texts: Using the AC97 Codec on an Atlys Spartan 6 Board

texts:
I'm a beginner to FPGA programming. I just started programming an Atlys Spartan 6 board and so far have written one program to blink LEDs in a counter pattern.

Now I'm trying to send the clock signal down-sampled to audio frequencies to the AC97 codec. Here is the Verilog program I've written:

module music(
    input clk,
    output ac97_sdo
    );
reg [25:0] count_aud;
reg clk_aud;

assign ac97_sdo = clk_aud;

/* down-sample the 100MHz system clock to 1kHz */
always @(posedge clk)
begin
    count_aud <= count_aud + 1;
    if (50000 == count_aud)
    begin
        clk_aud <= !clk_aud;
        count_aud <= 0;
    end
end

endmodule

The bit-file generation is fine, but the code doesn't seem to work - I don't hear anything either on Line Out or on HP Out (I don't know how to control the output, either), and I don't have enough experience with the AC97 specification to figure this out. The audio part of the UCF is:

NET ac97_bitclk LOC = L13;
NET ac97_sdi LOC = T18;
NET ac97_sdo LOC = N16;
NET ac97_sync LOC = U17;
NET ac97_reset LOC = T17;

Do I need to use the bit clock, sync, reset, etc. to make this work? If yes, how can I go about it?

I couldn't find any detailed information on the Atlys Reference Manual.

Please help!

Thank you.


texts: Difference of the following two Fully Differential Amplifier

texts:
I have found two Fully Differential Amplifiers from Texas Instruments. They have very similar names which are THS4531 and THS4531A respectively. I have checked both datasheets and found nothing different. Could anyone tell me why a capital "A" is added? I am not quite familiar with the naming system of TI.

Datasheet links:

THS4531: http://www.ti.com/lit/ds/symlink/ths4531.pdf

THS4531A: http://www.ti.com/lit/ds/symlink/ths4531a.pdf

Many thanks!


texts: How to connect multiple power rail wires together?

texts:
I'm working on a project that uses a 12 V supply, tower light, buck converter & Raspberry Pi.

I am prototyping it on a breadboard, but want a permanent home for it in an enclosure.

What would be a good way to connect all the positive rail wires together & all the ground rail wires together?

I tried using the Wago splicing connectors, but they seem more suited for "electrical" circuitry rather than the finer electronic circuitry.

Is there a best practice for connecting multiple rail wires together between boards?


texts: What is the name of this connector? (4-pin with a vertical line)

texts: I am trying to identify the name of this connector I searched the digikey photos and couldn't find a match one.


texts: Determining Voltage gain in a BJT amplifier

texts:
I've been trying to solve the ac small signal analysis of this BJT amplifier for a while.

The question asks for the following:

Q.4: For the BJT circuit (Figure 4), the signal source generates ac signal with zero DC. The
transistor has \$\beta\$ =100, and ro =20 k ohms.

(a) Find RE to establish a DC current of IE= 0.5 mA. Assume VBE=0.7 V for conduction.

(b) Find RC to obtain VC = 5 V.

(c) Determine the system voltage gain with RL = 10 k ohms.

I was able to solve part a and b. I obtained RE = 28.85 kohms and RC = 20.2 kohms. But, I can't seem to solve part c. I used the t-model to try to solve for the gain. I considered Re to be just internal resistance of the amplifier. That is, re= \$ \frac{V_t}{I_e} \$ and I disregarded the previously found value for RE in part a (because of the bypass capacitor in parallel to Re). I eventually got to the answer \$ A_v \$= -99.2 v/v but the answer given by my teacher was \$ A_v \$=-66.26 v/v.

I've been trying for a couple of hours ( :( ) but I can't seem to be able to solve it. Any ideas?


texts: Significance of Negative reference voltage in DAC0808 Chip

texts: In DAC0808, positive reference voltage is used to set the maximum output current through that chip and the value of the output current can be changed by appropriately setting the bits. Normally, in that configuration we ground the Negative reference voltage pins. So, as it's name indicate negative and reference, is it used to set the current in the output pin? what's the significance of it in DAC0808. I searched in the datasheet but couldnt get enough information, only a diagram regarding it's use is provided.


texts: I2C Code Composer Studio example for MSP430G2553

texts:
I've been scouring the forums for a complete I2C implementation for MSP430G2553 using Code Composer Studio.  All I can find are code snippets out of context or single byte examples.

I need to figure out how to do the following using Code Composer Studio 7x On an MSP430G2553 with I2C:

Write a byte of data to a specific register.
I need to do the above on 2 different I2C slaves.
I need to read MULTIPLE bytes from a single I2C slave.

I am new to controller programming.  I have been programming in Windows for 20 years, but the low level controller programming is just one huge paradigm shift for me.  If somebody could point me to a good example of the above 3 operations that will work in Code Composer Studio 7.x, I'd be very grateful.

I'm not asking somebody to write my code.  I'm just having trouble with the basic concepts of how things work when programming controllers in CCS.  I'm used to calling a function like:

SetPinMode(14,OUTPUT);

The above, when called would set pin 14 as an output pin.

However, when I see something in a TI example like:

UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC;   // I2C Master, synchronous mode

I can't make any sense of it.  It's all abbreviated.  Setting values is acting like calling a function.  It's nice and compact, but for a guy used to calling a function with a meaningful name, it's incomprehensible...  Looks like jibberish.  I cannot read that code and make out what parts of it are doing what..  I'm thinking I might just need some 'Intro to Controller Programming' class to put me in the mode to decipher the above code.

It appears to me that the world of controller programming uses 'short-hand' instead of calling functions.  I'm sure there's good reasons for this, but it's really hard to follow when first starting out.  Any useful help with some explanations that would be useful to somebody like me who doesn't already know the answer would be greatly appreciated.

Anybody can say that they know how to do something.  A truly gifted person can actually teach it to somebody that doesn't already know.  That's what I'm asking for here.  Or at least guide me to some source where the examples ARE spoon fed to start with.  I just don't get the whole paradigm at this point, so it's hard for me to decipher...


texts: Is HP 6623A Linear or Switching power supply?

texts:
I have an HP 6623A  DC power supply and i wonder if its Linear or Switching power supply.
I see in the manual it says linear, but i still wonder.
Why i am asking:
I am asking this, becouse after probing my circuit, i noticed noise of 5MHz (680mV peak to peak) when current is drawn from this power supply, and also the amplitide of the noise increased as i increased the output voltage of the supply.
Using another power supply which is linear on the same configuration did not produce that noise (i only get 20mV peak-to-peak).
Here a picture of my oscilloscope with that noise:

And yes, i probed my circuit the right way:

EDIT:
Added schematic.
Also, the supply says Calibration done: 8-Jan-2010, and the next is due to 2011.
So it is at least 10 years old, and not calibrated.

simulate this circuit – Schematic created using CircuitLab


texts: How to calculate average voltage from a series of discrete points

texts:
I require the method to calculate average voltage from a series of discrete points from an AC waveform.

Everywhere I look the answer is Vavg = Vpk * 0.637. I understand that this works for a perfect sinusoidal waveform but my data wont be perfect and I need the actual average voltage.

Could I just convert all my points to their absolute value and calculate the mean of them?


texts: Analog STDP switch using tactile button with state control

texts:
I'm trying to implement a circuit that consist of 16 similar modules. Each module is a processed signal line which has to be routed into one of two outputs. Shure the SPDT is simple and rugged solution but I'd like to use tactile switch to choose which output the signal goes. And the switch has to remember its state after the circuit is off the power. Is there any way to implement this using DIP or SIP ICs? Thanks!
Please, don't blame me hard form my bad English )))


texts: RFID system to detect a specific object 50 cm away

texts:
I am prototyping an RFID system that can detect a specific object about 50cm away. I've tinkered with the idea of proximity sensors but the issue there is the inability to strictly trigger when a specific object is detected. I started reading about RFID tags and figured that could be my solution. I've seen DIYs of tags in animal collars so that pet doors are opened when the collar is detected, and my system is something similar. The main difference would be the range. The object would essentially have the tag. I need my reader to be about 50cm away, and technically the signal can't be linear since the object can be in different locations within that 50cm radius. Also, the tag should be thin, not bulky so I would prefer avoiding an active tag unless I don't have a choice.

As much as possible, I'm trying to keep the reader compact, preferably can fit in a 2x4 inch enclosure that is also only about an inch thick.

Any suggestions?

Thank you.


texts: Why is Multisim Oscilloscope ALWAYS doubling my input voltage?

texts:
My Multisim Oscilloscope is ALWAYS doubling my input voltage.
If I put a 5Vp in from the function generator, it will show a sine wave with a 10Vp in the scope.
This is extremely frustrating and I would appreciate any help. Here is a screenshot:

Figure 1: This is the scope showing 5V/div - you can see it reaching two division, i.e. 10Vp


texts:
I got a old desktop SMPS rated 250watts. In the output panel its written as, it can supply  a output of 12v16amp. So my question is, it is possible to supply a steady 12v3amps from a 12v16amp smps. I also checked connecting my motor with the smps but the motor rotated for just 2 seconds and turned off automatically.

Thanks!


texts: Is this just "Circuit Wizard" weirdness, OR Another something?

texts:
I was thinking "Circuit Wizard" is a good simulator for learning electronics and analyzing circuits, but this weird thing was seen on the picture.

How can voltage measurement be different on the same wire?

It must be only ZERO for all measurements on the same wire, am I wrong?

It looks like the problem's beginning point is battery voltage drop...

But why....still I don't know...


texts: PIC24 Internal Oscillator and Instruction cycles

texts:
I have some relative experience on AVR but just minimum with PICs. In order to start a project I've  just wanted to verify that I was able to get the internal oscillator working at the right frequency. So,  my first test was to toggle a  pin and see the frequency I've got. The first test code was

#include <p24F16KA102.h>

_FOSCSEL(FNOSC_FRCDIV  & FNOSC_PRI );
_FOSC( POSCMOD_HS  );

int main(void)
{
    AD1PCFG = 0xffff;   //make ADC pins all digital
    TRISA = 0;          //Make all PORTAs all outputs

    while (1)
    {
        LATAbits.LATA6= ~LATAbits.LATA6;
    }
    return 0;
}

The frequency measured on the RA6 is about 59 KHZ. This looked crazy out of a 8MHZ clock. It seems to be that  LATAbits and the negation requires 14 Instructions !!

So I've searched on the internet in order to minimize the instructions to just toggle a pin and found out a built in assembly of BTG so I've repeated the above code replacing the LATAbits with
__builtin_btg(&LATA, 6);

Now the dissasembly shows there are 3 instruction to execute the loop and the toggling

029A  202C40     mov.w #0x2c4,0x0000
029C  A26010     btg [0x0000],#6
029E  37FFFD     bra 0x00029a

Now the frequency at PIN RA6 is 201 KHZ  !!!

What am I  doing wrong here ??? I've tried the configuration bits from the MPLAB without the code etc etc . Is this OK ?  an 8MHZ clock will produce 201KHZ as the best option to toggle a PIN?

It is very likely I am doing something wrong hence why I decided to post this here after spending more than 6 hours trying.

From datasheets I know that each instruction requires 4 clock cycles but I am not sure on instruction cycles, clock cycles and execution cycles. I will appreciate any help or guidance. Perhaps I am more used to 8 bits where the ratio to clock cycles is smaller.  What is the easiest and safe way to verify the clock frequency?

OK Thanks everyone for all the answers as all of them gave me a direction to follow. I have just tested the suggestions from Olin and Madmanguruman. As I did not find a direct way to put inline asm having address tags like loop: below, I've created a file test1.s with one function called loop1 with the code given by Olin below and just called it as shown in the code below:

 #include <p24F16KA102.h>

_FOSCSEL(FNOSC_FRCDIV  & FNOSC_PRI );
_FOSC( POSCMOD_HS  );
extern int loop1(void);
int main(void)
{
    AD1PCFG = 0xffff;   //make ADC pins all digital
    TRISA = 0;          //Make all PORTAs all outputs

    loop1();
    return 0;
}

Now the measured frequency at RA6 is about 335 KHZ. The loop is run every 1.47 microseconds (670 KHZ). This is, of course,  double the frequency above as the scope actually measures two loop cycles, the one RA6 is high plus the one RA6 is low.

Then using the info from Olin below the clock rate should be 12 X 680KHZ = 8.16MHZ.

The only thing I am not 100% clear is how the frequency of the instructions is defined, i.e,  should I have the time RA6 is high (or low) as the period?, then 1 instruction seems to be 2 ck cycles or.. should I use the time RA6 is high, then low , then back to high as the period? in this case then it should be 4 ck cycles per instruction.

Above is a matter of definition. My main question is answered as ( thank to all your  help from this forum)  I am positive the CK must be 8 MHZ, then,  I know the maximum possible frequency toggling a port PIN is about 335 KHZ with the ck at 8MHZ ( here I mean the standard definition of frequency). Also,  using the PLL I can be able to duplicate or cuadruplicate that rate.


texts: Can I use PWM signal to control devices that requires a system clock - OV7670

texts:
I want to use the simple camera ov7670 and that camera requires a system clock, called XCLK.

The clock requries 24 MHz input from a source that are at 50% duty call and a period of 24 nanoseconds.

Does this mean that I should use a PWM signal from a micro controller, or should I use an external crystal oscillator?
http://web.mit.edu/6.111/www/f2016/tools/OV7670_2006.pdf


texts: How to make a safe homemade 3D laser rangefinder

texts:
I'm trying to create a simple homemade 3D laser rangefinder using a generic line laser and an IR camera, similar to the setup described here. The line laser and camera would detect depth in two dimensions. I'd then mount these on a servo to sweep it across an angle to track the third dimension. My goal is to use it on a cheap indoor mobile robot for experiments with room mapping without spending $5000 on a "real" 3d laser rangefinder.

Being mindful of eye safety, I'm trying to find an appropriate line laser rated as class 2, but this has become quite difficult. The few line lasers I can find, like this one, give a description (25mW, 810nm, 5V) but don't provide a safety classification.

Based on this description of the safety classifications, the 25mW power rating would seem to imply it's a class IIIb, and therefore potentially quite dangerous:

  CLASS IIIb LASERS are systems with power levels of 5 mW to 500 mW
  (CW) and some pulsed lasers. These lasers will produce an eye hazard
  if viewed directly. This includes specular reflections.
  Administrative, Engineering, and PPE control measures are required.
  (Especially laser safety glasses!)

Does this classification and danger seem correct?

Since my application involves shining it around a home, I want to make sure it doesn't blind anyone. How can I ensure this is safe for home use?

Ideally, I'd like to find a 2.5-5mW infrared line laser, but no one seems to sell anything like this. Most seem to be 25mW or stronger. Could I control a stronger 5V laser's duty cycle by connecting it's +5V lead to an Arduino pin and generate a PWM output of 10% to give a 25mW laser an effective 2.5mW output?

Also, what minimum power would I need to make an effect laser rangefinder? Even if I did find a 5mW line laser, would that be bright enough to detect a couple meters away?


texts:
I've got a circuit with a CAN bus connector like the following with two RJ11 connectors to be connected in a daisy-chain style:

But only one of them is working (I tested them by connecting to another terminal node with a single connector). The soldering is correct.

When I measured the resistance between CANH and CANL with a jumper on each end, the working connector resistance was 60 ohms as expected, but'll be 120 ohms when connected to the not-working connector or with both connected. What'll be the problem in this case?


texts: LTSpice: 74HCT Library - Setting 74HCT74 D F/F Initial State

texts:
I am using the 74HCT library from the Yahoo user group. I currently have two 74HCT74 D flip-flops in my circuit but I do not know how to set their initial state (Q = LOW for both). Is this done in a spice directive, or is it done elsewhere?

I would include the contents of 74HCT.lib but I exceed the character limit. The files can be accessed from the link above, though, provided you are a member of the group.


texts: What kinds of batteries have the highest energy density?

texts: My question is, what kinds of batteries have the highest amount of watt hours per cm3? I know, comparatively, that for example li-ion batteries in phones generally have a higher capacity than, say, duracell rechargeable aa batteries. Preferably, I would prefer each individual battery to be under 5 volts, and not cost more than a hundred dollars.


texts: How do I use fuse bits on AVR to configure frequency

texts:
I compiled a hex file where the controller is supposed to blink 1 time per secound. The frequency was set to 1mHz (it is the internal generator). I programmed an Atmega 8a using avrdude 33 on default fuses and now the LED is flushing very fast. I think if I rise the frequency to 8mHz it will work ok. But I need the Atmega running as slow as possible to reduce power consumption. Because if i rise the frequency to 8mHz it will increase the power consumption 8 times! So how sould I configure the fuses?

P.S. I tried to use someone else's fuses and killed a few microcontrollers so I want to be sure that it will work 100%.


texts: Female 24-pin 2 row mezzanine connector break out board?

texts:
This is a bit of an odd one, but does anyone know if there exists a breakout pcb board with pin headers that adapts to a mezzanine connector? (I hope I've my terminology correct.)
I'm essentially trying to get a board that has a male connector that this (see picture below) cable can plug in to (24 pin, 2 row mezzanine connector, unknown pitch unfortunately) and convert it to a bunch of pin headers.
(That connector is part of a 3ds cartridge slot I'm doing something with, I could unsolder the cartridge slot and put it on a protoboard, but it'd be easier to just have a breakout board with headers.)


texts: How to use Boost Step-Up Converter MC34063

texts:
I am trying to use a MC34063 switching regulator to step-up 5v to 12v.

I have wired it up as shown below, I think its the same as the datasheet.

But I only get ~4 volts out.

I know the capacitors I am using are greater than what is in the datasheet examples, but its the closest I can get. I do have capacitors that are below the datasheet values too, but those don't seem to make a difference.

(I am eventually using this on a battery, but currently the 5v I am using is from a power supply (stable constant DC current))

What am I doing wrong? What can I try next?


texts: Equivalent resistance of a set of n resistors?

texts:
Is the equivalent resistance across a set of n resistors connected in series greater than the equivalent resistance across them when they are connected in parallel? I want to find the relation between \$R_s\$ and \$R_p\$.

My attempt:

Let the resistance of the resistors be denoted by \$R_1, R_2, R_3,..., R_n\$ and the equivalent resistance across the series and parallel combinations of the resistors by \$R_s\$ and \$R_p\$.

\$R_s=R_1+R_2+R_3+...+R_n\$

and

\$R_p=\frac{1}{\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}+...+\frac{1}{R_n}}\$

From first look it may seem that \$R_p\$ is less than \$R_s\$ but then on careful inspection it is not possible to ascertain which one is greater.


texts: What kind of capacitor is this? How to read its value code?

texts:
I have found some capacitors like this one:

Does anyone know what kind of capacitor it is? How can I read its value?


texts: Using smaller ram to make a larger ram unit?

texts: So far, I figure I need to divide the 2k x 22 RAM's into a 4 parallel connection to get the 3 bits data out, and I assume I'm going to need 3G/2K= 125000 rows of RAM, but I'm not sure out to set up the addressing in for the RAM.


texts: How do we get the proper USB charger for tablets with varying cable lengths and gauges?

texts:
We install tablets on walls that require a constant supply of charging power.
We use different cables with various lengths and gauges. Most of our installs use Cat5E so we usually use 2 conductors of that cat5E for the positive and 2 conductors for the negative.
I do know that USB chargers all have a voltage of around 5.4 volts and the usual chargers put out between 1 amp and 2.1 amps. We have used 2 amp chargers with charger cables as short as 15 feet and they do not charge.

Q. Is there a formula for determining the proper amperage for a charger output with the variables with the gauge and length?
Q. If not, how do I find a charger that will charge my devices with varying lengths and gauge of wire?


texts:
Specsheets I'm reading tend to specify maximum capacitance at 1V instead of 0V reverse voltage bias.

NXP BB series don't show anything below 1V in the tables and 0.5V in the graph.

Skyworks SMV series show a table of capacitance versus reverse voltage including 0V, but in the Electrical Specifications table, it still specifies 1V and not 0V.

Why is this? Do they assume that no one wants to bias the diode in the nonlinear region? Is the variance around the maximum capacitance so high that it's not even worth specifying?


texts:
Im currently trying to desing a class AB amp. I have currently got so far as bellow. I have the base voltages set at around 0.7V to just allow forward conducting of the BE diodes, and reduce crossover distortion.

My question is how come for my design I do not have any voltage gain? Or is this stage purely for current gain? Also, in most designs I see for a class AB there is another transistor on the input to the pushpull pair. Is this for the voltage gain? Like in AB class amp, design considerations. If so how could I implement this stage into my design. I will finally add a differential pair on the input after I complete this stage.


texts: Pull-up resistor value I2C; higher than 400 pf capacitance

texts:
I'm using 100 kHz I2C for communication with 12 slaves. I found that MAX capacitance is about 400 PF. when I calculate the pull up resistor value, it looks like i can go mucher higher in capacitance. Is this correct?

Using 5V, and VOL = 0.4V for IOL = 3mA

Rmin=5V−0.4V /3mA = 1533 ohm
This means I can go as low as 1533 ohm.

If C bus is 650pf

Rmax=1000ns/(Cbus*0.8473) = 1000ns/(650PF *0.8473) = 1800 ohm.

So If I choose a pull up resistor about 1.8K, It will satisfy BOTH Rmin and Rmax equitation. My Bus can handle up to 650 PF capacitance.

Is this correct or do I miss something? Why goes official specs for 100kHz maximum till 400 pf?

Thanks!!
All Equitations comes from official I2C specs
http://www.ti.com/lit/an/slva689/slva689.pdf

https://www.nxp.com/docs/en/user-guide/UM10204.pdf  P55

(PS: The  I2C devices I use can also handle up to 20mA IOL for VOL = 0.4V. This means that Rmin can be way lower; Rmin=5V−0.4V /20mA = 230 ohm. My bus can handle much more capacitance)


texts: What are some ways to isolate a TTL serial GPS device from high frequency noise caused by a processor and other peripherals?

texts:
I'm trying to interface a GPS receiver with a Minnowboard Turbot Single Board Computer via a ttl serial UART on the boards expansion header but there is a substantial amount of noise on the UART and power pins coming from the Minnowboard and it is causing very low SNR values in the GPS device and the GPS never gets a fix.  Moving the GPS device or antenna further from the board doesn't work, the noise is being transmitted through the header pins themselves.

What kind of circuitry do I need[0] to build to isolate the GPS from the interference on those pins?

[0] I've already tried putting ferrite beads on all the connections tx, rx, pwr, gnd to the GPS but it didn't improve the situation enough to get a GPS lock.


texts:
I need to interface a display which has an FPC connector. I'm a bit confused as to what is the pin pitch. The datasheet's drawing is a bit confusing because the dimension lines are a bit off-centered with regards to the pin's midpoint. If someone could help me out, that'd be great.

Datasheet of display


texts: I am designing a 7 segment display but I am finding it a little bit hard to associate them

texts:
I am new in this domain and I want to design a 7-segment display from 0 to 9 and then from A to F.

I made the truth table composed of 4 inputs and 8 outputs each output for the corresponding pin of the segment, then designed the k-maps and lastly I wrote the Boolean equation of each output.

The problem is that I don't know how to link each equation with each other.

So I asked this question like 2 days ago and arrived to a conclusion which ended pretty much what I want to do but there is still one small problem which is I don't know what to put as inputs like in the image below.

I tried to put inputs like the ones in the image, some of the logical circuits like "c" and "d" lighted up when the input is 1 and turned off when it is 0.
So if someone could tell me what is my mistake knowing that each logical circuit from a to g are all correct.


texts: Safest way to limit current output of a signal generator

texts:
I need to feed a TTL-like signal (0-5V) from a signal generator to another equipment (herein 'load'), whose manual states that the input current should be about 10 mA, and 30 mA maximum. As I work with 5 V, I'm thinking I should use a coaxial cable to get the output from the generator, then to connect a 500 Ohms resistance in series with the load, which should give me 10 mA of current.

I would like to know if this is correct, and if there's some safer way to do this, as the equipment I'm trying to feed this signal to is borrowed from another laboratory.

Updated to add the link to the equipment manual (page 34, section 3.13.1) http://www.biomech.hacettepe.edu.tr/manuals/FASTCAM_SA3_HW_Manual_Rev105en.pdf


texts:
I have read several documentations about switching losses in IGBT. Most of documents indicates to use Eon and Eoff curves to calcul the switching losses through the IGBT.

Nevertheless, the Eon and Eoff curves are obtained according to a very particular test setup which is working in CCM. Of course, my circuit does not correspond to this test setup. First observation, I m surprised to see that the Eon and Eoff are not influenced by the current capability of the IGBT driver?

About my circuit, I have several IGBTs in parallel. My circuit is working in DCM, so I have no problem of reverse recovery diode. Nevertheless the current collector is high at the instant of the turn on (Forward topology with "output buck converter" working in CCM).

I conclude that the Eon and Eoff curve won't help me for finding the switching losses. The best idea that I have is to simulate my converter through LTspice and extract the losses. I will try to include parasitic component into my simulation. Is there someone with a better idea? Is there someone who knows how to mathematically model the switching transition of an IGBT with tail current? If it was a MOSFET it would be a bit simpler to me but it will still be hard.


texts:
In class today we wrote a test in basics of telecommunication. One of the exercises was to identify an AM transistor modulator. I chose this one:

Note that the second branch of the node of the output capacitor is connected to a resistor and the resistor is connected to VCC. Is that correct? I googled it and found different results so help appreciated.


texts: Help with coreless micromotor. Can I add a switch?

texts:
I have ordered some coreless micromotors, as shown here.

These are for a science club for the kids to tinker around with. We are simply using them to make lightweight cardboard junk robots jiggle about (by taping them on). The motors are wired up to a 2xAAA battery pack.

I have two questions:

1) can I add a switch to this rudimentary circuit? Tactile switches would be ideal. I don't have a circuit board so I am not really understanding if this is possible with the pin system I have seen on most switches (such as these.)

2) Can I protect the very delicate wiring in the back of these motors? I have easily broken one just with lightweight playing. The kids will be a little more heavy handed.  I am thinking a blob of resin glue? Is there any reason not to do this?


texts:
I'm trying to build a diy pedal adapter for my digital piano. The piano has a 6x1 2.54mm pitch female socket header. It has a serrated side, and a little notch on the other side to secure the male connector.

Male connector:

A schematic view of the connectors:

What is the name of this particular pin header connector?


texts:
I was wondering if there was some specific method to finding the circuit for an xor with a variety of variables. Like, I can easily expand a set number of xor(2 inputs) and xor(3 inputs) but there has to be some way to minimize the number you use. So, say XOR of 17 variables, how would you minimally expand it, using the least number of and/or gates?

Thank you


texts: How to supply either 5V or 0V without the gradual PSU voltage bleed?

texts:
I have a 200W 5VDC power supply (Meanwell LRS 200-5). When I shut off the AC it takes about 60s for the supply to drain fully through the connected sensitive components (processors and storage drives).

When the supply is shut off I require either for it to drain within about 200ms, or to be "disconnected" from the load and it can drain as slowly as it likes. Basically, either 5VDC or nothing is supplied to the load. As a stopgap, I hold a power resistor to the PSU by hand each time I shut it off.

There are two loads in parallel so I can either introduce two protection circuits rated 100W each, or a single 200W solution.

Researched solutions:

An UVLO sounds promising, but I need to design one for 5V at the high wattage which I don't know how to do.

A Zener diode and resistor to drain the PSU, but I'd prefer to not introduce more resistance on the PSU as it's maxed already.

A relay that shuts off on low voltage, but I've only been able to locate automotive 12V relays at the power required. Also, I'm worried about back EMF as the relay shuts off so then I'd have to introduce more circuitry.

What solutions are used in the wild? If I could go with the simple Zener+resistor solution on the regulated 5V PSU, what values of Zener and R would I be looking at?

Update: The solution I’m adopting is the relay solution proposed by @Transistor:


texts: Question about the placement of resistors on a Marx generator

texts:
I'm a little unclear about why Marx generators are generally setup with their resistors like this:

What is the benefit of placing resistors where they are instead of having resistors in series with the spark gaps?  Are two reasons so that if the gap spacing for each of the gaps after the first is equal, they won't all fire at the same time and so there won't be resonating effects?  Part of why I ask is that it seems easier to model resistors in series with gaps in LT Spice, like in the simple model below, it gives a damped oscillating voltage as an output, but if I swap the two resistors, it gives me more of a ramp response.


texts: MOSFET saturation relation between Vgs and Vds

texts:
We know that:

$$V_{in} < V_{out} + V_{t0}$$
and
$$V_{in} >= V_{t0}$$

Where \$V_{in}\$ is the input voltage (say voltage gate source)

\$V_{out}\$ is the output voltage say \$V_{ds}\$ (voltage drain source)

\$V_{t0}\$ is the threshold voltage

  Say we are neglecting all the higher order effects and also assume that \$V_{sb}\$ (voltage between substrate and source) is zero.

Then is my logic correct of interpreting the above equation?

That \$V_{gs}\$ is proportional to \$I_d\$ (drain current) i.e. it sets a limit that it can be the maximum allowable current before the drain current saturates and starts to pinch off.

And \$V_{ds}\$ is also proportional to \$I_d\$. Hence when we increase the \$V_{ds}\$ the \$I_d\$ will increase and after some point it will start to saturate hence at that point \$V_{ds} + const\$ (\$V_{t0}\$) must be greater than \$V_{gs}\$ as \$V_{gs}\$ did set the upper limit on the amount of allowable \$I_d\$ before pinchoff.

Please correct me if I am wrong.


texts: USB 2.0 High Speed Device with Input Power Filter

texts:
I am working on a USB 2.0 High Speed Data device that will have a power input filter for EMI and overall power integrity. The filter includes inductors on both the +V and GND. So this means there will be high frequency impedance between the GND for the host and the device. Does anyone know what kind of issues this might create with High Speed Data signal integrity, what I should be considering to make sure the data rate doesn't get compromised?

Thanks


texts: Is it possible for an energy source of 4.7mW to heat a Nichrome wire to 800°F [427°C]?

texts:
I am trying to understand if it will be possible for an energy source with an output of 4.7mW at 47% efficiency to power a 35AWG Nichrome wire (think dime sized coil) to 700-800 degrees F.

If it is possible, how many seconds/minutes would it take to heat the coil?

Also would a capacitor be helpful with a 4.7mW output in order to store enough energy to heat the coil?

http://www.cecs.wright.edu/balloon/images/2/22/Nichrome_Wire_Heating_Element_Design_Basics.pdf
I initially used the chart above to give me a basis of the amount of energy required to heat Nichrome wire to 700-800F but I am too unfamiliar with conversions to know if this is possible.


texts: Are there any fully programmable DSP chips with built in ADC & DAC?

texts:
Using Analog Devices as an example. They have SigmaDSP chips with on board ADCs and DACs, but they are not very programmable. They are rely on a high level IDE with very standard audio processing blocks. Alternatively they have SHARC chips which are fully programmable, but no on board ADCs, DACs.

I want to make a custom embedded single channel audio autocorrelation algorithm, with as few external components as possible.


texts:
I have seen many tutorial of Multiplexing 74HC595 with led's Is it possible to control Stepper motor with 74HC595 ? And Recently i have found a board SSC-32 which control 32 servos, so is it possible to use it for controlling stepper motors.
As the project I am working on a Huge consisting of 100 stepper motor with accompanied Driver uln2003 to be controlled. It would be a Big help if anyone guide me to correct path How can I achieve it and arduino Uno will be the brain of the project.


texts: VHDL process requires multiple clock cycles

texts:
I wrote a simple counter in VHDL for a program counter. Everything is done in a process, but what I dont understand is that in the simulation, the addition of the program counter, is only done at the next clock event, rather than immediately after PCNext has been output.

Here is the code as well as the simulation:

 LIBRARY ieee;
    USE ieee.std_logic_1164.ALL;
    USE ieee.numeric_std.ALL;

    ENTITY dlatch IS
    PORT (
         Reset, Clock : IN std_logic;
         PC_out : OUT std_logic_vector(31 downto 0)
         );
    end dlatch;

    ARCHITECTURE d_arch OF dlatch IS

    SIGNAL PC      : std_logic_vector(31 downto 0);
    SIGNAL PCNext  : std_logic_vector(31 downto 0);

    BEGIN
    PROCESS(Clock, Reset)
    BEGIN
         IF Reset = '1' THEN
              PC <= x"00000000";
         ELSIF Clock'event and Clock = '1' THEN
                PC <= PCNext;
         END IF;

        PCNext <= std_logic_vector(unsigned(PC) + 4);

    END PROCESS;

    PC_out <= PC;

    END d_arch;

Do you see how PCNext is only calculated at the falling edge of the clock? Why isn't it calculated immediately after PC <= PCNext?


texts: Constant Current vs Constant Voltage Dimmable LED Drivers

texts:
For my circuit, I want to use 110VAC mains power, via a TRIAC dimmer to an LED Driver power supply.

For this use case, I am confused on whether to use a constant voltage AC to DC LED driver power supply, or a constant current AC to DC LED driver power supply.

When would I use one vs the other? Which supporting components would I need to drive the LED array?

I thought that if I used a constant voltage supply, using the formula R = (Vs - Vf) / I, I would simply put a resistor in series (calculated by the above formula) to be sure "I" (current) never exceeded the LED array's maximum forward current.

For the constant current power supply, would I calculate the minimal value resistor that when I was at Vmin of the LED power supply, it would translate to a current just below whats needed to light up the LEDs, and when its at Vmax of the LED power supply, well, thats the maximum current I would have at my disposal to light up my array? (So in this case, I would need to find the power supply with the ideal Vmin and Vmax to take advantage of the LEDs' power capacity?)

Let me know if I'm on the right track here, or if I am missing anything... thank you.


texts: Getting two way audio from/to a landline telephone, and making it ring

texts:
I have a "land line" telephone (ie. with an RJ11 plug) and a CSR8615 HFP bluetooth module (datasheet) — I'm looking to make my mobile's phone calls ring the land line phone, as well as being able to take the calls there as well.

I'm fairly confident I can get the Bluetooth board set up to collect a line in and send a line out, but I'm struggling to figure out how to make my telephone collect & send audio as well as making it ring.

There's a wealth of resources out there (the 'ringer' section in here looks particularly promising), but so many of these articles are old/incomplete enough that I'm finding it hard to tell whether they're about UK or US telephone systems, and whether I'll end up damaging something if I try putting a 80V peak-to-peak AC voltage through my phone, as is suggested here.

Can anyone offer a design or advice for me? (I'm a professional software engineer, so I can learn fast, but I finished my electronics A-level 10 years ago, so the EE side of things is rusty to say the least!)


texts: Current flow in ground plane of non isolated dc dc converter

texts: I am using an non isolated 12V dc- dc converter. Input voltage is 48VDC and and output power is 12VDC * 16A. Taking 95% efficiency of the module, input current will be 4.2A. I wanted to know the current that will sink to the ground plane of PCB. Is it equal to 16A + 4.2A ?


texts: Difference between implementations of a 4 bit counter in verilog

texts:
I was wondering if there is a difference between (two potential implementations of a counter in verilog with a case statement...

module counter_4(
    input clock;
    output reg[3:0] count;
    );
    always @(posedge clock) begin
        case(count)
            0: count = 1;
            1: count = 2;
            2: count = 3;
            3: count = 4;
            4: count = 5;
            5: count = 6;
            6: count = 7;
            7: count = 8;
            8: count = 9;
            9: count = 10;
            10: count = 11;
            11: count = 12;
            12: count = 13;
            13: count = 14;
            14: count = 15;
            15: count = 0;
        endcase
    end
endmodule

or with an increment...

module counter_4(
        input clock;
        output reg[3:0] count;
        );

    always @(posedge clock) begin
        count = count+1;
    end
endmodule

These may not even be working code, I don't have access to a compiler right now, but hopefully it's enough to get the idea across. Why (aside from the brevity of the increment code) would I use one method or another?


texts: Design of Fully Differential OTA Circuits

texts:
This is the equivalent model of an ideal single-ended OTA:

Now, this is the equivalent model of an ideal fully differential OTA:

Now, is there a rule for getting a certain circuit with a fully differential OTA starting from that of a single-ended OTA?

For instance, I have to realize this circuit with a fully differential architecture:


texts: Generally we give analog signal to ADC as input. As per my understanding, ADC has sample and hold circuit before voltage comparator. This sample and hold circuit samples the analog signal and hold for sometime. Here the signal may resemble like discrete signal. Now my question is that as input to ADC, can we give a discrete signal directly. If we give discrete signal as input, what properties we need to consider for the signal.


texts:
I'm trying to power the waterproof version of the DS18b20 Temperatur Sensor via the D1 (GPIO05) Pin.

I tested the setup first by using the 3.3 Volt Out Pin and by connecting a 4.7 Resistor between VCC and the Data Pin (GPIO04) and everything worked.

Now when I'm trying the same setup but with the D1 (GPIO05) Pin instead of the 3.3 V I only get the 85 °C Error reading as if it's not properly wired.

GPI05 puts out 3.3 V when set high so that should work. I also tried the setup with different sensors like the HR-SR04 Ultrasound and the DHT-22. They all work fine.


texts: Capacitive fluid level sensor design and insulation

texts:
This is a question regarding the measurement of a fluid level (in my case water) using a capacitive sensor. Capacitive sensors are a common topic, but I have one specific question: It is necessary for both electrodes to be insulated from the fluid?

This is the basic concept that I am intending to implement: Capacitive Fluid Level Sensor (Instructables)

In that sensor design, both the inner and the outer electrodes are insulated from the fluid. (Note the remark that the sensor only worked correctly when the outer electrode was the ground pole.

Original Instructables design

I would like to implement a simplified design where the outer electrode is an aluminium tube, and the inner electrode is sealed inside in a PVC pipe. (obviously with an electrical connection though!)

Concept design with uninsulated outer electrode

Hence my question: Is it necessary to insulate the outer electrode? What effect will it have on the capacitance of the sensor if the dielectric medium (i.e. the water) is effectively connected to the outer electrode? Bear in mind that we are only trying to achieve a measurable change in capacitance.

The following topics here are of interest:

Water Level Sensor Circuit (Curd's answer)
Water level capacitive probe topology
Water level: BIG capacitive level sensor with steel bars?


texts: How many secondary oscillators are connected to my PIC24F

texts:
I have a PIC24F Development Board an Explorer 16/32 with a PIC24FJ1024GB610 General Purpose Plug-in Module (Part # MA240023)

I would like to create a simple program where the clock signal would be sourced from the Secondary Oscillator (SOSC), I would like to use one of the external oscillators (32.768KHz) on the development board, as shown in the picture below.

This is from the PIC24FJ1024GB610's Datasheet

However this is what confuses, in the Explorer 16/32 schematic, crystal Y2 of 32.768 KHz is connected to the SOSCI (P73) and SOSCO (P74) of the microcontroller, and in the PIC24FJ1024GB610 PIM schematic, crystal X1 of 32.768 KHz is connected to SOSCI/RC13 (P73) and SOSCO/RC14 (P74).

A printout of the two crystal schematics is shown below.

do the SOSCI and SOSCO pins have 2 32.768KHz oscillators connected to it, or do we disconnect one oscillator and keep the other? (I don't see any jumpers).

Your help is highly appreciated.


texts:
There are several ways to implement the current/voltage control for an SMPS. The easy way I see is to use an ASIC/PMIC to manage the control loop. One of the other methods would be implement a PID control algorithm using a microcontroller and control the duty cycle of an SMPS.

I need some help in understanding the pros and cons of the above two methods in order to arrive at a justification of selecting one of the two methods.

Besides, if in case, there are control/communication/dimming requirements, then a PMIC with an MCU could also be used.

Please support me with some comparison.


texts: CAN Bus Debug MCP25625 CAN to SPI to USB (MCP2210)

texts:
I am trying to build a CAN - USB converter using the MCP 25625 chip to convert CAN to SPI first and then receive/send the SPI data on an MCP 2210 chip of SPI interface and consequently convert to USB.

So far I have been successful in interfacing the two chips and getting data across on each of them.

I set my BR of my CAN controller(i.e. MCP 25625 to 1 Mbps) which is coherent with the target device that is spewing data on to this controller.

The issue that I am facing is with the data that my target device sends,
I know it has a payload has some ASCII but the data that I receive on the CAN controller read through the SPI -> USB MCP 2210 chip, shows up in complete binary and also the number of bytes to be received lesser in number.

There is a CAN packet header that is also being sent prior to the payload but the spew of data that I receive has no ASCII whatsoever whereas my target device does send ASCII and I confirmed this using the commerical PCAN/USB adapter.

I set the SPI baud rate to 1 Mbps as well.

I am running into a block on where I should start debugging this.
Any help would be appreciated.


texts: Why is the voltage across the inputs of an ideal OP Amp zero?

texts:
The property that the voltage across the inputs of an ideal OP Amp is zero cannot be taken as an axiom because it isn't a property you can directly "adjust" (as opposed to say the resistance across the input terminals or the gain). It's a consequence of the properties that you can "adjust", hence it must be derived from these properties.
All proofs I've come across essentially prove it like this:

Let the voltage across the input terminals of an ideal OP Amp be \$V_{in}\$, the output voltage be \$V_o\$ and the gain be \$G\$. \$V_o\$ is given by:
\$V_o = GV_{in}\$
The voltage across the OP Amp is bounded by the voltage being supplied to it. Let the supplied voltage be \$V_s\$. Then
\$-V_s \le GV_{in} \le +V_s \$
The gain is a property than can ideally be fixed to any value, so taking the limit of \$G\$ going to infinity gives:
\$ \lim_{G \to \infty} \frac{-V_s}{G} \le V_{in} \le \frac{+V_s}{G} \$
\$\implies 0 \le V_{in} \le 0\$
Hence the voltage across the input terminals of an ideal OP Amp must be zero.

The proof above would only be valid if OP Amps were always linear, which isn't true. If the output is greater in magnitude than the supplied voltage, the OP Amp becomes saturated - the proof doesn't take this into account. In other words, the proof assumes that \$V_o = GV_{in}\$ which is false. The correct equation would be:
\$V_o = \begin{cases} GV_{in}, \space -V_{s} \le GV_{in} \le +V_{s} \\ +Vs, \space GV_{in} > V_s \\ -Vs, \space GV_{in} < -V_s \end{cases}\$


texts: How to detect if vacuum tube is overdriven?

texts:
I want to somehow indicate(with LED diode for example) to user when vacuum tube is overdriven (When grid voltage is greater or equal than cathode voltage).
My first idea was to connect a LED diode from grid to cathode, but I'm not sure if this is a good idea. LEDs have voltage drop of about 2V, and I need to detect if voltage is greater or equal.


texts:
Background:  I plan to use lpmx.5 under cap power but need a way to save the rtc registers to FRAM when the super-cap runs down.

Plan:  Use SYSRSTIV SVSH interrupt to wake up and save the counter, or use P5.6 to wake up if the power is restored.

Quote from manual:

  The following conditions will cause an exit from LPM4.5:

  A wakeup event on an I/O if configured and enabled. The interrupt flag of the corresponding port pin is set (PxIFG). The PMMLPM5IFG bit is set.
  A wakeup from the RST pin.
  A power-cycle. Either the SVSHIFG or none of the PMMIFGs is set.

  Any exit from LPM4.5 causes a BOR. The program execution starts at the address the reset vector points
  to. PMMLPM5IFG = 1 indicates a wakeup from LPM4.5, or the System Reset Vector Word register (SYSRSTIV) can be used to decode the reset condition (see the device data sheet).

and

Figure 2-2. Voltage Failure and Resulting PMM Actions not showing the power-down SVSH interrupt.

Revised questions:

Is the SVSH interrupt available at power-down between SVSH trigger
and BOR reset?
How do I detect a SVSH wake-up?
If a need IO pin P5.6 wake up - Table 6-10 does not mention PMMLPM5 by name.  Is this the LPMx.5 wake-up or $08 vector and is
this the specific one triggered by, say P5.6, if correctly
configured?
Can the SVSH trigger be used to save the RTC counters RTCCNT12 AND RTCCNT34?  (see below)

I needed to split question 1 in two parts as I can confirm that SVSH can be used by sampling SYSRSTIV == 0x0E at startup.  However, when I read the counters under SVSH they always return zero.  I have also confirmed this strange behaviour by triggering SVSH from the active mode.

Is this a hardware bug?  I am testing the code with a Rev B chip.


texts: Any way to handle replacement of unknown value components

texts: i have a board here ms-16751 ver1.3. The pwr connector has been pushed in and took with it two inductors and a cap located directly behind it. Could anyone point me in the right direction as to how could i determine safe values of the components i could replace the missing ones with. Scoured the web in search of schematics but no joy. Cheers


texts: Mathematically I have enough power but the power source don't seem like enough

texts: Lets say i want to reach a certain wattage of 2,500 W. But I run it off a power source which maxes out at 5 A and 20 V. But I step the voltage up to 500 using a coil or transformer and now 5A × 500V is 2,500 but thats a lot of power from a small power source. Is stepping the voltage up really going to allow me to get 2,500 W of power from 5 A and 20 V or am I calculating this wrong? I'm new to electrical engineering and it seem strang that I can have such a power increase just by increasing voltage/amps.


texts: Can I use a multimeter to measure voltage even if amps of circuit is too high

texts:
I need to measure circuits which I expect to be 12V 19A and 5V 44A

I've got a basic multi-meter which can handle 10A/ 240V

Can I use this multi-meter to measure only the voltage on the circuits? As the amps are too high; if I try to measure amps; my multi-meter will blow, but would just measuring volts be safe for the multi-meter?

Thanks


texts:
I am trying to communicate with IS25LP128F Flash IC via SPI on STM32F407.

Firstly, I tried to send RDID command as you see in the picture.How
to send commands and reading respond of them is explained in datasheet.

I use HAL library. When I checked low layer codes of "HAL_SPI_TransmitReceive or Transmit and Receive", I realized that there is a problem due to the Tx data register. The problem is when hspi2' pTxBuffPtr is load to hspi->Instance->DR, hspi->Instance->DR is always zero regardless hspi2' pTxBuffPtr' content.

Are there anyone to had this problem before ?

Ty.

Here is my code.

`void IS25LP128F_ReadID()
{
    spiData[0]=RDID;
    spiData[1]=DUMMY;
    spiData[2]=DUMMY;
    spiData[3]=DUMMY;
    StartSPI();
    HAL_SPI_Transmit(&hspi2, spiData,4, 100);
    HAL_SPI_Receive(&hspi2, spiData,1, 100);
    StopSPI();
    IS25LP128F.ID=spiData[0];
}`

Here is low layer code block of HAL_SPI_Transmit function.
 while (hspi->TxXferCount > 0U)
{
  /* Wait until TXE flag is set to send data */
  if (__HAL_SPI_GET_FLAG(hspi, SPI_FLAG_TXE))
  {
    *((__IO uint8_t *)&hspi->Instance->DR) = (*hspi->pTxBuffPtr);
    hspi->pTxBuffPtr += sizeof(uint8_t);
    hspi->TxXferCount--;
  }

spi setup

`

      hspi2.Instance = SPI2;
  hspi2.Init.Mode = SPI_MODE_MASTER;
  hspi2.Init.Direction = SPI_DIRECTION_2LINES;
  hspi2.Init.DataSize = SPI_DATASIZE_8BIT;
  hspi2.Init.CLKPolarity = SPI_POLARITY_LOW;
  hspi2.Init.CLKPhase = SPI_PHASE_1EDGE;
  hspi2.Init.NSS = SPI_NSS_SOFT;
  hspi2.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_2;
  hspi2.Init.FirstBit = SPI_FIRSTBIT_MSB;
  hspi2.Init.TIMode = SPI_TIMODE_DISABLE;
  hspi2.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
  hspi2.Init.CRCPolynomial = 10;

chip select pin setup

 GPIO_InitStruct.Pin = IS25LP128F_CHIP_SELECT_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(IS25LP128F_CHIP_SELECT_GPIO_Port, &GPIO_InitStruct);


texts:
I'm looking to design a 120-300VAC power meter that uses an isolated DC supply (5VDC to 5VDC by Murata, 5.2kV) with an isolated SPI interface (ADUM4154, optocoupler in the diagram.) The AC line and neutral leads coming to my device will be controlled by TRIACs (switches in the attached diagram.) What will happen if only the line TRIAC switches closed? I figure this will take the entire circuit after the isolation to line voltage, but am wondering if any serious problems will occur.
My ADC (op-amp in schematic) is only configured to take in voltages in the range of +/-2.5VDC, but am thinking this would be the equivalent of 'zero volts' since the entire circuit is now floating at line voltage.
Will the isolated output of the Murata still be able to generate its '5VDC output' relative to the line voltage, or will it just not work completely?
I guess this question is analogous to taking any benchtop DMM, setting it to measure AC voltage, and just plugging in line without neutral.


texts: Does 'make and program device' first perform a clean?

texts:
In MPLABX v2.00, I'm always scared of introducing some bug by not remembering to first delete all old object files.  I'm inspecting the output of the build process but do not know for sure whether everything in the /build (where debugging build goes) and /dist (where the release build goes) directories are being deleted.

make -j 16 -f nbproject/Makefile-default.mk dist/.../MyProject.X.production.hex


texts:
How do you tell what type a capacitor is, (e.g. MKT, MKP, Mylar)? Most capacitors probably don't have a datasheet. Also, if the capacitor has no markings/code, for example:

is it possible to guess the type of the capacitor?


texts: Crystal and oscillators for custom ATMEGA328P, is load capacitance needed?

texts:
I'm designing a barebones Arduino-like board (based on ATMEGA328P.) I'm picking the external crystal.
I need to design two board, one "classic board" that runs at 16MHz and a "low power" that runs at 8MHz.
Here are my picks about the oscillators.  I'm not sure if they need external (22pF) capacitors or not.

16MHz crystal: DATASHEET HERE
8MHz crystal: DATASHEET HERE

Can someone help me figure it out?


texts:
I need a circuit that fires a relay when it detects audio pulses from one channel of an mp3 player.  I'm going to record audio pulses in sync with the music to control a motor for mouth movement.

Its been 20 years since I've done this kind of stuff, so I need some help with this design.
This is what I'm thinking so far:

audio controlled relay circuit http://www.excellerate.com/images/acr.jpg

The idea is to convert the AC audio to a DC level with D1 , use C1 to smooth it out.  Set R1 so the transistor is just below switching on.

Does this look like it will work?  If so, what would be a reasonable value for C1?  Does it have to be electrolytic, or can it be ceramic?

Clarification - I'm mostly interested in knowing:
- will my design work?
- suggestions for improvement?


texts: Does a logic-level P-MOSFET need a gate resistor?

texts:
I'm quintuple checking something I'm about to order from a PCB house, so bear with me.

I'm using a P-channel MOSFET to power on/off a GPS chip. The chip's grounding is complicated, so I prefer to control it on the high side.

Here's the circuit:

With the wire going to the bottom being the supply to the GPS chip, and GPS_EN going to an ATmega2560.

Can someone confirm that this is wired correctly, and that the gate resistor R22 is needed? I'm pulling the gate to the source voltage to default the switch to closed, and then driving it down throw GPS_EN to enable it. I'm going to use something like this MOSFET which has a Vgs of 1V. The ATmega runs off the same 3.3V, so there are no voltage differences there.

EDIT:  The GPS is expected to have a draw of about 75mA.


texts: How can I do quicker sensorless FOC startup?

texts:
In my current implementation of sensorless foc startup I run the motor open loop using a constant current for a preset time and then try to close the loop. Currently I'm able to do this within 400ms but I'd like to shorten this time further and preferably have a routine that can start the motor with maximum torque right away most of the time.

My implementation is very similar to the one described in this app note: http://ww1.microchip.com/downloads/en/AppNotes/01078B.pdf

The rotor position is estimated using sliding mode observer and stabilizes after a while of running the motor open loop.

I'm a bit concerned though about the reliability of such startup and the fact that it takes 400ms and does not deliver maximum torque when the rotor is not aligned. What other ways can I use to achive quickest startup with maximum initial torque on this type of setup that does not use any kind of position sensor?


texts: Symbol for ideal voltage source vs symbol for real voltage source

texts:
Wikipedia's article on Voltage source shows the figure below. It says in the figure that the following symbols is an ideal voltage source.

However, elsewhere in the same article they have a circuit using the same symbol, and they call it a real voltage source.

I need to make some illustrations for some teaching material, and I need to make the distinction between ideal and real voltage sources. How do I do that? Do I need to add a small label to each circuit diagram explicitly stating whether it is ideal or real? Or can I communicate this clearly by using symbols?

If possible I would like answers to refer to standards or other canonical sources if there are any.


texts: Is there a component that will OR the last 1-2ms of its input?

texts:
I need a component/circuit which will output 1 if a 1 has been input at any time in the last 1-2ms.

I could make such a circuit out of several shift registers, an oscillator and several OR gates, or I could use an MCU.

Is there a simpler (maybe analogue) alternative?  I've considered:

bus -->|--+--+-- out
          |  |
          =  R
          |  |
          _  _
          -  -
                           _
>| diode    = capacitor    - GND    R resistor

but the 1V diode drop is quite big, making the circuit very sensitive to the bus being driven at less than 3V3.  There may be slew issues, with the output component not recognising an edge.

Maybe a 555 can do this?

The required logic looks like:

       _                          ____   _   __
bus __| |________________________|    |_| |_|  |______________________
       _____________________      _________________________________
out __|                     |____|                                 |__

        |<----- 1-2ms ----->|                  |<----- 1-2ms ----->|


texts:
I am wondering, why is there no complementary transistor pairs to buy, since their use as individual devices is pretty common in audio amplifier applications.

So for complementary transistor pair it is desired to have as identical properties as possible (gain, bandwidth, breakdown voltages, etc.) - it is hard for an amateur like me to find two very closely identical transistors (one pnp and other npn; for BJT lets say).

Are there any (power) complementary transistors available in any electronics shop? If there are any, example of them would be great!
If there are no such transistors in one package sealed together, why is there no one manufacturing such components?

One more thing. I have recently bought a lot of cheap npn and pnp transistors of same model (npn->BC337 & pnp->BC327). I have found two almost identical transistor, as the thing concerns of the gain which is approx. 320 for both. Sadly transistors are low power and cannot be used in power amplifier in the driver stage, where currents get amplified to greater levels (1 amp and above).

I kind of modified these two transistor so I can use it (two pieces in one) on the breadboard - if one starts heating, the other also starts heating for the same portion; making them work in as identical conditions as possible.

What do you think of this "modified version" of two transistors as one transistor? Bad, dumb, nothing special, awesome?

Transistors are pulled together with thermal shrinkable tube :D


texts: How to build a 15,000 Gauss hand-held electromagnet

texts:
I'm wondering if it's possible to build a small hand-held electromagnet shaped like a solenoid that is possible of producing a field of 15,000 Gauss.

I'm familiar with the formula for the strength of a field produced by a solenoid: field strength = (permeability * number of turns * amperage) / length.

By my calculations, if I can get a core with a u of 10^(-3), amperage of 5 from a Gates 5 amp-hour battery, and a length of 5cm, I would only need 15 turns.

Am I on the right track?


texts: It's probably a pushbutton, but what does that arrow represent?


texts: Difference between surface current and current density?

texts: Actually my problem is with the direction of both. I use CST to simulate a patch antenna. I guess that current density is the classic vector field \$ \mathbf{J} \$ (A/m^2) and actually follows the direction of the E-field. In my case, the patch antenna is placed on the yz plane. The current density direction according to the simulation is towards x-direction. On the other hand, the surface current has a completely different direction, actually towards y-direction. Practically, it follows the direction of the input transmission line of the patch antenna. Can you explain to me why they have a completely different direction?


texts: How does an electron beam move in XY mode?

texts:
I was recently observing some Lissajous figures on an analog scope in XY mode .
I was wondering how does the electron beam move . I know it should move from left to right but I find it difficult to imagine.

It's easy to think that the beam sweeps left to right whilst moving up and down while plotting say, a square wave . But how does it plot an ellipse or similar loop-like figures ?

Thanks in advance!!


texts: How can I use two TP4056 with two li-ion batteries, but single load?

texts:
I have two TP4056 modules (with protection circuit), which I am using to charge two batteries respectively, off a single power line. The modules are the ones that have charge output (B+/B-), and another regular output.

I'd like to be able to use both batteries (increased capacity) to power a single load, even while charging. The batteries are rechargeable 3.7V 16340 Li-ions, same make and capacity.

I'm not sure how to do this in a safe manner. I don't know if it would be safe to conjoin the outputs with this module, and I would like to avoid using diodes because of the voltage drop.

The question is:
How can I make this work, in order to be able to use the device even while charging, and how can I connect the two batteries safely to the device in the first place?

My use case is described in the image.

EDIT: Look to the comments for an answer regarding more than two cells. As the original question was for two cells, I had to choose one of two valid answers.


texts: NPN transistor won't saturate when Vcc is greater than 7 volts

texts:
Am I missing something here?

I have an NPN transistor (2N2222) with a 10K resistor from collector to Vcc.

Also a 10K resistor from base to input signal. Emitter is grounded.

The base input is alternately connected to Vcc for saturation (Vce close to zero volts) and connected to ground for shutoff (Vce equal to Vcc).

The circuit works fine if VCC is less that 7 volts. Above that when the base input is grounded Vce does not increase above 7 volts. I have increased the value of Vcc to 15 volts and Vce is still 7 volts.

I want to have the transistor operate as a switch with Vcc at 12 volts, but it will not shut off. I have used several NPN transistors and they all show the same characteristic with a max Vce of 7 to 8 volts.

Is there a workaround for this?


texts: What's an easy way to connect multiple pins between multiple breakout boards?

texts:
I'm building a circuit by screwing multiple breakout boards into a wooden panel and using jumper wires to connect header pins between different boards. Most of the time this works fine, but sometimes I need to connect a pin to more than one other pin. This can easily happen with i2c, power, or ground.

On a breadboard this would be easy, but I don't have room for one, or at least not full-sized. I could also use solder to bridge some header pins together and make a sort of bus connector, but I don't see a nice way to mount it to keep it moving around. Or maybe I could solder multiple wires together, but that seems likely to result in a tangle.

It seems like this is something people would commonly want to do and there should be a more elegant way, but I don't know the search terms to look it up. What am I missing?


texts:
I hope this question meets the standards of this platform, if not please inform me of how I can improve it.

I was trying to design an antenna and I have done so. I am planning on using this antenna in an RFID application inside a metal container measuring in at 2.89m by 1.89m by 5.2m (WxHxD). Whereby this antenna designed is the RFID reader's antenna and is mounted inside the metal container as shown in the picture. This reader's antenna will detect RFID tags which are placed on pallets and inserted in the container.

My problem statement:

I am investigating the EM-field created from this antenna in the container using CST software. I want to monitor how this antenna behaves in this environment. My antenna measures in at 8cm by 8cm with a gain of 2.37dBi and an axial ratio of 1.5 at the resonant frequency of 915MHz. I have performed the simulation and I applied an E-field probe in the container and I got the following graph. The probe location is shown as a green arrow in the picture. Can someone help me in interpreting these results in the graph?

At 915MHz the E-field measures at 22.3dB as shown in the graph.


texts: I'm making a Nixie Clock and I had to buy from ebay some old SN74141 (KM155ID1 equivalent). Is there some newer IC which does the same things as this one, or similar, that I could get from big suppliers like Mouser, LCSC or DigiKey?


texts: LTC6102 - transient response, error of the simulator?

texts:
i'm building a device that has to measure current high side for 3 different scales: 1uA to 1mA, 1mA to 1A, 1A to 10A.
what i'm doing is to use a current sense amplifier from Analog devices - LTC6102 (https://ro.mouser.com/datasheet/2/609/6102fe-1279477.pdf) and three different shunts for every scale: 500 ohm for uA scale, 0.5 ohm for mA scale and 0.05 ohm for A scale and a gain=10 (R3/R2).
in order to comute from one scale to another i'm using DPST relays (to minimise the error of reading due to voltage drop across contacts).
during simulations i observed something strange:
when i connect the device to supply there is an output current spike that is over the limit of output current.
my question is if i miss something in designing of the circuit or the LTspice is playing with me :( .. ?
to be more clear what I did is:

look what happens when i bring supply voltage to 12V and i commute the relay (this happening with a delay of 10ms):

there is that spike of voltage that is clamped by that schottky diode.
i thought that there is a problem if i don't connect the input terminals of LTC6102 ... i tried to disconnect one of the terminals:

hmm ... maybe is because the PMOS (inside LTC6102) is going into ohmic region ... let's see what's happening if i will not allow this thing by setting relays to be closed when the circuit will be supplyed ... but the spike is still there!!

i would really appreciate some feedback!!
thx ;p


texts: Isolating Bi-Colored LED from MCU/Arduino

texts:
I'm currently trying to implement an opto-isolator into my project currently I have my code to run perfectly with out the implementation, but I was wondering how I can effectively control my RG LED (which I am restricted to using a common cathode)

I know my schematic is wonky :p I was just trying to properly interface my opto-coupler before I change my schematic.

Basically I want to know if there is a way to control the RG LEDs based on if I output from my Green or Red terminal of the Arduino with one optocoupler.
(I will be implementing up to 12 RG LEDs and have a few 4-channel isolators)

Thanks in advance!!


texts:
what will be the voltage at Vx if D1 and D2 are practical diodes

This is not a problem from some text book. This circuit came in my mind while i was studying differential amplifiers.


texts: Unable to access the module error while trying to simulate a simple PLC Lad program

texts: I am learning PLC and trying to simulate a simple program on Schematic Manager. But I'm having this error that says Unable to access the module CPU314c-2DP via the online interface. How can I solve it?


texts: If you have two identical but oppositely wound inductors does the inductance effectively cancel?

texts:
I was just curious if the effect inductance of a branch of a circuit would cancel if you put two identical but oppositely wound inductors in series. It's not something I have come across.But looking at the change in signs I imagine this to be the case.
Someone mentioned it to me regarding wound resistors in a circuits, and splitting them into 2 resistors in series, with opposite winding to reduce/attempt to cancel the inductance.

I have also recently needed to place several surface mount inductors in series, and I have no way of identifying which end is which, or the winding directions. They are not all the same make or model.And I have had difficulty measuring their inductance.


texts: I've used "touch lamps", where you turn it on and off by touching the lamp.  As I understand it, this works by putting a small electrical voltage through the human body: touching the lamp completes the circuit, allowing electricity to flow from the lamp to the ground.  Is this safe?  What makes it safe?  Is it because it is using very low voltage?  Do they have special circuitry to protect people?


texts: Output in unknown state even though specified in verilog

texts:
I am having some troubles with creating an edge detector in verilog. So far I've come up with this:

module edge_detector (
        input     ce,               // Clock enable.
        input     data,             // Data signal for edge detection.
        output reg detected,        // Output signal that goes high when edge is detected.
        input     reset,            // Active high reset.
        input     clk,              // Clock.
        input     [1:0] edge_sel,   // Edge selection. Look in description for details.
        output     sim_prev_data    // Simulation variable. Previous data state.
    );

    reg prev_data = 'bx;    // Previous data signal level state.

    always @(posedge clk) begin
        if (reset) begin
            detected <= 0;
            prev_data <= 'bx;
        end else if (ce) begin
            // Upon initialization or after reset prev_data state is unknown.
            // So after first clock tick prev_data is set, but detected output
            // should stay low.
            if (prev_data == 'bx) begin
                prev_data <= data;
                detected <= 0;
            end else begin
                case (edge_sel)
                    'b00: detected = (prev_data == 0 && data == 1);     // Rising edge.
                    'b01: detected = (prev_data == 1 && data == 0);     // Falling edge.
                    'b10: detected = ((prev_data == 0 && data == 1) ||  // Any edge.
                                      (prev_data == 1 && data == 0));
                    'b11: detected = ((prev_data == 0 && data == 0) ||  // No edge change.
                                      (prev_data == 1 && data == 1));
                endcase

                prev_data = data;
            end
        end
    end

    assign sim_prev_data = prev_data;
endmodule

Picture represents simulation waveform generated by iverilog and gtkwave. As can be seen when reset=1 also detected=0 and prev_data=x. When reset goes low and on first rising edge of a clock tick, marked by red line, detected has a value of x. Even though I have explicitly defined detected<=0; under ...if (prev_data == 'bx) begin...,

Why doesnt detected have a value of 0 after reset?


texts: Disabling digital input buffers on output only pins (PIC18)

texts:
Not really a problem, just curious.

I'm using a PIC18LF13K22 and the datasheet mentions that I can disable the digital input buffer for a pin by setting its corresponding bit in the ANSEL register.

Since I'm using some pins as digital outputs only, would I gain anything (less power usage?) by disabling their digital input buffers?


texts: LED blinking using LM358 operational amplifier

texts:
As an exercise in getting more familiar with op-amps, I have built this blinking LED circuit:

With the values above the circuit works fine on the breadboard, and in the Falstad simulator:

Simulation

If I change R3 to 5 MΩ however (trying to increase the time constant), the simulator still works however the breadboard version doesn't. I assume this is due to the current being too low through the capacitor, and parasitic effects or leakages taking over (e.g. if I put a single multimeter lead on one of the capacitor's pins the circuit starts working...).

My question is: Is there anything I can do to improve that circuit to get slower blinking rates? I am doing this as a learning experiment, so I want to keep the LM358 / single power supply core setup.

I have large electrolytic capacitors that I could use, but I don't know how to avoid the reverse voltages.

Other suggestions welcome - thanks!


texts: What could happen if I plug into my Arduino an AC adapter instead of a DC one?

texts:
I´ve read that Arduino needs a DC adapter and not an AC one, I know that.

What could happen if I plug into my arduino an AC adapter?

I need to do a quick test with two small 4.5v DC motors, and I only have at hand an AC adapter of 12v/1.5A (the center pin is positive), and I don´t want to fry my Arduino Mega...


texts: DC-DC boost converter using multisim. Output voltage keeps changing with input voltage

texts:
Link to circuit schematic simulation

The circuit is from the above link. There is some problem with the control loop. The output voltage doesnt stay constant within the input range of 12-24v for which it is designed. Even for any simple boost/buck circuit I am having the same problem with the control loop.


texts: Confusion on ARM-Tiva PORTS and Registers

texts:
So im learning the Edx Embedded course "Shape the World", it's very good so far and im really learning a lot.

Im in the section (6) learning about Ports and Registers. And maybe im a bit confused at what a "Port" exactly is.

Here is a quick capture from the "Ports" table (Specifically Port F which we are using): PORT F

I mostly understand the registers, They are 32 bit (With most bits being reserved besides the first 8 (0-7). Like DEN enabling pins and so forth. But I guess Im confused in this instance.....what is a PIN, and what exactly is a PORT?

these are parallel ports right? Would the Serial Ports only have..2 registers with less than 32 bits (since tx/rx/clk is all you need on serial right?)

maybe im just a bit lost at functionally what the PORT vs PIN is. I understand what a register is (32 flip flops basically in this instance), but im making sure I understand the fundamentals before I go any further.

Secondary as a question, why does the image I attached show like 5 DEN registers for 1 port? What would be the point of that?


texts: Best way to solder to a relay pin requiring ~30A of current?

texts:
On our hot tub circuit board, a trace on the PCB finally got cooked... Quite little damage, actually.  The one trace is blackened, and the PCB now has a hole in it, but otherwise, everything looks okay.

I have since purchased a new relay (the old one seemed to be fine, but I decided to get a new one since it was only $5).  The issue is that the copper trace that the relay was previously soldered to now isn't there anymore.

So, long story short, I'd like to know the best way to solder the thick gauge wire (I'd estimate it is 6 or 8 gauge) straight to the relay pin so that it can handle the ~24A (the heater coil is 10Ohm, supplied by 240V).  This will save $400. This hot tub is now a Frankenstein, but all the issues so far have been fixable.


texts:
I'm a student in Computer Sciences and am currently preparing myself for an Exam in Electronics. I came across this Exercise:

(U_0(t) = 10V), u(0) = 0V)

I don't have any solutions for the exercise, which is why i'm asking here:

The exercise is to calculate the time constants as well as the end values for the capacitor-voltage ( u(t) ) in case of a charging or discharging the capacitor. It seems to be an easy task in case of the discharging: The capacitor can only apply it's voltage to R_2 because of the Diode, so tau_1 = R_2 * C. Also the end-value for the charging-procedure (for me) seems to be equal to the z-voltage.

But what about the time-constant for the charging-procedure? We're assuming, that the diode and z-diode are absolutely ideal here. So modeling the z-diode with a voltage-source and a resistor r_z of 0 Ohm would lead to a short-circuit when calculating the pre-resistor for the capacitor!

What am i missing here?

This is my first post here and i would consider myself not really experienced, so take it easy on me!


texts: How does a latch determine its initial state?

texts: How does a latch get its initial state? I'm guessing that it depends on race conditions and which ever condition comes first then that is the state that the latch starts off with.


texts:
I'm disassembling a Sega GameGear.

The capacitors inside are all rated 50v  or lower, so it shouldn't be hazardous in that regard (I will discharge them anyway just to be sure).
However, the metal plate that covers the fluorescent tube of the screen, has a big "CAUTION: HIGH VOLTAGE" on it.
Does it refer to the voltage of the capacitors nearby just to be precautios? Or is the actual tube under the plate dangerous?
Does it store high voltage like a capacitor?
Should it be discharged in some way before being touched?


texts: Abstract signal and noise model for a logarithmic image sensor

texts:
A conventional grayscale image sensor pixel can be modeled as a "light bucket." Photons arrive on the sensor pixel for a fixed exposure time. The light bucket fills up with photo-electrons linearly proportional to the number of incident photons until its full well capacity is reached. The final readout is a Poisson random variable (shot noise) plus some Gaussian perturbations (due to quantization, dark current and readout noise). This model, although abstracted away from the underlying analog pixel electronics, is a quite useful model of signal and noise in a conventional image sensor pixel.

I am trying to build a similar signal and noise model, abstracted away from the pixel's MOSFET microelectronics, for a logarithmic image sensor (similar to Section 2 in this paper by Hasinoff et al. or Figure 1b of the EMVA 1288 standard.)

Is there any notion of saturation for a log pixel?
How does shot noise come into play in the logarithmic non-linearity?
Is there any notion of "exposure time" or "integration time" to average out shot noise in a log pixel?
Is there an EMVA standard (or some other standard) for log sensors (and more generally, for sensors non-linear photo-response, such as a quanta image sensor)?


texts: Why is it not sensible to connect many (MOS) transistors in series?

texts: For example a NAND-gate with 3 inputs has 3 NMOS in series and 3 PMOS in parallel. But why aren't there cmos gates with e.g. 10 inputs?


texts: What's the damage incurred by the chip on this photo?

texts:
The "generic error" page features this damaged chip with some kind of cavity:

I guess it's some typical damage, but I have no idea of what it might be.

What's the damage incurred by this chip and how is such damage typically incurred?


texts: Using a TFT display that has no controller

texts:
I have been using LCD screens (with the controllers) for my projects for a long time.  Now I thought of learning how these screens actually work, the part before they go to the controllers.

Well the idea came to my mind when I managed to scavenge an old working screen out of my old tablet. It has 60 pins and I managed to find a datasheet for it.  The model number is: AU OPTRONICS A080SN03 (datasheet here).

What does each pin of a 60 pin TFT display do?  And how can I use it?


texts: What is the silver strip behind crystal in the PCB?

texts:
Consider:

I came across a PCB, and I found a silver strip behind the crystal. What is that strip? Has anyone used it?


texts: Discarding divergent sensor data from running average

texts:
I'm building a inductive vehicle loop detector. By measuring the frequency of a LC-oscillator where the cars will pass over the inductor of the LC-Oscillator.

If the cars pass over the inductor the frequency will change over time according to one of the following profiles.

The frequency will also slightly change / drift based on environmental variables: like temperature, humidity or other variances in the environment of the loop.
To filter these last variations out, I used running average and std_variation based on: This post/comment on stack exchange. And was planning to detect vehicles when the frequency would go too many standard deviations away from the average.

The measurements made when there is a vehicle present shouldn't be added to the average calculation. This is easy to do when a certain threshold is passed.

But the problem is when a car is approaching the frequency will start to change but hasn't yet passed the threshold so these samples are added to the statistics. When a car approaches very slowly the standard deviation will be changed so much that the car will never be detected.

What solutions / alternatives / suggestions do you have to detect approaching cars and discard the values from the statistics for the reference empty loop.

Thanks in advance

Update

- Link to the post in the DSP section


texts:
I want to use an Arduino Nano to controll an LED strip using an WS2812B IC. The strip takes 5V at 3.6A. I want to power the arduino and the strip using two 18650 Li-ion batteries (LGDBHE41865), which can deliver up to 20A per cell. These batteries are unprotected and I think I need a protection board, that allows enough current to flow. However, I was unable to find one. It would be nice if someone can point me in the right direction. In addition I need a buck converter to step down the voltage from the batteries (2*3.7=7.4V) to 5V. I found some, but all of them have 3A limit which isn't enough for me, so I need some suggestions there too.

I'm new to this stuff, so maybe there's a simple solution I can't think of.
It would be nice if someone can tell me how to do this right. Thanks.


texts:
I'm looking for a way to make a swarm of sensors know their position using low cost, low power system (ie ESP32.)

Requirement:

low cost per device
low power use on devices
1m accuracy is enough
2D only
1 position every 5 sec is enough
500x500m area
only the device has to know its position
there is a permanent one way data broadcast connection to the devices that we can use (no ways for the device to communicate with the server)
the setup on the field like installing beacons and control system could be expensive (only the devices must be cheap and low power)

Time of flight on devices seems too power hungry and expensive to me. Computing offset like GPS does also.

I thought about a solution:
 - Using three beacons on the corners.
 - The server send a message saying "next time you get a positioning signal it means you're on row 1".
- It wait a bit to be sure all devices get the information.
 - Then ask the controler to send a message from a pair of beacons with just the right time offset so their signals meet on row 1.
 - All devices that are on row 1 get signal from both beacons at the same time.
 - They now know they are on row 1.
 - The process is repeated for each row.
 - Then for each column using another pair of beacons.

This approach does not require time of flight chip nor guessing the offset on the device side. Just detecting a match between two pulses. It's quite easy to make a AND logic door (a transistor) between two antennas for two different frequencies.

I'm not sure the signal will meet along straight lines, more like hyperbolic curves, some math will convert to x and y.
We can sync the beacons with one master antenna. There could also be  master antennas on each rows and columns. So there's no need to mesure time offset.

Do you think this is a good approach? If you have some links that would help me. I'm wondering how to precisely control the offset between emitted signals.

Edit : I changed explanation to make it more clear as comment requested.


texts: Some of LEDs connected in series remain on

texts:
I know that even tiny leakage currents can make an LED glow weakly and there are many answers to similar questions, but my problem is different.

I have 6 power LEDs connected in series and they are driven by an AL8860, which is basically a current regulator that uses a low side switch. When I apply a low voltage to the driver‘a control pin the LED current is supposed to be off. But actually some (not all) LEDs remain dimmed while the others are completely off.

How can that be? Even if the driver leaks some current, how would that only affect some LEDs?
As they are connected in series I would have expected them all to be in the same state.
The only explanation I have is that there are further leaks on the pcb, but that‘s hard to imagine, because there are almost no voltage drops on the pcb. The LEDs are assembled on an aluminum pcb (1oz, 0.3mm spacing).

Are there any tricks to force the LEDs off, beside shorting them (which is common practice with laser diodes)?


texts: Can I "trick" a PC Powersupply to power something other than a Motherboard?

texts:
I have a generic PC powersupply I'm using to power a BFL ASIC Bitcoin Miner.  It takes an input similar to a PC Video card with two connectors that look like this

Connector 1   Connector 2
 OOO           OOO
 OOO           OOO

The generic PC PSU requires a motherboard to send power to the AUX outputs.  Is there any way I can "trick" the PSU into powering the rest of the other devices safely?

Suppose there is no DIP switch to press, can I just connect one pin of the Motherboard output to ground?  (or similar)

I'd prefer to do this with no additional soldering/resistors etc.


texts:
I am performing some experiments to drive n different inductive loads using the following circuit based on the PIC16F690.

The Power Supply part:

12VAC and 24VAC come from the same power transformer. Regulator is 7805.
VSS and GND are common Grounds.

The control part:

A PIC16F690 with a Darlington array and a Schmitt trigger inverter are used to drive n inductive loads (Contactors CTC 1 ... CTC n).
The 24VDC relay is used with an external AC Contactor to switch a 400VAC 3Ph Motor
**The PIC and Schmitt trigger Vdd and Vss pins are not shown here due to Proteus limitation, same for the ULN2804 GND PIN ** however i included additional 100nf ceramic capacitors between Vdd and Vss for both of them with the minimum leads possible.

The inductive load part:

The above circuit apply for each Out1 ... Out n output in the ULN2804 to drive multiple inductive loads.

Notice that all the circuit shown to you here are in the same single face PCB.

Problem encountered:

After burning the circuit in a single face PCB i faced no problems and everything was working as expected until i realize that if i switch the Power supply OFF then ON the PIC won't starts and looks like blocked until i perform a hard reset using the MCLR button (sometimes i need to push the button multiple times !) after that the PIC get back to life, and everything return to normal.

I use the following FUSES XT,PUT,WDT,NOPROTECT,BROWNOUT,MCLR

What i did try so far:

Trying different type and values of capacitors near the PIC VDD/VSS and 7805 power regulator as i suspected a bad decoupling but without success.
I found out that when i switch the power OFF then ON before the Capacitors in the circuit discharge (last about 1 second), the PIC work without problem at the first shoot.
I found out too that when using the PIC in the same PCB to flash only some LEDs using some sensors or Potentiometers, everything is fine, however, if i switch one inductive load or a relay, the problem shows again.

As I'm only a hobbyist and printing PCBs is expensive in my region, i really need your help to find out what is wrong to avoid such problems in future. I'm curious to know what is the cause of the problem. Can anyone tell me what could be wrong here, please?

Thanks in advance.


texts: 555 astable operation not getting stable frequency

texts:
I needed a 38 kHz wave no matter the shape. So I started off with a 555 timer to produce a 38 kHz rectangular wave using its astable mode. Here's the circuit:

For that I used R1=9.8kohm, R2=17.6kohm, and C=820pF. At the beginning, the frequency I measured was right at 38.2 kHz but as time passes by the output frequency started scaling up for as much as 2 kHz. I mean, the frequency increased by 2 kHz in less than half an hour. I tried to change the type of the capacitor just to make sure that the capacitor was ok. But I didn't get a constant freq. either. Maybe it's with 555 timer that makes it behave like that?


texts: What happens when we connect two identical batteries in parallel with a resistance R?

texts:
I read somewhere that the voltage stays the same(it will be equal to the voltage of one of the batteries) but the output capacity increases. What does this mean? Will the current in the resistor increase?

Applying superposition theorem I see short circuits and therefore almost zero current going through the resistor. Am I right? So where's the increase and again what is output capacity?

We have something like this with a resistor across AB:


texts: Amplify and impedance match a low voltage signal

texts:
Situation: I am trying to trigger an external generator using the 1 Pulse Per Second (PPS) off a GPS receiver. The GPS receiver outputs a ~3.3Vp at high impedance once per second once the GPS receiver has reliable position. In order for my external generator to recognize the pulse, the input must be greater than ~3.6Vp and have a low impedance (~50 ohms).

Since the reference 1PPS signal is triggering an external generator, this circuit must have a very small time delay.

Does anyone know of a "simple" circuit to achieve such a job?

Thanks!


texts: Adding more LEDs in the strip causes white to become red-ish

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I have an LED strip with 62 LEDs. The type of the LEDs is WS2812B. I am powering them with a 5V 10A switching power supply.
When I set the LEDs to white and full brightness, they look a bit red-ish. I know that this might happen when the voltage drops.
Why does the whole strip become red-ish? Aren't only the LEDs at the end supposed to be affected?
Why would this happen with only 62 LEDs anyway? I have a 1.5m cable between the LED strip and the power supply. Could that be an issue?
I should note that when there are only 41 LEDs instead of all 62, the white looks fine.


texts: What does it says the transconductance efficiency (gm/Id) in an amplifier?

texts: I understand the concept of the transconductance but it's not clear what does the transconductance efficiency (gm/Id) mean. Since gm is the variation of Id to the Vgs or vin voltage... What is the variation of Id to Vgs by Id???


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I'm currently building a triangulation-based laser rangefinder with a camera and a number of laser pointers.  Something that I'm interested in doing is using the strobe output from my Point Grey FireflyMV to trigger the laser, so that it is only on when the shutter of the camera is open.  I want  to do this primarily for eye safety.  In addition, I'm curious as to whether I can then run the laser at a higher power level for this very short period of time.

The camera is gathering images at 60 FPS.  This means it is collecting an image every 16.6 ms.  The shutter time is adjustable between .12 and 512 ms.  In this case, let's say that the shutter is open for .3 ms.  I might keep the laser on for .1 ms on either side of the shuttering, just to ensure that the laser is at full brightness for the entirety of image capture.

So, I'm looking for a .5 ms pulse every 17 ms.  First of all, is  a diode laser (like this one) even capable of pulsing this quickly?  Also, could I run the laser at say, 50mW for that short period of time, given that I'm running it at a 3% duty cycle?

Lastly, any circuits capable of doing this would be awesome.

Thanks!


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I am reading and studying data sheet of the semiconductor 1N4001 until 1N4007, by Fairchild on onsemi.com. And I can't understand this parameter "forward surge current"

My main language isn't English, should be why I can't understand this concept!

Someone can give me an idea about this parameter/concept?


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I have the following relay: osa-ss-212dm3

I want to control my AC lamp which is connected directly to a 220V socket. By reading the datasheet, I found it says that its rated voltage is 240V AC and max switching voltage is 30V DC. Can I connect this relay safely into a 220V AC power socket and trigger it with 5V from my micro-controller?


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I am trying to use an IGBT module (dual IGBTs in common-emitter arrangement) as a static switch for 120VAC. I've done as much reading as I can, and I understand there are issues with losses and turn-on/off challenges. I am building 3 different switches using different devices and comparing losses, transient response, etc.

Here is my issue. I ended up burning the input (control) side of my gate driver. I think gate current went through it and destroyed it. High current (presumably) went out the VCC1 pin and into the microcontroller, destroying it as well. Everything else seems fine. The DC-DC converter appears unscathed, as does the IGBT and snubber.

I am not great at drawing schematics yet, so apologies for it being slightly messy. I am using a MGJ6 15V/10V DC-DC converter (https://www.mouser.com/datasheet/2/281/kdc_mgj6scdc-1019175.pdf) to power my gate driver, which is a 1EDC60I12AH (https://www.mouser.com/datasheet/2/196/Infineon-1EDCxxI12AH-DataSheet-v02_00-EN-1272149.pdf). 100nF decoupling caps on both modules and a 20μF bulk cap on each DC-DC output. 20R resistors on sink and source driver outputs. 1μF-47R snubber network. I tried following the recommended setup using a bipolar supply for the gate driver the datasheet recommended.

Have I made any foolish mistakes with my schematic or chosen components? Am I not grounding components properly? Is there some underlying isolation issue that isn't clear to me?


texts: Why is it that we are able to combine Amplitude and Phase modulation (Resulting in QAM) but are not able to do so with frequency? Why not combine all three degrees of freedom (Amplitude, Frequency, Phase) for modulation?


texts: In SMPS , why does peak current mode control have lower gain for inner loop compared to average current mode control?

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This has been bothering me for a while.

In some of the design notes of power management ICs , it is mentioned that peak current mode control has 'lower gain - wider bandwidth' inner loop compared to that of average current mode control. Why is it so?

Quote from a design note-

"Peak current mode control has a low gain, wide bandwidth current loop which generally makes it unsuitable for a high performance power factor corrector since there is a significant error between the program signal and the current."
Application note for UC3854 Power factor correction

Thanks


texts: Do AVR registers and ports need to be initialized to zero?

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During the initialization routine of my code I use to do such things as:

clr    r0  ; will always stay zero

and:

out    PORTA, r0; initialize ports
out    DDRA, r0
out    PORTB, r0
...

Is this actually necessary? Or can I be sure this is automatically done upon reset? Especially, can I rely on all ports to be set as inputs by default so there is no problem with external votages when no code is executed?


texts: Difference between If-else and Case statement in VHDL

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I want to understand how different constructs in VHDL code are synthesized in RTL.

Can anyone tell me the difference between If-Else construct and
Case statement constructs of a process in VHDL in terms of how the code is inferenced into RTL circuit by the synthesis tool ?
Do consider the case of multiple nested if-else and mixing
case-statements with if-else construct inside a process.
Also when to use which construct ?

PS: I have seen a related question "Multiple if statements in process in vhdl" but that doesn't answer my question in anyway.