texts: Can you actually break an FPGA by programming it wrong?

texts:
Can you actually break an FPGA by programming it incorrectly?

I'm a software guy really. It's no secret that if your software is wrong, you could destroy all sorts of important data, and perhaps even crash the whole machine. But it's really difficult to physically damage a computer just by programming it.

(There are endless rumous of a Halt-And-Catch-Fire instruction, or being able to reflash the system firmware to brick the motherboard, or programming incorrect values into the graphics card to fry your monitor. But these all seem to be exactly that: rumours. And all about long-obsolete hardware. It seems really, really hard to break modern computer equipment with bad programming.)

With an FPGA, you are (at least nominally) wiring individual circuits together. It seems completely plausible that physical damage might occur in case of a mistake.

For example, you could write some VHDL requesting that two outputs get tied together. If they output different logic levels, I imagine that would probably fry something. (I would hope that your synthesis tool would scream at you to not do this... but I don't know if such tools actually implement that level of error checking.)

It also seems quite possible to accidentally pick the wrong model of FPGA in the synthesis tool, and thus ending up trying to program your chip with a bitstream intended for some totally different model. I don't know what that would do, but I suspect it would be "bad".

For that matter, you could definitely connect the FPGA chip to the rest of the circuit incorrectly. E.g., if you mess up the pin numbers, you might end up with the board trying to drive an I/O pin that the FPGA itself is also trying to drive. Do the I/O pins typically have any "protection" against such a mistake? Or will the chip just fry?


texts: Molex 5556 vs. 44476 Terminals for ATX / EPS connectors

texts:
I'm looking into terminating a custom-length power supply extension cable to make everything look nice / fit in an awkward case. While researching parts I noticed that the EPS12V v2.0 specification states that Molex 44476-1111 or equivalent contacts be used but it also says that the Baseboard Power Connector should use the Molex 39-01-2240 housing. The housing is from the 5557 Mini-Fit Jr series and it specifies that 5556-series terminals be used rather than the 44476-series that EPS12V states.

Are the 5556-series terminals roughly compatible with the 44476-series? If not, should I use 44476 since that's what is in the spec?

The dimensions of the two are similar but not exact (data sheets for the 5556-series and 44476-series). I noticed that the 5556 is tin-coated-brass whereas the 44476 are tin-coated-copper-alloy. Maybe that's the big difference?


texts: How to make a simulation for wireless power transfer circuit in HFSS (High Frequency Structural Simulator) software?

texts: I want to simulate a circuit of wireless power transfer consisting of two resonating coils along with a loop with each coil. I am stuck with introducing a coil in HFSS.


texts: Control dual color LED without microcontroller

texts:
I have a latching, SPDT switch with dual color LEDs (the first page of the datasheet), that can either be Red or Blue depending on the polarity of the voltage. I would like them to be one color when the button is in position one, and the other color when the button is in position two.

The purpose of the button is as a manual backup switch for a relay board that is normally controlled over CAT5. The relays are tripped by shorting the board's gnd to the pins of the relays.

My voltage source is 110V wall outlet being stepped down to the 12V that both the relay board and LEDs in the button want.

My pinout for the button is:

C: going to gnd of the relay board

NC: nothing connected

NO: going to the relay pins

I found this guide which I believe demonstrates the principal of what I'm trying to accomplish, but with a momentary SPST button and no extra hardware connected, and the intention to use connected to a microcontroller. I can't use a microcontroller in this project as  a) no room in the box for one  b) no money in the project budget for one.

My main concern, and reason for not just tinkering around, is that the boards are super sensitive to voltage (I already fried one by accident), and I'm worried about sending extra voltage back down the line to the relay board.

Any and all help/tips/suggestions are greatly appreciated!


texts: Expression about the output voltage Op amp BJT

texts:
Determine the expression of the following circuit:

simulate this circuit – Schematic created using CircuitLab

(A) \$Vo = \eta \cdot V_T \ln(\frac{I_{C0}R}{V_i})\$

(B) \$Vo = -I_{C0}\cdot R \left[e^{\frac{V_i}{\eta V_T}}-1\right]\$

(C) \$Vo = -I_{C0}\cdot R \left[e^{-\frac{V_i}{\eta V_T}}-1\right]\$

(D) \$Vo = - \eta \cdot V_T \ln(\frac{I_{C0}R}{V_i})\$

ANSWER C

I really find the reason why the answer C is correct. How can the output voltage goes to \$ I_{C0}R \$ when the \$Vi\$ increases?

the transistor Q1 isn't on cutoff region?

Please any explanation?

Original picture:


texts: Will this one-switch resonant topology work?

texts:
simulate this circuit – Schematic created using CircuitLab

Will this thing work? I do not mind the horrendous amount of interference this may produce. Principle of operation is:

Switch-on causes C1 to conduct some current into base of Q1.
When C1 is charged, Q2 turns off. Uce is limited by D2.
IRF840 turns on, causing L2 and C2 to resonate.
The voltage change on C1 causes Q1 and M1 to turn on and off synchronously with the resonance of L2-C2.
The voltage reverses polarity, causing D1 to not conduct for 10ms.


texts: Bluetooth signal through survival blanket

texts:
I'm about to design a system with a build in bluetooth module enclose in a box covered by a survival blanket. (little satellite model)

According to Wikipedia, the survival blanket is made of PET (mostly plastic) and a thin metallic sheet.

I'll using a HC-05 bluetooth module, since it's very cheap, I not 100% sure of it's capacity to acquire signals through the metallic sheet.

Do you think it going to work fine? Or should I build a small antenna extension outside the enclose box?

Since I have almost no knowledge about antenna design, I don't know how to build such a low cost antenna.


texts: How to linearly boost the output of a Gaussian shaping amplifier?

texts:
I have a pulse detection set up that takes in analog pulses (with relatively long tails, gamma spectroscopy). This pulse is sent into a shaping amplifier, that removes the tail, and shapes the pulse to a Gaussian, around 1 us duration. The output from this amplifier is then a pulse between 0-6V, and read out on an oscilloscope. The frequency of pulses to be detected is <0.1 MHz.
I would like to boost the output so that the 0-6V pulse is converted linearly to a 0-10V pulse. What are the options for doing linear pulse amplification?


texts: SD Card SPI Interface Issue - Read Operation Returns 0x3F/0xFF instead of 0x7F/0xFE

texts:
I have written an SPI driver for SD cards (in micropython). There was nothing available for my specific hardware (a pycom.io LoPy SoC), so I started by studying a long list of drivers, written in python and C, and the variety of approaches was staggering. Many had useless/unecessary code, "plain wrong" code, or code that might work on some cards but not others. Needless to say, the variety of different SD cards and their loose adherence to the standard does not make this an easy task.

In any case, out of the dozen or so SD cards (all microSD) I have for testing (various brands, speeds, and sizes), all but two work perfectly. Both are different brands, speeds, and sizes, but they behave (badly) in exactly the same way. Both initialize correctly, returning all the expected "meta" data, but when doing the first data read, they fail and fail consistently.

In SPI mode, reading a "sector" is started by sending a CMD17 in the normal way (same code in my driver that sends all other commands), then reading one byte at a time, waiting for a "token" that marks the start of the data (in this case, the token is 0xFE). For all of my working cards, I consistently get 0xFE as the second byte (the first byte is almost always 0x7F, but that's supposed to be irrelevant--the SD spec only cares about the first 0xFE). But on the two failing cards, I consistently get 0x3F followed by 0xFF. The code fails, because no 0xFE was ever seen. But the interesting thing here is that 0x3F/0xFF is 0x7F/0xFE shifted by one bit. That's why I feel like this is a hardware problem.

I've read just about everything I can get my hands on regarding SD over SPI. I've looked at the signals with a scope (nothing unusual to report). My circuit is powered by a high-quality bench supply and has sufficient bulk and decoupling capacitance, and has very short wires. I've also tested the two cards that fail on my PC's SD card slot, and they work as expected. Yet, the issue I describe is 100% consistent.

So the question is what to look at next? I've been at this for days, and I'm out of ideas at the moment.


texts: Class D amplifier output filter calculation

texts:
I want to build a simple amplifier with TI's TPA3116D2, which is "filterless" Class-D amplifier. This device can be run with a traditional LC filter at the output, or, if the speaker wires are short, simply a ferrite bead with a 1nF capacitor.

I'd like to test with a traditional LC filter. The example values in the datasheet are 10uH and 680nF.

I don't happen to have any 10uH coils, but I have plenty of 22uH ones. What happens if I use a larger inductance and smaller capacitance?

According to my calculations, the suggested filter has a 61KHz cutoff frequency and 3.8 ohms impedance. A filter made with 22uH and 330nF will have a 59KHz frequency but the impedance will be 8.16 ohms

What does this mean in this case? Will it affect the performance of the device?


texts: How to deal with multiple pull-up resistors on modules

texts:
I was thinking about doing a modules for a development board I did a few days ago that will include spi/i2c interfaces.

The problem is that I didn't included pull-up resistors in the MCU pins in the main board and was thinking to add them in the modules to make them more "generic" so every user could use them without need to add extra resistors in the prototype board.

But then I faced the next problem. If I add the pull-up resistos in the extra modules and I connect for example two or more modules to the same bus I'll get those resistors in parallel so the resistance will drop and will not accomplish their function.

But if I add the pull-up resistors to the main board I'll have those pins in the MCU always as active low.

So the main question is:

How to have multiple modules connected to the same bus having on each of them the pull-up resistors but not get them in parallel when you've more than one module? Is that possible?

Or the best solution here is enable the pullup resistors in the MCU and don't inlcude them in the modules?

Thanks.-


texts:
To graduate (Grade 12 or Year 12), I need to do an self-thought experiment in Physics. I decided to do something about stepper motor because I learned that they use this type of motor for robot arms.

Of course, I know that I cannot build a real entire stepper motor. However, I was wondering if i can build a much simpler one with less stator and rotor teeth.

I asked this to my physics teacher, but he isn't convinced about this idea.

My first question would be, Is it possible to make a simpler stepper motor? like this one.

If yes, I am also a bit unsure about what will be my independent and dependent variables. I planned to make the current my independent variable and measure the angle of the magnet, since by energizing multiple coil at the same time, the angle will change.

Are these variables ok for my experiment or should i choose a different one ?

Any help would be appreciated.
Thank you.

Pingu


texts:
Hi everyone,
as you can see from the picture, i have an AND logic gate. The LED has to be off when the Va is 0V and the Vb is 5V, but it turned on?????? Can you guys explain why?

Thank you.


texts: What solutions are there for getting HD video?

texts:
What solutions are there, preferably single chip solutions, for getting HD video over DVI/HDMI?

My googling is not giving me much, only about the Blackfin chip from Analog.

I know about the Propellor from Parallax and that it can give SD video out easily, and how FPGA's can do it too, but other than those three I do not know of any other single chip solutions that can give me HD video over DVI/HDMI.


texts: Faulty temperature sensor on PCB - lights keep blinking, how to replace this?

texts:
I’ve been working on a broken continuous operating high power LED system - it starts blinking when powered. This was an indication of overheating and it was clear that the cooling fans have stopped working. I tested both fans individually with a PSU and they did not respond.

I replaced the set with two new fans (same type and rating and size) and the fans work fine. But when I connect it to the PCB output that powered the fans, the overheating sensor is active and the lights start blinking. (even if it’s cold and just turned on)

I noticed that there’s a temperature sensor (attached pic) but it says nothing more than “T1C”. The sensor is extremely tiny and can be seen in the pic attached (right next to the LED)
I cannot seem to find out what exact type it was and I don’t know how to fix this issue.

The second issue would be the power output. I’m inclined to think that it will be fixed when the sensor is replaced, but I cannot seem to get a constant output of 48v to power the two fans (2x 24v axial brushless fans)

But for now, I would appreciate any help in fixing the temp sensor.

Thanks
1


texts: A question about Vce of an NPN BJT in saturation region

texts:
Below is an NPN transistor symbol and the voltages at its terminals are Vb, Vc and Ve with respect to the ground:

I read that: during the saturation the Vce = (Vc-Ve) settles to around 0.2V and the further increase in base current will not make Vce zero.

But why doesn't Vce become zero?

As far as I know: when the transistor is saturated, the base-collector junction turns on, like a diode, so the collector voltage will follow the base voltage increase, only it will be a diode-drop below. But the same thing happens between the base voltage and the emitter voltage. So at saturation and beyond one can write the following(?):

Let's call the diode drop as Vd between p and n junctions, so the collector and the  emitter voltages can be re-written in terms of the base voltage as:

Vc = Vb- Vd

Ve = Vb -Vd

Vce = Vc -Ve = 0

Where am I wrong here?


texts: No output being measured on transimpedance amplifier

texts:
I have been playing with a SFH 213 photodiode (the clear one) and I've hooked it up to a TLV2371 op amp so as to resemble an ordinary transimpedance amplifier.

I've varied the feedback resistor value from 10M-30M and still I get zero voltage from V_out. According to the data sheet for the photodiode the dark current is 1(<5)nA so I figured with 10M resistor I would get 10-50mV at the output.

I've tested other configurations with the op amp such as a non-inverting amplifier and it works just as expected. So I don't think the op amp is broken. I also hooked up 2 photodiodes (parallel) in case the one I was working with was broken and to make the signal stronger but still no output. The flat side of the diode is facing pin 2 (-in) and the round side is in pin 3 (+in) which is grounded. The +9 Vcc for the op amp is completely arbitrary value.

I feel like it's a simple issue and I feel silly for asking. However I just can't figure out what's wrong.

simulate this circuit – Schematic created using CircuitLab


texts: Relationship of the base resistor and the collector resistor in turning on / off a 12V load with 5V using a transistor

texts:
I am testing a solution to turn on / off a 12V load (the load will be MOSFET for controlling DC Motor) using 5V input with a transistor (see attached file for the schematic and the test results). My questions are:

Why the solution seems working when VCC is +5V (the measured current are 7.3mA, 4.39mA when the LED is On);
Why the solution seems working but the measured current is quite low (1.36mA) when both R1 and R2 are 10K (when VCC is +12V)


texts: Why does this driver not have a load resistor?

texts:
Im trying to drive a motor with this kind of circuit since my micro is an old 8051. The voltage I use is 5V and PowerV is also 5V.
I also have a 56 ohm 1/2 watt resistor in series with my motor because I didn't want to blow anything up.

Sadly, the motor does not start regardless of pin state.

When I measured the current (where load is supposed to connect) with the voltmeter, I get about 41mA and 0mA since my 8051 pin toggles between on and off at a slow rate.

I then replaced the PNP with the 2N2907 and measured current again and I got 43mA.

I think those numbers are so low with motors.

I also shorted the resistor between PNP collector and NPN base since I was using a load resistor.

I think someone suggested replacing the final NPN with a FET of some sorts, but If that's the ultimate solution then I need one with the same kind of pinout so I don't have to redo my entire circuit.

If I can get away with using a lower load resistor then I will just go for that.

So It makes me curious. Why in the attached design is there no indication of a load resistor? and why is there no indication that I need a 1/2+ watt resistor anywhere?

The original reference to this schematic is found at:
8051 - Can an NPN transistor be driven?


texts: Question about symbol in front of MOSFET GATE

texts:
I hope you are safety & healthy. I have a question about symbol in front of MOSFET GATE.
The circuit that Im analyzing transforms almost ~311 V filtered and rectified DC to 48V DC. As In images I saw a symbol that is in green box. It looks like inductor but there is no value on schematic. I dont know what is meaning?. And also MOSFET is enter link description here . What is this?
======================================================================
Picture about to answer : I took a photo lately about my question.  As to V.V.T's answer this is ferrite bead, yes. You can see it in MOSFET's GATE pin.


texts: How does this BJT transistor work without any connection to its base?

texts:
I came across this circuit today and I am now wondering how that transistor works without any connection to its base. See below some schematics and a few images of it.

If it works, is it safe to wire transistors like that (for the transistor and the user)?


texts: Is the regulator doing short circuit after enable?

texts:
Is it my circuit/PCB doing a short circuit after enabling the regulator? See image. (I checked the connection physically and is fine.)

I don't understand why after enabling the regulator using the line digitalWrite(4, HIGH) (Arduino IDE 1.8.9 ATMega328P), the power supply or LED or I don't know what thing happens... And the code freezes or I don't know.

digitalWrite(5, HIGH) is pwr2 label for enable the simcom gprs IC.

I'm feeding my custom PCB with FTDI board. Other sketches work fine, but when I try to enable the regulator, the FTDI LEDs have lower intensity of the brightness and the code is not executed to the next line. If I comment the line, the code follows the normal execution.

My sketch worked fine by connecting the FTDI to another laptop through USB.


texts: Do the logic gate inputs of 74HCXX integrated circuits exhibit a high impedance?

texts:
Do the inputs of the 74HC374-SMD D-type flip flop have high impedance inputs? In datasheet is stated that it has buffered inputs, I assume that means high impedance, right?

In other words, do I have to put resistors in the input pins?


texts:
I found this schematic for a simple SMPS.

I want to use it to build a 24V/2-3A power supply for a soldering station.

How are the turns on the transformer calculated?

For the primary I can use

$$N = \dfrac{V_{in} \cdot 10^ 8}{ 4 f \cdot B_{max} \cdot Ac}$$

and get like somewhere around 30 turns.

But for secondary I don't get it right. In the schematic it says 5 turns for 14.4V. I get about 1-2 turns.

$$240V \cdot \dfrac{1.4}{14.4V \cdot 0.98} \approx 23 \implies \frac{30}{23} \text{ turns} = 1.3 \text{ turns on the secondary}$$

What am I calculating wrong? Should I use a 50% duty ratio for this type of SMPS? Even then, it does not get close to 5 turns.


texts: What does it mean for the connections of this transformer to be in parallel?

texts:
Using this transformer, datasheet.

When the datasheet indicates that the windings are connected in parallel, is it referring to connecting pin 1 with 2, 11 with 12, 8 with 7, and 6 with 5?

If yes, what is the reason this flyback transformer is manufactured in this manner, rather than connecting the respective pins within the transformer?


texts: What is the most visible low power indicator?

texts:
I have an device to design on a low power budget, and I would like to have indicator LEDs on the front panel. What should I choose to be as visible as possible with the lowest possible power consumption? The instrument will be used in a typical office/lab setting.
Can do better than a green LED, with as much current as I can spare? Is there another technology I should look at?


texts:
I would like to use my audio interface to trigger a mains relay, as soon as the audio interface is turned on. Unfortunately, the interface turns on electronically, as opposed to using a mechanical switch. (I need to hold a button for 3 seconds to turn it on. Annoying but c'est la vie).
Therefore, I figured using the S/PDIF output of the audio interface to trigger the mains relay, by cascading two relays: one relay triggered by the S/PDIF output, which in turn triggers the mains relay.
So with the audio interface turned on and nothing playing, I measured the S/PDIF output on the scope and Vmin and Vmax are around -700mV and 500mV respectively, yielding appx. 1.2Vp-p and about 4mV Vac measured with an AC multimeter.
Unfortunately, I reckon 4mV is too low for triggering any kind of relay.
For raising the voltage, I looked at level shifting, but I it's problematic because as demonstrated by the Vmin/max, S/PDIF is a differential signal which makes things trickier, and besides, as far as my limited knowledge goes, I think level shifting needs a higher base voltage anyway.
Finally I thought about amplifying the S/PDIF signal with a MOSFET but I've no experience with those and I've no idea how to go about it.
I prefer to avoid something like an Arduino.


texts:
I was recently given a display which is powered by a IST3042. According to the datasheet this is a 160x2 TN/STN-LCD Driver. I need to use the SPI mode as this is the interface I have access to.

The first thing I stumbled upon was, that it uses a 9-bit data transfer which is similar to I2C but doesn't make use of the ACK/NACK signals. I tried writing to the display RAM and "something" happens but I'm not quite sure what I'm really doing. If I understand that controller correctly, I need to write the command to set the data pointer to position 0, and then start writing values. Each bit corresponds to a single segment as far as I understand but I am getting strange results depending on what I write. I think that the SPI write is ok because I get correct values on my scope (also the mode should be correct).

Now for the main question:
Does anyone know of a "similar" device where I could find an already existing driver as sample code to take a look at. I haven't really found something similar because maybe I am lacking the correct search terms.

After some search, I have found that this datasheet from the PCF8576C has some .. interesting similarities but I'm not quite there yet.


texts:
I have a digital caliper/gauge: it works with FTDI interface and digimatic (or very similar) protocol. It is connected via usb port. I can connect it correctly, and I can read it with programs like GtkTerm or similar. I can also read the instrument via stty, but only physically pressing the button on the caliper which allows to send some signal on D+ or D- line (I don't know which one exactly....).

Is there a way (in bash for example) to send a signal on the usb lines D+ D-? The electrical specifications of the instrument says that the needed signal should be a low voltage to the "request line" for some milliseconds; which is one of the tho data lines in the usb connector, I suppose....

The tools which showed to be able to read the caliper / gauge made use of commands like DTR / RTS; can stty alone send such signals to usb ports??


texts:
I have an AC adapter jack that has three terminals, L(eft), M(iddle), and R(ight). If I plug in the power supply and connect the plug to the jack, these are the readings I get from the multimeter.

L(red probe) M R(black probe) = +5V
L(black probe) M R(red probe) = -5V
L(red probe) M(black probe) R = 0V
L M(red probe) R(black probe) = 0V

So is the middle terminal ground? Or is ground the the right terminal? I heard that I only need to use two of the terminals when supplying power to components. Is this true?


texts: Will DDR2 memory work with DM pins tied to LOW, if no data masking is required?

texts:
I have a board with the LDM and UDM pins swapped.  If they are tied to low, will the memory still 'work', given that data is always written to mod 4 addresses and always using all 4 bytes?

Memory is Micron MT47H32M16HR-25E.


texts:
I am planning on using LME49990 amplifier for my Sigma Delta ADC front end. My problem is I don't have dual supply and I can provide only +5V. So Will it work with single supply.
Will there be any performance degradation with single supply.


texts: LM7805CV output voltage drop to 2.5v after connecting load

texts:
I've made a simple linear power supply for micro-controller with a transformer and LM7805CV as seen in the picture.

LM7805CV input voltage is 35V and output without load is 5V but after connecting a minimum load like an LED with 1K resistor output voltage drop to 2.5V.

I've checked regulator input voltage and it's steady without any change but regulator input-output voltage increase to 32V which I think is the main reason for dropping voltage.

Transformer = 2x24V Center Tapped


texts: Continuous current capacity of this conductor?

texts: How much current can a copper conductor that is 2 meters long, 0.003m thick, and 0.00045m wide continuously carry? Also, the resistance is about 0.02 Ohms.


texts: Geometric information within 1D streams of electrons/photons

texts: How is light—or actually any frequency in the EM spectrum—self-encoding and self-modulating 3D info in its 1D self, so that it “knows,” once it strikes a surface, to discharge all the data perfectly as a 2D image?? It’s not like FM or AM circuitry is being employed here... light is self-modulating to encode 3D scenery data perfectly without external interference to self-induce a modulation.


texts: Subharmonics frequency Vs Switching frequency

texts: In current mode control of switching power supplies, it says that the subharmonics instability equals 1/2 of the switching frequency Ws, Can you please explain this fact?


texts: measure instantaneous position of a solenoid piston?

texts:
I'm trying to improve speed & force of a solenoid and its power electronics strategy.

So far I can measure many variables such as :

tension
current
waveform shape
time to reach final excursion

How can I measure the instantaneous position of the piston while it is moving?

being able to see the signal as an analog value is a plus...

there must be a simple way... :)

(source: globalsources.com)


texts: How does this circuit in an electric mosquito swatter work?

texts:
I had an electric mosquito swatter lying around so I decided to open it up and check out how it works.
I understood some parts of the circuit however I did not clearly understand how the rest of it works.
I have posted the circuit of the mosquito swatter. (I did notice that there was a similar question on the forum but the circuitry differed and it was not yet solved.)
Here's the circuit:

Things I did not get:

Why did they use the capacitor and resistor in parallel as input for the full bridge rectifier?
Why is the battery just directly connected to the output of the full bridge rectifier.
How is the (6-pin) transformer connected internally? If I can understand this I am guessing I can understand how the transistor works.
What is the configuration at the output of the transformer?

Note:

Below the main circuit there is a diagram that shows the interconnection between the transformer pins when I used a multi-meter to check for continuity, note the transformer was still on the pcb.
The 0 and 1 at the output is just to indicate that the 0 goes to outer 2 meshes and 1 goes to inner mesh.
The LEDs are red.
Some of the components did not have values written on them like the capacitor C6 so I removed them and checked them using a component tester so the values may be slightly off the standard values.
I numbered C6 out of order sorry about that.
The resistor parallel to C1 is 675kOhm and not 675Ohm.
The resistance between Xmer pins 1-2: 2 Ohm; 3-6: 0.8 Ohm; 4-5: 245 Ohm.

Additional working note:
When the device is not charging the NO switch is closed and the push button is pressed this seems to charge the meshes for the next electric swat.


texts: How can Google Fiber make a difference since most of the mediating wires out there are copper?

texts: Optic fiber sends more data more quickly. But if you look at the Google Fiber map you will see that only the local connections are optic. The rest of the world is almost entirely copper, right? So won’t the slowest medium determine the overall rate of transmission? What good is it to speed the rate from my house to the telephone pole outside, or to a handful of switches, if these are all linked copper-wise?


texts: Inconsistent readings using Pressure / Altitude sensor (MPL3115A2)

texts:
I have two pressure sensors (MPL3115A2) with each connected to a Particle Photon, the sensors are placed next to each other at the same level.

In barometric mode, one sensor reads 95043 Pa, while the other read 95405 Pa. This translates to a difference is 362 Pa.

In altimeter mode, one sensor reads 1742 ft, while the other sensor at the same level reads 1658 ft. This translates to a difference of 84 ft.

I also observed that these differences (pressure & altitude) keep varying over time. I'd appreciate if anyone with experience on these or similar sensors could shed some light on this variance in measurement.

I am trying to use these sensors to get the altitude of the construction elevator in realtime, any suggestions on accurately measuring the elevator height would also be appreciated.


texts: How does one understand the complete functionality and implementation of open source cores?

texts:
I'm an ECE graduate, looking forward to my masters emphasizing on computer architectures. I've been recently involved in some open core development for educational purposes, and was asked to look into the working and if possible implement the IBM A2I, and A2O core on whichever platform (Linux) that suited me as an end goal to this learning path.
My concern is, when I look up any of these repositories on git, its seems quite illegible even though I have an above average understanding of verilog (but not tcl which was the preferred methodology for it's implementation on an FPGA) and its constraints, but it has less to do with my understanding of the HDL and more of the semantics and conventions involved in it, for example signal naming.
After being inundated with information, it was clear that my approach of simply trying to read the code was less than correct. I'm looking for some advice on how do I approach this. I understand that the information here might seem incomplete, but I'm not looking for a rigid solution at the moment because the problem itself is unclear.
--Manu


texts: Do PWM solar controllers increase current?

texts:
There are two kinds of solar charge controllers.

PWM does simple pulse width modulation to limit intake voltage (E.g. 18V) to that appropriate for battery charging (e.g. 14V). The only thing it considers is correct battery voltage.
MPPT controllers also "scan" the panel dynamically, varying their current draw to seek maximum watts.  This is constructive because solar panels are not linear, and don't naturally seek watt maxima. Decreasing current draw 5% may increase voltage 15%, and that's a win. This MPPT strategy can get 30-40% more power out of a panel.

What I want to know is, does the PWM naturally increase output current when it decreases output voltage, I.e. does it act like a buck converter?  Or must the excess voltage be consumed as heat in the PWM charge controller, like an LM7805?

If my Panel input is 14A @18V, is it possible for the PWM output to be 16A @14V?  Or is it impossible for amps out to exceed amps in?

I mention MPPT because folk wisdom in solar is PWM controllers act like 7805s, and you need an MPPT to get the buck conversion/current multiplication effect.  That advice sounds off.


texts: Kirchhoff current law with current source through a capacitor

texts:
I would like to ask whether I have done the KCL correctly with this particular circuit?
For the nth-loop:
    1/(j*w*C_1)*i_n = (1/(j*w*C_1)+j*w*L_1)*I_n + (1/(j*w*C_2)+j*w*L_2)*(I_n-I_n+1)
                     +(1/(j*w*C_1)+j*w*L_1)*I_n + (1/(j*w*C_2)+j*w*L_2)*(I_n-I_n+2)

Thanks


texts: High voltage limiter with discrete components

texts:
I'm designing high-voltage enclosure circuitry that engages a lock when either of two HV supplies reach 50V or greater.  Both are capable of 6kV output.  Below is what I have so far, where R7 represents the lock:

The two similar blocks form comparators against a 5V reference, and Q3 and Q6 form an AND gate.  Q9 drives the output.

I've had issues with op-amps and logic ICs burning up with previous designs, so all components are discrete.

This design works well in simulation so far, but I have only yet cranked up the sources to 60V.  In reality, a 100:1 resistive divider (10M:100k) will be used to yield a 0-60V range, or thereabouts (200:1 for 0-30V, perhaps).

The issue is that, at 50V, the voltage at the comparator input is too low to overcome Q1's or Q4's \$V_{be}\$.  I thought about adding a common-emitter amp with a gain of 10 at the inputs that just saturate a bit above this 50V mark, but that would also require another inverting amp following it.

Is there a simple way to go about this that I'm not thinking of?  Or is a change in configuration needed?


texts: What's the need for conductive bridges between the regions of a smart card contact pad?

texts:
Here's a scan of a "chip-and-pin" Visa Electron contact pad

It looks like a metal plate divided into regions by narrow cuts. Look for example at regions marked A and B - there's a cut between them but it only separates them partially and there's a narrow metal bridge left on the top of the cut.

That looks strange. If the regions have to be connected why not just omit the cut entirely and have one single region?

Maybe it's for cleaning contacts of the reader - as they pass over the cuts the dirt if any gets scrapped of them, but I'm not sure.

What's the reason for this design? Why are the regions partially separated by a cut yet there's a conductive bridge left between them?


texts: How to trace down why LTSpice simulation is slow?

texts:
I have a pretty complicated schematic in LTSpice (at least it is the most complicated schematic I ever tried to simulate in LTSpice).

For some reason simulation of just 20 ms turns into about 15 seconds to accomplish.

I have several theories:

The schematic is complicated, computer is slow (it is really not very powerful) so I can not expect anything faster.
I have some trouble in the schematic cosing LTSpice to short the iterations and therefore - slowdown the simulation process.

If I'd skip the first, how can I trace down the problem part of the schematic?

I tried:

cut some suspicious parts of the schematic to define if the simulation became reasonably fast (did not help - simulation time vary from something 10 to 20 seconds)
put initial conditions to "charge" capacitors to intended voltages (it helped as I could make the simulation time shorter: 20 ms instead of 100-200 ms)
I defined Maximum Timestep as 1 us:

I put 10 MOhms resistors between optos and ground

Is there any method to find a problem node?

I think that I will not ask the community to find the problem for me as I'd better learn to do it myself. So this is why I did not put my schematic in the question.


texts:
Hi all
I recently moved from Mexico to Portugal and brought some electronics I suspect they are multi voltage and multi frequency.
But reading the label of a Sony TV I got into doubt if it is or not multi village/frequency.
Attached a photo of the label. Can I plug this TV straight on power outlet?
My doubt is because in the center of the label says Energy Performance Verified 127v 60hz.
Thank you for any advice,

Hope it also applies for my Sharp one. Does it?
Thanks again


texts: Why are resistors, instead of PWM, used to control the speed of automotive blower motors?

texts:
Blower motor resistors are used to reduce the speed of automotive blower motors.

But they get hot, can burn out, are inefficient. This answer lists the benefits of PWM, yet there hardly seem any benefits of resistive speed control.

Why don't car manufacturers use PWM instead?


texts: Looking for a very precise tx/rx circuit module to calculate distance

texts:
Thanks for helping. I'm looking for a system that will help me find exact distance between a transmitter and receiver at a frequency of milli seconds, in distance accuracy of milli meters.

I want to avoid environmental factors, reflections or line of sight issues. My initial idea is to have a transmitter pulsating at 30 msec. Use the time taken between signals received to calculate the exact distance. Initially I am looking for a range of 20 m. But in future I would like to explore the idea of upto 1000m.

I think GPS wouldn't work, I am open to any modulation techniques. Are there any pre existing modules?


texts: Can anyone suggest a voltmeter that can do the job?

texts:
I am trying to make a high voltage measurement on an industrial sputtering machine.  The voltages are in the 50V to 1000V range.  Right now, we're using a Fluke DMM because we need a true floating voltage measurement (there's a lot of random common-mode noise that can't be eliminated).  It works great, but it is battery powered and doesn't have any computer output capability.

We'd really like to replicate this function with a powered meter that can talk to a computer, so the data can be automatically logged.  I've read a lot about this (although I still understand little).  I understand that, in order to get a good floating, differential measurement, the meter must be well electrically isolated from our chassis with all the common mode noise and also from its own power signal.

If I could find something that could make this measurement and scale it to, say, a 0-10V output, I would be enthralled.  Any suggestions or educations would be appreciated!


texts: How can I set up a transmission line in ADS?

texts:
I'm in the palette section with TLines-Ideal. I'm confused about what all these options mean, for example "terminal transmission line" Where is the part for me to draw the transmission line and specify a characteristic impedance, phase constant, etc.

If you can point me to some sources, that'd be great. I couldn't find much about transmission lines on ADS online and everything else was confusing to me.


texts:
Hello I am a college student working on photon counting circuit using Silicon Photomultiplier(SiPM).
Stage 0: Signal from SiPM

Description: This is an image captured from oscilloscope with the time resolution between the data points being 25 ns. If the SiPM is exposed to ambient light, the voltage goes up to -3V, which I want to be safe about.
Stage 1: Amplifier
Description: I want to invert the voltage so that the comparator will receive only positive voltage range.
Question 1: At this "relatively" high speed, is an opamp circuit a good option? Or will voltage regulator integrated circuit (ic) do the job?
Stage 2: Comparator
Description: I am trying to output 0 or 5V by comparing the input from the amplifier to a threshold voltage of 4 mV.
Attempt 1: I purchased a MAX997 and tried to compare a sinewave of 100mV amplitude, 1kHz frequency, on a breadboard with bypass capacitor of 0.1 microF, but did not show any kind of square wave I expected.
Question 2: Will comparator ic MAX997 or AD8611 be an overkill for this application (i.e too short of a propagation delay, therefore too much sampling)? if not, what kind of circuit should go around the ic to make sure I get the desired output at this relatively high frequency (bypass capacitor, resistors...etc, specific type of capacitor I need to purchase)?
Stage 3: Counter
Description: I am trying to use a 12 bit counter ic such as SN74LV4040A to count the number of pulses generated by the comparator and within an adjustable amount of time window (1 ms), I want to capture that number and send it via bluetooth to different devices.
Question 3: Can I just put the output from the comparator straight into the clock input of the aforementioned asynchronous counter? Is asynchronous counter a good choice for this application?
Question 4: Is Arduino mega a good choice for a microcontroller that will be able to transfer the count data via bluetooth (will speed be an obstacle)?

Thank you for reading thus far and I appreciate any kind of response to this question. If I have a horribly wrong understanding of this topic, please let me know. I have a lot to learn. A LOT.

Edit01
I believe this was too big of a question, so I want to start off with comparator. I currently have MAX997, but I fried one by connecting the shutdown pin to the ground. I thought I was following the correct procedure according to the datasheet, but something went wrong.

Can Anyone point out my mistake, if all I had was a pull up resistor of 1k at the output of the comparator, and rest was just connected to function generator and power supply?

Also I found a paper quite similar to what I am trying to do: link

Edit02
Below is the schematic I could draw to the best of my ability:


texts: Altium pad features and difference between Hole Size and "X-size and Y-size under Size and Shape"

texts: Could someone please explain what the green bit in the center is and what the silver ring on the outside represents? I'm trying to create a hole of a certain size and just want to know the difference between 'Hole Size' and "X-size and Y-size under Size and Shape".


texts: Why do we need NMOS transistors for NAND gate?

texts:
I have a hard time understanding how gates are built from CMOS transistors. For example, I don't understand why do we need the NMOS transistors if the PMOS transistors will already produce the desired outputs?
if X or Y on both PMOS transistors is 0 , then both transistors will be open and the output will be 0 because there will be no flow of the current
if one of the inputs X or Y will be 1 , then one of the switches will be open and there will be current flow, so the output will be 1.
it is only when both X and Y are 1 the current wont flow.
so, why do I need the NMOS transistors at the bottom then???


texts: What is the difference between "opamp" and "comparator"?

texts: In electronic part seller websites, I see that there are two separate categories for opamps and comparators. As far as I know, an opamp itself is already a comparator if you don't connect a negative feed back and run it in the open loop mode. So, what are these "comparators" exactly? What makes them different than ordinary opamps? When should I prefer a comparator over an opamp?


texts:
I am using ATMega164PA as the microcontroller running at 8MHz on 3V coin battery (current battery voltage 2.5V). I am trying to turn on tiny coin vibration motor rated 3V, 90mA using ZXMN10A07FTA N-type MOSFET.

Now that the battery voltage is at 2.5V and the vibration motor wouldn't turn on. I noticed that the gate of the MOSFET is at 2.5V which is good but the drain of the mosfet is also at 2.5V (shouldn't the drain be pulled to ground when mosfet is turned on?). There are no soldering faults, the components are at the right place. I have uploaded my schematic and the pins the gate of the mosfets are connected to.

Does anyone see any fault with the design or any suggestions?


texts:
I am working with Omron Pressure sensor D6F-PH .
When i try to read the pressure value i am unable to get a stable value.
I tried averaging but even that doesn't help.
Could somebody suggest me a trick/ techniques to help in my situation.


texts: dsPIC33E comparator interrupt doesn't occur

texts:
I'm currently trying to get the comparator on dsPIC33EP256GP502 works, but get stuck in the comparator interrupt. Basically what i want to do is just using the comparator to compare two external voltage inputs, and generate the interrupt upon the low-to-high transition of the comparator output is detect, but the program has never enter the ISR in the test.

i have tried to manually set the interrupt flag(IFS1bits.CMIF) to 1 in the main loop, then the interrupt has been successfully triggered, and entered the ISR, and in the ISR i have tested, the below interrupt condition is fulfilled:

CMSTATbits.C1EVT = 1 and CMSTATbits.C1OUT = 1

I just don't know why the interrupt cannot be triggered automatically when the preconditions are fulfilled, maybe there are some setting errors ?

I really need suggestions and instruction as i have already wasted so much time on this issue.

Any suggestions are greatly appreciated, and thanks in advance.

I paste my code for setting the comparator below:

   // comparator 1 input pin set
    ANSELBbits.ANSB2 = 1; // C1IN1+ ANALOG
    TRISBbits.TRISB2 = 1; // C1IN1+ INPUT
    ANSELBbits.ANSB3 = 1; // C1IN1- ANALOG
    TRISBbits.TRISB3 = 1; // C1IN1- INPUT

    // COMPARATOR 1
    CM1CONbits.COE = 0;         // comparator output is internal only
    CM1CONbits.CPOL = 1;        // comparator output is inverted
    CM1CONbits.OPMODE = 0;      // Op Amp is disabled
    CM1CONbits.CEVT = 0;        // clear comparator event bit
    CM1CONbits.COUT = 0;        // initially the Vin+ > Vin-
    CM1CONbits.EVPOL = 0b01;    // interrupt is generated only on low-to-high transition of the comparator output
    CM1CONbits.CREF = 0;        // VIN+ input connects to C1IN1+
    CM1CONbits.CCH = 0b00;      // select VIN- input connects to C1IN1-
    CM1CONbits.CON = 1;         // enable comparator 1

    CM1FLTRbits.CFLTREN = 0;    // disablt the digital filter

    CMSTATbits.PSIDL = 0; // continues operation of all comparators in idle mode

    IPC4bits.CMIP = 4; // set interrupt priority to 4
    IFS1bits.CMIF = 0; // clear the intrrupt flag
    IEC1bits.CMIE = 1; // Enable the interrupt
    INTCON2bits.GIE = 1 // Enable the global interrupt

// ISR
void __attribute__((interrupt,no_auto_psv)) _CM1Interrupt(void)
{
    IFS1bits.CMIF = 0;

    // IF INTERRUPT FROM CM1
    if(CMSTATbits.C1EVT && CMSTATbits.C1OUT)
    {
        CM1CONbits.CEVT = 0;
        CM1CONbits.COUT = 0;

        // Turn off the valve1 PWM output
        set_valve_channel_one_pwm_off();
    }
}


texts: Mutual inductance vs coupling coefficient

texts:
Question regarding this and this question about mutual inductance and coupling coefficient.

I'm trying to analyse a two coil system:

It consists of two coils like in the picture with 2 cm air gap between them.

I want to find out the mutual inductance and the coupling coefficient.
I'm confused, because, from my understanding, to calculate the mutual inductance, we need to know the coupling coefficient:

But to calculate the coupling coefficient, we need to know the mutual inductance.

Experimentaly, how should I measure coupling coefficient and mutual inductance between these two planar coils?


texts: A few questions about vias and pads on a PCB

texts:
I have been used to work with 1 layer PCB's and prototype boards. On the bottom layer are all the routes and the soldering , on the "top" layer are only the components.

Now, I am trying to work with a 2 layers PCB and I am confused. I created routes on the top layer and on the bottom layer.
My first question is about the utility of 2 layers PCB, is it to avoid using jump wires?
I also would like to know if you can still solder a component on the bottom layer even if the route is on the top layer? Are the layers linked somehow like vias thanks to the pads?

Here is my board on Eagle:

My questions are for the "blue" routes. For example, the ones connected to the IC4017: should I solder on the top or bottom?

I used a ground plane on the bottom layer and the power supply plane on the top layer, is it a good idea?

I am sorry if this sounds stupid, but I have difficulties to understand the "2 layers" concept.


texts: Level of a water tank with a microcontroller

texts: How do i measure the level of a water tank with a microcontroller?


texts: Transistor saturates no matter the size of base resistor

texts:
Problem

I have a circuit as depicted below, and after calculating the base resistor, I wanted to see when the base current would be too little to saturate the transistor. I kept increasing the resistance but even at \$560k\$ where the resistor had decreased the current to \$7.8\mu A\$, the transistor is still saturating. Shouldn't there be a base current threshold?

What I am trying

What I would like to be able to to, is to switch on and off a diode from an arduino pin. The supply voltage is 5 volts, the forward voltage drop across the diode is 3.4V and the transistor is a 2N3904.

According to this blog post, I should be able to find the base current by

$$ I_B = \frac{I_C}{h_{FE}} = \frac{20mA}{100} = 0.2 mA$$
with min \$h_{FE} = 100\$ from the datasheet

And then the base resistor value by

$$ R_B = \frac{V_{port}-V_{BE}}{I_B} = \frac{4.2V-0.7V}{0.2mA} = 17.5k \Omega $$

But the size of this resistor value seems to be irrelevant.

simulate this circuit – Schematic created using CircuitLab


texts:
Arduino.cc recommends this page as an introduction to XBee radios.

Physical Computing at ITP | Tutorials / Xbee Basics

  You generally choose to work in either API mode and AT mode and can't use both at the same time. However the exception is that even radios running in AT mode will still produce API-formatted packets when they receive I/O information from other radios set up as standalone sensors.

It is not very clear to me what they mean by the alternative to AT mode "API mode". What is that?

I know what a packet is and I know how different protocols have different packet formats, but what is meant by "API-formatted packet"?


texts: What is the material on top of the chips in this logic board, and should I leave them?

texts:
This is a very beginner-ish question.  I didn't know where else to ask, or even what terms to search for, so I hope this is the right place.

I'm replacing the logic board on a monitor.

The replacement board came with this gray material covering all the delicate parts (see image; one has the position skewed on purpose).

What is it?  Was it for protection in packaging, or is it a heat conducting material?

Should I leave them all, or remove a few?

It's clear that a couple were left on the original board, but not as many as came attached to the replacement.

Thanks!


texts: What is better for precision? Stepper motor VS DC Motor

texts: I want to build a steer-by-wire system and I was wondering what is better for precision a stepper motor or a DC Motor to control the wheels of the car. I tend to want to use DC and make it a Servo in order to make it more precisise.


texts:
I saw this example and I got confused.

The example shows: \$V_{C}(s)=\dfrac{R\parallel\frac{1}{sC}}{sL+R\parallel\frac{1}{sC}}V_{in}(s)\$ .

Isn't it enough to express \$V_{C}(s)\$ with the voltage drop in the resistor since it should have the same voltage too (\$V_{R}(s)=V_{C}(s)\$), or is there something with Laplace that makes it different?
Wouldn't it be the same in this case:

\$V_{C}(s)=\dfrac{R}{sL+R}\cdot V_{in}(s)\$?

Thank you in advance.


texts: Voltage divider equation except for capacitors?

texts:
Is there an easy way to find \$v_{out}\$with a handy voltage divider equation but for capacitors? If so, can you help me derive it?

I want to use it on this circuit:


texts: Proper use of open collector to switch an output

texts:
I'm working with a pre-existing piece of consumer hardware that has an open collector GPIO output, as shown below:

The Open Collector is able to source up to 100 mA.

I'd like to switch a relay (a SRD type Sanyo relay with +, Signal, and -; like this https://www.velleman.eu/products/view/?id=435570), with a simple circuit like this:

(apologies for image error, I'm using the 5VDC that the relay is rated for as the power)

And I'm rather surprised to see that it doesn't work!  I thought adding a pull-up resistor would allow me to switch the RelayInput node to +5V or 0V by switching the GPIO on and off. I'm finding that the voltage at that node stays constant (~1.8 V) regardless of what I do with the GPIO.  I'm much more used to working with Open Drain / MOSFETs and digital logic, so I think I'm missing a crucial insight here based on transistors and how the logic will be current-driven.

I've tried swapping the pull-up resistor to lower values (1k and 4.7k) and the behavior is exactly the same.

Can someone help me understand what the issue is here?

thank you!


texts:
On my quest to better understand how computers work at a deep level I have come to the question of why, exactly, silicon is used in microchips. I always assumed, naively, that silicon had a very high electrical resistance and so it made a good material to sandwich other materials with low electrical resistance (i.e. gold) in. And that this was the way that microchips were made.

After actually doing some research I see that I was wrong and that silicon is a 'semiconductor'. To keep this short I'll just skip forward and just say that I don't understand what a semiconductor is and why it's good for making microchips. I've seen several explanations and they either confused me, or the explanations completely contradicted each other, but the basic gist is that a semiconductor is somewhere in-between a conductor and an insulator. Why is that useful for making integrated circuits?


texts: Simplest phase-shifted gate drive for two mosfets

texts:
I have two inverters, driven by two IRF530 mosfets. I need to drive them with a specific phase shift. What is the simplest, most basic way to do it, for simple prototyping? (I am neglecting PWM modulation for first prototype, I just want to make circuit work)

I am currently trying with LM5046, but it seems too time-consuming for initial version. Size of circuit doesn't matter.


texts:
Sorry for the very open question, but I really know nothing about EE.

I am an Android developer,

I have been asked to create an Android application to update the firmware of a STM32 microcontroller.

Please can somebody give me some hints of how to go about it?


texts: How to simulate a component hspice model in multisim

texts:
I'm trying to simulate TS5A22364 and they have hspice and ibis models, and CAD model .bxl in Multisim. Is it possible?

I have tried to add the package model but I don't know how to add the .bxl model to Multisim, and the hspice model can't be inserted in the component wizard spice model. Is there any chance I can use this model in my simulation? If it is not possible, what simulator can I use that makes it possible? Thanks


texts:
I just came into possession of a bunch of vintage "audio" gear from the nuclear labs at Los Alamos (a bunch of test oscillators, oscilloscopes, pulse generators, etc). Been checking it out, seeing what works, etc.

A lot of the stuff has a weird AC input that looks like the picture below. Any idea what this connector type is called, and where I might be able to find an adapter to a modern plug?


texts:
These are two ends of the same cable:

The cable comes from an old headphone set and I want to re-purpose it.

What are those copper looking wire strands? I could not get connectivity between them and the 3.5mm plug. There is no conductivity even if I place the probes on the same length a short distance apart.

How do I solder the wires to a new connector?


texts: I am planning for a project I want to make that involves a custom pcb. The board is fairly simple. It has a 4 bit input. But I need to do advanced calculations from my computer to determine what the inputs would be. What is the best way to command from a java program to a 4 bit circuit board. I imagine some sort of USB adapter but I really don’t know.


texts:
I am new to microcontrollers (not electronics) and build a Shrimp except using CP2102 I am using a FT232RL UART. I am not using DTR connection for auto-reset, because it is not connected on my cable.

My circuit itself works fine. Using an ISP-Programmer (AVR Dragon) with AVR Studio 6 it is possible to flash any code. With this setup I flashed optiboot-bootloader onto my ATmega328P. It looks like it is working correctly, because after pressing RESET a LED connected to D13 (PB5) flashes three times.

Sadly, when using Arduino IDE trying to upload the "Blink"-Sketch, I get the following error:

Binary sketch size: 1.084 bytes (of a 32.256 byte maximum)
/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/avrdude -C/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf -v -v -v -v -patmega328p -carduino -P/dev/tty.usbserial-A4VXM4PQ -b115200 -D -Uflash:w:/var/folders/yp/trpfnkdn75zfzpl33tyw0tpm0000gn/T/build3725234357197838286.tmp/Blink.cpp.hex:i

avrdude: Version 5.11, compiled on Sep  2 2011 at 18:52:52
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2009 Joerg Wunsch

         System wide configuration file is "/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf"
         User configuration file is "/Users/user/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/tty.usbserial-A4VXM4PQ
         Using Programmer              : arduino
         Overriding Baud Rate          : 115200
avrdude: Send: 0 [30]   [20]
avrdude: Send: 0 [30]   [20]
avrdude: Send: 0 [30]   [20]
avrdude: ser_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding

avrdude done.  Thank you.

Searching the internet for hours all I can find is "check your wires" or "maybe bad bootloader or chip broken". I can say the chip is not broken because it works with AVR Studio and I do not think the bootloader is broken. I downloaded the latest version from code.google and also tried the .hex delivered with Arduino IDE. My wiring is quite simple just connected GND, Rx and Tx of FT232RL like the Shrimp schematic states. Checked everything multiple times and asked an engineering friend (but he is not familiar with Arduino in detail) to check it too… We both found no wiring error.

I also tried different timings from -10 to +10 seconds in relation to pressing RESET, but that did not fix anything. Also my USB-to-Serial cable is tested and working with different devices (RasPI, Cisco Router and other devices). In Arduino IDE the corresponding tty-device is selected. Board setting is set to "Uno".

What can I do to finally get my sketches onto my chip with serial and fix this problem to end my odyssey?


texts: How can I find the transfer function of a quadcopter's motor?

texts:
I want a model of a quadcopter and, thus, I need the transfer function of the motor.

Any suggestions on how to do it will be very helpful for me. Thanks.


texts: Transistor fingering reducing gate resistance

texts:
In the transistor fingering diagram (b) below, shouldn't the two transistor fingers be connected at the right side as well in order for the fingers to actually appear in parallel? As it is right now it seems clear that each finger individually has half the distributed gate resistance that a non-fingered transistor would, but I don't see how they appear in parallel if they aren't connected at the right side so the gate fingers are just dangling.
(Diagram is from page 232 of Razavi.)


texts:
Compact electronics such as notebook computers often rely on active cooling with heat pipes. Looking into a Fujitsu Lifebook right now that has its cooler running on "all engines full ahead" even at close to zero CPU load I was wondering what could be wrong with cooling before replacing the cooling unit. Dust is not an issue and the heat transfer paste has been replaced currently - not that it changed much.

So my question would be: Is there any plausible and reasonably probable failure or degradation mechanism of heat pipes that would go unnoticed?


texts:
I am a software developer, sorry if my question may sound dumb.

I want to make my home smart by controlling lights through a centralized smart home web page. So rather than buying ready-made wireless unit I want to make it by myself (it will be a fun and satisfying).

A centralized Web page will contain buttons for lights in my hall/kitten/bedroom. So while search for this I come know about ESP8266 wifi module which works on STA mode. Also, I may need a relay which will take signal from wifi module and on/off the light but as I am a novice in this I have some questions:

Which ESP module need to be selected? there are two variants I see on net one is NodeMcu and another is ESP-01, which one I should go with?
If I want to control 2 lights from a light switch panel, then is it possible control it by using 1 wifi module and 2 channel relay module or I have to buy 2 wifi module (no. of lights in a panel = no. wifi module) one for each light?
Both relay and wifi module works on 5v, What should I use to pull 5v from the 250v power supplier? On net I've seen switching power supplys but these are all bulky and contain transformers. I was hoping that there was a smaller solution.


texts: It is written in my adapter 5V at 3A and 9V at 3A and so on. How is it detected if it is 5V or 9V?

texts:
For example:
If I plug a type-C power delivery (100W maximum) into a port that can provide 100W, and then connect the lightning connector into my Iphone 6 Plus. What will be the watts entering the phone? How does it detect the volts 5V,9V,12V,15V and 20V?


texts: How do resistors limit current for an LED?

texts:
If I have an LED with Vf = 2.1V and I = 20mA, Ohm's Law says I should have a resistor in series at a value of R = 145Ω, if the voltage supply is Vs = 5V.

However, I believe can put a higher valued resistor instead, to reduce the power consumption and brightness of the LED. I've done this in experiment lots of times, but I don't know the math behind it. Does a higher valued resistor in series reduce the current going to the LED? If so, what are the equations so I can design a proper circuit without having to experiment?

Thank you for the help! I am also interested in higher valued resistors because I know they won't get as warm or use as much power.


texts: Best way of making a battery powered USB charger?

texts:
I recently made a USB charger that takes a 9V battery. I've noticed it doesn't work with a lot of devices though. It was very simple though, just a 5volt regulator hooked to a USB plug and 9V battery and a switch.

Note: I'm wanting to use what I have on hand(all sorts of capacitors, resistors, and 5v regulators) so the minty boost is out of the question(requires some components I don't have any of, such as inductors)

So what did I do wrong? I just shorted together the data+/- pins(bad idea now that I've thought about it). Should I have these hooked to something or just left unhooked? Also, should I worry about installing a 500mA PTC fuse? And lastly do I need any kind of capacitors to handle any rippling and such?


texts: What is the role of R1/C1, R3 in this slicer circuit?

texts:
I found the following data slicer circuit:

simulate this circuit – Schematic created using CircuitLab
The input is a simple NRZ (PAM-2) signal between "Vhigh" and "Vlow" (=around 0V) where each bit has a length "Tbit".
Due to bandwidth limitation, the input is also not a perfect square pulse but can be modeled as being filtered with a simple first-order lowpass with cutoff "fc".
I can't wrap my head around why exactly the author or this circuit came up with the idea of adding R1+C1 (and R3). I cannot find a single where adding R1+C1 would not make things worse (after all, it's a highpass/differentiator). Similarly, I neigher see the purpose for R3, nore can I find a case where it would be helpful.
In LTspice, the circuit works best if I kick out R1,C1 and R3 and make R2*C3 = 5/Tbit (as suggested in https://www.maximintegrated.com/en/design/technical-documents/app-notes/3/3671.html).
But I don't want to remove just just because I don't understand it...
EDIT: Maybe this was a "hard" question so I changed it to merely understand what this thing is doing...


texts: does this ensure i am reading from the ram?

texts:
I at the moment trying to reverse engineer something i made a long time ago but never understood why it is running so slowly.

I have a Zybo board, with an Zynq 7010s chip ons which has dual cortex-A9 processor and a FPGA tightly compacted together.

On the CPU side i made a game, which for each iteration generate an array of decsribing the pixel value of the game image.

=> first question => this array is pretty large, and i am bit unsure where this variable would be stored?.. I just created a variable that had this value.

Next the game image had to be displayed on vga port, for which i how to transfer the data from the PS to PL side. I used the AXI DMA, and transfered it like this:

void send_data(char c_map, u32 target){
    //xil_printf("\r\nStarting sending data\r\n");

    /* Initialize the XAxiDma device.
     */
    CfgPtr = XAxiDma_LookupConfig(DMA_DEV_ID);
    if (!CfgPtr) {
        xil_printf("No config found for %d\r\n", DMA_DEV_ID);
        //return XST_FAILURE;
    }

    Status = XAxiDma_CfgInitialize(&AxiDma, CfgPtr);
    if (Status != XST_SUCCESS) {
        xil_printf("Initialization failed %d\r\n", Status);
        //return XST_FAILURE;
    }

    if(XAxiDma_HasSg(&AxiDma)){
        xil_printf("Device configured as SG mode \r\n");
        //return XST_FAILURE;
    }

    //Value = 0b11110000000000000000000101000000;

    if(c_map == WALL){
        //bbbbggggrrrr
        Value = 0b11111111111100000000000000000000;
        //Value = 0b00000100000000000000000000000000;
        Value = Value + target;
    }else if(c_map == BALL){
        //Value = 0b10000000000000000000000000000000;
        Value = 0b00000000111100000000000000000000;
        Value = Value + target;
    }else{
        Value = 0b00000000000000000000000000000000;
        Value = Value + target;
    }

    for(Index = 0; Index < MAX_PKT_LEN; Index ++) {
        TxBufferPtr[Index] = Value;
    }

    Xil_DCacheFlushRange((UINTPTR)TxBufferPtr, MAX_PKT_LEN);

    Status = XAxiDma_SimpleTransfer(&AxiDma,(UINTPTR) TxBufferPtr,
            MAX_PKT_LEN, XAXIDMA_DMA_TO_DEVICE);

    if (Status != XST_SUCCESS) {
        xil_printf("No XST_SUCCESS \r\n");
        //return XST_FAILURE;
    }

    while (XAxiDma_Busy(&AxiDma,XAXIDMA_DMA_TO_DEVICE)) {} //wait
}

In the PL i create a block ram as such

type RAM is array (0 to ADDR_WIDTH+1) of std_logic_vector (DATA_WIDTH-1 downto 0);
signal mem : RAM := (others => (others => '1'));

Which supposedly should be a block ram, and then inside my VGA driver fill in my memeory block with the data received as input from the zynq as such.

MEM_READ:
process(clk)
begin
   if (rising_edge(clk)) then
        if ((hSyncCounter > hBackPorch) and (hSyncCounter <= hBackPorch+hDataLen)) then
            mem(conv_integer(data(19 downto 0))) <= data(31 downto 20);--"111100000000";
       end if;
   end if;
end process;

Data being an input signal.
31 downto 20 consist of the RGB value of the pixel.
and 19 downto 0 is the adress of i gave from the C.

19 downto 0 is just the grid position in the image and not a specific ram location or something like that, but where is the mem I create in the PL stored, or made of? Is it just a big giant mux?


texts: What current rating does my kickback diode need to have?

texts:
This seems like it should have been asked before, but I can't find anything. I've got a large 12v DC motor (11A startup surge, 7a running current) that I'm PWM-ing at ~20khz through a mosfet.

I, naturally, need a flyback diode to keep the highly inductive motor from doing naughty things with my mosfet.

Up to now, I've been using the CDBA540-HF (5A) as my kickback snubber, and I've never had any problems with it.

I've heard that you should match your motor's max operating current with the diode current. However, this diode has a peak current of 125A. Does this mean it can handle my motor easily?


texts:
I've used several KE 4-211-2 Sennheiser microphones to assemble a device for acoustic signal analysis. They are connected to a National Instruments data acquisition device with ~1 m long cable and sampling rate is set to 50kHz.

I've added a resistor and a capacitor as described here  (2nd page). However after a start of data collection instead of clear acoustic signal I get strong disturbance looking like a step function in low pass filter. It obviously distorts my frequency spectrum.

After investigation I found out that when NI device is not collecting data, capacitors charge slowly and start of collection probably results in dramatic drop of impedance on inputs. What might be a reason for this behavior and what should I do to make it work properly?

I think there is everything on this picture


texts:
I was looking at this StackExchange question:

Why does this rising edge detector using a capacitor and a resistor work?

I ran the simulation and I'm confused by the behavior.  On the rising edge of the clock the left side of the capacitor charges to a positive voltage.  Shouldn't the right side be negative, since current is flowing out of that side?

And then a side question: I set up the circuit on a breadboard and ran it, with a clamping diode, and did not get a suppression of the negative spike.  In fact, I get the same behavior with or without the diode.


texts: Voltage drop problem. Transistor, optoisolator, relay for programmable Christmas lights?

texts:
I'm trying to create programmable Christmas lights - a very simple circuit controlled via Arduino or NodeMCU. My problem isn't on the microcontroller side, but the basic electronics.
Now... I have 2 sets of 50 LED lights that use 3 V and draw 0.23 W meaning about 77 mA, which is significantly more than Arduino or NodeMCU can handle from a single pin. This doesn't really come as a surprise, so I need some kind of a transistor, relay or optoisolator to drive it.
I have a bunch of 2N2222A transistors that I tried to use, but running 3 V from the lights' original battery pack to the collector and connecting the lights to the emitter and running 3 V to the base (or less using a resistor - didn't check for the ohms of the resistor as the results didn't change from the direct 3 V current) I did get lights on, but due to the voltage drop involved in the transistor, they were markedly dimmed. I didn't measure the exact drop at this stage yet.
I had a 4-channel optoisolator on hand as well (HW-3999) that I decided to try as well, but it had the same results. This time I measured the voltage drop and it was around 0.6 V. Not surprising really, since the optoisolator (as I understand them) is basically a light-controlled MOSFET.
So I would like to know what are my options here? Either use a relay as a switch or should I use 5 V as the base voltage and calculate the voltage drop involved in the optoisolator and/or transistor and then calculate a fitting resistor to use in order to drop the total voltage to around 3 V that the lights can handle, or should I just use a relay?
Thanks!


texts:
I have been gifted about 2/3 of a reel (2000-ish) of these SOT-23 parts but I cannot locate any data for them.  Can anyone point me in the right direction.

Through the various datasheet sites I have determined that they are probably an N channel JFet that was obsoleted in 2007.  The local dealer in siliconix products was unable (or unwilling) to help.

the label on the reel reads:

        SILICONIX
17856             SSTC34-T1
G45004  (E10)     E9612
QA D/C Q9613E     QTY 3000
PHILIPPINES       30 MAR 96

The case marking on these is C34


texts: Why is it not possible to find pnp bipolar and n channel mosfet transistor arrays in IC package?

texts:
I use a lot of 2N3906 pnp bipolar transistors and 2N7002 n channel mosfets on my pcb. I was suprised to see that there are no cheap and commonly available IC packages for these common transistors as arrays. I have a special configuration so that the microcontroller's output switch to a negative rail. Because of that reason i can not change the type of the transistors to npn type where common and cheap packages exists (ex. uln2003)

Example :


texts: Indicator LED directly to AC mains. Which method would you use?

texts:
Some EE would do it like this, or another variant here using a capacitor and a resistor in serie with the led and a diode in parallel with the led (see links).

But what's the advantage (or disadvantage) over simply joining a resistor and a diode in serie with the led (see schematic below)?
(R1 value calculated for 380 VAC. LED 20mA, 2V)

simulate this circuit – Schematic created using CircuitLab

After reading the first comment, I designed this variant: Would the diode in serie with the LED (instead of being in reverse parallel) save energy during the unused half cycle?

The Cap has an impedance of 15K. Does the calculation of power loss and heat apply in the same way as with a 15K resistor?

simulate this circuit


texts: what is the need of the upper wheels in the figure shown?


texts: 2D convolution on 32x32 grayscale image on FPGA using verilog for inference of CNN

texts:
Hi I am new to the world of convolutional neural networks and would like to implement a 2D convolution operation using the sliding window approach on a xilinx FPGA. The input to the image is a 32x32 image with 2 channel on which 6 kernels of 5x5 is convolved to produce 6 output feature maps. Now assuiming I have sufficient DSPs on the FPGA, how would I parallelise the problem? After doing some research I have understood that we can either parallelise over the input or output feature maps or the kernel or both. For a 5x5 kernel, I would need 25 multiplications and 25 additions including the bias. If I have 25 DSPs operating in parallel, I can achieve this in one clock cycle. Is my understanding of the problem of parallelization correct up to now?

Now considering the input is stored in buffers and streamed to my convolution module and weights are pre loaded to the module, how is the sliding window computation performed? I realise I would have to use counters to keep track of the position of the input till the end of the N_W and N_H respectively. There is quite a lot of literature about implementing this using systolic arrays of multipliers but I am not sure I get those.

Could someone help me understand a dataflow for the convolution operation?

Any help would be greatly appreciated.
An eager student.


texts: Can a TEC driving IC such as the MAX1979 rated for TEC voltages up to 6V be used to control a 12V TEC - can TEC work under their rated voltage, with the amount of heat moved controlled by current, or would the colling performance be greatly diminished at lower voltages?


texts: How can I determine the peak power consumption of my office

texts:
how can I determine the theoretical peak power cost per hour for my computer? What is the formula I can use to calculate this? Do I need to know amperage?

My current cost per hour is $0.11/kWh

1200W power supply in my computer
2 - 110W 24" monitors
1 - 300W speaker system


texts: Inductance of a three-phase transmission line

texts:
I was studying the difference between distribution and transmission lines and read that, because of the larger separation among the conductors, the transmission lines have comparatively higher flux linkage and hence, higher inductance. I have looked at the equations and I can see that that is indeed true but it seems counter-intuitive to me because I always thought flux linkage should decrease with distance.

Could somebody please help me understand what is physically happening there that causes this phenomenon?


texts: I'm on a project that has been in production for over 1 year. The version of ESP-IDF we use is 3.3.2. Now we need to implement a MODBUS TCP / IP Slave communication feature. However I am not able to port the MODBUS protocol using the libraries available in version 3.3.2 of ESP-IDF. I tried to communicate with Master MODPOLL, but I can't even process the data. Can anyone give me a help on how to receive data from a MODBUS Master using the TCP/IP in ESP-IDF V.3.3.2? (The ESP32 will be a slave in protocol). I was search about anywere code in internet, but I not find. Does anyone have any ideas to help me?


texts:
I have been searching for this buzzer for weeks.  Does anyone know what brand it is? It is a surface mount buzzer.  I need to know the brand.

Approximate dimensions: 8.7 mm x 8.7 mm x 3.25 mm


texts:
This is somewhat of a continuation of my question here, where I questioned how a website derived the required power for an amplifier, with the resolution being that it had to do with calculating the average power consumed both by the amp and the load during a sine wave cycle.

My next question is - when determining the ratings for an amplifier power supply, why would we use the average power and not the peak power?


texts: Challenges detecting intercom buzz (Particle Photon)

texts:
I'm using a Particle Photon to detect my intercom buzzing so I can send myself notifications (so far, through text message and Hue bulb activation).

I have a five-wire intercom (diagram can be seen on page 2 in this PDF: http://www.leedan.com/IN-487.pdf) and have tried connecting either wire X (tone in) and wire 1 (audio common) using two 3200ohm resistors plus a diode in series with one of the Photon digital GPIO pins.

I'm attached an interrupt to the GPIO pin, so that I get notification when the pin goes from low to high.

Problem is I keep getting ghost notifications which I strongly suspect are from intercoms in other apartments being buzzed. I get these ghost notifications regardless of whether I have the Photon GPIO connected to wire X or wire 1.

(Apologies in advance, I don't have enough reputation to post images.)

Intercom source --> 3200ohm resistor --> 3200 ohm resistor --> diode --> GPIO

I found documentation for a strobe light that Lee-Dan manufactures for use with their intercoms. (http://leedan.com/IN-544.pdf) It seems they use wire X -- tone in -- to activate their strobe. The documentation says it's 24V pulsed at 1kHz to ground. My multimeter detects 24V as well. But I'm not sure how they only activate the strobe when that specific intercom is being buzzed.

Appreciate any suggestions.


texts: What makes a communication architecture/protocol faster than others?

texts:
Why is thunderbolt considered faster than other?
Apart from the inherent channel properties which affect the speed of data propagation, what else determines the speed of data transfer?
Of course more channels =>  parallel transfer=> more speed. Also differential signals would be much more reliable for high speed data transfer.
But how can a protocol/architecture enable faster data transfer?
I am pretty sure I am missing something fundamental here.
This is a very basic question to understand the reason for why we have so many serial communication protocols.


texts: FTDI (FT232R) chip holding the RX line high

texts:
The issue that I am having is that the device won't communicate.
I have traced the problem down to the RX line on the FTDI chip holding itself high and not letting signals through. I have spent a couple of hours looking for answers in the datasheet but the only hint that I got is that when the chip is resetting it will hold the RX line high.
This is not a faulty chip as I have tried replacing it.
I have also checked for shorting between the pins of the FTDI and found nothing.
This is also an issue that is affecting multiple PCBs, so it is unlikely that it is a random fault. It is likely a problem with the design.
here is a link to the datasheet: https://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf

Also here is a diagram of my circuit.


texts: Wideband impedance matching to an LNA with varying impedance over frequency

texts:
What's the general design procedure for trying to do a wideband impedance match to a device (in this case an LNA) which has very frequency-dependent impedance?

As a personal project, I'm trying to design an LNA for the RTL-SDR receiver which operates on the full 24 MHz - 1800 MHz range (it's very wideband, I know).

As I'm a student I've got the full versions of Agilent ADS, Genesys, and EMPro. Designing the amplifier itself in ADS is pretty easy - plop down an RF transistor, pick a bias point that's stable or near stable, and add neutralization if necessary to bring the transistor into stability.

My question is this: how do I match it to 50 ohms in and 75 ohms out? I know that I should match to the optimum impedance for low noise which I can extract from ADS (or Genesys if I export noise data with my S-paramters).

If the impedance was flat over frequency I could just do something like a Chebyshev match, but the impedance for optimum noise figure is frequency dependent. How do I handle something like this?


texts:
In the above diagram of a differential line receiver for an encoder, resistors are place between each line and its inverse. I don't see how this would lower the current of each line, so I assume it has some other purpose.

What is the resistor's role in this scenario? Is it at all related to a pull up/down resistor?


texts: How can I attach a microphone and speaker to the Arduino GSM shield?

texts:
I recently purchased the Arduino GSM shield so that I could build my own low-tech cellphone. Now that I've successfully been able to send and receive text messages, I would like to add the ability to make voice calls.

I was able to find a schematic in the modem documentation that describes how to build the earphone circuit. It seems fairly straightforward but I have a few questions:

What does "differential layout" mean?
What is the purpose of the transient-voltage-suppression diode in this circuit?
What type of device is the "amphenol 9001-8905-050"? Based on the diagram it looks like 3.5mm 4 pole phone jack.


texts: Exceeding the relay contact rating and connecting to Arduino

texts:
I have an Arduino. A suitable relay can be directly connected to an Arduino (with a flyback diode) if its coil is rated at 5 V and 40 mA maximum. However such relays have a limit on the voltages and current they can switch.

Can I exceed the contact rating of such relays if, for example, I was switching-on the relay for a short time of say 0.2 seconds and switching-off the relay for a relatively longer time (say 0.4 seconds)?

It seems that it could switch higher voltages than designed for, if the on-time is very short and there is a relatively long off-time after that quick pulse. This would of course give a cheap way (no relay driver circuit used) to control high voltage.

Is there any real danger of doing this?


texts: Planar Inverted F Antenna Sizes for Mobile Communications

texts: When PIFAs are designed for mobile communications, antenna substrate & ground plane is designed relatively bigger to the antenna's radiator patch. (i.e patch dimensions are 20x20 whereas substrate is 40x100) Is it because designers aim to represent application, such as; cell phone, dimensions by designing those bigger?


texts:
I'm a beginner in electronics, and in my free time I love making stuff with my Arduino.

As I was handling a few Bluetooth modules with my hands, I thought about static electricity discharging on the chips. I'm not very familiar with this, so I have a few questions about the topic, and I hope you could help me out to get some stuff straight in my head.

Is static electricity really so dangerous?
Can I really destroy something simple like an Arduino module if I touch it?
Assuming that I need a discharge in order to pass the electricity, how is this happening?
Anything more I should know?


texts: Can I use a 12V DC supply on this digital timer switch?

texts:
I recently purchased a digital timer switch which I assumed would work at 12V DC for powering a simple circuit which takes a 12V DC supply, and has maximum power consumption of 8 watts. So the maximum current is not exceeding 800 mA at 12V.
However, to my surprise, the timer had ratings as follows:

Now, I am unsure if this would work for the circuit I have. Can someone tell me if it would, and if it would, then how it would, and if not, then why.


texts: Altium - Handling Multiple net names for buses

texts:
I'm confused on how to solve this warning on Altium.

Nets Element[1]: RELAY has multiple names (Net Label Relay1,Net Label Relay1,Net Label RELAY1 (Inferred),Sheet Entry R1-IN(Input))

Nets Element[1]: Relay has multiple names (Sheet Entry R1-IN(Input),Net Label RELAY1 (Inferred),Net Label Relay1,Net Label Relay1)

And so on for the whole bus. I have solved similar warnings for other single lines by using Net Ties, but that is not working for this case. Altium ends up giving error that "The respective nets are unconnected".

There has to be a standard way of solving this issue


texts: Creating a three phase current system with e.g. 70Hz instead of 50Hz

texts:
I am doing magnetic field measurements on a 3-phase cable dummy, in order to develope a distance measurement system for power cables. This is a uni research project.
For a test setup I want to create a three phase current system that does not oscilate with 50Hz but something distinctly different, to be able to distinguish the magnetic fields of my own system from the grid frequency, and avoid confusion as to what caused my measurements. In my current 50Hz setup I have peak currents of about 5A. I would like similar currents (if not greater) in this new test setup. I dont need 230V, current is what I want. Something harmless like 5V or even less is fine.
It would be nice (but optional) to have pure sine waves, meaning without harmonics or noise on them. I will use a FFT of the resulting magnetic fields, and I expect a little noise and 50Hz interferance from lab equipment anyways. I would drive a simple ohm load.
One solution would be to get a syncronous machine and spin it at 70Hz with an other machine. The drawback is that that will give me more magnetic fields at 70Hz in my vicinity, and I dont have the space to get away from those nore the means to fasten them to the foundations.
Would it be easy to modify a high frequency dc-to-ac module to output 70Hz instead of 50Hz, and combine three of those into a three current system?
High end audio amplifiers can output roughly 7A, if I understand the specs correctly, and their output could be free of harmoinics. But it would also be quite expensive.
Are there other, simple, cheap and robust ways?
In any case I would need to syncronize the currents and maintain 120° phase shift between them. How could I do that?


texts: Arduino Project powered by Solar or Battery

texts:
After searching quite a bit on this topic I'm a little lost. I am new to the electronics side and am constantly learning more as I go along. I have a project where I'd like to power an Arduino Uno by a solar panel and battery. The Uno would run off the solar cell or battery depending on power is available (sun is up or down).

For simplicity, I was thinking of using a LiPo Rider Pro + a Solar Panel. I saw this came as a kit: http://www.seeedstudio.com/depot/wireless-sensor-node-solar-kit-p-919.html
It claims it will output 5V which is what I believe the Arduino requires to run (is this right?). The kit does not list the components so I'm a little lost on what size solar panel to get. I believe this: http://www.seeedstudio.com/depot/1w-solar-panel-80x100-p-633.html would output the right voltage (lists: Typical Voltage: 5.5V). However, a 1W Solar panel outputs 170mA and a 3W solar panel outputs 540mA.

On the battery I was looking at this:
http://www.seeedstudio.com/depot/lithium-ion-polymer-battery-2a-p-603.html
It outputs: 3.7V at 2000mA.

Will this solution 1) power the Arduino and 2) will the solar panels charge the battery?

Another idea is to use the Solar Charger Shield V2:
http://www.seeedstudio.com/depot/solar-charger-shield-v2-p-914.html?cPath=1_75
However, I'm still unsure about the solar panel and battery to choose.

Any guidance on this would be very helpful. I am very comfortable on the programming side, setting the Arduino to sleep, etc. The electronics side (the whole point) is a challenge I am enjoying!


texts:
I got a couple of SMC network switches (EZ Switch, SMCGS5, HW rev. A1), of which one is broken on account of something applying 12VDC to the 5VDC input. Looking at the broken switch's PCB, I can see that one component in the voltage input section is fully charred and basically vaporised. Comparing with an intact PCB I can glance the following data:

Silkscreen name: Q3
Package type: SOT-23
Markings (on intact version): N59M.
Further PCB markings: D (near the top), G, S (two pins on the lower end).

I have done extensive searching to find anything resembling a match, but other than that it is a JFET/MOSFET transistor I have only drawn a blank.

Anyone have a clue what transistor this may be, and what to replace it with?

U2 is marked FP5453 and seems to be a Dual PWM Controller for DC/DC circuits.

Here is a picture of the board (click to zoom):


texts:
I would like to connect multiple devices using DMX512 protocol. I would like to use the same cable for both power (12V, each device draws around 10W) and communication. For power I need 2 wires and for DMX512 I need 3 wires (Sig+, Sig-, GND).

Generally, a 5 wire cable would do the trick but my question, could this also work with 4 wires were Power GND and DMX512 GND share the same wire?

Power supply is a 'good' switchable PSU and the end devices are LED drivers so I don't expect any spikes, transients, sags or other power 'artifacts'.


texts:
I am using Altium Designer 14.1 and I do not know if it is an issue with this version or something else.

The problem I am having is I have a solid copper pour covering the whole board. I want to put a smaller polygon pour somewhere in the in the middle of it. No matter what pour order I put the smaller polygon pour in, when it is totally inside the bigger polygon pour, it looks like the program is defaulting the smaller polygon to an outline only. However, when I put the smaller polygon on the side of the larger one (hanging half on and half off), it will cutout accordingly: the smaller one will be whole if it is first (above in the pour order) and cutout the larger one; or if the pour order is the larger above the smaller, the smaller polygon will be cut out.

I hope someone can help me solve this. I do not know why it will not pour correctly. Any help would be greatly appreciated.


texts: Settling time in 2nd order response (circuit)

texts: I understand the definition of settling time defined as "time took to reach within +-2% (or 5) of the converged value". Then does it mean settling time cannot be defined when the response converges to zero?


texts: Does the constant on an LFSR primitive polynomial hold any significance?

texts: For the following internal feedback LFSR defined by the primitive polynomial: $$X^3 + X + 1$$ Does the constant at the end do anything to either its pseudo-random number generation sequence or to its structure? For example, if the constant at the end was a zero?


texts:
I'd like to use the PCF8574 I/O Expander in a design, however I'd like the I2C address to be set in the field. Since the datasheet specifies that A0-2 should be connected directly VDD or VSS and that no pull-up is required, can I use the following circuit to physically select the address?

Edit: So based on the comments, A0-2 may have internal pull-up resistors. If that's the case, the circuit could be simplified to this:


texts: How is power out one side of 220 only - Problem is with incoming 3-phase. But how?

texts:
[EDIT] Can someone who understands what I wrote explain this?

[EDIT 2] Sorry I didn't say I'm in the USA, the power is 110/220vac 60Hz. The input to the main power transformer is 3-phase, underground, the output is 220 with (normally) a center tap for neutral/ground. So lights and plugs are on one side or the other for 110, and heating and cooking range are 220. In this normal configuration it is impossible for loss of power on the input to the transformer to cause only one side of the 110 to be lost. Yet that is what happened to all the units in both buildings. [END EDIT]

I live in one condo unit of a two building 72 unit complex. The entire complex, both buildings run on a single 3-phase power transformer. There is some new construction down the road and their digging equipment hit some wiring and caused a strange power outage that affected many homes around the area as well as our condo units. What is strange is that all the units lost power on only one side of the 220V panel giving 110V on one side and 0V on the other side. I measured the voltages in my own panel. How is a commercial 3-phase transformer wired so that this is possible.

I am an electrical engineer and am familiar with all the normal delta and Y power transformer connections. But I have not found anything in my searching that can explain this outage. The same thing happened about a year ago, same cause. And this one again today.


texts: How does the electric field inside a charged capacitor force the electrons in a conductor to flow and establish electricity?


texts: Is there _delay_ms() active waiting in SDCC+STM8 MCU?

texts:
Is there _delay_ms() active waiting function in SDCC for STM8 MCU?

(I only found delay100tcy() for pic16 in includes)
If it doesn't exist, what is the simplest implementation?
FCPU macro is known.


texts: What is the precise meaning of "matching impedance" for an ultra-wide band antenna, and how to do that?

texts:
Well, actually, I'm not sure I really understand what is the meaning of matching impedance, even for an ordinary antenna, but I can figure out the following: if you send a signal to the antenna, then there is no reflection whenever the impedance is matched (say to 50 Ohm). I can also figure out that AT A GIVEN FREQUENCY, you can match the impedance by adding (or cutting) some length of coaxial cable, or with a suitable RF transformer.

But now comes my real problem: I did an ultra-wideband self-grounded bowtie antenna, (400MHz - 3GHZ), and I am even less sure that I understand what is the meaning of "matching impedance" for these antennas.

Assuming it is, as previously that there are no reflections, how to do such a matching ? all the matching methods I know depend upon the frequency of the signal, but here, you have no defined frequency.

EDIT: It is tempting to think (and probably to answer) that it is not possible to do an ultra-wide band matching. Yet, let take a very expensive double ridge horn antenna. They claim that the antenna is roughly flat in the huge range of 500MHz - 18 GHz (say). So, how do they match their antenna ?


texts:
I'm designing a power supply stage and I have the cascade of multiple DC-DC converters. Each DC-DC converter has an EMC filter.
The first DC-DC converter requires a capacitor between Vout and GND C1 = 2uF, and the second DC-DC converter requires C2 = 47uF between Vin and GND. Since this is a cascade of DC-DC converters, C1 and C2 will be in parallel so there is an equivalent capacitance Ceq = C1+C2.
The problem is that Ceq is at the output of the first stage and at the input of the second stage, so there is a "conflict". How can I solve this problem?