texts: How to determine the DC operating point of a GaAs RF HEMT

texts:
I've been reading datasheets of RF GaAs HEMTs, such as this one:
ATF-33143

I understand the theory behind HEMTs, they are basically JFETs with higher electron mobility, thus, I thought that Schokley's equation to determine the DC drain current operation point of the transistor would also apply. The equation im refering to is this:

$$I_D=I_{DSS}\bigg( 1-\frac{V_{GS}}{V_P}\bigg)^2$$

Here is an excerpt of the ATF-33143 transistor datasheet:

There is something that doesnt make any sense to me, if you look at the specs it says that Idss is around 237 mA, and the pinch off voltage is around -0.5 V, so how is it possible that the quiescent bias current is 80 mA with Vgs=-0.5V? I would like to think that if -0.5V is the pinch off voltage, then in order to achieve an 80 mA current, Vgs would have to be between -0.5 and 0? using the before mentioned formula and solving for Vgs, I get that for an 80 mA current I would need a Vgs of -0.209V.

The transistor data sheet provides S-parameters for 3 different bias points ID=40 mA, 60 mA and 80 mA. So which formula should I use to calcule the drain current?

I'm aware that Idss is a poorly defined parameter that varies from transistor to transistor, however I would like to be able to analytically find the ball park figure for the DC operating point of the transistor.

Second question: If the pinch off voltage is -0.5V does it mean that in order to bias the transistor in Class A, then I would have to set Vgs to -0.25V? does that mean that the input signal cant be larger than 0.25V peak?


texts: How does a capactior reduce voltage ripples

texts:
The image below shows a very common use case of these capacitors in a full bridge rectifier.

Here is what I think:

The AC source acts as an independent voltage source, ie, it produces a fixed time-varying potential difference across its terminals irrespective of other components in the circuit. Since the voltage across the AC source is independent, the voltage source across the rectifier is also independent.

Now, according to Kirchoff's laws, the potential difference across the terminals of the rectifier must be equal to the poterntial difference across the capacitor. Applying the same law in the loop containing the rectifier and the load, the voltage across the rectifier is equal to the voltage across the load.

So according to me, the voltage across the load is governed only by the voltage produced by the rectifier and the capacitor does not do anything.
 Can anyone tell me where am I wrong?


texts: best way to regulate 3v3 from 25.2V (DC)

texts:
The circuit maximum voltage is around 25.2V so this is the supply im using, I wonder which one is the best way to get 3v3 with less components count and keeping it cost effective, space is a problem, smd components can be used.

PD: Its going to an ESP8266-12e, in datasheet maximum current is 170mA.


texts: I purchased LEDs with 100 ohm resistors for 12VDC  and 450 resistors for 5VDC.  I am replacing bulbs in my vehicle instrument cluster. When I test them at 12VDC they light up just fine, but my vehicle is pushing 13.4VDC and none of the bulbs light up. How do I adjust for the extra voltage?


texts: How do I convert 6V DC to 12V DC in a relatively small form factor.

texts:
I want to convert 6V DC from batteries to 12 V DC to drive 1m of LED strip (60 LEDs per meter) whilst using the 6 V to power
a microcontroller
4 TPIC5C569 Shift Register
1 SD Card
32 LEDs
Also, the application is worn on your body, so weight is an issue, and the reason why I want to use 4AAA batteries instead of 8 (Board space is another).

So essentially I'm looking for a circuit that is lighter and smaller than a 4 AAA battery pack, is mostly SMD, which can drive up to 1200mA of current.

On the other hand, if you do know some other way (non boost conversion) that will yield the required voltages (6,12,3.3) and currents (~200mA,1200mA,600mA), it'd help me greatly if you could also list it.


texts: How can I find current in this Ward-Leonard system?

texts: I was able to find only RPM in this question. How can I find the armature current?


texts: SMPS test circuit PWM controller not switching the MOSFET

texts:
Trying my fingers on a very old SMPS circuit (15+ years) section.
The open loop test circuit generates 25 kHz pulse train (12 V - 0 V) with 50% duty cycle as designed in the actual SMPS circuit. SK2996 has 3-4 V threshold voltage. I have kept the secondary open during the entire testing. Is a dummy load required for the flyback to work correctly m?

Q1.
On the first run, the circuit (secondary & all other sections detached) heats up the NTC (not shown) near the AC supply (230 V, 50 Hz) and the 317 V DC supply drops to almost 100 mV but none of the component malfunctioned. What possible must be happening? Something related to the pulse transformer itself?

Q2.
Next I remove the sense resistor to remove the MOSFET from circuit, but the 1.1 V at the gate (don't know how the voltage leaked as the MOSFET was cold tested OK) fried the UC3845B output totem pole section. Why? Is the PWM IC venerable once the MOSFET fails in actual SMPS circuit?

Q3. Any thumb rule how to safely and correctly trigger a MOSFET biased to 317 V DC in an SMPS circuit (search shows 12-16 V volt switching only) using UC3845B controller?

Open Loop Circuit

SMPS DUT SECTION


texts:
I have an incoming 100khz ir signal. (from a well designed optical front end).  I like to detect this signal even when it is very low. What is the best way to do this?
I am only interested in the amplitude of the signal. I do not worry about the phase shift. Detection time is somewhat important too. (ie I have perhaps 10 20 usec to decide, so a fast detection is requird)

So far I have considered:
Psd(lockin): too long to lock in and complex to implement
Bp filter: if I design a really narrow filter the amplitude doesn't change as much ( perhaps a design error?). I play with various options and current thinking is to use this option if I can fix the amplitude problem

Other options ?


texts:
G'day, I am currently experimenting with the an ATmega328P (on an Arduino, but programmed directly in C without the Arduino libraries)  and it's SPI bus for communication with no other devices straight away just watching the data fly pass on my oscilloscope.

But I'm currently having a problem where I can't transmit anything straight after initialising the SPI peripheral. At first I thought it might be a delay problem where I need to wait at least x us/ms between initialising the SPI peripheral and transmitting data but I can't find mention of it in the data sheet. But I am able to get the SPI bus to output data when I put SPDR inside an infinite while loop and get it to repeat the same character over and over again.

So my question is how can you force the micro controller to wait until the SPI bus is ready to transmit? Or have I made some other silly error?

int main(void)
{
    DDRB = (1 << DDB5) | (1 << DDB3) | (1 << DDB2) | (1 << DDB0);
    PORTB |= 1 << PORTB2;
    SPCR = (1 << SPE) | (1 << MSTR) | (1 << SPR1) | (1 << SPR0);

        PORTB &= ~(1 << PORTB2);
        // This doesn't work
        //SPDR = 'A';
        //while(!(SPSR & (1 << SPIF)));
        //_delay_ms(1);
        while(1) {
            // This works
            SPDR = 'A';
            while(!(SPSR & (1 <<  SPIF)));
            _delay_ms(1);
        }
}


texts: Why don't electrons in parallel battery circuits repel?

texts:
Here is a short snecdote, which will give a good explanation into my question.

I was in a science class, and we were doing a circuit with a very small filament light bulb, and some AAA batteries. I connected around 2 AAA batteries in parallel, as opposed to series, and I was promptly chastised, as apparently, in her words, I risked shorting her batteries. I have used batteries in parallel before, and I have never faced this issue.

Here is an example circuit, with the junctions I am confused about marked A, and B.
Now, from physics I learned that electrons have a negative charge, and that they repel, so why don't the electrons flowing from the cathodes of each cell repel when they meet ay A, and also later when they arrive at B?
I cannot find any explanation anywhere, and I was wondering if any of you amazingly smart people here could help me out with this issue.


texts: Altium: fetch nets of components from schematic alone with DelphiScript

texts:
I would like to automatically derate certain components in a schematic using DelphiScript.

For example, say we have a 5V and 12V net in our schematic and some 16V capacitors on each of those nets. In order to derate the capacitors to 50%, I need to select only those that are connected to the 12V net and replace them with, for example, 25V capacitors.

(Note that we can't accomplish this through the "Find Similar Objects..." dialog because that considers only the characteristics of the component itself, not its implementation details. As projects get larger with multiple sheets and interdependent boards, even grouping components by net isn't enough to keep this from becoming tedious and error-prone.)

The Connectivity example script comes close to providing a full solution. Unfortunately, the comments indicate that a physical document is required in order to determine components' nets.

Is there a way to fetch component nets from a schematic alone? I don't see why that would be impossible, as the nets are defined in the schematic and the rat's nest is generated from the same.


texts: What is considered ESD Sensitive and non-ESD Sensitive?

texts:
For example, if an integrated circuit has an HBM rating of 8 kV but is now embedded in a circuit board, which is now installed inside an equipment assembly, I would think the ESD susceptibility of the part is greatly lowered at the equipment level.

Per MIL-STD-1686, at the component level an ESDS component > 16 kV HBM is "non-ESDS." What ESD susceptibility test would I use to determine if the completed equipment containing ESDS parts is ESD hardened to > 16 kV HBM such that it’s considered non-ESDS?

From my current understanding, equipment/system level (e.g., IEC) ESD tests are used to determine the robustness of external surfaces and ports of equipment containing ESDS parts. However, its known that HBM and IEC waveforms are different, with the latter being more severe.

If I have an external port (e.g., USB port) with an IEC 61000-4-2 8 kV rating, can I consider that non-ESDS and not invoke ESD precautions by not putting an ESD label on the port?  Or should I still put an ESD symbol next to the external port? I’m asking this question because our company is reviewing ESD protocols and I want to ensure were only invoking ESD protocols and labeling ESDS parts/equipment/external ports when necessary.

Based on my understanding of ESD testing/susceptibility, an IEC 61000-4-2 8 kV rated USB port provides enough robustness such that the internal ESDS component its connected to is ESD protected during equipment level handling/operation. Therefore, adding an ESD label to the USB port is unnecessary. From a consumer electronics interpretation, Apple, Google, HP etc., do not label their USB or Ethernet ports. I'm sure they've hardened their external ports, such that the consumer doesn't need to use ESD protocols when handling their equipment.


texts: Is it viable to daisy chain power across motor drivers?

texts:
I'm working on a hobby project where I want to run two DC motorss using Adafruit DRV8871 motor drivers and a 7.2 NiMH battery. My idea is to daisy chain power from the first driver to the second, and then from that to an Arduino UNO for controller logic.
Here's my quick Fritzing sketch (the battery is a placeholder and I have not hooked up the signals yet):

So, is this an acceptable way to distribute power across the circuit?
If so, is it a good way to distribute power?


texts: I know that the ideal operation amplifier model is a single voltage controlled voltage source. My question is how to extend this ideal model, in a minimal way, to account for power supply rails (V- and V+).


texts: Polarity of feedback for a mosfet circuit

texts:
I came across this question in "fundamentals of microelectronics"
The objective is to find out the polarity of the feedback.
Could someone help me with this?

My approach to this question is as follows:

If we increase input current then the voltage at point x increases due to which the drain current of M1 increases causing a decrease in the Vout.This in turn decreases the drain current of M2 causing an decrease in the voltage at point x.Therefore the feedback is negative.
Is this approach correct?


texts: Relation between ADC register value & ADC accessing time?

texts:
I don't have any Electronics background.I am Software Engineer.

I want to know that is there any relation between accessing the ADC buffers with a time (T ) & the ADC buffer values.

I am working with Beaglebone white in Android platform .

I have one external ADC (ADC121C021CIMM - connected through Multiplexer MAX4617CUE (Interfaced with GPIO) ) & accessing through I2C via JNI code .

It seems that the value from ADC registers is inversely proportional to the Time between consecutive reads.

Simply if i try to continuously access the ADC buffers the value get increasing .

Please provide me some guidelines. I am totally a greenhorn .


texts: Help, How do I interface this screen with an arduino?

texts:
I have a very small LCD screen for my Arduino, it has a ribbon cable on it and I do not know how to connect it with an Arduino, it has a small piece of paper on it and that reads " OS096016PP08MB2B10 " not being stupid I did a google search on it and it came up with this as the data sheet, http://bit.ly/1M48HTo, it says it is a serial/parallel interface, and I cannot find a ribbon cable adapter for Arduino or Raspberry Pi,

All help is appreciated, thanks for even looking at this.


texts: Why do we use capacitors in parallel with DC motors?

texts:
Below is the circuit diagram of an L293D motor driver IC driving 2 12V DC motors.

What I don't understand is the use of the capacitors marked 104 in parallel with the motors.


texts:
I know that each task in FreeRTOS should have a vTaskDelay() to release CPU resource to other tasks periodically. However, when there is a very time-consuming function in a task, like read a large amount of data from a slow device, other lower priority tasks need to wait a long time. According to my understanding, even I have added delay after this 'heavy' function, lower priority tasks still need to wait a long time before vTaskDelay() is executed. How can other lower priority tasks have the opportunity to use CPU resource while the priority of this 'heavy' task keeps unchanged?

    void vTask()
   {
     while(1){
        func_heavy();      //this function take a lot of time
        vTaskDelay();
     }
   }


texts: Question about diode connected transistor (BJT) with current source

texts: I'm trying to find ΔV for this circuit, but I'm having a bit of trouble doing so.  I think the current on the right BJT will be n times greater than the left, but I'm not sure about that either.  It looks like a current mirroring circuit to generate a ref voltage that's stable with temperature, but I'm still unsure how to find ΔV.


texts:
I'm building a device to, among other things, measure a few voltages from different power supplies that are expected to be floating. Because the user might do silly things like connecting them in series to get a negative voltage, the measurement circuit should not connect any of them to its own supply ground.

The measurement logic itself uses a voltage-to-PWM converter, which measures the voltage above its own supply ground, so I need a low-current supply for this IC and an optocoupler that can float together with the measured value.

Do I have to build a chopper+transformer+rectifier+comparator+optocoupler circuit for this, or is there a simpler/cheaper topology that allows me to supply 5V/20mA (my pessimistic estimate) without connecting the ground reference?


texts: I am lost here, I was wondering what voltages do I have to include in the equation that is asked for both v1 and v2? and how do I do that?


texts: Why is the output to this 74181 ALU circuit always on?

texts:
I recently built an ALU circuit using the 74181 4 bit ALU. The circuit I built is below:

simulate this circuit – Schematic created using CircuitLab

Please note that the pinout in the datasheet(linked below) is not the same as the pinout in the schematic above. (All pins are shown, but their relative positions aren't the same in the real chip) I am using a 5V 1A power source(measured voltage is 5.08V). No matter what the switches are set to, the output leds are always on. I figure that this has something to do with the way the inputs or outputs are set up. What is(or are) the problem(s) with the circuit. If you need any further details please ask. This is the DM74181 datasheet. (Although the datasheet is for the DM5481 they seem the same).


texts:
I'm curious if anyone can validate the efficiency of a multilevel inverter. I've been thinking about them as a better solution for PV conversion. They seem to have many advantages, but when I look at it, a single phase output can seemingly only draw power from, on average, half of the panels at a time.

I've seen this circuit both with and without caps across each individual source. I just can't see how this can do better than 50% efficiency especially without the caps.

Edit: I keep looking... I've found a ton of these that are grid tie. Lets say you have 6 panels that have an output voltage (after MPPT and DC-DC boost phases) of 30 V and each can provide 5 amps. So, I've got a peak voltage of 180V which gives me ~120Vrms. Now, the total available power from the panels is 180V*5A = 900W. But, my output power is 120V*5A = 600W. I feel like I'm missing something critical. Someone please tell me exactly how I'm being an idiot.


texts: Converting pre-lit Christmas tree with incandescent mini-lights to use LEDs

texts:
This might be a dumb question, but has anyone been able to successfully convert a built-in incandescent mini-light string to use LEDs?  I have a few of these pre-lit burgundy-colored tinsel Christmas trees, which I like because not only does it eliminate the need to run a separate light string, the wire and sockets of the string blend in with the color of the tree, but obviously I'd prefer to substitute the lights themselves with LEDs if possible.

https://www.hayneedle.com/product/burgundy-tinsel-pre-lit-medium-christmas-tree-4-ft.cfm

https://www.hayneedle.com/product/burgundy-tinsel-pre-lit-medium-christmas-tree-75-ft.cfm?ltype=child&tid=GERS483-1

Again I'd like to keep the actual wire and sockets, but from what I understand, LED mini-lights rely on impedances in their special strings since the bulbs themselves are little more than the LED elements, so I'm curious if it would be safe to, say, splicing in the resistor canisters from off-the-shelf LED light strings or if doing that carries notable risks like starting a fire that could burn down my office building.


texts: Battery Powered System and Input Capacitance

texts:
I have a battery powered system in which the battery is connected to a buck/boost converter to derive 3.3V from two or three AA batteries. The regulator I'm using is a TI TPS63050, and it has a power good output signal, which behaves as follows according to the datasheet:

  The power good goes high impedance once the output is above 95% of the
  nominal voltage, and is driven low once the output voltage falls below
  typically 90% of the nominal voltage.

I'm currently using an ample bench-top power supply (with the current limit set at 1A, well above what I need) to evaluate the basic operation of the power front-end.

What I'm seeing is that, when my system (a wifi-connected ESP32-based processing subsystem) starts running I see the power good signal drop out briefly occasionally on an oscilloscope. I have a little capacitance 10uF in parallel with 0.1uF on the input to the TPS63050, and 10 uF in parallel with 10uF right at the output of the TPS63050 as well.

Is that just way too little? Looking at the input power to the scope there are some dips on the input power corresponding to dips in the output power, and correlated with the power good signal dropouts. I'm wondering if I need to put a significant bulk capacitor on the input side of the TPS3050. I don't really understand why the load I'm dealing with (a few hundred milliamps at most) would cause the bench top power supply to break a sweat instead of holding the input voltage rock-steady.

I am running power to the board through a decent length (~3 feet) of alligator-clip banana-plug cable and then a short length of Dupont-style jumper wires (~8 inches) to mate to pin headers on the board under test.

Any ideas?


texts:
A quick question: If I have a potential divider with two 10kΩ resistors, is the noise that you would measure between the two resistors simply the the Johnson noise of a 20kΩ resistor?

On a similar note, if I have two 10kΩ resistors joined together in series, and measure the noise across just one of them, i.e. the second resistor is unconnected at one end, is the noise just the Johnson noise from a single 10kΩ resistor, or does the floating 10kΩ resistor add any Johnson noise?  (I suspect it would somehow act as an antenna or something.)


texts: Verilog Implementation error DFFs and Gates

texts:
I am a beginner in verilog and came across this question-

Given the finite state machine circuit as shown, assume that the D flip-flops are initially reset to zero before the machine begins.

Build this circuit.

My Code is -

module top_module (
input clk,
input x,
output z
);
reg q,q1,q2;
always @(posedge clk)
    begin

        q<= q^x;
        q1<= ~q1 && x;
        q2<= ~q2 || x;
        z=~(q | q1 | q2);
    end
 endmodule

Suggest me where i am going wrong!


texts: Battery pack solution for a 5V 500mA project

texts:
My project contains:

Raspberry Pi Zero W
Arduino ProMicro
10 5V RGB LEDs
I2S amp that drives a 4Ω 3W speaker

Currently I am powering it from a 10000mAh USB power bank. But in order to avoid brutal powerdown, I need a "smart" battery solution where the battery level and charging/discharging status could be monitored and user informed about it.

My current measurements show that at rest it consumes 220mA, max current is about 800mA, and normal use current is about 500mA.

I'd like it to be able to live from full charge something around 24h. During that time, it would be actively used for about 2h, while the rest of the time it would be in "resting" mode, consuming no more than 220mA. So, I figure I need 2*500+22*220=5840mAh (at 5V) battery solution.

I have checked for the necessary circuitry needed to monitor the battery charging (Sparkfun Battery Babysitter - LiPo Battery Manager) and a voltage regulator. But I am puzzled about the Li-Po element - for a 3.7V Li-Po output voltage, stepped-up to 5V that would mean I need 5840/3.7*5=7892mAh (if my calculation is correct).

So, do 8000mAh Li-Po elements exist? If they do, it seems they are extremely rare.


texts: One of the ESC's on my quadcopter is missing a component. I am unsure what this component does or where to find a new part. Is it a sort of resistor?? What size? it features no markings that I can see. I have attached images of the working esc and of the esc with the missing part. (See arrows)


texts: is it possible linear response photodiode amplifier using 2n3819

texts:
This is a typical jfet circuit to amplify the photodiode signal.
Is this simply the photovoltaic voltage generated by the photodiode?
My understanding is this is highly non-linear since the voltage increases across the diode, with increasing light level.
At very low light levels it is possible the diode remains only slightly more than zero bias.
I have used the AD743JNZ with no problems previously. It is now a rare and expensive item. 2 orders from ebay turned out to be fakes. Digikey, Farnell and RSonline all now have minimum order charges.
For an AC audio modulated light signal up to 3kHz, I have been trying a discrete jfet circuit. I am sure this is not a transimpedance configuration as in the opamp implementation which maintains zero bias across the diode via the large feedback resistor.
Is there a simple variation on this circuit that can do this with very low noise, very high sensitivity for only the AC signal required?


texts:
So long story short I'm attempting to build a charger for batteries using a DC motor. The batteries I'm planning on charging are old smartphone batteries at 3.7V and 1000mAh. The DC motor that I am currently looking at can be found here. From what I've been able to puzzle out I'll probably need to rectify the output of the motor and soften the wave with a capacitor. Beyond that, I've heard that I probably will want to use a voltage regulator and have a CC,CV circuit. Working off of this post I found a trickle charger that would lead me to this:

simulate this circuit – Schematic created using CircuitLab

I would like to use something other than a trickle charger, as a trickle charger will probably take too long. If anyone has a better circuit I'd love to see it. Additionally, if anyone could walk me through this so I can evaluate the values of the resistors, caps, and diodes. My first instinct on the diodes is to use schottky's so I don't lose as much voltage and to rate them at about 3A. As for the rest, any help would be appreciated. Additionally, any pointers on modelling the behavior of this circuit would be highly appreciated. Magically I didn't find a DC motor in spice, so I don't know.


texts: Name or part for the kill switch on a model rocket launcher?

texts:
Is there a name or a part-number for the type of kill switch used on a model rocket launcher ? The switch is closed by putting the key (basically a metal pin) into the hole.

Is there a module I could buy, or if not does anyone have suggestions on how to build one?

This would be for low voltage application.


texts: Finding the resistance of a resistor without multimeter

texts:
So this is a trivial but frustrating issue I’ve come across. I have two 5 band resistors and I am having a hard time differentiating the tolerance band.

I don’t have a multimeter on me and I don’t know if these are 1k (Brown black black brown brown) or 110ohms (Brown brown black black brown). Am I being completely oblivious to something?

Edit: I do know that the tolerance band is supposed to be at the end with the largest band spacing, but it looks equidistant to me.


texts: Isolating A Noisy Component In A Circuit

texts:
I've been working on a project the past couple months or so and I am incorporating an lcd touch screen as an interface for it.  The device is a small digital synthesizer.  The problem I am having is that when I have the screen connected to the circuit, I notice that it produces a great deal of electrical noise on the power rail.  This noise is bleeding into the audio amplifier section of my circuit and making its way into the output audio of the device.  I have filtering on each individual block of my circuit and that has been good up to this point, but it doesn't seem to help this at all.  I'm not sure how to go about solving this.  The only thing I can think of is that I need to somehow isolate either the screen from the rest of the circuit or isolate the block that handles the audio signal.  I'm not exactly sure how to go about this though.

The noise itself is a mix of a lower frequency hum and some high hiss.  I assume this is caused by both the refresh rate of the screen plus the multiplexing of the LEDs.  I don't have a schematic for the actual circuitry of the LCD screen as the manufacturer doesn't seem to provide one

I have some screenshots from my scope for the 5v rail with both the screen disconnected

and also connected to the circuit.

Here is a simplified schematic of the circuit I'm using.  I know the power supply section of it could be better, but I'm still learning.  Any help would be appreciated! :D


texts: Remove bridge offset before ICF amplifier or at FB pin?

texts:
I'm making project where I would like to read from stain gauge sensor. It will use only one 1k ohm (or 350 ohm) strain gauge and 3 dummy resistors to complete bridge (1k or 348 ohm). I'd lik to feed signal from bridge to A8237 ICF amplifier and I'd like to know what is better way of remiving initial bridge offset Like there:
First Way

Or:

What I mean by sesnod way is that I'll connect DAC output with RA to one of bridge signals and adjust voltage.

Which one is better?


texts: Can a 30 watt (RMS) speaker work with a 5V 2A power supply?

texts:
I am thinking of using a speaker with Raspberry Pi 3b+ which has a 5V output pin.

Speaker data:

Power rating (RMS) 30 Watts
Power rating (max) 60 Watts
Impedance 8 ohms

Will this speaker will work with 5V and 2A?

This is the speaker:

Peerless by Tymphany TC9FD18-08 3-1/2" Full Range Paper Cone Woofer


texts: Controlling low DC voltage with high AC voltage

texts:
I replaced my existing manual roller blind switches with Wi-Fi-enabled touch ones and I'm facing an issue with properly fitting them in my setup.

The manual roller blind switches operated on 16 VDC supplied by Somfy 2 AC Motor Controller installed at the distribution board in my hallway. The new touch switches, however, output 230 VAC and I'm trying to figure out how to proceed.

This is how the initial configuration looked like:

The 16 VDC control signals were transmitted over telecommunications cables (4 x 0.8 mm diameter lines each). I'm guessing it would not be safe to use these cables to transmit 230 VAC instead? Even if it was only to control remote relays and not power any real load, as pictured below?

Another option I see is to place the relays in the junction boxes like this:

But I think that fitting them in there would present a challenge due to very limited space.

How should I go about this? Let me add that the touch switch manufacturer does not offer any low voltage-rated ones, nor could I find any alternatives online. Also, at this point, I'm unable to lay any additional wires between the distribution board and the junction boxes.

If I were to use relays as in the above diagrams, what type / model should I choose?


texts: Electric flux density independent of bound charge?

texts:
The electric flux density is defined as $$\mathbf{D} = \epsilon_0 \mathbf{E} + \mathbf{P}$$ where P is the polarization vector of the material. As I understand it, the net electric field includes the polarization component, and we define D in such a way that it is independent of the material or the bound charge. But if D is truly independent of the bound charge, then why does it change across boundaries of different materials? In particular, the tangential component changes from one material to another: $$\frac{D_{t1}}{\epsilon_1} = \frac{D_{t2}}{\epsilon_2}$$

I am also confused as to why P is added in the equation. It seems to me that if D is to be independent of P, then it should be subtracted instead.


texts: Compute loss/inch for (differential) T-line from s-parameters?

texts:
I have the 4-port s-parameters of 2 PCB boards, where each board consists of a differential transmission-line with SMA connectors on either end.

The only difference between the boards is their trace length is different.

Can I accurately compute the insertion loss of the PCB trace in dB/inch? If so, how?


texts:
I'm designing a low-frequency op. amp. circuit that operates from a single 10V supply.  I'm using a TLE2426 "rail-splitter" to generate a virtual ground, 5V above earth ground, which is used as a reference for the op. amps.  Normally, if I had bipolar +5V and -5V supplies, I'd decouple the high and low inputs of the op. amp. to the earth ground.  With a single-supply op. amp. design, I've heard to decouple straight from the high supply to the low supply.  So, I have the following possibilities:

2 capacitors: op. amp. high to virtual ground, op. amp. low to virtual ground
1 capacitor: op. amp. high to op. amp. low
3 capacitors: both of the previous options

In theory, the first option creates an equivalent of the second option with half the capacitance, so long as the trace impedances are low.  I was hoping for a discussion on the pros/cons and if there is a definite recommended approach.


texts: Why do I get a huge batch of data at once instead of small 4 bytes pieces one after the other?

texts:
I have written a program which sends  4 bytes and a terminator \n byte, over and over in an endless loop. The full code is shown below.
To transfer data I use an FTDI cable - the datasheet is shown below.
I am connecting my EFR32FG14 controller and in MATLAB I am defining the port as shown below.
The communication is done using the TX RX GND shown in the diagram below.
We have LF which is \n and I defined a callback function to see the 4 byte data  each time MATLAB sees \n. The MATLAB callback function is shown below.
function callbackSerial(ser,~)
val=fgets(ser);
dec2hex(uint8(val))
end

But MATLAB is not reacting to \n at all. I don't get a live stream of small bits, instead I get a large delay and a huge block of data on the terminal as shown below.
Where did I go wrong?
https://www.mouser.co.il/datasheet/2/163/DS_C232HD_UART_CABLE-4313.pdf
    sObject=serial('COM4','BaudRate',115200,'TimeOut',10,'Terminator','LF')
sObject.BytesAvailableFcn={@callbackSerial};
fopen(sObject)

*******************************
#include "em_device.h"
#include "em_cmu.h"
#include "em_gpio.h"
#include "em_usart.h"
#include "em_chip.h"
#include <stdint.h>
#include <stdbool.h>
#include "em_emu.h"
#include "bsp.h"
#include "bsp_trace.h"

uint8_t received_flag=0;//
// Receive data buffer
uint8_t buffer;
uint8_t tx_buffer=0x6F;
uint8_t tx_buffer_new=0x06;

void USART0_RX_IRQHandler(void)
{
    received_flag=1;
  // Get the character just received
  buffer = USART0->RXDATA;

  switch (buffer)
      {
        case 'a':

            tx_buffer_new=0x4F;
        break;

        case 'b':
            tx_buffer_new=0x62;
        break;

        case 'c':
                    tx_buffer_new=0x63;
         break;

        default:

        break;

      }//end switch
  // Clear the requesting interrupt before exiting the handler
  USART_IntClear(USART0, USART_IF_RXDATAV);
}

int main(void)
{
  uint32_t i;

  // Chip errata
  CHIP_Init();
  CMU_ClockEnable(cmuClock_GPIO, true);
  CMU_ClockEnable(cmuClock_USART0, true);

  //EFR32fg14 LOC2 page 157 data sheet TX P0
  GPIO_PinModeSet(gpioPortA,2, gpioModePushPull, 1);

//EFR32fg14 LOC2 page 157 data sheet RX P2
  GPIO_PinModeSet(gpioPortA,3, gpioModeInput, 0);

  GPIO_PinModeSet(gpioPortA, 5, gpioModePushPull, 1);

  // Default asynchronous initializer (115.2 Kbps, 8N1, no flow control)
  USART_InitAsync_TypeDef init = USART_INITASYNC_DEFAULT;

  // Configure and enable USART0
  USART_InitAsync(USART0, &init);
  //datasheet page 157 location2  rx portA pin3(P2) ,tx port A pin2(P0)
  USART0->ROUTELOC0 = USART_ROUTELOC0_RXLOC_LOC2 | USART_ROUTELOC0_TXLOC_LOC2;
  USART0->ROUTEPEN |= USART_ROUTEPEN_TXPEN | USART_ROUTEPEN_RXPEN;

  // Enable NVIC USART sources
  NVIC_ClearPendingIRQ(USART0_RX_IRQn);
  NVIC_EnableIRQ(USART0_RX_IRQn);
  //enabling TX interrupt made problems
  //NVIC_ClearPendingIRQ(USART0_TX_IRQn);
  //NVIC_EnableIRQ(USART0_TX_IRQn);

  while (1)
  {

      if (received_flag==1)
      {
          USART_Tx(USART0,0x2F);
          USART_Tx(USART0,tx_buffer_new);
          USART_Tx(USART0,0x8F);
          USART_Tx(USART0,0x3F);
          USART_Tx(USART0,'\n');
          tx_buffer=tx_buffer_new;
          received_flag=0;
      }
      else
      {
                  USART_Tx(USART0,0x2F);
                  USART_Tx(USART0,tx_buffer_new);
                  USART_Tx(USART0,0x8F);
                  USART_Tx(USART0,0x3F);
                  USART_Tx(USART0,'\n');

      }
      for(i=0;i<10000;i++)
      {
           GPIO_PinOutSet(gpioPortA,5);
           GPIO_PinOutClear(gpioPortA,5);
       }

    // Enable receive data valid interrupt
    USART_IntEnable(USART0, USART_IEN_RXDATAV);

  }
}


texts: I have defined Plated through holes on my PCB design.But somehow my pcb manufacturer has drilled it as non plated through hole and PCB has arrived.Now I need a suggestion to convert this non plated through hole to plated through hole using wire /solder pin.


texts: Connecting GPU chips in order to create more powerful graphic card

texts: I had thoughts about GPU and I came up with an idea. Why not putting more than one GPU chips in order to create a powerful graphic card? Is it possible with ordinary GPU chips or one need custom hardware? If it's possible how to interconnect this chips on the PCB? Just theoretical question.


texts: How does gearing affect power generated by a permanent magnet DC motor?

texts:
I am currently working on a project to harvest electrical energy from a rowing machine. I am trying to make use of gearing ratios to adjust the resistance level offered by the system, and the impact it will have on the generated power. I plan to connect the flywheel of the rowing machine to the shaft of a PMDC motor by chain or belt.

I am looking at an RPM range between approximately 400 and 800 for the flywheel. If the radius of the sprocket attached to my flywheel was lets say 0.3m, and the radius of the sprocket attached to the motor was a smaller size, say 0.1m, I would expect a greater number of RPM in the motor shaft. However, what would I expect in terms of the power generated by it, and the resistance against the mechanical force applied by the rower?

Also, is there a maximum counter-torque I would expect from a given motor, for example if the gearing ratio was adjusted so that more torque was being applied to the motor than it could provide counter-torque? I've noticed that motors are rated by their motor torque. Is the maximum counter torque equal to this value? What would happen if it was exceeded? Would no additional power be generated?

Sorry if the question is a little vague/factually inaccurate i can try to add any additional information needed. This is all very theoretical at the minute, just trying to gain some understanding.


texts:
I want to detect with a microcontroller if a fuse has blown. The circuit with the fuse is 12V when on (it is not always on, so I need to distinguish between a blown fuse and the circuit not running).
The microcontroller can only handle max. 3.3V.

I thought about using two optocouplers like this:

Is there a better solution you would use?


texts:
I have one confusion in the Millman'S Integrated Electronics 2E
in the exponential decaying graph its saying that P'(x) is the excess hole concentration or the injected concentration

  but in the next page in one example it taking excess hole density as P(X) but not P'(x) Why it is so ? what i am  missing? can anyone help Please?


texts: Why does this circuit speedup the switching time and reduce losses?

texts:
I am a little confused as to how this circuit works:

According to this website its function is to speedup charge time of the MOSFET as well as reduce losses. How does D1 and Q2 actually work to make this happen? If it's just to prevent the MOSFET from discharging, wouldn't only having D1 work?

Thanks!


texts: Why phase noise is critical in communication systems

texts:
I see expensive OCXO and TCXO oscillator on market that used on Milcom and Satcom transceiver.
I'm wondering on what application phase noise of more than -150dBc/Hz in 10KHz is critical and how such a high performance can help the communication system vs cheaper oscillators with -120dBc/Hz in 10KHz

Note: I'm not asking for the effect of phase noise on communication system. I'm asking for what application the phase noise are so important that they should use TCXO or OCXO oscilator with such a high performance.


texts: Is there any research for chemical/structural method to prevent observing beneath chip packaging?

texts:
I want to prevent others from reverse-engineering the on-die ROM, using X-ray, microscope, etc..

I think it's best to inject some substance between chip and packag and when the chip package is tempered or the radiation comes through the chip, that substance explodes or do someways to destroy the chip(at least ROM structure).

Is there any research doing this kind of things to prevent reverse-engineering of chip or at least, on-die ROM structure?


texts: What are possible solutions for changing DC motor rotate direction controlled by microcontroller? I know that H-bridge is one possible solution, but i want to use 2 pins for control only.


texts:
We're experimenting with using a WiFi module as a battery driven beacon or RFID tag. The cheapest module out there with plenty of documentation (thank you Adafruit) is the Texas Instruments CC3000.

The big problem is the power consumption - 190mA on transmit is very high for a battery driven product - and the demand is for 1 year+ battery life transmitting maybe once every 10-15 minutes. The range is over 150m x 150m with only enough data sent to indicate presence - ie: a beacon.

My question is - how quickly can the CC3000 wake up, transmit and shutdown? The indications are that it takes 60ms to initialise from sleep. Connecting to the Access Point is generally a long drawn out process, at least it is on a Windows machine. I assume that once connected, you could send a broadcast rather than waiting 1000s of milliseconds for DHCP to finish but I don't know if the CC3000 gives you that control.

A posting on TI's forums suggested that it would take 6 seconds to connect to an AP. At 200mA, 4 times an hour you'd need an 11Ah battery for a year; which isn't what I'd call an RFID solution!

(My personal feeling is that this path isn't a reasonable one - if you have to be at 2.4Ghz then there are BLE modules (Nordic Semi) that are more suited but the boss likes WiFi and its range (+18dBm). Anyone have any experience with WiFi in this scenario?)


texts:
I generated a 29 kHz sine wave using an STM32 DAC periphal. The sine wave has 2.96 V output, but I need to make it at least 10-12 V. I tried using TL084, OP07CP, AD620 but the TL084 and OP07 don't amplify it. The AD620 makes the output voltage around 4.5V but it becomes square wave (gain was supposed to be 4). Supply voltages are +15V and -15V.
I also tried some transistor circuit designs but the transistor makes my signal square.
How can I amplify my 29 kHz signal?

simulate this circuit – Schematic created using CircuitLab


texts:
I have to simulate a SRAM and I already replicated the circuit in Proteus. Still, I'm unsure where to start. I haven't found any table to see how to assign data and then how to read it.

Could anyone please tell me how this SRAM is working? Am I missing something?

Thanks in advance.


texts: Should I look for Aluminum or plastic enclosure for UPS

texts: I am on the process of material selection for the UPS I am prototyping. My plan is to manufacture a product that should finally go to the market.  I am relatively new to the manufacturing and I would like to get some advice on the selection of the right enclosure material for electronics equipment like UPS.  Should I look for Aluminum or plastic enclosure?  Please advise me from both economic and technical sides


texts: Implementation details of a home microcontroller network

texts:
I'm currently building a house, and thinking of adding some home automation features. I was thinking of putting one or two microcontrollers in each room (housed in a junction box), and connecting them to a central hub using a CAN network. I know how to do the interesting stuff like programming the microcontrollers and making the necessary circuitry, but there are some more mundane things I don't know how to best do:

The first issue is how to power the microcontrollers. I don't want to deal with batteries. Having a separate AC/DC converter for each microcontroller seems inefficient. Since I'm not using ethernet, power over ethernet seems inconvenient. So I'm thinking of having a central DC power supply (or maybe one for each floor), and then running wires from it to each microcontroller. Does this sound like a good option?
I don't know anything about power supplies, in terms of what different kinds are available. Are there points I should keep in mind when selecting one?
I need to run the CAN bus and power to each microcontroller. Is there a standard cable for doing this? (Something that has two pairs of wires with appropriate shielding and twisting, I suppose.) It'd be nice if I could just have a single cable going to each microcontroller.
Some of the sensors might be several feet away from the microcontrollers they connect to, so I'll need to run some wires in the wall between them. Can I just use whatever cable I have for this, or are there any special considerations that need to be made? (Sorry if this is too general, but any advice would be appreciated!)


texts:
I use Rasperry Pi / Arduino as power source (5V,3.3V) and for input/output (GPIO, Arduino headers). I reached a point when I realized, that what's in my mind needs diodes.

I'm building a morse transmitter/reciever trainer, and there will be two options to drive a piezo:
1. when the program outputs morse code,
2. when I press a button and the signal is going to the Piezo and to a GPIO input.
The two lines needs to have diodes so when one line is working it can't get through the other

I read that Raspberry 5V current is about 200-300mA. Here I read the Arduino 5V current is about 400 mA.

In the shop there are plenty possibilities. I found one, BAV21. I can't make much out from it's page, but they wrote two data: 200V and 600mA. My logic is: 200V bigger than 5V, 600mA is bigger than 400mA. It should be OK.

Is it good for what I mean to do? Is it too low, too much? Is there more suiting diode? How to chose a diode for breadboarding?

UPDATE 1:

This is what I have in mind. This is only using the Raspberry Pi. I wrote a program in Java ME 8, which can recieve (GPIO 17) and send (GPIO 22) morse signal.

simulate this circuit – Schematic created using CircuitLab

The best would be if I could drive the piezo from the 5V with the GPIO22. How could I do that? With an NPN transistor perhaps?

(Another thread about part of this circuit is going on here.)


texts:
I am reading the STM32F429II data sheet and looking at page 84, which shows the memory mapping. The chip has 2MB of internal flash memory, but the data sheet is general for all STM32F427xx/STM32F429xx chips.

I can see that internal flash memory range is from 0x0800 0000 to 0x081FF FFFF, which gives a maximum of 0x1FF FFFF = 2MB.

It also says that the STM32F4 devices with 2MB of internal flash has its memory divided in two banks of 1 MB each. This means it is possible to execute code from one bank, while at the same time erase/read/write from the other without halting the code execution (if I have understood it correctly).

On the specific chip I mentioned, is it safe to assume that the start address of bank 2 (program executes by default on bank1 I assume) is 0x100 0000? Where can I find this information? I have not seen it in the data sheet or the reference manual.


texts:
So a friend and I were talking about schematics at work and how we can better communicate among us and our co-workers. I know Kortuk had asked a question previously that was similar, but that question was more about how to make the schematics.

Instead, I'm now asking if anyone knows a good way to collaborate on schematics that are already complete. Kind of like the "Google Docs for Schematics" I talked about in response to Kortuk's question. I have a bunch of schematics in pdf form that I want to be able to mark up and show to someone with a link as opposed to sending it to them. I also want the content to be secure and probably on an internal server.

I think what I really want is a wiki plugin that would allow me to do something like this. Has anyone heard of any program that could achieve something like this?

FYI, I've seen software such as a.nnotate, but don't know if I can swing the price they ask (to keep it behind my firewall). So I'd appreciate open source but am willing to pay something.


texts: Calculate the voltage and the current of a ideal diode

texts:
I need to calculate the circuit below. (The used diode in the schematics is not the same from the task we have to solve. In our task we work with a ideal diode.)

simulate this circuit – Schematic created using CircuitLab

In school we learned, that a ideal diode could be substituted with a normal voltage source with the forward voltage of the diode (in our case 0.7V). Now I am not sure how to solve this task and how would a general approach on solving such problems look like?

According to the solution, the voltage meter should show V = 3.975V and I = 198.75uA


texts: Can a fluorescent light electronic ballast fail and still supply voltage?

texts:
I am trying to debug a failed fluorescent light fixture. T8, 1x36W. I have checked the tube (vs. both a new one and a known working one), and this is not the problem. So I thought it must be the electronic ballast ("preheating start" type). What is confusing me though is that there is power both going into and out of the ballast (and also reaching the actual clamps for the tube light).
So my question is: is it possible that the ballast is broken, but that there is still power coming out of it? By "power" I mean there is enough voltage across the output terminals of the ballast to light up a phase tester screwdriver.
Thanks!
PS. This setup does not have a separate starter.


texts:
from the reference manual we have the formula shown bellow.
We need to divide HFPERCLK which is 2MHz by 20 to get 100Khz clk.
From I2C_CTRL we have CLHR bitfield but as you can see bellow its not defining exactly N_low and N_high but the ratio of between them.
how do i define them exactly?
Thanks.


texts:
Question: A BJT for which \$BV_{CBO}\$ is 30 V is connected as shown in the figure below. What voltages would you measure on the collector, base and emitter?

simulate this circuit – Schematic created using CircuitLab

Answer: \$V_B = 13.3 V\$

\$V_C = 43.3 V\$

\$V_E = 12.6 V\$

I have no idea how to proceed with this question. How is the breakdown voltage related to the terminal voltages?


texts: Limited blind via pairs - Use for power or for signal?

texts:
I'm working on a PCB with 0.4mm WLCSP's and 0201 discretes. It will have components on both sides. The routing is very tight; I can't use a simple plated through hole ("PTH") design.

I'd like to avoid the costs of sequential laminations. It looks like I can get away with six layers with a single-lamination design. This only gives me one set of blind vias and no buried vias. I've figured out fanouts that should allow for a mechanical drill (6-mil drill; 12-mil ring; filled via-in-pad).

Now I have to decide how to use my stackup. The board has RF at 2.4GHz and 3.5GHz. The transceivers will be very close to their respective antennas.

If I place ground and power planes on L2 and L5, I can use the blind vias for power, as shown:

In this case, one of the power connections will be a blind via and the other will be a PTH. All of my signal routing will have to be carried by PTH's. There are decoupling benefits when using blind vias for power connections. This layout gives me a close reference plane to the RF on layer #1. It also shields the signal layers L3 and L4.

Or, if I put ground/power on L3 and L4, I can use the blind vias for signal routing:

In this case, the routing will be much easier. However, I lose any low-inductance decoupling benefits of the blind vias. Also, my RF on layer #1 is now farther from a reference plane (I'd remove copper on L2 to make L3 the reference...)

The first case strikes me as better, but the second case will significantly simplify my routing.

Is there an obvious better choice here?  What are the primary considerations?


texts: Op-Amp as comparator for driving relay stops working after short time

texts:
Ok I have an Op-Amp as a comparator,

Its the TCA0372...  whole amp it can source, not needed just nice.

and I have a relay,

http://www.mouser.com/ds/2/315/jw-catalog-1075968.pdf

Its driven by 12v.

So with flyback diode and all I have it set up as a regular Op-Amp comparator to the coil of the relay.  This worked great everytime without fail when I did this on a bread board.  I put this onto a PCB board I made and had fabricated and populated and now it works for a few seconds and never works again untill power cycling and giving it time.  (almost sounds like overheating)

The Op-amp V+ is 12v and V- in Ground.  Also I know an Op-Amp is not always best to use as a comparator but I had it laying around and verified on bread board it would work.

I check the + input the problem is not there as it gets the full 3.3v im using to drive it.  Also the Vref is set with a voltage divider and iv verified its at 1.6v.  I power on my board and this whole thing works a time or two and then it never works again.  The output is around 0.43v.  Its almost as if its over heating and needs time powered off to recover.  however this Op-Amp can source a while amp and with the internal resistance of the relay coil it should draw no more then 44mA from the output of the Op-Amp.

Anyone know what could be going on.  Iv tried the reference voltage extremely low and also tried pull up and pull down resisters on the output.


texts:
I see that the TPS61093 UVLO is triggered at 1.55V. However, this boost converter has a threshold of 2.6V. Is 1.55V a bit too low for lipo? If so, how come the TPS61093 is designed this way?

Thanks


texts: Verilog Testbench with Pipelined Modules

texts:
First I'm very new to verilog.. and test benches are driving me crazy.  I have a pipelined multiplier and I'm trying to write a test bench to auto-check it. My problem is that I apply stimulus to the input, but the correct answer doesn't come out until 5 cycles later.  So in the test bench I'm calculating the answer when the stimulus hits, which will never match the output. I figure there must be an easy solution to this but have yet to figure it out.

Code of my test bench is below.  The module is a 32bit multiplier with pipelines.

Result is calculated after i_Aj & i_Ak are set, however the module does not produce an answer in o_Ai for five cycles. That's the gist of the problem.

module scalar_multiply_tb;

 reg [31:0] i_Aj, i_Ak;
 reg clk;
 wire [31:0] o_Ai;
 reg [32:0] count1, count2;

 initial
 begin
  clk <= 1'b0;
  i_Aj <= 32'b0;
  i_Ak <= 32'b0;

  repeat (50) @(posedge clk);
  //check all possible input
   for(count1 = 1; count1 <= 32'hffffffff; count1 = count1 + 1)  //Aj max 2^32
   begin
     for(count2 = 1; count2 <= 32'hffffffff; count2 = count2 + 1) //Ak max 2^32
      begin
       i_Aj = count1;
       i_Ak = count2;
       @(posedge clk);
      end
    end
  end

  always #10 clk <= ~clk;

  scalar_multiply u_scalar_multiply (i_Ak, i_Aj, clk, o_Ai);
   reg [63:0] Aj_d, Ak_d;
   reg [63:0] result;

   always@(posedge clk)
    begin
     Aj_d <= i_Aj;
     Ak_d <= i_Ak;
    end

    always@(Aj_d or Ak_d)
    begin
      result <= Aj_d*Ak_d;
    end

   always@(result)
    begin
     $display("CLK=%t,Aj=%d,Ak=%d,result=%d,actual=%d", $time,Aj_d,Ak_d,result,o_Ai);
     if(result != o_Ai)
      $display("ERROR: %t,sj=%d,sk=%d,result=%d,actual=%d", $time,Aj_d,Ak_d,result,o_Ai);
     end
    initial begin
     $dumpfile("dump.vcd");
     $dumpvars;
     #32000 $finish;
    end
endmodule


texts:
Let's consider an algorithm (for instance encryption) that has 8 strictly identical steps (the output is used as input of the next step).

Considering that I have enough resources to put 8 "step-modules" on my board
I'm wondering what are the advantages of doing it as a pipeline (8 modules connected in line with some buffers in between) or as 8 separated modules (with a loop on itself via multiplexer and buffer).

If I have a one input port to give the data to encrypt the performance should not change, the overall latency and the throughput will be the same.

simulate this circuit – Schematic created using CircuitLab

On the top: the pipeline, below the parallel (considering only 2 times through the "step-module" and omitting the buffers)

Is there any significant difference?

Further exploration: what if I have not enough space for 8 modules (but maybe only 7) or for more than 8 (maybe 9)?


texts: Are there wireless powering products for a distance of 50 cm? I want to design a sensor tag where it can be recharged wirelessly. Is that possible?


texts: Differences between MIPI-CSI1 and MIPI-CSI2

texts:
I'm trying to find what makes a difference between MIPI-CSI1 and MIPI-CSI2.

From what I understand on this specifications document, they both work the same way, except that MIPI-CSI2 offers up to four data pairs, while MIPI-CSI1 offers only one.

Is this correct?


texts: How to measure noise on an antenna in system

texts:
I am working on an antenna based RF receiver (AM/FM radio) that appears to be picking up interference from other parts of the circuit.  I want to view the noise spectrum, but the receiver chip doesn't expose the actual RF signal, so it's difficult to obtain the noise information.  You can query the receiver chip via I2C to get a few noise related parameters, but it seems like it would be a lot of work to use that information to get a plot-able spectrum (if it's even possible), so I'd like to avoid doing that if I could.

I am new to working with antennas, so I was wondering if there's an easy way to see what the receiver chip is seeing with some sort of probe and plot it out on a oscilloscope or spectrum analyzer.  My first though was to use a low capacitance differential probe between the antenna and ground and plot the FFT on the scope.  See below

My concerns are that a) the probe would load down the antenna and change the antenna response so that I'm not seeing the real noise profile that the system will see, and b) the signal would be so small that I might not be able to see the offending frequencies.

Do anyone have any recommendations or insights?


texts:
Given $$ G(s) = \frac{1}{(s+1)^2} $$ how do I come up with the following time-invariant realizations?

1) Controllable but not observable
2) Not controllable but observable
3) Neither controllable nor observable

I put G(s) into the controller and observable canonical forms and I found both are controllable and observable.


texts: FDM on a multi-subscriber line for which each subscriber has a filter - real world examples

texts:
I recently asked what was, in retrospect, a rather poor question: How does electrical interface on multi-subscriber FDM telephone line work?

In the question, I make a bad assumption about how frequency multiplexed telephone lines work. My assumption was that multiple subscribers connected to a single line with a subscriber side device which could upconvert the baseband signal (SSB modulation) and then achieve isolation from the other subscribers by the use of an analog filter between the final output amplifier and the connection to the shared line. Several amplifiers cannot directly drive a single line, but if filters ensure that there is a high impedance between an amplifier and any other, where the passbands of all amplifiers are mutually exclusive across the frequency domain, then I see no reason this cannot be workable. I made the assumption that this was how telephone infrastructure works in my question and discovered that, in fact, each subscriber gets their own line for the last mile. The multiplexing of subscribers is done by a summing amplifier. I understand this perfectly well; it is a straightforward solution. However, it seems expensive, because of all of the wire you need to make it happen!

My question is, are there any real world examples of what I suggest, subscribers multiplexed by subscriber-side hardware onto a single line, rather than subscribers multiplexed by telecom infrastructure-side hardware connected to many subscribers by many long wires? Can you find such an example? Why is one approach chosen over the other?


texts: Can I connect 500K resistor directly to the mains?

texts:
I would like to test what will happen if I put a high resistor between 220V AC terminals.
My calculations say that it is possible, but I asked this question to know the practical point of view before testing it.
I = 220 / 500k = 0.44 mA
P = I * V = 0.44 * 220 = 96.8 mW
If the maximum power that a resistor can handle is 0.125 watt, the previous calculations allows me to do this experiment. Is that right?
If the maximum power of my resistor is 0.125 watt and I need to apply 0.25 watt to it, can I use two series resistors?
One more thing: Can I calculate the input impedance of a circuit and then connect a suitable resistor in series to the circuit so that I no longer need a transformer? I know that it is too dangerous but is it possible?

simulate this circuit – Schematic created using CircuitLab


texts: Determination of Beta effective and Threshold Voltage of N-33 Mosfet of UMC_180nm library

texts: I have DC simulated the N-33 Mosfet of UMC_180nm library in Cadence and have found different values of Beta effective for different values of Vgs as attached below. Also, the calculated Beta effective from drain current is also not matching with the actual Beta effective. Any help of which Beta effective should I choose for my further design calculations


texts: SPW2430 MEMS MIC Taking time in returning to base Voltage

texts:
BREAKOUT BOARD SCHEMATICCIRCUIT SCHEMATIC

Green probe is for DSO and red probe is for DMM

I am trying to create project using ESP 32 with arduino IDE which turns on when a snap is detected.
I will be using using spw2430 mems mic
datasheet here :Mems MIC Datasheet
Right now I using the Adafruit SPW2430 mems mic breakout board for testing purpose
product site here :https://www.adafruit.com/product/2716

100 to 10kHz frequency resp
VPP= 200mV
Dc bias= 700mV Zout=450 Ohm

The problem I am facing is whenever i snap my fingers or clap my hand the output voltage goes up (as expected) BUT it takes a 4-5 seconds to come back to normal reading .
Ideally it should not take that much amount of time to come back to normal reading. It should take 10 ms to come back to normal readings.

I am polling every 500 microseconds and the attenuation of the ESP32 has been set to 0 db so that the REF voltage scale is in 0 - 1V.
this similar problem is happening with arduino uno (with same set of test conditions) .
The input of adc is connected to the DC pin of the Breakout Board.
(Which does NOT have any capacitor in between the o/p of mic and I/p of adc.)

Here is the code I am using

#include<esp32-hal-adc.h>
#define ANALOG_PIN 4

void setup()
{

  pinMode(ANALOG_PIN,INPUT);
  Serial.begin(115200);
  /*
   * typedef enum
   {
    ADC_0db,      // 0 to 1 v
    ADC_2_5db,  // 0 to 1.27 v
    ADC_6db,     // 0 to 1.75 v
    ADC_11db     // 0 to 3.3 v
   } adc_attenuation_t; // changes Ref Voltage Scale
   */

  analogSetPinAttenuation(ANALOG_PIN,ADC_0db);
 // Set the attenuation for particular pin currently 0-1 v

}

void loop()
{
  int raw_value = 0; // to store raw value of mic

  raw_value = analogRead(ANALOG_PIN); // Reading the op voltage of mic

  Serial.print("Raw value is : ");
  Serial.println(raw_value);

  delayMicroseconds(500); // Sampling every 500 uSec
}

I also have a voltmeter. i connected one probe to GND and OTher one to DC pin output of MEMS Mic. The voltage reading is 700mV. When I snap my finger it reaches 800mV immediately But It takes 4-5 seconds to come back to 700mV


texts: Why are MOSFETs better than BJTs in application of Voltage Controlled Resistor?

texts:
Why are MOSFETs better than BJTs in application of Voltage Controlled Resistor ?
Thanks for your responses.


texts: Can I use MAX232 instead of a ICL7660 to make a split power supply?

texts:
For an opAmp rails I need positive and negative voltages i.e. Vcc, Vee.
I look for a good IC which is commonly used for creating split power from a single power supply. Many recommends ICL7660. I currently have a MAX232. Can it be used instead? I need +5V -5V or +9V -9V or +12V -12V all would work.


texts: Microcontroller clock speed vs internal oscillator

texts: I'm having a little trouble understanding the difference between an internal oscillator and clock speed of microcontrollers. I was under the impression the the internal oscillator oscillates at a certain frequency which IS the clock speed but I get the feeling that I'm wrong. I've seen the PIC16F690 datasheet that says that the oscillator can run up to 8MHz but the clock speed is 20MHz. Or is that 20MHz a maximum if an external clock is used?


texts: Transfer function of a filter: where is my mistake?

texts:
So, I'm trying to derive the transfer function of the following circuit:

with $$R_L=3R$$
So my attempt was to treat the circuit as 3 cascaded blocks, obtaining the following transfer functions:
$$\frac{V_{o1}(s)}{V_i(s)}=\frac{1}{1+sCR}$$
$$\frac{V_{o2}(s)}{V_{o1}(s)}=\frac{1}{1+sCR}$$
$$\frac{V_{o}(s)}{V_{o2}(s)}=\frac{3R}{4R+s3CR^2}$$
Then to obtain the transfer function I multiply the 3, obtaining:
$$\frac{V_{o1}(s)}{V_i(s)}=\frac{3R}{3C^3R^4s^3+10C^2R^3s^2+11CR^2s+4R}$$
And putting in canonical form:
$$\frac{V_{o}(s)}{V_i(s)}=\frac{\frac{1}{R^3C^3}}{s^3+\frac{10}{3RC}s^2+\frac{11}{3R^2C^2}s+\frac{4}{3R^3C^3}}$$
However my book obtains this answer instead
$$\frac{V_{o}(s)}{V_i(s)}=\frac{\frac{1}{R^3C^3}}{s^3+\frac{16}{3RC}s^2+\frac{22}{3R^2C^2}s+\frac{2}{R^3C^3}}$$
So I might be making some sort of mistake with the coefficients in the original transfer function. I've already redone this multiple times and can't find my mistake. Can someone help me please?


texts:
I'm using a known good FTDI USB -> UART bridge to talk to a 3rd part module on my board. I've just assembled the board, and it's not impossible that I fried a component in the process (it's what I'm trying to understand right now)

When I send data through the UART, I get this:

The yellow is the incoming TX (RX from the module's perspective) line and the blue is the RX. As you can see, data is coming in fine, but it's causing this weird "echo" effect on the module's TX pin, with no response from the module (I'd expect something back).

The module is a Bluetooth module I've worked with before, connected like this:

(the TX and RX lines are flipped appropriately on the FTDI connection)

Any ideas what this is? Is it just a fried module?


texts: How to invert one channel of phone output?

texts:
I want to connect phone output to a car radio. It has + and - inputs. When I connect left channel to the + input, there is good quality sound, but it's not as loud as CD player. If I invert right channel, then plug it in the - input, the sound should be 6 dB louder. I know that this can be done with an inverting amplifier, but is there a way to do this programmatically on android?

Btw is 1,5 degree phase change too much for bass? I simulated this circuit and these are the results.

If I change R4 and R5 to 50 kΩ, phase and magnitude changes will decrease. On the other side, transient start up time and noise will increase, but besides that, will anything else be affected, like input bias current correction?

EDIT:
This is Sound System manual(page 38).


texts:
My teacher was teaching me about analog multiplier and divider using opamp. Following is the circuit is made us write.

simulate this circuit – Schematic created using CircuitLab

Could someone please explain me how is it working and where it is used. A little detail and further reading source is appreciated.


texts: How to find peak to peak and rms current for square wave AC circuit?

texts: I have a circuit with AC square wave at 10V and 4 Hz. There is only a single resistor of 1000 ohm in the circuit. I would like to calculate the rms current and also the peak to peak current of this circuit.


texts:
I have some device with ac/dc adapter [9v, 500mA], and I want to replace the adapter with batteries.

If I used [6 * 1.5v] battries, is that acceptable? do I have to worry about the max current of the batteries? could the current of the batteries exceeds 500mA?

whenever I try to measure the current of the device connected to the battries, it gives me "1" "the upperlimit of the Multimeter", why? how?

And if so, what should I do?

HOW CAN I MEASURE THE MAX CURRENT OF THE BATTERIES OR SOME POWERSUPPLY???


texts:
I am reading the wikipedia article about the JTAG. It says:

  In the 1980s, multi-layer circuit boards and non-lead-frame integrated
  circuits (ICs) were becoming standard and connections were being made
  between ICs that were not available to probes. The majority of
  manufacturing and field faults in circuit boards were due to poor
  solder joints on the boards, imperfections in board connections, or
  the bonds and bond wires from IC pads to pin lead frames. The Joint
  Test Action Group (JTAG) was formed in 1985 to provide a pins-out view
  from one IC pad to another so these faults could be discovered.

So what does the pins-out view mean?

(PS. I am just moving into the EE world, appreciate if plain English is used. :) )


texts: How does "bidirectional" transmission on gigabit ethernet work?

texts:
I was reading about the various twisted pair protocols, being distracted by the marvels of Wikipedia when I went to look up the way to wire a connector.

And I'm wondering how it can transmit in both directions at the same time over the same conductor?  I assume I read that correctly, since if they take turns it would not be called full duplex.

And why is that better than using two (different) pairs in each direction?


texts: SPI design and general sequential design problem

texts:
I'm trying to describe the following behaviour of MCP4921 DAC.

I'm using Basys 2 FPGA board as the master.

I've written the following code. Which works somehow.

module SPI_DAC_MCP4921(
input [11:0] Data ,
input Clk,
output SCK,
output reg CS_L, //chip select low signal
output reg SPI   // serial data
);

assign SCK = Clk;
reg [4:0] counter=0;    //20 tick counter
parameter [3:0] write_command = 4'b0111; // Anot=0 BUF=1? GAnot=1 SHDNnot=1?
//reg [15:0] write_command_register = {write_command, Data}; // 16 bit write register
always @ (posedge Clk) begin
        if (counter==0 | counter < 4) begin   // first 4 bits
         CS_L <= 1'b0;                        // set CS_L active
         SPI <= write_command[3-counter];     // send 4 bit write command
         counter <= counter+1;
        end else if (counter >=4 & counter <=15) begin  //12 bits
         SPI <= Data[15-counter];       //send data bits, starting with MSB
         counter <= counter+1;
        end else if (counter > 15 & counter <=18) begin    //deactivate CS_L
         CS_L <= 1'b1;
         counter <= counter+1;
        end else if (counter ==19) counter <= 1'b0; // 20th tick reset counter
        //counter <= counter+1;
    end
endmodule

The problem is, while writing in HDL, I don't think about the actual hardware. I don't have a methodology. Should I sketch a state diagram? How should I sketch the flow? I mean I understand the combinational blocks; muxes, adders, comparators etc. and memory elements ff.s , registers. Combining these blocks for a more complex design proves to be difficult for me. I'm looking for improvements to my code, general style tips. Any help is appreciated.


texts: I am a beginner with PCBs and wanted to start making some. But before I did, I wanted to make sure I was completely prepared. I just wanted to make sure that the information I have is correct and had another question. How do you dispose of Ferric Chloride? While researching, I found out that the most popular way is using washing soda to neutralize it and then pour it down the drain after it is completely neutralized (measured with pH paper). Is this correct? Also, I read that using this method leads to a copper "sludge" being left behind. How do I then dispose of this "sludge"? Finally, how much can I reuse the ferric chloride? I just want to know how to dispose of this with keeping the environment in mind.


texts:
Is there a specific way Outrunners are normally wound? (Wye or Delta)

What are the pros/cons to winding the motor a certain way?


texts: I'm trying to understand what I believe to be a basic/fundamental theory, however, I seem to be over analyzing. On many hvac units the 24v or 120v control transformer common is grounded to the unit chassis. This brings the common to ground potential and helps with troubleshooting. Wouldn't grounding the common, which it obviously doesn't, unless in the event of a short, cause unwanted voltage to continuously energize the chassis or just act as a short? Why is it that it is safe to do this and the common has no voltage? Is the voltage lost/consumed through resistive loads in the circuit, such as contactor coils? I assume there is a logical and basic explanation to this and I just need it dumbed down. Any info is greatly appreciated, thank you!


texts: Connecting input and output to the same bus

texts:
I'm reading "But how do it know". And in register chapter, it talks about connecting both input and output pins to a bus. I tried to do it on Logisim but it shows red wires.
Can someone please explain what a bus really is in this case?
Here's the picture of the register subcircuit, and how it was built.
I'm new into electronics. Please ask if more info is needed. Thank you very much.


texts: Polarity of the voltage drop on inductance

texts:
We know from the Lenz's law that the induced voltage on an inductance has the polarity that determines an oppisition to the variation that has generated it.

But in circuit theory the inductance is seen not as a voltage source, but as an impedance. The convention is to say that the voltage drop on it is equal to VL = jwL I, with VL is opposed to the direction of I (if we run across the inductance in the current direction we see that the potential decreases). But, why is this true? I think it depends on if I is increasing (dI/dt >0) or decreasing (dI/dt<0). In the first case, VL will be opposed to the voltage source that provoked the increase of I; in the second one, VL will be opposed to the voltage source that provoked the decrease of I. How can the previous convention work?

For a resistance, saying that "if we run across the inductance in the current direction we see that the potential decreases" is ok for me, but for an inductance, how can it be ok? It should depend on the derivative of the current, not on the current.


texts: Determining R and C for the output filter of the ACS758xCB current sense IC

texts:
I plan to use a current sensor on hexacopter drone (50-150A consumption). The ACS758xCB datasheet gives no information on Rf and Cf. Please advise the values. My application is measuring current my drone takes from a LiPo battery. Sampling rate may be 100-500Hz.

Here are several tasks I want it for:

Protection: I will set up warnings, if something goes
wrong and current consumption goes abnormal, I will receive alert.
Remaining battery charge measurement: as battery will
discharge I will receive warnings.
Total energy consumption: I will record how much I spent in the flight and compare to how much I am charging back to the battery.


texts: Questions about Solder Mask Expansion Rules and Passive design in Altium

texts:
I am working on my first Systems project as a student and I am learning how to integrate chips as I go along in Altium.

I recently came across this question in which you provided a rule for determining the solder mask expansion sizes for BGA Chips: What is the pad size required for this BGA AW H3 Chip?

I am wondering if there is a similar set of rules for QFN chips? We have a PMIC that we are integrating on Altium and we just want to make sure that our solder mask expansion sizes are sufficient. Currently we have the small pads having dimensions of 0.25x0.50mm and a solder mask expansion of 0.05mm.

Here's the link to the QFN Chip:

Also, we are drawing the footprints for the passives that we are going to use (0402,0603, 1005, etc.). Will it be okay to have the same footprint (with relaxed dimensions) for Capacitors, Resistors, and Inductors? What is an appropriate way to design the footprint for the passives?


texts: Does a Mcp23s17 output pin keep the value after being unselected?

texts:
I'm designing a SPI based communiations circuit between Raspberry Pi4+B as a master and (n x 8) GPIO expander modules, as slaves. Concretely we have selected an MCP23S17 GPIO expander: Datasheet

By the moment I will try if the system is able to write 0 or 1 to the GPIO = outputs. After this, I will be testing the reading pin values from GPIO = inputs.

I would like to know if someone has worked with this, and I will also ask for some things if for example:

I access any of the expansor modules and I write some output pins (1 or 0)
After write operation we access another expansor modules for carry out any operation like the previous one

What happens with the first output pin value of the first operation? Does the expansor device keep the previous pins state even if the expansor module is not acceded (unselected) yet?

I have read datasheet and application notes. I don't find there any information that makes me think that the state is "erased" after being unselected.

I have another question about something read at datasheet.
"each pin can be configured emulating open drain configuration" --> what does it mean? and for what is useful this option?

By the information that I've seen it's similar to use pull up/down, but getting more current. It can be also used for passing one level signal to another level signal, between CIs. But when is it better than using only pull up/down resistors? When can I get advantage of using a pin with this configuration?

Any help will be appreciated.


texts: How generate a square wave from a DC voltage to power on LCD crystals?

texts:
I got a small LCD and I would like to power it to show the LCD crystals turning to black.

I would like to show at which voltage the LCD crystals start to turn black.

I did some research about LCD and I saw I probably have to power it with square wave.

Do you have any idea of how I could create a square wave from a DC voltage using basic components?

I saw it could work with a NE555 chip but I don't have this one and I think it could be done in a circuit with simpler components.


texts: What is the electrical benefit of keeping a running disparity on a bus?

texts:
I've always been taught that an interface with no DC offset (the same amount of 1s and 0s when averaged over time) is desirable. To this end, often encodings like 8b10b will include a running disparity which compensates accordingly.

Looking at the wikipedia entry for 8b10b, it mentions that the discrepancy between 1s and zeros is limited to 2 either way:

  8b/10b coding is DC-free, meaning that the long-term ratio of ones and
  zeros transmitted is exactly 50%. To achieve this, the difference
  between the number of ones transmitted and the number of zeros
  transmitted is always limited to ±2, and at the end of each symbol, it
  is either +1 or −1. This difference is known as the running disparity
  (RD).

Over a long period, this is an incrediby small tolerance for the duty cycle.

What is the electrical benefit of doing this?


texts: VHDL: Declaring an empty array (in a test bench)

texts:
The question is pretty simple: is it possible to declare an empty array in VHDL?

Here is my problem: I am trying to write a module(for an exercise in Peter Ashenden's book), that will find the biggest integer in an unconstrained array of integers and detect empty arrays:

type int_set is array(integer range <>) of integer;

My module looks like this:

entity maximum is
    port ( vector_in : in int_set;
           data_out : out integer;
           valid_in : out std_ulogic ); -- will be false, when vector_in is empty
end entity maximum;

-- behavioral body
architecture behav of maximum is
begin
    maximum_behavioral : process ( vector_in ) is
        variable temp_max : integer := integer'low;
    begin
        -- reset temp variable
        temp_max := integer'low;
        -- test for empty array
        if vector_in'length = 0 then
            valid_in <= '0';
        else
            for i in vector_in'range loop
                if vector_in(i) > temp_max then
                    temp_max := vector_in(i);
                end if;
            end loop;
            data_out <= temp_max;
            valid_in <= '1';
        end if;
    end process maximum_behavioral;
end architecture behav;

Now in my test bench I have a number of arrays/sets to test my module:

entity int_max_tb is
end entity int_max_tb;

architecture test_int_max of int_max_tb is
    signal data_in : int_set(0 to 4);
    signal data_out : integer;
    signal valid_in : std_ulogic;
begin
    max_dut : entity work.maximum(behav)
        port map ( data_in, data_out, valid_in );

    stimulus : process is
        -- test arrays/sets
        constant set1 : int_set := (4, 5, 6, 5, 3);
        constant set2 : int_set := (7, 6, 5, 10, 4);
        constant set3 : int_set := (-7, -6, -5, -10, -4);
    begin
        data_in <= set1; wait for 10 ns;
        data_in <= set2; wait for 10 ns;
        data_in <= set3; wait for 10 ns;
        wait;
    end process stimulus;
end architecture test_int_max;

So far, this works fine and yields the results I expect. But now I want to test it against an empty array. Adding something along the lines of

constant set4 : int_set(0 to 4);
-- and later on
data_in <= set4;

won't work obviously, since a constant needs to be initialized with some values. Changing constant to variable will work, but the result will be an array with five elements each of the value integer'low - again, this is expected behavior.

Specifically, the exercise asks: How should the module behave if the actual array associated with the input port is empty (i.e., of zero length)?

From this statement, I assume that it is possible to declare(or have some code produce) an empty array. But the answer to this could also simply be, that a module does not need to detect an empty array since once an object of an unconstrained array is declared, I need to provide constraints specifying the index bounds of that object(and will assign default values to the elements if unspecified).

From this question I infer that it is possible to have zero-length arrays if one uses generics(which I am not, so far).

So in conclusion: Can I declare an empty/zero-length array in VHDL(without generics) or is it simply not possible(which I am thinking right now, taken the arguments from the two paragraphs right above this one)?


texts:
Below is an LTSpice simulation of a 'radio button' circuilt.
Ignore the bottom button, I am working on a 'reset' mechanism to unlatch any of the other buttons.

The idea is that the button you push, unlatches any other button and latches the button you pushed.

Does anyone know of a jellybean part (some 74 series type chip) that will do this?


texts: Fried motherboard resistors, what to do?

texts:
A motherboard failed under load recently, and here is the worry:

I am waiting for a new mainboard. What must i do about it? is it a very easy repair? I am mostly confused about identifying the resistors.


texts:
In a power management integrated circuit (PMIC) documentation I came across a programmable dead-time parameter for a DC-DC converter.

What does dead-time of a DC-DC converter/regulator mean?

What role does it play a role in shaping the efficiency of the DC-DC converter?


texts: Microcontroller hangs while switching off

texts:
In my application I have interfaced ESP8266 wifi chip with ATTiny828 micro-controller. We have developed our custom module with these two chips on it. The problem we are facing is that the micro-controller hangs sometimes when switching off the module. The button is the momentary type "push to On" switch and power ON/OFF functionality is implemented with the following circuit :

when the switch is pressed npn transistor turns ON which in turn makes PMOS conduct current and makes the entire unit ON. As soon as the micro-controller gets started it puts ON/OFF pin in permanently HIGH state (to keep the unit powered on after the switch has been released). "SENSE" pin of the micro-controller senses the state of the switch (Pin change interrupts are active on this pin). So if the switch is pressed for more than a pre-programmed span of time, then micro-controller will make ON/OFF pin zero which will turn off the module.

we have taken care of debouncing in the software by adding delay of 100 ms.
here is our code

// PW pin is same as "SENSE" pin
ISR(PCINT0_vect) {
    static uint8_t tmr_pw_start = 0;
    static uint8_t PW_prev = 1, GP2_prev = 1;

    uint8_t const PW = READ(PW);
    uint8_t const GP2 = READ(GPIO2);

    if (PW != PW_prev) {
        if (PW) {               // Start measuring button press time
            tmr_pw_start = 1;
            ovf0 = 0;
        } else if(tmr_pw_start){
            if (ovf0 > 60) {
                WRITE(On_off_pin, LOW);     // POWER OFF
                _delay_ms(100);
            }
            tmr_pw_start = 0;
        }
    }

    if (GP2 != GP2_prev) {
        TOGGLE(BLUE_LED);
    }
    PW_prev = PW;
    GP2_prev = GP2;
}

ISR(TIMER0_OVF_vect, ISR_NOBLOCK) {
    ovf0++;
    if(!(ovf0 % 16))    TOGGLE(GREEN_LED);
}

We keep timer 0 always running and its number of overflows are used to measure elapsed time. it takes approx. 32 ms for one overflow to occur.

Other than this UART interrupts are also active in which it just takes the data and assigns it to a global variable.

The problem is this :
By pressing the switch ON/OFF button for more than 2 seconds and then releasing it should switch off the unit which it does most of the time. But in 1 out of 15 cases micro-controller hangs while switching it off. It becomes unresponsive to button press and LEDs stop blinking. Or sometimes it becomes unresponsive with GREEN led still blinking.

Can anyone guess what can be the problem ?


texts: How to make the HT12E transmit (TE to low) only when one or both buttons are pressed?

texts:
I followed this video: https://www.youtube.com/watch?v=-xK0B_bM-yk and made these circuits:

Transmitter:

Receiver:

And they work as I want them to. I have 2 pushbuttons so when one or both of them are being pressed, the corresponding LED/s on the receiver side light up, and when one or both of the pushbuttons are no longer pressed, the corresponding LED/s turn off (no latching on the HT12D decoder side because TE is constantly transmitting as it's hooked up to GND).

My question is - how can I (since battery life is important in my case) enable TE only when one or both of the buttons are pressed or stop being pressed. My goal is to not transmit all the time because I want to save battery. And also I don't want the LEDs to latch upon the receiver side so when the pushbutton/s stop getting pressed, I need the LED/s to turn off. What would be the simplest and most space-efficient (in terms of SMD components) way to do this?


texts:
I am trying to connect STMWIn starter kit to Microsoft azure.
I have successfully transferred the binary file which is taken from official ST site and transferred it to the board.
I was also able to configure the wifi credentials and the decide, scope ID.
After that on Tera Term it shows that
network interface starting
But in the cloud Azure there is no data incoming.
What could be the reason for same?


texts: recently I was going through a thyristor's data sheet, I saw one unfamiliar parameter called "threshold voltage " , can somebody explain what it is?


texts: Is there software for converting a picture of a board into an schematic?

texts:
I need to reverse-engineer several simple single-sided boards. I have very good quality pictures of them so I was thinking that maybe there is software capable of getting the schematic from the pictures (up & down) or at least an approximation.

How can I reverse engineer PCB's easily?


texts:
I'm a total noob when it comes to the use of opto-couplers, but I'm trying to connect up a couple of digital pins between an ESP32 and a small voice module.  There are two pins that I need to switch in order to do remote-updates on the second device from the ESP32.

One pin is a programming mode pin that has an internal pull down. It needs to be set 'high' prior to a reset to trigger a given device mode.
The second pin is a reset pin with an internal pull-up that needs to be pulled low (shunted to ground) momentarily to trigger a device reset.

I basically need to pull the one pin high, momentarily connect the reset pin to ground (pull it low) then I can release the other pin after the reset is triggered (probably with a slight delay - not sure how quickly this thing detects the mode pin).

I'm sure there's a way to do it, but not being familiar with how the opto-couplers work in a circuit and not being an EE, I'm not even sure where to begin.

Oh and I forgot to add, my ESP32 board has built-in level converters as does the module, thus I'm operating with 5V.


texts: Electrostatic discharge threats to microcontrollers on a PCB in a semi enclosed metal case?

texts:
Can the microcontrollers on a PCB inside a metal case (one side is open) get damaged by ESD when the case is touched? If so what can I do to protect the components inside the case from getting damaged? To minimize the ESD threat should I isolate the PCB from the case or should I connect the PCB ground to the case?
The PCB has a USB-C port and the case has one open side. In my specific case I am talking about the PCB of a custom USB mechanical keyboard inside of an aluminum case.


texts:
I'm designing a battery powered device, which must be turned on by an external 3.3V impulse from a comparator output (TLV3201), and for the sake of power efficiency I want the MCU to power itself off when it has finished processing the event. For the self-poweroff circuit I've found the following solution:

The P-channel MOSFET is powered off by default by pulling it's gate to VCC via R1, but when the EN pin is pulled high, either by the comparator (push-pull op-amp) output or the MCU (after it has got power), the P-channel switch is opened to supply power to the MCU.

The problem is that the high signal from the comparator may stay high for many seconds, even after the MCU has done it's work, and I want the MCU to be able to shutdown the power regardless of the comparator output (after it has initially enabled the switch) until the next time the comparator output rises. How could that be done?

Edit:

Added schematic of the comparator circuit.
The power supply is an unregulated Li-Ion battery (~3.7V). The 3.3V regulator is to be placed after the P-channel switch as part of the Load.

The comparator is used to sense the resistance connected between IN1 and IN2, which may switch between ~1.5 kOhm and ~5.5 kOhm. 1.5 kOhm resistance results in a high level output of the comparator, and 5.5 kOhm is low level (0V) output.

simulate this circuit – Schematic created using CircuitLab

Edit 2: The MCU will be a ESP-07 Wi-Fi module (ESP8266). I am currently researching its deep sleep capabilities and power consumption.


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I wanted to know what is the relationship between a square wave and its harmonics, in other words can i change a square wave features (frequency, duty cycle etc) to obtained a desired fundamental frequency (and its corresponding harmonics)?
Any help would be appreciated thanks.


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I'm working in the IoT field and just got started with the WiFi module ESP8266-01. I know how to use the AT comands and HTTP requests, but I want to use MQTT protocol.

I have found this library: https://github.com/tuanpmt/espduino, which seems to be good. But it was designed to use with Arduino and I only know AVR. I know Arduino "is" AVR, but reading C++ code to find out how this library works makes me so confuse!

Can someone please explain to me how this espduino library works? For example: How are the commands sent? What commands are sent to connect to Wifi, connect to a broker, subscribe to a topic, publish data etc. So that I can use those methods with AVR in avr-gcc code.

Any links to some tutorials or other helpful MQTT libraries are fine too.


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Did I damaged the panel? How can I test if everything is ok?


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To make things even more confusing, this guy has done something similar to what I wanted to do using this which is only around $6.

But I've also seen other projects that are done using the shield, so what to buy? I don't really care about the price, I am willing to pay, but I don't know which one to buy.

At first I thought that Arduino bluetooth shield is a shield (cover) that protects the module but this guy was able to connect Arduino using the shield only.

My questions are: what is the difference between the shield and the module? What are the differences between different Arduino bluetooth modules? What do you usually buy to connect an android device to Arduino using bluetooth?


texts: I have some PCB's that I have ordered from China. The PCB has a BGA component along with traces which go from the BGA component to another BGA IC(USB controller) and finally to USB. Right now I am very interested in 2 lines on a PCB. I think I can find the trace which is going but it is insulated. I dont want to cut the trace and bring out a wire and reattach the wire to the other part of a trace to probe the line on my Logic Analyzer. Is there any other chemical which will easily remove the insulation and expose the copper and help me probe the trace? What are the alternative I have?


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I have a 220VAC:1200VAC 800VA 60Hz toroidal voltage transformer and I'd like to measure its parameters to simulate a circuit I'm gonna build with it, in order to understand better the transients. The measurements doesn't need to be very accurate. I have a very limited knowledge about transformers. My questions are:

Is it OK to measure the primary leakage inductance using and LCR meter @ 120Hz? The secondary should be open or shorted (and why)?
Is it OK to measure the secondary leakage inductance using and LCR meter @ 120Hz? The primary should be open or shorted?
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Also, I'm having trouble to simulate transformer models in OrCAD Capture CIS. Would something like this be fine for my analyzis?


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When I switch a 12v relay from ON to OFF using esp32  then the ESP is restarted. Also it  happens only when there is an AC load. I control 12V relay with a transistor.
This is my relay

How to solve this

Edit 1-- When I changed the load to a light bulb it works normally fine. But when I switch back to Induction motors the problem persists.

Circuit link


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I am looking at the specs of tactile pressure sensor and I can't understand what this means:

"Drift: <3.3% per logarithmic time scale"

How should I understand this? Does this sensor drifts a lot or this is actual good. I am looking for cheap way for measuring wight changes over a long period of time.

Cheers Mitko.


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I'm studying switching converters and the input voltage of a Buck, Boost, or whatever is designated as \$V_g\$. I've racked my brain (and also searched Google), but I can't work out what the 'g' could possibly stand for.

I suppose it's one of those things that is so obvious once known that no one thinks to mention it.

What does the 'g' stand for? Why isn't it just \$V_{in}\$ or something straightforward like that?