texts: What do you call a 1:3 turn ratio transformer?

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I need a small surface mount or slightly larger transformer with a 1:3 turn ratio that will triple my voltage from 3.3 to 9.9 volts.

I have been literally searching the internet for such a thing and cannot find one.  Can somebody please tell me what the heck you call the thing so that you can find it when searching for transformers?

I'm going to be running 2 PWM lines through it from an MSP430 controller and the PWMs will be doing a push-pull so that they generate +3.3 => -3.3 volts for a total of 6.6v peak to peak.  They are also generating a nice 25khz square wave.

Anyway, I want to attach those 2 wires to the little transformer and have a nice pretty square wave coming out at around 18 volts peak to peak.

This needs to be very small.  Preferably less than a centimeter square.

What do you call this thing and Where can I order one?

UPDATE (Clarification):

The purpose of this circuit is to drive a Piezo Transducer at 25khz and have it produce 110dB. In order to do this, I need a minimum of 10v Peak to Peak.

I am using an MPS430 controller which has 2 PWM pins.  I'm using a push-pull algorithm to have those 2 pins produce opposite waveforms.  So, I have 2 square waves being generated opposite of each other.  This gives me +3.3v -> -3.3v or 6.6 volts Peak to Peak.  The max voltage for the Piezo is 20, so I would like to double or triple my output voltage.  One suggestion was a 3:1 Transformer.  That seemed like the easiest way to do it.  I am open to using whatever solution works, there have also been other recommendations.  However, I would like to accomplish this with parts that do not exceed a total of $2.00.  Also, the parts must be very small.  This circuit needs to go on a board that is .75" x 1.5".  It needs to fit in an enclosure that will attach to a dog's collar.  The only power for the entire device is a small 3.7v rechargeable lithium battery.

Thanks !!


texts: Using an mbed and piezo disc to determine frequency

texts:
I am attempting to determine the frequency of an instrument from its vibration using a piezo disc and an mbed LCP1768.

I attempted this with a raspberry pi but couldn't get the sample frequency high enough to get accurate readings.
I've now moved onto using an mbed which gives much higher conversion rates using less parts.

The piezo is stuck to my guitar using blue-tac and I play an E note (82Hz).

The schematic shows the set up I have. The code that runs just reads the input every millisecond and writes the values to a text file.
Then I get the text file and put the values into excel and generate a graph.

simulate this circuit – Schematic created using CircuitLab

I would expect to see a very flat line where the DC offset is, before the guitar is played then a wave like format for the rest centered around the offset but I get a fluctuating offset to start with with values ranging from 1.52 and 1.48, which then jumps up to 1.65 between the first 163-358 samples and then back down again.

Can anyone explain how I can reduce the noise of the DC offset to get a more accurate signal?

Thank you.


texts: Calculate resistance of coil/inductor made of PCB traces

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This is to be a NFC coil/inductor of 1.1uH according do ST's eDesignSuite tool, with 7 turns.

The drawing above follows these parameters:

ST's tool give inductance value as 1.1uH, but also I need to know the resistance of entire track, in ohms.
I have measured the antenna total lenght on the layout software and it is 418 mm long.

So I have these parameters:

0.25mm width
418mm length
0.5 oz (17.5 micrometers) copper thickness

Then I entered these value of this calculator: https://www.allaboutcircuits.com/tools/trace-resistance-calculator/

And the result given by the site is 1.66 Ohms. Can I trust this value? I need the know correct value of resistance to calculate the components of RF portion of NFC filter and matching circuits.

The board will have 0.5 oz copper thickness, I can guarantee this.

Help please. Regards.


texts: Is it possible for batteries to give a false reading of being charged with a multimeter?

texts:
I bought a Stanley SL5W09L spotlight about four years ago and it has performed wonderfully ever since.  Recently however it has stopped working.

I can plug it in, and the charge light will come on - and after a little while (not sure how long) the "Completed" light will come on.  At that point I can turn on the light for a brief period while it is plugged in.  It will not turn on while it is not plugged in.

Thinking it was a battery problem (they are a bit old at this point) I took it apart (probably not the best idea) to see what sort of batteries it contained and it has 6 NIMH Grepow AAA 800 mAh batteries.  However, I tested it with my multimeter and it read out fine, specifically 7.8 volts.

Is it possible that this is a false reading of some sort, i.e. it can "burst" sufficient voltage, but can't sustain it, or are the batteries fine and I should look elsewhere for the problem?


texts: Calculate the total max power dissipation in CLASS AB push pull for reactive loads

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As worst case we can assume in reactive load the same power dissipation with the resistive part of that load. Thus for a 8 ohm impedance with phase angle of 60°, we can use \$R_L=0.5*R_{Reactive}=4\Omega\$.

Given a push-pull with power supply Vcc+ and Vcc-,

in class B max power dissipation is

$$P_{d_{max}}=\frac{2 V_{cc}^2}{\pi^2 R_L}$$

So, in class AB should be:

$$P_{d_{max}}=\frac{2 V_{cc}^2}{\pi^2 R_L}+P_{\text{quiescent}}=\frac{2 V_{cc}^2}{\pi^2 R_L} + 2 V_{cc} I_{\text{quiescent}}$$

Is this correct?


texts:
I have a task to check Kirchhoff laws in this circuit.

If I understand everything right, I3 + I2 should be equal to I1, but it isn't. What's wrong?


texts: Simple variable Capacitor circuit to feed ADC

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I need to build a humidity sensing circuit that feeds an analogue to digital converter. (This converter is then going to send its signals to a raspberry pi for analysis etc). The sensor will be about 0.5m away from the amplifier circuit (As it will be inside a climate cabinet, and the circuitry will be outside) and I have seen in my research that having a distance between the circuits causes further complications.

I have found a capacitive humidity sensor that fits my temperature range needs (IST MK33). This has a range of capacitance of approx 290pF to 340pF (showing 0% relative humidity through to 100%). I need to then convert this somehow into a suitable input for an MCP3008 ADC, I'm assuming a range of 0v-5v will work. This will then communicate via SPI to the Raspberry Pi.

I have a 24VDC supply originally but I shall also have 5V, and 3.3VDC supplies available to drive this circuit because of the raspberry pi. I looked at the circuit and answers in this question: Converting variable capacitance value to variable DC voltage level but what with the difference in the range of the capacitance value I wondered if this is still suitable?

So my question is: is the circuit in the above link still suitable? or can someone suggest a different circuit with suitable values that would work? I'm very new to all this so I've been struggling and the data sheet for the sensor hasn't got any example circuits, which normally save me! Thanks in advance. :)


texts:
I came across this schematic

It's a non inverting op-amp configuration with an audio input.

And i was wondering what the POT and R3 do? I assumed the pot to set a bias voltage but then what does R3 do? Is it a pull down resistor?


texts:
From the textbook that is prescribed for my course as well as on google, I have been told due to the diffusion of electron from n->p and the holes from p->n, positive ions are left in the n-region and negative ions are left in the p-region, where there are no free charge carriers, thus causing the formation of an electric field across the pn junction which eventually acts to halt the diffusion of the charge carriers.
However, my question is that: as holes go from p->n and electrons go from n->p, the recombination that occurs on either side of the metallurgical junction causes the annihilation of the charge carriers, so shouldn't this mean that the ions (let's just look at the p-region for the sake of the argument) with net negative charge that were missing an electron in the valence shell, that has now been filled through recombination, shouldn't this just become an atom with no net charge? As all of the valence bonds are now stable? Of course my question makes no sense in terms of charge neutrality of the crystal structure as a whole as it will no longer be neutral, but I don't understand why I am wrong.
This exact question was posed in this thread in SE EE, however, I didn't understand the answers, hence why I am asking again.
Thanks.


texts:
I have made a circuit in LTspice and now I want to subject various nodes to stray radiation. So I want to add energy to those nodes by means of voltage or current sources (and probably some impedance network around them).

My first try was this, which makes probably no sense:

I added a voltage source with the impedance of free space.

It actually looks not so bad. The shield charges more at low frequencies and shield current increases at high frequencies. But on the other hand, it doesn't make sense for the radiation to have a reference potential, as there are no charge carriers involved. Also the effect should drop at low frequencies, as the radiation can't create DC charge displacement.
Questions

Is this in any way a meaningful approach to simulate radiation on an exposed electrode? Of course, I would need to put my knowledge of the node shape/size into the description of the voltage/current source. But I cant think of how, a simple series resistance is probably not enough.

How could the unit of the field strength (V/m) be related to the unit of the voltage source (V) ? Probably it has to do with the physical size of the simulated node in real space somehow ?


texts: Trnsient simulation in multisim is a flat line, osciloscope shows good results

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I'm trying to plot results of simulation of a simple Phase shift Oscillator.
The plot looks ok in oscilloscope with an interactive simulation, but when I'm running Transient or AC Sweep, I'm just getting flat lines.
What might e wrong? Am I not understanding something?


texts: Modelling and simulating multiple-collector/emitter BJTs

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I occasionally like to try to understand how well-known integrated circuits work by building them up in a simulator and observing how they respond to changing conditions. However, I keep coming across multiple-collector or multiple-emitter BJTs, and the simulator I like to use (the one at http://www.falstad.com/circuit) does not have any model for such a device. While I am sure they can be found as SPICE models, for the sort of intuitive understanding I am trying to develop, SPICE simulations simply don't help much, as they don't permit live editing. So my question is this:

How can one best simulate multiple-collector/emitter BJTs without having a simple model for them? Can you use, for example, two BJTs with connected collector and base to simulate a two-emitter transistor? Or would that not work the same? Note that, as this is for simulation purposes only, device mismatches need not be considered.

For an example of the sort of circuit in question,

This is the equivalent circuit given in ON Semiconductors' datasheet for the LM317 linear regulator. It contains one two-emitter transistor and one two-collector transistor; the latter seems to be just a current mirror, but the function of the former is less clear.


texts: How to squeeze code for more Flash and RAM?

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I have worked on developing a feature on a particular product of ours. There has been a request to port the same feature to another product.
This product is based on a M16C microcontroller, which traditionally has 64K Flash and 2k of RAM.

It is a mature product, and therefore, only has 132 Bytes of Flash and 2 Bytes of RAM left.

To port the feature requested (the feature itself has been optimised), I need 1400 bytes of Flash and ~200 Bytes of RAM.

Does anyone have any suggestions on how to retrieve these Bytes by code compaction?
What specific things do I look for when I am trying to compact already existing working code?

Any ideas will really be appreciated.

Thanks.


texts: How to set Multi Layer Check in Altium 14?

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When defining component clearance in Altium it warns you when 2 components are too close, but, it also warns you even when the components are on different layers so obviously they can't collide.

As described here you can use Multi Layer Check for collision checking:

But in Altium 14.1 I don't see this option:

Where is this option located now? I can't find it anywhere! I even tried using Query to try to get this behavior but it didn't work.

Here for example I get a warning between Multi-Layer and Top Overlay on the same component!


texts: Finding batteries to make a stable 12 V battery-power supply

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I want to make a stable 12 V battery-power supply for RPi and LED matrix. Schematic is something like:

Battery -> 12 V regulator (- > 5 V regulator, just in case) -> RPi
                 |
            LED matrix

To supply a stable voltage source, a regulator is required and then battery should have voltage higher than 12 V due to dropout voltage.

I live in Korea. And batteries equal to or less than 12 V can be seen easily but and I cannot find such batteries in Korean electronic parts shop. Yet, I can find 24 V battery, but I think it's too much. Therefore, the only choice I can make is to put small batteries into series to provide appropriate voltage.

An Easiest way is to put 9 or 10 1.5 V batteries into series to get 13.5 or 15 V, but I doubt whether there is a battery holder that can contain 10 batteries. Another way is 6 + 9 V, but I think it has a disadvantage for modularizing since they might have different size and shape.

Is there any good idea to deal with it? I hope that the size of battery isn't too big for RPi and LED matrix.

Is a solution like below the best? (12 V / 10,000 mAh module from web)


texts: What should I expect the low end of my multimeters resistance measurement range to be?

texts:
I have an old Fluke 79-III and I'm trying to check the resistance of some resistors which should be 0.22 Ohms. Unfortunately, they are all reading 0.6 Ohms and so I'm wondering how accurate I should be expecting the main resistance function of my meter to be.

The specs from the Fluke 79-II user manual (p39), which agrees with the Fluke 79-III instruction sheet (p11) gives us:

| Function | Range      | Resolution | Accuracy      | Burden Voltage (Typical) |
| Ohm      | 400.0 Ohm  | 0.1 Ohm    | ±(0.4%+2)     | Not applicable           |
|          | 4.000 kOhm | 0.001 kOhm | ±(0.4%+1)     |                          |
| 40 Ohm   | 40 Ohm*    | 0.01 Ohm   | 5% Typical*** | Not applicable           |
| *   In 40 Ohm and 40mV ranges, thermals may introduce additional errors. To   |
|     maximize accuracy, keep both probe tips at similar temperatures.          |
| *** Accuracy applies after lead resistance compensation.                      |

I believe that I understand the resolution to mean that while I shouldn't expect 0.22 ohm, I should at least expect the meter to read 0.2 or 0.3 ohms.

Edit 1) I don't understand the accuracy rating though. Does the +2 mean that I should expect it to read high by up to two in the least significant digit? Is the 0.4% accuracy 0.4% of the 400 ohm range (i.e. 1.6 ohms), or 0.4% of the current reading?

Looking closer, the spec from the Fluke 79-II user manual confirms that:

  Accuracy specifications are given as: ± ([% of reading] + [number of least significant digits])

So B Pete's answer of ±0.2 ohms looks good.

Edit 2) Measuring the resistance of the leads by shorting them gives 0.3 ohms, so the 0.6 ohm I originally measured is well within the accuracy envelope of 0.22±0.2 ohm + 0.3±0.2 ohm.

Edit 3) Also, I did originally try the meters Lead resistance compensation (40 ohm) mode (instruction sheet p6) and measured 0.15 ohm, so I discounted it as also being inaccurate.

With only 5% accuracy, this should be correct to ±0.011 ohms.

Checking again now however, I see that when I do a Lead resistance compensation, the longer I keep the range button pressed it, the more stable it becomes, converging on a reading of 0.05 ohms. Measuring the resistor, it now shows 0.17, sum these and  (ta-da) we get 0.22 ohms.

Not bad for a 10+ year old meter that hasn't been calibrated in at least 6 years. *8')

Ultimately, should I expect my multimeter to get close to being able to measure 0.22 Ohm, or should I not expect much accuracy below a few ohms?


texts:
I am getting a burning plastic smell from the behind vents where this component is located. What is this component?

Better quality image here: https://prnt.sc/rarfs6

EDIT: The TV in the picture is not mine - it's a video from Youtube with the same TV model.


texts: DC-DC Step Down converter for Solar Panel

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I am planning to power a 5V microcontroller through a solar panel. Solar panel's Vmax = 17.78 VDC and V(open circuit) = 21 VDC.

While selecting the appropriate buck converter, should it be rated at max input 18 V or 21 V? basically, I would like to know how does open circuit voltage affect my power circuit design.


texts: Kicad PCBnew: Cannot figure out why DRC reports unconnected pads

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I'm very new to KiCad and PCB design in general (this is my first project). I have just about finished up my first PCB and upon running the DRC realized that two of the pads in my schematic were being reported as unconnected. Here is a screenshot of the whole schematic (the red rectangle is where the two unconnected pads are):

Here is the circuit with the two 'unconnected'two highlighted with the red circles:

I have tried rerouting the PWR tracks in many different ways but the DRC always reports these pads as being unconnected. Hoping someone with more experience will be able to help!

Also if anyone notices any issues with my design please let me know! The board is essentially a 6-channel relay board with some extra bits that are project specific.

EDIT: Thought I should add in a screenshot of the DRC:


texts:
How can you control the speed of an AC water pump? In particular this one.

My guess is that PWM won't work on an AC motor? I've heard that controlling the voltage will change it's speed...is this true? If so, how can I control the voltage via microcontroller (Arduino probably)?


texts: Does the current change in a Zener diode if I we increase the voltage

texts: Zener diodes work in reverse bias in the breakdown region. At breakdown voltage, high current flows. I get till here. I want to know what happens if I increase the voltage after breakdown. Is there an increase in the current or does the current remain more or less the same?


texts: Piezoelectric vibration energy harvesting

texts:
Recently I'm working on a project aiming to convert the vibration of sound waves into electricity to charge batteries using a piezoelectric material (MFC type). I was trying to use the human voice as an input, but theoretically it was not enough, so do you have any ideas about some places that I can apply my project on it (that must be noisy or can give me vibrations)?

Moreover, has the MFC material been used before in this application? If I used many pieces of it in parallel would that help?


texts:
I have a question regarding the DDR SSTL termination.

The JEDEC Standard (JESD8-9B) about the SSTL Interface for DDRs shows two possible termination methods, class I with single parallel termination and class II with double parallel termination, Figures 4 and 5 of the Standard respectively.

The thing is that the standard doesn't differentiate between uni- and bidirectional signals (such as data DQ).

Does anyone know if the termination is the same for both signal groups, unidirectional and bidirectional?

Theoretically the Rs series resistor is placed closer to the driver. But with bidirectional signals both sides could act as drivers. Does this mean we have to put two Rs series resistors, one at each side? As far as I know the DDR chips are not internally terminated.


texts:
I have a circuit that has 4 LEDs that are controlled by a microcontroller. Only one LED needs to be illuminated at a time. I would like to be able to control the brightness of the LED that is on via pulse-width modulation however I only have one PWM pin available. I do have 4 standard GPIO pins available though. I am wondering the circuit that I have drawn below would work?

I would configure GPIO 1 as an open-drain output and set up the PWM on it to control the brightness. Initially, to turn both LEDs off, I would configure GPIO 2 and 3 as push-pull outputs and drive them high. My thought it that this would put 3.3V on both sides of the LEDs thus preventing current from flowing through them. Then if I wanted to turn on LED1 I would just configure GPIO2 to float.

My guess is that I will have problems with the amount of current that is being sunk into GPIO1 if I did this with 4 LEDs. But I'm not sure?

Would this circuit or something similar work or do I need to add transistors to pull this off? The micro is a PIC24F if that matters.


texts:
I purchased several of these to drive high power LEDs on a custom project :
https://www.amazon.com/gp/product/B019W4C5IE/ref=ppx_od_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

These LEDs are to be driver at around max 0.9A around 35V, I can do that easily with these boards. I'm trying to design a better way to use the system now. I'm using the current control potentiometer as a dimmer for the LEDs which works fine. My goal is to find a slider potentiometer to replace those little trimmers. The problem is that right now those trimmers aren't the perfect way to drive the led, because there is a point in adjustment where it will no longer limit the current (I can see it on the ampmeter on my test bench) and the current will just increase as the LED heats, same under a certain value the LED will stay at the minimum 0.2 amps the board specs and won't go lower.

My goal is to find a way to set endpoints on the build so that the physical minimum and maximum values of the potentiometer match the measured values of those two measured endpoints on the trimmer, I don't know if this is possible using additional resitors in series or parallel with the slider potentiometer I'm planning to use.

Is there a way I can set the minimum and maximum value of a potentiometer with extra resistors or some other solution?


texts: How would a chip socket affect the chip?

texts:
I have a little habit of socketing all DIP chips used in my circuit (so at least if the design failed I can recycle the chips easily). Now since I am trying my hands at multimeter DIY'ing (with a all through-hole construction hence all the DIP chips) I am seriously considering side effects of placing chips in sockets.

The chipset include the ICL7135 4.5-digit ADC. On the digital side there are CD4511B/ULN2003 LED display driver chipset and a pair of GAL16V8s implementing the autoranging logic (without those there would be a few more 4000-series CMOS chips.) On the analog side there are the AD736 RMS-to-DC converter, REF03 voltage reference and a few op amps (TLC227x and OPx177 primarily.) There is also a power supply section with two MC34063s.

I think socketing digital chips, MC34063s as well as the primary ADC won't hurt (especially the GALs which required programming) but what about the analog chips? Will socketing those chips bite me? (If I can socket the REF03 maybe I can individual test and label them before plugging them into the PCB)


texts: Is it possible to make a ±3.3 power supply from 9V battery?

texts:
I am trying to make a little audio amplifier with a ±3.3V power supply I and would like to power it with a 9V battery.
Is there a solution to this?

simulate this circuit – Schematic created using CircuitLab


texts: Given load resistance with max power, how to find specific resistance within source

texts:
So I'm having a bit of a struggle with this question, at least maybe I'm misreading or misunderstanding it.  As at least from My understanding of maximum power is different, as with R2 being the resistance it is, R1 in both cases should be 0hms ideally to make R source and R load equivalent to get as close to max power as possible.

This seems wrong, but maybe I'm just approaching this question the totally wrong way.  Or my notes on the subject/looking it up don't quite give me a clear idea how to approach it and am continuing to see a incorrect method.

As trying to use thevenins and approach the circuit from the right doesn't seem to give me values I'd want, if I approach from the left and use R1+R2//R3 then I can actually make max power.


texts: Send serial data to a specific Zigbee Node with HA (NXP Zigbee HA)

texts: I have a Zigbee End-device based on JN5168 from NXP I want to release it as a lock that is battery powered. Apart from accepting the HA lock cluster commands, I need to send some custom data (some text as commands) for extra features that I want to add to the system. How can I send such data and receive it at lock? Do I have to implement a custom cluster along or is there another way?


texts: Regarding CPU speed required for USB applications

texts:
I am working on a project for developing a USB keyboard, and I am new to USB protocol and I did initial study regarding basics of data transmissions through USB.

I am now checking for USB supported microcontrollers required for my application and any development kits associated with it.

While checking some, I came through usb keyboard with Teensy which uses a microcontroller AT90USB162-16AU which has a CPU speed of max 16MHz.

But for USB isn't the required clock speed of 48MHz?

What am I missing here?


texts: Can I measure a Square-Root sinusoidally Waveform's Frequency Using a Digital Oscilloscope

texts:
I have a square-root sinusoidally-varying voltage, and I would like to determine the "frequency" using my Tektronix TDS 2014C digital scope. (I understand that "frequency" is somewhat ill-defined in the case of a square-root sine - I mean the number of peaks per second).
Is there any way to do this with my scope?
Thank you!


texts:
My LM350 regulator with smoothing caps (C1:0.33uF, C2:1uF polarized, R1:150 R2:10ohms+trimpot) does not work. It works without capacitors. I am an idiot. What have I done wrong? I tested all the connections, and they match up fine with the diagram. On Vout, there is briefly a nice voltage, then it drops. When I retest with my DMM a few moments later, the voltage is up again, then it drops.

What is wrong? Hit my stupid skull with your cluebats!

Edit: Had the same problem with a LM317 voltage regulator. I 'fixed' it by removing the caps. But I really want to know what I'm doing wrong here. The LM350 is confirmed working - without those caps.

Edit2: This question has been answered by @sstobbe. I had a bad solderjoint in an inconspicuous location. Thanks for your time everyone.


texts:
When researching optocouplers I often see that the differences between models (like the MOC3020/MOC3021) is the Ift (Maximum Trigger Current).

For example the MOC3020 has an Ift of 15mA and the MOC3021 8mA (typical), is this the amount of current it will draw to turn on the gate, essentially lighting the internal IR LED?

I haven't been able to find any resources online that explain Ift.


texts: May I connect two voltage sources together if they are aprox. the same voltage? (CP2102)

texts:
I am making a circuit in which I have two voltage sources of 3.3V:
- First is AMS1117-3.3V voltage regulator. According to datasheet, its output voltage is typical 3.3V, but could be as low as 3.2V and as high as 3.4V
- Second is integrated power regulator of CP2102. According to datasheet, its output can be as low as 3.0V and as high as 3.6V.

May I connect those two together to use 3.3V in the rest of the circuit?

If I may not, what should I do? Maybe I can void the the REGin of CP2102 and supply its VDD pin directly from regulator? Will that be right?


texts: control a resistor connection in the circuit

texts:
I am trying to use a function on a charging chip where disconnecting(floating) a  pin usually connected through a resistor to ground, disables charging (datasheet, section 10.3.8). In the default state the pin is connected to ground through the resistor:

I could either use a NPN transistor as a low side switch, ie between the resistor and ground and control it through an mcu. Or I could get an spst switch.
Is this the right way to achieve expected behavior(floating the pin on demand)? there any another(more efficient/cheaper) way to do this?


texts:
Is it necessary to connect isolated grounds for 2 different isolated RS485 nodes?
For instance the following isolated RS485 breakout board doesn't have any GND connection in the board.

https://www.mikroe.com/rs485-isolator-click

If I connect them together, will it improve the performance in a noisy environment?

According to my understanding signal ground is non isolated part of the supply as shown in figure. Is there anything wrong if I connect signal GND to chassis GND and connecting all isolated GNDs together(Without connecting to signal GND)?

Please correct me if I am wrong.


texts: Choosing the correct Gate Driver for a MOSFET in a DC-to-DC Converter

texts:
I am building my first simple buck converter, stepping down 12 V to 5 V and driving a small load of 5 Ω - 10 Ω. Something like the following:

or:

The above images both show an N-channel MOSFET. I am confused as to what would be the best option to drive the N-channel MOSFET at a 10 kHz switching frequency, keeping in mind the above parameters.

I have read here, that for an N-channel MOSFET a special drive circuit may be required to turn the transistor ON, so a P-channel MOSFET may be easier to implement.

As for the gate-driver I have seen plenty, and a popular, cost-effective circuit seems to incorporate a non-inverting totem-pole driver as shown.

I was thinking whether the above circuit would be good in my case, and simply give the PWM pulse at Rb.

- What would be a suitable gate driving IC for an N-channel MOSFET, and why?

- IF a P-channel MOSFET is more suited for this application, then I would go for the least 'complex' solution and use a P-channel MOSFET. What would be a suitable P-channel drive circuit/IC?

I have never designed something like this before, so please keep this in mind :) Any tips and/or suggestions would be appreciated!

Edit: Just for clarification.

Cost is not an issue in this case.
Simpler design (fewer parts) is better.


texts:
I'm designing a digital phase-controlled light dimmer, and I need a zero-crossing detector circuit. From what I've read, it's a bad idea to wire the AC main directly to the microcontroller through a resistor, and folks have suggested using optoisolation instead. However, I don't know how the circuit actually falls together.

It would seem elegant to me if the zero cross circiut's output is a 5V logic pulse for use as a rising-edge interrupt. But I'm not married to that idea if some other output is easier to use.

Input: 120V AC @ 60 Hz
Output: 5V pulse at zero crossing

Interesting related post, with not enough detail for me: detecting zero cross in ac?


texts: What is the center frequency and Q-factor formula for gyrator equalizer?

texts: I made an equalizer circuit as per the given schematic and now I want to change the center frequencies of each stage by changing capacitor values. I cannot find the formulae for frequency and Q online. Can anyone help with the formulae? please note that the resistors(R6, R7, R8, R13, etc) are of the same value.


texts: Why does LM324 Op-amp send out max voltage when I got 0V at the non inverter input?

texts:
I have this circuit.
The goal is that it going to control the current loop by using the NPN-transistor. My problem here is that 0V results that the output from the Op-amp is near 24V. Why?

If I'm increasing the voltage a little bit, then I got this.

And even better, If I implement a schottky diode, then I got this.

So why does the output goes to near 24V when the non inverting input is 0V?


texts: How to Put a Fuse on the DT-9205M Multimeter?

texts:
I got a DT-9205M multimeter, it has 20A unfused and 0.2A fused after I saw the PCB, surprisingly there is no fuse on the 0.2A and instead of that they put 000 resistors on it
I wonder if I could put a 0.2A fuse my self but I don't know exactly where the right spot is
also, can I replace 000 resistor with a fuse?


texts:
I have a PCB design that uses an infrared proximity detector in the form of an IR LED and an IR transistor placed with about 10 mm spacing between them. Now the problem has arisen that I need some sort of physical barrier between them to prevent crosstalk and false proximity detections.

Currently, I'm using the plastic part from male pin headers from which I've removed the actual pins and broken off the a correct length (~ 15 mm). I'm gluing these to the board with super-glue (please don't laugh).

Does anyone know of a surface-mount component that could work as an IR barrier? Obviously I could use the through-hole male pin headers to actually solder on, but I want this board to be able to be automatically manufactured. Any help or advice welcome.


texts: Circuit diagram of synchronous sequential circuit using rising edge triggered D-type flip-flops

texts:
How do I draw a circuit diagram for this system using the "one flip-flop per state" technique?

UPDATE:

This is what I have so far, but I'm getting so confused.


texts:
I'm trying to build a circuit that uses T-flip-flops to generate the sequence "CSE231-1-6" on a 7-segment display. It works fine on logisim, so there are no design-related errors here.

So theoretically it's supposed to cycle between the 10 distinct states. However on the actual implementation, the display just cycles between 2 states infinitely- "C" and "S". I tried randomly swapping the flip-flop outputs to the input of the 4x16 decoder I used, and it still cycles between only 2 random states. For example: "S" and "2", "6" and "-" etc.

I'm guessing it has to do with the way I set up the [7555] timer IC. I followed the design of the IC in the picture attached (with different resistance and capacitance). It's a circuit for a metronome. Is that the problem? If not, where should I look for errors?

EDIT: I have uploaded the actual schematic of the 7555 connections, and the rest of the circuit.

And here's the rest of the circuit


texts: A 2.4ghz simple colpitts oscillator circuit

texts: Can someone please show me how to make a 2.4ghz circuit that produces a sinewave. Maybe a simple colpitt oscillator. Componants sizes etc


texts: STM32CubeProgrammer Error: No STM32 target found!

texts:
I have a nucleo board but no mini-USB B so I hooked it up to an external STLink V2 programmer(related post).
The problems:

At first it was working as expected but after a while STM32CubeProgrammer gives an error while trying to connect:
It works 1 out of ~20 tries, sometimes even more. When it works, it works fine. But the problem with plugging in again and again is, my laptop's USB port is becoming loose. I can already tell one of them is pretty loose already.
I also tried holding the reset button and then trying to connect it, but same result(I have the reset pin connected, I don't think I needed to do that manually).
I tried different modes, frequencies etc., to no avail.

What can cause this and how can I go about fixing it?


texts: Boost Converter (TPS61322): Loop Stability with Large Capacitors

texts:
I am using a TPS61322 boost converter to convert a minimum of 1.3V (single-cell alkaline) to 3.3V (using the TPS613221A version). This device needs two passives: an input inductor and an output capacitor.

simulate this circuit – Schematic created using CircuitLab

I am powering an ESP8266 module. It runs at around 60mA with sudden 500mA spikes, all at 3.3V. The above example is from the datasheet, but it is meant to supply 50mA at 2.2V, not 3.3V. The datasheet always recommends small (10-22uF) ceramic capacitors.

A common recommendation is to place a large capacitor (1000uF electrolytic) between the supply and ground of the ESP8266 to smooth out the power spikes. However, I want to satisfy the need for this large capacitor and the need for these small ceramic capacitors in the same place in my schematic.

simulate this circuit

The TPS61322 datasheet gives the following advice:

  For the output capacitor at the VOUT pin, small ceramic capacitors are
  recommended. The capacitors should be placed as close as possible to
  the VOUT and GND pins of the device. If, for any reason, the
  application requires the use of large capacitors which cannot be
  placed close to the device, the use of a small ceramic capacitor with
  a capacitance value of 1 μF in parallel to the large one is
  recommended. This small capacitor should be placed as close as
  possible to the VOUT and GND pins of the device.

It's a bit ambiguous if the authors are referring to a "big" capacitor with a high capacitance value, like an electrolytic, or simply a capacitor that is far away from the pins. My understanding is that electrolytics with high capacitance values have a "slower response time". I am worried that the 1uF ceramic won't keep up with the switching of the boost converter.

My question is thus: Will a single, tiny ceramic paired with a massive electrolytic allow the boost converter to function properly?

The TI datasheet has equations for switching frequency and maximum inductor current, but the authors seem to give ballpark values for the capacitor values. L/C circuits are not my thing, and I'm hoping that I was right to select "Loop Stability" as a buzzword in the title.


texts: In my project, the 4051 switches two signal sources routed to the 4024 counter - an external clock signal and a manual advance clock (tactile switch). I thought that the use of the 4051 was overkill, so I would like to replace the 4051 with a simple analogue multiplexer. I had the idea to use two n-MOSFETs. In the simulation, the system works, are there any errors, something that needs to be corrected? The grey area is the original part of the design.


texts: I want to write my own implementation of SERCOM3_Handler. I put its definition in my main.c, try to compile it and get "multiple definition of SERCOM3_Handler" error. Why is this happening? The prototype of this function in the library headers is with the weak attribute.


texts: Three-phase system with line-to-neutral voltage

texts:
I have the following problem:

Consider a three-phase system with line-to-neutral voltage 268 / 0 ° V.
It is Y-connected to a resistive load with R=3Ohm per phase.
How much power does the load consume in kW (answer with one decimal).

Is the line-to neutral voltage the RMS-voltage? since P=|VLN|⋅|I|⋅cos(φ) I thought this could be calculated as I=268/30, VLN=268 V and cos(φ)=1 since there is no phase shift. So P for one phase would be (268/30)⋅268⋅1 = 2394.13 and for a three-phase system: 3⋅2394.13=7182.4=7.2kWThis is apparently incorrect... I would be thankful for some guidance to solve this problem.


texts:
Yay, me...I just got done soldering my first surface mount IC. Because I know how volatile heat can be, and with how close the tip of my iron was to the IC (especially without a socket!), I'd like to make sure I didn't inadvertently fry the IC.

Other than testing the continuity between in/outs, what are some ways to test the other pins on a breadboard before I wire the board into my project?


texts:
I want to find the settling time (i.e. the voltage at C1 not leaving a band of 1% anymore) of a step response in a circuit like this:

The step response looks like this:

As I have a more complicated case and a lot of variables I want to determine the settling time efficiently using the .meas command. The trigger would be the rising edge of V1, but how can I find the point in time, where the response won't leave my 1% band anymore? The number of oscillations is not known.


texts:
I have InnoSenT SMR-314 and SMR-334 radar sensors that have quite wide horizontal radiation pattern of over 100 degrees (see datasheet on page 3). I would like to make the sensors far more directional - thinking about 15 degrees or so. Is it possible to mount some kind of antenna on top of the sensor to solve this issue? I want a low-cost solution - will a 3d printed horn antenna work?

The radar sensor is a SMT device and will be soldered on a PCB. From the physical point of view I wonder what king of mount would be needed for the horn antenna to work. The idea is to mount a single antenna to the whole sensor and make the hole in antenna flange big enough so that whole sensor fits in there. Also not sure whether the antenna needs to be grounded to the PCB or can be left unconnected.


texts: synthesizable reg assignment + other questions

texts:
I'm at the beginning of learning verilog and some things are unclear.
Also, I'm just looking for synthesizable code.

What are the differences between this types of assignation: Which of them is synthesizable?

 reg [3:0] data_reg = 4'b1; // what kind of assignment is this? blocking, non blocking?

 vs

 reg [3:0]data_reg;
 initial data_reg = 4'b1;

 vs

 reg [3:0]data_reg;
 initial data_reg <= 4'b1;

Can I assign reg value to a wire, like:

module foo (output wire [3:0] led);
reg [3:0] data_reg = 4'b1;
assign led = data_reg;
endmodule

For the code above I get the following error: ERROR:NgdBuild:604 in ALTIUM and in XILINX ISE I get Using initial value of led since it is never assigned.


texts:
I need to make the graph for a state machine that debounces an input signal, maintaining the current up/low input signal for a certain time, and to calculate this time im using a counter.
I am having a loooot of trouble with designing the graph for this state machine so any help at all would be welcome.
I am very inexperienced with hardware so please just warn me if you need more details.

edit:I forgot to mention that I already possess the state machines of the circuit(sort of) I really only need help with making the graphs for it.
this I will be adding pictures of the signals and circuit.

edit2:following the step by step suggestion I have made an attempt to make the diagram, I would like to know if I was able to reach the proper answer.

please note:the variables on the arrows are: the entry signal,time out
and the outputs inside the bubbles are: output,clear


texts: what glue should i use when making 5, 12 V connectors (plugs)?

texts:
At the moment I'm making 5.5 x 2.1 mm DC connectors.  The connectors are typical solder lug types like you'd find at the big online stores.  I'd feel better about these if I could insulate the lugs -- the power and ground will be somewhat close together and I'm worried that if the connector is hit or crushed the lugs will short and damage the power supply.

About 30 hours ago I squirted some Liquid Nails on a board.  Today I tested the resistance and I got about a meg Ohm.  This was a pretty sloppy measurement:  I get different measurements depending on whether the probe pierces the surface, how close they are, the reading is far from stable, and so on and so on.  The point is, I'm guessing in my application, with the lugs being about 3mm apart, I'd get only 100K and maybe a lot less.  (As a control, if I merely touch the board the meter shows an open circuit.)  I'm about to test 5 minute epoxy the same way.

The question is, is there something I could use that makes more sense than me trying to guess?


texts:
All of the software debouncing routines I've seen involve waiting until some number of sequential reads of a signal return 0 or 1. That makes sense, of course. But it means there's an inevitable compromise between robustness and latency. The more readings you demand to accept a change in level, the longer the response time.

It seems like a simple alternative would be to simply ignore the input readings for a certain amount of time after an edge. If the switch had been reading 0, and then a single poll returns a 1, then interpret this as a logical 1 for the duration of the expected bounce period. Likewise when transitioning from 1 to 0.

Obviously this would still limit the maximum input rate. But it would also bring the latency for a single button press down to nearly zero, even for extremely long debounce times.

Are there problems with this approach? It seems like an obvious approach to software debouncing, so I'm surprised it doesn't seem to be used.


texts: Short circuit braking of DC motor when powered off

texts:
I am using a small 6V DC motor with a rotary encoder and TB6612FNG controller to drive it. I can start / stop / brake the motor using the controller no problem.
What I want to achieve is the following: When the motor is stopped and there is no electrical power to the controller, I want the motor to stay in "braked" state by default. For example, if the power is lost, I don't want the motor to be allowed to spin freely. I assume this would (probably) be achieved by short circuiting the terminals.
My questions are:

Can TB6612FNG do it for me? I tried reading the specs sheet, but honestly it was a bit too technical for me.
If not, what would be the best method to achieve this goal?

I am looking for the easiest and most reliable solution, have no problem to buy other controller for the task. I am also a programmer without much electrical engineering background, so I hope this question makes sense :)
thanks!


texts: Consensus on proper wiring for Cortex M 10 Pin JTAG Connector

texts:
For the past few weeks I have been working with the new revision of my ARM Cortex M4 design that I posted about a month ago, thanks again to everyone who provided me with much needed guidance and information! Anyways I am still having trouble getting my ARM to program via JTAG programmer. I am using the NXP LPC4337JBD144 ARM Cortex M4, I am using their LPCXpresso IDE and LPC-Link JTAG/Debug module. So far after many attempts I have been unable to get the JTAG interface to recognize my chip as a programmable target.

When creating this new design (the first did not work) I was very careful to check the datasheet and with NXP representatives to make sure that the hardware configuration was absolutely correct before having the board fabricated. My original design suffered from an improperly wired JTAG connector, lack of bypass caps on all voltage inputs, and the lack of jumper pins on crucial JTAG configuration pins. When setting up the JTAG connector circuit I consulted NXP support and the datasheet for the chip. The datasheet instructed me to only have pullups on two of the pins, one NXP rep told me to pull all pins down with 10k ohm resistors, and another told me to pull all pins high with 10k ohm resistors. Around that time I posted here and consulted with friends far more experienced than me, between those sources I decided to pull all pins high with 10k pullups.

Over the weekend I swapped out the chip maybe thinking that I might have damaged the first one but I was still unable to get it to program,  so I went through all the datasheet but I could not find a solution when reading through the section on the JTAG interface. My next thought was to look at the evaluation boards made for the same ARM that I am using. I discovered that the boards from Hitex and Keil had unique JTAG connector wiring, both different from what NXP instructed me to do. This discovery has been rather confusing and what I really would like to know is which is the right way to wire it? Is there a standardized wiring scheme meant for all Cortex M ARM based micro?

Here is a schematic document I made illustrating the different configurations as well as the reset circuit and TRST/DBGEN jumper pins.


texts: Will light turn on in a closed circuit for a moment if a diode stops electric current after light source is reached?

texts:
I drew an example of the closed circuit I was thinking of for my question. Below I have the diode stopping the electric charge after it has already passed through the light bulb. My assumption is that the light bulb will flash once. Am I right?

50 points to whoever can find the duplicate question.


texts: Split rail toroidal power supply transformer amperage question

texts:
If a toroidal power supply transformer says for example "15-0-15V 1A" on its label does that mean it's 1 amp for each rail, or 1 amp for total 30 volt output when not using the split?
I looked online but couldn't find a definitive answer to this. Thanks.


texts: Battery life calculation using Nano, NRF24L01+ and window magnetic reed switch

texts:
I'm trying to make my own home wireless security system.  I will be using probably 3 AA batteries to power these devices.  My problem is that I need to know if the batteries will be enough to power the devices for at least 6 months.
Below are the details of all the devices I will be using:

Mini Nano V3.0 ATmega328P Microcontroller Board w/USB Cable For Arduino
Makerfire Arduino NRF24L01+ 2.4GHz Wireless RF Transceiver Module
uxcell MC 38 Mount Wired Door Window Sensor Magnetic Reed Switch Recessed

Below are some project requirements that might be useful:

For the Nano, I want to put it to sleep using delay(2000) in the loop() function.  The Nano will be the one checking the window sensor.
I will be using a project enclosure of about 4X4 inches.

If this will not be possible maybe someone knows of other devices that use less power that will be more suitable for this project? I would prefer something easy to use like Arduino Nano with USB so I can easily program it.


texts: Solar power pump - Design critique and help

texts:
Okay so, I have a design that 'works' on the breadboard. But I feel like it could use some improvement. Here is my current design:

simulate this circuit – Schematic created using CircuitLab
MAX9064

Now I think the solar power collection part is okay. But the pump driving part seems like it could be improved...

The solar panel will generate around 9V which is stored in a capacitor bank and converted to a 1.8V supply with a maximum current of 100mA. I haven't tested this thoroughly in real world conditions, but all seems to be working as expected.

The motor requires more than 100mA for a cold start. So the idea of the second part of the circuit is to charge a capacitor up before switching the motor on to deliver the required current. On switching the motor there is a voltage drop of over 100mV, so positive feedback is required to generate a fairly large hysteresis band to cope with that.

The MAX9064 has only 0.2V reference which I think could be an issue.

I've tried with a few different R values. I've been going for a switching voltage of 1.7+ with around 400mV of hysteresis. With R3 and R4 at 10Meg I seem to get switching problems with the motor on. Rapidly switching, it does run, but not well.

Moving down to an R3 of 100K causes big problems with accuracy of the switching voltage and I've had trouble getting it to switch at the desired level.

Currently using R3 of 1Meg, R2 of 33K and R1 of 220K has worked best. The switching accuracy is still a bit off (on the lower end than it should be). I've left R4 at 10Meg.

My goal is obviously to deliver a much current to the motor as possible, while having enough accuracy to switch somewhere between 1.7V and 1.8V and deal with the voltage drop caused by switching. So what can I do to improve on it? I think C2 at 10F is probably overkill and maybe I need to get some noise reduction going? I'm also worried that the 0.2V ref might be an issue, though I could use a different comparator if that is the case.

Thanks for any input!

Update: I made a small change to the circuit which seems to have greatly improved it as follows:

simulate this circuit
The addition of a 100nF ceramic in the location shown greatly improves the output performance. I also went back to higher R values, but that wasn't doing much.

The problem is I have NO idea why adding the cap there made such a massive difference???


texts: How in CDMA mobiles receiver gets unique code to decode its respective signal?

texts:
Transmitted data in CDMA mobile is encoded with a random code. Receiver requires this random code to decode data from the received signal.

From where the receiver will get this random code?


texts: UTD2025CL oscilloscope - help with these displays

texts:
I have some concerns about a UNI-T UTD2025CL oscilloscope:

Why there is more than 1 sine wave in the screenshots? Is that normal? The screenshots show a TL431 regulator output. The coupling is set to AC, the trigger is set to CH1.

While measuring output of a 50Hz 24Vac transformer, the trigger notification on the DSO screen is switching quickly between "Trig'd" and "Armed"? Is that normal?


texts: What kind of motor would I need to turn this central heating valve?

texts:
I often forget to turn my central heating down when I leave the house, so I thought it would be cool to make a device that could do it for me and to have a website where I can check and change the heating. I was thinking about using the Arduino with an Ethernet shield for this. Programming won't really be a problem. I am however totally new to motors, and I have no clue as to which kind of motor would be suitable for this. This is the knob:

The idea is to have a motor sit next to it and attach four arms to it that fit in the corners of the knob. I'll also add a potentiometer to be able to control it when I'm home.

So, is this possible? Thanks!

Edit:
So I understand this is not the best solution and that it would be better to hack a thermostat or use an electric valve, but unfortunately both of those things are not an option for me. I have just one radiator (this one) and that's it. So I'd still like to know what kind of motor would be suitable for this. I was thinking a servo would be good but that limits me to 180 degrees of rotation, and I need a little bit less than 360. There are ways to get more than 180 degrees, but that would remove the position feedback thingy. Do I even need that?


texts: Help needed to identify pins of power supply

texts:
I could find no schematic nor data sheet online for what appear to be DC power supplies. There are two terminals on the smaller ones labeled output +, -, three pins labeled input 1, 2, 3 and a lone pin labeled INH. The larger boards  are nearly identical except the have an additional smaller transistor and two additional +, - output pins bridged two the first two.  Please help me identify these. I have a three boards of each type that came with a four 24v AC powered CCTV cameras. Is a 3 phase voltage requirement possible? Would it be a bad idea to apply 120VAC to two pins? I would be willing to take the risk but don't want to fry any of them unnecessarily. They are labeled: "POWERTEC INC. - Chatsworth CA", for which searches returned no electronics manufacturer. Then below: "WARNING: THIS UNIT MUST BE PROPERLY CONNECTED TO AVOID DAMAGE. PLEASE REFER TO DATA SHEET", no data sheets were included nor found online.

Note that the cameras are 24v AC. The cameras are NOT what I am interested in, I have use for DC power supplies. They are not labeled for voltage. On the big cards the large wired pot is labeled 'E out ADJ' (output voltage?), the twin pots are labeled 'OVP ADJ' and 'I lim ADJ' (What is OVP? Is input variable?). It's larger transistor is an RCA 2N3055 CVV 3F. The small transistor is labeled RCA 13159 2 CHG 3J. It's large cap is labeled 'STM 32-13007-001 39CS15JL93 9000 MFD 15VDC 11C07315 85(deg)C'.

The small cards pots are identical. It's transistor is 'RCA 13002 3 CVFJ 3C'. It's cap is labeled 'STM 39C30HH182 32-13007-009 1800MFD 30VDC 11607221 85(deg)C'.

What is the 'INH' pin?

Thanks for insight!


texts: (Basic) BGA Multi-layer stack-up/PCB layout question

texts:
Getting into BGA's recently if nothing more than necessity as all the 'cool chips' are only today offered that way.

Still, I am missing something I feel essential when it comes to the layout/design/understanding of now layered power/ground planes. SMT alone is pretty straight forward and simple and I feel I gather the concept, but don't yet understand the implementation....

As an example reference a pic from this Lattice BGA layout guide:

Signal planes, fan-out, top and bottom vias are very clear... But, to be honest, I cannot figure out exactly what is 'happening' with the power and ground planes... Or for EX for the power layer there are obviously two domains here [VCCCore and VCCio], which are connected/separated... But obviously no 'traces' otherwise.... I mean are the red and green areas just a 'copper pour' ? and if so why do the vias to the same plane need to overlap ?

There may be other, more complex reasoning behind this, but I feel as if the 'basic' answer ought to be simple, but I am just not 'getting it'... 'seeing it'... (i.e. even as referenced above, well, okay, separate power planes-- Either the trace is inverted in black or there is only a single isolated pin (to the right) in that one domain or I am just really not understanding....

Would appreciate any advice, resources, references to better my understanding.


texts: What's the device - S4L85H1X01 IC by Samsung?

texts: I found S4L85H1X01 IC by Samsung in HP PSC 1310 (Q5763A) inkjet printer / scanner and can not obtain proper datasheet. What's that device? It's in TSSOP-20 package.


texts: Regarding Direction calculation using Gyroscope,Magnetometer and Accelerometer

texts:
We are using a MEMS tri-axial sensor which has an Accelerometer,Magnetometer and Gyrometer. We have also calibrated the Accelerometer and Magnetometer.This sensor package is used in a borehole application. We have calculated the deviation of the borehole using the Accelerometer. Now we are stuck with the direction calculation free from rotation (i.e if the sensor rotates, the direction should not change).Is it possible to calculate a rotation free direction using the three inputs we have (Accelerometer, Magnet, Gyro)?

Please find the attached image of Mechanical orientation of sensor.


texts:
How can we find the value of beta for a transistor to enter in a saturation region?

For this, the existing value of beta is 50.


texts: Continuous light: do LEDs flicker like fluorescent lights?

texts:
Continuous light - do LEDs flicker like fluorescent lights?

Under fluorescent light there is a flicker.

As I understand LEDs work only with DC current, thus they have a AC to DC transformer circuit pumping electricity into them. That would mean that they emit continuous light.


texts: Electromagnetic waves antenna via microcontrollers (Transceiver and receiver)

texts:
I have two Arduinos: Mega and Nano, and 2 steel pieces of wire as antennas which I stuck directly in the pin slots.

I've setup my Mega2560 to generate an alternating current on one of its pind (PWM digital pin 8) so now I have a sinusoidal signal (0-5v,40mA) as you can see in thid picture:

A second Arduino (Nano) I've setup as a receiver. I stuck a wire as an antenna in Analog Pin 1, and connected it with a pulldown 1k resistor, so there won't be any noise. You can see in a picture below AnalogRead function of this pin (I've touched the antenna a couple of times:)

How do I have this sine wave signal on my Arduino Nano (receiver A1 pin) via my antenna and electromagnetic waves in simplest way that possible?

Should I use this dipole type of antenna instead of just a wire:

Or  this coil type antenna? I've messed up, and can't find any examples of basics of EM waves working with Arduino, just an premade radio frequency modules.

p.s: Here is an interesting tutorial I found recently, but it only implements a "transceiver with a wire as an antenna" part of my question.


texts: Switzerland - IEC vs UL vs VDE vs CSA ratings

texts:
I'm currently looking for a new connector for a PCB embedded in a household device with ABS housing.
The connectors are intended to have 3 phases, 1 neutral and 1 ground wired to it. On swiss electrical grid, the highest VAC voltage is 400VAC (+/- 10%) between two phases.

My confusion comes from the datasheets of the connectors:

There are different voltages specified for each category (I/1, II/2, III/3). If I'm right, household devices like mine are in category II/2. Is it right ?
The other confusion comes from certification institutes. The datasheets sometimes specify ratings from different institutes like UL/IEC/VDE/CSA. For the same connector the rating can go from 250VAC to 630VAC. So which ratings do I have to take in consideration for Switzerland ? I can't find any information about it.

For now, I'm using the connector 691352710005 from Wurth Electronics but it's rated for 300VAC (Working voltage). So I'm afraid it can cause us troubles in the future. The connector was chosen by the external company which designed the actual PCB but I want to change it. Or is it safe to use it anyway ?


texts: What parameter is used to choose the direction of the flux in a magnetic circuit?

texts: I don't get why the \$\Phi_{1}\$,\$\Phi_{2}\$ and \$\Phi_{3}\$ are supposed to be running in the way depicted here.


texts:
I'm using LSM9DS1 accelerometer which I configured with 16g range.

I left the device without movement and I got following accelerations

x : 0

y : 0

z : 1300

the device is subjected only to gravity, hence the positive value got in Z

my question is what's the origin of the value 1300, the earth gravity acceleration is 9.81 m/s²


texts: How to begin programming with STM32 Discovery

texts:
I am a complete beginner to Microcontroller programming. I have a new STM32F4 Discovery board and I am clueless on how to begin with a simple blinking LED program.

I have installed Eclipse with the GNU ARM plugin and now I am wondering what to do next. I have found a few tutorials online but most of them use other IDEs than Eclipse. I am not sure if Eclipse is the best IDE for uC programming. If yes, could someone point me to tutorials for such programming for beginners.


texts:
I have a question regarding MATLAB Simulink if anyone is familiar with the software.

I usually have no problems creating basic models like this one below:
I know the image is rather small.

It is basically 3 phase generator with internal series impedance > VI series measurement block > series ammeters > RL series transmission line impedance > RL series load with load volt meters.

But however, sometimes when I run my circuits and enter my oscilloscope, I don't see a pure sine wave. It appears rather choppy. I get the correct voltage and current values in my displays as I have calculated them also. I am nearly sure all my parameters like frequencies, base voltages etc are all typed in correctly.

This is what my scope looks like:

Any tips or ideas?

Thanks.


texts: How to "spread linearly" the force of a solenoid

texts:
For a pet project of mine, I'm interested in finding a tubular solenoid which force is spread linearly over a longer length. The project is based on IA and uses a programmed controller (and sensors) to feed several solenoids (the question is for one solenoid) quickly in order to "grab" something falling vertically, from below, this silently (done) but also a bit more smoothly (the problem). Currently, while the programming seems to work, the test prototype with two solenoids lack control. Basically the solenoids force goes from 0 / 1 [didn't try to control current yet].

I bought and tried from the Net, something like

but the force is basically 0 / 1... meaning the force grows exponentially over a short distance.

Ideally, the force would be linearly spread over a length I decide. Thus my question

  Preferably with only one solenoid, how to choose/select the core and wires in order to spread the force over a longer length (i.e. not exponential growth)

If 2+ solenoids are necessary please explain how you would arrange them to reach such result (1 is preferable though).

Note: if that helps, the current applied to the solenoid can be precisely controlled from a chip.


texts:
Recently, my headphones mic stopped working and I figured it was probably the plug (although I'm not 100% sure). So what I've set out to do is to solder a new plug on. I asked my dad and he said the house had some solder, and even the solder iron. However, there are no lables on the solder, and my dad can't remember what type it is.

How do I identify whether it is the type used for plumbing or the electronic type? And how do I identify whether it has a hollow core of flux in it?


texts: What is the output in Figure 3-19(a) if the input voltage is increased to a peak value of 20 v?

texts: Will it be the same as if the input voltage is still 10 V? Or the zener diodes will breakdown (get damaged)?


texts: how to define a relative bandwidth for the signal with the equation K/w^2

texts:
I have a straight line with a slope. Thus its fourier transform is K/w^2. I wanted to estimate its relative bandwidth(Wont it be dependent on the slope?[1st question]).
If the answer for 1st question is yes , the dominant pole is always 0 right?(infinite)
then 99% area or such approximation does not make sense, so how to do such approximation?


texts: How much should be the trace width on PCB for max. 15A from 3 Phase AC Source?

texts:
I have source 400V 50Hz 3 Phase. Each line is 230VAC and maximum current passing by is 10A. This source is connected two motors and one AC/DC converter (24V out) and it is connected to control circuit. For the power part, I used 2.5 mm^2 cable for connection. Everything worked well and now I would like to make it on PCB. However, I don't know how much trace width should I use?
Furthermore, I have no idea what external, internal layer means (I guess it refers multilayer PCBs out and inner layer), I don't know what exactly means temperature rise.
Low current part (control board) I have already made but power part I don't have much idea. I would be glad if someone can help.


texts: Input and Output terminals of the transformer

texts:
I want to use low voltage ac supply for my projects. I have got one from my computer SMPS.
But its winding terminals are making me confuse.At one side,there is 2 terminals(in the picture,it is down side),and the resistance across these terminals is 1 ohm.
The other side has 6 terminals,with 3rd and 4th one shorted.(in picture up side). The resistance across all those terminals are also nearly 1 ohm.
And lastly,there is a projection from the transformer (shown in picture). I don't know ,what the crap it is.

I want to know the exact input and output terminals.


texts: How to prevent 7 from displaying in digital dice roller circuit?

texts:
Anyone got any ideas on how to prevent 7 from displaying?
There are some cheap ideas that my professor said were bad: one being delaying the clock and the other is altering the display somehow.
He said the best solution would be something that does something with the feedback function (which I believe is the XOR gate) and automatically re-rolls when 7 is chosen randomly.
I've tried messing around with the set for the flip-flops and was able to get rid of 0 from the output.
I know that if I mess around with the reset I'll mostly end up in an unknown state, not sure if it's a better idea to switch to a jk-flipflop.
What I'm not sure about is what I would do with the feedback function to re-roll the 7?


texts: 555 timer as FM transmitter vs. Tank Circuit

texts: This site seems to suggest the use of the 555 timer in astable mode to generate frequency modulation from a source.  The typical transmitter uses a tank circuit with an inductor and trimmer capacitor or an inductor and transistor like this one. I would rather use the 555 timer version because of my bad experiences with inductors and the availability of pieces. So my question is first which do you think would have the farthest transmission range and also how would I change the frequency of the 555 timer circuit? Any input appreciated.


texts: Can oscillations occur in VHDL with concurrent statements?

texts:
Imagine we had two concurrent statements that depend on each other:

ARCHITECTURE Behavior of xxx IS
BEGIN
    s1 <= (A and B and s2);
    s2 <= (B and C and s1);
END Behavior;

So, if A or B or s2 changes, s1 is updated. Then, since s1 updates, s2 is updated. Since s2 is updated, it would seem that s1 is updated again .. etc.

Can such things occur in VHDL? Of course in a real system, then the output would oscillate, but I have very little insight into how VHDL code gets synthesized into hardware.


texts: How to measure DC voltage without knowing which pin is ground

texts:
I have a connector from the motor controller to the display on my e-bike that has five pins in it. The system is powered by a 52V battery.

I would like to find out which pin carries the battery voltage, and which one is the ground. The three other pins are much lower voltage, sending 52V to them would cause damage.

My issue is that I don't know how to safely make the measurements with a voltmeter without risking shorting the 52V pin with one that wasn't the ground. Can I just hook up my voltmeter's black probe to the (metal) frame of the bicycle and safely measure the pins in the connector one by one?


texts: I wrote a python script that automatically generates and runs LTspice netlists. It runs perfectly on both Windows and Mac. Few of my friends, with whom I am working on this school project, have Linux. This makes it hard for us to run the same python script, since they cannot have LTspice (Reference). I read that Ngspice runs perfectly on the three os, however, I am still finding it a bit hard to convert all the LTspice Netlists to Ngspice ones... I will basically have to rewrite my entire script. Is there a workaround (apart from using WINE)?


texts: How is the ampere percentage of a circuit breaker selected for different loads

texts:
This document below specifies rules according to which a circuit breaker is selected, it specifies Maximum Circuit Breaker Size % of Current for different loads in table 2

http://www.fs.fed.us/database/acad/elec/greenbook/3_basicdesigns.pdf

But what I fail to understand is how are these percentages calculated? What is its formula?
Any kind of help will be appreciated

Thanks in advance!


texts: What are the typical tasks of a Design Verification Engineer?

texts:
I'm quite confused on what should be the typical tasks of a Design Verification Engineer in ASIC Design. In my experience these were the things that I do:

Create verification plan
Create testbench architecture plan
Build the testbench
Create the testcases
Run RTL regression to verify the DUT until coverage is 100%
Run GLS

Now, I don't know if the following are still the responsibility of the Design Verification Engineer:

Debug the RTL (Is this a task of the RTL Design Engineer?)
Linting (Is this a task of the RTL Design Engineer?)
LEC (Is this a task of the RTL Design Engineer?)
Synthesis (Is this a task of the RTL Design Engineer?)
STA (Is this a task of the PNR Engineer?)
Debug timing (Task of RTL Design Engineer or PNR Engineer?)
Generate SDF (Task of RTL Design Engineer or PNR Engineer?)

Thanks.


texts: What type of connector is this? Where can I get a new one and a cable around 2metres long for it with 20 strands inside?

texts:
For reference: I am incredibly new to electronics.

The attached photo is of a cable that connects two halves of a split keyboard I just bought. My hope was that this cable would have been 4 wires or something which I would have been able to desolder it to extend the cable length. But instead I find this 20 wire cable connecting both halves with the connector on the end.

So now I am thinking maybe this may be a standard type connector and a standard type of cable I may be able to find online instead of having to do a bunch of soldering with very tiny wires. Any thoughts on how to proceed? Maybe where to find that type of connector and a 20 strand cable in the 2 metre range?

Thanks


texts: Can I replace a 0.1µF capacitor with 1µF in this circuit?

texts:
I want to make a traffic light circuit but the problem is that I don't have a 0.1µF capacitor.  I do have a 1µF capacitor, would it be OK to replace it?

The circuit diagram I am using is shown below and is taken from an online tutorial:


texts:
All my QFN footprints are made with the Altium internal "Tools -> IPC Compliant Footprint Wizard". I get nice footprints with vias in the thermal pad.

When I try to place one of those footprints to the PCB, I get an short circuit violation between the via and the pad. (Shown in the second Image).

How can I correct the rules to allow this vias?
I have tried to make a rule (Image 3) that allows short circuit between pads and vias. But the problem here is that the vias are not connected to any net (no Net). If I want to connect them, I have to unlock the primitives and set each via to a net. This is a real ugly way of solving this problem :-(


texts: What would be the consequence of the inductor saturating?

texts:
The following is a section from a book where it is talking about decoupling by LRC at supply terminals. I highlighted the sentence where I didnt understand:

I read that if an inductor has an iron core, increasing the current after a point saturates the magnetic flux. Thats what I know about sauration of an inductor with an iron core.

But what is this highlight talking about? Is that assuming that the inductor has an iron core? And most importantly what would happen if the inductor saturates in that context?


texts:
i've just done this tutorial: http://www.arduino.cc/es_old/Tutoriales/Rele

it works great! i've done it in a breadboard (with two 5v circuits for test) and then soldered (for just does not have 220v on a breadboard) and it works well for 1 light.

now i need more lights and i thought to make a relè for switch on/off a multiple adapter.

the thing i want to know: the pin of the relay are thin (just all other 5v-breadboard-based component) and i thought that more volts you have more bigger have to be the wire.. how many normal 220v ac light bulb can i control with one relay?


texts:
I am looking for something similar to this connector, in SMD form.
Any hints?


texts: Strain gauge measurements with carrier frequency

texts:
In near future, I would need to do strain gauge measurements using HBMs instruments, the amplifier will be MX1615B.
In my case, the gauges will be placed near a 50Hz gearmotor and run with VFD.
As far as I understand, this can cause a lot of noise to measurements and when I discussed with HBM supplier he suggested me to use carrier frequency of 1200Hz.
With carrier frequency of 1200Hz the bandwidth will be 400Hz, and the supplier thought that would be enough.
Well, because I'm not from electronic background I tried to study the subject but still can't get my head around it.

So how much data I'm able to transfer from my measurements?
How do I know if it is enough for me?
What does this 400Hz bandwidth with 1200Hz carrier frequency mean?


texts:
On the L298 datasheet (http://www.sparkfun.com/datasheets/Robotics/L298_H_Bridge.pdf), the Bidirectional motor control application example (Fig 6) shows that the need to be two diodes connecting the ground.
I understand that you connect a flyback diode to the V_supply for EMF protection by allowing the current to flow back into the motor itself. However, why is there a need for a diode connecting to ground? I don't see how the diode can be made forward biased.


texts: Can capacitor operate under voltage exceeding its "Maximum Working Voltage"?

texts: For example, I have a capacitor like this - https://aliexpress.com/item/32779085832.html. Its "Maximum Working Voltage" equal to 70V AC. Can I use this capacitor in 220V electrical circuit for 20 seconds without damaging capacitor?


texts:
I made a circuit for a tape (or block) LED that will turn on with 12V.
I had two 9V batteries, so to convert them to 12V supply that is suitable for LED I used two linear 8V and 5V regulators - connecting them together  gave me an almost 13V supply.
That worked but what happened is that after a few days the batteries wasted and drops to 0V and 2V. (The lights were off and that happened.)
What's the problem in my circuit? Are the linear regulators wasting power?


texts: Common audio signal voltage range on Line out connector

texts:
What is typical audio signal voltage range on Line out connector of consumer electronic devices? (Vmin/Vmax)
I need specify Input voltage range to calculate op-amp. Vin pk-pk, Vin Midpoint, or Vin Min, Vin Max I know the line level depends on the device type, but in general?


texts:
In 10GBASE-R specification, Gearbox is defined to take care the data width adaptation between PCS & PMA. For example, after the 64b66b encoding, the PCS data width will become 66bits.

The gearbox will adapt the 66-bit datawidth to whatever data width that PMA is support.

May i know if we can have a PMA with serializer factor of 66. Does that mean Gearbox is not necassary or not needed in this case?


texts: What is the difference between the transition frequency and unity-gain frequency? I hear these terms being used all the time and I thought they referred to the same thing (the frequency at which the gain is unity) but I want to make sure I am not misunderstanding anything.


texts: Why "substrate" is exposed through a "do not connect" pin at all?

texts:
I've were reading through MOC3041 opto-isolated triac when I noticed this part:

"Substrate". It's also repeated later on one page down further, but there's no explanation. I guess that might be the silicon substrate upon which the device was build, and I can imagine that actually connecting it to a wrong thing could make things soon pretty bad. I also know that in discreet MOSFETs the substrate is very often tied to the source pin, so if the substrate here wasn't internally connected to anything for some reason, and even the datasheet says "do not connect", then it seems quite obvious to me, that, well, it should be left not connected. OK.

But if that's the case, then I guess that leaving it internally not connected would be the easiest and safest way, and I saw that a lot in various devices that had to be packed in some standard casing that had too many pins.

Then why expose the substrate at all and then instruct designers to leave it floating?
What's the use for this?

I've also seen this question for a similar device, it could shed some light, but unfortunatelly it's unanswered.


texts: I've been arguing with a colleague whether it is a sensible solution to clean dusty PCBs with compressed air. While I think this is the best solution (nothing touches the PCB), he claimed that spraying off the dust can cause ESD, because the charges that may have accumulated in the dust win't bleed off in the process (and it's better to leave everything as it is). I'm not really convinced by this argument and my (limited) knowledge of ESD production doesn't help getting peace of mind in this matter. What is your input?


texts: Xbee pro s2c 2.4 ghz 10dbi Antenna and its effect

texts:
Just wondreing  how to increase the range/distance of communication between two xbee modules operating in API mode,

we are considering to replace the 2.4 ghz antenna of 5dbi gain with 10dbi high gain antenna, does it work and fit into our need, the only term i cannot understand is the power requirements of the antenna.

Does antennas draw more power if their gain is higher? And also the xbee pro s2c module power is limited to 10mw as per the digi website.


texts: PCB design for LEDs on aluminium board in Eagle

texts:
I'm making LED light panel which will contain lots of high power Surface Mount LEDs connected in series. I'm using the LUMILEDS Luxeon Rebel Series LEDs which has three pads on each LED, an anode, a cathode and a thermal pad. Therefore, I would like to use an aluminium board so I can attach a heatsink to the panel.

My question is how can I use Eagle to design a board for aluminium boards where the thermal pads are connected to the aluminium board? Also, what files do I need to send the PCB manufacturer?


texts: High current draw through DC-DC boost circuit

texts:
I currently have a simple circuit below which works fine but I am confused with the readings I am getting for when the Atmega1284P is put to sleep.

When it is operating I get a current draw of around 18-20mA. When it goes to sleep with everything disabled. Ie BOD, Timers etc. it is still drawing around 10mA. The atmega should only be drawing a few 100uA when asleep.

I just wanted to check if what I am seeing is correct as I guess the boosting circuit will need to use power to keep the Atmega powered in sleep mode. My next design will power the Atmega directly from the Lipo battery but I would like to learn from this.

I am measuring the current at TP1.

So the question is; if the Atmega1284 is using around 250uA should I be seeing ~10mA of current draw at TP1 because of the dc-dc boost converter circuit?

Thanks guys!


texts: CURRENT TRANSFORMER 30A / 5A Interfacing with AVR Atmega32 ADC

texts:
I am trying to Calculate Current of 1HP Motor uses with Motor Starter Box. Initially when Motor is started i can see current shoots upto 20-22A on analogue meter in starter box.

I want to measure this Current Continously while the motor is in operation.

For that purpose i have purchased 30A / 5A (CT) (12 Turns wound on CT) AC Current Transformer 30/5 A (Two turn Primary)

on 30A AC load it will provide me 5A AC output on secondary (CT output). Burden Capacity is 2.5VA. I am confused with burden resistor calculator and how can i interface CT with ADC of atemga32.

Please can anyone help.


texts: What are the effects of powering AC devices from a square wave?

texts: I've been playing around with some ideas about building my own inverting power supply, to power AC devices from a car battery. I've heard of designs that just feed a square wave into a transformer to get the mains voltage output, but I've also heard vague claims about how you shouldn't do that. In what ways can powering devices engineered to run off a sine wave with a square wave impact their functioning?


texts: Can inductors always be avoided in analogue filter design?

texts:
Inductors have always been described as big, bulky and extensive to me in text books. It seems that people don't like them. However, I have seen that inductors do appear in filter design due to frequency response nature which is opposite to that of the capacitor.

I know that a certain circuit made using op amp can "convert" a capacitor to an inductor. Does this mean that inductors can always be avoided in filter design? If so then why are inductors still used in filter design in real world applications?


texts: SIM cards not responding to SIM908 module

texts:
I have a SIM908 module on a dev kit board. I have three SIM cards that are all detected fine on the previous version of the board. However, the v2 only detects one out of the three SIMs. I put the scope on while it was trying to detect one of the non-working ones and saw that it attempted at 1.8v and got no ATR back, then at 3v and got no ATR, then gave up (neither module supports 5v SIMs, but I gather they went out in the 90s anyway).

The module is adequately powered (2.5A continuous, 4A peak; module is only 2A peak). I have confirmed good connectivity between the module pins and the SIM card holder.

To reiterate, all three SIMs are detected by the v1 board, which uses the same module. What could be wrong, and what else can I try?


texts:
My mother brought me this ultrasonic thingy that is somehow used on your face. The problem appeared pretty simple, just a visibly broken wire. It got more interesting when I opened it up though.

First, the reason it stopped working was because the red wire(assuming DC+) was broken. The black wire (assuming DC-) was fine.

There was also a brown wire that had broken off right at the solder point, I'm guessing it was the ground since I found the little nub it broke off from on the metal plate that runs throughout the whole thing and comes out the other end for the face touching.

I marked them here

The unmarked blob of solder (at top left) is also on the metal plate but appeared to be unused.

Then when I was stripping the wire, I found another wire that was cut off right where the other wires were previously stripped from. It is blue and there was no remnant of the rest of it inside the device. Not sure whether it was cut off on purpose though since its tip was slightly stripped and looked like the result of a wire being cut from wear and tear.

Anyways, the device works even with only the red and black connected. I also soldered back the brown one to the plate. Should I just ignore the blue one though?


texts: Transformer: Number of turns om primary winding

texts:
I'm researching electromagnetism for a guitaramp project. I would like to experiment with different homemade transformers.

Find myself stuck trying to get a grip on the effect of the number of turns on the primary winding in relation to the risk of a saturated core. One the one hand more turns imply more inductance according to Inductance (L) = number of turns (N) times magnetic flux(Wb)/current (I). On the other hand it is well known that decreasing the number of turns on primary will increase flux density and the risk of saturation. I guess it must be the relation between number of turns and current that gives the answer, but find it hard to find good explanations. Anyone with a good advice?


texts: Why do charges not lose potential as they travel through the circuit before reaching a resistor?

texts:
Voltage is defined as:

Given the circuit:

Why would potential not drop, from the point differentially away from the positive terminal on the battery, to the point I have labeled. I understand that charges lose energy in resistors due to inter lattice collisions, where the acceleration generated due to thermal motion and voltage bias is translated from kinetic energy to heat energy. Before the resistor the resistance is neglible so the drift velocity will be high, and collsions will be minimal. Even so as the charges move from the positve terminal the Electric field will be strong and we will be losing the potential energy as we travel in the direction of the field. With this so why dosent potential drop as we move in the direction of the field? Is the energy associated with the charge essentially translated from potential to kinetic energy, where very little of this kinetic energy is translated to heat energy, and we assume the total potential is associated with the total energy the charge has at this point (KE + PE)?

I am really looking for an answer to my question. It would be much appreciated if we address the core question I asking instead of side discussions! After the initial answer, I encourage side discussions if wanted!


texts: How can I best fake an (AM radio) antenna signal?

texts:
I have an old (~late 1920s) AM radio that I'm currently working on. As I don't want to modify any of the internals significantly, it would be nice to have a way to fake antenna input. It's not entirely clear to me how to safely do this, however (it has been a number of years since I dealt with anything involving RF).

Would it be sufficient/safe to just have a very low voltage (relative to a common ground) AM signal through the antenna input? Or would this be entirely wrong, and damage the radio? If this would work, what order of magnitude would one expect the required voltage to be?


texts: will a circuit breaker designed for 230VAC work for 12VDC?

texts:
Will a standard home automatic circuit breaker, designed and sold as to work on 230V AC (alternating current), and for example 16A, or 25A etc, will it work (break the circuit if it exceeds the rated amperage) on 12V direct current (DC)?

If not, are there any automatic circuit breakers for over-current protection, which work on DC? I mean besides fuses which blow, I want the thing to be reusable with a click, not one-time-use.


texts: Why is my instrumentation amplifier railing with no inputs at its terminals and proper supply voltage?

texts:
This question is so stupid it hurts.

http://www.ti.com/lit/ds/symlink/ina122.pdf

I am using an INA-122 instrumentation amplifier. I am supplying power from an Arduino, either 3.3V or 5.0V at my choosing. Without using any resistor for gain, and without applying any voltage to the +/- terminals I am consistently getting outputs of ~3.4V and ~5.1V, respectively. This happens even when i dont connect anything to the positive and negative input terminals. These are within range of INA's specifications. When I connect my load (0.1mV differences between the positive & negative terminal, as well as a right-leg-driver going to reference), I still am getting maxed-out outputs.

What am I missing here? I need to admit that I am a huge amateur.

I am following this DIY EEG guide

http://www.instructables.com/id/DIY-EEG-and-ECG-Circuit/step2/Complete-Design/

This is the general schematic, although the instrumentation and op amps I'm using differ slightly

I have tried two of them, same result. I think the Arduino,GND circuit is single supply


texts:
I'm working on an XScale PXA270 with NOR Flash on Chip select 0.

Due to the obsolescence of the previous flash, my company changed it for an AMD/Spansion compatible MX29GL128.

I'm trying to write on it using Lauterbach JTAG.

Here is my script :     https://pastebin.com/jcjsbwE3

; reset the FLASH declaration
FLASH.CFI 0x00000000 L
; declare FLASH sectors via
; CFI query
;FLASH.CHANGEtype ALL AM29F100
; change type to AM29F100 to use "word wise" mode
FLASH.UNLOCK ALL
; unlock FLASH if required
FLASH.ReProgram ALL
; enable the FLASH for programming
;Data.LOAD.auto /home/lai/devel/uboot-2017-01/u-boot.bin
Data.LOAD.binary /tftpboot/u-boot-rioms-pxa270.bin D:0x00000000--0x1FFFF
; load the programming file
FLASH.ReProgram off
; program the FLASH and disable
; the FLASH programming

But I get an error.

  Flash programming error around address SD:0x7C.

On this picture, you can see the commands on the bus and the error:

Have you any ideas? I've been stuck on it for many days.


texts:
I've built a run of simple boards like the one shown below to control LEDs in automobiles. The boards have twenty of the NX3008 mosfets in an open-drain configuration as shown, which are controlled by a PIC24 with PWM. I kept the circuit simple in order to keep the chip count down and therefore the cost low, but I am finding that a number of my customers are damaging the mosfets either by shorting them to +12 momentarily, overloading them, or (maybe) damaging them with ESD. I myself have not handled them very carefully at all and have yet to damage one with ESD, however, this is happening often enough that I'm skeptical that the other two causes of failure are the only ones. Other than that, the devices have been very reliable once installed correctly on the vehicle.

Anyway, I'm looking for suggestions on how to prevent or mitigate damage to these mosfets.

I considered adding a ~5-ohm source resistor, however, this would not only almost double my chip count but would potentially dissipate a lot of heat on this little board when all 20 going at once. Is there maybe a better part to use?

simulate this circuit – Schematic created using CircuitLab


texts: Is it safe to use nSleep pin of DRV883x Motor driver, as a PWM control?

texts:
DRV883x H-Bridge drivers implement 3 pins to control driver's behavior; IN1/IN2 for DRV8837 and EN/PH for DRV8838. except for these 3 pins, they are pin to pin compatible:

For a simple, dual H-Bridge motor driver module, I wanted to be able to use both chips in my design according to availability. sure I would change the code for specific pin controls.
For the DRV8837, I need 4 PWM output from MCU for dual H-bridges; each one connected to one of INx pins of DRV8837s. despite being a little demanding, it is fine (I can use some logic gates to reduce PWM pin counts).
But for the DRV8838, it seems the PWM control is not possible at all; the PH pin reverses the bridge and PWM on EN pin, brakes.
The Question:
Can I use the nSleep pin for a reasonable low frequency PWM control?
If possible, the design would be intact for both chips as the nSleep pin have the same behavior (coast) for both chips. also there would be just one PWM pin per driver and the other control pins would be just simple GPIO.


texts: If I used an everyday 9v alkaline battery to power a 6v DC motor, would it work?

texts: I am totally new to electronics and don't know much but am trying to create a project that uses a 29rpm 6v DC motor. I was wondering if I were to use a higher voltage battery ( a 9v battery) would it be able to power the lower voltage motor?


texts:
I needed a SPDT relay with 240Vac so I bought this relay from Maplin http://www.maplin.co.uk/p/15a240vac-spdt-miniature-relay-n07aw

But I am heaving problem to wire this relay because it has 8 pins not like other SPDT relays 5, I couldn't find any documentation about this relay. The only thing that I have is this diagram which is printed in relay . Would also be helpful if someone can confirm that I need to power this relay with 12V, I will use also Arduino to control this relay


texts: LED when soldered doesn't work, but when removed it works

texts:
I have this kit https://www.amazon.ca/gp/product/B07GRYNV6F/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

soldered everything correctly (checked multiple times, the right element in the right place, the polarities etc)

One LED though acts strangely. When I solder it (correct polarity) it doesn't work. The multi meter connected directly to the two pins (not the solder points, directly to the LED legs) shows a dead LED. However when removed from the circuit, i can confirm with multi-meter that it is good and it lights up.

It is probably a very basic think that i am missing, but i am unable to figure it out. and sorry if I am wasting your time.

any hints on what I could verify or can anyone think of an explanation of why is this happening.

appreciate in advance any help
thanks


texts: Supply microcontroller and solenoid with the same battery at different voltage levels

texts:
I'm working with a microcontroller which its supply voltage range is 1.8V to 3.6V

I want to connect a solenoid to this mcu (this solenoid will be activated occasionally).

Current–voltage characteristic of the solenoid:

  Input voltage: DC6V

  Direct current: 0.35~0.476 A

So, my idea is to connect a 3.6V battery to the mcu and use a DC DC Converter to supply the solenoid.

But the problem is that I cannot find any 3.6V to 6V DC DC converter.

Any help would be really appreciated.


texts: interface component for screwing to make electric contact

texts: Is there a component that allows you to stack two PCB on top of each other and screw them together to make electric contact? Thanks!


texts: Can this ESP wifi board's firmware be rewritten?

texts:
I'm new to all this node mcu thing. I'm searching for relay shields because they're ready and well soldered, so I can put them into my light switches with no effort.

I've found this pack which already comes with the ESP and a custom firmware. I don't want to trust a strange firmware, I want to upload my own and play with it.

Can this ESP8266 ESP-01S's firmware be rewritten, and if so, which equipment I'll need?

link for the product


texts:
I have a simple circuit using an NPN as a switch using the BCW71 (https://www.mouser.es/datasheet/2/308/BCW71-D-1802620.pdf), as seen in the following picture:

My issue is that when I put 3V3 at the base, I get 2.6V at the emitter, so I have a voltage drop of almost 13V at the transistor. When I put 0V at the base the emitter is zero. Am I missing something?
Edit: R23 goes to the gate of an N-channel MOSFET.


texts:
I have a LCD Monitor that has a 2.1mm Right Angle DC Power Plug which has gotten loose over time. It frequently comes off and I needed to tap it in, but now even that does not seem to work. I'm wondering if I can replace just the plug at the end. I'm looking at various plugs e.g.

  Amazon - Philmore Right Angle DC Power Plug w/ 6' Cable - 2.1mm I.D.
  5.5mm O.D. : TC210

This seems to be very similar to what I'm looking for, but I cannot figure out if it has grounding. The power adapter to my LCD Monitor is three pronged, implying grounding, but I cannot say if the actual plug has grounding just from looking at it. I can also see DC Power Jacks that have grounding e.g.

  StackExchange - what is the name for this DC connector?

Which brings me to my question:

  Are Coaxial DC Power Plugs with Grounding available?

If there are none, would there be any issue with using a non-grounded plug like the one mentioned earlier for my LCD Monitor.

Edit: Additional Information

I did not think this was necessary, but since it was raised in the expected answer I decided to add it here.
I have two identical monitors (same brand and model number) which were purchased at the same time. One of them had a slightly defective power plug, but I did not complain about it because it worked for most part.

Now 5 years later, this plug does not work with either monitor. However, the plug of the other monitor can power up the first monitor just fine. Since the power jack on the first monitor has been worn out by twisting and turning this defective plug, it takes a small tap/twist for the working power plug to power up. (In it's original monitor it works on the first try.) So I'm certain the issue is with the power plug not on the monitor jack.


texts: Clamper circuit, how to apply kirchhoff when the diode is turned around?

texts:
in this clamper circuit it's easy for me to determine the output waveform:

This is how I do it:

In the positive half cycle, the diode is forward biased with a drop of 0.7 V, so the positive half output is limited to 0.7 V

In the negative half cycle, the diode is reverse biased, and the capacitor has a voltage of 3.3 V, so the negative half output, by applying Kirchhoff:

-Vout - Vin - Vc = 0
Vout = -Vin - Vc = -4-3.3 = -7.3 V

So the output waveform has a positive peak of 0.7 V and negative peak of -7.3 V

But when he asks me to turn the diode around, like this:

I face problems when I apply Kirchhoff, this is how I do it:

In the first positive half cycle, the diode is reverse biased and the capacitor has a voltage of 3.3 V, applying Kirchhoff:

-Vout + Vin - Vc = 0
Vout = Vin - Vc = 4-3.3 = 0.7 V

In the negative half cycle, the diode is forward biased, so it has a drop of 0.7 V, so the output is limited to -0.7 V

I end up with a positive peak of 0.7 V and a negative peak of - 0.7 V , but this should be wrong, the right answer should be the exact same as the first circuit but with different signs, I don't understand how though, can someone let me know, thank you.