texts: Analyzing a simple circuit with transistor

texts:
I've been trying to understand how to analyse circuits with transistors, but I'm having a hard time finding out where to start when confronted with the following two types of circuits. (Gain = infinity)

In the first circuit I've tried applying kirchhoff's laws to find out some currents and voltages but I got stuck finding the current flowing through the diode and the voltage Vce.

In the second circuit I simply can't start doing anything, I don't know what to do with the current source and how to start.

I don't want the solution, but some guidance(as where to start, how to approach these situations) would be really much appreciated.
I'm really sorry if this post asks some stupid questions.


texts: Find the frequency at which Vin gets to Vo without the phase shift

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Provided that \$R=10k\$ and \$C=10nF\$, find the frequency at which \$V_{in}\$ gets to \$V_o\$ without the phase shift.

EDIT: \$V_{in}\$ is a sinusoidal source.

So far I've concluded that it would happen for \$V_{in} = X\$, and if I use that I get that \$f\$ is equal to infinity. But I don't know how to get the minimal frequency (as a real number) at which we can safely assume that \$V_o = V_{in}\$. Hints?

Here's my work:
$$C\frac{d(V_{in}-X)}{dt}=\frac{Vo-V_{in}}{R}$$
$$V_o=V_{in}+CR\left(\frac{dV_{in}}{dt}-\frac{dX}{dt}\right)$$
Since the condition is \$V_0=V_{in}\$ then \$V_{in}=X\$.

Let's use \$C'=-1(j\omega C)^{-1}\$. Now we have
$$\frac{X-Y}{C'}=\frac{Y-0}{R} \quad \rightarrow \quad Y=\frac{R}{R+C'}X$$
and
$$\frac{V_{in}-X}{C'}=\frac{X-Y}{R} \quad \rightarrow \quad X=RV_{in}\left(C'+R-\frac{RC'}{R+C'}\right)^{-1}$$

Now using $$V_{in}=X$$
we have
$$C'+R-\frac{RC'}{R+C'}=R$$
hence
$$C'=0$$
$$f = \infty$$


texts: If I want to use a parallel port to control this 8 channel relay instead of Arduino, do I need to make any modifications?


texts: How to choose speaker impedance for a VERY specific application?

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Ok, so this may be a long post. I want to preface by saying I have very limited electrical engineering knowledge, so thank you in advance :-)
I'm working on a medical device for a college project. Because of COVID-19, we aren't able to actually prototype and test our device but we want to design it as best we can virtually. The device application requires that a constant sound source be sent up a nostril. The signal generated should be < 10 V pp, 7 kHz, 100 dB > (based off of a clinical study).
The study we based our values off of uses a 50 ohm speaker, but our device needs to be powered by a smartphone audio jack.
What impedance speaker can I use to accommodate the signal inputs? It's also important that the speaker is no bigger than 1-3 cm. Will we need an amplifier as well? Is this even possible?


texts: Problems with 12V rail on ATX Power supply conversion

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I am trying to convert an ATX power supply to a lab bench supply following this Instructable, but with one change: Since I only had one red plug on hand, I connected the +5V and +12V rails to a SPDT switch with the common lead then connected to the load resistor and the (1.5A fused) output:

The problem I am getting is that when the 12V rail is selected, the PSU turns off and does not supply power, i.e., neither the 5V or the 12V rails are "hot" and the fan spins down. When 5V is selected, it works fine (and both the 5V and 12V rails are "hot.").

Why is this happening?


texts: Why is this D flip flop not working in LTspice?

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Below is the circuit:

I expect the Q1 Output should follow the clock since the DATA is set to one(5V), but the output is zero:

I looked for many examples but couldn't figure out what is wrong.


texts: Needing help with chip identification: Hard mode

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I'm decently skilled with basic ic identification methods and lot number cross reference identification for the rebadged chips, but I've ran into a chip I just cannot identify. On the same board there are some chips I could only track down via lot number, so I'm sure this one won't be super simple. This product was made in China, possibly with anti-cloning in mind.

My leads so far: It appears to be the only micro controller on the device. It's driving a small oled display, a few gpio for interfacing, either has a few analog pins for current/voltage reading or it has an offboard chip I don't know about. The Logo looks like Gigadevice, but they don't even make a chip in the same package from what I could tell...


texts: Is there any program that I can use to find the transfer function of a filter?

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I need to find the transfer function of Sallen-Key second order notch filter.

Is there any program that can show the transfer function of s?


texts:
Edit: for some context

I'm working on an LTE project and was wondering if anyone more knowledgeable than I would be able to answer this question.  Given the first table, we can see the relationship between MCS (related to channel quality) and TBS (Transport Block Size) index, and Modulation order which isn't too important right now.  Looking at MCS 8 for example, we'll take the TBS index on the right of the first table, go to our second table, and than we can clearly see how many bits we can fit into a certain amount of Resource Blocks.  At MCS 8, we see 1 Resource Block (RB) can fit up to 120 bits, and 2 may fit up to 256.  This table is supposed to have some relationship such that:  If you halve the MCS and double the amount of resource blocks, you should have some equivalent amount of bits.

This means if your channel quality degrades to half (for example sake we'll keep it simple) all you must do is give each user one extra RB to satisfy whatever allocation they have.

A real example: starting at MCS 8, at 1 RB we have 120 bits.  If we drop to MCS 4 (half of 8) we will have to send twice as many RBs (two RBs), which we can confirm in the table as being 120 bits (equivalent to MCS 8 at 1 RB).

My question is why the heck is MCS 6, 1 RB 328 bits?  It doesn't make too much sense to me for a lower quality channel than MCS 7, 8, 9... to have more bits in the first RB.  Also this breaks the general trend that I just described.  Does anyone know why this is happening?  Also, how is it possible to have more bits in one resource block than two?  Are these imaginary bits that dissapear somehow?


texts:
I am trying to build an antenna to connect to the GOES-16 satellite (downlink at 1690,1MHz, linear polarization) with my SDR. My plans are using a 1m offset parabolic dish with a BiQuad feed, connected to a RG-58 coax line (50 Ohms) and followed by a filter (I have not decided yet wether to use a SAW filter or a end-coupled microstrip one)and a 20dB LNA. I live in a place where it will be difficult to get the signal from the satellite due to its low elevation and interfereces, so it is crucial for me to optimise the most the design.

Since the BiQuad is a type of dipole, I imagined that I would need a balun to improve the overall performance of the antenna. Assuming that the antenna is sufficiently well matched to the 50Ohm coaxline, only a 1:1 balun would be needed. However, most of the SMD baluns I find that handle this frequency carry an insertion loss of around 1-3dB with them. Hence, my questions:

Is it still worth adding the balun in spite of the big insertion loss? Would the losses/noise of the receptor without the balun be more inportant that those 1-2dB? Do homemade baluns (5-6 turns of coax cable) also have this insertion loss?

Thank you in advantage.

Edit: changed values of insertion loss to more common ones


texts:
Im a very beginner to electronics. Im trying to build a simple circuit with push on off latch button. Means if we push the switch first the led should on, again push it should off.
So when in search I got a circuit as shown below. But its little different from my requirement. My requirement is like there are 5 switches. When ever a switch presses the corresponding led should toggle. Also the worry is  if we hold the switch to the on state for some seconds, does it toggles quickly. if so how can we avoid that. Like even if we hold the switch it only should toggle one time

So if first switch presses, it should turn its corresponding led if the led is off. Same way when the second, second led should on (if its off). 3rd 4th 5th are same. So when 1st again press the first led should go off. Requesting kind help.
Also a very dump question. In circuits there is marked ground?? So if a battery power circuit, what is mean by ground???


texts: Schematic review - Darlington transistor seems to stay saturated in rare cases

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This question is related to a circuit that was designed about 5 or 6 years ago. We observed some failures over the years, where the resistor R25 gets very hot (beyond 120°C).

I was not involved in the design back at the time and are somewhat unsure/skeptical about the circuit function and how to debug the issue.

Background:

The schematic is part of the physical bus layer implementation of a M-Bus Master device. The relevant information (to this question) from that link is:

  The transfer of bits from master to slave is accomplished by means of voltage level shifts. A logical "1" (Mark) corresponds to a nominal voltage of +36 V at the output of the bus driver (repeater), which is a part of the master; when a logical "0" (Space) is sent, the repeater reduces the bus voltage by 12 V to a nominal +24 V at its output.

Basic functional description (refer to schematic):

(Correct me if something seems to make no sense. As I mentioned I did not design the circuit and interpret it the way I think it works.)

The voltage on MBUSOUT is toggled between 24V and 36V synchronously to the TXD1 signal that comes from a micro controller USART
The "trick" to toggle the voltage levels between 24/36V are the z-diodes D3 and D4. Those diodes offset the voltage reference of the regulator IC5 (6V output) by either 18V (Q4 is off) or 30V (Q4 is on).
The function of Q5 is (as far as I assume, its not properly documented :/) to speed up the edge transitions (36V->24V) by discharging the parasitic bus capacitance (bus can be several hundred meter long) through R25.
D5 prevents Q5 from switching when the bus is idle.
Q5 switches on when bus voltage changes from 36V->24V because Vbe(36V-24V-5.6V )

Issue / questions:

In rare cases, R25 gets very hot, so Q5 obviously does not switch off.
We suspect the problem is related to temperature (Q5? D5? IC5?). Probably thermal runaway?
I believe it may be a problem with an unstable operating point of Q5?
Shouldn't the current through Q5 be limited by a base resistor?

Any feedback and suggestions for improvements are welcome.


texts: Building a solar phone charger, how does a solar panel charge batteries and what voltage should the panel and the batteries be?

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I am new to electronics, please don't mind mistakes
Right now i have a 5v solar panel, and a 3.7v battery,and i plan on buying step up converter from 0-9-5v to 5v. I have an iphone 6 with the new lightning usb, and i read that you need a special usb step up converter that also provides something to the data pins on the usb. i'm also not sure how a 5v solar panel should charge a 3.7v battery.
Also, an iphone needs 1.2A i think, and i dont know how to check what amperage my solarcell/batteries/converter have.

battery: https://www.123accu.nl/123accu-18650-batterij-1-stuk-3-7V-2600mAh-i26531.html but with 2000mAh instead of 2600

i could use a battery pack with rechargeable aa's, but those don't hold a lot of power and i don't own any. But if i bought some, how does it work with solar panel voltage charging the combined battery voltage?

EDIT: fixed battery link


texts:
I'm trying to build a circuit that uses an ATMega48 PDIP-style chip and an ATTiny26. I'm stuck on loading code onto the ATMega48 using an Arduino Uno.

I've been following these instructions. I got all the way to step 4 when I got this error:

>avrdude -P COM3 -b 19200 -c avrisp -p m48 -n

[...]

avrdude: Device signature = 0x1e920a
avrdude: Expected signature for ATMEGA48 is 1E 92 05
         Double-check chip, or use -F to override this check.

[...]

I did the easy thing and added the -F option, and everything seemed to work out. Then I added the hexfile (following the format specified in the guide) and got this:

>avrdude -P COM3 -b 19200 -c avrisp -p m328p -u -U flash:
w:"[...]\build2681525234531849420.tmp\Blink.cpp.hex":i -F

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.07s

avrdude: Device signature = 0x1e920a
avrdude: Expected signature for ATMEGA328P is 1E 95 0F
avrdude: NOTE: FLASH memory has been specified, an erase cycle will be performed

         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "[...]\build2681525234531849420.tmp\Blink.cpp.hex"
avrdude: writing flash (1084 bytes):

Writing | ################################################## | 100% 1.34s

avrdude: 1084 bytes of flash written
avrdude: verifying flash memory against [...]\build2681525234531849420.tmp\Blink.cpp.hex:
avrdude: load data flash data from input file [...]\build2681525234531849420.tmp\Blink.cpp.hex:
avrdude: input file [...]\build2681525234531849420.tmp\Blink.cpp.hex contains 1084 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 0.98s

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0002
         0x61 != 0x01
avrdude: verification error; content mismatch

avrdude done.  Thank you.

How do I go about fixing this?

For the record, I'm using the "minimal" configuration specified here:

Arduino -> Mega48

10 -> 1

11 -> 17

12 -> 18

13 -> 19


texts: 12 V pulses with 100 MHz repetition rate

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I have to control an high impedance load (> 25 MΩ) with 12 V pulses with maximum 5 ns of width and a repetition rate of 100 MHz.
I can generate the pulses with the required shape using an FPGA but I can only reach 2.2 V.
I was thinking of using a fast RF NPN bjt such as the NXP BFU530 or the Infineon BFR92P.

I have simulated the circuit in Ltspice and I get the following results:

How can I reduce the recover time of the switching without further decreasing R2? (i am already almost at the limit of the IC.)

Or do you have an alternative circuit to suggest?


texts: Choosing Resistors for Brightness in Parallel LED Array

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These LED’s I have are incredibly bright. So when using just one, I would typically use a 10-15k resistor in series to dim them down. Now I need to use those same LED’s in a parallel array. I used an LED array calculator to compile a circuit. The values I put through were taken from the data sheets. 20mA is the forward current, but that would be way too bright. The calculator chose 100 Ohm

In order to maintain roughly the same brightness per LED as in a series circuit with a 10-15k resistor, how do I calculate the new resistors? Should I simply use the same resistor values?

!


texts: Emulating the start/stop button on the remote control of the iPhone

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I need to build an (apparently) extremely simple device which is basically a pushbutton that pauses and restarts the playback on an iPhone.

This is exactly what the central button does, on the remote control that can be found along the cable of iPhone headsets - both the official Apple ones, delivered with the iPhone, or commercially available compatibles.

I've spent the past half hour researching around (including this site) to no avail. As I am writing this, I am at the office, without any instrumentation, so I cannot probe the TRRS 3.5 mm jack connector to see what happens as I press buttons.

Just to make it perfectly clear why I need this: I need to build a pedal control for the pause/play function of any audio app. Let's say I've given a half-improvised lecture, which I have recorded on my iPhone, then I want to replay it and transcribe it. As a ten-fingered typist I type fast enough, but not so fast as to keep up pace with speech, so I want to pause and restart playback without lifting my hands from the keyboard.

This is a function which existed on good ol' Dictaphones, including - if I remember correctly - the very first one, invented by A.G.Bell in the 1880s, but apparently I cannot find a way to do the same with an iPhone.


texts: What is the True Pinout and Function of the 74ls181 in both of its modes (Active High and Active Low)?

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I've found several datasheets for the 74ls181 with pinout and function diagrams as pictured below.

This from Jameco (where I bought mine): https://www.jameco.com/Jameco/Products/ProdDS/46973.pdf

This one as the first google search result: http://www.esi.uclm.es/www/isanchez/apuntes/ci/74181.pdf

These do not at all agree with each other. What happens to P and G when switching modes? What happens to the outputs when switching modes? Do they invert or not? How does one go about sorting out this mess?


texts: reducing the voltage clamped by a TVS diode for SPI bus

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I'm making a board with an AVR. Between the MCU and the connector I would have multiple lines for SPI communication. Since the environment of this board is expected to be very dry, it is needed to protect the MCU pins from ESD events.
My solution is to use a combination of a ferrite bead, a series resistor and TVS diodes as shown in the image below. But this solution cannot reduce the clamp voltage which can be 10V~30V depending on the TVS diodes. If the I/O pin was an open-drain with a large pull-up resistor, then one can place a series resistor behind the TVS diodes. But I'm not sure what I could do for SPI lines. Is there a simple way to reduce the clamped voltage? Or is there any suggestions to protect the line better?

Would it be better to use an array of TVS diodes (or an IC that contains them)?

I don't want to use Zenor diodes, unless they are better than TVS diodes for ESD protection purpose.


texts:
I have to implement a rs232 receiver for my project. Does any one have any idea on how do I start learning / implementing this. Do i have to use the nios ii software or just implement it using verilog modules?

http://www.altera.com/education/univ/materials/boards/de2/unv-de2-board.html - The de2 board

http://www.altera.com/literature/ug/ug_embedded_ip.pdf Chapter 7 - UART core


texts:
I am simulating a BLDC model and one of the parameters I need to enter in my simulation is Viscose Damping (in units of [N.m.s]).
I am not familiar with this term, and after some research, I came across a formula that defines it as the ratio of a) the product of the constant torque and back emf constant, and b) the motor resistance. However, that was defined as viscose damping coefficient in units of [N.m/rad/s].

I did not find this value in the motor spec I'm trying to simulate.

My question is this:
1) what is viscose damping - in intuitive terms? What is it dependent on, and how does it affect the current consumed by the motor?
2) what is the difference between viscose damping and viscose damping coefficient and how are they different from each other (beyond the formula above). I assume that the difference in the units defined above is the presence of radians, but still need a clearer understanding.
3) If I know the viscose damping coefficient, how do I go to the viscose damping? Would a simple 2pi take care of the conversion, or is dependent on the rotational speed (omega) of the motor?
4) I also came across viscose damping torque when reading previous answers in this forum. How does the viscose damping torque differentiates itself from all the other 'viscose damping' terms mentioned above. What does it mean in terms of current drawn from the motor?

Thanks much!


texts: manipulating I/O ports of Intel 8255 PPI

texts: Can we use 8255A (programmable peripheral interface) as a 24 bit input or 24 bit output? we know there are 3 ports PORT A,B and C each of 8 bits. How they can be used as 24 bits I/O ports?


texts:
Ive been able to come up with the code below, trying to measure the voltages from three channels using the interrupt method. while the code runs without aby errors, im still unable to display anything on the lcd after having measured.
im no pro in avr stuff, just started a few months back.
any help is highly appreciated`

ISR(ADC_vect)                                   //selecting between multiple adc channels
{
    char buffer[10];
    uint8_t theLow = ADCL;
    uint16_t theTenBitResult = ADCH<<8 | theLow;

    switch(ADMUX)
    {
        case 0x20:
        //calculate temperature
        temperature = ((theTenBitResult) * 1024/5);
        _delay_ms(10);
        ADMUX = 0x21;
        break;

        case 0x21:
        //calculate and print voltage
        voltage  = ((theTenBitResult * 1024/5) * (1324675/324675));         //1M plus 300k voltage divider resistor values
        dtostrf(voltage, 5, 2, buffer);
        //sprintf(buffer, "%f", voltage);                           //as lcd library does not include int and float conversion to string is necessary
        lcd_gotoxy(11,0);
        lcd_puts(buffer);
        _delay_ms(10);
        ADMUX = 0x22;
        break;

        case 0x22:
        //calculate and print current
        current = ((theTenBitResult * 1024/5) * 1.5);                       //1.5 is the maximum current range expected
        lcd_gotoxy(11,1);
        sprintf(buffer, "%f", current);
        lcd_puts(buffer);
        _delay_ms(10);
        ADMUX = 0x20;
        break;

        default:
        //don,t expect any value here
        break;
    } ;
        ADCSRA |= 1<<ADSC;
}`


texts:
I wrote a program for a Cyclone II FPGA that divides 2 64 bit numbers and returns if the remainder is 0 using the modulus (%) operation.

When I compiled the program with 64 bit numbers for the divisor and dividend it used almost all of the logic cells in the device.

Is there a way to do division, or modulus, or [if modulus==0] in a way that uses less logic cells?


texts: When is using a π filter advantageous to a parallel capacitor filter?

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Below Vtr1 and Vtr2 are transformer secondaries with 12V amplitude at 50Hz:

Both circuits' bridges and loads are exactly the same except the ripple filters used. First one uses a "π filter", the other one only uses parallel capacitors.

As you can see from the plots the ripples are almost the same.

Why/in which situations one would prefer a "π filter" instead of capacitors?

edit:

Transient current at turn on is much much less in pi filter due to the inductor.

On the other hand, I vary the load resistance from 10k to 0 Ohm and it seems the pi filter is not a good idea for power supply ripple filtering for varying loads(?):


texts:
So , hopefully this is my last question on this system

it's about the connections:

about the transistor, i want to use it like a switch, so i wanted to know how to determine the value of the resistance needed before the base, i searched a bit and found this on resistance , IC, and transistors half way through the page there are some calculations, according to them i need about 250 ohms (if anyone wants to redo the calculations, the resistance of the relay is 400 ohms and max IC current is 20 mA), why did he use a 10K?
why did he wire the temperature sensors like this? can't we just wire them 1 pin ground 1 Vin and 1 Vout?
do we have to use resistors before the sensors? if yes how to determine it and how is this guy is not ? if no, why?
(note: i will be using a LM35 not LM335)
edit:according to this i will need to put a shield if i am going to connect the sensor away from the arduino , then i will need a cable and a shield
how is that going to affect the resistance need


texts: Voltage Reading On Voltage Regulator Heatsink

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While troubleshooting why an older LCD TV (Viewsonic N3751w) wouldn't turn on, I noticed several capacitors on the power board were swollen. Through my friend Google, I found that on this particular power supply (FSP271-5F01), it was common for the capacitors to go bad. I found a replacement kit, ordered it, and replaced the bad capacitors. However, the TV still did not turn on.

Now here is the part I need help with, and I'm hoping this is the correct forum to ask the question in. While troubleshooting further, with the TV  plugged in, I touched the voltage regulator heat-sink to see if there was heat being produced, and received a shock. Not a minor one, but a pretty decent, better than a shot of espresso type shock. I happened to be touching the metal frame at the same time.

I measured the voltage at 86v AC +/-. I measured the voltage in AC because the shock had the back and forth feel of an AC shock, versus the continuous muscle spasm of a DC shock. I am fairly certain there shouldn't be this kind of voltage present here, but as I only have a limited knowledge of circuit boards, was wondering if this is normal, and if not, where should I be looking for the bad component?

Included is a picture I downloaded of the power supply. The red ovals indicate the areas where I get the voltage readings. There is a cover that connects the two heat-sinks.


texts: Adding Currrnet limiting capability to parraled LM2596 ICs

texts:
I have see this instruction about hacking one ordinary boost/buck converter by adding the current sensing to its FB pin (feedback pin) like this schematic:

and know this system using for current controlling:

so my question is that what would happen if use the output of above current sensor as said at the  two or some many LM2596 module based like this ( these Buck converter are so low cost and if could be parallel could give more current and ...) like below picture ?

Update: I thought if I simulated this situation, in some software like EASYEDA (SPICE SIMULATION OPTION ON IT) could it be useful for this question!?

Thanks.


texts: Send or share DI data through network advice

texts:
i want to collect some data(DIs from some relays) and send them or use them in a network and finally put them in a DataBase like SQL, and i want it to work 24/7.
after searching i found some solutions like using Raspberry pi with network socket . but i think its kind of too much for this work, also not sure if it can work 24/7.
if any one know any other modules or easier solutions that can do this , i would appreciate it to introduce.
i know there are Arduino modules too, but not sure how difficult it is to get data from it through TCP-IP network. or about working 24/7.
thanks in advance .


texts: Pi Zero / GPIO Pins / +12V Power and Sharing Ground

texts:
I need a sanity check on my schematics before I pay for JLCPCB to make my PCB board.
Goal: To have my Pi Zero fire a pyro charge in a model rocket.
Setup: GPIO-20 Sends a signal to the MOSFET Gate, which then allows 12v of current to fire the pyro charge. The Ground (Negative) of the 12v battery and Ground Pin of the Pi are being shared.
Question: Does this setup look correct? Does anybody see any issues with the Pi sharing ground with the 12v battery? I built this out and tested this wiring with a breadboard using an LED to visually confirm this and a multimeter to see the voltage rise and fall as I enable/disable a signal from the GPIO pin. But as we all know, what works in testing doesn't always pan out in production. So I'm asking for a second set of eyes to double check me.
NOTES:

GND: Ground (Shared by Pi GND Pin & External Battery Negative
Terminal)
BATT+: 12v
GPIO20: Signal to Pyro 1
GPIO21: Signal to Pyro 2 (Not shown)
R8: 1 Ohm Resistor
R2: 470 Ohm Resistor
Q2: N-channel power MOSFET - 30V / 60A ->
https://www.adafruit.com/product/355
P2: Screw Terminal to Pyro Charge
P3: Screw Terminal to 12v External Battery
5v: 5v from Pi to power sensors
SCL: SCL to sensors
SDA: SDA to sensors

Thanks,


texts: neural network to simplify induction motor control

texts:
I will be working this summer on a paper about applying AI algorithms in control theory, i think induction motor control is a very interesting topic and i have found some papers about applying indirect field oriented control using neural networks but they are quite old  (late nineties)

The question is :

1-Is there any need to have a better method to control IM rather than FOC? Or simply what are the problems in controlling an induction motor?

2-another topic i found interesting, Is it important to have a POSITION control for an induction motor? I mean like we need to have large expensive steppers or servos to have accurate position control...Would it be better if IM can serve in such a field?

and thanks :)


texts: Why some through-hole component leads are ferromagnetic?

texts:
I was surprised when saw a magnet picking some random 0.125 W resistors leads. I was always thinking that leads are made of copper alloy. Are there some subtle reasons to make them using metals other than tin plated copper or copper alloys ?

Thank you


texts: Amplify current and voltage to preserve battery

texts:
I'm wondering, is it possible to provide for example 5V/500mA from a single 1.2V battery and consuming only 50mAh from the battery by using a low input voltage boost converter and a power amplifier ? (L272 and a TPS61200 for example)

I found that it's possile to go from 1.2v to 5v with the TPS61200 and go from 50mA to 500mA with the L272 but what if they're used together ? Will it preserve my battery lifespan ?


texts: so i'm trying to design a CPU and in all my previous designs i have used a cascade adder but i want to try using a fast adder to speed things up. when i search for "8 bit fast adders" all i get is the 4 bit fast adder designs and i don't want to link all the carry ins and outs together so does anyone have a true 8 bit fast adder design. all i want is the diagram, which means only the logic gates(and gate, or gate, etc) no blocks or anything like that. for an 8 bit adder with fast carry no other operations just adding.


texts:
This is going to start out like the other 53 pages of power supply questions "I'm a student working on a capstone project making an SMPS....". I have 12 months before the final design is due.

I'm thinking of purchasing some software to use at home for the designing of the PCB. The cheapest solution I can think of is Eagle for the eventual complexity I'll have (powering a ~150w load).

Now for the software addons. I was wondering how necessary are SI (Signal Integrity) tools for SMPS designs? I haven't decided on the topology yet, but I know the switcher and controls could generate high frequency signals so it seems pertinent. Now the package for Eagle also seems like the cheapest SI tool, FSPICE at $1k. Now I wouldn't' mind avoiding dropping 1k on this software but if it's unavoidable then its understandable, with a certain amount but not all being reimbursable.

Background: Pertinent to SMPS design: Course on Transmission Lines, Course on intro to Power Electronics, standard EE course on Intro to Power Systems, Course on Linear Control Theory and Discrete Time Controls. Otherwise standard courses an EE senior would have.

Is the investment worth it?

Edit: I should mention I only brought up the layout and EMI issues because of this: http://ecee.colorado.edu/~ecen5797/course_material/layout.pdf


texts:
Let bits 0 and 1 be equi probable. For bit 0, any value between -0.3 V and 0.3 V can be taken
with equal probability. Similarly for bit 1, any value between 0 V and 1 V can be taken with
equal probability. If threshold is 0.25 V i.e. bit 1 is detected if received voltage is greater
than 0.25 V and bit 0 is detected otherwise, then find the probability of error of this system.


texts: 8-bit shift register 74LS164 not working

texts:
I am trying to use an SN74LS164 8-bit serial-to-parallel shift register with my Raspberry Pi, but I have some problems.

I connected:

VCC, A, B and CLR to +5V
GND to 0V
CLK to Raspberry Pi GPIO

simulate this circuit – Schematic created using CircuitLab

When I power-on the circuit, all the LEDs are off. Then I send a clock pulse from the Raspberry Pi (go high for 100ms then go low). However instead of having the just first output (QA) go high, the first 3 or 4 outputs go high (QA, QB, QC and QD).

What am I doing wrong?

I took some photos of the scope, the first is the clock from the GPIO (without nothing) and the second is the clock connected to the register.

-- EDIT --

I added capacitors and MOSFETs to respect max output current. I re-added pull-down resitor on clock line because of the natural +1V offset (this offset come from the register not the pi)


texts: For pre and post electrical testing of burn in components under test: what is the best way to measure current and voltage through said burn in components before and after burn in to verify if the components are still in range of its parameters on its data sheet. Basically making sure the component is still in operational condition. I need some type of a circuit to test current and voltage on these components. These components are SMC and D^2 Diodes that are placed into a socket during the burn in process. These components will be on a PCB and put into an oven. Thanks


texts: What's the difference between 74LVC1G74 and 74LVC2G74, finally?

texts:
I always thought that number before G in the part number is a number of identical gates in the chip. 1G08 is one AND gate, 2G08 is two AND gates in one package. Simple and understandable.

I am going to use LVC74 in my design, and was astonished to find out that 2G74 has one D-type flip flop in it. Fortunately, I did not buy it yet being totally ensured that it must have two DFFs in SSOP-8 package - 2 power pins, one data pin, one clock pin, and one output pin per trigger (no set, no clear, no inverted output).

I see this question on TI forum, and in my opinion answer is not clear, and seems to be wrong. I have compared 1G74 and 2G74 datasheets from Nexperia, and they appear the same with difference in document formatting.

WTF?


texts: What is this M01PTH I see referenced on schematics?

texts:
What is this part "M01PTH"?

I'm interested in building this "BBQ Temp Controller" Arduino-based project here:
http://hruska.us/tempmon/

One component involved is a 12v blower.  In looking at the schematic for the above link, I see that the positive for the blower is connected to something that says "M01PTH" above the designation "12V".  I cannot find any parts online that correspond to "M01PTH".

I see the same reference to "M01PTH" on a couple other schematics for power supply stuff as well, for example here:
http://www.schmalzhaus.com/UBW32/EE/v26/UBW32_MX795_v26_sch.pdf
and here:
http://www.instructables.com/id/Practical-DACs/step4/Build-It/

but I have no idea what this is.

Does anyone know what this is or means?


texts: Higher voltage battery able to drive load longer at stable voltage?

texts: If I've got two batteries of the same capacity, one is 12V and the other is, say, 18V with a step down buck converter, will I essentially be able to power my load at 12V for longer? I know that a battery's voltage will decrease as it discharges, so it seems to me that a better way to power a load with a more stable voltage (and maybe for a longer period of time at this voltage) would be to power it with a higher voltage battery and step that voltage down. Is this true?


texts: In logic levels, why are the driver and receiver depicted as inverters?

texts:
In Digital Design and Computer Architecture (Harris and Harris), the following schematic is given , in discussing logic levels.

Why are the driver and receiver depicted as inverters?


texts: Why is a current signal preferred to a voltage signal for long analog transmission?

texts:
Some sensors act like current sources, and I have seen it several times, especially for very long wires even at outdoors like wind vanes. 4-20 mA current loops are used instead of 0-10 V voltage for instance.

What can be the physical explanation for this? How is current more advantageous?

(I'm also wondering in terms of EMI interference whether a current loop signal is more immune and why.)

Please explain this concept by using circuit diagrams, voltage current sources with some components. How common mode interference is coupled in both cases, etc. and why a current loop is immune to noise.

EDIT:

After reading the answers, here is what I understand(click to see the simulation diagrams and corresponding plots):

I apply common mode Vcm interference in all scenarios.

In the first top figure a current source with 1Giga Ohm impedance is transmitted via an unbalanced/inbalanced cable and even the receiver is single ended the output is immune to noise. (1G Ohm makes the noise small, the lesser this Rcur the more the noise at receiver)

In the middle figure a voltage source is transmitted via an unbalanced cable and the receiver is single ended, the output is very noisy.

In the bottom figure a voltage source is transmitted via a balanced cable and the receiver is differential-ended, and common mode noise is eliminated.

Is my conclusion/simulation correct to represent this question?


texts: Methods to drive a multiplexed LCD with logic-level signals?

texts:
I've used such a technique in a couple of the products I've designed, but I've never seen anyone else do so.  It's possible to drive a 3-way multiplexed LCD using a bunch of 74HC595's to generate an 8-way pattern that gives each "on" segment an RMS excitation of 0.866VDD, and each "off" segment an RMS excitation of 0.5VDD, an RMS excitation ratio of 1.73:1.  By comparison, driving a conventional display with 1/2 bias (requiring that idle rows be driven to half-rail, but active rows and all columns be driven to the rails) yields an RMS "on" voltage of .707VDD and an "off" voltage of 0.408VDD--the same 1.73:1 drive ratio.  Using a 1/3 bias would result in a somewhat better drive ratio, but require all row and column drivers to support four output voltage levels.

How have you used purely logic-level signals to drive a multiplexed LCD?


texts: What is the total circuit impedance of a parallel LC (6.8mH and 0.1uF) in series with a 1.2kOhm resistor, at 2.5kHz?

texts:
This is not homework and I've really tried to get an answer, unfortunately, I can't seem to understand what's going on.

Basically, I tried to do the impedance of \$LC\$ (so, \$z=[(\omega C)-1/\omega L]^{-1}\$. Then I tried to get the impedance for the resistor, but I got stuck. After looking online, I tried to do \$1/C \times (\omega/[\omega-(1/\sqrt{LC})]^2\$ because I found it somewhere. Again, no idea what to do with the \$R\$.


texts: I need to compare planar MOS transistor and FinFET for a project. But there is no inbuilt symbol for FinFET in LTspice IV. Can anyone help me with this?


texts: Can I run this hard drive on 12Vdc 1.25A instead of 1.5?

texts: I have a My Book Essential external hard-drive from WD that ships with a 12Vdc 1.5A 18 Watt adapter. Will I be risking everything by plugging it into a 12Vdc 1.25A adapter?


texts: Identifying an unknown code "W62" SOT363 dual inverter

texts:
QUESTION: What is this component?
RESOLUTION: Equivalent part is SN74LVC2GU04DCKT normally code "CDK" This appears to be specially "Wacom" branded for obscurity. Question below for historical context.

I have a component from a Wacom DTK-2100 digitizer board that I'm struggling to identify. It is presently situated in a fully functional board.

Some context information, Top middle pin is 5V, bottom middle pin is 0V
The top right and bottom left pins have no resistance between them, in a functional circuit, the Top left had 2.86V, and the bottom right had 2.2V, the Bottom Left/Top Right had 1.75V.

Any suggestions on what I could try replacing this with in the event that it cannot be identified? Looking up the short code brings be to an SOT323 package, and 3 pins simply won't do.

For more context here is a scan of the board from someone else. This component is in the Bottom Right quadrant between the horizontal quartz crystal and the WACOM QFP component. It is marked U50 on the PCB.

Current presumption: I took a look at a same generation model and the component was a "CDK" dual inverter as anticipated by one of the commenters. Link to datasheet: http://www.ti.com/lit/ds/symlink/sn74lvc2gu04.pdf

I included a more complete schematic of the circuit now that I'm reasonably sure of what it is and knowledgeable of the neighboring components. It appears Wacom rebranded the device to obscure its function in higher end models.

(Side note, for those attempting digitizer repair on DTK-2100 boards, if there is no -4V line, in the center of the board (should have +5V +4V and -4V rails mid board, and +5, +5 and +3.3 rails along the edge of the board) then most likely this component is the defective culprit as the clock is needed to generate an inverting signal.)


texts: Can I use low voltage but higher maximum amperage?

texts:
I have an electronic device (electromagnet solenoid) that working on 9V/DC and 30mA current (9*30=270mW)

Question 1: If there is a 5V/DC adapter that could produce maximum 54mA (5*54=270mW), could I use it to power that solenoid?

Question 2: Does the high voltage low current is same as low voltage high current , alhough they produce the same Watt?


texts: What's a opened solder bridge signifies?

texts: I'm new to STM32. Recently I'm trying to understand the schematic of it. I came across the term "soldering bridge" default: open. Does it signifies that the two pins are opened (which means not connected) or it means two of the pins are shorted?


texts: How do I slightly change amplitude of the 230 VAC loaded power line?

texts:
Let's say there is 230 VAC power line. How can I convert it to let's say 223 VAC? Expected current is up to tens of Amps.

I could do one the fllowing:

Use 10 bidirectional diodes to convert these 7 extra volts to a heat. This is the most simple but not efficient and can be a tricky thing for big currents.
Use a autotransformer. As I understand most of the windings can be done with a thin wire. The winding which will take all current will have relatively small amount of turns. This is much more efficient than p.1 but the transformer will be a big piece of steel and copper = big and expensive.
Use SMPS. But I can not figure out the best topology for this type of implementation. In simple this should look like this:

SMPS solution looks most promising for its efficiency but it is a bit tricky for me.

Could you please put some comments on the SPMS part? Or probably I missed something else worth considering?

UPDATE 1

I just tried one idea and at least simulation looks pretty good:

This schematic will need a feed-back as the voltage difference depends on a load resistance. Moreover I will need to switch the switches simultaneously and to deal with switching bad processes but anyway this looks very promising. Is there any drawbacks I did not aware of?


texts:
I'm trying to design an EMI filter for a 3-phase induction motor driver. I've looked at some example filter designs but in one of them I couldn't understand the capacitors and resistors what they are stands for?

There are 4 X-Y caps at the beginning and at the end, 1 common mode choke and DC bulk capacitors. Can you explain why the series resistors and other capacitors are used? I circled them in the picture.

Thank you.


texts: What is the reason to put two MOSFETs in a series connection?

texts:
background first:
I am currently trying to repair my old Pioneer amplifier (A-405R). The error description behaviour is a sporadic infinite triggering of the relay (marked blue one in the schematics).
In the working case, V_G = 4.8 V. In the not working case it is below 4 V.
What I am really wondering (due to lack of HW experience): Why are these two MOSFETs (2SK1132: Datasheet MOSFET) in series? So I thought the benefit of that MOSFET is to switch the relay on and off. Why do you need to then there?

EDIT: See here for the more detailed schematic. Complete datasheet of the amplifier can be found under: Datasheet Amplifier


texts: Use a switch to override Arduino program

texts:
I am building a system where I am controlling 2 LED strips using an Arduino Uno, time chip and relay.
I have managed to get the lights to turn on and off on 2 separate days at different times.
Now I want to add a switch to override the program, turning the lights on, when they are not programmed to.
I would also like to add an LED to show when the switch is active.

Here is my code.

#include <DS3231.h>

int Relay = 4;
String today ;

DS3231  rtc(SDA, SCL);
Time t;

void setup() {
  Serial.begin(9600);
  rtc.begin();
  pinMode(Relay, OUTPUT);
  digitalWrite(Relay, LOW);
  delay (2000);
}

void loop() {

  today = rtc.getDOWStr();

  if (today == "Thursday") {

    if ( 15 > t.hour && t.hour < 22) {
      digitalWrite (Relay, HIGH);
    }

    else{
      digitalWrite (Relay, LOW);
    }
  }

  if (today == "Friday") {

    if ( 16 > t.hour && t.hour < 23) {

      digitalWrite (Relay, HIGH);
    }
     else{

      digitalWrite (Relay, LOW);
    }
}

}

How am I best proceeding?


texts: How do I calculate how fast a capacitor will discharge?

texts: Say I have a 1F capacitor that is charged up to 5V. Then say I connect the cap to a circuit that draws 10 mA of current when operating between 3 and 5 V. What equation would I use to calculate the voltage across the capacitor, with respect to time, as it is discharging and powering the circuit?


texts: I need to use one of those for an experiment (a solenoid with the shape of a torus). Unfortunately, as you can see, I don't know the appropriate name for it. I have built myself a temporary one but I'd much rather buy an industrial-made one to be certain about it's efficiency, and for that I need the name. Here is a picture of one that I made:


texts: Why are hardware inverters so prevalent?

texts:
I'm working on a flight control system that uses SBUS (a serial protocol), and the slave transmits inverted, so I had to invert it with a hardware inverter.

This isn't that big of a deal, but I'm curious as to why it can't just be done in software? This seems to be the case a lot of the time, that serial lines need to be inverted. Can't the receiving end just logical not every bit?


texts:
I'm interfacing an SPI chip with a PIC18 device, programmed with a C program compiled with the XC8 compiler, using libraries from plib.h. In the docs, I read:

void OpenSPI( unsigned char sync_mode,
              unsigned char bus_mode,
              unsigned char smp_phase);

  smp_phase
  One of the following values, defined in spi.h:
  SMPEND: Input data sample at end of data out
  SMPMID: Input data sample at middle of data out

What does this parameter change?

I'm interfacing the ENC28J60, and found out that both values for smp_phase result in a working connection. Are there chips that wouldn't work with both values, and if not, what's the use of the setting?


texts: gSpice: 'model is not a mosfet' error message

texts:
I'm trying to simulate a circuit. So:

I run netlist on the .sch file. It completed successfully.
I've opened the .net file with gSpiceUI and tried to simulate, but an error was given:

  M1: model  is not a mosfet

The netlist file:

**************************************************************
*  Electronic circuit simulation file generated by gSpiceUI  *
*             Version 0.9.98 Alpha (14/10/2009)              *
**************************************************************

* Component Definitions
C1 1 2 100nF
CLoad 0 5 100uF
DOff 0 1 1N4007
DOn 1 3 1N4007
L1 3 2 22uH
M1 2 4 5 DMP2004WK
RLoad 0 5 1M
V1 5 3 DC 5V
* Signal source (V2 4 3 pulse 0 5 10n 10n 100n 1u 2u)
V2 4 3 GENERATOR(1)

* Model Definitions
.MODEL 1N4007 D(IS=76.9p RS=42.0m BV=1.00k IBV=5.00u CJO=26.5p  M=0.333 N=1.45 TT=4.32u)
.MODEL DMP2004WK PMOS( LEVEL=1 VTO=-1.00 KP=0.200  GAMMA=1.24
+ PHI=.75  LAMBDA=208u RD=0.126 RS=0.126
+ IS=200f  PB=0.800 MJ=0.460 CBD=40.6p
+ CBS=48.7p  CGSO=240n CGDO=200n CGBO=1.31u  )

* GNU-Cap Simulation Commands
.OPTIONS NOPAGE
.PRINT TR V(RLoad)
.GENERATOR AMP=5.00 OFFSET=0.00 FREQ=1.00K PHASE=0.00 INIT=0.00 MIN=0.00 MAX=5.00 DELAY=0.00 RISE=0.00 WIDTH=5.00u FALL=0.00 PERIOD=1.00m
.TR 0.00m 10.00 50.00u TE 27.00 BASIC

.END

Do you know why this error appears how to make this working?

If any additional information is required plz ask, cuz I'm not sure if there's additional info I need to supply.

Thank you.


texts:
Where can one go to find SPICE models? I am curious if there is a giant repository out there somewhere that I can search?

In particular, I am looking for a model for an LM317 voltage regulator, at the moment. However, I can't find this on Linear's site and I am not having much luck with the other manufacturers for their parts. It seems like this would be a very common problem for designers wishing to simulate their circuits?

Thanks!


texts: I recently purchased a Dc pump rated 3 to 6v~ On connectig it with a 9v battery(cheap one) it works well for 5~~minutes continuous after which its performance degrades to a level of it where it's useless I don't understand is there a fault with my 9v battery or the pump,, I did check the voltage of my battery after 5 minutes it gave me a reading close to 7.8 but my pump barely worked


texts: When does an electrical product get an RU (Underwriters Laboratories) certified mark?

texts:
If you take an example of contactor, it can be used in residential, industrial, electric vehicle applications etc.
Let's say the contactor has passed the UL standards corresponding to the industrial and residential applications.
Can it get the UL certified mark or does it have to pass all the standards corresponding to all its applications to get the mark on its product?


texts: Maximum output and efficiency for a simple transistor based amplifier circuit

texts:
1. Question

What is the maximum output over  \$R_L\$ and the maximum efficiency \$\eta\$ for the amplifier circuit shown below:

Below you will find my solution. Is this done correctly? What would you have done differently?

2. Voltage over \$R_L\$

Assumed is an ideal transistor with infinite current amplification \$\beta\$ and saturation voltage \$U_{ CE_{ sat } }\$ to be 0. Therefor the base current is 0 and the voltage drop over the transistor is considered constant for the whole output range.
Furthermore is the output voltage \$u_a\$ sinusoidal.

This means for $$u_a(t)=\hat{U}_a\sin(\omega t)$$ the amplitude \$\hat{U}_a\$ is the voltage divider over \$R_L\$, when the maximum of the dynamic range of the transistor is reached, that no current flows over the transistor.

$$U_{a,\,max}=U_0\frac{R_L}{R_L+R_C}$$
$$\hat{U}_{a,\,max}=\frac{U_{a,\,max}}{2}$$
$$U_{a,\,eff,\,max}=\frac{\hat{U}_{a,\,max}}{\sqrt{2}}$$

The root mean square leads to:

$$U_{a,\,eff,\,max}=\frac{U_0}{2\sqrt{2}}\frac{R_L}{R_L+R_C}$$

3. Maximum output \$P_L\$ over \$R_L\$

$$P_L=\frac{1}{2}\frac{U_{a,\,eff,\,max}^2}{R_L}$$
$$P_L=\frac{U_0^2}{16}\frac{R_L}{(R_L+R_C)^2}$$

For \$\frac{dP_L}{dR_L}=0\$ leads \$R_L=R_C\$ to the maximum output over \$R_L\$.

$$P_{L,\,max}=\frac{1}{64}\frac{U_0^2}{R_L}$$

4. Maximum efficiency \$\eta\$

The total circuit power is the voltage over both resistors which is \$U_0\$:

$$P_{in}=\frac{1}{2}\frac{U_0^2}{R_L+R_C}$$

With the given condition that \$R_L=R_C\$:
$$P_{in}=\frac{1}{4}\frac{U_0^2}{R_L}$$

The maximum efficiency \$\eta\$ is:
$$\eta=\frac{P_L}{P_{in}}=\frac{1}{16}=6.25\%$$


texts: Using Character Match functionality in a STM32F7 chip

texts:
I'm trying to implement a UART receiver that works by finding a '\0' in the datastream, OR when it receives 256 characters at which point the data should be processed by an interrupt. The point is to use DMA for reception but if either of these events occur it should stop filling up the current buffer and process the data. The reason is that I'm using COBS encoding to frame my data.

The STM32F7 chip has something called Character match as part of the Modbus specification, which I got working by setting the bits in the configuration register since it's not supported by the HAL(stm32cubemx, which would remove this code upon regenerating) libraries:

MODIFY_REG(huart->Instance->CR1, UART_CR1_FIELDS, tmpreg | USART_CR1_CMIE);

And at the end of the UART interrupt handler I do

UART8->ICR |= USART_ISR_CMF;

To clear the character match interrupt flag so it won't run again.

As I understand it the interrupt handlers in the STM32f7xx_it.c are in fact the first functions

void DMA1_Stream6_IRQHandler(void) and void UART8_IRQHandler(void)

in my case that are run as interrupts occur in a peripheral, and from these functions a handler(HAL_xxx_IRQHandler()) is run that check what interrupt occurred and run any user defined functions depending on the interrupt flags, like for example:

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *UartHandle) {
    //process data, this runs when DMA finishes receiving bytes
}

The problem is that it's not clear which one of the interrupt function is ran when for example I'm using DMA and I have received my specified amount of data over UART. Does it run the UART interrupt or the DMA stream interrupt? How can I reliably end up in the same callback function on '\0'(uart?) or 256 bytes(dma?) to process my data without botching the interrupts?


texts:
Firstly some background:

I would like to make a magnetic stirrer, like the ones they use in chemistry labs:

A small bar magnet sits inside the glass jar, while another bar magnet, attached to a motor is spun underneath the jar. This causes the first magnet to spin too, thus stirring the liquid.

But I'm sure it must be possible to do this without the motor underneath, simply using coils. Either a brushless motor or a stepper motor.

And now my question:

Is there a name for such a motor, where there are coils on one side of a sheet of glass (or similar), but the rotating / permanent magnet part is on the other side?


texts:
I was wondering if anyone could help me identify these thermistors. They were included in a grab bag I recently purchased and I haven't been able to find any information about them.

The numbers on the thermistors, from left to right are: 823, 821, 561, 103, 56, and then what appear to be 3 dots(?). Are these values in ohms, kilohms, megohms?


texts:
I am working on a schematic that requires the operational amplifier MC34072P but I couldn't find it here in local stores!
So, anyone would suggest any substitute to use? I'd be grateful.
And by the way, what are the basic things should I look at in specs to compare such ICs?
Thanks in advance!


texts:
In the following system,

I created the following equation in terms of what I assumed to be the force acting on the movable object with a mass M. The reluctance of the core is neglected, so the total reluctance of the system only consists of the air gaps:
\begin{align}
       \ddot{x}m + kx - \tau &= 0  \\\\
       \ddot{x}m + kx - \phi R(x) &= 0 \\\\
       \ddot{x}m + kx - \phi \frac{2x}{\mu_{o}A_{Gap}} &= 0
\end{align}
The solution however, has the following formula for the force applied on the movable part:
\begin{align}
       F_{Gap} &= \frac{\phi^2}2 \frac{dR(x)}{dx} \\\\
               &= \left(\frac{Ni\mu_{o}A_{Gap}}{2x} \right)^2
                  \frac{1}2\frac{2}{A_{Gap}\mu_o} \\\\
       F_{Gap} &= \frac{(Ni)^2\mu_{o}A_{Gap}}{4x^2}
\end{align}
Where was the solution's equation derived from, and why is the mmf not used instead?


texts: Pc lpt (parallel) port input pin, how much current does it draw

texts:
I need some help to understand what's going on with my project:
I am building an cnc machine and i use the parallel port to communicate with it...
I use the native port to drive the motors and emergency stop. ( i purchased st v2 5 axis board which works fine)
For the limit switches i use a second lpt port provided by a pci express card.
Here i face the problem, with this card...
My limit switches are sn04-p2 (10v to 30v pnp normal closed)
I've built a board using octocouplers (pc123)
Since i can't feed 10v or 12v or 30v dirrectly to the lpt port.
So what does this board do? Isolates the 12v (currently used by limit switches) from the 5 volts that is feed into the lpt port to keep the pin high...

The optocoupler works, but i can't provide sufficient current on the 5v side to pull up the input pin from the lpt adaptor card...

If i feed 5v directly on the input pin works without problem. (Jumper from usb for example)
So i got my multimeter and measured the current drawn by the input pin ... and is 99-100 mA... which in my opinion is HUGE ...

Anyone know why? Or is this normal?

I feel safe using this "pull up/high" state, because if anything goes wrong with the limit switch, or wires, then no 5v and machine is stopped...

Thanks!


texts: How does Ethernet to CAN conversion work?

texts:
I am wondering how an Ethernet-to-CAN converter works. CAN is a multi-master broadcasting network where messages are associated with IDs. Each message type has a unique ID. Devices listen to all messages on the bus and decide whether an ID is of interest. Ethernet, however, uses point-2-point addressing, meaning that sender and receiver are specified. These information cannot be mapped on CAN, because there is not sender or receiver field.

Let's say, device A sends message m to device B. Device B is connected via CAN to the converter. Device A communicates over Ethernet.

How does the CAN-to-Ethernet converter select the message ID when converting an Ethernet frame to a CAN fame? Are the same CAN IDs used for packets to the same recipient?
How does the CAN-to-Ethernet convert a CAN message to an Ethernet frame? A CAN message has no recipient, but an Ethernet frame knows the recipient address. How does the mapping work?


texts: How to connect muRata XRCGB_F_M Series (XRCGB27M120F3M00R0) to microprocessor oscillator

texts:
This device as described in the data sheet (Crystal Unit (Crystal Resonator)) shows four pad pins (labeled 1-4) in an arrangement similar to ceramic resonator units. However, as shown in the diagram from the data sheet, only pins 1 and 3 are I/O pins, with pin 2 left as "Float" and bridged to the pad for pin 4. The recommended footprint shows four symmetric pads. I assume this means No-Connection (n.c.) from pin 2, not even to GND.

So is this device actually a crystal, packaged in a resonator can, but without integrated capacitors? If so, is the pad pattern just an accommodation to pick and place and reflow (this is an extremely small part of only .9 x 1.3 mm).

If only pins 1 and 3 are to be connected, can I attach short air wires to these pins and then use it in a breadboard for bring-up of the digital circuit, by adding the required 6pf load capacitors externally? (I realize the 27.12Mhz frequency will make this a challenge from a noise perspective, but perhaps good enough to get the micro to vibrate during board bring up?) The required 6pf load is less than the leads on my DMM and scope. Not sure how I will even test this in-circuit.

My reason for asking is that I cannot find any standard through-hole crystal with the required frequency.

This is a confusing package and there is no description of the functionality of this device in the data sheet (other than standard specifications and tolerances).

I would be grateful for an explanation from someone familiar with this family of parts.


texts: Is this dimmer compatible a DC 12v power supply?

texts: This power supply is used for LED strip lights I recently purchased. I want to know if the dimmer below can be used with the power supply. The PS is AC 100-240v (IN) to DC 12v (OUT), while the dimmer is DC 12-24v (IN/OUT), based on my intuition, this should work.


texts: How do power grids keep AC frequency synchronised across long distances with multiple generators?

texts:
Let's consider a simplified electricity grid - say there are two power plants (A and B) 1000km apart. There's a town (L1) half way between them, and another town (L2) some distance downstream from B. The time taken for the electricity to travel from A to B is about 1/300th of a second, so that would put A's output 1/5th or 1/6 of wavelength out of phase with (itself?) the time it's got to plant B. Does plant B synchronise to the plant A's phase as it is at plant A, or plant A's phase as it is when it gets to plant B? If the former (presumably using a global time source as the basis), then the two would be in phase when they reach L1, but not when they reach L2. If the latter, then they'd be in phase reaching L2, but not reaching L1.

simulate this circuit – Schematic created using CircuitLab


texts:
I have been working on an MPPT algorithm and I simulated on MATLAB , now I wish to test it practically.Can anyone suggest hardware or programmable MPPT charge controllers to which I can apply my algorithm?
Thanks


texts: CRT Oscilloscope - part of the plot is missing

texts:
I picked up an old METRIX OX 720 oscilloscope. I replaced 2 capacitors that went up in smoke.

Once restarted, here is the signal I get.

The vertical part of the signal is missing. It is the same for both channels.

Do you have an idea of the origin of the problem?

Is the quality of the probe responsible for the poor quality of the display? Or is it the oscilloscope that has a display problem, in which case is it good for the case?

Probe model :

EDIT : ADDIONAL IMAGES

I have modified the sweep rate time and fully increase the brightness but nothing changed.


texts:
I got a used Metcal station from ebay for my home-lab and everything I read about soldering with it is right, it is a completely different feeling.

I understood that stuff about controling the temperature using the Curie-effect in the soldering tip.

But I do not understand why they use 13MHz HF power to heat the tip. Why not DC, switched DC or 50HZ or 60Hz AC?


texts: SPI between ATmega32 and ATmega328 is not working

texts:
I have been trying to accomplish connecting ATmega32 and ATmega328 using SPI

Hardware connections:

ATmega328     ATmega32
master        slave
------------------
 MISO    ->   MISO
 MOSI    ->   MOSI
  SCK    ->   SCK
   SS    ->   SS

I have added some code to blink LEDs after each step to recognize if a particular step is completed.

When connected, the LED connected to master blinks once while LED connected to the slave doesn't blink at all.

What have I done wrong?

Thanks for any advice.

Code for atmega328 master

#define F_CPU 16000000UL
#include <avr/io.h>
#include <util/delay.h>

//Initialize SPI Master Device
void spi_init_master (void)
{
    DDRB = (1<<PORTB5)|(1<<PORTB3)|(1<<PORTB2);   // Set MOSI, SCK , SS as Output
    SPCR = (1<<SPE)|(1<<MSTR);                    // Enable SPI, Set as Master
}

//Function to send and receive data
unsigned char spi_tranceiver (unsigned char data)
{
    PORTB &= ~(1<<PINB2); //sending low signal to activate slave
    SPDR = data;                         // Load data into the buffer

    while(!((SPSR)&(1<<SPIF)));          // wait till transmission complete

    PORTC |= (1<<PINC4);
    _delay_ms(1000);
    PORTC &= ~(1<<PINC4);
    _delay_ms(1000);

    return(SPDR);                        // Return received data
}

//Main
int main(void)
{
DDRC |= (1<<PINC4);
spi_init_master();
unsigned char t = spi_tranceiver(6);
for(unsigned char i=1;i<=t;i++){
    PORTC = (1<<PINC4);
    _delay_ms(500);
    PORTC &= ~(1<<PINC4);
    _delay_ms(500);
}
}

Code for ATmega32 slave

#define F_CPU 8000000UL
#include <avr/io.h>
#include <util/delay.h>

void spi_init_slave (void);
unsigned char spi_tranceiver (unsigned char data);

unsigned char lo;

int main(void)
{
    DDRD |= (1<<PD7);
    spi_init_slave();
    while (1)
    {
        lo = spi_tranceiver(3);
        for(unsigned char i=1;i<=lo;i++) {
            PORTD |= (1<<PD7);
            _delay_ms(100);
            PORTD &= ~(1<<PD7);
            _delay_ms(100);
       }
    }
}

// Initialize SPI Slave Device
void spi_init_slave (void)
{
    DDRB &= ~(1<<PINB5);   // Set MOSI as input
    DDRB |=  (1<<PINB6);   // Set MISO as output
    DDRB &= ~(1<<PINB4);   // SS as input
    SPCR  =  (1<<SPE);     // Enable SPI
}

unsigned char spi_tranceiver (unsigned char data)
{
// Load data into the buffer
SPDR = data;
//Wait until transmission complete
while(!(SPSR & (1<<SPIF) ));
PORTD |= (1<<PD7);
_delay_ms(100);
PORTD &= ~(1<<PD7);
_delay_ms(100);
// Return received data
return(SPDR);
}


texts: How do I slowly short pins 2 and 3 of a phantom powered mic signal?

texts: Shorting pins 2 and 3 of a microphone signal will mute it and is acceptable for when phantom power is present. I can do this with a regular switch, or a solid state relay. But is there a simple way to do this with something like a MOSFET that I can slowly turn on? The turn on signal would be +5V from a microcontroller. I am not sure how 5V at the gate of a MOSFET and 48V at the source/drain would work, or it there is a specific part that would work well for this?


texts: Can flux residue affect sensitive ADC circuitry?

texts:
I have designed a product that uses a T.I. ADS1230 20-bit Delta-Sigma ADC.

I've assembled 20 prototype boards. Two of those boards are having completely insane oscillations (+30/-30 raw values) with inputs connected to a stable VREF/2. I've changed all the analog components to make sure that none is faulty, but the problem remains. The other 18 boards works as expected.

I'm trying to find an explanation of the problem but so far I got nothing.
After reading some forums of T.I. one of the engineers commented that flux residue that has not been properly cleaned after PCB assembly can impact sensitive circuitry.

Does anyone can confirm that?

P.S.: I always wash all the PCBs after assembly using isopropyl alcohol and a ESD brush to remove all soldering/flux residue.


texts: Effects of connecting speakers in parallel vs series

texts:
I have two 6Ω speakers and an amp that's rated 4-6Ω. I've done some research but it's inconclusive as everyone seems to have their own way of connecting speakers.

Doing so in parallel leaves me with 3Ω so that may fry my amp, meaning I have to connect it in series. The question is does connecting speakers in series vs parallel have an impact on volume and or sound quality?


texts: PCB Design Considerations - Copper Pouring

texts:
So after a very long effort, I think I've finally come towards the end of my PCB board design. It's a two layer board with no ground or VCC plains (Re-routing is not an option) as I can't go though the grief process again.

My question is should I use a copper pour?
Currently I have three possibilities which I am contemplating.

Do not use a copper pour
Implement a copper pour connected to nothing (no signal)
Implement a copper pour connected to ground
A brief example is below.
Unpoured PCB

Poured PCB with cross pattern

What are your thoughts and why?


texts: TinkerCAD schematic to Eagle for PCB design

texts:
I am new to the world of PCB design but I am having a hard time trying to convert my .brd file from TinkerCAD to Eagle. I've been following this tutorial for my conversion needs but it's almost impossible with the error I have been getting Link to tutorial.
Here is a picture of the error. .
I tried expanding the board area but nothing seems to stick and I keep getting the warning message. I also try to stick to the positive XY coordinates but that has been useless as well. Any tips on getting this design to work? Here is a picture


texts: Is it necessary to use a pull down resistor with this BTS7960?

texts:
I have an Arduino Nano  controlling a BTS7960 that is 10 meters away.
I have one 24V power supply.
Both the Arduino and the BTS7960 get 5V through a an LM2596 step down converter.
The BTS7960 "Enable" pins are hooked up to 5V output of the step down converter.

My problem is that this setup burnt the BTS7960   Before replacing it, I want to identify what made it burn.
I suspecting that either the RPWM and LPWM became both HIGH (from parasites + long wire ) and burnt the driver so I should add pull down resistors,  or there is something wrong with this configuration and using buck converters with common GND is what caused problems.
When I turn on the power supply the motor rotates for few seconds even though the Arduino didn't give orders to turn the motor on yet.


texts: PSpice error: '*$' is not a model parameter name

texts:
I am using OrCAD PSpice Student Edition, version 9.0, fairly old version (1999) but its what we have access to.

I've had this problem almost every time I use custom parameters for any model, which is requested of me for every Lab simulation. The process I usually do is click the model I want to edit (usually a transistor or MOSFET), go into:

and then click on Edit Instance Model (Text):

This prompt then pops up where I paste the custom parameters, terminated by '$:

When I try to run any simulation after, I almost always get an error stating:

ERROR -- '*$' is not a model parameter name

Removing the *$ terminator gives me another error entirely, so it is supposed to be there, I just don't know where. Is this a problem with how I formatted the lines perhaps?

Thanks in advance!


texts: Is every in-field stimulus replay-able during simulation?

texts:
I always though that simulation of hardware architectures (FPGA/ASIC) cannot cover every possible stimulus and corner-case that can be encountered in real conditions, and that hardware-accelerated verification is needed to cover real use-cases.

However, a friend told me that this statement is wrong. Every transaction can be recorded and replayed during simulation. The only issue is that it would often take days or months to complete the simulation (like testing 10s of an H264 stream sent to a decoding IP).

This makes sense to me, but since we're both working in a lab research unit and not in an industry verification team, I wondered: is my friend right?

On a side note, it's quite unbelievable that this stackexchange site has no verification tag...


texts: Identifying which diodes are on in a full wave rectifier

texts:
For the circuit above, I am looking for which diodes are on during the positive and negative cycle. Is it safe to assume that I should just trace the path of the current based on where the diode is pointing?
For example, during the positive cycle, the current will enter node 1, then goes through D2 and D3. On the other hand, during the negative cycle, it will enter node 3, then D4 until it reaches D1. Is that correct?


texts: Is it safe to use replacement AC power adapter with a higher Input Amps rating?

texts:
I need to replace a damaged AC power adapter for a stair climber with an electronic display and controls.
The original AC adapter is labeled
Input:100-240VAC 50/60Hz 100VA
Output: 12VDC 5A, Positive Polarity.
A replacement I found is labeled
Input:100-240VAC 50/60Hz 1.5A
Output: 12VDC 5A, Positive Polarity.
The replacement seems to have about 1/2Amp higher input rating, could this pose a problem for the device or the replacement power adapter?  Or, since the output rating is the same, I shouldn't have any concerns with the slightly higher input Amp rating other than the draw on my electrical circuit breaker?
Is the following statement universally true if all other specs are equal?
"The input rating on a power supply is what it pulls when providing the maximum output rating. In the same way the maximum output of a power supply doesn't mean it must to supply that, the input rating doesn't mean it must to pull that."


texts: I created 2 simple blade configurations for a classroom wind turbine project. For our final evaluation of the project, we have to get our wind turbines to create the greatest voltage, at either high or low speed. Based on my own high-low speeds, I found that one, with only 2 thin blades, spun slower on the low speed and faster on the high speed. The other one, with 5 thin blades, spun pretty much exactly the same speed for high and low power (Faster than the low speed for the first blade, but slower than the high speed). Which one would produce the most voltage if they were wired the same? I heard that a faster spinning turbine might not generate as much voltage.


texts:
I'm currently working on a project where I have to take into account the resistance of the in series PTC fuse, however after reading the datasheet I found two specs for resistance Rmin and R1max. I did a little more research and I came across this application note which states the following:
"Figure 4 shows typical behavior for a PolySwitch device that is tripped and then allowed to cool. In this figure, we can clearly see that even after a number of hours the device resistance is still greater than the initial resistance. Over an extended period of time, the resistance will continue to fall and will eventually approach the initial resistance.However, since this time can be days, months, or years, it is not practical to expect that the device resistance will reach the original value for operational purposes"
So my question basically my question is the use of R1max as the resistance of the PTC fuse the general consensus for engineering desing involving PTC fuses?
Thanks


texts: Why does a battery starts working on rubbing?

texts:
Whenever my TV remote or wireless keyboard/mouse stops working,I take the batteries out and rub the two terminals with some rough cloth and it works fine.I've observed that this works a lot of times(not always).

What is the reason for this?

I'm guessing that some sort of thin oxide layer might have deposited on the battery terminals which I'm removing by rubbing it with rough cloth surface.Am I correct?

What might be other reasons for this phenomenon?


texts: PIC18, I2C Master Receive, Cant Read from SSPBUF to a Variable

texts:
I am using a Master PIC18F4620, Slave DS1307.
All I am doing is setting the seconds to (0) at the beginning of the program, then I read it.
I can't seem to read correctly, the value that is being returned from the SSPBUF register is the Slave+Writebit Address.
Everything is perfect on HW & Simulation, how is so?
I used an I2C Debugger on Proteus and it is all working fine, I am indeed writing and reading CORRECT values, I then checked using my PicKit3 Debugger HW, and I found out something very interesting.
The SSPBUF DOES transmit and receive, therefore its value changes, but the assignment statement from the SSPBUF to a variable FAILS.
#include "18F4620_Config.h"
#include "I2C.h"
#include "Generic_LCD.h"
#include "stdio.h"

#define _XTAL_FREQ 16e6
#define _RTC_WRITE 0xD0
#define _RTC_READ 0xD1
#define SEC_ADDRESS   0x00 // Address to access Ds1307 SEC register
#define CONTROL 0x07       // Address to access Ds1307 CONTROL register

unsigned char seconds;
char myString[6] = {0};

void main(void)
{
    LCD_Init();
    LCD_Clear();
    LCD_Print("Read:");

    I2C_Master_Init();

    DS1307_Set_Seconds(35);
    while (1)
    {

        seconds = DS1307_Read_Seconds();

        LCD_Goto(6, 1);
        sprintf(myString,"%x ",seconds);
        LCD_Print(myString);

        __delay_ms(1000);
    }
}

As for the two used functions.
void DS1307_Set_Seconds(unsigned char secs)
{
    if (secs <= 60)
    {
        unsigned char higher = (secs / 10) << 4;
        unsigned char lower = (secs % 10);
        unsigned data = higher | lower;
        I2C_Start();
        I2C_Write(_RTC_WRITE);
        I2C_Write(0x00);
        I2C_Write(data);
        I2C_Stop();
    }
}

unsigned char DS1307_Read_Seconds(void)
{
    unsigned char sec;
    I2C_Start();
    I2C_Write(_RTC_WRITE);
    I2C_Write(SEC_ADDRESS);
    I2C_Restart();
    I2C_Write(_RTC_READ);
    sec = I2C_Read_Byte();
    I2C_NACK();
    I2C_Stop();
    return (sec);
}

The only thing that is being printed right now is (D1) on the LCD.
I noticed another strange behavior, if instead of assigning SSPBUF value to a variable, I pass the SSPBUF as a parameter to the sprintf function, IT WORKS!.
Like this
while (1)
        {

            seconds = DS1307_Read_Seconds();

            LCD_Goto(6, 1);
            sprintf(myString,"%x ",SSPBUF);
            LCD_Print(myString);

            __delay_ms(1000);
        }

Edit 1: Solution
As mentioned in the comments, the solution is to read from the SSPBUF AFTER the I2C Communication has stopped entirely.
Therefore these are the code changes
void I2C_Read_Byte(void)
{
    //---[ Receive & Return A Byte ]---
    RCEN = 1; // Enable & Start Reception
    while (!SSPIF); // Wait Until Completion
    SSPIF = 0; // Clear The Interrupt Flag Bit
}

unsigned char DS1307_Read_Seconds(void)
{
    I2C_Start();
    I2C_Write(_RTC_WRITE);
    I2C_Write(SEC_ADDRESS);
    I2C_Restart();
    I2C_Write(_RTC_READ);
    I2C_Read_Byte();
    I2C_NACK();
    I2C_Stop();
    return (SSPBUF);
}

while (1)
    {

        seconds = DS1307_Read_Seconds();

        LCD_Goto(6, 1);
        sprintf(myString, "%x ", seconds);
        LCD_Print(myString);

        __delay_ms(1000);
    }


texts:
I want to do some prototyping with a microcontroller on a breadboard.

The microcontroller won't fit in the breadboard holes because it is square and small, and has many pins I won't be using.

I would like to connect the pins of the microcontroller to the breadboard via the standard jumper cables (22 AWG) to a female socket. I've tried to find them, with no luck.

Perhaps someone here could point me in the right direction?

Thanks


texts: Calculating Max distance from TX to RX that satifies SNR

texts:
I have two question, but they are both alike.

1) I am given a problem, with the following parameter:
B=20MHz, fc=2.4GHz, Ptx=26dbm,Gtx=15dBi, Grx=6dbi, receiver noise figure 5db.
and asked to find max distance bw tx and rx that satisfies SNR at receiver to equal or exceed 15dB. Assume free space propagation

I know If I am able to find the power at the receiver than I can find d

Prx= Ptx*Gtx *Grx (λ /4πd)^2

The only problem is I have not been able to find one single example that illustrates about how to find Prx with my given parameters. I know I am given enough info to calculate N= kTB.

2) I am given roughly the same parameters only this time I know d. Is there any equations one can use to find the min transmitted power?


texts: Understanding high-speed Improvements to discrete BJT multivibrator

texts:
What exactly are the Zeners doing in this circuit?
I've been trying to improve my understanding of BJT's, by trying to 'improve' the classic astable multivibrator. In an effort to 'sharpen' the transistions, I included a Zener diode between the capacitor and the base of the transistor. My thinking was to 'protect' the base from the capacitor charge curve until it was well past the ~0.7V threshold. What ended up happening instead was an increase in oscillation frequency, and an increase in oscillation stability with very small capacitance values.
With the 'classic' multivibrator circuit, I can only get to about ~100kHz. With the Zeners  (as well as R7,R8 and R9), I see stable oscillations well into the low MHz range.
Can someone help me understand how to analyze how the Zeners are working?
[The breadboard circuit performs very similarly to the simulation in LTSPice, in this case, about 3MHz with rise/fall times <10ns]


texts:
I am trying to embed code in my Attiny4 project that will set fuses and lock bits(In AtmelStudio 7).
I copy/pasted the code that Atmel suggests here:

#include <avr/io.h>

typedef struct _tagConfig
{
    unsigned char f1;
} Config;

typedef struct _tagLock
{
    unsigned char f1;
} Lock;

typedef struct _tagSig
{
    unsigned char f1;
    unsigned char f2;
    unsigned char f3;
} Signature;

Config __config __attribute__((section(".config"))) =
{
    f1 : 0xfb, // Set CKOUT
};

Lock __lock __attribute__((section(".lock"))) =
{
    f1 : 0xfc, // Further programming and verification disabled
};

Signature __sig __attribute__((section(".signature"))) =
{
    f1 : 0x03,
    f2 : 0x90,
    f3 : 0x1e,
};

Then i try to compile and it directly fails with the following errors:

attiny4-fan.elf section `.config' will not fit in region `config'
region `config' overflowed by 1 bytes
ld returned 1 exit status
recipe for target 'attiny4-fan.elf' failed

I can't seem to find any other information on how to do this for an ATTiny4/5/9/10. The Datasheet seems to mention something about the locations but since i have never done this before, especially not for the Attiny4 i'm playing with here, i have no idea on how to proceed.

This is the output of

avr-objdump --section-headers

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         000000c8  00000000  00000000  00000074  2**1
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  1 .data         00000000  00800040  00800040  0000013c  2**0
                  CONTENTS, ALLOC, LOAD, DATA
  2 .bss          00000003  00800040  00800040  0000013c  2**0
                  ALLOC
  3 .comment      00000030  00000000  00000000  0000013c  2**0
                  CONTENTS, READONLY
  4 .note.gnu.avr.deviceinfo 0000003c  00000000  00000000  0000016c  2**2
                  CONTENTS, READONLY
  5 .debug_info   000002ab  00000000  00000000  000001a8  2**0
                  CONTENTS, READONLY, DEBUGGING
  6 .debug_abbrev 00000284  00000000  00000000  00000453  2**0
                  CONTENTS, READONLY, DEBUGGING
  7 .debug_line   000000d3  00000000  00000000  000006d7  2**0
                  CONTENTS, READONLY, DEBUGGING
  8 .debug_str    000000f6  00000000  00000000  000007aa  2**0
                  CONTENTS, READONLY, DEBUGGING

In the mean time, i also found out that in the ATtiny DFP header file for the Attiny4/5/9/10, the following macros are defined(ATtiny9 as example):

/* Fuses */
#define FUSE_MEMORY_SIZE 0
/* Lock Bits */
#define __LOCK_BITS_EXIST
/* Signature */
#define SIGNATURE_0 0x1E
#define SIGNATURE_1 0x90
#define SIGNATURE_2 0x08

Why would FUSE_MEMORY_SIZE be defined as 0?

Can anybody help me to get my ELF to contain fuses and lock bits?


texts: Microcontroller programming using universal programmer tool

texts:
I am using NXP P89LPC954 microcontroller. I am having problem with In System programming(ISP). When i solder it on my board for the first time and try to burn hex file into it using phython chip prog, all the process i.e burning the hex file and verifying after burning, everything goes fine in the chip prog software. But the microcontroller does not behave as per the code.

When I burn the same hex file using "universal programmer"(De-soldered microcontroller inserted in the Device pins ) having parallel port, it works fine. Once the code is burnt using parallel port device, from next time onwards i'm able do the isp programming.

Actually i was told that we must dump any microcontroller for the first time using universal programmer only to make it compatible for isp. But what i feel is if that is the case then why not the manufacturer does that by default(As it is not user program dependent)

Is it required to program all microcontrollers for the first time using parallel port universal programmer only,to make it compatible for isp??


texts: STM32F411VE Custom bootloader USB de-Init issue causing Jump to app fail

texts:
I'm developing a custom a bootloader on STM32F411VE MCU which must download a .bin file from USB key and flash it into the application sectors of flash memory.
Following the examples provided with cube libraries i managed to open correctly the file with the FAT FS system, but I'm having hard times understanding how to exit from the bootloader and jump to my app.

These are the scenarios:
1) Power on the board with no USB Key inserted; the code has no usb stop/deinit/disconnect call -->boot ends its function and jumps correctly to the application. If I plug the USB key during application-life the system reboots. Note that in my application I have no USB driver running
2) Power on with USB key inserted; the code has no usb stop/deinit/disconnect call --> boot fails when setting the MSP of the application:

__set_MSP((uint32_t)*APPLICATION_START_ADDRESS);

3) Power on with no USB Key inserted and USBH_Stop call before jumping to app --> boot fails when setting the MSP of the application

This is my Jump to app implementation. It worked optimally before inserting the USB Host driver

static void JumpToApplication(void)
{
 void (*pmain_app)(void);
 /* First, disable all IRQs */
 __disable_irq();

 SCB->VTOR = (uint32_t)APPLICATION_START_ADDRESS;
__set_MSP((uint32_t)*APPLICATION_START_ADDRESS);

pmain_app = (void (*)(void))*(APPLICATION_START_ADDRESS + 1);

pmain_app();
}

Thanks a lot for supporting me


texts: Please help me explain the overshoot and undershoot in CMOS inverter

texts:
Rabaey book says that:

  Notice especially the overshoots on the simulated output signals.
  These are caused by the gate-drain capacitances of the inverter
  transistors, which couple the steep voltage step at the input node
  directly to the output before the transistors can even start to react
  to the changes at the input.

But i am still not so clear about input output coupling effect. Please help me!
Thanks


texts:
I plan to use KC5032A40 as a clock source for CoolRunnerXPLA3 256. I power it with 3.3V and interface it as suggested:

I perform the measurement at the Test Point and do not add any CL capacitance, the probe is set to 10x. Instead of getting theoretical 0V and 3.3V swings, I see -1V to 4V swings:

Questions:

Is this a correct measurement? Will the oscillator provide proper voltage swings with some  load on the output?
Is this a reasonable choice for my application? Any suggestions for oscillator choice to drive CPLD?
Is it a proper practice to connect the oscillator to any IO pin, or it should be connected to the one of the special CLK0:4 pins (table 4 of the manual)? What's the purpose of such pin  as IN0/CLK0?
Could I also use such oscillator as an external clock for a microcontroller instead of XTAL oscillator?


texts:
I made a multistage transistor circuit to see, with such a high gain, what the output would be?

(Bottom Terminal to +5V, Top Right Terminal to Gnd)

I've seen circuits with three transistors in this fashion, being used to detect an AC source nearby. The base of the first transistor is connected to an antenna sort of structure and when bought near AC source, the LED turns ON. So I  thought to add more stages to see what else it can do?

I expected that it may detect the RF communication signals or it may detect any AC source from much larger distances(I guess I was expecting miracle out of a random built) . But it showed wierd behavior. When powered, it would turned the light ON and when any part of the circuit is touched with a finger the light turns off. And after releasing the finger, the light slowly-slowly rises to its maximum brightness again, until it is touched again.

When it does not behave like just described, it behaves like this:
When I move close to the circuit light intensity increases and when I move away it decreases.

I have vague idea that it may have something to do with the capacitance between me and the circuit, but I don't understand how exactly it work out for this circuit? Is this phenomenon well known and is this thing studied under any subject?


texts: Is the Holzer effect the same as the Hall effect? (looking for replacement sensor)

texts:
I was looking for a replacement component for what I thought would be a "Hall effect sensor" (used in an electric scooter throttle handlebar). I had bought a replacement throttle about a month ago, but now it's dead again so I dismantled one of them and figured I'd just replace the sensor this time.

Here's a scanned image of the sensor (the white is some glue they used to keep it in place):

A search on S49EH got me to the site of the Chinese manufacturer, who claim it is a "Holzer element". Wikipedia has no mention of "Holzer" on the Hall effect page, however another source seems to describe the same effect calling it the Holzer effect. Is it really the same or is there a slight difference I missed?

I'm still at a loss to find a correct replacement though. A search at my local electronics dealer on "nonlineair hall-effect sensor" gave zero results. they do have linear, digital, switching and others. After looking at a lineair version, it seems to be outputting 50% of the voltage when detecting no magnetic field, which is not desired. The output should be between the input (5VDC) and 0.

Doing some experimenting, it seems that using a potentiometer of 10K also has the desired effect (only mounting it on the throttle in a safe way would be quite a challenge).

Also (maybe this should be a separate question), what can I do to prevent the new sensor from breaking once again? According to the specs the old sensor should be able to handle 24Volts, while I'm only measuring 5 volts on my scooters throttle. Placing a serial resistor would decrease my maximum speed so that's not an option. Maybe putting a small capacitor between the input and GND would buffer some voltage peaks?


texts: How to approach digital electronics questions

texts:
I have an interview to a board design position, and I assume I'll be asked about digital electronics, so I'm reviewing some of the material by searching for questions online.

I'm seeing questions like:

Give a circuit to divide frequency of clock cycle by two.
Design a simple circuit based on combinational logic to double the
output frequency.
Implement D- latch using a multiplexer.

And so on.

While I have the knowledge, I'm still not sure how to approach these kind of questions where you have to design circuits. Is there some kind of method, technique to do so?

Forgive me if this is a broad/generic question.


texts: Building a cheap and stable microwave network analyser or oscillator (2-5GHz)

texts:
I am interested in measuring the changing dielectric constant of a liquid as it undergoes a process.  My background research of scientific articles shows that the 2-5GHz range provides the best contrast between the before and after dielectric constants of this liquid. In those papers they use a vector network analyser which is not suitable for me due to cost and the large size. Hence I want to develop a system to measure the dielectric constant at a fixed microwave frequency somewhere in the 2-5GHz range.

From what I understand I need a signal generator and a matched receiver. The output of the analyser will be connected to a coaxial cable with an open ended probe suspended in the liquid. What are recommended or suggested designs for such a device? It needs to be stable and reasonably cheap to make. Are there ICs designed for this? I note Analog Devices has a range of direct digital synthesis chips that look suitable but the prices become insane at the gigahertz range.

EDIT: Just to clarify, the design does not need to sweep. It can be a fixed frequency, it just has to be within 2-5GHz.


texts: Why do solar cells have very low efficiency?

texts:
Recently I came across a news posting about solar cells (the link is given below).

http://cleantechnica.com/2013/01/22/new-thin-film-solar-cell-efficiency-record-set-20-4/

It says that "A new conversion efficiency record of 20.4% has been set for thin-film solar cells by researchers at Empa and the Swiss Federal Laboratories for Materials Science and Technology."

I would like to know why the attainable efficiency of solar cells is such a low value.


texts:
In the fig below is the path from CLK of 1st FF to Output(DataOut1) a valid data path. If so why is it not shown? Is it because its just the combination of PATH2 and PATH3?

Thanks.


texts:
i'm using this serial topology to connect my STM32F1 slaves together to a master ESP32.

They are in total 10 STM32F1 slaves and one master:

With this type of wiring i'm sure that only one slave per time will talk back to master (when requested), now here comes the problem, basically i need dynamic addressing of slaves: they can be many (up to 30) and i need to access in order the slave devices.

In order to solve the "dynamic addressing" problem i'm thinking about that:

The first slaves will be plugged in and will send to the master his default address (i.e.: 0xFF)
The master will check if the address is used and then reply back to the device with the first available address (i.e.: 0x01)
The slave will get back the response from the master and set an internal variable with the new address (maybe it's a good idea to store the variable in a EEPROM like M24C02: enter link description here)

Starting from the next cpu cycle, the master will ask sequentially to all enumerated slaves to (for example) do an analog read using this workflow:

The master will send a message to the serial bus with address 0x01 asking to do an analog read
The respective slave will handle the request, read the analog input and then reply back to the master

I think that this can work, but i've not found any kind of this implementation...maybe i'm totally out of mind?

New idea and concept

Guys, what do you think about sequentially power up the circuits and using the same mechanism to assign dynamically the address?

This assumption will avoid me to save the assigned id to the eeprom and some other id software function defined functionalities like address reset, etc...

It can be a good (and dynamic) method to solve the problem, about that, how I can implement this sequential power up?


texts: In most text books and other electronics material it's said current is flowing through the circuit. Isn't this wrong? As current is flow of charge. Is there anything such as flow of flow of charge?


texts: Can you use less then the rated current on a High Side Smart Switch such as BTS555

texts:
I often see Minimum Current listed on the data sheets of some Smart Switches, Power distribution Switches etc.

For example in the data sheet of BTS555 it states that the minimum current is 128A so does that mean my load should be at least this value? Could I not use it to switch a load of 10A or evan 1A?


texts: How would I finish out this mini project (emitting 1 whenever 101 is read)?

texts:
Design a Moore finite state machine that detects 1 0 1 in consecutive
  digits in the input stream of 0's and 1's received every clock cycle.

  The circuit should output a 1 when it detects 1 0 1 as consecutive
  digits. Implement the FSM using a combination of sequential and
  combinatorial logic. Draw the truth table for inputs, outputs, and
  states. Draw the K-map for everything. Indicate how many flip-flops
  you are going to use. Draw the final circuit with the flip-flops.

Example:
INPUT:  0 1 0 1 0 1 1 0 1 0 0...
OUTPUT: 0 0 0 1 0 1 0 0 1 0 0...

This is my work so far, describing the state machine:

S_i   inp  S_{i+1}
000 -> 0 -> 000
000 -> 1 -> 001
001 -> 0 -> 010
001 -> 1 -> 001
010 -> 0 -> 000
010 -> 1 -> 101
101 -> 0 -> 010
101 -> 1 -> 001

Since there are only 4 states involved ("000", "001", "010", and "101"), I represent them with bits A and B:

     A | B
    -------
s_0  0 | 0    to represent state "000"
s_1  0 | 1    to represent state "001"
s_2  1 | 0    to represent state "010"
s_3  1 | 1    to represent state "101"

I combined this with the previous table to represent the initial states I_A, I_B, with some new input X, and then the destination states D_A and D_B:

I_A  I_B | X | D_A  D_B
________________________
 0    0  | 0 |  0    0
 0    0  | 1 |  0    1
 0    1  | 0 |  1    0
 0    1  | 1 |  0    1
 1    0  | 0 |  0    0
 1    0  | 1 |  1    1
 1    1  | 0 |  1    0
 1    1  | 1 |  0    1

I wrote out the K-maps for (I_A, I_B) vs. X for output D_A, as well as (I_A, I_B) vs. X for output D_B, and got this simplification:

D_A = ¬X * I_B  +  X * I_A * ¬I_B
D_B = X

I'm reasonably sure this is all right so far.

However I am unclear where to go from here. I don't really understand how to model this as an actual circuit using flip-flops. I don't know how to transition the initial states of A and B to their corresponding final states. I don't know how I am supposed to emit a 1 in the event that I end up in the "101" state s_3.

D_A = ¬X * I_B  +  X * I_A * ¬I_B
D_B = X

I don't really know if this is correct but this is how I tried to model the circuit:

I_B ------o-------------------------o
          |                         |
          |                         v
          |                         AND----->OR--------> D_A
          |                         ^        ^
          o---NOT---->A             |        |
                      N---->AND-----|--------o
I_A ----------------->D      ^      |
                             |      |
X --------o---NOT-------------------o
          |                  |
          |                  |
          o------------------o-------------------------> D_B

Where do I go from here?


texts:
What is the algorithm for the first pass and the second pass of an assembler?

I have been looking for a description or tutorial but haven't found one. If there are tutorials that explain these algorithms, please link them in the answers!


texts:
I have two 18V 1.5Ah batteries for power tool, which consists of five 18650 elements in serial (5s1p configuration). 18650 elements are of the same model, age and condition.
I want to make one battery from these two (so it become 5s2p), but my concerns are about charging the new battery. Can I use the same charging controller? Or I need to buy a new one? I want to use the same charger for the battery.


texts: What kind of sensor could detect the valve of a rotating soccer/rugby ball?

texts:
I am trying to design a device that will detect the air pump valve of a ball and then rotate it to a home position. It will most likely be controlled by an Arduino.

I am a mechanical engineer and have no idea about sensors. This is for a college project so I am looking for a reasonably inexpensive solution.

Thanks in advance.


texts: LM5134 mosfet driver Spice model not working in LTSpice

texts:
I downloaded the Spice model of the LM5134 MOSFET driver from the download page (*), created a symbol and created a schematic to test the model. You can download the zip archive containing the schematic, model and symbol here.

In the following I attached a screenshot from the schematic and a graph, which shows the voltage over time of the LM5134 pin OUT.
In my opinion, the graph should show an output of 12 volts and not ~0V. Since I'm new to LTSpice I'm not sure that I implemented the model correctly. Could somebody please review my model?

(*) Since I don't have 10 reputation I can't post a third link: ti.com/product/LM5134/toolssoftware


texts: Why gate - source and not gate - body voltage?

texts:
Considering an NMOS transistor with separate body and source terminals, with the following voltages: Vd - 10V; Vg = Vs = 5V and Vb = 0V, why wouldn't it conduct?

Isn't the channel of electrons formed mainly because of the potential difference between the gate and the body?

Is the source voltage disturbing the channel?