texts: How to stabilize the output square wave of a TL074CN (Comparator)

texts:
Figure 1

simulate this circuit – Schematic created using CircuitLab

I am using a TL074CN comparator to compare a fullwave rectified input voltage with a DC voltage of 1.4 V as shown in the above figure. At the output of the comparator, I am receiving a square wave which goes from +12V to -12V.

Figure 2

The figure 2 above shows the square wave generated in microsecond level. As you can see the waveform is very unstable at the moment. So far what I tried was

1) I also added a 100u capacitor at the output of the opmamp but it doesn't stabilize the waveform , it instead curves the waveform at the edges

2) I added a 10K resistor at the output but it doesn't help either.

3) I switched the TL074CN with an LM324N and still did not stabilize the waveform

Is there anything which I can do to make this square wave stable?


texts: AC circuit analysis with a transmission line involved

texts:
I'm trying to perform an AC analysis of a circuit that contains a piece of coax cable. The input voltage 'Vs' is a swept frequency (1MHz-150MHz) voltage source with constant amplitude. What I'm looking for is a method of calculating 'Vo' as a function of frequency.

I know all of the impedances, the segment of coax, and Vs.
Normally, with no t-line segment involved, I would do a mesh analysis, solve for the mesh currents, and then solve for 'Vo' as i3*ZL.

What methods can be used when performing an ac analysis of a circuit with a segment of transmission line involved?

A bit more about the coax:
VF=0.77,
er=1.69,
Vp=2.31E8 m/s

Thanks in advance.

AC circuit with T-Line segment


texts: Copy sub-room placement across channels in Altium

texts:
Consider an Altium project in which I have a channelized block.
Suppose also within that block, I use a sheet symbol to instance another sheet.
An example is shown in Figure 1.

The enclosing room U_mixer_stage, (which takes up the whole image) is channelized four times.
Inside that room are two rooms U_RF_amplifier and U_LO_amplifier coming from sheet symbols that are used in U_mixer_stage's schematic.

I know how to copy the layout of one room to another.
However, how do we also copy the placement of the sub-rooms within the enclosing room, and all of the associated routing?

I have also asked this on Altium Live.


texts:
I'm using this 1.2 V voltage regulator and having some serious problems.

Currently have +5 V going to EN and IN pins and GND is connected to GND, seeing ~1.6 V on OUT pin when connecting it to GND through 8k resistor.

I have been trying to figure out why the regulator is not outputting 1.2 V for days now and I am completely stumped.

Any ideas?


texts:
I have a challenge to push 500 Watts (15V) at 100 meters of telco telephone cable (0.088mm2, 28 AWG, 200Ohm/km, 500MOhm insulation).

The only way to achieve this is by boosting the voltage up to nearly 1kV and then - back to 15V.

The problem is that on the sinking side I have a very limited space (flat-hand barely fits), so cannot use any transformers.

Several sources on SMPS design seem to propose isolated topologies (is this for safety reasons?).

SMPS topology can be chosen from any type (yet, I'd prefer simplicity):

Boost or Buck
DCM Flyback
Forward Push-Pull
Half-Bridge
Resonant LLC

looking to this source, however, 1-3 is recommend for sub 150 Watt range. The rest are ok for 500 Watts, but all contain transformers which I cannot fit into the BUCK (not sure it that is a correct term to identify voltage down-conversion).

Ripple or EMI specs are of least importance (brushless motor will be powered).
Conversion efficiency, however, does matter.

I'd feed a rectified and smoothed AC input into the boost converter. I'd replace diodes with kV MOSFETS and would likely introduce synchronous functionality.
Inductor would probably require a careful winding to consider spark gap for the given voltages.

Could you please comment if this is a very bad choice?

By considering the constraints, what alternatives do I have on the BUCK-side then?

And I'd simply convert it down, most likely in synchronized fashion too.


texts:
Is there a common symbol for PLLs, either for schematics or functional diagrams?

I need a symbol which would be easily recognized as a PLL, without having to draw the phase comparator, loop filter, and VCO separately.

Otherwise, I'll resort to just drawing a square and writing "PLL" inside.


texts: Should I double data or power lines for UART device

texts:
I just have a quick question.
I'm connecting PN532 NFC reader with RPi, for this I am using around 30m of UTP cable from my front door to rack with RPi, preliminary test showed the device is able to communicate over 30m of cable in UART mode - with data and power each via single pair.
Now I have one pair in UTP cable free, should I use it to double-up the power (3.3V, GND) lines or data (TX,RX) lines which use 3.3V signal? This will drop that pair's effective resistance and increase their current capability. What makes more sense to make it more reliable? Max current is around 100mA for the NFC reader. I measured the voltage at the end while max power consumption at 3.1V (datasheet specifies 2.7V minimum for the PN532 chip)
I don't mean to double the lines for redundancy in case of one pair failing, but to minimize the voltage drop over the long distance of the cable, I am just not sure if giving it the double of the wire gauge is better for data or power (either using one whole pair for GND, second for 3.3V power, or one wire of each pair for RX and one of each pair for TX for data - to keep the benefits of twisted pair).
Thank you


texts:
I am trying to make a very simple module in System Verilog that receives a short pulse as an input, and returns as an output a pulse which is twice wider. For example, if the input is a 1ns pulse, then I want the output to be 2ns pulse. A delayed output would be even better.

I thought of making a frequency divider, but that won't help here, since frequency divider works with clocks, which rise and fall all the time, in contrast to a pulse, which will rise only once.

Thank you!


texts:
I'm trying to build a receiver signal circuit that will operate at 125khz. I'm using this receiver chip and this 125khz antenna. I tried breadboarding:
After connecting AS3933's VCC, GND, CS, SCL, SDI, SDIO pins appropriately to the Arduino, I connected one end of my square antenna to the AS3933's LF1P pin and the other end to Arduino's GND pin.
I then ran this code to check my AS3933's functionality. This is the message that I've got in my Serial Monitor :
test1: Checking AS3933 functionality

Tuning antenna LF1
Testing bit 4:
Frequency: 50

Testing bit 3:
Frequency: 50

Testing bit 2:
Frequency: 50

Testing bit 1:
Frequency: 50

Calibration for antenna 1 fails

Now from my understanding my AS3933 is functioning properly, but my antenna is at 50khz frequency for some reason. In the description it says that it is in fact 125KHZ antenna. Is the antenna that I've received faulty?


texts:
I have a 1000 times gain circuit using an INA826:

Up to 2mV input 2V out, it works fine, after that point in only gets up to 2.7V.

R? is a 6.2kΩ, that brings the 49.9 r to 49.5.


texts: I've created a project in CubeMX for my F7 Discovery. I followed instructions form here. However, in my Device Manager on Windows nothing appears. When I used precompiled code from link I was assured drivers installed on Windows works properly. MCU after checking this: if( hUsbDevice_0 ==NULL) returns from the function. What's wrong? Maybe I should use another function to enable something in USB module on MCU?


texts:
I am writing a code that when the key(0) is pressed, the letter shown on the 7-segment display changes from the one to the next, like a to b, b to c. It starts from A.
When the letter reaches H, it goes back to A. However, when I press the key, the letter changes,but it goes back to H when it is not pressed.I don't understand what the problem is.Here's the code:

    KEY : in std_logic_vector(1 downto 0);
    HEX : out std_logic_vector(6 downto 0)

    architecture behavioural of display is
    signal counter : std_logic_vector(2 downto 0):= "000";
    begin
    process (KEY)
    begin
    if (KEY(0)= '1') then
    counter <= counter + '1';
    end if;
    end process;

    process(counter)
    begin
    case counter is
        when "000" => HEX <= "0001000";
        when "001" => HEX <= "0000011";
        when "010" => HEX <= "1000110";
        when "011" => HEX <= "0100001";
        when "100" => HEX <= "0000110";
        when "101" => HEX <= "0001110";
        when "110" => HEX <= "0010000";
        when "111" => HEX <= "0001001";
    end case;
    end process;
    end behavioural;


texts:
I was breadboarding a pedal for my guitar using LM386. I read that as long as the gain is too large, the output signal is clipped to produce a distortion effect.

So I simply tune up gain pot between pin 1 and 8. But the output is as dirty as a cheap amp with overamplification. What did I do wrong?


texts: PCM5102A in 1.8V mode. Separate 0.1 and 10uF caps for DVDD an LDOO?

texts:
I found in the datasheet (33 page, 11.5.1) that when using PCM5102A in 1.8V mode, DVDD and LDOO should be both connected to external 1.8V. What's not clear to me is if I still have to put separate 0.1 and 10uF caps for both DVDD and LDOO pins as shown in the schematic provided in their datasheet. Here's how it looks like in my schematic:

Is this correct? Thanks


texts: Transfer Function of a pressure sensor - what does it tell me?

texts:
so I'm trying to get a pressure sensor for a water pump and in the Datasheets they state different transfer functions within the series. I know that the transfer function describes the input and output of a system. But when the datasheet gives this:
What does that mean? What is it describing?
I'm sorry if this is a very simple question.


texts: Device Driver function behavior on interrupt

texts: Suppose an embedded system is running FreeRTOS and an application program makes calls to a device driver interface (let us assume I2C). What exactly happens when this is interrupted by an external interrupt? In addition, how much sense does it make to implement the driver functions as tasks?


texts:
Hey guys as described here I also want to make a chess board with some arduino support.
Here I want to ask some questions regarding the schematic and the pcb layout I am planing to do. @Dmitry Grigoryev describes a way to address the sensors by using a 1-8-demux. Due to the fact that my schematic skills are still not the best please bear with me. Anyway, I want to describe my idea briefly.

Schematic for field

For version 1 of our board we planing to integrate photo-resistor to determine whether a figure is on a field or not. For this I want to share a simple schematic:

This maybe looks stupid for some of you but these are my first tries.
My idea behind this is to use the photoresistor and the other resistor(where the resistance varies from field to field) as a voltage divider to determine which exact field is triggered by a figure.

Question 1: Is this feasible or does anybody has a better idea, then please share with me?

Communication with controller

We are aiming to use a Arduino Micro/Nano or Mega if more memory is needed.
For the communication we choosed the MCP23017 - I/O-Expander.
So every field is connected to one out of 4 controller(64 fields = 4 * 16bit I/O expander). I know its an analog signal but all I need is just a 'hey i got triggered' signal.

Question 2: Is this also feasible or does anybody of you has a better and more clean solution. More maintainable and more expandable for future versions.

PCB

I am planing to create a PCB out of all ideas that are expandable for other usecase(e.g. adding ADC etc. or something like this).

Same question as former ones also.

Puhh I hope I added everything and the question full-fills all stackexchange standards. If not, please provide feedback to enhance my question.


texts: How does a crystal radio headset act as a lowpass filter to remove the carrier wave.?

texts:
I saw a similar question " How can a diode act as a detector in a crystal receiver"  but one of the comments said "after the diode splits the wave form to the top half ...the carrier must still be removed from the signal". The implication was that the headset did this.

I though a kind person would take me through the steps again just beginning in front of the diode so I don't miss anything.  Thank you much


texts: Do all USB-C compatible devices have USB hubs inside of them?

texts: Since the signals on the USB-C connector are mirrored on each side with the CC pins indicating the plug orientation, does this mean that all USB-C devices have USB hubs so they can use the right D+/D- pair, or the right superspeed RX/TX pair?


texts: Solving Boolean Expression (A' B' C')+(A' B' C)+(A' B C')+(A' B C)+(A B' C')+(A B' C)+(A B C')

texts:
I have this boolean Expression. But I'm stuck in this last step (i.e --> A'+AB'+ABC').

I know, it has to be simplified further, but I have no idea to gor further. Below is the simplified boolean expression that I could do...

Boolean Expression:

Q = (A' B' C')+(A' B' C)+(A' B C')+(A' B C)+(A B' C')+(A B' C)+(A B C')

= A'B'(C+C')+A'B(C'+C)+AB'(C'+C)+ABC'

= A'B'(C+C')+A'B(C'+C)+AB'(C'+C)+ABC'

= A'B'+A'B+AB'+ABC'

= A'(B'+B)+A(B'+BC')

= A'+AB'+ABC'

= .....................

= .....................

= .....................

= .....................

From here I don't know how to simplify further... Can anyone please help me?


texts:
The following circuit is a non-inverting amplifier with a normal op-amp. I know how the "classic" one works: Vout/Vin = (R1+R2)/R2. However, there is a third resistor R3. As far as I know, it has something to do with an offset voltage. May someone explain what it exactly does and how to calculate it (+ the amplification here)? The resistor values I have chosen are random.

Additionally, I have a second question. I recently saw an capacitor within a feedback. It wasn't an op-amp but a differential transistor amplifier. Basically, there was the same feedback like on the circuit above with R1 and R2 + a capacitor between R2 and GND (in series). What's the purpose for that?


texts: chassis ground and its location wrt common mode currents

texts:
This is related to chassis ground.
The chassis ground is connected to the system ground at the entrance of the cable that brings in signals and not at the other extreme or opposite end of the PCB. This will thefore prevent the ground plane from sending out common mode current into the rest of the system via the cables.

Now, many sites say that this is should be done close to the cable area physically.
Now, does common mode currents affect only the gpio signals via this cable or does it affect the power lines as well ?


texts: Showing three functions with Decoder 3-8

texts:
I`m trying to show 3 function with 3-8 decoder with only OR gates.
The following functions are:

F1 = A'BC' + AB'C' + ABC
F2 = A'B'C' + A'BC
F3 = ABC + AB'C' + A'BC' + A'BC

so what I did is:

I need to know if I did it right or there is something wrong in my decoder.


texts:
What can be done to repair or restore an ageing/dead/failing Li-ion rechargeable battery?

As they get older; they typically, gradually lose their capacity to hold a charge. What physical and/or chemical differences are there between new and old?


texts:
First of all i hope you will all excuse my spelling as i am Dyslexic.

I have two computer cases one is fully outfitted and has a sas expander to run 16 hard drives in it with a breakout to a backplane which is the cabled to a breakout on the 2nd case which goes to a 2nd sas expander which is plugged into a powered pcie mining board connected to an atx power supply for power and connects another 12 sas hdd's. There is no computer in this 2nd case.
What i am wanting to do is when the power button is turned on, on the first computer have it turn on the power of the power supply in the 2nd case and in the event that the computer is shutdown in the first case as soon as the power goes off have it shutdown the power supply in the other case. it would also be nice but not absolutely nessesary if this could also support sleep modes.

Can anybody point me in the right direction electronically as  to how to acheive this?

Cheers.


texts: Explanation needed on using 2 transistors as a switch

texts:
I'm suggested to use following design to drive a load with a micro-controller. I would like to know that why is it needed to use 2 transistors (n-ch and p-ch) to act as a switch and not only one?

I searched over Google and youtube, and most pages were using one transistor (mostly n-ch) to make a switch, like this page:

http://www.electronics-tutorials.ws/transistor/tran_7.html

Could you please explain me advantages or disadvantages of having such design (2 transistors) over one-transistor switches?

simulate this circuit – Schematic created using CircuitLab


texts: FT232R for RS-485 (DMX512) with Isolation - TX Optocoupler

texts:
I am trying to make a DMX controller board using the FTDI FT232R (FT232RL) chip for USB to UART and a MAX485 to output data over RS-485. I have a working prototype done, but for the finished product I am designing a PCB and want to add in isolation between the UART side and the RS-485 side.

The design I've come up with for the isolation is to use a DC to DC converter to isolate the VCCs from each other and an optocoupler (6N137) to isolate the FT232R TX pin from the MAX485's driver input.

So now for the question: For driving the optocoupler, can I use the TX pin with a \$470\Omega\$ resistor to sink the optocoupler's input cathode?
What I calculated is I need a minimum of 5 mA to make sure I exceed the LED threshhold. In the case of the lowest voltage difference of \$2.6V\$ (\$(VCC\rightarrow5V) - (V_{F,max}\rightarrow1.8V) - (V_{ol}=0.6V)\$), \$520\Omega\$ (\$2.6V/5mA\$) is the maximum resistance. (Specs below)

I can provide a schematic if that would help makes sense of all that I've said

(Note: The RX pin is not connected at all as I am doing DMX only, not DMX+RDM, so I have the MAX485 constantly driving)

6N137 Optocoupler

FT232RL FTDI USB to Serial


texts:
Please bear with me. It's easier asking you guys opinion than to Google.

Especially choosing the right resistor when working with Arduino boards and transistors for relays.

Question in the title: How to choose the right transistor for a circuit and its associated resistor?


texts: Is it possible to read DHT22 through I2C ADC (i.e. PCF8591)?

texts:
In my application I'm required to read all sensors through I2C bus. No sensors should be connected to MCU directly.

At this moment I need to read temperature and humidity (DHT22 sensor).
In order to read data from DHT22 I need to switch data pin to output first and then after some high/low operations and delay I can switch it to input and read data from sensor.

As an ADC IC I have PCF8591. I don't quite understand how to achieve this with PCF8591. Is there a way to do so?
Maybe I should be using other ADC/I2C?


texts: How to store one bit without the use of an IC?

texts: I am trying to store a bit of data from a circuit, but I don't want to use an IC like an EEPROM chip. Is it possible to store one bit with a transistor or something else to that effect?


texts: Bipolar Transistor HBridge Motor Driver:

texts: What is the importance of using the diodes shown in this Bipolar Transistor H-Bridge Motor Driver?


texts: Controlling pull-up pins from external circuit

texts:
I have a circuit with an Arduino controlling a 2-channel, normal-off, opto-isolated relay board, 5V input signals, turning relay ON when the Arduino digital pin is set LOW. The relays are controlled independently by 2 digital output pins of the Arduino.

One relay controls a 12VDC magnetic lock, the other a 220VAC stroboscope.

Into this equation, I want to add an Adafruit Audio FX Sound Board (Headphone Out jack version). Each of the 2 Arduino pins should trigger playing a sound on the FX board in addition to activating the relays. The FX board works like this: connect one of the 11 output pins to GND (I will be using only 2 of them) to trigger the sound associated with that pin. So the board is supposed to be used by attaching momentary push-buttons to those output pins. Adafruit says this:

  When the # pin is connected to GND for more than about 50 milliseconds
  it will trigger! There is a 100K pull up resistor on each one, so you
  do not need any extra resistors or pullups.

Ok, so they have 100K pull-ups. I don't see them in the schematics or the fab print of the FX board, so they must be using the internal pull-ups of the microcontroller.

This is a basic schematic of how I assume one of those pullups look like:

simulate this circuit – Schematic created using CircuitLab

I suppose I could use another 2-channel relay board, but that would be too much for this purpose.

I suspect the more elegant solution would be to use a NPN transistor, as seen here. Is this the best option? Should the GND of the Arduino share the GND of the FX board? Could 5V on the base control 5V at the collector? What values shoud the 2 resistors for the NPN be?


texts:
I have a device that runs on 2.5Vcmos logic levels, there are about a half dozen ic's with a mixture of parallel and serial (TWI and I2C) signal lines. Rather than placing my own uC on the board I'd rather have a arduino compatible header so I can use the new 32 bit arm arduino, but will also give me flexibility in using a R-pi or anything else in the future (just a custom header).

As such I need to translate about a 18 logic lines to my 2.5V cmos level but leave the other end open to whatever the UC is used to control it in the future.

I've been looking at two series of chips the Max3378 for SPI/TWI/I2C lines (one per device) and the Max3000 for the parallel lines. From the datasheet it seems they are perfect, biderectional with no external direction control lines, switching voltages with any user supplied Vcc (allowing me to just use the micro Vcc line without needing a seperate regulator on my board) and large bus widths minimizing chip count.

My question is, can I consider these chips "black boxes" that will work out of the box? are there any hidden caveats in their implementation? Are there special considerations I need to make to avoid noise getting in from the controller side (this is a mixed signal device with a DAC on board)

Additionally, there are several part numbers with the same overall design but with one-directional translation on some or all of the bits. Is there any benefit in using the one-directional version where bidirectional logic translation is not really needed (but may be in the future)? Using only bidirectional part numbers will simplify assembly and make it easier to meet minimum orders for quantity pricing.


texts: mini vacuum for PCB production? what's it called?

texts:
I made another attempt at doing a PCB with the UV exposure method except this time, I added two transparency sheets on top of the artwork and the lazer printer toner of the artwork touching the presensitized PCB board. The good part is the entire design appeared this time, but as I was assembling components, I had to drill larger holes just to get most of the components to fit, yet I was using standard eagle libraries to insert the components onto my circuit before printout, and I also printed at normal 1:1 scale.

I came across one website mentioning about using a vacuum to suck the air out between the PCB and the circuit board for better contact.

At first I was thinking placing the entire PCB in a clear plastic sandwich bag and tape it up to a household vacuum and leave the vacuum running for the entire exposure time, but that would give my family grief as well as raise electricity costs.

Does a tiny vacuum (and/or relevant parts) strictly for the purpose I mention exist for the general public to use? If so, what's the technical name for it?

I'm just sick of my PCB production going wrong all the time and I feel if I can get the artwork to go 100% flat to the PCB with zero light shining in the wrong places then I'll buy the necessary equipment.

update

Would heat shrink wrap bags work?

I remember heat-shrinking the shrink wrap on my windows in my house back in the day to keep the cold air out and I ran over the wrap with a hair blow-dryer for a good 20 minutes and the wrap produced a really tight seal on the windows. I see that ebay sells heat shrink-wrap bags in small sizes that can fit my circuit board as well as my multi-function printer transparency (bought from Staples office store). The question is, would this approach work? or would the blow-dryer melt the transparency and/or screw up any part of the circuit board (especially the photo-resist layer)?


texts:
I am designing a measurement system based on a single pin.  When the pin is connected to GND, it means move right.  If the pin is not connected to anything, no action happens.

The system was contolled by button switch originally, but I want to control it with a mouse such that when the mouse moves right, the pin is connected to GND, and when the mouse don't move, the pin is connected to nowhere.

I have tried to connect the pin to an Arduino UNO's 3rd pin. Whenever mouse's rightward moving is detected, the 3rd pin should be connected to ground.  When the mouse's moving is something else than rightward, the Arduino UNO's 3rd pin should work as if it was not connected.

I think that making the 3rd pin act as GND can be done by analogWrite(3,0), but how can I simulate "connected nowhere"?


texts: Confused how to find the transfer function of a low-pass filter

texts:
I know that \$H(\omega) = \frac{V_o}{V_i}\$ but I don't quite understand why this equals \$\frac{R}{R+j\omega L}\$.

I understand that \$V_o = IR\$ but don't quite understand how \$V_i = I(R+j\omega L)\$.


texts: Reduce idle current consumption of 28byj-48 stepper motor

texts: I have a question to ask. I'm using this stepper motor and found out that even the motor stop to the desired position, it still feeling hot and I guess it still consuming the same current as it move. But is that a way to reduce it? Don't tell me to choose pricey stepper motor because I want to use low cost to do this project. Thanks.


texts: Is there risks or limitations to install driver board under a pinball playfield?

texts:
I'm currently designing the electronic for a pinball. I would like to reduce the usual cable mess under the playfield. I'm thinking of creating small driver card that handle small amounts of switch, coils and lamps. Those card will be connected to a bus connected to the mainboard. Several driver cards would be placed under the playfield closer to the action.

Is there any risks from vibrations, heat and magnetic flux? Could it influence reliability and aging of the system?


texts: Problem about Nyquest signalling theorem?

texts:
A sinusoidal signal with amplitude 20 V and bandwidth 35 kHz is sampled at 2.5 times its Nyquist rate and then quantized using a 128-level quantizer. Determine:

i) The resulting data bit rate?

The Bit rate= 2Wm=2(35K)(7)(2.5)=1.225M bit/s

ii) The Signal to Quantization Noise Ratio (SQNR) in dBs of the resulting sampled signal assuming the sinusoidal signal amplitude covers all levels of the quantizer?

I know the power of the signal , But how to get the noise power.?

iii) The minimum required baseband channel bandwidth needed for transmitting the digital bits assuming that Manchester line coding is used.

The required bandwidth is 2R= 2(1.225M)

Can someone help me solving this problem ?


texts:
I want to output signal in current form (4ma - 20mA) from arduino. I plan to use DAC to get high resolution analog signal 0-5V, but how to get convert if from Voltage form to Current form is not clear jet to me. Please suggest me how to achieve it. So some simple but still stable, good DIY circuits or some relativly cheap products (shields,...)

Thank you.

Damir


texts: Do all/most SOIC chips whitstand the 235 degrees C for reflow soldering?

texts:
I want to try reflow soldering for several projects (small scale).  For some of the components (e.g., resistors and ceramic capacitors), the datasheet does give specific information about maximum temperature, and some of them even have a (very detailed) drawing of the recommended reflow temperature profile!

However, not all of them.  For example, I have the AD8421 instrumentation amplifier which does not say anything;  the Absolute Maximum Ratings section includes the Maximum junction temperature, reported at 150 °C.

I'm not sure what this "maximum junction temperature" means or represents; but it is more than 30 °C lower than the melting point of tin/lead solder, so hopefully it says nothing about the maximum soldering temperature.

As the subject says:  I'm just wondering whether I could blindly trust that all (or at least the vast majority of "normal" SOIC chips) will resist the few seconds at 235 °C.

Any comments / advice will be appreciated.


texts: What is the relevance of "typical values" in datasheets?

texts:
When working on a design I always work with minimum/maximum values from the datasheet (whichever is worst case), never typical values. I was reminded when in another discussion the leakage current for a BAS416 diode came up: 3pA typical, 5nA maximum. That's a factor 1000! In this case I surely would dismiss the 3pA.
What's the relevance of "typical values" in general? Do you use them in a design?


texts:
I was going through an app-note AN2606 where I came across this connection diagram:

As per my knowledge, UART is push-pull type and Tx provides the pull-up required and hence we don't need to use any external pull ups. Am I missing something here?


texts: Does PWM power supply divide the current drawn of a non-inductive Load along with the divided apply voltage?

texts:
Let say I have non-inductive Load and it is rated as follow:

0.2A @ 1V applied
2A @ 5V applied

Which is powered by a DC battery and is rated as follow:

5V output
1A max current supply

I am going to divide the supply voltage by switching it with PWM, say 20% duty cycle and as a result we can simulate a 1V voltage is applying onto the Load. In this case, may I know how much current will the Load draw? As it is a non-inductive Load, does it mean that it would (tend to) draw 2A current for every high state in PWM (because high state is 5V)? However, the battery can provide only 1A at maximum, so it may not work properly.

OR... Should I just treat it as 1V applied and so that the current drawn by the Load should be only 0.2A?


texts: What is optimal way to supply voltage for MOSFET gate driver circuit

texts:
Most FET Vgs are about 7 to 15V, if we use supply voltage in this range we can feed supply voltage to gate driver ICs or circuit.
But, what if our circuit work on higher supply voltage range,says 9 to 25V.
What is optimal way to regulate voltage for gate driver that work for whole supply voltage range?
As far as I known, for this application, I don’t need much current and don’t need precise voltage.

Linear regulator can work but may not work at low voltage supply due to drop out voltage
LDO Linear regulator is doing  better job at low voltage.
Buck converter seem to be overkill for such a low power and suffered from ripple and noise.
Zener diode + Resistor at gate. Seem not efficient at high supply voltage.
Zener diode + BJT as regulator, I found this method in Chinese tl494 boost converter. Seem to work with cost efficiency.


texts:
While I was studying the use of Transistor as an Oscillator from my Fundamentals Of Physics By Halliday, Resnick and Walker , I faced several confusions.
My book says that when the switch S1 is closed, the collector current starts flowing , its value slowly increases, as shown by the segment XY and thus emitter current is induced in the input circuit.

My question is why the collector current increases slowly and why Emitter current increases with increase in collector current? Also what is the significance of the cell between base and emitter when it is receiving voltage through mutual inductance? Please help me in the stand.


texts: Why is i4 (E4) equal to zero? How can I arrive at that conclusion?

texts:
I'm a newbie who just started studying EE and I'm presented with this problem as shown here.

I have to calculate all currents, meaning I1, I2, I3, I4, I5. I have the value of each resistor and the value of the current source I, which is 1A.

Now, for I1 I did the following: I added R2 and R3 (I think it's doable because there's an empty wire between them and R4...) and then I multiplied that value I got with R1 and divided it by the sum of those 2 components...

Basically it was 30 * 20 / 50 and I got 12 ohms.

Now I use the formula for calculating current. I1 = I * R4 / (12 + R4)
So now I1 is 0.6A. This value is correct.

To get I2 I can use Kirchoff's current law and I get that 1 = 0,6 + I2, from which I get that I2 = 0.4. So far so good.

Now, how do I go about calculating the rest?

Since I5 is an empty wire, can I just say that the current there is the same as I2?

According to the solutions presented I5 is 0,4 too, I3 is -0,4 and I4 is 0. Now I know that I = I1 + I2 + ... + In... so the sum of all these Is must be 1. But why isn't I4 0.4 and I5 0?

What's the thinking behind it? I'm just not very clear as to how this works.

Thanks


texts: Why does peak torque increase on increasing air gap in induction motor?

texts: I have been trying for a while to summarize the effects of increasing air gap in an induction motor with constant load. I understand that increasing air gap with constant supply voltage demands high magnetezing current for the same magnetic flux, and this also causes reduction in power factor. But I also found that maximum torque or breakdown torque also increases on increasing air gap. However, an increase in air gap should also cause increase in leakage reactance, to which the maximum torque is inversely proportional. Hence its value should decrease but the opposite happens. So, what is happening here?


texts: Determining motor speed and torque given a power and constant voltage

texts:
I'm trying to determine at what speed my brushed dc motor will run at, given a certain power dissipation. The background is I've built a lathe, using this motor, and for a given depth of cut and feed rate (which is dependent on motor speed and how fast I turn the z axis handle), there is a certain power requirement to remove that much material. Calculating the power is easy, if I make an assumption about the motor rpm, but if I'm running the motor at 12v, I don't have direct control over the speed, just the range of speeds, correct?

So, if I set the voltage, then attempt to stall the motor (huge depth of cut or very high feed rate), I will draw max current, and have zero speed, or I can take no cut, and have essentially the no load speed. For a given cut though, I can find the power, but there are two points along the torque speed curve (other than max power) that give that power, so how do I know which point I'm at? The high torque low speed point, or the high speed low torque point?

Thanks!


texts:
ST AN1946 p.10 says: "The zero-crossing detection can also be done when PWM is in an "ON" state if the compare value is set to the half value of the DC bus."
It makes complete sense, if we're assuming that the other two windings are just a voltage divider. But we're observing the phenomenon that the voltage value during PWM is not half DC but higher. Somehow it depends on the duty cycle and who knows what else.
I measured and plotted ADC values on a disconnected winding; the green line represents the Vdc/2. On the scale, you can see the actual zero-crossing time, and at that time the offset is far from Vdc/2. What is causing this phenomenon? How to find the zero-crossing value when PWM is on? Thanks.
Measured and plotted ADC values on a disconnected winding:


texts:
What's the name of this output connector of ac adaptor :

Thank you for your help


texts:
I'm trying to change the voltage regulation circuit in order to obtain a different range of voltage. My feeder uses a diode bridge and a transformer, that are not displayed in the scheme(it works).
My questions is: my new voltage regulator (with the pnp) is able to activate my npn (already present in my old feeder) in order to erogate at least 20A current? Thank you

EDIT: The voltage regulator that I use is LM317, R3 and R4 are trimmers, used to regulate the maximum and minimum output voltage, and R2 is a potentiometer used to regulate the voltage in the min/max range.
The pnp I think is used to polarize the npn(s), as reported in the lm317 datasheet:

EDIT 2: I have modified the circuit as follows:

These changes are sufficient? I can try to create the circuit? thanks
(The 0.6R resistor was a load trial)


texts: What influences capacitor maximum current handling?

texts:
In this answer it is said that the maximum capacitor current handling is "largely a mater of losses", what I can understand that is a factor for maximum dissipation.

So, what is the thermal impedances related to capacitors, in general electrolytic?

That is, does the case have a low thermal impedance to the inside, so a bigger capacitor
will generally refer to best current handling? Or is the terminals?
Taking the more available capacitors, some can say that being it or not, large current
capacitors have large terminals, but not so relative to the current itself, I think.
Does snap-in have more current handling capacity, or they price is higher just because
of the mount type?

Of course if you have the data-sheet of the component you can take the parameters, but is not so common to find capacitors with data-sheets, or from capacitors taken from damaged equipments.

Also, does good dissipation of the capacitors can help both in current handling and MTBF?


texts:
I'm not usually one to turn to these online forums, but I'm working on designing a circuit to meet the following requirements. My only problem is I'm unsure of how to begin it and have nobody to turn to for help. Any and all help is greatly appreciated.

So far I've thought that maybe a method of using switches to separate the original voltage into lines with varying resistors might work. I also believe I'd need my meter to go at the end of whatever circuit I end up designing.
To summarize I'm thinking 1 voltage source (DC); switches to separate it to reduce the voltage and some method to get a single output to match the criteria? Is this something that's possible or should I keep brainstorming?
Thank you in advance!


texts:
I am working with adafruit RFID/NFC reader.

This reader works with a PN532 chip.

This chip is designed to read mifare tags (13.56MHz).

I want to read T5577 tags. This tags works at 125 kHz.

I am wondering if PN532 chip can read this tags. I have tried with an Arduino and PN532 library but it does not work.

I want to know if this is a software issue or if PN532 can really not read 125 kHz tags.

If it works with 13.56Mhz, it should work with 125khz tags ("who can do more can do less")

Thanks


texts:
I have been learning about the AVR sleep modes as I would like to start using them in my future projects. I think I have understood the most of it except some specific details below

Under Power Reduction Register (PRR), it mentions that using this to turn off the clock to a peripheral freezes the peripheral in it's current state with the I/O registers becoming inaccessible. Also the resources used by this peripheral would remain unoccupied. So its suggested to disable to peripheral before stopping the clock to it.
Under AVR-gcc documention of , they have provided the atomic instructions (sleep_enable, sleep_cpu and sleep_disable) besides the all automatic sleep_mode macro. The reason given is that sleep_mode might case race condition in some cases.

Can someone please explain the above 2 points in more detail.

Thanks!


texts: Voltage detection / Universal uC Input => CLD, PTC

texts:
I'm currently developing a open-source "Home-PLC" for home automation. Every thing runs fine so far and I have a module with fixed voltage AC inputs and outputs.

In the next step I want the build 'universal inputs' (power detection @ AC/DC 5..250V).

So I looked around and made some tests and have found a circuit that does what I want.
But unfortunately I don't understand the circuit and I also don't know a part (??) in the circuit.

I exchanged the optocoupler with a LED and used inputs from 5 VDC to 230 VAC. The LED just works with almost the same intensity.

Text on the part "??" is MZ3. That is normally a PTC (Thermistor).
The part has a resistance of 2.8 kilohm at room temperature. When holding the part tight in my fingers, resistance goes a bit down to 2.75 kilohm. Holding the solder iron close to the part the resistance is going down even more.

No idea how a PTC should work here!

Another thought was that the part is a CLD (current limiting diode).
But CLDs normally are looking like diodes an not like this part:

(??-Part)

Any ideas what the "??" part is?
How does the circuit work?
Any other ideas to build a "universal input" for less money?


texts: RS422 - Hot swapping - fuse blowing up - tvs?

texts:
I have an issue with the following schematic:

When I am doing a hot swapping on the RS422 (Local console) connector X1200, my fuse F1200 blow up. I have a TVS diode to protect against overvoltage on power line (+36VDC) against ESD. However I don't have TVS diodes on Tx, Rx, gnd lines. Can it be the issue ? How could I prevent my fuse F1200 to blow up if the user is doing a hot swapping ?
I already check the fuse sizing and the typical current used is about 1 A, so it can't be a fuse sizing issue.
Additional information: VSL is +36 VDC and its power coming from an external power supply. This power is sent directly to pin 6 of connector X1200 in order to power supply an external circuit which is a console (containing a display unit, touchscreen, ssd.... (small computer)). This power supply is received by the external circuit then buffered. In the following picture you will see reception of the power supply by the external circuit.

Thanks  for your help,
Regards,


texts: Do the test operator must hold an antena during the EMC immunity test?

texts:
We are doing EMC test the Capacitance sensing Touch panel, pursues immunity issues versus 28MHz noise. We do it in 2 methods:

(1) The operator is holding an antenna(which generated 28MHz noise), and simultaneously touch the panel to test sensing behavior.
(2) The operator is holding an antenna(which generated 28MHz noise), and another people go to touch the panel to test sensing behavior.

As a result, noise level monitored in method (1) is by far higher than in method (2) and  it could not report relevant sensing behavior.

I want to know by what mechanism that noise transfer from antenna to the panel though human body when test operator is going to touch the panel?
In general, should the operator hold the antenna during test sensing behavior?

Thank you in advanced.


texts: Shift registers(?) failing after being left on a while

texts:
Resolved: SLCLR on SN74HC595 was not tied to VCC, so behavior was inconsistent.

I have a custom built board that is running seven 7-segment displays, multiplexed using SPI from an 5v Arduino Pro Micro.  It's a simple device to track/display time for a kids game.

On the high side, I am using a ti 74HC595 to drive IMD10AT108 NPN/PNP (transistor pair) driver chips.

On the low side, I am using a STP08DP05MTR (shift register based) LED Driver.

When I first build a board it works great.  100% functionality.  However, if I leave it plugged in running for a few days, something clearly gets fried.  When it's first powered on, it will work for about 4 seconds, after which the 7-segment displays go out...sometimes with a quick flicker.  They refuse to turn back on unless I physically cut power to the board...after which they will turn off again after a couple seconds.  An arduino reset is not enough to get the LEDs to light...hard power reset is required.

Now, if in setup(), I shift out a single display to light (and not shift out anything more data after), that LED will stay lit without issue, leading me to believe the issue is related to either the 595 or LED Driver shift registers.  Could also of course be the transistor based IMD10AT108 drivers, but I think keeping a static display lit points me in the direction of the shift registers.

Other than those components, I've got the required resistors for the LED driver, a .1uF cap next to the VCC pin of each chip, and a 10uF cap (I'm not sure it helps anything) where the power enters the board.  I power everything off VCC of the Arduino Pro Micro, sourced through USB.  There is also an IR receiver on the board to control the timer, but I can't see how that could be related.

I'm an experienced software engineer just learning the hardware side of things.  I have built two boards...and the exact same issue has now happened to both boards.  They are "toaster oven smd", so it's hard for me to pull and swap components.

The problem seems custom board related, and not hardware damage on the arduino. First board developed this problem after a week. I used the same arduino on the second board after the failure of the first board, and that second board worked fine for a week as well...before, after a week, that second board developed the same problem as the first.

Thank you for any ideas.


texts:
Given an array of N elements, element is M bits vector. I am going to sum them up.
For example, given an array of 12 bits vectors.
type data_array is array (integer range 0 to 68)  of std_logic_vector( 11 downto 0); --69s 12-bits-vectors

To sum up, I use two loops:

first loop: create an array  data_array_sum_1 of 6 elements: sum each 10 vectors ( 10 * 6)  + sum 9 vectors up.
second loop: sum 6 elements up,  data_array_sum_2

data_array_sum_1 will be created as:
 type data_array_sum_1 is array (integer range 0 to 6)  of signed ( 11+3 downto 0);

I add log2(10)=3 additional bits.
data_array_sum_2 will be created as:
 type data_array_sum_2 is  std_logic_vector ( 11+ 5 downto 0);

I add log2(6)=2 additional bits to  data_array_sum_1. data_array_sum_2 is the result of addition of 69 elements.
If I don't use loops and sum them up, I should add log2(69)=6, that means the result of addition of 69 elements are 18 bits vector.
I think, I should get the same length of the resultant vector and the length doesn't depend on the algorithm of addition, right? Have I mistaken?
EDIT 1
I am checking different options to sum up two std_logic_vectors. I have read in this forum you suggest to use signed or unsigned type to add them.
My design file:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

entity test is
port (
    a       : in std_logic_vector (11 downto 0);
    b       : in std_logic_vector (11 downto 0);

    result1 : out unsigned (12 downto 0);
    result2 : out std_logic_vector (11 downto 0);
    result3 : out std_logic_vector (11 downto 0)
);

end test;

architecture Behavioral of test is
signal f: std_logic_vector(12 downto 0);
begin
    result1 <= '0'& unsigned(a) + unsigned(b);
    f <=  std_logic_vector(unsigned(a) + unsigned(b));
    result3 <= f(12 downto 1);
    result2 <= std_logic_vector(signed(a) + signed(b));

    --result3 <= std_logic_vector(('0'& a) + ( '0' & b));
    --result3 <= std_logic_vector(resize( a, a'length+1) + resize(b, b'length+1));

end Behavioral;

My test bench file:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

ENTITY testtb IS
END testtb;

ARCHITECTURE behavior OF testtb IS

    COMPONENT test
    PORT(
         a : IN  std_logic_vector(11 downto 0);
         b : IN  std_logic_vector(11 downto 0);
         result1 : OUT  unsigned(12 downto 0);
         result3 : OUT  std_logic_vector(11 downto 0);
         result2 : OUT  std_logic_vector(11 downto 0)
        );
    END COMPONENT;

   --Inputs
   signal a : std_logic_vector(11 downto 0) := (others => '0');
   signal b : std_logic_vector(11 downto 0) := (others => '0');

    --Outputs
   signal result1 : unsigned(12 downto 0);
   signal result2 : std_logic_vector(11 downto 0);
   signal result3 : std_logic_vector(11 downto 0);

BEGIN

   uut: test PORT MAP (
          a => a,
          b => b,
          result1 => result1,
          result2 => result2
        );

   stim_proc: process
   begin

       a <= "001001010001";
       b <= "110110101111";
       wait for 10 ns;
       b <= "001001010001";
       a <= "110110101111";

    wait;
 end process;

 END;

I found the correct answer gives result1. Then I have added result3 with f and smth is wrong with f.

ERROR: Array sizes do not match.

Why has it happend? I add two vectors, it means I have one additional bit.


texts: LT4363 High surge stopper shutdown at start up

texts:
I was asked to protect a DC/DC Buck converter against overvoltage and overcurrent event. During my research, I found the LT4363-2 component from Linear Technology that is defined as a High Voltage Surge Stopper with Current Limit. After reading its datasheet, I concluded that this component would do the work, would do what I was looking for.

The DC/DC converter is a [12V - 36V] Input / 12V Output buck converter (120W).

The nominal input voltage of the system is VIN = 28VDC. My problem is that when I turn on the system at its nominal value (28V), the system doesn't work : I don't have 12V at the output of the Buck converter, the LT4363-2 seems to be under protection fault. However, everything works fine if the input voltage when I turn on the system is between 12V and 19.5V. In this case, when the system is on and can supply supply the load, I can increase the input voltage up to 28V without having the system shutting down.

Here below my schematic :

simulate this circuit – Schematic created using CircuitLab

So :

\$ D_1\$ protects against reverse polarity connection.

\$R_{11}\$ and \$R_{12}\$ create a voltage divider. Their value are chosen so that the voltage seen by the UV pin is equal to 1.275V when the input voltage is equal to 9V. Thus, when \$V_{IN} < 9V\$ the system can't supply the load (undervoltage condition).

\$D_{2}\$ will limit the \$V_{IN}\$ voltage to less than 63V.

Since the minimum required voltage at the VCC pin is 4V, \$R_{10}\$ is chosen so that when \$V_{IN} = 9V\$, \$V_{CC} = 4V\$ at least.

\$C_{10}\$ is here to filter high transients up to 250V with a pulse width less than 300us.

\$R_{2}\$ and \$R_{16}\$ create a voltage divider to adjust the output clamp voltage value. Their value are chosen so that the output voltage clamp is 35.5V.

\$R_{9}\$ is a sense current resistor. It is chosen so that when \$I_{OUT} > 12.5A\$, the voltage seen between \$SNS\$ and \$OUT\$ pins is equal to 50mV leading the a overcurrent condition.

\$C_{11}\$ is chosen so that the N-MOSFET turns off after 310ms under overvoltage condition, and after 61ms under overcurrent condition. This value also set the cool down time (when expired, the MOSFET turns back on) to 18.83s.

I have checked multiple times my calculus and I don't understand where the fault may be. Right now I do not have access to the system so can't make complementary measurements. But with what I just provide for the moment, is anyone have an idea about my issue ?

Thanks !


texts: Eagle 6 : Problem Importing Custom Parts

texts:
Recently started working on a new PCB board for a dev kit. I ran in an issue where I had made a custom part for the M50-3501042 2x10 male header with 0.05'' (1.27mm) pitch.

Note also that this is a through-hole component.

The issue I had was that I set the diameter of each of the pins in the custom package to 0.04'', however, when I imported the part into my PCB design, the pins on the board had increased in diameter and were overlapping with other pins giving DRC errors.

I updated the library and all the parts in Eagle, however, this did not fix my issue.

I have no idea on how to fix this issue. Any ideas?

EDIT: Okay so I tried the solution posted in the comment, however it did not work for me. Only the via holes on the board changed and not the pins on the custom part. I tried messing with some other DRC settings but haven't been able to come out with a solution yet.


texts: LED bulb still emits light when turned off

texts:
I have recently purchased an IKEA LED bulb with G9 fittings, to replace a halogen one. This one.

The bulb is installed in a lamp with 3 other halogen G9s in a 3 + 1 configuration with a 3-state switch. "up" lights up all four bulbs, "down" lights up only the socket where the LED is.

I have found a strange behaviour. When the lamp's switch is in the off position, the LED bulb still emits a very dim light, whereas the halogen ones do not.

What is happenning here? Is this normal?

From my limited knowledge I would guess the lamp's circuit has some residual current which is not enough to light up the halogen bulbs, but makes the LED emit the dim light observed.


texts:
I am a hobbyist looking to buy a soldering station. The market for soldering equipment ranges from $10 to $1000.

This begs the question:
 * What is the reason behind these huge price differences?
 * What attributes should I look for in a good soldering station?

I researched a bit and found out that a good soldering iron should be temperature controlled and should strive to pump enough wattage to maintain the desired temperature while the soldering iron is tranferring heat to the component it's heating.
Additionally it should be a brand that has easy to find replacement tips.

Surely there must be other things that I am unaware of. Please shed some light on these unknown unknowns.


texts: Can I wire 1 more bluetooth antenna to extend the range?

texts: I want to extend my bluetooth range for my Sony Playstation 4 to be able to play in different rooms. I have added an external antenna by taking off the original one and replacing it with a removable one. Unfortunately it wasn't enough and the signal is still not as good as I would like to have. My next thought is to put 2 antennas on the same wire and put them in different rooms. Will it work? Won't the signals transmitted by the 2 antennas interrupt each other?


texts:
More and more frequently I am faced with a specification that requires the ability to discharge an output capacitance to a safe level X, in time Y. The circuit I am currently working on is 2000uF @ 600V (roughly 300J). It needs to discharge to 30V in 2 seconds. I can accomplish this with a few resistors and a FET in series with an average power dissipation of 180W over the 2 second discharge time, but I feel like there is a better way.

Does anyone know any alternative active discharge methods?

Thank you


texts: OrCAD PSPice less than 2 connections error while simulating

texts:
I just started using PSPice and I don't know much circuits theory but I need to simulate this circuit and find Vout/Vin:

I did this using capture but after running simulation I get this error:

  Less than 2 connections at node N01198

node N01198 is one of E1 nodes (I suppose I had to use a Voltage Controlled
Voltage Source but I'm not sure). Also I changed the GAIN of E to 100000, does that work?

I tried reconnecting wires differently but it doesn't stop the error. also I don't know which type of simulation I have to try to find the frequncy response Vout/Vin.
Can someone help me please I'm so confused.

my schematic:

I'm using PSPice 9.2.


texts:
First of all, i am a software developer, and understand very little of electronics.
I'm planning to build a hexapod robot with the micro tower pro sg90 servos, controlled by the arduino mega. In the end, 18 servos will be used (3 for each of the 6 legs). Knowing that every servo draws about 150mAh at peak, and they work at 5V, do i need a battery that provides 2,700 mAh? Or i can work with a battery that provides less than that?

What kind of battery should i use, since there's no 5V battery? I can use a LiPO which is 8.4 V, is there a way to convert this voltage to 5V?


texts: What does Dominant pole/Pole mean related to capacitors and filters or Electronics in general for intuitive understanding

texts:
I am trying to understand the feedback compensation techniques of DC-DC Buck converters. And I drift to more and more small questions which make me want to understand the basics of poles/zeroes/frequency
In this link the answer given by user Kaz, in the last para, "One way in which amplifiers with multiple poles are stabilized is with the help of capacitors which create a "dominant pole" whose frequency roll-off is so great that the poles at higher frequencies basically do not matter (the gain is squashed at those frequencies). The amplifier basically "looks" like a single pole one."
I can't able to understand what he is saying in the last para. I know, it is somewhat easy. But i am not able grasp
In general, can someone clarify me the concept of pole, dominant pole with filters/capacitors?
Like, if someone says, there is a pole in the feedback loop, or two poles in the loop, how to understand it electrically? one more question regarding this, i understand that if there is a pole, it means that oscillations will be present in the system. But the oscillations will be at what frequency? Will it be at the resonant frequency of the part or the entire systems?
Experts who find mistakes in my question, please let me know where I am wrong.
I also find a single pole and double pole loops. How do they arise?
It would be better if someone can provide me an analogy regarding these poles/frequency for good understanding.
Thanks.


texts:
I have a RF signal up to 50 MHz coming from a VCO which I want to use on a different impedance circuit. Without any adaptation the signal go down quickly when i raise the frequency because my load is capacitive (it's a sort a capacitance meter).

So I try to find the good operational amplifier to make a voltage follower in order to adapt my VCO output with my circuit. But I fail to obtain good results, I'm still a student so my knowledges are limited.

My adaptation circuit :

I've read that a small resistance as 50 Ohm can help with capacitive loads. But I'm searching for the right amplifier, I've found this one :http://www.farnell.com/datasheets/1808735.pdf and my VCO is a TEXAS INSTRUMENTS  SN74S124N

What parameters are important in this case ?


texts: Which programmer/connector can I use for a 6 pin header on mechanical keyboard design?

texts:
Forgive me, I am not an engineer but I wanted to figure out which connector I should use to program my custom mechanical keyboard design. The PCB has an Atmega32u4 controller which is connected to a 6 pin header.

I am adding more detail to my question because other members requested it so they understand my question better. I used to make custom keyboards using QMK plus Adafruit feather boards and it was easy to program them because I can just plug in a usb cable and get started.

Now, I am trying to learn how I can program a controller like the Atmega32u4 directly on the PCB. My friend helped me design the PCB and but I didn't get a chance to ask him everything about the design. I did some research and found that the 6-pin header on the PCB board is how I can program the controller. I can easily solder the header but I don't know what to do after that. I assume there is some sort of connector or cable I should be using. Thanks in advance!


texts: How to change the led on this board to a brighter led? 12v input

texts:
Needed to change these led to brighter led. Is it possible?

If yes then how can it be done?

Noobie!!


texts: Elliptical board edges in KiCAD or CircuitPro?

texts:
I am trying to use KiCAD to design a PCB which must fit into an existing case. One side of the PCB needs to be shaped as a specific elliptical arc segment. I can figure out the parameters of the desired ellipse, but I do not see how to actually draw such an Edge Cut in KiCAD.

Is this possible in KiCAD, or am I using the wrong software for this? The board will be made on LPKF ProtoMat, so I'll be using CircuitPro software to create the final instructions for the plotter (don't know how that works yet).

So my questions is whether I should be thinking about design of the board shape in KiCAD, or leave it until a later step?

Thank you.


texts: Running 3.3V MCU from LIR2032 Lithium-ion button cell

texts:
Background

I wish to power my circuit with a Lithium-ion battery LIR2032 (around 40 mAh capacity). These batteries have a voltage that goes from 4.2V to 3V typically during their discharge cycle.

My circuit (running at 3.3V) has a maximum current requirement of around 20mA -- although I should state that this is only the peak draw occurring in less than 0.1% of the time; the circuit draws below 1uA the remaining 99.9% of the time. It will be a sensor node which every 30s wakes up and emits data using nRF24.

Question

What would be the best way to efficiently convert the (changing) output voltage of a Lithium-ion battery to less than 3.6V which is required for the MCU?

Efficiency is very important here, because of very limited capacity of the battery.
Also I have no problem with varying voltage because the circuit can work with 3.0 or less, so it does not have to be precise 3.3V or similar, just need to be below 3.6 at all times.

EDIT:
I come to an idea, I can find MCU which is capable up to 5.5V (so it can work directly from battery). So only for nRF24 module lower voltage is required. Please look at schematic. What do you think?
The idea here is to turn on transistor only when required (transmitting). And even base current is used so only losses are in transistor (for voltage dividing).

simulate this circuit – Schematic created using CircuitLab


texts: While loop in test bench of and gate. getting no output

texts:
I have written a simple test bench for and gate. My code and test bench was working fine. Now what I want to do is " I am trying to implement a while loop for my cases". I am not getting syntax error but not seeing any output. can any body tell my mistake?.

timescale 1ns / 100ps

int count=0;
module and_gate_test;

// Inputs
reg in1_t;
reg in2_t;

// Outputs
wire out_t;

// Instantiate the Unit Under Test (UUT)
and_gate and_gate_1 (in1_t,in2_t,out_t);

initial
begin
    // Initialize Inputs
    //case 0
    while(count==100){
    in1_t <= 0;
    in2_t <= 0;
    #1 $display ("out_t=%b",out_t);
            //case 1
    in1_t <= 1;
    in2_t <= 1;
    #1 $display ("out_t=%b",out_t);

    //case2
    in1_t <= 0;
    in2_t <= 1;
    #1 $display ("out_t=%b",out_t);

    //case3
    in1_t <= 1;
    in2_t <= 0;
    #1 $display ("out_t=%b",out_t);

   count++; }
    // Add stimulus here

end

endmodule


texts: Replacement for tube-based trigger switch (Thyratron) in high-voltage supply

texts:
A now-deleted question asked whether it's possible to replace the trigger in a specific application (laser supply, source here):

and other things.

For me, it boils down to a single, less application-specific question:

why is it hard to replace tube technology which was introduced in the 1930s with semiconductors in high-power, high-voltage applications?


texts: Two TPS5430 inverting buck-boost converter modules failed in a row, am I using them wrong?

texts:
I've bought three of these inverting (negative voltage) DC-DC converters. I'll include hi-res images of the module's PCB at the end of my question.
Two of the three failed in a row during initial testing from a bench power supply, and now I'm afraid to even power on the third one because I really need it working for my project.
The first one: connected it with no load (only a DMM for reading Vout), slowly went through input voltages from +5.5 V to +11.9 V. Output is steady -12.2 V. As soon as I went 0.1 V higher (either 11.9->12.0 or 12.0->12.1, don't remember exactly), there was a pop, a spark, and the magic smoke came out of the small 4R7 inductor. Now the module's input is almost shorted (not exactly 0 Ohm, but a very small input resistance).
The second module: I thought maybe some load is required for normal operation, so I connected a small 3-digit LED voltage meter module, about 12 mA current draw at 12.2 V. This module survived going over +12 V Vin, I tried up to +17 V. Then I left it on at +12 Vin and looked away for a minute or less, when I returned - it was fried just as the first one, except there was no smoke nor a spark.
I did some searching online and found a TI application note for building a TPS5430 inverting buck-boost converter. I don't see any usage limitations that I might have broken when testing my modules, but also, the TI circuit has a single inductor and my PCB has two of them so they're not an identical design.
Do you have any idea why two out of two modules the I tested died almost immediately with small load or no load, and whether I can do anything to keep the last remaining one alive and working with 0-100 mA of output current?
Photos of my regulator PCB:


texts: This must be an absolute naive question, but I’m going to ask it anyway. Aside from the obvious thermodynamic law violation, if I short cut a resistor’s terminals, why doesn’t thermal Nyquist noise in the resistor produce heat and raise its temperature until it burns up?


texts: Add iPod 4 dock to old Hi-Fi (Will my idea work?)

texts:
I'm currently attempting to add an iPhone Dock to my old Aiwa Hi-Fi system. I've used a multimeter and established that the VCC for the Hi-Fi's internal circuitry is 4.83V.

I've used information from Pinouts.ru to come to the conclusion that the pin connections should be:

1: GND
3: R-out
4: L-out
11: GND
15: GND
21: 1K ohm - GND
23: VCC
25: 2.8V
27: 2V

So firstly, have I understood the resource correctly, and is it okay to float the unconnected pins?

Secondly, I'm going to get the 2.8V and the 2V using potential divider circuits from VCC to GND. Are these resistor values appropriate?

2.8V: R1 = 43K  | R2 = 56K

2V: R1 = 56K |  R2 = 43K

Oh, and one final thing I would like to ask, and this may seem really simple but I should probably check! If there is a connection on the PCB labelled AGND, can I use that as GND?


texts:
I've an old device whose circuit is fried somewhere but since I want to modify this device, I don't want to find which component is fried, I simply want to plug it my own power supply instead. Luckily I have a second working device to test voltage and current wherever I want.

This device has a tiny coil activating a switch when current passes through it so I desoldered the wires on the working device to test this component. I tested both in DC and AC mode, here are the results:

Resistance: 64 Ohms
Voltage:

OL (DC)
2.1 V (AC)

Current:

Entering the coil: 177 mA (DC) and 31 mA (AC)
Leaving the coil: 177 mA (DC) and 31 mA (AC) then slowly lowering to 30 mA (AC)

My question is: Can I deduce for sure this is an AC coil requiring an input of 2.1 V and 31 mA?

Also I know that assuming this is an AC coil I should in theory be able to input DC current as well. This way would be much more convenient since phone chargers or other kinds of everyday life transformers are often providing DC current.

So what would be the input power like if I choose to input DC instead of AC (assuming this coil is really an AC coil)? Is there an easy way to calcule the voltage and current I should apply?

EDIT: Additional information about the coil

Here is a photo of the coil. When a current passes through it, a magnetic field is created therefore attracting the metal plate. When this happens it activates a mechanical system which uses rotational energy from a 230V AC motor.


texts: I have an MZ4 thermistor, I can't find info about the value of capacitance

texts:
I have bought a self assembly kit for power source (based on the LM317). The provided small thermistors are tagged as MZ4. I did my research but couldn't find the datasheet. The PCB is showing them to solder in place of 0.1uF capacitors.
How does a thermistor become a capacitor?
In future encounters of thermistors how do I know their capacitance? (I have no measurement gear besides a multimeter.)


texts: The reading distance limit on passive RFID

texts:
It appears that nearly all "passive RFID" tag-reader combinations have around a 5-10cm specification for reading distance.

But I am interested in approx. 20 cm reading distance.

I am assuming one of these is the right approach to follow, but I'm not sure which:

Perhaps the 5-10 cm range is a constraint of the passive RFID technology itself, and I should look into other technologies?
Or is it that there exist variants within the passive RFID technology (and the frequency band within which they operate)?
Or should I look into different kinds of tags specifically (I highly doubt this is the case since they do after all transmit upon being energized by the reader)?
Or should I consider adding a specific external antenna to my RFID reader?

Note: I am aware of "Active RFID", but given its battery requirement on the tags, this is not ideal for my experiment.


texts: Connector type for a plug-in short-circuit

texts: I am looking for a product, type of a connector (2 pin, panel-mount) that also has a something to plug into it which will short-circuit the two pins. Is there any name for such a connector? (or only the short-circuiting plug)


texts: Can I provide a negative input voltage to this (or any) ADC?

texts:
I have a pH probe which is a high impedance voltage source of which I want to measure in increments of 0.5mV (500uV) with an ADC. This voltage can swing between +/- 1V.

I have chosen this ADC as something that looks suitable for the job: http://docs-europe.electrocomponents.com/webdocs/0d2a/0900766b80d2a9fd.pdf

When placed in 14 bit resolution it should give me 250mV per LSB, more than I need - but that's okay.

Now I'm unsure if I can feed my -1V signal into this ADC, as in all the diagrams it shows VSS tied to GND, not a negative source (like an Op Amp). I expect I can't tie this to a negative source because of the I2C output which would swing negative? <- Just a guess.

Can anyone help me understand if this will just work as described?

Edit: I realize I can bias the pH probe with 1.024V which will put it precisely in the middle of the reference voltage for the Op Amp, but I was hoping to make use of the Gain function of the ADC in certain situations, but if this solve this problem I'm happy to do that.

Many thanks.


texts: How do cheap Raspberry CSI-2 cables get around differential impedance matching

texts:
I am trying to design a circuit on (double sided) flex PCB that happens to have CSI-2 signals on it.
I would like to find out what is wrong with my deductions presented below, or what part of differential signaling have I misunderstood.
When I tried to calculate the trace widths and spacing, given the parameters of Flex PCB (extremely thin), It seems difficult or at most impossible to manufacture. On top of that, Polyimide and adhesives have only approximate dielectric constants available. (I am not working with controlled impedance Flex PCB)
But I realized, that FPC cables are used all the time in Raspberry (and almost all, camera modules and interfaces).

Since they are single-sided, I thought that they get around impedance matching by placing the ground next to the differential traces.

After a quick check on some online impedance matching calculator, I came to believe that those ground conductors adjacent to pairs of differential pairs have nothing to do with impedance matching at all. (so are those just to reduce crosstalk?)
I do realize that differential pairs theoretically do not need any ground plane — and that it just provides shielding and reducing crosstalk. But I always believed that those are absolutely mission critical aspects and I never really wondered (up until I faced this PCB design) that it never really was the case?
Are my deductions correct?
Should I just delete the ground plane under the differential pairs on my flex PCB and call it a day?


texts: How many newtons are there in one coulomb of charge?

texts:
Or, I should have said, how many newtons of force does one coulomb of charge exert? At a distance, presumably, of one meter?  Since N/C is supposedly equivalent to V/m?
P.S.  What are the values for a single electron or proton?  The 'elementary charge'?  I suppose it would be the answer(s) to my first question divided by 6×10-19 .....


texts: Replacing 75 ohm heating coil with resistors?

texts:
I am trying to remove the thermal fuse, thermostat, 75 ohm, and 150 ohm heating elements from this diagram:

This is the schematic for a popcorn machine that has two heating coils and a DC fan to blow over the coils: http://www.sweetmariascoffee.com/forum/viewtopic.php?f=14&t=5761.  Basically I am trying to create a 115 V AC circuit that powers the 18 V DC motor through the rectifier bridge.

I imagine I need to replace the 75 ohm heating coil with some kind of resistor for this circuit to work correctly.  Can I simply replace the 75 ohm heating coil with 75 ohms worth of resistors that I typically use in my DC only circuits?


texts: What is the series resistor doing between the power source and the power input of this IC?

texts:
This is from an Adafruit RTC module.

What purpose is the R3 1k resistor serving in this circuit? Is this a RC charging circuit? Would the capacitor C1 not get any charge if the resistor wasnt there? How is the value of R3 determined?

Thanks!


texts: Controllability and Observability of a Circuit through State Equation Inspection

texts:
In Kalman's 1963 paper "Mathematical description of Linear Dynamical Systems" he introduces the concepts of controllabilty and observability. In the first example he builds a constant resistance network where we have
$$\frac{L}{C}= R = 1$$

and develops the systems equations choosing $$x_1 = \phi_L :\ \text{magnetic flux in the inductor}$$ and $$x_2 = Q_c:\ \text{capacitor eletric charge}$$
\
After some simple circuit manipulations we get the system's state equations as
$$\dot x_1 = -\frac{1}{L}x_1+u_1$$
$$\dot x_2 = -\frac{1}{C}x_2+u_1$$
and output equation as
$$y_1 = \frac{1}{L}x_1+\frac{1}{C}x_2+u_1$$
After that, he changes the state and output equations through an equivalence transformation
$$\overline{x}_1 = \frac{x_1+x_2}{2}$$
$$\overline{x}_2 = \frac{x_1-x_2}{2}$$
and so we get another set of state equations
$$\dot{\overline{x}}_1 = -\frac{1}{L}\overline{x}_1+u_1$$
$$\dot{\overline{x}}_2 = -\frac{1}{L}\overline{x}_2$$
and another output equation
$$y_1 = \frac{2}{L}\overline{x}_2+u_1$$
Question: Why the system is uncontrollable and unobservable if in the first set of equations the input u is affecting both state variables and they're also present in the output equation? I see that when Kalman changes the system state and output equations, it becomes clear that
$$x_2\ \text{is uncontrollable}$$
$$x_1\ \text{is unobservable}$$
but I coundn't see that looking at the first set of equations.


texts: Disconnecting a resistor out of parallel with a switch

texts:
I'm modifying an existing circuit. In order to perform this modification, I need to tap a resistor in the circuit and put another in parallel. By connecting this resistor in parallel (changing the resistance of the existing resistor) it will alter the circuit. Removing it, puts it back the way it was.

My question is this: If I connect the resistor to a switch, do I need to disconnect both legs of the resistor to remove it from the circuit or only a single leg (double pole switch vs single pole switch)? Is it relevant that this resistor is in a motor circuit that may have sine wave frequency running across it?

Thanks!


texts:
Kirchhoff's law states that “in any closed loop network, the total voltage around the loop is equal to the sum of all the voltage drops within the same loop”

What would happen if you placed a LED with a 2V drop into a circuit with a 12V battery and no resistor, would this work as it breaks Kirchhoff's law? and how would you calculate the current in this circuit?

Then, if you swapped the 12V battery with a 2V battery, what would happen as this is now in line with Kirchoff's law? what would the current be in this circuit?

Thanks.


texts: What do I need to do the following things with an arduino?

texts:
I need to do the following with an arduino board:

Drive something at a power higher than that of the usb, like max 50W. I guess I have to use analog output and then amplify the signal somehow, but I don't know how.
Do the opposite too, I mean safely measure a signal if it is even at 50W, without frying the arduino in the process.

As you can guess I'm a newbye, so please be patient.


texts: Why do Class AB amplifiers use a pair of diodes instead of a resistor?

texts:
I understand that in a Class AB amplifier, a pair of diodes are placed between the bases of the two transistors to slightly forward bias both bases.

Why are diodes typically used to provide the forward bias instead of a single resistor providing a voltage drop of 1.2V? (Is it because changes in temperature will affect the forward bias of the transistors and the diodes in roughly the same way?)


texts: Looking to source alignment studs for circuit board

texts:
I am building a completely custom tube amp with two amp boards (L & R) that slide in and out of a wooden case I've made.

I am having trouble sourcing a specific component.

I'm not really sure what they are called, but it's an alignment stud used to align and ground the board prior to inserting the board all the way in the chassis.

Iv'e attached a picture of a Dell Poweredge M610 Motherboard with the studs in question circled in red.

Anyone have an idea on where something similar could be sourced? Thank you ahead of time.


texts: Why can an oscilloscope only find frequencies 1/10 of the sampling frequency, despite Nyquist?

texts:
The oscilloscope at my university states both its sampling frequency and the maximum frequency that it can detect. However, the maximum frequency is just 1/10 of the sampling frequency! Nyquist's theorem states that all frequencies up to half the sampling frequency can be reconstructed.

What kind of problems are the oscilloscope constructors expecting?


texts:
The collector of the IR Reflective Sensor is connected to 3 V via 100 KOhm resistor. The Anode of the diode is connected to  3 V via 10 Kohm resistor. Both Emitter and Cathode of diode are connected to Supply return.
Kindly refer to data sheet below.

As per my calculation the collector current will be only 30 uA. Is that collector current sufficient? The Collector of the photo transistor in the sensor is directly  connected to a MCU input pin(Maximum leakage current of 1 uA)

Part Information: QRE1113GR
Datasheet:Here

Edit:

Maximum detection of Pulse is 800-900 RPM


texts: Open circuit stub or short circuit stub?

texts: What are the respective advantages of using either an open circuit stub or a short circuit stub?


texts: I have to control some device which require minimum 40mV/uS as slew rate for ENABLE input. My mcu runs at 3.3V so the rise and fall should be faster than 82.5uS. This is correct? Does it matter the actual speed of MCU?


texts: ICSwitching between solar panel and batteries

texts:
I would like to charge the NiMH batteries, when there is excess power from the solar power and use the power stored in the batteries, when I need it (to drive a motor and at night). I have the following circuit:

IC1: LM317
IC2: LM7805

On the right side, there is a uC, which needs to be powered all the time (through day and night) and drives a heavy load (motor cca 2A) for a while once a day.

The problem is, that I am not sure how the circuit will behave when there is power from the solar panel (SOL+ and SOL-), but it might not be enough to drive the motor (which will be connected to the +18 line) - ideally the voltage should drop and the MOSFET Q1 should open, supplying the motor power from the batteries. But I am afraid, that the battery and solar voltages will get to some balanced state, leaving the MOSFET half open and frying it.

What is the common solution to this problem? Would simply changing the MOSFET for a diode solve it better? Also is the diode D2 needed (I put it there to stop the LM317 from trying to source current when powered from batteries).

Thanks a lot for your ansvers!


texts: How does the LM35 Temperature sensor work?

texts:
And I mean, how does it work internally, how does it output a voltage when temperature changes, etc. When I see explanations online, I don't understand much of how it works (supposedly something called a PTAT is involved).

Can someone explain it to me like I'm a total noob when it comes to electronics?


texts: Multiple Switch Equation to NAND Only equation

texts:
I'm trying to convert a regular Boolean equation that has multiple inputs into a NAND only equation. My guess is that I'm supposed to convert using DeMorgan's law, but I'm not entirely sure how to do that. The equation I'm trying to convert is (A&~B)|(C&D).
I've created a logic circuit that implements the regular gates and its NAND equivalent:

I also have the diagrams on how a NAND gate is used to create difference gates, but still not quite sure how to convert it to an equation. I'm trying to create an equation I can implement in Vivado (if anyone has experience with that). Is there a Boolean symbol for NAND?
Any help and direction would be greatly appreciated. Thank you all so much.


texts: What's the mechanism whereby the external device places a RST instruction on the bus, along with an interrupt # 0-7? I only know that external device sends signal to INTR pin to interrupt 8085


texts: How dense is SRAM compared to random logic?

texts:
Modern CPUs always have some on-chip cache, typically more than one level. This takes a lot of die area; static RAM is generally reckoned at six transistors per bit.
That having been said, the preponderance of area taken by static RAM, is not quite what you would expect just from raw transistor count; such a regular structure takes less area per transistor than the random logic constituting the rest of the CPU.
Roughly how much denser is static RAM than random logic? Would it be approximately accurate to say that it typically takes half as much area per transistor, or a third as much?


texts:
simulate this circuit – Schematic created using CircuitLab

I have a circuit like the one in the image (plus a few more caps)

P1 on the MCU is a PWM pin, 270Hz frequency and 60% duty.

What I am trying to achieve is convert the PWM output from the MCU to a 12Volt open drain output.

According to my oscilloscope the voltage on the collector is about 2.2V (when it's ON). I would expect it to be closer to 0V. Any idea what am I doing wrong?


texts: What does a double edge in a timing diagram indicate?


texts:
i try to use the SDRAM on my DE0 Board.

This is the chip: http://zentel-europe.com/datasheets/A3V64S40GTP_v1.3_Zentel.pdf

Basically my driver works. i save the value of an upcounted signal in the memory during my initialization. Means that at address 0 there is the value 0 at 1 it is 1 and so on. After wrtining into the memory i read it out in an endless loop. this works fine, as long as i keep some delay between the single readouts. If the delay gets too short, i only get some garbage back.

I have connected an logicanylzer directly to my memory. But i cant figure out what makes the problem.

Here are some Pictures:

The picture above, shows a correct readout series. You can also see the RAS, CAS, WE lines. It looks good. and the values are correct.

This picture is with a delay of 16 Clock between each readout. If i decrease the delay to 15 Clock, then it looks much different.

The read out values are now just some random values. As you can see in the picture, there is no longer any upcounting value. But the RAS, CAS and WE lines are still correct.

The same picture if i sense the MSB Bit of the lower byte of the Data Word.
The yellow channel shows a new series of addr 0-255. The blue one shows the MSB of the byte.

I have searched for this bug for many days now and i have no more ideas where to search.

I really hope that somebody can help me figure out what is going wrong here.

Thank you in advance.


texts: Is there any relationship between sensitivity of rogowski coil and voltage rating of coaxial cable with it. For example if I just have the sensitivity of the coil and spec of coaxial cable, is there a way to calculate current rating of the coil?


texts:
I'm currently designing a PCB. One of the ICs I need to use is stated as being a "SOT-363 (SC-88)" part. In KiCAD, there is a footprint for a "SOT-363_SC-70" part.
What's the difference between an SC-88 and SC-70 footprint? I couldn't find a clear answer online.
Would I be okay in using the SOT-363:SC-70 footprint for my SOT-363:SC-88 IC?
Thanks.


texts:
I am building a circuit which communicates with an external Power Supply via UART. One of the IO pins from my MCU is connected to an optocoupler

I have 4 relays on my PCB, they are separated galvanically from the rest of the circuit, and powered from a separate power supply. The problem is, that I get a nasty spike on the UART line in the moment when one of the relays is operating. This is how it looks (measured in point TP4 on the schematic above):

How can I prevent this spiking? I tried adding 2 clamping (Schottky) diodes to the supply rails, the problem still exists. I have a large GND polygon pour over the Bottom layer, even under the mentioned relays (not connected obviously), does it affect my circuit in any way?

EDIT:
This is the relay drive circuit:


texts: How to create a 64 bit Carry Look ahead adder?

texts:
I am trying to implement the verilog code using generate statement.There is issue with taking four bits for calculating P and G values.Added the code below for reference.
Cin is taken as Zero.

`timescale 1ns/10ps

module cla_64bit(sum,c_out,a,b,c_in);

input [64:0]a,b;
input c_in;
output [64:0]sum;
output c_out;
wire [65:0]sum_out;
wire [64:0]c_in;
wire [64:0]c_out;

assign c_in[0]=1'b0;

genvar i;
generate
  for (i = 0;i<64;i=i+16)
        begin : FA
            add_16bit FINALBITBLOCK(
              .sum    (sum_out[i]),
              .c_out  (c_in[i-1]),
              .a  (a[i]),
              .b  (b[i]),
            .c_in   (c_in[i])
            );
          //assign g[i]=a[i] & b[i];
          //assign p[i]=a[i] ^ b[i];
          //assign c_in[i+1]= g[i]|(p[i] & c_in[i]);
          end

assign c_out=c_in[63];
assign sum=sum_out[63:0];

endgenerate
endmodule

module add_16bit(sum,c_out,a,b,c_in);
input [15:0]a,b;
input c_in;
output [15:0]sum;
output c_out;
wire [15:0]p,g;
wire [15:0]sum_out;
wire [16:0]c_in;
wire [16:0]c_out;

assign c_in[0]=1'b0;

genvar i;
generate
  for (i = 0;i<16;i=i+4)
        begin : FA
            add_4bit FOURBITBLOCK(
              .sum    (sum_out[i]),
              .c_out  (c_in[i+1]),
              .a  (a[i]),
              .b  (b[i]),
            .c_in   (c_in[i])
            );
          assign g[i]=a[i] & b[i];
          assign p[i]=a[i] ^ b[i];
          assign c_in[i+1]= g[i]|(p[i] & c_in[i]);
          end

assign c_out=c_in[15];
//assign sum=sum[15:0];

endgenerate
endmodule

module add_4bit(sum,c_out,a,b,c_in);
input [3:0]a,b;
input c_in;
output [3:0]sum;
output c_out;
wire  [3:0]p,g;
wire [3:0]sum_out;
wire [4:0]c_in;
wire [4:0]c_out;
assign c_in[0]=1'b0;

genvar i;
generate
  for (i = 0;i<4;i=i+1)
        begin : FA
            add_full FA(
              .sum    (sum_out[i:0]),
              .c_out  (c_in[i+1]),
              .a  (a[i]),
              .b  (b[i]),
            .c_in   (c_in[i])
            );
          assign g[i]=a[i] & b[i];
          assign p[i]=a[i] ^ b[i];
          assign c_in[i]= g[i]|(p[i] & c_in[i]);
          end

assign c_out=c_in[3];
assign sum=sum_out[3:0];

endgenerate
endmodule

module add_full (sum, c_out, a, b, c_in);
output sum, c_out;
input  a, b, c_in;
wire   w1, w2, w3;

add_half M1 (w1, w2, a, b);
add_half M2 (sum, w3, w1, c_in);
or M3 (c_out, w2, w3);
endmodule

module add_half (sum, c_out, a, b);
output sum, c_out;
input  a, b;
xor M1 (sum, a, b);
and M2 (c_out, a, b);
endmodule


texts:
So basically, I just recieved my LTC3108 breakout board and wanted to test it. The way it (supposedly) works is you solder two specific points on the board together to indicate a specific output voltage. You can see my two joints in the bottom right side of the board, which gives an output of 2.35v at Vout. If you look at my white led, it is set in Vout and my peltier is soldered into Vin. When holding down on the peltier, it doesn't light. The multimeter reads absolutely no voltage going into Vout. Does anything look wrong with my set up? Here is a link to where I bought it with info on its usage in the description.

https://www.ebay.com/itm/331654685113


texts: What is this capacitor for? What is its purpose in this circuit?

texts:
Esp8266 programming circuit is here. Could anyone help me identify the purpose of this capacitor?

Thanks in advance.


texts:
\$I_3=10*10^{-6}A \$ and \$ I_4=30*10^{-6}\$.

Then i want to calculate the \$v_0\$ .

By V=IR , I get \$200k*I_4\$= -6 V.

By voltage divider rule, \$\frac {40k}{50k}*-6V=-4.8\ \mathrm V\$ .

Can i understand that part like this below?


texts: Multisim - Circuit Design with a 555-timer

texts: I am currently working on a design project. I am trying to get my 555-timer to turn on (1-minute) a motor and LED when activated and then turn back off after the 1-minute has passed. I am taking the output of the 55-timer to a IRF520 (power MOSFET) to serve as a amplifier. This will allow enough current for the motor and the LED. However, I am not getting the desired results.


texts: Input voltage swing when starting a DC brushed motor

texts:
I am working on a circuit that include a H-bridge for a DC brushed motor. I am having problem when the system might run for a short period of time (5s) before the Micro-controller stop responding. I am suspecting that the noise from the motor is causing the corruption on I2C line or brownout due to voltage swing. Further inspection, I can see that the swing in the 12V rail is shown in all 3V and 5V rails. I don't know why and how would I isolate this swing to just the 12V rail or reduce the swing peak-peak?
System description:

Single GND, all power from a 12V battery that can handle 10A peak
12V ->5V buck regulator (47uF output cap) to step down voltage for micro-controller board Vin
5V-> 3.3V (unsure value of output cap) linear regulator for uC IC
470uF bulk cap + 0.1uF ceramic cap next to H-bridge driver, there is 3 more 470uF caps at further distance
Low power DC motor (1A at normal operation, ~3.6A starting)
H-bridge control is just on/off, no PWM

GND of Oscilloscope is at common GND point (where the battery is plugged in)
When measuring the voltage at the leg of the H-bridge capacitor, motor turn on give make the 12V voltage swing above and below 12V.
Voltage across the 12V cap

Voltage at 3.3V linear output

Voltage at 5V buck output


texts: Risks of using device body as heat sink for IGBT and Bridge rectifier

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I want to know is any risk factor (electrical shocking or ... ) for using one aluminum (4mm) device body which is used as heat-sink for IGBT and Bridge rectifier that are working with 220 volt power?
is use a silicon layer between those surface how is it? (guess withstand temperatures up to 260°C (500 °F))

thanks a lot.


texts: Why CAN bus impedence changes when I send data?

texts:
I have setup two chanels to send data from PC to micrcontroller. Both of them were working initially. Now one of the chanel does not work.
WHen I dont send any data, Impedence between Can-H and Can-L is 120 Ohm on both chanels.
WHen I send data, impedence of of the faulty chanel goes several order higher and status of CAN bus becomes passive.

My questions are

What does it mean "CAN Bus is Passive"?
Why does the impedence change when I send data?

I am using HI 3110 to interface can bus to micrcontroller.


texts: I work on a solar tracking project and in this project I have to charge my Li-Po battery to store power and use this power for supplying the system. For this problem, I searched for the li-po battery balance charging circuits and I found one. My problem is lack of time(deadline) and I couldn't be sure about this circuit's reliability. Could you give me advice or could you approve my circuit if it is proper.


texts: What type of monostable multivibrator is this?

texts: In the circuit description it said 4538b, but after googling the diagram of this IC, it seems there is no schmitt trigger on the input as it shows on the photo. Does CD14538BE work for this application. What is the best option? Thanks


texts:
So, I recently threw out a bag of random chargers I didn't think I was using anymore. Later I found that my Dremel charger was part of these. I did however save all the connectors and just threw out the adapters, incase this would happen.
From what I can identify on images of the 7750, it is using a 5v 1650mA adapter, where the outer shell of the barrel is negative and the core is postive. Well I thought this would actually be quite nice, as I could wire it to a USB-A and just use one of my many AC-DC adapters, powerbanks, USBhubs... to charge it. (I have tried it using an old 5.2v 2.4a ipad charger, and 5v 2a oneplus charger)
So I did this and the light on the Dremel does light up red as an indication of it charging, but it never reaches max capacity (usually indicated by a green light if my memory is correct, and just turns off after a while). Once the light disappears I can turn off the power and turn it on again and the red light appears and seemingly keeps charging. After 10 minutes the Dremel is able to turn on and I can use it for a minute or so before it dying out. Leaving it for a longer period does not change the time.
I have attempted to use a cheap USB current reader, but it does not show any information, as if the current drawn is too low or something. I'm a novice in the field and would appreciate any explanation to why this is happening (:


texts: Beagle Bone Black USB current draw damage

texts: When I first got my BBB I immediately tested it on my TV via HDMI with my mouse and keyboard pair (both through the same receiver) in its USB host. Without thinking I powered the BBB through my computer. The mouse and keyboard worked fine the first time and worked after a couple reboots the second time. Now the mouse and keyboard don't work at all. It just occurred to me that they are probably drawing to much current so I found a 5V/2.5A power supply to power the BBB and the mouse and keyboard still don't work. Could I have damaged the USB Host output? Or Is there current regulators on board to prevent this?


texts: How to build a DC push-pull voltage amplifier with transistors?

texts:
I have a digital 3.3V PWM signal that I want to send to a speaker, i.e.

amplify to higher voltage (e.g. 12V, but not sure)
and remove DC offset with a capacitor.

For the capacitor to work as intended, I think the amplification needs to be capable of sinking to ground.

After all I read, a push-pull amplifier should be doing the trick, but I don’t see how this can work without a negative supply rail. What are my alternatives?

simulate this circuit – Schematic created using CircuitLab

Since 12V > 3.3V, Q1 will essentially always be in saturation, thus in the configuration above, I’ll have a short circuit if Q2 is also in saturation.
If I exchange Q1 & Q2, then I won't have the voltage amplification any more, because as soon as C1 reaches 2.7V, the NPN transistor will be cut off. (And if it were not, soon after the PNP transistor would activate again.)


texts: Help replacing a physical joystick for motor control with a LabView program

texts:
I'd like to start by acknowledging the similarity of this question to this one, but I really need a more basic, step-by-step explanation.
I am trying to help a student in my lab design a program to remotely operate an instrument (necessitated by the global shutdown). The part of this instrument that needs automation is a motorized sample stage. The stage is moved by a motor controller which comes attached to a physical joystick that goes up/down/left/right by a fixed increment each time it is moved. The joystick also has the ability to switch between motors that rotate vs. translate, but that is a minor point.
My student would like to replace this joystick with a LabView program. Push "left" in the program, motor moves left one increment. What we need to know is: What hardware do we need to link a computer to the motor controller? Some specific facts/questions:

It has been suggested that all we need is a GPIO to USB device, such as those mentioned in 1, wired to the motor controller. Is this true, or do we also need relays or other equipment to connect to the GPIO pins?
Can we avoid using an Arduino or Raspberry Pi, or are these the best options out there?
Does hardware exist with prewritten LabView drivers? If not, I am capable of writing these or transitioning to python.
Are there any other things I need to be concerned about, such as installing fuses or resistors to mediate current? Safety concerns?

Any help you can provide is greatly appreciated, as neither of us have connected a device to a computer with neither predesigned cables nor software before. What would you do in our place, with a focus on safety, simplicity, and efficiency?
Edit: I believe our joystick is made by this company. Wires leaving each side of the physical joystick (corresponding to left, right, etc.) are connected to the circuit board of our motor controller. Neither the joystick nor the motor controller have any connections to a computer, serial cables, etc. It's all just plain wires and soldered connections, and a think the "circuit board" is mainly a series of resistors and connections to a voltage source, and has no programming, so to speak.


texts: Detecting very simple movements (a hand waving) usable on 8bits microcontroller

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Recently i saw a video about Nest Protect, an smart smoke detector, that can be operated by waving your hand under it. Since there is no visible holes on the lower part i suppose they are not using any light/acoustic sensors, like IR or ultrasonic, so it could be an RF type sensor, but i have no idea what specific sensor, do you know how they detect the waving of the hand with such a precision?, i mean, i can easily detect movement with a PIR sensor, but i have no idea how to reduce the range (if possible) in order to detect only near objects movements.

EDIT: I found this picture of the sensor, they are actually two, one vertical and the other one inclined, seeing the picture can you tell what sensor type is?