texts:
I have avrdude 6.3 installed from Homebrew on Big Sur on M1 chip.
When trying to run:
sudo avrdude -c atmelice_isp -p m1284p -t -v

I get:
         Using Port                    : usb
         Using Programmer              : atmelice_isp
avrdude: usbdev_open(): Found Atmel-ICE CMSIS-DAP, serno: Jxxxxxxxxxx
avrdude: usbdev_open(): error claiming interface 0: Permission denied
avrdude: usbdev_open(): no usable interface found
avrdude: jtag3_open_common(): Did not find any device matching VID 0x03eb and PID list: 0x2141

avrdude done.  Thank you.

I could not find anything related to this issue nor do I know how to address it. Are there any tips on how to address this? Is this is a known issue (that I somehow missed in my research)?


texts: How do I effectively trip a digital Hall effect sensor with low current. Magnetic field amplification?

texts:
This is part of a more complex project for school but here is what you need to know to help me.

I have a DC voltage from 0-5 volts
I must include a resistive load.
The Hall effect sensor trips a digital 0 in the presence 4.9mT of magnetic field.
I want to be able to sense currents on the uA maybe nA scale.
Anything I add to my circuit can't change the DC steady-state current.

What do I add to my resistor circuit to "amplify" the magnetic field due to current?
Should I try to make a small DC transformer to get a larger magnetic field?
I am thinking of just adding an inductor in series with the resistor and pointing it at the Hall effect sensor.
EDIT:
This is the hall effect sensor
https://www.ti.com/general/docs/suppproductinfo.tsp?distId=26&gotoUrl=http://www.ti.com/lit/ds/symlink/drv5021.pdf
It's a drv5021A1.
Sorry my post was confusing I meant to say I must Include a resistave load. But I know I will probably be adding an inductive load as well.


texts:
Need a good 1 wire temperature sensor, there is a lot of information about the DS18B20,
but I see nothing about it's quality or expected lifetime.

I was wondering which is the expected lifetime of a DS18B20?

I see them packed in probe fashion,  need them like this. It seems that the company does not makes the chip pocket or probes themselves. Also there are bad reviews out there.

Are these thermometers serious to use at commercial level? If not, What other alternatives are out there for practical (maybe harsh?) use?

Would love to hear real world experiences...


texts: Simulate throttle position with an Arduino

texts:
I am doing a project for learning purposes which consists of controlling the output of the throttle position sensor of my car. In other words, I would like to use the Arduino to simulate the pushing of the accelerator pedal.
My throttle position sensor is called "CTS 4089." it is for a Renault CLIO/Twingo. It has 6 pins, from which, from a quick look with a multimeter, seems that the first and fourth pins are positive 5V.

How can I do this with Arduino?
What do you guys suggest?


texts:
I have what should be a schematic file from a vendor, its suffix is .sch.  I tried opening it with Eagle CAD but it wouldn't open.  I then looked at the file with a text editor and there seem to be some references to Orcad.

Does anyone know if .sch files are Orcad files, and if so where to get a free viewer program from?


texts: Applying KVL on RC circuit to get the natural reponse v_c(t>0)

texts:
I want to find the equation for the discharging of the capacitor \$C\$. My initial thought was to use KVL in the closed loop that is the circuit with the current \$i\$ going anti-clockwise (since the capacitor has \$+\$ on top the current will go anti-clockwise). This gives the equation

\$-v_C + v_R = 0 \Leftrightarrow \$

\$-v_C + Ri = 0 \Leftrightarrow \$

\$RC \frac{dv_c}{dt} = v_C \Leftrightarrow \$

\$\frac{dv_C}{dt} = \frac{1}{RC}v_c\$

Solving this gives: \$v_c(t) = v_c(0) e^{\frac{t}{RC}}\$

However, this is exponential growth and will go to infinity as t goes to infinity. What I want to get is \$v_c(t) = v_c(0) e^{-\frac{t}{RC}}\$ which tends to \$0\$.

My school book use the upper branch as a node and applies KCL to it with currents going downwards for both the resistor and the capacitor. This will give the correct answer.

What I want to know is what have I done wrong in my method with KVL that gives the wrong answer?


texts: Powering RC Servos using Switching Power Supply

texts: I have 3 RC HV Servos (working voltage 6-8.4V) (link). I purchased a 75 Watt Switching Power Supply (link). The servos draw about 3amps at full load.Is a 75Watt supply sufficient or do I need more just to be safe? Also, is it safe to connect the servos directly to this supply or do I need to add a current limiting resistor between them?


texts:
I have a voltage divisor to measure the voltage of my battery which serves as a battery level detector and it is connected to a GPIO pin in a microcontroller which does not have an ADC. Is it possible to obtain the analog value? And if not is there another way to obtain the value without an ADC?

I have seen a way that will compare the voltage of the Vref of my microcontroller. Is it possible this way?

For the MCU, im using a STM32WB55CGU6 and the pin used is the PB6 (pin 46)


texts: analog circuit design resource recommendations

texts:
What are some excellent resources related to advanced analog circuit design? This includes RF, sonar, audio, low-frequency, high power, low power, noise, amplifiers, etc.. To get the most obvious contender out of the way, I currently refer to...
The Art of Electronics 2nd ed.
by Paul Horowitz and Winfield Hill, 1989

It isn't exactly a cookbook, but it also doesn't go into detail about each design, so it requires an electronics background to use. As such, it is excellent.
However, I know there are more specialized and advanced resources available. What do you use?


texts:
Can someone please explain to me why the output of this level-shifting circuit starts charging from around 2.8V to 5V, and NOT from 3.3V to 5V.

At the time where the output is at 5V there is a 3.3V potential at the source and gate terminal.

So i thought that the drain-source capacitance and the gate-drain capacitance would ramp up from 3.3V to 5V.

below is the circuit diagram and oscilloscope pictures. I get the exact same results when simulating the circuit, so i am definitely missing something.

UPDATE:

After studying my simulation a bit more:

This is what it looks like when i zoom. The voltage is initially 3.3V. Could this be due to reverse recovery??? so that the body diode conducts in the reverse condition for a short period of time. Could that be why the source voltage goes to 2.7V because of a diode drop?


texts: how many cell phone can I charge at the same time on the same circuit?

texts: I work at a courier company and we use a lot of cell phones, most are recharged over night. The current practice is to utilize cheap power bars which can handle 6 chargers/phones. Thinking of setting up to store and charge from 18-24 units using 3-4 power bars. Basing the current draw of 100ma per charger this would result in between 2 and 3 amps for the total circuit. Am I on the right track here? Is it better to turn off the phones while charging? My major concern is safety/fire risk and I do not want to overload the circuit. I will have to check what else is on the circuit that I plan to use. Do not want to trip any breakers and affect other equipment.


texts:
Is there a technical word for the circuit that a relay turns on?  In this case the circuit on the right side.

simulate this circuit – Schematic created using CircuitLab


texts: Help building acceleration detection device/circuit for my bike

texts:
I want to build a device using an accelerometer. Press a button after a bike ride and have a light turn on if during the journey I managed to attain a certain acceleration.

Thinking of using some kind of flip flop and switch (using a circuit to hold one byte?), but need help with details, how to set up the circuit. I would need to be able to reset it too. The cheaper I can get my results the better.

I have started learning how to use Arduino board, can make simple projects.


texts: I am designing with nrf52832 and experiencing some BLE connection issues at 0C. The system gets disconnected every few seconds with 32k crystal, but no issue with internal RC oscillator, so the issue should be related to the crystal. I confirmed the crystal meets the datasheet specs and changing the caps help. What's the best way or tool to validate the capacitor value? Right now I just changed the cap and put the system at different temp to check the connections for 30+ minutes (including soak time). Any other less time-consuming methods, e.g. toggling GPIO and measuring the frequency drift?


texts: Are optocouplers enough of a protection to sensitive electronics

texts:
There are certain lines in my car which I want to detect when hot. My initial thought was to hook a voltage divider to drop from 12v (or ~14 rather) to 3.3 and feed it to my pi but I soon realized that I'm probably going to have a bad time due to fluctuations and stuff.

Would it be enough of a safety precaution if instead I use an optocoupler such as 4n25 and feed the IRLED from the line I want to monitor via a 1.3k resistor to get about 10mA?

Additionally would changes in the voltage of the electric system (and therefore the line I'm feeding the LED from) cause changes in the voltage of the transistor side of the 4n25? Or in other words does the brightness of the IRLED(?) affect the state of the transistor or is it stable once it reaches a certain threshold?


texts: NPN transistor: collector branch question

texts:
The circuit below acts as a simple nightlight: when it's dark out, the LED turns on, and when it's light out, the LED turns off.

What I don't understand is why the LED wouldn't always be lit. Why would the NPN transistor limit current from flowing through the top branch at all times.


texts: please do not know if there is a functionality in CADENCE in the graphs show differences in the times between them (make an average of two values). Regarding the delay of two waves [Automatically in the graph or table]. Example is in the image.


texts: Eagle - export image of holes for component leads

texts:
I'm wondering if there is a generic method used by all cnc machines to create a png of the holes for component leads. As the Modella MDX-40 drills the holes first then mills the traces. All done at the same depth. I need a png of the holes which I then use on a different setting to drill all the way through. I'm using Eagle to create my layout.

I apologise if it's different for every cnc machine.


texts:
One of my problems asks me to find the voltage at time greater than zero. The first part of the question asked me to find current. I was able to solve that part and found it using the general solution for step response of RC: i(l):5+15e^(-1000t) Amps t>0.

the back of the book tells me thing: note the 10 is the resistor

vo = 10(io) + Ldio/dt
= 10(5 + 15e−1000t) + 0.04(−1000)(15e−1000t)
= 50 + 150e−1000t − 600e−1000t
vo = 50 − 450e−1000t V, t  0+

Can anyone explain why? I understand that V(l)=L di/dt and ohms law but why to I do both to find voltage at time greater than zero.

thank you.


texts:
I realise this verilog code isn't ideal, and later on I might ask for general review somewhere but at this time I'm not looking for general review except so far as it affects the issue I have (unless they whole thing is fundementally broken of course, then I want to know!). I realise the timing probably isn't quite right, and hard coded numbers etc are likely  bad, it's just a first attempt to learn, and my problem is understanding the warning at the moment.

I'm trying to make a VGA output on a papilio pro. It's somewhat working if I just output the vertical and horizontal sync but when I try to output the rgb signals I get this warning :-

  WARNING:ConstraintSystem:119 - Constraint <NET "vga_r"    LOC="P78"
    |>    [main.ucf(6)]: This constraint cannot be distributed from the
  design objects    matching 'NET "vga_r"' because those design objects
  do not contain or drive    any instances of the correct type.

  WARNING:ConstraintSystem - A target design object for the Locate
  constraint    '<NET "vga_r"    LOC="P78"   |> [main.ucf(6)]' could not
  be found and so the    Locate constraint will be removed.

module main(input clk_32, output vga_hs, output vga_vs, output vga_r, output vga_g, output vga_b);

    wire clk_50;

    // Use a clock generator IP module to make a 50MHZ clock for the VGA
   clkgen clock_gen(clk_32, clk_50);

   // Current scan line number
   reg[0:9] row_count;

   // Current pixel position in scan line
    reg[0:10] pixel_count;

   always @(posedge clk_50)
    begin
        if (pixel_count == 1599)
         begin
             pixel_count <= 0;
           if (row_count == 524)
              begin
                  row_count <= 0;
              end
              else
              begin
                  row_count <= row_count + 1'b1;
             end
         end
         else
         begin
             pixel_count <= pixel_count + 1;
         end
    end

    // Set "on" only during the visible part of the screen
    wire on;
    assign on = (pixel_count > 112 && pixel_count < 752) && (row_count > 12 && row_count < 492);

    // Assert the hsync and vsync pins during the proper parts of the video frame
    assign vga_hs = ~(pixel_count < 96);
    assign vga_vs = ~(row_count < 2);

    // Just turn on the R,G,B outputs during the main area of the screen for now.
    assign vga_g = on;
    assign vga_b = on;
    assign vga_r = on;

endmodule

and my UCF file contains this which I think is correct...

NET "clk_32"    LOC="P94"   | IOSTANDARD=LVTTL | PERIOD=31.25ns;
NET "vga_vs"   LOC="P99"    | IOSTANDARD=LVTTL;
NET "vga_hs"   LOC="P97"    | IOSTANDARD=LVTTL;
NET "vga_b"    LOC="P92"    | IOSTANDARD=LVTTL;
NET "vga_g"    LOC="P80"    | IOSTANDARD=LVTTL;
NET "vga_r"    LOC="P78"    | IOSTANDARD=LVTTL;

clkgen is a clock generator generated by the tools and appears to be working correctly.

I don't undersdtand what the warning is telling me, it appears to be preventing the synthesis from working though. It all looks right to me but I'm clearly missing something, can anyone see what I'm doing wrong? (And be gentle I'm new to verilog!)


texts: Can an item be damaged if placed on the outside of an anti-static bag

texts:
Some people warn against removing an item (eg. a graphics card) from an anti-static bag and placing it on top of the bag. Others say the bag should be turned inside out. Others say there's no problem.

Is there a definitive answer? (preferably with scientific proof)


texts: Is there a design flaw in this voltage regulator application?

texts:
I am a veterinarian and I need some help.  I purchased two very expensive lift/weigh table/scales. After about 5 years of service one of them failed.  I determined that the main PC board had failed.  If you look at the cover of the PC board the cover is smoked over the voltage regulator.  I removed the operating PC board from my other identical scale and noted a similar degree of smoke (see attached picture).  The voltage regulator is an L7808 (8 volt) regulator.  The fact that the other scale had a similar degree of charring/smoke made me concerned about a design flaw.  When I did the math it seemed to point out that the application was exceeding the thermal limits of the regulator.  I measured the input voltage at 19.5 volts (on both of my tables and two my brother has as well) from the AC/DC transformer installed in the base of the table.  I think they should have placed the regulator on a heat sink or they should have a lower input voltage. Attached are pictures of the board and the housing that it smoked.  Here is a reply from the company as well. There is no way this unit has the input voltage they claim. My question is:  would the input voltage of 19.5 exceed the design specifications of this voltage regulator in this application (also not has no fan on it and is covered by a tight metal cover).  They want $600 for a new board (which I don't mind paying); however I don't want a repeat performance at that price and my other scale tends to indicate I will!

Company response:

  Dr. Wittman,

  I am sorry you did not receive a call on Monday, I was out of the office unexpectedly on Tuesday the 13th. This is the measurements and readings from a Canis Major coming off our line today,

  14.6VDC Measured input with load
  190mA Current Measured with load
  Pd=(14.6V-8V).190+14.6.008A*=1.38W
  Junction Temp=Rthja*Pd+Ta=65°C/W*1.25W+25°C=106°C
  The temperature of the voltage regulator is within the required specification on the datasheet. The part however will get hot, like most any linear regulators.


texts: What microcontroller has 20 or more ADC pins?

texts:
I'm looking for a microcontroller with at least 20 ADC pins.  Most things I'm used to using like an Atmel or Arduino have only a handful of ADC.  I need to decode 20 analog wave forms being used to drive a segmented LCD screen.  Any suggestions of where to find such an MCU or an alternative approach to solve this problem?

Edit: The LCD screen I'm looking at doesn't have a part number and it is custom to the product it is in but I believe it is using a scheme like the one described as "multiplexed" in this blog http://www.circuitvalley.com/2012/02/pic16f917pic16f1907-7segmentlcddriverex.html with 16 SEG pins and 4 COM pins


texts: I have been working on a development board for the Orange Pi Zero platform. I want to add a button which allows to restart the board. Is it possible to implement such functionality?


texts: Getting the best range with XBee-Pro 900 XSC S3B

texts:
I have a pair of 900 XSC S3B xbee pros and a couple 2dBi duck antennas. I just did a simple outdoor range testing and only got about 2,000 feet. I was outdoors without any buildings in the way, but there were a few small things between me and the other radio. That's the range expected for indoors or an urban environment....however, I'm going to need something better/stronger/further.

The basic idea for what I'm trying to do is build something to communicate location between two bicycles at Burning Man. There will be an arrow mounted on each bike (mine and my girlfriend's), and at any point one of us can press a button and the arrow will point in the direction of the other. So each bike will need to be constantly transmitting it's location to the other.

Burning man is a temporary camp-city in the dessert that is 5 miles wide with ~60k people. There are no cement structures but many camps, RVs and wood structures. Most camp structures are under 15 feet tall.

How can I make this project work? Are there a better RF transceivers and/or antennas that I should be using? Would upgrading the 2.1dBi dipole antenna to a 8 dBi whip antenna help, even in non-line of site operation? I'm thinking of putting  a repeater at the top of a 20 foot pole, however, it will still wont always be perfectly line of sight with each devices at all times.


texts: PID controller algorithm for sr90 digital controller

texts:
I am trying to implement PI control algorithm in c#. I found some help in internet and i understand the formula how to use. I have measured value(PV)= 20 °C  and set point (SP)= 80°C; I would like to update every 2 sec in time. once the measured value reach to setpoint the controller has to switch off like that.

I found this code link to pid algorithm

but what i need is how to calculate gain factors Kp and Ki gains as well as what about dt. I am neglecting Derivative. So please can anyone explain me how to calculate those gain factors. I am using shimaden SR90 digital controller(i bought this). I found some factors in the manual but i am not sure can i use those gain factors.

  Edited for doubts.

I have tried your code like this, i am not sure this is the correct way or not.

int temperature;
//int setpoint; // i have commented these because we never used.
//int status = 0;
int pulses = 0;
//int integral = 4;
//int derivative = 5;
int upperTemp = 1000; //100.0C
int upperLimit = 100; //pulses per time frame // i can take 100 pulses per sec.

 runtime //make a timer that runs and updates temperature value...lets say every second
{
  read temperature; //every second
  temperature *= 10; //multiply by 10 for decimal place, but still keeping in integer
  pulses = map(temperature, upperTemp, 0, 0, upperLimit);

  //take this value of pulses to update the timer interval
   I didn't understand the above line if i am right then here i need to call the
   timer like
   if(pulses> somevalue)
     call timer
   else
     no call
  }

//borrowed from arduino
long map(long x, long in_min, long in_max, long out_min, long out_max)
{
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

I have some question here
1) This method seems to be different than previous because we never used gains or error in this method?
2) I understand that "upperTemp" is the setpoint value.

I have tried with simple example like this

 int temperature = 20;
 int pulses = 0;
 int upperTemp = 800; //80.0C
 int upperLimit = 100; //pulses per time frame // i can take 100 pulses per sec.

 read temperature; //every second which is 20 in this case
 temperature *= 10; //multiply by 10 for decimal place, 20*10 =200;
  pulses = map(temperature, upperTemp, 0, 0, upperLimit);// map(200,800,0,0,100)

 //then map function will return pulses = 75;

//then here i don't understand that much but i am thinking like that

if(pulses> 75)
  switch on;
else
   switch off;

I am not sure that i am doing right! can you suggest me some more here.


texts: How to generate tones of different amplitude with Arduino

texts:
For a new project with Arduino I need to generate an alarm tone that needs to increase in amplitude over time if the user doesn't take action. The output would be via a small speaker.

So when the alarm condition triggers I would generate a low volume beep in the audible range, give the user some time to react, then increase the volume, wait, increase again until the user reacts. This way I don't generate a loud alarm tone from the start, which can be disturbing in a quiet environment.

Generating pulses and using a transistor or IC amplifier to drive the spaker is no trouble.

--> The issue is: how to modulate the amplitude of the speaker sound?

My limitation is that while sounding the alarm, the Arduino still needs to to other stuff, so I can't stall it in a complicated routine to generate tones for example by doing some fancy PWM that then gets filtered to deliver a signal with different amplitudes.

I could use one pin to generate the base frequency signal, and have 3 pins available to steer some external circuit to modify the amplitude, like this:

Do you guys have some ideas to share?

Tks!

ADDENDUM:
This is the solution I had tried out already, but the volume levels are not repeatable from one unit to the next, so I would like to avoid adding a trimmer pot.
D13 generates a square wave with the audio tone. The other outputs pipe this tone through the resistor ladder via the AND gates.


texts:
I have been working on an IC from Fairchild semiconductor named FL5150, whose electrical working I have tested by controlling the brightness of a lamp. Until now I have been using the circuit given in the datasheet with a manual potentiometer.

But one thing which I am not able to understand is the circuit in this portion.
.

When the current passes through the MOSFET, the mid-point of both the MOSFETS is in direct line of AC supply. But that part is also connected to the Ground of the IC. How is this thing working? Is the voltage on the mid-point of both the MOSFETs at a constant voltage?


texts: How would I go about detecting at motor controller level, that my PWM signal coming from my microcontroller is at 50% duty cycle.  I would like to design a dead band into my motor controller so that I only have a single PWM signal coming from my uC instead of PWM, CCW, CW signals to free up ports.


texts: Got audio mixer circuit with lot of noise. Using two different circuits with same output and noise

texts:
I'm trying to do a simple audio mixer.

For that I tried 2 different circuits:

Circuit 1:

which uses LM3900 chip:

http://www.theorycircuit.com/audio-mixer-circuit/

Circuit 2:

which uses PN2222A transistor:

https://circuitdigest.com/electronic-circuits/single-transistor-audio-mixer-circuit

This is my implementation of both circuits:

where I connected as inputs my smartphone and laptop, and the output is my headphones.

My problem is: Even though I can listen both inputs mixed, there is lot of noise. So, I'm wondering if there is another circuit I need to connect at some point, maybe to amplify something. Both circuits has the same output with same mixed audio and same noise, etc. I would say I cannot distinguish between the output of both circuits.

Any idea on how to get a clear output with no noise?

Thanks!


texts:
A static distribution of current (including volumetric and surface) generates a corresponding magnetic field depending only on the cylindrical coordinate \$r \$ and points in the z-direction.

Find the (volume AND possible surface) current distribution

I know that volume current density is related to the magnetic field via \$\hat n \times (H_2-H_1) = J_s\$, but where do I begin?


texts:
Part searching in microcontrollers, it looks like most small ones have at most one DAC. What is the just way or ways to output multiple slow signals from a microcontroller with at most a single DAC?

For instance, what if I'm trying to output 4 signals with up to 100Hz bandwidth and 8 bits of resolution?

Here are the solutions I've come up with:

Use an analog switch with an amplifier doing track and hold for each output. Unfortunately, this requires the most board space probably, and the charge injection from the switch and bias current of the amplifiers require some moderately large capacitors (at least nF).
Use a dedicated sample and hold amplifier for each output. Unfortunately, the cheapest ones are in the 70 cent range at quantity, and I'd need at least two.
Just buy a DAC with multiple outputs. Unfortunately, the cheapest 2-output DAC seems to be in the 60-70 cent range at quantity, the same as the microcontroller.


texts: Why would a device require at least 10m of wire between its outlet and the service panel?

texts:
I found this warning on a little slip of paper, in with an Insignia surge protector:

  DO NOT install this device if there is not at least 30 feet(10 meters) or more of wire between the electrical outlet and the service panel.

What could this be about? What are the odds that the device is actually designed to make use of the properties of that 11m+ run of cable?

Also, how the heck is it ok to have a restriction like this? Our service box is optimally located in the center of a small home! Most outlets and appliances are within a 10m run of wire from the box.


texts: How to securely lock 100% a microcontroller like ESP32 or ATtiny85 or any other ATtiny?

texts:
I have been doing research on how to securely lock and prevent 100% from someone seeing my code.
ESP32 can be "hacked" see here.
ATtiny has fuse bits that can be set to protect the code but again someone who knows how to or pay someone can get them unlocked.
This is not a question about if I really want it to be locked or not and if my code is so important and if I am Chuck Norris in programming.
Is there any microcontroller ESP32, ATtin85, other ATtiny family, or any other microcontroller which would provide 100% or nearly 100% protection?


texts: How to design new flip flop using JK flip flop

texts:
I have an excitation table that called MN flip flop like below.

Q Q' M N
0 0  0 X
0 1  1 X
1 0  X 0
1 1  X 1

I try to design a counter that count 0-7-2-3 in Proteus. In my estimation, this excitation table is like JK flip flop's excitation table and if I use not gate for K values, I find N values, is that possible like that converting? If not, how can I design flip flops like above that has excitation table for Proteus design. Any offers?
Thanks.


texts: Can I put graetz circuits' outputs in series and parallel?

texts:
I will have multiple coils that generate alternate current. Those coils are placed around a wheel which has some magnets on it. My current plan is to make it look like this:

I was considering rectifying output of each and then putting the rectified voltage in both series and parallel. For example of four coils, two and two would make series to increase voltage and those pairs would go in parallel for greater maximum current. That would look like this:

simulate this circuit – Schematic created using CircuitLab

I would probably add some capacitors to balance the voltage. But is this even possible?


texts: Power strips show fault in some outlets but not others

texts:
I'm not sure if this is on topic or not, but I thought I would ask.

I have a few power strips (surge protectors) in my house that I use for computers, TV, etc.

Some of these have a "fault" or "surge" light on them.  Some of them have "protected" light.

These are three prong power strips.

My question is, why do these show surge or fault on some outlets and on others, they do not.  I'm assuming it's some polarity issue with neutral and hot?  I know almost nothing about AC current.

Also, should I be concerned about this or should I have an electrician inspect these outlets?

Thanks.


texts: How to efficiently boost a low voltage high current input to a high voltage low current output

texts:
I have a 3.7V 6600 mAh lithium-ion battery that I'd like to use to power some small 6V motors that only require 500 mA. However, I need the battery supply to last as long as possible (which is why I'm using a large mAh rated battery).

How would I convert the lithium's output to 6V @ 500mA as efficiently as possible using an off-the-shelf component?

I see a ton of cheap Chinese buck-boost dc-to-dc converters with switching regulators that claim to do this, but are they the most efficient method? I'm worried these are designed to step up both the voltage and current, not invert them as I need, and so will still be wasting a lot of watts.


texts: Boosting the Analogue Response of a Sensor

texts:
I have a A1308KUATN-9-T Hall Effect sensor with the following sensitivity (from the data sheet):

As you can see, the sensitivity comes to about 9mV per Gauss on average.

My calculations (see below if you think this sounds wrong) come out to a flux density of 1.36 Gauss when I'm 3 inches above the magnet.

So that means I can expect a reading of 12.6 mV on my sensor's output... My goal here is to try to boost this to something closer to say 3V or so. Using an op-amp is the direction I'm assuming I should be taking, but if there's a better way I'm open to that.

Additionally, I'm really worried about noise affecting this. In other applications I'd say noise on a signal of +/- 10mV is fine but here it'd be terrible. If I put a decoupling capacitor on the 5v rail going to the hall effect, would that help clean up my noise? Should I do something between my sensor's output and op-amp's input?

So finally, to summarise: I'm expecting a ~12mV analogue response from a sensor that general outputs 0-5V. So I'd like to boost it the best I can and filter out any noise that could give a false reading (since the expected signal is so low to begin with).

For those interested,

Explanation for Flux density calculation:

The cylinder magnet I'm trying to detect will be approximately 3 inches below my sensor and given a diameter of 12mm and a height of 2.6mm with the assumption the residual magnetism of my magnet will be ~1.3 T.


texts:
I'm looking into purchasing a winch that is powered by 12V DC.
It's a 1 horse power winch, so I assume it requires just over 700 Watt to function at max load. Right?

I want to use it at home, so I somehow need to convert 110V AC to 12V DC.
When I look for 110V AC to 12DC coverter online nothing comes even close to 700 Watt.

Am I on the right track or what I'm trying to do doesn't make sense? Why are there no converters for that?


texts: Honeywell I2C RH Sensor SDA line experiencing fluctuation between Vdd and Vdd/2

texts:
I had a problem when implementing I2C communication between NXP Kinetis K50 micro-controller and Honeywell Humidlcon I2C RH sensor. The RH sensor doesn't acknowledge when receiving the default address 0x27. After testing SCL and SDA signals with oscilloscope, I realized the sensor failed to acknowledgebecause the SDA line fluctuated between around VDD and VDD/2. In my program, the RH sensor receives a measurement command and a read command alternately for every 100ms. In general the signal rises to VDD after the write-bit (logic LOW) following the 7-bit address, whereas drops to about VDD/2 after the read-bit (logic HIGH) following the 7-bit address. Waveform of the SDA line fluctuation (with larger time scale), and detailed I2C SCL and impaired SDA signals are attached.

My pull-up resistors are 2.2K as suggested by the datasheet, current drawn by the RH sensor is below 1mA during I2C communication. This same I2C interface ever worked well with Sensirion SHT35 sensor. After we switched to Honeywell RH sensor, I did minor modification to the code, because Honeywell RH sensors perform measurement and return data without command, but controlled by the last bit of the first byte received from the master. The application circuit of the sensor can be find at
https://sensing.honeywell.com/index.php?ci_id=147072

and the communication document can be found at
https://sensing.honeywell.com/i2c-co...al-07jun12.pdf

Now I have a new problem with the SHT35 RH sensor after I2C pin changed into open-drain.

Since the I2C communication between Honeywell Humidlcon and the microcontroller has been solved, I would like to check if the open-drain setting works with SHT35 or not. Previously (with the above setting) when the failure occurred, it's only the RH sensor doesn't acknowledge, but now when open-drain is enabled I got fluctuation on the SDA line again and the fluctuation frequency (about 0.34ms) is not related to my data updating frequency.
The waveform is attached.

I also tried to internally pull-up the the pins and disable open-drain, again RH sensor no acknowledge


texts:
What's the best way to find out how much plastic I got in a container?

Characteristics:

It's slimey
It's liquid
It's sticky
Its electrical resistance is very very high
It's very warm(250 degrees celsius)
Sometimes it will be see-through plastic and sometimes it will be a very thick plastic with a strong color.

Extra information:

I will use a cylinder to suck X liquid plastic from the container and pour it into shapes, and I got a feeder with resin which will pour into the container. And I don't know how I'm going to tell the feeder when to feed the container because I don't know how to tell how much plastic there is in the container.

So the distance measurements doesn't have to be precise, it can be binary. As long as it works.


texts: What is exactly does it mean when someone says "memory-mapping","IO Mapping","Memory Mapped IO" & "Port Mapped IO"?

texts:
All these words become a little bit confusing to me as I am a newbie. I understand that bascially a microcontroller is processor + memory to store data(RAM) + data memory OR from where the instructions get executed(ROM/Flash) + Peripherals.

How I am supposed to visualize the mapping?
Is the mapping done on the RAM?
If yes, Isn't it memory itself? How does the processor know about it?
Is this mapping done when I switch on the Controller or is done by the person/Company that manufatured the controller?

if it is really a stupid question or a broad one, let me know. I would try to narrow in.


texts: Is UL approval required on all items sold in the USA

texts: I have a spray tan machine which I wish to sell in the USA.  I have had the machine tested by a CE test house.  Do I have to have a UL approval as well?


texts:
This is the first time I work with a PIC microcontroller. I am using the Clicker 2 for dsPIC33 board (dsPIC33EP512MU810), and so far I am trying to implement a basic programme for testing the board. In this case, I want to turn on the 2 LEDs based on the value of a push button. I am using MPLAB X with the XC16 compiler

According to the schematics, the LEDs are connected to ports RA0 and RG9, whereas the push buttons are connected to RE8 and RE9.

Right now I am able to turn ON and OFF the LEDs, but the programme does not recognize when the buttons are pressed.

It was tested both RE8 and RE9 buttons, but none of them worked. Afterwards, a wire was used for shorting directly different pins of the board, doing the same function as the buttons. It was tested with RA1, RB3, and RG8. It only worked with RA1.

The code is:

int main(void) {
    TRISA = 0xFFFE;
    TRISB = 0xFFFF;
    TRISE = 0xFFFF;
    TRISG = 0x0009;
    LATA = 0x0002;
    LATG = 0x0200;

    char pushed = 0;

    while(1)
    {

        if (PORTEbits.RE8) {
            pushed = 1;
        }
        else {
            pushed = 0;
        }

        if (pushed) {
            LATG = 0x0200;
            LATA = 0x0000;
        }
        else {
            LATG = 0x0000;
            LATA = 0x0001;
        }
    }
}


texts: What's a pigtail with regards to antennas?

texts:
Can somebody explain to me what a pigtail is with regards to antennas? I bought a 434 MHz rod antenna with an SMA plug and what I got was the antenna as expected and another short piece of wire with another SMA plug (female plug type):

Is the picture above a pigtail? What's it's usage? I was able to screw on my antenna to my 434 MHz receiver without issues and have no apparent use for this other cable...


texts: What is the absolute maximum temperature of a ceramic capacitor while not operating? (non-operational maximum)

texts:
I'm trying to determine the maximum non-operational limits of my system. The operational limits are easy to determine as they are provided in all of the datasheets for each of my components. However, a lot of my passive components do not provide non-operational or storage temperature limits. Currently my approach is to use the operational limits when no non-operational limits are provided. This means that my system is limited by ceramic capacitors (rated to +85ºC), which seems intuitively incorrect.

Ceramics are usually quite resilient to high temperatures
They have to survive soldering, which includes very high temperatures (lowest pre-heat temp I could find is 100ºC)
From what I can see in the datasheets, heat affects capacitance which I don't care about while it's off

There are a lot of capacitors in my system but the ones in question are all ceramic caps rated to +85ºC operational. The following is a datasheet for an actual cap from the system which should be representative:
cl03a104kp3nnnc capacitor datasheet
The best answers will be supported with facts and provide a method to determine the maximum non-operational temperature based on known factors (use the provided datasheet for knowns). That said, I would also appreciate a rule of thumb as a bonus. My gut feel is that as long as the solder doesn't melt the cap will be fine but I'd be happy to hear how others feel.
Follow-up: Just to be clear, when I say "non-operational" I mean that the system is assembled and in a real environment but the system is off. This is not shelf storage.


texts: Need help finding the right FFC connector

texts:
This is my first time working with FFC/FPC. I'm looking for a FFC/FPC connector to match this Micro SD card extender, just like shown on the PCB.

According to the dimensions diagram the pitch seems to be 1 mm and FPC thickness is 0.33 mm. But according to the schematic the connector's seems to be 0.5 mm pitch.

I have also asked the manufacturer of this extender what connector they use and they've sent me the datasheet (mechanical drawing). Unfortunately the drawing is mostly in Chinese. I have uploaded the datasheet here.

As shown in the connector's datasheet, the pitch is 0.5 mm, and it's meant for a FFC thickness of 0.3 mm (and not 0.33 mm).

All of this got me confused as how to choose a matching connector.
Is the FFC thickness critical ? Why do they use a 0.3 mm connector with an FFC 0.33 mm thick ?

I've been looking for the connector on digikey, it seems that I need a 0.3 - 0.33 mm FFC thickness connector, contacts on the bottom, 10 positions, 0.5 mm pitch, preferably with a "flip lock" mechanism. One of the parameters on digikey is the "Cable End Type" which can be either "Tabbed, Tapered" or "Straight, Tapered" - What does this parameter mean ? And which one do I need ?

Link to digikey filtered search.


texts:
I need an Arduino to recognize a falling edge of the pulse from +10 to -110 V. What is the best way of doing that?

My best idea for now is to use an NPN transistor and make something like this:

simulate this circuit – Schematic created using CircuitLab

This way when I have a +10V on the input, the arduino pin is HIGH. Then the -110V pulse comes, the transistor closes and the pin is pulled to the ground. The resistors values are arbitrary
for now. My questions to you electronics gurus are:
1) will this work?
2) is there a better way to accomplish what I need?

Thanks!


texts: what is Tau in this very simple circuit?

texts:
\$\tau = RC = 100 \cdot 22nF \$
or \$1000 \cdot 22nF\$? or should I add both the resistors together?


texts: How an electrolytic capacitor survives in negative half cycle?

texts:
An electrolytic capacitor  doesn't like  higher voltage at its opposite terminal i.e higher voltage should only be at positive terminal as per convention.If that so how the capacitor survives in this circuit as AC signal travels in either direction.The capacitor should die in negative cycle.Why it is not happening?

simulate this circuit – Schematic created using CircuitLab

.


texts: using usb serial converter as VDIP? arduino

texts:
There are several documents about interfacing between Arduinos and USB flash drives.

Do I have to use "VDIP1" only, or is it OK to use FTDI USB-to-serial converter?

It seems both methods can use the same FTDI chip.


texts: Why delta connections are done when the motor is required to be operated at 220V?

texts:
I am working with a tip dresser which is used for dressing the tip of the welding gun. A motor is used in that tip dresser which is used to rotate the cutter to dress the tip. There are two provisions for wiring the motor of the tip dresser one is when we want to power the motor using 400V we have to make STAR connections and if we want to operate it in 220v we need to connect it in DELTA.
So my question here is why STAR connection is chosen for 440V and why DELTA connection is required for 220v.


texts: How can i add voltage regulator to unregulated DC adaptor?

texts:
I would like to add L7809 voltage regulator to an unregulated DC adaptor,as
it is shown in the photo.
In the data sheet,there is a figure for application circuit that included 2 capacitors(bottom photo).
I understand that i need to add to the voltage output of the L7809 the 0.1uf capacitor in parallel,but do i need to add in parallel to the L7809 input the 0.33uf capacitor in addition to the existing smoothing capacitor or the already existing smoothing capacitor(which is part of the unregulated adaptor)should be connected alone to the L7809 input without the addition 0.33uf capacitor?


texts:
I'm working with an IC that can't take more than 3.3V (+/- 0.2V), including on its I/O pins. I want to control it using Arduino, but its PIN's are 5V. Now I'm wondering if I can use PWM to archieve the 3.3V by setting the correct duty cycle. It doesn't seem that good a solution since the voltage will transiently be above 5V which might harm the IC.

So what is the best solution for this? Given I need to control 6 PIN's both in and out (two PIN's are only input to the IC whereas 4 are both in/out depending on the IC's state), I would prefer something involving as few components as possible since I will need to dublicate the solution 6 times!

Given the current draw will likely be very small, I'm thinking I could use a voltage divider on each PIN (= 2 resistors) to get the 5V down to 3.3V. Is that a good solution? Or is there a better one?

Another solution could be to put a 3.3 Zener in reverse from signal to ground (after the resistor)?


texts: How to remove glued capacitor from the board?

texts:
How to remove that capacitor from the board?

capacitor http://vi-server.org/vi/_/cap1.jpg

In the question about damaged power supply I was told to use "a sharp utility knife", but it don't cut that thing (is it epoxy?). Also tried old not-so-sharp scalpel (it can punch that things if pressed hard, but not cut).

knife http://vi-server.org/vi/_/cap2.jpg

What other methods of removing it can you propose?

Update: Mission accomplished:
removed capacitor http://vi-server.org/vi/_/cap3.jpg


texts: How can I carry DC component to negative side?

texts: I made a sine wave with stm32f407VG DAC periphal. But my sine wave has DC component 1.32V. I designed high pass filter but DC component was gone. But I don't want it to be gone. How can I carry it to negative side?


texts:
At the moment I'm using an amplifier based around a NPN transistor and some resistors. Its configuration is as an emitter follower. Pin 25 supplies internal audio from a DAC on the chip.

See this schematic, on the righthand side.

This handles DC offset (offsetting the AC signal into a DC signal), overvoltage input protection, switching between internal/external audio, and output. It is a bit distorted, but it works well.

Ideally, I'd like to integrate this on to one or two IC's with the minimum space usage. It'd be nice if cost was lower, but this is not critical. (Currently component cost is around $2.50 total for all components in the audio amp, in low quantities.) Also, it would be ideal if the IC did not require a dual rail power supply.


texts: What are programmable logic ICs of different complexity used for?

texts:
Programmable logic can be implemented in your widget in many different spectrums, from burning a few gates or using a MUX to the latest FPGA with built-in microcontroller and IO peripherals, not to mention ARM's PrimeCell GPIO or other, more specific examples. For what applications are the various levels of programmable logic device complexity used? Although the grouping appear to blend together near the extremes of their definitions, I think this is an acceptable list:

PAL/PLA/GAL: Programmable Logic Array; appear to be listed as 'Embedded - PLDs' at Digikey, covering asynchronous 10/8 I/O (ATF16V8C) to 50MHz, 192 macrocell,  (CY7C341B), and are mostly reprogrammable.
CPLD: Complex Programmable Logic Device; Digikey lists them as such, available in 7.5ns 10 I/O (ATF750C) to 233 MHz, 428 I/O "CPLDs at FPGA Densities" (CY39100V484B).
FPGA: Field-Programmable Gate Array; available in 58 I/O (XC2064) to 1023 I/O BGA beasts (EP1S80F1508C7N).
FPGA with hard MCU: this is when an MCU is physically laid out in the FPGA IC, not emulated.

Wikipedia quote:

  The difference between FPGAs and CPLDs is that FPGAs are internally based on Look-up tables (LUTs) whereas CPLDs form the logic functions with sea-of-gates (e.g. sum of products). CPLDs are meant for simpler designs while FPGAs are meant for more complex designs. In general, CPLDs are a good choice for wide combinational logic applications while FPGAs are more suitable for large state machines (i.e. microprocessors).

This doesn't explain the difference between using a 233 MHz, 400 I/O CPLD and a comparable FPGA; or between a 192 macrocell PLD and a comparable CPLD. I can't grep reliable guidelines by which to narrow design options. Note that I don't currently have a specific application in mind, but have often wondered, "what would I use to do that?"

I've received excellent advice off-site regarding specific requirements, but still think this question could benefit from some examples showing preference over one family of PLDs when another may have appeared to be equally or more suitable.


texts:
I am in the design stage of a control surface that controls a remote audio DSP through ethernet.  My plan is to target FCC 15 class A.  The processor is a pic32 running at 80mhz.

First question, what are the minimum test equipment specs required for FCC verification?  Is this specifically spelled out somewhere, or is there some wiggle room in what equipment is required to do the testing?

A full CISPR compliant spectrum analyzer is out of my budget range, so it will probably come down to just doing pre compliance testing.  There are quite a few older HP analyzers in the $1200-$2000 range on ebay, or the rigol ds815.  Are there any other suggestions, or specific models that others have used and recommend for this?  Is equipment rental worth considering?


texts: I am looking into using push type solenoids to push microwave touch pad buttons. I understand that the force a solenoid exerts is dependent on stroke length. One site I was looking at listed two different stroke lengths for the same product depending on "preload". http://www.trossenrobotics.com/p/small-solenoid.aspx  How am I to alter the stroke length of the solenoid to increase the force?


texts:
This is a followup of my previous question.

Boost IC = NCV3063

Vin = 8V

Vout = 23V

Iout(max) = 250mA - (Load is a constant current circuit which is enabled at 200Hz)

Schematic

Mentioned the points where I have probed

Waveforms (Same waveform, only varying the timescale) :

Why is there a dip in output current and increase in output ripple voltage at the marked areas?

And which waveform describes the right Peak to Peak ripple voltage measurement?

This :

Or

Or


texts: Sedra and Smith Microelectronics 7th edition Example 6.12

texts:
I quote from the book: "By examining the circuit, we conclude that the two transistors Q1 and Q2 cannot be simultaneously
conducting. Thus if Q1 is on, Q2 will be off, and vice versa."

Assume β = 100.

the question is: "why can't Q1 and Q2 be conducting at the same time?"


texts: operating landline phone via mobile phone

texts:
I am making a small DIY project to operate my wired landline phone (twisted copper cable) using my mobile phone. Use cases:

Dial number on landline via mobile device.
Receive incoming landline calls via mobile.

I plan to use RaspberryPi. What device can I use to intercept calls on my wired phone and do two way manipulation? (I assume it will be an analog to digital and vice versa device, similar to a modem.)


texts: I had somebody bring in some equipment for repair and the fuse on the -32v rail of the supply was blown.  I checked the current at the junction of both of the 4.7 ohm 5W resisters and the positive side was showing 0.32A and the Negative was showing 2A which explains the blown fuse (1.6A fuse)  I tested the D8 and D12-14 and all were functioning.  Any idea what would be causing the current to be so big on the negative rail?


texts: Low amp/volt relay for microphone switching

texts:
Its that time of year when I revisit one of my old projects and try to improve it. Currently I have a small 12v PA system that has a microphone and I've added an 3.5mm auxiliary input to play music over it. Right now I'm using a 3 point switch to toggle between the two.

This is kind of annoying because I have to switch between the two manually. I'd like to change it so that when the microphone is in use, it automatically switches from the aux input. The microphone attached to the PA system has a toggle switch so I'd like to detect when its pressed and switch it over. I was thinking some sort of relay for this but I'm unsure if I can get a relay that would work at such low currents/voltages (I haven't measured it in a while but I believe its on the order of a few hundred millivolts) and if this would mess up the audio signal. Unfortunately, the microphone is permanently attached and I don't think I'd be able to insert another wire into the mic cord to use as a 12v line for a relay. I'm looking for suggestions on what I could use for this situation.

Here is a quick diagram of what I'm looking to accomplish.

I am a system similar to this:


texts: Many questions about charging a lead acid battery

texts:
Well, I have a 12V 9AH SLA Battery, and I use a 7815 + a diode in series to charge it, (I really wanted to build a charger using the L200 or the LM317 but I couldn't find any of those in my city). So, I've read "Battery University" and I ended up with more questions than before.

First, It states that the open circuit voltage of a fully charged battery is 12.65V however, mine came with an open voltage of 12.93V, (And the delivery took a whole month) was it overcharged or is it its real 100% charged open circuit voltage?

Also, I've read that the battery shouldn't reach more than 14.4V to prevent gassing, however mine even without the diode (I know it is risky without the diode if I unplug the charger) doesn't get close to that voltage, after hours of intentional "overcharge" the highest voltage that I could reach was 13.5V and it didn't go any higher. then after unplugging the charger and waited a couple of hours, I measured its open circuit voltage, which was 13V. (Which seems to be the real 100% charged voltage of this battery, as it measured 12.93V out of the box after who knows the last time that it was charged).

Also, when it is charging I wait until the current drops to 2% of its amp-hour capacity, however if I wait an hour and try to charge it again, the current jumps to 0.7 amps and stays that way for hours until it again settles down to 2%, it seems that it could keep doing that forever.

(By the way battery university states 3%, while "Lee Hart's Battery Charging Basics" states 2%, who is right? xd)

Am I destroying the battery? My meter measures temperature and the battery temp always stayed at ambient temp, even when "overcharging" it.

And finally, what is the float current of the battery? Because I want to float charge it by simply adding a resistor in series to the charger, instead of adding a bunch of diodes in series to reduce the voltage.

Right now I treat it as an old battery (even though it supposedly isn't), I wait until the current stops falling (which happens really close to 2%) and I unplug the battery, however, shouldn't an old battery open voltage be 12.9-13V?


texts: How to solder MSOP-EP package with just an iron?

texts: I have a MSOP10 package with an exposed pad. How do I solder this, if at all possible, with just my temperature controlled iron?


texts:
I have to design a circuit for a device to detect any motion in front of the device up to 2 meters. I have tried with IR reflection sensor, but couldn't achieve the range. Then, I found a circuit on the internet which works on passive detection of shadows.

So, basically it takes in the ambient light, and when there is a obstacle in front of the sensor, output is triggered.  As mentioned in the circuit about using L14F1 as sensor, I could not get that part where I am living. So, I used a a normal phototransistor with some black shielding around it. It seems to be working up to 40 cm.

Which type of sensor should I look for? What are the specifications that I need to look for this application (detect fast change in light up to 2 meters with narrow detection)?
My major problem is I do not know if this circuit works properly for fast light changes. I need to drive a DC motor at output for 5 sec whenever the sensor detects a movement up to 2 meters.
Is there any other kind of low-cost and effective sensor or method for this kind of application?

I am a beginner to this field. I am willing to learn by doing. So, any suggestions and advice is greatly appreciated.


texts: How to make a incandescent lightbulbs filament withstand shock?

texts: I want to know, is there a way to make a tungsten lightbulbs filament withstand a mass amount of thermal shock while still producing a vast amount of heat?


texts: I have a 24vac input, and want to use a NO relay so an arduino knows when the relay is closed

texts:
I had thought I could just connect the 24vac input to a relay input, and then setup a pin as an input on the arduino and be able to know that the relay had closed.  But now I'm reading that relays need a minimum current or some such, and I don't really understand how I could meet that since I'll have no load.

I know just barely enough to even be dangerous.  Am I even making sense?


texts: Compensating for offset voltage in bridge measurement before instrumentation amplifier

texts:
I'm using an instrumentation amplifier (INA118) to measure the signal from a full bridge strain gauge (tension only, all 4 resistive elements are strain gauges, slow changing (DC) signal). I'm using a single +3.3 V supply (V+ = 3.3V, V- = 0V). The common mode voltage has been set to 2.35 V based on the data sheet specs, and the gain is set to 1000. I have measured the load vs output and it is linear as expected.

I'm having issues figuring out the best way to compensate for the voltage when there is no load. The offset voltage is 0.9 mV, which when amplified is 0.9 V. This takes up a large part of the useable ADC range.

One of the methods I've found so far revolves around putting a shunt resistor in parallel with one of the legs of the strain guage, or trimming the output of the bridge with a potentiometer. The perceived issue with this is that the instrument needs to operate between -20 Celsius to +40 Celsius, and the resistor compensation will not be adequate for that entire temperature range.

Another of the methods I've found is setting Vref on the INA118 to compensate for the offset voltage. This seems like it would be fine if the offset voltage was negative, but since the voltage is positive and I'm using a single supply, it seems like I won't be able to compensate this way. Is this correct?

The last thing I've thought about trying is lowering the gain and getting a higher resolution ADC, and then doing the offset compensation in software. It would be more desirable to use the ADC that is on the microcontroller, but it seems that this option has the most temperature stability.

My question(s): Which of the options above would be the best given the temperature range constraints? Am I missing any other options? Is my understanding in each of the scenarios correct? Any input is much appreciated.


texts: Convert analog voltages to digital using 5 Volt 4bit ADC

texts:
Computer Science major here, I have some idea but not really sure about it.

I have a bunch of analog voltage readings. I need to convert them to digitized values (in volts). I am getting a 'Digital Value' through an online converter, which is in range 0 - 15. Assuming it has to do something with [2^4(bits) - 1 = 15]

Is there a formula to convert the 'Digital Value' into an output voltage (output through ADC)?
Some sample analog voltages:
-4.3, 1.2, 3.1


texts: Xbee 3 coordinator not receiving packet from router transmitting data from I2C sensor

texts:
I have an XBee 3 router connected to a BMP280 sensor, running a micropython script which is supposed to send pressure and sensor data to an XBee 3 coordinator. This is as per Chapter 4 in Beginning Sensor Networks with Xbee, Raspberry Pi and Arduino by Charles Bell.
Both XBees are running Zibgee 3.0, latest firmware.
First the XBee 3 router is reading the sensor correctly as can be seen below

The micropython script is set to run on startup
#
from machine import I2C
from bmp280 import BMP280
from time import sleep
import xbee
BMP280 address
BMP_ADDR = 0x76
Target address to send data
TARGET_64BIT_ADDR = b'\x00\x13\xA2\x00\x41\xBB\x4E\x49'
wait_time = 15 # seconds between measurements
cycles = 10 # number of repeats
bmp280 = BMP280(I2C(1, freq=100000), BMP_ADDR)
for x in range(cycles):
# Read temperature & baraometric pressure
temp_c = bmp280.temperature
pressure = bmp280.pressure
# Convert temperature to proper units
print("Temperature: %.2f Celsius" % temp_c)
temp_f = (temp_c * 9.0 / 5.0) + 32.0
print("Temperature: %.2f Fahrenheit" % temp_f)
print("Barometric Pressure: %.4f" % pressure)

# Send data to coordinator
message = "C: %.2f, F: %.2f, B: %.4f" % (temp_c, temp_f, pressure)
print("Sending: %s" % message)
try:
    xbee.transmit(TARGET_64BIT_ADDR, message)
    print("Data sent successfully")
except Exception as e:
    print("Transmit failure: %s" % str(e))

# Wait between cycles
sleep(wait_time)

I should get a Receive packet frame in the coordinator frame log but this doesn't appear even though my XBees are in the same network and communicating as can be see in the below screenshots

This is what my coordinator is receiving

I have gone over my settings, double checked the code but still can't figure out why I am not receiving the data packet containing the pressure and temperature data.


texts: Can a Spartan-3A / AN / E implement edge detection for a 5MP camera

texts:
I am thinking to go in for a FPGA starter kit, I browsed the Xilinx website and found that the Spartan 3 series were quite economical - Spartan3AN, Spartan3A and Spartan3E. The Spartan 3AN seems to be a new board.

Can the Spartan FPGA handle processing of a 5MegaPixel camera, interface would be 8bit parallel data in raw rgb, and do some edge detection 15 times a second?


texts:
I am working on a volume control board using PGA2311 and this IC needs two GNDS - analog and digital. Why does the DGND polygon not fill? The image below shows the problem:

Now I have similar problem, the polygon won't fill, any ideas? It is ANALOG +5V polygon.


texts:
I am trying to read external ADC AD7798 values using ATmega32-A controller. In the datasheet, Status register Bit 7 (SR7) indicates the conversion is finished or not:

  Ready Bit. Cleared when data is written to the data register. Set
  after the data register is read or after a period of time before the
  data register is updated with a new conversion result to indicate to
  the user not to read the conversion data. It is also set when the part
  is placed in power-down mode. The end of a conversion is indicated by
  the DOUT/RDY pin. This pin can be used as an alternative to the status
  register for monitoring the ADC for conversion data.

Now I want to write code to check if the Status register MSB (Bit7) is 0 or not. So when it is 0, only then can I issue a read command.

I have written code like this:

unsigned char CheckStatus(void)
{
            char adcStatus;
            spi(0x40);
            adcStatus = spi(0xFF);
            while((adcStatus & 0x80)!=0x80);
            return adcStatus;
}

But it is not working.

My code explanation:

Issuing the read command to read ADC status register.
Reading ADC status register value and stored in adcStatus variable.
Checking the MSB bit is not equal to 1. (I am not sure if this while loop is correct or not.)

I want to check if the Status register MSB is not equal to 1 so that I can issue the read command (0x58) to read in the ADC values. If the status register MSB is equal to 1 then I can't read ADC values.

What am I doing wrong?


texts:
i want to make a soft starter for incandescent lamp.
i have seen some magical dimmer or Russian soft start device which are not available near me.
i found some diagram of the Russian soft start device but could not find the required КР1182ПМ1 chip.
this circuit did not work first but someone commented this in that site and it worked somehow. problem is one resistor gets bloody hot and lamp does not get full brightness. probably gets only 80% bright.
i made some diy vactrol with LED and LDR and soft start the LED with ATtiny85 microcontroller. then used that LDR pins as a variable resistor of a simple triac based ac fan regulator. used the regulator in series with the lamp. and it worked well. only problem is i have to power up the microcontroller separately. i wanted something very small and to put in series with the lamp.
now recently i tried this version II and it is working. lamp gets about 95% bright i guess. main dropping resistor gets hot. i will try higher wattage resistor. otherwise its working. only problem is it not to use in series with the lamp.
if you have some useful information please let me know.
thank you


texts: Data sheet of SN74HC164 regarding the output current

texts:
On the data sheet of SN74HC164 there are two statements that I apparently don't understand:

Cover page says: ±4-mA Output Drive at 5V
Page 3 says: Continuous output current Io at Vo between 0 and Vcc = ±25mA

So which one is what?


texts: Optocoupler Issue - Not sure why it isn't working - help needed

texts:
I have used an optocoupler/isolator before in a similar circuit, can't figure out why it isn't working in this instance, any help would be much appreciated.

I am using the Siemens SFH615A, link to spec below, and the following circuit which
I am using to ground an Inhibit signal on a Servo drive.

http://docs-europe.electrocomponents.com/webdocs/009c/0900766b8009c194.pdf

Very much a newbie with electronics, any help would be great, thank you.

Inhibit line when grounded stops the servo drive from powering a connected motor.
When the line is left open the drive is enabled.
Output voltage of the Inhibit line is 3.56V.


texts: I'm getting an error while uploading my code to esp8266 via an arduino (FatalError('Failed to connect to %s: %s' % (self.CHIP_NAME, last_error)))

texts:
Arduino: 1.8.13 (Windows 10), Board: "Generic ESP8266 Module, 80 MHz, Flash, Legacy (new can return nullptr), All SSL ciphers (most compatible), dtr (aka nodemcu), 26 MHz, 40MHz, DOUT (compatible), 1MB (FS:64KB OTA:~470KB), 2, nonos-sdk 2.2.1+100 (190703), v2 Lower Memory, Disabled, None, Only Sketch, 115200"

Executable segment sizes:

IROM   : 228624          - code in flash         (default or ICACHE_FLASH_ATTR)

IRAM   : 26756   / 32768 - code in IRAM          (ICACHE_RAM_ATTR, ISRs...)

DATA   : 1248  )         - initialized variables (global, static) in RAM/HEAP

RODATA : 688   ) / 81920 - constants             (global, static) in RAM/HEAP

BSS    : 24880 )         - zeroed variables      (global, static) in RAM/HEAP

Sketch uses 257316 bytes (26%) of program storage space. Maximum is 958448 bytes.

Global variables use 26816 bytes (32%) of dynamic memory, leaving 55104 bytes for local variables. Maximum is 81920 bytes.

esptool.py v2.8

Serial port COM3

Connecting........_____....._____....._____....._____....._____....._____.....____Traceback (most recent call last):

  File "C:\Users\Reghunaath A A\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.7.2/tools/upload.py", line 65, in <module>

    esptool.main(cmdline)

  File "C:/Users/Reghunaath A A/AppData/Local/Arduino15/packages/esp8266/hardware/esp8266/2.7.2/tools/esptool\esptool.py", line 2890, in main

    esp.connect(args.before)

  File "C:/Users/Reghunaath A A/AppData/Local/Arduino15/packages/esp8266/hardware/esp8266/2.7.2/tools/esptool\esptool.py", line 483, in connect

    raise FatalError('Failed to connect to %s: %s' % (self.CHIP_NAME, last_error))

esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header

esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header

_

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

I'm getting the above stated error message while I'm trying to upload a code to esp8266 via an arduino(I've removed the ATMEGA32 from my arduino). Sometimes it gets uploaded without a problem(very rarely) but mostly the upload fails.
The code that I'm trying to upload:
void setup() {
  pinMode(LED_BUILTIN, OUTPUT);     // Initialize the LED_BUILTIN pin as an output
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, LOW);   // Turn the LED on (Note that LOW is the voltage level
  // but actually the LED is on; this is because
  // it is active low on the ESP-01)
  delay(1000);                      // Wait for a second
  digitalWrite(LED_BUILTIN, HIGH);  // Turn the LED off by making the voltage HIGH
  delay(2000);                      // Wait for two seconds (to demonstrate the active low LED)
}

My settings:

Also, I want to add one more thing when the message box says "Connecting........_____....._" during that time if i reset the esp the code starts uploading


texts: Initial states in a digital system with more than one stable state

texts:
Let's say I have a digital system of basic combinational logic with feedback (I do).  That is, the value of the gates' inputs depend in some way on the value of their outputs.

Depending on the system, particular combinations of gate inputs would be unstable, meaning that the outputs of the gates, when they have that particular combination of inputs, would propagate through the feedback path to the inputs and change the set of inputs to a different state.  This is what makes a state unstable: the fact that the system cannot remain in this state any longer than the time it takes for the signals to propagate through the feedback path and back to the inputs.

Now, let's say my system has only two stable states, with the only difference being in the state of a single input (let's call it input A).  If A is 0 (and all of the other inputs are in their "proper" configuration to be stable), the system is in stable state 0.  If A is 1 (and all other inputs are properly configured), the system is in stable state 1.

When I power up the system, is it equally likely to settle in stable state 0 or 1, or is it more likely (or perhaps certain) to be in one or the other due the way the initial power supply curve upward to +5V (and downward to 0V?) affects the logic ICs?

Is there a way to predict which state will be the initial state by just considering the construction of the system?

Is there a way for me to influence the initial state without changing the fundamental structure of the system?  For example, could I possibly use a type of pullup or pulldown resistor on input A, so I could set an initial state of +5V or 0V at A, but then allow the feedback from the other gates to control the state of A at all points after time zero?  (I'm imagining the resistor setting the voltage would happen slightly before the CMOS ICs are powered up and working to set the voltage).

I imagine that dealing with initial states is a pretty common issue, and that there's probably a pretty standard way to do this.


texts: I'm new in proteus. Unfortunately I delete components in PCB layout mode without attention. Is there any way to recover them? I can see all of components in Schematic Capture mode and my simulation works well.


texts: mathematical equation for parallel voltage dividers?

texts:
As a followup to my previous question it turns out there was more to it than I thought.  It seems that between my voltage divider and the ADC on the ESP there is a second voltage divider to step down the maximum of 3.3V from the development board to a maximum of 1V at the ESP unit.

So it actually looks like this:

simulate this circuit – Schematic created using CircuitLab

I'm told R2 in parallel with the the R3/R4 (100K/220K) divider makes the R1/R2 divider act like it was 100K and 76K at Vout such that 3.3V at the first divider yields 1.42V at Vout.  That is consistent with what I measure with a DMM.

Can the two voltage dividers as diagrammed above be expressed mathematically?  IOW, mathematically, if one voltage divider is Vout=Vin*(R2/(R1+R2)) is there an equation for two voltage dividers such as the one above?

Update:

So I've been struggling with the math and I have come the conclusion that my 50 year-old brain is definitely not what my teenage brain was when it comes to algebra.  It's not something I've needed since learning it in high school and it's gotten really dusty.  :-(  Let me apologise profusely for my rusty alegbra in advance.  But...

If R3 and R4 are fixed at 220kΩ and 100kΩ respectively and R2 will be a fixed value also (I'm not sure what yet, but it will be a value that will give me good readings on R1 for the range of values on R1 that I am interested in) and R1 will be a sensor with variable resistance (i.e. a thermistor), what is the equation to figure out the resistance of R1 given a value for R2 and a value for Vout?

For argument's sake, let's say R2 is 5.1kΩ since that's a value that has been giving me good readings in the range of temperatures on R1 that I am interested in at the moment.  But I'd like to be able to change in my equation in the future if my range of interest in R1 changes.


texts:
I am designing a DAC and have a Vin of 5V.
For the analog stage I have a couple of options :

Use an Op amp that has +5V in (low audio quality)

Use an Opamp that has +-5V in (better audio quality)
So I will use option 2 and now I have the choice betwen DC/DC convertor or a charge pump. (to make the negative rail from positive one) (both options cleaned with LDOs and PI filters)

I would like my audio to be as clean as possible , what would you recommend between those choices and why.


texts: Varying emitter base voltage of a BJT in LTspice

texts:
I am doing an assignment which has asked me to find the effect of varying \$V_{EB}\$ on paramaters such as voltage gain , current gain and input resistance for the following circuit :

I attempted this question by hooking up a voltage source like this :

But when i run the circuit , it shows "Failed to find DC Operating Point for AC analysis" .
Why it's showing such an error and how do i get to plot \$V_{EB}\$ along the x-axis ?


texts:
I did find this answer which explained why the capacitor is affected by the DC bias, however, my question is more on the application.

Let's say I have a capacitor for which I have the DC bias characteristic (Cap Charge [%] in function of DC Bias [VDC]) such as follow:

Now, let's say I set the capacitor voltage to a certain value, i.e. 5V and I try to maintain it through a feedback loop. What is the DC Bias induce? Is it 5V? What is VDC?

It may sounds like a stupid question, but I kinda struggle with the notations...


texts: Why does a multimeter show VAC on VDC power supply output?

texts:
I used my simple digital multimeter to measure the real output of several small PSU's I have got at home. They all should give just direct current and show some values in VDC mode, but the multimeter also shows nonzero values when positioned in VAC mode. But not on all power supplies. Why is this?

For example a 12 V PSU shows 12 VDC, but it also shows 25 VAC, but other 12 V PSU shows just 0.00 on VAC with just slowly alternating +/- sign. Is this some sign of imperfect PSU, a bad output capacitor, or is it that a SMPS always shows something at VAC due to its noise, while linear PSU not showing anything at VAC....?

Update:

I did more testes with various PSU's. I get around 215% of DC voltage in VAC mode on my multimeter. This applies to all PSU's I've tested except one which shows 0.00 VAC - maybe that was caused by switched polarity. It shows 0.00 when I switch probes.

I also tested wall outlet - it shows nice 225 VAC, so the multimeter seems to be working correctly when there is a real AC.


texts: What are the disadvantages of using a diode bridge for DC polarity?

texts: As far as I understand, diode bridges are mainly used to convert AC into DC, but one can also use them just to ensure an expected DC output polarity for arbitrary DC input polarity. I have some small energy devices (3V-5V, <1A) that require an expected polarity and I want to safely connect them to a power source that is likely to be used with different polarity. How do I find the right type of diode bridge and what disadvantages exist when using it? Given a safe span of input current, does the diode bridge just act like a simple resistor? If so, how high is its virtual resistance, so how much energy would I loose compared to ensuring right polarity by other means?


texts:
Shannon's Law says:

$$ C = B* log_2 \left( {1+\frac{S}{N}}\right)$$

where
C is the information-carrying capacity of the channel,
B is the bandwidth,
S is the received signal power, and
N is the noise power .

I believe that, since noise increases with distance, according to the formula above, capacity will also be negatively affected by distance.

Is this assumption correct?


texts: How to calculate the Short Circuit current of a small DC circuit?

texts:
I need to do a short circuit test for my DALI slave device. I have observed a maximum load of 140W at 210V-rms (Load current = 650 mA , PF = 0.975). I have to do a short circuit at the load side and I have no idea how much current will be in an SC.

How can I calculate the short circuit current at this point? What kind of switch I have to use for this test for a period ranging from 1 sec to 5 mins.

Thank you.


texts: Is it wise to connect a (non-latching) relay's NC in parallel with another same relay's NO to achieve a switchable NC/NO output?

texts:
As shown in the image, when the two toggle switches are closed,
will the output be NC because top relay gives NO and bottom gives NC?
Is it okay to wire like this, if not what are the possible alternative solutions?
Thank you for your time.
Truth table (for OP to complete).
A    B    Z
Off  Off  ?
Off  On   ?
On   Off  ?
On   On   ?


texts:
I am building a fuel cell with a carbon cloth cathode (this one specifically: 0.03 mg/cm² 20% Platinum on Vulcan - Carbon Cloth Electrode).

How can I wire this electrode with copper wire into a circuit? I was looking at silver epoxy but it seems to be either very expensive or have a relatively high resistance which is not great since the fuel cell will likely produce very little current/voltage. Please let me know if there is another way.


texts: What is the opposite of pulse width modulation called?

texts: If I want to control a motor by simply giving it a variable specific voltage or current, to control the RPM, not by flipping the power on and off as in pulse width modulation, what is that called?


texts:
I'm planning to design a depth camera.
I'm considering to use the following Camera with the following specs:
https://www.waveshare.com/wiki/IMX219-83_Stereo_Camera
Specification
8 Megapixels
Sensor: Sony IMX219
Resolution: 3280 × 2464 (per camera)

My plan is to integrate also an Audio facilities.
So I searched and looked for a way on how to do that and found the following chip:
https://www.cypress.com/documentation/datasheets/cyusb306x-ez-usb-cx3-mipi-csi-2-superspeed-usb-bridge-controller#res579
CYUSB306X: EZ-USB® CX3: MIPI CSI-2 to SuperSpeed USB Bridge Controller
The questions

Is it possible to integrate audio data to the same USB bus from EZ USB CX3 ?
What kind of API should I work with, like for example If I want to integrate opencv, should I use like a command based system from the UART of EZ USB and issue commands from the PC to the Camera module and return back the data on the USB bus ?
Do you suggest other options in terms of design ? easier way ?

There is for sure an interface with Jetson Kit, but I think that's useless, the Jetson only has two CSI Lanes plus it's more expensive, but maybe it's better in terms of a Good CPU and Many bytes of RAM are their. but for custom based solution is not that good ? Plus an overhead of an OS Like Linux which is not needed at all ?


texts: How does a microcontroller provide a frequency higher than its crystal frequency?

texts:
I have a microcontroller which is connected to an 8MHz crystal.

I have a schematic which has a QSPI flash IC connected to it whose clock is provide by the micro and happens to be 48MHz.

I want to understand how the 8MHz is increased to 48MHz. Is it a PLL which does this? If so how?

How can I determine the maximum frequency that the microcontroller can provide from any of its pins?


texts: Very short rise and fall time with relay

texts:
My question is related to the question here. I need very fast rise and fall time (below 2ns) and pulse width of 50ns. Load is 50ohm and voltage is 250V. I have achieved the rise time with a mercury wetted relay (700ps). But problem here is that the fall time is in range of 1.6 - 3ns.
I connected every part as directly as possible to eliminate paths which slow down the pulse.
I can see 1.6ns fall time. But it doesn't happen all the time.  Is there a way to decrease the fall time or stabilise it to have constant 1.6 ns? Or should I completely try a different relay, transmission line or maybe another way?
Transmission line is RG58 Coaxial cable.

simulate this circuit – Schematic created using CircuitLab


texts: High speed (EDR) data transfer possible with HC-05 bluetooth module?

texts:
From what I understand, the popular HC-05 bluetooth module is using a CSR BC417 controller part, which supports EDR for 2/3 Mbps modes, also up to 3Mbaud UART interface for the mcu.

Assuming the mcu is fast enough, is it possible to achieve the EDR speeds with the HC-05 module?

Thanks in advance.


texts: Do I have to consider the wire gauge of common return?

texts: I am planning on using a 9 core wire to control 8 solenoid valves. 8 for the positive and the 9th for the common return. This is my first time ever using multiple positive wires with a common return and I thought of this scenario to which I cannot find an answer: If I have 24v 1A on the eight positive wires active at the same time, will I need to make sure the return is good for 8A or 1A? Does it even matter? Or am I missing a concept completely?


texts: How to simulate a circuit with LM2576 in it?

texts:
Background: I am software engineer with a limited knowledge of electronics. This is a n00b question.

I want to design a circuit to step down DC voltage from about 24V to 12V. I have tried a 7812 linear voltage regulator but the chip heats up a lot even when attached to a heat sink.

I have now decided to use LM2575 / LM2576 instead, since they are more power efficient than the 78xx series. But these chips require some more components (like diodes, registers, etc), before they can be used to supply power. I have figured out this circuit with the help of a handbook.

I now want to run a simulation of this before I dare to fry the chips (which, btw, were quite difficult to acquire locally).

What is the best way to simulate such a circuit using free/open-source tools? I tried searching for models for LM2575/LM2576 without success.


texts:
I'd appreciate any help with identifying the connector in the photo below.

It's a button bar connector in a PSA (Peugeot/Citroen) car. Inside the brown shell there is a  2 x 5 2.54 mm pitch socket. The black thing is a lever which turns left on the brown pin when latched (the two extrusions to the right of the pin act like a part of a cog wheel against similar teeth inside the socket).

The imprinted letter seem to describe the type of plastic used, not the connector itself.


texts: understanding of UART , if two devices share a common ground. How do they get to the same voltage level for a save data transmission?

texts:
My question is related to the common ground in a UART communication.
So far, what I understand how communication in general works is: Distinguishing the voltage between two cables (one is a GND and one is the data wire).

But if they have two different grounds and two different supply voltage like for example one device has 5V and the other device has 12V.

How can they create a common ground, for a stable data transmission??


texts:
I have a DC motor that needs and works nearly 400v and 20A. I chose FDL100N50  for n-channel  mosfet also IXTK40P50P for p-channel mosfet.
I connect a 4n35 optocupler for output of every mosfet.
Are those suitable for this h bridge?

I couldn't find same caracteristics mosfet for n and p channel.

FDL100N50: 500v, 100 A, 2.5 KW , n-channel
IXTK40P50P: 500V, 40A, 890W , p-channel


texts: Can I connect TV Speakers to an interface and use them as stand alone?

texts:
A couple of months ago I broke my TV and the only thing I could kept were the internal TV speakers

The TV was an LG 55EA9800.

Now, my laptop has been giving me issues with the sound, I think the internal speakers might be broken as well, that's why I was thinking that maybe , there is a way in which I can use some sort of interface, like a universal driver board to connect the speakers to it, and use a cable to run the sound from the laptop to the interface and use the TV speakers as external sound for my laptop/any other device with an audio jack.

If possible, can you please advise which kind of board should I get considering the connector used by the speakers?

Regards,


texts:
while 555 contest is long gone, I am still debugging my device, where I already abandoned 555 itself :-)

At the moment, I am driving PC fan from an PWM (30kHz) signal from atmel uC.

I am powering P-MOSFET with a simple 1-BJT-transistor-"driver". Output is filtered with an 22uH inductor + 330uF cap. Surely I have kickback diode in place.

The problem I have is while I have 256 "levels" of PWM, I am getting most of output difference somewhere in the 1-20 range. It looks like even short pulses have the "power" to drive the fan at full power.

1) How can I make it "less" powerful? Will I have more powerful fans underpowered then?

2) On the drain of the mosfet I see some 1-3Mhz ringing with some 5V amplitude, and while it all works, I don't like it (no ringing on the source or gate). What causes it and how should I fight it?

Update:
R1 - 1kOhm
R2 - 47Ohm
MOSFET - is PMOSFET from motherboard
Diode is some medium-size Schottky one, with 0.2V drop.


texts: Finding the output resistance of this circuit

texts:
I have a BJT Darlington pair with resistances connected to the base and the emitter. I want to know its output resistance seen from collector. I drawed the circuit that needs to be solved for this:

In other words, I want to find \$R_o = \frac{v_T}{i_T}\$ in the circuit above. I tried to do nodes and mesh but I'm not getting anywhere, I don't know where to apply the equations, which currents and voltages could be useful. Any ideas?


texts: Using car charger for small sealed-type lead-acid batteries

texts:
I want to charge a couple of small (1Ah 12V) sealed-type lead-acid batteries. I have a Bosh KL 1204 car battery charger. The charger's nominal current is fixed at 2.3A, while on my batteries it is said "Initial charge current <= 0.39A.

Is it possible that I use the said charger for the said batteries? If so, what are the steps to modify the charger to suit the batteries?


texts: Designing a linker script for use with MPLAB ICD 2

texts: I need to alter the 18F452 linker script so that it allocates memory for resources used by the MPLAB ICD 2. I'm not sure how exactly to go about doing this, so could anyone please make any suggestions as to how to do this or refer me to some useful resources? Any help would be much appreciated.


texts: Powering a little microcontroller with a digital output of another chip?

texts:
I have a little PCM2704 based circuit assembled from a kit. The chip takes digital input for volume up/down but I would like to replace those with a knob.

Regardless whether the knob is attached to a potentiometer or a rotary encoder, I still need a microcontroller to translate its output to the signals that PCM2704 is expecting.

The chip itself is powered directly from its USB port by 5v, however, it requires <4v for its digital inputs. It provides 3.3v through its SSPND digital output pin (which is always on for my purposes), this is what the kit design uses to feed through the buttons and back into its input pins to control volume.

Now I'm wondering whether I can use the power from the SSPND pin to actually power something like a PIC12F675-I? I know digital outputs can't handle a lot of current but then again.. the PIC chip doesn't draw that much either. From looking at the PCM2704's spec sheet, the output current for that pin(or any digital output) is unspecified.


texts:
I have a RTC ds1307 mounted on a prototype board ( the one with 3 pin stripped ), and I'm experiencing a delay of about 5 sec/day, far too big compared to some research I did. Can that delay be caused from extra capacitance added by the prototyping board or is just the crystal?
This is the crystal I'm using.


texts: How to read the current program from an Arduino?

texts:
I acquired an Arduino PCB with an ATmega2560, already programmed with the Arduino bootloader and some program. I do have the sketch, but before fiddling with it, I'd like to backup the current binary that is in the controller. As most Arduinos, it's connected to the PC using an USB-to-serial converter connected to TX0 and RX0 and there is no ISP interface.

Apparently there is code for reading in the Arduino bootloader, but I have no idea which tool to use to access it as there is no menu item in the Arduino IDE.

What software do I need to read the program from the Arduino?


texts: What is the use of a -5V supply rail on a bench PSU?

texts: I am converting a ATX computer power supply into a bench power supply and I was wondering if I would need the -5 volts. I know I might need the -12 volts for op amps but is there any point of using a binding post for the -5 volts.


texts:
Please can somebody help in Identifying the SMD component...
Thank you
AJN I have added a pic to show where the diode is located (circled in red).
Thanks...


texts:
A while ago I came across a great deal on a reel of LM2904 op-amps. Although I certainly didn't need several thousand TSSOPs, I was able to happily convince myself that, as a family man, I would be saving money in the long run (we've all done it).

Anyway, while I love the supply, everytime I reach for one I find myself wishing it had been a reel of LM358 instead.

The LM2904 seems to be basically the same as the LM358, except where it falls slightly short in a few areas. Eg. Max Vcc. Otherwise, you have to look very closely to find any differences at all - especially when comparing against the V version (LM2904V) of the chip.

1. My question therefore is, why is the LM2904 still in full production?

What is the point of it? Why would someone choose it when the LM358 is a drop-in replacement and is arguably a little better?

2. For extra credit - why is it called LM2904? This one has always bugged me. Is this a legacy number? It seems odd to have a datasheet for the LM158, LM258, LM358, and the LM2904.

It's been a while since I last watched Sesame Street, but it reminds me of their "One of these things is not like the other" game.


texts: BNC cameras over CAT5 to powerline adapters then to DVR?

texts:
My apologies if this has been asked before.

I have four BNC cameras connected to video baluns then connected to CAT5. Each CAT5 cable from the cameras meet in a junction box and then the video signals are sent on to the DVR via another CAT5 cable run and more baluns.  This works perfectly.

However, the CAT5 run to the DVR is temporary because a permanent, neat and tidy run would be very difficult to achieve, so, my question is, instead of a CAT5 cable run from the junction box to the DVR could I use powerline adapters instead?

CAMERAS > VIDEO BALUNS > CAT5 > VIDEO WIRES (8) to RJ45 > POWERLINE ADAPTER 1

POWERLINE ADAPTER 2 > CAT5 > VIDEO BALUNS (4) > DVR

I hope I've explained everything OK.

Thanks everyone.


texts: Differential ADC reference plane - ground or midpoint?

texts:
The Microchip (ex-Atmel) ATSAMD10 has a 12-bit SAR ADC with the option to use differential input. I'm generating a virtual ground (\$V_\mathrm{mid}\$) at the midpoint (512 mV) of the reference voltage (1.024 V), with the input signal centered around that.

My question is regarding the reference plane for the analog section preceding the ADC. There is a simple 2nd order low-pass Sallen-Key for anti-aliasing, and a placeholder for another RC filter after the Sallen-Key. Should the plane beneath the analog section be ground, or \$V_\mathrm{mid}\$? My feeling is that it should be \$V_\mathrm{mid}\$ as the filters are all connected to that reference voltage. The only ground connections in that region are for the opamp power.

This is for a two layer board, currently with a ground pour on the bottom layer (green) with some \$V_\mathrm{mid}\$ traces through for routing. All the analog inputs are on the bottom of the microcontroller at the top left.

The system is not particularly demanding, but (notional, given the ADC's performance) LSB performance would be nice.

Source impedance: 18 \$\Omega\$
\$V_\mathrm{LSB}\$: 250 \$\mu V\$
\$f_c\$: 1.25 kHz
\$f_s\$: 4.096 kHz


texts: Using two power supplies to power microcontroller

texts:
I have a condition where I need to power MCU with the second source when first is not working. MCU I am using is  ATMEGA328p. The circuit is solar charge controller. I am using a battery to turn on the MCU. Battery voltage is going into LM7805 and its output (5v) is going into the VCC of MCU.

Now I also want to use the solar voltage (whenever available) to give power to MCU, so that if battery is faulty or is not working, then solar voltage will be used to power the MCU, thus at least load will on during day time.

I have the below schematic in my mind.

Now I want to know if battery is healthy and is giving voltage ~12v and during sunlight solar panel is also giving ~20v, then what will happen in this case.? Is the above design safe to use. If yes, then what type of diodes should I use.

During day time both (solar + battery) voltage will be going to the regulator, will it create any trouble.? Please help. Thanks.


texts: I was wondering if there are heating cartrdiges out there which have a characteristic curve how the heating temperature depends on the heating power. E.g. a x/y plot with the heating power in Watts as x and the temperature in °C as y. Or with the heating cartridge "assembled" in ambient air. Or do I have to characterize every single heating cartridge myself?


texts:
I am learning how to model a datapath and control design in Verilog, and I have taken an example of multiplication through repeated addition.
Following is the output I am getting:
0   x x
35  0 x
45  x x
I have taken two inputs: 17 and 5, it's output should be 85. Can someone tell me where am I going wrong?
Here is the EDA link: https://www.edaplayground.com/x/G77B
module MUL_datapath(eqz, LdA, LdB, LdP, clrP, decB, data_in, clk);

          input LdA, LdB, LdP, clrP, decB, clk;
          input [15:0] data_in;
          output eqz;
          wire [15:0] X,Y,Z,Bout,Bus;

          PIPO1 A  (X, Bus, LdA, clk);
          PIPO2 P  (Y, Z, LdP, clrP, clk);
          CNTR  B  (Bout, Bus, LdB, decB, clk);
          ADD  AD  (Z, X, Y);
          EQZ COMP (eqz, Bout);

        endmodule

        module PIPO1 (dout, din, ld, clk);

          input [15:0] din;
          input ld, clk;
          output reg [15:0] dout;

          always @ (posedge clk)
            if(ld) dout <= din;

        endmodule

    module PIPO2 (dout, din, ld, clr, clk);

      input [15:0] din;
      input ld, clr, clk;
      output reg [15:0] dout;

      always @ (posedge clk)
        if(clr) dout <= 16'b0;
        else if(ld) dout <= din;

    endmodule

    module ADD (out, in1, in2);

      input [15:0] in1, in2;
      output reg [15:0] out;

      always @ (*)
        out = in1+in2;

    endmodule

    module EQZ (eqz, data);

      input[15:0] data;
      output eqz;

      assign eqz = (data==0);

    endmodule

    module CNTR (dout, din, ld, dec, clk);

      input [15:0] din;
      input ld, dec, clk;
      output reg [15:0] dout;

      always @ (posedge clk)
        if(ld) dout <= din;
        else if(dec) dout <= dout-1;

    endmodule

    module controller (LdA, LdB, LdP, clrP, decB, done, clk, eqz, start);

      input clk, eqz, start;
      output reg LdA, LdB, LdP, clrP, decB, done;

      reg [2:0] state;
      parameter S0 = 3'b000, S1 = 3'b001, S2 = 3'b010, S3 = 3'b011, S4 = 3'b100;

      always @ (posedge clk)
        begin

          case(state)

            S0: if(start) state <= S1;
            S1: state <= S2;
            S2: state <= S3;
            S3: #2 if(eqz) state <= S4;
            S4 : state <= S4;
            default: state <= S0;

          endcase

        end

      always @ (state)
        begin

          case(state)

            S0: begin #1 LdA=0; LdB=0; LdP=0; clrP=0; decB=0; end
            S1: begin #1 LdA=1; end
            S2: begin #1 LdA=0; LdB=1; clrP=1; end
            S3: begin #1 LdB=0; LdP=1; clrP=0; decB=1; end
            S4: begin #1 done=1; LdB=0; LdP=0; decB=0; end
            default: begin #1 LdA=0; LdB=0; LdP=0; clrP=0; decB=0; end

          endcase
        end

    endmodule

    TESTBENCH:
    module MUL_test;

      reg [15:0] data_in;
      reg clk, start;
      wire done;

      MUL_datapath DP(eqz, LdA, LdB, LdP, clrP, decB, data_in, clk);
      controller CON (LdA, LdB, LdP, clrP, decB, done, clk, eqz, start);

      initial
        begin

          clk=1'b0;
          #3 start = 1'b1;
          #500 $finish;
        end

      always #5 clk=~clk;

      initial
        begin

          #17 data_in = 17;
          #10 data_in = 5;

        end

      initial
        begin

          $monitor($time, "%d %b", DP.Y, done);
          $dumpfile("mul.vcd"); $dumpvars(0, MUL_test);
        end

    endmodule


texts: Still confused about SPI implementation FIFO to buffer

texts:
Point 2 of page 16 in this document (image shown below) states that:

The contents of SPIxTXB are moved to the shift register SPIxSR

Exactly how is it moved, is it moved serially or in parallel?
I don't understand why they don't provide these implementation details...
Could someone clear this up for me please who has implemented SPI before or has documentations showing the actual electronic implementation.

Source: https://pages.hmc.edu/jspjut/class/f2013/e155/docs/Section%2023%20Serial%20Peripheral%20Interface%20(SPI).pdf