texts: What does a capacitor in parallel with a pull up resistor at the drain of a N mosfet do?

texts: I am analyzing a past design that uses a GPIO to toggle the N mosfet on and off. The resistor is just a super long winded trace on a separate board. There is a capacitor in parallel with the resistor. What is the role of the capacitor? I am having issues with this circuit since when the mosfet is OFF I am seeing the emissions goes up by 10dB compared to when the mosfet is ON. Debugging further I notice that if I remove the capacitor, the high emissions go away regardless if the mosfet is on or off. From my understanding the capacitor was there to filter out differential mode noise but it seems to be causing more issues. Just trying to understand what the role of the capacitor is there for. Thanks for the help.


texts:
Question: Design a state machine that would output the sequence 0 1 7 1 and then 1 7 1 1 7 1 and so on. A reset will make the machine go to the which outputs 0?

What I've managed to do so far:

Since the sequence has four numbers so we use two Flip Flops. And states would be: 00, 01, 11, 10

And I'm considering "reset" to be an input, so the state table would have 2^3 = 8 rows.

Present St. Input Next St. Output in Dec.
   00        0      01       0
   00        1      00       0
   01        0      10       1
   01        1      00       1
   10        0      11       7
   10        1      00       7
   11        0      01       1
   11        1      00       1

From this table, I can draw K-Maps to find out simplified equations for D_A and D_B which are going to be the inputs of two D-Type Flip-Flops. But I'm to unable figure out how to display the output?

Should I convert it to binary and use three state machines instead since 7 would be 111 and three flip-flops would be needed to store this value.

Or can I use a ROM if Size 2*3 having two address lines and 3 bit output.And burn 0, 1, 7, 1 at respective locations 00, 01, 10, 11. Or is there a better solutions? Thank you. :')


texts: Charging phones via solar battery chargers

texts:
For a school project, I want to make a solar iPhone charger (specifically for the iPhone 4) and I've spent about a week looking up stuff all over the Internet, and I'm stuck for the hundredth time. First, I had my mind set on an iPhone charger (if you're interested, it can be found here: http://www.instructables.com/id/Solar-7-up-Solar-phone-charger-in-a-bottle/%29) that basically uses a homemade 5V solar panel, which is plugged into a 3.7V 2000mAh LiPo battery, and then plugged into LiPo Rider Pro (which is apparently a lithium charge board that has a battery charge regulator and also steps up the voltage to 5V which is the required voltage for USBs). Anyways, a male to female USB cable is plugged into the LiPo Rider Pro and then you can use your iPhone USB charger to plug into the male to female USB cable to charge your phone via the LiPo battery (which is charged from the sun). I think this is how it goes... The instructable is unclear when it gets to plugging into the LiPo Rider Pro, and I've spent a long time trying to figure it out. (If anyone actually reads the instructable, feels that it's easy to explain the part about the LiPo Rider Pro, and feels inclined to do so, I would really appreciate it.)

Because of my uncertainty, I kept looking and came across another solar lithium battery iPhone charger (again, if interested: http://www.instructables.com/id/Lithium-Battery-Solar-USB-iPhone-Arduino-Charger/). I think it's very similar to the first one except this one uses a lithium battery charge controller and a DC-DC USB boosting circuit. My guess is that the LiPo Rider Pro is basically a board that includes both of these things? A 1N4001 diode is also used; use of the LiPo Rider Pro seems to make a diode unnecessary? What kind of confuses me is that the author of the first instructable calls the LiPo Rider Pro a "lithium charge board" and I kind of assumed that that's the same thing as a "lithium battery charge controller" which is used in this second instructable. The second one seems to have additional materials, and I'm unsure if that's better or worse.

So in sum, I guess my question is: what is "better", the LiPo Rider Pro (from the first instructable) or a lithium battery charge controller + a DC-DC USB boosting circuit + a 1N4001 diode (second instructable)? From my ignorant point of view, the LiPo Rider Pro seems better as it seems like an all-in-one. Yes, I've read both product descriptions, but I still don't really understand.


texts: Does SNR improve at higher sampling rates for a low pass filtered signal?

texts:
Let's say we want to extract 1Hz signal from a noisy signal by using a LPF.

And assume we have sampled it with 100Hz sampling rate.

If we would have sampled it with 1kHz sampling rate and use the same LPF would the SNR be better? Why?


texts: Can someone point me in the right direction on this beginner project?

texts:
I do not know much, if anything about electronic components but I wanted to learn.

My 90s car stereo doesn't have an AUX jack and I saw these videos:
https://www.youtube.com/watch?v=bRIswrodoM8

https://www.youtube.com/watch?v=zp-t7cl_ZSs
https://www.youtube.com/watch?v=oXYHtoTCdFY

The guy solders an Aux cable to the board of car stereos that don't have an AUX port by "hijacking" another input like Tape, FM, CD, etc.

I thought it would be a good opportunity for me to learn the very basics of electronics and how to solder.

I watched 5-10 of these vids and now understand the general concept: L/R/G from the AUX cable get soldered onto the L/R/G points on the car stereo mobo through either CD, Tape, FM, etc.

I took apart my stock Nissan Bose stereo and have been studying it for a while trying to understand with little electronic knowledge what is going on.

I'd love someone to point me in the right direction of which points would work the best for me to solder? I circled in Red. Are those the right solder points?

Here is what I think is the FM radio part of the car stereo:

If that part of the motherboard is entirely wrong, this next pic shows the Cassette Tape part of the car stereo:

There are 2 grounds though. "S-GND" and "GND", which is correct?

Full board view for ref:

Side View of board:


texts:
I am working on a project that it has to work at 2.5V-0.3mA, 12h a day during almost 2 years.
The probleme is that I don't understand something.
I did some calculation of the minimum capacity of the battery and I ended-up with some weird results.
Imagine we want a 9V battery.
We have 2.5V-0.3mA during 12h a day, it's 0.009Wh/day.
During 365 days*2 years, it's 730 days.
So finally my battery has to have a capacity of :
If I want an admissible discharge of :
- 50%, I have : 0.009*730/9/0.5 = 1.46Ah
- 80%, I have : 0.009*730/9/(1-0.8) = 3.65Ah

Wy does the battery has to have a higher capacity if I want to discharge my battery to 80% of its capacity than 50% ?EDIT :Does that mean if I take a 1.46Ah battery my system will stop to work at 50% ? Therefore at 4.5V ? I think I'm missing something...Thank you !


texts: Does running LED at higher voltage damages the LED?

texts:
I want to run 12v 6 watt LED at 19v by keeping maximum watts constant (current controlled). By doing so will damage the LED?

  I.e

  12v x 0.5000 A = 6W

  19v x 0.3157 A = 6W

update1: I am running these LED with buck based PT4115 home made led driver


texts: current mirror circuit using BJT is alternative for LM317 current source?

texts: I learnt about BJT and MOSFET current sources in my textbook,but they are used in IC chips.Is it possible to do our own current sources using BJT like two 2N2222 transistors in current mirror configuration? Does it really works fine or will have defects regarding the aspect ratio as in the case of MOSFET current sources?


texts: Designing Flash Memory to USB Mass Storage bridge

texts:
I've been scratching my head at this for a while now. I'm trying to build a device that records audio using a VS1053 encoder IC to some sort of SPI flash memory. I want to be able to download the recorded files via USB to a computer.

Currently I'm using Adafruit's breakout board to record OGG audio to a microSD card which I can plug into a computer. I would like to eventually design my own board that has the encoder IC, SPI flash memory, and the USB bridge(?). Here are the questions I have:

Can I use any type of flash memory IC like this one? 64Mbit will be enough for my application.
Existing libraries for the audio encoder output data to an SD card. Can external flash memory be configured to appear as a very low capacity SD card?
For the aforementioned USB capability I found a couple of memory controller ICs:
-Maxims MAX145002: Probably too expensive for my application (~$20)
-Microchip's USB4640: Reasonably priced (~$3)
Will these memory controllers work with SPI flash memory?

Also if it helps to know, this is a for a prototype of a device that will enter low volume production (100s to 1000s).


texts: ULN2803 behavior when its output is not connected to any load in this circuit?

texts:
I'm studying the a circuit that is using a driver ULN2803 datashet. The driver is needed for external loads as LEDs when a pin is writing. The situation that I would like to talk about is when the pin is reading. As the GPIO interface is MCP23s17 datasheet, when pin is an input, pin gets Z state.
To explain the enterely application could be a mess, I will try focusing the description on the doubt about ULN2803 behavior within the circuit.
I'm new using it. I have used it for inductive loads, as relays, application once before. I thought I understood the most of this device. But after working with this circuit I realize that I miss some important things.

simulate this circuit – Schematic created using CircuitLab
I think the most important involved circuit is inside the green box.
Maybe the circuit is not functional for what I need. But I was analyizing it over the paper and set on my breadboard and I don't get it of all. So I took some values. I'm studying the value at M node when the output driver pin 'OUT_C' (OUT_C = IN_1) is not connected, so Z.
The following values can be seen:

V at (driver output) OutC = VCE = IN_1 = 2.4V
V at M node = 1.5V (driver input)
V at Diode IN4004 Anode = 2.9V

What I did not understand was how 1.4~1.5V were there (driver input). I actually need input driver to be having about 3V. I'm sure the device is working correctly and who was wrong it's me. The resistor values were firstly calculated in order to have V = 3.3V at M node if driver was OFF. I thought that if driver was OFF, no current drive, so it could be 3.3V at M node. Obviously I don't see that. But I need to understand these questions:

I guess the driver is ON but if it was, Vin(ON) = 2.4V. Maybe it is not.
How can M node achieve 1.5V. I don't see it. I even take into account internal driver resistors but I don't get 1.5V.
I don't see why Vdiode = 2.9V
I guess VCE = Vdiode - Vd = 2.9 - 0.6 = 2.3V

Feel free for answering where the mistakes are and tell me what is wrong.


texts: Isolated bidirectional Buck/Boost transformer

texts:
I'm trying to develop a bidirectional DC/DC converter for cell balancing.

Here is the schematic in PSIM:

In the picture you can see a digital PI controller implemented in a C block controlling the boost Mosfet, while the buck Mosfet is off. The controller is checking the inductor current and controlling the duty cycle so that its average value is 3A. The switching frequency is 30kHz. The simulation works flawlessly.

I've used the techniques described in the book "Fundamentals of power electronics" to get the inductance and capacitance values needed for the normal, non-isolated boost and buck converters, since the addition of the transformer shouldn't change the dynamics of the converter if it is a 1:1 transformer. The values of inductance and capacitance in the schematic are the worst case scenarios for the tolerances given by the manufacturers of the components I choose.

Now, since I'm boosting from 3.0V to 48V, a 1:8 transformer would allow for decent duty cyle values (in the 40%-60% range), but I'm having trouble finding a good transformer for this. The transformer in this link looks like it would be a good fit for the job, since the secondary sides could be paralleled. The problem I'm faced with is that the transformer doesn't list its maximum voltage on the primary and secondary sides, so I'm worried that the secondary side might not be able to handle the 48V from the battery.

So, my question is:

Is that transformer a good fit for this design? If so, how do you know that? Can you somehow calculate the maximum voltage that the primary and secondary sides can take? If this transformer is not appropriate, could you help me find a good fit for this design? If possible, include calculations to clarify how to choose a proper transformer.

Any help would be immensely appreciated!


texts: Is it probable that a 15VDC device be damaged by a 14-16VDC battery?

texts:
I have a KBD101 (a brushless motor controller from Thorlabs) that, in the manual, specifies a regulated 15V/2A supply.  I need to power it from a 14.4V/10A Li-ion battery.  The other electronics are rated at 12V and are protected by LDO regulators but my understanding is that I can't do that for the KBD101 because the voltage from the battery is going to vary between 16-14V as it discharges.

How likely is it that the device will work reliably with this varying voltage?  I've connected it to a bench supply at 15V and it draws 300mA during the experiment.

I've asked Thorlabs but, understandably, they can't recommend such a use-case.

Thanks in advance!


texts: How does this direct digital synthesis accumulator work?

texts:
So, I grabbed some code online and morphed it to work with my DE2-115 board, and now I need some help understanding exactly how it works.

DDS_accum <= DDS_accum + 32'h16FC7BBC +
    ((256+((message[15]==0)? message[15:7]+256 : message[15:7]-256))<<15) ; // "audio input"

I need help understand exactly why the above Verilog HDL line exists.
The large block of code shown below is to show you where it's implemented.

This is the main block of my Senior Design Project, but, my major at college teaches me about software and hardware, not so much Frequency Modulation. So, a lot of this is going right over my head.

I've read through this and some wikipedia pages and some youtube videos, but, I just don't understand the point of the constant and playing with the message signal in the line above.

//make a direct digital synthesis accumulator
// and output a 10-bit sine wave to the VGA plug
// set carrier frequency to 1 MHz DDS_incr = 32'h51EB84C = 85,899,340
// 11 MHz 32'h3851DCA8 = 944889000
// 9 MHz 2DF8F778 (771291000) : 4.5 16FC7BBC (385,645,500)
// 7 Mhz 274AF224 (659223076)
// set modulation to 400 Hz 85E7

// This outputs at 146.0 MHz.

always @ (posedge CLOCK_50) begin
    //generate 4.5 Mhz square wave carrier with FM modulation
// 32'h16FC7BBC = 385645500
    DDS_accum <= DDS_accum + 32'h16FC7BBC +
    ((256+((message[15]==0)? message[15:7]+256 : message[15:7]-256))<<15) ; // "audio input"
    end

    //hook up the ROM table for carrier
    sqwave sqTable(CLOCK_50, DDS_accum[31:24], sq_out);

    //use the VGA DAC for an FM modulated RF signal
    assign VGA_R = sq_out;
    assign VGA_SYNC = 1 ;
    assign VGA_BLANK = 1 ;
endmodule

//////////////////////////////////////////////////
// Square wave table for the DDS
module sqwave (clock, address, sq);
    input clock;
    input [7:0] address;
    output [7:0] sq; // changed to 7:0
    reg [7:0] sq;    // changed to 7:0
    always @ (posedge clock)
    begin
        sq <= (address<128)? 8'h7f : 8'h01 ; // changed
    end
endmodule
///////////////////////////////////////////////////

I apologize for the large block of code, but that's the heart of this FM Transmitter. This code modulates a 24-bit input audio signal from the Line In port and out the VGA_R port as an FM signal at around 146.0 MHz.


texts:
There's a DC Black Box, and my goal is find the Thevenin resistance within the black box. By connecting a digital mulitmeter to the terminal, I have found that the "open-circuit" output is \$0.647\ \text{V}\$. Then I connected a variable resistance box and the multimeter in parallel to the black box. Then I increased the load resistance to \$1410\ \Omega\$ till I got 50% of the open circuit reading. Which is \$0.3235\ \text{V}\$.

Then I know that \$V=I\cdot R_{th}\$

I proceeded to find \$I\$ by using the relationship created by the load,
\$0.3235 = I\cdot 1410 \rightarrow
I = 0.000230780142\ \text{A}\$

Then using this value I solved for \$R_{th}\$

\$0.647 = 0.000230780142\cdot R_{th} \rightarrow R_{th} = 2803 \Omega.\$

Then I was allowed to check the Black Box contents and the circuit looked like this:

Shouldn't the effective resistance then be,
\$R = R_3 + (\frac{1}{R_1} + \frac{1}{R_2})\$?

This doesn't even come close my calculation.

Any help would be greatly appreciated.


texts: What can I use for temporary wiring harness?

texts:
I was a computer science major in college, and dabbled in EE related stuff where necessary for coursework, but I'm working on a small Arduino project for Halloween and need some advice.

I've got an Arduino Uno board hooked up to two full color LED's in parallel.  When complete, these LED's act as eyes mounted inside a head.  Obviously right now they're just connected on a breadboard, but I will need to wire them together so that they can be mounted inside the head appropriately.  I have no experience using a soldering iron, and I'd rather avoid it since it's a lot of overhead work a project this small.

Are there any parts that I can buy that can clamp wires to the leads on the LED's?  For instance, I'd like to cut and strip some wire so that it can be plugged into the Arduino pins and clamp the other end to the LED leads.  If so, where can I buy them?  That way I can take things apart when no longer necessary.


texts:
I'd like to monitor the power usage of a number of single phase mains devices (0-10A). The system is to be added to an industrial automation system (on DIN rail), and should be able to talk to a microcontroller (analogue or digitally).

It can be installed inline or around the cable (ie clamped). What are the advantages of each?

I'd like to know about the method used for current/power measurement, the accuracy (for a 0-10A range), a suitable off the shelf system/parts, and a rough cost.

To clarify:

I'm interested in using an off-the-shelf system if at all possible. If there's an existing solution that suits my needs, I'd love to hear about it (and answers to the questions above - how it works, accuracy, cost). There's no sense redesigning the wheel here, it's not an academic exercise.


texts: Transformer circuit, equivalent impedance

texts:
Having trouble with a circuit on my problem set and was wondering if anyone wanted to give me a push.

The ideal transformers winding relationship N1/N2 can be varied, as can the capacitance.

Decide the optimal ratio and the optimal value for the capacitance in order to maximize power dissipation in R2.

We were given a hint to use the relationship

$$Z' = Z(\frac{N1}{N2})^2$$

Where Z is the impedance of the circuit to the right, and I'm assuming Z' is the impedance of the left circuit. But if these are the sans-tranformer impedances or if the transformer is affecting them, I don't know.

Grateful for a push...


texts: How to use SysTick_Handler (an HAL library function) in order to have a time base

texts:
In actual I need to measure speed of motor.
I have followed a procedure, i.e

use Encoder mode to get pulses from sensor.
count number of these pulses in 1 sec~1000msec using SysTick_Handler(ISR). Means use SysTick_Handler function as a time base to count pulses in 1000msec.

Now, I am bit confused about how to encorporate step no. 2 in codes. Because I have been taught that Systick Handler(ISR) is called every 1 millisecond. And if it is so, while passing through lines of codes inside Handler, will the duration of 1 millisecond sec not get passed. Will the Systick_Handler not get called again before even completely counting for 1 millisecond. Also, how do I make sure that the Systick_Handler counts for only one second and then again starts counting afresh after duration of 1 sec gets over.

This is the Handler function.

void SysTick_Handler(void)
{
  HAL_IncTick();
  HAL_SYSTICK_IRQHandler();
  Encoder_Start();                     //encoder mode start

  counter=Encoder_Read(void);          //reading counter(defined globally and shared by handler and main)

  Encoder_Stop();                      //encoder mode stop

}

And this is the main

    main.c
    .
    .
    .
    uint32_t Encoder_Read(void)         //reads counts from sensor
    {
        return TIM3->CNT;
    }

    void Encoder_Start(void)
    {
        HAL_TIM_Encoder_Start(&htim3, TIM_CHANNEL_ALL);
    }

    void Encoder_Stop(void)
    {
        HAL_TIM_Encoder_Stop(&htim3, TIM_CHANNEL_ALL);
    }
    main()
{
 .
 .
    while()
    {
      speed=counter*constant;              //speed, counter is used here

      printf("\n%d",speed);                //print speed using semihosting on eclipse
      PWM code;
      PWM code;
      PWM code;
    }
.
.
}

My original question was this

Development board is STM32F407, OS is Linux(Ubuntu), code is generated using STM32CubeMX.

Any ideas about this?

Or any other alternative, I need to have a time base of 1 sec to measure the number of counts from sensor(LM393 based) and use this time base again and again to measure the speed and display it every second.


texts: How much voltage difference will lead to saturation, LM741?

texts: Which parameter should I look for? I want to know what should be ( Vin+ - Vin- ) to get a saturated output.


texts: Control color of Bi-Color LED using Arduino

texts:
I have this push-button switch which has two solder lugs for 12 VDC power and will illuminate red or green depending on the polarity of the wiring. It may not actually use a bi-color LED, but it seems to be a good representation for how it works. I can't find a schematic for the switch, though I expect it may be something like this:

I'm providing the 12V using an LM7812C voltage regulator but I'm struggling to figure out how I could control the polarity of the applied voltage using an Arduino. My idea is to have an Arduino control a MOSFET to switch power to the LED, though I get lost trying to find a way to flip polarity.

Is there a way I could control the LED to be red, green, or off using outputs from the Arduino?

Or alternatively, just have the switch default to one color and switch to the other when triggered by an output from the Arduino?

Thank you!


texts: 12V Relay Voltage Surge on contact close

texts:
I'm designing a pcb relay circuit to switch on/off power to an inductive load on a 12V line. I'm using an SPST-NO relay (omron relay) to switch the circuit open and closed, and I'm having trouble tracking down a high-frequency (~10MHz) +5V voltage spike seen when the switch closes. Any advice on how to clean up the initial power on signal? Oscilloscope attached, note the voltage divisions are 5V and the time divisions are at 500ns.

I've tried connecting a TVS diode in parallel with the inductive load with no success. Happy to include a schematic if it's useful. Any advice would be much appreciated.

Thanks


texts: Voltages to keep my circuit running at 200mA with NMOSFETS

texts:
Im trying to build a circuit to send information using IR led, using pulse signals
my leds (TSAL6400) operates at 1.35V, and their maximum pulse current is rated 200mA

After struggling a bit with BJT transistors, and realizing that since I'll send the data using RPI (Gpio is 3.3V, 16mA), I switched to NMOS transistors.
I found a local dealer with RFP30N06LE

Vgs(th)= 1-2V (min,max)
Rds(on)=0.047Ohm

My circuit (due to other limitations, and the fact I need to decide on which branch of leds to send the command on, each branch is a different room in my home)

As I demonstrated in this sketch, each of the branches represents a room, and I want to each time send a command to a specified room.
So, for instance, to send to the second branch from the left, I will turn the M2 on ("1" = 3.3V of my gpio at 16mA max), and will send the pulses by turning on and off M5
In order to reach 200mA I need a total voltage drop of 2.3V over my resistors and transistors.
If R1=11.5Ohm, for M1-M4: Vds=0V, Vgs=3.3V
Since Vds=0V will keep the transistor closed (no current flow), I assume I need to raise the voltage just a bit, but not sure how to make it appropriate for case with two transistors, one after the other.
If I will use Rtot=8.5Ohm + 1.5Ohm + 1.5Ohm, and placing R1 where it is already, R2=1.5Ohm before M5 and another one after. Is that the correct way?
This way:
Vgs(M2)=3V
Vds(M2)=0.3V
Vgs(M5)=3V
Vds(M5)=0.3V

Is that correct?


texts: What kind of power supply should I be using to power the incandescent bulb inside the Big Dome Push Button?

texts:
I have a Big Dome Push Button as the activation switch for a photo booth project I'm working on. The problem is, I don't know how to power the incandescent bulb inside of it. I don't want to do anything complicated, I just want the bulb to always be illuminated.

The button has two pieces: the switch and the bulb. I have the switch successfully hooked up to an Arduino that's controlling the camera, so now all I need to do is power the bulb. The specs say that it's a T-3.75 12VDC@1.2watts incandescent bulb.

Is there some sort of battery I can use? Or do I need a power supply? I have a few 12v power supplies sitting around but how can I tell if they're too much current?

This is probably a really basic question, but I've been googling for an hour now and haven't found anything that makes sense to me yet.


texts: As far as i have read v(rms) is a dc value and i(rms) is also a dc value and apparent power is multiplication of both of them.so,can apparent power be represented as dc power absorbed by an ac circuit.am i guessing right?


texts: Newbie on SMD. From THM to SMD PCB design and manufacturing

texts:
I have made a prototype of a device using THM technology. Now one of my successful friends has suggested me to move the design to SMD technology to reduce component and PCB manufacturing costs. I have started struggling and tried to research what's best to do but still not happy.

1) A PCB Design Tool with a rich library as in ready to use (better than Proteus at least, I have tried Altium as well but still not happy) so I don't have to struggle every time to find the footprint, model, design, measures and so on (real pain sometimes or anyway quite annoying for many devices).

2) How do you choose which manufacturer and which package to use? (there are too many)

3) Do you really need reflow-oven for QFN (microcontrollers)?

4)Sometimes SMD components have so many different versions/codes just because of their different ordering packaging type and it just makes it hard to take a decision.

Any further suggestion would be good. Thanks anyone for their time.


texts: How can a boost PFC (Vienna rectifier) lower the voltage?

texts:
I found a Vienna rectifier circuit as a PFC.

Output range: +350...+500VDC and -350...-500VDC.
Input: 400VAC (three phases).
To begin with, I simulated a basic three-phase rectifier:

Here's the 561V output.
This is more than the 350V minimum from the Vienna rectifier.
I concluded that the Vienna rectifier has a buck mode in addition to boost mode. But before that, I already received an answer that the Vienna rectifier works only in Boost mode.
After that, I got stuck. It is not clear to me how this circuit can provide a drop to 350V when entering 400VAC.
The only thing I assumed is that two series capacitors with a midpoint - form a voltage divider.
Almost everywhere where the Vienna rectifier circuit is shown - only the maximum output voltage is indicated, the minimum I saw only in this circuit.
Questions:

How is the output voltage drop achieved in this topology?
The maximum output is 500VDC, but I have seen identical circuits with outputs of 750 VDC, 840 VDC and more. Does the value of the input inductances affect here? Or is this voltage limited only by the parameters of the components (switches, diodes, capacitors)?

Thank you!


texts: How can I improve the response time of a low pass filter?

texts:
I am busy with a high order low pass filter. How can I improve the response time of a filter? If I use a higher ordered filter, does it improve? Also, if I use an op amp with a faster slew rate, does it improve?

My application is that amplify and get filter the load cell signal. My load cell signal is changing between 1 Hz to 10 Hz.

There is three stages in my signal conditioning circuit. First stage Instrumentation Amplifier to amplify the signal(AD8221), second stage is second order low pass filter with OP07C op-amp (Sallen-Key type, corner frequency is 10 Hz), third stage is voltage follower with again OP07C.

According to my test results, when I compared original signal to output of amplifier (first stage) there was no significant delay between two signals. However when I compared original signal to output of voltage follower there was significant delay. The delay was approximately quarter of a period of original signal.

So I have thought that I have to improve my filter rise time. Or do I have to change my op-amp with higher slew rate one. According to all your answer, should I use higher cutoff frequecy with same op-amp (OP07C)?

Most of you mentioned "group delay" of a filter. What does "group delay" depend on? I got it firstly depends on corner frequency of a filter. Is there any effect order of filter to group delay?


texts: What is the probability of a bit error occurring in modern computers?

texts:
What is the probability of a bit error occuring when reading/writing from/to the latest memory technologies (ssd, hdd, ram) in modern computers? If the same terminology is used in this context as in networking/communication systems, then my question can be rephrased as:

  What is the bit error rate(BER) when accessing memory either to read/write in modern computers?

As a follow up question, how do computers deal with such bit errors?


texts:
I wish to control a programmable power supply to deliver constant power (watts) into a heater. The heater resistance varies from unit to unit due to manufacturing tolerances.

The PSU has a 'programmable' or remote setpoint input. 0 - 10 V gives zero to maximum voltage.
The PSU has two feedback signals - one for output voltage and one for output current. These are 0 - 10 V signals scaled zero to maximum.

I'm wondering about the following approach to provide a solution.

simulate this circuit – Schematic created using CircuitLab

The analog multiplier MUL1 gives an output proportional to the product of the voltage and current.
Op-amp OA1 compares the power level feedback with the power level setpoint (R3) and adjusts the voltage setpoint until the output power equals the setpoint.
R1 and R2 set the gain of the response.
C1 provides some filtering to reduce noise.

I only need a single quadrant multiplier as both feedback signals are positive. This raises the hope that I could find a single (positive) supply multiplier chip that with an output range of 0 - 10 V.

Q1: Are there any obvious problems with this approach?

Q2: I can't find a single-quadrant multiplier. (I've used the AD633 four-quadrant multipliers before.) Does anyone know of any?

Update 1

The PSU voltage setpoint has an RC filter with protection zener on it. R is 1k and the time constant is about 1 - 2 ms so C is about 1 uF.
The heater will be turned on for a second or so every five or six seconds.
A power supply rise time to 95% voltage of 50 ms or so would be adequate.


texts: Choosing "pull down" resistors for automotive diode logic XOR gate

texts:
Thanks to some members on here I finally managed to understand how a bridge rectifier can be used as a diode logic XOR gate in an automotive application. Now I'm trying to figure out how to select the "pull down" resistors. The bridge rectifiers I'm looking at are all rated at over 100V peak reverse voltage and 10A or more forward current, so I'm pretty sure they should be fine. But what I don't know is how to figure out an appropriate rating for the resistors. Thank you for any help!

simulate this circuit – Schematic created using CircuitLab

I'm not worried about R3, just R1 and R2.


texts:
I have a switch circuit which works with two phases. I need a flyback SMPS power supply for my logic circuit. I want my control circuit to be alive if any or both phases are receiving power. This can be achieved if my bulk DC capacitor receives power from both phases simultaneously. Currently, my power circuit receives power from a single phase like this:

To add the second phase, I am planning to do this:

Will it work? I think it should because the capacitor's voltage will block any voltage lower than it's voltage right behind the diode itself, at any point of time.

Or, am I wrong? At the bulk capacitor, will there be two voltages fighting each other?

In case it works, can I do something like this:

I have removed the redundant neutral supply in the bottom rectifier, thereby saving me two diodes.

Besides this, is there anything else that I am missing out? Will the voltage on capacitor remain same whether single or both phases are supplying power or will it differ?

EDIT:

After looking at the answers, I realize that if I use full bridge rectifiers as I shown in previous images, peak output on bulk capacitor will increase significantly depending upon the phase difference of the voltages. This increase will create difficulty due to these two reasons:

1) Higher voltage means a higher voltage rated capacitor

2) It might get difficult to find a flyback IC which operates at this high voltage.

3) Even if capacitor and IC are available, it might be costlier as compared to what I can use with a lower voltage which I get in 1 phase design.

As such, I can think of another option. Using half bridge rectifiers to rectify each phase and use Neutral line as my reference:

Since my output power requirement is less than 5 watts (1-2 watts typical), I feel that half bridge will work even when only a single phase is available. This also ensures that my bulk capacitor will not see a voltage higher than sqrt(2)*220 V = 311 V peak. In worst case where Vrms = 270V, it will give 382 V peak. Thus I don't need to modify my existing single phase power supply circuit after the bulk capacitor.

Am I right in thinking so? Is there any better way to do this?


texts: 16MHz Crystal with 2p load capacity: What load capacitors are necessary

texts:
I found a nice and cheap crystal on AliExpress which I want to use with my ATMEGA328 microcontroller.

Its load capacity is only 2pF. Normally I would say, that the 2 capacitors from the crystal to ground with 4pF should work fine. But isn't the parasitic capacity of the soldered part that high, that maybe no additional capacitors are needed?

Is exactly this the idea of a crystal with 2pF load capacity, that no additional capacitors are needed?

I do not have an oscilloscope, because of which it is difficult for me to test when it is oscillating.


texts: Trouble Driving a Solenoid with a LiPo Battery

texts:
I am having trouble getting enough current to drive a bi-directional solenoid with two leads. I am using a half of a L293 (Quadruple Half-H Driver) to drive the solenoid back and forth. The solenoid has to overcome some stiction so it barely flinches if there isn't enough current. I have gotten it to work, albeit slowly, with two standard 9V batteries in series.

I didn't think the two 9V batteried were pumping out enough current, so I switched over to a 11.1V, 5000mAh - 35C LiPo battery. This battery should be overkill but it's still not driving the solenoid as fast as it needs to.

In the diagram below, VCC2 is the connected to the positive terminal of the battery. Pins 2 and 7 (driver inputs) are connected to a LM556 dual timer circuit (shown below) which creates a timed pulse and only allows one of these pins to be high at a time. The switching circuit works well.

Questions:
 1. Is there some way I can further boost the current going to the
    solenoid?

Do I need a flyback diode on the solenoid? If so, how do I do that with a bi-directional solenoid which only has two terminals?
Is there a simpler circuit that will get the job done?

It's also worthy noting that since I'm using a breadboard and can't properly heat sink the L293, have to unplug after using it a few times. Two times now, it has gotten hot and the circuit oscillates after one of the buttons is pressed. After it cools down, everything works again, so I don't think I let the magic blue smoke out of anything ... yet.


texts: Number of independent KCL and KVL equations with practical example

texts:
The expressions

\$N-1=\# KCL \$

and

\$E-N+1=\# KVL \$

(where \$N\$=number of nodes; \$E\$=number of elements on the circuits) gives us the linear independent equations on a circuit.

Per example:

Here I have 8 nodes and 10 elements, so I got 7 independent KCL equations and 3 independent KVL equations, but I only want to know I,I1,I2,I3,I4,I5, so I just have 6 unknowns.
So my doubts are:

Why I have more equations that unknowns? I only have 6 unknowns.

What are the 7 KCL independent equations?

How can I select the 7 KCL equations in order to don't get dependent
equations?


texts: Equivalent Characteristic Impedance for Different Trace Widths

texts:
Suppose I have a PCB trace that needs to be impedance matched, but the trace width changes as it travels from its source to its destination.  Something like this:

The 5mil trace would have a certain characteristic impedance, whereas the 10mil trace would have another impedance.  How do these two different impedances combine?  Asked differently, what is the equivalent impedance of this trace?


texts: Atmega328p connected to an NRF24L01+ not working

texts:
I've been working on a project for some time right now, I'm trying to make a modular sensor system with atmega's and nrf24 nodes. I've made a custom pcb but it isn't working. I've tried a lot of things. Could somebody take a look please?

Thanks in advance,
Stefan Nienhuis

Schematic:

Edit:

I have done some edits to my original schematics. How does this look?

New schematic:


texts: AL8860 LED driver does not output required constant current

texts:
The LED driver circuit i've made here does not output a constant 1A current.

With an input voltage of 12V and 9V total Vf on the three LEDs (CREE LED star), the current is only 0.65A. Am I understanding the datasheet correctly? If so, the AL8860 should output 1A with a 0.1 ohm resistor across the Vin - SET pins (Iout = 0.1/Rs).

When testing on a power supply, I set the voltage limit to 12V and increase the current from 0. The voltage starts at 7V and increases as the current increases until it hits 12V between 1.1 and 1.2A. The power supply will then switch to voltage limiting and the current will drop to 0.65A, staying at 12V. As I then drop the current limit down, it switches back to current limiting at 0.8A, the voltage then changes from 12V to 8-9V.

I'm sorry for the convoluted explanation of my testing but I cannot understand what is happening here. The PCB and components are all correct.

Note: The MOSFET is not currently in the physical design.


texts:
How to calculate the optimal distance between an anode and cathode?
If I am making a fuel cell, how can I determine the best distance for best conductivity between the two electrodes (anode & cathode?)
How can I determine the ratio between their surface area (their size) for (bio-fuel cells, chemical fuel cells, anything?)


texts: Altium Library Issues- Replace uknown schematic library with know library

texts:
I am using Altium 20.1 and my question is regarding the sch library. I generated a schematic library and I want to use that as my default library for the components.
When I try to update the schematic symbol, I see 2 sets of libraries :
1- imxbb.SCHLIB (unknown path. Is there a way to find it?)
2. IMX53_BB_1v2.SCHLIB (The one i generated and want to use)

I cannot add parameters to components because imxbb.SCHLIB does not show in the project tab


texts: Current Monitoring circuit setup and option exploration for IoT device testing

texts:
I would like to use the ADA4528 opamp or similar opamp to monitor current consumption across a sense resistor for an IoT device but with a Caveat. I want to measure the entire range with one setup/setting

Project: To create a current sensing instrument that I can use to plot the entire Transmission window of a battery power IoT device. To this far iv used different tools on the different current setting and then I add it all up afterward. This is time-consuming and often think small energy savings made in code is not visible due to set up at different current levels.

Parameters: Range required is from 1uA to 200mA (I would like to get nA). System to be powered via USB. so max supply for OpAMP will be 5v unless boosted but would like to avoid if possible. Only DC currents to be measured.

The first thought and one of the questions. if A low tolerance thermal stable resistor is used like a 0.1R is it even practically possible to measure nA at a current of 1uA over that resistor or would other factors dominate.

Second thought, if my first thought is unfeasible then how about a compensation system. Most IoT devices run at 3.6V or lower. So using a 5v LDO or switching setup to step down as the supply. Will it be possible to use a higher value sense resistor like 1R and when the current gets close to the 100mA to 200mA mark the feedback pin of the LDO would tell the PSU to compensate for the voltage drop across the resistor to keep the system voltage stable.

If this could work it will allow the output to be fed into a scope or ADC and record the entire event as a single test. Maybe an entire Soc like the ADS8681 could be a nice solution

Thanx in advance


texts:
What is the simplest and cheaper way to have 3.3V 0.5A from 4V?

I'm developing a board which uses a SIM800 so it must have 4V 2A power input from 24V external power supply (I'm using a LM2596S adj, able to supply 4V 3A). SIM800 has 4V Vdd and 3.3V logical input/output.

The rest of the board (microcontroller, etc) needs 3.3V, so I want to take it from the 4V (because if I take it from 24V I would need another step-down converter... and that means more components and cash).

The cheap AMS1117 has 1V dropout voltage, so it's not suitable.
The cheap MCP1700 has only 250mA output current.

What's about to use diodes to get this voltage?
There is another cheap regulator with less than 0.7V dropout voltage?

3.3V 500mA is needed (STM32 Cortex M0 + wiznet w5500 + some leds...). Efficiency is not a problem (AC power)

Solution:

I will take diode voltage drop as the simplest solution versus cost.


texts:
I wrote the following code:
module mul3 (
    input logic[1:0] d
);
mul3_op[0]=d[0];
endmodule;

But when I run it using Modelsim I get the following messages:

Error: (vlog-13069) mul3.sv(21): near "[": syntax error, unexpected
'['.

Error: mul3.sv(21): (vlog-13205) Syntax error found in the
scope following 'mul3_op'. Is there a missing '::'?

Please note that line 21 is actually the last line before endmodule in the code above. Any idea of what is wrong?


texts:
We have a control unit used in marine applications running of 12V nominal voltage with a current consumption of about 1A.

Today we are using a P-Channel MOSFET with some added circuitry (Zener, capacitors and a resistor) as polarity protection.

We want to implement a good power ORing solution and without adding to much cost we were thinking to use the exact same circuit for the second power input.

There are much litterature on using N-channel MOSFETS instead for lower RDs on etc. But since we now have a good tested solution using P-channel we want to try and reuse this as much as possible.

Are there any reason why this circuit would not function well? Or any other aspects of it we haven’t thought of?

See picture for schematic.

Thank you.

EDIT:
After reviewing the feedback on this post we have taken the solution in a slightly different direction to a Smart Diode Controller controlling an N-Channel MOSFET. This effectively shuts down the MOSFET in a reverse voltage scenario.

We now have two of these circuits in a power ORing configuration and the TVS is now bidirectional.


texts: Why are thermionic valve/tube heaters generally designed to be 6.3 V?

texts:
Why are the heaters generally 6.3 V (or multiples thereof)?

Does it make for an easy transformer winding ratio when used in countries with 120 VAC or 240 VAC mains?

They often pull quite significant current, and as there's generally a higher voltage supply available, a higher voltage and thinner wire could have been used.

What are the advantages of having a low voltage supply for the heaters?


texts: Driving one LED from audio signal only with pnp transistor

texts:
How it's possible to turn on/off a single LED with the left (or right) sound channel of an audio jack and a pnp transistor.

Everywhere npn transistors are used. Like here:

Driving LEDs from audio signal
LED Color Organ Triple Deluxe

I'm very new to this topic and need the led control for a simple project of my computer science master thesis. My uncle gave me some old pnp transistors and I built something like this:  and this: .

When I use my fingers the LED glow. But when I connect my audo jack and play a song, nothings happens or the LED glows very very (not visible) low. I thought, that the 5V will give the power although the audio jack has not enough power.

Are npn transitor needed or is there a very simple way to use pnp transistor to let the LED glow, when a smarthone plays a sound throuh the audio jack? A simple circuit diagram would be helpful.

(image source: http://www.talkingelectronics.com/projects/TheTransistorAmplifier/TheTransistorAmplifier-P1.html)


texts: Need help identifying capacitor values from monitor PCB

texts:
I am trying to replace the SMD electrolytic capacitors from an LG E2442 but I am getting confused in regards to determining the correct values. I am trying to determine three different cspacitors types as shown in the images below.
I can somewhat determine some of the values of the first one but get really confused about the others.

For the first Capacitor I believe:
100v = 100 Volts
27 = Capacitance but I am unsure what the symbol before and after it is therefore I don't know how that is modifying/multiplying the value
J = 5% Tolerance
33 = ???

Here is an image of the PCB with the capacitors in red circle in case it helps.

Any help would be greatly appreciated.


texts:
I saw this application example in the LM324 datasheet.

In a case like this:

where R1/R2 is equal to R4/R3 and R4/R3 is large (330 like above), the first op-amp seems to act like a unity gain buffer; its output isn't much different from its non-inverting input.

Also, the inputs (and thus, the output) to the op-amp are already offset by Vcc/2 and buffered. Is there still any need for op-amp U1A above? Can both inputs just be fed into U2A directly without compromising the "High Input Z" quality (or anything else) of the original circuit? I'd also like to understand what is meant by "CMRR depends on this resistor ratio match" in the first image.


texts: I'm making a battery out of two 3.75V Li-Ion cells to go into a speaker system that powers an amplifier. I was wondering on the PCM, how many volts would be max to charge these cells? The cells I have are from an old laptop battery and the batteries still work fine. I need a way to charge the batteries without removing them from their casing and still power the amp and everything always in closed. I'm sorry if I'm unclear at all.


texts:
As you know, the MAX1555 is a popular single cell lithium polymer charger. It can take USB power directly, restricting the charge current to 100mA or so.

Are there any other MAX1555 alternatives that are your favourites? I'm just browsing around for alternatives at the moment, seeing if they offer some other features.


texts: The transfer function for a 2nd order opamp low pass filter

texts: trying to find the transfer function for a 2nd order opamp low pass filter, can i get a help to find my transfer function ?


texts: How to safely create an AC short circuit?

texts:
The company I work for builds products that typically have integrated fuses or circuit breakers. During our product validation testing, we would like to begin integrating a test which will basically be an AC short circuit, in order to get an idea of the effect of the short on our product (for example, how many milliseconds will it take for our circuit breakers or fuses to react to the short circuit). How can I safely create a Line to Neutral short of a live AC circuit?

(The lab that we will be testing in is fully isolated electrically from the rest of the building, and has all of the circuit protection that we will need. The lab is built like a bunker and anyone near the testing will be wearing the appropriate PPE. We know that this testing will be dangerous, and we have all of the safety aspects covered.)


texts: The Thermal relief consideration for TVS diode (for ESD protection)

texts:
I am designing a print which has some mircofit connectors, I have placed TVS very close to the connectors on the print and the ground pad connected with a GND polygon directly, this polyon connects with a ground layer by GND vias.

My question is, since the ground pad of the TVS diode connects to the a copper plane directly, do I need to use thermal relief connection between the GND pad and the copper plane like below?

I knew that TVS diode is used to shunt the ESD current, so i am expecting when ESD happen, there is a huge current goes through the TVS diode for a very short time, according to IEC 61000-4-2, almost 30A current in 800ps (90/10 rise time), if a thermal relief is needed, how do I use these information to calculate the trace width and air gap for the thermal relief connection?

My last question is if the other pad of the TVS diode, which connects with the ESD source can be soldered easily(also shown in the pciture), do I still need to care about the GND pad?

Thank you very much!


texts:
I'm looking at the Sparkfun USB-C PD Board schematic and noticed this portion under ESD protection as seen below.

It looks like two Zener diodes facing each other thus prevent current flow in either direction. I looked at the properties and it said TVS diode. But with some lookup on the TVS diode, it didn't give me it's importance in the role here.

Can someone explain what this diode exactly is with this symbol and what its role is in the overall function.


texts: I don't understand why it is necessary to use a trigger on an oscilloscope for data acquisition

texts: I just can't understand why this is completely necessary. Take a sine wave for example. It's repeating. Can't the oscilloscope really "choose" anywhere to start the data acquisition. Since it repeats you'll get the same thing, right?


texts: Broken stepper motor - Too high of a load?

texts:
I am using a NEMA 17 (17HD4005-22B) with a Big Easy Driver and an Arduino Uno R3. I am using the motor to move a threaded rod, which then pumps a liquid. The system basically functions as a linear actuator.

After trying to move a much too high load, I noticed that the stepper motor was not turning correctly. It moved erraticaly forwards and backwards a couple of steps. I also noticed to following:

When I give it the signal to turn, I can turn the shaft very easily with my hand in either direction
When it is powered and without any signal to turn, I can turn the shaft easily with my hand in either direction most of the time. If I crank the potentiometer all the way, I can not move it anymore
I connected the motor to the stepper drivers of an i3-clone printer, and  the motor does not turn. The previous two observations remained
I connected the Big Easy Driver and Arduino to one the motors of the 3D-Printer and the 3d-printer motor did not turn
Both windings of the broken motor have the same resistance

My doubts:

Is it possible that the high load caused the stepper to break?
Is it possible the driver is also broken?
How can I check any these possibilities?


texts: What is the simplest design to replicate Oerstead's experiment at home?

texts:
I want to demonstrate what Oerstead did several centuries ago. He demonstrated that there is magnetic field near a current carrying wire.

I have a compass that is sensitive to earth magnetic field of about 25-65 micro tesla. I attempted to replicate the experiment with a wire and an  accumulator of 12 volt, 7 Ah. Even though I short circuited the accumulator for about several milliseconds, the produced current is not enough to generate magnetic field that can deflect the compass needle.

$$
B=\frac{\mu_0 i}{2 \pi r}
$$

For r=0.05 m I need about 16.25 ampere to produce 65 micro tesla.

Question

What is the simplest design to create a DC power supply that can produce about 16.25 ampere or more?


texts: What are the names of these 2 connectors?

texts:
These two types of connectors I do not know the name and I would like to.

1.

2.


texts:
I already know what a MPPT is supposed to do. It's basically a buck/boost converter connected to a solar panel that finds the ideal power output by changing (boosting or lowering) the voltage of the panel. That's all well and good, however, this is where I get confused.
Once you connect the load to the MPPT, let's say our solar panel voltage gets boosted to 50V, and we then want to charge a car battery with it, which is currently at 12V.
Once we connect the MPPT to the battery, the voltage will drop to the battery's 12V...so...why did we boost the voltage in the first place? Is there now more current available now that we're using MPPT since there's more power? Is it the same as just connecting the solar panel directly to the battery?


texts:
I am trying to calculate how long that a trail camera can be deployed before the batteries run out. The trail camera in question is a Reconyx HyperFire 2.

Here is a useful review of the trail camera that gives a unit of power consumption in Watt seconds.

The trail camera contains 12 AA batteries of either a NiMH or Lithium configuration. We're more interested in the Lithium configuration since the batteries hold up significantly better in cold temperatures.

Here are the quoted power usage figures from the review which I am hoping are correct:

Standby Power: 0.65 milliWatts
Picture Day Usage: 1.2 Watt-seconds
Picture Night Usage: 6.5 Watt-seconds

35 * 1.2Ws = 42 Watt seconds for 35 Daytime Photos per day
35 * 6.5Ws = 227.5 Watt seconds for 35 Nighttime Photos per night
0.65mW standby * 24 hours = 15.6 milliWatt-hours per day or 0.0156 Watt-hours per day

Technically, it should be 23.98 hours but the difference is not significant enough to consider.

Moving on, 3600 Watt seconds make up a Watt Hour
Watt hours are the result of Voltage * Amp Hours
Therefore, Watt Hour / Voltage = Amp Hours

We're interested in finding amps used.

227.5 + 42 = 270 Watt Seconds total for day/night
270 Watt Seconds / 3600 = 0.075 Watt Hours
0.075 Watt-hours + 0.0156 Watt-hours = 0.0906 Watt-hours used total

There are two scenarios based on how the trail camera is setup internally.
In the event that the trail cameras operate on 12 Volts DC (12 AA batteries in series):
    0.0906 / 12 = 0.00755 Ampere-hours

Or in the event that they run on 6 Volts DC (two sets of six AA batteries in wired in parallel):

0.0906 / 6 = 0.0151 Ampere-hours

If the power usage during day and night photography is the same as its given in Watt seconds, then both of these numbers will be equivalent regardless of battery storage capacity.

12 Volt Scenario:

3,000mAh or 3Ah
3 / 0.00755 = 397 days (35 day, 35 night shots per day)

6 Volt Scenario:

6,000mAh or 6Ah
6 / 0.0151 = 397 days (35 day, 35 night shots per day)

Okay, that makes sense. The quoted figure for the trail camera run time for day/night photography is 16.6 months.

This is where the review loses me.

397 days / 30 = 13.23 months

However, if we don't factor in standby power usage, it's 480 days.

480 / 30 = 16 months.
0.075 (35 day/night photo power usage only in Watt Hours) / 12 Volts = 0.00625 Amperes

3,000mAh or 3Ah
3 / 0.00625 = 480 days. 480 / 30 = 16 months

Please correct me if I have any of this wrong. Obviously there are many variables that effect battery performance, including the electronic components. All I am looking for is a rough estimate based on the available data for deployment in colder temperatures.

I found an article that shows a temperature vs discharge curve for the Energizer Ultimate Lithium battery here.

If that is to be believed, then the trail camera uses 6.25mA to as much as 12.5mA which means that the effects of colder temperatures on the Energizer Ultimate Lithium batteries should be negligible. The trail camera is drawing less than 25mA which based on the battery discharge curve means that the battery capacity should remain the same.

0.00625 Amperes = 6.25mA
0.0125 Amperes = 12.5mA

Please double check my calculation or shout WRONG WRONG WRONG while banging a pot or pan with a wooden ladle. Either works.


texts:
So I am starting to make my first RF circuit board.  We will be using a PSoC4 BLE chip as the transceiver. I'm doing my best to follow their application notes, specifically this one.
I should add an RF test point so that I can tune the matching network once the assembly prototypes are built.  However, I'm confused on where I should place it.  Most of the references I've seen have said that you need two matching networks on either end of your 50-Ohm transmission line - one near the transceiver, and the other near the antenna.  The test point should then go in between the two, on the 50 Ohm line.
However, in both the cypress BLE kit and the Cypress BLE USB Dongle, only a single matching network is used.  So where does the test point go?

I followed the app note suggested practice for using their MIFA antenna design, and I will feed the antenna with a 50-Ohm microstrip.  But I'm unsure about what happens on the other end of that that 50-Ohm line.  Does it terminate at C14 (referencing the above schematic), or do I continue another 50-Ohm impedance line all the way to the RF pin on the transceiver?  Do I place the matching network near the antenna, near the RF pin, or near the middle?


texts: Can I connect multiple devices via a single I2S interface?

texts:
The host processor I'm planning to use has only two I2S interfaces, however I need to connect 6 devices to it. Is it possible? If so, how?

Thanks.

Update.

Sorry, folks, I indeed should have provided more information. The devices in question are microphones - which normally have I2S and/or PDM interfaces. For the sake of this discussion, lets say ICS-43432 (https://invensense.tdk.com/wp-content/uploads/2015/02/ICS-43432_DS.pdf) which needs to be connected to say QCOM CSR8675.

The problem is that CSR8675 has only two I2S interfaces, but I need to connect four mics.

Thanks for the patience!


texts: How to use the enable Pin and Error Flag Pin of MIC29301 12V regulator with an Arduino

texts:
I am completely new to electronics and I am looking to implement a simple 12V Vacuum Pump power and control circuit with an Arduino.
I chose the MIC29301 as the 12Vout regulator to be directly connected with a 12V lifePo 4 battery. The diagram is attached below:

The GND, IN, and Out were pretty straightforward. However, I am trying to be careful with the Enable and Flag pins as I don't know a lot about them.
My question is how do I connect the enable pins with an Arduino to use it as an on/off logic switch (i.e if resistors are required or it can be connected directly)
My other question is about the Error Flag pin which I am completely new to. I am trying to use this pin to read for drop in output voltage from the regulator, but I am completely lost on how to use this pin or connect it with the Arduino. Please I would love some guidance and explanations on how and why some of the recommendations will work. Thank you.


texts: What does the acronym LCA mean in relation to battery cranking amps?

texts:
I am attempting to compare some lithium iron phosphate batteries to their standard lead-acid counterparts.  One metric used is the CCA (cold cranking amps) value.  However, these lithium batteries use an acronym "LCA" instead... for example "480 LCA" which is an unknown term to me.  I assume CA = Cranking Amps but I can't figure out the "L".

I'm unfamiliar with the term LCA and can't seem to find it on google, except to mean "Lifecycle Analysis" which is not applicable in this case.

Can anyone tell me what this term means, and how it compares to CCA of standard lead-acid batteries?


texts:
I am solving the operating point of this circuit to find \$V_{OUT}\$ and \$I_{C}\$, assuming ideal opamp and BJT.

Due to the opamp the node \$B\$ is a virtual ground so \$V_{OUT}\$ is from the voltage divider \$R_2\$ and \$R_3\$ and with \$V_{DD} = 10V\$, \$V_{OUT} \approx 9.95V\$.
Now how can I get the \$I_{C}\$, given \$\beta_F = 200\$? Is the BJT in saturation mode?

I have also tried simulating the circuit in LTSpice but I get strange results: using real component (LT1001 and 2N2222) \$V_{OUT}\approx -9.95V\$, with ideal components \$V_{OUT}\approx -0.002V\$.

simulate this circuit – Schematic created using CircuitLab


texts:
I am a programmer and I need to send data to the machine, but I have to add checksum at the end of the data.  Can someone show me an example how to do it so I could then write an program to calculate the checksum for me.

The rules:
Bitwise inversion of the 1 byte sum of bytes beginning with the
most significant address byte and ending with the byte preceding
the checksum. (To perform a bitwise inversion, "exclusive OR"
the one byte sum with FF hex.)

Thanks


texts:
I am new to PCB design. I am creating a 4 layer PCB with the following layer stack:

  Signal (1) - GND (2) - Vcc (3) - Signal (4)

Now, I'll need Vcc and GND on both the signal planes. This means I'll need blind vias from 1-2, 1-3, 2-4, 3-4 but the PCB manufacturer I chose said that they cannot do blind vias like that - it has to be 1-2, 3-4 and such. Now I am stuck and have no idea how I shall route Vcc and GND. Please help.


texts: Multiple CC/CV charge controllers in parallel?

texts:
Is it possible to put multiple cc/cv charge controllers (TS1052 for example, which is rated for 100mA drain current) in parallel configuration to achieve a higher drain current? (input signals also connected in parallel) Or would this configuration create issues? (taking the TS1052 as an example, would putting ten of them in parallel result in ten times the max drain current? So 1000mA instead of 100mA in this example?)
Here is the datasheet for the TSM1052: https://eu.mouser.com/datasheet/2/389/cd00152575-1796500.pdf
Thank you very much? :)


texts: how determine the RC time constant in PWM digital to analog low-pass filter?

texts: I 'm looking for the best RC time constant and its reason in a PWM to convert digital signal to analog based on duty-cycle and frequency and other parameters. PWM frequency is 10 kHz.


texts: Loaded Q-factor of parallel RLC with series resistive load

texts:
So I have been studying resonant RLC-circuits, and have come to loaded Q-factors. At present I am trying to figure out the Q-factor of a circuit like this:

simulate this circuit – Schematic created using CircuitLab

My textbook (or lecture notes, rather) claims that the Q-factor of the above circuit will be \$Q_L =\omega_0 C (R // R_{load})\$, i.e. the same as if the load resistor was connected in parallel with the resonator. The only online resource I've found seems to agree (see page 5).

When I try to calculate the Q-factor I instead get

$$Q_L=2 \pi \frac{\mbox{Max energy stored}}{\mbox{Energy lost per cycle}} = 2 \pi \frac{v_2^2 C/2}{(v_1/\sqrt{2})^2/((R+R_{load})f_0)} = \omega_0 C (R_{load} + R) \left(\frac{R}{R+R_{load}}\right)^2=\omega_0 C \frac{R^2}{R+R_{load}}$$

since \$v_2 = \frac{R}{R+R_{load}}v_1\$ at resonance. Have I misunderstood the Q-factor, or messed up my reasoning somewhere?


texts: Are electromechanical oscillators still in use? Or totally obsolete?

texts: An electromechanical oscillator is basically an AC generator that has a much wider frequency range. I read something on a wikipedia article about a radio frequency AC generator used for military radio transmission around the turn of the 20th century. The interest comes from developing an oscillator that has very low frequency(10 to 30 Hz)and could produce an output power of at least 100kW and even into the megawatts. It would be essentially a low frequency AC generator.


texts: Does this PWM driver require additional protection to the MOSFETs?

texts:
I have designed a circuit to run a 555 as an astable multivibrator. The values for the oscillator are a 4.7 uF capacitor, a 1k resistor, and a 10k potentiometer. For the capacitor I will use an electrolytic cap, so the value is not exact. This should give an oscillation frequency of no more than 500 Hz maximum, with a duty cycle between 50% and 99%.

The intent of this is to use it to control N-channel MOSFETs for PWM-ing brushed motors. The motors are vacuum cleaner motors, up to 12 amps each. The MOSFETs I have are IRFP460A. I'll need to use rectified mains to do this. This circuit should be testable with a lower voltage, although I'll need to use a dummy load.

The circuit also includes a bridge rectifier constructed from 1N4007s and a 7812 regulator. This will be driven from a small transformer with an output voltage of 20 VAC. This gives a voltage to run the 555, as well as control the gates of the MOSFETs. Since the 555 is operating from +12 VDC, there should be no need for a level shifter. The 555 is not directly operating the gates, I have a 2N3904 that is used to amplify the output of the 555.

Each MOSFET has a 1000 ohm pull down resistor between its gate and source. The gate is driven via a 10 ohm resistor. This means that turn on should be relatively fast but turn off is not as rapid. I don't think this is an issue below 500 Hz. If I have a 99% duty cycle at 500 Hz, the 555 should still be off for 20 microseconds.

Here is my schematic and the circuit board I've designed

There are a number of additional headers on this board, I may use them in the future to take +VDC power from the board.

Here is a quick listing of the parts

D1-D4 - 1n4007
LED1 - A Red LED
R1, R12, R5, R6, R7, R10 - 1000 ohm resistors
R3 - 3.3k ohm, used to drive the base of Q1
Q1 - 2n3904
C1 - Any electrolytic cap I can find to filter the DC from the rectifier
C4 - 10 pF
C5 - 4.7 uF
R2 - 10k potentiometer
All four MOSFETs are IRFP460
C1, C2 - 0.1 uF capacitors
C6 - unsure as to the value

Here are my questions with this circuit:

I moved all the MOSFETs down on the board. Does this help or make the problem of EMF from gate charging? C6 is located down near the MOSFETS, can I size it appropriately to filter out any transients from the gates charging?
Is there anything I can add to protect the MOSFETs from voltage spikes from brushed motors? Is this even necessary?


texts:
I am trying to measure the resistance of a AA alkaline battery. The circuit I am using is shown in a photo below. I have also attached the values I obtained.

Somehow, the values I am getting fluctuate quite a bit and seem to be an order of magnitude larger than that specified in the datasheet (https://data.energizer.com/pdfs/e91.pdf). 1.0-3.3 ohm compared with 150-300 milliohm.

Please could someone show me where I’ve gone wrong with the calculations. Should I be using a different circuit? Is my battery model inadequate? As far as I understand it, battery’s internal resistance should be roughly constant for a certain state of charge and all the values I obtained occurred roughly at the same state of charge (I used a fresh battery and the battery ran for less than a second for my five tests).


texts: LM317T outputs current on Adjust pin with nothing connected between adjust and Vout?

texts:
I have a LM317T-based simple circuit and I'm using a 12V battery to power it. I connected the Vin to + 12V and made a constant current circuit as shown here. Now, I'm using a variable resistor of 100k instead of a fixed-value resistor and have connected a LED in place of RL of the diagram.

Now before connecting the + 12V to Vin, I set the resistor value to the maximum, 100k ohms. This is a really large value so the current flow to the LED should be so low that it shouldn't light at all.
But the LED lights up very dimly.
And if I reduce resistance on the variable resistor, the LED becomes brighter as current flow increases, as expected.

Even if I remove the 100k resistor and keep the path between Vout and Adjust open, the LED still lights up very dim.
Is this normal? Why is this happening? Can anyone explain this behavior of LM317T?


texts:
I have 3 kOhms resistors, one voltage (5 V), 2 switches so I can control my input.
Can someone help me?
I need to do like this:

I have done this so far:


texts: Whats the difference between a circuit with a capacitor under DC and a RC circuit under DC?

texts:
Does the process of "charging" and "discharging" occur in the same way but with more resistance ?
Im not too sure on what the difference is between the two and whether they behave differently.


texts: Measuring an AC-voltage at the ouput of a full bridge rectifier

texts:
I've a full bridge rectifier and I put the following function into it:

$$5\sin(100\pi t)\tag1$$

So, at the output I get:

$$\left|(5-2V_d)\sin(100\pi t)\right|\tag2$$

Where \$V_d\$ is the voltage over one diode.

Now, why do I measure (with a Fluke multimeter) a DC-voltage of \$1.4\$ volts and an AC-voltage of \$0.5\$ volts. Why do I measure an AC-voltage, is it not completely DC?


texts: Capacitor and resistor in parallel in output 19V laptop charger

texts:
I have been studying with my charger and I cannot figure out why it leak ac while also providing DC 19V. When I touch anode and cathod of the charger and checked it, there were no ac current flow. I want to reduce the current or make it safe to work. How can I do this ? Also giving capacitor of 25V and resistor in parallel does the job. But will it cause any problem in future ?
Thank you..


texts:
Is there a trick to implementing the current source in the setup below, for 20uA ballpark (besides switching or steering a pair of individual source/sink)?

This is in a single supply roughly 5V system (3.3V would be nice as a bonus). One of the objectives is to reduce dependence on Vcc.
Other details: signal is 0.1-1kHz. Accuracy goal is 10% over parts and temperature (10-50C machine compartment).
The input to the bridge is rougly R2R, the voltage at the output end is roughly mid supply, so current should flow in both hi/low states.
LM334 was about the only thing I found, and it seems a bit dated and temperature sensitive.
Maybe something clever with an op amp and a voltage reference?


texts: What is purpose of components in this circuit

texts:
I'm trying to understand this circuit but I can't understand purpose of R4 and R6.
Can someone explain their purpose?


texts:
Can anyone explain in detail how the true single phase clock below works?   I need to understand it well so I can design it with CMOS technology and know how to size W/L for each MOS transistor.

Link: here, at section Edge-triggered dynamic D storage element.


texts: How does the maximum transmission rate depend on the carrier frequency?

texts:
This question refers to the following excerpt from Computer Networks by Andrew Tanenbaum:

  The amount of information that an electromagnetic wave can carry is related to its bandwidth. With current technology, it is possible to encode a few bits per Hertz at low frequencies, but often as many as 8 at high frequencies, so a coaxial cable with a 750 MHz bandwidth can carry several gigabits/sec. From Fig. 2-11 it should now be obvious why networking people like fiber optics so much.

Fig. 2-11 basically just shows the electromagnetic spectrum with "Fiber optics" spanning from \$10^{14}\$ to \$10^{15}\$ Hz, i.e. at substantially higher frequencies than other media (like twisted pair, coax or FM radio).

I understand that a signal's bandwidth corresponds to the "speed" at which it can be modulated, thereby influencing the amount of information that it can transmit. But why does the absolute value of the carrier frequency matter in this case? Why, for example, is a frequency band of 1 kHz more "valuable" if it is located around 100 MHz rather than around 500 Hz (i.e. the baseband)? Wouldn't this also mean that, for example, using a blue instead of a red laser as optical transmitter results in an increased transmission rate?


texts:
So in my project I need to have 3 outputs that has 5v ( with each at least 1,5A)  and one output that has 9v, so I though what if I bring one 9v source voltage with like 5A and put 3 regulators 7805 so I will have a circuits like this :

Note that the regulators are not in parallel as each will supply a part in my project, so I wonder if I may have any problem using this circuit? if so how can I solve my poblem.


texts: How important is the number of cores in RJ45 jacks with magnetics

texts:
While searching for RJ45 jacks with magnetics (MagJacks) in Digikey, we found that there is a selection criteria which says "Number of cores per jack". Though we have been using MagJacks previously, this is the first time I noticed that criteria. I compared the datasheets of few jacks with 1 core and 2 cores per jack, but couldn't find any notable difference.

Is there any significance to this parameter?
Which type of connector is better - the one with lesser number of cores or the one with more cores?
For the same application, if I use a jack with more number of cores, what is the advantage which I can obtain?


texts: Trouble to find out the nominal motor current and motor type of a fan from its datasheet

texts: Is there a way to find out what is the nominal current of this fan and what type of single phase induction motor is used?


texts: Question about clearance/pad diameter and PCB design

texts:
Sorry if this is a silly question but I am relatively new to Eagle and I am 100% new in dealing with high powered PCB design.

So, I am making the footprint for the LEM LV 25-P voltage transducer seen below.

+/-HT will be +/-500V, and the clearance specified in the datasheet is 19.5mm.

However, the primary pins and secondary are exactly 19.5mm apart.  In this case, how can I have a pad of any size at all without putting the part at risk?  Is there something about the pad layer I'm not understanding that will insulate it from this hazard?  Again, I'm sorry I'm quite new to this.

Not sure if this will be helpful, but here's the footprint so far as well.


texts:
I have purchased 16 Red 3-5V 650nm 5mW laser modules which I believe have a driver included.  I also have a 100000mAh Li-Polymer battery with 2 USB outputs, one at 5v 1A and one at 5v 2A.
If I wire the laser modules in parallel, should this work as the voltage would be 5v across them all?  If so, how many laser modules in parallel could the battery support?  Do I need anything else in the circuit?

Link for the laser modules is http://www.ebay.com.au/itm/Industrial-linear-Red-Line-3-5V-650nm-5mW-Module-Focusable-Adjustable-Laser-Head/191968924976?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649


texts: What is the possible reasons that cause the different motor strokes of two directions

texts:
The question may be a little too specific since it refers to some special choice of the motor parts that may not be used for everyone, yet I would like to learn about the general debug methods if similar problems occur.

I used a motor driver QJ-215 or CW-215 to control the moving of a linear stage PSL-85. My Labview program sends out the trigger pulses to the motor driver in order to control the direction and step size of linear stage. The pulse sequences for both directions are the same, so the linear stage is supposed to achieve a raster scanning with the moving distance same at both directions (+x and -x). The whole system works well.

Now I have an exactly same motor control circuit as the worked one. However, there is a problem with the new motor control part: the distance that the stage moves along +x axis seems more than the one it moves back (-x axis). As a result, the linear stages moves far away the original starting points as the scanning proceeds.

I can exclude the software glitch because: (1) it all worked well on my previous motor control circuits; (2) the pulse of direction is always provided prior to the pulses of moving steps in both direction, so there may not be pulse missing.

I also excluded the possibility of QJ-215 damage (H-bridge circuits broken, transistor not enough gain, etc.) since I have already changed another QJ-215 but same problem existed.

So there may be something wrong in the circuit connections onto the motor driver QJ-215. As you can see, the motor driver is not complicated designed with only a magnetic coil (A+,A-,B+,B-), and the H-bridge circuits with a bi-switch (DIR) and a step pulse receiver (CP)). I would like to know what kinds of errors in the circuits connections may cause such a unequal moving distance along +x and -x direction of the linear stage?


texts:
Following the diagram below, is it wrong to use the MCU 5V to supplying both SDA and SCL lines?
I applied this into my circuit and my device are not communicating when connected to this circuit.


texts:
I want to be able to determine the location of an object that will be moving around in a rectangle about 15" X 10"

The location must be accurate to within about 1/4" and be measured at least 100 times per second.

The first idea I had for accomplishing this is to have the object transmit a pulse signal every 10ms and have a receiver in each corner wired to a micro controller and measure the difference in time between when each receiver gets the signal to triangulate it's source.

My first thought was to use IR receivers and transmitters, but I would have no idea how to do the triangulation with signals that move so fast.

So then my second thought was to use sound. I would want to transmit at a frequency above the human hearing range. And it seems to me that higher hertz = greater accuracy. The speed of sound is about 13,400 inches per second. So that means to get 1/4" resolution, I would need 56kHz or higher.

First off, I've never dealt with sounds above the human hearing range. This will probably be on for periods of about an hour, and may be just a few feet away from ears. As long as I use low power, is there any way that this could be a hazard?

Secondly, what kind of speakers are capable of transmitting 56kHz? And similarly, what kind of microphones could pick up 56kHz?

Other methods of triangulation would also be appreciated.


texts: Just a quick question. is this a correct circuit? would it drive 500mA device? given using AMS1117 as the regulator? Do we need to add heatsink? any alternative to step down the 12V to 3.3V without using heatsink?


texts: in this model can anyone explain me how is it going to work in CV mode and where is the potential divider and all, like where is the Vfb


texts: Manual Demonstration Circuit for 74HC595 Shift Register

texts:
I am trying to create a manual demonstration circuit for a 74HC595 shift register. Se my circuit below. The problem I am having is that I am only getting a +0.7V signal to the data, clock, and latch pins of the 74HC595 when one of the buttons are pushed. The S4 RESET switch works fine (normally high at 5V, press switch to bring down to 0V), however S1, S2, and S3 do not accomplish the reverse scenario (normally LOW, press switch for HIGH) correctly.  You will note that I am also trying to debounce the switching with a capacity or resistor. I suspect this debouncing set up is creating my problem.

Does anybody have any advice on how to create a debounced normally LOW, momentarily HIGH switch that switches between 0V and 5V?


texts: What, if anything, makes shielded loop antennas so great at rejecting local noise?

texts:
There is a folk wisdom, among amateur radio operators, that if you have a lot of noise on HF, such as in an urban location, then using a shielded magnetic loop antenna for receiving is really great for rejecting that noise. Here's an example of such an antenna:

(full description)

There are many variations on this theme, but the common points seem to be:

A small loop
Some sort of shielding around that loop (often constructed from coax)
(usually) a break in the shielding opposite the feedpoint

Is the idea here to make an antenna that picks up the B-field, but not the E-field, on the theory that the antenna is in the near-field of predominately electrostatic noise sources, like arcing motor brushes? Is this antenna any different than a B-field probe? Are there other B-field probe designs that would be more effective as a receiving antenna designed to reject local noise?

Further, what makes the shielded loop antenna more special? I can't find much information on it that isn't anecdotal. Is there some mechanism that justifies this extra complexity, or is it just folklore?


texts:
I have the following frequency response:
$$H(e^{jkw_0}) = \begin{cases}0, & -4\leq k \leq-3\\ 1, &-2 \leq k \leq 2\\ 0, & 3\leq k \leq 4\end{cases}$$

And I have graphed \$h[n]4\$ as the following:

and \$h[n-4]\$ as the following:

I would like to argue that \$H_c (e^{jw}) = e^{-4jw}H(e^{jw}) \$ have the same magnitude about a strong phase shift. Would it be sufficient to say that the have the same magnitude based on "inspection?" And, for the phase shift, I can once again clearly see that it has time shifted by \$ 4 \$. However I am not sure how would I prove that the phase shift is \$ 4w\$.


texts: How to increase and maintain voltage gain of DC DC converter with switching load, and choose the right capacitor and indcutor

texts:
I have a boost converter that with load 22K, it produces 120V with input 12V. the inductor is 220uH and the capacitor is 150uF. i need it for ultrasonic pulser with frequency of 1-10 MHz, the load of the pulser is 2.2 Kohm. i use arduino as switching controller of the mosfet in boost converter. the arduino will get the output voltage and adjust PWM (31 KHz) with PI system to calculate duty cycle. the problem is, when the output voltage is not attached to the pulser load, it gives exact 120V, but attached, it drops down to 70V, to maintain the output 120V, the input need to be increased to 24V, but i want it to be 12V, what i have done are

make the KP and KI of PI higher, not work
increase the inductor value, not work

how can i maintain the output? as far as i know, that the gain need to be higher, but how?

the second question is, how to calculate the value of capacitor and inductor? for the capacitor rating, is it necessary to match the capacitor rating with output voltage or the input voltage?

could i use a cascade boost converter? for an example using XL6009 to boost my 12V to 28V and then feed it to the boost converter?

this is my schematic


texts: Wireless earbuds 18650 battery high pitch noise

texts:
I've decided to replace 18650 in my T9 TWS earbuds charging case. Went with Sony. Case initiates with all segments on the LCD lit up. All good so far. Once I put the earbuds in, I can hear "modem like" low volume high pitch noise. LCD shows some bogus battery charge level (very low). LCD shows charging for few seconds and turns off.

Battery is for sure charged and healthy. The same now happens with the original battery (which I've charged outside of the case).

Can it be voltage to high for cheap built-in charging circuit?

Here is the detail:

Gray cable in the middle leads to the LCD. On the left there is MicroUSB in, on the right USB out (case can act as a battery pack).


texts: Adding bulky capacitor vs multiple parallel capacitors on Boost converter's output

texts:
For VOUT, I noticed you can add capacitors in parallel to handle voltage ripples.

If all capacitors are populated, it will be

10+10+10+100 = 130 uF

I wish to compare

populating all 4 capacitors (20% tolerance, 35V rating) VS
populating a single capacitor, like 150uF EEE-FTV151XAP (20% tolerance, 35V rating)

Is there a big difference between these two?


texts:
What is the best way to limit an audio signal for ADC input (to 0V - 3.3V) with out disrupting it harmonically?  Ideally, I'd like the conditioned signal entering the ADC to be a signal uniformly spanning 0V to 3.3V. That is, I'd like to strip the original signal of its envelope and have a flat envelope at the output. I've spent the better part of a month attempting to get simulations of different VCA circuits to respond to these specifications using variations on the original input signal's envelope as the control signal. I know near-blind trial and error through simulation is not the most elegant way to go about design but I'm early in my EE studies and it's all I have.

Is there a standard scheme for this kind of signal conditioning?

Is designing a circuit, whose response is consistent across the audio band (or a good part of it), which attenuates/amplifies a signal, varying from 0.1Vpp to 6Vpp, to a uniform 3.3Vpp signal with negligible change to the harmonic content (negligible meaning that an FFT would still faithfully report the first several harmonics of the original signal) a realistic goal?


texts:
I am modifying a system that is powered by the ignition circuit on a vehicle. Currently there is a simple physical on/off power switch. However, I am introducing a touch-screen computer that must have the opportunity to shut down gracefully when power is lost (e.g ignition circuit is switched off).

How would I go about designing a system that behaves as follows:

When the ignition circuit is turned on, the system boots (i.e. it is powered up)
When the ignition circuit is turned off, the system switches to a backup battery, and sends a signal to the computer to shut down
After a fixed duration, power is cut regardless of whether the computer shut down cleanly
When the ignition circuit is on, the backup battery is charged

Are there off-the-shelf components that would help in this design?

Will I require a small microcontroller to build a custom solution?

I have come across LTC4415 in prioritized power supply ORing.


texts:
I need to make a power switch (on the very cheap) for an electric vehicle.

The battery bank is a 8s (29.6 Vnom) LiPo pack, powering an ESC which drives the motors.

Max continuous current to be drawn through the switch is approx 120 A. Peaks can be expected at about 180 A or so, but very infrequent/hardly at all.

The constraints are that the circuit must be powered from the battery pack, and not draw much/any current when in the off state. There are also some dimensional constraints (ie that the entire solution shouldn't be bigger than like 50mm x 50mm x 20mm or so).

I would imagine that I would need a mechanically actuated switch at the rated voltage, that enables a contacter of some sort (mechanical/electrical/solid state).

I've been doing some research, but I need a little advice as to what I should go with for a super cheap solution.

So far I've come across:

Thyristor circuits

MOSFET switching circuits

Solid state relays

Mechanical relays

Some of these might require a DC/DC converter or something to get the voltage down to useful levels to engage the switching circuitry.

Does anyone have any other ideas and could someone suggest what the best (cheapest) option would be to go for here?

Thanks


texts: Searching for the right temperature sensor with 0.001

texts:
Is it possible for me to build a temperature sensor with 1mK accuracy?

First I think I need to find the right temperature sensor. My problem right now is I can't find a temperature sensor with that accuracy.

Thanks for the help.

Edit 1: As I can read from the comments finding the right sensor might not be a problem but the calibration will be a problem. I will discuss with my supervisor whether he can reduce the accuracy requirements or not. Thanks for your responses.

Edit 2: The application of the sensor is for measuring the accurate freezing point of milk to be use in a milk quality tester.


texts: Optimal filter for different resolution measurements

texts:
I will try to be brief and simple. (that are not my cualities)

Introduction :

I have to plot a signal that at the beginning has a big value, let say 60V and then the signal stays near 4V.

The signal is measured by 2 “12bits-ADC” (0V to 3V):

The first channel has a gain of 3V/60V = 0.05V/V (So it could measure the entire range)

The second channel has à gain of 3/10V = 0.3V/V and saturates the signal at 3 volts to avoid to damage the ADC.

I did that because my resolution is very poor in the 4V zone if I use the entire range to measure the signal and I need the BW, so I can use filtering to increase the number of bits. There is also another reason, the system has a lot of noise, so the SNR with a gain of 0.05V is ok for signals over 10V but it is not enough for signal under 10V.

Question:

There is an optimal filter/algorithm to use the 2 measurement with different resolutions to build the signal/plot? I would like to avoid transitions distortion near the 10V region.

Thank you very much.


texts:
I'm trying to measure the relative signal strength received by a dipole antenna for orientation purposes. I'd like to do so using an ordinary multi-meter.

I don't know much about RF circuits, but this is the circuit I came up with.

I was planning on measuring the resistance across the banana connectors to represent the relative inverse of signal strength.

Would this work? If so, which diodes and transistor should I use? If not, which circuit is best?


texts: Solar cell charging and battery chemistry for low power 2.4-3V supply?

texts:
I've recently been looking into the possibility of using an amorphous silicon solar cell (like they have in calculators) to supplement my very low power BLE system's current consumption to extend the life.

I've found some cells that can provide 10-20uA of current during daytime (indoors). Since my system is mostly in a low power state, this power supplement is enough to offset some of the total power consumption and greatly extend the battery life.

The voltage supply required for my system can be anywhere between 2.4v and 3v, but probably needs a battery capacity of >750mAh to keep it alive for as long as it needs to be. What would be the best battery chemistry to use in this scenario? And what is the most efficient way to charge the battery(s) while keeping cost to a minimum?

(I've found a solar cell supplier that does a variety of voltages, so that shouldn't be an issue)


texts:
I need to find the output impedance of the BJT amplifier as shown below:

The equivalent small-signal circuit looks like the following:

I know that the output impedance is $$Z_o=R_{E1}\ ||\ (R_{E2}+r_e)\ = \frac{R_{E1}(R_{E2}+r_e)}{R_{E1}+R_{E2}+r_e}$$ but I do not know how to show that. I am fairly new to amplifier circuit analysis. Any help is appreciated.


texts: Is there a built in program in any of the top EDA software to ease production of Technical Publications?

texts: I have been assigned to design a PCB and now I have to create Technical Documentation for in-house use. I tried googling this information but it shows the documentation for the software which is not what I was asking for. Software like Siemens Solid Edge have built in support to create technical documentation. Do any EDA software also have this option?


texts:
Is there any code based tools for drawing schematics. I only need to draw some simple diagram, including some 16pin Microcontroller, wire, power supply...

I'd like to use code to specify the pin and components, and let the software do the layout for me. Kinda like define a graph with graphviz dot format.

Some thing I have in mind is:

  define a Microcontroller
  pin1.label="Vcc"
  pin1.goto=other components

How can I design a circuit using a text based format?


texts: (PLL) Why is it essential for VCO to continue oscillating when input is zero?

texts:
I have designed a simple PLL with current-starved ring VCO. The minimum frequency of oscillation for this VCO is zero since there is no current fed to ring of inverters when control voltage is zero.

As described in Chapter on Digital Phase Locked Loops in Jacob Baker's CMOS Circuit Design, Layout, and Simulation (Second Edition, Page 554)

"The frequency of the square wave output of the VCO is Fcenter when Vin(= Vcenter) is VDD/2 (typically). It is important that the VCO continues to oscillate with no input data."

Why is it essential for VCO to continue oscillating when input is zero? It would not be so if a current-starved VCO is used.


texts: What would be the voltage across the across the inductor just after time t=π/wo if the diode wasn't present?

texts:
Basically, this is a diode and an L-C load. Now I was wondering if suppose the diode wasn't there and it was just a source Vs, inductor and capacitor.

Everything else would be the same except when the diode turns off at time t=π/wo. I think the voltage across the inductor would be -Vs if we consider the diode wasn't present at all.
This is the pictures in my book for reference


texts: Transistor Amplifier Signal Drops Off Below 200-300Hz

texts:
I tried to build a dual transistor amplifier from a schematic I saw, and used AC Analysis in LT Spice. What I found was that the current and voltage at my simulated 8 ohm speaker load was dropping off well into the AF range. I understand the RC Filter formula, but it seems like I would need some insane value for capacitance in order to properly drive my 8-ohm load. Any suggestions for how I may be able to remedy this? Thank you.
Below is an image of my LT Spice screen. The green line is the current going through the load resistor. The Blue line is the voltage across the same resistor.


texts:
I don't know a much about electronics so please if you choose to help, layman terms would be appreciated.

I have an old 550w PC PSU. I have used it previously with an electronic air pump to pump up tyres. This electronic pump is made to work off a car battery normally.

Yesterday it just shut off when I applied the pump to the tyre. Now the PSU totally refuses to play with the pump, it just shuts down immediately when the pump is turned on.

I looked at the pump which has a 28A rating and the PSU on the 12v line has a 18A rating. I tried putting all the 12v lines together but that didn't help.


texts:
How to calculate resistance, inductance, capacitor value for dc-dc buck-boost converter when using  with Solar panel? I am working on a project. Charging battery with solar panel with/ without  MPPT. I am doing this simulation on MATLAB with Simscape Power Systems and Electronic Library. Which allows me to choose Solar panel (I am using SolarWorld SW220 mono Pmax=220w, Vmax= 29.3V, Imax=7.51A) and Battery( lead acid 24V, 16Ah). Also, I need to calculate the efficiency of each case. However, I don't know how to monitor battery charging in MATLAB.
I tried to reach tutors online but could find anyone who had knowledge on this subject. If anyone can suggest equation, tutor,website, please, comment!


texts:
In my current project I need to control 8 analog multiplier. They are controlled with SPI but without the MISO line, so I would need to route :

SCK
MOSI
8 slaves selects

So 10 signals in total. The 8 analog multiplier are 1 meter away from the microcontroller, on another PCB. I need to ensure those signals would be rugged against noise. There is no slave to master communication.

I also have two main concerns : power consumption and available space...

What is the best solution ?

At first I was thinking of using RS-485 IC but that would require two many components...

Thanks


texts:
I've setup the behaviour of LIS302DL accelerometer IC using following code:

void initAccel(void)
{
    accelMeterInt.Latch_Request=LIS302DL_INTERRUPTREQUEST_NOTLATCHED;//LIS302DL_INTERRUPTREQUEST_LATCHED;
    accelMeterInt.SingleClick_Axes=LIS302DL_CLICKINTERRUPT_XYZ_DISABLE;
    accelMeterInt.DoubleClick_Axes=LIS302DL_DOUBLECLICKINTERRUPT_XYZ_DISABLE;

    accelMeter.Power_Mode=LIS302DL_LOWPOWERMODE_ACTIVE;
    accelMeter.Output_DataRate=LIS302DL_DATARATE_400;
    accelMeter.Axes_Enable=LIS302DL_X_ENABLE|LIS302DL_Y_ENABLE|LIS302DL_Z_ENABLE;
    accelMeter.Full_Scale=LIS302DL_FULLSCALE_9_2;
    accelMeter.Self_Test=LIS302DL_SELFTEST_NORMAL;

    LIS302DL_InterruptConfig(&accelMeterInt);
    LIS302DL_Init(&accelMeter);

    delay(ACCEL_METER_DELAY);
}   // init Accel

After using this code, I issue WHO_AM_I command with:

LIS302DL_Read(&ident,
    LIS302DL_WHO_AM_I_ADDR,
    sizeof(ident));

Ident contains 0011 1111 after this call, but according to LIS302DL datasheet, it should containt 00111011. Is there something wrong/my code does not work and if so, why? I am using ST32F4Discovery board with IAR Embedded Workbench IDE.


texts: Switching between 2 power sources using just a switch

texts:
So, recently while making a project, I thought of a way to switch between 2 power sources just using a single 3 pin slide switch.
Would something like the image below work?
Where I connect a common ground to the middle pin and 1 power source to each other pin.


texts: Precision voltage clamping 0V to +5V with +/-12V input

texts:
I'm looking for an opamp "voltage clamping" circuit with a +/-12V input and a 0/+5V output.

I mean :
When input < 0V = output stays at 0V
When 0V < input < +5V = output 0 to +5V
When input > +5V = output stays at +5V

Thank you for your help !


texts: New batteries make loud pop sounds after charging?

texts: I bought a new charger and new batterie, nitecore i2 (two bays), and AmazonBasics AAA. I charged in pairs but nearly everytime i do so, one of the batteries is popping during or right after the charge.  When i charge single, no popping. When i charge in pairs, there is popping. Which is faulty, and what should i return?


texts: Running a 12VDC motor for adjustable interval

texts: I want to set up a timer circuit that will run a high-torque, low RPM 12VDC motor (max 200mA) for an adjustable amount of time. This motor drives an auger in a home designed pet feeder and I need to be able to adjust the length of time it runs and pushes out food. I don't need to vary the motor speed. I have been trying to use a 555 chip, but I can't get it to work because I can't find a circuit to copy from that does what I want this to do. Can someone help me with a schematic? Thanks!


texts: Which crimp tool to use with SSH-003GA-P0.2?

texts:
I'm planning to crimp SSH-003GA-P0.2 crimp terminals to go into JSTSHDR-20V-S-B connectors.

How do I figure out which is the proper crimp tool I have to use to succeed?

Thanks in advance.