texts: How to calculate how much current is available from Buck regulated Solar Panel

texts:
I'm trying to work out how much current my solar circuit could sustain under normal conditions.
I have an monocrystalline solar panel claiming 5W @ 12V (17.8V Vmp, 5Wp) based on their data sheet.
The data gathered by CEDA from MIDAS near to where I am suggests that the average (incl. night) for the whole year was 470KJ/m2 per hour or ~130.55W/m2 given \$P_{(W)} = \frac{1000\times470_{KJ}}{3600_{s}}\$
The data provided by MIDAS gives "solar irradiation amount" measured in "KJ/m2" in hourly increments for a given recording station.
Based on this information and the power curve in the data sheet, I would expect on average I would be able to draw around 150-200mA @ 12V.
The Buck/Boost module I use contains an LM2596 which advertises ~80% efficiency when the input is 12V with a 5V 3A load.
Does this mean I could expect ~80% of the current from the solar panel to be available at the output side of the Buck?
To this end, do I potentially have at least 120mA @ 5V given input of 150mA @ 12v available on average?


texts: Impedance match Fishman guitar pre-amp to IRIG2HD

texts:
I'm looking for some help in understanding impedance matching.  I'm hoping one or more of you technically savvy electronics folks will jump in and give me a simple circuit recommendation.

Specifically I want to try to build a passive "pad" that goes between the output of a Fishman Prefix Plus built-in guitar pre-amp and the input of an IRig HD2 guitar-audio-to-usb converter.  My issue is that, as it stands, I have to turn the volume control of the pre-amp as close as I can to it's minimum value (like 0.01, which is iffy), and set the gain of the Irig input hard to it's minimum value to get any kind of decent sound.  Anything else results in lots of distortion.  I'm trying to get a clean guitar sound.

https://www.fishman.com/products/series/prefix/prefix-plus-t-onboard-preamp/

https://www.ikmultimedia.com/products/irighd2/index.php?p=specs

I get the feeling that by using the extreme lowest setting on the pre-amp I am not in the sweet spot of the pre-amp design.  I feel like it makes the sound tinny ... I'm always lacking bass when I use the device (compared to just plugging my guitar into the Yamaha Stagepas PA).  It's just my noob idea that the amp was probably designed to be used in the middle, rather than at the extremes of its gain settings.

So, I'm thinking about making a passive "pad" that basically consists of two resistors.

input    O------- R2 --------+----------------O output
                             |
                             R1
                             |
ground  O------------------- +----------------O ground

My basic, very limited, understanding is that such a passive pad consists of a voltage divider created by resistors R1 and R2.   I really have no idea what values to use, although I sort of think their ratios should be about 9:1  where the value of R2 is about 9 times greater than the value of the "shunt" resistor "R1".   Rather than just guess, I thought I would ask the community.

The specs for the devices are copied from the user manuals  Here is what I see:

FISHMAN Guitar Pre-amp

Nominal Input Level: -20dBV
Input Impedances: 20MOhm
Output Impedance: "Less than 3.5kOhm"
Nominal Output Level: -12dbV

IRIG HD2 audio-to-usb converter

Maximum Level: from 307mvpp to 8.36Vpp
Gain Control Range: 28.7 dB
Input Impedance (guess): 380 kOhms

I cannot find the actual input impedance specification for the IRIG HD2.  There is a reference in the user manual that it is a "high-Z input".  I am guessing it is simllar to the input impedance for the IRIG2 which IS specified as  380kOhms.

So, given those specs, what should be the values of R1 and R2?

Any other thoughts on what I'm trying to do here?   I'd sure like to get a good sound and a feeling of control instead of a tinny sound and a pre-amp that is turned down to 0.01 ....


texts: Barrier voltage and temperature of a PN junction

texts: Why does the barrier voltage of a PN junction decrease by increasing temperature ? Please if possible , i want to understand the inner physics of what happens


texts:
how can i solve this problem.

Thank You.

Best Regards


texts: Low pass filter offset voltage question. LM358, INA129

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I am designing a low-pass anti aliasing filter.  I have set my cutoff frequency to be at 500Hz, and my sampling frequency at 1000Hz, but I'm not that far yet.

I designed a 4th order butterworth low-pass filter, but am having some issues at the output with some small offset.

Is this due to my op-amp's input offset voltage?

Here is my schematic.

I run a transient analysis and find there to be about 50mV of offset on my output.

Finally, here is a picture of the AC analysis frequency response.  It matches my criteria.

My question really is why am I getting this offset in my final signal and how can I get rid of it?  Do I need to compensate for component non-ideal values?

Thanks!


texts:
How does the Parallax Propeller stack up against other multi core solutions?  I just saw an article about the open stomp project that won their design contest.  I wanted to see what other people thought of the chip.  Any similar, but better products?

How does spin rate?


texts: Using arithmetic operations in systemverilog

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I was trying to create a module for using the sensors that I recently bought. My module works well in simulation , synthesis and implementation. but when I used my module inside the top leveled module, I saw that while synthesizing it, it creates some registers outside it's module. With trial and error I found out that the problem is from a sequence of arithmetic operations.

module Sensor_handle_dev1(
    input logic i_clk , i_reset , i_echo,
    output logic o_trg,
    output logic[7:0] o_distance , sensorNum
    );
    assign sensorNum = 8'b1;
    logic[1:0] IdleState , CatchEchoState , CountState , PackUpState;
    assign IdleState = 2'b00;
    assign CatchEchoState  = 2'b01;
    assign CountState  = 2'b10;
    assign PackUpState = 2'b11;

    logic next_trg;

    logic[1:0] curState , next_state;
    logic[31:0] l_count , next_count;
    logic[7:0] next_distance;
    always @( posedge i_clk )
        begin
            if ( i_reset == 1'b1 )
                begin
                    curState <= IdleState;
                    o_trg <= 0;
                    o_distance <= 0;
                    l_count <= 0;
                end
            else
                begin
                    curState <= next_state;
                    l_count <= next_count;
                    o_distance <= next_distance;
                    o_trg <= next_trg;
                end
        end
     always_comb
            begin
                    next_trg = o_trg; // <-- default value is flopped value
                    next_distance = o_distance; // <-- default value is flopped value
                    next_count = l_count;
                       case(curState)
                             IdleState:
                                begin
                                        next_count = 0;
                                        next_trg = 1;
                                        next_count = 0;
                                        next_distance = 0;
                                        //# trig wait
                                        next_state = CatchEchoState;
                                end
                           CatchEchoState:
                                begin
                                        next_trg = 0;
                                        if ( i_echo == 1 )
                                        begin
                                            if( l_count < 32'b101101110001101100000000 )
                                                begin
                                                    next_count = l_count + 1;
                                                    next_state = CatchEchoState;
                                                end
                                            else
                                                begin
                                                    next_state = IdleState;
                                                end
                                        end
                                        else
                                            begin
                                                next_state = CountState;
                                            end
                                end
                           CountState:
                                begin
                                     // here is the problem
                                    //next_distance =  ((l_count * 68) / 100000) + 1;
                                     next_state = IdleState;
                                end
                           default:
                                next_state = IdleState;
                           endcase

            end

endmodule

and the schematic looks like this

how can I implement to evade this situation ?


texts: Light dimmer circuit, need some help with connections

texts:
So bascially, the bottom optocoupler (U5) is the zero cross detector which will send a pulse to pin 3 when a zero is detected and fire an interrupt. This interrupt will trigger a timer which will fire the second optocoupler(U7) when the timer has elapsed (Brightness level will determine the time delay)

Now for my question, I want to know if I connected everything fine, especially the triac part, I am unsure about that


texts: How power is conserved in tapped capacitor impedance matching circuit..?

texts:
I have recently came across a text of impedance transformation provided by a tapped capacitor arrangement.
Its a rare and unique text explaining the working of tapped capacitor network in terms of conservation of power.
figure 6.31a) is an untapped case when no tapped capacitor is used..fig 6.31b) uses a tapped capacitor network(C1&C2)

The law of power conservation states that..If the magnitude of the power of an individual component in a circuit increases to a certain amount then there should be some compensatory change by the same amount in power of another component to maintain the overall power of the circuit constant.

In case I IL and Vi is constant, in second figure with use of tapped cap. Vi and IL changes which decreases the output current Io and increases the output voltage Vo, hence the latter can be thought of as increase in impedance.

Case 1 Vi and IL constant and power is conserved, whereas in case 2 Vi changes , IL changes which results in increase in Vo and Io,

My query is:-what kind of compensatory change is produced or observed when Vo and Io changes with the use of tapped capacitors, hence increasing the load impedance???

Thanks!!


texts:
We are working on a project. Our goal is to measure the DC current of a cable ranging to 1A-50A. However the hall meter doesn't seem to react at all when putting a cable with 2A close to it. We get a voltage difference with a strong Magnet.

How do we go on from here? How do we amplify the signal enough for us to notice it? Do we need an instrumental amplifier?

We are using Arduino UNO.


texts: Any reason why the MIC920 op amp should not be used in SINGLE SUPPLY mode?

texts:
I understand that practically any op amp can be used in single-supply mode as long as the application (interface, measurement, etc) does not require dual-supply for specific reasons.

Is there a reasons why the MIC920 (being a general purpose op amp) does not list single-supply (i.e. 0-5 V) as an option?

Is there a way to determine if it's rail-to-rail?

The planned use would be amplification of mV level positive-only pulse signals by 100-1000 times between 500 Hz - 20 kHz for reading by an MCU.


texts:
I have a two layer board. Analog signals on the top layer and power traces on the bottom layer. Should they cross each other at 90 degrees? How bad would it be when the bottom trace and the top trace "lay on top each of other"?
My analog signal has a bandwidth of around 1MHz


texts: how to calculate the output value of an lm335 sensor

texts:
i am having a problem in calculating the output value from the lm335 precision temperature sensor where its output value is the input of ADC0804.
With increase in temperature the value decreases instead of increasing.What might be the problem?


texts: how to demux 100V to 300V DC signal into 8 channels?

texts:
I need to 8 channels of 100Vdc to 300vdc, load current 10mA to 80mA.

my idea is to use a step transformer to step up dc 5v 1A source to 300Vdc 50mA (typical application).

low voltage side of the transformer (5v side) will be controller with MOSFET using a microcontroller and the output side or high voltage side will connect to load.

I need 8 channel outputs with a single transformer setup.

how to demux 300Vdc channel into 8 channels? I am using a single channel at a moment

output will be used to sense muscles nerves

also, I want to know is it possible to use a boost converter to sense muscle like LT8331 9V to 16V Input, 135V Boost Converter


texts:
I'd like to properly power a gadget off USB (2.4A USB powerbank https://www.amazon.com/Anker-20100mAh-Portable-Charger-PowerCore/dp/B00X5RV14Y/ref=sr_1_3?ie=UTF8&qid=1512261941&sr=8-3) consisting of:

A cheap power only USB Y-splitter
Raspberry Pi Zero
A boost converter from 5V USB to 12V
4 LEDs in series
An ULN2003A used to control a unipolar stepper motor
Some sort of graphical output (OLED/Character LCD)

Adding all the respective current values together, the max. current draw of my gadget should be:
180mA RPi Zero  +  500mA LEDs (384mA for perfect transformation, I assumed 75% efficiency)  +  165mA Stepper Motor  +  165mA Character LCD = 1010mA total power draw.
What I know so far:
Having delved into (and having been overwhelmed by) the USB specification, I have found that USB can under some circumstances supply 5V@1.5A (or even more).
Back in the day, there apparently used to be a kind-of handshake process (enumeration/negotiation/...) which was necessary to allow >100mA. I found an article explaining some aspects of USB charging: http://www.electronicdesign.com/interconnects/introduction-usb-power-delivery

It’s important to note that BC-1.1 was released as an Engineering
Change Notice (ECN) to USB 2.0 and it significantly deviated from the
sanctions of USB 2.0. As per USB 2.0, any USB device could be
classified as either low power (5 V @ 100 mA) or high power (5 V @ 500
mA). On connection, a USB device was allowed to draw 100-mA current
initially while enumerating and negotiating its power budget with the
host. Based on the enumeration, the host would either raise the power
delivery to 2.5 W or continue at 0.5 W.
The battery-charging spec went on to define more power sources than
what was recommended above:

Standard downstream port (SDP): power source compliant with USB 2.0 Spec.

Charging downstream port (CDP): power source not compliant to USB 2.0. CDP can supply up to 7.5 W (5 V, 1.5 A) and the 1.5-A current can be supplied before enumeration.
...

Dedicated charging port (DCP): There’s no enumeration here, and charging
occurs without any digital connection. DCP supplies up to 1.5 A and 5 V.

There has been a similar question before ("Dumb" power from USB), but it does not mention SDP and CDP. Apparently, you can achieve CDP-mode when you short the data lines together.
My question:

Can I get the full 5V 1.5A (or even 1.8A) power from an ideal (100% USB standard-conforming, protocol-following) port without any fancy enumeration/registration/...
Can I get the full 5V 1.5A (or even 1.8A) power from a real world (a decently beefy power bank like the Anker in the Amazon link) port without any fancy enumeration/registration/...
In case I need negotiation, couldn't the Pi just handle it in the name of both sides of the Y-splitter (they terminate in one Micro-USB port, so the power bank shouldn't even know that the cable splits somewhere downstream...

Here's how I intend to wire it up:


texts: Heatsinking considerations for Common Cathode Rectifying Diode

texts:
I am using this as rectifying diode in full bridge configuration in one of my power supply designs. My questions are regarding heatsinking of the diodes. They are as follows:

Do I need to use insulation to isolate the diode's thermal tab and the heatsink from each other? If yes, should I connect the heatsink to Ground?
If insulation is not used, should the heatsink be connected to the rectifying diode's thermal tab terminal (cathode) through the PCB, through the heatsink's mounting screws?

The design specs are:

Input Voltage: 90V to 240V AC

Output Voltage: 55V DC

Output current: 7A.

[Edit]

The power supply has PFC+LLC configuration. The part specified above is used to rectify the output of the LLC stage in bridge rectifier configuration as shown below:

Thanks in advance.


texts:
I currently have a design that features a BLE SOC that interfaces to a PCB antenna. Both the SOC and antenna are placed on one side of the PCB. What I'd like to do is place another (different) BLE SOC on the other side of the PCB and either:

Use the same antenna for both SOCs.
Put another PCB antenna on the other side of the board, overlapping the first antenna.

I understand that if I try to use the same antenna for both SOCs, that matching it will be difficult because I'll have to use via to connect the tracks.

I think the preferred approach would be option 2, but I'm unsure whether having two overlapping antennas in the same board space (albeit on opposite sides of the board) will be a good idea from an RF perspective. Can anyone offer any advice?

I'm not intending to use them at the same time, I'm going to populate one of the SOCs, not both. I want to do this because I'm trying to migrate to the second SOC, but do not want to do it in one PCB spin.


texts:
The manufacturer of the brushless motor does not specify a lifetime for the particular motor I am using (BLDC5-R-57BL120L2.) For my application it is essential that the axial and radial movement of the shaft as result of bearing wear remain within tolerances.
I was thinking of putting two screws very close to the shaft, so when the bearings wear out too much, the shaft comes in contact with both screws, completing a circuit. What I do not like about this approach is that it does not give me an early warning when the motor is about to fail. It only works for radial movement of the shaft, not for axial movement. It also ruins the motor shaft and the screw contact.
How would I detect the radial and axial movement of a motor shaft as a result of bearing wear of a brushless DC motor?


texts:
I am trying to quantify the noise of the accelerometer inside the Parrot AR Drone 2.0, but the signal contains odd spikes. I simply placed the drone on a table and recorded the acceleration for about 30 seconds, without turning the rotors on. The measurements then produce the following image:

Without mean subtraction:

There seems to be a fairly horizontal line, that contains very large spikes (up to +-0.1 m/s^2). This holds for all axes of the accelerometer. I expect some kind of normal distribution, but something odd is going on. Does anyone have any ideas? Simply removing the noise using filters is not what i'm looking for...


texts:
I have this output signal (attached) where I am trying to work out:

The instantaneous Power
The average power

However, I am a little bit stuck and don't quite understand how to go about doing this. Could someone point me in the direction of the calculation and how to solve the equations if possible (maths isn't my strong point). The exact answer is not necessary; a ball park figure and the method used to calculate will be more than useful. If I wanted a piece of equipment to calculate the Voltage RMS and Current RMS what would be a good choice?

Channel 1 is the yellow signal and is the voltage. They are 10V increments and max voltage can be taken to be 40V.

Channel 2 is taken by a current clamp and is set to 100mV = 1Amp. Max current can be taken to have a reading of 1.4V (14Amps?). They are 1V increments.

The signal repeats every 4ms. (250Hz)

The time scale is 50us.

The voltage is taken across a 1 ohm resistor and the current clamp is placed before the 1 ohm resistor.

Thanks.


texts:
The last time I did a successful PCB, the drill hole size relative to the component pad size is rather huge to the point where when I entered the soldering stage, the component wires were not connecting to the pads correctly.

What I want to do in eagle is change the drill holes on every device (with small pins) on my PCB so that they are about 1/64ths of an inch instead of Eagle's preferred size, that way, when I drill, I drill a small amount of copper but at the same time, the copper will meet with the hole and the odds of a strong connection are higher.

Is there a quick way I can make the drill holes smaller in eagle without having to manually edit each part one-by-one?


texts: Unconventional voltage regulation scheme in the secondary of an ATX power supply, how does it work?

texts:
The regulation scheme for the +3.3 V output in this ATX power supply schematic caught my eye as strange. I just saw the schematic online, I do not actually have the physical unit.

Close-up on the portion of interest, with irrelevant circuitry removed:

My understanding is as follows:

The taps 9 and 11 of the main transformer T1 output ~5 V AC (out of phase to each other) relative to the grounded center tap SC. This AC output is rectified directly for the +5 V and -5V outputs. The same taps are in series with the inductors L5 and L6, whose reactance at the operating frequency has been chosen so that they drop approximately 1.5 V, and the remaining AC is rectified into 3.3 V DC by the D23 common cathode schottky diode pair.
L1, C26, L8 and C28 form a low pass filter for reducing the voltage ripple and noise to an acceptable level. R33 dissipates 1 W at all times, presumably because the regulation at low load currents would not otherwise be satisfactory.
A voltage sensing wire that goes all the way to the motherboard main power connector is soldered to the +S pad. Its purpose is to sense the actual output voltage at the motherboard, in order to cancel out any resistive voltage losses caused by high currents in the wiring.
The TL431 shunt regulator attempts to keep a 2.5 V potential across the R and A pins by drawing current from C. The resistors R26 and R27 form a voltage divider which causes the R pin to reach 2.5 V when the output voltage reaches 3.34 V, after which the TL431 starts to pull current from the base of Q8, a PNP BJT, turning it on. C22 and R28 are there to prevent overvoltage at power-on. R25 allows sufficient regulation when the sensing wire is disconnected.
Charge from the 3.3 V output capacitors can flow trough Q8, R30 and either D31 or D30 to the inductor (L5 or L6) currently undergoing the negative portion of its half cycle:
Right after the positive to negative transition, the inductor current ramps down to zero. Depending on how much Q8 conducts, current will then start to flow backwards into the transformer trough the inductor, charging its magnetic field in reverse. When the voltage then transitions back to positive, this established magnetic field must first be overcome before any current can start to flow back to the 3.3 V output. This delay reduces the energy transmitted per cycle, lowering the voltage.

I am aware of the saturable core reactor and I suspect that something similar is in play here, but I currently cannot wrap my head around this. There is no separate control winding, and according to the schematic L5 and L6 are entirely separate, not sharing the same core.

How is feeding current backwards trough L5 and L6 more efficient than simply shunting the excess current to ground; I do not understand how the energy spent into building that reverse inductor current is then recovered. What purpose does R30 serve in the circuit? What benefits and drawbacks does this scheme have? Why isn't this used more often?


texts:
Can anyone tell me why we use a voltage divider circuit with an LDR for an LDR robot?

For example, why can't we directly take the LDR output and feed it to the ADC port in an ATmega controller? Why must we use this order?

Light --> LDR --> voltage divider circuit --> ADC pin

I read somewhere that it was used for "buffing" but I couldn't really understand what it meant.


texts: Calculating resistor's temperature at equilibrium

texts:
I'm trying to characterise a resistor's temperature at equilibrium when I know the voltage on it and the ambient temperature. I have a few ways to measure but I get mixed results, so I'm searching for a theory to compare to. I'm a second year physics and EE student and I haven't done thermodynamics yet, so I'm kind of lost.

I can use curve fitting to find hard-to-reach constants like its heat capacity. I can also control the ambient temperature and the power supplied to it. In the measurements it seems like the temperature is rising exponentially (with a negative time factor).

Is there an equation or some models I can dive to?

Thanks in advance.


texts: How to code communication between two enc28j60?

texts:
I am new to embedded programming and enc28j60. I am developing a project which includes two boards with Enc28j60. The working of the system is explained below.

board 1 :  It will request data from board2 over enc28j60.
board 2 : It will sample a sensor data at the rate of 10khz upto 4500 samples. sample number can vary. This board have to transfer this sampled values to board 1 over enc28j60.

board 1 : atmega328p interfaced with Enc28j60.
board 2 : atmega328p interfaced with Enc28j60 and a sensor.

In the board2, the sensor part is already written.

Now my problem is the communication between two enc28j60. By reading the datasheet, i have done some code. As a initial steps i coded initialisation of MAC and PHY registers. Also written code for transmitting ethernet packet.

But I confused while searching about Enc28j60 communication on google. In almost all forums show enc28j60 is used for udp and tcp communication.  From the datasheet i didn't find such type of communication. Datasheet only speaks about MAC and PHY communication.

For my application, whether udp or tcp is needed? How to complete my application?


texts:
I have a nicely-spec'd wireless router that doesn't work any more.  (Sorry, I don't have a schematic, but it's an Asus RT-N16.)  I popped it open and found that it has one capacitor with a bulging top.  It's labeled 16V 680uf, but I don't have a capacitor with those exact specs.  But as long as I find another capacitor with roughly the same capacitance, I should be able to substitute that, right?

Q=CV
Q=16v*680uf
Q=10880C

I have a ton of random junk that has various capacitors with other specs.  For example, one is labeled 35v 470uf.

So, suppose I want to substitute this 35v capacitor.

C=Q/V
C=10880C/35v
C=311uf

Since the proposed substitute capacitor's 470uf > 311uf, is it likely that this substitution will work, or is it the case that I'm oversimplifying this and need to find something with closer specs printed on the side?


texts: Why rectangular waveguides are more popular in RF/Microwave compare to circular waveguides?

texts: I have seen in telecommunication, normally rectangular waveguide is used as the transmission line, what is the reason behind this? Why not circular waveguide is used?


texts:
I have a system transmitting UART (38400) over IR with a carrier frequency of 425khz.

How do I take a receiver led and feed this into a microcontroller. Obviously I can't just put it through an op amp and connect to the UART RX on the microcontroller because I need to remove/demodulate from the carrier frequency first.

What techniques can I use to do this?


texts: What is the simplest logic circuit + latch that satisfies this truth table?

texts:
This is not a homework problem, I'm just revisiting/relearning the practical applications of latches and logic circuits and I've been trying to figure this out on my own.
Basically, I want to turn one input bit into three possible states of two output bits. When the input bit is "0", both output bits should also be "0". When the input bit is "1", one of the output bits should be "1" and the other should be "0". Which output bit is "1" should alternate every time the input bit is "1". I suspect this can be done with two SR latches and an inverter but I can't for the life of me figure out how... any ideas are welcome!


texts:
I would like to know what are the available ICs for 16 segments display to control.

I have 1 digit three 16 segment display so I want to control those three displays separately by microcontroller.

It is not practical to connect all pins to microcontroller. Please give me any suggestions for that.


texts: How to place through solder pads of different shapes in EAGLE?

texts:
I searched everywhere and watched many eagle tutorials, but I couldn't find out how to place circle and square through hole solder pads.

In the Eagle parts list, I only found the octagon solder pad. I would really like to know how to place pads of different shapes, square, circle...

I've started learning Eagle yesterday, and I have managed to put together a 3PDT daughter board schematic and design a PCB:

Any help is very appreciated :)


texts: How to use an oscilloscope with a function generator?

texts:
I am taking a digital electronics class and I am utterly confused. I am using Multisim to design circuits, and for one of my labs I had to use a function generator with a oscilloscope. Here is a picture of my circuit.

As you can see, the negative wire is connected to Resistor 2 and Resistor 1. To me it looks like the circuit goes back into the function generator in the middle, but not in the positive terminal. Why is that? I thought the electricity had to flow from negative to positive? Also, it looks like the positive terminal of Channel A on the oscillator is connected to the negative wire coming out of the function generator. I don't understand this at all. Can someone please tell me how this works?

I am suppose to set the function generator to 5V. I think I did that by clicking on it and setting the amplitude to 5.


texts: Humming and voltage drop on p channel Mosfet

texts:
I am designing a high side switch using P-Mosfet to drive a heat element.
The Mosfet is driven by PWM from MCU, which in the test is around 40Hz, 10% duty.

Here is the schematic I am testing. I am driving the AOD403 with a N-channle mosfet. The heat element is supplied with 24V.

I am facing 2 issues here, one is that there is a unexpected amount of voltage drop between Source and Drain of the P mosfet, when the Mosfet is turned on. From the scope shot, we can see the voltage drop is around 3V. Where is the voltage drop coming from? The Rdson of the is pretty small, around 7mOhm or less. The current is maximal 6A, should the voltage drop just be maximal 28mV, right?

Yellow is the PWM from MCU;
Blue is the voltage across the heat element;
purple is scoped at the Gate of AOD403.

The other issue I am facing is that when switching the heating element using PWM, the circuit is runing with audio humming. Is there some way to over coming this?
Here is the scope shot with the rising edge.

Any hint is appreciated.
Thanks


texts:
I am new to electronics, and a professional programmer. I want to develop a sports IoT App and for this app, I need to detect how far a ball hits the ground from the sensor. There can be other stationary or moving obstacles (like a human, a bat etc) that the sensor needs to ignore and just detect and capture a moving ball's impact coordinates on the pitch (ground).

It's kinda baseball ball which means we can't insert or attach anything to it.

How can I do this?


texts: MC1314 voltage controlled attenuator circuit not working on breadboard - what did I do wrong?

texts:
I have an old quadraphonic system with a problem that I've traced to what I think is an MC1314.  (That's not the question.)  So I ordered a replacement, popped in and it didn't solve the problem.  I decided to make a test circuit based on the data sheet (available here https://datasheetspdf.com/pdf-file/570328/Motorola/MC1314P/1 on page 4 with notes on page 11.)  Here's the circuit I bread boarded:

The +18V was two 9V batteries in series.  Anyway, I plugged it in and blew the IC.  That leads me to suspect that 1) I screwed something up, or 2) The chip was bad, or 3) The chip actually wasn't an MC1314 or 4) The chip was an MC1314, but Motorola has recycled the number.  I haven't found any evidence of #4, seeing as how I ordered it from eBat #2 or #3 are also possible, and since I'm human, #1 is always a leading possibility.  Edit: What could have gone wrong?


texts: Equivalent Circuit of identical transformers connected in parallel or series

texts:
I'm trying to figure out how to solve the equivalent circuit for 2 identical transformers connected in series or parallel on the primary and secondary. Mainly I want to know what the equivalent leakage and magnetizing inductance will be for each different type of connection (Pri in parallel/sec in parallel, pri in parallel/sec in series, pri in series/sec in parallel and pri in series/sec in series). I know you can create a T model for the transformer but how does this model change depending on the primary and secondary connection. I understand how the equivalent turns ratio will change but I don't know how to simplify the model to represent it as one concise T model. This is similar to a matrix transformer but in this case there are discrete transformers with separate cores not one core and multiple windings on the core.

This is what I meant. Using this to create the T model.


texts: Why is CMRR effect multiplied by gain in this non inverting op amp configuration?

texts:
In this document Vout of a non inverting op amp is given as follows:

But why \$\frac{V_{in}}{CMRR} \$ is also multiplied by the gain?

I would write it as:

\$ V_{out} = \big[1 + \frac{R2}{R1} \big] \big[V_{in} \big] + \big[\frac{V_{in}}{CMRR} \big] \$

Common mode input voltage should produce an output of \$\frac{V_{in}}{CMRR} \$ by definition but yet in the document it is multiplied by the gain.


texts: Master switch placement for Li-ion charging circuit MCP73871

texts:
I am designing my first Li-ion charging circuit, based on the Adafruit Powerboost 1000C, and this is what I have so far:

I am probably going to also add a way to read the battery voltage based on this post, but that's not what this question concerns.
The circuit uses the MCP73871 to manage charging and load sharing, the BD4933G 3.3V voltage supervisor to turn off the load when the battery voltage is <3.3V, and the TPS61090 boost converter to boost the battery voltage to 5V (5.2 to allow fluctuations and drop), and also provide a status output when the battery drops below <3.45V.

I am wanting to know where the best place to put a master switch would be - would it simply be connected directly in series with the battery? Does it matter if its the +ve or -ve battery terminal? Is there a better place to put it?

Thanks in advance for your help


texts: Altium: problems with generation 3D body with IPC component wizard

texts:
I'm a big fan of this feature embedded in Altium. However some of the component generators have flaws:

Chip resistor and chip capacitor generators making me a wrong component height (despite the "minimum height" setting the resistor appearing too high, and the capacitor is too low)
SOD123FL body have no cathode designator

I think that there should be an editable file which I could edit to correct these errors or a setting section. But I did not find any.


texts: How can I deal with crossing wires when designing a PCB?

texts:
I'm finally dipping my toes into PCB design as I got around to finishing up my schematic for an upcoming project that I'm working on.
If it helps in finding a solution to my problem, this PCB will take a mixed signal approach. If not, please ignore it.
The issue at hand is essentially: how can I deal with rat lines that are crossed over each other? The only solutions I see is jump the trace from the top layer to the bottom layer, or redo the footprint from the IC.
It doesn't matter how many times I rotate or organize other components. The ratlines are always crossed over on each other.
I'm currently using EasyEDA as the schematic and PCB editor using the community's footprint design, so I am not sure if that's where I went wrong.
Be warned. This is my first time attempting a PCB design, so what can I do to improve?
Here's a picture with what I'm dealing with.

This is not the final product as I'm stuck on the left side of the board where the microcontroller is.


texts:
Disclaimer: Super newbie and first time poster here.

The MCP1700 LDO regulator datasheet states on p3 that the Droptout voltage is 350mV for Vout > 2.5V @ I=250mA. I thought great I can power my ESP32 from an 18650 battery. 3.7V - .35V = 3.35V. Works out perfectly! Well it doesn't. The regulator's Vout kept dipping below 2.5V and the ESP32 kept browning out.

I couldn't understand this until I went back and read the datasheet, carefully this time, and saw this note 5: Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its measured value with a VR+ 1V differential applied.

My question: If I need a whole extra 1V for the regulator to properly work, then why tell me that the drop out is 350mV? What's the significance of this information? I came across the same thing with multiple regulators so I must be missing something.

Thanks!


texts: Why does this buck converter output such low current?

texts:
I'm making my first attempt at building a buck converter, as a constant-current supply for a 700ma LED, from a 5V or 12V supply.  I have it working with the parts I had on hand, at about 88% efficiency, but even at 100% duty cycle, the output current is only around 70ma for a 5V input.  For a 12V input, it'll go up to about 185ma, but my diode starts to heat up then.  The switch is being driven at 62.5KHz directly from the PWM pin of an Arduino.  There is no feedback currently, since it's designed to power a specific load at a specific input voltage.

I simulated the converter in LTSpice before building it, though the parts aren't the exact same part numbers as in LTSpice, so I'm sure many of the important values are somewhat different.

On the breadboard, I used:

a DMG3420U (logic-level N-channel MOSFET)
polarized caps
1N4001 diode
a 47uh inductor I had around (I know nothing else about it's specifications, is there some way to measure the important ones?)

There are a few things puzzling me:

My understanding was that when the duty cycle is 100%, the diode would be reverse biased, so there shouldn't be any power dissipation there.  Why would mine be heating up?
Why is the converter only supplying 70ma?  What can I do to find out what is limiting it?

The LTSpice simulation shows it supplying around 850ma with a 99% duty cycle, but with different parts.

My circuit, with a 30% duty cycle.  Channel 1 is the gate pin of the MOSFET, channel 2 is the output to the LED.  The ripple is fairly low, so I think that means it's running in continuous mode.

My circuit again, with a 100% duty cycle.  At this point my bench supply says it's supplying 70ma, at 5.0V.  If I turn up the voltage to 12V, I get around 185ma out of it.

The FET is an N-channel FET I happened to have around.  Both capacitors are 10uf.  The diode is a 1N4001 (not ideal, I know.)  The inductor is a 47uh inductor I happened to have around.  I don't know anything else about it.


texts: Help me understand this high voltage amplifier circuit for driving a piezo actuator

texts:
I am researching HV driver amplifiers for controlling piezoactuators. My background is in physics, so I am a bit out of my comfort zone here. I came across the following schematic and have been struggling to understand it.

So with a bird's eye view I see an inverting opamp whose output goes to common collector (Q5) which then feeds to a common emitter (Q6), which acts as a shunt for current mirror (Q3/Q4), which supplies the push-pull output stage (Q1/Q2). Lets say Vcc=250 such that R3 sets the current mirror current to 500uA.

Assuming abs(Vin) is 5V, we have 5ma over R8 to virtual ground at pin 2 of IC1. This means that the circuit must supply a matching and opposite 5ma through R9 to maintain the virtual ground. Continuing to work backwards, this means that push/pull pair has to source or sink 5ma (plus whatever the load requires!) to make opamp IC1 happy.

This is the point where I start to lose my confidence. Based on the way Q5 is hooked up to IC1, I think it makes sense to think only of the current being sunk by pin 6 of IC1 (since it is attached to the base of an PNP Q5 it won't ever source current). From here the collector current of Q5 is shared over R6 and R7 (can solve using KVL so the drop over R7 and R6+diode drop are equal). The source page states "You can adjust R7 to minimize output dc offset voltage and slew rate", but I don't really understand how it achieves this? The lower R7 is, the more current Q5 has to supply (and IC1 has to sink) to get the desired end output. Does this mean R7 is setting the input impedence of the following stage?

To understand Q6's role I start with the case where Vin=0. Opamp IC1 will do whatever it needs to so that the collector current is the 500uA specified by the current mirror. When this is the case, the node between R4 and R5 is at "ground potential" and thus the output is at "ground potential". If Vin goes positive, IC1 will cause Q6 to turn more off, forcing current through Q1. The current through Q1 reduces Vce of Q1, driving the input more positive. The opposite of all of this happens with Q2 when the input goes negative. However, I don't understand quantitatively how the current through Q1 or Q2 translates to Vout.

D1/D2 serve to stabilize IC1 by limiting the excursion of IC1 pin 6 from ground. I get why these diodes have a stabilizing effect, but I do not understand why it is necessary in this case.

Okay so that is about as much as I have understood about this circuit. Any insights from you professional EEs out there would be greatly appreciated, especially resources where I might be able to learn more about circuits specifically like this.

Edit to add: Thank you Andy Aka for bringing it to my attention that I forgot to include the Falstad circuit simulation that I set up. It did help me to understand more of the circuit but some things still eluded me, hence the post.


texts: Unexpected values from insertion loss calculation in IEEE P802.3cg documentation

texts:
I'm looking at the insertion loss calculations from an IEEE document on P802.3cg (10SPE Ethernet). On pages 6 and 7 they talk about insertion losses over the cabling in a multi-drop scenario.

I'm following the calculation given here:

First they define cable insertion loss over 100m as:

$$il_{cable} = 1.23\sqrt{f} + 0.01f + \frac{0.2}{\sqrt{f}}$$

They don't specifically say what this value is measured in, but I'm interpreting this as dB from the context.

Next they define connection insertion loss:

$$il_c \geq 0.05 \\
il_c = 0.02  \sqrt{f}$$

This makes some sense. They're budgeting a minimum value of 0.05dB per insertion, and at the bottom of the page they state that values are valid for frequencies between 1MHz and 30MHz. Assuming that f is supposed to be in MHz, then:

$$il_{c(\text{1MHz})} = 0.02 \sqrt{1} = 0.02 \space (0.05) \text{ dB}$$
$$il_{c(\text{4MHz})} = 0.02 \sqrt{4} = 0.04 \space (0.05) \text{ dB}$$
$$il_{c(\text{16MHz})} = 0.02 \sqrt{16} = 0.08 \text{ dB}$$
$$il_{c(\text{30MHz})} = 0.02 \sqrt{30} = 0.11 \text{ dB}$$

These values are within an order of magnitude of the minimum bound they set above, so it seems reasonable that they're expecting f to be given in MHz. It also tallies with what they say on page 6, where they talk about 6 connectors resulting in a 0.3dB drop (6 x 0.05dB) at 4MHz, and 16 connectors resulting in a 0.6dB drop (12x 0.05dB) at 4MHz.

Finally they join these together for the case of a 1000m cabling run with 12 connectors, i.e. 10x 100m with 10 inline connectors and one connector at each end:

$$il_{link} = 10  il_{cable} + 12 il_c$$

$$il_{link} = 10 (1.23 \sqrt{f} + 0.01 f + \frac{0.2}{\sqrt{f}}) + 12 (0.02 \sqrt{f})$$

This all seems perfectly reasonable until I put numbers through it: at 4MHz this results in a fairly huge 26.48dB loss, and at 30MHz it's a whopping 72.05dB loss! I'm confused as to what's going on here. Have I made a mistake here? Am I missing something? I can't really get my head around how this system could reasonably operate at 4MHz when the signal is damped to just 4% of its original level by the time it reaches the far end of the cable, let alone at 30MHz when the damping takes it down to 0.025%.


texts: Why would large portions of traces be completely covered in solder

texts:
I've recently found, in some old stuff, a circuit board from an toy, specifically a target for a light gun (if you light up the photoresistor in the middle of the target with the light from the "gun", it generates a sequence of pretty lights).

What baffled me is that the traces look like this:

As you can see, a large portion of the traces is covered in solder. Since I wasn't able to deduce a sensible reason (only several nonsensible ones relating to either incompetence or improvisation), my question is:

What would be the rationale for covering the traces with solder in the manner shown?

For reference, here's the other side of the board:


texts:
I have a few questions regarding reduction of capacitive loading of oscilloscopes probes and cables in case of 10:1 probes compared to 1:1 probes. I am basing my research on these links:

Wikipedia: Oscilloscope - Basic types of sweep (addresses probes)
Wikipedia: Test probe (addresses passive probes)
Zone.ni.com: Probes

In the first link, it reads -

  a one meter direct (1X) coaxial probe will load a circuit with a capacitance of about 110 pF and a resistance of 1 MΩ.

Since the oscilloscope has 1MΩ||\$C_{inp}\$ (range up to 20pF), and coaxial cable will add 90pF/m, this will add capacitive load and reduce the bandwidth of measured signals.

Attenuator probes (10:1) will have 9MΩ||C (tunable) with the same circuit (again, probe capacitance is added in parallel and OSc input [1MΩ|20pF]). This attenuates the signal but increases the probe bandwidth to observe the high speed signals, if
$$Rp \times Cp = R_{osc} \times (C_{osc} + C_{lumped\,cable\,capacitance} ) $$

I didn't understand how the attenuator probe will present more bandwidth because 10:1 probe will also have the same cable capacitance (90pF/m), which is not reduced.
How will this balancing increase the probe bandwidth and reduce loading on measured signal?

I've not been able to simulate and see the actual effect on measured signal spectrum.
I have calculated that the impedances in parallel branches Z1 = R1||C1, Z2 = R2||C2||C3, and Z2/(Z1+Z3) should be 0.1.

I used Micro-CAP10 evaluation copy to simulate it, but I am getting weird results if I plot this quantity (Z2/Z1+Z2). I don't know what results CircuitLab would give.

Below is the equivalent schematic I used in Micro-CAP10.

simulate this circuit – Schematic created using CircuitLab

Edit:
The equivalent circuit is like 10MΩ shunted with ~14pF. So, the equivalent load on measured signal is reduced to 14pF. But it's not clear to me how one arrives to this equivalent circuit. Is there anyway to find the equivalent circuit of a more complex RC?


texts: Charge Measurement for Piezoelectric Sensor

texts:
I want to measure the charge displaced by a force acting on a piezoelectric sensor. The problem is I don't know the sensor so I have no idea how big the current generated by the sensor may be nor what the sensor parameters are (leakage Resistance, parallel Capacitance of sensor).

Does anyone know if there are some pre-made solutions like an IC or something, that can measure the charge and produce an output signal? It does not matter if the output is analog or digital, all I want is a good measurement of my charge and then get an idea how big the applied force is.

I know this is usually done with a charge amplifier, but since I don't know much about the sensor, I would like a already made solution so I can make sure there are no errors in my circuit that influence my measurement.


texts:
I am planning to interface a STM32H753XI to a 1400x480 display. Here is the reference manual. Now, the maximum resolution given for the STM is 1024x728. I understand that this is the maximum frequency the device can actually output.

Now my desired horizontal resolution exceeds the controllers 1024 pixels. I checked with the registers and they support 11 bit values (so everything up to 2047). Has anyone tried to interface a display with a larger horizontal resolution to an STM? Are the horizontal and vertical pixels a hard limit or is the combined pixel clock frequency the actual limit?


texts: Easiest (or cheapest) way to get both 5V and 3.3V on one circuit

texts:
I'm working on a circuit based on an ATTiny85 and I need accelerometer input.  I was looking at using an analog accelerometer (KXTC9-2050 that runs around 240 uA) because I have the extra pin and I'm a noob so I figured it would be better if I avoided the complexity of I2C right now.

Since that's the case, it looks like I need to drive my 8 LEDs (WS2812B) with 5V (the LEDs at full brightness should consume about 50mA) and my ICs with 3.3V.  I'll need to find a power cell I suppose (I'm open to suggestions).

Originally I said, "for space, I'd like to use a coin cell lithium battery so my supply voltage will be nominally 3V."  This seems infeasible because the maximum discharge rate won't drive my LEDs

On a related note, these LEDs are really bright at 100%.  Chances are good, they'll be PWM'd to less than 50%, they won't all be lit at the same time, and they won't all be full white all the time.  Their actual power consumption will likely be considerably less than 50mA.  But, I figured you plan for the peaks.  If that's wrong, please let me know.

Things I've considered:

The ICs have voltage ranges.  Maybe I can power the ATTiny and the
accelerometer directly off the battery and use a boost converter to
get the 5V that I need for the LEDs.  (Which I supposed doesn't really
answer the question because I don't have 2 regulated power rails).
I could boost the supply to 5V and use an LDO regulator for the 3.3 rail.
I could boost the supply to 5V and use an LED to drop the voltage down for the 3.3 rail.
I could use 2 boost converters.


texts:
Where is the 5V going from the 7805 regulator in this guitar amplifier schematic?

This comes across to me as a dead end part of the circuit.

I know the grounds are all linked but I am still struggling to work out what the purpose of this voltage regulator is and where the 5V is elsewhere in the circuit.


texts: What electronic component is this? It says "K103M" on top

texts:
What electronic component is this?
My Multi-function Tester says it is a capacitor with a value of ~8958 pF (= 8.9 nF)
It says "K103M" on top of it. Could this mean that it should be 10*10^3 = 10000 pF?


texts: How to calculate permittivity of a fluid

texts:
I am confused about calculating permittivity of a fluid.  Permittivity differs from one fluid to another.

$$\epsilon=\epsilon_r\epsilon_0$$

Since it is an electrical property combined with an electrical capacity, it is possible to measure it indirectly in a capacitive sensor. I have used a capacitive sensor to measure the electric relative permittivity factor of a dielectric medium, which can be expressed as a ratio of capacity \$C_x\$ of a capacitor whose space between and around the electrodes is completely filled with the medium, to capacity \$C_0\$ of the same electrodes in vacuum.

$$\epsilon_r= C_x/C_0$$

I know and measured \$C_0\$ value. I am facing problems with calculating \$C_x\$ of the capacitor whose space between and around the electrodes is completely filled with the medium.

I am using method as described below.

I am applying an A.C signal (125 KHz) to the capacitive sensor which is filled with some fluid; in response I am getting an A.C. signal with some phase difference. I am able to measure the amplitudes of the sensor input and sensor output signals and their phase difference also. I am trying to make an equation that will give \$C_x\$ value from above known values (\$V_g\$ (input), \$V_r\$ (output), \$\phi\$ (phase difference)).


texts: Generate constant voltage sources from the power supply using MOSFET

texts:
Suppose if I have a Vdd of 1.4V and I want to generate 1.2V and 1V constant voltages even when there are slight changes in the load values, is there any possible way of achieving this?
Well I tried doing this by using current mirrors and resistance ladders, but I couldn't achieve constant voltages from it because the load was changing. Can any modification be made to these methods or is there any solution for this?

Edit 1 :

This question has been asked in the perspective of IC Designing where I'm trying to lower the power dissipation my designed circuit by giving lower supply voltages to some of the components. Now the only way I can do this is if I can generate these voltages from Vdd considering I want only only one power pin in the IC.

Edit 2(3) :

The value of the current taken by the vdd is in the range of mA and the one needed for the 1V is around 80uA


texts:
I have a Creative Inspire 2.1 speaker system. The problem is that the right side speaker does not produce proper sound unless I try and turn the wheel to a particular position. I have unscrewed the controller and it looks like this:

What should I do?


texts:
Is it possible to detect a 3G mobile network without having the orthogonal code or the spreading code used in 3G?

By detect I mean pick up the radiated radio frequency from the mobile phone then see the peak frequencies then convert that to voltage.


texts: Associate std_logic_vector constant with input port VHDL-200X

texts:
I am trying to configure a chip over SPI interface using FPGA Spartan 6 Eval board. I just need to configure, I do not need to read the data from the chip, it will be done by another interface. Therefore, I want to send constants to register values of the chip.
Errors I got are:

Line 59: Cannot update 'in' object data_config

Line 40: Unit  ignored due to previous errors.

I guess because I have my constant associated with input port. I did not know I am not allowed to do that. Is there a better way to approach this? Thank you.

  --------------------------------------------------------------------
  -- Company: Quest
  -- Engineer:
  --
  -- Create Date:    11:11:15 1/11/2018
  -- Design Name:
  -- Module Name:    main - Behavioral
  -- Project Name:
  -- Target Devices:
  -- Tool versions:
  -- Description:
  --
  -- Dependencies:
  --
  -- Revision:
  -- Revision 0.01 - File Created
  -- Additional Comments:
  --
  ----------------------------------------------------------------------------------
  library IEEE;
    use IEEE.STD_LOGIC_1164.ALL;
    use IEEE.NUMERIC_STD.ALL;
     use ieee.std_logic_unsigned.all;

  entity init is
    port(

          user_clk : in  std_logic; -- 27 MHz external clk input to FPGA
          data_config : in std_logic_vector (7 downto 0);
        config_reg : std_logic_vector ( 7 downto 0);
          -- SPI 4 wires
          spi_miso : in  std_logic; -- Master in, slave out, just put high impedance since we don't read anything here, read out from LVDS
          spi_mosi : out std_logic; -- Master out, slave in, send config register values to TDC
          spi_ssn  : out std_logic; -- Slave select not, positive pulse to start, when LOW -> ready to shift of data in/out to/from device
          spi_clk  : out std_logic
      );

  end init;

  architecture Behavioral of init is

      -- Shift register
    signal shift_reg    : std_logic_vector (7 downto 0);
     signal count     : std_logic_vector (3 downto 0) := "0000";
  begin

          --* Config register settings *--
    config_reg_settings : process (config_reg)
      type config_reg is array (0 to 3)
        of std_logic_vector (7 downto 0);
      constant data : config_reg :=
                              ("00110000",
                               "10000000",
                               "00110001",
                               "00000001");
    begin
      for i in data' range loop
        data_config <= data(i);
      end loop;
     end process;
  ---------------------------------------------------
     spi_clk <= user_clk;
  ---------------------------------------------------
      -- * Master out slave in * --
     spi_process : process (user_clk)
     begin
      spi_ssn <= '1';
      if rising_edge (user_clk) then
  --      count <= "0000";
        shift_reg <= data_config;
        spi_ssn <= '0';
        if count < "0100" then
          count <= count + "0001";
          shift_reg <= shift_reg (6 downto 0) & spi_miso;
        end if;
      end if;
    end process;

    spi_mosi <= shift_reg(7); -- send out 8 bits at a time

  end Behavioral;


texts:
I am trying to build a voltage modulation circuit using an adjustable LDO and a uC switchable resistor network (to provide different Vout levels). I need the circuit to provide 4.9, 5.1 and 5.3V at the output depending on the resistor network set up by the uC.

I started the design using the NCP694 LDO; however I am noticing that the output capacitor in the circuit (2.2uF) is affecting my transient response and as such I can not modulate the voltage at the desired frequency (2kHz).

I have looked around, and all the LDO's I found needed at least a 1uF output cap, which I am thinking might be too high for my application. Do you happen to know of an LDO with a lower output cap requirement? or alternatively, is there a better solution for achieving the voltage modulation scheme that I need?

Thank you in advance;


texts: How to program the ADC10 on an MSP430G2553?

texts:
I am currently writing my first serious application with an MSP430 controller (specifically, an MSP430G2553) and I am a bit confused by the documentation as to how I'm supposed to set up the ADC10. I want to use it like this:

The signal (coming from a 100 kΩ potentiometer between VCC and GND) is connected to input A4 (pin 6) and is in range from GND to VCC
Once in a while (when the user presses a button) I want to sample the voltage at that input. One sample is sufficient.
I have enough time to do whatever is needed to sample input when the time to do so arrives.
I'd prefer to do this synchronously (i.e. without interrupts) as to not complicate the program logic too much.
The ADC10 should be turned off when I'm not using it to conserve power.
Neither the ADC10 nor ping 6 is used in any other way in this application.

How do I configure and use the ADC10 in this use case? I am programming the MSP430 in assembly, but an answer in C is useful, too.

Here is how I think the ADC is supposed to be configured:

ADC10CTL0:
  SREFx      = 000  (V_CC)
  ADC10SHTx  = 11   (64 clocks, we have enough time)
  ADC10SR    = 1    (50 kbps should be enough)
  REFOUT     = 0
  REFBURST   = don't care
  MSC        = don't care
  REF2_5V    = don't care
  REFON      = 0
  ADC10ON    = 1    (set to 1 after finishing the configuration)
  ADC10IE    = 0    (no interrupts)

ADC10CTL1
  INCHx      = 0100 (A4)
  SHSx       = 00   (sample and hold sourced from ADC10SC)
  ADC10DF    = 0    (no two's complement)
  ISSH       = 0    (no inversion)
  ADC10DIVx  = 000  (not too sure either)
  ADC10SSELx = 0    (is this the right clock?)
  CONSEQx    = 00   (single channel single conversion)

ADC10AE0     = 0x10 (A4 enabled)
ADC10DTC1    = 0    (DTC disabled)

I think the sequence to sample data looks like this:

set ADC10ON to 1, ENC and ADC10SC to 0 and configure all the registers.
set ADC10SC and ENC to 10 to start conversion
wait for 64 + 12 + 1 = 77 cycles for conversion to finish
read result from ADC10MEM

Is this sequence correct? Are the settings correct?


texts:
I'm trying to understand the concept of a floated voltage, and why it is needed in some cases.
For my own case, I am using a variac connected to a rectifier to provide a DC voltage for a circuit, (charging a large capacitor for discharge). The circuit needs a ground connection, but connecting a ground to complete the circuit also grounds the rectifier, which I am told will damage the rectifier.
(I do not fully understand why this is the case, and would like to find out more.)

But it was suggested to me to use an isolation transformer before the variac and to float the voltage, and in this way rectifier would be kept safe. I would like to know understand how this works.

(I am aware another option could be to add a switch and just disconnect the rectifier from the capacitor, but I am more interested in understand the above).


texts: "Amplify" LED-Controller to handle higher currents

texts:
I have a bunch of LED controllers which I am currently controlling over WiFi. Unfortunately, they are all rated for very small currents of about 2 Amp (ish).

Each LED Color gets driven with a simple N-Channel Mosfet as a low-side switch.

My question is: Assuming my N-Channel mosfet is properly rated, can I drive a load which is much larger with this setup? The PWM Generator symbolizes my LED-Controller, which should pull the Base of the PNP Transistor to Ground since it is just a low-side mosfet. The values of the resistors are all default, I am aware that I have to tweak them properly. The LED on the right hand side of the schematic is basically an entire LED-Strip with three LEDs in series and a huge amount of those three LED Groups in parallel.

Additional technical information:

The maximum current the LEDs should draw is about 6 Amps.
I'm planning to use an IRLZ34N with heatsinks. Probably way overkill but I have plenty of those so... why not.

The default PWM Frequency of the controller is 1kHz but I'm thinking about patching that to a higher frequency. I know the chip supports it and right now my power supply gives of annoying high pitched noises even though it is a name brand.
The accuracy of the PWM signal isn't critical at all, it's just for some ambient lights. Since I want to dimm them properly, the dynamic range of the duty cycle is very high, so basically 0-100%ish. Usually I won't run them close to 0%. The brightness isn't linear so everything below 40% is almost like switching them off completely.

Will the PWM dimming still work properly?

Everything has a common ground.

simulate this circuit – Schematic created using CircuitLab


texts: Busy-wait sleep function has incorrect timing on NIOS CPU

texts:
I have a Qsys system which includes a NIOS II/e CPU (which is the only master on the bus) and a 36kB chunk of 32-bit internal RAM. The RAM is configured to have the minimum read latency (which is 1 cycle). The whole system is clocked by a single 50MHz clock.

I'm trying to use the usleep function to wait for 1 second and use clock to measure the time:

#include <sys/alt_stdio.h>
#include <unistd.h>
#include <time.h>

void main(void) {
    clock_t start, end;
    start = clock();
    usleep(1000000);
    end = clock();
    alt_printf("usleep(1s) takes 0x%xms\n", (end - start) * 1000 / CLOCKS_PER_SEC);
}

Surprisingly, I get a value 0x592 (1426 DEC), which is not even close to 1 second. Toggling a pin before and after usleep and measuring the time externally confirms that the delay is indeed close to 1.4s.

I understand that busy-waiting is affected by RAM latency and bus arbitration, which I carefully tried to exclude. What is the expected system configuration on which usleep works correctly? Is there an alternative delay function with μs resolution which would work on the configuration I have?

To answer the clarification request, all durations are wrong by about the same factor (1.4), which I suppose depends on the hardware configuration. Simply multiplying by the corrective factor is not a solution for me, since this is for a project which should allow the users to run Arduino code on any FPGA capable of implementing NIOS.

The usleep implementation I'm using comes from Altera "Small C library", AFAIK it's a clone of newlib. Compiler options from "Hello World Small" sample project reproduce the issue. I tried several combinations of options, and none of them fixed the problem. Again, since this is for a library, I'd like to find a solution which works with different (reasonable) compiler options.


texts: Can I use this Anker Astro 3e to power my arduino through the usb?

texts:
http://www.amazon.com/gp/product/B009USAJCC/ref=oh_details_o00_s00_i01?ie=UTF8&psc=1

Will there be any electrical problems? I'm building a arduino controlled car (with a chassis like this:
 http://www.ebay.com/itm/261210375016?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649) and I'd like to power the arduino and the motors from the anker lithium ion battery pack. I'm thinking just plug the thing into the arduino and let it draw power. (Does anyone know what I'd need to convert the 2nd usb slot into a power source for the 4 electric motors?) Any problems with this design?


texts: IR rays over carrier frequency of 34Khz?

texts: How is IR rays that have carrier frequency of ~1014 Hz generated by GaAs in remote control carried over carrier frequency of 34Khz to the sensor?


texts:
Help me understand the role and effect of an inductor used in the following electrical circuit.

The circuit in question is a power supply circuit for around 50 servers in a data center. The circuit uses a MOSFET transistor for commuting the power provided to the servers. In order to protect the transistor, the apparatus must be able to evaluate the connected charge in case it might be a short-circuit or too high of a capacity, as this will destroy the transistor.

For this purpose, an inductor is connected in series with the circuit, but I fail to understand how this addition fulfills the intended role.


texts: Inaccurate voltage readings on an esp32 as opposed to multimeter

texts:
I am working on detecting the amplitude of a signal coming from a guitar pickup. I am using an esp32 and an LM386 module for amplifying the signal.
I get quite stable readings with a multimeter, but the readings on the Arduino IDE show peaks and also peaks come when no signal should be there.

Here is a link for short videos of both the esp32 readings and the multimeter:
https://drive.google.com/drive/folders/1gpvkN_sz627jG0TNPpUps82105EB89OF?usp=sharing
Thanks!
Simple code:
int ampedVoltagePin = 12;

void setup() {
  pinMode(ampedVoltagePin, INPUT);
  Serial.begin(9600);
}

void loop() {
  Serial.println(analogRead(ampedVoltagePin));
  delay(100);
}

Diagram:


texts:
I have these common eBay 433 MHz module pairs pictured below and am trying to hook up an external antenna.

On the TX there is a little hole marked ANT which works for that.

On the RX pictured (XD-RF-5V), there is a similar hole with no markings that increases range if I hook it up to an antenna.

So I was looking at making dipole antennas for them, but I got confused when trying to find the ground to connect up to that part of the dipole antenna.

You might be thinking easy trace the pin marked GND, which I did, and while doing that I traced the 'antenna' hole I'm using.

The hole is connected to that little copper coil and then onto the SMD components 'above' it.

But it confuses me that there is 0 ohms resistance (as if it's connected) to that GND ground pin...

So how can it work as an antenna if it is connected to ground?

And as a second question, wouldn't I have to take into consideration the
length of that coil in my antenna length calculations? What is it
anyway? Could I remove it?


texts: Electrical Safety: Grounding of multiple actuators and control board

texts:
Im working on a prototype involving multiple motors, and control boards (PCB), and the device's skeleton.
Reading the Electrical Safety with which there are three types of grounds chassis, signal and earth. Am I to connect my control board's ground(5V) and motor's ground(12V) to the prototype skeleton?
How can I make the best grounding for this? I would like to prevent ground looping from happening.
References I read:
https://www.analogictips.com/faq-ground-rules-earth-chassis-signal-ground-faq/


texts:
I was trying to implement a H-Bridge circuit but had a lot of failures. I'm not really good with electronics, just some basic knowledge.

So I've started by creating an buffer to switch the full voltage of a 12V power supply by using NPN and PNP transistors. This is the switch for the power supply.

It works like a charm. Just as I expected.

Then I moved this switch into the H-Bridge circuit to switch my 12V supply On/Off on each side of the bridge. So I added 2 transistors for the bridge to ground the current. But I'm having a massive voltage drop and I don't know why. I hope you could help me with this. Here is my bridge schema.

The bridge logic works fine but I expect to get 12V instead of 3V on the motor it self.


texts: I have some confusion in noise signals and their nature. Can any one explain how the nature of noise signals is. Is noise a random process.


texts: Integrating MAX31855 with FPGA to make thermostat

texts:
NOTE: I am newish to FPGA programming. I have only taken 1 university course for it. I am looking for direction on where to start, not for someone to do it for me.

I bought a MAX31855 k-type thermocouple ADC amplifier. I want to hook it up to my FPGA (Altera DE0) through the GPIO pins. Adafruit has some code they've written to implement it. Their code is written for someone using an arduino board. Looks pretty straight forward if I had an arduino, but I dont. I am wondering what this code is written in.  Doesnt look like verilog.

https://github.com/adafruit/Adafruit-MAX31855-library/blob/master/Adafruit_MAX31855.cpp

Would I be to cut and paste that? If not, does anyone have info on where to start with this?


texts: Charging batteries and how voltage affects it

texts:
I know that when I am charging a battery, we need higher voltage than the battery is rated at in order to "push" current into the battery itself. Right? OK. Since that is true, is it possible for me to use a lower voltage, but into the separate battery packs? I WILL EXPLAIN. I am sending current into a 10 volt light bulb. The batteries I am using to send that current are eight 1.2V rechargeable aaa batteries (NI-MH) put into series. BUT I am using 3 battery holders, 2 of them hold 3 batteries, and one holds 2 batteries, as shown on the following pictures. So basically these battery holders are put into series. Now, when I charge them, how is the voltage distributed amongst all 8 batteries? Like, is the 5 volts going to go to each battery holder charging them individually, even thought they are in series? Is there a way I can charge this battery pack with 5 volts?
If this doesnt work, how about this?:  Will each aaa battery get 5 volts, or each battery pack get 5 volts, or my whole setup get 5 volts? The reason I am asking this is because I know that in order to charge a battery you need higher voltage than it gives out, and a diode won't solve my problem of my setup won't work.


texts:
I just ordered an Fingerprint sensor I followed the schematics and made it work with my Arduino.Now I want to connect it directly to my computer, the device has ( GND, RX, TX, 5V ) I have a prolific USB cable witch has outputs (RX,TX,GND) .

Is it possible to connect the USB Prolific cable with the device ?

I know that USB outputs 5V but how can I get power if the prolific cable does not have such output?


texts: What is the transmiting API for master in I2C for EFR32

texts:
i could not find in the API shown  bellow the functions related to sending data or communicating with a slave in general,as shown in the diagram bellow.is there something like this?
Thanks.
https://docs.silabs.com/mcu/5.4/efr32fg14/group-EFR32FG14P-I2C-BitFields


texts:
is there any systematic way of trasforming an ASM chart to a sequential circuit immediately? I mean, given that the 'State Block' can be represented by a D flip-flop; 'Decision Block' is equivalent to two AND gates and so on.

I tried mapping these elements directly but I don't know how to do the conections properly. I usually draw impossible arrangements like this (this is just a part of a sequence detector):


texts: Dashed and Solid Line Signs on a Battery

texts:
What is the meaning of the solid and dashed line on a battery or charger? I will give two examples below and the first one is a 4-cell battery and it says "7.6V [dotted/dashed line] 54.4 Whr 7150 mAh". How can I calculate one cell's capacity? And what is Li-Ion Polymer? Isn't it Li-Ion or Li-Poly? How can be possible that using two different battery types on a single battery?
And the second one is a charger and it says "Output: 19V [dotted/dashed line] 3.42A"
Sorry for the qualities of the pictures but these are the best ones that I could found.


texts: What would be a good replacement for a set of HR6 batteries?

texts:
I need to change this OEM set of batteries1 because they are not holding a charge any longer. I am not familiar with rechargeable batteries.

My understanding is that I should be able to swap the OEM batteries with two 1.2V 1300mAh AA batteries2.

Would it be correct?


texts: stm32f407: usage of PSC in IrDA Low-power mode

texts:
Finally, I received my stm32f407 board, and a sample USART C project. The project comes with a Stm32f4xx_usart.c file (not HAL driver).
I want to figure out what the usage of PSC register is in IrDA Low-power mode by reading the driver, but only found a function called USART_SetPrescaler, which is just a simple wrapper of a "write data to GTPR register" command. So I can't infer anything from it (at first I was thinking there might be such a driver function that we pass in info such as baud rate, etc., and the function does everything for us including writing to PSC).
The reference manual describes PSC as:

I thought PSC is used to set baud rate in IrDA Low-power mode at first glance. Then I wrote a small program with a fixed BRR (BRR=0x40) and all other settings, except that I changed PSC each time, from initial value 0x1, and incremented by 0x1. With the oscilloscope, I found that:
when PSC is 0x1~0xa: baud rate not changed, the waveform shows a equal bit time, only the width of pulse increases ~40ns each time linearly.
then I keep increasing PSC: the bit time varies greatly. It's like the output of a digital odd divider -- some cycles (bit time on the TXD line) are wider, while some are much narrower. And the width of pulse changed nonlinearly.
The PSC has a bit width of 8, and I havn't tested much right now. I'm really confused, and have no idea what the function of PSC is. Any help would be appreciated.


texts: Thermocouple amplifier and cold junction compensation

texts:
I am trying to design a thermocouple amplifier with cold junction compensation. I already designed a simple amplifier for the thermocouple using LM358. Note that I can built this entire circuit using only cheap and easy to find components, such as low power transistors, LM358, LM324, resistors, diodes, pots, trimmers. I know that I could buy from the internet modules, but I can't at this moment .
I also need a cold junction compensation, which should be connected to Arduino, to an analog input.

Schematic: https://ibb.co/Sfs9dPX


texts: I created this circuit and at first all the wires were green but when I copied it out of the main folder into another one, the wires turned blue. I've tried messing around with it and looking up what the problem is but I cannot find a solution. The exact same circuit was working before and I don't understand why the wires are blue which are coming directly from the pins, they should definitely be green.


texts: Is ther a standard circuit/component to control the temperature 500W resistive heating element from a PCB?

texts:
I have a 500W (230V) cartridge heater element and a K-type thermocouple. I want to use the feedback from the thermocouple to be able to vary the temperature of the cartridge heater. I have no concerns about being able to implement the thermocouple circuitry and software, however I have never used a high power heating element before.

I'm looking into the control of the element. I personally don't have an issue with an on-off control (as in, I'm okay with applying some hysteresis and having, say +/- 10°C from the desired value, or using PWM), however maybe there are some other considerations as to why this wouldn't be a good idea (switching life cycles for example).  If there is a component to safely vary the power to the heating element, so I can implement PID for example, then I would also be interested in that.

As I want to control the heating elements from a microcontroller (preferrably 3v3, but can level shift to 5v if needed), I've been looking into relays. However, I am struggling with the power requirements - from what I find, 500W seems to be a lot of power for a PCB based relay (although since I've never used a relay before, maybe I am misinterpreting the specifications). I'm also concerned about the actual traces on the PCB - I'd much prefer to have the relay controlled by PCB traces but the heating elements just connected to the relay by wires, if such a device exists.

I've looked into latching, non-latching, solid state relays, SCRs, triacs, but I feel like the more I look into it, the less sure I am. I'm now at the point where I feel like there must be a standard way to do this, but I'm just getting lost in the sea of options.

So, is there a standard circuit/device to safely control the temperature of 500W (230V) heating element using microcontroller-level voltages? The cheaper/simpler method is usually better in my eyes, as long as it's safe.

EDIT:

Thanks all for the comments and answers so far. Looks like I'll go with some type of relay, and possibly some backup protection if I want to use a latching relay. One of the main issues I'm having with finding a suitable relay is geting the specifications correct. For example, the following is taken from a relay datasheet:

The first thing I see is that max switching voltage and max switching current are both high enough - great. Then I saw the rated load box, when confirms this. However, what confuses me is the 'Max. switching power' box. I'm already a little bit hazy on the difference between VA and Watts, but the fact that at has a maximum of 300W, while my element is rated at 500W, confuses me. Can anyone help explain this?


texts:
I am designing a PIFA antenna in CST microwave studio.  I have found something peculiar that I do not quite understand.  My antenna resonates at 1.6 GHz, and when the substrate (FR4) is very thin (0.5 mm), I get an S11 of about -20 dB.  The realized gain at this frequency is -12.5 dB.  If I make the substrate thicker, the S11 resonance gets worse, and the gain gets better.  For example, making it 3 mm (instead of 0.5 mm), the S11 went to -4, and the gain went to -6.

Can anyone explain why this is?  I thought realized gain takes into account mismatch loss, meaning S11 should be a factor. If the S11 gets worse, how is the realized gain getting better??


texts: How to derive the solutions of the Differential Equations when using convolution?

texts:
I am currently learning convolution (which is not the easiest topic for sure). Just as by many fields in electronics also here are differential equations involved.  With this (what I have seen until now) there are two types in convolution, namely:
1.) y'(t)+ay(t)=bx(t) *
2.) y'(t)+ay(t)=bx'(t) *
*With x(t) is the "unit impulse function" and  y(t) is the "impulse response"
Then in the book out of nowhere they give the solutions to these differential equations, namely:
1.)
2.)
1.So the first one is kind of standard and I know what they are doing, but where did the x(t) goes. is it treated as a 1 with the integral or something?
2.The second is some random formula for me ;) , can somebody please give an step by step solution by how to get from the differential equation to the solution of both the 2 functions?
P.S. The delta t in the second solution is equal to x(t)


texts:
I’m an electronics newbie, so I’m trying to use a few IC's to check my understanding.

At the moment I’m trying to use a 74LS259 8 bit addressable latch. I’m trying to get it working without a micro-controller first to ensure that I understanding the wiring 100%.

But I am having a problem understanding the E and C pins … (see below)

I’ve wired it as follows:

A0-A2 - Address inputs - wired to a switch and the +5V Q0-Q2 - Outputs
Each wired to a LED and a 220ohm resistor
Q3-Q3 - Outputs - Not Wired (Is this a problem should I wire them to the -5V instead)

The issue I has is understanding how to wire the E (enable) and C (clear) pins.

The datasheet says that to select the “addressable latch” mode I should have:

E - Low
C - High

So I’ve wired E to 0V and C to +5V.

I then try to “write” a bit by taking A0 high and then D (data) high but this does not work.

I suspect that I have wired E and C wrong. I’ve searched around but I can’t find any circuit diagrams that could help me…

Can anyone assist? What am I doing wrong here?

Here is the circuit diagram at CircuitLabs:


texts: Why is the CAN bus always busy (microcontroller)?

texts:
I'm trying without success to perform CAN bus communication between an microcontroller and the host (my computer). My question does not depend on the microcontroller, but on the CAN Bus (classic CAN).

My application tries to send a frame each (5 ms, 10 ms, 100 ms). I have a simple scheduler that execute tasks where I call the function can_write(HwObject,Frame) to write the frame to the bus.

However, the first frame returns OK and it's received at the host, but after that (and for all the following frames) the function returns busy, and I keep seeing the error counter increasing without any frame arriving at the host. Finally the node seems to go into bus off mode.

I want to know what are the main reasons for that: I'm using the same baudrate, 1 Mbit/s, on both sides, but I also tried different ones, but without success to see any results. I have looked around registers to see what could be the issue. For example I get:

The bus detects a transmit abort request.
The channel enters to halt mode after bus off.
The bus is in passive mode.
A channel bus error is detected.
Error warning is detected.
Overload is detected.
A bit stuff error is detected.

PSS: I'm following the AUTOSAR Standard: The CAN specification can be found at:
https://www.scribd.com/document/160011317/Autosar-Sws-Candriver

But I can't find what causes this issue. I think it is due to bad synchronization!


texts: The best way to test a solar panel generation

texts: Is there any way to test how much a solar panel on a given position can generate for let say a day or few days. Like a multimeter that can automatically test the wattage days example? Or create a circuit to do that? Anyone recommend anything?


texts: Why are the "common" resistors and capacitors rated the way they are?

texts:
Very newbie question here...one to which I've been unable to find an answer in any of my books or online resources.

Whenever I see a capacitor/resistor assortment that features the most "common" ones (which, I understand can be quite subjective), they tend to come rated in powers of 1, 2.2 and 4.7. What's magical about those numbers?

Is that some mathematical relationship in Ohm's law of which I'm not aware? Is it some logarithmic progression for some OTHER electrical engineering formula that I've not yet encountered? Why is there such a huge gap between 4.7 and 10.0, why isn't there a 7.1 or some such? As someone who a scary uncanny knack for solving "find the pattern in this series of numbers" puzzles, it's killing me that I can't figure this one out. :)


texts: HC-SR04 Ultrasonic sensor below a grid plate

texts:
I want to use the ultrasonic sensor under a metal grid plate like below (just 1 of those plates instead of 3). The sender/receiver will be under (partly inside) two adjecent holes (hopefully it fits) and point upwards. The reason is to detect if someone (a person) steps on the plate.

The height of the plate is about 1,5 cm and the height of the receiver/transmitter is about 0,5 cm (if I leave some space for the enclosure), maybe even less space.

In the diagram below I showed hopefully clear enough what I want.

What I'm worried about is that the receiver picks up the distance to the plate (the red lines), so it will always received just a centimeter or so.


texts: Why does my bluetooth dongle use more current when paired then when idle?

texts:
I have a bluetooth dongle which is connected through USB to my PC. I wanted to measure the current drawn and hence I connected an ammeter in series with the 5V line and am measuring the current. I observe some strange readings:

When I pair it takes up less current then when in idle state. This seems strange and I would like to know why.


texts: According to Moore's law, transistors are getting double every 24 months. But now, we have reached the transistor size limit which results in leakage current. Then why can't we increase chip area size, so that we fit more larger transistors?.


texts: Is charging 18650 lithium ion cells with lower current better?

texts:
I have a 3p12s 18650 Li-ion battery pack that I use for my e-bike. I charge it with a balance charger. I know that charging with too high current is bad for battery life. But is it "the lower the better"? If not, is there any recommended minimal charging current? Is charging at 0.1 C safe? My only goal is to prolong the battery life (number of cycles). I charge it only at night so I don't care about it taking long time.

In the data sheet of the cells I use (Sony US18650V3) there is only specified maximum charge current 1 C. It says nothing about minimum charge current. What's more, I've never seen any batteries data sheet mentioning "minimum charge current".


texts: Piezoelectric transducer impedance and phase measurement

texts:
I have a circuit comprising of LT1210 current feedback amplifier (supply voltage = +/-15V, gain = 4) and its output is connected to a transformer (RM10 N97) with N=16.6 (150/9) which is further connected to a piezo transducer and a 50 ohm resistor (shown below).

simulate this circuit – Schematic created using CircuitLab

I am sending a sine wave sweep input 1Vpp from 100kHz to 400kHz into the op amp. When the output does not have a piezoelectric transducer (Fres = 250kHz) connected, it is a clean sine wave. However when I connect the transducer, the output looks distorted between 100kHz to 200kHz (as shown here, point CHA on the schematic):

and improves thereafter.

I have tried changing the gain of the amplifier from 9 to 4 (present gain) but it still looks distorted.

Because of this distorted output between 100 and 200kHz, the measurements look like this:

As seen here, the phase and impedance measurements are not correct from 100kHz to 200kHz.

Note: I have used 16.5uH inductor in parallel with the transducer.
Also the schematic is just a drawing, I have not simulated it.


texts: AC vs DC and ELF - extremely low frequency

texts:
given :

  How do static fields differ from time-varying fields ? A static field does not vary over time. A direct current (DC) is an electric current flowing in one direction only. In any battery-powered appliance the current flows from the battery to the appliance and then back to the battery. It will create a static magnetic field. .... In contrast, time-varying electromagnetic fields are produced by alternating currents (AC)

are thus extremely low frequency -ELF - fields a property of AC current only and not of DC?, that way when an electrical appliance such as a phone/tablet/laptop runs on battery only  does not emmit ELF, but on the other hand when plugged into a socket becomes subject to AC, thus emmiting ELF ?


texts:
I have a Atmel microcontroller with 0-5V DAC output and I want to shift it to 0-16V (16V max. normal between 11-16V).
It need an output signal with max. ~1mA, short protection and reverse polarity protection.
What is the best way to do that?


texts: How high is "high impedance" on this chip (CD74HC125E)

texts:
I'm trying to interface my electronics with an existing remote. The remote requires me to set one of its pins to either low or nothing (not connected) to activate it.

While getting the "low" value is easy, I have more doubts about the "nothing". It currently works if I use the "high impedance" state of a CD74HC125E chip. But as the remote consumes about 1.5 micro amp, I'm worried that the "high impedance" state might be a little too low sometimes.

I tried reading the datasheet, but I'm still a newbie and I can't figure out where to read this impedance. Any help?

Datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/27003/TI/CD74HC125/+Q51QWUPGZwEYtKhBYw+/datasheet.pdf


texts: Is there an metric equivalent to the NEMA step motor frame sizes?

texts:
I just took the axis motors of my EMCO F1P CNC mill and measured them to figure out which frame size they have.

The square flange is exactly 60 x 60 mm, and the distance between mounting holes is exactly 50 x 50 mm. This rules out any NEMA frame size.

I want to replace the motors, so my question is, is there a similar standard for electrical motors to NEMA that is based in metric units (European/German perhaps), or do I have to make adapter plates to fit NEMA motors?


texts:
I would like to know if this is a sensor and the name of it if it is possible. I post two pictures, sorry about bad quality of them.

In my opinion it works sending different signal if something is between little "crystal sticks" into the dark of the black box.

Would be wonderful to know the schema to connect it to an Arduino, also if is mandatory to add some other component like resistor (I should post another question for this, may be)

Both components are very similar with a few little differences.

Thanks a lot in advance.


texts: Slip Control vs Constant V/F Control for 3-Phase ACIM

texts:
I am trying to understand how is Slip Control different from Constant V/F control. If I need to control the speed of 3-phase ACIM then its slip would obviously change with its rotational speed then how can we say that its constant slip control?

And if I compare the two techniques then which one gives higher torque at slow speed?


texts:
Please, help me to determine the polarity of a RWA1C101MEG capacitor. I see a fat stripe on one side of the capacitor:

Is this a positive or negative terminal?


texts: How do I determine safe distance from a choke to prevent accidental coupling?

texts:
In most of my power converter applications, I end up with a choke of some description, somewhere in a steel chassis. I have seen and heard tell of situations where the choke couples to the steel of the chassis. In some cases, the windings heat up more than desired, as does some part of the box. In other cases, the box itself has the powder coat baked off the metal. The general solution has been to keep the windings away from the steel, as well as any core gap.

However, "away" is a vague term. Is there any rule I can follow to determine the safe distances required to prevent coupling? Example situations include:

Distance between winding and steel box
Distance between choke gap and steel box
Distance between air core choke and steel box

I imagine that an exact solution is dependent on a detailed geometry of the system, so general rules are preferred.


texts:
I am trying to build a skipping rope jumps counter. My preliminary design consists of an LDR, a laser diode, and sn Arduino.
Basically, the LDR and the laser diode are placed exactly opposite to each other, and whenever the LDR detects some obstruction it increments, thus allowing me to count the number of jumps.
My concerns are:

How small can the obstruction be? (I guess it depends on the surface area of the LDR, itself.)
How fast can I go? (Will the LDR be able to detect a jump frequency of 300+ jumps/minute?)

I would also greatly appreciate it if you can suggest any improvements.


texts: Simplest uni-directional level shifter (3.3V -> 5V)

texts:
I want to drive a WS2801 LED strip from a Raspberry Pi GPIO.

I have connected the MOSI and CLK pins directly to drive the LED but it is not working as the WS2801 datasheet says that a high level is \$0.8 \times V_{dd} = 0.8 \times 5V = 4V \$ (I am guessing).

I know that there are assembled modules available on internet (such as this: 4-channel I2C-safe Bi-directional Logic Level Converter) but before buying any of these I will like to be sure that this will be the right solution to get it working so I want to purchase "simple level shifter" on any local store.

What I am looking is the simplest level shifter that shifts the voltage from 3.3V to 5V (uni-directional). By "simplest" I mean that it has the least number of components (resistors, capacitors, etc.) as possible, maybe a single IC in a DIP form so I can use it in a breadboard.


texts: What can I put a kilowatt into? (Or: help me save my hairdryers)

texts:
TL;DR: I need something to discharge roughly 160A at 14V into, or 2.24 kilowatts. Any comments, or answers, with either a) something I can dump a kilowatt into, b) some way I can modify a common item to take 2kW DC at 160A, or c) another way to measure battery max continuous discharge current would be greatly appreciated.

Unfortunately, a large number of other people on the Internet that have this problem are dealing with far fewer amps (160A is pretty crazy.) Thus, any comments to "just google it" or that it is similar to previously asked questions aren't appreciated.

I recently bought a large battery, a Hobbyking Multistar 16000mAh 4 cell LiPo battery. Unfortunately, HobbyKing is notorious for inflating its products' specifications. The max continuous output is variously listed as 15C (which would be 15C*16000 mAh = 15C*16Ah =240 amps) and 10C (which would be 160A). The battery voltage should range from 4.0V to 3.2V per cell during use, so 16V to 12.8V.

I'm hoping that the continuous output is at least 10C, or 160A, but I have no idea what is is. People variously report the actual outputs of Multistar batteries as ranging from 10C to 3C, and there's a lack of actual test data and far too much anecdotal data. I'm hoping to test this myself by dumping 2kW into something and measuring the current the whole time.

Basically, I need something to discharge roughly 160A at 14V into, or 2.24 kilowatts. I've looked up things that take power in the range of a kilowatt, and found that microwaves (~1kW), ovens (~1.5kW), power tools (~500W-2kW), projectors (400W-4kW), and hairdryers (~1-2kW) are my best bets. I'm not exactly sure how to plug my battery into any of these though. Obviously the battery puts out ~2.2kW DC at 160-ish amps. I have no idea what my hairdryer wants, or how to get it to take DC, without a large amount of work. I also understand that this would be far into the range of the mad scientist, and would probably result in a cool explosion.

Is there an easier way to test my battery's capacity? Within reach I have a LiPo battery charger (max discharge rate 1A unfortunately), a decent Fluke, a lot of household equipment, a number of power supplies, a 400W projector, and a workshop with a decent number of power tools/electrical equipment.

Any way to test my battery would be greatly appreciated, including ways to get my hairdryers to take DC, ways to discharge two kilowatts into something that's not an appliance, and any other ways to generally test battery discharge characteristics.

[edit] I know that putting a kilowatt into household appliances is pretty impractical and dangerous if you're stupid. I also now know that it's also damn hard. I've now switched to wanting to make, or buy, a large resistor. For the safety police, I know how dangerous 2kW can be. I have always intended that any test -- be it on a proven resistor that should work fine or a household appliance -- would be conducted outside, on nonflammable ground, with fire extinguishers, where if something blows up I can make a pretty video and share it with the Internet as opposed to dying from electrocution and burning down my house. I also know how 2kW can melt things and have handled energy on this scale before. I'm not an electrician and I know my limits, but I do know how to handle 2kW to the point where the worst that could go wrong is a few hundred bucks of stuff down the drain and a pretty explosion video on Youtube. I am acutely aware that there is a very high chance that the battery, or whatever I'm sticking 2kW into, might explode, and I will share the video with you all when (if) it does.


texts: How much of the rated capacity of a lithium ion battery can I discharge?

texts: If I have a 90ah lithium ion battery pack can I safely discharge all 90ah of it or will the bms not let me? I've read that the bms only let's you use 80 percent of the rated capacity. So is the real usable capacity 80 percent of 90ah which is 72ah?


texts: Electronic device that can pick up on audible alarms in house, to be used to trigger other action?

texts: I have done some searching for products that can do this but am having a hard time finding anything. I have a number of different alarms in my house, such as smoke alarm, leak detection alarms, carbon monoxide, etc. They are all basic, low-tech audible alarms. I'm not able to invest in a bunch of new alarms that have SMS / phone calling capability. I figured there must be some electronic device that can pickup on audible alarms and then be able to trigger an action, this way I could have one of these devices that would pickup any of the alarms, as they would all be within a certain audio frequency. Any info is appreciated. Ideally I'm hoping to get a device that can either make a phone call or send an SMS when something occurs, however, I'm willing to take that part on as a project (I'm a software developer so interested to learn a bit more about electronics). Thanks for any info.


texts: How to drive a high-side logic-level power MOSFET?

texts:
simulate this circuit – Schematic created using CircuitLab

Could you please tell me if it is possible to drive a high-side power MOSFET IRL40B209 with a high-speed logic gate optocoupler SFH67XX by tying the optocoupler GND to the MOSFET source.

Thanks