texts: Why does the UART not report an error for a data byte with wrong parity?

texts:
I am trying to learn about UART Serial communication of the MSP430FR6989 from Texas Instruments.

Datasheet

User's Guide

I doing a program where my UART will send a character through the TX pin of my microcontroller and receives it through the RX pin.

If we take a look at the Block Diagram of the MSP430's UART module (eUSCI - UART Mode), it will look like this

(Page 766/1021 of UG)

A 32.768 kHz Auxiliary Clock Source will be the source of the BRCLK (Baud Rate Clock), I will enable the Parity bit (UCPEN = 1), and set it to count even 1s (UCPAR = 1). I will put a value of odd 1s into the Transmission buffer (UCA0TXBUF = 1001 0111). Now I expect the Parity Error Flag to be set (UCPE 0-> 1).

(Page 784/1021 of UG)

(Page 787/1021 of UG)

This is a snippet of the code

int main(void)
{
    //code

    set_Clock_Signals (); //sets f(ACLK) = 32.768 kHz
    set_UART_Pins (); //P4.2 and P4.3 are UART RX and TX
    set_UART_Baud_Rate ();

    UCA0CTLW0 = UCSWRST; //put UART in reset mode

    UCA0CTLW0 = UCA0CTLW0 | UCPEN | UCPAR | UCSSEL0;
    //enables parity, parity is even, selects ACLK CS

    UCA0CTLW0 = UCA0CTLW0 & (~UCSWRST);
    //we can send and recieve data now

    UCA0TXBUF = 0x57; //Line A
    //0101 0111

    while(1);

    return 0;
}

I build program, and started debugging it, what I expected was when the debugger steps into Line A, and steps out of it, I will see UCPE bit to be set, but instead I didn't get an error.

Steps into the next line, no error, and it works fine.


texts: Why is VGA connector has only one pin for red color data but is composed of 8 bits?

texts: VGA connectors have 15 pins, three of these are used for color data of red, blue and green. Based on this project, each color has a width of 8 bits. However if under the scheme of 8-bit color, each color will have 8 bits of data. (Upon further inspection, 8-bit color means 3 bits red, 3 bits green and 2 bits blue) How can you have multiple bits of data in one pin?


texts: Thevenin equivalent for a transistor circuit

texts: I'm having trouble with this circuit and was wondering if someone could help me. So far I know that the 20V source can be basically ignored since it is a NPN transistor here. The second circuit here is where I've gotten so far, but I'm not sure of all the values. I'm not sure what the value of the lower resistor should be. Is it still just 1k or is there something I'm missing?


texts: Ground plane: is there a tool to identify choke points of a fragmented copper polygon in Eagle?

texts:
As they say a picture says a thousand words. Consider this extreme example:

You have this copper polygon (a ground plane), but due to other signals routed on the same layer, the polygon comes to a choke point (the "strait" between Pad2&3).

I assume this makes it a suboptimal ground plane (comment if I'm wrong).

Is there a tool in Eagle to identify such problematic choke points? (I'm using Eagle 5.11).

For the example it is trivial to see it visually, but the actual board I'm worrying about is much more complicated and it's hard to identify anything by just looking at it. The tools tells me it is bad though, because I had to stitch the GND planes (I have one on both top and bottom, it is a 2-layer PCB) with dozens of vias to avoid empty areas with no copper.
In terms of the frequencies involved, the PCB is a mostly digital device that has a few micros, some at 16 MHz, one at 200 MHz.

One way to do it that comes to mind is to temporarily increase the isolation parameter on the ground polygons, and recompute the fill - it would separate on the choke points and probably airwires would emerge, but I don't think this is a particularly elegant way.


texts: Convert counts CCD output to irradiance units

texts:
I'm performing some tests with a spectrometer (a model similar to this one but more recent) equipped with a CCD. I can only output to counts, not W/(m^2*nm) (ie: irradiance units) which is what actually I need.

Is there a way to convert from a CCD counts units to irradiance units? The manual for the device says nothing about this.


texts:
Why placing connectors on the same edge of the PCB is recommended as an EMC design guideline?

As mentioned in https://learnemc.com/pcb-layout

All connectors should be located on one edge or on one corner of a board.
Connectors represent the most efficient antenna parts in most designs. Locating them on the same edge of the board makes it much easier to control the common-mode voltage that may drive one connector relative to another.


texts: Smoking Transistor in Low-Side Switch. What Am I Doing Wrong?

texts:
I have some of these (RGB LEDs with drivers). They connect to 12V, and they draw a max of 1.8A total (full white):

I wanted to add a low-side switch to turn the load on/off via a PIC I/O pin output. After getting some advice in this thread, I created the circuit below:

The values above are what I expected the switch to behave like. According to the TIP31C transistor datasheet, Ic=1.8A gives a Vbe(sat) of 1.0V, and a Vce(sat) of 280mV, which apparently shouldn't get very hot:

Instead, I'm seeing this:

After a few seconds of being on, the transistor starts smoking and is way too hot to touch.

Can somebody please explain why there is a difference between what I expect to see and what I am seeing?

Note: my electronics knowledge is pretty basic, so please assume I don't know much, I won't be offended :). If I've left off any necessary information, please comment. Thanks!


texts: The loop ones. I've never seen them before.


texts: PCIe card Dimension Half-Length 106.68 × 175.26 Specification Devaiation

texts:
As per the Wikipedia and other Sites, the dimension of the Half-Length  PCIe card is 106.68 × 175.26, https://en.wikipedia.org/wiki/PCI_Express
But as per the specification,
Kindly clarify. How the length of 175.26 has arrived for Half-Length PCIe card


texts: How do manufacturers determine LED characteristics?

texts: I have several hundred clear LED's of mixed colour and would like to sort them and determine their characteristics so I can use them. As far as my research tells me, there is no way to determine the forward current of an LED directly, and in order to determine forward voltage you need to know forward current. My question is, how do LED manufacturers determine these values, and is there any way I can do the same?


texts: Attaching a resistor to a oscilliscope probe

texts: I'm doing some ultra low power electronics, and I need a probe with an impedance higher than 10Mohm. Is it alright to just attach a 90Mohm resistor to the end of my 10x probe to turn it into a 100x probe? The signals are all under 1Mhz. Are there any problems that could arise?


texts: How to flash binary code to the NUCLEO-F207ZG device?

texts:
When I want to upload a binary file executable.bin to the STM32F407G device, I connect it to the PC using the mini-USB cable and execute the command
sudo st-flash write executable.bin 0x08000000

Now I want to upload the binary file in a similar way to the NUCLEO-F207ZG device:

but this time sudo st-flash write executable.bin 0x08000000 throws an error
st-flash 1.6.1
2020-07-14T18:42:02 WARN common.c: unknown chip id! 0x374b
Failed to connect to target

What am I doing wrong?
I also installed pyocd command to flash the code. pyocd list returns the following information about the device:
Probe          Unique ID
STM32 STLink   066DFF485550755187123543

On the physical device, I see a number F207ZG and one target in
the pyocd list --target is stm32f207zg, thus I try to
flash the code with the following command:
pyocd flash --target stm32f207zg -0connect_mode=under-reset --base-address 0x08000000 executable.bin

but receive an error:
pyocd.core.exceptions.ProbeError: STLink error (9): Get IDCODE error

What am I doing wrong in this case?


texts: How does an AM-modulated signal sound like in a speaker?

texts:
Let us compare two signals: one is a normal sinusoidal signal with single frequency 5khz with 1V amplitude (2V peak-to-peak). The other signal has a carrier frequency of 5khz and 2V peak-to-peak, but is an AM modulation signal with modulation waveform frequency (or message frequency) of 900hz, with some modulation index.

Now these two signals generated by function generators are each connected to speaker, generating sounds.

My question is, would both signals sound similar in pitch (frequency) to our ears? Or would modulated signal's pitch sound more like 900hz than 5khz?


texts: How to know how many LEDs can be used at a given voltage

texts:
I am newbie to electronics. Basically I developed a mini circuit just to understand concept of electronic circuit. What I did was I developed a circuit with 3Volt AA battery and 1 LED. The LED lighted up. When I increased the number of LEDs to two, the second LEDs didn't light up.

So, I increase the number of battery so that it became 6Volt. The two LEDs light up fine. Then I added the third one, but only two light up and the third one didn't. Also I noticed that the brightness of the light is decreased when I add the third one.

For your information, I connected the LED in series. My question is, how can I determine the number of LEDs can be used for specific volt? I understand that LED is not a resistor, so why the volt dropped from LED to LED in series and how to determine this?

I did know the V=IR thingy. Thanks.


texts: Inductor Machines: why is constant flux achieved before reaching nominal speed?

texts:
It is observed that an induction machine increases its voltage linearly before reaching its nominal speed. This is achieved due to the emf generated by the rotor movement.

However, I find it difficult to understand why the flux is kept constant while the induction motor increases its speed. See following image:

Could anyone shed some light in this matter?

Thanks in advance,


texts:
I'm personally developing an analog circuit for a photo sensor using very cheap op-amp. My biggest motivation for my circuit is to design it cheaply as much as possible.
My main op-amp is a TL071. NE5534 is also used because good ability of driving current is necessary in my Peak-Hold circuit.
LTSpice (picture_1) and a circuit I made (picture_2) have relatively similar response. However, it seems that I have to make signal pulse narrow more so that I perform photo counting. Now, rising tales ~1 μs, and I would like to make it 500 ns. To do it, I probably have to use a bit more better op-amps.
Here, many engineers are joining. So, could you suggest anything useful: Op-amps for making the pulse narrow more, ideas and comments to brush up my circuit.
Best regards!


texts:
I have seen several blog posts that discuss the concept of a nonlinear capacitor (or inductor) here, here, and here. Thanks to a concerned citizen for the references.
I'm still struggling with the execution of this for my capacitor. Below is a screenshot of the capacitor I care about in a schematic. I ultimately want this variable-gap capacitor to have a time-dependent capacitance, given by C = eps*A/(g0+g(t)). You can ignore the "disp sin(wt)," that was simply messing around.

I have made simple circuits with a behavioral voltage source and I have changed the capacitance to be expressed in terms of charge, i.e., Q = x*C (where C was just some constant, for testing, as shown below). In that equation, x is the voltage drop across the capacitor, per the LTSpice manual. I looked at the current through it and that is simply the derivative of the charge, so I end up with a cosine wave due to the sine wave voltage input. This makes sense.

My notion as of now is to try and get the current in this second image to be equal to the variable-gap capacitance (by using some behavioral voltage source that is a function of g(t)). But even if this were to work (which it may not, please let me know otherwise), I'm not sure how to link this to the capacitor in my original schematic. I can't figure out how to set the capacitance value equal to a current (i.e., how do I link the capacitance in the first figure to the capacitance in the second figure?). I have tried net labels.
I hope my explanation was clear and I appreciate any time/effort provided in explaining things.
Sincerly, a mechanical engineer with little Spice experience


texts: smd resistor and regular through hole resistor

texts:
My question is fairly simple. I am building an SMD LED board and i am limited in space. So originally i was planning on going with through hole resistors, but have it being i'm very limited on space i'm looking at the option of going the smd resistor route.

Essentially what i need is a 68 ohm 1/4 w through resistor but i want to use an smd resistor. When i type in 68 ohm 1/4 smd in ebay it showed me the 1206 SMD type (here's the link) http://www.ebay.com/itm/50-Value-1206-SMD-Resistor-Kit-0R-10MR-5-5000pcs-/330655035675?pt=LH_DefaultDomain_0&hash=item4cfc93711b
*i then got excited and realized that a 68 ohm SMD might not be the same as a 68 ohm 1/4w through hole resistor, so what would be the equivalent to the through hole resistor in a smd resistor type

It has all the ones i require but i want to be sure i'm buying the correct ones.
Again i apologize for the such noob question but i want to be sure i buy the correct one before i burn out my LED.

and on a side note. i use an LED calculator (link) http://led.linear1.org/led.wiz

Do you guys think it gives the correct values for and SMD LED as well. Any suggestions i will happily take. I like learning the correct way of all things i've been doing bad.

Thank you in advance


texts: What caused these crystals to grow on overheated PCB?

texts:
Source
This is a picture of a screw terminal on a 3d printer mainboard that overheated or caught fire, likely due to a loose connection or overcurrent. One thing that caught my eye is the crystal formation in the heat affected area. What is that? Does it give insight into what caused the damage?


texts: How do I solve this Circuit with Mesh Analysis method? Help Please. Specificly with mesh analysis please, with nodal analysis its easy.


texts: Does an ARM (LPC21xx) Programmer pulls P0.14/BSL to ground?

texts:
Most of ARM programmers come with BSL,RESET,TXD, RXD, GND and VCC pins which we need to connect with respective pins of ARM.

For ISP, We require need to ground P0.14/BSL after Reset.

As these programmers have Both BSL and RESET pins, Does programmer itself Resets controller and pulls BSL to ground OR do I need to first pull BSL to ground, Reset controller and then start programming using softwares like FlashMagic?

Also,
Does ARM remains in Bootloader if I pull P0.14/BSL to ground after power up till next reset or does it have any sort of time out that it will jump to application code after that.

Or as Wouter van Ooijen rephrased it,
whether the bootloader will spontaneously jump to the application after a certain timeout?

I am working with LPC2138.


texts: Low-frequency high.pass filter drifts with temperature

texts:
for a phase sensitive measurement, I would like to have the DC offset of a signal cancelled. The AC-signal will be amplified and then the phase of it is measured in reference to another AC-signal.
My attempt was using a Sallen-Key-Highpass filter with a cutoff frequency of 4 Hz which first worked fine. I recognised, that the phase of the filtered signal shifts with temperature which I want to avoid. I am using C0G ceramic capacitors (220 nF) and resistors with a relatively high resistance of 180 kOhms.
I read about the concept of the DC servo filter which I could also try to implement, but is it promising for what I want to achieve?


texts:
I have designed a peak detector to capture the peaks of high speed pulses. This is the circuit:

This is the waveform obtained on simulation:

Waveform when input peak is about 2.5 V:

Orange is PR3, output of peak detector. Blue is PR4, output of Op- Amp U1. Red is PR1, input pulse.
I use Comp_1 to discharge the cap C2, after the pulse has ended. This is done to capture peak of all the pulses (regardless of the value).

Could someone suggest how I can fix this issue?


texts: What am i missing for this to work? (Zener Diode)

texts:
Since the zener breakdown voltage is set to 5v, i actually thought that the voltage would be 0, since it goes directly to ground, I just wanted to try a "simple overvoltage protection". How is it that the voltage is 5v instead of 0? Without the diode, the voltage is around 22 volt or so.

Can anyone explain why this is and maybe give a few examples on how to fix it?
(This is my first time working with Zener Diodes)

Thanks!


texts: Decoupling Capacitor - Multiple Vss pins

texts:
I'm about to start using a chip that has one positive and two ground connections - I've only used chips with one positive and one ground before.

How should I attach the decoupling capacitor(s?) to this?

Should I just have one capacitor across pin 20 and 19?


texts: Customzing the Arduino Mini Pro 3.3V/8Mhz. What component can I remove from the original circuit?

texts:
I am trying to custom design my own microcontroller circuit and want to eventually embed it into my system. I decided to use an Arduino Mini Pro 3.3V/8Mhz provided from Sparkfun and the links for the schematic of the board and the design files are shown below.

https://cdn.sparkfun.com/datasheets/Dev/Arduino/Boards/Arduino-Pro-Mini-v14.pdf
https://cdn.sparkfun.com/datasheets/Dev/Arduino/Boards/Arduino-Pro-Mini-v14.zip

My question is, what component can I remove from this original circuit? For example, something like "LED1" and "R11" doesn't seem like to play any critical role in its circuitry.

By the way, I removed the "R6" and "D3" to test if I can compile and upload the code using Arduino IDE, but did not work after removing those two components.

Can anybody tell me why? I tried to look at the datasheet, but no luck so far.

Thank you in advance for your advice!


texts: How do I really calculate these resistors?

texts:
I am learning about it.

I would like to focus on this circuit

I am trying to calculate R10 and R11.

I want Ic = 10 mA. Transistor is 2N2222A.

This is an amplifier. If I understood how amplifiers work, I want Vc to be in the middle of the rail, so the amplifier will have maximum output swing. The circuit is powered by a 9V battery, so the middle of the rail = Vc = 4.5V.

So, I have calculated Rc like:

\$ R_C  = \frac{V_{CC} - V_{CE}}{I_C} \$

\$ R_C  = \frac{9 - 4,5}{10 \times 10^{-3}} \$

\$ R_C = 450 \$ ohms.

I have calculated Ib like this:

\$ I_C = \beta I_B \$

\$ \beta = 225 \$ for 10 mA

so,

\$  I_{B} = 44,44 \thinspace \mu A \$

Hence,

\$ R_B = \frac{V_{CC} - V_{BE}}{I_B} \$

\$ R_B = \frac{9 - 0,7}{44,4444 \times 10^{-6}} \$

\$ R_B = 186,750 \$ ohms.

The problem is: when I put that on the simulator, it gives me a Vc equal to 4.24V, almost in the middle of the rail but not exactly and the worst part is that the simulator gives me a Vbe = 0.562V.

As far as I know, this silicon transistor will need 0.7V to work and the value from the simulator is not showing the whole thing will work as expected.

How are these calculations really done, taking into consideration differences from theory to the real world?


texts: Aperiod vs Period waveform Fourier Transform: How does nature understand which is the case?

texts:
Today I reviewed the theory behind the Fourier Transform, and I asked myself a question that I couldn't answer to in the process.

Theory: A periodic waveform has a Fourier series which can be seen as the sampling of the corresponding aperiodic waveform (i.e. the series of a square wave is the sampling of the transformation of a single rectangle).
So, a rectangle and a square wave have different harmonic components.

And now my question (square wave is just an example, the question is applicable to any aperiodic function): A digital driver (a clock generator if you want), drives a square wave at frequency f. It starts with a single "rectangle", its spectrum is that of the Fourier transform of a rectangle? Then it continues with many other - infinite - rectangles and you can say that it is indeed a periodic waveform (or at least it's been until that point), is its spectrum that of a square wave?

Of course, if I watch the signal with a spectrum analyzer I'll see the odd harmonics typical of a square wave... And it's absurd to say that the spectrum of the signal changes (initially that of a rectangle, and then that of a square wave). So what does really happen there?

I hope you see the incongruency that I'm trying to point out, and I would say this is not useless thinking as the spectrum of a signal says how the signal will propagate through the medium.

EDIT

From the comments it seems the question was not clear enough, let me add this:

"are you asking why you don't observe the spectrum changing in your analyzer between the 1st square wave and every subsequent square wave as it passes through?" --> My question is if this change really happens, and how it can make sense. If that really happened, it's clear why the spectrum analyzer would not show it.

EDIT 2: Clarify the meaning of rectangle and square wave

Also, when I refer to a "rectangle" or "single rectangle" I mean, basically, a single period of the square wave. To be more precise, the rising edge, high level and then falling edge are enough. Referring to it as a "square" didn't sound right to me. So I see a "square wave" as a series of "rectangles".


texts: How do you make a component only be on when a capacitor powers it?

texts:
I've been thinking and thinking about this.

Look at this image:

(Imagine both the resistor and LEd were in parallel with the capacitor, otherwise the LED will be overloaded)

By doing this I've managed to create a circuit that, when it loses power, makes the LED fade.
However, I wanted to find a way in which the LED will only be powered when the circuit doesn't have a power supply (other than the capacitor). I've been thinking about logic gates, diodes, etc., but can't figure out a way in which it would work. Is there any?


texts: Misunderstanding saturation and supply voltages in OP-AMP's

texts:
What concept am I misunderstanding in calculating circuit parameters given their supply voltages?

In the following example, the non-inverting voltage is solved with respect to the output voltage, where:

simulate this circuit – Schematic created using CircuitLab

  KCL @ A:
  $$ 0 = \frac{V_{A}-V_{S}}{30k} + \frac{V_{A}-0}{10k} \; \Rightarrow \; \therefore V_{A} = V_{B} = 0.25V_{S}$$
  KCL @ B:
  $$ 0 = \frac{(.25V_{S})-0}{4k} + \frac{(.25V_{S}) - V_{C}}{28k} \; \Rightarrow \; \therefore V_{C} = 2V_{S}$$

To find the range of values of $V_{S}$ where $V_{C}$ does not saturate, I apply the supply voltages:

$$ V_{C} = 8 \; \text{[v]}= 2V_{S} \; \Rightarrow \; \therefore V_{S} = 4 \; \text{[v]}$$

$$ V_{C} = 12 \; \text{[v]}= 2V_{S} \; \Rightarrow \; \therefore V_{S} = 6 \; \text{[v]}$$

However, the solution (and similar solutions) uses a negative saturation voltage (-12 [v]) instead of the positive value as drawn in the OP-AMP circuit - resulting in (-6 [v]) as opposed to (+6 [v]).

Am I misunderstanding sign conventions, or the fundamental application of supply voltages?

**For clarity: An edit was made to correct a mismatch between the unedited KCL equations and the circuit schematic - the leftmost 10k resistor was incorrect, and edited to its correct 30k value.  My apologies, but the original KCL equations, given solution, and question remain unchanged.


texts: How does a microcontroller "remember" a program?

texts: This is something thats really bugged me since I've graduated. We programmed PIC16f877a micrcontrollers in class but never got into the how it works, just the make it work. So let's say I write a program that makes LEDS flash in a specific order and send this program to the microcontroller through this special adapter to the right pins. What do you know, the LED's begin to flash as instructed. Now, I disconnect the power and remove the PIC from the breadboard. I put the PIC back in its correct spot, plug in the power, and the LED's still flash as previously programmed without having to reprogram it. How is this happening? How does this microcontroller essentially "remember" what I told it to do?


texts:
I am working on a 100 kWh capacity gravity battery bank.
How much suspended weight and how far down would it need to be lowered in order to generate 100 kWh?
How many kWh would it take to lift the weight back up?
What style of motor/generator can do this? It's being used both as the generator and the motor. Any thoughts on high torque direct drive?


texts: How can I monitor AC current in multiple wires with a single ammeter?

texts:
I'm looking for a cheap way to monitor my electricity consumption across multiple power plugs, on a per-wire basis (ie. I'm not looking for total power consumption across all wires)

There are many commercial products I can use either at the power plug level or directly in the electrical cabinet, but they are designed to monitor a single wire, and cost usually around $15, so monitoring multiple wires skyrockets the global price quite fast, not to mention the space issue for fitting all those ammeters.

Also, I would have to use multiple clamps in a small space, and I'm not sure this wouldn't cause unwanted artifacts in the measurements.

Is there an easy way to achieve this? I was thinking it should be possible to monitor a single wire and build a circuit to switch a different power cord on that wire every second or so. Is this a stupid idea, or does it make sense?

Or are there ammeters so small and cheap that it makes sense to connect one in series with every single fuse in my electrical cabinet?

I was considering building a prototype over a 12vac supply. Am I going to run into scaling issues when upgrading to 110 or 220vac?


texts: Protect circuit from current generated by backdriving DC motor

texts:
In our application we have two modes of vehicle operation: manual and autonomous. Meaning that when vehicle is operated autonomously we control a brushed DC-motor using an H-bridge. In manual mode we don't control it, DC motor will see high impedance on its leads and can be backdriven. So in manual mode we want as less resistance as possible to backdrive the motor and we want to protect our circuitry from charge generated by the motor and the motor itself. Is there a common practice for that?

Below is the relevant part of the circuitry that we are going to use to drive the motor, it consists of a gate driver and an H-bridge.


texts: Charging a LiPo Battery with 1.5V Battery

texts: I have a lithium-polymer battery with a voltage of 11.4V. If I want to charge it with a 1.5V power source (AA battery) and I boost the voltage to 11.7V will it slowly charge the LiPo.


texts: Mitigation of dead zones when applying circular polarized antenna

texts:
I would like to know if I used a circular polarized (RHCP) antenna inside a metal container as show in the configuration below will it reduce the dead zones, as compared to a linear polarized antenna?

From the research I have done when RHCP EM wave reflects of the metal surface it will become LHCP. It further went onto say that only when two RHCP EM waves "collide" will there exist dead zones due to destructive interference, where as if an RHCP collides with an LHCP then it can reduce these dead zones.


texts: PSD vs FFT of voltage magnitude squared and oscilloscopes

texts:
Imagine we have a time-domain signal which is a voltage signal. Now if we sample this at the correct rate, and taking the Fourier transform gives us the magnitudes of various frequency components present in the signal (within the context of sampling rate). Taking the modulus squared of this quantity will give us power/Hz, correct?

On the other hand, taking the Fourier transform of the autocorrelation function (rather than the direct transform as discussed earlier) gives the PSD in power/Hz as well.

So what is the difference between these two? Why/when should I do one over the other? Which method a digital scope use for its FFT function?


texts: PCM5102A: analog output level not what I expected?

texts:
I cannot achieve a 2.1 Vrms mentioned in their datasheet (pages 4 and 9). I can only output 1.04Vrms from the 1kHz source. Do I measure it wrong or this is what I should expect? Or maybe I get such measurements because it could possibly be a counterfeit chip?

PCM5102A schematic:

Update:

I tried to play different sine wave tone (0 dBFS) generated from Audiocheck and now I can see 1.88 Vrms and 5.64 Vpp when there is no load. Is this something I should expect? I'm playing this sound at the full volume over bluetooth since I use CSRA64215 chip as a source for PCM5102A. I also checked CSRA64215 config and it's output level is already set to max.


texts: What determines BLDC rotation direction when using trapezoidal commutation with BiPolar Switching?

texts:
Block commutation seems simple enough, the rotation is determined by the order in which the 6 step sequence is executed (ex. cw 1->6 or ccw 6->1)

What's confusing is how bipolar switching changes this. If you drive the low side phase with the same modulation that is applied on the high side, then this suddenly becomes bipolar, and it supports braking/regeneration all thru the pwm duty cycle (i.e. >50% is cw, <50% is ccw).

https://e2e.ti.com/blogs_/b/motordrivecontrol/archive/2012/04/04/so-which-pwm-technique-is-best-part-4

So how do these 2 non-mutually exclusive techniques (6 step trap & bipolar) reconcile with each other to determine the motor spin direction ?


texts: How can I control a CGA screen with an Arduino?

texts:
I'm getting one of these http://www.old-computers.com/museum/computer.asp?st=1&c=446

I'm planning to build a server inside it. And I was thinking of using the built in CGA-monitor as a statusdisplay (LCDInfo style, or whatever the cool geeks use nowadays).
The screen is monochrome amber so it would probably look a bit like the Planar EL-screens some have been using in their mods. And I want to use an Arduino (or something like it) as a middleware solution... PC -> Arduino -> Screen

I have been checking up a bit, and CGA is a RGBI signal using TTL-communications. 4 lines (RGB + Intensity), combined with HSYNC (15.75KHz) and VSYNC (60Hz).
The 4 "color-inputs" are logic on or off. The combination of these generates up to 16 colors. However, as this is an amber screen, it would probably be easiest to start with "all-high" or "all-low"... White and Black.

So the problem is the following... I could probably both wire and code the arduino to flip the TTL-lines on and off, but I'm not sure what I do with the HSYNC and VSYNC inputs. And how to time the TTL-flips to correspond to pixels on the screen. (The standard CGA resolution is 320x200).

I'm not very good at electronics, but I'm very good at following instructions, and taking hints

Has anyone tried this before?

EDIT:
Could I maybe use a modified version of this? http://www.eosystems.ro/deogen/deogen_en.html

EDIT2:
I don't need to use an Arduino. But I want to keep it as simple as possible.

EDIT3:
It might seem that the monitor in question actually is a composite monitor, and not a "real" CGA input monitor. So that probably makes things a bit easier. But I'm still interested in how to generate a pure CGA signal using a microcontroller...


texts:
I try to do a simulation on LTspice (simulation of the PA107DP amplifier from apex microtechnology) and during my simulation I noticed that I have a phase shift. so i want to see my bode diagram but i cant get it how could i do in this case?

and how I can choose its parameters. I have to base on what to fill them and to have my bode diagram


texts: Looking for the right LED driver, roughly 4V, 1.5W or 3W, 10-20Hz

texts:
I have bought 6 of the 20-string LEDs for a hobby project of mine. http://www.amazon.com/Warm-White-Lights-Silver-Wire/dp/B004E328A4/ref=pd_sim_hg_9

I wish to make them blink at a fixed frequency anywhere between 10Hz and 20Hz. I wish to use only one or two battery packs (3 to 6 AA batteries total) to power all 6 strings (the final circuit needs to be compact).

A single string of LEDs draws 120 mA of current. Fresh AA batteries supply 1.5 Volts each. So, each string should draw 3 * 1.5V * 0.12A = approx 0.5W per LED string.

I am looking for an LEd driver that will make the LEDs blink. My estimates is that I need 4 +/- 0.5 V, 1.5W or 3W +/- 20% for both, 15 +/-5 HZ LED driver.

I have tried a few searches and did not find anything that seems appropriate, probably because I am a beginner.

Please suggest a component. It should draw the same power as it modulates I assume it should not be bigger than a US quarter coin. Hopefully I have done my arithmetics right.

UPDATE:

I ended up using the 555 / astable circuit like this one: http://www.555-timer-circuits.com/flashing-led.html Here is a calculator I used: http://www.ohmslawcalculator.com/555_astable.php

So far so good.


texts:
I am working on a custom carrier board using a TI microcontroller as the master and an ADC IC as the slave. It appears that sometimes SCL will stay high when it shouldn't, almost like the master releases it. We only get this fault condition on a reset of the MCU (or total system power cycle) but it does not happen every time, maybe one out of ten on average.

Data transfer will be fine most of the time, until one of the unlucky resets causes the issues. You can see in the image below that after the address byte is sent SCL just goes high after a few clock pulses. Any ideas?


texts: How do I step down my voltage and up my current for a tethered drone

texts:
I'm fairly new to this platform but would like your advice on one of the projects that I'm working on.
I am currently working on adding a tethering system to the DJI S1000+ spreading wings octocopter to allow for 'unlimited flight time.'  I am planning on using a generator to supply AC current, a power supply to step the voltage down and switch to DC and then make use of DC-DC buck converters to step the voltage down and up the current.
However, I'm running into a lot of problems and I can't seem to  find the correct buck converters and power supply. The motors draw a lot of current - about 40A.


texts: How to read / write data into a S25FL064L flash memory?

texts:
I try to read / write data (single byte) into an S25FL064L SPI flash memory with an nRF52 based radio SoC. The datasheet says that I have to enable a write to nonvolatile memory by sending command code 0x06 and then I can use command code 0x12 to transmit up to 256 bytes to a given address.
// Write Enable for Nonvolatile data
Tx_Buffer[0] = S25FL064L_CMD_WRITE_ENABLE;
p_Device->p_CS(true);
p_Device->p_RW(&Tx_Buffer[0], 1, NULL, 0);
p_Device->p_CS(false);

// Read status register 1 -> will return 0x02 = write is enabled
uint8_t Rx_Buffer[2];
Tx_Buffer[0] = S25FL064L_CMD_RDSR1;
p_Device->p_CS(true);
p_Device->p_RW(&Tx_Buffer[0], 1, Rx_Buffer, 2);
p_Device->p_CS(false);

Tx_Buffer[0] = S25FL064L_CMD_4PP;
Tx_Buffer[1] = 0x00;
Tx_Buffer[2] = 0x00;
Tx_Buffer[3] = 0x00;
Tx_Buffer[4] = 0x00;
Tx_Buffer[5] = 0xF0;
Tx_Buffer[6] = 0xAA;

// Transmit the data
p_Device->p_CS(true);
p_Device->p_RW(Tx_Buffer, 7, NULL, 0);
p_Device->p_CS(false);

S25FL064L_WaitBusy(p_Device);

I just have to send the command code 0x13 to read the data from a given address:
Tx_Buffer[0] = S25FL064L_CMD_4READ;
Tx_Buffer[1] = 0x00;
Tx_Buffer[2] = 0x00;
Tx_Buffer[3] = 0x00;
Tx_Buffer[4] = 0x00;
p_Device->p_CS(true);
p_Device->p_RW(Tx_Buffer, 5, Rx_Buffer, 7);
p_Device->p_CS(false);

But the flash doesn´t transmit the data.
Write command

Read command

What might be wrong here?


texts:
To use the formula,
[Bf][Zb][Bf'][I] = [Bf][Zb][Is] - [Bf][Vs]
for the concerned, or any tree, should [Vs] and [Is], be written with respect to the directed tree I've taken, or with respect to the current direction in the loop? I mean the signs of the elements in [Vs] and [Is]...


texts: Arduino battery power stay on for button - Not quite working

texts:
I have been trying to get a circuit to work that would power an Arduino from a set of 4 18650 batteries. It needs to turn on with a button press, then stay on for 30 seconds, then completely power down.

My plan was to have the pushbutton connect the ground wire of the voltage regulator so it would be a physical switch to turn on power. Then in the logic of the Arduino turn on digital pin 5 right away and keeping it on until its ready to power down. That digital pin would control a mosfet which keep the power on.

I have the following components in my current almost, but not working scheme.

Arduino Nano
MP1584EN DC-DC 3A power Step-Down Amazon link
N-Channel MOSFET Digi-Key link
10k OHM Resistor
Pushbutton Image Link
330 OHM Resistor
4 18650 Batteries producing about 14v

In the following diagram the +14v and GND on the left side represent the battery connections.

I am using a 10k ohm resistor connecting the gate to the battery ground in order to pull it low so it does not float. I am using a 330ohm resistor between the gate and the digital pin on the Arduino for protection.

Everything seems fine until I plug in the Arduino to breadboard. That is I use my voltage tester to check that the Arduino VIN and GND pins do measure at 5v. Also if I press the button then connect a wire to the mosfet gate pin to my 5v rail the power does stay on. So it seams if I plug in the Arduino and it sets the digital pin high (5v) on the mosfet it would work.

Instead of working like I had hoped. There is a little smoke from the Arduino and its trashed. Another weird thing is if I have my voltage meter measuring the outputs of the voltage regulator, the output suddenly reads a much higher voltage. I was not sure where that change comes from, maybe its my voltage meter interacting with the voltage regulator in the Arduino. I found if I don't connect the mosfet drain to the battery ground the Arduino seems to work correctly, does not smoke and get fried, and I still get the weird high voltage reading. When the drain is connected the Arduino is instantly fried.

Any help would be greatly appreciated.


texts: Are datasheet min/max values "guaranteed" for the lifetime of the part?

texts:
In electronic parts datasheets we always see min/max values specified for voltages, currents, etc. together with the temperature ranges. Some values are tested by the manufacturer, some are specified as "guaranteed by design". However, are these min/max values for the specified temperature supposed to hold for the lifetime of the part? For example, if a supply current is given as min 10 mA and max 20 mA, with a typical of 15 mA for 25C operation, is this current expected to be within those ranges for the part's lifetime? If so, what is assumed to be the part's lifetime for which the datasheet is guaranteed: 1 year, 10 years? How can I find that information without having to ask each individual manufacturer?
EDIT:
To lead the discussion in a better direction and get to the main point of my question:
Let's suppose we set up a controlled environment where we guarantee the datasheet temperature is maintained (let's say room temp), with all the parameters meeting the spec at nominal values. How long am I supposed to assume that the datasheet min/max will be maintained? If parameters start drifting beyond min/max 1 year in, is that a violation of the datasheet? 10 years in? Where's the cutoff if there is any?
Thanks!


texts: Video compression using low power processor

texts:
I'm trying to build a hand held camera with video recording feature.

Basic features of camera are

Resolution: 640x480
Frame rate: 25/30Hz
Video format from sensor: 8-bit grey scale BT.656 (Sensor with Internal compression is not possible in our application).
Software platform: can be Operating system based/Bare metal coding depending on the decision taken on video compression part.
Expected Power consumption: 1.5 Watt for Recording circuit alone.
Storage: SD card

I'm using an avr micro controller for all the controlling and user interface of camera. However for the video compression and storage part I'm facing difficulty.

I have read lot of processors and controllers and found following things.

For the processors side i found that Texas instruments Davinci,OMAP,SITARA ,NXP i.Mx, and other media processor are relevant for my application.
But i feel that these are overkill for my application in terms of power consumption and processing power.
From the micro controller side  i have studied about atmel sam cortex m7 series with inbuilt video decoder and software jpeg encoder.  For video playback i can use hardware video decoder.
This option seems OK for just snapshot storage. But for video recording i need compression. Though the power consumption is low, the processing power required for video compression is not feasible with this as per my opinion.

The video quality I'm expecting is one which is reasonable for a surveillance camera.

I feel I'm missing something quite obvious for everyone except me in this world for such a typical application.

The main constraints I have are the power consumption and size.

Could any one suggest how I can go ahead for the video recording application.


texts:
One of my project architectures looks like this:

GPIO / 595 output / 12 VDC wire lengths will not exceed 25 cm.

I have faced MCU lockup issues due to EFT in the past and want to make sure this design is protected against all such threats.

This is what I intend to do for protecting my system:

1) Protection against surges - MOV on the input ac lines in the ac DC converter circuit which handles 4 kV surges. Do I need to do anything more besides this? I have heard that TVS diode offers better protection due to fast reaction time but MOV turns out to give best performance per unit money.

2) EFT/ESD - TVS diode (uni-directional) between 12V and GND at the entry point on main board (PCB which has MCU, 595 and relay). Uni-directional TVS diodes on all GPIOs leaving the board in form of wires.

There are some GPIOs that control 74HC595. Do I need to put TVS diodes on those GPIOs as well? Or should I put TVS diodes on the 595 output wires? Or both GPIO and output wires?

For DC lines, is uni-directional TVS diodes OK?

For such a system, what values of breakdown voltage, standoff voltage and peak power should I select? - for 12 VDC power line and 3.3 VDC GPIO lines.


texts: How do I use a switch without current running through it?

texts:
So there have been plenty of occasions where I would like to use a switch or even potentiometer in simple circuits I make (just little at home hobbyist creations). But alot of the switches I try to use are very limited on the current they can handle, especially potentiometers. My question is, how can I use switches or pots to interrupt a circuit without running current directly through the switch or pot? Is there a simple solution I'm just not seeing or grasping?
Updated to add info
Some examples are a homemade benchtop power supply that I would like to add a switch to each rail, but each rail has the ability to output upwards of 50 amps, which not many switches that I've seen can handle. Another example would include trying to add a momentary on push button switch to homemade "hot coil" lighter (the hot coil was a piece of graphite). The push button was rated for 3 amps which I clearly exceeded seeing as how it melted while testing it.


texts:
Okay I need to understand this concept because I'm playing with mains and I do not want to fry myself...
A little background : I'm quite good with low voltage stuff as well as logic level design but I've a big lack on switch mode power supplies . Due to a project requirement to implement a custom smps I've developed an unisolated one through the help of an engineer that works quite well (5v 0.4 amp).. leaving away the discussion about the unisolated power supply that goes into an abs encapsulated box with no end user interaction so it's perfectly safe and legally fine , I run into a problem ... as soon as I've connected the entire device to a serial converter , both burned out ... I've asked to my engineer what happened and he told me to run the device through an isolated 1:1 transformed to bring down the ground to earth ... we'll I'm actually a little lost , I understand that the neutral or hot wires becames the reference ground in my smps and that connecting them to a different ground that's on a different potential level may cause what I actually experienced , but I don't understand why my usb cable has earthed ground and why an isolation transformed changes the potential level on my input ac... I hope to have explained that in the right way !! Thanks !


texts:
I have a pot (R8), as you can see, C6 capacitor is connected to its middle terminal, I have trouble implementing this in Orcad as it says that the negative terminal of the capacitor is connected to nowhere, I tried placing a No Connect, it didn't work, then connected it to GND and the error went away.

But is connecting that terminal to GND technically correct or it would distort the result?


texts:
I am trying to target a specific page (script) on my webserver using a GPRS modem. I can hit my domain, and get a reply back but then when I am trying to call my script it just won't let me:

AT

OK
AT+CPIN?

+CPIN: READY

OK

AT+SFUN=SID

+ICCID: 54646149798787496

AT+CSQ

+CSQ: 16,99

OK

AT+AIPDCONT=“wap.rogers.com"

OK

AT+AIPA=1

+AIPA: 1,10.110.234.135,0,0,0 ;Connect with APN server

OK

AT+AIPO=1,,“www.Myserver.com”,80,0,,1

+AIPO: 1,“10.110.234.135”,4770,“74.125.227.17”,80,0,30,1,0,64000,8,7300,5720,-500,0)

OK

I am trying to hit either "MYSRVR.COM/SUB/PAGE.PY" or I can even do with "MYSRVR.COM/SUB/" if that's too much of a hassle.

Ref to AT commands/Data sheet


texts: What exactly does it mean when we say 'increase the transconductance of a mosfet'? What is the advantage of having a high transconductance mosfet?


texts:
I need help with the following homework problem.

What I have done so far ......
Data
Voltage Supplied= 50V
Load Voltage= 50/3 = 16.66V
R1=?
R2=?
RL=?
P(Load) = 1.0 mW
VR1=?
VR2=?
IR1=?
IR2=?
IRL=?
Solution
Finding RL
P=V^2/RL
RL= V^2/P
RL= (16.66)^2/1.0 mW
RL=277.5 kilo ohms
VL=VR2=16.66V
VR1=50V-16.66V=33.34V
IRL=VL/RL
IRL=16.66/277.5
IRL=0.0600mA
IR1,IR2,R1 And R2 ?


texts: How to automatically "normalise" a voltage signal in LTspice?

texts:
I would like to create an output signal that is normalised by the maximum value of a signal in LTspice. This is to produce a signal between [-1, 1] that is suitable for producing a wave file like found here i.e.

  .wave "z:/home/runejuhl/out3.wav" 16 44100 out1

Signals will clip the wav file if they exceed a magnitude of 1.

Currently I am using a voltage controlled voltage source to reduce the overall level by a constant factor:

This works ok, but doesn't maximally utilise the range of [-1, 1], and requires manual adjustment to adapt to changes in signal level.

I would like to set the gain factor such that it is equal to 1/max(Vout). Completing this in a single analysis command seems impossible as it would introduce a delay-free loop, the normalisation factor would be dependent upon something currently being calculated.

Is it possible to calculate a value from one simulation and use that in a following simulation? Preferably automatically without having to manually perform the calculation and place the result in the schematic.


texts: What is wrong with my 50 Ω grounded coplanar waveguide?

texts:
I've been working on a 4-layer design built around the EFR32BG13 Bluetooth Low Energy SoC. While trying to measure the impedance of the antenna to build a matching circuit, I discovered that my short grounded coplanar waveguide (GCPW) transmission line was acting more like an antenna than a transmission line.

To narrow down the cause of the issue, I built a simple 4-layer transmission line test board, which is pictured here:

The board is 100 mm square. I had these boards fabricated by ALLPCB, who specify 35 μm copper on all layers and 0.175 mm dielectric (dielectric constant 4.29) between the first two layers. Using AppCAD, I found that a design with 0.35 mm trace width and 0.25 mm gap yields an impedance of 48.5 Ω. The top layer for the board is shown in red above. The other three layers are ground planes that look like this:

I received the boards today and began by testing S21 for the second section from the bottom--a straight piece of GCPW with SMA connectors on either end. I used an HP 8753C / HP 85047A with a short length of coax connected to Ports 1 and 2 and the test board connected between those lengths of coax. Much to my surprise, this is what I saw:

At 2.45 GHz, my transmission line has a response of -10 dB. If I replace the board with a "thru" connector, I see exactly what I would expect:

I'm at a bit of a loss, as I thought that the first test would be a slam dunk and I would start finding issues with the more complex tests above it. I have a VNA and a strong desire to learn what I'm doing wrong here. Can you see any problems with my testing method or with the GCPW design itself? Any help at all would be greatly appreciated!

Edit: As suggested by Neil_UK, I have removed the thermals on one board by scraping away solder mask and then bridging the gap with solder. Measuring S11 and S21 with this configuration gives the following result:

Comparing the S21 plot with the previous result, there does not seem to be any perceptible difference.

Edit 2: As suggested by mkeith, I have split one of the "strips" of my test board apart from the rest using the old "score and break" method. The board I chose to break off is the same board I removed thermals on, so this result is a further modification on the preceding plot. Here it is:

There is a deepening of the troughs in the S11 plot, but no significant improvement in the board's functionality as a transmission line.

Edit 3: Here is a photo of the board in its most recent embodiment:

Edit 4: Close-up shots of both sides of one SMA connector:

The SMA connector is Molex 0732511150. The PCB land follows the recommendations in the datasheet here:

http://www.molex.com/pdm_docs/sd/732511150_sd.pdf

Edit 5: Here is a cross-section of the board near one edge:

The green lines are scaled from the manufacturer's specifications, which are copied here:

Edit 6: Here is a top-down photo of the board with red scale lines showing the expected dimensions:

Edit 7: To verify the effect of the large center SMA land, I carved away the central pad on one board so that it was the same width as the rest of the trace. Then I used copper tape to extend the grounds on either side:

Then I retested S11 and S21:

This seems to have improved S11 significantly, which leads me to believe that the large center land was, in fact, creating a capacitance at either end of the line resulting in resonance.

Edit 8: Looking for some guidance on how to handle the transition from SMA to GCPW, I came across this white paper:

http://www.mouser.com/pdfdocs/Emerson_WhitePaperHiFreqSMAEndLaunch.pdf

While the paper specifically refers to the use of a high frequency substrate, I think much of it is still applicable here. Two main points stand out for me:

The GCPW should continue all the way to the edge of the board.
High frequency end launch SMA connectors use a center pin that is shorter and narrower to minimize its effect on the GCPW. These may be more appropriate for an application like this with a thin central conductor on the transmission line.


texts: Can I use this high-side driver with arduino?

texts:
I have salvaged a PCB with quite few single and multi-channel high side drivers. One of the is VN5E010AH. If I understood datasheet, this chip can drive high voltage using low voltage cmos compatible input. The reason I am interested in using this chip is analog current sense (5V max out).

Would this work with arduino, and what is cmos compatible input?


texts: Soft-on/off circuit turns on on startup despite being jumpered to stay off, why?

texts:
So, I am building the soft-on/off circuit shown below and described here on a breadboard to test it out before I actually put it into a design.

However, to better fit the parts on hand, I decided to alter a couple of the R and C values slightly, and use a pair of TO-220 FETs instead of the SO-8 dual FET, resulting in this:

simulate this circuit – Schematic created using CircuitLab

which yields the simulation results below when turned on without RL connected (NFG tracks Vout in both plots, so it's not shown):

and with RL connected for a 10mA load at full Vout (PFG, Vin, and PB track each other here):

However, when I prototype the same circuit that's in the simulation, without a load, I get this gem of a result on power-on:

Along with that, Vout comes up to a steady 12V, tracking Vin.  What in the world could I have done wrong here?  Is the circuit given really that sensitive to part selection?  Or how could I have miswired it to produce the results I'm receiving?  And where on Earth is that 370us pulse on PFG at startup coming from?


texts:
For a school project I'd like to put a "fit pc 2" (a  RaspberryPi-like) on a flying device.
As the fit PC2 is supposed to be directly plugged  to energy, I'd like to buy a battery to let it work in the air.

I have the folowing information written on the fit pc 2 box :

Input: DC12V (9V to 15V tolerant)
Adaptater: AC100-240V -> 12V 1.5A

I found the flowing  battery :
http://www.selectronic.fr/media/pdf/6345-7-fiche-technique.pdf

It says "NX - 12V - 2.9Ah - 98.5x79x55.5mm". As far as I understand this would work and let me use the computer for a theoretically 2hours.

Is this right ? Should I only care about making it 12V and n*1.5 Ah (n being how much hours I want the battery to last) or is there any other characteristics I should take into consideration ?

Needless to say I'm far from being good in Electrical Engineering... ;)


texts: activating an EC2-3TNU with the VT pin of an HT12D

texts:
I am sending a signal from an HT12E through an rf transmitter to an rf receiver then an HT12D. This all works fine and the data signal from the HT12D is sent to a CZH-LABS D-1022A(for filling a pool). The pulse triggers the relay on the CHZ so that works ok. What I want to do is take the same pulse/signal from the HT12D and send it through a 3vdc regulator (it is currently at 5vdc) and then through an EC2-3TNU latching relay. The relay would then turn on power to an ESP12E, which would connect to the wifi and send a message to ThingSpeak that the original signal was received and the pool filling relay triggered. The problem is that even though the signal from the HT12D reads 3vdc and it lights up an LED light when the signal is received, it doesn't trigger the latching relay. I am attaching a schematic to show the wiring of my project.

To summarize: The 5vdc (converted to 3vdc) signal from the HT12D will light up an LED but won't trigger a 3vdc latching relay EC2-3TNU. I thought I may be the size of the smoothing capacitor after the center tap rectifier, but if I connect the ESP12E up to 3vdc and the activate the signal the LED still lights up but the latching relay won't engage.

I found online that I don't have enough current from the VT on the HT12D. It only has 1.6ma whereas the EC2-3TNU needs 48ma.  It was suggested I use a transistor so I found a schematic and explanation for one and tried it but it doesn't seem to work.  Not sure if it work only with single non-latching relays and the EC2-3TNU is a duel coil latching relay.  I am including a schematic of my set up for all to look at and give me suggestions.


texts: Frequency-dependent behavior of R and L in LTspice

texts:
I have this question that I have been dealing with for quite some time now.
Say I have an electrical machine that I model using lumped parameter (RLC circuit). As we all know, R and L are frequency-dependent (R because of skin and proximity effects, L because of the presence of the magnetic material). I want to simulate the frequency-dependent behavior of the machine in LTspice but .TRANS simulation will not work because, like I have learned here, Laplace function does not exhibit reliable outputs when it is used in .TRANS simulations, whereas, for .ac, it works just fine.
The problem I am having with .ac simulation is that it is generally used to measure the impedance of the system. For my case study, I am more interested in the distribution of the voltages in some nodes of interest, when the machine is supplied with a trapezoidal waveform voltage (or other weirdly shaped voltages with a very wide spectrum). I am trying to analyze my circuit in frequency domain and output the spectrum of all the currents and voltages that I want. Hope I was as clear as possible.


texts:
thanks you in advance for any assistance. I am converting this old AM radio into a bluetooth speaker with an echo dot built in for my 11yo daughter.

I removed the inner hardware and tubes. Wow beautiful stuff.

I purchased this amplifier to run the speakers. I set it up using a 12V 1amp power supply I had on hand. The amp with the speakers sounds great.
link to amplifier

What I need is a reduction in the 12v down to 5v so I can run the echo dot, it has a USB connection.

I am looking for a plug-and-play option. Would this work?
LM2596 DC to DC Step

Thanks again for any help, apologize for my ignorance.


texts: Howto convert "0=floating / 1=Vcc" to CMOS compatible "0=ground / 1=Vcc" signal

texts:
I'm playing around with CMOS logic using CD#### dip packages. As far I understand input pins should never be left floating, always connect them to Vcc or ground. Unfortunately my digital source encodes "1" and "0" respectively by Vcc and floating pins. How can I properly connect such signal to CMOS logic?

Apologies for the incorrect terminology!


texts:
Out of curiosity, is it possible to have a current source generating extremely high current? In the magnitude of 100kA? With low voltage output since the resistance would be 0.1 micro-ohms.

It's very rare to find, I guess due to the fact that there aren't any useful applications that would use high current in that range without completely melting(maybe a single turn loop to generate high magnetic fields for a short duration of time), what would the power source be? Capacitors, a generator, from an engineering stand point, it seems an extremely difficult task.

An interesting attempt.


texts:
I don't understand current sources!  Batteries are voltage sources, but how does one actually implement a current source?  I was looking at current mirrors to see how they work, and I understand the idea of getting a nearly identical current produced by the other half, but on the diagrams where is the current I_ref coming from?  Is that just a voltage source across a resistor?  Also, how could I use this to drive a load that was attached to M2's drain?

I appreciate any explanation!


texts:
I'm dealing with a small automation project, a rack and pinion system controlled by an Arduino card with two limit switches to ensure that the rack moves within the boundaries.
I have been trying both photointerrupters and hall-effect switches and both of them seems working without problems.
Which sensor should I use if I need to prioritize reliability and correct functioning in time?
I heard that optical sensors are sensible to environmental light, dust and aging. Which are the minus points of an hall-effect switch?
In this case I mean a unipolar hall-effect switch, will all the logic already build in, and that it can be connected to a microcontroller with a simple pull-up resistor.


texts: Can USART TX on the STM32f4 be open-drain?

texts:
I'm retrofitting an old project, moving a Discovery Board from an isolated ground to a non-isolated ground, and it's shifting around all my power supplies.

This will be interfacing with a 5V device that probably won't deal well with a 3V TX from the Discovery.  I'm using USART3 on C10 and C11, which are 5V tolerant, so RX shouldn't be an issue.  Now, since the level shift is no longer handled by my isolator, I'm just trying to find out if I can get away with an open drain output and a pull up resistor for TX, or do I need to use a more elaborate level shifter.  Seems like it shouldn't be an issue, but every usart example I've seen on for UART on STM32F4 using Push/Pull outs.

UPDATE:
This worked just fine.  I bench tested, and didn't see any problems.  Once I actually had everything hooked up,  it seems like something on the output had a bigger capacitive load than my bench test, impacting my TX at my  megabaud rate, but lowering the pullup resistor fixed this.


texts: How can I configure the FTDI FT220x for multiple SPI slaves?

texts:
I'm using a UM220XB development module to breadboard the FT220X.

My design uses the FT220X to connect my microcontroller to a PC via SPI. My circuit design has 2 SPI slaves and 1 SPI master on the bus.

This is my problem: The FT220X, by default, drives MISO and MOSI even when #CS is not active.  This causes bus contention if there are multiple SPI slaves on the bus.

These FTDI chips have onboard EEPROM that can be used to configure them.  You can use a utility called FT_PROG.

The datasheet claims that FT220X supports multi-slave SPI bus.  It claims I can reconfigure the EEPROM to change the behaviour of MISO and MOSI.  Supposedly, you can use FT_PROG to make these lines IDLE for use with another slave on SPI bus.

Here is the quote from the datasheet (page 14):

  Additionally, the FT1248 slave block supports multiple slave devices where a master can communicate with multiple SPI slave devices. When the slave is sharing buses with other SPI slave devices, the write and read buffer status cannot be reflected on the MIOSIO[0] and MISO wires during CS# inactivity as this would cause bus contention. Therefore, it is possible for the user to select whether they wish to have the buffer status switched on or off during inactivity.
  (This setting may be applied in the internal MTP memory with FT_PROG at the same time as selecting FT1248 mode).

I am able to successfully read and program the device EEPROM with FT_PROG.
The PC detects the module and assigns a VCP.  I have been through the FT_PROG menus, the FT_PROG user manual, the UM220XB manual, and the FT220X manual.  But I cannot figure out how to change this setting.  Nowhere in FT_PROG can I find a setting like this.  Help please!


texts: How and where is energy dissipated in a driven traction motor?

texts:
When a fully loaded elevator is moving down its potential energy is decreased and I guess is somehow converted by the elevator traction motor into heat.

How exactly does it happen? What exact elements of the motor or other parts do the conversion and how?


texts: MOSFET half-bridge taking too much time to close

texts:
I'm using IR2104 to drive two N-MOSFET, 2KHz with very low duty. IR2104 is a half-bridge driver with fixed deadtime:

This is the gate driver output without MOSFET:

This is the MOSFET gate when working:

As you can see, it's taking longer for the MOSFET ti shut down than the deadtime.
Why the MOSFET won't shutdown immediately and what can I do to make it shutdown within deadtime ?

Thanks in advance !


texts: Transistor functionality in a given schematic

texts: Can anyone tell me what is the functionality of the transistor in this schematic ?


texts: Question on power consumption on S32K1xx

texts:
I am using this microcontroller - S32K142 - 64 pins. Core voltage: 5V
I want to know whether the oscillator that we use for the controller would consume any current.
If it consumes current, how to find that? I was not able to find it in the mentioned datasheet.
Question 1 :
Suppose, I use this 8MHz resonator between the pins 11 and 12, how to determine the current consumption due to this resonator?
Question 2 :
What would be the case if I use the internal 48MHz FIRC or some other oscillator?
EDIT :
Question 3 :
Suppose I use the 112MHz as the core clock frequency of the microcontroller i.e.HSRUN mode, from Table 13,I get that, at 25degC, the current due to the oscillator is 112*360uA = 40.32mA?  Isn't this a very high value? Am I correct in calculating the oscillator current, this way?
So, If I enable all the peripherals in HSRUN mode, my total microcontroller current consumption would be 52.2mA+40.32mA = 92.52mA. Is this correct?
But I am confused like, what about the current consumption due to FIRC usage(suppose if I use FIRC clock source also)? Suppose, I also use the FIRC module for some other peripherals, say like SPI at 48MHz. What would be the current consumption due to the FIRC module usage? Would it be 48*360uA = 17.28mA?
The 40.32mA current was only due to the HSRUN mode which derived its frequency from the external resonator of 8MHz and upconverted to 112MHz by the SPLL. So, should I add both the currents as I am using 2 different clock sources (FIRC and SPLL)?
Please help to clarify - to calculate the current consumption due to different clock source (FIRC and SPLL) module usage and peripheral module usages?


texts: Design and analysis of Two inductor boost converter

texts: how to decide inductance values in case of two inductor boost converter?


texts:
I am using the MSP-EXP430F5438 evaluation board, which has pushbuttons connected to P2.6 and P2.7 and LEDs connected to P1.0 and P1.1.

I want to make it such that P2.6 sets the LEDs on and P2.7 resets them. To do that, I wrote the following code:

#include  "msp430x54x.h"

int main(void)
{
          WDTCTL = WDTPW + WDTHOLD;             // Stop watchdog timer
          P1DIR |= BIT0 + BIT1;                 // Set P1.0 and P1.1 to output direction
          P2DIR = 0x00;                         // Set the P2 to input direction

          P1OUT = 0x00; // Blank all LEDs

          while(1)
         {
            if(P2IN & 0x40) // When P2.6 is pushed
              P1OUT = 0x03;
            if(P2IN & 0x80) // When P2.7 is pushed
              P1OUT = 0x00;
            __delay_cycles(100000);
         }
}

But it doesn't work properly; sometimes it works erratically (the LEDs turn on when P2.6 is pressed but they don't turn off when P2.7 is pressed), sometimes it doesn't work at all.

Any ideas?


texts: Is this op amp circuit using both negative and positive feedback?

texts:
In this question/answer theres this op-amp circuit:

I can't work out whats happening. At a glance the op-amp circuit looks like a cross between a schmitt trigger, differential amplifier and possibly an oscillator! Help!

What is it? What could ut be used for? How does it work? Please assume working knowledge of op-amps but not harder math such as calculus, transfer functions etc


texts: Strange NTC behaviour: it goes open circuit when cooling down

texts:
My partner has a heater for heating wax that is used for waxing legs and other body parts. She told me it stopped working; it does not heat up anymore.

When I opened the device and looked at it I found that the temperature is controlled by an NTC. When I measured its value, my meter said that it is open-circuit.

However, when I heat the NTC with a hot air gun, its resistance drops to a few kOhm.

When I let it cool down, its resistance increases and when it reaches 32 kOhm, it suddenly goes open-circuit.

I've repeated the heating and cooling cycle a few times to make sure that it isn't a fluke (although I am using a Fluke multimeter).

I've never seen an NTC behave like this; the resistance normally increases until it reaches its nominal value at room temperature.

Is this a special NTC or is it just broken?

I haven't been able to look at the NTC itself, because it is built into the device and I don't want to take it further apart unless I am pretty confident that the NTC is broken and needs replacing.

The NTC is soldered to two leads and is inside heat-shrink. The assembly is wrapped in transparent light-brown-yellowish adhesive tape. I assume that this is heat-resistant adhesive tape.


texts:
I am building a circuit that needs to operate on +10V and -10V DC, and of course, a ground connection. It should be good enough to deliver just 1 amp. If I use a 120V to 10V AC transformer along with a bridge rectifier and capacitors, I should expect around +-13V DC. I will then use regulators to get it down to the voltage I need. Here is a quick power supply I threw together.

simulate this circuit – Schematic created using CircuitLab

Now, while this solution does work, I don't want a bulky transformer either internally nor externally of the device. Is there any easier way to do this that would work with either an AC or DC wall-power barrel connector? Or will I have to stick to this circuit to get the -10V?
I'll stick close by to answer any questions you may have to help me come up with an ideal solution. Thanks!


texts: VHDL: Why does my code not work for an asynchronous reset?

texts:
Below is one of my processes I have that I wrote in a control unit block that is interfacing with an FPGA board. The entire program basically implement a stopwatch.

I tried to implement an asynchronous reset in this process. My original code did not work in resetting the stopwatch. However, this new version works, and I don't understand why.

controlProc: process(clk, reset)
begin
    if (reset = '1') then
        pstate <= S1;
    elsif (clk'event and clk = '1') then
            --if (reset = '1') then      <----- This is my old code commented out.
                --pstate <= S1;          <-----
            -- Do Stuff
    end if;
end process;

Here is my original code

controlProc: process(clk, reset)
begin
    if (clk'event and clk = '1') then
            if (reset = '1') then
                pstate <= S1;
            end if;
            -- Do Stuff
    end if;
end process;


texts: How to connect a pulled motor from a printer to Breadboard and control with raspberry pi?

texts:
I managed to salvage a couple of motors from a worn down old printer, and I'm unsure of how to get about connecting it to a breadboard and then to a Raspberry Pi. I've got a cobbler kit for my Pi that allows me to connect it up to the breadboard. I'm also unsure about what kind of motor it is, DC or Stepper.
The motor looks like: http://imgur.com/a/PLmKw

Thanks!


texts: Arduino MEGA 2650 R3 pin 13 LED is always on, unless I connect a multi-meter

texts:
I have a problem with the on-board LED staying lit up despite running a blink program.

I was running the blink program below, which writes HIGH/LOW to pin 13, but the light was solid. As soon as I connected the circuit between ground and pin 13 with the multi-meter, the LED started blinking.

Here's a video showing my setup. The video shows the "L" LED lit solid. The digital multi-meter (connected to pin 13 and GND) is switched from OFF to DCV, at which point the LED starts to blink. The wire connections are removed, and the LED is again lit up solid.

When the pin is set HIGH, the voltage reading is 5.07V. However, when the pin is set LOW, the voltage reads 0.61V whereas other pins read 100 times less, around 6mV.

void setup() {
  pinMode(13, OUTPUT);
}
void loop() {
  digitalWrite(13, HIGH);
  delay(2000);
  digitalWrite(13, LOW);
  delay(2000);
}

The question is why is this happening? Is my board bugged?

Reference schematic linked here. "arduino-mega2560_R3-sch.pdf"


texts: Am I using my multimeter correctly to measure current?

texts:
I've wired up a simple circuit using:

9V Battery
Blue LED
220 Ohm Resistor

I was expecting a much higher value of mA? Is it true it's only 0.8mA?
Shouldn't the LED light up, since we're closing the circuit with our multimeter?

Thank you!


texts: gain, bandwidth and GBWP of current to voltage converter with op-amp

texts:
It might be a silly question since I am new to circuits and have little knowledge about it.
I've learned that gain of a current to voltage convertor with op-amp is determined by feedback resistor R in the following figure:

Let's say I'm using an op-amp with GBWP of 10 MHz and using a feedback resistor of 47 kOhms.
In this situation, will available bandwidth be 10M/47k = 212.xxx MHz ?
I am a bit confused that it is ok to regard it as a general concept of gain in other amplifying circuit.

In the figure above, gain is determined as 1 + R2 / R1 or R2 / R1 which is generally and practically 0 < gain <= 100... something. It is much smaller than a resistance, 47 k.
Is what I said is correct, or am I missing something and there are something I didn't know?


texts: Operating a switch mode power supply at its limits

texts:
I have a few SMPSs with over current protection.

When reaching the maximum power output they simply start dropping the voltage.

I am powering LEDs and the alternative would be to add a small resistor in series.  The power heating the resistor would however be lost.

Is it safe and power efficient to operate SMPS at their limits?

If this depends on the PS (maybe the IC) is there an easy way to know which PSs I can use this way and which not?

If it's not safe / power efficient, why?


texts: LTspice: reverse biased diode fails in ac analysis

texts:
I want to read out the diode saturation current with ac analysis. In this example, 100uA. Hence I bias the diode at -1V where the diode current is effectively the saturation current (*-1). It works with .op analysis but fails with .ac analysis: As can be seen, the result is basically zero:

(It does not work with I(D2) either).
WHY?
PS: This is just a simplified test which is part of a larger simulation in which I need to sweep over different Id values. Since I cannot parameterize this, I create multiple .model statements with nunmerical values and sweep over them. However, in order to plot versus the actual Is values (as opposed to the numerical IDs of the model) I need to read out the saturation current for each step.
EDIT: I think I know why: The Is I am looking for is the large signal value. It gets discarded in the small signal ac-analysis. Then the question is: How can I obain "Is" of a diode from an ac-analysis?


texts: How To Hide The Outline of The Polygon in Altium

texts:
I have copied a polygon pour from one PCB to another, but I cannot seem to hide the outline on the new board. Anyone know how to do this? Comparison below:

New Board:

Previous:


texts: Does current matter for high/low input in circuits?

texts:
I am trying to figure out a good way to word this question, but I don't think my electronics vocabulary has yet matured enough to use the correct terms. I'm working with building simple circuits on a Raspberry Pi for the first time.

To start, I understand that the input and output pins on the Pi read out a value of either 0 or 1 depending on if the voltage applied to them is either high or low, relative to ground.

I also know that if you build a circuit in parallel, then each branch of that circuit will have the same voltage as the potential source, but with a lower current.

Thus, I got to wondering: if you had a single pin output, for example, 3.3V, and had it split in a parallel circuit of very many branches, so that the current in each branch became extremely small, would the equal amount of input pins connected to each of the branches still recognize a high or low signal?

Basically, does it matter whether the current in a high/low signal is 3mA or 0.0003mA? Is the voltage the only thing that matters?


texts:
I have an AVR Dragon and several AVR MCUs. I recently purchased a BeagleBone Black (Cortex-A8). I'm trying to write my own bootloader. However, this would require a programmer.

Can I use an AVR MCU to be the medium to communicate between a USB port and a JTAG port? If so, how would I do it? Do I simply redirect the data stream? Is there anything else I need to implement in order to make it work?


texts: How can i make the pulse at V2 shift by 180 degrees in order to make it a negative 7.2 symbol for H bridge motor

texts:
This is the circuit I built in Lt spice. The NMOSFETS I downloaded online  have 1,2,3 automatically i cant change the label. 1= drain, 2 = gate, 3= source.
This is the result i get

However i need to get a reuslt similar to the image attached below but instead of 15v it needs to be plus and minus 7.2V. What changes can i make to my circuit to achieve this.


texts: Question about Biot Savart Law using vectors

texts:
This is a Biot savart law question using vectors and I tried this question and I want to check my answer is correct or not. And please show me the correct answer if wrong. I uploaded my Answer.

Question

My answer


texts: Arduino Nano ISP turns into the target program (as well as target MCU)

texts:
I'm trying to use a Nano V3 clone as an ISP to program atmega328p's because I have not dedicated programmer yet. As part of troubleshooting I'm just trying to program another breakout board with ISP headers with something simple as the example Blink sketch. Everything seems to go fine as far:

I can upload the programmer sketch to the programmer Nano
The program is running fine with a pulsating heartbeat
I can program the target breakout with the Blink sketch using Arduino IDE

However, here the bad stuff occurs - The programmer Nano ALSO turns into Blink:

https://photos.google.com/photo/AF1QipMNj2wmq_h_MR-qT5HvR7pq6VMZ7ltLyJ8zhVHv

I can actually workaround by just changing back to AVRISP mk2 and uploading the ArduinoISP sketch again and then the programmer Nano is an ISP programmer again and the other one still Blink. But it's just weird and I really don't want that as part of my workflow and maybe I have other issues due to this that I don't understand.

To be super clear on my setup:

I'm on OSX, connecting a usb cable to a Nano V3 clone. I've uploaded the 'ArduinoISP' example sketch as of Arduino IDE 1.8.5 (I think it has been updated recently)
The Nano seems is running this sketch - the heartbeat is pulsating
I connect 5 of the 6 pins on ISP 1-1, everything but the reset which I connect from D10 on programmer to reset on ISP header of target - all according to instructions.
I change the programmer in Arduino IDE to be 'Arduino as ISP' and leave everything else intact, port - same usb port, processor - still atmega328p, board - still arduino nano.
upload Blink

This makes the programmer turn into Blink too.


texts: If I am laying out two switch mode power supplies right next to one another from the same supply(24V), one is switching to 5V and the other to 12V then do I need both of the input capacitors? Thanks


texts: DDR Trace Length Inside Package from Simulation Model

texts:
The DDR4 in question is a Micron MT40A512M16JY. From the vendor site, you can get the datasheets, specs, sim models. I assume from the sim models you should be able to see the trace length of each signal pin inside the package. But I can't figure out how to interpret the files. Anybody knows how to read those sim models manually? If it is not in the sim models, where to find out those lengths?

I know that I do not have the skill to run the sim model with HiSpice tool. The purpose of this question is to compute trace length alignment in layout. So I just need a way to know the length of each signal.


texts:
I am stuck on a homework problem that I have difficult time understanding:

  Draw the state diagram of the circuit described below, with detailed
  explanations:

  A detection circuit has two inputs, x1 and x2, such that an output z
  will become 1 as soon as 4 consecutive input pulses are received and
  the 4-bit sequence contained at least two x1 pulses.  Assume the
  sequences consisting x1 and x2 may not overlap.

Could anyone clarify this question for me? Does a "pulse" by definition means when an input goes from 0 to 1, then to 0?  When it says "4 consecutive input pulses" does it mean for both inputs, x1 and x2?  I am not getting the whole picture together...


texts: Amplifier and Low Pass filter not responding after few minutes of correct output?

texts:
I am trying to design an amplifier and low pass filter circuit for a piezo sensor.

My frequency of interest is .3 Hz to 5 Hz, for first stage I have used charge amplifier and the subsequent 3 stages in combination is 6 order low pass filter.

For initial few minutes the response is fine (as desired) but after sometime signal dies off and there is no result at any of the stage.

Input supply is 5V and Vdd reference voltage is 3.3V.


texts: Why are CPUs becoming smaller and smaller?

texts:
It is a known fact that over time processors (or chips) are becoming smaller and smaller. Intel and AMD are in a race for the smallest standards (45nm, 32nm, 18nm, ..). But why is it so important to have the smallest elements on the smallest chip area?

Why not make a 90nm 5x5cm cpu? Why squeeze 6 cores into a 216mm2 area? It will be easier to dissipate the heat from larger area, manufacturing will require less precise (and thus cheaper) technology.

I can think of few reasons:

less size means more chips could be made on single wafer (but wafers aren't very expensive, right?)
smaller sizes are important for mobile gadgets (but everyday PCs still use tower boxes)
small size is dictated by light-speed limit, the chip can't be larger than the distance an EM field can travel in 1 cycle (but thats approximately several cm at 3GHz)

So, why do chips need to become smaller and smaller?


texts: What is meant by 'local' in local oscillator?

texts:
We know that a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal.

But what do we mean by 'local'?
How is 'local oscillator' different from normal oscillator?
Why can't a normal oscillator, like an LC-tank circuit or an opamp circuit, be used in a heterodyne receiver?


texts:
In Kicad, the PCB layout / schematic editor I use there is an option to export Gerbers in 4.5 or 4.6 format. I can not find any documentation on what this means.
Any help would be appreciated.


texts: I'm using the TP4056 to charge a LiPo cell in my project. I want to use the ICs pins 6 and 7 and connect them to the ATMEL Atmega328p digital pins 11 and 12 (pins D7 and D8 on Arduino board) and use these pin to sense when the device is charging and when the battery is full. The input to VCC is 5V and the LEDs used in the circuit have a Vf 2.0V.


texts:
What is the algorithm used in charging lipo batteries?

From watching my charger, I see that the amperage is close to the maximum specified (i.e. what I keyed in) at the beginning and gets smaller as each cell nears its maximum charge, but I haven't noticed a direct correlation between the cell voltage and input amperage.

Is there some "standard" algorithm, or does each charger manufacturer implement their own?


texts:
I'm trying to put together a project with some bright LEDs but I'm not sure how to control them.  Ideally I'd like to drive about 64 of these LEDs that have a forward current of 300mA and voltage drop of between 2.2V and 3.4V.  I'm looking for something similar to the MAX7221 I think but one that can support these high currents.  Does anyone have any ideas or experience with driving these kind of LEDs.  I'd like to use arduino to control the driver.

I came across the LT3492, would that work?


texts: Some schematic voltage values (physical names) missed when printed or generated in Altium

texts:
Maybe it's a silly issue, but the fact is that I don' t know why a voltage value is present in the schem project document but it will disappear from the destination document (printed or generated) at placed power port elements.

More strange issue is that it is not happening to every power port name. Some ports keeps the voltage value.

It' s something strange, but I would like to show all the port values on output documents. So I would like to know what the issue is and try to fix it.

Left picture is the schem view in project with name.schDoc. If I print it directly or if I generate a schem output file, hence, right pict you will see.

Someone says it could be an Altium bug. But I will ask for people here, hopping that someone face the same issue sometime and they could solve it.

Any trick to see the "removed" names when printing? Any information will be apreciated.

Thank you in advance!


texts: Can A HP8756A Network Analyzer Measure The Resonant Frequency Of A GPS Chip Antenna?

texts:
I'm wondering if a HP8756A network analyzer by itself is enough to measure the resonant frequency of a GPS chip antenna?

The reason I am concerned that it cannot is because I cannot see a "RF Out" connector on the front panel. I hired a portable NWA last time I wanted to measure the resonant frequency, and it had a "RF Out" connector on it. Does the HP8756A require an external "sweeper" (more costly hardware) to generate the RF signal?

An example of a HP8756A is http://www.ebay.com/itm/Agilent-HP-8757A-10-MHz-100-GHz-Scalar-Network-Analyzer-/131016149080?pt=LH_DefaultDomain_0&hash=item1e812bc858

The manual for the HP8756A can be found at http://www.teknetelectronics.com/ManualsPDF/HP_AGILENT/HP__8757A_OM_1.pdf

For an example of a NWA with a "RF Out", see the HP 8753C at http://www.ebay.com/itm/HP-8753C-Network-Analyzer-300-kHz-6-GHz/281062308784?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D777000%26algo%3DABA.MBE%26ao%3D1%26asc%3D27538%26meid%3Dbc1bc0d4ce4b49a5a1333d41ff4fbc54%26pid%3D100009%26prg%3D11353%26rk%3D1%26rkt%3D4%26


texts: Manually placing Rooms in Altium does not create a rooms

texts:
I am currently creating a pcb that will, at some point in future, be placed in a case that is not known yet. Therefore, the final PCB shape/size and connector placement is not determined yet.

I began to route functional groups in themselves, intending to not route the connections to other functional blocks yet, until everything has been set.

In order to move the groups easily, I would like to use rooms. There are options to place rooms via Design - Rooms - different options for room placement. i would like to use this option instead of having the ECO generator generate rooms from my schematics, as im more flexible with their shape if placed manually.

However, placing a room manually does not actually place a room. When starting to place a room, the cursor changes, I can click to e.g. set a polygons points. On finishing the placement, Altium runs through some design rule checks and then ... nothin happened. No Room has been placed. (Same if i select the components and tell Altium to place a room around the selection).

I have used this before. Not sure why its not working now. Maybe there are some options I am not aware of?

SOLVED

yes, it was an option that I was not aware of: Design - Board Layers and Colors - Show / Hide tab - Rooms was set to hidden.


texts:
I am writing Ethernet drivers for an STM32 chip. (The reference manual is available here.) At various points, the concept of "jabber timeout" appears, and is not explained. A quick Google search didn't reveal much more information.

What is a jabber timeout?


texts: Power Supply Orientation Affecting Output

texts:
I am using an NI PS-14 power supply from National Instruments. I just noticed on the data sheet that the orientation can effect the output power and even the life of the product.

You can see the A1 curve drops for each orientation compared to the standard. Why does this matter? What could the orientation possibly be changing that causes this?


texts: Aluminum or Plastic for a board with PCB trace antenna

texts: I have a PCB and am looking to make an enclosure for it. I was wondering if I should go with a plastic box or whether I should go with an Aluminum case. Also for better range does the PCB trace antenna have to be sticking out?


texts: Copy component from Library to another in Altium

texts:
I am creating a new schematic library in Altium Designer and will add different "New Components" on it. Since I already have similar components in another library, so I want to copy some components into the new library and start to edit it instead of redraw it from the begining.

Is it possible !! How to do that in safe way ?


texts: Can I use higher rated capacitor and larger package (for capacitors, resistors, etc?)

texts:
I am trying to design a "custom" design for ESP32 based on the ESP32-pico-kit_v4.1_20180314_en.
Schematic: ESP32-Pico-kit V4.1
BOM:
Why do capacitors C2,C4 and C15 have the same capacitance but different voltage ratings?
Is that for saving some space since the 6.3V is 0402 instead of 0603 and probably being cheaper or it does it have to do with ESR?
Regarding the resistors, could I replace them all with 0603 since 0402 is hard for me to solder?
By replacing them, is there any chance that the different package would make ESP32 not to work properly? If yes, why?
If ESP32 would work properly, are there any other cases where replacing with higher/smaller package would cause something not to work?


texts: dB formula when input and output resistances are equal

texts:
Why is the equation of dB voltage gain independent of the input and output resistances? Also, please consider reading the paragraph. I'm not able to understand this.

Thanks in advance.


texts:
Capacitors are often approximated as infinite conducting plates. I find this approximation surprising since the capacitors I've seen in circuits are only a few centimetres big.

For all the derivations of formulas and laws for capacitors my book assumes an infinitely large plate. Since the conductors I've seen are incredibly small compared to infinite plates shouldn't all laws be invalid since the assumed approximation of its size is completely invalid?


texts: I need to lower a 12v, 100mA signal voltage to a 5v signal voltage of any current rating. Here's the catch: I need that 7V drop to be constant with any input voltage. For example, since it is a signal voltage, if I drop the signal to 10V, it needs to output 3V. Likewise 7V to 0V, etc. what device would accomplish this?


texts: What does it mean if eye diagram voltage (0 and 1 level) goes negative?

texts:
I have created a differential channel and was testing the channel with simple testbench to check the eye diagram. Now I know the channel performance is very bad (It of several PCB transmission lines, Via & Stubs, and Packaging model). But, I am curious while simulating channel performance, I get negative eye density while checking the eye diagram after the channel which is for me unusual. My channel can be very bad as it is not well matched to 100 ohms. But keep those aside, how can an eye density be negative? what does that mean? If the channel is poor, the can be closed more which I know, but this thing is completely new to me. Can you explain why has it happened (Eye density negative) and what does it mean by negative? I know I can improve it with an improved channel.

Note: I have done the simulation in ADS.

Test Bench

Eye Diagram:

Channel S-parameter (Log scale: X-axis)

TDR Differential Impedance:


texts: I want to build my own PIC programmer, can any one point me into right direction. Links, tutorials, books etc would be very helpful ? The programmer should use USB for communicating with the computer but even Serial port communication will also work?


texts: I am wondering what the effects are of putting diodes in parallel or putting them in series. (like current capabilities, voltage capabilities etc.) Let's say I have a datasheet of a diode. What characteristics would change ? My estimation is that putting parallel would increase the current capabilities, but may have a negative effect in reverse leakage. I have no idea if I am right or how to test it, so any info on diodes in parallel or series would be great.


texts:
I'm doing a Layout and I have some problems deleting an internal layer. As you can see in the pictures below I have 4 layers (1, 2, 15, 16). But somehow I also have a layer called Route 3 (3).

I get the error:

  Can't delete internal layers`

as soon as I try to remove the layer in the display window.

How can I remove layer 3?


texts: Does anyone know what connector should I use on the picture below? All I know is it's a power supply connector.


texts:
Sorry for such "noobish" question but I've tried to help my son with learning PIC programming. I load some simple asm source into MPLAB and pressed "make and program device main project". IDE build source and shot it into PIC12F629, program started, LED's were flashing as they should by source... everyone happy.

I'm an old school guy and have no idea about erasing... We tried same routine again and then we discover that we have to erase PIC to do it again?

How? (PICKIT2 programmer)


texts: DC/DC converter with LM25085A and FDC5614P is not converting voltage

texts:
Guys I designed a DC / DC converter from 12V-34V IN to 3.3V-OUT and I used the Power Designer from TI to help me in the designer of this converter in the website simulate everything went well. the output is the same voltage that is coming in. It is not converting the voltage.

The design of my circuit is this one.

The converter I am using is LM25085A with mosfet P-CHANNEL FDC5614P, I did as TI's Power Designer did not occur as I expected.

[UPDATE]: This is the circuit generated by TI Power Design exported to eagleCAD.


texts: Is the use a very small value resistor negligible?

texts:
I made a simple LED circuit for a hobby project. It uses a cellphone charger rated at 5V.
There are 2 LED's rated at 700mA at 2.4 V in series.
The calculated resistance for my current limiting resistor is 0.5 Ohm.
This is a very small value, but is this negligible ?

I did some research on this problem, but it retuned no results..

Thanks in advance !


texts: Problem when using arduino nano as isp and atmega328p-pu

texts:
I am using an Arduino Nano as an ISP programmer. And I want to program my Atmega328p-pu with it. I followed this tutorial: Using Arduino nano as an isp programmer

But I want to use internal 8MHz clock. So I remove the crystal and caps. (In the picture  shown below )

When I use avrdude to program my chip there is a problem:

  device signature = 0x000000 or 0xffffff

Sometimes it responds a wrong signature like 0x0000ff. Can someone help me solve this problem?


texts: Can I replace a board fuse like the one in the picture with a radial one?

texts:
The fuse on one of my commercial printers blew. See picture below. I am planning on replacing it but cannot find an exact fit. The closest I can find is another 400mA / 72v fuse that is labelled as "radial" instead of being the usual ones found in a main board.
This fuse leads directly to the printer's piezoelectric printhead, so it's important. It's a very expensive part to replace (around 1,800 USD for the part + labor).
Here's a link to the closest fuse I can find in terms of mA and voltage:
https://www.digikey.com/en/products/detail/bourns-inc/MF-RX040-72-0/2045641
And here's an apples to apples (in terms of looks) fuse I found that doesn't match the requirements exactly. Its indeed 400mA but only at 50 volts DC.
https://www.digikey.com/en/products/detail/SF-0603F040-2/SF-0603F040-2CT-ND/8747908?itemSeq=354051583
I'm a beginner at this and I really appreciate any help offered.
Alex


texts:
In the process of designing a broadband RF amplifier, I've come across some commercial boards, claiming gain flatnesses of +-1db from DC to 1Ghz. Those boards are ridiculously simple, having only one or two transistors and, in some of them, almost no matching on either side.

See for example this one:

https://www.dhgate.com/product/1mhz-to-2000mhz-64db-gain-nf-1-8-rf-low-noise/425922302.html#ENhp-en

It doesn't have input bias, no matching, no nothing, beside DC power and chokes.

Despite the simplicity, the specs claim 64db of absolute flatness from DC to 1Gz, and they even show a graph of S21 showing it.

How is it possible to archive such impressive performances with those simple circuits?

Are the active devices internally matched and biased?

Or are all those boards nothing but chinese fakery.

Thank you!


texts:
I have a setup where I need to measure the weight at the end of an arm.

The arm is clamped between two pieces of aluminum at one end.
The Sensor S is mounted a short distance (5cm?) from the aluminum base. The distance from the sensor to the end of the arm is 25cm.

The weight at the end of the arm ranges from 1kg to 100 kg. I'd like to measure it with an accuracy of 0.1kg.

How do I calculate what kind of range my sensor should have?

How do I select the best sensor for this application?


texts:
I have noticed that mp3 players around the 32Gb area seem to be fairly expensive; I haven't seen any for less than £150. Conversely, players with smaller storage can be found at a much lower price, for example 4Gb players are usually about £20.

32Gb MicroSD cards can be bought for around £12, so the price of storage does not appear to be the main factor.

If I were a cynic, I might think that companies are artificially inflating the prices of their higher-end models. However, I would like to know if there are any electrical or electronic limitations on creating cheap players with larger storage capacity. Perhaps there are problems with the battery life when using larger storage? Or difficulties with the ability to search the larger memory efficiently? Or is there a difference between MicroSD and the flash memory used in mp3 players?