texts: Simple high frequency (GHz) RF radiation detector

texts:
I want to build a simple RF radiation detector that shows if there are any RF devices transmitting at a certain frequency. I want to use it to detect RF radiation in the 2.4 and 5 GHz range. I have a 1SS86 diode which works at high frequencies, a MMBR941 HF transistor (works up to 8Ghz) and a 2SC3356 transistor.
I also have a DC ampere meter (range 0-100uA) which I would want to use to measure the signal strength. Or I could use an LED instead. Or better I could use headphones to measure the radiation intensity as sound.
Basically I want to extend the range of this device (I think it's called lectenna.)
I tried to build it myself like it was shown in the video and the LED and ampere meter only detects the radiation when the 1SS86 diode is near the Wifi antenna (the meter shows a 10uA at a distance of 10 cm from the antenna and spikes up to 100uA when I move it right near the antenna). But if I move further away from the router, like more than 15 cm away, the meter does not record anything. So I thought that I need to somehow amplify the signal so thought to use a transistor but that did not work for me so maybe some of you could help me?
For the 2.4GHz I use a dipole antenna with a total length of about 5.9cm (2.95 cm in each side), like it is shown in the video. I do not have a variable capacitor to create a LC circuit so I am using fixed length of the antenna in a hope that this can bypass the use of variable capacitor.
If I absolutely need to create a LC circuit, I can build the coil myself and for the variable capacitor, I could try to make one using aluminium foil and paper like in some Youtube videos although I am not sure that it will work at such high frequencies.


texts: Voltage Bridging (Impedance bridging) Question in Cascade Amplifier

texts:
I understand that impedance bridging in audio applications is simply a voltage divider so by making output impedance of first device as low as possible and input of the second device as high as possible we get better results for transmission and power loss.

How can i calculate an amplifiers impedance so i can create second amplifier accordingly and connect them cascaded. I provided an amplifier design of Texas Ins. 1000Hz low pass with 1500Hz stopband. Are these resistors R1_Sx, R2_Sx at input of opamps selected according to this impedance bridging concept. If so, how do we calculate the impedance at input and output of each cascade block?

Secondly could you provide me some sources on this topic that i can learn for audio applications.


texts: How do you choose between 450 V vs. 750 V as a power source for your EV?

texts:
I am wondering what the decision factors are to help choose between 450 V DC and 750 V DC power source for an EV (electric vehicle).

The propulsion system is available in voltages between 350v and 750v. Other than the obvious price of parts, weight, parts availability and torque available, i was wondering if there was a factor i was maybe overlooking. Are there white papers on the subject?

Yes i did look on google first and found nothing that interesting on the subject.


texts: I am developing an embedded system that performs GPS and Wifi operation with separate modules for each and two SMA connectors to connect the respective antennas. Once it is being installed, is there a way I can identify whether the antennas are connected properly or the cable I am using is broken? As I am writing the diagnostic software, it would be great if I could include this case so as to identify wrong installations.


texts: AVRISP MKII does not appear in AVRStudio 4 (latest build 4.18 SP1)

texts:
I have a AVRISP MKII that I wish to program avr chips with through avrstudio 4 with.  However on the "select platform" the only think that resembles MKII is JTAGICE MKII which is not what I have?  Am I missing something here?  When I plug in the AVRISP MKII the drivers are all working and says it "sees" the device at least in windows.

Thanks,

Ril3y


texts: True Random Number Generator by using avalanche breakdown

texts:
I am trying to  build a TRNG using avalanche breakdown for randomness. I am developing a circuit as looks like this.(https://web.jfet.org/images/rng-circuit.gif)

Before I complete the circuit i wanted to be sure that my transistors generate random voltages. So I tested the avalanche breakdown voltage with a digital multimeter.

I checked the voltage from the red points in picture. But when I tested it, there was only a constant voltage of 8V. I thought it should be randomly changing between 8-0 volts. Is this normal ?


texts: I don't quite understand this FET-BJT preamp circuit

texts:
I see this circuit a lot on electret microphone preamps, but I don't quite understand it.  The FET is operated as a common source amplifier, so it has gain, inverts, and has relatively high output impedance.  So it would make sense to follow it by a buffer.

The BJT is common collector/emitter follower, so it would seem to be acting as just such a buffer, right?  It would be non-inverting, with near unity voltage gain, and low output impedance to drive other things without being degraded.  The voltage signal from the FET is passed through the capacitor to the base of the BJT, where it's then buffered and shows up at the output of the BJT.

What I don't get is why the FET's drain resistor is connected to the output of the BJT, rather than to the power supply.  Is this some kind of feedback?  Wouldn't it be positive feedback?  (As the FET's output voltage increases, it pushes the base voltage upwards through the cap, which then pushes the output voltage upwards from the BJT, which then pulls the FET voltage upwards, and so on.)

What advantage does it have over a circuit like this?


texts:
I recently started playing around with micro-controllers, and with a pc interface and it's software, when reading a program from a micro controller i got a field that said OSCALL byte and seems to give me a different value everytime, my question is, what is this byte? What does it stand for?

From the name i would guess something like OSScillator CALLibration, although both the S and L are doubled, this is what makes more sense to me...

Best Regards


texts: Does the Maxim DS18S20 stop converting temperature if a reset is sent during the conversion?

texts: I have a couple of devices on a 1-Wire network including a DS18S20.  If I start a temperature conversion, it takes 750ms for it to complete.  During that time,  I would like to query other devices on the network and then come back to read the scratchpad to get the temperature.  Querying those other devices will send a number of resets down the line and I am wondering if they will stop the in progress temperature conversion?


texts:
Edit:

I successfully made it work, but the algorithm not efficient
I taking the date coming in to my block, pipeline the data for how much points I need to median filter (for example 31), take all the 31 pipeline points and send to sorting algorithm block which returns bus with the sorted data, from this bus I taking only the median value (middle of the bus) and output it.

The only hard thing in this block diagram I sketched is the sorting algorithm, right?
So I found verilog code in GitHub for bitonic sort:
https://github.com/mcjtag/bitonic_sorter

connected it to the rest of my block, and everything cool I getting the sorting right and successfully calculating the median value every clock cycle.
This approach working but because this much of comparators every clock cycle I'm overloading my FPGA with complexity and a lot of LUTs (I sorting 31 points every clock cycle.. that ALOT).

How you guys think I should make this median filter algorithm better? sorting the whole array every clock cycle seems like solution but naive one.


texts:
I am studying the RTS 96 test system for a power system simulation in Matlab. I have noticed that under the Branch Data file, there are some buses which have two lines connecting them. For example (from Table-12.txt) between buses 115 and 121

ID#       =  Branch identifier.
             Inter area branches are indicated by double letter ID.
             Circuits on a common tower have hyphenated ID#.
Lam-p     =  Permanent Outage Rate (outages/year).
Dur       =  Permanent Outage Duration (Hours).
Lam-t     =  Transient Outage Rate (outages/year).
Con       =  Continuous rating.
LTE       =  Long-time emergency rating (24 hour).
STE       =  Short-time emergency rating (15 minute).
Tr        =  Transformer off-nominal ratio.
             Transformer branches are indicated by Tr <> 0.

 ID  From  To  L -  Perm.     Tran.   R     X     B   Con LTE STE Tr
 #    Bus Bus miles Lam-p Dur Lam-t   pu    pu    pu  MVA MVA MVA pu
A25-1 115 121  34   .41    11  0.8  0.006 0.049 0.103 500 600 625 0
A25-2 115 121  34   .41    11  0.8  0.006 0.049 0.103 500 600 625 0

Is the reason purely physical, meaning, introducing redundancy to increase system security? When it comes to modeling, can I just combine these into one transmission line (with appropriately modified parameters)?


texts: How to improve this amplifier so I can get up to 5 Watt output in 8ohm load

texts:
This is Class A amplifier I trying to make up to 5 Watt output for 8 \$ \Omega \$ load.
  Is this amplifier circuit OK?t gives about 800 mW out on 8 \$ \Omega \$ load.


texts:
I'm going to make a PIC programmer, so currently I'm acquiring parts that I'll need. And here's the one part that I can't get:

C2 - 22uF / 16V tantalum or 47uf / 6.3V tantalum
This is a high speed capacitor and should be a tantalum type.

That's what it says in the tutorial.

So my question is: Can I replace this tantalum capacitor with \$22\mu F\$ / higher voltage or \$47\mu F/ 10V\$ or something like this? I'm confused because in tutorial they are using \$47\mu F/6.3V\$ as replacement ...

How do I know how many farads I need ?

Thanks


texts:
What is the difference between SMD and pad in Eagle?

Can I use both to solder?

I am trying to make a PCB for my LEDs and I don't know I have to use SMD or pad.


texts: Why would btfss fail sometimes on PIC12f1822

texts:
I have a PIC12f1822 in a simple circuit, running very simple code. In a critical loop in the code, a BTFSS instruction mis-reads the port pin. This happens about 1% of the time.

To a first approximation, the code is simply copying the state of pin 4 to either pin 2 or 3, depending on the state of pin 5. The PIC is supplied with regulated 5v. Strangely, this problem only seems to manifest if I use 0v-5v input signals. If I use 0v-3.3v inputs, the problem seems to go away.

Is there any strange electrical property of a PIC which can make it miss read a port pin 1% of the time?

MAIN_LOOP

    btfsc   CS_INPUT
    goto    MAIN_LOOP

    movlw   B'00010000'
    btfsc   INDF0, 2            ; INDF0 points to PORTA
    movlw   B'00100000'
    movwf   INDF1               ; INDF1 points to LATA

    movlw   B'00110000'

WAIT_CS_HIGH
    btfss   CS_INPUT            ; This test fails sometimes
    goto    WAIT_CS_HIGH

    movwf   INDF1

    GOTO MAIN_LOOP

    END


texts: What resistor should I use after changing this LED from using 220v to using 5v arduino?

texts:
I bought these LED things without realizing they require 220v (I assume that's for European mains wiring, right?). Anyway, I took them apart, and inside is a disk type LED, with a resistor, and a capacitor. The resistors were all 1000 ohm resistors, but the capacitors all had slightly different writing on them. 400v 470k, CARLI MTF 104K 450V 4E30 A02, CARLI MEH 104K 400V 5B27 A02.

I took the capacitor and resistor off of one of them, and it runs fine on 5v, I tried it with no resistor, 10ohms, 100ohms, 220ohms, and 330ohms. All worked fine, obviously each was a little less bright, but my concern is ruining the LED if I don't use the correct resistor/capacitor with the new voltage.

I'm quite new to this kind of thing. Usually I use regular 5mm LEDs, and I put either a 220ohm or a 330ohm resistor with them (no capacitor).

My question is, what resistor should I use with these LEDs to make them as bright as possible, but still safe from destroying them? Do I need a capacitor?

Thanks


texts: What manual switch do I need for multi power source system?

texts:
I have a 20A DC device that I am powering from two different 12V DC sources and one AC 120V source (the AC source will drive a PS in the case to supply 12V DC) depending on availability:

Internal Battery DC
External Battery DC
AC 120

So 3 power sources in, but the same feed line out to the device. I want a simple switch which doesn't need to maintain power between switchover—so completely disconnected from each source. I looked at a regular rotary switch but most don't handle 20A. Usually around an amp or two at most. Can you point me to a rotary that will work for this? I need 4 positions and 4 poles? (one position being "Off").


texts: AVR-C turning led off after number of blinks with interrupts

texts:
so what I am trying to do is that I am trying to make the led blink for a certain number of times before it turns off. I want to avoid using delays so I tried
utilizing the interrupt and I also used a placeholder value like x to count the number of times it goes through interrupt, so one it reaches that value it will turn off, however I am having trouble getting it to work, any ideas

            /*
             * GccApplication3.c
             *
             * Created: 2015-04-01 6:13:58 AM
             *  Author: Bangladesh
             */

            #include <avr/io.h>
            #include <util/delay.h>
            #include <avr/interrupt.h>
            #define stp_led PB0
            #define dir_led PB1
            #define led_port PORTB
            #define led_ddr DDRB
            #define F_CPU 16000000UL
            int x = 0;

            int main(void)
            {
                ///////////////////////////////////////////////////////
                led_ddr |= (1 << stp_led); //enable led as an output pin
                led_ddr |= (1 << dir_led);
                //led_port |= (1<<stp_led);
                led_port |= (1<<dir_led);
                ///////////////////////////////////////////////////////
                TCCR1B |= (1 << WGM12);  // configuring timer 1 for ctc mode
                OCR1A = 15625;
                TIMSK1 |= (1 << OCIE1A); // enable ctc interrupt

                TCCR1B |= ((1 << CS12) | (1<< CS10)); //Start at 1024 prescaler

                sei(); //Enable global interrupts

                 //Sets ctc compare value to 1hz at 1mhz AVR clock, with prescaler of 64

             while(1)
                {

                }
            } //end of while loop

            ISR(TIMER1_COMPA_vect)
            {

                function_details (10, 1);

            }

            void function_details (stp,dir){

                if (dir == 1){
                    led_port |= (1 << dir_led);
                }
                else if (dir == 0){
                    led_port &= ~ (1 << dir_led);
                }
            while (1){
                led_port ^= (1 << stp_led);
                if (x == stp){
                    led_port &= ~ (1 << stp_led);
                    return 0;
                    }
                    x++;
                }

            }


texts: 1 switch-bank, 1 rotary, 5 inputs, 3 devices, no idea how

texts: I have 3 separate LCD's which have 5 push buttons to control the LCD settings and power.  All push buttons on the LCD share a common ground.  What I would like to do is use 1 switch bank and a 3-position rotary switch to select which LCD to adjust the settings on, however I'm unable to find an elegant solution via google. due to space limitations, I am unwilling to use a giant multi-pole rotary.  Is there an IC that will handle this?


texts: Are there any "Translation Accelerometer"?

texts:
I find many "Rotation Accelerometer" such as "GY-85", "GY-521", but no one for Translation.
Are there any "Translation Accelerometer", can detect the XYZ axis movement?


texts: Finding saturation field of ferrite core from manufacturer specs

texts:
I want to wind my own ferrite core inductors for some power conversion. However, I am having trouble finding out when the cores will saturate from manufacturer's data. For example, this material datasheet gives me "Flux density (near
saturation)", which is about 300mT (what I expected). Let's call that \$B_{SAT }\$ or something.

Now, sometimes I can't find this spec, but there are a few that are suspiciously close. For example, this page tells me the 61 material has "Flux Density @ Field Strength" of about 250mT when H=15Oe (about 1200A/m) is applied. It seems this is a suggested \$B_{MAX}\$? I don't know. Here's another table with several values for "Flux Density @ Field Strength", and although the maximum flux density seems about right, the field strength values are all suspiciously round.

So, my question is: in cases like this, in which no explicit "field near saturation" parameter is given, what maximum value of the magnetic field should I use in order to calculate the maximum current in the inductor? Do I just rule of thumb 200mT, or is there some way of inferring something from other specs?


texts: How is byte addressable memory implemented? If the max word size is 8 bytes (64 bits), does the memory always read 8 bytes and then use logic to select the bytes you actually need (1, 2, 4, 8 bytes)? Also, how are the writes implemented?


texts: When using MOSTEFS as a switch I always see the drain connected to the higher potential and and the load and the Source is always connected to ground. Can you switch those so that the Source pin connects to the higher potential and the drain is connected to ground?


texts: "Equivalent resistance" of diode as \$V/I\$ used to evaluate an approximation

texts:
Consider the circuit in picture, used to measure the voltage across diode and current flowing through it.

simulate this circuit – Schematic created using CircuitLab

With this circuit I do measure the exact voltage across diode (\$V\$) with voltmeter, nevertheless the current measured with ammeter (\$I\$) is not the current passing through the diode, since \$I=I_d+I_v\$.

To evaluate the error committed doing the approximation \$I=I_d\$, is it correct to see if $$V/I << R_v$$
?

Infact, supposing in first place that the approximation \$I=I_d\$ is correct, and also interpreting the ratio \$V/I_d=V/I\$  as the "equivalent resistance" of diode, then, using the current divider, if \$R_d <<R_v\$, then the approximation  is justified a posteriori.

In other words is it correct to interpret \$V/I_d\$ as the resistance of diode, and consider the diode equivalent to a resistor for this porpouse (i.e. to evaluate this approximation)?


texts: Why resistor values are non-linear? What makes sense in 470 ohm?

texts:
I never figured that out. Why do we have 220 ohm and 470 ohm, rather than 100 ohm, 200 ohm, 300 ohm?

Any particular reason? maybe it's just legacy from old manufacturing process.


texts:
We have a system that uses OTP (one-time programmable) EPROMs, specifically the AT27C256. We would like to replace this EPROM with an EEPROM or Flash chip such that we can make our units field upgradeable, more serviceable, etc. Obviously, we want this change to require little to no hardware modifications. These EPROMS are currently the code storage for an 68HCP11 micro.

It looks like the AT29C256 would be a viable option, as we could use it with only one pin change (change Vpp to WE_N). However, it appears that these chips are not made any more and sourcing is very unreliable, especially as we need ~70K of them. As such, we're looking at any other reasonable options.

We've considered adding a daughter board that sits on our EPROM's footprint (PLCC32) and contains another flash chip (AT28 series?) along with whatever conversions are necessary to make it work with our HC11 micro. We've also considered adding an FPGA to the daughter board between the micro and flash such that a series of "magic" reads can perform writes to the chip, but this seems to be getting a bit excessive for a problem many others must have solved. It would, however, allow us to not use jumper wires on our existing boards.

What have others done in this situation?


texts:
I am trying to understand the boost PFC and how its controller works.

The output voltage always contains a voltage ripple depending on the capacitor value, but shouldn't the voltage loop reduce this ripple overtime and after some time there will be no ripple? I know it's due to the charging and discharging of the capacitor but, from a systems theory point of view, why is there always an error?


texts: Where does character pointer resides in memory, ROM or RAM?

texts:
I am running Embedded C on some ARM Cortex-M4 target which facilitates with both ROM and RAM support. I have a character pointer in my code:

char *temp = "";

Later in code I am modifying the variable as:

itoa(some_integer, temp, 10);

When I compile the code, compiler puts *temp in ROM section which cause exception to raise when trying to perform itoa(,,) operation as constant variable can not be modified. My question is that why compiler is putting char *temp into ROM section?


texts: How to build very low cost current transformer?

texts:
Im building low cost home energy monitoring system. I want to see how much energy is used by water heater, big water pump, kitchen equipment, lightning, computer. I would be awesome if I could measure every light and socket in my house.

I found relatively cheap current transformers at local market, but they are a bit too expensive for project like this (I need too many of them).

I need few current ranges (5A, 10A, 20A). I want to measure these currents with microcontroller ADC.

So, the question is:

How can I build low cost and relatively small size current transformer?

Does it have to be toroidal, to be small (under 2x2x2cm for 20A CT) and cheap?
If it has to be toroidal - what kind of core can I use? Iron powder cores are very cheap - can I use it? I can buy iron powder cores (AL range from 33 to 83). for 0.10EUR.

I know that winding toroids is complicated, but I have some mechanical skills and I feel I can build little toroid winding machine if toroid is required for small size.

If someone reply with exhaustive answer (in form of howto?) I will award it with big bounty (after 2 days).


texts: Why is output voltage being neglected when calculating power supplied by this current source?

texts:
If you look at the fourth equation, the example is attempting to calculate the power supplied by the current-controlled current source on the far right of the circuit. For the equation P = I * V, they are plugging in 8 volts for V, which is the voltage across this current source resulting from the voltage source on the other side of the circuit.

What bothers me is that the current source should be outputting a voltage as well. Why is this not being factored in? Shouldn't the voltage value plugged into the power equation for that current source be equal to the 8 volts across it minus the voltage that it is outputting as a source?


texts:
Please open schematics of Mega.

Can anyone explain why Cap C1 is used here? C1 is connected to RESET pin of ATmega2560. Also, ATmega16U2 pin 13 is connected to the RESET pin of ATmega2560. I am just not able to figure out the significance of this Capacitor in Auto RESET circuit.


texts:
I have accidentally shorted my circuit (5 Volt Vcc) for approximately 1-2 seconds max.
While the circuit was short circuit I use the FLUKE as ampermeter in miliAmper mode (400mA max fused)
The current was reach above 400mA (I think 480mA and then I quickly disconnect it ) and now I am afraid that the fuse was damaged.
I can still see current measurements and I did fuse test and the resistance I got is 8kOhm. It is sound too big for me but FLUKE manual says that the result should be lower than 10Kohm.

link to FLUKE user manual

As far as I understand the Ampermeter should have very low resistance (close to zero) so do you think 8Kohm it is still good? and why FLUKE says below 10Kohm it is good?

Thanks


texts: Art of Electronics Ex.2.20 Series negative feedback amplifier

texts:
Here is the exercise followed by a schematic:

  Applying the techniques we used earlier, one can show that G(open
  loop) ≈ 200, loop gain ≈ 20, Zout(open loop) ≈10k, Zout(closed loop) ≈
  500Ω, and G(closed loop) ≈9.5. Exercise 2.22. Go for it!

Here is my analysis:

First lets calculate open loop gain cutting the feedback (bottom leg of R5 and grounding it). The amplitude of the gain of the first stage (common emitter amplifier formed by Q1) is

R3/R4 = 0.62

( I am ignoring re1=25 Ohm here, since R4>>re1).

For the second stage the OL Gain is

R5/re2 = 10kOhm/25ohm = 400.

So the total open-loop gain is: A = 400*0.62 = 250.

Feedback network is formed by R5,R4 voltage divider and returns signal voltage to the input with the ratio of B = 1/10.
So the

loop-gain = A*B = 25.

Now total closed loop gain (from previous chapters of the book) is:

A/(1+AB)=250/26 = 9.6.

This is the first problem. Why am I getting 250 for the open loop gain, insted of 200 as it is given in the book?
With the A = 200 all the following values are also exactly correct. Is there a mistake in my reasoning?

Then we calculate Zout (open loop) performing same feedback removal as before. Then our output impedance is simply

R5||(closed collector-base pn junction resistance).

Considering that the later should be in the range of MOhms I can neglect it and Zout (open loop) becomes

Zout(open loop) ≈ R5 = 10kOhm.

Now for Zout(closed loop). Looking into the output:

Zout(closed loop) = R5 + R4||[re+ (R1||R2||Rs)/ß] ≈ R5+50 Ohms ≈ R5,

where Rs is the source impedance (not shown) and not considered (Rs=infinity), and ß is the intrinsic transistor current gain, which I consider to be ß = 100, as was done earlier in the book.
This is the second problem, since in the solution it should come out to be 500.
This is what one gets if we simply say: "since it is a negative feedback, then"  :

Zout(closed loop) =Zout(open loop)/(1+AB)  ≈ 500 Ohms if we use A = 200

                                               ≈ 400 Ohms if we use A = 250.

But why brute force analysis did not work at all (as it was done for the previous similar example in the book)?


texts: Can we use a power amplifier (Class AB) in the inverter portion of a VFD?

texts:
I would like to float this idea of using a good (audio) power amplifier in the inverter stage of a sub 1KW VFD. How does this idea sound ?

On the plus side, there is far less switching noise, since we can synthesize the pure sine from an MCU and feed that to the power amplifier directly.

On the minus side, power dissipation would be much more than using a class D design?

All expert/intermediate/novice views are welcome. use a good audio power amplifier in the inverter portion of a sub 1KW VFD?


texts: The definitive method to probe the device operating current

texts:
How can I measure the current a device consumes?
I tried one that has 1.5 V power supply requirement.  I measured its resistance with a DMM from the power supply box (with the batteries removed) by connecting the two poles.  It read 1.41 Mohm, so I thought the answer is more than 1 microampere.
When I put the DMM in series with the power supply (with batteries installed) reads  2.45 mA i.e. gives device resistancr about 0.6 kohm (1.5V / 2.45 mA.)
What is the correct method to measure the current?


texts: Is the communication between the USB or PS/2 keyboard and the computer simplex, duplex or half-duplex (unidirectional or bidirectional)?

texts:
I am curious to know if the communication between the computer and keyboards is unidirectional or bidirectinal.

Until a few days ago i thought the communication is unidirectional because only the keyboard sends data to the computer and the computer interprets this data.

Also the article from which I learned about simplex,duplex and half-duplex gave as simplex communication example the communication between the keyboard and the computer.
http://www.iec-usa.com/Browse05/DTHFDUP.html

However I discovered that using virtual keyboard programs such as On-Screen keyboard you can actually tun on the caps lock, num lock or the scroll lock and the LED indicator turns on or OFF accordingly on the keyboard. This has to mean that the computer also sends data to the keyboard. Is this correct?


texts: Sizing Resistors for Voltage Divider Circuit Feeding Solid-State Relay

texts:
I need some assistance in sizing the two resistors for a voltage divider circuit in order to drop from 48V DC to somewhere in the 4V-32V control voltage range of the Crydom DC100D40C solid-state relay.

The chart below (pulled from the datasheet linked above) shows the relationship between input voltage and input current for this relay:

At the minimum control voltage of 4V, the current is approximately 8 mA.  At the maximum control voltage of 32V, the current is approximately 13 mA.

There is a bit of a disagreement/discrepancy between the "Minimum Turn-On Voltage" of 4V and the "Minimum Input Current (for on-state)" of 11 mA (at least in terms of trying to locate that point on the chart above), but in the interest of modeling the full range of input values in a linear way, let's take the 5V/10mA point as the bottom end.

So at the low end (5V/10mA) the control side of the relay "looks like" a 500Ω resistor.  And at the high end 32V/13mA point, it "looks like" a 2.462kΩ resistor.  (I know this is a grave oversimplification/inaccuracy, but hear me out and then chime in at the end :))

Ignoring for a moment the relay current/voltage/"resistance", and just trying to target a voltage divider output voltage smack in the middle of the relay's input range (18V), I can [almost completely arbitrarily] select values R1=20kΩ and R2=12kΩ in order to get an 18V output (http://www.ohmslawcalculator.com/voltage-divider-calculator).

But if I then (in CircuitLab) model the relay as a resistor (at the mid-range 18V/12mA/1.5kΩ data point), the actual output voltage of my voltage divider drops down to 3V instead of 18V.  If I use the low-end "effective" resistance value of 500Ω (with the same two original R1/R2 values) it's only 1.125V (instead of 18V).  At the top-end value of 2.462kΩ, the input voltage to the relay is at least within-spec (but just barely) at 4.449V.

Reducing the sizes of R1 and R2 (while still maintaining the same ratio) increases the voltage (i.e. upwards from 4.449V), but since everything is all interconnected/interrelated I know it is invalid for me to just alter one set of parameters without re-evaluating the others.

The other factor is that ideally R1 and R2 would be as large as possible in order to minimize current flow and drain on the battery.  But the relay still needs its 11-14 mA in order to trigger, so the resistance can't be too high.

As I admitted above, modeling the relay as a resistor is wrong; I know that. But I am struggling to figure out how to model/calculate/confirm this setup with various values of R1/R2.  I want to have R1/R2 large enough that drain on the battery is minimized, but I'm not sure how to calculate what the top-end limit should be in terms of them being too large.

Any assistance/recommendations you could give on sizing resistors in order to achieve the desired voltage drop and satisfy the input requirements of this relay would be much appreciated!  Thanks!


texts: Why does the TUF formula use \$V_{rms}=\frac{V_m}{\sqrt{2}}\$ and not \$V_{rms}=\frac{V_m}{2}\$ for a half wave rectifier

texts:
We know that for a half wave rectifier \$V_{rms}=\frac{V_m}{2}\$ and \$I_{rms}=\frac{I_m}{2}\$

But the Transformer utilization factor uses \$V_{rms}=\frac{V_m}{\sqrt{2}}\$ (But uses \$I_{rms}=\frac{I_m}{2}\$) to calculate the "ac rated power" as \$\frac{V_m}{\sqrt{2}}*\frac{I_m}{2}\$. Why?


texts:
I am a beginner in Microcontroller electronics.

MPC5606S MCU Datasheet

I want to understand how to read the table 8 - Port Pin Summary. Can you please explain clearly the each word present in the function and peripherals column? Ex. eMIOSA, SOUND, SIUL, DCU etc. What is the purpose? Please.

And Some ports have 5V input and some ports have 3.3V input. Where to find this information in the attached datasheet? I think table 5 gives the Voltage for the input ports. For output ports, how do we understand which pin/port gives which voltage i.e. 5V or 3.3V?

Thanks.


texts:
Here is a sentence from Design of Analog CMOS Integrated Circuit that I don't quite understand:

"Note that in contrast to bipolar transistors, a MOS device may be even on if it carries no current."
Could you explain this?
Ron = Vds/Id
If there is no current then Ron is infinity.
How is it possible for the device to be on?


texts: Are passive piezo speaker more reliable than magnetic ones?

texts: I'm going to use sound notification in my desing (just beeping). My buzzer needs to be suited for cold ambient conditions (up to 0 celcius degrees), high humidity and shocks. Which buzzer type will be more aproperiate? Is it true that piezo buzzers are more reliable?


texts: What analogue input voltages does this ADC understand?

texts:
I have a 14-bit ADC for which I do not know what the "accepted input voltage" is.

The datasheet specifies that there are "out-of-range" signals, but I cannot find what the range is. What is the range of my ADC?


texts: Does the Arduino Uno “Clean” the power input from the adapter?

texts:
I am building a temporary Arduino project, and I need to order an adapter online. I am concerned that, if my adapter has lots of noise, it will affect the Arduino. Since this is temporary, I am going to buy a dirt cheap adapter to save money, but will it be "smooth"? I don't care if it breaks; two of them are much cheaper than the cheapest one that I can find on Sparkfun or a similar website.

If I hook up a fairly 'dirty' adapter, through the VIN pin or the power jack, will it filter out the noise? Will it still filter this noise out if I have a 'dirty' 5V adapter connected through the 5V pin?


texts:
I don't understand why in the circuit $$V_{saadc} = V_{ain}\cdot{(C_{ext} - C_{sample}) \over C_{ext}}.$$ Can anyone please help me to understand this equation?
This circuit is for measuring a lithium battery with the SAADC of the NRF52 chip. In the next link there is more information about the circuit.
https://devzone.nordicsemi.com/blogs/943/measuring-lithium-battery-voltage-with-nrf52/


texts: How to wire MCU control signals with power and ground to control multiple external motors?

texts:
I'm working on a system based on a NodeMCU/ESP8266 WiFi controller, which controls two separate motor units, each consisting of a 12V motor and solenoid actuator. For practical reasons, I need to physically separate the controller box from the motor/actuator boxes by around 6 feet.
Here's a diagram with a single motor unit, capacitors and diodes omitted for clarity. In reality, there will be 2 motor units in parallel with independent control signals:

What's the standard way to wire this to reduce signal degradation due to EMI?

Combine all conductors (control/GND/12V/3V3) in the same cable. Requires twice as much cable and thicker gauge for all conductors because of high current requirements on 12V/GND, significantly increasing cable cost.

Separate GND/12V/3V3 conductors from control signals. Control is routed without ground, i.e. no shielding, therefore susceptible to EMI. We cannot also include ground with control, since that would form ground loops.

Include ground with the control signals, wire 12V/3V3 separately without ground. It feels wrong to wire the positive rails without ground, but not sure why.

Please let me know if there are any other issues with the circuit, e.g. sharing ground between MCU and inductive loads.
Thanks for your help!


texts: Logic Level Conventer for UART 5V / 3.3V with high transmission speed (115200)

texts:
I need to connect ESP32 (3.3 V) and Arduino UNO (5 V) on the UART bus. I used to connect two devices through a 1k resistor and it worked. I want to make a reliable connection.

On the Internet, I found a matching circuit for UART levels based on a BSS138 transistor.

Will this scheme work reliably at a transfer rate of 115200 BOD? If it were not, would you advise me a more reliable option?


texts:
Not really having any application in mind, I am playing with batteries and MOSFET. Here I want to turn on 2 batteries using a third battery. Here is the problem, when gate is HIGH, Va = 6.1v; Not the 8v that it should be since 4+4=8; Vb = 2.1v and Vds= 1.8v; Seems to me, Vgs is not high enough. Increasing Vgs sloved the problem, but clearly we are using 3 same kind of lithium batteries here, and changing the voltage is not an option. Now, when Vgs = 0, or LOW, strangely, Va= 2.2v now and Vb = -1.7v. This is very strange, indeed. I have no clue where the 2.2v and -1.7v came from.

Here is my improved version. When V3=4v or HIGH, Va=8v and Vb=4v; that is good. That is what I have expected, but when V3=0 or LOW, Va=2.27v and Vb=-1.7v; almost same result as the above circuit, so what is cause for this strange output and what is correct and properly way to use MOSFET to switch batteries in situation like that?


texts: How a person standing on a floor tile and holding a live equipment can complete the circuit?

texts:
Can someone please explain the how grounding / earthing to prevent a person from getting electrical shock using simple illustration of a faulty electric iron connected to the 240VAC mains?

I don't understand how a person standing on the floor tile in the house and holding a live equipment can complete the circuit for current flow. Where is the connection from the ground to the back to the equipment?


texts: Type of Header for Motherboard PWR Switch

texts:
I am trying to make my own 2-position connector cable to connect a Rasberry to the PWR_SW's PWR and GND pins on the motherboard system panel headers, as shown in the diagram below.

Can you identify the type of connector? Also attached a photo of how it looks like.

If it's simply known as a connector, how should I filter down to this type of connector on Digikey?


texts: AS5048A SPI - 13bits instead of 14bits resolution

texts:
I'm trying to make a driver for as5048a (spi) on STM32f405rg
This magnetic encoder is supposed to have 14bits of resolution :

and the read package shows that the 2 MSB are parity and error flags

So I'm masking them :

uint8_t rMSB=0, rLSB=0;
AS5048A_cs(&self->cs, 0u);
rMSB = SPI_read_byte(self->spi);
rLSB = SPI_read_byte(self->spi);
AS5048A_cs(&self->cs, 1u);
*buf = (((rMSB << 8) | rLSB) & ~0xC000);

But when reading buf, I only get values from 8192 (0x2000) to 16384 (0x4000).
Maybe someone has already face this problem and could explain what I'm doing wrong.
EDIT :

As said, the as50148a needs two transmissions here's what i do :

{

uint16_t command = 0b0100000000000000; // PAR=0 R/W=R
command |= reg;
command |=((uint16_t)spiCalcEvenParity(command)<<15);
// send register address to be read
uint8_t MSB = (command>>8) | 0xFF; // shift the upper 8 bits down
uint8_t LSB = command | 0xFF; // mask upper 8 bits

AS5048A_cs(&self->cs, 0u);
SPI_write_byte(self->spi, MSB);
SPI_write_byte(self->spi, LSB);
AS5048A_cs(&self->cs, 1u);
/*
second command should be 0x0000 (nop) or clear flag (0x0001)
but when sending the second command, there's no angle returned.
thus by commenting this it gives me an angle from 0x2000 to 0x3FFF
AS5048A_cs(&self->cs, 0u);
SPI_write_byte(self->spi, 0x00);
SPI_write_byte(self->spi, 0x01);
AS5048A_cs(&self->cs, 1u);
*/

uint8_t rMSB=0,rLSB=0;
// read data
AS5048A_cs(&self->cs, 0u);
rMSB = SPI_read_byte(self->spi);
rLSB = SPI_read_byte(self->spi);
AS5048A_cs(&self->cs, 1u);

*buf = ((( ( rMSB & 0xFF ) << 8 ) | ( rLSB & 0xFF )) & ~0xC000);


texts: Open circuit resistance in common gate amplifier

texts:
I am reading about common gate amplifier on this page and there is a small signal model that I am a bit confused.

The common gate amplifier and its small signal model is shown below.

As you can see there is an open circuit resistance r_{oc} at the output of the small signal model.

Could anyone tell me where does this resistor come from?


texts:
I bought a GM862 module some while ago, I inserted the SIM card and made all the necessary configurations but I always get the:

AT+CREG?
+CREG: 0,2

response, which means that is trying to get a network but can't succesfully connect. Now the question is: Do I need to install an antenna in order for it to work? (I didn't buy one because I thought it has an internal antenna.)


texts: How does USB-C handle simultaneous data and video?

texts:
Some USB-C adapters offer a video output as well as a standard USB output.
Such an adapter (for example with a USB port and a HDMI port) can handle simultaneous outputs: i can have video coming from the HDMI port while transfering data to a USB disk with the same adapter.

I am assuming the video output is coming from an USB alternate mode (HDMI in our example), so this means both signals go through the same pin.
How does this work in practice?


texts: Can Solenoids Get Sticky From Improper Usage?

texts:
I bought three spring-return, push-type solenoid. I can't remember them being sticky from the start because I only was using one at a time, but they may have been. Now that I tried to work them together, two are so sticky that they have become unusable (even by themselves).

I would like to know whether this may have happened progressively because of pushing them a bit hard (I hardly used them though), or wrong components or because I hooked the three up at the same time.

Here is a bit of info on my setup:

Spring-return, push-type solenoid. 14 Ohm, 12-24Vdc coil. Intermittent duty
RECT DIODE 1AMP/400PIV
12VDC 3.33A SWITCHING POWER SUPPLY
N-CHANNEL MOSFET, 55V 22A .06OHM
Resistors
Arduino Duemillenove


texts: How to best synthesize a systolic circuit on FPGA?

texts:
I am developing a parameterized systolic circuit in VHDL, using generics. It exhibits regularity in 2 dimensions.

I am about to synthesize it on Xilinx FPGA. I suspect it is worth informing the logic synthesizer about this regularity, in order to achieve better performance in terms of final area.

How can I do this ?

I have already discover the "keep hierarchy" option in Xilinx ISE, but it is not clear if it will make the job.


texts:
I was reading an article about working of ESP at this website:
https://www.electrical4u.com/electrostatic-precipitator/

Though the explanation was nice, I couldn't understand what the diagram conveys.
Anyone who can help with the meaning of the diagram on this page?


texts: Lots of different darlington pairs datasheets indicates that NPN are faster(lower rise and fall times), stronger(has a higher Hfe and bigger current maximum) and because of gate source tension, easier to use than PNP(logical HIGH of 3V3 can drive a NPN directly, while PNP needs other transistor to pull down the gate voltage from Vcc). Why so many H bridges schematics has the high side filled with PNP? If they differ in so many specs, it would be bad, isn't? Why just don't use all the same type? And confirming this, why not the most eficient type?


texts: Lighted button that also lights when another button is pressed

texts:
I've got a project, started 12 lighted and latching buttons in a circle, like a clock. Press a button, the button lights until it is pressed again. I need a second "clock" and if say the 2 o'clock button is pressed on either clock. If this happens then button should light, as well as the corresponding button on the other clock. Pressing the 2 o'clock button on either "clock" would turn off the light.

Since states can change from a second location now in this scenario, the latching switches would need to go and be replaced with momentary lighted ones, and then the logic controlled with an arduino, raspberry pi?


texts: Verilog nested for loop not behaving as expected

texts:
I am having trouble with a simulation of an 8-bit full adder i wrote in verilog. Basically I have two integers that I feed into the full adder, I add them together and I check if the result is as expected. Here is the code:

full_adder_Nb_tb.v:

`timescale 1ns / 1ps
`include "config.v"

module full_adder_Nb_tb #(parameter  N = 8)();
reg [N-1:0] a;
reg [N-1:0] b;
wire [N-1:0] s;
wire co;
integer i, j;
integer error_cnt;

full_adder_Nb #(N) test_module (a, b, s, co);

initial
begin
    $display("TESTING full_adder_Nb.v");
    error_cnt = 0;
    for (i = 0; i < 2^(N-1); i=i+1) begin : outer_loop
        a = i;
        for (j = 0; j < 2^(N-1); j=j+1) begin : inner_loop
            b = j;
            #5;

            if (s != (i+j)%(2^(N-1)) || co != (i+j)/(2^(N-1)))
            begin
                error_cnt = error_cnt + 1;
                `ifdef VERBOSE
                    $display("There was an ERROR. Inputs: a=%d,b=%d, outputs: s=%d, co=%d. Expecected value: s=%d, co=%d", a, b, s, co, (i+j)%(2^(N-1)), (i+j)/(2^(N-1)));
                `endif
            end
        end : inner_loop
    end : outer_loop

    // SIMULATION FINAL OUTPUT
    if (error_cnt == 0)
    begin
        $display("full_adder_Nb.v WORKS correctly.");
    end
    else
    begin
        $display("full_adder_Nb.v does NOT WORK. It has %d errors!", error_cnt);
    end

    #20;
    $finish;

end
endmodule

This is the result of the simulation:

As you can see integer i and reg a are both stuck at 0, while j and b are behaving as inteded. I do realise that this does not fully test this circuit (I intend to add negative numbers simulation).

I am grateful for any hints.


texts:
In this answer they talk about SAW (Surface Acoustic Wave) and SDL (SAW Delay Line). I understand SAW can be used to create filters, oscillators and delay lines.
I would like to know what typical properties of SAW are, and following from that, what areas they are used in. For instance, they're used in HF, but do they also exist for LF like audio, or isn't that possible?
@JustJeff already mentioned that SAWs are narrow band.


texts: Impedance matching of an amplifier circuit with a filter at the input and output

texts:
I created an amplifier circuit with a filter on the output.

I did impedance matching on the input and then did matching on the output as well. From the graphs below, is the circuit more matched?
Picture of the amplifier itself with the filter:

Amplifier with filter with impedance matching at the input:

Amplifier with filter with impedance matching at input and output:


texts: Pulse width parameter in VI Characteristic curve of Diode

texts:
I was referring to the datasheet of IN4001 from Vishay
In Fig.4 (Typical Instantaneous Forward Characteristics), pulsewidth=300usec 1% duty cycle is given. I would like to know what this parameter is? In datasheet, there is no mention of pulse width it looks.


texts:
I am new to electronics, I want to connect 10 watt leds like below diagram. What power supply should I connect, and how to calculate the required power supply for any number of LED of any Watt.

LED Specifications:

List item

Item Type:LED Light (10 Watt)
Intensity: Typical 800~900 Lumen
Voltage: 9 to 12 Volt
Forward Current:1000mA
Beam Angle(°):120°
Average Life (hrs):Greater than 50000 HRS
Color:White Color
Temperature:Cool White(5500-7000K)


texts:
I am implementing a TRNG on an FPGA. This TRNG is based on jitter created by ring oscillator and I would like to know how to implement the given ring oscillator on FPGA so that jitter is generated.

module rng(start, r_out);
input start /* synthesis keep */;
reg rout /* synthesis keep */;
output r_out;
wire n0 /* synthesis keep */;
wire n1 /* synthesis keep */;
wire n2 /* synthesis keep */;
wire n3 /* synthesis keep */;
wire n4 /* synthesis keep */;
wire n5 /* synthesis keep */;
wire n6 /* synthesis keep */;
and a(n6,r0,start);
mynot x1(n6,n0);
mynot x2(n0,n1);
mynot x3(n1,n2);
mynot x4(n2,n3);
mynot x5(n3,n4);
mynot x6(n4,n5);
mynot x7(n5,r_out);
endmodule

module mynot(
    input x,
    output wire y
    );
    not(y,x);
endmodule

This is my code for ring oscillator.

module rng_tb;
reg start;
wire q;
rng uut(start,q);
initial
begin
start=0;
#50 start=1;
end
endmodule

This is the code for testbench.

The output now is don't care.


texts:
I'm looking at an electrolytic capacitor (and old blue, Philips one used in electronics classes) and am wondering why it is printed with 4µ7-M.

I tried Googling, figuring that it was a common enough occurrence, but found nothing.

Is that supposed to be a 47µF cap? Why is the µ in the middle of the number? What is the -M for?

Thanks.


texts: Can failure of an old electrolytic capacitor be precipitated by motion?

texts:
I have report of a circuit board failure.  The board was 20+ years old, and included at least one electrolytic capacitor.  That capacitor would then be beyond its expected useful life.  The board was still functioning, until the moment someone moved the panel the board was attached to.  At that point, the board immediately failed, and has not recovered.  Component-level failure analysis is not possible in this situation.

It occurs to me that the electrolyte in the capacitors is liquid, and thus subject to motion, perhaps moreso if the capacitor is partly dried out.  So if an electrolytic capacitor is old enough that it should be considered end-of-life, but is still functioning and energized, is it possible that moving the energized capacitor would precipitate its failure?


texts: I want to disable EEPROM in beaglebone black by unloading i2c-omap driver. Will it create problem in hardware or any other software support? What should I expect ?


texts: How does current flow through a mono (TS) guitar cable?

texts:
My basic understanding of electronics says there must be a complete circuit for electricity to flow, so does that mean there is both a + and - wire inside a mono guitar cable? Or does electricity flow back to the amp/interface/mixer through the ground (the shielding)?

Specifically I'm wondering about a piezo or perhaps some other setup involving a small battery in which I can trigger impulses to flow into my recording interface, and I'm wondering how I need to connect it to the cable. Same thing as a drum trigger, except that my application will be more customized and require me to wire it up myself.


texts: Multimeter giving wrong current readings

texts:
I just got my first multimeter (TekPower TP8268) and I've been try to test it out, but I have been getting some strange readings with the current measurement. I have an AC adaptor to DC 12v and 5A. Here are the results I got across various resistor readings.

10Mohm -> 164mA -> 12.3V
10Mohm -> 173mA -> 12.3V

Here's how I hooked it up:

DC pos --- RES --- Mult-In --- Mult-Out --- DC neg /ground

I can't seem to figure out how I could have gotten these readings. If my calculations are right with Ohm's Law, 12V / 10Mohm = 12 x 10-7A (or .12 uA). I made most of these readings on a breadboard, but I have a hard time thinking it would throw the readings off this much.

I did, temporarily, switch the fuses in the multimeter, so these readings are using the u/mA range, but the 20A fuse. I don't know if that could cause the problem, but that's a possibility.

So, does anyone have any idea what might be wrong? Are there any additional tests I could do to help me figure it out?


texts: Should ferrite beads be closer to the stepper motor or to the motor driver?

texts:
Stepper motor, cable with ferrite bead, and dual H-bridge driver:

I noticed that the cable that came with these motors had the bead closer to one end. Does it matter which way it's wired as far as noise returning to the supply or EMI from the unshielded cable?

The H-bridge has a separate power supply from the MCU that toggles the H-bridge, but there is no electrical isolation anywhere.


texts:
I do not understand the basic of a Gilbert cell.

I see that as its output we consider the output differential current Io. But I do not understand it. Is the load connected between the points 1 an 2? Or is there VCC? Moreover, if the load is connected between them, why is the current flowing on it equal to the difference of Io1 and Io2?


texts: Can Static Electricity change the voltage reference of a PCB?

texts:
Problem:
After running a test that creates static electricity, the values acquired by a hall-effect sensor are not correct anymore.

Context:
The device I am working on draws and rolls up fishing wire/rope. I monitor the number of rotation it needs to rolls the wire up with (30) magnets all around the spool and an hall-effect sensor on its side measuring the number of magnet according to the direction of the rotation.

My set-up includes three parts: a main PCB, a smaller PCB with the hall-effect sensor and a zif cable that connects both PCBs. These PCB were designed by a EE firm and produced by a reliable mass-production facility. The issue is observed over different main and sensor PCBs.

On the firmware side: the main PCB reads the sensor values using interrupts running on the iRAM, with the MCU running at 240MHz. According to the direction signal it adds or subtracts to a volatile int every-time it senses a magnet. Then at the beginning of my state machine (every 50 ms) I LOG the values on the terminal and saves them every 2 seconds in the File System.

The monitoring works perfectly when no wire is on the spool, whatever the speed of the rotation or the stress on the test set-up.

When introducing the fishing wire, a discrepancy of one third of a rotation appears after 20 rotations; in other words, instead of having the correct result of 20 rotations, it measures down to 19.66 or up to 20.33 rotations.

The Weird part:
1) After observing the discrepancy, if the wire is removed from the test set-up and the test done again the discrepancy can still be observed.

2) The discrepancy is still observed after changing the zif cable or the sensor PCB.

3) Plugging out the electronics does not make the discrepancy disappear

4) The only solution to fix the discrepancy is to flash the firmware again.

5) Without wire, the results of the test are always correct.

Hypothesis:
The only reason I can think of after a week of tests is that the wire can somehow change the voltage reference somewhere on the PCB that makes some signal incorrect.

Disclaimer: I have tried to sum-up a test that took 2 full weeks of my time, I might have forgotten some details. I will try to update this post with every new findings.

Question: Can the voltage reference on the PCB be changed by wire rolling up next to a sensor?


texts: Do global variables consume more power than local variables in embedded systems?

texts: Today my colleague from work said that access to global variables on microcontrollers consumes more power than access to local variables, unfortunately she did not explain that. At the beginning, values of global varaibles are copied to RAM and then we operate on values from RAM, so how does it work that they consume more power? Are local variables stored in CPU registers, not in RAM ? We are programming in C language using GCC.


texts: Confusing component pin spacing info in datasheet

texts:
this is part of datasheet from Vishay. I want to do a footprint based on this picture, but can't figure out the dimensions...

The space between the pins is described two times: is says 0.220 (5.6) and 0.180 (4.6) at the same time. I just don't get it. Thanks for help.


texts: IGBT trailing edge dimmer: the LED bulb only lights up around 40%, strange wave form before that, please advise what is causing that

texts:
I built a trailing edge dimmer with IGBT, and I am driving it using Raspberry Pi 3.
The circuit mostly works, but I noticed some strange behavior, that I can't put my finger on.
Please could you help me understand what is causing these, and how could I fix them?
Issue #1:
The first issue can be noticed when I start dimming the light gradually without turning the bulb on beforehand.
If I am turning the light ON for 1 second, and then I am gradually increasing dimming ratio from 0% to 100% in 20 seconds, then dimming works nicely, and the signal looks good
(Oscilloscope recording can be found here).

However if I do not turn the light ON at the beginning, just start dimming, then the bulb remains off in the first 8 seconds, and the signal looks distorted in this period. After 8 seconds the light finally turns ON, and the signal looks good again
(Oscilloscope recording can be found here).

Please could you help me understand why the signal is distorted, and why the bulb remains initially OFF?
Issue #2:
A few seconds after turning the IGBT OFF I noticed a signal on the bulb.
This signal slowly decreases, and eventually "almost" disappears after a minute or so.
Please could you let me know where this signal is coming from?
(Oscilloscope recording can be found here)

Circuit:

Please could you give me any pointer?
(My zero-cross detector fires early, that can be noticed on the pictures. I will fix that later in software. I believe this has nothing to do with the issues.)


texts: Difference between Proteus results and KCL-deduced formula

texts:
I'm designing a small circuit using an op-amp for a temperature sensor (PT100).
I took the design online (see below).

I tried to find out the formula for finding the value Vout as a function of the input voltage.
I've used the KCL (I think it's Kirshoff-current-law) at the various junction points.
I got a formula that gives values that are offsetted by 0.2Volts from the output produce by a simulation of the circuit in Proteus (original diagram in LTSpice as seen in the picture above).
My question is: is it common for proteus to add an offset during the simulation, or am I necessarily making an error in my computations.
Thanks in advance


texts:
I'd like to put a pump drive circuit similar to the one shown below on the same PCB that has two I2C devices, a GPS module, seven analog signals, an ESP32 MCU transmitting WiFi via a trace antenna, and a SPI bus with a microSD card and flash.

I'm worried about signal interference with all the switching going on (the pump is driven with PWM at the MOSFET). Is there a way to mitigate this by simply separating the circuits to different regions of the board, or using an RF shield? If it's the latter, where would I put the shield? Over the microcontroller? Over the pump drive switching components?

I don't mind putting it on a different PCB but if there's a way around it I'd prefer to have it all on one board.


texts:
In a data acquisition system voltage is sampled. For some reason we need the current values instead of voltage. One can do it by just dividing voltage to a resistance R. The point is the resistance is not precisely 250 ohm so we need to measure it more accurately. We have a constant current supply which is precise for 2 current levels 4mA and 20mA. We applied first constant 4mAmp and then 20mAmp to the resistance and measured the voltage with a voltmeter.
Then we calculated the resistance of that resistor for each measurement.
The point is at different currents the resistance is measured different.
Data acquisition will measure the current loop's voltage correspondences coming from the device spitting exactly between 4 to 20mAmps. My question is which resistance value is more precise since the resistance changing with the current. Do you think the best way is to take the average of 2 measurements at 4 and 20 mAamps? Another thing is how can we trust the voltmeter's readings. Is there such thing as digital voltmeter calibration? Does it make sense for our resistance measurement?


texts: How to split an 8 bit BCD number into two separate 4 bit BCD numbers using logic gates or VHDL?

texts:
I think this might actually be quite simple but I can't find info on it anywhere and I can't think how I would do it. I want to split an 8 bit BCD into two 4 bit BCDs so for example if I get an input of:
01011100 I want two separate outputs of 0101 and 1100.
Similarly how could I then split the 0101 into 4 outputs of 0, 1, 0, 1 and the same for the 1100 into 1, 1, 0, 0?


texts: Chaining output of amplifier (to speaker) to another amplifier

texts:
I purchased this holiday card sound recording module: Link.

It's hooked up to a 0.5W 8Ohm speaker, and the IC is shielded from the outside world, so I really only have access to the outputs to speaker positive and negative. The sound is pretty poor, and it crackles at higher volume (not sure if it's because of mic being poor as well).

I have one of these HeadRush Pop-up speakers. Sound is pretty good, not sure of specs of speaker but back of it says "A K 7I14" and it's for sure better than the recording module (which is made of a piece plastic and a magnet).

I have access to L/R/GND here, as well as output of its amplifier stage to speakers (positive/negative).

What I want to do is hook up the output of the recording module, over to the L/R/GND of the HeadRush speaker (L/R connected to positive, GND connected to negative), so that I can record at a lower volume and avoid crackles but still play recording at a higher volume. I only need about 10 seconds of recording that's not horrible or even stereo.

Is this feasible? Or is there a better way of chaining? Or should I not do this at all?


texts: How can I measure the frequency of a watch crystal using my oscilloscope?

texts:
I am trying to measure the frequency of a 32.768 kHz watch crystal which is connected to my AVR MCU. This is so that I can fine-tune the crystal's capacitor values to get a correct frequency. However, I don't seem to be getting any output on my oscilloscope (a Rigol DS1052E with the factory probes).

I have tried measuring between both crystal legs and also between one leg and ground and don't get any output. I have set the fuses correctly for the external crystal, and the MCU is working.

Also, even if I could measure the frequency, could I be sure that the measured frequency is what it would run at, or would the oscilloscope probes end up giving me a distorted reading somehow? If so, how can I tune the caps to get a stable 32.768 kHz frequency?


texts: What does the series of circles in a schematic mean?

texts:
I saw this series of 4 circles in the schematic of an Arduino board. Similar circles appear in other Arduino schematics, though I don't think they are Arduino specific (which is why I post here rather than on the Arduino forum).
What do they mean?


texts: I2C slave compatible with SMBus protocol?

texts:
I do have some inquiries regarding using an I2C slave controller (from Arria 10 FPGA).

We are currently assessing MCTP protocol support in our device, whose physical layer is built upon SMBus/I2C, according to MCTP specs.  Our starting point would be to use the built-in I2C controller in our fixed processor inside the fpga.  Our device would only act as I2C slaves meaning it doesn’t initiate any communication.

I understand that SMBus and I2C have mostly similarities in electrical signal level, except on speeds (SMBus is only up until 100KHz clock, while I2C supports higher clocks; but anyway we are just after basic implementation at 100KHz clock so this is not a concern).  However, later on the MCTP specs, it describes the MCTP behavior only in terms of SMBus protocol, like SMBus block write which I don't see exact equivalent protocol in I2C.  It also recommended using ARP, which I think is not specified in I2C and only in SMBus.  So I'm expecting that the MCTP host will be sending me, the device, commands in terms of SMBus protocol.  Now if we have an SMBus controller in Arria 10 this won't be a problem, but we only have I2C, and I'm not sure whether our I2C "slave" controller will understand SMBus protocol.  I've tried to research online but I'm getting conflicting views.  I've also asked Altera but still waiting for their reply.  What I kept on reading is that "SMBus is a subset of I2C".

I'm mostly concerned about multi-byte transactions (block write, read, multi-byte write, whatever their names are), since the host will be sending packets and I will be replying with certain number of data bytes.  Will our I2C controller work with SMBus protocol?  Let me know what you think.


texts: What is a good way of estimating how long a battery will last for powering up a microcontroller

texts:
I know this is going to be a broad question, but I'm looking for a broad answer that can get me a ballpark figure. When building a board with microcontroller, what's a good way to estimate how long a battery will last?

For example, I'm building a circuit with Texas Instrument's CC 3200. One of the requirement is that the microcontroller has to be always connected to the AP, so I'm assuming I need to look at the current consumption under MCU / NWP active profile. For this chip, it widely varies (I think? I'm not too profound on what the test condition mean in page 31 of the above datasheet) from 59 - 278 mA for MCU / NWP on.

Let's say I use a 9v battery to power this on. A 9v battery typically has around 500mAh capacity rating. So does the estimation go something like

Min: 500mAh / 59mA
Max: 500mAh / 278mA

Battery will last between 8.47 hrs to 1.8 hrs?


texts: Differences between Linear and Non Linear WECS models

texts:
I'm modelling a wind turbine and PMSG with uncontrolled rectifier and buck converter. I am currently trying to design a current controller for the current Iq coming from the generator. To do so, i linearized the entire system. I previously attempted to design PI controllers for the systems but controllers that worked for the linear system did not work for the non linear system and vice versa. However, using the "linearize" command in Simulink which- the bode plot generated for the linear transfer function of the system and for the non linear model are exactly the same.

Now I am comparing the step responses of the linear and non linear system, which i am expecting should be the same for a small step (0.5). By stepping the duty cycle of the converter, the following step responses for the linear and non linear system were found. Does anyone have any idea what might be wrong?

N.B. ignore the fact that the response of the linear system starts at 0 and goes negative- i am mostly interested in the amount severity of the drop in current in the case of the non linear system and the time it takes before rising back up again.


texts:
Maybe my first question Dc-Dc converter from 12v Input 400v Output was too broad for what I was actually trying to solve, which is why I am reformating my question.

I want to charge a capacitor (C=0.68μF) at 400v for a CDI (Capacitor Discharge Ignition) System. I have thought to use a dc-dc flyback converter going from 12v, can also be 24v, to 400v. The discharge will be happening when I press a trigger button, which is why I am thinking of charge current, output current for the dc-dc converter, of 10mA.

I have not been able to come with the correct design for this project. Could anyone give me some tips or hints on how to solve this?

Edit: The idea, for now, was using this transformer: Myrra 94094. But thanks to some of your answers, it doesn't look to be the best idea.


texts: What is RF switch used for in a lab equipment?

texts:
I'm only familiar with scopes, DMMs and a little spectrum analyzers.

But I couldn't understand what an "RF switch" is used for particularly in a characterization lab.

Can you give an example of its use and function and describe in layman terms?


texts: How to decide and calculate parameters for track on differential pair?

texts:
I am a bit lost about how to establish the parameters to establish differential pair routing. I am currently trying to route several differential pair and I am a bit new to this. I have searched online some tutorial but I don't find any really explaining easily and out of the theory with simple succession of steps about how to do it

I have downloaded saturn PCB software to see if it can help but I don't understand well how the soft is working because what it ask me to input is typically what I am searching for (it looks it is reverted... !!!)

Assuming the differential pair I am routing is requiring 90 ohm (this is what the hardware guideline say "Route the USB differential pair on the top layer with a trace width and differential spacing tuned to the
PCB stack-up for 90Ω differential impedance ").

So in Saturn PCB I have indicated in target zdiff : 90
Conductor spacing: I don't know (Am I supposed to arbitrary settle this, then accomodate the other parameters ?)
Conductor width: same
Conductor height: this I suppose I need to check my layer stack up. In this case I suppose I have to decide the spacing between top track and ??? first prepreg or core ?

I would really appreciate if someone who have experience could explain their methodology via a "1./ 2./ 3./  4./ points methodology" to be able to achieve any differential pair routing.


texts: Does an accelerometer sensor measure the distance accurately when it is used inside a car? and what is the misjudge percentage when it is compared with its odometer?


texts: Connecting to WiFi at boot on an Orange Pi Zero

texts:
I'm using an Orange Pi Zero as a base for a WiFi radio. The basic operation should be

Boot
Connect to Wifi
Load bash script using MPD/MPC to connect to wifi stream
Set volume
Check potentiometer circuit and adjust volume if needed

So far I have the OPi imaged with armbian (jessie) and have the stream connecting, potentiometer working and audio playing. My issue is getting the board to connect to wifi at boot.

The WiFi will connect when I set it up over SSH using either nmtui or armbian-config however when rebooting the OPi will not re-connect.

Any help appreciated


texts: Are light dependent resistors stable wrt time?

texts:
This question specifically concerns my issues with an ORP12 like:-

I've read the data sheet and I see that resistance changes wrt short time (15 sec).  Also note 1 mentions 16 hours. But what happens after?  Is it possible that the resistance could double (69k to 136k) over the course of a couple of weeks?  I need this question answering in order to rule out other possibilities for my resistance change in an otherwise steady state system.


texts: LTSpice RF transistor 2 emitter "the instance has fewer connection terminals than the definition"

texts:
I am trying to use the Infineon spice model for BFP640ESD (link for library file), but it has two emitter terminals and I'm not sure how to use it since the BJT models have only 3 terminals and I need 4.
Spice code added below:
***************************************************************
*   Infineon    Technologies    AG
*   GUMMEL-POON MODEL   IN  SPICE   2G6 SYNTAX
*   VALID   UP  TO  10  GHZ
*   >>> BFP640ESD   <<<
*   (C) 2012    Infineon    Technologies    AG
*   Version 2.1 November    2012
***************************************************************
* - Please use the global SPICE GP parameter TEMP to specify the
*   junction temperature of the device in your application to get
*   correct simulation results. This procedure is necessary because
*   the GP model does not consider the self heating of the device.
* - TEMP is calculated by TEMP=TA+Pdc*(RthJS+RthSA). The junction
*   temperature TEMP is the sum of the ambient temperature TA and
*   the increment of temperature caused by the dissipated DC power Pdc.
* - RthJS is the thermal resistance between the junction and the
*   soldering point. RthJS for this device is 310 K/W. RthSA is the
*   thermal resistance of the PCB, from the soldering point to the
*   ambient. For determination of RthSA please refer to Infineon's
*   Application Note "Thermal Resistance Calculation" AN077.
* - The model has been verified in the junction temperature range
*   -25°C to +125°C.
* - TNOM=25 °C is the nominal ambient temperature during measurement
*   for the parameter extraction. Please do not change this value.
****************************************************************
*.OPTION TNOM=25, GMIN= 1.00e-12
*BFP640ESD C B E1 E2
.SUBCKT BFP640ESD 1 2 3 4
*
CBEPAR 22 33 2.29E-013
CBCPAR 22 11 7.095E-014
CCEPAR 11 33 2.024E-013
LB    22 20 6.623E-010
LE   33 30 1.519E-010
LC   11 10  6.522E-010
CBEPCK 20 30  4.4E-014
CBCPCK 20 10  1E-015
CCEPCK 10 30  4.4E-014
LBX    20 2 3.607E-010
LEX   30 35 5.524E-011
LCX   10 1  2.452E-010
*
RE1 35 3 1E-03
RE2 35 4 1E-03
*
D1 33 25 M_D1
D2 41 25  M_D2
*
RBLfdb 22 25 1.754
*
R_PW_fbd 41 33 7.5
R_PW_e11g 42 33 2.1
R_sub_fbd 41 5 477
R_sub_e11g 42 5 350
R_CS_npn 55 5 424.1
RSUB 30 5 0.001
*
D3 42 15 M_D3
D4 23 33 M_D4
D5 23 15 M_D5
*
RLDNBL 15 11 10.63
*
Q1 11 22 33 55 M_BFP640ESD
*
.MODEL M_D1 D(
+ IS=3.5E-015
+ N=1
+ RS=6.1
+ CJO=1E-014)
*
.MODEL M_D2 D(
+ IS=6E-015
+ N=1
+ RS=0.01
+ CJO=9E-015)
*
.MODEL M_D3 D(
+ IS=9E-015
+ N=0.9973
+ RS=160
+ CJO =2E-014)
*
.MODEL M_D4 D(
+ IS=3.5E-015
+ N=1
+ RS=0.2
+ CJO =2E-014)
*
.MODEL M_D5 D(
+ IS=3.5E-015
+ N=1.02
+ RS=4.7
+ CJO =3.003E-014)
*
*
.MODEL  M_BFP640ESD NPN(
+   TNOM = 25
+   IS  =   9.658E-016
+   BF  =   557.2
+   NF  =   1
+   VAF =   192.2
+   IKF =   0.09128
+   ISE =   3.626E-014
+   NE  =   2
+   BR  =   246.5
+   NR  =   0.9955
+   VAR =   1.577
+   IKR =   0.004397
+   ISC =   1.27E-014
+   NC  =   1.322
+   RB  =   4.406
+   IRB =   0.0006534
+   RBM =   0.8094
+   RE  =   0.2638
+   RC  =   4.042
+   XTB =   -2.576
+   EG  =   1.11
+   XTI =   0.15
+   CJE =   3.798E-013
+   VJE =   1
+   MJE =   0.1016
+   TF  =   2.172E-012
+   XTF =   1.084
+   VTF =   0.5626
+   ITF =   0.3839
+   PTF =   0.28
+   CJC =   5.346E-014
+   VJC =   0.7186
+   MJC =   0.8649
+   XCJC    =   1
+   TR  =   2E-009
+   CJS =   1.404E-013
+   MJS =   0.07264
+   VJS =   0.4
+   FC  =   0.3
+   KF  =   7.116E-011
+   AF  =   1.7)
***************************************************************
.ENDS BFP640ESD


texts:
Vacuum relay vs solid state
I have an unusual circuit that needs to be designed. What I need to do is mimic two 12volt relays ( in principal anyway ) to control an ac source. The source goes to the common terminals of the two relays. When the relays are energized the ac flows out of the normally open terminal. When at rest the ac source then flows out of the normally closed terminal. This all has to be performed at a rather high rate of speed ( about 20 kHz ). Also the source is high voltage about 2000 volts and about 30 amps. I was considering using a DPDT vacuum tube relay, it will easily handle the voltage and the current.. However they are not designed to switch at a high rate of speed continuously. This is my dilemma. I would like to go solid state but I'm not sure that it is possible. This is going to require a VERY clever individual. Any thoughts?


texts: What is the difference between high-Z (high impedance ) and open circuit?

texts:
I cannot understand exactly difference between them. I am not sure about this topic.
I think high-Z means "temporarily open circuit."
Can you explain the difference to me?


texts: Low voltage cutoff circuit with USB reset

texts:
I am currently trying to design a circuit for a low voltage cutoff. Once the voltage dropped below a certain threshold it should stay low.
When a USB-cable is attached it should reset and start watching the voltage again when the cable is removed.

V+ could be around 2-4.5V

VCC should be 3-4.5V or 0V

The TC54 is a voltage detector which outputs the input voltage as long as it is above a certain threshold. When its lower the output is active low.

By using two npn-transistors in parallel I tried to get some kind of "OR-Gate" that pulls the base of the pnp-Transistor low, when a voltage is applied either the by voltage-detector or the usb-port.
Which in turn keeps the voltage-detector alive.

Could this kind of "feedback-loop" actually work, or do I need to add some kind of hysteresis (for example a capacitance)?
Is R15 needed? The data-sheet states an absolute maximum 5V for the Emitter-Base-Voltage.

Is it okay to put the transistors in parallel?

I had some doubts because I read a lot about the negative thermal coefficient and that because of that one of the transistors would run hot and take all the current.
Does this apply to this case, where the current is so low, that each of the transistors could easily take it on its own?

It would be nice if someone would understand my schematic and could offer a brief feedback.


texts:
I'm struggling with my first real freeRTOS project. I am basically using an ATmega328P microcontroller and an nRF24L01+ radio as a "node". I have two of these nodes and I am using them to talk to each other. I have successfully ported freeRTOS to my microcontroller so that I can use tasks to blink LEDs and to do very basic send/receive of data using my radio driver which I also wrote. The part that I'm struggling with is how to best structure my code and tasks to create something like a network layer on top of my radio driver.

Here were my initial thoughts:

When the radio's data ready interrupt fired, I would set a global boolean variable to signal to my "radio_task()" function to read data from the radios FIFO.
I would have a function called "radio_task()", which would NOT actually be a freeRTOS task, which would check the outgoing queue and use my radio driver (in combination with freeRTOS receiveFromQueue()) to send the front packet on the queue if there is one. This function would also check the global boolean and read a packet from the radio's FIFO if there was one. It would then sendToQueue() this read packet onto the incoming queue.
I would then have an actual freeRTOS called nwk_task() which would have a state machine to do various network maintenance and upkeep etc. Inside the state machine there would  be some calls to a nwk_send() function which would sendToQueue() for the outgoing queue. Likewise there would have to be some receiveFromQueue() calls on the incoming queue which would process whatever packets I receive. Then lastly this freeRTOS task would call my function radio_task()
I would potentially have other tasks running which would monitor sensor data and perhaps also call nwk_send() when certain events occur based on sensor data etc.

I feel like that is not a terrible approach, but I'm running into a few difficulties that I thought I would ask about. Questions:

I've created a typedef for my nwk_packet_t which is a struct consisting of an address, a statically defined array which is the maximum size for a radio packet, and a data_length which says how much of the array is actually used for this packet. How do I make a freeRTOS queue which holds my nwk_packet_t 's?? Also is there a better way to make my nwk_packet_t than using the statically sized array? I thought about using a pointer but then I have to make sure the array that I'm sending isn't overwritten until it's actually pulled off the queue right?
I'm confused about where blocking would/needs to occur. By using the global boolean flag in my data ready ISR I allow interrupts to occur more frequently, but does that mean I need to use portENTER_CRITICAL() when I actually push/pull data from the queues?
How would a more experienced embedded programmer structure the tasks and queues to allow for a network layer on top of my basic radio driver?

Sorry for my severe lack of understanding on some of these topics, this is my first venture into OS level programming. Everything else I've done has been very low level and basic C. Thanks for your help!

EDIT: One thing I forgot to mention is that my radio has some hardware provisions for acking. You can set a message to be auto acknowledged with a certain number of retries and the hardware will handle all of that. However, a message can still fail which you can read from the radio or have the radio trigger an interrupt when this happens. So I would like to have some notion of a message success and a message failure that does some type of callback but I have no idea how to work that into my structure. Any ideas on that would fit in with removing stuff from the queues etc.?

Thanks again.


texts: Circuit diagram for uninterrupted usage of a 12V 1A device using 12V 7Ah battery with auto charging and full charge cut off

texts:
I have a modem  which runs at 12V 1A, also I have an UPS battery of 12V 7Ah. I need to design a circuit so that during power outages my modem works from the battery.

Also, a circuit to charge the 12V 7Ah battery with full charge cut off so that I can connect these circuits so that there is no need to look after it after connecting everything like need to recharge the battery every day. So please help me to set up a circuit.

To connect the 12V 7Ah battery to the modem 12V 1A safely without causing damage to the modem.
A circuit to charge the 12V 7Ah battery with auto cut off on full charge.
Automatically change over to battery so that the modem works on power outage with out disconnection.

Also one thing, the battery can't be connected directly to the modem because the modem is 12V 1A and the battery is 12V 7Ah; also the battery when fully charged will show 13.4V on multimeter, the battery is of type lead acid.

sample battery image http://img3.tradeee.com/up/lilian2010/74108.jpg


texts:
The schematic of a SR flip-flop is the following:

The equation for the output is:

$$Q^{t+dt}=(S+\bar{R}Q)^{t}$$

What I don't understand is that as the output \$Q\$ is given again as an input and the same happens with the \$\bar{Q}\$, doesn't this create a race condition?


texts: How to wire sennheiser headphones to an iphone headphone cable

texts:
I have a pair of these (or something very similar) :

The plug failed so I chopped it off and was hoping to wire it to a plug on a spare pair of iPhone headphones I had kicking around. Both sets of headphones have a button and microphone so I figured it wouldn't be too hard.

I was wrong. The iPhone cable has 6 wires (one white one hiding inside the red/green combo) and the sennheiser only has 4 - white, red and two coppers. I did a very quick test to see if just holding some of the wires together would give me sound in one of the ear-pieces - nothing, though I'm confident both cables are fine.

Is this maybe to do with laminate on the wires themselves? Do I need to connect red to red and a ground? I'm a noob so don't know what a ground does in  audio cabling.

I would appreciate any pointers. My plan is to twist the wires together (like this - youtube) rather than solder. I also have some heat-shrink tubing.

There is a diagram of iphone pinouts here -

here are my cables:

sennheiser
iphone


texts: Flash storage: How do I know the remaining writing cycles without relying on SMART?

texts:
Flash storage such as SSD has a SMART system like HDDs.
But  USB sticks and SD cards lack that.

Optical storage has error/quality scanning that can predict failures early, while error correction is still able to cope.

Is such a quality scan or any other way able to measure the approximate remaining writing cycles for flash transistors?


texts:
Today is my first day on FreeRTOS. I want to use it in STM32F103 for simple task handling as reading data from analog sensor and sending remotely using GSM module.

I want to know what are the do's and don'ts of writing a good task in FreeRTOS? Specifically is it allowed to write a blocking code, for() loop while() loop, inside a task?


texts: What purpose does the capacitor serve in this schematic?

texts: I'm looking at this schematic someone did for daisy chaining a set of 74HC595's and I wanted to know why there is a capacitor put on the pin4/latch and the GND. What purpose does it serve and why is it not required on the other 74HC595?


texts: VHDL subtype constrained by specific values (not range)

texts:
Is it possible to constrain a subtype not by a range x to|downto y, but instead by specific values or combined ranges, like it is possible with the choices in case?

It might look like this:

subtype validValues is integer (0 to 21 | 42 | 1337 | 9001 to integer'high);


texts: Can USB 3.0 tracks be closer together than 5W if they're quite short?

texts:
I am currently laying out a space constrained PCB which contains some USB 3.0 Superspeed differential pairs. These USB signals are confined to the PCB, going from a Cypress CX3 chip to a USB 3.0 Hub chip. They do not go to or come from a connector. The signals are approximately 30mm long from start to end.

According to the advice, the Superspeed pairs should be separated from each other by at least 5x the differential pair spacing. (This is known as the 5W rule)
Since the signals are fairly short, and do not go through a connector or cable, would it be possible to push them a little closer than 5W? Say, 4W or 3W?


texts: Requirements for Integrating Thunderbolt 3 Into Product

texts:
Based on the bandwidth and relatively good availability of Thunderbolt 3 ports on PCs we are considering incorporating a Thunderbolt 3 interface into a new product.

My understanding is that the thunderbolt can interface a PCIe endpoint.

Intel has the DSL6340 controller which is available for purchase from various vendors, but I haven't seen any accompanying development materials.

Is it possible to obtain development support material for Thunderbolt 3 if it's for a low-volume product? Is it feasible for a small company to develop a Thunderbolt 3 product?


texts: Why does this detector detects wifi signal as well?

texts:
This is the link
https://www.seattleu.edu/scieng/ece/laboratory/cellphone/

Why does this circuit detects wifi signal as well? Is it possible not to detect the wifi signal?


texts: ESP8266 doesn't boot properly if GPIO pin connected

texts:
I'm using an ESP8266 board to control a relay via a transistor like this:

simulate this circuit – Schematic created using CircuitLab

However, when I boot the ESP8266 with the GPIO0 pin connected as shown, the blue LED is on constantly, as if in a constant reset or a flash mode. If I connect the GPIO once the boot has finished, it works fine. Does anyone know a way around this issue?

I am using the Arduino IDE to program the board with this code:

#include <ESP8266WiFi.h>

const char* ssid = "SSID";
const char* password = "PWORD";

int ledPin = 2; // GPIO2 of ESP8266
WiFiServer server(80);//Service Port

void setup() {
  Serial.begin(115200);
  delay(10);

  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);

  // Connect to WiFi network
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.print("Use this URL to connect: ");
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  Serial.println("/");
}

void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }

  // Wait until the client sends some data
  Serial.println("new client");
  while(!client.available()){
    delay(1);
  }

  // Read the first line of the request
  String request = client.readStringUntil('\r');
  Serial.println(request);
  client.flush();

  // Match the request

  int value = LOW;
  if (request.indexOf("/LED=ON") != -1) {
    digitalWrite(ledPin, HIGH);
    value = HIGH;
  }
  if (request.indexOf("/LED=OFF") != -1){
    digitalWrite(ledPin, LOW);
    value = LOW;
  }

  //Set ledPin according to the request
  //digitalWrite(ledPin, value);

  // Return the response
  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println(""); //  do not forget this one
  client.println("<!DOCTYPE HTML>");
  client.println("");

  client.print("Led pin is now: ");

  if(value == HIGH) {
    client.print("On");
  } else {
    client.print("Off");
  }
  client.println("

");
  client.println("Click here turn the LED on pin 2 ON
");
  client.println("Click here turn the LED on pin 2 OFF
");
  client.println("");

  delay(1);
  Serial.println("Client disconnected");
  Serial.println("");
}

Thanks.


texts: Having trouble finding Vo, V1 and V2 in this circuit (not homework)

texts:
I'm working out textbook examples to get better at beginner analysis.  I'm having trouble with this circuit.

simulate this circuit – Schematic created using CircuitLab

Steps I've tried:

1) 10k*20k / 30k = 6.6666...k ohms
2) 5k*10k / 15k = 3.3333...k ohms
3) those are now in series, for 10k ohms equiv on the left side
4) from the right, 8k+4k = 12k ohms
5) 144k / 24k = 6k ohms
6) 6k + 4k = 10k ohms equiv. on the right side
7) now the 3k ohm resistor is in parallel with both the 10k ohm equiv resistors
   on both side, so I know the voltage across both 10k ohm resistors is 16V.
   Calculating current, I find that current is 1.6mA across each combined 10k
   ohm resistor
8) now, splitting the 10k ohm resistor into the 6k and 4k in series, i know they
   both share 1.6mA current; thus V1 = 1.6mA * 4000 ohms = 6.4 V.

I stopped here because I got the wrong answer.  Will someone please help me figure this out?


texts: In AC RL circuit why does current increase when voltage decreases?

texts:
We know that the inductor creates an emf trying to oppose the change in ΔΦ. For an AC LR circuit I found the following diagram.

My question is why doesn't the current reach its peak a little earlier than π/2? When the voltage is at its peak I suppose the emf is smaller than the source voltage so the current keeps increasing, trying to flow through the inductor. The emf is big at this point based on what I know for the DC RL circuit and decreases through time. We can tell from the diagram that the current increases until π/2 when the inductor comes into play to oppose its decrease this time.

However, I can't understand why this is not happening earlier. I get the increase in current at first when voltage is at maximum value but when it gets really small the current has already reached the maximum value for that particular voltage. So won't the emf change polarity at that point?

In case I wasn't clear I give you this example.
Say we have a DC LR circuit. Time has passed and the current has reached its maximum value given by Ohm's law. Now I disconnect the source and connect another source with a lower voltage(this happens instantly). The current will slowly decrease because the emf tries to keep it constant. So the decrease starts now and that is because the voltage is lower.

Isn't there a time before π/2 in the AC circuit when voltage is lower than the voltage given by Ohm's law for the current at that moment?


texts: Calibration of reading of current measuring cicuit

texts:
Ok ,I'm making a small current meter device
I was able to take the voltage coming from a "shunt resistance " which is a current transducer that gives me an specific analog signal that proportional to the current passing in it  , I take this signal into ADC , so I facing a problem of calibration

My question is :
-The available methods to calibrate the reading
-Is there some methods that I can make it programmatically  without the need for a reference(external device )  or human interference ?

My goal in accuracy for now is 1% in readings .
I'm measuring AC current.
Range from 0.5 A to 80 A . Heat is not a problem .


texts: 2 simultaneous voltages from a transformer

texts:
I need a step down transformer that can give me 2 voltages simultaneously.
Primary will be 380vac and secondaries will need to be 24 vac and 12 vac. Instead of using 2 transformers, I would like to have a single transformer that supplies the 2 outputs as required.
I do not want to activate a switch or change any wiring. I need those 2 output voltages simultaneously at all times. I will never need one without the other.
Does anyone know if such a thing exists?


texts: What happens when I put a charge inside a conductor that is already in static equilibrium?

texts:
I understand how, when a neutral conductor is charged, the charges will repel each other and after the relaxation time will all be distributed in the surface of the conductor.

My question is: after that period, the electric field inside the conductor will be zero, so if another charge is put inside the conductor, how will it get to the surface? It must get to the surface somehow, because the charge inside the conductor must be zero, but how is it going to do so if the electric field is zero?

I came out with one idea of how it could work, but couldn't base it on textbooks. Even though in the beginning the electric field is zero in the inside, since the electric field caused on the outside charges by the inside charge isn't zero, these ones would get "pushed" and the distribution would be "messed", momentaneously, causing an electric field in the inside, that would finally "push" the inside charge to the outside. After that, the distribution outside would be one that allows us to say the electric field in the inside is zero again. The problem here is (appart from the fact that this doesn't base itself on any textbooks) if the charge is placed perfectly in the middle of the (let's consider a sphere for simplicity's sake) sphere then the inside charge won't be able to unbalance the distribution on the outside, because the electric field caused on the outside charges won't have a tangetial component, but only one that is perperdicular to the surface.

I am very curious about this and I am eager to clarify any points that might be unclear in the question. I looked up many physics books but couldn't find anything about this specific case I made up. Maybe it is physically impossible to place that charge in the inside after static equilibrium has been reached, or maybe it is possible and there is indeed a mechanism for the charge to be directed to the surface of the conductor. Anyway, I just wanted a well based answer, because mine are just guesses.

Thank you very much


texts: I have two LDOs that convert different input voltages into the same voltage. I'm not sure how to safely connect the outputs together so they become the same signal and can be both be used to power the board, is it as simple as just connecting the outputs together since the voltage is the same? Thanks


texts: What kind of tool is used to record a voltage over time to a PC file like a waveform?

texts:
I don't have any training but am doing some hobby electronics. I would like to record a change in voltage over time, sampled at around 100+ kHz. Ideally, I'd like to record around 20-30 min of two different channels, so I guess that works out to be at least 240 million samples. I'd like to view this recording on my Windows computer similar to a stereo .wav PCM waveform. (In fact, if I could save it as a .wav file, that'd be ideal.)

I considered simply using a sound card to make this recording, but this seems to not be possible with a DC signal.

Is this something that a digital oscilloscope can do? Or is there a tool designed for this specific task of recording to a file, similar to the line-in on a sound card? Converting to digital and streaming over USB to record on a PC seems to be what I'm ideally looking to do.

Edit: Giving some context as requested... This is for a latency test. I am wanting to record a variable latency of a video game system plus an HDMI adapter. Using a photodiode I can create a voltage stream that will show when the result appears on screen and compare it to when a button was pressed. (Hence why two channels are needed.)

Thanks!


texts:
i have RaspberryPi, SSR-25 with triac inside.
RaspberryPi GPIOs are 3v3.
It is written that it does work with the voltage from 3V, however 3v3 does not trip the triack - 5V does.

Is it safe for Raspberry,
to connect both 3v3 and 5v across DC side of this SSR,
and turn GPIO 3v3 OFF, to get 5V across SSR and send it signal further?

I want to make this solution, as simple as possible.

Thanks


texts: How to add components in tina simulation schematic editor that are not available in TINA library?

texts:
I am using TINA simulation software free version for dc to dc buck converter design. I want to draw the below schematic myself in TINA platform for simulation purpose. But while using TINA editor ,I am facing difficulty i.e. I am unable add components like transformer with extra auxiliary winding ,UCC28C40 ,NMOSFET .These parts are not included in the TINA library .

So how should I add these components in  the schematic?


texts: What kind of socket for a 5-position 0.067 pitch part?

texts:
What kind of socket would I use to connect a 5-pin 0.067" pitch part (the Murata OKR-T10-W12) to a piece of normal 0.1" pitch stripboard?

Googling "0.067 5-pin socket" gets me hits for CPU sockets and the like.


texts:
I am working on a project where I will have 2 or 3 sensors inside a house, all sending data back to a central sensor/hub in a star network configuration. This central sensor would then buffer all the data from others and itself and send it across a LoRa network to a central server once a day. The whole system has to be ultra low-power.

At the moment my plan was to use a non-LoRa wireless network within the home (with a CC1310 or nRF51822) and have one device with LoRa capability (SX1272) to act as the hub. I wondered though, would it be possible to just use LoRa as the main network within the house too and replace the wirelss SoC with a different non-wireless low power microcontroller?


texts: I am trying to implement a circuit that can detect windspeed using a turbine. To measure windspeed I need to detect it as a voltage signal. I was thinking of using a photo-interrupter circuit to measure a voltage sinusoid but am not sure if it would work?


texts:
I read an article from wikipedia about freewheeling (flyback) diode which is used to drive a relay. I understand it but I have four questions. Would you give me a hand, please ?

1- Why does the coil change its polarity ?

In figure 1 the positive terminal of the coil is the upper terminal (at node 1), but in figure 3 the positive terminal of the coil is the lower terminal ( at node 2). that means it discharge in the opposite direction. If it was a capacitor the polarity would not change.

2- If I apply AC to a coil, Does the voltage spike happen each period when the voltage is zero ?

I read that the coil makes a voltage spike when we turn off the supply. does that mean the coil make spikes at the arrows of the following figure?

3- Why don't we put a diode for each inductive load such as motors in children toys .. etc. ?

4- Can I put an LED rather than a diode ?

Thank you very much,