texts: Output different from input in unity-gain op-amp (voltage follower)

texts:
I am using an LM358p op-amp as a voltage follower (unity buffer).

I have a battery as a 9V voltage supply, two resistors for a voltage divider so that the non-inverting input of the op-amp gets 5.6 V. I checked this with a multimeter and it is correct.

The supply voltage to the op-amp (Vcc) is the same 9V from the same battery.

The output (Vout) is 2.9 V, whereas I would expect it to be 5.6 V (idealy) like the input.

Why is the output not he same as the input?

I then tried to replace the battery with a variable voltage supply. I can go to 13 V Vsupply, so that the non-inverting input goes to 8 V, but still see the output of the op-amp Vout is 2.9 V.

Am I doing something obviously wrong with my circuit?


texts: Is infrared photoemission from silicon used in IC manufacturing diagnostics?

texts:
In the video Why all solar panels are secretly LEDs (and all LEDs are secretly solar panels) a silicon photovoltaic cell from a calculator is purposefully damaged and then a 36 V bias is applied. When imaged with a normal silicon CCD (or CMOS) camera with its infrared filter removed, infrared light can be seen emitted from the photovoltaic cell and the damage visualized.

The pattern is well delineated and instantaneous as the voltage is turned on and off, and the device is hand-held so it's not thermal infrared; cutoff for a silicon CCD is 1.1 eV or about 1100 nm.

This sounds familiar to me. I remember hearing about the use of infrared imaging to localize defects or failures in ICs a long time ago, and I think it was explained to me that the radiation was direct emission from the silicon and not just blackbody thermal emission.

Question: Am I remembering correctly? Is direct infrared photoemission from silicon used in IC manufacturing diagnostics? If so, then since silicon is not a direct band gap material, how does it produce at least small amount of light?

Note: I was reminded of this when reading the recently-posted Physics SE question Do silicon solar cells act like an LED when you flip the voltage, or are we just seeing black body radiation?


texts:
I have been developing a control software for charging and discharging battery in a dc grid. The system consists of:

01) Three phase alternator with three phase diode bridge rectifier at its output and field current controller (nominal power of the alternator is \$P_{an}\$)

02) Load with variable power consumption (current power consumption of the load is \$P_l\$)

03) Bidirectional battery charger which works as a current source during charging and as a voltage source during discharging.

04) Li-Ion battery (power which is being currently charged or discharged is \$P_{bat}\$)

The main goals of the control software are:

01) determine the charging current of the battery and send this value into the battery charger

02) determine the output voltage of the battery charger during discharging and send this value into the battery charger

What I have been strugling with is how to determine the charging current and discharging voltage in a situation when I measure only the \$V_{veh\_bat}\$ and \$V_{dc\_bus}\$.

I have started with implementing a PID controller of the \$V_{dc\_bus}\$. This controller produces value of \$I_{charger}\$ at its output. In case \$I_{charger}>0\$ charging of the Li-Ion battery is requested and in case \$I_{charger}<0\$ discharging of the Li-Ion battery is requested. For discharging I am sending the reference \$V_{dc\_bus}\$ value as the discharging voltage for the battery charger.

This idea works only in case I don't allow \$I_{charger}<0\$ at the PID controller output i.e. only for charging. However the functionality is little bit doubtable because of the fact that the current for charging of the Li-Ion is drawn from the vehicle battery (which is being discharged due to this fact).

Does anybody have any suggestion how to solve it? Thanks in advance for any ideas.


texts: I found this symbol on the schematics of an FPGA board. AIN stand for Analog input.


texts: Producing negative to positive square wave pulse

texts:
Situation

I need 2 kHz -10/40 V square wave duty <1 % pulse to drive 50 ohm load.
I have a working 0-40 V solution: PWM by MCU driving a N-MOSFET low side switch off a 40 V DC rail.

simulate this circuit – Schematic created using CircuitLab
Questions:

Is it possible to somewhat shift the voltage to negative after MOSFET output (low side is tricky, no common ground)?
If not, what is the most practical way to produce such pulse?


texts: Clock source controlled by the logic that is being clocked by the source

texts:
What are the implications when an always block controls the switch that will change the clock source(actually more than one frequency coming from a clock divider) that is clocking the always block? How will the synthesis tool handle the timing? How should the constraints be given in such a case?

Example :

assign clk = (freq_val=='d0) ? clk_5M : (freq_val=='d1) ? clk_10M : clk_200M
always@(posedge clk) begin
   if(cond1) freq_val='d0;
   else if(cond2) freq_val<='d1;
   else freq_val<='d0;
end


texts: Need additional capacitor for comparator?

texts:
I am designing a circuit for interfacing the frequency input signal.
I used simple Op amp inverting comparator with hysteresis, as below

The op amp is single powered by GND and 5V.
Otherthan decoupling capacitor for the supply pin, is it necessary to add additional capacitors for signal conditioning?


texts: How do cheap phone chargers charge li-ion batteries?

texts:
I read about li-ion battery charging and it requires monitoring for the voltage and current, How does those extremely cheap phone chargers do that?
Or Is it just an adapter and the charging circuitry are embeded into the phone?


texts: CRC calculations by hand do not match online calculator

texts:
I have been trying to understand what is the trick behind online calculator which gives me CRC value for any input. The thing is that results I get with doing maths by hand do not match results this calculator gives me. On the other hand, I also found this calculator, which always gives the results I get by doing XORing by hand.
Also, I have done my calculations the same way they are done in the following sections at Wikipedia and here. I know I'm doing it the right way, however that calculator (and other ones, like this one) always gives me different results, except for some custom polynomials.
There might be a catch to the way these CRCs are calculated - Wikipedia suggests that there are next following polynomial representations: normal, reversed, reciprocal, reversed reciprocal. And first calculator I mentioned uses two more parameters regarding polynomial: initial value and final XOR value (for purposes of verifying by-hand calculations I chose CRCs with those two values being 0x0).
I'm really struggling to understand if I'm doing something wrong, where some sources say it's done this way, and some other calculators give completely different results then expected.
EDIT:
If the message and polynomial are of the same value, then resulting CRC value should be 0, since there is no remainder. This is how I checked that there is some other processes to CRC calculations other then the XORing message and polynomial:

On the other hand, I just found out that (at least) custom defined polynomials ignore the highest term of polynomial (in the case of CRC-8, this would be \$ x^8 \$ which corresponds to 9th bit). This can be verified by inputting message that equals real polynomial (addition of "1" to message byte):

This corresponds to the following quote from Wikipedia:

Omission of the high-order bit of the divisor polynomial: Since the high-order bit is always 1, and since an n-bit CRC must be defined by an (n + 1)-bit divisor which overflows an n-bit register, some writers assume that it is unnecessary to mention the divisor's high-order bit.


texts: Wire wrapping - how to attach a breakout board without soldering headers?

texts:
I intend to use wire wrapping for a project involving an Arduino, and a Time of Flight sensor (https://learn.adafruit.com/adafruit-vl6180x-time-of-flight-micro-lidar-distance-sensor-breakout/overview).

The sensor comes on a separate, headerless board, and the recommended approach is to solder a header to the board. I would like to avoid soldering a header, if possible.

My current thought would be to use a long pinned wire wrapping header, from underneath the breakout board, and wire wrap to it, but I am unsure if this approach will work correctly (I do not have the supplies to test it currently).

Is there recommended, non-soldering approach to attaching a headerless breakout board, using wire wrapping?


texts: I need help replacing a driver in my very underpowered 138w LED UFO grow light. i bought it for my son to grow chilli's and other consumables over winter months and also as something of a hobby. The crappy Chinese driver inside is universal voltage 100V-240V /50-60hz , output current 300mA, output voltage 80-130V DC. You see, when i ordered this thing it came as 138w 9-band UFO with 46x3w chips, so instinctively i though it should push 80-90 watts actual draw due to manufacturers habit of under-driving 3w LED's, but turns out it is a critically under-powered product that runs at only 42 actual watts, that's not even 1w per 3w chip and even less considering the fan itself consumes 10w, what we have is pretty pathetic intensity and a waste of 46 x 3w chips, it grows seedlings and small plants but is useless after that. I wish to replace the driver for something more powerful, I think its the low 300mA current that is the issue, driving them at 600mA or 700mA would push it towards 70-80w output so this is my issue the low constant current driving the 3w diodes. So anyway im wanting advice or guidance on what to do to get more bang for buck from this thing and i would appreciate either recommendations for alternative LED driver and/or other powering options.


texts: How to make a relay ON for few seconds after power goes OFF?

texts: I want to make relay circuit that can remain ON if power is supplied but as soon power is cut off i want the relay to go OFF after few seconds atleast 10 sec.


texts:
I am designing an antenna for a device and was hoping to gain some insight in the correct design direction for the antenna.

The Idea:
A receiver & antenna that fits in a 6" diameter by 3" deep cylinder.

Known:
Frequencies range from 162.400 to 162.550 MHz.
The signal will not be coming directly from the top or bottom.

Goals:
Design the “best” antenna I can given my knowledge of the direction the signal will be coming from, the size constraint of the enclosure and the frequency.

Any advice, recommendations, and/or help would be greatly appreciated. I am specifically interested in the physical layout/design of the antenna.(For example coil wire cylinder)

Thoughts: My gut feeling is to enclose the maximum area possible with the antenna. From my initial research the length is not as important as I had previously thought which lead me to start to ponder this even more.

Notes: I like math if you are so inclined :)

Additional questions answered:

Between 75 and 90 degrees and also between 0 and -90 degrees I dont
expect a signal in that region.
The environment for operation of the antenna is inside a home about
ceiling height(8-12 feet).
This antenna is intended for receive only.
It is feeding into a IC receiver.
Input impedance (50 ohms)
The signal is coming from miles away
The source is the NOAA weather radio all hazards broadcast
The frequency is not changeable


texts: I have a working motor taken from an old dryer. The motor plate says it runs on 120 V AC, but a separate housing on the motor for the connections indicates it runs on 240 V AC. When I opened the housing to investigate further, I am not quite sure how it works. Is there any way to get this to run on 120 V AC, and if there is, will it pull the 5.9 A the motor plate indicates?


texts: Why diffusions in CMOS CAD tool (Magic) is continuous

texts:
I am using Magic to draw some transistors and create digital logic gates. While I was studying the theory about MOSFET I've always seen images like the one below.

In this picture, one can see that below the gate, in the channel, there is substrate. In other words, the n-diffusion is not continuous. But when we are using Magic, the diffusion we draw is continuous as shown in the following image.

In Magic, the intersection between polysilicon and a diffusion generates a layer named ptransitor/ntransistor, but it is not clear to me if this represents a channel or not. So I've tried to export to GDSII and check if Magic would generate a hole/space/channel in order to split the diffusion, but even in the generated GDSII the n-diffusion seems to be continuous like the image below. I expected to see three boxes: first a diffusion, then the polysilicon and then another box, but in the GDSII there's only a rectangle that crosses the polysilicon, just like in Magic. I view the generated GDSII in gds3d and KLayout.

What I want to know is the time that the channel is generated. I can understand that in Magic we draw the diffusion crossing the polysilicon as this helps in speeding the drawing and also may help the algorithm for circuit extraction. But I can't understand why there is no channel in the generated GDSII, which is supposed to be the file that we send to the foundry for fabrication. Does the foundry process the GDSII and generate the channel, or is the channel already in the GDSII and I am not seeing it?


texts: is there a difference between these 3 diodes?

texts:
http://www.mouser.fr/Search/Refine.aspx?Keyword=1N5819-E3/73

1N5819-E3/73
1N5819-E3/53
1N5819-E3/54

the first one is 4x cheaper than the last, why ?

aren't they all the same ?


texts: Converting 3 seperate 4.5V battery operated devices to one AC power supply

texts:
I'm wanting to convert 3 battery operated marquee signs to AC power by following one of the many tutorials out there on sites like instructables.com.  I'm more than capable of doing each one on its own and having 3 wall warts for each sign.  My question is can I power all 3 signs off 1 AC power supply?  Each sign takes 3 C batteries so I know to do each one would require a 4.5v power supply on its own.  Could I do 1 13.5v power supply and wire it to all 3 signs?

Thank you.


texts: How to determine brushless DC (BLDC) winding pattern, based on poles and slots?

texts: I am trying to figure out how to determine the correct winding pattern for a 3-phase BLDC motor, given that there are 10 poles and 18 slots. I have seen the very interesting post here., but as the 10-pole 18-slot pattern has not been confirmed, I am wondering how these patterns were devised in the first place.


texts: Would anyone care to provide a simple explanation about the interaction between an audio signal and a DC bias current in regards to voltage/current calculations? For instance, an audio signal with 1v peak to peak interacts with a transistor base voltage divider at 3v. I am new to audio signal calculations. Does the positive waveform voltage (and current I assume) add to the DC bias and negative waveform subtract? Forgive me if I'm completely wrong. Trying to get a mental model before I delve into complex equations. Thanks for any help.


texts: starting material for silicon production

texts:
Where does silicon semiconductor manufacturing start from? I mean, what are the principal ores that may be used to start the technological process and what extraction process is used? (And what are the principal countries that extract such ores?)
I know that quartz sand is a common raw material for this process, but I do not manage to understand how it is obtained. In the industrial practice, is it taken from the beach, desert, or from inshore quarries? Or perhaps blocks of quartz minerals are extracted and then turned into sand by a mechanical process.
The staring material for

Yoo's Semiconductor Manufacturing Technology is high-quality sand
Quirk's Semiconductor Manufacturing Technology is pure sand
Geng's Semiconductor Manufacturing Handbook is quartz of quartzite
In May's Fundamentals of Semiconductor Manufacturing and Process Control I was unable to find a word about it.

Any suggestion about books containing more information about that subject is highly appreciated.


texts: auto-recalibration of a power supply through something stable over time? (thought experiment)

texts:
Highly accurate instruments with a calibration are quite expensive, and anything electronic will tend to change over time.  The effects of heat and oxidation, and perhaps changes in the material due to current directly.  Perhaps there are other reasons circuits change over time.

So I was wondering about some kind of reference that could be built into equipment so it could recalibrate itself.  Suppose you wanted to have a fixed power supply that would stay stable at a precise voltage or at least be capable of re-calibration without sending it for expensive recalibration at the factory.

Thinking about what kind of components could be stable, I think a wire-wound resistor with thick connectors and soldered connections.  Zener diodes would seem less stable.

So can anyone suggest a way to build a circuit that would provide an extremely stable voltage reference? Given such a voltage reference, I think it would be possible to build an extremely stable power supply.

This question is mostly theoretical out of interest. I'm not asking for a practical design at this point though I wouldn't say no!


texts:
I am designing a system which has a lot of wires. These pass power, communications (RS422), ethernet and even analogue video (NTSC,PAL). Now, these wires meander all over the place. One of the wires was an SPI wire that was about 25-30 cm long and was sending a clock of approx 8MHz or so. Now, the communication was failing quite often.

Now, I reduced the length to about 4 cm and the system worked well. So, I would like to do an analysis on the wire lengths in my system and its impact. How can I do that?
Also are there any simulation tools or papers that can help me proceed in this ?


texts:
Trying to figure out the timer setup in Atmel Studio 6 for an ATmega16 microcontroller.  And I just don't get it.  I am trying to create a TickCount similar to GetTickCount() Retrieves the number of milliseconds that have elapsed since the system was started, up to 49.7 days.

Code looks like this:

#define F_CPU 8000000UL                         // 8MHz - prevents default 1MHz
// *** timer code necessary for handling lost coms, use volatile when variable is accessed from interrupts
volatile unsigned long TickCountSys;            // Number of milliseconds that have elapsed since the system was started.
volatile unsigned long TickCountComs;           // TickCountForLastComs
volatile unsigned long TCNT0_overflow_count = 0;

ISR(USART_RXC_vect) {
    TickCountComs = TickCountSys;               // Milliseconds since system started when received something.
    //blah blah
}

void timer_init() {
    TIMSK=(1<<TOIE0);                           // Enable timer overflow interrupt for timer0
    TCNT0=0x00;                                 // Set timer0 counter initial value to 0
    TCCR0 = (1<<CS00);                          // Start timer0 without prescaler
}

ISR(TIMER0_OVF_vect) {
    TickCountSys++;
}

int main(void) {
    timer_init();
    DDRC = 0xff;                                // Set all pins on PORTC for output
    sei();
    unsigned long TickCountENQ;                 // Tick count for sending enquiry character, 05dec, ^E
    char coms = 0;
    char ignore_coms = 0;
    while(1) {
        coms = (TickCountSys < TickCountComs + 50);
        if (TickCountSys > TickCountENQ + 25) {
            TickCountENQ = TickCountSys;
            // If not ignore coms, that is need coms, and has coms, i.e. has not lost coms, then send new Enquiry char every 25 ms
            // It stops asking for coms if coms is lost, and does nothing until new command received and then starts syncing again
            if (!ignore_coms && coms) USARTWriteChar(0x05);
        }
        if (!coms && !ignore_coms) {            // If not coms and not ignoring lost coms then stop all movement
            PORTC = 0x00;
        }
        //blah blah...
    }
}

Tools-->Device Programming-->Fuses says:

BODLEVEL    4V0
SUT_CKSEL   EXTMEDFXTALRES_16KCK_64MS

As far as I know this is the correct settings (was delivered that way).
There is just something I do not understand by reading the timer tutorials.

EDIT: What do I do so that the TickCountSys increases once every milllisecond and gives the number of milliseconds that have elapsed since the system was started?


texts: Arduino NANOs sharing input signals and controlling Pixel Ring blowing up

texts:
We're a bit stuck on the following problem :

We've connected a bunch (18 to be precise) of Arduino NANOs on the same +12V supply and they all share the same PWM output from another device (which goes into an input of each Arduino) and also a boolean signal in the form of a +5V (12V going through a voltage divider).

Problem is: On the bench with two units, it works perfectly fine. But when we put all of the 18 units in parallel in the system, the Arduinos start to fry one after the other (about 8 so far and usually 2 or 3 at a time).

The µC gets real hot and lets out the magic smoke. The regulator itself is completely OK and doesn't heat up significantly.

We don't see where we might be wrong. I completely agree that inputs should be buffered, protected and whatnot, but for a prototype we really thought that'd work... But that's not the case!

simulate this circuit – Schematic created using CircuitLab

Thanks for your help!


texts: Microcontroller acting as USB host for an audio device

texts:
Are there any microcontrollers which are able to act as a USB host for audio devices?
Basically I'd like to create an interface which allows my to connect my USB headset to the analog microphone/headphone jacks of my PC (so it doesn't appear as a separate sound device to the OS).

However, I have no idea if cheap microcontrollers are powerful for that or if there are any microcontrollers which support usb-audio.
Googling wasn't very helpful; most controllers supporting usb-host only support mass storage devices...


texts:
My university resources say that DMA transfers the bunch of data from IO unit to memory or vice verse when processor is not busy with data and address bus. According to the resources, DMA Controller needs these two system bus for data transfer, and it cannot perform data transfer when they are used by processor.

Up to now, It makes sense.

My university resources also says that DMA transfers the data in some instruction cycle steps in which processor does not use data and address bus. For example, an instruction cycle consists of 4 steps:

1) Instruction Fetch
2) Instruction Decode
3) Operand Fetch
4) Execution

DMA transfers the data when processor works in Instruction Decode or Execution, since CPU will not use address and data bus. In this point, I am confused.

Modern processors utilize instruction pipeline. In other words, the instructions are not executed sequentially. When command 2 is in "instruction decode" section, command 3 is in "instruction fetch". The instructions follow themselves without any gap. In this case, there will be always an instruction in the step "Instruction Fetch" or "Operand Fetch". Namely, data bus and address will be always used. DMA cannot find a chance to benefit from these bus lines for data transfer. Instruction pipeline does not allow DMA to be used.

How and when is DMA used ?
I explained my confusion below. Is there anyone who can explain this ?
My university resources are wrong or there is a trick that I cannot figure out ?


texts:
On a 10MHz ATTiny10, the following code generates the same 40kHz 50% duty PWM on both pins 0 and 1:

DDRB = (1 << PB0) | (1 << PB1); //Output on PB0 and PB1
TCCR0A = (1 << COM0A0) | (1 << COM0B0); //Toggle OC0A and OC0B on compare match
TCCR0B = (1 << CS00) | (1 << WGM02); //Clear on compare, use unscaled clock
OCR0A = (1000000L /40000 / 2) - 1; //Overflow twice per 40kHz period
OCR0B = (1000000L /40000 / 2) - 1; //Overflow twice per 40kHz period

I want pin 1 to be exactly inverted: both pins should be PWM 40kHz 50% duty, but inverted of each other. How can I achieve that?


texts:
I understand what decoupling is needed, but I did not understand how it is applied.

For example, in this scheme that I found, there are many capacitors at the output. (Is a DC-DC converter).

Some cap are unpolarized, and other polarized. The total capacity seems to be 680uF.

However, I did not understand if decoupling occurs only if the capacitors are installed in the way the producer done the scheme, or that is only the minimum capacity, and a greater capacity is always better.


texts: Any possibility of electric spark with my multimeter with the circuit?

texts:
As I understand voltage of the circuits could be different in absolute term, so that's one of the reason we make the ground.
One of my fear about working with circuit, especially when I use multimeter with the circuit power on, is that my multimeter probe makes electric spark with the circuit. I am not sure if I am paranoid or using my multimeter in a wrong way. But in my mind my multimeter uses 9V battery and the circuit uses whatever power regardless grounded or not. Then, because these are two different power system, isn't there some possibility of electrical spark on the moment that I approach the circuit with the circuit?
Probably if I measure between the ground of circuit and the point in the circuit that would be mostly okay as I can think my multimeter and the circuit is common grounded. But what if the points in the middle of the circuit? Should I attach my probes first before powering on the circuit?
I know it doesn't happen so easily and multimeter also has different specifications(+safety circuit inside) depending model. But I'd like to know more properly so I can avoid any accident or frying my components.
FYI, my multimeter model is UNI-T UT61E.


texts: What can I do to decrease the latency from these serial ports which are attached to a PC via a Serial to USB adapter?

texts:
I think I have accidentally discovered a need in my life for embedded systems. Which is great! And kind of scary. And I need help.

Background: I got hired to build a GUI application which takes scans from two SICK LMS-291s and integrates them with a sub-inch accuracy GPS, so you know where each scan occurred. As the naive web programmer I am, I understood that timing would be important, but didn't realize it would also be hard! If you don't know when each GPS point and each scan occurred, you can't figure out where the scans occur. Oops.

They had specified windows 7 as the platform, as well as bought a SeaLevel RS422 to USB box to hook up the sensors and GPS to, and in short order I discovered my folly. Somewhere between the sensors and my computer program, something was keeping the scans from arriving in a timely manner. The LMS spits out 75 scans per second, or at 13.32 ms/scan. My program doesn't get them in a timely manner. It gets them every 100 or so milliseconds, in groups of 7 or 8 or 10 or something. Also sometimes not enough scans show up, or they're mangled. Either this SeaPort adapter is only sending ten times a second (is that possible? I don't know how USB works) or Windows isn't checking the buffer (there must be a buffer somewhere, right?) nearly often enough.

Present Day: This leads to some inaccuracies that the client is basically okay with. I'm not, though, and since I've got a chance to do similar work for the client (integrating more sensors inputs!), I'd like to figure out how to do it right, e.g. given the accuracy of the GPS, be able to give guarantees about the precision and accuracy of the scan locations.

What does that look like? I need a UI, and to be able to check input from these three devices every 13.32 milliseconds.
If I used FreeRTOS with, say, Nano-X for the GUI, run on a laptop they provide, would that sound like a sane solution? Is it possible that the RS-422 to USB adapter is causing these delays, and using Windows is actually just fine for this purpose?


texts: 5V I/O Chip Which Works Like An Atmel µC Port?

texts:
I'm working on a project with a 5V vintage 8-bit microprocessor, which I would like to hook some I/O to.  I'd like to find a nice little package that could help me with this.  I'm happy if it is a modern chip.

It would need:

Per pin input / output selection
Input pull-up resistors built in and selectable
Output capable of driving at least 50ma

Does such a chip exist?


texts:
Some ICs have their pins labelled only with numerical values and some use alphanumeric labels. I want to know what is the correct naming term for these cases.

Is it ok to call all the chips with alphanumeric labels BGA (ball grid array)?  And for chips with only numeric pin labels the chip should be called DIL (dual in line)?


texts: 3.3V Buck-boost converter outputting voltage too high

texts:
I'm using a buck-boost converter RT6150B with fixed 3V3 output. I followed their application notes, and here's my circuit setup:

Note: I used 22uF for C4 intead of the recommended 20uF for output capacitor. I couldn't find a good SM component for 20uF and I thought 22uF is close enough.

Testing condition: I made a small test PCB based on this schematic, and I used a external power supply to feed different input voltage levels into the IC. From Vin = 3.1V-4.2V, Vout was kept pretty stable around 3.9V (Iout~20mA), which is too high comparing to the expected 3V3 output. When I try lower Vin = 3V, Vout dropped significantly to around 1.7V (Iout~140mA).I can also hear very small buzzing sound from the IC when I was testing with it.

There are several issues here, but first of all I don't get why the output voltage is around 3.9V instead of 3.3V? I used the recommended inductor value from the datasheet for generating 3V3 at output. Other things are just capacitors to decrease the voltage ripples. I really don't know what is causing this issue.

Any help is appreciated!

[Update]
Here's the screenshot for Vout:

(Sorry for the bad quality. Had to take the picture with my phone...)


texts: RCA cable with plastic pin - what's its purpose?

texts:
I noticed that my computer was playing sound out of only one speaker. The speakers are connected with a 3.5mm => 2*RCA cable, and when I inspected it, I found that the right RCA plug's inner pin was plastic (picture below). I replaced the cable with a regular cable, and now both speakers have sound.

The cable says Microlab on it, so it probably came with the speakers themselves (Microlab FC-330), though I'm not positive about that.

My question: What is the purpose of this kind of cable? Why would it be shipped with speakers?


texts: In a grid of resistors, does placement of the voltage source affect the nodal resistances?

texts:
Does the placement of the voltage source affect resistances in nodes in a grid of resistors?

And if yes, then is there a right way to "generally" analyze the resistances between nodes of such circuit? I.e. without the analysis depending on the voltage source's place, but rather only on the resistors (and location of nodes) themselves. Can one e.g. analyze the resistances of equivalent resistance without considering any particular voltage source?

A more simple example:

In this circuit, does the resistance between A and B depend on whether you put the voltage source to come in at A and leave at B?

Some methods for solving these problems are given here:
http://www.rfcafe.com/miscellany/factoids/kirts-cogitations-256.htm


texts: 12V to 3V voltage regulator for sensor implementation, cost & power efficiency

texts:
I am trying to design a system for a sap flow sensor with a heated needle in a tree. This particular sensor has a heater resistor of 50 ohms, and the application calls for a 3V input and ~0.2 W power.

I am also using a data logger that requires a 12V input to log the sensor output. I can connect the 12V battery to the logger no problem, but I am trying to find the right way to handle the 12V to 3V conversion from the 12V battery (we're using batteries like these and will be replaced and recharged as necessary)

I am starting to understand that a voltage regulator may be the right avenue, but I do not have experience building or buying these. The manufacturer that sells the sensors also can supply us with voltage regulators, but these are $500. These seem really expensive and beyond the scope of our budget. After a quick google search I see already-built voltage regulators that are less than 5-10% this price. What gives? Am I missing something here?

I am also learning that these voltage regulators release heat based on the voltage drop and supplied current and some are more efficient than others. The sensor/needle will need to be constantly heated (i.e. supplied the above 3V) for ~18 hours each day and will not receive power for the remaining hours at night. These sensors will ideally be continuously logging for weeks to months and left in a forest. I will be monitoring these sensors periodically, but not every day. I don't really know how to evaluate purchasing or building cheaper voltage regulators for my application. I just want to be sure nothing get super hot or melts(?) for the duration of our research project.

Does anyone have any suggestions how best to tackle my problem? For me, it is as much a technical problem as it is a budgetary problem. We require 10 set ups, so 10 voltage regulators at $500 each is too much for us to justify before looking into other options (e.g. other sensors, other research questions, etc).

Please let me know if any other information not in here would be useful.

Thank you!


texts: Addition and subtraction in digital electronics

texts: Why is it that addition of the 2's complement is an efficient method of subtracting? Does this simplify the circuit?


texts: Why do phasors work with s-domain transfer functions?

texts:
In as few words as possible, here is my question:

Why can we get the output phasor by multiplying the input phasor by the s-domain transfer function evaluated at the (complex?) frequency we're dealing with?

An example will serve to better explain:

simulate this circuit – Schematic created using CircuitLab

(Note: I am tacitly ignoring the initial conditions; for now I want to simplify the problem and only consider the steady-state response)

$$H(s)=\frac{V_C}{V_{in}}=\frac{1/(sC)}{sL+R+1/(sC)}=\frac{\frac 1{LC}}{s^2+s\frac R L +\frac 1{LC}}$$

If we wanted \$V_C\$ as a phasor, we would simply perform

$$V_C = V_{in}\cdot H(j2\pi \cdot1000)=3\angle45˚\cdot \frac{\frac 1{LC}}{-4\pi^2 \cdot 1000^2+j2\pi \cdot 1000\frac R L +\frac 1{LC}}$$

This would result in some complex number, which we would interpret as representing a sinusoid in the time domain. (Note: Already I'm confused... the input voltage waveform is not a complex number in the s-domain; it's actually some function of s).

I can understand how phasors arise naturally when solving DEs in the time domain; you assume your output is of the form \$Ae^{j2\pi ft + \phi}\$ and the time-dependence cancels out in the equation. I can also understand that multiplying by the transfer function in the s-domain produces the correct output in the time domain (provided the system is LTI). I can even understand why Ohm's Law, KVL, and KCL work in the s-domain.

However, after all that I can't get my head around this "abuse of notation". Phasors and s-domain expressions shouldn't have any business hanging around each other! So what am I missing here?


texts: Does current flow in/inside an ideal AC voltage source/generator like it flows in an ideal electrochemical battery? How does the process happen?


texts: NAND gate LVS problems in Cadence Virtuoso

texts:
I don't know why my layout won't pass LVS. I am constructing a NAND gate, and it looks like I have all connections in the schematic and layout fine, but I can't get it to say success. What could be wrong?

1


texts: Calculating Energy Consumption Using a Current Sensor and Voltage Sensor

texts:
I'm creating a PCBA that uses a hall-effect sensor to measure current and a transformer rectifier design to measure the mains voltage.  The voltage is 110-240 V, ~60 Hz. I wrote a digital filter and average the current every 1 based on 120 samples per second, taking the maximum and minimum values to get the Vpp of the waveform.

I then use I(A) * V(V) = P(W)
I do that calculation every second and store it in an array.
I then created a timer function that counts seconds, minutes and hours.
But I seem to be getting errors in my Wh calculation.
I want to sum up total energy used for a period of time, like how long the washer or dryer runs for.

So my equation is P(Wh) = Watts(avg/minute) * (minutes-sense-current-started/60)
The idea seems simple, but my total energy keeps jumping around.

Timer Function:

void mesure_time_pased(int status){
    if(status == 1){
        if (millis() >= (previousTime))
        {
            previousTime = previousTime + 1000;
            seconds = seconds +1;
            if (seconds == 60)
            {
                seconds = 0;
                minutes = minutes +1;
            }
            if (minutes == 60)
            {
                minutes = 0;
                hours_1 = hours_1 +1;
            }
            if (hours_1 == 13)
            {
                hours_1 = 1;
            }
        // Serial.print (hours_1, DEC);
        // Serial.print (":");
        // Serial.print (minutes,DEC);
        // Serial.print (":");
        // Serial.println(seconds,DEC);
        } // end 1 second
    }else if (status == 0) {
       seconds = 0;
       minutes = 0;
       hours_1 = 0;
    }
}

I then use this logic to calculate the energy - is there a better way to do this?

if( charge_status == 200 && relay_status == 1){
        if(millis() > data_collection_time + DATA_COLLECT_INTERVAL){
        data_collection_time = millis();
        uint32_t timestamp = Time.now();
        currentValue = asc711_digital_filer(CURRENT_SENSSOR_INPUT);
            if(currentValue <= 0)
            {
                currentValue = 0.00;
            }
        watt_energy = mains_voltage * currentValue ;
        if(watt_energy >= 0){
            total_watt_hours = (watt_energy * hours_1) + (watt_energy + (minutes/60)) + (watt_energy + (seconds/3600)) ;
        }
        op_amp_adc_in = analogRead(CURRENT_SENSSOR_INPUT);
        pcb_temp = NTCS0805E3103JMT_thermistorReading(THERMISTOR_ONE);
        relay_temp = PT103J2_thermistorReading(THERMISTOR_TWO);
        LM95071_temp =  SPI_Sensor.getTemperature();
        sensor_data = String::format( "{ \"sessionid\":\"%s\",  \"timestamp\":%u, \"current\":%0.2f, \"voltage\":%i, \"watts\":%0.2f, \"totalwattshours\":%0.2f, \"temppcb\":%0.2f, \"temprelay\":%0.2f, \"lm95071temp\":%.02f }", strsessionid, timestamp, currentValue, mains_voltage, watt_energy, total_watt_hours, pcb_temp, relay_temp, LM95071_temp);
        charge_session_data_blob.concat(sensor_data);
        // Serial.println(sensor_data);
        }
        if(millis() > time_send_data + INTERVAL_SEND_DATA_TO_CLOUD)
        {
            time_send_data = millis();
            Particle.publish("charge_session_data_blob", sensor_data , PRIVATE, WITH_ACK);
            charge_session_data_blob = "";
        }
}

I would love to create something more efficient at tracking time and totaling the energy used. I'm open to new ideas as I've tried a few and this is the best I've come to and I'm still not happy with it.

Thanks again for the help.


texts: How to measure 2.5 volts out of 5 volts and serial resistors?

texts:
I have a circuit that's being run from a 5v and is essentially a series of resistors. I want to be able to "tap" it to get 2.5v - 3v out of it, which I think would be straightforward, but I want to do this at the end of the circuit.

Specifically, I have a raspberry PI 5v output that goes through a resettable fuse (PPTC), then some heating coils (Kanthal wire) of various resistances, and then to a MOSFET drain. In total, the resistance is about 30 ohms. Source is connected to ground, and the Gate is controlled by the GPIO output of a Pi. This works fine.

However, I'm concerned that something might happen, like blowing out the fuse, and I want to monitor that it's working properly. To do this I was planning on connecting the circuit to a raspberry Pi GPIO input checking that the pin goes high when I turn on the circuit (via the MOSFET).

Simply, how do I connect this? I'd like this check to encompass as much of the circuit as possible. By that I mean that I only want to get the signal on the input if the PPTC and the wires are "working".

Since the 5v is not switched by the MOSFET I can't really tap that to check that the circuit is working. Notwithstanding the that, I considered taping after the PPTC and then using a voltage divider, but that would only confirm that the PPTC is working, and wouldn't confirm the heating elements. I considered tapping after the last heating wire and before the MOSFET, but at that point the voltage measures close to 0v, which wouldn't drive the GPIO input.

Two ideas:

Connect right before the MOSFET Drain. Also connect to the 3.3v line through a large resistor to pull up the pin. Then when the MOSFET opens up and the circuit is properly working then the /tap/ should get pulled to ground because it's close to 0v at that point.
Set a transistor right before the MOSFET Drain that can be driven with the small voltage that will exist there, then let the output pull up the pin.

Edit:

This is the schematic:

The two variable resistors (R1 and R2) are the heating wires, and are about 15 ohms each, but do vary.


texts: Read / Write an acceleration sensor (ADXL345) with STM8

texts:
i bought a small board with an acceleration sensor (ADXL345) on it and now i try to write my functions to communicate with the IC. I use an STM8S103F3P6 as controller and ST Visual Develop as IDE. So at first i took a look at the "rising/falling edge schematic":

So at first i want to write the "writeCommand" function, it looks like this, currently:

void writeCommand(uint16_t cmd){
    uint8_t i,k;
    GPIOD->ODR |= (1<<SDIO); //turn SDIO HIGH to turn it LOW later

    GPIOD->ODR &= ~(1<<CS); //turn CS LOW
    delay_ms(2);
    GPIOD->ODR &= ~(1<<SCLK); //turn SCLK LOW

    for(k = 0; k < 2; k++){ //proceed with toggling R/W and multiple-byte bit
        GPIOD->ODR ^= (1<<SDIO);
        delay_ms(1);
        GPIOD->ODR |= (1<<SCLK);
        delay_ms(1);
        GPIOD->ODR &= ~(1<<SCLK);
    }

    for(i = 0; i < 15; i++){ //start writing data
        if(cmd & 128){
            GPIOD->ODR |= (1<<SDIO);
        } else {
            GPIOD->ODR &= ~(1<<SDIO);
        }
        GPIOD->ODR |= (1<<SCLK);
        cmd << 1;
        GPIOD->ODR &= ~(1<<SCLK);
    }
    delay_ms(1);
    GPIOD->ODR |= (1<<CS);
}

I am wondering why there are only 6 (A5...A0) address bits? I am not sure how to concatenate the register i want to write to and the data.

Would this be the right way to call my function?

writeCommand(0x2C << 8 | 0x09); //write 1001 to 0x2C register

I know that it is probably possible to do this with hardware SPI but i want to learn how to do it by software.
So maybe a few questions sound retarded but i hope you will still answer them :)


texts: Could unwanted magnetism be part of my soldering problem?

texts: First off, I'm already resigned to the fact that I am a failure at soldering. (hours of research into dozens of website/youtube how-tos, 4 different soldering irons (albeit inexpensive), 9 or 10 different tips, fluctuating flux amounts, 3 different brands of solder, innumerable attempted techniques, 2 or 3 permanent tiny scars from sub-dermal blistering, and a small pile of charred electronics had, some months ago, broken my will and led to my surrender). But I'm still left with an unproven theory that others here might help confirm or reject. Being that, when faced with being placed onto a targeted location, the solder--after assuming a spherical shape--would, at times, refuse to separate from the iron's tip or, more often, flee the area, rolling the length of the workspace, around obstacles, up walls, or--I imagine--down entire city blocks until I would decide to break off the chase and simply create a whole new obstinate silvery blob, could it be that I had inadvertently magnetized the soldering tip by storing it next to a battery or some other atmospheric anomaly and thereby causing it to disrupt the normal soldering process and ultimately revealing it to be the cause of my circuitrous disability? While I eagerly await your replies I will click on the "unwanted magnetic induction" question to the right that I just now discovered. My gratitude to the team, --smf


texts: Ways of devices to communicate to other devices wirelessly

texts:
I am a programmer and I am trying to figure out a way to get information from wireless devices to gather information from for example I have a device(toy car) I would like to get information(speed, distance it run, etc and the information is available on the vehicle) from it.

  "What are the ways to get wireless information from the device? and
  possibly the resource?"

Please note it's all still under development so I have nothing concrete. Sorry if the question is vague it's pretty hard for me to explain since this is not my profession(just willing to learn).


texts: Magnetic vector potential and displacement current

texts:
I'm reviewing some EM theory and I've come across something that doesn't make sense to me. My textbook states that the magnetic vector potential is defined such that \$ \textbf{B}=\nabla\times\textbf{A}\$. Then it goes on to derive \$ \textbf{A}=\int\frac{\mu\textbf{J}}{4\pi R}dV\$ using the Biot-Savart law, which (as far as I'm aware) allows one to find \$ \textbf{B}\$ given any dc current distribution (no displacement current). Then the book 'fixes' \$ \textbf{E}=-\nabla V\$ so that this equation is valid for time-varying fields: \$ \textbf{E}=-\nabla V-\frac{\partial\textbf{A}}{\partial t}\$, where \$ V=\int\frac{\rho_v}{4\pi\epsilon R}dV\$. So we've got four equations: $$ V(t)=\int\frac{\rho_v(t')}{4\pi\epsilon R}dV$$ $$ \textbf{A}(t)=\int\frac{\mu\textbf{J}(t')}{4\pi R}dV$$ $$ \textbf{E}=-\nabla V-\frac{\partial\textbf{A}}{\partial t}$$ $$ \textbf{B}=\nabla\times\textbf{A}$$
The book states that, given a (potentially time-varying) charge and current distribution, the scalar electric and vector magnetic potentials can be found and then the electric and magnetic fields can be found from these potentials (taking into account retarded time). Now \$ \textbf{E}\$ makes sense to me, since it depends on both the charge distribution (through \$ V\$) and the magnetic field (through \$ \textbf{A}\$).
But how is it that \$ \textbf{B}\$ does not depend on displacement current in these equations? Is it the case that \$ \textbf{J}\$ ought to be interpreted as the total current distribution, including the displacement current? I don't think so because later in the book it uses \$ \textbf{A}\$ to determine the fields around an antenna and only the free current density in the antenna is included in \$ \textbf{J}\$.


texts: I have 2 12v batteries wired in series to get 24v. Can I add the third battery to one of the other two in parallell?

texts:
Is this something that is possible? Is it a good idea? I would then have double the amp hours on one "set" of the batteries in series.
All batteries are the same brand and type.


texts:
I have a vehicle which I have upgraded the AV electronics from a newer model (infiniti G37).  To do this, I created an adapter harness that effectively moves the wiring to the new locations.  The wiring harness includes a CAN BUS pair of wires.  The adapter harness is approximately 7 inches in length.  At the time of doing this, I did not have enough knowledge of CAN bus to know that I needed twisted pair.

I developed an issue while driving, where the one component that uses the CAN BUS wiring became completely unresponsive (Climate Control).  After shutting the car off for a few hours, the system became responsive again.  this has happened a few times now, but is inconsistent as to when it occurs.

It's possible that I just have a loose wire, and will be double checking that, but given that the AV unit's internal system diagnostic software won't let me select the Climate Control system to diagnose when the issue occurs makes me think that I have an issue with the CAN BUS.  Once the system is back to working, the diagnostics of the climate control system work fine.

My question... would not having twisted pair in the for the adapter cause enough error to cause the system to become this unstable?

I do plan to address the issue immediately but mostly wanted to understand the effects.


texts: How do I find the power factor and the equivalent inductivity value for this given scheme?

texts:
My exam is in 2 days and I just can't figure this thing out. I have the following scheme:

First I was asked to find out the impedance, resistance and reactance of the dipole given below. This is what I found out:

Z = 40 + j7 [Ohm]
R = 40 [Ohm]
X = +7 [Ohm].

Now I need to find out the equivalent value of inductivity for this whole scheme. I know that for parallel circuits the equivalent inductivity value Le is:

Le = ∑1/Lk = 1/L1 + 1/L2 + ... 1/Ln

and for the series circuits the Le value is:

Le = ∑Lk = L1 + L2 + ... +Ln.

How should I apply this formulas for this given scheme?

For the power factor, this is what I know:

kp = P/S.

I thought of replacing the P with RI^2 and the S with ZI^2, but I don't know how to get the Z value out of that complex value I found out earlier for Z.


texts: half bridge IGBT not switching high side on

texts:
I have designed a PCB with a FAN73933 half bridge driver. It is designed to drive 2 IGBTs (FGH40N60SMD) with +- 170V rails. I have attached a schematic for better understanding. The problem is I can not seem to get the high side to turn on. The system uses a boot strapping method to boost the gate voltage for the high side.

When I scope the boot capacitor I see a steady ~12V, which is my Vcc for testing. My rail voltage is +12 and 0V so all my GND,COM,-V are tied together. I'm driving the system with a simple Arduino for testing, its outputting a 1khz 50% duty wave with ~10% dead time, this was verified on a scope. The low side gate driving wave form is as expected and I believe the low side is turning full on.

The high side seems to never have any voltage on the gate. That being said, as i crank up the frequency above ~20khz I begin to pull a lot of power. I'm using a 50 Ohm test load so the max current draw should be ~ .5A I'm seeing ~6A based on a shunt resistor.

What I don't understand is that there appears to never be any gate voltage so i cant be having a shoot through. Also the controller has shoot through prevention, it will not turn both gates on at once. I'm really confused, all the signals look OK except for the bootstrap and the high side gate.

The boot diode is a 600V Schottky also.
One item to note is when I start pulling a lot of power the high side IGBT will get warm.

Any input would be appreciated.


texts: Video Standard White Levels, RS-170 or RS-343

texts:
I have a customer defining some equipment which outputs analogue video. They have said it would be to NTSC RS-170A standard Y C (on a S-Video, Mini Din connector), however I'm not sure if they really mean RS-343A.

The difference being RS-170 is 1V blank to white, and RS-343A being 0.714V blank to white which I always thought was the common video levels. Sync is -0.3V in both cases.

Has anyone got any idea what the standard video levels would be. I assume they would be the same for Y C / S-Video as for composite.

I have tested a cheap COTS video capture device and this only accepts 0.7V, further making me think my customer really means RS-343A. Before I question it with them I'd like to get a feel for what you guys think. I don't believe they would want to output video levels not commonly commercially supoorted.


texts: I have the need to monitor a remote facility using  8 x CCTV and an intrusion alarm. I would like to use a cloud based software to manage this system. This site has no 3G or 4G coverage however we have a good signal 2km away. Does anyone know if the kit exists so that I can transmit the data from our racks on site over RF and then link to the 4G system? Thanks


texts: Breadboard ATmega328P@internal8MHz upload verification fails

texts:
I have a breadboard set-up with an ATmega328P running with the internal oscillator at 8MHz (3v3).

I have burned the following fuses: H=0xDA, L=0xE2 and E=0xFF

I am using external power and USBtinyISP (6-pin ISP, with jumper off) to set fuses and upload.

I have the usual caps between every pair of power connections for the mega.

I can set fuses with no problems, but when I try to upload a program verification fails unless I set fuses first. That means that the upload procedure is 1. set fuses and 2. upload.

When upload fails, it reads the fuses and they are correct as given above.

This is a minor annoyance, but I am afraid that it is an indication that something is wrong with my circuit (or something else?).

I initially set fuses with an external 8MHz crystal connected.

Anyone familiar with same or similar problem?

EDIT:
After a successful upload, I can repeat successful uploads if I do not change the code.

I tried to clean and rebuild without changing the code and it still succeeds. I then tried changing some code and hit upload (with implicit rebuild) and then it failed!

I then tried to add a comment, which should not affect the resulting binary and it succeeds as well.

Thus, it seems to be related to code changes that affects the binary to be uploaded (which makes kind of sense).

Best regards,
Anders


texts: Tool, algorithm or method to know which resistors to use for an equivalent resistance \$R_T\$?

texts:
Say I have to get a resistance \$R_{T}\$ and I have a bunch of resistors, \$R_1, R_2, \ldots, R_n\$.

Does there exist a tool, algorithm, or method that gets the resistance value closest to \$R_T\$ by connecting (one or more) of the resistors \$R_1, R_2, \ldots, R_n\$ in series, in parallel or a combination of those two? And how to connect those resistors to get that value? So not trial and error. :)

Thanks in advance.


texts:
I'm new to embedded systems so apologies if this is a stupid question.

I am trying to implement a binary counter in the form of 8 LEDs. I want to send an 8-bit binary number through USART and have the 8 LEDs display the number (led off if bit is 0, led on when bit is 1).

What would be the best method to do this?


texts: Can reconfigurable antennas be used at base-stations and cellphone towers? I read that MIMO antennas are used at base-stations for 4G systems (and will be used for 5G). Are these antennas reconfigurable?


texts: How can I set a delay in Verilog using a clock?

texts:
I'm trying to write an always block that will open a valve and then keep it open for a few seconds and then close it if needed. The valve opens when the input is 1 and it closes when it's zero. How can I make the code wait for a few seconds after the valve opens so that it doesn't close right after it opens?

Here is my code:

input in, alteraclock;
output reg out;
reg clock;

clock myclock(.clkin(alteraclock), .clkout(clock));

always@(in)
begin

if(in==1)

begin
out=1;  //open valve

end

else
begin
out=0;  //close valve
end

end

PS: I'm using an Altera DE2-115, if that helps at all.


texts: Why have my MOSFET drivers blown in this H-Bridge?

texts:
I've built a discrete H-Bridge circuit to run a reasonably beefy 12V windscreen wiper motor. The circuit is below (EDIT: see here for a bigger PDF, StackExchange doesn't seem to let you expand the image):
RM: See larger imgur image here - these are saved by the system but only displayed at small size. Also accessible via "open image in new tab"

Bringing the board up, I started with 100% duty-cycle (non-PWM) mode, and found it functional, so I began PWMing one of the low-side N-channel MOSFETs. This also seemed fine, although caused noticeable heating in the high-side schottky on the PWM'ed side of the bridge from the inductive spike.

I then began PWMing the high- and low-side MOSFETs in an effort to dissipate the inductive spikes more efficiently. This, too (with what was probably an excessive amount of dead-time), appeared to be functioning fine, with the top-side diode staying cool.

However, after running it for a while using a switch to vary the duty cycle live, I dropped the speed from approx. 95% duty cycle to 25%, something I had done several times before. However on this occasion, there was a pop and sudden high current draw, and the TC4428A MOSFET drivers had blown.

These were the only components that blew—the MOSFETs themselves are fine, so I'm ruling out any shoot-through muppetry on my part. My best explanation so far is an excessive amount of either inductive kickback, or (more likely) too much regenerative power from the motor slowing for the power supply to deal with. The TC4428A has the lowest voltage rating within the bridge (18V, absolute max 22V), and I'm thinking the voltage has risen too high too quickly.

I was running the 12V side of this board off a old-fashioned linear bench-top power supply, with relatively long leads between it and the board. I imagine this wasn't really capable of dissipating the voltage rise.

I don't think the TC4428As were overloaded in terms of the MOSFETs' dynamic load; I was PWMing at a relatively low speed (around 2.2kHz), and the MOSFETs themselves don't have a particularly high total gate charge. They seemed to stay cool during operation, and besides, A and B drivers blew, despite only driver B being PWMed.

Does my hypothesis seem reasonable? Is there anywhere else I should be looking? If so, is the liberal sprinkling of a some beefy TVS diodes around the board (on power supply input and between the bridge output terminals) a reasonable way to deal with the over-voltage condition? I'm not sure I want to move to a switched braking-resistor type setup (it's only a “little” 2.5A-or-so 12V gear motor...).

Update:

I've placed a 1500W TVS across the 12V supply terminals (an SMCJ16A); this seems to be clamping the over-voltage during braking to just under 20V (this shows the supply voltage; an identical waveform is seen between the MOSFET gates and 0V):

It's not pretty, and it's probably still too high (clamping voltage of the SMCJ16A is 26V at max current—57A, whilst our TC4428A absolute max is 22V). I've ordered some SMCJ13CAs and will place one across the supply, and one across the motor terminals. I rather fear that even with a beefy 1.5kW TVS it's not going to last; you can see that it appears to be clamping for a good 80ms or so, which is a long period for a TVS. That said, it seems to be staying cool. Of course with actual load on the shaft... perhaps I may be implementing a switched braking resistor solution after all.


texts:
I am looking into electrolysis efficiency using an auto-locking PLL circuit that is supposed to latch onto the resonant frequency of the electrolysis cell, a frequency determined by the inductance of the bifilar coil and the capacitance of the cell containing distilled water.
To that end I have acquired a circuit for which I have assembled and built a PCB design (attached) and, to help me understand how it works have also drawn up a flow chart (attached) showing the logic of its operation.
So far I have been unable to get the PLL to lock and so I wanted to check that the circuit is correct based on the functional diagram of the HEF4046B chip (also attached). In reading the datasheet and how the PLL works, it uses two types of comparator and I think my circuit is using comparator 1 and yet the output of comparator 2 (Pin 13) is also used.
My query is, whether this circuit is right to do the job.
For example, I was wondering if instead of PLL output Pin 13 being fed back to its Pin 9, via the NOR gates and Switch, Pin 1 should be instead?
I hope this is not too complicated a question but to someone familiar with this type of chip and circuit I think it will make sense.
Thanks


texts:
I want to extend the use of a camera. The camera currently uses a special li-ion 3.7V 1000 mAh battery. I could grab a couple of those batteries, wire them up in parallel, and that'd work just fine. But if I didn't want to use those special batteries, would there be any problem using standard batteries? For example, could I wire up three AA 1.2V 2400mAh bats in serial to end up with a 3.6V 2400 mAh battery?

Now my real question: Is the voltage difference (3.6V versus 3.7V) a problem, or is it close enough?

Thanks.


texts: MIPS invert - why are the 2 operands always inverted first thing?

texts:
I'm learning about MIPS 32 bit.

I understand that CMOS technology uses NAND and NOR for the AND and OR commands, but still, I don't understand why is the inverter at the begining. Another thing is that part that has a 1 on it (in the picture right before the inverter or as part of it) - what's its job? why are there 0 and 1 on the bitinvert?

I know how an inverter is implemented in CMOS, are we talking about that inverter here?

What do the 0,1 and 2 in the ALUMUX mean? Does the ALUMUX decide which of the results gets passed forward according to the current instructions?

Thanks a lot!


texts:
I am new to STM32 and recently trying to make a custom board with STM32F103RB. But I am a bit confused by the available methods to program the chip. Let's say I use ST-Link via SWD, does it mean that I do not need to burn bootloader to the chip on my own? That is, does it mean that I can program the brand new chip directly with ST-Link without any other additional procedure?

If yes, then does it mean that I do not need to use BOOT0 and BOOT1 pins?

What about using USB via USBDP and USBDM pins on STM32?

Thank you all very much!


texts: AT89S52 microcontroller only starts when extra 22uF capacitor touches board

texts:
I made simple code for the microcontroller that prints a simple message on the LCD once the microcontroller starts. I arranged my board so that the pull-up resistors and reset resistor (100K) and capacitor (0.1uF) goes inside the DIP socket and I included a 0.1uF decoupling capacitor there as well.

Due to the PCB design, I added jumper wires with ferrite beads on them from regulated +5VDC to the micro's VCC.

I also went crazy with capacitors. I used one 470uF decoupling electrolytic capacitor as the main power reservoir and near that I added a 0.047uF capacitor.

I made the power planes as large as possible and labelled them on the board as + and -.

The crystal is 20Mhz with 33pF pull-down capacitors.

Everytime I attempt to start the microcontroller normally, no code is executed (I get indeterminite output), and the LCD is never initialized.

However, everytime I temporarily add a 22uF capacitor and hold it to the power planes under the microcontroller  while powering up the circuit, the code gets executed and the correct message is on the display. So then I soldered the 22uF capacitor in the same spot, tried powering everything normally, and I get nothing.

Is there something my fingers are doing to make the circuit work? (static or something?) This really baffles me.

And would my problem be eliminated if I cut the crystal speed in half?


texts: What does "number represented by the 5-tuple" mean?

texts:
As in from homework problem:

  Plot this function in K-map:

  \$F(A,B,C,D,E)\$ is 1 if the number represented by the 5-tuple (A,B,C,D,E)
  is even or divisible by 3.

Does this mean I should treat each word as a binary number? For example:

\$F(0,1,1,0,0) = 1\$ because 01100 is even number.

\$F(0,1,0,0,1)= 1\$  because 01001 is 9 in decimal and 9 is divisible by 3.


texts:
Disclaimer: So this is obviously a silly question and I want to start by saying I don't want to discuss the financial costs of this, as I'm aware CPU cache is expensive. As this hasn't been made obvious enough, this is PURELY ACADEMIC - NOT FOR IMPLEMENTATION. Think "thought experiment"

I've been wondering if it would be possible to precompute all the work an ALU would do and store the results in a lookup table.

For this specific example, I've been looking at a subset of instructions the ALU is responsible for in a MIPS Architecture which is "AND, OR, add, sub, slt, NOR".

In this architecture, these operations would take 4 bits to encode which we'll call the control, as there are only 6 operations. In addition, we'd have to take two 32 bit values as input and return a 32 bit value as output along with 3 1 bit flags. (Details listed here)

At a really high level, we'd use the 4 bit control, along with the two 32 bit inputs to return the 32 bit result and the 3 1 bit flags. So couldn't each control act as an offset to our cache, and use the input values to index into our lookup? We could even squeeze out some more memory for operations that have the commutative property (1+2 = 2+1)

I'm aware this is goofy question but I was curious if anyone had any insight. Perhaps it could be faster? If not, maybe use less electricity or generate less heat? At the very least it's interesting.


texts: I want to use the LAN9500AI controller in an application. This is a USB <-> Ethernet bridge with access to the MII interface. Since I just need the USB and MII interface, the ethernet interface (RXP, RXN, TXP, TXN) will be unconnected. But what's the "default" state of these pins if they are unused? Should I connect pull ups/downs to these pins? (I assume, this is not necessary for TXP, TXN).


texts:
I am building a wind generator with a car alternator without a gearbox.
I know that the alternator is designed to spin at 5-10k RPM and the blades runs at 60-120 RPM so the alternator generates less than 1 volt.
My question is: Can I use a voltage multiplier such as a Cockcroft-Walton generator to get useable voltages at reasonable efficiencies?


texts:
I'm trying to do some basic DC motor (pump) control through an Adafruit Feather Huzzah (ESP8266) and an ULN2803 Darlington transistor array; I've wired it up as follows:

And my code goes a little something like this:

void setup() {
  Serial.begin(9600);
  pinMode(14, OUTPUT);
  analogWrite(14, 0);
}

void loop() {

  if (Serial.available())
  {
    int speed = Serial.parseInt();
    if (speed >= 0 && speed <= 1023)
    {
      analogWrite(14, speed);
      Serial.print("PWM set to ");
      Serial.println(speed);
    }
  }
}

Unfortunately, unless analogWrite() is set to 1023, the motor only humms and does not rotate.

What I've done to troubleshoot:

I've used a (cheap) voltmeter to validate that the voltage going to
the motor is variable as I adjust the analogWrite() value.
Also, I've replaced the motor with a LED strip and it fades properly as I adjust the analogWrite() value.
Finally, I've hooked the motor up to a desktop power supply, and was
able to validate that as I reduce the voltage from 12V to 0V, the
motor slows down.

What am I missing?


texts: first, i started building a simple circuit in the lab just with one Mosfet and now it is working. then i tried to improve it and add another mosfet as cascode topology.as can be seen in the figure. but unfortunately when i am checking  waveforms(ref(sinewave max 1000mv) and current which is passing) i can see a lot of oscillations! i tried to do my best but there is still problem. could you please give me your great suggestions and help me to modify my circuit? what is the problem?


texts: Connecting CDC device to Android over USB-C, with concurrent charging. A cheap option?

texts:
I'm working on a PCB to both charge an Android tablet and also allow Android to connect to the PCB via Serial port (PCB includes an ATMega8u2 configured as a CDC, supplying a Serial port). To enable 500mA charging I have CC1 and CC2 pulled high via a 56k resistor. The CDC device is connected to the D+/D- pins. Here are the problems:

If the D+/D- pins are connected when the Android device is plugged
in, then it will not charge, nor see the CDC device.
If the D+/D- pins are NOT connected when plugged in, then the
Android device will charge. Connecting the D+/D- pins afterwards
(via a MUX chip) does not stop charging, but the Android device
still cannot see the CDC device.
Using an OTG->USB-C cable to the Android device enables it to see
the CDC device, but of course cannot then charge the Android device.
The Android device has no other means of charging.

So my question is, what is the minimum circuit to allow concurrent charging and connection between Android and a CDC peripheral via USB-C? Will I need to use a custom controller chip for this? I am trying to avoid adding a PD controller and circuit if possible, as it will more than double the BOM cost.


texts: Matrix "Multiplexing" with electromagnets, interesting behaviour

texts:
I have an interesting behaviour with my electronics project. I am trying to do something like a LED array but with electromagnets instead. See the schematic below. I built the magnets myself by winding 5 meters of 0.3mm magnet wire around iron nails.
I use relays for the switches. The diodes are rated for high currents.

When I pulse one of the top switches and one of the bottom switches together, I expect only one coil to get powered. BUT the interesting thing is that EVERY magnet pulses a magnetic field, just the one that SHOULD pulse has a more powerful field. I can feel that by holding a permanent magnet next to it.

Please can someone explain this to me, because I dont see how the current can enter the non-connected coils.

simulate this circuit – Schematic created using CircuitLab


texts: How to derive the transfer function of the Inverting Summing Amplifier?

texts:
I know that the transfer function of an inverting summing amplifier gives this, by using the Superposition principle: (for example with 2 input voltages)

\$U_{ out }=-(\frac { R_{ 1 } }{ R_{ f } } U_{ in1 }+\frac { R_{ 2 } }{ R_{ f } } U_{ in2 })\$

However, I don't exactly know how to derive this from the transfer function definition:

\$H = U_{out}/U_{in} = G(U_{+}-U_{-})/U_{in}\$

This is not explained in any book or on the Web. Can anyone explain this?

Thanks a lot!


texts: calculating resistance for LED strips to use as parking lamps and turn signals

texts:
I'm installing LED strips in my car's tail lamps to convert it from conventional bulbs to LEDs. I have a understanding of what I'm doing but not the complete knowledge to make the circuit work correctly without doing some guessing so I figured I would ask here.

This is the product I'm planning on working with and I need a length of 16", 15" and 14" to make then look correct in my housings. When I did the math the 19.7" strips have about 1.5 LEDs per inch and need to be segmented into 3 LED groups so I may have to get creative with the placement.

Ffom what I understand I need 2 diodes and a resistor. One diode on the parking lamp power, and one on the turn signal/brake power and then a resistor on the parking lamp  wire to step down the voltage enough to make them dim enough to use as a parking lamp and distinguish it from the brighter turn/brake lamps.

Does anyone know what size resistor and what size diode to use in this project? The voltage, with the car running, is around 13.8V to the rear lamps. I figure it should be running around 7V to the LEDs to light them as parking lamps.

Also will leaving out a cluster of 3 LEDs change the strips intensity to where I'll need different resistors for each strip?


texts: Weird level shifting issue only when connected to IC chip

texts:
I'm connected to a 5v heat-pump to control it via serial. I'm using a level shifter to shift between the two as the heatpump is 5v and the D1 is 3.3v shown in the scope images below. My issue is I can't read data off the RX line as its voltage is wrong but only when connected to the D1. If I remove the D1 RX pin the voltages are shifted correctly.

Wires coming in from the heat-pump, top, left to right are:  RX, GND, 5V, TX.  5V goes to power the D1 mini which uses a regulator to convert it down to 3.3.

Here is the circuit with the D1 sending data to the HP. Goes out blue at 3.3v and is shifted correctly to 5v. Perfect.

Here is the RX line though coming back into the D1. Yellow is the 5v coming in which is wrong, it doesn't have a low. It's then shifted to an unreadable level for the D1.

The strange part is if I remove the green wire coming from the shifter to the D1 and scope again I get what I would expect. Levels coming in at 5v shifted down to 3.3v.

So the weird voltage issue only happens when it's connected to the D1. I've three different D1 chips (given they all came in the same batch) with the same results. I don't think it's the shifter because of what I see in the last scope. Any idea what's going on here?


texts: BAT54c and TVS SM6T39A application usage?

texts:
I need to design a circuit for my vehicle tracking application and i am using pic micro-controller . I need to capture the iginition status of a vehicle using the micro-controller ,where i have searched the google and  i have designed the voltage divider  circuit.

this circuit is designed for 12v supply . I can understand that by using voltage divider is used in the circuit. i can check the pin as high or low which indicates(on or off).But some trucks have 24v battery in that case when i can change the resistance value. But i don't understand that how both the diodebat54c and   SM6T39A protects the circuit and prevent my micro controller io  pins? I have read the datasheet i dont get any clear idea. please explain me?


texts: Multimeter across Power Line voltage varies wildly

texts:
I'm building a single switched AC/DC Forward Converter and have reached to the point where I have steady o/p voltages and currents.

However, I am not able to remove noise that goes back into the AC i/p line. A multi-meter(DMM) placed across the Line and Neutral at the power line input jumps around wildly once the current starts flowing in the MOSFET. The o/p voltages and currents remain steady, however.

I tried reading the AC with an analog meter, but not much difference. As long as the load current is small, it shows correct AC voltage. But as the load current increases, the meter starts showing much higher voltage (roughly 400VAC)across the input.

I have tried various Y capacitors between i/p phase to Earth, Neutral to Earth, from the MOSFET source to Earth, but to no avail.

I have tried one commercial EMI filter also, but nope.
I have tried with a common mode filter that I rigged up, but either my design is wrong, or I haven't got the concept right, because it did not make any difference.
Some pointers/URLs for a design procedure to correctly design EMI/RFI filters will be appreciated.

My configuration is a single switch Forward converter with 230VAC Power Line Input, a reset winding (Treset=Tprimary), and a P6KE350 diode as protection from Drain to +ve bus after rectifier and capacitor. The controller is a Micro. Switching frequency is 50KHz. The MOSFET is a 6NB80, 5N90 or IRFBE30, depending on availability.

The output voltage and currents readings are very stable, but not the i/p readings.

Your suggestions,recommendations and advice sought.
Thanks in advance
Edit: Added Schematic. My Measurement equipment are small DMMs, an old 25MHz analog scope, and not much else. I also have a Rigol-1052 50MHz DSO, but not used that for this project yet.

2nd Edit: The Micro is also being supplied from AC, with a smaller 1N4007 rectifer, and a TNY278 circuit on the same PCB. I had thought the combination of the TNY278 ckt and the Fwd converter running together could be the cause of this noise(beat frequency?) so I disconnected the track supplying the ac to the 278 part of the ckt, and supplied the micro from a 12v7AH  battery, just to eliminate this as a possible cause.
Again, no difference.


texts: How to wire AC power to an integrated DPST switch?

texts:
I have an IEC C14 power connector (like those on PC power supplies).  The connector has an integrated DPST switch, however the power pins are not connected directly to the switch-- I have to do that myself.

My first question is: Why have a DPST switch?  Why not just a single pole that I wire to the line voltage?

The second question is: Which side to I wire the hot wire to?  One set of the pins on the switch are divided by a small plastic divider.

Here is a picture:
IEC C14 connector


texts: Input Bias Compensation for a Comparator

texts:
I've been working on designing a discrete dual-slope ADC for school, and I've run into a problem. The schematic below shows my proposed input stage, an ideal integrator connected to a comparator. I've learned that you can reduce the input bias current by adding a compensating resistor to the non-inverting terminal of an op-amp.

simulate this circuit – Schematic created using CircuitLab

Since the capacitor behaves like an open circuit at DC, RC1 would presumably be the same value as R2, but I'm not sure how to compensate for the input bias current of the comparator. Here is what I've come up with so far:

Since the goal of a compensation resistor is to match the resistance seen by the two input terminals, I would expect RC2 to be the parallel combination of the output resistance of the op-amp and the input resistance of the comparator. In other words: \$R_{C2} = R_o \parallel R_{i+}\$. My problem is that both of those resistances are difficult to predict.

Questions:

Is there some other way to compensate for the input bias current for the comparator? Is it necessary?
Will the input offset voltage and input bias current of the comparator have a significant effect on the op-amp integrator?
What other ways can I compensate?

I intend to use a precision op-amp and comparator.


texts:
this time I'd like to ask a few questions about capacitors, all noob questions again;

What's a better idea, having one capacitor at 5x farads or five capacitors at x farads each? I want to get a certain amount of voltage and want to discharge the direct current as fast as possible.
I'm trying to build an amateur railgun, and intend to shoot projectiles that weigh about 10 grams. Using the formula that someone helped me with in my other question, in order to give that a speed of 100m/s at a total of 20.000 uF assuming 2% efficiency I'd need a little less than 112V's. The question is, is this amount of voltage I need my capacitor or series of capacitors to provide for the duration of the shooting?
What determines how much voltage a capacitor can hold? This may come off stupid as I am aware that there is a voltage rating when you buy them, but better safe than sorry.
I was only assuming 2% efficiency, and depending on my rail length it could be higher. The question is, what determines how fast the capacitor will discharge and how it can be prevented from going above the rated voltage?


texts: Can anyone tell me what other computers used this floating-point format?

texts:
I have discovered that the DEC PDP-10 used a floating-point format that differed from IEEE-754 in an interesting way.

IEEE-754 is like sign-magnitude representation.  The only difference between a positive value and its negative is the value of the MSB of the word.  Assuming no NaNs, if you use an integer subtractor to compare two IEEE floats, the compare operation yields the correct result in 3 out of 4 cases.  The case where the integer compare result is wrong is when both values are negative.

The DEC PDP-10 had the same mantissa with "hidden 1 bit", offset binary exponent to the left of the mantissa, but when the numbers were negative, the PDP-10 represented that value as the 2's complement of the positive value.  So there was no "-0" representation (just one 0) and the integer compare operation worked in any case.

This is clever.  I wonder what other early computers may have used this and why didn't this catch on with IEEE?

If you combine this clever formatting with floats with denormals, you can have a floating-point representation that is monotonic mapping that is a piecewise-linear approximation to the arcsinh() function when mapping the floating-point value to an integer having the same bit pattern in the word.  Seems like a clever idea missed by whatever IEEE committee that first came up with 754.

I suppose they wanted "-0" so that if an operation like 1/x was done, they would know whether to use +INF or -INF, but if you leave that "feature" out and leave out NaNs, this format can assign every bit pattern to a numerical value that is a strictly-increasing mapping and that seems like a valuable feature.  Every bit pattern is a number and a unique number.  No NaNs or INFs or other goofy bit patterns to cause an exception.


texts: Why is the output volume lower on a 1 transistor preamp

texts: I built the simple common emitter 1 transistor preamp with a 2n3904 from hackaweek (http://hackaweek.com/hacks/?p=327) and hooked it up to my iPod as a test. When I had the small earbuds on my iPods output, the volume was louder than the preamps output. Why is this and why is it called an amp if it attenuates?


texts: Schematic representation for net connected to specific component

texts:
I have a board with a +5V trace from a current sense resistor across a noisy +5V plane to an OpAmp, so I thought I'd shave that particular yak soon and create a few symbols for KiCad that actually behave as expected.

How would I express in a schematic the constraint to connect this trace only to a specific pad on a specific component, even if the same net is available nearer?

I'm interested mainly in the graphical representation, because from a program logic POV it is easy to implement (separate net from ratsnest POV, same net from DRC POV), but I'd like to have a readable schematic as well.

Similarly, is there a standard for denoting decoupling capacitors and their mapping to IC pins (same problem class, basically)?

Obviously, if there are multiple standards (US, Europe, Russia) I'd like to know about that as well.


texts:
On the Internet I found FSK generator connection diagram. And I'm trying to connect up it in Qucs.
I' sure, 555 timer is working properly. But at the output of the whole schema I get unclear result.

P.S. Output.Vt does not depend on the input bit stream.

Look, please, what could be wrong?


texts:
Please give me some help or tip about this question, I need to make a simulation of this on proteus:

" Using full adder(FA) design a adder for numbers in base 8(octal)

6(8) + 4(8) = 12(8)   "

As you can see I transfer this two numbers to binary, and then i get: 110+100=1010
Then, I resolve the table and get the simplify function like this:

Look that I get two function ( the adder and the carry out). So whats wrong with my posible solution?

P.D: Sorry for my bad vocabulary and orthography, this is cause the english is not my native language

Thanks.


texts: How to seamlessly switch between dc lipo power sources

texts:
I have a question which has been asked a few times on here with some very detailed replies ...which would be great, if I had any idea what they meant! I've been building my own RC FPV setup and groundstation and so far been ok but now stuck.

I want to switch between 2x 4000 mah Lipo 3 cell batteries with a SPDT On-On toggle switch. I am not sure what devices I will need to do this somewhat properly. I'm pretty sure I shouldn't be simply connecting both lipo's to either throw and the output into my ground station so I can toggle without dropping the flow.

I was hoping someone might be able to link me to the devices I should be connecting together so I can "seamlessly" switch between power sources. I can't read circuit diagrams too well and electrical jargon (still learning) ...so hoping for a more straightforward approach.

Thanks for any help.

Cheers


texts: Is solder mask a valid electrical insulator?

texts:
I had some PCBs manufactured prior to ordering all of my components :-(
It turns out that the surface mounted 1W LEDs I'm going to use have the heat slug connected internally to the LED's +ve terminal. Unfortunately I have a copper pour over the entire top of my boards, and it's part of the GND net.
Can I rely on the solder mask to insulate the +ve voltage (~3V ish) from GND? Long term?
Edit following comment:-

Simple home project to run in my man cave.
Once built, will not really be moved.
The led will only run @ 100 mA. I just like their size and spread.
If insulation fails, it will be a direct short across a modern 5.1V/2.5A wall brick switcher. Not really a biggie as there's a dropper resistor.

I'm just curious for the future...


texts: How to determine I2C Master timing parameters

texts:
I am relatively new to I2C, but I have done much reading on the topic and I am confused as to the timing parameters necessary when designing an I2C Master.

I know of this chart from the manual on page 48.

However it gives a large range of possible values.

For example, I need to set the following parameters for my I2C Master (using a National Instruments program) in Standard-Mode:

tSU;STA - MIN = 4700 ns
tHD;STA - MIN = 4000 ns
tSU;DAT - MIN = 250 ns
tHD;DAT - MIN = 0 ns
tSU;STO - MIN = 4000 ns
tBUF - MIN = 4700 ns
tHIGH - MIN = 4000 ns
fSCL - MIN = 0 - MAX = 100 kHz

How can I calculate the appropriate values for my I2C bus for all of the above?

Do you always use the minimum, does it matter how many slave devices there are, etc?


texts: Switched reluctance motor with rotating windings?

texts: In a normal switched reluctance motor the electromagnets are on the stator and the iron is on the rotor. I'm wondering would a switched reluctance motor work with spinning windings and stationary iron (assuming you could get electricity to the spinning windings)?


texts: Peak-to-Average Power Ratio in OFDMA Communication

texts:
I am looking for a formula to calculate the Average Power of a square wave used in APSK Modulation.

In my textbook, the example above is given with no formula so I am a loss how the value for average power (4.5) is calculated in the bottom example.

I assumed from the top example that it was simply the square of the amplitude divided by the ON Time Period, but applying that logic to the bottom example gives a value no where near so I have a feeling some integration may be involved.

Any suggestions would be greatly appreciated.


texts:
I have a AM/FM radio board I found and am trying get playing through a small speaker.  The other components were missing so I don't know how this connects to the rest of the system which had a CD player, tape deck and the like.

The board has a single set of input wires pictured below.

The on board chip is a Toshiba TA8167N which I have found runs on 3 volts and have managed to power.  Now I am trying to figure out what is required to connect to the speaker.

As there is only a single out for L and R which connect to the 'R-Out' and 'L-Out' pins on the chip I'm not sure how to complete the circuit.  From reading around it looks like I need an 'R-Ret' and 'L-Ret' respectively to complete it but there is no wiring for this available.

I think SL connects to the Stereo LED but I can't follow the MO or MU to the chip as the connections sit under the tuning wheel.

EDIT:

PCB picture added.


texts: Using a triac plus an H-bridge to switch DC or AC

texts:
I've been working on a controller for inductive loads, and I want the system to be compatible with either DC or AC loads. I've got a 24V to 34V DC boost regulator powering an H-bridge, which is creating a sine wave OR just sending out straight DC. Now I want to multiplex this output to eight separate channels using a triac or similar device. I've already looked into using more half bridges or using SSRs. Both are too expensive for my application.

My question is, can I use triacs in this application to switch either the DC or the AC output from the two half bridges? I understand that triacs can only be turned "on" in DC, but if I can control the H-bridge, could I disable the output to turn the triac off?


texts:
I have been working on a project that requires me to boost 1V to 5V. I have found a ready-to-use boost regulator that gets the job done. The problem is that I need to get the circuit simulated on OrCad Pspice but the CE8301 CMOS PFM-control
step-up switching DC/DC converter is not included in the library.

I have the block diagram of CE8301. Is there a way to add this component by hand to PSspice library so that I can simulate the circuit below.

Also, block diagram is included in the attachments.


texts: Trouble finding Thévenin equivalent for this circuit

texts:
I'm having trouble finding the thevenin equivalent for this circuit

To solve this problem, I changed the voltages from 20V and 5V to 25V and 0V as shown below

My resulting output voltage is 10V and the Thévenin resistance is 6K ohms. Now the answers says that the output voltage is 5V and 6K ohms.

Confused, I tried a different method, superposition

and I still got the same output voltage of 10V!

Have I done my circuit analysis correctly, or am I missing a crucial step???


texts: Why is my I2C device (VCNL4200) sending all zeros when I read from it, regardless of register?

texts:
Whenever I read from my VCNL4200 over I2C, the 16bit word I get back is always 0x0000. This is completely independent of the register I'm reading, and still happens when reading the device ID register which has a fixed non-zero value. This has happened on both sensor chips I've tried.

As best I can tell the device reads I2C commands correctly, as I've probed it and verified that the device is doing what my setup function tells it to do. It's also behaving correctly with ACK/NACK bits (pulling low for ACK during write, letting SDA float for the micro to ACK during read).

The scope traces for SDA and SCL when I try to read the device ID register are below.

Code I use to read/setup the sensor:

//count is number of bits, stop is whether or not there is a stop condition at the end
int i2cWrite(int8 address, int8 *data, int8 count, int1 stop);
int i2cRead(int8 address, int8 *data, int8 count);

int16 VCNL4200_Read(void) {
    int8 data[2] = {0};
    int8 psDataRegister[1] = {0x0E}; //0x08 is the address of the data, 0x0E for device ID
    i2cWrite(VCNL4200_I2C_ADDRESS, psDataRegister, 1, 1);
    i2cRead(VCNL4200_I2C_ADDRESS, data, 2);
    return make16(data[1], data[0]);
}

void VCNL4200_Setup(void) {
    int8 configWords[5][2]  = {
        {0xF0, 0x00},   //PS_CONF1 , PS_CONF2
        {0x00, 0x20},   //PS_CONF3 , PS_MS
        {0x00, 0x00},   //PS_CANC_L, PS_CANC_H
        {0x00, 0x00},   //PS_THDL_L, PS_THDL_H
        {0x01, 0x00}    //PS_THDH_L, PS_THDH_H
    };
    int8 configWordCurrent[3];

    for(int8 i = 0; i < 5; i++){
        configWordCurrent[0] = i+3;                             //1st byte, register address. Sequential from 0x03 to 0x07
        configWordCurrent[1] = configWords[i][0];               //2nd byte, lower byte of config word
        configWordCurrent[2] = configWords[i][1];               //3rd byte, upper byte of config word
        i2cWrite(VCNL4200_I2C_ADDRESS, configWordCurrent, 3, 1);//Send over I2C
    }
}

The i2cWrite and i2cRead functions have been verified as working on other devices.
I'm using a PIC16F1776 with CCS C compiler.


texts: What PolyFuse should I have to protect 150 Ohms 0.5W resistor?

texts:
I need help selecting a polyfuse for protecting a 150 Ohms 0.5W resistor.
My goals are:

To make sure that the resistor won't take any damage when I apply voltage over 3V onto the 150 Ohm resistor
I must be possible apply 3V or below onto the 150 Ohm resistor, without the PolyFuse should "wake up" and turn down the current by increasing the resistanse.

What do you think I should select? A or B?
I want to select A but the problem is that if I apply 20mA, it will take 100 seconds for the polyfuse to "wake up" and break down the current. 20mA over 150 Ohm resistor is 3V. So I don't know what to select. Do you have any suggestions?

http://www.farnell.com/datasheets/2830168.pdf?_ga=2.213747988.1004593585.1603574478-32033874.1602687410


texts: Why did my soldering iron tip turn blue?

texts:
I tinned the iron and removed the solder after it but as I removed it suddenly turned strangely blue. It is a brand new soldering iron tip rated perfectly for 60 watts.  While tinning I noticed some flux boiling in one corner developing black layer beneath it.
But the tips functions and heat normally


texts: Hello all I have seen some smps use output secondary for feedback using via opto coupler. And in other smpa i have seen they use primary aux winding feedback only. Which one is good to use and easly troubleshoot.


texts: Altium Design Rule - Selecting Pads Whose Parent Component is not type "No BOM"

texts: I can create a query to select only pads and a query to select only components who are not type "No BOM", but I can't seem to find a way to put these together to create a design rule that only selects pads from components that are not type "No BOM".  Any ideas?


texts: How to determine the units when reading a multimeter?

texts:
Say for instance I am trying to measure the current. The units around the edge of the multimeter is 2000u, 200m, 20m, 10A, etc.

Does this mean that the reading displayed on the multimeter is in that particular unit? For example, if I set it to 20m and the reading stated "0.5", does this mean it is 0.5 * 20mA = 10mA = 0.01A?


texts: How can I connect polygons 1 and 2 together? It tried to make a trace + vias between them, but Eagle won't let me create a trace on a polygon.


texts: How should I select the resistors for this constant-current application for a 317?

texts:
Over at OnSemi, they have a little doc about using a 317 voltage-reg as a current source:
http://www.onsemi.com/pub_link/Collateral/AND8109-D.PDF

Their final example, providing constant current to an indeterminate number of strings of LED's is exactly what I'm looking for. I, somewhat, grasp how to choose the value of the "sense" resistor for each string, but they don't explain how to choose the resistor on the base of the transistor... and it's not completely clear to me what will happen if I choose a value which is too low, too high, and how to choose the optimum value.


texts: How to interface a SPST switch with minimal current (1µA)?

texts:
The usual way to wire up a SPST switch to a MCU is by means of a pull-up resistor. However, this wastes current when the switch is closed. If this switch is used to wake up the MCU from sleep, then this current (100-500 µA) is significant compared to the sleep current (< 0.1 µA). I imagine increasing the resistor value up to megaohms wouldn't be practical for a number of reasons. So is there a better way to interface a SPST in general? I have a couple of pins on the MCU to spare (but keep in mind the MCU has to be put in sleep most of the time - it should wake up and do its stuff only when the switch state changes).

The only solution that comes to my mind is to basically use the pull-up scheme, but buffer it through a P-MOSFET/N-MOSFET pair for increased input impedance.

And yes, I realize the solution is trivial if we were dealing with a SPDT or a push-button.


texts: Connect Thick thermocouple wire to Type K Connector

texts: I have purchased a high-temperature K type thermocouple that has two 14 gauge solid leads. I wanted to know what the best way to go about connecting these leads to a type K connector would be.


texts: PCB with KiCAD: Possible error in routing decoupling capacitors

texts:
I was inspecting my work with my first PCB in KiCAD.
I was looking at the 3d model, and I was checking out the three decoupling capacitors I have placed.
I noticed that they do not actually connect with an IC (no trace.)

Of course, I made sure I routed all the ratsnest properly - and there are zero unrouted.
These capacitors, like I said are decoupling capacitors.
This means one pin is connected to Vdd and one to GND of the IC.
The Vdd of all the ICs is the front copper plane (5V) and the GND of all the ICs is the back copper plane.
My capacitors connect to the front copper plane and the back copper plane and that's it. No connection to ICs.
But, since the ICs connect to these planes, in order to get their power and GND connections, the ratsnest check is satisfied, and that ratsnest is cleared.
But I see no actual connection of an IC to one particular decoupling capacitor!
Isn't this like now there are three 100nF capacitors in parallel between the Vdd and GND?
So isn't it like one 300nF capacitor that between the two planes, that all the three ICs share?
Have I done something wrong?
I also post picturess of the schematic as an example and the actual PCB.


texts:
I have this problem that I need a 120hz power supply whit 220 Volts for my project.
Does any one have any suggestion about haw to doing it or help me whit some schematics like a converter that I can use?!! My main Voltage source is 220v in 60hz.


texts:
I have an in-car charger left after I sold the GPS localizer. According to Wikipedia, it uses "UC-E6 proprietary (non-USB) plug" (second to the left on this photo).

Does anyone know any device, that uses the same plug. Or is there a DIY kit for assembling such a device? Or maybe someone heard about any adapter, that could be used with this charger and any standard microUSB device?

I'm trying to determine, if I can find any usage for this charger or if I should throw it away, since I got rid of the original device (GPS localizer),that used it.


texts:
I tried to detect 220V AC in my microcontroller using SFH620A-3 with series resistance of 440K (2 x 220K, 1/4 watts SMD type), a 1uF at the output to smoothen the pulse and every works as expected. However the resistors produces good amount of heat specifically when placed in a closed enclosure. The heat is not high to start a fire (I can still touch), however the heat slowly propagates across the PCB and other components too get hot. I did the power calculations and the voltage across the opto is less that 1mA and the power dissipation is 130mW on each resistor. I may have multiple AC detection circuit on a single board and hence the heat would multiply.

Is it a good practice to increase the resistance further? I tried some 800K and the output wasn't reliable.
Are there other ways to reduce the heat ?
Should I try another AC optocouplers ? If yes, can someone suggest some AC optocouplers (DIP-4 casing).

Schematics

simulate this circuit – Schematic created using CircuitLab

Note : Transformers wont be feasible due to the size.

Update

I tried increasing the resistance by 100K, 50K etc and found that the opto fails to work at around 900K. The output seems to be stable at 770K, hence can I safely use 660K for my project (i.e 330K x 2) ?