texts: Ebike battery not charging after cell change from Ni-Cd to high capacity Ni-MH

texts:
I recently replaced the cells in my ebike which consisted of 20 Ni-CD Size D (1.2V) 4,000mAh with 20 Ni-Mh Size D (1.2V) 10,000mAh batteries.

Before installation, I charged up each battery to ensure it was working, and connected the cells exactly how the old cells were connected. I tested the battery on the bike and it ran beautifully.

However, when it came to charging the battery, it simply would not charge. I can confirm the charger was working with the previous cells, but since I’ve changed them, the charger only shows a green led. The charger that I am using is rated for Ni-Mh batteries and is 24v 1.8A.

Are some built in protections preventing it from charging and is there anything I could do to get it charging again? I was looking at various chargers online with a similar rating but am unsure if i purchase one, if the same issue would arise.


texts: What is better to use, FeRAM or MRAM? Why?

texts:
FeRAM and MRAM have almost the same characteristics from electronic point of view although the physics behind is different - feroelectric material and magnetoresistive material. Their properties: non-volatile, write/read cycles number, write/read speeds etc are almost the same. Then why a company is choosing to use FeRAM instead of MRAM, or MRAM instead of FeRAM?

Do you think that this are the future memories?


texts:
In a monostable configuration of the 555:

http://circuitdigest.com/electronic-circuits/555-timer-monostable-circuit-diagram

I have connected pin2 to the ground all the time. My goal is that once the circuit is powered on it starts the counting down right away then turns off after x seconds but this is not what's happening.

The output load will be turned on this way all the time.

How to do it properly then?

Thanks


texts:
How can I calculate the current carrying capacity of a DC copper bus bar with respect to temperature?

Bus bar specifications:
Width=40mm
Thickness=6mm


texts:
I'm considering using a tps61165 led driver for an LCD backlight. While I know it is far from recommended, I quickly breadboarded the typical application circuit using TH components that match the recommended SMD parts as much as possible, and used a SOT to DIP adapter for the IC.

In my case I have to go from 5V to 12.8V @ 40mA. (2x4 LEDs). For some reason the circuit works fine when I take out the C4 4.7uF input cap. When I do use it, I only get a really low output current, barely enough to light up the LEDs.

Why could this be the case?

-- edit --

Notes:

C4 is on the far right in this picture
where I put it.
R4 and R5 are not in this picture.
R1 is 2x10R
L1 is a Bourns RLB0712-100K
D1 is an 1N5817

While I was editting the post to add the breakout picture, I noticed something new: When I enable power without C4 present, it will start up and light the LEDs at the desired power. Then I can add C4 while it is running and it will keep running and light the LEDs even brighter. But when I power up the circuit with C4 already there, it will get stuck in a low power output.

The location of adding C4 (after the circuit is running) also seems to matter. When I put it far away from the IC, it will increase brightness, but when I add it close to the IC when the system runs, it will shut down the cicruit.

Also when I power up the circuit with C4 present, I will get a weak constant output current when C4 is far away from the IC, but I'll only get a short blink once when I put it as close to the IC as the breadboard permits.


texts: How to write VHDL program to send command to PS2 device

texts:
I'm using Quartus II 13.0sp1, DE1 Board for testing, and Cyclone II FPGA EP2C20F484C7N.
I need to write program in VHDL that sends command to device. I have already created entity and architecture which I successfully used to receive keys from keyboard. Now I need entity that send command to mouse, since mouse expects me to send it commands to start streaming mode.

My biggest problem is that I don't know how to DECLARE and USE ps2_clk and ps2_dat pins to send command to mouse and to receive data from mouse (using same pins to both-way communication).
Just after I send 11 bits to mouse, I need to receive one bit using same pin (ps2_dat), and after that receiver ACK byte from mouse using that same pin. Also before I send command I need to pulldown clock line low, for period of 100 microseconds, and after that I need to release clock line so that mouse can generate clock.

I hava no idea how to implements this. Or maybe I misunderstood protocol?


texts: Unable to set Pin Change Interrupt on ATmega328p

texts:
so I am working on learning some AVR programming with the ATmega328p.  I am trying to set up a pin change interrupt and this is the code I am running.  However, the interrupt never seems to trigger.  Is there anything I am doing wrong?

Is there some way I can test this outside of using a board, like in simulation?  I am using Atmel Studio.

Thanks!

#include <avr/io.h>

#define F_CPU 16000000UL
#include <util/delay.h>
#include <avr/interrupt.h>

#define ON_B0 PORTB |= (1 << PORTB0)
#define OFF_B0 PORTB &= ~(1 << PORTB0)
#define TOGGLE_B0 PINB |= (1 << PINB0)

ISR(PCINT1_vect)
{
    // Check if pin B1 is low)
    if ( !( PINB & (1 << PINB1) ) )
    {
        ON_B0;
    }
    else
    {
        OFF_B0;
    }
}

int main(void)
{
    DDRB |= ( 1 << DDB0 );
    DDRB &= ~( 1 << DDB1 );

    PCMSK0 |= ( 1 << PCINT1);
    PCICR |= ( 1 << PCIE0);

    sei();

    while (1)
    {
        PORTB |= ( 1 << PORTB1);
    }
}


texts:
I have an 18 V dc linear power supply rated for 7.5 A.

I am applying an electronic load at 2 A constant current prior to applying ac input to the power supply. After applying the ac input, the power supply fails to output a volt. If I repeat this process at 1 A on the electronic load the power supply will power up and output 18 V.

I tried this same set up with a similar switching PS and the PS came up regardless of the load applied.

The linear supply i am working with tests good if i apply no load or up to 1.5 A at initial power up. And after it is powered up i can increase the load to full load (7.5 A) and the power supply maintains 18 V dc.

Question 1 - Does a linear supply have a load rating at initial power on?

Question 2 - Does a switching power supply have a load rating at initial power on?

Also, When the linear power supply is driven to over current (about 9 A) the voltage drops out and the electronic load displays about 1.75 A. Once I reduce the electronic load to 1.75 A the output comes back on.

Question 3 - is this value of 1.75 A significant to the load value that the power supply can operate at initial power on?

Question 4 - Is the difference between the over current trip point and the point where the power supply recovers called hysteresis?


texts: Can I use a DC-DC buck converter with an arduino

texts:
I'm just starting out with electronics and arduinos, but I want to ask if i'll be safe using an LM2596S DC-DC step down buck converter as the regulator for my arduino project?

I have a few to hand and i'll be using 12v supply for the project using the converter to step it down to 3.3v, or is this not a good idea?


texts:
In Altium Designer, I'm using Keep-out layer lines to enforce the manufacturer's board-edge clearance restrictions. The problem is, that the top layer polygon will pour around these lines, which is not necessary.

How can I make the polygon pour act like the keep-out layer was a silk-screen layer, i.e. just ignore it.

If I set the clearance rule to 0 or matching "NOT OnLayer('Keep-Out Layer')  ", it will have no clearance but still have no copper directly below the line.


texts:
So basically the buttons work and such but in my second always loop, it skips the if statement that turn on led_light when >=2 but it turns on the led i have programed for >=5 when I press the button 5 times. If anyone can help fixing my if statement that would be awesome.

`timescale 1ns / 1ps

module card_algo(clk, posb, negb, led_light, led_big,reset);
input clk;
input posb;           //count up button
input negb;           //count down button
output reg led_light; //led represents light bet
output reg led_big;   //led represents big bet
integer count = 0 ;    //count
input reset;

wire btn0_state, btn0_dn, btn0_up;
    debounce upcount (
        .clk(clk),
        .btn_input(posb),
        .output_state(btn0_state),
        .output_ondn(btn0_dn),
        .output_onup(btn0_up)
    );
    wire btn1_state, btn1_dn, btn1_up;
    debounce downcount (
        .clk(clk),
        .btn_input(negb),
        .output_state(btn1_state),
        .output_ondn(btn1_dn),
        .output_onup(btn1_up)
    );

 always @ (posedge clk)
 begin : ButtonPress
    if (btn0_up == 1)
    begin
       count <= count + 1;
    end      //if up button is pressed, count is raised
    else if (btn1_up==1)
       count <= count - 1;;
 end

always @ (posedge clk)
begin: Lights
  if (  count >= 2)
  begin
    led_light =1;
  end
  if (count >=5)
    led_big=1;
  else
    led_big=0; led_light=0;

end

endmodule


texts: What is the 0V reference for MOV's input protection on power supply?

texts:
In some application notes for MOVs I see example usage in power supply design where each input line (N, L) from the mains are protected with a MOV to a ground voltage reference (as well as a differential mode MOV protection between the input lines)
What I don't understand is what is the 0V "ground" reference these application notes are referring to?
It is both regulatory and practically impossible to use the PE (=FG) since even the smallest MOV current could trigger the earth protection circuit breaker.


texts: Power-down sequencing with a "hard" power switch (stepper driver)

texts:
I'm designing a stepper motor controller and would like to have some advice on sequencing the shutdown process with a "hard" power switch. The Toshiba TB6560 driver that I'm using requires a specific power-up and power-down sequence to avoid damaging the chip (\$V_{DD}\$ \$\rightarrow\$ \$V_{MA}\$/\$V_{MB}\$ \$\rightarrow\$ \$\textit{Control Inputs}\$ on startup and the reverse on shutdown, similar to a FILO buffer). I'm trying to find a good solution for powering the sequencing circuitry, as well as the logic chips it supports, after the main power is removed.

The sequencer is built with discrete components and uses RC timing with op-amps to delay the output lines at specific intervals as shown in the plot below. When the Enable line goes high, the outputs are turned on sequentially; the on/off behavior is staggered such that the first line to go high is the last one to go low. The three outputs from the sequencer are used to drive two MOSFET switches for \$V_{DD}\$ and \$V_{MA}\$/\$V_{MB}\$, as well as a 4066 quad switch for the various \$\textit{Control Inputs}\$.

The schematic for the power supply portion of my stepper motor controller is shown below (click for full-size view). I've marked up the schematic to correspond to the following numbered list:

C1 provides energy storage to operate all of the logic circuitry when the power is cut. I calculated the current draw to be 26 mA across the entire controller, excluding the stepper motor itself, so this supplies enough power for about 350 ms of operation after the main switch SW1 is turned off. Based on this timing, the capacitor will discharge to 15 V, which is the minimum input voltage required for the LM7812 regulator U1.
R1 is a 10 ohm power resistor for C1 to limit the inrush current to about 2.4 A, which is within the limits of the power supply PS1. From zero volts, C1 will charge in about 100 ms.
R2 is a 100 kOhm bleeder resistor to ensure C1 is discharged when the unit is turned off.
D1 is a low-forward-voltage Shottky diode to protect the output of PS1 when C1 takes over during shutdown. The forward voltage drop should be 0.5 V or less in this application, so my "+24V" rail will actually be around 23.5 V, which is fine for the stepper motor and downstream regulators.
The coils for relays K1 and K2 are operated via SW1 on the AC side. K1 toggles the Enable line on the sequencer X1, and K2 disconnects the stepper motor coils at shutdown to limit the current requirements (i.e., without this cutoff, if the device was switched off when the motor was drawing high current, C1 would drain quickly and kill the circuit before X1 had a chance to shut everything down properly).
X1 is shown as a block diagram element for the sake of brevity. I don't think its underlying schematic is important to answer my questions, but I can post more details if necessary.

Here are my questions:

Is my implementation of C1 an appropriate way to ensure the circuit has power after the main switch SW1 is flipped open?
If so, is the configuration of R1, R2, and D1 acceptable to limit the inrush current and protect PS1? I looked into using an NTC thermistor in lieu of R1, but I was concerned that the thermistor might not recover fast enough to avoid overloading the supply if SW1 was quickly cycled.
Assuming the proper relays are used, is it acceptable to have an AC input (SW1) operate DC circuits via K1 and K2? I've seen this configuration in some industrial equipment, but I wasn't sure how common it was.
Are flyback diodes necessary when K2 switches open the motor coils of M1, or are the snubbers on the H-bridge in the stepper driver U3 sufficient to limit the back EMF?

I'm also open to any other suggestions or best practices for a circuit like this.


texts: How to use photo interrupter to switch a higher voltage circuit

texts:
I have a circuit below, which is the internal circuit of a device that I'm interfacing with via a an ethernet port that is separate from the rest of this discussion. Via the ethernet port, I can see whether the gate from DI0 and DI COM is open or closed. I need to open and close the gate between DI0 and DI COM with a photo interrupter. Unfortunately I don't know the voltage or the circuit to the right of the screw terminals. EDIT: Measuring the voltage from DI COM to DI 0 without anything connected, I see a reading of about 6.6v. The input supply to this device is about 12v, so the resistor in this circuit may be dropping it from 12 to 6.6, we might can hypothesize the load on that circuit that way?

My photo interrupter has 3 pins: 5v, GND, OUT. When the IR beam is interrupted, I get 5v on the OUT pin.

I tried connecting the OUT pin to the base of a TIP120 Transistor, separated by a 2k resistor. To this same transistor, I tied ground to the emitter. To the collector of the TIP120, I tied the base of a TIP42G transistor, separated by a 2k resistor.

I tied the emitter of the TIP42G to the DI COM pin, and the collector to the DI0 pin.

I would expect that when the IR beam is interrupted, the gate would close between DI0 and DI COM. When the IR beam is uninterrupted, the gate would be open. (Maybe I have that backwards?) However, when I check the device, it reports the gate is closed no matter what.

I have tested the function of the device by manually connecting and disconnecting DI0 and DI COM.

Here's my circuit (note, I don't have access to anything to the right of DI0/COM):

What am I doing wrong? I'm in quite a bit over my head.


texts: Easy way to figure out a LED's Vf in order to pick an appropriate resistor

texts:
I was wondering what the easiest way to figure out a LED's forward voltage is, using measurement tools.  I know we can assume red LEDs to be around 1.8V - 2.2V, and that we have similar information for other LED colors, but I was wondering if there's a way to figure out without assuming that.

I purchased several LEDs that don't have a data-sheet with their specifications - so as an exercise I would like to write that information down. (I'm learning)

Most answers I see start by connecting the LED in series to a resistor, but I want to make sure the resistor is right before connecting it.


texts: How do I find specifications for this transformer?

texts:
I am trying to find out what transformer is it, one of standard or a custom one and what specifications does it how (i.e. power ratio).

How would I go about finding that out?

I do not need exact answer, but more of a methodology.

The input is standard AC 100-240V 50/60Hz and output is DC 12V9A (as is specified on the schematics).

Thanks.


texts: Having trouble synchronizing serial data from FPGA to python script

texts:
I have a Spartan 6 that's collecting some data I need to send over serial to a python script where it can be displayed on my PC.

This is actually the first time I've ever dug into serial communications (I don't count programming arduinos)

So I'm essentially specifying the data format myself from the FPGA which makes me think I should easily be able to sync this communication, but it seems a little more difficult than I thought.

This is my current approach:

The data I am sending is 16 bits long, and I assumed that I needed to send the start/stop bits manually, so my serial VHDL module just reads in the 16 bit value and concatenates like this:

output_vector <= '1' & din & '1'

From there, a counter just loops from 0 to 17, assigning the Tx line to the current index of the output_vector

So I am not sure if my assumption is correct here.  Do the start and stop bits need to be manually transmitted like this? And how does the receiving end know a start/stop 1 from any other 1 in the data signal?

Baud rate

The counter I mentioned previously cycles through at a rate of 195.3125 kHz, so I added 16 bits for data + 2 start/stop bits = 18 bits total.

195312.5 / 18 = 10,850.694444444

So in my python script, I set the baud rate to 10,851 as that is the nearest integer value.  Even so, I don't understand how the receiving end synchronizes up with the transmitting side so it is actually in line and gets correct data.

My python script is pretty simple:

import serial

def convert_to_ascii(text):
    return " ".join(str(ord(char)) for char in text)

ser = serial.Serial(12)
ser.baudrate = 10851

print ser.name

while(True):
    data = ser.read(2)

    print(convert_to_ascii(data))

I ultimately need some way of combining the 2 bytes being read into 1 single integer value, but I haven't quite figured that out yet either.  The script is receiving data, but I cannot verify it is correct at all.

There is also mention of some sort of Xon/Xoff transmission relating to software flow control in the user guide for my FPGA board (Digilent Nexys 3), but I really have no idea how to use that. I'm totally lost here on how to synchronize up this simple serial connection.


texts:
Drilling 300 holes in fibre board is tedious, difficult to do neatly and prone to snap bits. What simple methods and tools are available to the home user to drill PCBs effectively?

In my case it's only going to be used occasionally and then on a kitchen table. Apparently a Dremel won't be accurate enough.


texts: Term for/information about manufacturing a non-rectangular PCB?

texts:
I’m interested in getting my own low-cost PCBs made for a custom PC keyboard which will have a non-rectangular shape. Something like this shape:

I’ve checked the excellent price comparison site at pcb shopper, but I'm not sure of the term used for making/milling PCB's that are not square.

I’d just like to know the term used for milling a non-square shaped PCB. Is this something that all PCB fabricators will support?

I assume that I have to add a special cutting layer to the design. Is there a term for that layer?

Basically what do I need to look for to get a board this kind of shape made?

If it's too difficult/expensive I will probably end up cutting the boards myself.


texts:
as the Vds increases in an NFET, the channel is finally closed and the
  Id is constant and the channel is saturated

When the depletion region around the drain expands and the channel moves mostly to source (the drain is connected to a positive voltage and source is connected to ground) then doesn't it mean that the source and drain are now isolated (since the channel has moved away from drain) and Id becomes zero not constant?

I don't unedrstand it!

Another question: I would say depletion region is free of charge and there are only ions there which are not mobile so there are no mobile carriers in depletion region, but in my textbook there is a term in equations as "Qdep".

What does that mean?


texts: Finding the transfer function of an non-inverting audio op-amp

texts:
I am just doing some independent re-search for myself in audio amplifier (CHIP AMPS) such as the LM1875.

I want to learn more about how to compensate for audio chip amps and how their bode plot works and bandwidths, but in order to indulge on this I need to do some math to prove it to myself.

This is the LM1875 that I designed. Simply I want to just understand why C2 is used for as I have heard it's there to make your DC gain (22.2dB) flat among many frequencies which is true as shown here:

My idea was to make a transfer function of this op amp (Very simplify shown below) and just do a frequency analysis where s->jw and sweep it on the bode plot.

Here is my attempt:

Assuming this model now:

Node VA = The voltage between the cap and the resistor.

First Node:

\$ \frac{V_{IN}-V_{OUT}}{R_{6}} + \frac{V_{A}-V_{IN}}{R_{7}} = 0\$

\$ V_{IN}(s)*[\frac{R_{7}}{R_{6}}+1]-\frac{V_{OUT}(s)*R_{7}}{R_{6}}= V_{A}(s) (1)\$

Second Node:

\$ \frac{V_{A}-V_{IN}}{R7} + C_{2}* \dot V_{A} = 0\$

\$ VA(s)*[1+R_{7}*sC_{2}] = V_{IN}(s) \$

\$ VA(s) = \frac{V_{IN}(s)}{1+R_{7}*sC_{2}} \$

Sub (2) into (1)

\$ V_{IN}(s)*[\frac{R_{7}}{R_{6}}+1]-\frac{V_{OUT}(s)*R_{7}}{R_{6}}= \frac{V_{IN}(s)}{1+R_{7}*sC_{2}} \$

Which comes down to:

\$ H(s)=\frac{V_{OUT}}{V_{IN}}= \frac{6.11s+1}{0.470s+1}\$

Bode plot:


texts: What should be the output voltage for Virtual Ground to occur in Inverting OpAmps?

texts:
If I give 1v as an input to this inverting opamp, the output should be -10v just to make the difference between the input terminals 0. But when I solve the circuit using KCL for 1 volt input I get 1000v as output ?

here is my calculation:

Va= Voltage at inverting terminal Vo = output voltage,

let Va = 0 (due to virtual ground at inverting terminal);
(Vin-Va)/Rin = 10mAmps [that flows through input]
[this 10 mAmps should also flow in the feedback path since no current goes into opamp], so 10mAmps * Rf = 1000V across feedback resistor

so Vo - Va = 1000volts

since Va = 0 Vo=1000V output when I should have -10v at output for virtual ground (0v at Va)

can someone clarify ?

Also why is that we have a voltage divider between Rin and Rf for voltages other than Virtual ground at say inverting OpAmp terminal?

thanks.


texts: How to calculate signal propagation speed through vias?

texts:
There is a need to have a group of signals arrive simultaneously to their respective destinations, given that they start their journey at the same time.

However, due to physical constraints it is not possible to have them routed on the same layer, breaking routing symmetry.  In order to calculate their lengths so that flight time is equal, propagation times are needed. I have formulas for microstrip and stripline propagation speeds, but I don't have any for vias. Does anyone have any information about this?

PS:I am aware that nearby ground vias are required for the return path to find a way to switch reference planes.


texts: Can I use a voltage divider and/or voltage follower to produce 1V from 9V for an op-amp oscillator?

texts:
For a circuit I'm building, I'm using an op-amp oscillator to generate a sine wave. The sine wave will have a maximum voltage of 1V and a minimum voltage of -1V. The circuit will be powered by a 9V battery, and I already have a selection of chips to pick from for converting 1V to -1V. How should I regulate 9V down to 1V? I'd rather not buy a chip to do this, as I'm pretty certain that I have everything I need.

If I use a voltage divider (with resistors) to generate 1V, can I then feed that into a voltage follower to eliminate the loading effects? The page mentions that doing so will produce stability issues, so I'm not sure.

Thanks,

Edits

Some details about my oscillator:

It will be a sine wave
I need at least 8 kHz. In the range of 8 to 10 kHz would be fine.
I haven't drawn up the circuit yet, but I'm thinking of using a Wein bridge oscillator. I'll take other suggestions though, because I have never designed an oscillator before
Powered by a 9V battery


texts: How can I modify the charging circuit of the solar powered system using super-capacitor with or without battery (diagram is attached)?

texts:
I 'm working on a device which according to the below diagram, has a solar panel witch gives at most 10v voltage and 30mA current (average 9v and 20mA) and also it has a 6v lead acid dry battery with 3.2Ah capacity. The system (main circuit) works with 3.3v and draws in standby 1mA and depending on the task, 6 mA or 20mA or 100mA or 300mA, say 8 times a day.

I wanna add some super capacitors to the device to store energy when the battery is full or to reduce the number of charging cycles (for lengthening the life of battery) and probably to remove the battery and also I wanna use a switching converter for reducing the power loss in the device instead of linear voltage regulator.
Now my questions are:
1. Is the future circuit diagram is correct? Can 3 super cap.s be matched with battery in aspect of difference peak voltage that they will have?
2. Is the capacitance of the super-caps is enough to supply enough power to the system or we need the battery as well? Can we use a different, smaller, batteries from different type?
3. Do you have any recommendation for a suitable IC as DC/DC buck converter?
If you have any recommendation or comment regarding the this problem, please share it. Thanks.


texts: Fitting home made circuit on petrol scooter

texts: I have an old honda scooter which has bulbs in all lights. Also, they are driven by AC voltage. I made sequential led indicator circuits(four of them) using 74HC595. The working voltage of the circuit is 5V. The total current draw is less than what the bulbs take. Just that I will have to wire them to get DC from the 12V battery on the scooter. The voltage coming to the terminals of the battery will climb up to ~14V depending upon the RPM of the engine. I already have 7805 regulator and capacitors attached to the circuit. My question is: Is this voltage regulator all I need for the circuit to work without any problem? Or should I add anything additional for the safety of the circuit and the scooter other than fuses?


texts: How to accept switched GND or switched Positive on a 3v3 MCU input

texts:
I am making a device based on a STM32F105 (3v3) that has to accept inputs that I am not in control of, for example in a vehicle or other wiring that I cannot change.

The device is to have 16 inputs.

I want the input to be selectable between active low and active high. Because sometimes I might come across a switch that is switched to GND and sometimes one that is switched to say 30v.

All inputs have to be 30v tolerant.

I would like to have the option of selecting in firmware whether the input is connected to a switched Ground or switched positive.

How can I go about accepting inputs that could be switched GND or on other occasions be switched 24v?

For example I may come across either of the following so I need my circuit to be able to accept both:


texts: Is a resistor required to power a LED strip with a 9V battery?

texts:
I have a 7020 white light LED strip, which includes a resistor on each module as you can see:

I would like to power a little strip of five of these modules with a 9 V battery, but I wonder :

1- Do I need to put a resistor beetween the battery and the strip (so the leds do not catch fire or early die, or anything inappropriate)?

2- If I do, how many ohms do it needs to be?

EDIT :
The question is not about the intensity of the light that the LEDs can emit, nor about how long the battery will operate.

As the strip comes prewired and includes a resistor on each module, I suppose that this is not required, but I read everywhere that lighting a single LED requires a resistor upfront, and I can't find anything about how this applies or not to LED strips.


texts: Function to Determine Plunger Force on Solenoid Actuator

texts:
I am designing a solenoid actuator system and need help determining the kinematics. I need to know what the force from the solenoid would be as a function of the plunger's position.

Would there be a simple function or would it require more advanced FEA modeling algorithms to get a good answer?


texts:
This isn't anywhere near as true as it used to be, but I consider one difference between x86 platforms and ARM platforms to be whether or not booting involves the use of a mask ROM at reset to initialize the system. If we ignore the developments of Intel's ME and AMD's PSP, x86 processors start executing from EEPROM. The code that is stored there can be in whatever format because the processor just executes it, no questions asked. At reset on an ARM chip, things are more complicated. The CPU begins executing code stored in an on-die mask ROM and this code may or may not pass off execution to code stored in a mutable medium depending on the chip's design. The code that it'll jump may need to have a header, even if it is stored in a memory that is XIP-capable.

There are a few instances of ARM-based processors that will start executing code that is stored in EEPROM. The STM32 line of microcontrollers fits this design. However, there will still be some kind of read-only code on the chip that can be booted from if the pin configuration is right. On the STM32 chips there is an "embedded" bootloader on the chip that is used for programming the internal flash.

My question is this: do there exists ARM chips that lack any sort of boot ROM and will behave at reset in the same way older x86 processors used to operate? What situations would they be used in?


texts:
I was trying to measure the current of the AC line using CT. As I haven't used CT before, I thought that the output of the CT will be sinusoidal for a resistive load on the mainline. But the actual output was totally different from sinusoidal.

The circuit is simple. 220 volts main is stepped down into 24 volts and connected to 833-ohm resistance.

How can I measure instantaneous current using CT? Is it possible to apply any higher-order regression to calculate the instantaneous current? Not just the peak value. At least 30 samples per cycle. The CT used here is 5A/5mA.
Problem Solved
As @Andy said to insert a burden load, so I checked that. I connected a 220-ohm resistor to the CT. And the output was sinusoidal.


texts: Can I detect zero crossing on the transformer's secondary?

texts:
In this answer poster uses the rectified secondary's half sines to detect the zero crossings of the mains voltage. Can you do that? I thought there was a phase difference between primary and secondary, depending on the load.

edit
If there is a phase shift, can it be so big that it's unusable for detecting the zero crossing?


texts: Which is the best way to version control Xilinx PlanAhead projects?

texts:
Actually I'm migrating some mature projects from Xilinx ISE to Xilinx PlanAhead. I need to take advantage of TCL scripting and partitioning of PlanAhead.

This ISE projects are under version control in a SubVersion repository, so I need to define the files that must be under version control but in PlanAhead projects.

On one hand, this question talks about the files needed to put under version control to exactly re-create the implementation results. Even in PlanAhead 13.2 exist the command "File->Archive Project..." that save the sources and other project and option files in a ZIP archive, allowing us identify the files that must be under version control. This is the first choice.

But on the other hand, it is not clear that use this collection of files is the right way to manage a version control for a PlanAhead project. This xilinx forum conversation talk about using a tcl script to re-create the full project, but this script must be maintained apart when a new change is introduced in the PA project

Vivado (son of PlanAhead) have the XAPP1165 application note that talk about version control and recommend put the re-creation TCL script under version control, but Vivado can generate automatically this TCL script.

I would to know which is the best way to version control PlanAhead projects. Identifying needed files or maintaining a re-creation TCL script?

Thank you very much for your responses. Best regards.


texts: How are components typically connected to a PCB when they are mounted in an enclosure?

texts: Many small speakers are designed with screw holes to mount them in enclosures.  They also have connectors to solder wires so they can be electrically connected to a PCB.  How do I do something similar with a photoresistor?  I want to mount a photoresistor (PDV-P8104 as a random example) in an enclosure, then connect the terminals of the photoresistor to wires and connect the wires to the PCB.  How does one typically connect the terminals of a through hole component to a PCB when the component must be physically placed farther away from the PCB than the length of the leads?


texts:
I'm making a magnet which gets turned of and on by a pwm signal and a irfz44n mosfet. The problem is; //The magnet gets current even though I don't apply current at the gate.// I tried a lot of things like switching the connection and such but it won't bother.

Might the MOSFETs be counterfeit? I bought them from BangGood (Chinese site).


texts: Can packets be read out of the NRF24L01+ while in RX mode?

texts:
So the data sheet says that registers cannot be written unless the chip is in standby, however, this seems to suggest that the chip has to be taken out of RX mode to read a packet and clear the RX flags.

This seems a little odd since the TX side of the chip can send up to three packets back-to-back. If a chip TX'd three packets at once and the receiver started processing after the first, the other two would be lost since the receiver wouldn't be in RX mode when the next two arrived.

Is the data sheet overly prescriptive on this point? Is it possible to drain the RX FIFOs while staying in RX mode? Any hands-on experience?


texts: Replace Relay with NC Solid State Switch

texts:
I have an AC voltage source which runs at about 6V to maximum 70V (usually around about 14V @ maximum 8W) which is then rectified in a diode bridge rectifier and later regulated to stable 5V. From this 5V I run a microcontroller.
Depending on the AC voltage I want to either include more or less capacitance (C1, C2, C3) before the bridge rectifier. To do this I use SPDT relays which are switched from the 5V rail using the microcontroller.

Now what I would like to do - mainly due to size (or rather height) constraints - is to get rid of the relays since they are just way too large. My idea was to use two back to back MOSFETs (with the sources connected) to replace every relay. I could drive them with my 5V rail through an optoisolator (like the VOM1271). But this way I'd have a normally open switch.
How would I get this to be normally closed?


texts: What is the minimum amount of 1bit Full Adders required to implement the equation 4X + 3Y + 13?

texts:
Using 1bit FAs and 0/1 constants only, while X(x1,x2,x3) and Y(y1,y2,y3) are 3bit each.

It is possible to implement it easily with 7FA, and there's a solution with 6FA as well.

Is there a solution with 5 or less? If not, why?
Is there any systematic way to solve such problems?

This is how I break down the problem:

0  x1  x2  x3   0  0
0   0  y1  y2  y3  0
0   0   0  y1  y2 y3
0   0   1   1   0  1
====================
z1 z2  z3  z4  z5 z6

Here is a truth table I made for the problem.

Currently, I've got to the conclusion that:

z6 = ~y3
z5 = y2
z4 = ~(x3 XOR y1 XOR y2 XOR y3)

But I'm not sure how helpful that is.


texts: What material of a core put into the inductor would decrease the current?

texts:
Consider the \$AC\$ circuit:

For various \$U\$ values set by the potentiometer, we have measured the current \$I\$ flowing through the circuit with and without core put inside the inductor \$L\$.

As a result we concluded that, without the core, the current was always bigger than with the core.

E.g.: for set \$U = 4V\$ the current with the core: \$I = 4.33 \; mA\$ and without the core \$ I = 26.9 \; mA\$.

The cylindrical-shaped core was made out of metal-alike material.

Questions:

Given the fact that with the core the current was lower, what material could the core be made of? Ferromagnetic cores increase the current, right?
What exactly does the Atr in the schematic stands for?


texts: Why are there no high efficiency green/cyan phosphor LEDs

texts:
High efficiency (up to 50% efficiency) white phosphor LEDs are widely available They work by using a blue emitter shining through a green and red phosphor layer to convert some of the blue light to red and green. Why not make green/cyan LEDs in a similar way to white LEDs, except without the red phosphor?

A range different colours from blue to green through cyan. Could be made in this way by varying the strength or the phosphor.

Also if a cyan LED of this type was combined with a true red non-phosphor LED, the result will be white light. This white light source should be more efficient than the conventional white LEDs that uses red phosphor, because the red part of the spectrum is being generated 'directly'. True red LEDs are up to 70% efficient.


texts: A sawtooth oscillator breaks down at higher frequencies

texts:
Here is a nice and straight-forward sawtooth oscillator that I learned from this video.

It is simple and nice. When we come to higher frequencies though, I am dealing with very finicky adjustments that end up breaking down. I can reduce R3 and C1 to get the slope up, but that only works until a few-fold increase, and then I'm at the end. The R1 can be tuned a little, but needs to be 1k for higher speeds. And at some point the difference between 1.5k and 1.8k makes the difference between life (oscillation) vs. death.
Like, even setting C1 to 1nF, with that R1 of 2k, nothing works. Reducing R1 to 1k gets the oscillations back. But we're not at much higher frequency, actually, we're at lower frequency.
We can do C1 = 100pF and R1 = 1kOhm and get about 2.5kHz. But now we're beginning to have non-linear starts and ends of the sawtooth:

and from there it gets only worse:

is it the switching speed of the BJTs that's causing this non-linearitiy? I am surprised that it is happening at frequencies that are still pretty low. Here we are only at 20 kHz, i.e., even if I wanted to use this as an sawtooth for an audio use case (sound synthesizer) I am already stretched to get that right.
Is this circuit known for this limitation or is there some better way to scale it to higher frequencies that I just don't know?
UPDATE: I took the suggestion of using the two diodes instead of R1, and unfortunately it's flat-lining and I can't find a proper C1, R2 and R3 that would make it oscillate.


texts: Basic code to switch LED for PIC18f4550 C18 not working

texts:
Ok, I'm sure it's something stupid but this is probably the 20th variant of this code and I can't get it figured out.  I simply want a (debounced) switch to trigger an LED on the PIC18f4550.  Should I be using a different port for the switch?  Here's my code:

void main(void)
{

    TRISBbits.TRISB0 = 1;    //switch input
    TRISBbits.TRISB3 = 0;    // LED output
    PORTBbits.RB3 = 0;       // make LED low by default
    TRISEbits.TRISE2 = 1;    // alternate switch input

    while (1) {                       // doesn't work for some reason
        if (PORTEbits.RE2 == 1) {
            LATBbits.LATB3 == 1;
            }
        else LATBbits.LATB3 == 0;
    }
}

Tried to post the config code but it screwed up the formatting here.

EDIT:  sorry for the ugly formatting, but here are the config settings.  Had to change some things to keep the formatting from getting weird.

include stdio.h
include stdlib.h
include p18f4550.h
include delays.h

// chip config     ////////////////////////////////////////////////////////////////////////////////////

pragma config PLLDIV = 5
pragma config CPUDIV = OSC1_PLL2
pragma config USBDIV = 2

                               // internal clock, pin #14 (RA6) as I/O pin, pin #13 unused,
pragma config FOSC = INTOSCIO_EC    // if OSCCON is left as default clock speed will be 1Mhz

            // now the other less confusing options . . .
pragma config FCMEN = OFF
pragma config IESO = OFF
pragma config PWRT = OFF
pragma config BOR = OFF
pragma config BORV = 3
pragma config VREGEN = OFF
pragma config WDT = OFF
pragma config WDTPS = 32768
pragma config CCP2MX = ON
pragma config PBADEN = OFF
pragma config LPT1OSC = OFF
pragma config MCLRE = ON
pragma config STVREN = ON
pragma config LVP = OFF
pragma config ICPRT = OFF
pragma config XINST = OFF
pragma config DEBUG = OFF


texts: Why is a DC brushless fan always spinning in the same direction?

texts:
Computer type DC brushless fans integrates both a single phase DC motor and electronics to drive it (you only provide typically 12V or 24V and the thing rotates)
There are only two MOS and one hall sensor inside driving it, as it is for example explained here:
https://www.youtube.com/watch?v=Im2GoXVy8d0
I assume that the 4 coils are either "N S N S" or "S N S N", then I don't understand why this is always spinning in the same direction, since everything seems symetrical


texts: Using a Programmable Switch w/ 3.3V Logic Level to connect capacitor load with varying input

texts:
I am trying to connect the output of a Digitally Programmable Step-Up Boost Converter (TPS61045) with a capacitor through a switch. Basically when the boost converter turns on it turns on at the median value. So I need to turn on the boost converter, send commands to lower the voltage to the minimum voltage (~3.6V). And then turn on the switch to connect the boost converter output to the capacitor to charge it. Then I ramp up the voltage of the boost converter to 19V. The purpose of this is to reduce the in rush current on the battery powering the boost converter by ramping the voltage in 64 steps. I'm also looking for a load switch to then discharge the capacitor onto a resistor after the capacitor is fully ramped to 19V.
Does anyone have any ideas of what switches to use for this application? I was looking at integrated load switches but tried using one (FDC6326L) and it wasnt working well.
I want to control the load switch with an arduino 3.3V logic level.
I was working with Power Relays for a bit but want to move towards FETs.
Thanks,
EDIT: I'm using 4 100uF multilayer ceramic caps that reduce by about 35% in capacitence when charged to 19V


texts: Does the noise voltage formula apply even if the impedance is not matched?

texts:
Does the thermal noise voltage formula: \$ V_n=\sqrt{4kTBR} \$ apply even if the impedance is not matched, or is the noise power formula of \$N=kTB\$  the one that applies even if the impedance is not matched? (k=boltzmann const, T=temp, B=bandwidth.)
I'm confused if the thermal noise voltage formula was derived from matched impedance using the noise power formula or the other other way around: noise power formula was derived from matched impedance using noise voltage formula.


texts: Can UPDI Enabled AVRs be Programmed at 1.8V?

texts:
Microchip's new line of Tiny AVRs use the new UPDI programming interface.

After looking at the datasheets for the ATtiny817/1617, the Atmel ICE interface document, and the internet, it's still unclear whether these new devices can be programmed/debugged @ 1.8V.

Has anyone attempted 1.8V UPDI programming/debugging, and did it work out of the box?


texts: Need help with SD Card Initialization (CLK Syncronization)

texts:
EDIT 1 : I made changes to the code as @Anonymous suggested in the answer. It seems to have improved but now I seems to be getting incorrect response OR SD CARD putting response at the wrong time.

The logic data file after making changes as Anonymous suggested in the answer

I am trying to bitbang SPI interface for the sd card. I was at first confused regarding the mode to be used. so I asked regarding the SPI Mode over here.

I am initializing my CLK as Output with internal pull up and driving low. Same goes for the MOSI. while MISO is Input , Pull up and nothing driving that.

Here is my SPI Send and Recieve.

int spi_bb_send(spi_bb_config_t *spi_conf,unsigned char data)
{
  int i;
  uint8_t data_in = 0;

  // send bits 7..0
  for (i = 0; i < 8; i++)
  {
      spi_pin_clear(&(spi_conf->clk));

      // consider leftmost bit
      // set line high if bit is 1, low if bit is 0
      if (data & (1<<7))
          spi_pin_set(&(spi_conf->mosi));
      else
          spi_pin_clear(&(spi_conf->mosi));

       data_in <<= 1;
      data_in |= gpio_read(&(spi_conf->miso));

      Delay(SPI_TIME_IN_US(SPI_FREQ_KHZ));

      // pulse clock to indicate that bit value should be read
      spi_pin_set(&(spi_conf->clk));
      Delay(SPI_TIME_IN_US(SPI_FREQ_KHZ));

      //read the miso
      //data_in |= gpio_read(&(spi_conf->miso));

      // shift byte left so next bit will be leftmost
      data <<= 1;
  }

  Delay(SPI_TIME_IN_US(SPI_FREQ_KHZ));
  spi_pin_clear(&(spi_conf->clk));

  return data_in;
}

int spi_bb_recieve(spi_bb_config_t *spi_conf)
{
    return(spi_bb_send(spi_conf,0xFF));
}

The initialization command have been tried as per Physical Layer document provided by SD ORD i.e following this initialization flow.

As well as the initialization flow I found from this Answer regarding initialization flow.

The issue I am facing is I am getting the command and response for the 1st two commands correctly that is CMD0 and CMD8 and I am not facing any issue no matter how many times I try. When I send the third command i.e :

1) CMD58 as per the SD Org document , I dont get any response back.
2) CMD55 as per the person's answer on this SE, I seem to get correct response but the reponse I read get's an 0xF before the reponse so I believe that SD Card starts reponding from halfway of the clock generated. So I hooked up logic analyzer to it and here are the results.

Command 55 :

No Response on the first clock :

Response :

There is some insights given on the link to answer pasted above that say :

  Note that responses that have the MSB set but ain't 0xFF usually suggest that your SPI got a shift in clocking (as a result of e.g. Vcc drop, which happens routinely when you're doing SD hotplugs). To fix it, you can try to completely reset the device (power on/off, deassert/assert S̲S̲ etc.); it usually works.

But I am not doing any hotplug and neither resetting / power cycling works, So can anyone help? Please?


texts: Flyback simulation - not regulating at lower load

texts:
So I've been trying to simulate a flyback converter with the full load condition of 10v, 10A (100W) at the output at fs = 80kHz. The design equations I used were from "Pulse-Width Modulated DC-DC Converters" by M. Kazimierczuk.
Given that my input range is from 180Vrms to 230Vrms, I wanted the flyback to regulate the output at 10V from 0 to 10A.
My simulation circuit is shown below.
My output voltage is shown below for both 1ohm load and 100ohm load. 1ohm is to simulate the 10A output while 100ohm is to simulate a much lower load (0.1A).

Since V1 is supposedly from the controller IC and there is no feedback here yet, it is an open loop system. I basically adjusted the duty cycle of Q1 gate signal to get my desired output. 325v at the input is assumed to come from the previous rectifier stage with 230Vrms input (high line). At full load (10A), duty cycle is around 30% to achieve voltage regulation (10v). But at 0.1A output, I can't seem to regulate the output, even if I drop the duty cycle as much as I can. The output waveform I've shown for 0.1A has a gate signal for Q1 with 5% duty cycle.

L2 was the magnetizing inductance, and since I want to design the flyback in DCM, I calculated that Lmax = 546.4uH. Anything higher than this can possibly make the flyback operate in CCM. So I chose Lm = 500uH. L1 was just there to simulate some leakage inductance.

The number of turns n = N1/N2 = 16.78. So I chose 17 in this case. The mosfet and diode are chosen such that their ratings are higher than my calculated max current and voltage across them.

Any suggestions on where do I start to fix this?


texts: How to select an inductor for 3rd overtone oscillator SIMPLIFIED way

texts:
My question is at least approximate calculation of L1 inductor. With my design I have followed below SIMPLIFIED rules. Can someone correct any of my mistakes, if my component selection is proper? Crystal I plan to use is 27MHz load capacitance 9pF, frequency I desire is about 81MHz. I have only small space available on PCB.

I have seen in literature from Analog Devices, that C3 capacitor can be safely selected with a fixed value of at least 10 times the value of C2 capacitor and it should be ceramic NP0 material. In my case it should be above 180pF.

C2 should be same as C1, and about double of Xtal load capacitance.
In my case 2 * 9pF = 18pF.

L1 should be tuned with C2 to about 2/3 of 3rd overtone frequency, which is in my case about 54MHz. The simplified calculation ignoring stray capacitance etc is:
2/3 final frequency = 1 / (2*pi * SQRT(L * C))

L1 should be better quality, at least Qmin = 30; Rl < 1 Ohm; SRFmin = 100MHz

My schematics at this point is:

Your advice is very appreciated.


texts: How to generate an impulse to test a system's impulse response

texts:
I just started learning some basic control theory to better understand how a transfer function is constructed from a circuit and how a system is characterize by a function.  In it I found analyzing a system regularly uses singularity functions such as impulses and steps, and by operating on the superpositions of these functions, we can make the math easier to calculate.
Now I am so sunk into the math that I can't relate these math operation to reality. If I'm given the equation for an input function \$ x(t) \$, an system function \$ h(t) \$ or operator \$ H \$, I could probably calculate the output \$ y(t) \$. All these calculations utilizes an ideal dirac-delta impulse, in multiplication or integration with a superimposed element of an equation.
In practice, how can I produce such an impulse to couple with part of the signal? Do I use the pulse function in a function generator to approximate an impulse? Or people short their circuit (e.g. shorting and discharging a large capacitor) to approximate a dirac-delta impulse to see how a system response?


texts: Why do fundamental circuit laws break down at high frequency AC?

texts:
We're just starting the whole RF scene having dealt with DC and low frequency AC for all our previous courses.

I understand that at high frequency AC, fundamental circuit laws don't apply anymore and the classic passive component models need to be changed. The justification for this was that at high frequency AC transmission, the wavelength becomes much smaller and can sometimes be smaller than the wiring on PCBs etc.

I understand that this is an issue when transmitting through free space with electromagnetic waves but why is this an issue with actual physical wires and PCBs being driven by an AC source? I mean it's a direct connection, we aren't using electromagnetic waves to propogate through free space and so wavelength and stuff shouldn't matter right?


texts: Onkyo subwoofer amp, disable automatic power toggling

texts:
I have this subwoofer that turns on and off based on if there is signal on the input. It's real annoying that I will be watching something quiet, it will turn off, and then later it will turn on again when something happens with bass. It takes a couple of seconds to kick on, so it misses what it supposed to come through the woofer.

I have a schematic. I have no idea on where to start. I cannot grasp when there are like a dozen transistors and they all interact with each other and pull things to ground or VCC. I tried removing Q901 and installing a jumper to ground...to no avail. No idea what I'm doing. Thank you.


texts:
I am trying to feed a 5V signal to AD7705 which is a 16 bit ADC and expects differential inputs. Do I need to divide my 5V signal using bridge and then feed it to the ADC or can I use it as a single ended ADC.

What confuses me is the need of Vref as 2.5V. I understood that the differential inputs don't need and Vref as the inputs are compared in respect to each other.

If I do need to split up my signal, then I assume a four resistor bridge of same values should give me center tapped output to feed into the differential inputs.  What standard grade "R"values should be selected? The ADC has a buffer in built, thus input impedance is not much issue, I guess.

Datasheet link:http://www.analog.com/media/en/technical-documentation/data-sheets/AD7705_7706.pdf


texts: How to design pre amp for a condenser studio microphone

texts:
I've bought a condenser studio microphone that connects to my computer.
It looks like this:

Unluckly it's too quiet and actually can't make any recording without boosting it's sensitivity in Windows (but the audio will suck.) I designed a pre amp for it.
The problem is I actually don't know how to connect the microphone to the amp then to my PC.
On the bottom of my microphone there is a 3 pin XLR connector, but the microphone came with an adaptor cable that transforms that XLR conector into a 3.5 mm jack.
The only thing I know is that pin 1 and 3 of the XLR connector are connected together through the adaptor cable to the sleeve of the 3.5 mm jack and pin 2 of the XLR is connected to the ring and tip of the 3.5 mm jack
I'd like to know how I would connect my microphone to the pre amp and the pre amp to my computer.
I've also added a schematic of my pre amp.


texts: Obtaining timing score of a implementation run with a PlanAhead TCL script

texts:
In a PlanAhead TCL script, I need to know the timing score of a completed implementation run.

I have found an old way to do this from 2012. The solution is read directly the PAR report file.

In Vivado exist the TNS property that can be read directly with the report_property command. It exist a similar (and cleaner) way to obtain the timing score in PlanAhead?

Other options to obtain the timing score?

Best regards


texts: Why does physically touching a specific pin eliminate circuit issues?

texts: This is a strange question and I don't know if I will be able to describe it correctly. There have been several instances working with a system that basically consists of a board camera, an FPGA, and TFT display where I can eliminate image noise by physically touching a specific wire or pin. For example, the current system I'm working on has pretty strong red noise in the live camera image. If I specifically touch the CAM_DATA[7] pin (the MSB for red), the noise disappears. It also disappears when the oscilloscope probe is connected to that pin, but not when the ground clip is attached. What effect does a person touching a specific wire/pin have on a circuit and how can I reproduce this "solution" with a basic components? ( I have verified that the issue is not just a loose wire or loose connection that is coincidentally going away because I'm pushing on it.)


texts: Why OR gate outputs 1 in my proteus simulation?

texts: I build a simple circuit in proteus, but it doesn't work as expected. I have no clue what happened. Here is my circuit diagram.


texts: Why does my variable power supply have both a current limit and an overcurrent protection mode?

texts:
I have a benchtop power supply (it's not in front of me right now, so I can't say the model, sorry) and it has a current limiting mode enabling it to operate as a current source.  However, it also has an "over-voltage" and "over-current" protection mode (OVP and OCP, respectively).  Once either OVP or OCP trip, the supply stops providing any power.

My question is: why do those protection modes exist if I can just set the limits on current and voltage myself?  Presumably, if I know what to set the protection modes to I'll know what to set the limits to, so what's the point?


texts: Instead of grounding myself with a bracelet, can I wear rubber gloves? Will this prevent any equipment I touch from getting shocked?


texts:
I usually only become a passive reader in this forum, but today I decided to ask my first question.

How many logic gates required for a 4-bit Carry Look Ahead adder and Prefix adder?

I know that Carry Ripple adder required 5 logic gates because it's basically a series of full adder.

However, when I looked up on internet for CLA and Prefix there are variety of answers that make me confuse instead.

Any answers or comments will definitely help me. Thanks!


texts:
Want to start by saying I'm a mechanical/aerospace engineer, and I'm fairly out of my depth here. My current project is on a load-testing rig. Ultimately, it will use a Honeywell HG1120 IMU to give the location/orientation of a test article. I have so many questions that it's hard to know where to begin, but I'll start with a couple basic ones:

1) The table below shows the connector pin description (as a side note, the document doesn't give a pin schematic, would it be safe to assume 1 is in the upper left, increasing in number to the right?). I have read that I need to connect voltages to both pins 11 and 12 for power, but seeing no VSS, do I need to decouple these with any grounds (frankly, I'm not even sure what that wiring should look like).

2) What does the PWR_RTN (Power Return) pin refer to? Do both of these pins need to be wired, and to what?

3) Given the choice between SPI and RS-422, which would be more "user-friendly" to implement on a PC with LabView?

Any help at this point is appreciated, but the simpler terms the better (at least giving me a direction to learn in).

Edit: image of the unit's connector. I have a breakout board that I can use to wire to a plug for a PC. That's another thing I need to figure out.


texts: Why earth pin in plug is larger than the other pin?

texts:
Why main line pin is not bigger ,the work of main line pin is more important than earth line?
And the flow of electricity is also pass through main line and neutral pin then why earth pin is larger than the other pin?


texts:
Please guide me select best suitable Near filed probe for my application out of these two.
Which will help to troubleshoot the EMI problem.
My Product Need to be compliance in range 150Khz -30Mhz for Conducted Emission, and 30Mhz to 1Ghz for radiated Emission.

Will near filed probe also help to identified Conducted emission problem or its only helpful for Radiated emission
When to use E filed probe or when to use H filed Probe

Thanks


texts: Difference between low signal and no signal for a SR latch?

texts:
I am struggling to understand how the SR latch works.

When an input has designation 0, this means "low signal" correct? Is this completely different than "no signal"? Doesn't a logic gate need some kind of signal in both input wires in order to produce an output signal?

If so I don't understand how an SR latch can ever product any kind of output. Even if we sent signal in through S and R at the exact same time, neither gate can produce an output until the other input on each gate receives a signal, but both gates rely on each other for those inputs, so...?

At the same time it can't be "no signal" either because this would imply the NOR gates could send a signal even when no power is being sent through.

Where is my understanding wrong?


texts: Modify generic chinese LED driver circuit

texts:
I have a lot of LED flashlights and lanterns from China that use a simple IC as their driver to get these different light modes. For instance I have this small keyfob lamp that lights in the following modes when the momentary tactile button is pressed - (High mode -> Low mode -> Blinking Mode -> Off), and yes I have to cycle through all modes to turn it off. Additionally long pressing the button will make it go into an SOS flasher mode.

I opened up the lamp and took a close look and found there only a total of 4 components, the LED, a momentary switch, a 3R0 smd resistor and finally a SOT23-6 type IC with “2819” written on it. I googled for that IC and found it’s FM2819 by “Shenzhen Fuman Elec” and found it’s datasheet too. The circuit used in the lamp is exactly the same as the one shown in the datasheet.

What I want to know is that is there any way of modifying the circuit/wiring to get rid of all these light modes? since all I want is just plain ‘ON’ and ‘OFF’.

SW in the circuit is for switch.


texts: Particular JTAG to program/debug MCUs from different companies or architectures

texts:
Althougth I never used one, I know JTAG is a standardized way to program and debug MCUs. But I see a lot of JTAG from various companies. Can I use a particular JTAG to program/debug MCUs from different companies and with diferent architectures?

For example: can I use a JTAG to program/debug STM32 and LPC micros? (all Cortex-m3) Can I use the same JTAG to program/debug MSP430 micros? (16bit MCU from TI)

Which JTAG do you recommend to buy? And why?


texts:
Using avr-gcc 4.8.0 and avr-libc 1.8.0 on Arch Linux. Trying to get UART RX interrupts working on an ATtiny2313 with this simple code which should echo the received byte:

#define F_CPU 14745600

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

#define USART_BAUDRATE 9600
#define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1)

int main(){
  DDRD |= _BV(PD6);

  UCSRB = (1 << RXEN) | (1 << TXEN);
  UCSRC = (1 << UCSZ0) | (1 << UCSZ1);

  UBRRH = (BAUD_PRESCALE >> 8);
  UBRRL = BAUD_PRESCALE;

  UCSRB |= (1 << RXCIE);
  sei();

  for (;;){
    PORTD ^= _BV(PD6);
    _delay_ms(50);
  }

  return 0;
}

ISR(USART_RX_vect){
   char b;
   b = UDR;
   UDR = b;
}

I upload this with avrdude and the LED fails to pulse. If I comment out the ISR, it works as I'd expect it to. UART polling also works normally, so I'm quite sure that it is configured correctly. I've been able to reproduce this with an ATmega162 and an ATmega328p.

Other strange behavior: if I compile without optimization, the LED will pulse until I send a byte, then it stops pulsing.

I've really got no idea where the problem lies as every tutorial I've seen uses almost this exact code.


texts: How can an electric motor car have a turbo?

texts:
I am not familiar with all the different vehicles on the road nowdays but I have read descriptions of electric vehicles. i.e ( EV) that are turbo powered.
How can an EV  be "tubo" when turbo refers to increased pressure? The concept of pressure has no meaning for EV. Perhaps the question is off topic and not condidered a question about electricity.


texts: stm32f103 I2C Bare Metal Programming Question

texts:
I am trying to send a simple data from STM32f103 to another one. But I am having trouble with my code. I have been working on it since 2 weeks and I couldn't find any solution. I am using PROTEUS to simulate and KEIL to compile.

according to data sheet, after start event SB bit is set in SR1 register. To test this I placed this code:

while( !(I2C1->SR1 & I2C_SR1_SB) );

But it stucks inside the loop. Can someone help me please? Thank you for reading.

And Here is my main function.

int main(){

clock_init();

//GPIOB clock enable,AFIO enable
    RCC -> APB2ENR |= RCC_APB2ENR_AFIOEN | RCC_APB2ENR_IOPBEN;
//I2C1 clock enable
  RCC -> APB1ENR |= RCC_APB1ENR_I2C1EN;
//Pin B6 , B7 alternative function open drain enable, GPIOB other CRL pins output and 50mhz
  GPIOB -> CRL   |= 0xff333333;

// reset the I2C1 peripheral
RCC->APB1RSTR |= RCC_APB1RSTR_I2C1RST;
RCC->APB1RSTR &=~RCC_APB1RSTR_I2C1RST;
I2C1 -> CR2 |= 0x08<<0;  //8mhz freq[5:0]
I2C1 ->CCR  &= ~(1<<15); //clear bit 15 to 0 (to have Standard Mode)
I2C1 ->CCR   |= 0x0028;
I2C1 ->TRISE |= 0x0009;

I2C1->CR1 |= I2C_CR1_PE; //peripheral enable

I2C1->CR1 |= I2C_CR1_START; //Start bit set

while( !(I2C1->SR1 & I2C_SR1_SB) );

GPIOB -> BSRR |= 0x0000ffff;


texts:
I have been designing a usb device using a psoc 4L with integrated USB full speed capability. Yet for nearly all of my designs as soon as I plug the usb into the computer I get the following problem.

From the research I've been able to dig into, this suggests that there is something wrong on my physical layer (I'm using a generic starter project provided by cypress, and occasionally I have had it correctly connect)

I've measured the D+ and D- lines and here are the pictures from my o-scope

My question is what appears to be the problem here?

My intuition suggests that D+(the blue trace) is taking too long (18 ns which is greater than 12 ns allowed) Therefore it has too much capacitive loading and I need to identify in the layout what could be adding to it. Is this correct intuition, or is something completely different going on?

EDIT *******

I redid the scope with measurements on. here it is. Looks like the voltage is consistently around 4.1V

EDIT # 2*******

I got it to work! I was originally powering the psoc 4 off of the miniprog. As soon as I switched to USB powered it worked. I'm talking with some cypress FAE's so as soon as I get an answer as to why that would be the problem, I'll post here


texts: TI LM3488 SEPIC, adjustable power supply down to 0 volts

texts:
I decided to make an adjustable power supply with input voltages from 3 to 6 volts (4A), and output voltages from 2 to 12 volts. But I had a thought, that as long as I'm making it, I should make it go down not just to 2 volts, but as low as possible, as close to 0V as possible.

I would also like to controll current. Currently it is controlled by the fixed Rsn resistor.

I decided to use LM3488 in SEPIC configuration.

(1) How to make the output go down to 0V?

(2) How to controll current with a pot or something similar?


texts: Problem with closing high side P mosfet using B type amplifier

texts:
I am using this high side P mosfet dirving circuity:

My problem is the main P mosfet doesn´t deactivate entirely. More specificly its gate is at 8,4V (with 15V vbat voltage it makes 6,6V gate - source diference => mosfet is activated [it shouldnt be in this state when Q1 is deactivate]. When I activate Q1, P mosfet is activated too and everything seems working.
Also I find out that complementary BJT´s gate is also at 8,7V.
My first suspicion was D1 (zener diode), but when I removed it, nothing changed.
Next I tried pull main P mosfet´s gate dircetly to VBAT to try if it isnt damaged. When I done that the mosfet deactivate => so mosfet is working.
I also tried to remove complementary BJTs to see if there isnt anything else pulling its gate to 8,7V, but after its removal complementary BJTs gate rised to VBAT, so there isnt anything else pulling it down.
I also tried to use higher VBAT voltage, but gate was still on something about 8V.
Do you have any idea whats forcing the complement BJTs to stay at 8V and therefore not deactivating the main P MOSFET?


texts: I bought a choke made of litz wire. The wire is enameled all the way to the ends. How does one go about stripping this wire?


texts: How to remove Black cooling paste on IC?

texts:
I am trying to reverse engineer a product, but I ran into a problem:

One IC had a heatspreader on top of it.

With a bit of force I could remove it, but I am unable to read what's written on the IC, because there is some kind of black cooling paste on it.

It's solid - I can only scratch it with a screwdriver. But I'm afraid that I'm destroying the text on the IC.

Do you have some idea what it could be and how to remove it?

It is probably a stepper motor driver, but I want to know which.

If it could help you, I can measure some voltages or watch it with an oscilloscope if you want. The whole circuit is working fine.

It is a DIP-16 with the Stepper motor connected to pins: 6-3-14-11
Pins 4-5-12-13 are connected to ground.
Pin 8 is the only other big Trace on the IC, guess that's VCC then.

I hope you can help.


texts: Should I use a parallel or serial connection?

texts:
I need to split one power cord from the wall socket to power three 20w lamps.

Should I use a parallel, or a serial connection?

Follow up question: In which ever case, where can I find some guidelines for how to proceed?


texts:
There seems to be conflicting information on the internet.

Are super capacitors polarized?  For instance, could you charge them and then suddenly invert their polarity (à la charge pump)?


texts:
I am looking to charge my iphone using a thermoelectric power generation device. The thermoelectric generator device has positive and negative leads, and I have tried connecting the wires from the USB cable (which I cut open and spliced) directly but no luck. I AM NOT LOOKING TO USE THE USB AND PLUG IT INTO A WALL/COMPUTER.

The thermoelectric generator device produces about .5 Watts and 1 amp.

Is it likely that the phone is not charging because the power supply is too low? Or is likely that the wire connection is poor? Does the power supply have to supply 2.1 Amps and 5 Volts for the phone to charge?

Thanks.


texts:
So I am working on a project for which I am using a USB Type C Receptacle for the main hardware interface.

I am familiar with the previous USB types and how their pins are laid out, however, upon looking up the pinout for USB Type C, I cannot figure out which pin corresponds to traditional, pins for USB Type A.  Does D+ / D- correspond to the traditional Rx / Tx, or does it have to do with the Rx+/- and Tx +/-?  Furthermore, which pin corresponds to the ID pin in microUSB B.

Any clarification is appreciated.


texts: SPI communication between Arduino Nano and ATTiny24

texts:
I'm trying to make communication between Arduino Nano and ATTiny24 using SPI. I've written code for master(Nano) and slave(ATTiny24)(with great difficulty)  but no luck getting the proper output. I'm transmitting '1' on both sides for simplicity. Here's the code:
Master code (nano):
#include<SPI.h>
#define SSpin 10
void setup (void)

{
  Serial.begin(9600);

  SPI.begin();
  SPI.setClockDivider(SPI_CLOCK_DIV16);
  digitalWrite(SSpin,HIGH);
}

void loop(void)
{
  byte m_send,m_receive;
  digitalWrite(SSpin, LOW);
  m_send=1;
  m_receive=SPI.transfer(m_send);
  Serial.println(m_receive);     //should print 1 here but it prints 255 always
  delay(1000);
}

Slave(ATTiny24)
int data;
void setup()
{
  DDRB=(1<<PA5)|(0<<PA6)|(0<<PA4);
  USICR = (1<<USIWM0)|(1<<USICS1);
}

void loop()
{
  data=slaveSPITransfer(1);
  if(data==1)
  {
    digitalWrite(PA1,HIGH);
  }
  else
  {
    digitalWrite(PA1,LOW);
  }
}

uint8_t slaveSPITransfer(uint8_t val)
{
  USIDR = val;
  USISR = (1<<USIOIF);
  while (! (USISR & (1<<USIOIF)));
  return USIDR;
}

Any help will be appreciated.


texts: Connecting Electret Mic to MT8870 Decoder Module

texts:
I'd like to connect the audio output of an Electret Microphone to the audio input of an MT8870 decoder module, which uses a 3.5mm stereo cable.

I plan to power the mic at GND and VCC pins and connect the AUD signal to the right and left channel of one of the jack plugs on the stereo cable.

The mic has gain of ~60V/V and I'm not sure if this would be ok or too loud for the input of the MT8870. Can you please advise? Thanks.


texts: How to regulate temperature of an IC/PCB -in a vacuum

texts:
I have to regulate the temp of an IC. (70deg. C)
The part will be in a vacuum chamber.
Electrical connections can pass in-out of the vacuum chamber through a port (plenty of connections available.)
I have done this before in air using TECs to regulate the temperature (both heating and cooling) using a control loop with a thermistor for sense feedback.
I am predicting this won't work in a vacuum.
TECs only create a temperature differential.
You need a constant temperature reference to go up and down from (like a chunk of metal with fans.)
If that chunk of metal cannot thermally conduct to air it will continue to heat-up.
TECs are not 100% efficient; a portion of the input power goes directly into heating the system, regardless of what direction it is being driven.

What I need to do is take thermal energy out of the system.
I don't think it is impossible.
Imagine a cylinder filled with air compressed by a piston, sitting a vacuum.
It takes a constant force for the piston to maintain position.

Compressing the piston further would heat up the cylinder (energy-IN)
Decompressing the piston would cool the cylinder (energy-out)

But even this example wouldn't work forever because of the friction losses from the piston actuating.
You need to thermally conduct in-out of the vacuum chamber.
But can you do this with electronics?
Would it be a TEC across the vacuum chamber barrier? If so, I don't have that.


texts: Why am I seeing more inductive spikes from my motor at a higher duty cycle?

texts:
What is the mechanism that causes more inductive spikes with a higher duty cycle, even if the frequency of the pwm is held constant? Doesn't the motor create voltage kickback only when it is turned off? If that is the case increasing duty cycle doesn't increase the frequency of the motor turning off(since PWM frequency is constant) and so should not increase motor spikes.

I am observing the PWM signal on a scope, and the spikes are more frequent and of larger magnitude. This is my setup:

The left portion of the circuit controls the duty cycle of the pwm, which is generated on the out pin.


texts: Need help identifying this fuse resistor

texts:
(hobbyist here, go easy :P)

Due to a loose wire hitting something, I busted my 12v 3.2amps 38 watts PSU and the magic smoke came out. Apparently a fuse popped and I want to replace it. I don't know what it is and after some research on Google, I can't find it. I always come across 4 or 5 bands color charts. Never 3.

I have a second working unit exactly the same. Without any load I measured the resistance at 0.9 ohms (my DMM only goes down to 200 ohm resolution so it may be not super precise).

When powered on, and with a small load of a couple of milliamps, there is no AC current drop and no DC current drop across it.

Here are some pictures:

Thank you very much!


texts: Is it possible to boost current into a load without boosting voltage also?

texts:
If a device "D" requires X watts power, and I have a power source Y that is less than the nominal voltage recommended by the device "D", can I obtain the same performance for the device by somehow boosting the current such that Y·(boosted current) = P?

I know this is a very simplified question that doesn't take alot of factors and practical limitations into account, but rather than getting an answer to my specific problem I would like to see the idea generalized.
If this can't be generalized, maybe some rules of thumb could be given along with some edge cases where it does not work could be helpful. Note that I won't have any issues with too high current burning out the wire(awg size can be adjusted). My main issue is that I do not have a high enough voltage as the device recommends and wanna know how much I can underpower and still get satisfactory performance.


texts:
I'm creating power supply for controller that usually operates with very low power consumption, but sometimes needs high power. To make the situation harder there is "sometimes" external power present (mostly not). So the whole circuit must live from super capacitor.

The problem I have is that I do not know how to replace the 7 ohm resistor on left side with some 'intelligent' circuitry that will primary power the controller and use ONLY remaining power to charge super cap.

Controller works in two modes (using 2 to 5 V as input voltage):

low consumption mode taking 1 uA to 20 mA (peaks of max
30 ms and minimum 5 s apart, usually few hours apart).
High power mode consuming cca 200 to 800 mA, before entering this mode the controller switches on the main supply and checks if input voltage is more than 3.5 V, should the voltage be below the controller waits with mains on in low power mode and resumes high power operation when input is over 3.5 V

There is also push button for cold start, but normally should be not needed as in case the controller recognizes less than 2 V on input (shortly before dying) it switches the mains on, so as soon as mains will be present the operation will be resumed automatically.

Now the problem in detail: There is 7 ohm resistor that is 'necessary' as the super cap will burn the 5 V power unit on cold start. But on the other hand it prevents high power operation of controller as there is not sufficient power for the controller (big voltage drop). For this reason I need to replace the resistor with something that consumes 0 A (real 0 or less than e.g. 1 nA) in case there is no external power. In case there is external power it should primarily power controller, if there is any remaining performance of the power source it should be used to charge the super capacitor.

Any ideas how to create this kind of circuitry? Thans for any help.

Until now I was trying to use transistors to monitor voltage difference between cap and power source, but this is not sufficient (and has high power usage when no external power applied (10 uA) depleting the super cap too fast.

Block schematics below.


texts: How to determine overflow from an adder/subtractor?

texts:
I suppose in binary addition (no negative numbers), overflow happens when theres a carry out?

Then for subtractor (2s complement), how do I determine it? From my understanding of my lecture notes, overflow happens when theres a change in sign or carry in of MSB is different from carry out? Is that true?

Then suppose \$011_{2s}+001_{2s}=100_{2s}\$ the answer is correct, but carry into MSB is 1 but carry out is 0, so according the the rule above, its an overflow?

  11
  011
+ 001 (2s)
=======
 0100

Suppose \$X\$ & \$Y\$ are my sign bits, \$S\$ is my MSB generated and \$C_{in}, C_{out}\$  are my Carry in & out. I will implement Overflow, \$O\$ as

Suppose the above were correct, I will implement the logic to determine an overflow like
$$Overflow = (Sign 1 \odot Sign 2)(Sign 2 \oplus Carry Out) + (Carry In \oplus Carry =Out)$$


texts: Can a square wave generated using an astable NE555 be used as input of a transformer instead of AC? Say, I generate a square wave of 60Hz using NE555 and a 24V at 6A supply and feed it into a transformer with 50:1 turns ratio, will I get 0.48V at 300A out?


texts: 555 timer that does not output low when reset

texts:
I'm trying to design a circuit with the following goals:

When not active, output can be either Vcc or floating
When triggered by pressing a button, output pulses several times to GND at some frequency F for a duration of N seconds
After the N second duration, the pulsing stops

My first thought was to use two 555 timers: one configured as a monostable timer with period N, triggered by the button. The output of the monostable timer is connected to RESET pin on a second 555 configured as an oscillator with frequency F. The output of this timer would be the desired output.

This design achieves goals #2 and #3 above. When triggered, the output of the monostable timer drives the oscillator's RESET high causing it to pulse for the duration N. However before the circuit has been triggered and after it is finished, the output from the oscillator is driven to GND by the second 555. This is undesired, since in my application I am pulsing an active-low device. I would like to understand if there is some way to pull the output of this circuit to either Vcc or have it floating, when not pulsing.


texts: How to combine or simplify multiple 5-12V level shifters

texts:
I've created the following model for a school project. This is the first time I'm attempting to read sensors or write alarms etc. using a microcontroller.

How I can improve it? To me it seems likely that there's a way to combine these voltage converters.

As I was thinking, I could perhaps use one pin to control/read the sensor and another pin to 'multiplex' the other pin to the correct sensor after it's voltage has been shifted from 5V to 12V.

Would you recommend this approach? Or is there a much better or more common alternative?

Note:
All sensors have to be read, whereas the alarm has to be set. The temperature sensor is an analog sensor, all other sensors are digital.


texts: Experiment - measuring current across two resistors

texts:
My goal is to measure current at different points in the circuit. I took breadboard, D battery, two resistors and multimeter. Here is how my circuit looks schematically:

Using multimeter I checked:
D battery voltage is 1.87 volt.
Each resistor is at 100 ohm

Now when I measure current across the first and the second resistor individually I get around 20mA. It probably does not match Ohm's law due to error of measurement. Now when I measure current across both resistors simultaneously I get 1. I guess it means overload. I am expecting to read the same 20mA. What am I doing wrong?


texts: Why is my oscillator circuit not working?

texts:
In the book I am following the following circuit is given:

simulate this circuit – Schematic created using CircuitLab

The book states that as soon as we apply power to the circuit, the LED should start flashing.

However, this doesn't happen in my circuit. As soon as I apply power to my circuit, the LED flashes once and stays off after that.

What might be the reason my circuit does not work? I am giving my circuit below:

Since I don't have exact resistor values, I have made R2 out of 10K Ohm and 4700 Ohm resistors. And I have made R3 out of two 10K Ohm and one 6800 Ohm resistors.

I don't know which manufacturer's 2N6027 (PUT) I am using but AFAIK their pinouts are always the same.

I am using an AC to DC adapter at 6V as my power supply.

What I have tried up to now:

Replace R1 with 100K Ohm. Didn't work. Same behavior as before.
Try transistor's (a user) circuit. Didn't work. This time LED didn't flash even once. The following is transistor's circuit:

Increase the cap.
Increase the cap and decrease R3.

Measurements:

Current at anode starts at 5uA as soon as I power the circuit, and drops to 0uA about a course of 5 seconds and stays at 0 afterwards.
Current at cathode becomes 1uA momentarily as soon as I apply power and then drops to 0 and stays that way.


texts: Voltage boosting device for electrostatic experiment

texts:
I want to get 2kV to 6kV (adjustable) for performing electrostatic experiments with parallel plates.
What device can produce such high voltages from the 230V mains?

I watched a video on YouTube experimenting with electrostatics. They had used a device which looks similar to a bench power supply to step up the voltage to 6kV.

It looked like this:


texts: PCB design of the copper area of a (linear) power supply

texts:
I design an amp with 2 linear power supplies (1 HV main PSU+1 LV preamp PSU) and other devices. My concept is to put the star point onto the board of the main PSU:

I have some concerns / questions about my concept:

I have a big ground area on the front copper (red area). The area
between the big reservoir caps has high ripple currents. Does this
affect my star point negatively or is it far enough? Is it better to
just draw a thick track from reservoir ground to the star point
(without big ground area) ?
Is it a good idea to put the star point onto the board of the main
PSU? Or is it better to connect everything including the main PSU
somewhere externally using thick wires? Will this have better
immunity from ripple currents?
I used relatively big areas as power lines and high current lines (yellow areas, back
copper) instead of thick tracks because of high current. Good idea?
Will it cause any issues with capacitance? Should I use more
decent/thinner power lines?


texts: Momentary button for voltage boost circuit design

texts:
I am just starting to dabble in electrical engineering and circuit design, so forgive my ignorant questions. I am trying to get started building a very simple experiment with my son and I'm not sure where to even begin, so any guidance at all is very much appreciated.
First, we have a 12VDC 2.8A 3500rpm 21W motor with a 12VDC power supply.
(Edit: I'm not stuck to this particular motor or voltage in any way, if we can achieve the same effect with something smaller that is fine as well.) What I'd like to do is create a momentary increase in the supply voltage to increase the speed of the motor for a second or two. Almost like a turbo booster button.
My first thought was a secondary power supply in series with the primary 12VDC connected with a momentary SPDT switch. Seems simple enough

But I'd really like to charge up the "turbo booster" button so he can learn about (small-ish) capacitors. But I'm at a loss on how to supply voltage to the capacitor from a secondary power source and then discharge it in the series to quickly burst the speed of the motor until the capacitor is discharged and the SPDT button is released to recharge the capacitor. I'm sure there is a very simple answer to this, but I can't seem to find a good place to start.
Thanks in advance!


texts:
I was watching a tutorial about this MCU (TM4C123 dev board), but I don't understand where they got the memory location address from. All they are doing is switching the built in red LED on the board on and off.

They are setting bit 1 in the GPIODATA register (see attached image of the datasheet for this register) with the address 0x400253FCU and writing a hex value of 0x20U to it. They then clear the bit by writing 0x0U to the same address to switch the LED off (there are time delays in between off course).

My question is, that I don't understand where the offset of '3FC' comes from? I am used to just writing down the offset given in the datasheet. In this case I thought it would have been 0x40025000U.

I think I am misunderstanding something due to the fact that this is a 32-bit MCU.

Thanks for all help everyone.


texts: Resistors between Arduino pin and transistor

texts:
I'm trying to activate a relay using an Arduino Uno. Most schematics I have seen in the web include two resistors between the Arduino pin and the 2N3904 transistor.

What is the reason for that?


texts: help building 6S2P balanced Li-Ion battery pack

texts:
I'm trying to build a 6S2P balanced Li-Ion battery pack for a quadcopter using LG 18650 HG2 cells with pre-soldered nickel strips (1st image) so that I won't solder directly on the cell's terminals.

so I have some questions:
1 ) I'll put the cells inside the 2 disassembleable arms so how do you advice to keep them in position (2nd image) and isolate e.g. the gray circled terminals (3rd image)?

2 ) is this diagram correct or are there better solutions?

3 ) I'll draw a maximum of 30A continuously, are 16AWG wires enough?


texts: Why led is on when there is no input at terminal 1 &2 for 7432 IC?

texts:
I have two questions under same heading:
First why the led connected to terminal 3 and ground is always on when terminal 14 is connected to 5V and 7 to ground when there is no any input at 1 and 2?

Second As we give inputs to 1 and 2 and have output at 3 why we need to connect 14 to power supply and 7 to ground?

Thanks!


texts: When driving a unipolar stepper as a bipolar with a chopper driver, should I decrease the current to prevent overheating?

texts:
I am driving a few stepper motors using a A4988 chip, and my motors are unipolar. The driver I chose is bipolar, so, obviously, I've decided to drive it as a bipolar stepper by leaving out two of the leads. (Haven't decided which to do; one way will increase torque and another will increase speed.) Do I need decrease the current that the chopper driver can supply to prevent damaging my motor?

EDIT: I'm concerned that the current from energising double the amount of coil at one time that if I drive it at 1.5 A, then it will overheat because of resistance. Someone has said that since there is more resistance then you can technically run it on a lower current because of ohms law with the same voltage... blah blah blah. But since I have a chopper drive... please inform me on how much current is safe. Could I add an external heatsink somewhere to be safe?


texts: As I understand, class-C amplifier can only generate signal of constant frequency and amplitude. So the question is, how can it be useful and what are its applications?


texts: How to select the most appropriate (serial) bus for controller?

texts:
In the context of a robotic project where different 'payloads' and/or robotics arms (end-deflector) should be mated mechanically with power, data and control connections support, I would like to identify the best suited (serial) bus.

I have a hard time putting together the requirements, but the main 5 important ones could be summarized as following:

Minimal wiring: 2-3 pins (or less)
Multi-points/clients, if possible without host/client/server/master aspects
The-wiring-is-the-bus (=no need for repeater/switch/hub)
Hot-pluggable/swappable: adding/removing clients, changing the topology
Support for different topology: straight, meshed, star, fake-loop,...

Speed is not really a constraint.

Currently CAN bus was used in our bread-boarding, in order to inter-connect a few RasPi/Zero with PICANDUO daughter boards, covering almost all 5 requirements except of course #4, as it is not meant to be hot-pluggable and thus gives issues for #5 (especially moving/adapting the 120 ohms termination resistors). We then use a flying master for changing the master of the bus.

Ethernet would be almost covering all 5 (except #1 & #2), but is completely overkill...so is SpaceWire. SpaceFiber could be an option.

I am also considering RS-485, LVDS, I2C, 1-Wire,... But these seems to get trouble with #4 (end resistor) too.

USB would be great (only 2 data wires, powered separately), but it requires a single (stable/single) Host/master (or does it?).

Am I overlooking a specific bus here?
What would you think of other potential candidate(s) here?

Thank you for your hints!


texts: Reliability problems with an array of 91 high-power LEDs

texts:
I have designed and printed a 4-layer PCB that accommodates 91 infrared LEDs in a 7x13 rectangular layout. This will be used as a backlight for a machine vision project. I am having a problem where individual LEDs are burning out or perhaps becoming disconnected from the circuit in some way. I suspect the heat dissipation may be the cause of the problem.

Image

PCB Layout

Each row of 7 LEDs (green LED text) is wired in series. The 12V supply (VCC powerplane) connects to the first LED. The next 6 are wired in series. Finally a current-limiting resistor (green R text) connects the last LED to the ground plane.

Specifications:

VCC plane: 12V, 2A supply
LED: TSHG6200. 100mA maximum rated
current.
Current limiting resistor: 20 ohms
Solder: Thermoflow
Sn60/PB40
Total estimated power dissipation: 12V * 0.1A per row *
13 rows = 15.6W.
Size of array: 13 rows of 7 LEDs, approximately 7cm
x 6cm

Measurements

With a 12V power supply, there is about 1.45V over each LED, and about 2.0V over the current limiting resistor, meaning a current of 100mA. Because this is right at the maximum allowable current, I put a big high-power potentiometer between the power supply and the VCC plane, and used this to regulate the input voltage to be slightly lower (11.5V or so). This gets the current safely below the maximum allowable amount.

I am also using a Darlington pair to control the backlight with an Arduino. The backlight is on almost all the time, and occasionally is pulsed off for about 30ms. I don't think this is relevant to the problem but can provide more details if necessary.

Problem

After about 10-30 minutes of use, one or more of the rows of LEDs will go out. If I measure the voltage across each LED in the broken row, most LEDs are at about 0.8V and one has about 8.0V across it. No current is flowing. Sometimes resoldering the pins or tapping the LED fixes this. Sometimes it has to be replaced. In any case I only get another 10-30 minutes of use before another one goes out.

Another observation is that the whole back side of the board is kind of sticky. You can see this in the picture above. I wonder if it is getting too hot and the solder is becoming compromised (perhaps exuding flux??).

Question

What should I try to improve the reliability? I've already tried running it at a lower voltage to get the current safely below the rated maximum. I wonder if I need to use a different kind of solder? Or some kind of heat sink? The LEDs get hot to the touch but not unbearably so.

Edit, after trying suggestions

Thanks everyone for the tips! I did something quite simple -- pointed a computer fan to blow air across the array -- and it worked fantastically! I guess this is really obvious to many of you but I was surprised at how enormous the difference was.

Without fan:

25mA per row -> 39C
33mA per row -> 41C
40mA per row -> 48C
55mA per row -> 52C

So we get into the "danger zone" of temperature well before reaching the maximum current per LED.

With fan:

35mA per row -> 26C
60mA per row -> 30C
90mA per row -> 34C

I ran it at 90mA per row and 34C for over an hour with no problems. Great!


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