texts: Rectifying induced current without using any semiconductors

texts:
Consider a 1:1 transformer.

Short DC pulses are applied to the primary (input) coil. Once it's positive current pulse, once it's negative current. It's not strict alternating current (i.e. two successive positive pulses are possible). I want to block negative current on the secondary coil without using any diodes.

Is it possible at all?

I thought about two possible solutions:

connect secondary (output) coil to the solenoid densely wound around a permanent magnet. This way the current flowing in one of the directions will see the resistance, because it will be harder for it to build magnetic field that is in opposition to the magnet's field. Is it the right thinking?
connect secondary (output) coil to DC voltage source so there will be constant DC current in the coil. Positive induced voltage will pass, adding to the existing DC bias. Negative induced voltage will be blocked by the opposite current - or - will it subtract from the existing DC bias?

I'm looking for a way to pass positive pulses through the transformer and block the negative ones without using any semiconductors.

Clarification

Duration of all consecutive pulses is constant. Input voltage is also constant, between 1-5V, but it may drop after being passed through many transformers connected in series.

"Transformers" are supposed to be microfabricated (printed) on PCB as pairs of inducively coupled microcoils. Many of them will be connected in series. It's currently not possible for me to microfabricate semiconductor elements, including any diodes (only copper wires are possible). Also, any vacuum tubes will be too big to use them.

One possibility is to use microwires that are routed to one or few external components, but I don't want to mount an external diode for every microcoil, because there may be many of them.


texts: How to reduce voltage from a high speed buffer?

texts:
I am using this buffer to connect signal between 2.5 V and 5.5 V to a 3.3 V microcontroller.

The problem is I will get a 5 V output and my microcontroller doesn't have 5 V tolerant inputs so I have to reduce it to 3.3 V. The perfect solution would be something like this. It has double power supply, one for input voltage and the other for output voltage so level conversion is easy. But in my country (Argentina) it doesn't exists and buying it at international shops would be expensive (we have lots of taxes).

So, I have the first chip with 5 V outputs and my microcontroller needs 3.3 V. I was thinking of a simple voltage divider with resistors on each output, but the buffer is bi-directional and that will decrease the input voltage to the input.

So I thought of using 1N4148 diodes connected to a power supply of 3.3 V - Vdiode in order to activate the diode if the voltage exceeds 3.3 V. I need a resistor to limit the current in that case? I have clock signals of about 35 MHz, would that affect my signal?


texts: Where to find derivation of s'' (stability factor for beta) for BJTs?

texts: I'm looking for the derivation of the formula for the stability factor (\$S''\$ or \$S(\beta)\$) of BJT bias circuits, particularly the ones with emitter resistance. The book I'm using says that the derivation is too complex and so they didn't include it. I tried to derive it myself but I can't get the same result. Does anyone know where I can find the derivation? I tried googling, but the sources I found say the same thing as my book.


texts:
The above problem was asked in GATE(Graduate Aptitude Test in Engg) 2015 in India.
I have no idea where to start so I can't show my attempt. But through google, I got solution by 2 different coaching institutes
First one - 56.72

Second one - 49.5

IIT(Indian Institute of Technology), the governing body of exam says that the answer will be in the range 60-64V
Please help me with the problem, as similar problems will be asked in the exam.


texts:
Can you tell me what is the appropriate code to send two variables (x,y) from an Xbee to another Xbee (series 1). I configured them and I can't write a code (because I don't know how to receive information and send them via Xbee and Arduino). Xbee is connected to the shield to Arduino UNO in 1st side, on the other side Xbee is connected to another shield to Arduino Mega.

I have configured Xbees yet and I tried to send commands from PC (Xbee) to Arduino (Xbee) and it worked.

Would someone help me by providing me with an example of sending variables (x,y) from UNO to MEGA (I use Arduino program which contain C/C++), or explain how to do it.


texts: Is there a way to make an inverter that only draws power when a load is connected?

texts:
I’m working on a wearable battery project and I think it’s best to use AC power for the voltage and current adjustments, as well as stable transmission over long distances. Because it’s battery powered it needs to be as low energy as possible.
For that reason, I was wondering if it was possible to have the inverter be “always on” but only draw the amount of power needed to run the connected devices. Furthermore, I imagine the inverter itself would draw some power, so I assume it would need to draw power to run itself only when a device is drawing power. Would anything to that effect be possible?
I’m picturing an arrangement wherein a device, for example a fluorescent light tube (I won’t be using one for the project but it’s a common AC load device), would be connected to the inverter output directly. The circuit suddenly becoming closed would allow current to flow and the inverter would begin to operate normally. This would happen without drawing a fixed current, but rather just enough to run the light and the inverter. Ideally all of that would happen without digital logic components being involved.


texts:
I was reading this document talking about the use of superposition with dependant sources.

At example 14 they state the following :

I don't understand how they pulled the equation for Vo by inspection only. They seem to be using the equations for the non-inverting and inverting amplifiers. However, for the non-inverting step, it's as if Vo is grounded (zero).
For the inverting step, they seem to consider the V+ of the op-amp as grounded (zero), which should not be the case because of the RC network.

What's going on behind their reasonings? Could someone explain it to me step by step?
Thanks!


texts: Can a motor's movement be improved to any arbitrary resolution?

texts:
For a project that I'm working on, I need motor rotation at extremely small increments -- my desired resolution is about ~0.15 degrees per minimum rotation step.

Of course, most motors of reasonably cost don't offer this much precision, so I am trying to see if I can reach my goal using closed-loop movement with a low-cost motor.

Let's say I have access to output data from an encoder that can measure rotation to my required resolution (i.e., down to 0.15 degrees incremental angle).

My question then: Is it possible to interface such an encoder (its data forming a feedback loop) via a microcontroller to a motor, and get to any arbitrary desired resolution, or are there motor-mechanics based limits to achievable precision?

In terms of motor choice for this particular method:

Steppers: I suppose steppers are not an option since they are designed to move in certain-size steps and, even with my feedback encoder, I cannot instruct the stepper to stop in between steps.
Standard DC motors: Could I use my encoder data and then do a PID loop to move the motor and zone in on the target angular position each time? I suppose the settling time might be too long?
Servos: Could I add my own closed-loop control using my encoder either in addition to, or replacing the pot of, a cheap servo with low resolution? Thus getting it to move/step at my target improved resolution. Or are there design-specific limits to how precisely a given servo can move, which I cannot overcome?


texts: Weird schematic with MOSFET bulk connected to some negative terminal

texts:
I found a circuit diagram, which I do not understand. In the diagram below, I bounded a peculiar terminal with a red box. The bulk of m3 and m4 MOSFETs are connected to this negative terminal.

My question is, what does this mean? Does this mean that the bulk of m4 and m3 is connected to some terminal that has a potential lower than VSS?
I appreciate any help.


texts:
I'm analyzing the circuit in the picture below. I've read a little about unity gain amplifiers/buffers and think I understand the use of a single buffer.
But I don't understand the purpose of having two buffers, one after the other.

Here are some more info about the circuit:

OPAMPS: MCP6002, A and B are in the same package
Input is from a 4 .. 20 mA signal (4 mA = 0.88 V at OpAmp-A's input, 20 mA = 4.4 V at OpAmp-A's input)

My questions:

Why have two buffers or what is the designer trying to avoid by using two?
What is the purpose of the 4.7k and 1k resistors? I.e. what will happen if I change, lets say the 4.7k to a 1k?
Same as question 2 but regarding the capacitances 100 nF and 10 nF


texts: High Inrush Current Causing Large Voltage Spikes

texts:
I have a H-Bridge driving a 1200VA 20 kHz transformer. The H-Bridge is rated for 1000W (24V, 42 A). The circuit works very well when VBatt is 14V but the FETs die whenever VBatt is 24V. I found out the reason for this: the capacitor C9 causes a large inrush current (high dI/dt) which in turn causes a large voltage spike on the output of the H-Bridge. The voltage spikes when the circuit is operating at 14V are approximately 38V - the FETs are only rated for 40V and I have already changed these to a 60V part. The spikes at 24V are of course double, ~70V. This is killing my FETs.

If C9 is removed or charged beforehand the circuit experiences no voltage spikes and holds upto 400W load (that is how much I've tested so far) with > 90% efficiency.

My question is, how do deal with the voltage spikes?

The simplest solution seems to be to add a NTC thermistor on the high voltage section - perhaps in series with C9?
Use a FET based inrush current limiter which slowly ramps up the 24V input. However, having the load disconnected at the capacitor will be necessary as otherwise I will need a massive FET.
Use an aux. timing control circuit which, when first powered up, charges C9 through a fixed resistance via a relay and then after some time switches the relay such that the diode bridge is connected directly to C9.

What is the best approach for this sort of power? The circuit is a 24V to 350VDC booster which provides a high voltage rail for an inverter to modulate into a sinusoidal 50 Hz 240V waveform.

Larger schematic: http://imgur.com/tZ2CYvZ.jpg


texts: Total Resistance of series parallel circuit

texts:
I made this circuit in Multisim it gives the total resistance 2.647kohm. but theoretical calculation gives 2.49kohm.
I need to know why Multisim gives greater value or my theoretical value is wrong.
NOTE: theoretical calculated from right to left.

Here's my work


texts:
I'm trying to generate parallel output by writing serial data into a shift register (SN74HC595) via SPI on an ATMega328 (SPI master) running at 20MHz and SPI running at 10MHz. The bare minimum schematic to reproduce my issue is below (VCC = 5V).

The code generates the correct waveforms as viewed on an oscilloscope but the SN74HC595 does not appear to be clocking, or is interpreting the data differently to how I expect.
I have observed that the serial output QH' is always a logic 1, and so are the parallel outputs QA through QH.

I have reduced the problem to the following bare minimum code which configures SPI in master mode, MSB-first, and SCK = \$f_{osc} / 2\$:

    #include <avr/io.h>

    volatile uint8_t counter = 0;

    int main(void)
    {
        DDRB = (1 << PINB3) | (1 << PINB5) | (1 << PINB1);
        SPCR = (1 << SPE) | (1 << MSTR);

        SPSR = (1 << SPI2X);

        while(1)
        {
            PORTB &= ~(1 << PINB1); //pull SS low

            SPDR = counter++;
            while(!(SPSR & (1 << SPIF)))
            {
                ;//Busy wait
            }

            PORTB |= 1 << PINB1;    //pull SS high
        }
    }

This generates the waveforms SRCLK (yellow), SER (cyan), and RCLK (magenta). The oscilloscope correctly decodes the data as a sequence of ascending bytes so the SPI transmission appears to be working correctly.

Further detail of a single byte transmission is shown in the following screen capture. Note the clock period of SRCLK is 100ns, which matches the SPI clock rate of 10MHz. Also note that RCLK (not shown here) is held low for 200ns between successive writes and high for 1600ns during each write.

I have tried:

Increased decoupling
Reduced clock rate - both system clock and SPI clock
Swapping another SN74HC595
Reversing pull-ups/downs on the active-low pins OE and SRCLR in case I have confused the two pins

I don't appear to be exceeding the timing requirements of the SN74HC595 and the behaviour is the same if the CKDIV8 fuse is programmed to 1. The SPIEN fuse is also set to 1.

What are some possible reasons for this behaviour?

Interesting note: if I bit-bang the same interface, the shift register operates as expected - though the performance is obviously not great.


texts: Insert Arduino into Thermostat circuit, but no common

texts:
I thought I was all ready to replace a thermostat with an Arduino. I used a multi-meter and bridged some connections to discover the following:
1. bridging 230V (live) with Cool turns on the Aircon outside unit
2. bridging 230V with F2 (brown) turns on internal fan on LOW

Now I would like to insert an Arduino into this circuit, powered from the 230V (using AC to DC module) and not from a battery. The Arduino will control a relay module. Then I realized I do not have a common ground for the Arduino (actually NodeMCU).

The only way to have power run through this circuit is to bridge 230V with either Cool, F1, F2 or F3. I would like to have the Arduino powered on even if the Airco / Fan are not on, since the Arduino should control the relay.

I have two questions:
1. can I use one of the Fan lines as a "common" since it is lower voltage than the live wire?

Like this:

I assume that in this case there may be some "trickle" of power running from Live to Fan through the AC-DC module. As long as it does not consume a lot of power and does not break the fan I would not care too much. Is this right or am I making a mistake here?

Are there other options to make this work, without running further wires or using a battery?


texts:
I'm a beginner with electronics, so everything has to be explained in simple terms to me.

I have an Arduino with a program which provides a value via the Analog output, so that is anything from 0-5 V.

On the other side, I have a VFD with an IO card which allows it to connect to a 4-20 mA current loop, to vary the speed of the motor accordingly.

How do I convert from, let's say, 0-5 V output (PWM) from Arduino, to the 4-20 mA in a somewhat cheap and safe way (I don't want to destroy the VFD [and possibly the Arduino])?

Currently, I am using the circuit below:

The problem is that the simulation on "Multisim" is giving accurate results. However practically, the circuit did not give the accurate results.

For example:

When V = 5 V output (from Arduino analog), I = 20 mA (V=IR) --> which is correct
But, when V = 3.3 V output (from Arduino analog), I = 16 mA (V=IR)--> which is incorrect, as it should be 13 mA

Will this circuit work practically


texts: Rigol DS1074 oscilloscope shows very wrong timing

texts:
I have an inverted RS232 signal with 5 baud (200 ms per bit) which is sending the byte 0x33. (The first "Low" is the start bit)
When I configure my oscilloscope to 200 ms per unit it shows this signal absolutely perfect.
I use the single trigger mode (button "Single" at the right top)

As you see the timing is precise.
Now comes the weird: I caputure the same signal with the setting 500 ms per unit. It looks like this.

To see the timing better I switch the timing to 200 ms per unit for the SAME capture and get this:

As you see the signal seems to be slower than 200 ms per bit now.
How is that even possible on a digital oscilloscope?
In the first step the oscilloscope stores the captured data in memory.
In the second step it displays the data.
All timing is based on a precise crystal oscillator.
The only difference which I see is at the top of the screenshot where it says:
Correct capture: 10.0 MSa/s and 24.0M pts
Wrong   capture: 4.0 MSa/s and 24.0M pts
The only explanation to me seems to be a fat software bug. Are the Rigol engineers not able to do the correct conversion to display a 4.0M Samples signal? How did this oscillocope series even pass the quality control?
And yes: I have made sure that my signal is precise.
I can repeat that a hundred times:
Capturing with 200 ms per unit is perfect.
Capturing with 500 ms per unit gets wrong.
P.D:
Now I tested more time bases. These are the results:
5 seconds per unit --> OK
2 seconds per unit --> OK
1 second per unit --> OK
500 ms per unit --> wrong (constantly 4% timing error)
200 ms per unit --> OK
100 ms per unit --> OK
50 ms or less --> a period does not fit anymore

But this is just one of multiple bugs. The oscilloscope has several more bugs.
When you enable the RS232 decoder and the horizontal resolution is too small it is understandable that it does not show the hex bytes. But this is implemented so buggy that it displays completely wrong data! This screenshot shows a RS232 signal with 10400 baud and long pauses between the data packets. All the displayed "FF" are wrong.

And one of the ugliest bugs is the knob "Horizontal Position". This is complete crap. It should move the signal horizontally on the screen. But it works so bad that moving the knob fast results in the signal suddenly jumping to a completely different loaction. When you move it slowly it nearly does not move at all. Such a basic functionality as navigating in a long capture with a Rigol oscilloscope is a pain!
And when you move that knob too fast you get suddenly artifacts in the signal. The same signal which I caputured above, suddenly looks like this:

Amplifying this bug you see a square signal of 2 ms period. This signal has never existed on the input of the oscilloscope. It is produced by a software bug in the oscilloscope just by moving the captured signal in memory horizontally on the screen!! Here you see a zoom of the left artifact:

And this is a zoom of the right artifact:

And as if all this would not be enough, there are more bugs. All these bugs are not reproducable. For example:

There is a signal but the oscilloscope does not trigger. It triggers mostly, but not always.
The "Single" trigger mode is enabled, but the scope does not stop after the screen is full.
It happened that I plug in a USB stick and the oscillscope completely freezes. All buttons were dead.


texts:
I am repairing a "wall-wart" charger for a Black and Decker battery powered edger which uses a 12 volt/7 amp hour battery.  It has ceased to deliver charge current to the battery but the half wave rectified current is present at what I think is the emitter of a TO92 cased device labelled "S8550".  I have found confusing information trying to identify this device.  I found a reference to an "SC8550" that is listed as a PNP silicon transistor but I have never seen an SC designation without the preceding "2". It does not check as a "good" PNP transistor using the DVM and I don't have access to a curve tracer.

Does anyone have experience with this "transistor"? If the info I found is correct then I guess I can search using the max ratings to find a sub. It is the only transistor on the small circuit board which also contains a quad op-amp.

I don't have a circuit diagram/schematic and I am unable to determine the purpose of this device except maybe it is a switch to supply charge to the battery until it reaches a specific charge level?  Is it likely that a TO92 cased device would control current to charge a 7 amp hour battery or might this be a voltage reference?


texts: How much power does a cell phone charger actually use?

texts:
I was trying to figure out how much power I actually use when I am charging my phone. Here are the specifications of my charger:

Input: 100/240 V, 50–60 Hz, 0.15 A
Output: 5 V, 0.7 A

I've heard that in order to calculate this, you need to pay attention to the input.

$$P = V\cdot A = 240\ \mathrm V\cdot 0.15\ \mathrm A = 36\ \mathrm W$$

I charge my phone for 4 hours a day at most. In that case, I use 144 watt-hours a day, and 51840 Wh a year, or 51.84 kWh. And that seems awfully lot, considering that all the articles I've read about the power consumption of chargers stated that they used about 2 kWh a year. I know I charge my phone too much (I really need a new battery), but it still doesn't add up. Are my calculations wrong? And if they are, what is the correct number?


texts: Creating SystemVerilog module using for loop and separate custom module

texts:
I am trying to create an n-bit barrel shifter using the diagram in the answer to this question: https://stackoverflow.com/questions/26551049/vhdl-n-bit-barrel-shifter

I've read that if the variable in a for loop has a single name, then each loop iteration has a separate scope and a separate variable; however, I'm not sure whether the rows in my barrel module will be created in the same style as the reference diagram from above. This is my barrel module:

module barrel
    #(parameter n = 8; parameter control = $clog2(n))
    (input logic[n-1:0] data, input logic [control-1:0] select,
    output logic [n-1:0] result);

    for(genvar i = 0; i < control; i++) begin : label
            logic [n-1:0] tempResult;

            always_comb
                    if(i == 0) row #(n,2**i) shiftLevel(data,select[i],tempResult);
                    else if(i == control-1) row #(n,2**i) shiftLevel(label[i-1].shiftLevel.tempResult,select[i],result);
                    else row #(n,2**i) shiftLevel(label[i-1].shiftLevel.tempResult,select[i],tempResult);
    end

endmodule

My question is this: will the labeled for loop preserve the row modules that I create in each iteration? Or does each row get destroyed once the iteration finishes?

Here are the other modules that I'm using to implement this:

row module:

module row
    #(parameter n=8, parameter shift=4) // n is the number of bits
                                            // shift is the max amount of shift at this level
    (input logic [n-1:0] data,
    input logic select,
    output logic [n-1:0] end);

    for(genvar i = 0; i < n; i++) begin : label
            logic [1:0] dataTemp;

            always_comb
                    dataTemp[0] <= data[i]; // 0 option of the mux is set to the normal data value

                    if(i+shift < n) dataTemp[1] <= data[i+shift]; // assigns the shifted bit
                    else dataTemp[0] <= 0; // assigns 0

            mux2 bit(dataTemp,select,end[i]); // Assembles a mux for a bit of the row output

endmodule

2-1 Mux module:

module mux2(input logic [1:0] data, select,
            output logic y);

    assign y = select ? data[1] : data[0];
endmodule


texts: Earth connection missing on electric circuit, getting lots of noise with audio equipment

texts:
I have a question today that possibly crosses to another website, but i'm interested in your expertise here. It's more or less about music, but also about noise and electric current.

Basically, I have a band, we rehearse in an old garage, where there is no earth connection and the house attached to the garage is about 50 meters away (straight line, not counting the curves and other implications for connecting a wire there.), which makes it a lot of cable to buy, adding to the cable we will already have to buy in order to connect all the outlets... (we're on a 20 yr old student budget here...).

My grandfather told me once he has a copper tube around that he used to ground an irrigation pump motor. He just sticked the tube in the ground near the motor and it would eliminate the chance of getting him electrocuted when he had to touch the motor.

My question is, could this work for eliminating the hum and noise we get on our instruments? It gets awfully noisy in there with 2 guitars connected.

It would come out cheap because we don't need to get the copper tube, my grandfather told me we can take his as he no longer needs it.

Is it feasible? Would it work? How can I do it?


texts: Need help identifying this SMD component

texts:
Does anyone know what this is? It's an SMD taken from a Citroen 2.0 BlueHDi AdBlue ECU that's faulty.
https://i.stack.imgur.com/YZZN9.jpg! [the mosfet is to
Top left above Q111. The TVS is the big SMD next to D100]


texts: I am using CS43L22 with STM32F4 discovery board. I generate sounds by sending I2S messages to CS43L22 using circular DMA buffer (32 size array). However, chip creates a constant beep whether it's playing a sound or not. What I also noticed is that if I decrease the buffer to 16, beep gets doubled in frequency, if I send 8, it gets doubled again like that and It is a pulse wave. Thus I have concluded that it is DMA related with I2S operation and It changes the the signal after the buffer is finished sending, or it accidentally sends 1 bit of information at the end of every DMA operation. What might be causing this?


texts:
I am looking to design an Antenna (MIFA) for BLE (2.4GHz) in Kicad. But I can't find it in libraries. Even we can't design footprint of custom shape with Kicad Footprint editor. Can somebody help me in designing antenna?

EDIT:

My question is about designing a custom shape in kicad so that I can design MIFA antenna of required shape and size. The question is not about How to design MIFA antenna for BLE. I can't find anything in Kicad to design a pad of custom shape.


texts:
I've seen this capacitor:
https://api.kemet.com/component-edge/download/datasheet/C0603C221JDGACAUTO.pdf

It is a 0603 capacitor with a 1000VDC rating. As I am familiar with IPC2221, this did not sound right.

As can be seen here: Minimum clearance between two traces that have a potential difference of 1000VDC
The separation of two 1000V uncoated conductors should be at least 200mils. 0603 capacitors have only 20 mils separation! How can this be?


texts: How do I connect the edge connectors on the PCB to a breadboard?

texts:
How do I connect the edge connectors on the PCB (shown in the below image) to a breadboard ?
Are there any standard breakout boards or Adaptors available for this purpose ?

Link to the user guide of the PCB


texts: What is the advantage of using Logic Shifter ICs over just building it with NMOS Transistors?

texts:
I was browsing the internet for SD card module schematics for a board I am developing that should read and write data to an SD card. I realized that these modules use specific ICs to convert 5V logic levels to 3.3V. The logic level shifting circuit that I know and usually use looks like this:

For comparison here is a link to the adafruit sd card reader module:

https://learn.adafruit.com/adafruit-micro-sd-breakout-board-card-tutorial/download
What is the advantage of using a chip like "CD74HC4050" in certain designs? After a quick search it seems to me that using the IC over the Mosfet is also a couple of cents more expensive. Is it that the IC is faster? In that case the "CD74HC4050" has a typical propagation delay of 6ns at 5V Vcc while according to the datasheet of the BSS138 it has a turn on delay time of 2.5ns to 5ns and a turn off delay time of 26ns to 36ns. Is it the turn off time that makes it better to use the ICs? I checked 2N7002s datasheet too for comparison. It says that it has a max turn off time of 20ns. Is this a typical characteristic for most commercial NMOS Transistors, which makes them undesirable to use in such applications? I use the level shifter circuit above for all I2C 3.3V to 5V Communication Lines I put in my PCBs, so does Adafruit. So I dont really understand the difference to this case. I would appriciate any thoughts on the matter. Thanks in advance.
Datasheets Of BSS138, N7002, CD74HC4050:
https://www.ti.com/lit/ds/symlink/cd74hc4050.pdf?HQS=TI-null-null-mousermode-df-pf-null-wwe&ts=1604306661514&ref_url=https%253A%252F%252Fwww.mouser.it%252F
https://www.onsemi.com/pub/Collateral/BSS138-D.PDF
https://www.onsemi.com/pub/Collateral/NDS7002A-D.PDF


texts: LED characteristics to use in heating a material sample?

texts:
I am looking to be able to heat a sample of material, typically less than 500mg and sitting in a fused silica sample holder about 10mm diameter. Wondering about using (say) a 5W LED with narrow emission angle. The overall sample chamber of the machine is quite small, so ideally I need a small source, possibly with a light pipe. I certainly do not want the thermal mass of something like a halogen bulb. So, the questions...

Does this seem feasible?

What type of LED (in terms of wavelength) is the most efficient?

Does wavelength matter in terms of heating the sample? [Typically the archetypal "white powder"]

Now, I expect you to ask me what sort of temperature I want to get. The answer is "not sure", but probably 80 degC would be adequate. It is to drive off moisture.

The only cooling I have is a small ambient temperature airflow. Other possibilities (that I have not yet examined in detail) are low power uwaves and maybe changing the pan from silica to steel and using induction heating.


texts:
So i've been urging to really expand into the embedded field, I have a CS degree but sadly....I only had 2 EE Classes.
I have the books:

Computer Architecture: A Quantitative Approach, 4th Edition and
Computer Organization and Design, Fourth Edition: The Hardware/Software Interface

However My EE classes were.....lets say lacking, not to mention I never had time to attend the optional labs (because of other classes). But I REALLY really want to learn the low level in CPU design. Im talking low level TTL design, however I don't really know any of it from College, and honestly....I see alot of "Cool" homebrew CPU's people have built, but nothing on HOW it's done. Keep in mind my Electronics knowledge is limited.

So how would I go about doing this, would those 2 books above help? Any other book suggestions? Im talking about something really basic, like a 4 bit or something. I can add to it as time goes, but even something super basic would be great.

Thanks


texts: What's the difference between a LM3302N, TLC373CP, and LT1101CN8?

texts:
So I’ve got an LM3302N (IC COMPARATOR QUAD DIFF 14-DIP), LT1011CN8 (IC VOLTAGE COMPARATOR 5-V 8-DIP), and a TLC373CP (IC DUAL DIFF COMP 8-DIP) and I want to build a circuit inspired of the “1 minute of power” circuit in the Art of Electronics 3rd Ed.

I looked at the data sheets and I only understood the maximum voltage and I/O current ratings. I’m at chapter one in AOE. I’ve read about 700 pages textbook, so some of the data sheet, buffers, and comparators were not incomprehensible.

I think they would all work as long as I don’t exceed 20mA and LT1011 is confusing me with it’s title “voltage comparator.”
Sorry if this was too lengthy for you, I’m just getting into electronics.
I appreciate any input about data sheets and these chips, keep in mind I’m working through these textbooks.


texts: Improve Smartphone GPS with external RTK - will a simple antenna work?

texts:
Regarding RTK technique, if you have appropriate equipment for full RTK you will have up to cm accuracy. I wondered if we can use very simple external to device antenna (I'm not speaking about Garmin GPS device style build in antennas like we all had in past mobile phones) communicating with the smartphone via wifi/bluetooth/rfid + software layer running on the smartphone, to somehow take advantage on RTK technique in order to improve current GPS accuracy which is ~3 meters to let's say even something like ~1 meter?

We will compromise accuracy by using very primitive external hardware - So is a simple antenna relevant somehow for RTK technique?

Thanks,


texts: Can R-783.3-0.5 DC-DC converter be used with 5V input?

texts:
I need to use a DC-DC converter to obtain 3.3V/100mA from a 5V supply. I have a R-783.3-0.5 available, but I am not sure if it can work with 5V input.

The datasheet says that the minimum input voltage is 4.75V, but note (5) says: "The R.783.3-0.5 requires Vin>5.5V to meet the Transient Response specifications". I do not understand what it means.

So, can this converter be used with 5V input or not?


texts:
I have a resistance based sensor which gives the resistance change when the strain/force is applied. How to measure the unknown resistance change using the Wheatstone bridge circuit.? I mean what are the important things we have to keep in mind while selecting the resistor value.
The initial resistance of the sensor is not the same. it always give the creep resistance value while no force is applied or under the constant load/Force/strain.


texts: Why does my HV monitor circuit (sometimes) fry components?

texts:
simulate this circuit – Schematic created using CircuitLab

I have a high-voltage monitor circuit that illuminates an LED when HV is present, shown above.  A couple of these boards have worked fine for months, while others exhaust a burning silicon smell and draw 500+mA before constant-current mode kicks in on my power supply.  All of the boards of a previous revision worked fine with an LM1717 op-amp instead of the LM339, but I moved to a comparator for rail-to-rail operation.

Probing this board is pretty tough, and due to safety restrictions I cannot use the finger test to determine which component gets warm, but I know the Zener regulates 10V fine at steady-state.

My thoughts are:

Do Zener diodes, in general, have a slow turn-on time?  I cannot find any literature on this, in datasheets or otherwise.  If so, I could see a high enough voltage develop on the input pin of the comparator to fry it (~50V).
If so, a small capacitor on the input pin to the comparator could limit the voltage rise until the Zener can start regulating.  Is this valid?  Since this is only for a human's eye, a few milliseconds of delay on the turn-on/-off won't matter too much.
Would a resistor in-line with the input pin help, too?  Say 1k?
Is there some other phenomenon I'm not thinking of?


texts: Can a comparator (LM393) be used as an amplifier?

texts:
I have seen modules for microphones (such as the one below) that use the LM393 and claim to have amplification.

I have looked this part up and it is a comparator. I have read that op amps can be used as comparators, but I don't understand if the other way is also possible. My understanding is that comparator only outputs V+ or Gnd.

Can a comparator or this LM393 specifically be used as an amplifier for microphone signal? What parameters in the spec will make such a comparator applicable for use as an amplifier?

Update:
I have traced the connections on the module and made a schematic. It is based on my best effort and might not be accurate. Seems that the LM393 in this case is not used to amplify the analog out only to digitize it. I guess the general question still stands though.


texts:
If I have only starting values a U_high=3V and U_low=2V (pulse signal on V3 on schematics), can I determine a U reference, that's given us on the inverting input of the op. amp.?

My calculations were: Uref = (U_high - U_low)/2 = 2.5V. Is that correct?

I had difficulties from here on, because I got different values for R2 (which aswell I have to calculate) when I calculated R2 based on Uhigh and different when based on Ulow. How is that even possible?

This is supposed to be an ideal operational amplifier.

This is not a homework, but preparations for an exam.

simulate this circuit – Schematic created using CircuitLab


texts: How to indicate Low voltage(2.7kV) and normal voltage(above 2.7kV) in 3.3kV 10uA power supply through LEDs

texts:
I have a power supply which gives 3.3kV 10uA output. Now what i need to do is to turn ON a Green LED when the voltage is above 2.7kv and turn red LED ON when it goes below 2.7kV.
Could anyone guide me how am i supposed to detect such a huge voltage and indicate it on LEDs. One solution i thought was to use a voltage divider circuit of 2.74Mohm and 10kohm resistor to it to 12v.
Is it a good approach.
If yes then how can i detect and show it on LEDs that the supply voltage is below 2.7kv or 3.3kv.
Thanks in advance.


texts: I need to design a circuit so that it can convert 0 - 80 V DC to 0 - 3.3V DC. I need to give the output of a battery which is in the range of 0 - 80 V to an STM32F103 microcontroller. Since the operating voltage of the STM32 is 3.3V it is not possible to directly take the output. I need to convert it to a range of 0 - 3.3 V in order not to blast the controller. Can you please suggest a method to do that. Is it possible to achieve it using potentiometers. If yes can you please explain how the circuit should be?


texts: Check if power network is up, having my circuit powered via UPS

texts:
I have this circuit bellow in the image, I want to monitor if there is power in the room. I have arduino mega powered by a UPS, so if there is no power in the network, the sensoring will still continue for some time. The PN 5V pins are 5V taken by a 'power supply' a normal 5V phone charger, plugged not in UPS but straight to a plug. I use this resistor voltage divider, provide ~3.2V. Is this circuit viable or alterations are necessary?
The thought is that if there is power in PN pin there will be 5V translated to 3.3V, if there is no power there will 0V so arduino will perceive it as logical 0.


texts:
I was looking at the schematic of the LPCXPRESSO LPC1769 board from NXP and I couldn't figure out what they meant by "not mounted" which appears on the left corner of the following picture.

Here's a link to the full pdf document (page 3):
http://www.lpcware.com/system/files/LPCXpressoLPC1769revB.pdf


texts: Microcontroller + Triac without an optoisolator

texts:
I have a project that needs to be in use on saturday (afterwards I'll be able to complete it properly) and my optoisolators haven't come in yet.

I'm using an arduino to switch mains power (on/off) using a triac, Is there anyway to safely wire the microcontroller to the triac without using an optoisolator?


texts:
We are doing a prototype for a gps based tracker. We got a problem in placing the GSM and GPS antenna. Both the GSM and GPS antenna are omni-directional antennas. In forums and application notes, the standard isolation between GPS and GSM antenna is given as >20dB.

How can we measure this dB unit in length. We need to find what could be the minimum separation in millimeter between the two antenna, so as to keep the interference between the GSM and GPS very minimal.


texts: Is there a way to use Arduino PWM signal to supply a varying large current through a restive heating element?

texts:
I am working on a simple Arduino based project where I will use PID to modulate the PWM signal of an Arduino microcontroller, so the PWM values will vary from 0 to 255, as that is the resolution. I will be using AnalogWrite ( PWM voltage ) to out varied voltages. So my question is this, suppose I need a 12 V power supply that is connected to a resistive heating element, how would I control the amount of current flowing through a heating element. Note that I have already developed a on/off system that supplies maximial current, when I set the PWM to 100 % duty cycle and zero current, when I set the PWM to 0 % duty cycle.

I talked to my supervisor and he told me to connect the PWM to a mosfet and vary the PWM which will allow a varying current to flow through the heating element ( resistive).

Is this a good idea and will this work?


texts:
I am currently in the middle of migrating a project from PIC16LF1947 to a PIC18F87K22 as I am in need of extra GPIOS and the PIC18 part fits the bill. There is one thing that is nagging me right now is the internal ADC reference of the PIC. The PIC16LF has an internal bandgap reference. I tried to post a screen shot of the datasheet snipped but looks like I need more reputation to do that. REf- PIC16LF1946/47 page 4 Voltage reference module:.

It is nice in the sense that it lets you program the internal reference in increments of 1.024V. Now, the PIC18F has an internal bandgap reference too, but the datasheet is not divulging too much information. I spoke to the MCHP tech support and it was futile. At this point I would like to know how to set the internal BGR for my ADC conversions.


texts: Did I interpret these multisim results correctly?

texts:
From the circuit above, this is what I have to do: " Connect the circuit with R3 equal to 470 kΩ. Set the input frequency to 100 Hz. Adjust the signal level to get an output of 5 Vp-p. Record gain and upper cut off frequency. Multiply gain and bandwidth."
What I did was this:

I used a function generator and made the frequency to 100Hz. As for amplitude, I chose 1.25 Vp so that in   PR1 it shows 5vp-p (I drew a red arrow and labelled it as 1 to make it easier to locate). This is what it meant by "Adjust the signal level to get an output of 5Vp-p" right?
Next, in order to get the gain. I placed a probe (PR2) at the output and made PR1 as the reference. Then in the list of values, there's a V(gain_AC) which is equal to 5.66 (Again, I drew a red arrow and labelled it as 2). Is this the gain of the circuit already?
Lastly, to get the cut off frequency I did an ac sweep and located where it drops by 3db (I already changed the vertical scale to decibels). The result is the following:

Is the value that I highlighted which is 2.1348k the upper cut-off frequency I'm looking for? And, this is also the bandwidth right?
To sum it up, I basically have three questions:

Was I able to adjust the signal level properly to get an output of 5 Vp-p?
Is the V(gain_AC) shown by the probe, the actual gain of the circuit?
In the AC sweep I did, is the value I highlighted the upper cut-off frequency and the bandwidth?

If you need more information, please tell me. Thank you so much for your help!


texts:
I have this 5 pin 3.5mm Stereo Jack Socket, and I don't know what pin is the left, right and the ground.

Can anyone make arrows on this picture showing every pin label??

Sorry just a newbie :/


texts: what is microcoded architecture in computer architecture

texts:
I want to know what is microcoded microarchitecture of an instruction set architecture (ISA) and why is it used? What is the difference between microcoded architecture and single cycle microarchitecture?

Please clarify with some examples.

Thanks


texts: 5 ma to 2 amp variable current circuit using TIP120 BJT. Please analyze my circuit and comment

texts:
I'm trying to build a circuit that can output current from 5ma to 2Amps using BJT TIP120. Voltage is 18v and constant.

I tried designing a simple circuit. Please check the image below and let me know your comments. Thanks in advance.


texts:
I am an RF noob and am trying to understand if optimizing an AM crystal radio antenna (maximizing the signal transmission from the antenna to the LC tank) is practical, or even makes sense. Here is a schematic of the circuit I am working with:

My approach so far has been to treat my (theoretical) antenna (long wire) as a transmission line, and treating the LC tank as the load of the transmission line. In order to keep things simple, I have not considered loading by the diode. I reviewed a little literature about transmission line termination/impedance matching, and it seems that there would be some impedance value (implemented as a resistor between the antenna and the tank) which would maximize signal transmission at a given frequency.
Here are my questions:

Does treating the antenna as a transmission line make sense?
If so, how is the characteristic impedance of the antenna calculated?
In adding a terminating resistor between the antenna and the tank, I would be making a voltage divider because I would 'read' the voltage between the tank and resistor i.e. this is where I would connect the diode. Would this potentially offset any gains I might make by impedance matching between the antenna and the tank?
It seems that optimization may only be possible for one tank impedance, and, by extension, one specific wavelength. So, any 'optimized' design would only be able to listen to one radio station, and therefore not be useful even if it did work. Is that correct?

Thanks!


texts: Why do some Integrated Circuits get so hot?

texts:
I was reading an article about Radeon 6990 recently and it was recommending 1200 Watts of power supply and the entire machine to be kept dipped in mineral oil because air cooling would kill it in a few months if not. My question is why are chips converting so much electricity into heat? What does physics say into this and is it not possible using the very advanced technologies we have today to make our chips a bit more efficient?

Edit1: I am hoping for a technical answer. Apologies if that was not evident in the original question.


texts:
I try to read out data from the AS5047U sensor (https://ams.com/documents/20143/36005/AS5047U_DS000637_1-00.pdf/8639418f-6c3a-1624-4e6f-18f52c962099) over SPI, but somehow my CRC is always different than that from the sensor. I can read out the correct position value and the crc value from the sensor and the crc stays the same for the same position value, so I think I got the right frame for crc.
I got for example the following values from my crc calculation and the crc given by the sensor (spi1.data is the received data over spi, spi.cmd is the sent data):

Any ideas what could be wrong here?
SPI crc processing:
rx_spi_16(&spi1.data[0],&spi1.cmd[0],2);

pos_sensor.crc = (spi1.data[1] >> 8);

uint8_t crc = crc8((uint8_t *)&spi1.data[0],2);

TX Command to send (16bit mode):
spi1.cmd[0] = 0x7FFF;
spi1.cmd[1] = 0;

CRC Calculation:
uint8_t crc8(uint8_t *message ,uint8_t length)
{
    uint32_t crc;
    int16_t i,bit;

    crc = 0xff;
    for ( i=0 ; i<length ; i++ )
    {
        crc ^= message[i];
        for ( bit=0 ; bit<8 ; bit++)
        {
            if ( (crc & 0x80)!=0 )
            {
                crc <<= 1;
                crc ^= 0x1D;
            }
            else
            {
                crc <<= 1;
            }
        }
    }

    return (~crc) & 0xFF;
}


texts: ATmega1284 running very slowly until reflashed

texts:
When I power up my ATmega1284, it executes extremely slowly -- probably less than a tenth of its normal speed, judging by the cycling LEDs it runs. It's configured to use the internal oscillator with no divider, and I have confirmed that CKOUT is giving an 8 MHz clock.

Resetting it doesn't help, but if I ISP it (just flash, not fuses), it suddenly starts to run at full speed again. lfuse is 0xA2 (internal RC oscillator, no divider).

What is the likely cause of this? What else should I test for?


texts:
This is from a microchip datasheet

What is a tank capacitor ? It doesn't sound like a tank circuit because why would they use "capacitor" and not the other element in the tank.


texts: Iso DC-DC PCB heat dissipation technique proposal

texts:
I'm designing a custom 8-Layer board. The main power supply is based on a 24V-12V Iso DC-DC (Tracopower TEN 40-2412WIR). I'm a little concerned about the heat generated by this device because it's gonna be operating almost at full load in a close environment (no forced air allowed).
The datasheet of Tracopower TEN 40 specifies a non-conductive FR4 material for the baseplate: this makes me think that the device was designed to dissipate most of the heat generated by the top of the device itself (because of copper case), using a heatsink.
I'm evaluating some ways to spread as much heat as possible far from this device without a heatsink on top of it.
I was thinking about using the GND pin of the DC-DC to help conduct heat away from the converter to the main PCB, using a region outside the DC-DC in contact with the ground polygon (on the layer immediately below it). In this context, I planned to place an exposed pad to hook the convection under the Traco case, as per attached figure. It should favor the dissipation along the dedicated polygon outside the component footprint.

I don't know if it can be a good or a completely useless idea. Alternatively, are there other ways to spread heat away from the DC-DC converter?


texts: Can a Transformer Have Multiple Secondary Coils?

texts:
Can a transformer have multiple, isolated, secondary coils from a single primary coil? Can each coil have a different voltage from the other? If so, is there any large negative effect, and what is the behavior as the load increases?

Related: http://engineering.electrical-equipment.org/electrical-distribution/multiple-winding-transformers.html


texts: Will this Cooler Master i70 CPU cooler work for Peltier Module TEC12706?

texts:
I am trying to make a Peltier cooler using TEC12706 and CPU coolers, the data sheet doesn't mention the cooling capacity of the cooler.

Cooler Master i70

A TEC12706 typically works on 12V and takes 4A i.e. a load of about 50W has to be removed by the cooler.

Will it be able to do the job or I have to move to better alternatives?

Attached: i70 SpecSheet


texts: Can I replace a 2N222 by a BC558B, BC549C or BC327?

texts:
I just started studying Arduino and I'm watching a online course. I got into the stage where we're suppose to build some sort of protection system so we can plug-in outsourced power supply and prevent the arduino uno from frying.

My problem is that the class course uses a 2N222 Transistor and he talks about \$V_{ce}\$ and \$V_{be}\$ numbers. All I have is a BC558B, BC549C and BC327 transistors, which I've tried to understand the datasheet and one of them is negative, and none of them seems to have similar numbers to the 2N222. I'd like some input regarding the protection system:

Are any of the transistors in hand useful for it, or should I forget about the ones I have and go buy a 2N222?

Maybe I didn't understand much of the course. But the guy says that the Arduino can't handle more than 50 mA and if I want to turn on something that consumes more than that, I need an external power source. But if I plug the power source direct into the Arduino, it will fry. I need to build a protection system using Relé and a Transistor. But he uses the 2N2222 transistor and I don't have this one here. I want to know what's important on it to figure out if the ones I have is enough.


texts: Why does this switch go both to ground AND to the input pin?

texts:
Here is a really simple circuit, that I don't quite understand:
https://microcontrollerslab.com/wp-content/uploads/2019/03/Push-button-interfacing-with-ESP32.jpg
I understand the LED portion. What I am not certain I understand is the push button portion.
The voltage goes from the 3.3v pin to the switch, which then routes to both the GPIO15 pin as well as the ground.
Why does it go to both? Is that because the voltage could be too high for the pin and you want to avoid burning it out? If so, do you always need to do this, or is it just sometimes and how do you decide when? Also, why have the resistor after the branch to the GPIO 15 pin?
If it's helpful, here is the link to the actual tutorial that explains what this diagram is for:
https://microcontrollerslab.com/push-button-esp32-gpio-digital-input/
I'm adding a self-drawn diagram that may not be any good but I think this is how it should be represented.
Here is my code, written in the arduino IDE, which works exactly as I expect: when you push the button, the LED toggles its state.
I'm just curious about why the resistor-to-ground part by the GPIO15 pin is necessary.
const int LED_PIN = 22;
const int PUSH_BUTTON = 15;

int pushButtonState;
int ledState = LOW;

void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(PUSH_BUTTON, INPUT);
  digitalWrite(LED_PIN, ledState);
}

void loop() {
  int newButtonState = digitalRead(PUSH_BUTTON);

  if (pushButtonState == LOW && newButtonState == HIGH) {
    if (ledState == LOW) {
      ledState = HIGH;
    }
    else {
      ledState = LOW;
    }
    digitalWrite(LED_PIN, ledState);
  }

  pushButtonState = newButtonState;
}


texts: Convert a hall-effect flow meter to operate as on-off switch

texts:
I'd like to convert a hall-effect flow meter to operate as on-off switch.  the output is in pulses, which arrive at a rate proportional to the flow rate.  what I would like to do is have a circuit that would turn on and off like a conventional flow switch.  i.e., a circuit that you can tell: "if X pulse rate, turn switch on."

Thanks!
edit: what I'm thinking about is basically a delay on make timer with the interval set to some timing that would give me the toggle function.  e.g., we are getting 5 pulses per second, with the timer set to something just over 200ms, such that the on state is maintained as long as that many pulses continue to register.

but if it goes to 4 pulses, the frequency will be too low, and rejected by a Schmitt trigger or comparator.

There, I think I just told everyone how little I know. :)


texts: Automatically upload binary file to nucleo after compiling in Keil

texts:
I bought Nucleo F411RE and I'm using Keil uVision 5 as IDE for programming it. To download program to Nucleo, you simply copy it in the virtual nucleo drive:

Of course, I'd like to have this task automated. To do so, I tried to use the Keil project configuration:

But that doesn't work:

*** Error: CreateProcess failed, Command: 'copy build\Nucleo_blink_led_NUCLEO_F411RE.bin H:\'

So what should I do? Keil is recommended by Nucleo manufacturer, yet this simple issue seems to have no solution on the internet...


texts: Using voltage divider vs using a DC-DC converter

texts:
I have a DC-DC converter that with a Vin of 4.75V-14V and a Vout of 18V.
Unfortunately I have a Vsupply of 24V.
Should I use another DC-DC converter with a Vin capable of 24V and a Vout between 4.75V and 14V or should I just use a voltage divider to to step 24V down to an acceptable voltage.
Are there advantages or disadvantages for either?
Is there a problem with using too many DC-DC converters in series?


texts:
Let's say we have the following netlist

* Standard cell circuit

.global VDD VSS

.prot
    .lib '.\reference_models.lib' TT
.unprot

***********************************************************
.SUBCKT ZP_NAND2 QN A B
M1I1 N1N9 B VSS VSS N W=WN L=LN
M1I2 QN A N1N9 VSS N W=WN L=LN
M1I3 QN A VDD VDD P W=WP L=LP
M1I4 QN B VDD VDD P W=WP L=LP
.ENDS

.SUBCKT ZP_INV QN A
M1I1 QN A VDD VDD P W=WP L=LP
M1I2 QN A VSS VSS N W=WN L=LN
.ENDS

.SUBCKT AN2D1  Z A1 A2
X1I8 N1N1 A1 A2 ZP_NAND2 wp=1.62um lp=0.35um wn=1.07um ln=0.09um
X1I9 Z N1N1 ZP_INV wp=2.70um lp=0.35um wn=1.35um ln=0.09um

c1   Z   VSS 0.018pf
c2   A1  VSS 0.009pf
c3   A2  VSS 0.009pf
.ENDS
**************************************************************
X1  Z A1 A2 AN2D1
*************************

.param vdd = 1.8
.param vss =0

Vvdd VDD 0 VDD
Vvss VSS 0 VSS

Vin1 A1 0 pulse (vss vdd 2ns     200ps     200ps     3.8ns       8ns)
Vin2 A2 0 pulse (vdd vss 4ns     200ps     200ps     2ns         8ns)

.TRAN 1p 20n

.measure tran pow_avg_X1 avg p(X1)
*.measure tran pow_avg_mn avg p(X1.mn)
*.measure tran pow_avg_mp avg p(X1.mp)
*.measure tran total_power param='(pow_avg_mn+pow_avg_mp)'

.measure tran I_integ integ I(Vvdd)
.measure tran P_Iinteg param='I_integ*vdd/20n'

****************************************************
.meas tran TPHL trig v(A2) val='0.9' TD=0
+   fall=1 targ v(z) val='0.9' fall=1
.meas tran TPLH trig v(z) val='0.9' TD=0
+   rise=1 targ v(A1) val='0.9' rise=1
********************************************************

.end

When we run it in hspice, we get the following result for Tplh and Tphl

tphl=  1.1032E-10
tplh= -6.6974E-11

How do we make them equal(not necessarily 100% equal,, but lets give them a maximum difference of only 3%)? The only thing that we can vary is the transistor's width (we need to make the 'L' fixed to 90 nm). Aside from randomly guessing the value of 'W' to make them equal, are there any methodologies out there to follow?

Thanks


texts: What means coil inductance (h) for relays?

texts:
I'm looking at the data-sheet for a Single Coil Latched Relay. In there, i see the Coil Inductance (ref. value)(H) for Armature ON and OFF column.

Specs:

Rated Voltage: 3 (VDC)
Rated Current: 67 (mA)
Coil Resistance: 45 Ohm
Armature ON: 0.09 (H)
Armature OFF: 0.06 (H)

Since it mentioned for switching on and off the armature, it got me curious.

Could somebody explain what these numbers (0.09 and 0.06) mean? And how you would use this?


texts: Why is impulse response of LTI system important

texts: Why is the impulse response for a LTI system also called its system response? What is special about the output when the input is impulse signal? I understand that impulse signal contains all the frequencies from zero to infinity and also the response for any input is convolution with the impulse response but how is the system nature or system parameters concluded by observing the response of the system due to impulse input.


texts: Electrical equivalence and Difference between Flux and Torque in AC motors

texts: For AC motors, Synchronous and Asynchronous ones, are these two linked together or different quantities, namely magnetic flux and torque? Also if I want to measure these quantities electrically then what are their electrical equivalents?


texts: Converting 28VDC -> 14VDC at around 200A How do you pull that off with that kind of current?

texts:
Current boat has 110AC air conditioners and some small appliances but the rest of the systems are on 12VDC.  Genset ate a jellyfish and has to be replaced, so I'm working out options to upgrade/change the electrical system.  Converting the whole boat to 24VDC is probably not doable as that seriously limits the places you can get replacement parts.

I've found a DC Generator with a ~200Amp output @ 28VDC that I need to convert down to 14VDC to charge the house batteries.

How do you do that efficiently at such high amperage?  Lots of parts out there, but they are typically 5A or less and running them in parallel is just not a very good idea.

Rest of the boat is on 12V as well, trying to use 24VDC to halve the current from the Genset to the battery bank and power panel.

Wondering aloud if it makes more sense to go with alternator instead of a Generator and convert from AC -> DC closer to the battery bank as that would cut the current flow for the longest part of the wire by 6-10x.  The problem with AC is the speed of the engine affects the 60Hz portion of the equation.  I've considered adding one alternator per Diesel but can't figure out how to make that work since the RPMs of the engines that run the props are subject to change based upon propulsion needs and getting reliable 60Hz out of that setup seems nearly impossible.  And combining the 2 AC alternators when the motor speeds can't be synced seems like inviting disaster.

Any ideas how to solve this kind of problem without just replacing the existing generator with another?

============  Answers to some questions in the coments/answers =======

Old genset was 6500Watts @ 110VAC
200 Amps @ 28VDC to provide about 400 Amps @ 12VDC  which is only 4800 Watts but sufficient for the aircon load
With a fully DC system, I'd be feeding a larger Inverter to run the Aircon from the generated DC or the batteries.


texts:
What would be the consequences of using a charger that targets 4.3V to charge a 4.2V Li-Po battery?

Will the battery be damaged? In what way?


texts:
I am working on the project which involves running a DC motor which is used to raise/lower window glass in the vehicle.

While running, motor draws about 1.5A of current. However, when the window reaches the end of the sliders and the motor can no longer raise/lower the glass, it starts drawing up to 15A until you release the button.

I want to use AVR microcontroller to control this motor and would like to stop the motor when the window reaches the barrier. I managed to come up with three solutions thus far:

Use switches which will trigger and inform microcontroller when the window reaches the barrier. I'd like to avoid this because this means installing two switches per window and running extra cables to the microcontroller.
Use timer function which will turn off the motor after a specific amount of time. This is not applicable because the voltage may vary and the motor might turn faster or slower than normal. Also, the window might be in an unknown position when starting the timer (all the way up, in the middle...).
Use some kind of high current detector and route it to microcontroller's input, alerting the program when the current threshold is reached (say 5A). Something like a transistor, relay or similar device which can handle the current this high on the input.

I am pretty much a beginner when it comes to electronics, so I was thinking if there is a way to detect this high current (motor is running on ~12V) and provide this signal to microcontroller (which is running on 5V).

I'll appreciate any help. Thanks!


texts:
Currently, I have a software which able to read voltage, current, active power, apparent power and reactive power from appliances which I assume the readings should be approximately same even though I have changed the venue for setup the same appliances. But after I have moved the same setup to a different floor or a different power source, I encounter the issue of readings have apparently run out of the range from my previous reading.

Is there any cause that can make such changes?

Edit:

The previous reading I get is :

Voltage:240.2
Current:    9.9
Real Power: 1.818
Apparent Power: 1.7003081
Reactive Power: 1.589
Power Factor:   0.7721

After setup changed to the different place with the same appliance setup:

Voltage:240.1
Current:    11.1Real Power:   1.817Apparent Power:  1.965097Reactive Power:   2.0375Power Factor:   0.66605


texts: Assembling PCB - C and R holes are touching

texts: Silly question. I am assembling a PCB. The holes for R3 and C29 (center right) are touching each other. Is this correct?


texts: Can I use a 30kVA 3-phase 480V delta to 208V/120V wye as a 208V input and 420V output? This is to be used to run a motor for a hydraulic system.


texts:
I was soldering wires to 18650 batteries, and while I was soldering the + tip at one of them, it suddenly became very hot. I thought that maybe some drip of tin get under the tip and shorted it, so I took voltmeter and it measured no voltage, so the cell must be shorted. As it was getting hot and I wasn't able to find any drip of tin which shorted it, I just throwed the cell into iron bucket filled with water.

Is this what I should do? Or what am I supposed to do if this will happend again?
Thanks


texts: How to make a picaxe service remote for a pioneer ir controller for a DVR - 660H and DVP 540H DVD recorder


texts:
I have an elementary question about current flow:

If I connect a simple 1.5 V battery to a hypothetical LED of 1.5 ohm and an ideal ammeter, the ammeter would show a current of 1 Ampere and the LED would glow (let us assume the power is enough).

Now, instead if:

---------- 1.5 ohm LED ----- ideal ammeter ----- Ground
------- free

That is, The positive terminal of the 1.5 V battery connects to one end of the LED, and the other end of the LED to the ideal ammeter which in turn goes to a thick copper wire connected to ground, then the LED will not glow and the ammeter will read zero, since the negative end of the battery is free. (Yes ?)

But if it is this:

---------- LED ----- ideal ammeter 1 ----- Ground
------- ideal ammeter 2 ---- ground

then I assume the LED will glow, the ideal ammeter 1 will show a current of 1 Ampere. What about ideal ammeter 2 ? Doesn't it also read 1 ampere ?

The reason I am asking is because I am trying to understand the principle of ground fault circuit interrupters, but then I got confused about the basic scenario above. So in a ground fault circuit interrupter, if there is a path to ground through a person touching a live wire, then there is a current difference between the return path and the forward path that triggers the interrupter... but if the negative end is also connected to ground (through the person or by being earthed), shouldn't the return path have the same current ?

Thanks !


texts: How to verify if power supply is enough to handle power consumption spike?

texts:
I am looking to find out how to analyze what will happen to a power supply if my load suddenly draws more current. On my current example ( but that also happen to me with different components ) For example, the power supply is 5 V with 2.4 A, what if I over draw the current?

How do I calculate the voltage drop on a power supply if I draw X amount of current more than what the supply can handle for Y seconds?


texts: Soil moisture using a capacitive sensor - can cheap version of it contaminate soil

texts:
Maybe a bit silly question but I was wondering if these cheap versions of soil moisture capacitive sensor (Corrosion Resistant Analog Capacitive Soil Moisture Sensor) may release chemicals to soil.

Not sure if there is any FDA approved version of such a sensor.


texts: How to raise capacitor voltage to use a capacitor bank as a battery?

texts:
This is a highly theoretical question.
There are these 100kF, 2.7V capacitors you can buy online. According to my calculations, 5 of them in series would give me the energy capacity close to a 44Ah, 12V car battery (about 0.5kWh), which is convenient, because the voltage rating of the arrangement would be 13.5V.
So, in theory, I could replace my car battery with a capacitor bank that costs 10x more. The problem is that the output voltage is linear to the charge, so the voltage would have to vary from, say 3V (not lower to keep the current manageable) to 13.5V, which is well outside the operating range for car's stuff.
The questions:

What kind of circuit/equipment I would need to stabilize [3V-13.5V] to 12V?
What would be the efficiency of the process for the high currents needed for a car?


texts: Noise when powering headphones amplifier through USB port

texts:
This question is actually connected with this one:
Getting 1.2V from USB

I've successfully connected my FIIO E3 headphones amplifier to USB (so that I don't have to use batteries). But I've notices few things:

1) I connect it to computer USB port. I get some strange noise - like humming and crackling. Actually, when I do something on my computer (e.g. I copy something to HDD), that noise gets louder.

2) If I connect it to the computer USB port with USB extension cord, I don't hear noise from 1), but I hear very loud white noise

3) Then I've tried to connect it to my iPhone charger (it gives 5V from 220V). It works perfectly (no humming or other noise).

So anyone got a clue what's happening ?

Thanks :)


texts: Why do RC circuit voltages decay *slowly* rather than instantly?

texts:
Let's take the simplest RC circuit imaginable:

simulate this circuit – Schematic created using CircuitLab

Now I think I properly understand why the voltage rises slowly after the leading edge of a pulse--the capacitor acts like a variable-resistor turning the circuit into a voltage divider. R1 delays the time it takes to charge the capacitor, and while it accumulates charge, its resistance slowly increases, changing the balance in the voltage divider to increase the voltage to OUT.

However, I don't understand why, in a situation where OUT is presumably much lower-impedance than R1 (e.g. OUT's a short), when the clock goes low the cap doesn't dump all its charge through OUT as fast as it could with a short. I understand that OUT is not usually a short and so does actually have some resistance, which means the charge has to flow out of the cap somewhat slower and is divided proportionally between R1 and OUT's load. But does this non-trivial resistance of OUT really account for all or even a significant portion of how slow the voltage decays? Or am I not considering some other effect?


texts:
I'm working on a couple of solar panel projects here is the list of question I have.

1)  I"m looking for a wire chart that shows how far you can run a specific gauge wire at 12vdc before there is significant voltage loss.

2)  I have 18/4 cable, what gauge is the wire if i twist two of the conductors together?

3)  I have a 35w solar panel how long does it take to generate one amp hour of power?

4)  Lets say i have a 1 amp draw on a 65ah deep cycle battery and the draw is continuous for 10 hours (dusk till dawn) how may amps have i used?

5)  Most boats have 2 battery banks. One house battery (for electric appliances) and one reserved battery to start the boat motor. I want to solar charge both batteries then disconnect the reserve battery so there is no load on it while i use the house battery. The solar charge monitor i have only has one battery terminal. I tried to wire the coil of a relay across the solar input terminal so that when there was sunlight the relay would close the circuit on the reserve battery so it could be charged but the coil took to much power there was not charge output the solar panel is only 10w. Where can i find a low current relay or what is a better method?

6) I'm setting up solar powered motion detector led lights but i can't put them in the sunlight and have them where that need to be....I want to set up a remote solar powered battery charging station then run wire to the motion detector led lights. another problem is that they are lower than 12vdc. Its simple enough to by pass the solar panel input then connect my own power supply. What is the most efficient way to drop the voltage to 6vdc step down transformer or resistor? is there an adjustable step down transformer?

7) I bought automotive 12vdc led lights they work great i could also set them up as motion detector led lights where can i get a 12vdc outdoor motion detector and a day/night photo electric switch?

8) last problem the solar panel i bought didn't come with mouthing brackets. I want to mount it on 2x4 then sit it on the ground but i need to adjust it to the correct angle toward the sun. Where can i get or make an adjustable bracket?


texts: How to fix ngspice simulation of Cree XLAMP CXB1507

texts:
I'm trying to simulate the 36V Cree XLAMP CXB1507 (spice model) using kicad+ngspice.
When I try simulate it gives the following error:

.model cxb1507 36v d is=6.15257e-19 n=32.22321 rs=9.82504 xti=1282.00581 ...
Unknown model type 36v - ignored

If I delete the 36v in the spice model the simulation runs, but I'm not sure if it's accurate.
Aplologies if this is simple/obvious, I'm new to circuit simulation.


texts:
Designing a modbus master using a STM32F030CCT6 and a SN75HVD10 (3.3V).

This is the schematic

When i send the following message from the UART:
01 03 00 00 00 06 c5 c8

I see the following scopes (top is A, and the bottom is B).

However when sending the same message using a Raspberry PI (5V) and a RS-485 converter cable the following scopes can be seen:

As you can see, the channels here are reversed. Whats on A using SN75HVD10 is on B using RPi. So i thought to myself, ok, lets switch the cables. But then the microcontroller stops responding and no traces can be seen on the scope.

What can be done do change the "channels".
Also, why is not the signal going down to 0V?


texts:
I'm using a program called Logisism and it has in-built features such as a D flip-flop:

However it doesn't show how it's actually made out of logic gates. Can someone please show me a diagram of have it is made. I've done some searching by get completely different results.

Thanks


texts: Why would a whole region have severe difficulties with the railway "signalling system"?

texts:
The background for my question is that Oslo Central Station, Norway's main railway station, and the surrounding area keeps getting closed because of "signalling errors".

The railway authority always simplify their explanations like this:

  There is a complete stoppage of all trains on Oslo S (central station) due to signal
  problems. The railway authority is working to correct the error. Delays
  will unfortunately occur.

The main newspaper in Oslo, Aftenposten, in the most recent case added some information by saying it was a "ground error" causing the shut down.

Now, the vagueness intrigues me and I would really like to know if any of you have theories on what the cause of this would be, or experience working with railway systems.

What could be the cause of the multiple massive shut downs of railway traffic in the Oslo area?


texts: RPi pin not controlling NPN transistor as expected

texts:
I'm using a Raspberry Pi to control an ESC and would like to be able to turn it on and off at will using a TIP3055 NPN transistor.

I've hooked everything up as diagrammed below. The 11 V battery runs through a distribution board that provides several 11 V lines and a regulated 5 V line which will power the RPi in the future. As for now, it's powered via a separate USB connection.

If I manually disconnect and reconnect the wire to GPIO20, the transistor works as expected. If I leave the wire connect and turn the pin on and off with software, the ESC maintains power the entire time. I thought maybe power was being forced from the transistor to the GPIO pin (as the wire reads ~2 V when connected) so I put a diode between the resistor and the pin but that had no effect.

At this point I'm fairly certain that I shouldn't have used this particular transistor. I believe I should have put in a MOSFET but I wasn't clear on what I was doing when I started.

Aside from "mostly everything" what do I not know that is not letting me set this up correctly?


texts: Convert 24 V to 20 mA (none is variable)

texts:
I have a PLC (take the "P" with a pinch of salt), it has some analogue inputs (4-20 mA) that I need to use to detect if 24 V is present or not.
I can program the logic to say above X mA 24 V must be present, below X mA it mustn't be present (the reason is I have some controllable relay outputs, but there is no feedback to say which state it is in and the only spare inputs are analogue). Is it simply a case of I = V/R, so on the analogue input common I stick 0 V DC and on the input I put a 1200 Ohm resistor and the 24 V DC into that. My logic could then be if >10 mA 24 V must be present, <10 mA it isn't?


texts: Circle with arrow symbol interpretation in circuit

texts:
I am trying to find all currents in this circuit:

(Question 19 from https://www.allaboutcircuits.com/worksheets/algebraic-equation-manipulation-for-electric-circuits/)
Although I'm familiar with Ohm's law and can find values in series-parallel circuits, I don't know how to approach this.
What is the meaning of the circle with arrow in it symbol, that has 5mA?
Should I interpret that as an extra power source? Why not use a battery symbol there then?
What is the approach to solve this problem?


texts:
For the part of the circuit of sinusoidal circuit given below, the following data is given (effective values): $$E=10V,I_g=2\sqrt 3 A,I_2=2A.$$

Impedance of conductor is $$Z_C=5\Omega.$$

Current Ig is leading in phase with regards to E for 2pi/3, and E is running late in phase with regards to I2 for pi/2.

Evaluate effective value of voltage U10.

I think that the following intuitive solution is completely incorrect:

By using potential of nodes method on branch 1-0, if we set 0 node as referent, we have:
$$\underline{V_1}\frac{1}{\underline{Z_C}}=\frac{\underline{E}}{\underline{Z_C}}\Rightarrow \underline{V_1}=\underline{E}$$

Could someone explain why this solution is incorrect?

What is a correct approach?


texts: Sensored BLDC Motor from Hoverboard - Protect driver?

texts:
I'm designing a controller and Arduino library for a brushless DC motor, which was used in a Hoverboard. Its specs are 36V, 200W. I use the standard circuit that is suggested everywhere on the internet (only showoing the power electronics, not the Hall sensors):

Here, VCC is 15V, and the +24V pin is currently also set to VCC (They are sourced from the same power supply).

I have added a cascade of LEDs to the 3 half-bridges to see, where the current flows through the coils of the motor. As the driver, I use IRS2183, as the MOSFETS, I use N-channel IRFZ48N, which should easily manage the load.

I experience the following problem: I control the motor with PWM (input in the correct order into Lin and Hin of the drivers) and it spins nicely. Sometimes, it happens that the motor abruptly stops or shortly blocks and then proceeds rotation. I believe this is due to some bug in my control software. In roughly 50% of these cases, one of the drivers burns (i.e. it becomes hot, and it wont work anymore, I have to exchange it). They do not become hot during normal operation.

My questions:

Is it from the above circuit possible, that the drivers burn because of the motor, or is it my particular setup of the schematic (built on a breadboard)
What can I do to protect the drivers from burning, when the motor apruptly stops or otherwise induces high voltage into the FETs?
Is it harmful, when I run the motor with 15V, instead of its 36V nominal voltage?


texts: Why rising_edge is only used to detect clock input?

texts:
In VHDL rising_edge is used to detect signal transition from logic zero to logic one. In almost every vhdl sample codes that I referred rising_edge is only used to detect logic zero to logic one transition of clock input.

Why it is recommended only for reference clock? Why can't we used this syntax to check logic zero to logic one transition of any other input or  signals inside the program?


texts: Circuit operation and component substitution questions for stroboscopic timing light

texts:
I'm trying to make a piece of circuitry, for a tool used to set the ignition timing of my old car.

I've found the schematic and description here:

http://citroen.tramontana.co.hu/en/ignition/stroboscopic-timing-light

Do you think it is working properly?

But I made some changes and I don't know if it is OK:

I used a Nichia NFSL757GT LED, and I've regulated the current with two 220 ohm resistors in parallel. Is it OK?
Instead of the BD135 BJT, I've used a FZT651. Is it OK?
I can't understand the purpose of R1, D2 and C1. The author wrote that they protect the thyristor, but what does it mean? R1 and D2 are needed to regulate the voltage? And C1?
is C1 a 220nF capacitor?

Thanks.


texts: switch between battery and usb power no microcontroller circuit

texts:
Following an earlier question about how to switch between battery and USB power,

I would love to implement the TC2014 LDO as suggested by Russell McMahon.

That way I could switch between 4AA batteries (1.2V*4 or 1.5V*4) and USB power. The battery voltage would nicely be regulated to 5V too. And the idea was to use the shutdown pin of the chip IF USB power is detected. The device also has to work when no batteries are present.

I am not too experienced with this, but I thought to connect the 5V from the USB to the SHUTDOWN pin from the LDO chip. Pitywise, the pin function is inverted, if SHUTDOWN is low, Vout from the LDO chip is low.
I am now considering using an XOR gate to make the thing work:

simulate this circuit – Schematic created using CircuitLab

I would love to limit the amount of components, but the number of diodes is already high, and the whole thing feels a bit crafted

My questions:

Is there a better suitable chip (with an inverted shutdown pin)
is there a better circuit (without voltage drop) to get this (I would prefer to get rid of D1, but then, the XOR has no desired operation)


texts:
I am new here and a newbie regarding electronics, I shoot PCP air rifles and have a small project regarding the air rifle. The shooting mechanism is consisted of a trigger releasing a spring loaded hammer to open the air valve with 110~130 bar of pressure behind it. The hammer is tensioned with the spring. The idea is to replace the mechanical trigger (hammer) with a solenoid and variable power output. I was thinking of using a solenoid with capacitor discharge circuit and a 555 timer. The solenoid will be powered for a fractions of a second to hit open the valve, I was thinking of 2 ways to do this:

Limit the charge voltage to be discharged to the solenoid to have variable power
Play with the time the solenoid is powered.

I need to have the variable power to control the speed of the PCP.


texts: What is causing the DC Offset in Mirrored Howland Current Pump Circuit

texts:
I am creating a current source to try to expand my knowledge about electronics design. After some research I decided to build the Howland setup since I want to develop a bipolar current source. The circuit is shown below:

I have created a breadboarded setup of this circuit, and the voltage signals I measure at Vload1 and Vload2 have a DC offset of approximately 1.5V and 2.3V respectively. I have tried varying the frequency between 10kHz and 100kHz, as well as varying the load between 500-4000 ohms. The offset voltages varied by a few hundred mV during these tests. I am wondering if anyone may know what could be causing the DC offset?
Notes:

When I simulated this circuit in LTSpice there is no DC offset. In my first simulations I got the "Singular Matrix" error, at which point I added ".options gshunt 1e-16". I realize this connects the nodes to ground via a shunt conductance, so I have also tried ".options gfloat=0", but this didn't result in any offset occurring.
I have tested the physical circuit with only one current source driving a grounded load, and no offset occurs (which is expected).


texts: Arduino and N mosfet lithium battery charging/discharging measuring capacity

texts:
I need an Arduino based lithium battery tester that uses N channel Mosfets to switch On charging from and external power source and discharging through a 2 Ohm resistor. I have no issues with either charging or discharging circuit schematic, however i can not combine them together. I'm attaching the schematic for discharging the battery into the 2 Ohm resistor, please help with adding the components for making it able to charge the battery from an external, let's say 4.2V power source, all controlled by Arduino.

I also need to have a state when i'm Not charging or discharging so i guess for that purpose i need to use Pin 11 on Arduino


texts: How to find current through series of potentiometers, and if it is safe for potentiometers? (Arduino)

texts:
I have 9 potentiometer with the specs: 10k Ohms and 0.5W

I'm using an Arduino Mega, and using it's 5V port output to power these potentiometers in series, and I saw online that the max current this board can supply is ~450 mA

So, if there are 9 10k Ohm resistors in series, the total resistance in the circuit is 90k Ohms. So, using ohms law I=V/R = 5/90000 = 0.0556 mA current will flow through the potentiometers?

And to find the maximum current each potentiometer can take, if I use I = sqrt(P/R) = sqrt(0.5/10000) = 7.07 mA.

So since only 0.0556 mA will flow through these potentiometers and each potentiometer can take up to a maximum of 7.07 mA (before overheating?), is this circuit totally perfect and all my calculations are correct?


texts: How to drop the voltage from 3.8V to 3.3V - LDO or Schottky diode?

texts:
What is the better way of dropping the voltage from 3.8V do 3.3V - using an LDO (e.g LP2985IM5-3.3) or the Schottky diode? It's about power supply for a microcontroller.
I plan to use the ST1S10PHR step-down from 12V to 3.8V to power the GSM radio while I need 3.3V to power the MSP430 mcu. The input of the LDO or the Schottky would be the Vout of the ST1S10PHR step-down.

The problem I see with the Schottky diode is that the Vforward is a function of Iforward and this dependency is quite significant (e.g. for BAS70H: If=1mA -> Vf=410mV; If=15mA -> Vf=1V).

For the LDO LP2985IM5-3.3 I haven't found any particular limitation, however I met some chip that required the Vin to be Vout+1.5V. That is impossible in my case.


texts: Likely consequences of slightly exceeding 500mA USB current

texts:
As we know, a USB 2.0 device, once it has properly negotiated with the host, is allowed to draw 500mA.

Suppose that you are designing such a device, and your input current limiter chip is tuned by a resistor.  Let's say that the resistors available to you are ±1% tolerance.

Should you size your resistor to draw 500mA in the nominal case, knowing that in the maximum case you will draw 505mA?  Or should you size your resistor to draw 495mA, so that you are guaranteed to respect the exact limit, but less power is available to your device?


texts: Driving P-Channel MOSFET from MCU Pin While Running on Coin Battery

texts:
I made a circuit that uses the DMP2305U P-Channel enhancement mode MOSFET.  I connected the pin of the PIC microcontroller directly to the gate pin of the MOSFET.  The purpose of this MOSFET to enable the power rail that an Xbee is connected to.  I'm running the whole board off of a CR2477 lithium battery or external power with a TPS63001 buck/boost.  The problem I'm running into is the CR2477 cannot run the Xbee, the PIC starts browning out and things just stop working.  If I connect two AAs to the battery terminals, the board runs fine.  From external power it runs just as fine.  I can enable and disable the MOSFET by manipulating the pin on the PIC.

I believe the problem I'm running into is the buck/boost is providing 3.3V and the DMP2305U has a -0.7V drop which means there's not high enough voltage to run the Xbee which requires a minimum of 2.8V.

Assuming it's okay to run the MOSFET directly from the microcontroller, why might I have an issue running from CR2477 but not 2xAAs?

A friend pointed me to this write-up:  Using MOSFETs in Load Switch Applications (AND9093 by On Semiconductor)

This tells me I need a transistor in front of the MOSFET.  My success on external power and 2xAAs tells me I don't, that the 25mA I can source from the PIC pin is enough.  Even if I put a transistor in front of it, I'd still have a voltage drop across the MOSFET, right?


texts: Can I differentiate between a UPS, Generator and Main sine wave using a micro-controller?

texts:
Are there any distinguishing features of a mains power supply that will allow me to tell the difference between mains power supplied by

the utility company,
a generator, or
a UPS?

How can I use a microcontroller to make this determination?


texts: Coupled Inductor for DC-DC Converter ~50W

texts:
I'm designing a DC-DC Flyback or SEPIC converter, not decided yet.
The converter is used to source some power LED's.
The output voltage up to 60V and 1A with an input of 12-24V.
The switching frequency should be between 100kHz and 1MHz, because of the switching losses, we are considering a rather low frequency.
So I just had a glance what type of coupled inductors may be avaiable on the market.
I looked first for an inductor with ~40uH series inductance at a current raiting above 5A and an even higher satturation current.
But I could just find some rather strange products, looking like ment for a rather specific application.
Are there other more common terms than "coupled inductor" to find such products? Also manufacturer names would be helpful.
I know a transformer may met my conditions, but are transformers not by general ment to transform energy rather than store it?


texts: USB connection random issues after installing a 220VAC ventilator

texts:
We're building a machine whith an USB device connected to a PC, all working fine. After some heat issues we added some 220VAC (Europe) ventilators and we started having random USB issues. Probably the 220VAC wires to these ventilators are radiating electrical noise, my question is, should I place a mains filter near the ventilator and avoid the antenna effect or just place them near the 220VAC external connector?
EDIT:
The USB cable is 5 meter long. The 220VAC wires to the ventilator are about 4 meter long.
Here is a simple diagram:


texts: Are the 2 terminals of an incandescent bulb lamp equivalent?

texts: Compared to a resistor, which has 2 equivalent terminals, does an incandescent bulb lamp also have equivalent terminals?


texts: Why it is preferred to have local oscillator frequency larger than carrier frequency in superheterodyne receiver?

texts:
So to obtain intermediate frequency  Fif, why it is preferred to use Flo > fc

So we use this equation

Fif = Flo - Fc

Instead of

Fif = Fc - Flo


texts: Question about bi-directional pin from Roth reference

texts:
I now am studying the tri-state buffer from the reference "Fundamental of Logic Design", 6th edition, By: C. H. Roth and L. L. Kinney.
I found that circuit of a bi-directional pin as application of tri-state buffer:

With this text descriping it

  Integrated circuits are often designed using bi-directional pins for
  input and output. Bi-directional means that the same pin can be used
  as an input pin and as an output pin, but not both at the same time.
  To accomplish this, the circuit output is connected to the pin through
  a three-state buffer, as shown in Figure 9-12.When the buffer is
  enabled, the pin is driven with the output signal.When the buffer is
  disabled, an external source can drive the input pin.

I have some questions about this circuit:

In case of EN=1, the output of the ciruit will be put in the bi-directional bin and also looped again into the circuit. I think there should be some other tri-state buffer in the lower signal to prevent this. Is this right?
In case of EN=1, what if there is some logic value is put on the bi-directional pin as an input from external source? This will result in unknown state I think. So I think there should be another tri-state buffer on the line between the join and the pin. Is this right?


texts: Using a CFL ballast to power 9W UV tubes

texts:
I would like to build a low-cost home UV exposure box for PCB manufacturing. Recently my attention was brought to these dirt cheap UV bulbs which are used in manicure drying lamps. I have the ballast of a 32W CFL tube which I would like to use for the task. I have a couple of questions:

How many tubes should I use with the 32W ballast?
How should I wire the tubes? I'm guessing in series, since the ballast is supposed to be a constant-current source; am I right?
The ballast has 4 electrodes, but the UV tubes have only 2. I'm guessing it's because the electrodes in the UV tubes don't have to be heated. What should I do with the extra wires? Short them like this? Won't it melt the heating circuitry then?
Will this expose the PCB adequately?


texts:
I'm using a PCM5122 and previously a PCM5102 (this is the same part, but without the I2C/SPI interface) in my design and I've had a couple of prototypes end up with the 3.3v rail shorted to ground. A little investigation has yielded that the CPVDD (Charge Pump) pin is bringing the rail near ground. Similarly, the VNEG pin has only 20k ohm resistance to ground. No other pins appear to be shorted. The outputs of the DAC connect directly to an onboard amp, as well as being tee'd off into a vehicle amplifier.

My question is this: What could cause this kind of damage to the DAC and what can I do to prevent it? I have not done anything outside the box with the implementation, other than change the output filter to supply a higher output load.

Here is my schematic:

Here's my PCB layout:


texts:
simulate this circuit – Schematic created using CircuitLab

I have to calculate the energy of the inductors magnetic field at t = 6 ms.

I am given: E = 50 V, R1 = 10 Ω, R2 = 15 Ω, R3 = 20 Ω and L = 0.1 H

So at t < 0, the switch is closed and the current is flowing. In the parallel section, we get I1 and I2, since the inductor formula is time-dependent and it is t < 0 the inductor will have no voltage and will behave like a wire.

I calculate the total resistance in the parallel and add R3 for Rtotal;

$$ R_{total} = (\frac{1}{R_1} + \frac{1}{R_2})^{-1} + R_3 = 26 Ω $$

$$ I = \frac{U}{R_{total}} = \frac{50}{26} = 1.92 A $$

Now I can calculate the voltages in the circuit parts;

$$ U_{R3} = I * R_3 = 1.92 * 20 = 38.40 V $$

The voltage in parallel should be the same so UR1 = UR2 and together with UR3 should amount to 50 V, 50 - 38.40 = 11.60V in parallel.

At t = 0 the switch is open. The current stops flowing from the source and the depletion of the inductor starts.

It is a falling function the only voltage provider is the inductor;

$$ I = \frac{U_L}{R_1 + R_2} \rightarrow 1.92 = \frac{U_L}{25} \rightarrow U_L = 48 V $$

So since it is t = 0 things will remain the same;

$$ I_L = 1.92 \exp{\frac{-0}{\tau}} = 1.92 A $$

$$ U_L = 48 \exp{\frac{-0}{\tau}} = 48 V $$

At t = 6ms = 0.006 s;

$$ \tau = \frac{L}{R_{total}} = \frac{0.1}{25} = 0.004 $$

$$ I_L = 1.92\exp{\frac{-0.006}{0.004}} = 0.42 A $$

$$ U_L = 48\exp{\frac{-0.006}{0.004}} = 10.71 V $$

The energy of the inductor at t = 6 ms;

$$ W_L = \frac{Li^2}{2} = \frac{0.1 * 0.42^2}{2} = 0.008 J $$


texts:
I want to make a USBasp programmer for myself. I have the schematic. But they used a 10 pin ISP connector, whereas I want to use a 40 pin ZIF socket. How do I change the circuit for this purpose?

I've been using a circuit made on breadboard to load my .hex files, but I use 6 pin ISP. I don't quite understand the functions of the 10 pin ISP. What does the pins do?


texts: Input voltage on differential ADC (MCP33131D-05-E/MS)

texts:
I am evaluating a 16bit ADC (MCP33131D-05-E/MS) for my project. I want to sample in fully differential mode, but I have doubts as to what voltages are allowed on the Ain+ and Ain-.

Signal conditioning prior to the ADC is done with a dual supply so the voltage swing of the sampled signal will be -5V to +5V.

The datasheet states (on page 1 -> Features) that the ADC has a differential input -VREF to +VREF. This would make it -5V to +5V in my design since I will use a 5V voltage reference.

But then in the absolute maximum ratings it states the following:

Analog inputs w.r.t GND .............. .......... –0.3V to VREF+0.3V

I The question is: can I apply a negative (-VREF) signal to the Ain- or will the magic smoke escape?

Link to the datasheet of MCP33131D-05-E/MS


texts: Minimal hardware requirements ESP32 WROOM

texts:
I've had a very simple PCB designed to supply the ESP32 WROOM module with power using a voltage regulator that supplies it with 3.3V.

However, this does not seem to be enough to run the firmware application I loaded to it before hand.

Reading from the docs It tells me GPIO 0 should be high by default when not connected (which it is not.) However when I measure it is at 1.4V (floating)

What am I missing?


texts:
I am trying to count a square wave on a Raspberry PI.

I tried a variety of approaches:
http://abyz.co.uk/rpi/pigpio/examples.html  (Freq counter 1 and 2)
http://www.dnacoil.com/tools/measuring-light-intensity-with-the-tsl-235-and-a-raspberry-pi/#comment-2850

Both approaches seem to top out around a frequency of 300 which is not useful for direct light conditions .(Ok for low light.)

Data sheet of sensor: TSL235

Is there a better method for getting a square wave, 50% duty cycle on the PI


texts:
Is it possible to identify looking at the schematics whether a GPIO pin is configured as Input or Output pin for the case in following image?

PIN93 and PIN94 of a MCU are connected directly with connector J2 pins. It looks to me that these pins are in INPUT mode due to the capacitors on these pins. What are the chances that this is the other way round?


texts: what is the most difficult part of creating a DDR2 or DDR3 memory controller inside an FPGA?

texts:
In this day and age we can just use the memory IP provided to us by the FPGA vendor be it a soft IP or hard IP. This makes it almost trivial to communicate with high speed memory devices like DDR2 and DDR3 RAMs from the FPGA side. The PCB layout is still a massive challenge though and there is no doubt about this at all.
Many years ago I read that once upon a time, the engineers had to design a memory controller for high speed RAMs themself for an FPGA being used in their design. I am not sure how often this happened. I remember reading that at that time, the most difficult part of the memory controller design was the PHY.
From memory I can remember that it gave a reason as well. The reason it gave is that the PHY required very precise control of propagation delays and this required some sort of novel idea to be achieved in FPGA that has this issue with a nondeterministic propagation delay between different cells every time we compile the design.
Is this true? If this is true, how was this problem solved? I have never found details of this anywhere but I am curious to know what special steps engineers took to solve such a problem. It seems that they had to specify very tight timing constraints for specific paths and let the fitter do the rest, but if all it took was some SDC constraints, that does not appear too difficult to me in theory.


texts: How to spot different electronic devices?

texts: Recently my university has changed traditional counter meters into intelligent ones where they cut the power for illegal devices. At first as the rules say, the illegal ones are those with power usage over 1kW but surprisingly it allows those devices to be used but it cuts power for rice cookers with as less as 400W power usage. My question is that if there is any trick that they used to detect rice cookers? And if so, how to bypass it? Does it have anything with current detection?


texts:
I cannot get the CH2 working for PWM. It is set as CH1 and CH2N. CH1 is working without problems.
Below is the code I use to start the channels:
HAL_TIM_PWM_Start(&htim1,TIM_CHANNEL_1);
HAL_TIMEx_PWMN_Start(&htim1,TIM_CHANNEL_2);

while (1)
{
  TIM1->CCR1 = 1000;
}

Thank you for your help.


texts: what to do with the tab on the voltage regulator

texts:
I want to use the Lt3080 voltage(SOT223) There is also an tab on the voltage regulator. I found it is the same is Vout pin. I am thinking of using the pin to connect it to something else.

But what do i need to do with the Tab pin?
Ground it? Connect with Vout pin? nothing?


texts: Two conductors in a magnetic field, canceling each other's EMF?

texts:
If two conductors are in a changing magnetic field, oriented the same in the field, and they induced equal EMF's, can their wiring be oriented in a way that they can cancel each other's induced EMF?

So that that $$\epsilon_t= \epsilon_1 - \epsilon_2$$

Similar to twisted pair concept.


texts: LED dimming and modulating with two PWM signals

texts:
I have a need for an LED, driven by a constant current source, that can be smoothly dimmed and also semi-rapidly (say 2.5kHz) modulated for later bandpass filtering. I've designed a possible circuit, given below. The constant current source and PWM-dimming were already familiar to me but I seem to have found the switching solution through beginner's luck.

The circuit seems to work well in Spice and on a breadboard. Is there a compelling reason to edit or reject this circuit for the given purpose? Also, could someone help me understand how the switching via Q2 works?

Thanks