texts: How does a USB-C to Lighting Adapter work / How to replace them?

texts:
So, I am fairly new here, and to be honest I have no clue if this is the right place to ask.
I am currently thinking about replacing a Lightning port with a USB-C port, just for power supply. At first I thought, if I were to just take a USB-C port and wire everything according to the pinouts, the device should work just fine. But then I realized, that most cables or adapters have a little chip inside. I assume this is for the logic that happens there, e.g. regulating data input and output and power input and output.
I wanted to understand how a USB-C to Lighting adapter really works, as this might help me with replacing them. Unfortunately I could not find any blueprints for the adapter.
I did find some images on how the pinouts of both of these work, would it be sufficient to wire those accordingly? Is this chip I was talking about necessary for a power supply?
Can anyone help me with this? An article about how they are made, a blueprint or pretty much anything.
Thanks in advance

Edit:
My goal is to replace the Lightning port with a USB-C port on the gen 1 airpods charging case. To learn more about this I first wanted to experiment with the connectors etc. As a start I wanted to make a cable going from USB-C to Lighting adapter and charge the Airpod Case this way.


texts: triangle wave form to sine form through band pass filter

texts: Why and how does this active band pass filter change a triangle form to a sine form? I know that the band pass filter consists of a low pass and a high pass , so it cancels out some frequencies , but I don't understand graphically how this could happen.


texts: Am I calculating a pull-down resistor correctly?

texts:
I'm working on a board with a MAX3221. I chose this device because you can disable the DOUT-RS232 output and the RIN-RS232 input which is very important, and critical, for my application.
In order to achieve this, the MAX3221 /FORCEOFF input shall be LOW to disable the DOUT-RS232 output and /EN input shall be HIGH to disable the RIN-RS232 input. I know that the microcontroller I'll use to drive the MAX3221 has pull-up and pull-down resistors on the outputs but:

The GPIO pins are configured as INPUTs on reset (floating).
The Pull-up or Pull-down is not enabled on reset.
I have to configure the pull-up and pull-down I need in software and that doesn't happen instantaneously on boot.

Therefore, I need a hardware solution using external pull-up and pull-down resistors directly on the MAX3221 pins since I need the DOUT-RS232 output and RIN-RS232 input disabled the moment I power up the board.
I have no issues with the pull-up resistor and there is plenty of information about that, but I'm struggling to know how to calculate an appropriate pull-down for the /FORCEOFF input. There are quite a few answers on this exchange but all of them explain where and why to use pull-downs but not how to calculate them.
As a starting point, I know that any reasonably value resistor I put in the input will pull down the pin. The problem I have is what value is the best for when I need to send a "1" to the pin.
Given the three initial conditions on the input pins stated above, I decided to configure the output pins as push-pull which by the way is the default configuration for an output pin. So I have the following circuit for sending a "1" to the /FORCEOFF pin:

I'm trying to calculate the resistor so I only draw 5ma from the pin while maintaining 3v to ensure the MAX3221 sees a "1" in the input pin. The MAX3221 datasheet doesn't contain any input current value for /FORCEOFF and only mentions an input leakage current of 0.05ua TYP to 1ua max so I assume it is negligible for the calculation.
It seems pretty straightforward, but I'm not sure if I'm doing this right.


texts: Issues with combining counters for traffic light

texts:
I am trying to implement something as simple as the controller for one single traffic light by using two counters (one for green/red and one for yellow), but I don't seem to be getting the timing right.

My first counter looked something like

entity counter is
    generic (
        max_count : integer := 50
    );
    port (
        clk : in std_ulogic;
        rst : in std_ulogic;
        count_value : out integer := '0';
        flag : out std_ulogic := '0'
    );
end entity;

architecture behav of counter is
    signal count : natural := 0;
begin
    count_value <= count

    process (rst, clk)
    begin
        if rst = '0' then
            flag <= '0';
            count <= 0;
        elsif rising_edge(clk) then
            count <= (count + 1) mod max_count;
            if count = 0 then
                -- set flag value for one cycle
                flag <= '1';
            else
                flag <= '0';
            end if;
        end if;
    end process;
end architecture behav;

which also sets the flag value when it starts to count.

When I tried to implement the traffic light (simply a state machine) by means of this counter, I got stuck. When I just start the red/green counter c_redgreen once, i.e. the counter is never reset. The problem with this approach is of course that the time where the traffic light is yellow is not taken into account (e.g. the light starts with red and stays in that state for 50 cycles, then it becomes yellow for 5 cycles, but then there are only 45 cycles green, because the counter was not paused during the yellow time etc...). I thought this could be simply worked around by resetting c_redgreen while the light is yellow, but immediately after the reset, the flag is immediately set and therefore I can't use something like if rising_edge(rg_flag) then ..., because the rising edge comes immediately (because the counter sets the flag as it starts).

After these troubles, I thought it would be better to reformulate my counter as follows

...
elsif rising_edge(clk) then
    temp := (count + 1) mod max_count;
    count <= temp
    if temp = 0 then
...

to avoid the flag being set when starting, but when I start the clock (in the testbench) with 0, the first red light does not last 50 cycles, but only 49. Also I am not sure whether it is a good idea for a counter to do nothing until it has reached max_count.

My question is thus how I can combine two counters (with or without start-flag) so that I can make my red/green lights shine for n cycles and my yellow light for m cycles. I hope I have been clear enough. If the code for my traffic light would be necessary, I can add it (I just didn't want to make this question even longer). I also don't necessarily need a traffic light, I just want to have these counters running in parallel in some way. Thanks in advance


texts: Why are two of the wires in my ignition switch showing reversed continuity?

texts:
My motorcycle manual indicates that when the ignition switch is in the ON position, continuity should exist between the red and brown wires (which it does) and also between the black and black/white wire. Both pairs should show infinite resistance in the OFF position. The red and brown wires are working perfectly.
Strangely, however, the black and black/white wire only show continuity when the ignition switch is in the OFF position, and infinite resistance when the switch is ON, which is the reverse of what the manual indicates. Why is this happening?

Bike is a YBR125 custom.


texts:
I am back again on this subject. I found the control to output transfer function (Iout/Vc) of my forward converter (current mode) which is particular as it is without output capacitor. Actually it is more simple as there is only 2 storage elements and the order of the system is less than if there was a capacitor. All of this work have been done  thanks to several documents that I found on the web, and particularly those coming from Christophe Basso and Dr. Middlebrook.
To verify that my tranfer function is correct, I decided to simulate it on LTspice and plot it thanks to python.
The transfer function depends on a lot of parameters. Especially it depends on the "artificial ramp compensation (Sa)" and on the "On slope compensation (Sn)"
Here is the transfer function :
$$H(s) = \frac{K_0}{1+Rout*g_0}*\frac{1}{1+\frac{w_n}{Q}s+\frac{s^2}{w_n}}$$
(If you are interested I can write you Q and wn)
where the K_0 and g_0 are equal to (from Christophe Basso (APEC 2014)) :

It seems that I have a problem for setting correctly the "artificial ramp compensation" and the "On slope compensation" as when I set the Sa term to 0, the bode diagramm from python and Ltspice fits perfectly.
Here is the simulation :

I do not think that my Sn term is wrong. It is simply the di/dt given by the ratio between the voltage across the inductor and the value of the inductance.
My compensation is based on this scheme.

In order to find the coefficient "Sa", I decided to simulate the voltage across Rsense with the compensation and the output contribution and to simulate the same voltage without the compensation. Then I took the derivative of each voltage and substract them for having only the slope of the voltage across Rsense in order to get the "Sa" term (the artificial slope). When I got the term I set it on python, and I was so excited to get the correct result ! And then, The gain at s=0 is not correct and it depends on the Sa/Sn term... (g0)
If you have some ideas to help me it will be a pleasure to see it ;)
From my side Sa = 1528000 A/s (My converter is a big converter ^^)
Have a good night !


texts: Why stationary armature is preferred for commercial use

texts:
While reading a book on electrical machines, I found a point that says that for power generation, a stationary armature is the preferred type.
If in any generator, there must be moving parts, why is the choice of stationary armature preferred.


texts: ADC specs: fpbw - infinite resistor noise?

texts:
I'm trying to compute Johnson resistance noise in a simple resistor circuit. However, since all frequencies contribute equally, I am getting an answer of infinity.

It then dawned upon me that the Arduino ADC probably detect frequencies larger than some cut off given by something called the full power bandwidth. Does anyone know this spec for the Due?


texts:
Can anyone identify this mobile phone?

http://www.adafruit.com/blog/2010/10/29/what-is-that-electronic-thing-from-yemen/

http://www.flickr.com/photos/ladyada/5126516011/

http://www.bunniestudios.com/blog/?p=1351


texts:
On the arduino homepage it says about Communication using the ArduinoMega256

  The Arduino Mega2560 has a number of facilities for communicating with a computer, another Arduino, or other microcontrollers. The ATmega2560 provides four hardware UARTs for TTL (5V) serial communication. An ATmega16U2 (ATmega 8U2 on the revision 1 and revision 2 boards) on the board channels one of these over USB and provides a virtual com port to software on the computer (Windows machines will need a .inf file, but OSX and Linux machines will recognize the board as a COM port automatically. The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the board. The RX and TX LEDs on the board will flash when data is being transmitted via the ATmega8U2/ATmega16U2 chip and USB connection to the computer (but not for serial communication on pins 0 and 1).
  A SoftwareSerial library allows for serial communication on any of the Mega2560's digital pins.
  The ATmega2560 also supports TWI and SPI communication. The Arduino software includes a Wire library to simplify use of the TWI bus; see the documentation for details. For SPI communication, use the SPI library.

So there is a second chip ATmega16U2 on the board which channels RX0/TX0 to a COM port via usb to my computer. So one wire is for receiving and one for sending to the COM port. So any software I write or which as been written for the Arduino talks over this COM port at a certain Baud rate and this is the only way Arduino and a computer can interact via usb. Is this correct?

Consequently, if I want to connect my arduino to a certain software with a known interface I must program a connecting puzzle piece between the COM port and said interface?


texts: Fight inrush current with PTC, good go or not?

texts:
To power an amplifier, I use a lipo battery 3.7v (4000mah) or two 18650 batteries 3.7v (4000mah) in parallel with a DC/DC boost converter that boost the voltage to 24.2 volts. The circuit performs pretty well.

On the load side (output) of the DC/DC converter I use a 25V 4700uF capacitor which introduce a problem, inrush current (when charging) for a second or so when switched on. Not a healthy situation, want to avoid this.

I read allot about inrush current and there seem many options to fight against it but it is not clear to me which is the best one. I hope it can be simple as putting one 'simple' component into the circuit without loosing too much effort. The capacitor is really helpfull, especially at high volume with much bass.

So I came allong the NTC and PTC thermisistors. The NTC does not fit the situation and could be risky when the device is switched off and on again when the NTC is not cooled down, so it doesn't eliminate the inrush current. The disposed heat (wasted energy) is also something I don't like.

The PTC one is the opposite, but how fast is it? Do it really fight inrush current? Because the PTC heats up when there is much current but I suppose it takes some time to heat up (and therefore draw some current) before it enables protection?

Before I decide to buy a bunch of these PTC thermisistors, I like to hear/learn/know some advise of you, professionals.

Questions I have:

Does a PTC avoid inrush current from the start (how accurate)?
Does a PTC influence the performance of the capacitor (or the whole achievements of the PSU)?
The amperage, is this the maximum current the PTC can handle or is this the maximum amount of current it will use?

The next question is, will it help to divide the capacitance into several capacitors with the same amount in parallel to reduce inrush current? Or at least to reduce the time of the inrush current.


texts: Generating PWM from rectified sine wave using 555

texts:
I want to generate a PWM signal from a rectified sinus wave similar to the image below using 555 timer IC.

I have designed the circuit below for this.

I want to get a duty cycle of 80% at the peak of the sine wave, and 0% (5% if not possible) at the zero crossings.

How do I choose R16 and R17 resistor values accordingly? How do I do the calculations?

Note: Period of the sinusoidal is 50 Hz. And period of PWM the is

\$ \tau = (R_{11} + 2R_{12}) C_{11} \ln(2) = (101k\Omega) \times (2.2nF) \times \ln(2) = 154 \mu s \implies \text{f} = 6.49 kHz \$ .


texts: Assembler coding for ARM (Cortex-M0 and M3): is it possible/practical?

texts:
Unfortunately there are no questions on Stack regarding ARM and assembler at all.

My concern -- is time critical devices. Let's take for an example one of my AVR-based device (program compiled with GCC) which should do something up to INT0 interrupt. It working with 8 MHz internal oscillator (125 ns one machine cycle) but it took up to 5 microseconds to react for the interrupt. After the code investigation I came to the conclusion that in the beginning of interrupt service routine processor make a lot of work to save it's state which is almost uncontrollable for high level programming languages (such as C is). If I'd use assembler I could for example throw a pin change in the very beginning and keep the rest of necessary calculations after that. Or I could have much more control over the registers' use and therefore much less time to save those registers.

If I'd go to ARM (which I'm planing to do soon) I will have much faster processor core with much more registers and memory space which looks promising. But will I ever be able to have any control over such time critical processes to obtain for example reaction time within let's say hundred nanosecs'?


texts: How to filter the stepped wave from inverter?

texts:
I have a 1KVA inverter/ups setup at my home, did the installation very recently. Everything works perfectly CFLs,Ceiling fans and stuff. It has stepped sine wave output (when on battery) at a max capacity of 600W. Specs are below.

UPS Specification

Battery: 150ah lead acid tubular battery.

The question I would like to ask: The pedestal fan/air cooler makes humming annoying noise when running on battery mode because of the stepped wave form. (I am located at an urban area and frequent power failure is very common and voltage fluctuation is like sea wave.)

Is there any filter/smoothing device that can be used to at least reduce the noise? any links would be helpful.
One of my friend (an electrician) told me that I can use an electronic regulator(the one used for ceiling fans) to filter the supply to the pedestal fan && cooler and that would do the trick. Is this true? If yes, understandable exaplanation would be helpful.

Thanks


texts:
I'm trying to understand how lithium ion batteries work during discharge, looking at the following batteries https://www.nkon.nl/sk/k/hg2.pdf.
My question is how do you determine the current voltage of the batteries during discharge? Looking at the chart showing cell voltage over discharge capacity, from what I understand it's made by testing the batteries, not from calculating.

Is there any easier way to model it/approximate it?  I'm trying to calculate the power of a motor as the battery discharges, and how much difference that does do the power. I have a varying discharge current from 0-20 A, so ideally I'm trying to find some simpler models for the current voltage depending on discharge current and capacity left.

An example,
If I were to run a 3.5 v motor with a total "consumption" of 3 Ah, and a varying load varying from 0-20 A, would the "safest" way be to put 10 batteries in parallel so the cell voltage always stays above 3.5? Or would you take  the average, 10, and put 3 in parallel?

Is there perhaps any easier way to calculate the power of the motor as the battery discharges?

I also have a question about nominal voltage, from what I understand, the nominal voltage is the average voltage when discharged, in this case 3.6 v. Does this mean that the battery can deliver 3000 mAh with a discharge current of 3 A and a voltage above 3.6 v? Or is it with a current of 0.6 A?
And what do you actually use the nominal voltage for?
Thanks


texts: Can a faulty USB device fry other devices on the same hub?

texts:
Some Googling revealed that a faulty USB device may fry the entire motherboard+processor of a computer if it is not fitted with appropriate fuses (if it is known though, I wonder why they wouldn't!), however I wonder if other devices on the same hub could be fried as well?

Edit after Olin's answer:
I don't mind killing the hub, but I do mind that the PC or the USB devices are at risk. Does that mean that it is risky to have USB devices which are powered from mains because they could theoretically fail and apply mains to the hub, take it out, and in turn apply mains to the other devices' USB receivers? But isn't that theoretically possible as well that a 2.1 sound system fail and apply mains to a 3.5mm jack as well?


texts: DSPs: Can I perform floating point division in a Xilinx DSP48?

texts:
I need to make a implementation of a floating point division using System Generator and I my version of System Generator don´t support the 'divider generator' so I was thinking several options to make the implementation. One is using the Xilinx DSP48 block.
Does anyone knows if is posible to make a division implementation through a DSP48 xilinx block?
Thank you for your help.


texts: Large dynamic range current sense 1uA - 100mA

texts:
I am looking at large dynamic circuits and came across an interesting project by ETH Zurich called the rocket logger - https://rocketlogger.ethz.ch/

I am a little confused by their current sensing principle for which they implement a low and high range current sensing application. Please see this picture of the circuit below - full circuit @ https://gitlab.ethz.ch/tec/public/rocketlogger/blob/master/hardware/pcb/Cape/Cape_v1_1.PDF

What is the point of/what is U303B doing? I tried simulating the circuit to understand but as I expected because there is no feedback it drives to it's negative rail to try to get it's negative input to be at ground, which is connected at it's positive terminal.

In short - what is the purpose of it? and why does the resistor divider coming into it's negative input have a capacitor on it? Any help would be greatly appreciated!


texts:
Can someone please explain me their workflow in solving the following transferfunction.
I have to find the output-voltage Vo over RL, for an input-voltage of Vi.
I'm not used to network analysis, and it's pretty confusing.

As far is got, this is how I tried to solve it:
 - change every component by it's impedance
 - calculate the parallel equivalence impedance Z, of L1 & C1 (Z=L1//C1)
 - serial sommation of Z & L2
 - voltage divider, for the voltage Vo over RL

However, i don't seem to get the correct result


texts:
I have the following circuit in which I expect a 1.1 V voltage (datasheet)across the diode but I am measuring 6.18 V. This voltage is output no matter what way around I have the diode, consistently & I have swapped it out for another which does the same thing.

It's a 1 M resistor.

Why is this happening?


texts: No breakaway points , No imaginary axis crossing points and No angle of departure

texts:
G(s)H(s) = K(s+1)/[s^2(s+2)(s+4)]

According to my calculations there are 4 poles (0,0,-2,-4) and 1 zero (-1) in this system.No of branches
are 3.The centroid is -1.67 and the angles of asymptote are 60 deg. ,180 deg. & 300 deg.But in this case there is not any breakaway points and Intersection points with Imaginary axis and angle of departure.Therefore I'm hard to complete my root locus due lack of knowledge.There is someone who can fill that gap of knowledge I'll highly appreciate.

This is what I have done so far.

enter image description here


texts:
So I've been trying to derive a the network function for a Band-Pass filter. I use voltage division to get a relation for the voltage output across the inductor.

simulate this circuit – Schematic created using CircuitLab

$$
H(\omega)=\frac{V_{out}}{V_{in}}=
\frac{Z_{out}}{Z_{tot}}\\
H(\omega)= \frac{\frac{Z_L Z_C}{Z_C + Z_L}}{R + \frac{Z_L Z_C}{Z_C + Z_L}}\\
$$
where $$
\frac{Z_L Z_C}{Z_C + Z_L} = \frac{-j\omega L}{\omega^2 LC -1}\\
$$
All said and done I'm supposed to get something of the form
$$
H(\omega)=\frac{k}{1+jQ(\frac{\omega}{\omega_o}-\frac{\omega_o}{\omega})}
$$
Where I know
$$
\omega_o = \frac{1}{\sqrt{LC}}
$$
and where I thought my values for k and Q should be
$$
k=\frac{1}{R}\\
Q=\frac{1}{R}\sqrt{\frac{C}{L}}\\
$$
Once the dust settles on my current derivation, I get
$$
k=1\\
Q=R\sqrt{\frac{C}{L}}\\
$$

Now, I'm having trouble simulating my result, so my usual verification method isn't working. I would love to know which of the above (if either) are correct and where I may have gone wrong. Thank you!


texts:
I'm looking at my friend's notes on choosing resistor values for a simple infrared generator circuit. I don't quite understand it and was wondering if you guys could help me.

I understand how they got V(RE2) and V(comp) but I'm not sure what Isink is. Could someone please tell me where on the diagram Isink would be and how they got a value of 6mA for it? I'm not sure if they calculated that value or knew it from a datasheet.

Thanks. :)


texts:
Has anyone ever used the circuit simulation 'EveryCircuit'?  I bought an android license for it back in 2012 and used it quite a bit for simple circuit tests prior to building something as a lay person.  It was a useful way to see a circuit work to better understand it.
I just went back to use it again to try to figure out something on a mosfet switch circuit, but the values they use for adding a mosfet and configuring it are units I can't seem to find on a datasheet anywhere. Things like:

width/length (in micro/nano meters)
VTO, KP and Lambda

They don't seem to have any documentation available anywhere any longer and their forums appear to only be for posting software circuits.

Can anyone point me toward how I obtain these off the values on a datasheet so I can tweek the sim to match the components I have on hand?


texts: Antenna impedance matching within metallic enclosures

texts:
What im trying to achieve is kind of an chip antenna breakout board, since it must sit within a metallic groove.

The plan is a PCB of 10mm diameter with an U.Fl connector on the back and an antenna and a pi matching network on the front.

I also tried to calculate the required trace width with 0.4mm, 1.0mm and 1.6mm PCBs, but first iterations of this design showed a big difference between calculation and measurement with a VNA within the metallic enclosure.

So I'd like to know what best practice would be to choose a matching network or what parts of the design I could change to make this design more viable.


texts: I am creating my own PLC, just for practice with PLCs (as I am an electrical apprentice). I have bought a power supply which changes 240V AC to 24V DC. When it is connected to my PLC unit, and I read the output with my multimeter, the output just pulses, so nothing useful happens. The LEDs on the PLC unit also light up for half a second or so. However, when I disconnect the output leads and measure the output, I have a steady 24V DC output. Any ideas on what the problem is?


texts: Is it possible to pass netlist via command line to ngspice instead of using input file?

texts:
Is there a way to use ngspice command line without providing a circuit file? ex: passing the circuit as a string within the command line ?

EDIT

Currently the only way I could use ngspice in command line is by providing an input file.. I could not find an example of using pipe mode though to pass netlist directly via command line without have to use a file to read from.


texts:
I an trying to run a CCTV 5mp camera from the end of my long driveway to my DVR. Using RG59 18/2 awg 700' 12v dc. I get some voltage drop when IR LEDs turn on at night and makes the camera turn off. I don't have a power source anywhere near the camera so of course I'm having issues.
I also have some video distortion "horizontal scrolling lines".
I was wondering what I can do to make it work.
I'm thinking about running RG6 or RG11 to help with the video  distortion
But what can I do to get power at the right voltage to the camera?


texts:
I'm playing with the TI's DRV8256PEVM evaluation board based upon a DRV8256P driver.
The GUI connects to the board and I can enable the driver and change the IN1/2 PWM duty-cycle.
In the right pane I read AIFS = 0.5A.

I'm not sure what AIFS really means. A Google search with (DRV8256 AIFS) returns NO matches! And AIFS alone shows too much unrelated results.
I guess it is the Itrip, because when I measure a current on my power supply of 2x AIFS the driver rises the fault flag and disable the outputs.
The Itrip is set by the Vref slider (Vref = Itrip * 0.66) so a Vref of 3.3V should set Itrip at 5A. Anyway, changing the Vref slider does nothing about the actual Itrip.
I measured the Vref on the header and it reflects the actual position of the slider.
Am I missing anything?
UPDATE
The datasheet says VrefA and VrefB should be tied together. Instead only VrefA follows the slider, while VrefA is stick to 970 mV.
So I removed R20 and R27 (0 ohm) and tied both Vref to 3.3V.
Surprisingly, the fault condition happens again when the average load on the power supply goes above 1A.
Furthermore, if I keep the current below 1A the motor spins, but the chip becomes so hot in a few seconds.


texts: How to evaluate the reliability of a PCB-printing service?

texts:
I had a talk with a friend the other day who told me that he had many issues with PCB-manufacturers in China (copying his product, long delivery times, bad quality) and that he had to sell his company because of all these issues.

So I wonder: if I want to produce a PCB-board in higher quantities that also require some IP-standards, and needs certification for the european market, how do I know wheter or not the company I'm going to work with is reliable?


texts: 2.4GHz Warmer/Colder game based on signal strength

texts:
I'm currently looking for options to build a 3 piece game for an outdoor activity company based around the warmer/colder game.

Two teams are each issued a receiver, and each team starts around 400
meters apart.
In between the two teams is a transmitter, which is the objective.
The receiver units periodically emit a "ping" sound.
The intervals between each "ping" sound become shorter the closer the receiver gets to the transmitter.
The teams are released in to the play area, which will be a forested area, to hunt for the transmitter.
The first team to reach the transmitter is the winner.
The transmitter/receivers should be able to run for at least 4 hours on a LiPo.

I'm not generally a low-level engineer. I'm quite experienced with Arduino/Netduino/Zigbee/Xbee, but nothing lower level with that really.

My initial idea for this was to use the RSSI output from an XBee on each receiver to measure the signal strength, and parse that with a small Arduino in to whatever output I wanted. The issue with this idea, is it relies on two transmitting XBees, and two Receiving XBees, as well as two Ardunios. Quite an expensive build! (two of each pair so the receivers don't measure the distance to each other!)

I'm pretty certain there is a significantly cheaper way to implement this, as PMR radios (for example) are able to meter signal strength), and you can even get those little WiFi key chains that show signal strength around you.

Would love to know peoples thoughts, or even if somebody has done something like this before a block implementation would be great!


texts:
I have an arduino, beaglebone black, and an arndale octa board and they all work 5V DC (albeit different amp rates).  Most of my electrical sensors seem to operate around the 5V range.

Why is this the case?  How is it I can power a linux computer with 10 watts yet my light bulbs need 60?


texts:
I got a new STM32F0 31 K6 nucleo board and I need to make a GSM UART interface on that board. I need to send an AT and receive an OK from the GSM board as a first step.I am able to transmit AT successfully
But cannot receive anything. I am using IAR.
I am using PA9 - TX and PA10 - RX.
How to create a transmit and receive code using interrupts using this HAL library.
I wrote code using interrupts and it's not giving a single character.
This is my code

     int main(void)
{

  HAL_Init();
  /* Configure the system clock to 48 MHz */
  SystemClock_Config();
    /* Configure LED3 */
  BSP_LED_Init(LED3);
  UART_Init();
  BSP_LED_Off(LED3);
  if(HAL_UART_Transmit(&UartHandle, (uint8_t*)aTxBuffer, TXBUFFERSIZE,100)!= HAL_OK)
  {
    Error_Handler();
  }

    if(HAL_UART_Receive_IT(&UartHandle, (uint8_t *)aRxBuffer,6) != HAL_OK)
  {
    Error_Handler();
  }
   /*##-5- Wait for the end of the transfer ###################################*/
  while (UartReady != SET)
  {
  }
    /* Reset transmission flag */
  UartReady = RESET;
  /*if(HAL_UART_Transmit(&UartHandle, (uint8_t*)aRxBuffer, 6,1000)!= HAL_OK)
  {
    Error_Handler();
  }*/
  while (1)
  {
  }
}

IRQ handler

void USARTx_IRQHandler(void)
{
  HAL_UART_IRQHandler(&UartHandle);
}

Receive callback function

void  HAL_UART_RxCpltCallback(UART_HandleTypeDef *UartHandle)
{
  if(UartHandle->Instance == USARTx)
  {
    /* Set transmission flag: transfer complete */
    UartReady = SET;
    BSP_LED_On(LED3);
  }
}

And when I am debugging the code stuck at this point .

/*##-5- Wait for the end of the transfer ###################################*/
  while (UartReady != SET)
  {
  }

My actual application is to send an SMS to the GSM board using UART and collect the reply in a buffer and then parse it.First i need to make this interface
And I cannot use DMA as there is no idea on how much data is received on this commuunication.

please help guys..

Regards,
olivia


texts: Should I take precautions when using different CAN transceivers on the same bus?

texts:
What are the precautions I should be aware of when using different transceivers on a CAN bus?

What I can think of:

They neeed to operate at the same voltage (on CAN_H and CAN_L)
They need to have some common baudrates (at least one)

Is there anything else?

For example I would like to use both these transceivers on the same CAN bus:

MCP2551
SN65HVD230


texts: LiFePO4 or 'Standard' lithium (Chinese cell) pack for e-moped build

texts:
I am trying to build my own e-moped for university in Hawaii and I am in need of some advise for the right pack. I currently have two orders awaiting payment on alibaba. They are both 48v 50ah and I have requested that each battery can safely pull 70A.
What the suppliers are claiming: Both suppliers claim that my custom battery pack will have a 70A BMS and will safely discharge 70A without damaging the pack. I'm unsure about this claim because that is a lot of power for 48v lithium and LiFePO4 batteries!
Size of each pack (50ah): Lithium: 370x136x170mm Lifepo4: 380×170×105mm
Price (): Lithium: $1150 Lifepo4: $909
What do you guys think I should choose? My bike will bull about 65A constant at max speed.
TIA for helping me out, I greatly appreciate it and whatever decision I make I will be sure to update you guys on how good Alibaba battery packs are :)
Cheers!
EDIT
**I went for a lifepo4 battery. I confirmed all the information above with more suppliers and it seems as though they can produce the battery to spec.
Why did I choose a lifepo4 battery? Well, I went for lifespan (very long compared to 'average' lithium) and the fact that the VOLTAGE SOMEWHAT REMAINS THE SAME for MOST of the discharge cycle. However, the voltage does decrease rather quickly when it does reach a certain point. So, That means great performance for the whole ride with the cost of an inaccurate battery capacity monitor!**


texts: SPST RF switching application with PIN diode

texts:
I need a single-pole single throw (SPST) RF switch. I have implemented the following circuit for 2.4 GHz,

(PIN diodes in RF switch applications / Infineon)

I obtained the following S11 results with a patch antenna:

Which is very good.

However, if I use the same circuit for my monopole antenna, S11 results are the following :

As you can see, the S11 characteristic is not so good as the patch antenna. What should I do for this situation? Why does my SPST circuit work with the patch antenna very well, but cannot perform similar results for the monopole antenna?

Thank you


texts:
Three different B450 motherboards have an output stage supporting 40 amps (6 phase), 50 amps (4 phase), and 60 amps (6 phase).
I would like to understand the relationship between input to VRM (assume +12v DC at 40 amps) to the current limit deliverable to the CPU.
How many amps could be delivered @ 1.4 volts to a CPU?


texts:
I have got a SEPIC converter design see here:
http://www.linear.com/docs/27994
The calculation of the SEPIC converter starts at page 21.
For the input capacitance on page 17 they tell you need:

\$I_{RMS}(C_{IN}) = 0.3 \cdot ∆I_L \$

This is a current and not a capacitance how can I calculate a capacitance value from this current?

On page 24 they calculate the coupling capacitor current:

\$I_{RMS}(C_{DC})\$

but again this is no capacitance. How can I calculate a capacitance from this current?


texts:
Trying to identify a transistor, ON698   6N608 ? GR608 ?
part of ignition coil driver circuit on Motronic 1.0 dme on 80's BMW or Porche

Hard to read ??


texts: The precise reason why DRAM is slower to write than to read?

texts:
I just want to make sure I have my facts straight.

In the olden days when I was a teenager and the Internet was unknown outside of academia, I recall learning (I wasn't taught this per se) that writing to DRAM is slower than reading because it takes time to charge or discharge the capacitors inside each DRAM memory cell.

Is this still the case or was it ever?


texts: How to use IO Buffer with defined location in VHDL?

texts:
I am tring to program the ADF4158 PLL Synthesizer with SPARTAN 6 FPGA using Microboard LX9. I studied VHDL for a semster 4 years earlier, and no practical use after that. So I need some experts suggestion to refresh my knowledge and acheive my goal. Below is the block diagram to explain my goal.

I am planning to use the PC to write the REGISTER values for the ADF4158 to a IO Buffer using a GUI tool as the register settings are very complex. Microblaze is the main controller, that sets a Enable signal HIGH for the SENDER block to copy the REGISTER values to the ADF4158, when the IO buffer write by the PC is over. The ADF4158 have 8 registers each with 32 bits. Below is the block diagram of the SENDER block:

The ADF4158 uses a particular timing sequence to tranfer the values to the 8 Registers. The value for the desired register is identified by the LSB of the 32 bit data of each register bit sequence. The Select Line needs to be toggled after each register data transfer. Image above.

Below is the code I wrote to establish the desired goal:

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity Sender is
Port ( SS : out  STD_LOGIC := 1;
CLK : in  STD_LOGIC;
MOSI : out  STD_LOGIC_VECTOR(31 downto 0);
Enable : in  STD_LOGIC;
Data_IN : in  STD_LOGIC_VECTOR(31 downto 0));
end Sender;

architecture Behavioral of Sender is
variable counter : integer := 0;
variable bitCount : integer := 0;
begin
process(CLK, Enable)
begin
if rising_edge(CLK) and Enable = '1' then
if(bitCount < 320) ---check to avoid 320 bit out of bound
if (counter < 32) ---counter to toggle SS after every 32 bits
SS <= 0;
MOSI <= DataIN(bitCount);
counter <= counter + 1;
bitCount <= bitCount+ 1;
else
SS <= 1;
counter <= 0;
end if;
end if;
end if;
end process;
end Behavioral;

Now my question is, I want the SENDER to read the data from the IO Buffer and send to the ADF4158 device. How to I sent up the connection, or is it possible to code to read a IO Buffer with a defined address? This location of IO buffer is the one where the PC will store data. I am not sure if the code I wrote is correct, so i would warly welcome any suggestions for modification.


texts: Integrating on-off-on-off switch with Raspberry Pi GPIO pins

texts:
Please note: Although this question involves a Raspberry Pi, I believe it an electronics/wiring question at its heart.

I'm new to electricity & electronics and I'm trying to get this simple on-off-on-off switch to work as a pushbutton to my Raspberry Pi 1 Model A.

By default, this switch works as follows:

You press the switch, its "closed" and is considered on, but is routing power through the left pin
You press it again and that makes it open/off
You press it again and that makes it closed/on, but now its routing power to the right pin
You press it again and its off; if you press it again we rinse and repeat this cycle

However I would like to wire the left/right pins together to effectively transform this into a typical on/off switch whereby the behavior is:

You press the button and its closed/on, routing power to the line joining the left and right pins together
You press it again and its open/off; if you press it again we rinse and repeat this cycle

I believe the wiring diagram for this type of setup is:

So to begin with, if that wiring diagram is incorrect, please begin by correcting me!

Assuming its correct, then this is my best attempt to wire it to my pi:

So:

Attach left & right pins on the pushbutton together and then route them to the GPIO input pin
Route the middle pin on the pushbutton the GND on the RPi

Can anyone take a look at this and help nudge me along? Have I joined the left & right pins correctly? Do I need a resistor anywhere (if so how strong and where does it need to go)? Am I wiring the joined left/right pins to the pi correctly? Am I wiring the switch to power & ground correctly? Thanks for any-and-all help!


texts: Configure (upload bitstream) to MAX10 without Altera tools using Linux

texts:
I am currently using the flash-based Altera MAX10 in designed attached to main processor which runs Linux on a custom board (the FPGA itself just implements a few peripherals; the processor running Linux is a normal ARM design).

Up until now, I have been using the standard Altera tools for development (Quartus Prime and USB Blaster as the programming software and hardware tools), but once the product ships, we don't have this option.

Since we would like to design to be field upgradeable, we need to a solution to upload a bitstream to the flash of the MAX10 from Linux (the embedded OS) without a USB Blaster or the Quartus programming tools (since it's an ARM board, we can't run the binaries).

So my questions are:

What software tools can be used for this purpose?  (fpga_manager does not yet seem prime-time, and urjtag does not have much in the way of recent Altera support)
What considerations need to be given to hardware design to enable this functionality?  (For example, can GPIOs be used to bit-bang JTAG - an ideal solution from a cost perspective - or do I need a chip like a an FTDI)

For the purposes of developing a proof-of-concept solution, I have a MAX10 Eval kit and a BeagleBone Black. I can do whatever software and hardware kludges are required.

Partial Solutions

If you know how to do any of the following, I will upvote any of the following in the hope of putting together a complete solution from the individual pieces:

If you have flashed a bitstream to another Altera flash-based FPGA (e.g. MAXII) with non-Altera software+hardware;
If you have flashed a bitstream to a MAX10 using a USB Blaster using non-Altera software; or
If you have flashed a bistream to a MAX10 using non-Altera programming hardware and standard Altera/Quartus programming software.

Updates:

One of the answers suggested a bootloader-style scheme (which is also suggested in this video, but I am using one of the devices that support single configuration only.


texts: Power output of a transformer with many secondary coils, each coil of turn exactly equal to that of primary?

texts:
I am not a full fledged electrical engineer, and I couldn't find it on google, may be because I couldn't think of better combination of keywords.
My question is, if we have a simple transformer with a primary coil of 500 turns and on the secondary side of transformer, we have 10 different independent coils of 500 turns each of exactly same thickness of wire to that of primary coil; and if we input 100 volts, 20 ampere AC into primary coil, will it produce 100 volts, 20 ampere AC into each secondary coil individually, or the voltage among each individual secondary coil will be (100 x 10)/10 and will the current be (20/10)/10 = 0.2 amps?
Another quick question is, will the length of transformer core affect the total magnetic flux, if the transformer core is very long and there's huge distance between single primary and single secondary coil of same turns and thickness, will the induced voltage in secondary be lesser because less flux will reach secondary coil and some flux will be absorbed in the core during travel of long distance?


texts:
I am working on a AK5578 ADC, and the datasheet gives the following example for an input buffer :

I can't figure out the usefulness of the 10 ohm resistor on output of both opamps. Are they for limiting the output current in case of a short circuit ? And in that case, can I replace the NJM5534 by an opamp that can sustain unlimited output short circuit (MC33078) and get rid of these resistors ?


texts: Using 1:1 Transformer for High Side Switching

texts:
I'm working on a 2-sw Forward Converter with isolated input and output. The design is complete on paper, but I still have a problem in my head: High side switching.

The question is, can I drive the high-side switch with a 1:1 gate driver transformer while driving the low-side switch from directly the PWM output of the IC (UC2843 or UC3843)? Is there a limitation or possible problem on this?

I'm asking this, because we have a 1:1 gate driver transformer in our warehouse and we want to use it instead of selecting a 1:1:1 one or a high-side driver IC.


texts: VHDL Overmapping and Time Constaint issues in Xilinx-ISE

texts:
I have an issue with a module I use for rotation of a vector. I have two operations one uses 2 rotLeft modules and the other uses 2 rotRights. Originally I had occupied Slices overmapping issues which led me to combine the modules which helped a lot however now I am having issues with timing constraints in Xilinx, which results in incorrect output when programmed to an FPGA dev board. I've realized the issue is the rotation modules, when commenting out the four rotation modules port map the designs max speed is around 111Mhz and when in use 1.66Mhz, when only 2 are used it is around 44Mhz max which is fine since operating is 25Mhz. Their are 4 rotation modules in use; however, only 2 are needed at a time, depending on if a button is pressed on the board or not. I attempted to turn two off at a time by switching the with/select clause with a process gaurd and a case statement; however, I end up with LUT Overmapped issues (158%, usually 71%).

Does anyone have any advice for dealing with timing constraints and overmapping issues in Xilinx, or a way to improve the below module?

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;

ENTITY rotLeft IS
    PORT (
    din     : IN STD_LOGIC_VECTOR(31 DOWNTO 0);  -- Input to be rotated
    amnt    : IN STD_LOGIC_VECTOR(4 DOWNTO 0);   --Amount to Rotate by
    dout    : OUT STD_LOGIC_VECTOR(31 DOWNTO 0) -- Rotated Input
     );
END rotLeft;

ARCHITECTURE rtl OF rotLeft IS
    SIGNAL rot  : STD_LOGIC_VECTOR(31 DOWNTO 0);
BEGIN
    WITH amnt SELECT -- din <<< amnt
        rot<=
            din(30 DOWNTO 0) & din(31)           WHEN "00001", --01
            din(29 DOWNTO 0) & din(31 DOWNTO 30) WHEN "00010", --02
            din(28 DOWNTO 0) & din(31 DOWNTO 29) WHEN "00011", --03
            din(27 DOWNTO 0) & din(31 DOWNTO 28) WHEN "00100", --04
            din(26 DOWNTO 0) & din(31 DOWNTO 27) WHEN "00101", --05
            din(25 DOWNTO 0) & din(31 DOWNTO 26) WHEN "00110", --06
            din(24 DOWNTO 0) & din(31 DOWNTO 25) WHEN "00111", --07
            din(23 DOWNTO 0) & din(31 DOWNTO 24) WHEN "01000", --08
            din(22 DOWNTO 0) & din(31 DOWNTO 23) WHEN "01001", --09
            din(21 DOWNTO 0) & din(31 DOWNTO 22) WHEN "01010", --10
            din(20 DOWNTO 0) & din(31 DOWNTO 21) WHEN "01011", --11
            din(19 DOWNTO 0) & din(31 DOWNTO 20) WHEN "01100", --12
            din(18 DOWNTO 0) & din(31 DOWNTO 19) WHEN "01101", --13
            din(17 DOWNTO 0) & din(31 DOWNTO 18) WHEN "01110", --14
            din(16 DOWNTO 0) & din(31 DOWNTO 17) WHEN "01111", --15
            din(15 DOWNTO 0) & din(31 DOWNTO 16) WHEN "10000", --16
            din(14 DOWNTO 0) & din(31 DOWNTO 15) WHEN "10001", --17
            din(13 DOWNTO 0) & din(31 DOWNTO 14) WHEN "10010", --18
            din(12 DOWNTO 0) & din(31 DOWNTO 13) WHEN "10011", --19
            din(11 DOWNTO 0) & din(31 DOWNTO 12) WHEN "10100", --20
            din(10 DOWNTO 0) & din(31 DOWNTO 11) WHEN "10101", --21
            din(09 DOWNTO 0) & din(31 DOWNTO 10) WHEN "10110", --22
            din(08 DOWNTO 0) & din(31 DOWNTO 09) WHEN "10111", --23
            din(07 DOWNTO 0) & din(31 DOWNTO 08) WHEN "11000", --24
            din(06 DOWNTO 0) & din(31 DOWNTO 07) WHEN "11001", --25
            din(05 DOWNTO 0) & din(31 DOWNTO 06) WHEN "11010", --26
            din(04 DOWNTO 0) & din(31 DOWNTO 05) WHEN "11011", --27
            din(03 DOWNTO 0) & din(31 DOWNTO 04) WHEN "11100", --28
            din(02 DOWNTO 0) & din(31 DOWNTO 03) WHEN "11101", --29
            din(01 DOWNTO 0) & din(31 DOWNTO 02) WHEN "11110", --30
            din(0)           & din(31 DOWNTO 01) WHEN "11111", --31
            din                                  WHEN OTHERS;

        dout <= rot;
END rtl;

EDIT:
This is the code for the encryption/decryption https://gist.github.com/anonymous/cd91224afa3192cd2cf2


texts:
Assume the input voltage is a sinewave. How does the voltage/current across the resistor R change with variance of inductivity L? If I we assume L -> inf, what kind of waveform would we get at the output?

If we assume L is very high that means the inductive reactance is very high, in return the voltage drop across the resistor should be very low.

This is what I got after simulating with L=100H, R=5Ohms and a Vin=10V*sin(wt) with a frequency of 1kHz. Blue is voltage across inductor, green is voltage across resistor, red is current.

so my initial assumption seems to be correct but what does the diode do in this circuit? The current running through the inductor gets cut off abruptly after half a cycle but the voltage seems to be the same wave form as the input up until a point where it goes to zero and stays there until the diode is forward biased again.

How exactly is anything here smoother? From what I understood, I could have used a capacitor parallel to the resistor to smoothe the output voltage (which is what I expected this circuit to do) so why doesnt this circuit do the same?


texts: Lux meter - Voltage range problem measurment

texts:
I'm about to build a Luxmeter. I want it to give me a respons of 1mV/lux and be able to detect 10.000lux.

Here is part of the solution I'm about to use (4. Luxmeter): http://sales.hamamatsu.com/assets/applications/SSD/si_pd_circuit_kspd1043e07.pdf

The problem comes when I want to record the output signal with my CR1000.
If I use the single ended input on the ADC I'll have the range of 0-5V and accuracy of 1.333mV (this is not good enough and also, we would only be able to "see" up to 5.000lux). But if I use the differential input of -5V to +5V I'll have the full range and accuracy of 0.667mV witch will work.

But for this to work, I'll use the construction example in the attached pdf and then what? A circuit who can give me negative response added to the coupling point above the "Volt meter" in the example circuit.

Could anyone give me an solution of how this could work?


texts:
I have a problem with LPDDR2 clock period cumulative error measurement tERR(11-50per) but shorter length measurement are OK with some margin. I'm looking at some cause or tips to understand or fix this issue.

Here is a qualification test summary:

I've made additional TIE (Time Interval Error, which is cumulative jitter error) measurement on this 333.33MHz LPDDR2 clock signal over a long period of time (10µs):

What I understand from TIE time trend is that on short interval jitter can be OK but on longer period it can fail as we have some quick variation.

Here is the layout of this differential clock (100µm/200µm/100µm; 33 mm long):

FPGA Memory controller clock output is on the left and LPDDR2 is on the right. In the middle the clock goes under a flash memory chip which is only used at startup but is still powered.

My guesses are:

Flash memory change impedance and decrease signal quality due to some crosstalk from radiated power.
The two via on the left that make the pair not differential also decrease signal quality inducing some long term jitter.
Jitter due to memory controller

If you have some clue to understand this issue, it would be really helpful.

Edit 1:

Close-up screenshot of clock signal at LPDDR2 chip. This is a PoP package.

Edit 2:
Clock capture

Edit 3:

Probable reason why there are some big drops in jitter over time. May be related to software running RAM tests.


texts:
My goal is to test some algorithms for sound localization, so I connected two microphones (MAX9814 boards from adafruit) to my soundcard. In the future I want to use four channels.
I wired them like here.
The problem is that while both microphones work individually, when I connect both of them, the signal of each microphone end up in both channels at the same time. Probably this is due to some cross-talk, because I share the same 5V DC supply. Can anyone explain how to do the wiring of two (or four) microphones and avoid this kind of cross-talk?
This is my wiring right now:

GND, +, Gain and Out go to the MAX9814 board, L- and L+ go to the first channel of my sound card (MAYA44 USB+) via a coax cable with chinch connector, and R- and R+ analogously to the second channel.
Edit: The wiring as shown above is ok. Following the advice of the accepted answer I switched to shielded cables to connect to the sound card. Additionally I reduced the length of all other cables as much as possible.


texts: Remove time gaps before chip select disabled on FTDI

texts:
When using FTDI FT2232H in SPI mode, there are relative short time gaps (~2 ms) between positions where clocks are  stopped and chip select is disabled.
But if data transmission have high speed rate, in this case gaps may influence.

Is there some way either remove this time gaps or make it shorter?


texts:
My project looks like it's perfect for the combination of Sainsmart Arduino UNO and the 8-channel 5v Solid State Relay Module.  It's a kinetic artwork with eight, AC-powered light circuits. Three questions:

Are these two boards compatible?  That is, can the UNO's digital outputs interface directly to the Relay Module's inputs?
It looks like the UNO needs a 9v supply and the Relay Module needs a 5V supply. Can these two boards operate correctly with a single DC supply?
By some chance, does the UNO board offer a 5V DC output that could power the Relay Module?


texts: Is absolute electric potential arbitrary?

texts:
Does it all depend on the reference point, for example is there a true ground potential? Is the true ground potential one referenced with infinity?
Thanks


texts:
Found this fuse at work. Normally these fuses have a single wire inside but this one has a little black "resistor"-looking thing on a spring. What is up?

First picture is of a "normal" fuse. The second one is the fuse i found at work. Hard to take pictures sorry.


texts:
I'm about to buy a parallel ADC to connect to an EPROM in a analog-digital circuit. I've found some potential ADCs but am having trouble deciding if the ADC and EPROM are compatible.

A bistable multivibrator provides a sample signal to the ADC, so there needs to be an input pin to allow for this, which I can't identify. While most ADCs seem to do this without the two monostables, the point is to teach the function of these and the production of a digital signal.

The project is to update an undergraduate electronics project, where students build a digital thermometer, a lot of the currently used components are obsolete. The signal from a thermistor is converted by the ADC, which passes 8-bits to the EPROM. The EPROM outputs a temperature to a 7-segment display.

Components such as op-amps and multivibrators are used for teaching basic electronics (differential inputs, +ve to -ve triggering, A_D conversion, what a byte is etc.), so while there are easier options (we'd use an Arduino if we could), the project requires that we carry out the task this way.

Part of the project is evaluating different options, and as this is electrical engineering, it would be interesting to gauge your opinions on what constitutes basic electronics. What is important to teach absolute beginners and can it be done using microcontrollers?

Sorry if I've missed anything out or if the question seems vague. A lot of these concepts are new to me as a Physicist, and so far any components I look into seem impossible to understand. Most of my electronics knowledge is from carrying out this same experiment two years ago.

Specific issues:

So far I've identified 12 essential pins on the ADC. These are:
 - 8 output pins
 - Vin-, Vin+
 - Voltage regulator signal (I think this is
   labelled as Vcc/Vref in the datasheet)
 - Signal from the multivibrators
   (unsure how this pin is labelled in the datasheet)

Is this correct?

Do you think the selected components are suitable for this task?

Datasheets for the two components:

ADC, EPROM


texts: Can I substitute 3A diodes in a plug in power supply for 2A 50V diode?  Should I replace all 4 in the bridge?  It's a 15VDC 1300mA power supply.


texts:
I am in need of your advice on a BMS design. I am designing a circuit which gets powers from battery or USB input (with Power Path management). After searching I found BQ24232 IC (http://www.ti.com/lit/ds/symlink/bq24232.pdf) will work for me.

Here, I need to have an LED to indicate charging complete (Battery Full). The IC has a ~CHG pin which goes to VSS while charging and get high impedance when getting full, according to the datasheet.

As the datasheet is only giving words on using it to indicate charging status,by connecting LED between output and this pin, I would like to know if this will work if I connect LED between this pin and VSS to indicate battery-full status.
I will appreciate every single possible advice from you all.

Edit: In summary, I need to understand what does this mean by "~CHG is high impedance when charging is complete". And how can I make use of this pin for Battery-full indicator LED?

Thank you


texts:
Im' trying to build a big picture of telecommunication and i'm stuck in a topic, related to digital communication. But the problem is that i can't go too deep into the topic because it is imensely huge and due to time constraint, so i'm trying to get an informal and intuitive big-picture ( but as accurate as i can ).
From what i could read, we can think informally that the probability error is dependant solely on two things :

1 - SNR
2 - Our channel codec ( coder-decoder )

If we implement a better channel codec, we need to pay less SNR for the same probability error.

And also from not-to-deep research, i could pin that SNR would be solely dependant on 2 things  :
1 - Signal power at the receiver. This is mainly dependant on our channel characteristics regarding path loss , on the desired bit rate ( which dictates the bandwidth required ) and on the delivered signal power at the transmitter.
2 - Noise power at the receiver. This is mainly dependant on our channel noise resistance ( how prone the channel is to all kinds of internal noises and external noises ), quantization noise, ISI,etc.

My first question :
I - Apart from the perharps informal and vague treatise, is there some major thing i'm missing on the picture  or is there some major thing i have a misconception ?

The second question is :
II - I have read in a text-book that on a digital communication system with A/D step, SNR is directly proportional to the number M of quantization levels :

This makes total sense because by increasing M, we end-up decreasing the quantization noise and hence decreasing the noise power at the output. By decreasing the noise power at the output, we would increase SNR.

But i'm thinking here that whenever we increase M, we are actually increasing the bit-rate ( with M=128, each symbol is worth 5 bits but with M=256 each symbol is worth 6 bits,so for the same symbol rate, we need to increase the bit rate ) , and hence decreasing the signal power at the output ( because of a higher bandwidth required ) and hence decreasing SNR.
So, to me, increasing M would not necessarily increase SNR as my text-book says...
Is my reasoning correct ?

So these are my only two questions.  Thanks a lot in advance.


texts: Help identify the IC manufacturer: is it really possible that these ICs from the 60's just made a comeback (К155ИД1)?

texts:
So we've been manufacturing Nixie Clock kits for the last few years, and for the multiplexers we used 74141 ICs, or their Soviet clones (К155ИД1). The latter were easier to find on ebay and were used more commonly. These chips have a date code like "8910" which I assume to mean year 1989, week 10.

Since this is all NOS (New Old Stock), I've made a 74141 tester to verify incoming batches.

I received the latest batch of chips yesterday and to my surprise about 1/3 of them failed the tests. Then I noticed that these new chips were visibly different: the plastic package is more edgy, there's some sort of manufacturer logo, and their date code is "1814"!

Compared to an old one at the bottom right:

I later verified that the new chips work on actual nixie clocks, but my tester rejects them for some minor reason (probably the new ones are a bit more sensitive to supply voltage, they also seem to be consuming a tad more current).

Questions:

Which manufacturer is this?
Is it really possible that these ICs from the sixties have just made a comeback?

The practical upside of this is that we'd be curious to contact the new manufacturer directly, to cut the ebay middlemen.


texts: Determine the voltage across the 5.0-Ω resistor in the drawing

texts: I have tried to solve this problem but I haven't seen a dc circuit with a battery on the shared portion so I don't know how to include the 2.0 volt battery in the circuit rules. Please help


texts: I would like to ask for some information about the op amp configuration in the attached photo. What is its function? Some kind of comparator I suppose, given the lack of feedback, but I cannot understand the purpose of the divider R7-R8.


texts: How to route a node from one block to another block in Altera Quartus II

texts:
I am new to designing in and coding with with Altera Quartus II version 13 Web edition FPGA software.
I am trying to split my design across serval blocks in order to make it more manageable.

How do I define an output from a gate in one Block/Schematic diagram (a .bdf file) so I can use it as an input on a gate in another Block/Schematic Diagram without making the output from the first diagram go to a pin first. Think of it as wire from one block to the next.

I do not want the output of the first block to be routed to a real pin.

Reading around got me something along "Node" and "Wire"

I am sure it is dead simple.


texts: How can i use an AC brushless motor to charge a battery? If I need to do it with a rectifier then what kind of rectifier should I use?? My motor is 1250kv and another one is 500kv. Can I use an Esc instead of a rectifier?


texts: From David's comment to this answer I understand that it's an undesirable effect in high speed designs. Can someone explain in detail?


texts: What are the extra components in this dimmer for?

texts: This is a four-component-dimmer (R, C, diac, triac) with an extra diode bridge and resistors R2 and R3. What are they for? I've never seen those before. It looks like the resistors are just parallel to R1 + VR1.


texts: Can we use 3.3 to 5 voltage logic level converter to drive a sensor?

texts:
I have a question that can we use 3.3V to 5V voltage logic level converter to drive a sensor which works on 5V as input voltage? Can we supply that 5V as input voltage to sensor or is there any ready-made module which steps up 3.3V voltage to 5V?
Your precious answers will be highly appreciated.


texts:
The 74HC595 and the 4094B shift registers are quite comparable in their functionality. However, under the hood there are many differences in their specifications, e.g. the supply voltage range. I can grasp most of these differences (which I will not mention here and now), but one specification baffles me: The maximum allowable rise rate on the inputs.

The NXP 74HC595 has a maximum rise rate of 139 ns/V (at 4.5V), whereas the NXP HEF4094B has a maximum rise rate of 3.75 μs/V (at 5V) which is around 27 times as much. This is also true for many other ICs of the logic families mentioned.

What are the design parameters of the IC design that influence the maximum rise rate?
How were these parameters chosen in the example given?
And, maybe (I'm not sure if this question is smart), what is the downside of allowing slow rise rates in an IC design?


texts: Auto turn off switch during power outage

texts:
In my area power outages are a daily routine. And power surges, which occur when the electricity comes back, makes it even worse. To avoid damage of the electronic devices we try to unplug them quickly. However, if we are out of the house, this is not possible.

So, I was thinking of some sort of "automatic switch" which disconnects the device from its power source by opening the circuit when there is a power outage, and which requires human action to turn back ON again.

Is there any simple switch or device that can do this task?


texts: The primary selection criteria for choosing FM vs. AM is dynamic range

texts:
The primary reason for selecting FM over AM is the ability of FM to support a greater dynamic range by spreading the information across a wide range of frequencies, and using more 'horizontal information carrying capacity'.

Trying to increase the dynamic range of an AM signal would require impractical levels of power to be used to represent the same information carrying capacity in a 'vertical' or amplitude modulated scenario?

Yay or nay.


texts:
A prenote; I'm not sure if this falls more into electronics or Arduino, but I think Shift Registers are more so electronic and binary related.

I'm using a single SN74HC595N shift register connected to my Arduino Uno. I'm using Arduino's shiftOut function, but when I send a byte, for example, 11111111, Only Output1 and Output7 are active. I also tried a few different ones, such as01010101 and still, the output seemed nothing like what I would expect (Except 00000000 which did as I expected, and turned all the LEDs off). Here is a chart of the connections to the Arduino:

~the output pins are connected to 3mm LED's through resistors; Everything is directly wired, but VCC is demodulated with two 0.1uF, and a 10uF capacitor, that connects to GND to filter any high frequencies and smooth out the input

And my simple code:

int latchPin = 12;
int clockPin = 11;
int dataPin = 13;

void setup(){
    pinMode(latchPin, OUTPUT);
    pinMode(dataPin, OUTPUT);
    pinMode(clockPin, OUTPUT);

    digitalWrite(latchPin, LOW);
    digitalWrite(clockPin, LOW);
    shiftOut(dataPin, clockPin, LSBFIRST, 1111111);
    digitalWrite(latchPin, HIGH);
    digitalWrite(clockPin, HIGH);

}

void loop(){

}

I am brand new to shift registers (and unfamiliar with bytes) so I apologize for any incompetence, and thank you for the help!

EDIT:
Now, when I send 11111111, I get pins 0, 1, 2, 3, and 7 to turn on. I confirmed this with my multimeter, the active pins read 4.85 volts, whereas the deactivated pins read 0 volts.


texts: N-Mosfet Rds Value Question and Use for Bidirectional Logic Coversion Purpose

texts:
I was using BSS138 for Bidirectional logic conversion from 5v to 3.3v.

Rds(on) 3.5ohm at VGS=10v,
Rds(on) 6ohm at VGS=4.5v

I found smaller package with same price SSM3K59CTB and i need small package its values are:

RDS(ON) = 250 mΩ (typ.) (@VGS = 1.8 V, ID = 0.2 A)
RDS(ON) = 210 mΩ (typ.) (@VGS = 2.5 V, ID = 0.5 A)
RDS(ON) = 185 mΩ (typ.) (@VGS = 4.5 V, ID = 1.0 A)
RDS(ON) = 175 mΩ (typ.) (@VGS = 8.0 V, ID = 1.0 A)

Other values are smilar or better like threshold,continuous current,Vds etc.

Can i use this SSM3K59CTB instead of BSS138 since i dont know what is this Rds affecting. I know it is too much for logic conversion but its package is smallest i could found.


texts: Can I use a 4.7uf 50v in place of a 4.7uf 25v?

texts:
I am rebuilding an audio regulator board on an old school video game. Its a donkey Kong junior coin op to be exact.

My question is....will a 4.7uf 50v work in place of a 4.7uf 25v?


texts: Circuit design considerations using N-FET for a High Brightness UV-LED?

texts:
I'm designing a circuit to power a high-brightness UV LED. I'd like to safely drive it as close as possible to maximum irradiance, and I'm having trouble figuring out whether all the components are properly chosen to avoid damaging/stressing anything (especially the LED, which is relatively expensive).

A Raspberry PI will be used to provide the on/off logic. The PI is powered separately, but shares a common ground with the LED power system.

Ideally I'd like the LED to be driven directly by a N-FET, where the gate is hooked up to a raspberry pi GPIO pin:

simulate this circuit – Schematic created using CircuitLab

The first question I have is: am I reading the UV-LED spec (here) correctly?

Forward Voltage: 3.45V
Maximum Current: 1400mA
Electrical Power (Max): 4830mW

The above three make sense, because 3.45V * 1400mA = 4830 mW. Then I see some peculiar items:

LED Output Power: 1500mW (min), 1700mW (Typical)
Test Current for Typical Power: 1400mA

How can the "Typical" LED output power be 1700mW when the test current for "typical" power is 1400mA?

Essentially, I'm not sure whether my resistor value should be calculated based on the 1400mA figure (5V-3.45V / 1400 mA = 1.11 Ohms) or whether I should be deriving a current from the 1700mW figure (1700mW = 3.45V X I; I = 492mA; R = 3.1 Ohms) and then using a larger resistor.

The second question I have is regarding the NFET. The NFET I have is rated for 1.7A and 30V (datasheet here). But the package is scarily tiny (SOT-23) and my gut feeling says I should ask before proceeding. I will be running this at 1.4A which is pretty close to the 1.7 rating. Will it work, and do I actually need to get a tiny heatsink for this NFET? Or is it better to get a beefier NFET?

Other than that, I'm making sure to get a hefty power resistor rated at 1-2 Watts, all wires will be 22 gauge, and all PCB traces will be nice and fat. Any other power-related gotchas I should be aware of? Power source details also listed below.

Thanks so much!

Datasheet for the NFET (1.7A / 30V):
https://www.fairchildsemi.com/datasheets/ND/NDS355AN.pdf

Datasheet for the UV LED:
https://www.thorlabs.com/drawings/ca01256cc12b40f8-35473EF6-5056-0103-7951A15FE4DCB58B/M405D2-SpecSheet.pdf

2A+ Power Board and battery:
https://www.adafruit.com/product/2465
https://www.adafruit.com/products/353


texts: Voltage gated switch issues for audio application (guitar pedal)

texts:
So i'm a newbie, and with the assistance of my A-Level in electronics step brother we're trying to make a tremolo pedal for guitar. The concept is that an opamp (powered by ±9v) is used as a square wave generator, which will open and close a voltage gated switch which in turn disconnects and reconnects the signal (turns it on and off), at a rate determined by the frequency of the square wave. The circuit below is what i've been using so far.

simulate this circuit – Schematic created using CircuitLab

The issue is that every time the signal cuts out as it's supposed to, there's a loud crack which is what I assume is the shorting of the circuit (the guitar signal, due to 'infinite' current going to ground).

I'm hoping someone has a suggestion how I could resolve this, or alternative suggestions for a voltage gated switch that won't be shorting the circuit. I tried putting the mosfet in series with the guitar signal but this didn't work. If there's a simple way of just getting rid of this crack (which could possibly be solved by softening the edges of the square wave generated resulting in a gradual increase/decrease of voltage above/below threshold potential), this would be hugely appreciated!

Many Thanks,
Zach

EDIT: Representation with output scope of the relaxation oscillator seen here (please copy and paste as doesn't display link nicely):
http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+159.55918304990493+60+10+50%0Aa+304+208+400+208+0+9+-9+1000000%0Aw+304+192+304+160+0%0Ar+336+128+384+128+0+100000%0Aw+400+128+400+208+0%0Aw+400+208+400+272+0%0Ar+400+272+304+272+0+100000%0Aw+304+224+304+272+0%0Ar+304+272+240+272+0+100000%0Ag+240+272+240+288+0%0Ac+304+160+240+160+0+0.0000022+0.25657397239391444%0Ag+240+160+240+176+0%0AO+464+208+464+176+0%0A174+304+160+368+128+0+500000+0.005+Resistance%0Aw+384+128+400+128+0%0Af+464+208+512+208+0+1.5+0.02%0Aw+512+224+512+240+0%0Ag+512+240+512+256+0%0Aw+512+192+512+176+0%0AR+512+176+512+144+0+1+450+1.5+0+0+0.5%0Aw+400+208+464+208+0%0Ao+9+64+0+35+0.3125+0.00009765625+0+-1%0Ao+11+64+0+42+0.625+0.00009765625+1+-1%0A


texts: I am planing to use FGH40N60SFD (here's datasheet) IGBT transistor as a switch (to connect / disconnect from battery 12V up to 5A). How should I choose resistor to connect to gate? I will be using 5V Arduino to do it.


texts: How can I overcome the distortion using in this circuit by using same products as we see in picture ? Or we can use 2n700 series, 3906 and 3904 bjts

texts: Or we can use 2n700 series, 3906 and 3904 bjts. My aim is 10W, gain 100-1000 (adjustable), 50hz-20khz amplifier by using this basic components.


texts:
I'm working on a portable PCB using a 3.7V 500mAh LiPo pouch cell. It's designed to be as low powered as possible (under 150uA). I came across the TP4056 however power consumption is too high for it. Then I saw the MCP73831/2 however I'm a bit confused at it's current draw

Does this mean under normal circumstances current draw is 0.1uA to 2uA. I'm a bit confused on it's conditions particularly with regards to Vstop.


texts: Can I clip an antistatic wrist band to an extension cord ground pin plugged into my wall outlet for laptop work?

texts:
I've done some small laptop stuff without the wrist strap, but I might replace a logic board of a MacBook and will be working on it for a long time. I have wrist straps and might as well use one.
I'm real dumb when it comes to grounding stuff, sorry. Will plugging the extension cord into the wall outlet and then clipping to the cord pin ground me?
I read that clipping it to the USB metal in the laptop is not smart, so I'm not clipping it to the inside of my laptop.


texts: What is the difference CMOS and CCD image sensors? In terms of Infrared spectrum

texts:
What is the difference between CMOS and CCD image sensor arrays? i.e working principles.  Please consider in infrared spectrum.

Which one's fabrication is expensive/ or cheap ?
Which one gives higher quality image?
which one is preferred for large focal plane array? (i.e : 1024 x 1024 )

Thank you.


texts:
I'm new to electronics so please bear with me.  I'm trying to work out what kind of battery would be required to use with the following chip:

http://www.nxp.com/products/interface_and_connectivity/nfc_contactless_reader_ics/MFRC52202HN1.html#overview

The chip will be used in a portable device that needs to run for 10 hours and 200 NFC tag scans before the battery needs to be replaced/recharged.  The chip will be set to constantly scan for NFC tags.

I've read that a NFC tag scan would normally use around 15mA but I can't work out how much power a chip like this uses while actively "scanning" for tags and how that translates to battery usage?

Are there any tutorials that would help me get my head around this?


texts: What are the Differences between Analog and Digital Devices?

texts:
Consider a '555 Timer IC', Is it a Analog or Digital Device ?
Or consider a more complex IC as a Microprocessor.
I know the difference between a analog and Digital signal. But what is the difference between Analog and Digital Devices ?


texts: Powering an LED with a 170VDC Full Bridge Rectifier

texts:
I am currently in the process of designing a Tesla Coil and am stuck at the Full Bridge Rectifier and have some reservations about what I propose to do. Currently, the circuit looks like this:

I decided on adding in a 22kOhm bleed resistor for when the unit is turned off, and thought why not add in an LED to show that the circuit is on. The problem I have is when I throw it into a simulator, it shows me that the cathode on every half cycle will see -170V because it is not earth grounded.

So basically I'd like to know if am I wrong in thinking that the cathode will see this -170V and then reverse bias and blow the diode, and if not then will putting an appropriately rated diode in front of it fix the issue?

Thanks!


texts: Can a Raspberry PI be used for high voltage parallel programming?

texts:
I have a Raspberry PI 2, and I know it's possible to use an Raspberry PI for programming an AVR, but I came across something. Apparently if you brick your chip by fiddling with the fuses you need a programmer with "high voltage parallel programming" capabilities, as stated here. The fuses I mention here are not to be mistaken for fuses like the ones you find in your house, the fuses I'm talking about are the ones set by software running on the AVR chip. The link above also states that HVPP can be done with an Arduino.

Does the Raspberry PI have high voltage parallel programming capabilities?


texts: EMI concern about the length of return traces

texts:
I have many IR leds to drive, with MOSFETs and a single constant 60 mA low side current regulator. The leds are PWM at 1 MHz (50% duty cycle), and the farthest leds are 60 cm away from the regulator.
I am not very experienced with EMI, but from what I read:

I need to "round" the PWM signal to avoid high resonant frequencies
I need to keep the loop area as small as possible
I need to keep the return traces to ground as small as possible

It is not a problem to route the return trace of each led just beneath the power traces on the adjacent PCB layer.
My main concern is about the very long return traces (60cm) which are required to reach the low-side current regulator.
At 1 MHz / 60 mA, do you think it would cause EMI issues, should I use multiple current regulators at regular intervals ? Would you have any suggestion to reduce EMI (besides lowering the frequency)
Generally speeking, provided that the topology/layout allows it, what are the benefits of a ground plane for handling return path, over dedicated return traces (in terms of EMI) ?


texts: Additional resistor in feedback loop of bridge audio amplifier

texts:
Here is the bridge configuration of the TDA7294 audio amplifier, from its datasheet:

Everything is clear, despite the 22 kOhm resistor connected between output of "top" amp (pin 14) and inverting input (pin 2) of "bottom" amp. Could someone explain what is the purpose of this resistor? Why it should be here?


texts: Why multiple coils on a ferrite rod antenna?

texts:
I'm trying to build some ferrite rod antennas to test some avalanche rescue technology and I've been looking at the internals of an old BCA Tracker avalanche beacon to figure out how I should go about designing my own.
I have two ferrite rods (from Fair-Rite) that I plan to try out and test separately. I've done some hand calculations using the formulas:

$$F = \frac{1}{2\pi\sqrt{LC}}$$
(from What do I need in order to build and test a ferrite rod antenna for a specific frequency?)

$$L = K \cdot u_0 \cdot u_{rod} \cdot N^2 \cdot (\frac{Ae}{l}) \cdot 10^4$$ (from https://www.fair-rite.com/product/rods-4078377511/)

After picking some arbitrary target values for L and C given F = 457kHz, I have a general idea of how many wraps of the wire it will take to get close to the target frequency. However, after looking at the antennas in the BCA Tracker and poking around with the oscilloscope I'm not entirely sure how to start. Here's a photo of one of the BCA antennas:

Here are my questions:

Why are there three coils and why is the center coil smaller than the outer ones? Why not just one coil centered on the rod?
Is it necessary to tape or insulate the rod with something before wrapping it with wire?
How would you transmit 457kHz from one of these antennas? Is it as simple as applying a voltage to one of these coils?


texts: Interfacing ILI9341 with PIC18Fxx series

texts:
I am new to embedded development, so please bear with me.

I have to interface a TFT display(ILI9341) with PIC18F452, it does not have any controller chip, I want to run a simulation with Proteus before getting the hands dirty with hardware. I am using mikroC PRO for coding PIC controller and trying to use the inbuilt library provided by mikroC for TFT (https://download.mikroe.com/documents/compilers/mikroc/pic/help/tft_library.htm) but I am not able to use the library and the hardware connections at end of the page does not help in how to connect pins to microcontroller.

So I want to ask:

1)Is mikroC good enough for interfacing a touchscreen and taking input from the user or should I use MPLAB-X.

2)How can I connect the pins to PIC controller, I have read the datasheet but I am not able to figure out should I use SPI or 8-bit bus interface and where the pins should be connected.


texts: Capacitor replacement - different uF value

texts:
Nice to see strackexchange has an electrical site too.
I am not familiar with electrical components and this is a kind of "low level hardware" if I can say it this way.

My monitor's matrix stopped working. With an eye shot I see the monitor itself is working, but the matrix didn't turn on.

After some research I found the problem - It has 3 capacitors on the power supply board which are not looking so good.

I have bought 3 capacitors with the same size and voltage - but the uF value is a little different

Broken capacitors: 820uF - 25V - 105.C max temp
New capacitors: 1000uF - 25V -105 .C max temp

I know that this kind of capacitors can be replaced with other capacitors with almost the same uF value (+/- 20%). But in my case they are 3 (not just one).

I am thinking about replacing them, but I have to know:
Is there a chance to make critical damage to the power board due to the capacitor's uF values?
Can u hint me about what can happen?


texts:
I'm trying to experimentally verify my calculations on resonance on a simple series LC circuit.

To prove resonance, I'm measuring the amplitude on the series resistor. When the amplitude is the highest, then resonance has occured.

I'm using WE coil:

And a ceramic capacitor in series.
Measured both elements values by a LCR meter.

By the formula:

We can calculate that the resonance frequency should be around 1.03 MHz.

But in reality, the measurements doesnt add up.

Firstly, on the calculated resonance frequency, there is very little voltage drop on the resistor.
Secondly there are multiple maximums via the 1-100 MHz frequency range:

At 4.6 MHz = 100 mV

At 26 MHz = 80 mV

At 70 MHz = 100 mV

I'm guessing that at the 26 and 70 MHz peaks, the parasitics kicked in, but what got me more confused is that when I remove the capacitor, the voltage maximums remain at the same frequencies.
Worth noting that the 4.6 MHz peak corresponds to self resonant frequency of the coil by the datasheet.
What is the reason for this behaviour?


texts: checking for 'dirty' power on a power supply using only a multimeter?

texts:
this is a follow up from https://superuser.com/a/958165/43268

It was suggested that i check a 19VDC power supply for "dirty" voltage. If i had a oscilloscope i could probably follow the excellently documented steps from http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html

but all i have is a multimeter. it is a decent one. a fluke 87V. It does not have data logging but does have a "fast mode" that works on a little bar graph and it has hold max/min.

is it possible to check the power supply with just that? would a dirty power supply show up how if all i can measure is the output voltage while under load? would the voltage fluctuate? how much fluctuation should i watch out for?


texts: Step-down Regulator Voltage Drop / Frying

texts:
I'm trying to implement an Exar XRP7659 on a breadboard to step 17V to 5V @ 1.5A. The regulator is rated for 18v. Now, I have the circuit wired up and initially the output voltage is 5V on the regulator but after I add load (a phone to charge via USB) the voltage drops to 3.25V and then spikes to ~16V (presumably fried because it won't step to 5V anymore). I even had one regulator catch on fire! As far as my components, all resistors are 1% except for the 100k EN resistor. The capacitors are all ceramic as well.

Here's the regulators application guide for 5V:

Here's my breadboard's layout with labels:

Any idea what I'm doing to destroy these regulators?

Thanks!


texts: STM32F4 Discovery Board timers, PWM and LEDs

texts:
I'm working on a project where I need the on-board LEDs to respond to PWM from the timers in order to make the LED pulsate over a given time period. I've been able to get the LED to pulsate (blue LED - LD6 mapped to PD15) however I'm having problems controlling the time of the pulse. I also have limited experience with this topic and all the code I've so far compiled has been through guess-work, online-examples and my limited understanding of the documentation.

My timer configurations for TIM1 and TIM4 are as follows:

TIM1

Clock Source: Internal Clock
Prescaler: 1600
Counter Period: 500
NVIC: TIM1 update interrupt and TIM10 global interrupt

TIM4

Clock source: Internal Clock
Channel 4: PWM Generation No Output
Prescaler: 8
Counter Period: 100
NVIC: TIM4 global interrupt

My understanding is that I've configured TIM1 to interrupt at 20 Hz or every 50 ms (I use this to change the PWM value) and TIM4 is configured to send PWM values to the LED at 20 kHz.

My code to change the PWM value is located in 'stm32f4xx_it.c':

/* USER CODE BEGIN TIM1_UP_TIM10_IRQn 0 */
  if (eDir == UP)
  {
      if(ui8TimPulse >= PWM_MAX)
      {
        eDir = DOWN;
      }
      else
      {
        ui8TimPulse += PWM_MIN_CHANGE;
      }
  }
  else
  {
    if (ui8TimPulse <= PWM_MIN)
    {
      eDir = UP;
    }
    else
    {
      ui8TimPulse -= PWM_MIN_CHANGE;
    }
  }
/* USER CODE END TIM1_UP_TIM10_IRQn 0 */

I've defined the constants in main.h as:

  #define PWM_MIN 4
  #define PWM_MAX 100
  #define PWM_MIN_CHANGE 1

I also have code in TIM4 (stm32f4xx_it.c) to control the cycles (I think):

TIM4->CCR4 = (htim4.Init.Period * ui8TimPulse) / 100u;

My problem is that all the pulses seem to only last 1 second and they only seem to pulse towards a state of maximum brightness before seemingly dropping back to an OFF state and starting again. I've tried changing the constants (what I'm showing are the default values although I've played with them extensively) but nothing seems to stretch the time of the pulse out.

To achieve this, should I be working in my code to change the PWM_MAX value? or the TIM4->CCR4 equation? Or should this be configured in the timer configurations? Any feedback on this would be much appreciated.


texts: Master-Slave Amp clipping/saturating problems

texts:
Building a master-slave amp to drive a piezoelectric driver for a sonoluminescence experiment.  Having a problem with the amplification.

The rails are at +/- 45 V (sorted that problem out, thanks to all who helped).  Straightforward design from the data sheet of the OPA445 (45 V) op amp, with capacitive stabilization added in.

The chip: http://www.ti.com/lit/ds/symlink/opa445.pdf

And the actual circuit I'm using. The buffer is necessary because the cheap frequency source will feed back if the input impedance isn't very high.  All op-amps have trimmer pots attached per the data sheet's instructions, and have been properly nulled.

Circuit is driven around 25 kHz, don't think that is a problem for this chip and circuit - it's designed to drive piezos around those frequencies.  At low outputs, it seems to work fine.  But once the output voltage between the master and the slave goes to about 70 V peak to peak, increasing the input doesn't increase the output, it just clips at the top of the waveform.  I can take some pics of the o-scope output if that would help.  As far as I can tell, the output is symmetric to ground (until the clipping starts.)

Any help or info appreciated, will answer any questions I can, but will be on the road over the weekend.  Thanks in advance.

Martin


texts: I'm sort of new to Altium, so any kind of detailed help would be very welcome... I need to create a PCB in altium that has copper all around with small plastic channels surrounding the tracks. Is it possible to create such thing (as described in the picture)? Do I have to create some sort of polygon around it?


texts:
I'm trying to understand what would happen when connecting two grounds from diffident power supplies together.  A more in depth explanation of what I'm trying to accomplish is here: Connect Arduino to existing circuit with seperate power supply

One power supply is 12V and I don't know if it's floating or not in relation to earth ground.  The second power supply will be 5V floating.  If there's a voltage potential between the two grounds and I connect them together will there be current flow between the two grounds or will the floating 5V supply "adjust" itself to the 12V supply's ground potential?

From my understating I thought that when connecting two spots that have a different voltage potential you will get current flow between these two spots.  However I'm not sure if the whole floating voltage situation changes this.


texts: What determines the real world transformer ratio of a clamp on AC power meter?

texts:
The ideal step-up transformer, when the primary coil has 1 winding and the secondary coil has 60 windings would step up the voltage 60 times.

With this improvised clamp on AC power meter, which is essentially a transformer, they used 60 windings for the secondary coil, and the live wire is essentially wound once (or half?). I would expect that to step up the voltage 60 times, but instead they only get 0.2 mV - 2 mV AC of output per 1 amp of current of mains flowing through, depending on the core (various cores used were an aluminum carabiner, a zinc/steel key clamp, a key ring). Why is this so low, does the core make such a big difference that what should be a step up of 60 is instead a step down of 100,000? And why is it proportional to the current flowing?

Edit: A couple clarifications: in this setup the primary is getting residential mains voltage, so 120v. A space heater (1kw, so several amps) is turned on, and the transformer is clamped on to one wire (a split extension cord).


texts:
Can one place large packages (QFP-100) on top and bottom side of (same) PCB?

Of course I could hand-solder them but since I also have some small QFN packages I suspect will need to use reflow soldering, in which case I'm afraid the larger packages will fall off the board or at least will have trouble aligning property.


texts: Low voltage cut out switching for a 6v input SLA to 5v output circuitry - or alternative ideas

texts:
I am currently modifying a wireless video door phone system with remote door release system, for use with a walking frame, for my elderly mother in-law, who lives alone. The 7"monitor runs a 5v 1a DC plug pack normally, but I have used a 6v SLA battery and dropped the voltage to suit. (which works great) The problem lies when the battery voltage gets low around 6v, the voltage dropping circuit components reach very high temps while the unit is powered to normal use. (burning the components, causing smoke and blistering!) I have also setup a bi color LED to turn red at 6.1v, but is difficult to see and I can't seem to power a micro relay from it.

I was considering a low voltage cutout switching module, but 6v modules seems hard to get or to build with my limited knowledge (kits are one thing, designing and building from scratch is out of my league). Ideas are appreciated. 12v has been considered and is probably my next logical step, as 12v systems seem more available, but efficiency seems to go down and battery weight goes up (to use the same ah capacity). System  use is 1A @ 5v DC, standby 300 ma. current battery size 6V 12AH (8 lasts a day) charge rate once a day (over night)


texts: half bridge smps with synchronous rectification basic working principle

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I am trying to understand the basic working principles of a Half Bridge SMPS with synchronous rectification. Whilst I understand the workings of a Half Bridge SMPS with diode rectification, I fail to understand/relate it to the diode rectifier version.

My understanding is that the diode rectifier version works as per the images below; when T1 is on, D1 is forward biased, and viceversa for T2.

However I cannot see it intuitively for the synchronous rectifier version:

I presumed the FETs would directly replace the diodes, however they are connected to ground unlike the diodes, which is one of the reasons to my confusion. I would greatly appreciate it if anyone could shed some light on this! Furthermore, if anyone has some decent literature on this topology please let me know, as I havnt seemed to find much regarding a half bridge with synchronous recification.

Kind regards

Miccio


texts: Proof: A strictly bandlimited signal must also be a signal of infinite time duration

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How can I show that a bandlimited signal is also of infinite time duration?

I know it has to do with Fourier transforms and convolution but I'm not sure how to actually prove it. I also know that the Fourier transform of a rect function is a sinc function.


texts: Trigger 2 triacs in parallel simultaneously

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I am using a STM TPDV1240RG triac to control an AC load. This triac is rated for 40A. The current in my circuit is up to 80A so I was thinking of putting 2 triacs in parallel to share the load.

I am using a MOC3063 with DC pulse to turn on and off the triacs. The problem is that only one of the triacs is conducting (whichever is first to turn on). Is it possible to get them both to fire simultaneously?

Note: I will also be using heatsinks on each or perhaps one
between the two if suitable.

Thanks.


texts: Dynamic switching of radio: Change between wireless protocols in the 2.4GHz

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I want a radio core (transceiver). I want it to work on both the protocols.

  802.15.4 and 802.11

I already know of some SoC which has both the PHY layers to work that up. http://www.gainspan.com/docs2/GS2000-PB.pdf

Is it possible to switch between them in someway with a single transceiver?
I'm thinking of a low energy application with WiFi used rarely and communication done using 802.15.4 (probably 6LoWPAN)


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I would like to use the builtin USB DFU bootloader of STM32F107 chip. My MCU is powered by the device, I don't need to use 5V from the USB.

So far I have connected pins PA11, PA12 and GND directly to a USB cable, but the computer does nothing when I attach the device (I have the BOOT0 pin tied to 3V3).

When I was studying STM32 bootloader details, I noticed that the bootloader also uses OTG_FS_VBUS pin PA9 - probably to detect connection of USB cable.
On the other hand, another guy here uses pin PA10 to do the same thing. Now I am a bit confused.

What pins should I connect to be able to use USB DFU bootloader? Also sometimes there is a pull-up resistor at DP line in schematics from the internet. Is it necessary?

Thank you for your suggestions, have a nice time :)
Klasyc


texts: Reuse a S25FL256S SPI 32MB flash module even when it is possibility protected?

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This is my weekend toy, a Spansion/Cypress fl256saif00 (S25FL256S), a 32MB SPI module. This chip is salvaged from a Cisco EPC3928 Docsis 3.0 Modem Router (2012).

The (first) challenge was to be able to remove it from the donor PCB without damage it and to solder it on a breakout board, just for practice. This seems to be successful so far, nice result. Pretty good for just a first-timer. Because of this result, I just thinking of reusing it with use of a MCU.

I have downloaded the datasheet (it is huge!) and also found a library to create a filesystem on it. However, there are some questions, because this chip is not new and there are several memory protection methods described in the datasheet. I cannot figure out whether it is temporary (active when used inside application) or permanent (forever). For example write protection on some memory areas. I will spend some time on it and want to know for sure, that is not unusable by protection (thus a waste of time), for example impossible to reformat and write data/files to it. It must be fun, no frustration ;-)

So my question/doubts (before I start this investigation/journey) are:

Is it possible when it is protected to unlock the protection by reformat/clear the whole flash memory? Can I reuse it anyway?
In the datasheet, there are several packages, except mine (see picture above). There is a 16-lead SOIC displayed that match the pins however not the size (width), is this actually the same?

Datasheet references:

The datasheets, there are two versions of the same, one branded Spansion and one branded Cypress. I have read that Cypress bought Spansion in 2015, that's the reason there are two brandnames involved. I think I must use the first one, since the IC is labeled with the brand "Spansion" and module is of a device of 2012.

Datasheet PDF: Spansion version
Datasheet PDF: Cypress version


texts: What hole size for test probe to get a snug fit?

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I’m designing a bed of nails test jig. I want my test probes to fit snugly in the circuit board, but want to allow for variation in the through hole plating of the hole.

In Altium, when you specify a hole size, is that the drill hole diameter the hole size after or before through hole plating? i.e. does the PCB manufacturer make an allowance for the plating and actually drill a slightly larger hole?

I am going to use the RC50-SC and RC100-SC receptacles to hold my test probes. What would be an appropriate hole size to specify in Altium in order to get a snug fit?

http://www.farnell.com/datasheets/1680275.pdf

http://www.farnell.com/datasheets/1662754.pdf

Cheers
Phil


texts: Choosing the bias components of a cascode amplifier

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For a two transistor cascode amplifier, how does one determine the base bias resistor ratios? In the design case of a single transistor common emitter, one can use tricks like Ve = Vcc/10 for, from that assuming Vbe ~=0.7V, Vb = Vcc/10+0.7.

Further assuming the base current through the base bias resistors should generally be 10x more than the required base current for the transistor, one can calculate the two base resistors as Rbb (base resistor at the bottom of the potential divider) = Vb/(Ic*10/Beta), Rbt (base resistor at the top of the potential divider) = (Vcc-Vb)(Ic*10/Beta). The collector resistor value can then be calculated roughly as: Vc = (Vcc+Vcc/10+Vce[sat]))/2, Rc = (Vcc-Vc)/Ic.

What rules of thumb and bias calculations can be used for a two transistor cascode amplifier?


texts: I fried my Fluke DMM while measuring voltage across a BBQ Piezo spark igniter. How to fix?

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I was trying to figure out how I broke my Fluke (and more importantly, how to fix it). I had a grill spark generator (such as pictured below). It wasn't working correctly, so I was measuring (I think) the Voltage across the leads. I had the leads measuring it for a few seconds (at least 15 "sparks"). At some point, the DMM went dead, and it won't turn back on. When I remove and replace the battery, some of the LCD segments flash for a fraction of a second and then go dead. It doesn't do anything useful any longer.
Any ideas where to start with troubleshooting?