texts: Differential equation mixed RLC-circuit, C parallel to RL

texts:
I am having trouble finding the differential equation of a mixed RLC-circuit, where C is parallel to RL. It is a steady-state sinusoidal AC circuit. I need it to determine the Power Factor explicitly as a function of the components. I know I am supposed to use the KCL or KVL, but I can't seem to derive the correct one.

I am actually a math student, so I apologize if this question is straight forward.


texts:
Below program is written in AVR studio. Connections: PORTD pins 0 to 7 are connected to data lines of LCD i.e. DB0 to DB7 respectively, PORTB.1 connected to RS, PORTB.2 connected to R/W and PORTB.3 connected to EN of 16x2 LCD JHD 162A.

In program PORTD.7 is checked whether it is busy or not.

Characters do not seem to be displaying. Any suggestion or help would be greatly appreciated.

 #include<avr\io.h>

    void lcdcmd(unsigned char value);
    void lcddata(unsigned char value);
    void lcdready();
    void MSDelay(unsigned int time);
    int main()
    {
        DDRD=0xFF;
        DDRB=0xFF;
        PORTB = 0x00;

            lcdcmd(0x38);

            lcdcmd(0x0E);

            lcdcmd(0x01);

            lcdcmd(0x06);

            lcdcmd(0x86);

            lcddata('M');

            lcddata('D');

            lcddata('E');
        while(1);
        return 0;
    }

    void lcdcmd(unsigned char value)
    {
        lcdready();
        PORTD=value;
        PORTB=PORTB & ~(0b00000010); // rs
        PORTB=PORTB & ~(0b00000100); // rw
        PORTB=PORTB & ~(0b00001000); // en
        MSDelay(1);
        PORTB=PORTB | 0b00001000;
        return;
    }

    void lcddata(unsigned char value)
    {
        lcdready();
        PORTD=value;
        PORTB=PORTB & ~(0b00000010); // rs
        PORTB=PORTB & ~(0b00000100); // rw
        PORTB=PORTB & ~(0b00001000); // en
        MSDelay(1);
        PORTB=PORTB | 0b00001000;
        return;
    }

    void lcdready()
    {
        unsigned char temp;
        PORTD = 0x00;
        temp= PORTD | (1<<7);
        PORTD= temp;
        PORTB=PORTB & ~(0b00000010); // rs
        PORTB=PORTB | 0b00000100; // rw
        while(temp==1)
        {
            PORTB=PORTB & ~(0b00001000); // en
            MSDelay(1);
            PORTB=PORTB | 0b00001000;
            temp= PORTD & (1<<7);
        }
        return;
    }

    void MSDelay(unsigned int time)
    {
        unsigned int i,j;
        for(i=0;i<time;i++)
            for(j=0;j<1275;j++);
    }


texts: PWM controlled Input Voltage/Current regulated Converter (for solar panel)

texts:
(newbie question)
Briefly: In a converter (let's say DC-DC), I want to dictate a voltage to the output of solar panel, on the fly.

As I look around online, for example in some IEEE papers, Buck or Boost converters are used to regulate the second stage: the charging current and voltage. I studied them a bit. But I don't understand: Does changing their duty cycle, regulate their input voltage too? If not, what kind of IC regulates input, based on given duty cycle? Please note that I don't want an on-chip MPPT solution. But to regulate the input of my converter i.e. the output of the solar panel. A microprocessor will specify the voltage of solar panel, through PWM duty cycles.

Going through the products of T.I. or Linear I did not find such an Item.

Solar panel's typical power output would be in the range of 5w...

In this project, it is not important what the charging voltage (second stage) is, actually.

I'll gladly edit, clarify or rephrase the question or title, if you see a problem.


texts: Is it possible to sweep 20 Hz to 20 kHz with one potentiometer?

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I'm designing a resonant filter based on a state variable filter topology with sweepable frequency and variable resonance. The filter is designed to sweep from roughly 20 Hz up to 20 kHz (50 kohm linear dual gang potentiometer with 50 ohm limiting resistors and 180 nF capacitors). The prototype works fine and sounds good however, both in the simulation and on the prototype, when turning the potentiometer to sweep the frequency band, 75% of the pot's turn works from 20 Hz to roughly 80 Hz or 100 Hz and the remaining 25% of the pot's turn sweeps up to 20 kHz. Is there a way to sweep the entire audible frequency band using one potentiometer while resolving the pot's sensitivity at high frequency? (cutoff frequency vs pot rotation).

Any help would be greatly appreciated!


texts: I am trying to simulate button presses on a cell phone by using the Arduino to complete the button circuit thus simulating a button press. I figured out I have to use a transistor but I can't get it to work.


texts:
I have a (input) 230V  and (output) 12-0-12 AC to AC transformer.
I want to know how know its primary turns, secondary turns and its secondary voltage?


texts: Calculating impedance in a two-way speaker crossover

texts:
I'm trying to come up with a basic two-way crossover for a speaker I'm building out of scrap. (Working with what I've got - no new parts.) My amp handles 8-16 ohms.

Here's what I've come up with for a speaker design so far:

simulate this circuit – Schematic created using CircuitLab

I've just got the one inductor, but I've got a ton of different capacitors. I'm planning to build the capacitor out of a combination of smaller ones in parallel. (10, 5, 1, and 0.5.)

My primary question is: How would I calculate the nominal impedance?

Secondary questions:
 - I believe this crossover is set to 12kHz; did I do my math right for this?
 - Since the tweeter is 6 ohms, will be attenuated enough so that it won't overwhelm the woofers?

Additional info:
 - I'm not looking for this to be a fancy system. Just something that will sound ok and not blow up my amp.
 - This is really just a re-working of the existing components in the original speaker. My intention was just to see if I could adjust a few things and increase the impedance to >8 ohms. (So it won't blow up my amp...)
 - I based my design on the series circuit in figure 1.1 here.

A bit of background: I pulled apart a pair of Samsung surround speakers (3 ohm) and I'm trying to make it into something I can use with my RCA STAV-4090 receiver. The exact driver models are a mystery - no spec sheets available, unfortunately. Two of the four speakers say "F30C-D998-1 75108" and the other two say "F30C-D998-1 74208". (The difference being 51 vs 42 - any ideas what they could mean?)

From what I can see, here's what the circuit looked like in the original:

simulate this circuit

I believe this circuit was a cheap attempt at a three-way crossover? The tweeter gets a high-pass, the center driver effectively gets a low-pass from the leftover, and the bottom driver has its own low-pass filter. (Is this right?)


texts: covering sides of LEDS without adding heat

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I'm doing a project in which a 5mm LED is near a 5mm phototransistor. There are times in which the sensor must pick up external light even with the LED on.

I understand one option is to turn the LEDs off everytime I want to sense light, but that means the microcontroller will run slower overall (as it spends time turning the LED on and off) and flickering might drain batteries faster.

So I'm opting for a second option. Using heat-shrink tubing to cover up the sides of the LED's so they don't affect the nearby sensor.

I have tried 5mm heat-shrink tubing on a 5mm led and it fits decently but somewhat loose. They say the traditional way is to use a blow-dryer on very low heat to tighten the tubing to the LED, but I was thinking maybe theres a better approach.

Online there is an option to buy 6mm tubing as well (http://futurlec.com/Cable.shtml).

So other than applying heat, which of the following is better to secure the tubing to the LED?

Should I buy 5mm and 6mm tubing, put the 5mm tubing on the LED and force the 6mm tubing over the 5mm tubing in place?

or

Should I change 6mm to a higher number for 2nd tubing size?

or should I get a larger tube diameter and use some tool (I don't know the name of it) to feed it through itself (so one end looks like a cup rim and the other end looks cut)?

or is there a specialized tool to actually cover the LED completely?

I thought of led holders and clips but they cover only parts of the sides or they angle the LED the wrong way. Also the sensor side is about 6mm maximum away from the LED side.


texts: Find the peak load of a power plant for the given load equation

texts:
The daily load demand of a grid is given by

$$P=P_{max} \cdot cos(\pi t/24)$$

Here \$-12hrs ≤ t ≤ 12hrs\$. Maximum power occurs at (\$t=0\$) and minimum occurs at (\$t= ±12\$). A \$10 GW\$ hydro power plant with pump storage is available for base load operation. The turn-around efficiency of the storage system is \$0.7\$. Find the peak load.

I found the average power in terms of \$P_{max}\$, by integration of the above over -12 to 12 and then dividing by 24, which comes out to be: \$P_{avg}=2 P_{max}/\pi\$. but now I couldn't figure out how to proceed. Any help will be greatly appreciated.


texts: I came up with the circuit below to drive a single 7-segment display from an Arduino via a shift register (74LS595). Is the circuit correct/good enough or am I perhaps missing something critical in the design?


texts: Why am I getting very different measurement results on a breadboard?

texts:
I have an AC to DC multiple output adapter. It has the following output:

I set the voltage to 5V. When I measure the supplied current, I get 3.26A.

Then I connect an output to it:

When I measure the supplied current now, I get 3.23A.

Then I try to measure the current on a breadboard:

And I get 0.02A!

What is going on? Why is this happening?

More interestingly, I have discovered that the LED on my adapter gets dim proportional to the current it supplies. However, in all three measurements, although the results differ (especially the last result), the LED gets exactly the same amount dimmer. So this is a curious point as well.

Could you explain why the measurement on breadboard differs so much?


texts: Logging lithium battery discharge: why this curve?

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I'm using Arduino to log the discharge curve of a 5V battery pack (usb type for smartphone recharging).
Using Arduino I read the voltage every second and I save it to a log file.
Arduino is powered by an external source, the battery pack is connected to a 4.8 ohm resistive load to have about 1 ampere of draining.

simulate this circuit – Schematic created using CircuitLab

I'm using the volt divider because arduino Analog pin has 0-5v range, so I read 2.5V and then I multiply it by two.

But I have an issue: as you can see the discharge curve go up, and down, and up again and then it stop with a value that is high. I check the battery and is empty, but I don't know how I obtain this discharge curve instead of something like this:


texts: dynamic gain control for active noise cancellation circuit

texts:
I'm an entry- to mid-level electronics hobbyist and I've been tinkering around with a simple active noise cancellation circuit (audio frequencies) based in principle on the schematic here: http://headwize.com/?page_id=684

I've obtained fairly decent performance prototyping with some spare op-amps. The biggest problem (for me) is that the circuit depends on a potentiometer to manually adjust the volume of the inverted noise signal before it is summed back into the noise signal. In real life, this requires constant manual adjustment to zero out the noise as the noise level volume fluctuates over time.

EDIT: Although the original design allows for the anti-phase noise signal to be summed with a desired audio signal (ie, music), I am using the headphones only to attempt to create artificial silence.

So I want to improve the design to auto-control the inverted signal gain so as to always sum as close to zero as possible.  Does anyone have good ideas on how to accomplish this (without using a microcontroller)?  I was thinking of some type of comparator circuit or maybe I should move directly to a voltage-controlled amplifier for the the inverting op-amp? I really don't have any familiarity with these sort of circuits.

If anyone has a relevant circuit schematic or op amp model recommendations, it would be much appreciated.


texts: Why is my oscilloscope reading jittering, and how might I fix it?

texts:
I've made a simple inverter circuit and I've read the voltage across the load resistor using a RIGOL DS1104 oscilloscope.  Here is the link to the screen capture.  I'm using a full-bridge inverter topology, I'm using an Arduino Uno for control, and I have no feedback control system yet in place.  I am filtering with a capacitor in parallel with the load resistor as well as an inductor in series with the combination of those two.
I'd like to know why my oscilloscope measurement jitters from side to side and how much of a problem that presents to the quality of my sine wave?  Thank you!


texts: Improving signal communication over distance

texts: Knowing that Wi-Fi on 2.4 GHz has a good signal strength when there are 50 m between the access point and the unit that transmits the data. I want to transmit this data over a distance of 1.5 Kilometers, there is a line of sight. What can I do to make the communication over 1.5 km as good as the communication over 50 m distance?


texts: Why does it matter to adjust current if maximum power supply limit is not exceeded?

texts:
I found a "0-32V 0-5A Portable Adjustable DC Power Supply 110V/220V" (link available if I'm allowed to write it here) and I wonder why we should have to adjust current output (this device can also adjust current output) if the current load is not going to exceed the maximum of 5A? In other words, why not let the power supply provide as much current as is needed (up to 5A)? What's the point of adjusting it to lower ratings, say 3A or 2A or 1A etc.? This is something I don't understand. Is it just the "ripple" thing I read somewhere else?

By the way, I'm not an electrical engineer or something, just an enthusiast who ignores some more advanced aspects of the matter.

Thanks in advance for any explanations that will try to clarify things in a rather lay manner, as much as possible.


texts: ESP32wroom pull down 12V P-channel mosfet gate

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I am switching a circuit with a resistive and inductive load that is supplied with 12V using a p-channel mosfet. I already have the option to switch the p-channel mosfet with a mechanical switch (SW3) and have added a solder-jumper to an esp32wroom I/O in the design (JP3).

The p-channel mosfet gate is pulled high in the default state (Q19 does not conduct) and can ideally be pulled low with the switch aswell as the esp32wroom I/0 27. Since this is already on a pcb, i can only change the resistance of R23 and/or add another small component bridging the solder-jumper JP3.

Can I safely connect the 12V gate to the esp and use it to pull it low if i adjust the resistance/add another resistor at JP3? If so, what do I need to do ?

Clarifications to understand the image:

Load is between +BATT and GND
label power_switch is connected to esp32wroom I/0 27
JP3 is an smd jumper pad that would fit a 0805 component


texts: Downsides to terminating a line level audio signal into an amplifier without an output resistor

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I'm using a PCM5122 to output audio to a line level output as well as a PAM8406 amplifier.

If I connect the PCM5122 to the PAM8406 AFTER the output load RC filter, then there is noise introduced into the PAM8406 (exterior noise that can't be filtered).

What does work is connecting the output of the PCM5122 directly to the PAM8406 through a ferrite bead, into a 1uF DC blocking capacitor and into the 18k input resistor on the PAM8406.

My question is: Are there any potential issues that would arise from not using a load resistor?

Here is the output side of the PCM5122:

Here is the input side of the PAM8406:

Notes:

The PCM5122 output filter differs from the TI recommendations because the extra output load thwarts the noise present on the output (it's inherent to the system that the unit is being plugged into).
Output gain on the PCM5122 is 0dB right now. I may actually tune that further down to prevent clipping via the device gain registers.
The amplifier is set to 24dB gain as the system it's expected to drive an in-car telephone system (and must therefore be quite audible). The PAM works well in its current configuration, FWIW.


texts: Relay not switching immediately if mains off to battery like UPS

texts: Relay not switching immediately if mains off to battery like as backup power. I'm looking for zero cross SPDT relay switching for my project. please help. design is simple two power sources (mains and battery) and load will be at relay common pin.


texts: VIH of digital selection inputs for analog Mux when supplied with 4096mV - CD4051 IC

texts:
I will use CD4051BM96 part number, DATASHEET
On page 7 is shown specs of VIH. It shows VIH of 3.5V for 5V supply (this 70% of VDD), VIH of 7V for 10V supply (70%) and VIH of 11V for 15V supply (73.3% of VDD).
I will supply the IC with 4096mV, then the VIH would be around 70% of 4.096V? Around 2.86V?
This is cause I will supply VDD with 4.096V and will put 3.3V of processor on channel selection pins.
If it is supplied with 4.096V of VDD and is put 3.3V on any selection pin, will it recognize as logic high?
OBS: My input voltage on each mux input can go up to 4.096V also.
Regards.


texts: Amplify Square Wave with Simple Mofset Circuit

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I am a hobbyist.  I have a square wave being generated by a 5 volt Arduino.  (I tried a 555 circuit but I couldn't get it at an exact square wave.)
The Arduino square wave runs from about 2 or 3 volts to 0 volts.  I want to amplify that positive pulse to 12 volts with a mosfet (741) to pulse an electromagnet.   The electromagnet is a 12vdc and should run at or below 250 ma.  I tried the following setup but am getting a weird signal, kind of like a square wave with rounded shoulders at around 1 volt and a peak in the middle that goes up to about 7 volts.  I expected to see the exact same square wave that went in, but coming out at 12v+ instead of 3.  am I doing something wrong?

Edit:  Do you think the above circuit is correct?


texts:
Update:  I resoldered a new IC and everything works.

I have designed a charging circuit for a device that I am building. The circuit uses a MCP73831-2ACI/MC (datasheet).
These are the schematics:

The problem I am having is that the battery is not being charged. Very little current (0.5mA) is being drawn from the USB (VIN). When the USB is connected, the RLED will turn on, but very dim. However, the LED will stay turned on even if the battery is disconnected or connected. To me, this looks like the charger IC is not detecting the battery and therefore entering shutdown mode. This circuit is essentially a replica of what the manufacture provided in the datasheet.
There is a common ground plane on the board, however, VBAT and VIN are routed directly to their respective pins.
Why will the battery not charge? Does this have something to do with the rest of the device drawing current while charging?? Any help is much appreciated (and sorry if I missed any important info).
I have measured the following things on my circuit:
VIN = 5.18v
VBAT = 3.887v
VIN current = 0.5 mA


texts: USB-C Cable Doesn't Work but USB-C + USB A-C Converter + USB A-C Cable Works

texts:
As titled, I current have a tablet which has a single USB-C port running Android. I am trying to connect the tablet to my macbook transferring data. It works with any USB A-C with an adapter to convert USB-C-A when plugged into the Macbook port. I wanted to simplify my setup with a direct USB-C to USB-C cable, but could not get it to work. The tablet won't be recognized by Macbook. The tablet won't even show charing..

Could I understand why this happens?
How should I use a usb-c to usb-c cable in this case? For future, is there any specification a tablet should have to be able to use usb-c to usb-c cable?

Thanks a lot!


texts:
Using SMD to make the PCB smaller is an easy choice but I'm wondering if using mainly 0805 size is really worth it compared to 1206.

I don't want to store a mix of both.

These are some pro and cons, can you help adding some more to help deciding.

Soldering is a bit easier with 1206. (with my bad eye's all bits count)
Higher maximum power. 1/4W vs 1/8W --> lower temp. change for the same power.
PCB will be a bit bigger with 1206 (~10%??) but I'm not sure,  since you can easily run a signal under a 1206 saving 2 vias. The board is probably more determined by the big components anyway (I assume)
If µCurrent would use 1206 instead of 0805 wouldn't the PCB have the same size?
Price/Availability is the same now for 1% resistors, 0.1% seems to be better for 0805, will this stay this way or are they planning to fade out 1206 in the next years?

I would go for 1206 for all SMDs mainly for easier handling but I'm not sure if I'm missing something important?


texts: Differential Frontend Design for Mains Voltage Measurement

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I am building a digital wattmeter intended for measurements on AC power lines. I have went through a lot of application notes and example designs, and stumbled upon a slightly confusing motif recurring in a number of designs from Texas Instruments' TI Designs.

They employ a similar frontend for voltage measurement, where the mains voltage is first scaled down using a voltage divider. The scaled-down voltage signal is then taken as differential and passed through some low pass filter before being fed to a differential-input amplifier or directly to a high-resolution differential-input ADC.

Question 1

What is the purpose of the connection from Neutral to the reference ground, if it results in an impaired differential signal?

(simplified diagram of the input section from SimpleLink™ Wi-Fi® CC3200 Smart Plug Design Guide)

After running a simulation of this input circuit, I have found that the ground connection on the Neutral line renders V_SENSE- signal thousands of times smaller than the V_SENSE+ signal, and causes a non-180° phase difference between them, resulting in a suboptimal differential signal. On the contrary, if the connection is removed, V_SENSE+ and V_SENSE- signals are of the same magnitude and 180° relative to each other, creating a perfect differential signal.

What is the purpose of this connection from Neutral to the reference ground?

Question 2

What is the purpose of using a smaller value for R5? Why is it that the previous configuration use the same value for both R5 and R6? How do I
know when to use which?

(simplified diagram of the input circuit from Smart Plug with Remote Disconnect and Wi-Fi
Connectivity)

This is largely the same as the previous configuration. Apart from the differences in component values, the most intriguing difference is in R5, which is 100Ω as opposed to 1kΩ for R6. According to the document, the justification for the smaller value is to make up for the much larger impedance at V_SENSE+. However, simulation results show that the outputs are almost identical to those of the previous configuration. Moreover, the magnitude mismatch and phase angle problems still exist.

What is the purpose of using a smaller value for R5? Why is it that the previous configuration use the same value for both R5 and R6? How do I know when to use which?


texts:
I'm fairly new to electricity and just learning the basic concepts, and I wanted to ask a few questions:

One of the things that I couldn't understand from all I've read is the relation between Amperage and Voltage. Does certain voltage predict certain amperage across a wire? How is it calculated?

Voltage - From what I understand (which could be wrong), voltage can be understood as the strength in which electrons flow in a circuit. It is explained in few places as "The force that pushes electrons within a circuit". Volt is a measure of Joule/Coulomb - meaning - how much work can a group of electrons do.
In this video, he uses the water analogy to explain voltage in the following manner:

Voltage is like pressure in a water pipe. The more pressure you have - the more water can flow. The more voltage you have - the more can flow.

But as far as I understand, the more correct way to put it is:

The more pressure you have - the harder water flow. The more voltage you have - the harder electrons flow.

Isn't it?

Again the water analogy. The guy in the above video describes voltage like the pressure built when you put water in a tank. The weight of the water is what creating the pressure - so once you let water out, the pressure is constantly decreasing. The question is - is it the same with electricity? When I use a battery, does the voltage decrease as the energy is wasting?


texts:
I took a signal sum[8:0] in my code.  Further, I need only sum[8] in my code (M.S.B of sum). So I used the statement assign sum[7:0]=0;

It gave me the following WARNING after synthesis:

  WARNING:Xst:646 - Signal  < sum<7:0>> is assigned but never used. This
  unconnected signal will be trimmed during the optimization process.

Should I worry about it or ignore it?


texts:
I need to come up with something to convert a 5V digital output signal from a USB-1608G DAQ device with DIO to 24V digital output signal to reset the timer on a watchdog.  The watchdog timer will only draw around 7.5mA, just requires around 24V pulse for at least 1mS to reset the WDI period.  Any ideas on how to go about this or directions to go in?

I am thinking I will use an enhancement nMOSFET, with a Vth of about 2.5V.  I am not sure what the best transistor would be to use and how to really configure the circuit so I can get that 24V output.


texts: Creating battery pack with biased thermistor resistor network. How to ground if sensing externally

texts:
I designed a battery pack board for a customer that uses a multi-cell low-side (NMOS) protection IC. The protection includes OV, UV, OC, and OT/UT protection for the pack. The Overtemp and Undertemp protection is based on a bias network from the protection IC, with a thermistor tied to this network. The temperature is determined from a % of the bias voltage to this network, so it is independent of that bias voltage. This pack connects to another board via a 4-pin connector, one pin which outputs a 3-level voltage (HIGH, MID, LOW) such that the other board can detect OT, NORMAL and UT states.
However, because the protection IC disables the N-FETs when there is an OT/UT fault, I will lose the GND connection to the other board, making this tri-level digital signal useless, I think. So should I ground this differently and tie the digital signal output to the pack-side of the board, or keep it on the cell side?

To better understand what I'm doing in the schematic here:
U2:VTB and U2:TS form the thermistor bias network. Originally, I was going to buffer out the U2:TS voltage directly to monitor the temperature, but the U2:VTB bias voltage has a wide range (2.1-3.25V), so it's difficult to make a judgement about the temperature without having access to the VTB pin on the other board (the 4 output pins of the pack are BATT+, BATT-, TEMP_SNS, and BATT_SNS). So instead I opted to provide fixed voltage levels when the OT and UT thresholds trip.
U5 is a comparator which closely matches internal U2 OT/UT thresholds. U3 is a 4:1 mux that takes the output of the comparator and sets 50%VTB when all normal, VTB when cold, and GND when hot. Then this signal is driven through the buffer, U4 out of the pack.
Again, my question is more about the ground reference for this circuit which sits before Q1 and Q2 (cell side). However, the other board is ground referenced to the BATT- side (after Q1 and Q2). And I don't know if it will be able to sense the voltage output of that aforementioned circuit if the protection trips. When the protection circuit trips, the only connection to cell GND (not shown) is through the U2:LD pin, which is meant to detect when the load is removed in order to re-enable the pack protection FETs.


texts:
I had a very cheap solar panel + controller where the controller died.  To cheaply replace it I was going to build my own using some parts I had laying around and use a step-down (LM2596) to limit voltage from the solar panel into a battery and out to a XL6009E1 to boost battery voltage up to 5 volts to an esp cam.  Super simple circuit diagram as follows:

Solar panel == LM2596 == battery == XL6009E1 == ESPcam

while testing this circuit out on my bench power supply, before hooking the ESPcam up or battery, I noticed that at about 3.9 volts input on the LM2596 I am seeing 19 volts output on the XL6009E1! Checking on the output of the LM2596 I am seeing 3.2 volts.

testing circuit

Bench Power Supply == LM2596 == battery holder (no battery) == XL6009E1 == multimeter

Is this some limitation of the XL6009E1?

http://www.datasheetcafe.com/xl6009e1-datasheet-converter-xlsemi/

When I increase the voltage to >5V everything seems to smooth out, but will a dying battery fry my espcam?


texts: Output setting time for shift register (74HC595)

texts:
74HC595 Datasheet here

I want to implement ac phase control on a lot of channels (20-25) using esp8266 module. Since it doesn't have as many GPIOs, I want to use serial to parallel shift register. Since phase control requires precise and fast switching (fast as compared to the ac line frequency), I want to evaluate whether shift register is even a good choice or not.

For this, I want to calculate the total time required to set a pin's output to either HIGH or LOW. MCU running at 80 MHz.

There is a timing diagram given in the datasheet:

I am having a difficulty relating these things together and with the clock frequency of the MCU. Any pointers on how to calculate will be really helpful.

Thanks


texts: How do i build a laser based tachometer?

texts:
I want to build a tachometer that has to be somewhere around 1 meter from the rotating shaft.

I'm still to build a prototybe based on IR diode and phototransistor, but I'm afraid, I would get too much noise from other rotating parts/vibration even if stated 100mA IR LED current would be enough to give me enough light.

So, i thought, maybe i could build a cheap red laser based solution, but the problem is - what photo transistor should i use to detect laser that is bounced back from reflective strip on rotating shaft?


texts: Connect charger to device first or to power first?

texts: What reduces the chances of frying a device? Connecting the charger to the power plug first or to the device first?


texts:
I'm trying to route 10 DIP ICs on a single-sided PCB, but because of my available pcb space, I cannot fit all 10 ICs in one single row. Instead, I lined them up in three rows.

It seems that if I connect the VCC pin on every IC to the positive through some sort of jumper wire instead of a direct connection on the PCB itself then the odds of me being able to route the whole board to 100% rise significantly. Same deal with GND pins.

If I'm not mistaken, adding jumper wires introduces either inductance or resistance and too much of that can create undesirable results. The ICs I used are of mixed types: some digital like the 74HC, an op-amp, sound chip (ISD1700), DAC, etc.

I was initially thinking connecting jumper wires from +ve of battery to VCC and using maybe a couple 0 ohm resistors in parallel to minimize bad effects, but I'm not sure. The point is, I want to be able to route the whole circuit to 100%.

Which is better:

Connecting the VCC pin of every chip (or at least the digital IC's) to the +ve of the battery through a jumper wire and connecting ground directly to the -ve of the battery?

OR

Connecting the ground pin of every chip (or at least the digital IC's) to the -ve of the battery through a jumper wire and connecting VCC directly to the +ve of the battery?

and why?


texts: Why is my power supply putting out 3.85v instead of 5v?

texts:
I made a power supply using two 47uf electrolytic (aluminum, I believe) caps and a L7805CV 5v power regulator. I also added a 100ohm resistor and an led to vout. I'm using a battery pack of 4 NiMH AA batteries. The pack reads 5.43 on the multimeter with no load. When I hook up a motor to vout and ground, I get 3.85v instead of the expected 5v.

I'm wired up like so:

battery positive -> vin
battery negative -> ground
vout -> 100ohm resistor -> led -> ground
vin -> 47uf cap -> gnd
vout -> 47uf cap -> gnd

Here's a pic: http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs1169.snc4/154180_170665839624424_100000430264071_471279_1472098_n.jpg">

Any ideas?


texts: Is there a regulation that states which minimum ambient temperature range a commercial equipment must be operational? I.e., a mandatory range of temperature every industry must guarantee its products are operational?


texts: Network Identification - How to find R1 and R2

texts:
I've been working on this practice problem I found online.

So, from the graph I understand that \$R_{eq} = 2000\$ for the entire circuit. Since I want to find \$R_1\$ and \$R_2\$. To do this, I turn off the independent current source. As a result, the circuit becomes everything but the rightmost wire. To me it seems that \$R_1\$ and \$R_2\$ are in series. \$R_{eq} = R_1+ R_2\$. However, the solution says that \$R_{eq} = \frac {R_1}{2}+ R_2\$. Can someone explain how they're getting this?


texts:
Could someone please explain to me in as much detail as possible the schematic below. I'm really confused and would appreciate someone walking me through this.

What is the Rationale of connecting the componenets the way they are:

Why is there a resistor across the transformer secondary pins?
Why  are there two bjt's connected to each other?
why a zener and a diode in series?
what is the purpose of those 4 MOSFETs?
why are the 4 bridge MOSFETS are connected by an inductor?
why is there a mosfet connected to the right and left of the low side fets and the highside FETs?


texts:
Can anyone explain to me what is the logic behind high side RS flip flop, pulse generator, pulse filter from IR2101 internal structure picture ?
The input circuit is easy to understand and also the low side circuit.


texts: If the self-induced EMF in an inductor is 180° out of phase with source voltage, shouldn't they cancel out and net voltage should become zero?

texts: I know that inductor opposes the change in magnetic flux linked with it. In case of an ac sinusoidal voltage applied across a pure inductor, the emf induced across the inductor is equal and opposite in direction to the source voltage. So the net voltage should be 0. However when I connected a C.R.O across the inductor terminals, I observed only the source waveform, how is that possible, shouldn't it be zero. How can I see both induced emf and source waveform on the C.R.O


texts: Do I need a resistor between the microcontroller and the battery?

texts: I'm doing a university assignment and I need some advice. Do I need a resistor between the 9V power source and the microcontroller that uses 5.5V and 1mA? Also between a gyroscope sensor that uses 3V and 5mA?


texts: how to get a breakout made for module that doesn't have one?

texts:
I'm just starting out in this field and I got ideas for projects I want to build but I'm running into problems,  not so much with how to find the part I want or how to get it to work. but how to physically connect it. I see modules like this

and while I can find information on what pins I need to hook up what to, so the thing does what I want. I'm no where even close to being good enough as soldering to attach wires to modules like this. And most of the time I can't find an existing breakout board for the module I want to use. sometimes I can find one for other modules that claim to have similar functions but when I start reading though the details I find it really only shares the features I wasn't planning on using while the ones I did want aren't available.

So all that is me explaining why I need to ask is there service or something that I could use where I can get the module I want on a board? I don't mind having to either buy the module separately and sending it to them and then paying them to assemble the board.  or buying the module through them and paying extra for assembly. Or is there some trick to making them myself that I haven't heard about?


texts: Does output voltage of a boost converter depend on load current in CCM?

texts:
In the thread below, there are different opinions whether output voltage of a boost converter operating in continuous conduction mode (CCM) depends on load current or not.

Boost Converter Output Voltage dependence

Opinion 1: output voltage only depends on input voltage and duty cycle

Vout = Vin/(1-D)

Opinion 2: output voltage depends on input voltage, duty cycle and load current.

For example, as load current increases the duty cycle should also increase to make up the extra energy delivered to load.

So which one is right?
If output voltage doesn't depend on load current, then why do we need controller?

When the load current increases, the averaged inductor current should also increases. So how do we do that?


texts: Identification of 5 band Resistor from power supply

texts:
This Resistor is not functioning

The 4th band is Gold, I've read that means it's an exception.

The 3rd looks to me as silver, not gray, this is why I've added a picture.

I'd like to replace it, so I kindly ask what values should I look for in the replacement if I can purchase a resistor of a different value

The location is marked with R910

Edit:
band 1: Red
2: Red
3: (left this empty)
4: Silver
5: Gold
6: Gray

The results from here:

https://www.1728.org/resisclr.htm

2.2 ohms          5 % tolerance           1 ppm temperature coefficient

Is this correct?


texts: Need help identifying IC from Intel Mini PC PCB - top marking "1930 3614564"

texts:
I was looking into a blown up Intel Mini PC PCB (PIPO x8) and saw that a capacitor and a nearby IC were blown. I have no clue what the IC is or was for. Luckily I had a photo before it blew so I know the text on the IC, but could not locate any info on the IC. I suspect that they blew up because of over voltage (bad power adapter). IC said 1930    3614564.
Please help me ID what this IC does and a replacement for it.


texts:
I am designing a PLL.

Can anyone explain to me what happens exactly in a lock condition? Should both the reference and input frequency be same in that state? My input freq is 25MHz and my VCO is oscillating from 600 - 1Ghz for 0 - 1.8V. The divider divides by 2,3,3,2 to make it 25MHz at the input. Should the VCO be oscillating at 900MHz at the lock condition?


texts: STM32F4 host powering USB device using VBUS

texts:
I am trying to design an STM32F411 USB host. I will be connecting it to a USB MIDI device. The USB MIDI device I am using is AKAI Professional MPK Mini MKII which only has 1 USB port both for power and data which means that I need to power the device through USB.

From the STM32F411 datasheet, I have found some relevant circuit schematics:

However, I am unsure about the VBUS part. How am I supposed to power my USB device with microcontroller? My microcontroller logic is +3.3V and USB required +5V. Do I need to power USB device through VBUS pin on the microcontroller?

I have read somewhere that VBUS is used for sensing:

  The USB device is bus-powered, VBUS sensing is not mandatory (USB is always connected when the device is powered)

For my application, the microcontroller is going to be host only therefore I assume I don't even need to use the VBUS? Can I just connect the external +5V source to the USB VBUS pin instead?


texts: Recommended placement and routing of an RC Low pass filter

texts:
What are the recommended placement and routing techniques for the following RC low pass filter circuit:

I made an initial placement and routing that's shown below:

Actually it's randomly placed and routed because I don't have any recommendations.

Thanks.

Edit #1:

Thanks all, since no performance matters, I made a cleaner layout based on your suggestions that will also match the schematic placement:


texts:
Why is it preferable to use the built-in timer module rather than using assembly language coding to create delay loops?

I've gone through the entire "HCS12 Microcontroller and Embedded Systems" book, but cannot figure out why it is preferable to use the built-in timer module for the HCS12 microcontroller. I hope that someone can shed some light on this


texts: understanding the graphs of tau vs R in an RC circuit, and tau vs 1/r in an RL circuit

texts:
from my understanding, in a circuit like this one:

in order to calculate tau, you can use the inductor's value divided by the resistor's value. as the resistance (or impedance, in A/C). As R changes value, tau does as well. plotting tau and 1/R results in a linear realtionship. experiemntally, the time to reach  63% max current is also tau.

Similarly, in an RC circuit. like this one:

you can measure time to 63% max current and get tau. however, the linear relationship is now tau vs R!

I don't understand how that works exactly. I read something about Laplace transformations, but I would be lying if I said I understood them even a little. How exactly does the relationship between tau and R work in these cases?


texts: I'm looking for a sensor that would activate at a certain distance from the magnet or whatever would be signaling the location. The distance would range from 2-30cm and there would be obstacles (fabric, human parts,...) in between so that sound and light sensors would probably not work. I would want to be able to change the distance that would activate it. So if I'd set it to 25cm it'd activate when the two parts would get closer than that.


texts:
I'm still not sure about info I read on the internet. It said that to get the analog value also known as output bits of ADC use this formula:

Analog Value=(Analog Input*Max Value of ADC bit)/Analog Reference

Do you think the analog reference is the same as the voltage reference?
My real question is, do you think "Max Value of ADC bits" is same as 2^b where b is the number of bits?
I'm sure its maximum value of ADC bit must be (2^b)-1
I read in this article:

I cropped that picture from here, that article assumes a 10-bit ADC so it uses a maximum value of 1024, while I think it must be 1023. I think what they mean with 1024 is the possibilites not maximum value of an n-bit ADC.


texts: I have the following information in a problem: an input $$r(t) = 60u(t)$$, with u(t) being the unit step function, and a  transfer function $$H(s) = \frac{k_1}{s^{2} + s + k_{1}}$$, where k1 is a variable constant from a controller. I want to find the output y(t) but so far the farthest I can get is $$Y(s) = H(s)r(s) = \frac{k_1}{s^{2} + s + k_{1}} * \frac{60}{s}$$ Supposedly I can break this up into a partial fraction decomposition with three terms but I have no idea how to proceed because of the k1 term. Any help would be greatly appreciated


texts: Derivation of Parasitic capacitances in MOSFETs using Cadence Virtuoso

texts: I have to design a circuit to derive the n-channel 180nm MOSFET gate-to-drain, and gate-to-source capacitances in Cadence virtuoso. I have little experience with the software, if someone could describe what the procedure is, that would be very helpful.


texts:
This seems like it should be a really easy one, but I'm having trouble finding a clear reference or explanation for it.

According to Wikipedia, line level has a peak around 0.5V, but I can't tell if that's GND to 0.5V, or -0.5V to 0.5V, or something else entirely. Which is it? (EDIT: Nevermind, it's now clear that it's the second case. Here's a scope capture linked from the Wikipedia page.)

The reason is that for switching ICs (mux, pot, etc), you need to have a V+..V- which exceeds the range of the analog signal, eg from MCP42XXX datasheet p15:

  For linear operation, the analog input and output signals must be in
  the range of VSS to VDD for the potentiometer...

Since the line level audio goes below GND, I assume I need a charge pump or virtual ground arrangement to use an IC such as the MCP42XXX. Is this so? Which is the recommended approach?

Edit: I discovered the answer to the first part of my question, but the second part remains relevant.


texts: What connector is similar to U.FL but has no pin?

texts:
I am trying to identify this connector style:

Look at the two RF micro-coax connectors on the left, just next to the PCB antennas.  They look identical to U.FL or IPEX but have no central pin.  What are these, and what are they used for?

This is what U.FL looks like for a comparison:


texts:
i have a question for my class but i cannot answer it, any help to understand this question will be more than grateful.
Why it is so important to minimize the commutation loop inductance of a half bridge especially in case of WBG transistors?
Thanks all


texts: Does a boosting circuit reduce battery voltage without any load?

texts:
Suppose I am trying to boost the voltage of my 3.7V Lipo battery to 8V using a boost converter (MT3608 module) and lighting up some LEDs.
Does the voltage of the battery reduce just because of the boosting circuit, if no load is connected at the output(which is 8V) of boost converter?
Does the boosting module play a role in reducing the battery voltage when no load connected, or does the battery drain as usual in the same way with or without a boosting circuit when no load is connected?
I'm doing it practically now. My lipo battery voltage is 3.7V, I boosted the voltage to 8V (without any load) and left it to check whether boosting circuit reduces the batery voltage. In 1 hour battery voltage has reduced to 3.67
What is the reason for this and how can I avoid this problem, since suppose say if we are trying to make a PCB, Lipo battery will always be connected to boosting circuit and it can drain the battery overnight.


texts: Raspberry Pi - Controlling Multiple RGB Led Strip

texts:
I am able to control an RGB LED strip using Raspberry Pi, using 3 x TIP120.

However, I would like to add multiple strips, maybe about 7 to 10 RGB LED strips. I will use 12V 30A power supply.

I am wondering why the light is not so bright when I connect 2-3 series of RGB LED strip.

Do I need to use 3 x TIP120 for each RGB LED strip?

Any suggestions is appreciated.

Thank you!

EDIT:

Image from http://popoklopsi.github.io/RaspberryPi-LedStrip/#!/

I used that tutorial related to this question.


texts:
Let's consider an interface between a simple microprocessor and a certain memory. For instance, let's assume that the microprocessor drives the address bus, a read signal, a write signal, and that the data bus is a bidirectional signal, which can be driven by the processor or by the memory depending on if it is doing a reading or a writing.

In that case, it is necessary that after a reading, the memory puts its output on data bus at high impedance, and that after a writing, the processor puts its output on data bus at high impedance. Both operations to avoid conflicts.

But what if for instance we have a data bus for reading (driven by the memory) and a data bus for writing (driven by the processor)? Is it necessary (or anyway better) that the processor puts its output on the databus he drives at high impedance after a writing operation?


texts: DIY 75ohm to 50ohm impedance matching circuit to work at UHF frequencies around 470MHz to 600Mhz

texts:
I have a transmitter circuit that has 75ohm impedance with the F-type connector. I need to connect this device to a 50ohm impedance power splitter/combiner with SMA type connector. The transmitter device is operated at UHF frequencies around 470-600Mhz (nothing over the air, all testing is done via cables). Is there a DIY solution to build a impedance matching circuit which can work in the above mentioned scenario ?

Edit : The transmitter's output power is around 26dBm to 30dBm, which is very low power.


texts: 3 phase motor running on single phase using steinmetz delta connection

texts:
How do 3 phase motors manage to run on single phase power using the Steinmetz delta connection with a single capacitor? I thought capacitors only shift the phase angle upto 90 degrees, whereas 120 degrees phase shift is needed. Can someone explain this mechanism in detail or provide reference where I can read up on this particular topic?

I also need to understand how to calculate the capacitance needed to run a motor in this manner.

Is there a way to possibly calculate the power loss due to this method? Or do motors just provide 1/3 of its power when running on single phase?


texts: Transformer Power on the Primary and the Secondary

texts:
I am confused as to the power of the primary and the secondary of a transformer.
An elementary textbook says the power on the primary and the secondary are equal (and therefore there is no power gain or loss, in the ideal case) because
\$V_PI_P = V_SI_S\$,
but it seems to me that it is ignoring phases. The power is \$VI\$ only when the voltage and current are in phase. In actuality the power on the primary is \$V_P I_P \cos\theta_P\$ where \$\theta_P\$ is the phase difference between \$V_P\$ and \$I_P\$ and the power on the secondary is \$V_S I_S \cos\theta_S\$, where \$\theta_S\$ is defined similarly. So the above equation holds only when the phase difference between the voltage and the current are the same on the primary and the secondary (\$\theta_P = \theta_S\$). Is this always the case?
What I'm also not sure is what is meant by 'power.' Is it 'power consumed'? An ideal transformer cannot consume power because it is purely inductive. If you are talking about a resistive load on the secondary, then there would be another resistive load on the primary, and so the power consumed is doubled if the loads are equal (in the case of 1:1 transformer)? Well, I'm not sure how general the situation I'm talking about, and I might be missing something as well. Clarifications will be appreciated.


texts: Spartan 6 FPGA IO changes state disregarding design

texts:
Hello I have made Spartan 6 board and now I'm trying to get it work, I have successfully managed to get programming of SPI flash working so I can upload bitstreams, but I have problem that some of IO pins doesn't stay at their desired state.

For example I have 4 IO used to control relays of attenuators (used in oscilloscope module) and when I set state at reset it holds it for 40 nanoseconds and then it gets back to zero.. I even have communication protocol in which I can set IO state programatically through software and it change state but again only for 40ns or so then go back to logical zero.

In simulation everything works as expected, also post par static timing shows that my timing constraints (60MHz clock of FTDI's FT245 and 150MHz clock of ADC oscillator) were met. I have triple checked my UCF if I have not used wrong pins but it's all the same.

I was thinking that I am somehow reseting design (I use FTDI for that) in FPGA but it's not the case because I have hooked scope on reset pin of my design and it didn't triggered. Also other things in my design works, for example I can successfully set reference voltages of ADCs (controlled by DAC)  values through serial interface (which is slow - 100kHz) so reset that would kill IO state after 40ns would also stop setting of DAC.

Do you know what could force FPGA to disregard design set IO states?

//edit: adding code:

this is part that sets IOs: (the led1 faintly blinks when this happens)

              when SET_ATTENUATORS =>
                led1 <= '0';
                adc1relatt <= commandData(71);
                adc2relatt <= commandData(63);
                state <= IDLE;

and this is IDLE state:

             when IDLE =>
                ft245rw <= '0';
                ft245strobe <= '1';
                ft245dataWaitIn <= '0';
                if (to_boolean(ft245busy) and (ft245oe = '0')) then
                    state <= READ_COMMAND;
                    ft245strobe <= '0';
                else
                    state <= IDLE;
                end if;

and this is reference voltage setup state:

              when SET_VREF0 =>
                led1 <= '0';
                dacVrefTopA <= commandData(72-1 downto 64);
                dacVrefBotA <= commandData(64-1 downto 56);
                dacVrefTopB <= commandData(56-1 downto 48);
                dacVrefBotB <= commandData(48-1 downto 40);
                if to_boolean(dacBusy) then
                    dacStrobe <= '0';
                    state <= SET_VREF1;
                else
                    state <= SET_VREF0;
                    dacStrobe <= '1';
                end if;
            when SET_VREF1 =>
                if to_boolean(dacBusy) then
                    state <= SET_VREF1;
                else
                    state <= IDLE;
                end if;

In this state the led1 also only faintly blinks (it should stay on, not blink) but also only other state that I change state of LED is reset which couldn't happen because that reset would also reset DAC module which would prevent DAC setup module from setting DAC values (it successfully does that).


texts:
I'm trying to make an EventQueue call inside a method attached to a Ticker. The EventQueue, and context thread is declared within the class which holds the method in question. A simplified example:

    class EventHandler
    {
    public:

    EventHandler() {

      t.set_priority(osPriorityRealtime);
      t.start(callback(&queue, &EventQueue::dispatch_forever));

    }

    void handler() {

    //Do whatever

    queue.call(&exobj, &ExampleObject::update, 0x0); //call update within user context, with state exobj, and parameter 0x0

    }

    private:

    ExampleObject exobj;
    Thread t;
    EventQueue queue;
}

Main File:

int main() {
    EventHandler eventhandler;
    Ticker tick;
    tick.attach(&eventhandler, EventHandler::handler, 1); //call handle periodically
}

On compilation, the following error is displayed:

Error: Expression preceding parentheses of apparent call must have (pointer-to-) function type in "extras/mbed-os.lib/events/EventQueue.h", Line: 2883, Col: 14

Can anyone explain this? I have followed the correct syntax for making calls on the EventQueue


texts: Simulating mosfet with body bias ltspice

texts:
I am trying to simulate a simple mosfet circuit with body bias. I am using the command
.model NMOS NMOS (kp=100u Vt0=0.8 phi=0.7 gamma=0.4 )

to set up the parameters and I have set the body bias to 3 using a voltage source.
The new Vth calculated by spice is 4.65e-01V but the one I calculated theoretically is  1.23V. What am I doing wrong


texts: How to automatically allocate a page of flash for in-application storage of settings

texts:
I've been using the LPC8xx range of Cortex-M0+ MCUs quite successfully. One difficiency: these don't have inbuilt EEPROM (to preserve settings across power cycles etc). However there is a work-around: using the in-application flash programmer, a page (64 bytes) of flash memory can be erased and rewritten.

I used this example:
http://www.lpcware.com/content/forum/eeprom-emulation
which works.

My question: this example hard-codes the address of flash to which it will to write to. This seems very dangerous to me. Is there a way to allocate a 64byte aligned block of 64bytes in the flash memory space so that I can be sure it's safe to write to?

(I'm using LPCXpresso / GCC)


texts: I want to use thermal paste for improving the thermal resistance between a semiconductor and a cooling element. But when I got it out of the tube, it was party transparent/fluid, and partly white/pasty. Can I nevertheless use it, or should I remove the fluid, or should I rather buy completely new paste?


texts: What happens to a transformer if the supply side is shorted?

texts:
Suppose I have an industrial plant, where a switchboard is fed through a transformer. The switchboard have only "passive" loads, i.e. they don't contribute with short circuit currents.
If there is a short circuit on the switchboard feeding that transformer (on the grid side), my intuition tells me that the transformer would be demagnetized (disregarding remanent flux), thus energy must go from the transformer to either the secondary or primary side. Since current can't immediately change in an inductor, I think this energy should go to the secondary side.
My simulations show this behavior. As the image below show, there is current/power flowing for about 2 ms (the results on the primary side is identical, so I haven't included it). However, I'm not sure if this is the correct physical representation or a result of inaccurate mathematics. The minimum integration step I can select is 1 ms, so it might be a result of that (I think).

The reason why I doubt the results is because the exact same current flows from the shorted bus and in to the transformer on the primary side. Investigating the results on both sides of the transformer, I see that the exact same amount of energy goes in and out after the primary side is shorted. This tells me the transformer is not demagnetized.
Now, as we all learned in kinder garden, current in must equal current out, so how could I expect something different? Well, it's not really true in all situations (you can for instance charge a capacitor). I know the energy store in a transformer is magnetic energy, not electrical.
Still, there is something here that doesn't seem right to me. I appreciate any input!
Thanks!
Update
It is possible that my explanation has not been good enough. The short circuit I'm talking about is a fault that occurs after a certain time, 3-phase, line-line, line-line-ground or line-ground.
Here's a part of the single line diagram. I don't have any "justification" for why the delta-star connection is relevant for the analysis (I don't think it is, it's simply how the system is designed). There can be many reasons, elimination of zero sequence currents for one, but this shouldn't be relevant for this quesiton.
The diagram below is how the transformer is represented in my simulation tool. I can't "show" how the circuit is shorted. The way it is done is I add an "event": "Create a (3 phase / Line-Line / ...) fault after 3 seconds. Then I can see the system response as a result of this event.
I would think the general behavior of the transformer is independent of the topology, vector group etc.


texts: Why is a capacitor used to protect CMOS chips?

texts:
I am studying digital electronics. A book says that "use a 0.1 μF capacitor between Vcc and ground for each IC".

What does this mean?

Why can a capacitor protect CMOS chips?

Does it mean that a capacitor should be added like in the figure?

update (7/21/2016): okay, maybe I was confused with the meaning. A chapter of the book was talking about static protection for CMOS chips and for an experiment it mentioned the quotation with a footnote.
The footnote says, "In keeping with standard practice, capacitors are specified, particularly with CMOS devices, to return switching current 'spikes' to the source through the shortest possible path"

So, I thought a capacitor should be used to "PROTECT" CMOS chips.

As I said, I am studying digital electronics. I don't know about decoupling capacitors. So still I don't know if my question is duplicate :(

simulate this circuit – Schematic created using CircuitLab


texts: Does my Sequence Recognizer detects this pattern?

texts:
Question: build a circuit detects the two sequences 0101, and 1010 (maximum possible overlap of 1 bit). The circuit has one input X (received), It also has a active-low asynchronous reset and clock inputs.

1) Obtain the state diagram of the circuit using minimum number of states, and specify whether it is Mealy or Moore.

my answer is this:

is it correct? how do I know it's a Mealy or Moore, and what is the procedure to make it Moore or Mealy?


texts: Can I guess the Rds(on) at 3.3 V from this MOSFET datasheet?

texts:
I ordered some MOSFET switch modules. Because they were advertised as "for Arduino" and "Voltage: 3.3V, 5V", I assumed they had chosen a decent MOSFET for the job (like the IRLU7843 or at least the IRLZ34N). There is no additional circuitry on the modules.

Now I see that they use the IRF520, which struck me as odd, as I remember them to be a bad fit for a microcontroller project.

Here's a datasheet. Is there a way to guess the RDS(on) at VGS = 3.3 V or 4.5 V from it?


texts: Rotating POV LED Cylinder Using Addressable RGB LED Strips

texts:
My son and I are trying to build a somewhat large Rotating POV Cylinder (or Globe) making use of ready-made Addressable RGB LED strips (WS28011 or LPD8806?). After some browsing, we found that many of the stuff in the web make use of Arduino and similar micro-controllers. They also create their own codes or programs.

Since we are not that technically competent, we would  prefer to make use of our windows-based PCs or the T1000 controller for the LED strip, if this is possible. If not, my son knows a bit of C+ and Python. We would attempt to play video or a series of images to the Rotating POV device. We are considering to use a Raspberry Pi since I intend to show videos in the POV and make use of a large number of addressable RGB LEDs.

My questions are:

Is this project feasible?
Could the controller just play one line of pixels of an image in a portion of a microsecond while it is rotated to produce the desired image? Most of the POV samples in the web are only several pixels high while I am thinking of something that is around 120 to 240 pixels high.
What readily available micro-controller or micro-processor do you suggest and why?
What Addressable RGB LED Strip should I use? We are considering the WS28011 strips since they have as many as 144 LEDs per meter.
There is a T1000 controller. Can this be used?
Are there ready-made applications that will allow to display videos in the Rotating POV Cylinder (such as the LedEdit for LED matrices)? Perhaps we could acquire the output of the LedEdit app and divide these into columns.

Below is an image of what we are trying to achieve.

We would appreciate your comments and feedback. I would just want my son (and I in the process) to learn from something that seems to interest him.

Regards,

JB


texts:
It is said that vector sum of flux and torque current equal to total current drawn by the motor but there are also some currents flowing due to copper losses and rotor leakage inductance. In my opinion, the total current must equal to vector sum of core losses current + torque current and rotor leakage inductance current + flux current ? Is my opinion correct ?
One more question, if we control the motor via contactor , can we say that vector sum of flux and torque current equal to total current drawn by the motor ? I mean if I want to learn how much percent torque I use for a load and I know the flux current of motor which is controlled by contactor. Can I use the formula above to first calculate torque current and then torque percent ?


texts: Video & image processing in Spartan-6 FPGA

texts: I'm very new to FPGA.  I got a Spartan-6 from Digilent. As my final year project I want to do image processing through it.  How can MATLAB & Simulink be used for this?  How should the camera be connected to the board?  Through HDMI or USB?


texts: How much current does the Eltako ER12-001 need to switch the output?

texts:
The Eltako ER12-001 seems to be an interesting relay.

It has an integrated electronic circuit to operate a bistable relay, while acting like a normal one. The control current can be either AC or DC, but I couldn't find any info on the current required to switch the relay.

I have to make sure that my open collector output can sink enough current to switch this relay. Where can I find the information needed?


texts:
I am building high-speed (10-20ns on BC847-class transistors) digital "buffer"/"inverter" out of BJTs.
Scheme is attached.

While I can prevent saturation of low-side BJT by adding Schottky diode, it's not going to work for high-side. Any hints except decreasing resistance of base-resistor?


texts: What determines the voltage requirements of an IC?

texts:
This is more of an acquiring more knowledge question.
I have used a few ICs, such as the 741 op-amp, AND, OR, NAND gates, etc.
I have also used a few micro-controllers like the atmega32, atmega328, etc, which are made of the ICs.
However when the micro-controller are being manufactured what determines their operational voltage?
For example, an atmega chip requires 5V but why is it 5V, why couldn't it be designed to operate at low-voltages like 3.3V or lower. What component determines the operating voltage when these micro-controllers are being designed, also what determines the operating voltage of that component? Please don't say the datasheet...


texts: H-Bridge MOSFETS getting hot with no load

texts:
I have the following circuit:

The circuit is working fine, but the problem is that when there is no load, the IRF9540 are getting hot. When they are in load, they are cold. For sure, I think it's a problem with the gate-source resistors.

I measured the voltage drop between G-S on the IRF9540 and I have the following values: -3.5V in no load and ~-11V in load.

I don't know how to tune the circit to remove this no-load heating, so I'm asking for your help. Thank you !


texts: Why PWM pin needs intermediate MOSFET TC4420CPA to drive IRFZ44NPBF in this circuit?

texts: Why not directly drive only with the low-pass filter? (FYI, this circuit is for constant current load)


texts:
I am using an Arduino Uno and TC1602 LCD display to write from MCU to the module. I have checked the wire connection for a lot of times, but still only backlight no text. So I am wondering whether there is possible that the display function has been burned out? Is there possible that the backlight works well but the display text is damaged?

I have it connected as follows from the Arduino LiquidCrystal page:

And the code taken from the same page is as follows:

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis()/1000);
}


texts: Why would my Lattice IceStick stop working when configuring the PLL?

texts: I'm using a Lattice FGPA IceStick with the newer IceCube2 programming environment and the Diamond 3.0 programming tool. The 'iCEstick LED Rotation' example runs OK but when I attempt to enable the PLL, the example stops working. By 'stops working', I mean that upon download the LEDs don't blink and appear to be in an intermediate state as if configured as inputs. The problem remains after removing the PLL. No help found on Lattice's site.


texts: Why are the values I'm getting through a capacitive sensor decreasing as the resistance gets lower?

texts:
I'm currently messing around with "capacitive sensors" by trying to light an LED using an Arduino. My capacitive sensor that I am using is just made up of an Arduino, three wires and a resistor. My setup is simply two wires hooked to an Arduino and both ends of a resistor, with the third wire connected to the resistor on one side, and nothing on the other.

When I am using a 1 megohm resistor, I am getting values in the range of 2700 ~ 2800 when I grasp the exposed end of the wire with my fingers. However, when I try switching the resistor to one with lower resistance (10,000 ohm), I am only getting values of 60 when I grasp the exposed wire, and I get values of 0 when I use a 220 ohm wire.

An illustrative example:

.............
|           |--------- <-- wire
| ARDUINO   |        |
|           |      Resistor
|           |        |
|           |--------- +++++++++++ <---- Exposed wire which I grab
.............

Should I not be getting a greater value by using a resistor with less resistance as that would allow more current to flow through? Yet, the inverse is happening where the values outputted from my Arduino decrease as I lower the resistance and increase as I increase the resistance.

Why is this so?


texts: Why are the high voltage overhead power lines with the same potential being isolated?

texts:
Photo #1

Photo #2

Photo #3 - A zoom of Photo #1

Photo #4 - A zoom of Photo #2

I shot these photos while travelling in a highway. In each line-group has three separate lines. I think that the three lines in each group carry the same electrical potential (if not, could they be so close to each other?).

Why are the three lines in each group isolated from each other?
Is there an electrical reason for this?


texts: Output voltage function (circuit-analysis)

texts:
What will the function of the output voltage be?

My work, and am I right?:

$$\text{V}_{\text{out}}(t)=\frac{\text{R}_9\text{V}_{\text{in}}(t)}{\text{R}_{10}}+\frac{1}{\text{R}_{11}\text{C}_1}\int\text{V}_{\text{in}}(t)\space\text{d}t+\text{R}_{12}\text{C}_2\cdot\frac{\partial\text{V}_{\text{in}}(t)}{\partial t}$$


texts: Microwave - Standard Intermediate Frequency?

texts:
VHF/UHF receivers use one of a few standard intermediate frequencies. Is there a similar set of standard intermediate frequencies for microwave (around 3GHz) receivers?

As I understand it, the choice of IFs usually comes down to what filters are available and how easy it is to create an LO at the appropriate frequency. Is that the case for microwave receivers as well?


texts: Is there a temperature sensor which triggers voltage output upon breaching a temperature threshold?

texts:
Is there a temperature sensor which will output a certain voltage if the temperature is below a certain degrees? e.g. Output 5v if temperature is < 0°C and output 0v if > 0°C.

I'm trying to figure out how to detect when a temperature drops below freezing and I'm unable to utilize 1-bit bus, single bus and one-wire setups for temperature inputs. Only a "1" or a "0" digital input is usable.


texts:
For a project, I would like to connect a cheap PCB antenna from Molex to a SMA female connector. One of the antenna is this one:

Molex 146220-0100:
http://www.molex.com/molex/products/datasheet.jsp?part=active/1462200100_ANTENNAS.xml

Instead of a exact description of the connector of the antenna, the specs only state that it fits on a "Microcoaxial RF" connector, described as: 50 Ohms, MCRF, PCB Vertical Jack Receptacle, SMT, 1.25mm Mounted Height. Shown here: http://www.molex.com/molex/products/datasheet.jsp?part=active/0734120110_RF_COAX_CONNECTORS.xml

Is the plug on the antenna a proprietary connector from Molex?

Or in the other case, whats the right name of the connector I have to search for?

My goal is to find an adapter from the connector of this antenna to the SMA female connector on the board I use.


texts: LDO regulator below minimum input voltage

texts:
I'm designing a circuit that will run from 3V battery. The battery can get as low as 2V and I want to use it as much as I can.

I'm using a PIC24 that operates with the integrated regulator for VDDCORE disabled with a VDD from 2.0V to 3.6V but VDDCORE goes from 2.0V to 2.75V max, so I can't power the microcontroller directly from the battery as I will be exceeding the VDDCORE allowed voltage.

I'm planning to use an LDO as the MCP1703 with an output voltage of 2.5V to power the microcontroller VDD and VDDCORE. My current consumption won't be higher than 50mA. My question is, when the battery voltage goes below 2.5V (plus the dropout voltage) will the regulator act as a switch bypassing the input voltage to the output plus a dropout? How high would be the dropout?


texts:
I'm new to simulations on LTSpice with op amps (and LTSpice in general).

I've been trying to simulate a Sallen-Key low pass filter and the simulation is nowhere near my calculations plotted with \$Mathematica\$.

This is what I did:

And this is what it yields:

But http://sim.okawa-denshi.jp/en/OPstool.php simulator and also Mathematica yields this:

Which looks alright.

Thanks you in advance!


texts: Adjustable Voltage Regulator that operates in the uA region as a Precision Current Regulator?

texts:
I've been looking at all sorts of voltage regulators to suit my needs, I'm arranging an adjustable voltage regulator in such a way that I'm actually using it as a precision current source. Turns out I can't paste an image, but you can see the "Precision Current Limiter Circuit" on pg12 of the LM317 datasheet here: http://www.ti.com/lit/ds/symlink/lm317.pdf

The idea is that there is a fixed voltage (enforced by the regulator) between the adjustable pin and the output pin. A resistor between those two nodes determines the output current.

My question is this: Is there an adjustable voltage regulator I can use at this setting for an output current of ~150uA? I haven't been able to find one that operates in this way below about 2mA.
This is the only way I know of to make a precision current regulator.

EDIT: here is a good image of a voltage regulator being used as a precision current source: http://diyaudioprojects.com/Technical/Current-Regulator/1-Amp-Current-Regulator-Scheamtic.png.

This is what I am trying to achieve but the voltage regulators don't operate as intended at such low current and so I haven't been able to achieve a regulated current regardless of the load.


texts: Should we use asynchronous inputs in Moore blocks and synchronous in Mealy blocks?

texts:
Consider we have two n-bit counters CNT_A and CNT_B two n-bit unsigned comparators CMP_A, CMP_B and two n-bit binary numbers N1, N2. The counters have two inputs C, L for synchronous count and load respectively such that:

when C=L=0 counter holds its current value
when C=1, L=0 the counter increases by 1
when C=0 L=1 the counter synchronously load an nbit number given by the user to its input line INPUT
when C=L=1 the counter decreases by 1

The counters also include an asynchronous reset pin RESET (the counters reset to 0 when RESET=1) and an asynchronous ENABLE pin that either enables (ENABLE=1) or disables the counter (ENABLE=0).

Consider we want  to build the following digital circuit:

CNT_1 counts from 0 to N1 (0 to N1 clock pulses)
CNT_2 counts from 0 to N2 (N1 + 1 to N1 + N2 clock pulses)

and this process is repeated again and again.

Let x be the == output of CMP_A and y be the == output of CMP_B. Note that the comparators are connected to their respective counters CNT_A, CNT_B. Let Q(t) denote the state of the controller FF at time t.

For instance, consider the following two implementations:

Set ENABLE <= 1 and RESET <= 0 and use the synchronous inputs L,C to implement the counters.
Set L = 0, ENABLE <= 1 and use the asynchronous pin RESET to reset the counters.

When designing ASM charts for each implementation I came across this observation:

Asynchronous pins (case 2) ought to be of Moore type (RESET pins have values Q(t) and Q'(t) for the two counters) while the L pins (case 2) must be of Mealy Type. Besides this, the synchronous pins L1,L2,C1,C2 ought to be of Mealy Type in case 1.

Is my assumption true, namely asynchronous pins must be implemented as Moore outputs, and synchronous as Mealy ones?


texts:
I work in the field of telecare and advances are helping us keep the elderly and vulnerable out of residential homes/hospitals and allowing to retain their dignity and independence by staying in their own home.

The one thing that is missing in my "arsenal" of equipment is a sensor that will track when the wearer moves out of the property or range of the central control unit.  Kind of like the prisoner tag systems, but less intrusive.  Obviously I don't want to tag the elderly and this would only ever be used with consent.  I would also like the option of many tags being monitored as we couldn't always guarantee that they would take their phone, keys or bag (or clothes sometimes!)  Ideally the "tags" could be small enough to be sewn into clothing or added to small bracelets or chains.

I've looked into RFID but the range or cost always becomes an option.  What other things can I look at to help?  GPS would be great to find the wanderer but again size of the "tag" would become an issue.


texts: What can't the ATtiny do that the Arduino can?

texts: Inspired by this Make Magazine youtube video, I would like to use the ATtiny chips instead of the Arduino for most of my projects. The video author warns that some Arduino functions won't work on the ATtinys. Is there a complete list of what is and is not supported?


texts:
So with the following circuit (currently studying for an exam):
I am able to get V- just through the voltage divider composed of 2R and R at the non inverting terminal. However, once there, I am unsure of how to get Vout just because of the 3R resistor going from Vout and ground. Can I treat the feedback loop resistor, R2, and the 3R resistor, as a voltage divider that gives me Vout in terms of V-? If so, then what about the current that exits the opamp?


texts:
I have a simple circuit using a 555 timer as an oscillator to output a 12v tone to an intercom system.  I'd like to make a delay circuit that will turn off the output of my circuit after a delay.

Tone output of first circuit turns on timer while passing through to intercom system for approx. 30 seconds
Delay circuit turns off tone for a set time approx. 2-5 minutes.
Tone passes through to intercom again for 30 seconds and then off again.

Is this possible?  Using an oscillator output to run another timer circuit?  Will the charging circuit cause the volume of the tone signal to drop as the timing capacitor charges?


texts: Identifying a capacitor with marking K1G 103J

texts:
I need help identifying a throw-hole capacitor, orange/brown color, with markings:

`K1G`
`103J`

I suspect that it is a KEMET part, but they might have obsoleted the part, as they have no posted datasheet for it. Anyone?


texts: LM311P op-amp strange behavior in comparator mode

texts:
I'm trying to build a schematic which will turn on a relay in case motorbike battery voltage will reach some level. I've ended up with the following schematic.

simulate this circuit – Schematic created using CircuitLab

Input voltage can vary from 12 to 14.5 V. So the plan was to compare half of the input voltage from the 1:1 divider to the Zener voltage, which is always 6.8V. So when input voltage exceeds 13.6 volts, the transistor should energize relay coil. However there is a hysteresis in relay switching, from 10.1 to 12.8 volts. It switches on at 12.8, and then releases at 10.1 volts. What is the reason of that, and how can I adjust hysteresis loop to my needs?


texts:
I need to calculate the voltage at node A at the below circuit. Please tell me whether my approach is right

So, I am assuming that the 1000ohms in series with the voltage sources as internal resistances.

Current through the 500ohm would be, I = 10/500 = 20mA

But we need to consider the internal resistance of 1000ohms right
So, terminal voltage, Er = V - IR, Er = 10 - (20mA)*(1000Ohms) = 10-20 = -10V ?

What am i doing wrong here?

Please let me know


texts: How do I connect an avalanche photodiode to an Arduino Uno?

texts:
I understand that there was one other question regarding avalanche photodiodes, however I am looking more for connecting my APD to a microcontroller (Arduino).

https://www.edmundoptics.com/testing-detection/detectors/avalanche-photodiodes/

As I understand, the middle leg is the "ground" to the casing, while the other two are anode/cathode. However, since my Arduino's ground and anode are technically  the same, how should I connect them? Or should the ground be wired to something else entirely?


texts:
I have a small project and I'm interested "upgrading" to a more produce-efficient design. Please note I'm no electrical engineer.
I want to move a small servo (like this one http://www.hobbypartz.com/topromisesg9.html) 170 degrees on one tactile button hit, and all the way back when hit again. The whole thing should be powered from a 5V car USB charger.

I've implemented my prototype using an ATTiny85 (way overkill..) programmed using Arduino IDE, manual PWM (delaymicroseconds()) and one byte of EEPROM.

I'm looking for the most low-cost (and on secondary importance - lightweight and small) solution for this application. I don't expect any design schematics just ideas on implementation. There are no further "restrictions".

Also if there is a better way than servos for the same usage (still focus on low-cost and wieght), I'll be pleased to hear about.

Thanks for answerers.


texts: Have 'natural response' defined clearly?

texts:
some textbook says it is zero input response(response with only initial energy stored). But in other contexts,like response of an RC circuit with only step input (no initial energy) ,the transient part of the solution is called natural response.(I assume voltage across capacitor as response).Please clear my confusion.

This section is from Engineering circuit analysis by Hayt

Now this is from an MIT Lecture

Link of this Lecture Natural Response


texts: Overlay plots from PSpice - SIMetrix or SIMetrix to PSpice

texts:
I wanted to verify the accuracy of a identical model which I modelled, between PSpice and SIMetrix simulator

I ran model in Pspice and SIMetrix separately and probed required nets (net names are identical in both the simulators)
Saved the file of SIMetrix in .dat format and appended in PSpice as shown

So I tried another approach to overlay in MS-EXCEL or Libre office and exported the simulation plot in .CSV but I couldn't find option to export SIMetrix plot in .CSV or any other format.

Is there any different approach to do this exercise?


texts: Wiring Considerations for numerous LED's

texts:
I'm working on a hobby project where I'm going to need to wire up 40-80 (not sure exactly how many yet) LED's of various colors. Only 10-20 of them are going to be on at a time. This is going to be a hobby project and I'm by no means an electrician so I don't have the knowledge/skill or need for a highly technical highly redundant solution. This project is a prop; it's not small but it's not very big either so space is going to be a consideration. There are going to be 4 sets of LED's and only one set can be on at a time. Currently my plan is to use an Arduino board and some transistors along with a battery back from a RC car/helicopter/etc to power the LED's and insure that only one set is on at a time. Now for the questions:

What considerations are there as far as wiring the groups of LED's up in Series vs Parallel? Being a small scale hobby project does it really make a difference either way?

I read in another post on the site about a similar topic that it was recommended to use a current limiter. Is that something I should consider as well? As I said the power source will most likely be a battery pack from a hobby RC (LiPo or whatever they are currently making them out of). Are those consistent or will there be enough variation in the voltage/current that I need to find a way to mitigate the differences?

If you have any other things I really need to consider for this project please feel free to note them so I can do some research.

Please note when you respond that I'm not going to understand complex electrical diagrams or formulas. If the answer is pretty complex you might need to just point me in the direction of some reference material and let me research it. Also if you suggest using current limiters or any other specific pieces of equipment a link to any electrical website's part page for one of them would be appreciated. That will help me confirm I'm looking for the right thing when I get around to buying one.


texts: How to test transistor with Built-In Biasing Resistors

texts: On a GPS device pcb, I found a small smd component  that is marked as "22p V2". I found (tell me if I am wrong here) that it is a transistor like DDTA144WCA-7-F SOT-23-3 package, with built in biasing resistors R1 and R2 . So, If the last conclusion is correct, how to test this transistor with a DMM to check if it is ok ?


texts: Finding value of slip in an 3-phase delta connected induction motor

texts:
I know the equation for slip is

          s= (Ns-Nr/ns)x100

and that to find Ns is

         Ns= f/p.

I have been given running speed (16.2 rev/s), total number of poles (18), frequency (50Hz).

Can someone help explain how to get a value for Nr?


texts:
I am designing a PCB board for our vehicle tracking device. Here the device will track GPS location and send it to the user.
This is a battery operated device.
Our power station provides us 12v input voltage and by using this we want to charge our device and operate as well in the same time.
I am using here MP2617H (MP2617HGL-P) PMIC battery charger with power path management for single-cell Li-ion.
When I give 12V input to our circuit, I expect to get 4.2v at Vsys PIN and battery should be charged too at the same time but I get 0V at Vsys Pin and same as on battery connection point.
Here I am attaching a schematic and layout file of that.
Please help me into find out exact problem.


texts:
I was looking over some code that implemented a circuit using an "explicit enumerated state" VHDL implementation.

I am confused as to what this code snippet does, my confusion is syntax related so any help deciphering VHDL here would be great:

case state is
   when SO => state <= S1;
   when S1 => state <= S2;
   when S2 => state <= S0;
end case;


texts: Instrumentation Amplifier output mysteriously increases upon connecting across a resistor, compared to connecting the same voltage directly across it

texts:
I am designing a simple resistance measurement circuit. Resistance range is from \$10m\Omega\$ to \$10k\Omega\$ and desired accuracy is 0.1%.

The circuit provides constant current to the resistance using a transconductance amplifier. An instrumentation amplifier is used to measure the voltage drop across the resistor. The current through the unknown resistance has to be sinusoidal, as per the requirements of my assignment.

When I connect both the instrumentation amplifier inputs to ground, I get a voltage at the output of \$2.22mV\$:

I've found that this is due to the offset input voltage. To overcome this, I have included a voltage source on the inverting input (pins 1 and 5 - the offset null pins - are not enabled in the spice model). This minimizes the output voltage offset:

I tested the circuit using a sinusoidal signal of \$1\mu V\$ RMS (the lowest I'll be working with), and the output is perfect:

Now the problem:

When I connect the inputs across the unknown resistance, with the constant current source (transconductance amplifier) supplying current to that resistance, even though the voltage drop across it is still \$1\mu V\$ RMS, there is a mysterious increase in the output of the instrumentation amplifier:

As the simulation shows, this increase happens in final op-amp of the instrumentation amplifier. I'm completely confused by this. Why has the output increased all of a sudden, even though the voltage drop being measured is the same? How can I get the accurate output?


texts: Arduino Nano: Measuring tiny voltages with an analogue input

texts:
I need to measure 0v to 40mV as accurately as possible with the 10-bit ADC on an Arduino Nano. I only need approximately one sample per second.

I plan to hold the AREF pin at 40mV above ground, properly shield everything, use low-pass filters in hardware and software and use a properly smoothed power supply.

What sort of accuracy am I likely to get?
What else could I do to improve the accuracy?


texts: Good night everyone. I came across the term "slow drift" when reading a paper on an electronic design, and I am not quite sure what it means. The author said he used a low pass amplifier to remove slow-drift to the non-inverting input to an operational amplifier. What exactly is he saying?


texts: Maximum clock frequency of microprocessors

texts: Recently, I have heard that AMD has released the new Vishera series of FX processors which run at 5 GHZ. My question is whether there is any upper bound of clock rate of a processor? That is can we keep increaing the clock rate for ever? What electrical problems will we face at higher clock rates?


texts: LMR64010 wrong feedback voltage and wrong output voltage

texts:
The datasheet can be found here.
The typical application circuit is shown:

And my schematic:

The difference is SHDN pin is directly linked to input, since I never want it to be off.
The layout:

The issue is that with 3.7V I get 0.5V on the feedback pin, although the datasheet specifies 1.2V, and output voltage is 4.5V. Board heats up around that region as well. I have not found any shorts.
The PCB:

I have followed the design guide, and yet something is up, and I cannot seem to figure out what. If you have any suggestions regarding what else to check, please do tell


texts: The difference between Atmel ATmega16u2-MU and -MUR

texts:
What is the difference between ATMEGA16U2-MU and ATMEGA16U2-MUR?

Atmel lists these 2 codes in the table on their product page but I could not find any explanation in the datasheet.


texts: Is my amplifier circuit any good? Base voltage divider bias not the same as IRL

texts:
I have designed an amplifier circuit using my limited knowledge about transistors. Here is what I've got. The input is from a audio jack from my cellphone. The frequency response is at about 1kHz as you can see with the 160uF cap on the preamp. I want an output of about 20 - 30W so with 12V 2,5A.

I want all the parts so that I don't have to go twice to the store. Please give your feedback on this circuit. I have also played with small low output power BJT amplifiers "pre amps" like the BC327-40 or BC237 and I noticed something when I make a voltage divider to bias the transistor the measured bias voltage is less forward bias than intended or calculated. When I make a voltage divider without anything else on it the voltage reading is right.
Does anyone know what's going on?


texts:
In the last few days I spent working with NPN transistors and measuring their characteristics.
My aim was measure VBE and IE when transistor will turn on (transistor as switch).
For all tests VCE = 3.3V.
I started with S9013. I got data like these:
VBE=0.5V ; IE = 0.007mA
VBE=0.6V ; IE = 0.05mA
VBE=0.8V ; IE = 100mA

(there is a jump from 0.6V to 0.8V when transistor is turned on)
When I tried to measure the same for BC546B, I got:
VBE = 0.5V ; IE = 0.004mA
VBE = 0.6V ; IE = 0.17mA

around VBE=0.68V, the transistor turned off and VBE started to jump around from negative to positive values.
According to a datasheet VBE(SAT)=0.7V; VBE(ON)=0.55-0.7V.
Could someone explain me what happened? The transistor was new. I wouldn't expect that it's broken.
Update.  Answer for questions in the comments:
There isn't any resistor to limit current via led diode. I considered resistance of diode as limiting factor for current.
Transistor case wasn't hot. The current was too small during measuring.


texts: Choosing a relay, suppression diode and transistor for switching car power from a PIC pin

texts:
Here is my circuit that's hopefully going to be a custom timer circuit.
It has two inputs (ignition wire and headlamp wire), it has one output that will be used to switch a relay.

nb. "D31A*" is a Frizting part for a relay that's the closest I could find.

D1 is a suppression diode to protect the transistor from transient voltage
when the coil switches.
I'm somewhat confident it's wired the correct way, with the diode cathode
connecting to the positive side of the coil.

The PIC pin is wired in series to a 10K ohm 1/4 watt resistor to the base of
a transistor.

I have chosen BC547 for the transistor, because I have some spares,
and the circuit works on my breadboad.  I had tried with 2n4401's but the
Collector/Emitter continues to conduct after the Base is pulled low,
which I found a bit strange and could find no mention of in the datasheet.
Perhaps something else is causing it?

The relay I like at the moment is this one:
http://www.rapidonline.com/pdf/60-1910.pdf
This has spade/blade terminals on the bottom and suits my environment.

Relay Partnum: IMO SRZ-1AT DL 12VDC
Relay Datasheet: http://www.rapidonline.com/pdf/60-1910.pdf

The datasheet indicates the relay is avaialble with a diode built in, but
I've been unable to find one and think it may be special-order only.

The load the relay needs to switch is 12V @ 1.5A continuous, 3A peaks.  I'm using unregulated vehicle power into the positive side of the coil, is this okay?  I had considered solid state relays but they're really expensive! Might one be suitable for this or is a 1.5A continuous with 3A peak too much?

*The device I'm switching on and off with the relay can handle unregulated vehicle power already.

What suppression/rectifier diode should I use? How do I know?
Is a BC547 okay to go between PIC pin and relay coil -ve side?
Is 10k the right resistor value for the transistor? How do I know?
Is the relay I'm favouring a good choice for my simple switching example?

Update - New schematic following a telling-off from Olin :)


texts: Piezo Transducer - Constant weight increases sensitivity, why?

texts:
I currently have a piezoelectric transducer connected up to an Arduino in the following arrangement

The piezo is normally not very sensitive, unless I tap my finger directly on the sensor, or knock reasonably loud on the desk.

However when I apply a constant weight to it (using a pair pliers for example), it becomes surprisingly sensitive, where it can detect my footsteps.

Why is this?

I found a video demonstrating this phenomenon:
https://youtu.be/pDZ9H9sHOzI?t=25


texts: Can you use arduino for other avr chips?

texts:
Example:
Arduino leonardo uses Atmega32U4. What if one wants to program/develop for the plain ATmega32.


texts: NFC standards ISO 14443, ISO 15693 and ISO 18000-3. Which of them are most supported by smartphones?

texts:
I want to do this: mobile app <-> NFC <-> microcontroller, in order the MCU can communicate with Android or iOS apps via NFC hardware.

I have two options of low-cost NFC chips, these chips don't support the same standards. Supported standards are:

ISO 14443, using NFC chip M24SR04

or

ISO 15693 and ISO 18000-3, using NFC chip M24LR04E

Which of theses standards is most used in modern smartphones? Or both are supported on most mobiles? I want to make a choose regarding the NFC chip based on that information.

Actually I want to make it via NFC and I don't want any type of RFID, I want to communicate the MCU with the apps via NFC.

This is on Wikipedia:

ISO/IEC 14443 Identification cards -- Contactless integrated circuit cards -- Proximity cards is an international standard that defines proximity cards used for identification, and the transmission protocols for communicating with it.
ISO/IEC 15693, is an ISO standard for vicinity cards, i.e. cards which can be read from a greater distance as compared with proximity cards. Such cards can normally be read out by a reader without being powered themselves, as the reader will supply the necessary power to the card over the air (wireless).
ISO/IEC 18000-3 is an international standard for passive RFID item level identification and describes the parameters for air interface communications at 13.56 MHz.

Regards.


texts: Voltage surge during transition of high side mosfet in half bridge mosfet gate controller

texts:
I'm working on half bridge mosfet gate driver using IR2184 and IRF540N mosfets. You can find circuit diagram and scope captures in images.

I have observed that there is a small spike (LC tank like output) at the gate of low side gate driver output whenever high-side gate driver output switches.

I can not upload 3 images due to smaller reputation but you can find all 3 images here

Figure 1, shows circuit diagram of half bridge driver and all the values are calculated from infineon application note AN-978. All the grounds i.e. microcontroller, gate driver, half bridge are common.

Figure 2, shows scope capture of half bridge driver. I observe surge on gate of low side driver output. This surge in turn reflects at microcontroller PWM output.

I have observed microcontroller PWM output without connecting it to driver and that PWM output is clean.
From other posts like here I understand that length of power supply cable and all that forms a LC like circuit that causes this.

Then I implemented on breadboard and take utmost care that all the components have minimum distance between them as possible. After that amplitude of surge reduced to what you see in scope capture.

Then I connected RC snubber circuitry across D-S terminals of both the mosfets and RC of both the circuits is 100 kHz as maximum signal frequency in system is 32kHz PWM frequency. Scope capture of this has also reduced amplitude of surge further. But how to get rid of it completely?

Figure 3  shows scope capture after adding RC snubber to the system.


texts: When does a register need to get a load control-signal in order to be updated at the next clock?

texts:
I know this is a pretty basic question, but I didn't succeed to find an unambiguous answer.
Does a register need to get load signal in the cycle in which the new value computation is made? or at the beginning of the next cycle? Ill give an example to make my question clearer:

lets assume I want to increase PC (program counter register) value by 4 every cycle. In t0 the initial PC value is been transmitted to an adder, which calculate PC+k and is connected back to the PC's entrance. In order that in the next clock t0+Tclock the PC value will be updated to it's new values PC+k , does the controller should have sent a Load signal in t0 or it should sent a Load signal in t0+Tclock (the next clock)?


texts: Upgraded 10 turn potentiometers don't work whereas the original 1 turn potentiometers do. Why?

texts:
I bought this adjustable power supply kit and successfully assembled it. I wanted to upgrade the potentiometers to 10 turns so I could have fine control over the current and voltage limits set. Both potentiometers are 10K ohm and I have tested both to make sure they were in that range. For some reason, the output of the board drops somewhere like -0.5V when I try to use the upgraded potentiometers but works fine with the originals. What is causing this?

These are similar to the originals, only without the rear two pins (all i could find)

These are the upgraded potentiometers