texts: Convert continuous signal of HC-SR501 PIR sensor to a single pulse

texts:
HC-SR501 PIR sensor sends a continuous signal of 0-3.3V for the period of 4-8 seconds (depending upon the delay set).
Is there a way/IC I can convert this signal to a single pulse of 1 sec, preferably without using a micro-controller?


texts: Five Plate Capacitor - How to calculate?

texts:
I'm taking an electrical engineering course as part of my Bachelor's degree, and sadly our tutorials don't seem very well laid out. We've been given the following capacitor and asked to calculate capacitance and charge.

I have the formulas but can't figure out from the image if the capacitors are in series or parallel. How can I approach the problem?


texts:
If a battery looks like this:  And a battery series looks like this:

How is it possible for electrons to go from the positive side of one battery to the negative side of another battery and then keep on going; without stopping?


texts: Improving PWM by using comparison to LFSR instead of counter

texts:
PWM is a very powerful technique to simulate an analog output from a microcontroller, programmable logic or any other digital environment. This can be used to drive LEDs, motors and speakers, etc... without the need of an external DAC component (in some cases a low-pass filter is necessary).

A PWM is typically made by using a counter and a comparator. The counter constantly counts and rolls up, and when it is above a threshold value (the desired % of output voltage), then a '1' logic is send, when below a '0' logic is send.

The main problem of PWM is that there is a tradeoff between precision and frequency: If one more bit is needed for precision, it means that the counter will take twice as long before it rolls again, and as such the parasite frequencies that will have to be filtered off are lower in the spectrum, thus closer to the signal and harder to filter.

For these reasons, PWM is inapplicable for signals that should either

Have high analogue frequencies
Needs too many bits in the DAC

My idea is simple, instead of using a N bit counter, I use a random number generator, made by taking the high (or low ?) N bits of a M bit LFSR (for example, use the lowest 8 bits of a 16 bit LFSR). That way, instead of outputting a square wave with a variable pulse width, we output a steam of random pulses.

The probability that a pulse is '1' is equal to the ratio between the desired output voltage, and the maximum output voltage. As such, the result is exactly the same as PWM, exept that the parasite frequencies are now random, and such are much easier to filter. It is now possible to add as many bits as necessary for the ADC, and this won't cause any problems.

For example, it becomes possible and actually very simple to have 16-bit Audio output with a 1MHz clock. With traditional PWM this would never has been possible: Only a 5-bit audio signal would have been possible without either a hearable audio fuzz.

Will this work? Since this idea is so simple and improves the PWM technique so much, why is it not mentioned in anywhere?


texts: How to read the voltage of a bunch of batteries in parallel?

texts:
simulate this circuit – Schematic created using CircuitLab

What are the equivalent/thevenin voltage?
It is very confusing, even with just one battery, like this:

simulate this circuit

Are the voltage 0? Since the resistor exhaust all the energy that the battery gives it.


texts:
Concerning the HIP4082 IC from intersil. I was asking about the input to the IC. Pins (ALI,BLI), can I use a very low frequency input on these pins for example to control a stepper motor, so the frequency won't be stable sometimes up to 1 KHZ and other times as low as 1 HZ or even slower.
The problem is how will the bootstrap capacitor be charged ?


texts: What does mean I2C Firmware controlled Master operation, Slave is IDLE

texts:
I am trying to learn I2C bus. For learning purpose, I am using PIC 16F72. In PIC 16F72 microchip datasheet, I see if I want to use this microchip as a master it has a mode which is

  I2C Firmware controlled Master operation, Slave is IDLE
  [p. 48 in the PIC 16F72 datasheet]

I didn't understand what does mean this.


texts: Simulating a variable mutual inductance model

texts:
Can we simulate a time varying mutual inductance in Matlab Simulink (or any other simulation tool).

Matlab Simulink has a variable inductor, but I could not find not mutual inductor.


texts: Does AMP AC/DC adapter going through a step down increase in amps per voltages (ECIG)

texts:
The latest project I'm working on is making adapter to basically use the mains for an ecig rather than usb or an battery. For anyone whos familiar with ECIGS they basically use around 3.7-6volts. It's my understanding that the resistance in the coil a ecig determines the required amps, for example:

3.7 volts with coil resistance of 3 ohm you will use around 1.233 amps. This is 4.56 watts.
3.7 volts with coil resistance of 4.5 ohm you will use around 1.233 amps. This is 4.56 watts.
6.0 volts with coil resistance of 3 ohm you will use around 2 amps. This is 12 watts.
6.0 volts with coil resistance of 4.5 ohm you will use around 1.333 amps. This is 8 watts.

The step down I'm using is rated as so:

Input voltage range:4-40V
Adjustable output voltage range:1.25-37V
Operating current:2A

The ac/dc adapter I'm using is rated:

INPUT: 220-240v AC 50Hz 350mA
OUTPUT: 12v DC 750mA

Question: If I step down an input of 12v with 750mA to say 6v does the 750mA max remain the same or does this change because the voltage is lower? if so how much would it increase by and what is the forumula when down stepping.

... Apologies if this question has been asked time and time again, I'm sure it has but searching through all the step down questions I couldn't find an appropriate answer or question, only that of increasing voltage.


texts: What is the maximum length of serial cable I can use, to connection work properly? Is length of serial cable in connection with baud rate? I am using about 5 meter cable at speed 38400 bauds and RS232 communication, is it too long?


texts: Bi-polar input (AC) to be used in op-amp

texts: I am planning to amplify AC signal (without sacrificing dynamic range) using MCP602(Microchip), but the datasheet shows input voltage is from 2.7V to 6.0V. My question is can I use negative supply in the MCP602, instead of ground. Do dual supply op-amps are different from signal supply op-ams, or can we use both interchangeably.


texts: Mapping a voltage range to whole ADC range using opamps

texts:
I want to use a micro for measuring temperature using PT-1000 sensor for range -40C to 150C. I have come up with these draft information, I appreciate it if a pro person can confirm my thoughts are OK before I pay a lot for parts and PCB and fail miserably.

The ADC of micro is 3.3V and 12bits. so it means 0V willl be 0 and 3.3V will be 4095 (in an ideal world?)

I have checked the PT1000 LUT, it seems that at -40C it has 842.7 Ohms and at +150C it has 1573.3 Ohms.

so I need to adjust this range for my ADC input. e.g. at -40C the ADC should show 0 and at 150C it should show 4095.

Here is the initial voltage divider, I chose R25 to be 10k to limit the current and possibly noise as well? so at -40C and +150C the voltage going to the input of first opamp will be:
$${V_{-40} = \frac{3.3\times842.7}{10k+842.7}= 256_{mV}}$$
$${V_{+150} = \frac{3.3\times1573.3}{10k+1573.3}= 449_{mV}}$$

So I need to map 256mV to 449 mV to approximately 0V to 3.3V, hence the amplification stages here:

For mapping -40C to 0V I have (dont mind the values in the picture, they are not up to date) R26 = 33k and R27 = 2.7k, which yields:
$${V_{out} = \frac{3.3\times2.7k}{33k+2.7k}= 249_{mV}}$$
which is 6.4mV less than 256mV (I choosed the resistor based on E12 range)

And finally I need a gain of 7.34 to map 449mV to 3.3V:
R30(feedback) = 68k, R28 = 10k Therefor gain = 68k/10k = 6.8x

So again, before I pay lots of money for PCB and components, do you think I will achive what I need?


texts: Sensorless driving of 3 phase BLDC motor for gimbal applications?

texts:
I have started to work on a project of mines, which consists in implementing the stabilization of a single axis gimbal using a generic microcontroller (STM32 or
Arduino Uno).

The gimbal axis is driven by a sensorless three phase brushless DC (BLDC) motor, while on it's shaft there is a generic payload provided with an IMU board (3 axes gyros + 3 axes accelometers), which can give feedback to the microcontroller about the angular rates and accelerations of the motor.

The microcontroller is feeding an inverter bridge (L6234) in order to drive the BLDC motor.

I have googled a bit about this topic and there are so many solutions out there for high speed applications, but not that much for low ones.

Moreover, the thing I really do not understand is about the control of the BLDC motor, so my questions are:

Can I use a sensorless control of the motor, by sensing the back EMF
even if the motor is spinning very low?
How can I energize properly the phases of the BLDC motor, from standstill, if it is sensorless?
Can I use the IMU for finding out how to spin the BLDC motor properly without counter rotations (meaning that I know when to commutate)?
How can I hold the motor standstill when reaching the setpoint?
Should I implemebt a speed controller or a torque (current) one for such an application (sensorless driving of BLDC motors at low speeds)?

Could you give me any help, please?


texts: Automatic distinction between PC-USB and Wall Adapter-USB

texts: I want to ask if it's possible and an advice on how to make an automatic distinction between an PC-USB port and Wall-USB adapter. I've a battery charger IC (for example http://www.mouser.com/ds/2/405/bq24074-556796.pdf) where I can set max. IN current. I have no problems to set it to 500mA, but I'll always charge the battery at 500mA in PC and Wall-Adapter. But I want to charge the battery at 1-1.5A when I connect it to Wall-Adapter and when I connect it to a PC I don't want to fry PC usb port and charge battery at 500mA. Something like in a smartphone. I thought about sending some data via usb to know if it's an PC or Adapter but I need something more safety and always working.


texts: Does an ATX power supply have any isolated outputs?

texts:
I am working on an application that requires isolated power inputs.

Wondering if the standard ATX PSU has any isolated outputs?

Why are we having  multiple ground pins on the Connector?


texts: Using Atmega 328P barebone with non-standard crystal oscillator

texts:
The standard barebone setup would be with a 16Mhz crystal oscillator and 2 caps:

https://www.arduino.cc/en/Tutorial/ArduinoToBreadboard

However unfortunately I only have the following crystals available:

12.000 Mhz

33.8688 Mhz

24 Mhz

27 Mhz

Is it possible to use the chip with these and how would it effect the run? I have some delays in the code which should be respected but no need for accurate timing, if it's shifting a bit (eg there is a delay for 5 minutes and it's 4.9 instead that's ok).


texts:
I have that circuit and I need the equation of Vo, I've been told that I can solve it by the Kirchhoff method but I'm not sure.

Is there a way that the expression looks like Vo=K(V2-V1) ?


texts:
Implement a current source, with cascode topology, using Diodes Inc's 2N7002K MOSFET, satisfying the following requirements:

Use a voltage source of 5.5 Volts
\$ i_{out} = 6 ~ \mu A\$
\$ V_{out_{min}} < 2.5 V \$
\$ R_{out} > 0.7~G\Omega \$

Asume that the n-MOSFET has a \$\lambda= 104~\mu V^{-1}\$

My attempt:

simulate this circuit – Schematic created using CircuitLab

Here you can see the simulation (using an arbitrary \$150k\Omega\$ load), and the output current works fine. My concern is with the output impedance.

My question is how to compute the output impedance of this n-MOSFET current source?

I'm not sure if in this case I can use the (known) small-signal output impedance formula of a cascode configuration wich, according to Sedra-Smith, is \$ r_{out} \approx g_{m} r_{o_1}r_{o_2}\$, where \$r_{o_1}=r_{o_2}=r_o=\frac{1}{\lambda I_D} = \frac{1}{106\mu V^{-1}\times 6\mu A} = 1.6~G\Omega \$

My guess is that I can not use this formula, because my current source is a DC source (\$ \neq \$small signal) while this formula was deduced from the small-signal model.


texts: What do moving rails (voltage shifting on the rails) do to an opamp?

texts:
Since I've spent a good portion of my career trying to get opamp's rails as steady as possible at their intended voltage, I haven't really spent any time thinking about what would happen if the rails are moving away from a fixed value. Since I have only briefly studied the internal workings of op amps, I'm not so sure I could come up with a definite answer.

So, what does happen to the signal if the rails are moving? (lets just say there moving slowly, like less than 5Hz, maybe a 1V shift from time to time) Is it more than just clipping at different levels?


texts: Calculating the discharge of Ultra Capacitors

texts:
Say I have two 500F ultra capacitors, connected in parallel, charged at 15V.

These are the capacitors BMOD0500 P016 B01.

Then say I connect the capacitors (via an inverter) to a 230V light bulb that draws a constant 280W of power (the inverter disconnects at 10V).

What equation would I use to calculate the amount of time that the circuit would remain active?

Please ignore the efficiency of the inverter, I'll take that into account later.


texts: Install grounding cable with eyelet to outlet, no center screw

texts:
I've found an ESD mat that comes with a grounding cable with an eyelet that's supposed to be screwed into the center (grounded) screw of an electrical outlet. But in my home, the outlets do not have one center screw; they have two screws, a top one and a bottom one. Would either of these screws be grounded? If not, how would I connect the grounding cable?
Edit: The outlets are three prong. I live in Canada.


texts:
I am simulating a DC to AC converter on LTSpice and I used if statements to make the circuit work. These if statements are located near the top of the image below, where the "lonely" voltage sources are. How do I implement these if statements on the breadboard? Someone told me to use a driver circuits and I looked for one on google. However, I am not sure how to construct/simulate a driver ciruit using basic circuit elements in LTSpice.
enter image description here


texts:
Disclaimer : this question may be more 'physics' than electric engineering

So suppose you have a circuit with a battery and some other elements, the elements, the battery continuously provides energy to the circuit lets say 'E' by the kirchoff voltage law all this energy should be used up as you loop the circuit. Now my question is how would you find the minimum amount of energy which you would need to run a circuit , or how do you find the current/voltage rating given on the back of electirc products?


texts: space constrained, cost constrained; super capacitor UPS decision paralysis

texts:
I am currently in the process of evaluation of options regarding Super capacitor UPS designs.

The requirements are simple, find the most effective solution to keep alive 5V supply line for ~20 seconds.

The initial expected current is around 2.5A, decreasing after around 10s to 1A.

I've looked on existing designs, especially the wide range of Raspberry UPS products and I find them all over complicated and unnecessarily expensive. (Maybe I am the one who's wrong and oversimplified solution just can't be designed)

State your opinion which one of these solutions seems to be the most viable to you, alternatively, state what issues might prevent the UPS designs from working correctly.

Here are solutions that I've shortlisted so far:

Using hyper integrated solution from Advanced Linear: LTC4041 (charging, balancing, switchover, overvoltage...)

Although this solution is probably the most technically correct, I find the price outrageous and I would have to sacrifice other functionalities to fit this design within budget.

Approximate BOM: ~5$ (not counting the supercap)

Using Two Supercaps in series, charging via efuse, with pass-trough step up converter

The efuse function is just to slowly ramp up the voltage so that the super cap can charge correctly and not cause inrush current spike. Additionally, the load is turned on after the charging process is over. The ultra slow rise might mess up the power sequencing thats happening down the line.
The problem is that the 1uH inductor might cause interferences with the load and cause power loss during normal operation.

Approximate BOM: ~0.8$ (not counting the supercap)

Option with stacked super capacitors

Using single supercap charged via abused step down (using internal short circuit protection as constant current source, Power good as "done charging" signal) with pass-trough step up converter and ideal diode.

Honestly, I am not quite sure if my barbaric approach to constant current dc-dc will work. The controller could just latch off the entire circuit, or it might be harmful in the long term. Someone more experienced, state your opinion.

To explain what the "ST" of ideal diode does: basically, if it is conducting, it shuts down the buck converter to prevent the current form looping back to the supercap.

Approximate BOM: ~0.5$ (not counting the supercap)

Datasheets:

Ideal diode: http://www.ti.com/lit/ds/symlink/lm66100.pdf?HQS=TI-null-null-mousermode-df-pf-null-wwe&DCM=yes&distId=26

step down: https://www.ti.com/lit/ds/symlink/tlv62568a.pdf?ts=1590506250082

step up: https://www.ti.com/lit/ds/symlink/tps61022.pdf?ts=1590506435590


texts: What are these transistors doing and how are they working in this VU Meter?

texts:
I was thinking of making KITT's voice box from Knight Rider, which is essentially a VU meter. I did some researching and found an appropriate IC, LM3916,

http://www.mouser.com/ds/2/405/lm3915-443929.pdf

and some LED Bar Graphs. I actually ended up finding what seems to be an old schematic, in this link (it uses the LM3915). There's a group of PNP BJT's in it.
Schematic

It's a bit hard to follow, I made my own so I can follow the wiring a bit better, if you would like to look it's below(It's missing the resistors in the LED bar graphs, it should be 180ohms like the original schematic)

.
(My design uses 625ohms due to a mistake I made reading the datasheet. They should be 1k)

The author writes the BJT's are for to light multiple LED's (since each LED output on the chip is suppose to only supply 1 LED). So essentially he uses the IC to select between the transistors which will turn on the LED's.

I'm confused on how they are doing this. It's a PNP BJT. According to the LM3915 datasheet, the current this IC will be outputting at the LED outputs is 12.5mA, since 12.5V/1k. Then 12.5mA going through the 1k resistors at the outputs give 12.5V again.

So first, Vb = 12.5V. Ve = 12V from the supply. Veb should be .7V, but this gives -.5V. Vb would have to be 11.8V to have a Veb of .7V

Second it should be Ie = Ib+Ic, meaning the base current should be flowing out, but the current is coming in from the IC.

I tried making a simple overview of 1 LED, not sure if it's correct

Third, let's say there was just 12V going to the LED's. The design the person has uses 180ohms. (12-Vf)/180 = If. Red LED's I read generally have around 2V Vf, so 12-2/180 is approximately 55mA. That seems extremely high, and it also produces really high wattage.

Thanks!

LED Bar Graph Data Sheet: https://www.sparkfun.com/datasheets/Components/LED/YSLB-102510R3-10.pdf


texts:
I'm currently learning about power supply circuits (mostly because I want to make my own to power an LED strip). Everywhere I search I find the same basic principle:

Transformer -> Rectifier -> Filter -> Regulator -> Load

So my first question is: do these building blocks ever change? Are there some appliances where these are not enough? To me it just seems rather too simple.

Next there are some circuits that follow the plan above, like this one (taken from https://www.build-electronic-circuits.com/power-supply-circuit/):

So if I'm following the plan above, can this be made more advanced? Or is it enough for most applications?


texts:
GPIO pin from MKR1000 is rated 3.3v 7mA
I need a relay which has the sale coil rating.
So far I have not been able to find one.
What I have seen is that as the coil voltage goes down, the coil current goes up. Normally 3v coil volt relays operate at 50mA.
Can you suggest a relay which will work in my situation?


texts:
[icarus verilog]

Is there some flag / pragma which can help me in detecting bogus variable names in a module definition?

Consider the following code fragment ...

module binary_decoder_2to4
(
    input wire enable,
    input wire[1:0] a,
    output wire[3:0] y
);

assign y[0] =  en & ~a[1] & ~a[0];
assign y[1] =  en & ~a[1] &  a[0];
assign y[2] =  en &  a[1] & ~a[0];
assign y[3] =  en &  a[1] &  a[0];

endmodule

As you can see I renamed port en to enable but I forgot to update the module body. Coming from a programming background I would expect the compiler (iverilog) to at least sound a warning. Instead the compiler happily generates a simulation file with the value of en set to z.


texts:
I've been working with an ADC which requires AVdd-AVss for the analogue part and Vcc-GND for the digital part. The power was supplied through regulators to get a clean voltage.

In this schematic AVss was taken out from JP4 and GND was taken from JP3.

Aren't both AVss and GND the same here? If yes, why is it take from two places?


texts: Can I use per unit method for true, reactive, and apparent Power

texts:
I would like to show apparent power (S) in Cartesian coordinate system with a circle of radius 1, where x axis represents reactive power (Q), and y axis represents true power (P). There's the formula:

P^2+Q^2=S^2

Can I use these formulas to transform it in per unit system:

P[p.u.] = P / S
Q[p.u.] = Q / S
S[p.u.] = S / S = 1


texts:
I'm thinking about making a reverse polarity protection for a buck converter AOZ1284, and I've found this article design-guide-pmos-mosfet-for-reverse-voltage-polarity-protection
I didn't find the spice model for AOZ1284 to simulate the full circuit.
My question : Can I use this circuit with the buck converter (I am working with 12V as input)
AOZ1284 DataSheet


texts: I am having difficulties finding the equivalent resistance between points A and B. While a solution is appreciated, I'm rather looking for an explanation/redrawing and understanding of the circuit. Thank you.


texts: Choosing the right opamp for biasing a square wave

texts:
I am trying to bias a 1MHz, Vpp = 1V, bipolar square wave signal coming from an opamp.
I want to bias it by 1V, the 1V bias (Vcm) is available at an ADC's output port.
I am thinking about using this circuit with a rail to rail opamp:

I know I will get an inverted signal, but I can simply invert it again.

How do I choose the correct capacitor value?
What voltage do I need to apply to the rails?
Do I need a resistor between the ADC's Vcm output and the opamp's Vcm input?
I will need an opamp with a gain bandwidth product of 10 times the square wave frequency, right?


texts:
If I'm correct, AN in below picture is an electromagnet.
When the switch S is pushed, the electromagnet AN connects L1 to T1 and L2 to T2.
When the switch S is released, the electromagnet AN disconnects the same.

If we want the electromagnet to remain active even after releasing the switch S, we modify the circuit as below.

I think this works because

When the switch S is released, the electromagnet AN doesn't go off immediately.
The phase passes through T2->L2 immediately, powering the electromagnet AN.

Why are we assuming this? This will not work if the electromagnet goes off before the phase passes through T2->L2. What am I missing here?

My ideas.

When the switch S is pressed, the voltage across L2-T2 is 0. So no current flows through L2-T2. So how can huge curent immediately begin to flow through L2-T2 when we release the switch S?


texts: Designing Under/Over Voltage LiPo protection circuit

texts:
I am currently trying to design a protection circuit for a project of mine that uses a single cell 3.7v lithium ion battery. I found this image online which uses 2 TL431s:

However, I am really not that good at EE, so I am clueless as to what the unlabeled resister values would have to be in order for this circuit to function properly. I realize that there are protection circuit ICs, but I want to build the actual circuit myself. Does anyone have any insight as to how this circuit works and what the resistor values would need to be?


texts:
555 timer oscillator circuit
How can i get 50% duty cycles?


texts: I find it difficult to see the elecrtical specs of ATX PSU. You can, for instance, have this cheap block or another one but their homepages just say that PSUs are ATX-2.2/2.31 compliant and I see no min/max currents they give me on their rails. What does it mean? Probably I have a duplicate of current distribution but I want to put the question squarely.


texts: Op amp current noise reduced by putting pressure on signal cable

texts:
I have a ribbon cable that is carrying four signals (each about 5V in amplitude and 1-2 Hz) and a ground wire between a DAC and four op amps.
The op amp outputs are amplifying the signals to 30 V and dropping across really substantial 5 Gohm resistors.
Because the load is so big, I'm using a current multiplier (model Keithley 427) to check that the current is following the voltage in the resistor. The output is fairly noisy as you can see in the attached image. The weird thing is, the noise on the output of the current amp is reduced if I press on the ribbon cable that's carrying the signals from the DAC to the op amps. In the last plot, you can see the noise is a lot less around the 4.5 s mark where I start pressing on the cable.
The noise is barely there for smaller loads as you can see in this picture of the current multiplier output for a 3 Mohm load
The ribbon cable is unshielded, so I thought it was possible by pressing the cable onto the metal table, I was blocking some interference or capacitive effect between the wires or from the environmental noise. I tried adding some homemade shielding by wrapping the cable in aluminum foil and electrical tape and grounding one end of the foil, but it didn't produce a noticeable difference.
The wires are quite thin (AWG 28 I believe). I have heard some people say that for high frequency AC, you should place a ground wire between each signal on the ribbon cable, but I'm not sure it would do anything for signals in the 1-10 Hz range. I'm quite sure that the connections between the wire ends and their anchor points are solid.
Any ideas you have for why putting pressure on a ribbon cable would reduce current noise for small currents would be greatly appreciated.


texts:
I ordered a Type A USB port because I thought all Type A USB ports were the same, come to find out after taking the laptop completely apart that the 4 prong 2.0 USB port I ordered was way different than the type A 2.0 USB I needed for the laptop, So I took apart a flash drive and that's also way different than the other 2

The one I order on amazon is the same size as the one I needed for the laptop, but the very end of the new one where the prongs are isn't recessed to go half way into the logic board

Does anyone know where I can find laptop Type A USB ports for a HP G7
you can probably tell that the one i need is the one closest to you and the one i ordered is the one furthest away


texts: Why is this considered a slow logic level shifter?

texts:
I'm working on a project where I have to do some unidirectional logic level shifting. I'm not able to get any chip to do it at this moment (it's late at night) so I looked up some DIY solutions and came across this design(Method 1) i.e. a potential divider. The warning associated with it confuses me however.

  This method works for slow signals, but it’s not very reliable.

My question is why won't it work for slow signals? It's just a voltage divider so there's no lead/lag components or setup and hold times for logic gates. If anything it should better with slow signals, but why not?


texts:
I'm working on a project in which an arduino should emulate a thermal printer.
I'm currently using an Arduino UNO R3 board with ATmega16U2 controller to handle the communication between USB and the ATmega328 microprocessor.
I used the FLIP suite from ATMEL to erase the firmware in the ATmega16U2 and reprogrammed again with the arduino firmware.
Which are the steps to take in order to make the board appear in the computer as a USB printing support? Is there any firmware available? What I need is basically to be able to use the arduino board with a standard windows printer driver and to catch the messages sent to the emulated printer.
I checked out the LUFA library but I do not have it clear how to use it.


texts: How can I confirm the correct pinout of a USB  RS232 null modem cable?

texts:
A loopback test with HyperTerminal, or something similar, will confirm the cable itself is working.

But I want to know if the pinout configuration is indeed as expected... i.e. That pins 2 and 3 are reversed.


texts: How to simulate a simplified model of crosstalk effect in LTspice?

texts:
How can I make simple model and simulate the crosstalk between two adjacent channels of a multiplexed DAQ inputs? I observe that in its most exaggerated form, a nearly exact duplicate of one channel appears on an adjacent channel to which nothing is connected. I need to demonstrate in LTspice or any simulator that both sampling rate and the load impedance has effect on the crosstalk.

What I want to simulate that how the sampling rate and the load impedance effects the crosstalk on the other channel. Im a bit confused how I can model and see the coupling effect between channels.


texts:
So I'm trying to create a OVP using TL431 an a triac, i have checked the datasheet but since i suck at math i don't really get how to set the ref voltage..

datasheet: http://www.ti.com/lit/ds/symlink/tl431b-q1.pdf

My example circuit:

I'm having a 19v power supply, and i want to make it so that if the supply for some reason should reach over 20v, it blows the fuse.. Any tips? Thanks!


texts: Is it possible to blink an LED with just a USB data cable and a transistor?

texts:
Sorry if this is a dumb question, I am new to electronics and was looking at diagrams of USB cables and wondered,

"Could you use the low voltage data wires on a usb and a MOSFET or something to control the voltage from the higher voltage wires to make an LED blink on and off?"

I have been searching online and could not find much (maybe that's a bad sign) I have a cable that splits the 4 usb wires and connected them to a bread board and can turn on the LED with the +5V and -5V wires, but I'd like to know if I can use the other wires to control it?

Any advice is appreciated! Thank you


texts: Why can't I drive more than one H-Bridge unless all other output pins are in Hi-Z state?

texts:
I've looked at other questions, this one came the closest, but my problem is not in terms of power supply.
To drive multiple DC motors from an Arduino Mega 2560, I got a few HG7881-based dual H-bridge drivers. Looking at the datasheet of that chip, they seem to be sufficient. Testing the motors with my bench supply at 9V, they never reach 400mA when stalled, which is still far below the typical continuous output current of 600mA.
When I drive just a single motor through one of these H-bridges, it works 100% fine, even PWM mostly works, down to about 30% duty cycle.
However, once I connect a second H-bridge to two more pins of the Arduino, and just set those to OUTPUT, the motor stops working:
int motor0_forward = 2;
int motor0_backward = 3;
int motor1_forward = 4;
int motor1_backward = 5;

int led_pin = 13;

void setup()
{
    // Set up motor 0
    pinMode(motor0_forward, OUTPUT);
    pinMode(motor0_backward, OUTPUT);
    digitalWrite(motor0_forward, LOW);
    digitalWrite(motor0_backward, LOW);

    // Set up control LED
    pinMode(led_pin, OUTPUT);
    digitalWrite(led_pin, LOW);

    // Set up motor 1
    // Everything works if these four lines are commented out!
    pinMode(motor1_forward, OUTPUT);     // ???
    pinMode(motor1_backward, OUTPUT);    // ???
    digitalWrite(motor1_forward, LOW);   // ???
    digitalWrite(motor1_backward, LOW);  // ?*/
}

void loop()
{
    // Blink control LED
    digitalWrite(led_pin, HIGH);
    delay(50);
    digitalWrite(led_pin, LOW);

    // Test motor 0
    digitalWrite(motor0_forward, HIGH);
    delay(50);
    digitalWrite(motor0_forward, LOW);
    digitalWrite(motor0_backward, HIGH);
    delay(50);
    digitalWrite(motor0_backward, LOW);

    delay(500);
}

Instead of commenting the lines out, I can also set the pinMode to INPUT to get the pins into Hi-Z, and that is the workaround I am using in my actual program.
However, I would like to understand what's going on here.
I have the on-board LED blinking to make sure there's no brown-out or reset happening, and it blinks steady in short pulses, so no issue here.
As the outputs for motor1 are set to low, the connected motor is not driven. The load should at maximum be 20mA, according to the datasheet, but none of that should be supplied by the Arduino. The lab supply shows ~43mA current draw, which seems a little higher than advertised but still ok for two H-bridges. So I'm fairly certain that there's no overcurrent situation on the Arduino itself.
I tried using two separate boards, no difference. I tried using other pins, even pins without PWM output, no luck. I tried putting in series resistors to limit the current somewhat, but the highest I got with a single motor still working was 330R, and that didn't solve the problem either.
What does work is disconnecting the motor1 H-Bridge from the Arduino physically. When I do that, motor0 immediately starts moving again. With an analog oscilloscope, I could confirm that the signal sent out on the motor0 pins by the Arduino does not change whatsoever between motor1 being connected or not.
So, what the hell is going on here? What else can I check?


texts:
I am redesigning an input interface circuit for digital input. Its a basic signal conditioning circuit for reverse polarity protection, EMI ESD protection, and filtering voltage surges. For EMI EMC, ferrite beads are used in previous design.
How can the use of smd ferrite-bead be avoided by using apt PCB designing techniques, still keeping the PCB immune to electromagnetic interference.


texts: how do I change baud rate for bluesmirf without connecting to pc?

texts: Hi I have the sparkfun bluetooth mate silver. I am trying to start working on control via bluetooth for my Arduino. Only thing is I need to set the baud rate for the bluetooth mate, all guides I can find on the net show how to change it via pc. I do not have bluetooth connectivity on my PC. Is there a way to do it via the Arduino?


texts: What is the mathematical relationship between MOSFET switching frequency (motor speed control) and motor speed in rpm?

texts: What is the mathematical relationship between the switching frequency of MOSFET in a three phase motor controller (induction motor and BLDC motor) and the speed in rpm of the motor shaft?


texts:
First and foremost, I would like to point out that I am a beginner in electronics.

I have designed a board that is meant to be connected to 240V AC. However, there is a relay on it that has a 12V DC coil. This means that I have to physically bring DC over to this board and I have selected a Molex KK254 two pin connector for this purpose. It sits pretty close to the relay and there is enough enough clearance on my PCB (at least 4mm pretty much everywhere) but I am still worried about AC finding its way to it. The  DC supply is also nearby and powers delicate electronics.

Here is the schematic (it's pretty straightforward. Also, the "AC Phase Output" is fused later down the line):

And here is the current PCB layout (NB: there are no copper filled zones/pours, picture updated 20/4/20):

As you can tell, I have already made a T cut to separate DC from AC at the relay to make the creepage distance larger.

The smallest distance (clearance) between AC and DC is 9-10mm (.35 inch). Is this enough to protect the DC supply or should I add more components (i.e. a Zener Diode?)?

Thanks in advance for your suggestions.


texts: Attenuation in the circuitry of differential vs isolated probes

texts:
Using this website as a reference for differential probes:
https://circuitcellar.com/research-design-hub/high-voltage-differential-probe/

By Andrew Levido, Circuit Cellar
The differential probe is described as attenuating the entire common input mode range down to what can be accepted by the differential amplifier, resulting in milliVolt levels for the signal of interest whose difference would then need to be re-amplified relative to GND to suit the desired output range.

Now, if the same probe was isolated (isolated output to be-specific), it would not need to attenuate the entire-common mode input range. Since it would float to the level of the signal of interest, you would only need to attenuate the range of the signal  of interest to a range that could be accepted by the amplifier.

Other than the cost of isolation, is there any performance drawback that I am not seeing for the isolation amplifier in favour of the differential amplifier?
The context of my question is I need to make a rather general purpose analog input to a microcontroller and for safety purposes, I was going to isolate it anyways. The plan was to run the ADC running off an isolated source and communciate with the microcontroller through an isolator. It then occurred to me that if it was isolated anyways no re-amplification would be required like the differential probe method. Since I have control of the ADC and can easily make it isolated, I'm not seeing much of a point with the differential probe method where the entire common mode input range is attenuated and the tiny signal difference is then re-amplified referenced to ground.
Is the existence of the differential probe method just a cost issue? Or when one does not have the choice of floating the ADC? I'm not seeing any benefits to it for my usage case if I'm planning to isolate the ADC anyways.


texts:
When using the RF what is the difference of Wide band and Narrow band communication?

Most ICs claim to use Narrow band and I have not come across ICs that use wide band communication. Is there a reason for this? What are the applications wide band is more applicable?

Thank you for your opinion.


texts: What component should I use to build my own servos?

texts:
I want to create an array of linear actuators for an art installation.

The easiest thing for me would be to send a PWM for each actuator. I think of using chips like TM1809 or WS2811 those chips are found in LED strips, you program one with the desired PWM outputs (9 outputs for the TM1809, 3 for the WS2811) and the chip hold these values until next change. These chips are serializable so you can generate thousands of PWM with one SPI output and refresh 50 times per seconds (this is how big LED screens works).

I thought of using motorized faders found on mix control surface (like these). They are fast enough, small and quite reliable. They have one servo track to read current position and a motor but they come without microcontroller so I have to add controller on them.

My question is what chip could I use to control the motor and correct position according to input PWM and current sensor position? It's exactly the role of the controller in a servo. Filter PWM input, read it, then control motor position with PID. Does anyone know which cheap component I could use for this ?

Is there any PID chip supporting on the fly parameter change for Kp, Ki, Kd ?


texts: Is it possible to modify a 5 lead unipolar stepper motor to a bipolar?

texts:
I would have a question regarding to 5-lead unipolar steppers, I just found in a scanner a unipolar stepper motor with 5 wires and it has a nice gearing on it, so I would like to modify to a bipolar stepper. The stepper motor is TYPE 4H4018S2001 12v 0.4A TECO Made in Taiwan.  I took a picture and did a little drawing with the numbers on the coil ends. Could you tell me how to modify it to a bipolar stepper : https://dl.dropboxusercontent.com/u/7511244/unipolar_tepper.pdf
 I cut the plating on the PCB and found which pair of coils could be separated :

wire 7 with wire 3 - ends of two coils;

wire 2 with wire 6 - ends of two coils;

wire 1 with wire 5 - ends of two coils;

wire 8 with wire 4 - ends of two coils;

How should I connect in the right way to get only 4 ends?


texts: ATSAMC21 - CAN configuration - Nominal bit timing vs. data bit timing & time quanta calculation

texts:
I'm trying to configure the CAN bit rate of an ATSAMC21 to 125ksps in a CAN2.0B configuration.
However, after reading through the datasheet, the ASF documentation and the ATMEL start help I'm confused.

I got mainly 3 questions:

What is the difference between "Data bit timing" and
"Nominal bit timing". <-- For this part of the question I already figured out the answer. Please see my own answer below.
How is the time quanta/bit rate calculated?
How to set up the ATSAMC21 CAN module as CANV2.0B with 125ksps while using a 8Mhz CAN clock?

Background for question 1)

In ATMEL Start, these settings look like this and there is:

The datasheet does specify 2 different registers for this as well, but I don't find any clear explanation what's the difference and which one is used when. Also, a thorough google search and going through diverse www.avrfreaks.net threads did not bring any light into that matter.

This is page 706 of the datasheet showing the data bit timing.

This is page 713 of the datasheet showing the nominal bit timing:

Background for question 2)

On page 707 the datasheet shows

On page 706 the datasheet shows

However, this confuses me. With a 8Mhz clock and a Prescaler of 1, I would calculate the bitrate like Datarate = 8Mhz / Prescaler / (Phase_Seg1 + Phase_Seg2).

With the data shown in ATMEL start and also with the initial register value in the datasheet this results in 8M/(11+4)=5.333ksps. <- What am I missing here?

After digging around on the Microchip product page of the ATSAMC21 I found this APPNOTE which got me even more confused. On page 4 this document describes, how to calculate the bit rate and it even uses the Data resynchronization jump width into the calculation. If I calculate the above example with the Jump width the data bit rate results in 8M/(11+4+4)=4.21ksps.

This is page 4:


texts:
I'm using the HT12D remote control decoder (and HT12E remote control encoder) to send some data using RF and I have done so successfully.

Now, I want to operate a relay depending on the output of one of the HT12D's output pins (suppose that pin is called 'D8')

I read in this forum thread that in order to do that I need to build a "transistor drive". I followed the same pattern that is suggested in this thread.

But unfortunately it doesn't seem to be working. My guess is that the problem is that I'm using a different transistor (I'm using 2n5550).

I wanted to ask 2 questions:

Is that really the problem?
Is is possible to make it work with the 2n5550?

Just to make sure, my connections are as follows:
(same as described here)

D8 -> 10K resistor -> base pin of the 2n5550
2n5550 emitter to ground
2n5550 collector to relay
5V to relay


texts: Sawtooth VCO and current source for modular synthesizer

texts:
I have been working on a current source and sawtooth core VCO based on the Electronotes/Aaron Lanterman/Ian Fritz designs/ideas.

I have breadboarded out the attached VCO schematic; the transistors are an NPN array on a 3086 IC. The transistors I've used are the matched pair on the chip. Some of the resistors are trimmer or pots on the BB also but are resistors in the schematic.

I have found that the frequency of oscillation is too high (>100KHz sometimes). I also have found that the oscillator decreases in frequency over time and sometimes just abruptly stops.

The components in the schematic are approximations to some things I have tried on the breadboard to bring the frequency down to approx 50Hz - 2000 Hz, controlled by the value of the voltage into U1.

I am confused about how to derive an expression for the frequency of the sawtooth wave at output at U3.

For instance, I see the rate of charge of the sawtooth wave to be the rate of current sunk from the inverting input of U3 multiplied by R3. Of course, the output of U3 will charge until it reaches the reference voltage of the inverting input of U4. To decrease the frequency of the ramp charge, I have tried lowering R3 and increasing Rlimit (to reduce the current sunk from the oscillator). However, this has not worked. I have also tried increasing Rref to limit the current drawn by the current source. This has helped, I think.

Can anyone suggest a way that I can decrease the frequency?

Also, the oscillator tends to decrease in frequency over time, and I have not detected yet what component is responsible for this. Do you have any thoughts on this? I thought it would be connected to the transistor pair, or something temperature dependent. I am also using a temperature compensated resistor for the first inverting op amp.

Please let me know if you have any thoughts on this. I bet many of you have worked with similar designs.


texts:
I have trouble understanding what's critical path delay of n-bit Ripple Carry Adder. In the book I read, given N-bit Ripple Carry Adder formed from N single 1-bit full adder:

  the critical path delay is 2N

I know that for each single 1-bit full adder, the Cout(Carry-out)-delay is 2 and the Sum-delay
is 3, from this observation why the critical path delay is not 2(N-1)+3 = 2N+1 (I mean the last one is calculated with Sum-delay instead of Cout-delay)? So assume that these 1-bit full adders are denoted by A(0) to A(N-1), the critical path delay is from Cin(A0) to Cout(A(N-1))? So I should not substitute the last one with Sum-delay?

  the delay to get the sum (Sum delay) is 2N+1

I can understand this one, since now 2(N-1)+3 = 2N+1 should work, but isn't that this implicitly assumed that the last 1-bit full adder will be the slowest one? (You may skip this one if you want since my main focus is 1.)

Edit: I found a YouTube video explains why I mean, but I don't what whether he mean critical path delay.


texts:
I am working on Arduino board for a while. One thing I do not get is why there is a chip called "USB to serial adapter" on Arduino board.

Isn't USB already serial. What does it mean USB to serial? Is it about voltage regulation only?


texts: Identify black component in Gopro 3 silver

texts:
Can anyone tell me what this component with a red square around is?

As you can see, the one right next to it is burned, and I would like to replace it.

I have attched a schematic of the Black PSU it goes to.

I gave my gopro 12v instead of 5v :(


texts: what's the reason for this noise in the SMD transformer

texts:
I am trying to repair the power supply of the sewing machine. This card I think, which is in SMPS structure, is an LCC Resonant feeding card. I have repaired this board and I get the output voltages healthy. When I plug in the 220 AC sockets from the card's input points, there is a buzzing sound from the small transformer. When I searched a bit on the internet, I learned that they called it "coil whine". The system works well, but this noise gets even more severe, especially when the card's output pins are open. I am affraid of exploding this power board.

I added a video (the video link) to better explain what I wrote above.

in the first case:

card's outputs are open and energized. There is a noise,

in the second case

When I put a magnet on the transformer, the sound is cut off. I saw this in a video. However, this is decresing the output voltage 24v to 12 volt. I think this transformer goes to the mosfet's Gate.

In the third case,

I plugged a fan into the 24 V outlet and again the noise was gone and the system works healthy. What is the reason for this noise and how can i fix it?


texts: Controlling Voltage Range from Sensor Signal

texts:
I have a project where I would like to control a range of voltage outputs from a sensor signal.  In this case, taking a signal that is 0-10 volts, and using some method to only allow the range of 4-6 volts to "pass" through. All voltages below 4 and above 6 would read as 0.  Or in another case, for example, only allow voltages from -1 to 1 volts to "pass" through, while voltages -10 to -1 and 1 to 10 read as 0.

On top of that it would be beneficial to be able to lower that range by using some type of voltage divider with a potentiometer, for example, making the range 4.5 to 5.5 volts.

The goal is to have an adjustable deadband.  Normally when the sensor reads 5V, there is no actuation. I want to make it so I can control the no actuation range, i.e. from 4-6 volts there is no actuation. I want to do this with just analog circuitry.

I have thought of zener diodes and tried different op-amp scenarios but have not discovered anything yet.

Any ideas? Snippet of relevant circuit.


texts: 3 phase AC line voltage mismatch reasons

texts:
Suppose, I have 3 phase AC line and neutral wire. Voltage between each phase and neutral 220V, voltage between any 2 phases 380V. If newtral wire has poor contact(hight resistance), when I connect load (about 1 - 2 kW) between one phase and neutral wire, voltage on this phase decreases from 220 to 160 V. And on others 2 phases voltage increase from 220 to 250V. Can you explain, why bad contact on neutral wire causes voltage mismatch?

PS: I found some vector diagrams, showing this mismatch:


texts:
I am an engineering fresh graduate with an interest in PCB design. I have been learning KiCAD which is really fun and I enjoy it alot.
A friend came to me with the reference circuit attached here and said he has this smps but needs a smaller design.

I have made the schematic of it. Its a 100-230VAC to 12V-10ADC power supply.

I have a few concerns which are:

Even though the schematic is complete, I want an expert opinion on it. Also it feels like its hard to read for someone how doesn't have the reference circuit. How can I improve on the schematic drawing?
Although SMPS's are so so common, I could not find a proper documentation that help one in selecting the components to meet the required current and voltage measurements at the output. If someone can share a source or their precious knowledge, I would really appreciate.
Apart from the component selection, I am curious about the theory behind the working of SMPS. Why high frequency is needed, how the required output is achieved through signal processing and other things.

Lastly is this design ready to start making PCB?
Thanks a lot for your help..


texts: How to model a load as combination of RLC (resistance, inductance capacitance?)

texts:
I have a constant voltage DC power source and a load connected accross it.

The load consists of various sensors, modems, some small actuators, and something else which I don't know (mostly resistive.)

I want to model the behavouir of this load and see the current consumption in start, stop, and other operating conditions.

How do I model the load?

series RLC
parallel RLC
mix of the two


texts: For some reasons, i'd like to start my car at some specific times (e.g. from 11:00pm to 11:10pm, then from 5:00am to 5:10am). Are there any simple ways of achieving this? I thought of Arduino but I don't have much equipment at hand presently. Maybe a relay activated by two alarm clocks and a timer set on 10min?


texts:
My setup:

Common) CPU: at91sam7x512, JTAG: olimex-arm-usb-tiny-h, proprietary single-CPY board
1) Windows 7, OpenOCD 0.0.4     <- works
2) Ubuntu 13.04, OpenOCD 0.7.0  <- strange error

There are some config files written in past times and the windows version works. Now I am trying to make things work under linux.

The manufacturer's page doesn't seem to have a ready config file, although they have instructions for building OpenOCD.

I built it with ft2232 support. OpenOCD seems to locate the JTAG, but not the device:

sw3@pc90313-sw3:~/ocd_conf$ openocd -f ocdconfig.cfg
Open On-Chip Debugger 0.7.0 (2013-08-16-13:27)
Licensed under GNU GPL v2
For bug reports, read
    http://openocd.sourceforge.net/doc/doxygen/bugs.html
Info : only one transport option; autoselect 'jtag'
adapter speed: 20 kHz
srst_only srst_pulls_trst srst_gates_jtag srst_open_drain connect_deassert_srst
Info : device: 6 "2232H"
Info : deviceID: 364511274
Info : SerialNumber: OLWKRKY?A
Info : Description: Olimex OpenOCD JTAG ARM-USB-TINY-H A
Info : max TCK change to: 30000 kHz
Info : clock speed 20 kHz
fError: couldn't read enough bytes from FT2232 device (70 < 81)
Error: couldn't read from FT2232
Error: Trying to use configured scan chain anyway...
Warn : Bypassing JTAG setup events due to errors
Info : Embedded ICE version 1
Info : sam7x512.cpu: hardware has 2 breakpoint/watchpoint units

Here is my config file:

sw3@pc90313-sw3:~/ocd_conf$ cat ocdconfig.cfg
source [find interface/olimex-arm-usb-tiny-h.cfg]

adapter_khz 20

source [find target/at91sam7x512.cfg]

This error Error: couldn't read enough bytes from FT2232 device (70 < 81) seems to be the give-away. Other people in Googleland have experienced similar problems, but with (0 < 81) in which case it is clear that communication is not working at all. In my case, the number oscillates at 69-79-71.

Ideas?


texts:
I'm trying to mathematically model a Class E amplifier in the hopes of deriving a relationship between the input and output (Transfer Function).
One particular difficulty i'm facing is impedance matching the load to the rest of the circuit. The regular procedure would be to obtain the thevenin equivalent at the load, and the load impedance would simply be the complex conjugate of this. However in this circuit we have a switch with an inductor before it.
Therefore the thevenin equivalent would vary between the ON and OFF states of the switch.

Question:
How would you determine the thevenin equivalent, in the presence of a switching circuit?

I just need a starting point. How do you normally proceed in such cases?

simulate this circuit – Schematic created using CircuitLab


texts: How to build 200 Khz oscillator using Wien bridge?

texts:
I've the following circuit for generating sine wave.

As I'm supposed to make sine wave within 1 kHZ - 200 kHz, I chose wein bridge oscillator circuit. However, I'm not able to increase the frequency, even though I calculated it with the following formula: \$f = 1/2\pi RC\$. At the moment with current parameters, got 13 Khz frequency not any more, tried a lot with different parameters but couldn't get above that. Can you please, help or suggest different circuit where, could get the needed frequency? I have to make the sine wave generating oscillator using operation amplifier or transistors. Highly, appreciate if you could assist me!


texts: How to choose the right amplifier for 100 Ohm RTD in 3 wire configuration?

texts:
I have been doing research for the past week on setting up a 100 Ohm Platinum RTD to work with labjack U3 LV (I have to use labjack). I know I have to start off with a wheatstone bridge, and use a three wire connection since that is how many wires each RTD has.

For reference it is the labjack U3 LV. I could not post the link as the post would not let me.

This is what I thought the configuration would roughly look like. However I do not know if I need to add a differential amplifier, or an instrumentation-amplifier to obtain a good signal to labjack?

Below you'll see the typical InAmp with 3 op amps that I thought I would have to set up with my wheatstone bridge circuit.

However I don't even know how to begin choosing resistors for this, or how to properly set it up with the wheatstone bridge. The question remainds should I use this InAmp?

If neither of these would be suitable to obtain good readings from the RTDs then how should I set up my circuit? I am not very well versed in setting up circuits and much less using op amps. So if there is an alternative could you explain what it is, and why it should be used and how would I go about finding the resistors I would have to use for it to output a good reading, and the current that would run through it to obtain a good reading on the labjack? Actually I believe the current is 1 mA for most of the PT100's? Unfortunately I do not have the exact data sheets as this system has already been set up as is for years without use.

The version of the labjack that I have can handle 0 - 2.4 V and 0 - 3.6 V. (12 bit) Currently I am also not sure how I would power it, but I was thinking of using a DC Source like a small battery. I'd like to verify that I would need a voltage divider, and if so how would I go about incorporating it into the circuit?

I have been attempting to understand this set up, but the op amp part is what is confusing me the most. Since I know how to balance a normal wheatstone bridge, is there anything different I would do for this? Overall I'll be getting readings from 8 RTDs, but I figure once I figure out how to do one of them I can just do the rest of them the same way since they are all the same. For reference these RTDs are on heat pumps and will eventually be used in a GUI that will convert the voltage received on labjack to a temperature. All help is appreciated! Thanks!


texts: Common source circuit with current source and diode connected load

texts:
Could anyone explain why the output bias voltage of the common source in figure a is not well defined and needs a common mode feedback while the circuit in figure b is well defined?

Here is what I have so far.
For the circuit in figure a. When the bias current changes a bit, Vout changes a lot. However, how to explain the same thing for figure b?


texts: Simplest method to filter a PWM'ed sinusoid?

texts:
I am using PWM to dim a bulb and was wondering how I could restore the chopped waveform to a sinusoid whose amplitude varies with the duty cycle.

The switching frequency is 25Khz and the line frequency is 50Hz using a 25V transformer for the supply. The bulb is rated at 100W

To be honest, i don't really know where to start.

Should i be looking for off the shelf filters? or would it be better to design a configuration from a few capacitor and inductors?

I have found an example of a filter being used for exactly my purpose, but there is no information in the paper about the design of the filter elements.

Here is a simplified schematic of the circuit I am using.


texts: Mifare Classic 1K - Access Keys & Conditions

texts:
I am trying to update the access keys and access bits in Mifare Classic 1K card. My goal is to get the below behavior on sector 1 :

Put a custom KEY-A. should be able to read / modify it later (after authenticating with KEY-A)
The data in blocks 0..3 of sector 1  is RW using KEY-A only
No read or write access using KEY - B

Based on this, I am using the mifare classic calculator on page at http://calc.gmss.ru/Mifare1k/ to come up with the following.

Can someone confirm if I got it right? Pretty new to RFID


texts:
I need to create a interruption-proof power for a project of mine, very similar to the design of this link.

My problem is that I need to adjust the current delivered of the solar panel (21V, 1.2A) to 5V and simultaneously charge a battery 12V, 18Ah. If the solar panel does not supply power, the battery takes its place.

Does anyone know any circuit to do something? Or can someone give me a light as do something?


texts: Can I connect the ST Nucleo-F334R8 board using CAN (Controller Area Network)?

texts:
I have the ST Nucleo F334R8 board (64 pin version/LQFP64). The datasheet of its microcontroller (STM32F334R8T6), which is advertised as having one CAN interface - the 2.0 B Active type says this regarding 4 of the microcontroller's pins (on the sub-topic of 'Alternate functions'): CAN_RX (pins PA11 and PB8) and CAN_TX (pins PA12 and PB9).

However, I can't really find anything in the datasheet of the board concerning Controller Area Network. Can I use the CAN interface of the microcontroller or not? I would like to connect the Nucleo-F334R8 to a different board using CAN (in the first instance and LIN afterwards). Can I do that by using just a couple of CAN transceivers (MCP2551)?


texts:
I have a very old keyboard, a CASIO MA-100 that I want to convert to a MIDI keyboard:

Being a programmer and a digital electronics enthusiast, I know how to do it, but I could use some help to save time.

I guess the biggest issue is choosing a µC. Something with a USB interface* would be great, something that can also be powered by USB, even better. Then there's the issue of talking MIDI or MIDI-over-USB. I don't know how hard they would be, but I could probably do with some already written code there, too. (Unless they're very simple and don't need much testing.)

I looked around some electronics project sites this morning, trying to find some open source MIDI or MIDI-over-USB controller firmware, but couldn't.

I did find some Arduino projects, but a prototyping board seems a bit overkill for such a simple project.

The key matrix is 10x8 (10 select in * 8 data out), simple boolean logic, no velocity data. (Though two select lines are easily expendable.)

So I guess my simplest option would be a ~1 MHz µC with 8 input, 8 output pins and a serial buffer (+I/O pins) for MIDI. My best would be a project called "USB MIDI device firmware for Make SeriesXX microcontrollers."

Any ideas?

*: An easy USB interface, i.e. not PIC18. (Edit: This was a simple prejudice arising from the state of the organisation and documentation of the PIC USB framework a few years back. I guess it's time to break it.)


texts: When load increases in rotor of induction motor how does stator draws more current?

texts: When load is increased in the rotor , why does the stator draws more current since the rotor is short circuited. How does mechanical load increases the electrical current flow....


texts:
Problem: A simple current mirror is set up with two NPN transistors. \$V_{CC}=12\$ Volts \$+V_{in}= 30\$ Volts. Load resistance \$R_L\ =\  1\ K\Omega \$.
What is the resistance value interval for output transistor to stay in forward-active region and not to be deformed?
( \$V_{BE}=0.7\ V, V_{CE,SAT}=0.6\ V,\ V_{CE,MAX}=25\ V, I_0=I_R\$)

simulate this circuit – Schematic created using CircuitLab
What I have tried so far:
$$  I_{R} = \dfrac{V_{CC}-V_{BE}}{R}  $$
$$ I_{R}=I_C+\dfrac{2I_C}{\beta}=I_C \Big(1+\dfrac{2}{\beta}\Big)  $$
$$ \therefore I_0=I_C=I_R \times \dfrac{1}{1 + \frac{2}{\beta}}  $$
$$ I_0 = I_C = \dfrac{V_{CC}-0.7}{R}\times \dfrac{1}{1+\frac{2}{\beta}}$$
but I am stuck here since \$\beta\$ value is unkown could not take it further.
PS: I am not asking for a full solution.


texts: How to switch many (15) low power (40W) lightbulbs from a microcontroller?

texts:
The power rating on the bulb is the amount of power the PSU has to deliver in order for the bulb to light up the brightest right? Hence if it's a 40w bulb I need 40watts of power for it to light up properly right?

If so then my dilema is I have 15 or so light bulbs which need to be switched on and off invididually. The only way I can think of is using a relay but that means 15 relays!! It's turn on and off by a microcontroller which switches the relay on and off. I need to use bulbs because the person am doing it for insists on bulbs


texts: 'undefined reference to' errors trying to compile with Make

texts:
I had a working Makefile that successfully compiled and built a basic program to toggle and LED on my stm32-h103 board. I have since attempted to add and use FreeRTOS in my program. I have added in the FreeRTOS paths into my Makefile however I am getting the following errors when I run make.

src/app.a(startup.o):(.isr_vectors+0x2c): undefined reference to `vPortSVCHandler'
src/app.a(startup.o):(.isr_vectors+0x38): undefined reference to `xPortPendSVHandler'
src/app.a(startup.o):(.isr_vectors+0x3c): undefined reference to `xPortSysTickHandler'
src/app.a(main.o): In function `main':
/home/matthew/Work/22_ARM-Firmware/HomeAutomationControllerPrototype/src/main.c:36: undefined reference to `xTaskGenericCreate'
/home/matthew/Work/22_ARM-Firmware/HomeAutomationControllerPrototype/src/main.c:37: undefined reference to `vTaskStartScheduler'
collect2: error: ld returned 1 exit status

I am very new to Makefiles so am unsure what else I must add to get the code to compile.

My two make files are:

Makefile.common

TOP=$(shell readlink -f "$(dir $(lastword $(MAKEFILE_LIST)))")
PROGRAM=main
LIBDIR=$(TOP)/libs
FREERTOSDIR=$(TOP)/src/FreeRTOS/Source

#Adust the following line to the library in use
STMLIB=$(LIBDIR)/STM32F10x_StdPeriph_Lib_V3.6.1/Libraries

#Adjust TypeOfMCU in use, see CMSIS file "stm32f10x.h"
#STM32F103RBT (128KB FLASH, 20KB RAM) --> STM32F10X_MD
TypeOfMCU=STM32F10X_MD
#STM32F103RET (512KB FLASH, 64KB RAM) --> STM32F10X_HD
#TypeOfMCU=STM32F10X_HD

TC=arm-none-eabi
CC=$(TC)-gcc
LD=$(TC)-ld -v
OBJCOPY=$(TC)-objcopy
AR=$(TC)-ar
GDB=$(TC)-gdb

INCLUDE=-I$(TOP)/inc
INCLUDE+=-I$(STMLIB)/CMSIS/Include
INCLUDE+=-I$(STMLIB)/CMSIS/Device/ST/STM32F10x/Include
INCLUDE+=-I$(STMLIB)/CMSIS/Device/ST/STM32F10x/Source/Templates
INCLUDE+=-I$(STMLIB)/STM32F10x_StdPeriph_Driver/inc
INCLUDE+=-I$(STMLIB)/STM32_USB-FS-Device_Driver/inc
INCLUDE+=-I$(FREERTOSDIR)/include
INCLUDE+=-I$(FREERTOSDIR)/portable/GCC/ARM_CM3
INCLUDE+=-I$(TOP)/src

COMMONFLAGS=-g -mcpu=cortex-m3 -mthumb
COMMONFLAGSlib=$(COMMONFLAGS)

#Commands for general Makefile and src Makefile
ifeq ($(OptSRC),0)
    COMMONFLAGS+=-O0
    InfoTextSrc=src (no optimize, -O0)
else ifeq ($(OptSRC),1)
    COMMONFLAGS+=-O1
    InfoTextSrc=src (optimize time+ size+, -O1)
else ifeq ($(OptSRC),2)
    COMMONFLAGS+=-O2
    InfoTextSrc=src (optimize time++ size+, -O2)
else ifeq ($(OptSRC),s)
    COMMONFLAGS+=-Os
    InfoTextSrc=src (optimize size++, -Os)
else ifeq ($(OptSRC),3)
    COMMONFLAGS+=-O3
    InfoTextSrc=src (full optimize, -O3)
else
    COMMONFLAGS+=-O3
    CFLAGS += -D RELEASE_PUBLIC
    InfoTextSrc=src (full optimize and readout protected, -O4)
endif
CFLAGS+=$(COMMONFLAGS) -Wall -Werror $(INCLUDE)
CFLAGS+=-D $(TypeOfMCU)
CFLAGS+=-D VECT_TAB_FLASH

#Commands for libs Makefile
ifeq ($(OptLIB),0)
    COMMONFLAGSlib+=-O0
    InfoTextLib=libs (no optimize, -O0)
else ifeq ($(OptLIB),1)
    COMMONFLAGSlib+=-O1
    InfoTextLib=libs (optimize time+ size+, -O1)
else ifeq ($(OptLIB),2)
    COMMONFLAGSlib+=-O2
    InfoTextLib=libs (optimize time++ size+, -O2)
else ifeq ($(OptLIB),s)
    COMMONFLAGSlib+=-Os
    InfoTextLib=libs (optimize size++, -Os)
else
    COMMONFLAGSlib+=-O3
InfoTextLib=libs (full optimize, -O3)
endif
CFLAGSlib+=$(COMMONFLAGSlib) -Wall -Werror $(INCLUDE)
CFLAGSlib+=-D $(TypeOfMCU)
CFLAGSlib+=-D VECT_TAB_FLASH

And my src Makefile

# src Makefile

include ../Makefile.common

OBJS+=startup.o
OBJS+=main.o

all: src

src: app.a

app.a: $(OBJS)
    $(AR) cr app.a $(OBJS)

.PHONY: src clean tshow

clean:
    rm -f app.a $(OBJS)


texts: Why are state variables sufficient to describe the exact future temporal dynamics of a system

texts:
I'm confused about state-space state variables. How come knowing the initial conditions with the input 'determine completely the future behavior of the system'? From such knowledge, I can only approximate the 'next' state at 0+dt...
Also, how come knowing the designated n state variables at an arbitrary time t with the input suffice? It seems to me that there is an assumption that the highest order derivative vanishes?
For example, a one-dimensional moving ball system. At rest, this ball has a position x_0 and so only requires one state to be described fully. A constant speed moving ball needs one more state, namely the velocity. Now also if the velocity is changing, we need an additional state and so on. I understand this logic where knowing the highest order state allows us to climb down in knowing the lower order states one by one...For other systems, however, highest order derivates aren't necessarily constant, and so the even higher don't vanish.
I probably have some ideas gobbled and mixed up that need fixing.
Picture Source: Ogata's Modern Control Engineering


texts: Arduino RFID-RC522 can't read all rfid cards

texts:
I just got my RFID-RC522 reader & writer. It came with a blank white RFID card and a tag. Both of them prints out the data. But when i try my other cards at home that are also RFID cards then they don't work.
It prints out the Card UID but and the first sector and starts spaming:

  pcd authentication() failed timeout in communication

I used miguelbalboa/rfid library from GitHub and i used the Dumpinfo example. The RC522 works but not for other cards. Is there a limitation on the RC522?


texts: PID : What does « ultimate gain Ku » in Ziegler–Nichols method mean?

texts:
According to the PID controller Wikipedia page, in its subsection Ziegler-Nichols method, as in its Ziegler-Nichols page, it is said that using "ultimate gain Ku" could help to tune a PID.

Unfortunately, I'm not sure that I understand well what is the "ultimate gain Ku".

Is the "ultimate gain Ku", the highest value that could reach the system?

Or, is the "ultimate gain Ku", the largest error value between the targeted value and the value delivered by the system?

For example, if we want to target a value of 17 volts, and if we want to accept only a maximum of 24 volts, which means the highest error will be a positive +7 volts, is the "ultimate gain Ku": 24 volts ? or 7 volts?


texts: Where exactly does the power company cut my power when I fail to pay my electric bill?

texts:
I only have a somewhat vague understanding how the electrical grid works. I know the basics of energy production, and that the electricity comes to our homes using power lines resting upon those big supports we see everywhere. I would imagine the grid somehow splits into smaller sections like a tree whose endpoints are the final destinations, such as single apartments.

Let's say I fail to pay my electric bill and the power company decides to cut the electricity to my apartment. At what point of the grid is the electricity cut? The company knows my name and my address; so is there some kind of switch in my apartment building with my apartment number in it that the company comes to open? This is unlikely, since how would the company know somebody doesn't go and flip the switch again? Do they somehow control the flow of electricity from the power station? This is again seems unlikely.

Then adding to my confusion is the fact that there are of course multiple power companies, but there seems to be only one electrical grid. How does the company for which I'm paying the bill know that electricity produced specifically by them reaches MY apartment?


texts:
i want to send some signals on the 433 MHZ band.

Now i've bought a device (CDT-88) and it says 315/433 MHZ

(RF Wireless Transmitter Module 315 of 433,92 MHz CDT88)

after some searching i see a lot of sites where that frequency combination is used together.

Now i wonder: what does that mean? do i send at both frequencies?

What you might have guessed: it does not produce the desired result yet :-)

EDIT:

does it matter when i send at 315 mhz and the receiver is at 433? (it sounds like a yes, but i'd better be sure)


texts: Observing effect of household appliances on powerline communication

texts:
I had been recently working on Powerline communication modems (PLC). I put two PLC modems at different parts of my home and observed the data transfer rate between them. However, I observed that when I turned on an appliance in a home, I could see that there is a significant drop in the observed data rate. This should be attributed to the interference caused by turning on the appliance.

The following figure, which I also used in a poster that I recently published containing the same, shows the impact of different appliances on the data rate between the two end node.

The experiment involved turning on an appliance for 60 seconds and then turning it off for 60 seconds.

I was now trying to understand why such a behaviour was happening. So, went to the PLC modem manual and studied a bit. The PLC modem uses HomePlugAV standard and thus communicates in 2-28 MHz. I was able to observe the same on my spectrum analyzer, as shown below. Y axis is in dBm and X axis in Hz. The spectrum when PLC operates is clearly visible in the range of 2-28 MHz.

However, next when I put an appliance in parallel (emulating the setup when PLC communication rate would drop in home, when an appliance was turned on), I could see no change in the spectrum. What I was expecting to see was a distinct spectrum on the spectrum analyzer- maybe some frequencies get chopped of. My reasoning was that there could be 2 things affecting PLC rate:

Attenuation caused by appliance switching
Interference caused at particular frequencies by appliance switching

However, I am not able to quantify either of the two from my spectrum analysis. So, my question is: How can I find out what causes the rate to drop. Previous studies on narrow band PLC attribute this to interference caused by operating appliances as shown in the figure below.

I am unable to see such a change on my spectrum analyzer however. So, my questions would be:

Is this principally a correct way to measure the desired phenomena- drop in rate vs interference?
Am I doing something wrong that my spectrum analysis does not show such effects?
Is there a simpler way to measure this phenomena?
Is the frequency domain analysis sufficient?

To sense the powerline, I am using a 60 kHz HPF with 50 ohm matching impedance. Other thoughts on the experiment also welcome.

Possibly related: How can power line devices be affected by a power supply?


texts: Are all USB controllers kept at host side?

texts:
I see a lot of USB controllers in battery charging circuits. They have USB host controllers, embedded controller and  USB port controller at host side. (Refer tps2547 )

Can somebody tell me  what are the minimum control and protection circuits needed for charging using USB?
Is it the sole responsibility of the host to ensure reliable power to whichever device it is powering ? Is there any protection or control circuitry at device side, say load switches or similar kind?

Iam lost in the vast pool of resources with so many standards and specifications. Please note that Iam primarily looking for power transfer through USB.


texts:
I am reading "Advanced Thermal Management Solutions on PCBs for High Power Applications":

https://ats.net/wp-content/uploads/2014/04/Advanced-Thermal-Management-Solutions-on-PCBs-for-High-Power-Applications_APEX2014.pdf

And on page 4 is states that:

  It can be seen that the thermal vias are situated in the extended
  thermal pads beside the pad, where the component will be placed. So,
  to avoid the well-known problem of solder soaking, it is not possible
  to place open thermal vias directly underneath a component.

I have never heard of "solder soaking", can someone please explain what the author means?

EDIT:

I found something called "Solder voiding" in another document which seems to be the same thing:


texts: EEPROM Read Operation Always Returns 0xFF

texts:
I'm working with a AT24C04 EEPROM which communicates with a LPC1768 MCU on a I2C bus.

I try to write a 8 bit data (0xF0) on the 0x00 Address of the memory but when I want to read the content of this address, EEPROM returns 0xFF instead of 0xF0 which means nothing is written on this address.

It seems I have no problem in reading the EEPROM but there is something wrong with write operation.

My compiler is uVision v5.28 and here is my code:

uint8_t DeviceAddress = 0x50;
uint8_t TxBufferByteWrite[2]={0x00,0xF0};
uint8_t RxBuffer[1];

I2C_Init(LPC_I2C1, 100000);
I2C_Cmd(LPC_I2C1, I2C_MASTER_MODE, ENABLE);

//Byte Write
I2CTransferConfig.sl_addr7bit = DeviceAddress;
I2CTransferConfig.tx_data = TxBufferByteWrite;
I2CTransferConfig.tx_length = sizeof(TxBufferByteWrite);
I2CTransferConfig.rx_data = NULL;
I2CTransferConfig.rx_length = 0;
I2CTransferConfig.retransmissions_max = 3;
I2C_MasterTransferData(LPC_I2C1, &I2CTransferConfig, I2C_TRANSFER_POLLING);

//Current Address Read
I2CTransferConfig.sl_addr7bit = DeviceAddress;
I2CTransferConfig.tx_data = NULL;
I2CTransferConfig.tx_length = 0;
I2CTransferConfig.rx_data = RxBuffer;
I2CTransferConfig.rx_length = sizeof(RxBuffer);
I2CTransferConfig.retransmissions_max = 3;
I2C_MasterTransferData(LPC_I2C1, &I2CTransferConfig, I2C_TRANSFER_POLLING);

if( RxBuffer[0]==0xF0)
PrintS("Memory Working");

Thanks in advance.


texts: Dummy Load to test a 200 watt 24 volt supply

texts:
I feel like I have a simple question that hopefully can be answered quite quickly. I have a 24V power supply that is supposed to achieve a max output of 200W. Recently, I have reason to believe that the supply has gone bad, and rather than damage anything down-line from this supply, I want to test the output with a dummy load.
Currently, I have just been making a dummy load by wiring a bunch of resistors in parallel, which gives me one net resistance of 13ohm (~45W of power). Ideally, I would like to make a dummy load that will cause the supply to consistently output ~80W of power. I feel like the bundle of resistors is really cumbersome, and that there is an easier way to do this, I am just unsure because I am a novice.
If anyone knows an easier way to make a dummy load that can undergo up to 200W, and is less cumbersome that would help me out a lot. Thanks!


texts: How to calculate battery capacity from its size?

texts:
If the battery is for example 3.5mm x 14mm x 20mm and is 3.7V  what is it's capacity?

How accurate can such calculation be?


texts: LM3915 to drive more LEDs / basic questions about PNP transistors in saturation

texts:
As a few others here, I'm trying to drive a few (10) LEDs from each output of a LM3915 vu-meter chip. I've read different posts, and it seems the universal recommendation is this great answer.

I have, however a few difficulties understanding it in details to adapt it to my configuration (V+ = 9v, 5 rows of 2 leds). How are there R1 and R2 resistors choosen ? I see you want to reach 2mA, but I'm not sure about how to translate this to the resistor values.

I also guess the LM3915 is a specific beast here, as its output current can be configured (to drive LEDs directly without resistors for example). So in my naive mind, are these two resistors necessary at all, if the output current of the chip is configured properly ?

Also, is R1 only there to ensure that the transistor based is positive (instead of floating) when nothing is happening ? In that case, shouldn't its value be larger thaOr has it an additional purpose ?

I think I also have to ensure that (base current * minimal Hfe) > needed output current, or is this not applicable when the transistor is used in saturation ?


texts:
I'm designing a MIPI D-PHY interface, and the required nominel trace impedance for the differential signal lines (pcb traces) are 100 ohm.

Can I create 100ohm differential impedance, by using two 50ohm impedance traces, with a large spacing between the traces ?


texts: can we turn all radio signals to a single recieving antenna

texts:
Is it possible to turn all the radio signals to a single recieving antenna? Or,simply how can we receive all radio signals by
 a single recieving antenna.or is it possible to overlap many similar radio signals to enhance it's strength.


texts: Do USB Composite devices show up as one, or multiple devices

texts:
I'm working on a Composite USB device with HID + CDC device classes in one device. Things are not working 100% as yet, but irrespective op the details of my project, I just have a simple question.

Does a Composite USB devices show up as a single device os as multiple devices when plugged into a PC?

In other words, how many devices should my CDC + HID device show up as, in for example the Windows Device Manager, or my Mac's System Information?


texts: Connecting 3 12v batteries for a 24v system

texts: I currently have two 100AH 12v batteries connected to two 240 watt solar panels, I'm planning to buy an additional battery, how do I connect it to the other two?


texts: what is the best way to re-route multiple parts in same package and choose connectors with Diptrace

texts:
I am using Diptrace to route a board with over 1200 pins.

It's a fairly dense board with lots of SMD devices and I am using some resistor and capacitor networks, as well as dual MOSFETS and a large cable connector.

I have the luxury of using whatever connector on the cable I want, and the resistor and cap network pins are fairly interchangeable for me. For instance, they are all 10K resistors and I can exchange them for whatever other adjacent resistor or capacitor that is more easily routed.

So my question is when using Diptrace (or even in another package) to do the routing, is it acceptable or usual to just change the nets on the board when routing, or should I go back to the schematic and change the pins there and re-sync the layout with the schematic? Or is there a way to set Diptrace up
so that any pin can be used as long as the part is the same? How do you handle this? Or is there another better technique?


texts: Do resistors of same color code but different size have the same resistivity?

texts:
Picture has three resistors with the same color code (in this case brown-black-black) but different sizes.

My question is if they have the same resistivity because I know resistivity is indicated by color code.


texts: Can Emitter Follower BJTs work with large signal?

texts:
Sorry for such elementary question.

As anyone knows emitter follower design of BJT has some specifications . For example they are suitable for driving low impedance loads and so. But because the gain is less or maximum equal to 1, if one needs some degree of amplification, it should be done before ( at least it is what I think being rational) .

On the other hand BJTs are best suited for small signals. Please let me explain a little more by an example ( I am asked to be more specific in my questions! ).

Let's assume we have a 200 mV pk-pk signal and want to drive a 50 ohms load with 10 volt pk-pk. What I think is to amplify the signal to a 10v pk-pk first ( with Op-Amp/FET/ BJT or anything, it is not the matter here). Then I feed it to an emitter follower for impedance matching and obtaining enough current.

If we have a VCC=20v, now the input signal of the BJT in emitter follower design(10v) is not assumed as a small signal. This is a very common design and I can not understand how to manage it.


texts: How can I amplify cellphone's vibrator signal to switch my home electricity on or off?

texts:
I need to connect my Samsung s1 cellphone to my home's lights when I am away. I realised that I can use my cellphones' vibrator signal when I call my "Home" cellphone number. I know that the mentioned signal is less than 2 volts (I don't know exactly!) and to operate such a method, I need a relay to convert this low voltage into regular home electricity voltage (240V).
I tried to find a proper relay, but all what I find is that 5VDC relay from sparkfun:
https://www.sparkfun.com/products/100

Would you advise me if that would work fine with my requirement or not?
Is there any easiest way to do that?
What is your advice please?

NOTE: I have a slight knowledge in electronics!


texts: I have read that a design which fails signal integrity shall have EMC issues

texts: I have read that if a design has EMC issues and is emitting a lot of radiation, then there is a relationship with some signal paths not being properly terminated and/or there being signal integrity issues on the PCB. To what extent is this true?


texts: What is your go-to prototyping connector?

texts:
I have completed a few projects - sensors and an ADC circuit - and I find myself often connecting discrete boards together by tediously soldering wires to break-away headers like those below.

I worry about poor connections and the time it takes is excessive.

What are some good, flexible go-to prototyping connectors?  I am considering getting some RJ45 connectors and using old cat 5 cable, but they aren't 0.1" spacing friendly, which makes prototyping with them harder. (Do 0.1" compatible RJ45 connectors exist? Could I rig these up anyway?)

I realize this is highly dependent on the application but I was hoping to get a solution for the general case. Or maybe soldering ribbon cable to headers is the way to go.

For a little more information, my current projects have involved carrying a ~2v signal ~1m to an ADC, carrying 1MHz SPI ~0.5m between an ADC and a PI, as well as carrying around 3-5V power and ground - so nothing terribly fancy.

Update: I went with IDC connectors (2x5 pin and 2x20 pin) and I am happy with this decision.


texts: Diodes needed (parts) for OR gate automotive relay circuit

texts:
I need to power up a make-or-break simple automotive relay (4pin, 40A 12V) via an OR gate.

OR gate as follows:

Source 1 is the cable that provides +12V to activate car dome light which I will tap into and
source 2 is engine-on port from the busbar, obviously +12V when engine is on.

So if the dome light is on OR if the engine is on, the relay will activate.

I understand I
   need to put one way diodes on both my sources and connect them to pin
   85 of the relay.  What type of diodes I need to purchase?

EDIT  automotive relays have standardized pin numbers ie in this case a 4 pin relay has pins 30, 85, 86, 87


texts: Where to buy pin headers with non-standard pitch (1.5 mm)?

texts:
Recently I bought this graphic LCD from Mouser and I didn't noticed that the pin's pitch is not standard (2.54mm/0.1inch). It's 1.5mm. I don't want to solder this LCD directly on a PCB so I'm looking for a female pin header like this, but didn't find any until now.

Do you know where can I buy pin headers with non-standard pitch?
I usually buy my electronic parts from Futurlec or Mouser. I have preference for Europe distributors but China or USA it's ok.

Thanks!


texts:
We are looking to use the TLV320AIC3111 audio codec to process some sound data that we are receiving from MP34DT05-A microphone. We then look to transmit the data wirelessly over BLE using the BlueNRG-1 BLE Module. We've already worked on the BlueNRG-1 and have managed to transmit PDM data input over BLE. But the TLV320AIC3111 supports only I2S, Left-Justified, Right-Justified, DSP, and TDM Audio Interfaces according to the datasheet given above.

I'd like to know if anyone knows of any way to convert I2S to PDM, or maybe a similar BLE module that supports I2S input. We'd prefer the first option though as we've already got the BLE figured out.


texts: Derive Parameters for Unknown Flyback Transformer

texts: I am designing a 1.7 kV @ 6 mA flyback power supply. The issue I have is that it seems to be extremely difficult to find any type of high voltage flyback transformers for the design. I bought a cheap generic CRT flyback to experiment with, but being generic it has no datasheet to speak of. I assume I can derive the winding ratio easily enough, but what about the other parameters? For example, to figure out the optimum frequency can I just do a frequency sweep until I find the highest output voltage?


texts:
When using CAD software to draw board layouts, is there any convention on how to represent heatsinks attached to, say, some power transistors? I want to make sure they don't interfere with one another, and representing them on the board layout makes it easier to spot problems when I am moving stuff around.

It seems to me the alternatives are:

represent heatsinks as a separate component
modify the transistor's footprint so that it includes the heatsink
just draw the heatsinks on some separate layer that's normally off, and turn it on when checking for interferences

So far, I am very partial to the first option, and have been making heatsink components on Eagle and adding them right next to the transistors:

However, I've never seen anyone do it like this. Is this a bad idea? Is there any sort of convention on that?


texts: Why there are 2 definitions for high level logic input in the following datasheet?

texts:
I was referring a power sequencer datasheet at

https://www.dialog-semiconductor.com/sites/default/files/slg7nt4618_ds_r024_03102016.pdf

Iam confused with 2 definitions for the high level (circled below). Can anyone please clarify which one I have to consider?


texts: Silly question: using only the positive terminal on a battery

texts:
Right, so this is probably a pretty noob question, but I'm really interested so anyway...

Suppose I disconnected the negative terminal on my cars lead-acid battery. Instead I grounded the frame of the car to a good ground. The voltage difference is now 12V  again and my car should work, right? The current would flow from the positive terminal to ground. Would the battery still work, ie. would the chemical reaction still take place, since there is nothing connected to the negative terminal?

What if I did it the other way around and connected an outside 12V DC source to the car, but left the negative terminal connected to the car with no other ground.

I hope my question makes sense haha. I don't know enough about batteries and electrical engineering to understand what would happen


texts: I was thinking today and am curious, assuming there is an open collector output on two chips, one that runs on 3.3V and cannot tolerate 5.0V, and a 5.0V chip, could they just communicate by using pullup resistors with the correct voltage? What does a level shifter do that makes it worthwhile to buy?


texts: How to filter out in-band noise at the same level as my signal?

texts:
I'm implementing a system wherein I'm detecting waves as they come trough my piezoelectric sensors in a board. Essentially, I would want to record the time these signals appeared in my sensors as I want to localize the position of the source.

Basically, I'm waiting for sound waves to appear in my sensors after someone taps the board. and from the time difference, localize its position.

However, the board (I'm talking to a whiteboard here) can also absorb sound waves from environment and depending on the environment, these can interfere on my signals.

One of the solutions we had is to raise our threshold level. The problem we had is that our intended signals usually starts small and before rising to levels above the noise. By the time the level of the signal is above the noise, the timing that we would have wanted had already passed.

Since the noise is also sound signals, they occur at the same frequency as our intended signal.

Would there be anyway for us to filter out this kind of noise?


texts: Building my own brushless 3-phase motor driver to use with an Arduino

texts:
For educational purposes I want to build from scratch a PCB that would allow me to control an hard disk motor I scavenged from the trash. To do so, I was thinking about using AO3400 and AO3401 (PNP and NPN) MOSFETS that come in the SOT23 package (they are rated for 4.9 Amps so I thought that should be enough). I designed a simple 2-sided PCB using Fritzing:

The idea would involve the upper part to go to the three wires of the motor, the 3 bottom-left side pins should be switched between logical 1 (5V) and logical 0 (GND) by an Arduino which I protect from draining too much current with the three 1kΩ 0805 resistors. Finally the bottom GND pin should connect both to the external batteries and the Arduino's GND and the VCC should get the 12V from the battery.

Since I am no expert (I barely know anything about electronics), I want to ask someone with more experience before I risk frying my Arduino: Would this work? If not, how should I change it?

EDIT: The three blue wires going from the resistors to the gates of the MOSFETs should be on the back side of the PCB.


texts:
I am trying to add a reverse voltage protection circuit to my circuit. I searched for some circuits and simulated them with an online simulator (Circuit Simulator Applet).
It might work as I need it, but I'm not sure how it works when I invert the input voltage.


texts: How does transmission rate scale with number of of lanes in MIPI CSI2?

texts:
What I'm actually interested in is how non-MIPI data is converted to CSI2. Say I'm feeding a P-bit pixel to a CSI2 camera with n data lanes, how are the bits shared among the data lanes? If the pixel was serialized into a P-bit word, or if the pixel came in from a P-bit parallel bus (doesn't matter), does each lane simply take P/n of P bits and just transmit them (perhaps adding some overhead)? If that is the case then data rate C is scaled down proportionally to C/n.

I tried looking it up on the MIPI Alliance website itself but I couldn't find anything solid in their PHY overviews. Also I'm not sure if I'm asking about  confidential IP here.


texts: SPI flash memory doesn't work without huge delays

texts:
For my graduation work I am developing a microcontroller system where the MCU (MSP430FR5739) talks to an SPI flash (SST25VF080B to be particular). I've achieved this without using the eUSCI SPI master (by bit-banging the thing) but no matter what, the flash always returns a 0x00 byte if I don't leave gigantic 2000-cycle delays between clock pulses.

On the datasheet it says that the flash could work at up to 80 MHz, and I've clocked the MSP430 at 24 MHz, so my thought process here is that it should be working without any delays at all.

My questions would be:

The flash IC is on a daughterboard and is connected to the main
board with approximately 2 inches of 22 AWG single core wire. I know
that solid core wire is terrible for high frequency, but would
replacing these help speed it up?
If I most certainly have to have the delays, what else can I do to
speed it up?


texts: If there's no current through a battery, can it supply a voltage drop across a resistor?

texts:
simulate this circuit – Schematic created using CircuitLab

I've solved for all of the currents in the circuit (I used an equivalent resistance for the middle two resistors) and the current through the 6V battery is 0 A. If there is no current through this battery, can it supply a voltage drop across the rightmost 600 ohm resistor? In other words, in this circuit, what is the voltage drop across the rightmost 600 ohm resistor?


texts: Disabling trailer protocol when using this W5100-based Ethernet shield

texts:
I have an Arduino Duemilanove (ATmega328) and Ethernet shield (based on the WizNet W5100). My network gateway is a D-Link DSL-G604T.

Using this setup, I can contact computers on my local network fine. However, when I attempt to contact computers on the public Internet, the device times out. I traced the packets going back and forward using Wireshark and the problem appears to be that the gateway is not responding to the W5100's ARP request.

I saved the ARP packet that the W5100 is sending and the ARP packet that my computer is sending and compared them. The only thing different is that it is not a timestamp, address, length or sequence number that the W5100 is sending a trailer at the end of the Ethernet II frame.

According to RFC 1122 - Requirements for Internet Hosts - Communication Layers, section 2.3.1, a trailer may only be used if both hosts have previously agreed to use them. I suspect that my gateway is not able to handle trailers and is ignoring the packet.

Is there a way to disable trailers in the W5100?

Here are the ARP packets that are sent by a computer on my network that is able to make Internet connections and the Arduino device. I have also provided a diff of the two packets. In the case of the packet that is sent by the computer, the gateway responds, in the case of the packet sent by the Arduino, the gateway does not respond. Note that I have changed the hardware addresses, but that's all.

Computer Packet
Arduino Packet
Diff


texts: What is meant by the "one-shot" avalanche rating of a transistor?

texts:
I'm using the P-channel half of an IRF7343PbF as a high-side switch to actuate the coil of a Gigavac P115 relay.  I would like to be able to turn off the relay as quickly as possible after detecting an overcurrent fault downstream, in order to break the high-power circuit before the fuses blow.

simulate this circuit – Schematic created using CircuitLab

If I use a freewheeling diode across the relay coil as is typical to protect transistors switching inductive loads, the contacts take almost 20 ms to open - too slow.  With no diode, at turn-off the transistor avalanches with about -60V across Vds.  This lets the relay coil current fall much more quickly and the contacts open only 3 ms after the gate is commanded high.  I measured the Id and Vds waveforms and the integral of their product gives an avalanche energy around 1.6 mJ.  This is in between the MOSFET's single-pulse avalanche energy rating (114 mJ) and its repetitive avalanche energy rating (0.2 mJ).

So what do they mean by "single-pulse"?  Is it really only permitted once in the life of the device, or can you do it as often as you like provided Tj is at room temperature before each pulse?  In my application the avalanche would occur a few thousand times over the life of the system, and never more frequently than about once a minute.  The junction temperature should stay cool.  Am I risking cumulative damage to the FET by repeatedly (if infrequently) forcing it into avalanche?

FWIW I gave it 500 cycles on the bench at 1 Hz and it seems to be fine so far.  That doesn't mean I'm not abusing it though.

Of course I can avoid this issue by using a bidirectional TVS across the coil with a clamping voltage around 50V, but I'd still like to know.


texts: Doubts in using UCC27537 Gate driver to drive IPA60R120P7XKSA1 MOSFET

texts:
I want to use UCC27537 gate driver to drive IPA60R120P7XKSA1 MOSFET but I have some doubts.

To avoid voltage oscillations at the gate, do I need to include resistors in between MOSFET and gate-driver?
According to the datasheet, the gate driver can source up to 2.5A and sink 5A, so is it the current when no resistor is connected between the MOSFET and the gate-driver or we have to limit it to the given current?
in the datasheet of MOSFET, it is given that the MOSFET gate resistance is around 8 ohms, so should I connect external resistors?
If the resistor is required then a lot of power will be lost through this resistor, is there any special resistor for this? or recommend me any if you have any idea...

please help me, I do not want to burn gate-driver and also want no oscillations.