texts: Calculating power requirements of components

texts:
I'm just starting out learning electronics, so please forgive my ignorance. I want to control a bunch of small 10W CLR light bulbs using Arduino. I have this MOSFET module:
http://www.mouser.com/ds/2/34/TinkerKit_MosfetModule-188845.pdf

It says "This module lets you control devices operating at a maximun of 24VDC with an Arduino pin", but nowhere on the data sheet does it tell you the amps. Don't I need to know that in order to calculate how many 10w bulbs I can operate? W = V * amps right?


texts: HFSS - Replacing a variable with a new variable

texts:
I want to put two similar designs in a single design. Both designs share some common variables with different values. When I put them together in a single design the common variables share same values and thus destroy the designs.

So my question is if there is any process/script which can allow me to replace a certain variable with a new variable?


texts: How to add through-hole pads within polygon pads in Eagle?

texts:
How do I properly add through-hole pads within a polygon pad in the package editor and device editor?

This is what I have tried:  In the package editor, I have created a polygon pad on the top layer.  I have added many through-hole pads within the polygon pad.  In the device editor, I connect/append all of the through-hole pads to a schematic pin called "GND".  Then, I add the part to my schematic and generate the board file.  The problem is that when I open the board file in the layout editor, there is a complicated ratsnest between all the through-hole pads.  This confuses me because these pads should already be connected electrically.  Why is there a ratsnest?

What is the proper way to do this?


texts: Does anyone on here know why a camera's accuracy would drop when you reduce the delay time after the pulses?

texts: I'm using a TSL1401R-LF Linescan Camera that reads in a 1 X 128 array of pixels. Here is the datasheet. When I used 170-microsecond delay the accuracy was pretty high and the camera's outputted values were noticeably lower when an object passed through its line of vision. When I attempt to reduce that to a 20-microsecond delay I would still see lower values if a cover the camera completely or higher value if I shine a light on the camera, but the change is slight and there is not change if I hold an object from a distance. The lower the delay time, the worse the accuracy. This confuses me because the datasheet states that the minimum delay time can be as low as 20 nanoseconds for the SI pulse and 50 nanoseconds for the CLK pulses. Since I'm still clearly above the minimum why am I losing so much accuracy? I've never worked with a camera or scanner before so I'm not sure if this is normal of if I'm doing something wrong.


texts: Considering Moding Issues in High Speed PCB Design

texts:
My question is a more generic one. I recently learnt about TE and TM propagation modes in waveguides. This made me think that when designing high-speed PCBs people always talk about matching the characteristic or differential impedance of the line; however, I have never heard somebody considering the case of moding issues in PCB design.

So the cutoff frequency for a mode m in a parallel plate waveguide is given by:

where  m is the number of the mode, c is the speed of light, n is the refractive index (for FR4 this is approximately 2.1) and d is the distance between the copper traces.

I calculated that if the thickness of the FR4 between the copper traces is 0.2mm then there will be TE and TM modes propagating down the transmission line at frequencies higher than 360MHz.

I know that moding causes dispersion which creates issues with signal integrity. This made me wander why I've never heard people considering this type of issues when designing PCBs. Are there any cases in which it must be considered?


texts: Calculating uncertainty in a current divisor

texts:
I had the following exercise to do for college:

I designed an analog ammeter exactly like this:

simulate this circuit – Schematic created using CircuitLab

The idea is to design an ammeter capable to measure up to 1 mA, with the D'Arsonval galvanometer of 50 μA. So we put a shunt resistor of 26.32 ohms to redirect the excess current.

The problem is that the shunt had an uncertainty of 3%, everything else is exact. So to calcule the uncertainty of the ammeter I do the following calculations with the current divisor:

$$I_{m}max = I * \frac{R_s max}{R_s max + R_m} $$
$$I_{m}min = I * \frac{R_s min}{R_s min + R_m} $$
$$\Delta I = \frac{I_{m}max - I_{m}min}{2} $$
Defining epsilon as the uncertainty:
$$\varepsilon = \frac{\Delta I_{m}}{I_{m}} $$
And Rmax and Rmin are:
$$R_{s}max = R_s + 3\%R_S$$
$$R_{s}min = R_s - 3\%R_S$$
Ok lets do the math:
$$I_{max} = 1mA * \frac{26.32 * 1.03}{26.32 * 1.03 + 500} = 0.05143\,mA$$
$$I_{min} = 1mA * \frac{26.32 * 0.97}{26.32 * 0.97 + 500} = 0.04858\,mA$$
$$\Delta I = \frac{0.05143 - 0.04858}{2} = 0.001464\,mA $$
So the result is:
$$\varepsilon = \frac{0.001464\,mA}{0.05\,mA} = 0.029 \simeq  2.9\% $$

The problem I found doing this is when using other method: uncertainty propagation, the result is considerable different when we talk about uncertainty, look:

Considerer the uncertainty of a multiplication is the sums of each uncertainty, and to get the uncertainty of a summ first u have to calculate the absolute uncertainty of each.

$$\epsilon = \epsilon (I) + \epsilon (\frac{R_s}{R_s + R_m}) $$
Uncertainty of current is 0 by definition.
$$\epsilon (\frac{R_s}{R_s + R_m}) = \epsilon (R_s) + \frac{\Delta(R_s + R_m)}{R_s + R_m} = 0.03 + \frac{\Delta R_s + \Delta R_m}{R_s + R_m}  $$
Uncertainty of Rm is 0 by definition so lets do math:
$$\epsilon = 0.03 + \frac{\Delta R_s}{R_s + R_m} = 0.03 + \frac{26.32 * 0.03}{26.32  + 500} = 0.0315 \simeq 3.15\%$$

Results are different and I cant figure out which one is correct. I think is the second one, but really dont know. I realize that in the first method when calculate Imax if the Rs in numerator is Rmax and in the denominator is Rmin, same for Imin, I get the same result as in the second method, like this

$$I_{m}max = I * \frac{R_{s}max}{R_smin + R_m}$$
$$I_{m}min = I * \frac{R_{s}min}{R_smax + R_m}$$

But I dont think that is correct to do, cause I am treating each Rs as differents variables.

Thanks everybody!


texts: soldering wires between two points on a perfboard

texts:
I have two IC holders and I want to connect a pin from IC1 to a pin from IC2 using a wire.
my current approach is soldering the IC holders and later just reheating the solder on a pin, sticking in a 30awg wire and letting it cool again.
the problem is sometimes it doesn't cool down and neatly as it was before, and I'm wondering if the connection is as good as it was...

is there some better technique?


texts:
What kind of uses do engineers find for 1 pF or lower-value capacitors?

This is the kind of value one gets with two bits of wire close to each other or two tracks.


texts: Two capacitors of same value connected in series and connected to power supply instead of one capacitor of equivalent value for PCB design

texts: what's the purpose of two capacitors of same value connected in series and connected to power supply instead of one capacitor of equivalent value for PCB design especially for Automotive applications


texts:
If I were to make a make a footprint, even for a simple component like a 0603 cap, and the manufacturers recommendation differs from IPC-7351, would it be recommended to start with the manufacturers footprint or the IPC footprint?  A very specific example is the TDK C1608X5R1A475K080AE where TDK would have me make a pad that is 0.6~0.8 mm wide and IPC-7351 would have me make a pad that is 1.0 mm wide, with differing lengths as well.
In the end, I would think that a lot of influence for this decision would come from the CM (contract manufacturer) that is holding the ball with respect to assembly reliability but without CM input, what is the general thinking on a good starting point.
Bias: Sometimes I wonder what good IPC is as I interpret it as simply collecting and dissemination information about existing practices and by definition, always behind the curve on assembly techniques.  None the less, I am still looking for a comment or opinion on my question.


texts:
I'd like to make a 5.1 audio switch to enable my 5.1 audio system (+mic+headphones) to be available for any of the 4 computers it can be connected to.
So I guess I would have :

INPUT : 4 (computers) x 5 cables (x2 wires (stereo) ?) - 5 cables are 3 for the 5.1 audio, 1 for microphone, 1 for headphone
OUTPUT : 1 (audio system) x 5 cables (x2 wires  (stereo) ?)

And I don't see the beginning of a way about how to do that properly.
By properly I mean, first do it, second avoiding current issues like current going back to the system or interferences that could damage the electronics.
Note : I'm used to solder electronic components, but I know nearly  nothing about electronic theory.
I found this as a starting point / reference, but it is only for 2 inputs, and it uses RCA connectors instead of jacks.
Could you help me ?


texts: why unipolar NRZ scheme 's normalized power is double that for polar NRZ?

texts:
I was reading a textbook which says:
Unipolar NRZ scheme is very costly. the normalized power (the power needed to send 1 bit per
unit line resistance) is double that for polar NRZ. For this reason, this scheme is normally not used in data communications today.

I'm confused, for polar schemes like NRZ-I, they commonly uses 2 values (+ and -). so the normalized power should even be higher or at least euqal than unipolar NRZ scheme. For example, let's say the voltage representing 1 in unipolar NRZ is 2v. so the normalized power is 1/2X2X2 +1/2X0X0 = 2, and for polar schemes it is 1/2X2X2 +1/2X(-2)X(-2) = 4, so normalized power of polar NRZ > unipolar NRZ's?


texts: USB Product as both Host and Device without OTG

texts: Can a product behave as a USB Host in one setup and as USB Device in another setup without having USB OTG capabilities? My intuition says that this is not possible, since if it was, there would not be a need to develop OTG in the first place.


texts: USB-C Powering Electronics and its Circuitry

texts:
I recently designed a PCB that'll power and control a NEMA 17 stepper motors. I decided it will be powered by a 15W (5V3A) USB-C cable and wall adapter. According to my research, the 15W power is the standard USB-C power without the PD (power delivery) protocol. Because it didn't use the PD protocol, I  I thought can just connect the Vbus & GND and that'll get me the 5V 3A draw. Therefore, I left the CC1 and CC2 pin not connected as shown in the picture below:

However, as I looked into the PD protocol, I found this info where it still uses the CC1 and CC2 pin under standard USB-C power. They had this Rd resistors added between the CC1 and CC2 pins.

I've already submitted my PCB to the manufacturer for production (a small batch of 5 pcs). Would the USB-C wall adapter and cable still be able to power my PCB without the Rd resitors?


texts: My DC motor has no-load current of 60 mA max and load Current of 300 mA max. What does that mean?


texts:
I'm an electronics student, advanced in some matters, beginner in others. I'm researching about building a board for digital audio processing. The idea is to get it work on the cheapest way. For that i'm thinking to take advantage of old motherboards and pci sound boards and reuse their audio codecs. The first board that came to me had an AC97 chip. So i started to search on web if there are any library written for Arduino. Reading and reading on various posts and webs I found a lot of info but I have many questions yet.

The question is that, can an Arduino manage the serial AC-Link of the codec? I get that is a 256 bit communication at 12Mhz.

Another question is, can I reuse an AC97 library for a linux kernel (for example) to work in Arduino? I'm a software developer so i'm disposed to hack it to get it work with Arduino, but, what kind of work should be done for that? (it only redefines the pins? are there instruction incompatibilities by the cpu architecture?)

I'm lost in some issues. I'll appreciate if somebody can guide me a little.
If you encounter some confusion in my idea, tell me and i'll try to speak better.


texts:
I'm working on some project which is not really related to digital circuits but rather boolean algebra analysis.

In some point I stucked at algorithmic or maybe data structure problem:
How to effectively determine if given truth table is equal to another one (when we take into account that they can differ at order of inputs).

For now I hold truth tables in bitvectors
for example nand truth table will be stored as: 1110 because:

A | B | R
0 | 0 | *1*
0 | 1 | *1*
1 | 0 | *1*
1 | 1 | *0*

However for some circuits thruth table in my representation might look tottaly different for the same circuit when inputs order is changed. For example:

simulate this circuit – Schematic created using CircuitLab

Truth table:

A | B | C | R
0 | 0 | 0 | 0
0 | 0 | 1 | 1
0 | 1 | 0 | 0
0 | 1 | 1 | 1
1 | 0 | 0 | 0
1 | 0 | 1 | 1
1 | 1 | 0 | 1
1 | 1 | 1 | 1

but when we change A <-> C inputs like:

simulate this circuit

truth table become:

A | B | C | R
0 | 0 | 0 | 0
0 | 0 | 1 | 0
0 | 1 | 0 | 0
0 | 1 | 1 | 1
1 | 0 | 0 | 1
1 | 0 | 1 | 1
1 | 1 | 0 | 1
1 | 1 | 1 | 1

So at it is visible I cannot just compare my "raw" form of truth tables for this case because 01010111 != 00011111 while from my perspective these truth tables represent exactly the same circuits with only inputs order difference.

Is there any smart representation of truth tables which will allow me to check this kind of equality and tell me which inputs from first thruth table maps to which inputs from second one?

For now I only have idea to generate all "raw" thruth tables based on inputs order permutations for given "start" truth table and during comparation check if any of these permutations is equal, but this is very memory consuming and slow method.

Do you have any idea how to solve this problem? Maybe there are existing scientific papers about this?


texts:
What's the minimum lead length for a component in order to reliably connect with solderless breadboard contacts?

Reading specs on cables, relays LEDs, and other components, what should I take as the minimum distance from the bottom of the device to the tip of the lead?  Or put another way, from the top of the breadboard to the pinch-point of its contacts?

I want to plug into a generic solderless breadboard and not worry about loose connections.  I have assumed through-hole PC board leads would be sufficient but occasionally they are not.  Case in point, a flex cable from Digi-Key has leads that are about 3.2mm or 0.125in long that keep falling out.  So the answer may be just a little longer than that.

This spec from 3M says nothing about this dimension, except that the standard interconnect wires go about 0.250in deep.


texts: how to convert 0 to 5 V signal into 4 to 20mA current transmitter

texts:
i want to make a voltage to current converter which is also known as current transmitter. i want to  convert 0 to 5v into a 4 to 20mA current loop which can be received by a powered load. i want to make the circuit using op-amp. please someone help me by suggesting some tested circuit.
thanks in advance

simulate this circuit – Schematic created using CircuitLab


texts: Reading registers from ACS71020 over SPI

texts:
I'm trying to read registers from current-sensing chip ACS71020 connected over SPI.

This is how I initialize the SPI:

bc_spi_init(BC_SPI_SPEED_1_MHZ, BC_SPI_MODE_0);

The code for reading is such:

    uint8_t tx_buffer[2]= {0x1E | 0x80 };  // Register to read with highest bit set to 1
    uint8_t rx_buffer[4] = {0x01, 0x02,0x03, 0x04};

    if(bc_spi_is_ready())
    {
        bc_spi_transfer(tx_buffer, NULL, 0);
        bc_spi_transfer(NULL, rx_buffer, sizeof(rx_buffer));
        bc_log_info("rx_buffer1:%d", rx_buffer[0]);
        bc_log_info("rx_buffer2:%d", rx_buffer[1]);
        bc_log_info("rx_buffer3:%d", rx_buffer[2]);
        bc_log_info("rx_buffer4:%d", rx_buffer[3]);
    }

`
Is it correct to set the highest bit of the register to 1 when reading? That is how I understand the spec.

Also no matter what register I read, I always get the same four values back. Is there something I'm missing?

I'm using the Big Clown (STM32L083CZ)
https://developers.hardwario.com/hardware/about-core-module


texts: Drain-Source Bandwidth of MOSFET As RF Load Switch

texts:
I have a DC-coupled input signal up to 2GHz which I would like to connect or disconnect from a 50 ohm load before it is buffered.

I think it should be possible with just MOSFETs, my idea is as follows:

So, to disconnect the 50-ohm load, I'd apply -5V at Vg, in which case Vs = (-3V to 3V), and Vg < Vs, so no current can flow.

To turn on the 50-ohm load, I'd apply 5V at Vg, and Vg > (Vs + 2) in all situations so the MOSFETs are on, and Vs approximately 0V since current can flow and Rdson is low.

Does this work?
How do I choose MOSFETs so that the bandwidth along the Drain/Source paths is up to 2GHz?


texts: Parallel connect 2 batteries while the panels are separate?

texts:
I have 2 solar panels, 100w and 125w. They will separately power one 100ah battery each. Can I parallel connect the 2 batteries for charging purposes or should the batteries separately go to the same 30amp charge controller to then charge my stuff? This is a 12v system.
Thanks for any help.


texts:
Given an opamp to which we can apply a supply voltage of 5v. Does this mean it has to be only +2.5 and -2.5 V or could it be 0 and +5v. Is there a difference?

Thus is it possible to convert any opamp to a single supply opamp


texts: In mesh analysis how are currents negative and positive?

texts:
I'm trying to do mesh analysis for the following circuit. I take the clockwise direction for the current as it's general convention.

The reference shows that this results in

I don't understand how the +,- terminals are marked for resistance and how VS1 becomes negative. Can someone help?


texts: What is the relationship between Teagueduino to Arduino?

texts: How are Teagueduino and Arduino related? Can the Teagueduino IDE be used to program Arduino boards? What is the "upgrade path"? The relevant section in the reference ("Migrating to Arduino and Beyond") is blank.


texts: Can the same 3V source be used for 2 different circuits

texts:
I'm trying to combine 2 circuits on a micro:bit - one to operate a PWM motor and the other to drive a 7 segment display.  I'm doing this on a Kitronik breakout board https://www.kitronik.co.uk/pdf/5601_edge_connector_breakout_board_for_the_bbc_microbit_datasheet_1_0.pdf

The 7 segment display has a 5V pin but seems to work from a 3V source provided by the micro:bit.

I don't know much about electronics so I thought I'd ask this while trying to figure out how to rearrange the components so that everything fits on the breadboard.

The two circuits work individually and both require a 3V source.  There are two 3V pins on the breakout board.  I've looked at various projects but I haven't found one where they're driving 2 components off the 3V source.

The question is: Would it be OK to use one pin for the PWM motor and the other for the 7 segment display or should I power one of them from a battery?


texts: Why does the output of this opamp change my analog signal?

texts:
I am trying to make an inverting Op-amp circuit in LTSpice where I can invert an analog signal without any gain on my signal, I want the signal to stay the same but inverted. I have followed the basic inverting Op-amp circuits that I have seen in electronics text books.

I have followed it through using the OP27 op-amp provided in LTSpice and got results looking like this:

I don't know how to explain what happened here but it happens with the other models of op-amps as well on LTSpice except for the ideal op-amp.
Can someone explain what happened to the signal? Is it a problem with LTSpice? or is there something missing in my circuit that could solve it?


texts: Is IMU sensitivity always equal to FS / resolution?

texts:
I'm in the process of evaluating MEMS IMUs for a new design.

According to this post, if a Gyroscope's range is ±250°/s, and its resolution is 16-bit (0-65535), then sensitivity can be calculated as: \$\frac{500°/s}{65535LSB}=0.0076\frac{°/s}{LSB}\$.

I am looking at the accelerometer on the Bosch BNO055.  It has a FS range that is user-selectable between ±2g, ±4g, ±8g, and ±16g.  One would assume that you would calculate the sensitivity likewise.  i.e. if FS=±2g, and accel is 14-bit, then sensitivity is: \$\frac{4g}{16384LSB}=244.14\frac{µg}{LSB}\$.

However the datasheet says the sensivity is fixed which is rather confusing.  Does this mean no matter what FS you set, it's impossible to see increments of less than 1mg?

Parameter: Sensitivity
Symbol: S
Condition: All FS Values, TA=25°C
Min: -
Typ: 1 LSB/mg
Max: -


texts: Power and control 3 phase ac induction motors with dc source

texts:
Background

So we are making a drive system to be used in a medium sized catamaran. The catamaran will use two water-jets powered by two 3 phase 380v ac induction motors. The entire system will be powered by two large 48V dc battery packs.

As the motors are powered from dc batteries we need to convert this to 3 phase ac and then transform it up to 380 and apply a speed controller. But this entire system becomes quite expensive, so instead we are thinking of creating our own conversion and speed-control system.

Question

So I am looking for a controllable circuit(preferably with pwm) to generate required 3 phase output that i can use to drive mosfets that will switch the main dc input. I will later transform this to my required voltage level.


texts: assembly timer code [ C8051F340 ] explanation

texts:
Hi my problem is that I cant understand this code when I test it on my microcontroller  Si Lab [ C8051F340 ]and let it run step by step

My problem is basically is when I test the program on my microcontroller ( I dont feel confortable to post the whole program ) the program counter arrives to the instruction "jnb TF0, Innere_Schleife" and stops there . I can still see my microcontroller 7segment display changing . But I dont undertand why and how the program counter just stops there and doesnt jump to the next instruction although I can still see changes on my board .


texts: Why does MOSFET get damaged when used as a switch in a RF remote control circuit?

texts:
simulate this circuit – Schematic created using CircuitLab
Update: The MOSFET gets damaged when not running the motor even once. Maybe even without connecting the motor at all. There is an alarm module in the circuit as well that I am powering from the point where the relay coil is connected.
I've connected an N-Channel MOSFET (https://pdf1.alldatasheet.com/datasheet-pdf/view/52370/FAIRCHILD/FQP30N06L.html) with a motor (i.e. brushless motor controller) and tried to control it using a RF remote receiver. RF receiver has an MCU that triggers the relay. The motor runs at 54V while the RF receiver runs at 12V so, there is a DC-DC converter that supplies the source voltage for the receiver. The gate of the MOSFET is driven by +12V from the converter and is shut by connecting it to the ground. The circuit works fine for a while (or at-least when not connected to the motor) but when in operation the MOSFET becomes damaged. I have also placed a flyback diode however, MOSFET is still getting damaged. The gate becomes ineffective permanently and it doesn't stop the flow of current even when connected to the ground. A gate-source shortage is then observed.


texts: Am I right with select of base resistor?

texts:
simulate this circuit – Schematic created using CircuitLab

I did add the NPN 2N3904 because I want to put on sleep the Arduino. So I need to put LOW the GPIO when goes in sleep.

This is a prototype. I will port on an Arduino Mini 3V3.

I did forget the pullup from gate, but cannot edit the schema :(

Load is 5V display, with MAX current usage of 67mA. So per OHM Law, I got ~75 Ohm.

Arduino is 5V and his GPIO drive ON/OFF the 2N3904.

I did study that it is common to assume that base current is 1/10 of the collector current. But, what the collector current in my case? That 67mA?

If yes, I need to select a resistor for

5V (Arduino) - 0.9 (Vbe per datasheet) = 4.1/ (0.067 /10 ) = ~600 ohm?

For R2, Do I need to do same absumption?


texts: What are the NAND Trees that Ethernet datasheets refer to?

texts:
I have read a few Ethernet transceiver datasheets and they always have some short section akin to "NAND Tree Support" or "NAND Tree I/O Testing", and from what I gather from these small bits of information is that they offer some standardized facility for hardware fault detection.

In general, they describe how to enable NAND Tree mode, what pins are probed, what order they are probed in, and how to read the results of the test. But none of the datasheets I have read to date have provided an in-depth description of how these tests actually operate.

Can anyone shed some light on this for me?


texts:
I recently designed my first PCB, which uses an ESP-01 to control 4 relays. I planned to use this to control my home appliances, which run at 220V. But I made a rookie mistake, instead of placing screw terminal width holes for the relay's COM, NO and NC terminals, I placed standard 2.54 mm spaced holes. I have the ordered (and received the) PCBs already, so was wondering if I can still use it with some changes.

I'm thinking of using 2.54 m right-angled female headers and connect them to the screw terminals. But I don't know if they can handle 220V. And my track spacing towards the end is too less for 220V, is it safe enough for a maximum current flow of 0.5A?

I do not wish to waste these PCBs, so any suggestions on how to use/modify them will be highly appreciated.

And what's the worse that can happen? If my PCB gets a short circuit or something, I believe my appliances will turn on even if the relay is off. Or maybe some other problem can destroy the PCB or damage the components (which are cheap). But can anything riskier happen?

Thank you.


texts: How to select a diode with enough reverse voltage in buck DCDC regulator?

texts:
Is there any experience on selecting the proper reverse voltage on asynchronous buck regulator?

I want MP2451(Vin 36V max) to work well in a wide range of input voltage(5-24V) and convert it into 3.3V, will a 1N5819 with reverse voltage of 40V meets needing? Or a larger redundancy is needed?

Thanks.


texts: Calculating Wavelength of sound using an Arduino

texts:
I'm using an Arduino Uno R3. I need to measure the wavelength of sound of a particular (known) frequency. By substituting in the equation:

Vsound = Frequency * Wavelength

...I wish to calculate the speed of sound in the medium. Since I'm new to Arduinos and electronics, I plan to use a speaker for generating the (known) frequency from the Arduino. I have an ADMP 401 microphone as well. But how do I process/calculate the wavelength of sound on the Arduino and push the output velocity to the serial monitor?

EDIT: Is it possible to simply take the audio recorded by the ADMP 401 microphone and push it to a computer via the serial bus?


texts:
I want to connect devices which output S-video (Y/C) to my TV, which only has YPbPr component inputs. One of them outputs PAL (European) while the other outputs PAL-M.

One way to do this would be to chain video decoder and video encoder ICs, which gives me flexibility on the color systems but an AD/DA conversion seems unnecessary to me as I understand that I just need to separate the Pb/Pr signals from the incoming C signal. Also this seems like a fun project to undertake.

How could I go about doing this separation? Are there any ICs to help me out on this?


texts: Testing plan for flat flexible cable (FFC) connector

texts:
I'm taking an assembly of three boards to a small production run.  There's a main board (n=25) and a satellite sensor board (n=100).  The sensor board connects to an adapter board, which simply connects the sensor to the main board through an 8-conductor FFC.

The main board is a USB device, reading signals from a variety of sensors through a harness as well as the FFC, and sending the signals as an HID. I'm thinking about the QC (and have been for a while). The contract assemblers would like to know that the components they're working with are good, of course.  Since there's only 25 main boards, I thought testing each one for enumeration on a PC and making sure the signals from the test harness come through isn't that unreasonable -- I figure 2 minutes per unit, max.

For the sensor board, I figure on providing a kitted test platform to test the sensor, with maybe an led bar display.  Twenty seconds a unit, max.

The issue is the ZIF FFC connection between boards. I'm using these connectors  I'd like to hold down this testing, as I think it will be slow and fairly tedious.  I'm thinking about spot-checking about 3-5 units, and going for visual inspection of the solder on the connectors for all the rest (they're fairly large pitch).

Does this make sense? Does it make more sense, with respect to the FFC's, to test the first few off the run then a random sample?

I've had zero problems with the hand-populated prototypes, which have really been run through the mill.  I'm using a very reputable local board assembly plant that routinely constructs to mil-spec.


texts: Pi-Matching network needed when already 50Ohm matched on transceiver?

texts:
I've been dreaming up a small gadget featuring a NRF51822 MCU as a centerpiece and I'm a total noob at RF-voodoo. I want to use a chip antenna. My question is this: Do i need this matching network

From the MCU/Transceiver or this one

From the chip-antenna datasheet or both?

I found some talk online of mixing the two together somehow but that was with a different configuration on the output of the MCU.
Can someone help me or point me in the right direction?

Link to the MCU datasheet

Link to antenna datasheet


texts: How to determine best wireless technology for my application

texts:
I'm trying to help a buddy research implementing some form of wireless communication between a dozen or so self-contained sensors to collect data placed outside around a small area (less than 20ft between nodes) and send that data off to a central point.

Each unit will be self-powered (battery) and encased in some form of metal tamper-proof casing and possibly even embedded into exterior walls so only 1 side would not be covered by building material.

He's been looking at a 802.15.4 PAN implementation using 915mhz.

I'm a software guy and not very familiar with electronics, let alone something specific like RF communications. So I just need some general help in understand how to choose the correct wireless communications package for this scenario.

802.15.4 PAN looks like it will fit the bill as it comes to having nodes communicate with each other and reporting that back to a PAN Coordinator but is 915mhz the best frequency to use?

I know this is a very high level and vague set of questions, I just don't know where to start other than asking on the StackExchange network.

UPDATE:
Looks like ZigBee is going to be my best bet. Low power consumption, runs at either 2.4ghz or 915mhz, bandwidth should be sufficient, good range, and most of the network code is done for me.

I searched Mouser for ZigBee and got a ton of results, from what I can decipher the differences are mainly in form and power output/range. Not sure what else I would be looking for.

Is there a preferred company for these modules?


texts:
I would like to drive a 3x3 RGB LED matrix multiplexed. This means each RGB LED has 1/9 duty cycle and that means it consumes 1/9 of total current. The RGB LED I am using is designed for max 35 mA continuous forward current that means: 35 / 9 = 3.8 mA for each LED which isn't very bright. Its peak forward current is specified at 1/10 duty cycle, 0.1 ms pulse width and max. 100 mA. The datasheet gives me this diagram to determine the forward voltage:

As you can see on the Y axis the maximum current is 35 mA. How am I supposed to determine the forward voltage for 100 mA?

Complete Datasheet: http://www.csd-electronics.de/data/pdf/LL-509RGBC2E-006.pdf


texts: Why is there always a capacitor on input and output of a voltage regulator?

texts:
Looking at the datasheet I can see that the voltage regulators are not just a zenner diode inside, they are complex devices. I have noticed that there is always a capacitor at the input and another one at the output. An example is the uA7800 series fixed voltage regulators.

I have read that one of them is to "stabilize the circuit operation" while the other is to "reduce ripple on the output". Looking at the datasheet, why do they have this fixed value? And if they do have a fixed value then why not just fabricate them into the voltage regulator itself? e.g for the uA7800 series it is 0.33uF at the input and 0.1uF at the output. It is not explained why they have these values.


texts: Powering RD-ZD-25 DC 110V 50W bread machine motor?

texts:
I have a RD-ZD-25 DC 110V 50W bread machine motor that I'd like to use on a ball mill project but I can't find what sort of power it needs. Am I safe to assume it wants 110V DC?
EDIT (by jonk) to add sample pictures from ReduceScrapping.com:


texts: How to make a fan speed regulator with a pot and a voltage regulator?

texts:
I want to make a simple fan speed regulator, but my electronic skills are failing me. I want to be able to slow down two computer fans.

I have in my hands a 12V/1A power suply, 2x 12V/0.2A fans, a B10K potentiometer and a 7805 and a 7812 ICs.

Can I make it with those? If yes, how? If not, what do I need for that circuit?

Thanks


texts: Reason to connect a bidirectional tvs diode in paralell with a unidirectional one

texts:
I am designing my own high-side smart load switch for my power supply using TPS27SA08 ic.
I decide to investigate how it works this evaluation board https://www.ti.com/lit/ug/slvubd4b/slvubd4b.pdf?ts=1612274192754&ref_url=http%253A%252F%252Fwww.ti.com%252Flit%252Fpdf%252Fslvubd4
that uses the same ic I mention.
At Vin the board use this components:

I can not understand the reason why they use a bidireccional tvs diode (D3 https://www.st.com/resource/en/datasheet/sm6t39ca.pdf)
with a unidirectional one (D4 https://www.st.com/resource/en/datasheet/smcj30a.pdf).
As far as I know with a bidirectional one you obtain the same clamping voltage in both directions. Also this two diodes have different breakup and clamping voltage.


texts:
I brought an ATmega328P (SMD) and burned a Duemilanove Bootloader. Everything seemed to be working fine until I tested out conditional statements.

Average set of analog val are: 84 , 143 , 255

Here is the code:

int svalue(int analogVal){
    if((analogVal > 135) && (analogVal < 200)){
        return 1;
    }
    if((analogVal > 200) && (analogVal < 300)){
        return 2;
    }
    if((analogVal > 50) && (analogVal < 100)){
        return 3;
    }
}
// Here is my main loop
void loop() {
  int pval = svalue(analogRead(A1));
  mySerial.write(pval);
}

But the above code is always returning '1'. I have tried Serial.print to debug the value of analogVal. Even if the value is 255 it returns 1. Is it a bootloader problem?


texts:
What does this op amp circuit do?

Do I understand correctly that this is some sort of divider?
What is the output of the op amp if 5v is on the inverting input?

Full circuit here:

RM: As somebody is liable to ask. This circuit is used here under the permitted category of "fair use" for the purposes of training and instruction.


texts:
I am familiar with the bootstrap circuit and its design procedure. The steps involve:

a) Figure out the Qg of the MOSFET at the Vgs you plan to operate (for instance Vgs=15V, Qg=150nC). Next, figure out the current consumed by the gate driver IC itself (for instance 3mA). Also know the frequency of the PWM input (fs=100kHz, ts=10us) and the duty cycle (D=90%, Ton=9us).

So the total charge required by the boot strap cap. would be: 150n + (3m*9u) = 177nC

b) The next step involves calculating the value of the boot strap capacitance (CB), based off of UVLO. Lets say we don't want the voltage to droop below 14V.

CB = 177n/(15-14) = 177nF

c) Finally, make sure that the CB is replenished with 177nC of charge in 1us (i.e. D'*ts). Therefore the current demand on the source (the source which is connected to the bootstrap diode) is:

I = 177n/1u = 177mA

Now, as shown in the figure below, there is also the option to use an isolated DC-DC converter instead of the boot strap diode:

Most of the SMD/SMT DC-DC converters I have come across (Mouser list of isolated dc dc converters) are generally rated at 1W or 2W. If you were to select one which has an output voltage of 15V, then you would get an output current of about 66mA. Which is not good enough for the calculations listed above. Of course in this case, there is no scenario where the cap. C1 has to bear all the load by itself (as the DC-DC converter never disconnects from the cap., unlike the bootstrap topology)

My question is:

1) If a DC-DC converter of 1W is selected (i.e. Iout=66mA), and the same MOSFET with Qg=150nC is selected to operate at 100kHz, D=90%, Will the circuit operate? (Also don't forget the gate driver consuming 3mA)

The DC-DC converter can supply a total of 66mA for all of the ts=10us, so Q=66m*10u = 660nC. This is more than enough! But is it that straight forward?

2) Also what are the design constraints on C1?


texts:
This question has already been asked on this link but I cannot comment there. I want to run my STM32F4DISCOVERY board from external power supply, but it does not run as it should. As specified in the link, the led LD1 is red-blinking, and my code is not running. I updated the firmware of the board as suggested in the answers:

Is there something else I should do ? Some hardware modification maybe ? Currently there are jumpers on CN3 and JP1 connectors. Thanks in advance


texts: What is the opposite of the Power Supply Rejection Ratio?

texts:
The PSRR of a device is the dB measurement of the power supply noise rejection. In my case, I have an LP5907 LDO with a PSRR of ~80dB, which would mean that if I have 10dBm of powerline noise on the input, I'd expect it to be reduced to -70dBm on the output - which is great!

But I'm actually more concerned with the noise being generated by the device fed by the LDO, and how much switching noise will end up feeding back into the system. Is there a device characteristic that describes its susceptibility to downstream noise sources?


texts: AtTiny85 128khz clock and power consumption

texts:
I am wondering about the Tiny85 power consumption and methods.
I cannot find answers for the following questions in the datasheet, maybe I will find it here..

The 128Khz internal watchdog clock should use less power than the 8Mhz clock [choosing 128khz will not use the 8Mhz clock, which save power].
I am assuming 8Mhz with prescaler of 64 (gives 128khz) will be waste of power, right? I can just use the 128khz internal oscillator?

Theoretically, can I use the clock prescaler even with the 128Khz clock (CLKPR register)? If yes, I can set it to /256 = 500hz clock, which should save me some more power. In the real life I cannot do it, I need ADC, which the minimum prescaler is 2, so 128Khz will give me 64kHz at max, while the range of the ADC is 50-200khz which fit well. Am I right?

Another aspect is the output PORTs. Setting all of the output ports to be input should save some more. but Should I set them to 1 or 0 (in terms of pull up resistance) to save more power?

And last thing I need to clarify - Before powering down, I am disabling ADC in order to reduce consumption. I am setting ADEN to 0 on ADCSRA.
I read about PRR register on the datasheet and I saw I can shut TIMER0, TIMER1, USI, ADC.
Will it change the power down consumption?
Will PRR ADC shut down differ than ADCSRA disabling ADC?

Thanks.


texts: Signal parameters compatibility between DragonFly 1.5 & old amplifier

texts:
I have DragonFly 1.5 Black (spec: http://www.audioquest.com/wp-content/uploads/2016/04/dragonfly-spec-sheet-darktheme.pdf). I'd like to connect it (via minijack - 2xcinch cable) to the very old amplifier Denon PMA-960 (spec: http://audio-database.com/DENON-COLUMBIA/amp/pma-960-e.html).

Could you please tell me (because I don't have enough technical knowledge) if the signal parameters of Dragonfly's (1.2 V or 2.1 V - depends on version) output minijack (in whole volume range) are within the tolerance range for the AUX (line-in) connector of the amplifier and "line-level" specification?

I don't want cause damage devices.

Can I also connect notebook (Dell E5450) to this amplifier?

I will be very grateful for your response.


texts: How to determine the pole number or synchronous speed of an AC motor from its rated RPM?

texts:
Trying to to determine the pole number or synchronous speed of the following AC motor from its rated RPM. Here are the details:

http://www.vanbodegraven.nl/en/products/ac-motors/asea-mbg-200-m-60-6/

What is its synchronous speed(stator winding frequency) and pole number?

A VFD is being used


texts: Li-ion battery cell balancing statistically unnecessary when many cells are in parallel?

texts: Lithium ion batteries packs need to be balanced because of a small random voltage difference for each section in series, that may cause the voltage levels in a pack to diverge over time, right? So if you had a large number of cells (<40) in each series section wouldn't it be unnecessary to have balancing circuitry as the voltage difference of each series section would be extremely small due to the large sample?


texts: Using a lower pot value for motor bidirectional controller

texts:
I'm looking to make a bidirectional motor controller. I would like to use the following diagram. What values should the resistors be in order to use pot(S) of smaller value than 100k and the circuit still work?
Can someone please explain the formula when using different pots value.


texts: Transformer and a relay in series - but function like in parallel, but not exactly

texts:
I've been doing some planning to build a home automation system on top of the existing power infrastructure of my house.

The first thing would be making my light switches smart. My original plan is to replace the current switch with my own (push switch) that would talk to a microcontroller that would in turn switch a relay and report the status to the control center. Powering the 3v microcontroller and a 5v relay would be done by a 220vac to 5vdc 3.5W buck converter. But the problem is that behind a single pole switch lies only two wires, Hot and Switched.  Most boxes don't have the Neutral present.

I can't connect the converter and a relay in series because the microcontroller would not get any power if the light is off, and if I connect them in parallel the light would be constantly on, regardless of the relay status.

What is left for me to do?

Schematics: https://www.dropbox.com/s/0tdb1mkmnwny6n6/scheme.jpg?dl=0


texts: What's the cheapest way to make a dithered-input ADC?

texts:
I know that some of these PICs have ADCs built in, and I may want to use that.

I am wondering if there is a way I can effectively dither the input to a low-bit (like 8 bits) ADC with the fewest parts (like no unnecessary op-amp) and all cheap and widely-available vanilla-flavored parts.

The voltage measured might be DC or very low frequency, likely always less than 10 Hz.  The effective sample rate might be as low as 50 Hz, but this is after averaging the 500 kHz samples from the ADC.

The ADC was just randomly picked because it looked cheap.  The Zener was chosen to be less than 5v breakdown.  The resistors are guesses.

My questions reside among the Zener and associated resistors.  What's a good cheap Zener to use for a noise source?  What kinda r.m.s. AC noise output can I get from some cheap Zener?  I want this voltage to be somewhere around the LSB voltage of the ADC which is VREF\$\cdot 2^{-8}\$ or VDD\$\cdot 2^{-8}\$  I do not want to need more than +5v and GND power supply.

The idea is to get, cheaply, much better than 8 bit precision, by dithering and averaging.  Anyone do this before?  What can I gain from your experience?

simulate this circuit – Schematic created using CircuitLab

Denouement:

Just FYI: I finally found a reference of someone measuring noise output of zener diodes.  It looks like the noise from a zener in breakdown is about 1.5 µV which is far less (about 80 dB) than the 19 mV LSB and won't do much to dither unless one were to amplify it, which makes it less cheap (and I wanted to do this on the cheap).

So Tony EE "RocketScientist", that is the reason the circuit will "certainly not" work.  And you didn't say a word why that's the case.


texts:
Here's a really nice multi-wire splicing connector:

http://www.wago.us/news/5019.htm

http://www.wago.us/images/222415_PR.jpg

I'm using it for power distribution for a quadcopter:

http://eastbay-rc.blogspot.com/2011/03/update-wago-connector-for-power.html

The specs say it has a listed capacity of 600V/20A.  If I am using it for 12V apps, can I go higher on the amperage?  i.e., are these rating in terms of total current flow?


texts: how to choose level shifters for serial / UART

texts:
I have so far been using some MAX3323EEPE chips for shifting between 3.3V and 5V logics on serial / UART communications. This is quite some stuff to solder on a PCB, and the chip is a bit expansive. I only do quite vanilla communications, such as up to 57600, absolute max 115200 baud rate.

Would this kind of shield:

https://www.adafruit.com/product/757

do the trick?

And this kind?

https://www.adafruit.com/product/395

Edits

Edit 1: typical use: I am thinking about having a project built around a 3.3V micro-controller, but I will need to be able to talk to some 5V logics stuff too. I will have a 5V step-up converter on the design, so getting 5V is not an issue. Typically, I will need to talk to a RockBLOCK 9603, which seems to be rather 5V than 3.3V ( https://www.rock7.com/products-rockblock-9603 though not completely clear to me if it would be ok to power with 5V and talk through 3.3 logics level; but other things will definitely need 5V logics levels anyways, so good to put on board).


texts: Why would clipping a wire cause a bomb to explode?

texts:
There are a lot of movies and video games that depict defusing bombs, most of which boils down to picking the right color wire.   Something like this:

Now, that's a part I don't understand.

simulate this circuit – Schematic created using CircuitLab

I'm not  very familiar with circuitry and electrical engineering, but I assume this would be the place to ask it.  I'm confused as to how clipping a wire would cause a bomb to explode.  I assumed that if you clipped a wire, there'd be no connection from the switch to the bomb, so it wouldn't explode, but apparently, in a lot of movies as well, clipping the wrong wire leads to dangerous things.

simulate this circuit

Is this a realistic scenario? I really don't understand why clipping a wire would cause a bomb to explode. Rather, shouldn't it "defuse" the bomb?


texts: How are the gain and corner frequencies calculated for this speech bandpass filter?

texts:
This speech bandpass filter circuit appears in the TI OPA344 datasheet.  It says "G = 100" and passband is 300 Hz to 3 kHz.  How is the gain and corner frequencies calculated from the various component values?  I'd like to try this circuit but I only need a gain of 5 and I might want to tweak the passband.

I think I see that R7 and C2 form a first order low pass filter with a corner frequency of 3120 Hz.  And I believe R6 and R5 produce a gain of (1 + R6/R5) = 6.  But I don't understand the rest of the circuit.  Where is the rest of the gain and the high pass filter?


texts:
Back when I was younger, I used to take apart the old disposable cameras I'd take to camp to have fun playing with the parts and doing a bit of exploring.  One year I ended up with a camera with a flash, and got a bit of a surprise.

After having removed the cardboard I took a moment to look it over, with the thumb of one hand resting along the AA battery on the bottom.  As I'm finishing my evaluation of the piece, my index finger from my other hand touched the top of the flash, which sent a current up one arm and back down the other, setting off the flash.

This caught me completely by surprise, because I'd always thought batteries only conducted if there was a complete circuit between the poles, and even holding a battery by both ends at once I've never noticed a charge before.  What exactly happened here?


texts: Voltage Output of a Current Source in Parallel and in Series with a resistor

texts:
Hi All,

I imagine this is a pretty basic question to ask but I'm struggling to get my head around this. I'm trying to find \$V_{out}\$ of the circuit above.

Now I understand why \$V_{out}\$ can be \$-g_mV_{GS}R_2\$ (as taking the Norton equivalent of the circuit on the left just gives a current source of \$-g_mV_{GS}\$ in series with 0 resistance). Thus this current causes a voltage drop over \$R_2\$ which gives \$V_{out}\$.  (This is of course equivalent to saying the output from a voltage source does not change if it is in parallel with a resistor).

What a fail to understand is how the \$V_{out}\$ could not be \$g_mV_{GS}R_1\$. Assuming the bottom of the circuit is grounded, surely there must be a voltage drop due to the current from the current source over \$R_1\$ ? Due to the fact the circuit is parallel, surely this voltage drop should be necessarily equivalent to \$V_{out}\$ ?

I'd appreciate any advice on how to best understand this problem & any tips and tricks you may have for the future!

Many thanks!


texts: Add a LED and a resistor to a working circuit

texts:
We found, with my 6 y.o. kid, a 9V battery and an old CPU fan power supply fan, and we were happy to see the following circuit 1. working.

Then he asked: "Can we add a switch and a LED?" For sure we can, but how... I'm not sure. Among 2., 3., 4., which one is the more appropriate? How to calculate the relevant resistor value?

Note: Please correct me if I'm wrong but I think we can assume this standard LED we found has a forward voltage ~ 2V. How to use this to derive the resistor value in case 2., 3., 4.?

Note 2: In circuit 1., I measured, with a multimeter, a voltage of nearly 9V (a little bit less when motor was running), and a current of ~ 160 mA, thus I estimated the "equivalent resistance" is around 55 Ohms for the fan. (I don't know if this concept is correct).


texts: Stability in control theory and electronics

texts:
In control theory, if the impulse response of a system dies out then the system is stable.

In electronics, Bode plot usually uses the see the gain and phase margins and determines the stability of a system.

Does the stability in the two fields mean the same? Also is there any relationship between them?

Update:
In control theory, stability is defined as a measure of the tendency of a system's response to return to zero after being disturbed. So does the definition is also applied in electronics (for example OpAmp) and how to test it (say OpAmp) using this definition?


texts: Is it possible to only utilise SMBus on PCI Express 1X?

texts:
According to the Wikipedia page on PCI Express, the PCI-e 1X slots have 18 pin positions on two lanes (so 36 pins) and positions 5-9 represent SMBus and JTAG.

I'd like to hook up a µC as an SMBus (essentially I²C) device, and I understand the additional message protocol requirements, but am not exactly sure which pins I'm meant to be interfacing with.

I can see pins for SMCLK, SMDAT, TCK, TDI, TMS, TRST, TDO, WAKE, PERST, PRSNT1, PRSTN2, plus a bunch of PCI-specific stuff. I know that the PRSNT pins have to be shorted, and that there are +12V and +3.3V supplies for the device, but the rest is a bit confusing. Normally with I²C I'd be thinking SDA and SCL, but the pins I'm seeing here look more like the kind of interface I'd expect from SPI, with separate input and output data pins and device select. Is this the JTAG bit, and am I meant to just be looking at SMCLK/SMDAT?

So, my question is two-fold:

Which pins should I be concerned with?
Do I have to do anything more than jumper the PRSNT1/PRSNT2 pins to get the device registered? That is, can I safely ignore everything but the SMBus interface? In fact, do I even need to mark the card as present with those pins, or is it just for devices that utilise the PCI bus?

Apologies if this seems a rather trivial question - I'm much more adept with software than I am with hardware.


texts: Attaching two identical PSRAMs to the same set of signals

texts:
I have an ARM microprocessor connected to an FPGA through one 47 pin memory bus. Also, two identical PSRAMs (datasheet available here) are connected to the FPGA through 65 pins (47 for first PSRAM + 16 extra data pins for the second PSRAM + 2 extra control pins for the second PSRAM).

For emissions testing, I would like to drive both PSRAMs at the same time, and at full speed. However, to drive both PSRAMs independently at the same time, I would need 65 control pins between the ARM and the FPGA, but I only have 47.

I was thinking that I could drive both PSRAMs at the same time and in exactly the same way by routing the 18 extra pins for the second PSRAM to the first PSRAM.

However, there are two potential problems I am seeing:

The WAIT output signal for both PSRAMs might not behave the same way, and I do not see an obvious way to combine the two WAIT signals into one.
When the ARM makes a READ request, there is a possibility that both PSRAMs will not return the same value on their data buses, which means that the combined data bus will be driven by both the PSRAMs in different ways.

Are there other problems I haven't considered with routing the pins of two different PSRAM to the same controller? Are there solutions to the two problems above?


texts: Interpretation of the graph of accelerometer

texts:
I have plotted the raw values of my accelerometer in gnuplot,
and the acceleration in the dimensions of x, y and z are as follows...

The accelerometer sensor is in a steady position, my question is.

Why the values of Z are always in 1.


texts:
I'm using Arduino Uno with a 12V RGB Signal Amplifier and a 12V RGB LED strip. 12VDC is supplied to the amplifier.

However the LED strips does not light up whether the PWN pins are set to either 0 or 255.

   analogWrite(ledPinR, 255);
   analogWrite(ledPinG, 255);
   analogWrite(ledPinB, 255);

When set to 255, the OUTPUT R,G,B pins have a voltage of 6.3 V to 8.6 V, while the INPUT R,G,B pins are about 4.7 V.

The OUTPUT pin voltages does not change whether the INPUT pins are at 0V or 5V.

The RGB strips light up when I connect the POWER - terminal to any of the OUTPUT R,G,B terminals.

What can be done to allow the Arduino to light up the LED strips?


texts: Use female Apple lightning connector for charging LiPo

texts:
I am creating a electronics project powered by a 3.7 V LiPo Battery. I want to make it chargeable via Micro USB or Lightning cables.

Is it possible to buy female Lightning connectors and is it allowed by Apple to use them?


texts: Difference between dynamic resistance of diode and resistance of PWL model of diode

texts: What is the difference between dynamic resistance \$r_{d}\$ of a diode and resistance \$R_{D}\$ of piecewise linear model of a diode? The book "Microelectronic Circuits - Analysis and Design - Muhammad H. Rashid (2nd Edition)" says that \$R_{D}=r_{d}\$, but it seems so strange. In fact, to get \$R_{D}\$ it is necessary to drawn a straight line that passes always through the operating point Q and the point \$\left(V_{threshold},0\right)\$. Whereas to get \$r_{d}\$ it is necessary to drawn a straight line that passes through the Q-point and that is tangent to the diode characteristic. These two lines are not the same.


texts: Here the zener voltage of the zener diode is 3.3V and base to emitter voltage drop is 0.7V. What is the voltage across the load resistor and how to find it?


texts: Why am I getting odd inductances from home made inductor?

texts:
This question is related my my previous question: What to do about very hot planar inductor?

What I'm trying to do

I am trying to make a planar inductor (made from the tracks of the PCB, and surrounded by a 2 part a ferrite core). According to the datasheet of the ferrite core, the AL value is 1700nH, which means that with 12 turns around the core, I should get 12x12x1.7 = 244uH.

The problem

However, when I measure the inductance on my LC meter, it reads only 1.8uH. What's stranger is that if I create an inductor with the same core, but using stranded wire, and only 10 turns, I get 46uH!

I measured the resistance of the PCB tracks, and it's 0.25R, just as it should be, so I don't think there's a short in there.

My questions

What's going on? Is the AL value not sufficient for calculating inductance? How could it be that fewer turns gives a much higher inductance? Is the stranded wire massively better than PCB trace?


texts: How to control a 12V H Bridge circuit with a 1.5V polarity switching signal voltage?

texts:
let's start with apologizing for my lack of knowledge and subsequent mistakes, I'm just getting started.
The Situation
I have a remote receiver (from a kids toy) that outputs between 1.45-2V when triggered. The polarity of this output also changes (used to control motor rotation). I would like to use this output as an input trigger for activating a 12V circuit.
This input voltage is obviously too low to directly control the relays (coils require 0.89A @ 9V / 0.66A @ 12V) (and the current draw from the 12V motor would be way to high for the receiver circuitry - max 6A).
I am able to control the direction of the 12V motor using 4 12V relays in an H-bridge configuration by manually triggering the appropriate relays, i.e forward = trigger Rel1 & Rel2, take note that the relay coils are not polarity sensitive.

Problem 1

How do I boost the output from the receiver to a voltage high enough to trigger the relays? Keeping in mind that the polarity switches. As far as I could tell, a simple DC to DC step up would only work if the input polarity remains constant. Perhaps another H bridge consisting of a few diodes and transistors could rectify the polarity before pushing into the step up converter?

Problem 2

If I do manage to get the voltage up, how do I correlate the original polarity to which relays to close, due to the relay coils not being polarity sensitive?
I'm trying stay away from microprocessors and motor control boards so as to get a better understanding of the logic involved in this type of circuit. So I'm not so much concerned with the easiest way of achieving the desired outcome.
Any advice or steering in the right direction would be appreciated.


texts: ADuC702x MCU bandgap voltage reference question

texts:
I have recently started using the ADuC702x MCU family.
I plan on using the analog to digital converter that comes with the MCU. The datasheet states that there is an internal 2.5V that it uses for its bandgap voltage reference for its ADC. I would like to use 0V to 3.3V for my ADC application.

On the datasheet, page 50 in the Band Gap Reference section, it states that an external reference input on the Vref pin can be used but must be able to overdrive the internal 2.5V.

At first glance, I figured I could simply connect to my 3.3V rail to Vref to "overdrive" it and program REFCON = 0x00. However, the term "overdrive" has bugged me. Furthermore, I have done some research on this and all online schematics show using the internal 2.5V reference. If it was easy to change Vref, I figured I'd see something other than 2.5V being used.

Has anyone ever used the ADuC702x family? Any help and guidance would be appreciated. Thanks!

Datasheet Link:
http://www.analog.com/media/en/technical-documentation/data-sheets/aduc7019_20_21_22_24_25_26_27_28_29.pdf


texts: Design help! -- Play a pure tone into a mic and depending on its frequency a specific LED will light up

texts:
I'm still new to electronics and am making this in order to learn more about circuit design and filters. I do not want to use microcontrollers.  I want a purely analog solution.

I'm trying to make a frequency detector that detects between 5-10 different frequencies. There will be a mic, an amplifier, a set of bandpass filters, and  an LED that corresponds to each filter. The goal is to play a relatively pure tone into the mic, and have a certain LED light up which will be telling of the frequency of the tone. I want each filter to have a range of around 100Hz. The ranges will be 100-200,200-300,300-400,400-500,600-700 and maybe some more.

If I play a tone of 250Hz, the LED that correspond to the 200-300Hz range should light up.

The method I thought of is to have comparators after the BP filters so I can cut off the frequencies I don't want. The output of the comparator will be connected to the LED. I would much rather have the filter do the cutting off rather than having to use comparators,  but won't I need a very high Q filter so that for frequencies immediately past the cutoff range the LED is completely off rather than being dim? How can I do this without using comparators?

My proposed flowchart of the circuit is mic->band pass filter->amplifier ->rectifier->low pass filter->comparator(maybe)->LED

Regardless of whether I use comparators or not, I will need to know the input voltage so that I can amplify it to the right level to light the LED. How can I do this if when I play a tone in the electret mic, the output voltage will change depending on how loud it is and how close to the mic it is. How can I take this into account when I design the circuit? I looked up automatic gain control schematics, but it looks a little bit too involved for my liking and would add a lot of complexity to the project. Is there any other option?

What kind of band pass filter do you guys recommend? I know there are two main categories, passive and active, but I don't know enough to judge which one will be best suited for this application. I'm leaning towards active because then I won't have to use inductors which are expensive and could possibly cause interference if they aren't shielded properly. From what I've read, active filters are easier to design and are less dependant on the load connected to it, which is a plus for me since I'm a beginner.Also since active filters have a 'built in' amplifier I won't need to make a separate amplifier. Anything I'm missing?


texts: 7-segment driving circuit not working as expected

texts:
I have designed and built the following 7-segment driving circuit utilising an Arduino Micro in order to try and further understand electronic circuit design:

simulate this circuit – Schematic created using CircuitLab

When turning it on and applying a HIGH voltage to the \$\text{LT}\$ and \$\text{BI}\$ inputs and a LOW voltage to the \$\text{LE}\$ input, regardless of what BCD code I supply to the CD4511BE BCD to 7-segment display driver the LED display just flashes while displaying \$0\$. If I set the \$\text{LE}\$ input to HIGH then the LED display no longer flashes but instead just displays \$0\$.

Here is the test code for the Arduino that I am using:

void setup()
{
  pinMode( 2, OUTPUT );
  pinMode( 3, OUTPUT );
  pinMode( 4, OUTPUT );
  pinMode( 5, OUTPUT );
  pinMode( 6, OUTPUT );
  pinMode( 7, OUTPUT );
  pinMode( 8, OUTPUT );
}

void loop()
{
  digitalWrite( 6, HIGH );
  digitalWrite( 7, HIGH );

  for( int i = 0; i < 10; ++i )
  {
    digitalWrite( 8, LOW );
    digitalWrite( 2, i & 0x0001 != 0 ? HIGH : LOW );
    digitalWrite( 3, i & 0x0002 != 0 ? HIGH : LOW );
    digitalWrite( 4, i & 0x0004 != 0 ? HIGH : LOW );
    digitalWrite( 5, i & 0x0008 != 0 ? HIGH : LOW );
    digitalWrite( 8, HIGH );
    delay( 1000 );
  }

    }

Further Information: The following code works as expected:

void setup()
{
  pinMode( 2, OUTPUT );
  pinMode( 3, OUTPUT );
  pinMode( 4, OUTPUT );
  pinMode( 5, OUTPUT );
  pinMode( 6, OUTPUT );
  pinMode( 7, OUTPUT );
  pinMode( 8, OUTPUT );
}

void loop()
{
  digitalWrite( 6, HIGH );
  digitalWrite( 7, HIGH );

  digitalWrite( 2, HIGH );
  digitalWrite( 3, HIGH );
  digitalWrite( 4, LOW );
  digitalWrite( 5, LOW );
  digitalWrite( 8, HIGH );
  delay( 1000 );

  digitalWrite( 8, LOW );
  digitalWrite( 2, HIGH );
  digitalWrite( 3, LOW );
  digitalWrite( 4, HIGH );
  digitalWrite( 5, LOW );
  digitalWrite( 8, HIGH );
  delay( 1000 );
}


texts: Reducing the sensitivity of a PIR sensor?

texts:
I have several standard BISS0001 based PIR sensor modules, but lack any sensitivity trim pot.

I am hoping there might be a way to reduce range/sensitivity to a very small field. Currently they are detecting motion about 15-20 feet away.

Does anyone know of a way to reduce the field as low as maybe a 1 foot radius?

I am using them with an Arduino Mega 2560 or an Arduino Uno.

I have tried placing various objects / films in front of the sensor.

Running the sensor through a tube (cardboard or PVC) seems to effectively reduce the sensor to a very narrow beam of detection, however I also need to reduce the overall range, as even with through the tube the sensor fires off at 15-20 feet away.  I have tried placing plastic wrap or the reflective static free plastic that electronics are shipped in over the end of the tube, these do not seem to do the trick.


texts:
I want to create a PCB with some traces on the solder layer, so I can reinforce them with tin.

Those traces will use AC current and about 5 amps. So I want to create some traces with 3mm wide and tin above.

I just see options to create traces on top layer and bottom layer. How can I create a rule to create those traces on solder layer? I am not sure which layer I need to choose neither.


texts: BNC cable to composite video cable conversion

texts: I currently have a robotic cutter which has a BNC female connector connected to a composite video cable. I want to remove this extension cable and simply terminate the cable to a composite video connection, is this at all possible?


texts:
When calculating an ADC or DAC ENOB, do you use SNDR or SINAD, SFDR, SNR or SDR or something else ?

I have see all used in calculating the ENOB, so which one is correct ?


texts:
Is there a way to estimate how fast a channel changes with respect to time in practical applications?
While evaluating doppler effect for a user we use the frequency at which the channel changes. How is this frequency different from the carrier frequency we use to transmit a signal.
For eg if we have a wireless system operating at 935MHz with a Bandwitdth of 2MHz and Data Rate of 2Mbps.
How fast should I predict the channel to change?


texts: What is meant by front and back pitch of an armature winding?

texts:
I searched the internet for these definitions and found a common definition in all websites:

Back Pitch-
A coil advances on the back of the armature. This advancement is measured in terms of armature conductors and is called back pitch. It is equal to the number difference of the conductor connected to a given segment of the commutator.

Front Pitch-
The number of armature conductors or elements spanned by a coil on the front is called front pitch.

I din't get these definitions. I don't understand what is meant by "back" of the armature.
Can you please explain me the two definitions?


texts:
Using Vivado 2015.2, VHDL.
Got a warning "[Synth 8-1565] actual for formal port b is neither a static name nor a globally static expression"

ADD1: Adder_32_33
PORT MAP (
A => a1,
B => a1&"0", -- warning here
CLK => clock,
S => s1
);

Sim works fine.
Can this warning be ignored ?
Is there any solution besides adding a new signal ?


texts: What are the important specs to look after for IGBT replacement?

texts:
I have a MC2100ELS-18W motor controller and after inspection found that the IGBT is shorted, the part number is IRGPC40K
I suppose this is a discontinued part and I do not want to buy from China and want to find a replacement.
I have no experience when it comes to IGBT and I am not sure about all the important specs to look for.
I have been able to specify a replacement and I want some advice if it is suitable or not
AOK30B60D1
and
AOK40B65H2AL
I was looking for the following:
Vce, Vge, Ic, Pd, Input Capacitance, Gate Charge, Turn-On DelayTime, Turn-Off Delay Time
I am really not sure if I should look for something else or not and whether if those specs should be exactly the same or not, some of them are a little bit higher like power ratings and voltages and other are lower like Charges, Capacitance and Delay times
One thing that I am not sure if it will change anything or not that the old part has no diode integrated and the new replacement has integrated one and I suppose that diode specs should also be respected !
This Controller is using IR2127 IGBT Driver and the motor is rated for 130V DC and 2.75KW continues Duty
My Question is is there a problem If some specs are more or less the original part specs?
For example, the new replacement (Input Capacitance, Gate Charge, Turn-On DelayTime, Turn-Off Delay Time) are lower than the original part, would that make a problem?


texts: How can I use the presence or non-presence of an 120VAC input to actively discharge a bias power rail?

texts:
I'm designing a power supply that has an input of 100VAC to 300VAC.  On the primary side on the main transformer, I have a 15V rail to power the control chip (a FAN6920) and a gate drive chip (a FAN7382).  On this 15V rail, I have roughly 400uF of capacitance.  Because of this amount of capacitance, the hiccup time of the supply is about 10 sec.  That's the time it take for the 15V rail to decay down to about 5V, at which point the control chip will attempt to start back up.  This is acceptable during an actual fault (e.g. an over voltage condition on the output or the output shorted), but this hiccup time is also present when turning the line off and then back on within that 10 seconds.  The supply is used to power lights, so as you can imagine, no one wants a potential 10 second delay when they hit the light switch.

To that end, I'm trying to figure out a way to design a circuit that senses whether the AC line has gone away, and if so, to pull down the 15V rail quickly, while at the same time not impacting steady state operation.

simulate this circuit – Schematic created using CircuitLab

My first attempt at this is above.  This idea is that C1 will charge to 10V when the line voltage is applied, holding M2 on.  Holding M2 on will hold M1 off.  At the same time, C2 is charging to 10V.  When the line voltage is disconnected, C1 discharges much quicker than C2, allowing M2 to open up, and allowing C2 to change the gate of M1, turning it on and rapidly discharging the 15V rail through a 10 ohm resistor.  However, in practice, C1 doesn't discharge nearly quick enough.  It maintains enough voltage to keep M2 on for several seconds, so it doesn't really buy me anything (and also, the charge of C2 decays enough that it can't turn M1 on at that point, anyway).  I can't change the time constant of C1 and R2 by much because the voltage across C1 will start drooping significantly when the line crosses 0V.

I am not tied to this topology by any means; this was just my first pass at a solution.  And while I've tried a few other things, nothing has really worked, so any suggestions would be appreciated.  Thanks.


texts: What is the practical use of a phase response plot?

texts:
When looking at the response of a digital filter, typically the magnitude and phase response of the filter is plotted. While the use of the magnitude plot is obvious, as it shows how each frequency is amplified or attenuated, I'm not as clear on what the use of the phase plot is. This is especially this case for linear phase response filters.

So, what is the practical use of looking at the phase response of a filter?


texts: Which are the safety recommendations for soldering?

texts:
I was reading about tin alloys for electronics soldering and found it it has about 40% of lead in composition. Lead, everyone knows, it's very dangerous to breathe due to being a heavy metal. Also, I found some recommendations using the combination of an exhauster and a respirator when working with soldering. Is there any international regularization of which respirator type should I use? If not, which type do you recommend? Beyond this, is there any additional safety equipment recommended?

For economics reasons and for better soldering resistance, I've already discarded Pb free solder reflow.


texts: Can we apply Nodal Analysis to non planar circuits?

texts:
Can we apply nodal analysis to non-planar circuits the same way we apply nodal analysis for planar circuits?

If yes how do we systematically apply nodal analysis?

If no is there any alternate for this?


texts: Iterative simulation of RC low pass filter, strange correction required

texts:
To get further understanding in how iterative simulators work, like circuitJS for an example, I decided to make my own of a simple RC low pass filter.

The voltage I am interested in is the one across the capacitor, it can either be calculated with the following formula:

\$V_C=V_{E}(1-e^{-\frac{t}{RC}})\$

Or it can be approximated by this algorithm... that I scrambled together:

VC = 0;
for(int i=0;i<N;++i){
  VC += time_step*(VE-VC)/(R*C);
}

time_step would be the time in seconds between the updates of the simulator. With this algorithm, the t is the product of time_step and N. It is a simple first order digital LP filter.

So I implemented that algorithm in google sheets to see how good it was. And it was fairly correct.

This is the data that was used:

As you can see, it's not a perfect fit.

If I however modify the algorithm a little bit to this:

VC = 0;
for(int i=0;i<N;++i){
  VC += alpha*time_step*(VE-VC)/(R*C);
}

and set alpha to 0.824, which comes from the ratio between the correct value and the iterative value at t = 10 µs. Then I get a perfect match with 0 error.

I calculated alpha = 0.824 from \$\frac{RC}{\text{time_base}}(1-e^{\frac{-\text{time_base}}{RC}})\$ with R = 25, C = 1, time_base = 10

Why do I need to add that correction multiplication "alpha" when I am iterating?

Extra information: As time_base goes down to 0, alpha goes to 1. In other words, as I step through finer and finer steps in time, the less the error becomes.


texts: Can I replace a 27.12MHZ by a 13.56MHZ Xtal on PN532

texts:
I have a prototype of NFC reader which is attached to my Board. But it seem it doesn't work ... the only change I made was the Xtal because I don't find 27.12MHZ.

Some people told me I can replace it if the hz was a multiple. The fact it don't work as expect. Is it normal ?


texts: How to change adc sampling time in STM32 to 20 Hz

texts: I want to change the sampling rate of my STM32F303RE to 20 Hz. Is this possible with a ADC clock with 8 MHz and without a HAL_Delay() function?


texts: How to share a variable between ISR and main-code?

texts:
I'm working on some embedded software and I ran into a problem and I cannot figure out why this block isn't working.
I set up interrupts to for several buttons, including a mechanical encoder. I used breakpoints and debugging to determine the code flow. The block that isn't working as it should is super simple.
uint8_t calcEncoderValue(void)
{
  int encVal = 0;

  if (gpio_get_pin_level(ENC_A))
  {
    encVal = 2;
  }

  if (gpio_get_pin_level(ENC_B))
  {
    encVal = encVal + 1;
  }

  return (uint8_t) encVal;
}

The code goes into the first if statement when A is HIGH, but value for encVal remains 0.
Coding doesn't get much simpler than this block, so I'm absolutely stumped. Does anyone have any idea what is going wrong here?


texts: Can I use more diodes for lower voltage drop and higher current?

texts:
The problem is simple: I have bought an UBEC, which should accept 7,6V from my battery and give me 5V to power my electronics. But the one I bought does not give me 5V, but 5.3V - that could cause trouble as I am going to power a Raspberry Pi as well, which could be damaged by this voltage...

So I tried using a diode to drop the voltage a bit. It did indeed, but I am having trouble finding a diode, that would drop it maximally for 0.5V at 3A, so that the drop is not too big (Raspberry Pi demands 4.75V - 5.25V, if I remember correctly and I'm planning on using more TTL electronics, like a webcam, which could be sensitive to input voltage as well).

The question is: Could I use more diodes in parallel to increase the maximum current and decrease the voltage drop or would this not work? I yes, could anyone recommend a good diode to use? I need to have maximum current at least 3A (for some motors and such).

I was thinking of using these: http://www.gme.cz/dokumentace/223/223-001/dsh.223-001.1.pdf

Thanks!


texts: On an isolation transformer, were do ground pins go?

texts:
The outputs from transformer have a ground.
Is output ground earth ground?
Isn't the whole point for those transformers not to provide earth ground potential?
Example:


texts: Evaluation of the primary inductance of a transformer whose core is saturated

texts:
I would like to know if it is possible to theoretically estimate reasonably the primary inductance of a transformer when its core is saturated.

Otherwise, what is the best way to do it by measurement?


texts: How to decide dimensions of PCB heatsink?

texts: I am using MCP73213 IC for charging my 2S Li Ion battery.  I want to use this IC for 1 ampere charging during constant current charge cycle.   My specifications are as follows. Input source voltage : 9 volts(10 % accurate) charge current : 1 ampere during constant charging cycle  Max power dissipation for such application is as follows : (9.9 volts -6 volts)* 1 ampere = 3.9 W Thermal resistance of IC : 62 C/W So rise of temperature during max power dissipation : 62*3.9 = 241 centigrade.   But according to datasheet, IC will die at 150 centigrade. Datasheet of MCP73213 : http://ww1.microchip.com/downloads/en/DeviceDoc/20002190C.pdf  I would like to place PCB heat sink below MCP73213 IC to allow power dissipation. What should be the dimension of PCB heat sink. I am really confused. Please help me in this regard.


texts: How do I find source of vibration from a mechanical source outside of my home?

texts:
My problem is vibration from a mechanical source outside of my home. I think I have found the source (machinery at a legal marijuana grow op) and need to prove it to get an injunction at court.

I don't know if there is direct mechanical transmission (1 - 80 Hz) or if ground or air noise is causing my house to resonate (4 - 8 Hz). So I'm looking for a tool, probably an oscilloscope, to use with an industrial accelerometer to find direction to source. I'm also looking for a spectrum analyser to use with an infrasonic microscope to detect infrasonic noise and get a frequency signature.

How do I select a DSO/SA that has frequency response from 0 - 80 hz? My budget is very limited, as this is just a one time use.

If anyone has a better idea let me know!


texts:
I'm trying to use an H11AA1 (datasheet) optocoupler to test when my doorbell is pressed (I'm in an apartment building):

simulate this circuit – Schematic created using CircuitLab

It worked when I first tested it, but then it stopped working less than a day later. I have a second optocoupler (which I bought with the idea that I would almost certainly break the first one somehow), and if I swap it in it works. The input part is supposedly rated for 230VAC, so I don't think the issue is there.

I've disconnected it all for now out of fear of breaking the second optocoupler. What did I do wrong?


texts: Voltage controlled connection of two signals that are at higher voltage than the control voltage

texts:
Given are two signals A and B. I want to control the connection between them by a signal C. However, signal C is a logic signal with a voltage of 3.3V for high and 0V for low whereas signals A and B are at a level of 4V.

How can this be done? Using a Mosfet with C as gate and A and B as Drain or source, respectively will not work as C would have a lower voltage than the source. Therefore, the difference G - S would always be negative.


texts: STM32 Standard Peripheral Library (SPL) - Modify SPI Configuration

texts:
I am using the STM32 SPL library with an STM32F103C8 microcontroller. As part of the project, I am using the SPI1 peripheral to interface with an SD card.

Initially the SPI speed must be kept under 400 kHz for the SD card. My SPI1 initialization code is

SPI_InitTypeDef spi;

//ENABLE THE CLOCK TO SPI1 PERIPHERAL
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);

//SET SPI SPEED TO LOW SPEED MODE (~282KHZ)
spi.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;
spi.SPI_CPHA = SPI_CPHA_1Edge;
spi.SPI_CPOL = SPI_CPOL_Low;
spi.SPI_DataSize = SPI_DataSize_8b;
spi.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
spi.SPI_FirstBit = SPI_FirstBit_MSB;
spi.SPI_Mode = SPI_Mode_Master;
spi.SPI_NSS = SPI_NSS_Soft;

SPI_Init(SPI1, &spi);
SPI_Cmd(SPI1, ENABLE);

Of course, once the initial initialization of the SD card is complete, I would like to speed up the SPI1 peripheral.

I could not find any function in the SPL that would return a structure of the type SPI_InitTypeDef containing the currently configured settings of an SPI peripheral.

Does that mean I have to create a new such structure (and repeat all the configuration values even if I only wish to change the speed and keep the rest the same as already configured) and then call SPI_Init() with this new structure?


texts:
I bought a cheap computer Sub to repurpose it as a selfmade gaming vest. The circuit has 2 amplifiers on it, one for the normal unfiltered sound that goes to the 2 speakers, and then the output of this one is filtered and sent to a second amplifier for the subwoofer.
The filtering is not great... I tried with a wave generator and got clear, loud sound up to 11.000 hz... I would like to add a low pass filter that has a cutoff frequency of 200Hz on the input of the second amplifier.
I found a 1uF capacitor at home, and after googeling around i somehow came up that with that capacitor I would need a resistor of 820Ohm to have a cutoff frequency of roughly 195 Hz.

Is that correct?
Wouldn't that resistor in series lower drastically the input volume to the amplifier?


texts:
I found this circuit for conditioning the signal for the PedalShield Uno(Guitar Effect Pedal made using Arduino). I am trying to make a similar project and I copied the circuit but the Op-Amp that I have bought (only one available) is AD8051. The one on the circuit is supposed to be TL972.

I have no understanding of these matters and I would very much appreciate if you can point out the different parts of this circuit and its functionalities. I only know the first part before the op-amp are low-pass filters. I would like to understand this circuit so I can make my own for the AD8051 or if I can avail the TL061.


texts: Can a 2k thermistor be converted to a 10k output?

texts:
I have a 2k ohm sensor that fits properly but I can not find a proper 10k that fits a M14 hole for the water temperature on my car.
The gauge I am using only reads the NTC 10k thermistor so I was wondering if it was possible to convert the resistance. Bit new to the thermistor world.


texts:
Is it ok to increase the time between BLE advertisements to longer than 10.24 seconds? I know 10.24 s is the longest time I can set for the advertisements to automatically repeat, but I can also manually turn advertising on and off.
If I set a timer for 1 minute to enable advertising, send out the advertisement packet, and then disable advertising for another minute, is this violating any BLE rules?  Our system is constantly scanning for our beacons so we won't miss any advertisements, I'm just trying to save some power by not having to transmit so often.


texts: Band-pass op-amp structure with parallel diodes in feedback?

texts:
It's been a while since I've done analog circuit theory, and I'm trying to interpret the 2nd gain stage sub-circuit in this schematic for a guitar pedal:

I'm not sure if I'm approaching the circuit correctly, but I noted that if the magnitude of Vout is less than the forward-bias of the diode(s), this becomes a 2nd-order bandpass filter structure, where the high cutoff frequency is controlled by the gain potentiometer.
Does this mean that this is essentially just a bandpass filter that also clips the output?
This article kind of explains the sub-circuit from a different approach, and I can't tell if their analysis contradicts mine or not:

[...] there's a cap in series with the Rin resistor. This forms a high-pass filter with a corner frequency of ~72Hz, so all of your bass will pass through. Then there's a set of LEDs used for soft clipping and a 47pF cap to smooth out some of the treble content. Overall, this looks a lot like the tube screamer clipping section. The major difference is that it uses LEDs (a common TS mod) and the corner frequency on a Tube Screamer is much higher, cutting out a lot of bass (~720Hz).


texts: Is there any function for multiplying two voltage waveforms in LTspice?

texts: Does LTspice have such functionality? I want to multiply two voltage waveforms with each other by an ideal multiplier. How to construct such a multiplier? Is that even possible?


texts: Why does my multimeter show a higher current with lower sensitivity when measuring AC current?

texts:
For measuring AC current my multimeter has the options:

I just wanted to measure an AC current which I expect to be around 1A. Here are the two measurements I did:

What I always thought was that the 4 sensitivity measuring options for AC currents are meant up to 200μA, 2mA, 20A and 200A ordered increasingly on the multimeter. But why is it showing 9.5 when I select "200" on the meter instead of 1 or something? Before when it was set to 20A it showed me the 0.95A as expected.
What is the explanation for that?


texts:
I designed an voltage divider and I have a problem (misunderstanding) when turning ON one of the transistors

For Q2, I realise that the GND is in the others drain pin transistors (Q4, Q5).

Other problem is the input voltage can be up to 48V, and i want to measure it with an microcontroller, so when all the transistors are off the voltage at the ADC pin will be 48V.


texts: Microcontroller goes endless loop while power up

texts:
I am using atmega328pb controller and Arduino Framework with mini-core. The problem is that the microcontroller goes into a never-ending loop while power up. I found this while debugging.
Actually, I am using while(1) loops in the program, and temporarily I have solved this problem by using the watchdog timer. Please check the below code for more details.
Can anyone let me know the reason for this problem?
 bool Fault_ckeck()
{
  if (millis() - FAULT_CNT > FAULT_TMG) return 1; else return 0;
}

bool WCO_Fault_ckeck()
{
  if (millis() - WCO_FAULT_CNT > FAULT_TMG) return 1; else return 0;
}

bool WCFR_Fault_ckeck()
{
  if (millis() - WCFR_FAULT_CNT > FAULT_TMG) return 1; else return 0;
}

bool WCUP_Fault_ckeck()
{
  if (millis() - WCUP_FAULT_CNT > FAULT_TMG) return 1; else return 0;
}

void WCUP_EMR_STP()
{
    DWGUP.hardStop();
    DWCFR.hardStop();
    DWCO.hardStop();
    while (1) {
      if (STARTUP_FLAG == START_TOTAL) wdt_reset();
      if (millis() - ER_SIG_CNT > WCUP_EMR_STP_TMG) {
        digitalWrite(EMR_STP, !digitalRead(EMR_STP));
        ER_SIG_CNT = millis();
      }
    }
}

void WCFR_EMR_STP()
{
    DWCFR.hardStop();
    DWGUP.hardStop();
    DWCO.hardStop();
    while (1) {
      if (STARTUP_FLAG == START_TOTAL) wdt_reset();
      if (millis() - ER_SIG_CNT > WCFR_EMR_STP_TMG) {
        digitalWrite(EMR_STP, !digitalRead(EMR_STP));
        ER_SIG_CNT = millis();
      }
    }
}

void WCO_EMR_STP()
{
    DWCO.hardStop();
    DWGUP.hardStop();
    DWCFR.hardStop();
    while (1) {
      if (STARTUP_FLAG == START_TOTAL) wdt_reset();
      if (millis() - ER_SIG_CNT > WCO_EMR_STP_TMG) {
        digitalWrite(EMR_STP, !digitalRead(EMR_STP));
        ER_SIG_CNT = millis();
      }
    }
}

void STARTUP_WCUP_EMR_STP()
{
    DWGUP.hardStop();
    DWCFR.hardStop();
    DWCO.hardStop();
    while (1) {
      if (millis() - ER_SIG_CNT > WCUP_EMR_STP_TMG) {
        digitalWrite(EMR_STP, !digitalRead(EMR_STP));
        ER_SIG_CNT = millis();
      }
    }
}

void STARTUP_WCFR_EMR_STP()
{
    DWCFR.hardStop();
    DWGUP.hardStop();
    DWCO.hardStop();
    while (1) {
      if (millis() - ER_SIG_CNT > WCFR_EMR_STP_TMG) {
        digitalWrite(EMR_STP, !digitalRead(EMR_STP));
        ER_SIG_CNT = millis();
      }
    }
}

void STARTUP_WCO_EMR_STP()
{
    DWCO.hardStop();
    DWGUP.hardStop();
    DWCFR.hardStop();
    while (1) {
      if (millis() - ER_SIG_CNT > WCO_EMR_STP_TMG) {
        digitalWrite(EMR_STP, !digitalRead(EMR_STP));
        ER_SIG_CNT = millis();
      }
    }
}


texts:
I would like to Interface a BLE to a MSP432 microcontroller in serial. The BLE has a inbulit Atmel controller. I have a firmware for BLE in keil. Intially I have flashed the firmware to BLE directly from a debugger and worked on the BLE. Now I should have a MSP432 in btween debugger and BLE.

I should flash the BLE via MSP432 in serial. I am planning to connect the hardware as below image. Is this way work out?.
My another important question is I have to write the firmware for MSP432 and then combne the BLE code in to the MSP432 code?.

If so How can I send the perticuler BLE portion of code to the BLE?.

If I dont connect the seial pins of debugger to MSP432 how can I see the serial data on terminal in PC?.


texts:
I am quite new to this subject. I want to design a frequency mixer to mix a carrier frequency of 100 MHz with a 20 kHz signal. I found the attached circuit. It seems quite a simple circuit to multiply both circuits obtained. However, I don't know and couldn't find how the resistor values could be found. Could someone please show me how to calculate their values please.
Moreover, what should the ratio of the transformer be please. Also, if there exists a simpler option on how to design a frequency mixer, it still works fine for me since I am willing to use any circuit.
Thanks for your help.


texts: How do diodes work in an AM band application?

texts:
I have been trying to build an AM radio for a while now and with continued failure, I am trying different avenues.

I understand that Germanium diodes have a forward drop of about 0.3V; to be sure, I put the diode in series with a resistor to measure the diodes forward drop.

What I don't understand is how so many "How to build an AM Radio" articles take the signal directly from the antenna and pass it through the diode. I have used a large monopole antenna (about 20 feet) connected to a tuner circuit (200-1800uH inductor and 10-360 pF cap) and I do not get anywhere near 0.3V.

simulate this circuit – Schematic created using CircuitLab

So, I would like to know, how do diodes work in an AM Radio? There must be something that I am not understanding or doing properly because I have not yet been able to receive and demodulate a signal in my attempts.


texts:
I am making a robot with two coin batteries rated at 3V and using ATMega164 microcontroller. I am trying to run the motors in both directions for which I am using an h-bridge. I need it to be surface mount so I ordered 'LA6585FA-BH'. I connected its IN+ and IN- inputs to OCR0A and OCR0B pins on the micro, the OUT terminals connected to the motor and CT connected to ground.

While I was testing this h-bridge I noticed that the motor goes in one direction but in the other direction it wouldn't. So when OCR0A = 0 and OCR0B = 255 the motor works but when the values are the other way around it wouldn't work. Also, I noticed that when the power (Vcc pin) is cut while everything else is connected, the motor still vibrates but very little. Shouldn't the motor be completely switched off when Vcc is unplugged?

Do these h-bridges usually work like this or is it something that I'm doing wrong?


texts: What makes automotive alternators so inneficient relative to other applications?

texts:
Automotive and some marine alternators typically have an efficiency curve with a peak of 60%.

Image from http://www.intechopen.com
Whereas alternators to other types of applications reach 96% of efficiency (excited rotor type).
What are the factors that makes then so inefficient compared to other applications?
Is pole-number, air-gap? Could the efficiency be improved with some modifications for
stationary use or the unique way is maintain the speed at the peak of efficiency?
UPDATE
@olinlathrop suggested somethings, among that the environment the alternator works
(temperature, vibrations, dust) means their robustness can be a trade off to the
efficiency.
I agree in some points, although there's no objective answer, good sealed bearings
would not decrease the efficiency that much, so I think temperature can be
one of the factors as they are small and works near a combustion motor, even trough
have their own forced ventilation.
Anyway where is an alternator with stated 80% efficiency at 450A 24A! That's ~10Kw.
http://www.emp-corp.com/media/MarketingMaterial/Power450/SpecificationSheets/Power450.pdf
The difference is that this alternator uses magnetics instead of electro-magnets in the rotor. Anyway, the ~95% efficiency alternator product sheet I read is a excited rotor one.


texts: How to use phasor algebra to solve for capacitive reactance?

texts:
I have an RLC series circuit.

Voltage supplied by volatage source as a function of time: \$V(t) = 230 \sin(\omega t+\pi/4)A\$.

Current in circuit as a function of time: \$I(t)=10\sin(\omega t - \pi/6)V\$

The value of the resistance is \$5\Omega\$ and value of inductive reactance is \$8j\Omega\$. I need to find the value of capacitive reactance \$X_{C}\$.

I tried to solve like this (using phasors i.e. polar representation):

$$230/\sqrt{2}e^{j\pi/4} = (5 + 8j + X_{C})(10/\sqrt{2}e^{-j\pi/6})$$
$$\implies 23e^{j(\pi/4+\pi/6)}-5-8j =X_{C}\implies X_{C}=(0.95+14.21j)$$

[Ohm's Law]

However, while writing this, I realized that the left hand side's real part is not equal to the right hand side's real part. When I solve for \$X_{C}\$ I get \$(0.95+14.21j)\Omega\$ which is impossible since \$X_{c}\$ (capacitive) must be imaginary with a phase factor of \$-j\$.

I'm confused about how to use phasor algebra to solve this problem. Any help will be appreciated.


texts: how to Calculate Equilibrium point of equations

texts:
I was reading an article about finite state machine and boost converter.
I don't know how to calculate the equilibrium point
$$v^* $$
for convenience the equation of v is
$$ v = \frac{v_in}{1-d_n} $$
Can anybody paste link about how the calculation made here.

Thanks


texts:
I am using a 5V 40 mA (max current) output on an Arduino to turn on (5V) or off (0V) as laser driver. The laser driver requires a max voltage of 2V to turn it on and flips at 0.8V. How can I lower the 5V to 2V for the driver?

Thanks in advance!


texts:
total novice here so forgive me if I sound daft.

I’m currently building a circuit that is using a small DC motor in reverse to charge a battery. One like the Anker Powercore type. I currently have 2  capacitors in the circuit to smooth out the current but am wondering if I can use a diode to ensure that the battery doesn’t just spin the motor when not in use?

Anyone have any insight?


texts:
I understand that:

For purely DC current with fixed DC voltage, the DC & RMS current value will be the same, means that the total power RMS & DC will be the same using Pdc = Idc x Vdc
For pulsed current with fixed DC voltage (example flyback switching), RMS current value will be greater than DC current value, however the RMS will be not count in for power consumption, therefore the power consumption is still based on Pdc = Idc x Vdc

Based on that, meaning that in every calculation, I need to use DC current for power calculation, not RMS value.

By using simulation, I managed to get RMS & average value at my flyback secondary side. Both value are correct based on my calculation. Refer image below:

Questions:

How to convert RMS current to average current? I noticed that most of power supply calculation will produce RMS current (example secondary RMS current, not secondary average current). Most of the time, I will use Pdc/Vout to get the average current, but how can I estimate the average current from the RMS current?
How can I measure this average current in actual condition? I noticed that most of my equipment (example oscilloscope, multi-meter) is based on RMS value & not average value.
What is the actual purpose of this RMS current value? When do we use this RMS value in real situation?

Thanks


texts: Eagle - non solder mask defined (NSMD) pads

texts: I am designing a PCB layout in Eagle and in the datasheet of my modul it is said that "Non solder mask defined (NSMD) type is recommended for the solder pads on the PCB". Does it mean that there will be no solder on pads? By default pads are enabled for tStop and tCream in Eagle. Should they be ON or OFF in this case? How can arrange this situation in Eagle?


texts: Optocoupler/isolater circuit for 24VDC sense that transfers switch status to 3.3VDC microcontroller

texts:
hope everyone is having a good couple weeks before Christmas, I was given this question for an assignment

How would you use an opto-isolator to sense a switch status in a 24VDC machine control circuit and transfer this status to a 3.3VDC/5VDC microcontroller input (something like an arduino uno). Explain how your circuit works. (this was posed to me as a general question, so i would assume the 24VDC motor circuit would have a transistor and diode for protection). NOTE***: I've only sim'd the 24VDC source in this case

So what I have done so far below is use a 4n25 optocoupler, to try and send a low signal to the controller when the 24VDC switch status is ON and a high state when the switch status is OFF. Pic 1 would be ON and Pic 2 below Pic 1 would be OFF. Any sort of clarification regarding the following would be much appreciated :)

When the switch is closed, why is the voltage at PR1 4.5V? is there like an extra voltage drop(s) due to the IRLED inside the coupler and the resistor?
Would an NPN BJT connected via separate 5VDC be a better idea to supply the IRLED rather than a voltage divider? If so, where would I connect it?
This last a bit vague I apologize, but practically speaking, would this circuit even work? All I have right now is the sim and a lack of parts to realize it