texts: Hall sensor confusion with unipolar and bipolar as well as magnetic induction sensitivity

texts:
I want to create a simple bicycle computer that shows my speed and RPM.
I'm thinking of using a TLE4905L or TLE4906L (which I think is more sensitive) - both unipolar.

Now I'm a bit confused about unipolar vs bipolar.
When my wheel spins, the magnet will pass in front of the sensor (sensor is static, magnet is rotating with the wheel on a spoke) with the same orientation, as it passes, the magnetic field increases, then decreases. With unipolar sensors this should count as a rotation (a rising and decreasing edge at the output pin - of course I'll use just one of the edges at the controller level). On the other hand with bipolar sensors I think I'd need two magnets, one near the other oriented with opposing poles towards the sensor, one would make it go high and the opposing pole from the second magnet passing by would make the signal go low, am I understanding this correctly?

Now for the sensitivity of the sensors. Let's assume, for the sake of the argument, a typical fridge magnet at 5mT as per Wikipedia.
With the unipolar versions of the sensors with the TLE4905 (page 8 of the data sheet linked above) the strength of the magnet would not be enough to trigger the sensor which has a Bop=7.5mT.
The TLE4906 is a bit more sensitive at Bop=6.5mT, but still not enough.

Is this right?
Now I either need a stronger magnet or a more sensitive unipolar sensor, right?
If I got the unipolar vs bipolar part right, then the answer should be yes, otherwise I need some explanation on why not.


texts: How much length of nichrome wire needs to be adjusted to mod a 220V toaster to run on 115V?

texts:
I have a Sanyo toaster (10 years old) with me which stopped working yesterday. It was a gift from a friend. Its a 220V 700W 60/50Hz toaster. So, had to run it off my 110V to 220V 1500W voltage converter for this long.

Upon inspecting I noticed that there are two terminals for the LIVE and NEUTRAL. The nichrome close to the live terminal has broken off (more like burned off)and split. So, I may loose like 1 to 2cm of nichrome to rejoin it back to the LIVE terminal. I tested and it works.

I measure the resistance of the nichrome wire and its 393.7 ohm/in. The nichrome wire strips are on some heat resistant plates, with wire length of 4.92 inches. There are total of 10 such strips per plate face. there are 4 such plates. Total 196.8 inches.

So, my question are:
1. Can anyone help to mod this toaster to run on 110V?
2. If I where to run at 115V 700W, do I need to more nichrome or less?
3. If I need more length, will it work by reducing the wattage(like 350-400W) for 115V to get same amount of heat?

NOTE: the third question is kinda dumb. The reason I asked is because my room heater which is 1500W at 115V. When I checked online most counterpart 220V heaters are rated for like 2200W. So, it seems like it needs have the watts half voltage for the= particular temp range. This is just my assumption.

Of course I can go and buy a new 115V toaster, but the point is I would like to know if I can get this back to life if possible.


texts: Finding the non-zero value of ω, such that V and I will be in phase

texts:
Consider the impedance network connected to an AC voltage source in Fig. Q3(a).

i) What is the network's equivalent impedance, in terms of ω?

$$
Z_{eq}=\left(\left(Z_c+R_{10Ω}\right)||L\right)+R_{1Ω}
$$

\begin{align}
Z_c+R_{10Ω}&=10+\frac{-j}{2ω}\\
&=\frac{2ω\left(10\right)-j}{2ω}\\
&=\frac{20ω-j}{2ω}
\end{align}

\begin{align}
\left(Z_c+R_{10Ω}\right)||L&=\left(\frac{1}{jω6}+\frac{2ω}{20ω-j}\right)^{-1}\\
&=\left(\frac{20ω-j+2ω\left(jω6\right)}{\left(jω6\right)\left(20ω-j\right)}\right)^{-1}\\
&=\frac{\left(20ω-j\right)\left(jω6\right)}{20ω-j+j12ω^2}\\
\end{align}

Therefore,
$$
Z_{eq}=\frac{j120ω^2+6ω}{20ω+j\left(12ω^2-1\right)}+1
$$

ii) Find the non-zero value of ω, such that \$V_{in}\$ and \$I_{o}\$ will be in phase.

Since I know that \$Z_{eq}=\frac{V_{in}}{I_o}\$, if they are in phase, their cos(ωt) or sin(ωt) can cancel out each other. So \$Z_{eq}\$ do not have complex part (\$j\$).

My Question

Can I just set all the terms with \$j\$ to 0? Or, I do it in a wrong direction?

Thank you for your help.


texts: How to generate a pwm signal that varies atleast 20times between 0-5V range using Atmeaga32 avr mcu?

texts:
I'm doing a Photovoltaic(PV) Data Logger project in this, a power
MOSFET(IRFZ34N) can be used as load.So i want to vary the gate voltage
using a PWM signal(0-5v range) of MCU & i need at least 2o varying points.
so i am confusing at writing a 'C' code to generate PWM signal.
like 1. what should be the time period of PWM?
    2. how can i vary pwm duty cycle in different steps? and etc..

And please help me, if anything else that i have to do to make my
project success full.
I would be very thank full, if some body help me with answer.


texts: How to avoid melting a 3D Printed Chandelier with LEDS and DC Voltage Drop Across 7m Cable Run of 100A 12v DC

texts:
I am trying to power led strips located inside a custom designed 3D printed chandelier.

I want to find the best solution to power the project and to work out the voltage drop along the cable from the power to the chandelier. Here are my workings and plan:

My led strips require:
$$78.75~A \cdot 12~V = 945~W$$

They have a cable run of 7 meters back to two switching power supplies:

100 A @ 12 V provided by two 12 V output at 50 A drawing 600W from mains. These draw 1200 W of mains voltage (240 V).

There is a design problem related to the 3D printed chandelier - these supplies need to be 7 m away from the chandelier because the 3D print has no ventilation and may melt with the build up of heat from the two 50 A, 12 V switching power supplies.

How can I work out the voltage drop along the cable from the power supply to the chandelier and make a choice for the correct thickness of cable?

How would I work out how much heat:

the leds would produce
the power supplies would produce if the full 78.75 A was being drawn by the LEDs for say 10 min, 30 min, 1 hour, 24 hours etc.

Could I instead deliver 24 V of DC from switching power supplies, ignore the voltage drop across the 7 m of cable and then transform what ever gets to the chandelier to 12 V (and keep the amperage required, a minimum of 78.75 A).

NB. I couldn't have the AC to DC conversion take place close to or inside the sculpture:

the heat generated will be too high, over time the 3D sculpture
would melt
there is no place to locate the large transformers on
or near the sculpture.


texts: howto link an Arduino Light Sensor to a keyboard button

texts:
I have an Arduino Uno and a light sensor. I would like the light sensor to activate the [H] button on my keyboard. If the light sensor is in the dark (1024 I can see in the monitor) it should have the same effect as holding the [H] button until there is light again. How do I go about this?

At this moment The arduino en sensor works, I think I should be able to read out the serialport en then, when the output is near 1024, trigger an event like holding the [H] key. I only have no idea where to look on the web, what words to look for or if this is so basic that there is a piece of coding out there.

working on an art-installation, help is very welcome :)


texts: Input impedance of GPIO pins vs. current protecting resistor

texts:
Novice here.
I have read that the input impedance of GPIO pins on a microcontroller might be in the order of 20 megohm. I’m trying to understand why we then might need a current limiting resistor with a value around 100 ohm.
Why would we need an extra 100 ohm when we already have 20 megohm?
Example circuit from the video

As I said, novice! Thanks for your patience


texts: Where are female to female jumper wires used? They only have provision to allow other wires to be plugged into so cannot be used on breadboards. So, practically, where are they used?


texts: Need to control (fade in/out, not just turn it on and off) a 240 V heat lamp. Is this even possible?

texts: I'm a MechE and i'm way over my head in a project i'm working on. i need to be able to send either an analog or PWM signal to a heat lamp to allow it to fade in and out from dSPACE via a Unity project. is it even possible? I looked into MOSFETs and solid state relays and neither of them seemed to be satisfactory. any help would be awesome.


texts:
Here the gate voltage is 5V and lots of the 12V input voltage stays across drain and source.

Here the gate voltage is 12V and still some voltage stays across drain and source but this time smaller.

I knew that gate voltage just opens the path between drain and source making them act as short circuit. But here, I saw that

1) Apparently drain to source is not short circuted because there is some voltage drop in both cases. Why voltage drops across drain and source?

2) Why applying 5V or 12V to gate makes a difference? Isn't only job of gate voltage is to open/close the drain-source connection?

p.s : both are simulation results using proteus.


texts: Can someone please explain how to hook up this transformer?

texts:
I found an old transformer that I purchased about 10 years ago to build a  regulated dual rail power supply, but never went through with the project.  I still would like to do the project but it has been so long now that I lost any documentation I might have had on this transformer.

Here is a picture of the markings on it and the various leads.  I am not sure which ones to hook up where.  If it helps, the bottom right lead is labeled 1 and the bottom left lead is 4.  Can someone please help me understand how this transformer should be hooked up?

I did research "P241-5" and received a few hits on "quick connect" transformers, but the 36 threw me for a loop, because I think I was after a 12vac stepdown solution.  Could this be a single 115v 36vac, .35A transformer?


texts: Rear light on vintage motorcycle 6 V split to 5 V

texts:
I have a 6 volt vintage motorcycle. With it being a 1920s motorbike, there was no need for a brake light to be attached/fitted by law just a rear light. However I am not comfortable with this and I put my arm out and swing it around to warn people that I'm slowing down. But people still get annoyed and flip fingers and some want to fight me, because nobody knows nowadays what hand signals are.
The problem I have is I don't want to destroy the appearance and remove the old light or fit light boards etc. I want to keep it aesthetically pleasing for the rivet counters.
The light currently fitted is a 6 V single-element bulb and no way of fitting a dual-element due to the size of the fittings.
I was thinking of doing the standard rear brake switch earth etc, but then if I had to put the rear light on for some reason, then the brake light would not glow brighter.
My electrical engineering is pretty poor I'm afraid. My question is: Can I have one live wire going to the light and say lower the voltage by say 1 or 2 V, yes dim but viable? And then 6 V by the brake switch earth, so it glows brighter when pressed. However how would I stop it feeding full power and stop it bleeding the circuits together etc? Is there a piece of kit that will split the live wires? I could then hide the box under the seat, as long as it's not too big.


texts: Common term for Resistance and Conductance?

texts: Simple question; Impedance and Admittance are complementary quantities, and can be described by the common term "Immittance". Likewise Resistance and Conductance are complimentary quantities, do we have a word to describe both of these, like immitance but for resistance/conductance?


texts: Meaning of potentiometer torque measurements

texts:
I've got a Chinese pot datasheet, and the rotational torque is listed as "20~200gf.cm".

This Bourns datasheet lists

  Rotational Torque ............. 10 to 150 gf-cm

Why such a wide range?  Is this a tolerance issue, or is it something like the difference between slip and stick friction?


texts: Is additional isolation needed for inverter control circuitry?

texts:
I'm currently setting up a PV island system. Electricity is stored in two parallel 12V batteries which is then fed into a 300W 230V inverter. The load connected to the inverter consists out of several industrial LED lamps which can be controlled over DALI. An additional DALI-controller is used, which dimms the lamps over a simple 0-10V interface. The inverter also has a two pin connector exposed which can be used to manually shut it off.
I'm in the process of developing a microcontroller based system which controls the inverter over the remote pins and also the LED lamps.
It is clear to me that the secondary side (230V) is galvanically isolated from the primary side (12V) through the inverter's transformer.
However, I see two options on how to connect my circuitry:

Use digital isolators for communication with the DALI controller and an additional SELV 24V power supply plugged in to the 230V side. This ensures that both sides stay isolated.
Directly drive the DALI controller without isolation. This connects the 12V side with the ELV side of the DALI bus. It seems that the DALI lines only have basic isolation.

With normal mains AC, I see the risk of having 230V AC on the DALI lines in case of a fault which can lead to damage and/or shock. But I'm not sure if that is a risk in my inverter system.
What isolation (if any) would you recommend in this situation?
Edit: Added Diagram


texts: Noise of an amplifier due to power supply current ratings?

texts:
I dont have the details of the system such as diagrams schematics. So this will be a big picture question.

I have a system where a 4 gauge transducers are connected to an amplifier box. Amplifier box also supplies power to the transducers.
Amplifier box is supplied by 12V power supply.
The problem was, at the output I observe around 25mV 1Hz square wave noise on outputs. I tried with different 12V power supplies one was 1A rated I had the same issue.

So I sent the system back to the supplier and they examined the same setup didn't observe this noise.

The only difference is that we use different 12V power supply for the amplifier. And in US they use 60Hz AC mains and we use 50Hz(I don't think this has any effect though).

I just checked the manual again and it says the power supply recommended for this amplifier is 12V and 2A.

Can this be the reason for a 25mV square-wave noise.
Would using lets say 12V 1A power supply cause such issue instead of a recommended 12V 2A power supply?

Since the only difference between the setups is the power supply they use I couldn't find any other reason for the source of this type of noise.


texts: What happens if an AC voltage is applied to a battery?

texts:
Today I was checking the voltage between charging terminals going to the battery of emergency lantern using a multimeter.

The multimeter showed a DC voltage of 9V and an AC voltage of 4V.

Could this AC voltage have damaged by old battery?

The DC voltage while being measured was not constant and the decimal part was changing in a cyclic pattern.

I only saw 3 diodes on the board. Is this a half-wave rectifier and is the multimeter mistakingly showing the ripple of half-wave as an AC voltage.

Please see the image of the circuit.


texts: Is there any fixed relation among the operating frequency, diameter of dish-antenna parabolic reflector and the wave-guide (LNB) dimension? What are the best design principles of such antenna? Any help would be appreciated!


texts: How was physical design verification accomplished before CAD?

texts:
I'm reading a history of EDA for ASICs because I'm curious about how older ICs were mass-produced.

The article explicitly mentions that in the early 1970's, SPICE was used to simulate circuit behavior, and cut rubylith was laid out to ensure that the ASIC design matched the schematic correctly (layout versus schematic):

  What we now know as physical design verification consisted of taking flatbed plots of the layouts, pinning them on the wall or laying them on a light table, and having people try to find errors. Hence, physical verification was one of the first businesses to be adopted in the emerging custom design space (see "The More Things Change, The More They Stay The Same,").

However, the article doesn't really go into how designers ensured that ASIC features such as gates, would work correctly when the layout was shrunk to create a mask. Assuming an ASIC mask mistake was comparatively expensive in the past as it is today, what techniques were used to minimize the risk of a defective mask due to improper physical dimensions of features, such as a gate?

Considering geometry is important for an ASIC, were predictions of field strength using Maxwell's equations typically used (analogous to a 2.5D field solver for PCBs today), or were simple transistor models based on length and width sufficient? Or were physical dimension tolerances sufficiently large as to not be a significant source of error during manual layout?

To reduce the scope of the question, let's assume digital ASICs of the era such as TTL or 6502.


texts: Resetting reset to zero after one clock cycle in verilog

texts:
I'm having trouble setting the Start(reset) to zero after being high for one clock edge. I've searched online and tried different ways of writing the clock, but what is puzzling to me is that when I set Start as 1, the clock does not toggle like it should. It is as if Start being high is blocking the execution of the clock code. Here it is:

initial begin
    Clock = 0;
    Start = 1'b1;
    forever begin
    #20 Clock = ~Clock;
    end
end

initial begin
    @(negedge Clock);
    Start = 1'b0;
    @(negedge Start);
    X = 3'd5;
end

My output waveform will look like that this:

Then, if I set the code to be as such:

initial begin
    Clock = 0;
    Start = 1'b1;
    #20
    Start = 1'b0;
    forever begin
    #20 Clock = ~Clock;
    end
end

initial begin
    @(negedge Start);
     X = 3'd5;
end

I'll get the output waveform in the pic below. I don't want that though. I want the clock to be doing its normal pulses independently of Start changing. How do I achieve that?


texts: When to use a heatsink for a voltage regulator?

texts: Sometimes in small projects Im using voltage regulators with outputs 8V or 5V such as LM7805. Power is I*V but Im wondering when really a heatsink is needed. Sometimes the current flow from the regulator output is 1mA but in an other project 20mA or more. Is there a rule of thumb for when to concern about heating and considering to use a heatsink? Consider operating time is 12 hours.


texts: Need some help learning to make my own parts in Eagle

texts:
I am extremely new to using Eagle (or creating circuits in general). I've been searching around online for tutorials on making your own parts in eagle.  However, I still have a few questions and I was hoping to get some clarification.

For reference, I've been trying to build this 28-pin IC socket:

I was unable to find one of these in the default eagle libraries, so I am trying to make my own.

As far as I can tell, making a part consists of three parts: making the symbol, making the device, and making the package.  I know that the symbol is simply what appears in the schematic and doesn't really have to exactly match the size or shape of the real part.  I don't, however, really understand what the package and device are.  I know they relate to the real part id and the size and shape of the part on the board.  Can I please get some clarification on what the package and device correspond to and why I need to make them?

Also, when looking for parts using the design link, I often struggle to find the part I'm looking for.  Is there a way to view the database eagle's design link is using in a browser rather than in that dialog box?  It would make things much easier for me when looking for a specific part.


texts: Can I use unregulated power supply for LCD display backlight LED?

texts:
I am designing a PCB for a university project that will include an LCD display which is powered by 3.3VDC regulated supply. Unfortunately this display has backlight LEDs in series that have total forward voltage of 6.4 volts. My board includes 3.3VDC and 5VDC regulated power supplies which unfortunately cannot satisfy the required 6.4VDC. I am hesitating if I can use my 24VDC unregulated power supply for this purpose. The power supply would have a 2 volts voltage ripple(100Hz) with a max. peak of around 24 volts. I was thinking if it would be viable to put a resistor in series and supply the Display LEDs with this PSU.

Is this unregulated voltage going to present a problem for the display LEDs or the display in general?
Will the voltage ripple be visible through the LCD display brightness?
Do you have an advice for a better approach considering the above mentioned PSUs?


texts:
I recently acquired an early model Vic 20 computer but don't have a power supply for it and thought I might be able to make one.  The Vic 20 is the early model with the two pin AC connector - not the later model DIN plug.

From what I've read it needs 9VAC at about 3A.  I'm in Australia where mains is 240VAC, so I'm looking at this transformer:

http://jaycar.com.au/productView.asp?ID=MM2014&keywords=mains+transformer&form=KEYWORD.

It doesn't say on that site but in their dead-tree catalog it's got two sets out secondary outputs each multi-tapped 0->9V->12V, 2.5A each.

Since I've not done much with mains, just want to check somethings:

Wiring the two secondary 0v + 9v outputs in parallel will give 5A output - enough to power the Vic and some accessories.
Will I need a fuse on the mains side? They recommend one on the page so I presume so.
What sort of case would you recommend for something like this - it's just the transformer and fuse, with a mains and 9VAC leads coming out.  Should the case be ventilated, plastic, metal, how to best mount the transformer etc...
Have I missed anything?


texts:
Very often I encounter some opamps are titled as high-speed in their datasheets such as this one.

What parameters make an opamp high speed? What is meant by that? Is that something related to opamp bandwidth or slew rate? And what is the criteria in that case quantitatively?


texts:
I am designing a small and compact measurement device housing an arduino and breadboard.

I have a number of small electronic PCB's and components I would like to house securely inside and I was wondering if people can recommend ways to secure them so they don't rattle about inside.

The case is made from plastic and 3D printed.

I want the components to be removable in the case of fault or replacing, so I was considering velcro as an option.

Any better ideas would be much appreciated.


texts: USB host requesting invalid descriptor length

texts:
Monitoring the traffic to my USB HS device, there is a strange transfer. Host is 64 bit Ubuntu 13.10.

The Device Descriptor is always 18 bytes, by USB specification.
On each enumeration, the host sends 3 Get Descriptor: Device requests with wLength fields of 18, 8 and 18.
Wireshark complains that the second response, in which the device correctly chops the first 8 bytes from the Device Descriptor and sends them, is a Malformed packet.

The device eventually enumerates successfully, but does not appear in the sound menu to stream audio to.

The same device, under 64 bit Windows, again enumerates correctly, but reposts
    Error (10): The device cannot start.

So my question is: Is the described situation in the bullet-points abnormal, or is Wireshark wrong?


texts: How to convert +5V power source to +/-5V power source

texts:
To supply op-amp 1, I need a power supply voltage of +2.5V and -2.5V. To supply op-amp 2, I need a power supply voltage of +4V and -1V. The outgoing signal from the op-amp stage will be fed into an ADC, so the rails have to be stable. I thought about using a DC to DC converter, but I could not find one with a positive and negative output voltage.

How can I convert a 5V source to a bipolar voltage source?

I have this recommended circuit from Texas Instruments, where THS4509 is op-amp 2. They recommend a supply voltage of +4V and -1V to set Vcm as 1.5V.

Image source: Texas Instruments ADS612x 12-Bit ADC family datasheet
My signal source (Vs) will be op-amp 1, the output signal from op-amp 1 can be between +1V and -1V.

By the way, what do I need for the resistors Rs and Rt?


texts: Using JTAG to "explore" a board without damaging it?

texts:
I have one Amontec JTAGKey2 Generic USB JTAG cable interface. What I am looking for is some explanation of how to "explore" a device of which I don't know all exact details, but for which I have a BSDL file that fits almost. I cannot damage the device, which is why I'm trying to be extra-cautious.

Is this even possible or am I looking at the wrong technology for the task below?:

In general my first main interest is to poke around in memory and perhaps change a few bytes.
Next would be flashing a component connected to the JTAG chain.

Right now I am locked out of the board because the "environment" of the (vendor-custom) boot loader is invalid and the boot loader simply ends up segfaulting without letting me into the interactive mode.

The board for which I only have very little documentation of a newer hardware revision (unfortunately under NDA) than I have is from RMI and can be used as a standalone network card or hosted as a PCI-X (not PCI Express!) board. The JTAG connector is a standard MIPS one and according to the vendor complies to the voltage and pinouts documented for MIPS.

The vendor only documents and supports use of particular (and rather expensive) JTAG probes. Amontec's JTAGkey2 isn't one of them.


texts: Why DC spurs are present in FFT plot of ADC

texts: While reading about coherent and non-coherent sampling of ADCs in general, I read that we need to neglect first 6 DC bins in the output FFT plot while calculating parameters like SNR, SFDR etc. for the ADC. I had thought that DC bins correspond to the spurs introduced by the power supply source. Is there any reason why 6 bins in particular is being omitted?


texts:
I while a ago I saw a circuit in a datasheet that automatically cleared a 74xx164 shift register on power-up. I don't exactly remember which logic series it was (might have been LS or HC), and the reset circuit was basically just a capacitor and a resistor which generated a reset pulse when power was applied to the circuit. I don't remember if it contained any further components, and I cannot find that datasheet anymore (because I didn't really pay attention to the circuit at that time).

Does anyone here remember having seen that circuit, which datasheet it is in, or possibly even used it? I have looked at RC reset pulse generators on the web, but I'm not sure if they are the same thing I have seen in the datasheet.

I'm basically asking for advice on how to build a reset circuit for a 74xx164.


texts:
So I have this LCD lying around, and I was wondering, is there any way to interface it with a PC? Be it USB, HDMI, VGA, planning to use an old PC with it.

I don't need to use the touch controller, only the LCD itself.

LCD Pinout: Pinout


texts: Impact of permanent magnet on component storage

texts:
This may sound like a silly question, but it got me thinking.

Apart from my lab at work, I have an electronic workbench at home. Most of my components are stored in small, plastic cylindrical jars (imagine the ones used for storing medical pills, something like that). I have a lot of those so I store all my resistors, capacitors and small package ICs in those containers. The problem is that the containers are all around the place, and even keeping them in a boxes makes it hard to find anything.

So my idea was to glue a small permanent magnet at the bottom of each jar and then put them on a metal surface (like a white board, or just a metal bar mounted on the wall).

However I was wondering if the magnet would have an impact on the components inside the jars. I had cases where transistor leads were attracted by magnets (no idea why, since they are supposed to be copper). I was about other drawbacks of such a solution, like maybe the components could get magnetised and would attract each other when assembling a PCB - that would be annoying.

So... Could you share your concerns regarding such a solution? Should I worry about the magnetic field?


texts:
I don't want to use an FPGA.

I need to quickly put together a prototype that will relay DCMI data (small resolution camera sensor) to DS90CR285. Here performance doesn't matter that much – later it will be deployed on an FPGA anyway. However before that I wanted to fiddle around with this LVDS driver.

In your opinion is it possible to use FSMC/FMC hardware inside STM32F4 series chips to drive DS90CR285 or is it a complete waste of time?

The way I see it - the chip can be treated as an LCD display with some customisations on the way.

UPD:
LVDS must comply with Camera Link protocol in base configuration. Transfers are 12-bit so the overall speed is 115200 Bps.

My question is for those who are familiar with STM's FSMC/FMC behaviour when used in this fashion.

DS90CR285 datasheet

STM32F427 datasheet


texts: Invensense MPU9150 Accelerometer Raw Values Even

texts:
I've been working on pulling data from an MPU-9150 for a data filtering project, and I ran into a issue that I'm not sure of the cause.

When I set the accelerometer to ±2g or ±4g range, all the raw values are even (i.e. evenly divisible by 2). However, if I set the range to ±8g or ±16g, the values can be even or odd.

I've been in touch with Invensense tech support because of a different issue of spiky data distributions, however they didn't think there should be a reason the values should be only even. I've run into this issue using my own code as well as Jeff Rowberg's I2Cdev MPU-9150 library.

What I'm looking for is some more opinions on what might be the reason behind this as I wait to hear back from Invensense. I'm far from an expert on MEMS architecture, and there are tons of computer science nuances that I'm sure I'm unfamiliar with, but I'd like to hear if people have an idea on why I'm getting what seems like an anomaly.

Please let me know if I can provide more information.

Thanks,

MPU-9150 Datasheet


texts: A fully charged 3.2 V DC cell used to power a 3.5 V DC light string gets discharged in 2 hours

texts:
A light string, normally powered by a 120 VAC to 3.5 V DC 800 mA power supply, when connected to a single 3.2VDC cell (LiFePo4 26650 3300 mAh), was bright at first, then dimmed and went out within 2 hours.
Would a series resistor extend the discharge time? If yes, what should its value be?


texts: Hardware that can spoof mA usage or cause it

texts:
I have a device that is expecting to trigger when the TV turns on/off except I can't plug the TV directly into it. I have a WeMo smart plug which is meant to spoof the TV turning on/off however, I need it to pull enough of a significant draw of power to trigger the device.
Basically, I'm looking for something to plug into the WeMo that is designed to be inefficient OR a device that can spoof mA usage when it's on. Not sure if spoofing mA usage is possible without actually spending electricity but I figure I'd ask.
I tried plugging in a usb power bank which was good until it was fully charged. I'd then need to discharge it but wasting energy somewhere else (and it's very inconvenient to remove from where I need to put it). I also tried plugging into an old phone and using an app to cause the phone to require more power but I'm afraid of the phone getting too hot.
I'm thinking maybe there's a small circuit to trick a usb plug to think it's always needing power?


texts: Driving a linear actuator from a home automation system

texts:
I am not exactly an expert into electrical engineering. I have a Linak LA12 IC linear actuator, and am trying to drive the motor from two outputs on my home automation system. The home automation system has a 24V DC (max 500mA) output module. The motor will reverse direction as the current is reversed.

The actuator will drive a mechanism that will raise and lower a projector hidden in a compartment in the ceiling.

Here is my planned circuit.

The power source on the left is a 24V 5A laptop power brick, and the power source and switches in the middle emulates the 24V 500mA outputs on my home automation system.

I have been told that there is a potentially a problem with this circuit if the power brick is grounded internally. I do not understand what this issue is or how to solve it.

My question is: do you see any issues with this circuit?


texts: Help finding PWM IC with marking on device 'GLS'. Package of device is SOT23 - 6

texts:
I am trying to do some reverse engineering on 12V DC wall adapter where I found this 6 pin PWM IC. I am unable to find any of it's details on google.
So requesting if anyone could help me in finding the device name.


texts:
If these 2 signals, that form this duplex, have ranges of 15-30 [kHz] and 30-45 [kHz] using:

\$NoiseFloor_{dBm} =10\log _{10}(k\times T_{0}\times 1000)+NF+10\log _{10}(BW)\$

and if \$K,T,F\$ and \$\Delta f\$ are given, only thing left to figure out is the \$BW\$ (bandwidth). Is the \$ BW=2(\Delta f+f_{m})\$ where \$f_{m}=2\times 15=30 [kHz]\$ correct formula for the bandwidth of this duplex?


texts: Timing specifications: can a spec be converted from units of +/- ms to parts per million?

texts:
I have a test specification that requires time base uncertainty of +/- X ppm or less.  I understand that ppm is a common way to specify crystal accuracy.  But in the performance specification for my measurement equipment they are specifying time base accuracies in terms of +/- Y ms.

Is there a method to convert from one to the other?

For example, is there a way to convert the following accuracy specification in terms of ppm?

Pulse Width:
Range: 1 ms to 50 ms
Accuracy: ± 0.1 ms

Note, I cannot find an actual reference clock rate in the entire equipment performance specification.


texts:
I'm designing an audio circuit running on ±15V supplies, which has a need for precision +12V and -5V rails. These must source (from 12V) and sink (from -5V) up to ~20mA to power a CEM3340 oscillator and some ancillary components. Absolute precision of these +12V and -5V supplies is not critical (±1% would be OK) but I would like to minimise temperature dependence as far as possible, within a maximum budget of around $3. Load regulation needs to be good, as the CEM3340 current draw will vary with time across the oscillation cycle.

The circuit already uses several OPA1679 op-amps (which can source/sink over 20mA) and a 5V precision reference. So one solution seemed to be using two amplifiers from an OPA1679 in straightforward non-inverting and inverting configurations to give +12V and -5V from the existing 5V reference.

Is using an op-amp to provide the power rails in this way sensible? If so,
How should I make sure that the new power rails are properly decoupled? I understand that putting decoupling capacitors across the new op-amp outputs may cause instability, but don't know how to predict or mitigate this.

If op-amp outputs are not sensible here, what would be the best strategy for getting these power rails?


texts: Measuring individual cell voltages in a series cells Battery

texts:
I'm making a 600V battery, and I'm trying to design a Battery Monitoring system, that measures (and keeps log of) each cell's voltage turn by turn, in a series configuration of 162 lithium cells.
162 cells x 3.6 volts per cell = 600V battery.
A simple Arduino Analog input reads each cell in sequence, here's how:
Each two cells (+ve to -ve) connection has a third wire going to an optocoupler collector and its emitter is going to either of two common lines. All of these 162 OCs are switched by a 162 bit shift register.
The two common lines go to Arduino Analog Inputs (A0) and (A1).

Keeping all OCs off, when I switch on only 1st two OCs, (O1 and O2) Cell 1 (C1)'s +ve comes to A1 via Line 1 and -ve comes to A0 via Line 2.
Keeping A0 digitally Low, thus making it GND, can read voltage of C1 at A1.
Then switch on only OC3 and OC4 to read C3's Voltage at A1, and so on for C5, C7... C161.
Then digital low at A1 and read at A0 for C2, C4,... C162.

Should this work?


texts:
I am attempting to design a system that charges a 6 cell 1800 mAh NIMH R/C car battery wirelessly with the DS2715 charge controller by Maxim. I am trying to modify their linear charging design for a 6 cell battery. In the data sheet they specify the circuit for charging a 3 cell pack (in series) linearly (with a 6 V supply), and I have built the circuit accordingly.

The only info in the data sheet regarding changing the cell count is the voltage divider on the Vbat pin for detecting a single cell's voltage. I assume that for charging 6 cells I would double the supply voltage for 12 volts? I know that the IRF can handle this change but am unsure about the other components and do not want to damage the IC.

When I supply the circuit with 6 Volts and use the original resistive divider for 3 cells, the LED is off (as it is supposed to be with no battery connected). But, when I use the 6 cell resistive divider and supply 6 V the LED flashes at 4 Hz indicating that there was a fault. I am assuming this is because the circuit really does need 12 V. I have a LED that is suited for 12 V on the way but wanted to see if anyone has used this IC for a similar design and could offer some insight.

I have contacted Maxim for support but they have not gotten back with me yet. Thanks in advance.

Part link: https://www.maximintegrated.com/en/products/power/battery-management/DS2715.html

Datasheet: https://datasheets.maximintegrated.com/en/ds/DS2715.pdf


texts:
I am programming an Altera Cyclone IV using Verilog and Quartus II. In my design, I would like to use both edges of a clock so that I can do clock division by an odd factor with a 50% duty cycle. Here is a snippet of my code:

  always @(posedge low_jitter_clock_i or negedge low_jitter_clock_i or posedge reset_i) begin
    if(reset_i) begin
      fixed_clock <= 1'b0;
      divider_dummy <= 'b0;
    end else begin
      fixed_clock <= fixed_clock_next;
      divider_dummy <= divider_dummy_next;
    end
  end

Now when I compile this, Quartus II throws the following error:

  Verilog HDL Always Construct error at adc_clocking.v(83): event
  control cannot test for both positive and negative edges of variable
  "low_jitter_clock_i"

How can I use both the positive and negative edge of a given clock in my design?


texts: Should I wire my CNC limit switches as NC or NO?

texts:
I built a CNC router about a year back and have had intermittent limit switch triggering for a good while.
After doing everything I could to remove any EM interference from the system (run the signals through optocouplers with isolated PSUs, shield all wires, star connect all earths, etc. etc.) I then got to the point where I gave up as it only triggered when doing heavier cutting, so I just ran the machine at half feed and got on with my day.
But I had a brainwave the other day and realised that it might just be mechanical vibration causing the intermittent triggering rather than interference... So I got to testing (tapping each switch with the back of a screwdriver) and it seemed my theory was right!
At this point, my switches are NC microswitches, so I thought I'd get some slightly better switches more suited (they're still cheap but they at least they're called limit switches).
But, same problem, when I tap them, they trigger. Then I realised that because they're NC, it only needs to slightly break contact to trigger (whereas if they were NO, the contact would have to move the entire way to the other contact inside the switch). So I tested this by wiring as NO and it seemed that tapping the switch didn't cause it to trigger anymore.
But the reason I chose to wire as NC in the first place, was because if they fail, they would trigger (and apparently they're less prone to EM interference).
So, here's my 2 options (sorry about the backstory, I thought it might help):
Option 1:
Remain as NC and buy high quality switches? (The problem is the switches I've seen are easily £50 each and I need 6... The switches I currently have about £1.50 each...
Option 2:
Rewire as NO, (This solves the mechanical shock issue, but has no failsafe if they go wrong). The only other issue is that I also have a NC touch sensor which would be in series with one of these NO switches, so I would have to invert that somehow, and have a NC and NO switch in series which I don't know how to do.
Thanks in advance and sorry for the long explanation but more often than not, when you explain the whole problem, people sometimes come up with a much better solution that I hadn't even considered!


texts: How do I put in a volume control on this wired phone headphone set?

texts:
I have this headset which I use with a cordless handset. The problem is the volume is way too loud even if I turn it down all the way on the cordless handset. There are no controls on the headset. I really like this headset, it's just too loud. I wish there was a volume control on it. How can I make this happen?

Equipment list:
Uniden Phone –  model D3580 (standard 2.5 mm telephone headset)
Plantronics headset which uses the standard 2.5 mm telephone headset

I assume I could buy a volume control (Potentiometer) but I don't know which one. How do I match it up to the specs? Remember, I only want to turn this down I don't need to make it louder so no amplification is needed.

What parts do I need exactly? How should this he assembled? Is it required I use a soldering iron or can this be done another way I'm not aware of? Thanks!


texts: How is a memory location accessed by random access?

texts:
This is a comment that I saw in another forum:
Like any other memory storage, it's divided into smaller units. These units can contain data individually or can be treated as a big single block of memory. So suppose your RAM is divided into 512 individual blocks. You need to access the 199th block. So a sequential approach is to start from one end of the memory and move towards the desired block. So if you started at the 1st block, you need to pass through 1,2,3,4,5,……,197,198 blocks before reaching the desired block no. 199. But Random Access means that instead of passing through all the blocks present between you and the destination, You can directly access the desired block. Thus the time required to read any particular block remains constant regard less of its number, that is its relative position in the chip. Hence, you can access any block in same amount of time as any other block. For example, you can access any of the 512 blocks in exactly same amount of time.
So, starting from that statement, I would like to know exactly how the RAM locates, for example, position 1000 (or any 'position X' that the CPU has indicated) in the same time that it can locate position 1.
I imagine it as a matrix but I can't figure out how it can access exactly to position 1000 without having to go through the other positions. How is this position calculated exactly?
In conclusion, I would like to know how to directly access a memory location without going through the other locations.
Thank you very much in advance.


texts: What is the ground-source voltage of this current mirror?

texts:
In Neamen's microelectronic book, there's a problem using this current mirror

There is a 5V DC voltage source above the current source.
The reference current is 250 microAmp.
The threshold voltage is 1V.
The transistors are matching (W/L is 3 for both).
The Kn' is 80 microAmp/volts squared.

Also, Instead of ground, there's a -5V DC voltage.

What is the VGS of the two transistors?

from the figure, it seems that the Vgs should be 10V. Since assuming there's no voltage drop acroos the current source, V+ - V- = Vgs. However, getting the Vgs from the drain current equation

yields a 2.44V.

Which one is corrent and why?

EDIT: And no this is not a homework question.


texts: 24V proximitiy switch, NPN transistor, Arduino interrupt input

texts:
I build circuit which take proximitiy sensor as input to circuit (24V). With this 24V we switch on and off NPN transistor.

On the side is Arduino with interrupt enable when pin is LOW. So I need circuit that convert 24V pulses to 0V and 5V pulse for Arduino input.
Switching speed is 3kHz.

So we can take 24V and with NPN transistor turn it ON/OFF?.

This is circuit in multisim.

and results:

Yellow: Input signal (signal generator)

Blue: Voltage base of the transistor
Violet: Output NPN Voltage
As input is

Why is there so much spikes? Should i use different circuit for this purpose?


texts: Is there an open source IO-Link stack available?

texts:
I have been looking at designing a solution around an IO-link master.

Does the IO-link Consortium allow for open source implentations of both the master and slave?

The documents online seem to give enough info to implement at least a basic feature set?

Are there open source implentations or free source code available?


texts: When does I_C be approximately equal to I_E

texts: I have seen in certain problems, they say that $$I_E = I_C$$ by saying that β is very large. I don't understand what can be considered as large β. So, I want to know the range of the values for β for which I can say $$ I_E = I_C $$


texts:
Im using op amps to generate a triangular wave, my ultimate goal will be to power motors using pulse width modulation.
The problem is that the triangle wave is saw toothed instead of symmetrical.
Why is this? what mistake have i made in my circuit?


texts: What is the current flow logic of this NPN configuration

texts:
For a switch i need to put the transistor in cutoff to OFF and saturated for ON as shown in the lecture bellow.
My input is a voltage source i need to control the base current to make the collector current as high as possible ,saturated state.
How do i control the current going into the the base .
how can i see the current mechanism of the circuit bellow?
Thanks.


texts: Cheapest way to wirelessly transmit video

texts:
I'm really big on building RC vehicles. I want to hook up a video camera which can transmit video signals, but don't know what options I have available.

My only requirement is that it has to be as cheap as possible. I care very little about video quality, range (anything greater than 2 meters), frequency, etc. at this point. Of course, if a little bit of extra cash could get me a better setup, I'm all ears.

The other thing is, don't worry about the ground display. I'm still deciding whether I want to use a monitor or video goggles, but I don't need any recommendations for those at the moment.

Thanks.


texts: Is it possible to estimate the execution time of an FPGA design?

texts:
Is it possible to evaluate the "execution" time of an FPGA design?

I think that if you have a design where you only have And, Or, Not, etc. gates, the result only depends on the inputs.

But now with FF-latches there is a timing constraint, isn't it? I mean, for example if you have the following design :

simulate this circuit – Schematic created using CircuitLab

If the input changes, it will takes 3 clock cycles for the output to be updated ?

Knowing that, I have a more complex design in Vivado where I can't count the FF-latches in order to determine the "longest" path. But is there an option or a way to do it ?

Bonus question : does a look-up table operation take one clock cycle to be completed ?


texts:
manufacturer number (Mill-Max): 855-22-010-10-001101 datasheet (2x5 pins)

Can I directly solder something to the bottom pins ? The manufacturer has some solutions but it requires expensiv tools which I don't want to buy. What could be a good solution ?


texts:
I'm trying to find out the wattage of some bulbs supplied to a company I'm working for.

The product is a set of garden lights (Cheap Chinese) which is 10x small bulbs in parallel, powered by a 12Vac 5A 60VA transformer.
The issue is we seem to be receiving a lot of burned out transformers back, and looking at the bulbs, i think they are more than the rated 5w.

I can remember back to my electronics days with V=IR etc, but all i am able to measure is the un-loaded voltage of the transformer (12.6Vac) and the voltage measured across the bulb is 10.1v.
I cant measure the AC current, or the ON resistance of the bulb.

Is it at all possible to calculate the bulb wattage?


texts: Should every FPGA design include a reset signal?

texts:
I'm designing an adder in VHDL, and I've come across several VHDL designs (not necessarily adders) that include a reset port. My adder has input and output registers. Should all designs include a reset signal? What is the use of this reset?

Edit:

Resetting the carry_out makes sense to me, because some systems would handle that as an exception. What about the input registers and the sum output?


texts: Measuring DC current with Hall Effect sensor over PIC on the same circuit

texts:
Before I begin with my question just so you know I'm not very familiar with electrical engineering so please forgive if I ask some dumb question :)

What I want is to know if I can use Hall Effect sensor (ACS712 for example) to measure DC current pulled from LOAD device.

To be more precise, I want to have my measuring device connected on the same DC source as the LOAD device.

However, I noticed on this module on the left for example that I can put it on the "VCC" wire for example, and "OUT" on the right to my PIC microcontroller and to read voltage there, but can I connect my "measuring device" and "VCC" and "GND" of this sensor as well on the same source in series before the load device, would that current detection be affected with "measuring device" it self?

If the answer is yes, can you please post a scheme how this needs to be wired please.


texts: Limiting current through Zener shunt reference by PNP current source

texts:
I've got an unregulated input voltage of 5V..20V from which I need to drive a shunt reference LM4040 at 3.3V. According to my calculations a shunt resistor of 1.5kOhm would result in a peak current of (20V-3.3V)/1.5kOhm = 11mA and dissipated power of 3.3*11mA=36mW. The current is alsready close to the rated maximum of 15mA. At 5V the a 1.5kOhm shunt will only give around 1.1mA of output current which seems low since the STM32 datasheets states VREF+ current consumption of 500µA but does not state wheter this is for one ADC or all three sampling.

Given these constraints I'm thinking about placing a simple PNP current source in front of the shunt reference to supply a constant 5mA independent of the supply voltage. I also hope to reduce self heating the reference and therefore improve stability.

simulate this circuit – Schematic created using CircuitLab

Does this make sense? Am I missing something, are there gotchas I need to be aware of or is there a better solution?

Admendum

Out of curiosity I simulated the PMOS version of the circuit, which also kind of works. However, I have no clue how to calculate the current. Can someone give a pointer where to start analysis of MOSFET in linear mode?


texts: For remoting 1000Base-T ethernet connector, is it better to remote PHY from magnetics or magnetics from connector?

texts:
I'm in need of remoting the gigabit ethernet connector from the main board to a back end board that has all the other connectors.  I plan on doing this with a high speed board to board connector (Samtec QRF8-026-05.0-L-D-A-GP which has a ground plane and using extra pins to separate the differential pairs), but I don't know if it is less damaging to signal integrity to remote the PHY from the magnetics and have the magnetics in the same board as the connector (built-in magnetics are not an option), or have the magnetics on the main board and remote the connector alone.  This is under 1.5 inches of remoting overall.

One restriction is that the board area in the connector board is very limited.

I know that ideally they should all be on the same board but remoting the connector will help a lot in the overall design of the product.

EDIT:

If at all possible, please explain your answer in terms of the physics involved.


texts: What kind of oscillator should I use for a binary clock?

texts:
I've seen that a lot of clocks use a 32.768KHz crystal.  I'm curious why that is exactly.  I am working on a binary clock project with some 4520 ICs.  I have some 555 timers too, but I want to use a crystal if I can.

I just don't know what would be the most accurate.  I also don't know anything about the configuration.  For instance, does the 32.768KHz need to be used with resistors or capacitors to operate?


texts: I have a closed core with a coil attached to it and metal inside the core. The N is 100, I is 100mA and l = 300mm. I have computed the magnetic field B = (μ0 * μr * N * I) / l. But I have also given area A = 2cm^2 of the core, should I take that into account somehow?


texts:
In a prior question I asked about a truncate function, which hinted that I should try a function with a static return width.

I am trying to combine two vectors x and y by taking the first c bits from x and the remaining x'length - c bits from y. (I assume x and y are of equal range). Therefore I wrote the following function, which again yields an error, this time on the line were I assign result

/*
 Combines two signals by taking bitsFromX bits from x and the rest from y.

 x vector 1 to combine
 y vector 2 to combine, must be of same length as x
 bitsFromX number of bits taken from x
 */
function combine(x: in std_logic_vector; y: in std_logic_vector; bitsFromX: in natural)
return std_logic_vector is
    variable result : std_logic_vector(x'RANGE);
begin
    --assert x'LENGTH= y'LENGTH report "Attempt to combine different length vectors" & lf & "X: " & RANGE'IMAGE(x'RANGE) & "Y: " & RANGE'IMAGE(y'RANGE);
    result := x(x'LEFT downto x'LEFT-bitsFromX+1) & y(y'LEFT-bitsFromX downto y'RIGHT);
    return result;
end function;

The error message (from synplify) is:

  Expecting constant expression

I can work arround this by using two assignments:

result(x'LEFT downto x'LEFT-bitsFromX+1) := x(x'LEFT downto x'LEFT-bitsFromX+1);
result(y'LEFT-bitsFromX downto y'RIGHT)  := y(y'LEFT-bitsFromX downto y'RIGHT);

and would like to understand why this is so? (It a ppears to me that it is the second time I make the same mistake, because I do not understand the reason yet).

As a Bonus: How do I report the result of x'RANGE, to_string(x'RANGE) and RANGE'IMAGE(x'RANGE) don't work for me.


texts: Why are the power pins on an L298 H-Bridge named "Vss" & "Vs"

texts: I understand that Vs is where the H-Bridge gets it's power for driving the motors and that Vss is used for driving the logic, and they both sink to a common ground named "GND". My question is why are they named "Vss" and "Vs" instead of "Vdd" and "Vd" like in any other chip where Vdd is the positive voltage input. Thanks


texts:
Today while installing a 12v LED strip on my windows with the power adapter plugged but the LED turned off, I noticed the led that I pushed down against the wall got turned on partially. It wasn't right. My finger shouldn't have enough resistance to turn on those led with 12v. Right away, I tested the DC adapter output line with a 90-1000vac surveyor and found out that the 12vdc line from the DC adapter carries a high voltage AC. When testing with a meter, it measures about  12vdc, and unstable AC range from 38-0Vac. ( properly higher AC voltage, since my meter may not be fast enough.)

1, Is it safe to use this power adapter? ( It powers up the LED strip fine. I have also found a 5V usb charger that carries a HIGH voltage AC before, of which I discarded right away.)

2, What is the cause of this HIGH voltage AC? ( Is it because it's not isolated? or it's not filtered properly at the output end? I can't open the case, as it's sealed completely with no screws. )


texts: What value resistor to add, so my motor provides the correct amount of power?

texts:
Motor Specs
&
Circuit Diagram

I'm an Aero student with virtually no electronics knowledge. I'm trying to figure out what value resistor to add to this circuit, so my motor provides the correct amount of power.

The motor is usually part of a small quadcopter drone. The battery used is 3.7 V, 650 mAh. When this battery was powering the whole drone (lights, 4 motors etc) the meter readings from a single motor at full power were 3.203 V and 1.88 A.

I have now separated one motor in order to build the simple circuit (pictured) just to measure RPM. (This is a very small part of my project. I am aware of more sophisticated methods to vary motor output, but I am using a variable resistor as the results only need to be rough). This circuit will use the same battery as before.

I would like to add a resistor to this circuit, so that when the variable resistor is turned to zero, the motor cannot output any more power than it was before. Then, when the variable resistor is increased, it eventually stops the motor.

My question is: What values of resistance do this normal and variable resistor have to be?


texts: Need help picking components for a stir plate

texts:
I  was going to make a stir plate to grow yeast for brewing beer. It involves using some type of housing (cigar box, wooden box), wiring some DC voltage to a switch, to a dimmer controller, to a PC fan inside the box. On the center of the fan, you glue magnets. When the magnets rotate, that rotates a magnetic bar inside your flask of yeast that is sitting on top of the box. It is a pretty common DIY project.

My trouble is, I'm not sure what I should be using here. I was planning on getting a 12 volt DC adapter and wiring that to a simple toggle switch.  But, I'd also like to add a DC speed control to the motor.  Can someone provide me guidance to get me started down that path?


texts: TFT Monitor output is blurry and weird looking - but OSD works fine

texts:
I don't really know how to describe what happened to my monitor, but I made a small video here.

In summary, the output of the monitor is all garbled, but still there (not dead) - but the OSD works fine.

I have some knowledge of electronics - so I opened it up, checked the capacitors, didn't find anyone gone bad - but I'll check again, might have missed something.

Any pointers as to how could this happen, and where should I focus my investigation? I guess it's something related to the VGA input, but what could it be? (So I should check only the vga board, not the power one?)

I should note that I have another, identical monitor (it was a part of a dual-display setup): If I remove the faulty monitor and connect the good one, everything is fine - so it can't be the PC or the VGA or the cable, something has gone wrong in this particular monitor.


texts: What should the minimum voltage rating of replacement power resistors be?

texts:
I'm looking for four power resistors of the same type to replace R87, R88, R89, and R90 in the POWER AMP section of the amplifier of Klipsch SW-12 subwoofer shown below:

What should the minimum voltage rating of the following new resistors be?

Choice 1:

5W 1.5K ohm

Choice 2:

5W 1K ohm

Choice 3:

7W 1k ohm

Choice 4:

7W 750 ohm

Choices 1-3 all have their voltage rating listed (350V - 500V), but I can't find the voltage rating for Choice 4:

http://www.newark.com/multicomp/mcprm07wjp751b00/metal-film-resistor-750-ohm-7w/dp/16R1987?exaMfpn=true&categoryId=&searchRef=SearchLookAhead&searchView=table&iscrfnonsku=false

Datasheet:

http://www.farnell.com/datasheets/1679919.pdf?_ga=1.219978905.1878132867.1486504283

If I can't find the voltage rating for Choice 4, should I drop it from my list of choices for the replacement resistors?

[A picture showing R88 and R90 with four other white resistors: Added 2/13/17]

There's a similar-looking row of six white resistors on the other side of the amp, too (bottom in the picture).

[Added 2/13/17]

I received a reply from a US distributor of the Choice 4 resistor:

Received: Mon, Feb 13, 2017 9:33 am
Subject: MCPRM07WJP751B00

Hi

The max voltage rating is 500v.  I don’t have a data sheet to send but the product manager was able to contact the mfg to get the voltage.

Have a nice day.

. . . . . . . . . . .

[Added 2/14/17]

This is the resistor's listing that prompted me to ask a question about voltage rating for resistors:

http://www.newark.com/cgs-te-connectivity/sbche61k0j/wirewound-resistor-1kohm-7w-5/dp/16R6555

I hadn't been able to find it until this morning.


texts: Arduino as full fledged keyboard controller?

texts:
I am considering connecting a ThinkPad X4x keyboard to a PC, using a programmable KeyWarrior keyboard controller in between the keyboard's ribbon cable and the USB cable to connect it to the PC. Not being an electronics guy, I checked back in the KeyWarrior forum and was told that this should work. The necessary parts are all easy to obtain, and I know how to use a soldering iron. ;-)

Anyway, everywhere I hear Arduino, and it would probably be worthwhile to learn about this universal microcontroller. Would it be possible to replace the KeyWarrior solution by an Arduino solution?

Note that the KeyWarrior16 supports two layers, for the FN key on the keyboard.

I now also opened a thread in the Arduino forum.


texts: Why are boost/buck converters never fully integrated/all-in-one?

texts:
Moving from small arduino applications to higher-power applications for work, I've had to switch from using simple linear regulators to switching boost/buck converters any time a different voltage to what is available is required. This has been much more of a learning curve than I anticipated; things like switching frequency, inductance and capacitance values all need to be taken into account, and there are almost always several external components (for example, the inductor) required for the converter to function.

My question is, why are these additional components almost always external? I'm not complaining, I've been learning a fair bit from the switch and it's not too bad a curve, I'm just curious as to why there seem to be no plug-and-play ICs (at least not that I've found for 24V, 3A output, correct me if I'm wrong) like there are for smaller linear regulators.

My guess would be too much heat generated?


texts: control systems - What is \$\det[sI-A]\$?

texts:
I am reading the 12th edition of "Modern Control Systems" from Richard C. Dorf and Robert H. Bishop which is about control systems.

It is not totally clear to me how the author came up with the formula in the problem's solution I describe below.

The problem:

The solution:

I read the theory from the corresponding chapter, but I don't totally understand how they come up with \$\det[sI-A]\$. I found in the theory that \$[sI-A]^{-1}= \Phi\$ where \$\Phi\$ is the matrix exponential function
that describes the unforced response of the system. Yet here they modify it slightly and compute the determinant rather than the inverse. Why? How did they come up with this solution?


texts: Is there a USB interface for a RadioShack 22-812 Digital multimeter?

texts:
I have a RadioShack 22-812 Digital Multimeter which has a Serial PC Interface.

Is there any sort of adapter that I can use to connect it to a computer's USB port instead of using the Serial Port?


texts: Is there a technical reason why most of desktop fans only have fixed speeds?

texts:
The absolute majority of desktop fans only allow the choice of three speeds, leaving no option for the case when the lowest speed is still too fast. This is true even for expensive models that feature OLED displays, remote controls and other extras that seem much less required.

Is this just a design decision, or there is some technical reason that makes smooth speed adjustment difficult to implement?


texts: What is the point of inverted Q and inverted I on a receiver? Specifically on FMCW radar applications?


texts: Mounting finned flat-base heat-sink with no tabs or screw-holes

texts:
The heat sink has a flat base with no tabs or holes.

How is it supposed to be mounted on a PCB?

Wire brackets soldered to the PCB come to mind but then how does one ensure there's enough pressure between the heat sink and the PCB for good heat conduction?


texts: Are 12v power splitter cables device-agnostic?

texts:
I am looking at purchasing this power splitter for the purposes of powering several identical 12V/0.5A devices:

Henxlco Supply Adapter

The goal is to avoid a mess of "wall warts" and the corresponding proliferation of power strips throughout my office.

My questions:

Can this product be used for other devices (not security cameras) with similar power requirements?
If I hook up 8 devices that each take 12 volts and 0.5 amps then is this power splitter a safe option?  There are other splitter cables on the market, but since this one is packaged with the power supply I am assuming it can handle a total of 4A draw (80% of the listed 5A).
Will the total power current draw at the wall (120V circuit) be the stated 0.8 amps?  Or will it be 1.6 amps, or 5 amps?

Thanks!


texts:
I am new to LTSpice and I was trying to make some experiments with BJTs. In particular i was trying to model a npn with VbeON = 2V. From the the ltspice site i found that the built in potential of the Base-emitter junction is given by the parameter Vje, but it doesnt seem to work.
Here the schematic of what I am working on:

But when i get to the simulation the operating point is still at more or less 0.6:

Is there a way to do what I mentioned? Where I am making mistakes?
Thanks in advance!


texts:
I have an 8BIT MAX160 Analog Digital converter I am using in several boards. I was wondering if there was a way to quickly test the accuracy of the ADC and output range of the ADC to verify bit errors, etc.

My idea was to increase the incoming analog signal one bit "count" in magnitude for each iteration in a loop:

ADC Input range 0 - 4.00 VDC

calculated mV/Count: 0.015625

Example:

Analog Input (VDC)      Expected Output

0.00            00000000
0.015625        00000001
0.03125         00000010
0.0625          00000100
0.125           00001000
0.25            00010000
0.50            00100000
1.00            01000000
2.00            10000000
4.00            11111111

Test method:

Start at 0VDC to see if any "stuck" bits/lines are present.

Do a "walking 1" for each successive magnitude bit position

Then do 4.0 Max input for All 1's

My question is, would this be a valid "quick" test to run an ADC through, instead of doing every possible input value from 0 to 255?


texts: I'm considering on creepage distances on my PCB. I have read UL840,there are two significant tables. 6.1 "Minimum acceptable creepage distances" and 6.2 "Minimum acceptable creepage distances on printed wiring boards". I have read post: Trace width and clearance calculations. I noticed that Dave Tweed recommends to use 6.2 table. But in table 6.1 there is a sentence: "Creepage distances for equipment subject to long-term stress". I'm considering what does it mean, and when i should use values from table 6.1?


texts: Current split between resistor and capacitor in parallel

texts:
I'm interested in knowing the formula which represents the voltage across the 10 ohm resistor.  I know that it's going to be the current multiplied by the resistance, which means I have to find the current passing through the 10 ohm resistor as a function of time.  I also know that when the capacitor is fully charged, the voltage across will stop changing (and as i = C dv/dt, the current will go to zero also).  This means that from this time on, it's just a series resistor circuit.

However, before this time, how would you find the voltage across the 10 ohm resistor?  Is the solution general for non constant input voltage?


texts: Inverting op amp design saturates at a fraction of power supply

texts:
I have built a simple inverting op amp. I am applying a 1 Vpp sinusoid at 10 Hz to a design with ~4.7x gain. The resistors I am using are 47kOhm and 10 kOhm. The op amp chip is the LT1222, and I am applying +/- 15 volts to power it. I also have 0.1uF capacitors running between the power supply and ground. The output sinusoid signal saturates around 4 Vpp, or at +/-2 Vp. From my understanding, the saturation voltage should be close to the supply voltage, and I'm not applying very much gain or a high frequency signal. What am I doing wrong?

Edit 10/3/19 12:43 PM:
Thank you for the replies so far. I have tried a few things including changing out the chip for a new one and a 741 and they both have about the same saturation voltage. I turned around the backwards capacitor and also added in a 10 uF in parallel to the others. I also replaced the short at the positive terminal with a resistor value of around 8 kOhms.

Here is a better drawing of my setup, a schematic and the actual output signal. The yellow is the amplified signal. There's some high frequency where the clipping is, but I noticed it goes away if I turn down the supply voltages to ~+/-6 V.


texts:
Can I swap the 820 µF 6.3 V capacitor on a Dell motherboard with any 820 µF 6.3 V bought from a local electronics store or are there other characteristics of the capacitor that I have to take into account?

The PC was bought in 2005, so I can't find the exact looking capacitor that's on the board. The capacitor is near the bottom of the board away from the RAM, so I am lead to believe that this would be dealing with the power supply.

One side of the capacitor says:

820 µF
kZG
6.3 V

And the other side says:

(M)105 °C
5(7)
3 V


texts:
I'm a bit confused on if I should be using integers in VHDL for synthesis signals and ports, etc.

I use std_logic at top level ports, but internally I was using ranged integers all over the place. However, I've stumbled across a few references to people saying you should only use signed/unsigned for synthesis-targeted code.

I've gone and reworked my current project to use unsigned... and, well, it's noticeably uglier.

Is it a bad practice to use integers? What's the problem? Is there some uncertainty on  what width the tool will map integers to?


texts: Charge Li-Po battery with TP4056? (Or what else?)

texts:
I bought a single cell Li-Po battery and two different charger modules (one without protective circuit and one with protective circuit) from AliExpress.

The Li-Po battery has a protection circuit board.

Both charger modules have the TP4056 chip. I found a datasheet for the TP4056 chip, in which the chip is described as "1A Standalone Linear Li-lon Battery Charger with Thermal Regulation in SOP-8". The datasheet only mentions Li-Ion batteries, but not Li-Po batteries.

The product description of the charger module without protective circuit says that the module is for Li-Po batteries: "This linear charger board allows you to charge lipo battery using either a Mini USB connector or a 4.5V - 5.5V input." However I'm not sure how accurate this description is.

The product description of the charger module with protective circuit says that the module is for 18650 batteries, which if I understand correctly are Li-Ion batteries: "5 V Micro USB 1A 18650 Lithium-Batterie Ladebordlader Module Neue Heiße Weltweit".

My questions are:

Can I safely use these charger modules with the TP4056 chip (or at least one of them) to charge the single cell Li-Po battery?
If both modules are ok, which one is preferable (Li-Po battery has it's own protection circuit board)?
If none of the modules are ok, which module can I use instead?


texts:
I am working on assignment in which I have a task  for selecting a sensor from various ,for that I am considering battery life as an criteria to decide, so calculating the time for which that sensor works on 2500mAh battery.
I have calculated in this way, taking reference from this post
For Ultrasonic sensor :

Opeartional current -- 0.015A
Standby current --14*10^-6
Operational duration --0.01 sec
Frequency -- 600 times/hr
On time = 6 sec
Off Time = 3594 sec

Life of battery = 0.015 * 6+ 3594 * 14*10^-6 = 0.09+0.050316 = 0.140 Amp
--> (2500mAh/0.140A) = 28 hr //Some thing wrong here dont know the what exact come here
Here Opeartional current and standby current are self explanatory.Operational duration is the time for which the senor on. Frequency is how many times a sensor go in to on state.
Average current = what I have done is -- operational current * Time for which it on + Standby current * Time for which it if off
Life = Total batter power/Avg Current
Is I am doing it correctly ? I am very confused with the sleep current, is it for an hr or for all time.
Please help.
Thanks in Advance.
EDIT1: Influenced by Polynomial comment, I have made all the units normalized basically time in seconds and current is in mA.
Second: Influenced by user25371 comment, Actually I missed to add, for the instance please ignore consumption by micro-controller.Regardless it is obvious it will connect using micro-controller.
Third : Please suggest Theoretical calculation, I am very aware that practically these things are going to very differ.


texts:
I am currently using ADuM4160 by Analog Devices as a USB isolator.

However, this part is EXPENSIVE. I was wondering if anyone thinks it can be replaced with ADuM2200.

Any reason why this wouldn't work? If so, any thing that needs to be done to make it work?


texts: Most manufacturers produces crimped and straight lead pairs of their capacitors which has exactly same capacitance and voltage rating. Why do they bother crimping the leads? What advantage does it make? In which cases a crimped lead capacitor should be preferred?


texts: STM8 nested interrupt bug, not described in current errata sheet ES019

texts:
If main process execute WFI with AL bit set in CFG_GCR, changing I1/I0 priority bits in the ISR cause CPU stalled when nested IRQ occured.

Preconditions: all ITC_SPR1 registers has default value 0xFF.

Enable TIM4 with generate interrupts on overflow. ISR for TIM4 contain only code for clear TIM_SR1_UIF bit in the TIM4_SR1 register.
Unlock EEPROM for write, initiate byte write procedure and enable IRQ for EEPROM write operation complete. In the ISR for EEPROM raise IRQ level by RIM instruction or direct specify I1/I0 bits by PUSH #8,POP CC (for example).
Main programm set AL bit into GCR register and execute WFI instruction.

If in the EEPROM ISR IRQ level raised by RIM or PUSH/POP CC instructions and then occured IRQ from TIM4, then after IRET from TIM4 ISR core is stalled and EEPROM's ISR is not continued.

Workaround 1.
Clear AL bit into GCR before execute WFI instruction in main loop.

Workaround 2.
Clear AL bit into GCR in EEPROM ISR before execute RIM or PUSH/POP CC instructions

Workaround 3.
Set IRQ level for EEPROM other than I1=1, I0=1 (for example ITC->ISPR1 = 0b11110111; before initiate EEPROM write operation).

I don't found this bug in current errata sheet ES019.

I see this bug on STM8L-Discovery board with chip stm8l152c6t6. Can someone reproduce this bug on same or different chips? Please confirm or decline it.

Example:

tim4ISR() {
    /* clear UIF */
    TIM4->SR1 &= (uint8_t)(~TIM_SR1_UIF);
}

eepromISR() {
    (void)FLASH->IAPSR; /* or other manner read IAPSR */

    /* Set some pin to indicate in-ISR state */

    __ASM("rim"); /* or __ASM("push #8\npop cc\n"); */

    /* delay into ISR */
    for(int i = 0;i < delayN;i++) ;

    /* clear AL for leave WFI after IRET and initiate next byte write */
    CFG->GCR &= ~CFG_GCR_AL;

    /* Clear some pin to indicate leave ISR */
}

main() {
    /* Set TIM4 for generate periodic IRQ */

    /* Unlock MASS */

    while(1) {
        /* Initiate EEPROM byte or word write operation */

        /* IRET stay on wait mode */
        CFG->GCR |= CFG_GCR_AL;

       __ASM("wfi");
    }
}


texts: Stellate EEG Machine, would like to read the input in real-time, need to jury-rig it

texts:
I don't have an electrical engineering background but a neuroscience one, so apologies in advance for my poor knowledge.

Basically I have an EEG machine (Stellate Harmonie) and I would like to be able to read the data in real time. Unfortunately it saves the EEG output as a .sig file and the app itself is clunky and does not conduce itself to doing so. I am working with software engineers that code in python that are ready to work on it but can't until we can figure out a way to read the output of the machine in real-time. Any method to be able to figure this out would be greatly appreciated!

Edit: looking for a manual, but found this meanwhile, the image of the setup is here: http://userfile.alephnetwork.com/files/b2gmarekt_vendor/Stellate%20Harmonie%20%20E%20.pdf


texts:
I am new to LCDs and I am trying to interface my LCD (used in Nokia 3310 cell phone) with PC via Parallel port. I searched on Google and I found many programs and schematics which can used to draw image on it. But I want to understand the actual functions of the pins of LCD named as VCC, RES, etc, so that I can develop my own program on C#.Net.

The Pin arrangements are as follows:


texts: How to by-pass non-functioning 4-post volume pot

texts:
I have an old AT&T Tel. answering device that I would like to keep going as long as possible. However, the volume pot is absolutely shot after trying to service/clean many times. I haven't been able to find a replacement pot so I would be delighted to just have the volume "loud" if possible leaving the bad pot in place. Is there a way to by-pass it? Perhaps with a jumper? If so, how should it be done? I have included 2 photos of the double-sided circuit board with descriptive comments for reference. The third photo is of the actual speaker.

Photo 1 - Top-side of board showing pot (black rectangle)

Photo 2 - Underside of board with outline of pot position

Note that the posts are numbered 1,2,3,4 consistently on each side.


texts: Inductance calc for Edge Coupled Differential Pair?

texts:
Apologies up front if this topic has been addressed. I've searched on StackExchange and am concluding that this structure is uncommon as there is no ground return accompanying the differential pair shown below.
I'm hoping to find an inductance calc for Cu on a substrate (substrate thickness approx 25 um):

++++++++++++++++++     -------------------
       <- 25 um thick substrate ->

* +/- is to show this is a diff pair with length running in/out of screen
* thickness of each strip is <= 1 um
* separation between the strips is >> thickness
* width of each strip is > separation

Even a crude calculation would help.

Thanks!


texts: What is the Ah to voltage relationship of a 12 V lead acid battery?

texts:
I've a DC motor (brushed) that is driven by a set of 12 Ah 12 V lead-acid batteries. When motor stops moving, I assume that all the current (at least most of it) in the batteries is drained. However, when I check the voltages of each battery they are well above 12 V. The motor has no load current consumption of 2.2 A and peak current consumption ~15 A. So, I would like to know at what voltage all the 12 A of the battery are discharged? Why would motor completely stop moving (i.e. with no load) when there is full battery voltage left? (Is there something wrong with the motor or I am missing something? - BTW motor heats up quite a lot)

*** Motor has fused by now so, this probably is not entirely relevant practically. The problem was that brush board of the motor was loose and got in contact with the coil resulting in shortage. However, this is theoretically still a valid question.


texts: Does load resistor value in constant current setup affect power delivered from source/battery?

texts:
I am bulding a battery pack of 48v using 18650 cells salvaged from laptop batteries. I have to test them for their capacity to use in my project of converting bycycle to electric. So i have couple of imax B6 charger/discharger and a HTC 240Duo charger/discharger. which can do only 1 or 2 cells discharge at a time. so for large quantity of testing i designed a circuit using Arduino mega 2560 mini version and LM324 as comparator. I have attached circuit diagram along with this and also the pcb i t.hat is designed. i have used the code from brettwatty's
arduino-mega-8x-charger-discharger-offline
Circuit diagram
PCB
In this i am calculating the mAh with constant current for e.g., 500mA or 0.5A and if the discharge process continues for 4 hrs. then, the capacity would be
(0.5)(43600)*(1/3600) = 2000mAH.
Here i am not considering the load. If we discharge the battery with different Load resistance and keeping the same current value as 0.5A does the calculation to find capacity has aslo to be changed?

I am reading voltages in two points A and B  as battery and load voltages respectively(shown in circuit diagram fig 1&2). And using load resistance value, calculating the current drawn. If the current drawn deviates, then will adjust the PWM signal such that the current remains same even if the battery voltage decreases.
If the same is calculated using resistance with four hours of discharge, then
fig-1, value R = 2ohms,I =0.5A, power I2R = 0.25*2 = 0.5W, for 4H = 2WH -> 2/3.7 = 540mAh
fig-2, value R = 5ohms,I =0.5A, power I2R = 0.25*5 = 1.25W,for 4H = 5WH -> 5/3.7 = 1351mAH
calculated without resistance value included (0.5)*(4*3600)*(1/3600) = 2000mAH.

Sometimes when you keep on thinking too much and miss something completely silly thing. So i am asking all of you anyone who is able to tell me the mistakes i am doing and also to demistify the capacity calculation.
Currently I have just finished coding and now i am tesing the accuracy of the system i have built. And came up with this doubt. Which method to use for calculating the capacity of battery, for my setup above. Or any method which i can improve calculating the capacity.
If this is not the place for this kind of question then please let me know which will be the suitable platform for this type of question.
Thank you.


texts:
Yesterday I debugged a program on my STM32F103C8T6 with Eclipse STM32 workbench without any problem.

Today I tried the same but constantly get this error.

What I tried to fix:

Erase the chip with ST-Link Utility successfully
Restarted the STM32 workbench
Removed power
Replugged (in different USB port) the ST-Link

Nothing of these actions helped.

What can I do to be able to debug again?


texts: Design a Decoder using Logic Gates to display letters on a 7-Segment Display

texts:
The task I got is to design a similar circuit to a standard BCD to 7-Segment decoder, except only using Logic Gates and to display a eight letter character word, for example: SHELFLES

As I have forgotten all by now as it comes to digital logic, k' maps and etc.

I would appreciate points and tips for a direction to how I should go about doing this.

Thanks in advance!


texts:
Possible Duplicate:
  2 Phase to 3 Phase conversion

Is there a way to run a 3ph induction motor with one phase .

Basically I have 3ph motor but my power supply is only 2 phase . Is there anyway I can run it ?

Motor spec :

3ph
induction motor
Hi-tone
ref to is 325
FRAME 80  Duty S1  Hz 50    Insucl.cl.e
V 400/440   RPM 1440  AMP 1.9
K.W. 0.75   H.P 1  M.No : 11209


texts: In an RGB scene, why can we assume color difference images are band-limited?

texts:
A common assumption in image processing is that the difference between two color channels of the same scene are band-limited.

For instance, the interpolation method used in Hirakawa's paper introducing Adaptive Homogeneity-directed Demosaicing fundamentally uses the assumption that (G-R) and (G-B) images of the same scene will be bandlimited relative to R, G and B images.

This assumption is also used to motivate decomposing video signals into Luminance/Chrominance components to save on data rate.

I feel like I am missing something very simple here. What justifies this assumption, and can it also be made for (R-B)?


texts: Arduino, controlling leds with 3.3V even though dig. has 5V?

texts:
The LEDs I have can nicely run on 3.3V, with a minimal power dissipation to bring down 3.3V to 2.0V.

My Arduino has 5V for its digital pins however, and I do not know of a way to use 3.3V unless I use the 3.3V pin and not the digital pins.

To avoid unnessesary power/heat (even if not too much) is it possible to control my LEDs through a lower voltage than what the digital pins provide?

My first thought would be the analogue pins, of which range from 0..255,

5V / 1.5V (analogWrite(pin, 192)) = 3.33V, would this be a good replacement?

Any other suggestions on driving many, but low voltage LEDs?


texts: Boost converter with input-referenced output

texts:
I'm building my first switching DC/DC converter as part of a larger circuit. I need to convert a input voltage range to an overlapping output voltage (e.g. 3-5V in, 4V out). This would typically be done with a buck-boost or SEPIC converter. I thought of a way to use a simple boost converter IC instead. If it works, it allows me to go monolithic, while an equivalent buck-boost would require a controller + MOSFETs considering the ICs that manufacturers offer (high currents involved).

Because I don't need the output to be referenced to ground, I was planning to reference the load to the input voltage and change the switching IC feedback network to subtract the input voltage from the output.

For example, let's take a 4V output. Load is connected between input and output.

Input = 3V, the converter generates 7V (from ground), potential across load is 4V.
Input = 5V, the converter generates 9V (from ground), potential across load is 4V.

It seems to me like it should work and that I can calculate the inductor/switch current based on the actual voltage across the load. I searched a lot, but couldn't come up with much. The best I could find is the "Negative-to-Positive Buck-Boost Converter" circuit from page 24 of LT's AN19, which looks very similiar to what I'm talking about (with input voltage as ground and ground as negative voltage).

Can this be done? If yes, can inductor and switch currents be calculated on the voltage across the load instead of the full ground-referenced one? Seems logical since the inductor is in series with the load, but if it's not true then I don't get any benefit out of this and I'll have to go with a controller.


texts: 555 timer: how to set values to take an hour

texts:
I'm new (and novice) in electronics. I came to seek your knowledge to see if someone can help me with a very basic circuit.

It is a 555 chip, which should light a LED (for about 1/2 second) every hour. I managed to make the circuit diagram with a well known software.

My question is that I do not know what values to put the resistors and / or capacitors to achieve this frequency of light or flash. Actually, this triggers a parallel circuit (so I need the trigger every 1 hour). I guess there must be some calculations to obtain these values, but what I've seen online I find very difficult to understand. I am not a student of electronics, only an amateur trying to learn as well as realize a project. Now the circuit works, but not in the desired frequency flash lighting (every hour a little flash).

PS: Attached image of the schematic. Sorry for possible faults in the text, I used Google translator.

PS: I think this is an astable and oscillator circuit... but I'm not sure.


texts: What kind of PLL is used to recover the clock from E.G. USB 2.0 data stream

texts:
I would like to create a communication protocol to connect two FPGAs. I would like it to be fairly fast, (a couple of 100s of Mbps) but only use a single differential pair.
This kind of thing is possible. USB 2.0 uses a single differential pair, and the receiver can reconstruct the clock because the data has been 8b/10b encoded with enough edges to synchronise the clock.
With a fast enough FPGA (or slow enough data stream) this can be done digitally by oversampling. Indeed I have implemented this myself and had it working. However, If I want to push the clock rate up higher, at some point there will need to be some kind of hardware clock recovery circuit.
I am trying to select an FPGA which can do this, but my problem is that I don't know the name of this kind of clock recovery function. Most FPGAs have PLL blocks, but I'm assuming that they aren't suitable for this.
Question: When I am looking at the datasheet for an FPGA, what are the keywords I should be looking for that mean this FPGA is capable of recovering the clock from a high speed data stream on a single differential pair? What is this kind of clock recovery called?


texts: Parallel connecting USB power for higher currents

texts:
I am trying to find any way in which I can have a higher power output from a USB power bank, by combining multiple USB ports in parallel. The USB power bank has 3 outputs, one rated at 2.1A and the other two rated at 1A. How do I do this exactly?

One idea would be to use a splitter cable and then combining multiple ports to one, but how would the power be distributed across the wires? I don't think a thin USB power wire is able to handle > 4 amps. Any solution to resolve this issue?


texts: Designing/looking for a circuit board for a vaporizer

texts:
I recently decided to look for/create a board for a vaporizer and have no idea where to start. I will probably end up programming the program in C or C++. To better explain this, I will explain the function and components I need. I will use two 3.7v 18650 batteries. The batteries power the board. The board ideally needs to output 10 amps using 5 volts. The board need the capability to check the resistance of a coil in which the batteries heat up. There are 3 buttons. 1st button to heat the coil up and the other 2 to switch between wattage. Changing the wattage changes the voltage and amp output. The program has to do the following.

I need to measure the resistance. (Ohms) To do that I first need to know the voltage the battery is generating. The starting voltage and wattage will be preset. (The watts need to be preset anyways since it's needs to be displayed.) Then, using the ohm's law algorithm I can calculate that by using,
Amps = Watts / Voltage
Ohms = Voltage / Amps
The watts are displayed and are controlled by the user. By changing the watts it then changes the voltage and amps.
Amps = sqrt(Watts / Ohms)
Voltage = Amps * Ohms

Question:
Is my logic flawed in anyway?
Does anybody know of a board that can do this?
If I have to build my own board, what are the components I need?


texts:
A quick answer required !

#define PortA_Data (*(volatile unsigned long*)0x40004000)

here in this example I linked PortA_Data with an address, can any body explain the mechanism of this code, there is pointer to address, there is a pointer to return type, is there any function here? I can't understand what it mean.
I know about pointers but there is something messy, really annoying me.


texts: Logic Gates - Did I connect them correctly?

texts:
I have 2 logic gates problems I need to solve applying de morgan's laws and I just wanted to make sure whether I did it correctly or not.

I am supposed to create the function F=abc+d using only the NOR gates.

What I did was this:

Create function F=anegb+abc+negbc only using NANDs.

And for this one I tried this but I am not so sure about this one:

I'd be glad if any logic gate pro could take a quick look at it and let me know what you think.
Are they okay or am I not even close?
Thanks a lot!


texts:
I have several 3-axis magnetometers mounted on breadboards, and they all read correctly in the x and z directions.

The Y direction is very strange; when turned to read 0, then turned 90 degrees counter clockwise, it reads 0 again. Then the values gradually get larger, peaking at about SE.

What could cause this behaviour?

I thought I had determined the breadboard itself was magnetic but I can't reproduce that.


texts:
I have 2 checks which are similar, except by the range of the generate:
All works OK, it looks like this:

check : for bit in (1 to 5)  generate
  process
          some cool stuff;
  end process;
end generate  check ;

check2 : for bit in (7 to 8)  generate
  process
          Same some cool stuff;
  end process;
end generate  check2 ;

I would like to implement something simpler to maintain like this:

check : for bit in (1 to 5) & (7 to 8)  generate
  process
          Simpler to mantain the cool stuff;
  end process;
end generate  check ;

Is this possible ??


texts:
I am trying to implement a PID controller in the z-domain.  What I have done so far is found some values of \$K_p\$, \$K_i\$, and \$K_d\$ that work in the time domain.  I have found some information on how to translate these values into the z-domain, but when I run the new simulation with the digital PID controller, it no longer seems to work.

For your reference, the \$K_p\$, \$K_i\$, and \$K_d\$ values I have are 0.25, 0.6, 0.005, and when i converted these to the canonical form (in z domain) I had \$a_0 = 500.25\$, \$a_1 = -1000.25\$ and \$a_2 = 500\$. (used \$T = 10^{-6}\$.  When i plot these two things (using a sinusoidal input), the outputs are different and I can't quite figure out where I am going wrong with this.

EDIT: I guess as a more direct question, how can i take time domain parameters\$K_p\$, \$K_i\$, and \$K_d\$ and turn that into a digital/ z domain difference equation for a microcontroller?
TIA


texts:
I'm relatively new to electronics and have never used a DAC before. I have a DAC0800 and a LF351N op-amp and have tried to set them up so that I can have a voltage output determined by the 8 digital inputs to the DAC.
My plan is to eventually connect the DAC inputs to the outputs of an EEPROM chip. The analog output of the DAC will then connect to the control pin of a 555 timer, to change its frequency.
To power it, I am using four 1.5V AA batteries in series to give 6V.
I was wondering whether anyone has any experience with this chip or circuit diagrams that could help me figure it out? It's the power that's the issue - the examples I can find usually use a dual rail supply of more than 6V, but I'd like to avoid that if possible. Alternatively, is there an easier way of producing a square wave of digitally-controlled frequency, than using a DAC connected to a 555 timer?
Thank you!


texts: What happens if the load (connected to the output of the circuit) disconnects suddenly from Arduino/ESP32?

texts: My circuit (that contains esp32 with few current and voltage sensor) is connected to 9Ah Battery (with BMS), where the load gets connected to see the discharge rate of the battery. There are times where I need to disconnect the load in the middle of discharge. What will happen if I continue to disconnect the load from the complete circuit again and again? What should be added in the circuit to avoid any sort of issue?


texts: ATSamd10 Atmel ARM programming via UART bootloader

texts:
I'm trying to collect info on how to program ATSAMD10 chip (Atmel Cortex-M0 ARM).

E.g. with LPC111x from NXP I've used gnueabi gcc toolchain to create hex-files and then uploaded them via UART using LPC21PRG or MXLI tool. It only required to drive low PIN0_0 during reset to enter bootloader programming mode.

As far as I can understand, for Atmel chips I need to use SAM-BA utility. However I could not at once find which pins help to enter bootloader mode, what minimal hardware configuration is needed etc. However as about firmware, I think the same gnueabi gcc and hex files should be ok, right?


texts: How to specify the start up condition in an oscillator simulation using Cadence Virtuoso?

texts: A real oscillator starts oscillating when there is some noise injected into its input. However, in Cadence virtuoso, how can I inject some noise into the input of the oscillator and make it oscillate?


texts:
I am on a very exciting project, by the SIM800L module is resisting hard !

The hardware :

clone arduino nano (dx.com)
SIM800L module + antenna (dx.com)
Lipo battery 3.7V 150mAh (letmeknow.com)

The problem :

the SIM800L module does not respond to AT commands.

In detail, sometimes the serial is available, put print nothing on the Serial monitor.

The code :

#include <SoftwareSerial.h>

String Arsp, Grsp;
SoftwareSerial gsm(11, 12); //  RX, TX

void setup() {

  Serial.begin(9600);
  Serial.println("Setup");
  Serial.println("Testing GSM SIM800L");

  pinMode(LED_BUILTIN, OUTPUT);

  gsm.begin(9600);
}

void loop() {
  // turn on the led
  digitalWrite(LED_BUILTIN, HIGH);

  if(gsm.available())
  {
    Serial.println("gsm available");
    Grsp = gsm.readString();
    Serial.println(Grsp);
    Serial.println("gsm available end");
  }

  if(Serial.available())
  {
    Arsp = Serial.readString();

    Serial.println("Serial available");
    Serial.println(Arsp);
    gsm.println(Arsp);
    Serial.println("Serial available end");
  }

  // turn off the led
  digitalWrite(LED_BUILTIN, LOW);

  delay(500);
}

My trials & errors so far :

I took care of correctly powering the SIM800L with proper voltage.
all ground are common (battery and arduino).
rx to tx and tx to rx checked 100 times.
changing pin numbers also.
the sim inserted is connected to network sometimes, but not always. When connected, I can call the number and I hear the correct "ring" tone in the line.
the led of the sim800L module is blinking slowly when connected. But 50% of the time it's also blinking 1 Hz like it's looking for network.
the RST pin of the sim800L module is connected to the 3.3V port of the arduino.
I have changed the baud rate of the softwareserial object to 1200 2400 4800 and 9600 without success.
I have checked "Both NL & CR" in the serial monitor settings.
I have post "AT" and "at" and all other things.
whatever the command, the module never answer a clear string. It's either empty, or "?" signs.
and finally, without touching it, the module is "available" from time to time and output nothing.

Here is a log as an example after a reset:

I am lost ! All help will be greatly appreciated, thanks a lot.


texts:
This configuration of OPA134 in LTspice has have a gain of 1.5 and hence should have a voltage output of 3. However it does not. Why?

Spec: http://www.ti.com/lit/gpn/opa4134
Spice model: http://www.ti.com/lit/gpn/opa4134
in design and development tab

I may be missing something in the spec, however any other op amp I use produces an output of 3V, so it seems weird for this one to produce an extra amount of voltage. If it is an integer gain, then the output voltage is as expected, however any float gain then it produces a bit more voltage than necessary.


texts: Softcore vs hardcore for power consumption

texts: What is the difference between soft core and hard macro processors used in FPGAs in terms of power?


texts: DALI: How do I delete the short address from a device?

texts:
I have a device that already has a short address. I need to delete this short address so that I can do the initialisation process again (from random address to short address).

Can this be done? What commands do I have to send?