 5.0v.
470 ohm resistor between out and commond, common connected to ground; the voltage drops to around 3v, this I find very strange. The load is lower so it should be easy to maintain 5v?
100 ohm resistor between out and common, and a 100 ohm
resistor between common and ground; the voltage is around 8v.
470 ohm resistor between out and common, and a 470 ohm
resistor between common and ground, the voltage is around 7.5v.

My setup is similar to http://www.rason.org/Projects/regulator/regulator.htm

Any ideas on why this isn't working? According to the datasheet, you can use the device this way.

Thanks in advance!

edit:
If you're reading this and are trying the same. This is not the way, try this: Step up DC/DC 5V -> 6V


texts: Controlling 2 relays with 1 Open-Collector output

texts: I had a board with open/collector output pins, and i need to control 2 relays syncronioulsy (open and close at the same time) with 1 open collector output. So how can make the connectıon from pin to relays?


texts: Drive IRFZ44N Mosfet with 2N2222 NPN Transistor from ESP8266

texts:
I have made a circuit which controls 12v led from ESP8266. Led is being switched from IRFZ44N Mosfet. To convert logic from 3.3v to 5v, I used 2N2222 transistor. So my overall circuit looks like this:-

This circuit is working fine except on writing ESP pin HIGH, led turns off and on writing gpio LOW, led turns on. This is problematic because on resetting ESP, led stays on until code reaches the turning gpio HIGH. Please suggest me a solution for this. I know its a dumb question but I can no where find related question, that's why I asked a fresh one.


texts: MCU HIB pin only pulls Buck/Boost EN pin every-other Hibernation

texts:
MCU: TM4C1294NCPDT

Buck/Boost Converter: TPS63051

Hib dedicated LDO: MIC5504-3.3YM5-TR

I have a LiPo battery coming into the board, feeding both the TPS63051 and the MIC5504. Tiva's HIB pin is connected to the TPS63051 EN pin (Active High). When Tiva goes into Hibernate, HIB pin is pulled low. This should disable the TPS63051. However, it only does this exactly every-other-time. The MIC5504 should always be on, to provide power to the HIB module (plus RTCC.)

I have an LED connected to the +3v3 output of the TPS (for indicating that it's on) and one connected to an MCU output pin (which should shut off during hibernate)

Here's how it looks:
Multimeter on HIB pin, plug in LiPo:

HIB High @ +3.331V
MCU hits hibernation
HIB Low @ 0.01V
All LEDs dim (should be off...)
Hibernation ends, LEDs are full brightness, HIB is back to +3.331V
MCU hits hibernation
HIB Low @ 0.01V
All LEDs fully off

Rinse, repeat.

When the LEDs only partially dim, the TPS63051 output reads +2.195V...

I'm stumped. What's going on?!

Here's the relevant parts of the schematic. Note: The LiPo battery connects to a (not shown) BQ24232 Battery Charger IC, which provides VSYS to the Buck/Boost Converter and the Bat. LDO Regulator.


texts: Using a small Li-Po as a backup power source for a model

texts:
I am building a model of a trolleytruck (similar to a trolleybus but with a truck) and I'm adding an Arduino to get data. The microcontroller should never lose power because it would restart. I was planning to add a small Li-po battery to supply power to the microcontroller when the truck is not getting power from the lines (in case of some oxide forming on the wires or anything else).

Both the Arduino and the motor can be powered with 3.7v, so a 1S battery would be ok.

Is there anything that I can buy that manages the charging and discharging of the battery? Will the battery get damaged because of those quick intermitent charges and discharges?

Thanks for all and sorry for my bad English.


texts: How to Create a Simple Speaker Driver After LMC555 with Low Pass Filter

texts:
I created a very basic sound generator which ends in a LMC555 which plays a melody in the frequency range between 440Hz-880Hz. Now I struggle with the speaker driver. I would like to use very basic components like transistors and MOSFETs and no sophisticated IC.

The current circuit looks like this. I omitted the whole melody generating part. It uses MOSFETs to change the frequency of the LM555 as shown.

simulate this circuit – Schematic created using CircuitLab

The current solution is not ideal. But I struggle to bring the output signal from the LM555 into a signal which can be filtered using a simple RC low-pass filter so it can be used to be amplified using a transistor, or even be suitable to as input for an amplifier.

I looked through many examples, but they usually just connect the speaker directly to the LM555 without transforming the signal first. So the output will be still a very extreme square wave.

How could I implement a driver like this?


texts: How to successfully trigger an ILA core in Vivado

texts:
I am trying to debug my VHDL project in Vivado 2014.03 on a KC705.

My project consists of multiple VHDL modules implemented as custom IP cores, which are connected in a block design.

I selected mark debug on the signals that are connected to the ILA core.

After synthesis I used setup debug and added the nets that my ILA core is analyzing. The .xdc file was modified and I even resynthesized the project just incase...

After writing the resultant binary file onto the FPGA, I get two ILA cores, both of which get stuck at "waiting for trigger". Sometimes my ILA cores responded to trigger immediate, but they always return the same result and it isn't useful because the time window that I need is quite short.

I mapped one of the signals to an LED and confirmed that the signal exists.

I also synthesized the entire project in pure VHDL without using any custom IP cores. Again - I had the same problems.

I would like to make smart moves while debugging this issue, because each synthesis takes about two hours and it is very easy to make the project go out of date.

What could I be doing wrong? What can I try next?


texts: Use step-down 1.3-35V converter together with a step-up 5-24V converter

texts:
I want to build a variable power supply.

I am using a computer power supply and I want to make the 5 volt 20A output variable.

I found an online website that has all the components that I need. But I have a problem. The step-down and step-up converter output different voltages. The step-down outputs 1.3-35V and the step-up outputs 5-24V. Can I use them even though they are different?

My power supply outputs 3.3V, 5V and 12V:

3.3V output 14A MAX

5V output 20A MAX

12V output 10A MAX

I want to select the 5 volt output and attach the converters there.These converters can output 2A max

I want it to be variable from 2-24Volts. Or at least from 5-24Volts


texts:
As I game on my xbox on the same screen I have connected my pc, sound is a problem as I only have one set of speakers/headset. Please look at my simple design how how Im thinking of solving the problem:

Im thinking of tuning the volume of the xbox and pc at the same level, say 80% of max and then tune it down with the pot in the diagram.

What you guys think? Would it work?