texts: PSpice - simulation worst case - delay on AND gate?

texts:
I have a question to someone who is familiar with PSpice analysis. I have a simple circuit as below and everything works good with "typical" simulation - dstm1 gives positive impulses continously and couter 74393 count till output A and C have high signal, then via AND and OR gate signal reset 74393 counter. When I change simulation to "worst case" I have situation when output C has high signal and in the meantime it is rising signal on output A and clr (counter reset). Is it possible to make some delay on AND gate? Or is it other way to fix worst case simulation to make it works properly? Thank you in advance for any advices.

Typical:

Worst case:

Worst case with lower frequency:


texts: Write operations on eMMC chip (not SPI) with data incoming from MCU

texts:
I'm working on integrating an eMMC ship to a FPGA.
As for now, the initialization is working fine, I've managed to receive the CSD and CID registers properly, and I can select and move the chip to Transfer State.

The way my design is built, I have to send data to the FPGA from the MCU, that can then be forwarded for programming into the eMMC.

My question is, how am I supposed to do that properly, what is the good design pattern for this? Some kind of buffered FIFO?
The MCU/FPGA communication being serial, in order to have a full byte to send I need 8 SPI clock cycles, while I need only 1 MMC's clock cycle to send it to the MMC, its link being parallel. And I can't make the MMC wait for the next byte to be ready, otherwise I'll just be programming the previously set bits for the amount of mmc's clock cycles needed for the next byte to be received.

The FPGA clock is 12MHz, SPI's is 1.5MHz, MMC's is tuneable up to 12MHz.
A full block of data is 512 bytes, that's a logic vector of 4096 bits that I'm guessing I shouldn't allocate as a buffer, right?


texts: PWM control of Peltier with Arduino+Thermistor

texts: I currently have this setup and would like to add automatic control over the PWM based on a thermistor reading. Any insights?


texts: VReg with MIC5156, why a so high drop-out voltage?

texts:
I'm building a voltage regulator with a mic5156 (datasheet). I wired it as this
(coming from the datasheet Figure 1C ):

With this design, I need to input more than 8 volts in order to get the expect
ouput voltage of 6.2v. If I raise the input voltage more than 8v, the output is still regulated
to 6.2v.

As the Mos (datasheet) has a very low Rds, I expected a nearly null drop-out voltage for the 50 mA
output current which is not the case (around 2v).

What's wrong?


texts:
I've been looking into the schematics for some Arduinos in detail to increase my understand of them. Take in particular the Arduino Zero schematic, we can see the RX/TX LEDs are connected as:

simulate this circuit – Schematic created using CircuitLab

As per my understanding, the MCU pin can sink 10mA of current. How is the value of R1 (330\$\Omega\$ in this case) chosen? Assuming we have an LED with a forward voltage of 2V and current of 20mA. (I don't actually know what type of LED is on the Arduino Zero - any ideas?)


texts:
While I can understand the logic behind synchronous counters that can implement 'any-sequence',I'm not sure how I would go about doing that with an asynchronous counter.

For example one that produces a 2->3->5->8->13->2->3->... sequence.

Any tips?


texts:
I'm a homebrewer. I use 5, 4 legged 200 liter tanks to ferment the beer.

I would love to be able to weigh the tanks and have the signal on my PLC to see how much I have in the tanks.

Each tank weighs 40kg and if it's totally packed with beer, it weighs 250kg, which means that one leg carries a maximum of 62,5kg.

I'd like to use these very cheap load cells. It is said in the documentation that if I use two I can weigh 100kg, which is enough per leg, so I would need 8 load cells per tank.

But how do I connect the load cells, and how do I get the signal up to 5 - 10 volt for the PLC?

The wires from each leg will go to a box mounted on the tank. The box shall contain the electronics needed to join signals from the 8 load cells and send a single the 5 - 10 volt signal to the analog input port on the PLC per tank.


texts: Drive a 20A load (12V) with an MCU at 3.3V

texts:
I need to switch on/off a cooler system that draws 20A at 12V using an ESP32 GPIO pin.
The ESP32 GPIO pins work at 3.3V logic with maximum 40mA of current.
Do you have a simple and safe solution to solve this problem?
I thought of using a MOSFET (e.g IRL540) with a resistor of 1k between the GPIO pin and the MOSFET gate:

simulate this circuit – Schematic created using CircuitLab
Could it be a good solution?
Editing afters some comments
The cooler system is composed by three Peltier Cells that drains maximum 20A. It is attached to a power supply that transform 220AC to 12V DC - 20A max.
Diode between Drain and 12V to protect the MOSFET
I've updated the schema with the diode between drain and 12V, Can you please confirm is it mounted in the right way? Thanks


texts:
I'm having a hard time understading the workings of the LEM LV 25-P

I can't figure out the use of that op amp and how does the ratio of the sensing equals to 2.5*RM/(R1+R2)

Here is a picture of the LEM LV 25-P

And is there any possibility to simulate it is Pspice/Ltspice ..?


texts: What is the best way to convert a 10V power supply into a 5V power supply?

texts: If you were given a 10V power supply and wanted to power USB devices with it, how would you convert it to 5V? Would using a voltage divider splitting it into 2 5V lines be the best? What ohm resistors would you use? I believe using any two resistors of the same value would split it into 5V. Why exactly would the resistance values matter?


texts: Charging all night and its effect on the charger

texts:
I googled about this topic and I found that keeping the charger plugged in the wall for days will consume a very small amount of energy and will not cost too much. And most of smart phones disconnect the battery from the charger automatically when the battery is fully charged. So The battery, The phone, and The money are in safe.

What about the charger itself? If I keep it plugged in the wall mains for all night or for many days, Does that affect the life time? I would NOT like to buy a new charger every month :)


texts: How does a wireless device alert the master to its presence without interfering?

texts: My understanding is that wireless devices, such as a cell phone, must speak to a master device like a cell tower and the cell tower will then arbitrate who gets to talk and when. Maybe my understanding is wrong, but assuming it is right, how do the devices even request their turn and alert their presence without stepping all over the communications already there? In a video explaining the process, it used an example of one teacher and many students and the students must raise their hand and have the teacher select them to talk individually or else [s]he can't understand anything. But how do they raise their hands? In a wireless world, I imagine they'd all be shouting "Teacher call on Sam!" "Teacher, call on Jenny!" simultaneously and all while someone else is talking. So how does it arbitrate without confusion?


texts: Wondering how to get inexpensive 10 mA power supplies for electrochemistry

texts:
As part of my graduate research on electrochemistry, I'm looking for a way to have 10 or 20 inexpensive, low amperage, constant current power supplies that simply hold at 10 mA with reasonable accuracy, +/- 1 mA.

My first thought was to purchase a bunch of wall chargers like these ones, cut the jack off it, split the wires, attach a 10 ohm resistor inline then attach some leads. Then I would buy a power strip and plug all of them in and have one "power supply" per electrochem experiment I'm running. But I'm not sure if that would work because I'm unsure if these adapters are constant current or constant voltage. I definitely need CC.

Even if I did make this small army of power supplies, how would I go about measuring them for accuracy? I'm not sure how good my cheap $10 multimeter is at measuring ~10 mA while the electrochem is running, and I'm not sure how much measuring the system affects the current while it's being measured. If anyone has a suggestion for a good multimeter/current measuring device at such low currents, I'd love to hear it.

The answers so far are very helpful. Thank you all very much. I have a lot of reading to do to learn everything presented so far.

Edit in response to expected voltages and chemistry details:

I ran a solvent system yesterday which required 5-7 V (currently using cheap, 10 A power supplies for our initial runs), but today I have another solvent which requires 22 V. I don't think the experiments will require anything more than 25 V.

The electrochem experiments involve using rare-earth metals to make/break chemical bonds. We'll be running them with 5 - 20 mL of solvent in a divided cell reaction flask using organic solvents like acetonitrile and acetic acid, and organic salts as electrolytes. The divided cell has a cathode on one side and an anode on the other, separated by a fine frit. The experiments will run for at least an hour, up to 24 hours in some cases.


texts:
I have to square wave signals with the same frequency where one is delayed compared to the other.
Put two signals to the input of a NAND gate (two inputs).
Is there way (math, or some kinds of proofs) to see that the output signal of NAND gate also has the same frequency as the input signal?


texts: Does the altera ROM megafunction have a startup delay?

texts: I'm trying to make a very simple single cycle CPU in VHDL. My machine code is stored in a ROM that was made by the Altera MegaWizard. The first word that is stored in this ROM is 0x1111. After writing a testbench for the CPU, I found that there is an initial delay of 1 cycle when reading from this ROM. Is this normal and is there a way to fix this? Would this delay even matter in my CPU?


texts: Implementation of a NOT gate with two transistors - Why not one?

texts:
I just encountered this implementation of a NOT gate:

My question is: Why do we need the lower transistor? Why can't we do this:

Thanks!


texts: BJT analysis resistance at the base using voltage divider

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im currently confused as to why the resistance at the base is R1 || R2, ive done some research and looked at a couple of responses from people. But i still dont quite understand, could someone help me clear up my confusion please?

Some one has said:

If we assume that and ideal power supply has an impedance of 0 Ohms with respect to ground then both of the ends of the divider are connected to 0 Ohms with respect to ground and as far as impedance (or resistance) is concerned the two are in parallel.

If you take an ideal battery and draw some current from it, ideally the voltage will not change.We say that an ideal battery has an internal resistance of zero ohms, and that is because if you put current into or take current out of an ideal battery the voltage will not change.

If you take 100 microamps into or out of the divider in the circuit below you will see the voltage at the output of the divider change by 100 uA x 16k = 1.6 volts. (perform the experiment and see). An ideal power supply has the same 0 Ohm internal resistance as the battery.

Could some please help me understand what he means?
Please no smart answers like "he means exactly what he's wrote"


texts: Intuitive meaning of setting determinant = 0 in oscillator analysis

texts:
I'm reading a book on oscillators at the moment and the author is explaining a method of analysis based on the system determinant.
Given the following generic FET tuned oscillator arrangement:

and the corresponding system of equations determined by mesh/loop analysis:

The determinant is obtained:

The author then comments that the "conditions for oscillations can be obtained by setting the system determinant equal to zero"

I'm struggling to understand this in an intuitive way.  I'm almost there (I think), I just need a little push!

Here's what I think this exercise is about:  the system determinant is a way of determining the equivalence of the slopes of the linear equations involved.  In the event that the determinant is 0, then the slopes are either the same or parallel (either infinite solutions or no solutions).  So, if these equations were referring to phasers, a zero determinant might suggest that the slope of the phasers were equal.  Which in turn might suggest that the phase was zero (a condition for oscillation).

EDIT: a corollary of that thought is that the two equations are significant in the sense that one defines the "amplifier" and the other the "feedback".  Then the phase relationship between the two is zero for oscillation.  Is that what zero determinant is solving for?

But, I'm sort of guessing here.  Can anyone give me a more comprehensive and intuitive understanding of what this means?


texts: Convert perpetual magnet motor output to 5 volt DC

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Disclaimer: Hi, I was in the neighborhood (StackOverFlow) and just noticed this cool site. I have had this general wondering for a while now and I am not sure if my question is constructive enough for this site (not from EE background). But I am genuinely interested to learn/know if there's any practical use of the concept. So, please do keep an open mind and  any explanation would be greatly appreciated.

Concept: Let's say I have a DC motor (12V, 0.5A) and I managed to keep it spinning by "strategically" attaching some neodymium magnets around it (my intention is not to start a war regarding whether or not it is possible, but for the sake of practical usage, let's assume it is possible). The output I am getting is 7-9V, unknown amperage.

Question: Is it possible to convert this variable output to a stable 5.0 volt (standard USB output) with 0.5-1.0 amp to charge cellphone and if so, could anyone please provide some resources / explanation / diagram?


texts: AC/DC coupling and DC offset to read DC voltage in analog oscilloscope

texts: A function generator is connected to an analog oscilloscope. I can see a sine wave. Can I read DC voltage with the help of DC offset knob? If so, can the minimum DC voltage be negative?


texts: Can I control a load of 12v DC with a solid state relay 24-380VAC?

texts:
I need to control a load of 12v DC and 30A, Can I control the load with an  AC solid-state-relay 24-380v and 40A? If it isn't possible, what should I use?
Thanks.


texts: Why do dead batteries appear to recharge on their own after awhile?

texts:
The other night, I found myself crashing at a friend's house without a MicroUSB charger handy. As such, my phone (Nokia Lumia 920) died before I went to bed - attempting to boot would simply yield a "low battery" screen. When I awoke about 6 hours later, I decided (in a moment surely befitting the definition of insanity) to try turning the phone on again. The phone booted this time, showing about 12% battery remaining. Aside from the expected "low battery" warning messages, I was allowed to use the phone normally for awhile before I finally got back into my car and was able to charge it there.

I'm pretty sure I've seen this phenomenon in other small electronics (usually phones). A device will have drained its battery to the point of being un-bootable but, after a few hours or so, I'll later try again and find it coming to life as if nothing was wrong.

What causes this?


texts: Best shunt resistor for power meter application?

texts:
Looking for a shunt resistor for measuring power usage and was wondering if anyone had any experience with these.

It should be capable of handling 110V/20A in-home circuit.

EDIT: Energy monitors are the rage these days and I was thinking about putting a simple circuit together to try out. This would be used to measure a typical appliance or electronic device such as stereo or television. Similar to a Kill-a-watt or multimeter. I haven't really thought about accuracy as much as getting something to work well. I haven't thought this all the way through just thought maybe some here may have already "been there done that".


texts: Why are the two rectifiers in an AC Power adapter?

texts:
I am currently learning how an AC Power adapter works, and I learned that the incoming voltage is first filtered, then rectified, then converted back to AC using a transient switch, transformed, then rectified again and output. Why is the first rectification needed?

German drawing:


texts: 220v to 9 v transformerless power supply

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I wanted to turn 220 volts to 9 volts in order to turn on a touch switch , so i used the circuit below but there was a warning in the description which mentioned not to touch the circuit at all ,
is this a suitable circuit in this case ? because it doesn't have a transformer , is it safe ?
Do you have any suggestion to turn 220v to 9v DC without using transformer and still be safe ?
Thank you


texts:
I have an assignment where the PIC is clocked at 16kHz and the output of the the PWM has to be on channel two. The PWM frequency has to be 400Hz and the duty cycle is 10%

Following the manual I derived the following values for the PR2 registers(PWM Period) and then the CCPRIL:CCP1CON<5:4> registers (PWM Duty Cycle) respectfully.

PWM PERIOD:

$$\ \ PR2 = ( \frac{PWM Period}{( T_{OSC} \times 4 \times \ TMR2 \ Prescale \ Value)} ) - 1 $$

$$\ \ PR2 = ( \frac{0.0025
}{( 0.0000625
 \times 4 \times \ 1)} ) - 1 = 9$$

PWM Duty Cycle in % = 10

PWM Duty Cycle (in time):

$$\ \small CCPRIL:CCP1CON<5:4>  = \large ( \frac{ 0.1 \times \ 0.0025
}{( 0.0000625 \times \ 1)} )= 4$$

So PR2 = 0000 1001 and  CCPRIL:CCP1CON<5:4>  = 00 0000 0100

But my problem is that I used an online calculator and got the following result instead.

  /*
 * PWM registers configuration
 * Fosc = 16000 Hz
 * Fpwm = 400.00 Hz (Requested : 400 Hz)
 * Duty Cycle = 10 %
 * Resolution is 5 bits
 * Prescaler is 1
 * Ensure that your PWM pin is configured as digital output
 * see more details on http://www.micro-examples.com/
 * this source code is provided 'as is',
 * use it at your own risks
 */
PR2 = 0b00001001 ;
T2CON = 0b00000100 ;
CCPR1L = 0b00000000 ;
CCP1CON = 0b00111100 ;

I would have expected the LSB in CCPIR1L to be 1 and CCP1CON<5:4> to be 00 Since the value calculated is 4 and 4 in binary is 100 CCP1CON<5:4> contains the two LSBs of the duty cycle value. However it's not according to this calculator and I'm just wondering where I went wrong.


texts: How do VA and W ratings of UPS supplies compare with mAh ratings for power banks?

texts:
I'm trying to figure out how to power a few devices during power outages.  I've looked into UPS devices and also portable phone power banks.  My biggest problem is how to compare the devices, apples-to-apples.  The UPS we're looking at claims to provide 600VA/330w, and it has only 120V (AC) outlets.  The power bank claims it provides 20,000 mAh.  It has both USB ports and a 120V (AC) output.  How do I evaluate how long each device will last?  It would be helpful to know how to convert VA or W from the UPS and mAh from the power bank in like terms.
We have two devices to power.  First, we'd like to be able to charge a Moto e4plus phone.  The battery itself is rated to 5,000 mAh.  It charges through USB, and as far as I can tell it draws 1.9A while it charges at 5v.  A full charge takes 2-3 hours.
The second device is our cable modem.  The modem is a Technicolor TC8305C.  The modem plugs in to the AC mains and the label says it draws 1.2A.  The modem itself does have the capability to use its own battery for reserve power.  We don't have one, but I've attached a picture of one.  Perhaps that might give a clearer picture of what DC power it actually consumes.

Thank you!


texts: How does a CPU interface with GPIO pins?

texts:
I am trying to implement a simple mips1 clone in Verilog at the moment, works all fine in simulators but I also want to run it on an actual FPGA.

Basically I would like to send/receive characters to the running CPU via UART, also I would like to read values from buttons/switches on the FPGA. Now I'm wondering what is the best way to interface GPIO pins and UART.

The only idea I could come up with is to just have separate chips running on the FPGA, directly connected to the GPIO pins and to the UART interface. These chips would just read from/write to specific memory locations and do their job based on that data.

I could also imagine that I will need some kind of interrupt controller for this so the CPU could run some snippet of code when a button is pressed. But I can only imagine this to be useful for input from something, not when I want to make an LED light up.

How does a microcontroller or a Raspberry get an LED to light up?


texts: Daisy chaining power through mcu modules

texts:
I am really sorry if the following question is too obvious and basic, I am trying to understand how I can do this right.

I have five 5V PIC custom modules that I am trying to power, using a daisy chain. These are just PWM generators with a few LED indications. The current draw of each module is about 30mA. So my total current consumption is around 150mA.

I have a 12V to 5V, 3A converter as my power source and is daisy chained to power these modules.

The problem I am facing is that every time I power this system, one module resets unexpectedly after some time. But when I power it and test it individually then it works fine. I also placed another module in that position and it behaves the same way. So I assume that it is resetting due to brown out reset whenever the voltage drops below 2.7V.

If this is true, why is my voltage dropping below 5V in this daisy chain?
Is it because of branching?

The wires I am using for daisy chain are solid AWG 20 wires. I have soldered these wires to 5 screw terminals on a prototype board. The PIC modules don't have decoupling capacitors between its Vdd and Vss, I am suspecting that this might too is affecting the operation. PIC used is PIC16f18344.

I tried searching online for techniques for implementing daisy chain and related design considerations, but had no luck.

Please advise what I must be missing here and/or if I did not consider some requirements.

I have shown a simple connection diagram of all the blocks involved. Please excuse how the diagram is extremely basic and confusing. The green small boxes are the screw terminals. and the black wires are just indicating how the positive and negative lines are running from the source.


texts:
I have an enclosure containing an earth ground line. It has a brass earth ground bus that is connected to:

the input earth pin of a 120V single-phase mains IEC320-C14 connector
the output earth pin of a 120V single-phase NEMA 5-15R connector
earth terminal for a self-contained SMPS with a metal case

The enclosure is ABS, so I haven't bothered to ground it.

I'm considering adding another ground connection from the bus to an L717SDE09P DSUB9 connector. The connector shell is tin-plated steel. It has "grounding indents" which I assume are the indents on the exterior (pin) side of the shell.

Currently I'm considering running a copper stranded wire from the earth bus to something in the ring crimp category. The ring would sit on the interior of the enclosure between a washer and a nut on one of the DB9 shell's jack screws. Is this a viable approach? Is there anything I'm missing?


texts: Best practice for synchronizing VHDL stimuli with circuit

texts:
What is the best practice or method for synchronizing stimuli input and output with a sequential logic block in VHDL?

I am currently running only behavioral simulations, but I want to make sure my test bench will also work appropriately with timing simulations. I am testing various entities I am writing for handling modular addition/multiplication and a divider before I connect them all together. All sequential logic is written to use the rising edge of the clock.

I was originally providing stimuli at rising edge of the clock at the start of the simulation and waiting for whole multiples of the clock period before checking the results, however, I found that the logic would miss some inputs or take a cycle longer than expected. I've since come to the conclusion that, since inputs need to be stable at the rising edge of the clock, I should be changing stimuli only at the falling edge of the clock. I am now using a wait statement to align with the falling edge of clock and, for logic that take a well-defined number of cycles, wait for the appropriate number of clock periods and check the results. This seems to fix the issues I was having, but is this a recommended practice or should I use a different approach?

Also, when waiting upon output signals such as a ready or ack signal, should I combine that with a wait until rising_edge() and ready = '1', or keep everything, output and input, aligned on the falling edge? Currently, using rising edge for outputs seems to be working.


texts: Confusion with serial communication standards when sending sync serial data to a PC thorugh its serial port

texts:
When I read about SSI communication I can see that a pair is used for clock and another pair is used for data transmission as follows:

On the other hand if I read about RS422 all lines are data and there is no clock:

I'm a bit confused about hardware standard and communication standard here. As far as I know the RS232 port of the PC is used for async serial communication but SSI is sync serial communication and the RS422 converter will only change voltage levels not the communication mode(it wont change sync to async).

Now if the data from an SSI sensor to be sent to a PC which has RS232 port, would an RS422 TO RS232 converter work? Or one needs another approach or interface?


texts: ATMEGA328P standalone sketch doesn't work as expected

texts:
As I finished programming the MCU in the Arduino Uno board to receive some RF Signal and drive relays, I moved it into a standalone board I made with Eagle. The circuit is pretty basic, the MCU receives data from a RF Receiver, processes it and then turns on/off some pins that drive 5V relays (through transistors, of course). When I test it on the Arduino Board, you can see that the LEDs toggle ON and OFF whenever I send the data through the RF Transmitter. You send once, it toggles ON, you send another time, it toggles OFF and so on. This works for all the 4 PINS that it has programmed. In my standalone board, each of these four pins are connected to transistors that drive 5V relays. The problem is that only one pin seems to activate, and then it won't even toggle OFF, like you send the data once and you can hear the relay's coil go ON, but then if you try to toggle it OFF it just won't, it's latched ON and I have to unplug and plug the USB cable again to reset it. The ATMEGA328P has a 16MHz crystal, two 22pF caps for the crystal, and a 10K resistor that goes from the Reset Pin to VCC. I'm not sure why the MCU behaves so weird in my board. There's also another VERY weird detail I didn't mention. If instead of using the RF Receiver, I connect the Data Output pin of the PIC that drives the RF Transmitter directly into the Receiver board, that one pin I mentioned that works is able to toggle OFF and ON again, but still, the other pins just don't work. I've tested it not only by hearing the relay's coil but also by using a multimeter. Any help would be really appreciated.

EDIT:

Here is the Eagle Schematic of the board:

It's true that I really didn't concern about the noise, but since it was quite a simple project I didn't think that noise was going to attack so violently, plus
I don't really know how to protect the circuit from inductive noise. Thank you for answering fast!

EDIT 2:

Okay so here goes more detail:

Real photos:

The soldering seems quite awkward but I probed all the traces to check for continuity.

I could make some extra holes to, for example, add a 100nF decoupling capacitor for the MCU and so, but if you think I should enhance the schematic and add a lot more components, then I'll gladly remake the board.

About the supply, right now (for debugging) I'm connecting the Arduino Uno to a Cellphone Charger (Notebook won't supply enough current for relays), and I'm connecting those red and black cables to the Arduino Uno. I'm using that Cheap 433MHZ RF Receiver so if the circuit is so vulnerable to noise as you say, it may also be getting fouled up by the noise.


texts: Wireless power transfer - 6.78 MHz resonant circuit

texts:
I work on wireless power transfer. I used (EPC9065: High-Frequency ZVS Class-D Power Amplifier)
I have a resonance circuit series-parallel topology work on 6.78 MHz, when I connect the circuit and applied voltage at the beginning there is a power transfer, and the circuit work properly. When increasing the voltage source gradually after minutes of applied different voltages there will be a drop voltage and the efficiency drop. I need to know what are the causes of drop voltage, how could I choose the appropriate capacitor in order to maintain the circuit working properly


texts: Switching supply burning mosfets, what is happening?

texts:
I have been working on a SEPIC converter for an electronic cigarette power supply.  This application involves using two 3.7v INR batteries in parallel, rated for an appropriately high current discharge, to power the converter and drive a kanthal heating element with a DC resistance ranging from about 0.5 ohms to 2 ohms.

I am driving the SEPIC MOSFET with the PWM output of an atmega328p at ~5.0v, through a 100 ohm limiting resistor and with a 10K pulldown to ground.  The SEPIC portion of the circuit is as follows:

The only difference being that my MOSFET is an STL260N3LLH6 and my diode is MBR2045EMFST1G - my LTSpice library doesn't have entries for the parts I am actually using.  The inductors are not coupled, and are rated for 48A current saturation.  All capacitors are ceramics.

At low duty cycles I am getting the expected behavior, although sometimes depending on inductor value and coupling capacitor value the output voltage is about 10% higher than it should be for a particular duty cycle.

Once I get to a duty cycle of about 55-60%, the voltage output no longer continues to increase and at about 65% the MOSFET gets extremely hot and will burn up if operated for too long.

Initially I thought I was not driving the MOSFET gate hard enough, as I tried to operate my MCU at 3.3v, but operating the MCU and MOSFET at 5.0v has not fixed the problem.  Inductor values from 1.5uH to 6.5uH have been swapped in with minimal changes to behavior as well.  I have tried coupling capacitors from 1uF all the way to 90uF, still no luck.  Switching frequencies from 400Hz to 128kHz have also been tried.

Can anyone point me in the right direction as to why my MOSFET is burning up?  For curiosity's sake, I built up a buck-boost converter using the same parts and got a similar result.


texts: What's causing my buck converter's switching node to oscillate only some of the time?

texts:
We got an order of 24 PCBs recently, and one of them doesn't work. I'm trying to track down the point of failure, and it seems to be our 3V regulator circuit:

At ~180ms intervals, the 3V output rail starts oscillating wildly, during which it drops below 2V and resets my microcontroller. It remains in this state for ~70ms, after which it returns to normal. Here's a scope capture. The green line is the 3V output and the yellow line is the switching node voltage:

During the failure event, the switching node voltage looks like this:

At other times, it looks perfectly normal:

I need to figure out what part is broken so we can rework the boards. My first guess is the IC itself -- the input voltage and enable signal look reasonable, the feedback lines up with the 3V rail, and the boost capacitor seems to be passing the output waveform, so what else is there? But I've never seen this behavior before, so I'd like to know if any other component failure could cause this.

(We have 30+ other boards working with this design, so I'm pretty sure it's a defect in a component or the assembly. I didn't see any bad solder joints.)


texts: How to properly connect an old record player output (spade connector, possibly amplified) to an RCA tape deck with built in amplifier?

texts:
I have an old magnavox record console which for some reason the speakers don't seem to get very loud.

Tracing the components, I think I can bypass those built in speakers completely and have the output of the system (spade connectors) go directly into an old tape deck with built in amplifier which has external speakers connected to it.

When using an adapter, anything to worry about?
How do I know if the signal is amplified?
Their is a volume knob but it doesn't seem to get very loud. A little less than halfway through turning does it finally start to make sound
The wires are connected to internal speakers and internal (I assume) things next to each speaker that I think does bass

The back of the console has the hookups for the internal speakers and hookups for external (all spade connectors screwed into terminals). The internal speakers just seem to share a single ground wire. Is that normal?

Doing a search on the internet for a bit, I couldn't find anything related to this specific model: 1RP621.


texts: Understanding type conversion in expression in vhdl

texts:
i've a source code where basically there's this expression:

unsigned( '1' & unsigned(((17-10-1) downto 0 => '0'))))

ncvhdl 93 returns

ncvhdl: 14.10-E460: (c) Copyright 1995-2015 Cadence Design Systems, Inc.
        unsigned( '1' & unsigned(((17-10-1) downto 0 => '0'))));
                                                           |

illegal type conversion operand [7.3.5].
        unsigned( '1' & unsigned(((17-10-1) downto 0 => '0'))));
                               |

can not make sense of P(...) [6.4] [6.5] [7.3.3] [7.3.5] 87[8.5] 93[8.6]

There's clearly a problem when i write expression like this... so basically i was wandering what's the return type of expression like:

(a downto b => c)?

I thought it was a std_logic_vector and in my mind the conversion to unsigned shouldn't give any problem...


texts:
As far as I know, a resistor and a heating element are the same thing.
But one, the resistor, seems to limit the current in the circuit
while the other, the heating element, draws more current and converts it to heat.

One wastes watts and the other doesn't, yet they are both resistors.

What is the difference between a resistor and a heating element?


texts: Easiest way to produce electric arcs from battery

texts: In a chemistry project I want to pursue, I need to temporarily ionize air, which I aim to achieve with a continuous electrical arc jumping across two wires. I am a true novice when it comes to electrical engineering, but I know for an arc to travel across the air one inch, it requires 1000 volts. A simple piezo igniter can do this momentarily, but how do you increase the voltage of a battery so it can do this same thing over a long period of time?


texts: ATX PSU turns itself off when uploading sketch to Arduino

texts:
I'm trying to power a stepper motor with the 5V rail of an ATX PSU and control it using arduino. To keep the PSU running, I have shorted the PS_ON pin to ground. Also, I have connected PSU ground to arduino ground. The arduino is powered over USB.

The problem I'm having is that the PSU turns off automatically when I upload a new sketch to arduino. I can reproduce the problem with these steps:

Turn on power (PSU is running fine)
Set one motor pin (e.g. digital pin 9) to HIGH
Upload a new sketch to arduino (doesn't matter which one, e.g. the Blink example)

-> PSU turns itself off.

Why does this this happen and what can I do to prevent it? The PSU seems to perform well otherwise.

simulate this circuit – Schematic created using CircuitLab

Edit: I just found these alternative steps to reproduce:

Power on
Set one motor pin to HIGH
Disconnect 5V rail of PSU from motor driver

-> PSU turns off

Further tests:

Disconnect motor from driver
Power on
Set one motor pin to HIGH
Upload new sketch

-> PSU stays on!

Connect motor to driver
Power on
Set one motor pin to HIGH
Disconnect motor from driver

-> PSU turns off

It seems to me that the PSU doesn't like losing load on 5V after it has seen load once.


texts:
I am software developer and I need to make cable to connect this http://lib.chipdip.ru/036/DOC001036112.pdf usb adapter (which I connect to USB port of my PC) to UART port of my A13 Olinuxino.

As I understand I must connect them this way:

UART(ADAPTER) : UART (A13)
ground(-) : ground(-)
plus(+) : plus(+)
RX  :  TX
TX  :  RX

Am I right?


texts: a Variable rehostate servo Motor to discharge a Tesla S model battery

texts: Anyone could help me to find a Variable rehostate with servo Motor to modify load on a high power system. I am trying to discharge a Tesla S model battery.


texts: Is the following op-amp-circuit-in-the-Laplace-domain analysis correct?

texts:
I am relatively new to analyze circuits in the Laplace domain.
So I decided to solve some problems as an exercise.

Below presented a problem and my solution to it and I have two questions:

    Once I have found Vout/Vin in the laplace domain. What is the actual gain. For example, suppose the input is a sine wave with amplitude 1V and frequency of 1kHz, How do I interpret the answer which is a function of s to an actual gain?
    Is my analysis of the transfer function correct? My main concern is that in equation (2) I considered only the resistance of C1 in (Vp - Vout), while the resistance of R2,C2 may also indirectly effect on this potential difference, since Op+ and hence Op- are effected from their resistances. Or, am I overthinking this?

Below The exercise and my solution.
Thanks!


texts: Overvoltage protection for AC relay dilemma

texts:
I am currently designing a safety-related device that has to open a relay when a certain event occurs. During most of its life, this relay will be closed, and only open if the safety event occurs, power goes out (the device will be installed in the US so unlikely) or the device needs servicing.

I am designing the "2.0" version and some of the circuits I am using have been taken from the previous version of the product.

One of those circuits is a MOC3083 zero crossing opto-isolated TRIAC drivers which drive a Z0103MN TRIAC in order to provide 110VAC to the relay coil, therefore turning this open/close.

The previously mentioned circuit is as follows:

Where R and Rg are both 330ohm.

From what I have read in the AN-3004 app note from On-Semi some sort of protection or damping is required in parallel with the TRIAC in the form of an RC snubber or MOV to avoid voltage spikes which can potentially cause the relay to close back or even destroy the TRIAC.

However, the previous design has already passed certifications and being sold in thousands without any RC snubber or MOV included.

Therefore my dilemma is the following: should I add an overvoltage protection element or shall I just follow the "if it's not broken don't fix it principle"?

In case I do have to place a protection device, will the MOV do the job given the fact that the relay will be most of the time closed? How do I calculate the energy dissipated on the MOV?

Consider that the relay coil has an inductance of 80H and it stays energized for most of its useful life.

Thanks!


texts: Calculating energy of transient/surge handled by metal oxide varistors (MOV) or surge suppressors?

texts:
As I get to know more about the MOV operation, there are more things needed to understand.

My MOV (V420La20AP) has Varistor voltage of 680 Vrms (10%) at 1 mA, and maximum clamping voltage of 1120 V at 50 A. Now my system (where this MOV is installed) generates a surge of 4 kV with timing 1.2/50 us. It has a source impedance of 2 ohm, so it has a short circuit current of 2 kA. I have this info, but I am not sure what would be the clamping voltage of MOV when this pulse is applied or what voltage it will output to the load. I found a formula for mov non-linear region which is

I = K * V_power(a).

Can this formula be used to find out about the clamping voltage at given current flowing throw mov. Then again what will be values of "K" and "a". They are dependent on MOV but manufacturer doesn't list these values.

Actually, I want to find energy of the surge handled by mov. According to SEMTECH,

E = E1+E2 = (0.5 * Vc * Ip * t_front_time) + (1.4 * Vc * Ip * t_50%time)

For this I need Vc (Clamping voltage at 2 kA peak current passing through MOV).

To know this, I need "K" and "a" , can I find these by simple mathematics applying 680 V (1 mA) and 1120 V (50), this way I will get two equation with two variables, and possibly I can find both of these values.

Am I doing it right? I mean this varistor equation (I=kV_power(a)) can be used this way to find any varistor voltage given current or vice versa?


texts: Conventional way to measure Li-Ion cell capacity?

texts:
I have an 18650 Li-Ion cell taken from an old powerbank, and was interested to find its capacity so I built a capacity tester. This consists of a meter (displaying volts, amps, and mAh), two 6V 5W lamps in parallel for a dummy load, and a TP4056 charger board with a DW01 on it to cut off the discharge current when the cell voltage falls to around 2.4V. I fully charged the cell then allowed it to discharge at just below 1A through the TP4056 board and lamps until (after about 15 mins) the lamps turned off. The meter showed a value of 315mAh. The cell then recovered back above the 2.9V over-discharge release threshold (and the lamps turned on again) only to fall below the over-discharge cutoff threshold (and the lamps turned off again). Allowing the setup to bounce around like this for 24hrs, the meter showed a value of 1,610mAh (with the cell still bouncing!)

The fact that the cell so rapidly discharges to cutoff at 315mAh out of at least 1,610mAh led me to conclude that the cutoff capacity of the cell will depend on the current being drawn from it. I tested this by removing one of the lamps and repeating the procedure. The current draw was just below 0.5A and (after something approaching 3 hours) the lamp turned off. The meter showed a value of 1,310mAh. (I assume that if it were left running again it would bounce around for at least another 300mAh.)

This leaves me unsure about how to measure the capacity of a Li-Ion cell. If it is the amount of charge released  up to the point where there is insufficient charge in the cell to recover back above the 2.9V over-discharge release threshold then I will never achieve that capacity in practise because the cell protection board will terminate the discharge prematurely. But if it is the amount of charge released up until the cell protection board terminates the discharge then the cell capacity would be dependent upon load resistance.

Can anybody tell me the conventional way to measure Li-Ion cell capacity please?


texts:
See the circuit below:

I am trying to make a shutdown circuit for a low power application. Basically, I want the system to be able to be turned on by a button push, and then turned off by a microcontroller. But I also want to be able to read the button state while the circuit is on.

In the circuit shown, when the circuit is off, the "E" input is high. This means that Q=D, which defaults to low when the button is not pressed. When the button is pressed, D (and consequently Q) go high, turning on the FET and enabling the circuit. This also brings "E" low, preserving this state.

Then, when it's time to turn off the circuit, the microcontroller pulls "E" low and turns everything off. It's important to note that the pin that "E" is connected to is normally a high impedance input.

My question is to what the state of "E" will be in the off state. This circuit is based on the assumption that "E" is high when the FET is off. However, I'm not 100% sure this is the case. My next step is to build this circuit, but I wanted to see if anyone could find something wrong before I buy the parts and try it out.

Thanks!

Part numbers:

D-latch: SN74LVC1G373DCKR

MOSFET: NTMFS4927NT1G

Battery: 18650 Li-ion battery


texts:
While thinking of ways to protect a MOSFET one idea was to put an extremely high resistance in front of the gate: The idea being that current is never supposed to flow through the gate, so if some transient threatened the gate, the resistance would limit that current, possibly preventing the FET from burning out.

In fact, while researching MOSFET protection I came across this integrally protected product that includes in its features "internal series gate resistance," as shown on its diagram:

If this idea is correct, then the question is: Why not always put a megaohm resistor before the gate of any FET?

Or is there a practical reason that a gate resistor would not typically protect the FET?  Or could it even have any adverse performance effects?


texts: I have a problem with ATmode in this module. I want to change baud rate and device's name, so I using an app Android "Bluetooth SPP" to pair with module and send ATcommand, but it doesnt reply when I send AT, then I test by connect TX to RX pin and it reply any character I send. In this document http://www.mcu-turkey.com/wp-content/uploads/2013/01/HC-Serial-Bluetooth-Products-201104.pdf , it said "before paired, it is at the AT mode", I misunderstand it, why we can send ATcommand while don't pair device???


texts: Using Timer 555 to obtain a frequency multiplier

texts: How can I use a timer 555 IC to obtain a frequency multiplier? I made a frequency divider by using a timer in monostable mode but a multiplier looked difficult. Can somebody tell how can I design a multiplier?


texts:
I understand that many components, such as electrolytic capacitors (Do electrolytic capacitors have a limited shelf life?), have a limited shelf life if not used. Other components, such as carbon resistors tend to change values over time while sitting on the shelf.

What I would like to know is if ICs also have a limited shelf life and if so, do some types suffer more than others?


texts: How do I connect an oscilloscope to a power supply or function gen.?

texts:
I'm supposed to sketch a circuit for my class but the one thing that has me completely confused is the ground connection.

For example: I have a breadboard with a 10V dc power supply and two resistors connected in series, and I want to measure the voltage across each individual resistor using an oscilloscope.

I know where to connect the signal clip thing, but not where to connect the clip that's supposed to go to ground, which is my main problem.

One of my teachers told me I can connect it directly after each resistor, another told me to connect all the ground clips to the end of the circuit (on the "-" side). My textbook just says in big red letters "CAREFUL NOT TO CAUSE A SHORT CIRCUIT".

Would the circuit be the same if I replace the power supply with a function gen or is there a difference?

I just don't get how grounding works and I've been reading more and more confusing guides online for 5h. I'm about to be graded on my work in 10h, haven't even slept yet. I'm sorry if I'm being confusing. Please help. Thank you.


texts: Can anyone tell me what this component is (goes to an AC motor)?

texts:
Does anyone know what this is? What do I replace it with?

This is from an old Wolf belt sander 5573 (which became the Makita 9401 I think) which was running, then just stopped. I checked the AC motor out (I think it's a universal motor) and it seemed OK.  This thing was pretty bulged and smelled when I tried it again.  It has the live and neutral as input directly from the switch and outputs three wires to the motor (the middle earth wire goes to the body of the stator).

Many thanks.


texts: Arduino is a microcontroller, so it won't help if you need complex tasks potentially involving standard hardware, like reading from an sd-card, or accessing ethernet/wifi. Is there a system-on-chip with the same amount of openness/documentation available ?


texts: How to sketch the Bode diagram of the output filter of a Buck converter?

texts:
I'm trying to figure out the Bode diagram of the output filter of a Buck converter:

simulate this circuit – Schematic created using CircuitLab

Vout is proportional to the current traversing the parallel impedance of the capacitor and resistor, Zrc, and the current is proportional to Vin and inversely proportional to the impedance of the inductance in series with the parallel of capacitor and resistor:

$$V_{out} = I \cdot Z_{RC} = \frac{V_{in}}{Z_L + Z_{RC}} \cdot Z_{RC}$$
$$Z_{rc} = \frac{1}{\frac{1}{Z_R} + \frac{1}{Z_R}}$$
$$V_{out} = \frac{V_{in}}{Z_L \cdot \left( \frac{1}{Z_C} + \frac{1}{Z_R} \right) + 1}$$

Replacing the impedance by their Laplace equivalents:
$$\frac{V_{out}}{V_{in}} = \frac{R}{s^2RLC + sL + R}$$

Which looks quite familiar (and confirmed by this application note, page 10)

Now, how do I continue to sketch the Bode diagram? I know I should identify the poles, but with my values, the poles are in the i plane:

L = 10µH
C = 100µF
R = 1Ω

Can someone give me a hint?


texts: Isolate microcontroller from board and use other one

texts:
The attached circuit block diagram shown in the rectangular box is my development board. It has microcontroller 1, which communicates with a SPI slave device (4 SPI line + 3 IO). 3.3V power goes to microcontroller 1 via a 0 ohm resistor.

Now I need to isolate this microcontroller 1 and make my slave device to communicate with the other microcontroller 2 . I do not want to cut tracks or remove microcontroller 1. So I think I can remove the 0 ohm resistor from microcontroller 1 section (see image). Now as per diagram I have two masters and one slave, but one master is not powered on, will this scheme work or not?


texts: Buck converter input/ output capacitance

texts:
For a typical Buck (Step down), synchronous converter please consider the given image:

I have added numbers there representing the following:

Input voltage
Input capacitance
Output Inductance
Output max current
Output capacitance
Output voltage
Switching frequency

My question is: Having the given requirements, i.e. Input and output voltage, max current, Output inductor value and switching frequency, how to calculate the needed Input and output capacitors values? The datasheet for a given converters provide some suggestions on what input/ output caps should be used for different cases, but they don't explain how can this be calculated in a universal way. I understand how different converters are built a bit differently, but the root idea behind them is the same.
How to calculate (estimate) input/ output caps values universally for a buck converter?


texts:
I'm trying to drive a speaker from an ESP8266 for a project, and found an article suggesting (ab)using I2S as a 1-bit Pulse Density Modulation DAC. Apparently that's pretty noisy, so the article gives the following circuit diagram for the low pass filter:

If I'm reading Wikipedia right, the 1KΩ resistor and 10nF capacitor to ground are a first order RC filter cutting off 16KHz. What does the 10µF polarised capacitor do?


texts: Power Path Controlling with GPIO and MOSFET

texts:
I'm not particularly well acquainted with MOSFET logic design and need some verification on a few things to make sure I've got them correct, and to see if there's any better ways of doing it. I need to control a 12v battery input terminal with a 3V3 logic level from an ARM microcontroller. I've put the following circuit together while digging through some other answers on stack exchange.

Power_Control is the ARM GPIO and operates on 3V3 logic. Q1 is an N channel Mosfet with datasheet. It has V_GS(th) = 2.1, V_GS being either 0, when the GPIO is low and 3.3 when it is high. So I assume that should work, but I honestly don't know if that's how I'm meant to be reading the datasheet. According to my understanding, Enhancement mode NFET should be off when V_GS = 0 and on when V_GS>=V_GS(th) and a Enhancement PFET should be off when V_GS=0 and on when V_GS<=-V_GS(th).

Q2 is a P channel Mosfet with datasheet. It's got max V_GS of +-20V so I assume it's rated to handle my input and it has a V_GS = -3V and it should either be -12 when Q1 is allowed to conduct or 0 when it isn't allowed to conduct. Q2 datasheet doesn't specify it, but I'm assuming it's an enhancement mode. Is that a correct assumption to be making?

Practically speaking, will this circuit work for the desired outcome? Are there better ways to achieve it? Less components, cheaper price or if it would be possible to use 2 of the same channel FET's as it'll save on cost.


texts: Reference ON/OFF voltage from microcontroller Raspberry Pi

texts:
I am looking for the simplest way to produce reference voltage ON=1.0V and OFF=0.0V from the Raspberry Pi.  I have learned that GPIO outputs are not very precise, and according to Exploring the 3.3V Power Rail, 5V power rail is also not very stable.  However the document suggests that 3.3V power rail is fairly stable, so I constructed this simple circuit:

Of course I would put voltage divider at the end to get the required 1V.

The required conditions are

at most 1% voltage drift,
output current can be small (to be supplied to another operator amplifier).

Does this circuit make sense?  Is 3.3V power rail stable enough for this purpose?  Can you propose another, not too complicated circuit, which would be even better?


texts:
In December 1947 Bardeen, Brattain and Shockey introduced a device which is considered to be the first transistor. This transistor was point-contact device. So, it used metal-semiconductor junctions.
According to book History of semiconductor engineering by Bo Lojek (2010), a principle of such transistor has never been fully understood:

...but as matter of fact, a good solid physical theory of point-contact transistor does not exist and even today we do not know, for example, why point-contact transistors occasionally exhibit negative resistance behavior.

As to produce point-contact transistor (or diode) is rather art (because each piece of semiconductor can have different impurities, damaged crystal grid etc. and it also depends where a metal contact is made), it seems obvious that each transistor could show different behavior (mentioned negative resistance, unstable gain etc.). These were reasons why Shockley worked out theory of P-N junctions and based on it introduced junction transistor which behavior is predictable.
I understand that point-contact transistor is now very obsolete device, however, I wonder if there is (or was) any research trying to understand point-contact transistors functions. Any information, paper etc. will be highly appreciated.
Cross-posted on SE.Physics


texts: The bottom row has an ETL Mark, a double insulate, an FCC logo, not quite sure what that little house next to the FCC logo is but what I am most intrigued about is the logo above them, it looks like VI.


texts: What are the long term effects of Organic Surface Protection (OSP) on PCBs?

texts:
I've just received a batch of assembled PCBs where the manufacturer changed the previously used HAL-process to OSP.

Now there is a lot of open copper on the pcb, like on big inductors which "suck" a lot of the solder paste to their leads. There also is a blank surface now which was never meant to be covered with solder paste but only with the Tin from the HAL-process to keep the area leveled.

Does anybody have a clue how that "open" copper might change in the future? Is the protection of the OSP still their after soldering or will the copper start to oxide now?


texts: A DC - DC converter that needs a constant high on the enable pin?

texts:
I'm trying to stabilize a battery output using a DC-DC converter. I got some Murata  ICs for testing (LXDC2HL and LXDC2HN). The datasheet gives an example of the circuit:

The EN pin confuses me. I need a DC-DC converter to get a stable power from the battery, but a prerequisite for it to work it needs an already stable 3.3V on the enabled pin. I'm failing to see the use case for this feature. Does this make the IC useless for a voltage regulation on an autonomous battery only powered circuit?


texts:
I want to use this ribbon connector (T812110A101CEU) with its corresponding PCB connector.

It is unclear if I should use the one with the short latch (T816110A1R101CEU) or the long latch (T816110A1S102CEU). Which is compatible?


texts:
When I was a kid, I built this circuit. You hook up a small capacitor to the test leads or maybe a couple in parallel and the speaker will output a different pitch based on the test capacitance. I thought it was a fun learning tool and I wanted to show it to my daughter.

The problem is, it seems these kinds of transformers are rarely used any more. I'd like to find a way to modernize the circuit to eliminate it. The one I used was a 4K CT : 2K

I don't understand center tapped transformers well enough, or I guess the circuit in general to do this myself. Hoping to get some pointers.

I'd be fine with using a black-box amplifier IC, the idea is to play with caps, amps can come later.


texts:
Is there any tool in linux that converts vhdl/verilog code to an equivalent schematic block.

I know the available tools
    * Synplicity
    * Synopsys Design Compiler
    * Altera Quartus II
    * Xilinx ISE

But these are not free.


texts: Maximum Input voltage of the DSO shell oscilloscope and TL084

texts:
In jyetech forum FAQ they mentioned that DSO shell is capable of measuring up to 50V directly:

  DSO Shell was designed for low voltage measurement. The maximum input
  voltage was specified as 50Vpk (peak value). So it can not be used to
  directly measure any voltage higher than 50V.

But by looking at the schematic:

We can see there's no division at U1D, 50V * 5.1M / (510K + 5.1M) = 45.455V. While the TL084 Input voltage is only 15V.

Am I missing something? What's the maximum input voltage for this scope?


texts:
I'm trying to control two servos at once using Arduino UNO and Arduino Motor Shield. My servos are modified, so that they can work with constant movement.

When I send the first order myservoP.write(180); (full speed) it works fine; however, when I try to order my servo to change direction (myservoP.write(0);), immediately my Arduino crashes and resets.

At first I though it may be a problem with the power supply, but after testing it with my program (listed below), I am starting to think that it's a problem with buffer or memory. Without delays, the Arduino crashes after about 10 iterations. With delay(10), it will crash after about 90 iterations. With delay(20), Arduino is able to repeat a full cycle 5 times, from start to finish. During the 6th attempt, it crashed again.

Here is my code:

#include <Servo.h>

Servo myservoL;
Servo myservoP;
int i;

void setup()
{
 delay(2000);
 myservoL.attach(9);   // attaches the servo on pin 9 to the servo object
 myservoP.attach(10);  // attaches the servo on pin 10 to the servo object
 Serial.begin(9600);
}
void loop()
{
  for(i=180; i>=0; i--)
  {
    delay(20);
    Serial.println(i);
    myservoP.write(i);
    myservoL.write(i);
  }
  for(i=0; i<=190; i++)
  {
    delay(20);
    Serial.println(i);
    myservoP.write(i);
    myservoL.write(i);
  }


texts: Screen of a mobile phone inside something

texts:
As an image for a speech I want to be able to shield of the coverage of a mobile phone. I thought of putting it in something. So I grabbed the stewing pan made of cast iron from the kitchen. Unfortunately it did not change the coverage the slightest. Is it possible to shield of the mobile from communicating with the cell towers in a simple way with things I'm likely to have at home or can by in my grocery store?

I could buy a lot of tinfoil and wind a really thick cylinder. But I'm not sure that would work. Not when my stewing pan seemed to make no change at all.


texts: A Strange Computer : Cache based computer

texts: In the Operating System class I heard from Professor that in some institute, researchers are working on cache based computer ( means the computer that don't have RAM and have a big cache ( probably 1 or 2 GB ) ). Now I want to know, is there anyone who knows some infornation about these computers ?if someone knows, please help me. thanks


texts: Matching IC drive capacitance with MOSFET input capacitance?

texts:
A quick and simple question:

  If I have a microcontroller pin that says that it "is designed to drive capacitive loads of up to 70 pF", does that mean that I can directly drive MOSFETs from the pin that have an input capacitance of 70 pF or less?

Obviously we are talking about low current logic level MOSFETs so that this is even remotely feasible, for example 2N7002K. Also it is obvious that the microcontroller can switch higher capacitance MOSFETs, just takes longer to do it, as long as current is limited so that the microcontroller is not damaged.

The key words here would be "designed" and "recommended operation". Under what circumstances would you recommend connecting a MOSFET to a microcontroller without a gate driver in between.


texts:
How much AWG do I need for my circuit wires knowing that the current can vary 10 to 20A with 12V supply

And what is the cheapest and safest way to join 2 wires together ?


texts: Altium Schematics: what does Locked function mean?

texts:
I am drawing a schematics in Altium Designer and faced this function when I double click on the components. I need to know when there is a component with different parts, ex: 4 parts. I have to assign the first part as Part 1/4 and the second part as 2/4 ... etc

Do I need to Enable the Locked function or not ? And what does it mean ?


texts: What happens when two digital circuits are connected and one is powered but not the other?

texts:
Assume the following, generic, configuration in which two digital circuits are interconnected but have independent power supplies (e.g. two redundant microcontrollers).

simulate this circuit – Schematic created using CircuitLab

Now, what happens if V1 is ON but V2 is OFF (or vice versa)? I generally protect against this scenario by inserting resistors on the lines such that the short circuit current is below the max sink current of the pins.

Is that necessary (perhaps something to look for in the datasheets?)? What would happen to the transistor level if no protection was included? Generally, enhancement mode MOSFETs are used, which means all switches are OFF (open) when no voltage is present, therefore I do not understand why there could be an issue.
Are there other means of protection? Those resistors prevent me from running communication lines at high frequency because of the time constant with the input capacitance.

This must be a question that has already been addressed but I can't seem to find any on SE.

Note that this question is only about protecting against unlikely or short events - both supplies will be ON for nominal operation.


texts: I wonder what is the name of USB ports like this. I'm searching for SBC with this kind of port but I can't find nowhere what's name of tips like that:


texts:
I am trying to analyze this circuit, the cap is initially charged to 3 V, the supply is 3 V. The NMOS threshold voltage is 0.7. Next the voltage at gate steps from 0V to 3V, what would be the voltage at source of MOS?

This is the circuit:

I am unable to understand the role of Cap  here, Could I consider it floating?

Thanks,


texts: Side effects of running an attiny13a directly on 9v

texts:
I'm doing a simple children's workshop in which they will build a small musical instrument on a breadboard with an attiny13a, ldr and a led. Right now it's powered by a 9v block and a regulator. Through some of the uncarefulness of the children, I discovered that the attiny13a seems to run just fine on 9v and the sound output is even louder! The regulator on the other hand gets hot, burning some children's fingers and is easily broken when the  children wire it up incorrectly.

I've been running a test of skipping the regulator and running the 9v directly into the attiny13a. This has been running for more then an hour without problem, it doesn't get warm at all, though the clock speed might have changed a bit, which is no problem for my purpose. As long as the chip keeps running for the duration of the workshop (an hour) plus some more. Even though it seems practical to just run on 9v, the attiny13a -is- only rated for up to 5.5v. What could be some unexpected side effects?


texts: Can I power a fan with a drill battery rather than a bunch of D batteries

texts: So I'm looking into buying a portable fan, most I've looked at run on D batteries (8) aka 12V. Now I don't feel like buying 8 D batteries every time I want to run this thing and I can't find rechargeable Ds (im sure they would be expensive). I was thinking however, I do have number of 18v drill batteries, is it feasible to fun the fan on off of those?


texts:
I have just bought my Arduino Uno rev3. I am really interested in Arduino.
For my first project I have to buy a breadboard and actually I did.I saw the schematic circuit in the book " beginning arduino programming " and I tried to make it .But I have a serious problem here . I am really interested in learning " breadboarding " . I mean I want to know how I can assemble a breadboard circuit from it's schematic and vice versa.
Are there any books , sites or resources that can help me by this?


texts: Why is there a rectifier diode connected to ground?

texts:
On the schematics for this DC/DC converter, there is a diode D2 which is placed between V+ and V-

On the actual board, the value for D2 is a M4 400V rectifier.

What's the purpose of this rectifier? It doesn't seem to be doing anything?


texts: Hardware debouncing of key matrix with minimum passive components

texts:
I have recently bought this cheap 4x4 keypad matrix. It only has the push-buttons and nothing else therefore I want to add a proper debouncing to it. The debouncing in software is something I want to avoid because it takes some processing power out of my application.

I know debouncing can be done using a resistor and capacitor (am I correct?) or schmit trigger (which requires another IC I guess and is out of question for me), so the question is, will I need to add R/C for each key, or can I get away with only one R/C pair per row or per column?

Any suggestions?


texts: Is it possible to create a Qsys system with VHDL generics at its top level?

texts:
Some components in my Qsys system have test modes. These are controlled via generics on their top level. These components are currently in a Qsys system.
In Qsys, I can click on them and change the generic value. The Qsys system is instantiated in a testbench and BFMs are connected to it. I want to be able to change their value from outside Qsys.

Is there a way to create generic at Qsys system level and then be able to change their value when the Qsys system is instantiated in my testbench? These "top level" generics will directly connect to generics on the Qsys system components' top level.


texts: How to diagnose eye diagram slope on physical impedance problems?

texts:
When looking at the eye diagram as shown bellow, if we have high rise time which is cause by RC properties, what can we say about the impedance? What could cause bad rise time?
Thanks.


texts: Powering multiple devices from a single power supply

texts:
I am learning electronics on my own and have been having a lot of fun. I am currently working on creating a Nerf sentry gun for fun with my son. I am at a point there where I need to power multiple devices and am not sure about the best way to go about it. I want to power a Raspberry Pi (RPi), two servos and a 12V relay that controls an air solenoid (12V). I bought a battery pack that supplies 12V and max of 3000 mA current. I am confused though on how to efficiently convert the power to each of the devices using the single battery pack.

I originally purchased a breadboard power connector that would convert 12V to to 5V on each of the rails. The problem I ran into was the breadboard power connector will max out at 700 mA and I cooked the first one when I hooked up my RPi.

Link to breadboard connector.

I also purchased some 5 volt regulators that seem to be most common but I run into the issue of wasting the excess voltage to heat. This also leaves me with the problem of how to split the voltage between two rails.

I guess my question is how can I take the 12V input from a battery pack and split it into 2x5V outputs to power each side of my bread board. My idea is that I want to power the two servos on one side and my RPi on the second from a single 12V input. I can create my own second battery pack to power the 12V relay outputs to control the air solenoid.

Sorry if my verbiage is not correct but I am trying trial by fire.

Extra links for the stuff I am trying to power in case I am completely off base:

2x servos
Relay to open solenoid
Battery Pack


texts: The best stack-up possible with a four-layer PCB?

texts:
I'm designing a 4 layer PCB and I know that the standard stack-up is

Signals
GND
VCC
Singals

(GND and VCC can be switched depending on the layer with more signals)
The problem is, I don't really want to connect all ground pins through vias, there are just too many of them ! maybe because I'm not used to 4 layer PCBs, anyway, I've read a tip by Henry W. Ott about a different stack-up

GND
Signals
Signals
GND

(Where the power is being routed with wide traces on the signal planes)
According to him, this is the best stack-up possible with a four-layer PCB, for the following reasons:
1.Signal layers are adjacent to ground planes.
2.Signal layers are tightly coupled (close) to their adjacent planes.
3.The ground planes can act as shields for the inner signal layers. (I think this requires stitching ??)
4.Multiple ground planes lower the ground (reference plane) impedance of the board and reduce the common-mode radiation. (don't really understand this one)
One problem is cross-talk, but I really don't have any signals in the third layer, so I don't think that corss-talk will be an issue with this stack-up,am I correct in my assumption ?
Note: The highest frequency is 48MHz, there's a wifi module on the board too.


texts: Non-led simple bicycle dynamo light system

texts:
There have already been questions about how to build a bike power supply based on the bikes dynamo.
Most of the answers contained lots of basic components. Some answers here are making a full wave rectifier from diodes.

I would like to keep the number of component minimal and use premade IC solutions. Lead by that thought, I came up with the circuit below.

simulate this circuit – Schematic created using CircuitLab

The goal is to have lights shining even when I'm not driving the bike. I reasoned at like this:

The AC source (dynamo) provides a voltage of 6V (6V/3W is usually found).
When the voltage level is high enough, the regulator is suppling 5 volts on it's OUT which is used to power up the lamps and battery if required. If the voltage is to small for the regulator, the laps are powered by the battery.

I believe that the battery might sometimes drain the power and make the lamps shine less bright, but that's ok given that in the original scenario they were connected directly to the AC source.

Am I missing some critical points with this circuit?

IC references:

http://www.engineersgarage.com/sites/default/files/7805.pdf
http://www.mouser.com/ds/2/149/DF06M-888822.pdf


texts:
I just got Pololu PGM03A programmer and ATMEGA328P-PU chip. The problem is that the programmer doesn't come with any 'case' where I can put the chip on so I'm guessing I have to wire it manually. I followed this guide:

Only difference is that I got 6 pin cable.

I double checked the wiring, exact match, but when I power up the programmer, the red LED is blinking, meaning it can't find the chip. I replaced the chip, but still the same thing happens.

I noticed that this person has extra power/ground connections to the chip:

Is this what I'm missing? can I safely connect it like this without burning it down? thanks!

UPDATE: I tried to connect the additional VCC and GROUND connections, but still nothing changes.


texts: Step-up converter generating too much voltage

texts:
I have the issue that I want to convert 5v DC to 12V DC.
I have several 5v to 12v step-up converter at my hands which all output around 15v without any load connected.
Now I heared these need a minimum load to get to their specified level, I tried to connect them to the circuit but still got around 14v.
Its just connected to a cheap 433MHz RF module that doesn't use much current.

What is the best way to increase my load a little to get to the desired 12v? The datasheet doesn't specify any specific current level.
Or can it even be a completey diffrent issue?

Datasheet: http://www.digchip.com/datasheets/parts/datasheet/194/SIM1-0512-SIL4-pdf.php


texts:
In the circuit provided by the link, would having an open secondary coil (not having it connected to any ground) damage the it?  The coil is connected to pulsed 240v ac at 50hz.  If it is not arcing, (meaning it has an open secondary coil) where will the electric field collapse, and will it damage anything?  Furthermore, if it can damage anything in the circuit, will it do so if it is under powered with a very low current?

https://www.instructables.com/id/Variable-voltage-ignition-coil-power-supply/


texts: Problem with adding two counters in series on an FPGA

texts:
I am using Verilog in Lattice Diamond IDE with a lattice MachXO2 7000HE breakout board.

I built a basic counter with a limit input which generates a variable period clock output. It works fine on its own, however, when I add two instances of this module and connect them in series (to scale the frequency twice), I get an odd result on the FPGA. The simulation, however seems to show what I had expected from the code.

Here is the top module:

 module clock_generator (fpga_clock, cnt1_clock, cnt2_clock, cnt2_counter);
    output  wire            fpga_clock;
    output  wire            cnt1_clock;
    output  wire            cnt2_clock;
    output  wire    [7:0]   cnt2_counter;

    reg     [7:0]   default_period_1    = 8'b00000011;
    reg     [7:0]   default_period_2    = 8'b00000011;

    defparam OSCH_inst.NOM_FREQ = "2.08";
    OSCH OSCH_inst(.STDBY(1'b0), .OSC(fpga_clock));

    counter Counter_1_inst(.clk_in(fpga_clock), .limit_in(default_period_1), .clk_out(cnt1_clock), .cnt_out());
    counter Counter_2_inst(.clk_in(cnt1_clock), .limit_in(default_period_1), .clk_out(cnt2_clock), .cnt_out(cnt2_counter));
endmodule

module counter (clk_in, limit_in, clk_out, cnt_out, rst);
    input   wire            clk_in;
    input   wire    [7:0]   limit_in;
    output  reg             clk_out     = 1'b1;
    output  reg     [7:0]   cnt_out     = 8'b00000000;
    input   wire            rst;

    always @(posedge clk_in or posedge rst) begin
        if (rst) begin
            clk_out <=0;
            cnt_out <=0;
        end else if (cnt_out == limit_in) begin
            clk_out <= !clk_out;
            cnt_out <= 0;
        end else begin
            cnt_out <= cnt_out + 1'b1;
        end
    end
endmodule

And here is the testbench for my simulation:

`timescale 1 ns / 1 ns

module testbench;
    wire            fpga_clock;
    wire            cnt1_clock;
    wire            cnt2_clock;
    wire    [7:0]   cnt2_counter;

    clock_generator dut(.fpga_clock(fpga_clock), .cnt1_clock(cnt1_clock), .cnt2_clock(cnt2_clock), .cnt2_counter(cnt2_counter));

    initial begin
        #1400000000
        $finish;
    end
endmodule

Here is the simulation output:

And the scope output:

ch1 - fpga_clock

ch2 - cnt1_clock

ch3 - cnt2_clock

ch4 - cnt2_counter[1]

And the probe setup:

Channel 3 (cnt2_clock) should have twice the period of cnt2_counter[1], as it is in the simulation output. Instead as you can see it's a burst of higher frequency edges where the single edge should be.
I've been on this for a while now. What am I missing?

Let me also add the shematic:

Thank you!

########## Edit with additional pictures

Scope output with cnt2_counter[0]

ch1 - fpga_clock

ch2 - cnt1_clock

ch3 - cnt2_counter[0]

ch4 - cnt2_counter[1]

[
And the probe setup:

Pin list


texts:
I've a design problem in VHDL with a serial adder.
The block diagram is taken from a book.

Since i'm not skilled enough in design with clock (except some silly flip flop i've found on the web, and similarly a register, where the design is pretty much the same) i have some problem in the design.

I would start with a register (n bit) a full adder and than a flip flop as basic component. Register and flip flop should be updated and shift for every clock cycle, the full adder is combinatorial so it is ok. I'm not sure however how the whole entity for the adder should be designed i would attempt with something like

entity adderSerial is
  generic(n : natural);
  port(x, y : in std_logic_vector(n - 1 downto 0);
       clk : in std_logic;
       z : out std_logic_vector(n - 1 downto 0));
end entity adderSerial;

The internal architecture confuse me a lot since actually i don't know how to behave in the synchronization stuff... At high level i would say probably internally should be even a counter that probably keep track of when all the bits are being processed. But i'm not sure if this is the right way to perform this design, i would like to keep as much close i can to the diagram i posted.

Any suggestion for such simple design?

Update...

Ok here i have my first attempt for the design... I splitted in three process, first process for handling the input registers, second for handling the full adder and third for handling the register z, i sync with a clock signal and i think i've written a correct sensitivity list for each process. Input signal are also clk, load and clear. Clk is the clock, load is to write the x,y value in the registers while clear is to clear registers and flip flop. Pleaaaaaaaaaase give me any feedback!!!

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_misc.all;
use ieee.numeric_std.all;

entity serialAdder is
    generic(n : natural := 4);
    port(x : in std_logic_vector(n - 1 downto 0);
         y : in std_logic_vector(n - 1 downto 0);
         clk : in std_logic;
         load : in std_logic;
         clr : in std_logic;
         z : out std_logic_vector(n - 1 downto 0));
end entity serialAdder;

architecture arch of serialAdder is
    signal x_reg : std_logic_vector(n - 1 downto 0);
    signal y_reg : std_logic_vector(n - 1 downto 0);
    signal z_reg : std_logic_vector(n - 1 downto 0);
    signal c_reg : std_logic;
begin
    process(clk) is --handling of registers "x" and "y", synchronous
    begin

        if rising_edge(clk) then
            if clr = '1' then --clear all the registers, and flip flop
                x_reg <= (others => '0');
                y_reg <= (others => '0');
                c_reg <= '0';
                z_reg <= (others => '0');
            elsif load = '1' then
                x_reg <= x;
                y_reg <= y;
            else --execute sum
                x_reg <= '0' & x_reg(n - 1 downto 1); --right input register shift
                y_reg <= '0' & y_reg(n - 1 downto 1);

                --full adder logic
                z_reg <= (x_reg(0) xor y_reg(0) xor c_reg) & z_reg(n - 1 downto 1); --right shift and adding a new bit
                c_reg <= (c_reg and x_reg(0)) or (c_reg and y_reg(0)) or (x_reg(0) and y_reg(0)); --carry update
            end if;
        end if;
    end process;

    z <= z_reg; --update of the output

end architecture arch;


texts: Checking if microchip or software is broken

texts:
I've build a circuit with a pic18F4550, I'm trying to power up 8 leds, but I get no output voltage from any output pin.

I suspect the pic might be broken because while building the circuit I made two mistakes:
- I wired the 5v regulator wrongly, and supplied 9v to the pic for the first time
- on one side of the pic I connected power to vss and ground to vcc

However, after noticing my mistakes and fixing them, I reprogrammed pic and got no error (I'm using MPlabX and PicKit2). Also the pic is not heating up or anything like that.

I triple checked all the wires and schematics, but there is only 5v in the two vcc pins, and 0v in the output ports.

This is my program:

#pragma config XINST = OFF
#if defined(__XC)
    #include <xc.h>        /* XC8 General Include File */
#elif defined(HI_TECH_C)
    #include <htc.h>       /* HiTech General Include File */
#elif defined(__18CXX)
    #include <p18cxxx.h>   /* C18 General Include File */
#endif
#if defined(__XC) || defined(HI_TECH_C)

#include <stdint.h>        /* For uint8_t definition */
#include <stdbool.h>       /* For true/false definition */

#endif
#define NO_CLRWDT
#define SYSCLK          20000000
#define PLL             4
#define SYSCLK_PLL      (SYSCLK*PLL)
#define FCY             (SYSCLK_PLL/2)

#include "system.h"        /* System funct/params, like osc/peripheral config */
#include "user.h"          /* User funct/params, such as InitApp */

void main(void){
    TRISD = 0x00;
    TRISC = 0x00;
    PORTC = 0xFF;
    PORTD = 0xFF;
    while(1){
    }
}

Could my pic be broken? and how can I check or debug the issue? I'm newbie at both soft and electronics.


texts: What percentage of losses occur in conversion from DC to AC?

texts:
I installed 4 solar panels on my roof each of 250 W. And a hybrid inverter (which the seller said can support up to 3000 W). I have got two 175 Ah batteries with it.

Things seemed to be working fine, until I recently found out that I could connect that inverter to the laptop via USB and check different readings.

When I did that, I was amazed to see that it was showing the current coming form the PV (solar panel) is about 550 W. This was when the sun was right in front of the panels. I called the guys who fitted it to see if one panel was dead or something, they checked, and turns out they are all giving 8 A each, so I thought there could be losses in the wire that is connecting the panels to the inverter, however, we checked the voltage right before the wire coming from the panels is plugged into the interver, and it was showing 32 A @ 32 V which is about 1000 W.

The issue is, the inverter still insists that the current coming from the PV is around 500 W.

If I put a load of about 700 W (by turning on all the fans and lights) it starts drawing current from the batteries.

Is this normal? Should I get the inverter checked? Here is the screenshot of the app that came with the inverter showing all the information.


texts: Won't get 5v on input of Arduino with power bank

texts:
I don't know why but i'm not getting 5v on the input of the Arduino, the only thing I've done is to add a switch in order to interrupt the circuit. Here it's my schematic:

I have another issue with the battery charger, I don't know why but in order to output tension it needs to be plugged to the main power supply (220v AC) so that it leaves the "stand by" mode. Is there any way to bypass this? Or how can I simulate this behavior without doing so? I'll leave a picture of the controller too.


texts:
I'm trying to fix a non-working device and the first thing I'm checking is the capacitors.
I desoldered the biggest one from the board as it seemed to have leaked a bit. It is a 330uF 16v capacitor.
I've tested it with the multimeter and I'm getting a reading of 285uF.
Does that mean it is bad? Or that reading would still be in range given the 330uF specification?
Thank you!


texts: How to calculate the Samples per second possible of a ADC (MAXIM 11605) using i2c with raspberry pi?

texts:
I would like to find out how many samples per second this ADC im using is capable of with a raspberry pi using i2c and python SMBUS2 library, but i dont know where to start.
As far as i know this depends on: CPU speed (how fast python runs), i2c speed, ADC sampling rate.
I would like my python program to return at least 10,000 values per second from the ADC.
Since the raspberry pi is running linux and the python program is a process with not all cpu power concentrated on it, it will be hard to determine how many times the pi can retrieve data from the ADC per second consistently. Example code of how many times python can increment a counter in 1 second:
import time
import smbus

cnt = 0
condition = True

ST = time.time()
ET = 0

while condition:
    if (time.time() > (ST + 1)):
        condition = False
        ET=time.time()
    cnt += 1

    #code for reading ADC potentially here: ADC_val = bus.read_byte_data(adr, Ain)

print(cnt)
print(ET-ST)

On my laptop with i5 @ 2.3 GHz it returned about 2.4 million times through the loop in 1 second.
The raspberry pi (actually im using a "vocore 2" a single board computer - similair to pi) returned 30k in 1 second.
The ADC (maxim MAX 11605 i2c version), supports i2c speed of 400kHz and 1.7MHz and is HS mode (1.7Mhz) it can do 188ksps and in FS mode (400kHz) it can do 44ksps.
So my question is, if CPU speed didnt matter, at an i2c speed of 400kHz of Pi and ADC and thus 44ksps from the datasheet, how many samples would the ADC deliver? 44ksps? Is the 400kHz relevant here?
Im grateful for any help or tips to find out more about i2c and ADC in general (and calculating sampling time),
thank you


texts:
Well, I have this circuit design that drives a motor (draws abt 3A) via N channel mosfet. It works fine on a breadboard. I decided to go with pcb and ordered some from oshpark. Suprisingly once the push button is clicked the mosfet turns on as expected but after letting go it never turns back off. First I thought there was something wrong with the button or the mosfet and replaced both of them but didnt do any good.

Does anyone know whats wrong with my circuit? I'm new to this pcb design thing and would love to hear your feedbacks.

MCU-> Attiny85

Mosfet --> PSMN1R0-30YLD

Power source --> 3.7 lipo 15A C rating battery

Thanks a lot!


texts:
I am looking for some kind of pin channel selector design for 16 signals, 0-5V. When a specific signal got high, I should get its number (address) over a 4 pins address. No simultaneous highs will occur.

I made an over simplification with 3 signals, and 2 address pins in the attached figure. I put three signals, and with the positive edge, I should recover the corresponding address -i.e. if the pin is the IN01, I should be able to get the "01" address through the OUT00 and OUT01 pins, and feed this into a uP for taking actions.

I could figure using RS latches for recovering the OUT00, but this procedure (could?) not be extensible at all for more signals and address pins. And surely with a single microprocessor accepting positive edging logic i could solve that straightfordwardly, but perhaps a uP could be too much for this.

Should I follow some Flip-Flop solution, or should discard them and seek for some digital programmable device?

Edit: The key functionality is called Priority Encoder, which can be implemented with a 74HC148, a delay line 2 Schmitt Trigger with \$R=10k\Omega\$, \$C=1uF\$, an additional Schmitt Trigger used as inverter, and an Universal Register 74HC194 used in parallel mode.


texts: The reason why the output of ZCS-controlled boost converter is 1.2V,not 1V in this paper

texts:
Here is the three stage  stepping up architecture,and in the paper,the author said that when \$ V_{out} \$ increase up to 1V,shunt connecting the capacitors  \$ C_{DDi} \$and \$ C_{out} ...Finally,the ZCS-controlled boost converter is gated and regulated by the on-chip reference circuitry, providing a 1.2-V regulated voltage at the output .

My question is when \$ V_{out} \$ up to 1V,\$ C_{DDi} \$and \$ C_{out} \$ will be shunt connected,then,why will the \$ V_{out} \$ = 1.2V in the end,not 1V?

Also,i want to make sure something,for the 1. mark in the first picture,it said  the internal voltage \$ V_{DDi} \$ is boosted with an enhanced charging current into  \$ C_{DDi} \$.Dose it mean that the \$ C_{DDi} \$ charge to boost the \$ V_{DDi} \$?

This paper is from the :ieeexplore.ieee.org/document/6484920/


texts: Devices with temporary push-on,push-off switches?

texts:
I have a couple of china-cheapie devices that seem to use some circuit with a single button where first push turns it on, second turns it off -- e.g. the button works as a toggle.

I would prefer to control these devices from an embedded device such as an arduino or a raspberry pi.

For example, one came with a small sample of smart-tint pdlc material that I would like to use as switchable frosted-glass on a small project:

smart tint glass sample ebay

EDIT begin: picture of the internals added.

Not a lot in this thing. And there wasn't a lot to see from the top.
The area around the black circle is the temporary push button switch.
The pins on the bottom left are the secondary (AC output) of a small transformer - you can see the primary pins of the transformer on either side of the 4.7u cap in the bottom middle.
Power in is on the left from two AA batteries (spring is -)
Indicator LED in the top right. (the switch, xfmr and led are all that stick out the other side that I can see - one sided PCB)
I'm guessing the two Y2 SMD are SS8550 PNP transistors. (google searches)

But after discovering they aren't very power tolerant (I let the magic smoke out of one of them) I'm now wondering if I shouldn't try to chase down a 5vdc to ac converter (this one seems to put out about 7vac at 500Hz, but another that came with a AC converter does 17vac at 60Hz)

I'd still be curious how to find and side-step the flip-flop part of the circuit though as I have other stuff like these that would be fun to power and switch digitally.

---Edit end---

Another is a 5v mist maker (ultrasonic piezo vaporizor). I have an alternate solution (Seeed makes a grove based one for this) but would still love to know if there's any easy way to replace their switching methods.

5v Mist Maker


texts: If I need to link two neighboring rows for a stripboard build is there any reason I should make a wire link over just placing a blob of solder between them? This is for a guitar pedal so the board will be jostled occasionally but will be in an enclosure the whole time.


texts: ESP8266 / ESP-01 - Customize the NonOS "at" firmware of SDK?

texts:
I am using an ESP-01 this way: MCU <-> UART <-> ESP-01, using AT firmware/NonOS on ESP-01.

I have my own encryption functions, and I would like to implement them both on MCU and ESP-01 sides at least for data packets, like those packets where ESP-01 send a data packet to the MCU starting with "+IPD" string, and also for the data that is sent from the MCU to the the ESP-01 after the MCU have sent the command AT+CIPSEND=n, being 'n' the quantity of data bytes to be sent.

Will I be able to to such modification on ESP-01 side? I mean, edit the NonOS "at"firmware? As I was looking, there is only few source files and much .a lib files in the folder of the SDK.

I want to do such encryption because my data is circulating unprotected between the ESP and the MCU. In my application, I use a SSL/TLS connection as internet client with the ESP with Google's Firebase database, but this way anyone could sniff my data by monitoring the UART signal. And to say, I am not able to use SSL/TLS (like mbedtls) inside the MCU because the MCU has limited flash memory size.

I already donwloaded the "ESP8266_NONOS_SDK-2.2.1", compiled it with virtual machine and did the download of the generated bins to the ESP-01, my question here is about the possibility to customize the "at" firmware.

Any suggestion for this case?

Regards,
Jeferson.


texts: Why are these similarly spec'd DC-DC converters an order of magnitude different in price?

texts: I need to drop ~12V to 5V, but I'll be pulling somewhere around 5-8A. Looking for DC-DC converters I found these (plus many even more expensive parts), but these model plane UBECs are a tenth of the price and appear to do the same thing. What's the difference?


texts:
I have a CAT 5 line with 12 DMX devices, each taking 4 channels.

I also have a CAT 5 line with 8 microcontrollers (ex. Arduinos). These controllers need to send back data, and require error detection.

Both chains have the same 8P8C layout. I would like to chain the two lines with the following communication rules:

1) 250,000 baud (for DMX512), 8N2

2) The master sends out DMX512 frames a minimum of once every second with the standard start byte (null)

3) When there is enough time to complete a communication, the master sends a SLIP encoded packet with CRC-CCITT integrity check. The packet includes an address that tells one of the controllers to respond with a SLIP encoded packet with CRC-CCITT integrity check. The communication is prefixed by an END byte to ensure interpretation as a new packet.

It is my understanding that since all of the SLIP packets would begin with 0xC0, the DMX devices will ignore them. The DMX devices would only accept data with the magic DMX incantation (break, mab, 0x00, ...).

Similarly, the microcontrollers would discard all of the DMX messages because they would not begin by issuing 0xC0, and if a 0xC0 is found in the message, the packet that follows would fail the corresponding integrity check.

What are the caveats to this approach? Do I misunderstand how DMX will handle the SLIP messages? Would it make more sense to have the microcontrollers implement RDM?

In case it isn't clear, I control all aspects of the master and the microcontrollers, but the DMX devices are off-the-shelf.


texts:
I've got NEC projector with broken switch with turns the projector off when lamp cover isn't in-place.

I simply cannot identify this switch. There are thousands of switches on online shops who specialize in selling electronic components.

What is the name or part number of such switch?


texts: Easiest and cheapest way to get digital outputs from a computer to the real world

texts:
I need a number of digital outputs to connect my computer to the real world, however it seems that this job is not nearly as easy as I had hoped.

I've looked into a number of different methods, ranging from dedicated digital I/O cards, micro controllers with USB interfaces, serial ports, parallel ports, ect. However all of the solutions seem to be either too expensive, too much work, or the technology is too dated.

I hope to have 64+ digital outputs running at approximately 1khz each, individually controllable. So far the best idea I can come up with is sticking the outputs of a serial port to an 8-bit serial to parallel shift register and sending chars down the serial connection whenever I wish to change and output (run from a USB to serial port adaptor). I haven't tested this yet so i don't know if it will work.

Is there any other quick and dirty method of getting a fairly large number of inexpensive digital outputs from the computer of which I can easy control with very basic C++ commands?


texts: How to disconnect a component with a microcontroller output?

texts:
I have a circuit that uses a PIC microcontroller and an OpenLog from Sparkfun (a microSD card logging module ).  Everything is running at 3.3V.

In order to conserve power when it is not in use, I want to be able to use a signal from the a PIC output pin to completely disconnect the OpenLog from power and ground when it is not in use.  Can someone provide some suggestions?

I have tried using a 2N7000 between the OpenLog and ground, but I think that the voltage drop across it is not allowing the OpenLog to get a high enough voltage to turn on.

The reason that I want to disconnect it completely is that there seems to be leakage current via the Rx and/or Tx pins if either the power or ground remain connected.

Do I need a solid state switch or something?  I would rather keep things inexpensive.  I am a bit of a novice and this seems like it should be simple, but I need help!


texts:
I am trying to create the formula for this layout but I have the feeling that I made a mistake.

The formula that I have at the moment is:

Can someone tell me if this is correct?


texts: Turn ON/OFF 5V 2-5A by Raspberry Pi GPIO

texts:
I need to control few 5V 2-5A devices by rpi GPIOs, which has the 3.3V logic level. I come up with a simple circuit, but I'll appreciate any ideas, corrections, suggestions. The LOAD is something like a powerful LED flashlight (pure real load, without reactive elements). It won't turn on/off often (once in a few minutes), so it shouldn't be a big problem with frequencies. All LOADs have common ground wire: they are parts of one device and all connected to the ground wire and chassis.

Is the circuit correct? Is it possible to improve it? MOSFET is 100V, is there any better choice?

UPDATE
After @brhans comment, I'm considering also Mosfet IRF9540 (it can work with 3A at 5V) or several FDN340P, but they are in SOT23 package (hard to assemble with my equipment). Is IRF9540 a better choice?


texts: Does the MPU9250 require a 53V3 level shifter when used with Arduino Uno?

texts:
this is a quick question.

I'm building a flight tracker which uses several breakout boards. Most of which operate a 3V3, hence they require level shifters to be able to work with the Arduino without damage.

However, no one is mentioning using a level shifter with the MPU9250 despite it working on 3V3. Robojax has even told me on his youtube channel that it is not required. How can this be?

But in the datasheet we see SDA and SCL are 0V to VDDIO (3v3)

Everyone is just connecting the breakout board like this

Can anyone justify the reason for this or disprove it?

Image of breakout board


texts:
I am designing an H-Bridge to control the direction a peltier cell that is connected to a variable-control current source. The current will be a maximum of 5A. The DIR1 and 2 are 3.3V from a micro.

The problem is that as the input voltage is decreased to < Vgs the P-type FETs will start to turn off.

I have access to +12V. I thought of using N-FETs on the top and driving with the 12V but then I have a similar problem when the input voltage is near 12V.

I was thinking of using a negative supply to drive the top FETs, would that work? Surely, there must be a simpler solution?

simulate this circuit – Schematic created using CircuitLab


texts:
I'm a newbie to STM32 coding and struggling with the following:

I used to code a little bit with STM32F103C8T6, using cubeMx and HAL libraries.
I made a code using the following code to set the pin to High:

   GPIOB->BRR = STEP_Pin;

It worked like a charm.

I just try to move my project to an STM32F446RE Nucleo.
I changed a few pieces of my code but I have a compiling error I can't get rid off.

../Src/main.c(175): error:  #136: struct "<unnamed>"  has no field "BRR"

I have this error for every single line using BRR.
Do you know what I should change?

Config: CubeMx, Keil, HAL Lib, STM32F446RE

Thank you