texts: How to remove noise signal on the interrupt pin of micro controller

texts: My system is interrupt driven, but sometime due to noise signal generates, micro controller treats this signal as an interrupt which is wrong so how can I remove that signal and allow controller to jump in ISR when and only when original interrupt signal will generate. I am using TM4C123GH6PZ controller


texts: DC motor speed control -> motor heating up too much

texts:
I have 90V brushed DC motor which I try to make to turn 100-500rpm with PWM controller (555 based, 100Hz). Otherwise it works but the motor heats up so much that I can not touch it with hand. I think if I continue, it will burn.

I tried it with 70V DC (can't get higher voltage from my 3 bench power supplies), it draws 1.2A and with 50% duty cycle the rpm is roughly 200rpm with the load. Little bit difficult to measure the load but very roughly it's max 0.25Nm.

I thought this is the way to control DC motor so I wonder what's going wrong..? It the load too much for this motor, does 70V (instead of 90V) make the difference, would higher PWM frequency help...?

Thanks,
Tipo


texts: Accuracy of RMS of sine measured from N samples of ADC conversion

texts: I am sampling a pure sine wave for 1mS at 200nS conversion rate over a 12 bit range, getting 5000 samples. I need to know how accurately I can determine the RMS value of the sine wave. More generally, for a full scale resolution of M bits over N samples, how accurate can I get the RMS amplitude? [I should add - the frequency is 125kHz ie 8uS period]


texts: Show different colors using RGB LED strip and Arduino

texts:
I am a beginner, I am following this post to program RGB LEDs (smd 5050).

I want few specific LEDs to glow in specific color while other LEDs are glowing in other color. Need help in doing this.

I have Arduino UNO board with me.

EDIT: Atleast, guiding in right direction will be appreciated.

LED Strip image


texts: Idiomatic way to control output voltage of buck/boost converters using microcontroller

texts:
I'm trying to design an appliance that efficiently regulates power to some Peltier elements.
The manufacturer states that optimally, you should drive these with regulated voltage and not PWM. They have a non-linear cooling coefficient depending on dt and current supply, so I would like to program that logic in a microcontroller (Arduino) and make a variable power supply essentially (0-7V., 40W max, 4W common)
However, most prebuilt power supply units seem to only have a potentiometer to dial in output voltage. My question thus is, how can I control the output of such a power supply with a microcontroller? I guess I could hack that with a digitally controlled resistor. It seems backwards, though.
Perhaps I'm missing something here, to me it seems like a common problem but I'm a programmer by trade and don't really have much electronics experience.
Ideally I wouldn't design the entire power supply from scratch and just buy something that exists, although I can see how the problem could be solved by PWM + MOSFET + filter. That would basically be a buck converter driven from the Arduino, I guess.


texts: Altium Designer 10 - How to make track connected to pad rule

texts: Does anybody know how to make a rule in Altium Designer on a track connected to a pad? Now I'm able to make rule on pad and on track separately, but sometimes I need to make a rule on a track only in the point in which the track is connected to a pad, and I don't know how to do it.


texts: Have 60A 220V circuit, want to use one 110V leg of it. Can i?

texts:
I have an 220V air compressor (30A) in the attic of my garage.

It has a 110V automatic drain valve connected to it.

A the breaker box downstairs I want to be able to turn the power off to BOTH.

Ideally I could simply turn off the 220V circuit (the compressor is the only load).

The 220V circuit is single phase and the receptacle is a NEMA 14-50.

It is my understanding that this is a split-phase 3-wire system.  It's really 4-wires:  Ground, Neutral, Leg 1 (110V), Leg 2 (110V).

What I want to know is if there is any problem with me using one of the two legs (plus ground & neutral) to power a 110V outlet for the automatic drain valve.  I'm 99% sure there's no technical problem.  I just want to double check on any safety issue or something I may not be aware of (as a DIY).


texts: Is there only one SMBus on PC Motherboards?

texts:
I have connected two wires to the SMBus clock and data lines of my motherboard (manually soldered via wires, because there is no header). I wish to interface this bus to my microcontroller.

I hooked these up to my scope, and they show the correct 3.3V or thereabouts (this seems to me that the wires HAVE been connected since there is a pullup).

I can read and write to this SMBus via python-smbus on linux. The same SMBus even picks up the SPD eeproms on memory modules, so THIS smbus definitely works. But I cannot see any of this activity on my scope.

Is there only one SMBus on PC motherboards? Or are there multiple, and so I am hooking up my wires to the wrong places?

My Motherboard is an ASRock X58 Extreme 6 (Southbridge is ICH10R)


texts:
One of the students at my uni has laid out a PCB with a TPS560200 step-down converter. However, instead of 5V it only outputs 0.9V. I've checked the feedback resistors and they are correct*. The problem happens on multiple boards.

My initial guess was that the layout is wrong. Suggested layout is:

And this is what was produced:

My guess is that the output inductor is too far away. Would this be the likely cause? What else should I suggest to change or troubleshoot?

Update*

It turns out the feedback resistors were all swapped.


texts:
I would like an amplifier that can amplify AC (a square wave at ~50-100kHz) and DC. I would like to get a stereo audio amplifier and have each channel drive a different coil (one for the AC, one for DC).

The input (for the dc amp) will come from an a/d converter and vary from 0-3v at a max of ~30hz (although random not sinusoidal) and I'd like the output to go up to about 24 volts 1amp. I have 12v & 24v power supplies but am happy to get more.

Can an audio amplifier do this or be modified to do this? If yes, is there a specific type I should get?

I was originally planning to use an op amp, but mine can only do about 10W and an audio amplifier would be so much more convenient.


texts: Help for a comparator circuit immune to noise with an LED indicator

texts:
I have the following circuit which uses an LM2903 comparator. But Im not sure if it is designed well enough, and not sure about the open collector output is used correct:

THIS CIRCUIT UPDATED AND MODIFIED PLEASE SCROLL DOWN AND SEE MY EDIT AT THE END OF THE QUESTION

I want to modify the above circuit for two types of inputs from two types of pulse outputting devices.

Input to the circuit will be two types of pulse trains coming from one of the two types of devices. The devices will be either powered by 12VDC and which outputs 12VDC pulses or will be powered by 24VDC which outputs 24VDC pulses. Pulse freq. range is 5Hz to 800Hz. I want the device and the comparator circuit to be powered from the same power supply.

And as I tried to clarify the pulse outputs of the devices will go to the circuit as an input.

I want to modify this circuit in a way that:

1-)The output will be 0 to 5V or 6V pulse, for both 24V and 12V cases.

2-)I want the circuit has a large hysteresis in Schmitt trigger configuration and immune to noise(i.e. output as clean as possible).

3-) I also want an LED to blink and indicate whether there is output by not effecting the pulse freq. or introduce noise to the pulse outputs.

I would be glad to have your version or suggestions for this.

EDIT 1:

To add large amount of hysteresis I had to use the inverting input.

And to use an LED indicator I followed analogsystemsrf's suggestion.

Below is the circuit so far:

(click to view the image)

Now I have large hysteresis but LED doesn't go off.

But now I have the following problems and worries?

  How can I employ an LED so that I don't introduce noise?

  And what do you think about the capacitors in this circuit? Do you
  recommend additional ones?

EDIT 2:

With analogsystemsrf's suggestion I modified the circuit again.
When I did that, I had to rearrange some resistors to increase hysteresis.
I also used 8V zener. Here is the last version:

(click to view image)

And here is the LED current(ringing due to LTSPICE?).


texts: Interfacing of Proximity Sensor with Arduino

texts: I want to interface OMRON Proximity Sensor E2A-M12KN08-WP-C1 2M with Arduino Uno. How do I interface it with the Arduino? Also, where will I find the relevant starter code? I am new to this and I would appreciate any help.


texts: LM35 connected to amplifier unexpected output

texts:
I am trying to connect the output of a temperature detector LM35 to the input of an op amp. The op amp will later be connected to an ADC. The goal is to amplify the signal between 8C (80mV at the output of LM35) and 40C(400mV at the output of LM35). All values under 8C(80mv) should be 0 and what's over 40C(400mv) should be 5v at the output of the op amp.

To implement this I used TLV2252 as a differential amplifier. The fomula:  Vout = (VoutLM35 - 80mV) * R2/R1.

The output of the op amp should increase or decrease with 156mV for each degree in the temperature (LM35 has the output 10mV for 1C).
The problem is that between 10C and 34C the circuit works as I expect but as the temperature approaches 40C or 8C, instead of having 156mV variation at the output I have a smaller one.
For example:

-At 38C I get 4.58V at the output, at 39C I get 4.69V (a change of only 120mV). Even more, from 39C to 40C the output increases only by 100mV.

-From 9C to 8C the output decreseas from 190mV to 110mV.

Why don't I get 5V at the output when the temp is 40C ((400mV - 80mV) * 15.625 = 5V ).

Thank you!


texts:
The below circuit is 12v Input & 5V max@3Ampere output.

The work of the 7805 is only to open the base of the transistor.(and naturally regulate that voltage at the base to 5v)

What about efficency, how efficent is this circuit?

The transistor he uses is a 2N3055(15A)

As the 7805 has only to open the Base i guess this circuit is a little more efficent than the 7805 itself. If that is correct, using it for a battery powered project, could i use let's say something like a 2n2222 or 2n3904 to get a slightly more efficent powersupply (but decreasing the Amperage)?

  Normally the 7805 is only 20%-21%(12v) efficent so if myproject needs
  100mA the heat it needs to dissipate is around 2Watt

(i read that somwhere yesterday)

I ask because apparently the high efficent switching converter suffer from ripple & noise, but also cost more. And this could increase slightly the battery life & decrease the cost.

notes:

i could hook up multiple transistors and so get multiple 200mA/500mA regulated 5v sources, depending on the transistor. (2n2222=500mA,2n3904=200mA)


texts: Multiplexer for low-voltage measurements

texts:
How does voltage leakage (or cross-talk) from a mux affect low-voltage (voltages on the range of 10s of microVs to mVs) measurements?

I am building a measurement set-up consisting of a Keithley 2400 sourcemeter and two thermocouples (TC). Basically, I heat my sample (resistances vary from tens of ohms up to Mohms) and measure voltages (on the order of 10s of microvolts) with no current, and the idea is to use a multiplexer to switch connections to the keithley.

I measure voltage across the positive and negative legs of TC1, voltage across the positive and negative legs of TC2, voltage across the positive legs of TC1 and TC2 and voltage across the negative legs of TC1 and TC2.

I want to use an analog multiplexer like CD54HCT4052 or CD74HC4352 instead of mechanical relays because they are faster. However, I am very confused if the accuracy of measurement will be affected. Using mechanical relays, I don't have to worry about things like leakage current ("crosstalk"?). What is the difference between leakage current and cross talk?

Maybe since I don't fully understand leakage current, I don't fully understand how leakage current could affect the voltage measurements. In this video from TI (minute 5:21), they calculate an offset voltage that is dependent on leakage current and source resistance. For my samples with high resistances (order of 1-10 Mohms), this offset voltage could be on the same order of magnitude (tens of microvolts) as the voltage I am measuring, so using an analog multiplexer would not be appropriate, right?

Finally, I know analog multiplexers are faster than mechanical relays, but what is the name of "response time" in the datasheets?


texts: Is there a relationship between voltage and State of Charge of a NiCd battery?

texts:
When a NiCd battery is charged, it can go above it's nominal voltage per cell of 1.2 V, typically up to 1.5 V per cell.
How fast does this voltage go down to its nominal voltage if no load is connected?


texts:
One-time programmable (OTP) fuses are common in ICs. How are they typically implemented, on the silicon level? I know that they generally work like larger fuses, i.e. they can be blown but not repaired, but how is this actually accomplished when thousands need to be fit in the die area (e.g. Intel chipsets)?

Is there a difference between how they are implemented between low-power cheap microcontrollers (which might have a few OTPs for lock bits) and high-end x86 chipsets (with potentially thousands of OTPs to store manufacturing settings and even entire RSA keys)?


texts: In production, is there a significant difference between QFN or TQFP components other than space?

texts:
When producing a run of PCBs, does it matter if I choose QFN or TQFP components? Say, I want to have 1000 boards manufactured with an Atmel AVR that is available in QFN or TQFP packages. The QFN package is of course smaller, but I have enough space on the board, so that is not an issue.

For prototypes, the TQFP is easier to handle because I could even hand-solder them, if a reflow oven and stencil is not available. But for automated production, this should't matter, or does it?

For instance: would a PCB manufacturer recommend to use QFN because they are easier to handle by the pick-and-place machines, resulting in a price cut?

The difference in component price appears to be small, too.


texts:
In SPI, I have a few questions...

I understand how bits are clocked through, but how are bytes are delimited?

Is the slave select pin only required for turning the data output high impedance? Or is it also required for delimiting bytes/words?

Also: I got the impression from what I've read (PIC16f74 datasheet) is SPI can be 3 wire, and there are addressing modes which I'm so confused about I think I'll pretend I didn't read for the moment!

I'm just interfacing a PIC16F with 8 bit flash memory Atmel AT45DB011D, so nothing else on the SPI lines. It also has multi-byte commands, so how does it delimit those?

SPI and using the flash chip are  totally new to me, any quick-start guidance would be great!


texts: How to provide power to case fan and light bulb with RPi and relay?

texts:
I want to try to build a simple, straightforward RPi setup to control a incubator, and to provide a web interface to control it. Background--I'm a software girl, not really any experience with circuitry or hardware, but I can follow tutorials.
I'm looking at the following BOM:

Raspberry Pi 3 B+
SHT31-D Sensor
5V Relay Module
Light bulb socket
Case Fan

From a software dev's point of view, I've got my input (SHT31-D sensor), and I've got my outputs (Relay, leading to the lightbulb socket and the case fan). Cool! But what I'm trying to sort out is, where does the power come into play? All the tutorials I've found for basic projects like this seem to have the Pi being powered via the relay somehow, but I'm also seeing a ton of warnings about AC vs DC and the need for resistors.
I had thought that the relay would get its own source of power, and the Pi would control which devices receive it by toggling the relays on and off. That doesn't seem to be the case though.
My questions are as follows:

Could someone help me with the wiring diagram?
With these items, is there anything I need to add to the BOM to make this work?
Am I able to power the Pi on its own via the usb ports like I would if I weren't hooking it up to the relay? Why or why not?


texts: Control power of several devices from an ESP32

texts:
I need to control the power (on/off) of several devices (all at a time, not one by one) from the output of an ESP 32.

So, the goal is to turn on/off the 5V power supply for :

1 LED (using a 270 ohm resistor) : about 10mA
8 "ITR9608" optointerrupter (each using a 270 ohm resistor) : about 8x10mA
8 "SG90" 9G mini servo : about 8x100mA max
1 "MCP23017" : 8 LED outputs, 8 sensors inputs : about 200mA max

So the total should be 1.1A, maybe should say 1.5A as a security factor ?

Are these calculations correct ?

This circuit will be controlled from an ESP32 dev board : it's a 3.3V outputs, about 40mA max.

I've found this circuit : http://www.instructables.com/id/DIY-Motor-Driver-With-ESP32-Controller/

Which kind of circuit should I use ?

A switch using a TIP120 like this ? https://hackaday.com/2017/11/23/building-a-skyrim-quest-marker/
A NPN transistor like this ? http://www.instructables.com/id/DIY-Motor-Driver-With-ESP32-Controller/
A darlington array like this ? http://www.ti.com/lit/ds/symlink/uln2803a.pdf

I'm a software enginner, but a newbie to electronics, so I'ma little lost in front of all the switching circuit examples that we can found on the internet...

Thanks


texts: Display Double Digit Numbers on 2 seven segment displays

texts:
I'm making an Arithmetic Logic Unit(ALU) for an assignment and I'm on a point. So according to my circuit design on the link shared below, I am able to output 1 digit of my alu. It is a 4 bit ALU so the maximum output can be a result of an addition i.e. 9+9 = 18. This is where my problem is.

The correct output is shown until 9 on the 7 segment display. After that, random gibberish is shown. I added LEDs to see the binary output to check if the correct output is received in my simulation.  Since there are only 4 bits, the output on LEDs also goes maximum to 1111 (for output 15 in decimal). After that it is reset to 0000 for 16 and starts all over again.

Can anyone please guide me with the correct approach to take here? How can I make 2 7 segment displays show my correct output in decimal? so that until the output is less than 9, the first 7 segment shows zero, but as soon as the output goes to 10, the first 7 segment displays a 1.

Help is much appreciated.

View post on imgur.com


texts: Advice Needed On Removing Stubborn Circuit

texts: I'm new to soldering and I've done some research on what I need in terms of material and tools and what I need to do in terms of removing and replacing a circuit. The circuit I'm replacing is a Laptop (ASUS g53sw) power jack. This component has 5 connections onto the circuit board and while I've been able to remove a good bit of the existing solder with a wick and flux I'm finding this component is still stubbornly stuck to the board. I'm in need of some good advice on how to remove this as I want to avoid damaging the system. I've read a number of articles and watched some good videos but I still need some pointers as I don't doubt a professional could handle this.


texts: As I understand it most load cells (all?) are only approximately linear. To improve the linearity would a 3 point calibration be sufficient? For example, at no load, half load and maximum load. If so, what kind of linearizing equation or technique is used?


texts:
I am working with an older version of Altium (V09).

I have this popup every time I want to move a part in a PCB doc.

I have the sch and the pcb open and I changed some parts in the sch and to update in the pcb, you need to delete the 'old' part and then update the pcbdoc by clicking Design > Import Changes From...

Then click Yes on the failed to match popup:

And then I click execute changes and this popup comes:

I waited for more than 20mins and then clicked cancel but then the Comma expected error pops up every time I try to move something.

I have tried closing Altium and opening it again. But this didn't help. I have not tried uninstalling and reinstalling, but I would like to avoid that as a solution.

Any ideas on how to fix the comma expected error?


texts: What is the point of inverting RAM output?

texts:
The 74LS189 is a 4 bit RAM IC. The datasheet specifies that the output of the chip is inverted. Thus, if you put 1011 into address 1, when you read back address 1 it will output 0100.

Most of the time, it makes sense why certain chips have certain inputs/outputs inverted, but for a RAM chip, I cannot see any reason that you would want to get any data out other than the data you put in.

Is there some practical reason that the outputs are inverted?


texts: Why is the Capacitor Inductance Positive in Transfer Function?

texts: When solving AC circuits capacitive impedance is always negative. But when finding a transfer function (either the input voltage or input voltage) the capacitive impedance is left positive like in the circuit shown. Why?


texts: CR2032 vs LIR2032 vs Capacitance Battery

texts:
I have an Android TV Box device that does not retain the date and time. Turns out there is not real time clock backup (RTC battery). There are 3 options to solve this.

Capacitance battery
CR2032
LIR2032

How effective is a capacitance battery compared to other 2 options? I am looking for something that I would not need to replace till next 3 to 4 years once installed. I have installed CR2032 in one of the other Android device that I have. It has been working fine for about 10 months now but I highly doubt it will last for 3 to 4 year though.

I am not sure how quickly would the capacitor drain if the device does not get power supply for a day or two, or will the charge last till two days for that matter.

I did a quick search but could not find a comparison anywhere.

Which would be the best option out of the 3? Or is there any option?
If capacitor, then what would be the specs.?
If LIR is the way to go then do I need any other external circuit for it?


texts: Voltage Controlled Voltage Source Circuit Analysis

texts:
I don't know what I'm missing with the analysis of this question. Obviously I know that there's no voltage through the 105k resistor. I know that the current from the VCCS is given by the input voltage times the gain factor.

However, I would have assumed that, based on this, the current from the VCVS would have been 1.003 * 10mS = 0.001003. Ltspice tells me that the current generated is 4.8mA. I can't see where this is coming from. I've probable just stared at it so long that I've over complicated it to all hell. Any help is appreciated :)

Ltspice circuit and dc op values found here:

EDIT: Typed VCVS by accident!


texts: Calculate differential amplifier's input impedance

texts:
How does one calculate the input impedance of a differential amplifier?

Since the input impedance of an op-amp is very high, the input impedance for V2 should be R2 + Rg. But what would be the input impedance for V1?


texts: Holtek keyboard controller working with reversed diode

texts:
I am confused at a mistake I currently have in my setup. I am using this Holtek keyboard controller. Note how the letter Q is produced by connection between R0 and C1 (page 19). According to the datasheet, R0 is pin 6 input, and C1 is pin 20, output.

Now, I have a matrix where the Q button is connected to the above R0 and C1, however there's also a 1n4148 diode in series with the button that is oriented from R0 to C1. I would expect this not to work, because C1 is an output pin during the matrix scan, and R1 is an input pin. The diode is reversed with respect to the flow of current (from C1 to R0). Strangely enough, it does work, and this really is the core of the question.

Is there something in the datasheet I am misunderstanding?


texts:
Ok, so I'm a newbie with electronics and am currently attempting to do a school project that involves using a blank PCB (Idk if thats the technical term), and I don't really know how to put the various components onto the board to match the schematic. If anyone can give me advice on how to place the pieces on the board, I'd be very appreciative. Any helpful advice is great! :D Thanks!

This is the kind of board I'm using:

This is the schematic that I will be following:


texts: DSPIC30F4011 - Pin labled as "Alternative", can I use it?

texts: I am using a DSPIC30F4011 PIC ( datasheet ) to send commands to three devices (one Bluetooth, model RN42 and two LED Drivers, model TLC5947). In the data sheet for this PIC (on page 13), it has three output pins listed. One of these is listed as being "Alternate" Receive. I want to know whether I can also use this pin to command one of the three devices.


texts: Is it possible for a SPI slave to talk to other slaves?

texts:
I'm developing a device that will have a flash chip and a RTC on the same SPI bus, selected using two different select lines. I also have a front panel for this device that needs to access these devices and is currently wired up to a UART, but I'm thinking of making it also an SPI device so I wouldn't have to use the extra pins.

My basic question is this - could I somehow have the front panel MCU, which will be an SPI slave, talk to the other slave devices on the bus somehow? If not, how would I be able to achieve this? I'm thinking about doing this by re-initializing the SPI bus by causing an interrupt on my main MCU, but I'd rather first see if anyone here knows if I can do slave to slave SPI comms.

Thanks for any help.


texts:
I try to switch a 12V non-inductive load drawing 400-500mA with a IRF3708 Logic-Level-MOSFET with the 5V from an Arduino.
I am new to MOSFETs but I simply cannot find my mistake. I think I fried some MOSFETs using the 5V because Rds(on) was too high (3-4Ohm) and this resulting in too much heat which killed the MOSFETs. I hope this conclusion is correct.
But the datasheet states that at 4.5V Ugs Rds(on) should be in a 9.5-13.5mOhm range. Even if it may be optimistic I don't get why it is in the Ohm range and not even near the values in the datasheet.

What am I understanding wrong here?

Schematic:

simulate this circuit – Schematic created using CircuitLab

Circuit:

Calculation of Rds(on)

simulate this circuit

With a load of 1k my Amperemeter gives me a current of 11.8mA @12V with 5V applied to the gate. This equals a series resistance of 1.0166kOhm. This results in a Rds(on) of 1.66Ohm. Ok it is lower than my wrong measuring but still a lot higher as in the datasheet. If 500mA would flow like in my application this  Rds(on) gives an UDS of 0.664V which result in 265.6mW of heat at the MOSFET. Correct?


texts:
I have to solder a microcontroller that belongs to an Arduino Uno to a PCB. The Arduino uno uses the Atmega328p which has 28 pins. On the pcb I have, i see only 27 pins for the microcontroller.

Could i still somehow be able to place the 28 pin microcontroller on this PCB? Or should i make a new PCB with the 28 pins for the microcontroller?

Doing some research i found this footprint package:
https://easyeda.com/component/ATMEGA328P_PDIP_EZ-BbicICwO6

I also never knew a 27 pin microcontroller existed or the footprint at least..

Thanks!

P.S I dont need all the 28 pins for the project.


texts: How does an accelerometer interpret g as ( +9.8 or -9.8 )

texts:
I am working with MPU6050 (accelerometer + gyroscope). Concerning about the accelerometer;

Do these sensors(accelerometers in general) uses g as 9.8 m/s^2 or - 9.8 m/s^2 ? (Is there a standard/convention about this)

When I accelerate it in +x direction for example, it gives me a positive multiple of g, so I conclude that g should have be taken as positive.

But wanted to be sure by asking.

You can also clarify for me that whether it measures gravitational acceleration or the acceleration because of the normal force while standing horizontal(xy plane is level) on a flat surface for example.

Thanks.

  Edit : I don't think this as a duplicate of my other question, this
  question focuses on one thing, the accelerometer outputs are designed
  considering g = + 9.8 m/s^2 or - 9.8 m/s^2.


texts: Multiple output flyback converter simulation in Advanced Design System

texts:
I am trying to simulate with Advanced Design System (ADS) a multiple output (one primary winding, three secondary windings) flyback converter (see the image).

But I cannot find a component in ADS library to do that...

I also tried to replace the transformer with four inductances mutually coupled (with three "mutual inductance" component). The problem is that the "mutual inductance" component from ADS library requires two parameters: the coupling coefficient k (from 0 to 1) and the mutual inductance M (expressed in Henry). How can I translate the turns ratio (n=N2/N1) of the transformer into the mutual inductance M for the coupled inductors?

Thanks in advance!

Giorgio


texts:
I'm having troubles understanding the following plot:

Where z_0 = 0 and z_\infty = 0 are the zero points and z = +i0.5; z = -i0.5 are the poles.

I know that this would be interpreted as stable it the poles would be on the left side/their real value was negative. Since their real part is zero I am not sure if this system is stable or not.

Another thing I don't understand is when this system is supposed to be causal. The unit circle is inside the ROC (shaded area) so does this mean it is causal?


texts:
I was wondering if I could use something like microcontroller instead of an ESC. I tried finding tutorials on Google and YouTube and I couldn't find anything useful. Could you please help me?

P.S.
I am planning to use this brushless motor: http://www.hobbypartz.com/88e-df40314-adf40-200-8600kv.html


texts: I've just started the electrical installation part of my engineering course and I'm clueless on how to solve this any help would be appreciated.


texts:
I'm a bit of a newbie to electrical work much more than Arduinos so I apologise if there's any inconsistency in what I'm asking!

I have a little electric vehicle project on going, a go-kart, I'm hoping to use electric motor with a built in controller that's rated for 48v at 30amps. It has over voltage protection built in and won't work if there's over 60v at the input.

The battery that I'm attempting to use to power it is composed of 18650 cells in a 16S8P arrangement which when fully charged outputs about 67.2V.  And by now I presume you can work out the problem!

Is there any reliable way to step that 67v down to around the 48v mark at 30 amps? I've looked online for suitable buck converters and they either can't handle the voltage or they can't handle the amps. Can the ones I've found that handle one or the other be run in series or parallel potentially?

Many thanks!


texts:
Does anyone have a map of the test points on the BBC micro:bit?

Specifically, I'd like to connect a scope to the lines from the nRF51's UART to the USB chip, which the published schematic suggests are connected to two test points.  Among other things, that will enable us to measure the inter-character delay caused by interrupt handling vs polling and simultanously see the output on a host computer.

I'm not reluctant to probe around myself, but I'd rather save some time ...


texts:
I am currently looking in various Arduino.

I'd like to build a very specific device:

I'd like to have a lamp (using a RGB LED (already have one)) that can change the color (or do custom routines like blinking etc...).

But these specifications must be met:

Battery powered (so all items must use minimum power)
WiFi enabled

It's sufficient if I can change the color (or trigger a routine) from a computer on the same network (via netcat or curl).

I looked in the WiFly shield. Is there another shield which is maybe better?
What main Arduino main board is best for my purpose?

Update:

As there are some follow up questions:

The Arduino is not a must. I thought it would be the easiest solution. The raspberry pi didn't come to mind, but is an excellent suggestion. However I'm not sure if it is that easy to hook an LED on to it, also I'm not sure about the Power supply (given that I would be using an USB Wifi Dongle).
I didn't think that the power supply would that big of a deal as the LED would rarely been switched on (once every few days). Is the idling in the WiFi so power intense?
For the background of what I'm trying to build: I want to build an extreme feedback device (a device to indicate the status of the automated tests in a software project) to carry around.


texts: BJT Transistor Simulation at Multisim: Why is Ie not equal to Ib+Ic?

texts:
I used current probes and Single Frequency AC Analysis (where Frequency = Frequency of the AC Voltage Source), but the Ie, Ib, Ic show that Ie is not equal to Ib + Ic?
Hope someone can clarify :)


texts:
I have a question about the safety (to the ICs) of wiring the output of one IC directly to the input of another IC.

simulate this circuit – Schematic created using CircuitLab

For instance, in the above simple circuit we wire the output of IC1 (\$Q_{1,2}\$) to the input of IC2 (\$I_{1,2}\$). My understanding is that the gates inside the IC act as a buffer such that if the gate is active it acts as a voltage source at \$V_{CC}\$ volts, however, in this case, the connection between the output of one IC and the input of the other has approximately \$0\,\Omega\$ resistance and therefore will drastically exceed the current rating of the ICs.

Is this actually a safe way to wire up ICs or is a current-limiting resistor required, and in each case, why is this the case?


texts: Suppose two 16bits numbers are added in 8085, then there is a carry, so, how do I save the carry into a memory location?


texts:
I know that electric field doesn't really flow, so whenever I'm trying to imagine electric flux like an amount of water passing through a window intuitively, I can't relate these two things.
Can somebody out there give me a more precise intuitive feeling other than the rain analogy so that I can develop a better feel for electric flux? (I'm comfortable with the intuitive feeling of electric field.)
PS: This may not be a hardcore engineering topic, so if the moderators thinks so please redirect this to the appropriate section (in that case pardon for posting here.)


texts: Converting an analog controller into a digital controller... Theory

texts: I have created a stable PI s domain controller for my system. When I go to digitize it in PSIM by adding a ZOH and a delay block and by converting the PI controller into the z domain using backward Euler, the system obviously does not behave as expected. My question is how can I redesign this controller without using software. In essence what am I trying to correct in my new digital controller and how can I calculate it on paper?


texts: How can voltage be zero when current is non zero? (Single phase series circuits)

texts:
We were taught about single phase series circuits today and I had a bit of a problem understand this little thing. Let's look at this case

1) purely capacitive circuit

It's said that current leads the voltage by an angle of 90°. So at t= 0 voltage is zero, but current is non zero. I cannot imagine this happening - it's wierd.

2) purely inductive circuit

Voltage leads the current by an angle of 90°, so there's a small period of time where there's no current inspite of a potential difference. And the current comes up only when the voltage is at wt = 90°. Again, I wonder how this is possible.


texts: I m newbie.I don't want to ruin my board.I searched and found crysal soldering to launchpad.But there is msp430 launchpad pins too.Can I solder pins directly or should I use male header or female header.I said that pins like 1.6 1.7..... Can i solder them directly


texts: On a single-layer board with no through-hole and no machine placed components, is there any need for fiducials (for example to route the board outline)? Board house has asked for permission to add fiducials to gerbers. Of course I will say yes, but I am surprised. I definitely don't need the fiducials for assembly. But the vendor seems to be saying that the fiducials will assist in cutting the board outline.


texts: High-voltage (HV) messing with my transimpedance amplifier circuit

texts:
I have a transimpedance amplifier circuit that takes 100kHz small current and gives the voltage output proportional to current amplitude. Everything works properly when nearby HV circuit is off. When it is on, the amplifier gives changing and sometimes weird results. I enclosed both in ungrounded metal boxes (should I ground the metal box around the HV?), but still problems arise. What else I should do? My circuit is on a board and wires are long, also they are not soldered (just test board). I know for RF, one should use short wires, do I also need coaxial wires between?

Overall if anyone has a good guide how to work out circuit boards with HV and RF around, please let me know.

Thanks!


texts:
I am designing a circuit to protect CMOS inputs from over voltage by using below circuit.

However, if the overvoltage is applied at Vin, the output of the LDO rises accordingly.
I designed circuit using LM3480 regulator. and Vin was 24V, with resistor = 1Kohm, that gives LDO sinking current of 19mA if it were to maintain 5V rated output voltage. The back to back diode i used is BAT54SLT1G schottkey barrier diode.

I looked at the datasheet, and in nowhere i can find such parameter that describes output sink current.

Am I supposed to look at other types of regulator such as shunt or switching?


texts: Behaviour defined in eagle when naming a gate like an orientation

texts:
I'm pondering about a possibly undefined behaviour in eagle.

Let's say you have a device named testdevice containing a gate named R90.

If you call

ADD testdevice td$1 R90 (1 1);

what will happen?

will the first gate with addlevel next or must be placed rotated by 90°?
or will the gate R90 be placed without rotation?

If you have a device having two gates R90 and R180 and you issue

ADD testdevice td$2 R90 R180 (1 1);

will it place

R90 with 180° rotation or
R180 with 90° rotation.

When thinking about this problem I see it is a very stupid idea naming gates like possible other parameters, but nevertheless it would be interesting how to formulate a consistent description of eagle's behaviour.


texts: Real rise time with oscilloscope and probe

texts:
I'm still a bit new to this domain, just wondering if the rise time of a probe and the oscilloscope itself have to be substracted to the measure in order to recover the real measured rise time?

Let's suppose a case:

My signal have a real rise time of 0.7ns.
The probe is announced to have a rise time of 1.4ns and 1.8ns for the oscilloscope.

Is the final readed value will be 1.4 + 1.8 + 0.7 = 3.9ns?


texts: Question about storing magnetic parts (DC motors and speakers)

texts:
I always have a problem with storing magnetic parts, namely DC motors and speakers, because I am afraid if I let them attach together their magnets could interact and weaken/damage each other.
So I try to put them a reasonable distance apart so they don't attach together but it's becoming a real hassle as their number increases.
I wanted to know if there's any problem with just sticking them all together (they'll literally stick together because they're magnetic) and putting them in a box.


texts:
I asked before, but I wasn't clear and after helpful answers and requesting more descriptions I explained more but nobody answered back. I don't understand electronics very well, so very sorry for my bad definitions for my previous question and for this question.

My problem is I'm going to make a project that has a motor driving a cam mechanism. The cam mechanism inertia moment is 0,001232 kg m2 and I want to rotate the motor between 0° and 160° clockwise and anticlockwise not full 360°. I want to rotate in 10° steps per 0,003125 Sec. I can rotate 70°, 80°, 90° degree or only 10° or 160°. if it is wanted 160° it will take 0,003125 X 16 = 0,05 s.
If it is 20° duration is 0,00312 X 2 = 0,00624 and motor stops immediately.

So what is my motor torque, speed or kW? What kind of a motor should I use?
Thanks for your any help in advance.


texts: Ghost? voltage on lamp outlet when turned off (72V/50V)

texts:
I have a < 10 year old house. And today I wanted to use the 2nd lamp outlet in the living room, and even though it was turned off, I got hit by electricity. I am in 230V, 50Hz country (Measured 227V). Measuring, I can see that I had 72V AC when the other lamp outlet (should be independent) was on, 50V AC when it was off. When I disconnect the mains wire for all my home TV/Stereo etc, the 50V goes up to 55V.

The voltage from the phase was measured both to Neutral and to GND. It is supposed to be air gapped when off according to all electricians I ask. And if it was connected, it should have 230V.

The other lamp outlet and this one, both have correspondance switches (i.e. turn on/off on either side of the wall). So their wires do run parallel for like 7 meters after the on/off switch. The probably shares the same phase.

I have received a 2 theories, one is the voltage is generated by electromagnetic induction.

The other that Switch mode PSUs are sending spikes out on Neutral through capacitors, that might be out of phase and frequency, such that the Neutral is where the power is. This sounds unlikely as there is around 1.2V AC between GND and Neutral.

I can say that I have switch mode PSUs on my wiring. And I have been told even my LED bulbs do have switch mode PSU.

Since a turned off lamp outlet, by all legal designs of correspondance of switches I have seen, should be air-gapped to the phase, I see no explanation where this ghost voltage is coming from.

I do consider shorting it to N so see if a fuse will be triggered (13A fuses). My electrician witht he switch mode PSU theory expects no fuse will blow.

Can I create a poor mans oscilloscope with an Arduino, a 47MOhm + 1 MOhm voltage divider and connect N to 0 and the divided voltage to A/D pin ? Use bluetooth module for data-connection to PC. Hoping to see irregularities/spikes in voltage to explain things - Supposedly I can get up to 3000 samples/sec, which should be more than sufficient for 50Hz. Should I use battery power, or just a 5V PSU ? The PSU probably uses the same Neutral anyway ?


texts:
What is the Q-factor when doing Pi-matching?

There appears to be multiple Q factor formulas and I am not sure which to use.


texts: Can I create a common ground between a rectifier and USB powered microcontroller?

texts:
I am working on firmware to decode the Marklin (MM/MFX) track protocols using a PSOC 5LP micro controller.

Is it possible to create a common ground between the track ground, micro controller ground, and rectifier -ve output?

Background:

During design, the micro controller is powered over USB from a windows pc, and actively uses a UART for informational purposes. Ultimately, the micro controller will be track powered.

The Marklin train controller (Mobile Station 2) is powered from a 36VA switched mode power supply and interfaces with a track controller box. The track controller box puts out a square wave "digital signal" that both powers and provides encoded messages to the trains/switches.

The signal below is an example (clipped by the Saleae Logic Pro 16):

This Track Signal is fed into the GPIO input p5_5 on the schematic and a current limiting resistor (R1) is used keep the current within over-voltage tolerances.

The circuit below creates a common ground point between the track ground and micro controller. The MB6S bridge rectifier produces ~17VDC.

As I would like to send some signals back from the micro controller to logic powered by the rectified voltage, I would like to create a common ground point.

simulate this circuit – Schematic created using CircuitLab

Currently I measure a potential difference of 12.98V between the two ground points I have created (point A and B on the schematic), so have not connected them together.


texts: line level Mono audio input for led flasher

texts: Looking for a super simple schematic for a line level mono input for a led flasher using batteries. Such as a trigger audio tone from a "whatever" source that turns an led on when the tone begins, and then off when the tone ends.


texts:
I have a circuit specifying a fixed 9V positive regulator; NJM78L09UA  (9V 0.1mA)

The component seems to be a bit hard to get hold of. Would like to ask advice for more common alternatives. As I'm fresh on circuit design, I don't really have any overview..

Should be SMD, ideally SOT89.

Purpose: regulator for supply by either a 9V battery or wall adapter.


texts: We're testing a 110V single phase Variable Frequency Drive(VFD) connected to a single pump having randomly let's say: R= 10ohm, L= 50mH. And I am putting these numbers to fiqure out the relationship between the output frequency from the VFD and the power consumption by the pump, so if you could make a curve or giving me the equations used in here I would be thankful.


texts: I understand that sawtooth wave can be generated using a Modulo operator, but how do I generate a sawtooth wave using a sine wave in my simulation? This was more of a thought experiment.


texts: Why \$ \frac{\mu_n}{\mu_p} \$ is very high in GaAs compared to Si or Ge

texts:
Why Electron to hole mobility ratio is very high in GaAs compared to Si or Ge?
That is \$ \frac{\mu_n}{\mu_p} \$ (in GaAs) \$ =21.25 \$ whereas
\$ \frac{\mu_n}{\mu_p} \$ (in Si or Ge) \$ \in [2.1,2.6] \$ at Room Temperature

My Thoughts:
May be because GaAs is a compound semiconductor


texts: Can 74HCT buffers work just as well as 74HC buffers between parallel port and target?

texts:
I'm making a circuit to program the AT89S52 microcontroller in a serial fashion as follows:

Call me paranoid but this time I'm using resistors on all outputs to the micro as well as RC networks on the reset and clock lines. I also am using a jumper on the EA/VPP line in case I need to use it for programming as well.

I am using NOR gates (I know I know, I'm using the european version instead of the US version of the symbols but they're designed more neatly) as a latch to control all communications.

Because this design (that I made the PCB for) calls for 74HC series of chips, I happen to own a 74HCT02 NOR gate, but I don't own any 74HC02 NOR gates.

This circuit is powered with regulated 5VDC and the parallel port is set to run in Standard Parallel port mode with no bidirectional capability.

If I replaced the 74HC02 with 74HCT02, would the circuit still work without the need for any extra parts?


texts: Dual slope edge detection for a phototransistor

texts:
I want to detect sudden changes in light level using a phototransistor. The goal is to transmit information optically using the timing of the transitions, ideally using an LCD screen.

LCD transitions are typically in the range of 5-8ms for black to white, so the slew rate of the signal will be in that region too. Doing some experiments the voltage swing will probably be in the 100mV range.

The ambient light level is not fixed. This is not a controlled environment. So the system needs to automatically calibrate to the ambient level.

Current I have the following system that detects falling edges only:

The red area simulates the phototransistor getting a 60Hz on/off flash. As you can see, the circuit simply compares 98% amplitude version of the signal (1k/50k divider) with a low pass filtered version. On a falling edge the low pass filtered signal is momentarily higher than the 98% version ad the comparator pulls its output low.

I've had success with this method. It tends to be a bit fiddly and require some calibration to work well, but it does work.

I want to instead detect both the falling and rising edges. That will double the data rate. Any improvements to the auto levelling would be welcome too. Minimizing the number of components is important.

Note: I have looked at this question but none of the answers are suitable as they won't work with the small output signal from the phototransistor.


texts: Fixing a heated water dish: Pointers to a temperature table or guide for power resitors?

texts:
I'm fixing a heated water dish, used so that the dogs don't have to eat snow.  The previous dish was heated with a wire embedded in what appears to be ceramic, on a foil back on the bottom side of the dish.  This failed.  Previous experience with this company's dish (Farm Innovators) indicates that 1-2 years is a typical life span for this type of dish.

The rated power for this assembly was 60W.  It had a disk thermostat with about a 15 degree F hysterisis in series with the heating element.

It occurs to me that I could replace this heating foil with a handfull of 10 ohm, 10 W power resistors, connected in series, and glued to the bottom of the plastic bowl using thermal glue.

However, this puts the heat in a much smaller space.  It's not clear to me if this poses a fire hazard.  I'd like to find a guide that gives typical operating temperatures for a given geometry of resistor and surrounds.

In normal operation, the thermostat should be sufficient to protect the bowl and floor, however, I figure I need to design so that failure of the thermostat to open doesn't result in too high a temperature.

I would like to include a temperature sensitive fuse in the circuit.  Some that melts at, say 80 C -- well above the operating temperature, but low enough to not catch fire.

Alternate method: Use 32 guage nichrome wire (10 ohms/foot)  I would need 20 feet of this with 130v (rural power) to get approximately the same heating effect.  Invert bowl.  Glue roofing nails to bottom of basin.  Pour 1/8" plaster of paris or tile set mortar.  Allow to set.  Trim nails to 1/8 above mortar.  Wind wire from nail to nail in zigzag.  Place thermostat.  Add 2nd layer of bedding substance.

Nichrome reaction with highly basic mortar?

32 guage wire would puts a lot of heat flux through  small area.  Would the wire embedded like this overheat?


texts: Using a variable resistor with a DC motor

texts:
As you may have guessed I am not particularly adept when it comes to electronics. This is something I want to change, so I thought I would make a simple circuit that controls the rotation of an electric motor. So I purchased a POT (B203) and some DC motoros(3v) and built the circuit. This circuit works perfectly fine when replacing the motor with an LED but when I place the motor in the circuit (replacing the LED) the motor does not work.
I am guessing the POT resistance is too high in the above case, at 20k. So I thought I would try some other values. I have tried a 1K and 5K (those burnt out straight away). So before I start purchasing more POTs I thought I would ask the people that know. How can I find out which POT I need? Apologies if this is a stupid question :(.


texts: How to determine drain and source resistor values for common source JFET?

texts:
I am designing a simple common source JFET circuit as the front end to a guitar amplifier. It looks like this:

I arrived at the RD and RS values experimentally. I would prefer to determine them using a formula or graphical method, but I have had no luck finding anything.
I understand the drain resistor's role in determining gain. I understand how the source resistor works in self-biasing and its negative effect on gain. I understand how the voltage divider at the gate helps make the operating point more stable across manufacturing variations in JFETs. What I don't fully understand is the selection of the drain resistor and its relation to the source resistor. All of the references and instructional material I've found seem to start with "Given Rd is X and Rs is Y..." as if these values were passed down on stone tablets never to be questioned.
I am working with a Fairchild J112, with an IDSS of 5mA and a Vgs(off) of between -1V and -5V. I selected my source and drain resistors using a combination of conceptual analysis and experimentation.
This was my thought process:

IDSS is the max current when gate voltage is zero. I plotted a load line with a Y-intercept of 5mA (IDSS) and an X-intercept of 12V (my supply voltage.)
I chose an operating point in the middle (6 volts, 2.5mA)
I used Ohm's law to determine a total resistance of 4.8k Ohms would give me 5mA at 12V. The internal "on resistance" of the J112 is low, listed at 50 Ohms, so I did not bother factoring it into the calculation.
I experimented with various drain and source resistor combinations that added up to around 4.8k.
For each combination, I measured the voltages across the drain and source resistors with a goal of the DC output (at the drain terminal) being in the center of the supply voltage while still maintaining the correct bias.

I settled on 3.3k and 2.2k (higher, but standard values) for the drain and source resistors, respectively. This gives me an output voltage of just under 6V (half my supply voltage.) I plan to bypass the source resistor to maximize gain.
My question is: Is there a better way to do this? Is there a graphical method or set of formulas that determines the values of drain and source resistors for a given design? Am I close to the mark with the method I used?


texts: Will leaving 1 of the 3 GND pins on the ATMEGA328p ungrounded cause any problems?

texts: I am creating a circuit using an ATMEGA328P and i am unable to ground one of the 3 ground pins (other 2 are fine) due to limitations of my design. I have tested the IC with a multimeter and the pin does seem to be connected to the other ground pins which makes me think that it should be ok if it is left out. is there any problem with me doing this? thanks.


texts: Microprocessor controlling SRAM through an FPGA

texts:
I have an ARM Cortex 3M (reference manual here) connected through the FSMC (Flexible Static Memory Controller) to a Spartan 6 FPGA. In turn, the Spartan 6 is connected to some external SRAM.

I need to production test the SRAM. As I see it, I have two options:

Write an SRAM driver directly from the FPGA (without involving the Cortex).
Route the Cortex memory pins through the FPGA to the memory.

Reading through the specs of the SRAM, it seems that writing an SRAM driver for the FPGA is a relatively difficult task. I am therefore inclined to go with option 2. However, I was told that there may be latency issues if I naively bridge up the Cortex to the SRAM.

How can I deal with those potential latency issues? Are there other difficulties arising from option 2 that I might be overlooking?


texts: Electromagnetic EM waves - How they coexist in same space and time without signal impact?

texts:
I'm having difficulty understanding how 2 EM waves from 2 sources can co exist in same space and time, without changing one another from a Quantum Electrodynamics Perspective.

If a charged source emits photons which excite electrons in Field Region X.... then how can another wave from a different source not impact the first EM wave due to an increase in Electron Excitation on ((same)) electrons in same Field Region X in same time.

I didn't think different electrons were excited by different wave sources... otherwise, how can Electron State = Wave1 .... when another Force from Wave2 is exerted on it?


texts: LED Matrix Constant Current Driver with MOSFET and NPN Trans

texts:
I draw the circuit for driving Strings of LEDs. I have regulated DC supply of 17.5V @ 1A. I didn't choose constant current supply because it was adding extra cost to the whole project, therefore for driving LEDs I am using Constant Current source driver based on N channel MOSFET and NPN Transistor with some resistors, it's cheap and cost effective solution, as I have to keep the cost of project as low as possible.

I visited many website and tutorials for how it works and have this circuit made, I am still not sure about the circuit :-

Here is the Circuit to Drive 20 LEDs using ESP8266 SoC Module.

Component Specifications :-

White LED(SMD) - Package 2835

Vf = 3.1-3.2V
If = 60mA(Typ), 90mA(Max), Pulse current = (150mA)

Q1 (N-channel MOSFET) - Package SOT-23

IDS: 5.8A
VGS: ±12V
VDS: 30V
VGS(th) = 1.05V
RDS(ON) (at VGS=10V)    < 28mΩ
RDS(ON) (at VGS = 4.5V) < 33mΩ
RDS(ON) (at VGS = 2.5V) < 52mΩ

Some Other info :-

Link to Datasheet :- http://www.aosmd.com/pdfs/datasheet/ao3400.pdf

MMBT3904 NPN Transistor

Link to Datasheet :- http://www.onsemi.com/pub/Collateral/MMBT3904LT1-D.PDF

Some Calculations :-

The Needed Current to fully glow all 5Series 4Parallel LEDs = 360mA (90*4).
Total voltage drop across LEDs = 16V (3.2*5).
Input Voltage = 17.5V @ 1A
The Vbe of NPN = 0.7V

The Current though MOSFET and LED will be defined by R5 and R6 resistors.
Therefore

  R5 = R6  = 0.7/If(LED)
  R5 = R6  = 0.7/0.45 ohm.  (450 mA taken, extra 100 mA as buffer)
  R5 = R6  = 1.5 ohm

Power Dissipation at R5 and R6 :-

Ps = 0.49/1.5 W
Ps = 326 mW

Voltage Drop Across MOSFET:-

Vm = Vs - Vf(LED) - Vbe
Vm = 17.5 - 16 - 0.7
Vm = 0.8 V

Power Dissipation on the MOSFET :-

Pm = Vm * If (LED)
Pm = 0.8 * 0.45
Pm = 360 mW

Reference PCB board with Aluminium Heatsink on the backside :-

Questions :-

Is circuit appropriate to drive all 20 Leds with above calculations?
Any thermal run away issue with the circuit?
Do I need limiting resistance on the LED side?
What does Pulse current refer to in LEDs?
What is the use of Resistance R21 & R7 in circuit?

Edit :-

The Vf vs Junction temperature Graph :-

The Vf vs If Graph :-


texts: Movement of electron direction in ac current is continuously changing which leads to more collision of electrons then dc current.From this can we conclude that ac current heated the wire more than dc current having same magnitude?


texts: Flux protection vs. sealed relay enclosures

texts:
When reading the datasheet for the Omron G5Q series relays, there are two options for enclosures: flux protection and sealed.

The price difference is almost a factor of two, with the former being the more expensive.  Is there an application where flux protection is required, or where a sealed enclosure would suffice?


texts: Battery indication on extremely simple 9V circuit

texts:
I have constructed a slug fence around my asparagus planting beds. Its a very simple circuit, 2 stainless wires 10mm apart going around the perimeter of the fence in a circle. Each circle is connected to a wire that ends up inside a silicone sealed plastic container with a 9V battery holder inside.

Slug crosses one wire, nothing happens.
Slug crosses both wires, closes the circuit and gets a buzz.

9v doesnt really harm them but is enough for them to turn around and go somewhere else.

My problem is that I have no good way of knowing if the battery is charged or not. One night with no charge and my plants will get butchered.

I had an idea to put a LED on the circuit so I can close the circuit with my fingers and see if it lights up. What would that require? Are there any low power 9V LEDs or do I have to put a resistor somewhere? Wouldn't this resistor affect the current going through the slugs?

Happy for any suggestions!


texts: How to create a state transition table for a Mealy machine

texts:
I'm trying to design the counter shown in the diagram below with the counting sequence 123456 (i.e X1=1, X2=2, ...) as a Mealy machine.

However, I'm having trouble figuring out how to create the state transition table for the machine. For context, I designed this counter as a Moore machine using 3 D flip flops, and I implemented it on a FPGA board. When I push a button on the board (Rb), the number is displayed. I guess what I'm struggling with is how the table for the Mealy machine would differ from that of the Moore machine. For example, the first two rows of my Moore table look like this:

How does the input affect the output any differently than the Moore machine? (Apologies for the long question)


texts: ERC for power pin drive - Altium Designer

texts:
It'd be of great use for us to emit correct rule check violations for power pins in IC we use.
The logic is to force compiling failure when power pins of ICs are not driven correctly from power sources.

When we used KiCad Power pin could have been in or out hence when PowerIn pins where not connected to PowerOut pin an ERC error was emitted, but with Altium designer we only have Power Pin without direction.

The only violation on the matter is when input pins are not driven by output or power pin.

The only workaround we thought of is changing our ICs power pin to input pins, but we would really like to avoid that.

Are we missing something?

P.S. The hypothesis is of course that the violations are correctly signalled through project preferences in connection matrix and in error reporting tabs


texts: Can batteries shrink physically in size?

texts: A few days ago I took apart my laptop,an HP BC000nq, with the intention of adding a new 4GB RAM module but I found something intriguing.The battery surface was carved with deep cavities between each cell.At first glance it seems like the battery wrap shrunk against each of the cells body,the battery seems alright it even holds charges.Is this even possible? Should I be worried?


texts: Meaning of "no exposed metal in this area" on connector drawing

texts:
I am looking at the mechanical drawing for the JAE WP7B-P050VA1 connector, and it has the following drawing suggesting a PCB footprint:

My question pertains to the "no exposed metal in this area" note: does this mean that I am not allowed to run any traces through this area, or is doing so fine as long as it is covered by solder mask?


texts: Why not use a ferrite bead around an RS-232 cable?

texts:
This is from the instruction manual of a printer:

As you can see, one is not supposed to wrap the supplied bead around the serial cable. What is the reason for this?


texts:
I have converted mains from 240V RMS (330V) AC @ 50Hz to 2.5V AC using a transformer and am now trying to put the wave into an ADC that operates at 0-5V.

I am looking to convert a 1.76V RMS (2.5V) AC @ 50Hz (5V pp) sin wave into a 5V DC sin wave (5V pp), i know i require an op amp although i'm pulling blanks from my mind. Thanks for all the help. The reason is is i need to input the wave into an ADC that operated between 0-5V.

At this point i guess i need a summing amplifier that acts as a DC level control.


texts: Is thermoelectric cooler needed to produce constant laser output?

texts: I'm making a laser diode module using a LD, a PD, and a LD driver board. With the components I would be able to monitor the optical output from the LD and then adjust current to keep the output constant. However, I wonder if I also need a TEC. The ambient temperature of my device would change fast (1℃/1min). Wouldn't it be enough to adjust the power using the PD and a LD driver IC? The temperature would not exceed the operating temperature range.


texts:
I need help deciphering a BOM that comes with a particular TI reference design. If you look at "Partlist.rep" in the zip file, it looks something like this [I've edited it down a bit]:

R1          Resistor 0402                 R_270_0402_F
R2          Resistor 0402                 R_2_0402_F
R4          Resistor 0402                 R_4K7_0402_G
R8          Resistor, 0402                R_0_0402
L235        Inductor 0402                 L_12N_0402_J
L236        Inductor 0402                 L_1N8_0402_S
C1          Capacitor 0603                C_1U_0603_X5R_L_6P3
C2          Capacitor 0603                C_4U7_0603_X5R_K_6
C4          Capacitor, 0402               C_47P_0402_NP0_J_50
C121        Capacitor 0402                C_100N_0402_X5R_K_10
C191        Capacitor 0402                C_10N_0402_X7R_K_25
C214        Capacitor 0402                C_22P_0402_NP0_J_50
C231        Capacitor 0402                C_1P0_0402_NP0_C_50
C261        Capacitor 0402                C_220P_0402_NP0_J_50
C291        Capacitor 0402                C_100N_0402_X5R_K_10
C301        Capacitor 0402                C_1U_0402_X5R_K_6P3

I have some questions about interpreting part names:

Resistors: "R_270_0402_F" is a 270 Ohm resistor, 0402 package. But what does the 'F' signify? How about 'G', or the lack of a letter at all?  Do these have something to do with tolerances, or type (thick film, thin film, etc.) ?
Inductors: "L_1N8_0402_S" is a 1.8 nH inductor in an 0402 package. What does the 'S' indicate?  Or the 'J' ?
Capacitors: "C_1U_0402_X5R_K_6P3" is a 1 μF capacitor in an 0402 package. "X5R" ("X7R", "NP0") refers to the type/temperature characteristic. The following are educated guesses from reading datasheets: 'K' refers to capacitance tolerance: K = +/-10%, J = +/-5%, C = +/-0.25pF. Am I correct, and what about 'L'? The final number must refer to rated voltage, (10 = 10V, 25 = 25V, etc.) I assume "6P3" mean 6.3V.

Thanks for your help.


texts: Why do I need to make an intermediate step on switching a pin from input to output On Atmega328p microcontroller?

texts:
On the Atmega328p datasheet p.99 The following was mentioned.

Switching Between Input and Output:

When switching between tri-state ({DDxn, PORTxn} = 0b00) and output high ({DDxn, PORTxn} = 0b11),
an intermediate state with either pull-up enabled {DDxn, PORTxn} = 0b01) or output low ({DDxn, PORTxn} = 0b10) must occur. Normally, the pull-up enabled state is fully acceptable, as a high-impedance environment will not notice the difference between a strong high driver and a pull-up. If this is not the case, the PUD bit in the MCUCR Register can be set to disable all pull-ups in all ports.
Switching between input with pull-up and output low generates the same problem. The user must use either the tri-state ({DDxn, PORTxn} = 0b00) or the output high state ({DDxn, PORTxn} = 0b11) as an intermediate step.

Why Do I need such an intermediate step in the first place?


texts: Java/Arduino Controlled 120VAC Power Outlet

texts:
I'm working on a project with an end goal of controlling a power outlet with a Java program.  Currently, I have the relay wired to outlets, a 3 prong 120 VAC plug, and my Arduino.  Everything works as intended: my Java program can trigger the relay/outlets on and off.

The problem:

When I have a load hooked up to the controlled outlets, my Java program will crash after a few cycles of on/off (changes depending on the load plugged in).  If I unplug all loads from the outlet- it cycles on/off seemingly forever.  How do I change my system so that Java will not crash, irregardless of load?  What is causing a difference in the Arduino from a load being connected?

My attempts:

I have tried using an external power source to power the relay and
only using the Arduino to pull pins to a common ground.  Same result.
I have tried to debug my Java program extensively.  The error occurs
trying to write data to the serial port.  Keep in mind, however, the
program will successfully write data a couple times (number depending
on the load) before it fails.
I have tried all outlets (both relays) and have had the same results
on all.

Additional Information:

A 12 W rated alarm clock causes the error much quicker than a 14 W
rated hot glue gun.
Both outlets are GFCIs.

Please let me know if there is any other information that would help solve this problem.

Edit 1:  Just realized that I don't have true optical isolation (that I thought I had) because the jumper was left on Vcc and JD-Vcc.  I will try later this evening with and external power source to control the coil (JD-Vcc) and the Arduino to control the 'switches' (Vcc).  Will report back to share results.

Edit 2: Pulling the coupler and feeding JD-Vcc from a separate power supply (common ground) did not work.  I've put 330 Ohm resistors between Arduino pins and relays; didn't solve the problem (might have given me more on/off cycles before failure, but not a fix).  Switched the wiring so the outlet is normally off (was my intended configuration).  Working on a wiring diagram, brb.

Edit 3: Circuit Diagram. Yes, its ugly.  The switches on the Sain Smart are closed when IN1/IN2 are pulled low.  And now I see there is a built in schematic function here.  Good to know for next time.

Edit 4: I haven't managed to figure out why it is acting like this.  Anyone have any ideas?  At this point, a work-around may be acceptable.  Capacitors, resistors, opto-couplers?  What would be best/cheapest?

Edit 5: Would a snubber (Red Lion, SNUB0000) across each outlet be of any benefit?  I finally found a related post (#101815, I can't add another link) but am not sure if I can apply any of the potential solutions.  Its been recommended putting a small ceramic capacity across the Vin of the Arduino; is putting it between the 5V arduino pin and ground what was meant by this?


texts: How to design analogue compensation for SMPS from Bode Plots?

texts:
In a complicated switched mode power supply where the transfer function is unknown, is there a way to design an analogue controller and compensation from the bode plot alone? I am having difficulty understanding how to calculate the poles and zeros of my system, and therefore difficulty in where to place the compensator poles and zeros.

I am able to use LTSpice to get the Bode plot of my system with a CLC pi-filter attached to reduce the voltage ripple on the output. I will attach this.

I gave no thought into the control loop as I was designing my power supply - the bode plot looks very strange to me and I have absolutely no clue how to interpret this to allow me to decide where to place the compensator poles and zeros to counteract the effects of the SMPS and ensure it is stable to transient load changes.

Furthermore, is there a way to decide whether I need a lag or a lead compensator?

Any help appreciated, thanks.


texts: Explanation of an electric motor schematic

texts:
Below is the schematic of a Bosch electric motor:

What are the three double-lined (one thick one thin) elements on the left side?
What is the part on the right (black thick lines)?
What is the white circle and black triangle exiting the motor on the right?

The complete manual with some symbol explanations is given here on page 6:


texts: Minimize current consulption for MIDI input circuit?

texts:
I'm using a MIDI input circuit like the one shown in the schematic below. R1 is not touched as driven by the input device. R2 is fed from my internal power supply. The device is very low power so I would like to minimize current consumption as much as possible. I did notice that when having a 220 Ohm resistor the current consumption of the circuit went up. I swapped it for a 5k Ohm resistor and now it's better, however I am wondering how low can I go safely?

The datasheet has a table in it on page 2, however I'm not sure I understand it correctly. The junction of R2 and 6N138's pin 6 go into an MCU's UART module with an input resistance of about 5k Ohm.


texts: Speed and position controle of a BLDC motor at the same time

texts:
I want to know if it is physically possible for a BLDC motor to be controlled in speed and position at the same time.

Let me clarify : while the rotor is spinning (speed control), is it possible to rotate the stator backward or forward (position control).

I don't know if I made myself clear enough...


texts: How to determine if level shifting is necessary between a 1.8V device (ICM-20948) and a 3.3V device (Arduino Nano 33 BLE)?

texts:
Background
I'm having trouble determining the requirements for interfacing between the ICM-20948 and the Arduino Nano 33 BLE. The biggest issue for me is that there is a detailed datasheet on the nRF52840 that the Nano uses, but not the not the nano itself.
The ICM-20948 can operate with a VDD of 3.3V like the Nano, but the VDDIO is about 1.8V for the ICM-20948.
For transmitting data to the ICM
The ICM datasheet states that the maximum logical LOW voltage is 0.3*VDDIO (=0.54V) and the datasheet for the nRF52840 states that the max output voltage for LOW logic output is VSS+0.4 (=0.4V). Is this too close considering component thresholds? (I also can't find the max voltage tolerances for these IMU IO pins in the datasheet, so I don't know if they could handle the 3.3V logic from the Nano)
For transmitting data from the ICM
ICM has a min HIGH level output voltage of 0.9*VDDIO (1.62V) and the datasheet for the nRF52840 states that the min input voltage for logical HIGH is 0.7V*VDD (2.31V). So I would definitely need some sort of level shifting for transmitting from the ICM to the Nano, right?
For the level shifting, could I just use resistors or would I need (or would it be more practical) to use dedicated level shifters?


texts: PI Controller Design (Ziegler-Nichols) and Unit Step Response Graphing for 4th order system

texts:
I have a system that requires a PI controller designed using the Ziegler-Nichols Methods. I would also like to plot the unit step response in Matlab, but I am getting extremely weird results.

This is what the system looks like:
$$G(s)=\frac{32}{(s+2)^4}$$

I plotted the curve in Matlab and printed the graph out to use the FOPDT approximant graphically. I know it is probably possible to do it using Matlab, but I come from a mathematics background and would rather use graphical methods.

Finding the quantities is trivial, and this is my result:
$$F(s)=\frac{2}{2.519s+1}e^{-0.441s}$$
I put my graphical parameters and tuned it in Matlab. Could have done the approximation by inspection, this however should help for greater understanding. Anyway, these are the parameters:
$$K_0=2$$
$$L=0.441$$
$$t=2.5188$$

Then using Ziegler-Nichol's table for tuning, I obtained the following PI controller:
$$C(s)=5.1451\left(1+\frac{1}{1.4687s}\right)=\frac{7.557 s + 5.145}{1.469s}$$

I would now like to plot the closed loop step response, which should look like an unstable underdamped system that eventually stabilises. The system should oscillate drastically, such as:

This is what I get instead:

Which is totally wrong.

Here's the (relevant) matlab code:

%Unknown Transfer function

s=tf('s');

Gr=32/(s+2)^4;

% step(Gr)

% Approximation Taylor

K0=2; %Numerator gain factor

L=.4406; %Exponent power gain factor

t=2.5188; %Denominator gain factor

Go=(K0*exp(-L.*s)).*((t*s+1)^(-1));

%PI

Ti=L/.3;

Td=0;

Kp=.9*t/L; %gain

% Ki=Kp/Ti;

% Kd=Td*Kp;

Cpi=Kp*(1+1/(Ti*s));

Css=5.1451*(1+1/(1.4687*s));

%Closed Loop, Real

Gs=feedback(Gr*Css,1);

step(Gs)

(Feel free to edit this messy code list into something more tolerable)

I think my code is wrong somehow, I just don't understand how that result make sense.

The code is basically creating the 2 blocks, and then plotting for closed loop via the feedback command, unity feedback configuration.

Any tips and help is appreciated.
Thanks.

Edit: Nichols-Ziegler Table and information


texts: Negative feedback- noninverting voltage amplifier

texts:
It is negative feedback that provides the almost zero voltage across the input terminals
of an op amp, but how to understand this with noninverting voltage amplifier maintaining zero voltage across the input terminals (what feedback does)?


texts: harvested a joystick from a fight con, want to use it to take input into an arduino. how do I wire up the switches?

texts:
the joystick is just 4 switches around a shaft (up, down, left, right)- 0, 1, or 2 of them are engaged depending on direction the joystick is being pulled.

here are some images showing what I'm talking about: http://forums.shoryuken.com/discussion/196736/korean-arcade-parts-discussion/p2

I came across that site by searching the (id?) number on the switches: AM51630C69N

The full info I'm able to get from reading the switch itself is this:

AM51630C69N
121011E
16A250VAC
Thailand

(This comes up when I search for AM51630C69N schematic, though it seems this doesn't have the same number, and is made by panasonic, which I don't think my switches are (they have a [M] logo on them) http://uk.rs-online.com/web/p/microswitches/5224330/ )

I'm not an electrical engineer, so I'm a bit lost. One thing I noticed is they all share the "pull" pin (er, they're all connected anyways), with a black wire (ground?). and they only have one "throw" pin each.

So, how should I wire this up to take input?

Other questions: what does 16 amps / 250 volts have to do with anything? If I'm connecting to ground + input, where am I putting the voltage? Also- those are waaay higher than anything an arduino can output... does that mean I'm out of luck?

I vaguely remember seeing a problem like this years ago- is the way this gets hooked up something like as follows:

Hook ground to ground. Hook input to an input pin on the arduino. Also, hook that input pin to voltage(?), then you'll read 1 when the switch isn't triggered, and 0 when it is (it will pull the voltage directly to ground when ground is connected?)

Any help/direction would be appreciated!


texts: I am making a small project for myself but have very limited knowledge on electrical engineering (V=IR is about all i know). I want to power nine LEDs (max 28 mA, 2.25V) with one battery. Do i connect them in series or in parallel? What voltage battery should i use? do i need a resistor? I have no clue how to wire this all up and with what components, but im sure some of you electrical engineers could help.


texts: Parallel Diode with AC voltage and DC voltage

texts:
Hello, I have some question about the circuit i posted as photo file.
I have there a AC source 4V amplitude. R= 100k ohm. Uv=1.5v. RB=680k ohm.
I know that diode flows current at one direction. And when u have AC source you have either a only positive voltage through a diode or a only a negetive voltage.
But I dont understand the circuit when you have a DC source of 1.5V for first part and then 4.5 V for second part.

I did the simulation of the two parts: The green one is AC signal and the blue one is de voltage through de Resistor 680K ohm. But I dont understand the working of this circuit? Can someone please explain me this circuit.


texts: How to switch power supply between two 24V batteries automatically & efficiently

texts:
Currently, I have a circuit with two motors (200 W, 24V, 8A max), motor drivers, DC DC converters, controllers and other components powered by a 24V Li-ion battery. The problem with current setup is whenever the battery drains, we need to replace it with the fully charged battery which forces us to shut down the whole system while swapping batteries.

The proposed idea for this issue is to use two batteries and design a power management system such that if one battery drains below the threshold voltage, the circuit automatically switches power supply to the other battery and vise versa. Before the second battery depletes, the user will be prompted to replace the first battery and vice versa. The battery management circuit should also measure the voltage level via Arduino Analog pins so that user can be prompted.

Though, i found many useful information from similar posts, i am still feeling little bit lost.

How to use diode oring to switch between two power sources

From the above link, i found 2 simple circuits.

The main problem with the circuit above is that if we use batteries for both sources (V1 and V2) , they deplete concurrently which is not preferred in my case.

In the circuit above, When V1 is cut off or drops below threshold voltage, the relay switches two V2. But, the problem is once V1 is connected back, the circuit switches back from V2 to V1 which again is not desired.

What I am looking for is a solution where the circuit runs on first battery and when the first battery drops below the threshold value, the circuit should switch to second battery and the user will later replace the first battery. Again, when the second battery voltage drops below the threshold value, the circuit should switch back to the first battery. This is to ensure that the battery is fully drained before charging.

I am open to use diodes, relays, transistors and arduino (it's already in the circuit). I am afraid there might by huge power loss if we use diodes.

Please, feel free to advise and comment :)


texts:
I searched for parts on line for IF application for use with configuration shown below. The transformer is tunable by screwing the core in and out of transformer housing.

However, the transformer turn ratio is asymmetric as shown above in red number.
Intuitively, I think the turn ratio on the primary side should be symmetrical since the circuit around it is symmetrical.

Will above circuit function fine even if the turn ratios are not symmetric?

What are the uses for such transformer?


texts: How can I obtain a PDF file from a schematic in Orcad (with .dbk extension)? Is there a converter?


texts: Is this a capacitor in series with the power source?

texts: I'm a complete newcomer here. I was looking at this small circuit and it looks like there is a capacitor connected in series with the power source. Is it possible that this is the case, or do capacitors always have to be connected in parallel with the power source?


texts: Altium selecting problem with imported DXF file

texts:
I've imported a DXF file on to my PCB editor in altium designer 18.
 The problem I have is Altium will not selcet my import. I've tried select All I've run my mouse over the object, some of the object seems to be selected but t he radius's are misssed out.
Ive tried putting all the imports on one mechanical layer still doesnt work.
This is driving me nuts can anyone help??


texts: What comparator is compatible with OPA2132?

texts:
I've designed a circuit but realized now - when the 200+ boards finally arrived - that I've made a mistake.

Long story short: I made the prototype on a breadboard, using OPA2132 (because that's what I had at home) coupled as a comparator (fixed ref at in-, signal at in+). The breadboard version somehow worked like a charm, but when sitting on the PCB the output is never brought down to GND when in- (6.5V) > in+ (1.8V). Instead, the output is around 1V, and that screws everything up.

Being a hobbyist, I cannot afford to buy new boards, so the only solution here is to find pin-compatible comparator (SO8) that does not cost a fortune, that I can replace. OPA2132 is not open-collector. Vcc for my circuit will never be over 13V, and it's single fed (no negative voltages).

How can I find a replacement IC without browsing through zillions of datasheets?

OPA2132 datasheet: http://www.ti.com/lit/pdf/SBOS054


texts: Resistor that changes resistance with clock input

texts: I am making a 555 a stable connected to a 4510 and 4511 and an led row. I need the led row to get faster and therefore the 555 astable to get faster, the more times a button is pushed. I am thinking a resistor that changes resistance with a clock input and a reset function but I am new to electronics so anything is appreciated! A video of the circuit so far is here: https:https://goo.gl/5luzl1, and data sheets for the 4510 (I can only post two links so no 4511 pinout) is here: https://goo.gl/1UMyLg. Any ideas? Thanks


texts: Checking correctness of an instruction and addressing mode

texts:
I'm given set of instructions and set of addressing modes that can used. In the first loaded byte is stored operation code of an instruction and in second byte is the addressing mode that instruction uses.
I'm supposed to check if there's an error and if there is, I should activate an insterror (instruction error) signal. Error is considered one of the following:

Wrong operation code: Loaded code is not present in the list of available instructions
Wrong addressing mode: Loaded addressing mode is not in the list of the available ones
Wrong combination of OC and mode

So, I was thinking this way:

Load first byte
Check if OC is correct  -> if not then insterror
Load second byte
Check if mode is correct -> if not then insterror
Check if OC and mode are correct -> if not then insterror

I'm not very familiar with eficient combining of logic components and I had a problem to find a way to, using one signal, test only for first byte, then only for second byte, then for their combination. So I've tried this way: since addressing mode is only given for address instructions, I've made this:

So, basically, if it's one of expected instructions and expected modes, then I'll activate adr2 signal (which is short for address instruction of 2B). Similarily I did for the rest of instructions. Then I had this:

Here, ST * immed is the only wrong combination of OC and mode here (STORE * immediate).
So here, I say, if none of the expected types of instructions are activated (bezadr1, branch2 etc.), then they'll all have value 0 which I'll invert to 1 with NOT gate, which will then activate AND gate which will activate insterror signal.
I'm currently having problems with rest of my problem, so I can't verify if this actually works, but I think the way of thinking here is okay. Now, even though this (may) work, I'm aware that this actually doesn't solve the problem in the way it's supposed to - since this only checks after 2nd byte of instruction is loaded and then basically checks possible combinations, so it's essentially doing only 3rd error check (but used in a way to check 1st and 2nd).
I think that ST*immed is how I'm supposed to check for 3rd error type. I'm thinking to use one OR gate fot "if one of error types then activate insterror", like in this pseudocode:

But I don't know what and how to use to do 1st and 2nd error check the way it's supposed to be checked. Any help appreciated.
EDIT: I store operation code in first byte of register, then a couple of clocks later in second byte of register I store addressing mode. I'm given specific instructions and mode and how they are represented using bits of those two registers, so I know what is allowed to be written in registers.
It would be easy if I could use two signals to check for error, one for op code and one for modes, but I'm only allowed to use one. Now, if I could check for errors after second byte is stored, I think my solution from above would work.
But from how the problem is formulated, I think that it's expected from me to store first byte, then check if the op code is correct, then store second byte, then check for remaining two errors.
And I don't know how to do that using only one signal because of this:
I use inverted AND gate with available op codes - if none is activated (meaning it's not on the list of available ones) inverted AND will turn it to 1 and i'll have my error signal.
I use inverted AND gate with available modes - if none is activated inverted AND will turn it to 1 and i'll have my error signal.
But both of those gates are present in checking after storing first byte. First byte is storing op code, so I'll be checking for mode as well even though I didn't even store mode yet - which will result in error.


texts:
I have this circuit that I'm trying to repair. I cannot determine where specifically the issue begins.
The bridge rectifiers are receiving AC voltage as they were good, the problem is the the voltage output from the secondary of the transformer.
As you can see under pin 9 and 8 of T6301, it is the coil that outputs 7V of a half wave power supply. Neither 9 and 8 pins has a output voltage. It is 0 ohms.
I have no idea how the transformer was built but it was proprietary from Sony.
I wonder if that is oscillating or what part is causing oscillation for the transformer to work on DC. Maybe someone can help me.


texts: USB 3: keyed connector protocol adherence necessary?

texts:
The USB 2 specification presents the concept of the "Keyed Connector Protocol" in chapter 6 section 2 (6.2). Basically, as I understand it, this limits the use of type A receptacles to downstream outputs form USB hosts or hubs. This is how it is meant to be:

+-------------------+      +----------+
|                   |      |          |
| Type A Receptacle +------> USB Host |
|                   |      |          |
+-------------------+      +----------+

I could not find the topic being picked up in any newer specification like USB 3.2. Can I build a USB device with a type A receptacle or is this not compliant? This is how I wanna use it:

+-------------------+      +----------+
|                   |      |          |
| Type A Receptacle +------> USB Dev. |
|                   |      |          |
+-------------------+      +----------+


texts: Analog Design to VLSI Layout Tool/Software

texts: I want to implement an 555 timer. I am looking for tools preferably FREE ones. I looked at certain tools which have GUI where I can select and drop transistors which I find tedious. Is there any language which I can use to describe transistors , something like a analog counterpart of VHDL/Verilog. Also the language /tool used should give me the VLSI layout.


texts: Battery voltage select and ADC measurement (OpAmp + uC)

texts:
I need to measure battery voltage which supplies my electronics.

Vbat supplies buck-boost DC/DC converter then goes to uC and other ICs (3,3V).
I want to use 3x2 goldpins in conjunction with OpAmp to select Vbat voltage range: U1 (3,6V Li-Ion) or U2 (7,2 2x Li-Ion) or U3 (12V Pb) which generate 0V to 3,3V on uC ADC input / OpAmp output.

That is clear.

Now I would like to feedback uC through GPIO some way that I will know which jumper / battery type has been selected (I need to know that in software).
I imagine some additional OpAmps connected to R2/R2'/R2'' but I have no idea how to do it.

I'll appreciate your help :)

simulate this circuit – Schematic created using CircuitLab

Edit 1:

The device is used to measure water pH and conductivity. It needs temperature feedback for pH and conductivity ICs and communicates through GSM. It will be powered by batteries so it needs to be energy-saving. Most of time it sleeps and every 5 minutes it makes the measurements. GSM is turned on (GSM sleep or DC/DC sleep mode) only for daily report or when measurements are out of range.
When it sleeps sub-ICs takes: 1mA (pH) + 0,4mA (conductivity) + 1mA (GSM sleep mode) or 1uA (GSM DC/DC power down quiescent current) + ??mA (PT1000 - not yet determined) + ??mA (uC - not yet determined but low).

Battery's voltage ADC measurement is need to calculate battery percentage of capacity and time-to-live (based on past statistics), additionaly raw voltage display.
For above I need OpAmp or voltage divider. Selecting battery type (input voltage) is mandatory to make calculations more detail. I dont want to do software computing and if-else to figure out if battery is 12V or 3.6V, because it is possible to plugin any battery combination which summed voltage is from 3V to 15V. Of course it is easy to determine from one voltage divider the battery type: 3.2-4.2V for one-pack Li-Ion, 6.4-8.4V for two-pack, and 10.8-12.6V.
Just thinking out loud :)

Getting back to merritum: I need to choose between OpAmp and voltage divider based on energy-saving. Voltage divider (mega ohms) will consume uA the same for OpAmp's quiescent current in shutdown mode.
Im puzzled because at first I thought OpAmp will be more energy-saving.
Whant do you think guys and gals? :)

Edit 2:

Accuracy and resolution.
The ADC is from STM32F091 and it is 12bit so cutting off the noise lets assume it is 10bit.
The worst case is Li-Ion battery which voltage ranges from 3.4V to 3.7V. That give 300mV delta. To represent the percentage I need 0,5% step so the resolution is 1.5mV per step. That is when using dedicated voltage divider.

When using single voltage divider for all batteries types:
The maximum battery voltage might be about 13V (for lead) so I need to scale it to 3.3V => div = 4. When using single Li-Ion I will get with this divider values from 925mV to 850mV so delta is 75mV. The needed resolution is 75mV/200 = 0.375mV. Step for 0V-3.3V 10bit is 3.2mV so 10 times too small. Even if I use all 12bit the step is too small - 0.8mV.

I think I need dedicated voltage divider for battery type or again OpAmp?
Whichever would be more energy-saving??


texts: Why I find a real pole of a transfer function leads to an imaginary frequency and a imaginery pole of a transfer function leads to a real frequency?

texts:
Consider two cases:

What are my mistakes in these calculations?


texts: Is it easier to attenuate a sine wave or a more complex wave?

texts: All other variables being equal, how does waveform complexity of a plane wave affect shielding effectiveness?  Is it easier to attenuate a sine wave or a complex waveform?


texts: do magnetic fields affects wifi signals?

texts:
I have note 4 and I  have putted magnetic cover on it, and now sometimes if signals are low then if I put cover off then I can use my wifi connection and if I keep cover on it then it stops working. Do magnetic field really affects wifi signals?
hope I will get a satisfactory answer.


texts: State Space Model for Variable Mutual Inductance

texts:
This is a hell of a request, but today I have recently introduced myself to the concept of the 'State Space' model. I've understood, to a basic level, how state space models work and I am convinced that state space is the correct method to progress with my current problem (maybe I'm wrong?).

The practicality of the situation is essentially me trying to recreate/model an age old Physics experiment known as the Thomson Coil Induction Ring Experiment and I wish to simulate the experiment via the coupled electrical equations that the ring and coil possess. The experiment was traditionally carried out with a capacitor bank discharging into the coil which in turn produces a changing current which in turn generates a changing magnetic flux density that produces current on the surface of the conductive ring.

Here is the question. I have the following model of two differential equations that I believe successfully describe the relationship between both LRC circuit and the ring. Differential Equation 1 is an LRC discharge circuit that possesses mutual inductance with another RL circuit (represented by Differential Equation 2) that moves away due to the magnetic flux density produced in the LRC circuit from Differential Equation 1, hence there is variable mutual inductance. The equations are as follows:

$$Vc = L_1 \frac{di_1}{dt}+i_1 R_1 - \frac{d}{dt}\left[M i_2\right]$$
and
$$ 0 = L_2 \frac{di_2}{dt}+i_2 R_2 - \frac{d}{dt}\left[M i_1\right]$$

These both expand to the following:
$$ Vc = L_1 \frac{di_1}{dt}+i_1 R_1 - i_2\frac{dM}{dt}-M\frac{di_2}{dt} $$
and
$$0 = L_2 \frac{di_2}{dt}+i_2 R_2 - i_1\frac{dM}{dt}-M\frac{di_1}
 {dt}$$

Since I am new to the concept of state space, a situation like this is most challenging for someone who has only just got to used to the concepts behind state space. To complicate matters further, I am interested in the evolution of the Mutual inductance, not with time, but rather with position, e.g.:

$$\frac{dM}{dt}\cdot\frac{dz}{dz} = \frac{dz}{dt}\cdot\frac{dM}{dz}= v\frac{dM}{dz}$$

As you can see this is a very very large request for assistance with deriving a state space model. I am also aware that this is non-linear and hence, takes more effort to produce results for due to the complexity.

Kind regards, Vhaanzeit


texts: Why some computer peripherals should not be disconnected without turning off things?

texts:
As far as I know, some cables should not be disconnected from computer while it and/or the device is running and persistent hardware damage can occur if they are unplugged errorneously.

Currently the table is like this:

USB, Firewire, Ethernet, HDMI - can connect and disconnect without caution;
VGA Monitor - OK;
Serial port (COM) - OK probably;
SATA - should be more or less OK;
IDE, PS/2 - not recommended;
Parallel port (LPT) - very not recommended;
CPU, RAM, PCI, motherboard to PSU slot, ... - I don't know.

I tried or seen hot disconnections for all mentioned above (expect of LPT and the last point) without any problems.

Why the slow or device can be damaged by sudden disconnection? What happens when some (not all) pins are not connected?

Does it still apply for ( LPT or PS/2 or IDE ) USB adapters? Can they also be damaged or "unplugged cable => burned port" is only for old legacy hardware?

Can a cable with damaged wires (but without any short circuits) damage the port or device?

Note: just software issues (data loss, operating system crash) is out of scope in this question. It's only about hardware failures that cannot be fixed without bying things.


texts: problems visualising the power transfer in a simple circuit

texts:
So I'm having a hard time visualising the equation for the circuit below.
I understand that the answer is -24W, but I can't imagine the circuit in my head..
I've tried to visualise my thought process in the drawing below the circuit, but apparently I'm wrong in my assumptions somewhere.


texts: Voltage divider with potentiometer - Failsafe

texts:
I have a voltage divider circuit producing a reference voltage as follows:

Vref is the control voltage for a regulator, and Vmeasure the output voltage of the regulator, with Vref being regulated to 1.21V.
Now, if RV1 were to fail open or become disconnected (it is connected on a pin header), Vref would fail to 0V. However, I need it to fail to Vmeasure, because otherwise a lot of circuitry may get damaged.
The simple solution would of course be to swap R1 and RV1 and adjust the values, but this cannot be done on this board.
I have tried adding a PNP transistor to bypass RV1 in case the voltage goes too low, but this didn't work as anticipated when RV1 is disconnected:

This results in the voltage being too high when RV1 is connected and no change when connected.
The solution cannot be very complicated as it needs to be bodged onto the PCB.
Am I on the right track with this solution or what would you suggest?