texts: (PSPICE) Memristor-Based IF Neuron Circuit: What is this NMOS?

texts:
This is a memristor-based IF neuron circuit.
My question is, i'm trying to simulate this circuit in PSPICE. However, I am unsure what the N-MOSFET characteristics (M1) are in the circuit diagram. I do not see any parameters in the paper. Do I just choose an arbitrary N-Mosfet from the mosfet library in PSPICE? What about it's Pspice model characteristics (vdd, bias current, etc)?

I don't see any characteristics about the MOSFET in the paper...unless i'm just missing it.

Paper Link: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6331427&tag=1


texts:
The task says:

  Determine the positive maximum power p (t), for the load connected to
  the voltage 230 V. The power consumption was 1350 W and the power
  factor was 0.85.

People have put this on hold because they said I did not try to solve it myself, I did but I did not write what I was doing because It led me to the wrong answer.

So I am gonna try again:
P = 1350 W

I know that power is a sine function so my initial thought is that giving me voltage and power factor is nothing more than trying to trick me.

I tried to solve it like this:

I know that \$p(t) = P\sqrt2sin(wt+φ)\$ so positive maximum should be \$P\sqrt2\$ which gives me 1909 but that answer is wrong.

after that I tried to find apparent power \$ S = \frac{1350}{0.85} = 1588\$ and multiply that with \$\sqrt2\$ and that would give me 2246 VA. (But that is also incorrect). The correct solution is 2938 W, and don't know why is that solution and not what i firstly tried

Any help is greatly appreciated


texts: Can I split one RS232 output signal into two signals?

texts:
I have one controller which processes data from a weigh scale. With it I can capture data using hyper terminal on a PC (RS232 communication - standard DB9 connector). Now I want to analyze it on another PC as well.

Unfortunately, my controller has only one RS232 output. Can I tap another RS 232 from the existing signal cable (by stripping the cable, taking out parallel signals and all)?

Or I need to use any custom hardware or cable?

Ah well, that was my original question, and I did try using the circuit, the problem is I can receive data only on one terminal. The splitter is not working. Totally Clueless now. Any Ideas ???


texts:
I am a programmer who has never worked with electronics before. I am learning the concepts and hoping to build a quadcopter, with the control software entirely written by me. Motor control seems to be the most important part.

Is it true that the typical brushless DC motor and ESC (Electronic Speed Control) can only approximately control the speed?  That's because the ESC seems to have only a very approximate idea how fast the motor is revolving. This still works for a PID (Proportional Integral Derivative) controller because it gets indirect feedback from say a gyroscope whether the motor is going fast enough and so it can tell the ESC to make it revolve "even faster" or "even slower", and that's good enough.

Is my understanding in the above paragraph correct?

If so, I wonder whether a servo motor that can inform about its current rate of rotation could help do away with the ESC entirely? I feel that if the microcontroller can receive an input about motor speeds and send an output requesting a certain speed, it would not need the ESC. But I am not sure how servo motors work -- what happens immediately after you request 100rpm when say they were at 80rpm?

Since they cannot adjust the immediately, should the microcontroller immediately adjust other motors to account for the fact that not all motors are at 100rpm yet?  Does that imply that the microcontroller should only request very small deltas from the currently measured speed, so that the period of deviation from desired state is negligible?

In the latter model, of requesting only very small deltas from currently measured speed, the algorithm seems like it would not really be PID since there is no way to control the acceleration? But may be requesting the servo to go from 80rpm to 100rpm causes it to reach 81rpm much faster than requesting it to go from 80rpm to 81rpm?

I feel I know so little I cannot put my finger on it more precisely, but I hope this gives an idea of the concepts I am struggling to absorb.

To summarize, the questions are:

can a servo (brushless dc) motor allow doing away with ESC?
does a servo motor accept control inputs such as "revolve at 100rpm"?
does a servo motor offer an output saying "i am at 80rpm now"?
does a servo motor at 80rpm go to 81rpm faster if it is requested to revolve at 100rpm versus at 81rpm?
the less precise questions implicit in the text above.


texts: Symmetrical Components - Three-phase D-Y transformer with unbalanced voltage and loads

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I have a Delta-Wye transformer, N1/N2 = 4, and am trying to solve the circuit below, with 120VAC applied to terminals VAB only. On the secondary I have 1 ohms connected between a-n and 5 ohms between b-n. The other parameters are:
rs = resistance of primary winding A, B, and C
rr = resistance of secondary winding a, b, and c
Llas = Primary leakage inductance on winding A
Llbs = Primary leakage inductance on winding B
Llcs = Primary leakage inductance on winding C
Llar = Secondary leakage inductance on winding a reflected to the primary
Llbr = Secondary leakage inductance on winding b reflected to the primary
Llcr = Secondary leakage inductance on winding c reflected to the primary
Lm = Mutual inductance
Does anyone know how to find the primary line current (IA) using the symmetrical components method? All examples that I could find use transformers balanced loaded. I really appreciate any help!


texts: I am conducting an experiment where I would like to heat up 18 AWG copper cables outdoors using to 50-60°C using 60 amps. The wires are wrapped with teflon to prevent damage to the cable.  Can I use a generic waterproof wire connectors (ex. Small Waterproof Wire Connectors, Aqua/Orange (20-Pack)) for my connections (link the image below) or do I need something special?


texts: Power Suppy for Modem Router from 12V Car battery

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How i can operate my modem router (KW58283 300M 11N ADSL2+ Modem Router) on 12V car battery.
The Modm router is rated as 12V ,1A.
I have this battery.
Force battey http://www.forcebatteries.com.pk/res/gallries/lgallery59536535.jpg

The complete router information are here:

  http://www.kasdanet.com/ENHCSZ/pro_view-20.html

can i connect it directly?


texts:
I'm building a big muff pi, here it is my schematic :

I also made the PCB with smd components, and all the connections seem to be correct.
I've plugged in the guitar but nothing happened, no sound at all.
So, since I don't have an oscilloscope I decided to measure some voltages across the PCB, just to see if I can figure out something (not a good idea I know). I noticed that the voltage across R21 is around 5V, and across C13 around 4V ( the board is powered by a 9V battery) so no voltage across J3 (potentiometer). It happens also across J1, no voltage at all.

Just to understand, Vab is equal to Vc13, as if C13 had a shortcut to gnd. I checked all the connections and they are correct.
This is the circuit that I have copied:

Any suggestions?

update:
Thank you all! I figured out that one connection beetwen a resistor and the base of a transistor was interrupted! The method that @Transistor suggested to me worked perfectly!


texts: configure tps25740 for only 5v in and out

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i am using the tps25740 from texas instruments to use a usb c port for charging a device( a laptop) and a power source for slave usb devices. since the other circuitry in the latop will not be able to handle more than 5 volts i need to configure the tps25740 to only use 5v power. from what i see, you have to leave the en9/12 pin floating. does leaving those pins floating stop the transmission of 9 or 12 (and above) volts period or just stop it initially?

all help is greatly appreciated,
vesper krate

http://www.ti.com/lit/ds/symlink/tps25740.pdf


texts: What are the drawbacks of transmitting RF frequencies through an antenna that is designed for different frequency?

texts: I've heard of a magic "resonant frequency" that antennas are designed for, what happens if you transmit a frequency through an antenna that does not have the same resonant frequency?


texts:
First post, and I hope I'm in the right place.

Long story short, I have some led strips that normally draw power from a car battery, or large AGM via battery clamps. Well, I'm tired of having to carry around large heavy batteries. For Christmas, the wife got me a Ravpower Portable battery pack (Ravpower Super-C Series 26800) that has 2 USB ports and a USB-C port. Spec on the USB-C output says it will do 15V/2A. The draw on my lights are 12V/2A. I could probably get away with 10.5v or 11v.

Anyway, I've been looking high and low for a way to go from USB-C to 12V. The only thing I've seen is a small adapter on eBay that converts C to a barrel jack but, I've read that it will only put out 5v because of the way USB-C "detects" the device it is hooked up to and adjusts the voltage accordingly. I think that if there isn't a cable or product that allows you to do so, developing one would be a great idea. Especially for someone like me who has so many uses for 12v (lights, mobile drone battery charging, cpap machine) but, doesn't want to be limited to large batteries or Portable chargers with the 12v barrel already in them.

So, if anyone has any ideas as to where to begin to look for a solution to my problem, it would be greatly appreciated. Thank you in advance.


texts: Where in AC the charge gets its energy again?

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I'm quite new to electronics. Most of the tutorials I've watched are DC oriented and it's pretty clear that there's a voltage drop across the DC circuit. When current flows through components in DC, there's a voltage drop across each component.

Can someone help me understand how does this work in AC? Let's say I have a AC circuit with just a light bulb.

There's a positive current flow
it goes through light bulb and loses some energy
then the flow reverses and goes the other way
the light bulb still lights up

I can't seem to understand how does the light bulb in step 4 still light up when the electrons lose their energy/charge after going through it?


texts: I've been trying to simulate the circuit above in time domain mode with pspice and i've used Sw_tClose/ANL-MISC to simulate a switch which gets closed at time t=0 , but the simulation as you can see shows different voltages at two sides of switch which i expected to be equal and further more when i plot the Capacitor voltage as you can see its starting from 1Volt instead of 0 Volt , can you help me and provide me with some information here , thank you


texts: In my book it says that the capacitance in a capacitor with n electrodes is (n-1)*Co, Co is a capacitance of a two parallel plates capacitor. I know how to distribute charge when there are 3 parallel plates( two of them are connected to single Q,and the third which is in the middle to -Q), and I get 2*Co, but I can't figure out how to distribute charge when there are four of them.


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I came across this section in the paper Providing quality of service over a shared wireless link, IEEE Communications Magazine:

  Consider a very simple system with two users. The service rate (in a time slot) for user 1 is either 76.8 kb/s or 153.6 kb/s with equal probabilities 0.5. For user 2 the rates are 153.6 kb/s or 307.2 kb/s, also with equal probabilities. (Thus, the channel quality of user 2 is better on average.) Assume that channels for both users are independent, and there is unlimited amount of data to transmit to each user. Then, a “naive” round-robin allocation of time slots to the users will result in users served at the average rates R1= 0.5 x(0.5 x 76.8 + 0.5 x 153.6)= 57.6 kb/s and R2= 0.5 x(0.5 x153.6 + 0.5 x307.2) = 115.2 kb/s, respectively. Consider another scheduling scheme where a user with a “relatively better” (in a current time slot) service rate (153.6 kb/s for user 1 and 307.2 kb/s for user 2) is scheduled. In case of a “tie” (i.e., if channels are relatively better or relatively worse for both users), the user to serve is chosen randomly with equal probabilities 0.5 . A straightforward calculation shows that with this scheduling, the average rates are R1 = 67.2 and R2 = 134.4 kb/s, which is 16 percent higher for each user than with the round-robin  discipline.  This  is  an  example  of proportionally fair scheduling.

I'm trying to figure out the rates (marked in bold) that have been obtained for the proportionally fair case. As per my understanding, user 1 would get selected over user 2 only 1/8th of the time (because with probability 0.5, user 1 sees a rate of 153.6 kb/s, which can get chosen over user 2 only 1/4th of the time since user 2 can see a rate of 153.6 with probabilty=0.5 and then user 1 is selected randomly with another probability of 0.5). Then, R1 = (1/8)x(0.5 x 76.8 + 0.5 x 153.6) =  14.4 kbps and R2 = (7/8)x(0.5 x153.6 + 0.5 x307.2) = 201.6 kbps.

What am I missing here? This seems to be a simple math problem, but I think I've not understood the concept of proportional fairness correctly.


texts:
I am trying to drive two piezo inkjet print heads with an analog waveform varying from 0-40V, with a slew rate of 15V/us and a complicated waveform of a duration of ~20us. When printing only one nozzle will print at a time but the nozzles will fire in sequence.

I have considered the following circuit (displaying only 3 outputs), an FPGA linked to a DAC will generate the waveform, this will be connected to all 32 nozzles. Firing of a nozzle is carried out by using a transistor (Accidentally picture Darlington) switch also connected to the FPGA.

I believe this circuit although crude would be capable in firing any nozzle with the complex analog waveform, the issue I have is that I would like  a different waveform applied to every nozzle not currently jetting.

For succesful jetting it is required that a constant voltage is applied to all nozzles so a voltage drop is possible during activation. It is imperative that there is no voltage spikes from switching between the "non-printing" and "printing" voltages.

I have considered using a second DAC to generate the constant voltage, that this second DAC is in series with the primary DAC and that a method for switching the second DAC on/off for each channel.


texts: prevent receiver components from interfering with output of modulator

texts:
I am working on an ASK modulator and de-modulator. The modulator works fine (thanks to great folks at SE). However when I try to pass the modulator output to the input terminal of the receiver, the output becomes 0 mostly due to the interference of components of receiver.

Below is the image showing simulation output when modulator is not connected to the receiver:

Green is the ASK output which looks good, red is the digital signal and blue is the carrier.

However when I connect the green output to the receiver (where antenna would be there in real scenario,) this output is generated:

Yellow is supposed to be demodulated output.

We can see that green is now 0. Please help me figure out a way so that I can test in simulation whether my demodulator is working or not.

EDIT-

As requested, pfb the circuit. It's built using multisim on a windows machine.


texts: How to derive the node voltage for this comparator with hysteresis?

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I have the following circuit. U26 is a simple unity buffer and U15 is just a dual comparator.

I want the top comparator to compare the battery voltage (VBAT/2) on the inverting input with 2.0V reference on the non-inverting input. I also want 50mV of hysteresis. For some reason, pin 3 is sitting at 2.8V and pin6 at 2.4V. I figure it has to do with the Req of R13, R14, and R16 but I can't seem to figure out how to get the equations to work to make pin three of U15 2.0V and have hysteresis.

Likewise, I want the bottom comparator to compare VBAT/2 with 1.70V on the inverting pin and have 50mV of hysteresis made with R22 and R23.

The equations and how to derive them to get pin 3 at 2.0V, pin 6 at 1.7V and 50mV of hysteresis for each comparator will be accepted.

The output is just 3 LEDs where only 1 can be on at once, being on when the output of the comparator is low.

EDIT:

So what I got working was to multiply R21, R22, and R23 by 10. This gives me the desired effect. I see no downsides to this method? I still can't derive the equation that figures out the voltages at pins 3 and 6 though.


texts: What ISA is used by Cortex-M/R/A and what compilers are available?

texts:
What ISA is used by Cortex-M/R/A?

What is the difference between arm-none-eabi and arm-elf-gcc?
Are there any other compilers for ARM devices worth mentioning?


texts: Getting different impulse responses by solving with Laplace transform and plugging delta-dirac

texts:
If I know that the output of a system $$y(t) = 2e^{-3t} \cdot u(t)$$
and it's specified that the input is $$ x(t) = u(t) $$

I was trying to find the impulse response h(t).

So I solved it using Laplace transform and I got the output $$ h(t) = 2\delta(t) - [6 e^{-3t} \cdot u(t)]$$
by doing the following:
$$ y(t) = x(t) * h(t) $$
therefore $$ Y(s) = X(s) \cdot H(s) $$
and by doing the laplace transform to y(t) and x(t) I optain:
$$ \frac{2}{s+3} = \frac{1}{s} \cdot H(s)$$
$$ H(s) = \frac{2s}{s + 3}$$
$$ H(s) = \frac{2(s + 3) - 6}{s + 3}$$
$$ H(s) = 2 + \frac {-6}{s + 3}$$

therefore, by using the inverse Laplace transform, I got:
$$ h(t) = 2\delta(t) - [6e^{-3t} \cdot u(t)] $$

Until now I think I understand it. From now on, I'd like you to correct me if I'm wrong at anything.

I know that h(t), the impulse response is the output if the input is the impulse function delta.

so I did the following:
I substituted x(t) in place of u(t) in the output equation, as x(t) = u(t)
$$ y(t) = 2e^{-3t} \cdot x(t) $$
and then I applied delta as the input to get the impulse response.

$$ h(t) = 2e^{-3t} \cdot \delta(t)$$
which can be reduced to
$$ h(t) = 2\delta(t) $$

I don't know what I've done wrong in that process to obtain a wrong answer in the second way.

Also, I'm pretty sure that the first impulse response is the right one because I've solved it in another way and obtained the same result (getting the step response and then differentiating it to obtain the impulse response.). It just didn't work out when I try to plug in delta.

Also, I apologize if the tags are not very accurate, but I just don't know how to categorize the question.


texts: selective photodiode transimpedance amplifier

texts:
i would like measure a tiny bit off reflected light from a modulated led in an ambient light environment.
I'm afraid the large ambient light output wil saturate my amplifier with the high amplification i need for the modulated led output.

Is there such a thing as a selective photodiode amplifier ? So only the light at the led carrier frequency gets amplified ?


texts:
Interesting (maybe?) question here which I am struggling to answer.  Hoping someone can help.

I have a capacitor network; 5 caps in parallel and then two modules of that configuration connected in series.  I am measuring the voltage of the bottom 5 caps using an Arduino Nano.  The Arduino and cap network are only linked by the cap negative (gnd) connected to the Arduino GND pin.  A bit crude but means I can measure negative voltages (i.e. 0V registers as 3V3 on the Nano):

I charged the circuit up for just shy of 24hrs to 2V4 from V+ to V-.  I checked the voltages across each of the caps and they were reasonably balanced (couple of hundred mV at most).  I.e. each cap is sat at 1V2, no current into or out of the system (bar a few uA due to cap internal leakage).

Now, I disconnect the V+ power supply (S1 goes to posn 3) and connect a load (to posn 1 of S2).  As expected, the network discharges into the load, favouring discharging the caps with lower value series resistors.  I.e. C1 & C6 discharge fastest, C5 & C10 slowest.

At ~75min I set the stack to open circuit.

At ~140min I re-apply the load.

The observation/question.  When the caps with fast RC constants (C1 & C6) reach 0V across the cap, they are fully discharged.  However, they then get pushed negative.  I.e. when measuring across the cap, a negative voltage appears.  It goes up to negative a few hundred mV.  Why? [Note: I have subtracted 3V3 from the voltage readings to get the correct reference with respect to the stack, not the Arduino].

I've scratched my head over this for a while and cannot understand what is driving the negative voltage across that cap, while the others in parallel remain positive.

I've deliberately been vague on the precise readings because the input impedance of my multimeter, and the Nano suck.  (I am in progress making a little voltage follower to solve this issue, and, also use a potentiostat rather than an Arduino!)  Apologies on this front.

Interestingly, I have modelled this circuit in Matlab and it predicted this.  I was somewhat hoping my model was wrong...maybe not?

Many thanks in advance,

Simon

PS:  Massive thanks and credit will be given to anyone able to help if they're happy me crediting them on a research paper.  If not, happy to not credit (I know some people don't like to be).
PPS: I've not gone into detail about what the circuit represents.  Happy to elaborate if people are interested (it's a skew-gaussian distribution BTW).


texts: Custom switched-mode power supply or UBEC?

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I'm in the process of designing a small, 5x5cm ATmega1284P-based microcontroller board. I would like it to regulate 6-18v input to 5v output, with a max continuous current rating of 1.5A.

At first, I was looking at an LDO. But for this much power draw, it would be really inefficient.

I then moved on to looking at a UBEC. Instead of having a linear converter on the PCB with the rest of my components, I was going to use a UBEC, which is a switch-mode power supply that sits inline between the battery and the microcontroller PCB.

However, I then thought about putting my own switch-mode power supply on the PCB. I made a circuit using WEBENCH that has an efficiency rating of over 90% and max power dissipation of just over 700mW. It is based on the TI LM20333. However, it seems a little complex and hard to solder by hand (since it uses several 0402 SMD packages). Also, I can't seem to find a power inductor that is not huge or expensive.

Would I be better using a UBEC, or making my own switch-mode power regulator circuit? Is there a certain simple and efficient circuit I should be using?


texts: Battery and Voltage Regulator for ESP8266 and HC-SR04

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I'm working on a project that includes an ESP8266 (requires 3.3v input (250 mA peak)) and a HC-SR04 (requires 5v 20 mA peak). I'm making it battery/solar powered.

I'm trying to keep costs down as well as make a system that works reliably and has good longevity.

I'll be waking the device every 15 minutes and keeping it in deep sleep at the other times.

Originally I was going to use a battery source over 6v, like a 6 cell AA rechargeable battery pack, a 10v or so solar panel, and a breadboard type voltage regulator that conveniently provides 3.3v and 5v on the same board. This seems to waste a decent amount of power though.

Right now I'm looking into using a 2 AA rechargeable NiMH batteries, a 5v solar panel, a 3.3v step up voltage booster, and a 5v step up voltage booster. 5v step up voltage boosters are everywhere and cheap because of their uses for portable cell phone chargers. 3.3v step up voltage boosters on the other hand are more expensive and harder to find.

Looking for any advice or affirmation that I'm on the right path. Thanks!


texts: Best way to terminate fine gauge polyurethane magnet wire

texts:
I am winding custom coils with AWG 32 polyurethane coated magnet wire and need to solder the coil leads to ~AWG 24 standard insulated wire so that they can be connected to a terminal block.

What are the best practices to solder the wires and also provide some strain relief?


texts: wifi antenna issue signal amp 10 dbi antenna

texts: I am running a dlink 2100ap with a (30dBm) 1W signal amp to a 10 dbi antenna. I am having issues picking up the signal on my laptop, could it be possible that the amp is making the antenna broadcast at a higher frequency? (it operates in the 2.4 Ghz spectrum up to 2.5). How far should my antenna reach?


texts: OPAMP has voltage on its supply when it shouldn't

texts:
I was trying to design a circuit after seeing this question. I know I used too much components than I should designing a circuit with this purpose. And sorry about the messiness of the schematic.

This circuit compares V1 and V2 and if V2>V1 than it outputs V2. If V1>V2, it outputs V1. I am going to combine U2 and U3's outputs later on. However I don't understand why this circuit behaves abnormally.

Even if the Q2's base shown to have about 20mV, Vbe of Q2 is negative, and V+ supply pin of U3 is 2.42V. Output of U1 is 8.39V and collector of Q3 is about 20mV. Output of U2 is 5V, where the output of U3 is 1.57V.

Why is this odd behavior?

Here is the LTspice file.


texts: Active RF Antenna power PCB layout: where to place the inductor for a bias tee?

texts:
I have an active RF antenna that is powered through an inductor in a bias tee network.

How should I draw it on PCB layout?

I have 3 ways to do that. In these layouts, up is capacitor, bottom is connector for antenna, right is inductor.

With a T join trace from the inductor

With the inductor on the RF trace

With the inductor on the far side of the connector

My signal is 1...2 GHz. What's the better/worst solution?


texts:
I have an old variable power supply that consists of a multi tapped transformer, a bridge rectifier and a choke. The transformer has two sets of taps on it, 6 coarse and 6 fine, giving 36 voltage outputs between 10v ~210v DC, maximum current is 8amps. Being such a simple design the output voltage obviously varies depending on the current being drawn. I'm looking for a way to add a regulator stage to the output so that the output voltage will remain constant and ideally so that I can have an adjustable current limit. Power supply is used for lab work and battery charging.

I'd consider linear or SMPS designs, simpler is better as my electronics skills are pretty low level.

I've had a look at some SMPS ICs and linear regulators, but I'm struggling to find one that can cope with the input voltage and current I require. Can I just series up a number of isolated regulators to get the Vmax rating I require?

If I use a SMPS design, would I just use the highest tap positions on the transformer, or is there still an advantage to using the taps to get closer to the desired output voltage?

Any suggestions on where to start would be greatly appreciated.


texts: How to cancel out only first High signal while receiving to remaining ones

texts:
I have an motion sensor that sends the high signal each time it is connected or turned on (beside the times when it actually detects motion).

The sensor is set to trigger an alarm each time it sends the high signal, so when it starts, it also triggers the alarm although no motion was detected.

Is there a way to cancel out that first signal so that only remaining signals with actual sensor data (after the first one) would be captured in the circuit?

The sensor and the alarm run on 6V DC. If possible, I would want to implement this with basic electronic components such as transistors, capacitors, resistors, etc, without having to buy some expensive IC.

Update: I have added the scheme

simulate this circuit – Schematic created using CircuitLab


texts:
I'm not sure if I understand the concept of grounding correctly.

Suppose I live in an apartment's 10th floor. Now the main panel is installed in the 1st floor of the building, and I want to setup a ground for the whole building. I put a copper rod into the soil at the 1st floor, with a wire connected to the main panel.
From the main panel the ground wire goes up to my room on the 10th floor, and connected to the ground pin of the 3-hole socket on the wall.

My first question is: When I'm standing in my room on the 10th floor, is my body at the same voltage potential as the ground pin? I don't think this is the case, because the ground wire doesn't make contact with the floor I'm standing, it only makes contact with the true ground wire on the 1st floor. So probably the 10th floor is at 110V and the ground pin is at 0V, and when I touch the ground pin I get a shock. Is that possible? If so, why is grounding safe?

Suppose somehow the 10th floor is also at 0V with respect to the ground wire. Now I operate a heavy pump with the chassis connected to that ground pin, but somehow the pump leaks current to the chassis, for example the hot wire might brush against the chassis.

Now how it the grounding supposed to protect me? The chassis is still at mains voltage (220V), and my feet touching the floor is at 0V.


texts: Why does the effective reluctance between two windings change?

texts:
The effective reluctance between the two windings should remain same, no matter on which arms they are placed. The pair of arms with less cross sectional area will offer more reluctance as compared to the other pair. Since in both cases, flux passes through both pair of arms so effective reluctance should remain same in both cases and hence the mutual Inductance.
Whats wrong with this explanation?


texts: Why are there only 3 wires on this power line?

texts:
When I was in Alaska, I saw a high voltage line, but I didn't see the Neutral.

Is this because the water is conductive enough next to it to use as neutral? Or is it just two Phases.

Where I live, Colorado, all of the power lines have the two neutral wires on top.


texts:
My understanding of motor run capacitors is that there is an optimal value for a paticular motor and that if it is not matched exactly, the magnetic field will vary and cause the motor to run poorly. Is this correct?

If yes, then how accurate does the capacitor size need to be? 10%? %5?


texts:
How can I modify this emitter follower circuit to get maximum amplitude output with no distortion?

Re = 2.25k ohms, Rb1 = 57.3k ohms, Rb2 = 96.1

I currently have 0.96 gain

Vcc is limited to 9V and nd a collector current of 2mA for RB1 and RB2, for a bias-stable network we use the × general rule  =  .


texts: How to detect that a voltage source is not powered?

texts:
I need to detect when the switch SW1 is on and when it is off, and this input has to be sent to a GPIO of a microcontroller. I have no idea how to implement the circuit required to achieve this goal, so I would really appreciate somebody else's help.

simulate this circuit – Schematic created using CircuitLab


texts:
I'm trying to drive MOSFETs with 3.3V PWM signal. Here is a (probably bad) circuit:

I know that a darlington is not the best thing to drive a mosfet with. But actually I need to drive many of them and the ULN2003A is very comfortable: 7 darlingtons in a single package, and it is cheap. I can buy them for $0.1/piece, whereas a dedicated MOSFET driver IC costs much more and can only drive a single MOSFET. In the above circuit, I have used R2=100 Ohm. I noticed that most circuits use at least 1K for pulling up the gate of the FET. But I want to be able to switch the FET relatively fast, at least 500Hz. The threshold voltage of the FET is about 2V, and the input capacitance is 1800pF. That is documented in its datasheet. What I don't see in the datasheet is the gate saturation voltage (maybe I'm looking at the wrong place). But I guess it is fully open at about 10V.

I may be totally wrong, but I tried to calculate the time needed to fully charge that capacitance through a 100 Ohm resistor:

http://mustcalculate.com/electronics/capacitorchargeanddischarge.php?vfrom=0&vto=10&vs=12&c=0.000001800&r=100

It seems that it reaches 10V in 320uS. That gives me 1.6KHz max. switch frequency. The charge/discharge peak current is 120mA. It is way below what an ULN2003 can handle. Peak power on the resistor is 1.44W. Which is quite high, but I want to switch at 500Hz only, and it easy to get a 1W resistor. I guess the extra power discipation on the resistor pays of because it opens the FET much quicker. The ULN2003A collector-emitter saturation voltage is below 3V, input current is less than 1mA and it can sink 500mA - more than needed.

But I still feel that I'm missing something. Usually I do not see others driving FETs with darlingtons. That must not be by coincidence.

Am I missing something? Would this circuit work?

And once again: I know that a dedicated MOSFET driver IC would work better, but using 20 MOSFET drivers for $100 vs. using 7 darlingtons for less than $1 makes a big difference...


texts:
in order to explain how to a pipelined multioperand adder could be implemented my book shows the image reported below. The idea is to use three adder with 4 stage pipeline.
However i tried to make a simple timing diagram by myself to check if i've understood well what my book meant, however i can't write a timed diagram so i'm quite sure i haven't understood good the concept.

So... question how that image should be interpreted?
Practical example?

I report what my reference says:
Figure 8.3 (the one i posted) shows that if the adder is implemented as a four-stage pipeline, then three adders can be used to achieve the maximum possible throughput of one operand per clock cycle. Even though the clock cycle is now shorter because of pipelining, the latency from the first input to the last output remains asymptotically the same with h-stage pipelining for any fixed h.


texts: Moeller IZM air circuit breaker malfunction

texts:
I have the Moeller IZM circuit breaker charged, but it there is no action happening when pressing the ON or OFF buttons.
what is the possible cause for that ?


texts: Piezo voltage through guitar vibration and Nyquist's theorem

texts:
I bought a piezo disk and intend to use it to determine the vibration frequency of a string instrument when a note is played.

https://www.sparkfun.com/products/10293

Can anyone explain how much voltage would be generated by a tuned Low E string (82Hz) compared to the high E (329Hz)?

And if I wanted to detect the frequency of the standard guitar notes I would need to sample the voltage at twice the highest frequency.
High E - 329Hz. So I need to sample at 658Hz? Or 658 samples per second to an analog pin of my arduino?

Thank you


texts: Phase difference from Lissajous figure of 8 in a CRO for which frequency relation is twice

texts: For the below figure of 8 Lissajous pattern, it is clear that the frequency of the Y input is half the X input. However how to conclude about the phase difference relation. The answer is option D, is it because the sense of direction is clockwise? How to conclude the phase difference for figure of 8. Is there a generalised method like in the case of ellipse where the phase difference is Sin inverse of intercept value by maximum value.


texts: USB disconnection when using differential probe

texts:
I have a simple setup described here :

Laptop is battery powered. It communicates with DUT over USB.

DUT is powered from switch power suppy.
DUT earth / GND resistor = 1M

Differential probe resistor between measurement GND and output (connected to scope) is 4M.
Differential probe is set to 100:1. It measures a +-100 voltage on A point.

When running : DUT periodically sinks some current during very short duration < 10ms. It's normal behavior, in this case I can get +-100 voltage on A point.  Otherwise I will have a 0 voltage on A point.

I have some issue with this measurement :

First the less important : I can see mains voltage on differential
probe (when I should have a 0 voltage measurement)
Most important : USB communication only works for a short time. After some seconds, I lost USB communication with DUT (I have not yet determined if DUT resets)

Of course, when differential probe is not connected to DUT, I do not have any issues.


texts: IRS2153(1) half bridge giving irregular output

texts:
I'm following standard design recommendations for a IRS2153(1) half bridge driver in the following setup:

The problem is that the output (measured at the joining net of Q1, Q2, L1, pin 6 and C3 negative relative to ground)  is unstable (it should be a steady pulse train, the horizontal scale is 200 ms to show that the irregularity appears at larger timescales: the resulting bursts in between are with the intended frequency):
It seems to be a saw-tooth like behaviour with a moving time base. I've tried many configurations (different input voltage, C1, R2, C2 and C3 combinations, together with replacing L choke with a R and skipping the potential divider C4 C5 with connecting the L straight to ground). Does anybody have similar experience with this IC? I've tried the IRS2153 too with a bootstrap diode and it still has a beat freuqency.

SOLVED: IC pin 1 needs at least 20 mA to function properly, a 56k resistor provides too little current. Around 12k 10W works for the given configuration.


texts: Step Down Switching Regulator irregularity with ripple on output

texts:
Using the L5973D- I have followed the Schematic as the datasheet instructs, but I have tried two different inductors. I have found problems with other systems on the board with the one inductor (744 561 15), such as Microchip while running in debug mode. The Schottky Diode (D1) used is the STPS340-SMB instead of the STPS2L25.

The requirements of the inductor are 15uH and 3A. So the first inductor selected was the DO3316P-153 (as recommended by the L5973D datasheet). The frequency out of the L5973D at pin one (circled in red on the schematic) is given in the figure below:

When the inductor is replaced with the more affordable inductor (744 561 15), the frequency at pin one is given in the figure below:

With the 744 561 15, there is this added ripple before the square wave, can anyone explain what is happening here?

Is the older inductor (DO3316P-153) filtering or is the new inductor(744 561 15) adding in a delay?

EDIT:

After running the Board for more than an hour and the system keeps resetting itself. At this point, I am not sure what is going on, any suggestions?


texts: Why do we use diodes when we connect a 7414 IC?

texts:
I was looking at a lab in Digital Circuits and there was a questions:

Why do we use diodes 1N914 in the circuit in figure?
What type of input signal to the circuit would make the diodes unnecessary?

So I believe that the answer should be:

Diodes are use a protection for the circuit when we have high voltage and that is able to rectify AC frequencies.
To use DC signals

But, I am not certain about these answers. Can someone help me with these questions?


texts: Is it possible to control a 4 wire Bipolar stepper motor with a PWM signal?

texts:
I am trying to control a 4 wire bipolar stepper with a PWM signal being output from a VEX  cortex controller. I am planning on using 4  bipolar NEMA 17 12v steppers to drive a small remote controlled robot. (https://www.sparkfun.com/products/9238)
I have found equipment to convert a 3 wire PWM signal to a (unipolar) 5-8 wire stepper output ( http://store.cunningturtle.com/collections/frontpage/products/radio-controlled-stepper-kit ), but nothing for 4 wire bipolar steppers. I am wondering if I would be better off looking for new motors or is there a way to control these motors easily with this controller.


texts: Input and output resistance of an opamp circuit

texts:
Recently we have been working with opamps in the lab and I never can understand how to determin the output and input impedance of a circuit with op-amps (not the input and output inpedance of the circuit itself)

We have been measuring it by placing a voltage signal in the output of an inverting amplifier with its imputs grounded. Measuring the voltage over an impedance we have found the current flowing in

simulate this circuit – Schematic created using CircuitLab

Then the output impedance is found to be the voltage at the output (Vout) divided by the current.

I would like to know what the input and output resistances in opamp circuits represent and if possible how to obtain them from equations


texts: What is this suspicious stain under a VFD's glass?

texts:
I wanted to give VFDs a try so I ordered a couple of 8x14 segments display modules.

They arrived today, but I'm concerned because each has a big black stain in the corner. If it were on an LCD I'd suspect they're broken, but since I don't know this display technology at all, can someone tell me:

Are those displays broken or is the stain a normal thing?
If this thing has a name, what is it called?

Here is a picture of the modules (the stain is on the top right corner):

Note that after checking on the seller website and a few pictures on other online resources, this kind of stain is visible on some of them, so it may be a normal thing.


texts:
I am using IXYH16N170CV1 IGBT's mounted at the edge of a PCB. The legs will be long and bent back to reach the heatsink shown in the image.

This device is rated for 1700 V and 16 A. My nominal voltage will be about 600 VDC and 11 A with a max of 1400 V.

The pitch spacing between the pins is 5.45 mm and the distance from the edge of the pins is about 4 mm at the narrow part and 3 mm at the thicker bit closer to the body of the device.

The distance between the 2 copper pours on Q1 is 2.5 mm. According to the distance calculator (image below) for 1400 V this is not enough.

Can these devices be connected to PCBs at this pitch and voltage rating?

Also, is there any implications for having the legs very long? Are arcs more likely?

Thanks.


texts:
I am asked to find the open circuit voltage v(AB).

So far, I have found the current, I(1) by using the current divider, and I got approximately: 0.307A.

Except, I am not sure where to go on from here to find the open circuit voltage.

Any help would be appreciated. Thank you very much.


texts: What is the function of this op amp and how it function?

texts:
I came across this radio schematic in electric circuit book. I'm a new to op amps. I tried to analyze this circuit and I succeeded partially but I couldn't figure out this op amp function(the middle one) (I think it's IF amplifier) and how it function.

Can someone explain it thoroughly for me.

explain to me how the output is shorted to the input and to the voltage divider?
if the op amp is to make the input voltage equal then there wouldn't be any current going through R9 right?since there is no voltage drop across it.

How can I calculate the output??


texts:
Power supply is quite infrequent in the area where I live so I want to create a power backup for my router(rated 9V, 1A). I'm planning to use solar, and possibly wind power. I searched for some solar panels and found some cheap ones rated at 9V, 70mA. How do I use these to create the required output?

Could you please help me with how I would set this up? I asked in the DIY Stackexchange and was sent here.


texts: SN75176B RS-485 Transceiver - Low Level Driver Oscillations

texts:
I'm trying to interface an Arduino Mega2560 to a Modbus RTU device using an SN75176B transceiver, on a solderless breadboard at this stage.  When I'm driving DE high and writing serial data out of the Arduino, the highs are nice and clean but the lows are full of 3MHz noise.  It looks like this:

The blue line is the arduino output, the yellow is the transceiver output (A to B).  The arduino's UART is running at 9600 baud.  Obviously the device connected has trouble understanding this.

According to the data sheet, all this device needs is a bypass capacitor between VCC and GND.  Admittedly the one I'm using is a bit overspecced, but would that cause this?

(Note: I have 120ohm termination resistors at both ends)


texts: Help understanding this schematic : Why is the diode there (AT89C2051 Programmer)?

texts:
I am having trouble understanding the following portion of schematic from AT89C2051 programmer circuit. Please help me comprehend what is going on here.

Here is what I understand:

A1 directly controls the 12V going to AT89_RST pin
When A1 is low,

If A0 is high, AT89_RST pin sees high.
if A0 is low, AT89_RST pin sees low.

So why is the 5V added there with the diode? I suspect it might be one of the following two reasons, but I really don't understand why.

To pull up AT89_RST to 5V. But A0 can be driven both high and low. Why pull it up?
As some form of protection to prevent A0 from getting roasted with 12V? I think it might be the case, but I don't understand how it works to prevent that.

Notes:

AT89C2051 Programmer's Github.
A0 and A1 are being driven by arduino (5V logic).


texts: Class AB amplifier using push-pull pair signal decay

texts:
I'm trying to build a class AB amplifier with push-pull pair of power transistors for audio amplifier.
the circuit works fine with low voltage(~0.2V) but the input peak voltage varies between 0.2 - 2V.
at 2 volts the circuit starts fine but the voltage decays so quickly and signal distortion happens.
when i insert h.p.filter, smaller capacitors bottleneck the signal.
the pair is DC biased with 1.4V difference between npn base and pnp base.
There're two stages(common emitter amplifier and common collector) before this stage.
Graph A is the circuit after one minute.
Graph B is the circuit at the initialization.


texts: ADC10 and DTC (MSP430 F2xx) - problems in reading analog input on multiple channels

texts:
We are trying to read analog voltage supplied to two channels simultaneously using ADC10 and DTC.

We are not getting the results of conversions. Our code is as follows:

ADC10CTL1 = INCH_2 + CONSEQ_1;
ADC10CTL0 = REF2_5V + SREF_1 + ADC10SHT_2 + REFON + ADC10ON + ADC10IE;
ADC10AE0 |= 0x06;
ADC10DTC1 = 0x02;
ADC10SA = 0x200;                        // Data buffer start

while (1)
{
    ADC10CTL0 &= ~ENC;
    while (ADC10CTL1 & BUSY);
    ADC10SA = 0x200;
    ADC10CTL0 |= ENC + ADC10SC; //Sampling and conversion start
     __bis_SR_register(CPUOFF + GIE);        // LPM0 with interrupts enabled
}

and, the ISR is:

#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A (void)
{ int * read = 0x200;
//code that reads from the location 'read'
 __bic_SR_register_on_exit(LPM3_bits);        // Clear LPM3 bit from 0(SR)
}

While we are getting the results back at AP, they do not show the correct value, and the value doesn't change if the supplied voltage changes.
How do we make sure that an interrupt is generated only when the conversion is complete?

Thanks a lot for your time.


texts: How do I remove the feedback noise in my circuit?

texts:
I want to transfer power via induction.

I have done this successfully multiple times with multiple designs. For various reasons I am steering clear from more traditional methods, for one, so that I could potentially have a lot more current flow through my induction coil (which is just a single hollow copper loop) reliably.

Using a crystal oscillator and a volt regulator a have gotten a Flip Flip to perfectly oscillate Q and notQ to switch on the gates of my fast switching Logic Level MOSFETs. I have confirmed the Flip Flop outputs with an oscilloscope. I smoothed the power supply (10V) with a 2200 uF electrolytic Cap and added a parallel tuning cap for the LC tank. My circuit is working and transfering power wirelessly.

However, I am not opperating at the efficiency I expected.
Previous models of mine that only use one MOSFET and one output of the flip flop are even performing much better. This design however is "off" half of the time, when the volts over the gate are zero. The MOSFET has to block a lot of current, gets really hot and prevents current flow at the level I would like.

My logic tells me that my design belowe should be on almost 100% of the time. First allowing current to flow top to bottom on my schematic, then vice versa. The flip flop first puts on the two top MOSFETs with Q, and then the bottom two with notQ.

I have built this design and it does work, but not as well as I hoped.
I believe there must be some noise or feedback in the system preventing it from smoothly oscillating. Any help how I could potentially fix this problem would be of great help. Many thanks.


texts: Layout of Power lines to extension board (Temperature Sensor)

texts:
I'm designing an (single sided) extension board that will hold a 3-pin temperature sensor (TSIC 506). As the order of the pins go from 1 Vcc, 2 Signal, 3 GND I wonder if I should follow the same order in the cable connecting the board to an MCU? Or would it be better to have 1 Vcc, 2 GND, 3 Signal on the cable?

As a more general question, should ground and power lines in a cable also carrying signals be next to each other, or as far as possible from each other?

I attach two layouts of the board I did.

First, power lines apart:

Second one, with power and ground next to each other:


texts: out growing 8-bit AVRs, not sure where to move on to

texts:
I've been using 8-bit AVRS for a few years now. Lately, I've been feeling limited by the peripheral data transfer speeds and higher level libraries.

I'm having trouble finding/picking a new line of microcontrollers to explore.  I've looked at

NXP        - Can't find a programmer
Freescale  - Have to register for IDE
AVR32      - Limited chip selection on digikey

The NXP chips look really nice, but as with anything that isn't PIC/AVR/Ardiuno the learning curve is pretty steep.

I was wondering if anybody could suggest a line of micro controllers that satisfy (in order of importance) the following requirements

Hand solder-able chips. (I can do LQFP 100)
32 bit
Linux host
Free toolchain
Good/free IDE
<500$ startup cost for unlimited programming/debugging/compiling
CAN support
Ethernet/USB support

I'm willing to look at Freescale and NXP again, if somebody can show me that I've missed some information on their toolchain and programmers. I guess you could say AVR32s are exactly what I'm looking for, but I'm just not happy with their chip selection. They all have higher pin counts and low stock on digikey.

Thanks.


texts: How to design an SMD prototyping board in Eagle

texts:
I have little boards that allows soldering one SMD chip, but these must be soldered to pins and then the pins plugged into a breadboard or soldered to a perfboard.

Instead, it occurred to me to design a generic PCB in which there are a number of SOIC chip placements, with the leads fanning out until they are separate enough to solder wires to  I don't know if this is a terrible idea, but good or bad, I can't even figure out how to do this easily.  Eagle does not allow building out traces without the wires being connected to the other side.

So first, as a practical matter, is there any way in Eagle to lay out traces directly, not connecting two wires.  I want to design in bus lines for power, for example, and then connect.

Second, if this is a terrible idea please explain why?


texts:
I have a question regarding this constant current source circuit:

I have seen this circuit with two BJTs (like in the figure), but sometimes T2 is a MOSFET (I assume for lower Rdson resistance and better switching performance).

However, my questions is: could both transistors T1 and T2 be MOSFETs? Is it recommendable or, would the circuit stop working properly?

Thanks!


texts: Why can the loading resistor and capacitor let the unloading waveform become from negative to positive voltage?

texts:
Fig(1) is part of schematic,and it generate a sine wave .Fig(2) shows two waveform which are with load and unload,i can understand that these two waveforms will be different because of loading,but why is the beginning of unload waveform  negative,and after connecting the resistor and capacitor,the beginning of the waveform will become positive?

fig(1)

fig(2)

link:Misunderstanding from the author saying,about the current flowing path


texts: Dump Flash Memory through a single GPIO pin

texts:
I'm working with Infineon's XMC4500 Relax Kit and I'm trying to extract the firmware through a single GPIO pin.

My very naive idea is to dump one bit at a time through the GPIO pin and somehow "sniff" the data with a logic analyzer.

Pseudocode:

while(word by word memory copy hasn't finished)
  ...
  register = value;
  temp_value = value AND 0x1;
  pin = temp_value;
  value = value >> 1;
  ...

Am I on the right track? Does anybody have a better/nicer idea how to archive this?

### EDIT ###

Actually a requirement of my (shell)code would be that it needs to be really tiny. I found this nifty trick on how to
dump firmware by blinking the LEDs.

However I'm struggling to receive correct values with Saleae Logic Analyzer.

Basically what I'm doing is:

Setup the GPIO pin directions to output
Blink LED1 (pin 1.1) with a clock (SPI serial clock)
Blink LED2 (pin 1.0) with data bits (SPI MOSI)
Sniff pins with a logic analyzer

Here's my C code:

#include "XMC4500.h"

#define DEL 1260

void init()
{
  // P1.0 output, push pull
  PORT1->IOCR0 = 0x80UL << 0;
  // P1.1 output, push pull
  PORT1->IOCR0 |= 0x80UL << 8;
}

void delay(int i) {
  while(--i) {
    asm("nop\n");
    asm("nop\n");
  }
}

// Sets a pin to high
// P1.0 = SPI MOSI
// P1.1 = SPI CLOCK
void output_high(int i) {
  // P1.0 high
  if(i == 0) {
    PORT1->OUT |= 0x1UL;
  }

  // P1.1 high
  if(i == 1) {
    PORT1->OUT |= 0x2UL;
  }
}

// Sets a pin to low
// P1.0 = SPI MOSI
// P1.1 = SPI CLOCK
void output_low(int i) {
  // P1.0 low
  if(i == 0) {
    PORT1->OUT &= (~0x1UL);
  }

  // P1.1 low
  if(i == 1) {
    PORT1->OUT &= (~0x2UL);
  }
}

// SPI bit banging
void spi_send_byte(unsigned char data)
{
  int i;

  // Send bits 7..0
  for (i = 0; i < 8; i++)
  {
    // Sets P1.1 to low (serial clock)
    output_low(1);

    // Consider leftmost bit
    // Set line high if bit is 1, low if bit is 0
    if (data & 0x80)
      // Sets P1.0 to high (MOSI)
      output_high(0);
    else
      // Sets P1.0 to low (MOSI)
      output_low(0);

    delay(DEL);

    // Sets P1.1 to high (Serial Clock)
    output_high(1);

    // Shift byte left so next bit will be leftmost
    data <<= 1;
  }
}

int main() {
  init();

  while(1) {
    spi_send_byte('t');
    spi_send_byte('e');
    spi_send_byte('s');
    spi_send_byte('t');
  }

  return 0;
}

### 2nd EDIT ###

Finally sorted it out. Dumping flash memory is working fine with the following code:

#include "XMC4500.h"

// SPI bit banging
void spi_send_word(uint32_t data)
{
  int i;

  // LSB first, 32 bits per transfer
  for (i = 0; i < 32; i++)
  {
    // set pin 1.1 to low (SPI clock)
    PORT1->OUT &= (~0x2UL);

    // set line high if bit is 1, low if bit is 0
    if (data & 0x1) {
      // set pin 1.0 to high (SPI MOSI)
      PORT1->OUT |= 0x1UL;
    }
    else {
      // set pin 1.0 to low (SPI MOSI)
      PORT1->OUT &= (~0x1UL);
    }

    // set pin 1.1 to high (SPI clock)
    PORT1->OUT |= 0x2UL;

    data >>= 1;
  }
}

int main() {
  // start dumping at memory address 0x08000000
  unsigned int *p;
  p = (uint32_t *)(0x08000000u);

  // configure pin 1.0 and pin 1.1 as output (push-pull)
  PORT1->IOCR0 = 0x8080UL;

  while(1) {
    spi_send_word(*p);
    p++;
  }
}


texts: in Powerworld there is a function called ''line flow pie'' which indicate the percentage of load of the line. But what is it? I think that it is the ratio between the current on the line and its nominal value times 100. Is this correct?


texts:
edit:
OK, I am making it simpler. Currently, the input varies from -1 to +1V, and the output is (obviously) -1 to +1V. I want the output to vary from 0 to +1V. Not just shifted up with a dc bias and gain halved. The negative half cycle should be folded up to the positive side... similar to what happens in full wave bridge rectifier. But that is floating, like my previous wrong circuit shows. I want the output (0-1V) to not be floating but ground referenced.

example:

input    output
0        0
0.5      0.5
1        1
-0.5     +0.5    (sorry about previous typo in this line)
-1       1       (sorry about previous typo in this line)

hopefully this will explain

original post

Signal varies from 8 to 10V. I need the absolute value with 9V reference. i.e. 8V signal should give me 10V output, as well as 10V signal should give me 10V output. Is there a better way to do it?

i.e. any sway from 9V gives me the magnitude, disregarding whether it is up or down.

[edit: this circuit will not work. I need the output to be ground based.]

PS: I may have to put in a 1k feedback resistor, but ignoring it for the moment.

I want to actually build a 2 quadrant power supply, and having difficulty regulating the sink current. The rest is working fine.


texts: Time it takes for B to go to zero with R and L given

texts:
Given that your solenoid has inductance L and resistance R with initial current I such that there is uniform B inside the coil, I would like to figure out how much time will pass before B goes to zero.

Using the equations shown here, I think I have some idea of how to solve for \$\Delta t\$.

First, we know that the energy stored in the inductor is \$ E = \frac{1}{2}LI^2\$.  Then, power, the rate of energy change, is \$
P = L I \dot{I} \$.  Also, we know that \$
P = I^2 R \$.

From the link above, given the energy density inside the coil spring (solenoid), the energy stored can also be written as \$
E =\frac{B^2 V}{\mu} \$, where \$V \$ is the volume.

Take its time derivative, \$P = \frac{BV}{\mu} \frac{dB}{dt} = I^2 R \$.

Since \$ I = \frac{Bl}{\mu N} \$, \$P = \frac{BV}{\mu} \frac{dB}{dt} = (\frac{Bl}{\mu N})^2 R \$.

Can I now just solve for \$ dt \$ to figure out the time lapse for the magnetic field to go to zero?


texts:
How can I find out if library has already been compiled in ModelSim/QuestaSim to speed up simulation scripts?

I have some files that contain multiple vlog commands to compile several libraries and than a vsim command to start simulation later adding the signals to wave window and cursors and running the simulation. There are certain library files that contain the primitives that need to be compiled and take a while. Is there a way to use 'if statement' with some function to see if a library already exists since it has already been compiled, and that this library was compiled using files from a certain location? I am carrying out many different simulations and often the libraries may be the same (depending on which order is being used).

Otherwise, is there a way to compile these into a library in ModelSim/QuestaSim at startup by default?


texts:
How can I shift whole my design using ISE(FPGAditor,plan ahead,..) to new placement?
I want to no change in routing but change only in placement.
Thanks.


texts:
Please suggest if the layout is fine:

it is 25MHz 3225 crystal.
I maintained short traced for XIN and XOUT.
I maintained a guard ring around the crystal.
I have grounding in layer just below.
the dotted shape is also ground.


texts:
I'm thinking about replacing an 915MHz RF module on a PCB I designed with an equivalent circuit directly implemented on my PCB to overcome some supply chain issues. The module I'm replacing has an EMI shield covering it, so I'm thinking I should at least include provisions for an EMI shield on my PCB as well (i.e. at least a footprint). I went over to Digikey and I found this and this by way of parametric search and availability considerations.

The main question that brings me here is the fact that there are these "vent holes" in the top of this EMI shield, whereas the module I'm replacing has no vent holes in the top. Will the vent holes compromise the effectiveness of the EMI shield? How significant of an effect is that?
A secondary, related question I have is whether an EMI shield like this can be included in an SMT assembly process as a component? Would it compromise the reflow of the parts under the EMI shield or does it have to be a added as second pass through the reflow oven?


texts:
I have an electronic system waiting to be triggered (no microcontroller for now).
My laptop only has USB ports.

I want to trigger it using voice recognition (this part is ok).

For now the only think I can think of is :

Once the right keyword is detected, send a 19 KHz sine on the audio output, because it's inaudible, for 0.1 seconds and uses a microcontroller analog port to detect it.

I only have microcontroller with no USB support available and I've never used a USB connection.

I'm not looking for something perfect, a dirty solution would be all right, this is just to do a prank tomorrow.

Thanks.


texts: Mount position inertial measurement units (IMU)

texts:
currently I am reading about IMUs and got confused about the mounting position of the IMUs.

In this paper (https://pdfs.semanticscholar.org/c2b6/9d5f4cf0fbbbad97d1fc10b3757f9c41bb8f.pdf) , the author mounts the IMU on the center of joint rotation.

But in some other papers, the IMUs are mounted at the center of geometry of links.

Why does this mount position matter? To my knowledge, the rotation of a rigid body should be always the same.


texts: How to save electronic equipment from ants?

texts:
Today I brought out my external HDD and it was full of red ants. It took me an hour to remove the ants (it seems quite impossible to remove all of them; some are still inside). I always see some ants are coming out of my laptop. My sister's laptop is infested too. Some keys are not working. So, it's a big problem. I have two questions:

Does anyone know how to prevent red ants from entering electronic equipment like laptop, HDD etc?
How to remove the ant colony that are inside the laptop, HDD?

I'm not sure if this is the best place to ask this question, but I don't see any other option.


texts: Trying to interface a simple push button with PIC12F675 controller in Proteus, but not getting output

texts:
I am trying to interface a PIC12F675 controller with a simple push button as input and a LED as output. I am trying to simulate this on Proteus to save time. Although my code works perfectly fine with the PIC16F877a contorller, it's derived version for PIC12F675 doesn't provide the expected results. I have written the code in MPLAB X IDE and compiled using XC8 compiler.
My code is as shown below  :

# include <stdio.h>
# include <stdlib.h>
# define _XTAL_FREQ 8000000
# include <xc.h>
 // BEGIN CONFIG
# pragma config FOSC = HS // Oscillator Selection bits (HS oscillator)
# pragma config WDTE = ON // Watchdog Timer Enable bit (WDT enabled)
# pragma config PWRTE = OFF // Power-up Timer Enable bit (PWRT disabled)
# pragma config BOREN = ON // Brown-out Reset Enable bit (BOR enabled)
#pragma config CPD = OFF // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off)
#pragma config CP = OFF // Flash Program Memory Code Protection bit (Code protection off)
#pragma config MCLRE = OFF
//END CONFIG

void main(void)
{

//
  TRISIO0 = 1;    // PIN 0 INPUT
  TRISIO1 = 0;   //PIN 1 OUTPUT

  GP1=0;

    while(1)
  {
      if(GP0 == 0) //If Switch Pressed
      {
          GP1 = 1; //LED ON
          __delay_ms(3000); //3 Second Delay
          GP1 = 0; //LED OFF
      }
  }
}

Here, I am trying to read the switch from pin 0 and provide LED blink on pin 1, if switch is pressed. The push button is pulled up via a 10k resistor and an external crystal of frequency 8MHz is connected.

On execution of this code on Proteus, the LED is permanently ON and there's no effect on pressing the switch. Although, by writing a code for simply blinking the LED on pin 2, the code works fine.

How do I get the switch to read correctly?


texts: Transition from programming microprocessors via switches, to programming them with software

texts:
So I'm trying to understand at a hardware level, how the change from programming microprocessors via switches to programming them by writing software occured. I can wrap my head around using physical switches to switch signals but how is it possible to write software or write code and get the computer to respond to it physically? I understand that you need an operating system and that the operating system tells the microprocessor how to physically respond to the code, but how does it do this at the physical level? Also how do you make a microprocessor so that it is run by an operating system in the first place?

Update: From my understanding, programming through software works this way, when I press a key on my keyboard, a sequence of signals are sent to the microprocessor, what I see on the screen or the program that I am writing is simply a human friendly representation for the signals being switched along the various lines of the microprocessor. So any sequence results in a series of signals are interpreted by the microprocessor and the microprocessor does different things based on how it was programmed. Is this how it works? Also, if I write a program and run it later, where do the 0's and 1's in the machine code, get converted to physical signals?


texts: How to design a simple current based class A amplifier

texts:
Very much along the lines of Class A single transistor amplifier with 2N3904, but with a current signal input.  My circuit is a Zener noise source using the simplest of  components.  Traditional class A design starts with locating the Q point based on a voltage signal.  I'm not sure how to proceed due to the R1/R3 relationship affecting the Zener current which should target 60uA DC. Is this architecture even possible?

My parameters are as follows.  The Zener current is empirically determined for maximum noise using the ones I have.

Target gain = 10x.

Vcc = 30V.

Noisiest Zener current and Ib = 60uA DC with 10uA avalanche signal.

Bandwidth 100kHz.

I can foresee a design situation where R1 = 0 and becomes redundant. I have considered  a FET based design, but was curious about a BJT design and due the fact that Horowitz & Hill do not recommend them (§ 3.08, 2nd Ed.)


texts:
Is there a way that I can add protection circuitry to a non-protected ICR cell?  I purchased an order of Panasonic cells at a discount, and I would like to keep them safe.

Would buying cheep cells, such as "UltraFire" 18350 cells, taking the circuit and putting it on my nice cells be a legit solution?


texts:
Its required to find \$v_o\$. The question should be easy but I am not getting the same answer as offered by the textbook which is 2cos(400t-53). I am getting 5cos(400t-53). I tried doing in two ways: 1)reflecting the right impedance to the left and then converting the votlage back to the right circuit, 2) Using KVL and ideal transformers equation. I will show the latter here.

\$\frac{V_1}{V_2}=\frac{N_1}{N_2}=2\$. So, \$V_0=0.5V_1\$
But, we also know that \$I_2=2I_1\$. And that \$V_0=5I_2\$ where \$I_2\$ is the clockwise current in the secondary circuit. This implies that \$V_1=20I_1\$ (Eq 1)
Using KVL, in circuit 1:
\$-25\angle0 +40jI_1+10I_1+V_1=0\$ (Eq 2)
Putting Eq 1 in Eq 2, and calculating \$I_1\$, we can then find \$V_1\$(using eq 1) and then \$V_0\$ which is half of \$V_1\$.

Have I done a mistake or is the answer in the book wrong?


texts: Transformer rectifier set. A question about the schematic diagram

texts:
This is a high voltage transformer (53kV) and rectifier that is used to power an Electrostatic Precipitator. The schematic shows a jumper between terminals H1 and H2 with a label "Remove jumper for half wave operation". Can anyone explain the benefit of operating the rectifier at half-wave rectification?

Also, the schematic shows 2 separate surge arrestors. Why is this?


texts: 50hz noise removal from ECG power supply

texts:
We are currently working on a bio medical project that is an ECG machine.There is a problem that we are unable to solve on software side is the removal of 50 Hz noise. Now we are trying to remove 50 Hz noise using analog filters. Does anybody have an idea of removing 50 Hz noise using analog components.

(the original title stated that the problem was in the signal  — Steven)


texts: A contactor switches 800 amps from two 26 volt batteries in series in a resistive circuit. Can I use a mosfet

texts: The batteries are Lithium Iron Phosphate 26 volts each. There is no inductive or capacative load. The gating circuit should use either the 26 volts or the 52 volts. The switch will operate 8 times per minute. The time from zero current to full on is not critical, nor is the time from full on to zero. Is this possible? can anyone suggest a suitable gate circuit?


texts: How can I map bits in a byte to turn on or off a pin?

texts:
I have a byte of data as input and each bit represents the state of an led. The pins that control the leds are spread out and on different ports.

I have C code that changes the state of 6 leds. these leds are mapped to 6 pins which are in the same port and are sequentially assigned.

Im porting this code to a micro where the available pins aren't in the same port.

thanks


texts: I would like to buy DSO138 oscilloscope to measure DC converters output voltage. What is the max frequency?

texts:
The DSO138 scope: enter link description here

in the description there is: 'Analog bandwidth: 0 - 200KHz'

What does it mean?

If I would like to measure DC converters output voltage and the DC converter operates at 500kHz or 1mHz than I can't able to measure the output ripple?


texts: 8085 μp; Why does Read cycle take 3 T-states and not 2?

texts:
In the text I'm following, R.S.Gaonkar it's explained that,

During T1, address in Program Counter(PC) is latched onto the Memory Address Register(MAR),
During the falling edge of T2 \$\overline{MEMR}\$ becomes active, and during the rising edge, contents in the Memory Data Register is placed on the bus \$^\dagger\$
During T3, contents in the bus is latched on to the accumulator.

\$^\dagger\$ My question is, during the rising edge of T2, why is the MDR not directly latched onto the accumulator, but takes another T-state to latch it on?


texts: "Safe" (but slower) charge method for AGM batteries?

texts:
My understanding of AGM vs flooded lead acid (FLA) batteries is that FLAs like to gas/outgas but AGMs do not.  It is pretty much a requirement to increase the charge voltage of FLAs so that they gas and "de-stratify".  However for AGMs, that is not a requirement, nor is it recommended.

So my idea is for AGMs, if you are not in a hurry to charge them, why not just set them at the trickle charge voltage and let them slowly charge (such as overnight)?  An example would be I used my battery bank during the day and it is resting at 12.3V (a mid state of charge for AGM).  Now suppose I have a 13.6V 10A power supply (ps) and just connect it to the battery for many hours.  In theory, I don't have to worry about overcharging the battery since 13.6 is already the battery manufacturer recommended trickle charge / maintain voltage.

I have also tried this method with Lithium Iron Phosphate batteries, setting the charge voltage to 14.2V and watching the charge current eventually drop to 0.000A.

For AGMs and LiFePO4 (LFP) batteries, it seems like a good safe technique since you are guaranteed not to overcharge the batteries and it is healthy for AGMs to keep the charge voltage lower so there will be no loss of water.

So my question is are there any drawbacks (other than slower charge times) for using this method?  What might it do to the life of the battery charging it ONLY this way?


texts: What keeps the kickback voltage from reaching an infinite voltage?

texts:
We know that the voltage over an inductor is defined by the formula:

\$V = L * \frac {di}{dt} \$

So in the case where the current flow is suddenly interrupted (like when a mechanical contact is opened), voltage spikes occur in real life.

However, this is not always the case: we don't see arcs happen in small inductive loads. (By small inductive loads I mean a toy car motor, for example.) However, the formula says that the \$ \frac{di}{dt} \$ term should approach infinity when mechanical contacts are opened, therefore the \$L\$ term (which should be small in small inductive loads) shouldn't have a significant effect. Simply, we should be able to see sparks any time we open any inductive load - independent of the inductance.

What are the practical factors that stop the voltage from reaching infinity? Does the current flow actually decrease slower, or is the formula perhaps insufficient for such a "discontinuity"?


texts:
In my other topic i asked on how to create a sawtooth signal and guys on the forum gave me an excelent anwser. But! I cannot fully understand the first part of a circuit which is supposed to be an "constant current source". I know in theory what it should do but i cannot seem to understand this circuit:

Correct me if i am wrong but i think that capacitor is where a constant current's load should be. And current through load should be constant... This is all i know (for now) and i want to know how exactly does this circuit achieve constant current through a capacitor? I know allso that current doesn't actually flow and that sooner or later when capacitor reaches saturation current stops.


texts:
I put together the following circuit that creates a single pulse of a fixed width when switch S1 is pressed.

The basic idea is simple. A HIGH at the Q1 base will turn ON Q3, discharging the C2 cap. Once the output of the 7414 goes HIGH, Q2 turns on, turning OFF Q3, and thus the C2 will get charged once again from the current through R7.

The Yellow trace is the voltage at point A.
The Red trace is the voltage at point B.

The following image of the the Q3 base, we can see, that when the base is HIGH, the capacitor C2 is discharging and then charging once the base gets LOW.

The Yellow trace is the voltage at point A.
The Red trace is the voltage at point C.

Now my question.

We can see the cap C2 is discharging to about 1.28v and then charging to 3.12v when the output of the 7414 gets low.

According to mu calculations, the time it should take for the 10nF cap to get charged from 1.28 to 3.12v through a 1k resistor is about 6.8us.

$$ 3.12 = (5-1.28)(1-e^{t/RC})+1.28$$
$$ t = -ln[1-\frac{(3.12 - 1.28)}{(5-1.28)}] * R7 * C2 = 6.82\mu s$$

But it is actually taking about 4.3us.

Why is the cap charging faster?
Is it can be because I am doing to on a solderless breadboard?

I have checked with more than one capacitor and resistors, so faulty parts is not in question.


texts: What are the contact pads near the ATmega32 chip on the Arduino Yun?

texts:
What are/What use have these pads near the ATmega chip?

I thought they are used for testing or something else, they seems to expose the ATmega traces directly.

Maybe they can be useful to connect to the chip by directly soldering a ribbon cable to the pads.


texts: Designing a three stage BJT transistor amplifier

texts:
My final project for my electronics class is to design a three stage transistor amplifier.

I'm not asking for answers, or for someone to do this project for me.
I need help starting the project and a general set of steps that I can follow for deriving an expression for V_out.
When I draw a miller equivalent circuit for this amp, V_out is across that 50k resistor at the emitter. Previous circuits in the class have had V_out taken from the collector, which made it easy to derive an expression for V_out after multiple voltage divisions.
Additionally, is there any way that I can calculate the resistor values? Or should I load the circuit up in a Spice program and guess resistors until I get an acceptable A_mb and f_L?
My study group is super lost on this :( We haven't gotten any circuits this complex and with so many missing values during the semester.


texts:
I'm not quite sure how external interrupts will work with several peripherals on the same EXTI line.

For instance, if I configured interrupt on line X and on the same line(of course another GPIO port) I have SPI MOSI or SCK, or maybe ADC working, would I receive interrupt every time one of these pins was triggered? And if I do then is it possible to get information about what pin was actually triggered?

Thanks.


texts:
The performance of my self-made JTAG cable isn't great, I can clock it up to 1.5Mhz max. I've read that terminating the clock line is a thing so I investigated:

One solution suggested to add a series termination resistor of 220 Ohm (or so).. Haven't tried that yet, but it makes sense.
Another solution recommended this:

simulate this circuit – Schematic created using CircuitLab

That makes perfect sense to me. It's like ordinary termination with a high-pass built in.

Something makes me wonder however:

The capacitor isolates from the actual DC level, so it should not matter if I connect it to ground, 1V, 10V or whatever as long as 'whatever' is of low impedance, right?

Could I connect the capacitor to - lets say - my 3.3V CPU supply instead of ground or is that a terrible idea?

Reason I ask is, that on my cable the clock line is directly beside the 3.3V so decoupling against that reference would fit better.


texts: NFPA70E Question: My company provides electrical inspection services, does my technician need to wear a hot suit?

texts: So my company provides preventative maintenance inspections, wherein the technician will open a large number of electrical panels, rated from 120-480 volts, sometimes up to 30 panelboards in a single facility, transformers as well. I'm trying to push us more and more toward compliance with NFPA 70E, minimize risk, all that. An exception is given in 70E for infrared inspections only, however this does not include removal of covers or voltage testing, which is part of the inspection as well. So hypothetically, he throws on a hot suit, takes the cover off, tests the voltage, takes the hot suit off, makes notes, takes his thermography imaging, puts the hot suit back on, puts the cover back on, and moves to the next panel....30 times. I am hoping to get advice on either better workflow from someone more experienced in this type of work, or if at all possible, a loophole or something. I want my workers to be safe but this kind of expenditure of effort and time wasting, I can only think that we can offer a competitively priced service if I can figure something crafty out. Otherwise we might as well not offer the service.


texts: Low energy arithmetic/logic gate level design

texts:
I'm looking into various gate level (NAND, NOR, AND, INV) designs for low energy arithmetic/logic blocks, especially adders. Low energy indicates the use of minimal energy per operation executed.

Holding $V_{dd}$, technology and clock speed constant, which of the following adder designs are more energy efficient: Ripple, carry lookahead, carry-select, prefix adders? And why is that so?


texts:
attempt:-

BY applying virtual ground i will get Vo=2v
now applying nodal at non inverting terminal i will get (V-2v)/R=I now from this i will get V/I=-R.
but the answer given is Option B mean only R

whats mistake i am doing?


texts:
This might sound silly but I am new to electronics and trying to understand the difference between watt-hour vs ampere-hour when it comes to battery life per charge.
So let's consider this scenario.
I have a circuit that runs for 7 days when connected to a 3.7 V (1200 mAh) battery. Here the watt-hour of the battery is (3.7 * 1.2) 4.44 Wh.
Now if I connect a 12 V (1200 mAh) battery which provides (12 * 1.2) 14.4 Wh and use a voltage regulator, will I be able to run the circuit for more than 7 days on a single charge?
EDIT:
The circuit voltage requirement is 3.7 to 4.4 V and consumes 500 mA when active for 10 seconds and then it goes into a deep sleep for 5 minutes. During deep sleep, it only consumes around ~50 uA. My goal here is to get the maximum battery life (more than 60 days) from a single charge.


texts: FCC labeling for exempted product (test equipment)

texts:
Thinking to start selling my widget and pondering these questions..

I have understood that there's no labeling needed for "A digital device used exclusively as industrial, commercial, or medical test equipment".

However, leaving FCC label/mark out and not saying anything about that on the product, would look like FCC rules were not even considered.

In this case is it customary to say in the label "FCC exempted test equipment" or just "Test equipment", or something like that?

Thanks...


texts: Interpolation of electrolytic capacitor's dissipation factor / loss angle

texts:
It is a common practice for capacitor manufactures to define either the ESR or the dissipation factor (aka loss angle) at a given frequency (e.g. 120Hz, 1kHz or 1MHz). It is also clear that their dependence on the frequency is not linear.
The question is, is it possible anyhow to use some sort of interpolation to have a first-order approximation of the ESR at a frequency other than the one stated in the datasheet?

Thank you.


texts: Is it possible to use all the outputs from a power supply at the same time?

texts:
I wonder if is possible to utilize all power supply from this device: Power supply

I need the 5V output to power a relay board for a Raspberry Pi, and the 24V output to power a motor shield, both connected to the same power supply. Is this possible or must I buy two separate power supplies?


texts: What is address allocation of memory register?

texts:
What is ment by address allocation of memory register in microprocessor and memory topic or in computer architecture?

Memory chips are have no processing elements(passive elements). How memory chips are getting address allocation that selects a specific memory location.


texts:
What would happen to a BJT if both junctions of the transistor are forward biased? Is there any literature on this? By literature I mean characteristics/equations. Any links would help. I have also drawn circuit diagrams to make my point clear.

simulate this circuit – Schematic created using CircuitLab

Where I was taught in college, we worked on

active region (BE-forward biased, CB-reverse biased)
cutoff region (BE-reverse biased, CB-reverse biased)
saturation region (BE-forward biased, CB-on the verge of a reverse bias)
What happens if CB and BE are both forward biased? Is there any literature or quantitative analysis method for that? What happens if BE is reverse biased and BC is forward biased? Is there any literature or operation zone defined for that.

The reason I want to inquire is because I was recently working on an Op-amp circuit attached to a BJT and there was a case where both the junctions were forward biased and I could not fathom how to analyze it because of basic complexity, in fact I did not even consider the case that both the junctions could be simultaneously forward biased and I only came to that conclusion when I simulated my circuit, hence I want to know how the regions operate so that in future I would not face problems with my circuits.


texts:
I am using an LTC1153 IC, with an IRLML6346 MOSFET.
I am supplying a 3.3V rail. Now, the output
is being fed to an arduino board and the supply works.
The Gate pin gives out about 7V (in conformance of the graph in the datasheet).

Thwe MOSFET is on and the current is supplied.
But, when I make a short circuit the Gate voltage is 2V and hence the MOSFET is still on.
The sense resistor is 1 Ohm and hence should be designed to shut out or turn off when the current is greater than 100mAmps(with the 100mV drop theory).
The Schematic is as shown below. -


texts: Winding Factor in Single Phase Induction Motors

texts:
How does one compute the winding factor in a Single Phase Induction Motor? I have checked Wikipedia, but it only states the relevant formulae for three-phase machines with no explanation of the theory.
Here's an excerpt from the book "Induction Motors" by Amin:

What exactly is M1? There is no previous mention of it anywhere in the book...is it an empirical coefficient of some sort, and where do I look it up?
According to this book the winding factor is defined as the square root of the ratio of the flux linkage of a distributed winding to that of a concentrated winding.
What surface do we use to compute the flux-linkage, or is it arbitrary? I also need to know the geometry of the current source to determine the magnetic field, what geometry do we assume?
Could someone explain concretely how do we obtain the value of the winding factor, preferably within the context of Capacitor Run SPIMs?
Sorry for my ignorance, I come from a pure physics background...


texts: Regarding the wiring of a relay, it seems to me it is customary to wire the hot side (L1, +) of power to the COM terminal, and not NO/NC terminals (which would be the outputs).  Is there a reason for this?  Is there any reference? Or does it just support logical sequential flow when reading a schematic wiring diagram?


texts:
I have an FPGA connected to an LMS6002D SDR from Lime micro. I also have an BladeRF board which I am using to help me verify the functionality.
I starting out with trying to create IQ data for BPSK modulation and I am not sure if I am understanding what format the data should be on when I send it to lms6002d.

Currently I have tried to encode binary 0 with I=500 and Q=0, while binary 1 as I=-500 and Q=0. So if I wanted to transmitt 0x2, I would send: (-500,0), (500,0)?

I have tried to verify with bladeRF (TX -> RX) and set up an IQ file with basically 0x0F0F like this (not sure if bladeRF does any processing of the data before sending):

500,0
500,0
500,0
500,0
-500,0
-500,0
-500,0
-500,0
500,0
...
..

When plotting the magnitude and angle of the received samples I get the following (close to what expected):

When trying the same in my FPGA and transmitting the same samples to lms6002d and receive with the bladeRF I get the following:

Can anyone tell based on the plot what might be wrong?  Am I generating the IQ data wrong?


texts:
I'm currently developing a device which require an ethernet switch on it (to provide Internet connection to a microprocessor and an iPad). One of the major goal is to make it very small.

I found an ethernet switch IC and a USB to Ethernet IC (both have MAC and PHY integrated), but I was wondering if it's necessary to put a magnetics between both of them or I just do some direct connection. Maybe an alternative with smallest passive component would be possible?

My microprocessor has an ethernet port on it, so I guess it would be the same connection as the USB to Ethernet IC?

Thank you all.


texts:
I was wondering if my display backlight could be driven by a voltage of 5 V. The datasheet (see image) says that it only needs a current of 60mA so could I put in 5 V and a 80 Ω resistor to make the brightness doable?

I tried with 16 V and a 330 Ω resistor and that made the backlight visible. The datasheet specifies 17 V minimum and it made me question things.


texts: Can somebody explain, please. How can I produce continuous signal from short one?


texts: Are these two OP-AMP circuits behaving different?

texts:
I am looking for DC biasing circuit for a bipolar square wave with frequency < 10 MHz.
I'd like to make a square wave with high 1.5-1.7 V and low (-1.5)-(-1.7) V into a square wave with high ~ 5 V and low ~ 0 V, such that midpoint is 2.5 V

And I've found two examples.

The First one is like:

And the second one is like:

As I have little knowledge about circuit, I am wondering if they are behaving same or not.

A signal in the first circuit is fed into (+), but in the second circuit, it is fed into (-). I think both circuit will output inverted waveform respect to each other. Is it right, or do I have a wrong understanding of circuits?


texts: Why are most RGB LED strips common anode instead of common cathode?


texts:
I've never used a bipolar ADC before, so I have a pretty easy question about it. I've skimmed over the datasheet and some references to Vref, but not enough to explain what my output codes are.

I'm looking at the ADS1282 ADC and I can set Vref (REFPx and REFNx pins) to essentially whatever I want within the limits of my supply.

For the purpose of understanding what happens, neglect any common mode input range, gain and other stuff. Lets say, I have an 8bit ADC +/- 2.5V bipolar supply with a Vref of 2V. If my input is 1V, what is my output ? If my input is -1V, what is my output ?

Would it be +128 for Vin=1 and -127 for Vin=-1 ?


texts: Explanation of 2nd order transfer function

texts:
I am reading about the 2nd order transfer function of a 2nd order system (like the mass-spring-damper system). I am constantly seeing the following form as the standard one:

\begin{equation}
H(s) = \frac{\omega_0^2}{s^2 + 2 \zeta \omega_0 s + \omega_0^2}
\end{equation}

But my questions are:

Why there are not zeros in this standard form? From what I am reading the general 2nd order transfer function can have zeros but in that form there are none and it is said to be the standard one.
Why there is no gain? I hardly found out sources that even mentioned the gain. Their standard form was:

\begin{equation}
H(s) = \frac{K \cdot \omega_0^2}{s^2 + 2 \zeta \omega_0 s + \omega_0^2}
\end{equation}

From what I understand the general form, the one that should be called standard, should be derived from the general form of the 2nd order differential equation:

\begin{equation}
a_{2}\frac{d^{2}y(t)}{dt^{2}}+a_{1}\frac{dy(t)}{dt}+a_{0}y(t)=b_{m}\frac{d^{m}x(t)}{dt^{m}}+b_{m-1}\frac{d^{m-1}x(t)}{dt^{n-1}}+...+b_{0}x(t)
\end{equation}

But from what I see it is derived from the not so general form:

\begin{equation}
\frac{d^{2}y(t)}{dt^{2}}+a_{1}\frac{dy(t)}{dt}+a_{0}y(t)=x(t)
\end{equation}

Why is that?

I have already read those questions (1),(2) and although they are not very similar I am mentioning them in case anyone see them as duplicates.


texts:
I am designing a circuit with a magnetic latching set-reset relay, and I would like to test the design in ngspice (open-source spice). I have downloaded the documentation but I see nothing about relays, so I wonder: how can I model this device?

I want to model a circuit that activates and deactivates itself automatically as a particular voltage varies. As input for the relay I only need a voltage (which will be categorized as "on", "hysteretical" or "off" by the relay, and as output naturally a short-circuit or open-circuit. I don't need much exactitude (such as relay impedance and the likes).


texts: I studied some documents which say that we need to protect digital inputs that come from some devices like NIDAQ in relation to ESD, short circuit or even overvoltage. But what about digital outputs? Some times we need to provide some digital signals to our circuit for turning on or off some switches, for example. Do we have to do something to protect the digital output?


texts: Replacing mic22705 buck converter with cheaper one

texts:
Since Microchip decided to increase their mic22705 price, my company decided to replace it with another synchronous buck converter. the current price we get for 20K units of mic22705 is 1.459$.
The board on which I will be doing the redesign uses Vin_Root voltage source which has the following product specifications for customers: Min = 3.3V, Typical: 5v, Max = 5.5v.
The mic22705 device is used 3 times in order to create the following voltages: 3.3V, 1.5V, 1.2V (pay attention to the power sequence order):

One solution was to use tps54719 as an alternative. the problem that I can't create Vout=3.3V from Vin=3.3V, which is a special case. (the simulation in https://webench.ti.com/ fails as a reason of exceeding duty cycle limit).
I heard some devices have bypass mode, this also can be an option in the solution I'm looking for, but I didn't dive into details\examples.
On the other hand, I'm not sure all our customers are really dependent on supplying 3.3V voltage input, and I'm not sure someone actually tried to supply 3.3V to mic22705 to see if it even works. but I have somehow to consider then option.
Questions:

is there a way to know if mic22705 can supply Vout=3.3V when Vin=3.3V even before trying to physically trying to make an ECO to the board and see it's output?
looking at mic22705 datasheet, I was confused by the following graph, which shows that for Vin = 3.3V, the output current is very small (around zero):

Does that that mean that for Vout=3.3V, Vin=3.3V I can be sure that even if one of our customers tried to supply "Vin=3.3V" and still our product worked fine for him, then surely the VPER_3P3 was consuming a very small current? does that mean I can replace only the first converter with other TI step down converter where it's Vin:3.3V-5.5V and it's able to create Vout=3.3V with lower amperage than mic22705 7A maximal output current?
Note: the idea is to use only two tps54719 devices and the third is another device which will be chosen according to what I mentioned above.
Update: the reason that the 3 converters were chosen to be mic22705, is that for the third voltage (that goes for the SoC), there is a high current consumption mode when the CPU is 100% consumed. and the designer wanted to choose a uniform DC2DC for the 3 voltages just because it's more comfort. but now, I see that Up to 7A for the three DCDC's might be too much. I'm trying to set a new maximal current limit by looking at the CPU Datasheet again. I summed all the currents in this table, and what I got is 6.260 [A]. can I set 6.3 [A] as the new maximal amperage delivery for the new 3 DCDC's?


texts: Is it safe to patch a capacitor with some aluminum housing exposed?

texts:
I was removing some capacitor adhesive and noticed that in doing so I ripped off some of the capacitor housing causing what seems to be the outer aluminum shell to be exposed.
The capacitor itself is still giving perfect readings.
What would be the effect of running this capacitor when patched with some electrical tape ?
Ideally it probably would be better to replace it completely, but I was wondering if such a patch would be considered ok ?


texts: Samd51 fatfs driver with sd card backend stuck in an infinite loop

texts:
I am trying to use the FatFs module in the Atmel start for my project with the samd51j19a chip. The clock is @ 120mhz and the sd card is wired according to the diagram on the PINMUX.  The program seems to be stuck in this loop @ /hpl/sdhc/hpl_sdhc.c:177:
/* Wait end of command */
    do {
        sr = hri_sdhc_read_EISTR_reg(hw);

        if (cmd & MCI_RESP_CRC) {
            if (sr
                & (SDHC_EISTR_CMDTEO | SDHC_EISTR_CMDEND | SDHC_EISTR_CMDIDX | SDHC_EISTR_DATTEO | SDHC_EISTR_DATEND
                   | SDHC_EISTR_ADMA)) {
                _mci_reset(hw);
                hri_sdhc_set_EISTR_reg(hw, SDHC_EISTR_MASK);
                return false;
            }
        } else {
            if (sr
                & (SDHC_EISTR_CMDTEO | SDHC_EISTR_CMDEND | SDHC_EISTR_CMDIDX | SDHC_EISTR_CMDCRC | SDHC_EISTR_DATCRC
                   | SDHC_EISTR_DATTEO | SDHC_EISTR_DATEND | SDHC_EISTR_ADMA)) {
                _mci_reset(hw);
                hri_sdhc_set_EISTR_reg(hw, SDHC_EISTR_MASK);
                return false;
            }
        }
    } while (!hri_sdhc_get_NISTR_CMDC_bit(hw));

the output of bt in gdb is as following:
(gdb) bt
#0  _mci_send_cmd_execute (hw=0x45000000, cmdr=0, cmd=cmd@entry=16384,
    arg=arg@entry=4541) at ../hri/hri_sdhc_d51.h:2980
#1  0x00001812 in _mci_sync_send_cmd (mci_dev=<optimized out>,
    cmd=cmd@entry=16384, arg=4541, arg@entry=0) at ../hpl/sdhc/hpl_sdhc.c:353
#2  0x000011e2 in mci_sync_send_cmd (mci=<optimized out>,
    cmd=cmd@entry=16384, arg=arg@entry=0) at ../hal/src/hal_mci_sync.c:115
#3  0x00000860 in sd_mmc_mci_card_init () at ../sd_mmc/sd_mmc.c:1127
#4  sd_mmc_check (slot=slot@entry=0 '\000') at ../sd_mmc/sd_mmc.c:1346
#5  0x00001e64 in sd_mmc_test_unit_ready (slot=<optimized out>)
    at ../diskio/sdmmc_diskio.c:50
#6  0x00001ec0 in disk_initialize (drv=drv@entry=0 '\000')
    at ../diskio/sdmmc_diskio.c:156
#7  0x00002782 in find_volume (rfs=rfs@entry=0x2000aca4,
    path=path@entry=0x2000ac94, wmode=wmode@entry=10 '\n')
    at ../fatfs/src/ff.c:2105
#8  0x000031ae in f_open (fp=fp@entry=0x2000ace8, path=<optimized out>,
    path@entry=0x54c4 "message.txt", mode=mode@entry=10 '\n')
    at ../fatfs/src/ff.c:2317
#9  0x00001df2 in main () at ../main.c:24

Here is my main file:
#include <atmel_start.h>
#include <fatfs/src/ff.h>
int main(void)
{
    /* Initializes MCU, drivers and middleware */
    atmel_start_init();
    PORT->Group[0].DIRSET.reg = PORT_PA16;
    PORT->Group[0].OUTTGL.reg = PORT_PA16;

    FATFS FatFs;
    FIL fil;        /* File object */
    BYTE buffer[4096] = "asdfggh";   /* File copy buffer */
    char line[100]; /* Line buffer */
    FRESULT fr;     /* FatFs return code */

    UINT br, bw;         /* File read/write count */
    fr = f_mount(&FatFs, "", 1);

    br = 8;

    printf("%d", fr);
    PORT->Group[0].OUTTGL.reg = PORT_PA16;

    fr = f_open(&fil, "message.txt", FA_WRITE | FA_CREATE_ALWAYS);

    f_write(&fil, buffer, br, &bw);
    f_close(&fil);

    while (1)
    {
    }
}

here is my current clock configuration:


texts: How does it work when multiple companies sell the same IC?

texts:
Very common ICs are sold by many manufacturers, for example let's say the TL07x range (which is vintage, but does demonstrate the case).

Inspecting datasheets of two manufacturers, TI and Diodes Inc, I find that they spec the same typical THD (0.003%) and noise (18nV / sqrt(Hz)).

What differentiates these devices? Is the silicon design simply licensed to both of these companies? Or do they purchase the device from the same fab house and simply stamp their individual brands on them?


texts: What technique can I use to focus a Bluetooth 4 transmission (or at least shield it)?

texts:
I'm actually trying to focus an iBeacon that uses Bluetooth 4.0 LE. These transmit in the ISM band from 2.4 to 2.485 GHz. Normally these things radiate in a spherical, or half spherical pattern, but I'd like to restrict the pattern as much as possible to a beam - think a flashlight. If the device was on the ceiling, and 'beaming' straight down, then for the most part only receivers directly under it would detect the signals, and devices meters to the side would not see the signal directly. [I realize there might be scattering, nothing to be done about that.]

I googled around today, found nothing on this searching for 'Bluetooth signal shaping' (and focusing). Then I thought of that old trick to improve WIFI reception - put the antenna in a Pringles can.

If there is no obvious solution to this, what materials might be used as shielding to construct a signal barrier?

EDIT: After posting this, a list of related posts on the side showed up, and I saw the word 'cantenna'. Searching on Bluetooth cantenna' resulted in a few videos of people making such things to get directional signals. I also read that Bluetooth is using the same frequency (more or less) of WIFI so those cantennas should work too. Also, Anindo Ghosh posted an answer, he recommends a wire mesh to restrict the signal - so I've got a bunch of things to try now.