texts: Does this type of amplifier, IC or component exist?

texts:
I am developing a circuit that has as an input a line-level audio signal, it then boosts the signal using either an op amp or transistor so that line-level (which is around 1.6v) is boosted to what my MCU ADC input works best with, which is 3.3v

The problem I am trying to solve, is that the audio input signal will come from a phone, ipod or what ever, and each of these devices has its own volume control. But the end result I want is not related to the volume, I just want to have a signal that is optimally amplified what ever the volume.

Is there an IC that does this, or a circuit that can make this happen? I have ideas on what to do in the digital realm through code, but it would likely produce better results if I could solve the problem on the analogue side.


texts:
I'm new to embedded and I've been struggling with this for days. I just don't understand why this doesn't work.

I'm using an ATxMega128A1. I want to use a timer overflow interrupt to left shift a bit on a port to the next pin. The timer works. I can see it click through CNT in the simulator, and the overflow flag gets set, but the ISR never executes (and thus, the overflow flag never gets reset either). Does anyone have any idea where I'm going wrong? I more or less copy/pasted the timer/interrupt code from Atmel's training code.

ISR(TCC0_OVF_vect)
{
    LEDPORT = (LEDPORT << 1);
}

int main(void)
{
    initLights();

    // Set up Timer/Counter 0.
    TCC0.PER = 0x10; //
    TCC0.CTRLA = ( TCC0.CTRLA & ~TC0_CLKSEL_gm ) | TC_CLKSEL_DIV1_gc; //start timer with system clock
    TCC0.INTCTRLA = ( TCC0.INTCTRLA & ~TC0_OVFINTLVL_gm ) | TC_OVFINTLVL_LO_gc; // Enable overflow interrupt.

    // enable global interrupts:
    sei();

    while(true)
    {
        //do nothing, the timer interrupt will handle it
    }
}


texts: Analysis of a Bi-directional DC-DC converter

texts:
I'm building a bi-directional DC-DC converter that will be used to charge and discharge a supercapacitor stack. The design we came up with uses a 4-quadrant chopper, to allow buck-boost both ways. I've made a design in PSIM which can be seen here:

I'm having a bit of trouble with correctly predicting the simulations behaviour. For instance, if Q1 is open, Q2 and Q3 are closed and Q4 is Active (A). Then the circuit becomes a boost converter from the left to the right side (Fuel Cell->BoostCaps), with a purely capacitive load. I want to boost the FC voltage, which is set to 24V, to the voltage of the BC, lets say 30V. Since the output voltage always equals the BC voltage, regardless of duty cycle, i want to be able to control the amout of current going towards the BC.

I've tried rewriting the state equations for a boost converter, but still don't seem to be getting a good result. For reference, if the FC voltage is 24V and the BC's is 30V, then a duty cycle of 0.03 on Q4 corresponds to a load current of around 1A. While my calculations say this should be at least 0.11.

I would really like some help with finding a way to make a mathematical model so a controller can be implemented. A link to a paper or book would be welcome too!

Some clarification:

In the schematic, the "BoostCaps" are the supercapacitor stack.
The voltage source and resistor on the left side simulate the Fuel Cell. You are correct that it does only generate power. The diode is to prevent back current into the fuel cell.
For simplicity in this simulation i used the voltage controlled current source on the right (the diamond thing) as a constant load. (in reality it will be a 3-phase brushless motor + controller.)
Don't mind the triangular thing, it's not taken into account here.
The converter is full-bridge because we aren't certain yet on the supercapacitor stack voltage. Can be either higher or lower than the FC voltage of 24V, hence the full-bridge.
Bi-directional because the supercaps act as an energy buffer. If the load current is low, the supercaps can be charged. If the load current is high, the supercaps provide some extra current to support the fuel cell.

[edit] and this is the topology:


texts: Ferrite bead isolation for FPGA core voltage

texts:
Why is the ferrite bead isolation not recommended for any FPGA core voltages.
When we usually refer any FPGA schematics the voltages output from regulators are directly connect to FPGA without any series isolation between regulator output and FPGA IC pins.


texts:
I need a current transformer for an induction heating project. After searching Digi-Key for a transformer meeting my specifications (turns ratio, current, mounting type, etc.), the cheapest model I found was this. Unfortunately it specifies a frequency range of 50 kHz to 500 kHz, whereas my induction heater works at frequencies as low as 20 kHz. I simply couldn't find any other model that meets my specs (especially with regards to mounting) on Digi-Key.

Now, in principle I would avoid using a part outside spec, but due to lack of options, I've been trying to find out what sets this lower limit of 50 kHz for the frequency of this particular part, hoping that some particularity of my application would mean I could indeed use it at lower frequencies.

One of the answers to this question (by Spehro Pefhany) mentions the \$L/R\$ constant for the secondary. For my application, I selected a burden resistor of 3.3Ω, which along with the stated inductance of 22.4 mH, works out to a 6.8 ms time constant, therefore a 23.4 Hz cutoff frequency. Even if it were necessary to take the CT's secondary resistance of 2.9Ω into account, the cutoff frequency would approximately double. Either way, the attenuation at 20 kHz should be negligible. This doesn't seem to be the limiting factor.

The datasheet notes that the peak flux density should remain below 2,000 Gauss, and an equation is given to compute this:

$$
B_{PK} = \frac{8 \times V_{REF} \times d \times 10^5}{N \times f}
$$

Where \$V_{REF}\$ is the voltage applied to the burden resistor, \$d\$ is the duty cycle, \$N\$ is the turns ratio, and \$f\$ is the frequency in kHz. Plugging in all values for my application, I get \$B_{PK} < 1000\$ Gauss, worst case (including some added margin). So this doesn't seem to be the limiting factor either.

Therefore I ask: does anyone have a plausible theory why this current transformer shouldn't work for 20 kHz signals?

By the way: should I be worried about the fact that my current, although switched at 20+ kHz, has a 120 Hz component (due to the mains frequency)? My gut feeling is that it doesn't matter, but I'd thought I'd ask nevertheless.

Edit: as per a commenter's request, this is the datasheet for the CT. Regarding the waveform, it can be approximately described as a 20+ kHz sine wave multiplied by a 60 Hz full-wave rectified sine wave. I've sketched the waveform in the figure below, however I used a 2.4 kHz waveform in place of the 20 kHz waveform, because with the full 20 kHz waveform the plot became unreadable.


texts:
I am trying to make a fourth order passive RC low pass filter. I simulate it in Multisim but find that the filter creates THD. And the higher the order of the filter, the larger the THD. I can`t figure out why.
Here is the schematic:

simulate this circuit – Schematic created using CircuitLab


texts:
I've got a 4 year old LG TV remote control, which I recently took apart.

I've also got a Popcorn Hour A-100, without the original remote.

So my question is - given that I don't care about the plastic packaging - is basically how to transform the old TV remote into the NMT (Networked Media Tank) remote which I require.

I'll divy it up into 3 seperate questions:

Is there a way of finding out which IR signals are required to operate a specific device, namely my NMT?
Is there a way of finding out which IR signals a remote puts out, with the push of every different button (or am I approaching this all wrong, and the push of a specific button does not trigger a different IR signal,but merely sends the information to the micro-processor which in it's turn tells the IR signaler what to do) ?
Lastly, is there a way to re-calibrate a remote so it puts out the IR signals I require?


texts: Gas discharge tube datasheet impulse sparkover specification

texts:
What does the Impulse Sparkover at 100 V/us and 1000 V/us mean?

Does it have anything to do with arcing?

How does the impulse help us decide with which GDT to choose?


texts:
I need to find a small motor (max 10W) with a high torque(max 1Nm) and low rpm(max 60rpm).

This question has been asked several time but I still have some doubts.

I understand that the best option is to use a gearbox.
The reason why find this motors is quite hard is explained in this
question:

  You can play with all three of these variables, but there are definite
  limits on how much field intensity you can get with reasonable
  materials. Therefore, you end up needing either a long motor or a
  large-diameter motor, both of which require lots of extra (expensive)
  material to produce.

My questions refers to same applications in particular gimbal and robots. In this products is there a gearbox?

In particular the gimbal, I can't figure out how the manufacturer can put a gearbox in such small object considering also the axial and radial loads apply directly on the gears. I find also that there is a particular kind of motor called gimbal motor that should provide high torque and low rpm. Is there another type of motor or is it equal to normal BLDC motors?

The same problem is related to the robot. What kind of gearboxes do they use (if they use)?


texts:
My Dell laptop (Inspiron 15 7559) has a dead AO7400A MOSFET, and I've been looking all over for a replacement, but with no luck. Does anyone know an equivalent to it, or maybe somewhere I would be able to find one?

If I were to find one that is not for my specific laptop model, but a generic AO7400A, what are the chances of it working? Because I assume if it has the same name there probably aren't that many variations of it, or am I wrong to assume that?

Any information about it would be welcome.


texts: Shapes getting distorted while displaying in LCD

texts:
I am trying to display a circle in my 800*480 LCD (TIANMA). But an oval shape is getting displayed instead of circle.
The length of LCD is 15.5 cm. Assuming square pixels length to breadth ratio should be 800/480. From this I got breadth as 9.3 cm but actual breadth is 8.3 cm.

Is it because of this problem the figure is getting distorted.

I have tried with Ampire LCD (640*480) with length breadth of same ratio.
It is displaying exact dimensions.


texts: Cut Off mode of an NPN transistor with PSPICE

texts:
]2

I am trying to model the cutoff mode of an NPN transistor with a switch that is connected to the base. Unfortunately, it shows current going through. I am using ORCAD Capture.

Does anyone know how to fix this? I should see zero current from the connector to the emitter.

I really don't know how the switch works in PSPICE. From what I found on the internet the symbol means that it opens at time t. Where should I define the time t? I googled and couldn't find an answer. The name of the switch is sw_tOpen and can be found in ANL_MISC library.


texts:
I found this strange thing upon my textbook

as an exercise to "comment by its truth table".

so I did the gargantuan truth table

But there's nothing to "comment", as I see.

The s2 = y0 reacts as a XOR or XNOR gate depending on x2, the c3 = y2 as an AND gate and the s3 = y1 seems entirely out of place.

Am Ι shortsighted at this?

Is there a connection in this design?


texts: PIC16F18877: Using I2C to read sensor (LSM9DS0) value

texts:
Every time I go through the code step-by-step in debug mode, I end up having the same value in SSP1BUF even after changing the orientation of the sensor.

I send slave address with write bit.
I send slave sub address.
I send slave address with read bit.
Output the received value in PORTB.

I am probably going wrong somewhere in the last 10-15 lines of code. Please have a look.
Thanks!

#include <xc.h>

#define _XTAL_FREQ 32000000

void main(void)
{

    TRISC = 0x18; // Set RC3(SCL) and RC4(SDA) as inputs.
    ANSELC = 0;   // In debug mode I can see RC3 and RC4 high after stepping into
                  // this line of code, so I know SDA and SCL are properly pulled
                  // high.
    TRISB = 0;    // Saving received I2C data in PORTB.
    ANSELB = 0;   // After this step the PORTB is filled with the last
                  // SSPBUF data (0X3D), I find this weird

 RC3PPS = 0X14;   //
 RC4PPS = 0X15;   // Setting RC3 and RC4 as SCL and SDA pins
 SSP1CON1 = 0X28; // SSPEN - 1, SSPM - 1000
 SSP1ADD = 0X03; // clock frequency 31.25 kHz
 SSP1STAT = 0X80; // SMP - 1

 // First write with slave address
 SSP1CON2bits.SEN = 1;  // Start I2C

 while (SSP1CON2bits.SEN == 1); // Wait for "START" to finish
 PIR3bits.SSP1IF = 0;
 SSP1BUF = 0X3C;                // LSM9DS0 Accelerometer address(with write bit)
                                // Page 33 in LSM9DS0 data sheet
 while((PIR3bits.SSP1IF == 0) && (SSP1STATbits.BF == 1) && (SSP1STATbits.R_nW == 1));
 PIR3bits.SSP1IF = 0;           // Wait for transmission to complete

 // Slave sub Address
 SSP1BUF = 0X2C;                // sub-address of Z-axis acceleration data
                                // register, first 8 bits
 while((PIR3bits.SSP1IF == 0) && (SSP1STATbits.BF == 1) && (SSP1STATbits.R_nW == 1));
 PIR3bits.SSP1IF = 0;           // Wait for transmission to complete

 // Repeated Start
 SSP1CON2bits.RSEN = 1;        // Repeated Start so that I can start reading the
                               // above Z axis data
 while (SSP1CON2bits.RSEN == 1);/* Wait if Transmit in progress */
 PIR3bits.SSP1IF = 0;
 SSP1BUF = 0X3D;               // LSM9DS0 Accelerometer address(with read bit)
                                // Page 33 in LSM9DS0 data sheet
 while((PIR3bits.SSP1IF == 0) && (SSP1STATbits.BF == 1) && (SSP1STATbits.R_nW == 1));
 PIR3bits.SSP1IF = 0;          // Wait for transmission to complete

 SSP1CON2bits.RCEN = 1;        // Enable receive in I2C
 //while ( SSP1CON2bits.RCEN == 1);
 while(SSP1STATbits.BF == 0);
 PIR3bits.SSP1IF = 0;
 PORTB = SSP1BUF;

 SSP1CON2bits.ACKDT = 1;
 SSP1CON2bits.ACKEN = 1;
 while( SSP1CON2bits.ACKEN == 1);
 PIR3bits.SSP1IF = 0;

 SSP1CON2bits.PEN = 1;
 while(1);

}


texts: Can I power a LED controller (Pixlite 4) with a 5V 30amp power supply

texts:
I bought a pixlite 4, LEDs(5V) and a 40A-5V PSU.
I have 2 questions:
1- I dont't want to cause any damage to the controller and I'm wondering if I can connect my PSU straight to the controller. (the manual says that the controller is limited to 30amps and my PSU provides 40amps)
2- Can I do the same a Q1 above with my LEDs, 5m of strip needs 9amps without blowing out the LEDS ?
Controler user manual: https://www.advateklights.com/downloads/user-manuals/pixlite-4-mk2
Thanks in advance! :)


texts: Why are RF components and cables still so large?

texts:
With the advent of ICs in past decades, circuits have decreased in size exponentially over time. However, it appears RF components and connections, with coax SMA cable, connectors, and components, like the one below, are still hefty and large:

Why have they not shrunk? Why can't coax, as you see on the side of the this amplifier, be decreased in dimensions?


texts: Voltage gradient across an antenna (and how it drives an AM radio)

texts:
Edit:
I was interested how is voltage gap maintained across an antenna. It seemed to me that an antenna might be like a wire where if there's a voltage at the top, the same voltage would be at the bottom, and hence no gradient and no current flow.

Several individuals explained to me that antenna is not a simple circuit element and goes beyond basic circuit analysis, and so there is no contradiction in it having different voltage at the top and bottom, which would lead to current flow.

One question that still bothers me:

Let's say that at one moment there's a positive voltage at the top of the antenna (10V relative to bottom, say), and current flows from top to bottom. But at the bottom where the antenna is actually connected, voltage is 0. That seems like the end of the journey, and it's unclear to me how the presence of a gradient in the antenna, also creates a voltage gradient in the circuit that drives the circuit elements?

On the other hand in the pic below it makes sense to me as the circuit is connected at 2 points in the antenna and there's a voltage differential between the 2 points that drives current to the radio circuit:

Old question:
In circuit sims and in theory, ground always maintains zero volts.

Thus if the point to which the ground is connected has more than 0V, some current will flow into the ground, while ground still maintains 0V despite incoming current.

But it looks like that in most real cases ground is merely a theoretical construct, and unless the circuit is earthed, the point labeled as "ground" can't actually maintain 0V, if the point to which the "ground" is connected in the circuit is above 0V, and current flows into the "ground".

Is there an element or some way to get "real" grounding, such that when the "ground" is connected to say a 1V point in a circuit, the "ground" will maintain 0V, despite current flowing from the 1V point to the "ground"? Otherwise the point labeled "ground" is just a loose wire that will quickly acquire the 1V of the point it is connected to, and not maintain zero volts.

My motivation is radio antennas where I'd like to have one end of the antenna connected to a permanent zero volts, so that when the top end of the antenna gets 1V, currently will flow from top to ground, while the ground maintains zero volts despite current flow.

on the left almost no current flows (just tiny bit to get other end of wire to match voltage of source), while on the right current flows steadily. If this was a real circuit, what can I do to make it behave like the one on the right, and not like one on left? I have antennas in mind, so that's why the simple solution of having 2 sided AC voltage source (i.e. like an AC 'battery') that maintains the voltage gap, like in the pic. below, won't help..

Thanks for your help!


texts: I'm TV technician, but I don’t know how to save or protect the boards in my workshop

texts:
I have main boards, power supplies, and so on as spare parts. But sometimes they spend several years in my workshop waiting for a customer. When I find the right customer, several times the boards were damaged, mostly because of corrosion.

How could I save the boards, obviously without damaging them (anticorrosion, silicon, and lacquer)?


texts: is there any reason to connect the center of winding to the ground of 3 phase rectifier? Or shouldn't I do that?


texts: Cutoff frequency of class A common-emitter amplifier

texts:
I'm trying to understand the operation of a class A common-emitter amplifier,
but I'm struggling to understand how the equivalent resistance for the cutoff frequency of C1 is determined. I also can't see how the equivalent circuit at the bottom left is correct.

Since the circuit splits in 3 after C1, it makes sense that there would be three parallel resistances. My first instinct would be to follow each of these to ground, and sum resistance along the way. Which would result in R1 | R2+RC+RE | RE, which is clearly wrong. I also thought to sum only the resistors before reaching the NPN, which left me with R1 | R2+RC.

So my question is, is there a rule for which resistors to include in the equivalent resistance of this circuit?


texts: Error on importing 3rd party model into LTSpice

texts:
I'm new to LTSpice but have the basics figured out (laying out a schematic, setting up simulation, running) and have done so with the basic but very well stocked library included. Of course my issue is I'm not using LT op amps.

I'm trying to import the model for the LM4562, but there are three options: PSPICE, and two TINA-TI which I'm not even sure what that is. The PSPICE package does not contain any .mod or .subckt files, rather it contains a .lib that has all the subcircuit information in it.

I have been trying for the last few hours to import the parameters and get it to work to no avail. All the tutorials are usually directed either at .mod files, or when I try to .INCLUDE the .LIB file, it throws errors that I don't fully understand.

I used the opamp2 symbol and modified it so that the pin names match up, or at least I believe I did (I could have done it incorrectly I suppose).

Below is a screenshot of the circuit I'm using to test it, and the error message I get:

Below is my Netlist:

D:\Projects\Electronics!TestCCt\opamp test.asc

V1 VCC 0 9

V2 0 VEE 9

V3 Vni 0 SINE(0 1 500)

R1 0 Vi 1K

R2 OP Vi 9.09K

XU1 Vi Vni VCC VEE OP LM4562

.INCLUDE D:\Library\Datasheets\Models\lm4562\LM4562.LIB

;op

.tran 0 25ms 0s 1ms

.backanno

.end

Errors are as follows. I'm not sure what nodes are floating:

**Circuit: * D:\Projects\Electronics!TestCCt\opamp test.asc

WARNING: Node U1:1:U11:VP1 is floating.
WARNING: Node U1:1:14 is floating.
WARNING: Node U1:1:U11:VP2 is floating.
WARNING: Node U1:1:U11:VP3 is floating.
WARNING: Node U1:1:U11:VP4 is floating.
WARNING: Node U1:1:U11:VZ1 is floating.
WARNING: Node U1:1:U11:VZ2 is floating.
WARNING: Node U1:1:U11:VZ3 is floating.
WARNING: Node U1:1:U11:VZ4 is floating.
WARNING: Node U1:1:9 is floating.

Direct Newton iteration failed to find .op point.  (Use ".option noopiter" to skip.)
Starting Gmin stepping
Gmin = 10
Gmin = 1.07374
vernier = 0.5
vernier = 0.25
vernier = 0.125
Gmin = 1.02385
vernier = 0.0625
vernier = 0.03125
vernier = 0.015625
Gmin = 1.01955
vernier = 0.0078125
vernier = 0.00390625
Gmin = 1.0126
vernier = 0.00520833
vernier = 0.00260417
vernier = 0.00130208
Gmin = 1.00833
vernier = 0.000651042
vernier = 0.000868055
Gmin = 1.00696
vernier = 0.00115741
vernier = 0.000578703
Gmin = 1.00536
vernier = 0.000771604
vernier = 0.000578703
vernier = 0.000771604
vernier = 0.000578703
Gmin = 1.00449
vernier = 0.000434027
vernier = 0.000578703
Gmin = 1.00351
vernier = 0.000434027
Gmin = 0
Gmin stepping failed

Starting source stepping with srcstepmethod=0
Singular matrix:  Check node u1:1:u11:vz3
   Iteration No. 1
Singular matrix:  Check node u1:1:9
   Iteration No. 2
Could not converge to DC with sources off!
Starting source stepping with srcstepmethod=1
Singular matrix:  Check nodes u1:1:14 and u1:1:9
   Iteration No. 1
Could not converge to DC with sources off!
Singular matrix:  Check node u1:1:9
   Iteration No. 1
Fatal Error: Singular matrix:  check node u1:1:9
   Iteration No. 1

This circuit has floating nodes.**

What am I doing wrong, and more importantly, how do I import this model correctly?


texts:
In the routing phase, how do you avoid track crossing error?

It seems I can't connect some pads without track crossing. Looks like I am missing some techniques.

Can anyone please help?


texts: Is it OK to attach an LED directly to a 5V Attiny?

texts:
From the datasheet, I though the AT90S1200 had current-limited pins and when running at 5V would sink the proper amount of current through a green LED attached to + (0 turns on the LED, 1 turns it off) without any external resistors. Unfortunately when I attached 8 of them the IC burned out after a few minutes. I also have a dodgy solderless breadboard and may have otherwise shorted out the part.

What did I misunderstand about that datasheet?


texts: Measuring AC voltage without a transformer using a microcontroller

texts:
As I have no practice with AC voltages, I'm asking if the following circuit is reliable for measuring AC voltages about 110Vca and 220Vca 50Hz/60Hz.

I have already made it with a small transformer. But now, I want a more compact way, because I'm planning to do a board for logic control (like PLC) which inputs detects 110/220 as TRUE. A second application is to measure de AC network level.

I have the foolowing questions about the circuit:

a) Is reliable? If not, a fuse could be a solution to stop the things when it goes wrong? (Consider that I plan to split the ~5M resistor in two, 2.4 or 2.7M).

b) In home the pins are phase, neutral and ground. Need I to connect the phase in C4 and the neutral as my circuit ground (or the ground pin is my ground too)? If yes, what to do in case of inverted connection?

c) What type of capacitor must be used?

Thanks in advance!


texts: Link between zero state response and the particular solution for an everlasting exponential input

texts:
In an LTI system, when the input is the characteristic function (i.e. an everlasting exponential function say \$e^{st}\$ ), the ZSR which is obtained by the convolution integral with \$h(t)\$ is \$H(s)e^{st}\$, where \$h(t)\$ is the impulse response of the system. Clearly it does not contain any characteristic mode terms. How do these terms get vanished?

Now if I go for the classical approach I get the particular solution for the input \$e^{st}\$ to be \$ce^{st}\$ . The constant c comes out to be \$H(s)\$ and hence I get \$H(s)e^{st}\$  as the particular solution which is same as ZSR. What does it mean, did I commit some error or are they actually equal? With the help of Laplace Transform  I can represent most of the signals in terms of everlasting exponential components. And hence as it follows from the above query, I should get ZSR and PI to be the same for most of the input signals. This can't be true. I'm sure I've gone wrong somewhere. Where have I gone wrong?


texts: Is there a way to impose current with an amplifier?

texts:
I am trying to design a circuit to drive an inductor.  I need to set an output current flowing through the inductor, and I want to set it no matter the resistance on the output.
I found some current feedback amplifiers like the LT1795, but this is not as simple as I thought.
I'm thinking about adding a shunt on the output and inject that in a difference amplifier before the current amplifier, but is that a good way to do so?


texts: USB Type-C Alternative with fewer signal wires

texts:
I love the new, sleek look of the USB Type-C connectors, and would like to use a connector with similar features in an upcoming project. The trouble is, I only need two signal lines, one additional line, GND and V+.
Observe the USB-C pinout:

I want a symetrical design that allows the user to plug in the plug in both directions, but I only need 5 signals, not 12. Besides, I am not using the USB protocol, so I couldn't use a USB-C connector (with any sanity) anyway.
Are there any symmetrical connectors out there that exist with fewer signal lines?


texts:
I have some christmas lights powered by 3 x 1.5v AA batteries, but the label shows they need 3v 0.06w.  Taking apart the very small circuit board I can see they are stepped down with a resistor.  Other questions here say quite simply - don't do this as you cannot guarantee the load etc.  which makes sense.

My problem has been that the lights will be at differing brightness when they all have fresh batteries, plus they only last a few days before I need to replace the batteries when I have another set of battery powered LED lights that will last for a month (at 6 hours per day).  I'm partly guessing the quality of the resistor is highly variable - but electronics is really not my area of expertise!

So the questions: does the use of a resistor have a detrimental effect on battery life?  Would replacing the pack with a simple switched 2 x AA battery pack improve things (so no need to try and drop voltage)?  Or how can I power more than one set of these lights from a transformer?


texts: How to remove the high pitched noise at the output of my audio amplifier circuit?

texts:
I'm trying to simulate an audio amplifier circuit in LTspice. I made this circuit based on the circuit I found here: https://circuits-diy.com/how-to-make-audio-amplifier-circuit-using-555-timer/ .
I'm able to discern the sound at the output, but there's an irritating high pitched sound along with the amplified sound signal. I tried adding a low pass filter also, at the output, but that ringing sound is still there. How do I remove this?
Also, why is this high pitched sound coming at the output?
Circuit diagram:

This is the audio file generated at the output: https://soundcloud.com/karun-mathews/test4
This is the sample input audio file I used:
https://www2.cs.uic.edu/~i101/SoundFiles/PinkPanther60.wav


texts:
I just bought a bluetooth module from Sparkfun http://www.sparkfun.com/products/10253RN-42

I have the power, ground, and tx,rx lines soldered onto and ready, I don't have a working TX/RX microcontroller solution at the moment, however I was wondering if I could connect the rx to the tx lines, so if I connect using BlueTerm https://market.android.com/details?id=es.pymasde.blueterm and try to type something to the bluetooth, I want it to just echo it back (as a test).

Would something like this work/make sense? Or will there be voltage/other issues? (I don't have a PC with bluetooth or serial support, so really my phone is the only option atm)

Thank you,
Tyson


texts:
This is a practice question from book: Engineering circuit analysis / William H. Hayt, Jr., Jack E. Kemmerly, Steven M. Durbin. — 8th ed. (pag. 91) .

Determine the nodal voltages in the circuit:

Ans: v1 = 3 V, v2 = −2.33 V, v3 = −1.91 V, v4 = 0.945 V.

And this is one of my attempts (The central node is the reference node):
When I solve the matrix (I do it through software so that's not the problem) the answers for voltages are not the right ones. And I don't know what I'm doing wrong (Maybe I'm not stating the equations correctly).


texts: How would you determine the Miller input and output capacitance for the amplifier in the figure?

texts: When I calculate the Miller input and output capacitance I get; Cin(Miller) as 6.38pF and Cout(Miller) as 5.66pF. However, these values are incorrect.


texts: Ultracapacitor, capacitance higher than rated?

texts:
Broadening my knowledge and experience about ultracapacitors I've made a test bench that was described in here.
I've used an IEC methodology to calculate the capacitance:
$$
C = (I_d*t_d) / (\Delta U)
$$
where delta U is difference of voltages equal to:
$$
\Delta U = 0.9 *U_r -0.7 * Ur
$$
where Ur is a rated voltage equal to 2,75 V
Other values that I've measured are:

td = 202 s
Id = 10 A

My calculation predicts C to be ~3600 F. Whereas rated capacitance of ultracapacitor is 3000 F. Are my calculations wrong or the calculated capacitance is a maximal capacitance available to achieve for this ultracap, but manufacturer limits it to 3000 F? Or assures only the 3000 F?


texts: 555 timed power at high to low edge in battery powered circuit

texts:
I have a lovely Atmel touch sensor whose output is high only as long as it's touched.  I want both off-on and on-off edges of its output to initiate two 3 sec pulses (and the time between edges is > 3 sec).  I route the output through a dual inverter (delay), which is XORed with the original to create a brief positive pulse at each edge. The brief pulses each trigger in succession the 555 which outputs the two 3 sec pulses.  If I just wire the inverter, XOR and 555 to the V supply (3.3V), then everything works great.

Complicating the situation is that I want to run off battery power and of course want to consume as little current as possible for long battery life.  As such, I want the touch sensor to sense continuously.  It is a low quiescent current sensor, so it doesn't load the battery too much.  But I want to energize the inverter, XOR and 555 only while the touch sensor is touched and for an additional 3 sec after it is no longer touched in order to do some start and stop functions elsewhere in the circuit (controlled by a PULSED_33V signal).

It's easy to power the components with the sensor touched/on in that I just send the sensor output to the base of an NPN tied high, which draws down a PMOS gate, which supplies 3.3V.  My challenge is finding a 'bootstrapping' strategy to keep power on for a moment just after the output goes off.  I sought to use two NPN's as an OR gate to the PMOS, the 555's pulse being fed to the base of the second NPN, and putting a nice fat 10uF capacitor between the 3.3V supply and the components' power inputs to energize them briefly until the hi-to-low 3 sec pulse arrived to take over keeping the PMOS on.  But it's not going as well as I'd hoped.

In the attached pic, notice the dual inverter (IC5) on the left.  I actually had to include an additional capacitor, since the interver's delay wasn't quite enough to provide a sufficiently delayed version to the XOR (IC2).  And I had to include an additional NPN inverter because the 555's (IC1's) TRiGger input expected a high to low transition to trigger it.  Continuing to the right is the RC for timer, an LED socket and resistor as a troubleshooting indicator, and finally the second NPN of the OR to the PMOS.  On the far right is the fat capacitor that I hoped would be sufficient to maintain power until the on-off edge percolated through to the 555.

Can anyone suggest a better strategy for keeping those components powered until the 555 can take over?  Or show me what I might tweak to get it to work?   Or just show me how my circuit is hopelessly flawed?  Thank you so much.

When the components are hard wired to 3.3V (removing R115 and shorting C9), touching the sensor causes the LED to light up for 3 sec and when the sensor is no longer touched, the LED lights up for 3 sec again.  But when trying to bootstrap with R115 and C9 present in-curcuit, the LED is bright for 3 sec, then is less bright until the sensor is not touched at which point the LED just goes off and stays off.


texts:
I've a pinball machine that keeps blowing the transistor for the flipper coil. The flipper coil has a diode across the lugs. This tested good but I replaced it with a new one anyway. Still blows transistor. I've buzzed out the lines from all three legs of the transistor and I am not finding any shorts and signals go to where they should. I know its not in the coil as I've connected the side that is not blowing to the one that is blowing and the flipper works fine like this. I feel the issue is somewhere on the board because I have blown the transistor with the the coil out of circuit.
The line going to the gate does have a filtering cap between the gate leg and the resistor coming from the signal. Could this cap be causing a ground short if it is failing and cause the transistor to short?
The transistor in question is Q15 and has been replaced with an IRL540N due to having a higher amp capabilities than the original. Cap in question is C248 and is 0.01uF. C256 is a blank pad. There is no cap on the board here.


texts: burden resistor and/or voltage divider in an energy-sensing CT setup

texts:
I want to (eventually) build myself a home power monitor using basic current transformers.  While reading on various circuit designs, I've stumbled upon what must be a very basic question.  If we look at the circuit diagram

here:

my question is:

What's the effective difference between the burden resistor and the voltage divider portions?

1) From my (clearly limited) understanding the burden resistor exists to put some meaningful load on the CT secondary - and in the process according to Ohm's law (?) it defines the ratio of the voltage across that resistor to the current in the secondary.  Is this correct?  -- a higher value resistor here will raise the voltage on the secondary, so you choose the resistance to get an appropriately-scaled voltage for your measuring tool... yes?

2) if I have that part right (and that's a big 'if'...) then why would I also need a separate voltage divider in the circuit?  Can you not just define your max voltage by the resistance of the burden?

3) bonus question: what is the purpose of C1 in this circuit - and why is there no value specified???


texts:
I am trying to find power in this circuit.

simulate this circuit – Schematic created using CircuitLab

I have calculated this multiple ways and I keep getting the same answer

R Parallel = 3.846-j0.769Ohm

R total = 3.846+j2.23Ohm

I total = 7/(3.846+j2.23) = 1.36 - j0.7898Amp

P Source Avg = (((7)(1.36-j0.7898))/2)cos(-30) = 4.76Watt

Using node to find Va:

((1/j3)+.25+(1/(-j20)))Va - (7/(j3)) = 0

Va = 4.63-j4.086 Volts

Va/4 = 1.157-j1.021Amps = (1.543<-41 degree)Amps

Power 4Ohm Avg = (((1.543)(1.543)(4))/2)cos(-41) = 3.594 Watt

or using loop

(4+j3)I1 - 4I2 +7 = 0

And

(4-j20)I2 - 4I1 = 0

4(I2 - I1) = 1.158 - j1.021

This is the moment I realised I have the correct answer using loop already written down

I am still unsure what is wrong with my node approach

((1.573*7)/2)cos(149) = -4.7182 Watt

Power average supplied by the source is: 4.76w

Power through the resistor is: 3.594w

Now I am reasonably confident in my answer but it does not make sense.  Because the average power through an inductor and a capacitor is 0 shouldn't the power from the source and the power absorbed by the resistor be the same amount?


texts: Is it possible to use AVR ISP programmer to program a PIC chip?

texts:
I want to try programming a PIC chip and just see, how much different it is compared to an AVR. I've got an AVRtinyISP and would like to know, if it would be possible to use that to program a PIC chip at all? What would limit me from doing that?

Both today's AVR and PIC chips have ICSP interfaces for program uploading and use apparently compatible pinouts for programming (PIC used to require a higher voltage supplied to program it, but newer chips don't require that anymore).

So my question is: is it even remotely possible to program a PIC chip with an AVR ISP programmer, such as AVRtinyISP or AVR ISP MkII?

Has anyone ever tried that?

If it's not possible or is too hard, then what are the limitations -- it is the protocols used, pinouts not matching exactly, voltages/current ratings, anything else? Is it possible to do that vice versa, i.e. using a PICKit clone to program an AVR chip? What would be the modifications needed to make anything of that possible at all?


texts: Why are some AC/DC adapters light while others are heavy?

texts:
I was browsing the thrift store and found a nice pair of JBL 2.0 computer speakers, but they lacked a power adapter. They call for a 12V 1A supply. I have a ton of "bricks" lying around, but no 12V ones to spare (if it's possible and economical to turn a 5V 3A brick into a 12V 1A+, please point me in the right direction). At the store I bought a cheap router that included the one on the left, but it's very light. I envisioned the necessary adapter to be very heavy, as any older computer speakers I've seen had a heavy brick, so I kept looking and found the one on the right sold individually. It's got to weigh 5x as much, but the specs look similar (I understand it's only 700mA and that means I can't draw as much power). If neither is a good fit I'd rather purchase a new one than chance it, but this got me thinking:

What's the difference between these two types of adapters?


texts: Using a via to strengthen surface mount connector on or near pad

texts:
I am trying to design a board that has a surface mount connector.  I was shown a picture of an example board that has vias on the pads of the connector.  I don't believe the via is for connecting to a layer necessarily. Meaning I was told that they were used for strengthening the mechanical structure near the connector so that it would be more difficult to yank off when pulling and pushing in the plug.

Has anyone ever heard of this? I believe I have heard of putting a plugged via right next to a mechanical pad so that the board is stronger there.  But I'm not sure what the implications are for putting a via on the pad?  I've been searching the web and I can't find much.  Maybe I just don't know the proper terminology for this application.

So is there a standard for adding strength to surface mount connectors? Is putting a via on the pad a good or bad practice, other than expense? Does putting a via directly next to the pad help?


texts: What is the purpose behind multiple addressing modes in a processor

texts:
Processors usually have multiple addressing modes. All processors do not have the same exact same list of addressing modes.

When exactly was idea of different addressing modes conceived?
Why do we need so many different addressing modes?
Why are the addressing modes transparents when programming in high level languages?


texts: SMPS typical drain current when MOSFET goes to saturation

texts:
Here an old smps circuit which is very similar to mine. But the gate driving voltage seems to be very high in my opinion.

Q1. If the gate threshold of the MOSFET is 2-4V , will the 12-15V pulse train from the UC3844 drive the MPSFET into saturation ( Id > 20A) ?

Q2. R4 and G6 don't seem to reduce the input gate voltage, then what are their functions?

Q3. What is the expected Id (in mA, I feel it shouldn't be more than 50omA else the 2W Rs will burse) ?

Q4. The primary impedance of the pulse transformer reads 1M ohms on DDM. Can't find any reference on internet so far. IS it way too high?

Thanks.


texts: No response from ST LSM6DS3 IMU breakout board using SPI

texts:
I'm hooking up an STM32F4 (discovery) to an LSM6DS3 IMU (or rather the breakout board from sparkfun) via SPI and I'm not getting a response. I have a logic analyzer hooked up to the IMU and I'm seeing this:

The only thing I could see being wrong with this picture is that the clock line begins too late after the start of my data. But I have no idea of how to fix that.

My freq is below the 10MHz limit and my Vddio is also below the max spec. I have two chips with the same set up so the bug is probably my own.

Here is my code. According to the datasheet 0xf is the who_am_I prompt.

#include "imu_control.h"
#include <spi.h>

void init_SPI1();
uint8_t SPI1_send(uint8_t data);

void imu_task(void* pvParameters){
  uint8_t rec = 0;
  init_SPI1();
  while(1){
    GPIOE->BSRRH |= GPIO_Pin_7; // set PE7 (CS) low
    SPI1_send(0x0f);  // transmit data
    rec = SPI1_send(0x00); // transmit dummy byte and receive data
    GPIOE->BSRRL |= GPIO_Pin_7; // set PE7 (CS) high
    printf("%d\n", rec);
    vTaskDelay(1000);

  }
}

void init_SPI1(){

  GPIO_InitTypeDef GPIO_InitStruct;
  SPI_InitTypeDef SPI_InitStruct;

  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_6 | GPIO_Pin_5;
  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOA, &GPIO_InitStruct);

  // connect SPI1 pins to SPI alternate function
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1);
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1);
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1);

  // enable clock for used IO pins
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, ENABLE);

  /* Configure the chip select pin
     in this case we will use PE7 */
  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7;
  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(GPIOE, &GPIO_InitStruct);

  GPIOE->BSRRL |= GPIO_Pin_7; // set PE7 high

  // enable peripheral clock
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);

  /* configure SPI1 in Mode 0
   * CPOL = 0 --> clock is low when idle
   * CPHA = 0 --> data is sampled at the first edge
   */
  SPI_InitStruct.SPI_Direction = SPI_Direction_2Lines_FullDuplex; // set to full duplex mode, seperate MOSI and MISO lines
  SPI_InitStruct.SPI_Mode = SPI_Mode_Master;     // transmit in master mode, NSS pin has to be always high
  SPI_InitStruct.SPI_DataSize = SPI_DataSize_8b; // one packet of data is 8 bits wide
  SPI_InitStruct.SPI_CPOL = SPI_CPOL_High;        // clock is high when idle
  SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge;      // data sampled at first edge
  SPI_InitStruct.SPI_NSS = SPI_NSS_Soft | SPI_NSSInternalSoft_Set; // set the NSS management to internal and pull internal NSS high
  SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_32; // SPI frequency is APB2 frequency / 4
  SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first
  SPI_Init(SPI1, &SPI_InitStruct);

  SPI_Cmd(SPI1, ENABLE); // enable SPI1
}

/* This funtion is used to transmit and receive data
 * with SPI1
 *          data --> data to be transmitted
 *          returns received value
 */
uint8_t SPI1_send(uint8_t data){

    SPI1->DR = data; // write data to be transmitted to the SPI data register
    while( !(SPI1->SR & SPI_I2S_FLAG_TXE) ); // wait until transmit complete
    while( !(SPI1->SR & SPI_I2S_FLAG_RXNE) ); // wait until receive complete
    while( SPI1->SR & SPI_I2S_FLAG_BSY ); // wait until SPI is not busy anymore
    return SPI1->DR; // return received data from SPI data register
}


texts: What is the behavior of an unprogrammed MicroController?

texts:
Problem:
I get Errors when trying to connect to the MicroController using the PDI interface. How does a MicroController behave when it hasn't been programmed? Is there a pin that will toggle to show me it's OK? Kind of a hardware "Hello World"?

I would like a way to confirm if the MicroController has failed or if I've done something else wrong.

Additional Information:

I've designed and had manufactured a custom board for an Atmel XMEGA MicroController, ATXMega64D3 to be exact. I'm using the ATXMega192D3 for prototyping, but these chips are identical except Flash/SRAM/EEPROM.

At this point the Power Supply is a verified and stable 3V3 Breadboard Power Supply to all power pins on the MicroController and the Power pins of the PDI connector. I have most of the decoupling Caps recommended in AVR1012: XMEGA A Schematic Checklist, section 2.1. I placed jumpers instead of the inductors & beads specified, and have not installed the electrolytic capacitors.

Total Parts installed = 6 qty 100nF decoupling Caps, 1 MicroController, 6-Pin header for PDI.

The MicroController is a 64-pin TQFP which I soldered on by hand under 7-14x Magnification. Then inspected for solder bridges.

I live in the Seattle area and it's been raining, I'm a native so I haven't turned the heater on. Odds of static damage are very low.

Programmer is an AVR Dragon, using the latest (non-beta) of Atmel Studio 6.0. Which reads the boards power level correctly but can't actually communicate with the MicroController.

My Current Theory:

I checked my design and the PDI Clock trace is 15mm long and the PDI Data trace is 25mm long, is this enough of a difference to cause Sync Issues? I would like a way to confirm this before going through the time and money of having a new board made.

Thank you for any help or ideas.

Update
Still not working, but I have found and fixed the following issues.

The MicroController was installed 180 degrees from what is required. The uC that I have has 2 circles in diagonal corners. When I first installed it I oriented the larger circle to line up with my Sikscreen. Only later when I read the logo did I realize that when the Logo is oriented correctly the Pin #1 identifier (smaller circle) is in the upper left.
Because I had started with the Voltage Regulator on the board, my power supply was set to 5V which is beyond the maximum voltage for this chip. So I have replaced the MicroController with an extra that I purchased at the same time.

At this time my theory is the AVR Dragon is my issue. The documentation states that the Dragon can connect to XMega with PDI but I have found multiple comments that seem to show about a 30% success rate, depending on the XMega model.

As an FYI with Power applied, the non-power pins read between 50mV and 300mV. Once again this is an un-programmed uC so there isn't any code running. This could be a leakage voltage or it could be the default configuration of the pins I'm not sure.

Solution

Using the AVR JTAG ICE 3 programmer it showed up, read the signature and fuses perfectly.


texts: Recommended Sensor? Distance - High Heat & Dusty

texts:
I'm after a sensor and I'm wondering what would be the best type for the following.

Requirements -
Accurately measure in the 5-10mm distance range, +/- 1mm.
Sense small undulations in a surface moving with a velocity of 500mm/min.
Most importantly - be reliable in a high heat, dusty environment.

It's going to be used to keep a cutting torch a set distance away from a plate, so this is the type of heat I'm talking about. Obviously if the sensor has the range it could be offset and calibrated, so it doesn't need to be sitting right next to the torch or anything.

I was thinking laser, but I've got concerns about the dusty environment. I wanted to confirm with more experienced opinions. Thanks.


texts: How to live with noise and ground loops in a system with Electronics, Power Electronics, Electrical Machines, Three-phase power and several boards?

texts:
I ask for help with a experimental assembly I am developing in the university, which is a small size power generation plant.

The system consists of a DC machine, a induction machine, several current and voltage sensors distributed in 4 boards, a AC-DC power converter to drive the DC machine, two power inverters configured as back-to-back and, of course, three DSPs, to control the whole system.

I sketched the diagram below trying to represent as close as possible the current physical assembly in the LAB. Turns out I am experiencing high levels of noise, voltage drops, reference divergences in several points, which is probably going to degrade the experiment.

My question is if you guys can help me with ideas to improve the system behavior regarding noise and references. Some considerations need to be made:

I did not yet put the machines and the converters to work in full, they are only connected and the converters are powered on. Even like this, the system shows the aforementioned problems. I think when the machines and converters are working, it won't be pretty.
All cables are NOT shielded, unfortunately. It is practically a standard of the devices that I own to use regular flat cables. I used, actually, CAT-6 twisted cables in some points, but not in the converters.
As you can see in the sketch, the several boards and power sources need to be connect in the same referential, which may lead to ground loops. Should I connect them all to EARTH GROUND?

Thank you in advance for the help and the ideas.


texts: What are the electronics parts of a CD player

texts: Can more experienced engineers give me their input on this. If I open a CD player, what electronic parts should I expect to find?


texts: DRO scales 4-pin connector identification

texts:
I've purchased some scales for use with a mini milling machine and the open source DRO-550 digital readout platform. They are essentially equivalent to permamenet mount digital vernier calipers so that the X/Y/Z position of the milling table can be tracked and displayed. The end product is shown below with the included LCD readout:

Many scales use a standard mini USB connector even though the protocol is more SPI-like, however these use a 4-pin connector that I'd like help identifying. In the first photo the top scale of the ruler is 1/64" so it appears pin spacing is either 1/32" or 0.8mm, which I've also confirmed by measurement to reduce parallax.

The following photo taken on a different angle shows there are two rows of pins although they are physically connected so it is a 4-pin connector. The overall outer dimensions of the protrusion that pushes into the socket is around 0.2" / 5.2mm wide by 0.12" / 3mm high, so a little smaller than a mini USB.

I'd prefer not to cut the cables and re-terminate so wondered if this is a standard connector type that anyone can identify?


texts: Can one end of a transformer be used as a choke?

texts: I want to build the "Death of Zen" audio amplifier and I found a video on YouTube of someone who built it and used a 10 mH choke for smoothing of the pulsating DC. I found an old transformer from an audio amp (line 6 low down studio 110) and I found a spot that is 10 mH on my LCR meter. Would this be suitable?


texts:
I am new to the TI MSP430G2553. I would like to send a PWM signal like in this picture:
(Image source: Adafruit - Understanding Infrared Signals)
However I can't do that, because I don't know how to stop (finish) the PWM signal.
Here is my PWM signal code:
void configTimer(void)  // this function sends infinite pwm signal when button is pressed
{
TA1CCR0 = 26-1;                          // Period
  TA1CCR1 = 13;                            // 50% dutycycle
  TA1CCTL1 |= OUTMOD_6;                    //  Reset/Set
  TA1CTL = TASSEL_1 + MC_1 + TACLR;
}

I tried:

TA1CTL1=0;
TA1CTL = MC_0;
set default value of TA1CCR1 = 0, when button pressed set TA1CCR1 = 13; and later __delay_cycles(any number);

However they didn't work.
Thanks in advance.

Edit: My last try
Edit2: Edit: I think can't use my timer interrupt my counter is always 0.
?
define TIMER0_A1_VECTOR    (8u * 2u)  /* 0xFFF0 Timer0)A CC1, TA0 */
define TIMER0_A0_VECTOR    (9u * 2u)  /* 0xFFF2 Timer0_A CC0 */
This is definiton of timer0 vector. How should i write it in my code?
#include <msp430.h>

void startTimer(void);

unsigned char counter=0;

void start2Timer(void);

int main(void)
{
WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer
BCSCTL1 = CALBC1_1MHZ; // Set range
DCOCTL = CALDCO_1MHZ;
CCTL0 = CCIE;

P2DIR |= BIT2;
P2SEL |= BIT2;// Select pwm  pin (transmitter)

P2OUT=0x00;

while(1){

if((P1IN & BIT4)!=BIT4) //button is pressed
  {
 startTimer();
 start2Timer();
  }

}

}

void startTimer(void) // pwm signal
{
TA1CCR0 = 26-1;                          // Period Register
  TA1CCR1 = 13;                            // TA1.1 25% dutycycle
  TA1CCTL1 |= OUTMOD_6;                    // TA1CCR1, Reset/Set
  TA1CTL = TASSEL_1 + MC_1 + TACLR;
}

void start2Timer(void) // trying to stop after 50 ms
{
CCR0 = 5000; // CCR0 5 ms
TACTL = TASSEL_2 + MC_2; //
}

#pragma vector=TIMER0_A0_VECTOR // Timer0_A0
__interrupt void Timer_A (void)
{
if(++counter==10){ // is counter 10 (5*10=ms)
 TA1CCR1 = 0;   ; // Stop pwm
counter = 0;
}
}


texts: Time delay: digital low pass filter VS analog low pass filter

texts:
I am new on digital filter, hopefully I can get some intuitive insights here. So, here is the question:

A low pass filter with 5Hz cut-off frequency is to be designed. The signals presented have maximum frequency of 1kHz. Therefore a 1MHz sampling rate will fully satisfy the Naquist Sampling theory for the digital filter part.

Analog Filter:

Say I want to implement a 5Hz analog low pass filter, I need to wait at least 0.2s, or even 10 times more time, to get one accurate data, because of the charging time of RC circuits.

Digital Filter:

Are things the same for digital filters?
Say I want to implement a 10 tap(data length) low pass filter with cut off frequency 5Hz.  The sampling rate is 1MHz. Can I get a valid data within 1/(1MHz/10) = 10us time? That seems not very reasonable to me....

Comments Needed:

In this application, two filters are to be designed.

In both filters, we only want to know the DC. The DC signal is buried in large noises. A cutoff frequency of 5Hz is chosen, since we want to have valid readings at 5Hz. And lower cutoff frequency means smaller noises, but also longer time needed to get an appropriate reading.

One filter has bandwidth of 6kHz(not 1MHz, which was just an example). And we are planning to over sample it with sampling rate of 36kHz. The other one filter has bandwidth of 60Hz, and we are planning to over sample it at 1kHz.

As can be observed from the filter description, we want lower noises, as low as possible. Therefore the digital filters are expected to have sharp edge at 5Hz. And all other parameters, such as "linear phase, small ripple.. and etc" are not important to us, since we only care about DC readings.

And, I am quite confused by the enormous types of digital filters.. How to choose them? Say, between FIR and IIR?


texts: Why would my mosfet driver output 1v when not triggered?

texts:
I've just finished building a DIY spotwelder using mosfets and driver chips.
You can find the build info here: https://github.com/KaeptnBalu/Arduino_Spot_Welder

(The creator is up to Version 3 but I'm building Version 1)

But I couldn't use some of the components he listed so I swapped out, mainly the mosfets from IRF3704 to IRF1405 - And the driver chips from MCP14E10 to MIC4424
(sorry didn't have enough rep points to post the links)

You can find the schematic here

The drivers are driven by an Arduino, everything is wired correctly as far as I've tested.

What I've found is the driver chips have an output of just under 1v when in the off state, this, of course, saturates the transistors.

I've found that if I put a 10k resistor from pin 5 & 7 from the mosfet controller ground to act as a pull-down resistor the circuit works correctly.

I'm just a little perplexed as to why there would be any output whatsoever, have I missed something in the MIC4424 data sheet that states that it needs a pull-down?

Any thoughts welcome.
Thanks.


texts: How does UBI determine a NAND flash block is bad?

texts:
I understand that if a block erase fails it can be marked as bad. If a page write fails immediately it can also be marked bad. I have a board that shows "read disturb" and/or "program disturb" errors after very few reads or writes, should UBI mark the block as bad?

Should erasing a block always reset the disturb level? If not, as in my case, what could be wrong? Could the charge pump within the flash chip be damaged? If so how could this have happened?

I have written a Linux driver to test the flash at the MTD level and after a "read disturb" has flipped bits in an erased page, subsequent reads of that page may be OK (no ECC errors). How can this happen? Is this expected?


texts: How do I implement authentication on an embedded device?

texts:
I have been reading a lot about encryption lately but most sources just care about making sure that the connection between two parties is secure. I want to know how I can be sure that the party I am talking to is actually the party I want to be talking to.

As far as I can see I can use something like AES-CCM to encrypt my messages and the keys used for this encryption can be shared using public-key algorithms. But what step do I need to take before that? Because is it not possible for another party to just simply initiate the public-key sharing with my device, which is then in turn used to share the symmetric key for AES-CCM?

I thought that the party that is trying to communicate with my device first needs to proof that he is authenticated to do so through some sort of password maybe. But that does mean I somehow have to save the password securely on my device. Is this how it is normally done? And if so how do I save this password securely?

I found this PDF file about a crypto-bootloader from Texas Instruments: http://www.ti.com/lit/wp/slay041/slay041.pdf. Here they simply save the keys in MPU-IPE which protect it from read/write access. But my device does not have that option.

Any insight into this topic would be highly appreciated. I am developing on Texas Instruments CC2652R1 in case anyone has experience with implementing this sort of thing on this device.


texts: Please help me in identifying surface mount component

texts:
So I've accidentally knocked down a computer system used to take kitchen measurements. I've caused a short in the power supply which caused two SMD components to burn in the motherboard. I've identified one SMD, but I'm trying to figure out what the other components is. I have identified several other SMD that match the one that burnt, but I can't figure out what it is. It has three pins and the one that burnt is close to a 12V power connection. The top surface of the SMD has the number 301 on the left side and two dots top center on the SMD. I've also noticed that under the damaged component it has the letter D followed by a number. I want to believe it is a Diode, but I'm not sure or what type. I've attached some pictures of the component that I'm trying to determine what it is so i can buy it and replace the burnt one in hopes to salvage this system.
This system is too old and the manufacturer no longer makes the board. I've asked for a schematic and component list and they can't provide it. Buying another one can cost between 15K to 30K. I'd like to try and see if I can replace the damaged component before I buy another one.
Any help will truly be appreciated. Thank you!


texts: Fixing the Collector Current for a BJT amplifier

texts:
I am doing a design of a BJT amplifier with the voltage divider biasing. I am trying to set up my Q points in the DC analysis.

Based on my notes from school and research online, I have set up the voltage divider using R_1 and R_2 so that the voltage at the base is V_be + V_Re and Ib is small. In this way I can ensure a fixed voltage across Re. Then I can select my value of Re so that Ie is equal to the Icq value I want. My next step is to then choose the value of Rc so that the voltage drop across Rc can give me maximum symmetrical swing.  Now lets say I build this circuit and need to vary Ic what resistor values do I need to change?  Now from my understanding, I did not set Ic using (beta x Ib) but rather by fixing Ie equal to Ic hence forcing Ic to be what I want it to be.  Therefore, I would adjust Re since the voltage across Re is fixed by the voltage divider to get my value of Ie which is approximately the same as Ic.  In this way I can change the value of Ic. Now I know one of the advantages of the voltage divider bias is so that the circuit is independent of changes in beta but not beta itself. Therefore, would it be correct to change Ic by changing Ib since Ic = (beta x Ib)?  This approach does not make much sense to me because Ic = (beta x Ib) was not taken into consideration in the initial design itself. I need some clarification as to whether the rule Ic = (beta x Ib) applies in this scenario.  I used the following as a guide.


texts:
I am trying to interface a dsPIC33EP chip with a RS232 device at baudrate=460800.
My code works OK but I think there must be a better way to do this. Here is the code:

void getData(unsigned char *Data) {
   int i=3;//EDIT: unsigned was removed
   UART1_Write(0x00);
   UART1_Write(0x86); //send two bytes of command to request data(4 bytes) back

   while (1) {

       if (U1STA.URXDA) {   // check if there is a byte available
         Data[i--]=U1RXREG; // shift a byte from UART1 internal receive buffer
       }

       if (i == -1) break;
   }
}

It polls new byte available bit constantly until it reads all four bytes. The baud rate is quiet fast so I think there is no problem making this function a blocking call.

Here is another version of it:

void getData(unsigned char *Data){
   UART1_Write(0x00);UART1_Write(0x86);//send two bytes of command to request data(4 bytes) back
   *(Data+3)=U1RXREG;
   *(Data+2)=U1RXREG;
   *(Data+1)=U1RXREG;
   *(Data)=U1RXREG;
}

Because I am expecting exactly four bytes to come in, and the FIFO buffer on the dsPic chip is four, I don't need to worry about overrun. The chip runs at 120MHZ.

According to testing, both of them work but my application is time sensitive and I want to avoid any possible errors. Which way is better? Or is there a better way to do this?


texts: Using two MOSFETs altenatively ON/OFF to simulate DC operation in the linear region?

texts:
In a previous question about using MOSFETs in parallel to increase current for DC operation in the linear region, it was pointed out that MOSFETs do not like to be used this way.

I thought of a way to avoid using the MOSFET in DC in the linear region (with the thermal problems) but still get DC at the output.

Could I use two sets of MOSFETs in parallel and activate one set for a time, then the other set, then the first set, and so on? I would use two Vin voltages with a Pi phase shift. Would that work? I'd calculate the switching frequency later.

The image shows two MOS but I could have 4 on each side to allow more amps.

I am very new to electronics, please tell me if it's stupid or if it may work. I do not have much requirement on the stability of the output. I just want to push some adjustable current to test that a fuse blows at the right current.


texts: IR transmitter Frequency for Universal Remote of TV and AC

texts:
I have searched thoroughly but still confused which IR transmitter will be best for making a universal remote of TV and AC.

Standard frequency is 38 kHz and others are 36, 38, 40, 42, 48 and 56 kHz.

Can I use 940 nm wavelength IR LED as a transmitter for my application, just for clarification?

Just like "Xiaomi Original Xiaomi Universal IR Remote Controller".

So please, suggest which will be best for my application.


texts: Calculating the Resistance using Mesh-Current Method

texts:
In the figure, if I = 80 mA, determine the resistance R.

simulate this circuit – Schematic created using CircuitLab

Answer is 600Ohm.

My Steps :

$$
I2=-0.08$$
$$20+R\left(I1-I2\right)+100I1=0\tag1$$
$$200I2+40+R\left(I2-I1\right)=0\tag2$$

So
$$20+R\left(I1+0.08\right)+100I1=0\tag1$$
$$24-R\left(I1+0.08\right)=0\tag2$$

Then
$$
R\left(I1+0.08\right)=24\tag{a}
$$

Now I sub (a) to (1) and get
$$
20+24+100I1=0\\
100I1=-44$$
$$I1=-0.44\tag{b}
$$

Sub (b) back to (a),
$$
R\left(-0.44+0.08\right)=24\\
R=-66.67 \Omega\\
$$

How to obtain the answer 600 Ohm?


texts:
I am learning circuit analysis in s-domain from my textbook "Engineering Circuit Analysis by William Hayt, 8th Ed". I am struggling with the mesh and nodal analysis.

In the book at page 583, there is a small practice question which I tried and my answer and the book solution don't really match. Can somebody help me show where I am getting things wrong?

The book solution to the exercise is:
$$
v_{x}(t)=[5+5.657(e^{-1.707t}-e^{-0.2929t})]u(t)
$$

My solution to the exercise is:
$$
v_{x}(t)=[5+7.07(e^{-1.707t}-e^{-0.293t})]u(t)
$$


texts: Extra (diode?) protection for H-bridge to prevent damage - how?

texts:
I am trying to use a IMS-1 H-Bridge with a 24V/20A psu and a motor 24V/20A.
I already burned one of these H-bridges in one direction and I assume that was caused by a back EMF.

Specs of the H-bridge are:

Rated voltage: 5V-24V
Maximum voltage: 5V-30V
When R1 position meets with a short circuit, VCC and B + shorted. VCC output voltage is the same with input voltage of the drive.
When R1 position open, VCC and B + disconnected. VCC input voltage 3-12V..
Current Rating: 20A
Peak Current: 59A
Switching frequency: 1K to 200kHz

So this thing already got some sort of protection but probably not enough. what circuit can I add between H-bridge and motor to get extra protection?
I want to make sure not more than 59A / 30V come back to it, better far below that.
I read a lot about circuits for this but all describe the circuit inside the H-bridge.

I am soldering for 30 years or more but my knowledge is like limited W/V=A :-/


texts: Maximum Voltage at CBOOT resistor and capacitor

texts:
I am using this Buck Converter to generate 3.3V output at 0.45A with Switching frequency of 2.1MHz.
Input voltage range is 6V - 16V. LM63625 2.5A Part is selected.
My questions :
Question 1:
In the datasheet, table 9.2 gives the value of the inductor and capacitors to be used. But there's this TI App Note for Buck Converter which helps to calculate the inductor value in section 3.
The Buck converter datasheet recommends to use 2.2uH inductor, whereas if I use the formula from the TI App Note, (considering 20% ripple current), I get an inductor value between 11uH to 13uH.
My question is why is there a difference between 10uH between the said value in the datasheet and the formula from the TI App Note? Which one should I follow?
Question 2:
Can someone tell me what would the maximum voltage across the Cboot capacitor 220nF? And how is it calculated?


texts:
Can someone explain to me a good way to mount a 5mm component LED? A little background on the project to help.

I'm working on a prop that will be carved out of styrofoam. I will be using LED's to illuminate recesses of the prop. The LED themselves will be mounted under a foam shelf or in a cavity so they are not visible to a casual view. There will of course be wires running though the interior of the prop to the LED's.

My question though is how to securely mount the LED's to the foam. I don't want them to wobble (the prop is handheld). A LED doesn't really have much surface area and I doubt applying glue directly to the LED is a good idea especially if I ever want to change it. Is there some sort of LED socket I can buy that the LED snaps into? If not how would you go about mounting an LED in a piece of foam?


texts: Calculating the resistance of curved resistive paste deposits

texts:
I want to make a pcb heater element using a graphite paste deposited by stencil onto a substrate. I want to insulate the cured paste deposit with a dielectric coating. The heater element will be DC.
The maker of the graphite paste gives the sheet resistance as <20 Ω/square/25μm.
I want to calculate the resistance of the paste deposit, but most of the paste deposit for the heater element will be in curved sections rather than straight lines. I can calculate the resistance for a straight line of graphite paste by calculating how many squares will fit into the line, but I would like to know how much the resistance will vary when the deposit is curved.
In this discussion
Does a coiled wire have a higher resistance than straight wire?
many people say the resistance will not vary significantly between a straight wire and a curved/coiled wire, so my first question is - would this hold true for a deposit of cured graphite paste as well as a wire?
I have been trying to think of the sheet resistance for one curved section - basically a half-donut shape with an inner diameter of 0.6mm and a deposit width of 0.2mm.

This page
https://www.thinfilm.com/resistors.html
says that

“The resistor “square” in the corner area(s) of a bent style resistor
(e.g. an “L” shape or serpentine design) should be counted as 0.56 the
value of the sheet resistance.”

Would this mean that the sheet resistance for a half-donut shape would be less than a straight line of the same length?
As I say, I can calculate the resistance for a straight line of graphite paste by calculating how many squares will fit into the line - can I still use this method of estimating resistance if the line is curved? Perhaps fitting squares into a straight line the same length and width as the curved line and then adjusting the value?
If anyone has any suggestions on estimating the resistance for these curved sections, I would appreciate any advice!


texts: I have heard that earlier PICs that are quite tiny are to be programmed using assembly and not C. Later PICs had hardware instructions to make them easy to be programmed via C language. However, I am not sure what this means.


texts: What ultimately determines the speed of electrical media

texts:
I have heard several myths about this.  Some have said "thicker wires mean faster speed" which I don't believe.  Others have said different voltages and others have said higher frequencies.

Take Coax for example.  Several years ago connections of 5mbit/sec were common, now today I am starting to see 100mbit/sec connections over the same physical medium of 5 years.  Same goes with twisted pair (cat5e vs cat6), one can now get 10Gbit/sec over copper.  DSL vs 56k.  Once again these are the same physical medium yet ADSL is sufficiently faster.

With that being said why are cable (coax) speeds always faster than DSL speeds (twisted pair)?

My question is essentially what determines the limits of speed of any particular physical medium


texts:
I'm building a custom model of the AT-ST from The Mandalorian:

I have the model almost done and I thought it would be really cool to add actual lighting to it.  The model is about 6" (16cm) tall, but I have a usable space of about 1.5" X 2" (3.8cm X 5.0cm).

My idea is to add 1-3 LED red Christmas light bulbs to the interior and one white LED bulb for the search light.  It should be attached to a on/off switch and powered by LR44 or similar sized batteries.

The problem is my Google powers are failing me.  I haven't been able to find the components needed for this project. So, my list of components (feel free to suggest a better solution):

Bulbs:  I mentioned LED Xmas light bulbs and I've found those easily. If anyone knows a better solution, please let me know.

On/Off Switch: The model is somewhat fragile, so I'd like the switch to be the slider-toggle style rather than a push button switch.  What is a good part for this?

Battery holder:  I mentioned LR44, but a different battery might be better.  From my understanding, the XMAS light bulbs use 2.5V, so I'd need 2-3 batteries to power my plan. What is this part called?

If this question is too simple for SE:EE, please let me know the proper exchange.


texts: HV Pulse Blocking with Common Mode Choke

texts:
I need to apply a reset current to a magnetic core on the same circuit as a ~25kV 30ns long pulse.  I know there are a number of ways to do this, but for simplicity sake I would like to protect my current supply with a common mode choke.
This is sort of what I'm thinking so far for this circuit, but the parameters of the choke are sort of elusive for a pulse rather than some harmonic noise.

Will a circuit like this be adequate to protect my voltage supply? Are there other factors that need to be considered?

Here is an example of the pulse that needs to be blocked (voltage axis not to scale):


texts: Mutual inductance with open circuit, what's the voltage of the open circuit?

texts:
I'm currently struggling to solve this problem (problem below), I need to find U2(t) but I don't know how. I've only solved problems of this kind with closed circuit.
Since the secondary loop is open I2 must be 0.

Our teacher labels voltage sources like current sources and my friend forgot to add the V. U1(t) is a voltage source.

While writing this I got a picture from a friend, is his method correct?


texts: Equivalent drawing of a parallel basic circuit

texts:
I have the following circuit in Everycircuit:

Ignoring the component values, when I try plotting this in a network graph, I get something like this:

Are these two circuits identical? I suppose the one 'confusing' component is the"X" between R2,R3 and R4,R5. (Perhaps a better way to make this would be to have those four 'wires' all meet at a common junction/wiring point.)

R1 = R2 = R3 = R4 = 1,000 ohms


texts:
I have a 5 V relay module connected to WeMos D1 board. The load is a small electric cooker.
The code turns on and off the relay every 5s for testing purposes.
digitalWrite(pin,HIGH);
delay(5000);
digitalWrite(pin,LOW);
delay(5000);
However, the green light and red light are always on.
there is no switching happening. An onboard led on the WeMos D1 board is blinking every 5s.
Relay specs:
https://www.ebay.com/itm/2PCS-1-Channel-DC-5V-Relay-Switch-Board-Module-for-Arduino-Raspberry-Pi-ARM-AVR/383693511233?_trksid=p2504926.m5232.l9681

int pin = 14;
void setup()
{
  pinMode(pin, OUTPUT);

}

void loop()
{
     digitalWrite(pin,HIGH);
     delay(5000);

     digitalWrite(pin,LOW);
     delay(5000);
}

Thank you!


texts:
I'm looking to make a high voltage supply for some geiger-mueller tubes (the ubiquitous sbm-20 russian surplus tubes that everyone uses).  these don't require much current at all, so creating high voltage shouldn't be too tricky.

I'm using a 12 volt source, and I'd really like there to be some way to fine tune the voltage (either by setting a duty cycle, or a current set resistor, or something similar).  I'd also like it to be as cheap as possible (meaning probably a preference for discrete components over ICs) while being reasonably sized (say, the size of a clamshell phone).

It seems that a reasonable way to approach this would be to create a two-stage converter: a boost converter to get me up to, say, 48VDC, followed by a series of voltage doublers until I get to 500 - 700 VDC.

This two-phase approach allows me to fine tune the voltage relatively easily, and I should be able to get away with using cheap discrete components.

My questions are:

Is this a reasonable approach? Are there simpler ways to create a similar, charge-pump style voltage supply? I'd really like to have the simplest circuit I can while maintaining some semblance of tunability and stability.
If so, how would I couple the boost converter to a voltage doubler?  Do I need a transformer? Can I just use the diode and capacitor as the first diode/capacitor pair in the ladder? Do I need a second FET to switch the boost converter's load capacitor into the voltage ladder?

Any schematics or similar would be extremely helpful.


texts: Is a VL3030 a suitable replacement for a ML2430

texts:
Hi i am attempting to replace a battery in my electronic compass and im supposed to use an ML2430 however this is proving to be hard to get hold of and expensive. Im concidering using a VL 3032/HF5N as an alternative.
I can make the difference in sizes work but am not quite sure if the electrical properties would fit. They both have a voltage V=3V and nominal capacity of 100mAh. However the ML2430 has a standard charge/discharge current of 0.5mA whereas the continuose standard load of the VL3032 is 0.2mA are these measures equivilant to each other if so will this difference cause issues? And should these components be interchangable?


texts: Does the CircuitLab simulation ignore OpAmp power rail current?

texts:
After I saw lots of simulations with CircuitLab here I subscribed today. And then I tried to simulate a simple circuit with an OpAmp which did not work as expected because I could not "measure" the current on the voltage rails of the OpAmp.

I simplified the schematic and here it is. When I simulate it the current on RL is between 0 to 15mA and the voltage between 0 and 3.5V. So far ok.

But if I measure the current on the OpAmp + and - rails the current it 0. I would have expected that the current on the positive rail is the same as the outgoing current.

What is wrong here? Does the CircuitLab simulation not work with this OpAmp (from their list) or does the current simulation on the OpAmp rails not work with any OpAmp or do I do something wrong here?

simulate this circuit – Schematic created using CircuitLab


texts: What does it mean that in a point Α of an electrical field the voltage is -7?

texts: The title. I am really confused. Does it mean that you need to spend 7J of energy to move Q=1C from there to somewhere where V=0, does the Q you move matter? Does it mean you need to spend 7J to move Q=1C from V=0 to A and the source of the field is negative?


texts: Do I need a gate resistor and/or a pull-down resistor for a TC4420 (or any gate driver) driving a MOSFET?

texts:
I've tried to search for this but I have [not] seen any combination of which resistors I need and which I don't need, so I'm not sure what to do.
I'm planning to drive an IRFZ44 MOSFET with a TC4420 gate driver. I'm doing that instead of driving it directly because I couldnt find a MOSFET that could provide the current I need at a given VDS, besides that, I'm learning something new.
I use 3.3 V as the input for the driver and 12 V as VDD for the driver. To my understanding the gate resistor reduces ripples and protects whatever is connected to the gate from to much current being drawn and the pulldown resistor lets the gate discharge fast when the mosfet turns off (is that correct so far?). But I'm not sure if these reasons still hold true for the TC4420. Does it need ripple protection? The datasheet says it can provide up to 6 A at 18 V VDD, so protecting it from overcurrent shouldn't be a problem. No idea about the ripples and pulling the gate low though. Could someone clarify that?
Example schmematic:


texts:
We are a hardware startup based out of Greece, looking for in-house PCB/FPC fabing solutions/equipment. LPKF's ProtoLaser U3/S look great but they cost $140K and $70K (if I'm not mistaken) respectively is prohibitive. We want to make our own in-house lab with a budget raging from €20 to €35K ($25~$45K).

Do you have any suggestions for: pick-and-place and (especially) laser etching machines fitting for such a budget? It would be very helpful if said machines originate from the EU.

PS: It was suggested to me that we could buy the parts and make our own, which can be the case for the PNP machine but the laser etching/drilling/depaneling machine will probably need to be bought because robustness, support and performance (SMD with 0.2mm pith) are crucial.

Thank you very much.

EDIT: The reason we want such equipment in-house is to considerably shorten the engineering-to-testing circle. In Greece, it takes weeks for us to get the PCBs/FPCs we ordered from an outside vendor, which is the problem we are trying to circumvent by making that as short us possible.


texts:
Here is a simple circuit that I simulated with LTSpice using UniversalOpamp2 component. C1 was initially added to remove DC voltage on inverting input. Sinus has a 0 offset, so C1 seems unneeded, but I kept it because I observed unexpected simulation results.

In this inverting configuration with a 1 gain, I expected an output of 5V - sine input. In simulation I get 2.5V - sine input, C1 capacitor removes 2.5V from dc offset on output.
Why?

EDIT :
From calculations, I we get this formula for :

Vout = 2.5*(1+R2/(R1 + 1/jC1w)) - Vin*R2/(R1 + 1/jC1w)

Said in others terms, offset and Vin have same gain

G = R2/(R1 + 1/jC1w),
only sign changes.

But offset on positive input, as a DC component has only a 1 gain as R2/(R1 + 1/jC1w) is 0 for a DC signal.

At 1kHz, Gain for sine should be

100k/sqrt(100k^2 + 1/(2*pifC1)^2) = 0.78.

That corresponds to our max voltage of 3.3V ~ 2.5+1*0.8

So to sum up... do not forget reactance when calculating opamp gain!


texts: Is there a circuit that amplifies current or voltage relative to signal frequency?

texts:
I am trying to create a circuit that outputs a higher voltage/current as the frequency of the signal input (such as an audio input) gets higher - such as to allow all frequencies to bypass a capacitor with a certain value. I have a design already, but I am not sure if it would work for this purpose, or at all.

simulate this circuit – Schematic created using CircuitLab


texts: Encounter: Hold time violation on clkgate

texts:
I'm trying to get rid of a clkgate timing violation. I have two of them and those are really big violations as you can see in this report:

+--------------------+---------+---------+---------+---------+---------+---------+
|     Hold mode      |   all   | reg2reg | in2reg  | reg2out | in2out  | clkgate |
+--------------------+---------+---------+---------+---------+---------+---------+
|           WNS (ns):|-157.134 |  0.001  |  0.751  |  0.013  |   N/A   |-157.134 |
|           TNS (ns):|-158.993 |  0.000  |  0.000  |  0.000  |   N/A   |-158.993 |
|    Violating Paths:|    2    |    0    |    0    |    0    |   N/A   |    2    |
|          All Paths:|  2951   |  2792   |   98    |   18    |   N/A   |   44    |
+--------------------+---------+---------+---------+---------+---------+---------+

Those violations are due to clock gating if I well understood the documentation but there is no more information about the resolution of this type of violation. The violated paths are related to a clock path between a JTAG and a memory.

I tried to use the -clkGateAware option in order to place the cells differently but it didn't help. I already tried to compile multiple time (10x in a row in the hold optimization bloc) but it didn't solve the issue...

What can be the cause of a violation as big as this one ? Is there a simple option that I can use to solve this issue ? Can someone suggest something clever to get rid of this type of clkgate ?

EDIT:
To be clearer: My project is composed of an ARM M0, two SRAM, an HW Accelerator and a SPI. There is also a JTAG slave in order to program the memory with the code for the M0.

All those peripherals are connected to the AHB bus and are working fine. The synthesis is OK without any violation path.
However, when I try to place and route the design, the clock gating occurs in order to reduce the power consumption. This also adds violating paths (two). So my question is more related to Encounter and the optimization commands: Is there something I can do in order to avoid this violated path ?


texts: What is the necessity of arc management in a circuit breaker?

texts: Why is an arc management necessary in a circuit breaker?


texts: How do transposition towers in transmission lines work?

texts:
There're such things as transposition towers in power distribution powerlines. The idea is that for example you have three conductors running in parallel at the same height and the leftmost of them is phase A and after transposition the middle one is phase A and the leftmost one in now phase C and phase B which originally was the middle conductor is now the rightmost one. Wikipedia says it's needed because

  The transposing is necessary as there is capacitance between conductors, as well as between conductors and ground. This is typically not symmetrical across phases. By transposing, the overall capacitance for the whole line is approximately balanced.

I don't get it. It's three wires in parallel before the transposition and three wires in parallel after the transposition and the distances between the wires are the same before and after the transposition (and the distance between the wires and the ground can hardly even be controlled because ground surface is uneven and changes over time).

How does transposing three parallel wires into three parallel wires help balance the line capacitance?

Edit: Buried in the comments of one answer is a link to a picture highlighting the arrangement of the phases on the transposition tower in the wikipedia article linked above. The picture deserves being shown here...


texts: What is the purpose of using a 1M Ohm resistor across crystal pins? Please refer to the image for clarity. The crystal serves as the clock source for an USB Hub device(LAN9512). There is nothing mentioned in the HUB datasheet about this, I suppose they have added it based on their experience, I have no clue about it.


texts: How to calculate rise time of linear regulator

texts:
Given a standard LDO with no soft start, that provides power to a bunch of decoupling capacitors, and a single chip.   How do you calculate the rise time of the output rail ahead of time?  Is it based on the time constant of the Rds of the internal FET into the decoupling capacitors and somehow minus the current draw of the part?

I don't really see the Rds spec'd in the datasheets I've looked at.


texts:
I'm a TA trying to convert a physical transformer circuit design that uses a transformer kit to an LT Spice simulation for some students who need practice but cannot attend my physical lab due to health concerns.
The physical lab uses a Function Generator set to 20 Vpp and 60 Hz with a 2 to 1 step down transformer. The idea is to use oscilloscope probes to measure voltages at points to determine their transformer kit's parameters. The students have to use Vb to determine the primary side current I1.

I tried implementing this in LT Spice following guides posted in the documentation for LT Spice and was getting the same voltage at point A as I was getting at point B, which I know shouldn't be the case due to the voltage drop across the DC resistance and windings of the primary. I'm getting 20 Volts for the measured voltages at points A and B. I'd really appreciate any advice on how to properly implement this in LT Spice.


texts: What are the tradeoffs between making my own current sense setup with a precision shunt resistor and ADC versus just buying something?  What are the most popular COTS current sensors for shunt current sensing?


texts: Do I Need a Series Resistor in Front of a Blinking LED?

texts:
I bought LEDs with a built-in chip which make them blink. The type of the LEDs are Kingbright L-56BSRD-B. The complete spec sheet is here.

After reading the spec sheet I do not know if this LED needs a series resistor.

The spec states:

With built-in blinking IC.
Operation voltage from 3.5V to 14V.

But then it has a row with the forward current:

IF Forward Current, Min:8mA, Typ:22mA, Min:VF=3.5V, Typ:VF=5V

Do I need a series resistor for this LED if I stay in the specified operating voltage range?


texts:
For an 3 phase AC motor, the full load current of a 3 phase motor is: $$I= \frac{P(KW)}{V*\sqrt3 *Pf}$$
when I was studying power factor correction, I came across some concepts like motor motor loaded at 25%, 50%, 75%, 100%.
What means a motor loaded at 25%, 50%,... and how the calculations for example of the current change in this case.


texts: How to create a static library for a UART sensor for STM32?

texts:
I am working on a project using the NUCLEOF103RB development board that interfaces with a fingerprint sensor over UART. I am using the TrueStudio IDE and would like to develop a "library" for the sensor that I would then want to import into my main project. I'm also using the HAL peripheral driver libraries to use the UART peripheral.

I have built static standalone libraries on a linux system using something similar to this: Creating a shared and static library with the gnu compiler (gcc). How does one go about doing something similar on TrueStudio/ARM gcc?

Many thanks!


texts:
Lets say we're in a car application, for the sake of argument.

We've got the 12v cigarette lighter adapter line (which is turned on when the car is on and off when the car is off), a 12v line straight to the car battery, and a separate 12v battery pack.

I want to use relays and a timer circuit to do the following (which I had a hard time putting in standard English), assume 12V-A = Cig Adapter, 12V-B = 12V line to car battery (always on/available), and BatPack = Separate 12v battery pack (always on/available):

    If (12V-A = on) then
    {
     BatPack = off;
     12V-B = on;
    }

    Elseif (12V-A = off) then
    {
     BatPack = on;
     wait(5s);
     12V-B = off;
     wait(55s);
     BatPack = off;
    }

If someone could point me in the right direction or provide circuitry, that would be awesome! I'm doing this not only to expand my understandings of analog circuitry, but to also be actually used in an application I have in mind.

If it's not too hard, the Elsif could be changed to:

Elseif (12V-A = off) then
{
 BatPack = on;
 if(12V-A = off) then {
  wait(5s);
  12V-B = off;
  wait(55s);
  BatPack = off;
 }
}


texts: Can this used with Arduino to send SMS to phone?

texts:
I want to know the possibility of using this TC35 board to send SMS to my phone?

If there is possibility, what about codes? Does anyone have relative codes for it?


texts: IC / logo identification: 5.8 GHz radar MMIC marked "5810"

texts: Can anyone identify the pictured IC or the manufacturer logo on it? It's a 5.8 GHz radar MMIC with 1 Tx, 1 Rx, PLL, power amplifier, mixer, and low noise amplifier, presumably from an Asian semiconductor company. It's in a 3x3 mm QFN package with 20 pins.


texts: Why the power supplies limit the amperage?

texts:
I'm just learning electronics, and I can't understand something:
If the amperes don't matter in terms of burning the circuit, only voltage, why do phone charges for example have a low current capability?
I understood from the various explanations I've read, I've read that it's okay to use a power supply with higher ampere rating, but not with different voltage. If the ampere rating is the maximum that device can supply, it only consumes what it needs, right?


texts: How to calculate the area that a chip occupies in a design system

texts: Can someone help me to find how I can calculate the area that a chip occupies in the design system of the ADS(Advanced design system) software? It is possible in this design program?


texts: Driver selection for driving multiple MOSFETs

texts:
I am currently working on one of the BLDC drive applications.Due to higher current requirements it is planned to use multiple MOSFETs in parallel to distribute the current among themselves.

Here I wanted to know whether the gate-drive current from the driver  I am using is sufficient or not. Could somebody give hints or procedure to make sure the driver you have chosen is right one? (You may consider example values as
Vdriver(max)=12V,
Vdriver(min)=0V,
I_driver(max)=2A,
MOSFET gate charge=150nC,
No. of MOSFETs in parallel=3,
Switching frequency = 16kHz.

I hope these are the basic parameters to do the analysis. Assume if you need anything else.


texts: What sort of applications does the normal distribution have in electrical engineering?

texts: Need to know just two. Sorry for posting this here (arduino). Seems there isn't a soft-questions tag. Thank you for your help.


texts: Why do AM radio stations have secondary frequencies?

texts:
First thing I'm sorry if this question sounds too much beginner-ish. I don't major in electrical engineering so I may lack the basic knowledge.
I have been noticing that, while tuning my AM radio, nearly all stations have a "secondary frequency" that transmits the same audio as the advertised frequency. However, the quality of the audio is a little lower than the advertised frequency. For instance, the channel's advertised frequency is 675 kHz and I found the secondary frequency at 630 kHz. Another example is that main frequency at 549 kHz and secondary frequency at 729 kHz.
The pairs of main-secondary frequency do not seem to follow any patterns or rules. So my question is:

Is this on purpose (as a backup frequency or something else)?
If it's not on purpose, why does this happen?

More information: My radio is a basic consumer radio (Sony) with FM and AM (AM radio tuner is ranged from 531 kHz to 1602 kHz, with 9 kHz step between frequencies).


texts:
I'm going to be doing a final year project revolving around music production and DACs are pretty important. Not going to go into detail (unless this question requires it) what the project is but I will need to know the specifications of the DAC that the HTC 10 phone is using.

This isn't the one that Snapdragon put on the chip, I'm looking for the specs of their stand-alone DAC. They claim its "studio quality" so I would also like to know if this is true, when compared to those expensive external DACs most audiophiles or music producers purchase.

Thanks in advance.


texts: Impedance and resonance frequency of a bias tee

texts:
I am a beginner trying to learn about combining impedances and solving for the resonance frequency. I am solving a circuit:

simulate this circuit – Schematic created using CircuitLab

and I have managed to redraw in a way that is more familiar to me.

simulate this circuit

Now I am calculating the total impedance, first for Z and C3 in parallel, and their equivalent impedance in series with L1: $$Z_{eq} = \frac{1}{ \frac{1}{Z} + j \omega C_3} + j \omega L_1$$
and then finally all of them in parallel with C2:
$$Z_{total} = \frac{1}{\frac{1}{Z_{eq}}+j \omega C_2}$$

than I was planning to use the formula for the reflection coefficient:

$$\Gamma =  \frac{|Z_{total}-50|}{|Z_{total} + 50|} $$ assuming 50 Ohm matching and extract the resonance frequency where it becomes 0.

I do not know how to include the remaining part of the circuit in my calculation of impedance. As far as I understand, the remaining part serves as a bias tee (it is not clear why is there a resistor R1 instead of an inductor though). Does it contribute to the resonance frequency?


texts: Capacitor Numbers, What do these markings mean?

texts:
I have this capacitors and I tried learning how to read them but I am still unsure. I believe these are 330uf 16v capacitors but I dont know what the 282 means. Or if I am even correct.

What do these markings mean?


texts: Why only shared resistances are taken into consideration while computing Elmore delay?

texts: While we compute the delay , using Elmore delay model we take into consideration the shared resistance and capacitance. I would like to know why are we only concerned with shared resistance not the other resistances.


texts: Reflection Coefficient with Electric Field and Voltage

texts:
In different situations the input reflection coefficient (of a waveguide, of a transmission line etc) is defined differently.

Wikipedia says:

  The reflection coefficient may also be established using other field or circuit pairs of quantities whose product defines power resolvable into a forward and reverse wave. For instance, with electromagnetic plane waves, one uses the ratio of the electric fields of the reflected to that of the forward wave (or magnetic fields, again with a minus sign).

So, let's consider for instance a coaxial cable. We may define its input reflection coefficient as the ratio between reverse and the direct travelling voltage waves (V-(z)/V+(z)), but also as the ratio between the reverse and the direct travelling electric fields (E-(z)/E-(z)).

Are these two reflection coefficients the same?


texts:
I have a faulty PMOS that I have to replace, but the part seems to be out of stock. STL6P3LLH6
I have found a very similar device spec-wise, but there is some difference between the two. The original part's datasheet has positive Vds, Current throughout the datasheet, while the replacement has the normal negative values on the datasheet.
On the first page of the original part's datasheet, there is a comment like the picture below, which I think it means that the original datasheet's Vds and current is negative in value.
Is it conventional in PMOS datasheet to do this? It's my first time seeing a datasheet like this.

Original part

Replacement part


texts: I have a question about node analysis method. The part I could not solve is the Node c's equation. In equations, C is represented by 3.Here is my question what is G5(i=GV) in the circuit. The empty wire has current but there is no voltage when I simulated circuit in Proteus. And the part makes me confused is if we have got current should we write that current in the 3rd equation. And if we write that current what is the 1/R for the empty wire. I just try to solve those equations in Matlab but the results were not the same as Proteus. Please help me, I stuck on this part in question. To conclusion, my question is should I add current in the empty wire in equations and if I add what is the G5.