texts:
This chip cannot run the Hall sensors on each power on. The chip can operate with microcontroller each time, the register 'who-am-i' returns 0x3d, configuration registers are able to read and write. Sometimes the chip returns zeros as magnetic values, only hard reset solves this problem. This happens about 1 time of 10.
This is oscilligraph chart on pin 4 (0.1 uF capacitor) when the Hall sensors works normally:

This is oscillograph chart on pin 4 when the Hall sensors doesn't work:

What should I do?

UPD
Schematic diagram:

Board fragment:

do you mean 1 power-on out of 10

yes

do you mean only a power-cycle solves this

When I power off the device and then power on, the problem disappears.

has the design ever worked without this problem in the past?
Do you have multiple sets of this LIS3MDL hardware or only one?

The design ever has the same problem. I have 16 sets. This problem appears on each board.

What diagnosis have you done so far, with what results?

I detected the difference between working and non-working state as shown on oscilloscope chart. There are no other visible faults.

UPD2

the datasheet suggests 1µF paralleled with 0.1µF on the Vdd pin; you have only the latter

The power supply circuit has 10 uF capacitor:

Is it nessesary to add 1 uF capacitor?


texts:
How can I find polarization of an electric field as shown below?
$$\vec E (0,0,0) = \vec a_x E_{0x}+\vec a_y + 2j \vec a_z \dfrac{V}{m} $$
The propagation of the wave is as shown below.
$$ \vec a_n = \dfrac{1}{2} \vec a_x - \dfrac{\sqrt 3}{2} \vec a _y $$
To determine the polarization of the wave, first I obtained the phasor notation.
$$ \vec E (x,y,z) = \dfrac{1}{2} \vec a_x e^{\dfrac{1}{2} \vec a_x - \dfrac{\sqrt 3}{2} \vec a _y} +  \vec a_y e^{\dfrac{1}{2} \vec a_x - \dfrac{\sqrt 3}{2} \vec a _y} + 2j \vec a_z e^{\dfrac{1}{2} \vec a_x - \dfrac{\sqrt 3}{2} \vec a _y}$$
Then turn the notation to cosine representation.
$$ \vec E (x,y,z) = \dfrac{1}{2} \vec a_x cos (wt-k(\dfrac{1}{2} \vec a_x - \dfrac{\sqrt 3}{2})+ \vec a_y cos (wt-k(\dfrac{1}{2} \vec a_x - \dfrac{\sqrt 3}{2})+2j\vec a_z cos (wt-k(\dfrac{1}{2} \vec a_x - \dfrac{\sqrt 3}{2}))$$
By making $$wt = 0, \pi /4, \pi/2, \pi $$
we should be able to sense the polarization of the wave. But since the has three position vectors, I couldn't get a proper understanding.
How can I determine the polarization?


texts: How can I send multiple values from Processing to Arduino via Serial library?

texts:
I've done a basic test sending a single int value to Arduino from Processing via the Processing Serial library and all's fine. I would like to send multiple int values, but not entirely sure what's the best way to that.

Acoording to the docs Serial.write

  writes bytes, chars, ints, bytes[], Strings to the serial port

so one option would be to send a string I can split and get the values:

arduino.write(intValue1+","+intValue2);

but I'm not sure how I would read the data convert when I receive it in Arduino.

Another thing that comes into mind is to use a byte[] since I'm sending multiple values, but I haven't worked with bytes much, so any advice on how pack/unpack two into a byte[] and back would be really handy.

Thanks!


texts: Why is the angle units of phasor form in degrees and not in radians?

texts:
The question below:

The correct answer is "B."
Why isn't also "A" a correct answer?
I tried the numbers in my Classwiz calculator and both gave the same rectangular answer.
Here the angle unit used is degree:

Here the angle unit is radian:

Of course if I put the angle as π/3 while using degrees as a reference unit it would give a wrong answer (as shown below) just like putting 60 and using radians to be the reference angle unit.

why isn't option A a correct answer although in option A it says rad?


texts: What's the easiest way to prevent a voltage input getting higher than a fixed value?

texts: I just got a DC-DC step-up converter for my laptop, and I want to make double sure in case it malfunctions it will never affect my laptop. I am looking for an extra security device to prevent the voltage from getting higher than 19v. What would be the easiest and most efficient way to do that?


texts: Is C-SAM test needed for new baking oven for IC?

texts: I bought a conventional oven for baking ICs. Do i need to perform C-SAM test on the units after baking? I think units will not be affected if you will use the required baking temperature and time right?


texts: Is DC modulated with a sine wave actually AC?

texts: So we have a DC level that, for example, varies between 0VDC and 10VDC in sinusoidal fashion. Is that classified as alternating current even though it does not go negative?


texts: What type of circuit or component is used to sample RF power?

texts:
I'm building a 2-stage RF power amplifier and I would like to measure the RF power at each stage and report it to a microcontroller on the board:
  17dBm -> [amp1] -> 36dBm -> [amp2] -> 50dBm
                       |                 |
                       +-Probe1 to MCU   +- Probe2 to MCU

What component or circuit would you use to sample RMS power in the 150-500MHz range with minimal loss?  The output is 50-Ohm impedance, but the middle stage (Probe1) is a complex match.


texts:
I wonder if someone could help me. A few days ago, my brother gave me all of his electronics, seeing that he doesn't need it anymore. I'm keen to learn electronics in depth and have basic knowledge such as resistor formulations, etc.

Scratching around in the stuff, I found something that looks like a very small xray of a PCB. After explaining to me what it was, he encouraged me to build it. I tried googling around about how to make it, but my search came back unsuccessful. Can't ask my brother how to do it, because he's out of the country on work.

So here's the question: How do I make the rails on the PCB? Everyone mentions using acid - what do I use and where would I typically find it?


texts: How to connect flyback diodes on a h-bridge

texts:
I'm using a SN754410NE h-bridge to drive two DC motors (4.5V each) with Arduino. After testing the circuit and the code, I made a standalone Arduino on a perma-proto breadboard.

My problem is that while the motors are running I see that led13 (the red led on the schematic) flashes periodically, while it's not supposed to (my code doesn't use that pin at all). After a while my atmel328 chip is kind of "erased" and in order to make my robot work again, I have to reprogram the chip.

So after looking around I found out that my h-bridge doesn't come with protection/flyback diodes (correct me if I'm wrong) and I need to add them myself. I have some 1N40001 diodes but am not sure how and where to connect them. Should I connect parallel to the motor leads? And if so, what the polarity should be given that the polarity can change (the motors run in both directions). Alternatively, should I connect the diodes serially to the wires connecting the Arduino digital pins to the driver input pins on the h-bridge?


texts:
Perhaps my understanding of how magnets work is off, but would it possible to play some waveforms into the positive and negative leads of a DC fan (think motherboard fan) and get a coherent sound? I understand if this were possible, that you'd need amplified sound to be driving into the fan to get a sound due to design constraints, equipment I don't have so I can't test it.

Crazier... If it was possible to play sounds from the fan, would it be possible to attempt this with the fan spinning?


texts: Can I connect batteries of different ampere hours in series?

texts:
I have 4 12V 20 Ah, 2 12V 7 Ah, and 2 12V 8.5 Ah SLA batteries. If I were to put them in series to get 24V and then parallel to get 55.5 Ah, would it be safe and would it work? Also are VRLA and SLA batteries the same thing? As the 8.5 Ah batteries say VRLA on them while the rest are say SLA. I plan on putting them in a CyberPower CP1500PFCLCD UPS.

Okay then, what if I just used the SLA batteries and not the VRLA batteries? Or should I just stick with the 4 20Ah batteries?
Okay, seems like this is a bad idea, I'll just stick to the default batteries inside of it. I'd rather have a house to come back home to than an extra 30-45m of being able to use my computer in a thunderstorm.


texts: When a diode does not conduct what happens to the current?

texts:
simulate this circuit – Schematic created using CircuitLab

Since the voltage at node(A) is 30V, the diode(D1) does not conduct because the voltage at the anode is 20V. What about the current that has been divide due to the parallel branches? At point B is there current = (V/R)/2 (equal currents between branches since both resistance are the same)?

If so, the load would have lower current input?


texts: How to generate 1 MHz pulses of +10/-30V?

texts:
I want to generate 1 megahertz square wave pulses between +10V and -30V, supplying 20mA with a variable duty cycle. What is the recommended way to do this given the inconvenient voltages and moderately high frequency?

I can easily generate the 1 MHz signal so I just need a way to boost the voltage. Op amps that go beyond +/-15V with a high slew rate seem uncommon. Would two mosfets in a push-pull configuration work better?

The closest answer I found was this but my voltage and frequency are higher.


texts: Is memory bandwidth advertised for DRAM (like 12800 MB/s for PC-12800) ever achievable?

texts: Memory bandwidth for DRAM like DDR3-1600 / PC-12800 is a function (product) of memory frequency (1600 MHz) and memory bus characteristics (width and number of channels). But memory also has timings (for example, 11-11-11, measured in cycles). So is it true that the value of memory bandwidth (12800 MB/s) is unreachable unless timings for that memory equal 0 (zero), that is unreal?


texts: Power on reset and watchdog signal combination question

texts:
I'm working with the i.MX RT1050 processors and designing a POR circuit.

I found the following circuit in the reference design but I don't understand how it's meant to work.

The UM805RE is a voltage supervisor that generates a reset when VCC goes low. It also has a Manual Reset (MR) that triggers when it is brought low.

What I don't understand is how the POR_BUTTON and WDOG_B signals are combined. I simulated it, and the POR_BUTTON signal gets through to trigger the MR.

But the WDOG_B signal is blocked by a capacitor, and won't trigger

Can anyone help explain this, is it a mistake in the reference design?

Thanks


texts: How to deduce the current function from the graph?

texts:
I want to express the current function based on the next graph

So using the slope and the coordinates in the third interval the current will be
\$i(t)=\begin{cases}
0\,A & 0\,s<t<t_{1}\,s\\
7\,A & t_{1}\\
y-7=\frac{8-7}{t_{2}-t{1}}(x-t_{1}) A& t_{1}<t<t_{2}\\
8\,A & t_{2}\\
\\
\end{cases}\$

This is the right approach?
I intend to use the expression to calculate the average and rms current.
Also if can point me more problems like this.


texts: How to get a .bin program on the STM32F4 discovery board?

texts:
Simple question. I want to program this board: http://www.st.com/web/catalog/tools/FM116/SC959/SS1532/PF252419

On my computer I've generated a .bin file using this library: https://github.com/emusan/stm32f4-template

How do I get said .bin file on the MCU program flash memory? What wires do I need? New to this process. For background, I am using Windows 7.


texts: how might i make a mouse who's L and R buttons flip depending on what side of the keyboard it's on?

texts:
I was thinking trying to make a little prototype of a wireless mouse that was left-handed or right-handed depending on which side of the keyboard it's on.

How might I modify a mouse so that the signals from the button clicks cross if they are on oppisite sides of the keyboard?

I'm thinking some kind of small component that knows if it's with a keyboards-width-distance of something attached to one side of the keyboard could toggle whatever mechanism does the reversing.

Is this maybe doable?


texts: Query: why a 4-pin DIN plug on a 5 VDC 10 A supply?

texts: My new 5 VDC 50 W PSU has a 4-pin DIN output plug. The output diagram on the PSU lists two pins as (-), and two as (+). The voltage between any +/- pair is identical (5.13 V), so why the need for two pairs of pins? Why not a two-pin connector? (And can I simply connect the two '-' outputs together, and the two '+' outputs?) Is this just a case of having a standard connector, and the option of having two separate 5 A circuits? Seems arbitrary.


texts:
I have 2 x AD9833s programmable waveform generators running off the same SPI bus.
Generator A is on channel 1 (yellow in the picture below) and is a sine wave set at 1 kHz.

Generator B is on channel 2 (blue in the picture below) and is a sine wave set at 2 kHz.

The outputs are as expected if I just probe each output individually but when I probe both at the same time I get...

Can someone explain what is happening here? Is there some scope-voodoo I'm unaware of?
SOLVED: I had the probe leads connected incorrectly, I had the scope grounds connected to the generator signal out & vice-versa.


texts: My air compressor electric motor is rated at 3hp/230v single phase It has a capacitor (black can)

texts: My air compressor motor is a 3hp/230v single phase. The plug is a 3-prong marked 250v. I've checked the L1 lead (black) at the motor proper and show continuity (ohmmeter) to the L2 lead (white). I wired the receptacle using a 20 amp breaker; running the white and black leads of 12/2 wire from the breaker to the L1 and L2 connections on the outlet with the ground (copper) going to the ground lug on the outlet. The motor does nothing wired this way. Move the white lead at the breaker to the ground bar in the panel and the motor will run but can't handle any load whatsoever which I understand is the norm for a 230v motor being run on 120v. What am I doing wrong?


texts: What is the relevancy between the actual full load current value (test result) and the supposedly corresponding values from industry standards?

texts:
I work on evaluating a motor problem. If I am given an actual current at 100% full load, how does an industry standard value become relevant?

I have an example to illustrate the point I am trying to make:

If I will buy a motor, one needs to evaluate two groups of things:

1) The motors ratings and whether or not they fit my need.
2) If the already existing system   are or are not compatible in all aspects.

For the first group, let us just say that I tested the motor. It is perfect. It outputs the required torque.

For the second group, let us say that i had to make sure that my cables and protection devices are capable of handling the worst case circumstances.

Now, while I will have an advantage of using current values from industry standards in order to make sure that my second group evaluations are perfect, I do not see any relevancy between the actual current from the full load test and the theoretical full load current from the industry standards?

So, my questions:

1- What is the relevancy between the actual full load current (test result) and supposedly corresponding values from industry standards?

2- What is the advantage of this relevancy?


texts: I am currently working with 74HC4046 IC. I want to know (calculate) what is the VCO sensitivity (in Hz/V) when Phase Detector 1 is used. I have the datasheet but I am not sure how to make the calculation. Any ideas?


texts: Maximum operating temperatures of different lead acid batteries

texts:
What are the (generally) safe maximum operating temperatures of various lead acid batteries such as wet cells, sealed lead acid, glass mat?

I'm looking for a battery that can withstand around 60 degrees C at a low discharge rate (recharge would be at room temperature). If lead acid batteries are not appropriate, what would be a better alternative?

operating-temperature


texts: Is it really necessary to unplug devices from the wall before connecting HDMI?

texts:
I was under the impression that HDMI was built to be hot-swap ready... like a USB device. I was told recently that unplugging HDMI while devices were powered on was risky and could actually cause hardware damage. Sure enough... my PS3 manual states that you must turn off and completely unplug both the TV and PS3 before connecting/disconnecting the HDMI cable. Same instructions in my digital camera's manual. Is this really necessary to completely unplug devices from the mains, or are they just covering their butts? Turning the power off is easy enough, but it would be a huge hassle to unplug my wall mounted TV just to connect my camera for a slideshow...

Any thoughts?


texts: Where do I get custom packaging for my complete .NET Gadgeteer project?

texts:
I'm considering using a GHI system-on-module (and related accessories) for a .NET Micro project.

I want to have a high quality, waterproof case for my design, but I'm unsure where to go on my next phase.

How do circuit designers generally approach creating such a prototype?

I could use a 3D printer for the initial rough draft, but I would like to have something that looks/feels a bit more professional in the initial round.


texts: Intercom device, door-opener and door-bell

texts:
I got a Bticino intercom system (non-wireless). I did some restoration in my hallway and disconnected the device. Unfortunately I do not remember how it was wired before I set it up afterwards. Now we got a new common door, so I dunno if it is connected to the intercom system.

I've tried to find a manual of this, but this is an older system and I can't seem to find anything related to it. The wires are differently colored, and ive tried all sorts of connections.

The thing is, I should be able to open the common door for visitors with this unit. And it is also a door-bell (I dunno where the speaker is however) so visitors can ring from outside.

Im not sure where these wires should go, and I also do not know how to be able to open the outer door from this unit. Also on the bottom right of the picture there is a switch.


texts:
I have bought a 16 x 2 LCD which I want to interface to a ATMEGA 324 microcontroller.
The problem is that the vendor didn't give me a good enough datasheet.
It does not contain any information regarding the initializing of the LCD.

At the product description it said that the controller is HD44780. I followed the initializing sequence in the datasheet, but all I get is one line of white full rectangles.
I followed other initializing sequences, but all that I got were 2 lines of white full rectangles or a full line + a line with smaller rectangles.

Do you have any idea where I could find the correct initializing sequence?
The LCD looks like this:

And on the back it says "1602A" and "QAPASS".

I will post later the sequences which I have tried to use.


texts: How to perform a synchronous output on the Arduino?

texts:
I have a device I'm trying to control with the Arduino.

It works like this.

Arduino sets and holds 'ready line' to 5V high.
Device sees ready line high and sends 16 clock pulses for two bytes of messages to receive.
On each clock pulse the Arduino sets the data output to whatever the bit should be (0 or 1)
When the two bytes have been sent, the 'ready line' is set back to 0v low.

The problem I have is getting the Arduino to sync to the clock pulses. Currently I have an if-statement that sets the data line if it sees the clock line high, but this does not seem to work. I think I should be looking for the rising edge instead.

How can I sync these two devices properly?


texts: Identify valid FPGA configuration image in serial flash device?

texts:
How can I know if there's valid FPGA configuration image in the specific location of the serial configuration device before I perform reconfiguration and experience successful or faulty attempt?

Looking at what is being written into the flash as an image I have no idea if there's any header to identify or how to calculate and compare checksum to ensure data is not a garbage, but some valid image.

I know images can be compressed or uncompressed, but I guess there must be some simple way to identify if the code is valid. Not much info is available online. I would actually not be surprised if this part of IP is not licensed for wide community, or if it is very dependent on the actual FPGA device being used (thus no standard for it - even from the same vendor).

Design can read from the serial flash chip, thus if the detection algorithm is known identification is just a matter for coding.


texts: What is a cheap technology to allow multiple devices to know each other when close in proximity?

texts:
I want to make some objects that will know when they are, let's say, 3 feet(or less) from each other.

They need to also know the identification of the objects close to them.

For example. If object Ball is in presence of a Cube, they would both be 'unhappy'. But if a Ball is in the presence of another Ball. They would both be 'happy'.

Summing up...I'm looking for cheap ways to have objects:
(1) know when others are around
(2) know their unique ID (which would probably require some sort of broadcasting of IDs by each device)


texts: What is the IEC standard number for this plug?

texts: I need the specific IEC standard number for a power plug/socket used in a laptop. See the photo below. I need to know the laptop-side plug (the lower plug in the photo). Thanks. This plug is used in Lenovo laptop power supplies, and others.


texts: Schottky diode as a flyback diode with PWM?

texts:
I found similar posts but need little more hand-holding - no engineering background. I tried to document the circuit to my best ability but i recognize its far from perfect:

I was reading these two posts: How to use a flyback diode on a +/-12V motor and Do I need a Schottky diode as a flyback diode with PWM @ 30khz?

Question 1: The motor is reversing and it requires two Schottky diodes around the motor (since polarity changes). Can I just put one diode right outside the PWM controller before the reversing relay where polarity doesn't change?

Question 2: In either scenario, can you recommend specific diode to buy? it's 24v 60amp (max for both controller and the motor).

Question 3: the reversing relay activating coil is 12v and its turned on by another relay that is linked to Arduino (operating at 5v). When turning off the bigger relay, i get lots of "feedback" that messes up the rest of the 12v and 5v electronics (DACs, sensors, etc.). So, was also thinking about putting a diode across the reversing (larger) relay coil. Does it make sense? If yes, what is the specific diode I should buy?

CLARIFICATIONS:

the PWM controller doesn't have it's own reversing function. Here is the actual link

Regarding the question #3 - I left some things out from the diagram but the relay has separate supply for powering the coils (arduino just sends signal) and it works (I already have it set up). Otherwise, yes, it would be too much for Arduino to handle. I am still getting feedback on the entire 5v circuit and, based on your suggestion, putting in diode across the larger relay coils makes sense - any recommendation on specific diode will be appreciated.

the main question (#1 and #2) - your analogue about the train helped and I am guessing I don't need a diode after all:

the PWM is controlled by software and it always accelerates and decelerates very slowly (even if the throttle gets pulled hard moving 1000lbs cart). The reversing relay never activates unless the motors are at full stop. So, I am guessing diodes are not needed?


texts: How can I use a square wave to interleave 2 LEDs with an arduino?

texts:
I have a PCB that drives a camera. I want to flash 2 LEDs in time with the camera's framerate using an Arduino.
After some examination I found a CLK pin on the PCB that I think might correspond to the framerate and it outputs a 32.76KHz square wave with a voltage of 3.5V Pk-Pk. I was thinking of a pseudocode that looks something like this:
%Initialize by finding a place in the signal to start (at the edge of the square wave)

%Define variables

%current state of the Square wave
SquareWaveState = 0
%previous state of the Square wave
lastSquarewaveState = 0

%Read in signal
Squarewave = digitalRead(SquarewavePin);

%Find Edge
if SquareWaveState (Does not equal) lastSquarewaveState
if SquareWaveState == HIGH

%From this point in the signal, we can time the circuit according to the square wave

Loop(
Turn on LED1
delay(15.262515us) (time the square wave is 'on')
Turn off LED1
delay(15.262515us) (time the square wave is 'off')
Turn on LED2
delay(15.262515us) (time the square wave is 'on')
Turn off LED2
delay(15.262515us) (time the square wave is 'off')
)

I have several problems though. I am new to Arduino (and electronics in general). I have high quality LEDs but the timing is extremely fast and I know LEDs generally need time to turn on and off. Also the psuedocode is not very robust as it relies on hard coding timing directly. I would test it out but due to COVID our lab is taking a break. Does anyone have any suggestions on making this code more robust? Does it make sense that the CLK pin would drive the frames of a camera?


texts: Need advice regarding a regulated HV DC power supply for Magnetron

texts:
I need a DC 4.2Kv 300ma power supply, and am looking for advice.

I'm currently using a the guts of a microwave oven (transformer/diode/capacitor) to power a magnetron for a physics experiment.  The transformer outputs 2.1kv into a diode/capacitor voltage doubler to produces a 50% duty cycle 4.2KV potential at 60hz.  The resulting signal from the magnetron is noisier than an LA freeway at rush hour.

According to this paper changing the unit to a regulated HV power supply, controlling the filament heater separately, and reducing the filament current after it reaches operating conditions should allow it to phase lock onto an external signal and operate as a low noise amplifier.

For the HV side, my first instinct was to buy a commercial supply.  I priced them, and after regaining consciousness thought I should ask here.

Question:  Is there a way to smooth out the power from my existing supply or another inexpensive alternative I should consider?

Thanks in advance.

(Amateur: yes. Kid/teenager: no. Experience in electronics: Kit-building. Follows safety procedures/common sense: yes...Safety advice is always appreciated.)

Added additional details on safety and end use to comments.


texts: Transistor Logic Gates in One Breadboard

texts: How can I make a combination of the 7 Transistor Logic Gate and putting those gate in only one breadboard.? I've seen the combination on this Topic: How to combine multiple transistor logic gates without gigantic voltage-drop? I am very much interested to do try on how it was built in only one breadboard... strong text


texts:
Alright, I know I am going to get a lot of flak for this, but let me reassure you that I have already spent the last few days reading on Google while going back and forth from the bench to test different things. I have taken numerous seated/structured classes on basic circuit design and basic electrical engineering courses, yet it seems every time I take a break and come back to the material in application, I can never seem to grasp the most basic concepts. The math of Ohms law is simple and makes perfect sense, but am I the only one that seems to still confuse things in application? Ok, enough setup (and please dont edit my question. I included that information for a reason...).

I am testing a new off the shelf switch mode power supply. I don't have all that much experience with them, in fact I just recently learned about their minimum current requirements. That's the problem I am trying to overcome.

This power supply requires a minimum load to turn on. Can you please help me determine the proper minimum dummy load to get the power supply to turn on and stabilize?

If the supply (RT-125D http://www.mouser.com/ds/2/260/RT-125-SPEC-806385.pdf) has a minimum current of .1A on V3 (12V rail), does that mean I can throw a 120 ohm resistor (R=V/I R=12v/.1A) across the terminals to get that minimum load? Also, that resistor should be rated for at least 1.2W but realistically, should probably be rated for quite a bit higher right? Maybe 2W - 4W? (P=V^2/R P= 12v^2/120ohms) Is my thought process right so far? That should be enough minimum load to at least get the supply to turn on right?

Side note: This supply may not always have a load in its final application which is why I need this dummy load. Or... I guess I need to find a supply with no minimum load requirement (which I understand does essentially the same thing I am trying to do here anyways, just inside the supply itself)

Any help here is greatly appreciated.

Thanks


texts: Basic Circuit Analysis using Kirchhoff and Ohm's Laws

texts:
So I'm in an introductory circuit analysis class where all we have learned so far are Kirchhoff's and Ohm's Law.  I am practicing how to solve these circuits, but for some reason I can't understand this example.  I keep getting 3 Amps for \$i_5\$, but it says the answer is 2 A? I end up getting an equation like this:

$$3i_5 + 7i_5 - 2i_5 = 24$$

$$8i_5 = 24$$

$$i_5 = 3\ \mathrm{(V/Ohm)} = 3\ \mathrm{Amps}$$


texts: Looking for a fully internal one-time switch

texts:
Edit/tl;dr: What are some alternatives to reed switches?

I'm looking for a switch that can be closed one-time that doesn't require any case penetration. The design is inside a water-proof enclosure. The switch goes between an 18V, 25Ah battery and some electronics. I'm obviously aware of reed switches, which seem like the perfect solution, but I'm concerned about reliability.

The application is a scientific instrument which is deployed in the ocean and is not serviceable. The switch is necessary because the device is in-transit/storage for sometimes more than 1 year. The device operates for approx. 2 years on this battery.

I've done a lot of searching on this topic. I'm convinced I just do not know the right terminology to get me to my goal. This post most widely breaches this subject with lots of great suggestions but no great solution.

What I really want is something like a fuse, only instead of opening when it 'blows' it would close. This can be a complex circuit or a simple device, the only requirements are low power consumption(10's of uA or less) and no case penetration.


texts: How to measure power factor cos phi with an Arduino?

texts:
according to How does one measure the power factor? I can measure the power factor (cos phi) by comparing the zero point crossing of Voltage and Current. This is clear.

The problem I have is what if I can't tell exactly when the zero crossing is? My idea is to measure the cos phi with an arduino using a very simple circuit.

Basically I want to use Resistors to break down the voltage to +- 5, then use a diode to have only the positive waves. With this, I can sample the voltage using the analog input of the Arduino, let's say at least 2 faster than 50 Hz. The arduino nano for example has a clock speed of 16 MHz :-) (Nyqvist).

Now, with the current I plan to do the same. Take a cheap linear current transformer and convert to voltage using resistor, so I will get only + 5V max.

I will calculate resistors and transformers so that for the max V and A I will get the range I need, and I can also secure my Arduino with over voltage security.

I don't need to measure U and A exactly. I don't need this values with precision, that's why the usage of cheap elements and simple approach might be enough.

What I need is to calculate the phase. Please take a look at the picture:

Let's asume
 1. I can measure Current and Voltage as only positive waves from 0 to 5V max
 2. I sample fast enough
 3. I can detect the point where they go from zero to some value (I will make an error here as well...)
 4. There is some error on the measurement (magnitude)
 5. I can calculate dt between V and A. With it, I can calculate cos phi

My question is: is this possible/ feasible? Is the error I make in 3 big enough to make this cos phi measurement impractical? How can I calculate this error?

Thanks a lot


texts:
I want to create a DC-chopper to drive a motor. I found the following schematic online:

However i don't understand how the MOSFETs are driven. On top there is a P-channel MOSFET with source connected to Vcc, between 48V and 60V in the case of this example. However, according to the datasheet of this MOSFET, Vgs is -20V max. Since source is at 60V when the battery is full, the gate voltage must be above 40V. But the MOSFET driver is fed at 15V, and according to its datasheet the output voltage will be (almost) the same as the feeding voltage. So, Vgs is -45V, well above the rated Vgs. But, according to the video, the circuit works just fine.
Another question: doesn't the gate have to be at 60V to conduct and below around 56V to stop conducting? According to the schematic I think the gate voltage is being switched between 0V and 15V, so even if the MOSFET would be able to handle this, it should be powered off all the time? What am I missing?

Links:

P-channel MOSFET datasheet: https://www.infineon.com/dgdl/irf5305pbf.pdf?fileId=5546d462533600a4015355e370101993

MOSFET Driver: https://www.mouser.be/datasheet/2/268/21422c-73495.pdf

Instructable (with video): https://www.instructables.com/id/Make-Your-Own-Sensored-ESC/

Thanks!


texts:
Looking for some help with using an ESP32 (running Arduino IDE) to control a MOSFET. Currently, I have used the combo to control many things successfully by electronically "pressing buttons" by shorting the button contacts. I'm having trouble shorting two pins of a BMS (Battery Management System) for a LiPo battery that when shorted by a switch, enable the main battery output.

The BMS has 12v on one of the pins, and Ground on the other, and shorting them draws 0.04mA between them.

Problem is, when I enable the MOSFET with the ESP32, the BMS doesn't detect a short but does when physically shorted.

3.3V is present, and the MOSFET turns on after a few seconds of code, confirmed by continuity on a multimeter that collector/emitter are now connected.

How does the BMS know that the short is done with a MOSFET rather than a switch?

MOSFET is FQP30N06L
(Datasheet)

Also, is the GND on the emitter required seeing as there is a common ground between everything anyway?


texts:
So we're studying Schmitt triggers at university and we got these representations. Searched them on google for more info and got other representations. Now I'm confused. Can anyone help me with some info regarding the correctitude of these gates?

The representation we got for a positive hysteresis trigger:

This one was ok, found it the same online.

The representation for inverting trigger I found online:

Another representation I found online:

The representation we got on our course:

Now, with my logic, the one we got on class for inverting trigger is wrong. May anyone confirm or help understand it if I got it wrong? Also, how does it affect the signal output, is it the same as the positive hysteresis one with non inverting gate?


texts: How to use the on/off pin on a voltage regulator such as LM2574?

texts:
I was looking for a low quiescent voltage regulator to use in a low power atmega328 device and came across some regulators such as LM2574, LM2575 or MC33761, that has an on/off pin. How does one use that pin?

I'm a bit confused. The only way I could think of controlling this pin would be using the uC, but turning the regulator off wouldn't turn the uC off as well?

Edit: What happens when the regulator is turned off?


texts: Do I need curved RF tracks for a chip antenna?

texts:
I'm doing a PCB layout with a chip antenna on my board.

Is it important to make curved RF tracks from the MCU to the chip antenna or is it only important to have curved traces if I have RF connectors?


texts: About the combination of two signals with capacitors

texts:
Here is a link of an article I've been reading.
http://www.analoguehaven.com/moog/thereminblack/hotrod.pdf

In page 4 there is a circuit schematic. Notice there is a part called variable pitch oscillator and a part called fixed pitch oscillator. At the output of each of the two oscillators mentioned there is a capacitor. At page 6, the article states that:

C2 and C6 combine the pitch oscillator signals,
while D4, R23, R24, and C23 extract the difference
frequency. C2 and C6 also provide weak coupling
between the two pitch oscillators, which has the
effect of synchronizing the pitch oscillators when
their frequencies get very close together. This has
the desirable effect of providing a stable 'zero beat',
so that the instrument, once properly tuned, is silent
when the player steps away from it.

Question:

What I would like to understand is how the two output signals of the two oscillators are combined with the use of the capacitors C2 and C6.

Is it correct to say that the two capacitors work as modulator?
I'm saying this because the produced signal as you can see goes through a detector. Could you explain what exactly happens at the capacitors or how they combine the signal?

Thank you.


texts: How can I implement a proportional error control scheme with op amps?

texts:
So I have an IR distance sensor that I would like to use to keep two wheels (with DC motors) travelling parallel to the wall beside them.

I have these proportional error control formulae to keep the wheels straight;
$$
V_1 = V_{nom} + k_p (d - d_{nom})
$$
$$
V_2 = V_{nom} - k_p (d - d_{nom})
$$
but how should I set up the op-amp circuits for these formulae?


texts: Control relay (active low) without an transistor

texts:
I am using the Sain Smart 16-channel relay module. A relay is energized when the corresponding input pin is connected to the ground. I am using an Arduino to control the relay module using the GPIO pins. The suggested wiring was to use a NPN transistor to ground the input pin. However, I did this and it seems to work without any transistor. I basically connected the input pin to the ground with a 5k ohm resistor. When the GPIO is 0, the voltage is 0 and the relay closes and the light turns on. And when the GPIO pin pulls it to 5V,the relay opens and turns off the light.

Is that a good way to do this?


texts:
We have two PA's in a balanced config where the input RF signal comes into a directional coupler which acts like a splitter and then the output of the two PA's is combined by another directional coupler at the output end. We are using  Anaren X3C09P1 couplers. Please find attached block diagram of our PA setup.

We've been having EVM issues and upon inspection, we found that the 3.3V supply powering the PA's and other circuitry had a max current capacity of 700mA whereas the circuitry needed 1.035A. We replaced the regulator with a higher current version 1A as the 5V supply which supplies this regulator is maxed out at 1A.
We are still having issues despite being only 35mA short. Also, the regulator does not shutdown with the requirements of excessive current.
Also, We tried the circuit with only a single PA which drops the current requirement to 615mA but still got worse EVM.
EVM with single PA:
(20MHz = 5.8% at 24dBm; 10MHz = 6% at 24dBm; 5MHz = 10% at 24dBm)
EVM with two PA's:
(20MHz = 6.5% at 28dBm; 10MHz = 7% at 28dBm; 5MHz = 15% at 28dBm)
Expected EVM = 3.8~4.8% on all bandwidths.
Attached is the response from Skyworks on using single and dual PA's.

Any ideas of why a little less current leads to drastic changes in PA's EVM?


texts:
Which protocols are used in Europe? I'm more interested in "higher layer" protocols (e.g. light bulb control) than with the physical layer, but those will be welcome too.

Does the KNX standard have that "high layer" behaviour defined or it's just for physical layer (wires, electric power and RF)?


texts:
I am looking for design advice with a one-off Radar interface:

A RF video signal (Radar signal envelope) has to be sampled at 40 MHz
X datapoints in succession
triggered at 820 Hz
transfer of data after each acquisition sequence to a PC via USB

design constraints:

one-off design
minimal RF PCB design

My starting point would be:

a 40 MHz ADC -> requires 40 MHz clock & parallel datainterface to avoid high frequency circuits
SRAM to store at lease one acquisition sequence of X datapoints
microcontroller with USB interface

Questions/Problems:

Is there a better way to approach the problem?
What is the easiest way to control the acquisition sequence, i.e. to transfer the data from ADC to SRAM? This obviously cannot be controlled by the MCU and I would like to avoid having to learn FPGA programming. Are there any ready-made solutions?
What is the best way to get the data from the SRAM to the MCU? The parallel interface would require either a high pin-count or a serial converter that knows about SRAM read-cycles. Again: what is the best solution?

Many thanks.


texts: High power buck converter LiFePo4 charger

texts:
I’m planning to charge my 48V LifePo4 battery bank of some HV solar panels (Max 140V, MPPT @109V). Since I'm quite interested in the construction of power conversion electronics, I thought I would try out the DIY-route. It would be great if someone were to give me feedback on what the think about the converter I have come up with before I actually go about building it. How would you rate it between a 1 - will blow up immidiately to a 10 - has high chances of working as intended.
About the circuit:
I have more or less copied the average current control buck converter circuit as its described in the paper down below. I have added an PI voltage control loop to be able to limit the voltage though. I also added a safety relay which should isolate the battery from the output in case the mosfets fail as shorts or something else catastrophic happens. I have simulated the circuit in Falstad, although I'm not quite sure whether my results are realistic or whether im missing some vital parasitic effects. The end goal is to control the Max_Cur_Ctrl_PWMInput, Max_Volt_Ctrl_PWMInput with an Atmega 328 to do some rudimentary MPPT tracking (only input voltage)
I have considered implementing a reverse-flow shutdown using the current signal (since the hall current sensor is bidirectional). But then I gave the whole situation a thought: if the PV input drops out, the battery wont get charged anymore and its voltage will drop below the voltage setpoint. This means the circuit will ramp up the PWM duty cycle to 99%. This means the input cap will be charged to about the output voltage (60V max). At this voltage, the SMPS providing the 15V to the circuit will drop out (min 80V, tested), so the IR2104 will shut off the MOSFETs.
EDIT: I also wanted to ask whether the MC6004 is a good choice for my opamps. I chose it because its cheap and has R2RIO which I need for the triangle oscillator. UPDATE: After some simulation, the MCP6004 seems to be fine for the PI controllers, but completely inadequate for the triangle generator (too slow slewrate, too low GBWP). Im currently looking into relacing it with a TSH74 opamp.
Tools I have available:
Multimeter
LV Powersupply
Soldering iron
Old 2CH Analog Oscilloscope
Frequency Generator (Sq/Tri/Si) 20Hz - 2 MHz
EDIT: 13/05/21 V1.0 for the pcb. Notice the removed ground plane around the gate driver.

EDIT: How the zeners will be placed on the mosfet

My source of inspiration:
https://flore.unifi.it/retrieve/handle/2158/1078229/219832/Average_Buck.pdf
Falstad Simulation:
https: slash slash tinyurl.com slash yzst27j5
I manually tested all combinations of input voltages (109V; 150V) and loads (CC [1Ohm load], CV (open circuit), max power[2.5 Ohms]) with hard transients and all voltage and current limits of the components chosen were met.
EDIT: Falstad Simulation of short-circuit(100mOhm). I realised that I will need a fuse of ~ 30A to cope with the capacitor discharge burst. But the MOSFETs should be fine (rated at 180A burst).


texts:
I am porting a working sequential circuit from a DE0-Nano to a DE5-Net. The circuit is driven by one global 50 MHz clock signal. The circuit only has one input and one output port for serial communication.
The VHDL of my circuit is generated and I don't know how to interpret the DE5-Net documentation. I've done some preparatory work on the pin assignments and would appreciate if somebody can confirm my "choices" of the pin assignments are correct. I also need to know the pin name of the 50 MHz clock.
The ports of my top entity (DE5-Net) are as follows:

clock (50 MHz input bit; Pin ??)

reset (input bit: button 0; Pin AK15?)

RX (input bit; Pin AE18?)

TX (output bit; Pin AE17?)

REn (output bit: always 0?; Pin AF17?)

DE (output bit: always 1?; Pin AG14?)

TE (output bit: always 0?; Pin AF16?)

My Quartus compiler accepts the VHDL and pin settings, but I need some confirmation my choices are correct.
FWIW I understand there are more efficient ways to do the communication, but I first want to get a working single bit version.


texts: Frequency selective operational amplifier circuit

texts:
I have also question about this question?
 Q1.What factors mean that the potentiometer wiper position relating to k=o.5 is not necessarily equal to the mid point when measured outside the circuit?
Q2. Set the input frequency to ,firstly 25kHz and secondly 200Hz and observe the variation in output amplitude at these frequencies as you vary the position of the potentiometer.
Discusssion the action of the circuit at different frequencies in relation to the frequency-dependent gain profile seen in your plots.


texts: Will a battery short out when the terminals are directly connected together or will internal resistance save it?

texts:
I intended to make a simple electromagnet, then I saw this video where the user is connecting wires together with no resistance at all. I was wondering why it doesn't short out and make the battery dead.

Does this 9v Hi-Watt battery have internal resistance that will prevent shorting out?

If so what will be the current flowing through the battery and how long the battery can last powering the electromagnet, since capacity (like 1000mAh) is not mentioned on it?


texts:
Background: I am trying to reverse engineer a small endoscopic camera for a class project. The camera is connected to its own screen, and I do not have the specs for either. Thus far I have learned that the signal that it provides is a composite video signal (because the circuit board for the screen has a TI chip capable of decoding PAL/NTSC/SECAM signals), but I do not know which of the 3 types of composite signals it is.

Problem: I am trying to bypass the screen and attach the camera to my own hardware. However, when I do this the image is black-and-white with rainbow overlay:

The screen that comes with the camera provides the correct color image. I am using a composite to USB dongle I bought on Amazon. I tested the dongle on other composite signals and it works just fine. But when I connect it to this camera it shows the rainbow artifacts you saw above.

The camera provides nice colored picture when used with its own screen.

The colorburst frequency is the one for NTSC.

Here is a trace:

What could be the reason for the rainbow artifacts? Any ideas how to get the video signal from the camera without relying on the screen it comes with?


texts: Trouble calculating time to drain a capacitor

texts:
Introduction

I'm having trouble producing an equation that involving my MAX756 boost chip, a load and my 1.5F capacitor.

Basically I'm trying to find out how long it would take for a 1.5F capacitor to discharge from Va to Vb when connected to a loaded RLC boost converter.

Here's what I've got far.

Consider this: the MAX756 boost chip has a feedback loop built in to modify it's frequency so it will always (within reason) output 5V.

There is a load of 62.5 ohms equating to a current demand of 80mA.
Now according to the datasheet, the boost chip has approximately 80% efficiency so to produce 400mW (5V 80mA) it would require 500mW to keep outputting 5V at 80mA.

Here's where the capacitor comes into play. I have a 1.5F capacitor supplying the boost chip and the load.
Since my power demand is constant, that means \$R=\dfrac{V^2}{P}\$ right?
I say this because in order to keep outputting 5 volt power, the boost chip will have to draw more and more current as the voltage across the capacitor falls.

I was trying to balance the equations with these cap draining equations but Wolfram wasn't much help

What am I missing?


texts: Is it ok to 'snake' the flow of my schematic?

texts:
I recently watched this video by EEVblog on drawing schematics. One thing he talked extensively about was that the logical flow of a schematic should flow from left to right.

Whilst this makes perfect sense to me, I have recently found myself in a situation where it would be easier to have my 'flow' snake around on multiple lines. (That is a poor description so I attached a picture below). I know the schematic isn't finished / naming is not in it's final form.

My question is whether or not this is considered 'bad practice' or if this is a common thing to see in schematics to make the drawing neater overall. Also, in the second line of ICs I flipped the symbol to make it easier to draw connections if I go with this flow. Is this also a common thing to see?


texts: Difference between disconnector, circuit breaker and load break switch?

texts:
There are various types of devices available for carrying out the switching and tasks.

I have a question about the differences between disconnectors, circuit breakers and load break switches especially at high voltages.

Are there any other types of switches worth mentioning?


texts: The solution use Thevenin's theorem to solve the problem,but i can't understand why

texts:
This solution use Thevenin's theorem to solve the problem,but i can't really understand its meaning ,hoping someone can explain them to me!

Question:determine the I value

Sol:

\$R_{th}=2//4=\frac{4}{3}=1.333\$,\$//\$ means parallel

simulate this circuit – Schematic created using CircuitLab

\$V_x=(4//2)(2+\frac{-10}{2})=-4\$,where does \$\frac{-10}{2}\$ come from?i don't understand!

\$V_A-V_B=-4 \times \frac{1}{2}-(-10)=8\$,where does \$\frac{1}{2}\$ come from?i don't understand!

simulate this circuit

\$I=\frac{14}{\frac{7}{3}}=6A\$


texts: Why does MPLAB IDE has so many compilers?

texts:
I have learnt that the MPLAB IDE has different compilers like C18, XC8 and HI-Tech.

I want to know the following things:

Why are there different compilers when one can do the job?
Are certain compilers only used for specific microcontrollers?
Are there more compilers than these 3 that I need to be aware of?
If any compiler can be used for say compiling PIC18F code, then what decides which one I choose? I really want to know how to decide which one to go with.


texts: Ultra low power/ simple flashing circuit

texts:
ideally I want this to run off coin cell batteries. I found a circuit that uses transistors and capacitors but the voltage requirements are higher than I want. Is there any way I can make this circuit circuit low power?

Any other ideas would be awesome


texts: Solving for steady state voltages (Op-Amp)

texts:
simulate this circuit – Schematic created using CircuitLab

so I have this Op-Amp problem. I need to find for the values of V1, V2 and Vout for t > 0. I have this solution but I'm not sure if I got it right. If not, what part did I have an error?

It's not in the picture but the continuity variables V1 and V2 both have a value of 1 volt. Also, I don't know how to interchange the polarities but the positive terminal of the Op-Amp should be on top.


texts: Arduino analog input pin impacts incoming signal

texts:
I have a hall sensor throttle which outputs a signal that scales between 0.8 and 3.6V. The problem is that when I connect it to an Arduino MEGA2560 analog input pin, the voltage never goes over 2.3V, either when measuring it with a multimeter or using the Serial port. It's like something in the Arduino limits the voltage to this value. What could this be due to and how can I solve it?

simulate this circuit – Schematic created using CircuitLab

The 2.3V are measured between the A2 pin on the Arduino and the throttle


texts: Different results for different parallel ports, same circuit. why?

texts:
This is my programmer circuit:

I decided to try the HCT version of the nor gate (74HCT02) and I also decided to omit the capacitor to the reset. I selected 10K for all resistors except for reset, I used a 220 ohm resistor.

I did a very basic reset test on two different computers each with a parallel port.

Computer 1 is an old IBM pentium 4 with a built-in parallel port. I ran tests in Qbasic for DOS from a boot CD with no other drivers loaded.

I did the following test and got the following results on Computer 1:

Output value 1 to 378h.
Got returned value C7h from 379h (seems normal)
Output value 0 to 378h
Got returned value 47h from 379h (seems normal)

Now Computer 2 is linux with only the basic parallel port driver loaded and with ACPI extensions disabled but the tests are awful. Here's the results:

I did the following test and got the following results on Computer 1:

Output value 1 to 378h.
Got returned value C0h from 379h (seems normal maybe)
Output value 0 to 378h
Got returned value C0h from 379h (somethings wrong)

Whats weird is that neither parallel port is damaged and I always run circuit tests on computer 1 before I use the circuit in computer 2.

So then I thought use 10K pull-up resistors on the data input lines, but that made no difference at all.

Is there some modification I can perform in my circuit to make it work with ALL parallel ports instead of only certain ones?

I also tried disabling the parallel port drivers in linux one-by-one to see if I get more favorable results and I couldn't.

On both computers I setup my port to SPP with no bidirectional capability and same address on both computers (378-37Ah)

And yes I have tested the reset line on my circuit with a voltmeter when I ran the tests and that part responded normally.


texts: How to see Signal frequency and Sampling frequency on the frequency spectrum

texts:
If I have a 100 Hz periodic analog signal and let us say it is band limited to 1kHz and I sample it at 3 kHz. If I want to see its frequency spectrum then how to differentiate between the signal frequency 100 Hz from the sampling frequency 3 kHz in the spectrum?

Edit:

What I understand is that frequency spectrum shows the frequency components at even or odd or mix multiples of a fundamental frequency. But what I don't understand is that whether the frequency is the periodic signal frequency or the sampling frequency?

If it is the harmonics of the fundamental signal frequency then how to find out the sampling frequency from looking at the spectrum?


texts:
I just can't get my head around how these RF transmitters work:

simulate this circuit – Schematic created using CircuitLab

What I do know about them is the following, correct me if I am wrong. L1 and C4 form resonant system, which without other parts of the circuit would slow down due to dissipated energy. I am also aware that Q1 is operated in forward active region, but why? Also what's the purpose of C5? Why with this setup L1 and C4 keep on going?


texts:
Yes, another question about this DDS. However, I think mine is sufficiently different from the others I've read.

I purchased an AD9850 board on Amazon for $17 from "NooElec" (see here). I've been testing it out tonight, and it operates very strangely. I've read where these AD9850 PCBs (often made in China) sometimes use fake chips or have bad designs. Mine seems to have shipped from the US, but its country of origin is questionable.

I'm given to understand that the DDS output attenuates at higher frequencies. However, I've been playing with my board hooked to my oscilloscope, and there is gross attenuation output for frequencies as low as 5 MHz. (The chip itself is designed for 60+ MHz). In fact, the output voltage increases and decreases repeatedly with increasing frequency. Some sample points:

100 kHz: 1.13 Vpp
500 kHz: 1.08 Vpp (same)
1 MHz: 1.1.08 Vpp (same)
2 Mhz: 1.15 Vpp (slight increase)
3 MHz: 1.38 Vpp (mega increase)
4 Mhz: 1.32 Vpp (slight decrease)
5 MHz: 0.975 Vpp (mega decrease)
6 MHz: 0.660 Vpp (mega decrease)
7 MHz: 0.220 Vpp (mega decrease)
8 Mhz: 0.400 Vpp (mega increase)
9 Mhz: 0.400 Vpp (same)
10 Mhz: 0.150 Vpp (mega decrease)
20 MHz: 0.340 Vpp (mega increase)
30 Mhz: 0.150 Vpp (mega decrease)
60 Mhz: 0.150 Vpp (same)

This is the only frequency synthesizer I've used (except for some lab-quality function generators). Should I be expecting this kind of weird behavior from a AD9850 board? I understand the output can attenuate, but can it really attenuate so much so quickly and then increase again? Or do I just have a bad board?

Note that I'm not using filters on the output. If you're curious, I'm operating the board with a Raspberry Pi 2 and code from Tom Herbison.


texts:
Sorry for the vague title: I'm a bit of a noob at analogue electronics, more a logic &software guy. Basic problem is I'm sitting at the end of a cable with a USB powered Arduino trying to send inverted TTL serial to an object at the other end of the cable. I've checked the protocol by wire sniffing with the same setup as it was talking to another device but I can't make it take any notice of me sending commands

I was wondering if it could be because I am taking the arduino power from the USB and not the device?

Out of the arduino i use a 2n3904 transistor to negate the UART signal (taking power from the arduino 5v supply), looks the same on the scope as what the real controller is sending.

I've hacked up the schematic as shown here

and I'm trying to replace what is on the right.

The 7V is not very stable, fluctuates around 6.5-7.5 V is there a good regulator chip to get 5 V out from there?

Cheers


texts:
I was trying a basic transistor circuit to understand transistors (LED on the collector without a base limiting resistor ).

Now on to the next step, to know where and when to put what values of resistors so that the photoresistor and S8050 D331 transistor I have together work as a dark detector.

I need to explain to myself why the circuit does not work if the photoresistor or the load or the extra base resistor are not in their exact positions.

I was referring to http://www.petervis.com/GCSE_Design_and_Technology_Electronic_Products/Transistor_Bias_Calculator/Transistor_Bias_Calculator.html and i have trouble finding the values and calculating them.

Q1: is this the only way to go about it? Suppose a middle school kid is doing this for a science project, how does the kid understand which resistor to put where?

Q2: Assuming this is the only way - for S8050 D331. How do I decipher which values to use in the calculator above? http://alltransistors.com/transistor.php?transistor=52916

simulate this circuit – Schematic created using CircuitLab

The resistance of photoresistor is unknown (am using a snap circuits kit - part 6SCRP).

Q3: If i move the photoresistor to the left of the voltage divider and the 5.1K resistor to the right, OR if i put the load on collector the circuit does not work.
It works perfectly when the potentiometer is at one of the extremes (I guess it is high).

I want to understand with calculations, how things work.


texts: PCF8576 with VIM-878 LCD contrast problem

texts:
Hello I have circuit with LCD driver PCF8576 and VIM878 LCD
Vdd and VLCD for PCF I connected to 3.3V, but conrast is not good.
Only when I look at an angle, I can see well.
I'm using 4 backplanes
1/2 and 1/3 bias give this common effect.
Regards


texts: I want to take 30ns pulse signals from BNC cables and send them to pins on an FPGA board. I have the board in a metal box with ungrounded BNC connectors mounted on it. What's the best way to pass the signal a few more inches to the board without getting reflections on the lines? Can I just use a twisted pair of wires and terminate it with 50 ohms? Should I use RG316 cable? Should I connect all the ground lines at a single point and connect that to the box?


texts: Why is grounding required in a transistor circuit?

texts:
This picture is given in my textbook regarding an n-p-n transistor circuit:

Why is the emitter grounded? Why can't it be directly and only connected to the negative terminal of Vcc?


texts: Why would a power cable need copper wire shielding?

texts:
Today I witnessed burying 10 kilovolt power cable in the ground. I noted the cable mark and Googled it. The description is rather interesting. It's a single conductor cable - it takes three such cables for a three-phase line. The specification (it's in Russian, so I might do the translation wrong) lists the following components:

a set of aluminum wires with total cross-section of 240 square millimeters
several layers of plastic surrounding that set of wires
a "separating layer" made of "water blocking conductive tape"
a shield of copper wires with total cross-section of at least 25 square millimeters
a "separating layer"
one more layer of plastic

Now I understand that at 10 kilovolts insulation is not trivial - a layer of duct tape won't do and that explains why there are so many layers of plastic. Also the cable must be not trivial to damage so there's need for the outer layer.

But what's the reason for the copper wire shielding? What purpose does it serve?


texts: How Does Osram Measure Pulse Handling Capacity?

texts: Looking at datasheets like the SFH4641 from Osram, I noticed the pulse handling capacity diagram, and although I hadn't really thought about it before, I don't know how they measure that. Niavely, they could hook up LEDs under a bunch of conditions: different pulse length, duty cycle, and current, and look at degradation over say 500 hours. But to do that Osram would have to have 10 leds per condition for nearly 1k conditions, with maybe another 3x for uncertainty. But that seems like either a huge rig to measure all those LEDs, or a long time, all for a diagram. Does anyone know how they actually do this? Are there short cuts I am not aware of?


texts: Soft Starter Sizing for No Load Testing of Motors

texts:
Don't know if this would be more appropriate on any other stackexchange site but my question is :

How do you evaluate the sizing of a softstarter for no-load testing of an induction motor ?? For example, a 75kW starter would be used for on load starting of a 75kW motor but on no-load the starter required should be much less. I'm guessing around 25 ~ 35 kW but have no idea on how to best evaluate this.


texts: Trouble identifying resistor with 0.05 tolerance

texts:
Having probs identifying this one - and can't find a replacement. Any hints would be appreciated.

Thanks.


texts:
I am trying to build a 3D scanner which can work with USB power. I am using an IR camera and a IR projector. I would like to scan objects up to a distance of 4m (indoor) with minimum 640x480 resolution.

Does anyone know how to project a fixed IR pattern using a projector or IR LEDs. I am trying to design a 3D scanner, finding the IR camera is easy but I am having problem finding a low-power IR projector (or speckle projector). Any other ideas like using only IR LEDs in the design?


texts:
Perhaps someone can help me. I have a problem with the trigger function in LTSpice.

I load a PWL file and add the following Syntax behind it:
PWL (File.xx) Trigger V(n001)>1

LTSpice gave me an error saying Unknown parameter "trigger".

Does anyone know why the trigger is not working?


texts:
I am working on a project that uses a TCRT5000 reflective optical sensor.
Sensor datasheet is here

I tested this sensor in a room, the voltage at the output pin is high it is above 2.5V. While showing my hands, this voltage is reduces to below 1V.
When I tested this sensor in daylight, without any obstacles the voltage is below 500mV.

Is there an error in testing?
Does the daylight affect the sensor reading?
How can I use this sensor in both indoor and outdoor applications?


texts:
I'm having trouble designing a circuit using an Op-Amp (741) to generate pulses.
The task given to me is:

  Design a pulse generator with a duty cycle that is adjustable from 0 to 100% and whose frequency can be set between 500Hz and 1KHz. Only DC supply may be used.

I found the following diagram:

Now, I know you can set the frequency by adjusting R2, but I'm unsure how to adjust the duty cycle (make R a potentiometer?). Also, what kind of values can be expected for the resistors and capacitor?

Thank you


texts: How can I use half-wave rectified 120VAC to activate a PLC input?

texts:
I am working with a CLICK PLC with the C0-08NA 120VAC input module.

According to the documentation, the C0-08NA's equivalent input circuit looks like this:

A device I need to interface with is powered by 120VAC but uses diodes at various points in its "logic" to rectify the signal.  I need to read one of these signals with this PLC, to determine if it's Off or On.

As a test, if I place a 1N4003 diode in series with a 120VAC input and connect it to one of the C-08NA's input pins, the input light flashes very briefly once, then stays off until the next time I touch the wire to the input. This obviously prevents me from detecting an "on" condition from this voltage level.

I assume this is because the rectified AC would only be about 60V instead of the 80V required to turn on the input, per the specifications.

What is a simple and safe way to convert this signal into a level that's readable by this PLC?  Note that the PLC also has 24VDC inputs available if that helps.  Commercially-available DIN-mount components are preferred.

FYI I tried actuating a 120VAC relay with this rectified signal and it just buzzes but won't close.

Thanks for any advice.


texts: Monitoring an output using Quartus SignalTap

texts:
I have a design which includes two modules, one that transmits parallel data to a UART_TX module, and the UART_TX module outputs the data serially. The data transmitter uses a state machine to output different data every time using an 8-bit bus. It looks something like this:

When the send pin is '1' the transmission starts. Of course it's way more complicated, as the two modules need to synchronize between them.

I am connecting the FPGA to an outside device which is supposed to respond when getting the data from the UART, but it doesn't.

In a Modelsim simulation everything is well so I am having trouble understanding what is wrong. I have also already used to exact same UART_TX module and it worked with the same outside device (but a bit different design) so I know for sure the problem is not with the UART module.

I would like to use SignalTap in Quartus to monitor the tx_out pin, but I don't know how, since I can only see the monitored pins for a limited period of time (unlike a simulation, where you can see what happens after 10us, 20us, 40us and so on).
Is it possible to do that? Can I know what my output is?


texts:
This circuit is for a temperature sensor with its output signal being amplified so as to be better processed.
What is the role of RI1 which is the input resistor of the non-inverting pin of the LM358.


texts:
I have a server power supply model HSTNS-PA01. I will be using it to power hard drives for a NAS. The problem is, this PSU outputs 12.8V with and without load, which is out of the 5% tolerance allowed for computer components. I want to lower the voltage to a safe 12.5 (or even lower). After doing some research, it looks like people have been using this PSU for RC chargers and alike by raising the voltage to 13.7 and such. My only hope now is that by using the voltage sense function I could make it realise it's out of spec for a 12V PSU. My question is, will I hurt anything if I connect the +12V RS+ directly to the 12V+ output, and the +12V RS- directly to the GND and powering on the PSU without any load attached? If it would, what should I try to lower the voltage by using the logic level pins?

This is it's pinout:


texts: ATMEGA UART transmition with flow control

texts:
Background

I'm using an ATmega328P to send data to another device at a high baud rate (230400). The device I'm sending data to supports flow control and raises the RTS signal when it needs to hold the transmission.
The problem is that the device is expecting me to stop the transmission immediately after RTS is asserted.

The ATmega328P has a transmission buffer (UDR) and a shift register from which data is sent to the TX line. Since the ATmega328P does not support flow control in hardware, I'm implementing it in software. Before sending (before writing to UDR) I'm checking RTS and waiting until it goes low, but apparently this is not enough because data in the transmit buffer and shift register is still being sent and a full byte could still be sent after RTS is asserted when the ATmega328P flushes its buffers.

Apparently, disabling the transmitter when RTS is asserted (setting the TXEN to zero) does not help since it will not become effective until ongoing and pending transmissions are completed, according to the documentation section 19.6.5.

A workaround could be to wait until Transmit Complete (TXC) before sending each byte, but this would impact the data rate since I'm not sending the byte stream back-to-back even when RTS is not asserted (I'm starting to send a new byte only after the previous one was completely sent).

My question is:

With the ATmega328P, is there a way to support RTS flow control in the transmitter while still enjoying the pipelining provided by the transmit buffer and shift register?


texts:
I am really new to the world of building hardware and software electronic devices and need help with a situation.

First off let me give a brief background on what I know about electronics and software programming so the community gets a good idea on what to expect from my knowledgebase.

I know a little Java, C#, Python and AT commands, I have a good idea of I2C and how to program small things on Raspberry Pi's.

So now down to my question.

I ordered a DM9000CEP V5 board and want to setup the initial settings to enable the board to talk on my network. I have read through the documentation on the chipset but am not able to get my head wrapped around how to setup, for instance a serial connection with 9600 baud serial to program the EEPROM. Maybe I am missing something because I am not just yet use to thinking out of the box.

Please, can someone tell me which pins to use to initially setup the board?

I have attached the documentation for the chipset and pictures showing the pinouts on the GPIO side of the board.

Thanks in advance.

Ross Kopp

Here is the link to the DM9000B spec sheet:
http://www.davicom.com.tw/userfile/24247/DM9000B-DS-F03-04072014.pdf


texts: The talk of current amplifier vs voltage in audio?

texts: I cannot find any good scientific basis for the supposed benefit of designing low wattage current source amplifiers in lieu of the traditional voltage amplifier to drive a loud speaker. Given, this has mostly been discussed in the "Hi-fi" communities, can anyone shed light on the alleged merits of this?


texts: How much difference in net length is ok?

texts:
Sorry, but I couldn't find a better title. Consider the following: I have an address/data bus interface. Intended frequency of the D/A bus would be around 10-50MHz.

According to the datasheet of the device in question (OMAP-L138) the maximum clock frequency appears to be around 100MHz (tCLK(min) is specified as 10ns). I would guess that the rise time of the signals would be around 200ps. But this is really just a guess since I wasn't able to get the information from said manual.

Now I was wondering if there was a rule of thumb of how much (length) the traces may differ, e.g. how much A1 may be offset from A2.


texts: Vivado Integrated Logic Analyzer Waveform empty

texts:
I am using Vivado 15.2 on Linux with a Zynq FPGA. My design contains a single Integrated Logic Analyzer (ILA) core with some signals connected to it. Downloading works find and the hardware-manager loads the dashboard view as expected. The only problem, is that the Waveform window does not allow me to add any signals. The only thing it shows a is "No Content"  message. In the Trigger-Setup window it is no problem to select the signals.
What do I need to change to see the signals in the Dashboard?


texts: How to recognize an OTG USB port on an embedded device?

texts:
Sorry for the noob question, I'm trying to flash a new firmware on a tv box with rk3066. The datasheet says that the chip has OTG capability but there are 3 usb ports on the board and I can't tell which one it is:

How can I tell which port supports OTG? Also would it be safe to try connecting each port to my pc to test which port gets recognized or would the VCC voltage from the board damage my PC?
Thanks in advance.


texts: Common emitter circuit - can't understand negative feedback

texts:
I have a problem with understanding how does the negative feedback of this circuit work.

In all books that I read it is said that "with the rise of temperature, collector current increases". Why is that? I know that \$\beta\$ increases as well and \$U_{BE}\$ decreases. Looking at the Thevenin's configuration of \$R_1\$ and \$R_2\$:

We can write that base's potential (in Polish word for 'shunt' starts with b, so don't mind index at the image above)

\$V_B=E_s-I_BR_S=U_{CC}\cdot\frac{R_2}{R_1+R_2}-I_B\cdot\frac{R_1\cdot R_2}{R_1+R_2}\$

Hence, \$U_{BE}=V_B-V_E=U_{CC}\cdot\frac{R_2}{R_1+R_2}-I_B\cdot\frac{R_1\cdot R_2}{R_1+R_2}-I_ER_E\$

Now assume, that the temperature had increased. This means that \$U_{BE}\$ will decrease and \$\beta\$ will increase. What I don't understand is how the thought process goes next.


texts: Batteries not supplying enough voltage in DC motor circuit

texts:
I'm building a MOSFET controlled DC motor circuit with a 6V battery as the supply. Although when I turn the MOSFET on, the voltage at the battery positive drops to about 2.5V. I thought it could be back emf from the motor, but it stays at the lower voltage.
Maybe it's the way I set up the circuit?
Can anyone see what might be causing this problem?

simulate this circuit – Schematic created using CircuitLab

Note: That the inductance in the schematic for the motor is made-up. And that I am using an IRLB8721 MOSFET, not the one in the schematic.

Thank you for helping.

Edit: The solution it seems that the batterys I'm using either cannot supply enough current or they are low on charge. Thanks!


texts:
From this tutorial, I can print local time when I code using codeblock.
https://www.tutorialspoint.com/c_standard_library/c_function_localtime.htm

I am measuring capacitance by atmega644. I read the capacitance data from the ADC and print it. I want to add the local time so that I can know how much is the capacitance at a specific time.

I try the exact same thing of this tutorial and get the following errors. How can I print local time along with my continuous capacitance measurement?


texts: Using old laptop LCD as external VGA screen

texts:
I have a few old laptops with good LCD panels that I wish to salvage and use as external VGA screen on other computers.

I'am no expert in electronics but I work with computers and know the basics of it. I also did a lot of research on the subject and did my best with no success. I invested some money on parts and really want to finish it but I can't do it without help.

So the LCD panel uses a LVDS interface to connect to the LCD controller board (MT-561B very similar to MT-6820-B).

This is the LCD board. I have some doubts on the red connector (1), the pin layout is printed in the board. I only connected the first ground and the first VCC input, leaving the others not connected. ADJ stands for the brightness adjustments, I'm guessing this is an output to the inverter to reduce the backlight brightness but I'm not sure. I don't really know what BL is but I have read somewhere that is like an on/off pin so I connected it to the 5V.

There is a jumper to choose 5V or 3.3V (4). I'am pretty sure I should use 5v but tried both with no success.

I think I got the LVDS interface cable right because in the pin layout the VCC pins match the red wires in the cable. The keyboard is connected in place as well. (3)

Another thing that I am not 100% sure is the pin mapping for the resolution (2). I want to use 1024x768 (8-1 or 6-1) to test it out, it's not the native resolution but It must be supported right?

There was no pin layout for the original LCD inverter so I bought another one, I can't really tell the specifications (can't access Aliexpress) but I'am sure it supports 12V input. Again I just connected the first VCC and GND pins, ADJ was connected to the LCD board and N/F I found out it means like No Function and should be connected to GND.

Everything is wired up (and not working) as the following layout:

I have an ATX power supply from a desktop PC and I use it to get the 12V and 5V that I think I need to use.

My results so far:

When I turn the power on the LCD panel backlight lights up just a bit, goes off and the keyboard LED keeps on flashing.

If I connect two LCD panels to the LCD inverter both backlights stay on, the keyboard LED flashes too.

This makes me believe that the backlights and inverter are working.

I'm sorry for the long question but I did everything I could and tried to explain it in the best way, now I'm out of moves. What do you think is wrong with the project and what should do next to try to fix it?

Thanks in advance

(I might have connected the 12V on the LCD controller which should get 5V)

EDIT:

The characters on the VGA chip are very small, I could not get a picture and maybe some could be wrong:

Himax
Hx6856-A
080LAG
538DNTCC
955710
XM27345


texts: Compare output of logic gates but ignore their difference due to propagation delays

texts:
I am triggering a current source for a coil. I made a safety circuit with a bistable multivibrator, which forces the trigger sent to the hardware to have some maximum duration. This is a duty-cycle protection for the coil, to avoid it reaching high temperatures. So, even if the user leaves the trigger on HIGH for too long, the duty-cycle protection box makes sure the hardware does not stay on for that long (I also have a second multivibrator that makes sure cannot turn the coil back on before a certain set time but that's not needed here).
I would like to add a warning light to let the user know that the trigger they sent was ON for too long, and the safety box had to switch it off.

A simple way could be adding an exclusive OR gate that compares the user-trigger and the hardware-trigger, so that the output is HIGH only when the two triggers are different. This HIGH drives an LED which gives me a warning:

Problem: I am guessing the LED will be turned on even during the "propagation delay" interval shown in my first diagram, where the two triggers are different. I know it might be for a split second, but I want to add a D flip flop with a reset button to this circuit so that the LED stays on until the user notices it and pushes the reset button.
How can I only make my circuit "not care" about the difference between the triggers due to the propagation delay?


texts: What is this connector that allows wires to be pushed in without stripping first?

texts:
I have exhausted my resources on Google trying to find this connector, mainly because I'm not quite sure what to search for. Per the photos, it looks like you can push the wires in and two metal conductors strips the housing.

In addition, how does one go about finding such things online? I have tried reverse image searches, looking through the thousands of Mouser catalogs, and tried every sequence of keywords I could think of.


texts: How can I improve the common mode rejection ratio for TI ADS1299 ADC?

texts:
I am using 2 TI ADS1299 (home page, datasheet) devices with Raspberry Pi4 and I want to improve the common mode rejection ratio.
I don't understand the proposed techniques such as the isolation capacitance, the protection resistance and the RLD amplifier. I'm still a beginner, so can anyone help me what technique I must use and the required circuit?


texts: Drop Voltage using Resistor: is it practical?

texts:
I should probably say that this a basic question, I don't know much about this stuff, please don't be too hard on me.

Ok so I kind of thought it would be fun if I could light up 12V halogen lamps using 220V power supply, so I did a few calculations:
The bulb is rated at 60W, so according to P=VI, it should draw 5A current. Now since the input voltage is 220V and I need 12V, the voltage drop across the resistor will have to be 220-12=208V. The bulb draws 5A current so according to R=V/I, so I would need a 41.6 Ohm resistor, say approx. 40 Ohm.

I wanted to ask if my calculations are correct and if it is indeed safe and practical to drop voltage using resistors. I would also like some details on what kind of resistor I should use. Thanks.


texts: What could cause a microcontroller on a board not to accept programming?

texts:
EDIT: To summarise - when I take the microcontroller off the board, it works. But when I leave it on the board and try to program it, I cannot.

I have designed a PCB and had it fabricated. This PCB has ICSP programming pins specifically for the purpose of allowing it to be reprogrammed in-situ.

My problem is that the chip (ATtiny44A) will not accept new programming - indeed, the programmer hardware doesn't even detect its presence! - unless I remove it from the board and place it into a ZIF socket.

When I try to program the chip on the board (using a clone USBasp and avrdude), it says "target didn't answer" and such - in other words, no chip found. Very occasionally it works (like, one time in fifty), but reports verification errors and the like.

I have tested that the ICSP pins are connected to the correct pins of the chip using a multimeter; and also checked for shorts between the pins.

I have partially assembled the board. I realise that ICSP can often be negatively affected by the presence of other connected circuitry; but I have not yet placed any components that should cause a problem.

Here is the schematic. I have greyed out parts that are not yet present on the board. As you can see, nothing has been connected to the microcontroller by more than one wire, and therefore does not exist:

Here are some pictures of the board. The enamelled wire is present because I damaged a trace on the board whilst soldering. Two of the resistors underneath the chip are only connected at one end, in an attempt to diagnose the problem.

I've tried everything I can think of. What could be causing this strange behaviour?


texts: Is there a shortcut key in ModelSim so that part of the code I wrote will be turned to a comment:?

texts:
Is there a shortcut key in ModelSim so that part of the code I wrote will be turned to a comment?
Just like here, we use Ctrl + k. I wonder if there is also in ModelSim.


texts:
This is an all-in-one Dell Inspiron One 2305. I received it for free because it was "having issues with the RAM." However, the power light was a solid amber when plugged in, and I was unable to manually turn it on or off (other than by disconnecting the power cable). I decided to bake the board, as it seems to consistently suffer from faulty soldering joints due to overheating. This did not solve the amber light, but I am now able to turn the computer on and off manually via the power button. The screen does not light up, and there are no POST beeps. Upon further inspection I discovered what appeared to be a blown ceramic capacitor (though I'm no electrical engineer, so I can't be certain). It was fairly dark and flaked away.  I wasn't able to salvage a part number from it. I'm not certain that this is the issue causing the amber light, but I thought it was a good possibility that it was playing a role in the situation.

I know it would be easier to just replace the board, but I've invested a good amount of time into trying to fix this computer - now I'm just curious if it can be fixed.

So, my real question: is it possible to fix a small ceramic capacitor like this, and how might I go about finding the correct type/value of the capacitor?


texts: Altium: how to export netlist with net class data from Altium?

texts:
I am testing Altium for some simple electrical harness design. Now I am trying to generate a report for manual wiring and would like to have typical netlist data (nets and pins) together with net class in a spreadsheet. I plan to use net classes to define wire data - part number, maybe mounting directives, etc.

The only netlist format that I found to contain this data is EDIF, but parsing that in to a spreadsheet is a task not for the fainthearted.

PCB editor has some more output features, but I have yet to try everything out.

So, how to export netlist with net class data from Altium?


texts: My stepper motor works, but it shouldn't. Either the cables are mislabeled or the sequence is incorrect

texts:
I have a Nema 17 stepper motor and a TB6612 driver from Adafruit. To control this stepper motor I am using a Raspberry Pi. I cannot figure out which cables in my stepper correspond to which coils: the datasheet included with the stepper says that the BLK and GRN cables are from one coil, and the other two cables, RED and BLU, correspond to the other coil. This could be true since the resistance between these pairs of cables is around 30Ω.

Now, if I plug it that way to my driver (it has two outputs, one for each coil), the stepper only vibrates. I checked each possible way to plug the stepper and these are the 6 ways that actually worked:

BLK and RED to OUT1, GRN and BLU to OUT2
RED and GRN to OUT1, BLU and BLK to OUT2
GRN and BLU to OUT1, BLK and RED to OUT2
BLK and BLU to OUT1, GRN and RED to OUT2
RED and BLK to OUT1, BLU and GRN to OUT2
GRN and RED to OUT1, BLK and BLU to OUT2

The first three turn clockwise, the other three counterclockwise.

Just to make sure you have all the available information, I checked all the possible inputs for my driver, and got that these inputs yield the following outputs:

[0,1,1,1] --> [1,0,0,0]

[0,0,1,1] --> [1,1,0,0]

[1,0,1,1] --> [0,1,0,0]

[1,0,0,1] --> [0,1,1,0]

[1,1,0,1] --> [0,0,1,0]

[1,1,0,0] --> [0,0,1,1]

[1,1,1,0] --> [0,0,0,1]

[0,1,1,0] --> [1,0,0,1]

So that, for example, if I plug my stepper's cables such that BLK and RED are a pair, and GRN and BLU another one, if my driver's input is [0,1,1,0], it outputs [1,0,0,1], and therefore BLK is high, RED is low, GRN is low, and BLU is high.

Even though I figured out how to make my stepper turn correctly, I want to understand why is it working when the datasheet clearly states that BLK and GRN are a coil, and RED and BLU are another one.

Additional Information

If I change the input sequence, and thus having the following output:

[1,0,0,0] --> [0,1,1,1]

[1,1,0,0] --> [0,0,1,1]

[0,1,0,0] --> [1,0,1,1]

[0,1,1,0] --> [1,0,0,1]

[0,0,1,0] --> [1,1,0,1]

[0,0,1,1] --> [1,1,0,0]

[0,0,0,1] --> [1,1,1,0]

[1,0,0,1] --> [0,1,1,0]

I plug the stepper motor as if BLK and GRN were a coil and RED and BLU another one. Then My stepper motor turns but in a way that is clearly not desirable.

I will appreciate any help you can provide.


texts:
I'm starting a new board using an MSP430, preferably the 5 series.  I'd like to pick a part that is readily available and more likely to be in stock over the long term from one of their distributors. I'd like to go with a BGA part, but from my experience, those parts are the least likely to be stocked, and you're better going with leaded.  That being said, I'd prefer a smaller package.  When I've used other manufacturers processors, they had what you would call the "flagship" model of processor and then other parts within that series that had less functionality.

For example Processor P8051-M7-430 would be the standard part and there would be other parts that were less likely to be in stock within the series, all with varying degress of functionality of the "flagship" part with part numbers such as Processor P8051-M7-431, Processor P8051-M7-433, and Processor P8051-M7-439.Typically the flagship processor was on their eval boards and in stock with their distributors and if for some reason you need another variant of that part, you would have to do a minimum order of something like 3000 from the manufacturer directly.

Is there any rhyme or reason behind which MSP430s are more likely to be stocked or is there a standard part/footprint that is more likely to be stocked at distributors because of it's popularity?


texts: OOC coding in Wireless Radio Mesh Network

texts: Can anyone explain me whether OOC (i.e. optical orthogonal coding) works in radio frequency? Or only for optical/laser technology?


texts: microcontroller output fail safe circuit

texts:
I'm trying to use a microcontroller (pic) to control external LEDs that are powered by batteries.

The actual control of the LED is working fine.  I set an output pin high, and that drives a transistor that controls the LED.

What I'm looking for is a hardware circuit between the pic output pin and the transistor so that if the pic stops (while I'm debugging for example), the LED doesn't draw down all the power in my batteries.  I think the circuit should probably short the output to ground after a second or two?

I assume there must be something based on a RC circuit that could be used, but I have no idea what it is called or how to set it up.

Any ideas would be appreciated.


texts: Sensor communicating with a base station 3.5km away for a rate of 100bytes every 10 sec

texts:
I have a small project that I want to do,
I want to deploy a sensor that is capable of measuring the wind speed and direction from a crop field to my house - distance of about 3.5km.
There is no line-of-sight and I wish to send up to 100 bytes of telemetry every 10 seconds. The sensor should also be capable of receiving up to 50 bytes from the base station (a command to change the sampling rate).
The sensor will have to be powered by a battery.

I am new to the MCU field, what would be the cheapest most power efficient way to accomplish the above ?
Would I need a launchpad with a RF transceiver module for this ?
Would an MCU + RF transceiver module + Battery - be sufficient or would I still need the launchpad ?
What frequencies should I be looking into ?
What about the base station, Can I connect an RF module to a PC ?
What kind of an antenna would I require ? - I have no problem putting a large antenna on the base station side, but on the sensor out there on the field - the antenna will need to be as minimal as possible due to the risk of theft.

I would also appreciate recommendation on suitable books or other relevant reading material, this project is a hobby of mine and I am more than willing to catch up and update on my progress :)

Thank you for your future assistance.
Cheg


texts: Maximum resistance allowing for short circuits

texts:
Consider a contrived circuit consisting of only cell and pot:
(1) a cell with constant voltage V and constant amperage A,
(2) variable resistor of resistance R initially set to its highest finite resistance and used to close the circuit with the cell.

(Assume that the variable resistor has a range of zero ohms to infinity ohms, and that its highest finite setting is guaranteed to create a closed circuit that is not a short circuit for arbitrarily large V and A, and that some resistance R greater than zero ohms is guaranteed to be a short circuit.)

Given a closed, non-open, non-short circuit comprised only of a variable resistor of resistance R, and a cell with amperage A and voltage V, what is the value of R when the circuit shorts out as we reduce R from infinity to zero?


texts: Accidentally soldered in 12v 60ma bulbs in a 14v 95ma circuit - dangerous?

texts: I was replacing some lights in my car's HVAC control box, and I used 12v 60ma bulbs (link), and after reinstalling it in the car (bulbs are working), I was doing some Googling and noticed that some people are using 14v 95ma bulbs.  Lets say that a voltage or current spike occurred and pushed 14v ~95ma, am I in danger of damaging the electronics/PCB, other than blowing the bulbs?


texts: Which are the guidelines for chose which cables should I twist as a pair? For example, suppose the case in which I have 3 cables. One of Vcc, one of GND and another of signal. Which ones should I twist? It would be better twisting signal+GND for better reference to signal (refereed to GND)  or twisting GND+Vcc (for better decoupling)? Anyone may suggest good practices for twisting cables?


texts: When should I be considering an operational transconductance amplifier (OTA)?

texts:
I found a few questions roughly related to this:

How is a transconductance amplifier used to measure current?
Operational Transconductance Amplifier Input Configurations
Dead or alive: Operational transconductance amplifier

but not all have answers and none provide the insight I'm looking for.

I'm reasonably satisfied with my understanding of "conventional" op amps, like say the LM358, and when I should be considering one of them for a circuit design.

However today I came across a chip, the LM13700 as it happens, described as an Operational Transconductance Amplifier (OTA).

I understand transconductance as the transformation of a voltage into a current, so it makes sense to me that an OTA somehow takes (differential) voltage as its input and provides a proportional amount of current as an output, rather than a proportional voltage. What I don't have is an intuition for when this sort of thing is preferable in a circuit.

My question is, What intuitions or rules of thumb would faithfully guide me on when to consider an OTA instead of a "regular" op amp; perhaps illustrated by any "classic" applications where an OTA would be preferred (and why)?

One vague notion I have for an application is in a linear voltage regulator I'm working on, where the op amp drives a transistor to sink current away from the pass transistor; conceptually like this (component values nominal):

simulate this circuit – Schematic created using CircuitLab

This presents a stability problem because the op amp output voltage range is so narrow, roughly \$V_{BE}\$ +/- a few tens of millivolts to change the base current from 0mA to say 20mA. Maybe this is a good job for an OTA?

Am I on the right track? What intuitions about when to consider an OTA would enhance my design skill?


texts:
I've been using the avrdude for quite some time to burn my atmega mcu's. The read / write operations are fast if the code is small in size but it gets a lot slower as the code base grows.

I've noticed that avrdude not only writes from the mcu but also reads the on-chip data. I wasn't able to find anything regarding the issue in man avrdude.

Is it even possible to only write using avrdude?


texts: How to protect single cell Ni-MH battery (overcurrent, undervoltage, overtemperature, etc.) during discharge?

texts:
Story
I am designing a boost converter for a battery powered board. I am planning to use single Ni-MH battery. The needed output voltage is 3V3. The device will be in deep sleep mode (drawing few microamps from the 3V3 output) most of the time. Therefore light load efficiency is one of the key points for me. I have found TPS61021A from TI. However it doesn't implement any protection for batteries.
One of the alternatives is TPS61200. It provides at least UVLO protection but has worse efficiency than TPS61021A at light load.
I haven't designed a power converter circuit containing Ni-MH batteries yet. I think that it is better to include some protections for battery. This won't be a commercial product, it is a personal project. Cost isn't a big issue. I want to learn how to handle Ni-MH battery correctly during discharge.
Operating ambient temperature of the circuit is between -20C and +50C.
As far as I searched, I couldn't find a complete power management IC for Ni-MH batteries, especially for single cell case. Moreover, most of the literature are for lithium batteries. Since the nominal voltage of Ni-MH battery (~1.2V) is lower than lithium ones ( >3.5V), designing a proper protection circuit is more challenging.
So, I have thought 3 protection topcics so far. Please free to add if you think more is necessary.
Undervoltage lockout protection
I want to switch off the converter when the cell voltage is below 0.9V or 1V. Since TPS61200 doesn't have UVLO feature, I have to implement UVLO externally. One option is disabling the converter IC using EN pin. To do this, I may use a voltage reference IC and a comperator or a single transistor basically. However it should also have hysteresis to prevent oscillation.
Overcurrent protection
I am planning to use a resettable PTC fuse to avoid dead shorts actually. Since the battery will only be connected to converter IC, short is possible in case of IC fault. I want to include a loose protection and I think PTC fuse is just fine.
Overtemperature protection
I don't know whether it is meaningful for Ni-MH battery or not. It may be unnecessary since there will be a overcurrent protection. A thermistor based circuit to disable the converter IC via EN pin may be a good option, I think.
For these protections, I couldn't find ready-to-use ICs or schematics. I will be happy if you can direct me for single cell Ni-MH protection.


texts: I'm currently trying to read values from an MPU6050 using an STM32duino, but using an I2C scanner code, the STM32 can't detect the sensor. I've checked all the connections using an avometer and it all seems good. Connecting the connection boards to an arduino works perfectly fine so the board is not busted. I've connected the VCC to +5V and GND to GND, from my experience, the MPU works fine under +5 volts because there is a regulator and my module which is a GY-521 already has pull up resistors. So what am i doing wrong?