texts: MCU analog reference voltage and Voh question

texts:
If I feed 2.5v to Vref pin on a MCU runs on 3.3v, what is the voltage for Voh?

I though Voh would be around 2.5v but I found the following table for the MCU(http://www.st.com/content/ccc/resource/technical/document/datasheet/03/b4/b2/36/4c/72/49/29/DM00071990.pdf/files/DM00071990.pdf/jcr:content/translations/en.DM00071990.pdf)

looks like Voh has nothing to do with Vref, so I am confused.


texts: Current going into the positive pole of a battery while discharging a capacitor

texts:
Please bear with me if this is a fundamental question.

Let's suppose we have an RC circuit, charging a capacitor up to the voltage of a battery of 9V. The capacitor is currently at 9V, we switch the 9V battery with a 3.3V one.

Because of the difference in potential of 5.7V between the capacitor and the battery, does current now flow into the battery?

What are the dangers when this happens? Am I trying to charge it at this point?


texts: What does this wiring schematic symbol mean?

texts:
I ran into this wiring symbol today and haven't been able to find out what it means. Somehow internet search of "criss-cross wire schematic symbol" wasn't especially fruitful.

Is this something I need to worry about or is this just a representation of a USB connection?


texts: How can I connect this LCD panel to my Raspberry Pi?

texts: I want connect my Raspberry Pi to this  LCD. How I can do this? I have read about lvds controller. Is this the solution to my problem? Could someone help me in my research? I'm Italian and I'm searching on amazon.it LVDS controller. Sorry for my bad English.


texts:
I purchased a RC car and tore out the electronics and replaced with an Arduino. I am powering the DC motor from the battery but when it loses capacity it loses power. So the current is varying.

For example: when I run the motor at 50 and its charged it goes fast but even ten minutes later it's significantly slower for the same code.

7.2v Ni-MH 6cell
Arduino uno
Vnh5019 motor shield:  Battery plugged directly into there and also powers the uno since they stack.

I was wondering if I should use a linear regulator or buck converter to have a constant voltage or if there's a better solution.  I am new to electronics.

Thanks!


texts:
Supose I have an opamp with pnp input stage (constant current flowing out the input pin), like the following:

simulate this circuit – Schematic created using CircuitLab

Would the input from OA2 be susceptible to noise since the current flowing through it is low?

Could I 'fix' this problem by inserting a pulldown very close to OA2 and let OA1 source this current?


texts:
This is the continuity of this: Understanding Electric Shock Box Circuit

I really don't understand what is going on, so I was hoping that simulating the circuit in Proteus might help

What parameters should I pick for the transformer?

For example, in Primary Magnetic Inductance do I need to add the inductance of the Primary Extremes, without counting the center-tap, right? I don't know what to select in Turns Ratio (Np/Ns), neither in leakage inductance, neither in trace inductance, neither in Losses .. Could you help me?

These are the values that I have gathered about the transformer:

Primary

Red_1-Red_2 = 760 mH / 6.8 Ohms
Red_1-White = 150 mH / 3.8 Ohms
Red_2-White = 148 mH / 3.2 Ohms

Secondary

Black_1-Black_2 = 33.5 H / 514.6 Ohms

Unfortunately, when I try to run the simulation with the parameters previous displayed, Proteus shows an error:

I was also thinking, what would be the equivalent circuit of a human body? Currently in the simulation I am using a 250 Ohm resistor, but as I long as I understand the human body also behaves as a capacitor

and I have seen models that add an inductance component too .. So, does any one know what would be an equivalent circuit? What values of resistance and capacitance should I pick?


texts: SPI Transfer with STM32F4 board gets stuck on SPI_WaitTX

texts:
I am new to the whole embedded hardware thing, and I am getting stuck when trying to connect my STM32F4 Discovery board to a Bosch BMX_055 IMU unit.

Here is a snippet of the code I am trying to run:

bool testConnection() {
    SPI_ResetCS(&IMUSpi);
    SPI_Transfer8(&IMUSpi, 0x0);
    int chipId = SPI_Transfer8(&IMUSpi, 0x0);
    printf("Chip Id: %d\n", chipId);
    SPI_SetCS(&IMUSpi);
    return true;
}

My code then gets hung up in here:

inline uint8_t SPI_Transfer8(Spi* spi, uint8_t value) {
    *(uint8_t *)(&spi->spiPeriph->DR) = value;
    SPI_WaitTX(spi->spiPeriph);
    SPI_WaitRX(spi->spiPeriph);
    //SPI_WaitBSY(spi->spiPeriph);
    return *(uint8_t *)(&spi->spiPeriph->DR);
}

on the SPI_WaitTX function.

Any ideas on why it is stuck/how to fix it would be greatly appreciated!


texts:
I have a Linksys WMP54G v 4.1 Wireless PCI card from an old computer I would like to use it for something but I have a problem.

The end that the antenna attaches to is broken (See picture). I was wondering if I could somehow attach a new end to it? I have a connector I think is called an N connector, I know it better as RP-TNC. The card had an RP-SMA connnector. Is it possible to solder the connector to the broken one? (See Pictures).

Picture1
Picture2
Picture3
Picture4


texts: Can decoupling capacitors affect an Arduino?

texts:
I designed a PCB that has a 74HC14 to catch pulses and powered the PCB from the Arduino's pins (3.3V and gnd.) I placed a 0.1uf ceramic capacitor  between Vcc and gnd pin of the IC. I also added a 10uf capacitor directly on Vcc (3.3V) and gnd of the Arduino.
Is placement of 10uf wrong? The Arduino stops working after a few days. Does it affect the microprocessor? Where should the 10uf capacitor to be positioned, how many cm away from IC?


texts:
I'm working on a Nixie clock based on a STM microcontroller. It consists of two boards: one includes the microcontroller and a boost converter and the other includes the tubes and two HV5530 high voltage shift registers.

I noticed that the clock works fine when one tube is on, but when I try to turn more tubes on, it behaves strangely and some tubes turn off. The code was trying to display '123456' and to update the registers every 100 ms.  Here is a video of this problem.

https://www.youtube.com/watch?v=nN-ojr2xXTM

After some hours of investigation I found the cause: ringing in the boost converter which adds noise on the ground and on the traces that go from the microcontroller to the HV5530 chips. Here's a scope capture of that. Channel 1 is the switch node of the boost converter and Channel 2 is the clock signal probed right at the input of one of the HV5530 chips.

Here is the schematic:

And here is the layout:

I added a snubber between the switching node and ground consisting of a 100 nF capacitor and a 1.2 K resistor. The improvement is only marginal and the resistor gets really hot.

And finally, my questions are:

Is there an obvious schematic or layout error that could cause the ringing?
Is it wrong to have a ground plane under the boost converter? I'm thinking about the fact that it adds stray capacitance to the traces.
How should I calculate the RC snubber?


texts:
Let me start by saying that I'm a student, so I apologize if this is a stupid question.

I have a "power supply" that initially supplies 2 mA of current for a few seconds and then drops down to 100 uA over 30 seconds. I'm trying to find a way to limit the output current from this supply to 100 uA or less, i.e. prevent it from exceeding 100 uA, but every IC that I've checked doesn't allow for this either at the lower limit of quiescent current or the upper limit of quiescent current.

An LDO like the LM317A seems to fit the bill, but I'm worried that this is overkill since the input current is so low and it kills the efficiency when compared to a switching regulator.

I briefly considered using a digital potentiometer controlled via microcontroller, but that's possibly the most complicated way imaginable to tackle this.

Is there a simpler way to limit the current to 100 uA that I'm unaware of? All of the ICs that I've looked at seem like overkill.

EDITED: This power supply is from a small photovoltaic cell. I would prefer to keep the voltage as low as possible, which is around 0.5 volts from the PVC since it's so much easier to add resistance than take it away, but I'm open to any ideas. Think Ti-30 calculators that use a small cell.


texts: Does the output bypass capacitor of an LM7805 double as a decoupling capacitor?

texts:
I'm using a 5v linear regulator (specifically an LM7805) that outputs directly to an ATMEGA328P. According to the LM7805 datasheet (page 23) input and output bypass capacitors should be used, as seen below, to tame peaks and ensure stability.

It is good practice to also include a decoupling capacitor in front of an IC, in this case an ATMEGA328. Does the 0.1μF capacitor on the output side of the LM7805 act as a decoupling capacitor if the regulator feeds into the IC directly after the output bypass capacitor?


texts: Op-amp envelope detector - capacitance load issue

texts:
I have setup the below circuit; a basic envelope detector, however I believe that the op-amp is struggling with the load capacitance.

With the 100nF cap removed, then the output of the op-amp behaves as expected following the input voltage (AC around 1.6v DC). The output of the op-amp is driven higher to make up for the diode voltage drop. (Below scope trace, blue input, red output).

However when the 100nF is added, then the op-amp is not drving the output high enough. It just stays around 1.6V. In theory the output voltage should rise to around 1.9V.

I added the 2.2K output series resistor to try and get round the issue, but it didn't help. Are there any obvious errors or ways around the issue?

It may be that I need to use a different op-amp.

Thanks


texts: Deviation between datasheet ESL and actual measurements

texts:
Optimizing a PDN, I am trying to arrive at a result that is as accurate as possible. Murata specifies the following ESL for a generic 0805 MLCC (Figure), but comparing this to the measurements presented in the AVX paper below shows orders of magnitude in difference, i.e. 10pH vs 1nH.

Any advice on how to arrive at an estimate which is as accurate as possible? I suppose I should also take into consideration the total loop inductance, particularly on bulks located further away from the IC.

Thanks!

AVX Induction paper

Loop Inductance


texts: How to separate ground efficiently in a thyristor circuit controlled by sensitive microcontroller

texts:
I've been trying to design capacitive discharge ignition circuits using a microcontroller ARM (Texas and ST) without success.  Each circuit using them presents intereference problems during spark generation that I can´t solve...

I believe that my main problem is a GND plane and layout, but I don´t know how to separate efficiently the power ground  and logic ground when I use a thyristor (because  the terminal K is common in power circuit (A-K) and control (G-K).

All examples that I found and I used as reference are based in PIC or AVR feed 5V.  I basically copied the circuit by changing only the microcontroller.  Is the STM32F103 sensitive to use in this kind of circuit? Is it possible to live with this noise coupled (when spark is generate) without loss in my circuit?

Because for more than I tried, I can´t eliminate this noise in GND and I believe it is responsible for crashing the uC...

My last PCB layout (used in my tests):

To increase information about my instalation:

My analysis (maybe I made have be wrong in green point):

This part is the CDI circuit (In my test I used a external Charging Coil - AC CDI):

Power supply and power latch(to save important data before microcontroller power off):

Microcontroller connections:

Inputs and Outputs (connector) used in my system:


texts: Exascale Supercomputers Power Consumption

texts:
I don't know if its the right place to ask. I have read a lot of articles about exascale and found out that it may consumes approximately 20MW power envelope. Is it a daily basis or a yearly basis or in an instant?
Please enlighten me. Here are the papers I have used.

http://www.cs.utexas.edu/~skeckler/pubs/SC_2014_Exascale.pdf

page 1:

  One of the main challenges in achieving this goal is power consumption, which a range of HPC system operators have suggested be limited to 20 MW for a full exascale-capable system to mitigate cost of ownership and new power delivery infrastructure costs [2]

and

http://www.computermachines.org/joe/publications/pdfs/hpca2017_exascale_apu.pdf

page 1

  An exascale supercomputer is envisioned to comprise of on the order of 100,000 interconnected servers or nodes in a target power envelope of ∼20MW, with sufﬁcient memory bandwidth to feed the massive compute throughput, sufﬁcient memory capacity to execute meaningful problem sizes, and with user intervention due to hardware or system faults limited to the order of a week or more on average [3]


texts:
I am trying to test a AD8307. Here are my connections:

(pins not shown are left unconnected, and also pin 8).
I get a quiescent output voltage at pin 4 of about 850 mV with respect to ground, which, to my best understanding, means that the IC is fake.
What do you think?
Note: According to the datasheet, the input impedance of the IC is 1 kOhm. I am not working inside a microwave oven or near high voltage sparks, so, I can hardly imagine that the tiny pin 8 acts as an antenna or so to provide such a voltage discrepancy, but to make that sure, I tried to put it in a metal box and that made no difference.


texts: How to get values of voltage and current at different times ,using pspice?

texts: This is probably a really trivial question nevertheless it has had me confused for a while. I'm trying to solve a circuit using PSpice and for that matter I need to get the values of different node voltages and a couple of currents at different times. How can I do it? Please be as thorough as possible because I'm a newbie.


texts: Difference between O-QPSK with half-sine shaping and MSK?

texts:
The IEEE 802.15.4 standard specifies that O-QPSK modulation with half-sine pulse shape (HSS) should be used at the 2.4 GHz band. But according to Wikipedia, O-QPSK modulation uses square pulses, and O-QPSK that encodes each bit as a half sine is just Minimum Shift Keying (MSK). So these seem to be two names for the same thing.
What confuses me is that elsewhere in the literature O-QPSK with HSS is treated as different from MSK. For instance, it is often said that a IEEE 802.15.4 frame can be demodulated either using O-QPSK or MSK. Apparently using O-QPSK allows to achieve higher sensitivity than MSK, but is more complex to implement.
My initial thought that the difference between O-QPSK and MSK is coherent vs. non-coherent receivers, however, both O-QPSK and MSK receivers can be coherent or non-coherent. This article suggests that the difference is that O-QPSK uses zero IF, while MSK uses non-zero IF. I cannot wrap my head around this - where does the non-zero IF come from, and how is it used in the demodulation process?
Can someone explain how is the demodulation process differs between MSK and O-QPSK with HSS?


texts: Is this the correct fuse to use on the primary side of a transformer?

texts:
I am trying to design a linear power supply to learn how AC is stepped down and converted into DC. However, I am having trouble figuring out how to choose a fuse value for use on the primary side of the transformer. I have done some research and learned that for inductance loads, such as transformers and motors, you need a slow blow fuse because of onrush current. However, I have read in some places that the fuse should be valued at the amperage of the primary side. In other places I have read that the fuse should be valued 1.5x or 2x the primary side? Which is it?

For my particular instance, I am using a step down transformer which takes 115V on the primary side and provides 12.6VCT at a maximum of 2A on the secondary side. (I will be using this on US mains, which I assumed would be okay, so I expect the secondary voltage to be a tad bit higher.) This gives me 25.2 VA, which means that the primary side should draw about 25.2VA / 115V = 219 mA of current, plus some for inefficiency.

Because I am planning on drawing only 1.5A out of this supply in order to preserve my voltage regulators, I thought that a 200mA slow blow fuse should be adequate for my use. I also plan on placing a 2A fast blow fuse on the secondary side as well. Do these values seem correct?


texts:
I want to use an Inverted F-Antenna for my next project, but I'm struggling to find some good design information.

I have read that the length of the arm "L" is roughly a quarter wavelength of the desired resonant frequency.

I also read that the antenna impedance is actually determined by the shorted stub left of the feed and the open stub right of the arm.
So by moving the feed point "L1" the impedance can be tuned to 50ohm.
This have I seen done in practice by trimming the length "L" of the antenna, but this would change the resonant frequency and the impedance simultaneously, or maybe I'm missing something.

So how do I determine the best location (L1 distance) for the feed point in my initial PCB design ?

And how do I trim the resonant to say 868MHz and also the impedance to 50ohm ?


texts:
I'm trying to do a summer in VHDL, but when I try simulate, appear an error.
The code:
library IEEE;
use IEEE.Std_Logic_1164.all;
entity aritmetico is
port (A: in std_logic_vector(2 downto 0);
 B: in std_logic_vector(2 downto 0);
 Control: in std_logic_vector(1 downto 0);
 Out_hex: out std_logic_vector(6 downto 0);
 Out_bin: out std_logic_vector(3 downto 0)

 );
end aritmetico;

architecture circ of aritmetico is
 signal F,G,F1,F2,F3,F4: std_logic_vector(3 downto 0);

 component sum is
 port (A: in std_logic_vector(3 downto 0);
 B: in std_logic_vector(3 downto 0);
 F: out std_logic_vector(3 downto 0) );
 end component;

 component decoder is
 port (C: in std_logic_vector(3 downto 0);
 F: out std_logic_vector(6 downto 0)
 );
 end component;
 component mux4_1 is
 port (F1,F2,F3,F4: in std_logic_vector(3 downto 0);
sel: in std_logic_vector(1 downto 0);
F: out std_logic_vector(3 downto 0)
);
end component;

begin
 F1<= ‘0’ & A;
F2<= A & ‘0’;
F3<= ‘0’& B;
F4<= B & ‘0’;

sum: Sum port map(F1,F,G);
decod: decoder port map (G, Out_hex);
 multip: mux4_1 port map(F1,F2,F3,F4,Control,F);
G <= Out_bin;

end circ;

How can I solve this?


texts: Counter torque in alternator supplying reactive power

texts: When an alternator(assume zero armature resistance and iron loss) is supplying purely lagging/leading current, which means there is no work done by the current supplied, does that mean the counter electromagnetic torque offered by the alternator is theoretically zero?


texts: MOSFET: how to determine if a heatsink is required?

texts:
for a given mosfet, how do I know how much current can it handle without a heatsink?

I could just play it safe and add a heatsink + fan but the controller board am using doesn't have mounting holes for any pcb mount heatsink. It is fused but I just want to be sure.

So for example  If I was using a mosfet as a switch for a 360w load and it's 0.31 degree c per watt then in 25degrees c air it'll be

0.31 x 360w = 111 degrees c!!!! based on a IXFH52N30P as a example

If for example I was stupid enough to not use a heatsink then it could termally runaway due to the mosfet rasing the amient temperature right?


texts:
I'm searching the way to measure rotational displacement by using Euler rotational matrix.
And I could find various information about it.
Then I've found something wrong with reference axis.

In the figure C, it indicates that the reference axis of second rotation is x'-axis not x-axis.
But the matrix is,

The matrix means that the reference axis is the x-axis.
For example, if we assume the point (1,0,0) is rotated in that method for (phi,theta,psi) = (45 degrees, 45 degrees, 0 degrees), we can calculate it by using those D, C matrix. Then the result is point (0.7071,-0.5,0.5). It means just what I mentioned(except sign coincidence with the first picture). The reference aixs is x-axis not x'-axis.
I'm confused because of this problem. Please let me know what is wrong.
Thank you.


texts: SiC MOSFETS power dissipation; for heat sink sizing

texts:
I want to calculate the max. power dissipated for SiC Mosfet in a 6.6KW CLLLC resonant converter with full bridges on primary and secondary sides.

Let's consider the case when the input voltage is 400 VDC the output voltage will be 300 V. The MOSFETs on the secondary side will dissipate more power.
I guess we can multiply the R.M.S current by 2 SiC MOSFETs \$ Rds_{on}\$, this gives the total power losses on the single side of the converter.
Pd = \$ I_{r.m.s}^2 \times  2 . Rds_{on}  \$
1-Can you illustrate how the max power dissipation is calculated for a single SiC MOSFETs assuming max efficiency(the value to use for heat sink sizing for a single Mosfet not four MOSFETs), and how can I calculate switching losses.
MOSFETs Rdson=0.035 ohms. datasheet from here
2-The max current value on each leg; which is to be used in trace width calcualtion?
Thanks in advance.


texts: Current booster with LM317 not working properly in LTspice simulation?

texts:
I was playing around in LTSpice with this "current booster" circuit I found on this paper but it doesn't seem to work as I expected.

I set up R2 and R3 in order to get a Vout of about 14.82V. If we neglect the voltage drop on D1 (just for this example's sake) and fix R4 to 14.82 Ohm then I would expect around 1A flowing through R4. But that's not exactly what happens, instead Vout drops to about 12V, through R4 there's about 0.8A which is fine, and Q1 is basically useless since almost no current flows through it. If I try to get more current through R4 the result is that Vout goes down even further and Q1 doesn't turn on.

I expected Q1 to turn on and Vout to stay close to the expected 14.82V. Why is this not happening?

I simulated the circuit both here and LTSpice so I think I might be the one missing something.

simulate this circuit – Schematic created using CircuitLab

EDIT:
I looked a bit on the datasheet and at page 17 there's a circuit that does the same thing as the one that I proposed above and it works fine in LTSpice. If you don't mind the fact that Q2 is dissipating about 33W (ie probably frying) the circuit works as expected: the voltage right before D1 is about 14.80 V as expected and about 2.8 A flow through R4. Here's a picture of the new circuit:


texts: How does a MOSFET conduct in saturation region?

texts:
It is a simple question but I could not find a straightforward answer.

When a MOSFET enters saturation region, the channel length starts to decrease, and the channel width is the smallest near the drain (assuming conventional current flow from drain to source). This smaller channel width causes the current density to increase, and hence a strong electric field now exists between the thinner end of the channel and the drain.

This strong electric field can assist the motion of charge carriers and hence enable conduction. But is this electric field the only factor that supports conduction in the saturation region? If so, how does this conduction almost without the presence of a channel (for a small distance) not increase the on-state resistance?


texts: Max Voltage for Speaker of Given Power Rating

texts:
I have been looking into the design of loudspeaker drivers and would like to know how to determine the maximum voltage which can be delivered to a given speaker.

From Ohm's law we know that P = V^2 / R. Therefore with for a speaker of any given power rating it would seem that max voltage could be determined by the formula:

V = sqrt(P * R)

Therefore for an 8ohm speaker with a power rating of 10 watts, it would seem that max voltage is around 9 volts. (sqrt(8 * 10 = 80) = 8.944 ~= 9)

What I'd like to know is which voltage measurement this refers to out of the following:

-Peak (where the speaker could handle a range of 0v -> 9v)

-RMS (where the speaker could handle an RMS value of 9v)

-Peak-to-peak (where the speaker could handle a range of -9v -> 9v)

If anyone could clarify this for me I'd greatly appreciate it.


texts:
I have an Arduino Uno with a WiFly shield. I want to use 5 PWM ports on the Arduino to control motors, but some of the PWM ports are used by the WiFly. Looking into it I think I need to use the SPI bus but I'm not sure if this is possible with the WiFly shield or how to go about it.

I'm not sure how I'm supposed to wire the motors so that they can work alongside the WiFly.

If you could point me to a tutorial (I haven't been able to find one similar enough to my case to understand) or if you could give me some pointers, that would be great.

Thanks.


texts: Alot of TDRs use square waves or needle like pulses for length determination. Why are not other pulse shapes like sine or triangle used?


texts: Is galvanic isolation of Hi-speed USB impossible?

texts:
I have a USB isolator which provides galvanic isolation of a USB device from my PC, but only works for low speed and full speed USB. I can't find any alternative electric isolators which do provide Hi-speed connection; USB fiber extenders, however, are offered with hi-speed throughput and should provide both galvanic isolation and high bandwidth, though perhaps at higher cost?

Is there a practical or physical limitation to the bandwidth of a galvanic isolator for USB? Are actual laws of physics involved, or is this merely an engineering challenge or cost issue?

Edit

Let me rephrase my own question:

Non-fiber USB isolators cost about €100 but are limited to full-speed USB.
Hi-speed USB isolators do not exist, so I assume they can not be made for €100, but would cost significantly more (€1000? €10000). At such a price, there is no market, thus there are no hi-speed USB isolators available.

The question thus is this:
What makes a hi-speed USB isolator so much more expensive than a full-speed USB isolator? Is there a physical limitation to the approach used for the full-speed devices which makes it inapplicable and/or cost prohibitive for hi-speed devices?


texts:
I built a solar panel charge controller from instructables with an easy to read schematic and for some reason my battery charges up to a certain point and then loses charge again. That leads me to ask a couple of questions given that i am very new to this.

My Setup:
    10W solar panel, 12v7A Lead Acid Battery, Arduino Nano and all components from above schematic except for the load at this point.

More details on solar panel specs: Solar Panel 10W • Vmax P = 17.2V • Imax P = 0.57A • Voc = 21.6V • Isc = 0.83A • 396x348x25mm

Before I connect my solar panel my panel's voltage sits around 20volts (with volt meter) but straight after I connect it to the circuit, the voltage drops. Is this because there is now current and that reduces the voltage?
At a certain point (around 12.4 volts) my battery stops charging and actually starts losing voltage. Could this be because the current supplied from the solar panel is not enough to charge the battery? If not, any other ideas?
Does it make sense that the Arduino, solar panel, batteries and output voltage ground are all connected together?
At what voltage would I actually charge my batteries when in bulk charging mode (99% pwm)? Does it have to be more than the current voltage of the battery and by what margin?

Thank you very much for the assistance and please bear with me, I am new to this.


texts: I am studying comparators and Schmitt triggers. And I did not find anywhere how to choose the value of hysteresis. I understand its purpose and I know how to calculate it. But what value is needed for a particular scheme? Is any rule to choose that value?


texts: Using a modified non-proprietary battery for CPAP

texts:
My apologies if this isn't the correct place for this question. I am not familiar enough with some of these concepts to move forward on this without bouncing the ideas off of some more experienced people.

I have this CPAP (medical device for sleeping): https://mytranscend.com/wp-content/uploads/2018/09/103347-rev-l.pdf

They sell a battery for this that costs more than I'd prefer to pay, and can only be used for operating this CPAP. I was hoping to gain some versatility and save some money with a non-proprietary battery for this.
This is all on pg. 34 of the above link. The AC adapter for the CPAP is rated for an output of 18 VDC, 1.67 Amp, and the batteries are rated for an output of 14.4 VDC; at least this is how I interpret the manual. Can I power this CPAP with something like this: https://www.amazon.com/Poweradd-Pilot-Pro2-Notebooks-Smartphones/dp/B015OAJFOC/ref=pd_sbs_107_2?_encoding=UTF8&pd_rd_i=B015OAJFOC&pd_rd_r=SZEFWNV0SN48T70QDKDZ&pd_rd_w=Q7LzD&pd_rd_wg=vYYR3&psc=1&refRID=SZEFWNV0SN48T70QDKDZ? I don't think this battery has the right connector, but I thought I could create an inline adapter that will connect one of the existing battery connectors to the connector type on my CPAP. My DC barrel connector has (roughly) a 6 mm outer diameter, a 4.33 mm inner diameter, is roughly 9.9 mm long, and has a pin on the inside of the cylinder that I can't reach to measure with my calipers. After a little bit of research, I think it might be an EIAJ-05 connector.

With my lack of knowledge in this area, here are some of the questions that I could use some help with addressing:

With a power cord that outputs 18 VDC, 1.67 A, and a battery that outputs 14.4 VDC, will one of the native settings on this battery (5V/9V/12V/16V/19V/20V) power this CPAP if I can create a working inline adapter?
If none of the native settings are a good idea, can I add power diodes to my inline adapter to drop the voltage down to an acceptable amount?
Provided I can find the correct connector for my CPAP, are there any flaws in the plan to build a small inline adapter to connect one of the existing battery connectors to my CPAP's connector?
Am I overlooking anything with this idea as a result of my inexperience and lack of knowledge?


texts: Identify this connector? (3 pin, similar to JST)

texts:
Can anyone identify this connector?
I removed it from a digital door lock as one of the leads had become uncrimped. Ideally I'd like to buy a replacement with 3 wires/leads crimped on.
I already checked the JST connectors, and I can find some that are similar, but none identical - the single central rib on one side is the feature I can't match. I looked on Digikey, but could not find it (but I'm not very familiar with their system)
Counting pixels, I'd assess the pin pitch to be 2mm. (US penny is 19mm)

Thank you


texts: Zener diode in stepper motor driver with TPL7407L

texts:
In TPL7407L's datasheet, there is a stepper motor driver schematic as below

There is a zener diode denoted as "optional". However the 'COM' pin is connected to 'VSUP' directly. The 'optional' means I can remove (not short!) it, right? Then what's the purpose of the zener?


texts: How can I get shocks while charging my phone in the train?

texts:
Ever since I got a phone with a metal chassis I get this issue : if my phone is plugged to a train electric outlet and I simultaneously touch my phone and any metallic part of the train (such as an ventilation grid) I get a small, but painful jolt.

Now, as I understand it, insulation between the phone chassis and the train should be provided by

the train electric supply system
the charger's transformer
the separation between the phone's battery and chassis

So why do I get those shocks ?


texts: How did old WW2-era radars accurately measure time delay and integrate this into an oscilloscope?

texts:
The speed of light is about 300,000 km per second. An error of just 1 ms would result in being off by about 300 km, which is far too much error for a radar. I would guess it needs accuracy on the order of 10 microseconds in order to get range accuracy of 3 km.

What I want to know, though, is how microsecond accuracy is integrated into an oscilloscope so that a human operator could visually notice a difference of 1 ms. What was the translation? E.g., 1 microsecond difference puts the blip 10 millimeters away? I understand an oscilloscope translates a signal into voltage, but what I don't get is, how is the time delay processed and shown on the screen? Did this require vacuum tubes?


texts:
I have the following setup:

480V, 200A service fed into PWM Drive, Drive output going to 1000kVA step up transformer (8.4 ratio) feeding a 2380V/53A 3phase induction motor. The motor is UNLOADED.

When running at NP, I measure (with multiple devices) 477V/28A into my drive input. I measure roughly .65 pf

However, I push 283V/158A out of my drive to reach my NP motor voltage and current requirement. I don't have a PF but I imagine it's somewhere in the .13 range.

S = sqrroot(P^2 + Q^2)
P = VIcos(theta)
Q = VIsin(theta)
(might be forgetting the 3)

IN
P = 8681W
Q = 10079VAR
S = 13302 VA

OUT
P = 5812W
Q = 44278VAR
S = 44657VA

By my calcs, I cannot figure out how this is possible. The real power (W) is accurate if you account for losses, but the apparent power (S) proportions are way off. I'm stuck believing it's a function of the drive but is there an explanation or a next step to take to conform this?


texts:
I have these smartphone headphones and I am trying to replace the 3.5mm headphone jack. I purchased a replacement jack and then stripped back the wires on my headphones to see this.

I was not expecting the red and white twisted cable (on left of photo) but I imagine that's the cable for the button on the headphone cable.

I have my soldering iron ready, but what am I soldering?


texts: I heard that it would be possible to detect if a device connected to the uart is turned on with the help of the tx line. How does this work? I only know that the rx line is standard pulled up.


texts: Change Default Altium Footprint Part Designator Top Overlay Text Size

texts:
I got an Altium question.  I'm trying to speed up my Altium workflow.

Everytime I Design > Update Schematics, when I import all the footprints into the .PcbDoc the part designator overlay text is way too big.

Usually I go through PCB Filter > PCB List and manually set the text size for the designators by hand.

That's getting old, and I'm getting better at Altium.  Time to take it to the next level!

Where is that default text size parameters coming from?  How can I just have the part designator text be the size I want whenever I update a schematic?

Thanks!


texts: Siglent SDS1104X-E Integrate Function - Units of Measure

texts:
I am using a Siglent SDS1104X-E four channel oscilloscope which has a variety of math functions, one of which is to integrate a signal.
Currently I am measuring a voltage pulse across a gate resistor which invariably feeds the gate of a MOSFET.  I want to determine the area under the voltage curve and use it to calculate the equivalent current (in terms of area, not peak value) using the measured resistance value.
Here is the wave form for which I would like to integrate (section isolated using the gate function).

When I set up my scope I am guessing that the resulting integrated waveform is representative of the area under the measured curve versus time, is this correct?  I am assuming that the peak value of this curve is the total area under the measured waveform.  What confuses me is the unit of measure for this resultant waveform... uWb.  After some searching I can only assume this is micro-Webers, which apparently converts 1:1 to microvolt-seconds.  Is this a correct assumption?  If so, why is the scope measuring in uWb and not uv-s?
Next, how do I make use of this value to calculate current if the resistor is 36.18 Ohms?


texts:
So recently I was experimenting with some 100W LED's (30-35 VDC @ 3A) and a "1200w" DC-DC boost converter that goes up to 85V.

While at an input of ~12 VDC and an output of ~26 VDC, I accidentally shorted the output, and the main MOSFET blew and is now shorted out.
I un-soldered it from the board, to see the model, but while I was able to find the spec sheet, I was not able to find the MOSFET for sale for a reasonable price (and I only need one).

I put another MOSFET that I had laying around in it (I don't know the part number), and it worked, but I'm almost certain that it isn't rated for such high voltages, as it was creating a lot of heat (no load) at anything above maybe 30 VDC and started dropping when it got to ~70 VDC.

The boost converter is rated up to 85 VDC (which is the limit of the original MOSFET).

Out of a random moment of insanity, I purchased a IRFP4468 which is rated for a slightly higher voltage (100v VS the 85 of the original) and a higher amperage.

The original MOSFET is an NCE85H21TC

Will the IRFP4468 work in place of the original MOSFET, or did I waste my money?

I followed where the pub goes and traced it in the included picture. I don't have the schematic and drawing it by hand would take days.

The converter had two 15A fuses in parallel in the input, but I bypassed them and enlarged the positive rail with more solder, as it was heating up and causing a voltage drop. I'm pretty sure that even without the bypassed fuses, the MOSFET would've died, as the cables I was using are extremely thin, about half of a spaghetti noodle, including the coating, so I'm sure I wasn't passing the ~15A output needed to run through those cables in order for the 30A input fuses to blow.

Thanks for the help in advance.

GATE DRIVER PICTURE TRACED

IRFP4468 DATASHEET


texts: How was the transformer reduced in this Thevenin equivalent circuit?

texts:
Below is an example of a one-port network and how to find its output impedance by using Thevenin model:

I can understand that Vi is set to zero since it is an independent source. But how was the coupled coils or transformer with 1:a ratio is reduced to the third circuit diagram? I mean how was a^2*R1 and a^2*L1 was obtained? Only the ratio 1:a is given not the inductance.


texts:
I have the set up as shown in the picture below, The stepper Motor is supposed to drive the water Container Up and Down , stirring the solution in the container.
My stepper Motor is a Nema 17 and I'm using a TB6600 driver for micro-stepping.

I don't know if my motor holding torque is too small, or the gear set up is not done properly, because the motor is struggling to drive the container up and down when 400mL of water is thrown is the container.
Can someone help me with calculation for the right Torque to carry this load.
The Overall load is about 600g.

Note: The system works when the container is empty.


texts: Digikey like parametric internal parts search software

texts:
I am looking for software that  essentially duplicated digikey/octopart's parametric parts search, but filters on an internal parts list that we already have.
Is there any commercial or open source software that accomplishes this internal electronics parts search?
Ideally self hosted.
There are many an electronic parts catalog (EPC) software, but none really seem to have parametric search down, especially for electronic components specifically.


texts: Low power radio + microcontroller recommendation?

texts:
I'm searching for a low power system-on-chip that combines:

A processor (any achitecture)
A radio (any frequency/bitrate/tx power)
2 or more I/O pins (ADC would be a bonus)

Can anyone recommend a device?

Which chip companies should I be looking at?


texts:
I know this might be a little bit funny question. But how can you determine the current that will used up as well as the power rating, when you a designing a power supply unit for a device. Because usually, I will always know the voltage, say 5V, but how can I calculate the current the device will use up.

Thanks.


texts: Is the discharge rate for all AAA batteries the same?

texts:
Just a simple question regarding battery hype.
Given 10 brands of readily available AAA batteries, is the discharge rate going to differ between them given the same load for the same period of time?
I understand shelf life can differ. But will they all store the same amount of power and discharge it at the same rate?
Thank you. Just a question to assist in judging brand value/$ on use rather than non-use.

Added:
All the answers kill the layman theory of “...all built in the same factory, all the same, you’re paying for a name.”
Interesting that eight times more expensive battery brands are not eight times better in performance.
Again, thanks so much for the great answers! Very impressive and most helpful.


texts: Recommened chips for datacommunication over a low-voltage AC power line?

texts: A client wants to send data (think 100 ... 10k baud) over a combined power / cable-TV coax cable, distances up to 1 km. The lower end of the spectrum (say up to a few MHz) is free, but the cable carries the 50 Hz 48 .. 60 Volt power. What would you recommend for this? I was thinking power-line modem chips, but those seem to be out of fashion (and hence difficult to get), and require quite a few external components. A DIY approach could be to couple a modulated carrier into the line and detect it with a PLL chip or even a PIC with DFT. But I hope chips exist for exactly this purpose?


texts: How do I determine the parameters for a battery equivalent model?

texts:
I have these pieces of information of a battery from which I want to estimate the battery equivalent RC parameters. Let it be first order or second order.

I have a performance curve detailing battery cell voltage with respect to time for varying CRate (e.g C1 C3 C5 C10). Also battery Capacity and Nominal voltage. Charging characteristics recommended parameters like (Float voltage, boost voltage, equalizing voltage, etc.)

I do not have pulse testing data.

I want to find the RC Equivalent of the battery from its performance curve. Any thoughts ?


texts: Does the "Avoid using floating-point" rule of thumb apply to a microcontroller with a floating point unit (FPU)?

texts:
As a rule of thumb, I try to avoid using floating-point in my embedded system codebase.

Floating-point variables are:

Computation-intensive
Not atomic (can cause problems in an RTOS application or with interrupts)
Their precision can cause non-obvious behaviour (float comparison problem).

But what about a microcontroller with a floating point unit (like the STM32F4)?

Do those concerns still apply? Would you still advise against using floating-point?


texts: Digital Communication \$T_x\$ and \$R_x\$ for Dish - Coaxial Cable - TV Setup

texts: I have a question in mind regarding transmitters and receivers. Let's say we have a dish then a coaxial cable connecting our dish to the TV. Can we consider the Dish as a transmitter \$T_x\$ and the TV coaxial input as the receiver \$R_x\$ ? Will the signal passing through the coaxial cable (our channel in that case) be simply the analog electrical signal but amplified? Or is there some intermediate processing?


texts: Is it possible to drive an arduino nano and a 5v solenoid via usb?

texts:
So basically i want to make a clicker with a solenoid like an old school IBM keyboard. What i'm thinking is to put and arduino nano and the smallest 5v solenid i can find inside my keyboard and internally connect the usb power lines to the arduino and the solenoid, but i'm worried it'll be enough power consumption to fry a usb 2.0 port. The arduino nano uses around 19mA and my keyboard 100mA. I'm an absolute noob when it comes to anything other than coding (i do know how to solder propperly tho).
Edit:
Thanks for your comments, i think i'll be doing exactly as i said EXCEPT i'll use an external power supply for the solenoid/arduino and investigate on how to make a propper prottection circuit so that i don't accientally fry my arduino or my keyboard.


texts: I have an amplifier circuit. Is it a problem if the input*gain is higher than the VCC? so at some moments i have 3.3V on the +. I see it caps to 11V in my simulation but do i damage the component?


texts: MOSFET gate spikes when load is disconnected

texts:
I have a system that has two fan banks driven by MOSFETs. The fans are mounted on two sides of the enclosure on ~2 ft cables. After one second from system turn-on the microcontroller turns these FETs on. When the fans are already connected before system turn-on this is no problem.

What has been seen is that if the fans are disconnected during operation the system will reset. Also, if the system is running with the FETs powered and the fans are connected the system can reset. This is not consistently reproducible.

There are positive and negative spikes on the gate from -3V to +9V. I'm decently confident this is what is killing the micro and causing a reset. What I don't understand is how there can be a significant energy burst when the inductive load is removed from the system. Just to be clear the state of the FET is NOT being changed by the micro - there is no turn-off/turn-on control - only installation or removal of fans.

simulate this circuit – Schematic created using CircuitLab


texts: VHDL: Looping through a module asynchronously

texts:
I have a VHDL module that applies a shuffle algorithm to a 64 bit input and outputs the 64bit result.

I need to loop this output back through the module exactly 4 times, i was wondering if there was a way to do this asynchronously, or do i need a clock and counter to make this work?

Thanks.


texts: What is the analog pin for on a Phidget 3051 Dual relay board?

texts:
I recently purchased a Phidget 3051_1 Dual Relay board with the intention of using it to switch on and off flourescent lamp ballasts (20W tubes) over a fish tank by connecting the relays to 110VAC and using an arduino on the control inputs. What I'm not quite sure about is the purpose of the analog input pin on the power connector. I think I can safely ignore it.

Is there any benefit I would gain by using the analog pin on the 5V power harness?

Also, do I need to worry about load noise from the ballasts?


texts:
I am writing my Very First Verilog Program Ever: I'm trying to capture intervals between incoming pulses. I have a sample clock, an asynchronous pulse source, and the output is a registered 8-bit byte and an interrupt line; every time a pulse arrives, I assert the interval in the range 0x00-0x7f on the output and twiddle the interrupt, and a microcontroller DMAs it into memory. (The context.)

That bit works fine. The complication is that if a pulse doesn't arrive by the time my internal counter rolls over, I emit a 0x80 byte. The intention is that long intervals are to be represented as multiple bytes.

What I am finding is that intervals in the 0x00-0x7f range work fine, but longer intervals emit complete garbage. The logic looks very simple to me, so there's obviously something I'm not getting in the way Verilog works. Anything here look obviously wrong?

My constraints are:

the input signal is not aligned with the sample clock, and each signal may span multiple clock ticks. I only care about the rising edge.
interrupts are edge-triggered but there's a delay between the interrupt and the DMA read. I do appear to need the latch on result to ensure the result remains asserted.
I know there's no reset, I'll do that later.
this is on a Cypress PSoC5LP development kit, which uses a cut-down version of Warp Verilog. I did try to use EDA Playground to simulate it, and it all seems to work there, but it doesn't work in real life.
in real life, my sample clock is 12MHz and an input pulse can be anything from 150ns to 500ns.
there may actually be nothing wrong and I'm hitting hardware constraints in my pulse generator. Which isn't confusing at all.
Update: my hardware can't generate pulses closer together than about 750ns, which is about nine sample clocks, so I don't think I need to worry about pulses coming in in successive clocks. Update update: no, that's rubbish. Pulses 0x81 ticks apart will need to generate two bytes, 0x80 and 0x01, one sample clock apart.

module Sampler (
    output reg interrupt,    // a pulse has been detected
    output reg [7:0] result, // output data byte
    input clock,             // sample clock
    input sample             // incoming signal
);

reg [6:0] counter;   // monotonically increasing counter
reg last_sample;     // for sample edge detection

always @(posedge clock)
begin
    if (counter == 0)
    begin
        // Rollover.
        result = 8'h80;
        interrupt = 1;
        counter = 1;
    end
    else if (sample && !last_sample)
    begin
        // A sample happened since the last clock.
        result[6:0] = counter;
        result[7] = 0;
        interrupt = 1;
        counter = 1;
    end
    else
    begin
        counter = counter + 1;
        interrupt = 0;
    end
    last_sample = sample;
end
```


texts: Can a charged 120v high voltage capacitor really kill you?

texts:
recently I have been hacking few psu and have to deal with some high voltage caps. It sort of scared me, but thinking about it, what is the chance of it really killing me.

Is it safe to touch one terminal of a charged and opened 120v cap? I mean the other terminal is opened, and connected to nothing, so there is no current flow, so it should be safe.
Touching 2 terminals of a charged cap with one of your finger will give you a shock in your finger, but since no current go through your heart, it will not kill you. am I correct?
The only scenario a charged cap could kill you is when you touch one terminal with one hand, and other terminal with other hand, and the shock go through your heart. but still, what is the chance of that tiny 120v killing you if you are a health person. I think doctors use high voltage to save people.

Is a tiny 120v charged cap really that intimidating?


texts:
I wish to attach a board camera and display to an fpga and have an interface to a pc implemented.

This would need to be at least usb2 speed for video.  What is necessary to implement usb on an fpga?  Are there any IC's I should consider?  Perhaps something like firewire would be better or even gigabit ethernet?


texts:
I'm trying to work out why someone would choose the right circuit over the left one.  The only thing I can think of is, that one on the right can be made an adjustable current source by making \$R1\$ or \$R2\$ a pot.  If using the circuit on the left, how does one know what to set the voltage at the base of the BJT to?  I would've thought one would set it as high as possible so that it is \$V_B \gg V_\mathit{BE}\$.

simulate this circuit – Schematic created using CircuitLab


texts: Duty cycle detection circuit for square wave

texts:
I have two signals coming out of one block. One signal is one period delayed than the other one. Is there any method to detect the duty cycle of these pulses?.

Edit:
Clk is my original signal. Going to two blocks . Have two outputs clk_1 and clk_2. Having different pulse width compared to the original signal. I want to detect if such a case is happening. That is if the duty cycle of the two signals coming out is different to the original signal.


texts: Why do carrier waves sound silent on radios?

texts:
I was recently reading about and building low-power AM radio transmitters, and read/noticed that when the carrier wave is not yet modulated, the radio receiver goes silent.

For example, let's say my transmitter transmits at 1000 KHz. Before the transmitter is turned on, the receiver picks up the local radio station that also transmits at 1000 kHz. However, once my transmitter is powered on (but not modulated), the radio receiver becomes silent.

Why does this happen? I'm curious about the mechanics of the speaker. Does the speaker vibrate at the 1000 kHz frequency, and we just cant hear it because it's out of our range of hearing? Or does the speaker cone expand outwards and stay there? Or, does it not move at all? I had a lot of difficulty finding information about this online, so any help is appreciated!


texts: Blocking wait for pin change on a LPC1114 microcontroller

texts:
I need to synchronize the rising edge of a PWM with another signal pulse's falling edge on a LPC1114FN28 (trying to drive a TCD1304DG), but am failing to achieve this so far. I have tried the following:

while (LPC_GPIO0->MASKED_ACCESS[ClockMask]);    //wait for the clock to go low
while (!(LPC_GPIO0->MASKED_ACCESS[ClockMask]));   //wait for the start of PWM cycle
LPC_GPIO0->MASKED_ACCESS[ICGMask] = 0x0;   //make the ICG pin go low

where the ClockMask is a mask of the corresponding PWM pin, running at 1MHz  frequency, 50% duty cycle and ICGMask a mask of the pin I'm trying to synchronize with the PWM.

The strange problem I encountered is that one of the two whiles seem to block forever for some reason and any code after them does not get executed. When I remove them, it works OK.
This could be probably caused by the instructions for the while lasting the same as is the PWM period and thus the condition would always see the pin in the same state, but that seems rather improbable to me...

I am running the chip at 48MHz from the IRC and the PWM measured with my oscilloscope is practically flawless.

So what could I be doing wrong? Is there any better way to do this? Would writing this part of code in assembler help with the timings (they need to be pretty precise)? If so, is there any tutorial for this?

Thanks in advance for any answers!

Edit:
Even using interrupts I was unable to get sufficiently invariable results - the timing of the interrupt after the pulse edge changes. I will try more methods...

Other methods did not work at all. This is probably simpy unachievable, but I do not know, what else could I be doing wrong if not the timing (as the Toshiba CCD is still not responding).


texts: Verilog: Pass a vector as a port to a module

texts:
I have two modules

counter: Output is a vector called error_count.
lcd: Module to display the code on an LCD. Input includes clock and error_count.

Following snippet of the code is most relevant and attached below:

Top level module:

counter counter1 (..., error_count);
lcd lcd1 (..., error_count);
counter module:

module counter (..., error_count);
...
output reg [31:0] error_count = 0;
... //Update counter every clock cycle
endmodule

lcd module:

module lcd (..., error_count);
...
input [31:0] error_count;
... //error_count used to display on LCD
endmodule

What is wrong with this code? The display just prints 0 as the output. Is there anything wrong with the way I am passing the the vector?

Additional Info:
I am using the Xilinx Spartan 3E starter kit for testing this code. The LCD code is fine and I have tested it with local counter (which was reg[31:0]).


texts: Noise suppress recommendation and best practices

texts:
I've developed for my home automation project this schematic: it's quite simple, an ESP32 GPIO enable pin drives those mosfets that gives power to the LED and enable the PCA9306 EN pin, for more specific info, refer to my previous question here.

I'm not an expert in electronic engineering and design, so I need help finding some errors (if there are any) in my circuit.

As far I know, the 330 ohm pull-up resistors are so low in order to compensate the total cable capacitance (of length 30 meters).

The circuit works, but sometimes I've got I2C errors on bus, do you guys have some hints about this simple schematic?


texts: How to calculate the phase shift between the voltage and current in a RC circuit

texts:
The question asks:  A voltage of the form \$V=V_0 sin (ωt)\$ is applied across the network. Evaluate the phase shift between the voltage and the current flowing through the network. State whether the current leads or lags.

I've found the complex impedance - it is \$ Z=R + 1/jwC\$ where j is the imaginary unit, w is the angular frequency and C is the capacitance. I then found the modulus and angle of this impedance. However, I don't understand how I can relate this to current and find the phase difference.

Phasors confuse me as I'm not sure whether I should be taking the length of the voltage vector into account when calculating the angles. The complex exponential method, representing V as \$V_0e^{j(wt)} = Z *I_0e^{j(wt+\phi)}\$ confuses me as I don't know how to find Phi, with two unknowns \$ I_0 \$ and \$ V_0 \$ there.

My ultimate issue is that I'm receiving differing information from different sources. Some youtube guides are suggesting things different to my textbook. Guidance would be appreciated.


texts: Relay contact insulation doesn't seem to be enough

texts:
I'm working with an ESP32 and a 4 relay module. The problem seems to be that the insulation of contacts in the relay is not enough.

Relays close perfectly and my lights turn on, but when they open, a 20V or less voltage remains between the main contact and the normally open contact, enough to faintly turn on my lights. As you can see, my lamp is connected to the normally open contact of the relay. I've considered adding a resistor in series with the lamp to drop the voltage, no luck so far.
The datasheet corresponding to the part number:
https://pdf1.alldatasheet.com/datasheet-pdf/view/114955/ETC1/JQC-3F.html
In my case the manufacturer is BESTEP but the part number is the same, JQC-3F-05VDC-C.
Regarding the lamp, it's 5 parallel 50 watt COB LEDs. Couldn't find the datasheet.

This faint light is greatly undesired. Any clues as to how to work around this?


texts: Accessing MCP4451 Digital Pot with STM32 using HAL for i2c?

texts:
I am using an STM32 NUCLEO-F042K6 dev board to interact with a MCP4451 digital pot. I want to be able to adjust the wiper values through i2c. I am using the STM32CubeIDE and the HAL library to interface.

 static const uint8_t POT_ADDRESS = 0x58;
 static const uint8_t INCREMENT = 0x94;

  while (1) {
  buf[0] = INCREMENT;
  ret = HAL_I2C_Master_Transmit(&hi2c1, POT_ADDRESS, buf, 2, HAL_MAX_DELAY);
  if (ret != HAL_OK) {
      strcpy((char*)buf, "Error Tx\r\n");
  } else {
      strcpy((char*)buf, "YEET\r\n");
  }

  HAL_UART_Transmit(&huart2, buf, strlen((char*)buf), HAL_MAX_DELAY);

  HAL_Delay(200);
  }

I have the correct configuration, but I keep getting "Error Tx" on the serial monitor. I made sure to power the i2c lines with pull-up resistors to 3.3V. I'm a bit lost as to what to do.


texts: How do I get a relay to recognize when a TRRS jack is plugged into my iphone?

texts:
I'm working on a project where I would like to put an aux input in my car.  I was thinking of hooking up my CD changer output wires to a relay and then hook up the aux wires to the other part of the relay.

The part that I'm getting stumped is that I would like to have the relay switch automatically when I plug the jack into my iPhone, and then when I unplug it, it would go back to the CD changer.  I'm trying to avoid hooking up a mechanical switch to drive it.

I was wondering is there anyway that this is possible?  I have the idea but just not sure how to execute it.  Any help would be great!


texts: How does the sound card process different incoming audio signals before outputting to the same speaker simultaneously?

texts:
Below is a primitive representation of audio flow in a PC:

simulate this circuit – Schematic created using CircuitLab

A program executes a code, after many steps in binary/transistor level finally the audio is sent from the CPU to the soundcard in digital domain. The sound card then processes this incoming information to analog signal and amplifies and outputs to a speaker.

Knowing that the CPU is a serial processor, how come we can still hear several different sounds from the speaker as they are distinct. Somehow the soundcard does not mix simultaneous incoming audio data. And most confusingly imagine one executes three programs where all outputs different audio. But at the end there is one single current passes through the speaker.

What is that current composed of? Is that the addition of three different waveforms? If so are they added in soundcard or before? Is sound card parallel processing and adding them at the end?


texts: Dealing with signal noise over 50 foot communication link

texts:
Situation: Connecting a motor controller to an MCU.  Motor controller is about 50 feet away from MCU.  Connected via a single conduit (buried), containing the following cables: (There is no other electrical equipment in the area, and this is outdoors between two weather-proof boxes.)

24VAC power to motor controller (#14/2) (60Hz)
Cat5 cable (24AWG copper)

Signals being transmitted to MCU:

Motor direction signal.  This line is pulled high or low depending on the direction of the motor.  No fast changes: motor runs one direction for at least 10 seconds.
Motor position indicator.  A TTL-level square wave (100Hz to about 1kHZ) outputting a number of pulses per revolution of the motor.

The problem:
Signals arriving at the MCU are very noisy - you can see the 60Hz line interference clearly - and you can see crosstalk on the two lines - the Direction signal is pulsing along with position indicator square wave.

Any suggestions how to clean up these signals to be usable?

I could possibly put a second MCU inside the motor controller box, but what protocol could I use to transmit across the existing Cat5 cable that would not be as susceptible to this type of interference?  Would prefer I2C... suggestions? Hoping to avoid CAN bus as it adds too much complexity and extra hardware.

Any suggestions appreciated.


texts: Manually selecting which of three ethernet output ports should transmit signal from a single ethernet input, using MCU and transistors?

texts:
I have a TV-bench containing three different computer units that all use Ethernet. Although, I only have one measly ethernet output coming out of the wall closest to the bench. Not wanting to clutter my apartment with long ethernet cords, I thought that maybe I could make an MCU powered switching system that allows me to manually switch which unit should use the ethernet by the push of a button.

My idea is as follows:

Select ethernet output with pushbutton that corresponds ethernet output port 1 - 3.
MCU sends signal to each base of the transistors connected to the desired output port.
Continuous signal established between input port and selected output port.

I realise that I may be using the transistors wrong, but I'm just curious if my idea would even work, so don't hate lol

My main concern is whether or not you can create paths between ethernet ports this way. I've read this post which sort of touches the topic, but I'm not completely sure me and the OP of said post want to achieve the same thing.


texts:
the below circuit triggers with 0.05 volt, even if touched the base of 2N3906 the circuit triggers ,
what is the issue or alteration to be done to fix the circuit to work only at 0.5volt or higher is applied on the signal pin.


texts: How do 24v or 48v solar/battery inverters provide power for houses that rely on 110v?

texts:
I've been learning about solar systems and I keep seeing that the systems feed power in to batteries, which is then fed in to the house via an inverter, typically 24v or 48v.

However, most houshold electronics are rated for 100-240v, and grid power shows up as 110v. My novice understanding leads me to think that at such a lower voltgae, the Amp draw would be much higher and cause breakers to switch off.


texts:
I would like to know if I can replace a safety Y2 capacitor (222m 300V - which is a 2.2nf-)with a safety X2 capacitor temporarily.
I'm in a hurry and I already ordered the replacement part but while I'm waiting I would like to know what do I have in my hands to keep the device working. My device has 220V input and 12V5A output.
I read here that :

A Y2 capacitor can safely be used in place of an X2 capacitor, but an
X2 capacitor should not be used in place of a Y2 capacitor. This is
because, although an X2-type capacitor would work and filter noise
sufficiently, it would not meet the line-to-ground safety standards.
Y2 safety capacitors are more robust, are able to withstand higher
peak impulse voltages, and are designed to fail open as opposed to
failing short

But as I said it's for a very short period of time (like a 3 weeks or so)
Or maybe another idea ? Classic 1KV ceramic capacitor maybe can do the work ?
Thanks
EDIT :
The problem seems to be somwhere else I will open a new topic. Thanks !


texts: BJTs versus (MOS)FET to switch a load from a microcontroller

texts:
I would like to know what are the reasons for choosing bipolar junction transistor (BJT) versus a field-effect transistor (FET) (MOSFET or a JFET) to switch a load from a microcontroller. In our hypothetical situation, assume that the load requires more current than the microcontroller can provide, and the question is what considerations would bias in favor or against the BJT and a FET switch design, assuming that "ease of use" is not a consideration.

This question is a more specific version of the  when to use what transistor question.


texts:
After checking multiple suppliers and reading about HW secure elements, I would like to understand the use of this type of electronic components.

Maybe I´m wrong, but it seems a HW secure element provides a Root of Trust for a certain data. This is, the HW Secure Element assures that, for example, a private key, will only be known by the secure element itself. Is this correct?

Now, thinking about a system where a SoC generates automatically a private key and stores it in a Trust Zone, wouldn´t this be similar to a HW secure element?

Is there an alternative to HW Secure Element in a SoC?


texts: how to change 12V in to multi out (9v, 5v, 12v)

texts: I'm hoping this is the kind of thing we can just buy rather than build, but open to building. We need to take a 12V DC in from a marine battery and power a Raspberry Pi (5v), camera (9v) and AES receiver (12v). Can anyone tell me what the smart way to do this would be? I don't know enough to know if I should be looking at buck converters or linear regulators, pointers welcome.


texts: What component provides the bulk of the current in a buck converter? the capacitor or the inductor?

texts:
I’m studying buck converters and I have found contradicting sources claiming either of these statements:

The inductor stores and releases the bulk of the current, the capacitor is there just for smoothing its output in an auxiliary role.
The capacitor stores and releases the bulk of the current, the inductor is there in an auxiliary role to slow down the capacitor's charge time so that there is no huge current spike when it's charging up at the start of each  cycle.

I'm confused, I did a simulation and I seem to be able to omit either the capacitor or the inductor and I'm still getting a decent output, this only deepens my confusion.

Which component is supposed to provide the bulk of the current to the load and which component is supposed to perform an auxiliary role? And why is it not the other way around?
EDIT: This link provides aditional explaination about why an RC filter is not a great power source and elaborates on the reason why the inductor is the main current provider.


texts:
I need to generate a negative voltage of approximately -12V from a 12V power supply. I read about ICL7660A that performs supply voltage conversions from positive to negative for  an input range of +1.5V to +12.0V resulting in complementary output voltages of -1.5V to -12.0V. I need it to feed NE5532 OPAMPs symmetrically to perform a low pass filter, to transform a square wave into a sine wave.

However, I looked at the ICL7660A datasheet and it does not explain very much about current capacity, just a graph (datasheet Figure 7) of load current vs. output voltage. In that graph, the ICL7660A is fed by a 5V power supply and the load current seems to reach zero when output voltage reaches -5V.

(Image source: Figure 7 from ICL7660A datasheet)

I don't know exactly how much current will be required, but there are 4 NE5532 OPAMPs. I suppose that something near 50 mA is enough, no more than that.

So, I was thinking: I need -12V from a 12V power supply, is it possible? If not, is there a better approach?


texts:
My aim is to keep temperature constant at a certain place. I don't have a mathematical model of the plant.

Currently, PID is used with some fixed Kp, Ki, and Kd, and I want to optimize these parameters for a stable system. PID is giving output to a non-linear control valve which is used to control a temperature by changing the flow of water.

The error input to the PID controller, control valve opening, and actual output temperature are available to me. For example, setpoint of 980 °C, actual output 998 °C, error -18 °C, valve opening 33%.   I have many data points like this available to me.

I am confused what is my system here, the control valve which is injecting water for the corresponding PID input or the place where I want to keep the temperature constant?

Is it possible to tune the PID from the following data and get the plant model?


texts:
Antenna

Guys I am planning on a using the linked antenna on an arduino proto board with 868 data radio and bluetooth chip. I just want to confirm, is it as simple as following the recommended layout and ground plane of the antenna and feeding the same antenna with the two different RF chips in alternative times. is an RF switch or special circuitry required ? any suggestions is welcome

thank you


texts: I've connected my SIM900a module with PC via a USB to TTL converter. I'm using Proteus Virtual Terminal for check the AT commands. The problem is I can't type anything on the Virtual Terminal. Copy Paste option also not working. What can I do?


texts: mc1322x on Contiki-os, development environment

texts:
I want to ask if there is ready to run Virtual Machine image anyone to develop on mc1322x microchip on Contiki-os.

Why I ask is this, I'm dealing with this for 3 weeks, and what I advance to take is nothing.

Is there anyone who is experienced in contiki-os - mc1322x agreement?


texts: Power supply design - what safety mechanisms are needed?

texts:
When evaluating or designing a power supply for instrumentation (let's say a CT scanner b/c that's my field, and the environment is always changing), what safety mechanisms should I verify?
What I can think of is

Transient input suppression
Load short circuit handling
Component thermal limits
Arcing / voltage tracking between traces

I'm considering a switched mode buck supply, possibly isolated.
What are other considerations to ensure the supply doesn't damage other components, it doesn't smoke, and that no one gets electrocuted?
Is there a standard that, if I follow, the design is considered safe?
Personally, I find this field quite different from civil engineering, where there are lists of mandated calculations you must do for a particular project.


texts: Is my schematics correct? (Atmega328p for solenoids control)

texts:
Finally I finished the second version of my circuit which should control different solenoids.

You can view the large version here.

In particular, this circuit should control 2 proportional solenoids and 7 ON/OFF solenoids.

The solenoids parameters are:
V = 12Vcc, R = 3.7 Ohm, I = 1.80A

In order to prevent an atmega328p reset due to noise (like it happened in the first version), I added:

an optoisolator 6N136 for each output,
a MOSFET driver MCP1406 for each MOSFET
an isolated power supply THL-25 to power up the atmega328p (main battery is an AGM Battery 12V, 200Ah).

As suggested in the application note of its datasheet, I used an inductor L1-1UH with a capacitor for the THL-25 input. Is it OK?

In this way, I have two different grounds, GND5 is the gnd for 12V, while GND is the ground for 5V . I also added a big 2200uF capacitor between +12V and GND5 in order to avoid noise.
The capacitor C5 100nF is OK for the atmega328p?
I will place it very close to the atmega pins.

The output named "OUT5/SERVO PWM" should control a 12V, 4A RC servo.

Is there any error in my schematics?

Anything to improve?

The big C3 capacitor is enough for the filtering?

The circuit close to the isolated power supply is correct?

Can you help me, please?

I would like to improve my circuit, if possible.

Thank you for your support and your help!

EDIT1: I updated my schematics by adding the SERVO connections and pinout.
EDIT2: I changed the SERVO circuit by using a P-mosfet. This is the SERVO schematics.

EDIT3:: This is the new schematics for the servo controlling.


texts: Companion capacitor model in circuit simulation

texts:
Im looking for a very simple example of an algorithm using the capacitor companion model. I have searched online in several different combinations to try to find an example but cant find one that gives me all of the information I need.

I just need to see how to model an RC circuit with a dc voltage input. I have found the equations but I need to see an example of how to implement it, I am trying to implement it in matlab.

Equations I have so far are:

Req = DeltaT/2C or DeltaT/C

Ieq = -2CVo/deltaT - Io

Again I keep finding these equations and terms like "Trapezoidal method" and "Eulers Method" but I cannot find anywhere a simple easy to follow example of how to actually use these equations.

I understand that the equations are using previous terms to calculate the next term but again I cant find example where the problem is worked out.

I understand I could by spice simulation books but this is really just a specific question, I dont want to buy a 50$ book just to find out how to do this one thing.

simulate this circuit – Schematic created using CircuitLab

Also I am assuming that at T = 0, the voltage across the capacitor is O.


texts: Why use a buffer in/output for a RAM memory?

texts: I was reading about the architeture of a RAM memory but now I'm confused about the use of buffer for input and output. Why I need to use this?


texts: How to detect the Accelerometer is moving

texts:
I am using the MCU intergrade 3-axis accelerometer and set it on the bicycle.
I want to detect the bicycle is moving or stop.
But the vibration noise let my function failed.

Is anyone could share some information about accelerometer detect moving.

Thank you.


texts:
I am a Computer Science student so this is not quite my area of knowledge but I have tried to find as much information as I could.
I am creating a project using an Arduino and an electromagnetic door lock.
I know that the Arduino can output either 3.3V 0.8A DC or 5V 0.8A DC which means the coil of the relay must be able to activate with one of these.
The electromagnetic door lock runs on 12v 110mA DC so I know that the output side has to support that from the common.
Also for what I am doing I know that I need an SPDT relay so that I can use a No and NC line.
What numbers do I need to need to look at on the relay to know if it can run using what I have.
This is one that i have found and I don't know if it would work:
https://uk.banggood.com/3Pcs-5V-Relay-5-12V-TTL-Signal-1-Channel-Module-High-Level-Expansion-Board-p-1178211.html?rmmds=search&cur_warehouse=CN
Any help would be much appreciated,
Thanks


texts: What's the difference between similarly rated DC motors with different nominal voltages?

texts: I'm looking at a datasheet that describes several versions of the "same" DC motor. The versions are mostly similar (e.g. same size, no-load speed...) except for the nominal voltage, no-load current and nominal torque. What's the internal differences between these versions (your guess)? and what are the pros and cons of choosing one over the other?


texts: Driving a brushless DC motor (with a UC3625?)

texts:
I am trying to drive a brushless DC motor with hall effect sensors using a microcontroller and a TI UC3625 controller.

Thing is, I haven't had much luck. Its a beast of a chip and I've tried wiring it like the "typical application" in the datasheet, I've looked at all the product notes I can find on google, etc.  It seems like the suggested (possibly only?) way to drive it is by sending it a voltage.

Is this normal for a BLDC controller?  I would think the standard would be PWM input.  Can anyone recommend a way to get this thing working or suggest a different chip for driving a BLDC with hall effect sensors (and about 3A at 22V)?


texts:
From the given diagram:

Conductor(C) is the only movable part with given velocity (v), connected to a stationary terminals(top & bottom) and an exterior circuit with a load.

Will current flow to the load? Or only around the conductor? Is the voltage equal to motional EMF:

$$ \epsilon = vBL$$
Or it the voltage much less now because most of the conductor is not inside the magnetic field region?
If I we're to pick any point on the top&bottom terminals with a volt meter, would the voltage at any point be vBL?

How is the resistance inside the magnetic field, and the resistance outside the magnetic field change things? Or should they all be R(sum of both resistances)?


texts: Connecting latch to ram via 8 horizontal tracks within IC (auto-routed style)

texts:
Here's the issue with eagle autorouter and me trying to connect a 62256 ram chip to a 74HC574 latch (even with clock and latch enable disconnected)

I measured the width in the trouble IC (74HC574) and its 6 mm. I went paranoid and decided to allow eagle to use 0.1mm track width and 0.1mm track spacing. I used 0.3mm spacing between pad and anything else next to it. I set the restring (of the pads) to 0.24mm and to make the pads small and circular instead of oval, I set Elongation to 0 instead of 100.

In the miscellaneous section, I unchecked "check grid", "check angle", "check font" and "check restrict".

I think I did very good so far.

So here's my math if I used 0.1mm track width and 0.1mm track space:

 0.3mm initial spacing from end of pad = 0.3mm
+0.1mm 1st track width = 0.4mm
+0.1mm 1st space = 0.5mm
+0.1mm 2nd track width = 0.6mm
+0.1mm 2nd space = 0.7mm
+0.1mm 3rd track width = 0.8mm
+0.1mm 3rd space = 0.9mm
+0.1mm 4th track width = 1mm
+0.1mm 4th space = 1.1mm
+0.1mm 5th track width = 1.2mm
+0.1mm 5th space = 1.3mm
+0.1mm 6th track width = 1.4mm
+0.1mm 6th space = 1.5mm
+0.1mm 7th track width = 1.6mm
+0.1mm 7th space = 1.7mm
+0.1mm 7th track width = 1.8mm
+0.1mm 7th space = 1.9mm
+0.1mm 8th track width = 2mm
+0.3mm space to next pad = 2.3mm

and even if I doubled the track width, I'd still have space.

I also tried changing all cost settings under the Route tab in autorouter to "0" except I left the polygon setting alone and I even set the autorouting grid to 0.2mm.

Here's part of the pcb completely unrouted

Here's how I hand-routed the board but it took me 10 minutes and I don't want to spend 10 minutes per complete routing attempt.

This is how eagle routes it:

It didn't finish.

In every auto-routing attempt I made, there was not one time that eagle would start a track horizontally from an IC pin (such as what I did with my ground pin of the 74HC574), and this is even after I set the preferred track direction to horizontal.

How do I configure eagle to auto-route these tracks properly (or at least how do I configure eagle to make tracks run horizontally out of the ground and VCC pins of digital IC's)?


texts: How to determine Vth, Kn and delta from NMOS datasheet

texts:
Given this two graphs below, how do I determine Vth, Kn and delta from this?

I used this formula's so far:

The graphs are taken from the datasheet of Supertex VN10K

Can someone please help me in the right direction?

(1) I used two Id(non-sat) equations to determine Vtn as 2.5V. When replacing this into one of the two equations I get 0*Kn = Id(non-sat)... That's impossible, right? Isn't Vtn a constant value for the mosfet?

(2) When replacing it into a new Id(non-sat) equation I get 115mA/V^2... When I substitue Kn and Vtn into a Id(sat) equation I get delta as a negative value...

Am I doing anything wrong? Is it possible for delta to have a negative value?

Thanks!


texts:
So, I'm a High school student, and for engineering, our project requires chargine a semi-large array of UPS batteries. The batteries need to output 36v and 4.5A max, and I plan on getting a transformer capable of putting out enough power to charge them.

What my issue is, is finding a way to disconnect the battery bank from the transformer when they are charged.

I have asked my father, who has forgotten more than I know, and he's said that there were likely IC's out there to do what I need. I found this IC, which is kinda similar to what I need to do, but this thing can't handle anywhere near the wattage I need.

Is there an IC to do what I need, or will I need to design my own? If I have to design my own, how would I go about doing it. What components would I need to use, and what are their functions. I want to understand why they're doing what they do.

TL;DR: Need a 36v 4.5A lead acid smart charger, and want to understand how it works.


texts: Microwave Oscillator: Both Ports Unstable?

texts:
I'm just wondering, for  microwave oscillators, I think both ports need to be in the transistor's unstable region.  What would happen if just one port were in the unstable region and the other in the stable region?  Could it oscillate? I'm thinking maybe it'd try to oscillate at one port, and the other port would attenuate the oscillation and the circuit would probably just do nothing.

Update:

The image below is from RF Circuit Design: Theory and Applications by R. Ludwig and P. Bretchko.

Basically, what I'm asking is, what happens if \$\Gamma_{S}\$ is chosen such that it lies in the transistor's unstable region, whereas \$\Gamma_{L}\$ is chosen such that it lies in the transistor's stable region.  My understanding is that both \$\Gamma_{S}\$ and \$\Gamma_{L}\$ must be in the transistor's unstable region for this to be an oscillator.


texts:
I've seen power protection that uses:

MOV (metal-oxide varistor)
Inductor
TVS diode

  Application Note: Transient Voltage Suppressors  (TVS Diode)
  Applications Overview

I didn't see any design guide for the inductor selection I choose 1 A inductor 4.7 µH, but doesn't that mean it will carry the surge current  that TVS should clamp?

I'm not sure is 4.7 µH the right selection or not.


texts: Voltage regulator outputs some voltage even if in shutdown

texts:
I've created a dual source energy harvesting board to store energy from small energy sources, like a 3V 15mA solar panel, into a 3F 2.7V supercap and to power a small wireless node (3.3V, 30mA), but I am having trouble finding the cause of a current leak.

Schematic is below:

The voltage regulator LTC3125 (U1) gets the energy from the solar panel and steps the voltage up to 2.65V to charge the 3F 2.7V supercap.

The supercap is the input for the 3.3V voltage stepup regulator LTC3525D-3.3 (U3) and its output (3.3V) goes to the load (wireless node).

This regulator get shut down when the voltage of the supercap goes below 1.1V and starts if the supercap goes above 2.3V. This is done by the non-inverting op-amp with additional hystheresis, the MAX9015 (U2), that drives the shutdown pin of the LTC3525.

The op-amp is powered by two sources: if the sun shines, it is powered by the 2.1V regulated voltage from the LTC3105 (LDO, pin2). If no sun and supercap >1.1V, the power comes from the LTC3525D-3.3 output. If no sun and supercap <=1.1, then the opamp is off and so is the LTC3525. Usually the supercap is >1.1V.

My problem is the following.

I let the supercap discharge thanks to a 1k resistor load on the 3.3V output of LTC3525.

At 1.1V the op-amp drives the SHDN pin of LTC325 low (0.00V) and the latter goes off (0.00V output) and the current draw from the supercap is about 10uA.
With a power supply I simulate a solar panel and charge the supercap with 30mA@3V.

After a few seconds I turn off the power supply, the supercap stops charging, the current draw from it is 10uA for 1 second, then suddenly it goes to 2.3mA (1k res as load) and the output of LTC3525 is about 0.4V if supercap @1.4V or 1V if supercap @ 1.8V.

On the SHDN pin of LTC3525 I measure max 0.2V (polling every 5ms), average 0.04V. the LTC3525 shuts down if SHDN <0.4V and start if >1V.
I added the pulldown resistor with a low value (20K) on the op-amp output, so that it does not float.

The current leak stays there until the supercap goes to about 1.2V.
If I turn on the power supply a few secs and shut it down, the problem repeats.

If I leave the board off a few hours and without the supercap, then turn of the power supply just a couple of secs, there is no current leak. If I leave the psu on for 10 more secs, current leak starts again.

Holding with ceramic tweezers a resistor in parallel with R8 (pull-down on op-amp output) but going to on other GND pin (supercap GND), while the leak is happendin, it stops it. If I connect  that resistor before the current leak starts, it doesn't solve the problem.

Maybe the output of the op-amp is floating really fast, that I don't see it with the multimeter and it is turning off and on the LTC3525 very quickly?
If so, how do I prevent the floating, if there is no power source anywhere in the circuit?

Or maybe the cause is something else?

Thanks for your help

Sincerely


texts: What's the concept of these three options for configuring the memory of STM32?

texts:
I have read the STM32F10x Reference manual but a section about "Reading the Flash memory" is not clear to me, yet. I mean this part(page 59):

I have several question:

What's the Latency? in fact I cannot underestand this part "read operation programmed on-the-fly". especially "on-the-fly"!? is it a concept? Why should I configure the Latency? What will happen if I don't configure it?
Is it a type of cache? What's the usage it?
Half cycle! ok, that's clear but I want to know how it can save the power when we disable of enable it?


texts: how to drive a N channel Mosfet transistor

texts:
Hi
I'm using an atmega 16 chip to drive a BS170 N channel enhancement mosfet. I'm unsure how would I go about this. Having read the datasheet, I'm guessing  I set the pin the fet is connected to as a output pin. I would then set the PORTxn to high for on and low for off. Yes?

I would have eight of these connected to the same chip. Is that ok?


texts: How do you work out ripple current for a Power supply design

texts: I hear the ripple current rating of a cap is important because caps have internal resistence which can cause over heating of capacitors. I was wondering is there any general rules a professional engineer would follow when designing a linear supply?


texts: SMPS output voltage too low - what to look for?

texts:
I have an old switching power supply for HP 712/60 workstation (+5V, +3V3, +12v). It was working about ten years ago when i've last tried to boot the system, but now one of the output voltages is at half of the nominal value (12V output is at 5.6V). I have replaced all of the electrolytic capacitors in the SMPS, and resoldered all points on low voltage section - still 12V output is at 5.6V. What to look for next?
General question - SMPS has output voltage lower than nominal - what troubleshooting strategy should i take to find the culprit?


texts: Components for a WiFi enabled IR controller

texts: I don't have any experience with electronics really but I do have experience in programming.  I'm interested in writing a program to control my stereo, TV etc.  To achieve this I'll need a piece of hardware which is WiFi capable and can generate a range of infrared signals to control my TV, stereo and other infrared capable devices.  Given my lack of experience with microcontrollers etc, I'd probably find it easier if I could minimize the amount of work the hardware had to do and focussed it on converting data it receives via WiFi into infrared.  What components would I require and are there any relatively inexpensive out-of-the-box solutions which will have the majority of what I need without requiring too much additional soldering?  Also, at a high level, what way should the operation of such a device be architected?


texts: How does a bathroom scale automatically power on when I step on it?

texts: When I step on a bathroom scale how does the circuit turn on? I've disassembled these types of weight scales looking for obvious hardware switches, but none exist. I suspect the ADC is configured to generate an interrupt and wake the micro controller from a low power mode. If this is the case, how would this spec be translated to a common micro controller such as a MSP430F67 with its built-in 24-bit ADCs?


texts:
I used name tool.

I clicked #7 for the left and named CS and then i clicked #3 for the right and named CS

They should be the same after the connect each other question . However the gray are like in this picture didn't occur.

Did i do right? if yes, how do i see our connected pins if they are connected?


texts: Unbalanced RF output to FEM module with balanced input

texts:
I have a working ZigBee system based on ATMEGA256RFR2.
(Datasheet)
On page 33 you can check the RF system of this IC.

Now I want to use a FEM module to increase the performance and I found the SKYWorks SKY66114-11 which is designed for this exact purpose. (Datasheet)

On the ATMEL chip there is a balanced output of RFP and RFN which normally would go into a Balun and then to the final antenna.

However I could not find any documentation on how to connect those unbalance RF pins of ATMEL to the SKY IC's standalone pin.

I'm not sure if I would need the balun or not and what would be the recommended matching circuit.

Looking at an Atmel Application Note (AN42140):
They are connecting an RCB256RFR2 board (Datasheet) to an SE2431L (Datasheet).
There are only one balun between the two of them. No resistors, no capacitors.
Is it okay? Connecting them together without any matching circuit?

What do you think?


texts:
I am in the process of selecting a suitable FET to switch a resistive load (LEDs), triggered by a 3.3v MCU signal. The schematic would be:

However, I am having some trouble with my (rough) calculations for the CSD16342Q5A. From the datasheet -
\$R_{DS(on)}\$ = 6.1mΩ
\$R_{\theta JA}\$ = 123 °C/W (Pg 3 - taking into account that I would be not using additional copper for a head sink )

The rise in temperature as a function of the drain current \$I_D\$ is plotted as:

The questions

How does one factoring in the effect of the PWM switching. Should
one use Figure 1. of the datasheet to factor in those effects?
How would one determine the gate current that the MCU has to sink/source for each toggle?
How does one proceed if \$R_{DS}\$ values at the \$V_{GS}\$ = 3.3v aren't available (but \$V_{GS(threshold)}\$ is 1.8v) and only given for \$V_{GS}\$ = 4.5v (eg.CSD18536KT)


texts: timelines of IC manufacturer company acquisitions/renames/spinoffs/etc.?

texts:
I'm wondering if there's any place out there on the 'Net that compiles information about semiconductor company acquisitions/renames/spinoffs/etc.

Just in the last 10 years, TI acquired National, Diodes Inc acquired Zetex, Maxim acquired Dallas Semiconductor, Agilent spun off Avago, and Tyco changed its name to TE.

(is this directly relevant to practical circuit design? no, but it has indirect usefulness for understanding history, esp. if you find old chip logos or datasheets.)


texts: How is pipelined DES different from sequential DES?

texts:
I implemented DES (Data Encryption Standard) Coder in VHDL using ISE IDE by Xilinx in sequential architecture which was pretty easy and straightforward. Now my task is to do the same using pipelined architecture so that the whole thing will work with maximum possible clock frequency. I read numerous papers from IEEE site concerning pipelined DES but still I couldn't fully get my head around the topic. What is different? So far I understood that I have to make it so:

There are no complex instructions in the code of every module. For example if I had instruction "x <= a * b * c" I'd have to break it down to two instructions in for loop and when iterator is equal to 0 do "temp <= a * b" and when iterator is equal 1 do "x <= temp * c". Just an example but shows the way of thinking - instead of one complex instructions - many simple ones (using loops or for generate).

Once input A gets to Feistel Round 2 then input B (for example next 64-bit plaintext word) gets loaded immediately to Feistel Round 1 and so on allowing us to process 16 words "quasi simultaneously". That would require us to have a synchronizing register before and after every Feistel Function module. Also I read something about modules for "pipeline" and "control module" although none of the articles mentioned how they worked. To be honest I have zero ideas about how to implement this part.

Are my presumptions wrong at any of the 2 points? Could anyone please explain to me in detail how to bite into this problem? Does anyone have an example of working pipelined DES Coder/Decoder on FPGA? I will be thankful for every bit of help.


texts: What is the advantage of a Sallen-Key filter over a normal second order filter?

texts:
Wikipedia links to a Sallen-Key filter as a active low pass, so I tried it out with LTSpice.

The frequency response and phase response are not linear, instead frequency response even gets higher after 10kHz. Why is that, and why would I use a Sallen-Key filter instead of a "normal" low pass filter?

The Sallen-Key is on the blue line.


texts:
I need to generate 20,000 lux of light in an indoor environment. I am having trouble converting the lumens to lux using online converters ( I know there are many such converters but the questions they ask are ambiguous).

Here is my situation:

I will have 25 light bulbs in a straight line above my head. Each light bulb will emit 800 lumens of light. The light bulbs will be 3 ft above my head. They will span around 5 feet in length. In other words, some light bulbs will be directly above my head, some will be a little to the right and others will be a little to the left.

How can I calculate the amount of lux that will hit my eyes?

What makes things further complex is that the light is radiating from all sides of the bulb (I'm talking about standard bulbs) so it is difficult to know how much light will radiate downward (in my direction)..

Thanks in advance for any advice.


texts: What are the advantages of DSB AM with carrier?

texts:
I saw an exam question that asked what the advantages of using DSB AM with carrier are. I can't find anything conclusive in my books or by googling.

It seems to me that DSB AM with carrier is less power-efficient (compared to DSB-SC ΑΜ and SSB AM) and that it carries redundant information (compared to SSB AM). The only thing I could interpret as an advantage is perhaps simplicity of demodulation.

So am I missing anything? What are the actual advantages of using DSB AM with carrier?


texts:
I've looked at similar threads on stackechange but none seem to provide an answer.

I have 2 devices running on 12v DC. One at 1A and the other at 2A.

I had an existing 12V 7Ah lead acid battery with a 0.8A charger.
My thinking was to connect the charger to battery, then connect both devices to the battery as well and when power is lost the 2 devices will continue operating.

This failed miserably and the charger wasn't able to provide the 3A required constantly by the devices.

My question is: how would I go about powering the 2 units (12V 3Ah) from AC while there is AC and when AC is lost automatically use the battery power?

I don't mind getting my hands dirty and constructing the circuit, I just have no idea where to begin.

Thanks!
Amir


texts: could you please tell me how to determine where the gate-source-voltage would be in this image for both a n-mos and p-mos.


texts:
I was working on the SPI protocol and have some few questions regarding the SPI clock. I know that master always initiates the clock to start the communication.

Does the slave use this SPI clock generated by master or does it synchronize its own SPI clock with the SPI clock generated by master for further transmission and reception of data?

The slave can be a chip or a microcontroller.


texts:
I want to proof Quality Factor of 2nd order system is  \$ \frac{1}{2 \times \zeta} \$ ;
that is
 $$if \quad H(s)= \frac{k \times \omega_n^2}{s^2 + 2 \times \zeta \times \omega_n \times s + \omega_n^2} \quad
then \quad Q= \frac{1}{2 \times \zeta} $$

My Approach:

Now how can i proceed?


texts: How exactly does CPU set C/BE lines on a PCI bus?

texts:
In the PCI bus spec, when in the address phase of a transaction, there are extra bits for specifying the type of transaction (called C/BE). These lines are also re-used during the data phase of the transaction as byte enables.

My question is this: what is the exact series of steps for a CPU to set these bits?

Is there some memory-mapped controller on the motherboard with a register for the Address/Data pins, and a register for the C/BE pins? If so, does that mean every transaction on the PCI bus requires two writes from the CPU (one to set the address/data, another to set the C/BE pins)?


texts: Flyback transformer for hight ratio, low power, DC-DC step-up converter

texts:
I have to build a converter to get 300v from a 3.6v battery. Besides the hight conversion ratio it needs to be as small as posible.

I am planning to use a swticher IC like LMR64010 or similar configured as Flyback because, as far as I know, it is the best mode for low power & high ratio conversión.
As flyback transformer I am planning to use the small ATB322515-0110 but I am worried because, unlike other flyback transformers, it has no special indication to be used in pulse flyback mode. I am not sure if a transformer should meet any special requirement to be used that way.


texts: Measuring DC Load on Positive Ground 48vdc Telecom Power Plant

texts: I wish to measure dc load on negative conductor on a 48 volt positive ground telecom power plant. Which way should arrow on clamp be pointing? Would it be safe to say the correct current load would be the direction in which current measures highest?


texts: 1GHz digital oscilloscope with 50MS/s sample rate

texts:
Can someone please explain to me why can't I measure  a non-periodic pulse signal \$T_r=1ns\$, with a digital oscilloscope \$1GHz\$ with a sample rate of \$50MS/s\$?

I may have to solve similar problems in an entrance exam for Faculty of Electrical Engineering, so I would like to really understand the problem and the calculations.

Any help or hints are welcomed and appreciated. Thank you.