texts: What is state of port B when port A of FT2232H is in sync. FT245 mode?

texts:
I am designing Spartan 6 dev board with FT2232H interface, and I would like to use FT2232H to program  AT45 flash with bitstream and then switch FTDI to FT245 mode and use 60MHz clock of 2232H as main clock of Spartan.

As far as programming AT45 flash I got it covered, I will hold Spartan in High-Z by holding Spartan's PROGRAM_B low with FT2232H (which should be possible by using GPIO pins of port B in SPI mode).

Then I would release PROGRAM_B to high (I have 4.7k pull-up on PROGRAM_B pin) and switch FT2232H to FT245 mode which should make Spartan load it's bitstream from flash and initialize with 60MHz coming from FTDI.

And this last step is the thing I am not certain about. Will switching to FT245 mode leave pins of port B of FTDI in High-Z or in last state? Will Spartan wait for FTDI to put out FT245 60MHz clock?

This picture shows diagram of current connection (it's not polished yet because since it's BGA package I was trying to use optimal pins, but should be clear enough, for note 60MHz clock on pin 32 of ftdi is connected to GCLK0 of Spartan)


texts: Need advice on UPS circuit with variable voltage input

texts:
I want to make my own UPS circuit and I extended the one I found here so that I can connect 5V to up to 28V to it.

I've tested the circuit with some parts that I had laying around (not exactly the same, but with matching values), but when I disconnect power the voltage of the output "Vout" just breaks down to around 2V to 2.3V. This only happens when a load is connected, but I can't really figure out why?

Also I need to have around 6V or more at the output of the buck converter, that breaks down the 12V, so that I get 5.2V at the output "Vout". When I connect a load again it drops to around 5V. Could this be due to all of those diodes and their forwarding voltage of 0.5V?

Here is an actual schematic of the test circuit I used. The schematic includes wire lengths of the connected pcbs. The wires itself are 0.5mm^2.


texts: What PCB fabrication methods for *prototypes* are used by professional engineering departments today?

texts:
Ten years ago, I worked at a small engineering department within Philips Semiconductors that prototyped all designs before getting them professionally fabricated outside. The method was pretty standard:

Print artwork using a cheap laser printer onto semi-transparent film
Tape down top artwork onto bottom artwork and visually align them.
Cut a PCB to approx size, drill a hole at edge where a wire can be inserted to hold the PCB between insertions in chemicals.
Insert PCB between artworks, and expose using a homemade UV light box.
Hook wire into hole on PCB and dunk in a vertical tank containing Sodium Hydroxide and wait until developed
Put in spray tank and spray with clean water.
put in vertical tank containing Ferric Chloride etch and leave until etched.
put in spray tank and spray with clean water
put in etch remover until etch removed
Put in vertical tin tank for tinning.

The results were beautiful looking PCBs that were very easy to solder and professional looking, despite a lack of solder mask and screen.

Is this the standard method still used by professional engineering departments when making prototype PCBs today, or are there other methods that give similar great results?


texts: Getting ADXL345 accelerometer to work over SPI with Arduino Uno

texts:
I'm using this cheap ADXL chip with Arduino Uno. When I read the sensor with I2C - it works fine. However I have some servo motors as well which generate a lot of noise and when I turn the motors on, the sensor readings become pretty much useless.

I read that SPI is much more immune to noise, so I decided to go this way. However I just cannot get it to work with SPI.
I'm using this code, which seems to work for other people: https://www.sparkfun.com/tutorials/240

I triple checked the wirings, they seems ok to me, tried with and without level shifter, tried hooking up various pull-up resistors... and still I get just zeroes.
Yet I2C works just fine (without any pull-ups).

I'm wondering since the Sparkfun code uses a different breakout board for the ADXL chip - could it be that mine needs some specific pull-ups, that are not mentioned in that tutorial? How can I know what pull-ups need to be placed?

And any other suggestions will be much appreciated!


texts: What should I do with the unused Op-amp inputs?

texts: I am building a simple inverting operational amplifier circuit where I am using a chip with dual amplifier. I am only using one of the two amplifiers. What should I do to the unused amplifier's input pins? Should I leave them floating or is there a good way to sort of terminate them.


texts: How to deal with units in code implementation for PID-controller

texts:
Background: A robot uses two encoders attached to each rear wheel for feedback of speed. The program reading the encoders reads pulses per time unit. The encoders are sufficiently linear. The actuators are two DC motors attached to each rear wheel. They are controlled with PWM signals. So the controlled output signal is speed.
Problem: A PID controller is used to ensure that the robot wheels turn at the same speed so the robot can follow a straight course. The problem is that the program reads pulses/s while the output from the controller must be a PWM signal (a duty cycle value between 0-100). The system also faces different loads (varying surface friction and incline).
Questions

How do I convert between the two units (i.e. pulses/s vs PWM) in the program?
Even if I find a linear relation between input signal and output signal, doesn't this only hold true for a certain load (i.e. a certain surface friction and incline)?
If the answer above is yes, then what purpose does a PID controller even have in this system?


texts: How do I properly set this up in LTspice to determine Vin during rising and falling? I kind of a loss on how to answer this any help would be appreciated.


texts: Can I wire a transformer's dual primaries in parallel to double the output?

texts:
I have a dual primary (0-120V,0-120V) transformer with dual secondaries (0-6,0-6).  For a quick test of an amplifier board, I need a 12-0-12 supply.

What would happen if I wired the 2 primaries in parallel (or used just 1) and connect them to the local 240V supply?  Logic says the number of primary windings would halve and I would get the 0-12, 0-12 output that I need.

Or would it just smoke?


texts: Purpose of a resistor in active filter circuit

texts: I am currently analysing this circuit, and even though its purpose is clear to me I am unable to tell what is R17 supposed to do. Is it there just to set gain? I would be grateful for any explanation, as I don't have that much experience with hardware


texts: Current limits and sensors power consumption

texts:
I have example sensors datasheets:

1sensor
2sensor
3sensor

And I have supply current limited to 0.5 A.

Which current from datasheets should I take for calculations if my supply is sufficient?

There are:

effective operating current
no load current Io damped max
max no load current Io undamped
off state current Ir max

I thought that I should take effective operating current. But I saw working systems with 8 sensors with effective operating current 200mA supplied from 0.5A limited supply.

So the main question is which current should I take for calculations? And the second question is: could someone explain clearly what this four current values from datasheets mean and for what purpose they serve?


texts: 1kV DC Circuit - Insulation on ground wire?

texts:
If I have a 1kV DC circuit, does the ground wire need to be rated for the full 1000V?

The circuit is pretty simple, two wires from a power supply to a resistive load.


texts:
I have a board populated with Omron relays (G5Q-1A4-EU DC5) and I want to use them to switch circulation pumps (https://imp-pumps.com/pumps/ghn/). Is the previous relay appropriate to be used with said pumps?
From the information available on the pumps, they seem to act as a resistive load during operation. Is this behaviour only expected when they're under full load? If the relay switches off the pump while acting as a resistive load, is there a danger of an overvoltage appearing on the relay contacts?
If the relay mentioned previously is not suitable for this application, could it still be used if paired with the appropriate protection components? What would be the most suitable protection in this particular application? And if not, what kind of relay would be suitable for this application?
I know I just asked a ton of questions, but any help would be greatly appreciated. Thank you.


texts: I would like to power my robot with li-ion batteries. The logic is 5V so I thought about something like this http://www.powerstream.com/n-charger.htm. This does exactly what I want - it is charged with 5V and outputs 5V with reasonable 2.5A. Is this an ok chip? Are there any alternatives for that (shipping to Poland is 4x the chip :/)?


texts: My linear voltage regulator is overheating very fast

texts:
I'm using a 5 V / 2 A voltage regulator (L78S05) without a heatsink. I'm testing the circuit with a microcontroller (PIC18FXXXX), a few LEDs and a 1 mA piezzo buzzer. The input voltage is aprox. 24 VDC. After running for a minute, the voltage regulator starts to overheat, meaning it burns my finger if I keep it there for more than a second. Within a few minutes it starts to smell like it's burnt. Is this a normal behavior for this regulator? What could cause it to heat that much?

Other components used in this circuit:

L1: BNX002-01 EMI filter

R2: Varistor

F1: Fuse 0154004.DR


texts: Can I safely toggle the CS pin without sending any data?

texts:
Update: I've tried the solution I proposed in comments in practice (utilizing E pin on the 138 IC during changing target device) and it did indeed work. Read the whole thing if you want more details.

simulate this circuit – Schematic created using CircuitLab

I am trying to multiplex several SPI devices using a 74HC138 3-to-8 multiplexer. My program logic changed from typical "set CS low, SPI out, set CS high" to something like:

void selectDevice(int n) {
    digitalWrite(mux0, n & (1 << 0));
    digitalWrite(mux1, n & (1 << 1));
    digitalWrite(mux2, n & (1 << 2));
}

selectDevice(3); // my device
spiOut();
selectDevice(7); // dummy, not used

It works perfectly if there's just one device I'm talking to. However, there are some problems when two or more devices get used that way.

This brilliant answer has this:

  The CS line goes low, the clock cycles and essentially shifts in input bits and shifts out output bits, until the transaction finishes, at which point the CS line goes high. When their CS line is high, slave devices don't communicate: they ignore the CLK and MOSI lines, and put their MISO pin into a high-impedance state to let someone else use it.

This would make sense, but seems to directly contradict with the 74HC595 shift register behaviour for low->high ST_CP (so my CS) pin transition:

  contents of shift register stages (internal QnS) are transferred to
  the storage register and parallel output stages

The behaviour table and functional diagram basically state that ST_CP is irrelevant when the data comes in on SH_CP/DS, and it will be stored in the shift register. That would mean that if I write some data to other devices, and then briefly toggle the ST_CP pin, I'll write this garbage out! (assuming output always enabled).

As I see it, this is precisely what my selection code is doing, because the bits don't actually flip immediately; the multiplexer will go through other pins. Does that mean I need a separate pin to disable (make high) all of the mux outputs during the switching? Am I understanding this correctly?


texts: Can I use the Omron G6RN relay where reinforced insulation is needed beetween coil input and switched circuit?

texts:
I want to use a relay to control 230V power to an electric motor.

I'm considering using the Omron G6RN relay:

http://datasheet.octopart.com/G6RN-1-DC24-Omron-datasheet-10910301.pdf

According to the datasheet, it has:

Protection class II according to VDE0106 Part 1
Insulation class C/250, B/380 according to VDE0110.
Compliance with EN61810-1
4kV dielectric strength with 8mm creepage/clearance.

IEC 60950-1, which I'm trying to comply with, requires 4mm creepage and clearance, when designing for 2500V mains transients (2500V being the recommended design target for my class of product).

But, it also states that no single fault may create a hazardous situation. In principle, I'm trying to design my circuit so that the low-voltage parts fulfill the requirements for a SELV-circuit (i.e, a circuit with "safe" voltages).

IEC 60950-1 says, in paragraph 1.4.14, that a single fault is a single failure of any insulation (excluding double and reinforced) or a single failure of any component (excluding components with double or reinforced insulation). So, obviously it's not enough to follow the clearance and creepage requirements, one must also make sure that an hazardous situation cannot occur as a result of the failure of any one component that isn't adequately insulated (double or reinforced).

I have noticed that the datasheet for the Omron G7SA:

http://datasheet.octopart.com/P7SA-14F-ND-DC24-Omron-datasheet-8497433.pdf

states explicitly that the relay provides reinforced insulation between inputs and outputs.

So, what is the effect of all this? Am I allowed to do my own interpretation of the G6RN datasheet to conclude it does in fact provide reinforced insulation, or am I forced to select a relay for which this is explicitly stated in the datasheet?

I've taken apart a G6RN, and it seems pretty well thought-out. The mechanical arm that maneuvers the actual contact is made of plastic, and is more than 10mm long. There is no obvious way the relay could fail so that the insulation breaks down. Perhaps if the contact melts and hot metal is splattered all over the interior of the relay.


texts: Combinational loop in Verilog/System verilog

texts:
What's the difference between a += 1 and a = a+1 in SV/V?

always_comb begin
 a = '0;
 a += 1;
end

always_comb begin
 a= '0;
 a = a+1;
end

Is 2nd case combinational loop?


texts:
Recently I have been experimenting on DVR devices. I have one camera however I want to demultiplex it to three 16ch DVR devices.

I have been able to create a daisy chain to connect all 16 channels of one device to the 1 camera but i noticed a loss of video quality (video gets darker) and if I daisy chain 2 of the DVR devices the camera channels are completely black.

I did power the camera and the DVR devices separately as to minimize power problems. I suspect that the video line is not getting enough current or voltage and that results in the loss of video quality.

Any pointers or recommendations will make me very happy Thanks.

  Example of what I want to do.

  Example of daisy chain


texts: Do we need isolator after power amplifier in a microwave circuit?

texts:
I have been researching on the experimental setup for pulsed ESR. The setup consists of a microwave transmitter and a microwave receiver. I found that most setups use an isolator after the power amplifier[1][2]. In [2], it has been argued that the isolator is there just to ensure that the high power signal is not reflected back to the TWTA. Apparently, this could damage the TWTA. However, I am only using a solid state amplifier. In that case, is it necessary for me to use the isolator? Will a solid state amplifier be damaged by the reflected high power signal too?
Also why exactly does the TWTA get damaged due the reflected signals?


texts:
Im making lamps which are hand built, and each one is sold as a signed one out of a series of a predetermined number.

The lamps are made of plexiglas, they use an LED strip which is connected to a cable I make with a switch on it - that ends with a female connector like this one:

With the lamps I sell standard power supply that I buy in Europe (comes with a CE mark). The power supply has an output of 12 Volts.

I read lots of documents and still cannot figure out if I need a CE mark to sell in europe. the product is below 50V and it is art and does not fall in any of the categories of the CE mark.

Anybody had to deal with such a thing?

Thank you all in advance
Eitan


texts: Fundamentals of Output Characteristics of a BJT, what is the difference between load line and output characteristics?

texts:
In any transistor, we plot the output characteristics, i.e. effect of change in Vce on Ic.
Next, we write the KVL equation on the transistor, i.e. Vcc = IcRc + Vce and plot the load line from this equation.
So, now we have 2 relations between Vce and Ic - output characteristics and load line.
Why do we 2 plots for the same 2 variables, when will each be used and what all do they signify?


texts: We are doing home automation project. In that we are using triac for ac switching and snubber circuit (R=100ohm, c=10nf) for its protection. Here we have inductive and resistive load, for inductive load there is no problem but in resistive load when we connect less than 5W means it is glowing continuously without switching on. Suppose we remove the snubber for resistive load   it's not glowing. so how to reduce that small leakage via snubber. Please suggest me your solution.


texts:
I have made a layout using eagle then save it as PDF to print a test paper before routing.

I didn't design any package its all eagle's packages.
I exported PDF as shown on the image but the problem is :
the atmega16 and l293d and even ne555 packages are all scaled down on the printed paper !
as you can see on the other image i put the real component aligned with the printed paper
 but they didn't match ?!

What did i do wrong ?


texts:
We know that squaring a signal doubles its bandwidth.
Can you please justify this case in time domain for non sinusoid signals,say Rect(t/T)? On squaring the signal i don't see any changes in tine domain but convolution in frequency domain confirms double bandwidth. Please help on what I am missing here.

Reference: Effect on signal bandwidth due to multiplication?


texts: How much voltage before Zener diode will be physically damaged?

texts: I have this 1N4742 Zener diode which is specified to have 12V nominal Zener voltage. What will happen when I apply a 20V as a source voltage for circuit containing the mentioned Zener diode?


texts:
I send signals using the FS1000A, i.e. 433MHz. The module has a pin named "ANT", where I can solder an antenna, like a short piece of wire.

As the sender's range is not that far, I want to increase the range. Having basic knowledge in LC circuits, I thought that I could proceed the following:

According to the thomoson equation:

I need ideal values for L and C to get best range for a certain (here 433MHz) frequency. According to the following circuit, the capacity is 7pF:

So can I just connect an electromagnetic coil (i.e. coiling a piece of wire) having the right inductance L.

That would be true if it was a LC circuit. However, the antenna itself is a dipole antenna, so that I have to use other equations in order to determine the ideal parameters of the antenna. I know that the minimum length is λ/2 and every k*λ/2 (k in ℕ) works well. How does k influence the range? It is better to connect a electromagnetic coil instead of just a piece of straight wire, right?  How do i determine electromagnetic coil's parameters (length, ...), as I cannot use the equations above for this purpose, can I?


texts: Calculating resistor wire properties for my projects

texts:
I have a few things I wanna do with the resistor wire. They all involve getting approximate temperature using known voltage. I understand that temperature heavily depends on environment, but what I know now is nothing, which is much less that can be known in my opinion.

In the shop they offer wires with these 3 properties:

length
resistance
diameter

I have two general things I want to create

low temperature drying device for chemicals
high temperature electrical shisha

I wonder how could I calculate approximately which wire do I want. I would then test it to get the exact temperature. I understand this would need some additional electronics - but I'm sure I can first calculate the wire so that it's not burning red instead of slightly warm.


texts: Why doesn't LCR meter measure expected reactance?

texts:
Measuring an unknown capacitor with a Tenma 72-960 LCR meter, I got 89 nF at both 1 kHz and 120 Hz, which I believe because I measured other known capacitors, too.  Then I tried measuring with the resistance function, and it gave me:

180 kΩ at 1 kHz
1.5 MΩ at 120 Hz

But the reactance of an 89 nF capacitor is:

1.8 kΩ at 1 kHz
15 kΩ at 120 Hz

Also confirmed that in resistance mode, it measures 1 kΩ for a 1 kΩ resistor at both frequencies.

Why are the measured values off by exactly ×100?  Am I misunderstanding what the LCR meter measures?  (Is it magnitude of total impedance \$|Z| = \sqrt{R^2 + X^2}\$ or just the resistive component R in \$Z = R + jX\$?)

Update with some more measurements:

10 µF:

9.393 µF @ 1 kHz
9.71 µF @ 120 Hz
185 ohm @ 1 kHz (reactance is 16 ohm)
5.6 kΩ @ 120 Hz (reactance is 133 ohm)

680 nF:

683.5 nF @ 1 kHz
686 nF @ 120 Hz
63.22 kΩ @ 1 kHz   (reactance is 234 ohm)
cannot measure at 120 Hz   (reactance is 1.9 kΩ)

So the exact ×100 numbers may just be a fluke.


texts: Measure output AC voltage and current from a DC/AC inverter

texts:
As the title, I'm trying to measure and display 230VAC voltage and current from a DC/AC inverter on an oscilloscope. I don't know if I can proceed to measure them directly with these equipment:

-Oscilloscope: Tektronix TPS 2014b

-Differential Probe: TT-SI 9001 with the range of +-700V at 1/100 (CAT 3 1000 Vrms)

-Current Clamp: Fluke i30s with max current of 20 Arms

The inverter is pure sine Phoenix inverter 12|250. Power: 250VA and Peak power of 400W.


texts: calculate resistor value for transistor base

texts:
Below is a circuit where S1 is the output of a 555 IC timer (S1 switch for simplicity). I need to invert the output which I have done so in another project using the circuit below.

Starting with transistor Q2 which is a 2N3904 (datasheet), how do you calculate the resistor R2 needed if R3 or "Load" is 180Ω. The source will be 5V.
I'm having trouble understanding why Collector-Emitter saturation voltage is .3V where IC=50mA, when below it says for hFE4, VCE=1V, IC=50mA

Secondly how do I calculate R1 for Q1, to ensure Q2 is not driven.

I've have this circuit working with 12V and a 350Ω load. I used 1K resistors for both. I can't remember how I calculated it or if I even got it right.


texts:
I designed & assembled 3 copies of a circuit (BNO055 motion sensor board, used recommended i2c application from the datasheet).

1st one had some soldering issues, fixed them and it worked, received sensor data.
2nd one worked with no issues.
3rd is the culprit.

When I power the board everything looks fine, the ON led lights up, no smoke, no noise of any kind. The power supply shows 2mA current. But no data comes from the sensor.

Somewhere around 15th second the current starts to increase slowly. Around 20th second current reaches 10mA, after that within seconds the current reaches to 50mA and I cut the power, to protect the circuit.

I checked all the solder points, connector pins, etc. No bad solder, no short.

I connected the power again, same thing happened.

I wonder what would cause this behavior and how can I troubleshoot this problem.

I attached the schema & picture of the board


texts: How do I connect a microcontroller to the cellular internet network wirelessly?

texts:
I am working on a project where I have to wirelessly turn on and off Electric motor pump, which is at a distance of approximately 500 meter from my home. I need help to select the wireless communication so that I can send data from my home either to turn off or on the motor.
Also is it possible to connect my micro-controller to the internet of cellular network wirelessly(Without a GSM module)


texts: Setting Tpc of gate to 0, what prevents me from doing so?

texts:
I had the following question when learning logic gates in system verilog but found no answer for it:
We learnt a way to set the Tpc for any gate in code to any value we like, so want prevents me and others to set it to 0 and make things easier and produce the world's first "perfect" processor?
Especially since my professor told me if you do a project in system verilog you can send your design to manufacturers and they can build it for you.


texts: I want to use a 24 V DC relay with 24 V AC. Will the relay stop working? Is it safe to do it this way?


texts: TFT LCD interface with a Microcontroller: Getting Started

texts:
I have a small 3.5 in TFT LCD display from a Chinese manufacturer. It doesn't have an integrated LCD controller. The documentation claims it is a "16 bit RGB/parallel interface" and it uses a Renesas R61581B0 driver chip.

These types of displays are very common and cheap.  They sell for less than $15 a pop on Alibaba.com, but I don't really have a high esteem for these manufacturers since they do not provide any good / consistent documentation, and their English is riddled with mistakes! But I did get the display, and the product looks and feels like it will do the job!

My question now is, how do I get started ?  I have looked on the internet and cannot find a good starting point.  I have a 32MHz microcontroller in mind, but I am stumped on how to interface it with the LCD.

Most display projects online that I've seen assume that the LCD module comes with an integrated controller , so the MCU's job becomes pretty simple.. Provide image updates when necessary, and the controller will do the job of refreshing the LCD module at the required 60hz (or so)

This LCD module that I have has raw data lanes that I need to drive myself at 60hz.  Are there any good documents on how to interface an MCU directly with such an LCD module?

I'll be happy with any info that points me in the right direction, whether it be an answer on stackexchange or a reference to any good documentation online.


texts:
I am a student and I have to design a visible light communications project. The requirements are 20 cm distance between the receiver and transmitter, 20 kbps/s data rate and it must work in an already light environment. I have made a schematic and set it up on a bread board.

It works and I could probably fulfill my requirements, but barely. I'm driving my leds with a 20kHz square wave and you can see the result in the picture. The upper oscillograms are 1V per division and 50us per division(20 kHz) and are taken when I turn the leds towards the receiver. The lower ones are 0.3V per division and 20 ms per devision(50 Hz) and are taken when the leds are turned off so you can see the room lightning interference.

So my questions are:

How could I filter the 50Hz interference better? It is not showing too much when I transmit with the leds, but without them I have a lot of noise.
Should I choose larger caps and smaller resistors for my filters or the other way around? And what should be a good filtering frequency? For now I just played around with available component values and chose a frequency well above 50 Hz.
If you have any design advice I will be very thankful. I am a beginner at electronics so probably have some flaws.


texts:
I've just took for granted the fact that the input impedance of op-amp is high and output impedance is low.

I was reading "the art of electronics" lab book and there is an exercise that asks you to measure the output impedance of an op-amp by having the negative input connected to the output (1) and after the 1k resistor (2) while having and removing the 1k load resistor.

It isn't clear to me how it allows them to measure the output impedance of the op-amp.

The only equation I could write down was with the load resistor in place and the negative input connected to the output of the op amp, I have the following equation

\$\displaystyle V_{out} = V_{in} \frac{R_{load}}{R_{load}+1k \Omega + Z_{out}} \$

I thought this would give you the output impedance of the op-amp.

I wasn't sure what the rest of the steps are for.

From(Learning the Art of Electronics: A Hands-On Lab Course)


texts:
In this article, http://www.edn.com/design/test-and-measurement/4391393/Single-hex-inverter-IC-makes-four-test-gadgets,

 A circuit is used to detect a user degined low logic level and high logic level, by lighting a red & green led. It uses an "inverter" that to me works just like a mosfet gate. Top inverter looks like a mosfet with red led at source, bottom inverter looks like mosfet with green led at drain.

Regardless, they do not function as inverter at all (inverting logic 0 & 1 ). Logic inverter takes input of 0 or 1 (and has both supply & GND connections) . But in this case, looks like the gate to the "inverter" must be > threshold for it to work.

The use of inverter symbol confuses me. Why the need for it ?


texts: How does the inductive spike route through mains and effect this kind of system?

texts:
This is for a specific scenario.

Sometimes when a high current electrical device like an AC motor is turned on /off; or another crude example sometimes you have an inductive load sourced directly from AC mains controlled by a a manual bad switch and you turn the switch on/off. Sometimes one can even see some electric arc.

What type of noise is sent to the mains grid/wiring in these cases? I wonder how this kind of inductive switch effects other sensitive devices like TVs or radios or measurement systems for a short period of time.

Lets say there is a measurement system(transducer like an analog temperature sensor) and by using a coax cable it is send the measured voltage to an ADC.

And lets say that spiky inductive switching device and this transducer is powered from the same mains power plug or they are using the same line neutral.

How does the inductive spike route and effect the transducer or its coax line? Would that happen as a conductive or radiate way? How does the conductive way routes all the way to the transducer system?

The reason I'm asking is I'm wondering whether this type of noise through mains as conductive a common mode or differential noise. Would the spike/noise route through line or both line or neutral? How would it make it all the way to the coax through conduction?

Since it is impossible to track and see I cannot find an answer.


texts:
We have a new office doorbell with a pushbutton that rings a buzzer for as long as the button is held down (i.e. a simple circuit that is closed by the button). The buzzer sound is really "angry", and people tend to either:

hold the button down for long
ring again before someone has had a chance to open the door

.. which is driving me mad.

Is there a simple component to add inline to introduce a X second delay before the buzzer can be rung again? i.e. something that detects when a circuit is closed, and prevents it from being closed again for a configurable delay.

The accuracy of the delay length is not too important: e.g a variation of 5-15 seconds is fine.


texts: Using connectors rated for 250-400V with 5V

texts:
I have gotten a hold on a really great deal on Connectors for a electrical project of mine. These connectors come in various sizes, but common for them all is that they are rated between 250 volts to 400 volts. My system is using 12V and 5V.

The project is to connect a bunch of LED lights together in my garden on various distances. I am aware of current drop in the wires; I am just not sure what kind of issues I can encounter from these connectors.

So, can I use these connectors and what could the side effects be?


texts:
I'm trying to monitor speaker volume from its input signal. Input signal range is [-2.5; 2.5]V. I'm reading signal on an ADC with [0;3.3]V input range.
I did a simple circuit :

reduce voltage amplitude to 3.3V
add a 3.3/2V offset

Here is circuit :

Here are results of temporal and frequency simulations :

From results I have several questions :

first I put a 22k R3 value in order to get a Vout/Vin ratio ~ 0.68
that reduces input voltage to a 3.3V amplitude. I got an output
signal in [0.6; 2.6]V range. So I increased C1 without any changes,
after I reduced R3 to 10k to fit in [0.1; 3.1]V. Why?
this circuit is simple, but how can I simulate how audio signal is
deteriorated with this circuit?
do you have other circuits as suggestions?


texts: Why are there 3 conductors on a coaxial BNC connector and 4 conductors on a triaxial BNC connector?

texts: From what I understand, a BNC connector and it's cable has an inner conductor to route the signal and an outer conductor(cylindrical) to provide a shield to inner conductor and to provide a return path to signal. Triaxial BNC connectors have two shields, cylindrical connectors for better protection. But there's one conductor on these connectors, as shown in pictures below, whose purpose I don't understand.


texts: Termination ends orientation in toroidal transformer

texts:
I need to wind a toroidal transformer for a push/pull switch mode power supply (12V DC to 30-0-30 VDC). It would be much better for my pcb layout if primary endings would be at 12 o'clock and secondary at 9 o'clock. Would it cause any problems if wired in that manner?
Also is it important that primary winding would be equally spread acroos the core? And if yes is it better to leave bigger pitch or increase number of turns?


texts:
Can I use a small 12V A23 battery to power this negative ion generator?
Will it burn or will it last for long?


texts: Zener diode function in ringing choke converter

texts:
I'm referring to this video which I saw on youtube. I'm not sure the effectiveness. video 1

In this video, it shows that by increasing the zener diode value from 6.2V to 11.8V (by connecting 6.2V and 5.6V zener diode in series in the video,) the adaptor output will change from 5V to 12V.

I believe that the circuit is based on a ringing choke converter for normal adaptor and that the zener diode (6.2V) is basically used to regulate the  auxilliary winding's voltage in order to drive the transistor with constant current source. I found a reference circuit and its operation for similar adaptor in this link. ringing choke converter example

EDIT:

Add information as below:

Question:

Is it true that increasing the zener voltage at the auxilliary winding can increase the output? If yes/no, then why?
What make me so curious with this video is, from my understanding, basically the secondary output will based on the transformer turns. Is there any part/information that I am missing?


texts:
While reading about IMU on wikipedia I found this about its disadvantages:

"A constant error in attitude rate (gyro) results in a quadratic error in velocity and a cubic error growth in position."

How is Gyro drift error related to error in velocity and position?


texts: mounting orientation for Meanwell enclosed power supply

texts:
I am building a small system that includes two Meanwell LRS-100 series power supplies:

https://www.meanwell.com/Upload/PDF/LRS-100/LRS-100-SPEC.PDF

Note the photograph on the first page of the data sheet, and the drawings on the last page showing threaded holes along one edge and on the bottom of the unit.  I would like to mount the units standing up vertically (on the flat bottom of my chassis), with the narrow edge (with 3 screw holes) downwards.   From Meanwell's documentation, it is unclear if this is permissible, and if so, how performance might be de-rated.

Their one-size-fits-all installation manual:

https://www.meanwell.com/Upload/PDF/Enclosed_Type_EN.pdf

... states "Mounting orientations other than standard orientation or operate under high ambient temperature may increase the internal component temperature and will require a de-rating in output current. Please refer to
the specification sheets to receive the optimum mounting position and information about the de-rating curve."

But the LRS-100 series data sheet (the first link above) contains no such information.   Telephone tech support confirms that the unit must be installed within the end-system, and that the system must contain 3X the volume of the PS, and that ANY orientation is acceptable.  The agent did not inspire confidence, and I find this improbable: e.g. with the large flat side with ventilation holes facing downward, and the solid side (with two screw holes) facing upwards ?!?

So I seek guidance as to whether my vertical orientation is acceptable, and if so, how much de-rating might be required.


texts:
Q. Lower the self inductance of a coil  _.

Options :

more will be the weber-turns.
more will be the emf induced.
lesser the flux produced by it.
smaller the delay in establishing steady current through it.

Ans - option 4

But why is it so? why not the other options?
For the first option, I can say that if we increase the weber-turns, then it will increase the inductance which is in contradiction to the question given.


texts: No batteries power method (induction, motion, heat etc)

texts:
I am using an ATtiny85 to sleep for a long period of time, collect some data, send it over radio, and go back to sleep, after disabling everything possible. The ATtiny is currently powered by a coin cell. I can get quite some time off that coin cell, but it's simply not enough, and the coin cell cannot be changed once the board is deployed.

My aim here is to find an alternative power source for my board. Some good news is that the boards are never more than one or two feet from a receiver, so rf-like power transmission may be possible. Some other options may be motion or heat (it's a wearable device). The amount of power could be pretty small, as I only need it at peak periods, so I could just charge up a supercapacitor for a while and drain it when power is needed after the Attiny wakes up for less than a second.

The ideal situation would be to have a means of power transmission or generation that provides enough current to continuously power the microcontroller without the need for sleep, but I recognize that this is probably not feasible. However, due to the limited range it might be. Another concern is radiation to the wearer.

If anyone has any experience in this kind of power transmission or generation or just any ideas I would love to hear it. Thanks!


texts:
I got the following circuit:

simulate this circuit – Schematic created using CircuitLab

And this code to run it:

#define F_CPU 4915200UL     // Quarz with 4.9152Mhz
#define BAUD 9600

#include <asf.h>
#include <avr/io.h>
#include "helpFile.h"        // set/clear Bit (LED)
#include <util/delay.h>

void USART_Init( unsigned int ubrr )
{
    /* Set baud rate */
    UBRR0H = (unsigned char)(ubrr>>8);
    UBRR0L = (unsigned char)ubrr;
    /* Enable receiver ?nd transmitter */
    UCSR0B = (1<<RXEN0)|(1<<TXEN0);
    /* Set frame format 8data, 1stop bit */
    UCSR0C = (1<<URSEL0)|(1<<USBS0)|(3<<UCSZ00);
}

void USART_Transmit( unsigned char data )
{
    /* Wait for empty transmit buffer */
    while ( !( UCSR0A & (1<<UDRE0)) )
    ;
    /* Put data into bu?fer, sends the data */
    UDR0 = data;
}

void main( void )
{
    USART_Init(31);
    DDRB = ( 1 << PB0 );

    while(1)
    {
        USART_Transmit('C');
        PORTB ^= ( 1 << PB0 );
        _delay_ms(1000);
    }
}

If I connect this to an UART/USB Tool and start the Terminal Monitor with 9600Boud rate and 8n1 I get empty messages. Can you tell me what I did wrong / what to change to get it working?


texts: What type of processor in usual 8-digits pocket calculator?

texts:
There are a lot of +,-,*,/,CE,MC,M+,M-,MR buttons 8-digits calculators on market with keyboard layout like:

+----+----+----+----+
| ON | MRC| M+ | M- |
+----+----+----+----+
|  7 |  8 |  9 |  ÷ |
+----+----+----+----+
|  4 |  5 |  6 |  × |
+----+----+----+----+
|  1 |  2 |  3 |  - |
+----+----+----+----+
|  0 |  . |  = |  + |
+----+----+----+----+

Some of them have % and √ (sqrt) functions.

I wander what type of processor is under black epoxy lump? What is clock speed, registers bit width?

There are a lot of information about ancient '60, '70, '80 calculator architecture, advanced TI calculators and DIY projects but I can't find any mentioning of modern pocket calculator.


texts:
I'm trying to make a velocity-sensitive keyboard for playing music.

I have to measure the position of each key in order to know how loud the sound should be.

The volume of the sound is a function of the velocity of the keys at the end of the descent. I know the position can be recovered from the velocity by integrating it.

What would be the cheapest and easiest, yet still reasonably precise way to do it?

I don't know exactly what “reasonably precise” would mean in the context. I'll have to test it.

The length of the maximum displacement is about 2 cm.

EDIT: not as some answers seem to suggest, the loudness is NOT function of the mean velocity of the key.

EDIT2: The loudness is function of the hammer speed at the moment it hits the string, but the key isn't pushing the hammer until the end of its path. It is really like throwing a ball on a wall: the ball leaves the hand at one moment, before it hits the wall.


texts: What is the purpose of Vsense terminal in some amplifiers?

texts:
I am playing with old power op amps like Sanyo LA6510 : https://www.alldatasheet.fr/datasheet-pdf/pdf/40213/SANYO/LA6510.html
I would like to know the purpose of Vsense terminal ?
Additionaly I don't understand how to wire it. According the spec in Pinout, pin 1 is Vsense1, pin 2 is Out1.
But in Application notes, it's the opposite !
And there are no values advices for resistor.
For example I would like to use it as a simple factor 1 time not inverting amplifier.
I tried with 1k resistors wired as in application note but the output seem to oscillate with high frequency (1MHz) noise of several volts.
Thank you.


texts: For some type of op-amp circuits, the inverting terminal is placed on top, while on others it's at the bottom (i.e. inverting vs non-inverting amplifier). I don't understand the convention - how do you decide what to label each terminal? Aren't either labels valid since both terminals are equivalent?


texts: I bought a 30pF Variable Trimmer Capacitor, but am unsure how to adjust it. The lowest capacitance I am getting by adjusting the screw is 50pf, and it doesn't seem to matter which way I turn it. I contacted the seller again to get more info about the range (I need 2-22pf for my fm transmitter project) and he sent me this image, which I don't know how to read. I would really appreciate a pair of more experienced eyes telling me if this is the right capacitor (COLOR GREEN) for my project


texts: Difference between positive and negative LCD drive

texts:
I have a positive type custom ordered LCD with 60 segments.

Display type: Reflective
Duty: 1/4
Bias: 1/3

Now, i want to replace the positive LCD with negative type.

The LCD is presently driven directly by the micro controller. (MCU has dedicated LCD driver, SEG and COM pins, direct connections).

Question:

Do i have to change anything in the MCU firmware?
I believe i need not. Except the addition of back light control, because it is a negative mode display.


texts:
I am new to electronics and still learning so please don’t be too hard on me
Here is the circuit I am trying to understand:

To control to top PNP transistor, there is an optocoupler and 2 resistors.
When the opto is off, the base of the PNP is in series with the 10k resistor. I guess that the voltage on the base would be lower than the source voltage as the resistor will have a voltage drop.
If I understand correctly, the PNP will be on if the base has 0.7V less than the voltage on the emitter.
When the opto is on, then the base is in a voltage divider (in between the 10k and the 1k resistors) so then again, the voltage on the base should be less than the one on the emitter.
How can this PNP be turned off?


texts: Can a N-channel MOSFET used as a highside switch

texts:
Hello I would like to add a high side switch for my circuit. Typically a physical switch can do this job but due to form factor restraints the switches that are rated for my application does not meet the cut. To mitigate this is to use a MOSFET along side a lower power rated switch that meets the size limitation.

Usually you use a P-Channel MOSFET for highside switching but im having trouble looking for a part that meets the specifications in my supplier (3.3v ON 10+V 5-10A PMOS are not that common it seems). N channel MOSFETS on the other hand has a lot more of variety, but typically they are used for low side switching.

Is it possible to use an NMOS as a highside switch ? what are the disadvantages?

In my circuit i have a Reverse voltag protection IC that controls an NMOS on the highside. This makes me think that it is possible. I will just use the same NMOS for the physical switch as the one i will use for the RVP in series.

You might say why not integrate the physical switch to the NMOS in RVP, that seems to not possible as discussed here. The circuit would now look something like this.

EDIT:

I have found a document from texas instrument which is very interesting contains parts which could have everything in my circuit be contained in a single ic. On page 4 contains a list of features that i would want. what cought my attention is this ic TPS25942 it is a high side switch with reverse voltage protection and just requires minimal passives. What is important is i has an enable (EN) pin wich can be used by a physical switch


texts:
I am currently planning out a custom 3D printer build which will run on a 24V 600W power supply.  I have specked out for a $90 MeanWell supply from eBay, but I've noticed similar generic power for only $50.

I was wondering if there are any real advantages to spending the extra $40 on a name brand power supply....


texts: RC discharge in two ways, solving for time constant

texts:
Are the two underlined equations at the bottom correct (can I calculate an equivalent resistance for the time constant)? I understand how to find voltage and current for each element at time t supplied with DC voltage. So I’m looking at discharging two ways. Are they both appropriately solved?

Also I've just understood Thevenin equivalent circuit(s) solutions to these circuits so I specifically want to know if the time constant can be calculated by an equivalence resistance. Thanks guys I'm excited about every second I'll be  a part of this forum!


texts: A typical GPIO works at 150MHz without risk for EMI but why is there a risk of EMI at even 400KHz in I2C?

texts: In I2C the fall time is restricted to around 20ns as a risk of EMI(Even at 400Khz) but even a normal GPIO works at 150 MHz.Why is this so?


texts: How do I calculate the power rating for zero-ohm resistors?

texts:
Based on my earlier question, since there supposed to be zero voltage (V=IR) drop across a 0 Ω resistor, how do we select the power rating of such a component?

For example, let's say I were to connect a zero-ohm resistor in between 5 V power source and a load (circuit variant) which take current ranges from 20-200 mA. What is the power rating of the 0 Ω resistor I should select?


texts: Identification 4 pins crossing High-low voltage boundry, marked ABS10, 2 pins marked + -

texts:
What is the black 4 pin chip in the top left marked ABS10, beside the 15 uf cap, pray tell?  It bridges the hi-lo boundary on a 3amp USB power supply.

simulate this circuit – Schematic created using CircuitLab

Edit to add...

Thinking about the circuit, it seemed that the ABS10 would have to significantly lower the voltage, as the PCB slot ends at the far side of the device.  If high potential still exists there, the implementation would be violating the safety rules.  Therefore the ABS10 must be some new wondrous device that makes HV safe.  ({grin} Stupid me.)

I should have gone with Occam's Razor: given the source and past history of power supplies from there with UL case marking being added without certification, the design is defective.  The + and - markings should have shouted "rectifier" at me, not to mention the voltage rating on the capacitor.


texts:
Using a multimeter and set it on 200V DC - that's the lowest on this meter.
Tested a 1.5V and it reads 2.8
Tested a 3V and it reads 6.
Just replaced the battery.
The meter is ETEKCITY.
Any suggestions?


texts: Why do we need external and internal reference simultaneously in lock in amplifier?

texts:
IN this note on lock-in-amplifier, I see that there is external which we phase lock the internal reference to. Then the internal reference is used for phase sensitive detection.

My first question is why not using the external reference for phase sensitive detection directly?

My second question is if the input signal of interest have fixed frequency(of interest) but drifting phase. What will happen?


texts: How to reduce noise Buck converter at constant current mode ACT4088

texts:
Hello i am using a ACT4088US-T (datasheet here) Buck converter and i made it to run in constant current mode 500[mA] through a Diode (D5):
Everything works fine. It draws 500mA no matter the load i attach to it and the Voltage at FB is 0.81V all the time.

simulate this circuit – Schematic created using CircuitLab
But i get noise of about 280[mV] p-p (Peak to peak) max before the diode (Point A at my schematic). If i remove C2 and C3, the noise increases (thats why i have them there).

What are other ways to reduce the noise At point A?
Reading the datasheet of ACT4088, i think i can decrease the noise by using a larger Inductor (L1).  Maybe using a larger C1 would help?
Would bootstraping the output with a diode (Page 8 of datasheet, D2 diode) would help?
(Just for the record i tried adding a large 3300uF Cap after the diode, it didnt help much)
Probe is x10
Oscilloscope settings are:
COUPLING: DC 1MΩ
V/div Offset: NORMAL
Probe attenuation: x1
Thank you.


texts: Ignition coil arc initiation with protected low voltage continuation?

texts:
I'd like to initiate a spark plug arc with an ignition coil and then power the resulting (highly conductive) plasma with an ultracapacitor (low voltage, say 12V to 24V, and high current) without damaging the ultracapacitor during the initiation.

It would do something similar to this circuit:

But instead of relying on a 20KV power supply, it would be preferable to use a low voltage supply

I'm trying to avoid any arc-circuit resistance beyond the arc itself and the negligible ESR of the ultracapacitor.

I find the aforelinked PDF description of the above pictured circuit somewhat confusing.  It says the 20KV capacitor discharges through the inductor upon the Arc Strike Signal closing the switch -- but doesn't say anything about the timing of circuit in relation to the switch re-opening the circuit (which is presumably what causes the ignition spark).  Moreover, why would it not be sufficient to dispense with the capacitor in this role and dispense with the timing problem by increasing the induction of the coil, lowering the Igniting Power Supply voltage and then closing and opening the switch at "leisure" to produce the magnetic field and then the spark as with an ordinary ignition coil?  It's almost as if the description is off -- and that the capacitor is there only as a "snubber capacitor", to absorb the back EMF away from the Arc Power Supply.

Thinking along these lines:

Might the ultracapacitor serve as its own snubber capacitor if the polarity of the back EMF discharges the inductor-side plate?   Also, if the inductor has reasonably high inductance, it seems the Arc Strike Pulse Unit's power supply can be the same (kind of) supply (say lead acid battery) that charges the ultracapacitor.  Pehaps, something like this (I was unable to find a spark gap in the circuit lab parts so I used a voltage controlled switch for the arc):

simulate this circuit – Schematic created using CircuitLab

You close SW1 to charge the capacitor.  Open it.  Then close SW2 to establish the inductor field. Open it and the arc is initiated while the inductor's back EMF draws a small amount of charge from the inductor-side plate.  The sacrificial fuse then breaks the arc plasma's circuit after it is delivered a short, high current, low voltage pulse.

You can play with the switches and simulate the behavior at this falstad URL.

Is this conjectured circuit reasonable?


texts: Why is the RC value of a demodulator near the geometric mean of the period of carrier and message signal?

texts:
The figure below is a AM demodulator. My instructor told me to chose RC so as to satisfy
the following inequality Tc << RC << Tm. Where Tc is the period of the carrier wave and Tm is the period of the Message signal. I found that RC should be the geometric mean of Tc and Tm.
Why is this true ? and why is the best value near the Geometric mean.
-Thanks a lot for your time and inputs.


texts:
I've had an idea for a new form of SSB modulation, using half-angle formulas as a basis for compressing the sideband of a SSB voice transmission. However, this idea seems so simple that I feel it must have been proposed previously, even though I can't imagine a practical application except for possibly in the amateur bands.

Can anyone verify having heard of it and what is it called? My searches online and through IEEE Xplore don't reveal anything.


texts: Calling a function that's defined in an interface

texts:
I defined an interface and a function inside it as follows:
interface interface_binary_to_one_hot
#( parameter WIDTH_BINARY = 16 )
(
) ;
localparam WIDTH_ONE_HOT = $clog2 ( WIDTH_BINARY ) ;
    function logic [ WIDTH_ONE_HOT - 1 : 0 ] binary_to_one_hot ( logic [ WIDTH_BINARY - 1 : 0 ] binary ) ;
    automatic logic [ WIDTH_ONE_HOT - 1 : 0 ] one_hot = 0 ;
        for ( int index = 0 ; index < $size ( binary ) ** 2 - 1 ; index ++ )
        begin
            if ( binary == index ) begin
                one_hot [ index ] = 1'b1 ;
            end
        end
        return one_hot ;
    endfunction
endinterface

In another file,
I instantiate the interface and try to use the function inside it as follows:
interface_binary_to_one_hot
#( .WIDTH_BINARY ( 8 ) )
inst_interface
(
) ;

logic [ 2 : 0 ] binary_value ;
logic [ 7 : 0 ] one_hot_value ;
assign binary_value = 5 ;
assign one_hot_value = inst_interface.binary_to_one_hot ( binary_value ) ;

I expect "one_hot_value" to be "00100000".
But when I simulate - "one_hot_value" is all zeros.
What am I doing wrong ?


texts: Connecting lead-acid battery in parallel with lead-calcium battery

texts:
So I have a 12 V solar system (panels produce 20 V but batteries are 12 V. I also have a set of 5 batteries. One of these batteries is a marine deep cycle battery and the other is a group of five lead calcium batteries.
I read a lot about how PbCa batteries are Lead-Acid, so is it okay to connect these two dissimilar batteries in parallel to maximize usage?
What are the advantages and disadvantages of doing so?

Solar charge rate: 7 A max
Solar charge voltage: 20 V max OC


texts: Is GND isolation required to parallel a large number of power supplies

texts:
Suppose I have something like 50 independent switching regulators all tied a single load and ideally sharing current.  I could provide isolation for each regulator using a diode.

simulate this circuit – Schematic created using CircuitLab

Or I could provide GND isolation using a transformer.

simulate this circuit

For such a large number of power supplies in parallel, is there a risk of having massive GND noise on the shared GND plane from all the switching components?  Would GND isolation help address this issue?  If GND isolation is not required, what design considerations should be taken into account when sharing the GND?


texts: Unity Follower Circuit for Voltage Range 0-2.5 V

texts: Want to have a Unity Follower circuit which follows the input till 2.5 V. If Input exceeds 2.5  then it should not obey input rather a constant voltage of 2.5 V should be at output. I am a noob and a beginner So if there is any ambiguity in my question. please Excuse.


texts:
I am planning to using a buck / boost converter to run a DSLR camera from my USB powerbank AND other power sources.
For that module I want to build with the buck / boost converter, I need a simple LED voltage indicator circuit, since I need to adjust the potentiometer from the converter whenever I change the source of power.

Example 1

input: 5V from regular USB powerbank
output: 8.4V to the camera coupler

Example 2

input: 9V from DIY battery pack
output: 12V to other application

What I want the circuit to do is, when I turn the potentiometer, I want a LED to light up when the output voltage is between 8.4V and 8.6V ( ready for camera ). And when it's in an other range, I want an other LED to light up.

I've heard something about a combination of resistors and z-diodes to do the trick ?

Additionally it would be perfect, if the indicator circuit is not depending on whether the output circuit is closed or not ( camera is pluged in or not ).

Simple sketch:

Pleas tell me your ideas and solutions.

EDIT

I've found this link that shows this circuit

How does that work and how do I calculate the values for the parts ? I didn't understand the text on the linked page.


texts:
I'm looking for some help from the folks that know more about this subject than me.  I'm trying to install a break beam sensor to turn on/off an electric 6 rpm motor.  It powers a collator for a reloading press.  I currently have the motor hooked up to a 9v power modulator.  I'm not sure how to hook up the break beam sensor Sensor in order to turn the motor off when a feed tube is full.  Where does the signal wire hookup to?  Do I need a relay for the sensors?

They make these assemblies, but are rather pricey ~$500... So i decided to build my own.. Any who, I'm stuck on this step.
Any help would be greatly appreciated.


texts: How is the lh (load halfword) instruction implemented in MIPS?

texts:
I am a bit confused about lh (load halfword) instruction. Would it be correct to say that it gets the contents of the address just like in load word instruction but then takes the 16 rightmost bits and sign extends them?

So considering the picture above for load word, the datapath would be the same up to Read Data in Data Memory, but then the 16 rightmost bits would be sign extended and passed as write data to the register file instead of the whole 32 bits at read data.

Could someone confirm I am understanding the instruction correctly? It is sort of difficult to say what is going on.


texts: When prototyping diy PCBs, we would run a small wire from the underside of the board to the top and solder on both sides, wherever there was connection on both sides of a THT component, so there was good connection on both sides. I am about to order a batch of PCBs from JLC PCB ... do I need to use the same practice or do they coat the layers so that both sides are already making contact on the PCB?


texts:
I am very new to electronics. I know basics of logic circuits. I want to understand how exactly RFID works, is there a way i can design in PSPICE(This is the first software that i got for "googling" 'circuit design'. please feel free to suggest others that are Open-Source or free to use).

If i do try googling i get

although this tells me how it works, doesn't allow me to play with it.


texts: Feedback Gain Loss of Transimpedance Amplifier

texts:
I have designed a single-supply (3.3V) potentiostat that initiates electrochemical reactions, converts the generated electrochemical current into a voltage via a transimpedance amplifier (op-amp used was ADA4528), which then passes through a sallen-key low-pass filter and to an ADC pin on an mbed NXP LPC1768 development board. The ADC value is then sent to a PC and the current is back calculated and displayed in real-time on a graphical user interface. The circuit is similar in function to the one in the colorimeter CN-0363, which also uses ADA4528 as the transimpedance amplifier.

The feedback resistors tested were 16k, 160k, 1.6M and 16M. I've been using the Keithley 6221 current generator to test my board's function and applied currents that fall within the voltage output range of the op-amp for the different resistors. My system is very accurate till towards the end of the respective current range, after which I start losing gain. There is no discernible error for 16k, but for 160k and 1.6M, the gains started falling off at around 0.2V and 0.4V from the positive rail. The 16M was the worst at almost 1V from rail. I figure the gain loss is due to the limited output swing of the op-amp, when the internal transistors get out of the saturation region. However I do not know why different feedback resistors give different output swings, especially for a rail-to-rail op-amp like ADA4528.

I used the same 100pF capacitor to compensate all resistors, which based on calculations, is excessively overcompensating (though I should be operating at DC so this shouldn't be a problem?). However, I found out that when I put a 100nF capacitor with my 16M resistor, the feedback gain became very accurate, and the output swing was no longer restricted to 1V from rail. The side-effect was that there was noticeable "charging" due to a significant time constant.

To sum up:

Why does the output swing change for the ADA4528 when different feedback resistors were used?
Why did the 100nF capacitor "fix" the output swing limitation and gain loss issue of my 16M resistor?

Any help is appreciated! Thanks!


texts:
Here are a handful of capacitors, that I just salvaged from a burned out a 230VAC to 12VAC power supply. O those, I am familiar only with the electrolytics and how to read their capacitance, maximum voltage, polarity and maximum opperationg temperature.

What are the other cap types shown into the picture and how to read their parameters? Optionally, in what applications is each of those types preferable?


texts: What is the function of the voltage meter in this circuit?

texts:
simulate this circuit – Schematic created using CircuitLab

See the above schematic. I don't know if it's 100% correct, because it's my first time using it and some of the symbols are quite different to what I'm used to, but I think it's correct. So basically, my book says that the voltage meter in this circuit measures 0 V in this case. I honestly don't know why this is the case, and I don't intuitively grok the use of the voltage meter in this circuit. What exactly is it measuring, and why is 0 V in this case?


texts: How does a load decide the amount of current drawn in a circuit?

texts:
I realise this question might seem similar to other questions asked on the site. But what I'm asking is actually completely different.

Suppose I have a 5ohm resistive load hooked up to a 10v battery. The current drawn by the load would be equal to the current through the circuit, right?(assuming the load is connected in series). Using ohm's law, the current through the circuit would hence be 2A.

Now,if I connect the same 5ohm resistive load to a 15V battery, the current through the circuit would be 3A, using ohm's law.

So doesn't the same load draw different currents when the supply voltage changes? If that's the case, why do we say "current drawn depends on the type of load connected"?

Moreover does the above reasoning of using ohm's law hold valid for any type of load? (i.e. L load, C load, RL load or a combination of all 3)

Edit: this highly upvotedsays that for a constant voltage supply, current drawn depends on load. So how does the load draw two different currents for two different voltages?


texts: How do I setup a hardware watch dog timer with an Arduino?


texts: Why are flickering LED driver circuits cheaper than flicker-free circuits?

texts:
Many low cost LED fixtures have a 2X line frequency flicker.  Since flicker free switching LED power supplies are not difficult to design, I assume that flickering drivers are cheaper than flicker free drivers.

Some pictures of the driver from a low cost 120 Hz flickering LED strip fixture are shown below, followed by the typical application circuit for the on board BP2326A chip from this data sheet.

What is it about flickering driver circuits that makes them presumably lower cost and thus so ubiquitous?


texts:
I am designing an IF amplifier circuit that needs roughly 60 dB of gain at 20 MHz. I was considering a cascade of 3 x 20 dB MMIC gain blocks but I am wondering if there is a better way?

The disadvantage of the MMIC approach is that the power consumption is roughly 35 mA per device. So just wondering if I have overlooked something better. Cheers!


texts: How to adjust LEDs brightness with photoresistor?

texts:
My goal is to reduce LEDs brightness dynamically with LDR. Power supply is 12V car battery. LEDs are about 3V. LDR will vary from 10k to 100k.

I found out that I can use LM317 to adjust voltage. Now I do not know how to decrease voltage even more when it's dark out side (LDR resistance increases). I cannot use LDR as resistor for adjustments, because it will increase voltage when there is little or no light. I need just opposite.

I found circuits that use Pulse Width Modulation to adjust voltage with LM317, so that gives me an idea, that I can use op-amp with LDR to achieve what I want? But I am not sure how to wire this circuit correctly then.

This circuit might be right direction Problems controlling an LM317 with an op-amp


texts:
What is the reason that most of ICs (e.g. MCU) has multiple (A/D)GND and (A)VCC pins?

If it is to increase performance of an IC, how does it help to performance? or is it easier for the IC designer to connect some pins externally?

some footprint of ICs have a GND connection under the case, how does it help? Would it improve performance of an IC if I draw a GND under the case even if it is not required?


texts:
If I have an LTI system defined by the recursive difference equation:

$$y[n] = -\sum_{k=1}^{N} a_k y[n-k] + \sum_{k=0}^{M} b_k x[n-k]$$,

why can't I say the system is causal? The output at each time n depend on the past output values and the current and past input values.

Watch 9:28-9:56 and 10:25-11:50 of this MIT video  OR just watch 11:40-11:50 if you are short on time.


texts:
I am hoping someone might be able to help:

In the days when I started with computing (C64 and later Amigas) expansion slot cards with co-processing ability were relatively common.  I am looking for any modern analogue to this as I would like to build a Multi-CPU and GPU system, therefore I am looking for any information on products similar to this (wayback machine page here), preferably with an AMD CPU?

Any help/information greatly appreciated as I have searched online for quite some time with no real success.

Cheers in advance.

NB:  it looks like there may be an update from the original link, which leads to a product that may suit, if anyone else is interested: this I7 PCI card


texts:
If we assume that allowable inputs a, b and c are applied to the following logic gates, what is the output in terms of a,b and c?

I ran into the above problem, but I'm not sure if it makes sense. Because some NOT logic gates have two inputs which is not what I expect. I wonder if the problem is wrong or I'm missing something.

I need to calculate the output of the logic gates in terms of a, b and c  with logic operators like: \$\bullet \$ for AND, \$+\$ for OR, \$\overline{a}\$ for NOT \$a\$

I appreciate if anybody can help.


texts: why ohmic losses increase with resistance?

texts:
Electrical newbie here. I'm trying to get understanding how is resistance involved with power dissipation (ohmic losses, eg. heating). Primarily I'm looking at Electromagnet coil, it says the losses are \$P=I^2R\$, so reducing resistance R reduces heating power loss P, which sounds reasonable as it comes from (I assume):

\$P=UI\$ and Ohm's law \$I=\frac{U}{R}\$ (and thus \$U=IR\$), so by substituting U we get \$P=UI=(IR)I=I^2R\$

But, if one substitutes I instead, he'd get \$P=UI=U(\frac{U}{R})=\frac{U^2}{R}\$. Which seems to tell me, that with stable voltage source U one would get lower power loss (heating) with increased resistance R!

Which unfortunately also makes sense to me from empiric point of view: If I connect very high value resistor (or its equivalent - a veeery long wire) across 230V line, it would only heat a little, and I put very low value resistor across 230V line, it would heat so much it would burn (which I guess is what fuses do for living). (replace 230V AC with 9V DC battery if AC/DC distinction matters here)

So I guess I'm missing something basic - would increasing resistance reduce or increase power losses? Or is wire in "put it in 230V socket" example behaving completely different that wire in electromagnet example (and if so, why?)


texts: What battery do I use to power solenoid?

texts: Hello I’m quite new to electrical work and I’m trying to open and close a solenoid valve with a battery. I have bought these tiny 23a 12v battery. The solenoid says it needs 12v dc. I have no idea why it’s not opening all Insaw were some sparks. The battery can output 55mA but other than that I can’t tell you much. If anyone could tell me what battery I should use it instead that would be great as I wasted money on these batteries and I don’t want to waste money on other batteries that don’t work


texts: What is the difference between registers, flip flops and latches?

texts: I want the answer to the very basic level. I know what they mean individually, but what I am looking for is connection between them.


texts: Why RTS/CTS do not solve completely the hidden terminal problem and exposed terminal problem?

texts:
I was doing some reading online and textbooks about the RTS/CTS protocol for wireless transmission. Although, the textbook that I read said that the hidden terminal (and exposed terminal) is solved by RTS/CTS, online I saw that actually RTS/CTS protocol does not solve completely the problem. But only reduces is.

The protocol seems pretty neat and to me it looks as if the problem is solved. What am I missing here, why multiple sources claim that the problem is not solved?!

Are there hard assumption underneath the whole protocol?


texts: How to float the output of an optocoupler when needed?

texts:
I want to have an opto-isolated output which can be driven high, low or left floating. I thought of the following circuit but I'm quite new to electronics so I don't know whether it makes sense. Do you think something like this could work?

When EN from the input side is high, IC2 is supposed to drive the output high or low. When EN is low,  IC2's output should be floating.

As I understand it, when the transistor in IC2 is conducting, the OUT pin goes low. When it's not conducting, it floats. So, by itself, the optocoupler can drive the output only to ground or leave it floating. I want to drive it high also, am I understanding something terribly wrong?

Edit: Sorry my original question wasn't so clear about what I want to do with this circuit. I want to have multiple copies of the input/output circuit, preferably controlled with just one enable/disable circuit.

Also, I'd like to use a high speed device since one of the outputs will be a serial link and I don't know how to find a fast standard-type optocoupler.


texts:
I would like to create a synthesizer using 20 separate piezos for the triggers. In other words, each piezo would trigger a separate tone.

At the very least I would like to know if connecting 20 piezos to an arduino is realistic and how to do it.  I know there are only 5 analogue inputs.  Perhaps instead of each piezo triggering a separate tone, each could trigger the next tone in a cycle.  That way perhaps all of the piezos could be connected through only one analogue input.

I'm just not sure if this is possible or not, any advice would be appreciated.

This tutorial represents what I would like to do, only my idea calls for a larger scale.


texts: Low Side Current Sensing Grounding Question

texts:
I recently made a low side current sense circuit to test a power supply. It works well, but I am trying to understand the strange behavior that happens when I apply the negative lead of my probe to different places on ground. When I place the positive and negative leads directly across the .1 Ohm sense resistor, I get a very precise voltage measurement that I can then use to calculate the current. But if I move the negative lead further away from the negative side of the resistor terminal, yet still connected to ground, I start to get a voltage that does not accurately correspond to the current flowing through the resistor. Can someone explain what is going on? I have been reading some Microchip articles on low-side sensing and they briefly mention that ground references can become skewed, and they use the term "ground loops" which I am not sure I completely understand.
This is a crude drawing to illustrate the problem. As you can see, when I leave the positive lead on the positive side of the resistor, but move the negative one from directly touching the negative side of the resistor to a different spot on ground, represented by the blue pen, I get discrepant results.

Thanks for your input.


texts:
First of all sorry for the lengthy post - I'm trying to give as much info as I can.
I’m currently designing a PCB for a wall-mounted control unit which has control logic and mains switching/detection. I’ve done low voltage boards before, but not with mains on board.
I'm keeping the mains side well away from the logic side, and setting track widths based on a max temperature rise of 4C on 2oz board, but I'm not so sure about the small taps taken for mains detection.
To describe the circuit (see diagram) - there are 4x opto-driven mains relays (feeding 4x IEC sockets), 4x opto mains detectors connected to the SWITCHED LIVE feeds to the IEC sockets and two 5v PSUs (one for logic side, one for the mains side of optos) - all optos have slots for isolation.
The mains fuse is 5A, and all four feeds out of the IEC sockets (1.1A, 1A, 1A and 200mA loads) are each on 6A cable, with the mains input "bus" track to the relays also rated at 6A.
Each relay output is fused at 2A on the PCB, with tracks rated at 3A and the mains inputs to the medical grade SMPSUs are collectively fused at 250mA (track is rated at 1A).
I've not forgotten NEUTRALS: IEC NEUTRALS don't go via the board and are wired directly on the IEC sockets with 6A cable. For the PSUs they're rated at 1A, for NEUTRAL to the detectors they are (at the moment) rated at 1A, with the NEUTRAL "bus" rated at 6A.
But I'm trying to figure out the best way to deal with the taps that feed the mains detection ccts.
To me, logic says that their (and the associated neutral) track widths also ought to be >2A as the tracks are effectively fused at 2A. However, the actual current is under 1mA (there are 2x 220k mains-rated resistors and a 1N4007 in series).
I had originally planned to have these tap tracks rated at 1A - bearing in mind that these taps are already protected by the 2A fuses do I:
(a) set the track width to 2.5A (1mm and a bit tight)
(b) protect each with a resettable fuse rated at 50mA or
(c) is the risk so very low as to not be an issue? I don't think this is an option, but I include it anyway
And a related question - throughout the board LIVE and switched-LIVE will be at least 5mm away from neutral and other tracks/connections other than EARTH where it's 3mm. But should LIVE and SWITCHED-LIVE be similarly separated? I'm not sure that's possible, as even the mains relay contacts are only 2mm apart.
In writing this, I actually think I've figured it out, but any further input would be appreciated.
Thanks.


texts: How does the efficiency of a transformer change with it's load?

texts: How does the efficiency of a transformer change when the load changes, and why is that so?


texts: Long distance point to point microwave links - frequency and beam dispersion/angle?

texts: I occasionally see dishes on towers pointing horizontally, which I assume are long distance microwave links. Can anyone give me an example of frequency used and beam angle in radians of the directional beam?


texts: What will happen in an VFD if any two terminal of the output power given to motor (R,Y,B) are interchanged


texts:
The following diagram is of a power switching driver...the transistor is a switching transistor which drives load that requires to on and off ....
Can anyone tell me what exactly is the function of the diode here..they say that the diode is used to prevent reverse base emitter breakdown ...exactly how..??


texts: Interpolate variable 0-24v to power a 12v fan and control it's speed

texts:
I want to replace the two noisy 24v brushless fans on my printer with high performance silent 12v fans, more specifically Noctua A4x10 FLX

The 3D printer hot-end fan is on continuously with 24 volts, so I can use a DC regulator such as LM2596 to achieve a constant 12v to power the fan. The part cooling fan on the other hand uses variable voltage to adjust the speed of the fan during the printing process (Probably between 14-24V). I would like the 12v fan to be able to vary it's speed just like the 24v fan does. From what I understand using a LM2596 will not allow the voltage to vary and will just continue to put out solid 12v.

Is there a way to allow this variable fan speed functionality to translate to a small 12v fan? Is using a simple voltage divider circuit the answer?

UPDATE:

Thanks to Dampmaskins comment it looks like the variable speed part cooling fan is in-fact PWM. In that case is it possible to convert 24v PWM to 12v PWM?


texts: How to create a simple circuit with a torchlight, 2 AA batteries and a voltmeter?

texts:
NOTE: I AM A TOTAL NEWBIE ON HOW ELECTRICITY AND CIRCUITS WORK, SO STEP BY STEP WITHOUT TOO MUCH COMPLICATED LANGUAGE WOULS BE GREAT

Hi, I'm currently a middle school student and wanted to perform a small experiment on battery life, but am stuck on the first step on how to set it up.
Currently have 4 NiMh batteries and 4 Alkaline batteries with 4 of these Flashlights below, along with 4 multimeters. but am clueless on how to connect the multimeters to the batteries Whilst they are running (since I am recording the drop in voltage over time).
Do I need external battery holders, and if I do how do I connect that to the voltmeter and flashlight? Thanks
Here's the multimeter I have (all same model)
If battery holders are necessary, I am considering these


texts:
So i understand that a prescaler divides a clock, and PR2 is the period register which when the timer TMR2 reaches the value it increments from 0.
Why is a post scaler needed to divide a non-clock signal.
From the diagram it looks like the post scaler is trying to divide the comparator signal for when the first timer TMR2 reaches PR2 value.
I dont understand, couldnt another timer be used to identify when TMR2 reaches N iterations of reset?
Essentially i dont know what a post scaler performs and why it is used to divide a non-clock signal


texts: Can +48v DC Voltage be achieved by reversing the terminal of -48v DC voltage supply?

texts: I have a -48v dc supply that was achieved by grounding +48 terminal of the rectifier. Now can I get a +48v dc supply by simply ungrounding the pos terminal and grounding the neg terminal  ?


texts: 555 as a Schmitt Trigger and an ON delay timer?

texts: I've scoured the internet trying to find this out to no avail. I would like to use a 555 timer to produce a Schmitt trigger with an ON delay of 20-30 seconds. Is this possible? Or will I have to use two timers? If I can do it with just the one 555, can someone point me in the right direction as to how? Seems like you should be able to, but danged if I can figure it out!


texts:
I'm new to Arduino and was making a frequency counter using the pulseIn function.
The problem I'm facing is that the output values are very absurd, such as 66334, 883339,12, 34 etc. and not the actual frequency.
I'm using a 1kHz square wave from a 555 (shows perfect on the oscilloscope.)
Here is the code:
int in_pin=2;
float t_high;
float t_low;
float t_total;
float freq;
void setup()
{
  pinMode(in_pin,INPUT);
  Serial.begin(9600);
}

void loop()
{
  t_high=pulseIn(in_pin,HIGH);
  t_low=pulseIn(in_pin,LOW);
  t_total=t_high + t_low;
  freq= 1000000.0/t_total;
  Serial.println(freq);
}

Please help me out.


texts: What's the difference between passive matrix and active matrix?

texts: Both passive matrix and active matrix use "m+n" row-column addressing method to eventually switch individual components. So what makes one active and the other one passive?


texts:
I am doing a Bode diagram plot of the following transfer function:

$$G(s)=\frac{100 \, (s+2)}{s\, (s+10)}$$ that can be put in the form

$$\frac{20 (1+s/2)}{s\, (1+s/10)}$$

At \$\omega =100\$, can the magnitude in dB be calculated as

$$20 \log(20)+20 \log \left (\sqrt{1^2 + 50^2} \right)-20 \log(100) - 20 \log \left (\sqrt{1^2 + 10^2} \right)$$

The above gives \$-0.0415\$ dB as opposed to \$0\$ dB that I get on a Bode magnitde plot. At \$\omega =100\$, \$G(j\omega)\$ has contributions from all terms, so the magnitude calculation should include all terms. Is the above calculation ok?


texts:
If I short the three terminals of a bldc motor after switching off the supply to the motor, will that give me braking? And if it can how can I implement this?

I'm working on a project called Efficycle, which is human-electric hybrid trike.


texts: Measuring small capacitor parallel to big inductance (Network Analyser)

texts:
So what I have at hand is a cheap network analyser that can present the measured impedance in form of the values of different equivalent circuit topologies, e.g. R-L series or RL parallel.

What I want to do is measure the electrical parameters of a simple PCB antenna structure, which is typically modeled as as capacitor (mainly inter-winding capacitance) parallel to ( R + L).

So I did the "SOL" calibration and measured S11. Concerning R and L, I chose the available Network Analyser Representation of the equivalent circuit called "RL" (I have no C//(R+L) representation available)
This measurement shows the values for both, R-L series and R-L parallel equivalent circuits and I get reasonable values so no problem here.

But how can I determine the value of the capacitor? Is it possible at all? I thought of writing down the formula for the real and imaginary parts of the impedance of the topology I want to model (i.e. C//(R+L)) and solve it using the measured values of S11.
Besides of being inconvenient I think I would get a wrong result since any physically capacitance present in the structure is already indirectly included in the values i get for R-L (by having a slightly smaller L than without cap), right?

(Of course the inclusion of the capacitor in the presented R-L values is possible only for a specific range of frequencies because above some frequency the capacitor will dominate and "get visible" in the measurements, but that does not help either...)


texts: Voltage to current circuit simulation problem

texts:
I want to control current through of R8 resistor adjusting VS1 voltage. VS1 increased from 0 to 5V, but AM1 and VF1 don't increase or change.
Is there anybody give an idea about the mistake?

After comments
1)R4 reduced to 5Kohm
2)Drain and source swapped
Maybe better now. But it saturated.


texts: How does Solenoid works? How do I calculate its output power?

texts:
Here is a solenoid valve. It is a normally closed, which is mean, it is normally closed the valve. Vice versa, there is also normally open, which is mean, it is normally open the valve until it supplied with electric power to pull the rod. This type of solenoid available DC and AC current source.

What my concern here are how it work? How do I calculate its power requirement (Voltage, current), and its output power to force or to pull the rod so it close or open the valve as I explained above. What should be calculate here, is it B (magnetic field), or F (force)? And how to calculate it?


texts: What are these component on behind of this circuit?

texts:
This is a circuit which was inside a rechargeable light. Purpose of this circuit is to supply power for charging mobile phone. I see some components on behind of this circuit what are those?
behind:

front:


texts: SparkFun Sound Detector Circuit Analysis

texts:
I would like to request some help in analyzing the op-amp circuit used by SparkFun here. I'm particularly interested in the pre-amplifier portion of this design.

The write-up included by SparkFun mentions an arithmetic gain of 100. When I simulate this circuit with LTSpice and provide a 10mV 8kHz AC sine wave signal as the input, the output I am getting is ~0.55V 8kHz sine wave. How can this be? I would expect an output of ~1V 8kHz sine wave.

A screenshot of my spice setup is below, I'm using standard part values from the built-in libraries on LTSpice:


texts:
I have 9v DC motor that I want to use to lock a door. Control is achieved using an esp8266 board. The esp8266 also switches the direction of rotation via an H bridge. So far, so good..

Now I want to detect the stall at each end of the motor travel. Initially Im trying to do this without the H bridge, just for simplicity.

There is a good amount of info about the subject out there, but Im afraid my electronics knowledge is poor and thus far I havnt been able to get anything to work.
My approach has been to use a .1 ohm sense resistor with an lm311 as in this circuit below.
The supply is an adafruit variable voltage module delivering 9v and Ive tried a number of different pullup resistors. Im afraid I just dont understand enough to work this out.
Regardless of the R pullup value.. 1,5,10 K and even without it, the output seems to wobble arounf 1.8v setteling down to about .9v. When the motor is stalled I detect no change at all in the output.

In an ideal world, I would get I nice 3.3v on the output when the motor stalls so that I can deal with it in software.
Id be grateful for help. Thanks


texts:
Looking at the reference design given for INA826 in the image below, what would my best options be if i wanted to replace J8 with something allowing me to switch in R19 (sense resistor) from a microcontroller (3.3v GPIO)? I am thinking something like a FET, but my design knowledge on the subject is not strong enough to know how to do this with the lowest possible impact on my current readings?
The final circuit will be used to measure inputs on J9:
Voltage: +/-10V, +/-5V, 0-10V, 0-5V, mV Inputs
Current: +/-25mA, +/-20mA, 0-20mA, 4-20mA, 5-25mA
So the solution should preferably support bipolar loops.


texts: USB-C Power Delivery with a buck converter

texts:
Following on from my previous question: The project I'm designing requires a peak current of 5V @ 6A. The average current draw will be more like 2A.

The reason I'm looking into USB-C is that I want a connector that is low-profile, reversible and I wish to use the power delivery capabilities of USB-C (3A/20V). I won't be using USB-C at all for any data transfer, only power.

There are many chip solutions that I've seen, which I'm still combing through. My plan is to use one of these chips to negotiate with the PD source a supply of 3A/20V. (As an aside, this project is a one off, and will be "supplied" with an appropriate USB-C PD source). However, the project required 5V @ 6A, so I was going to use a buck converter. I haven't actually looked into what buck converter I can use to fulfil these requirements (any help on this would be appreciated), but I've seen some chips which seem capable of providing at least 5V/6A from a 20V supply.

My main issue is that to start the PD negotiation "Profile 1", which provides 5V @ 2A, will be used. Presumably I'll have problems supplying the buck converter with such a low voltage.

Does anyone have any experience of designing a similar circuit? Do I need something that will stop the VBUS of the USB connecting to the buck converter if the voltage is less than ~20V?

Update 1

Initially I've been looking at providing power to a USB-C control chip at the original 5V that VBUS will supply. There are a few on the market that offer what is known as "dead battery" or "no battery" support. However, these chips also provide all the multiplexing and other data services which I don't require, and are a bit out of the scope of the project.

One chip I've been looking at is the TUSB320 which will allow my USB-C port to act as a upstream facing port/sink. The plan is to use a LDO with an input voltage capable of at least between 5V and 20V in order to use VBUS power to power the TUSB320 chip. One possible contender is the UA78M33 which has a fixed output of 3.3V. This means that the chip can remain powered no matter what the VBUS voltage is.

As far as I can see (although further research is still required), once the higher voltage and current has been negotiated from the USB supply, the voltage will transition from 5V up to 20V with a maximum slew rate of 30mV/μs.

The LDO will also power the microcontroller, so that it and the TUSB320 can communicate over I2C. Once the higher voltage/current arragement has been negotiated, then the buck converter (next thing to look into) will be enabled (by the MCU) and power the 5V side of things.

Update 2

As Ali Chen correctly pointed out, the TUSB320 doesn't support the high power 3A/20V that I require. After some research I've found the FUSB302 from ON Semi. It's almost a direct replacement in terms of how it will run. My plan to use a LDO to supply the FUSB302 from VBUS still stands. Updated circuit diagram is:

I found a very useful link online from someone who converted an Easy Bake Oven to run off USB-C. Furthermore, he has written some libraries (modified from the Google Chrome EC library) that help use the FUSB302.

The next step in this project is choosing an appropriate buck converter. I'd also like to look at the efficiency (or potential inefficiency) of using a wide-range LDO that supports the maximum VBUS voltage (i.e. 20V) to continually run the MCU. Otherwise, the two viable options I see are:

Swapping over to the buck-converted 5V once the VBUS voltage is at 20V.
Finding a buck converter that supports input from 5V up-to 20V, but only enabling the high current drawing devices once the VBUS voltage is 20V and 3A current can be supplied.


texts:
I am looking at using the STMF103RB ( ST product page ) for a use case involving being asleep for 1 second and UARTing 500 ADC samples and then going back to sleep. I have a 50mAh battery and need it to last atleast 10 hours, i.e. 5mA average.

Sleeping - sample ADC at 500Hz, with an ADC sample time of around 5us and DMA this into a memory location.
Awake - UART these 500 samples as fast as possible and go back to sleep.

My problem lies in estimating the minimum clock speed required to process this to estimate battery life. If I plan on using the ADC at a sample rate of 500Hz, a sample time of 5us (lets say 8 cycles) and the ADC takes ~12cycles to convert = 20 cycles, lets say 30 to be safe. Does this mean the clock can be at (30*500 = )15kHz whilst asleep to do this? Is it possible to find out if this okay for the DMA too by calculation? This clock speed in sleep would put it <1.08mA typical current (according to datasheet) and give me more than enough legroom to UART for a short time.

Similarly if I want to UART at 115200 Baud, does this mean my min. AHB and APB clock speed is 115.2kHz? Or is this simply too slow for the processor to process its code too?


texts: PCB Connector Footprint - Through Hole Diameter - IPC Standard and Datasheet Specification

texts:
I'm creating a footprint for a molex PCB connector (Drawing PDF here).

The datasheet contains a section for PCB layout.

For the connector leads it states a diameter of 1.02mm with 0.04mm tolerance.

I understand that the IPC standards provide guidance on selecting a hole size based on the component lead size.

Should I assume that the diameter measurement in the drawing is the hole size, which should be followed directly, without increasing it? (or is it the lead diameter size)
What does the box just below the 1.02mm measurement mean (the one containing [0.10|A|B|C])?


texts: PIC mathematical operations weird problem

texts:
I am trying to display the voltage value on my specific GPIO pin. I use PIC18F26K83. I can read ADC value. ( I tested it and it gives correct results.) ADC_read() function gives me 12 bit number. Now in order to find the voltage value I need to follow this calculation:

adc_value*(4.9)*(11) / 4096

My voltage reference is 4.9 V and I have a voltage divider 1/11. So I need to multiply the adc_value I get, with this:
4.9*11/4096 = 0.01315917968.
But when I multiply them like this, I get something incorrect:

int adc_value= adc_Read(0);
adc_value=adc_value*0.01315917968;

I supposed to get something around 11. ADC_Value is around 1100. But the result of this calculation becomes 2.... Where am I wrong with this calculation?


texts: How to decide the cut off frequency of an LC filter for a spwm?

texts:
How to decide the cut off frequency of an LC filter for a pulse width modulated sine wave with fundamental frequency 50Hz and switching frequency of 10Khz?

I want to know factors that are needed to be considered in designing a filter which is to be implemented with a pure sine wave Inverter.

The following figure is the output waveform of the inverter across a resistive load without filter.

I understand that the cutoff frequency must be below the switching frequency and above the fundamental frequency. But what would be the optimum cutoff frequency and how to calculate it?


texts: What is the purpose of a microcontroller bootloader?

texts:
From my understanding, for a common microcontroller (e.g. AVR, PIC), there are generally two methods of programming its flash memory.

Using a programmer: In-Circuit Serial Programming (or some variant?)
Some form of a bootloader, to which an external device communicates, ultimately allowing the microcontroller to flash its own memory.

Certainly there must be a very good reason to use a bootloader, else its current widespread use would be very odd. I just haven't seemed to have fully grasped it yet.

Is it that a programmer is expensive? But then, there are Arduinos (ATmega microcontroller) which can function as programmers. Is the cost of one extra IC enough to warrant the use of a bootloader? If I'm not mistaken, the latest Arduinos get rid of the FTDI chip altogether, replacing it with an ATmega processor that does the USB to serial interfacing. Surely it would be possible to integrate the programmer's function on this IC for instance?

Or take for example, the PIC microcontroller. There is something I've seen called the JDM programmer. If something like this, with virtually no active components, can program a PIC then,

Why use a bootloader at all?
What is the purpose of the relatively much more complex PICkit (aside from robustness)? Debugging capability?


texts: V-trigger to S-trigger stops when devices share ground

texts:
Many of you who make audio circuits are likely familiar with the following simple design:

It takes the gate output (typically a +5V pulse) from one piece of analog electronic audio gear, and uses it to close a switch on another piece analog electronic audio gear (using a transistor).

Recently I've used this little circuit to take the gate signal from one piece of gear (I'm using a LepLoop) and trigger (or close) the "push" of the One-Key-Play button on my old Casio PT50. This allows the Casio to be sequenced in time. It works great, for the most part. More specifically it works while playing sound out of the Casio's speaker, and with headphones plugged in. The problem arises when I plug the Casio's audio output into a mixer which also receives audio output from the LepLoop. In other words, the LepLoop sends gate-out to the Casio and sends it's own audio to the mixer. In this setup the Casio is no longer triggered.

Some strange things to note:

The actual gate pulse can be faintly heard on the Casio channel on the mixer. I'm guessing this means that the gate pulse found an easier path to ground through the Casio rather than returning to the LepLoop through the gate cable?
I can also get the S-trigger to stop working by simply touching the grounds of the audio out cables from the LepLoop and Casio together (mixer aside).
Checking the transistor emitter and collector with a multimeter, I get beeps in rhythm with the gate (but notes are not triggered). I think this means that the switch is still closing when the devices share ground, although I'm not sure how accurate this test is given that the test leads may be affecting the circuit.
Using a multimeter on the LepLoop, I tested between the ground from the gate out and audio out, and found that I get beeps when the gate fires a pulse, so this means they share ground during gate pulses.

I've tried modifying the circuit in a hundred ways using different arrangements and values of resistance and diodes with no luck. At this point I'm pretty stumped so any help would be greatly appreciated. If I can't figure this out I might be forced to explore solid state relays for this application. Any suggestions there would also be appreciated. Thanks!


texts: What is this inductor symbol? Straight line with 90° and 45° intersection lines

texts:
In the picture below, what does the symbol labeled with "L11" stand for?

The letter L and the 10uH suggest it is some kind of inductor, but the symbol seems rather non-standard to me.


texts: Is it possible to use an SD card without a file system?

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I'm doing a project on PIC, which needs a large amount of memory to store data. I want to use an SD card as the memory storage element. I don't want any type of file system.

I googled the interfacing of SD cards with microcontrollers. I found that all of them are using some kind of file system. Is it possible to interface an SD card without any file system, like a serial EEPROM?


texts: Multiplex two I2C ICs into four 7 Segment displays

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I currently have two PCF8574AN I2C 8-bit IO expander ICs. Is there a way I could have two seven segments be driven off one IC (So i could run four seven segments displays off the two ICs that I have). I have thought of wiring an extra pin to a transistor which enables and displays each, in turn.

Is there a better way to accomplish this? I could just simply buy two more ICs to run the four seven segment displays(different addresses).


texts: Does a "frequency-modulated" signal mean that the frequency isn't consistent? and therefore it has a specific bandwidth of frequencies is can cover??