texts: Differences, uses, and theory of volatile and nonvolatile memory?

texts: I understand the basics of volatile and nonvolatile memory. Volatile memory requires a constant power supply to retain data whereas non-volatile memory does not require a constant power supply to retain data.  What I would like to know is this: are there any other major differences in terms of performance, speed, size etc?  In addition, what uses do each play in a computer?  Lastly, how does each work?  Thanks in advance for all answers and comments.


texts: Simple way to create a disturbance on DC power

texts:
First of all, i must say that I am a software engineer, with very-low to no experience in circuits designs, and a very rudimentary understanding of electrical engineering and circuits. 101 really.

For a software project I am playing with I have built a small physical gauge simulator using some ready-made cheap 7-LED and old needle voltage and amp gauges.
They are all powered from a standard DC 24v 3A power supply and I am using a potentiiometer to make the values change manually when i need to change them.

My challenge is the following :
Is there a simple way, without special components / devices (NOR MCU arduino/pi to make the gauges "jump" automatically and basically mimic the operation of me fiddling with thee potentiate ? Basically some kind of a DC oscillator - but random jumps are ok.

I do not have an the option (time-wise) to buy special components but I do have a lot of standard ones, ranging from capacitors, to resistors, DC power converters, diodes, LED's, Fuses, transistors (PNP,NPN, mosfet), coils, magnets photoresistors, humidity sensors etc.
On the device level I have some low-voltage motors, steppers and solenoids.
There is a bit of everything in the very-basic range of stuff.

Is there a simple circuit that can help me achieve this "jump" in the power without any code ? ( funny question for a coder - I know. but there IS a logic behind the project :- )

EDIT I :
Here is a picture for better understanding .

EDIT II :

I ended up using a combination of 2 solutions :

A - I took a solenoid that was producing heat and connected it to a relay via and NTC ( PTC would work the same I assume ). The NTC got heaat from the solenoid and functioned like a "gate" for the relay, which also started a small fan to cool the solenoid again. The solenoid operation also made the amp jumps .

B - I Friend brought me an ne555 which I connected to relay. ( but that's an oscillator - which was a few days later )

Although these primitive methods work, I would still like to hear other advice on how to achieve that in some other way .


texts:
Looking online for small SSD1306 OLED screens to use with Arduino over I2C, I find products that look like this:

The sellers don't offer datasheets - and the product descriptions don't say anything about whether the SCL/SDA lines are 5V tolerant.

Based on what is visible in the pictures, there appears to be a regulator for the VCC line - so this will indeed be taken down to 3.3V or whatever that screen needs to work. But the rest of the board is just resistors and capacitors - no level-shifting in sight.

I worry that these sellers simply play on the tolerances of these screens - and will either fry immediately with 5V SDA/SCL signals, or will age quickly and fry a bit later.

What do you guys think?


texts:
If I have an MCU pin connected in between 2 resistors (a voltage divider) how does the MCU pin actually detect the voltage? I am using an ATMega328 and reading the voltage from the divider by an ADC enabled pin.

I believe my understanding is broken but here is what I'm thinking...

the pin is floating but is set for input (has internal pull-up enabled)
the top resistor in the divider takes some voltage (voltage drop)
now, the wire that connects the middle of the voltage divider to the pin has a potential of x volts (it could potentially push by x volts)
BUT, no current will flow through the connecting wire to the pin as the pin isn't at ground (there is nothing to "pull" the current towards it)
if no current flows to the pin, how is voltage detected? If the current is 0 then according to Ohm's Law voltage would be 0 too


texts: Placing bypass capacitors after VCC reaches the IC

texts:
I have a question about bypass capacitors and their possible placements.

I am designing what I hope to be a double sided PCB, which has the VCC and the vast majority of the data lines on one side, with the majority of the other side as a GND plane that the first side can via into as needed.

I have found a picture of a PCB online which is doing similar things that I want to achieve, which is interface mostly 3.3V parts on a PCB designed to mate with a 5V host.
As such, it has 3 SN74LVCH16245A family ICs to do signal level translation from 5V to 3.3V and visa-versa.

I found the way the designer did the bypass capacitors to be elegant - it appears that there is a small VCC plane created underneath the SN74LVCH16245A ICs, and that the VCC lines on the ICs are connected to that plane on the opposite side of their pins, with the bypass capacitors then connected to the pin on it's normal side, and then the other connection of the bypass capacitor neatly vias to the other side for GND.

I have drawn a box over the SN74LVCH16245A ICs in the image below:

I have made a diagram of what I think is going on below:

My question is, is it ok for bypass capacitors to be placed after the VCC on the PCB reaches the VCC pins on the IC?
I ask because I have never seen bypass capacitors placed like this, or advised to be placed like this. In every illustration I have seen, the VCC line comes towards the VCC pin on the IC from the normal direction all other data lines do. And the bypass capacitors are always in between the incomming VCC to the pin and the VCC pin on the IC itself, but never afterwards, as per illustration below:

If it is true that it is ok to place bypass capacitors in such a fashion, then it would be possible to combine that design with placing bypass capacitors as "bridges" over adjacent data pins of the ICs, would it not? As per illustration below?

Could anyone give me some insight as to whether this is ok, or if they have a better suggestion of how to place bypass capacitors?

Thanks!


texts:
A motor rated for 3S (11.1 V) has an internal resistance of 0.12 ohm. The maximum current is 22 A.

11.1 V / 0.12 ohm = 92.5 A

Doesn't this mean that by supplying a 11.1 V three phase current, the motor will burn up instantly? How does an electronic speed control (ESC) prevent the current from exceeding 22 A?


texts: I have attached the problem and my attempt with the solution. The official answer to the problem is option(B). Please guide me where I am going wrong in solving it.


texts: Are built-in ADC converters in MCUs as reliable and accurate as their standalone counterparts?

texts:
This question is inspired by this comment by KyranF:

  "built-in 24-bit ADCs" I wouldn't trust that as far as I could throw it.

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

As the title plainly states, is there any foundation for this comment and are built-in ADCs any less accurate than a dedicated chip, and if so why? What parameters on an ADC should be looked at for accuracy and precision?


texts:
I'm developing a driver for multiple USB speeds and according to the universal specification, I'm allowed to draw a greater amount of current from a USB 3.0 hub than the other versions.

Is there a way on Windows to determine the different USB speeds? I'm basically asking for a place to get started. Thanks in advance.


texts: Calculating cell resistance in dependence from cell temperature from CAN bus logs

texts:
I'm part of a formula student team. When we go testing we are logging the CAN bus data the car produces to further understand what the car is doing.

We log all the battery cell temperatures/voltages and the current going trough the cells. With this data I want to calculate the resistance as a function of the temperature. In the laboratory this task is easy since you have a constant current going through the cells. With the voltage drop over the cell you can easily calculate the resistance. Unfortunately this is not possible with the logs since the current is always changing.

Things I've tried:

Get all the voltages when no current is flowing. Connect this data. Then try to guess a resistance of the cells so the actual voltage and voltage with no current is lining up. This approach while giving decent results neglects the dynamic nature of the cells.

The "ideal" approach:

Creating a bode plot of the current as input and the voltage as output. Then fitting a model of a cell onto that plot. This model has a resistance parameter. Also other parameters like capacitance could be measured this way. Being a frequency analysis, this would show all the dynamic behavior of a cell. Doing this in 30s parts to the whole signal and assigning the parameters to the mean temperature of that period would get the temperature dependence.

Available tools:

Python(favored)
MATLAB R2018a
Any free program/language

Also any suggestions or insights would be great!

Here is the data in pickle format (Python): https://classic.hidrive.com/lnk/rZHA1ahy

Here is the data in MATLAB format: https://classic.hidrive.com/lnk/tdng1sOb (just rename it .mat)


texts: What's cheaper & faster for my lab, keep a stock of electronics components or order?

texts:
We are four electronic engineers working in a company, and we have a lab, I think we have a logistic issue with our components, this might be a basic study case:

We have few racks with resistors, capacitors, chips, transistors, diodes, connectors, LEDs, and so on.
We have projects all the time, and have plenty of boxes with unsorted components in low quantities, for each project.
We currently don't keep track of our stock.
When we have a need for components, we would just order or maybe take a look before order at Mouser, Digikey, Farnell etc...
BIG ISSUE ::: When we need to pass an order, it would take at least 1 week for administrative reasons.

We have arrived to the point where we need to know:

What is cheaper? Keep a big stock (keep track of it) or order  components we need (constantly)?

Update:
I will add that, we have recently bought several SMD resistor/capacitor kits, and this simplified our situation. If you have any other tips like this it would be great!


texts: How much installed capacity of wind or pv would be required to match the output of a 4GW nuclear power plant

texts:
I am trying to understand the challenge of decarbonising the power grid, and the equivalence between different generation technologies.

If a nuclear power plant has a capacity of 4GW and a capacity factor of 90%, how much installed capacity of wind turbines with a capacity factor of 40% would be required to match that output?

How about the same with solar pv with a capacity factor of 25%?

What area of land/sea would be required by that installed capacity of wind or pv to match that 4GW power output?

These are the numbers I get but I have been told they are ridiculously wrong.
One of the worlds largest offshore sites is the London Array - 630 MW 122 sq km (47 sq mile)
That works out to 194 sq km per GW installed capacity. (75 sq mile)
The London Array capacity factor 36.8%
So to produce 1GW average power you need to overbuild by a factor of nearly three, and would need about 200 sq miles.
A large nuclear power station puts out 4GW, so equivalent power to about 800 square miles of offshore turbines.


texts: Using multiple shunt amplifiers with a single shunt resistor

texts:
I have a 10mohm 1% resistor that I want to use to measure current. Since I need multiple ranges I want to use multiple amplifiers with different gains (INA212-Q1, INA213A-Q1, INA214-Q1) with the resistor and connect each output to a separate ADC pin on an MCU so that I can avoid any sort of analog switching on the shunt side which could distort readings or interfere with the load.

simulate this circuit – Schematic created using CircuitLab

My questions are:

Is it sane to put multiple amplifiers on a shunt like this? And if not, which alternate scheme should I be looking at instead?
How much will this affect the readings and the load?


texts: What is the purpose of masking the LFSR value in STM32's noise generation?

texts:
I read on section 14.3.8 of the STM32F4 reference manual that you can mask the LFSR output value partially or totally.

At first I thought that it was used to change the pseudo random pattern (representative polynomial function) but I'm not really sure anymore.

What's the real purpose of this mask?

I'm not very familiar with LFSR noise generation so I might have got everything wrong...


texts: What happens if an object has a negative electrical charge and it is touched to an object with a neutral charge?

texts:
I am a beginner in this subject and trying to understand the basics.
If I rub my feet on a carpet and pick up additional negative charge on my body and touch a neutrally charged object, say a piece of metal, will the excess electrons in my body not flow into this object because it is neutrally charged?


texts:
I am struck in the above problem. The things I was able to figure out are

It is a DC motor
Direction of effective flux [Armature flux + Main Field Flux] due to the brush shift

But I am still confused how can we draw voltage waveform out of this information. My workbook says the answer will be option A. Please help me with the problem


texts: Need help to design efficient zero crossing CURRENT detector : clamp diode solution

texts:
I try to design a replacement potter's wheel motor controller for an old potter wheel. I have solve my zero crossing voltage detector and TRIAC command.
Now I begin to understand the importance of the phase shift between current and voltage on inductive load like motor and I think I need to detect the real state of the triac.

In addition of zero crossing VOLTAGE detector, I think I need an isolated zero crossing CURRENT detector to be sure TRIAC is really off.

Inspired from this schematic, the idea is to put diode in series with the load, to use forward voltage as limiter for the optocoupler SFH6206-3 like the following schematic:

I select STTH20R04G-TR diode because they can handle more than 16 A

I use the forward voltage dropout of diodes (2 x 1.7V) minus SFH6206-3T diode forward voltage max (1.65V) to get the voltage accross R10 (1.75 V)
I want 1 mA to the optocoupler diode so I need (3.4-1.65)/0.001 = 1750 ohms max, I select R10 as 1600 ohms from E24 serie.

For the output of the optocoupler I use CTR value of 34%, so I probably get 0.34*0.001 = 340 µA through R10 when current flow to the load.
I want IZCD low level as low as possible (VIL of µC is 1V and VCESat is 0.4V) so I want 2.9V across R10, R10 must be at least (3.3-0.4)/0.000340 = 8529 ohms.
I select 10 kohms and get IZCD = 0.4 V when current flow to the load

When current not flow to the load, there is a current leakage of optocoupler (50 nA).
I got 10000*0.00000005=500µV across R10 is this case, IZCD~=3.3V when current stop to flow through the load.

I'm not confident with TRIAC leakage current through snubber and I think a forgot something...

Can you help me to take a look of my zero crossing CURRENT detector and tell me if it can theoretically work?
I'm not confident with the "as is" STTH20R04G-TR power dissipation do you think they are ok? Do I need heat-sink? (They are bit big, did you know smaller diode without the need of heat-sink?)
Is there an other (isolated and simple) way to detected current flowing and stop flowing through the load to be sure TRIAC is really OFF.
(I know TRIAC voltage is low as ~1.5V when TRIAC is ON but I don't know how to exploit this information?)

Thanks in advance for you help

EDIT 2019-11-03 (Thanks to Bruce Abbott)

I move the the current detector between the TRIAC and snubber and correct the optocoupler resistor value. (R10 can be 1/4 W).

  At 1mA the typical optocoupler LED voltage is ~1.025V, so assuming
  0.6V per diode the required value for R10 is ((0.6*2)-1.025)/1mA = 175Ω. At 3.4V the LED current will probably be around 10~15mA.

Using a standard diode like DSI30-08A, we can found the calculation values in the datasheets

Forward current versus voltage drop of DSI30-08A

Diode Forward Voltage (Typ.) vs. Forward Current of SFH6206-3

I think this first solution is not really optimized, it seem to loose a lot of power, I hope someone got a better architecture to detect current zero crossing.


texts: I have these foreign Japanese transistors, and was looking for their equivalent in the 2NXXXX series.  What would be a good replacement? This is the first time I have seen any of the transistors any other information needed that I put just comment and tell me.


texts:
Given a circuit like a buck-converter like the AOZ1284PI in a circuit such as this one:

Or push-pull converters such as this one:

If one was to design at the output a low-pass PI filter with a cutoff frequency of 10kHz for example (purely hypothetic), how would one proceed?

I don't see much information about the PI filter. Somewhat there is no real voltage Vo/Vi transfer function like a LCR filter, but instead there are design rules like using the line characteristic impedance \$Z_0\$ if I stand correct (like here).

I'm not even sure what to put as \$Z_0\$ because after all this would be on a PCB so the line impedance must be extremely low? Does it really even matter?

Except, with a SMPS IC it's next to impossible to determine the output resistance of the IC, or the equivalent load impedance \$Z_L\$ (imagine you design a PSU, there are tons of loads possible here, and nevertheless if you supply say a MCU you cannot really predict that load because it's variable).

So given all of this, how does one actually implement a PI filter to filter the ripple voltage, given your Q factor must be around 0.707 to avoid making an oscillator in the process? Given for example a max current of 100mA, fc=10kHz, \$Z_0\$=no idea (how would you determine it)?


texts: How to generate 2-FSK signal from the bit stream(symbols)?

texts:
I’m trying to generate a 2-FSK Signal, Let’s just consider the following,

Symbol Rate : 1 MS/s
Sample Rate : 10 MHz,
Frequency Deviation: 150 KHz & -150 KHz

And assume I’ve 100 symbols : {1,0,0,0…..0}

Now, I want to generate a FSK signal from the above parameters, along with a Gaussian filter. How do I start from here?

Edit:

I’m trying to implement this on C#, I found the following formula,

from the formula, f1 & f2 are the frequency deviations but I'm not sure about the t?

Thanks for your time..:)


texts: Capacitor charge - why a resistance is needed?

texts: I'm wondering why every example of a circuit capable of charging a capacitor has a resistor in it. Why is this resistor necessary?


texts: On the back of my house is the breaker box. It has an open 40AMP fuse (not connected to anything any more). There is also a 20AMP fuse connected to my shed. When the shed was originally built, it was only going to be used to hold junk and so a couple of incandescent light bulbs worked fine. Now I'd like to use the shed as a workshop. I'd like to be able to run a window AC unit (700w IIRC), several LED workshop lights (like the old fluorescent tubes but only LED instead), and some power tools, nothing crazy. Can I move switch the breakers in the breaker box so that I have the 40amps available to my workshop?


texts: Using a 12V lighted toggle switch with an Arduino

texts:
I would like to connect a 12V lighted toggle switch to an Arduino and be able to read its state (replacing the momentary button in this tutorial with this switch).  But the Arduino has only 5V power supply.  Can I connect the 12V switch to the 5V power supply?

Update:

There are just three contacts on this particular switch. The contacts are labeled source, ACC (presumably accessory) and ground. When you close the switch, it connects source to ACC and also connects source through the lamp to ground. There is just a single power source in the circuit.


texts: Is high current in a speaker the same as high voltage?

texts:
I'd like to build my own Amplifier, and because I know that the current creates the magnetic field, I don't understand, how amplifying the voltage makes it louder. I mean with high voltage doesn't automatically come high current. For example if an Amp can only deliver 100V at 1A (I don't know whether such an amp exists but ok) (the reason for that is the Load Resistance RL, right?) , then the Output Power is 100W.

Would that make the same sound on the same speaker in same Conditions, like if I put 100A with 1 V through it?

EDIT:

Ohh thank you guys for that many answers in that short time :_D

How could a class D amplifier amplify with ~90% Efficeny, if 4,5W is the Maximum amount, you can get out of a 12V PSU? (4,5W/0,9 = 5W -> 5W / 12V = 0,417 A) That would mean, the PSU has 0,417A of output current, and so, because the output current can be calculated, the current doesn't play a role... How could that be? Or is that the reason, why you wrote "Rough Calculations"?

In case, higher Impedance means the Voltage of the Power can be higher: If i want to build a Subwoofer with Amplifier out of a Car-subwoofer with 4Ω , is it a must, to have relatively low Voltage audio signal and relatively High current? Then, depending on Phil G's Explanation, i have to build an Amplifier with high Current Output? How to calculate the Current and Voltage I need to achieve the wanted Power of 200W through that 4Ω Subwoofer?

My plan is, to RC Low-pass filter the Pure Audio Signal, amplify it and put it out on my Subwoofer, any Ideas? Ty for Answers in advance!


texts:
I am trying to use TVS diode to protect Integrated Circuits from surge voltage introduced from exposed connectors.

TVS will be attached in following way.

I wonder what happens if too much of voltage of current is applied to the TVS diode and it "burns".

If it "burns" to open, the circuit will still function normally, only without protection.

However, if it "burns" to short, the circuit will lose it's functionability.


texts:
This diagram is from a PWM solar charge controller datasheet,

http://www.epsolarpv.com/en/uploads/news/201310/1382338419195066.pdf

I have 2 questions about it:

1-Why they used two MOSFET in series rather than one?

2-Can we simply increase the max. current of any PWM solar charger by replacing its MOSFETs by another with higher current or it need to more modifications?


texts: Opamp input bias current and current sources

texts:
I have a current source connected to a load and I want to measure the voltage at the output of the source, and therefore I would like to buffer this voltage.

In this configuration, I am under the impression that the opamp will always draw the same amount of current from the current source regardless of what current it is set to output. (Eg an opamp with a bias current of 1uA buffering the output of a current source producing 1000uA will result in 999uA going to the load. If the current source produces 2000uA, 1999uA goes to the load.)

If this is the case, it seems like I don't need to necessarily seek out an opamp with a low bias current, but I could simply offset the current source by the bias current to ensure that my load gets the desired current.

Is this thought process correct? Or would using a very low bias current opamp still be of significant benefit here?


texts: What is oscilloscope trigger "sensitivity"?

texts:
I'm learning more about digital oscilloscopes (previously have only worked on analog), and encountered a setting for trigger sensitivity, expressed as a value like 0.30 div.

Tektronix gives this description:

  The oscilloscope will trigger on a signal of 0.35 divisions amplitude p-p in the range of frequencies from DC to 50 MHz. As the frequency goes beyond 50 MHz, the signal must be larger (higher in amplitude) to trigger the instrument. At 3 GHz, the signal must be at least 1.5 divisions in amplitude. Trigger sensitivity is specified with a sine wave input.

I'm confused because I thought the trigger level (the horizontal bar which selects the desired amplitude for the trigger) was a yes or no type of event. Either the waveform reaches the level or it doesn't.

The manual for the DSO I am using (a BK 2542B) doesn't explain this setting well at all: "Set the trigger sensitivity by turning the entry knob."

I'm suspicious it applies only to trigger types such as pulse and video, but sensitivity appears in the triggering menu regardless of type.


texts:
I create electric scales that will work with small scales.

Microcontroller: Atmega328
Display: SSD1306
Load cell + HX711

I want to charge this device using USB. To do this, I will use TP4056 (allows you to charge a Li-ion battery and use this potential).

Q: Is battery enough to power the Atmega328, display, HX711.

The output will be 5 volts is this enough?


texts:
So I am trying to build a standalone circuit using the Atmega 328p. After uploading the code using Atmel Studio and AVRDude I get no response from the circuit; however, when I take the Atmega and put it on an Arduino board I can verify that the code uploaded works. Can anyone shed light on what I may be doing wrong?

Here is what I have so far:

I am using a 16Mhz crystal with 2 22pF capacitors
An LED which verifies that Atmega is powered on
I am using a USBAsp clone programmer

I took an image of the circuit I have below.


texts: Reflect IR beam off reflector instead of emitting straight to TSOP receiver

texts:
I have a working set-up to detect beam breaks using an IR LED, modulated at 36kHz, and a TSOP receiver connected to a comparator. It outputs the count via Arduino. The range is about the width of a door, say two meters maximum.

The transmitter and receiver are on a separate breadboards. This has its disadvantages, such as two sets of batteries.

Is there a way to reflect the IR LED off a reflector and having the TSOP receiver on the same breadboard as the LED? Perhaps behind it? The German term 'lichtschranke' seems to be what I vaguely have in mind, but I don't speak German and can't find it in English.

Does anyone have suggestions on how to modify my current set-up or can anyone point me to some schematics?

I am guessing something will need to be done in order to maintain a straight or angled beam and not have it reflected back all over the place.

How can I mount an IR emitter and receiver on the same circuit board to detect a reflection instead of a straight beam?


texts:
According to this site in a buck converter with voltage mode control the duty cycle is set directly by comparing a voltage ramp to an error voltage. I agree with that. But this is where my headache starts:

If Vo < Vref,  then Ierr is positive               - increase V(10) and the PWM duty cycle.
If Vo > Vref,  then Ierr is negative              - decrease V(10) and the PWM duty cycle.
If Vo ~ Vref,  then Ierr is close to zero       - maintain V(10) and the PWM duty cycle

where Vo is the output voltage and Vref is the reference voltage. Well, the first two lines are ok for me, but i can't imagine how the duty cycle is maintained, when Vo ~ Vref.
My assumption here is, that when Vo ~ Vref holds, then the duty cycle should be set to 50% and not maintained. Or am i missing something here?
Regards
Macs


texts: Explanation of the Node-Voltage Method equation in specific circuit

texts:
I'm looking at this circuit in my textbook:

There are also equations for this circuit:
\$ u_n(t) = R1\cdot i_1(t) + L_1\frac{di_1(t)}{dt}-M\frac{di_2(t)}{dt} \$
\$u_C(t) = -R_2\ln(i_2(t)+1)-L_2\frac{di_2(t)}{dt}+M\frac{di_1(t)}{dt}\$
I totaly agree with the first equation. But I don't understand, why the second equation looks like this. I would wrote it as:  \$u_C(t) = R_2\ln(i_2(t)+1)+L_2\frac{di_2(t)}{dt}-M\frac{di_1(t)}{dt}\$
I see the current \$i_2\$ comming in the opposite direction than voltage \$u_C\$ same as the current \$i_1\$ is comming in the opposite direction than voltage \$u_n\$. So what is the differnce? Is it something about the \$u_n\$ being the source and \$u_C\$ consumed voltage? Could anybody explain?


texts:
I have an electric lock that needs 12v to stay in a lock position. It opens on 0v.

I was thinking about controlling this with a MOSFET (IRFZ44N).

Currently I have the following setup:

The 12v power supply connected to the source pin.
The drain pin is connected to the power wire of the lock.
The gate wire is not connected (yet)

With this setup the lock starts in a lock position. So it gets 12v.

Can I control the gate pin by simply connecting it to an Arduino output pin? Can I control this MOSFET with an Arduino board?

If so, is it just a matter of setting the output pin to LOW and HIGH to control Gate?

I'm trying to follow this schematic (not mine, just trying to follow it):


texts: Why is inductor completely canceling out current?

texts:
I used this calculator to determine that my hand-turned inductor has an inductance of approx. .5 uH.

simulate this circuit – Schematic created using CircuitLab

When I measure this circuit on a multi-meter every node on the circuit is measured in mV. How is this possible? When I use Ohm's Law to get the inductor's resistance it is measured it is measured in thousandths of an ohm.

Why aren't I getting around 9v with a realistic voltage level?


texts:
I try to make a little project for school.I used the following schema to create an audio amplifier.

For the circuit I used:

C1:104j63 capacitor (1uF)

C2:103j (0,1uF)

My problem is that the sound is lower than direct input.

I changed both capacitors with a 104 and the sound was same as the input but more distorsioned.

PS:The transistor is connected correctly.


texts: What if the primary coil of a transformer was connected without the iron core and the secondary coil?

texts:
I'm trying to create an electromagnet from a microwave oven transformer. The secondary coil will be removed, and the top of the transformer (The I in the E-I transformers) will be sawed off (to increase field strength).

My DC power supplies can only supply low currents (12 V @ 5 A, 20 V @ 2 A) since it's DC, so I thought that AC current might be better. I'm not that familiar with using AC. The problem right now is that I'm unsure whether removing the secondary coil and cutting the top off will cause a short circuit issue.

This is because I had read somewhere that the impedence comes from trying to change the magnetic field of the iron core (in between the cycles). With part of the core removed, would that cause any problems?

To clarify further: The only thing keeping the primary coil from short circuiting is the flactuating magnetic field (trying to change the magnetic field of the iron core). So with part of the core removed (only the I part of EI), would that cause any issues?

Thank you for your time. Any related articles/resources would also be helpful.

Note: I'm using 240 VAC @ 50Hz.


texts: 3 bit synchronous counter design d flip flop

texts:
Any idea how I would go about designing a 3 bit  synchronous counter in regards to having the following states

111->001->110->101->100->000->010->111

I drew up a present state and next state table etc... not really sure where to go from here, I have designed in logism a start schematic with a CLK, CLR and PRE, with 3 D type Flip flops as these are the ones I am required to use, but I am unsure where to go from here.


texts:
This is just a concept I was thinking about.
I have an arduino project with some dc motors that needs to run outdoors for a long time. The DC motors themselves do not need to run all the time, usually a 2-3 minute burst and at most for 30 mins at a time. They are 12v motors, drawing 0.4A at peak. I expect the overall circuit to draw around 2A during load.

I was looking at these solar battery packs, meant for charging phones with 5v output (has 3000mAh battery). I was wondering if I use a DC/DC booster and boost it to 12v to drive the motors, is it going to work well? I expect the battery will just drain faster, but since the motors are not used all the time, the solar panels can top up the battery when the system is resting for rest of the day.

For reference:
Solar batteypack: http://www.amazon.com/Opteka-BP-SC4000-Powered-Capacity-4000mAh/dp/B005ZSVZRY/ref=sr_1_6?ie=UTF8&qid=1369413420&sr=8-6&keywords=solar+battery

DC/DC step up regulator: http://www.robotshop.com/ca/productinfo.aspx?pc=RB-Dfr-121&lang=en-US


texts: Noise everywhere on solderless breadboard, could the DC-DC converter be the source?

texts:
I am using a solderless bread to prototype an analog sense -> 8 bit digital circuit.

It's messy
Has Hi gain sensing opamps
sensitive POTS

I have 20mV of noise everywhere, even when I am connecting GND to GND at a different locations... All of my ICs have decoupling caps. Putting more caps on the rails has no noticeable effect.

I assumed this is just from breadboards being terrible.

My question is could the DC-DC converter be the source of this noise?  If so I need to have a linear regulator power the analog electronics.


texts:
I bought a car that had a transmission swap, transmission was a bit lazy so i had it scanned. The transmission ecu is looking for a physical Wide Open Throttle(wot)switch that is grounded when the pedal is depressed. What i want to do instead of using a physical switch, is to use a transistor that is grounded when the base signal is above 4 volts, this 4 volts will be taken from a Throttle Position Sensor(TPS) that ranges from about .3v-4.8v. I am not certain but i think the transmission's ecu wot port that will be grounded might have a 5 volt reference with average amp draw of about 1ma - 3ma, the tps signal might be about 1ma-3ma also.

What resistor would i use for R1 and what transistor model would i need? Would i even need a resistor being that the tps in essence is a resistor? Thanks in advance.


texts: DC Bus for Solar Charge Controller Battery

texts:
I am just learning the set up for a back up power. I am just wondering whether the DC output from the charge controller or the battery can be used for multiple loads.

For example, I want to power my modem which has a rating of 0.5A, 12V and my laptop which is 19V, 3.4A. How am I suppose to get the power from the battery if there is only 1 line coming from the battery or the controller. I am also planning to make an LED panel light.

I am just confused on how to go about this. I hope you could help me with diagram or if ever I will be needing a circuit for a bus.


texts:
I have tried to find answers to this many times, and the only solution I have been able to find is having two 555 Timers (or a 556) one in astable, and one in monostable.

I could easily do this with an arduino or something, but thought using CMOS and logic IC would be more fun and challenging.

But in short I have a project which will be using two 4029 counters to keep track of scores (and a few other features, but irrelevant to this question), and I have three buttons, one to increase the counter by one, another button to increase by two, and another to increase by three.

I am having trouble finding a simple circuit that can pulse the 4029 two or three times, I know I could just press the one button two or three times, but with how this will be used separate buttons are preferred.

Not sure what other information I can supply that might help explain better.


texts: I want to save up in buying a sense resistor and just use the PCB tracks. I need to sense up to 2.5A and I wanted to design the trace so it has a 0.1 ohm resistance. Is this a good approach? Also, can anybody share the calculations about how to determine the track length and width assuming a 1 Oz copper thickness?


texts:
I use PIC16F1825 to communicate via UART (async) with external device. Running on batteries I have to spend as little power as possible.

Since my external device may transmit no data for minutes I though about putting the PIC microcontroller into SLEEP mode while waiting for data.

Unfortunately it's not simple, because asynchronous UART requires main oscillator (PIC manual). Implementing UART manually may solve the problem, if PIC would be able to recover from SLEEP quick. My PIC16F1825 device requires 1024 x Tosc to start working after SLEEP. It's way to slow :(

UART: 115200N8

My question is: How can I save considerable amount of power during the time between transmissions?

PS
I can move to some other microcontroller within the same price region and packaging size (4mm x 4mm).


texts: How to remove GPIO ribbon from raspberry pi

texts:
This is basically it. I got my new raspberry pi and I got a GPIO ribbon to connect it from the raspberry's GPIO's to a breadboard. Now I am trying to remove the ribbon from the raspberry by just pulling upwards, but despite the great amount of force I've used, it does not come out.

How do I get the ribbon out of the pins?

Thank you!


texts: USA Voltage versus Australian Voltage Question

texts:
I am a complete novice to electronics and I have a very basic question - this being my 1st question!
I am in Australia and I am ordering electrical components to start my 1st build by following instructions written for the USA.
The suggested piece of equipment is this Crydom 40-Amp Relay.
The voltage in Australia is 240 volts (now moving to 230 volts to match Europe) while the USA is 110 volts.
Should I be ordering a relay that is suited for Australia - such as this 240-volt Crydom 40-Amp Relay?


texts: I need help rewiring a pre-1950s Mimms lowboy fan. Any advice on rating the cap (3speed coil) and 4-pos 3-way rotary switch

texts:
The cord was brittle and crumbled, so I cut it off.  Internal wiring is cloth covered solid copper. 3-speed coil/cap.  The 4-pos/3-speed switch rotates freely/well, but not sure if it or the coil is safe to use. Thus, I want to rewire it and use the antique fan. Great conversation piece.
Motor =  F.A. Smith (Pilot), 115V, 60cycle, 1.52amp (? 0.52amp? hard to read on plate)

What type coil or cap can I use or need? #on coil is ~ "192201 31".  No brand name or ID on it.  3 wires labeled Lo, Med, Hi.  All 3 wires lead to switch terminals.
Any suggestion on mfd /uf ratings I should look for on new coil or cap.
Can I replace old coil with new style capacitor or must I use an old style coil?  This looks to have "leaked" small drops of oil or tar? from between some of the plates in coil on 3 or 4 sides.  Safe to still use??
Old coil only had 3 wires (L,M,H) that fed to switch.  What type cap do I get and how to connect to switch?   3-wire cap?  What size mfd ratings?
Source for 4-pos/3-way switch?? Would something like HQRP 3sp1t switch work?  I want to retain the old switch face and knob of original rotary switch.
How to wire new cord? 1 wire to motor and other to Load on new switch. But which wire from outlet is load or neutral? Original plug / wire was not polarized or grounded. Does it matter if new wire from outlet is polarized or not, in this case?  I don't want to short it out.  Which wire (of the 2) goes to motor and to switch or does it matter if reversed?
How do I tell if motor is still good before I start rewire process? It has an oiling port too.

Lots of questions! Maybe too many at 1 time? I don't want to end up with a meltdown of this beautiful-to-me old fan.  :-)
Thanks for any guidance!
Kind regards and thanks in advance.


texts: how does better isolation between gate and channel in a mosfet, result in a higher input impedance?

texts: I wanted to know what are the factors that affect the input impedance of a device, majorly in a MOSFET, how does better isolation between the gate (resulting in less leakage current) result in a higher input impedance?


texts:
I recently came across a quite large power plug for a three phase industrial motor. Like the following:

After loking it up on wikipedia and also other sources I found that it's meant to signal the load.

This smaller pin in the center of the connector is shorter than the others, designed to 'make' after all the other pins when connecting a plug and socket, and to 'break' first when disconnecting. It is used to switch off the load. This is useful as disconnecting under load will cause arcing which may cause damage to both the plug and socket, and risk injury to the user.

What I haven't found is information about the signal that is going through this pin.
So my questions are:

What voltage should be on this pin?
Which is the max current that it's supposed to handle?
Is it AC or DC? I guess AC.

If AC what frequency does it have? I guess the same as the phases.
If AC what phase offset does it have?


texts: What is a terminal plane in high frequency circuits?

texts:
The term "terminal planes" come up very frequently in books on microwave circuits. What exactly does the term mean?

The closest answer I have got is

  A terminal plane, or reference plane, is the  equivalent of a terminal
  pair in a low-frequency network
  -Foundations of microwave engineering, Robert E Collins

But I don't understand what a "plane" is in this sense, and I don't understand why we couldn't just use the term terminal port?


texts:
I am using Quartus II to compile my Verilog design, and I'm working to properly constrain my signals.

I know how to constrain clocks, for example:

create_clock -name clk_i -period "157 MHz" [get_ports clk_i]

I also know how to constrain input signals relative to a clock, for example:

set_input_delay -clock clk_i 0 [get_ports data_i*]

However, I don't know how the (asynchronous) reset line should be constrained. How are reset lines constrained?


texts: Very low power: Most power-efficient way of storing charge for hours

texts:
I'm researching the feasibility of doing an art project that involves soaking up ambient RF power in a city (energy harvesting) and then playing a 1 second sound clip through a speaker as soon as there is enough stored energy to do so. There will be no other source of energy -- not solar, not anything, just ambient RF harvesting.

It looks like RF harvesting might give me about 10 microwatts.  And my 1 second sound clip, played at human speaking volume with an efficient amplifier should need about 10 microwatt-hours. So I would need to charge some kind of battery or capacitor for say 1-5 hours at 10 microwatts, and then discharge it in 1 second and repeat.

Given that, what might be some options for storage devices/circuits? Which are the most efficient and most inefficient setups for the parameters stated? In other words, is there any charge storage tech that could achieve the above behavior?


texts:
According to ST AN2867 Oscillator design guide for STM32, the oscillator circuit requires a Rext resistor

There are minimal boards with stm32f030f4p6 on ebay, aliexpress...
It looks that rext is missing on the schematics. It only have a crystal and 2 capacitors
Do you think the board can run on HSE anyway ?

Here is the schematics
http://www.uctronics.com/download/U3808-1.jpg

Thanks


texts: Why do I get high DC current in grid tied inverter output?

texts:
Edit: Added gating signal waveforms. Changed some of the graphs, I accidentally put a test circuit waveforms the first time. Current is not that high but offset is there and current is high for a lower inductance.

I am new to using PLECS and power electronics in general. I am trying to simulate a grid-tied power inverter where I am using a 300V dc power source, inverting it to 60Hz AC, and then connecting to a 60Hz AC grid (120 Vrms).

It successfully gives me the voltage I want. But I am getting a 0.567A dc current offset. This offset and the total current gets very high if I reduce the inductor size. Questions:

Why is there a DC current offset, even across the transformer?
How to reduce this offset to zero?
The power output is awfully high. How to reduce it or control the current?

The circuit information is as follows:

I am switching S4 and S3 with a 60Hz (in sync with grid) pulse train with 0.5 duty cycle. S1 and S2 are switched at 60 kHz with sinusoidal pwm.
Duty cycle = (Vc_peak/Vdc)* sin(2*pi*60*t).  S5 and S6 are inactive.

.

When I measure the grid (final output, right side) voltage and current , I get this. Notice that the current wave is not biased at zero!

.

This graph includes the measurements at the primary side of the transformer, i.e. inverter output. Vc is the inverter output voltage, showing average for clarity. Vs is the sine output voltage after the inductor. Is is the current through the inductor. Igrid is inverted in this graph to match the signs.

.

Switching waveforms:

Duty cycle of S1. The graph shown is a graph (sine at 60Hz) of duty cycle, actual switching is at rate 60kHz :
Duty cycle of S2 = (1 -Duty cycle of S1).  S2 = not S1.

.

Signal waveform for S4:

T = 1/60. 50% duty cycle.  S3 = not S4.


texts: Clearance between planes in a split plane layer?

texts:
When creating a split-plane layer, my cad package (SW PCB, based on Altium) uses simple primitives to draw the border between the plane regions.

It seems to take those primitive dimensions and transfer them directly to the gerbers.  I expected it would take DRC rules into account, using the primitive centerlines as the midpoint between the planes and use the DRC to determine the minimum distance between the planes.

1)  Can anyone advise what the minimum distance should be between planes on an internal split plane layer?  My designs are usually 5V mixed signal circuits.

2)  Can anyone advise if the expected behavior I described above is correct?  Even if the CAD package doesn't automatically space the planes apart, I would at least expect a DRC warning.

Thank you.


texts: Getting different results for memory reads over STM Programmer GUI vs CLI

texts:
I am working on a project using the STM32WB55xx series. I'm trying to read the Device Information Table (AN5185 Section 6.6.1, pg 17) using a bash script and the STM32 Programmer CLI.
According to the documentation (AN5185 Section 1.2 page 3) I should be reading the IPCCDBA option byte to get the device info table address at the start of SRAM2a. The IPCCDBA value is 0x0, so the device info table address should be located at address 0x20030000. If I try to use the CLI to read at address 0x20030000, I get all zeroes in response.
If I read the same address using the STM32 Programmer GUI, at first I get the same thing:

However, if I switch to the CPU tab in the GUI and hit 'Run' first, I can check address 0x20030000 and I find a value of 20030890:

Then, I can read address 0x20030890, and I find the device info table, including the 'table valid' bytes 0xA94656B9:

Success! It seems that hitting the Run button makes all the difference for the GUI.
So now going back to the CLI, it appears that the analogous command for the Run button in the GUI is the '-run' flag in the CLI. Yet, even when I add in the '-run' flag to my command, I still do not get the 0x20030890 address showing up at 0x20030000. Only zeroes.
I suspect that there may be some syntax error or option I'm missing from my CLI command structure. What do I need to do to get the CLI to return the same data as the GUI?
Script body:
application_path="/c/Program Files/STMicroelectronics/STM32Cube/STM32CubeProgrammer/bin/STM32_Programmer_CLI.exe"

"$application_path" -c port=SWD -r32 0x20030000 42
# ^^This reads all zeroes...
read -p "Press enter to continue"

"$application_path" -c port=SWD -run -r32 0x20030000 42
# ^^This still reads all zeroes...
read -p "Press enter to continue"

Script output:
$ "$application_path" -c port=SWD -run -r32 0x20030000 42
  -------------------------------------------------------------------
                   STM32CubeProgrammer v2.5.0
  -------------------------------------------------------------------

ST-LINK SN  : 066FFF36...(redacted)
ST-LINK FW  : V2J37M26
Board       : P-NUCLEO-WB55
Voltage     : 3.24V
SWD freq    : 4000 KHz
Connect mode: Normal
Reset mode  : Software reset
Device ID   : 0x495
Revision ID : Rev Y
Device name : STM32WBxx
Flash size  : 1 MBytes
Device type : MCU
Device CPU  : Cortex-M0+/M4

Core run

Reading 32-bit memory content
  Size          : 44 Bytes
  Address:      : 0x20030000

0x20030000 : 00000000 00000000 00000000 00000000
0x20030010 : 00000000 00000000 00000000 00000000
0x20030020 : 00000000 00000000 00000000


texts: How can we calculate the transfer function from this filter?

texts:
I'm trying to calculate the transfer function of this high pass filter :

So basically I'm trying to find how I can find \$V_{\text{out}}\$.

Due to the amplifier we know that $$V_{in} = V_{\text{out}}$$
I know how to calculate \$V_{\text{in}}\$ but I can't seem to find \$V_{\text{out}}\$ because I am supposed to find this transfer function (since it is a Butterworth high pass filter):

$$|H_{ph}(j \omega)| = \frac{1}{\sqrt{1+ \left(\frac{\omega_c}{\omega}\right)^{2n}}} = \frac{\left(\frac{\omega}{\omega_c}\right)^{n}}{\sqrt{1+ \left(\frac{\omega}{\omega_c}\right)^{2n}}}$$

here \$n=1\$ because it's a first order filter

So I was wondering if any of you could help me and find this transfer function knowing that:

$$\underline{H}(j\omega) = \frac{\underline{V}_{\text{out}}}{\underline{V}_{\text{in}}}$$


texts: What is causing this long tail in the transient reponse?

texts:
I have a fifth order transfer function for which I designed a controller using pole-zero cancellation technique on a root locus. I am targeting \$<5%\$ overshoot and \$<2s\$ settling time. Currently, the overshoot criteria are satisfied.
Note I know that exact p-z cancellation is nearly impossible in real life.
The controller and the original 5th order transfer function are shown in Simulink below

which give a response with a long tail in the transient response, and thus, a very long settling time.

As per Chu's comment here,

Placing zeros close to poles in an attempt to 'cancel' is not too
clever. It's usually impossible to plonk a zero directly on top of a
pole and expect both poles and zero to stay put. The result is a
'dipole' (a pole and zero in close proximity) that gives rise to a
long-tail in the transient response.

and HermitianCrustacean's comment,

The 4th order controller you've chosen is difficult to numerically
model ...

What would be the root cause of this unacceptably long settling time, inexact p-z cancellation (the controller which is difficult to numerically model), or both? Any suggestions on how to improve the response would also be greatly appreciated.

Poles of 5th order system
   Poles =

   1.0e+02 *

  -9.9990 + 0.0000i
  -0.0004 + 0.0344i
  -0.0004 - 0.0344i
  -0.0002 + 0.0058i
  -0.0002 - 0.0058i

Zeros placed to cancel poles

4th order controller

I would be happy to provide further information if needed.


texts: Is airbath + air gun reflow appropriate for low-volume commercial production?

texts:
I understand there are a number of ways of reflowing individual SMT boards. I've seen small temperature profile ovens, hotplates, skillets, airbaths, and hot air guns used. I'm trying to determine which method is most appropriate for low-volume (<100 per year) commercial production of SMT PCBs.

I've observed something being done by another company, though at smaller volumes. Their reflow method was to preheat the board with an air bath, then spot-heat the board with an air gun to complete the reflow. They claimed a long and effectively problem-free history with this method.

Is this a viable method of SMT reflow for the volumes I'm talking about? Are there particular flaws or problems to watch out for?


texts:
I have just bought 3 linear hall effect sensrs of type SS495A. However, when I hook them up to my Arduino Uno's analog input, I get some really weird results.

I use a 5V power supply, and my output is 0.8V - always. It does not respond at all when I hold a magnet nearby.

According to the data sheet, the null output should be 2.5V, and it's sensitivity is 3.125 mV/G.

I have checked both the supply voltage and the output voltage with a multimeter, so I dont think there is anything wrong with my Arduino setup, and I have checked with 3 different sensors. I am really confused. Does anyone have a clue as to whats going on?

I bougth them from elfaelektronikk.no, Norways biggest suppier of electronics. They were brand new, and they were shipped in ESD protective bags so it would suprise med if all of them are fried.

I did not use any of the digital pins on the Arduino. I just connected to the 5V power pin, to the ground pin, and to the analog input (A0). I measured the voltage across V+ and Gnd pin on the sensor with a DMM, it was 5V. And I measured between GND and the output pin, which was 0.8V. This is the same result as I get from the analogRead.


texts:
I'm looking for a wireless, relatively small (think a quarter dollar size) temperature sensor capable of withstanding and measuring temperatures up to 600 °C (1100 °F). It is going to be located inside a metal mold, and I don't need to receive the data in real time.

Could anybody point me in the right direction?


texts:
Meaning of the symbol
What's the meaning of this symbol?


texts: How to achieve very accurate/fine rotation with motor

texts:
I am running an experiment where I need to rotate a lightweight dial (<5 grams, so very low torque requirement, and fairly slowly), but need to do very accurate, fine steps of 0.03 degrees.

Something like this (shown as direct-drive here, but I'm open to other options as described further below):

Which of the following motor setups/approaches would be most likely to succeed for my goal?

A typical stepper motor (say with 1.8 degree steps) and use 128-microstepping perhaps? However, this article states microstepping will achieve only resolution but not accuracy.
A stepper with planetary gearbox (51:1 ratio) like this example, or would this suffer from too much backlash?
A brushless DC motor along with a magnetic rotary encoder like AS5048 (14-bit resolution), and write my own PID loop to achieve the desired position?
A stepper combined with a magnetic rotary encoder to keep track of true orientation and consequently use this as feedback to correct against backlash in geared case (approach #2), or against missed steps in microstepping case (approach #1)?
Or some other approach?

Note: I have read there exist industrial-grade servos which can comfortably achieve the 0.03 degrees goal but these are way out of my budget, so I was hoping for a less expensive solution at the cost of tweaking and learning.


texts: How to treat the DC in calculate the time constant in RCL circuit having DC voltage source?

texts:
I want to ask that how to get the time constant for simple RCL circuit in order to get the natural response later, Here is the sample circuit. Assume that S is close at t=0 and the circuit is open for a long time

simulate this circuit – Schematic created using CircuitLab

when S close, in order to calculate the time constant \$\tau\$ in this case, I omit the source \$V_S\$ but then I don't know how the circuit which will be used to calculate \$\tau\$ look like. I thought \$V_S\$ will act like sort circuit so it'll look like this

simulate this circuit

but my lecturer said it actually looked like this, which doesn't have \$R_1\$

simulate this circuit

So what is the rule when omitting the source in case of: voltage source and voltage source. What if the switch is in series but not parallel?


texts:
I discovered an "funny" thing today.

I had used a GW instek probe GTP-150B-4 150Mhz in 10x mode and documented the result.

Today I noticed in the testing department that what I've measured doesn't correspond entirely to what they see. The pic below is what I got with the GW-probe, where the red lines is what the peaks are with the probe they use, which is a Tektronic P3010 100MHz 10X.

I tested the exact same probe on my own scope which is the same model and I got the same result. Firstly I thought it might would have something to do with the input capacitance, but according to the datasheets they have the same nominal input capacitance.

Before I tested I also ran the probe against the scope's calibration signal.

Any more ideas what this may depend on?

Additional:

In the pic below the same settings is used, just different probes.
As can be seen the high frequency spikes is a lot higher with the the tek-P3010 probe. I've yet not found an logical explanation.

With GW-probe 150 MHz 10x

With Tek-P3010 100 MHz 10x


texts: How to prepare observation table and plot frequency response of Butterworth Sallen-Key High Pass Filter

texts:
My assignment:

Design and simulate a Butterworth Sallen-Key High Pass Filter with the, fc = 10 kHz.
Prepare the observation table and plot the frequency response.

My answer so far:

I want know how to prepare the observation table and plot the frequency response.


texts: How to minimise trace fracturing in PCB design - multiple thin traces or one thick?

texts:
Designing a board with strict and inconvienient requirements.  Currently the boards are breaking frequently - the aim is simply to reduce this frequency as much as possible..  The board is a 100mm square but only supported with standoffs in each corner.

On the board are 20 throughhole 4 pin sensors.  Effectively they are analogous to DIP switches.

The PCB experiences a lot of vibration as well as intermittent force (perhaps up to 100N point load) randomly, suddenly applied on a random sensor.  Board is FR4 1.6mm.  The environment is also humid and moderately corrosive.

I would love to redesign/support the board etc etc to be supported better, not loaded heavily, with a backing plate etc - but this is not an option.

Unsurprisingly, the board traces breaks frequently under this flexing.  This generally causes unreliable performance.  Electronically the board is simple slow digital signals so noise etc is not a concern.

I'm unsure as to how best to prevent/mitigate the traces breaking.  I could either route multiple narrow traces for the same signal, thus my thinking being that stress is more likely to break one and the crack not propagate through to the others, or one wide trace.

I'm also thinking curved traces might be worth a thought and I'm interested in how best to connect the trace to throughhole connection to minimise risk of fracture.   Also interested in if using extensive ground planes may help and if the most critical traces should be routed on top or bottom of PCB - so that they are either predominantly in compression (top) or tension (bottom).  I have read around flexible PCB design but not got much conclusive information and am unsure if a rigid PCB that flexes is a significantly different case.

Thanks


texts:
I have simulated radar cross-section (RCS) data of a small drone using CADFEKO. I'm using MATLAB to do the data analysis part. I have tried the histograms, heatmaps, error bars comparisons but still cannot find a way to model the data.

The task is to do the statistical modeling of the RCS data. In other words, how can the simulated data represent the drone? A model that takes the data as input and tell if it is a drone or not?

Thank you,
Best regards


texts: Explanation of filter for op amp controlled MOSFET current sink

texts:
I have designed this circuit and someone suggested R and C to enhance the functionality of the circuit.
The circuit is basically a current controlled device. Depending on the voltage set by the potentiometer, the current varied through the circuit.
However, what is the aim of the R and  C?
How could they be calculated?
Could you please explain to me in certain detail its functionality and advantages?


texts: How to combine two chip enable(/CE) signals into one with discrete components?

texts:
My VIC-20 has a few bank select lines that are used for enabling ROM chips on the cartridge port.  When one of them goes low, it means that a certain 8KB region of the address space has been accessed.

Usually you can hook these up directly to the chip enable (/CE) pin of a ROM chip to essentially place that 8KB ROM into a certain slot in memory.

However, I have a 16KB ROM with only one /CE pin which means that I need to combine two bank select lines.  I know I can do this with a single AND gate (since the logic is inverted), but it seems like a waste to use a quad-AND or NAND chip if there was a simpler solution.

Note, only one of the bank select lines ever goes low at a time.  So the truth table would be kind of like:

A|B|O
-----
1|1|1
0|1|0
1|0|0
0|0|Never happens

Is there an elegant way to do this with discrete components?


texts: How best to split a stereo audio source (LR) to two stereo amps (LL+RR)?

texts: Suppose one has a stereo audio source with a single 3.5mm stereo output jack, and one wants to split the left and right channels so that each is produced on one of two powered (i.e. self-amplified) stereo speakers, each of which has a single 3.5mm stereo input jack — the intention being for each of the two stereo speakers to play its assigned mono channel on both of its own output channels, as if the input were balanced mono. Symbolically, this might be represented as {LR}→{LL+RR}. What would be the most straightforward way of accomplishing this?


texts: Logic to pull signal low on power loss until signals next rising edge

texts:
I have the circuit below using the MCP23018 I/O controller which is always powered. The issue I'm having is that the signal USBC_RST_N controls the reset line of a PCIE-USB IC which has the ability to lose power momentarily. When the power is lost to this IC I need the USBC_RST_N signal to be pulled low until the I/O controller has the time to release the signal and pull it high again.
If the USBC_RST_N isn't pulled low before power to the PCIE-USB IC is restored then the device will not function properly and trigger a fault.
This has to be backwards compatible so I have to find a hardware solution to handle this scenario. I was thinking some type of latch circuitry would do the job but I can't seem to put something together that will work as needed. I'm hoping another set of eyes will help me see what I'm missing.


texts: My search for the SPR4 lands me here but couldn't find a definitive answer. I'm leaning towards SP but that is pointing me to BSS84. The designation on the board is "Uxx" while others are 'Qxx". Thank you


texts:
I'm working on a PCB. As ECAD software I am using KiCAD. All ICs will get two decoupling capacitor. One 100n ceramic and a 10uF electrolytic.

For now I place them like shown in the picture at each OP Amp or IC.

My questions starts now:
Since all capacitors share the same net, how can I make sure that the reference designator in the schematic later mach up with the physically placed capacitor in the layout. Is there any other way then looking them up in the schematic and then search for the right capacitor in the layout?
Or is best practice to place them and later rename all components with this external tool for Kicad. LINK


texts:
I am sort of a beginner at electrical engineering, could someone help me figure out how I can power an LED strip with batteries?

The led strips that I am looking at using are these. They takes 12Volts input, and use about 3Amps. I want to know how I can power these lights at full capacity with batteries / which batteries should I choose?

I'm thinking maybe one of these and a boost converter to go along with it? Or is there a cheaper way? I just want to make this LED strip portable with a battery pack so I don't have to plug it into the wall. Also, how long will these batteries usually last if the strip uses about 3 Amps?

Sorry if these questions seem basic, but any help is appreciated!


texts: How can I calculate the volt-second balance of a boost converter with 2 outputs?

texts:
Say I have a boost converter, but it has two outputs and three states.
On interval it charges up the inductor, the next interval it charges one output, and the next interval it charges the other output.

In below schematic I connected the load between the two channels, but normally the output of a boost converter does not depend on the load. Alternatively consider two loads to ground, or no load at all.

simulate this circuit – Schematic created using CircuitLab

Looking at the Wikipedia section about boost converter operation, they derive the usual 1/(1-D) from the fact that during steady-state the total variation of the inductor current is zero.

Let D be the duty cycle from the inductor to ground and k(1-D) and (1-k)(1-D) the duty cycles to the two outputs.

\begin{align}
\Delta I_{L,on}=&\frac{1}{L}\int_0^{DT} V_{in} d\tau\\
\Delta I_{L,on}=&\frac{DT}{L}V_{in}\\
\Delta I_{L,cross}=&\frac{1}{L}\int_{DT}^{(D+k(1-D))T} V_{in} - V_{out,2} d\tau\\
\Delta I_{L,cross}=&\frac{T}{L}k(1-D)(V_{in} - V_{out,2})\\
\Delta I_{L,fwd}=&\frac{1}{L}\int_{(D+k(1-D))T}^{T} V_{in} - V_{out,1} d\tau\\
\Delta I_{L,fwd}=&\frac{T}{L}(1-D-k(1-D))(V_{in} - V_{out,1})\\
0=&\Delta I_{L,on}+\Delta I_{L,cross}+\Delta I_{L,fwd}\\
%0=&D V_{in} + k(1-D)(V_{in} - V_{out,2}) + (1-D-k(1-D))(V_{in} - V_{out,1})\\
0=&V_{in}-k(1-D)V_{out,2}-(1-D-k(1-D))V_{out,1}\\
\end{align}

This is an equation with two unknowns, suggesting that except for k=1 or k=0, there are many possible voltages that result in a steady inductor current, but of course the real world has only one voltage. What is missing?

Simulation in LTspice shows that the output on both ends is approximately 1/(1-D) and the voltage across the resistor scales with the current ripple. This is intuitively kind of expected, but the math doesn't work out.

[edit]
I tried a simulation with two loads to ground. Very much CCM, pretty much independant of any component values. Still no way to analyse it. I also cheated a bit with the diodes.


texts: trying to use a radio shack 276-640 IR receiver module

texts:
We have a mouse (or something) getting into cabinets.  My wife doesn't want to kill it, and the no-kill mousetrap isn't catching it.  So, I am modifying a trap with an IR emitter / detector so I know when the little fella is there.  I naively bought an infrared emitter (RS 276-0143) and biased it up, and then a 276-640 receiver (with no data sheet). Using two "D" cells to create 3v rail.  I'm assuming the emitter is working.  The receiver "output" rails up to 3V when GND and Vcc are connected. A 5K resistor on the output to GND pulls it low. When I turn on the emitter 2 inches away, nothing happens.  I'm already down to .6 mA on the output with the 5K.  Any ideas?  Bigger resistor on the output?  Wrong emitter (frequency range), maybe this thing doesn't work for continuous duty?

All in put welcome, I think the mouse is getting bigger.


texts: Designing a PCB with variable-sized component alternatives

texts:
I'd like to get a little PCB manufactured with a basic circuit that I can populate with components of various sizes. E.g. have a place where any of a range of possible capacitor sizes could go. So I would have a chain of leads, like this, for example, where depending on size, I would use a closer or further-apart lead for the component in question:

---O-O-O O---

I'm finding it difficult to convince KiCad or Fritzing to let me do that. They seem to think that any component has exacly one size, and I can't find an "empty lead" part to add either.

Any advice how to best go about this?


texts: Does this clipped-sine oscillator need a buffer?

texts:
I'm considering using an Abracon VCTCXO, the
ASVTX-11-121-19.200MHz-T to run an
AT89LP428.
I'm trying to make sure that they're interoperable, but the Abracon device doesn't say anything about the slew rate of its output, nor how much clipping there is. (I realize that that particular Abracon device is listed "no last-time buy", but other devices and manufacturers suffer from the same issue.)

Reading an application guide for a similar product from a different company,
Taitien, it suggests that a buffer is needed under some circumstances:

  To convert the clipped sine waveform to a square waveform signal such as CMOS, an input buffer is necessary.  Generally, ICs that TCXO’s output going into would have input buffer functionality integrated inside the chip. Oscillator
  circuit should have Rf feedback resistor connected in parallel with the inverter. [...]

  If the IC does not have input buffer functionality incorporated, an inverter such as 74HC04 and an Rf
  resistor would need to be added in series between the output pin of the TCXO and the clock input pin
  of the IC to convert the clipped sine waveform to a square waveform

Of course, the clock fuses on the AT89 support both high-speed crystal and external clock mode. So far as I can tell, I should be using external clock mode, because the XO is an entire oscillator unit with its own power supply, not a passive crystal.

Based on these specifications:

and based on the supplies for my oscillator and MCU (3.3V and 3.6V, respectively), even in the worst-case scenario where the output from the XO is a pure, unclipped sine, the t_CHCX and t_CLCX requirements are met:

$$
t_{CHCX} = \frac 1 {19.2 \text{MHz}}
\left(
  1 - \frac 1 \pi \cos^{-1}
  \left(
    1 - \frac {0.7 \cdot 3.6 \cdot 2} {3.3}
  \right)
\right)
\approx 16.8 \text{ns} > 12 \text{ns}
$$

$$
t_{CLCX} = \frac 1 {\pi \cdot 19.2 \text{MHz}}
\cos^{-1} \left(
1 - \frac
  {2 \left( 0.2 \cdot 3.6 - 0.1 \right)}
  {3.3}
\right)
\approx 14.9 \text{ns} > 12 \text{ns}
$$

However, the rise and fall time are not:

$$
t_{CLCH} = t_{CHCL} = \frac 1 2 \left(
   \frac 1 {19.2 \text{MHz}} -
   t_{CLCX} - t_{CHCX}
\right)
\approx 10.2 \text{ns} > 5 \text{ns}
$$

So it's difficult to tell whether it will work. Since the XO's slew rate is unspecified, should I add a Schmitt trigger to be safe? Or do I have this wrong, and should use the MCU's crystal mode instead?


texts: How can I send one bit one mile with one battery?

texts:
This summer I will be attending a large music festival for the second year.  I will be going with other people this time, and I'd like to be able to communicate with the other people wirelessly in some way.  Cell phones are out, because even if you could get reception your phone dies quickly trying to fight with the other 50K+ cell phones in the square mile that the festival takes up.  Walkie talkies are difficult too- because there are so many people, nearly every channel is occupied.

I'm always open to reasonable commercial solutions but when faced with a problem like this my first thought is, what could I build?  I've got basic requirements:

A bitrate of >0b/s.  Yes, that says bits per second.  0.1b/s would satisfy this requirement.
A working distance of about 1km / 0.5 miles.  I'm willing to compromise here for...
Pocket-sized and battery-powered.  Obviously not easy but this rules some tech out immediately.

I can use one bit to indicate "meet at the designated spot".  I can use four bits if we just sync up our maps with a legend.  So, I don't need practically any bandwidth at all, which might drastically simplify some designs.  Also, I'd be willing to get any licenses I needed to work on this, but I am not currently knowledgeable about RF communication.  I do have a strong basic electronics and programming background, though, so any ideas would be helpful.

I guess my basic question is:  is there a wireless tech available that meets the bulleted requirements and would not have the problem of being completely oversaturated by having 100K people in one square mile?


texts: Why exactly a RLC Circuit powered by DC oscillates?

texts:
First sorry if the question is stupid... I am learning.

I am trying to visualize here, without equations, what happens to a RLC circuit that makes it oscillate.

Consider a RLC circuit, a switch and a 12V battery. Both L and C are initially discharged.

OK, I see that the role of the resistor is to damp the oscillations, so, lets consider R=0 and L and C are ideal.

At t=0 I close the switch.

The current starts flowing thru the resistor and reaches the inductor.

At this time, the inductor is an open circuit and the capacitor is a short circuit.

Current tries to reach the capacitor but the inductor is preventing it.
Magnetic field is building in the inductor. Current is increasing and its Voltage is dropping.

Current finally reaches the capacitor. It starts charging. Its voltage starts to rise. Capacitor is building electric field.

So at this point magnetic field is rising on the inductor and electric field is rising on the capacitor.

I understand that oscillations happen because energy is being transferred from the capacitor to the inductor and vice-versa. But if both the magnetic field and electric field are rising, how can this oscillation happen.

I was expecting to see one rising and one falling and vice versa, but both are rising when the circuit starts.

If all my explanations are wrong, please forget them and explain what is really happening in terms of current, voltages and fields to make the whole thing oscillate.

Thanks.


texts:
I'm trying to develop a replacement for a BLDC motor driver board and since my first attempt resulted in a few burned components now I'm trying to use the same components they used on the original board but I need help identifying a diode.

The board uses 3 FAN7382 as FET drivers and the schematic on the datasheet shows a diode connected in series with a resistor, labeled DBOOT and RBOOT respectively, but there is no reference to it in the datasheet.

Since I'm not experienced with BLDC motor control I have no idea of the required characteristics for this diode neither I can identify it by the marking (S1) on it.

Even the package is unusual, I'm unable to identify it. The approximate size of the diode is 2.50mm x 1.25mm and the forward voltage is 0.6 Volts.

You can see the diode in picture bellow.

Edit

I was able to figure out the reference of the diode.
It is a Bourns SD1005-S0180, it has a reverse voltage of 80V, a forward current of 100mA and 4 ns reverse recovery time.

Link to datasheet here.


texts: Low-voltage limit of quantizer such as ADC

texts:
Suppose that an input signal is very low in voltage, and one wishes to use quantizer such as 1-bit ADC. Thus, one wishes to have quantized values to be very low, also.

What is the low-voltage limit of ADC here? (theoretical)


texts: Detect IDLE status of SPI protocol under STM32

texts:
I need to know the start and stop of SPI transmission under STM32 MCUs. In my project, I send 10bytes(array) and the receiver puts them into its array.

If the receiver joins with a delay, it might lose some packages and doesn't know when it starts and stops filling its array. So it is vital to detect the transmission status.

In my structure, I use software NSS (CS is not connected)


texts:
I just had some doubts regarding voltage references, etc after viewing this circuit:

I'm usually used to using ground as a reference and assuming that it's 0V. In this case I'm a bit confused.

Q1: In this scenario, is the source of the bottom MOSFET equal to -Vgs which is equal to -Vds which in turn implies that Vgs  = Vds?

Q2: Say I labelled a new point between the MOSFETs as point B. Now could I say that the Vds of the bottom MOSFET is equal to Vb-(-Vgs) or Vb-(-Vds) or would it just be that Vds=Vb?

Q3: Lastly, If I did ground the bottom MOSFET source as usual, wouldn't the following be true
$$-V_{GS}=-V_{DS}=0$$
Now, couldn't we just exclude that last equals sign and from that say that Vgs=Vds? I feel like I've just confused myself even more. Never thought about this before


texts: Controlling a main solenoid and two sub-solenoids

texts:
I need to split an existing sprinkler zone into two zones. The issue I have is I cannot remove the valve that currently controls the flow. So, I need to have the system turn on both the original "main" valve and one of the new.

For example. Current zone 5 becomes zones 5 and 6. When the controller kicks on zone 5 or 6, the original valve also opens.

All I can come up with is maybe using 2 relays to make an logical OR circuit or maybe diodes to keep all of the lines separate so they could be tied together....

I am wondering what the best way to wire this up would be? The system is 24 VAC.


texts: Altera Cyclone IV PLL: What limits the available multiplication/division factor values

texts:
Altera Cyclone IV EP4CE6E22 with a 50 MHz input clock.
I want to get 24 MHz out of the ALTPLL megafunction.
The requested multiplication/division settings are 12/25 but actual settings turn out to be 47/98 which doesn't get an exact 24 MHz output.

What is the reason for this limitation?

Does it have to do with achievable binary representations of fractions?
I guess it cannot generate 50*12 MHz internally so it should generate a lower frequency using a non-integer multiplexer and somehow divide by this non-integer multiplexer to lock to the input frequency.

(I've found an Altera PDF about calculating achievable division/multiplication factors, but it doesn't explain what is the reason behind this limitation.)


texts:
An NPN transistor can be made a switch by applying some power to the base.
Is there a limit to how fast I can switch the transistor on and off, or I can switch it on and off as fast as I can turn the signal to the base on and off?
As switching, I mean completely off and completely on. Not in between (if there is even any.)


texts: What is a typical response time for a photodiode/phototransistor?

texts:
I'm trying to get an ATtiny26l MCU to detect a very short signal produced by a IR led + detector couple (I don't know if it's a photodiode or a phototransistor buit i think it's a diode) and the setup works if i let something fall through the couple or block it by hand but when i try to detect a fast moving object (a flying airsoft BB) i'm not getting any response. The time the IR detector is obscured is around 78μs. I'm not sure if the response failure is caused by the detector not having fast enough response time or the MCU not detecting the produced signal, but since the MCU is detecting it using a edge triggered interrupt and i also tried to check for the signal state on it's each cycle at 1 MHz i'd say it's the first option. Also is it possible for the detector to increase it's reaction time let's say in case of overload or damage?

EDIT: I also have a BJT PNP transistor invering the sensor's output (which is high at negative result and low at positive result). Could this be the problem?


texts: I know that a regular summing amplifier does \$\ V_{out} = -(a*V1 + b*V2 + c*V3)\$ but how do I invert one of the gains?


texts: Altium - Hiding connections for a particular component in the PCB designer

texts:
my question is simple: can I in Altium PCB Designer hide the connections for only a particular component?

I tried whit "View->Connections->Hide Component Nets" but this hides all the connections for every component on the board. I want hide only the connections from the header component to the others and not the connection from the IC, for example, and the other component on the top of the board.

Is it possible?

To explain better, this is my actual situation:

If I make "View->Connections->Hide Component Nets" or "N->H->O" all connection disapear (even for the IC on the top):

But I want this final situation (I photoshopped the image!):


texts: Using a centralised SMPS running off batteries?

texts:
I designed and built an analogue processing circuit for measuring power quality. I believe I made some mistakes when setting up the system's power supplies and i'm looking for some advice or general standard on what to do in this situation.

The system is running off batteries (4xAA), so over time, the supply voltage drops below the minimum needed voltage. So, I placed a centralized buck-boost to provide a stable system voltage and hooked the rest of the system supplies to the buck-boost. Below is the system supplies:

As the circuit is doing percise measurement; percision LDO's where used for ADC and offset voltages (drawing a couple of mA). What I found is the Buck-Boost switching noise was leaking into the LDO's outputs (be it Microvolts - but this damaged system sensitivity). Mistakabily, I hooked up an STM32 MCU (using about 50-100mA) to the buck as well causing system strain and leaked MCU noise into thte system.

My question - with the given 'Vout' voltages required and the supply varying from 6-4V, what would be the best practice - separating precision and the (relatively) high power supplies? I was originally thinking if I supplied the MCU separately, I would be attenuating 6V to 3.3V, burning lots of power and requiring a beefier MCU supply to handle this. Advice?


texts: Need help attempting to understand and find certain transformer

texts:
I'm building a specific circuit I found here: http://makingcircuits.com/blog/2015/07/48v-inverter-circuit.html

Part 1:

I'm pulling my hair out trying find a transformer like the one shown in the diagram. I'm pretty new to building circuits from diagrams, so maybe I've got this wrong, but it seems to be asking for a for a type of transformer which is grounded in the middle of the primary coil. Specifically it's asking for a 36v-0-36v 1000VA transformer. Is this a specific type of transformer? If so, what is it called? Please provide a link if you are able to locate one, some alternative solution,... or a correction for my misunderstanding.

Part 2:
Also, I've modified the inverter to provide 400Hz rather than 50Hz... and I would like to get approximately 570V from the secondary coil... But I would settle for less. Should I just wind my own transformer? Regardless of this question, I still need the information in Part 1 answered.

Thank you


texts: Is it possible to use a dead 9V battery as a 5V power supply?

texts: I couldn’t find anything about this online. Will a dead 9V battery (let’s say around 5.5V) act as a healthy 5V supply? Or will it deliver too little current?


texts: Is UART necessary to send AT-commands to Bluetooth module?

texts:
I'm looking to alert a connected device over Bluetooth when an accelerometer detects motion. I'm thinking of using the HM-10 Bluetooth module and an ATtiny for controlling the accelerometer.

The doc says that AT-commands can only be sent via UART. Does that mean the ATTiny will need to have an UART port? Could an ATtiny45 be used instead?

Thanks


texts: Serial bus Raspberry Pi to multiple AVRs

texts:
Background: I'm trying to replace the electronics for a ice hockey scoreboard. The old electronics had the following issues:

It stop working. I have since discovered that a couple of diodes and capacitors had burnt out.
The controller was wired. We want to get rid of the wire running down the length of the rink.
The connectors for the controller gave lots of issues. I have had to re-soldered them countless times.

The scoreboard is approximately 3.5 meters across.

I plan to stick a Raspberry Pi at the scoreboard. I plan to put a wifi usb dongle that support ap mode, and run hostapd. Scorekeepers can then connect to the Raspberry Pi via a web interface from a tablet/laptop.

I plan to replace the incandescent bulbs with LEDs, possibly OSRAM LR G5AP-BZCZ.

I originally planed to use i2c GPIO extenders. But I have since learnt that the wiring for a i2c bus need to be as short as possible. This would mean that I would need a lot of cabling from the gpios to the leds. Hence I arrive at my question.

Question: I would like to have AVR microprocessor for each 7 segment or each 2 7 segments who's job is a GPIO extender. These would be placed physically near to the LEDs. I would like to communicate from Raspberry Pi to the multiple AVR microprocessors over a common serial bus.

I have read that RS-485 can have multiple host on a bus. And as my communication is in one direction (output from the Raspberry Pi,) I hope that this can make the solution simpler.

Can the Raspberry Pi and AVR do RS-485 using there existing serial interfaces? What circuitry is needed to do this?


texts: How to select external crystal in atmega162

texts:
How to set AVR to select external crystal for clock?

A _delay_ms(1000) is producing a quick beep however it should produce 1 sec beep if it is operating on 12Mhz.

Could it be done programatically of it needs to be set using fuses?

I am using 33pf capacitor on crystal.


texts: Dead-time in Full Bridge Inverter (LTSpice Simulation)

texts:
I am trying to generate a dead time between two switching legs in the conventional full bridge inverter. However, by simply including the delay block for one pair of switches - just shifts the signal with the same duty ratio, resulting in cross conduction for the following sub interval. The duty ratio is generated by comparing the saw tooth signal against the reference sine wave.

Any suggestions how to generate pulses without cross over? Thanks in advance.

  UPDATE

I implemented dead time with the proposed RC and Differential Schmitt block. However, decided to stick with the DS. I have been trying to understand this very hard, but still no idea if the dead time is actually doing anything or not? From the graph below (top right) you can see how both pairs of switches are cross conducting even though drive signal clearly has a specified dead time (below). I also varied some of the SW parameters, but didn't see much of a difference apart from more graduate, softer transitions. Any idea if I should dwell on this further or can I just assume that they are "successfully" driven with a dead time?


texts: Why does a fuse voltage rating only signify the dielectric strength?

texts:
From what I understand, a typical fuse wire will melt once it's current rating is breached by some factor.
However, a fuse also has a voltage rating, which signifies its dielectric strength. From what I've read, this voltage rating means that, "beyond this particular voltage, the fuse may conduct electricity even if the current being drawn is much much higher".
Does this mean that 1A @ 5V and 1A @ 100V builds the same amount of heat in a fuse wire? It shouldn't theoretically since the power rating P=VI is way different, right? To put it in another way, can I use a 1A @ 220V fuse in an environment of 1A @ 5V?


texts:
I am trying to construct a simple MOSFET switch to control the input line of a linear regulator, but I am quite baffled as to how this works from the simulation I have done.  The pulse input simulates a microcontroller drive, and I've simulated the input impedance of the regulator with a big resistor.

I was expecting the output to go to close to 0V when the drive pulse is high.

The images show my test circuit and the gate and output voltage waveforms, can anyone shed any light on what basic error or misunderstanding I have made in my circuit or simulation?


texts: Why does 60 Hz mean 60 refreshes and not 120?

texts:
A light bulb using alternating current at 60Hz turns on and off 120 times per second but in a monitor 60Hz means 60 refreshes per second.
Why is that? Shouldn't 60Hz mean 120 refreshes?


texts:
I'm building a simple pierce oscillator for fun and trying to read the frequency using an arduino uno and the freqcount.h library (I don't have an oscilloscope). However, I'm consistently getting a reading of 0 Hz when the resonator I'm using is labeled as 4.096MHz. Below is the circuit I put together, the top part is a simple inverter and the rest is from a diagram of the pierce oscillator I found on wikipedia. I calculated the values for the capacitors based on the 20pF capacitance of the resonator (and assuming 5pF capacitance of the inverter and stray capacitances). Even if my values were off, however, why would I get a reading of 0Hz? Please be gentle, I'm a beginner. Thanks.

simulate this circuit – Schematic created using CircuitLab


texts: Boolean algebra -- minterms for 1:1 inputs and outputs

texts:
Let's say we have a truth table with two inputs (A, B) and one output (X).

A
B
X

0
0
0

0
1
1

1
0
1

1
1
0

I know that I can write a boolean function by (a) choosing rows where X is 1, (b) writing the minterms for these lines and (c) write cannonical sum of products (CSOP) like this:
$$
F(A,B) = (\overline{A}\cdot B) + (A \cdot \overline{B})
$$

But how do we use the same principle if there is only one input (A) and one output (X) i.e.:

A
X

0
1

1
0

Does minterm even exist in this example?

Or maybe even this (X is constantly 0):

A
X

0
0

1
0

Note:
I want the correct mathematical derivation of these simple examples.


texts: Tolerance on SMD Aluminum Electrolytic Capacitors

texts:
I'm searching for some polarized surface mount device capacitors on lcsc.com and notice that they only have tolerances of \$20\%\$ tolerance devices in their catalog for this type of SMD device whereas the through hole counter parts have much lower tolerances. Is this normal for this type of device? My inherent feeling is that a \$20\%\$ tolerance is rather large.

edit:

The capacitors will be used in a Li-Po charge management circuit as shown below:


texts:
Another basic question to understand. It is well known that the transfer function of a low pass RC filter in Laplace domain is \$V_o(s)/V_i(s)=1/(1+sRC)\$. Now sticking to this format and taking inverse Laplace transform \$V_o(t)/V_i(t)=e^{-(t/RC)}\$. All text books have the time domain equation as \$V_o(t)/V_i(t)=1-e^{-(t/RC)}\$ considering a step response as shown in the picture attached. But if i was to strictly follow \$V_o(s)/V_i(s)\$ and its time domain counterpart, without specifically mentioning that \$V_i(s)\$ or \$V_i(t)\$ is a step response then how are the first two equations similar? What am I missing here?

Also if i am correct if \$V_o(t)/V_i(t)=1-e^{-(t/RC)}\$ then \$V_o(s)/V_i(s)=1/s(1+sRC)\$ and not what is shown in \$V_o(s)/V_i(s)=1/(1+sRC)\$.
This is really driving me up the wall.


texts: Geometrical Parameters of Induction Motors

texts:
How does one relate the Thevenin equivalent circuit parameters of an induction motor to the physical geometry of the motor?
I am particularly looking for the transient torque of a single phase induction motor analysed within the context of Maxwell's equations if possible. The problem is that a superficial analysis of the torque vs speed yields a direct proportionality relation as expected, but it doesn't display the torque decrease to zero near synchronous speed.


texts: I load a project into the chip STM32f103ZC whose internal sram is 48kBytes , there are also 2MBytes external sram on the board. But when I download and debug the project,the map file tells that 52KBytes read write memory has been used. Does it mean the ram? I think it doesn't exist error maybe because the linker command file makes 64KBytes for the ram just like the datasheet as below, but where is the extra data? Is it automatically stored in the external sram? I use the IAR under the Windows in C language.


texts: Charging Li-Ion with BMS and CC-CV DC converter

texts:
I'm currently building my own electric longboard and even though I looked through some resources considering this, I am not a 100% sure that I am on the right path.

I want to use a 10S2P battery pack, consisting of Samsung's 30Q 18650 and I bought a 10S BMS with balancing capabilities.

Now I need to charge the battery pack. Since it is 10S the charging in the first stage would be 42V for CV and below 6A for CC. I saw videos online where they simply use a Buck-Boost-Converter, which is capable of CC-CV. To my understanding, that would only cover the first stage of the charging process.

Questions:

What happens afterwards, if the CC-CV converter is still connected, even though first stage is over? I somewhere read, that CC-CV is from an electronics point of view simply CC, so the voltage might vary. Are there fatal consequences to be expected, if the converter is connected for too long? What happens in that case?
If the first stage is over, there might be a chance that the CC-CV converter (which is really only a CC as I read, in case that's even correct) puts out more than 42V which is definitely a hazard for the Li-Ion cells. But since I am using a BMS (with overvoltage and balancing capabilities) I should be safe from this, right?
Are BM systems in general capable of doing overcharge protection? voltage- and current-wise? So simply put: Can I connect the BMS to CV 42V and it will take care of everything?

I could not really find specific answers to these questions, but hopefully you can enlighten me.

Thanks in advance.


texts: What process detects whether two I2C master devices send conflicting messages?

texts: I'm curious - if two I2C master devices are sending commands or messages at the same time that conflict, is there any process that detects it ? What does that process do ?


texts: Mechanical relay: higher current than rated current at lower voltage than switching voltage

texts:
In general, is it advisable/safe to switch a mechanical relay with the following abstract conditions?

load voltage << rated switching voltage
load current > rated current

Relevant Questions

Relay: higher voltage allowed at lower current? states the following

  The current rating is to limit the self-heating of the relay due to its own resistance.

Understand Relay Specifications to Get the Most Out of Your Switching System

  maximum current that the relay can sustain when being opened or closed and not sustain contact damage

My Use Case

I have a mechanical relay (Digi-Key PN 281-6348-ND) with the following specs:

Switching Voltage: 250 Vac
Contact Current Rating: 10 A

I would like to use it to PWM control a 12 Vdc thermoelectric plate (Peltier module) rated to pull up to 15 A.


texts: is it true that whether a POS can read an NFC card, that POS is compatible with HCE?

texts: I was wondering if the host card emulation would produce the same result as an physical contactless card is producing.


texts: Why do cables and batteries have a positive and a negative side?

texts:
I am a beginner in electronics, mostly self-taught. If electrons are negatively charged and are the reason for electric current why is there a 'positive' side on a battery and negative one? Don't electrons just flow out of one of those two sides? To my knowledge only one side pushes electrons and the other does nothing, how exactly does this work?

What is a 'ground' anyways? I have read that the negative side is the ground and yet it is the side that pushes electrons in a battery, is that correct?


texts: Why different SFs in LoRa are said to be orthogonal?

texts:
As orthogonality is an important characteristic in LoRaWAN but most public references just make a conclusion that different SFs are orthogonal. This confused me a lot and hope to make a clear understanding.

As @Chris Stratton show me in the link http://www.sghoslya.com/p/lora_6.html, I can tell different signal from different SF and BW combination. But I still feel there's a gap that why this suggest orthogonal?

And the frequency-time figure is not the common frequency-amplitude figure that shows signal in frequency domain after Fourier Transformation. How this frequency-time figure used in real signal processing step?

Also, in https://lab.dsst.io/slides/33c3/7945.html, the author suggested in page 80-83 the demodulation of LoRa.  It leaves me the question that why up-chirp multiples the down-chirp result in a constant frequency?

I know from my previous study that the multiplication in time domain equals the convolution in frequency domain. So how does the de-chirp result make sense?

Thanks for @Neil_UK's kind suggestion: )


texts:
How to set RN171 module work on UDP?

www.aisgps.com/udp.jpg http://www.aisgps.com/udp.jpg

for i have look the user munual,but always failed.

Anyone knows how to set,pls give me some advices.
thanks.


texts: Could this simple circuit charge li-ions in parallel?

texts:
My goal is to design a circuit that can reliably charge 3.7V li-ion batteries in parallel for extreme high current applications (think over 100 amps).  Normally, I would just buy a cheap li-ion balance board, but I can't find one that can handle the currents in any sort of compact form.
So I designed this fairly simple charging circuit:

Since each cell caps out at 4.2V, I could just supply them all 4.2V limited to 500mA charging current. Once each battery reaches 4.2V, it stops drawing current.  This would ensure that each battery gets to 4.2V without overcharging, right?
I've never seen a battery charger designed this way, so I'm assuming it has some sort of fundamental problem.  Is there any reason why this wouldn't work?


texts: My simulated coax cut off frequency is way far off the calculated value

texts:
I used the lumped model to model a coax cable as a low pass filter in MATLAB. I also included ESR which is supposed to resemble the dielectric losses.
I derived my transfer function from the circuit below. I used voltage division to get my transfer function.

simulate this circuit – Schematic created using CircuitLab
My MATLAB code has the transfer function "h" I derived:
    Fs = 0.002;
    s = 10: 1/Fs: 2*pi*1E9;
    d = 1E-3;
    D = 3E-3;
    er_d = 1/(0.66)^2;
    mu1 = 1;
    mu2 = 1;
    row1 = 0.234;
    row2 = 0.234;
    eo = 8.85*1E-12;
    mu_o = 4*pi*1E-7;
    ed = er_d*eo;

R1 = sqrt(s.*mu1*mu_o/(2*1/row1));
R2 = sqrt(s.*mu2*mu_o/(2*1/row2));
Rs = R1+R2;
%lumped model
L = mu_o/(2*pi) * log(D/d);
C = (2*pi*ed)/log(D/d);
R = Rs/pi .* (1/D + 1/d);
ESR = (1/(10E18)) ./ (ed * s.^2 * C);
%ESR = 0;
h = (1./(C.*s.*1i) + ESR) ./( 1./(C.*s.*1i) + ESR + R + L.*1i.*s);

figure(1)
plot(s, 20*log(abs(h)));
set(gca, 'Xscale', 'log')
ylim([-8 0])
title('Coax cable modulation')
xlabel('Frequency in Rad/s');
ylabel('Gain in dB per meter');

grid

fc = 3E8/(pi*(D+d)/2 * sqrt(1*er_d))

My -3dB frequency from the resulting figure is in the MHz when it is supposed to be in the GHz. Why is that? I would truly appreciate some help. Thnx :D


texts: What does Vivado HLS logo on the following blocks indicate?

texts:
As you can see below there is Vivado HLS logo on two blocks:
madd_1, mmult_1 and not on madd_1_if and mmult_1_if.

Why is that so?


texts: Does reversing polarity in AC damage the equipment? (Sonoff Wifi Switch)

texts:
Firstly, I am a beginner. Excuse me if this is a dumb question.

I have ordered a Wi-Fi switch named Sonoff. I have a doubt whether the device will work if the polarity is reversed or will it get damaged?

If I'm correct, AC doesnt have polarity right? Then why do the manufacturers specify Live and neutral on the components?

So can I interchange Live and Neutral on this component?

Thanks in advance!!


texts: Limits to transistor current source / mirror?

texts:
Are there any low end limits to how low of a constant current you can make with a transistor ?

For a simple circuit like the following, is there a lower limit to the achievable constant current ? Would 100uA-1mA be asking too much ?

I'm not that concerned with (yet) about the temperature effects of the current (that might be a seperate question).

I've sim'd it, and everything appears to be in order, but are there any practical limits that a simulation will exclude ?

simulate this circuit – Schematic created using CircuitLab