texts: Running 9v battery in parallel with Power Supply

texts:
I am putting a 9v powered circuit into an electric guitar. It will be powered by a 9v power supply through a cable, and also have a backup 9v battery on board the guitar. I am wondering if I could run the power supply and battery simultaneously in parallel, to accomplish 3 main goals:

Although the power supply has filters, it needs to be as ripple-free as absolutely possible, as any ripple will be audible as noise. will the battery help to smooth the power supply's delivery? This is the main goal.
I am hoping the power supply will keep the battery charged, will this be the case?
I want to simplify switching and avoid having to manually switch power supplies.

Thanks

Edit: essentially, I am trying to replicate a car charging system, where the alternator and battery run in parallel - the alternator float charges the battery, while the battery smooths any voltage spikes from the alternator, and if you disconnect the alternator the battery will keep the system running.


texts:
I am trying to simulate a triac with MOC3020 but the MOC3020 does not output to drive the gate. The schematics is shown below:

The waveform follows:

Waveform with updated duty cycle to allow LED to glow(as suggested by @MarkoBuršič)  is attached below:

If you look at V(PLUSE), you would notice that the "LED" of MOC3020 is receiving a trigger pulse with frequency of 100 hz while the output V(D1) only peaks at 8m.

I have tried to drive the TRIAC directly with pulse and it works as expected. The circuit for direct pulse is shown below:

 And its waveform is:

I am not sure why the MOC3020 is not providing the gate voltage in this case. Can someone please point me in the right direction?

The model for MOC3020 which is built in is:

  .SUBCKT MOC3020 1  2  3   4
   * pins          D+ D- MT2 MT1
   .PARAM Itrig=15m
   .PARAM RH1=20k
   .PARAM RH2=20k
   .PARAM RH3=16.7k
   Q2 vb1 vb1p vd1 0 PNP1
   Q1 vb1p vb1 4 0 NPN1
   R3 vb1 4 {RH2}
   D1 d1 2 DL
   VD1 1 d1
   R1 ctrl1 4 1
   C1 ctrl1 4 10
   R2 ctrl1 vb1 {RH1}
   R4 vd1 vb1p {RH3}
   GB1 ctrl1 4 VALUE={-500*I(VD1)*3m/Itrig}
   R6 vd2 vb2 {RH2}
   D3 vd2 3 D1
   Q3 vb2 vb2p 4 0 PNP1
   Q4 vb2p vb2 vd2 0 NPN1
   E1 vd2 N001 ctrl1 4 -1
   R5 N001 vb2 {RH1}
   R7 vb2p 4 {RH3}
   D2 3 vd1 D1
   R34 3 4 100MEG
   .MODEL PNP1 PNP(Is=1e-15 BF=10 Cjc=10p Cje=20p Tf=0.1u Ise=1e-12)
   .MODEL NPN1 NPN(Is=1e-15 BF=10 Cjc=10p Cje=20p Tf=0.1u Ise=1e-12)
   .MODEL D1 D(Is=0.1u Rs=2 CJO=50p)
   .MODEL DL D(Is=1e-20 Rs=5)
   .ENDS


texts:
I'm disabled and am looking to be able to charge my power chair whilst I'm on the go in my vehicle, the problem is that I know what my charger draws and outputs in Volts and Amps, but all inverters' power outputs are in Watts, totally confusing!

The charger is a 110/240V in the wall charger and the output is 24V @ 5Amps. So the question is what size inverter do I need in order to be able to use this charger in my vehicle?

Any help will be gratefully received as my hair is now suffering from so much head scratching..


texts: Screwing power pcb to metal chassis through ground holes

texts:
I am mounting a PCB, which deals with currents up to 5A and essentially switches down 60V to 12V and 5V, on a bicycle frame. I have four holes, one at each corner, that are padded with copper traces to the ground plane. Is it ok to fix the pcb to the frame by screwing the pcb through these holes directly on the metal of the frame or can this lead to problems?
Thank you for your help!


texts: I need a rechargeable battery that can produce about 10 Wh per day. In a day this battery/ies should produce 281 mA for about 15 s, 265 mA for about 30 min, and about 131 mA for the rest of the day. How should I go about deciding what battery to choose for this? This battery will be charged with a generator and a solar panel, but for the sake of this question I'd like to assume that these sources are capable of charging up the battery.


texts: how to twin-t notch filter topology single supply opamp

texts:
i designed for twin-t for 50 Hz and BW=2

I have to use single supply opamp but i cant get it single supply opamp thing ...

Can anyone tell me which node i have to do ground , which node i have to do Vcc/2?

-------------------------UPDATED------------------------

i changed Vee to GND and GND to Vcc/2,
this is the result maybe i miss understand something but like i said i really dont get single opamp design.

maybe it is not that clear but it's starts from -15dB.Why is it starts from 0db like previously. You can see circuit at up , my design is perfectly working. Like i said maybe i did something wrong at single supply design

Can someone tell me more spesific which part i have to edit for work perfectly before?

------LAST UPDATED------ (SOLUTION)

i think -15 dB thing, because of cap. Resistor and Cap make filter and this affect all system. Finally, I deleted from there and i added Vcc/2 at input , it's work without problem. There is only offset problem. Output voltage has 2.5V dc offset. Maybe it's come from single opamp topology i dont know...

Anyway this is circuit

Transient Analysis

AC Analysis


texts: Build a nearly 50% duty cycle, adjustable oscillator using D-FF

texts:
Starting from an example circuit, I'd like to simulate and physically realize a D-FF circuit that generates a 50% duty-cycle clock.

Scope of this:

Clock generator for a test circuit
Out 0-5v

I don't have particular restrictions on the output clock:

45-55% duty cycle it's ok
Freq. imprecision of 5-10% it's also ok

I'd like to regulate the output frequency between 100kHz and 400kHz and between 10-400Hz , maybe with a switch that adds an additional resistor.  For now I've added just a potentiometer to regulate the frequency.

Here's an example circuit simulation on Falstad

This circuit doesn't act correctly. Seems to glitch and frequency regulation is not always correct.

My question is:

Starting from this circuit, is it possible to design a reliable functional oscillator (and how?) Or is it completely wrong?


texts: Interfacing Arduino for variable power supply

texts:
I'm a mechanical engineering student with no knowledge on Arduino microcontroller. I am currently working on a project of using Artificial Neural Network in a hybrid solar heating system. The hybrid solar heating system consists of solar flat plate collector for absorbing solar thermal energy and a secondary heater from an electrical supply (immersion heater). I intend using a forecast model to predict the ambient temperature of the surroundings and calculating the corresponding temperature obtainable from a given quantity of liquid using energy balace equations from the solar collector. Different temperature ranges would need different amount of power supply from the electrical heater to obtain a particular water temperature (I'm aware an exact temperature can't be obtained, so maybe +/- 3 degrees difference).

The difficulty I face is how to use Arduino to interface the electrical heater to regulate the amount of heating depending on the predicted temperature from the Artificial Neural Network (i.e if the flat plate solar collector is only able to attain 35 degrees so I'll be needing an additional 10 degrees from the electrical heater to attain a target 45 degrees temperature which is the desired temperature). So how do I set up the arduino interface to supply an additional 420000 joules of electrical energy to get the 10 degrees temperature rise in span of 30 minutes. How can this regulation be done on a 220v 600W immersion heater to produce 420,000 joules in 30 minutes. The 420,000 joules isn't a fixed value, it could change depending on the predicted temperature.

I'd appreciate an explanation that could help me achieve this. A circuit diagram, Arduino code would go a long way in helping.


texts: How a battery is being charged and used as the same time?

texts: this is very interesting question to me that why batteries can be charged while being used as the same time? I designed a buck converter that charges a battery from a solar panel but and when I want to use the battery I would enable a relay that will cut the power off to the battery so I can use it. but using a battery while being charged is possible. What are the principles in this case and would the battery be damaged if being used and charged at the same time?


texts: Help identifying this circuit and understanding how it works

texts:
So I'm hoping to make a few modifications to my computer case and have found that a number of the LED elements have an associated circuit to them.

I want to be able to understand what I'm doing and not damage the existing components and am looking for some help in identifying and reverse engineering the existing circuitry.

The board has 4 input pins and 2 outputs.

5V in and 1.7 - 2.1v out to power a red LED.

The resistors read '103' which seem to be 10KΩ resistors.

It appears there is an optocoupler (PC817)

Finally some sort of transistor - probably BJT, but I've no understanding how they work and originally thought it to be a MOSFET.

I have attempted to breakdown the circuit as best I can, but can't imagine that it's correct.

I'd like to make a DIY version of this circuit in order to test my modifications without damaging the original, so any help would be amazing!

Thanks

Update 1:

So, I've tried my best to make some sense of this and come up with this very simple schematic, but it lacks the transistor element. I just can't logically work out where it goes. What effect would the lack of the transistor (MOSFET or BJT) have versus the original circuit.


texts: What does 'Forward Isolation vs. Frequency' curve in Op Amp Datasheet mean?

texts: I am looking at this ADA4806 datasheet. The specific curve I am looking at it as below. I dont understand what is 'ISOLATION (dB)' on the Y-axis. What is it? What does this curve mean?


texts: Generally I see efficiency related to the lumens per watt, but what is the actual typical efficiency of LEDs in terms of electrical energy in to optical energy out? What sort of conversions apply?


texts:
I am working on a project where I have a current source (analog output from a PLC) controlling a VFD. Based on the position of the dipswitch, the VFD will accept either a current or voltage input. The dipswitch is set to voltage by default, so I used a 500 ohm resistor to convert the 4 - 20mA signal into 2 - 10V. Very straightforward.

Now, what if I set the dipswitch to current and try to control the VFD with voltage, say with a potentiometer? But I just can't seem to build a circuit to convert the voltage into current.


texts: Could someone please give me some hints/point me in the right direction as to how to find Vout for the circuit below


texts:
I'm still a noob to this stuff, and I've run into a problem I can not explain, or understand. I will need help translating / editing this into a real question for you all, so please bear with me.

ASSUME all else is connected properly (pin 1,2,8,9,15...)

See pictures below, this is a simplified version of the whole - the difference is the resistor.

This is a shift-in register (SN74HC165N) that I am using for a joystick controller via an Arduino Leonardo.

With the resistor (top picture) everything works fine, but I can not see how the bottom picture does not work.

How would this look in a circuit diagram? Is there a free automatic breadboard to diagram app out there? Perhaps that would help me understand what is happening.


texts: How to relate the sampling frequency to the measurement error for this kind of pulse period measurements?

texts:
I sample a zero to 400Hz varying pulse train at 4kHz and post-process this pulse train data by MATLAB to obtain each single pulse's period. So for instance below represents a 0 to 6V pulse. The green line is the mid point 3V. So in MATLAB I find the first sample point which crosses up the mid voltage green line and the consecutive sample point which crosses up the green line. These points are shown in red dots. So the time distance between these two red dots gives me the period of that particular pulse. That is how I calculate each pulse period from the logged data.

My question is how can I estimate the error due to sampling rate? Imagine The pulse is 400Hz and sampling rate is 4kHz; and if I increase the pulse sampling rate up to 8kHz how does the accuracy change?

And if I measure and know the actual rise time of the pulse as 2μs, how can I relate the sampling frequency I will use to the pulse period measurement accuracy?


texts: Is it ok to place 220V AC traces on my Arduino PCB?

texts:
I want to control an AC 220V relay with my Arduino Nano, and I want to place everything on one PCB. I worry about 220V tracks, their width is 2mm - is it enough for 220V? Can this create electrical interference to signal (5V) tracks placed nearby?

UPD:

AC 220 OUT will be connected to several LED lamps, nothing special
Yes, I will add flyback diode to this project, but it's still working without it


texts:
The NeverWet superhydrophobic spray is becoming available to consumers.

Are materials like this suitable for protecting circuit boards that may be exposed to water?

http://lancasteronline.com/article/local/861483_Magical-NeverWet-arrives-in-stores.html


texts: Why does current continue flowing in a circuit?

texts:
Sorry for the amateur question, but I'm having trouble understanding this phenomenon.
In a closed circuit, electron current flows from the negative terminal of a battery to the positive terminal.
But why does the current continue flowing? Shouldn't it reach equilibrium once all the electrons have been transferred to the positive side?


texts: Altium Designer: panelization with test tracks

texts:
I have a board which I want to place in a panel. I can do it with Place -> Embedded Board Array/Panelize. Easy!

After that I was intended to place additional wiring and connectors on the panel (outside the multiplied boards). This wiring tracks should brake when the boards goes off the panel.

This is what I have in 3D view for now:

As you can see - the tracks should go outside the board edge. The narrower tracks on the bottom are what I tried to draw on the panel But I had to aim blindly! Look what I have in 2D:

As you can see - no tracks at all! It looks like the boards on the panel is not a board anymore - it is a kind of uneditable object.

In the Altium's documentation:

  but it is not advisable to place any other objects that would
  represent the actual physical design

Taken from this page: Embedded Board Array

So it looks like I'm trying to use the tool in the way it is not intended to be used at all.

It's time for QUESTIONS:

Am I able to see tracks in 2D view of the panel?
Is there any tools in Altium to do this out-of-the-board wiring in a way to reduce human error probability (whis is high if I'd place tracks in PCB without a schematic representations and without DRC control)?
What will happen with the tracks after the FR4 bridge under them would break? Probably I should place V-grove on the opposite side of the panel, should I?


texts:
Suppose to have a I2C device like Sensirion sht21, the datasheet says that the sensor supports both hold master read mode and no hold master read mode.
In addition to that, suppose that the library that reads the devices supports both reading mode.
And that in the I2C bus there is the only one sensor.
Using "long" distances (5/10m) I've seen that using no hold master mode, the MCU (ATMEGA328P) gave me many reading errors, switching to hold master mode, everything works as expected, no issues at all.
How, and why, using hold master mode I'm seeing that?


texts:
While trying to understand CMOS Logic on Wikipedia for class, I came upon this paragraph which I can't quite wrap my head around on the duality of CMOS:

"An important characteristic of a CMOS circuit is the duality that exists between its PMOS transistors and NMOS transistors. A CMOS circuit is created to allow a path always to exist from the output to either the power source or ground. To accomplish this, the set of all paths to the voltage source must be the complement of the set of all paths to ground. This can be easily accomplished by defining one in terms of the NOT of the other. Due to the De Morgan's laws based logic, the PMOS transistors in parallel have corresponding NMOS transistors in series while the PMOS transistors in series have corresponding NMOS transistors in parallel."

Specifically, what does it mean that "All paths to he voltage source must be the complement of those to the ground"?

And how is this accomplished by defining one in terms of the NOT of the other?

Any explanation would be greatly appreciated, and if you can provide a simple example of this even better.


texts: Can LED Power Supply accept different gauge wires at the same time?

texts:
We have under cabinet lighting with this:
It's in the middle of the kitchen on strip of under cabinet lighting goes to the left and one to to the right, black splices together with the black and red with the red and they going into that Armacost. We've had for 8 years, and now want to add an additional led strip. The previous brand is no longer sold, but this will be spec wise all the same except for the gauge of the wire coming out. The gauge would be 18. Vs the existing ones that has a 16 or 14 gauge it looks like. Looks ever so slightly bigger than 16 guage so assuming 14 guage.
Can we simply splice in this additional 18 guage red and black into the Aramcost? So the armacost red hole would have the 2 existing 14 gauge wires in it and now also a 18? And the black hole would have the 2 existing 14 gauge wires in it and now also a 18?
Or would that cause any potential issues?
Ideally they would all be the same. But replacing all the existing wire would not be possible at this time. Getting a new third light strip that's the same guage would be seemingly easier, but to find one that is 24v, a certain light temp, a certain wattage, and many other specs to match the others, greatly limited our options so this one is perfect other than the guage.


texts: What are the general steps used in creating a ASIC?

texts:
I'm following a discussion board that discusses an ASIC chip they are building, and they are using terms that I'm unfamilliar with.  So far I've gathered

Once a logic design is tested on an FPGA it can be ported to an ASIC with relative ease.
The ASIC is created on a Wafer of ~1000 chips
That wafer is chopped up into smaller chips called "dicing"
"bumping"
Packaging:  (not sure what this means:  "Aligning the substrates to the fiduciary marks")

As you can infer, I'm a little confused and overwhelmed by the process, but I want to get a handle on what is required and what the end to end process looks like.

Where can I find a detailed list of what happens after I test my FPGA logic and am ready to create several thousand ASICs based on that design?


texts: Should a diode and/or transistor be used with an automotive (Bosch style) relay for accessory power?

texts:
I am a total beginner with electronics, so I apologize if this question has been answered already, I find similar questions but they seem to always be some variant and not quite what I am seeking, so I am asking here..
My automobile has power ports (cigarette lighter) that is always on.  If I forget to unplug my dashcam I have a dead battery in a couple of days.  To avoid this I would like to add a relay and tap into the accessory position circuit.  Seems pretty straight forward, but then I see a bunch of videos on the importance of diodes due to kickback voltage as the magnetic field on the coil collapses which could cause a problem with the trigger circuit.  When looking at the image below we see a manual switch activates the relay...

... but my automobile has something called "Retained Accessory Power" (A.K.A., RAP) which is what I will attempt to tap into.  My concern is that a voltage spike on this RAP circuit could be problematic. So I am seriously considering using a diode.  Then when I investigate all the circuits I find describing diodes includes the use of a transistor too.  Question:  Should I use a diode?  Should I use a transistor?  If so, what kind/size?  Using this image as an example, how would the diode and/or transistor be wired to protect the trigger circuit?


texts:
here is the question.

As the hints states, we assume it is in Active Mode which means V(EB)=0.7
also, it is given that B=100, therefore, since Ic=B*Ib , gives us Ic=100*Ib
now, I thought it is a good idea to find the relationship between Ie and Ib, so I can apply kvl and substitute one to another so I can come up with one one unknown not two.
Here is what I did
Ic=(BIe)/(B+1)=Ie/101
now I am stuck and I cannot apply KVL from VEE because Vb is unknown, and I come up with two unknowns.
any ideas or suggestions?  I know I have to find Vb first but how?


texts:
I've got an ATMega88A configured to run on internal 8MHz clock:

lfuse = 0xE2
hfuse = 0xDF
efuse = 0x01
F_CPU defined as 8000000

This in confirmed in the 'real world' by blinking an LED with _delay_ms(1000). It's ~1sec, not 8 sec or 1/8 sec.

I've attempted to set the SPI to run at Fosc/2 by setting only SPI2X to 1. (SPR1, SPR0 initialize and should stay 0.) This should result in a SPI speed of 4MHz.

I've set the timer to a 256x prescale.

I'm attempting to send 5000 bytes over SPI. (There's no device connected, just shifting bits out the port.) The timer is zeroed before the transmission and then the value is displayed as LEDs after the transmission.

To send one bit over a 4MHz SPI should take 1/4000000 = 250ns, one byte 8*250ns = 2us, 5000 byte 2us*5000 = 10ms.

However, from my timer: system clock is 8MHz so period is 1/8000000 = 125ns, timer pre-scaler of 256 mean timer tick of 125ns*256 = 32us LEDs show binary of 176 so loop time is 32us*176 = 5.632ms.

How is actual faster than theory?

The kicker? Commenting SPSR = (1 << SPI2X); has no effect on the value displayed in the timer LEDs.

Sample code:

#include <avr/io.h>
#include <util/delay.h>

#define set_output(portdir,pin) portdir |= (1<<pin)

void init() {
    // Set MOSI, SCK, SS as Output
    set_output(DDRB, DDB5);
    set_output(DDRB, DDB3);
    set_output(DDRB, DDB2);
    // Enable SPI, Set as Master, Set CPOL & CPHA to 1 (SPI mode 3)
    SPCR = (1 << SPE) | (1 << MSTR) | (1 << CPOL) | (1 << CPHA);
    SPSR = (1 << SPI2X); // Enable SPI clock doubler
    DDRD = 0xff; // Set PORTD as output
    TCCR1B |= (1 << CS12); // Setup Timer with 256 prescaling
}

int main(void) {
    unsigned int i;
    init();
    TCNT1 = 0; // Zero the timer
    for (i = 0; i < 5000; i++) {
        SPDR = 0; // Load data into the SPI data reg
        while (!(SPSR) & (1 << SPIF)); // Wait until transmission complete
    }
    PORTD = (unsigned char) TCNT1; // Display the timer on PORTD
    for (;;) {}
    return 0;
}

Some problems I've tested:

TCNT1 (16 bits) could be overflowing PORTD (8 bits)? Nope, looping
less iterations reduces the timer value proportionally. (5000 loops = 175 ticks; 1000
loops = 35 ticks)
SPI2X isn't being successfully set? Nope, after the loop if (SPSR & (1<<SPI2X))
returns true.
SPI2X must be set before enabling SPI? Nope, setting it first has no
effect.
No change between optimizations -O3 and -Os, but large increase in
timer value for -O0.
Writing some other value to SPDR has no effect.

Am I going insane?

EDIT: The portion of code in error as answered below was carelessly copied my me without verification from here.


texts:
I've read some very good answers on this subject in questions such as this one and also here.

I'm just a hobbyist designing a very simple PCB, however I still have a few questions about how best to layout the decoupling capacitors on my PCB. It's primarily for WS2811 chips which are LED drivers. I'm using 0805 sized capacitors as I'm not short of space. I could even put the caps on the underside of the board if necessary.

Currently my design stands at this:

The top layer is VCC and the bottom layer is GND. The VCC and GND pins are on different sides of the chip (U1). Currently I've run the data signal (maximum 2MHz) to layer 2 and back. This probably isn't the best way to do it?

Is it even necessary for the GND of the decoupling capacitor to be connected to the same via as the GND of the chip?


texts: How to protect a GPIO pin with a long input wire from transients?

texts:
I am building a custom doorbell system that will support multiple doorbell buttons and annunciators. I am using an Adafruit Feather and a couple of FeatherWings for each unit. The project can be viewed here: https://hackaday.io/project/176143-iot-doorbell-system.
One unit will be the "master" and the doorbell buttons will be connected to it. My concern is possible transients on these relatively long lines resulting in either spurious "rings" or damage to the GPIO pins.
Would shielded, twisted pair (aka CAT-5), be a good solution here?


texts:
Using Eagle 7.6.

I have a part in a TO-5 can. The can needs to mount flush to the PCB, and I'm concerned that the copper on the top side of the standard thru-hole pads might contact the case. For various reasons can't put an insulator between the part & PCB - the part MUST be hard against the PCB.

I could make the pad's diameter really small, which would help the top side, but would provide no real estate for soldering on the bottom. So what I really want is a "single sided" pad - essentially a non-plated hole with a solder pad on the bottom side and bare board on the top.

Any suggestions as to how to best create this?

My thought was to make a zero-width (ie. filled) circle on the bottom (or pads) layer, put a slightly larger bStop filled circle on top of that, then place a 0.025" hole in the center of it all.

Any thoughts/suggestions/opinions would be appreciated,
-Dave


texts: Why N-channel MOSFETs are better than P-channel MOSFETs?

texts: Besides the reason that electron mobility is higher than hole mobility, what are the other reasons of preferring an N-channel over a P-channel MOSFET?


texts: How do I build a computer with a Z80 microprocessor?

texts: I've got the chip, so how would I add: a clock, RAM, hard drive (maybe EEPROM?), a screen (LCD graphical screen?), input method (keyboard, mouse) ?


texts: Transfer function with separate time delays in each term

texts:
We've been given the problem below for our current assignment

As far as I can recall, I have never seen a transfer function with time units in the function itself, added onto each separate term. I have a good idea on how to handle the delay t_d=25ns, but I have no idea how to handle the delays on each term.

One idea I have had, is noticing the that the term t_d=25ns would imply that we need to find the response at t=25ns. As all other terms have delays in the range of microseconds to seconds, I thought that perhaps this would imply that these signals may not yet have "come into effect", leading to the only term being 100*10^3 s. But this seems like an improper transfer function, and Maple's DynamicSystems package won't accept it.

The title of the problem leads to me thinking that the terms and their delays will affect the phase of the transfer function - but the seconds are causing me so much confusion, that I don't know what to keep and what to leave out, when trying to figure out my response.


texts: Why and when are development boards needed?

texts:
To get started with embedded system development, is it enough to have an IDE like MPLAB?

Or, do I also need a development board?

Can't we just program micro-controller logics on our PCs and test the programs in IDEs?

When, at our learning point, do we need development boards like EasyPIC v 7?


texts:
I've was trying all afternoon yesterday to get some data out of my LSM303DLHC using an STM32L152 Nucleo board.

Finally I got all the I2C stuff down, managed to set some registers, verify their contents, etc. so I turned my attention to the data coming out.

No matter what I do it seems, the data is stuck at the same values. When I power cycle the sensor I get changes in the magnetometer values, but then they stay the same until I cycle it again. The outputs from the 3 accelerometer axes are always zero.

I've done a read of the 'block update' register and confirmed the IC it set to do continuous updates.

I have verified on a scope that what I'm receiving is correct to the protocol.

I'm using this breakout board: http://www.aliexpress.com/item/1-pcs-GY-511-LSM303DLHC-Module-E-Compass-3-Axis-Accelerometer-3-Axis-Magnetometer-Module-Sensor/1956617486.html

Any idea anyone? What am I doing wrong here?

#include "mbed.h"

#define ACC_ADDR 0x32
#define MAG_ADDR 0x3C

// ACC registers //
#define CTRL_REG1_A 0x20

#define ACC_X_L 0x28
#define ACC_X_H 0x29
#define ACC_Z_L 0x2C
#define ACC_Z_H 0x2D

// MAG registers //

#define CRA_REG_M 0x00

#define MAG_X_H 0x03
#define MAG_X_L 0x04

#define MAG_TEMP_H 0x31
#define MAG_TEMP_L 0x32

//------------------------------------
// Hyperterminal configuration
// 9600 bauds, 8-bit data, no parity
//------------------------------------

Serial pc(SERIAL_TX, SERIAL_RX);

DigitalOut led(LED1);
InterruptIn btn(USER_BUTTON);
I2C i2c(PB_9, PB_8);

int main()
{

    char data_write[2];
    char data_read[6] = {0,0};

    /* Turn on temp sensor */
    data_write[0] = CRA_REG_M ;
    data_write[1] = 0x90;
    int status = i2c.write(MAG_ADDR, data_write, 2, 0);
    if (status != 0) { // Error
        while (1) {
            led = !led;
            wait(0.2);
        }
    }

    int i = 0;
    int bytes = 6;
    int j;

    while (1) {

        // Read acceleromter data registers
        data_write[0] = ACC_X_L;
        i2c.write(ACC_ADDR, data_write, 1, 1); // no stop
        i2c.read(ACC_ADDR, data_read, bytes, 0);

        printf("\f");
        // Display result
        for(j=0;j<bytes;j++){
            printf("d: %x\n", data_read[j]);
        }
        printf("---- (%d)", i++);

        led = 1;

        wait(0.1);

    }

}


texts: Using Jumpers wires in an Electronic design

texts:
I am working on a design, but still in the prototype stage. In any case, I am using a straight Vero board and hence quite a lot of Jumper cables are involved even to its bearest minimum. I want to know the effect of the Jumpers when they are much? Actually my design is not actually behaving well as it ought to, so I am kind of thinking it my be as a result of this. It involves using MAx232 to transmit data's between a GSM module and microcontroller.

And if there is possible an effect of jumpers, then how can I reduce it to a bearable minimum.

Thanks.


texts: I have noticed that a lot of RF IC's use differential input/outputs, is this "just" to cancel common-mode noise on the lines (in the circuit), or is there another reason for this?


texts: Power supply and pcb connections to ground, earth

texts:
I am planning a pcb which is powered by two switching power supplies

LRS-150F-5 (230 V/AC to 5 V/DC)
LRS-150F-12 (230 V/AC to 12 V/DC)
.

The power supplies are mounted in their own metal box and the pcb is mounted in its own metal box. In the lower sketch you can see the layout once more. My question now is whether I should connect the metal box of the pcb and/or the switching power supplies with earth (FG) and/or ground (V-)? The metal box of the switching power supplies is already connected to earth (FG) indirectly over the mounting screws. What would be a reasonable connection when it comes to safety and EMC?

Furthermore I looked into the switching power supply datasheet and found that the junction is connected to ground (V-) via a capacitor. Could someone explain me whats the reason for that?


texts:
I have 16 meters of WS2812B LED Strips similar to the ones on adafruit. The strips have 60 LED/s per meter and run on 5 volts. They come in 4 meter reels.

I know how i want to control them but i am unsure about how to hook them up safely and so that they draw enough power. I know that i cannot just hook up a power supply to one end and expect the entire 16 meters to be powered. I read online that for the non-addressable ones that run on 12volts you need to hook up the power supply in multiple places, is this the same case with the 5Volts?

Also how do i know what kind of power supply i need and how do i hook it up so that all the LEDs are fully powered? Will i need more than one power supply or should one be enough?


texts: Where am I wrong about my calculation of power loss?

texts:
The power loss of circuit is \$16kW\$ when the power factor, PF, is 0.6 lag. Now if I improve the PF from \$0.6\$ lag to \$0.8\$ lag, what is the power loss now?

The solution provide me the formula below

\$P_{L2}=P_{L1}\times \frac{I^2_2}{I^2_1}=P_{L1}\times \frac{(cos\theta_1)^2}{(cos\theta_2)^2}=16\times \frac{0.6^2}{0.8^2}=9kW\$

And I have two thinking about this question, however, I don't know where am I wrong, because the answer are both wrong!

Method 1

If we draw a relation between apparent power and real power

\$\frac{6}{10}=\frac{x}{16k},x=0.6 \times 16k=9.6k VA\$

now if we improve the PF to \$0.8\$,that is \$\frac{8}{10}=\frac{9.6k VA}{y},\$ so \$y=\frac{9.6k VA}{0.8}=12k\$, so the power loss is \$12kW\$ when the PF is 0.8

Method 2

As the question shown,the power loss is 16kW when PF is 0.6, that is, \$IVcos\theta=IV0.6=16k\$,so \$IV=\frac{16k}{0.6}\$

Now the PF become 0.8, that is, power loss\$=IVcos\theta=IV \times 0.8=\frac{16k}{0.6}\times 0.8=16k\times\frac{4}{3}=\frac{64}{3}W\$

Now as we know, the solution of my both thinking are wrong, does anyone know where is my calculation or thinking  wrong?


texts: 300VDC to 24VDC voltage converter - Cheapest implementation

texts:
In an application, 100+, 100W 24V halogen lamps need to be individually controlled and run simultaneously. They stay on for a few seconds at a time and need to have very constant irradiation.

Furthermore, It needs to be as cheap as possible, but have fine control of the lamp with at least in the 0.5% granularity of the maximum power output.

This system is enclosed and is for lab use.

The first attempt was to rectify and filter main (230VAC) and use a DC/DC buck converter to go from 300VDC rectified to 24VDC being controlled by a dsPIC33.

However, I miscalculated the inductor required and the main issue is, with the correct inductor, the Duty cycle of about 8% which at a frequency of 20kHz only leaves very large granularity for the speed of the dsPIC to generate the PWM.

Another option is to have a large (or several) AC/DC supply to go from the main to 25V or so and then a buck on each lamp, but that would increase the cost significantly, about 2-3k$ for the supplies and large currents will have to be handled.

Is there a cheap, more appropriate topology for this need, or is there a way to increase the nominal buck duty cycle without wasting power and having reasonably sized coil ?

EDIT:

Perhaps a possibility would be to have directly 230VAC and regulate the lamp directly with a Triac although the ripple would be too big at 50 (100Hz) so there would need some sort of circuit behind as well.

EDIT 2:

Someone came up with the idea of using lead-acid batteries which would lead to the use of a much smaller power supply and drive the lamp directly in PWM without buck, not sure about EMI and cold start.


texts: Can a diode effectively regulate a supply voltage?

texts:
I have a 6V DC battery that's rated at 2A.
My microcontroller uses 5V supply at about 50 mA.

I've been told I shouldn't worry about the current since the microcontroller will just take what it needs.

My first thought was to just throw a diode in there to drop the voltage but then as I read about it people were saying the voltage drop might fluctuate? My battery is DC so I think that voltage is pretty steady. Shouldn't the voltage drop be steady then?

Also, can resistors be used to drop voltage?


texts: Robot following you; what's the best way?

texts:
I built a human-sized robot that can follow anyone wearing an IR beacon.

It works quite well indoors and it's quite precise, but outdoors it is completely blind due to sunlight infrared.

I have a bunch of XBee I can try to use to triangulate someone wearing an XBee as a beacon but I was wondering: What's the best way to make a robot follow you pretty much in every environment if you aren't more than 10 meters from it?


texts:
I'm trying to design a lighting circuit for an indoor garden, and I'm not understanding things that seem like they're really basic, so I need some help. The schematic I'm referencing is:

I have a 24V input source which I'd like to limit to 20V. LA is a series array of LEDs such that the total voltage drop across the series is ~19.8V. R1 and Z1 are designed to limit the circuit to 20V. The portion of the circuit after that (the area above the "Repeat 14x" label) is a constant-current circuit as adapted from this instructable, and will be repeated a total of 14 times. Each of those will draw approximately 0.02A.

My confusion stems from the presence of RA and ZA, that, in tweak 3 of the constant current instructable, limits the input to the gate of QB to about 5V. Doesn't it also limit the entire circuit to 5V, including the drop across the LED array? RB was calculated to be 27 ohm 1/4 W from the formulas provided in the constant current instructable; do I only need QA, QB, and RB in the circuit, and then connect the gate of QB and collector of QA to the R1/Z1 circuit?

Device value specifics:
R1 - 140 ohm, 1/4 watt resistor
Z1 - 20V 1W zener diode
RA - 100k ohm, 1/4 watt resistor
ZA - 4.7V 500mW zener diode
QA - NPN transistor (Fairchild 2N5088BU)
QB - N-channel MOSFET (Infineon IPP057N06N3 G)
LA - 6x3.2V LED in series (e.g Cree C512A-WNS)
RB - 27 ohm, 1/4 watt resistor


texts: What is the importance of separate power and logic ground (ie a Vss pin) in gate driver

texts:
I have 2 different versions of a high and low side driver; IRS2186 AND IRS2186. I have attached the typical connections, taken from the data sheet (data sheet: https://www.infineon.com/dgdl/irs2186pbf.pdf?fileId=5546d462533600a40153567716c427ed).

IRS21864 has an extra pin Vss which is the logic ground but otherwise the connections are the same (just laid out slightly differently in the diagram). Both drivers should perform the same function so I was wondering what benefit having a separate power and logic ground achieves?


texts: Routing power into power plane (4 layer PCB)

texts:
In a four layer PCB scenario with standard layer stack-up (signal, GND, power, and signal), how do you get power into the power plane?

In my case, there is a voltage regulator sitting on the top layer (SMD) and I need to get power from it into the third layer which is my power plane. Is it enough to put some vias near the output pin of the regulator (or output cap)? It is a mixed digital-analog design. (STM32F4 + some DACs).


texts:
I would like to create a simple Li-Po protection circuit that will prevent a single-cell from going below 3.7V. My circuit needs to have a low current input detector (pref < 5uA).

My attempt at this was to use a Zener diode backwards in order to test if the battery is above the breakdown voltage. Schematic below.

This schematic works in the simulator, but I'm not sure if This is actually a viable approach. What improvements can I make to this approach, and what better (preferably simple) approach is better than this?


texts: Best way to hook up Many analogue sensors

texts:
I started a home project which has become almost impossible i think and its all my own fault!

I planned on using a raspberry pi to monitor around 80 analogue sensors - specifically force resistors. I have since learnt that to use these sensors i need;

1) an analogue input on the raspberry pi - which i dont have
2) i could use an analogue to digitial converter which would then lose any information from the sensor

Step 2 is not desirable because i want to know when a sensor is above a particular value so based on this what are my options

Have I been far to optimistic and should i maybe swap the pi for an arduino or something? Is it ever possible to hook roughly 80 of these up to something so small? Hopefully someone can provide some assitance

Thanks

edit:

The sensor type can be seen below - ideally all i want is to be able to read all 80 sensors and tell when a sensor is over a certain force. I dont need to know the force, just that it has been surpassed.

  This is a force sensitive resistor with a square, 1.75x1.5", sensing
  area. This FSR will vary its resistance depending on how much pressure
  is being applied to the sensing area. The harder the force, the lower
  the resistance. When no pressure is being applied to the FSR its
  resistance will be larger than 1MΩ. This FSR can sense applied force
  anywhere in the range of 100g-10kg. Two pins extend from the bottom of
  the sensor with 0.1" pitch making it bread board friendly. There is a
  peel-and-stick rubber backing on the other side of the sensing area to
  mount the FSR. These sensors are simple to set up and great for
  sensing pressure, but they aren't incredibly accurate. Use them to
  sense if it's being squeezed, but you may not want to use it as a
  scale.

I want to detect when a seat has been sat on, but want to only show something that would be heavier than a bag. Thats why my condition of over a certain limit comes in to it. Ideally the cables connecting the sensors wont be too long, a couple of feet max i guess.


texts:
Idea:

Run a 68000 emulator on a PC, and connect the PC to an existing 68000 system, replacing the CPU with a ribbon cable going to the PC.

I realize the emulation would not be cycle exact, but that is not the goal.

Question: how much would it take in terms of glue logic between the systems, minimum?

I have some crazy ideas:
IDE port on PC is 5 volts. IDE is basically a 16 bit parallel port.
The 68000 has 16 bits data bus. Maybe some latch to keep the 20 bit memory address? Reset flanks could be stored in and read out by emulator?


texts: Breadboard setup for a data acquisition system trigger

texts: Does anyone know what the best way of getting from a variable input of either 110v or 220v and using just a standard breadboard (solder type) and getting down to a 5v output.  Please let me know if I need to be more clear.  This is fairly new to me.


texts: Does Intel pentium 4th generation was made for 10GHz

texts:
Somewhere during browsing on Internet I have seen that

  Intel Pentium 4th generation was made for a high operating clock frequency of around 10GHz, but the researchers can operate it only for a time period of 30sec to 1min because of the vast power dissipation at such high frequency. So they restricted it to around 3 to 4GHz

Is this true. Does the Pentium 4th generation technology was improved later so that it can operate at such a high frequency i.e., technologies having lower power dissipation have come so that we can have a processor at 10GHz

EDIT
Due to the misconception on the question and thinking it as a duplicate(Sorry for my poor English if it is not conveying what I am actually thinking)

What I actually asked is whether the above quote is true i.e, any evidence and if so any research work was done from then in such area...

I knew that clock speed is highly constrained by power dissipation and clock speed almost remained flat in the present decade Ref: http://cpudb.stanford.edu/visualize/clock_frequency

I already gone through the question Maximum clock frequency of microprocessors at the time of posing my question


texts:
I want to make a voltage multiplier to gain a high voltage, I understand that you must input AC for it to work and you get DC out. I also understand that the multiplier is made up of capacitors and diodes.

What I don't understand is how you calculate what size capacitors you use. I have often just seen a value of 10nF; but what does that do, and can you use different value and what effect does it have? Are there any equations for voltage multipliers, even for calculating total output voltage? Say I wanted to make a voltage doubler to start off with; would I use 10nF?


texts:
I have a 3mm copper test sample that is going to get heated up, and I would like to know how hot it is actually getting. Previously, we have just held the thermocouple close to the sample, but we are considering mounting it to the sample to get a more accurate reading. I was told that it is possible to weld an exposed thermocouple to the sample, but I am concerned about making a ground loop.

I guess there are two questions here:

Will a ground loop be created and do I need to be concerned about
metal-on-metal contact with the thermocouple and copper for any
other reasons?
Does anyone have advice on the best way to actually weld the
thermocouple to the test sample?


texts: Whats the principle of a PLL used as demodulator of a FM signal?

texts:
I didnt quite understand te following:

A basic PLL consists of the following parts:

phase detector
low pass filter
VCO

If you input a 1MHz sine the PLL will try to lock on it by controlling the VCO. According to what i've found it's possible to demodulate a FM modulated signal.

Assume:

Input signal for example: (Carrier: 1Mhz sine and signal of 50Khz). you get 2 side-band frequenties with the carrier frequention (0.95Mhz, 1.0Mhz and 1.05Mhz).

I want to demodulate the 50Khz signal from the input signal.

From what i've found a DC signal from the Phase Detector is fed to the VCO to keep the PLL locked to the input frequency. My assumption was (i might be wrong) that when you input a signal with multiple frequency components the PLL keeps "re-locking" and the DC voltage fed to the VCO is the same as the difference of the frequention components of my input signal (so 1.0Mhz - 0.95Mhz = 50Khz).

edit:

Ye, there are some misconceptions in my story. With AM modulation you get the frequency components i was talking about (Dual Side-Band Full Carrier).

With FM modulation you have the following formula:

\$v_c\$ = carrier, \$v_m\$ = modulator

\$v_c = V_c \sin(2 \pi f_c t)\$
\$v_m = V_m \sin(2 \pi f_m t)\$

\$f_c\$ depends on the modulator voltage so \$f_c = f_c + k*v_m\$, where k is a amplifier factor.

the complete formula becomes:

\$v = V_c \sin(2 \pi (f_c + k v_m) t) \rightarrow v = V_c \sin(2 \pi (f_c + k V_m \sin(2 \pi f_m t)) t)\$


texts:
I am trying to meet the compliance/min output voltage of a wide swing current mirror so the output current (10uA) is within .1% or +/- .01uA. I am using Cadence and ami06 nFET's to do so. I am always off by .005~.01uA in either direction. I have spent 2 days adjusting the widths, lengths, and conduction parameter, k' but cannot get the output current pinned under .1% of the input current.

I believe tweaking the threshold voltages (and body effect) is the only thing left to try. Currently, I have all of my bulk terminals connected to ground and all of my hand W/L ratio calculations include the body effect. This brings me to the question at hand - When using BSIM3V3, is connecting the bulk terminal of a MOSFET to it's source terminal the same as ignoring the body effect when deciding W/L ratios on paper? If so I plan to recalculate all of my ratios without the body effect and try the simulation again. Thanks for your help.


texts: How are these hall effect sensors connected?

texts: Trying to understand how to wire the hall effect sensors from a car seat motor. The part # given in the image below seems to be an Allegro device. I can't figure out how to wire these. It seems pin 2 of the sensor is where you'd get the output from. However, according to this schematic, there is no way to access that pin. The Out 1 and 2 as shown in the image would be where you'd connect 5V. I need to provide a way on the driver board to connect these. Should I just provide a 3 pin terminal where you can connect Out 1 and 2 and a 5V supply next to it? Full motor specs are here (caution: massive image) shown here (this is a scaled-down image of the full motor spec which is a massive TIFF file.


texts: Poblems with flashing samd21 xplained pro board

texts:
I'm trying to flash the samd21j18a microchip from Linux but I'am unable to do so. I've compiled toggle Led example from Atmel Framework. I tried to flash it using bossac tool and I received the following error message:

  No device found on ttyACM0

The device /dev/ttyACM0 exists and I tried to run it under superuser to avoid problems with lack of permissions.

When I used the proprietary SAM-BA programmer it got stuck while connecting. I tried to flash it from Atmel Studio on Windows. It worked fine however it required an update of embedded debugger firmware to 2.10 version.
After booting back to Linux and attempting to flash it again I received a different error message. Here is the whole output of bossac:

honza@honza-MS-7823:~/Downloads/BOSSA-1.6.1-arduino$ sudo '/home/honza/Downloads/BOSSA-1.6.1-arduino/bin/bossac' --info --port ttyACM0 --erase --write --verify --reset --debug -U false .pioenvs/samd21_xpro/firmware.bin
Send auto-baud
Set binary mode
readWord(addr=0)=0xfcfc00fc
readWord(addr=0xe000ed00)=0xfce01c
readWord(addr=0x400e0740)=0x1cfcfce0
version()=
chipId=0x1cfcfce0
Unsupported Cortex-M4 architecture
No device found on ttyACM0

And the proprietary SAM-BA programmer also fails on the following message:

  Invalid chip ID

It seems to be returning ID of Cortex M4 based chip even though it's Cortex M0+ based one.

I don't want to use Atmel Studio because I'm used to JetBrains IDEs and Linux environment.

I'm new to electronics and I'm kind of lost.

Thanks in advance


texts: two pnp switch, can't declare voltage inbetween

texts:
I am trying to learn electronics and I am analyzing this circuit.
I was wondering why the voltage inbetween Q5 and Q6 is always about 700mV when Q5 is open. Thanks in advance!


texts: Switch between 2 power supply feeds without device losing power

texts:
I have done a search on here but didn't find the answer (maybe "woods for the trees") but here goes...

A brief 'background' -- In my house, there's a switch by my front door that turns on/off the outside light above the door.  The wiring is obviously cemented in place and has been for 15+ years that I know of... Where the light is, there's a round junction box of sorts, wiring is buried in solid walls etc so, for now at least, re-wiring is NOT an option.  The oddity is that, there is 2 feeds at this point - and they are the opposite of each other.  1 is connected to the exterior light, the other is connected to nothing.  When the Light is ON, the other feed is off, when the light is OFF, the other feed is ON.  I've no idea why!

Anyways, this is the only feasible external power supply point to use for a CCTV camera being fitted (2 actually, Using MotionEyeOS - a Raspberry Pi OS for using a Pi as a CCTV system).

What I had done as a temporary measure, was I wired in 2 sockets, and simply plugged in a 5v USB plug in each.  They then joined via a USB Y cable, and connected to a PowerBank device that is capable of charging whilst simultaneously powering 2 connected devices to a max of 3.1A (1 USB Port is 2.1A, the 2nd is 1A) - and then the Raspberry (x2) were connected to the powerbank.  This worked nicely for some time, but of course, due to the power consumption of the 2x Raspberry's, it's power eventually depletes quicker than it can charge.

This brings me to my question - how can I wire these sockets (is there something I can buy?, or do I need to make a circuit?) so that the power to the Raspberry Pi's is not cut momentarily when turning the light on and off? - In other words, How can I keep the 2x Raspberry Pi's powered when the switch is turned on or off? (and the power switches from one feed to another)

Note: Total power usage would be 5v x 2, and 2.5A max x 2 (So 5v, 5A max)

I realise the power loss would be something like a nano second, but I imagine it still has potential to lead to untold issues!?


texts: What frequencies are usually used/most efficient for coaxial transmission lines/?

texts: I was researching what frequencies are usually used for coaxial Tx. Most sources just says that at low f the length of the line doesn't matter and vice versa. However, I couldn't find a source that indicates the best f are used for transmission lines to transfer power. So what are the best frequency range to use? khz, Ghz ?? And why?


texts: Resistance as a function of base voltage in a transistor

texts:
In this very interesting introductive video https://www.youtube.com/watch?v=CkX8SkTgB0g, I learned that a transistor is basically nothing more than a resistor whose value changes accordingly to what's applied at the Base.

So it should be possible to draw a characteristic curve of a NPN transistor with:

x-axis = voltage applied to Base
y-axis = value of the resistance between Collector and Emitter

Here is what I imagined (Am I totally wrong, only a little bit wrong, or nearly correct?) with my current understanding of a NPN transistor :

I haven't found such a curve, even in the datasheet of the transistor I have (2N3904)  http://www.ece.rice.edu/~jdw/data_sheets/2N3904.pdf

Is it relevant to draw such a curve? Where can I find one for 2N3094?


texts: Handling high pulse current through relay contacts

texts:
I have a circuit similar to the following:

simulate this circuit – Schematic created using CircuitLab

The peak current can get up to ~120A for about half a microsecond.  The SCR will take care of the 'hot' switching -- the relay is just there to configure the load and other components not shown here.

I'm having a difficult time finding any specs on pulse current ratings through relay contacts.  I've had my eye on the Omron G7L-2A-X, which is rated for 25A, but it's hard to cough up ~US$100 for a relay that could turn to smoke with one operation.  Is there a way to determine whether a relay can repeatedly survive such conditions without just buying one and trying it?  Are there rules of thumb to go by?

(I've looked at previous questions here and here, but neither seem to be quite what I'm looking for.)


texts: Is there something like a Single Pole Quad Throw Relay?

texts:
I want to be able to route an analog signal through at least 4 different points. Now I know that I can't use analog multiplexers since the signal (high power) I want isn't within the range they can handle. So is there anything like an electromechanical multiplexer or something? Because a relay is fundamentally an electromechanical switch - usually single pole double throw. So, is there anything like a single pole quad throw version of it (if possible and as far as I have searched, none exist)

I know I can achieve this by using 3 relays in a tree like configuration but is there a more elegant solution or device?

The signal I intend on multiplexing is the commercial power line in India - 230VAC


texts: TPS61097A-33 booster providing lower voltage than input

texts:
I ve been trying to get the TPS61097A-33 working to get the promised 3.3V output voltage. I am using two AAA batteries as input and the circuit current draw is 20mA. I am using 4.7uH inductor and 10uF caps at the input and output as indicated by the datasheet...on connecting batteries I get a lower voltage of around 2.5V at the output when the load is connected and around 3 V when no load...Does anyone have any experience with this ?
link to chip:
https://www.ti.com/product/TPS61097A-33?utm_source=google&utm_medium=cpc&utm_campaign=app-null-null-GPN_EN-cpc-pf-google-eu&utm_content=TPS61097%5B!%5Benter


texts: How does an e-cigarette dry tank protection sensor work?

texts:
E-cigarettes work with a resistance coil which heats liquid into vapor. Some e-cigs have a dry-tank protection, which senses when the coil does not have any liquid to heat, to avoid it getting too hot. My e-cig uses SAE 316L stainless steel resistance coils and is only tuned to protect for that specific type of coil.

How does the dry tank sensor work?


texts: How to load Touchgfx files to external flash

texts:
I have W95Q64 flash memory and STM32F429 custom board. I want to load Touhgfx files to external flash memory. For this purpose, firstly I added below declarations into FLASH.id file as;
SPIFLASH    (r)    : ORIGIN = 0x9000000,   LENGTH = 8M
and
ExtFlashSection :
  {
    *(ExtFlashSection ExtFlashSection.*)
    *(.gnu.linkonce.r.*)
    . = ALIGN(0x4);
  } >SPIFLASH

  FontFlashSection :
  {
    *(FontFlashSection FontFlashSection.*)
    *(.gnu.linkonce.r.*)
    . = ALIGN(0x4);
  } >SPIFLASH

  TextFlashSection :
  {
    *(TextFlashSection TextFlashSection.*)
    *(.gnu.linkonce.r.*)
    . = ALIGN(0x4);
  } >SPIFLASH

after compilation in CubeIde, the memory is created as shown below;

My problem is that I dont know how to download all those files to my board. As far as I know, I need to use external loader in debugger section but there is no convenient option in the tab which is exactly match with my configuration.

it will be appreciated if someone explain what to do additionally and explain all procedures step by step.
Note: I include the library and called W25qxx_Init() in the main block.


texts:
1) Do corners always refer to PVT corners in ASIC design? Or are there any other elements involved in a corner?

2) On what basis are corners named "Slow", "Typical" & "Fast"?

3) What factors govern the number of corners to be considered while designing an ASIC?

Please try to explain the answers to the above questions with an example.


texts: RobotDyn dimmer controlled by ESP 07 only results in flickers

texts:
I use a dimmer module connected to an ESP07 which has Node MCU firmware.

I'm using the Z-C interrupt to skip sinusoidal pulses, however I only obtain flickering instead of dimming. The light is bulb is halogen based so it's dimmable.

Below is the code that I'm using. Do you have any idea what I should investigate?

--The Z-C pin
gpio.mode(2, gpio.INPUT)
--The PWM pin
gpio.mode(5, gpio.OUTPUT)

gpio.write(5, gpio.LOW)
pwm.setup(5, 1000, 0)
pwm.start(5)

counter = 0;

local function zc_callback(level, pulse)

    counter = counter + 1;
    counter = counter % 10;

    if (counter == 0) then
        pwm.setduty(5, 1023)
    else
        pwm.setduty(5, 0)
  end
end

gpio.trig(2, "low", zc_callback)


texts: How to multiply base system clock using .xdc constraints in Vivado

texts: This question may be ridiculously rudimentary but I have been going through Xilinx's available guides and videos tearing my hair out...  my problem is simply this:  I want to use the base 100Mhz clock on my nexys4 DDR board and multiply it by 2.  Can this be simply achieved using the .xdc constraint file?  I have tried using the clocking wizard IP but perhaps I simply don't understand how to instantiate the clock with respect to my source design.  I have attached a few pertinent captures to better explain my issue.  Any help on this would be greatly appreciated.


texts:
I am currently designing a board for a STM32F102 chip which needs to be able to use the USB bus to transfer data while the chip is running. However I also want to be able to program the chip through usb while developing the software.

I want to make sure that while designing the board I wont do anything that makes this impossible later on, so I am asking for some clarification on some things.

First of all in accordance with the USB standard, because the STM32F1 supports full speed usb, I have a pull-up resistor on the D+ line.

Now, in order to boot from the main flash the boot0 pin must be logic 0, so I will connect that to a pull-down resistor on the board. In order to use the included bootloader (which I believe is what I need to program via usb) the boot0 pin must be logic 1 and the boot1 pin (which is a gpio however is an input on reset) should be logic 0.

Assuming I am understanding all of this information correctly, what would be the best way of going about being able to program the chip when a usb cable is plugged in? Can I use the usb V+ and GND to set the logic levels needed on the boot pin? or should I connect those to the boards V+ and GND and use a switch to set the boot pins accordingly?

If there is any other information required I'd be happy to help you understand what I need or am asking for better.


texts: Transistor for 4-20 mA voltage drop resistor connection?

texts: This is for converting a 4-20 mA current loop signal to a voltage. Is it okay to connect the resistor for measuring voltage drop with a transistor to allow for switching between voltage and current measurement mode or is this a bad idea? Usually jumpers are used but I'd like to make it software controllable.


texts:
I'm trying to figure out the input capacitance of a VCO I am looking to use. The datasheet of the device does not specify an input capacitance. However, it does include the following. illustration
Looking at the interface schematic of the Vtune pin, I see two possible figures I could use for input capacitance. One is 5.2pF, the given capacitance of the capacitor in parallel with the Vtune pin. The other is 16-18 pF, given as C; to the right of the schematic. From this drawing, which one of these figures seems more likely to be the input capacitance of the VCO. Here are some more datasheet images for context.


texts: Has anyone been able to get a PICAXE working with the BlinkM? What is the I2C speed?


texts: Altium Hotspot Snap of Pads in Footprint / PCB Library Designer

texts:
I'm trying to create a footprint for a USB receptacle using the drawing of the recommended footprint for that part.

The problem I'm facing is that, as it is common with mechanical drawings, the distances between the edges of pads are specified instead of distances between pad centers. So I'd like the edge or corner of a pad to snap to the grid instead of the center of the pad. I have studied this article, however hotspot or axis snap does not seem to work for simple pads. Is there another workaround?


texts: How does open drain io act as bidirectional

texts: Could someone explain how open drain io acts as bidirectional. Whether it is actually bidirectional or it can act only as input or output at a time.


texts:
I understand that rise/fall time are related to RC charging/discharging waveforms.

What I don't understand is how is the 0% and 100% points chosen? Do they have to be defined beforehand for a signal?

My oscilloscope will automatically find rise/fall time with 10-90 gating like the picture below for an arbitrary input. How does it automatically choose a 100% point if an RC only asymptotically approaches some value? How does it know to avoid rining at the top of the waveform?

Update 1: Request to check Oscope manual.

"The rise time of a signal is the time difference between the crossing of the lower threshold and the crossing of the upper threshold for a
positive- going edge. The X cursor shows the edge being measured."

My confusion is that I never set thresholds. The measurement can be done automatically by just choosing "rise time". Not sure if it just defaults to max and min of what's on screen for 0 and 100%.

My question is more than for just a particular O-scope tho. I'm trying to understand if there is a commonly accepted rigorous definition for this. Even outside an O-scope measurements. If I draw the waveform above, how do you chose the 0 and 100% points?


texts: Ground loop Isolation transformer, alternative?

texts:
Most of those transformers are a bit costly in my region(India). is there any alternative solution that can be employed.

Application in audio amp.

I was thinking maybe use a step-down and step-up transformer, of same ratio, in tandem. Can it work?

Thanks.


texts:
I do not have expertise in electrical engineering, so I may sound completely naive. I am currently trying to back drive a brushed dc motor. I am reading an analog value from two pressure sensors in a voltage divider circuit that tells the motor which direction to go. Ideally, I want zero mechanical impedance and the motor should drive smoothly and change direction swiftly.
For the code, I have taken bits from the code provided by Robojax ("https://www.youtube.com/watch?v=PUL5DZ9TA2o&list=PL0Lbcgzld5acxcoteYK7Ph5EA1f4ShK91&index=17&t=0s") and put it in my sensor reading code. I have got the motor and pressure sensors working but the motor gives jerks when moving and changing directions. I want to smoothen it out. I think my circuitry is alright, maybe changes in the code will be helpful.

Motor>> https://www.aliexpress.com/item/32827922906.html?spm=a2g0s.9042311.0.0.
Motor Driver>> https://www.aliexpress.com/item/32819146048.html?spm=a2g0o.productlist.0.0.aadb5f199FbGJd&algo_pvid=0ff3f02d-e74d-4856-83d5-4b424b6b5173&algo_expid=0ff3f02d-e74d-4856-83d5-4b424b6b5173-0&btsid=0ab6fa8115835324922871163ec5a6&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

code is attached if I am missing out on any info, please let me know.

Thank you.

const int SensorPin = A0;
int SensorVal;
int PreviousSensorVal;
int change;
const int Middle = 511; // adjusts middle value of potential divider - 0 to 1023 is the range
const int Cushion = 10; // adjusts sensitivity higher number means less sensitive

//*************motor part*******************
#define RPWM 3 // define pin 3 for RPWM pin (output)
#define R_EN 4 // define pin 2 for R_EN pin (input)
#define R_IS 5 // define pin 5 for R_IS pin (output)

#define LPWM 6 // define pin 6 for LPWM pin (output)
#define L_EN 7 // define pin 7 for L_EN pin (input)
#define L_IS 8 // define pin 8 for L_IS pin (output)
#define CW 1 //do not change
#define CCW 0 //do not change
#define debug 1 //change to 0 to hide serial monitor debugging infornmation or set to 1 to view

#include <RobojaxBTS7960.h>
RobojaxBTS7960 motor(R_EN,RPWM,R_IS, L_EN,LPWM,L_IS,debug);

void setup() {
  //Initiate Serial communication.
  Serial.begin(9600);
  motor.begin();
  pinMode(SensorPin, INPUT);
}

void loop() {
  // read the value from the sensors:
  SensorVal = analogRead(SensorPin);
  change = PreviousSensorVal - SensorVal;
  PreviousSensorVal = SensorVal;
  Serial.print(SensorVal);
  Serial.print("\t");
  Serial.print(change);
  Serial.print("\t");
  if (SensorVal > (Middle + Cushion)) {
  motor.rotate(80,CW);// run motor with 100% speed in CW direction
  Serial.println("motor is turning CW");
  delay(50);//run for 50 ms seconds
  motor.stop();// stop the motor
}
  if (SensorVal < (Middle - Cushion)) {
  motor.rotate(80,CCW);// run motor at 100% speed in CCW direction
  Serial.println("motor is turning CCW");
  delay(50);// run for 50 ms seconds
  motor.stop();// stop the motor
}
  Serial.print("\n");
  delay(100);
}


texts: Do cold battery capacity de-ratings apply at low currents?

texts:
I've read that NiMH and Lithium chemistries will only supply around half of their rated capacity when used at low temperatures (say around 0 degrees C).

Many sources also mention an increase in internal resistance and it is inferred that the two characteristics are related.

Now what if I'm working on a very low current application relative to the C rating of the battery? Say 0.01C. Do I still have to assume I will only get roughly half the mAh out of the battery? (My reasoning is that at low C discharge rates the internal resistance of the battery is less significant.)


texts: ATX PSU +12V outputs connected in parallel

texts: I need +12V and around 10A for my project. Each wire on the ATX supply I bought is stranded 20 AWG and is rated for less than 10A. What would happen if I connected multiple +12V wires in parallel to divide the current among the thin wires? The PSU says that it can supply 16A out of the +12V output.


texts: I have extract this schematic from youtube (only charger parts) and create this on falstad because I want to create 3.7V battery charger. The original charger use 1N4007 diode with BC547 transistor. I have only 1N4001 diode and 2N3904 transistor, can I use this in place? Is this circuit good or bad? I read my specs for my battery and I read 4.2 V for charge and 2.75 V for discharge, 3.7 V 70 mAh, but, my first TP point is 5 V. But probably, the battery act as resistor and then voltage down. I learn about to simulate lipo for confirm that. For any advice, thank you, sorry for my english.


texts: Increasing Terminal Block Rating by Combining Contacts

texts:
I understand that by using multiple wires, we could increase the surface area of the conductor and thus, allowing more current to pass from one point to another. Does that apply to contacts on terminal blocks as well? Here is an example:

Say if I had a terminal block where each contact is rated at 15A, and wish to pass 20A current through it. So if I were to use cable(s) rated at 20A, to connect/jump 2 or more separate contacts on the terminal block, will those contacts then able to support 20A of current due the increased surface area?


texts: Is my understanding of current, voltage, and resistance correct?

texts:
Im currently a senior in highschool. So I know that voltage is the potential difference per unit charge, or from my understanding the work done to move a unit charge from point a to point b without any acceleration. Current is simply the # of Coulombs that pass through a point in the circuit over time. Resistance restricts the coulombs that is able to pass through it. Why is it that higher voltage leads to higher current when the load resistance is constant? Teachers often talk about voltage as potential energy, but isnt the voltage just the work done to move a unit charge between two points. The only way that this makes sense to me is if I think about resistance as the electrons completely stopping or stop at some arbitrary point, and so voltage accelerates these electrons to speed v. And speed v gives you the current.

How does this all tie in with voltage drop? So is it that we say that work is used up? So if we have a current I where the electrons are moving at speed v, do we say that larger resistances "use up" the voltage, while smaller resistances "use less" because the smaller resistances decelerate the electrons less than the larger resistances?

No (water) analogies in your response please. Sorry for the noooby question.


texts: What can cause CPU Vcore to jump up by 20% permanently without corresponding change in CPU load?

texts:
One of my servers shows strange change in its monitored parameters. Last Sunday evening one of voltage measures ( in0 which I think is Vcore) suddenly increased by 20% from ~1V to ~1.20V on average. There is corresponding significant increase in reported CPU core temperatures and CPU fan speed but very slight increase in CPU frequency (1.20GHz -> 1.25GHz) and CPU base load.

What could this mean? I suspect failing PSU or MB. Is there any other good explanations for such behavior? There were no changes of server hardware, BIOS setting or software at this point of time.

Server MB is Gigabyte GA-MA69VM-S2 with AMD Athlon(tm) Dual Core Processor 4450e. OS is Ubuntu 12.04.2 LTS with kernel 3.2.0-45-generic. Monitoring is done by lm-sensors 1:3.3.1-2ubuntu1. Current output from sensors command is below graphs.

k8temp-pci-00c3
Adapter: PCI adapter
Core0 Temp:   +38.0°C
Core0 Temp:   +35.0°C
Core1 Temp:   +35.0°C
Core1 Temp:   +37.0°C

it8716-isa-0228
Adapter: ISA adapter
in0:          +1.20 V  (min =  +0.00 V, max =  +4.08 V)
in1:          +1.89 V  (min =  +0.00 V, max =  +4.08 V)
in2:          +3.36 V  (min =  +0.00 V, max =  +4.08 V)
+5V:          +2.98 V  (min =  +0.00 V, max =  +4.08 V)
in4:          +3.07 V  (min =  +0.00 V, max =  +4.08 V)
in5:          +3.23 V  (min =  +0.00 V, max =  +4.08 V)
in6:          +0.10 V  (min =  +0.00 V, max =  +4.08 V)
5VSB:         +3.02 V  (min =  +0.00 V, max =  +4.08 V)
Vbat:         +3.02 V
fan1:        1555 RPM  (min =    0 RPM)
fan2:        2860 RPM  (min =    0 RPM)
temp1:        +29.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermistor
temp2:        +34.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermistor
temp3:        +31.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermal diode
cpu0_vid:    +1.200 V
intrusion0:  ALARM


texts: ac current measured in a 3 phase dc rectifier

texts:
Hi have a 3 phase DC rectifier: input 400V AC; output up to 10V/2000A DC

I'm aware that it's normal to have some AC current in the output of the rectifier and in this particular case it is acceptable up to 5% Ripple.

However something odd is happening. Once the rectifier is ON without any load, i'm getting close to 0V AC in the + output terminal (which is good), but i'm getting 6 to 9V AC in the - output terminal.

What could be the problem? What should i be looking at?

Thank you!


texts: Is it possible to mirror the Net label in Altium 20.1.12?

texts:
The x and y hotkeys work for other components, but not the net label, which according to the 17.1 and 20.2 official website guide should work. I've also gone into the properties tab of the net label, but the only thing I can do is rotate, which will make the letters upside down.
Here are the links for the websites I looked at: 17.1 and 20.2
Update: the properties in the netlabel allow for mirroring, I just didn't see an actual mirror button that is present in other components. You have to manually mirror it, but hotkeys still don't work which honestly isn't a problem.


texts:
I have the following circuit:

simulate this circuit – Schematic created using CircuitLab

I need to determine period of oscillations for the given circuit and to sketch waveforms of the voltages at nodes n1, n2 and n3.

Values of the resistances and capacitance are known and OPamps are considered to be ideal.

$$R_1=47k\Omega\\ R_2=39k\Omega \\ R_3=10k\Omega \\ C=100nF$$

Basically, what I can see here, is that this circuit consists of an inverting amplifier in series with an integrator (correct me if I am wrong), but I really cannot see the way to sketch the waveforms required since I cannot see what is actually going on here.


texts:
Firstly, I am a ME seeking advice from EE's. I have a Quadvolt voltage data acquisition box from Omega (P/N:  OM-CP-QUADVOLT-30V) http://www.omega.com/pptst/OM-CP-QUADVOLT.html, that I intend on using to monitor current through a 100A 50mV current shunt in a 12 volt solar system that powers a light.

I want to monitor current in the positive conductor between the battery and the solar/light controller. My problem is that the Omega box cannot handle reverse polarity. I am concerned that when the system switches from charging to drawing power from the battery, the current direction will switch and therefore (I would assume) the polarity at the current shunt would switch, correct?

If my logic is correct I want to be able to protect the Omega box. I had landed on using an N-Channel MOSFET in series with the negative side conductor from the current shunt to the Omega box. Then I got lost in all the terminology. Since the voltages I am monitoring are so low, on the order of 50mV, will a MOSFET protect the box without causing noticeable voltage drop? Will negative 9-13 volts be enough to actuate the switching device and protect the Omega box in a reverse polarity situation?

Found this recommended on another page https://www.digikey.com/product-detail/en/SI4838DY-T1-E3TR-ND/SI4838DY-T1-E3TR-ND/1656477. Would this work for my application? Thanks so much for the help! I'm lost when it comes to this stuff!


texts: Is the effect of capacitors and inductors directly proportional to frequency?

texts:
I'm reading Practical Electronics for Inventors and a curious sentence has come up.

  The effects of
  capacitance and inductance are generally more significant at high frequencies

This makes sense to me for inductance, since it's directly proportional to frequency in the formula, but I was wondering why capacitance and its effect are also greater with increased frequency when in the formula \$\frac{1}{\omega \cdot C}\$
it's clear that the frequency is inversely proportional to the capacitor's impedance. Doesn't this mean that with greater frequencies the effect of the capacitor is lowering, which also means that for lower frequencies the capacitor's [edit:] effect increases?


texts:
anyone has seen the component in picture?
I have searched google but no results.


texts: Standard component size for antenna matching circuit

texts:
I am fairly new to the RF world. It was certainly not my strongest subject. I am currently designing a board that uses the SIM868 module (GSM) and I need to design an antenna matching circuit. In the case above what size component should L1 be? 201, 402?

simulate this circuit – Schematic created using CircuitLab


texts: Functional principle of comparator based rectifier

texts:
I stumbled across the circuit shown in Fig. 36 on PDF page 21 of Jim William´s "High Speed comparator technieques" Application note (see Link)and also the attached schematic which shows a fast precision recitifier.

Can someone explain how this circuit works? I don´t get it based on the description in the appnote, especially the "biasing" of the diode bridge.

P.S.: I also have done an LTSpice simulation (luckily, besides of the special schottky diodes, LTSpice has all the models of the used parts ;-) ).

When looking at the "output" of the bridge the simulation only shows "spikes" (positive and negative) at the moments where the comparator outputs switch, but no rectified input signal

[EDIT]: Added schematic to this question
[EDIT2]: Added hyperlink to LTSpice simulation file LTSpiceSimulation


texts:
What is Virtual Encoder and how does it work? I found this phrase in swing gate operator
(FAAC s418)datasheet. It says above "New control board with anti-crushing system and virtual encoder for inversion on obstacles".
( but not in datasheet)


texts: Beat detection circuit with elect mic and arduino

texts:
I need some kind of sound sensing in my microcontroller project. I have a condenser microphone and some transistors around, so while prototyping I found this circuit:

With my parts on hand and removing the C2 cap because it didn't work, I got this working circuit:

However, the signal amplitude is very low, I get peaks only when clapping. The noise floor is around 225mV and my peaks are at 230mV at best.
So which parts in my circuit do I have to change to get stronger peaks?
Do I add another transistor or change some resistors?
Also is there a better solution for this usecase like a dedicated chip? Ideally I want something like the sparkfun sound detection modules but integrated on my own PCB.


texts: I have an AC signal (500 - 1000Hz) 1v peak to peak that sweeps around 0v. The signal needs to be shifted to 0.5 -2V, a gain of 1.5... The power supply is +-10V. Just looking for someone to point me in the right direction, and if anyone has examples of similar circuits that would be great.


texts:
I have this:
LIBRARY ieee ;
USE ieee.std_logic_1164.all;
use ieee.numeric_std.all;
USE ieee.std_logic_arith.all;

ENTITY FullSubtracter1 is port(In1, In2: in std_logic_vector(31 downto 0);
                           Overflow: in std_logic_vector(0 downto 0);
                           Diff: out std_logic_vector(31 downto 0));
end FullSubtracter1;

ARCHITECTURE FullSubtracter1_1 of FullSubtracter1 is
signal tmpDiff: std_logic_vector(32 downto 0);
signal tmpOverflow: std_logic_vector(0 downto 0);

BEGIN
   tmpDiff <= std_logic_vector(conv_signed(to_integer(signed(In1))
                        - to_integer(signed(In2)), Diff'length), Diff'length);

   Diff <= tmpDiff;
   tmpOverflow <= '1' WHEN (In1(15)=In2(15) AND tmpDiff(15)/=In1(15)) or
                        (In1(15)/=In2(15) AND tmpDiff(15)/=In1(15)) ELSE '0';
   Overflow <= tmpOverflow;
END FullSubtracter1_1;

And I get on this line of code:
tmpDiff <= std_logic_vector(conv_signed(to_integer(signed(In1))
                        - to_integer(signed(In2)), Diff'length), Diff'length);

The below messages:

Error: C:/Modeltech_pe_edu_10.4a/examples/Full_Subtracter1.vhd(16):(vcom-1078) Identifier "signed" is not directly visible and then this message:

Error: C:/Modeltech_pe_edu_10.4a/examples/Full_Subtracter1.vhd(16): (vcom-1394) Type conversion operand must be a single expression that is not a range.

Any suggestion?


texts: How does autoranging work in a multimeter? What is the circuit?

texts: I was curious how this is done. It seems you would have to vary the voltage and current to measure resistance from 1ohm to 10Mohm.


texts: Why does my rectangle function on a FPGA look like this?

texts:
I programmed my FPGA to create a simple 1 MHz rectangle function. But when I display the resulting function on my oscilloscope it shows some oscillation after the edges.

At first I thought this might be the the Fourier components, but this doesn't seem to fit(eg. it's not symmetric).

What creates these oscillations? I have a few guesses, but no idea which, if any, is right:

some unintentional LC-circut
a badly configured PID inside the FPGA
crosstalk


texts: Why does LTSpice say that my "Matrix is singular" for this ideal-transformer circuit?

texts:
I'm trying to do find the voltage over R1 in the following circuit, where L1/L2 is an ideal transformer. LTSpice complains that the "Matrix is singular". Why? I've tried to play around with lots of different values in order to see if it's a problem with approximation.

The numbers after "AC" are the max amplitude and phase (in degrees).


texts: A question about ringing phenomena and resonance

texts:
Below is an LC circuit fed by a 1V 10kHz square-wave. As you see the output is a sinusoid, which would be max. if it were produced by an input at resonance frequency.

And here below the same circuit's output for a 10Hz square-wave input. As you see the output is a ringing signal which looks like a damped oscillation at resonance frequency.

Why is ringing occurring here for square-wave inputs at only low frequencies? And is there a relation between Gibbs phenomena and ringing? And why ringing occurs near the rising and falling edges?


texts:
I am going to use TZC3 family trimmer capacitors from Murata (datasheet, skip to TZC3 section).

It has one of its terminals very close to the mounting surface, and theoretically if rotor is pressed too much (or device is overheated during soldering causing damage to the body), body can be bent and it potentially causes shortage of the rotor with the tracks on the surface of PCB underneath. No clearance size value is given in datsheets (I have no real device on hand to measure).

There're a number of slightly varying datasheets available on the internet, none of them mention that area underneath must be restricted.

Do I bother about it too much, or risk is real?

While writing this question I have got an idea to simply extend the track connecting to the rotor terminal to the central point of the device PCB area so that if issue happens, it shorts to the same signal. But one of the capacitors in my design is having power rail under it, and it seems I will have to divert it out of the area.

Update:

Following Finbarr's comment I did the following layout:

removing ground potential in proximity with the bottom knob.


texts: Interfacing an optoisolator with arduino

texts:
I recently bought this optoisolator (datasheet PDF).  I am wondering how I can connect it to my Arduino. I have some ideas, but I am afraid to test them because I might damage the board.

What I am trying to do is to connect and disconnect a circuit. What should I connect to the pins on the breakout board? The pins are labeled:

OUT1
HV
OUT2
HVG
NC
IN1
IN2
GND

and the schematic is here.


texts: How can I use relays and deal with reverse polarity with the Arduino?

texts:
I have a toy car that I wanted to make autonomous.

It has a motor for rear drive (seen in the bottom of the photo hidden in the gear-box) and a motor for rack and pinion steering (located just above the webcam in the photo). Reversing the polarity allows the car to reverse, as well as steer in the opposite direction.

I have successfully added break out cables from these two motors, hooked up in addition to the toy's original wires to them. These cables (red/black for drive motor and light/dark green for steering motor in photo) have been hooked up to an Arduino. I was able to control both motors with relative ease using Node.js.

However, the toy car has four 1.5v batteries to power it. When I check how much power arrives at the motors using the Arduino, it's under 1v, and the toy car can't drive when placed on the ground, nor can it steer the wheels (I just hear a click and see the rack move about 1mm each way).

If I check with a multimeter, the lines seem to get ~5v, but once they're connected to the motors, they drop to under 1v.

I tried desoldering the original lines that went from the car's PCB to the motors, but it didn't seem make a difference. If I use the car's original remote control, the wheels fly along and receive the normal ~5v.

I am wondering if it's possible to use relays to let the Arduino control the switching and polarity, but have the car's original power source provide the final power. I'm aware how relays work, but I'm curious if they're compatible with requiring the polarity switch. If it's possible, would I need special relays or just one of the normal Arduino ones?

In case you couldn't tell, I'm new to Arduino, with this as my first project.


texts:
I have only a basic understanding of power factor correction, but I am curious why it is necessary for manufacturer's and their customers to be concerned with ensuring a high power factor, other than to avoid larger bills* from the electricity supplier.

Why does the supplier not - that is why can they not, I assume - perform this correction with some large capacitance on their end?

*To clarify, I mean manufacturers of large equipment, and their industrial customers buying that equipment.


texts: How to make a differential measurement using two single-ended circuits that are high-z isolated?

texts:
Consider this system: There is an AC source that is differential w.r.t to ground. To measure this signal, I setup a diff-buffer and then feed the output to an ADC which measures the differential signal w.r.t. the same ground.

I need to make the same differential measurement now. However, I have two circuits that can only access one terminal and therefore, make only single ended measurements and their systems are referred to the same ground via a high impedance connection. Is it possible to design a front end to do so?


texts: Does Shielding "Electrically" shield "Magnetically" too?

texts:
I know it sounds like a newbie question but I can't wrap my mind around it. An electromagnetic field is electric + magnetic field.

So this means that when shielding an equipment offensively, for example from avoiding causing interference with other electronics, we need to shield the electromagnetic waves, that means both electric and magnetic shielding.

So if we put say a radio inside an aluminium box, aluminium is pretty much the most cost effective material you can find. Some may use copper but aluminum is more cost effective.

Now an aluminum box will shield the electrical field very efficiently given if the box has no holes or seams, or if the cables coming out of holes are properly shielded and grounded.

But what about the magnetic field?

Aluminum has very low permeability. So how can the aluminum box shield nearby equipment from the magnetic field of the radio inside it? It does shield the electrical field, but not the magnetic?

Can somebody explain to me how shielding works with electrical/magnetic waves? Because I can't wrap my head around it how can it shield the electrical part but not the magnetic?

Does magnetic field leakage pose any noise danger to the nearby equipment from this theory perspective?


texts:
I'm familiar of course with the preferable way to mix audio, that is prior to amplification. However, I have a few mobile radios with roughly 1 watt audio outputs, which I would like to send their audio to a single monitor speaker - and simplify things.

I suppose there are 2 ways:

Use larger variable pots for each of the inputs. Simple but the pots might be more expensive.
Attenuate the audio from the radios - could use a fixed resistor for this on each. Then amplify the combined audio.

I was thinking #1 - passive - would be easier and cheaper, but  #2 may make more sense. Am I missing something?


texts: What capacitors do when it is connected in Series and parallel to a AC input

texts: I have seen in many circuits the capacitors are connected in series and parallel with the AC line. What the capacitor actually does when it is in series and parallel. I know capacitors passes AC through it... explain me. I'm beginner in electronics..


texts: Why don't we get electrocuted when touching a pot sitting on an induction cooker

texts:
As the title says, why does that not happen. As far as my understanding goes, an induction cooker is a coil of conductive wire through which AC is pumped. This generates an oscillating magnetic field around the coil, which in turn generates a DC current in the pot sitting on the cooker. Since the pot is not made of a superconductor, the current flowing through it heats it up, and that's where we get the electricity from.

Now this is where i get confused. First, yes, there's a current, but is there a potential difference between any points, or are the electrons just really excited ? If there's a potential difference between any 2 points in the pot, then why does touching it not give us an electrical shock?


texts: Dynamic power dissipation of a Cmos inverter with relation to it's geometry

texts: I know that the dynamic power dissipation of a CMOS inverter is defined by the equation: Pd = (Cl)(Vdd^2)(fb). My teacher challenged us to find ways to reduce power dissipation besides the obvious ones (reduce bitrate, Vdd, etc.), and apparently the power dissipation is inversely proportional to the CMOS geometry. I'm assuming this is because changing the geometry will change the current through the MOSFET, but the current is proportional to W/L (where W is the gate width and L is the channel length). So if the power dissipation is inversely proportional, does that mean in relation to W or L?


texts: I need help understanding a circuit simplification in my textbook

texts: The question I have about this problem is how to obtain the 80 kOhm equivalent resistance for the circuit attached to the conductor. What I did was I combined the 240 kohm and 60 kOhm resistors in parallel and then combined their equivalent resistance with the 32 kOhm in series but the value I obtained did not match what is described in the textbook. I also know that I cannot combine the 32 kOhm resistor with the 240 kOhm resistor in series so I am stuck on how to obtain the 80 kOhms that the book has.


texts: How to calculate size of filter capacitor for microcontroller that has changing loads on its 5V supply

texts:
How do I calculate the size of a filter capacitor to reduce the ripple when I have a microcontroller on the same regulated power supply as a high current load like an LCD strip or a motor controller? (I'm aware of the need to use flyback diodes on inductive loads.)

If I'm building a power supply that rectifies AC and filters it, there are lots of articles out there that describe how to calculate the size of the filter capacitor, e.g.: https://makingcircuits.com/blog/calculate-filter-capacitor-smoothing-ripple/

The formula for that is C = I / 2 x f x Vpp, where I is the load current,  f is the AC frequency (usually 50 Hz or 60 Hz, and Vpp is the allowable ripple.

All the searches I've done lead me to articles about filtering ripple on AC power supplies.

However, I'm not trying to smooth ripple from a rectified AC supply. I'm trying to smooth out variations in an already regulated 5V supply as the load to the supply changes.

Say, for example, I have a regulated 2A 5V supply that's driving a 1.5A LED array AND an Arduino-based system that draws ≈200mA. I am feeding the 5V from the supply into the Arduino, and also using it to drive the LED array. I'm under the 2A limit of the regulated supply, with a little "wiggle room", but concerned that as the LED array turns on and off, it will cause droops and spikes in the regulated 5V supply as the power supply lags slightly in adjusting the output voltage for changes in load.

Assume the Arduino can tolerate ±0.5V on it's 5V supply. I imagine the LED array's load spikes are going to be nearly instantaneous, like switching on and off a resistive load. (Assume the 5V supply is a typical switching supply. I don't know how to estimate its max voltage variation under changing load, or recovery time, and need help with that bit.)

How do I calculate the rating of a filter capacitor to put on the 5V rail that feeds the Arduino to smooth its input voltage as the load to the power supply changes?


texts:
I'm debugging an STM32 with gdb. For some reason my program crashes, and gdb gives the following.

  Note: automatically using hardware breakpoints for read-only
  addresses.

  stm32f2xxx.cpu -- clearing lockup after double fault

  Program received signal SIGINT, Interrupt. 0xf8ad0300 in ?? ()

I do not understand what this is saying. What is a lockup? What is a double fault? What is a .cpu file?


texts: Gigabit Ethernet switch unused RGMII/MII/RMII interface

texts: I am working on 5-port gigabit Ethernet switch based on Microchip KSZ9897. As the KSZ9897 is 7-port gigabit Ethernet switch (5 x 1000BASE-T/100BASE-TX/10BASE-Te IEEE 802.3 + 2 x  RGMII/MII/RMI) and I am using only the 5 ports, I just wonder what to do with the remaining  RGMII/MII/RMII unused interfaces (pins). Shall I put it unconnected? I didn't find anything from the documentation about the particular situation. I suppose the question does not depend much on chip manufacturer, but is related to unused  RGMII/MII/RMII interface in general.


texts: How to measure a dc or ac signal using PC as oscilloscope?

texts:
I want to measure for ex a battery 0.7V dc using a program like Visual Analyser/Soundtrack Oscilloscope/jDTF/Scope/xoscope. I connect the negative pole of the battery to sleeve and the pozitive to ring

But I dont see any changes on soundtrack oscilloscope. I tested it with microphone on the same plug in and it was respondign to my voice, but when I plug in the dc voltage nothing is changed, there is only noise. Do you know what am I doing wrong?


texts: What does "600 : 600 Ω" mean for an audio transformer?

texts:
I found audio transformers online having the following specification:
600 : 600 ohms.

My question is what does it mean?
Does it mean that it is simply an isolation transformer?
Or is it in some way used for impedance matching?

How can it be used for impedance matching if both the primary and secondary have the same resistance? Lets say for example I have constructed an amplifier with output impedance of 600 ohms. The speaker has an impedance of 4 ohms. How can this transformer be used to match the impedance?


texts: For an Arduino and ESP8266, can I power up the ESP8266 from a set of 2n2222 transistors?

texts:
I am trying to power-on my ESP82666 and it draws about 300ma on a 3.3v.

Can I power it up just like this, but instead put some sort of 2n2222 in place of the other transistors?

BTW: I am new to electronics, and I am learning a great deal, so please be patent with me.

Here is a simular post: How can I turn off a 3.3V circuit with a 3.3V microcontroller, and someone is trying to sort of do the same, but with different logic.

-- or --


texts: Questions on rechargeable battery pack configuration and calculations

texts:
I'm looking at making a battery pack for a medical device (CPAP) that would allow its use while camping.  I'll tell you what I need and then what I'm planning.

What I need:

24v at 3.75 amps DC output, typically at 58W, max at 104W, according to the manufacturer docs
approximately 50 Ah per day, which includes a 50% safety margin (ResMed Battery Guide)
at least 2, preferably 4-5 days capacity
reasonable portability.  of course smaller/lighter is better, but I'm not looking to take it back packing, but if I can't lift it or it won't fit in my van...

What I'm assuming:

4-5 days would mean 200-250 Ah total capacity
total capacity is the sum of all cell's capacity and configuration doesn't affect this.
amp draw is divided across all cells, and configuration doesn't affect this either.
Ni-MH batteries have a flat enough discharge that they will work within limits from full to nearly fully discharged, allowing me to get most of the power out of them. (I've also considered deep-cell batteries.  If this is a better idea, please explain why.)

What I'm planning:

100 Ladda Ni-MH batteries from Ikea which look to be fairly true to their nominal 2450mAh rating (according to Test/Review of Ikea Ladda AA 2450mAh (White) 703.038.76) for a total nominal capacity of 245Ah, or almost 5 days with more than 2 days safety margin.  Also, quite cheap for the capacity.
5 banks of 20 batteries in series for a voltage of 1.2*20 or 24V
the 5 banks connected in parallel so all capacity is accessible

So based on this I have several questions I'm hoping you guys can help me with.

What do I have wrong?
Can the batteries be recharged in this configuration?
What would I need to make/buy/do to recharge them?  Is it as simple as reversing the leads and connecting it to a 24V DC source?  Probably not.
I would like to have a "smart" charger that I can plug in, leave, and have it done when I get back 8-10 hours later without worrying about overcharging.  What would be required for that?
Can it be charged at any point? For example, only used 1 night, but I happen to have access to a wall outlet the next day, so I top it up?

My experience with this sort of thing is limited, but I'm a Mechanical engineer and had limited electronics classes back when I was studying, so I can usually understand what is explained to me.


texts: Where does the power supply go in an SR Latch?

texts:
I understand how an SR Latch works: is S is 1, it will set Q to 1. If R is 1 it will set Q to 0.

If both S and R are 0, the value of Q should remain unchanged (right?). So the circuit has these stable states:

Now my question is: If 0 voltage is flowing through both the input wires, how can the 1 still exist in the circuit? There must be an external power supply? (I'm assuming there must be because, if you disconnect your computer, everything in the RAM gets wiped) but where would this power supply go without disrupting this circuit?

I hope my question was clear. I just don't understand how it can keep its value when the inputs are 0.