texts:
I am using stepper motor for my CNC machine. Its model number is EM284 STP-42D221-01 by Shinani Kenshi. I don't know any specs of this motor; neither voltage rating nor current rating. I don't even know its RPM. I am using IRF640 MOSFETs to drive stepper motor along with 817B optocoupler.

I am running my stepper motor at 12 V. I have to do diagonal motion so I am running two stepper motors simultaneously.

Problem is when I use 12 V power supply with 4.2 A current rating, my motors are getting hot and also driver circuit is also getting hot. But the motors are running smoothly and are not missing the steps.

When I use 12 V supply with 2 A current rating, both motors are missing the steps but this time both driver and motor are not getting hot.

I don't know where is the problem? What should I do? Either there is a problem in my driving voltage or problem in driving current, or some other issue.

The driver circuit for both motors are in parallel. That means if I use 2A source, then 1A current is going in each driver means in motor.


texts:
Hey all i am just wondering if my drawing below is correct in order to have an arduino detect an on or off led on another board using a optocoupler?

My thoughts of the above drawing is that when the led is on it will trigger the relay inside and send 5v to the arduino digital pin to read. 0v if the relay inside is not connected.

I also would possibly need to tell the arduino digital pin that its an input pullup like this:

pinMode(pin, INPUT_PULLUP);

please advise if this is correct or not.

Im looking to connect the 4n25 to a HM-10 bluetooth module led:


texts: How can I take look at the inside of the atmega1280?

texts:
I want take a look at the memory and at the elements inside the atmega1280.
I compiled Ardupilot sketch and I uploaded it with an arduino.

I started avarice with the following command:

$ avarice --mkII --capture --jtag usb :4242

and I started avr-gdb

$ avr-gdb /tmp/build5831285936308447966.tmp/ArduPilotMega.cpp.elf

I typed:

(gdb)target remote localhost:4242

and this is the answer:

(gdb) target remote localhost:4242
Remote debugging using localhost:4242
0xfffffffe in ?? ()

when I do list it show me

#include <WProgram.h>

int main(void)
{
    init();

    setup();

    for (;;)
        loop();

    return 0;
}

That is not my ardupilot!

I don't understand why I get the ?? symbol after the target command and why I get a different source after the list command.

Could someone explain where is my error, how they work and the reason of those symbols?
More important, how can I take a look inside of the atmega1280?

P.S.: I compiled with Arduino, so I compiled with the -g flag.

Edit:
I used an unofficial jtagice mkii:

and I follow this guide for the setting http://www.diydronesafety.com/topic/72-articleundocumented-apm2x-jtag-technique-and-jtag-for-apm1x-using-only-the-redboard/

So mine is presented like this:


texts:
I'm trying to drive a TPA6120 headphone amplifier with TL072. I use single 24VDC supply with a TLE2426 virtual ground.
The TL072 works well and puts out around 21Vp-p sine wave. But as soon as I connect the TPA6120 amplifier to its output the sine gets clipped to around 17-18Vp-p. That is 6V less than supply voltage. Any idea wahat could cause this?
Looking at TL072 datasheet Figure 6-12 and 6-13, output swing with 1k load (12mA@+-10V) should still be atleast 22V.

The sine looks ok from first TL072 output.(Yellow line on scope screen)
The sine comes out clipped from second stage(Blue line on scope screen)
The signal then enters TPA6120 which is loaded with 16 ohm resistor at its output.


texts: Triangulation Vibration Sensor Impact Detection Position

texts:
I am working on a project to detect the position of an impact using three vibration sensors each one of them linked to a micro-controller(in my case STM32F4) .

Using ADC and UART ,I can plot with a python script the graphic for each of the data received,thus when i do a tap inside the triangle of the three devices(vibration sensor+STM32F4) i can see that there is a delay between the three line chart.

My goal is to detect where the impact has occured and then plot it. I saw that i can do that using triangulation. I would like to do that with a python script and plotting for example the triangle and when an impact occurs inside of it,it shows me its position. As far as i saw,the triangulation is a solution to this but i don't know where to begin or what to do .

How can I do that with triangulation ?


texts:
Good day! I am in the process of adding some right angle bnc female connectors onto my PCB but I have no idea how to decipher the schematic file and have no idea which pins connect with what. The BNC connector I am using is the 1-1337543-0 from TE Connectivity: https://www.digikey.ca/product-detail/en/te-connectivity-amp-connectors/1-1337543-0/A97553-ND/1755940.

Here is the footprint and symbol in eagle. Questions:
1. What is the SHIELD?
2. What is P1*2?
3. Where does the signal connect?
4. Where does ground connect?

Thank you!


texts: 4-20 mA Loop voltage Implementation using XTR115

texts:
I want to Implement 4-20mA current loop using this circuit that is proposed in the IC datasheet.

I used 7805 regulator to Implement Vloop and this is my Schematics.
will this work?
Edit: the load is an 180 ohm coil.


texts:
I connected MSP430 Launchpad to the PC, but when I click download and debug it shows this error

  Fatal error: Failed to initialize.  Check if hardware is connected.
  Check if drivers are installed. Try to restart the computer. Tools
  using the parallel port are not supported on Windows

update: Ok I solved it.  I connected to the another USB port.


texts: I'm working on a new customized motor controller system I've inherited.  The system has a heirarchy of controllers - a PC communicates to an RS-485 serial bus of one level of controllers, and each one of these communicates to it's own RS-485 bus of controllers.  The system uses a customized packet protocol with simple 8 bit checksum and no ACK/NAK scheme.  Maximum packet length is 256 bytes.  I'd like to come up with a really thorough communications test for the system, one I could leave running for perhaps hours on a system testing it as much as possible for any type of data corruption.  What would be the ideal way to do this?  Would it be better to test a known data pattern, or pseudo random data?  If a known data pattern, what should the pattern be?  Would it be better to test short data packets or maximum length packets or varying combinations?  I know there are a lot of good algorithms out there for testing RAM so am eager to learn of how to best test serial interfaces.


texts: How the bandwidth is impacted by the load?

texts:
The bandwidth of electronic parts, like analog switches, is usually specified for a specific load, typically 50 ohm and 5 pF for example.

Now if I have an analog switch with a bandwidth of 1 GHz for a 50 ohm load, how the bandwidth change depending on the load? What appends for, say, a load of 1 kOhm? Is there a way to calculate or estimate the bandwidth for different load values?

Thanks.

(this is a follow-up of High voltage high bandwidth analog mux)


texts:
I am working on a design with 2 12V power supply, one external and one from a battery. The current needed is about 7-8A.
I could have use schottky or simple diode to protect one supply from another but my objective was to manage supply, to use battery only in case of failure from external supply.

I made a small design using PMOS as switch, and it is mostly working fine if I do not connect supplies from one to another.

I have few points that I have trouble understanding.

When the switch between Vsupply and Vbat happens, LTspice shows a huge current surge drawn from one supply to another. I do not understand from where it might come from.

I also have a voltage difference of about 1V between the output and the supply. I assume this voltage is due to the selected PMOS, but I do not understand which parameters as an impact on the design. I have selected those PMOS randomly.

If you have any suggestion regarding the selected components, I am interested.(The amplifier has to have an extremely low supply current).

Also, as I am low on space for my PCB, I was thinking about using SOIC Dual PMOS (such as DMP3036). But when I look at the datasheet I see a Maximum Continuous Body Diode Forward Current of 3A. I don't understand where this current impact the design. I do think that in my design, it will reduce the maxium current supplied by each source, but I am not sure. What is the difference with the drain current ?


texts: Inrush current with capacitors connected to USB in parallel

texts:
I did a project that connected to the PC USB. When the PC is being shut down the Vcc (5 volts) is halted. But I need the voltage source to stay for extra milliseconds after the voltage halt.

For that I used capacitors in parallel (both electrolyte and ceramic) connected between the Vcc of the USB to the GND.

I am afraid that connecting these capacitors without any resistors will cause a spike in the current at the beginning of power-on of the system because the capacitor will be charged in 0 [sec].

Is it safe to rely on the parasitic resistance of the capacitors and the wires and the current limiter of the PC USB?


texts: A novice question about mixed signal IC design

texts:
As far as understand, a digital IC like a DSP can be design by RTL methods and by using languages like Verilog and VHDL.

And if I'm not wrong, we cannot yet program pure analog chips by using a language so SPICE simulators are used for design(?)

But for a mixed signal design of a chip, does that mean one expert desing the digital part(by using HDL) and the other expert analog part(by using SPICE)? So it takes two expert desing engineers for a mixed signal design? And they integrate it together in a way?


texts: Control 12V MOSFET with 5V, with PMW pass-through?

texts:
I am new to electronics, and still tying to fully wrap my head around MOSFETs. I have a few questions about controlling a 12v MOSFET using only 5v to the gate, and an incredibly small amount of current.

Here's the situation:
I have a 48V power supply which I am converting down to 12V, with a maximum 33A output current. Connected to this 12V output current, is a 12V motor, and an Arduino. I would like to control the motor using one of the Arduino's PWM ports, and a MOSFET, to minimize current draw through the arduino.

Unfortunately, the Arduino's PWM ports can only provide 5V. The MOSFET that controls my motor will (I think) need to be 12V, and what I have read on the subject tells me that controlling a 12V MOSFET with a 5V gate leads to... Bad things. That is my first question -- what will happen if I flat out try to do this?

My second question is this:

How can I create a circuit that will allow my Arduino to control the 12V MOSFET using a 5V, 4-to-40 milliamp current, while still having the MOSFET reacting quickly enough to allow for PWM to reach the motors? What are the specifications of MOSFET that I will need to do this?

The most important question is, of course, what are the mechanics behind all of these things? Talking to people, I hear them talking about using a transistor as a "low impedance source", and to be honest, I don't understand what they mean. How does that play in the whole thing?


texts:
I'm working on a project where there will be 3 USB devices and a Qi transmitter that are hooked to a USB hub board. I just need USB High-Speed, not 3.0+. The 3 USB devices would consume total of ~1A.

I wanted to know that although theoretically possible, is there any issue with powering this hub via a USB fast charger. The rationale behind it is that USB fast chargers are easily available now and provide the required 5V/2A.

If yes, is there any advantage of using USB Type-C rather than microUSB?


texts:
I am using an external pullup resistor on my input pin, and a switch connected to GND. It is like in the picture below. In the below picture, when the switch is open, the MCU input pin will see a logical high. I want to reverse this condition and see a logical high when the switch is closed. Should I use an internal pull up or pull down resistor to accomplish this? Also, what will happen if I use a pull-up? What will happen if Vcc is connected to Vcc or GND is connected to GND. I am really confused.

Regards,
Karan.


texts: Thevenin equivalent, of circuit with one voltage and one current source

texts:
I am a Computer Engineering Student, and we have a lesson called Electric Circuits.
I am trying to understand Thevenin's Theorem, but there is a circuit that confused me.

simulate this circuit – Schematic created using CircuitLab

I removed power and current source to calculate Rth and if I am not wrong it is 1Ω.
I also calculated Vth, with the voltage source back on, to be 5V.

My question is what happens with the current source? When I put it back on the circuit, I shorted the voltage source, but at the same time this shorts out the current source. So, is it going to affect the rest of the circuit, or not?
How would you solve this?

Probably a silly question, but I am inexperienced with this stuff.
Thanks in advance.


texts: I have been playing around with an op-amp design using TINA from Texas Instruments. I have selected the LM301A. TINA says that this op-amp has a dominant pole at 5 Hz. I have put the circuit below. VG1 is feeding in a 2 Hz sine wave at 50 mA. The supply is \$\pm 5\text{ V}\$. When I simulate this circuit the -3 dB point seems to be around 38 kHz. I am obviously doing something wrong, I just don't see it. Can anyone offer any advice?


texts: Multiplexer that works by measuring voltage on select input?

texts:
Is there any small MUX device that would provide 8-64 inputs, which reads from a single select input?

I'm thinking that instead of using e.g. 3 select inputs to set which signal input to use, such a device might read a single input and select based on PWM or on voltage.

Thus, an Arduino user could use a single selector pin to configure which input is read from.


texts: How to amplify the resistivity range of a rheostat

texts:
I have a black box DC to AC inverter with a 5 kΩ linear taper pot wired to it that acts as an LED light dimmer. I have no idea how the circuitry of the black box is composed - it is encased in a potting compound. The pot is wired up to the wiper and one end (like a rheostat) and the lights get brighter as the resistance increases.

I want to control the dimmer with an original dimmer switch.  Unfortunately the original dimmer rheostat only has a 10Ω linear taper range – just a wiper across a wire coil and the resistance decreases as I turn the knob up – opposite of the 5 kΩ Pot.

I'm trying to find a simple circuit that will magnify and invert the 0-10 Ω range to a 0-5000Ω range to control the inverter. I'm not sure if an OpAmp can do the trick. I do know that the voltage running across the 5 kΩ pot is about 8 V perhaps I can use the OpAmp to mimic the expected voltage drop?

An Arduino and a programmable digital potentiometer seems overkill. Also, I haven't liked any of the options I could find to swap the wire coil with something of the right resistivity range.


texts: STM32 Nucleo L053R8 - Not able to select number of conversion

texts:
I am trying to use multiple ADC channels via DMA. Something like this over here:
enter link description here. The issue is however, that I cannot choose the number of conversions. I am not even given this option.
I am using STM32L053R8 with Nucleo board.
Any help appreciated!


texts: LUT vs. hard IP based multipliers on Spartan-3 FPGA for constant coefficient multiplication

texts:
Before I get to my question, here are the specs for the board and synthesis tool I am using:

Family: Spartan3
Device: XC3S200
Speed: -5
Synthesis Tool: XST

My 4-bit multiplier is in my design's critical path. I would like to reduce the time multiplication takes so I can reduce my critical path and increase my clock frequency.

I can use CoreGEN to instantiate LUT based multipliers,  LUT based constant coefficient multipliers, hard multipliers, and hard constant coefficient multipliers (which I think might just be hard multipliers with one input hard wired).

I am thinking that if I use 15 LUT based constant-coefficient multipliers (or maybe 11, can take care of cases 2,4,8 with shifting and 0,1 are trivial) that I can break this critical path down a bit. My design constraints prevent me from pipelining these multipliers; I need them to just integrate into my combinational logic path.

Would this be faster than just using a hard multiplier? Or would a normal LUT based multiplier be faster than either option?


texts: Trying to understand flyback diodes and general diode orientation

texts:
Let's start with this:

I know the top image is of a flyback diode. I also get that its purpose is to protect the power supply from a voltage spike when the electromagnet releases. So I've gotten that far.

The second diagram is what gets me, I guess. In this diagram, I am assuming the diode is being used in a more conventional setting and it is wired inline (in series?)" The cathode stripe in this picture, though, is toward the negative end of the circuit, which is exactly the opposite of the way it is being used in the former picture. So, that's confusing to me. Why is the polarity different between the two? Also, why do I need to wire a flyback diode in parallel? Shouldn't I just be able to put it inline in the positive wire to protect the voltage source? (And at that point, would I put the cathode end toward the solenoid?

I'm just trying to wrap my head around orientation and application here. I see lots of videos explaining how they act as "valves" and can rectify AC current, but very little about how flyback diodes work (and why they are wired in parallel).

Still getting my sea legs, here. Thanks for any helpful input.


texts:
I have an RGB LED that I'd like to change from green to red when a circuit is completed.  While I know this is very simple with tools like an Arduino, I'd love to not use a microcontroller.  Would it be possible using basic components (which can certainly include transistors, diodes or even common ICs like a 555 timer) to achieve this?  If so - how would I connect the components?

Clarification: I'm using a common anode RGB LED (a lead for each color plus ground - four in total).  I'd like to have it be green when a switch somewhere in the circuit is open (not connected) and red when the switch is closed.  The switch is not connected to anything else.


texts:
Would the diode and the fuse protect the other components if power wiring is reversed?
Is the polarity of the diode correct?


texts:
Ultrasound machines tend to be pretty bulky. Even the portable ones often are hefty items that look like those old Compaq portable computers from 1985.

Very recently there are some smaller ones like the Nanomaxx, but by and large they are still usually bulky machines. The smaller ones tend to have signified reduced beam resolution.

Do these machines require some special kind of electronics or large power supplies that make the machines so big, or is it just a case of medical technology being behind the curve and using outmoded computers from yesteryear?


texts:
I am looking for a Buck-Boost converter design that can take an input of 85 or 90 vrms to 265 Vrms. I would like the output to be in the range of 112-115V (DC) and current at least 150mA (dc). The overall power output at least 17Watts

Please Help I’ve been searching for a few days now and cannot find.
*Found a few by Fairchild however they will not work due to size of the transformer *


texts:
I'm building a simple pulse generator with a TL494 in single ended configuration.
My plan is to set the frequency between 20Hz to 1kHz and duty cycle between 0% to 45%.
I will adjust that with a potentiometer.
How can I adjust the duty cycle? I've tried by adjusting  PWM input, comparator or dtc. I test it with frequency below 100Hz and an LED at the output. I can see the blinking LED as a result, but I can't get a duty cycle between 0% to 45%. I just get about 0% to 100% and random duty cycle.
Please help me or show a circuit.
Edit:
Heres's the schematics I've tried:

At first (err amp sett) and second (comp sett), I got unstable up to 50% duty cycle.
With last schematic (dtc sett), I got a stable duty cycle, but it give zero to 100 percent not 50 percent, and also the LED stops blinking or stays  on at left or right edge of pot.
I also try to replace the IC, but still same.  When I replace it  with a KA7500, I got the expected result.
Sorry for my poor hand drawn schematic, I'm far from my home and computer at this moment.


texts:
I have some questions about capacitor and the circuit shown below:

The original signal including noise is shown below:

There are three waveforms shown in one picture.

The top one, middle one, and last one is connected to 4.7µF, 0.1µF, and 100µF respectively. Why is the top one smoother than middle one? Why is the last one out of shape and attenuated? If I change GND to 2.5V, is it able to filter out the noise? If I can filter out the noise only with capacitor, why using RC?


texts:
Impedance is made of resistance and reactance which is capacitance and inductance. I read that increasing resistance increases noise, but what if capacitance or inductance is increased, does the noise increase too?

The way I see it,capacitance and inductance act like resistance too, they too resist, only difference is that their "resistance" is frequency variable unlike normal resistance. Also normal resistance dissipates energy, while capacitance and inductance store energy. I am not sure if this have impact on noise.

Example: I have three identical signal sources outputing 100 Hz sinewave, I want to attenuate it by some amount. One sinewave goes through 1MΩ resistor, second through capacitor that have 1MΩ capacitive reactance at 100 Hz and third sinewave goes through inductor with 1MΩ capacitive reactance at 100 Hz. How high will be noise at each case? Which of the three sinewaves would suffer worst SNR degradation?


texts: UV LED operating above Designed Voltage Hazard?

texts:
I have a 5mm High Brightness UV Led that I bought from Radio Shack that states
Wavelength 405nm ( typ)
View angle 20 Degrees
FW current 20mA
FW supply 3.3V ( typical), 4.0V (max.)
part # 276-0014 pkg. of two

I have put this Led in a key chain light that has two 3V batteries in series making 6V output to the LED. 2V over Max. Will this change the wavelength of the led and intensity ? Is it hazardous to the eyes looking directly at it from a few feet away or looking at its reflection off objects with unprotected eyes. Thanks
Light has a purple violet tone


texts:
I'm having trouble with MCP73833. It's 1S lipo charger powered from USB. I followed this figure from application note:

My schematic:

Battery connectors are X4 and X5, load is connected, USB is disconnected,

The problem is on the line marked in my schematic I measure 2.1V. I don't know what might be wrong with this design and how it can get in there. D5 schottky diode prevents this situation. Also its not IRLML2244 fault. MCP73833 10, 9 pins are the only way. I checked block diagram of MCP73833 and the only thing that bothers me is the Direction Control. Is there a option that it might get though Vbat and appear on VDD?

The question is: How 2.1V appeared on marked line?


texts: Stepper motor voltage / resistance per phase

texts:
I am trying to run this stepper motor (XY42STH34-0354A), but I am encountering two odd issues with its performance: slowing of the motor in 1/32 microstep mode, and a "soft cap" of the RPM where the speed of the motor barely changes despite increasing the RPM parameter.

Here are the motor specs:

Rated voltage: 12V

Current/phase: 0.35A

Resistance/phase: 34ohms

Inductance/phase: 33mH

Holding Torque: 20N-cm

I'm currently using a DRV8825 stepper motor driver with the motor using a 30V supply and am controlling it with an Arduino Mega, using this stepper library I found online. I believe that all my wiring is correct, and I've properly set the current limit on the DRV8825 to the rated current limit of 0.35A following the instructions on the Polulu website. The motor runs smoothly within a certain RPM range at all microstep settings.

When I use the 1/32 microstep mode of the DRV8825, it is noticably slower (~20%) than that of the other modes (1/16, 1/8, 1/4, 1/2, 1) for the same RPM setting, but other than that, works great (smooth, no rattling or other odd behavior). I think the motor may speed up slightly as the microstepping setting gets more coarse (towards fullstepping), but it's small enough that I really can't tell.

The second thing I noticed was that despite increasing the RPM setting, my motor hits a maximum of about 4-5rps. There is a range of RPM settings (300-900RPM) in which changing the RPM value won't result in any noticable difference in the speed of the motor, which is what I refer to when I say "soft cap". Exceeding that limit causes the motor to jitter.

Could anyone help me understand why the motors are behaving this way? Looking at some other NEMA17 stepper motors online, I see that they have a lot lower voltage ratings (2-3V) but much higher current/phase (1-2A). Could it be that the driver I chose isn't correct for my stepper's specs, or that the lower-voltage higher current types run faster or better? Thank you.


texts: Why do some wires in my turntable have plastic covers over them?

texts:
I recently purchased a turntable.  I spent a good chuck of cash on it - and it sounds great but has trouble keeping speed.

I am starting to retrofit it with a brush less motor that will be controlled by an Arduino.  When I opened it up the first thing that jumped out at me was that some of the wires were covered by a plastic tube that is pretty nasty and looks like it has been accumulating condensation for the last 40 years.

Why are these wires covered in an extra layer of plastic?  Would it be ok for me to just replace the wires?

Here's a photo of what it looks like.


texts: Capacitor Voltage Hold up (During Input Power Interruption)

texts:
I want to understand how long a capacitor can provide the stable voltage for a given load current, in the event of an input voltage interruption?

Suppose, I have a single 100nF input capacitor at my 12V. Across the capacitor, I have a load of 50mA. My stable input voltage is 12V.

Suppose, the 12V drops to 0V for some, say 100us, and then comes back up to stable 12V. Will that 100nF capacitor be able to provide the stable 12V with 50mA to the load during the momentary power interruption? If not, how long will it provide the stable 12V maintaining the same load current?

Is there any formula or a way to figure out the minimum capacitance needed to support this requirement? Or how long the capacitor can provide the stable 12V with the same 50mA Load?


texts: Why AND gate is considered as Positive Logic and OR gate as Negative Logic


texts: LTSpice: Produce Bode Plot for Compensated & Uncompensated Boost Converter

texts:
I am designing a product which uses the LTC3122 as a 5V-12V boost converter (datasheet here). This particular device provides the ability to add gain compensation, phase lead, or both. In my case I am only using the gain compensation network, as seen in the image below:

R13 and C28 form the phase lead network (marked as "DNP" in my case since they are not populated), and R12 and C26 form the gain compensation network.

I calculated these values based on the requirements for my project, and now I would like to illustrate the effect that adding the compensation has on the output of the system. I want to do this by generating two Bode plots - one for the circuit with R12 and C26 included and one without. However, I seem to be having some difficulty generating these Bode plots. I attempted to perform an AC simulation of the design in LTSpice but received a warning saying that "This simulation calls a time-domain model...", effectively saying that the simulation would be pointless. I then tried following the process described in this link to obtain a Bode plot, but the simulation has been running for hours and still has not completed. The status bar at the bottom of the LTSpice window says it is 0.3% complete after running for almost four hours. I don't expect it will be able to find a solution. Below is an image of the LTSpice schematic pane:

What other methods could I use to obtain the Bode plot(s) for this boost converter? I went through the datasheet and, while it contains a large number of equations and formulas for poles and zeros, I'm still not convinced I have enough information to determine the full closed-loop transfer function of the model. I would greatly appreciate some assistance from someone more experienced with LTSpice and/or obtaining Bode plots of boost converters than I am. I am basically looking for a Bode plot like the one shown on Page 17 of the datasheet (below), but I want to be able to generate my own so that I can show a side-by-side illustrating the differences between the responses of the compensated vs. uncompensated systems.


texts: Connecting DAC to line out and headphones

texts:
I am designing a PCB with a stereo DAC UDA1334BTS and two stereo jacks -- one for "line out" and the second one for headphones. My original plan was to connect the DAC output both directly to the "line out" jack and to an input of an amplifier TDA1308 which will be connected to the headphone jack (and use the recommended application schematics for both of them).

However, the amplifier is an inverting one, which is not optimal for my application -- the two outputs would have different phases and the person listening to both headphones and line out would be confused.

What is the correct approach for this kind of application? I can think of two possible solutions:

Put an inverting amplifier to the "line out" signal as well so that both of them are inverted
Use the amplifier in a non-inverting mode (Is that even possible? All recommended applications for similar amplifiers I've seen use the inverting mode)


texts: Can I put a resistor in parallel with LED to limit current consumption?

texts:
I want to power one 3V LED with a 3V source. Let's say I'm using a 10 Ohm limiting resistor, and the LED eats 20mA of current. Using a CR1225 with 50mAh capacity that will last for about 2.5h.

What if I connected another 10 Ohm in parallel with the diode + limiting resistor? The voltage across would still be 3V - enough for the LED - but the current going through the LED would be halved. What about the total power consumed by the circuit?

I don't mind if the LED gets dimmer, I'm ok running 10mA or less through it. All I want is to increase the amount of time it emits light.

Would that work?


texts: What's wrong with my switch mode power supply circuit?

texts:
I'm using a TPS54383 dual output SMPS IC from TI, putting out 12V and 5V; at least in design. I created a schematic and board and had it sent out to OSHPark and soldered it all up today and only the 12V side works!? On the 5V output I'm only getting ~.82V.

Any ideas?

**Side note: I am using two different types of inductors, which I think may factor in here the 12V side uses: 12V inductor,
and the 5V side uses: 5V inductor.

Also I've modeled up the circuit in TI TINA and simulated it and all appears well..see below:


texts: Current on human with grounded electrical device

texts:
Assuming I have a grounded electrical device, for example a microwave.
The left drawing shows that the phase wire is connected (due to a fault in the wire) to the microwave case, and an electrical path is created from the phase, to the case, and from there diverging to the human (displayed as a resistor) and to the grounding.
The right image shows the equivalent circuit.
I couldn't understand however, how does the grounding helps reduce the current on the human?
There is a voltage of Vphase on both the human and the resistor to the grounding (it is the equivalent resistance of the grounding wire). They are connected in parallel. It appears that the current on the human is Vphase/R_human whether the device is grounded or not. So how does the grounding help?
Also, what is the potential of the case during regular times (I thought it it probably 0) and during faulty times (thought it is Vphase, beacuse now Vphase is directly connected to it) ?


texts:
This came up when a student asked me. A simple question one might think. Except... how to define one without tautology? That is, without using the word "sine" (or cosine for that matter). Wikipedia does not help, although the moving disc might be of relevence.

In short, I suspect his teacher has given him a severely hard problem, though I may be wrong.

This came up as part of an electronics course. So presumably any answers can be derived from the characteristics of various components/circuits.


texts:
My professor had told us that Bilateral elements have V-I characteristics which are symmetric about the origin.
However, in an exam, we were asked to draw the V-I characteristics of a non linear, bilateral element.
The given answer was:

However, shouldn't "symmetric about origin" imply something like:

?
Or have I misinterpreted the term "symmetric about the origin"? I am fairly sure that in the normal context, this corresponds to curves like my second image.


texts: ORing mosfet controller with ability to switch off the load

texts:
My system is powered from a wall adapter and backup SLA battery.

simulate this circuit – Schematic created using CircuitLab

Since the voltage of the wall adapter is higher than the SLA, I have ORed the two so that the battery will be used only when wall is not available. In the event that wall is not available and the battery is discharged, I would like to disconnect the battery from the load to prevent further discharge. I could simply place a high side switch before the ORing diode, however I thought using an ORing mosfet controller would be smarter since it can do the ORing with better efficiency and act as a switch at the same time (win win!!).

I found the TPS2419 ORing contoller with enable and LM5050. The enable pin on these controllers allow me to turn the high side N-mosfet off, but to my surprise this does not disconnect the load as the mosfet is connected such that its body diode will conduct (see figure below). Every other ORing controller I have seen also uses the same configuration. The data sheet of the LM5050 even mentions that current will still conduct when the external mosfet is off.

I have also looked at power multiplexer ICs but they are rated for lower voltages.

My question is, is it even possible to use the ORing mosfet as a load switch? If not, why is the mosfet connected that way and what is the purpose of the enable pin?


texts:
I'm trying to get my head around the circuit theory behind the
high side NMOS switch, here is the shematics:

My question is not about whether this is a good or a bad way to make a high side switch (I know it is bad), but really how to compute the value of the voltage across the resistor for a given transistor and resistor value based on voltage on the gate ?
What data from the transistor's datasheet is used there? What are the equation that allow to make the calculations (like in the figure for example)?

Thanks :)


texts: Driving VCSEL, issue with forward voltage

texts:
for my project i am using max3799 IC and VCSEL.I have designed 4.layer PCB board and assembled max3799 IC and VCSEL also all other passive components specified in max3799 IC datasheet. this max3799 IC has 17 registers to modify according to requirements. Using rasp-pi i can successfully access registers and modify them.

for reference i am attaching datasheet of VCSEL and PIC1, PIC2 about forward voltage.

TO drive VCSEL it needs forward voltage of 2V and forward current of 6mA. but i am getting forward voltage of 1.15 V and forward current of 7.8 mA. So, VCSEL is not lasing.

PIC1 shows ideal working condition when VCSEL connected to MAX3799 IC

PIC2 shows my board working condition when VCSEL connected to MAX3799 IC

enter image description here


texts: Why don't the minority carriers combine with the majority carriers in a PN junction?

texts:
I wanted to start this question by giving my understanding of the make up of a PN junction. I do this so that you can pick me up on anything that I may be getting wrong in the lead up to my question.

I have been doing some research into PN junction diodes and understand that you have one junction which is formed by a p-type region and an n-type region. These two regions have been doped with impurities to give an excess of electrons (free electrons) in the n-type region and a deficit of electrons (free holes) in the p-type region. However due to imperfect manufacturing techniques, we also get minority carriers in the p and n type regions which means that the n-type has some atoms which have a deficit of electrons (free holes) and in the p-type we have some atoms which have an excess of electrons (fee electrons).

Now my question is this - how is it possible that these minority carriers exist? Wouldn't they just combine with the majority carriers?


texts: Finding the value of a capacitance in a dynamic RAM cell? (Digital Electronics)

texts:
I had this problem in my digital electronics final. I want to know how to solve this, although I'm going to use different values since I don't remember the exact values from the test.. I'm going to write out my solution as well, but I only did this solution because I had seen similar problems, I don't understand the reasoning or even know if it's correct. My goal is to understand this, as I feel like I understood every other part of the course pretty well. But electronics has been very challenging to me, as I'm a computer engineer.
Problem information:
The following sketch shows the circuit for a dynamic RAM cell.

The transistor is an NMOS. \$V_{DD} = V_{WL} = 3V, V_T = 1V\$ When there is a read operation, BL is pre-charged to \$\frac{V_{DD}}{2}\$. The bit line capacitance \$C_{BL} = 0.1pF\$. Determine the minimum value for the cell capacitance \$C_C\$ so that during a read operation the change in voltage in the BL is at least 10mV. Ignore body effect.
My solution:
For logic-1 the voltage in \$C_C\$, \$V_{C_C(1)}\$ would be \$V_{WL} - V_T = 3 - 1 = 2V\$.
For logic-0 the voltage in \$C_C\$, \$V_{C_C(0)}\$ would go down to 0V.
Logic-1:
The professor has used this formula few times, I don't really know the reasoning behind it. When I asked, they said conversation of energy. I guess I just accepted that, because it seems like it'd make sense. Here it is:
\$C_C * V_{C_C(1)} + C_{BL}*V_{C_{BL}(1)} = V_f * (C_C + C_{BL})\$.
So we know all these values, we can plug em in:
\$C_C * 2V + 0.1pF * 1.5V = 1.51V * (C_C + 0.1pF)\$
And we solve for \$C_C\$, so \$C_C = 2.04fF\$
Logic-0:
Using the same formula as before:
\$C_C * V_{C_C(0)} + C_{BL}*V_{C_{BL}(0)} = V_f * (C_C + C_{BL})\$.
We plug in our known values:
\$C_C * 0V + 0.1pF * 1.5V = 1.49V * (C_C + 0.1pF)\$
We find that \$C_C = 0.67fF\$.
Conclusion:
When we have logic-1 we need a cell capacitance \$C_C = 2.04fF\$, and when we have a logic-0 we need a cell capacitance \$C_C = 0.67fF\$, in order to have a \$\Delta V_{BL} = 10mV\$. If we made the logic-0 \$C_C\$ any bigger, it would just cause the \$\Delta V_{BL}\$ to be higher, which would be fine. If we made the logic-1 \$C_C\$ any smaller, then the \$\Delta V_{BL}\$ would be less than 10mV.
Therefore, the answer is \$C_C = 2.04fF\$.
Is this correct?


texts:
I made the bellow circuit on breadboard, but my first row of leds ( each directly after the resistors) is not lighting up. What are the possible reasons for it? I tried swapping leds around and again, the LEDs on that position dont work.
The LEDs are mixxed , 2 of them are from a different set from the rest, all are red, and based on online reading I made the assumption of 1.8 volts. Resistors are 180 Ohms.

Update

The two that are different seem to take 2.2V...


texts:
In optical LIN converter PCB there is a weird element glued:
A plastic ring with resin/ plastic fulfillment.

Is it some sort of local coating or chip-on-board encapsulation?
There are no elements in this area on the opposite side of PCB, just 2 Vias.


texts: [Last Update]Simulating an RLC circuit with the 1N3880 in ngpice did not show any results or graph

texts:
Im trying to do a transient response analysis with ngspice/gnucap and gspice UI of the next RLC circuit   (corrected the source polarity), to find the damping effect in the system.

That with the next command

 gnetlist -g spice-sdb -o rlc.net RLC.sch

writes the next spice file

* gnetlist -g spice-sdb -o rlc2.net rLC2.sch
*********************************************************
* Spice file generated by gnetlist                      *
* spice-sdb version 4.28.2007 by SDB --                 *
* provides advanced spice netlisting capability.        *
* Documentation at http://www.brorson.com/gEDA/SPICE/   *
*********************************************************
*vvvvvvvv  Included SPICE model from 1N3880.mod vvvvvvvv
.MODEL 1N3880 D (IS=2.01E-11 N=1.70 BV=1.33E+02 IBV=1.00E-05 RS=1.24E-02 CJO=1.19E-10 VJ=.75 M=.26 TT=1.44E-07)
*^^^^^^^^  End of included SPICE model from 1N3880.mod ^^^^^^^^
*
*==============  Begin SPICE netlist of main design ============
V1 1 0 pulse 0 220 0 1u 1u 1k 2k
.options TEMP=25
C1 4 0 2m
L1 3 4 0.05u
R1 2 3 160
D1 1 2 1N3880
.end

then inside ngspice running in a terminal

 >source rlc.net

Circuit: * gnetlist -g spice-sdb -o rlc.net rlc.sch

Try to do the transient analysis

 tran 0.1ms 5ms
Warning: v1: no DC value, transient time 0 value used

Initial Transient Solution
--------------------------

Node                                   Voltage
----                                   -------
1                                            0
4                                  -2.3973e-18
3                                  -2.3973e-18
2                                  -2.3973e-18
l1#branch                                    0
v1#branch                           1.0148e-36

No. of Data Rows : 79
ngspice 65 -> plot 1 2 3 4

Still gives something like this

Still different from what I was expecting for, at this point what I want to see is the current in the resistor. I have updated with a pulse source as suggested, but it still does not work as desired.

Update 2
There were various things that was messing around.

From the beginning I was trying to plot the current not the voltage, so ngspice did not do this, as explained and suggested here.
I'm using ngspice 30 so the work around of adding the directive

.options savecurrents

should work but when trying the order

plot @R1[i] vs v(1)

does not worked too.

wrong syntax's
From another circuits done, and as commented by @sstobe, the right way to plot would be

plot v(1)

This indeed plot the voltage 1, the voltage at node 1 and so on...
The way i did before I was telling to ngspice to plot the integers 1,2,3.. that's why the graphs.

Wrong source

I changed from a DC to a pulse one since its a transient simulation, as noted by @a concerned citizen.

The time of simulation

I was choosing wrong the values with

tran 0.1ms 5ms

But this was too much time and the response is so fast that in this period cant be seen.
So I adjusted to

tran 0.1us 5us

That finally yield

but since the idea was to plot the current this could not be done.


texts: Homework questions with Compensated Attenuator

texts:
This is for my electronics course and this is for our homework. It covers an RC filter network which I found is called a compensated attenuator. My class which we should've covered a lot on filters, we didn't. So I'm a little lost on the problem

The circuit we reference is theveinized to show how the LPF and HPF can be extracted from the network and how their outputs can be summed to find the output of the network shown at the beginning. That part I understand, but when we go to the problems(we are doing 1,2 and 3) I am totally lost on all of them.


texts: For mainstream computing what are the practical advantages of 64-bit register size CPUs given the needs of today and the near future?

texts:
I understand one of the limitations of 32-bit processors is the inability to easily address more than 4GiB of RAM, which is a present day need even for mainstream computing on phones, tablets and laptops.

What are some other mainstream computing advantages of a 64-bit register size architecture as opposed to a 48-bit register size architecture?

Please cite relevant sources or provide detailed reasoning in your answers. Number of bits which are powers of two are better does not provide a technical justification.

Of course if price were not a consideration then the more bits the better, also we obviously cannot predict distant future needs.

A wider bus may be able to move data more quickly but the bus size doesn't always have to match the register size does it? Also a CPU with more transistors and more lines may be forced to run at slightly slower clock rate due to physical limitations perhaps?

With 48 bits you can address 256TiB of RAM: plenty of space to be useful for at least the next few decades. It seems that, generally, 32 bit numbers are already plenty large for most integer and decimal calculations for mainstream programming, making 64 bit seem wasteful. 64 bit applications end up consuming more RAM and the processor itself ends up with a lot of wasted transistors in the ALU, control unit and bus for bits that simply aren't needed. All that stuff takes up extra silicon space which could be used to simply make processors smaller and cheaper or could be put to better use in the form of caches or additional cores.


texts:
I have built a high voltage voltage-divider so I can use a low-cost single-ended HV supply at multiple DC output voltages simultaneously. The current delivery is very low at 50 uA max and the purpose of the circuit is to provide voltages for assessment of in-house HV measurement circuits. My HV supply goes up to 10 kV and I have used 5 x 250 MOhm resistors in series with a 5 GOhm resistor to GND. Theoretically this voltage-divider should produce voltages at 100%, 96%, 92%, 88%, 84% and 80% of the supply voltage.
The divider has been built using good quality components that are all rated for these voltages. The 5G resistor is Ohmite SLIM-MOX10803 with a maximum voltage of 20 kV and the 250 M resistors are Stackpole HVA series with a maximum voltage of 8 kV. So yes, the 10 kV should not go across a single one of the 250 M resistors, but the chain of 5 is perfectly fine. The resistors have been soldered together very nicely and are suspended between banana plugs that I will use to access the voltage output at each step of the divider. The components and HV supply are all nicely enclosed inside a plastic container. All components have been cleaned with isopropyl alcohol and given a final spray down with contact cleaner to remove any oil, flux, or other unwanted residue left over from assembly. The entire assembly "works" in that the HV supply always produces the correct output and does not seem to be over loaded by the voltage-divider, and there is no sign of arcing, corona, or discharge.
The signals are all DC and the voltages are measured using a 1:1000 HV probe (CalTest CT 4026, 200 MOhm input impedance) connected to a Rigol oscilloscope (MSO5074, 1 MOhm input impedance).
However, what I find is that the voltage divider does not work as intended. Instead of producing the % outputs listed above, I get 100%, 47%, 30%, 23%, 18%, and 15% of the maximum voltage. I do not have a mega tester to measure the resistance of the 250 MOhm resistors, but they are good quality components from DigiKey, and I am assuming that they are OK.
Can anyone please explain why this divider does not work as intended? What modifications should I make to improve it? Thank you.


texts: IAR Embedded Workbench, SmartRF Studio, CC1120/CC112x, where to start?

texts:
I am a newbie to Texas Instruments CC1120 radios. Where do I start? Also, what should I be using to program them? SmartRF Studio or IAR Embedded Workbench? Both are provided on the official Texas Instruments website.

Note: This question already has an answer.


texts: Instrument amplifier gain setting and REF pin setting on INA232

texts:
I'm trying to amplify O2 sensor output KE-50 with instrument amplifier INA232. Here is datasheet for INA232 with 55x Gain and REF input connected with GND. After do PCB assembly, with 50mV input, voltage output is only 10mV, but my desired output is 2,75V.

Could you help me to troubleshot this issue?


texts:
I've looked at other questions "Voltage sources in parallel", but don't answer my specific problem.

Imagine the following circuit:

simulate this circuit – Schematic created using CircuitLab

I have a solar powered charge controller that, ideally, can deliver 30A at 14.0V, and a battery that, ideally, can deliver unlimited current at 12.8V.

Which laws can tell me something about how this circuit will behave?

For example, if the load is a 50W LED, it would need 14V at 3.57A. Would all the current and voltage come from the CC, because it has a higher voltage?

When the total current would be higher than 30A, I suspect the CC would fail to sustain the voltage.


texts:
I'm a beginner at using LTpice. I want to build a circuit that monitors the voltage level of a battery. This is an ideal circuit to monitor the Voltage level in 12-volt Lead Acid batteries used in Inverters. I've already built the circuit, though I"m not sure if I have it right and I'm also not sure how to run it. The goal is to have one LED turn on and the other turn off for a voltage of 13.5V and 10V I have a description of the desired circuit below:
This is an ideal circuit to monitor the Voltage level in 12-volt Lead Acid batteries used in Inverters. For the perfect operation of Inverters, the battery voltage should be between 12 and 13.5 volts. A fully charged battery shows 13.5 volts. If the voltage reduces below 10 volts, the Inverter will not give back up. Moreover, if the Inverter is continuously charging without attaining 13.5 volts, it indicates that the battery is not accepting and holding charge.

The circuit is too simple and uses only a few components. It shows three indications.

If the battery has 13.5 volts, Green half of the bicolor LED lights.
If the battery has 12 volts(Normal) LED will be Off
If the battery voltage reduces below 10 volts, Red half of bicolour LED lights.

Any information would be appreciated. Thank you


texts:
I've been trying to make ESP8266 wifi bridge between my landline phone and my mobile to map landline phone on my mobile (VoIP project). I've look for sufficient hardware for ADC at most 8bit bit stream and then use UDP to deliver audio package to mobile. Also I've considered DTMF IC to dial or respond pulse tone.

My problem is I don't have analog  design skill to find min and max specification needed for this project. I don't know  how to select   analog circuits or Audio  codec IC's among plenty of possible options  for this matter. Any advise is really appreciated.


texts:
I need my Arduino to communicate with a fairly sensitive 3.3V I2C device, and am using a Bidirectional Level Converter to step down the voltage.

However, I still need a 3.3V source (for the I2C device and Level Converter), and the Arduino shield I am using is blocking the 3.3V pin.

My question to you all: what is the best (easiest/cheapest/most efficient) way to get 3.3V to that I2C device?

My options as I see them: make a voltage divider from the 5V (pictured), buy a $1 voltage regulator, or do solder-surgery on the ardu-shield so I can use it.

Edit: I should clarify this is NOT a small stationary project. The choice needs to be durable and repeatable/manufacturable.

Option 1 (looks super inefficient):


texts: please help identify the temperature sensor on this PCB

texts:
The PCB is the wireless (outside) sender unit for an inside/outside thermometer. I want to create a temperature probe from this PCB so that I can measure a temperature in a very specific place.
I need help identifying the temperature sensor component on the PCB. I have had no luck pinning it down with freeze spray. Maybe it's the pair of transistors?

(you can view the images at high resolution by doing right-click > view image)

Following on from the accepted answer (thanks!), I tried moving the component out into a probe.

Temperature agrees with my current wired solution.


texts: What is the best battery configuration for a cooling fan and 48000 rpm dc motor, 9volts, about 20 watts of power consumed. Short run cycles approximately 30 sec per cycle. I need  maximum performance for each cycle and with the total number of cycles equal to 30.  There is also a weight constraint of under 1 pound for the battery pack. I'm trying to decide if 6 1.5 volt AA's are sufficient in series or would another configuration work better. My first Post so be easy on me if this question is not suitable for this forum.


texts: Reflow Soldering QFNs with Thermal Vias and Filled Vias in EAGLE

texts:
I'm  trying to solder a 4x4mm QFN IC using the method outlined here
The thermal pad is connected to bottom ground plane with thermal vias. The ground plane is not covered with soldermask because I'm gonna attach a heatsink below the IC.

The problem is as soon as I apply the heat, all the solder drains to bottom plane via the holes and spreads into the ground plane. So IC does not stick.

Then,

Any methods to somehow fill the vias with thermal conductive material?
How do you do filled vias in EAGLE CAD (or do you?) (for next version of the board)
Or any other better advice?


texts: STM32G4x1 ADC Interrupt/flag when a certain value is encountered?

texts: I am brand new with the STM32 and MCU in general. I am reading from an ADC on a continuous mode with the DMA access to memory. I would like to have some sort of "flag" for when a certain ADC value is encountered. The way that I can think of is when a new conversion is finished, interrupt the main cycle and do a manual comparison. Is there a way to do this without using cycles within the main function? Thank you!


texts:
I am a new enthusiast to MOSFETS. I am trying to use a MOSFET to switch on and off a electromagnet that draws 5 amps at 1.2 volts using an Arduino. The circuit I am using has a diode going from the negative to the positive terminal of the electromagnet. The positive terminal of the electromagnet is connected to the positive terminal of the power supply and the negative terminal of the power supply is connected to the ground of the Arduino and the source of the MOSFET, as well as with a 10 kiliohm resistor to pin 13.
Pin 13 is connected to the gate of the MOSFET and the drain of the MOSFET is connected to the negative terminal of the load.

I have been using two different MOSFETs: the Silikron SSF1010 - http://www.silikron.com/upload01//SSF1010%20V2.2.pdf (datasheet), and the IXYS IXTP130N15X4 - https://www.littelfuse.com/~/media/electronics/datasheets/discrete_mosfets/littelfuse_discrete_mosfets_n-channel_ultra_junction_ixt_130n15x4_datasheet.pdf.pdf (datasheet). When the electromagnet is in the switching circuit using the silikron MOSFET, the electromagnet draws 5 amps at 1.2 volts when the MOSFET is on. However, when I use the IXYS MOSFET, the electromagnet only draws 3 amps at 3 volts when the MOSFET is on. I have compared the datasheets, and cannot come up with the reason why. What is the difference between these two MOSFETS? Any help would be greatly appreciated!


texts: How to drive a PMOS with higher Gate than Source voltage?

texts:
I want to switch on/off a sensor which runs at 3.7V using a logic level P-Channel Mosfet. Unfortunately, the microcontroller which drives the P-Channel Gate is powered with a higher voltage (5V) compared to the PMOS Source voltage.
Please check the below circuit diagram. Let's assume, the diode is not in place. I assume current would "leak" from the higher potential (MCU PGIO Pin, when high) to the 3.7V voltage rail.
I added the diode to fix current flowing to the 3.7V rail but I'm unsure, if this is a good practice.
My questions are:
Is the diode enough or are there better practice how to control the PMOS with higher Gate voltage than the source voltage?
Thank you very much!


texts: Mains switch arc - multiple smpsu inrush current

texts:
I am working on a design that consists of a mains power entry module which is a filtered, fused mains switch. This switches the live and neutral conductors to feed 4 switch mode power supplies. Each power supply specifies a cold start inrush current of < 40A at a max input voltage of 264Vac input (UK here). The total load on the mains supply will never exceed 300VA giving a max load current of just over 1A.

I am experiencing some bad arcs across the switch contacts when turning the unit on and off due to the combined inrush of the 4 power supplies. I am new to the subject of contact suppression but I do know the switch will not last without any consideration. I did some reading in to possible solutions and fit an RC snubber (100R 0.1uF 250Vac) across both live and neutral switch contacts. This seemed to solve the issue and the switch no longer arced, however after a lot of persistent use due to testing (~150 on-off cycles in a number of days) the switching arcs have returned even with the suppressors still fitted. I checked for any failure by simply measuring the resistance but that only eliminated the chance of a short circuit failure of the snubber, I'm not sure why they are no longer supressing the contacts.

I looked in to other possible solutions, such as series NTC thermistors, varistors, TVS diodes but am not sure what is best. I think the RC snubber is a good solution but I am not sure how to best calculate the values for R and C that best suit this design. I also have to consider the implications if the RC network fails, resulting in a potential short bypassing the mains switch.

My questions are - should I be trying to limit the inrush current, or focus on suppressing transients caused by the switch contacts?
Also, what is the best solution for my design?

Parts link/ref -

Mains switch - https://www.schurter.com/cns/datasheet/CD21.1501.151

SMPSU 1 (2 of) - http://powersolve.co.uk/sites/default/files/MHP40-100W%20Series.pdf

SMPSU 2 (2 of) - https://www.us.tdk-lambda.com/ftp/Specs/zms100.pdf

RC snubber - Farnell Part# 1438457 Manuf Part# FE-SP-HDR23-100/100


texts: Why doesn't the number of poles affect the angular velocity of a DC motor?

texts:
Angular velocity "\$ω\$" of a DC motor is: \$ω = (2\times π \times n) / 60\$
Where "\$n\$" is RPM.
And not \$ω = (2 \times π \times n \times p) / (60)\$ like in synchronous motors, where "\$p\$" is the number of pole pairs.
I know that the angular velocity of the DC motor doesn't depend on the number of pole pairs, but I don't understand why.


texts: Need help understanding external power on Arduino

texts: I have an Arduino microcontroller. I wanted to control a few servos for an example project but I soon found out the Arduino can't give it enough power. I don't understand how to power something externally but still use the Arduino to control it.


texts:
The I2C communications bus uses 7-bit or 10-bit addressing to address slave devices. Taking the more common 7-bit addresses, each packet sent on the bus by the master starts with an 7-bit address followed by a 1-bit read or write indicator (\$\text{R}/\overline{\text{W}}\$).

Most datasheets only give the I2C address for their device either in binary notation or as bits on timing diagrams (with notes for configurable address bits), which are both unambiguous as they either display seven or eight bits so you can tell if the \$\text{R}/\overline{\text{W}}\$ bit is included. This seems to follow the official NXP I2C specification.

The problem comes when trying to write down the address in hex. Different sources convert the address in different ways:

Convert the 7-bit address to a hexadecimal value in the range 0x00 to 0x7F

0b101 0011 becomes 0x53
Examples Robot Electronics I2C tutorial, Linux i2cdetect tool, STM32 CPAL library, Arduino Wire library

Include the \$\text{R}/\overline{\text{W}}\$ bit as the LSB and give two addresses, one for reading and one for writing in the range 0x00 to 0xFF

0b101 0011 becomes 0xA6 for writing and 0xA7 for reading
Sometimes only the write address (e.g. 0xA6) is given
Examples: 8051 Project tutorial, STM32 HAL library (example of confusion), Microchip PIC code examples (CE119), Saleae Logic protocol analyser

These two options are not always distinguishable.

Clearly using binary notation is better as it gives you an unambiguous address, however this is not always possible. One notable case is on C/C++ where there is not a particularly standard way of writing binary numbers. This leads to the problem I'm having where specifying constants for devices in the circuit is ambiguous.

So in choosing a standard for our schematics, documentation and code (C++) we have to pick one way or the other. That leads to my question:

Is there a dominant way of displaying an I2C address in hexadecimal notation, or are both used commonly?


texts:
I am thinking of making a solar battery charger for some NiMH batteries but am a bit confused as to how make sense of a solar panels IV curve in the application of battery charging.

1) For a direct connection of the battery to the solar cell, will the solar cell be forced to operate at the voltage of the battery?

2)For charging a battery, will higher currents reduce the charge time?

he maximum power point of the solar panel a point where power is maximum but this does not imply that the current is maximum at that point.

3) So if 1) and 2) are true then why is operation at the maximum power point desirable, if the current is not as high as it could be at the MPP? Wouldn't a battery with a lower voltage charge faster as the solar panel would be forced to operate at a point where the current was higher (left of the MPP)?


texts:
Introduction to the problem
While I'm using my treadmill, the house fuse breaker went down (Shorted). After I lifted up the fuse breaker & tried to use the treadmill, it showed me Err 02.
My steps to figure out the problem
I searched & watched a video on YouTube regards this error, I followed the steps & measured the IGBTs of the treadmill board.
Repair Treadmill Error Code E02 | Control Board Faulty
One of the IGBTs readings are 0.00 (Not 0L) on the multimeter using diode mode test, unlike the other 2 IGBTs that I measured and their reading are between 0.370 & 0.423 volts
My questions
1- Did the shorted IGBT behind the house fuse being shorted or it was the opposite?
2- I found online a IGBT (G40N60 IGBT 600V – 70A), And the one on the board is (G40N60 UFD C13AK), is this a right replacement?
3- What's the best practice to make sure that the problem comes only from this shorted IGBT & there're no more faulty elements? To avoid the new one being shorted too.
P.S: I'm newbie to electronics world.
Thank you in advance.


texts: Wiring diagram for IE58A (Incremental-Encoder)

texts:
I have an incremental-encoder, the cable is torn and I opened it and find 8 wires. I'm now really confused how can I understand what are wires for. I want to replace the encoder with a new one so I have to know what each wire is for?

Type : IE58A
Pin: bn    k0         Pin:rt
Pin:gn     k0 neg     Pin:sw
Pin:gr     +Us=11-27v Pin: bn 0.5
Pin:rs     0Volt      Pin: ws 0.5

6 thin wires are :
   + grey
   + pink
   + orange
   + brown
   + black
   + red

2 thick wire:
   + brown
   + beige


texts: Circuit power issues causing LCD to change brightness when motor operates

texts:
My apologies I'm still getting to grips with the more advanced aspects of electronics, so apologies if this is a stupid question!
I'm building a sensor device with a Raspberry Pi, and have got multiple devices connected to it using a breadboard.
I'm having an issue where depending on how fast and which direction I run the connected motor, the brightness/contrast of the connected LCD also changes.
They are both connected to the 5V rail, and being powered off a HW-131 breadboard power module, rather than the Pi.
Here is a link to the video of the behaviour: https://imgur.com/a/jEqhOgr
The program running on the Pi in the video runs the motor at a couple of different speeds and different directions, that is intended behaviour, that's not because of these issues. It's the LCD's reaction to it that I'm concerned with here
Attached is a circuit diagram of my circuit. Boxed in red is the Motor circuit, and in blue is the LED screen header, it's running over I2C.
The power supply supplying the board can supply 2A, is it the case that my power supply isn't powerful enough, or could it be some sort of backfeeding issue from the motor driver IC onto the 5V rail?
Any ideas would be greatly appreciated, thanks!


texts:
I need some advice:

i want to connect an altera FPGA to a computer by USB interface.
i want to avoid placing an microcontroller in my board..
i want to set a nios II to "talk" to the computer
i only need the fpga/nios to act as slave, never as host
the interface chip , should be inexpensive , low pincount & simple.

i know there is demo board terrasic D2-11 with ISP1362 or CY7C67200 , but this chips are as expensive as using an real stand alone microcontroller.

would it be a good idea to use a USB to spi/uart transceiver , in order to interface my NIOS to a PC?

any chip/topology recommendations?

thanks for the advice...


texts: Determining DC gain of single supply op-amp (no AC component)

texts:
I'm building a homebrew PIC programmer, and want to support devices with varying Vpp voltages, so I'm using the DAC output of a PIC16F1825. But the PIC is supplied with a +5V Vdd, so that's the maximum output of the DAC. I can use an opamp to increase that voltage with an available +12V rail using the following circuit (DAC buffer opamp stage not shown):

simulate this circuit – Schematic created using CircuitLab

What has me mystified is how to determine the voltage gain in this circuit apart from trial and error with R1 and R2 values. Ideally, in this case, I'd like a gain of about 2.5 with signals referenced to ground (the real ground, not a virtual one as is typical in single supply AC amplifiers).

For normal dual-supply AC amps, I have a formula of 1+(R2/R1), but that doesn't seem to be valid here.

So my question is: is there a formula to determine the gain produced with a given R1 and R2 or, conversely, to determine R1 and R2 to produce a given gain?

(I could probably accomplish this with a simple transistor, but since I need the DAC buffer anyway, I have a spare opamp available)


texts: How can the FPGA design induce a system wide reset?

texts:
FPGAs have a reset signal that is spread across through the global routing. If the user logic needs to carry out a system reset for whatever reason, how should this be done?
Can the user logic actually drive the reset signal from itself which is ANDed with the reset coming from outside the FPGA? If so, what will happen with the routing resource usage?
Is there another way e.g induce the FPGA to reconfigure itself somehow like it does just after power-up?


texts: How to solder speaker wires back to pcb (Switch)

texts: I have a Nintendo switch lite with the connector for the speaker broken off. I am looking for the best way to fix this. Is it possible to solder directly to the motherboard? I am just looking to restore the sound in a way that will last.


texts: Derivation of power and energy in a capacitor

texts:
I have two very related questions:

In the derivation of power in a circuit we can do the following:

\$P=\frac{dw}{dt}=\frac{d(QV)}{dt}=Q\frac{dV}{dt}+V\frac{dQ}{dt}\$

and then assuming that \$V\$ is constant:

\$P=V\frac{dQ}{dt}=VI\$

This formula holds in every case (that I can think of) in electronics, but why can we assume V is constant, even if we have an ac signal? Furthermore if we are assuming that V is constant why do we not assume that Q is constant also?

Secondly:
When deriving the equation for energy stored in a capacitor you can work out the work done to move charge from one side plate to the other. But in the act of removing charge from one plate, you will change the potential between the plates, so why can we assume that the potential is constant when moving this charge from one plate to another. (the charge is usually infinitesimal (\$dQ\$) and the energy \$dU=VdQ\$ is then integrated over)


texts: In pn diode, how does an electron flow from p to n during reverse recovery phase

texts:
During forward bias : An electron from the negative terminal of battery enters the conduction band of $n$ side, runs toward the junction, waits for a hole for $\tau$ seconds, when it finds one, it falls into the hole in the valence band of $p$ side, then the electron hops along the $p$ side holes and finally reaches the positive terminal of the battery.

Question1 : Why does the electron in the conduction band fall into the hole in the valence band ? Is it because the valence band has lower energy ? If so, kindly keep this in mind when looking into my second question.

During reverse bias, during recovery phase :  An electron from the negative terminal of battery enters the $p$ side valence band, runs toward the junction, then what ? There are no empty energy states available in the valence band of $n$ side, so it seems the electron must climb up to the conduction band to complete the loop.   ( Note that if we abruptly change from forward bias to reverse, initially, during recovery phase, there exist many diffused electrons on the $p$ side near the junction. )

Question2 : Does the electron in the valence band really climb up to the conduction band at the junction ?


texts: Understanding 'Av' in this equation and finding the number of poles in a DC motor

texts:
I've been going through this document for sensorless positioning of a DC motor. On page 11, the value of the sense resistor is calculated using Eq. 2.1.

What is Av in that equation? Is it the gain of the differential amp? If so, then based on their schematics on page 37 the gain would be 220. Putting these values in the equation you get Rsense to be 2.2mR but they've chosen a 400mR resistor. What am I missing? Also, how do I find the number of poles of the motor (pg 13)?


texts: What does it means that a MCU has support for OpenGL?

texts: I am trying to understand the meaning of when someone says that PowerPC 7410 CPU has support for OpenGL based software. Does it mean that there are any specific instruction in its ISA architecture that are good for running OpenGL based software on it? Or does it mean that its Bus architecture is such that OpenGL can work better with it? Or maybe some other criterion that is specially suitable for OpenGL?


texts: On SN65HVD1780 are external pullup and pulldowns

texts: On transceiver SN65HVD1780 are external pullup and pulldowns required on A,B,DE,RE,D,R lines? The datasheet mentions that the part has internal pullups and pulldowns but it's not clear if external pullups or pulldowns are required.


texts: chessboard pattern data from IR sensor MLX90640

texts:
I'm developing an algorithm using esp32 with MLX90640 IR sensor.

After I read data frames and calculated the temperature, the temperature values see a  strong chessboard-pattern style. See images below (raw temperature data)

Part of measured values:

I marked some obviouslly abnormal points.

And here is my core measuring code :

    int expectFrame = 0;
    int subPagesRead = 0;
    while (true)
    {
        while (subPagesRead < 2) {
            vTaskDelay(250 / portTICK_RATE_MS);
            status = MLX90640_GetFrameData(0x33, mlx90640Frame);
            if (status != expectFrame) {
                continue;
            }
            expectFrame = 1 - expectFrame;
            subPagesRead++;
            float tr = MLX90640_GetTa(mlx90640Frame, &mlx90640) - TA_SHIFT;
            MLX90640_CalculateTo(mlx90640Frame, &mlx90640, emissivity, tr, mlx90640To);
        }
        // output mlx90640To
        memset(mlx90640Frame, 0, sizeof(mlx90640Frame));
        memset(mlx90640To, 0, sizeof(mlx90640To));
        subPagesRead = 0;
    }

Am I measuing in a wrong way? Or any other possible reasons?

(This frame is calculated at 4Hz refresh rate on a esp32 chip)


texts: What advantages does the Darlington pair have over the Sziklai pair?

texts:
With all the free time I've had lately due to current events, I've found myself looking into analog amplifier design and analysis (if it helps provide context, my area of expertise is power electronics, where we try to avoid amplifying modes entirely, preferring fully-off and fully-on), so I've ended up with quite a few questions about them.

The Darlington pair configuration for bipolar transistors has one major, and immediately obvious, flaw: its base-emitter junction voltage is double that of a single bipolar transistor. On the other hand, the Sziklai pair has the same \$V_{BE,on}\$ as a single BJT, and still has the multiplied current gain.

So why do amplifiers seem to prefer Darlington over Sziklai pairs? You can even get Darlington pairs packaged to be used as a single transistor, but I've never seen this for a Sziklai pair. Does the Sziklai pair have some performance disadvantages that a cursory examination would miss, or is it merely that silicon PNP transistors are more expensive than NPN ones of similar characteristics?


texts: Understanding input bias current in operational amplifier

texts:
In order to prevent overvoltages on my arduino voltmeter (more than 20v) I decide to add a protection circuit.

As i show in the image i use a AD8605 precision op-amp for the purpose.
(https://www.mouser.com/datasheet/2/609/AD8605_8606_8608-1716254.pdf)
This op-amp has a maximum offset voltage of 80 micro-volt with Vs=5v
and a typical 80 pico-ampere input bias current with -40 +125 degree celsius.
My question is, as i don't know how to calculate input bias current, how do I know I am not exceeding the limits of the op-amp.
The output of the circuit using ltspice is:

Also simulate this circuit in a reverse polarity scenario getting this output:

What I want to know in this scenario if the op-amp will damage or not.


texts: Calculate how much current is a microcontroller's pin drawing

texts:
I am reading up on microcontrollers and I want to know the current that RA0 is drawing when the switch is open but I think I'am getting it wrong. Also my electronics knowledge is elementary at best.

I=V/R
I=5V/4700Ohm
I=1.06mA (rounded off)

I expected to get something close to 50mA or something because of the table below

I need some help.


texts: Converting a headphone output to line level

texts:
I have a guitar amp that has a headphone output.

I would like to convert this signal to line level so I can use it in a small mixer along with other line level signals to be heard in "in ear" style headphones for a live monitoring setup.

How do I convert headphone level to line level?

(And line level in this case is assumed to be the "consumer" line level, aka "-10db" line level)

Also, I would need to convert the stereo output of the headphones into a mono signal in a reasonable way. I'm happy to just discard the right channel since the guitar amp is mono anyway, but I would be curious to see if there is a way to sum the outputs, for example, for the sake of learning, let's assume that left and right outputs are different signals here.

I'm guessing the solution is relatively simple, likely just a resistor or two.


texts: Verilog output port is high impedance (Z) when driven by a sub module

texts:
I'm writing code for shifting 4-bit using carry flag  for generating  delay using instantiating but when I'm instantiating in top module output of top module temp1 always remain in high impedance state could you just check and tell me where I am doing wrong? In an test bench I am giving win=4'b1100 as an data...

The code follows:

module iir_model(temp1,win,clk);
    input [3:0] win;
    input clk;
    output reg [3:0] temp1;

    delay_4   a1(temp1,win,clk);
endmodule

module delay_4(data_out,data_in,clk);
    input [3:0] data_in;
    input clk;
    output [3:0] data_out;

    reg [3:0] data_out;
    reg [2:0] counter=4'b000;
    reg [3:0] temp;
    reg carry;

    integer i=0;
    always @(posedge clk)
    begin
        i=i+1;
        if(i==1)
            temp=data_in;
        if(i>1)
        begin
            if(counter!=4'b100)
            begin
                carry=temp[0];
                temp=temp>>1'b1;
                temp[3]=carry;
                $monitor ($time," clk=%b,  counter=%b ,temp=%b ,carry=%b,data_out=%b",clk, counter,temp,carry,data_out);
                counter=counter+1;
            end
            data_out=(temp==data_in)?temp:4'b0000;
        end
    end
endmodule


texts: Raspberry Pi Intercom, switch using transistor or relay?

texts:
I am trying to integrate my Raspberry Pi into an existing intercom. The old intercom system is mounted and cannot changed due to rental contract.

Intercom functions:

Ring in when someone pushes the button outside the building for my specific number.
I can press a button to Listen to who is outside
I can press a button to Talk to who is outside
I can press a button to trigger a mechanism that keeps the door lock open for about 6-8 seconds

Back of the intercom:

Intercom schematics: (source)

First I'd like to add a switch controlled from the Raspberry Pi to unlock the door. I would need to use a transistor or relay. However, I am new to electronics and don't really understand how transistors work or what voltages they can handle. I understood the how relays work though.

Measurements

I did some measurements and this is what I came up with:

(1) is ground
(2) is 10.2V measured with (1)
(2) shows only ~6V when measured with ground on the metal casing of the intercom
(3) sends the current from (2) when unlock-door-button is pushed
(x) Tone in
(3) to (2) has a voltage of 10.2V
(3) to (2) drops to ~6V when unlock-door-button is pressed (which lasts for about 6-8 seconds)

Should I use transistor or relay?

Is a transistor better in my case?
If I use a relay, do I need external power?
How do I check if the transistor can handle the current that passes from (2) to (3)?


texts:
I am trying to come up with a circuit that generates a series of clocks, I will need these different clocks on different pins. The circuit must be configurable in terms of frequency and phase shift (see below)

All clocks are synchronized.
The first clock will be on for 1usec and off for 9usec.
The second one will have the same frequency but it will be out of phase by x degrees.
The number 3,4,5,6,7,8,9 are exactly the same but they will all be out of phase with their respective shifts.

I can use my CPU but I will have to change frequencies and phase shifts down the line and I want complete flexibility. Assuming I don't use an FPGA, is there a way to generate these clocks with such flexibility. (The flexibility is design time, not user selectable)


texts: Do two stage common emitter current amplifiers add or multiply?

texts:
So I've seen alot of explanations on two stage voltage amplifiers and how how their gains can be multiplied together. My question is when you are using a two stage common emitter amplifier for current amplification, does the current gain from each stage multiply together or add together?

I am thinking they add together because if their base, emitter, and collector are tied together, their currents must add together to form a linear relation with voltage and power. Could someone verify this?


texts:
I am searching for an unbiased, up-to-date comparison of the eLUA (NodeMCU) and MicroPython on ESP8266.

I can only find very superficial reports/blogs of users trying out one or the other. - All of which lacking entirely of technical details.

The closest thing I could find is this probably hopelessly outdated and hard to understand comparison by the MicroPython project.

I would be interested in the obvious questions:

flash usage
RAM usage of VM after bootup
RAM usage in usual use
execution model (i.e. how are the ESP8266 "tasks" mapped?)
execution performance
ease of extension (i.e. module addition)
anything else that might be relevant

From studying the documentation I believe to have understood the following:

NodeMCU has fairly fine-grained build options that allows building only required modules. This appears to allow working with small flash sizes. For Micropython 512 KB seems to be the absolute lower limit in which case no space for user-defined code remains. Not sure how this compares to NodeMCU.
MicroPython has a built-in WebREPL that is auto-configured by default. NodeMCU seems to have nothing similar built-in.
NodeMCU seems to benefit currently from a larger community, presumably due to it having been around longer.
MicroPython documentation is fairy informal, lacking entirely when it comes to extending the C code. NodeMCU documentation seems to be excellent.


texts: What GPIO i need to define for efr32fg14 I2C communication

texts:
UART and SPI i have defined my ports for input and output as follows,but in I2C we have SDA which iss by directional. How to see using the manual shown bellow what kind of gpio we need to define here?
Thanks.
https://www.silabs.com/documents/public/reference-manuals/efr32xg14-rm.pdf
  GPIO_PinModeSet(gpioPortA, 1, gpioModeInput, 0);
  GPIO_PinModeSet(gpioPortA, 0, gpioModePushPull, 1);


texts: As far as I know, the planar process of making IC, especially CMOS IC, is already a 3D process because a layer is added on top of an existing layer to realize various things (cf. Wikipedia IC Layout). So, in my opinion, an IC is already 3D because there are multiple interconnected vertical layers. Why people coined the terms 3D IC then? What does the planar process IC lack in the three dimensionality that 3D IC fulfills?


texts: Elevation accuracy of dual band RTK GNSS module? (ZED-F9P)

texts:
Does anyone know the accuracy of height given from the ublox F9P dual band GNSS module in RTK mode?  Or any dual band RTK GNSS module in general?

The website says up to 1 cm accuracy but I don't know if that is only for long/lat or for height as well.

website of product:
https://www.u-blox.com/en/product/zed-f9p-module


texts:
I use a frequency converter which has an input of ONE phase 240 volt, 50hz.
This device gives me output from 200-240volt, 0-500hz and THREE phase.

The spindle motor I have needs input of 165 volt, up to 300hz.
This motor is connected in Y-format.

I did make three tranformers and connected them in Y-format. It worked but not good enough and it is very very heavy]2

Can you help me to solv this challange in an easier way? (Maybe without using tranformers)

This will be use in Norway (240v/50hz is standard).


texts: Whats the difference between a battery charger & Transformer to power a 12 V 3 A bilge pump?

texts:
I made a common mistake, identical to an earlier post "Using a 12 V 3 A bilge pump on a 12 V 8.5 A LED power supply".

The pump was 3.8 amp so I purchased a 5amp led transformer, which just worked, but failed under load ie (under water). So I understand the problem of initial toque surge load requiring a higher amp transformer (I Think).

The pump works fine on a car battery, but I need a permanent "plug & play" solution.
I connected my battery charger to the pump, & it also worked fine.
The transformer needs to be on full time so as to automatically empty the sump when water enters.

These are my questions;

1) Why does my 20 year old 4amp 12volt Battery charger (see image) work fine as a power supply for the 3.8amp 12v pump?

2) & can I use the battery charger as a permanent power supply for the pump, ie could it overheat & cause a fire?, as they are not normally left on permanently.

3) As I don't want to waste money buying another unsuitable transformer.
Will a " 40amp DC12V Driver AC 230V Power Supply Transformer for LED Strip Light" see image be a suitable power supply for the 3A 12v pump?

It can get expensive buying a standard transformer, but led transformers & battery chargers etc are mass produced, so they are much cheaper options.

thanks for any input.


texts: What is the failure mode for a power supply being incorrectly set for 110/240v using the switch?

texts:
A recent post on Reddit recounted the story of where someone fried a power supply by flicking the little red switch on the back that switches between 110v and 240v modes.

(The thing between the receptacles)

The story involves loud bangs, sparks, and smoke when toggling that switch.

Why does setting this switch incorrectly result in such a dramatic physical reaction?
What is actually happening to the components in the supply when this is set incorrectly?


texts: What does frequency foldback do in a switching regulator?

texts:
I'm looking into using the LT3759. One of the features that they advertise is frequency foldback.

  Frequency Foldback

  When VOUT is very low during start-up or a short-circuit  fault on the output, the switching regulator must operate  at low duty cycles to maintain the power switch current  within the current limit range, since the inductor current  decay rate is very low during switch off time. The minimum  on-time limitation may prevent the switcher from attaining  a sufficiently low duty cycle at the programmed switching frequency. So, the switch current will keep increasing  through each switch cycle, exceeding the programmed  current limit. To prevent the switch peak currents from  exceeding the programmed value, the LT3759 contains  a frequency foldback function to reduce the switching frequency when the FBX voltage is low (see the Normalized Switching Frequency vs FBX graph in the Typical  Performance Characteristics section). Some frequency foldback waveforms are shown in the  Typical Applications section. The frequency foldback function prevents IL from exceeding the programmed limits because of the minimum on-time.

For the following example application circuit that they include,

they provide a plot of the frequency foldback waveforms.

This seems different from foldback short circuit protection.  But how does frequency foldback work? What would be a good analogy to its process? What would the plot look like without frequency foldback?

I also haven't noticed a frequency foldback feature in other switching regulator datasheets, so how important is this feature?


texts: In a delta generator, will each phase voltage always be shifted 120°?

texts:
I'm confused by all the different phases and angles.
Where I live we have a delta generator (3P3W) 230 V system. I was told that the three voltage phases will always be shifted 120° from each other...
... but won't a reactive load in the household shift these? Or I'm mixing up input and output voltage?


texts:
I'm doing a project with the ATUC256L4U microcontroller, and it will require a USB type A connection. I've never worked with USBs before and the microcontroller datasheet doesn't offer much information on how the hardware should be set up. I'm aware the ATUC256L4U has dedicated USB pins, which I think will handle the necessary pull up resistors, but would the circuit really be as simple as the one below?

I've seen other circuits with protective ICs connected, are these necessary or will the dedicated micro pins handle this?

I'm also not planning on powering the device via the USB, should I still connect the 5V pin to something or just leave it unconnected?


texts: Why are binary signals drawn continuous in time despite being a digital signal

texts:
The conventional definiton of a Digital signal is as follows:
A digital signal is a signal that is discrete in time and quantized in amplitude. Almost all resources (textbooks, online sources,etc) stick to this defintion and gives emphasis to the point that a digital signal is discrete in time.

A binary signal is a  Digital signal.

But according to the defintion, the signal should be discrete in time to be a digital signal. In the plot, a binary signal is drawn as continuous in time. Then how can this be a digital signal according to the defintion.

A digital signal according to the definition should look like this:

Also I read that a digital signal has different meaning/definition in different contexts.
For example the above mention definition is apt in the signal processing context, whereas in digital electronics where the binary signal mention above is used, a digital signal is a signal that takes only discrete amplitude values(ie. it is quantized in amplitude) and it can be continuous or discrete in time.

I am confused that why is the above definiton given a strict emphasis even in digital electronics context usually. Almost everywhere I look in internet and even some teachers give the conventional definition of a digital signal without mentioning the context.

Are my above findings correct?
I would like to know the exact definitions of a digital signal according to different contexts.


texts: Failure Modes for Synchronous Boost Low-Side MOSFET?

texts:
I'm looking for some input on possible failure-modes for the low-side MOSFET in a synchronous BOOST converter. I am using LM5122: https://www.ti.com/lit/ds/symlink/lm5122.pdf
Out of 50 units built, 2 units failed in a similar way, taking out the same 5 or 6 components. My most plausible explanation is that the low-side MOSFET failed first, and the subsequent parts failed as a results. Other parts were the controller IC, and a few parts in the IC's external VCC supply circuit. I think the MOSFET failed drain-to-gate and the rest is history.
So far the following testing has been done:

Check IC's VCC voltage is within acceptable range for all input voltage, and output load conditions ---- Constant 13V across all conditions
Check for excessive drain-source voltage at low-side MOSFET shut-off --- Never observed higher than 50V at the peak, many line/load conditions, 60V rated
Check for excessive gate-source voltage during switching --- Essentially matches VCC voltage @ 13V, 20V rated
Check for excessive dv/dt across drain-source during switching --- 1 to 3V/ns maximum, many line/load conditions, manufacturer states ~10V/ns minimum

Although the details are a little shaky, supposedly the 2 units that failed (during ATE testing), failed while (or shortly after) transitioning the input voltage from 0 - 15V (unit #1) and from 15V - 36V (unit # 2). I've heard of things like low-side MOSFET reverse current failure in synchronous buck converters, but I am not sure if similar scenario is possible in syn. boost. In summary, it seems related to the input voltage transitioning, or some other transitory state, as the steady state operation looks fine, from what I can tell.
Any ideas?
Thanks!


texts: P-Channel Mosfet + Step-up Converter + MPPT Charger

texts:
I am constructing a circuit consisting of five parts:

A 400mAH 3.7V LiPo Supply Battery
A [P-channel MOSFET](DigiKey FDN360PCT-ND)
A 2.5-9v Boost Converter
An [LT3652 Solar Charger IC](Digikey LT3652EMSE#PBF-ND)
A battery identical to 1., which is charged by 4.

The boost converter takes the supply battery voltage, and steps it up to a level that the Solar charger IC can use to charge the second battery. This is to prototype a power sharing apparatus for a modular solar charging system that doesn't use a shared pool of solar cells or switching of the cells.
A short description of the project is this. Each module has a battery, a set of solar cells, a microcontroller, and a step-up converter, and is designed to charge its own battery if sufficient power is coming out of the cells, and/or use its battery to charge a neighbors battery if its neighbor is low on charge. I've used ICs that allow a load in parallel with the charging circuit, and I've tried to set it up to be as agnostic as possible- a board can take in solar power and neighboring battery power simultaneously, and can charge a neighbor and get power from the solar cells simultaneously. However, the cells are never directly connected to a neighbor. If hearing this gives you a look of disbelief, and you think this is really stupid, I would love to talk to you about it. The efficiencies for this process aren't good, but the particular reasons for doing this are something I'm willing to go into a ton of detail with over email, and I'm really and willing to admit are foolhardy.

But the important thing is, the idea works as an experiment. When I directly connect the battery to the boost converter, the solar charger is able to charge the second battery. It's inefficient, but it works.

Enter the P-channel MOSFET. I have it configured above the the boost converter load, such that when the gate is connected to ground, it allows the input battery voltage to flow, theoretically providing an input voltage to the boost converter.

I have verified that, in fact, the voltage between VOUT and ground is 9.1V with and without the MOSFET. Here's a schematic of the circuit:

The problem is the current. When I directly connect the battery to the boost converter, I read a current equal to 0.4A (1C of the battery). When I connect through the mosfet, the measured current from the supply battery drops to < 0.1 A (right now I am reading 0.02A)

I've read and reread Horowitz and Hill and an electronics tutorial on using MOSFETs as switches, and the only conclusion I can come to is that that in the on-state, \$R_{ds}*I{d}\$, is so low that the max current allowed on the V-I graph is way below 0.4. My solution is to find a MOSFET with a higher \$R_{ds}\$, so that the resulting \$V_{ds}\$ produces a higher max current. However, I am having trouble calculating this one, since \$I_d\$ changes with \$V_ds\$. What would be a good

It seems like from the responses that the original MOSFET i linked (NDS356AP) should have worked, so I will attempt to switch it out. This MOSFET is part of my lab inventory, and I accidentally linked it but I also have it on hand. I also found this possible replacement- (DK: ZXM61P02FCT-ND) that seems to have better performance in the regions I'm interested in.

Is my reasoning correct, given the proper MOSFET linked? I am having trouble getting an intuition for what is going on here, but I feel like I'm close. Any thoughts/comments would be greatly appreciated.


texts:
If I have a 1 Gb memory with EDAC for single bit correction for a critical application, what could cause a double bit error in this memory? Provided that the queues never get out of sync which causes writes to memory to become corrupted. What other phenomenon (hardware/software related) do I have to consider to take into account for the probability of a double bit error to occur?

It's for an aircraft application, so thats why I included hardware, where we can have single event upset. I am just looking for a probability number I could come up with to justify using EDAC with SECDED.


texts: Emulate the effect of a lock-in amplifier on a signal with a programming script

texts:
I'm working on a gas emission sensing project in the lab which requires the extraction of a signal in a really noisy environment. The features of interests of my signal are much smaller than the noise components. Literature shows experimental setups for similar purposes using lock-in amplifiers to extract the signal. I have never heard of lock-in amplifiers before and my electronics skills are fairly limited. After a quick search on the Internet, I have realized that lock-in amplifiers might be too bulky for my experimental setup and I was wondering if I could emulate the effect of such amplifiers with a programming script.

Let's say I have a noisy sin signal with know parameters:

Amplitude: 1 V
Offset: 3 V
Frequency: 4 Hz
For this example, noise is generated in the script

Based on what I have read about lock-in amplifiers, I would first have to multiply it by a reference signal of the same frequency to eliminate the effect of everything at a frequency other than 4 Hz. Let's say I take a sin wave, with an amplitude of 1V and a frequency of 4 Hz. The result is the following signal:

The average of the signal array would be 0.5; this value might change slightly depending on the noise. Now if I give any frequency other than 4 Hz to my reference signal, this average would be around 0 which seems to validate the theory.

Then, based on my understanding, the signal would go through a low-pass filter. I have programmed a butterworth filter of 6th order, with a sample rate of 30 Hz and a cutoff frequency of 3 Hz. Please note that I am not sure on how these numbers should be changed based on what I am trying to accomplish.

The resulting signal after the filter looks like this:

Does this make any sense at all in terms of emulating the effect of a lock-in?

Another question I have is with regards to my feature of interests. Let's say the features of interest I am looking to extract, in a perfectly clean signal would look something like this:

Now let's say this signal is completely buried in noise. What would be the best way to extract it and have it as clean as possible? Would a lock-in amplifier do the job?


texts: Parameters to compare microcontrollers for low power consumption?

texts:
How do I select a microcontroller with low power consumption?

-for MSP430 series we can compare using \$\mu\$A/MHz at active state.

Similarly how to compare this with other MCU's like PIC and STM series
i.e. other MCU's provide \$\mu\$A/MHz @ diff speed and have DMIPS for performance
and MSP430 series doesn't provide any DMIPS parameter.

If \$\mu\$A/MHz==\$\mu\$A/MHz for ARM and MSP430 is it good to select ARM, as ARM is 32 bit where as MSP is 16 bit MCU?


texts: Minimize crosstalk using shield/guard trace with capacitor ground

texts:
I'm designing a PCB using this component http://www.ti.com/lit/ds/symlink/afe4403.pdf
And from the datasheet page 90 layout guidelines I found point(2) which says
If the INP, INN lines are required to be routed over a long trace, TI recommends that VCM be used as a shield for the INP, INN lines.
And I got a reference circuit in which they had this

So normally when guard trace is required I put a GND trace with VIAs and double spacing on either side.
My question is, having bypass cap is always a good practice or only useful if the circuit demands?. How to determine a long trace,any rules or standards?.
How to route such trace in PCB, do I've to put the cap close to source or destination end?.
Thanks


texts: I need to know how the resistor (named beta compensation in some books) can be calculated. It's clear that BE of Q6 voltage will drop on (2.2k + 68 Ohm). But what the current will be through 68 Ohm resistor? If there is no 2.2k it's clear that the current will be 0.7V/68 Ohm.